Merge branch 'for-linus' of git://git.kernel.dk/linux-block

Pull block fixes from Jens Axboe:
"Four small fixes.

Three of them fix the same error in NVMe, in loop, fc, and rdma
respectively. The last fix from Ming fixes a regression in this
series, where our bvec gap logic was wrong and causes an oops on
NVMe for certain conditions"

* 'for-linus' of git://git.kernel.dk/linux-block:
block: fix bio_will_gap() for first bvec with offset
nvme-fc: Fix sqsize wrong assignment based on ctrl MQES capability
nvme-rdma: Fix sqsize wrong assignment based on ctrl MQES capability
nvme-loop: Fix sqsize wrong assignment based on ctrl MQES capability

drivers/nvme/host/fc.c

···
 	}
 
 	ctrl->ctrl.sqsize =
-		min_t(int, NVME_CAP_MQES(ctrl->cap) + 1, ctrl->ctrl.sqsize);
+		min_t(int, NVME_CAP_MQES(ctrl->cap), ctrl->ctrl.sqsize);
 
 	error = nvme_enable_ctrl(&ctrl->ctrl, ctrl->cap);
 	if (error)

drivers/nvme/host/rdma.c

···
 	}
 
 	ctrl->ctrl.sqsize =
-		min_t(int, NVME_CAP_MQES(ctrl->cap) + 1, ctrl->ctrl.sqsize);
+		min_t(int, NVME_CAP_MQES(ctrl->cap), ctrl->ctrl.sqsize);
 
 	error = nvme_enable_ctrl(&ctrl->ctrl, ctrl->cap);
 	if (error)

drivers/nvme/target/loop.c

···
 	}
 
 	ctrl->ctrl.sqsize =
-		min_t(int, NVME_CAP_MQES(ctrl->cap) + 1, ctrl->ctrl.sqsize);
+		min_t(int, NVME_CAP_MQES(ctrl->cap), ctrl->ctrl.sqsize);
 
 	error = nvme_enable_ctrl(&ctrl->ctrl, ctrl->cap);
 	if (error)

include/linux/blkdev.h

···
 	return true;
 }
 
-static inline bool bio_will_gap(struct request_queue *q, struct bio *prev,
-			 struct bio *next)
+static inline bool bio_will_gap(struct request_queue *q,
+				struct request *prev_rq,
+				struct bio *prev,
+				struct bio *next)
 {
 	if (bio_has_data(prev) && queue_virt_boundary(q)) {
 		struct bio_vec pb, nb;
 
+		/*
+		 * don't merge if the 1st bio starts with non-zero
+		 * offset, otherwise it is quite difficult to respect
+		 * sg gap limit. We work hard to merge a huge number of small
+		 * single bios in case of mkfs.
+		 */
+		if (prev_rq)
+			bio_get_first_bvec(prev_rq->bio, &pb);
+		else
+			bio_get_first_bvec(prev, &pb);
+		if (pb.bv_offset)
+			return true;
+
+		/*
+		 * We don't need to worry about the situation that the
+		 * merged segment ends in unaligned virt boundary:
+		 *
+		 * - if 'pb' ends aligned, the merged segment ends aligned
+		 * - if 'pb' ends unaligned, the next bio must include
+		 *   one single bvec of 'nb', otherwise the 'nb' can't
+		 *   merge with 'pb'
+		 */
 		bio_get_last_bvec(prev, &pb);
 		bio_get_first_bvec(next, &nb);
 
···
 
 static inline bool req_gap_back_merge(struct request *req, struct bio *bio)
 {
-	return bio_will_gap(req->q, req->biotail, bio);
+	return bio_will_gap(req->q, req, req->biotail, bio);
 }
 
 static inline bool req_gap_front_merge(struct request *req, struct bio *bio)
 {
-	return bio_will_gap(req->q, bio, req->bio);
+	return bio_will_gap(req->q, NULL, bio, req->bio);
 }
 
 int kblockd_schedule_work(struct work_struct *work);