From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1426035AbcBRJzY (ORCPT ); Thu, 18 Feb 2016 04:55:24 -0500 Received: from mx2.suse.de ([195.135.220.15]:47759 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1425811AbcBRJzQ (ORCPT ); Thu, 18 Feb 2016 04:55:16 -0500 Date: Thu, 18 Feb 2016 10:55:38 +0100 From: Jan Kara To: Tejun Heo Cc: Tahsin Erdogan , Jan Kara , Jens Axboe , cgroups@vger.kernel.org, "Theodore Ts'o" , Nauman Rafique , linux-kernel@vger.kernel.org, Jan Kara Subject: Re: [PATCH block/for-4.5-fixes] writeback: keep superblock pinned during cgroup writeback association switches Message-ID: <20160218095538.GA4338@quack.suse.cz> References: <20160215210047.GN3965@htj.duckdns.org> <20160216182457.GO3741@mtj.duckdns.org> <20160217205721.GE14140@quack.suse.cz> <20160217210744.GA6479@mtj.duckdns.org> <20160217223009.GN14140@quack.suse.cz> <20160217230231.GC6479@mtj.duckdns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160217230231.GC6479@mtj.duckdns.org> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 17-02-16 18:02:31, Tejun Heo wrote: > On Wed, Feb 17, 2016 at 02:41:25PM -0800, Tahsin Erdogan wrote: > > With this patch, I am starting to have issues running fsck immediately > > after umount. > > > > *** fsck.ext4 output *** > > fsck from util-linux-ng 2.17.2 > > e2fsck 1.42.12-gg3 (9-Sep-2014) > > Warning! /dev/sdb3 is in use. > > Pass 1: Checking inodes, blocks, and sizes > > Deleted inode 62346243 has zero dtime. Fix? no > > Yeah, that'd be one of the side effects. Will think more about it. > Jan, do you know why we have both s_active and the rwsem at this > point? I can't tell why both are needed. I'm not sure I understand the question. Do you mean why both s_active and s_umount rwsem exist? s_active is a reference count keeping superblock alive - e.g. if the filesystem is mounted in more places, we need a reference for each mountpoint. s_umount is used when we want to block any umount operation until we are done. For example sync(2) is using it to make sure superblock doesn't disappear and so that we don't keep superblock alive after admin called umount(2). Honza -- Jan Kara SUSE Labs, CR