From: "Darrick J. Wong" Subject: Re: [PATCH 4/4] block: Optionally snapshot page contents to provide stable pages during write Date: Mon, 17 Dec 2012 14:56:17 -0800 Message-ID: <20121217225617.GB10874@blackbox.djwong.org> References: <20121213080740.23360.16346.stgit@blackbox.djwong.org> <20121213080811.23360.98131.stgit@blackbox.djwong.org> <20121216161336.GA6243@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: 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 Return-path: Received: from aserp1040.oracle.com ([141.146.126.69]:25711 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751077Ab2LQW5k (ORCPT ); Mon, 17 Dec 2012 17:57:40 -0500 Content-Disposition: inline In-Reply-To: <20121216161336.GA6243@gmail.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Mon, Dec 17, 2012 at 12:13:36AM +0800, Zheng Liu wrote: > 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_. Good catch! Thank you! --D > > 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 { > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html