From: Ming Lei <ming....@redhat.com>
This patch makes it possible to pause request allocation for
the legacy block layer by calling blk_mq_freeze_queue() and
blk_mq_unfreeze_queue().
Signed-off-by: Ming Lei <ming....@redhat.com>
[ bvanassche: Combined two patches into one, edited a comment and made sure
REQ_NOWAIT is handled properly in blk_old_get_request() ]
Signed-off-by: Bart Van Assche <bart.vanass...@wdc.com>
Reviewed-by: Christoph Hellwig <h...@lst.de>
Cc: Ming Lei <ming....@redhat.com>
Cc: Hannes Reinecke <h...@suse.com>
Cc: Johannes Thumshirn <jthumsh...@suse.de>
---
block/blk-core.c | 12 ++++++++++++
block/blk-mq.c | 10 ++--------
2 files changed, 14 insertions(+), 8 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index 048be4aa6024..0343c7574378 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -610,6 +610,9 @@ void blk_set_queue_dying(struct request_queue *q)
}
spin_unlock_irq(q->queue_lock);
}
+
+ /* Make blk_queue_enter() reexamine the DYING flag. */
+ wake_up_all(&q->mq_freeze_wq);
}
EXPORT_SYMBOL_GPL(blk_set_queue_dying);
@@ -1395,16 +1398,22 @@ static struct request *blk_old_get_request(struct
request_queue *q,
unsigned int op, gfp_t gfp_mask)
{
struct request *rq;
+ int ret = 0;
WARN_ON_ONCE(q->mq_ops);
/* create ioc upfront */
create_io_context(gfp_mask, q->node);
+ ret = blk_queue_enter(q, !(gfp_mask & __GFP_DIRECT_RECLAIM) ||
+ (op & REQ_NOWAIT));
+ if (ret)
+ return ERR_PTR(ret);
spin_lock_irq(q->queue_lock);
rq = get_request(q, op, NULL, gfp_mask);
if (IS_ERR(rq)) {
spin_unlock_irq(q->queue_lock);
+ blk_queue_exit(q);
return rq;
}
@@ -1576,6 +1585,7 @@ void __blk_put_request(struct request_queue *q, struct
request *req)
blk_free_request(rl, req);
freed_request(rl, sync, rq_flags);
blk_put_rl(rl);
+ blk_queue_exit(q);
}
}
EXPORT_SYMBOL_GPL(__blk_put_request);
@@ -1857,8 +1867,10 @@ static blk_qc_t blk_queue_bio(struct request_queue *q,
struct bio *bio)
* Grab a free request. This is might sleep but can not fail.
* Returns with the queue unlocked.
*/
+ blk_queue_enter_live(q);
req = get_request(q, bio->bi_opf, bio, GFP_NOIO);
if (IS_ERR(req)) {
+ blk_queue_exit(q);
__wbt_done(q->rq_wb, wb_acct);
if (PTR_ERR(req) == -ENOMEM)
bio->bi_status = BLK_STS_RESOURCE;
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 7f01d69879d6..ebf85e270509 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -125,7 +125,8 @@ void blk_freeze_queue_start(struct request_queue *q)
freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
if (freeze_depth == 1) {
percpu_ref_kill(&q->q_usage_counter);
- blk_mq_run_hw_queues(q, false);
+ if (q->mq_ops)
+ blk_mq_run_hw_queues(q, false);
}
}
EXPORT_SYMBOL_GPL(blk_freeze_queue_start);
@@ -255,13 +256,6 @@ void blk_mq_wake_waiters(struct request_queue *q)
queue_for_each_hw_ctx(q, hctx, i)
if (blk_mq_hw_queue_mapped(hctx))
blk_mq_tag_wakeup_all(hctx->tags, true);
-
- /*
- * If we are called because the queue has now been marked as
- * dying, we need to ensure that processes currently waiting on
- * the queue are notified as well.
- */
- wake_up_all(&q->mq_freeze_wq);
}
bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
--
2.14.1
