[PATCH V6 5/6] nvmet: add bio get helper for different backends

[Chaitanya Kulkarni]

With the addition of the zns backend now we have three different
backends with inline bio optimization. That leads to having
duplicate code in for allocating or initializing the bio in all
three backends: generic bdev, passsthru, and generic zns.

Add a helper function to reduce the duplicate code such that helper
function accepts the bi_end_io callback which gets initialize for the
non-inline bio_alloc() case. This is due to the special case needed for
the passthru backend non-inline bio allocation bio_alloc() where we set
the bio->bi_end_io = bio_put, having this parameter avoids the extra
branch in the passthru fast path. For rest of the backends, we set the
same bi_end_io callback for inline and non-inline cases, that is for
generic bdev we set to nvmet_bio_done() and for generic zns we set to
NULL.                            

Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni at wdc.com>
---
 drivers/nvme/target/io-cmd-bdev.c |  7 +------
 drivers/nvme/target/nvmet.h       | 16 ++++++++++++++++
 drivers/nvme/target/passthru.c    |  8 +-------
 drivers/nvme/target/zns.c         |  8 +-------
 4 files changed, 19 insertions(+), 20 deletions(-)

diff --git a/drivers/nvme/target/io-cmd-bdev.c b/drivers/nvme/target/io-cmd-bdev.c
index 6178ef643962..72746e29cb0d 100644
--- a/drivers/nvme/target/io-cmd-bdev.c
+++ b/drivers/nvme/target/io-cmd-bdev.c
@@ -266,12 +266,7 @@ static void nvmet_bdev_execute_rw(struct nvmet_req *req)
 
 	sector = nvmet_lba_to_sect(req->ns, req->cmd->rw.slba);
 
-	if (req->transfer_len <= NVMET_MAX_INLINE_DATA_LEN) {
-		bio = &req->b.inline_bio;
-		bio_init(bio, req->inline_bvec, ARRAY_SIZE(req->inline_bvec));
-	} else {
-		bio = bio_alloc(GFP_KERNEL, min(sg_cnt, BIO_MAX_PAGES));
-	}
+	bio = nvmet_req_bio_get(req, NULL);
 	bio_set_dev(bio, req->ns->bdev);
 	bio->bi_iter.bi_sector = sector;
 	bio->bi_private = req;
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index 7361665585a2..3fc84f79cce1 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -652,4 +652,20 @@ nvmet_bdev_execute_zone_append(struct nvmet_req *req)
 }
 #endif /* CONFIG_BLK_DEV_ZONED */
 
+static inline struct bio *nvmet_req_bio_get(struct nvmet_req *req,
+					    bio_end_io_t *bi_end_io)
+{
+	struct bio *bio;
+
+	if (req->transfer_len <= NVMET_MAX_INLINE_DATA_LEN) {
+		bio = &req->b.inline_bio;
+		bio_init(bio, req->inline_bvec, ARRAY_SIZE(req->inline_bvec));
+		return bio;
+	}
+
+	bio = bio_alloc(GFP_KERNEL, req->sg_cnt);
+	bio->bi_end_io = bi_end_io;
+	return bio;
+}
+
 #endif /* _NVMET_H */
diff --git a/drivers/nvme/target/passthru.c b/drivers/nvme/target/passthru.c
index b9776fc8f08f..54f765b566ee 100644
--- a/drivers/nvme/target/passthru.c
+++ b/drivers/nvme/target/passthru.c
@@ -194,13 +194,7 @@ static int nvmet_passthru_map_sg(struct nvmet_req *req, struct request *rq)
 	if (req->sg_cnt > BIO_MAX_PAGES)
 		return -EINVAL;
 
-	if (req->transfer_len <= NVMET_MAX_INLINE_DATA_LEN) {
-		bio = &req->p.inline_bio;
-		bio_init(bio, req->inline_bvec, ARRAY_SIZE(req->inline_bvec));
-	} else {
-		bio = bio_alloc(GFP_KERNEL, min(req->sg_cnt, BIO_MAX_PAGES));
-		bio->bi_end_io = bio_put;
-	}
+	bio = nvmet_req_bio_get(req, bio_put);
 	bio->bi_opf = req_op(rq);
 
 	for_each_sg(req->sg, sg, req->sg_cnt, i) {
diff --git a/drivers/nvme/target/zns.c b/drivers/nvme/target/zns.c
index 3f9a5ac6a6c5..058da4a2012b 100644
--- a/drivers/nvme/target/zns.c
+++ b/drivers/nvme/target/zns.c
@@ -309,13 +309,7 @@ void nvmet_bdev_execute_zone_append(struct nvmet_req *req)
 		return;
 	}
 
-	if (req->transfer_len <= NVMET_MAX_INLINE_DATA_LEN) {
-		bio = &req->b.inline_bio;
-		bio_init(bio, req->inline_bvec, ARRAY_SIZE(req->inline_bvec));
-	} else {
-		bio = bio_alloc(GFP_KERNEL, req->sg_cnt);
-	}
-
+	bio = nvmet_req_bio_get(req, NULL);
 	bio_set_dev(bio, req->ns->bdev);
 	bio->bi_iter.bi_sector = sect;
 	bio->bi_opf = REQ_OP_ZONE_APPEND | REQ_SYNC | REQ_IDLE;
-- 
2.22.1