From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kara Subject: Re: [PATCH] writeback: Fix periodic writeback after fs mount Date: Thu, 27 Jun 2013 19:01:33 +0200 Message-ID: <20130627170133.GA28935@quack.suse.cz> References: <1369903459-10295-1-git-send-email-jack@suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Wu Fengguang , linux-fsdevel@vger.kernel.org, Bert De Jonghe , Jan Kara To: Jens Axboe Return-path: Received: from cantor2.suse.de ([195.135.220.15]:51449 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752018Ab3F0RBm (ORCPT ); Thu, 27 Jun 2013 13:01:42 -0400 Content-Disposition: inline In-Reply-To: <1369903459-10295-1-git-send-email-jack@suse.cz> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Thu 30-05-13 10:44:19, Jan Kara wrote: > Code in blkdev.c moves a device inode to default_backing_dev_info when > the last reference to the device is put and moves the device inode back > to its bdi when the first reference is acquired. This includes moving to > wb.b_dirty list if the device inode is dirty. The code however doesn't > setup timer to wake corresponding flusher thread and while wb.b_dirty > list is non-empty __mark_inode_dirty() will not set it up either. Thus > periodic writeback is effectively disabled until a sync(2) call which can > lead to unexpected data loss in case of crash or power failure. > > Fix the problem by setting up a timer for periodic writeback in case we > add the first dirty inode to wb.b_dirty list in bdev_inode_switch_bdi(). > > Reported-by: Bert De Jonghe > CC: stable@vger.kernel.org # >= 3.0 > Signed-off-by: Jan Kara Jens, I'm going over my submitted patches and I don't think you've merged this patch. Did you? Honza > --- > fs/block_dev.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/fs/block_dev.c b/fs/block_dev.c > index 2091db8..85f5c85 100644 > --- a/fs/block_dev.c > +++ b/fs/block_dev.c > @@ -58,17 +58,24 @@ static void bdev_inode_switch_bdi(struct inode *inode, > struct backing_dev_info *dst) > { > struct backing_dev_info *old = inode->i_data.backing_dev_info; > + bool wakeup_bdi = false; > > if (unlikely(dst == old)) /* deadlock avoidance */ > return; > bdi_lock_two(&old->wb, &dst->wb); > spin_lock(&inode->i_lock); > inode->i_data.backing_dev_info = dst; > - if (inode->i_state & I_DIRTY) > + if (inode->i_state & I_DIRTY) { > + if (bdi_cap_writeback_dirty(dst) && !wb_has_dirty_io(&dst->wb)) > + wakeup_bdi = true; > list_move(&inode->i_wb_list, &dst->wb.b_dirty); > + } > spin_unlock(&inode->i_lock); > spin_unlock(&old->wb.list_lock); > spin_unlock(&dst->wb.list_lock); > + > + if (wakeup_bdi) > + bdi_wakeup_thread_delayed(dst); > } > > /* Kill _all_ buffers and pagecache , dirty or not.. */ > -- > 1.8.1.4 > -- Jan Kara SUSE Labs, CR