Resending the message as I've screwed up the mailing list address...
Honza
----- Forwarded message from Jan Kara <[email protected]> -----
From: Jan Kara <[email protected]>
To: [email protected]
Cc: Andrew Morton <[email protected]>, Mark Lord <[email protected]>
Subject: [PATCH] Fix deadlock of ext3_remount() and orphan list handling
Hi,
attached patch should fix deadlock Mark Lord has experienced
(http://lkml.org/lkml/2007/6/8/601). Please have a look whether the change
looks sane. I think so but ...
Honza
--
Jan Kara <[email protected]>
SuSE CR Labs
ext3_orphan_add() and ext3_orphan_del() functions lock sb->s_lock with
a transaction started with ext3_mark_recovery_complete() waits for
a transaction holding sb->s_lock, thus leading to a possible deadlock.
At the moment we call ext3_mark_recovery_complete() from ext3_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 <[email protected]>
diff -rupX /home/jack/.kerndiffexclude linux-2.6.22-rc4/fs/ext3/super.c linux-2.6.22-rc4-1-ext3_orphan_deadlock/fs/ext3/super.c
--- linux-2.6.22-rc4/fs/ext3/super.c 2007-06-11 12:29:06.000000000 +0200
+++ linux-2.6.22-rc4-1-ext3_orphan_deadlock/fs/ext3/super.c 2007-06-12 12:51:42.000000000 +0200
@@ -2139,12 +2139,14 @@ static void ext3_mark_recovery_complete(
journal_lock_updates(journal);
journal_flush(journal);
+ lock_super(sb);
if (EXT3_HAS_INCOMPAT_FEATURE(sb, EXT3_FEATURE_INCOMPAT_RECOVER) &&
sb->s_flags & MS_RDONLY) {
EXT3_CLEAR_INCOMPAT_FEATURE(sb, EXT3_FEATURE_INCOMPAT_RECOVER);
sb->s_dirt = 0;
ext3_commit_super(sb, es, 1);
}
+ unlock_super(sb);
journal_unlock_updates(journal);
}
@@ -2333,7 +2335,13 @@ static int ext3_remount (struct super_bl
(sbi->s_mount_state & EXT3_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);
ext3_mark_recovery_complete(sb, es);
+ lock_super(sb);
} else {
__le32 ret;
if ((ret = EXT3_HAS_RO_COMPAT_FEATURE(sb,
----- End forwarded message -----
--
Jan Kara <[email protected]>
SuSE CR Labs