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super.c

/*
 *  linux/fs/ext4/super.c
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card (card@masi.ibp.fr)
 * Laboratoire MASI - Institut Blaise Pascal
 * Universite Pierre et Marie Curie (Paris VI)
 *
 *  from
 *
 *  linux/fs/minix/inode.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  Big-endian to little-endian byte-swapping/bitmaps by
 *        David S. Miller (davem@caip.rutgers.edu), 1995
 */

#include <linux/module.h>
#include <linux/string.h>
#include <linux/fs.h>
#include <linux/time.h>
#include <linux/vmalloc.h>
#include <linux/jbd2.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/parser.h>
#include <linux/smp_lock.h>
#include <linux/buffer_head.h>
#include <linux/exportfs.h>
#include <linux/vfs.h>
#include <linux/random.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/quotaops.h>
#include <linux/seq_file.h>
#include <linux/proc_fs.h>
#include <linux/ctype.h>
#include <linux/log2.h>
#include <linux/crc16.h>
#include <asm/uaccess.h>

#include "ext4.h"
#include "ext4_jbd2.h"
#include "xattr.h"
#include "acl.h"

#define CREATE_TRACE_POINTS
#include <trace/events/ext4.h>

static int default_mb_history_length = 1000;

module_param_named(default_mb_history_length, default_mb_history_length,
               int, 0644);
MODULE_PARM_DESC(default_mb_history_length,
             "Default number of entries saved for mb_history");

struct proc_dir_entry *ext4_proc_root;
static struct kset *ext4_kset;

static int ext4_load_journal(struct super_block *, struct ext4_super_block *,
                       unsigned long journal_devnum);
static int ext4_commit_super(struct super_block *sb, int sync);
static void ext4_mark_recovery_complete(struct super_block *sb,
                              struct ext4_super_block *es);
static void ext4_clear_journal_err(struct super_block *sb,
                           struct ext4_super_block *es);
static int ext4_sync_fs(struct super_block *sb, int wait);
static const char *ext4_decode_error(struct super_block *sb, int errno,
                             char nbuf[16]);
static int ext4_remount(struct super_block *sb, int *flags, char *data);
static int ext4_statfs(struct dentry *dentry, struct kstatfs *buf);
static int ext4_unfreeze(struct super_block *sb);
static void ext4_write_super(struct super_block *sb);
static int ext4_freeze(struct super_block *sb);


ext4_fsblk_t ext4_block_bitmap(struct super_block *sb,
                         struct ext4_group_desc *bg)
{
      return le32_to_cpu(bg->bg_block_bitmap_lo) |
            (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT ?
             (ext4_fsblk_t)le32_to_cpu(bg->bg_block_bitmap_hi) << 32 : 0);
}

ext4_fsblk_t ext4_inode_bitmap(struct super_block *sb,
                         struct ext4_group_desc *bg)
{
      return le32_to_cpu(bg->bg_inode_bitmap_lo) |
            (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT ?
             (ext4_fsblk_t)le32_to_cpu(bg->bg_inode_bitmap_hi) << 32 : 0);
}

ext4_fsblk_t ext4_inode_table(struct super_block *sb,
                        struct ext4_group_desc *bg)
{
      return le32_to_cpu(bg->bg_inode_table_lo) |
            (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT ?
             (ext4_fsblk_t)le32_to_cpu(bg->bg_inode_table_hi) << 32 : 0);
}

__u32 ext4_free_blks_count(struct super_block *sb,
                        struct ext4_group_desc *bg)
{
      return le16_to_cpu(bg->bg_free_blocks_count_lo) |
            (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT ?
             (__u32)le16_to_cpu(bg->bg_free_blocks_count_hi) << 16 : 0);
}

__u32 ext4_free_inodes_count(struct super_block *sb,
                        struct ext4_group_desc *bg)
{
      return le16_to_cpu(bg->bg_free_inodes_count_lo) |
            (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT ?
             (__u32)le16_to_cpu(bg->bg_free_inodes_count_hi) << 16 : 0);
}

__u32 ext4_used_dirs_count(struct super_block *sb,
                        struct ext4_group_desc *bg)
{
      return le16_to_cpu(bg->bg_used_dirs_count_lo) |
            (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT ?
             (__u32)le16_to_cpu(bg->bg_used_dirs_count_hi) << 16 : 0);
}

__u32 ext4_itable_unused_count(struct super_block *sb,
                        struct ext4_group_desc *bg)
{
      return le16_to_cpu(bg->bg_itable_unused_lo) |
            (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT ?
             (__u32)le16_to_cpu(bg->bg_itable_unused_hi) << 16 : 0);
}

void ext4_block_bitmap_set(struct super_block *sb,
                     struct ext4_group_desc *bg, ext4_fsblk_t blk)
{
      bg->bg_block_bitmap_lo = cpu_to_le32((u32)blk);
      if (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT)
            bg->bg_block_bitmap_hi = cpu_to_le32(blk >> 32);
}

void ext4_inode_bitmap_set(struct super_block *sb,
                     struct ext4_group_desc *bg, ext4_fsblk_t blk)
{
      bg->bg_inode_bitmap_lo  = cpu_to_le32((u32)blk);
      if (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT)
            bg->bg_inode_bitmap_hi = cpu_to_le32(blk >> 32);
}

void ext4_inode_table_set(struct super_block *sb,
                    struct ext4_group_desc *bg, ext4_fsblk_t blk)
{
      bg->bg_inode_table_lo = cpu_to_le32((u32)blk);
      if (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT)
            bg->bg_inode_table_hi = cpu_to_le32(blk >> 32);
}

void ext4_free_blks_set(struct super_block *sb,
                    struct ext4_group_desc *bg, __u32 count)
{
      bg->bg_free_blocks_count_lo = cpu_to_le16((__u16)count);
      if (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT)
            bg->bg_free_blocks_count_hi = cpu_to_le16(count >> 16);
}

void ext4_free_inodes_set(struct super_block *sb,
                    struct ext4_group_desc *bg, __u32 count)
{
      bg->bg_free_inodes_count_lo = cpu_to_le16((__u16)count);
      if (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT)
            bg->bg_free_inodes_count_hi = cpu_to_le16(count >> 16);
}

void ext4_used_dirs_set(struct super_block *sb,
                    struct ext4_group_desc *bg, __u32 count)
{
      bg->bg_used_dirs_count_lo = cpu_to_le16((__u16)count);
      if (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT)
            bg->bg_used_dirs_count_hi = cpu_to_le16(count >> 16);
}

void ext4_itable_unused_set(struct super_block *sb,
                    struct ext4_group_desc *bg, __u32 count)
{
      bg->bg_itable_unused_lo = cpu_to_le16((__u16)count);
      if (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT)
            bg->bg_itable_unused_hi = cpu_to_le16(count >> 16);
}

/*
 * Wrappers for jbd2_journal_start/end.
 *
 * The only special thing we need to do here is to make sure that all
 * journal_end calls result in the superblock being marked dirty, so
 * that sync() will call the filesystem's write_super callback if
 * appropriate.
 */
handle_t *ext4_journal_start_sb(struct super_block *sb, int nblocks)
{
      journal_t *journal;

      if (sb->s_flags & MS_RDONLY)
            return ERR_PTR(-EROFS);

      /* Special case here: if the journal has aborted behind our
       * backs (eg. EIO in the commit thread), then we still need to
       * take the FS itself readonly cleanly. */
      journal = EXT4_SB(sb)->s_journal;
      if (journal) {
            if (is_journal_aborted(journal)) {
                  ext4_abort(sb, __func__, "Detected aborted journal");
                  return ERR_PTR(-EROFS);
            }
            return jbd2_journal_start(journal, nblocks);
      }
      /*
       * We're not journaling, return the appropriate indication.
       */
      current->journal_info = EXT4_NOJOURNAL_HANDLE;
      return current->journal_info;
}

/*
 * The only special thing we need to do here is to make sure that all
 * jbd2_journal_stop calls result in the superblock being marked dirty, so
 * that sync() will call the filesystem's write_super callback if
 * appropriate.
 */
int __ext4_journal_stop(const char *where, handle_t *handle)
{
      struct super_block *sb;
      int err;
      int rc;

      if (!ext4_handle_valid(handle)) {
            /*
             * Do this here since we don't call jbd2_journal_stop() in
             * no-journal mode.
             */
            current->journal_info = NULL;
            return 0;
      }
      sb = handle->h_transaction->t_journal->j_private;
      err = handle->h_err;
      rc = jbd2_journal_stop(handle);

      if (!err)
            err = rc;
      if (err)
            __ext4_std_error(sb, where, err);
      return err;
}

void ext4_journal_abort_handle(const char *caller, const char *err_fn,
            struct buffer_head *bh, handle_t *handle, int err)
{
      char nbuf[16];
      const char *errstr = ext4_decode_error(NULL, err, nbuf);

      BUG_ON(!ext4_handle_valid(handle));

      if (bh)
            BUFFER_TRACE(bh, "abort");

      if (!handle->h_err)
            handle->h_err = err;

      if (is_handle_aborted(handle))
            return;

      printk(KERN_ERR "%s: aborting transaction: %s in %s\n",
             caller, errstr, err_fn);

      jbd2_journal_abort_handle(handle);
}

/* Deal with the reporting of failure conditions on a filesystem such as
 * inconsistencies detected or read IO failures.
 *
 * On ext2, we can store the error state of the filesystem in the
 * superblock.  That is not possible on ext4, because we may have other
 * write ordering constraints on the superblock which prevent us from
 * writing it out straight away; and given that the journal is about to
 * be aborted, we can't rely on the current, or future, transactions to
 * write out the superblock safely.
 *
 * We'll just use the jbd2_journal_abort() error code to record an error in
 * the journal instead.  On recovery, the journal will compain about
 * that error until we've noted it down and cleared it.
 */

static void ext4_handle_error(struct super_block *sb)
{
      struct ext4_super_block *es = EXT4_SB(sb)->s_es;

      EXT4_SB(sb)->s_mount_state |= EXT4_ERROR_FS;
      es->s_state |= cpu_to_le16(EXT4_ERROR_FS);

      if (sb->s_flags & MS_RDONLY)
            return;

      if (!test_opt(sb, ERRORS_CONT)) {
            journal_t *journal = EXT4_SB(sb)->s_journal;

            EXT4_SB(sb)->s_mount_flags |= EXT4_MF_FS_ABORTED;
            if (journal)
                  jbd2_journal_abort(journal, -EIO);
      }
      if (test_opt(sb, ERRORS_RO)) {
            ext4_msg(sb, KERN_CRIT, "Remounting filesystem read-only");
            sb->s_flags |= MS_RDONLY;
      }
      ext4_commit_super(sb, 1);
      if (test_opt(sb, ERRORS_PANIC))
            panic("EXT4-fs (device %s): panic forced after error\n",
                  sb->s_id);
}

void ext4_error(struct super_block *sb, const char *function,
            const char *fmt, ...)
{
      va_list args;

      va_start(args, fmt);
      printk(KERN_CRIT "EXT4-fs error (device %s): %s: ", sb->s_id, function);
      vprintk(fmt, args);
      printk("\n");
      va_end(args);

      ext4_handle_error(sb);
}

static const char *ext4_decode_error(struct super_block *sb, int errno,
                             char nbuf[16])
{
      char *errstr = NULL;

      switch (errno) {
      case -EIO:
            errstr = "IO failure";
            break;
      case -ENOMEM:
            errstr = "Out of memory";
            break;
      case -EROFS:
            if (!sb || EXT4_SB(sb)->s_journal->j_flags & JBD2_ABORT)
                  errstr = "Journal has aborted";
            else
                  errstr = "Readonly filesystem";
            break;
      default:
            /* If the caller passed in an extra buffer for unknown
             * errors, textualise them now.  Else we just return
             * NULL. */
            if (nbuf) {
                  /* Check for truncated error codes... */
                  if (snprintf(nbuf, 16, "error %d", -errno) >= 0)
                        errstr = nbuf;
            }
            break;
      }

      return errstr;
}

/* __ext4_std_error decodes expected errors from journaling functions
 * automatically and invokes the appropriate error response.  */

void __ext4_std_error(struct super_block *sb, const char *function, int errno)
{
      char nbuf[16];
      const char *errstr;

      /* Special case: if the error is EROFS, and we're not already
       * inside a transaction, then there's really no point in logging
       * an error. */
      if (errno == -EROFS && journal_current_handle() == NULL &&
          (sb->s_flags & MS_RDONLY))
            return;

      errstr = ext4_decode_error(sb, errno, nbuf);
      printk(KERN_CRIT "EXT4-fs error (device %s) in %s: %s\n",
             sb->s_id, function, errstr);

      ext4_handle_error(sb);
}

/*
 * ext4_abort is a much stronger failure handler than ext4_error.  The
 * abort function may be used to deal with unrecoverable failures such
 * as journal IO errors or ENOMEM at a critical moment in log management.
 *
 * We unconditionally force the filesystem into an ABORT|READONLY state,
 * unless the error response on the fs has been set to panic in which
 * case we take the easy way out and panic immediately.
 */

void ext4_abort(struct super_block *sb, const char *function,
            const char *fmt, ...)
{
      va_list args;

      va_start(args, fmt);
      printk(KERN_CRIT "EXT4-fs error (device %s): %s: ", sb->s_id, function);
      vprintk(fmt, args);
      printk("\n");
      va_end(args);

      if (test_opt(sb, ERRORS_PANIC))
            panic("EXT4-fs panic from previous error\n");

      if (sb->s_flags & MS_RDONLY)
            return;

      ext4_msg(sb, KERN_CRIT, "Remounting filesystem read-only");
      EXT4_SB(sb)->s_mount_state |= EXT4_ERROR_FS;
      sb->s_flags |= MS_RDONLY;
      EXT4_SB(sb)->s_mount_flags |= EXT4_MF_FS_ABORTED;
      if (EXT4_SB(sb)->s_journal)
            jbd2_journal_abort(EXT4_SB(sb)->s_journal, -EIO);
}

void ext4_msg (struct super_block * sb, const char *prefix,
               const char *fmt, ...)
{
      va_list args;

      va_start(args, fmt);
      printk("%sEXT4-fs (%s): ", prefix, sb->s_id);
      vprintk(fmt, args);
      printk("\n");
      va_end(args);
}

void ext4_warning(struct super_block *sb, const char *function,
              const char *fmt, ...)
{
      va_list args;

      va_start(args, fmt);
      printk(KERN_WARNING "EXT4-fs warning (device %s): %s: ",
             sb->s_id, function);
      vprintk(fmt, args);
      printk("\n");
      va_end(args);
}

void ext4_grp_locked_error(struct super_block *sb, ext4_group_t grp,
                     const char *function, const char *fmt, ...)
__releases(bitlock)
__acquires(bitlock)
{
      va_list args;
      struct ext4_super_block *es = EXT4_SB(sb)->s_es;

      va_start(args, fmt);
      printk(KERN_CRIT "EXT4-fs error (device %s): %s: ", sb->s_id, function);
      vprintk(fmt, args);
      printk("\n");
      va_end(args);

      if (test_opt(sb, ERRORS_CONT)) {
            EXT4_SB(sb)->s_mount_state |= EXT4_ERROR_FS;
            es->s_state |= cpu_to_le16(EXT4_ERROR_FS);
            ext4_commit_super(sb, 0);
            return;
      }
      ext4_unlock_group(sb, grp);
      ext4_handle_error(sb);
      /*
       * We only get here in the ERRORS_RO case; relocking the group
       * may be dangerous, but nothing bad will happen since the
       * filesystem will have already been marked read/only and the
       * journal has been aborted.  We return 1 as a hint to callers
       * who might what to use the return value from
       * ext4_grp_locked_error() to distinguish beween the
       * ERRORS_CONT and ERRORS_RO case, and perhaps return more
       * aggressively from the ext4 function in question, with a
       * more appropriate error code.
       */
      ext4_lock_group(sb, grp);
      return;
}

void ext4_update_dynamic_rev(struct super_block *sb)
{
      struct ext4_super_block *es = EXT4_SB(sb)->s_es;

      if (le32_to_cpu(es->s_rev_level) > EXT4_GOOD_OLD_REV)
            return;

      ext4_warning(sb, __func__,
                 "updating to rev %d because of new feature flag, "
                 "running e2fsck is recommended",
                 EXT4_DYNAMIC_REV);

      es->s_first_ino = cpu_to_le32(EXT4_GOOD_OLD_FIRST_INO);
      es->s_inode_size = cpu_to_le16(EXT4_GOOD_OLD_INODE_SIZE);
      es->s_rev_level = cpu_to_le32(EXT4_DYNAMIC_REV);
      /* leave es->s_feature_*compat flags alone */
      /* es->s_uuid will be set by e2fsck if empty */

      /*
       * The rest of the superblock fields should be zero, and if not it
       * means they are likely already in use, so leave them alone.  We
       * can leave it up to e2fsck to clean up any inconsistencies there.
       */
}

/*
 * Open the external journal device
 */
static struct block_device *ext4_blkdev_get(dev_t dev, struct super_block *sb)
{
      struct block_device *bdev;
      char b[BDEVNAME_SIZE];

      bdev = open_by_devnum(dev, FMODE_READ|FMODE_WRITE);
      if (IS_ERR(bdev))
            goto fail;
      return bdev;

fail:
      ext4_msg(sb, KERN_ERR, "failed to open journal device %s: %ld",
                  __bdevname(dev, b), PTR_ERR(bdev));
      return NULL;
}

/*
 * Release the journal device
 */
static int ext4_blkdev_put(struct block_device *bdev)
{
      bd_release(bdev);
      return blkdev_put(bdev, FMODE_READ|FMODE_WRITE);
}

static int ext4_blkdev_remove(struct ext4_sb_info *sbi)
{
      struct block_device *bdev;
      int ret = -ENODEV;

      bdev = sbi->journal_bdev;
      if (bdev) {
            ret = ext4_blkdev_put(bdev);
            sbi->journal_bdev = NULL;
      }
      return ret;
}

static inline struct inode *orphan_list_entry(struct list_head *l)
{
      return &list_entry(l, struct ext4_inode_info, i_orphan)->vfs_inode;
}

static void dump_orphan_list(struct super_block *sb, struct ext4_sb_info *sbi)
{
      struct list_head *l;

      ext4_msg(sb, KERN_ERR, "sb orphan head is %d",
             le32_to_cpu(sbi->s_es->s_last_orphan));

      printk(KERN_ERR "sb_info orphan list:\n");
      list_for_each(l, &sbi->s_orphan) {
            struct inode *inode = orphan_list_entry(l);
            printk(KERN_ERR "  "
                   "inode %s:%lu at %p: mode %o, nlink %d, next %d\n",
                   inode->i_sb->s_id, inode->i_ino, inode,
                   inode->i_mode, inode->i_nlink,
                   NEXT_ORPHAN(inode));
      }
}

static void ext4_put_super(struct super_block *sb)
{
      struct ext4_sb_info *sbi = EXT4_SB(sb);
      struct ext4_super_block *es = sbi->s_es;
      int i, err;

      lock_super(sb);
      lock_kernel();
      if (sb->s_dirt)
            ext4_commit_super(sb, 1);

      ext4_release_system_zone(sb);
      ext4_mb_release(sb);
      ext4_ext_release(sb);
      ext4_xattr_put_super(sb);
      if (sbi->s_journal) {
            err = jbd2_journal_destroy(sbi->s_journal);
            sbi->s_journal = NULL;
            if (err < 0)
                  ext4_abort(sb, __func__,
                           "Couldn't clean up the journal");
      }
      if (!(sb->s_flags & MS_RDONLY)) {
            EXT4_CLEAR_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER);
            es->s_state = cpu_to_le16(sbi->s_mount_state);
            ext4_commit_super(sb, 1);
      }
      if (sbi->s_proc) {
            remove_proc_entry(sb->s_id, ext4_proc_root);
      }
      kobject_del(&sbi->s_kobj);

      for (i = 0; i < sbi->s_gdb_count; i++)
            brelse(sbi->s_group_desc[i]);
      kfree(sbi->s_group_desc);
      if (is_vmalloc_addr(sbi->s_flex_groups))
            vfree(sbi->s_flex_groups);
      else
            kfree(sbi->s_flex_groups);
      percpu_counter_destroy(&sbi->s_freeblocks_counter);
      percpu_counter_destroy(&sbi->s_freeinodes_counter);
      percpu_counter_destroy(&sbi->s_dirs_counter);
      percpu_counter_destroy(&sbi->s_dirtyblocks_counter);
      brelse(sbi->s_sbh);
#ifdef CONFIG_QUOTA
      for (i = 0; i < MAXQUOTAS; i++)
            kfree(sbi->s_qf_names[i]);
#endif

      /* Debugging code just in case the in-memory inode orphan list
       * isn't empty.  The on-disk one can be non-empty if we've
       * detected an error and taken the fs readonly, but the
       * in-memory list had better be clean by this point. */
      if (!list_empty(&sbi->s_orphan))
            dump_orphan_list(sb, sbi);
      J_ASSERT(list_empty(&sbi->s_orphan));

      invalidate_bdev(sb->s_bdev);
      if (sbi->journal_bdev && sbi->journal_bdev != sb->s_bdev) {
            /*
             * Invalidate the journal device's buffers.  We don't want them
             * floating about in memory - the physical journal device may
             * hotswapped, and it breaks the `ro-after' testing code.
             */
            sync_blockdev(sbi->journal_bdev);
            invalidate_bdev(sbi->journal_bdev);
            ext4_blkdev_remove(sbi);
      }
      sb->s_fs_info = NULL;
      /*
       * Now that we are completely done shutting down the
       * superblock, we need to actually destroy the kobject.
       */
      unlock_kernel();
      unlock_super(sb);
      kobject_put(&sbi->s_kobj);
      wait_for_completion(&sbi->s_kobj_unregister);
      kfree(sbi->s_blockgroup_lock);
      kfree(sbi);
}

static struct kmem_cache *ext4_inode_cachep;

/*
 * Called inside transaction, so use GFP_NOFS
 */
static struct inode *ext4_alloc_inode(struct super_block *sb)
{
      struct ext4_inode_info *ei;

      ei = kmem_cache_alloc(ext4_inode_cachep, GFP_NOFS);
      if (!ei)
            return NULL;

      ei->vfs_inode.i_version = 1;
      ei->vfs_inode.i_data.writeback_index = 0;
      memset(&ei->i_cached_extent, 0, sizeof(struct ext4_ext_cache));
      INIT_LIST_HEAD(&ei->i_prealloc_list);
      spin_lock_init(&ei->i_prealloc_lock);
      /*
       * Note:  We can be called before EXT4_SB(sb)->s_journal is set,
       * therefore it can be null here.  Don't check it, just initialize
       * jinode.
       */
      jbd2_journal_init_jbd_inode(&ei->jinode, &ei->vfs_inode);
      ei->i_reserved_data_blocks = 0;
      ei->i_reserved_meta_blocks = 0;
      ei->i_allocated_meta_blocks = 0;
      ei->i_delalloc_reserved_flag = 0;
      spin_lock_init(&(ei->i_block_reservation_lock));

      return &ei->vfs_inode;
}

static void ext4_destroy_inode(struct inode *inode)
{
      if (!list_empty(&(EXT4_I(inode)->i_orphan))) {
            ext4_msg(inode->i_sb, KERN_ERR,
                   "Inode %lu (%p): orphan list check failed!",
                   inode->i_ino, EXT4_I(inode));
            print_hex_dump(KERN_INFO, "", DUMP_PREFIX_ADDRESS, 16, 4,
                        EXT4_I(inode), sizeof(struct ext4_inode_info),
                        true);
            dump_stack();
      }
      kmem_cache_free(ext4_inode_cachep, EXT4_I(inode));
}

static void init_once(void *foo)
{
      struct ext4_inode_info *ei = (struct ext4_inode_info *) foo;

      INIT_LIST_HEAD(&ei->i_orphan);
#ifdef CONFIG_EXT4_FS_XATTR
      init_rwsem(&ei->xattr_sem);
#endif
      init_rwsem(&ei->i_data_sem);
      inode_init_once(&ei->vfs_inode);
}

static int init_inodecache(void)
{
      ext4_inode_cachep = kmem_cache_create("ext4_inode_cache",
                                   sizeof(struct ext4_inode_info),
                                   0, (SLAB_RECLAIM_ACCOUNT|
                                    SLAB_MEM_SPREAD),
                                   init_once);
      if (ext4_inode_cachep == NULL)
            return -ENOMEM;
      return 0;
}

static void destroy_inodecache(void)
{
      kmem_cache_destroy(ext4_inode_cachep);
}

static void ext4_clear_inode(struct inode *inode)
{
      ext4_discard_preallocations(inode);
      if (EXT4_JOURNAL(inode))
            jbd2_journal_release_jbd_inode(EXT4_SB(inode->i_sb)->s_journal,
                               &EXT4_I(inode)->jinode);
}

static inline void ext4_show_quota_options(struct seq_file *seq,
                                 struct super_block *sb)
{
#if defined(CONFIG_QUOTA)
      struct ext4_sb_info *sbi = EXT4_SB(sb);

      if (sbi->s_jquota_fmt)
            seq_printf(seq, ",jqfmt=%s",
            (sbi->s_jquota_fmt == QFMT_VFS_OLD) ? "vfsold" : "vfsv0");

      if (sbi->s_qf_names[USRQUOTA])
            seq_printf(seq, ",usrjquota=%s", sbi->s_qf_names[USRQUOTA]);

      if (sbi->s_qf_names[GRPQUOTA])
            seq_printf(seq, ",grpjquota=%s", sbi->s_qf_names[GRPQUOTA]);

      if (sbi->s_mount_opt & EXT4_MOUNT_USRQUOTA)
            seq_puts(seq, ",usrquota");

      if (sbi->s_mount_opt & EXT4_MOUNT_GRPQUOTA)
            seq_puts(seq, ",grpquota");
#endif
}

/*
 * Show an option if
 *  - it's set to a non-default value OR
 *  - if the per-sb default is different from the global default
 */
static int ext4_show_options(struct seq_file *seq, struct vfsmount *vfs)
{
      int def_errors;
      unsigned long def_mount_opts;
      struct super_block *sb = vfs->mnt_sb;
      struct ext4_sb_info *sbi = EXT4_SB(sb);
      struct ext4_super_block *es = sbi->s_es;

      def_mount_opts = le32_to_cpu(es->s_default_mount_opts);
      def_errors     = le16_to_cpu(es->s_errors);

      if (sbi->s_sb_block != 1)
            seq_printf(seq, ",sb=%llu", sbi->s_sb_block);
      if (test_opt(sb, MINIX_DF))
            seq_puts(seq, ",minixdf");
      if (test_opt(sb, GRPID) && !(def_mount_opts & EXT4_DEFM_BSDGROUPS))
            seq_puts(seq, ",grpid");
      if (!test_opt(sb, GRPID) && (def_mount_opts & EXT4_DEFM_BSDGROUPS))
            seq_puts(seq, ",nogrpid");
      if (sbi->s_resuid != EXT4_DEF_RESUID ||
          le16_to_cpu(es->s_def_resuid) != EXT4_DEF_RESUID) {
            seq_printf(seq, ",resuid=%u", sbi->s_resuid);
      }
      if (sbi->s_resgid != EXT4_DEF_RESGID ||
          le16_to_cpu(es->s_def_resgid) != EXT4_DEF_RESGID) {
            seq_printf(seq, ",resgid=%u", sbi->s_resgid);
      }
      if (test_opt(sb, ERRORS_RO)) {
            if (def_errors == EXT4_ERRORS_PANIC ||
                def_errors == EXT4_ERRORS_CONTINUE) {
                  seq_puts(seq, ",errors=remount-ro");
            }
      }
      if (test_opt(sb, ERRORS_CONT) && def_errors != EXT4_ERRORS_CONTINUE)
            seq_puts(seq, ",errors=continue");
      if (test_opt(sb, ERRORS_PANIC) && def_errors != EXT4_ERRORS_PANIC)
            seq_puts(seq, ",errors=panic");
      if (test_opt(sb, NO_UID32) && !(def_mount_opts & EXT4_DEFM_UID16))
            seq_puts(seq, ",nouid32");
      if (test_opt(sb, DEBUG) && !(def_mount_opts & EXT4_DEFM_DEBUG))
            seq_puts(seq, ",debug");
      if (test_opt(sb, OLDALLOC))
            seq_puts(seq, ",oldalloc");
#ifdef CONFIG_EXT4_FS_XATTR
      if (test_opt(sb, XATTR_USER) &&
            !(def_mount_opts & EXT4_DEFM_XATTR_USER))
            seq_puts(seq, ",user_xattr");
      if (!test_opt(sb, XATTR_USER) &&
          (def_mount_opts & EXT4_DEFM_XATTR_USER)) {
            seq_puts(seq, ",nouser_xattr");
      }
#endif
#ifdef CONFIG_EXT4_FS_POSIX_ACL
      if (test_opt(sb, POSIX_ACL) && !(def_mount_opts & EXT4_DEFM_ACL))
            seq_puts(seq, ",acl");
      if (!test_opt(sb, POSIX_ACL) && (def_mount_opts & EXT4_DEFM_ACL))
            seq_puts(seq, ",noacl");
#endif
      if (sbi->s_commit_interval != JBD2_DEFAULT_MAX_COMMIT_AGE*HZ) {
            seq_printf(seq, ",commit=%u",
                     (unsigned) (sbi->s_commit_interval / HZ));
      }
      if (sbi->s_min_batch_time != EXT4_DEF_MIN_BATCH_TIME) {
            seq_printf(seq, ",min_batch_time=%u",
                     (unsigned) sbi->s_min_batch_time);
      }
      if (sbi->s_max_batch_time != EXT4_DEF_MAX_BATCH_TIME) {
            seq_printf(seq, ",max_batch_time=%u",
                     (unsigned) sbi->s_min_batch_time);
      }

      /*
       * We're changing the default of barrier mount option, so
       * let's always display its mount state so it's clear what its
       * status is.
       */
      seq_puts(seq, ",barrier=");
      seq_puts(seq, test_opt(sb, BARRIER) ? "1" : "0");
      if (test_opt(sb, JOURNAL_ASYNC_COMMIT))
            seq_puts(seq, ",journal_async_commit");
      if (test_opt(sb, NOBH))
            seq_puts(seq, ",nobh");
      if (test_opt(sb, I_VERSION))
            seq_puts(seq, ",i_version");
      if (!test_opt(sb, DELALLOC))
            seq_puts(seq, ",nodelalloc");


      if (sbi->s_stripe)
            seq_printf(seq, ",stripe=%lu", sbi->s_stripe);
      /*
       * journal mode get enabled in different ways
       * So just print the value even if we didn't specify it
       */
      if (test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA)
            seq_puts(seq, ",data=journal");
      else if (test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_ORDERED_DATA)
            seq_puts(seq, ",data=ordered");
      else if (test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_WRITEBACK_DATA)
            seq_puts(seq, ",data=writeback");

      if (sbi->s_inode_readahead_blks != EXT4_DEF_INODE_READAHEAD_BLKS)
            seq_printf(seq, ",inode_readahead_blks=%u",
                     sbi->s_inode_readahead_blks);

      if (test_opt(sb, DATA_ERR_ABORT))
            seq_puts(seq, ",data_err=abort");

      if (test_opt(sb, NO_AUTO_DA_ALLOC))
            seq_puts(seq, ",noauto_da_alloc");

      ext4_show_quota_options(seq, sb);

      return 0;
}

static struct inode *ext4_nfs_get_inode(struct super_block *sb,
                              u64 ino, u32 generation)
{
      struct inode *inode;

      if (ino < EXT4_FIRST_INO(sb) && ino != EXT4_ROOT_INO)
            return ERR_PTR(-ESTALE);
      if (ino > le32_to_cpu(EXT4_SB(sb)->s_es->s_inodes_count))
            return ERR_PTR(-ESTALE);

      /* iget isn't really right if the inode is currently unallocated!!
       *
       * ext4_read_inode will return a bad_inode if the inode had been
       * deleted, so we should be safe.
       *
       * Currently we don't know the generation for parent directory, so
       * a generation of 0 means "accept any"
       */
      inode = ext4_iget(sb, ino);
      if (IS_ERR(inode))
            return ERR_CAST(inode);
      if (generation && inode->i_generation != generation) {
            iput(inode);
            return ERR_PTR(-ESTALE);
      }

      return inode;
}

static struct dentry *ext4_fh_to_dentry(struct super_block *sb, struct fid *fid,
                              int fh_len, int fh_type)
{
      return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
                            ext4_nfs_get_inode);
}

static struct dentry *ext4_fh_to_parent(struct super_block *sb, struct fid *fid,
                              int fh_len, int fh_type)
{
      return generic_fh_to_parent(sb, fid, fh_len, fh_type,
                            ext4_nfs_get_inode);
}

/*
 * Try to release metadata pages (indirect blocks, directories) which are
 * mapped via the block device.  Since these pages could have journal heads
 * which would prevent try_to_free_buffers() from freeing them, we must use
 * jbd2 layer's try_to_free_buffers() function to release them.
 */
static int bdev_try_to_free_page(struct super_block *sb, struct page *page,
                         gfp_t wait)
{
      journal_t *journal = EXT4_SB(sb)->s_journal;

      WARN_ON(PageChecked(page));
      if (!page_has_buffers(page))
            return 0;
      if (journal)
            return jbd2_journal_try_to_free_buffers(journal, page,
                                          wait & ~__GFP_WAIT);
      return try_to_free_buffers(page);
}

#ifdef CONFIG_QUOTA
#define QTYPE2NAME(t) ((t) == USRQUOTA ? "user" : "group")
#define QTYPE2MOPT(on, t) ((t) == USRQUOTA?((on)##USRJQUOTA):((on)##GRPJQUOTA))

static int ext4_write_dquot(struct dquot *dquot);
static int ext4_acquire_dquot(struct dquot *dquot);
static int ext4_release_dquot(struct dquot *dquot);
static int ext4_mark_dquot_dirty(struct dquot *dquot);
static int ext4_write_info(struct super_block *sb, int type);
static int ext4_quota_on(struct super_block *sb, int type, int format_id,
                        char *path, int remount);
static int ext4_quota_on_mount(struct super_block *sb, int type);
static ssize_t ext4_quota_read(struct super_block *sb, int type, char *data,
                         size_t len, loff_t off);
static ssize_t ext4_quota_write(struct super_block *sb, int type,
                        const char *data, size_t len, loff_t off);

static struct dquot_operations ext4_quota_operations = {
      .initialize = dquot_initialize,
      .drop       = dquot_drop,
      .alloc_space      = dquot_alloc_space,
      .reserve_space    = dquot_reserve_space,
      .claim_space      = dquot_claim_space,
      .release_rsv      = dquot_release_reserved_space,
      .get_reserved_space = ext4_get_reserved_space,
      .alloc_inode      = dquot_alloc_inode,
      .free_space = dquot_free_space,
      .free_inode = dquot_free_inode,
      .transfer   = dquot_transfer,
      .write_dquot      = ext4_write_dquot,
      .acquire_dquot    = ext4_acquire_dquot,
      .release_dquot    = ext4_release_dquot,
      .mark_dirty = ext4_mark_dquot_dirty,
      .write_info = ext4_write_info,
      .alloc_dquot      = dquot_alloc,
      .destroy_dquot    = dquot_destroy,
};

static struct quotactl_ops ext4_qctl_operations = {
      .quota_on   = ext4_quota_on,
      .quota_off  = vfs_quota_off,
      .quota_sync = vfs_quota_sync,
      .get_info   = vfs_get_dqinfo,
      .set_info   = vfs_set_dqinfo,
      .get_dqblk  = vfs_get_dqblk,
      .set_dqblk  = vfs_set_dqblk
};
#endif

static const struct super_operations ext4_sops = {
      .alloc_inode      = ext4_alloc_inode,
      .destroy_inode    = ext4_destroy_inode,
      .write_inode      = ext4_write_inode,
      .dirty_inode      = ext4_dirty_inode,
      .delete_inode     = ext4_delete_inode,
      .put_super  = ext4_put_super,
      .sync_fs    = ext4_sync_fs,
      .freeze_fs  = ext4_freeze,
      .unfreeze_fs      = ext4_unfreeze,
      .statfs           = ext4_statfs,
      .remount_fs = ext4_remount,
      .clear_inode      = ext4_clear_inode,
      .show_options     = ext4_show_options,
#ifdef CONFIG_QUOTA
      .quota_read = ext4_quota_read,
      .quota_write      = ext4_quota_write,
#endif
      .bdev_try_to_free_page = bdev_try_to_free_page,
};

static const struct super_operations ext4_nojournal_sops = {
      .alloc_inode      = ext4_alloc_inode,
      .destroy_inode    = ext4_destroy_inode,
      .write_inode      = ext4_write_inode,
      .dirty_inode      = ext4_dirty_inode,
      .delete_inode     = ext4_delete_inode,
      .write_super      = ext4_write_super,
      .put_super  = ext4_put_super,
      .statfs           = ext4_statfs,
      .remount_fs = ext4_remount,
      .clear_inode      = ext4_clear_inode,
      .show_options     = ext4_show_options,
#ifdef CONFIG_QUOTA
      .quota_read = ext4_quota_read,
      .quota_write      = ext4_quota_write,
#endif
      .bdev_try_to_free_page = bdev_try_to_free_page,
};

static const struct export_operations ext4_export_ops = {
      .fh_to_dentry = ext4_fh_to_dentry,
      .fh_to_parent = ext4_fh_to_parent,
      .get_parent = ext4_get_parent,
};

enum {
      Opt_bsd_df, Opt_minix_df, Opt_grpid, Opt_nogrpid,
      Opt_resgid, Opt_resuid, Opt_sb, Opt_err_cont, Opt_err_panic, Opt_err_ro,
      Opt_nouid32, Opt_debug, Opt_oldalloc, Opt_orlov,
      Opt_user_xattr, Opt_nouser_xattr, Opt_acl, Opt_noacl,
      Opt_auto_da_alloc, Opt_noauto_da_alloc, Opt_noload, Opt_nobh, Opt_bh,
      Opt_commit, Opt_min_batch_time, Opt_max_batch_time,
      Opt_journal_update, Opt_journal_dev,
      Opt_journal_checksum, Opt_journal_async_commit,
      Opt_abort, Opt_data_journal, Opt_data_ordered, Opt_data_writeback,
      Opt_data_err_abort, Opt_data_err_ignore, Opt_mb_history_length,
      Opt_usrjquota, Opt_grpjquota, Opt_offusrjquota, Opt_offgrpjquota,
      Opt_jqfmt_vfsold, Opt_jqfmt_vfsv0, Opt_quota, Opt_noquota,
      Opt_ignore, Opt_barrier, Opt_nobarrier, Opt_err, Opt_resize,
      Opt_usrquota, Opt_grpquota, Opt_i_version,
      Opt_stripe, Opt_delalloc, Opt_nodelalloc,
      Opt_block_validity, Opt_noblock_validity,
      Opt_inode_readahead_blks, Opt_journal_ioprio
};

static const match_table_t tokens = {
      {Opt_bsd_df, "bsddf"},
      {Opt_minix_df, "minixdf"},
      {Opt_grpid, "grpid"},
      {Opt_grpid, "bsdgroups"},
      {Opt_nogrpid, "nogrpid"},
      {Opt_nogrpid, "sysvgroups"},
      {Opt_resgid, "resgid=%u"},
      {Opt_resuid, "resuid=%u"},
      {Opt_sb, "sb=%u"},
      {Opt_err_cont, "errors=continue"},
      {Opt_err_panic, "errors=panic"},
      {Opt_err_ro, "errors=remount-ro"},
      {Opt_nouid32, "nouid32"},
      {Opt_debug, "debug"},
      {Opt_oldalloc, "oldalloc"},
      {Opt_orlov, "orlov"},
      {Opt_user_xattr, "user_xattr"},
      {Opt_nouser_xattr, "nouser_xattr"},
      {Opt_acl, "acl"},
      {Opt_noacl, "noacl"},
      {Opt_noload, "noload"},
      {Opt_nobh, "nobh"},
      {Opt_bh, "bh"},
      {Opt_commit, "commit=%u"},
      {Opt_min_batch_time, "min_batch_time=%u"},
      {Opt_max_batch_time, "max_batch_time=%u"},
      {Opt_journal_update, "journal=update"},
      {Opt_journal_dev, "journal_dev=%u"},
      {Opt_journal_checksum, "journal_checksum"},
      {Opt_journal_async_commit, "journal_async_commit"},
      {Opt_abort, "abort"},
      {Opt_data_journal, "data=journal"},
      {Opt_data_ordered, "data=ordered"},
      {Opt_data_writeback, "data=writeback"},
      {Opt_data_err_abort, "data_err=abort"},
      {Opt_data_err_ignore, "data_err=ignore"},
      {Opt_mb_history_length, "mb_history_length=%u"},
      {Opt_offusrjquota, "usrjquota="},
      {Opt_usrjquota, "usrjquota=%s"},
      {Opt_offgrpjquota, "grpjquota="},
      {Opt_grpjquota, "grpjquota=%s"},
      {Opt_jqfmt_vfsold, "jqfmt=vfsold"},
      {Opt_jqfmt_vfsv0, "jqfmt=vfsv0"},
      {Opt_grpquota, "grpquota"},
      {Opt_noquota, "noquota"},
      {Opt_quota, "quota"},
      {Opt_usrquota, "usrquota"},
      {Opt_barrier, "barrier=%u"},
      {Opt_barrier, "barrier"},
      {Opt_nobarrier, "nobarrier"},
      {Opt_i_version, "i_version"},
      {Opt_stripe, "stripe=%u"},
      {Opt_resize, "resize"},
      {Opt_delalloc, "delalloc"},
      {Opt_nodelalloc, "nodelalloc"},
      {Opt_block_validity, "block_validity"},
      {Opt_noblock_validity, "noblock_validity"},
      {Opt_inode_readahead_blks, "inode_readahead_blks=%u"},
      {Opt_journal_ioprio, "journal_ioprio=%u"},
      {Opt_auto_da_alloc, "auto_da_alloc=%u"},
      {Opt_auto_da_alloc, "auto_da_alloc"},
      {Opt_noauto_da_alloc, "noauto_da_alloc"},
      {Opt_err, NULL},
};

static ext4_fsblk_t get_sb_block(void **data)
{
      ext4_fsblk_t      sb_block;
      char        *options = (char *) *data;

      if (!options || strncmp(options, "sb=", 3) != 0)
            return 1;   /* Default location */

      options += 3;
      /* TODO: use simple_strtoll with >32bit ext4 */
      sb_block = simple_strtoul(options, &options, 0);
      if (*options && *options != ',') {
            printk(KERN_ERR "EXT4-fs: Invalid sb specification: %s\n",
                   (char *) *data);
            return 1;
      }
      if (*options == ',')
            options++;
      *data = (void *) options;

      return sb_block;
}

#define DEFAULT_JOURNAL_IOPRIO (IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, 3))

static int parse_options(char *options, struct super_block *sb,
                   unsigned long *journal_devnum,
                   unsigned int *journal_ioprio,
                   ext4_fsblk_t *n_blocks_count, int is_remount)
{
      struct ext4_sb_info *sbi = EXT4_SB(sb);
      char *p;
      substring_t args[MAX_OPT_ARGS];
      int data_opt = 0;
      int option;
#ifdef CONFIG_QUOTA
      int qtype, qfmt;
      char *qname;
#endif

      if (!options)
            return 1;

      while ((p = strsep(&options, ",")) != NULL) {
            int token;
            if (!*p)
                  continue;

            token = match_token(p, tokens, args);
            switch (token) {
            case Opt_bsd_df:
                  clear_opt(sbi->s_mount_opt, MINIX_DF);
                  break;
            case Opt_minix_df:
                  set_opt(sbi->s_mount_opt, MINIX_DF);
                  break;
            case Opt_grpid:
                  set_opt(sbi->s_mount_opt, GRPID);
                  break;
            case Opt_nogrpid:
                  clear_opt(sbi->s_mount_opt, GRPID);
                  break;
            case Opt_resuid:
                  if (match_int(&args[0], &option))
                        return 0;
                  sbi->s_resuid = option;
                  break;
            case Opt_resgid:
                  if (match_int(&args[0], &option))
                        return 0;
                  sbi->s_resgid = option;
                  break;
            case Opt_sb:
                  /* handled by get_sb_block() instead of here */
                  /* *sb_block = match_int(&args[0]); */
                  break;
            case Opt_err_panic:
                  clear_opt(sbi->s_mount_opt, ERRORS_CONT);
                  clear_opt(sbi->s_mount_opt, ERRORS_RO);
                  set_opt(sbi->s_mount_opt, ERRORS_PANIC);
                  break;
            case Opt_err_ro:
                  clear_opt(sbi->s_mount_opt, ERRORS_CONT);
                  clear_opt(sbi->s_mount_opt, ERRORS_PANIC);
                  set_opt(sbi->s_mount_opt, ERRORS_RO);
                  break;
            case Opt_err_cont:
                  clear_opt(sbi->s_mount_opt, ERRORS_RO);
                  clear_opt(sbi->s_mount_opt, ERRORS_PANIC);
                  set_opt(sbi->s_mount_opt, ERRORS_CONT);
                  break;
            case Opt_nouid32:
                  set_opt(sbi->s_mount_opt, NO_UID32);
                  break;
            case Opt_debug:
                  set_opt(sbi->s_mount_opt, DEBUG);
                  break;
            case Opt_oldalloc:
                  set_opt(sbi->s_mount_opt, OLDALLOC);
                  break;
            case Opt_orlov:
                  clear_opt(sbi->s_mount_opt, OLDALLOC);
                  break;
#ifdef CONFIG_EXT4_FS_XATTR
            case Opt_user_xattr:
                  set_opt(sbi->s_mount_opt, XATTR_USER);
                  break;
            case Opt_nouser_xattr:
                  clear_opt(sbi->s_mount_opt, XATTR_USER);
                  break;
#else
            case Opt_user_xattr:
            case Opt_nouser_xattr:
                  ext4_msg(sb, KERN_ERR, "(no)user_xattr options not supported");
                  break;
#endif
#ifdef CONFIG_EXT4_FS_POSIX_ACL
            case Opt_acl:
                  set_opt(sbi->s_mount_opt, POSIX_ACL);
                  break;
            case Opt_noacl:
                  clear_opt(sbi->s_mount_opt, POSIX_ACL);
                  break;
#else
            case Opt_acl:
            case Opt_noacl:
                  ext4_msg(sb, KERN_ERR, "(no)acl options not supported");
                  break;
#endif
            case Opt_journal_update:
                  /* @@@ FIXME */
                  /* Eventually we will want to be able to create
                     a journal file here.  For now, only allow the
                     user to specify an existing inode to be the
                     journal file. */
                  if (is_remount) {
                        ext4_msg(sb, KERN_ERR,
                               "Cannot specify journal on remount");
                        return 0;
                  }
                  set_opt(sbi->s_mount_opt, UPDATE_JOURNAL);
                  break;
            case Opt_journal_dev:
                  if (is_remount) {
                        ext4_msg(sb, KERN_ERR,
                              "Cannot specify journal on remount");
                        return 0;
                  }
                  if (match_int(&args[0], &option))
                        return 0;
                  *journal_devnum = option;
                  break;
            case Opt_journal_checksum:
                  set_opt(sbi->s_mount_opt, JOURNAL_CHECKSUM);
                  break;
            case Opt_journal_async_commit:
                  set_opt(sbi->s_mount_opt, JOURNAL_ASYNC_COMMIT);
                  set_opt(sbi->s_mount_opt, JOURNAL_CHECKSUM);
                  break;
            case Opt_noload:
                  set_opt(sbi->s_mount_opt, NOLOAD);
                  break;
            case Opt_commit:
                  if (match_int(&args[0], &option))
                        return 0;
                  if (option < 0)
                        return 0;
                  if (option == 0)
                        option = JBD2_DEFAULT_MAX_COMMIT_AGE;
                  sbi->s_commit_interval = HZ * option;
                  break;
            case Opt_max_batch_time:
                  if (match_int(&args[0], &option))
                        return 0;
                  if (option < 0)
                        return 0;
                  if (option == 0)
                        option = EXT4_DEF_MAX_BATCH_TIME;
                  sbi->s_max_batch_time = option;
                  break;
            case Opt_min_batch_time:
                  if (match_int(&args[0], &option))
                        return 0;
                  if (option < 0)
                        return 0;
                  sbi->s_min_batch_time = option;
                  break;
            case Opt_data_journal:
                  data_opt = EXT4_MOUNT_JOURNAL_DATA;
                  goto datacheck;
            case Opt_data_ordered:
                  data_opt = EXT4_MOUNT_ORDERED_DATA;
                  goto datacheck;
            case Opt_data_writeback:
                  data_opt = EXT4_MOUNT_WRITEBACK_DATA;
            datacheck:
                  if (is_remount) {
                        if ((sbi->s_mount_opt & EXT4_MOUNT_DATA_FLAGS)
                                    != data_opt) {
                              ext4_msg(sb, KERN_ERR,
                                    "Cannot change data mode on remount");
                              return 0;
                        }
                  } else {
                        sbi->s_mount_opt &= ~EXT4_MOUNT_DATA_FLAGS;
                        sbi->s_mount_opt |= data_opt;
                  }
                  break;
            case Opt_data_err_abort:
                  set_opt(sbi->s_mount_opt, DATA_ERR_ABORT);
                  break;
            case Opt_data_err_ignore:
                  clear_opt(sbi->s_mount_opt, DATA_ERR_ABORT);
                  break;
            case Opt_mb_history_length:
                  if (match_int(&args[0], &option))
                        return 0;
                  if (option < 0)
                        return 0;
                  sbi->s_mb_history_max = option;
                  break;
#ifdef CONFIG_QUOTA
            case Opt_usrjquota:
                  qtype = USRQUOTA;
                  goto set_qf_name;
            case Opt_grpjquota:
                  qtype = GRPQUOTA;
set_qf_name:
                  if (sb_any_quota_loaded(sb) &&
                      !sbi->s_qf_names[qtype]) {
                        ext4_msg(sb, KERN_ERR,
                               "Cannot change journaled "
                               "quota options when quota turned on");
                        return 0;
                  }
                  qname = match_strdup(&args[0]);
                  if (!qname) {
                        ext4_msg(sb, KERN_ERR,
                              "Not enough memory for "
                              "storing quotafile name");
                        return 0;
                  }
                  if (sbi->s_qf_names[qtype] &&
                      strcmp(sbi->s_qf_names[qtype], qname)) {
                        ext4_msg(sb, KERN_ERR,
                              "%s quota file already "
                              "specified", QTYPE2NAME(qtype));
                        kfree(qname);
                        return 0;
                  }
                  sbi->s_qf_names[qtype] = qname;
                  if (strchr(sbi->s_qf_names[qtype], '/')) {
                        ext4_msg(sb, KERN_ERR,
                              "quotafile must be on "
                              "filesystem root");
                        kfree(sbi->s_qf_names[qtype]);
                        sbi->s_qf_names[qtype] = NULL;
                        return 0;
                  }
                  set_opt(sbi->s_mount_opt, QUOTA);
                  break;
            case Opt_offusrjquota:
                  qtype = USRQUOTA;
                  goto clear_qf_name;
            case Opt_offgrpjquota:
                  qtype = GRPQUOTA;
clear_qf_name:
                  if (sb_any_quota_loaded(sb) &&
                      sbi->s_qf_names[qtype]) {
                        ext4_msg(sb, KERN_ERR, "Cannot change "
                              "journaled quota options when "
                              "quota turned on");
                        return 0;
                  }
                  /*
                   * The space will be released later when all options
                   * are confirmed to be correct
                   */
                  sbi->s_qf_names[qtype] = NULL;
                  break;
            case Opt_jqfmt_vfsold:
                  qfmt = QFMT_VFS_OLD;
                  goto set_qf_format;
            case Opt_jqfmt_vfsv0:
                  qfmt = QFMT_VFS_V0;
set_qf_format:
                  if (sb_any_quota_loaded(sb) &&
                      sbi->s_jquota_fmt != qfmt) {
                        ext4_msg(sb, KERN_ERR, "Cannot change "
                              "journaled quota options when "
                              "quota turned on");
                        return 0;
                  }
                  sbi->s_jquota_fmt = qfmt;
                  break;
            case Opt_quota:
            case Opt_usrquota:
                  set_opt(sbi->s_mount_opt, QUOTA);
                  set_opt(sbi->s_mount_opt, USRQUOTA);
                  break;
            case Opt_grpquota:
                  set_opt(sbi->s_mount_opt, QUOTA);
                  set_opt(sbi->s_mount_opt, GRPQUOTA);
                  break;
            case Opt_noquota:
                  if (sb_any_quota_loaded(sb)) {
                        ext4_msg(sb, KERN_ERR, "Cannot change quota "
                              "options when quota turned on");
                        return 0;
                  }
                  clear_opt(sbi->s_mount_opt, QUOTA);
                  clear_opt(sbi->s_mount_opt, USRQUOTA);
                  clear_opt(sbi->s_mount_opt, GRPQUOTA);
                  break;
#else
            case Opt_quota:
            case Opt_usrquota:
            case Opt_grpquota:
                  ext4_msg(sb, KERN_ERR,
                        "quota options not supported");
                  break;
            case Opt_usrjquota:
            case Opt_grpjquota:
            case Opt_offusrjquota:
            case Opt_offgrpjquota:
            case Opt_jqfmt_vfsold:
            case Opt_jqfmt_vfsv0:
                  ext4_msg(sb, KERN_ERR,
                        "journaled quota options not supported");
                  break;
            case Opt_noquota:
                  break;
#endif
            case Opt_abort:
                  sbi->s_mount_flags |= EXT4_MF_FS_ABORTED;
                  break;
            case Opt_nobarrier:
                  clear_opt(sbi->s_mount_opt, BARRIER);
                  break;
            case Opt_barrier:
                  if (match_int(&args[0], &option)) {
                        set_opt(sbi->s_mount_opt, BARRIER);
                        break;
                  }
                  if (option)
                        set_opt(sbi->s_mount_opt, BARRIER);
                  else
                        clear_opt(sbi->s_mount_opt, BARRIER);
                  break;
            case Opt_ignore:
                  break;
            case Opt_resize:
                  if (!is_remount) {
                        ext4_msg(sb, KERN_ERR,
                              "resize option only available "
                              "for remount");
                        return 0;
                  }
                  if (match_int(&args[0], &option) != 0)
                        return 0;
                  *n_blocks_count = option;
                  break;
            case Opt_nobh:
                  set_opt(sbi->s_mount_opt, NOBH);
                  break;
            case Opt_bh:
                  clear_opt(sbi->s_mount_opt, NOBH);
                  break;
            case Opt_i_version:
                  set_opt(sbi->s_mount_opt, I_VERSION);
                  sb->s_flags |= MS_I_VERSION;
                  break;
            case Opt_nodelalloc:
                  clear_opt(sbi->s_mount_opt, DELALLOC);
                  break;
            case Opt_stripe:
                  if (match_int(&args[0], &option))
                        return 0;
                  if (option < 0)
                        return 0;
                  sbi->s_stripe = option;
                  break;
            case Opt_delalloc:
                  set_opt(sbi->s_mount_opt, DELALLOC);
                  break;
            case Opt_block_validity:
                  set_opt(sbi->s_mount_opt, BLOCK_VALIDITY);
                  break;
            case Opt_noblock_validity:
                  clear_opt(sbi->s_mount_opt, BLOCK_VALIDITY);
                  break;
            case Opt_inode_readahead_blks:
                  if (match_int(&args[0], &option))
                        return 0;
                  if (option < 0 || option > (1 << 30))
                        return 0;
                  if (!is_power_of_2(option)) {
                        ext4_msg(sb, KERN_ERR,
                               "EXT4-fs: inode_readahead_blks"
                               " must be a power of 2");
                        return 0;
                  }
                  sbi->s_inode_readahead_blks = option;
                  break;
            case Opt_journal_ioprio:
                  if (match_int(&args[0], &option))
                        return 0;
                  if (option < 0 || option > 7)
                        break;
                  *journal_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE,
                                              option);
                  break;
            case Opt_noauto_da_alloc:
                  set_opt(sbi->s_mount_opt,NO_AUTO_DA_ALLOC);
                  break;
            case Opt_auto_da_alloc:
                  if (match_int(&args[0], &option)) {
                        clear_opt(sbi->s_mount_opt, NO_AUTO_DA_ALLOC);
                        break;
                  }
                  if (option)
                        clear_opt(sbi->s_mount_opt, NO_AUTO_DA_ALLOC);
                  else
                        set_opt(sbi->s_mount_opt,NO_AUTO_DA_ALLOC);
                  break;
            default:
                  ext4_msg(sb, KERN_ERR,
                         "Unrecognized mount option \"%s\" "
                         "or missing value", p);
                  return 0;
            }
      }
#ifdef CONFIG_QUOTA
      if (sbi->s_qf_names[USRQUOTA] || sbi->s_qf_names[GRPQUOTA]) {
            if ((sbi->s_mount_opt & EXT4_MOUNT_USRQUOTA) &&
                 sbi->s_qf_names[USRQUOTA])
                  clear_opt(sbi->s_mount_opt, USRQUOTA);

            if ((sbi->s_mount_opt & EXT4_MOUNT_GRPQUOTA) &&
                 sbi->s_qf_names[GRPQUOTA])
                  clear_opt(sbi->s_mount_opt, GRPQUOTA);

            if ((sbi->s_qf_names[USRQUOTA] &&
                        (sbi->s_mount_opt & EXT4_MOUNT_GRPQUOTA)) ||
                (sbi->s_qf_names[GRPQUOTA] &&
                        (sbi->s_mount_opt & EXT4_MOUNT_USRQUOTA))) {
                  ext4_msg(sb, KERN_ERR, "old and new quota "
                              "format mixing");
                  return 0;
            }

            if (!sbi->s_jquota_fmt) {
                  ext4_msg(sb, KERN_ERR, "journaled quota format "
                              "not specified");
                  return 0;
            }
      } else {
            if (sbi->s_jquota_fmt) {
                  ext4_msg(sb, KERN_ERR, "journaled quota format "
                              "specified with no journaling "
                              "enabled");
                  return 0;
            }
      }
#endif
      return 1;
}

static int ext4_setup_super(struct super_block *sb, struct ext4_super_block *es,
                      int read_only)
{
      struct ext4_sb_info *sbi = EXT4_SB(sb);
      int res = 0;

      if (le32_to_cpu(es->s_rev_level) > EXT4_MAX_SUPP_REV) {
            ext4_msg(sb, KERN_ERR, "revision level too high, "
                   "forcing read-only mode");
            res = MS_RDONLY;
      }
      if (read_only)
            return res;
      if (!(sbi->s_mount_state & EXT4_VALID_FS))
            ext4_msg(sb, KERN_WARNING, "warning: mounting unchecked fs, "
                   "running e2fsck is recommended");
      else if ((sbi->s_mount_state & EXT4_ERROR_FS))
            ext4_msg(sb, KERN_WARNING,
                   "warning: mounting fs with errors, "
                   "running e2fsck is recommended");
      else if ((__s16) le16_to_cpu(es->s_max_mnt_count) >= 0 &&
             le16_to_cpu(es->s_mnt_count) >=
             (unsigned short) (__s16) le16_to_cpu(es->s_max_mnt_count))
            ext4_msg(sb, KERN_WARNING,
                   "warning: maximal mount count reached, "
                   "running e2fsck is recommended");
      else if (le32_to_cpu(es->s_checkinterval) &&
            (le32_to_cpu(es->s_lastcheck) +
                  le32_to_cpu(es->s_checkinterval) <= get_seconds()))
            ext4_msg(sb, KERN_WARNING,
                   "warning: checktime reached, "
                   "running e2fsck is recommended");
      if (!sbi->s_journal)
            es->s_state &= cpu_to_le16(~EXT4_VALID_FS);
      if (!(__s16) le16_to_cpu(es->s_max_mnt_count))
            es->s_max_mnt_count = cpu_to_le16(EXT4_DFL_MAX_MNT_COUNT);
      le16_add_cpu(&es->s_mnt_count, 1);
      es->s_mtime = cpu_to_le32(get_seconds());
      ext4_update_dynamic_rev(sb);
      if (sbi->s_journal)
            EXT4_SET_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER);

      ext4_commit_super(sb, 1);
      if (test_opt(sb, DEBUG))
            printk(KERN_INFO "[EXT4 FS bs=%lu, gc=%u, "
                        "bpg=%lu, ipg=%lu, mo=%04x]\n",
                  sb->s_blocksize,
                  sbi->s_groups_count,
                  EXT4_BLOCKS_PER_GROUP(sb),
                  EXT4_INODES_PER_GROUP(sb),
                  sbi->s_mount_opt);

      if (EXT4_SB(sb)->s_journal) {
            ext4_msg(sb, KERN_INFO, "%s journal on %s",
                   EXT4_SB(sb)->s_journal->j_inode ? "internal" :
                   "external", EXT4_SB(sb)->s_journal->j_devname);
      } else {
            ext4_msg(sb, KERN_INFO, "no journal");
      }
      return res;
}

static int ext4_fill_flex_info(struct super_block *sb)
{
      struct ext4_sb_info *sbi = EXT4_SB(sb);
      struct ext4_group_desc *gdp = NULL;
      ext4_group_t flex_group_count;
      ext4_group_t flex_group;
      int groups_per_flex = 0;
      size_t size;
      int i;

      if (!sbi->s_es->s_log_groups_per_flex) {
            sbi->s_log_groups_per_flex = 0;
            return 1;
      }

      sbi->s_log_groups_per_flex = sbi->s_es->s_log_groups_per_flex;
      groups_per_flex = 1 << sbi->s_log_groups_per_flex;

      /* We allocate both existing and potentially added groups */
      flex_group_count = ((sbi->s_groups_count + groups_per_flex - 1) +
                  ((le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks) + 1) <<
                        EXT4_DESC_PER_BLOCK_BITS(sb))) / groups_per_flex;
      size = flex_group_count * sizeof(struct flex_groups);
      sbi->s_flex_groups = kzalloc(size, GFP_KERNEL);
      if (sbi->s_flex_groups == NULL) {
            sbi->s_flex_groups = vmalloc(size);
            if (sbi->s_flex_groups)
                  memset(sbi->s_flex_groups, 0, size);
      }
      if (sbi->s_flex_groups == NULL) {
            ext4_msg(sb, KERN_ERR, "not enough memory for "
                        "%u flex groups", flex_group_count);
            goto failed;
      }

      for (i = 0; i < sbi->s_groups_count; i++) {
            gdp = ext4_get_group_desc(sb, i, NULL);

            flex_group = ext4_flex_group(sbi, i);
            atomic_set(&sbi->s_flex_groups[flex_group].free_inodes,
                     ext4_free_inodes_count(sb, gdp));
            atomic_set(&sbi->s_flex_groups[flex_group].free_blocks,
                     ext4_free_blks_count(sb, gdp));
            atomic_set(&sbi->s_flex_groups[flex_group].used_dirs,
                     ext4_used_dirs_count(sb, gdp));
      }

      return 1;
failed:
      return 0;
}

__le16 ext4_group_desc_csum(struct ext4_sb_info *sbi, __u32 block_group,
                      struct ext4_group_desc *gdp)
{
      __u16 crc = 0;

      if (sbi->s_es->s_feature_ro_compat &
          cpu_to_le32(EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) {
            int offset = offsetof(struct ext4_group_desc, bg_checksum);
            __le32 le_group = cpu_to_le32(block_group);

            crc = crc16(~0, sbi->s_es->s_uuid, sizeof(sbi->s_es->s_uuid));
            crc = crc16(crc, (__u8 *)&le_group, sizeof(le_group));
            crc = crc16(crc, (__u8 *)gdp, offset);
            offset += sizeof(gdp->bg_checksum); /* skip checksum */
            /* for checksum of struct ext4_group_desc do the rest...*/
            if ((sbi->s_es->s_feature_incompat &
                 cpu_to_le32(EXT4_FEATURE_INCOMPAT_64BIT)) &&
                offset < le16_to_cpu(sbi->s_es->s_desc_size))
                  crc = crc16(crc, (__u8 *)gdp + offset,
                            le16_to_cpu(sbi->s_es->s_desc_size) -
                              offset);
      }

      return cpu_to_le16(crc);
}

int ext4_group_desc_csum_verify(struct ext4_sb_info *sbi, __u32 block_group,
                        struct ext4_group_desc *gdp)
{
      if ((sbi->s_es->s_feature_ro_compat &
           cpu_to_le32(EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) &&
          (gdp->bg_checksum != ext4_group_desc_csum(sbi, block_group, gdp)))
            return 0;

      return 1;
}

/* Called at mount-time, super-block is locked */
static int ext4_check_descriptors(struct super_block *sb)
{
      struct ext4_sb_info *sbi = EXT4_SB(sb);
      ext4_fsblk_t first_block = le32_to_cpu(sbi->s_es->s_first_data_block);
      ext4_fsblk_t last_block;
      ext4_fsblk_t block_bitmap;
      ext4_fsblk_t inode_bitmap;
      ext4_fsblk_t inode_table;
      int flexbg_flag = 0;
      ext4_group_t i;

      if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG))
            flexbg_flag = 1;

      ext4_debug("Checking group descriptors");

      for (i = 0; i < sbi->s_groups_count; i++) {
            struct ext4_group_desc *gdp = ext4_get_group_desc(sb, i, NULL);

            if (i == sbi->s_groups_count - 1 || flexbg_flag)
                  last_block = ext4_blocks_count(sbi->s_es) - 1;
            else
                  last_block = first_block +
                        (EXT4_BLOCKS_PER_GROUP(sb) - 1);

            block_bitmap = ext4_block_bitmap(sb, gdp);
            if (block_bitmap < first_block || block_bitmap > last_block) {
                  ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
                         "Block bitmap for group %u not in group "
                         "(block %llu)!", i, block_bitmap);
                  return 0;
            }
            inode_bitmap = ext4_inode_bitmap(sb, gdp);
            if (inode_bitmap < first_block || inode_bitmap > last_block) {
                  ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
                         "Inode bitmap for group %u not in group "
                         "(block %llu)!", i, inode_bitmap);
                  return 0;
            }
            inode_table = ext4_inode_table(sb, gdp);
            if (inode_table < first_block ||
                inode_table + sbi->s_itb_per_group - 1 > last_block) {
                  ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
                         "Inode table for group %u not in group "
                         "(block %llu)!", i, inode_table);
                  return 0;
            }
            ext4_lock_group(sb, i);
            if (!ext4_group_desc_csum_verify(sbi, i, gdp)) {
                  ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
                         "Checksum for group %u failed (%u!=%u)",
                         i, le16_to_cpu(ext4_group_desc_csum(sbi, i,
                             gdp)), le16_to_cpu(gdp->bg_checksum));
                  if (!(sb->s_flags & MS_RDONLY)) {
                        ext4_unlock_group(sb, i);
                        return 0;
                  }
            }
            ext4_unlock_group(sb, i);
            if (!flexbg_flag)
                  first_block += EXT4_BLOCKS_PER_GROUP(sb);
      }

      ext4_free_blocks_count_set(sbi->s_es, ext4_count_free_blocks(sb));
      sbi->s_es->s_free_inodes_count =cpu_to_le32(ext4_count_free_inodes(sb));
      return 1;
}

/* ext4_orphan_cleanup() walks a singly-linked list of inodes (starting at
 * the superblock) which were deleted from all directories, but held open by
 * a process at the time of a crash.  We walk the list and try to delete these
 * inodes at recovery time (only with a read-write filesystem).
 *
 * In order to keep the orphan inode chain consistent during traversal (in
 * case of crash during recovery), we link each inode into the superblock
 * orphan list_head and handle it the same way as an inode deletion during
 * normal operation (which journals the operations for us).
 *
 * We only do an iget() and an iput() on each inode, which is very safe if we
 * accidentally point at an in-use or already deleted inode.  The worst that
 * can happen in this case is that we get a "bit already cleared" message from
 * ext4_free_inode().  The only reason we would point at a wrong inode is if
 * e2fsck was run on this filesystem, and it must have already done the orphan
 * inode cleanup for us, so we can safely abort without any further action.
 */
static void ext4_orphan_cleanup(struct super_block *sb,
                        struct ext4_super_block *es)
{
      unsigned int s_flags = sb->s_flags;
      int nr_orphans = 0, nr_truncates = 0;
#ifdef CONFIG_QUOTA
      int i;
#endif
      if (!es->s_last_orphan) {
            jbd_debug(4, "no orphan inodes to clean up\n");
            return;
      }

      if (bdev_read_only(sb->s_bdev)) {
            ext4_msg(sb, KERN_ERR, "write access "
                  "unavailable, skipping orphan cleanup");
            return;
      }

      if (EXT4_SB(sb)->s_mount_state & EXT4_ERROR_FS) {
            if (es->s_last_orphan)
                  jbd_debug(1, "Errors on filesystem, "
                          "clearing orphan list.\n");
            es->s_last_orphan = 0;
            jbd_debug(1, "Skipping orphan recovery on fs with errors.\n");
            return;
      }

      if (s_flags & MS_RDONLY) {
            ext4_msg(sb, KERN_INFO, "orphan cleanup on readonly fs");
            sb->s_flags &= ~MS_RDONLY;
      }
#ifdef CONFIG_QUOTA
      /* Needed for iput() to work correctly and not trash data */
      sb->s_flags |= MS_ACTIVE;
      /* Turn on quotas so that they are updated correctly */
      for (i = 0; i < MAXQUOTAS; i++) {
            if (EXT4_SB(sb)->s_qf_names[i]) {
                  int ret = ext4_quota_on_mount(sb, i);
                  if (ret < 0)
                        ext4_msg(sb, KERN_ERR,
                              "Cannot turn on journaled "
                              "quota: error %d", ret);
            }
      }
#endif

      while (es->s_last_orphan) {
            struct inode *inode;

            inode = ext4_orphan_get(sb, le32_to_cpu(es->s_last_orphan));
            if (IS_ERR(inode)) {
                  es->s_last_orphan = 0;
                  break;
            }

            list_add(&EXT4_I(inode)->i_orphan, &EXT4_SB(sb)->s_orphan);
            vfs_dq_init(inode);
            if (inode->i_nlink) {
                  ext4_msg(sb, KERN_DEBUG,
                        "%s: truncating inode %lu to %lld bytes",
                        __func__, inode->i_ino, inode->i_size);
                  jbd_debug(2, "truncating inode %lu to %lld bytes\n",
                          inode->i_ino, inode->i_size);
                  ext4_truncate(inode);
                  nr_truncates++;
            } else {
                  ext4_msg(sb, KERN_DEBUG,
                        "%s: deleting unreferenced inode %lu",
                        __func__, inode->i_ino);
                  jbd_debug(2, "deleting unreferenced inode %lu\n",
                          inode->i_ino);
                  nr_orphans++;
            }
            iput(inode);  /* The delete magic happens here! */
      }

#define PLURAL(x) (x), ((x) == 1) ? "" : "s"

      if (nr_orphans)
            ext4_msg(sb, KERN_INFO, "%d orphan inode%s deleted",
                   PLURAL(nr_orphans));
      if (nr_truncates)
            ext4_msg(sb, KERN_INFO, "%d truncate%s cleaned up",
                   PLURAL(nr_truncates));
#ifdef CONFIG_QUOTA
      /* Turn quotas off */
      for (i = 0; i < MAXQUOTAS; i++) {
            if (sb_dqopt(sb)->files[i])
                  vfs_quota_off(sb, i, 0);
      }
#endif
      sb->s_flags = s_flags; /* Restore MS_RDONLY status */
}

/*
 * Maximal extent format file size.
 * Resulting logical blkno at s_maxbytes must fit in our on-disk
 * extent format containers, within a sector_t, and within i_blocks
 * in the vfs.  ext4 inode has 48 bits of i_block in fsblock units,
 * so that won't be a limiting factor.
 *
 * Note, this does *not* consider any metadata overhead for vfs i_blocks.
 */
static loff_t ext4_max_size(int blkbits, int has_huge_files)
{
      loff_t res;
      loff_t upper_limit = MAX_LFS_FILESIZE;

      /* small i_blocks in vfs inode? */
      if (!has_huge_files || sizeof(blkcnt_t) < sizeof(u64)) {
            /*
             * CONFIG_LBDAF is not enabled implies the inode
             * i_block represent total blocks in 512 bytes
             * 32 == size of vfs inode i_blocks * 8
             */
            upper_limit = (1LL << 32) - 1;

            /* total blocks in file system block size */
            upper_limit >>= (blkbits - 9);
            upper_limit <<= blkbits;
      }

      /* 32-bit extent-start container, ee_block */
      res = 1LL << 32;
      res <<= blkbits;
      res -= 1;

      /* Sanity check against vm- & vfs- imposed limits */
      if (res > upper_limit)
            res = upper_limit;

      return res;
}

/*
 * Maximal bitmap file size.  There is a direct, and {,double-,triple-}indirect
 * block limit, and also a limit of (2^48 - 1) 512-byte sectors in i_blocks.
 * We need to be 1 filesystem block less than the 2^48 sector limit.
 */
static loff_t ext4_max_bitmap_size(int bits, int has_huge_files)
{
      loff_t res = EXT4_NDIR_BLOCKS;
      int meta_blocks;
      loff_t upper_limit;
      /* This is calculated to be the largest file size for a dense, block
       * mapped file such that the file's total number of 512-byte sectors,
       * including data and all indirect blocks, does not exceed (2^48 - 1).
       *
       * __u32 i_blocks_lo and _u16 i_blocks_high represent the total
       * number of 512-byte sectors of the file.
       */

      if (!has_huge_files || sizeof(blkcnt_t) < sizeof(u64)) {
            /*
             * !has_huge_files or CONFIG_LBDAF not enabled implies that
             * the inode i_block field represents total file blocks in
             * 2^32 512-byte sectors == size of vfs inode i_blocks * 8
             */
            upper_limit = (1LL << 32) - 1;

            /* total blocks in file system block size */
            upper_limit >>= (bits - 9);

      } else {
            /*
             * We use 48 bit ext4_inode i_blocks
             * With EXT4_HUGE_FILE_FL set the i_blocks
             * represent total number of blocks in
             * file system block size
             */
            upper_limit = (1LL << 48) - 1;

      }

      /* indirect blocks */
      meta_blocks = 1;
      /* double indirect blocks */
      meta_blocks += 1 + (1LL << (bits-2));
      /* tripple indirect blocks */
      meta_blocks += 1 + (1LL << (bits-2)) + (1LL << (2*(bits-2)));

      upper_limit -= meta_blocks;
      upper_limit <<= bits;

      res += 1LL << (bits-2);
      res += 1LL << (2*(bits-2));
      res += 1LL << (3*(bits-2));
      res <<= bits;
      if (res > upper_limit)
            res = upper_limit;

      if (res > MAX_LFS_FILESIZE)
            res = MAX_LFS_FILESIZE;

      return res;
}

static ext4_fsblk_t descriptor_loc(struct super_block *sb,
                           ext4_fsblk_t logical_sb_block, int nr)
{
      struct ext4_sb_info *sbi = EXT4_SB(sb);
      ext4_group_t bg, first_meta_bg;
      int has_super = 0;

      first_meta_bg = le32_to_cpu(sbi->s_es->s_first_meta_bg);

      if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) ||
          nr < first_meta_bg)
            return logical_sb_block + nr + 1;
      bg = sbi->s_desc_per_block * nr;
      if (ext4_bg_has_super(sb, bg))
            has_super = 1;

      return (has_super + ext4_group_first_block_no(sb, bg));
}

/**
 * ext4_get_stripe_size: Get the stripe size.
 * @sbi: In memory super block info
 *
 * If we have specified it via mount option, then
 * use the mount option value. If the value specified at mount time is
 * greater than the blocks per group use the super block value.
 * If the super block value is greater than blocks per group return 0.
 * Allocator needs it be less than blocks per group.
 *
 */
static unsigned long ext4_get_stripe_size(struct ext4_sb_info *sbi)
{
      unsigned long stride = le16_to_cpu(sbi->s_es->s_raid_stride);
      unsigned long stripe_width =
                  le32_to_cpu(sbi->s_es->s_raid_stripe_width);

      if (sbi->s_stripe && sbi->s_stripe <= sbi->s_blocks_per_group)
            return sbi->s_stripe;

      if (stripe_width <= sbi->s_blocks_per_group)
            return stripe_width;

      if (stride <= sbi->s_blocks_per_group)
            return stride;

      return 0;
}

/* sysfs supprt */

02082 struct ext4_attr {
      struct attribute attr;
      ssize_t (*show)(struct ext4_attr *, struct ext4_sb_info *, char *);
      ssize_t (*store)(struct ext4_attr *, struct ext4_sb_info *, 
                   const char *, size_t);
      int offset;
};

static int parse_strtoul(const char *buf,
            unsigned long max, unsigned long *value)
{
      char *endp;

      while (*buf && isspace(*buf))
            buf++;
      *value = simple_strtoul(buf, &endp, 0);
      while (*endp && isspace(*endp))
            endp++;
      if (*endp || *value > max)
            return -EINVAL;

      return 0;
}

static ssize_t delayed_allocation_blocks_show(struct ext4_attr *a,
                                    struct ext4_sb_info *sbi,
                                    char *buf)
{
      return snprintf(buf, PAGE_SIZE, "%llu\n",
                  (s64) percpu_counter_sum(&sbi->s_dirtyblocks_counter));
}

static ssize_t session_write_kbytes_show(struct ext4_attr *a,
                               struct ext4_sb_info *sbi, char *buf)
{
      struct super_block *sb = sbi->s_buddy_cache->i_sb;

      return snprintf(buf, PAGE_SIZE, "%lu\n",
                  (part_stat_read(sb->s_bdev->bd_part, sectors[1]) -
                   sbi->s_sectors_written_start) >> 1);
}

static ssize_t lifetime_write_kbytes_show(struct ext4_attr *a,
                                struct ext4_sb_info *sbi, char *buf)
{
      struct super_block *sb = sbi->s_buddy_cache->i_sb;

      return snprintf(buf, PAGE_SIZE, "%llu\n",
                  sbi->s_kbytes_written + 
                  ((part_stat_read(sb->s_bdev->bd_part, sectors[1]) -
                    EXT4_SB(sb)->s_sectors_written_start) >> 1));
}

static ssize_t inode_readahead_blks_store(struct ext4_attr *a,
                                struct ext4_sb_info *sbi,
                                const char *buf, size_t count)
{
      unsigned long t;

      if (parse_strtoul(buf, 0x40000000, &t))
            return -EINVAL;

      if (!is_power_of_2(t))
            return -EINVAL;

      sbi->s_inode_readahead_blks = t;
      return count;
}

static ssize_t sbi_ui_show(struct ext4_attr *a,
                     struct ext4_sb_info *sbi, char *buf)
{
      unsigned int *ui = (unsigned int *) (((char *) sbi) + a->offset);

      return snprintf(buf, PAGE_SIZE, "%u\n", *ui);
}

static ssize_t sbi_ui_store(struct ext4_attr *a,
                      struct ext4_sb_info *sbi,
                      const char *buf, size_t count)
{
      unsigned int *ui = (unsigned int *) (((char *) sbi) + a->offset);
      unsigned long t;

      if (parse_strtoul(buf, 0xffffffff, &t))
            return -EINVAL;
      *ui = t;
      return count;
}

#define EXT4_ATTR_OFFSET(_name,_mode,_show,_store,_elname) \
static struct ext4_attr ext4_attr_##_name = {               \
      .attr = {.name = __stringify(_name), .mode = _mode }, \
      .show = _show,                            \
      .store      = _store,                           \
      .offset = offsetof(struct ext4_sb_info, _elname),     \
}
#define EXT4_ATTR(name, mode, show, store) \
static struct ext4_attr ext4_attr_##name = __ATTR(name, mode, show, store)

#define EXT4_RO_ATTR(name) EXT4_ATTR(name, 0444, name##_show, NULL)
#define EXT4_RW_ATTR(name) EXT4_ATTR(name, 0644, name##_show, name##_store)
#define EXT4_RW_ATTR_SBI_UI(name, elname) \
      EXT4_ATTR_OFFSET(name, 0644, sbi_ui_show, sbi_ui_store, elname)
#define ATTR_LIST(name) &ext4_attr_##name.attr

EXT4_RO_ATTR(delayed_allocation_blocks);
EXT4_RO_ATTR(session_write_kbytes);
EXT4_RO_ATTR(lifetime_write_kbytes);
EXT4_ATTR_OFFSET(inode_readahead_blks, 0644, sbi_ui_show,
             inode_readahead_blks_store, s_inode_readahead_blks);
EXT4_RW_ATTR_SBI_UI(inode_goal, s_inode_goal);
EXT4_RW_ATTR_SBI_UI(mb_stats, s_mb_stats);
EXT4_RW_ATTR_SBI_UI(mb_max_to_scan, s_mb_max_to_scan);
EXT4_RW_ATTR_SBI_UI(mb_min_to_scan, s_mb_min_to_scan);
EXT4_RW_ATTR_SBI_UI(mb_order2_req, s_mb_order2_reqs);
EXT4_RW_ATTR_SBI_UI(mb_stream_req, s_mb_stream_request);
EXT4_RW_ATTR_SBI_UI(mb_group_prealloc, s_mb_group_prealloc);

static struct attribute *ext4_attrs[] = {
      ATTR_LIST(delayed_allocation_blocks),
      ATTR_LIST(session_write_kbytes),
      ATTR_LIST(lifetime_write_kbytes),
      ATTR_LIST(inode_readahead_blks),
      ATTR_LIST(inode_goal),
      ATTR_LIST(mb_stats),
      ATTR_LIST(mb_max_to_scan),
      ATTR_LIST(mb_min_to_scan),
      ATTR_LIST(mb_order2_req),
      ATTR_LIST(mb_stream_req),
      ATTR_LIST(mb_group_prealloc),
      NULL,
};

static ssize_t ext4_attr_show(struct kobject *kobj,
                        struct attribute *attr, char *buf)
{
      struct ext4_sb_info *sbi = container_of(kobj, struct ext4_sb_info,
                                    s_kobj);
      struct ext4_attr *a = container_of(attr, struct ext4_attr, attr);

      return a->show ? a->show(a, sbi, buf) : 0;
}

static ssize_t ext4_attr_store(struct kobject *kobj,
                         struct attribute *attr,
                         const char *buf, size_t len)
{
      struct ext4_sb_info *sbi = container_of(kobj, struct ext4_sb_info,
                                    s_kobj);
      struct ext4_attr *a = container_of(attr, struct ext4_attr, attr);

      return a->store ? a->store(a, sbi, buf, len) : 0;
}

static void ext4_sb_release(struct kobject *kobj)
{
      struct ext4_sb_info *sbi = container_of(kobj, struct ext4_sb_info,
                                    s_kobj);
      complete(&sbi->s_kobj_unregister);
}


static struct sysfs_ops ext4_attr_ops = {
      .show = ext4_attr_show,
      .store      = ext4_attr_store,
};

static struct kobj_type ext4_ktype = {
      .default_attrs    = ext4_attrs,
      .sysfs_ops  = &ext4_attr_ops,
      .release    = ext4_sb_release,
};

static int ext4_fill_super(struct super_block *sb, void *data, int silent)
                        __releases(kernel_lock)
                        __acquires(kernel_lock)
{
      struct buffer_head *bh;
      struct ext4_super_block *es = NULL;
      struct ext4_sb_info *sbi;
      ext4_fsblk_t block;
      ext4_fsblk_t sb_block = get_sb_block(&data);
      ext4_fsblk_t logical_sb_block;
      unsigned long offset = 0;
      unsigned long journal_devnum = 0;
      unsigned long def_mount_opts;
      struct inode *root;
      char *cp;
      const char *descr;
      int ret = -EINVAL;
      int blocksize;
      unsigned int db_count;
      unsigned int i;
      int needs_recovery, has_huge_files;
      int features;
      __u64 blocks_count;
      int err;
      unsigned int journal_ioprio = DEFAULT_JOURNAL_IOPRIO;

      sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
      if (!sbi)
            return -ENOMEM;

      sbi->s_blockgroup_lock =
            kzalloc(sizeof(struct blockgroup_lock), GFP_KERNEL);
      if (!sbi->s_blockgroup_lock) {
            kfree(sbi);
            return -ENOMEM;
      }
      sb->s_fs_info = sbi;
      sbi->s_mount_opt = 0;
      sbi->s_resuid = EXT4_DEF_RESUID;
      sbi->s_resgid = EXT4_DEF_RESGID;
      sbi->s_inode_readahead_blks = EXT4_DEF_INODE_READAHEAD_BLKS;
      sbi->s_sb_block = sb_block;
      sbi->s_sectors_written_start = part_stat_read(sb->s_bdev->bd_part,
                                          sectors[1]);

      unlock_kernel();

      /* Cleanup superblock name */
      for (cp = sb->s_id; (cp = strchr(cp, '/'));)
            *cp = '!';

      blocksize = sb_min_blocksize(sb, EXT4_MIN_BLOCK_SIZE);
      if (!blocksize) {
            ext4_msg(sb, KERN_ERR, "unable to set blocksize");
            goto out_fail;
      }

      /*
       * The ext4 superblock will not be buffer aligned for other than 1kB
       * block sizes.  We need to calculate the offset from buffer start.
       */
      if (blocksize != EXT4_MIN_BLOCK_SIZE) {
            logical_sb_block = sb_block * EXT4_MIN_BLOCK_SIZE;
            offset = do_div(logical_sb_block, blocksize);
      } else {
            logical_sb_block = sb_block;
      }

      if (!(bh = sb_bread(sb, logical_sb_block))) {
            ext4_msg(sb, KERN_ERR, "unable to read superblock");
            goto out_fail;
      }
      /*
       * Note: s_es must be initialized as soon as possible because
       *       some ext4 macro-instructions depend on its value
       */
      es = (struct ext4_super_block *) (((char *)bh->b_data) + offset);
      sbi->s_es = es;
      sb->s_magic = le16_to_cpu(es->s_magic);
      if (sb->s_magic != EXT4_SUPER_MAGIC)
            goto cantfind_ext4;
      sbi->s_kbytes_written = le64_to_cpu(es->s_kbytes_written);

      /* Set defaults before we parse the mount options */
      def_mount_opts = le32_to_cpu(es->s_default_mount_opts);
      if (def_mount_opts & EXT4_DEFM_DEBUG)
            set_opt(sbi->s_mount_opt, DEBUG);
      if (def_mount_opts & EXT4_DEFM_BSDGROUPS)
            set_opt(sbi->s_mount_opt, GRPID);
      if (def_mount_opts & EXT4_DEFM_UID16)
            set_opt(sbi->s_mount_opt, NO_UID32);
#ifdef CONFIG_EXT4_FS_XATTR
      if (def_mount_opts & EXT4_DEFM_XATTR_USER)
            set_opt(sbi->s_mount_opt, XATTR_USER);
#endif
#ifdef CONFIG_EXT4_FS_POSIX_ACL
      if (def_mount_opts & EXT4_DEFM_ACL)
            set_opt(sbi->s_mount_opt, POSIX_ACL);
#endif
      if ((def_mount_opts & EXT4_DEFM_JMODE) == EXT4_DEFM_JMODE_DATA)
            sbi->s_mount_opt |= EXT4_MOUNT_JOURNAL_DATA;
      else if ((def_mount_opts & EXT4_DEFM_JMODE) == EXT4_DEFM_JMODE_ORDERED)
            sbi->s_mount_opt |= EXT4_MOUNT_ORDERED_DATA;
      else if ((def_mount_opts & EXT4_DEFM_JMODE) == EXT4_DEFM_JMODE_WBACK)
            sbi->s_mount_opt |= EXT4_MOUNT_WRITEBACK_DATA;

      if (le16_to_cpu(sbi->s_es->s_errors) == EXT4_ERRORS_PANIC)
            set_opt(sbi->s_mount_opt, ERRORS_PANIC);
      else if (le16_to_cpu(sbi->s_es->s_errors) == EXT4_ERRORS_CONTINUE)
            set_opt(sbi->s_mount_opt, ERRORS_CONT);
      else
            set_opt(sbi->s_mount_opt, ERRORS_RO);

      sbi->s_resuid = le16_to_cpu(es->s_def_resuid);
      sbi->s_resgid = le16_to_cpu(es->s_def_resgid);
      sbi->s_commit_interval = JBD2_DEFAULT_MAX_COMMIT_AGE * HZ;
      sbi->s_min_batch_time = EXT4_DEF_MIN_BATCH_TIME;
      sbi->s_max_batch_time = EXT4_DEF_MAX_BATCH_TIME;
      sbi->s_mb_history_max = default_mb_history_length;

      set_opt(sbi->s_mount_opt, BARRIER);

      /*
       * enable delayed allocation by default
       * Use -o nodelalloc to turn it off
       */
      set_opt(sbi->s_mount_opt, DELALLOC);

      if (!parse_options((char *) data, sb, &journal_devnum,
                     &journal_ioprio, NULL, 0))
            goto failed_mount;

      sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
            ((sbi->s_mount_opt & EXT4_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0);

      if (le32_to_cpu(es->s_rev_level) == EXT4_GOOD_OLD_REV &&
          (EXT4_HAS_COMPAT_FEATURE(sb, ~0U) ||
           EXT4_HAS_RO_COMPAT_FEATURE(sb, ~0U) ||
           EXT4_HAS_INCOMPAT_FEATURE(sb, ~0U)))
            ext4_msg(sb, KERN_WARNING,
                   "feature flags set on rev 0 fs, "
                   "running e2fsck is recommended");

      /*
       * Check feature flags regardless of the revision level, since we
       * previously didn't change the revision level when setting the flags,
       * so there is a chance incompat flags are set on a rev 0 filesystem.
       */
      features = EXT4_HAS_INCOMPAT_FEATURE(sb, ~EXT4_FEATURE_INCOMPAT_SUPP);
      if (features) {
            ext4_msg(sb, KERN_ERR,
                  "Couldn't mount because of "
                  "unsupported optional features (%x)",
                  (le32_to_cpu(EXT4_SB(sb)->s_es->s_feature_incompat) &
                  ~EXT4_FEATURE_INCOMPAT_SUPP));
            goto failed_mount;
      }
      features = EXT4_HAS_RO_COMPAT_FEATURE(sb, ~EXT4_FEATURE_RO_COMPAT_SUPP);
      if (!(sb->s_flags & MS_RDONLY) && features) {
            ext4_msg(sb, KERN_ERR,
                  "Couldn't mount RDWR because of "
                  "unsupported optional features (%x)",
                  (le32_to_cpu(EXT4_SB(sb)->s_es->s_feature_ro_compat) &
                  ~EXT4_FEATURE_RO_COMPAT_SUPP));
            goto failed_mount;
      }
      has_huge_files = EXT4_HAS_RO_COMPAT_FEATURE(sb,
                            EXT4_FEATURE_RO_COMPAT_HUGE_FILE);
      if (has_huge_files) {
            /*
             * Large file size enabled file system can only be
             * mount if kernel is build with CONFIG_LBDAF
             */
            if (sizeof(root->i_blocks) < sizeof(u64) &&
                        !(sb->s_flags & MS_RDONLY)) {
                  ext4_msg(sb, KERN_ERR, "Filesystem with huge "
                              "files cannot be mounted read-write "
                              "without CONFIG_LBDAF");
                  goto failed_mount;
            }
      }
      blocksize = BLOCK_SIZE << le32_to_cpu(es->s_log_block_size);

      if (blocksize < EXT4_MIN_BLOCK_SIZE ||
          blocksize > EXT4_MAX_BLOCK_SIZE) {
            ext4_msg(sb, KERN_ERR,
                   "Unsupported filesystem blocksize %d", blocksize);
            goto failed_mount;
      }

      if (sb->s_blocksize != blocksize) {
            /* Validate the filesystem blocksize */
            if (!sb_set_blocksize(sb, blocksize)) {
                  ext4_msg(sb, KERN_ERR, "bad block size %d",
                              blocksize);
                  goto failed_mount;
            }

            brelse(bh);
            logical_sb_block = sb_block * EXT4_MIN_BLOCK_SIZE;
            offset = do_div(logical_sb_block, blocksize);
            bh = sb_bread(sb, logical_sb_block);
            if (!bh) {
                  ext4_msg(sb, KERN_ERR,
                         "Can't read superblock on 2nd try");
                  goto failed_mount;
            }
            es = (struct ext4_super_block *)(((char *)bh->b_data) + offset);
            sbi->s_es = es;
            if (es->s_magic != cpu_to_le16(EXT4_SUPER_MAGIC)) {
                  ext4_msg(sb, KERN_ERR,
                         "Magic mismatch, very weird!");
                  goto failed_mount;
            }
      }

      sbi->s_bitmap_maxbytes = ext4_max_bitmap_size(sb->s_blocksize_bits,
                                          has_huge_files);
      sb->s_maxbytes = ext4_max_size(sb->s_blocksize_bits, has_huge_files);

      if (le32_to_cpu(es->s_rev_level) == EXT4_GOOD_OLD_REV) {
            sbi->s_inode_size = EXT4_GOOD_OLD_INODE_SIZE;
            sbi->s_first_ino = EXT4_GOOD_OLD_FIRST_INO;
      } else {
            sbi->s_inode_size = le16_to_cpu(es->s_inode_size);
            sbi->s_first_ino = le32_to_cpu(es->s_first_ino);
            if ((sbi->s_inode_size < EXT4_GOOD_OLD_INODE_SIZE) ||
                (!is_power_of_2(sbi->s_inode_size)) ||
                (sbi->s_inode_size > blocksize)) {
                  ext4_msg(sb, KERN_ERR,
                         "unsupported inode size: %d",
                         sbi->s_inode_size);
                  goto failed_mount;
            }
            if (sbi->s_inode_size > EXT4_GOOD_OLD_INODE_SIZE)
                  sb->s_time_gran = 1 << (EXT4_EPOCH_BITS - 2);
      }

      sbi->s_desc_size = le16_to_cpu(es->s_desc_size);
      if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_64BIT)) {
            if (sbi->s_desc_size < EXT4_MIN_DESC_SIZE_64BIT ||
                sbi->s_desc_size > EXT4_MAX_DESC_SIZE ||
                !is_power_of_2(sbi->s_desc_size)) {
                  ext4_msg(sb, KERN_ERR,
                         "unsupported descriptor size %lu",
                         sbi->s_desc_size);
                  goto failed_mount;
            }
      } else
            sbi->s_desc_size = EXT4_MIN_DESC_SIZE;

      sbi->s_blocks_per_group = le32_to_cpu(es->s_blocks_per_group);
      sbi->s_inodes_per_group = le32_to_cpu(es->s_inodes_per_group);
      if (EXT4_INODE_SIZE(sb) == 0 || EXT4_INODES_PER_GROUP(sb) == 0)
            goto cantfind_ext4;

      sbi->s_inodes_per_block = blocksize / EXT4_INODE_SIZE(sb);
      if (sbi->s_inodes_per_block == 0)
            goto cantfind_ext4;
      sbi->s_itb_per_group = sbi->s_inodes_per_group /
                              sbi->s_inodes_per_block;
      sbi->s_desc_per_block = blocksize / EXT4_DESC_SIZE(sb);
      sbi->s_sbh = bh;
      sbi->s_mount_state = le16_to_cpu(es->s_state);
      sbi->s_addr_per_block_bits = ilog2(EXT4_ADDR_PER_BLOCK(sb));
      sbi->s_desc_per_block_bits = ilog2(EXT4_DESC_PER_BLOCK(sb));

      for (i = 0; i < 4; i++)
            sbi->s_hash_seed[i] = le32_to_cpu(es->s_hash_seed[i]);
      sbi->s_def_hash_version = es->s_def_hash_version;
      i = le32_to_cpu(es->s_flags);
      if (i & EXT2_FLAGS_UNSIGNED_HASH)
            sbi->s_hash_unsigned = 3;
      else if ((i & EXT2_FLAGS_SIGNED_HASH) == 0) {
#ifdef __CHAR_UNSIGNED__
            es->s_flags |= cpu_to_le32(EXT2_FLAGS_UNSIGNED_HASH);
            sbi->s_hash_unsigned = 3;
#else
            es->s_flags |= cpu_to_le32(EXT2_FLAGS_SIGNED_HASH);
#endif
            sb->s_dirt = 1;
      }

      if (sbi->s_blocks_per_group > blocksize * 8) {
            ext4_msg(sb, KERN_ERR,
                   "#blocks per group too big: %lu",
                   sbi->s_blocks_per_group);
            goto failed_mount;
      }
      if (sbi->s_inodes_per_group > blocksize * 8) {
            ext4_msg(sb, KERN_ERR,
                   "#inodes per group too big: %lu",
                   sbi->s_inodes_per_group);
            goto failed_mount;
      }

      if (ext4_blocks_count(es) >
                (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) {
            ext4_msg(sb, KERN_ERR, "filesystem"
                  " too large to mount safely");
            if (sizeof(sector_t) < 8)
                  ext4_msg(sb, KERN_WARNING, "CONFIG_LBDAF not enabled");
            goto failed_mount;
      }

      if (EXT4_BLOCKS_PER_GROUP(sb) == 0)
            goto cantfind_ext4;

      /* check blocks count against device size */
      blocks_count = sb->s_bdev->bd_inode->i_size >> sb->s_blocksize_bits;
      if (blocks_count && ext4_blocks_count(es) > blocks_count) {
            ext4_msg(sb, KERN_WARNING, "bad geometry: block count %llu "
                   "exceeds size of device (%llu blocks)",
                   ext4_blocks_count(es), blocks_count);
            goto failed_mount;
      }

      /*
       * It makes no sense for the first data block to be beyond the end
       * of the filesystem.
       */
      if (le32_to_cpu(es->s_first_data_block) >= ext4_blocks_count(es)) {
                ext4_msg(sb, KERN_WARNING, "bad geometry: first data"
                   "block %u is beyond end of filesystem (%llu)",
                   le32_to_cpu(es->s_first_data_block),
                   ext4_blocks_count(es));
            goto failed_mount;
      }
      blocks_count = (ext4_blocks_count(es) -
                  le32_to_cpu(es->s_first_data_block) +
                  EXT4_BLOCKS_PER_GROUP(sb) - 1);
      do_div(blocks_count, EXT4_BLOCKS_PER_GROUP(sb));
      if (blocks_count > ((uint64_t)1<<32) - EXT4_DESC_PER_BLOCK(sb)) {
            ext4_msg(sb, KERN_WARNING, "groups count too large: %u "
                   "(block count %llu, first data block %u, "
                   "blocks per group %lu)", sbi->s_groups_count,
                   ext4_blocks_count(es),
                   le32_to_cpu(es->s_first_data_block),
                   EXT4_BLOCKS_PER_GROUP(sb));
            goto failed_mount;
      }
      sbi->s_groups_count = blocks_count;
      db_count = (sbi->s_groups_count + EXT4_DESC_PER_BLOCK(sb) - 1) /
               EXT4_DESC_PER_BLOCK(sb);
      sbi->s_group_desc = kmalloc(db_count * sizeof(struct buffer_head *),
                            GFP_KERNEL);
      if (sbi->s_group_desc == NULL) {
            ext4_msg(sb, KERN_ERR, "not enough memory");
            goto failed_mount;
      }

#ifdef CONFIG_PROC_FS
      if (ext4_proc_root)
            sbi->s_proc = proc_mkdir(sb->s_id, ext4_proc_root);
#endif

      bgl_lock_init(sbi->s_blockgroup_lock);

      for (i = 0; i < db_count; i++) {
            block = descriptor_loc(sb, logical_sb_block, i);
            sbi->s_group_desc[i] = sb_bread(sb, block);
            if (!sbi->s_group_desc[i]) {
                  ext4_msg(sb, KERN_ERR,
                         "can't read group descriptor %d", i);
                  db_count = i;
                  goto failed_mount2;
            }
      }
      if (!ext4_check_descriptors(sb)) {
            ext4_msg(sb, KERN_ERR, "group descriptors corrupted!");
            goto failed_mount2;
      }
      if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG))
            if (!ext4_fill_flex_info(sb)) {
                  ext4_msg(sb, KERN_ERR,
                         "unable to initialize "
                         "flex_bg meta info!");
                  goto failed_mount2;
            }

      sbi->s_gdb_count = db_count;
      get_random_bytes(&sbi->s_next_generation, sizeof(u32));
      spin_lock_init(&sbi->s_next_gen_lock);

      err = percpu_counter_init(&sbi->s_freeblocks_counter,
                  ext4_count_free_blocks(sb));
      if (!err) {
            err = percpu_counter_init(&sbi->s_freeinodes_counter,
                        ext4_count_free_inodes(sb));
      }
      if (!err) {
            err = percpu_counter_init(&sbi->s_dirs_counter,
                        ext4_count_dirs(sb));
      }
      if (!err) {
            err = percpu_counter_init(&sbi->s_dirtyblocks_counter, 0);
      }
      if (err) {
            ext4_msg(sb, KERN_ERR, "insufficient memory");
            goto failed_mount3;
      }

      sbi->s_stripe = ext4_get_stripe_size(sbi);

      /*
       * set up enough so that it can read an inode
       */
      if (!test_opt(sb, NOLOAD) &&
          EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_HAS_JOURNAL))
            sb->s_op = &ext4_sops;
      else
            sb->s_op = &ext4_nojournal_sops;
      sb->s_export_op = &ext4_export_ops;
      sb->s_xattr = ext4_xattr_handlers;
#ifdef CONFIG_QUOTA
      sb->s_qcop = &ext4_qctl_operations;
      sb->dq_op = &ext4_quota_operations;
#endif
      INIT_LIST_HEAD(&sbi->s_orphan); /* unlinked but open files */
      mutex_init(&sbi->s_orphan_lock);
      mutex_init(&sbi->s_resize_lock);

      sb->s_root = NULL;

      needs_recovery = (es->s_last_orphan != 0 ||
                    EXT4_HAS_INCOMPAT_FEATURE(sb,
                            EXT4_FEATURE_INCOMPAT_RECOVER));

      /*
       * The first inode we look at is the journal inode.  Don't try
       * root first: it may be modified in the journal!
       */
      if (!test_opt(sb, NOLOAD) &&
          EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_HAS_JOURNAL)) {
            if (ext4_load_journal(sb, es, journal_devnum))
                  goto failed_mount3;
            if (!(sb->s_flags & MS_RDONLY) &&
                EXT4_SB(sb)->s_journal->j_failed_commit) {
                  ext4_msg(sb, KERN_CRIT, "error: "
                         "ext4_fill_super: Journal transaction "
                         "%u is corrupt",
                         EXT4_SB(sb)->s_journal->j_failed_commit);
                  if (test_opt(sb, ERRORS_RO)) {
                        ext4_msg(sb, KERN_CRIT,
                               "Mounting filesystem read-only");
                        sb->s_flags |= MS_RDONLY;
                        EXT4_SB(sb)->s_mount_state |= EXT4_ERROR_FS;
                        es->s_state |= cpu_to_le16(EXT4_ERROR_FS);
                  }
                  if (test_opt(sb, ERRORS_PANIC)) {
                        EXT4_SB(sb)->s_mount_state |= EXT4_ERROR_FS;
                        es->s_state |= cpu_to_le16(EXT4_ERROR_FS);
                        ext4_commit_super(sb, 1);
                        goto failed_mount4;
                  }
            }
      } else if (test_opt(sb, NOLOAD) && !(sb->s_flags & MS_RDONLY) &&
            EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER)) {
            ext4_msg(sb, KERN_ERR, "required journal recovery "
                   "suppressed and not mounted read-only");
            goto failed_mount4;
      } else {
            clear_opt(sbi->s_mount_opt, DATA_FLAGS);
            set_opt(sbi->s_mount_opt, WRITEBACK_DATA);
            sbi->s_journal = NULL;
            needs_recovery = 0;
            goto no_journal;
      }

      if (ext4_blocks_count(es) > 0xffffffffULL &&
          !jbd2_journal_set_features(EXT4_SB(sb)->s_journal, 0, 0,
                               JBD2_FEATURE_INCOMPAT_64BIT)) {
            ext4_msg(sb, KERN_ERR, "Failed to set 64-bit journal feature");
            goto failed_mount4;
      }

      if (test_opt(sb, JOURNAL_ASYNC_COMMIT)) {
            jbd2_journal_set_features(sbi->s_journal,
                        JBD2_FEATURE_COMPAT_CHECKSUM, 0,
                        JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT);
      } else if (test_opt(sb, JOURNAL_CHECKSUM)) {
            jbd2_journal_set_features(sbi->s_journal,
                        JBD2_FEATURE_COMPAT_CHECKSUM, 0, 0);
            jbd2_journal_clear_features(sbi->s_journal, 0, 0,
                        JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT);
      } else {
            jbd2_journal_clear_features(sbi->s_journal,
                        JBD2_FEATURE_COMPAT_CHECKSUM, 0,
                        JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT);
      }

      /* We have now updated the journal if required, so we can
       * validate the data journaling mode. */
      switch (test_opt(sb, DATA_FLAGS)) {
      case 0:
            /* No mode set, assume a default based on the journal
             * capabilities: ORDERED_DATA if the journal can
             * cope, else JOURNAL_DATA
             */
            if (jbd2_journal_check_available_features
                (sbi->s_journal, 0, 0, JBD2_FEATURE_INCOMPAT_REVOKE))
                  set_opt(sbi->s_mount_opt, ORDERED_DATA);
            else
                  set_opt(sbi->s_mount_opt, JOURNAL_DATA);
            break;

      case EXT4_MOUNT_ORDERED_DATA:
      case EXT4_MOUNT_WRITEBACK_DATA:
            if (!jbd2_journal_check_available_features
                (sbi->s_journal, 0, 0, JBD2_FEATURE_INCOMPAT_REVOKE)) {
                  ext4_msg(sb, KERN_ERR, "Journal does not support "
                         "requested data journaling mode");
                  goto failed_mount4;
            }
      default:
            break;
      }
      set_task_ioprio(sbi->s_journal->j_task, journal_ioprio);

no_journal:

      if (test_opt(sb, NOBH)) {
            if (!(test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_WRITEBACK_DATA)) {
                  ext4_msg(sb, KERN_WARNING, "Ignoring nobh option - "
                        "its supported only with writeback mode");
                  clear_opt(sbi->s_mount_opt, NOBH);
            }
      }
      /*
       * The jbd2_journal_load will have done any necessary log recovery,
       * so we can safely mount the rest of the filesystem now.
       */

      root = ext4_iget(sb, EXT4_ROOT_INO);
      if (IS_ERR(root)) {
            ext4_msg(sb, KERN_ERR, "get root inode failed");
            ret = PTR_ERR(root);
            goto failed_mount4;
      }
      if (!S_ISDIR(root->i_mode) || !root->i_blocks || !root->i_size) {
            iput(root);
            ext4_msg(sb, KERN_ERR, "corrupt root inode, run e2fsck");
            goto failed_mount4;
      }
      sb->s_root = d_alloc_root(root);
      if (!sb->s_root) {
            ext4_msg(sb, KERN_ERR, "get root dentry failed");
            iput(root);
            ret = -ENOMEM;
            goto failed_mount4;
      }

      ext4_setup_super(sb, es, sb->s_flags & MS_RDONLY);

      /* determine the minimum size of new large inodes, if present */
      if (sbi->s_inode_size > EXT4_GOOD_OLD_INODE_SIZE) {
            sbi->s_want_extra_isize = sizeof(struct ext4_inode) -
                                         EXT4_GOOD_OLD_INODE_SIZE;
            if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
                               EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE)) {
                  if (sbi->s_want_extra_isize <
                      le16_to_cpu(es->s_want_extra_isize))
                        sbi->s_want_extra_isize =
                              le16_to_cpu(es->s_want_extra_isize);
                  if (sbi->s_want_extra_isize <
                      le16_to_cpu(es->s_min_extra_isize))
                        sbi->s_want_extra_isize =
                              le16_to_cpu(es->s_min_extra_isize);
            }
      }
      /* Check if enough inode space is available */
      if (EXT4_GOOD_OLD_INODE_SIZE + sbi->s_want_extra_isize >
                                          sbi->s_inode_size) {
            sbi->s_want_extra_isize = sizeof(struct ext4_inode) -
                                           EXT4_GOOD_OLD_INODE_SIZE;
            ext4_msg(sb, KERN_INFO, "required extra inode space not"
                   "available");
      }

      if (test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA) {
            ext4_msg(sb, KERN_WARNING, "Ignoring delalloc option - "
                   "requested data journaling mode");
            clear_opt(sbi->s_mount_opt, DELALLOC);
      } else if (test_opt(sb, DELALLOC))
            ext4_msg(sb, KERN_INFO, "delayed allocation enabled");

      err = ext4_setup_system_zone(sb);
      if (err) {
            ext4_msg(sb, KERN_ERR, "failed to initialize system "
                   "zone (%d)\n", err);
            goto failed_mount4;
      }

      ext4_ext_init(sb);
      err = ext4_mb_init(sb, needs_recovery);
      if (err) {
            ext4_msg(sb, KERN_ERR, "failed to initalize mballoc (%d)",
                   err);
            goto failed_mount4;
      }

      sbi->s_kobj.kset = ext4_kset;
      init_completion(&sbi->s_kobj_unregister);
      err = kobject_init_and_add(&sbi->s_kobj, &ext4_ktype, NULL,
                           "%s", sb->s_id);
      if (err) {
            ext4_mb_release(sb);
            ext4_ext_release(sb);
            goto failed_mount4;
      };

      EXT4_SB(sb)->s_mount_state |= EXT4_ORPHAN_FS;
      ext4_orphan_cleanup(sb, es);
      EXT4_SB(sb)->s_mount_state &= ~EXT4_ORPHAN_FS;
      if (needs_recovery) {
            ext4_msg(sb, KERN_INFO, "recovery complete");
            ext4_mark_recovery_complete(sb, es);
      }
      if (EXT4_SB(sb)->s_journal) {
            if (test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA)
                  descr = " journalled data mode";
            else if (test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_ORDERED_DATA)
                  descr = " ordered data mode";
            else
                  descr = " writeback data mode";
      } else
            descr = "out journal";

      ext4_msg(sb, KERN_INFO, "mounted filesystem with%s", descr);

      lock_kernel();
      return 0;

cantfind_ext4:
      if (!silent)
            ext4_msg(sb, KERN_ERR, "VFS: Can't find ext4 filesystem");
      goto failed_mount;

failed_mount4:
      ext4_msg(sb, KERN_ERR, "mount failed");
      ext4_release_system_zone(sb);
      if (sbi->s_journal) {
            jbd2_journal_destroy(sbi->s_journal);
            sbi->s_journal = NULL;
      }
failed_mount3:
      if (sbi->s_flex_groups) {
            if (is_vmalloc_addr(sbi->s_flex_groups))
                  vfree(sbi->s_flex_groups);
            else
                  kfree(sbi->s_flex_groups);
      }
      percpu_counter_destroy(&sbi->s_freeblocks_counter);
      percpu_counter_destroy(&sbi->s_freeinodes_counter);
      percpu_counter_destroy(&sbi->s_dirs_counter);
      percpu_counter_destroy(&sbi->s_dirtyblocks_counter);
failed_mount2:
      for (i = 0; i < db_count; i++)
            brelse(sbi->s_group_desc[i]);
      kfree(sbi->s_group_desc);
failed_mount:
      if (sbi->s_proc) {
            remove_proc_entry(sb->s_id, ext4_proc_root);
      }
#ifdef CONFIG_QUOTA
      for (i = 0; i < MAXQUOTAS; i++)
            kfree(sbi->s_qf_names[i]);
#endif
      ext4_blkdev_remove(sbi);
      brelse(bh);
out_fail:
      sb->s_fs_info = NULL;
      kfree(sbi->s_blockgroup_lock);
      kfree(sbi);
      lock_kernel();
      return ret;
}

/*
 * Setup any per-fs journal parameters now.  We'll do this both on
 * initial mount, once the journal has been initialised but before we've
 * done any recovery; and again on any subsequent remount.
 */
static void ext4_init_journal_params(struct super_block *sb, journal_t *journal)
{
      struct ext4_sb_info *sbi = EXT4_SB(sb);

      journal->j_commit_interval = sbi->s_commit_interval;
      journal->j_min_batch_time = sbi->s_min_batch_time;
      journal->j_max_batch_time = sbi->s_max_batch_time;

      spin_lock(&journal->j_state_lock);
      if (test_opt(sb, BARRIER))
            journal->j_flags |= JBD2_BARRIER;
      else
            journal->j_flags &= ~JBD2_BARRIER;
      if (test_opt(sb, DATA_ERR_ABORT))
            journal->j_flags |= JBD2_ABORT_ON_SYNCDATA_ERR;
      else
            journal->j_flags &= ~JBD2_ABORT_ON_SYNCDATA_ERR;
      spin_unlock(&journal->j_state_lock);
}

static journal_t *ext4_get_journal(struct super_block *sb,
                           unsigned int journal_inum)
{
      struct inode *journal_inode;
      journal_t *journal;

      BUG_ON(!EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_HAS_JOURNAL));

      /* First, test for the existence of a valid inode on disk.  Bad
       * things happen if we iget() an unused inode, as the subsequent
       * iput() will try to delete it. */

      journal_inode = ext4_iget(sb, journal_inum);
      if (IS_ERR(journal_inode)) {
            ext4_msg(sb, KERN_ERR, "no journal found");
            return NULL;
      }
      if (!journal_inode->i_nlink) {
            make_bad_inode(journal_inode);
            iput(journal_inode);
            ext4_msg(sb, KERN_ERR, "journal inode is deleted");
            return NULL;
      }

      jbd_debug(2, "Journal inode found at %p: %lld bytes\n",
              journal_inode, journal_inode->i_size);
      if (!S_ISREG(journal_inode->i_mode)) {
            ext4_msg(sb, KERN_ERR, "invalid journal inode");
            iput(journal_inode);
            return NULL;
      }

      journal = jbd2_journal_init_inode(journal_inode);
      if (!journal) {
            ext4_msg(sb, KERN_ERR, "Could not load journal inode");
            iput(journal_inode);
            return NULL;
      }
      journal->j_private = sb;
      ext4_init_journal_params(sb, journal);
      return journal;
}

static journal_t *ext4_get_dev_journal(struct super_block *sb,
                               dev_t j_dev)
{
      struct buffer_head *bh;
      journal_t *journal;
      ext4_fsblk_t start;
      ext4_fsblk_t len;
      int hblock, blocksize;
      ext4_fsblk_t sb_block;
      unsigned long offset;
      struct ext4_super_block *es;
      struct block_device *bdev;

      BUG_ON(!EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_HAS_JOURNAL));

      bdev = ext4_blkdev_get(j_dev, sb);
      if (bdev == NULL)
            return NULL;

      if (bd_claim(bdev, sb)) {
            ext4_msg(sb, KERN_ERR,
                  "failed to claim external journal device");
            blkdev_put(bdev, FMODE_READ|FMODE_WRITE);
            return NULL;
      }

      blocksize = sb->s_blocksize;
      hblock = bdev_logical_block_size(bdev);
      if (blocksize < hblock) {
            ext4_msg(sb, KERN_ERR,
                  "blocksize too small for journal device");
            goto out_bdev;
      }

      sb_block = EXT4_MIN_BLOCK_SIZE / blocksize;
      offset = EXT4_MIN_BLOCK_SIZE % blocksize;
      set_blocksize(bdev, blocksize);
      if (!(bh = __bread(bdev, sb_block, blocksize))) {
            ext4_msg(sb, KERN_ERR, "couldn't read superblock of "
                   "external journal");
            goto out_bdev;
      }

      es = (struct ext4_super_block *) (((char *)bh->b_data) + offset);
      if ((le16_to_cpu(es->s_magic) != EXT4_SUPER_MAGIC) ||
          !(le32_to_cpu(es->s_feature_incompat) &
            EXT4_FEATURE_INCOMPAT_JOURNAL_DEV)) {
            ext4_msg(sb, KERN_ERR, "external journal has "
                              "bad superblock");
            brelse(bh);
            goto out_bdev;
      }

      if (memcmp(EXT4_SB(sb)->s_es->s_journal_uuid, es->s_uuid, 16)) {
            ext4_msg(sb, KERN_ERR, "journal UUID does not match");
            brelse(bh);
            goto out_bdev;
      }

      len = ext4_blocks_count(es);
      start = sb_block + 1;
      brelse(bh); /* we're done with the superblock */

      journal = jbd2_journal_init_dev(bdev, sb->s_bdev,
                              start, len, blocksize);
      if (!journal) {
            ext4_msg(sb, KERN_ERR, "failed to create device journal");
            goto out_bdev;
      }
      journal->j_private = sb;
      ll_rw_block(READ, 1, &journal->j_sb_buffer);
      wait_on_buffer(journal->j_sb_buffer);
      if (!buffer_uptodate(journal->j_sb_buffer)) {
            ext4_msg(sb, KERN_ERR, "I/O error on journal device");
            goto out_journal;
      }
      if (be32_to_cpu(journal->j_superblock->s_nr_users) != 1) {
            ext4_msg(sb, KERN_ERR, "External journal has more than one "
                              "user (unsupported) - %d",
                  be32_to_cpu(journal->j_superblock->s_nr_users));
            goto out_journal;
      }
      EXT4_SB(sb)->journal_bdev = bdev;
      ext4_init_journal_params(sb, journal);
      return journal;

out_journal:
      jbd2_journal_destroy(journal);
out_bdev:
      ext4_blkdev_put(bdev);
      return NULL;
}

static int ext4_load_journal(struct super_block *sb,
                       struct ext4_super_block *es,
                       unsigned long journal_devnum)
{
      journal_t *journal;
      unsigned int journal_inum = le32_to_cpu(es->s_journal_inum);
      dev_t journal_dev;
      int err = 0;
      int really_read_only;

      BUG_ON(!EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_HAS_JOURNAL));

      if (journal_devnum &&
          journal_devnum != le32_to_cpu(es->s_journal_dev)) {
            ext4_msg(sb, KERN_INFO, "external journal device major/minor "
                  "numbers have changed");
            journal_dev = new_decode_dev(journal_devnum);
      } else
            journal_dev = new_decode_dev(le32_to_cpu(es->s_journal_dev));

      really_read_only = bdev_read_only(sb->s_bdev);

      /*
       * Are we loading a blank journal or performing recovery after a
       * crash?  For recovery, we need to check in advance whether we
       * can get read-write access to the device.
       */
      if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER)) {
            if (sb->s_flags & MS_RDONLY) {
                  ext4_msg(sb, KERN_INFO, "INFO: recovery "
                              "required on readonly filesystem");
                  if (really_read_only) {
                        ext4_msg(sb, KERN_ERR, "write access "
                              "unavailable, cannot proceed");
                        return -EROFS;
                  }
                  ext4_msg(sb, KERN_INFO, "write access will "
                         "be enabled during recovery");
            }
      }

      if (journal_inum && journal_dev) {
            ext4_msg(sb, KERN_ERR, "filesystem has both journal "
                   "and inode journals!");
            return -EINVAL;
      }

      if (journal_inum) {
            if (!(journal = ext4_get_journal(sb, journal_inum)))
                  return -EINVAL;
      } else {
            if (!(journal = ext4_get_dev_journal(sb, journal_dev)))
                  return -EINVAL;
      }

      if (journal->j_flags & JBD2_BARRIER)
            ext4_msg(sb, KERN_INFO, "barriers enabled");
      else
            ext4_msg(sb, KERN_INFO, "barriers disabled");

      if (!really_read_only && test_opt(sb, UPDATE_JOURNAL)) {
            err = jbd2_journal_update_format(journal);
            if (err)  {
                  ext4_msg(sb, KERN_ERR, "error updating journal");
                  jbd2_journal_destroy(journal);
                  return err;
            }
      }

      if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER))
            err = jbd2_journal_wipe(journal, !really_read_only);
      if (!err)
            err = jbd2_journal_load(journal);

      if (err) {
            ext4_msg(sb, KERN_ERR, "error loading journal");
            jbd2_journal_destroy(journal);
            return err;
      }

      EXT4_SB(sb)->s_journal = journal;
      ext4_clear_journal_err(sb, es);

      if (journal_devnum &&
          journal_devnum != le32_to_cpu(es->s_journal_dev)) {
            es->s_journal_dev = cpu_to_le32(journal_devnum);

            /* Make sure we flush the recovery flag to disk. */
            ext4_commit_super(sb, 1);
      }

      return 0;
}

static int ext4_commit_super(struct super_block *sb, int sync)
{
      struct ext4_super_block *es = EXT4_SB(sb)->s_es;
      struct buffer_head *sbh = EXT4_SB(sb)->s_sbh;
      int error = 0;

      if (!sbh)
            return error;
      if (buffer_write_io_error(sbh)) {
            /*
             * Oh, dear.  A previous attempt to write the
             * superblock failed.  This could happen because the
             * USB device was yanked out.  Or it could happen to
             * be a transient write error and maybe the block will
             * be remapped.  Nothing we can do but to retry the
             * write and hope for the best.
             */
            ext4_msg(sb, KERN_ERR, "previous I/O error to "
                   "superblock detected");
            clear_buffer_write_io_error(sbh);
            set_buffer_uptodate(sbh);
      }
      es->s_wtime = cpu_to_le32(get_seconds());
      es->s_kbytes_written =
            cpu_to_le64(EXT4_SB(sb)->s_kbytes_written + 
                      ((part_stat_read(sb->s_bdev->bd_part, sectors[1]) -
                        EXT4_SB(sb)->s_sectors_written_start) >> 1));
      ext4_free_blocks_count_set(es, percpu_counter_sum_positive(
                              &EXT4_SB(sb)->s_freeblocks_counter));
      es->s_free_inodes_count = cpu_to_le32(percpu_counter_sum_positive(
                              &EXT4_SB(sb)->s_freeinodes_counter));
      sb->s_dirt = 0;
      BUFFER_TRACE(sbh, "marking dirty");
      mark_buffer_dirty(sbh);
      if (sync) {
            error = sync_dirty_buffer(sbh);
            if (error)
                  return error;

            error = buffer_write_io_error(sbh);
            if (error) {
                  ext4_msg(sb, KERN_ERR, "I/O error while writing "
                         "superblock");
                  clear_buffer_write_io_error(sbh);
                  set_buffer_uptodate(sbh);
            }
      }
      return error;
}

/*
 * Have we just finished recovery?  If so, and if we are mounting (or
 * remounting) the filesystem readonly, then we will end up with a
 * consistent fs on disk.  Record that fact.
 */
static void ext4_mark_recovery_complete(struct super_block *sb,
                              struct ext4_super_block *es)
{
      journal_t *journal = EXT4_SB(sb)->s_journal;

      if (!EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_HAS_JOURNAL)) {
            BUG_ON(journal != NULL);
            return;
      }
      jbd2_journal_lock_updates(journal);
      if (jbd2_journal_flush(journal) < 0)
            goto out;

      if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER) &&
          sb->s_flags & MS_RDONLY) {
            EXT4_CLEAR_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER);
            ext4_commit_super(sb, 1);
      }

out:
      jbd2_journal_unlock_updates(journal);
}

/*
 * If we are mounting (or read-write remounting) a filesystem whose journal
 * has recorded an error from a previous lifetime, move that error to the
 * main filesystem now.
 */
static void ext4_clear_journal_err(struct super_block *sb,
                           struct ext4_super_block *es)
{
      journal_t *journal;
      int j_errno;
      const char *errstr;

      BUG_ON(!EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_HAS_JOURNAL));

      journal = EXT4_SB(sb)->s_journal;

      /*
       * Now check for any error status which may have been recorded in the
       * journal by a prior ext4_error() or ext4_abort()
       */

      j_errno = jbd2_journal_errno(journal);
      if (j_errno) {
            char nbuf[16];

            errstr = ext4_decode_error(sb, j_errno, nbuf);
            ext4_warning(sb, __func__, "Filesystem error recorded "
                       "from previous mount: %s", errstr);
            ext4_warning(sb, __func__, "Marking fs in need of "
                       "filesystem check.");

            EXT4_SB(sb)->s_mount_state |= EXT4_ERROR_FS;
            es->s_state |= cpu_to_le16(EXT4_ERROR_FS);
            ext4_commit_super(sb, 1);

            jbd2_journal_clear_err(journal);
      }
}

/*
 * Force the running and committing transactions to commit,
 * and wait on the commit.
 */
int ext4_force_commit(struct super_block *sb)
{
      journal_t *journal;
      int ret = 0;

      if (sb->s_flags & MS_RDONLY)
            return 0;

      journal = EXT4_SB(sb)->s_journal;
      if (journal)
            ret = ext4_journal_force_commit(journal);

      return ret;
}

static void ext4_write_super(struct super_block *sb)
{
      lock_super(sb);
      ext4_commit_super(sb, 1);
      unlock_super(sb);
}

static int ext4_sync_fs(struct super_block *sb, int wait)
{
      int ret = 0;
      tid_t target;

      trace_ext4_sync_fs(sb, wait);
      if (jbd2_journal_start_commit(EXT4_SB(sb)->s_journal, &target)) {
            if (wait)
                  jbd2_log_wait_commit(EXT4_SB(sb)->s_journal, target);
      }
      return ret;
}

/*
 * LVM calls this function before a (read-only) snapshot is created.  This
 * gives us a chance to flush the journal completely and mark the fs clean.
 */
static int ext4_freeze(struct super_block *sb)
{
      int error = 0;
      journal_t *journal;

      if (sb->s_flags & MS_RDONLY)
            return 0;

      journal = EXT4_SB(sb)->s_journal;

      /* Now we set up the journal barrier. */
      jbd2_journal_lock_updates(journal);

      /*
       * Don't clear the needs_recovery flag if we failed to flush
       * the journal.
       */
      error = jbd2_journal_flush(journal);
      if (error < 0) {
      out:
            jbd2_journal_unlock_updates(journal);
            return error;
      }

      /* Journal blocked and flushed, clear needs_recovery flag. */
      EXT4_CLEAR_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER);
      error = ext4_commit_super(sb, 1);
      if (error)
            goto out;
      return 0;
}

/*
 * Called by LVM after the snapshot is done.  We need to reset the RECOVER
 * flag here, even though the filesystem is not technically dirty yet.
 */
static int ext4_unfreeze(struct super_block *sb)
{
      if (sb->s_flags & MS_RDONLY)
            return 0;

      lock_super(sb);
      /* Reset the needs_recovery flag before the fs is unlocked. */
      EXT4_SET_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER);
      ext4_commit_super(sb, 1);
      unlock_super(sb);
      jbd2_journal_unlock_updates(EXT4_SB(sb)->s_journal);
      return 0;
}

static int ext4_remount(struct super_block *sb, int *flags, char *data)
{
      struct ext4_super_block *es;
      struct ext4_sb_info *sbi = EXT4_SB(sb);
      ext4_fsblk_t n_blocks_count = 0;
      unsigned long old_sb_flags;
      struct ext4_mount_options old_opts;
      ext4_group_t g;
      unsigned int journal_ioprio = DEFAULT_JOURNAL_IOPRIO;
      int err;
#ifdef CONFIG_QUOTA
      int i;
#endif

      lock_kernel();

      /* Store the original options */
      lock_super(sb);
      old_sb_flags = sb->s_flags;
      old_opts.s_mount_opt = sbi->s_mount_opt;
      old_opts.s_resuid = sbi->s_resuid;
      old_opts.s_resgid = sbi->s_resgid;
      old_opts.s_commit_interval = sbi->s_commit_interval;
      old_opts.s_min_batch_time = sbi->s_min_batch_time;
      old_opts.s_max_batch_time = sbi->s_max_batch_time;
#ifdef CONFIG_QUOTA
      old_opts.s_jquota_fmt = sbi->s_jquota_fmt;
      for (i = 0; i < MAXQUOTAS; i++)
            old_opts.s_qf_names[i] = sbi->s_qf_names[i];
#endif
      if (sbi->s_journal && sbi->s_journal->j_task->io_context)
            journal_ioprio = sbi->s_journal->j_task->io_context->ioprio;

      /*
       * Allow the "check" option to be passed as a remount option.
       */
      if (!parse_options(data, sb, NULL, &journal_ioprio,
                     &n_blocks_count, 1)) {
            err = -EINVAL;
            goto restore_opts;
      }

      if (sbi->s_mount_flags & EXT4_MF_FS_ABORTED)
            ext4_abort(sb, __func__, "Abort forced by user");

      sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
            ((sbi->s_mount_opt & EXT4_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0);

      es = sbi->s_es;

      if (sbi->s_journal) {
            ext4_init_journal_params(sb, sbi->s_journal);
            set_task_ioprio(sbi->s_journal->j_task, journal_ioprio);
      }

      if ((*flags & MS_RDONLY) != (sb->s_flags & MS_RDONLY) ||
            n_blocks_count > ext4_blocks_count(es)) {
            if (sbi->s_mount_flags & EXT4_MF_FS_ABORTED) {
                  err = -EROFS;
                  goto restore_opts;
            }

            if (*flags & MS_RDONLY) {
                  /*
                   * First of all, the unconditional stuff we have to do
                   * to disable replay of the journal when we next remount
                   */
                  sb->s_flags |= MS_RDONLY;

                  /*
                   * OK, test if we are remounting a valid rw partition
                   * readonly, and if so set the rdonly flag and then
                   * mark the partition as valid again.
                   */
                  if (!(es->s_state & cpu_to_le16(EXT4_VALID_FS)) &&
                      (sbi->s_mount_state & EXT4_VALID_FS))
                        es->s_state = cpu_to_le16(sbi->s_mount_state);

                  if (sbi->s_journal)
                        ext4_mark_recovery_complete(sb, es);
            } else {
                  int ret;
                  if ((ret = EXT4_HAS_RO_COMPAT_FEATURE(sb,
                              ~EXT4_FEATURE_RO_COMPAT_SUPP))) {
                        ext4_msg(sb, KERN_WARNING, "couldn't "
                               "remount RDWR because of unsupported "
                               "optional features (%x)",
                        (le32_to_cpu(sbi->s_es->s_feature_ro_compat) &
                              ~EXT4_FEATURE_RO_COMPAT_SUPP));
                        err = -EROFS;
                        goto restore_opts;
                  }

                  /*
                   * Make sure the group descriptor checksums
                   * are sane.  If they aren't, refuse to remount r/w.
                   */
                  for (g = 0; g < sbi->s_groups_count; g++) {
                        struct ext4_group_desc *gdp =
                              ext4_get_group_desc(sb, g, NULL);

                        if (!ext4_group_desc_csum_verify(sbi, g, gdp)) {
                              ext4_msg(sb, KERN_ERR,
             "ext4_remount: Checksum for group %u failed (%u!=%u)",
            g, le16_to_cpu(ext4_group_desc_csum(sbi, g, gdp)),
                                     le16_to_cpu(gdp->bg_checksum));
                              err = -EINVAL;
                              goto restore_opts;
                        }
                  }

                  /*
                   * If we have an unprocessed orphan list hanging
                   * around from a previously readonly bdev mount,
                   * require a full umount/remount for now.
                   */
                  if (es->s_last_orphan) {
                        ext4_msg(sb, KERN_WARNING, "Couldn't "
                               "remount RDWR because of unprocessed "
                               "orphan inode list.  Please "
                               "umount/remount instead");
                        err = -EINVAL;
                        goto restore_opts;
                  }

                  /*
                   * Mounting a RDONLY partition read-write, so reread
                   * and store the current valid flag.  (It may have
                   * been changed by e2fsck since we originally mounted
                   * the partition.)
                   */
                  if (sbi->s_journal)
                        ext4_clear_journal_err(sb, es);
                  sbi->s_mount_state = le16_to_cpu(es->s_state);
                  if ((err = ext4_group_extend(sb, es, n_blocks_count)))
                        goto restore_opts;
                  if (!ext4_setup_super(sb, es, 0))
                        sb->s_flags &= ~MS_RDONLY;
            }
      }
      ext4_setup_system_zone(sb);
      if (sbi->s_journal == NULL)
            ext4_commit_super(sb, 1);

#ifdef CONFIG_QUOTA
      /* Release old quota file names */
      for (i = 0; i < MAXQUOTAS; i++)
            if (old_opts.s_qf_names[i] &&
                old_opts.s_qf_names[i] != sbi->s_qf_names[i])
                  kfree(old_opts.s_qf_names[i]);
#endif
      unlock_super(sb);
      unlock_kernel();
      return 0;

restore_opts:
      sb->s_flags = old_sb_flags;
      sbi->s_mount_opt = old_opts.s_mount_opt;
      sbi->s_resuid = old_opts.s_resuid;
      sbi->s_resgid = old_opts.s_resgid;
      sbi->s_commit_interval = old_opts.s_commit_interval;
      sbi->s_min_batch_time = old_opts.s_min_batch_time;
      sbi->s_max_batch_time = old_opts.s_max_batch_time;
#ifdef CONFIG_QUOTA
      sbi->s_jquota_fmt = old_opts.s_jquota_fmt;
      for (i = 0; i < MAXQUOTAS; i++) {
            if (sbi->s_qf_names[i] &&
                old_opts.s_qf_names[i] != sbi->s_qf_names[i])
                  kfree(sbi->s_qf_names[i]);
            sbi->s_qf_names[i] = old_opts.s_qf_names[i];
      }
#endif
      unlock_super(sb);
      unlock_kernel();
      return err;
}

static int ext4_statfs(struct dentry *dentry, struct kstatfs *buf)
{
      struct super_block *sb = dentry->d_sb;
      struct ext4_sb_info *sbi = EXT4_SB(sb);
      struct ext4_super_block *es = sbi->s_es;
      u64 fsid;

      if (test_opt(sb, MINIX_DF)) {
            sbi->s_overhead_last = 0;
      } else if (sbi->s_blocks_last != ext4_blocks_count(es)) {
            ext4_group_t i, ngroups = ext4_get_groups_count(sb);
            ext4_fsblk_t overhead = 0;

            /*
             * Compute the overhead (FS structures).  This is constant
             * for a given filesystem unless the number of block groups
             * changes so we cache the previous value until it does.
             */

            /*
             * All of the blocks before first_data_block are
             * overhead
             */
            overhead = le32_to_cpu(es->s_first_data_block);

            /*
             * Add the overhead attributed to the superblock and
             * block group descriptors.  If the sparse superblocks
             * feature is turned on, then not all groups have this.
             */
            for (i = 0; i < ngroups; i++) {
                  overhead += ext4_bg_has_super(sb, i) +
                        ext4_bg_num_gdb(sb, i);
                  cond_resched();
            }

            /*
             * Every block group has an inode bitmap, a block
             * bitmap, and an inode table.
             */
            overhead += ngroups * (2 + sbi->s_itb_per_group);
            sbi->s_overhead_last = overhead;
            smp_wmb();
            sbi->s_blocks_last = ext4_blocks_count(es);
      }

      buf->f_type = EXT4_SUPER_MAGIC;
      buf->f_bsize = sb->s_blocksize;
      buf->f_blocks = ext4_blocks_count(es) - sbi->s_overhead_last;
      buf->f_bfree = percpu_counter_sum_positive(&sbi->s_freeblocks_counter) -
                   percpu_counter_sum_positive(&sbi->s_dirtyblocks_counter);
      ext4_free_blocks_count_set(es, buf->f_bfree);
      buf->f_bavail = buf->f_bfree - ext4_r_blocks_count(es);
      if (buf->f_bfree < ext4_r_blocks_count(es))
            buf->f_bavail = 0;
      buf->f_files = le32_to_cpu(es->s_inodes_count);
      buf->f_ffree = percpu_counter_sum_positive(&sbi->s_freeinodes_counter);
      es->s_free_inodes_count = cpu_to_le32(buf->f_ffree);
      buf->f_namelen = EXT4_NAME_LEN;
      fsid = le64_to_cpup((void *)es->s_uuid) ^
             le64_to_cpup((void *)es->s_uuid + sizeof(u64));
      buf->f_fsid.val[0] = fsid & 0xFFFFFFFFUL;
      buf->f_fsid.val[1] = (fsid >> 32) & 0xFFFFFFFFUL;

      return 0;
}

/* Helper function for writing quotas on sync - we need to start transaction
 * before quota file is locked for write. Otherwise the are possible deadlocks:
 * Process 1                         Process 2
 * ext4_create()                     quota_sync()
 *   jbd2_journal_start()                  write_dquot()
 *   vfs_dq_init()                         down(dqio_mutex)
 *     down(dqio_mutex)                    jbd2_journal_start()
 *
 */

#ifdef CONFIG_QUOTA

static inline struct inode *dquot_to_inode(struct dquot *dquot)
{
      return sb_dqopt(dquot->dq_sb)->files[dquot->dq_type];
}

static int ext4_write_dquot(struct dquot *dquot)
{
      int ret, err;
      handle_t *handle;
      struct inode *inode;

      inode = dquot_to_inode(dquot);
      handle = ext4_journal_start(inode,
                            EXT4_QUOTA_TRANS_BLOCKS(dquot->dq_sb));
      if (IS_ERR(handle))
            return PTR_ERR(handle);
      ret = dquot_commit(dquot);
      err = ext4_journal_stop(handle);
      if (!ret)
            ret = err;
      return ret;
}

static int ext4_acquire_dquot(struct dquot *dquot)
{
      int ret, err;
      handle_t *handle;

      handle = ext4_journal_start(dquot_to_inode(dquot),
                            EXT4_QUOTA_INIT_BLOCKS(dquot->dq_sb));
      if (IS_ERR(handle))
            return PTR_ERR(handle);
      ret = dquot_acquire(dquot);
      err = ext4_journal_stop(handle);
      if (!ret)
            ret = err;
      return ret;
}

static int ext4_release_dquot(struct dquot *dquot)
{
      int ret, err;
      handle_t *handle;

      handle = ext4_journal_start(dquot_to_inode(dquot),
                            EXT4_QUOTA_DEL_BLOCKS(dquot->dq_sb));
      if (IS_ERR(handle)) {
            /* Release dquot anyway to avoid endless cycle in dqput() */
            dquot_release(dquot);
            return PTR_ERR(handle);
      }
      ret = dquot_release(dquot);
      err = ext4_journal_stop(handle);
      if (!ret)
            ret = err;
      return ret;
}

static int ext4_mark_dquot_dirty(struct dquot *dquot)
{
      /* Are we journaling quotas? */
      if (EXT4_SB(dquot->dq_sb)->s_qf_names[USRQUOTA] ||
          EXT4_SB(dquot->dq_sb)->s_qf_names[GRPQUOTA]) {
            dquot_mark_dquot_dirty(dquot);
            return ext4_write_dquot(dquot);
      } else {
            return dquot_mark_dquot_dirty(dquot);
      }
}

static int ext4_write_info(struct super_block *sb, int type)
{
      int ret, err;
      handle_t *handle;

      /* Data block + inode block */
      handle = ext4_journal_start(sb->s_root->d_inode, 2);
      if (IS_ERR(handle))
            return PTR_ERR(handle);
      ret = dquot_commit_info(sb, type);
      err = ext4_journal_stop(handle);
      if (!ret)
            ret = err;
      return ret;
}

/*
 * Turn on quotas during mount time - we need to find
 * the quota file and such...
 */
static int ext4_quota_on_mount(struct super_block *sb, int type)
{
      return vfs_quota_on_mount(sb, EXT4_SB(sb)->s_qf_names[type],
                          EXT4_SB(sb)->s_jquota_fmt, type);
}

/*
 * Standard function to be called on quota_on
 */
static int ext4_quota_on(struct super_block *sb, int type, int format_id,
                   char *name, int remount)
{
      int err;
      struct path path;

      if (!test_opt(sb, QUOTA))
            return -EINVAL;
      /* When remounting, no checks are needed and in fact, name is NULL */
      if (remount)
            return vfs_quota_on(sb, type, format_id, name, remount);

      err = kern_path(name, LOOKUP_FOLLOW, &path);
      if (err)
            return err;

      /* Quotafile not on the same filesystem? */
      if (path.mnt->mnt_sb != sb) {
            path_put(&path);
            return -EXDEV;
      }
      /* Journaling quota? */
      if (EXT4_SB(sb)->s_qf_names[type]) {
            /* Quotafile not in fs root? */
            if (path.dentry->d_parent != sb->s_root)
                  ext4_msg(sb, KERN_WARNING,
                        "Quota file not on filesystem root. "
                        "Journaled quota will not work");
      }

      /*
       * When we journal data on quota file, we have to flush journal to see
       * all updates to the file when we bypass pagecache...
       */
      if (EXT4_SB(sb)->s_journal &&
          ext4_should_journal_data(path.dentry->d_inode)) {
            /*
             * We don't need to lock updates but journal_flush() could
             * otherwise be livelocked...
             */
            jbd2_journal_lock_updates(EXT4_SB(sb)->s_journal);
            err = jbd2_journal_flush(EXT4_SB(sb)->s_journal);
            jbd2_journal_unlock_updates(EXT4_SB(sb)->s_journal);
            if (err) {
                  path_put(&path);
                  return err;
            }
      }

      err = vfs_quota_on_path(sb, type, format_id, &path);
      path_put(&path);
      return err;
}

/* Read data from quotafile - avoid pagecache and such because we cannot afford
 * acquiring the locks... As quota files are never truncated and quota code
 * itself serializes the operations (and noone else should touch the files)
 * we don't have to be afraid of races */
static ssize_t ext4_quota_read(struct super_block *sb, int type, char *data,
                         size_t len, loff_t off)
{
      struct inode *inode = sb_dqopt(sb)->files[type];
      ext4_lblk_t blk = off >> EXT4_BLOCK_SIZE_BITS(sb);
      int err = 0;
      int offset = off & (sb->s_blocksize - 1);
      int tocopy;
      size_t toread;
      struct buffer_head *bh;
      loff_t i_size = i_size_read(inode);

      if (off > i_size)
            return 0;
      if (off+len > i_size)
            len = i_size-off;
      toread = len;
      while (toread > 0) {
            tocopy = sb->s_blocksize - offset < toread ?
                        sb->s_blocksize - offset : toread;
            bh = ext4_bread(NULL, inode, blk, 0, &err);
            if (err)
                  return err;
            if (!bh)    /* A hole? */
                  memset(data, 0, tocopy);
            else
                  memcpy(data, bh->b_data+offset, tocopy);
            brelse(bh);
            offset = 0;
            toread -= tocopy;
            data += tocopy;
            blk++;
      }
      return len;
}

/* Write to quotafile (we know the transaction is already started and has
 * enough credits) */
static ssize_t ext4_quota_write(struct super_block *sb, int type,
                        const char *data, size_t len, loff_t off)
{
      struct inode *inode = sb_dqopt(sb)->files[type];
      ext4_lblk_t blk = off >> EXT4_BLOCK_SIZE_BITS(sb);
      int err = 0;
      int offset = off & (sb->s_blocksize - 1);
      int tocopy;
      int journal_quota = EXT4_SB(sb)->s_qf_names[type] != NULL;
      size_t towrite = len;
      struct buffer_head *bh;
      handle_t *handle = journal_current_handle();

      if (EXT4_SB(sb)->s_journal && !handle) {
            ext4_msg(sb, KERN_WARNING, "Quota write (off=%llu, len=%llu)"
                  " cancelled because transaction is not started",
                  (unsigned long long)off, (unsigned long long)len);
            return -EIO;
      }
      mutex_lock_nested(&inode->i_mutex, I_MUTEX_QUOTA);
      while (towrite > 0) {
            tocopy = sb->s_blocksize - offset < towrite ?
                        sb->s_blocksize - offset : towrite;
            bh = ext4_bread(handle, inode, blk, 1, &err);
            if (!bh)
                  goto out;
            if (journal_quota) {
                  err = ext4_journal_get_write_access(handle, bh);
                  if (err) {
                        brelse(bh);
                        goto out;
                  }
            }
            lock_buffer(bh);
            memcpy(bh->b_data+offset, data, tocopy);
            flush_dcache_page(bh->b_page);
            unlock_buffer(bh);
            if (journal_quota)
                  err = ext4_handle_dirty_metadata(handle, NULL, bh);
            else {
                  /* Always do at least ordered writes for quotas */
                  err = ext4_jbd2_file_inode(handle, inode);
                  mark_buffer_dirty(bh);
            }
            brelse(bh);
            if (err)
                  goto out;
            offset = 0;
            towrite -= tocopy;
            data += tocopy;
            blk++;
      }
out:
      if (len == towrite) {
            mutex_unlock(&inode->i_mutex);
            return err;
      }
      if (inode->i_size < off+len-towrite) {
            i_size_write(inode, off+len-towrite);
            EXT4_I(inode)->i_disksize = inode->i_size;
      }
      inode->i_mtime = inode->i_ctime = CURRENT_TIME;
      ext4_mark_inode_dirty(handle, inode);
      mutex_unlock(&inode->i_mutex);
      return len - towrite;
}

#endif

static int ext4_get_sb(struct file_system_type *fs_type, int flags,
                   const char *dev_name, void *data, struct vfsmount *mnt)
{
      return get_sb_bdev(fs_type, flags, dev_name, data, ext4_fill_super,mnt);
}

static struct file_system_type ext4_fs_type = {
      .owner            = THIS_MODULE,
      .name       = "ext4",
      .get_sb           = ext4_get_sb,
      .kill_sb    = kill_block_super,
      .fs_flags   = FS_REQUIRES_DEV,
};

#ifdef CONFIG_EXT4DEV_COMPAT
static int ext4dev_get_sb(struct file_system_type *fs_type, int flags,
                    const char *dev_name, void *data,struct vfsmount *mnt)
{
      printk(KERN_WARNING "EXT4-fs (%s): Update your userspace programs "
             "to mount using ext4\n", dev_name);
      printk(KERN_WARNING "EXT4-fs (%s): ext4dev backwards compatibility "
             "will go away by 2.6.31\n", dev_name);
      return get_sb_bdev(fs_type, flags, dev_name, data, ext4_fill_super,mnt);
}

static struct file_system_type ext4dev_fs_type = {
      .owner            = THIS_MODULE,
      .name       = "ext4dev",
      .get_sb           = ext4dev_get_sb,
      .kill_sb    = kill_block_super,
      .fs_flags   = FS_REQUIRES_DEV,
};
MODULE_ALIAS("ext4dev");
#endif

static int __init init_ext4_fs(void)
{
      int err;

      err = init_ext4_system_zone();
      if (err)
            return err;
      ext4_kset = kset_create_and_add("ext4", NULL, fs_kobj);
      if (!ext4_kset)
            goto out4;
      ext4_proc_root = proc_mkdir("fs/ext4", NULL);
      err = init_ext4_mballoc();
      if (err)
            goto out3;

      err = init_ext4_xattr();
      if (err)
            goto out2;
      err = init_inodecache();
      if (err)
            goto out1;
      err = register_filesystem(&ext4_fs_type);
      if (err)
            goto out;
#ifdef CONFIG_EXT4DEV_COMPAT
      err = register_filesystem(&ext4dev_fs_type);
      if (err) {
            unregister_filesystem(&ext4_fs_type);
            goto out;
      }
#endif
      return 0;
out:
      destroy_inodecache();
out1:
      exit_ext4_xattr();
out2:
      exit_ext4_mballoc();
out3:
      remove_proc_entry("fs/ext4", NULL);
      kset_unregister(ext4_kset);
out4:
      exit_ext4_system_zone();
      return err;
}

static void __exit exit_ext4_fs(void)
{
      unregister_filesystem(&ext4_fs_type);
#ifdef CONFIG_EXT4DEV_COMPAT
      unregister_filesystem(&ext4dev_fs_type);
#endif
      destroy_inodecache();
      exit_ext4_xattr();
      exit_ext4_mballoc();
      remove_proc_entry("fs/ext4", NULL);
      kset_unregister(ext4_kset);
      exit_ext4_system_zone();
}

MODULE_AUTHOR("Remy Card, Stephen Tweedie, Andrew Morton, Andreas Dilger, Theodore Ts'o and others");
MODULE_DESCRIPTION("Fourth Extended Filesystem");
MODULE_LICENSE("GPL");
module_init(init_ext4_fs)
module_exit(exit_ext4_fs)

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