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Commit 6ecf23af authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

block: extend queue bypassing to cover blkcg policies 



Extend queue bypassing such that dying queue is always bypassing and
blk-throttle is drained on bypass.  With blkcg policies updated to
test blk_queue_bypass() instead of blk_queue_dead(), this ensures that
no bio or request is held by or going through blkcg policies on a
bypassing queue.

This will be used to implement blkg cleanup on elevator switches and
policy changes.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent d732580b

block/blk-core.c

+8 −4
Original line number Diff line number Diff line
@@ -372,7 +372,6 @@ void blk_drain_queue(struct request_queue *q, bool drain_all) 
		if (q->elevator)

			elv_drain_elevator(q);



		if (drain_all)

		blk_throtl_drain(q);



		/*
@@ -415,8 +414,8 @@ void blk_drain_queue(struct request_queue *q, bool drain_all) 
 *

 * In bypass mode, only the dispatch FIFO queue of @q is used.  This

 * function makes @q enter bypass mode and drains all requests which were

 * issued before.  On return, it's guaranteed that no request has ELVPRIV

 * set.

 * throttled or issued before.  On return, it's guaranteed that no request

 * is being throttled or has ELVPRIV set.

 */

void blk_queue_bypass_start(struct request_queue *q)

{
@@ -461,6 +460,11 @@ void blk_cleanup_queue(struct request_queue *q) 
	queue_flag_set_unlocked(QUEUE_FLAG_DEAD, q);



	spin_lock_irq(lock);



	/* dead queue is permanently in bypass mode till released */

	q->bypass_depth++;

	queue_flag_set(QUEUE_FLAG_BYPASS, q);



	queue_flag_set(QUEUE_FLAG_NOMERGES, q);

	queue_flag_set(QUEUE_FLAG_NOXMERGES, q);

	queue_flag_set(QUEUE_FLAG_DEAD, q);

block/blk-throttle.c

+2 −2
Original line number Diff line number Diff line
@@ -310,7 +310,7 @@ static struct throtl_grp * throtl_get_tg(struct throtl_data *td) 
	struct request_queue *q = td->queue;



	/* no throttling for dead queue */

	if (unlikely(blk_queue_dead(q)))

	if (unlikely(blk_queue_bypass(q)))

		return NULL;



	rcu_read_lock();
@@ -335,7 +335,7 @@ static struct throtl_grp * throtl_get_tg(struct throtl_data *td) 
	spin_lock_irq(q->queue_lock);



	/* Make sure @q is still alive */

	if (unlikely(blk_queue_dead(q))) {

	if (unlikely(blk_queue_bypass(q))) {

		kfree(tg);

		return NULL;

	}