From: Jan Kara <jack@xxxxxxx>
ext4_orphan_add() and ext4_orphan_del() functions lock sb->s_lock with a
transaction started with ext4_mark_recovery_complete() waits for a transaction
holding sb->s_lock, thus leading to a possible deadlock. At the moment we
call ext4_mark_recovery_complete() from ext4_remount() we have done all the
work needed for remounting and thus we are safe to drop sb->s_lock before we
wait for transactions to commit. Note that at this moment we are still
guarded by s_umount lock against other remounts/umounts.
Signed-off-by: Jan Kara <jack@xxxxxxx>
Cc: Eric Sandeen <sandeen@xxxxxxxxxxx>
Cc: <linux-ext4@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/ext4/super.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff -puN fs/ext4/super.c~ext4-fix-deadlock-in-ext4_remount-and-orphan-list-handling fs/ext4/super.c
--- a/fs/ext4/super.c~ext4-fix-deadlock-in-ext4_remount-and-orphan-list-handling
+++ a/fs/ext4/super.c
@@ -2222,12 +2222,14 @@ static void ext4_mark_recovery_complete(
jbd2_journal_lock_updates(journal);
jbd2_journal_flush(journal);
+ lock_super(sb);
if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER) &&
sb->s_flags & MS_RDONLY) {
EXT4_CLEAR_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER);
sb->s_dirt = 0;
ext4_commit_super(sb, es, 1);
}
+ unlock_super(sb);
jbd2_journal_unlock_updates(journal);
}
@@ -2416,7 +2418,13 @@ static int ext4_remount (struct super_bl
(sbi->s_mount_state & EXT4_VALID_FS))
es->s_state = cpu_to_le16(sbi->s_mount_state);
+ /*
+ * We have to unlock super so that we can wait for
+ * transactions.
+ */
+ unlock_super(sb);
ext4_mark_recovery_complete(sb, es);
+ lock_super(sb);
} else {
__le32 ret;
if ((ret = EXT4_HAS_RO_COMPAT_FEATURE(sb,
_
-
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