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>
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 08b7ab2..4ba1418 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -894,6 +894,9 @@
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 @@
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;