* Fixed the strange vm_cache_ref reference count mechanism: now, a fresh

vm_cache_ref starts with a reference count of 1. When acquiring a vm_cache,
  you no longer need to worry if that should go through the vm_store, or not;
  as it now always does.
* map_backing_store() no longer needs to play with the vm_cache_ref
  references.
* that simplified some code.
* vfs_get_vnode_cache() now grabs a reference to the cache, if successful.
* better balanced vnode ownership on vnode_store creation (vnode_store
  released the vnode before if its creation failed).


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@15641 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/system/kernel/cache/file_cache.cpp

@@ -947,6 +947,7 @@ cache_prefetch_vnode(void *vnode, off_t offset, size_t size)
 
 out:
 	mutex_unlock(&cache->lock);
+	vm_cache_release_ref(cache);
 }