engines/io_uring_cmd: do not send data buffer for write zeroes

For write zeroes commands, do not send a data bufffer address. If we do send an address, the driver will try to carry out DMA mapping and encounter driver mdts limitations which do not apply to write zeroes commands. This lets us send large write zeroes commands to deallocate the device with the deac=1. This is only done for the non-vectored IO case. For the vectored IO case, the driver requires data buffer addresses to be sent. Regardless it does not make sense to use vectored IO for write zeroes. Signed-off-by: Vincent Fu <[email protected]>
axboe · Oct 28, 2024 · a191635 · a191635
1 parent dfc79b1
commit a191635
Showing 1 changed file with 5 additions and 1 deletion.
diff --git a/engines/nvme.c b/engines/nvme.c
@@ -406,7 +406,11 @@ int fio_nvme_uring_cmd_prep(struct nvme_uring_cmd *cmd, struct io_u *io_u,
 		cmd->addr = (__u64)(uintptr_t)iov;
 		cmd->data_len = 1;
 	} else {
-		cmd->addr = (__u64)(uintptr_t)io_u->xfer_buf;
+		/* no buffer for write zeroes */
+		if (cmd->opcode != nvme_cmd_write_zeroes)
+			cmd->addr = (__u64)(uintptr_t)io_u->xfer_buf;
+		else
+			cmd->addr = (__u64)(uintptr_t)NULL;
 		cmd->data_len = io_u->xfer_buflen;
 	}
 	if (data->lba_shift && data->ms) {