fix-scheduling-in-atomic-on-group-checksum-failure

   1 ext4: fix scheduling in atomic on group checksum failure
   2
   3 From: Jan Kara <jack@suse.cz>
   4
   5 When block group checksum is wrong, we call ext4_error() while holding
   6 group spinlock from ext4_init_block_bitmap() or
   7 ext4_init_inode_bitmap() which results in scheduling while in atomic.
   8 Fix the issue by calling ext4_error() later after dropping the spinlock.
   9
  10 CC: stable@vger.kernel.org
  11 Reported-by: Dmitry Vyukov <dvyukov@google.com>
  12 Signed-off-by: Jan Kara <jack@suse.cz>
  13 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  14 Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
  15 ---
  16  fs/ext4/balloc.c | 7 ++++---
  17  fs/ext4/ialloc.c | 6 ++++--
  18  2 files changed, 8 insertions(+), 5 deletions(-)
  19
  20 diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
  21 index ec0668a60678..fe1f50fe764f 100644
  22 --- a/fs/ext4/balloc.c
  23 +++ b/fs/ext4/balloc.c
  24 @@ -191,7 +191,6 @@ static int ext4_init_block_bitmap(struct super_block *sb,
  25         /* If checksum is bad mark all blocks used to prevent allocation
  26          * essentially implementing a per-group read-only flag. */
  27         if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) {
  28 -               ext4_error(sb, "Checksum bad for group %u", block_group);
  29                 grp = ext4_get_group_info(sb, block_group);
  30                 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
  31                         percpu_counter_sub(&sbi->s_freeclusters_counter,
  32 @@ -442,14 +441,16 @@ ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
  33         }
  34         ext4_lock_group(sb, block_group);
  35         if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
  36 -
  37                 err = ext4_init_block_bitmap(sb, bh, block_group, desc);
  38                 set_bitmap_uptodate(bh);
  39                 set_buffer_uptodate(bh);
  40                 ext4_unlock_group(sb, block_group);
  41                 unlock_buffer(bh);
  42 -               if (err)
  43 +               if (err) {
  44 +                       ext4_error(sb, "Failed to init block bitmap for group "
  45 +                                  "%u: %d", block_group, err);
  46                         goto out;
  47 +               }
  48                 goto verify;
  49         }
  50         ext4_unlock_group(sb, block_group);
  51 diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
  52 index 3fcfd50a2e8a..acc0ad56bf2f 100644
  53 --- a/fs/ext4/ialloc.c
  54 +++ b/fs/ext4/ialloc.c
  55 @@ -76,7 +76,6 @@ static int ext4_init_inode_bitmap(struct super_block *sb,
  56         /* If checksum is bad mark all blocks and inodes use to prevent
  57          * allocation, essentially implementing a per-group read-only flag. */
  58         if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) {
  59 -               ext4_error(sb, "Checksum bad for group %u", block_group);
  60                 grp = ext4_get_group_info(sb, block_group);
  61                 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
  62                         percpu_counter_sub(&sbi->s_freeclusters_counter,
  63 @@ -191,8 +190,11 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
  64                 set_buffer_verified(bh);
  65                 ext4_unlock_group(sb, block_group);
  66                 unlock_buffer(bh);
  67 -               if (err)
  68 +               if (err) {
  69 +                       ext4_error(sb, "Failed to init inode bitmap for group "
  70 +                                  "%u: %d", block_group, err);
  71                         goto out;
  72 +               }
  73                 return bh;
  74         }
  75         ext4_unlock_group(sb, block_group);
  76 --
  77 2.6.2
  78
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