nvmet: fix file discard return status

If nvmet_copy_from_sgl failed, we falsly return successful
completion status.

Fixes: d5eff33e ("nvmet: add simple file backed ns support")
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/target/io-cmd-file.c

@@ -227,22 +227,24 @@ static void nvmet_file_execute_discard(struct nvmet_req *req)
 {
 	int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
 	struct nvme_dsm_range range;
-	loff_t offset;
-	loff_t len;
-	int i, ret;
+	loff_t offset, len;
+	u16 ret;
+	int i;
 
 	for (i = 0; i <= le32_to_cpu(req->cmd->dsm.nr); i++) {
-		if (nvmet_copy_from_sgl(req, i * sizeof(range), &range,
-					sizeof(range)))
+		ret = nvmet_copy_from_sgl(req, i * sizeof(range), &range,
+					sizeof(range));
+		if (ret)
 			break;
 		offset = le64_to_cpu(range.slba) << req->ns->blksize_shift;
 		len = le32_to_cpu(range.nlb) << req->ns->blksize_shift;
-		ret = vfs_fallocate(req->ns->file, mode, offset, len);
-		if (ret)
+		if (vfs_fallocate(req->ns->file, mode, offset, len)) {
+			ret = NVME_SC_INTERNAL | NVME_SC_DNR;
 			break;
+		}
 	}
 
-	nvmet_req_complete(req, ret < 0 ? NVME_SC_INTERNAL | NVME_SC_DNR : 0);
+	nvmet_req_complete(req, ret);
 }
 
 static void nvmet_file_dsm_work(struct work_struct *w)