Commit 32c37730 authored Jul 15, 2007 by Jan Kara Committed by Linus Torvalds Jul 16, 2007

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>

parent 030703e4

fs/ext4/super.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -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,

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