[PATCH] device-mapper: add dm_get_md

Add dm_get_dev() to get a mapped device given its dev_t.

Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/md/dm.c

@@ -921,6 +921,16 @@ static struct mapped_device *dm_find_md(dev_t dev)
 	return md;
 }
 
+struct mapped_device *dm_get_md(dev_t dev)
+{
+	struct mapped_device *md = dm_find_md(dev);
+
+	if (md)
+		dm_get(md);
+
+	return md;
+}
+
 void *dm_get_mdptr(dev_t dev)
 {
 	struct mapped_device *md;