avoid-extra-brelse-in-setup_new_flex_group_blocks

   1 ext4: avoid potential extra brelse in setup_new_flex_group_blocks()
   2
   3 From: Vasily Averin <vvs@virtuozzo.com>
   4
   5 Currently bh is set to NULL only during first iteration of for cycle,
   6 then this pointer is not cleared after end of using.
   7 Therefore rollback after errors can lead to extra brelse(bh) call,
   8 decrements bh counter and later trigger an unexpected warning in __brelse()
   9
  10 Patch moves brelse() calls in body of cycle to exclude requirement of
  11 brelse() call in rollback.
  12
  13 Fixes: 33afdcc5402d ("ext4: add a function which sets up group blocks ...")
  14 Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
  15 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  16 Cc: stable@kernel.org # 3.3+
  17 ---
  18  fs/ext4/resize.c | 8 ++------
  19  1 file changed, 2 insertions(+), 6 deletions(-)
  20
  21 diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
  22 index ebbc663d0798..c3fa30878ca8 100644
  23 --- a/fs/ext4/resize.c
  24 +++ b/fs/ext4/resize.c
  25 @@ -605,7 +605,6 @@ static int setup_new_flex_group_blocks(struct super_block *sb,
  26                 bh = bclean(handle, sb, block);
  27                 if (IS_ERR(bh)) {
  28                         err = PTR_ERR(bh);
  29 -                       bh = NULL;
  30                         goto out;
  31                 }
  32                 overhead = ext4_group_overhead_blocks(sb, group);
  33 @@ -618,9 +617,9 @@ static int setup_new_flex_group_blocks(struct super_block *sb,
  34                 ext4_mark_bitmap_end(EXT4_B2C(sbi, group_data[i].blocks_count),
  35                                      sb->s_blocksize * 8, bh->b_data);
  36                 err = ext4_handle_dirty_metadata(handle, NULL, bh);
  37 +               brelse(bh);
  38                 if (err)
  39                         goto out;
  40 -               brelse(bh);
  41
  42  handle_ib:
  43                 if (bg_flags[i] & EXT4_BG_INODE_UNINIT)
  44 @@ -635,18 +634,16 @@ static int setup_new_flex_group_blocks(struct super_block *sb,
  45                 bh = bclean(handle, sb, block);
  46                 if (IS_ERR(bh)) {
  47                         err = PTR_ERR(bh);
  48 -                       bh = NULL;
  49                         goto out;
  50                 }
  51
  52                 ext4_mark_bitmap_end(EXT4_INODES_PER_GROUP(sb),
  53                                      sb->s_blocksize * 8, bh->b_data);
  54                 err = ext4_handle_dirty_metadata(handle, NULL, bh);
  55 +               brelse(bh);
  56                 if (err)
  57                         goto out;
  58 -               brelse(bh);
  59         }
  60 -       bh = NULL;
  61
  62         /* Mark group tables in block bitmap */
  63         for (j = 0; j < GROUP_TABLE_COUNT; j++) {
  64 @@ -685,7 +682,6 @@ static int setup_new_flex_group_blocks(struct super_block *sb,
  65         }
  66
  67  out:
  68 -       brelse(bh);
  69         err2 = ext4_journal_stop(handle);
  70         if (err2 && !err)
  71                 err = err2;
  72 --
  73 2.17.1
  74
  75