Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6

[mv-sheeva.git] / block / blk-throttle.c

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 381b09bb562b277620479fa92313cc6631995630..a89043a3caa416bd59f9a24486698e8d5ce30e1c 100644 (file)
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -168,7 +168,15 @@ static struct throtl_grp * throtl_find_alloc_tg(struct throtl_data *td,
         * tree of blkg (instead of traversing through hash list all
         * the time.
         */
-       tg = tg_of_blkg(blkiocg_lookup_group(blkcg, key));
+
+       /*
+        * This is the common case when there are no blkio cgroups.
+        * Avoid lookup in this case
+        */
+       if (blkcg == &blkio_root_cgroup)
+               tg = &td->root_tg;
+       else
+               tg = tg_of_blkg(blkiocg_lookup_group(blkcg, key));
 
        /* Fill in device details for root group */
        if (tg && !tg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {