From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753989AbZIKHrW (ORCPT ); Fri, 11 Sep 2009 03:47:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753471AbZIKHrV (ORCPT ); Fri, 11 Sep 2009 03:47:21 -0400 Received: from brick.kernel.dk ([93.163.65.50]:45125 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753053AbZIKHrV (ORCPT ); Fri, 11 Sep 2009 03:47:21 -0400 Date: Fri, 11 Sep 2009 09:47:23 +0200 From: Jens Axboe To: Christoph Hellwig Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, chris.mason@oracle.com, david@fromorbit.com, tytso@mit.edu, akpm@linux-foundation.org, jack@suse.cz Subject: Re: [PATCH 2/8] writeback: move dirty inodes from super_block to backing_dev_info Message-ID: <20090911074723.GF18599@kernel.dk> References: <1251880967-1136-1-git-send-email-jens.axboe@oracle.com> <1251880967-1136-3-git-send-email-jens.axboe@oracle.com> <20090904025609.GC3658@infradead.org> <20090904065357.GP18599@kernel.dk> <20090904154305.GA10002@infradead.org> <20090906184358.GM18599@kernel.dk> <20090908184442.GB5956@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090908184442.GB5956@infradead.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 08 2009, Christoph Hellwig wrote: > On Sun, Sep 06, 2009 at 08:43:59PM +0200, Jens Axboe wrote: > > On Fri, Sep 04 2009, Christoph Hellwig wrote: > > > On Fri, Sep 04, 2009 at 08:53:57AM +0200, Jens Axboe wrote: > > > > > + if (wbc->sync_mode == WB_SYNC_ALL) > > > > > + bdi_wait_on_work_clear(&work); > > > > > } > > > > > > > > That doesn't work, you have to wait for on-stack work. So either we just > > > > punt and not do anything for WB_SYNC_NONE if the allocation fails, or we > > > > punt to stack and do the wait. Since it's a cleaning action and > > > > allocation fails, falling back to the stack and waiting seems like the > > > > most appropriate choice. > > > > > > True, the wait needs to be unconditional. Updated version below. > > > > (did you forget that patch? it's not there). > > Here we go, sorry: I have applied this to a postmerge writeback branch. I made one change, though: > + if (wbc->sync_mode != WB_SYNC_ALL) { > + struct bdi_work *w = bdi_alloc_work(wbc); > + if (w) { > + bdi_queue_work(wbc->bdi, w); > + return; > + } We should make that bdi_queue_work() unconditional, if you want to make sure that we current thread wakes up and actually flushes some old data when allocation fails. void bdi_start_writeback(struct writeback_control *wbc) { /* * WB_SYNC_NONE is opportunistic writeback. If this allocation fails, * bdi_queue_work() will wake up the thread and flush old data. This * should ensure some amount of progress in freeing memory. */ if (wbc->sync_mode != WB_SYNC_ALL) { struct bdi_work *w = bdi_alloc_work(wbc); bdi_queue_work(wbc->bdi, w); } else { struct bdi_work work; bdi_work_init(&work, wbc); work.state |= WS_ONSTACK; bdi_queue_work(wbc->bdi, &work); bdi_wait_on_work_clear(&work); } } -- Jens Axboe