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ext4: fix deadlock in ext4_remount() and orphan list handling 

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@suse.cz>
Cc: Eric Sandeen <sandeen@sandeen.net>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jan Kara 2007-07-15 23:41:09 -07:00 committed by Linus Torvalds
parent 030703e49d
commit 32c3773011
1 changed files with 8 additions and 0 deletions
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8
fs/ext4/super.c
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@ -2222,12 +2222,14 @@ static void ext4_mark_recovery_complete(struct super_block * sb,
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_block * sb, int * flags, char * data)
(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,