blk-mq: add a flags parameter to blk_mq_alloc_request

We already have the reserved flag, and a nowait flag awkwardly encoded as
a gfp_t.  Add a real flags argument to make the scheme more extensible and
allow for a nicer calling convention.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/nvme/host/lightnvm.c

@@ -470,7 +470,7 @@ static int nvme_nvm_submit_io(struct request_queue *q, struct nvm_rq *rqd)
 	struct bio *bio = rqd->bio;
 	struct nvme_nvm_command *cmd;
 
-	rq = blk_mq_alloc_request(q, bio_rw(bio), GFP_KERNEL, 0);
+	rq = blk_mq_alloc_request(q, bio_rw(bio), 0);
 	if (IS_ERR(rq))
 		return -ENOMEM;