[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>
This commit is contained in:
Jens Axboe 2006-10-31 14:21:55 +01:00 committed by Linus Torvalds
parent eafa6cb18e
commit 5fccbf61be

View File

@ -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);