Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756355AbbHZJA2 (ORCPT ); Wed, 26 Aug 2015 05:00:28 -0400 Received: from mx2.suse.de ([195.135.220.15]:53242 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751859AbbHZJAZ (ORCPT ); Wed, 26 Aug 2015 05:00:25 -0400 Date: Wed, 26 Aug 2015 11:00:19 +0200 From: Jan Kara To: Tejun Heo Cc: Jens Axboe , Jan Kara , Eryu Guan , xfs@oss.sgi.com, axboe@fb.com, Dave Chinner , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: Re: [PATCH v2 block/for-linus] writeback: sync_inodes_sb() must write out I_DIRTY_TIME inodes and always call wait_sb_inodes() Message-ID: <20150826090019.GA3871@quack.suse.cz> References: <20150812101204.GE17933@dhcp-13-216.nay.redhat.com> <20150813004435.GN3902@dastard> <20150813224415.GG4496@mtj.duckdns.org> <20150825181152.GA26785@mtj.duckdns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150825181152.GA26785@mtj.duckdns.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3609 Lines: 103 On Tue 25-08-15 14:11:52, Tejun Heo wrote: > e79729123f63 ("writeback: don't issue wb_writeback_work if clean") > updated writeback path to avoid kicking writeback work items if there > are no inodes to be written out; unfortunately, the avoidance logic > was too aggressive and broke sync_inodes_sb(). > > * sync_inodes_sb() must write out I_DIRTY_TIME inodes but I_DIRTY_TIME > inodes dont't contribute to bdi/wb_has_dirty_io() tests and were > being skipped over. > > * inodes are taken off wb->b_dirty/io/more_io lists after writeback > starts on them. sync_inodes_sb() skipping wait_sb_inodes() when > bdi_has_dirty_io() breaks it by making it return while writebacks > are in-flight. > > This patch fixes the breakages by > > * Removing bdi_has_dirty_io() shortcut from bdi_split_work_to_wbs(). > The callers are already testing the condition. > > * Removing bdi_has_dirty_io() shortcut from sync_inodes_sb() so that > it always calls into bdi_split_work_to_wbs() and wait_sb_inodes(). > > * Making bdi_split_work_to_wbs() consider the b_dirty_time list for > WB_SYNC_ALL writebacks. > > Kudos to Eryu, Dave and Jan for tracking down the issue. > > Signed-off-by: Tejun Heo > Fixes: e79729123f63 ("writeback: don't issue wb_writeback_work if clean") > Link: http://lkml.kernel.org/g/20150812101204.GE17933@dhcp-13-216.nay.redhat.com > Reported-and-bisected-by: Eryu Guan > Cc: Dave Chinner > Cc: Jan Kara > Cc: Ted Ts'o > --- > fs/fs-writeback.c | 22 +++++++++++++--------- > 1 file changed, 13 insertions(+), 9 deletions(-) The patch looks good. You can add: Reviewed-by: Jan Kara Honza > > --- a/fs/fs-writeback.c > +++ b/fs/fs-writeback.c > @@ -844,14 +844,15 @@ static void bdi_split_work_to_wbs(struct > struct wb_iter iter; > > might_sleep(); > - > - if (!bdi_has_dirty_io(bdi)) > - return; > restart: > rcu_read_lock(); > bdi_for_each_wb(wb, bdi, &iter, next_blkcg_id) { > - if (!wb_has_dirty_io(wb) || > - (skip_if_busy && writeback_in_progress(wb))) > + /* SYNC_ALL writes out I_DIRTY_TIME too */ > + if (!wb_has_dirty_io(wb) && > + (base_work->sync_mode == WB_SYNC_NONE || > + list_empty(&wb->b_dirty_time))) > + continue; > + if (skip_if_busy && writeback_in_progress(wb)) > continue; > > base_work->nr_pages = wb_split_bdi_pages(wb, nr_pages); > @@ -899,8 +900,7 @@ static void bdi_split_work_to_wbs(struct > { > might_sleep(); > > - if (bdi_has_dirty_io(bdi) && > - (!skip_if_busy || !writeback_in_progress(&bdi->wb))) { > + if (!skip_if_busy || !writeback_in_progress(&bdi->wb)) { > base_work->auto_free = 0; > base_work->single_wait = 0; > base_work->single_done = 0; > @@ -2275,8 +2275,12 @@ void sync_inodes_sb(struct super_block * > }; > struct backing_dev_info *bdi = sb->s_bdi; > > - /* Nothing to do? */ > - if (!bdi_has_dirty_io(bdi) || bdi == &noop_backing_dev_info) > + /* > + * Can't skip on !bdi_has_dirty() because we should wait for !dirty > + * inodes under writeback and I_DIRTY_TIME inodes ignored by > + * bdi_has_dirty() need to be written out too. > + */ > + if (bdi == &noop_backing_dev_info) > return; > WARN_ON(!rwsem_is_locked(&sb->s_umount)); > > -- Jan Kara SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/