ioctl: Rearrange members in nvme_fw_download_args

Avoid any holes in the struct by rearranging the members. Also add the
attribute packed to struct definition to reduce ABI breakage.

struct nvme_fw_download_args {
        int                        args_size;            /*     0     4 */
        int                        fd;                   /*     4     4 */
        __u32 *                    result;               /*     8     8 */
        __u32                      timeout;              /*    16     4 */
        __u32                      offset;               /*    20     4 */
        void *                     data;                 /*    24     8 */
        __u32                      data_len;             /*    32     4 */

        /* size: 40, cachelines: 1, members: 7 */
        /* padding: 4 */
        /* last cacheline: 40 bytes */
} __attribute__((__aligned__(8)));

Signed-off-by: Daniel Wagner <[email protected]>

Author: dwsuse

src/nvme/ioctl.h

@@ -2850,21 +2850,21 @@ static inline int nvme_ns_detach_ctrls(int fd, __u32 nsid,
 /**
  * nvme_fw_download_args - Arguments for the NVMe Firmware Download command
  * @fd:		File descriptor of nvme device
+ * @result:	The command completion result from CQE dword0
+ * @timeout:	Timeout in ms
  * @offset:	Offset in the firmware data
- * @data_len:	Length of data in this command in bytes
  * @data:	Userspace address of the firmware data
- * @timeout:	Timeout in ms
- * @result:	The command completion result from CQE dword0
+ * @data_len:	Length of data in this command in bytes
  */
 struct nvme_fw_download_args {
 	int args_size;
 	int fd;
+	__u32 *result;
+	__u32 timeout;
 	__u32 offset;
-	__u32 data_len;
 	void *data;
-	__u32 timeout;
-	__u32 *result;
-};
+	__u32 data_len;
+} __attribute__((packed, aligned(__alignof__(__u32*))));
 
 /**
  * nvme_fw_download() - Download part or all of a firmware image to the