[PATCH V2 4/6] nvmet: add Verify emulation support for bdev-ns

[Chaitanya Kulkarni <kch@nvidia.com>]

Not all devices can support verify requests which can be mapped to
the controller specific command. This patch adds a way to emulate
REQ_OP_VERIFY for NVMeOF block device namespace.

Signed-off-by: Chaitanya Kulkarni <kch@nvidia.com>
---
 drivers/nvme/target/io-cmd-bdev.c | 48 ++++++++++++++++++++++++-------
 1 file changed, 38 insertions(+), 10 deletions(-)

diff --git a/drivers/nvme/target/io-cmd-bdev.c b/drivers/nvme/target/io-cmd-bdev.c
index 82c341f90f06..aec287d3b7d7 100644
--- a/drivers/nvme/target/io-cmd-bdev.c
+++ b/drivers/nvme/target/io-cmd-bdev.c
@@ -446,35 +446,63 @@ static void nvmet_bdev_execute_write_zeroes(struct nvmet_req *req)
 	}
 }
 
-static void nvmet_bdev_execute_verify(struct nvmet_req *req)
+static void __nvmet_req_to_verify_sectors(struct nvmet_req *req,
+		sector_t *sects, sector_t *nr_sects)
 {
 	struct nvme_verify_cmd *verify = &req->cmd->verify;
+
+	*sects = le64_to_cpu(verify->slba) << (req->ns->blksize_shift - 9);
+	*nr_sects = (((sector_t)le16_to_cpu(verify->length) + 1) <<
+			(req->ns->blksize_shift - 9));
+}
+
+static void nvmet_bdev_submit_emulate_verify(struct nvmet_req *req)
+{
+	sector_t nr_sector;
+	sector_t sector;
+	int ret = 0;
+
+	__nvmet_req_to_verify_sectors(req, &sector, &nr_sector);
+	if (!nr_sector)
+		goto out;
+
+	/* blkdev_issue_verify() will automatically emulate */
+	ret = blkdev_issue_verify(req->ns->bdev, sector, nr_sector,
+			GFP_KERNEL);
+out:
+	nvmet_req_complete(req,
+		blk_to_nvme_status(req, errno_to_blk_status(ret)));
+}
+
+static void nvmet_bdev_execute_verify(struct nvmet_req *req)
+{
 	struct bio *bio = NULL;
 	sector_t nr_sector;
 	sector_t sector;
-	int ret;
+	int ret = 0;
 
 	if (!nvmet_check_transfer_len(req, 0))
 		return;
 
+	__nvmet_req_to_verify_sectors(req, &sector, &nr_sector);
+	if (!nr_sector)
+		goto out;
+
 	if (!bdev_verify_sectors(req->ns->bdev)) {
-		nvmet_req_complete(req, NVME_SC_INTERNAL | NVME_SC_DNR);
+		nvmet_bdev_submit_emulate_verify(req);
 		return;
 	}
 
-	sector = le64_to_cpu(verify->slba) << (req->ns->blksize_shift - 9);
-	nr_sector = (((sector_t)le16_to_cpu(verify->length) + 1) <<
-			(req->ns->blksize_shift - 9));
-
 	ret = __blkdev_issue_verify(req->ns->bdev, sector, nr_sector,
 			GFP_KERNEL, &bio);
-	if (bio) {
+	if (ret == 0 && bio) {
 		bio->bi_private = req;
 		bio->bi_end_io = nvmet_bio_done;
 		submit_bio(bio);
-	} else {
-		nvmet_req_complete(req, errno_to_nvme_status(req, ret));
+		return;
 	}
+out:
+	nvmet_req_complete(req, errno_to_nvme_status(req, ret));
 }
 
 u16 nvmet_bdev_parse_io_cmd(struct nvmet_req *req)
-- 
2.29.0