[PATCH] dm: free minor after unlink gendisk

Minor number should be freed after del_gendisk().  Otherwise, there could
be a window where 2 registered gendisk has same minor number.
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Acked-by: Alasdair G Kergon <agk@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
[chrisw: backport to 2.6.15]
Signed-off-by: Chris Wright <chrisw@sous-sol.org>

drivers/md/dm.c

@@ -812,14 +812,16 @@ static struct mapped_device *alloc_dev(unsigned int minor, int persistent)
 
 static void free_dev(struct mapped_device *md)
 {
+	unsigned int minor = md->disk->first_minor;
+
 	if (md->frozen_bdev) {
 		thaw_bdev(md->frozen_bdev, NULL);
 		bdput(md->frozen_bdev);
 	}
-	free_minor(md->disk->first_minor);
 	mempool_destroy(md->tio_pool);
 	mempool_destroy(md->io_pool);
 	del_gendisk(md->disk);
+	free_minor(minor);
 	put_disk(md->disk);
 	blk_put_queue(md->queue);
 	kfree(md);