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=-17.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 D16A4C4361B for ; Mon, 14 Dec 2020 09:57:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9A09D225AC for ; Mon, 14 Dec 2020 09:57:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388143AbgLNJ5w (ORCPT ); Mon, 14 Dec 2020 04:57:52 -0500 Received: from mx2.suse.de ([195.135.220.15]:39822 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727309AbgLNJ5v (ORCPT ); Mon, 14 Dec 2020 04:57:51 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1607939825; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=D4teTxRS+oV8JgpdVGINnlOveQi+6OupaUMXZMtbadY=; b=qnWpD+fI6K1W8Am8A6NQSGx9sWf93OvlVdGNYW9gef+vwF2VB3vAxTYGJmABAnefx39ghi GSj7OyiZRLB9+ayXvI5j6qc0H3wjqJHf40ycw0sWV4WdCszmWn7R/yDf2JRRT9uLQ0TF+C tO8kE/ECq3ltfNV0erEnesotYoCcAdg= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 1B8A3AC10; Mon, 14 Dec 2020 09:57:05 +0000 (UTC) Subject: Re: [PATCH v2 14/18] btrfs: extent_io: make endio_readpage_update_page_status() to handle subpage case To: Qu Wenruo , linux-btrfs@vger.kernel.org References: <20201210063905.75727-1-wqu@suse.com> <20201210063905.75727-15-wqu@suse.com> From: Nikolay Borisov Autocrypt: addr=nborisov@suse.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20201210063905.75727-15-wqu@suse.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 10.12.20 г. 8:39 ч., Qu Wenruo wrote: > To handle subpage status update, add the following new tricks: > - Use btrfs_page_*() helpers to update page status > Now we can handle both cases well. > > - No page unlock for subpage metadata > Since subpage metadata doesn't utilize page locking at all, skip it. > For subpage data locking, it's handled in later commits. > > Signed-off-by: Qu Wenruo > --- > fs/btrfs/extent_io.c | 23 +++++++++++++++++------ > 1 file changed, 17 insertions(+), 6 deletions(-) > > diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c > index 1ec9de2aa910..64a19c1884fc 100644 > --- a/fs/btrfs/extent_io.c > +++ b/fs/btrfs/extent_io.c > @@ -2841,15 +2841,26 @@ static void endio_readpage_release_extent(struct processed_extent *processed, > processed->uptodate = uptodate; > } > > -static void endio_readpage_update_page_status(struct page *page, bool uptodate) > +static void endio_readpage_update_page_status(struct page *page, bool uptodate, > + u64 start, u64 end) > { > + struct btrfs_fs_info *fs_info = btrfs_sb(page->mapping->host->i_sb); > + u32 len; > + > + ASSERT(page_offset(page) <= start && > + end <= page_offset(page) + PAGE_SIZE - 1); 'start' in this case is 'start = page_offset(page) + bvec->bv_offset;' from end_bio_extent_readpage, so it can't possibly be less than page_offset, instead it will at least be equal to page_offset if bvec->bv_offset is 0 . However, can we really guarantee this ? You are using the end only for the assert, and given you already have the 'len' parameter calculated in the caller I'd rather have this function take start/len, that would save you from recalculating the len and also for someone looking at the code it would be apparent it's the length of the currently processed bvec. I looked through the end of the series and you never use 'end' just 'len'