make-fsync-to-sync-parent-dir-in-no-journal-for-real-this-time

   1 ext4: make fsync to sync parent dir in no-journal for real this time
   2
   3 From: Lukas Czerner <lczerner@redhat.com>
   4
   5 Previously commit 14ece1028b3ed53ffec1b1213ffc6acaf79ad77c added a
   6 support for for syncing parent directory of newly created inodes to
   7 make sure that the inode is not lost after a power failure in
   8 no-journal mode.
   9
  10 However this does not work in majority of cases, namely:
  11  - if the directory has inline data
  12  - if the directory is already indexed
  13  - if the directory already has at least one block and:
  14         - the new entry fits into it
  15         - or we've successfully converted it to indexed
  16
  17 So in those cases we might lose the inode entirely even after fsync in
  18 the no-journal mode. This also includes ext2 default mode obviously.
  19
  20 I've noticed this while running xfstest generic/321 and even though the
  21 test should fail (we need to run fsck after a crash in no-journal mode)
  22 I could not find a newly created entries even when if it was fsynced
  23 before.
  24
  25 Fix this by adjusting the ext4_add_entry() successful exit paths to set
  26 the inode EXT4_STATE_NEWENTRY so that fsync has the chance to fsync the
  27 parent directory as well.
  28
  29 Signed-off-by: Lukas Czerner <lczerner@redhat.com>
  30 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  31 Reviewed-by: Jan Kara <jack@suse.cz>
  32 Cc: Frank Mayhar <fmayhar@google.com>
  33 Cc: stable@vger.kernel.org
  34 ---
  35  fs/ext4/namei.c | 20 +++++++++++---------
  36  1 file changed, 11 insertions(+), 9 deletions(-)
  37
  38 diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
  39 index efb64ae..23a0b9b 100644
  40 --- a/fs/ext4/namei.c
  41 +++ b/fs/ext4/namei.c
  42 @@ -1864,7 +1864,7 @@ static int ext4_add_entry(handle_t *handle, struct dentry *dentry,
  43                           struct inode *inode)
  44  {
  45         struct inode *dir = dentry->d_parent->d_inode;
  46 -       struct buffer_head *bh;
  47 +       struct buffer_head *bh = NULL;
  48         struct ext4_dir_entry_2 *de;
  49         struct ext4_dir_entry_tail *t;
  50         struct super_block *sb;
  51 @@ -1888,14 +1888,14 @@ static int ext4_add_entry(handle_t *handle, struct dentry *dentry,
  52                         return retval;
  53                 if (retval == 1) {
  54                         retval = 0;
  55 -                       return retval;
  56 +                       goto out;
  57                 }
  58         }
  59
  60         if (is_dx(dir)) {
  61                 retval = ext4_dx_add_entry(handle, dentry, inode);
  62                 if (!retval || (retval != ERR_BAD_DX_DIR))
  63 -                       return retval;
  64 +                       goto out;
  65                 ext4_clear_inode_flag(dir, EXT4_INODE_INDEX);
  66                 dx_fallback++;
  67                 ext4_mark_inode_dirty(handle, dir);
  68 @@ -1907,14 +1907,15 @@ static int ext4_add_entry(handle_t *handle, struct dentry *dentry,
  69                         return PTR_ERR(bh);
  70
  71                 retval = add_dirent_to_buf(handle, dentry, inode, NULL, bh);
  72 -               if (retval != -ENOSPC) {
  73 -                       brelse(bh);
  74 -                       return retval;
  75 -               }
  76 +               if (retval != -ENOSPC)
  77 +                       goto out;
  78
  79                 if (blocks == 1 && !dx_fallback &&
  80 -                   EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_DIR_INDEX))
  81 -                       return make_indexed_dir(handle, dentry, inode, bh);
  82 +                   EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_DIR_INDEX)) {
  83 +                       retval = make_indexed_dir(handle, dentry, inode, bh);
  84 +                       bh = NULL; /* make_indexed_dir releases bh */
  85 +                       goto out;
  86 +               }
  87                 brelse(bh);
  88         }
  89         bh = ext4_append(handle, dir, &block);
  90 @@ -1930,6 +1931,7 @@ static int ext4_add_entry(handle_t *handle, struct dentry *dentry,
  91         }
  92
  93         retval = add_dirent_to_buf(handle, dentry, inode, de, bh);
  94 +out:
  95         brelse(bh);
  96         if (retval == 0)
  97                 ext4_set_inode_state(inode, EXT4_STATE_NEWENTRY);