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

[Chaitanya Kulkarni]

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. We add a new
workqueue to offload the emulation.

Signed-off-by: Chaitanya Kulkarni <kch at nvidia.com>
---
 drivers/nvme/target/core.c        | 14 ++++++--
 drivers/nvme/target/io-cmd-bdev.c | 56 +++++++++++++++++++++++++------
 drivers/nvme/target/nvmet.h       |  4 ++-
 3 files changed, 61 insertions(+), 13 deletions(-)

diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 90e75324dae0..b701eeaf156a 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -16,6 +16,7 @@
 #include "nvmet.h"
 
 struct workqueue_struct *buffered_io_wq;
+struct workqueue_struct *verify_wq;
 struct workqueue_struct *zbd_wq;
 static const struct nvmet_fabrics_ops *nvmet_transports[NVMF_TRTYPE_MAX];
 static DEFINE_IDA(cntlid_ida);
@@ -1611,10 +1612,16 @@ static int __init nvmet_init(void)
 
 	nvmet_ana_group_enabled[NVMET_DEFAULT_ANA_GRPID] = 1;
 
-	zbd_wq = alloc_workqueue("nvmet-zbd-wq", WQ_MEM_RECLAIM, 0);
-	if (!zbd_wq)
+	verify_wq = alloc_workqueue("nvmet-verify-wq", WQ_MEM_RECLAIM, 0);
+	if (!verify_wq)
 		return -ENOMEM;
 
+	zbd_wq = alloc_workqueue("nvmet-zbd-wq", WQ_MEM_RECLAIM, 0);
+	if (!zbd_wq) {
+		error = -ENOMEM;
+		goto out_free_verify_work_queue;
+	}
+
 	buffered_io_wq = alloc_workqueue("nvmet-buffered-io-wq",
 			WQ_MEM_RECLAIM, 0);
 	if (!buffered_io_wq) {
@@ -1645,6 +1652,8 @@ static int __init nvmet_init(void)
 	destroy_workqueue(buffered_io_wq);
 out_free_zbd_work_queue:
 	destroy_workqueue(zbd_wq);
+out_free_verify_work_queue:
+	destroy_workqueue(verify_wq);
 	return error;
 }
 
@@ -1656,6 +1665,7 @@ static void __exit nvmet_exit(void)
 	destroy_workqueue(nvmet_wq);
 	destroy_workqueue(buffered_io_wq);
 	destroy_workqueue(zbd_wq);
+	destroy_workqueue(verify_wq);
 
 	BUILD_BUG_ON(sizeof(struct nvmf_disc_rsp_page_entry) != 1024);
 	BUILD_BUG_ON(sizeof(struct nvmf_disc_rsp_page_hdr) != 1024);
diff --git a/drivers/nvme/target/io-cmd-bdev.c b/drivers/nvme/target/io-cmd-bdev.c
index 6687e2665e26..721c8571a2da 100644
--- a/drivers/nvme/target/io-cmd-bdev.c
+++ b/drivers/nvme/target/io-cmd-bdev.c
@@ -447,35 +447,71 @@ 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_emulate_verify_work(struct work_struct *w)
+{
+	struct nvmet_req *req = container_of(w, struct nvmet_req, b.work);
+	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_submit_emulate_verify(struct nvmet_req *req)
+{
+	INIT_WORK(&req->b.work, nvmet_bdev_emulate_verify_work);
+	queue_work(verify_wq, &req->b.work);
+}
+
+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;
+
+	/* offload emulation */
 	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)
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index 69818752a33a..96e3f6eb4fef 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -326,7 +326,8 @@ struct nvmet_req {
 	struct bio_vec		inline_bvec[NVMET_MAX_INLINE_BIOVEC];
 	union {
 		struct {
-			struct bio      inline_bio;
+			struct bio		inline_bio;
+			struct work_struct	work;
 		} b;
 		struct {
 			bool			mpool_alloc;
@@ -365,6 +366,7 @@ struct nvmet_req {
 };
 
 extern struct workqueue_struct *buffered_io_wq;
+extern struct workqueue_struct *verify_wq;
 extern struct workqueue_struct *zbd_wq;
 extern struct workqueue_struct *nvmet_wq;
 
-- 
2.29.0