Return-Path: linux-nfs-owner@vger.kernel.org Received: from cantor2.suse.de ([195.135.220.15]:58454 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752406AbbANN7U (ORCPT ); Wed, 14 Jan 2015 08:59:20 -0500 Date: Wed, 14 Jan 2015 14:59:14 +0100 From: Jan Kara To: Christoph Hellwig Cc: Jens Axboe , David Howells , Tejun Heo , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-mtd@lists.infradead.org, linux-nfs@vger.kernel.org, ceph-devel@vger.kernel.org Subject: Re: [PATCH 11/12] fs: don't reassign dirty inodes to default_backing_dev_info Message-ID: <20150114135914.GL10215@quack.suse.cz> References: <1421228561-16857-1-git-send-email-hch@lst.de> <1421228561-16857-12-git-send-email-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1421228561-16857-12-git-send-email-hch@lst.de> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Wed 14-01-15 10:42:40, Christoph Hellwig wrote: > If we have dirty inodes we need to call the filesystem for it, even if the > device has been removed and the filesystem will error out early. The > current code does that by reassining all dirty inodes to the default > backing_dev_info when a bdi is unlinked, but that's pretty pointless given > that the bdi must always outlive the super block. > > Instead of stopping writeback at unregister time and moving inodes to the > default bdi just keep the current bdi alive until it is destroyed. The > containing objects of the bdi ensure this doesn't happen until all > writeback has finished by erroring out. > > Signed-off-by: Christoph Hellwig > Reviewed-by: Tejun Heo Looks good. You can add: Reviewed-by: Jan Kara One nit below: > --- > mm/backing-dev.c | 91 +++++++++++++++----------------------------------------- > 1 file changed, 24 insertions(+), 67 deletions(-) > > diff --git a/mm/backing-dev.c b/mm/backing-dev.c > index 52e0c76..3ebba25 100644 > --- a/mm/backing-dev.c > +++ b/mm/backing-dev.c ... > @@ -471,37 +445,20 @@ void bdi_destroy(struct backing_dev_info *bdi) > { > int i; > > - /* > - * Splice our entries to the default_backing_dev_info. This > - * condition shouldn't happen. @wb must be empty at this point and > - * dirty inodes on it might cause other issues. This workaround is > - * added by ce5f8e779519 ("writeback: splice dirty inode entries to > - * default bdi on bdi_destroy()") without root-causing the issue. > - * > - * http://lkml.kernel.org/g/1253038617-30204-11-git-send-email-jens.axboe@oracle.com > - * http://thread.gmane.org/gmane.linux.file-systems/35341/focus=35350 > - * > - * We should probably add WARN_ON() to find out whether it still > - * happens and track it down if so. > - */ > - if (bdi_has_dirty_io(bdi)) { > - struct bdi_writeback *dst = &default_backing_dev_info.wb; > - > - bdi_lock_two(&bdi->wb, dst); > - list_splice(&bdi->wb.b_dirty, &dst->b_dirty); > - list_splice(&bdi->wb.b_io, &dst->b_io); > - list_splice(&bdi->wb.b_more_io, &dst->b_more_io); > - spin_unlock(&bdi->wb.list_lock); > - spin_unlock(&dst->list_lock); > - } > - > - bdi_unregister(bdi); > + bdi_wb_shutdown(bdi); > > + WARN_ON(!list_empty(&bdi->work_list)); > + WARN_ON(delayed_work_pending(&bdi->wb.dwork)); > WARN_ON(delayed_work_pending(&bdi->wb.dwork)); You have the warning twice here... Honza -- Jan Kara SUSE Labs, CR