dm cache: actually resize cache

Commit f494a9c6b1b6dd9a9f21bbb75d9210d478eeb498 ("dm cache: cache
shrinking support") broke cache resizing support.

dm_cache_resize() is called with cache->cache_size before it gets
updated to new_size, so it is a no-op.  But the dm-cache superblock is
updated with the new_size even though the backing dm-array is not
resized.  Fix this by passing the new_size to dm_cache_resize().

Signed-off-by: Vincent Pelletier <plr.vincent@gmail.com>
Acked-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-cache-target.c

@@ -2755,7 +2755,7 @@ static int resize_cache_dev(struct cache *cache, dm_cblock_t new_size)
 {
 	int r;
 
-	r = dm_cache_resize(cache->cmd, cache->cache_size);
+	r = dm_cache_resize(cache->cmd, new_size);
 	if (r) {
 		DMERR("could not resize cache metadata");
 		return r;