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

5fccbf61 · Jens Axboe <[email protected]> · 2006-10-31 14:21:55 +01:00

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 <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Commit: 5fccbf61be2a7f32d2002b04afca4c5009612a58
Parents: eafa6cb1

Changes

1 files changed · +3 −3

File	Status	Add	Del	Content
block/cfq-iosched.c	modified	+3	−3	View file

block/cfq-iosched.c

View file

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 25c4e7e..1d9c3c7 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -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);