nvmet: add support for the Write Zeroes command

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. Allow write zeroes operation
to deallocate the LBAs when calling __blkdev_issue_zeroout.

Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@hgst.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

2 files changed, 31 insertions, 1 deletions

diff --git a/drivers/nvme/target/admin-cmd.c b/drivers/nvme/target/admin-cmd.c
index 7ab9c9381b98..383ea10b97cc 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 c4dc9ea8ade0..4195115c7e54 100644
--- a/drivers/nvme/target/io-cmd.c
+++ b/drivers/nvme/target/io-cmd.c
@@ -170,6 +170,32 @@ 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, true))
+                status = NVME_SC_INTERNAL | NVME_SC_DNR;
+
+        if (bio) {
+                bio->bi_private = req;
+                bio->bi_end_io = nvmet_bio_done;
+                submit_bio(bio);
+        } else {
+                nvmet_req_complete(req, status);
+        }
+}
+
 int nvmet_parse_io_cmd(struct nvmet_req *req)
 {
         struct nvme_command *cmd = req->cmd;
@@ -207,6 +233,9 @@ 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;