Commit 5fccbf61 authored Oct 31, 2006 by Jens Axboe Committed by Linus Torvalds Oct 31, 2006

[PATCH] CFQ: request <-> request merging rr_list fixup



In very rare circumstances would we be pruning a merged request and at
the same time delete the implicated cfqq from the rr_list, and not readd
it when the merged request got added. This could cause io stalls until
that process issued io again.

Fix it up by putting the rr_list add handling into cfq_add_rq_rb(),
identical to how pruning is handled in cfq_del_rq_rb(). This fixes a
hang reproducible with fsx-linux.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

parent eafa6cb1

block/cfq-iosched.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -456,6 +456,9 @@ static void cfq_add_rq_rb(struct request *rq)
		*/
		while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL)
		cfq_dispatch_insert(cfqd->queue, __alias);

		if (!cfq_cfqq_on_rr(cfqq))
		cfq_add_cfqq_rr(cfqd, cfqq);
		}

		static inline void
		@@ -1652,9 +1655,6 @@ static void cfq_insert_request(request_queue_t q, struct request rq)

		cfq_add_rq_rb(rq);

		if (!cfq_cfqq_on_rr(cfqq))
		cfq_add_cfqq_rr(cfqd, cfqq);

		list_add_tail(&rq->queuelist, &cfqq->fifo);

		cfq_rq_enqueued(cfqd, cfqq, rq);