blk-throttle: Use blk_plug in throttle dispatch

[linux-2.6-block.git] / block / blk-throttle.c

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 381b09bb562b277620479fa92313cc6631995630..658ee505315bd4025035af2e76f7ccf5fe0ec4b9 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)) {
@@ -762,6 +770,7 @@ static int throtl_dispatch(struct request_queue *q)
        unsigned int nr_disp = 0;
        struct bio_list bio_list_on_stack;
        struct bio *bio;
+       struct blk_plug plug;
 
        spin_lock_irq(q->queue_lock);
 
@@ -790,9 +799,10 @@ out:
         * immediate dispatch
         */
        if (nr_disp) {
+               blk_start_plug(&plug);
                while((bio = bio_list_pop(&bio_list_on_stack)))
                        generic_make_request(bio);
-               blk_unplug(q);
+               blk_finish_plug(&plug);
        }
        return nr_disp;
 }