rbd: re-submit flattened write request (part 2)

Add code to rbd_img_obj_exists_callback() to detect when a clone's
parent image has disappeared, and re-submit the original write
request in that case.

Kill off some redundant assertions.

This completes the resolution for:
    http://tracker.ceph.com/issues/3763

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

1 files changed, 16 insertions, 2 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 5c2731859e8a..6b872f219774 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -2516,6 +2516,7 @@ out_err:
 static void rbd_img_obj_exists_callback(struct rbd_obj_request *obj_request)
 {
         struct rbd_obj_request *orig_request;
+        struct rbd_device *rbd_dev;
         int result;
 
         rbd_assert(!obj_request_img_data_test(obj_request));
@@ -2538,8 +2539,21 @@ static void rbd_img_obj_exists_callback(struct rbd_obj_request *obj_request)
                 obj_request->xferred, obj_request->length);
         rbd_obj_request_put(obj_request);
 
-        rbd_assert(orig_request);
-        rbd_assert(orig_request->img_request);
+        /*
+         * If the overlap has become 0 (most likely because the
+         * image has been flattened) we need to free the pages
+         * and re-submit the original write request.
+         */
+        rbd_dev = orig_request->img_request->rbd_dev;
+        if (!rbd_dev->parent_overlap) {
+                struct ceph_osd_client *osdc;
+
+                rbd_obj_request_put(orig_request);
+                osdc = &rbd_dev->rbd_client->client->osdc;
+                result = rbd_obj_request_submit(osdc, orig_request);
+                if (!result)
+                        return;
+        }
 
         /*
          * Our only purpose here is to determine whether the object