rbd: add an object request flag for image data objects

Add a flag to distinguish between object requests being done on
standalone objects and requests being sent for objects representing
rbd image data (i.e., object requests that are the result of image
request).
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

drivers/block/rbd.c

@@ -172,6 +172,7 @@ enum obj_request_type {
 
 enum obj_req_flags {
 	OBJ_REQ_DONE,		/* completion flag: not done = 0, done = 1 */
+	OBJ_REQ_IMG_DATA,	/* object usage: standalone = 0, image = 1 */
 };
 
 struct rbd_obj_request {
@@ -1099,6 +1100,24 @@ static bool obj_request_done_test(struct rbd_obj_request *obj_request)
 	return test_bit(OBJ_REQ_DONE, &obj_request->flags) != 0;
 }
 
+static void obj_request_img_data_set(struct rbd_obj_request *obj_request)
+{
+	if (test_and_set_bit(OBJ_REQ_IMG_DATA, &obj_request->flags)) {
+		struct rbd_img_request *img_request = obj_request->img_request;
+		struct rbd_device *rbd_dev;
+
+		rbd_dev = img_request ? img_request->rbd_dev : NULL;
+		rbd_warn(rbd_dev, "obj_request %p already marked img_data\n",
+			obj_request);
+	}
+}
+
+static bool obj_request_img_data_test(struct rbd_obj_request *obj_request)
+{
+	smp_mb();
+	return test_bit(OBJ_REQ_IMG_DATA, &obj_request->flags) != 0;
+}
+
 static void rbd_obj_request_get(struct rbd_obj_request *obj_request)
 {
 	dout("%s: obj %p (was %d)\n", __func__, obj_request,
@@ -1139,6 +1158,8 @@ static inline void rbd_img_obj_request_add(struct rbd_img_request *img_request,
 	rbd_obj_request_get(obj_request);
 	obj_request->img_request = img_request;
 	obj_request->which = img_request->obj_request_count;
+	rbd_assert(!obj_request_img_data_test(obj_request));
+	obj_request_img_data_set(obj_request);
 	rbd_assert(obj_request->which != BAD_WHICH);
 	img_request->obj_request_count++;
 	list_add_tail(&obj_request->links, &img_request->obj_requests);
@@ -1158,6 +1179,7 @@ static inline void rbd_img_obj_request_del(struct rbd_img_request *img_request,
 	img_request->obj_request_count--;
 	rbd_assert(obj_request->which == img_request->obj_request_count);
 	obj_request->which = BAD_WHICH;
+	rbd_assert(obj_request_img_data_test(obj_request));
 	rbd_assert(obj_request->img_request == img_request);
 	obj_request->img_request = NULL;
 	obj_request->callback = NULL;
@@ -1343,7 +1365,9 @@ static void rbd_osd_req_callback(struct ceph_osd_request *osd_req,
 
 	dout("%s: osd_req %p msg %p\n", __func__, osd_req, msg);
 	rbd_assert(osd_req == obj_request->osd_req);
-	rbd_assert(!!obj_request->img_request ^
+	rbd_assert(obj_request_img_data_test(obj_request) ^
+				!obj_request->img_request);
+	rbd_assert(obj_request_img_data_test(obj_request) ^
 				(obj_request->which == BAD_WHICH));
 
 	if (osd_req->r_result < 0)
@@ -1413,12 +1437,13 @@ static struct ceph_osd_request *rbd_osd_req_create(
 					bool write_request,
 					struct rbd_obj_request *obj_request)
 {
-	struct rbd_img_request *img_request = obj_request->img_request;
 	struct ceph_snap_context *snapc = NULL;
 	struct ceph_osd_client *osdc;
 	struct ceph_osd_request *osd_req;
 
-	if (img_request) {
+	if (obj_request_img_data_test(obj_request)) {
+		struct rbd_img_request *img_request = obj_request->img_request;
+
 		rbd_assert(write_request ==
 				img_request_write_test(img_request));
 		if (write_request)
@@ -1605,10 +1630,13 @@ static void rbd_img_request_destroy(struct kref *kref)
 
 static bool rbd_img_obj_end_request(struct rbd_obj_request *obj_request)
 {
-	struct rbd_img_request *img_request = obj_request->img_request;
+	struct rbd_img_request *img_request;
 	unsigned int xferred;
 	int result;
 
+	rbd_assert(obj_request_img_data_test(obj_request));
+	img_request = obj_request->img_request;
+
 	rbd_assert(!img_request_child_test(img_request));
 	rbd_assert(img_request->rq != NULL);
 
@@ -1637,6 +1665,7 @@ static void rbd_img_obj_callback(struct rbd_obj_request *obj_request)
 	u32 which = obj_request->which;
 	bool more = true;
 
+	rbd_assert(obj_request_img_data_test(obj_request));
 	img_request = obj_request->img_request;
 
 	dout("%s: img %p obj %p\n", __func__, img_request, obj_request);