+ * If we have a 32-bit userspace and 64-bit kernel, then the UAPI
+ * structures are incorrect, as the timespec structure from userspace
+ * is 4 bytes too small. We define these alternatives here for backward
+ * compatibility, the kernel understands both values.
+ */
+
+/*
+ * Structure size is different on 32bit and 64bit, has some padding if the
+ * structure is embedded. Packing makes sure the size is same on both, but will
+ * be misaligned on 64bit.
+ *
+ * NOTE: do not use in your code, this is for testing only
+ */
+struct btrfs_ioctl_timespec_32 {
+ __u64 sec;
+ __u32 nsec;
+} __attribute__ ((__packed__));
+
+struct btrfs_ioctl_received_subvol_args_32 {
+ char uuid[BTRFS_UUID_SIZE]; /* in */
+ __u64 stransid; /* in */
+ __u64 rtransid; /* out */
+ struct btrfs_ioctl_timespec_32 stime; /* in */
+ struct btrfs_ioctl_timespec_32 rtime; /* out */
+ __u64 flags; /* in */
+ __u64 reserved[16]; /* in */
+} __attribute__ ((__packed__));
+BUILD_ASSERT(sizeof(struct btrfs_ioctl_received_subvol_args_32) == 192);
+
+#define BTRFS_IOC_SET_RECEIVED_SUBVOL_32_COMPAT_DEFINED 1
+
+/*