librbd: don't attempt to invalidate an object map in R/O mode

The ImageWatcher is not initialized when in R/O mode, which
resulted in a NULL pointer dereference.

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

diff --git a/src/librbd/ObjectMap.cc b/src/librbd/ObjectMap.cc
index d45bd65fe4e2f9f7b871fb83bf88868f966c57a7..db17daa577d71b19602a124715b62bf9e6fa7426 100644 (file)
--- a/src/librbd/ObjectMap.cc
+++ b/src/librbd/ObjectMap.cc
@@ -429,6 +429,7 @@ void ObjectMap::aio_resize(uint64_t new_size, uint8_t default_object_state,
                           Context *on_finish) {
   assert(m_image_ctx.test_features(RBD_FEATURE_OBJECT_MAP));
   assert(m_image_ctx.owner_lock.is_locked());
+  assert(m_image_ctx.image_watcher != NULL);
   assert(!m_image_ctx.image_watcher->is_lock_supported() ||
          m_image_ctx.image_watcher->is_lock_owner());
 
@@ -453,6 +454,7 @@ bool ObjectMap::aio_update(uint64_t start_object_no, uint64_t end_object_no,
   assert(m_image_ctx.snap_lock.is_locked());
   assert((m_image_ctx.features & RBD_FEATURE_OBJECT_MAP) != 0);
   assert(m_image_ctx.owner_lock.is_locked());
+  assert(m_image_ctx.image_watcher != NULL);
   assert(!m_image_ctx.image_watcher->is_lock_supported(m_image_ctx.snap_lock) ||
          m_image_ctx.image_watcher->is_lock_owner());
   assert(m_image_ctx.object_map_lock.is_wlocked());
@@ -518,8 +520,9 @@ void ObjectMap::invalidate(uint64_t snap_id) {
   }
 
   // do not update on-disk flags if not image owner
-  if (m_image_ctx.image_watcher->is_lock_supported(m_image_ctx.snap_lock) &&
-      !m_image_ctx.image_watcher->is_lock_owner()) {
+  if (m_image_ctx.image_watcher == NULL ||
+      (m_image_ctx.image_watcher->is_lock_supported(m_image_ctx.snap_lock) &&
+       !m_image_ctx.image_watcher->is_lock_owner())) {
     return;
   }