1 files changed, 14 insertions, 1 deletions

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 68fe7514413d..043ddcca4abf 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -98,6 +98,7 @@ static const char *nbdcmd_to_ascii(int cmd)
         case  NBD_CMD_READ: return "read";
         case NBD_CMD_WRITE: return "write";
         case  NBD_CMD_DISC: return "disconnect";
+        case  NBD_CMD_TRIM: return "trim/discard";
         }
         return "invalid";
 }
@@ -469,7 +470,11 @@ static void nbd_handle_req(struct nbd_device *nbd, struct request *req)
 
         nbd_cmd(req) = NBD_CMD_READ;
         if (rq_data_dir(req) == WRITE) {
-                nbd_cmd(req) = NBD_CMD_WRITE;
+                if ((req->cmd_flags & REQ_DISCARD)) {
+                        WARN_ON(!(nbd->flags & NBD_FLAG_SEND_TRIM));
+                        nbd_cmd(req) = NBD_CMD_TRIM;
+                } else
+                        nbd_cmd(req) = NBD_CMD_WRITE;
                 if (nbd->flags & NBD_FLAG_READ_ONLY) {
                         dev_err(disk_to_dev(nbd->disk),
                                 "Write on read-only\n");
@@ -676,6 +681,10 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
 
                 mutex_unlock(&nbd->tx_lock);
 
+                if (nbd->flags & NBD_FLAG_SEND_TRIM)
+                        queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
+                                nbd->disk->queue);
+
                 thread = kthread_create(nbd_thread, nbd, nbd->disk->disk_name);
                 if (IS_ERR(thread)) {
                         mutex_lock(&nbd->tx_lock);
@@ -693,6 +702,7 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
                 nbd->file = NULL;
                 nbd_clear_que(nbd);
                 dev_warn(disk_to_dev(nbd->disk), "queue cleared\n");
+                queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, nbd->disk->queue);
                 if (file)
                         fput(file);
                 nbd->bytesize = 0;
@@ -811,6 +821,9 @@ static int __init nbd_init(void)
                  * Tell the block layer that we are not a rotational device
                  */
                 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, disk->queue);
+                disk->queue->limits.discard_granularity = 512;
+                disk->queue->limits.max_discard_sectors = UINT_MAX;
+                disk->queue->limits.discard_zeroes_data = 0;
         }
 
         if (register_blkdev(NBD_MAJOR, "nbd")) {