librbd: correct basic object map errors during refresh

If the object map is corrupt on-disk or too small for the image,
correct these basic issues as soon as possible.  The object map
is still flagged as invalid, but there will be less required repair
work if future IO is able to properly update the object map.

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

diff --git a/src/librbd/ObjectMap.cc b/src/librbd/ObjectMap.cc
index d06ae877e5b0d445e3777266354f89b05a3641bb..243a61ea264d827a710866c2ba807dc92984646e 100644 (file)
--- a/src/librbd/ObjectMap.cc
+++ b/src/librbd/ObjectMap.cc
@@ -161,9 +161,28 @@ void ObjectMap::refresh(uint64_t snap_id)
   CephContext *cct = m_image_ctx.cct;
   ldout(cct, 10) << &m_image_ctx << " refreshing object map" << dendl;
 
+  uint64_t num_objs = Striper::get_num_objects(
+    m_image_ctx.layout, m_image_ctx.get_image_size(snap_id));
+
   std::string oid(object_map_name(m_image_ctx.id, snap_id));
   int r = cls_client::object_map_load(&m_image_ctx.md_ctx, oid,
                                       &m_object_map);
+  if (r == -EINVAL) {
+    // object map is corrupt on-disk -- clear it and properly size it
+    // so future IO can keep the object map in sync
+    invalidate(snap_id);
+
+    librados::ObjectWriteOperation op;
+    rados::cls::lock::assert_locked(&op, RBD_LOCK_NAME, LOCK_EXCLUSIVE, "", "");
+    op.truncate(0);
+    cls_client::object_map_resize(&op, num_objs, OBJECT_NONEXISTENT);
+
+    r = m_image_ctx.md_ctx.operate(oid, &op);
+    if (r == 0) {
+      m_object_map.clear();
+      resize(num_objs, OBJECT_NONEXISTENT);
+    }
+  }
   if (r < 0) {
     lderr(cct) << "error refreshing object map: " << cpp_strerror(r)
                << dendl;
@@ -175,12 +194,20 @@ void ObjectMap::refresh(uint64_t snap_id)
   ldout(cct, 20) << "refreshed object map: " << m_object_map.size()
                  << dendl;
 
-  uint64_t num_objs = Striper::get_num_objects(
-    m_image_ctx.layout, m_image_ctx.get_image_size(snap_id));
   if (m_object_map.size() < num_objs) {
     lderr(cct) << "object map smaller than current object count: "
                << m_object_map.size() << " != " << num_objs << dendl;
     invalidate(snap_id);
+
+    // correct the size issue so future IO can keep the object map in sync
+    librados::ObjectWriteOperation op;
+    rados::cls::lock::assert_locked(&op, RBD_LOCK_NAME, LOCK_EXCLUSIVE, "", "");
+    cls_client::object_map_resize(&op, num_objs, OBJECT_NONEXISTENT);
+
+    r = m_image_ctx.md_ctx.operate(oid, &op);
+    if (r == 0) {
+      resize(num_objs, OBJECT_NONEXISTENT);
+    }
   } else if (m_object_map.size() > num_objs) {
     // resize op might have been interrupted
     ldout(cct, 1) << "object map larger than current object count: "
@@ -347,6 +374,15 @@ void ObjectMap::invalidate(uint64_t snap_id) {
   }
 }
 
+void ObjectMap::resize(uint64_t num_objs, uint8_t defualt_state) {
+  size_t orig_object_map_size = m_object_map.size();
+  m_object_map.resize(num_objs);
+  for (uint64_t i = orig_object_map_size;
+       i < m_object_map.size(); ++i) {
+    m_object_map[i] = defualt_state;
+  }
+}
+
 bool ObjectMap::Request::should_complete(int r) {
   CephContext *cct = m_image_ctx.cct;
   ldout(cct, 20) << &m_image_ctx << " should_complete: r=" << r << dendl;
@@ -437,12 +473,7 @@ void ObjectMap::ResizeRequest::finish(ObjectMap *object_map) {
 
   ldout(cct, 5) << &m_image_ctx << " resizing in-memory object map: "
                << m_num_objs << dendl;
-  size_t orig_object_map_size = object_map->m_object_map.size();
-  object_map->m_object_map.resize(m_num_objs);
-  for (uint64_t i = orig_object_map_size;
-       i < object_map->m_object_map.size(); ++i) {
-    object_map->m_object_map[i] = m_default_object_state;
-  }
+  object_map->resize(m_num_objs, m_default_object_state);
 }
 
 void ObjectMap::UpdateRequest::send() {

diff --git a/src/librbd/ObjectMap.h b/src/librbd/ObjectMap.h
index b85f4e26f842450aa606ba91f12a6f1c739744bd..95bb85227585058733d96683e0658510f6117438 100644 (file)
--- a/src/librbd/ObjectMap.h
+++ b/src/librbd/ObjectMap.h
@@ -123,6 +123,7 @@ private:
   bool m_enabled;
 
   void invalidate(uint64_t snap_id);
+  void resize(uint64_t num_objs, uint8_t default_state);
 };
 
 } // namespace librbd