Revert "librbd: remove limit on number of objects in the cache"

This reverts commit 367cf1bbf86233eb20ff2304e7d6caab77b84fcc.

Removing the limit on objects means we leak memory, since Objects without
any buffers can exist in the cache.

diff --git a/src/librbd/ImageCtx.cc b/src/librbd/ImageCtx.cc
index 77cb8503ad63f807bb875cd6b658692249eb7853..41518b67698cdec5a750141703d574a523686e7d 100644 (file)
--- a/src/librbd/ImageCtx.cc
+++ b/src/librbd/ImageCtx.cc
@@ -86,7 +86,7 @@ namespace librbd {
       object_cacher = new ObjectCacher(cct, pname, *writeback_handler, cache_lock,
                                       NULL, NULL,
                                       cct->_conf->rbd_cache_size,
-                                      (uint64_t) -1, // unlimited number of objects
+                                      10,  /* reset this in init */
                                       init_max_dirty,
                                       cct->_conf->rbd_cache_target_dirty,
                                       cct->_conf->rbd_cache_max_dirty_age,
@@ -182,6 +182,14 @@ namespace librbd {
       snprintf(format_string, len, "%s.%%016llx", object_prefix.c_str());
     }
 
+    // size object cache appropriately
+    if (object_cacher) {
+      uint64_t obj = cct->_conf->rbd_cache_size / (1ull << order);
+      ldout(cct, 10) << " cache bytes " << cct->_conf->rbd_cache_size << " order " << (int)order
+                    << " -> about " << obj << " objects" << dendl;
+      object_cacher->set_max_objects(obj * 4 + 10);
+    }
+
     ldout(cct, 10) << "init_layout stripe_unit " << stripe_unit
                   << " stripe_count " << stripe_count
                   << " object_size " << layout.fl_object_size