nvmet: Introduce nvmet_dsm_len() helper

Similar to the nvmet_rw_len helper.

Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
[split patch, update changelog]
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/nvme/target/io-cmd-file.c

@@ -379,8 +379,7 @@ u16 nvmet_file_parse_io_cmd(struct nvmet_req *req)
 		return 0;
 	case nvme_cmd_dsm:
 		req->execute = nvmet_file_execute_dsm;
-		req->data_len = (le32_to_cpu(cmd->dsm.nr) + 1) *
-			sizeof(struct nvme_dsm_range);
+		req->data_len = nvmet_dsm_len(req);
 		return 0;
 	case nvme_cmd_write_zeroes:
 		req->execute = nvmet_file_execute_write_zeroes;

drivers/nvme/target/nvmet.h

@@ -495,6 +495,12 @@ static inline u32 nvmet_rw_len(struct nvmet_req *req)
 			req->ns->blksize_shift;
 }
 
+static inline u32 nvmet_dsm_len(struct nvmet_req *req)
+{
+	return (le32_to_cpu(req->cmd->dsm.nr) + 1) *
+		sizeof(struct nvme_dsm_range);
+}
+
 u16 errno_to_nvme_status(struct nvmet_req *req, int errno);
 
 /* Convert a 32-bit number to a 16-bit 0's based number */