Commit 65c77fd9 authored Oct 22, 2012 by Jun'ichi Nomura Committed by Jens Axboe Oct 22, 2012

blkcg: stop iteration early if root_rl is the only request list



__blk_queue_next_rl() finds next request list based on blkg_list
while skipping root_blkg in the list.
OTOH, root_rl is special as it may exist even without root_blkg.

Though the later part of the function handles such a case correctly,
exiting early is good for readability of the code.

Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent 65635cbc

block/blk-cgroup.c

+3 −0

Original line number	Original line	Diff line number	Diff line
	@@ -333,6 +333,9 @@ struct request_list __blk_queue_next_rl(struct request_list rl,
	*/		*/
	if (rl == &q->root_rl) {		if (rl == &q->root_rl) {
	ent = &q->blkg_list;		ent = &q->blkg_list;
			/* There are no more block groups, hence no request lists */
			if (list_empty(ent))
			return NULL;
	} else {		} else {
	blkg = container_of(rl, struct blkcg_gq, rl);		blkg = container_of(rl, struct blkcg_gq, rl);
	ent = &blkg->q_node;		ent = &blkg->q_node;