rgw: fix BZ 1500904, Stale bucket index entry remains after object de…

…letion

We have a race condition:

 1. RGW client #1: requests an object be deleted.
 2. RGW client #1: sends a prepare op to bucket index OSD #1.
 3. OSD #1:        prepares the op, adding pending ops to the bucket dir entry
 4. RGW client #2: sends a list bucket to OSD #1
 5. RGW client #2: sees that there are pending operations on bucket
                   dir entry, and calls check_disk_state
 6. RGW client #2: check_disk_state sees that the object still exists, so it
                   sends CEPH_RGW_UPDATE to bucket index OSD (#1)
 7. RGW client #1: sends a delete object to object OSD (#2)
 8. OSD #2:        deletes the object
 9. RGW client #2: sends a complete op to bucket index OSD (#1)
10. OSD #1:        completes the op
11. OSD #1:        receives the CEPH_RGW_UPDATE and updates the bucket index
                   entry, thereby **RECREATING** it

Solution implemented:

At step #5 the object's dir entry exists. If we get to beginning of
step ceph#11 and the object's dir entry no longer exists, we know that the
dir entry was just actively being modified, and ignore the
CEPH_RGW_UPDATE operation, thereby NOT recreating it.

Signed-off-by: J. Eric Ivancich <[email protected]>
(cherry picked from commit b33f529)

src/cls/rgw/cls_rgw.cc

@@ -1865,7 +1865,8 @@ static int rgw_bucket_clear_olh(cls_method_context_t hctx, bufferlist *in, buffe
   return 0;
 }
 
-int rgw_dir_suggest_changes(cls_method_context_t hctx, bufferlist *in, bufferlist *out)
+int rgw_dir_suggest_changes(cls_method_context_t hctx,
+			    bufferlist *in, bufferlist *out)
 {
   CLS_LOG(1, "rgw_dir_suggest_changes()");
 
@@ -1958,8 +1959,21 @@ int rgw_dir_suggest_changes(cls_method_context_t hctx, bufferlist *in, bufferlis
         }
         break;
       case CEPH_RGW_UPDATE:
+	if (!cur_disk.exists) {
+	  // this update would only have been sent by the rgw client
+	  // if the rgw_bucket_dir_entry existed, however between that
+	  // check and now the entry has diappeared, so we were likely
+	  // in the midst of a delete op, and we will not recreate the
+	  // entry
+	  CLS_LOG(10,
+		  "CEPH_RGW_UPDATE not applied because rgw_bucket_dir_entry"
+		  " no longer exists\n");
+	  break;
+	}
+
         CLS_LOG(10, "CEPH_RGW_UPDATE name=%s instance=%s total_entries: %" PRId64 " -> %" PRId64 "\n",
                 cur_change.key.name.c_str(), cur_change.key.instance.c_str(), stats.num_entries, stats.num_entries + 1);
+
         stats.num_entries++;
         stats.total_size += cur_change.meta.accounted_size;
         stats.total_size_rounded += cls_rgw_get_rounded_size(cur_change.meta.accounted_size);
@@ -1980,10 +1994,9 @@ int rgw_dir_suggest_changes(cls_method_context_t hctx, bufferlist *in, bufferlis
           }
         }
         break;
-      }
-    }
-
-  }
+      } // switch(op)
+    } // if (cur_disk.pending_map.empty())
+  } // while (!in_iter.end())
 
   if (header_changed) {
     return write_bucket_header(hctx, &header);

src/rgw/rgw_rados.cc

@@ -8902,7 +8902,6 @@ int RGWRados::Object::Delete::delete_obj()
   index_op.set_zones_trace(params.zones_trace);
   index_op.set_bilog_flags(params.bilog_flags);
 
-
   r = index_op.prepare(CLS_RGW_OP_DEL, &state->write_tag);
   if (r < 0)
     return r;
@@ -12827,8 +12826,11 @@ int RGWRados::cls_bucket_list(RGWBucketInfo& bucket_info, int shard_id, rgw_obj_
     const string& name = vcurrents[pos]->first;
     struct rgw_bucket_dir_entry& dirent = vcurrents[pos]->second;
 
-    bool force_check = force_check_filter && force_check_filter(dirent.key.name);
-    if ((!dirent.exists && !dirent.is_delete_marker()) || !dirent.pending_map.empty() || force_check) {
+    bool force_check = force_check_filter &&
+        force_check_filter(dirent.key.name);
+    if ((!dirent.exists && !dirent.is_delete_marker()) ||
+        !dirent.pending_map.empty() ||
+        force_check) {
       /* there are uncommitted ops. We need to check the current state,
        * and if the tags are old we need to do cleanup as well. */
       librados::IoCtx sub_ctx;