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Commit 32c37730 authored by Jan Kara's avatar Jan Kara Committed by Linus Torvalds
Browse files

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: default avatarJan Kara <jack@suse.cz>
Cc: Eric Sandeen <sandeen@sandeen.net>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus 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,