md: Put the right device in md_seq_next

commit c887037 upstream.

If there are multiple arrays in system and one mddevice is marked
with MD_DELETED and md_seq_next() is called in the middle of removal
then it _get()s proper device but it may _put() deleted one. As a result,
active counter may never be zeroed for mddevice and it cannot
be removed.

Put the device which has been _get with previous md_seq_next() call.

Cc: stable@vger.kernel.org
Fixes: 12a6caf ("md: only delete entries from all_mddevs when the disk is freed")
Reported-by: AceLan Kao <acelan@gmail.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217798
Cc: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230914152416.10819-1-mariusz.tkaczyk@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/md/md.c

@@ -8214,7 +8214,7 @@ static void *md_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 	spin_unlock(&all_mddevs_lock);
 
 	if (to_put)
-		mddev_put(mddev);
+		mddev_put(to_put);
 	return next_mddev;
 
 }