From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B4979C433DB for ; Wed, 24 Feb 2021 20:52:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 61B4D60202 for ; Wed, 24 Feb 2021 20:52:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234883AbhBXUwT (ORCPT ); Wed, 24 Feb 2021 15:52:19 -0500 Received: from mail.kernel.org ([198.145.29.99]:42880 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229598AbhBXUwT (ORCPT ); Wed, 24 Feb 2021 15:52:19 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 4AFA860202; Wed, 24 Feb 2021 20:51:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1614199898; bh=UVu8j9HBiMigfcshhTmAIfKTnpNaNe4tF+HqCtXt3Rc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=TuCzT09r0/WmdzOKO9/n+FHDYoPIG7is6vivKYZLViMcPJ6v4i8KouWJv+rD5pZog AbDz3VlgJuIyl9cZKa4yYi4pUrWidVXWTt/hlEduzQwOR71QDvYA7EZKwFOjNLSuop NKEUzrnFLg+xd9nAGfxiWsEOlkuCsyaRlLjKQ278ICQbvtOWEkRfitvRMay6JuVl9F SoVoqmr5q35Ob/sWTqEMMZnX/LxXGS5TOVwI1eDR5dLzq7N5Sg02zAaR5OD6LqJveS o06l9gmQtzcPgcqnq03nFtXGX8gDbgeI51klvVMqiXBwrqqOxM/s0P7tU7l/CSXZXo eTP3nGFNMR30Q== Date: Wed, 24 Feb 2021 12:51:37 -0800 From: "Darrick J. Wong" To: Dave Chinner Cc: linux-xfs@vger.kernel.org Subject: Re: [PATCH 4/8] xfs: async blkdev cache flush Message-ID: <20210224205137.GT7272@magnolia> References: <20210223033442.3267258-1-david@fromorbit.com> <20210223033442.3267258-5-david@fromorbit.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210223033442.3267258-5-david@fromorbit.com> Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Tue, Feb 23, 2021 at 02:34:38PM +1100, Dave Chinner wrote: > From: Dave Chinner > > The new checkpoint caceh flush mechanism requires us to issue an > unconditional cache flush before we start a new checkpoint. We don't > want to block for this if we can help it, and we have a fair chunk > of CPU work to do between starting the checkpoint and issuing the > first journal IO. > > Hence it makes sense to amortise the latency cost of the cache flush > by issuing it asynchronously and then waiting for it only when we > need to issue the first IO in the transaction. > > TO do this, we need async cache flush primitives to submit the cache > flush bio and to wait on it. THe block layer has no such primitives > for filesystems, so roll our own for the moment. > > Signed-off-by: Dave Chinner > --- > fs/xfs/xfs_bio_io.c | 30 ++++++++++++++++++++++++++++++ > fs/xfs/xfs_linux.h | 1 + > 2 files changed, 31 insertions(+) > > diff --git a/fs/xfs/xfs_bio_io.c b/fs/xfs/xfs_bio_io.c > index 5abf653a45d4..d55420bc72b5 100644 > --- a/fs/xfs/xfs_bio_io.c > +++ b/fs/xfs/xfs_bio_io.c > @@ -67,3 +67,33 @@ xfs_flush_bdev( > blkdev_issue_flush(bdev, GFP_NOFS); > } > > +void > +xfs_flush_bdev_async_endio( > + struct bio *bio) > +{ > + if (bio->bi_private) > + complete(bio->bi_private); > + bio_put(bio); > +} > + > +/* > + * Submit a request for an async cache flush to run. If the caller needs to wait > + * for the flush completion at a later point in time, they must supply a > + * valid completion. This will be signalled when the flush completes. > + * The caller never sees the bio that is issued here. > + */ > +void > +xfs_flush_bdev_async( > + struct block_device *bdev, Not sure why this isn't a buftarg function, since (AFAICT) this is the only caller in the ~30 patches you've sent to the list. Is there something else coming down the pipeline such that you only have a raw block_device pointer? > + struct completion *done) > +{ > + struct bio *bio; > + > + bio = bio_alloc(GFP_NOFS, 0); > + bio_set_dev(bio, bdev); > + bio->bi_opf = REQ_OP_WRITE | REQ_PREFLUSH | REQ_SYNC; > + bio->bi_private = done; > + bio->bi_end_io = xfs_flush_bdev_async_endio; Weird indent here. --D > + > + submit_bio(bio); > +} > diff --git a/fs/xfs/xfs_linux.h b/fs/xfs/xfs_linux.h > index e94a2aeefee8..293ff2355e80 100644 > --- a/fs/xfs/xfs_linux.h > +++ b/fs/xfs/xfs_linux.h > @@ -197,6 +197,7 @@ static inline uint64_t howmany_64(uint64_t x, uint32_t y) > int xfs_rw_bdev(struct block_device *bdev, sector_t sector, unsigned int count, > char *data, unsigned int op); > void xfs_flush_bdev(struct block_device *bdev); > +void xfs_flush_bdev_async(struct block_device *bdev, struct completion *done); > > #define ASSERT_ALWAYS(expr) \ > (likely(expr) ? (void)0 : assfail(NULL, #expr, __FILE__, __LINE__)) > -- > 2.28.0 >