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>

1 files changed, 2 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;