[PATCH V9 8/9] nvmet: add common I/O length check helper

[Chaitanya Kulkarni <chaitanya.kulkarni@xxxxxxx>]

With the addition of zns backend now we have three different backends
with which checks for the nvmet request's transfer len and nvmet
request's sg_cnt. That leads to having duplicate code in for three
backends: generic bdev, file and generic zns.

Add a helper function to avoid the duplicate code and update the
respective backends.

Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@xxxxxxx>
---
 drivers/nvme/target/io-cmd-bdev.c |  8 +-------
 drivers/nvme/target/io-cmd-file.c |  7 +------
 drivers/nvme/target/nvmet.h       | 14 ++++++++++++++
 drivers/nvme/target/zns.c         |  7 +------
 4 files changed, 17 insertions(+), 19 deletions(-)

diff --git a/drivers/nvme/target/io-cmd-bdev.c b/drivers/nvme/target/io-cmd-bdev.c
index 562c2dd9c08c..c23a719513b0 100644
--- a/drivers/nvme/target/io-cmd-bdev.c
+++ b/drivers/nvme/target/io-cmd-bdev.c
@@ -240,16 +240,10 @@ static void nvmet_bdev_execute_rw(struct nvmet_req *req)
 	int op, i, rc;
 	struct sg_mapping_iter prot_miter;
 	unsigned int iter_flags;
-	unsigned int total_len = nvmet_rw_data_len(req) + req->metadata_len;
 
-	if (!nvmet_check_transfer_len(req, total_len))
+	if (!nvmet_continue_io(req, nvmet_rw_data_len(req) + req->metadata_len))
 		return;
 
-	if (!req->sg_cnt) {
-		nvmet_req_complete(req, 0);
-		return;
-	}
-
 	if (req->cmd->rw.opcode == nvme_cmd_write) {
 		op = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
 		if (req->cmd->rw.control & cpu_to_le16(NVME_RW_FUA))
diff --git a/drivers/nvme/target/io-cmd-file.c b/drivers/nvme/target/io-cmd-file.c
index 0abbefd9925e..e7caff221b7b 100644
--- a/drivers/nvme/target/io-cmd-file.c
+++ b/drivers/nvme/target/io-cmd-file.c
@@ -241,14 +241,9 @@ static void nvmet_file_execute_rw(struct nvmet_req *req)
 {
 	ssize_t nr_bvec = req->sg_cnt;
 
-	if (!nvmet_check_transfer_len(req, nvmet_rw_data_len(req)))
+	if (!nvmet_continue_io(req, nvmet_rw_data_len(req)))
 		return;
 
-	if (!req->sg_cnt || !nr_bvec) {
-		nvmet_req_complete(req, 0);
-		return;
-	}
-
 	if (nr_bvec > NVMET_MAX_INLINE_BIOVEC)
 		req->f.bvec = kmalloc_array(nr_bvec, sizeof(struct bio_vec),
 				GFP_KERNEL);
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index 93ebc9ae3fe4..f4f9d622df0d 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -685,4 +685,18 @@ static inline void nvmet_req_bio_put(struct nvmet_req *req, struct bio *bio)
 		bio_put(bio);
 }
 
+static inline bool nvmet_continue_io(struct nvmet_req *req,
+				     unsigned int total_len)
+{
+	if (!nvmet_check_transfer_len(req, total_len))
+		return false;
+
+	if (!req->sg_cnt) {
+		nvmet_req_complete(req, 0);
+		return false;
+	}
+
+	return true;
+}
+
 #endif /* _NVMET_H */
diff --git a/drivers/nvme/target/zns.c b/drivers/nvme/target/zns.c
index bba1d6957b6a..149bc8ce7010 100644
--- a/drivers/nvme/target/zns.c
+++ b/drivers/nvme/target/zns.c
@@ -289,14 +289,9 @@ void nvmet_bdev_execute_zone_append(struct nvmet_req *req)
 	int ret = 0, sg_cnt;
 	struct bio *bio;
 
-	if (!nvmet_check_transfer_len(req, nvmet_rw_data_len(req)))
+	if (!nvmet_continue_io(req, nvmet_rw_data_len(req)))
 		return;
 
-	if (!req->sg_cnt) {
-		nvmet_req_complete(req, 0);
-		return;
-	}
-
 	bio = nvmet_req_bio_get(req, NULL);
 	nvmet_bio_init(bio, req->ns->bdev, op, sect, NULL, NULL);
 
-- 
2.22.1