[dm-devel] [PATCH 1 of 2] DM Snapshot: remove redundant valid test

[Jonathan Brassow]

Patch name: dm-snapshot-remove-redundant-valid-test.patch

There is another valid test when we take the lock, the previous test can
be dropped.

Signed-off-by: Mikulas Patocka <mpatocka at redhat.com>
Reviewed-by: Jonathan Brassow <jbrassow at redhat.com>
Reviewed-by: Mike Snitzer <snitzer at redhat.com>

Index: linux-2.6/drivers/md/dm-snap.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-snap.c
+++ linux-2.6/drivers/md/dm-snap.c
@@ -1043,15 +1043,11 @@ static int snapshot_map(struct dm_target
 
 	chunk = sector_to_chunk(s->store, bio->bi_sector);
 
-	/* Full snapshots are not usable */
-	/* To get here the table must be live so s->active is always set. */
-	if (!s->valid)
-		return -EIO;
-
 	/* FIXME: should only take write lock if we need
 	 * to copy an exception */
 	down_write(&s->lock);
 
+	/* Full snapshots are not usable */
 	if (!s->valid) {
 		r = -EIO;
 		goto out_unlock;