ceph: drop unconnected inodes

Positve dentry and corresponding inode are always accompanied in MDS reply.
So no need to keep inode in the cache after dropping all its aliases.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Sage Weil <sage@inktank.com>

fs/ceph/inode.c

@@ -436,6 +436,16 @@ void ceph_destroy_inode(struct inode *inode)
 	call_rcu(&inode->i_rcu, ceph_i_callback);
 }
 
+int ceph_drop_inode(struct inode *inode)
+{
+	/*
+	 * Positve dentry and corresponding inode are always accompanied
+	 * in MDS reply. So no need to keep inode in the cache after
+	 * dropping all its aliases.
+	 */
+	return 1;
+}
+
 /*
  * Helpers to fill in size, ctime, mtime, and atime.  We have to be
  * careful because either the client or MDS may have more up to date