From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753354Ab2LPQA3 (ORCPT ); Sun, 16 Dec 2012 11:00:29 -0500 Received: from mail-pb0-f46.google.com ([209.85.160.46]:63727 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753120Ab2LPQAZ (ORCPT ); Sun, 16 Dec 2012 11:00:25 -0500 Date: Mon, 17 Dec 2012 00:13:36 +0800 From: Zheng Liu To: "Darrick J. Wong" Cc: axboe@kernel.dk, lucho@ionkov.net, jack@suse.cz, ericvh@gmail.com, viro@zeniv.linux.org.uk, rminnich@sandia.gov, tytso@mit.edu, martin.petersen@oracle.com, neilb@suse.de, david@fromorbit.com, linux-kernel@vger.kernel.org, hch@infradead.org, linux-fsdevel@vger.kernel.org, adilger.kernel@dilger.ca, bharrosh@panasas.com, jlayton@samba.org, v9fs-developer@lists.sourceforge.net, linux-ext4@vger.kernel.org Subject: Re: [PATCH 4/4] block: Optionally snapshot page contents to provide stable pages during write Message-ID: <20121216161336.GA6243@gmail.com> Mail-Followup-To: "Darrick J. Wong" , axboe@kernel.dk, lucho@ionkov.net, jack@suse.cz, ericvh@gmail.com, viro@zeniv.linux.org.uk, rminnich@sandia.gov, tytso@mit.edu, martin.petersen@oracle.com, neilb@suse.de, david@fromorbit.com, linux-kernel@vger.kernel.org, hch@infradead.org, linux-fsdevel@vger.kernel.org, adilger.kernel@dilger.ca, bharrosh@panasas.com, jlayton@samba.org, v9fs-developer@lists.sourceforge.net, linux-ext4@vger.kernel.org References: <20121213080740.23360.16346.stgit@blackbox.djwong.org> <20121213080811.23360.98131.stgit@blackbox.djwong.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121213080811.23360.98131.stgit@blackbox.djwong.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 On Thu, Dec 13, 2012 at 12:08:11AM -0800, Darrick J. Wong wrote: > diff --git a/mm/bounce.c b/mm/bounce.c > index 0420867..fa11935 100644 > --- a/mm/bounce.c > +++ b/mm/bounce.c > @@ -178,6 +178,38 @@ static void bounce_end_io_read_isa(struct bio *bio, int err) > __bounce_end_io_read(bio, isa_page_pool, err); > } > > +#ifdef CONFIG_NEED_BOUNCE_POOL > +static int might_snapshot_stable_page_write(struct bio **bio_orig) > +{ > + return bio_data_dir(*bio_orig) == WRITE; > +} > + > +static int should_snapshot_stable_pages(struct page *page, int rw) > +{ > + struct backing_dev_info *bdi; > + struct address_space *mapping = page_mapping(page); > + > + if (!mapping) > + return 0; > + bdi = mapping->backing_dev_info; > + if (!bdi_cap_stable_pages_required(bdi)) > + return 0; > + > + return mapping->host->i_sb->s_flags & MS_SNAP_STABLE && > + rw == WRITE; > +} > +#else > +static int might_snapshot_stable_page_write(struct bio **bio_orig) > +{ > + return 0; > +} > + > +static int should_snapshot_static_pages(struct page *page, int rw) ^^^^^^ It should be _stable_. Regards, - Zheng > +{ > + return 0; > +} > +#endif /* CONFIG_NEED_BOUNCE_POOL */ > + > static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig, > mempool_t *pool) > { > @@ -192,7 +224,8 @@ static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig, > /* > * is destination page below bounce pfn? > */ > - if (page_to_pfn(page) <= queue_bounce_pfn(q)) > + if (page_to_pfn(page) <= queue_bounce_pfn(q) && > + !should_snapshot_stable_pages(page, rw)) > continue; > > /* > @@ -284,7 +317,8 @@ void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig) > * don't waste time iterating over bio segments > */ > if (!(q->bounce_gfp & GFP_DMA)) { > - if (queue_bounce_pfn(q) >= blk_max_pfn) > + if (queue_bounce_pfn(q) >= blk_max_pfn && > + !might_snapshot_stable_page_write(bio_orig)) > return; > pool = page_pool; > } else {