block: Introduce BLK_MQ_REQ_PREEMPT

Set RQF_PREEMPT if BLK_MQ_REQ_PREEMPT is passed to
blk_get_request_flags().

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Martin Steigerwald <martin@lichtvoll.de>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-core.c b/block/blk-core.c
index 0f7093d..17eed16 100644 (file)
--- 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
index 7173d4b..e218767 100644 (file)
--- 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
index 4ae987c..82b5660 100644 (file)
--- 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,