PM: hibernate: return -ENODATA if the snapshot image is not loaded

snapshot_image_loaded() is used in both the in-kernel and the
userspace restore path to ensure that the snapshot image has been
completely loaded. However the latter path returns -EPERM in such
situations, which is meant for cases where the operation is neither
write-only nor ready.

This patch updates the check so the returned error code is -ENODATA in
both cases.

Suggested-by: Brian Geffon <bgeffon@google.com>
Signed-off-by: Alberto Garcia <berto@igalia.com>
Acked-by: Brian Geffon <bgeffon@google.com>
Link: https://patch.msgid.link/8cfda38659c623f5392f3458cb32504ffd556a74.1773075892.git.berto@igalia.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: bertogg

kernel/power/user.c

@@ -322,11 +322,14 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd,
 		error = snapshot_write_finalize(&data->handle);
 		if (error)
 			break;
-		if (data->mode != O_WRONLY || !data->frozen ||
-		    !snapshot_image_loaded(&data->handle)) {
+		if (data->mode != O_WRONLY || !data->frozen) {
 			error = -EPERM;
 			break;
 		}
+		if (!snapshot_image_loaded(&data->handle)) {
+			error = -ENODATA;
+			break;
+		}
 		error = hibernation_restore(data->platform_support);
 		break;