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alloc.c

/* -*- mode: c; c-basic-offset: 8; -*-
 * vim: noexpandtab sw=8 ts=8 sts=0:
 *
 * alloc.c
 *
 * Extent allocs and frees
 *
 * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#include <linux/fs.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/highmem.h>
#include <linux/swap.h>
#include <linux/quotaops.h>

#define MLOG_MASK_PREFIX ML_DISK_ALLOC
#include <cluster/masklog.h>

#include "ocfs2.h"

#include "alloc.h"
#include "aops.h"
#include "blockcheck.h"
#include "dlmglue.h"
#include "extent_map.h"
#include "inode.h"
#include "journal.h"
#include "localalloc.h"
#include "suballoc.h"
#include "sysfile.h"
#include "file.h"
#include "super.h"
#include "uptodate.h"
#include "xattr.h"

#include "buffer_head_io.h"


/*
 * Operations for a specific extent tree type.
 *
 * To implement an on-disk btree (extent tree) type in ocfs2, add
 * an ocfs2_extent_tree_operations structure and the matching
 * ocfs2_init_<thingy>_extent_tree() function.  That's pretty much it
 * for the allocation portion of the extent tree.
 */
00064 struct ocfs2_extent_tree_operations {
      /*
       * last_eb_blk is the block number of the right most leaf extent
       * block.  Most on-disk structures containing an extent tree store
       * this value for fast access.  The ->eo_set_last_eb_blk() and
       * ->eo_get_last_eb_blk() operations access this value.  They are
       *  both required.
       */
      void (*eo_set_last_eb_blk)(struct ocfs2_extent_tree *et,
                           u64 blkno);
      u64 (*eo_get_last_eb_blk)(struct ocfs2_extent_tree *et);

      /*
       * The on-disk structure usually keeps track of how many total
       * clusters are stored in this extent tree.  This function updates
       * that value.  new_clusters is the delta, and must be
       * added to the total.  Required.
       */
      void (*eo_update_clusters)(struct inode *inode,
                           struct ocfs2_extent_tree *et,
                           u32 new_clusters);

      /*
       * If ->eo_insert_check() exists, it is called before rec is
       * inserted into the extent tree.  It is optional.
       */
      int (*eo_insert_check)(struct inode *inode,
                         struct ocfs2_extent_tree *et,
                         struct ocfs2_extent_rec *rec);
      int (*eo_sanity_check)(struct inode *inode, struct ocfs2_extent_tree *et);

      /*
       * --------------------------------------------------------------
       * The remaining are internal to ocfs2_extent_tree and don't have
       * accessor functions
       */

      /*
       * ->eo_fill_root_el() takes et->et_object and sets et->et_root_el.
       * It is required.
       */
      void (*eo_fill_root_el)(struct ocfs2_extent_tree *et);

      /*
       * ->eo_fill_max_leaf_clusters sets et->et_max_leaf_clusters if
       * it exists.  If it does not, et->et_max_leaf_clusters is set
       * to 0 (unlimited).  Optional.
       */
      void (*eo_fill_max_leaf_clusters)(struct inode *inode,
                                struct ocfs2_extent_tree *et);
};


/*
 * Pre-declare ocfs2_dinode_et_ops so we can use it as a sanity check
 * in the methods.
 */
static u64 ocfs2_dinode_get_last_eb_blk(struct ocfs2_extent_tree *et);
static void ocfs2_dinode_set_last_eb_blk(struct ocfs2_extent_tree *et,
                               u64 blkno);
static void ocfs2_dinode_update_clusters(struct inode *inode,
                               struct ocfs2_extent_tree *et,
                               u32 clusters);
static int ocfs2_dinode_insert_check(struct inode *inode,
                             struct ocfs2_extent_tree *et,
                             struct ocfs2_extent_rec *rec);
static int ocfs2_dinode_sanity_check(struct inode *inode,
                             struct ocfs2_extent_tree *et);
static void ocfs2_dinode_fill_root_el(struct ocfs2_extent_tree *et);
static struct ocfs2_extent_tree_operations ocfs2_dinode_et_ops = {
      .eo_set_last_eb_blk     = ocfs2_dinode_set_last_eb_blk,
      .eo_get_last_eb_blk     = ocfs2_dinode_get_last_eb_blk,
      .eo_update_clusters     = ocfs2_dinode_update_clusters,
      .eo_insert_check  = ocfs2_dinode_insert_check,
      .eo_sanity_check  = ocfs2_dinode_sanity_check,
      .eo_fill_root_el  = ocfs2_dinode_fill_root_el,
};

static void ocfs2_dinode_set_last_eb_blk(struct ocfs2_extent_tree *et,
                               u64 blkno)
{
      struct ocfs2_dinode *di = et->et_object;

      BUG_ON(et->et_ops != &ocfs2_dinode_et_ops);
      di->i_last_eb_blk = cpu_to_le64(blkno);
}

static u64 ocfs2_dinode_get_last_eb_blk(struct ocfs2_extent_tree *et)
{
      struct ocfs2_dinode *di = et->et_object;

      BUG_ON(et->et_ops != &ocfs2_dinode_et_ops);
      return le64_to_cpu(di->i_last_eb_blk);
}

static void ocfs2_dinode_update_clusters(struct inode *inode,
                               struct ocfs2_extent_tree *et,
                               u32 clusters)
{
      struct ocfs2_dinode *di = et->et_object;

      le32_add_cpu(&di->i_clusters, clusters);
      spin_lock(&OCFS2_I(inode)->ip_lock);
      OCFS2_I(inode)->ip_clusters = le32_to_cpu(di->i_clusters);
      spin_unlock(&OCFS2_I(inode)->ip_lock);
}

static int ocfs2_dinode_insert_check(struct inode *inode,
                             struct ocfs2_extent_tree *et,
                             struct ocfs2_extent_rec *rec)
{
      struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);

      BUG_ON(OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL);
      mlog_bug_on_msg(!ocfs2_sparse_alloc(osb) &&
                  (OCFS2_I(inode)->ip_clusters !=
                   le32_to_cpu(rec->e_cpos)),
                  "Device %s, asking for sparse allocation: inode %llu, "
                  "cpos %u, clusters %u\n",
                  osb->dev_str,
                  (unsigned long long)OCFS2_I(inode)->ip_blkno,
                  rec->e_cpos,
                  OCFS2_I(inode)->ip_clusters);

      return 0;
}

static int ocfs2_dinode_sanity_check(struct inode *inode,
                             struct ocfs2_extent_tree *et)
{
      struct ocfs2_dinode *di = et->et_object;

      BUG_ON(et->et_ops != &ocfs2_dinode_et_ops);
      BUG_ON(!OCFS2_IS_VALID_DINODE(di));

      return 0;
}

static void ocfs2_dinode_fill_root_el(struct ocfs2_extent_tree *et)
{
      struct ocfs2_dinode *di = et->et_object;

      et->et_root_el = &di->id2.i_list;
}


static void ocfs2_xattr_value_fill_root_el(struct ocfs2_extent_tree *et)
{
      struct ocfs2_xattr_value_buf *vb = et->et_object;

      et->et_root_el = &vb->vb_xv->xr_list;
}

static void ocfs2_xattr_value_set_last_eb_blk(struct ocfs2_extent_tree *et,
                                    u64 blkno)
{
      struct ocfs2_xattr_value_buf *vb = et->et_object;

      vb->vb_xv->xr_last_eb_blk = cpu_to_le64(blkno);
}

static u64 ocfs2_xattr_value_get_last_eb_blk(struct ocfs2_extent_tree *et)
{
      struct ocfs2_xattr_value_buf *vb = et->et_object;

      return le64_to_cpu(vb->vb_xv->xr_last_eb_blk);
}

static void ocfs2_xattr_value_update_clusters(struct inode *inode,
                                    struct ocfs2_extent_tree *et,
                                    u32 clusters)
{
      struct ocfs2_xattr_value_buf *vb = et->et_object;

      le32_add_cpu(&vb->vb_xv->xr_clusters, clusters);
}

static struct ocfs2_extent_tree_operations ocfs2_xattr_value_et_ops = {
      .eo_set_last_eb_blk     = ocfs2_xattr_value_set_last_eb_blk,
      .eo_get_last_eb_blk     = ocfs2_xattr_value_get_last_eb_blk,
      .eo_update_clusters     = ocfs2_xattr_value_update_clusters,
      .eo_fill_root_el  = ocfs2_xattr_value_fill_root_el,
};

static void ocfs2_xattr_tree_fill_root_el(struct ocfs2_extent_tree *et)
{
      struct ocfs2_xattr_block *xb = et->et_object;

      et->et_root_el = &xb->xb_attrs.xb_root.xt_list;
}

static void ocfs2_xattr_tree_fill_max_leaf_clusters(struct inode *inode,
                                        struct ocfs2_extent_tree *et)
{
      et->et_max_leaf_clusters =
            ocfs2_clusters_for_bytes(inode->i_sb,
                               OCFS2_MAX_XATTR_TREE_LEAF_SIZE);
}

static void ocfs2_xattr_tree_set_last_eb_blk(struct ocfs2_extent_tree *et,
                                   u64 blkno)
{
      struct ocfs2_xattr_block *xb = et->et_object;
      struct ocfs2_xattr_tree_root *xt = &xb->xb_attrs.xb_root;

      xt->xt_last_eb_blk = cpu_to_le64(blkno);
}

static u64 ocfs2_xattr_tree_get_last_eb_blk(struct ocfs2_extent_tree *et)
{
      struct ocfs2_xattr_block *xb = et->et_object;
      struct ocfs2_xattr_tree_root *xt = &xb->xb_attrs.xb_root;

      return le64_to_cpu(xt->xt_last_eb_blk);
}

static void ocfs2_xattr_tree_update_clusters(struct inode *inode,
                                   struct ocfs2_extent_tree *et,
                                   u32 clusters)
{
      struct ocfs2_xattr_block *xb = et->et_object;

      le32_add_cpu(&xb->xb_attrs.xb_root.xt_clusters, clusters);
}

static struct ocfs2_extent_tree_operations ocfs2_xattr_tree_et_ops = {
      .eo_set_last_eb_blk     = ocfs2_xattr_tree_set_last_eb_blk,
      .eo_get_last_eb_blk     = ocfs2_xattr_tree_get_last_eb_blk,
      .eo_update_clusters     = ocfs2_xattr_tree_update_clusters,
      .eo_fill_root_el  = ocfs2_xattr_tree_fill_root_el,
      .eo_fill_max_leaf_clusters = ocfs2_xattr_tree_fill_max_leaf_clusters,
};

static void ocfs2_dx_root_set_last_eb_blk(struct ocfs2_extent_tree *et,
                                u64 blkno)
{
      struct ocfs2_dx_root_block *dx_root = et->et_object;

      dx_root->dr_last_eb_blk = cpu_to_le64(blkno);
}

static u64 ocfs2_dx_root_get_last_eb_blk(struct ocfs2_extent_tree *et)
{
      struct ocfs2_dx_root_block *dx_root = et->et_object;

      return le64_to_cpu(dx_root->dr_last_eb_blk);
}

static void ocfs2_dx_root_update_clusters(struct inode *inode,
                                struct ocfs2_extent_tree *et,
                                u32 clusters)
{
      struct ocfs2_dx_root_block *dx_root = et->et_object;

      le32_add_cpu(&dx_root->dr_clusters, clusters);
}

static int ocfs2_dx_root_sanity_check(struct inode *inode,
                              struct ocfs2_extent_tree *et)
{
      struct ocfs2_dx_root_block *dx_root = et->et_object;

      BUG_ON(!OCFS2_IS_VALID_DX_ROOT(dx_root));

      return 0;
}

static void ocfs2_dx_root_fill_root_el(struct ocfs2_extent_tree *et)
{
      struct ocfs2_dx_root_block *dx_root = et->et_object;

      et->et_root_el = &dx_root->dr_list;
}

static struct ocfs2_extent_tree_operations ocfs2_dx_root_et_ops = {
      .eo_set_last_eb_blk     = ocfs2_dx_root_set_last_eb_blk,
      .eo_get_last_eb_blk     = ocfs2_dx_root_get_last_eb_blk,
      .eo_update_clusters     = ocfs2_dx_root_update_clusters,
      .eo_sanity_check  = ocfs2_dx_root_sanity_check,
      .eo_fill_root_el  = ocfs2_dx_root_fill_root_el,
};

static void __ocfs2_init_extent_tree(struct ocfs2_extent_tree *et,
                             struct inode *inode,
                             struct buffer_head *bh,
                             ocfs2_journal_access_func access,
                             void *obj,
                             struct ocfs2_extent_tree_operations *ops)
{
      et->et_ops = ops;
      et->et_root_bh = bh;
      et->et_root_journal_access = access;
      if (!obj)
            obj = (void *)bh->b_data;
      et->et_object = obj;

      et->et_ops->eo_fill_root_el(et);
      if (!et->et_ops->eo_fill_max_leaf_clusters)
            et->et_max_leaf_clusters = 0;
      else
            et->et_ops->eo_fill_max_leaf_clusters(inode, et);
}

void ocfs2_init_dinode_extent_tree(struct ocfs2_extent_tree *et,
                           struct inode *inode,
                           struct buffer_head *bh)
{
      __ocfs2_init_extent_tree(et, inode, bh, ocfs2_journal_access_di,
                         NULL, &ocfs2_dinode_et_ops);
}

void ocfs2_init_xattr_tree_extent_tree(struct ocfs2_extent_tree *et,
                               struct inode *inode,
                               struct buffer_head *bh)
{
      __ocfs2_init_extent_tree(et, inode, bh, ocfs2_journal_access_xb,
                         NULL, &ocfs2_xattr_tree_et_ops);
}

void ocfs2_init_xattr_value_extent_tree(struct ocfs2_extent_tree *et,
                              struct inode *inode,
                              struct ocfs2_xattr_value_buf *vb)
{
      __ocfs2_init_extent_tree(et, inode, vb->vb_bh, vb->vb_access, vb,
                         &ocfs2_xattr_value_et_ops);
}

void ocfs2_init_dx_root_extent_tree(struct ocfs2_extent_tree *et,
                            struct inode *inode,
                            struct buffer_head *bh)
{
      __ocfs2_init_extent_tree(et, inode, bh, ocfs2_journal_access_dr,
                         NULL, &ocfs2_dx_root_et_ops);
}

static inline void ocfs2_et_set_last_eb_blk(struct ocfs2_extent_tree *et,
                                  u64 new_last_eb_blk)
{
      et->et_ops->eo_set_last_eb_blk(et, new_last_eb_blk);
}

static inline u64 ocfs2_et_get_last_eb_blk(struct ocfs2_extent_tree *et)
{
      return et->et_ops->eo_get_last_eb_blk(et);
}

static inline void ocfs2_et_update_clusters(struct inode *inode,
                                  struct ocfs2_extent_tree *et,
                                  u32 clusters)
{
      et->et_ops->eo_update_clusters(inode, et, clusters);
}

static inline int ocfs2_et_root_journal_access(handle_t *handle,
                                     struct inode *inode,
                                     struct ocfs2_extent_tree *et,
                                     int type)
{
      return et->et_root_journal_access(handle, inode, et->et_root_bh,
                                type);
}

static inline int ocfs2_et_insert_check(struct inode *inode,
                              struct ocfs2_extent_tree *et,
                              struct ocfs2_extent_rec *rec)
{
      int ret = 0;

      if (et->et_ops->eo_insert_check)
            ret = et->et_ops->eo_insert_check(inode, et, rec);
      return ret;
}

static inline int ocfs2_et_sanity_check(struct inode *inode,
                              struct ocfs2_extent_tree *et)
{
      int ret = 0;

      if (et->et_ops->eo_sanity_check)
            ret = et->et_ops->eo_sanity_check(inode, et);
      return ret;
}

static void ocfs2_free_truncate_context(struct ocfs2_truncate_context *tc);
static int ocfs2_cache_extent_block_free(struct ocfs2_cached_dealloc_ctxt *ctxt,
                               struct ocfs2_extent_block *eb);

/*
 * Structures which describe a path through a btree, and functions to
 * manipulate them.
 *
 * The idea here is to be as generic as possible with the tree
 * manipulation code.
 */
00458 struct ocfs2_path_item {
      struct buffer_head            *bh;
      struct ocfs2_extent_list      *el;
};

#define OCFS2_MAX_PATH_DEPTH  5

00465 struct ocfs2_path {
      int                     p_tree_depth;
      ocfs2_journal_access_func     p_root_access;
      struct ocfs2_path_item        p_node[OCFS2_MAX_PATH_DEPTH];
};

#define path_root_bh(_path) ((_path)->p_node[0].bh)
#define path_root_el(_path) ((_path)->p_node[0].el)
#define path_root_access(_path)((_path)->p_root_access)
#define path_leaf_bh(_path) ((_path)->p_node[(_path)->p_tree_depth].bh)
#define path_leaf_el(_path) ((_path)->p_node[(_path)->p_tree_depth].el)
#define path_num_items(_path) ((_path)->p_tree_depth + 1)

static int ocfs2_find_path(struct inode *inode, struct ocfs2_path *path,
                     u32 cpos);
static void ocfs2_adjust_rightmost_records(struct inode *inode,
                                 handle_t *handle,
                                 struct ocfs2_path *path,
                                 struct ocfs2_extent_rec *insert_rec);
/*
 * Reset the actual path elements so that we can re-use the structure
 * to build another path. Generally, this involves freeing the buffer
 * heads.
 */
static void ocfs2_reinit_path(struct ocfs2_path *path, int keep_root)
{
      int i, start = 0, depth = 0;
      struct ocfs2_path_item *node;

      if (keep_root)
            start = 1;

      for(i = start; i < path_num_items(path); i++) {
            node = &path->p_node[i];

            brelse(node->bh);
            node->bh = NULL;
            node->el = NULL;
      }

      /*
       * Tree depth may change during truncate, or insert. If we're
       * keeping the root extent list, then make sure that our path
       * structure reflects the proper depth.
       */
      if (keep_root)
            depth = le16_to_cpu(path_root_el(path)->l_tree_depth);
      else
            path_root_access(path) = NULL;

      path->p_tree_depth = depth;
}

static void ocfs2_free_path(struct ocfs2_path *path)
{
      if (path) {
            ocfs2_reinit_path(path, 0);
            kfree(path);
      }
}

/*
 * All the elements of src into dest. After this call, src could be freed
 * without affecting dest.
 *
 * Both paths should have the same root. Any non-root elements of dest
 * will be freed.
 */
static void ocfs2_cp_path(struct ocfs2_path *dest, struct ocfs2_path *src)
{
      int i;

      BUG_ON(path_root_bh(dest) != path_root_bh(src));
      BUG_ON(path_root_el(dest) != path_root_el(src));
      BUG_ON(path_root_access(dest) != path_root_access(src));

      ocfs2_reinit_path(dest, 1);

      for(i = 1; i < OCFS2_MAX_PATH_DEPTH; i++) {
            dest->p_node[i].bh = src->p_node[i].bh;
            dest->p_node[i].el = src->p_node[i].el;

            if (dest->p_node[i].bh)
                  get_bh(dest->p_node[i].bh);
      }
}

/*
 * Make the *dest path the same as src and re-initialize src path to
 * have a root only.
 */
static void ocfs2_mv_path(struct ocfs2_path *dest, struct ocfs2_path *src)
{
      int i;

      BUG_ON(path_root_bh(dest) != path_root_bh(src));
      BUG_ON(path_root_access(dest) != path_root_access(src));

      for(i = 1; i < OCFS2_MAX_PATH_DEPTH; i++) {
            brelse(dest->p_node[i].bh);

            dest->p_node[i].bh = src->p_node[i].bh;
            dest->p_node[i].el = src->p_node[i].el;

            src->p_node[i].bh = NULL;
            src->p_node[i].el = NULL;
      }
}

/*
 * Insert an extent block at given index.
 *
 * This will not take an additional reference on eb_bh.
 */
static inline void ocfs2_path_insert_eb(struct ocfs2_path *path, int index,
                              struct buffer_head *eb_bh)
{
      struct ocfs2_extent_block *eb = (struct ocfs2_extent_block *)eb_bh->b_data;

      /*
       * Right now, no root bh is an extent block, so this helps
       * catch code errors with dinode trees. The assertion can be
       * safely removed if we ever need to insert extent block
       * structures at the root.
       */
      BUG_ON(index == 0);

      path->p_node[index].bh = eb_bh;
      path->p_node[index].el = &eb->h_list;
}

static struct ocfs2_path *ocfs2_new_path(struct buffer_head *root_bh,
                               struct ocfs2_extent_list *root_el,
                               ocfs2_journal_access_func access)
{
      struct ocfs2_path *path;

      BUG_ON(le16_to_cpu(root_el->l_tree_depth) >= OCFS2_MAX_PATH_DEPTH);

      path = kzalloc(sizeof(*path), GFP_NOFS);
      if (path) {
            path->p_tree_depth = le16_to_cpu(root_el->l_tree_depth);
            get_bh(root_bh);
            path_root_bh(path) = root_bh;
            path_root_el(path) = root_el;
            path_root_access(path) = access;
      }

      return path;
}

static struct ocfs2_path *ocfs2_new_path_from_path(struct ocfs2_path *path)
{
      return ocfs2_new_path(path_root_bh(path), path_root_el(path),
                        path_root_access(path));
}

static struct ocfs2_path *ocfs2_new_path_from_et(struct ocfs2_extent_tree *et)
{
      return ocfs2_new_path(et->et_root_bh, et->et_root_el,
                        et->et_root_journal_access);
}

/*
 * Journal the buffer at depth idx.  All idx>0 are extent_blocks,
 * otherwise it's the root_access function.
 *
 * I don't like the way this function's name looks next to
 * ocfs2_journal_access_path(), but I don't have a better one.
 */
static int ocfs2_path_bh_journal_access(handle_t *handle,
                              struct inode *inode,
                              struct ocfs2_path *path,
                              int idx)
{
      ocfs2_journal_access_func access = path_root_access(path);

      if (!access)
            access = ocfs2_journal_access;

      if (idx)
            access = ocfs2_journal_access_eb;

      return access(handle, inode, path->p_node[idx].bh,
                  OCFS2_JOURNAL_ACCESS_WRITE);
}

/*
 * Convenience function to journal all components in a path.
 */
static int ocfs2_journal_access_path(struct inode *inode, handle_t *handle,
                             struct ocfs2_path *path)
{
      int i, ret = 0;

      if (!path)
            goto out;

      for(i = 0; i < path_num_items(path); i++) {
            ret = ocfs2_path_bh_journal_access(handle, inode, path, i);
            if (ret < 0) {
                  mlog_errno(ret);
                  goto out;
            }
      }

out:
      return ret;
}

/*
 * Return the index of the extent record which contains cluster #v_cluster.
 * -1 is returned if it was not found.
 *
 * Should work fine on interior and exterior nodes.
 */
int ocfs2_search_extent_list(struct ocfs2_extent_list *el, u32 v_cluster)
{
      int ret = -1;
      int i;
      struct ocfs2_extent_rec *rec;
      u32 rec_end, rec_start, clusters;

      for(i = 0; i < le16_to_cpu(el->l_next_free_rec); i++) {
            rec = &el->l_recs[i];

            rec_start = le32_to_cpu(rec->e_cpos);
            clusters = ocfs2_rec_clusters(el, rec);

            rec_end = rec_start + clusters;

            if (v_cluster >= rec_start && v_cluster < rec_end) {
                  ret = i;
                  break;
            }
      }

      return ret;
}

enum ocfs2_contig_type {
      CONTIG_NONE = 0,
      CONTIG_LEFT,
      CONTIG_RIGHT,
      CONTIG_LEFTRIGHT,
};


/*
 * NOTE: ocfs2_block_extent_contig(), ocfs2_extents_adjacent() and
 * ocfs2_extent_contig only work properly against leaf nodes!
 */
static int ocfs2_block_extent_contig(struct super_block *sb,
                             struct ocfs2_extent_rec *ext,
                             u64 blkno)
{
      u64 blk_end = le64_to_cpu(ext->e_blkno);

      blk_end += ocfs2_clusters_to_blocks(sb,
                            le16_to_cpu(ext->e_leaf_clusters));

      return blkno == blk_end;
}

static int ocfs2_extents_adjacent(struct ocfs2_extent_rec *left,
                          struct ocfs2_extent_rec *right)
{
      u32 left_range;

      left_range = le32_to_cpu(left->e_cpos) +
            le16_to_cpu(left->e_leaf_clusters);

      return (left_range == le32_to_cpu(right->e_cpos));
}

static enum ocfs2_contig_type
      ocfs2_extent_contig(struct inode *inode,
                      struct ocfs2_extent_rec *ext,
                      struct ocfs2_extent_rec *insert_rec)
{
      u64 blkno = le64_to_cpu(insert_rec->e_blkno);

      /*
       * Refuse to coalesce extent records with different flag
       * fields - we don't want to mix unwritten extents with user
       * data.
       */
      if (ext->e_flags != insert_rec->e_flags)
            return CONTIG_NONE;

      if (ocfs2_extents_adjacent(ext, insert_rec) &&
          ocfs2_block_extent_contig(inode->i_sb, ext, blkno))
                  return CONTIG_RIGHT;

      blkno = le64_to_cpu(ext->e_blkno);
      if (ocfs2_extents_adjacent(insert_rec, ext) &&
          ocfs2_block_extent_contig(inode->i_sb, insert_rec, blkno))
            return CONTIG_LEFT;

      return CONTIG_NONE;
}

/*
 * NOTE: We can have pretty much any combination of contiguousness and
 * appending.
 *
 * The usefulness of APPEND_TAIL is more in that it lets us know that
 * we'll have to update the path to that leaf.
 */
enum ocfs2_append_type {
      APPEND_NONE = 0,
      APPEND_TAIL,
};

enum ocfs2_split_type {
      SPLIT_NONE = 0,
      SPLIT_LEFT,
      SPLIT_RIGHT,
};

00785 struct ocfs2_insert_type {
      enum ocfs2_split_type   ins_split;
      enum ocfs2_append_type  ins_appending;
      enum ocfs2_contig_type  ins_contig;
      int               ins_contig_index;
      int               ins_tree_depth;
};

00793 struct ocfs2_merge_ctxt {
      enum ocfs2_contig_type  c_contig_type;
      int               c_has_empty_extent;
      int               c_split_covers_rec;
};

static int ocfs2_validate_extent_block(struct super_block *sb,
                               struct buffer_head *bh)
{
      int rc;
      struct ocfs2_extent_block *eb =
            (struct ocfs2_extent_block *)bh->b_data;

      mlog(0, "Validating extent block %llu\n",
           (unsigned long long)bh->b_blocknr);

      BUG_ON(!buffer_uptodate(bh));

      /*
       * If the ecc fails, we return the error but otherwise
       * leave the filesystem running.  We know any error is
       * local to this block.
       */
      rc = ocfs2_validate_meta_ecc(sb, bh->b_data, &eb->h_check);
      if (rc) {
            mlog(ML_ERROR, "Checksum failed for extent block %llu\n",
                 (unsigned long long)bh->b_blocknr);
            return rc;
      }

      /*
       * Errors after here are fatal.
       */

      if (!OCFS2_IS_VALID_EXTENT_BLOCK(eb)) {
            ocfs2_error(sb,
                      "Extent block #%llu has bad signature %.*s",
                      (unsigned long long)bh->b_blocknr, 7,
                      eb->h_signature);
            return -EINVAL;
      }

      if (le64_to_cpu(eb->h_blkno) != bh->b_blocknr) {
            ocfs2_error(sb,
                      "Extent block #%llu has an invalid h_blkno "
                      "of %llu",
                      (unsigned long long)bh->b_blocknr,
                      (unsigned long long)le64_to_cpu(eb->h_blkno));
            return -EINVAL;
      }

      if (le32_to_cpu(eb->h_fs_generation) != OCFS2_SB(sb)->fs_generation) {
            ocfs2_error(sb,
                      "Extent block #%llu has an invalid "
                      "h_fs_generation of #%u",
                      (unsigned long long)bh->b_blocknr,
                      le32_to_cpu(eb->h_fs_generation));
            return -EINVAL;
      }

      return 0;
}

int ocfs2_read_extent_block(struct inode *inode, u64 eb_blkno,
                      struct buffer_head **bh)
{
      int rc;
      struct buffer_head *tmp = *bh;

      rc = ocfs2_read_block(inode, eb_blkno, &tmp,
                        ocfs2_validate_extent_block);

      /* If ocfs2_read_block() got us a new bh, pass it up. */
      if (!rc && !*bh)
            *bh = tmp;

      return rc;
}


/*
 * How many free extents have we got before we need more meta data?
 */
int ocfs2_num_free_extents(struct ocfs2_super *osb,
                     struct inode *inode,
                     struct ocfs2_extent_tree *et)
{
      int retval;
      struct ocfs2_extent_list *el = NULL;
      struct ocfs2_extent_block *eb;
      struct buffer_head *eb_bh = NULL;
      u64 last_eb_blk = 0;

      mlog_entry_void();

      el = et->et_root_el;
      last_eb_blk = ocfs2_et_get_last_eb_blk(et);

      if (last_eb_blk) {
            retval = ocfs2_read_extent_block(inode, last_eb_blk, &eb_bh);
            if (retval < 0) {
                  mlog_errno(retval);
                  goto bail;
            }
            eb = (struct ocfs2_extent_block *) eb_bh->b_data;
            el = &eb->h_list;
      }

      BUG_ON(el->l_tree_depth != 0);

      retval = le16_to_cpu(el->l_count) - le16_to_cpu(el->l_next_free_rec);
bail:
      brelse(eb_bh);

      mlog_exit(retval);
      return retval;
}

/* expects array to already be allocated
 *
 * sets h_signature, h_blkno, h_suballoc_bit, h_suballoc_slot, and
 * l_count for you
 */
static int ocfs2_create_new_meta_bhs(struct ocfs2_super *osb,
                             handle_t *handle,
                             struct inode *inode,
                             int wanted,
                             struct ocfs2_alloc_context *meta_ac,
                             struct buffer_head *bhs[])
{
      int count, status, i;
      u16 suballoc_bit_start;
      u32 num_got;
      u64 first_blkno;
      struct ocfs2_extent_block *eb;

      mlog_entry_void();

      count = 0;
      while (count < wanted) {
            status = ocfs2_claim_metadata(osb,
                                    handle,
                                    meta_ac,
                                    wanted - count,
                                    &suballoc_bit_start,
                                    &num_got,
                                    &first_blkno);
            if (status < 0) {
                  mlog_errno(status);
                  goto bail;
            }

            for(i = count;  i < (num_got + count); i++) {
                  bhs[i] = sb_getblk(osb->sb, first_blkno);
                  if (bhs[i] == NULL) {
                        status = -EIO;
                        mlog_errno(status);
                        goto bail;
                  }
                  ocfs2_set_new_buffer_uptodate(inode, bhs[i]);

                  status = ocfs2_journal_access_eb(handle, inode, bhs[i],
                                           OCFS2_JOURNAL_ACCESS_CREATE);
                  if (status < 0) {
                        mlog_errno(status);
                        goto bail;
                  }

                  memset(bhs[i]->b_data, 0, osb->sb->s_blocksize);
                  eb = (struct ocfs2_extent_block *) bhs[i]->b_data;
                  /* Ok, setup the minimal stuff here. */
                  strcpy(eb->h_signature, OCFS2_EXTENT_BLOCK_SIGNATURE);
                  eb->h_blkno = cpu_to_le64(first_blkno);
                  eb->h_fs_generation = cpu_to_le32(osb->fs_generation);
                  eb->h_suballoc_slot = cpu_to_le16(osb->slot_num);
                  eb->h_suballoc_bit = cpu_to_le16(suballoc_bit_start);
                  eb->h_list.l_count =
                        cpu_to_le16(ocfs2_extent_recs_per_eb(osb->sb));

                  suballoc_bit_start++;
                  first_blkno++;

                  /* We'll also be dirtied by the caller, so
                   * this isn't absolutely necessary. */
                  status = ocfs2_journal_dirty(handle, bhs[i]);
                  if (status < 0) {
                        mlog_errno(status);
                        goto bail;
                  }
            }

            count += num_got;
      }

      status = 0;
bail:
      if (status < 0) {
            for(i = 0; i < wanted; i++) {
                  brelse(bhs[i]);
                  bhs[i] = NULL;
            }
      }
      mlog_exit(status);
      return status;
}

/*
 * Helper function for ocfs2_add_branch() and ocfs2_shift_tree_depth().
 *
 * Returns the sum of the rightmost extent rec logical offset and
 * cluster count.
 *
 * ocfs2_add_branch() uses this to determine what logical cluster
 * value should be populated into the leftmost new branch records.
 *
 * ocfs2_shift_tree_depth() uses this to determine the # clusters
 * value for the new topmost tree record.
 */
static inline u32 ocfs2_sum_rightmost_rec(struct ocfs2_extent_list  *el)
{
      int i;

      i = le16_to_cpu(el->l_next_free_rec) - 1;

      return le32_to_cpu(el->l_recs[i].e_cpos) +
            ocfs2_rec_clusters(el, &el->l_recs[i]);
}

/*
 * Change range of the branches in the right most path according to the leaf
 * extent block's rightmost record.
 */
static int ocfs2_adjust_rightmost_branch(handle_t *handle,
                               struct inode *inode,
                               struct ocfs2_extent_tree *et)
{
      int status;
      struct ocfs2_path *path = NULL;
      struct ocfs2_extent_list *el;
      struct ocfs2_extent_rec *rec;

      path = ocfs2_new_path_from_et(et);
      if (!path) {
            status = -ENOMEM;
            return status;
      }

      status = ocfs2_find_path(inode, path, UINT_MAX);
      if (status < 0) {
            mlog_errno(status);
            goto out;
      }

      status = ocfs2_extend_trans(handle, path_num_items(path) +
                            handle->h_buffer_credits);
      if (status < 0) {
            mlog_errno(status);
            goto out;
      }

      status = ocfs2_journal_access_path(inode, handle, path);
      if (status < 0) {
            mlog_errno(status);
            goto out;
      }

      el = path_leaf_el(path);
      rec = &el->l_recs[le32_to_cpu(el->l_next_free_rec) - 1];

      ocfs2_adjust_rightmost_records(inode, handle, path, rec);

out:
      ocfs2_free_path(path);
      return status;
}

/*
 * Add an entire tree branch to our inode. eb_bh is the extent block
 * to start at, if we don't want to start the branch at the dinode
 * structure.
 *
 * last_eb_bh is required as we have to update it's next_leaf pointer
 * for the new last extent block.
 *
 * the new branch will be 'empty' in the sense that every block will
 * contain a single record with cluster count == 0.
 */
static int ocfs2_add_branch(struct ocfs2_super *osb,
                      handle_t *handle,
                      struct inode *inode,
                      struct ocfs2_extent_tree *et,
                      struct buffer_head *eb_bh,
                      struct buffer_head **last_eb_bh,
                      struct ocfs2_alloc_context *meta_ac)
{
      int status, new_blocks, i;
      u64 next_blkno, new_last_eb_blk;
      struct buffer_head *bh;
      struct buffer_head **new_eb_bhs = NULL;
      struct ocfs2_extent_block *eb;
      struct ocfs2_extent_list  *eb_el;
      struct ocfs2_extent_list  *el;
      u32 new_cpos, root_end;

      mlog_entry_void();

      BUG_ON(!last_eb_bh || !*last_eb_bh);

      if (eb_bh) {
            eb = (struct ocfs2_extent_block *) eb_bh->b_data;
            el = &eb->h_list;
      } else
            el = et->et_root_el;

      /* we never add a branch to a leaf. */
      BUG_ON(!el->l_tree_depth);

      new_blocks = le16_to_cpu(el->l_tree_depth);

      eb = (struct ocfs2_extent_block *)(*last_eb_bh)->b_data;
      new_cpos = ocfs2_sum_rightmost_rec(&eb->h_list);
      root_end = ocfs2_sum_rightmost_rec(et->et_root_el);

      /*
       * If there is a gap before the root end and the real end
       * of the righmost leaf block, we need to remove the gap
       * between new_cpos and root_end first so that the tree
       * is consistent after we add a new branch(it will start
       * from new_cpos).
       */
      if (root_end > new_cpos) {
            mlog(0, "adjust the cluster end from %u to %u\n",
                 root_end, new_cpos);
            status = ocfs2_adjust_rightmost_branch(handle, inode, et);
            if (status) {
                  mlog_errno(status);
                  goto bail;
            }
      }

      /* allocate the number of new eb blocks we need */
      new_eb_bhs = kcalloc(new_blocks, sizeof(struct buffer_head *),
                       GFP_KERNEL);
      if (!new_eb_bhs) {
            status = -ENOMEM;
            mlog_errno(status);
            goto bail;
      }

      status = ocfs2_create_new_meta_bhs(osb, handle, inode, new_blocks,
                                 meta_ac, new_eb_bhs);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

      /* Note: new_eb_bhs[new_blocks - 1] is the guy which will be
       * linked with the rest of the tree.
       * conversly, new_eb_bhs[0] is the new bottommost leaf.
       *
       * when we leave the loop, new_last_eb_blk will point to the
       * newest leaf, and next_blkno will point to the topmost extent
       * block. */
      next_blkno = new_last_eb_blk = 0;
      for(i = 0; i < new_blocks; i++) {
            bh = new_eb_bhs[i];
            eb = (struct ocfs2_extent_block *) bh->b_data;
            /* ocfs2_create_new_meta_bhs() should create it right! */
            BUG_ON(!OCFS2_IS_VALID_EXTENT_BLOCK(eb));
            eb_el = &eb->h_list;

            status = ocfs2_journal_access_eb(handle, inode, bh,
                                     OCFS2_JOURNAL_ACCESS_CREATE);
            if (status < 0) {
                  mlog_errno(status);
                  goto bail;
            }

            eb->h_next_leaf_blk = 0;
            eb_el->l_tree_depth = cpu_to_le16(i);
            eb_el->l_next_free_rec = cpu_to_le16(1);
            /*
             * This actually counts as an empty extent as
             * c_clusters == 0
             */
            eb_el->l_recs[0].e_cpos = cpu_to_le32(new_cpos);
            eb_el->l_recs[0].e_blkno = cpu_to_le64(next_blkno);
            /*
             * eb_el isn't always an interior node, but even leaf
             * nodes want a zero'd flags and reserved field so
             * this gets the whole 32 bits regardless of use.
             */
            eb_el->l_recs[0].e_int_clusters = cpu_to_le32(0);
            if (!eb_el->l_tree_depth)
                  new_last_eb_blk = le64_to_cpu(eb->h_blkno);

            status = ocfs2_journal_dirty(handle, bh);
            if (status < 0) {
                  mlog_errno(status);
                  goto bail;
            }

            next_blkno = le64_to_cpu(eb->h_blkno);
      }

      /* This is a bit hairy. We want to update up to three blocks
       * here without leaving any of them in an inconsistent state
       * in case of error. We don't have to worry about
       * journal_dirty erroring as it won't unless we've aborted the
       * handle (in which case we would never be here) so reserving
       * the write with journal_access is all we need to do. */
      status = ocfs2_journal_access_eb(handle, inode, *last_eb_bh,
                               OCFS2_JOURNAL_ACCESS_WRITE);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }
      status = ocfs2_et_root_journal_access(handle, inode, et,
                                    OCFS2_JOURNAL_ACCESS_WRITE);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }
      if (eb_bh) {
            status = ocfs2_journal_access_eb(handle, inode, eb_bh,
                                     OCFS2_JOURNAL_ACCESS_WRITE);
            if (status < 0) {
                  mlog_errno(status);
                  goto bail;
            }
      }

      /* Link the new branch into the rest of the tree (el will
       * either be on the root_bh, or the extent block passed in. */
      i = le16_to_cpu(el->l_next_free_rec);
      el->l_recs[i].e_blkno = cpu_to_le64(next_blkno);
      el->l_recs[i].e_cpos = cpu_to_le32(new_cpos);
      el->l_recs[i].e_int_clusters = 0;
      le16_add_cpu(&el->l_next_free_rec, 1);

      /* fe needs a new last extent block pointer, as does the
       * next_leaf on the previously last-extent-block. */
      ocfs2_et_set_last_eb_blk(et, new_last_eb_blk);

      eb = (struct ocfs2_extent_block *) (*last_eb_bh)->b_data;
      eb->h_next_leaf_blk = cpu_to_le64(new_last_eb_blk);

      status = ocfs2_journal_dirty(handle, *last_eb_bh);
      if (status < 0)
            mlog_errno(status);
      status = ocfs2_journal_dirty(handle, et->et_root_bh);
      if (status < 0)
            mlog_errno(status);
      if (eb_bh) {
            status = ocfs2_journal_dirty(handle, eb_bh);
            if (status < 0)
                  mlog_errno(status);
      }

      /*
       * Some callers want to track the rightmost leaf so pass it
       * back here.
       */
      brelse(*last_eb_bh);
      get_bh(new_eb_bhs[0]);
      *last_eb_bh = new_eb_bhs[0];

      status = 0;
bail:
      if (new_eb_bhs) {
            for (i = 0; i < new_blocks; i++)
                  brelse(new_eb_bhs[i]);
            kfree(new_eb_bhs);
      }

      mlog_exit(status);
      return status;
}

/*
 * adds another level to the allocation tree.
 * returns back the new extent block so you can add a branch to it
 * after this call.
 */
static int ocfs2_shift_tree_depth(struct ocfs2_super *osb,
                          handle_t *handle,
                          struct inode *inode,
                          struct ocfs2_extent_tree *et,
                          struct ocfs2_alloc_context *meta_ac,
                          struct buffer_head **ret_new_eb_bh)
{
      int status, i;
      u32 new_clusters;
      struct buffer_head *new_eb_bh = NULL;
      struct ocfs2_extent_block *eb;
      struct ocfs2_extent_list  *root_el;
      struct ocfs2_extent_list  *eb_el;

      mlog_entry_void();

      status = ocfs2_create_new_meta_bhs(osb, handle, inode, 1, meta_ac,
                                 &new_eb_bh);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

      eb = (struct ocfs2_extent_block *) new_eb_bh->b_data;
      /* ocfs2_create_new_meta_bhs() should create it right! */
      BUG_ON(!OCFS2_IS_VALID_EXTENT_BLOCK(eb));

      eb_el = &eb->h_list;
      root_el = et->et_root_el;

      status = ocfs2_journal_access_eb(handle, inode, new_eb_bh,
                               OCFS2_JOURNAL_ACCESS_CREATE);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

      /* copy the root extent list data into the new extent block */
      eb_el->l_tree_depth = root_el->l_tree_depth;
      eb_el->l_next_free_rec = root_el->l_next_free_rec;
      for (i = 0; i < le16_to_cpu(root_el->l_next_free_rec); i++)
            eb_el->l_recs[i] = root_el->l_recs[i];

      status = ocfs2_journal_dirty(handle, new_eb_bh);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

      status = ocfs2_et_root_journal_access(handle, inode, et,
                                    OCFS2_JOURNAL_ACCESS_WRITE);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

      new_clusters = ocfs2_sum_rightmost_rec(eb_el);

      /* update root_bh now */
      le16_add_cpu(&root_el->l_tree_depth, 1);
      root_el->l_recs[0].e_cpos = 0;
      root_el->l_recs[0].e_blkno = eb->h_blkno;
      root_el->l_recs[0].e_int_clusters = cpu_to_le32(new_clusters);
      for (i = 1; i < le16_to_cpu(root_el->l_next_free_rec); i++)
            memset(&root_el->l_recs[i], 0, sizeof(struct ocfs2_extent_rec));
      root_el->l_next_free_rec = cpu_to_le16(1);

      /* If this is our 1st tree depth shift, then last_eb_blk
       * becomes the allocated extent block */
      if (root_el->l_tree_depth == cpu_to_le16(1))
            ocfs2_et_set_last_eb_blk(et, le64_to_cpu(eb->h_blkno));

      status = ocfs2_journal_dirty(handle, et->et_root_bh);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

      *ret_new_eb_bh = new_eb_bh;
      new_eb_bh = NULL;
      status = 0;
bail:
      brelse(new_eb_bh);

      mlog_exit(status);
      return status;
}

/*
 * Should only be called when there is no space left in any of the
 * leaf nodes. What we want to do is find the lowest tree depth
 * non-leaf extent block with room for new records. There are three
 * valid results of this search:
 *
 * 1) a lowest extent block is found, then we pass it back in
 *    *lowest_eb_bh and return '0'
 *
 * 2) the search fails to find anything, but the root_el has room. We
 *    pass NULL back in *lowest_eb_bh, but still return '0'
 *
 * 3) the search fails to find anything AND the root_el is full, in
 *    which case we return > 0
 *
 * return status < 0 indicates an error.
 */
static int ocfs2_find_branch_target(struct ocfs2_super *osb,
                            struct inode *inode,
                            struct ocfs2_extent_tree *et,
                            struct buffer_head **target_bh)
{
      int status = 0, i;
      u64 blkno;
      struct ocfs2_extent_block *eb;
      struct ocfs2_extent_list  *el;
      struct buffer_head *bh = NULL;
      struct buffer_head *lowest_bh = NULL;

      mlog_entry_void();

      *target_bh = NULL;

      el = et->et_root_el;

      while(le16_to_cpu(el->l_tree_depth) > 1) {
            if (le16_to_cpu(el->l_next_free_rec) == 0) {
                  ocfs2_error(inode->i_sb, "Dinode %llu has empty "
                            "extent list (next_free_rec == 0)",
                            (unsigned long long)OCFS2_I(inode)->ip_blkno);
                  status = -EIO;
                  goto bail;
            }
            i = le16_to_cpu(el->l_next_free_rec) - 1;
            blkno = le64_to_cpu(el->l_recs[i].e_blkno);
            if (!blkno) {
                  ocfs2_error(inode->i_sb, "Dinode %llu has extent "
                            "list where extent # %d has no physical "
                            "block start",
                            (unsigned long long)OCFS2_I(inode)->ip_blkno, i);
                  status = -EIO;
                  goto bail;
            }

            brelse(bh);
            bh = NULL;

            status = ocfs2_read_extent_block(inode, blkno, &bh);
            if (status < 0) {
                  mlog_errno(status);
                  goto bail;
            }

            eb = (struct ocfs2_extent_block *) bh->b_data;
            el = &eb->h_list;

            if (le16_to_cpu(el->l_next_free_rec) <
                le16_to_cpu(el->l_count)) {
                  brelse(lowest_bh);
                  lowest_bh = bh;
                  get_bh(lowest_bh);
            }
      }

      /* If we didn't find one and the fe doesn't have any room,
       * then return '1' */
      el = et->et_root_el;
      if (!lowest_bh && (el->l_next_free_rec == el->l_count))
            status = 1;

      *target_bh = lowest_bh;
bail:
      brelse(bh);

      mlog_exit(status);
      return status;
}

/*
 * Grow a b-tree so that it has more records.
 *
 * We might shift the tree depth in which case existing paths should
 * be considered invalid.
 *
 * Tree depth after the grow is returned via *final_depth.
 *
 * *last_eb_bh will be updated by ocfs2_add_branch().
 */
static int ocfs2_grow_tree(struct inode *inode, handle_t *handle,
                     struct ocfs2_extent_tree *et, int *final_depth,
                     struct buffer_head **last_eb_bh,
                     struct ocfs2_alloc_context *meta_ac)
{
      int ret, shift;
      struct ocfs2_extent_list *el = et->et_root_el;
      int depth = le16_to_cpu(el->l_tree_depth);
      struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
      struct buffer_head *bh = NULL;

      BUG_ON(meta_ac == NULL);

      shift = ocfs2_find_branch_target(osb, inode, et, &bh);
      if (shift < 0) {
            ret = shift;
            mlog_errno(ret);
            goto out;
      }

      /* We traveled all the way to the bottom of the allocation tree
       * and didn't find room for any more extents - we need to add
       * another tree level */
      if (shift) {
            BUG_ON(bh);
            mlog(0, "need to shift tree depth (current = %d)\n", depth);

            /* ocfs2_shift_tree_depth will return us a buffer with
             * the new extent block (so we can pass that to
             * ocfs2_add_branch). */
            ret = ocfs2_shift_tree_depth(osb, handle, inode, et,
                                   meta_ac, &bh);
            if (ret < 0) {
                  mlog_errno(ret);
                  goto out;
            }
            depth++;
            if (depth == 1) {
                  /*
                   * Special case: we have room now if we shifted from
                   * tree_depth 0, so no more work needs to be done.
                   *
                   * We won't be calling add_branch, so pass
                   * back *last_eb_bh as the new leaf. At depth
                   * zero, it should always be null so there's
                   * no reason to brelse.
                   */
                  BUG_ON(*last_eb_bh);
                  get_bh(bh);
                  *last_eb_bh = bh;
                  goto out;
            }
      }

      /* call ocfs2_add_branch to add the final part of the tree with
       * the new data. */
      mlog(0, "add branch. bh = %p\n", bh);
      ret = ocfs2_add_branch(osb, handle, inode, et, bh, last_eb_bh,
                         meta_ac);
      if (ret < 0) {
            mlog_errno(ret);
            goto out;
      }

out:
      if (final_depth)
            *final_depth = depth;
      brelse(bh);
      return ret;
}

/*
 * This function will discard the rightmost extent record.
 */
static void ocfs2_shift_records_right(struct ocfs2_extent_list *el)
{
      int next_free = le16_to_cpu(el->l_next_free_rec);
      int count = le16_to_cpu(el->l_count);
      unsigned int num_bytes;

      BUG_ON(!next_free);
      /* This will cause us to go off the end of our extent list. */
      BUG_ON(next_free >= count);

      num_bytes = sizeof(struct ocfs2_extent_rec) * next_free;

      memmove(&el->l_recs[1], &el->l_recs[0], num_bytes);
}

static void ocfs2_rotate_leaf(struct ocfs2_extent_list *el,
                        struct ocfs2_extent_rec *insert_rec)
{
      int i, insert_index, next_free, has_empty, num_bytes;
      u32 insert_cpos = le32_to_cpu(insert_rec->e_cpos);
      struct ocfs2_extent_rec *rec;

      next_free = le16_to_cpu(el->l_next_free_rec);
      has_empty = ocfs2_is_empty_extent(&el->l_recs[0]);

      BUG_ON(!next_free);

      /* The tree code before us didn't allow enough room in the leaf. */
      BUG_ON(el->l_next_free_rec == el->l_count && !has_empty);

      /*
       * The easiest way to approach this is to just remove the
       * empty extent and temporarily decrement next_free.
       */
      if (has_empty) {
            /*
             * If next_free was 1 (only an empty extent), this
             * loop won't execute, which is fine. We still want
             * the decrement above to happen.
             */
            for(i = 0; i < (next_free - 1); i++)
                  el->l_recs[i] = el->l_recs[i+1];

            next_free--;
      }

      /*
       * Figure out what the new record index should be.
       */
      for(i = 0; i < next_free; i++) {
            rec = &el->l_recs[i];

            if (insert_cpos < le32_to_cpu(rec->e_cpos))
                  break;
      }
      insert_index = i;

      mlog(0, "ins %u: index %d, has_empty %d, next_free %d, count %d\n",
           insert_cpos, insert_index, has_empty, next_free, le16_to_cpu(el->l_count));

      BUG_ON(insert_index < 0);
      BUG_ON(insert_index >= le16_to_cpu(el->l_count));
      BUG_ON(insert_index > next_free);

      /*
       * No need to memmove if we're just adding to the tail.
       */
      if (insert_index != next_free) {
            BUG_ON(next_free >= le16_to_cpu(el->l_count));

            num_bytes = next_free - insert_index;
            num_bytes *= sizeof(struct ocfs2_extent_rec);
            memmove(&el->l_recs[insert_index + 1],
                  &el->l_recs[insert_index],
                  num_bytes);
      }

      /*
       * Either we had an empty extent, and need to re-increment or
       * there was no empty extent on a non full rightmost leaf node,
       * in which case we still need to increment.
       */
      next_free++;
      el->l_next_free_rec = cpu_to_le16(next_free);
      /*
       * Make sure none of the math above just messed up our tree.
       */
      BUG_ON(le16_to_cpu(el->l_next_free_rec) > le16_to_cpu(el->l_count));

      el->l_recs[insert_index] = *insert_rec;

}

static void ocfs2_remove_empty_extent(struct ocfs2_extent_list *el)
{
      int size, num_recs = le16_to_cpu(el->l_next_free_rec);

      BUG_ON(num_recs == 0);

      if (ocfs2_is_empty_extent(&el->l_recs[0])) {
            num_recs--;
            size = num_recs * sizeof(struct ocfs2_extent_rec);
            memmove(&el->l_recs[0], &el->l_recs[1], size);
            memset(&el->l_recs[num_recs], 0,
                   sizeof(struct ocfs2_extent_rec));
            el->l_next_free_rec = cpu_to_le16(num_recs);
      }
}

/*
 * Create an empty extent record .
 *
 * l_next_free_rec may be updated.
 *
 * If an empty extent already exists do nothing.
 */
static void ocfs2_create_empty_extent(struct ocfs2_extent_list *el)
{
      int next_free = le16_to_cpu(el->l_next_free_rec);

      BUG_ON(le16_to_cpu(el->l_tree_depth) != 0);

      if (next_free == 0)
            goto set_and_inc;

      if (ocfs2_is_empty_extent(&el->l_recs[0]))
            return;

      mlog_bug_on_msg(el->l_count == el->l_next_free_rec,
                  "Asked to create an empty extent in a full list:\n"
                  "count = %u, tree depth = %u",
                  le16_to_cpu(el->l_count),
                  le16_to_cpu(el->l_tree_depth));

      ocfs2_shift_records_right(el);

set_and_inc:
      le16_add_cpu(&el->l_next_free_rec, 1);
      memset(&el->l_recs[0], 0, sizeof(struct ocfs2_extent_rec));
}

/*
 * For a rotation which involves two leaf nodes, the "root node" is
 * the lowest level tree node which contains a path to both leafs. This
 * resulting set of information can be used to form a complete "subtree"
 *
 * This function is passed two full paths from the dinode down to a
 * pair of adjacent leaves. It's task is to figure out which path
 * index contains the subtree root - this can be the root index itself
 * in a worst-case rotation.
 *
 * The array index of the subtree root is passed back.
 */
static int ocfs2_find_subtree_root(struct inode *inode,
                           struct ocfs2_path *left,
                           struct ocfs2_path *right)
{
      int i = 0;

      /*
       * Check that the caller passed in two paths from the same tree.
       */
      BUG_ON(path_root_bh(left) != path_root_bh(right));

      do {
            i++;

            /*
             * The caller didn't pass two adjacent paths.
             */
            mlog_bug_on_msg(i > left->p_tree_depth,
                        "Inode %lu, left depth %u, right depth %u\n"
                        "left leaf blk %llu, right leaf blk %llu\n",
                        inode->i_ino, left->p_tree_depth,
                        right->p_tree_depth,
                        (unsigned long long)path_leaf_bh(left)->b_blocknr,
                        (unsigned long long)path_leaf_bh(right)->b_blocknr);
      } while (left->p_node[i].bh->b_blocknr ==
             right->p_node[i].bh->b_blocknr);

      return i - 1;
}

typedef void (path_insert_t)(void *, struct buffer_head *);

/*
 * Traverse a btree path in search of cpos, starting at root_el.
 *
 * This code can be called with a cpos larger than the tree, in which
 * case it will return the rightmost path.
 */
static int __ocfs2_find_path(struct inode *inode,
                       struct ocfs2_extent_list *root_el, u32 cpos,
                       path_insert_t *func, void *data)
{
      int i, ret = 0;
      u32 range;
      u64 blkno;
      struct buffer_head *bh = NULL;
      struct ocfs2_extent_block *eb;
      struct ocfs2_extent_list *el;
      struct ocfs2_extent_rec *rec;
      struct ocfs2_inode_info *oi = OCFS2_I(inode);

      el = root_el;
      while (el->l_tree_depth) {
            if (le16_to_cpu(el->l_next_free_rec) == 0) {
                  ocfs2_error(inode->i_sb,
                            "Inode %llu has empty extent list at "
                            "depth %u\n",
                            (unsigned long long)oi->ip_blkno,
                            le16_to_cpu(el->l_tree_depth));
                  ret = -EROFS;
                  goto out;

            }

            for(i = 0; i < le16_to_cpu(el->l_next_free_rec) - 1; i++) {
                  rec = &el->l_recs[i];

                  /*
                   * In the case that cpos is off the allocation
                   * tree, this should just wind up returning the
                   * rightmost record.
                   */
                  range = le32_to_cpu(rec->e_cpos) +
                        ocfs2_rec_clusters(el, rec);
                  if (cpos >= le32_to_cpu(rec->e_cpos) && cpos < range)
                      break;
            }

            blkno = le64_to_cpu(el->l_recs[i].e_blkno);
            if (blkno == 0) {
                  ocfs2_error(inode->i_sb,
                            "Inode %llu has bad blkno in extent list "
                            "at depth %u (index %d)\n",
                            (unsigned long long)oi->ip_blkno,
                            le16_to_cpu(el->l_tree_depth), i);
                  ret = -EROFS;
                  goto out;
            }

            brelse(bh);
            bh = NULL;
            ret = ocfs2_read_extent_block(inode, blkno, &bh);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            eb = (struct ocfs2_extent_block *) bh->b_data;
            el = &eb->h_list;

            if (le16_to_cpu(el->l_next_free_rec) >
                le16_to_cpu(el->l_count)) {
                  ocfs2_error(inode->i_sb,
                            "Inode %llu has bad count in extent list "
                            "at block %llu (next free=%u, count=%u)\n",
                            (unsigned long long)oi->ip_blkno,
                            (unsigned long long)bh->b_blocknr,
                            le16_to_cpu(el->l_next_free_rec),
                            le16_to_cpu(el->l_count));
                  ret = -EROFS;
                  goto out;
            }

            if (func)
                  func(data, bh);
      }

out:
      /*
       * Catch any trailing bh that the loop didn't handle.
       */
      brelse(bh);

      return ret;
}

/*
 * Given an initialized path (that is, it has a valid root extent
 * list), this function will traverse the btree in search of the path
 * which would contain cpos.
 *
 * The path traveled is recorded in the path structure.
 *
 * Note that this will not do any comparisons on leaf node extent
 * records, so it will work fine in the case that we just added a tree
 * branch.
 */
01827 struct find_path_data {
      int index;
      struct ocfs2_path *path;
};
static void find_path_ins(void *data, struct buffer_head *bh)
{
      struct find_path_data *fp = data;

      get_bh(bh);
      ocfs2_path_insert_eb(fp->path, fp->index, bh);
      fp->index++;
}
static int ocfs2_find_path(struct inode *inode, struct ocfs2_path *path,
                     u32 cpos)
{
      struct find_path_data data;

      data.index = 1;
      data.path = path;
      return __ocfs2_find_path(inode, path_root_el(path), cpos,
                         find_path_ins, &data);
}

static void find_leaf_ins(void *data, struct buffer_head *bh)
{
      struct ocfs2_extent_block *eb =(struct ocfs2_extent_block *)bh->b_data;
      struct ocfs2_extent_list *el = &eb->h_list;
      struct buffer_head **ret = data;

      /* We want to retain only the leaf block. */
      if (le16_to_cpu(el->l_tree_depth) == 0) {
            get_bh(bh);
            *ret = bh;
      }
}
/*
 * Find the leaf block in the tree which would contain cpos. No
 * checking of the actual leaf is done.
 *
 * Some paths want to call this instead of allocating a path structure
 * and calling ocfs2_find_path().
 *
 * This function doesn't handle non btree extent lists.
 */
int ocfs2_find_leaf(struct inode *inode, struct ocfs2_extent_list *root_el,
                u32 cpos, struct buffer_head **leaf_bh)
{
      int ret;
      struct buffer_head *bh = NULL;

      ret = __ocfs2_find_path(inode, root_el, cpos, find_leaf_ins, &bh);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      *leaf_bh = bh;
out:
      return ret;
}

/*
 * Adjust the adjacent records (left_rec, right_rec) involved in a rotation.
 *
 * Basically, we've moved stuff around at the bottom of the tree and
 * we need to fix up the extent records above the changes to reflect
 * the new changes.
 *
 * left_rec: the record on the left.
 * left_child_el: is the child list pointed to by left_rec
 * right_rec: the record to the right of left_rec
 * right_child_el: is the child list pointed to by right_rec
 *
 * By definition, this only works on interior nodes.
 */
static void ocfs2_adjust_adjacent_records(struct ocfs2_extent_rec *left_rec,
                          struct ocfs2_extent_list *left_child_el,
                          struct ocfs2_extent_rec *right_rec,
                          struct ocfs2_extent_list *right_child_el)
{
      u32 left_clusters, right_end;

      /*
       * Interior nodes never have holes. Their cpos is the cpos of
       * the leftmost record in their child list. Their cluster
       * count covers the full theoretical range of their child list
       * - the range between their cpos and the cpos of the record
       * immediately to their right.
       */
      left_clusters = le32_to_cpu(right_child_el->l_recs[0].e_cpos);
      if (!ocfs2_rec_clusters(right_child_el, &right_child_el->l_recs[0])) {
            BUG_ON(right_child_el->l_tree_depth);
            BUG_ON(le16_to_cpu(right_child_el->l_next_free_rec) <= 1);
            left_clusters = le32_to_cpu(right_child_el->l_recs[1].e_cpos);
      }
      left_clusters -= le32_to_cpu(left_rec->e_cpos);
      left_rec->e_int_clusters = cpu_to_le32(left_clusters);

      /*
       * Calculate the rightmost cluster count boundary before
       * moving cpos - we will need to adjust clusters after
       * updating e_cpos to keep the same highest cluster count.
       */
      right_end = le32_to_cpu(right_rec->e_cpos);
      right_end += le32_to_cpu(right_rec->e_int_clusters);

      right_rec->e_cpos = left_rec->e_cpos;
      le32_add_cpu(&right_rec->e_cpos, left_clusters);

      right_end -= le32_to_cpu(right_rec->e_cpos);
      right_rec->e_int_clusters = cpu_to_le32(right_end);
}

/*
 * Adjust the adjacent root node records involved in a
 * rotation. left_el_blkno is passed in as a key so that we can easily
 * find it's index in the root list.
 */
static void ocfs2_adjust_root_records(struct ocfs2_extent_list *root_el,
                              struct ocfs2_extent_list *left_el,
                              struct ocfs2_extent_list *right_el,
                              u64 left_el_blkno)
{
      int i;

      BUG_ON(le16_to_cpu(root_el->l_tree_depth) <=
             le16_to_cpu(left_el->l_tree_depth));

      for(i = 0; i < le16_to_cpu(root_el->l_next_free_rec) - 1; i++) {
            if (le64_to_cpu(root_el->l_recs[i].e_blkno) == left_el_blkno)
                  break;
      }

      /*
       * The path walking code should have never returned a root and
       * two paths which are not adjacent.
       */
      BUG_ON(i >= (le16_to_cpu(root_el->l_next_free_rec) - 1));

      ocfs2_adjust_adjacent_records(&root_el->l_recs[i], left_el,
                              &root_el->l_recs[i + 1], right_el);
}

/*
 * We've changed a leaf block (in right_path) and need to reflect that
 * change back up the subtree.
 *
 * This happens in multiple places:
 *   - When we've moved an extent record from the left path leaf to the right
 *     path leaf to make room for an empty extent in the left path leaf.
 *   - When our insert into the right path leaf is at the leftmost edge
 *     and requires an update of the path immediately to it's left. This
 *     can occur at the end of some types of rotation and appending inserts.
 *   - When we've adjusted the last extent record in the left path leaf and the
 *     1st extent record in the right path leaf during cross extent block merge.
 */
static void ocfs2_complete_edge_insert(struct inode *inode, handle_t *handle,
                               struct ocfs2_path *left_path,
                               struct ocfs2_path *right_path,
                               int subtree_index)
{
      int ret, i, idx;
      struct ocfs2_extent_list *el, *left_el, *right_el;
      struct ocfs2_extent_rec *left_rec, *right_rec;
      struct buffer_head *root_bh = left_path->p_node[subtree_index].bh;

      /*
       * Update the counts and position values within all the
       * interior nodes to reflect the leaf rotation we just did.
       *
       * The root node is handled below the loop.
       *
       * We begin the loop with right_el and left_el pointing to the
       * leaf lists and work our way up.
       *
       * NOTE: within this loop, left_el and right_el always refer
       * to the *child* lists.
       */
      left_el = path_leaf_el(left_path);
      right_el = path_leaf_el(right_path);
      for(i = left_path->p_tree_depth - 1; i > subtree_index; i--) {
            mlog(0, "Adjust records at index %u\n", i);

            /*
             * One nice property of knowing that all of these
             * nodes are below the root is that we only deal with
             * the leftmost right node record and the rightmost
             * left node record.
             */
            el = left_path->p_node[i].el;
            idx = le16_to_cpu(left_el->l_next_free_rec) - 1;
            left_rec = &el->l_recs[idx];

            el = right_path->p_node[i].el;
            right_rec = &el->l_recs[0];

            ocfs2_adjust_adjacent_records(left_rec, left_el, right_rec,
                                    right_el);

            ret = ocfs2_journal_dirty(handle, left_path->p_node[i].bh);
            if (ret)
                  mlog_errno(ret);

            ret = ocfs2_journal_dirty(handle, right_path->p_node[i].bh);
            if (ret)
                  mlog_errno(ret);

            /*
             * Setup our list pointers now so that the current
             * parents become children in the next iteration.
             */
            left_el = left_path->p_node[i].el;
            right_el = right_path->p_node[i].el;
      }

      /*
       * At the root node, adjust the two adjacent records which
       * begin our path to the leaves.
       */

      el = left_path->p_node[subtree_index].el;
      left_el = left_path->p_node[subtree_index + 1].el;
      right_el = right_path->p_node[subtree_index + 1].el;

      ocfs2_adjust_root_records(el, left_el, right_el,
                          left_path->p_node[subtree_index + 1].bh->b_blocknr);

      root_bh = left_path->p_node[subtree_index].bh;

      ret = ocfs2_journal_dirty(handle, root_bh);
      if (ret)
            mlog_errno(ret);
}

static int ocfs2_rotate_subtree_right(struct inode *inode,
                              handle_t *handle,
                              struct ocfs2_path *left_path,
                              struct ocfs2_path *right_path,
                              int subtree_index)
{
      int ret, i;
      struct buffer_head *right_leaf_bh;
      struct buffer_head *left_leaf_bh = NULL;
      struct buffer_head *root_bh;
      struct ocfs2_extent_list *right_el, *left_el;
      struct ocfs2_extent_rec move_rec;

      left_leaf_bh = path_leaf_bh(left_path);
      left_el = path_leaf_el(left_path);

      if (left_el->l_next_free_rec != left_el->l_count) {
            ocfs2_error(inode->i_sb,
                      "Inode %llu has non-full interior leaf node %llu"
                      "(next free = %u)",
                      (unsigned long long)OCFS2_I(inode)->ip_blkno,
                      (unsigned long long)left_leaf_bh->b_blocknr,
                      le16_to_cpu(left_el->l_next_free_rec));
            return -EROFS;
      }

      /*
       * This extent block may already have an empty record, so we
       * return early if so.
       */
      if (ocfs2_is_empty_extent(&left_el->l_recs[0]))
            return 0;

      root_bh = left_path->p_node[subtree_index].bh;
      BUG_ON(root_bh != right_path->p_node[subtree_index].bh);

      ret = ocfs2_path_bh_journal_access(handle, inode, right_path,
                                 subtree_index);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      for(i = subtree_index + 1; i < path_num_items(right_path); i++) {
            ret = ocfs2_path_bh_journal_access(handle, inode,
                                       right_path, i);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            ret = ocfs2_path_bh_journal_access(handle, inode,
                                       left_path, i);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }
      }

      right_leaf_bh = path_leaf_bh(right_path);
      right_el = path_leaf_el(right_path);

      /* This is a code error, not a disk corruption. */
      mlog_bug_on_msg(!right_el->l_next_free_rec, "Inode %llu: Rotate fails "
                  "because rightmost leaf block %llu is empty\n",
                  (unsigned long long)OCFS2_I(inode)->ip_blkno,
                  (unsigned long long)right_leaf_bh->b_blocknr);

      ocfs2_create_empty_extent(right_el);

      ret = ocfs2_journal_dirty(handle, right_leaf_bh);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      /* Do the copy now. */
      i = le16_to_cpu(left_el->l_next_free_rec) - 1;
      move_rec = left_el->l_recs[i];
      right_el->l_recs[0] = move_rec;

      /*
       * Clear out the record we just copied and shift everything
       * over, leaving an empty extent in the left leaf.
       *
       * We temporarily subtract from next_free_rec so that the
       * shift will lose the tail record (which is now defunct).
       */
      le16_add_cpu(&left_el->l_next_free_rec, -1);
      ocfs2_shift_records_right(left_el);
      memset(&left_el->l_recs[0], 0, sizeof(struct ocfs2_extent_rec));
      le16_add_cpu(&left_el->l_next_free_rec, 1);

      ret = ocfs2_journal_dirty(handle, left_leaf_bh);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      ocfs2_complete_edge_insert(inode, handle, left_path, right_path,
                        subtree_index);

out:
      return ret;
}

/*
 * Given a full path, determine what cpos value would return us a path
 * containing the leaf immediately to the left of the current one.
 *
 * Will return zero if the path passed in is already the leftmost path.
 */
static int ocfs2_find_cpos_for_left_leaf(struct super_block *sb,
                               struct ocfs2_path *path, u32 *cpos)
{
      int i, j, ret = 0;
      u64 blkno;
      struct ocfs2_extent_list *el;

      BUG_ON(path->p_tree_depth == 0);

      *cpos = 0;

      blkno = path_leaf_bh(path)->b_blocknr;

      /* Start at the tree node just above the leaf and work our way up. */
      i = path->p_tree_depth - 1;
      while (i >= 0) {
            el = path->p_node[i].el;

            /*
             * Find the extent record just before the one in our
             * path.
             */
            for(j = 0; j < le16_to_cpu(el->l_next_free_rec); j++) {
                  if (le64_to_cpu(el->l_recs[j].e_blkno) == blkno) {
                        if (j == 0) {
                              if (i == 0) {
                                    /*
                                     * We've determined that the
                                     * path specified is already
                                     * the leftmost one - return a
                                     * cpos of zero.
                                     */
                                    goto out;
                              }
                              /*
                               * The leftmost record points to our
                               * leaf - we need to travel up the
                               * tree one level.
                               */
                              goto next_node;
                        }

                        *cpos = le32_to_cpu(el->l_recs[j - 1].e_cpos);
                        *cpos = *cpos + ocfs2_rec_clusters(el,
                                             &el->l_recs[j - 1]);
                        *cpos = *cpos - 1;
                        goto out;
                  }
            }

            /*
             * If we got here, we never found a valid node where
             * the tree indicated one should be.
             */
            ocfs2_error(sb,
                      "Invalid extent tree at extent block %llu\n",
                      (unsigned long long)blkno);
            ret = -EROFS;
            goto out;

next_node:
            blkno = path->p_node[i].bh->b_blocknr;
            i--;
      }

out:
      return ret;
}

/*
 * Extend the transaction by enough credits to complete the rotation,
 * and still leave at least the original number of credits allocated
 * to this transaction.
 */
static int ocfs2_extend_rotate_transaction(handle_t *handle, int subtree_depth,
                                 int op_credits,
                                 struct ocfs2_path *path)
{
      int credits = (path->p_tree_depth - subtree_depth) * 2 + 1 + op_credits;

      if (handle->h_buffer_credits < credits)
            return ocfs2_extend_trans(handle, credits);

      return 0;
}

/*
 * Trap the case where we're inserting into the theoretical range past
 * the _actual_ left leaf range. Otherwise, we'll rotate a record
 * whose cpos is less than ours into the right leaf.
 *
 * It's only necessary to look at the rightmost record of the left
 * leaf because the logic that calls us should ensure that the
 * theoretical ranges in the path components above the leaves are
 * correct.
 */
static int ocfs2_rotate_requires_path_adjustment(struct ocfs2_path *left_path,
                                     u32 insert_cpos)
{
      struct ocfs2_extent_list *left_el;
      struct ocfs2_extent_rec *rec;
      int next_free;

      left_el = path_leaf_el(left_path);
      next_free = le16_to_cpu(left_el->l_next_free_rec);
      rec = &left_el->l_recs[next_free - 1];

      if (insert_cpos > le32_to_cpu(rec->e_cpos))
            return 1;
      return 0;
}

static int ocfs2_leftmost_rec_contains(struct ocfs2_extent_list *el, u32 cpos)
{
      int next_free = le16_to_cpu(el->l_next_free_rec);
      unsigned int range;
      struct ocfs2_extent_rec *rec;

      if (next_free == 0)
            return 0;

      rec = &el->l_recs[0];
      if (ocfs2_is_empty_extent(rec)) {
            /* Empty list. */
            if (next_free == 1)
                  return 0;
            rec = &el->l_recs[1];
      }

      range = le32_to_cpu(rec->e_cpos) + ocfs2_rec_clusters(el, rec);
      if (cpos >= le32_to_cpu(rec->e_cpos) && cpos < range)
            return 1;
      return 0;
}

/*
 * Rotate all the records in a btree right one record, starting at insert_cpos.
 *
 * The path to the rightmost leaf should be passed in.
 *
 * The array is assumed to be large enough to hold an entire path (tree depth).
 *
 * Upon succesful return from this function:
 *
 * - The 'right_path' array will contain a path to the leaf block
 *   whose range contains e_cpos.
 * - That leaf block will have a single empty extent in list index 0.
 * - In the case that the rotation requires a post-insert update,
 *   *ret_left_path will contain a valid path which can be passed to
 *   ocfs2_insert_path().
 */
static int ocfs2_rotate_tree_right(struct inode *inode,
                           handle_t *handle,
                           enum ocfs2_split_type split,
                           u32 insert_cpos,
                           struct ocfs2_path *right_path,
                           struct ocfs2_path **ret_left_path)
{
      int ret, start, orig_credits = handle->h_buffer_credits;
      u32 cpos;
      struct ocfs2_path *left_path = NULL;

      *ret_left_path = NULL;

      left_path = ocfs2_new_path_from_path(right_path);
      if (!left_path) {
            ret = -ENOMEM;
            mlog_errno(ret);
            goto out;
      }

      ret = ocfs2_find_cpos_for_left_leaf(inode->i_sb, right_path, &cpos);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      mlog(0, "Insert: %u, first left path cpos: %u\n", insert_cpos, cpos);

      /*
       * What we want to do here is:
       *
       * 1) Start with the rightmost path.
       *
       * 2) Determine a path to the leaf block directly to the left
       *    of that leaf.
       *
       * 3) Determine the 'subtree root' - the lowest level tree node
       *    which contains a path to both leaves.
       *
       * 4) Rotate the subtree.
       *
       * 5) Find the next subtree by considering the left path to be
       *    the new right path.
       *
       * The check at the top of this while loop also accepts
       * insert_cpos == cpos because cpos is only a _theoretical_
       * value to get us the left path - insert_cpos might very well
       * be filling that hole.
       *
       * Stop at a cpos of '0' because we either started at the
       * leftmost branch (i.e., a tree with one branch and a
       * rotation inside of it), or we've gone as far as we can in
       * rotating subtrees.
       */
      while (cpos && insert_cpos <= cpos) {
            mlog(0, "Rotating a tree: ins. cpos: %u, left path cpos: %u\n",
                 insert_cpos, cpos);

            ret = ocfs2_find_path(inode, left_path, cpos);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            mlog_bug_on_msg(path_leaf_bh(left_path) ==
                        path_leaf_bh(right_path),
                        "Inode %lu: error during insert of %u "
                        "(left path cpos %u) results in two identical "
                        "paths ending at %llu\n",
                        inode->i_ino, insert_cpos, cpos,
                        (unsigned long long)
                        path_leaf_bh(left_path)->b_blocknr);

            if (split == SPLIT_NONE &&
                ocfs2_rotate_requires_path_adjustment(left_path,
                                            insert_cpos)) {

                  /*
                   * We've rotated the tree as much as we
                   * should. The rest is up to
                   * ocfs2_insert_path() to complete, after the
                   * record insertion. We indicate this
                   * situation by returning the left path.
                   *
                   * The reason we don't adjust the records here
                   * before the record insert is that an error
                   * later might break the rule where a parent
                   * record e_cpos will reflect the actual
                   * e_cpos of the 1st nonempty record of the
                   * child list.
                   */
                  *ret_left_path = left_path;
                  goto out_ret_path;
            }

            start = ocfs2_find_subtree_root(inode, left_path, right_path);

            mlog(0, "Subtree root at index %d (blk %llu, depth %d)\n",
                 start,
                 (unsigned long long) right_path->p_node[start].bh->b_blocknr,
                 right_path->p_tree_depth);

            ret = ocfs2_extend_rotate_transaction(handle, start,
                                          orig_credits, right_path);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            ret = ocfs2_rotate_subtree_right(inode, handle, left_path,
                                     right_path, start);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            if (split != SPLIT_NONE &&
                ocfs2_leftmost_rec_contains(path_leaf_el(right_path),
                                    insert_cpos)) {
                  /*
                   * A rotate moves the rightmost left leaf
                   * record over to the leftmost right leaf
                   * slot. If we're doing an extent split
                   * instead of a real insert, then we have to
                   * check that the extent to be split wasn't
                   * just moved over. If it was, then we can
                   * exit here, passing left_path back -
                   * ocfs2_split_extent() is smart enough to
                   * search both leaves.
                   */
                  *ret_left_path = left_path;
                  goto out_ret_path;
            }

            /*
             * There is no need to re-read the next right path
             * as we know that it'll be our current left
             * path. Optimize by copying values instead.
             */
            ocfs2_mv_path(right_path, left_path);

            ret = ocfs2_find_cpos_for_left_leaf(inode->i_sb, right_path,
                                        &cpos);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }
      }

out:
      ocfs2_free_path(left_path);

out_ret_path:
      return ret;
}

static int ocfs2_update_edge_lengths(struct inode *inode, handle_t *handle,
                             int subtree_index, struct ocfs2_path *path)
{
      int i, idx, ret;
      struct ocfs2_extent_rec *rec;
      struct ocfs2_extent_list *el;
      struct ocfs2_extent_block *eb;
      u32 range;

      /*
       * In normal tree rotation process, we will never touch the
       * tree branch above subtree_index and ocfs2_extend_rotate_transaction
       * doesn't reserve the credits for them either.
       *
       * But we do have a special case here which will update the rightmost
       * records for all the bh in the path.
       * So we have to allocate extra credits and access them.
       */
      ret = ocfs2_extend_trans(handle,
                         handle->h_buffer_credits + subtree_index);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      ret = ocfs2_journal_access_path(inode, handle, path);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      /* Path should always be rightmost. */
      eb = (struct ocfs2_extent_block *)path_leaf_bh(path)->b_data;
      BUG_ON(eb->h_next_leaf_blk != 0ULL);

      el = &eb->h_list;
      BUG_ON(le16_to_cpu(el->l_next_free_rec) == 0);
      idx = le16_to_cpu(el->l_next_free_rec) - 1;
      rec = &el->l_recs[idx];
      range = le32_to_cpu(rec->e_cpos) + ocfs2_rec_clusters(el, rec);

      for (i = 0; i < path->p_tree_depth; i++) {
            el = path->p_node[i].el;
            idx = le16_to_cpu(el->l_next_free_rec) - 1;
            rec = &el->l_recs[idx];

            rec->e_int_clusters = cpu_to_le32(range);
            le32_add_cpu(&rec->e_int_clusters, -le32_to_cpu(rec->e_cpos));

            ocfs2_journal_dirty(handle, path->p_node[i].bh);
      }
out:
      return ret;
}

static void ocfs2_unlink_path(struct inode *inode, handle_t *handle,
                        struct ocfs2_cached_dealloc_ctxt *dealloc,
                        struct ocfs2_path *path, int unlink_start)
{
      int ret, i;
      struct ocfs2_extent_block *eb;
      struct ocfs2_extent_list *el;
      struct buffer_head *bh;

      for(i = unlink_start; i < path_num_items(path); i++) {
            bh = path->p_node[i].bh;

            eb = (struct ocfs2_extent_block *)bh->b_data;
            /*
             * Not all nodes might have had their final count
             * decremented by the caller - handle this here.
             */
            el = &eb->h_list;
            if (le16_to_cpu(el->l_next_free_rec) > 1) {
                  mlog(ML_ERROR,
                       "Inode %llu, attempted to remove extent block "
                       "%llu with %u records\n",
                       (unsigned long long)OCFS2_I(inode)->ip_blkno,
                       (unsigned long long)le64_to_cpu(eb->h_blkno),
                       le16_to_cpu(el->l_next_free_rec));

                  ocfs2_journal_dirty(handle, bh);
                  ocfs2_remove_from_cache(inode, bh);
                  continue;
            }

            el->l_next_free_rec = 0;
            memset(&el->l_recs[0], 0, sizeof(struct ocfs2_extent_rec));

            ocfs2_journal_dirty(handle, bh);

            ret = ocfs2_cache_extent_block_free(dealloc, eb);
            if (ret)
                  mlog_errno(ret);

            ocfs2_remove_from_cache(inode, bh);
      }
}

static void ocfs2_unlink_subtree(struct inode *inode, handle_t *handle,
                         struct ocfs2_path *left_path,
                         struct ocfs2_path *right_path,
                         int subtree_index,
                         struct ocfs2_cached_dealloc_ctxt *dealloc)
{
      int i;
      struct buffer_head *root_bh = left_path->p_node[subtree_index].bh;
      struct ocfs2_extent_list *root_el = left_path->p_node[subtree_index].el;
      struct ocfs2_extent_list *el;
      struct ocfs2_extent_block *eb;

      el = path_leaf_el(left_path);

      eb = (struct ocfs2_extent_block *)right_path->p_node[subtree_index + 1].bh->b_data;

      for(i = 1; i < le16_to_cpu(root_el->l_next_free_rec); i++)
            if (root_el->l_recs[i].e_blkno == eb->h_blkno)
                  break;

      BUG_ON(i >= le16_to_cpu(root_el->l_next_free_rec));

      memset(&root_el->l_recs[i], 0, sizeof(struct ocfs2_extent_rec));
      le16_add_cpu(&root_el->l_next_free_rec, -1);

      eb = (struct ocfs2_extent_block *)path_leaf_bh(left_path)->b_data;
      eb->h_next_leaf_blk = 0;

      ocfs2_journal_dirty(handle, root_bh);
      ocfs2_journal_dirty(handle, path_leaf_bh(left_path));

      ocfs2_unlink_path(inode, handle, dealloc, right_path,
                    subtree_index + 1);
}

static int ocfs2_rotate_subtree_left(struct inode *inode, handle_t *handle,
                             struct ocfs2_path *left_path,
                             struct ocfs2_path *right_path,
                             int subtree_index,
                             struct ocfs2_cached_dealloc_ctxt *dealloc,
                             int *deleted,
                             struct ocfs2_extent_tree *et)
{
      int ret, i, del_right_subtree = 0, right_has_empty = 0;
      struct buffer_head *root_bh, *et_root_bh = path_root_bh(right_path);
      struct ocfs2_extent_list *right_leaf_el, *left_leaf_el;
      struct ocfs2_extent_block *eb;

      *deleted = 0;

      right_leaf_el = path_leaf_el(right_path);
      left_leaf_el = path_leaf_el(left_path);
      root_bh = left_path->p_node[subtree_index].bh;
      BUG_ON(root_bh != right_path->p_node[subtree_index].bh);

      if (!ocfs2_is_empty_extent(&left_leaf_el->l_recs[0]))
            return 0;

      eb = (struct ocfs2_extent_block *)path_leaf_bh(right_path)->b_data;
      if (ocfs2_is_empty_extent(&right_leaf_el->l_recs[0])) {
            /*
             * It's legal for us to proceed if the right leaf is
             * the rightmost one and it has an empty extent. There
             * are two cases to handle - whether the leaf will be
             * empty after removal or not. If the leaf isn't empty
             * then just remove the empty extent up front. The
             * next block will handle empty leaves by flagging
             * them for unlink.
             *
             * Non rightmost leaves will throw -EAGAIN and the
             * caller can manually move the subtree and retry.
             */

            if (eb->h_next_leaf_blk != 0ULL)
                  return -EAGAIN;

            if (le16_to_cpu(right_leaf_el->l_next_free_rec) > 1) {
                  ret = ocfs2_journal_access_eb(handle, inode,
                                          path_leaf_bh(right_path),
                                          OCFS2_JOURNAL_ACCESS_WRITE);
                  if (ret) {
                        mlog_errno(ret);
                        goto out;
                  }

                  ocfs2_remove_empty_extent(right_leaf_el);
            } else
                  right_has_empty = 1;
      }

      if (eb->h_next_leaf_blk == 0ULL &&
          le16_to_cpu(right_leaf_el->l_next_free_rec) == 1) {
            /*
             * We have to update i_last_eb_blk during the meta
             * data delete.
             */
            ret = ocfs2_et_root_journal_access(handle, inode, et,
                                       OCFS2_JOURNAL_ACCESS_WRITE);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            del_right_subtree = 1;
      }

      /*
       * Getting here with an empty extent in the right path implies
       * that it's the rightmost path and will be deleted.
       */
      BUG_ON(right_has_empty && !del_right_subtree);

      ret = ocfs2_path_bh_journal_access(handle, inode, right_path,
                                 subtree_index);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      for(i = subtree_index + 1; i < path_num_items(right_path); i++) {
            ret = ocfs2_path_bh_journal_access(handle, inode,
                                       right_path, i);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            ret = ocfs2_path_bh_journal_access(handle, inode,
                                       left_path, i);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }
      }

      if (!right_has_empty) {
            /*
             * Only do this if we're moving a real
             * record. Otherwise, the action is delayed until
             * after removal of the right path in which case we
             * can do a simple shift to remove the empty extent.
             */
            ocfs2_rotate_leaf(left_leaf_el, &right_leaf_el->l_recs[0]);
            memset(&right_leaf_el->l_recs[0], 0,
                   sizeof(struct ocfs2_extent_rec));
      }
      if (eb->h_next_leaf_blk == 0ULL) {
            /*
             * Move recs over to get rid of empty extent, decrease
             * next_free. This is allowed to remove the last
             * extent in our leaf (setting l_next_free_rec to
             * zero) - the delete code below won't care.
             */
            ocfs2_remove_empty_extent(right_leaf_el);
      }

      ret = ocfs2_journal_dirty(handle, path_leaf_bh(left_path));
      if (ret)
            mlog_errno(ret);
      ret = ocfs2_journal_dirty(handle, path_leaf_bh(right_path));
      if (ret)
            mlog_errno(ret);

      if (del_right_subtree) {
            ocfs2_unlink_subtree(inode, handle, left_path, right_path,
                             subtree_index, dealloc);
            ret = ocfs2_update_edge_lengths(inode, handle, subtree_index,
                                    left_path);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            eb = (struct ocfs2_extent_block *)path_leaf_bh(left_path)->b_data;
            ocfs2_et_set_last_eb_blk(et, le64_to_cpu(eb->h_blkno));

            /*
             * Removal of the extent in the left leaf was skipped
             * above so we could delete the right path
             * 1st.
             */
            if (right_has_empty)
                  ocfs2_remove_empty_extent(left_leaf_el);

            ret = ocfs2_journal_dirty(handle, et_root_bh);
            if (ret)
                  mlog_errno(ret);

            *deleted = 1;
      } else
            ocfs2_complete_edge_insert(inode, handle, left_path, right_path,
                                 subtree_index);

out:
      return ret;
}

/*
 * Given a full path, determine what cpos value would return us a path
 * containing the leaf immediately to the right of the current one.
 *
 * Will return zero if the path passed in is already the rightmost path.
 *
 * This looks similar, but is subtly different to
 * ocfs2_find_cpos_for_left_leaf().
 */
static int ocfs2_find_cpos_for_right_leaf(struct super_block *sb,
                                struct ocfs2_path *path, u32 *cpos)
{
      int i, j, ret = 0;
      u64 blkno;
      struct ocfs2_extent_list *el;

      *cpos = 0;

      if (path->p_tree_depth == 0)
            return 0;

      blkno = path_leaf_bh(path)->b_blocknr;

      /* Start at the tree node just above the leaf and work our way up. */
      i = path->p_tree_depth - 1;
      while (i >= 0) {
            int next_free;

            el = path->p_node[i].el;

            /*
             * Find the extent record just after the one in our
             * path.
             */
            next_free = le16_to_cpu(el->l_next_free_rec);
            for(j = 0; j < le16_to_cpu(el->l_next_free_rec); j++) {
                  if (le64_to_cpu(el->l_recs[j].e_blkno) == blkno) {
                        if (j == (next_free - 1)) {
                              if (i == 0) {
                                    /*
                                     * We've determined that the
                                     * path specified is already
                                     * the rightmost one - return a
                                     * cpos of zero.
                                     */
                                    goto out;
                              }
                              /*
                               * The rightmost record points to our
                               * leaf - we need to travel up the
                               * tree one level.
                               */
                              goto next_node;
                        }

                        *cpos = le32_to_cpu(el->l_recs[j + 1].e_cpos);
                        goto out;
                  }
            }

            /*
             * If we got here, we never found a valid node where
             * the tree indicated one should be.
             */
            ocfs2_error(sb,
                      "Invalid extent tree at extent block %llu\n",
                      (unsigned long long)blkno);
            ret = -EROFS;
            goto out;

next_node:
            blkno = path->p_node[i].bh->b_blocknr;
            i--;
      }

out:
      return ret;
}

static int ocfs2_rotate_rightmost_leaf_left(struct inode *inode,
                                  handle_t *handle,
                                  struct ocfs2_path *path)
{
      int ret;
      struct buffer_head *bh = path_leaf_bh(path);
      struct ocfs2_extent_list *el = path_leaf_el(path);

      if (!ocfs2_is_empty_extent(&el->l_recs[0]))
            return 0;

      ret = ocfs2_path_bh_journal_access(handle, inode, path,
                                 path_num_items(path) - 1);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      ocfs2_remove_empty_extent(el);

      ret = ocfs2_journal_dirty(handle, bh);
      if (ret)
            mlog_errno(ret);

out:
      return ret;
}

static int __ocfs2_rotate_tree_left(struct inode *inode,
                            handle_t *handle, int orig_credits,
                            struct ocfs2_path *path,
                            struct ocfs2_cached_dealloc_ctxt *dealloc,
                            struct ocfs2_path **empty_extent_path,
                            struct ocfs2_extent_tree *et)
{
      int ret, subtree_root, deleted;
      u32 right_cpos;
      struct ocfs2_path *left_path = NULL;
      struct ocfs2_path *right_path = NULL;

      BUG_ON(!ocfs2_is_empty_extent(&(path_leaf_el(path)->l_recs[0])));

      *empty_extent_path = NULL;

      ret = ocfs2_find_cpos_for_right_leaf(inode->i_sb, path,
                                   &right_cpos);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      left_path = ocfs2_new_path_from_path(path);
      if (!left_path) {
            ret = -ENOMEM;
            mlog_errno(ret);
            goto out;
      }

      ocfs2_cp_path(left_path, path);

      right_path = ocfs2_new_path_from_path(path);
      if (!right_path) {
            ret = -ENOMEM;
            mlog_errno(ret);
            goto out;
      }

      while (right_cpos) {
            ret = ocfs2_find_path(inode, right_path, right_cpos);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            subtree_root = ocfs2_find_subtree_root(inode, left_path,
                                           right_path);

            mlog(0, "Subtree root at index %d (blk %llu, depth %d)\n",
                 subtree_root,
                 (unsigned long long)
                 right_path->p_node[subtree_root].bh->b_blocknr,
                 right_path->p_tree_depth);

            ret = ocfs2_extend_rotate_transaction(handle, subtree_root,
                                          orig_credits, left_path);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            /*
             * Caller might still want to make changes to the
             * tree root, so re-add it to the journal here.
             */
            ret = ocfs2_path_bh_journal_access(handle, inode,
                                       left_path, 0);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            ret = ocfs2_rotate_subtree_left(inode, handle, left_path,
                                    right_path, subtree_root,
                                    dealloc, &deleted, et);
            if (ret == -EAGAIN) {
                  /*
                   * The rotation has to temporarily stop due to
                   * the right subtree having an empty
                   * extent. Pass it back to the caller for a
                   * fixup.
                   */
                  *empty_extent_path = right_path;
                  right_path = NULL;
                  goto out;
            }
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            /*
             * The subtree rotate might have removed records on
             * the rightmost edge. If so, then rotation is
             * complete.
             */
            if (deleted)
                  break;

            ocfs2_mv_path(left_path, right_path);

            ret = ocfs2_find_cpos_for_right_leaf(inode->i_sb, left_path,
                                         &right_cpos);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }
      }

out:
      ocfs2_free_path(right_path);
      ocfs2_free_path(left_path);

      return ret;
}

static int ocfs2_remove_rightmost_path(struct inode *inode, handle_t *handle,
                        struct ocfs2_path *path,
                        struct ocfs2_cached_dealloc_ctxt *dealloc,
                        struct ocfs2_extent_tree *et)
{
      int ret, subtree_index;
      u32 cpos;
      struct ocfs2_path *left_path = NULL;
      struct ocfs2_extent_block *eb;
      struct ocfs2_extent_list *el;


      ret = ocfs2_et_sanity_check(inode, et);
      if (ret)
            goto out;
      /*
       * There's two ways we handle this depending on
       * whether path is the only existing one.
       */
      ret = ocfs2_extend_rotate_transaction(handle, 0,
                                    handle->h_buffer_credits,
                                    path);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      ret = ocfs2_journal_access_path(inode, handle, path);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      ret = ocfs2_find_cpos_for_left_leaf(inode->i_sb, path, &cpos);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      if (cpos) {
            /*
             * We have a path to the left of this one - it needs
             * an update too.
             */
            left_path = ocfs2_new_path_from_path(path);
            if (!left_path) {
                  ret = -ENOMEM;
                  mlog_errno(ret);
                  goto out;
            }

            ret = ocfs2_find_path(inode, left_path, cpos);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            ret = ocfs2_journal_access_path(inode, handle, left_path);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            subtree_index = ocfs2_find_subtree_root(inode, left_path, path);

            ocfs2_unlink_subtree(inode, handle, left_path, path,
                             subtree_index, dealloc);
            ret = ocfs2_update_edge_lengths(inode, handle, subtree_index,
                                    left_path);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            eb = (struct ocfs2_extent_block *)path_leaf_bh(left_path)->b_data;
            ocfs2_et_set_last_eb_blk(et, le64_to_cpu(eb->h_blkno));
      } else {
            /*
             * 'path' is also the leftmost path which
             * means it must be the only one. This gets
             * handled differently because we want to
             * revert the inode back to having extents
             * in-line.
             */
            ocfs2_unlink_path(inode, handle, dealloc, path, 1);

            el = et->et_root_el;
            el->l_tree_depth = 0;
            el->l_next_free_rec = 0;
            memset(&el->l_recs[0], 0, sizeof(struct ocfs2_extent_rec));

            ocfs2_et_set_last_eb_blk(et, 0);
      }

      ocfs2_journal_dirty(handle, path_root_bh(path));

out:
      ocfs2_free_path(left_path);
      return ret;
}

/*
 * Left rotation of btree records.
 *
 * In many ways, this is (unsurprisingly) the opposite of right
 * rotation. We start at some non-rightmost path containing an empty
 * extent in the leaf block. The code works its way to the rightmost
 * path by rotating records to the left in every subtree.
 *
 * This is used by any code which reduces the number of extent records
 * in a leaf. After removal, an empty record should be placed in the
 * leftmost list position.
 *
 * This won't handle a length update of the rightmost path records if
 * the rightmost tree leaf record is removed so the caller is
 * responsible for detecting and correcting that.
 */
static int ocfs2_rotate_tree_left(struct inode *inode, handle_t *handle,
                          struct ocfs2_path *path,
                          struct ocfs2_cached_dealloc_ctxt *dealloc,
                          struct ocfs2_extent_tree *et)
{
      int ret, orig_credits = handle->h_buffer_credits;
      struct ocfs2_path *tmp_path = NULL, *restart_path = NULL;
      struct ocfs2_extent_block *eb;
      struct ocfs2_extent_list *el;

      el = path_leaf_el(path);
      if (!ocfs2_is_empty_extent(&el->l_recs[0]))
            return 0;

      if (path->p_tree_depth == 0) {
rightmost_no_delete:
            /*
             * Inline extents. This is trivially handled, so do
             * it up front.
             */
            ret = ocfs2_rotate_rightmost_leaf_left(inode, handle,
                                           path);
            if (ret)
                  mlog_errno(ret);
            goto out;
      }

      /*
       * Handle rightmost branch now. There's several cases:
       *  1) simple rotation leaving records in there. That's trivial.
       *  2) rotation requiring a branch delete - there's no more
       *     records left. Two cases of this:
       *     a) There are branches to the left.
       *     b) This is also the leftmost (the only) branch.
       *
       *  1) is handled via ocfs2_rotate_rightmost_leaf_left()
       *  2a) we need the left branch so that we can update it with the unlink
       *  2b) we need to bring the inode back to inline extents.
       */

      eb = (struct ocfs2_extent_block *)path_leaf_bh(path)->b_data;
      el = &eb->h_list;
      if (eb->h_next_leaf_blk == 0) {
            /*
             * This gets a bit tricky if we're going to delete the
             * rightmost path. Get the other cases out of the way
             * 1st.
             */
            if (le16_to_cpu(el->l_next_free_rec) > 1)
                  goto rightmost_no_delete;

            if (le16_to_cpu(el->l_next_free_rec) == 0) {
                  ret = -EIO;
                  ocfs2_error(inode->i_sb,
                            "Inode %llu has empty extent block at %llu",
                            (unsigned long long)OCFS2_I(inode)->ip_blkno,
                            (unsigned long long)le64_to_cpu(eb->h_blkno));
                  goto out;
            }

            /*
             * XXX: The caller can not trust "path" any more after
             * this as it will have been deleted. What do we do?
             *
             * In theory the rotate-for-merge code will never get
             * here because it'll always ask for a rotate in a
             * nonempty list.
             */

            ret = ocfs2_remove_rightmost_path(inode, handle, path,
                                      dealloc, et);
            if (ret)
                  mlog_errno(ret);
            goto out;
      }

      /*
       * Now we can loop, remembering the path we get from -EAGAIN
       * and restarting from there.
       */
try_rotate:
      ret = __ocfs2_rotate_tree_left(inode, handle, orig_credits, path,
                               dealloc, &restart_path, et);
      if (ret && ret != -EAGAIN) {
            mlog_errno(ret);
            goto out;
      }

      while (ret == -EAGAIN) {
            tmp_path = restart_path;
            restart_path = NULL;

            ret = __ocfs2_rotate_tree_left(inode, handle, orig_credits,
                                     tmp_path, dealloc,
                                     &restart_path, et);
            if (ret && ret != -EAGAIN) {
                  mlog_errno(ret);
                  goto out;
            }

            ocfs2_free_path(tmp_path);
            tmp_path = NULL;

            if (ret == 0)
                  goto try_rotate;
      }

out:
      ocfs2_free_path(tmp_path);
      ocfs2_free_path(restart_path);
      return ret;
}

static void ocfs2_cleanup_merge(struct ocfs2_extent_list *el,
                        int index)
{
      struct ocfs2_extent_rec *rec = &el->l_recs[index];
      unsigned int size;

      if (rec->e_leaf_clusters == 0) {
            /*
             * We consumed all of the merged-from record. An empty
             * extent cannot exist anywhere but the 1st array
             * position, so move things over if the merged-from
             * record doesn't occupy that position.
             *
             * This creates a new empty extent so the caller
             * should be smart enough to have removed any existing
             * ones.
             */
            if (index > 0) {
                  BUG_ON(ocfs2_is_empty_extent(&el->l_recs[0]));
                  size = index * sizeof(struct ocfs2_extent_rec);
                  memmove(&el->l_recs[1], &el->l_recs[0], size);
            }

            /*
             * Always memset - the caller doesn't check whether it
             * created an empty extent, so there could be junk in
             * the other fields.
             */
            memset(&el->l_recs[0], 0, sizeof(struct ocfs2_extent_rec));
      }
}

static int ocfs2_get_right_path(struct inode *inode,
                        struct ocfs2_path *left_path,
                        struct ocfs2_path **ret_right_path)
{
      int ret;
      u32 right_cpos;
      struct ocfs2_path *right_path = NULL;
      struct ocfs2_extent_list *left_el;

      *ret_right_path = NULL;

      /* This function shouldn't be called for non-trees. */
      BUG_ON(left_path->p_tree_depth == 0);

      left_el = path_leaf_el(left_path);
      BUG_ON(left_el->l_next_free_rec != left_el->l_count);

      ret = ocfs2_find_cpos_for_right_leaf(inode->i_sb, left_path,
                                   &right_cpos);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      /* This function shouldn't be called for the rightmost leaf. */
      BUG_ON(right_cpos == 0);

      right_path = ocfs2_new_path_from_path(left_path);
      if (!right_path) {
            ret = -ENOMEM;
            mlog_errno(ret);
            goto out;
      }

      ret = ocfs2_find_path(inode, right_path, right_cpos);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      *ret_right_path = right_path;
out:
      if (ret)
            ocfs2_free_path(right_path);
      return ret;
}

/*
 * Remove split_rec clusters from the record at index and merge them
 * onto the beginning of the record "next" to it.
 * For index < l_count - 1, the next means the extent rec at index + 1.
 * For index == l_count - 1, the "next" means the 1st extent rec of the
 * next extent block.
 */
static int ocfs2_merge_rec_right(struct inode *inode,
                         struct ocfs2_path *left_path,
                         handle_t *handle,
                         struct ocfs2_extent_rec *split_rec,
                         int index)
{
      int ret, next_free, i;
      unsigned int split_clusters = le16_to_cpu(split_rec->e_leaf_clusters);
      struct ocfs2_extent_rec *left_rec;
      struct ocfs2_extent_rec *right_rec;
      struct ocfs2_extent_list *right_el;
      struct ocfs2_path *right_path = NULL;
      int subtree_index = 0;
      struct ocfs2_extent_list *el = path_leaf_el(left_path);
      struct buffer_head *bh = path_leaf_bh(left_path);
      struct buffer_head *root_bh = NULL;

      BUG_ON(index >= le16_to_cpu(el->l_next_free_rec));
      left_rec = &el->l_recs[index];

      if (index == le16_to_cpu(el->l_next_free_rec) - 1 &&
          le16_to_cpu(el->l_next_free_rec) == le16_to_cpu(el->l_count)) {
            /* we meet with a cross extent block merge. */
            ret = ocfs2_get_right_path(inode, left_path, &right_path);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            right_el = path_leaf_el(right_path);
            next_free = le16_to_cpu(right_el->l_next_free_rec);
            BUG_ON(next_free <= 0);
            right_rec = &right_el->l_recs[0];
            if (ocfs2_is_empty_extent(right_rec)) {
                  BUG_ON(next_free <= 1);
                  right_rec = &right_el->l_recs[1];
            }

            BUG_ON(le32_to_cpu(left_rec->e_cpos) +
                   le16_to_cpu(left_rec->e_leaf_clusters) !=
                   le32_to_cpu(right_rec->e_cpos));

            subtree_index = ocfs2_find_subtree_root(inode,
                                          left_path, right_path);

            ret = ocfs2_extend_rotate_transaction(handle, subtree_index,
                                          handle->h_buffer_credits,
                                          right_path);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            root_bh = left_path->p_node[subtree_index].bh;
            BUG_ON(root_bh != right_path->p_node[subtree_index].bh);

            ret = ocfs2_path_bh_journal_access(handle, inode, right_path,
                                       subtree_index);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            for (i = subtree_index + 1;
                 i < path_num_items(right_path); i++) {
                  ret = ocfs2_path_bh_journal_access(handle, inode,
                                             right_path, i);
                  if (ret) {
                        mlog_errno(ret);
                        goto out;
                  }

                  ret = ocfs2_path_bh_journal_access(handle, inode,
                                             left_path, i);
                  if (ret) {
                        mlog_errno(ret);
                        goto out;
                  }
            }

      } else {
            BUG_ON(index == le16_to_cpu(el->l_next_free_rec) - 1);
            right_rec = &el->l_recs[index + 1];
      }

      ret = ocfs2_path_bh_journal_access(handle, inode, left_path,
                                 path_num_items(left_path) - 1);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      le16_add_cpu(&left_rec->e_leaf_clusters, -split_clusters);

      le32_add_cpu(&right_rec->e_cpos, -split_clusters);
      le64_add_cpu(&right_rec->e_blkno,
                 -ocfs2_clusters_to_blocks(inode->i_sb, split_clusters));
      le16_add_cpu(&right_rec->e_leaf_clusters, split_clusters);

      ocfs2_cleanup_merge(el, index);

      ret = ocfs2_journal_dirty(handle, bh);
      if (ret)
            mlog_errno(ret);

      if (right_path) {
            ret = ocfs2_journal_dirty(handle, path_leaf_bh(right_path));
            if (ret)
                  mlog_errno(ret);

            ocfs2_complete_edge_insert(inode, handle, left_path,
                                 right_path, subtree_index);
      }
out:
      if (right_path)
            ocfs2_free_path(right_path);
      return ret;
}

static int ocfs2_get_left_path(struct inode *inode,
                         struct ocfs2_path *right_path,
                         struct ocfs2_path **ret_left_path)
{
      int ret;
      u32 left_cpos;
      struct ocfs2_path *left_path = NULL;

      *ret_left_path = NULL;

      /* This function shouldn't be called for non-trees. */
      BUG_ON(right_path->p_tree_depth == 0);

      ret = ocfs2_find_cpos_for_left_leaf(inode->i_sb,
                                  right_path, &left_cpos);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      /* This function shouldn't be called for the leftmost leaf. */
      BUG_ON(left_cpos == 0);

      left_path = ocfs2_new_path_from_path(right_path);
      if (!left_path) {
            ret = -ENOMEM;
            mlog_errno(ret);
            goto out;
      }

      ret = ocfs2_find_path(inode, left_path, left_cpos);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      *ret_left_path = left_path;
out:
      if (ret)
            ocfs2_free_path(left_path);
      return ret;
}

/*
 * Remove split_rec clusters from the record at index and merge them
 * onto the tail of the record "before" it.
 * For index > 0, the "before" means the extent rec at index - 1.
 *
 * For index == 0, the "before" means the last record of the previous
 * extent block. And there is also a situation that we may need to
 * remove the rightmost leaf extent block in the right_path and change
 * the right path to indicate the new rightmost path.
 */
static int ocfs2_merge_rec_left(struct inode *inode,
                        struct ocfs2_path *right_path,
                        handle_t *handle,
                        struct ocfs2_extent_rec *split_rec,
                        struct ocfs2_cached_dealloc_ctxt *dealloc,
                        struct ocfs2_extent_tree *et,
                        int index)
{
      int ret, i, subtree_index = 0, has_empty_extent = 0;
      unsigned int split_clusters = le16_to_cpu(split_rec->e_leaf_clusters);
      struct ocfs2_extent_rec *left_rec;
      struct ocfs2_extent_rec *right_rec;
      struct ocfs2_extent_list *el = path_leaf_el(right_path);
      struct buffer_head *bh = path_leaf_bh(right_path);
      struct buffer_head *root_bh = NULL;
      struct ocfs2_path *left_path = NULL;
      struct ocfs2_extent_list *left_el;

      BUG_ON(index < 0);

      right_rec = &el->l_recs[index];
      if (index == 0) {
            /* we meet with a cross extent block merge. */
            ret = ocfs2_get_left_path(inode, right_path, &left_path);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            left_el = path_leaf_el(left_path);
            BUG_ON(le16_to_cpu(left_el->l_next_free_rec) !=
                   le16_to_cpu(left_el->l_count));

            left_rec = &left_el->l_recs[
                        le16_to_cpu(left_el->l_next_free_rec) - 1];
            BUG_ON(le32_to_cpu(left_rec->e_cpos) +
                   le16_to_cpu(left_rec->e_leaf_clusters) !=
                   le32_to_cpu(split_rec->e_cpos));

            subtree_index = ocfs2_find_subtree_root(inode,
                                          left_path, right_path);

            ret = ocfs2_extend_rotate_transaction(handle, subtree_index,
                                          handle->h_buffer_credits,
                                          left_path);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            root_bh = left_path->p_node[subtree_index].bh;
            BUG_ON(root_bh != right_path->p_node[subtree_index].bh);

            ret = ocfs2_path_bh_journal_access(handle, inode, right_path,
                                       subtree_index);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            for (i = subtree_index + 1;
                 i < path_num_items(right_path); i++) {
                  ret = ocfs2_path_bh_journal_access(handle, inode,
                                             right_path, i);
                  if (ret) {
                        mlog_errno(ret);
                        goto out;
                  }

                  ret = ocfs2_path_bh_journal_access(handle, inode,
                                             left_path, i);
                  if (ret) {
                        mlog_errno(ret);
                        goto out;
                  }
            }
      } else {
            left_rec = &el->l_recs[index - 1];
            if (ocfs2_is_empty_extent(&el->l_recs[0]))
                  has_empty_extent = 1;
      }

      ret = ocfs2_path_bh_journal_access(handle, inode, right_path,
                                 path_num_items(right_path) - 1);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      if (has_empty_extent && index == 1) {
            /*
             * The easy case - we can just plop the record right in.
             */
            *left_rec = *split_rec;

            has_empty_extent = 0;
      } else
            le16_add_cpu(&left_rec->e_leaf_clusters, split_clusters);

      le32_add_cpu(&right_rec->e_cpos, split_clusters);
      le64_add_cpu(&right_rec->e_blkno,
                 ocfs2_clusters_to_blocks(inode->i_sb, split_clusters));
      le16_add_cpu(&right_rec->e_leaf_clusters, -split_clusters);

      ocfs2_cleanup_merge(el, index);

      ret = ocfs2_journal_dirty(handle, bh);
      if (ret)
            mlog_errno(ret);

      if (left_path) {
            ret = ocfs2_journal_dirty(handle, path_leaf_bh(left_path));
            if (ret)
                  mlog_errno(ret);

            /*
             * In the situation that the right_rec is empty and the extent
             * block is empty also,  ocfs2_complete_edge_insert can't handle
             * it and we need to delete the right extent block.
             */
            if (le16_to_cpu(right_rec->e_leaf_clusters) == 0 &&
                le16_to_cpu(el->l_next_free_rec) == 1) {

                  ret = ocfs2_remove_rightmost_path(inode, handle,
                                            right_path,
                                            dealloc, et);
                  if (ret) {
                        mlog_errno(ret);
                        goto out;
                  }

                  /* Now the rightmost extent block has been deleted.
                   * So we use the new rightmost path.
                   */
                  ocfs2_mv_path(right_path, left_path);
                  left_path = NULL;
            } else
                  ocfs2_complete_edge_insert(inode, handle, left_path,
                                       right_path, subtree_index);
      }
out:
      if (left_path)
            ocfs2_free_path(left_path);
      return ret;
}

static int ocfs2_try_to_merge_extent(struct inode *inode,
                             handle_t *handle,
                             struct ocfs2_path *path,
                             int split_index,
                             struct ocfs2_extent_rec *split_rec,
                             struct ocfs2_cached_dealloc_ctxt *dealloc,
                             struct ocfs2_merge_ctxt *ctxt,
                             struct ocfs2_extent_tree *et)

{
      int ret = 0;
      struct ocfs2_extent_list *el = path_leaf_el(path);
      struct ocfs2_extent_rec *rec = &el->l_recs[split_index];

      BUG_ON(ctxt->c_contig_type == CONTIG_NONE);

      if (ctxt->c_split_covers_rec && ctxt->c_has_empty_extent) {
            /*
             * The merge code will need to create an empty
             * extent to take the place of the newly
             * emptied slot. Remove any pre-existing empty
             * extents - having more than one in a leaf is
             * illegal.
             */
            ret = ocfs2_rotate_tree_left(inode, handle, path,
                                   dealloc, et);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }
            split_index--;
            rec = &el->l_recs[split_index];
      }

      if (ctxt->c_contig_type == CONTIG_LEFTRIGHT) {
            /*
             * Left-right contig implies this.
             */
            BUG_ON(!ctxt->c_split_covers_rec);

            /*
             * Since the leftright insert always covers the entire
             * extent, this call will delete the insert record
             * entirely, resulting in an empty extent record added to
             * the extent block.
             *
             * Since the adding of an empty extent shifts
             * everything back to the right, there's no need to
             * update split_index here.
             *
             * When the split_index is zero, we need to merge it to the
             * prevoius extent block. It is more efficient and easier
             * if we do merge_right first and merge_left later.
             */
            ret = ocfs2_merge_rec_right(inode, path,
                                  handle, split_rec,
                                  split_index);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            /*
             * We can only get this from logic error above.
             */
            BUG_ON(!ocfs2_is_empty_extent(&el->l_recs[0]));

            /* The merge left us with an empty extent, remove it. */
            ret = ocfs2_rotate_tree_left(inode, handle, path,
                                   dealloc, et);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            rec = &el->l_recs[split_index];

            /*
             * Note that we don't pass split_rec here on purpose -
             * we've merged it into the rec already.
             */
            ret = ocfs2_merge_rec_left(inode, path,
                                 handle, rec,
                                 dealloc, et,
                                 split_index);

            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            ret = ocfs2_rotate_tree_left(inode, handle, path,
                                   dealloc, et);
            /*
             * Error from this last rotate is not critical, so
             * print but don't bubble it up.
             */
            if (ret)
                  mlog_errno(ret);
            ret = 0;
      } else {
            /*
             * Merge a record to the left or right.
             *
             * 'contig_type' is relative to the existing record,
             * so for example, if we're "right contig", it's to
             * the record on the left (hence the left merge).
             */
            if (ctxt->c_contig_type == CONTIG_RIGHT) {
                  ret = ocfs2_merge_rec_left(inode,
                                       path,
                                       handle, split_rec,
                                       dealloc, et,
                                       split_index);
                  if (ret) {
                        mlog_errno(ret);
                        goto out;
                  }
            } else {
                  ret = ocfs2_merge_rec_right(inode,
                                        path,
                                        handle, split_rec,
                                        split_index);
                  if (ret) {
                        mlog_errno(ret);
                        goto out;
                  }
            }

            if (ctxt->c_split_covers_rec) {
                  /*
                   * The merge may have left an empty extent in
                   * our leaf. Try to rotate it away.
                   */
                  ret = ocfs2_rotate_tree_left(inode, handle, path,
                                         dealloc, et);
                  if (ret)
                        mlog_errno(ret);
                  ret = 0;
            }
      }

out:
      return ret;
}

static void ocfs2_subtract_from_rec(struct super_block *sb,
                            enum ocfs2_split_type split,
                            struct ocfs2_extent_rec *rec,
                            struct ocfs2_extent_rec *split_rec)
{
      u64 len_blocks;

      len_blocks = ocfs2_clusters_to_blocks(sb,
                        le16_to_cpu(split_rec->e_leaf_clusters));

      if (split == SPLIT_LEFT) {
            /*
             * Region is on the left edge of the existing
             * record.
             */
            le32_add_cpu(&rec->e_cpos,
                       le16_to_cpu(split_rec->e_leaf_clusters));
            le64_add_cpu(&rec->e_blkno, len_blocks);
            le16_add_cpu(&rec->e_leaf_clusters,
                       -le16_to_cpu(split_rec->e_leaf_clusters));
      } else {
            /*
             * Region is on the right edge of the existing
             * record.
             */
            le16_add_cpu(&rec->e_leaf_clusters,
                       -le16_to_cpu(split_rec->e_leaf_clusters));
      }
}

/*
 * Do the final bits of extent record insertion at the target leaf
 * list. If this leaf is part of an allocation tree, it is assumed
 * that the tree above has been prepared.
 */
static void ocfs2_insert_at_leaf(struct ocfs2_extent_rec *insert_rec,
                         struct ocfs2_extent_list *el,
                         struct ocfs2_insert_type *insert,
                         struct inode *inode)
{
      int i = insert->ins_contig_index;
      unsigned int range;
      struct ocfs2_extent_rec *rec;

      BUG_ON(le16_to_cpu(el->l_tree_depth) != 0);

      if (insert->ins_split != SPLIT_NONE) {
            i = ocfs2_search_extent_list(el, le32_to_cpu(insert_rec->e_cpos));
            BUG_ON(i == -1);
            rec = &el->l_recs[i];
            ocfs2_subtract_from_rec(inode->i_sb, insert->ins_split, rec,
                              insert_rec);
            goto rotate;
      }

      /*
       * Contiguous insert - either left or right.
       */
      if (insert->ins_contig != CONTIG_NONE) {
            rec = &el->l_recs[i];
            if (insert->ins_contig == CONTIG_LEFT) {
                  rec->e_blkno = insert_rec->e_blkno;
                  rec->e_cpos = insert_rec->e_cpos;
            }
            le16_add_cpu(&rec->e_leaf_clusters,
                       le16_to_cpu(insert_rec->e_leaf_clusters));
            return;
      }

      /*
       * Handle insert into an empty leaf.
       */
      if (le16_to_cpu(el->l_next_free_rec) == 0 ||
          ((le16_to_cpu(el->l_next_free_rec) == 1) &&
           ocfs2_is_empty_extent(&el->l_recs[0]))) {
            el->l_recs[0] = *insert_rec;
            el->l_next_free_rec = cpu_to_le16(1);
            return;
      }

      /*
       * Appending insert.
       */
      if (insert->ins_appending == APPEND_TAIL) {
            i = le16_to_cpu(el->l_next_free_rec) - 1;
            rec = &el->l_recs[i];
            range = le32_to_cpu(rec->e_cpos)
                  + le16_to_cpu(rec->e_leaf_clusters);
            BUG_ON(le32_to_cpu(insert_rec->e_cpos) < range);

            mlog_bug_on_msg(le16_to_cpu(el->l_next_free_rec) >=
                        le16_to_cpu(el->l_count),
                        "inode %lu, depth %u, count %u, next free %u, "
                        "rec.cpos %u, rec.clusters %u, "
                        "insert.cpos %u, insert.clusters %u\n",
                        inode->i_ino,
                        le16_to_cpu(el->l_tree_depth),
                        le16_to_cpu(el->l_count),
                        le16_to_cpu(el->l_next_free_rec),
                        le32_to_cpu(el->l_recs[i].e_cpos),
                        le16_to_cpu(el->l_recs[i].e_leaf_clusters),
                        le32_to_cpu(insert_rec->e_cpos),
                        le16_to_cpu(insert_rec->e_leaf_clusters));
            i++;
            el->l_recs[i] = *insert_rec;
            le16_add_cpu(&el->l_next_free_rec, 1);
            return;
      }

rotate:
      /*
       * Ok, we have to rotate.
       *
       * At this point, it is safe to assume that inserting into an
       * empty leaf and appending to a leaf have both been handled
       * above.
       *
       * This leaf needs to have space, either by the empty 1st
       * extent record, or by virtue of an l_next_rec < l_count.
       */
      ocfs2_rotate_leaf(el, insert_rec);
}

static void ocfs2_adjust_rightmost_records(struct inode *inode,
                                 handle_t *handle,
                                 struct ocfs2_path *path,
                                 struct ocfs2_extent_rec *insert_rec)
{
      int ret, i, next_free;
      struct buffer_head *bh;
      struct ocfs2_extent_list *el;
      struct ocfs2_extent_rec *rec;

      /*
       * Update everything except the leaf block.
       */
      for (i = 0; i < path->p_tree_depth; i++) {
            bh = path->p_node[i].bh;
            el = path->p_node[i].el;

            next_free = le16_to_cpu(el->l_next_free_rec);
            if (next_free == 0) {
                  ocfs2_error(inode->i_sb,
                            "Dinode %llu has a bad extent list",
                            (unsigned long long)OCFS2_I(inode)->ip_blkno);
                  ret = -EIO;
                  return;
            }

            rec = &el->l_recs[next_free - 1];

            rec->e_int_clusters = insert_rec->e_cpos;
            le32_add_cpu(&rec->e_int_clusters,
                       le16_to_cpu(insert_rec->e_leaf_clusters));
            le32_add_cpu(&rec->e_int_clusters,
                       -le32_to_cpu(rec->e_cpos));

            ret = ocfs2_journal_dirty(handle, bh);
            if (ret)
                  mlog_errno(ret);

      }
}

static int ocfs2_append_rec_to_path(struct inode *inode, handle_t *handle,
                            struct ocfs2_extent_rec *insert_rec,
                            struct ocfs2_path *right_path,
                            struct ocfs2_path **ret_left_path)
{
      int ret, next_free;
      struct ocfs2_extent_list *el;
      struct ocfs2_path *left_path = NULL;

      *ret_left_path = NULL;

      /*
       * This shouldn't happen for non-trees. The extent rec cluster
       * count manipulation below only works for interior nodes.
       */
      BUG_ON(right_path->p_tree_depth == 0);

      /*
       * If our appending insert is at the leftmost edge of a leaf,
       * then we might need to update the rightmost records of the
       * neighboring path.
       */
      el = path_leaf_el(right_path);
      next_free = le16_to_cpu(el->l_next_free_rec);
      if (next_free == 0 ||
          (next_free == 1 && ocfs2_is_empty_extent(&el->l_recs[0]))) {
            u32 left_cpos;

            ret = ocfs2_find_cpos_for_left_leaf(inode->i_sb, right_path,
                                        &left_cpos);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            mlog(0, "Append may need a left path update. cpos: %u, "
                 "left_cpos: %u\n", le32_to_cpu(insert_rec->e_cpos),
                 left_cpos);

            /*
             * No need to worry if the append is already in the
             * leftmost leaf.
             */
            if (left_cpos) {
                  left_path = ocfs2_new_path_from_path(right_path);
                  if (!left_path) {
                        ret = -ENOMEM;
                        mlog_errno(ret);
                        goto out;
                  }

                  ret = ocfs2_find_path(inode, left_path, left_cpos);
                  if (ret) {
                        mlog_errno(ret);
                        goto out;
                  }

                  /*
                   * ocfs2_insert_path() will pass the left_path to the
                   * journal for us.
                   */
            }
      }

      ret = ocfs2_journal_access_path(inode, handle, right_path);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      ocfs2_adjust_rightmost_records(inode, handle, right_path, insert_rec);

      *ret_left_path = left_path;
      ret = 0;
out:
      if (ret != 0)
            ocfs2_free_path(left_path);

      return ret;
}

static void ocfs2_split_record(struct inode *inode,
                         struct ocfs2_path *left_path,
                         struct ocfs2_path *right_path,
                         struct ocfs2_extent_rec *split_rec,
                         enum ocfs2_split_type split)
{
      int index;
      u32 cpos = le32_to_cpu(split_rec->e_cpos);
      struct ocfs2_extent_list *left_el = NULL, *right_el, *insert_el, *el;
      struct ocfs2_extent_rec *rec, *tmprec;

      right_el = path_leaf_el(right_path);
      if (left_path)
            left_el = path_leaf_el(left_path);

      el = right_el;
      insert_el = right_el;
      index = ocfs2_search_extent_list(el, cpos);
      if (index != -1) {
            if (index == 0 && left_path) {
                  BUG_ON(ocfs2_is_empty_extent(&el->l_recs[0]));

                  /*
                   * This typically means that the record
                   * started in the left path but moved to the
                   * right as a result of rotation. We either
                   * move the existing record to the left, or we
                   * do the later insert there.
                   *
                   * In this case, the left path should always
                   * exist as the rotate code will have passed
                   * it back for a post-insert update.
                   */

                  if (split == SPLIT_LEFT) {
                        /*
                         * It's a left split. Since we know
                         * that the rotate code gave us an
                         * empty extent in the left path, we
                         * can just do the insert there.
                         */
                        insert_el = left_el;
                  } else {
                        /*
                         * Right split - we have to move the
                         * existing record over to the left
                         * leaf. The insert will be into the
                         * newly created empty extent in the
                         * right leaf.
                         */
                        tmprec = &right_el->l_recs[index];
                        ocfs2_rotate_leaf(left_el, tmprec);
                        el = left_el;

                        memset(tmprec, 0, sizeof(*tmprec));
                        index = ocfs2_search_extent_list(left_el, cpos);
                        BUG_ON(index == -1);
                  }
            }
      } else {
            BUG_ON(!left_path);
            BUG_ON(!ocfs2_is_empty_extent(&left_el->l_recs[0]));
            /*
             * Left path is easy - we can just allow the insert to
             * happen.
             */
            el = left_el;
            insert_el = left_el;
            index = ocfs2_search_extent_list(el, cpos);
            BUG_ON(index == -1);
      }

      rec = &el->l_recs[index];
      ocfs2_subtract_from_rec(inode->i_sb, split, rec, split_rec);
      ocfs2_rotate_leaf(insert_el, split_rec);
}

/*
 * This function only does inserts on an allocation b-tree. For tree
 * depth = 0, ocfs2_insert_at_leaf() is called directly.
 *
 * right_path is the path we want to do the actual insert
 * in. left_path should only be passed in if we need to update that
 * portion of the tree after an edge insert.
 */
static int ocfs2_insert_path(struct inode *inode,
                       handle_t *handle,
                       struct ocfs2_path *left_path,
                       struct ocfs2_path *right_path,
                       struct ocfs2_extent_rec *insert_rec,
                       struct ocfs2_insert_type *insert)
{
      int ret, subtree_index;
      struct buffer_head *leaf_bh = path_leaf_bh(right_path);

      if (left_path) {
            int credits = handle->h_buffer_credits;

            /*
             * There's a chance that left_path got passed back to
             * us without being accounted for in the
             * journal. Extend our transaction here to be sure we
             * can change those blocks.
             */
            credits += left_path->p_tree_depth;

            ret = ocfs2_extend_trans(handle, credits);
            if (ret < 0) {
                  mlog_errno(ret);
                  goto out;
            }

            ret = ocfs2_journal_access_path(inode, handle, left_path);
            if (ret < 0) {
                  mlog_errno(ret);
                  goto out;
            }
      }

      /*
       * Pass both paths to the journal. The majority of inserts
       * will be touching all components anyway.
       */
      ret = ocfs2_journal_access_path(inode, handle, right_path);
      if (ret < 0) {
            mlog_errno(ret);
            goto out;
      }

      if (insert->ins_split != SPLIT_NONE) {
            /*
             * We could call ocfs2_insert_at_leaf() for some types
             * of splits, but it's easier to just let one separate
             * function sort it all out.
             */
            ocfs2_split_record(inode, left_path, right_path,
                           insert_rec, insert->ins_split);

            /*
             * Split might have modified either leaf and we don't
             * have a guarantee that the later edge insert will
             * dirty this for us.
             */
            if (left_path)
                  ret = ocfs2_journal_dirty(handle,
                                      path_leaf_bh(left_path));
                  if (ret)
                        mlog_errno(ret);
      } else
            ocfs2_insert_at_leaf(insert_rec, path_leaf_el(right_path),
                             insert, inode);

      ret = ocfs2_journal_dirty(handle, leaf_bh);
      if (ret)
            mlog_errno(ret);

      if (left_path) {
            /*
             * The rotate code has indicated that we need to fix
             * up portions of the tree after the insert.
             *
             * XXX: Should we extend the transaction here?
             */
            subtree_index = ocfs2_find_subtree_root(inode, left_path,
                                          right_path);
            ocfs2_complete_edge_insert(inode, handle, left_path,
                                 right_path, subtree_index);
      }

      ret = 0;
out:
      return ret;
}

static int ocfs2_do_insert_extent(struct inode *inode,
                          handle_t *handle,
                          struct ocfs2_extent_tree *et,
                          struct ocfs2_extent_rec *insert_rec,
                          struct ocfs2_insert_type *type)
{
      int ret, rotate = 0;
      u32 cpos;
      struct ocfs2_path *right_path = NULL;
      struct ocfs2_path *left_path = NULL;
      struct ocfs2_extent_list *el;

      el = et->et_root_el;

      ret = ocfs2_et_root_journal_access(handle, inode, et,
                                 OCFS2_JOURNAL_ACCESS_WRITE);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      if (le16_to_cpu(el->l_tree_depth) == 0) {
            ocfs2_insert_at_leaf(insert_rec, el, type, inode);
            goto out_update_clusters;
      }

      right_path = ocfs2_new_path_from_et(et);
      if (!right_path) {
            ret = -ENOMEM;
            mlog_errno(ret);
            goto out;
      }

      /*
       * Determine the path to start with. Rotations need the
       * rightmost path, everything else can go directly to the
       * target leaf.
       */
      cpos = le32_to_cpu(insert_rec->e_cpos);
      if (type->ins_appending == APPEND_NONE &&
          type->ins_contig == CONTIG_NONE) {
            rotate = 1;
            cpos = UINT_MAX;
      }

      ret = ocfs2_find_path(inode, right_path, cpos);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      /*
       * Rotations and appends need special treatment - they modify
       * parts of the tree's above them.
       *
       * Both might pass back a path immediate to the left of the
       * one being inserted to. This will be cause
       * ocfs2_insert_path() to modify the rightmost records of
       * left_path to account for an edge insert.
       *
       * XXX: When modifying this code, keep in mind that an insert
       * can wind up skipping both of these two special cases...
       */
      if (rotate) {
            ret = ocfs2_rotate_tree_right(inode, handle, type->ins_split,
                                    le32_to_cpu(insert_rec->e_cpos),
                                    right_path, &left_path);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            /*
             * ocfs2_rotate_tree_right() might have extended the
             * transaction without re-journaling our tree root.
             */
            ret = ocfs2_et_root_journal_access(handle, inode, et,
                                       OCFS2_JOURNAL_ACCESS_WRITE);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }
      } else if (type->ins_appending == APPEND_TAIL
               && type->ins_contig != CONTIG_LEFT) {
            ret = ocfs2_append_rec_to_path(inode, handle, insert_rec,
                                     right_path, &left_path);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }
      }

      ret = ocfs2_insert_path(inode, handle, left_path, right_path,
                        insert_rec, type);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

out_update_clusters:
      if (type->ins_split == SPLIT_NONE)
            ocfs2_et_update_clusters(inode, et,
                               le16_to_cpu(insert_rec->e_leaf_clusters));

      ret = ocfs2_journal_dirty(handle, et->et_root_bh);
      if (ret)
            mlog_errno(ret);

out:
      ocfs2_free_path(left_path);
      ocfs2_free_path(right_path);

      return ret;
}

static enum ocfs2_contig_type
ocfs2_figure_merge_contig_type(struct inode *inode, struct ocfs2_path *path,
                         struct ocfs2_extent_list *el, int index,
                         struct ocfs2_extent_rec *split_rec)
{
      int status;
      enum ocfs2_contig_type ret = CONTIG_NONE;
      u32 left_cpos, right_cpos;
      struct ocfs2_extent_rec *rec = NULL;
      struct ocfs2_extent_list *new_el;
      struct ocfs2_path *left_path = NULL, *right_path = NULL;
      struct buffer_head *bh;
      struct ocfs2_extent_block *eb;

      if (index > 0) {
            rec = &el->l_recs[index - 1];
      } else if (path->p_tree_depth > 0) {
            status = ocfs2_find_cpos_for_left_leaf(inode->i_sb,
                                           path, &left_cpos);
            if (status)
                  goto out;

            if (left_cpos != 0) {
                  left_path = ocfs2_new_path_from_path(path);
                  if (!left_path)
                        goto out;

                  status = ocfs2_find_path(inode, left_path, left_cpos);
                  if (status)
                        goto out;

                  new_el = path_leaf_el(left_path);

                  if (le16_to_cpu(new_el->l_next_free_rec) !=
                      le16_to_cpu(new_el->l_count)) {
                        bh = path_leaf_bh(left_path);
                        eb = (struct ocfs2_extent_block *)bh->b_data;
                        ocfs2_error(inode->i_sb,
                                  "Extent block #%llu has an "
                                  "invalid l_next_free_rec of "
                                  "%d.  It should have "
                                  "matched the l_count of %d",
                                  (unsigned long long)le64_to_cpu(eb->h_blkno),
                                  le16_to_cpu(new_el->l_next_free_rec),
                                  le16_to_cpu(new_el->l_count));
                        status = -EINVAL;
                        goto out;
                  }
                  rec = &new_el->l_recs[
                        le16_to_cpu(new_el->l_next_free_rec) - 1];
            }
      }

      /*
       * We're careful to check for an empty extent record here -
       * the merge code will know what to do if it sees one.
       */
      if (rec) {
            if (index == 1 && ocfs2_is_empty_extent(rec)) {
                  if (split_rec->e_cpos == el->l_recs[index].e_cpos)
                        ret = CONTIG_RIGHT;
            } else {
                  ret = ocfs2_extent_contig(inode, rec, split_rec);
            }
      }

      rec = NULL;
      if (index < (le16_to_cpu(el->l_next_free_rec) - 1))
            rec = &el->l_recs[index + 1];
      else if (le16_to_cpu(el->l_next_free_rec) == le16_to_cpu(el->l_count) &&
             path->p_tree_depth > 0) {
            status = ocfs2_find_cpos_for_right_leaf(inode->i_sb,
                                          path, &right_cpos);
            if (status)
                  goto out;

            if (right_cpos == 0)
                  goto out;

            right_path = ocfs2_new_path_from_path(path);
            if (!right_path)
                  goto out;

            status = ocfs2_find_path(inode, right_path, right_cpos);
            if (status)
                  goto out;

            new_el = path_leaf_el(right_path);
            rec = &new_el->l_recs[0];
            if (ocfs2_is_empty_extent(rec)) {
                  if (le16_to_cpu(new_el->l_next_free_rec) <= 1) {
                        bh = path_leaf_bh(right_path);
                        eb = (struct ocfs2_extent_block *)bh->b_data;
                        ocfs2_error(inode->i_sb,
                                  "Extent block #%llu has an "
                                  "invalid l_next_free_rec of %d",
                                  (unsigned long long)le64_to_cpu(eb->h_blkno),
                                  le16_to_cpu(new_el->l_next_free_rec));
                        status = -EINVAL;
                        goto out;
                  }
                  rec = &new_el->l_recs[1];
            }
      }

      if (rec) {
            enum ocfs2_contig_type contig_type;

            contig_type = ocfs2_extent_contig(inode, rec, split_rec);

            if (contig_type == CONTIG_LEFT && ret == CONTIG_RIGHT)
                  ret = CONTIG_LEFTRIGHT;
            else if (ret == CONTIG_NONE)
                  ret = contig_type;
      }

out:
      if (left_path)
            ocfs2_free_path(left_path);
      if (right_path)
            ocfs2_free_path(right_path);

      return ret;
}

static void ocfs2_figure_contig_type(struct inode *inode,
                             struct ocfs2_insert_type *insert,
                             struct ocfs2_extent_list *el,
                             struct ocfs2_extent_rec *insert_rec,
                             struct ocfs2_extent_tree *et)
{
      int i;
      enum ocfs2_contig_type contig_type = CONTIG_NONE;

      BUG_ON(le16_to_cpu(el->l_tree_depth) != 0);

      for(i = 0; i < le16_to_cpu(el->l_next_free_rec); i++) {
            contig_type = ocfs2_extent_contig(inode, &el->l_recs[i],
                                      insert_rec);
            if (contig_type != CONTIG_NONE) {
                  insert->ins_contig_index = i;
                  break;
            }
      }
      insert->ins_contig = contig_type;

      if (insert->ins_contig != CONTIG_NONE) {
            struct ocfs2_extent_rec *rec =
                        &el->l_recs[insert->ins_contig_index];
            unsigned int len = le16_to_cpu(rec->e_leaf_clusters) +
                           le16_to_cpu(insert_rec->e_leaf_clusters);

            /*
             * Caller might want us to limit the size of extents, don't
             * calculate contiguousness if we might exceed that limit.
             */
            if (et->et_max_leaf_clusters &&
                (len > et->et_max_leaf_clusters))
                  insert->ins_contig = CONTIG_NONE;
      }
}

/*
 * This should only be called against the righmost leaf extent list.
 *
 * ocfs2_figure_appending_type() will figure out whether we'll have to
 * insert at the tail of the rightmost leaf.
 *
 * This should also work against the root extent list for tree's with 0
 * depth. If we consider the root extent list to be the rightmost leaf node
 * then the logic here makes sense.
 */
static void ocfs2_figure_appending_type(struct ocfs2_insert_type *insert,
                              struct ocfs2_extent_list *el,
                              struct ocfs2_extent_rec *insert_rec)
{
      int i;
      u32 cpos = le32_to_cpu(insert_rec->e_cpos);
      struct ocfs2_extent_rec *rec;

      insert->ins_appending = APPEND_NONE;

      BUG_ON(le16_to_cpu(el->l_tree_depth) != 0);

      if (!el->l_next_free_rec)
            goto set_tail_append;

      if (ocfs2_is_empty_extent(&el->l_recs[0])) {
            /* Were all records empty? */
            if (le16_to_cpu(el->l_next_free_rec) == 1)
                  goto set_tail_append;
      }

      i = le16_to_cpu(el->l_next_free_rec) - 1;
      rec = &el->l_recs[i];

      if (cpos >=
          (le32_to_cpu(rec->e_cpos) + le16_to_cpu(rec->e_leaf_clusters)))
            goto set_tail_append;

      return;

set_tail_append:
      insert->ins_appending = APPEND_TAIL;
}

/*
 * Helper function called at the begining of an insert.
 *
 * This computes a few things that are commonly used in the process of
 * inserting into the btree:
 *   - Whether the new extent is contiguous with an existing one.
 *   - The current tree depth.
 *   - Whether the insert is an appending one.
 *   - The total # of free records in the tree.
 *
 * All of the information is stored on the ocfs2_insert_type
 * structure.
 */
static int ocfs2_figure_insert_type(struct inode *inode,
                            struct ocfs2_extent_tree *et,
                            struct buffer_head **last_eb_bh,
                            struct ocfs2_extent_rec *insert_rec,
                            int *free_records,
                            struct ocfs2_insert_type *insert)
{
      int ret;
      struct ocfs2_extent_block *eb;
      struct ocfs2_extent_list *el;
      struct ocfs2_path *path = NULL;
      struct buffer_head *bh = NULL;

      insert->ins_split = SPLIT_NONE;

      el = et->et_root_el;
      insert->ins_tree_depth = le16_to_cpu(el->l_tree_depth);

      if (el->l_tree_depth) {
            /*
             * If we have tree depth, we read in the
             * rightmost extent block ahead of time as
             * ocfs2_figure_insert_type() and ocfs2_add_branch()
             * may want it later.
             */
            ret = ocfs2_read_extent_block(inode,
                                    ocfs2_et_get_last_eb_blk(et),
                                    &bh);
            if (ret) {
                  mlog_exit(ret);
                  goto out;
            }
            eb = (struct ocfs2_extent_block *) bh->b_data;
            el = &eb->h_list;
      }

      /*
       * Unless we have a contiguous insert, we'll need to know if
       * there is room left in our allocation tree for another
       * extent record.
       *
       * XXX: This test is simplistic, we can search for empty
       * extent records too.
       */
      *free_records = le16_to_cpu(el->l_count) -
            le16_to_cpu(el->l_next_free_rec);

      if (!insert->ins_tree_depth) {
            ocfs2_figure_contig_type(inode, insert, el, insert_rec, et);
            ocfs2_figure_appending_type(insert, el, insert_rec);
            return 0;
      }

      path = ocfs2_new_path_from_et(et);
      if (!path) {
            ret = -ENOMEM;
            mlog_errno(ret);
            goto out;
      }

      /*
       * In the case that we're inserting past what the tree
       * currently accounts for, ocfs2_find_path() will return for
       * us the rightmost tree path. This is accounted for below in
       * the appending code.
       */
      ret = ocfs2_find_path(inode, path, le32_to_cpu(insert_rec->e_cpos));
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      el = path_leaf_el(path);

      /*
       * Now that we have the path, there's two things we want to determine:
       * 1) Contiguousness (also set contig_index if this is so)
       *
       * 2) Are we doing an append? We can trivially break this up
         *     into two types of appends: simple record append, or a
         *     rotate inside the tail leaf.
       */
      ocfs2_figure_contig_type(inode, insert, el, insert_rec, et);

      /*
       * The insert code isn't quite ready to deal with all cases of
       * left contiguousness. Specifically, if it's an insert into
       * the 1st record in a leaf, it will require the adjustment of
       * cluster count on the last record of the path directly to it's
       * left. For now, just catch that case and fool the layers
       * above us. This works just fine for tree_depth == 0, which
       * is why we allow that above.
       */
      if (insert->ins_contig == CONTIG_LEFT &&
          insert->ins_contig_index == 0)
            insert->ins_contig = CONTIG_NONE;

      /*
       * Ok, so we can simply compare against last_eb to figure out
       * whether the path doesn't exist. This will only happen in
       * the case that we're doing a tail append, so maybe we can
       * take advantage of that information somehow.
       */
      if (ocfs2_et_get_last_eb_blk(et) ==
          path_leaf_bh(path)->b_blocknr) {
            /*
             * Ok, ocfs2_find_path() returned us the rightmost
             * tree path. This might be an appending insert. There are
             * two cases:
             *    1) We're doing a true append at the tail:
             *    -This might even be off the end of the leaf
             *    2) We're "appending" by rotating in the tail
             */
            ocfs2_figure_appending_type(insert, el, insert_rec);
      }

out:
      ocfs2_free_path(path);

      if (ret == 0)
            *last_eb_bh = bh;
      else
            brelse(bh);
      return ret;
}

/*
 * Insert an extent into an inode btree.
 *
 * The caller needs to update fe->i_clusters
 */
int ocfs2_insert_extent(struct ocfs2_super *osb,
                  handle_t *handle,
                  struct inode *inode,
                  struct ocfs2_extent_tree *et,
                  u32 cpos,
                  u64 start_blk,
                  u32 new_clusters,
                  u8 flags,
                  struct ocfs2_alloc_context *meta_ac)
{
      int status;
      int uninitialized_var(free_records);
      struct buffer_head *last_eb_bh = NULL;
      struct ocfs2_insert_type insert = {0, };
      struct ocfs2_extent_rec rec;

      mlog(0, "add %u clusters at position %u to inode %llu\n",
           new_clusters, cpos, (unsigned long long)OCFS2_I(inode)->ip_blkno);

      memset(&rec, 0, sizeof(rec));
      rec.e_cpos = cpu_to_le32(cpos);
      rec.e_blkno = cpu_to_le64(start_blk);
      rec.e_leaf_clusters = cpu_to_le16(new_clusters);
      rec.e_flags = flags;
      status = ocfs2_et_insert_check(inode, et, &rec);
      if (status) {
            mlog_errno(status);
            goto bail;
      }

      status = ocfs2_figure_insert_type(inode, et, &last_eb_bh, &rec,
                                &free_records, &insert);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

      mlog(0, "Insert.appending: %u, Insert.Contig: %u, "
           "Insert.contig_index: %d, Insert.free_records: %d, "
           "Insert.tree_depth: %d\n",
           insert.ins_appending, insert.ins_contig, insert.ins_contig_index,
           free_records, insert.ins_tree_depth);

      if (insert.ins_contig == CONTIG_NONE && free_records == 0) {
            status = ocfs2_grow_tree(inode, handle, et,
                               &insert.ins_tree_depth, &last_eb_bh,
                               meta_ac);
            if (status) {
                  mlog_errno(status);
                  goto bail;
            }
      }

      /* Finally, we can add clusters. This might rotate the tree for us. */
      status = ocfs2_do_insert_extent(inode, handle, et, &rec, &insert);
      if (status < 0)
            mlog_errno(status);
      else if (et->et_ops == &ocfs2_dinode_et_ops)
            ocfs2_extent_map_insert_rec(inode, &rec);

bail:
      brelse(last_eb_bh);

      mlog_exit(status);
      return status;
}

/*
 * Allcate and add clusters into the extent b-tree.
 * The new clusters(clusters_to_add) will be inserted at logical_offset.
 * The extent b-tree's root is specified by et, and
 * it is not limited to the file storage. Any extent tree can use this
 * function if it implements the proper ocfs2_extent_tree.
 */
int ocfs2_add_clusters_in_btree(struct ocfs2_super *osb,
                        struct inode *inode,
                        u32 *logical_offset,
                        u32 clusters_to_add,
                        int mark_unwritten,
                        struct ocfs2_extent_tree *et,
                        handle_t *handle,
                        struct ocfs2_alloc_context *data_ac,
                        struct ocfs2_alloc_context *meta_ac,
                        enum ocfs2_alloc_restarted *reason_ret)
{
      int status = 0;
      int free_extents;
      enum ocfs2_alloc_restarted reason = RESTART_NONE;
      u32 bit_off, num_bits;
      u64 block;
      u8 flags = 0;

      BUG_ON(!clusters_to_add);

      if (mark_unwritten)
            flags = OCFS2_EXT_UNWRITTEN;

      free_extents = ocfs2_num_free_extents(osb, inode, et);
      if (free_extents < 0) {
            status = free_extents;
            mlog_errno(status);
            goto leave;
      }

      /* there are two cases which could cause us to EAGAIN in the
       * we-need-more-metadata case:
       * 1) we haven't reserved *any*
       * 2) we are so fragmented, we've needed to add metadata too
       *    many times. */
      if (!free_extents && !meta_ac) {
            mlog(0, "we haven't reserved any metadata!\n");
            status = -EAGAIN;
            reason = RESTART_META;
            goto leave;
      } else if ((!free_extents)
               && (ocfs2_alloc_context_bits_left(meta_ac)
                   < ocfs2_extend_meta_needed(et->et_root_el))) {
            mlog(0, "filesystem is really fragmented...\n");
            status = -EAGAIN;
            reason = RESTART_META;
            goto leave;
      }

      status = __ocfs2_claim_clusters(osb, handle, data_ac, 1,
                              clusters_to_add, &bit_off, &num_bits);
      if (status < 0) {
            if (status != -ENOSPC)
                  mlog_errno(status);
            goto leave;
      }

      BUG_ON(num_bits > clusters_to_add);

      /* reserve our write early -- insert_extent may update the tree root */
      status = ocfs2_et_root_journal_access(handle, inode, et,
                                    OCFS2_JOURNAL_ACCESS_WRITE);
      if (status < 0) {
            mlog_errno(status);
            goto leave;
      }

      block = ocfs2_clusters_to_blocks(osb->sb, bit_off);
      mlog(0, "Allocating %u clusters at block %u for inode %llu\n",
           num_bits, bit_off, (unsigned long long)OCFS2_I(inode)->ip_blkno);
      status = ocfs2_insert_extent(osb, handle, inode, et,
                             *logical_offset, block,
                             num_bits, flags, meta_ac);
      if (status < 0) {
            mlog_errno(status);
            goto leave;
      }

      status = ocfs2_journal_dirty(handle, et->et_root_bh);
      if (status < 0) {
            mlog_errno(status);
            goto leave;
      }

      clusters_to_add -= num_bits;
      *logical_offset += num_bits;

      if (clusters_to_add) {
            mlog(0, "need to alloc once more, wanted = %u\n",
                 clusters_to_add);
            status = -EAGAIN;
            reason = RESTART_TRANS;
      }

leave:
      mlog_exit(status);
      if (reason_ret)
            *reason_ret = reason;
      return status;
}

static void ocfs2_make_right_split_rec(struct super_block *sb,
                               struct ocfs2_extent_rec *split_rec,
                               u32 cpos,
                               struct ocfs2_extent_rec *rec)
{
      u32 rec_cpos = le32_to_cpu(rec->e_cpos);
      u32 rec_range = rec_cpos + le16_to_cpu(rec->e_leaf_clusters);

      memset(split_rec, 0, sizeof(struct ocfs2_extent_rec));

      split_rec->e_cpos = cpu_to_le32(cpos);
      split_rec->e_leaf_clusters = cpu_to_le16(rec_range - cpos);

      split_rec->e_blkno = rec->e_blkno;
      le64_add_cpu(&split_rec->e_blkno,
                 ocfs2_clusters_to_blocks(sb, cpos - rec_cpos));

      split_rec->e_flags = rec->e_flags;
}

static int ocfs2_split_and_insert(struct inode *inode,
                          handle_t *handle,
                          struct ocfs2_path *path,
                          struct ocfs2_extent_tree *et,
                          struct buffer_head **last_eb_bh,
                          int split_index,
                          struct ocfs2_extent_rec *orig_split_rec,
                          struct ocfs2_alloc_context *meta_ac)
{
      int ret = 0, depth;
      unsigned int insert_range, rec_range, do_leftright = 0;
      struct ocfs2_extent_rec tmprec;
      struct ocfs2_extent_list *rightmost_el;
      struct ocfs2_extent_rec rec;
      struct ocfs2_extent_rec split_rec = *orig_split_rec;
      struct ocfs2_insert_type insert;
      struct ocfs2_extent_block *eb;

leftright:
      /*
       * Store a copy of the record on the stack - it might move
       * around as the tree is manipulated below.
       */
      rec = path_leaf_el(path)->l_recs[split_index];

      rightmost_el = et->et_root_el;

      depth = le16_to_cpu(rightmost_el->l_tree_depth);
      if (depth) {
            BUG_ON(!(*last_eb_bh));
            eb = (struct ocfs2_extent_block *) (*last_eb_bh)->b_data;
            rightmost_el = &eb->h_list;
      }

      if (le16_to_cpu(rightmost_el->l_next_free_rec) ==
          le16_to_cpu(rightmost_el->l_count)) {
            ret = ocfs2_grow_tree(inode, handle, et,
                              &depth, last_eb_bh, meta_ac);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }
      }

      memset(&insert, 0, sizeof(struct ocfs2_insert_type));
      insert.ins_appending = APPEND_NONE;
      insert.ins_contig = CONTIG_NONE;
      insert.ins_tree_depth = depth;

      insert_range = le32_to_cpu(split_rec.e_cpos) +
            le16_to_cpu(split_rec.e_leaf_clusters);
      rec_range = le32_to_cpu(rec.e_cpos) +
            le16_to_cpu(rec.e_leaf_clusters);

      if (split_rec.e_cpos == rec.e_cpos) {
            insert.ins_split = SPLIT_LEFT;
      } else if (insert_range == rec_range) {
            insert.ins_split = SPLIT_RIGHT;
      } else {
            /*
             * Left/right split. We fake this as a right split
             * first and then make a second pass as a left split.
             */
            insert.ins_split = SPLIT_RIGHT;

            ocfs2_make_right_split_rec(inode->i_sb, &tmprec, insert_range,
                                 &rec);

            split_rec = tmprec;

            BUG_ON(do_leftright);
            do_leftright = 1;
      }

      ret = ocfs2_do_insert_extent(inode, handle, et, &split_rec, &insert);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      if (do_leftright == 1) {
            u32 cpos;
            struct ocfs2_extent_list *el;

            do_leftright++;
            split_rec = *orig_split_rec;

            ocfs2_reinit_path(path, 1);

            cpos = le32_to_cpu(split_rec.e_cpos);
            ret = ocfs2_find_path(inode, path, cpos);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            el = path_leaf_el(path);
            split_index = ocfs2_search_extent_list(el, cpos);
            goto leftright;
      }
out:

      return ret;
}

static int ocfs2_replace_extent_rec(struct inode *inode,
                            handle_t *handle,
                            struct ocfs2_path *path,
                            struct ocfs2_extent_list *el,
                            int split_index,
                            struct ocfs2_extent_rec *split_rec)
{
      int ret;

      ret = ocfs2_path_bh_journal_access(handle, inode, path,
                                 path_num_items(path) - 1);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      el->l_recs[split_index] = *split_rec;

      ocfs2_journal_dirty(handle, path_leaf_bh(path));
out:
      return ret;
}

/*
 * Mark part or all of the extent record at split_index in the leaf
 * pointed to by path as written. This removes the unwritten
 * extent flag.
 *
 * Care is taken to handle contiguousness so as to not grow the tree.
 *
 * meta_ac is not strictly necessary - we only truly need it if growth
 * of the tree is required. All other cases will degrade into a less
 * optimal tree layout.
 *
 * last_eb_bh should be the rightmost leaf block for any extent
 * btree. Since a split may grow the tree or a merge might shrink it,
 * the caller cannot trust the contents of that buffer after this call.
 *
 * This code is optimized for readability - several passes might be
 * made over certain portions of the tree. All of those blocks will
 * have been brought into cache (and pinned via the journal), so the
 * extra overhead is not expressed in terms of disk reads.
 */
static int __ocfs2_mark_extent_written(struct inode *inode,
                               struct ocfs2_extent_tree *et,
                               handle_t *handle,
                               struct ocfs2_path *path,
                               int split_index,
                               struct ocfs2_extent_rec *split_rec,
                               struct ocfs2_alloc_context *meta_ac,
                               struct ocfs2_cached_dealloc_ctxt *dealloc)
{
      int ret = 0;
      struct ocfs2_extent_list *el = path_leaf_el(path);
      struct buffer_head *last_eb_bh = NULL;
      struct ocfs2_extent_rec *rec = &el->l_recs[split_index];
      struct ocfs2_merge_ctxt ctxt;
      struct ocfs2_extent_list *rightmost_el;

      if (!(rec->e_flags & OCFS2_EXT_UNWRITTEN)) {
            ret = -EIO;
            mlog_errno(ret);
            goto out;
      }

      if (le32_to_cpu(rec->e_cpos) > le32_to_cpu(split_rec->e_cpos) ||
          ((le32_to_cpu(rec->e_cpos) + le16_to_cpu(rec->e_leaf_clusters)) <
           (le32_to_cpu(split_rec->e_cpos) + le16_to_cpu(split_rec->e_leaf_clusters)))) {
            ret = -EIO;
            mlog_errno(ret);
            goto out;
      }

      ctxt.c_contig_type = ocfs2_figure_merge_contig_type(inode, path, el,
                                              split_index,
                                              split_rec);

      /*
       * The core merge / split code wants to know how much room is
       * left in this inodes allocation tree, so we pass the
       * rightmost extent list.
       */
      if (path->p_tree_depth) {
            struct ocfs2_extent_block *eb;

            ret = ocfs2_read_extent_block(inode,
                                    ocfs2_et_get_last_eb_blk(et),
                                    &last_eb_bh);
            if (ret) {
                  mlog_exit(ret);
                  goto out;
            }

            eb = (struct ocfs2_extent_block *) last_eb_bh->b_data;
            rightmost_el = &eb->h_list;
      } else
            rightmost_el = path_root_el(path);

      if (rec->e_cpos == split_rec->e_cpos &&
          rec->e_leaf_clusters == split_rec->e_leaf_clusters)
            ctxt.c_split_covers_rec = 1;
      else
            ctxt.c_split_covers_rec = 0;

      ctxt.c_has_empty_extent = ocfs2_is_empty_extent(&el->l_recs[0]);

      mlog(0, "index: %d, contig: %u, has_empty: %u, split_covers: %u\n",
           split_index, ctxt.c_contig_type, ctxt.c_has_empty_extent,
           ctxt.c_split_covers_rec);

      if (ctxt.c_contig_type == CONTIG_NONE) {
            if (ctxt.c_split_covers_rec)
                  ret = ocfs2_replace_extent_rec(inode, handle,
                                           path, el,
                                           split_index, split_rec);
            else
                  ret = ocfs2_split_and_insert(inode, handle, path, et,
                                         &last_eb_bh, split_index,
                                         split_rec, meta_ac);
            if (ret)
                  mlog_errno(ret);
      } else {
            ret = ocfs2_try_to_merge_extent(inode, handle, path,
                                    split_index, split_rec,
                                    dealloc, &ctxt, et);
            if (ret)
                  mlog_errno(ret);
      }

out:
      brelse(last_eb_bh);
      return ret;
}

/*
 * Mark the already-existing extent at cpos as written for len clusters.
 *
 * If the existing extent is larger than the request, initiate a
 * split. An attempt will be made at merging with adjacent extents.
 *
 * The caller is responsible for passing down meta_ac if we'll need it.
 */
int ocfs2_mark_extent_written(struct inode *inode,
                        struct ocfs2_extent_tree *et,
                        handle_t *handle, u32 cpos, u32 len, u32 phys,
                        struct ocfs2_alloc_context *meta_ac,
                        struct ocfs2_cached_dealloc_ctxt *dealloc)
{
      int ret, index;
      u64 start_blkno = ocfs2_clusters_to_blocks(inode->i_sb, phys);
      struct ocfs2_extent_rec split_rec;
      struct ocfs2_path *left_path = NULL;
      struct ocfs2_extent_list *el;

      mlog(0, "Inode %lu cpos %u, len %u, phys %u (%llu)\n",
           inode->i_ino, cpos, len, phys, (unsigned long long)start_blkno);

      if (!ocfs2_writes_unwritten_extents(OCFS2_SB(inode->i_sb))) {
            ocfs2_error(inode->i_sb, "Inode %llu has unwritten extents "
                      "that are being written to, but the feature bit "
                      "is not set in the super block.",
                      (unsigned long long)OCFS2_I(inode)->ip_blkno);
            ret = -EROFS;
            goto out;
      }

      /*
       * XXX: This should be fixed up so that we just re-insert the
       * next extent records.
       *
       * XXX: This is a hack on the extent tree, maybe it should be
       * an op?
       */
      if (et->et_ops == &ocfs2_dinode_et_ops)
            ocfs2_extent_map_trunc(inode, 0);

      left_path = ocfs2_new_path_from_et(et);
      if (!left_path) {
            ret = -ENOMEM;
            mlog_errno(ret);
            goto out;
      }

      ret = ocfs2_find_path(inode, left_path, cpos);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }
      el = path_leaf_el(left_path);

      index = ocfs2_search_extent_list(el, cpos);
      if (index == -1 || index >= le16_to_cpu(el->l_next_free_rec)) {
            ocfs2_error(inode->i_sb,
                      "Inode %llu has an extent at cpos %u which can no "
                      "longer be found.\n",
                      (unsigned long long)OCFS2_I(inode)->ip_blkno, cpos);
            ret = -EROFS;
            goto out;
      }

      memset(&split_rec, 0, sizeof(struct ocfs2_extent_rec));
      split_rec.e_cpos = cpu_to_le32(cpos);
      split_rec.e_leaf_clusters = cpu_to_le16(len);
      split_rec.e_blkno = cpu_to_le64(start_blkno);
      split_rec.e_flags = path_leaf_el(left_path)->l_recs[index].e_flags;
      split_rec.e_flags &= ~OCFS2_EXT_UNWRITTEN;

      ret = __ocfs2_mark_extent_written(inode, et, handle, left_path,
                                index, &split_rec, meta_ac,
                                dealloc);
      if (ret)
            mlog_errno(ret);

out:
      ocfs2_free_path(left_path);
      return ret;
}

static int ocfs2_split_tree(struct inode *inode, struct ocfs2_extent_tree *et,
                      handle_t *handle, struct ocfs2_path *path,
                      int index, u32 new_range,
                      struct ocfs2_alloc_context *meta_ac)
{
      int ret, depth, credits = handle->h_buffer_credits;
      struct buffer_head *last_eb_bh = NULL;
      struct ocfs2_extent_block *eb;
      struct ocfs2_extent_list *rightmost_el, *el;
      struct ocfs2_extent_rec split_rec;
      struct ocfs2_extent_rec *rec;
      struct ocfs2_insert_type insert;

      /*
       * Setup the record to split before we grow the tree.
       */
      el = path_leaf_el(path);
      rec = &el->l_recs[index];
      ocfs2_make_right_split_rec(inode->i_sb, &split_rec, new_range, rec);

      depth = path->p_tree_depth;
      if (depth > 0) {
            ret = ocfs2_read_extent_block(inode,
                                    ocfs2_et_get_last_eb_blk(et),
                                    &last_eb_bh);
            if (ret < 0) {
                  mlog_errno(ret);
                  goto out;
            }

            eb = (struct ocfs2_extent_block *) last_eb_bh->b_data;
            rightmost_el = &eb->h_list;
      } else
            rightmost_el = path_leaf_el(path);

      credits += path->p_tree_depth +
               ocfs2_extend_meta_needed(et->et_root_el);
      ret = ocfs2_extend_trans(handle, credits);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      if (le16_to_cpu(rightmost_el->l_next_free_rec) ==
          le16_to_cpu(rightmost_el->l_count)) {
            ret = ocfs2_grow_tree(inode, handle, et, &depth, &last_eb_bh,
                              meta_ac);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }
      }

      memset(&insert, 0, sizeof(struct ocfs2_insert_type));
      insert.ins_appending = APPEND_NONE;
      insert.ins_contig = CONTIG_NONE;
      insert.ins_split = SPLIT_RIGHT;
      insert.ins_tree_depth = depth;

      ret = ocfs2_do_insert_extent(inode, handle, et, &split_rec, &insert);
      if (ret)
            mlog_errno(ret);

out:
      brelse(last_eb_bh);
      return ret;
}

static int ocfs2_truncate_rec(struct inode *inode, handle_t *handle,
                        struct ocfs2_path *path, int index,
                        struct ocfs2_cached_dealloc_ctxt *dealloc,
                        u32 cpos, u32 len,
                        struct ocfs2_extent_tree *et)
{
      int ret;
      u32 left_cpos, rec_range, trunc_range;
      int wants_rotate = 0, is_rightmost_tree_rec = 0;
      struct super_block *sb = inode->i_sb;
      struct ocfs2_path *left_path = NULL;
      struct ocfs2_extent_list *el = path_leaf_el(path);
      struct ocfs2_extent_rec *rec;
      struct ocfs2_extent_block *eb;

      if (ocfs2_is_empty_extent(&el->l_recs[0]) && index > 0) {
            ret = ocfs2_rotate_tree_left(inode, handle, path, dealloc, et);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            index--;
      }

      if (index == (le16_to_cpu(el->l_next_free_rec) - 1) &&
          path->p_tree_depth) {
            /*
             * Check whether this is the rightmost tree record. If
             * we remove all of this record or part of its right
             * edge then an update of the record lengths above it
             * will be required.
             */
            eb = (struct ocfs2_extent_block *)path_leaf_bh(path)->b_data;
            if (eb->h_next_leaf_blk == 0)
                  is_rightmost_tree_rec = 1;
      }

      rec = &el->l_recs[index];
      if (index == 0 && path->p_tree_depth &&
          le32_to_cpu(rec->e_cpos) == cpos) {
            /*
             * Changing the leftmost offset (via partial or whole
             * record truncate) of an interior (or rightmost) path
             * means we have to update the subtree that is formed
             * by this leaf and the one to it's left.
             *
             * There are two cases we can skip:
             *   1) Path is the leftmost one in our inode tree.
             *   2) The leaf is rightmost and will be empty after
             *      we remove the extent record - the rotate code
             *      knows how to update the newly formed edge.
             */

            ret = ocfs2_find_cpos_for_left_leaf(inode->i_sb, path,
                                        &left_cpos);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            if (left_cpos && le16_to_cpu(el->l_next_free_rec) > 1) {
                  left_path = ocfs2_new_path_from_path(path);
                  if (!left_path) {
                        ret = -ENOMEM;
                        mlog_errno(ret);
                        goto out;
                  }

                  ret = ocfs2_find_path(inode, left_path, left_cpos);
                  if (ret) {
                        mlog_errno(ret);
                        goto out;
                  }
            }
      }

      ret = ocfs2_extend_rotate_transaction(handle, 0,
                                    handle->h_buffer_credits,
                                    path);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      ret = ocfs2_journal_access_path(inode, handle, path);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      ret = ocfs2_journal_access_path(inode, handle, left_path);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      rec_range = le32_to_cpu(rec->e_cpos) + ocfs2_rec_clusters(el, rec);
      trunc_range = cpos + len;

      if (le32_to_cpu(rec->e_cpos) == cpos && rec_range == trunc_range) {
            int next_free;

            memset(rec, 0, sizeof(*rec));
            ocfs2_cleanup_merge(el, index);
            wants_rotate = 1;

            next_free = le16_to_cpu(el->l_next_free_rec);
            if (is_rightmost_tree_rec && next_free > 1) {
                  /*
                   * We skip the edge update if this path will
                   * be deleted by the rotate code.
                   */
                  rec = &el->l_recs[next_free - 1];
                  ocfs2_adjust_rightmost_records(inode, handle, path,
                                           rec);
            }
      } else if (le32_to_cpu(rec->e_cpos) == cpos) {
            /* Remove leftmost portion of the record. */
            le32_add_cpu(&rec->e_cpos, len);
            le64_add_cpu(&rec->e_blkno, ocfs2_clusters_to_blocks(sb, len));
            le16_add_cpu(&rec->e_leaf_clusters, -len);
      } else if (rec_range == trunc_range) {
            /* Remove rightmost portion of the record */
            le16_add_cpu(&rec->e_leaf_clusters, -len);
            if (is_rightmost_tree_rec)
                  ocfs2_adjust_rightmost_records(inode, handle, path, rec);
      } else {
            /* Caller should have trapped this. */
            mlog(ML_ERROR, "Inode %llu: Invalid record truncate: (%u, %u) "
                 "(%u, %u)\n", (unsigned long long)OCFS2_I(inode)->ip_blkno,
                 le32_to_cpu(rec->e_cpos),
                 le16_to_cpu(rec->e_leaf_clusters), cpos, len);
            BUG();
      }

      if (left_path) {
            int subtree_index;

            subtree_index = ocfs2_find_subtree_root(inode, left_path, path);
            ocfs2_complete_edge_insert(inode, handle, left_path, path,
                                 subtree_index);
      }

      ocfs2_journal_dirty(handle, path_leaf_bh(path));

      ret = ocfs2_rotate_tree_left(inode, handle, path, dealloc, et);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

out:
      ocfs2_free_path(left_path);
      return ret;
}

int ocfs2_remove_extent(struct inode *inode,
                  struct ocfs2_extent_tree *et,
                  u32 cpos, u32 len, handle_t *handle,
                  struct ocfs2_alloc_context *meta_ac,
                  struct ocfs2_cached_dealloc_ctxt *dealloc)
{
      int ret, index;
      u32 rec_range, trunc_range;
      struct ocfs2_extent_rec *rec;
      struct ocfs2_extent_list *el;
      struct ocfs2_path *path = NULL;

      ocfs2_extent_map_trunc(inode, 0);

      path = ocfs2_new_path_from_et(et);
      if (!path) {
            ret = -ENOMEM;
            mlog_errno(ret);
            goto out;
      }

      ret = ocfs2_find_path(inode, path, cpos);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      el = path_leaf_el(path);
      index = ocfs2_search_extent_list(el, cpos);
      if (index == -1 || index >= le16_to_cpu(el->l_next_free_rec)) {
            ocfs2_error(inode->i_sb,
                      "Inode %llu has an extent at cpos %u which can no "
                      "longer be found.\n",
                      (unsigned long long)OCFS2_I(inode)->ip_blkno, cpos);
            ret = -EROFS;
            goto out;
      }

      /*
       * We have 3 cases of extent removal:
       *   1) Range covers the entire extent rec
       *   2) Range begins or ends on one edge of the extent rec
       *   3) Range is in the middle of the extent rec (no shared edges)
       *
       * For case 1 we remove the extent rec and left rotate to
       * fill the hole.
       *
       * For case 2 we just shrink the existing extent rec, with a
       * tree update if the shrinking edge is also the edge of an
       * extent block.
       *
       * For case 3 we do a right split to turn the extent rec into
       * something case 2 can handle.
       */
      rec = &el->l_recs[index];
      rec_range = le32_to_cpu(rec->e_cpos) + ocfs2_rec_clusters(el, rec);
      trunc_range = cpos + len;

      BUG_ON(cpos < le32_to_cpu(rec->e_cpos) || trunc_range > rec_range);

      mlog(0, "Inode %llu, remove (cpos %u, len %u). Existing index %d "
           "(cpos %u, len %u)\n",
           (unsigned long long)OCFS2_I(inode)->ip_blkno, cpos, len, index,
           le32_to_cpu(rec->e_cpos), ocfs2_rec_clusters(el, rec));

      if (le32_to_cpu(rec->e_cpos) == cpos || rec_range == trunc_range) {
            ret = ocfs2_truncate_rec(inode, handle, path, index, dealloc,
                               cpos, len, et);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }
      } else {
            ret = ocfs2_split_tree(inode, et, handle, path, index,
                               trunc_range, meta_ac);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            /*
             * The split could have manipulated the tree enough to
             * move the record location, so we have to look for it again.
             */
            ocfs2_reinit_path(path, 1);

            ret = ocfs2_find_path(inode, path, cpos);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            el = path_leaf_el(path);
            index = ocfs2_search_extent_list(el, cpos);
            if (index == -1 || index >= le16_to_cpu(el->l_next_free_rec)) {
                  ocfs2_error(inode->i_sb,
                            "Inode %llu: split at cpos %u lost record.",
                            (unsigned long long)OCFS2_I(inode)->ip_blkno,
                            cpos);
                  ret = -EROFS;
                  goto out;
            }

            /*
             * Double check our values here. If anything is fishy,
             * it's easier to catch it at the top level.
             */
            rec = &el->l_recs[index];
            rec_range = le32_to_cpu(rec->e_cpos) +
                  ocfs2_rec_clusters(el, rec);
            if (rec_range != trunc_range) {
                  ocfs2_error(inode->i_sb,
                            "Inode %llu: error after split at cpos %u"
                            "trunc len %u, existing record is (%u,%u)",
                            (unsigned long long)OCFS2_I(inode)->ip_blkno,
                            cpos, len, le32_to_cpu(rec->e_cpos),
                            ocfs2_rec_clusters(el, rec));
                  ret = -EROFS;
                  goto out;
            }

            ret = ocfs2_truncate_rec(inode, handle, path, index, dealloc,
                               cpos, len, et);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }
      }

out:
      ocfs2_free_path(path);
      return ret;
}

int ocfs2_remove_btree_range(struct inode *inode,
                       struct ocfs2_extent_tree *et,
                       u32 cpos, u32 phys_cpos, u32 len,
                       struct ocfs2_cached_dealloc_ctxt *dealloc)
{
      int ret;
      u64 phys_blkno = ocfs2_clusters_to_blocks(inode->i_sb, phys_cpos);
      struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
      struct inode *tl_inode = osb->osb_tl_inode;
      handle_t *handle;
      struct ocfs2_alloc_context *meta_ac = NULL;

      ret = ocfs2_lock_allocators(inode, et, 0, 1, NULL, &meta_ac);
      if (ret) {
            mlog_errno(ret);
            return ret;
      }

      mutex_lock(&tl_inode->i_mutex);

      if (ocfs2_truncate_log_needs_flush(osb)) {
            ret = __ocfs2_flush_truncate_log(osb);
            if (ret < 0) {
                  mlog_errno(ret);
                  goto out;
            }
      }

      handle = ocfs2_start_trans(osb, ocfs2_remove_extent_credits(osb->sb));
      if (IS_ERR(handle)) {
            ret = PTR_ERR(handle);
            mlog_errno(ret);
            goto out;
      }

      ret = ocfs2_et_root_journal_access(handle, inode, et,
                                 OCFS2_JOURNAL_ACCESS_WRITE);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      vfs_dq_free_space_nodirty(inode,
                          ocfs2_clusters_to_bytes(inode->i_sb, len));

      ret = ocfs2_remove_extent(inode, et, cpos, len, handle, meta_ac,
                          dealloc);
      if (ret) {
            mlog_errno(ret);
            goto out_commit;
      }

      ocfs2_et_update_clusters(inode, et, -len);

      ret = ocfs2_journal_dirty(handle, et->et_root_bh);
      if (ret) {
            mlog_errno(ret);
            goto out_commit;
      }

      ret = ocfs2_truncate_log_append(osb, handle, phys_blkno, len);
      if (ret)
            mlog_errno(ret);

out_commit:
      ocfs2_commit_trans(osb, handle);
out:
      mutex_unlock(&tl_inode->i_mutex);

      if (meta_ac)
            ocfs2_free_alloc_context(meta_ac);

      return ret;
}

int ocfs2_truncate_log_needs_flush(struct ocfs2_super *osb)
{
      struct buffer_head *tl_bh = osb->osb_tl_bh;
      struct ocfs2_dinode *di;
      struct ocfs2_truncate_log *tl;

      di = (struct ocfs2_dinode *) tl_bh->b_data;
      tl = &di->id2.i_dealloc;

      mlog_bug_on_msg(le16_to_cpu(tl->tl_used) > le16_to_cpu(tl->tl_count),
                  "slot %d, invalid truncate log parameters: used = "
                  "%u, count = %u\n", osb->slot_num,
                  le16_to_cpu(tl->tl_used), le16_to_cpu(tl->tl_count));
      return le16_to_cpu(tl->tl_used) == le16_to_cpu(tl->tl_count);
}

static int ocfs2_truncate_log_can_coalesce(struct ocfs2_truncate_log *tl,
                                 unsigned int new_start)
{
      unsigned int tail_index;
      unsigned int current_tail;

      /* No records, nothing to coalesce */
      if (!le16_to_cpu(tl->tl_used))
            return 0;

      tail_index = le16_to_cpu(tl->tl_used) - 1;
      current_tail = le32_to_cpu(tl->tl_recs[tail_index].t_start);
      current_tail += le32_to_cpu(tl->tl_recs[tail_index].t_clusters);

      return current_tail == new_start;
}

int ocfs2_truncate_log_append(struct ocfs2_super *osb,
                        handle_t *handle,
                        u64 start_blk,
                        unsigned int num_clusters)
{
      int status, index;
      unsigned int start_cluster, tl_count;
      struct inode *tl_inode = osb->osb_tl_inode;
      struct buffer_head *tl_bh = osb->osb_tl_bh;
      struct ocfs2_dinode *di;
      struct ocfs2_truncate_log *tl;

      mlog_entry("start_blk = %llu, num_clusters = %u\n",
               (unsigned long long)start_blk, num_clusters);

      BUG_ON(mutex_trylock(&tl_inode->i_mutex));

      start_cluster = ocfs2_blocks_to_clusters(osb->sb, start_blk);

      di = (struct ocfs2_dinode *) tl_bh->b_data;

      /* tl_bh is loaded from ocfs2_truncate_log_init().  It's validated
       * by the underlying call to ocfs2_read_inode_block(), so any
       * corruption is a code bug */
      BUG_ON(!OCFS2_IS_VALID_DINODE(di));

      tl = &di->id2.i_dealloc;
      tl_count = le16_to_cpu(tl->tl_count);
      mlog_bug_on_msg(tl_count > ocfs2_truncate_recs_per_inode(osb->sb) ||
                  tl_count == 0,
                  "Truncate record count on #%llu invalid "
                  "wanted %u, actual %u\n",
                  (unsigned long long)OCFS2_I(tl_inode)->ip_blkno,
                  ocfs2_truncate_recs_per_inode(osb->sb),
                  le16_to_cpu(tl->tl_count));

      /* Caller should have known to flush before calling us. */
      index = le16_to_cpu(tl->tl_used);
      if (index >= tl_count) {
            status = -ENOSPC;
            mlog_errno(status);
            goto bail;
      }

      status = ocfs2_journal_access_di(handle, tl_inode, tl_bh,
                               OCFS2_JOURNAL_ACCESS_WRITE);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

      mlog(0, "Log truncate of %u clusters starting at cluster %u to "
           "%llu (index = %d)\n", num_clusters, start_cluster,
           (unsigned long long)OCFS2_I(tl_inode)->ip_blkno, index);

      if (ocfs2_truncate_log_can_coalesce(tl, start_cluster)) {
            /*
             * Move index back to the record we are coalescing with.
             * ocfs2_truncate_log_can_coalesce() guarantees nonzero
             */
            index--;

            num_clusters += le32_to_cpu(tl->tl_recs[index].t_clusters);
            mlog(0, "Coalesce with index %u (start = %u, clusters = %u)\n",
                 index, le32_to_cpu(tl->tl_recs[index].t_start),
                 num_clusters);
      } else {
            tl->tl_recs[index].t_start = cpu_to_le32(start_cluster);
            tl->tl_used = cpu_to_le16(index + 1);
      }
      tl->tl_recs[index].t_clusters = cpu_to_le32(num_clusters);

      status = ocfs2_journal_dirty(handle, tl_bh);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

bail:
      mlog_exit(status);
      return status;
}

static int ocfs2_replay_truncate_records(struct ocfs2_super *osb,
                               handle_t *handle,
                               struct inode *data_alloc_inode,
                               struct buffer_head *data_alloc_bh)
{
      int status = 0;
      int i;
      unsigned int num_clusters;
      u64 start_blk;
      struct ocfs2_truncate_rec rec;
      struct ocfs2_dinode *di;
      struct ocfs2_truncate_log *tl;
      struct inode *tl_inode = osb->osb_tl_inode;
      struct buffer_head *tl_bh = osb->osb_tl_bh;

      mlog_entry_void();

      di = (struct ocfs2_dinode *) tl_bh->b_data;
      tl = &di->id2.i_dealloc;
      i = le16_to_cpu(tl->tl_used) - 1;
      while (i >= 0) {
            /* Caller has given us at least enough credits to
             * update the truncate log dinode */
            status = ocfs2_journal_access_di(handle, tl_inode, tl_bh,
                                     OCFS2_JOURNAL_ACCESS_WRITE);
            if (status < 0) {
                  mlog_errno(status);
                  goto bail;
            }

            tl->tl_used = cpu_to_le16(i);

            status = ocfs2_journal_dirty(handle, tl_bh);
            if (status < 0) {
                  mlog_errno(status);
                  goto bail;
            }

            /* TODO: Perhaps we can calculate the bulk of the
             * credits up front rather than extending like
             * this. */
            status = ocfs2_extend_trans(handle,
                                  OCFS2_TRUNCATE_LOG_FLUSH_ONE_REC);
            if (status < 0) {
                  mlog_errno(status);
                  goto bail;
            }

            rec = tl->tl_recs[i];
            start_blk = ocfs2_clusters_to_blocks(data_alloc_inode->i_sb,
                                        le32_to_cpu(rec.t_start));
            num_clusters = le32_to_cpu(rec.t_clusters);

            /* if start_blk is not set, we ignore the record as
             * invalid. */
            if (start_blk) {
                  mlog(0, "free record %d, start = %u, clusters = %u\n",
                       i, le32_to_cpu(rec.t_start), num_clusters);

                  status = ocfs2_free_clusters(handle, data_alloc_inode,
                                         data_alloc_bh, start_blk,
                                         num_clusters);
                  if (status < 0) {
                        mlog_errno(status);
                        goto bail;
                  }
            }
            i--;
      }

bail:
      mlog_exit(status);
      return status;
}

/* Expects you to already be holding tl_inode->i_mutex */
int __ocfs2_flush_truncate_log(struct ocfs2_super *osb)
{
      int status;
      unsigned int num_to_flush;
      handle_t *handle;
      struct inode *tl_inode = osb->osb_tl_inode;
      struct inode *data_alloc_inode = NULL;
      struct buffer_head *tl_bh = osb->osb_tl_bh;
      struct buffer_head *data_alloc_bh = NULL;
      struct ocfs2_dinode *di;
      struct ocfs2_truncate_log *tl;

      mlog_entry_void();

      BUG_ON(mutex_trylock(&tl_inode->i_mutex));

      di = (struct ocfs2_dinode *) tl_bh->b_data;

      /* tl_bh is loaded from ocfs2_truncate_log_init().  It's validated
       * by the underlying call to ocfs2_read_inode_block(), so any
       * corruption is a code bug */
      BUG_ON(!OCFS2_IS_VALID_DINODE(di));

      tl = &di->id2.i_dealloc;
      num_to_flush = le16_to_cpu(tl->tl_used);
      mlog(0, "Flush %u records from truncate log #%llu\n",
           num_to_flush, (unsigned long long)OCFS2_I(tl_inode)->ip_blkno);
      if (!num_to_flush) {
            status = 0;
            goto out;
      }

      data_alloc_inode = ocfs2_get_system_file_inode(osb,
                                           GLOBAL_BITMAP_SYSTEM_INODE,
                                           OCFS2_INVALID_SLOT);
      if (!data_alloc_inode) {
            status = -EINVAL;
            mlog(ML_ERROR, "Could not get bitmap inode!\n");
            goto out;
      }

      mutex_lock(&data_alloc_inode->i_mutex);

      status = ocfs2_inode_lock(data_alloc_inode, &data_alloc_bh, 1);
      if (status < 0) {
            mlog_errno(status);
            goto out_mutex;
      }

      handle = ocfs2_start_trans(osb, OCFS2_TRUNCATE_LOG_UPDATE);
      if (IS_ERR(handle)) {
            status = PTR_ERR(handle);
            mlog_errno(status);
            goto out_unlock;
      }

      status = ocfs2_replay_truncate_records(osb, handle, data_alloc_inode,
                                     data_alloc_bh);
      if (status < 0)
            mlog_errno(status);

      ocfs2_commit_trans(osb, handle);

out_unlock:
      brelse(data_alloc_bh);
      ocfs2_inode_unlock(data_alloc_inode, 1);

out_mutex:
      mutex_unlock(&data_alloc_inode->i_mutex);
      iput(data_alloc_inode);

out:
      mlog_exit(status);
      return status;
}

int ocfs2_flush_truncate_log(struct ocfs2_super *osb)
{
      int status;
      struct inode *tl_inode = osb->osb_tl_inode;

      mutex_lock(&tl_inode->i_mutex);
      status = __ocfs2_flush_truncate_log(osb);
      mutex_unlock(&tl_inode->i_mutex);

      return status;
}

static void ocfs2_truncate_log_worker(struct work_struct *work)
{
      int status;
      struct ocfs2_super *osb =
            container_of(work, struct ocfs2_super,
                       osb_truncate_log_wq.work);

      mlog_entry_void();

      status = ocfs2_flush_truncate_log(osb);
      if (status < 0)
            mlog_errno(status);
      else
            ocfs2_init_inode_steal_slot(osb);

      mlog_exit(status);
}

#define OCFS2_TRUNCATE_LOG_FLUSH_INTERVAL (2 * HZ)
void ocfs2_schedule_truncate_log_flush(struct ocfs2_super *osb,
                               int cancel)
{
      if (osb->osb_tl_inode) {
            /* We want to push off log flushes while truncates are
             * still running. */
            if (cancel)
                  cancel_delayed_work(&osb->osb_truncate_log_wq);

            queue_delayed_work(ocfs2_wq, &osb->osb_truncate_log_wq,
                           OCFS2_TRUNCATE_LOG_FLUSH_INTERVAL);
      }
}

static int ocfs2_get_truncate_log_info(struct ocfs2_super *osb,
                               int slot_num,
                               struct inode **tl_inode,
                               struct buffer_head **tl_bh)
{
      int status;
      struct inode *inode = NULL;
      struct buffer_head *bh = NULL;

      inode = ocfs2_get_system_file_inode(osb,
                                 TRUNCATE_LOG_SYSTEM_INODE,
                                 slot_num);
      if (!inode) {
            status = -EINVAL;
            mlog(ML_ERROR, "Could not get load truncate log inode!\n");
            goto bail;
      }

      status = ocfs2_read_inode_block(inode, &bh);
      if (status < 0) {
            iput(inode);
            mlog_errno(status);
            goto bail;
      }

      *tl_inode = inode;
      *tl_bh    = bh;
bail:
      mlog_exit(status);
      return status;
}

/* called during the 1st stage of node recovery. we stamp a clean
 * truncate log and pass back a copy for processing later. if the
 * truncate log does not require processing, a *tl_copy is set to
 * NULL. */
int ocfs2_begin_truncate_log_recovery(struct ocfs2_super *osb,
                              int slot_num,
                              struct ocfs2_dinode **tl_copy)
{
      int status;
      struct inode *tl_inode = NULL;
      struct buffer_head *tl_bh = NULL;
      struct ocfs2_dinode *di;
      struct ocfs2_truncate_log *tl;

      *tl_copy = NULL;

      mlog(0, "recover truncate log from slot %d\n", slot_num);

      status = ocfs2_get_truncate_log_info(osb, slot_num, &tl_inode, &tl_bh);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

      di = (struct ocfs2_dinode *) tl_bh->b_data;

      /* tl_bh is loaded from ocfs2_get_truncate_log_info().  It's
       * validated by the underlying call to ocfs2_read_inode_block(),
       * so any corruption is a code bug */
      BUG_ON(!OCFS2_IS_VALID_DINODE(di));

      tl = &di->id2.i_dealloc;
      if (le16_to_cpu(tl->tl_used)) {
            mlog(0, "We'll have %u logs to recover\n",
                 le16_to_cpu(tl->tl_used));

            *tl_copy = kmalloc(tl_bh->b_size, GFP_KERNEL);
            if (!(*tl_copy)) {
                  status = -ENOMEM;
                  mlog_errno(status);
                  goto bail;
            }

            /* Assuming the write-out below goes well, this copy
             * will be passed back to recovery for processing. */
            memcpy(*tl_copy, tl_bh->b_data, tl_bh->b_size);

            /* All we need to do to clear the truncate log is set
             * tl_used. */
            tl->tl_used = 0;

            ocfs2_compute_meta_ecc(osb->sb, tl_bh->b_data, &di->i_check);
            status = ocfs2_write_block(osb, tl_bh, tl_inode);
            if (status < 0) {
                  mlog_errno(status);
                  goto bail;
            }
      }

bail:
      if (tl_inode)
            iput(tl_inode);
      brelse(tl_bh);

      if (status < 0 && (*tl_copy)) {
            kfree(*tl_copy);
            *tl_copy = NULL;
      }

      mlog_exit(status);
      return status;
}

int ocfs2_complete_truncate_log_recovery(struct ocfs2_super *osb,
                               struct ocfs2_dinode *tl_copy)
{
      int status = 0;
      int i;
      unsigned int clusters, num_recs, start_cluster;
      u64 start_blk;
      handle_t *handle;
      struct inode *tl_inode = osb->osb_tl_inode;
      struct ocfs2_truncate_log *tl;

      mlog_entry_void();

      if (OCFS2_I(tl_inode)->ip_blkno == le64_to_cpu(tl_copy->i_blkno)) {
            mlog(ML_ERROR, "Asked to recover my own truncate log!\n");
            return -EINVAL;
      }

      tl = &tl_copy->id2.i_dealloc;
      num_recs = le16_to_cpu(tl->tl_used);
      mlog(0, "cleanup %u records from %llu\n", num_recs,
           (unsigned long long)le64_to_cpu(tl_copy->i_blkno));

      mutex_lock(&tl_inode->i_mutex);
      for(i = 0; i < num_recs; i++) {
            if (ocfs2_truncate_log_needs_flush(osb)) {
                  status = __ocfs2_flush_truncate_log(osb);
                  if (status < 0) {
                        mlog_errno(status);
                        goto bail_up;
                  }
            }

            handle = ocfs2_start_trans(osb, OCFS2_TRUNCATE_LOG_UPDATE);
            if (IS_ERR(handle)) {
                  status = PTR_ERR(handle);
                  mlog_errno(status);
                  goto bail_up;
            }

            clusters = le32_to_cpu(tl->tl_recs[i].t_clusters);
            start_cluster = le32_to_cpu(tl->tl_recs[i].t_start);
            start_blk = ocfs2_clusters_to_blocks(osb->sb, start_cluster);

            status = ocfs2_truncate_log_append(osb, handle,
                                       start_blk, clusters);
            ocfs2_commit_trans(osb, handle);
            if (status < 0) {
                  mlog_errno(status);
                  goto bail_up;
            }
      }

bail_up:
      mutex_unlock(&tl_inode->i_mutex);

      mlog_exit(status);
      return status;
}

void ocfs2_truncate_log_shutdown(struct ocfs2_super *osb)
{
      int status;
      struct inode *tl_inode = osb->osb_tl_inode;

      mlog_entry_void();

      if (tl_inode) {
            cancel_delayed_work(&osb->osb_truncate_log_wq);
            flush_workqueue(ocfs2_wq);

            status = ocfs2_flush_truncate_log(osb);
            if (status < 0)
                  mlog_errno(status);

            brelse(osb->osb_tl_bh);
            iput(osb->osb_tl_inode);
      }

      mlog_exit_void();
}

int ocfs2_truncate_log_init(struct ocfs2_super *osb)
{
      int status;
      struct inode *tl_inode = NULL;
      struct buffer_head *tl_bh = NULL;

      mlog_entry_void();

      status = ocfs2_get_truncate_log_info(osb,
                                   osb->slot_num,
                                   &tl_inode,
                                   &tl_bh);
      if (status < 0)
            mlog_errno(status);

      /* ocfs2_truncate_log_shutdown keys on the existence of
       * osb->osb_tl_inode so we don't set any of the osb variables
       * until we're sure all is well. */
      INIT_DELAYED_WORK(&osb->osb_truncate_log_wq,
                    ocfs2_truncate_log_worker);
      osb->osb_tl_bh    = tl_bh;
      osb->osb_tl_inode = tl_inode;

      mlog_exit(status);
      return status;
}

/*
 * Delayed de-allocation of suballocator blocks.
 *
 * Some sets of block de-allocations might involve multiple suballocator inodes.
 *
 * The locking for this can get extremely complicated, especially when
 * the suballocator inodes to delete from aren't known until deep
 * within an unrelated codepath.
 *
 * ocfs2_extent_block structures are a good example of this - an inode
 * btree could have been grown by any number of nodes each allocating
 * out of their own suballoc inode.
 *
 * These structures allow the delay of block de-allocation until a
 * later time, when locking of multiple cluster inodes won't cause
 * deadlock.
 */

/*
 * Describe a single bit freed from a suballocator.  For the block
 * suballocators, it represents one block.  For the global cluster
 * allocator, it represents some clusters and free_bit indicates
 * clusters number.
 */
06167 struct ocfs2_cached_block_free {
      struct ocfs2_cached_block_free            *free_next;
      u64                           free_blk;
      unsigned int                        free_bit;
};

06173 struct ocfs2_per_slot_free_list {
      struct ocfs2_per_slot_free_list           *f_next_suballocator;
      int                           f_inode_type;
      int                           f_slot;
      struct ocfs2_cached_block_free            *f_first;
};

static int ocfs2_free_cached_blocks(struct ocfs2_super *osb,
                            int sysfile_type,
                            int slot,
                            struct ocfs2_cached_block_free *head)
{
      int ret;
      u64 bg_blkno;
      handle_t *handle;
      struct inode *inode;
      struct buffer_head *di_bh = NULL;
      struct ocfs2_cached_block_free *tmp;

      inode = ocfs2_get_system_file_inode(osb, sysfile_type, slot);
      if (!inode) {
            ret = -EINVAL;
            mlog_errno(ret);
            goto out;
      }

      mutex_lock(&inode->i_mutex);

      ret = ocfs2_inode_lock(inode, &di_bh, 1);
      if (ret) {
            mlog_errno(ret);
            goto out_mutex;
      }

      handle = ocfs2_start_trans(osb, OCFS2_SUBALLOC_FREE);
      if (IS_ERR(handle)) {
            ret = PTR_ERR(handle);
            mlog_errno(ret);
            goto out_unlock;
      }

      while (head) {
            bg_blkno = ocfs2_which_suballoc_group(head->free_blk,
                                          head->free_bit);
            mlog(0, "Free bit: (bit %u, blkno %llu)\n",
                 head->free_bit, (unsigned long long)head->free_blk);

            ret = ocfs2_free_suballoc_bits(handle, inode, di_bh,
                                     head->free_bit, bg_blkno, 1);
            if (ret) {
                  mlog_errno(ret);
                  goto out_journal;
            }

            ret = ocfs2_extend_trans(handle, OCFS2_SUBALLOC_FREE);
            if (ret) {
                  mlog_errno(ret);
                  goto out_journal;
            }

            tmp = head;
            head = head->free_next;
            kfree(tmp);
      }

out_journal:
      ocfs2_commit_trans(osb, handle);

out_unlock:
      ocfs2_inode_unlock(inode, 1);
      brelse(di_bh);
out_mutex:
      mutex_unlock(&inode->i_mutex);
      iput(inode);
out:
      while(head) {
            /* Premature exit may have left some dangling items. */
            tmp = head;
            head = head->free_next;
            kfree(tmp);
      }

      return ret;
}

int ocfs2_cache_cluster_dealloc(struct ocfs2_cached_dealloc_ctxt *ctxt,
                        u64 blkno, unsigned int bit)
{
      int ret = 0;
      struct ocfs2_cached_block_free *item;

      item = kmalloc(sizeof(*item), GFP_NOFS);
      if (item == NULL) {
            ret = -ENOMEM;
            mlog_errno(ret);
            return ret;
      }

      mlog(0, "Insert clusters: (bit %u, blk %llu)\n",
           bit, (unsigned long long)blkno);

      item->free_blk = blkno;
      item->free_bit = bit;
      item->free_next = ctxt->c_global_allocator;

      ctxt->c_global_allocator = item;
      return ret;
}

static int ocfs2_free_cached_clusters(struct ocfs2_super *osb,
                              struct ocfs2_cached_block_free *head)
{
      struct ocfs2_cached_block_free *tmp;
      struct inode *tl_inode = osb->osb_tl_inode;
      handle_t *handle;
      int ret = 0;

      mutex_lock(&tl_inode->i_mutex);

      while (head) {
            if (ocfs2_truncate_log_needs_flush(osb)) {
                  ret = __ocfs2_flush_truncate_log(osb);
                  if (ret < 0) {
                        mlog_errno(ret);
                        break;
                  }
            }

            handle = ocfs2_start_trans(osb, OCFS2_TRUNCATE_LOG_UPDATE);
            if (IS_ERR(handle)) {
                  ret = PTR_ERR(handle);
                  mlog_errno(ret);
                  break;
            }

            ret = ocfs2_truncate_log_append(osb, handle, head->free_blk,
                                    head->free_bit);

            ocfs2_commit_trans(osb, handle);
            tmp = head;
            head = head->free_next;
            kfree(tmp);

            if (ret < 0) {
                  mlog_errno(ret);
                  break;
            }
      }

      mutex_unlock(&tl_inode->i_mutex);

      while (head) {
            /* Premature exit may have left some dangling items. */
            tmp = head;
            head = head->free_next;
            kfree(tmp);
      }

      return ret;
}

int ocfs2_run_deallocs(struct ocfs2_super *osb,
                   struct ocfs2_cached_dealloc_ctxt *ctxt)
{
      int ret = 0, ret2;
      struct ocfs2_per_slot_free_list *fl;

      if (!ctxt)
            return 0;

      while (ctxt->c_first_suballocator) {
            fl = ctxt->c_first_suballocator;

            if (fl->f_first) {
                  mlog(0, "Free items: (type %u, slot %d)\n",
                       fl->f_inode_type, fl->f_slot);
                  ret2 = ocfs2_free_cached_blocks(osb,
                                          fl->f_inode_type,
                                          fl->f_slot,
                                          fl->f_first);
                  if (ret2)
                        mlog_errno(ret2);
                  if (!ret)
                        ret = ret2;
            }

            ctxt->c_first_suballocator = fl->f_next_suballocator;
            kfree(fl);
      }

      if (ctxt->c_global_allocator) {
            ret2 = ocfs2_free_cached_clusters(osb,
                                      ctxt->c_global_allocator);
            if (ret2)
                  mlog_errno(ret2);
            if (!ret)
                  ret = ret2;

            ctxt->c_global_allocator = NULL;
      }

      return ret;
}

static struct ocfs2_per_slot_free_list *
ocfs2_find_per_slot_free_list(int type,
                        int slot,
                        struct ocfs2_cached_dealloc_ctxt *ctxt)
{
      struct ocfs2_per_slot_free_list *fl = ctxt->c_first_suballocator;

      while (fl) {
            if (fl->f_inode_type == type && fl->f_slot == slot)
                  return fl;

            fl = fl->f_next_suballocator;
      }

      fl = kmalloc(sizeof(*fl), GFP_NOFS);
      if (fl) {
            fl->f_inode_type = type;
            fl->f_slot = slot;
            fl->f_first = NULL;
            fl->f_next_suballocator = ctxt->c_first_suballocator;

            ctxt->c_first_suballocator = fl;
      }
      return fl;
}

static int ocfs2_cache_block_dealloc(struct ocfs2_cached_dealloc_ctxt *ctxt,
                             int type, int slot, u64 blkno,
                             unsigned int bit)
{
      int ret;
      struct ocfs2_per_slot_free_list *fl;
      struct ocfs2_cached_block_free *item;

      fl = ocfs2_find_per_slot_free_list(type, slot, ctxt);
      if (fl == NULL) {
            ret = -ENOMEM;
            mlog_errno(ret);
            goto out;
      }

      item = kmalloc(sizeof(*item), GFP_NOFS);
      if (item == NULL) {
            ret = -ENOMEM;
            mlog_errno(ret);
            goto out;
      }

      mlog(0, "Insert: (type %d, slot %u, bit %u, blk %llu)\n",
           type, slot, bit, (unsigned long long)blkno);

      item->free_blk = blkno;
      item->free_bit = bit;
      item->free_next = fl->f_first;

      fl->f_first = item;

      ret = 0;
out:
      return ret;
}

static int ocfs2_cache_extent_block_free(struct ocfs2_cached_dealloc_ctxt *ctxt,
                               struct ocfs2_extent_block *eb)
{
      return ocfs2_cache_block_dealloc(ctxt, EXTENT_ALLOC_SYSTEM_INODE,
                               le16_to_cpu(eb->h_suballoc_slot),
                               le64_to_cpu(eb->h_blkno),
                               le16_to_cpu(eb->h_suballoc_bit));
}

/* This function will figure out whether the currently last extent
 * block will be deleted, and if it will, what the new last extent
 * block will be so we can update his h_next_leaf_blk field, as well
 * as the dinodes i_last_eb_blk */
static int ocfs2_find_new_last_ext_blk(struct inode *inode,
                               unsigned int clusters_to_del,
                               struct ocfs2_path *path,
                               struct buffer_head **new_last_eb)
{
      int next_free, ret = 0;
      u32 cpos;
      struct ocfs2_extent_rec *rec;
      struct ocfs2_extent_block *eb;
      struct ocfs2_extent_list *el;
      struct buffer_head *bh = NULL;

      *new_last_eb = NULL;

      /* we have no tree, so of course, no last_eb. */
      if (!path->p_tree_depth)
            goto out;

      /* trunc to zero special case - this makes tree_depth = 0
       * regardless of what it is.  */
      if (OCFS2_I(inode)->ip_clusters == clusters_to_del)
            goto out;

      el = path_leaf_el(path);
      BUG_ON(!el->l_next_free_rec);

      /*
       * Make sure that this extent list will actually be empty
       * after we clear away the data. We can shortcut out if
       * there's more than one non-empty extent in the
       * list. Otherwise, a check of the remaining extent is
       * necessary.
       */
      next_free = le16_to_cpu(el->l_next_free_rec);
      rec = NULL;
      if (ocfs2_is_empty_extent(&el->l_recs[0])) {
            if (next_free > 2)
                  goto out;

            /* We may have a valid extent in index 1, check it. */
            if (next_free == 2)
                  rec = &el->l_recs[1];

            /*
             * Fall through - no more nonempty extents, so we want
             * to delete this leaf.
             */
      } else {
            if (next_free > 1)
                  goto out;

            rec = &el->l_recs[0];
      }

      if (rec) {
            /*
             * Check it we'll only be trimming off the end of this
             * cluster.
             */
            if (le16_to_cpu(rec->e_leaf_clusters) > clusters_to_del)
                  goto out;
      }

      ret = ocfs2_find_cpos_for_left_leaf(inode->i_sb, path, &cpos);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      ret = ocfs2_find_leaf(inode, path_root_el(path), cpos, &bh);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      eb = (struct ocfs2_extent_block *) bh->b_data;
      el = &eb->h_list;

      /* ocfs2_find_leaf() gets the eb from ocfs2_read_extent_block().
       * Any corruption is a code bug. */
      BUG_ON(!OCFS2_IS_VALID_EXTENT_BLOCK(eb));

      *new_last_eb = bh;
      get_bh(*new_last_eb);
      mlog(0, "returning block %llu, (cpos: %u)\n",
           (unsigned long long)le64_to_cpu(eb->h_blkno), cpos);
out:
      brelse(bh);

      return ret;
}

/*
 * Trim some clusters off the rightmost edge of a tree. Only called
 * during truncate.
 *
 * The caller needs to:
 *   - start journaling of each path component.
 *   - compute and fully set up any new last ext block
 */
static int ocfs2_trim_tree(struct inode *inode, struct ocfs2_path *path,
                     handle_t *handle, struct ocfs2_truncate_context *tc,
                     u32 clusters_to_del, u64 *delete_start)
{
      int ret, i, index = path->p_tree_depth;
      u32 new_edge = 0;
      u64 deleted_eb = 0;
      struct buffer_head *bh;
      struct ocfs2_extent_list *el;
      struct ocfs2_extent_rec *rec;

      *delete_start = 0;

      while (index >= 0) {
            bh = path->p_node[index].bh;
            el = path->p_node[index].el;

            mlog(0, "traveling tree (index = %d, block = %llu)\n",
                 index,  (unsigned long long)bh->b_blocknr);

            BUG_ON(le16_to_cpu(el->l_next_free_rec) == 0);

            if (index !=
                (path->p_tree_depth - le16_to_cpu(el->l_tree_depth))) {
                  ocfs2_error(inode->i_sb,
                            "Inode %lu has invalid ext. block %llu",
                            inode->i_ino,
                            (unsigned long long)bh->b_blocknr);
                  ret = -EROFS;
                  goto out;
            }

find_tail_record:
            i = le16_to_cpu(el->l_next_free_rec) - 1;
            rec = &el->l_recs[i];

            mlog(0, "Extent list before: record %d: (%u, %u, %llu), "
                 "next = %u\n", i, le32_to_cpu(rec->e_cpos),
                 ocfs2_rec_clusters(el, rec),
                 (unsigned long long)le64_to_cpu(rec->e_blkno),
                 le16_to_cpu(el->l_next_free_rec));

            BUG_ON(ocfs2_rec_clusters(el, rec) < clusters_to_del);

            if (le16_to_cpu(el->l_tree_depth) == 0) {
                  /*
                   * If the leaf block contains a single empty
                   * extent and no records, we can just remove
                   * the block.
                   */
                  if (i == 0 && ocfs2_is_empty_extent(rec)) {
                        memset(rec, 0,
                               sizeof(struct ocfs2_extent_rec));
                        el->l_next_free_rec = cpu_to_le16(0);

                        goto delete;
                  }

                  /*
                   * Remove any empty extents by shifting things
                   * left. That should make life much easier on
                   * the code below. This condition is rare
                   * enough that we shouldn't see a performance
                   * hit.
                   */
                  if (ocfs2_is_empty_extent(&el->l_recs[0])) {
                        le16_add_cpu(&el->l_next_free_rec, -1);

                        for(i = 0;
                            i < le16_to_cpu(el->l_next_free_rec); i++)
                              el->l_recs[i] = el->l_recs[i + 1];

                        memset(&el->l_recs[i], 0,
                               sizeof(struct ocfs2_extent_rec));

                        /*
                         * We've modified our extent list. The
                         * simplest way to handle this change
                         * is to being the search from the
                         * start again.
                         */
                        goto find_tail_record;
                  }

                  le16_add_cpu(&rec->e_leaf_clusters, -clusters_to_del);

                  /*
                   * We'll use "new_edge" on our way back up the
                   * tree to know what our rightmost cpos is.
                   */
                  new_edge = le16_to_cpu(rec->e_leaf_clusters);
                  new_edge += le32_to_cpu(rec->e_cpos);

                  /*
                   * The caller will use this to delete data blocks.
                   */
                  *delete_start = le64_to_cpu(rec->e_blkno)
                        + ocfs2_clusters_to_blocks(inode->i_sb,
                              le16_to_cpu(rec->e_leaf_clusters));

                  /*
                   * If it's now empty, remove this record.
                   */
                  if (le16_to_cpu(rec->e_leaf_clusters) == 0) {
                        memset(rec, 0,
                               sizeof(struct ocfs2_extent_rec));
                        le16_add_cpu(&el->l_next_free_rec, -1);
                  }
            } else {
                  if (le64_to_cpu(rec->e_blkno) == deleted_eb) {
                        memset(rec, 0,
                               sizeof(struct ocfs2_extent_rec));
                        le16_add_cpu(&el->l_next_free_rec, -1);

                        goto delete;
                  }

                  /* Can this actually happen? */
                  if (le16_to_cpu(el->l_next_free_rec) == 0)
                        goto delete;

                  /*
                   * We never actually deleted any clusters
                   * because our leaf was empty. There's no
                   * reason to adjust the rightmost edge then.
                   */
                  if (new_edge == 0)
                        goto delete;

                  rec->e_int_clusters = cpu_to_le32(new_edge);
                  le32_add_cpu(&rec->e_int_clusters,
                             -le32_to_cpu(rec->e_cpos));

                   /*
                    * A deleted child record should have been
                    * caught above.
                    */
                   BUG_ON(le32_to_cpu(rec->e_int_clusters) == 0);
            }

delete:
            ret = ocfs2_journal_dirty(handle, bh);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }

            mlog(0, "extent list container %llu, after: record %d: "
                 "(%u, %u, %llu), next = %u.\n",
                 (unsigned long long)bh->b_blocknr, i,
                 le32_to_cpu(rec->e_cpos), ocfs2_rec_clusters(el, rec),
                 (unsigned long long)le64_to_cpu(rec->e_blkno),
                 le16_to_cpu(el->l_next_free_rec));

            /*
             * We must be careful to only attempt delete of an
             * extent block (and not the root inode block).
             */
            if (index > 0 && le16_to_cpu(el->l_next_free_rec) == 0) {
                  struct ocfs2_extent_block *eb =
                        (struct ocfs2_extent_block *)bh->b_data;

                  /*
                   * Save this for use when processing the
                   * parent block.
                   */
                  deleted_eb = le64_to_cpu(eb->h_blkno);

                  mlog(0, "deleting this extent block.\n");

                  ocfs2_remove_from_cache(inode, bh);

                  BUG_ON(ocfs2_rec_clusters(el, &el->l_recs[0]));
                  BUG_ON(le32_to_cpu(el->l_recs[0].e_cpos));
                  BUG_ON(le64_to_cpu(el->l_recs[0].e_blkno));

                  ret = ocfs2_cache_extent_block_free(&tc->tc_dealloc, eb);
                  /* An error here is not fatal. */
                  if (ret < 0)
                        mlog_errno(ret);
            } else {
                  deleted_eb = 0;
            }

            index--;
      }

      ret = 0;
out:
      return ret;
}

static int ocfs2_do_truncate(struct ocfs2_super *osb,
                       unsigned int clusters_to_del,
                       struct inode *inode,
                       struct buffer_head *fe_bh,
                       handle_t *handle,
                       struct ocfs2_truncate_context *tc,
                       struct ocfs2_path *path)
{
      int status;
      struct ocfs2_dinode *fe;
      struct ocfs2_extent_block *last_eb = NULL;
      struct ocfs2_extent_list *el;
      struct buffer_head *last_eb_bh = NULL;
      u64 delete_blk = 0;

      fe = (struct ocfs2_dinode *) fe_bh->b_data;

      status = ocfs2_find_new_last_ext_blk(inode, clusters_to_del,
                                   path, &last_eb_bh);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

      /*
       * Each component will be touched, so we might as well journal
       * here to avoid having to handle errors later.
       */
      status = ocfs2_journal_access_path(inode, handle, path);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

      if (last_eb_bh) {
            status = ocfs2_journal_access_eb(handle, inode, last_eb_bh,
                                     OCFS2_JOURNAL_ACCESS_WRITE);
            if (status < 0) {
                  mlog_errno(status);
                  goto bail;
            }

            last_eb = (struct ocfs2_extent_block *) last_eb_bh->b_data;
      }

      el = &(fe->id2.i_list);

      /*
       * Lower levels depend on this never happening, but it's best
       * to check it up here before changing the tree.
       */
      if (el->l_tree_depth && el->l_recs[0].e_int_clusters == 0) {
            ocfs2_error(inode->i_sb,
                      "Inode %lu has an empty extent record, depth %u\n",
                      inode->i_ino, le16_to_cpu(el->l_tree_depth));
            status = -EROFS;
            goto bail;
      }

      vfs_dq_free_space_nodirty(inode,
                  ocfs2_clusters_to_bytes(osb->sb, clusters_to_del));
      spin_lock(&OCFS2_I(inode)->ip_lock);
      OCFS2_I(inode)->ip_clusters = le32_to_cpu(fe->i_clusters) -
                              clusters_to_del;
      spin_unlock(&OCFS2_I(inode)->ip_lock);
      le32_add_cpu(&fe->i_clusters, -clusters_to_del);
      inode->i_blocks = ocfs2_inode_sector_count(inode);

      status = ocfs2_trim_tree(inode, path, handle, tc,
                         clusters_to_del, &delete_blk);
      if (status) {
            mlog_errno(status);
            goto bail;
      }

      if (le32_to_cpu(fe->i_clusters) == 0) {
            /* trunc to zero is a special case. */
            el->l_tree_depth = 0;
            fe->i_last_eb_blk = 0;
      } else if (last_eb)
            fe->i_last_eb_blk = last_eb->h_blkno;

      status = ocfs2_journal_dirty(handle, fe_bh);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

      if (last_eb) {
            /* If there will be a new last extent block, then by
             * definition, there cannot be any leaves to the right of
             * him. */
            last_eb->h_next_leaf_blk = 0;
            status = ocfs2_journal_dirty(handle, last_eb_bh);
            if (status < 0) {
                  mlog_errno(status);
                  goto bail;
            }
      }

      if (delete_blk) {
            status = ocfs2_truncate_log_append(osb, handle, delete_blk,
                                       clusters_to_del);
            if (status < 0) {
                  mlog_errno(status);
                  goto bail;
            }
      }
      status = 0;
bail:
      brelse(last_eb_bh);
      mlog_exit(status);
      return status;
}

static int ocfs2_zero_func(handle_t *handle, struct buffer_head *bh)
{
      set_buffer_uptodate(bh);
      mark_buffer_dirty(bh);
      return 0;
}

static void ocfs2_map_and_dirty_page(struct inode *inode, handle_t *handle,
                             unsigned int from, unsigned int to,
                             struct page *page, int zero, u64 *phys)
{
      int ret, partial = 0;

      ret = ocfs2_map_page_blocks(page, phys, inode, from, to, 0);
      if (ret)
            mlog_errno(ret);

      if (zero)
            zero_user_segment(page, from, to);

      /*
       * Need to set the buffers we zero'd into uptodate
       * here if they aren't - ocfs2_map_page_blocks()
       * might've skipped some
       */
      ret = walk_page_buffers(handle, page_buffers(page),
                        from, to, &partial,
                        ocfs2_zero_func);
      if (ret < 0)
            mlog_errno(ret);
      else if (ocfs2_should_order_data(inode)) {
            ret = ocfs2_jbd2_file_inode(handle, inode);
            if (ret < 0)
                  mlog_errno(ret);
      }

      if (!partial)
            SetPageUptodate(page);

      flush_dcache_page(page);
}

static void ocfs2_zero_cluster_pages(struct inode *inode, loff_t start,
                             loff_t end, struct page **pages,
                             int numpages, u64 phys, handle_t *handle)
{
      int i;
      struct page *page;
      unsigned int from, to = PAGE_CACHE_SIZE;
      struct super_block *sb = inode->i_sb;

      BUG_ON(!ocfs2_sparse_alloc(OCFS2_SB(sb)));

      if (numpages == 0)
            goto out;

      to = PAGE_CACHE_SIZE;
      for(i = 0; i < numpages; i++) {
            page = pages[i];

            from = start & (PAGE_CACHE_SIZE - 1);
            if ((end >> PAGE_CACHE_SHIFT) == page->index)
                  to = end & (PAGE_CACHE_SIZE - 1);

            BUG_ON(from > PAGE_CACHE_SIZE);
            BUG_ON(to > PAGE_CACHE_SIZE);

            ocfs2_map_and_dirty_page(inode, handle, from, to, page, 1,
                               &phys);

            start = (page->index + 1) << PAGE_CACHE_SHIFT;
      }
out:
      if (pages)
            ocfs2_unlock_and_free_pages(pages, numpages);
}

static int ocfs2_grab_eof_pages(struct inode *inode, loff_t start, loff_t end,
                        struct page **pages, int *num)
{
      int numpages, ret = 0;
      struct super_block *sb = inode->i_sb;
      struct address_space *mapping = inode->i_mapping;
      unsigned long index;
      loff_t last_page_bytes;

      BUG_ON(start > end);

      BUG_ON(start >> OCFS2_SB(sb)->s_clustersize_bits !=
             (end - 1) >> OCFS2_SB(sb)->s_clustersize_bits);

      numpages = 0;
      last_page_bytes = PAGE_ALIGN(end);
      index = start >> PAGE_CACHE_SHIFT;
      do {
            pages[numpages] = grab_cache_page(mapping, index);
            if (!pages[numpages]) {
                  ret = -ENOMEM;
                  mlog_errno(ret);
                  goto out;
            }

            numpages++;
            index++;
      } while (index < (last_page_bytes >> PAGE_CACHE_SHIFT));

out:
      if (ret != 0) {
            if (pages)
                  ocfs2_unlock_and_free_pages(pages, numpages);
            numpages = 0;
      }

      *num = numpages;

      return ret;
}

/*
 * Zero the area past i_size but still within an allocated
 * cluster. This avoids exposing nonzero data on subsequent file
 * extends.
 *
 * We need to call this before i_size is updated on the inode because
 * otherwise block_write_full_page() will skip writeout of pages past
 * i_size. The new_i_size parameter is passed for this reason.
 */
int ocfs2_zero_range_for_truncate(struct inode *inode, handle_t *handle,
                          u64 range_start, u64 range_end)
{
      int ret = 0, numpages;
      struct page **pages = NULL;
      u64 phys;
      unsigned int ext_flags;
      struct super_block *sb = inode->i_sb;

      /*
       * File systems which don't support sparse files zero on every
       * extend.
       */
      if (!ocfs2_sparse_alloc(OCFS2_SB(sb)))
            return 0;

      pages = kcalloc(ocfs2_pages_per_cluster(sb),
                  sizeof(struct page *), GFP_NOFS);
      if (pages == NULL) {
            ret = -ENOMEM;
            mlog_errno(ret);
            goto out;
      }

      if (range_start == range_end)
            goto out;

      ret = ocfs2_extent_map_get_blocks(inode,
                                range_start >> sb->s_blocksize_bits,
                                &phys, NULL, &ext_flags);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      /*
       * Tail is a hole, or is marked unwritten. In either case, we
       * can count on read and write to return/push zero's.
       */
      if (phys == 0 || ext_flags & OCFS2_EXT_UNWRITTEN)
            goto out;

      ret = ocfs2_grab_eof_pages(inode, range_start, range_end, pages,
                           &numpages);
      if (ret) {
            mlog_errno(ret);
            goto out;
      }

      ocfs2_zero_cluster_pages(inode, range_start, range_end, pages,
                         numpages, phys, handle);

      /*
       * Initiate writeout of the pages we zero'd here. We don't
       * wait on them - the truncate_inode_pages() call later will
       * do that for us.
       */
      ret = do_sync_mapping_range(inode->i_mapping, range_start,
                            range_end - 1, SYNC_FILE_RANGE_WRITE);
      if (ret)
            mlog_errno(ret);

out:
      if (pages)
            kfree(pages);

      return ret;
}

static void ocfs2_zero_dinode_id2_with_xattr(struct inode *inode,
                                   struct ocfs2_dinode *di)
{
      unsigned int blocksize = 1 << inode->i_sb->s_blocksize_bits;
      unsigned int xattrsize = le16_to_cpu(di->i_xattr_inline_size);

      if (le16_to_cpu(di->i_dyn_features) & OCFS2_INLINE_XATTR_FL)
            memset(&di->id2, 0, blocksize -
                            offsetof(struct ocfs2_dinode, id2) -
                            xattrsize);
      else
            memset(&di->id2, 0, blocksize -
                            offsetof(struct ocfs2_dinode, id2));
}

void ocfs2_dinode_new_extent_list(struct inode *inode,
                          struct ocfs2_dinode *di)
{
      ocfs2_zero_dinode_id2_with_xattr(inode, di);
      di->id2.i_list.l_tree_depth = 0;
      di->id2.i_list.l_next_free_rec = 0;
      di->id2.i_list.l_count = cpu_to_le16(
            ocfs2_extent_recs_per_inode_with_xattr(inode->i_sb, di));
}

void ocfs2_set_inode_data_inline(struct inode *inode, struct ocfs2_dinode *di)
{
      struct ocfs2_inode_info *oi = OCFS2_I(inode);
      struct ocfs2_inline_data *idata = &di->id2.i_data;

      spin_lock(&oi->ip_lock);
      oi->ip_dyn_features |= OCFS2_INLINE_DATA_FL;
      di->i_dyn_features = cpu_to_le16(oi->ip_dyn_features);
      spin_unlock(&oi->ip_lock);

      /*
       * We clear the entire i_data structure here so that all
       * fields can be properly initialized.
       */
      ocfs2_zero_dinode_id2_with_xattr(inode, di);

      idata->id_count = cpu_to_le16(
                  ocfs2_max_inline_data_with_xattr(inode->i_sb, di));
}

int ocfs2_convert_inline_data_to_extents(struct inode *inode,
                               struct buffer_head *di_bh)
{
      int ret, i, has_data, num_pages = 0;
      handle_t *handle;
      u64 uninitialized_var(block);
      struct ocfs2_inode_info *oi = OCFS2_I(inode);
      struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
      struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
      struct ocfs2_alloc_context *data_ac = NULL;
      struct page **pages = NULL;
      loff_t end = osb->s_clustersize;
      struct ocfs2_extent_tree et;
      int did_quota = 0;

      has_data = i_size_read(inode) ? 1 : 0;

      if (has_data) {
            pages = kcalloc(ocfs2_pages_per_cluster(osb->sb),
                        sizeof(struct page *), GFP_NOFS);
            if (pages == NULL) {
                  ret = -ENOMEM;
                  mlog_errno(ret);
                  goto out;
            }

            ret = ocfs2_reserve_clusters(osb, 1, &data_ac);
            if (ret) {
                  mlog_errno(ret);
                  goto out;
            }
      }

      handle = ocfs2_start_trans(osb,
                           ocfs2_inline_to_extents_credits(osb->sb));
      if (IS_ERR(handle)) {
            ret = PTR_ERR(handle);
            mlog_errno(ret);
            goto out_unlock;
      }

      ret = ocfs2_journal_access_di(handle, inode, di_bh,
                              OCFS2_JOURNAL_ACCESS_WRITE);
      if (ret) {
            mlog_errno(ret);
            goto out_commit;
      }

      if (has_data) {
            u32 bit_off, num;
            unsigned int page_end;
            u64 phys;

            if (vfs_dq_alloc_space_nodirty(inode,
                               ocfs2_clusters_to_bytes(osb->sb, 1))) {
                  ret = -EDQUOT;
                  goto out_commit;
            }
            did_quota = 1;

            ret = ocfs2_claim_clusters(osb, handle, data_ac, 1, &bit_off,
                                 &num);
            if (ret) {
                  mlog_errno(ret);
                  goto out_commit;
            }

            /*
             * Save two copies, one for insert, and one that can
             * be changed by ocfs2_map_and_dirty_page() below.
             */
            block = phys = ocfs2_clusters_to_blocks(inode->i_sb, bit_off);

            /*
             * Non sparse file systems zero on extend, so no need
             * to do that now.
             */
            if (!ocfs2_sparse_alloc(osb) &&
                PAGE_CACHE_SIZE < osb->s_clustersize)
                  end = PAGE_CACHE_SIZE;

            ret = ocfs2_grab_eof_pages(inode, 0, end, pages, &num_pages);
            if (ret) {
                  mlog_errno(ret);
                  goto out_commit;
            }

            /*
             * This should populate the 1st page for us and mark
             * it up to date.
             */
            ret = ocfs2_read_inline_data(inode, pages[0], di_bh);
            if (ret) {
                  mlog_errno(ret);
                  goto out_commit;
            }

            page_end = PAGE_CACHE_SIZE;
            if (PAGE_CACHE_SIZE > osb->s_clustersize)
                  page_end = osb->s_clustersize;

            for (i = 0; i < num_pages; i++)
                  ocfs2_map_and_dirty_page(inode, handle, 0, page_end,
                                     pages[i], i > 0, &phys);
      }

      spin_lock(&oi->ip_lock);
      oi->ip_dyn_features &= ~OCFS2_INLINE_DATA_FL;
      di->i_dyn_features = cpu_to_le16(oi->ip_dyn_features);
      spin_unlock(&oi->ip_lock);

      ocfs2_dinode_new_extent_list(inode, di);

      ocfs2_journal_dirty(handle, di_bh);

      if (has_data) {
            /*
             * An error at this point should be extremely rare. If
             * this proves to be false, we could always re-build
             * the in-inode data from our pages.
             */
            ocfs2_init_dinode_extent_tree(&et, inode, di_bh);
            ret = ocfs2_insert_extent(osb, handle, inode, &et,
                                0, block, 1, 0, NULL);
            if (ret) {
                  mlog_errno(ret);
                  goto out_commit;
            }

            inode->i_blocks = ocfs2_inode_sector_count(inode);
      }

out_commit:
      if (ret < 0 && did_quota)
            vfs_dq_free_space_nodirty(inode,
                                ocfs2_clusters_to_bytes(osb->sb, 1));

      ocfs2_commit_trans(osb, handle);

out_unlock:
      if (data_ac)
            ocfs2_free_alloc_context(data_ac);

out:
      if (pages) {
            ocfs2_unlock_and_free_pages(pages, num_pages);
            kfree(pages);
      }

      return ret;
}

/*
 * It is expected, that by the time you call this function,
 * inode->i_size and fe->i_size have been adjusted.
 *
 * WARNING: This will kfree the truncate context
 */
int ocfs2_commit_truncate(struct ocfs2_super *osb,
                    struct inode *inode,
                    struct buffer_head *fe_bh,
                    struct ocfs2_truncate_context *tc)
{
      int status, i, credits, tl_sem = 0;
      u32 clusters_to_del, new_highest_cpos, range;
      struct ocfs2_extent_list *el;
      handle_t *handle = NULL;
      struct inode *tl_inode = osb->osb_tl_inode;
      struct ocfs2_path *path = NULL;
      struct ocfs2_dinode *di = (struct ocfs2_dinode *)fe_bh->b_data;

      mlog_entry_void();

      new_highest_cpos = ocfs2_clusters_for_bytes(osb->sb,
                                         i_size_read(inode));

      path = ocfs2_new_path(fe_bh, &di->id2.i_list,
                        ocfs2_journal_access_di);
      if (!path) {
            status = -ENOMEM;
            mlog_errno(status);
            goto bail;
      }

      ocfs2_extent_map_trunc(inode, new_highest_cpos);

start:
      /*
       * Check that we still have allocation to delete.
       */
      if (OCFS2_I(inode)->ip_clusters == 0) {
            status = 0;
            goto bail;
      }

      /*
       * Truncate always works against the rightmost tree branch.
       */
      status = ocfs2_find_path(inode, path, UINT_MAX);
      if (status) {
            mlog_errno(status);
            goto bail;
      }

      mlog(0, "inode->ip_clusters = %u, tree_depth = %u\n",
           OCFS2_I(inode)->ip_clusters, path->p_tree_depth);

      /*
       * By now, el will point to the extent list on the bottom most
       * portion of this tree. Only the tail record is considered in
       * each pass.
       *
       * We handle the following cases, in order:
       * - empty extent: delete the remaining branch
       * - remove the entire record
       * - remove a partial record
       * - no record needs to be removed (truncate has completed)
       */
      el = path_leaf_el(path);
      if (le16_to_cpu(el->l_next_free_rec) == 0) {
            ocfs2_error(inode->i_sb,
                      "Inode %llu has empty extent block at %llu\n",
                      (unsigned long long)OCFS2_I(inode)->ip_blkno,
                      (unsigned long long)path_leaf_bh(path)->b_blocknr);
            status = -EROFS;
            goto bail;
      }

      i = le16_to_cpu(el->l_next_free_rec) - 1;
      range = le32_to_cpu(el->l_recs[i].e_cpos) +
            ocfs2_rec_clusters(el, &el->l_recs[i]);
      if (i == 0 && ocfs2_is_empty_extent(&el->l_recs[i])) {
            clusters_to_del = 0;
      } else if (le32_to_cpu(el->l_recs[i].e_cpos) >= new_highest_cpos) {
            clusters_to_del = ocfs2_rec_clusters(el, &el->l_recs[i]);
      } else if (range > new_highest_cpos) {
            clusters_to_del = (ocfs2_rec_clusters(el, &el->l_recs[i]) +
                           le32_to_cpu(el->l_recs[i].e_cpos)) -
                          new_highest_cpos;
      } else {
            status = 0;
            goto bail;
      }

      mlog(0, "clusters_to_del = %u in this pass, tail blk=%llu\n",
           clusters_to_del, (unsigned long long)path_leaf_bh(path)->b_blocknr);

      mutex_lock(&tl_inode->i_mutex);
      tl_sem = 1;
      /* ocfs2_truncate_log_needs_flush guarantees us at least one
       * record is free for use. If there isn't any, we flush to get
       * an empty truncate log.  */
      if (ocfs2_truncate_log_needs_flush(osb)) {
            status = __ocfs2_flush_truncate_log(osb);
            if (status < 0) {
                  mlog_errno(status);
                  goto bail;
            }
      }

      credits = ocfs2_calc_tree_trunc_credits(osb->sb, clusters_to_del,
                                    (struct ocfs2_dinode *)fe_bh->b_data,
                                    el);
      handle = ocfs2_start_trans(osb, credits);
      if (IS_ERR(handle)) {
            status = PTR_ERR(handle);
            handle = NULL;
            mlog_errno(status);
            goto bail;
      }

      status = ocfs2_do_truncate(osb, clusters_to_del, inode, fe_bh, handle,
                           tc, path);
      if (status < 0) {
            mlog_errno(status);
            goto bail;
      }

      mutex_unlock(&tl_inode->i_mutex);
      tl_sem = 0;

      ocfs2_commit_trans(osb, handle);
      handle = NULL;

      ocfs2_reinit_path(path, 1);

      /*
       * The check above will catch the case where we've truncated
       * away all allocation.
       */
      goto start;

bail:

      ocfs2_schedule_truncate_log_flush(osb, 1);

      if (tl_sem)
            mutex_unlock(&tl_inode->i_mutex);

      if (handle)
            ocfs2_commit_trans(osb, handle);

      ocfs2_run_deallocs(osb, &tc->tc_dealloc);

      ocfs2_free_path(path);

      /* This will drop the ext_alloc cluster lock for us */
      ocfs2_free_truncate_context(tc);

      mlog_exit(status);
      return status;
}

/*
 * Expects the inode to already be locked.
 */
int ocfs2_prepare_truncate(struct ocfs2_super *osb,
                     struct inode *inode,
                     struct buffer_head *fe_bh,
                     struct ocfs2_truncate_context **tc)
{
      int status;
      unsigned int new_i_clusters;
      struct ocfs2_dinode *fe;
      struct ocfs2_extent_block *eb;
      struct buffer_head *last_eb_bh = NULL;

      mlog_entry_void();

      *tc = NULL;

      new_i_clusters = ocfs2_clusters_for_bytes(osb->sb,
                                      i_size_read(inode));
      fe = (struct ocfs2_dinode *) fe_bh->b_data;

      mlog(0, "fe->i_clusters = %u, new_i_clusters = %u, fe->i_size ="
           "%llu\n", le32_to_cpu(fe->i_clusters), new_i_clusters,
           (unsigned long long)le64_to_cpu(fe->i_size));

      *tc = kzalloc(sizeof(struct ocfs2_truncate_context), GFP_KERNEL);
      if (!(*tc)) {
            status = -ENOMEM;
            mlog_errno(status);
            goto bail;
      }
      ocfs2_init_dealloc_ctxt(&(*tc)->tc_dealloc);

      if (fe->id2.i_list.l_tree_depth) {
            status = ocfs2_read_extent_block(inode,
                                     le64_to_cpu(fe->i_last_eb_blk),
                                     &last_eb_bh);
            if (status < 0) {
                  mlog_errno(status);
                  goto bail;
            }
            eb = (struct ocfs2_extent_block *) last_eb_bh->b_data;
      }

      (*tc)->tc_last_eb_bh = last_eb_bh;

      status = 0;
bail:
      if (status < 0) {
            if (*tc)
                  ocfs2_free_truncate_context(*tc);
            *tc = NULL;
      }
      mlog_exit_void();
      return status;
}

/*
 * 'start' is inclusive, 'end' is not.
 */
int ocfs2_truncate_inline(struct inode *inode, struct buffer_head *di_bh,
                    unsigned int start, unsigned int end, int trunc)
{
      int ret;
      unsigned int numbytes;
      handle_t *handle;
      struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
      struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
      struct ocfs2_inline_data *idata = &di->id2.i_data;

      if (end > i_size_read(inode))
            end = i_size_read(inode);

      BUG_ON(start >= end);

      if (!(OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL) ||
          !(le16_to_cpu(di->i_dyn_features) & OCFS2_INLINE_DATA_FL) ||
          !ocfs2_supports_inline_data(osb)) {
            ocfs2_error(inode->i_sb,
                      "Inline data flags for inode %llu don't agree! "
                      "Disk: 0x%x, Memory: 0x%x, Superblock: 0x%x\n",
                      (unsigned long long)OCFS2_I(inode)->ip_blkno,
                      le16_to_cpu(di->i_dyn_features),
                      OCFS2_I(inode)->ip_dyn_features,
                      osb->s_feature_incompat);
            ret = -EROFS;
            goto out;
      }

      handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
      if (IS_ERR(handle)) {
            ret = PTR_ERR(handle);
            mlog_errno(ret);
            goto out;
      }

      ret = ocfs2_journal_access_di(handle, inode, di_bh,
                              OCFS2_JOURNAL_ACCESS_WRITE);
      if (ret) {
            mlog_errno(ret);
            goto out_commit;
      }

      numbytes = end - start;
      memset(idata->id_data + start, 0, numbytes);

      /*
       * No need to worry about the data page here - it's been
       * truncated already and inline data doesn't need it for
       * pushing zero's to disk, so we'll let readpage pick it up
       * later.
       */
      if (trunc) {
            i_size_write(inode, start);
            di->i_size = cpu_to_le64(start);
      }

      inode->i_blocks = ocfs2_inode_sector_count(inode);
      inode->i_ctime = inode->i_mtime = CURRENT_TIME;

      di->i_ctime = di->i_mtime = cpu_to_le64(inode->i_ctime.tv_sec);
      di->i_ctime_nsec = di->i_mtime_nsec = cpu_to_le32(inode->i_ctime.tv_nsec);

      ocfs2_journal_dirty(handle, di_bh);

out_commit:
      ocfs2_commit_trans(osb, handle);

out:
      return ret;
}

static void ocfs2_free_truncate_context(struct ocfs2_truncate_context *tc)
{
      /*
       * The caller is responsible for completing deallocation
       * before freeing the context.
       */
      if (tc->tc_dealloc.c_first_suballocator != NULL)
            mlog(ML_NOTICE,
                 "Truncate completion has non-empty dealloc context\n");

      brelse(tc->tc_last_eb_bh);

      kfree(tc);
}

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