clean-mmp-status-on-remount-ro

   1 ext4: clear mmp sequence number when remounting read-only
   2
   3 Previously, when an MMP-protected file system is remounted read-only,
   4 the kmmpd thread would exit the next time it woke up (a few seconds
   5 later), without resetting the MMP sequence number back to
   6 EXT4_MMP_SEQ_CLEAN.
   7
   8 Fix this by explicitly killing the MMP thread when the file system is
   9 remounted read-only.
  10
  11 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  12 Cc: Andreas Dilger <adilger@dilger.ca>
  13 ---
  14  fs/ext4/mmp.c   | 7 ++-----
  15  fs/ext4/super.c | 2 ++
  16  2 files changed, 4 insertions(+), 5 deletions(-)
  17
  18 diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c
  19 index 27b9a76a0dfa..638ad4743477 100644
  20 --- a/fs/ext4/mmp.c
  21 +++ b/fs/ext4/mmp.c
  22 @@ -186,11 +186,8 @@ static int kmmpd(void *data)
  23                         goto exit_thread;
  24                 }
  25
  26 -               if (sb_rdonly(sb)) {
  27 -                       ext4_warning(sb, "kmmpd being stopped since filesystem "
  28 -                                    "has been remounted as readonly.");
  29 -                       goto exit_thread;
  30 -               }
  31 +               if (sb_rdonly(sb))
  32 +                       break;
  33
  34                 diff = jiffies - last_update_time;
  35                 if (diff < mmp_update_interval * HZ)
  36 diff --git a/fs/ext4/super.c b/fs/ext4/super.c
  37 index 90d0e113a174..38b5d2a22a63 100644
  38 --- a/fs/ext4/super.c
  39 +++ b/fs/ext4/super.c
  40 @@ -5219,6 +5219,8 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
  41
  42                         if (sbi->s_journal)
  43                                 ext4_mark_recovery_complete(sb, es);
  44 +                       if (sbi->s_mmp_tsk)
  45 +                               kthread_stop(sbi->s_mmp_tsk);
  46                 } else {
  47                         /* Make sure we can mount this feature set readwrite */
  48                         if (ext4_has_feature_readonly(sb) ||