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Subject[PATCH V8 2/8] block: tracking request allocation with q_usage_counter
Date
This usage is basically same with blk-mq, so that we can
support to freeze legacy queue easily.

Also 'wake_up_all(&q->mq_freeze_wq)' has to be moved
into blk_set_queue_dying() since both legacy and blk-mq
may wait on the wait queue of .mq_freeze_wq.

Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Martin Steigerwald <martin@lichtvoll.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Cc: Bart Van Assche <Bart.VanAssche@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
block/blk-core.c | 15 +++++++++++++++
block/blk-mq.c | 7 -------
2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 048be4aa6024..900eaa8eefa6 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -610,6 +610,12 @@ void blk_set_queue_dying(struct request_queue *q)
}
spin_unlock_irq(q->queue_lock);
}
+
+ /*
+ * We need to ensure that processes currently waiting on
+ * the queue are notified as well.
+ */
+ wake_up_all(&q->mq_freeze_wq);
}
EXPORT_SYMBOL_GPL(blk_set_queue_dying);

@@ -1395,16 +1401,22 @@ 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 +1588,7 @@ 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 +1870,10 @@ 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 6fd9f86fc86d..10c1f49f663d 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -256,13 +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)
--
2.9.5
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