dm: fix memory leak in dm_create_persistent() when starting metadata update thread fails

If, in dm_create_persistent(), the call to create_singlethread_workqueue()
fails then we'll return without freeing the memory allocated to 'ps', thus
leaking sizeof(struct pstore) bytes.  This patch fixes the leak.

Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com
Acked-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/md/dm-exception-store.c b/drivers/md/dm-exception-store.c
index 3d65917..8fe81e1 100644
--- a/drivers/md/dm-exception-store.c
+++ b/drivers/md/dm-exception-store.c
@@ -623,6 +623,7 @@
 
 	ps->metadata_wq = create_singlethread_workqueue("ksnaphd");
 	if (!ps->metadata_wq) {
+		kfree(ps);
 		DMERR("couldn't start header metadata update thread");
 		return -ENOMEM;
 	}