rbd: add img_obj_request_simple() helper

To clarify the conditions and make it easier to add new ones.

Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com>

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index eea44ce..6dae658 100644 (file)
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -2743,11 +2743,10 @@ out:
        return ret;
 }
 
-static int rbd_img_obj_request_submit(struct rbd_obj_request *obj_request)
+static bool img_obj_request_simple(struct rbd_obj_request *obj_request)
 {
        struct rbd_img_request *img_request;
        struct rbd_device *rbd_dev;
-       bool known;
 
        rbd_assert(obj_request_img_data_test(obj_request));
 
@@ -2755,22 +2754,35 @@ static int rbd_img_obj_request_submit(struct rbd_obj_request *obj_request)
        rbd_assert(img_request);
        rbd_dev = img_request->rbd_dev;
 
+       /* Reads */
+       if (!img_request_write_test(img_request))
+               return true;
+
+       /* Non-layered writes */
+       if (!img_request_layered_test(img_request))
+               return true;
+
        /*
-        * Only writes to layered images need special handling.
-        * Reads and non-layered writes are simple object requests.
-        * Layered writes that start beyond the end of the overlap
-        * with the parent have no parent data, so they too are
-        * simple object requests.  Finally, if the target object is
-        * known to already exist, its parent data has already been
-        * copied, so a write to the object can also be handled as a
-        * simple object request.
+        * Layered writes outside of the parent overlap range don't
+        * share any data with the parent.
         */
-       if (!img_request_write_test(img_request) ||
-               !img_request_layered_test(img_request) ||
-               !obj_request_overlaps_parent(obj_request) ||
-               ((known = obj_request_known_test(obj_request)) &&
-                       obj_request_exists_test(obj_request))) {
+       if (!obj_request_overlaps_parent(obj_request))
+               return true;
 
+       /*
+        * If the object is known to already exist, its parent data has
+        * already been copied.
+        */
+       if (obj_request_known_test(obj_request) &&
+           obj_request_exists_test(obj_request))
+               return true;
+
+       return false;
+}
+
+static int rbd_img_obj_request_submit(struct rbd_obj_request *obj_request)
+{
+       if (img_obj_request_simple(obj_request)) {
                struct rbd_device *rbd_dev;
                struct ceph_osd_client *osdc;
 
@@ -2786,7 +2798,7 @@ static int rbd_img_obj_request_submit(struct rbd_obj_request *obj_request)
         * start by reading the data for the full target object from
         * the parent so we can use it for a copyup to the target.
         */
-       if (known)
+       if (obj_request_known_test(obj_request))
                return rbd_img_obj_parent_read_full(obj_request);
 
        /* We don't know whether the target exists.  Go find out. */