block: Introduce BLK_MQ_REQ_PREEMPT

KAGA-KOKO · axboe · commit 1b6d65a0bfb5 · 2017-11-10T19:53:25.000-07:00
Set RQF_PREEMPT if BLK_MQ_REQ_PREEMPT is passed to
blk_get_request_flags().

Signed-off-by: Bart Van Assche &lt;bart.vanassche@wdc.com&gt;
Reviewed-by: Hannes Reinecke &lt;hare@suse.com&gt;
Tested-by: Martin Steigerwald &lt;martin@lichtvoll.de&gt;
Tested-by: Oleksandr Natalenko &lt;oleksandr@natalenko.name&gt;
Cc: Christoph Hellwig &lt;hch@lst.de&gt;
Cc: Ming Lei &lt;ming.lei@redhat.com&gt;
Cc: Johannes Thumshirn &lt;jthumshirn@suse.de&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
diff --git a/block/blk-core.c b/block/blk-core.c
@@ -1263,6 +1263,8 @@ static struct request *__get_request(struct request_list *rl, unsigned int op,
 	blk_rq_set_rl(rq, rl);
 	rq->cmd_flags = op;
 	rq->rq_flags = rq_flags;
+	if (flags & BLK_MQ_REQ_PREEMPT)
+		rq->rq_flags |= RQF_PREEMPT;
 
 	/* init elvpriv */
 	if (rq_flags & RQF_ELVPRIV) {
@@ -1444,7 +1446,7 @@ struct request *blk_get_request_flags(struct request_queue *q, unsigned int op,
 	struct request *req;
 
 	WARN_ON_ONCE(op & REQ_NOWAIT);
-	WARN_ON_ONCE(flags & ~BLK_MQ_REQ_NOWAIT);
+	WARN_ON_ONCE(flags & ~(BLK_MQ_REQ_NOWAIT | BLK_MQ_REQ_PREEMPT));
 
 	if (q->mq_ops) {
 		req = blk_mq_alloc_request(q, op, flags);
diff --git a/block/blk-mq.c b/block/blk-mq.c
@@ -291,6 +291,8 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
 	rq->q = data->q;
 	rq->mq_ctx = data->ctx;
 	rq->cmd_flags = op;
+	if (data->flags & BLK_MQ_REQ_PREEMPT)
+		rq->rq_flags |= RQF_PREEMPT;
 	if (blk_queue_io_stat(data->q))
 		rq->rq_flags |= RQF_IO_STAT;
 	/* do not touch atomic flags, it needs atomic ops against the timer */
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
@@ -212,6 +212,7 @@ enum {
 	BLK_MQ_REQ_NOWAIT	= (1 << 0), /* return when out of requests */
 	BLK_MQ_REQ_RESERVED	= (1 << 1), /* allocate from reserved pool */
 	BLK_MQ_REQ_INTERNAL	= (1 << 2), /* allocate internal/sched tag */
+	BLK_MQ_REQ_PREEMPT	= (1 << 3), /* set RQF_PREEMPT */
 };
 
 struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op,
