block: make blk-throttle preserve the issuing task on delayed bios

Make blk-throttle call bio_associate_current() on bios being delayed
such that they get issued to block layer with the original io_context.
This allows stacking blk-throttle and cfq-iosched propio policies.
bios will always be issued with the correct ioc and blkcg whether it
gets delayed by blk-throttle or not.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Tejun Heo 2012-03-05 13:15:29 -08:00 committed by Jens Axboe
parent 4f85cb96d9
commit 671058fb2a

View File

@ -894,6 +894,9 @@ bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
goto out;
}
/* bio_associate_current() needs ioc, try creating */
create_io_context(GFP_ATOMIC, q->node);
/*
* A throtl_grp pointer retrieved under rcu can be used to access
* basic fields like stats and io rates. If a group has no rules,
@ -958,6 +961,7 @@ queue_bio:
tg->io_disp[rw], tg->iops[rw],
tg->nr_queued[READ], tg->nr_queued[WRITE]);
bio_associate_current(bio);
throtl_add_bio_tg(q->td, tg, bio);
throttled = true;