ioctl: Rearrange members in nvme_resv_register_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_resv_register_args {
        int                        args_size;            /*     0     4 */
        int                        fd;                   /*     4     4 */
        __u32 *                    result;               /*     8     8 */
        __u32                      timeout;              /*    16     4 */
        __u32                      nsid;                 /*    20     4 */
        enum nvme_resv_rrega       rrega;                /*    24     4 */
        enum nvme_resv_cptpl       cptpl;                /*    28     4 */
        __u64                      crkey;                /*    32     8 */
        __u64                      nrkey;                /*    40     8 */
        _Bool                      iekey;                /*    48     1 */

        /* size: 56, cachelines: 1, members: 10 */
        /* padding: 7 */
        /* last cacheline: 56 bytes */
} __attribute__((__aligned__(8)));

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

Author: dwsuse

src/nvme/ioctl.h

@@ -3847,15 +3847,15 @@ int nvme_resv_acquire(struct nvme_resv_acquire_args *args);
 struct nvme_resv_register_args {
 	int args_size;
 	int fd;
+	__u32 *result;
+	__u32 timeout;
 	__u32 nsid;
 	enum nvme_resv_rrega rrega;
 	enum nvme_resv_cptpl cptpl;
-	bool iekey;
 	__u64 crkey;
 	__u64 nrkey;
-	__u32 timeout;
-	__u32 *result;
-};
+	bool iekey;
+} __attribute__((packed, aligned(__alignof__(__u64))));
 
 /**
  * nvme_resv_register() - Send an nvme reservation register