librbd: request exclusive lock when moving to trash

Even if the image is in-use, moving it to the trash does not
remove any data. This also solves a race between snapshot-based
mirroring shutting down and being able to move a mirrored image
to the trash.

Signed-off-by: Jason Dillaman <dillaman@redhat.com>

src/librbd/api/Trash.cc

@@ -158,7 +158,7 @@ int Trash<I>::move(librados::IoCtx &io_ctx, rbd_trash_image_source_t source,
       ictx->exclusive_lock->block_requests(0);
 
       r = ictx->operations->prepare_image_update(
-        exclusive_lock::OPERATION_REQUEST_TYPE_GENERAL, false);
+        exclusive_lock::OPERATION_REQUEST_TYPE_GENERAL, true);
       if (r < 0) {
         lderr(cct) << "cannot obtain exclusive lock - not removing" << dendl;
         ictx->owner_lock.unlock_shared();