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xfs_btree.c

/*
 * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
 * 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.
 *
 * This program is distributed in the hope that it would 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 the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_types.h"
#include "xfs_bit.h"
#include "xfs_log.h"
#include "xfs_inum.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_dir2.h"
#include "xfs_dmapi.h"
#include "xfs_mount.h"
#include "xfs_bmap_btree.h"
#include "xfs_alloc_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_dir2_sf.h"
#include "xfs_attr_sf.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_inode_item.h"
#include "xfs_btree.h"
#include "xfs_btree_trace.h"
#include "xfs_ialloc.h"
#include "xfs_error.h"

/*
 * Cursor allocation zone.
 */
kmem_zone_t *xfs_btree_cur_zone;

/*
 * Btree magic numbers.
 */
const __uint32_t xfs_magics[XFS_BTNUM_MAX] = {
      XFS_ABTB_MAGIC, XFS_ABTC_MAGIC, XFS_BMAP_MAGIC, XFS_IBT_MAGIC
};


STATIC int                    /* error (0 or EFSCORRUPTED) */
xfs_btree_check_lblock(
      struct xfs_btree_cur    *cur, /* btree cursor */
      struct xfs_btree_block  *block,     /* btree long form block pointer */
      int               level,      /* level of the btree block */
      struct xfs_buf          *bp)  /* buffer for block, if any */
{
      int               lblock_ok; /* block passes checks */
      struct xfs_mount  *mp;  /* file system mount point */

      mp = cur->bc_mp;
      lblock_ok =
            be32_to_cpu(block->bb_magic) == xfs_magics[cur->bc_btnum] &&
            be16_to_cpu(block->bb_level) == level &&
            be16_to_cpu(block->bb_numrecs) <=
                  cur->bc_ops->get_maxrecs(cur, level) &&
            block->bb_u.l.bb_leftsib &&
            (be64_to_cpu(block->bb_u.l.bb_leftsib) == NULLDFSBNO ||
             XFS_FSB_SANITY_CHECK(mp,
                  be64_to_cpu(block->bb_u.l.bb_leftsib))) &&
            block->bb_u.l.bb_rightsib &&
            (be64_to_cpu(block->bb_u.l.bb_rightsib) == NULLDFSBNO ||
             XFS_FSB_SANITY_CHECK(mp,
                  be64_to_cpu(block->bb_u.l.bb_rightsib)));
      if (unlikely(XFS_TEST_ERROR(!lblock_ok, mp,
                  XFS_ERRTAG_BTREE_CHECK_LBLOCK,
                  XFS_RANDOM_BTREE_CHECK_LBLOCK))) {
            if (bp)
                  xfs_buftrace("LBTREE ERROR", bp);
            XFS_ERROR_REPORT("xfs_btree_check_lblock", XFS_ERRLEVEL_LOW,
                         mp);
            return XFS_ERROR(EFSCORRUPTED);
      }
      return 0;
}

STATIC int                    /* error (0 or EFSCORRUPTED) */
xfs_btree_check_sblock(
      struct xfs_btree_cur    *cur, /* btree cursor */
      struct xfs_btree_block  *block,     /* btree short form block pointer */
      int               level,      /* level of the btree block */
      struct xfs_buf          *bp)  /* buffer containing block */
{
      struct xfs_buf          *agbp;      /* buffer for ag. freespace struct */
      struct xfs_agf          *agf; /* ag. freespace structure */
      xfs_agblock_t           agflen;     /* native ag. freespace length */
      int               sblock_ok; /* block passes checks */

      agbp = cur->bc_private.a.agbp;
      agf = XFS_BUF_TO_AGF(agbp);
      agflen = be32_to_cpu(agf->agf_length);
      sblock_ok =
            be32_to_cpu(block->bb_magic) == xfs_magics[cur->bc_btnum] &&
            be16_to_cpu(block->bb_level) == level &&
            be16_to_cpu(block->bb_numrecs) <=
                  cur->bc_ops->get_maxrecs(cur, level) &&
            (be32_to_cpu(block->bb_u.s.bb_leftsib) == NULLAGBLOCK ||
             be32_to_cpu(block->bb_u.s.bb_leftsib) < agflen) &&
            block->bb_u.s.bb_leftsib &&
            (be32_to_cpu(block->bb_u.s.bb_rightsib) == NULLAGBLOCK ||
             be32_to_cpu(block->bb_u.s.bb_rightsib) < agflen) &&
            block->bb_u.s.bb_rightsib;
      if (unlikely(XFS_TEST_ERROR(!sblock_ok, cur->bc_mp,
                  XFS_ERRTAG_BTREE_CHECK_SBLOCK,
                  XFS_RANDOM_BTREE_CHECK_SBLOCK))) {
            if (bp)
                  xfs_buftrace("SBTREE ERROR", bp);
            XFS_CORRUPTION_ERROR("xfs_btree_check_sblock",
                  XFS_ERRLEVEL_LOW, cur->bc_mp, block);
            return XFS_ERROR(EFSCORRUPTED);
      }
      return 0;
}

/*
 * Debug routine: check that block header is ok.
 */
int
xfs_btree_check_block(
      struct xfs_btree_cur    *cur, /* btree cursor */
      struct xfs_btree_block  *block,     /* generic btree block pointer */
      int               level,      /* level of the btree block */
      struct xfs_buf          *bp)  /* buffer containing block, if any */
{
      if (cur->bc_flags & XFS_BTREE_LONG_PTRS)
            return xfs_btree_check_lblock(cur, block, level, bp);
      else
            return xfs_btree_check_sblock(cur, block, level, bp);
}

/*
 * Check that (long) pointer is ok.
 */
int                           /* error (0 or EFSCORRUPTED) */
xfs_btree_check_lptr(
      struct xfs_btree_cur    *cur, /* btree cursor */
      xfs_dfsbno_t            bno,  /* btree block disk address */
      int               level)      /* btree block level */
{
      XFS_WANT_CORRUPTED_RETURN(
            level > 0 &&
            bno != NULLDFSBNO &&
            XFS_FSB_SANITY_CHECK(cur->bc_mp, bno));
      return 0;
}

#ifdef DEBUG
/*
 * Check that (short) pointer is ok.
 */
STATIC int                    /* error (0 or EFSCORRUPTED) */
xfs_btree_check_sptr(
      struct xfs_btree_cur    *cur, /* btree cursor */
      xfs_agblock_t           bno,  /* btree block disk address */
      int               level)      /* btree block level */
{
      xfs_agblock_t           agblocks = cur->bc_mp->m_sb.sb_agblocks;

      XFS_WANT_CORRUPTED_RETURN(
            level > 0 &&
            bno != NULLAGBLOCK &&
            bno != 0 &&
            bno < agblocks);
      return 0;
}

/*
 * Check that block ptr is ok.
 */
STATIC int                    /* error (0 or EFSCORRUPTED) */
xfs_btree_check_ptr(
      struct xfs_btree_cur    *cur, /* btree cursor */
      union xfs_btree_ptr     *ptr, /* btree block disk address */
      int               index,      /* offset from ptr to check */
      int               level)      /* btree block level */
{
      if (cur->bc_flags & XFS_BTREE_LONG_PTRS) {
            return xfs_btree_check_lptr(cur,
                        be64_to_cpu((&ptr->l)[index]), level);
      } else {
            return xfs_btree_check_sptr(cur,
                        be32_to_cpu((&ptr->s)[index]), level);
      }
}
#endif

/*
 * Delete the btree cursor.
 */
void
xfs_btree_del_cursor(
      xfs_btree_cur_t   *cur,       /* btree cursor */
      int         error)            /* del because of error */
{
      int         i;          /* btree level */

      /*
       * Clear the buffer pointers, and release the buffers.
       * If we're doing this in the face of an error, we
       * need to make sure to inspect all of the entries
       * in the bc_bufs array for buffers to be unlocked.
       * This is because some of the btree code works from
       * level n down to 0, and if we get an error along
       * the way we won't have initialized all the entries
       * down to 0.
       */
      for (i = 0; i < cur->bc_nlevels; i++) {
            if (cur->bc_bufs[i])
                  xfs_btree_setbuf(cur, i, NULL);
            else if (!error)
                  break;
      }
      /*
       * Can't free a bmap cursor without having dealt with the
       * allocated indirect blocks' accounting.
       */
      ASSERT(cur->bc_btnum != XFS_BTNUM_BMAP ||
             cur->bc_private.b.allocated == 0);
      /*
       * Free the cursor.
       */
      kmem_zone_free(xfs_btree_cur_zone, cur);
}

/*
 * Duplicate the btree cursor.
 * Allocate a new one, copy the record, re-get the buffers.
 */
int                           /* error */
xfs_btree_dup_cursor(
      xfs_btree_cur_t   *cur,       /* input cursor */
      xfs_btree_cur_t   **ncur)           /* output cursor */
{
      xfs_buf_t   *bp;        /* btree block's buffer pointer */
      int         error;            /* error return value */
      int         i;          /* level number of btree block */
      xfs_mount_t *mp;        /* mount structure for filesystem */
      xfs_btree_cur_t   *new;       /* new cursor value */
      xfs_trans_t *tp;        /* transaction pointer, can be NULL */

      tp = cur->bc_tp;
      mp = cur->bc_mp;

      /*
       * Allocate a new cursor like the old one.
       */
      new = cur->bc_ops->dup_cursor(cur);

      /*
       * Copy the record currently in the cursor.
       */
      new->bc_rec = cur->bc_rec;

      /*
       * For each level current, re-get the buffer and copy the ptr value.
       */
      for (i = 0; i < new->bc_nlevels; i++) {
            new->bc_ptrs[i] = cur->bc_ptrs[i];
            new->bc_ra[i] = cur->bc_ra[i];
            if ((bp = cur->bc_bufs[i])) {
                  if ((error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp,
                        XFS_BUF_ADDR(bp), mp->m_bsize, 0, &bp))) {
                        xfs_btree_del_cursor(new, error);
                        *ncur = NULL;
                        return error;
                  }
                  new->bc_bufs[i] = bp;
                  ASSERT(bp);
                  ASSERT(!XFS_BUF_GETERROR(bp));
            } else
                  new->bc_bufs[i] = NULL;
      }
      *ncur = new;
      return 0;
}

/*
 * XFS btree block layout and addressing:
 *
 * There are two types of blocks in the btree: leaf and non-leaf blocks.
 *
 * The leaf record start with a header then followed by records containing
 * the values.  A non-leaf block also starts with the same header, and
 * then first contains lookup keys followed by an equal number of pointers
 * to the btree blocks at the previous level.
 *
 *          +--------+-------+-------+-------+-------+-------+-------+
 * Leaf:    | header | rec 1 | rec 2 | rec 3 | rec 4 | rec 5 | rec N |
 *          +--------+-------+-------+-------+-------+-------+-------+
 *
 *          +--------+-------+-------+-------+-------+-------+-------+
 * Non-Leaf:      | header | key 1 | key 2 | key N | ptr 1 | ptr 2 | ptr N |
 *          +--------+-------+-------+-------+-------+-------+-------+
 *
 * The header is called struct xfs_btree_block for reasons better left unknown
 * and comes in different versions for short (32bit) and long (64bit) block
 * pointers.  The record and key structures are defined by the btree instances
 * and opaque to the btree core.  The block pointers are simple disk endian
 * integers, available in a short (32bit) and long (64bit) variant.
 *
 * The helpers below calculate the offset of a given record, key or pointer
 * into a btree block (xfs_btree_*_offset) or return a pointer to the given
 * record, key or pointer (xfs_btree_*_addr).  Note that all addressing
 * inside the btree block is done using indices starting at one, not zero!
 */

/*
 * Return size of the btree block header for this btree instance.
 */
static inline size_t xfs_btree_block_len(struct xfs_btree_cur *cur)
{
      return (cur->bc_flags & XFS_BTREE_LONG_PTRS) ?
            XFS_BTREE_LBLOCK_LEN :
            XFS_BTREE_SBLOCK_LEN;
}

/*
 * Return size of btree block pointers for this btree instance.
 */
static inline size_t xfs_btree_ptr_len(struct xfs_btree_cur *cur)
{
      return (cur->bc_flags & XFS_BTREE_LONG_PTRS) ?
            sizeof(__be64) : sizeof(__be32);
}

/*
 * Calculate offset of the n-th record in a btree block.
 */
STATIC size_t
xfs_btree_rec_offset(
      struct xfs_btree_cur    *cur,
      int               n)
{
      return xfs_btree_block_len(cur) +
            (n - 1) * cur->bc_ops->rec_len;
}

/*
 * Calculate offset of the n-th key in a btree block.
 */
STATIC size_t
xfs_btree_key_offset(
      struct xfs_btree_cur    *cur,
      int               n)
{
      return xfs_btree_block_len(cur) +
            (n - 1) * cur->bc_ops->key_len;
}

/*
 * Calculate offset of the n-th block pointer in a btree block.
 */
STATIC size_t
xfs_btree_ptr_offset(
      struct xfs_btree_cur    *cur,
      int               n,
      int               level)
{
      return xfs_btree_block_len(cur) +
            cur->bc_ops->get_maxrecs(cur, level) * cur->bc_ops->key_len +
            (n - 1) * xfs_btree_ptr_len(cur);
}

/*
 * Return a pointer to the n-th record in the btree block.
 */
STATIC union xfs_btree_rec *
xfs_btree_rec_addr(
      struct xfs_btree_cur    *cur,
      int               n,
      struct xfs_btree_block  *block)
{
      return (union xfs_btree_rec *)
            ((char *)block + xfs_btree_rec_offset(cur, n));
}

/*
 * Return a pointer to the n-th key in the btree block.
 */
STATIC union xfs_btree_key *
xfs_btree_key_addr(
      struct xfs_btree_cur    *cur,
      int               n,
      struct xfs_btree_block  *block)
{
      return (union xfs_btree_key *)
            ((char *)block + xfs_btree_key_offset(cur, n));
}

/*
 * Return a pointer to the n-th block pointer in the btree block.
 */
STATIC union xfs_btree_ptr *
xfs_btree_ptr_addr(
      struct xfs_btree_cur    *cur,
      int               n,
      struct xfs_btree_block  *block)
{
      int               level = xfs_btree_get_level(block);

      ASSERT(block->bb_level != 0);

      return (union xfs_btree_ptr *)
            ((char *)block + xfs_btree_ptr_offset(cur, n, level));
}

/*
 * Get a the root block which is stored in the inode.
 *
 * For now this btree implementation assumes the btree root is always
 * stored in the if_broot field of an inode fork.
 */
STATIC struct xfs_btree_block *
xfs_btree_get_iroot(
       struct xfs_btree_cur    *cur)
{
       struct xfs_ifork        *ifp;

       ifp = XFS_IFORK_PTR(cur->bc_private.b.ip, cur->bc_private.b.whichfork);
       return (struct xfs_btree_block *)ifp->if_broot;
}

/*
 * Retrieve the block pointer from the cursor at the given level.
 * This may be an inode btree root or from a buffer.
 */
STATIC struct xfs_btree_block *           /* generic btree block pointer */
xfs_btree_get_block(
      struct xfs_btree_cur    *cur, /* btree cursor */
      int               level,      /* level in btree */
      struct xfs_buf          **bpp)      /* buffer containing the block */
{
      if ((cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) &&
          (level == cur->bc_nlevels - 1)) {
            *bpp = NULL;
            return xfs_btree_get_iroot(cur);
      }

      *bpp = cur->bc_bufs[level];
      return XFS_BUF_TO_BLOCK(*bpp);
}

/*
 * Get a buffer for the block, return it with no data read.
 * Long-form addressing.
 */
xfs_buf_t *                   /* buffer for fsbno */
xfs_btree_get_bufl(
      xfs_mount_t *mp,        /* file system mount point */
      xfs_trans_t *tp,        /* transaction pointer */
      xfs_fsblock_t     fsbno,            /* file system block number */
      uint        lock)       /* lock flags for get_buf */
{
      xfs_buf_t   *bp;        /* buffer pointer (return value) */
      xfs_daddr_t       d;          /* real disk block address */

      ASSERT(fsbno != NULLFSBLOCK);
      d = XFS_FSB_TO_DADDR(mp, fsbno);
      bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, d, mp->m_bsize, lock);
      ASSERT(bp);
      ASSERT(!XFS_BUF_GETERROR(bp));
      return bp;
}

/*
 * Get a buffer for the block, return it with no data read.
 * Short-form addressing.
 */
xfs_buf_t *                   /* buffer for agno/agbno */
xfs_btree_get_bufs(
      xfs_mount_t *mp,        /* file system mount point */
      xfs_trans_t *tp,        /* transaction pointer */
      xfs_agnumber_t    agno,       /* allocation group number */
      xfs_agblock_t     agbno,            /* allocation group block number */
      uint        lock)       /* lock flags for get_buf */
{
      xfs_buf_t   *bp;        /* buffer pointer (return value) */
      xfs_daddr_t       d;          /* real disk block address */

      ASSERT(agno != NULLAGNUMBER);
      ASSERT(agbno != NULLAGBLOCK);
      d = XFS_AGB_TO_DADDR(mp, agno, agbno);
      bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, d, mp->m_bsize, lock);
      ASSERT(bp);
      ASSERT(!XFS_BUF_GETERROR(bp));
      return bp;
}

/*
 * Check for the cursor referring to the last block at the given level.
 */
int                           /* 1=is last block, 0=not last block */
xfs_btree_islastblock(
      xfs_btree_cur_t         *cur, /* btree cursor */
      int               level)      /* level to check */
{
      struct xfs_btree_block  *block;     /* generic btree block pointer */
      xfs_buf_t         *bp;  /* buffer containing block */

      block = xfs_btree_get_block(cur, level, &bp);
      xfs_btree_check_block(cur, block, level, bp);
      if (cur->bc_flags & XFS_BTREE_LONG_PTRS)
            return be64_to_cpu(block->bb_u.l.bb_rightsib) == NULLDFSBNO;
      else
            return be32_to_cpu(block->bb_u.s.bb_rightsib) == NULLAGBLOCK;
}

/*
 * Change the cursor to point to the first record at the given level.
 * Other levels are unaffected.
 */
STATIC int                    /* success=1, failure=0 */
xfs_btree_firstrec(
      xfs_btree_cur_t         *cur, /* btree cursor */
      int               level)      /* level to change */
{
      struct xfs_btree_block  *block;     /* generic btree block pointer */
      xfs_buf_t         *bp;  /* buffer containing block */

      /*
       * Get the block pointer for this level.
       */
      block = xfs_btree_get_block(cur, level, &bp);
      xfs_btree_check_block(cur, block, level, bp);
      /*
       * It's empty, there is no such record.
       */
      if (!block->bb_numrecs)
            return 0;
      /*
       * Set the ptr value to 1, that's the first record/key.
       */
      cur->bc_ptrs[level] = 1;
      return 1;
}

/*
 * Change the cursor to point to the last record in the current block
 * at the given level.  Other levels are unaffected.
 */
STATIC int                    /* success=1, failure=0 */
xfs_btree_lastrec(
      xfs_btree_cur_t         *cur, /* btree cursor */
      int               level)      /* level to change */
{
      struct xfs_btree_block  *block;     /* generic btree block pointer */
      xfs_buf_t         *bp;  /* buffer containing block */

      /*
       * Get the block pointer for this level.
       */
      block = xfs_btree_get_block(cur, level, &bp);
      xfs_btree_check_block(cur, block, level, bp);
      /*
       * It's empty, there is no such record.
       */
      if (!block->bb_numrecs)
            return 0;
      /*
       * Set the ptr value to numrecs, that's the last record/key.
       */
      cur->bc_ptrs[level] = be16_to_cpu(block->bb_numrecs);
      return 1;
}

/*
 * Compute first and last byte offsets for the fields given.
 * Interprets the offsets table, which contains struct field offsets.
 */
void
xfs_btree_offsets(
      __int64_t   fields,           /* bitmask of fields */
      const short *offsets,   /* table of field offsets */
      int         nbits,            /* number of bits to inspect */
      int         *first,           /* output: first byte offset */
      int         *last)            /* output: last byte offset */
{
      int         i;          /* current bit number */
      __int64_t   imask;            /* mask for current bit number */

      ASSERT(fields != 0);
      /*
       * Find the lowest bit, so the first byte offset.
       */
      for (i = 0, imask = 1LL; ; i++, imask <<= 1) {
            if (imask & fields) {
                  *first = offsets[i];
                  break;
            }
      }
      /*
       * Find the highest bit, so the last byte offset.
       */
      for (i = nbits - 1, imask = 1LL << i; ; i--, imask >>= 1) {
            if (imask & fields) {
                  *last = offsets[i + 1] - 1;
                  break;
            }
      }
}

/*
 * Get a buffer for the block, return it read in.
 * Long-form addressing.
 */
int                           /* error */
xfs_btree_read_bufl(
      xfs_mount_t *mp,        /* file system mount point */
      xfs_trans_t *tp,        /* transaction pointer */
      xfs_fsblock_t     fsbno,            /* file system block number */
      uint        lock,       /* lock flags for read_buf */
      xfs_buf_t   **bpp,            /* buffer for fsbno */
      int         refval)           /* ref count value for buffer */
{
      xfs_buf_t   *bp;        /* return value */
      xfs_daddr_t       d;          /* real disk block address */
      int         error;

      ASSERT(fsbno != NULLFSBLOCK);
      d = XFS_FSB_TO_DADDR(mp, fsbno);
      if ((error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp, d,
                  mp->m_bsize, lock, &bp))) {
            return error;
      }
      ASSERT(!bp || !XFS_BUF_GETERROR(bp));
      if (bp != NULL) {
            XFS_BUF_SET_VTYPE_REF(bp, B_FS_MAP, refval);
      }
      *bpp = bp;
      return 0;
}

/*
 * Get a buffer for the block, return it read in.
 * Short-form addressing.
 */
int                           /* error */
xfs_btree_read_bufs(
      xfs_mount_t *mp,        /* file system mount point */
      xfs_trans_t *tp,        /* transaction pointer */
      xfs_agnumber_t    agno,       /* allocation group number */
      xfs_agblock_t     agbno,            /* allocation group block number */
      uint        lock,       /* lock flags for read_buf */
      xfs_buf_t   **bpp,            /* buffer for agno/agbno */
      int         refval)           /* ref count value for buffer */
{
      xfs_buf_t   *bp;        /* return value */
      xfs_daddr_t d;          /* real disk block address */
      int         error;

      ASSERT(agno != NULLAGNUMBER);
      ASSERT(agbno != NULLAGBLOCK);
      d = XFS_AGB_TO_DADDR(mp, agno, agbno);
      if ((error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp, d,
                              mp->m_bsize, lock, &bp))) {
            return error;
      }
      ASSERT(!bp || !XFS_BUF_GETERROR(bp));
      if (bp != NULL) {
            switch (refval) {
            case XFS_ALLOC_BTREE_REF:
                  XFS_BUF_SET_VTYPE_REF(bp, B_FS_MAP, refval);
                  break;
            case XFS_INO_BTREE_REF:
                  XFS_BUF_SET_VTYPE_REF(bp, B_FS_INOMAP, refval);
                  break;
            }
      }
      *bpp = bp;
      return 0;
}

/*
 * Read-ahead the block, don't wait for it, don't return a buffer.
 * Long-form addressing.
 */
/* ARGSUSED */
void
xfs_btree_reada_bufl(
      xfs_mount_t *mp,        /* file system mount point */
      xfs_fsblock_t     fsbno,            /* file system block number */
      xfs_extlen_t      count)            /* count of filesystem blocks */
{
      xfs_daddr_t       d;

      ASSERT(fsbno != NULLFSBLOCK);
      d = XFS_FSB_TO_DADDR(mp, fsbno);
      xfs_baread(mp->m_ddev_targp, d, mp->m_bsize * count);
}

/*
 * Read-ahead the block, don't wait for it, don't return a buffer.
 * Short-form addressing.
 */
/* ARGSUSED */
void
xfs_btree_reada_bufs(
      xfs_mount_t *mp,        /* file system mount point */
      xfs_agnumber_t    agno,       /* allocation group number */
      xfs_agblock_t     agbno,            /* allocation group block number */
      xfs_extlen_t      count)            /* count of filesystem blocks */
{
      xfs_daddr_t       d;

      ASSERT(agno != NULLAGNUMBER);
      ASSERT(agbno != NULLAGBLOCK);
      d = XFS_AGB_TO_DADDR(mp, agno, agbno);
      xfs_baread(mp->m_ddev_targp, d, mp->m_bsize * count);
}

STATIC int
xfs_btree_readahead_lblock(
      struct xfs_btree_cur    *cur,
      int               lr,
      struct xfs_btree_block  *block)
{
      int               rval = 0;
      xfs_dfsbno_t            left = be64_to_cpu(block->bb_u.l.bb_leftsib);
      xfs_dfsbno_t            right = be64_to_cpu(block->bb_u.l.bb_rightsib);

      if ((lr & XFS_BTCUR_LEFTRA) && left != NULLDFSBNO) {
            xfs_btree_reada_bufl(cur->bc_mp, left, 1);
            rval++;
      }

      if ((lr & XFS_BTCUR_RIGHTRA) && right != NULLDFSBNO) {
            xfs_btree_reada_bufl(cur->bc_mp, right, 1);
            rval++;
      }

      return rval;
}

STATIC int
xfs_btree_readahead_sblock(
      struct xfs_btree_cur    *cur,
      int               lr,
      struct xfs_btree_block *block)
{
      int               rval = 0;
      xfs_agblock_t           left = be32_to_cpu(block->bb_u.s.bb_leftsib);
      xfs_agblock_t           right = be32_to_cpu(block->bb_u.s.bb_rightsib);


      if ((lr & XFS_BTCUR_LEFTRA) && left != NULLAGBLOCK) {
            xfs_btree_reada_bufs(cur->bc_mp, cur->bc_private.a.agno,
                             left, 1);
            rval++;
      }

      if ((lr & XFS_BTCUR_RIGHTRA) && right != NULLAGBLOCK) {
            xfs_btree_reada_bufs(cur->bc_mp, cur->bc_private.a.agno,
                             right, 1);
            rval++;
      }

      return rval;
}

/*
 * Read-ahead btree blocks, at the given level.
 * Bits in lr are set from XFS_BTCUR_{LEFT,RIGHT}RA.
 */
STATIC int
xfs_btree_readahead(
      struct xfs_btree_cur    *cur,       /* btree cursor */
      int               lev,        /* level in btree */
      int               lr)         /* left/right bits */
{
      struct xfs_btree_block  *block;

      /*
       * No readahead needed if we are at the root level and the
       * btree root is stored in the inode.
       */
      if ((cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) &&
          (lev == cur->bc_nlevels - 1))
            return 0;

      if ((cur->bc_ra[lev] | lr) == cur->bc_ra[lev])
            return 0;

      cur->bc_ra[lev] |= lr;
      block = XFS_BUF_TO_BLOCK(cur->bc_bufs[lev]);

      if (cur->bc_flags & XFS_BTREE_LONG_PTRS)
            return xfs_btree_readahead_lblock(cur, lr, block);
      return xfs_btree_readahead_sblock(cur, lr, block);
}

/*
 * Set the buffer for level "lev" in the cursor to bp, releasing
 * any previous buffer.
 */
void
xfs_btree_setbuf(
      xfs_btree_cur_t         *cur, /* btree cursor */
      int               lev,  /* level in btree */
      xfs_buf_t         *bp)  /* new buffer to set */
{
      struct xfs_btree_block  *b;   /* btree block */
      xfs_buf_t         *obp; /* old buffer pointer */

      obp = cur->bc_bufs[lev];
      if (obp)
            xfs_trans_brelse(cur->bc_tp, obp);
      cur->bc_bufs[lev] = bp;
      cur->bc_ra[lev] = 0;
      if (!bp)
            return;
      b = XFS_BUF_TO_BLOCK(bp);
      if (cur->bc_flags & XFS_BTREE_LONG_PTRS) {
            if (be64_to_cpu(b->bb_u.l.bb_leftsib) == NULLDFSBNO)
                  cur->bc_ra[lev] |= XFS_BTCUR_LEFTRA;
            if (be64_to_cpu(b->bb_u.l.bb_rightsib) == NULLDFSBNO)
                  cur->bc_ra[lev] |= XFS_BTCUR_RIGHTRA;
      } else {
            if (be32_to_cpu(b->bb_u.s.bb_leftsib) == NULLAGBLOCK)
                  cur->bc_ra[lev] |= XFS_BTCUR_LEFTRA;
            if (be32_to_cpu(b->bb_u.s.bb_rightsib) == NULLAGBLOCK)
                  cur->bc_ra[lev] |= XFS_BTCUR_RIGHTRA;
      }
}

STATIC int
xfs_btree_ptr_is_null(
      struct xfs_btree_cur    *cur,
      union xfs_btree_ptr     *ptr)
{
      if (cur->bc_flags & XFS_BTREE_LONG_PTRS)
            return be64_to_cpu(ptr->l) == NULLDFSBNO;
      else
            return be32_to_cpu(ptr->s) == NULLAGBLOCK;
}

STATIC void
xfs_btree_set_ptr_null(
      struct xfs_btree_cur    *cur,
      union xfs_btree_ptr     *ptr)
{
      if (cur->bc_flags & XFS_BTREE_LONG_PTRS)
            ptr->l = cpu_to_be64(NULLDFSBNO);
      else
            ptr->s = cpu_to_be32(NULLAGBLOCK);
}

/*
 * Get/set/init sibling pointers
 */
STATIC void
xfs_btree_get_sibling(
      struct xfs_btree_cur    *cur,
      struct xfs_btree_block  *block,
      union xfs_btree_ptr     *ptr,
      int               lr)
{
      ASSERT(lr == XFS_BB_LEFTSIB || lr == XFS_BB_RIGHTSIB);

      if (cur->bc_flags & XFS_BTREE_LONG_PTRS) {
            if (lr == XFS_BB_RIGHTSIB)
                  ptr->l = block->bb_u.l.bb_rightsib;
            else
                  ptr->l = block->bb_u.l.bb_leftsib;
      } else {
            if (lr == XFS_BB_RIGHTSIB)
                  ptr->s = block->bb_u.s.bb_rightsib;
            else
                  ptr->s = block->bb_u.s.bb_leftsib;
      }
}

STATIC void
xfs_btree_set_sibling(
      struct xfs_btree_cur    *cur,
      struct xfs_btree_block  *block,
      union xfs_btree_ptr     *ptr,
      int               lr)
{
      ASSERT(lr == XFS_BB_LEFTSIB || lr == XFS_BB_RIGHTSIB);

      if (cur->bc_flags & XFS_BTREE_LONG_PTRS) {
            if (lr == XFS_BB_RIGHTSIB)
                  block->bb_u.l.bb_rightsib = ptr->l;
            else
                  block->bb_u.l.bb_leftsib = ptr->l;
      } else {
            if (lr == XFS_BB_RIGHTSIB)
                  block->bb_u.s.bb_rightsib = ptr->s;
            else
                  block->bb_u.s.bb_leftsib = ptr->s;
      }
}

STATIC void
xfs_btree_init_block(
      struct xfs_btree_cur    *cur,
      int               level,
      int               numrecs,
      struct xfs_btree_block  *new) /* new block */
{
      new->bb_magic = cpu_to_be32(xfs_magics[cur->bc_btnum]);
      new->bb_level = cpu_to_be16(level);
      new->bb_numrecs = cpu_to_be16(numrecs);

      if (cur->bc_flags & XFS_BTREE_LONG_PTRS) {
            new->bb_u.l.bb_leftsib = cpu_to_be64(NULLDFSBNO);
            new->bb_u.l.bb_rightsib = cpu_to_be64(NULLDFSBNO);
      } else {
            new->bb_u.s.bb_leftsib = cpu_to_be32(NULLAGBLOCK);
            new->bb_u.s.bb_rightsib = cpu_to_be32(NULLAGBLOCK);
      }
}

/*
 * Return true if ptr is the last record in the btree and
 * we need to track updateѕ to this record.  The decision
 * will be further refined in the update_lastrec method.
 */
STATIC int
xfs_btree_is_lastrec(
      struct xfs_btree_cur    *cur,
      struct xfs_btree_block  *block,
      int               level)
{
      union xfs_btree_ptr     ptr;

      if (level > 0)
            return 0;
      if (!(cur->bc_flags & XFS_BTREE_LASTREC_UPDATE))
            return 0;

      xfs_btree_get_sibling(cur, block, &ptr, XFS_BB_RIGHTSIB);
      if (!xfs_btree_ptr_is_null(cur, &ptr))
            return 0;
      return 1;
}

STATIC void
xfs_btree_buf_to_ptr(
      struct xfs_btree_cur    *cur,
      struct xfs_buf          *bp,
      union xfs_btree_ptr     *ptr)
{
      if (cur->bc_flags & XFS_BTREE_LONG_PTRS)
            ptr->l = cpu_to_be64(XFS_DADDR_TO_FSB(cur->bc_mp,
                              XFS_BUF_ADDR(bp)));
      else {
            ptr->s = cpu_to_be32(xfs_daddr_to_agbno(cur->bc_mp,
                              XFS_BUF_ADDR(bp)));
      }
}

STATIC xfs_daddr_t
xfs_btree_ptr_to_daddr(
      struct xfs_btree_cur    *cur,
      union xfs_btree_ptr     *ptr)
{
      if (cur->bc_flags & XFS_BTREE_LONG_PTRS) {
            ASSERT(be64_to_cpu(ptr->l) != NULLDFSBNO);

            return XFS_FSB_TO_DADDR(cur->bc_mp, be64_to_cpu(ptr->l));
      } else {
            ASSERT(cur->bc_private.a.agno != NULLAGNUMBER);
            ASSERT(be32_to_cpu(ptr->s) != NULLAGBLOCK);

            return XFS_AGB_TO_DADDR(cur->bc_mp, cur->bc_private.a.agno,
                              be32_to_cpu(ptr->s));
      }
}

STATIC void
xfs_btree_set_refs(
      struct xfs_btree_cur    *cur,
      struct xfs_buf          *bp)
{
      switch (cur->bc_btnum) {
      case XFS_BTNUM_BNO:
      case XFS_BTNUM_CNT:
            XFS_BUF_SET_VTYPE_REF(*bpp, B_FS_MAP, XFS_ALLOC_BTREE_REF);
            break;
      case XFS_BTNUM_INO:
            XFS_BUF_SET_VTYPE_REF(*bpp, B_FS_INOMAP, XFS_INO_BTREE_REF);
            break;
      case XFS_BTNUM_BMAP:
            XFS_BUF_SET_VTYPE_REF(*bpp, B_FS_MAP, XFS_BMAP_BTREE_REF);
            break;
      default:
            ASSERT(0);
      }
}

STATIC int
xfs_btree_get_buf_block(
      struct xfs_btree_cur    *cur,
      union xfs_btree_ptr     *ptr,
      int               flags,
      struct xfs_btree_block  **block,
      struct xfs_buf          **bpp)
{
      struct xfs_mount  *mp = cur->bc_mp;
      xfs_daddr_t       d;

      /* need to sort out how callers deal with failures first */
      ASSERT(!(flags & XFS_BUF_TRYLOCK));

      d = xfs_btree_ptr_to_daddr(cur, ptr);
      *bpp = xfs_trans_get_buf(cur->bc_tp, mp->m_ddev_targp, d,
                         mp->m_bsize, flags);

      ASSERT(*bpp);
      ASSERT(!XFS_BUF_GETERROR(*bpp));

      *block = XFS_BUF_TO_BLOCK(*bpp);
      return 0;
}

/*
 * Read in the buffer at the given ptr and return the buffer and
 * the block pointer within the buffer.
 */
STATIC int
xfs_btree_read_buf_block(
      struct xfs_btree_cur    *cur,
      union xfs_btree_ptr     *ptr,
      int               level,
      int               flags,
      struct xfs_btree_block  **block,
      struct xfs_buf          **bpp)
{
      struct xfs_mount  *mp = cur->bc_mp;
      xfs_daddr_t       d;
      int               error;

      /* need to sort out how callers deal with failures first */
      ASSERT(!(flags & XFS_BUF_TRYLOCK));

      d = xfs_btree_ptr_to_daddr(cur, ptr);
      error = xfs_trans_read_buf(mp, cur->bc_tp, mp->m_ddev_targp, d,
                           mp->m_bsize, flags, bpp);
      if (error)
            return error;

      ASSERT(*bpp != NULL);
      ASSERT(!XFS_BUF_GETERROR(*bpp));

      xfs_btree_set_refs(cur, *bpp);
      *block = XFS_BUF_TO_BLOCK(*bpp);

      error = xfs_btree_check_block(cur, *block, level, *bpp);
      if (error)
            xfs_trans_brelse(cur->bc_tp, *bpp);
      return error;
}

/*
 * Copy keys from one btree block to another.
 */
STATIC void
xfs_btree_copy_keys(
      struct xfs_btree_cur    *cur,
      union xfs_btree_key     *dst_key,
      union xfs_btree_key     *src_key,
      int               numkeys)
{
      ASSERT(numkeys >= 0);
      memcpy(dst_key, src_key, numkeys * cur->bc_ops->key_len);
}

/*
 * Copy records from one btree block to another.
 */
STATIC void
xfs_btree_copy_recs(
      struct xfs_btree_cur    *cur,
      union xfs_btree_rec     *dst_rec,
      union xfs_btree_rec     *src_rec,
      int               numrecs)
{
      ASSERT(numrecs >= 0);
      memcpy(dst_rec, src_rec, numrecs * cur->bc_ops->rec_len);
}

/*
 * Copy block pointers from one btree block to another.
 */
STATIC void
xfs_btree_copy_ptrs(
      struct xfs_btree_cur    *cur,
      union xfs_btree_ptr     *dst_ptr,
      union xfs_btree_ptr     *src_ptr,
      int               numptrs)
{
      ASSERT(numptrs >= 0);
      memcpy(dst_ptr, src_ptr, numptrs * xfs_btree_ptr_len(cur));
}

/*
 * Shift keys one index left/right inside a single btree block.
 */
STATIC void
xfs_btree_shift_keys(
      struct xfs_btree_cur    *cur,
      union xfs_btree_key     *key,
      int               dir,
      int               numkeys)
{
      char              *dst_key;

      ASSERT(numkeys >= 0);
      ASSERT(dir == 1 || dir == -1);

      dst_key = (char *)key + (dir * cur->bc_ops->key_len);
      memmove(dst_key, key, numkeys * cur->bc_ops->key_len);
}

/*
 * Shift records one index left/right inside a single btree block.
 */
STATIC void
xfs_btree_shift_recs(
      struct xfs_btree_cur    *cur,
      union xfs_btree_rec     *rec,
      int               dir,
      int               numrecs)
{
      char              *dst_rec;

      ASSERT(numrecs >= 0);
      ASSERT(dir == 1 || dir == -1);

      dst_rec = (char *)rec + (dir * cur->bc_ops->rec_len);
      memmove(dst_rec, rec, numrecs * cur->bc_ops->rec_len);
}

/*
 * Shift block pointers one index left/right inside a single btree block.
 */
STATIC void
xfs_btree_shift_ptrs(
      struct xfs_btree_cur    *cur,
      union xfs_btree_ptr     *ptr,
      int               dir,
      int               numptrs)
{
      char              *dst_ptr;

      ASSERT(numptrs >= 0);
      ASSERT(dir == 1 || dir == -1);

      dst_ptr = (char *)ptr + (dir * xfs_btree_ptr_len(cur));
      memmove(dst_ptr, ptr, numptrs * xfs_btree_ptr_len(cur));
}

/*
 * Log key values from the btree block.
 */
STATIC void
xfs_btree_log_keys(
      struct xfs_btree_cur    *cur,
      struct xfs_buf          *bp,
      int               first,
      int               last)
{
      XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
      XFS_BTREE_TRACE_ARGBII(cur, bp, first, last);

      if (bp) {
            xfs_trans_log_buf(cur->bc_tp, bp,
                          xfs_btree_key_offset(cur, first),
                          xfs_btree_key_offset(cur, last + 1) - 1);
      } else {
            xfs_trans_log_inode(cur->bc_tp, cur->bc_private.b.ip,
                        xfs_ilog_fbroot(cur->bc_private.b.whichfork));
      }

      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
}

/*
 * Log record values from the btree block.
 */
void
xfs_btree_log_recs(
      struct xfs_btree_cur    *cur,
      struct xfs_buf          *bp,
      int               first,
      int               last)
{
      XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
      XFS_BTREE_TRACE_ARGBII(cur, bp, first, last);

      xfs_trans_log_buf(cur->bc_tp, bp,
                    xfs_btree_rec_offset(cur, first),
                    xfs_btree_rec_offset(cur, last + 1) - 1);

      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
}

/*
 * Log block pointer fields from a btree block (nonleaf).
 */
STATIC void
xfs_btree_log_ptrs(
      struct xfs_btree_cur    *cur, /* btree cursor */
      struct xfs_buf          *bp,  /* buffer containing btree block */
      int               first,      /* index of first pointer to log */
      int               last) /* index of last pointer to log */
{
      XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
      XFS_BTREE_TRACE_ARGBII(cur, bp, first, last);

      if (bp) {
            struct xfs_btree_block  *block = XFS_BUF_TO_BLOCK(bp);
            int               level = xfs_btree_get_level(block);

            xfs_trans_log_buf(cur->bc_tp, bp,
                        xfs_btree_ptr_offset(cur, first, level),
                        xfs_btree_ptr_offset(cur, last + 1, level) - 1);
      } else {
            xfs_trans_log_inode(cur->bc_tp, cur->bc_private.b.ip,
                  xfs_ilog_fbroot(cur->bc_private.b.whichfork));
      }

      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
}

/*
 * Log fields from a btree block header.
 */
void
xfs_btree_log_block(
      struct xfs_btree_cur    *cur, /* btree cursor */
      struct xfs_buf          *bp,  /* buffer containing btree block */
      int               fields)     /* mask of fields: XFS_BB_... */
{
      int               first;      /* first byte offset logged */
      int               last; /* last byte offset logged */
      static const short      soffsets[] = {    /* table of offsets (short) */
            offsetof(struct xfs_btree_block, bb_magic),
            offsetof(struct xfs_btree_block, bb_level),
            offsetof(struct xfs_btree_block, bb_numrecs),
            offsetof(struct xfs_btree_block, bb_u.s.bb_leftsib),
            offsetof(struct xfs_btree_block, bb_u.s.bb_rightsib),
            XFS_BTREE_SBLOCK_LEN
      };
      static const short      loffsets[] = {    /* table of offsets (long) */
            offsetof(struct xfs_btree_block, bb_magic),
            offsetof(struct xfs_btree_block, bb_level),
            offsetof(struct xfs_btree_block, bb_numrecs),
            offsetof(struct xfs_btree_block, bb_u.l.bb_leftsib),
            offsetof(struct xfs_btree_block, bb_u.l.bb_rightsib),
            XFS_BTREE_LBLOCK_LEN
      };

      XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
      XFS_BTREE_TRACE_ARGBI(cur, bp, fields);

      if (bp) {
            xfs_btree_offsets(fields,
                          (cur->bc_flags & XFS_BTREE_LONG_PTRS) ?
                              loffsets : soffsets,
                          XFS_BB_NUM_BITS, &first, &last);
            xfs_trans_log_buf(cur->bc_tp, bp, first, last);
      } else {
            xfs_trans_log_inode(cur->bc_tp, cur->bc_private.b.ip,
                  xfs_ilog_fbroot(cur->bc_private.b.whichfork));
      }

      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
}

/*
 * Increment cursor by one record at the level.
 * For nonzero levels the leaf-ward information is untouched.
 */
int                                 /* error */
xfs_btree_increment(
      struct xfs_btree_cur    *cur,
      int               level,
      int               *stat)            /* success/failure */
{
      struct xfs_btree_block  *block;
      union xfs_btree_ptr     ptr;
      struct xfs_buf          *bp;
      int               error;            /* error return value */
      int               lev;

      XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
      XFS_BTREE_TRACE_ARGI(cur, level);

      ASSERT(level < cur->bc_nlevels);

      /* Read-ahead to the right at this level. */
      xfs_btree_readahead(cur, level, XFS_BTCUR_RIGHTRA);

      /* Get a pointer to the btree block. */
      block = xfs_btree_get_block(cur, level, &bp);

#ifdef DEBUG
      error = xfs_btree_check_block(cur, block, level, bp);
      if (error)
            goto error0;
#endif

      /* We're done if we remain in the block after the increment. */
      if (++cur->bc_ptrs[level] <= xfs_btree_get_numrecs(block))
            goto out1;

      /* Fail if we just went off the right edge of the tree. */
      xfs_btree_get_sibling(cur, block, &ptr, XFS_BB_RIGHTSIB);
      if (xfs_btree_ptr_is_null(cur, &ptr))
            goto out0;

      XFS_BTREE_STATS_INC(cur, increment);

      /*
       * March up the tree incrementing pointers.
       * Stop when we don't go off the right edge of a block.
       */
      for (lev = level + 1; lev < cur->bc_nlevels; lev++) {
            block = xfs_btree_get_block(cur, lev, &bp);

#ifdef DEBUG
            error = xfs_btree_check_block(cur, block, lev, bp);
            if (error)
                  goto error0;
#endif

            if (++cur->bc_ptrs[lev] <= xfs_btree_get_numrecs(block))
                  break;

            /* Read-ahead the right block for the next loop. */
            xfs_btree_readahead(cur, lev, XFS_BTCUR_RIGHTRA);
      }

      /*
       * If we went off the root then we are either seriously
       * confused or have the tree root in an inode.
       */
      if (lev == cur->bc_nlevels) {
            if (cur->bc_flags & XFS_BTREE_ROOT_IN_INODE)
                  goto out0;
            ASSERT(0);
            error = EFSCORRUPTED;
            goto error0;
      }
      ASSERT(lev < cur->bc_nlevels);

      /*
       * Now walk back down the tree, fixing up the cursor's buffer
       * pointers and key numbers.
       */
      for (block = xfs_btree_get_block(cur, lev, &bp); lev > level; ) {
            union xfs_btree_ptr     *ptrp;

            ptrp = xfs_btree_ptr_addr(cur, cur->bc_ptrs[lev], block);
            error = xfs_btree_read_buf_block(cur, ptrp, --lev,
                                          0, &block, &bp);
            if (error)
                  goto error0;

            xfs_btree_setbuf(cur, lev, bp);
            cur->bc_ptrs[lev] = 1;
      }
out1:
      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
      *stat = 1;
      return 0;

out0:
      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
      *stat = 0;
      return 0;

error0:
      XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
      return error;
}

/*
 * Decrement cursor by one record at the level.
 * For nonzero levels the leaf-ward information is untouched.
 */
int                                 /* error */
xfs_btree_decrement(
      struct xfs_btree_cur    *cur,
      int               level,
      int               *stat)            /* success/failure */
{
      struct xfs_btree_block  *block;
      xfs_buf_t         *bp;
      int               error;            /* error return value */
      int               lev;
      union xfs_btree_ptr     ptr;

      XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
      XFS_BTREE_TRACE_ARGI(cur, level);

      ASSERT(level < cur->bc_nlevels);

      /* Read-ahead to the left at this level. */
      xfs_btree_readahead(cur, level, XFS_BTCUR_LEFTRA);

      /* We're done if we remain in the block after the decrement. */
      if (--cur->bc_ptrs[level] > 0)
            goto out1;

      /* Get a pointer to the btree block. */
      block = xfs_btree_get_block(cur, level, &bp);

#ifdef DEBUG
      error = xfs_btree_check_block(cur, block, level, bp);
      if (error)
            goto error0;
#endif

      /* Fail if we just went off the left edge of the tree. */
      xfs_btree_get_sibling(cur, block, &ptr, XFS_BB_LEFTSIB);
      if (xfs_btree_ptr_is_null(cur, &ptr))
            goto out0;

      XFS_BTREE_STATS_INC(cur, decrement);

      /*
       * March up the tree decrementing pointers.
       * Stop when we don't go off the left edge of a block.
       */
      for (lev = level + 1; lev < cur->bc_nlevels; lev++) {
            if (--cur->bc_ptrs[lev] > 0)
                  break;
            /* Read-ahead the left block for the next loop. */
            xfs_btree_readahead(cur, lev, XFS_BTCUR_LEFTRA);
      }

      /*
       * If we went off the root then we are seriously confused.
       * or the root of the tree is in an inode.
       */
      if (lev == cur->bc_nlevels) {
            if (cur->bc_flags & XFS_BTREE_ROOT_IN_INODE)
                  goto out0;
            ASSERT(0);
            error = EFSCORRUPTED;
            goto error0;
      }
      ASSERT(lev < cur->bc_nlevels);

      /*
       * Now walk back down the tree, fixing up the cursor's buffer
       * pointers and key numbers.
       */
      for (block = xfs_btree_get_block(cur, lev, &bp); lev > level; ) {
            union xfs_btree_ptr     *ptrp;

            ptrp = xfs_btree_ptr_addr(cur, cur->bc_ptrs[lev], block);
            error = xfs_btree_read_buf_block(cur, ptrp, --lev,
                                          0, &block, &bp);
            if (error)
                  goto error0;
            xfs_btree_setbuf(cur, lev, bp);
            cur->bc_ptrs[lev] = xfs_btree_get_numrecs(block);
      }
out1:
      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
      *stat = 1;
      return 0;

out0:
      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
      *stat = 0;
      return 0;

error0:
      XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
      return error;
}

STATIC int
xfs_btree_lookup_get_block(
      struct xfs_btree_cur    *cur, /* btree cursor */
      int               level,      /* level in the btree */
      union xfs_btree_ptr     *pp,  /* ptr to btree block */
      struct xfs_btree_block  **blkp) /* return btree block */
{
      struct xfs_buf          *bp;  /* buffer pointer for btree block */
      int               error = 0;

      /* special case the root block if in an inode */
      if ((cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) &&
          (level == cur->bc_nlevels - 1)) {
            *blkp = xfs_btree_get_iroot(cur);
            return 0;
      }

      /*
       * If the old buffer at this level for the disk address we are
       * looking for re-use it.
       *
       * Otherwise throw it away and get a new one.
       */
      bp = cur->bc_bufs[level];
      if (bp && XFS_BUF_ADDR(bp) == xfs_btree_ptr_to_daddr(cur, pp)) {
            *blkp = XFS_BUF_TO_BLOCK(bp);
            return 0;
      }

      error = xfs_btree_read_buf_block(cur, pp, level, 0, blkp, &bp);
      if (error)
            return error;

      xfs_btree_setbuf(cur, level, bp);
      return 0;
}

/*
 * Get current search key.  For level 0 we don't actually have a key
 * structure so we make one up from the record.  For all other levels
 * we just return the right key.
 */
STATIC union xfs_btree_key *
xfs_lookup_get_search_key(
      struct xfs_btree_cur    *cur,
      int               level,
      int               keyno,
      struct xfs_btree_block  *block,
      union xfs_btree_key     *kp)
{
      if (level == 0) {
            cur->bc_ops->init_key_from_rec(kp,
                        xfs_btree_rec_addr(cur, keyno, block));
            return kp;
      }

      return xfs_btree_key_addr(cur, keyno, block);
}

/*
 * Lookup the record.  The cursor is made to point to it, based on dir.
 * Return 0 if can't find any such record, 1 for success.
 */
int                           /* error */
xfs_btree_lookup(
      struct xfs_btree_cur    *cur, /* btree cursor */
      xfs_lookup_t            dir,  /* <=, ==, or >= */
      int               *stat)      /* success/failure */
{
      struct xfs_btree_block  *block;     /* current btree block */
      __int64_t         diff; /* difference for the current key */
      int               error;      /* error return value */
      int               keyno;      /* current key number */
      int               level;      /* level in the btree */
      union xfs_btree_ptr     *pp;  /* ptr to btree block */
      union xfs_btree_ptr     ptr;  /* ptr to btree block */

      XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
      XFS_BTREE_TRACE_ARGI(cur, dir);

      XFS_BTREE_STATS_INC(cur, lookup);

      block = NULL;
      keyno = 0;

      /* initialise start pointer from cursor */
      cur->bc_ops->init_ptr_from_cur(cur, &ptr);
      pp = &ptr;

      /*
       * Iterate over each level in the btree, starting at the root.
       * For each level above the leaves, find the key we need, based
       * on the lookup record, then follow the corresponding block
       * pointer down to the next level.
       */
      for (level = cur->bc_nlevels - 1, diff = 1; level >= 0; level--) {
            /* Get the block we need to do the lookup on. */
            error = xfs_btree_lookup_get_block(cur, level, pp, &block);
            if (error)
                  goto error0;

            if (diff == 0) {
                  /*
                   * If we already had a key match at a higher level, we
                   * know we need to use the first entry in this block.
                   */
                  keyno = 1;
            } else {
                  /* Otherwise search this block. Do a binary search. */

                  int   high; /* high entry number */
                  int   low;  /* low entry number */

                  /* Set low and high entry numbers, 1-based. */
                  low = 1;
                  high = xfs_btree_get_numrecs(block);
                  if (!high) {
                        /* Block is empty, must be an empty leaf. */
                        ASSERT(level == 0 && cur->bc_nlevels == 1);

                        cur->bc_ptrs[0] = dir != XFS_LOOKUP_LE;
                        XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
                        *stat = 0;
                        return 0;
                  }

                  /* Binary search the block. */
                  while (low <= high) {
                        union xfs_btree_key     key;
                        union xfs_btree_key     *kp;

                        XFS_BTREE_STATS_INC(cur, compare);

                        /* keyno is average of low and high. */
                        keyno = (low + high) >> 1;

                        /* Get current search key */
                        kp = xfs_lookup_get_search_key(cur, level,
                                    keyno, block, &key);

                        /*
                         * Compute difference to get next direction:
                         *  - less than, move right
                         *  - greater than, move left
                         *  - equal, we're done
                         */
                        diff = cur->bc_ops->key_diff(cur, kp);
                        if (diff < 0)
                              low = keyno + 1;
                        else if (diff > 0)
                              high = keyno - 1;
                        else
                              break;
                  }
            }

            /*
             * If there are more levels, set up for the next level
             * by getting the block number and filling in the cursor.
             */
            if (level > 0) {
                  /*
                   * If we moved left, need the previous key number,
                   * unless there isn't one.
                   */
                  if (diff > 0 && --keyno < 1)
                        keyno = 1;
                  pp = xfs_btree_ptr_addr(cur, keyno, block);

#ifdef DEBUG
                  error = xfs_btree_check_ptr(cur, pp, 0, level);
                  if (error)
                        goto error0;
#endif
                  cur->bc_ptrs[level] = keyno;
            }
      }

      /* Done with the search. See if we need to adjust the results. */
      if (dir != XFS_LOOKUP_LE && diff < 0) {
            keyno++;
            /*
             * If ge search and we went off the end of the block, but it's
             * not the last block, we're in the wrong block.
             */
            xfs_btree_get_sibling(cur, block, &ptr, XFS_BB_RIGHTSIB);
            if (dir == XFS_LOOKUP_GE &&
                keyno > xfs_btree_get_numrecs(block) &&
                !xfs_btree_ptr_is_null(cur, &ptr)) {
                  int   i;

                  cur->bc_ptrs[0] = keyno;
                  error = xfs_btree_increment(cur, 0, &i);
                  if (error)
                        goto error0;
                  XFS_WANT_CORRUPTED_RETURN(i == 1);
                  XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
                  *stat = 1;
                  return 0;
            }
      } else if (dir == XFS_LOOKUP_LE && diff > 0)
            keyno--;
      cur->bc_ptrs[0] = keyno;

      /* Return if we succeeded or not. */
      if (keyno == 0 || keyno > xfs_btree_get_numrecs(block))
            *stat = 0;
      else if (dir != XFS_LOOKUP_EQ || diff == 0)
            *stat = 1;
      else
            *stat = 0;
      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
      return 0;

error0:
      XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
      return error;
}

/*
 * Update keys at all levels from here to the root along the cursor's path.
 */
STATIC int
xfs_btree_updkey(
      struct xfs_btree_cur    *cur,
      union xfs_btree_key     *keyp,
      int               level)
{
      struct xfs_btree_block  *block;
      struct xfs_buf          *bp;
      union xfs_btree_key     *kp;
      int               ptr;

      XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
      XFS_BTREE_TRACE_ARGIK(cur, level, keyp);

      ASSERT(!(cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) || level >= 1);

      /*
       * Go up the tree from this level toward the root.
       * At each level, update the key value to the value input.
       * Stop when we reach a level where the cursor isn't pointing
       * at the first entry in the block.
       */
      for (ptr = 1; ptr == 1 && level < cur->bc_nlevels; level++) {
#ifdef DEBUG
            int         error;
#endif
            block = xfs_btree_get_block(cur, level, &bp);
#ifdef DEBUG
            error = xfs_btree_check_block(cur, block, level, bp);
            if (error) {
                  XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
                  return error;
            }
#endif
            ptr = cur->bc_ptrs[level];
            kp = xfs_btree_key_addr(cur, ptr, block);
            xfs_btree_copy_keys(cur, kp, keyp, 1);
            xfs_btree_log_keys(cur, bp, ptr, ptr);
      }

      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
      return 0;
}

/*
 * Update the record referred to by cur to the value in the
 * given record. This either works (return 0) or gets an
 * EFSCORRUPTED error.
 */
int
xfs_btree_update(
      struct xfs_btree_cur    *cur,
      union xfs_btree_rec     *rec)
{
      struct xfs_btree_block  *block;
      struct xfs_buf          *bp;
      int               error;
      int               ptr;
      union xfs_btree_rec     *rp;

      XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
      XFS_BTREE_TRACE_ARGR(cur, rec);

      /* Pick up the current block. */
      block = xfs_btree_get_block(cur, 0, &bp);

#ifdef DEBUG
      error = xfs_btree_check_block(cur, block, 0, bp);
      if (error)
            goto error0;
#endif
      /* Get the address of the rec to be updated. */
      ptr = cur->bc_ptrs[0];
      rp = xfs_btree_rec_addr(cur, ptr, block);

      /* Fill in the new contents and log them. */
      xfs_btree_copy_recs(cur, rp, rec, 1);
      xfs_btree_log_recs(cur, bp, ptr, ptr);

      /*
       * If we are tracking the last record in the tree and
       * we are at the far right edge of the tree, update it.
       */
      if (xfs_btree_is_lastrec(cur, block, 0)) {
            cur->bc_ops->update_lastrec(cur, block, rec,
                                  ptr, LASTREC_UPDATE);
      }

      /* Updating first rec in leaf. Pass new key value up to our parent. */
      if (ptr == 1) {
            union xfs_btree_key     key;

            cur->bc_ops->init_key_from_rec(&key, rec);
            error = xfs_btree_updkey(cur, &key, 1);
            if (error)
                  goto error0;
      }

      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
      return 0;

error0:
      XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
      return error;
}

/*
 * Move 1 record left from cur/level if possible.
 * Update cur to reflect the new path.
 */
STATIC int                          /* error */
xfs_btree_lshift(
      struct xfs_btree_cur    *cur,
      int               level,
      int               *stat)            /* success/failure */
{
      union xfs_btree_key     key;        /* btree key */
      struct xfs_buf          *lbp;       /* left buffer pointer */
      struct xfs_btree_block  *left;            /* left btree block */
      int               lrecs;            /* left record count */
      struct xfs_buf          *rbp;       /* right buffer pointer */
      struct xfs_btree_block  *right;           /* right btree block */
      int               rrecs;            /* right record count */
      union xfs_btree_ptr     lptr;       /* left btree pointer */
      union xfs_btree_key     *rkp = NULL;      /* right btree key */
      union xfs_btree_ptr     *rpp = NULL;      /* right address pointer */
      union xfs_btree_rec     *rrp = NULL;      /* right record pointer */
      int               error;            /* error return value */

      XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
      XFS_BTREE_TRACE_ARGI(cur, level);

      if ((cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) &&
          level == cur->bc_nlevels - 1)
            goto out0;

      /* Set up variables for this block as "right". */
      right = xfs_btree_get_block(cur, level, &rbp);

#ifdef DEBUG
      error = xfs_btree_check_block(cur, right, level, rbp);
      if (error)
            goto error0;
#endif

      /* If we've got no left sibling then we can't shift an entry left. */
      xfs_btree_get_sibling(cur, right, &lptr, XFS_BB_LEFTSIB);
      if (xfs_btree_ptr_is_null(cur, &lptr))
            goto out0;

      /*
       * If the cursor entry is the one that would be moved, don't
       * do it... it's too complicated.
       */
      if (cur->bc_ptrs[level] <= 1)
            goto out0;

      /* Set up the left neighbor as "left". */
      error = xfs_btree_read_buf_block(cur, &lptr, level, 0, &left, &lbp);
      if (error)
            goto error0;

      /* If it's full, it can't take another entry. */
      lrecs = xfs_btree_get_numrecs(left);
      if (lrecs == cur->bc_ops->get_maxrecs(cur, level))
            goto out0;

      rrecs = xfs_btree_get_numrecs(right);

      /*
       * We add one entry to the left side and remove one for the right side.
       * Account for it here, the changes will be updated on disk and logged
       * later.
       */
      lrecs++;
      rrecs--;

      XFS_BTREE_STATS_INC(cur, lshift);
      XFS_BTREE_STATS_ADD(cur, moves, 1);

      /*
       * If non-leaf, copy a key and a ptr to the left block.
       * Log the changes to the left block.
       */
      if (level > 0) {
            /* It's a non-leaf.  Move keys and pointers. */
            union xfs_btree_key     *lkp; /* left btree key */
            union xfs_btree_ptr     *lpp; /* left address pointer */

            lkp = xfs_btree_key_addr(cur, lrecs, left);
            rkp = xfs_btree_key_addr(cur, 1, right);

            lpp = xfs_btree_ptr_addr(cur, lrecs, left);
            rpp = xfs_btree_ptr_addr(cur, 1, right);
#ifdef DEBUG
            error = xfs_btree_check_ptr(cur, rpp, 0, level);
            if (error)
                  goto error0;
#endif
            xfs_btree_copy_keys(cur, lkp, rkp, 1);
            xfs_btree_copy_ptrs(cur, lpp, rpp, 1);

            xfs_btree_log_keys(cur, lbp, lrecs, lrecs);
            xfs_btree_log_ptrs(cur, lbp, lrecs, lrecs);

            ASSERT(cur->bc_ops->keys_inorder(cur,
                  xfs_btree_key_addr(cur, lrecs - 1, left), lkp));
      } else {
            /* It's a leaf.  Move records.  */
            union xfs_btree_rec     *lrp; /* left record pointer */

            lrp = xfs_btree_rec_addr(cur, lrecs, left);
            rrp = xfs_btree_rec_addr(cur, 1, right);

            xfs_btree_copy_recs(cur, lrp, rrp, 1);
            xfs_btree_log_recs(cur, lbp, lrecs, lrecs);

            ASSERT(cur->bc_ops->recs_inorder(cur,
                  xfs_btree_rec_addr(cur, lrecs - 1, left), lrp));
      }

      xfs_btree_set_numrecs(left, lrecs);
      xfs_btree_log_block(cur, lbp, XFS_BB_NUMRECS);

      xfs_btree_set_numrecs(right, rrecs);
      xfs_btree_log_block(cur, rbp, XFS_BB_NUMRECS);

      /*
       * Slide the contents of right down one entry.
       */
      XFS_BTREE_STATS_ADD(cur, moves, rrecs - 1);
      if (level > 0) {
            /* It's a nonleaf. operate on keys and ptrs */
#ifdef DEBUG
            int               i;          /* loop index */

            for (i = 0; i < rrecs; i++) {
                  error = xfs_btree_check_ptr(cur, rpp, i + 1, level);
                  if (error)
                        goto error0;
            }
#endif
            xfs_btree_shift_keys(cur,
                        xfs_btree_key_addr(cur, 2, right),
                        -1, rrecs);
            xfs_btree_shift_ptrs(cur,
                        xfs_btree_ptr_addr(cur, 2, right),
                        -1, rrecs);

            xfs_btree_log_keys(cur, rbp, 1, rrecs);
            xfs_btree_log_ptrs(cur, rbp, 1, rrecs);
      } else {
            /* It's a leaf. operate on records */
            xfs_btree_shift_recs(cur,
                  xfs_btree_rec_addr(cur, 2, right),
                  -1, rrecs);
            xfs_btree_log_recs(cur, rbp, 1, rrecs);

            /*
             * If it's the first record in the block, we'll need a key
             * structure to pass up to the next level (updkey).
             */
            cur->bc_ops->init_key_from_rec(&key,
                  xfs_btree_rec_addr(cur, 1, right));
            rkp = &key;
      }

      /* Update the parent key values of right. */
      error = xfs_btree_updkey(cur, rkp, level + 1);
      if (error)
            goto error0;

      /* Slide the cursor value left one. */
      cur->bc_ptrs[level]--;

      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
      *stat = 1;
      return 0;

out0:
      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
      *stat = 0;
      return 0;

error0:
      XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
      return error;
}

/*
 * Move 1 record right from cur/level if possible.
 * Update cur to reflect the new path.
 */
STATIC int                          /* error */
xfs_btree_rshift(
      struct xfs_btree_cur    *cur,
      int               level,
      int               *stat)            /* success/failure */
{
      union xfs_btree_key     key;        /* btree key */
      struct xfs_buf          *lbp;       /* left buffer pointer */
      struct xfs_btree_block  *left;            /* left btree block */
      struct xfs_buf          *rbp;       /* right buffer pointer */
      struct xfs_btree_block  *right;           /* right btree block */
      struct xfs_btree_cur    *tcur;            /* temporary btree cursor */
      union xfs_btree_ptr     rptr;       /* right block pointer */
      union xfs_btree_key     *rkp;       /* right btree key */
      int               rrecs;            /* right record count */
      int               lrecs;            /* left record count */
      int               error;            /* error return value */
      int               i;          /* loop counter */

      XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
      XFS_BTREE_TRACE_ARGI(cur, level);

      if ((cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) &&
          (level == cur->bc_nlevels - 1))
            goto out0;

      /* Set up variables for this block as "left". */
      left = xfs_btree_get_block(cur, level, &lbp);

#ifdef DEBUG
      error = xfs_btree_check_block(cur, left, level, lbp);
      if (error)
            goto error0;
#endif

      /* If we've got no right sibling then we can't shift an entry right. */
      xfs_btree_get_sibling(cur, left, &rptr, XFS_BB_RIGHTSIB);
      if (xfs_btree_ptr_is_null(cur, &rptr))
            goto out0;

      /*
       * If the cursor entry is the one that would be moved, don't
       * do it... it's too complicated.
       */
      lrecs = xfs_btree_get_numrecs(left);
      if (cur->bc_ptrs[level] >= lrecs)
            goto out0;

      /* Set up the right neighbor as "right". */
      error = xfs_btree_read_buf_block(cur, &rptr, level, 0, &right, &rbp);
      if (error)
            goto error0;

      /* If it's full, it can't take another entry. */
      rrecs = xfs_btree_get_numrecs(right);
      if (rrecs == cur->bc_ops->get_maxrecs(cur, level))
            goto out0;

      XFS_BTREE_STATS_INC(cur, rshift);
      XFS_BTREE_STATS_ADD(cur, moves, rrecs);

      /*
       * Make a hole at the start of the right neighbor block, then
       * copy the last left block entry to the hole.
       */
      if (level > 0) {
            /* It's a nonleaf. make a hole in the keys and ptrs */
            union xfs_btree_key     *lkp;
            union xfs_btree_ptr     *lpp;
            union xfs_btree_ptr     *rpp;

            lkp = xfs_btree_key_addr(cur, lrecs, left);
            lpp = xfs_btree_ptr_addr(cur, lrecs, left);
            rkp = xfs_btree_key_addr(cur, 1, right);
            rpp = xfs_btree_ptr_addr(cur, 1, right);

#ifdef DEBUG
            for (i = rrecs - 1; i >= 0; i--) {
                  error = xfs_btree_check_ptr(cur, rpp, i, level);
                  if (error)
                        goto error0;
            }
#endif

            xfs_btree_shift_keys(cur, rkp, 1, rrecs);
            xfs_btree_shift_ptrs(cur, rpp, 1, rrecs);

#ifdef DEBUG
            error = xfs_btree_check_ptr(cur, lpp, 0, level);
            if (error)
                  goto error0;
#endif

            /* Now put the new data in, and log it. */
            xfs_btree_copy_keys(cur, rkp, lkp, 1);
            xfs_btree_copy_ptrs(cur, rpp, lpp, 1);

            xfs_btree_log_keys(cur, rbp, 1, rrecs + 1);
            xfs_btree_log_ptrs(cur, rbp, 1, rrecs + 1);

            ASSERT(cur->bc_ops->keys_inorder(cur, rkp,
                  xfs_btree_key_addr(cur, 2, right)));
      } else {
            /* It's a leaf. make a hole in the records */
            union xfs_btree_rec     *lrp;
            union xfs_btree_rec     *rrp;

            lrp = xfs_btree_rec_addr(cur, lrecs, left);
            rrp = xfs_btree_rec_addr(cur, 1, right);

            xfs_btree_shift_recs(cur, rrp, 1, rrecs);

            /* Now put the new data in, and log it. */
            xfs_btree_copy_recs(cur, rrp, lrp, 1);
            xfs_btree_log_recs(cur, rbp, 1, rrecs + 1);

            cur->bc_ops->init_key_from_rec(&key, rrp);
            rkp = &key;

            ASSERT(cur->bc_ops->recs_inorder(cur, rrp,
                  xfs_btree_rec_addr(cur, 2, right)));
      }

      /*
       * Decrement and log left's numrecs, bump and log right's numrecs.
       */
      xfs_btree_set_numrecs(left, --lrecs);
      xfs_btree_log_block(cur, lbp, XFS_BB_NUMRECS);

      xfs_btree_set_numrecs(right, ++rrecs);
      xfs_btree_log_block(cur, rbp, XFS_BB_NUMRECS);

      /*
       * Using a temporary cursor, update the parent key values of the
       * block on the right.
       */
      error = xfs_btree_dup_cursor(cur, &tcur);
      if (error)
            goto error0;
      i = xfs_btree_lastrec(tcur, level);
      XFS_WANT_CORRUPTED_GOTO(i == 1, error0);

      error = xfs_btree_increment(tcur, level, &i);
      if (error)
            goto error1;

      error = xfs_btree_updkey(tcur, rkp, level + 1);
      if (error)
            goto error1;

      xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);

      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
      *stat = 1;
      return 0;

out0:
      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
      *stat = 0;
      return 0;

error0:
      XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
      return error;

error1:
      XFS_BTREE_TRACE_CURSOR(tcur, XBT_ERROR);
      xfs_btree_del_cursor(tcur, XFS_BTREE_ERROR);
      return error;
}

/*
 * Split cur/level block in half.
 * Return new block number and the key to its first
 * record (to be inserted into parent).
 */
STATIC int                          /* error */
xfs_btree_split(
      struct xfs_btree_cur    *cur,
      int               level,
      union xfs_btree_ptr     *ptrp,
      union xfs_btree_key     *key,
      struct xfs_btree_cur    **curp,
      int               *stat)            /* success/failure */
{
      union xfs_btree_ptr     lptr;       /* left sibling block ptr */
      struct xfs_buf          *lbp;       /* left buffer pointer */
      struct xfs_btree_block  *left;            /* left btree block */
      union xfs_btree_ptr     rptr;       /* right sibling block ptr */
      struct xfs_buf          *rbp;       /* right buffer pointer */
      struct xfs_btree_block  *right;           /* right btree block */
      union xfs_btree_ptr     rrptr;            /* right-right sibling ptr */
      struct xfs_buf          *rrbp;            /* right-right buffer pointer */
      struct xfs_btree_block  *rrblock;   /* right-right btree block */
      int               lrecs;
      int               rrecs;
      int               src_index;
      int               error;            /* error return value */
#ifdef DEBUG
      int               i;
#endif

      XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
      XFS_BTREE_TRACE_ARGIPK(cur, level, *ptrp, key);

      XFS_BTREE_STATS_INC(cur, split);

      /* Set up left block (current one). */
      left = xfs_btree_get_block(cur, level, &lbp);

#ifdef DEBUG
      error = xfs_btree_check_block(cur, left, level, lbp);
      if (error)
            goto error0;
#endif

      xfs_btree_buf_to_ptr(cur, lbp, &lptr);

      /* Allocate the new block. If we can't do it, we're toast. Give up. */
      error = cur->bc_ops->alloc_block(cur, &lptr, &rptr, 1, stat);
      if (error)
            goto error0;
      if (*stat == 0)
            goto out0;
      XFS_BTREE_STATS_INC(cur, alloc);

      /* Set up the new block as "right". */
      error = xfs_btree_get_buf_block(cur, &rptr, 0, &right, &rbp);
      if (error)
            goto error0;

      /* Fill in the btree header for the new right block. */
      xfs_btree_init_block(cur, xfs_btree_get_level(left), 0, right);

      /*
       * Split the entries between the old and the new block evenly.
       * Make sure that if there's an odd number of entries now, that
       * each new block will have the same number of entries.
       */
      lrecs = xfs_btree_get_numrecs(left);
      rrecs = lrecs / 2;
      if ((lrecs & 1) && cur->bc_ptrs[level] <= rrecs + 1)
            rrecs++;
      src_index = (lrecs - rrecs + 1);

      XFS_BTREE_STATS_ADD(cur, moves, rrecs);

      /*
       * Copy btree block entries from the left block over to the
       * new block, the right. Update the right block and log the
       * changes.
       */
      if (level > 0) {
            /* It's a non-leaf.  Move keys and pointers. */
            union xfs_btree_key     *lkp; /* left btree key */
            union xfs_btree_ptr     *lpp; /* left address pointer */
            union xfs_btree_key     *rkp; /* right btree key */
            union xfs_btree_ptr     *rpp; /* right address pointer */

            lkp = xfs_btree_key_addr(cur, src_index, left);
            lpp = xfs_btree_ptr_addr(cur, src_index, left);
            rkp = xfs_btree_key_addr(cur, 1, right);
            rpp = xfs_btree_ptr_addr(cur, 1, right);

#ifdef DEBUG
            for (i = src_index; i < rrecs; i++) {
                  error = xfs_btree_check_ptr(cur, lpp, i, level);
                  if (error)
                        goto error0;
            }
#endif

            xfs_btree_copy_keys(cur, rkp, lkp, rrecs);
            xfs_btree_copy_ptrs(cur, rpp, lpp, rrecs);

            xfs_btree_log_keys(cur, rbp, 1, rrecs);
            xfs_btree_log_ptrs(cur, rbp, 1, rrecs);

            /* Grab the keys to the entries moved to the right block */
            xfs_btree_copy_keys(cur, key, rkp, 1);
      } else {
            /* It's a leaf.  Move records.  */
            union xfs_btree_rec     *lrp; /* left record pointer */
            union xfs_btree_rec     *rrp; /* right record pointer */

            lrp = xfs_btree_rec_addr(cur, src_index, left);
            rrp = xfs_btree_rec_addr(cur, 1, right);

            xfs_btree_copy_recs(cur, rrp, lrp, rrecs);
            xfs_btree_log_recs(cur, rbp, 1, rrecs);

            cur->bc_ops->init_key_from_rec(key,
                  xfs_btree_rec_addr(cur, 1, right));
      }


      /*
       * Find the left block number by looking in the buffer.
       * Adjust numrecs, sibling pointers.
       */
      xfs_btree_get_sibling(cur, left, &rrptr, XFS_BB_RIGHTSIB);
      xfs_btree_set_sibling(cur, right, &rrptr, XFS_BB_RIGHTSIB);
      xfs_btree_set_sibling(cur, right, &lptr, XFS_BB_LEFTSIB);
      xfs_btree_set_sibling(cur, left, &rptr, XFS_BB_RIGHTSIB);

      lrecs -= rrecs;
      xfs_btree_set_numrecs(left, lrecs);
      xfs_btree_set_numrecs(right, xfs_btree_get_numrecs(right) + rrecs);

      xfs_btree_log_block(cur, rbp, XFS_BB_ALL_BITS);
      xfs_btree_log_block(cur, lbp, XFS_BB_NUMRECS | XFS_BB_RIGHTSIB);

      /*
       * If there's a block to the new block's right, make that block
       * point back to right instead of to left.
       */
      if (!xfs_btree_ptr_is_null(cur, &rrptr)) {
            error = xfs_btree_read_buf_block(cur, &rrptr, level,
                                          0, &rrblock, &rrbp);
            if (error)
                  goto error0;
            xfs_btree_set_sibling(cur, rrblock, &rptr, XFS_BB_LEFTSIB);
            xfs_btree_log_block(cur, rrbp, XFS_BB_LEFTSIB);
      }
      /*
       * If the cursor is really in the right block, move it there.
       * If it's just pointing past the last entry in left, then we'll
       * insert there, so don't change anything in that case.
       */
      if (cur->bc_ptrs[level] > lrecs + 1) {
            xfs_btree_setbuf(cur, level, rbp);
            cur->bc_ptrs[level] -= lrecs;
      }
      /*
       * If there are more levels, we'll need another cursor which refers
       * the right block, no matter where this cursor was.
       */
      if (level + 1 < cur->bc_nlevels) {
            error = xfs_btree_dup_cursor(cur, curp);
            if (error)
                  goto error0;
            (*curp)->bc_ptrs[level + 1]++;
      }
      *ptrp = rptr;
      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
      *stat = 1;
      return 0;
out0:
      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
      *stat = 0;
      return 0;

error0:
      XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
      return error;
}

/*
 * Copy the old inode root contents into a real block and make the
 * broot point to it.
 */
int                                 /* error */
xfs_btree_new_iroot(
      struct xfs_btree_cur    *cur,       /* btree cursor */
      int               *logflags,  /* logging flags for inode */
      int               *stat)            /* return status - 0 fail */
{
      struct xfs_buf          *cbp;       /* buffer for cblock */
      struct xfs_btree_block  *block;           /* btree block */
      struct xfs_btree_block  *cblock;    /* child btree block */
      union xfs_btree_key     *ckp;       /* child key pointer */
      union xfs_btree_ptr     *cpp;       /* child ptr pointer */
      union xfs_btree_key     *kp;        /* pointer to btree key */
      union xfs_btree_ptr     *pp;        /* pointer to block addr */
      union xfs_btree_ptr     nptr;       /* new block addr */
      int               level;            /* btree level */
      int               error;            /* error return code */
#ifdef DEBUG
      int               i;          /* loop counter */
#endif

      XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
      XFS_BTREE_STATS_INC(cur, newroot);

      ASSERT(cur->bc_flags & XFS_BTREE_ROOT_IN_INODE);

      level = cur->bc_nlevels - 1;

      block = xfs_btree_get_iroot(cur);
      pp = xfs_btree_ptr_addr(cur, 1, block);

      /* Allocate the new block. If we can't do it, we're toast. Give up. */
      error = cur->bc_ops->alloc_block(cur, pp, &nptr, 1, stat);
      if (error)
            goto error0;
      if (*stat == 0) {
            XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
            return 0;
      }
      XFS_BTREE_STATS_INC(cur, alloc);

      /* Copy the root into a real block. */
      error = xfs_btree_get_buf_block(cur, &nptr, 0, &cblock, &cbp);
      if (error)
            goto error0;

      memcpy(cblock, block, xfs_btree_block_len(cur));

      be16_add_cpu(&block->bb_level, 1);
      xfs_btree_set_numrecs(block, 1);
      cur->bc_nlevels++;
      cur->bc_ptrs[level + 1] = 1;

      kp = xfs_btree_key_addr(cur, 1, block);
      ckp = xfs_btree_key_addr(cur, 1, cblock);
      xfs_btree_copy_keys(cur, ckp, kp, xfs_btree_get_numrecs(cblock));

      cpp = xfs_btree_ptr_addr(cur, 1, cblock);
#ifdef DEBUG
      for (i = 0; i < be16_to_cpu(cblock->bb_numrecs); i++) {
            error = xfs_btree_check_ptr(cur, pp, i, level);
            if (error)
                  goto error0;
      }
#endif
      xfs_btree_copy_ptrs(cur, cpp, pp, xfs_btree_get_numrecs(cblock));

#ifdef DEBUG
      error = xfs_btree_check_ptr(cur, &nptr, 0, level);
      if (error)
            goto error0;
#endif
      xfs_btree_copy_ptrs(cur, pp, &nptr, 1);

      xfs_iroot_realloc(cur->bc_private.b.ip,
                    1 - xfs_btree_get_numrecs(cblock),
                    cur->bc_private.b.whichfork);

      xfs_btree_setbuf(cur, level, cbp);

      /*
       * Do all this logging at the end so that
       * the root is at the right level.
       */
      xfs_btree_log_block(cur, cbp, XFS_BB_ALL_BITS);
      xfs_btree_log_keys(cur, cbp, 1, be16_to_cpu(cblock->bb_numrecs));
      xfs_btree_log_ptrs(cur, cbp, 1, be16_to_cpu(cblock->bb_numrecs));

      *logflags |=
            XFS_ILOG_CORE | xfs_ilog_fbroot(cur->bc_private.b.whichfork);
      *stat = 1;
      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
      return 0;
error0:
      XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
      return error;
}

/*
 * Allocate a new root block, fill it in.
 */
STATIC int                    /* error */
xfs_btree_new_root(
      struct xfs_btree_cur    *cur, /* btree cursor */
      int               *stat)      /* success/failure */
{
      struct xfs_btree_block  *block;     /* one half of the old root block */
      struct xfs_buf          *bp;  /* buffer containing block */
      int               error;      /* error return value */
      struct xfs_buf          *lbp; /* left buffer pointer */
      struct xfs_btree_block  *left;      /* left btree block */
      struct xfs_buf          *nbp; /* new (root) buffer */
      struct xfs_btree_block  *new; /* new (root) btree block */
      int               nptr; /* new value for key index, 1 or 2 */
      struct xfs_buf          *rbp; /* right buffer pointer */
      struct xfs_btree_block  *right;     /* right btree block */
      union xfs_btree_ptr     rptr;
      union xfs_btree_ptr     lptr;

      XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
      XFS_BTREE_STATS_INC(cur, newroot);

      /* initialise our start point from the cursor */
      cur->bc_ops->init_ptr_from_cur(cur, &rptr);

      /* Allocate the new block. If we can't do it, we're toast. Give up. */
      error = cur->bc_ops->alloc_block(cur, &rptr, &lptr, 1, stat);
      if (error)
            goto error0;
      if (*stat == 0)
            goto out0;
      XFS_BTREE_STATS_INC(cur, alloc);

      /* Set up the new block. */
      error = xfs_btree_get_buf_block(cur, &lptr, 0, &new, &nbp);
      if (error)
            goto error0;

      /* Set the root in the holding structure  increasing the level by 1. */
      cur->bc_ops->set_root(cur, &lptr, 1);

      /*
       * At the previous root level there are now two blocks: the old root,
       * and the new block generated when it was split.  We don't know which
       * one the cursor is pointing at, so we set up variables "left" and
       * "right" for each case.
       */
      block = xfs_btree_get_block(cur, cur->bc_nlevels - 1, &bp);

#ifdef DEBUG
      error = xfs_btree_check_block(cur, block, cur->bc_nlevels - 1, bp);
      if (error)
            goto error0;
#endif

      xfs_btree_get_sibling(cur, block, &rptr, XFS_BB_RIGHTSIB);
      if (!xfs_btree_ptr_is_null(cur, &rptr)) {
            /* Our block is left, pick up the right block. */
            lbp = bp;
            xfs_btree_buf_to_ptr(cur, lbp, &lptr);
            left = block;
            error = xfs_btree_read_buf_block(cur, &rptr,
                              cur->bc_nlevels - 1, 0, &right, &rbp);
            if (error)
                  goto error0;
            bp = rbp;
            nptr = 1;
      } else {
            /* Our block is right, pick up the left block. */
            rbp = bp;
            xfs_btree_buf_to_ptr(cur, rbp, &rptr);
            right = block;
            xfs_btree_get_sibling(cur, right, &lptr, XFS_BB_LEFTSIB);
            error = xfs_btree_read_buf_block(cur, &lptr,
                              cur->bc_nlevels - 1, 0, &left, &lbp);
            if (error)
                  goto error0;
            bp = lbp;
            nptr = 2;
      }
      /* Fill in the new block's btree header and log it. */
      xfs_btree_init_block(cur, cur->bc_nlevels, 2, new);
      xfs_btree_log_block(cur, nbp, XFS_BB_ALL_BITS);
      ASSERT(!xfs_btree_ptr_is_null(cur, &lptr) &&
                  !xfs_btree_ptr_is_null(cur, &rptr));

      /* Fill in the key data in the new root. */
      if (xfs_btree_get_level(left) > 0) {
            xfs_btree_copy_keys(cur,
                        xfs_btree_key_addr(cur, 1, new),
                        xfs_btree_key_addr(cur, 1, left), 1);
            xfs_btree_copy_keys(cur,
                        xfs_btree_key_addr(cur, 2, new),
                        xfs_btree_key_addr(cur, 1, right), 1);
      } else {
            cur->bc_ops->init_key_from_rec(
                        xfs_btree_key_addr(cur, 1, new),
                        xfs_btree_rec_addr(cur, 1, left));
            cur->bc_ops->init_key_from_rec(
                        xfs_btree_key_addr(cur, 2, new),
                        xfs_btree_rec_addr(cur, 1, right));
      }
      xfs_btree_log_keys(cur, nbp, 1, 2);

      /* Fill in the pointer data in the new root. */
      xfs_btree_copy_ptrs(cur,
            xfs_btree_ptr_addr(cur, 1, new), &lptr, 1);
      xfs_btree_copy_ptrs(cur,
            xfs_btree_ptr_addr(cur, 2, new), &rptr, 1);
      xfs_btree_log_ptrs(cur, nbp, 1, 2);

      /* Fix up the cursor. */
      xfs_btree_setbuf(cur, cur->bc_nlevels, nbp);
      cur->bc_ptrs[cur->bc_nlevels] = nptr;
      cur->bc_nlevels++;
      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
      *stat = 1;
      return 0;
error0:
      XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
      return error;
out0:
      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
      *stat = 0;
      return 0;
}

STATIC int
xfs_btree_make_block_unfull(
      struct xfs_btree_cur    *cur, /* btree cursor */
      int               level,      /* btree level */
      int               numrecs,/* # of recs in block */
      int               *oindex,/* old tree index */
      int               *index,     /* new tree index */
      union xfs_btree_ptr     *nptr,      /* new btree ptr */
      struct xfs_btree_cur    **ncur,     /* new btree cursor */
      union xfs_btree_rec     *nrec,      /* new record */
      int               *stat)
{
      union xfs_btree_key     key;  /* new btree key value */
      int               error = 0;

      if ((cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) &&
          level == cur->bc_nlevels - 1) {
            struct xfs_inode *ip = cur->bc_private.b.ip;

            if (numrecs < cur->bc_ops->get_dmaxrecs(cur, level)) {
                  /* A root block that can be made bigger. */

                  xfs_iroot_realloc(ip, 1, cur->bc_private.b.whichfork);
            } else {
                  /* A root block that needs replacing */
                  int   logflags = 0;

                  error = xfs_btree_new_iroot(cur, &logflags, stat);
                  if (error || *stat == 0)
                        return error;

                  xfs_trans_log_inode(cur->bc_tp, ip, logflags);
            }

            return 0;
      }

      /* First, try shifting an entry to the right neighbor. */
      error = xfs_btree_rshift(cur, level, stat);
      if (error || *stat)
            return error;

      /* Next, try shifting an entry to the left neighbor. */
      error = xfs_btree_lshift(cur, level, stat);
      if (error)
            return error;

      if (*stat) {
            *oindex = *index = cur->bc_ptrs[level];
            return 0;
      }

      /*
       * Next, try splitting the current block in half.
       *
       * If this works we have to re-set our variables because we
       * could be in a different block now.
       */
      error = xfs_btree_split(cur, level, nptr, &key, ncur, stat);
      if (error || *stat == 0)
            return error;


      *index = cur->bc_ptrs[level];
      cur->bc_ops->init_rec_from_key(&key, nrec);
      return 0;
}

/*
 * Insert one record/level.  Return information to the caller
 * allowing the next level up to proceed if necessary.
 */
STATIC int
xfs_btree_insrec(
      struct xfs_btree_cur    *cur, /* btree cursor */
      int               level,      /* level to insert record at */
      union xfs_btree_ptr     *ptrp,      /* i/o: block number inserted */
      union xfs_btree_rec     *recp,      /* i/o: record data inserted */
      struct xfs_btree_cur    **curp,     /* output: new cursor replacing cur */
      int               *stat)      /* success/failure */
{
      struct xfs_btree_block  *block;     /* btree block */
      struct xfs_buf          *bp;  /* buffer for block */
      union xfs_btree_key     key;  /* btree key */
      union xfs_btree_ptr     nptr; /* new block ptr */
      struct xfs_btree_cur    *ncur;      /* new btree cursor */
      union xfs_btree_rec     nrec; /* new record count */
      int               optr; /* old key/record index */
      int               ptr;  /* key/record index */
      int               numrecs;/* number of records */
      int               error;      /* error return value */
#ifdef DEBUG
      int               i;
#endif

      XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
      XFS_BTREE_TRACE_ARGIPR(cur, level, *ptrp, recp);

      ncur = NULL;

      /*
       * If we have an external root pointer, and we've made it to the
       * root level, allocate a new root block and we're done.
       */
      if (!(cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) &&
          (level >= cur->bc_nlevels)) {
            error = xfs_btree_new_root(cur, stat);
            xfs_btree_set_ptr_null(cur, ptrp);

            XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
            return error;
      }

      /* If we're off the left edge, return failure. */
      ptr = cur->bc_ptrs[level];
      if (ptr == 0) {
            XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
            *stat = 0;
            return 0;
      }

      /* Make a key out of the record data to be inserted, and save it. */
      cur->bc_ops->init_key_from_rec(&key, recp);

      optr = ptr;

      XFS_BTREE_STATS_INC(cur, insrec);

      /* Get pointers to the btree buffer and block. */
      block = xfs_btree_get_block(cur, level, &bp);
      numrecs = xfs_btree_get_numrecs(block);

#ifdef DEBUG
      error = xfs_btree_check_block(cur, block, level, bp);
      if (error)
            goto error0;

      /* Check that the new entry is being inserted in the right place. */
      if (ptr <= numrecs) {
            if (level == 0) {
                  ASSERT(cur->bc_ops->recs_inorder(cur, recp,
                        xfs_btree_rec_addr(cur, ptr, block)));
            } else {
                  ASSERT(cur->bc_ops->keys_inorder(cur, &key,
                        xfs_btree_key_addr(cur, ptr, block)));
            }
      }
#endif

      /*
       * If the block is full, we can't insert the new entry until we
       * make the block un-full.
       */
      xfs_btree_set_ptr_null(cur, &nptr);
      if (numrecs == cur->bc_ops->get_maxrecs(cur, level)) {
            error = xfs_btree_make_block_unfull(cur, level, numrecs,
                              &optr, &ptr, &nptr, &ncur, &nrec, stat);
            if (error || *stat == 0)
                  goto error0;
      }

      /*
       * The current block may have changed if the block was
       * previously full and we have just made space in it.
       */
      block = xfs_btree_get_block(cur, level, &bp);
      numrecs = xfs_btree_get_numrecs(block);

#ifdef DEBUG
      error = xfs_btree_check_block(cur, block, level, bp);
      if (error)
            return error;
#endif

      /*
       * At this point we know there's room for our new entry in the block
       * we're pointing at.
       */
      XFS_BTREE_STATS_ADD(cur, moves, numrecs - ptr + 1);

      if (level > 0) {
            /* It's a nonleaf. make a hole in the keys and ptrs */
            union xfs_btree_key     *kp;
            union xfs_btree_ptr     *pp;

            kp = xfs_btree_key_addr(cur, ptr, block);
            pp = xfs_btree_ptr_addr(cur, ptr, block);

#ifdef DEBUG
            for (i = numrecs - ptr; i >= 0; i--) {
                  error = xfs_btree_check_ptr(cur, pp, i, level);
                  if (error)
                        return error;
            }
#endif

            xfs_btree_shift_keys(cur, kp, 1, numrecs - ptr + 1);
            xfs_btree_shift_ptrs(cur, pp, 1, numrecs - ptr + 1);

#ifdef DEBUG
            error = xfs_btree_check_ptr(cur, ptrp, 0, level);
            if (error)
                  goto error0;
#endif

            /* Now put the new data in, bump numrecs and log it. */
            xfs_btree_copy_keys(cur, kp, &key, 1);
            xfs_btree_copy_ptrs(cur, pp, ptrp, 1);
            numrecs++;
            xfs_btree_set_numrecs(block, numrecs);
            xfs_btree_log_ptrs(cur, bp, ptr, numrecs);
            xfs_btree_log_keys(cur, bp, ptr, numrecs);
#ifdef DEBUG
            if (ptr < numrecs) {
                  ASSERT(cur->bc_ops->keys_inorder(cur, kp,
                        xfs_btree_key_addr(cur, ptr + 1, block)));
            }
#endif
      } else {
            /* It's a leaf. make a hole in the records */
            union xfs_btree_rec             *rp;

            rp = xfs_btree_rec_addr(cur, ptr, block);

            xfs_btree_shift_recs(cur, rp, 1, numrecs - ptr + 1);

            /* Now put the new data in, bump numrecs and log it. */
            xfs_btree_copy_recs(cur, rp, recp, 1);
            xfs_btree_set_numrecs(block, ++numrecs);
            xfs_btree_log_recs(cur, bp, ptr, numrecs);
#ifdef DEBUG
            if (ptr < numrecs) {
                  ASSERT(cur->bc_ops->recs_inorder(cur, rp,
                        xfs_btree_rec_addr(cur, ptr + 1, block)));
            }
#endif
      }

      /* Log the new number of records in the btree header. */
      xfs_btree_log_block(cur, bp, XFS_BB_NUMRECS);

      /* If we inserted at the start of a block, update the parents' keys. */
      if (optr == 1) {
            error = xfs_btree_updkey(cur, &key, level + 1);
            if (error)
                  goto error0;
      }

      /*
       * If we are tracking the last record in the tree and
       * we are at the far right edge of the tree, update it.
       */
      if (xfs_btree_is_lastrec(cur, block, level)) {
            cur->bc_ops->update_lastrec(cur, block, recp,
                                  ptr, LASTREC_INSREC);
      }

      /*
       * Return the new block number, if any.
       * If there is one, give back a record value and a cursor too.
       */
      *ptrp = nptr;
      if (!xfs_btree_ptr_is_null(cur, &nptr)) {
            *recp = nrec;
            *curp = ncur;
      }

      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
      *stat = 1;
      return 0;

error0:
      XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
      return error;
}

/*
 * Insert the record at the point referenced by cur.
 *
 * A multi-level split of the tree on insert will invalidate the original
 * cursor.  All callers of this function should assume that the cursor is
 * no longer valid and revalidate it.
 */
int
xfs_btree_insert(
      struct xfs_btree_cur    *cur,
      int               *stat)
{
      int               error;      /* error return value */
      int               i;    /* result value, 0 for failure */
      int               level;      /* current level number in btree */
      union xfs_btree_ptr     nptr; /* new block number (split result) */
      struct xfs_btree_cur    *ncur;      /* new cursor (split result) */
      struct xfs_btree_cur    *pcur;      /* previous level's cursor */
      union xfs_btree_rec     rec;  /* record to insert */

      level = 0;
      ncur = NULL;
      pcur = cur;

      xfs_btree_set_ptr_null(cur, &nptr);
      cur->bc_ops->init_rec_from_cur(cur, &rec);

      /*
       * Loop going up the tree, starting at the leaf level.
       * Stop when we don't get a split block, that must mean that
       * the insert is finished with this level.
       */
      do {
            /*
             * Insert nrec/nptr into this level of the tree.
             * Note if we fail, nptr will be null.
             */
            error = xfs_btree_insrec(pcur, level, &nptr, &rec, &ncur, &i);
            if (error) {
                  if (pcur != cur)
                        xfs_btree_del_cursor(pcur, XFS_BTREE_ERROR);
                  goto error0;
            }

            XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
            level++;

            /*
             * See if the cursor we just used is trash.
             * Can't trash the caller's cursor, but otherwise we should
             * if ncur is a new cursor or we're about to be done.
             */
            if (pcur != cur &&
                (ncur || xfs_btree_ptr_is_null(cur, &nptr))) {
                  /* Save the state from the cursor before we trash it */
                  if (cur->bc_ops->update_cursor)
                        cur->bc_ops->update_cursor(pcur, cur);
                  cur->bc_nlevels = pcur->bc_nlevels;
                  xfs_btree_del_cursor(pcur, XFS_BTREE_NOERROR);
            }
            /* If we got a new cursor, switch to it. */
            if (ncur) {
                  pcur = ncur;
                  ncur = NULL;
            }
      } while (!xfs_btree_ptr_is_null(cur, &nptr));

      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
      *stat = i;
      return 0;
error0:
      XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
      return error;
}

/*
 * Try to merge a non-leaf block back into the inode root.
 *
 * Note: the killroot names comes from the fact that we're effectively
 * killing the old root block.  But because we can't just delete the
 * inode we have to copy the single block it was pointing to into the
 * inode.
 */
int
xfs_btree_kill_iroot(
      struct xfs_btree_cur    *cur)
{
      int               whichfork = cur->bc_private.b.whichfork;
      struct xfs_inode  *ip = cur->bc_private.b.ip;
      struct xfs_ifork  *ifp = XFS_IFORK_PTR(ip, whichfork);
      struct xfs_btree_block  *block;
      struct xfs_btree_block  *cblock;
      union xfs_btree_key     *kp;
      union xfs_btree_key     *ckp;
      union xfs_btree_ptr     *pp;
      union xfs_btree_ptr     *cpp;
      struct xfs_buf          *cbp;
      int               level;
      int               index;
      int               numrecs;
#ifdef DEBUG
      union xfs_btree_ptr     ptr;
      int               i;
#endif

      XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);

      ASSERT(cur->bc_flags & XFS_BTREE_ROOT_IN_INODE);
      ASSERT(cur->bc_nlevels > 1);

      /*
       * Don't deal with the root block needs to be a leaf case.
       * We're just going to turn the thing back into extents anyway.
       */
      level = cur->bc_nlevels - 1;
      if (level == 1)
            goto out0;

      /*
       * Give up if the root has multiple children.
       */
      block = xfs_btree_get_iroot(cur);
      if (xfs_btree_get_numrecs(block) != 1)
            goto out0;

      cblock = xfs_btree_get_block(cur, level - 1, &cbp);
      numrecs = xfs_btree_get_numrecs(cblock);

      /*
       * Only do this if the next level will fit.
       * Then the data must be copied up to the inode,
       * instead of freeing the root you free the next level.
       */
      if (numrecs > cur->bc_ops->get_dmaxrecs(cur, level))
            goto out0;

      XFS_BTREE_STATS_INC(cur, killroot);

#ifdef DEBUG
      xfs_btree_get_sibling(cur, block, &ptr, XFS_BB_LEFTSIB);
      ASSERT(xfs_btree_ptr_is_null(cur, &ptr));
      xfs_btree_get_sibling(cur, block, &ptr, XFS_BB_RIGHTSIB);
      ASSERT(xfs_btree_ptr_is_null(cur, &ptr));
#endif

      index = numrecs - cur->bc_ops->get_maxrecs(cur, level);
      if (index) {
            xfs_iroot_realloc(cur->bc_private.b.ip, index,
                          cur->bc_private.b.whichfork);
            block = ifp->if_broot;
      }

      be16_add_cpu(&block->bb_numrecs, index);
      ASSERT(block->bb_numrecs == cblock->bb_numrecs);

      kp = xfs_btree_key_addr(cur, 1, block);
      ckp = xfs_btree_key_addr(cur, 1, cblock);
      xfs_btree_copy_keys(cur, kp, ckp, numrecs);

      pp = xfs_btree_ptr_addr(cur, 1, block);
      cpp = xfs_btree_ptr_addr(cur, 1, cblock);
#ifdef DEBUG
      for (i = 0; i < numrecs; i++) {
            int         error;

            error = xfs_btree_check_ptr(cur, cpp, i, level - 1);
            if (error) {
                  XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
                  return error;
            }
      }
#endif
      xfs_btree_copy_ptrs(cur, pp, cpp, numrecs);

      cur->bc_ops->free_block(cur, cbp);
      XFS_BTREE_STATS_INC(cur, free);

      cur->bc_bufs[level - 1] = NULL;
      be16_add_cpu(&block->bb_level, -1);
      xfs_trans_log_inode(cur->bc_tp, ip,
            XFS_ILOG_CORE | xfs_ilog_fbroot(cur->bc_private.b.whichfork));
      cur->bc_nlevels--;
out0:
      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
      return 0;
}

STATIC int
xfs_btree_dec_cursor(
      struct xfs_btree_cur    *cur,
      int               level,
      int               *stat)
{
      int               error;
      int               i;

      if (level > 0) {
            error = xfs_btree_decrement(cur, level, &i);
            if (error)
                  return error;
      }

      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
      *stat = 1;
      return 0;
}

/*
 * Single level of the btree record deletion routine.
 * Delete record pointed to by cur/level.
 * Remove the record from its block then rebalance the tree.
 * Return 0 for error, 1 for done, 2 to go on to the next level.
 */
STATIC int                          /* error */
xfs_btree_delrec(
      struct xfs_btree_cur    *cur,       /* btree cursor */
      int               level,            /* level removing record from */
      int               *stat)            /* fail/done/go-on */
{
      struct xfs_btree_block  *block;           /* btree block */
      union xfs_btree_ptr     cptr;       /* current block ptr */
      struct xfs_buf          *bp;        /* buffer for block */
      int               error;            /* error return value */
      int               i;          /* loop counter */
      union xfs_btree_key     key;        /* storage for keyp */
      union xfs_btree_key     *keyp = &key;     /* passed to the next level */
      union xfs_btree_ptr     lptr;       /* left sibling block ptr */
      struct xfs_buf          *lbp;       /* left buffer pointer */
      struct xfs_btree_block  *left;            /* left btree block */
      int               lrecs = 0;  /* left record count */
      int               ptr;        /* key/record index */
      union xfs_btree_ptr     rptr;       /* right sibling block ptr */
      struct xfs_buf          *rbp;       /* right buffer pointer */
      struct xfs_btree_block  *right;           /* right btree block */
      struct xfs_btree_block  *rrblock;   /* right-right btree block */
      struct xfs_buf          *rrbp;            /* right-right buffer pointer */
      int               rrecs = 0;  /* right record count */
      struct xfs_btree_cur    *tcur;            /* temporary btree cursor */
      int               numrecs;    /* temporary numrec count */

      XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
      XFS_BTREE_TRACE_ARGI(cur, level);

      tcur = NULL;

      /* Get the index of the entry being deleted, check for nothing there. */
      ptr = cur->bc_ptrs[level];
      if (ptr == 0) {
            XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
            *stat = 0;
            return 0;
      }

      /* Get the buffer & block containing the record or key/ptr. */
      block = xfs_btree_get_block(cur, level, &bp);
      numrecs = xfs_btree_get_numrecs(block);

#ifdef DEBUG
      error = xfs_btree_check_block(cur, block, level, bp);
      if (error)
            goto error0;
#endif

      /* Fail if we're off the end of the block. */
      if (ptr > numrecs) {
            XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
            *stat = 0;
            return 0;
      }

      XFS_BTREE_STATS_INC(cur, delrec);
      XFS_BTREE_STATS_ADD(cur, moves, numrecs - ptr);

      /* Excise the entries being deleted. */
      if (level > 0) {
            /* It's a nonleaf. operate on keys and ptrs */
            union xfs_btree_key     *lkp;
            union xfs_btree_ptr     *lpp;

            lkp = xfs_btree_key_addr(cur, ptr + 1, block);
            lpp = xfs_btree_ptr_addr(cur, ptr + 1, block);

#ifdef DEBUG
            for (i = 0; i < numrecs - ptr; i++) {
                  error = xfs_btree_check_ptr(cur, lpp, i, level);
                  if (error)
                        goto error0;
            }
#endif

            if (ptr < numrecs) {
                  xfs_btree_shift_keys(cur, lkp, -1, numrecs - ptr);
                  xfs_btree_shift_ptrs(cur, lpp, -1, numrecs - ptr);
                  xfs_btree_log_keys(cur, bp, ptr, numrecs - 1);
                  xfs_btree_log_ptrs(cur, bp, ptr, numrecs - 1);
            }

            /*
             * If it's the first record in the block, we'll need to pass a
             * key up to the next level (updkey).
             */
            if (ptr == 1)
                  keyp = xfs_btree_key_addr(cur, 1, block);
      } else {
            /* It's a leaf. operate on records */
            if (ptr < numrecs) {
                  xfs_btree_shift_recs(cur,
                        xfs_btree_rec_addr(cur, ptr + 1, block),
                        -1, numrecs - ptr);
                  xfs_btree_log_recs(cur, bp, ptr, numrecs - 1);
            }

            /*
             * If it's the first record in the block, we'll need a key
             * structure to pass up to the next level (updkey).
             */
            if (ptr == 1) {
                  cur->bc_ops->init_key_from_rec(&key,
                              xfs_btree_rec_addr(cur, 1, block));
                  keyp = &key;
            }
      }

      /*
       * Decrement and log the number of entries in the block.
       */
      xfs_btree_set_numrecs(block, --numrecs);
      xfs_btree_log_block(cur, bp, XFS_BB_NUMRECS);

      /*
       * If we are tracking the last record in the tree and
       * we are at the far right edge of the tree, update it.
       */
      if (xfs_btree_is_lastrec(cur, block, level)) {
            cur->bc_ops->update_lastrec(cur, block, NULL,
                                  ptr, LASTREC_DELREC);
      }

      /*
       * We're at the root level.  First, shrink the root block in-memory.
       * Try to get rid of the next level down.  If we can't then there's
       * nothing left to do.
       */
      if (level == cur->bc_nlevels - 1) {
            if (cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) {
                  xfs_iroot_realloc(cur->bc_private.b.ip, -1,
                                cur->bc_private.b.whichfork);

                  error = xfs_btree_kill_iroot(cur);
                  if (error)
                        goto error0;

                  error = xfs_btree_dec_cursor(cur, level, stat);
                  if (error)
                        goto error0;
                  *stat = 1;
                  return 0;
            }

            /*
             * If this is the root level, and there's only one entry left,
             * and it's NOT the leaf level, then we can get rid of this
             * level.
             */
            if (numrecs == 1 && level > 0) {
                  union xfs_btree_ptr     *pp;
                  /*
                   * pp is still set to the first pointer in the block.
                   * Make it the new root of the btree.
                   */
                  pp = xfs_btree_ptr_addr(cur, 1, block);
                  error = cur->bc_ops->kill_root(cur, bp, level, pp);
                  if (error)
                        goto error0;
            } else if (level > 0) {
                  error = xfs_btree_dec_cursor(cur, level, stat);
                  if (error)
                        goto error0;
            }
            *stat = 1;
            return 0;
      }

      /*
       * If we deleted the leftmost entry in the block, update the
       * key values above us in the tree.
       */
      if (ptr == 1) {
            error = xfs_btree_updkey(cur, keyp, level + 1);
            if (error)
                  goto error0;
      }

      /*
       * If the number of records remaining in the block is at least
       * the minimum, we're done.
       */
      if (numrecs >= cur->bc_ops->get_minrecs(cur, level)) {
            error = xfs_btree_dec_cursor(cur, level, stat);
            if (error)
                  goto error0;
            return 0;
      }

      /*
       * Otherwise, we have to move some records around to keep the
       * tree balanced.  Look at the left and right sibling blocks to
       * see if we can re-balance by moving only one record.
       */
      xfs_btree_get_sibling(cur, block, &rptr, XFS_BB_RIGHTSIB);
      xfs_btree_get_sibling(cur, block, &lptr, XFS_BB_LEFTSIB);

      if (cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) {
            /*
             * One child of root, need to get a chance to copy its contents
             * into the root and delete it. Can't go up to next level,
             * there's nothing to delete there.
             */
            if (xfs_btree_ptr_is_null(cur, &rptr) &&
                xfs_btree_ptr_is_null(cur, &lptr) &&
                level == cur->bc_nlevels - 2) {
                  error = xfs_btree_kill_iroot(cur);
                  if (!error)
                        error = xfs_btree_dec_cursor(cur, level, stat);
                  if (error)
                        goto error0;
                  return 0;
            }
      }

      ASSERT(!xfs_btree_ptr_is_null(cur, &rptr) ||
             !xfs_btree_ptr_is_null(cur, &lptr));

      /*
       * Duplicate the cursor so our btree manipulations here won't
       * disrupt the next level up.
       */
      error = xfs_btree_dup_cursor(cur, &tcur);
      if (error)
            goto error0;

      /*
       * If there's a right sibling, see if it's ok to shift an entry
       * out of it.
       */
      if (!xfs_btree_ptr_is_null(cur, &rptr)) {
            /*
             * Move the temp cursor to the last entry in the next block.
             * Actually any entry but the first would suffice.
             */
            i = xfs_btree_lastrec(tcur, level);
            XFS_WANT_CORRUPTED_GOTO(i == 1, error0);

            error = xfs_btree_increment(tcur, level, &i);
            if (error)
                  goto error0;
            XFS_WANT_CORRUPTED_GOTO(i == 1, error0);

            i = xfs_btree_lastrec(tcur, level);
            XFS_WANT_CORRUPTED_GOTO(i == 1, error0);

            /* Grab a pointer to the block. */
            right = xfs_btree_get_block(tcur, level, &rbp);
#ifdef DEBUG
            error = xfs_btree_check_block(tcur, right, level, rbp);
            if (error)
                  goto error0;
#endif
            /* Grab the current block number, for future use. */
            xfs_btree_get_sibling(tcur, right, &cptr, XFS_BB_LEFTSIB);

            /*
             * If right block is full enough so that removing one entry
             * won't make it too empty, and left-shifting an entry out
             * of right to us works, we're done.
             */
            if (xfs_btree_get_numrecs(right) - 1 >=
                cur->bc_ops->get_minrecs(tcur, level)) {
                  error = xfs_btree_lshift(tcur, level, &i);
                  if (error)
                        goto error0;
                  if (i) {
                        ASSERT(xfs_btree_get_numrecs(block) >=
                               cur->bc_ops->get_minrecs(tcur, level));

                        xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);
                        tcur = NULL;

                        error = xfs_btree_dec_cursor(cur, level, stat);
                        if (error)
                              goto error0;
                        return 0;
                  }
            }

            /*
             * Otherwise, grab the number of records in right for
             * future reference, and fix up the temp cursor to point
             * to our block again (last record).
             */
            rrecs = xfs_btree_get_numrecs(right);
            if (!xfs_btree_ptr_is_null(cur, &lptr)) {
                  i = xfs_btree_firstrec(tcur, level);
                  XFS_WANT_CORRUPTED_GOTO(i == 1, error0);

                  error = xfs_btree_decrement(tcur, level, &i);
                  if (error)
                        goto error0;
                  XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
            }
      }

      /*
       * If there's a left sibling, see if it's ok to shift an entry
       * out of it.
       */
      if (!xfs_btree_ptr_is_null(cur, &lptr)) {
            /*
             * Move the temp cursor to the first entry in the
             * previous block.
             */
            i = xfs_btree_firstrec(tcur, level);
            XFS_WANT_CORRUPTED_GOTO(i == 1, error0);

            error = xfs_btree_decrement(tcur, level, &i);
            if (error)
                  goto error0;
            i = xfs_btree_firstrec(tcur, level);
            XFS_WANT_CORRUPTED_GOTO(i == 1, error0);

            /* Grab a pointer to the block. */
            left = xfs_btree_get_block(tcur, level, &lbp);
#ifdef DEBUG
            error = xfs_btree_check_block(cur, left, level, lbp);
            if (error)
                  goto error0;
#endif
            /* Grab the current block number, for future use. */
            xfs_btree_get_sibling(tcur, left, &cptr, XFS_BB_RIGHTSIB);

            /*
             * If left block is full enough so that removing one entry
             * won't make it too empty, and right-shifting an entry out
             * of left to us works, we're done.
             */
            if (xfs_btree_get_numrecs(left) - 1 >=
                cur->bc_ops->get_minrecs(tcur, level)) {
                  error = xfs_btree_rshift(tcur, level, &i);
                  if (error)
                        goto error0;
                  if (i) {
                        ASSERT(xfs_btree_get_numrecs(block) >=
                               cur->bc_ops->get_minrecs(tcur, level));
                        xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);
                        tcur = NULL;
                        if (level == 0)
                              cur->bc_ptrs[0]++;
                        XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
                        *stat = 1;
                        return 0;
                  }
            }

            /*
             * Otherwise, grab the number of records in right for
             * future reference.
             */
            lrecs = xfs_btree_get_numrecs(left);
      }

      /* Delete the temp cursor, we're done with it. */
      xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);
      tcur = NULL;

      /* If here, we need to do a join to keep the tree balanced. */
      ASSERT(!xfs_btree_ptr_is_null(cur, &cptr));

      if (!xfs_btree_ptr_is_null(cur, &lptr) &&
          lrecs + xfs_btree_get_numrecs(block) <=
                  cur->bc_ops->get_maxrecs(cur, level)) {
            /*
             * Set "right" to be the starting block,
             * "left" to be the left neighbor.
             */
            rptr = cptr;
            right = block;
            rbp = bp;
            error = xfs_btree_read_buf_block(cur, &lptr, level,
                                          0, &left, &lbp);
            if (error)
                  goto error0;

      /*
       * If that won't work, see if we can join with the right neighbor block.
       */
      } else if (!xfs_btree_ptr_is_null(cur, &rptr) &&
               rrecs + xfs_btree_get_numrecs(block) <=
                  cur->bc_ops->get_maxrecs(cur, level)) {
            /*
             * Set "left" to be the starting block,
             * "right" to be the right neighbor.
             */
            lptr = cptr;
            left = block;
            lbp = bp;
            error = xfs_btree_read_buf_block(cur, &rptr, level,
                                          0, &right, &rbp);
            if (error)
                  goto error0;

      /*
       * Otherwise, we can't fix the imbalance.
       * Just return.  This is probably a logic error, but it's not fatal.
       */
      } else {
            error = xfs_btree_dec_cursor(cur, level, stat);
            if (error)
                  goto error0;
            return 0;
      }

      rrecs = xfs_btree_get_numrecs(right);
      lrecs = xfs_btree_get_numrecs(left);

      /*
       * We're now going to join "left" and "right" by moving all the stuff
       * in "right" to "left" and deleting "right".
       */
      XFS_BTREE_STATS_ADD(cur, moves, rrecs);
      if (level > 0) {
            /* It's a non-leaf.  Move keys and pointers. */
            union xfs_btree_key     *lkp; /* left btree key */
            union xfs_btree_ptr     *lpp; /* left address pointer */
            union xfs_btree_key     *rkp; /* right btree key */
            union xfs_btree_ptr     *rpp; /* right address pointer */

            lkp = xfs_btree_key_addr(cur, lrecs + 1, left);
            lpp = xfs_btree_ptr_addr(cur, lrecs + 1, left);
            rkp = xfs_btree_key_addr(cur, 1, right);
            rpp = xfs_btree_ptr_addr(cur, 1, right);
#ifdef DEBUG
            for (i = 1; i < rrecs; i++) {
                  error = xfs_btree_check_ptr(cur, rpp, i, level);
                  if (error)
                        goto error0;
            }
#endif
            xfs_btree_copy_keys(cur, lkp, rkp, rrecs);
            xfs_btree_copy_ptrs(cur, lpp, rpp, rrecs);

            xfs_btree_log_keys(cur, lbp, lrecs + 1, lrecs + rrecs);
            xfs_btree_log_ptrs(cur, lbp, lrecs + 1, lrecs + rrecs);
      } else {
            /* It's a leaf.  Move records.  */
            union xfs_btree_rec     *lrp; /* left record pointer */
            union xfs_btree_rec     *rrp; /* right record pointer */

            lrp = xfs_btree_rec_addr(cur, lrecs + 1, left);
            rrp = xfs_btree_rec_addr(cur, 1, right);

            xfs_btree_copy_recs(cur, lrp, rrp, rrecs);
            xfs_btree_log_recs(cur, lbp, lrecs + 1, lrecs + rrecs);
      }

      XFS_BTREE_STATS_INC(cur, join);

      /*
       * Fix up the number of records and right block pointer in the
       * surviving block, and log it.
       */
      xfs_btree_set_numrecs(left, lrecs + rrecs);
      xfs_btree_get_sibling(cur, right, &cptr, XFS_BB_RIGHTSIB),
      xfs_btree_set_sibling(cur, left, &cptr, XFS_BB_RIGHTSIB);
      xfs_btree_log_block(cur, lbp, XFS_BB_NUMRECS | XFS_BB_RIGHTSIB);

      /* If there is a right sibling, point it to the remaining block. */
      xfs_btree_get_sibling(cur, left, &cptr, XFS_BB_RIGHTSIB);
      if (!xfs_btree_ptr_is_null(cur, &cptr)) {
            error = xfs_btree_read_buf_block(cur, &cptr, level,
                                          0, &rrblock, &rrbp);
            if (error)
                  goto error0;
            xfs_btree_set_sibling(cur, rrblock, &lptr, XFS_BB_LEFTSIB);
            xfs_btree_log_block(cur, rrbp, XFS_BB_LEFTSIB);
      }

      /* Free the deleted block. */
      error = cur->bc_ops->free_block(cur, rbp);
      if (error)
            goto error0;
      XFS_BTREE_STATS_INC(cur, free);

      /*
       * If we joined with the left neighbor, set the buffer in the
       * cursor to the left block, and fix up the index.
       */
      if (bp != lbp) {
            cur->bc_bufs[level] = lbp;
            cur->bc_ptrs[level] += lrecs;
            cur->bc_ra[level] = 0;
      }
      /*
       * If we joined with the right neighbor and there's a level above
       * us, increment the cursor at that level.
       */
      else if ((cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) ||
               (level + 1 < cur->bc_nlevels)) {
            error = xfs_btree_increment(cur, level + 1, &i);
            if (error)
                  goto error0;
      }

      /*
       * Readjust the ptr at this level if it's not a leaf, since it's
       * still pointing at the deletion point, which makes the cursor
       * inconsistent.  If this makes the ptr 0, the caller fixes it up.
       * We can't use decrement because it would change the next level up.
       */
      if (level > 0)
            cur->bc_ptrs[level]--;

      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
      /* Return value means the next level up has something to do. */
      *stat = 2;
      return 0;

error0:
      XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
      if (tcur)
            xfs_btree_del_cursor(tcur, XFS_BTREE_ERROR);
      return error;
}

/*
 * Delete the record pointed to by cur.
 * The cursor refers to the place where the record was (could be inserted)
 * when the operation returns.
 */
int                           /* error */
xfs_btree_delete(
      struct xfs_btree_cur    *cur,
      int               *stat)      /* success/failure */
{
      int               error;      /* error return value */
      int               level;
      int               i;

      XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);

      /*
       * Go up the tree, starting at leaf level.
       *
       * If 2 is returned then a join was done; go to the next level.
       * Otherwise we are done.
       */
      for (level = 0, i = 2; i == 2; level++) {
            error = xfs_btree_delrec(cur, level, &i);
            if (error)
                  goto error0;
      }

      if (i == 0) {
            for (level = 1; level < cur->bc_nlevels; level++) {
                  if (cur->bc_ptrs[level] == 0) {
                        error = xfs_btree_decrement(cur, level, &i);
                        if (error)
                              goto error0;
                        break;
                  }
            }
      }

      XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
      *stat = i;
      return 0;
error0:
      XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
      return error;
}

/*
 * Get the data from the pointed-to record.
 */
int                           /* error */
xfs_btree_get_rec(
      struct xfs_btree_cur    *cur, /* btree cursor */
      union xfs_btree_rec     **recp,     /* output: btree record */
      int               *stat)      /* output: success/failure */
{
      struct xfs_btree_block  *block;     /* btree block */
      struct xfs_buf          *bp;  /* buffer pointer */
      int               ptr;  /* record number */
#ifdef DEBUG
      int               error;      /* error return value */
#endif

      ptr = cur->bc_ptrs[0];
      block = xfs_btree_get_block(cur, 0, &bp);

#ifdef DEBUG
      error = xfs_btree_check_block(cur, block, 0, bp);
      if (error)
            return error;
#endif

      /*
       * Off the right end or left end, return failure.
       */
      if (ptr > xfs_btree_get_numrecs(block) || ptr <= 0) {
            *stat = 0;
            return 0;
      }

      /*
       * Point to the record and extract its data.
       */
      *recp = xfs_btree_rec_addr(cur, ptr, block);
      *stat = 1;
      return 0;
}

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