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ext3: fix deadlock in ext3_remount() and orphan list handling
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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 <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>
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Jan Kara authored and Linus Torvalds committed Jul 16, 2007
1 parent 8b3b295 commit 030703e
Showing 1 changed file with 8 additions and 0 deletions.
8 changes: 8 additions & 0 deletions fs/ext3/super.c
Original file line number Diff line number Diff line change
Expand Up @@ -2147,12 +2147,14 @@ static void ext3_mark_recovery_complete(struct super_block * sb,

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);
}

Expand Down Expand Up @@ -2341,7 +2343,13 @@ static int ext3_remount (struct super_block * sb, int * flags, char * data)
(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,
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