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=-3.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY autolearn=no 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 94D19C433DF for ; Tue, 18 Aug 2020 16:13:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 68CF8207DA for ; Tue, 18 Aug 2020 16:13:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="XedNvxk9" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726816AbgHRQNY (ORCPT ); Tue, 18 Aug 2020 12:13:24 -0400 Received: from userp2130.oracle.com ([156.151.31.86]:34578 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726633AbgHRQNV (ORCPT ); Tue, 18 Aug 2020 12:13:21 -0400 Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 07IGCR6b076721; Tue, 18 Aug 2020 16:12:35 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2020-01-29; bh=Z4JyWG9GYx40D449jT2SjIZ+/FrA45k/t7nbWC1W2ME=; b=XedNvxk9JX13hSSYLNXrWjhgbNP1hh4R07ULkgct1y9+gFtvsgtt4PSEEH2fcM9j3uvM F2CZgJvb50atFE53NE8F5K91J9zov24NAuLsixCcSG/eU/Kilo/87u/ttgicq2UBv054 +piXEOWrprHZler9cm0LBJUVBiL/tguVYpRmwq3jufop97+YSv75eIVYL309EPswKvrZ Mz0ew/U53+lZHRm1Bm2oeBFVZyxlIjuEncZ3gijk9AffvyZGb0Gtjt8DSeuO59MGkqbQ UQWjWzKK/NHj5kdXJ41j6TCUNw0LR2iwiWDYMT/4g2c52+sNz9dHbtpluYqIjNgJlbUM Bg== Received: from aserp3020.oracle.com (aserp3020.oracle.com [141.146.126.70]) by userp2130.oracle.com with ESMTP id 32x74r5vc8-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 18 Aug 2020 16:12:35 +0000 Received: from pps.filterd (aserp3020.oracle.com [127.0.0.1]) by aserp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 07IFllTW076145; Tue, 18 Aug 2020 16:12:34 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by aserp3020.oracle.com with ESMTP id 32xsm37mj4-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 18 Aug 2020 16:12:34 +0000 Received: from abhmp0018.oracle.com (abhmp0018.oracle.com [141.146.116.24]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 07IGCU8l025942; Tue, 18 Aug 2020 16:12:30 GMT Received: from localhost (/10.159.245.241) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 18 Aug 2020 09:12:30 -0700 Date: Tue, 18 Aug 2020 09:12:29 -0700 From: "Darrick J. Wong" To: Matthew Wilcox Cc: Yu Kuai , hch@infradead.org, david@fromorbit.com, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, yi.zhang@huawei.com Subject: Re: [RFC PATCH V2] iomap: add support to track dirty state of sub pages Message-ID: <20200818161229.GK6107@magnolia> References: <20200818134618.2345884-1-yukuai3@huawei.com> <20200818155305.GR17456@casper.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200818155305.GR17456@casper.infradead.org> X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9716 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 suspectscore=0 malwarescore=0 mlxscore=0 phishscore=0 spamscore=0 mlxlogscore=999 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2008180113 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9717 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 impostorscore=0 mlxlogscore=999 priorityscore=1501 phishscore=0 spamscore=0 mlxscore=0 adultscore=0 suspectscore=0 lowpriorityscore=0 bulkscore=0 malwarescore=0 clxscore=1011 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2008180114 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 18, 2020 at 04:53:05PM +0100, Matthew Wilcox wrote: > On Tue, Aug 18, 2020 at 09:46:18PM +0800, Yu Kuai wrote: > > changes from v1: > > - separate set dirty and clear dirty functions > > - don't test uptodate bit in iomap_writepage_map() > > - use one bitmap array for uptodate and dirty. > > This looks much better. > > > + spinlock_t state_lock; > > + /* > > + * The first half bits are used to track sub-page uptodate status, > > + * the second half bits are for dirty status. > > + */ > > + DECLARE_BITMAP(state, PAGE_SIZE / 256); > > It would be better to use the same wording as below: > > > + bitmap_zero(iop->state, PAGE_SIZE * 2 / SECTOR_SIZE); ISTR there was some reason why '512' was hardcoded in here instead of SECTOR_SIZE. I /think/ it was so that iomap.h did not then have a hard dependency on blkdev.h and everything else that requires... https://lore.kernel.org/linux-xfs/20181215105155.GD1575@lst.de/ --D > > [...] > > > +static void > > +iomap_iop_set_range_dirty(struct page *page, unsigned int off, > > + unsigned int len) > > +{ > > + struct iomap_page *iop = to_iomap_page(page); > > + struct inode *inode = page->mapping->host; > > + unsigned int total = PAGE_SIZE / SECTOR_SIZE; > > + unsigned int first = off >> inode->i_blkbits; > > + unsigned int last = (off + len - 1) >> inode->i_blkbits; > > + unsigned long flags; > > + unsigned int i; > > + > > + spin_lock_irqsave(&iop->state_lock, flags); > > + for (i = first; i <= last; i++) > > + set_bit(i + total, iop->state); > > + spin_unlock_irqrestore(&iop->state_lock, flags); > > +} > > How about: > > - unsigned int total = PAGE_SIZE / SECTOR_SIZE; > ... > + first += PAGE_SIZE / SECTOR_SIZE; > + last += PAGE_SIZE / SECTOR_SIZE; > ... > for (i = first; i <= last; i++) > - set_bit(i + total, iop->state); > + set_bit(i, iop->state); > > We might want > > #define DIRTY_BITS(x) ((x) + PAGE_SIZE / SECTOR_SIZE) > > and then we could do: > > + unsigned int last = DIRTY_BITS((off + len - 1) >> inode->i_blkbits); > > That might be overthinking things a bit though. > > > @@ -705,6 +767,7 @@ __iomap_write_end(struct inode *inode, loff_t pos, unsigned len, > > if (unlikely(copied < len && !PageUptodate(page))) > > return 0; > > iomap_set_range_uptodate(page, offset_in_page(pos), len); > > + iomap_set_range_dirty(page, offset_in_page(pos), len); > > iomap_set_page_dirty(page); > > I would move the call to iomap_set_page_dirty() into > iomap_set_range_dirty() to parallel iomap_set_range_uptodate more closely. > We don't want a future change to add a call to iomap_set_range_dirty() > and miss the call to iomap_set_page_dirty(). > > > return copied; > > } > > @@ -1030,6 +1093,7 @@ iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length, > > WARN_ON_ONCE(!PageUptodate(page)); > > iomap_page_create(inode, page); > > set_page_dirty(page); > > + iomap_set_range_dirty(page, offset_in_page(pos), length); > > I would move all this from the mkwrite_actor() to iomap_page_mkwrite() > and call it once with (0, PAGE_SIZE) rather than calling it once for > each extent in the page. > > > @@ -1435,6 +1500,8 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc, > > */ > > set_page_writeback_keepwrite(page); > > } else { > > + iomap_clear_range_dirty(page, 0, > > + end_offset - page_offset(page) + 1); > > clear_page_dirty_for_io(page); > > set_page_writeback(page); > > I'm not sure it's worth doing this calculation. Better to just clear > the dirty bits on the entire page? Opinions?