[PATCH 5/5] nvmet: add support for the Write Zeroes command

[Chaitanya Kulkarni]

Add support for handling write zeroes command on target.
Call into __blkdev_issue_zeroout, which the block layer expands into the
best suitable variant of zeroing the LBAs.

Signed-off-by: Chaitanya Kulkarni <chaitanya.kulka...@hgst.com>
---
 drivers/nvme/target/admin-cmd.c |  3 ++-
 drivers/nvme/target/io-cmd.c    | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/target/admin-cmd.c b/drivers/nvme/target/admin-cmd.c
index 6fe4c48..ec1ad2a 100644
--- a/drivers/nvme/target/admin-cmd.c
+++ b/drivers/nvme/target/admin-cmd.c
@@ -237,7 +237,8 @@ static void nvmet_execute_identify_ctrl(struct nvmet_req 
*req)
        id->maxcmd = cpu_to_le16(NVMET_MAX_CMD);
 
        id->nn = cpu_to_le32(ctrl->subsys->max_nsid);
-       id->oncs = cpu_to_le16(NVME_CTRL_ONCS_DSM);
+       id->oncs = cpu_to_le16(NVME_CTRL_ONCS_DSM |
+                       NVME_CTRL_ONCS_WRITE_ZEROES);
 
        /* XXX: don't report vwc if the underlying device is write through */
        id->vwc = NVME_CTRL_VWC_PRESENT;
diff --git a/drivers/nvme/target/io-cmd.c b/drivers/nvme/target/io-cmd.c
index ef52b1e..7d4b022 100644
--- a/drivers/nvme/target/io-cmd.c
+++ b/drivers/nvme/target/io-cmd.c
@@ -172,6 +172,37 @@ static void nvmet_execute_dsm(struct nvmet_req *req)
        }
 }
 
+static void nvmet_execute_write_zeroes(struct nvmet_req *req)
+{
+       struct nvme_write_zeroes_cmd *write_zeroes = &req->cmd->write_zeroes;
+       struct bio *bio = NULL;
+       u16 status = NVME_SC_SUCCESS;
+       sector_t sector;
+       sector_t nr_sector;
+
+       sector = le64_to_cpu(write_zeroes->slba) <<
+               (req->ns->blksize_shift - 9);
+       nr_sector = (((sector_t)le32_to_cpu(write_zeroes->length)) <<
+               (req->ns->blksize_shift - 9)) + 1;
+
+       if (__blkdev_issue_zeroout(req->ns->bdev, sector, nr_sector,
+                               GFP_KERNEL, &bio, false))
+               status = NVME_SC_INTERNAL | NVME_SC_DNR;
+
+       if (bio) {
+               bio->bi_private = req;
+               bio->bi_end_io = nvmet_bio_done;
+               if (status) {
+                       bio->bi_error = -EIO;
+                       bio_endio(bio);
+               } else {
+                       submit_bio(bio);
+               }
+       } else {
+               nvmet_req_complete(req, status);
+       }
+}
+
 int nvmet_parse_io_cmd(struct nvmet_req *req)
 {
        struct nvme_command *cmd = req->cmd;
@@ -209,6 +240,9 @@ int nvmet_parse_io_cmd(struct nvmet_req *req)
                req->data_len = le32_to_cpu(cmd->dsm.nr + 1) *
                        sizeof(struct nvme_dsm_range);
                return 0;
+       case nvme_cmd_write_zeroes:
+               req->execute = nvmet_execute_write_zeroes;
+               return 0;
        default:
                pr_err("nvmet: unhandled cmd %d\n", cmd->common.opcode);
                return NVME_SC_INVALID_OPCODE | NVME_SC_DNR;
-- 
1.8.3.1

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