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=-15.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,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 27BD4C433DB for ; Wed, 27 Jan 2021 17:15:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C729964D99 for ; Wed, 27 Jan 2021 17:15:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232132AbhA0RPr (ORCPT ); Wed, 27 Jan 2021 12:15:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52040 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233624AbhA0ROv (ORCPT ); Wed, 27 Jan 2021 12:14:51 -0500 Received: from mail-qk1-x734.google.com (mail-qk1-x734.google.com [IPv6:2607:f8b0:4864:20::734]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 51533C06178C for ; Wed, 27 Jan 2021 09:13:30 -0800 (PST) Received: by mail-qk1-x734.google.com with SMTP id a19so2450612qka.2 for ; Wed, 27 Jan 2021 09:13:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=toxicpanda-com.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=xrnPNg9PW24xoNDW3O+I/Ll+vPfkshD6140tic6uKrA=; b=2MJazwrf9PqPW2+5Wg8NV8BrY4mPjNZJKxg9XEaCjJ+POBPzvtvARE286vz3gDpmu1 l29geoy2ElDj5ERhC2isGvcI/4OlMittWfgpT0YZYLuCEdFDj19W8jUpuXNQPgWd+SNj EHI+9RHaKIoVXcgJD3tZVVX2XFG8W5nMSt8x2Ou2hXXMkUnc0aHuF4GSGCkYiRicYYPH Mfl1w3H5TeOBGKV3/anKyZM18JWwp8fWev5AZVdTMeQb08BEIfqWyUDEM1cC9nQ9KtSZ grkklgN7RM8rNeLi5+Fgyz6E6Oc0dxry1zzxaHI3iuQpD+qfyknqs7OUJxtDLSt9Lvb4 itOA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=xrnPNg9PW24xoNDW3O+I/Ll+vPfkshD6140tic6uKrA=; b=KUJ9udc2CGnJqUt3EzUwfuDYGY6eKQPR+LzDkPhB1WXWmVKu0bi4glbhFxkE3DLR/b UGRwm0T6YwVft9xM89IRGHX+D5YT9ARA8uMjFdim4FFcaR4nkYBMDyispQq3vl2wKLtR q1iR0/mibZlbv9S+At9VecuSrajdF9hd89+Yuwh7yiwJeAACXxW0Ifm2WnOSjbtWvXmF q63TZmj7lI8e57t/HK9uWtG3l+lojSajM7dES5PnpSK8M8FYrwey50IXzvGUZGO9A2Zg I+23D4U9opSEK+DOC7/uos9HprP9OHf79ST6mg8YE/f/SRdHQk/50DLlz/YCoBUJJjE5 LPfA== X-Gm-Message-State: AOAM5327MKoLoy2gD5wnt0dSLsHRdlkdoe3LAPoEVkA8VERAdk2/cJuw mCWQx1JD90Qo/bSdgrbwQp4Q6PGGzvx53VQ2 X-Google-Smtp-Source: ABdhPJxSRprdhzZ2g5mD1RmJ8PzqFirsIn5QUIQzPeIfHCg0t60CNs9ZxLCBledv83eO1F9/8fTekQ== X-Received: by 2002:a37:4116:: with SMTP id o22mr11410605qka.236.1611767609410; Wed, 27 Jan 2021 09:13:29 -0800 (PST) Received: from [192.168.1.45] (cpe-174-109-172-136.nc.res.rr.com. [174.109.172.136]) by smtp.gmail.com with ESMTPSA id 202sm1575285qkj.92.2021.01.27.09.13.28 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 27 Jan 2021 09:13:28 -0800 (PST) Subject: Re: [PATCH v5 17/18] btrfs: integrate page status update for data read path into begin/end_page_read() To: Qu Wenruo , linux-btrfs@vger.kernel.org Cc: David Sterba References: <20210126083402.142577-1-wqu@suse.com> <20210126083402.142577-18-wqu@suse.com> From: Josef Bacik Message-ID: Date: Wed, 27 Jan 2021 12:13:27 -0500 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: <20210126083402.142577-18-wqu@suse.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 1/26/21 3:34 AM, Qu Wenruo wrote: > In btrfs data page read path, the page status update are handled in two > different locations: > > btrfs_do_read_page() > { > while (cur <= end) { > /* No need to read from disk */ > if (HOLE/PREALLOC/INLINE){ > memset(); > set_extent_uptodate(); > continue; > } > /* Read from disk */ > ret = submit_extent_page(end_bio_extent_readpage); > } > > end_bio_extent_readpage() > { > endio_readpage_uptodate_page_status(); > } > > This is fine for sectorsize == PAGE_SIZE case, as for above loop we > should only hit one branch and then exit. > > But for subpage, there are more works to be done in page status update: > - Page Unlock condition > Unlike regular page size == sectorsize case, we can no longer just > unlock a page without a brain. > Only the last reader of the page can unlock the page. > This means, we can unlock the page either in the while() loop, or in > the endio function. > > - Page uptodate condition > Since we have multiple sectors to read for a page, we can only mark > the full page uptodate if all sectors are uptodate. > > To handle both subpage and regular cases, introduce a pair of functions > to help handling page status update: > > - being_page_read() > For regular case, it does nothing. > For subpage case, it update the reader counters so that later > end_page_read() can know who is the last one to unlock the page. > > - end_page_read() > This is just endio_readpage_uptodate_page_status() renamed. > The original name is a little too long and too specific for endio. > > The only new trick added is the condition for page unlock. > Now for subage data, we unlock the page if we're the last reader. > > This does not only provide the basis for subpage data read, but also > hide the special handling of page read from the main read loop. > > Signed-off-by: Qu Wenruo > Signed-off-by: David Sterba > --- > fs/btrfs/extent_io.c | 38 ++++++++++++++++++++---------- > fs/btrfs/subpage.c | 56 ++++++++++++++++++++++++++++++++++---------- > fs/btrfs/subpage.h | 8 +++++++ > 3 files changed, 78 insertions(+), 24 deletions(-) > > diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c > index eeee3213daaa..7fc2c62d4eb9 100644 > --- a/fs/btrfs/extent_io.c > +++ b/fs/btrfs/extent_io.c > @@ -2839,8 +2839,17 @@ 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, > - u64 start, u32 len) > +static void begin_data_page_read(struct btrfs_fs_info *fs_info, struct page *page) > +{ > + ASSERT(PageLocked(page)); > + if (fs_info->sectorsize == PAGE_SIZE) > + return; > + > + ASSERT(PagePrivate(page)); > + btrfs_subpage_start_reader(fs_info, page, page_offset(page), PAGE_SIZE); > +} > + > +static void end_page_read(struct page *page, bool uptodate, u64 start, u32 len) > { > struct btrfs_fs_info *fs_info = btrfs_sb(page->mapping->host->i_sb); > > @@ -2856,7 +2865,12 @@ static void endio_readpage_update_page_status(struct page *page, bool uptodate, > > if (fs_info->sectorsize == PAGE_SIZE) > unlock_page(page); > - /* Subpage locking will be handled in later patches */ > + else if (is_data_inode(page->mapping->host)) > + /* > + * For subpage data, unlock the page if we're the last reader. > + * For subpage metadata, page lock is not utilized for read. > + */ > + btrfs_subpage_end_reader(fs_info, page, start, len); > } > > /* > @@ -2993,7 +3007,7 @@ static void end_bio_extent_readpage(struct bio *bio) > bio_offset += len; > > /* Update page status and unlock */ > - endio_readpage_update_page_status(page, uptodate, start, len); > + end_page_read(page, uptodate, start, len); > endio_readpage_release_extent(&processed, BTRFS_I(inode), > start, end, uptodate); > } > @@ -3263,6 +3277,7 @@ int btrfs_do_readpage(struct page *page, struct extent_map **em_cached, > unsigned int read_flags, u64 *prev_em_start) > { > struct inode *inode = page->mapping->host; > + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); > u64 start = page_offset(page); > const u64 end = start + PAGE_SIZE - 1; > u64 cur = start; > @@ -3306,6 +3321,7 @@ int btrfs_do_readpage(struct page *page, struct extent_map **em_cached, > kunmap_atomic(userpage); > } > } You have two error cases above this ret = set_page_extent_mapped(page); if (ret < 0) { unlock_extent(tree, start, end); SetPageError(page); goto out; } and if (!PageUptodate(page)) { if (cleancache_get_page(page) == 0) { BUG_ON(blocksize != PAGE_SIZE); unlock_extent(tree, start, end); goto out; } } which will now leave the page locked when it errors out. Not to mention I'm pretty sure you want to use btrfs_page_set_error() instead of SetPageError() in that first case. > + begin_data_page_read(fs_info, page); > while (cur <= end) { > bool force_bio_submit = false; > u64 disk_bytenr; > @@ -3323,13 +3339,14 @@ int btrfs_do_readpage(struct page *page, struct extent_map **em_cached, > &cached, GFP_NOFS); > unlock_extent_cached(tree, cur, > cur + iosize - 1, &cached); > + end_page_read(page, true, cur, iosize); > break; > } > em = __get_extent_map(inode, page, pg_offset, cur, > end - cur + 1, em_cached); > if (IS_ERR_OR_NULL(em)) { > - SetPageError(page); > unlock_extent(tree, cur, end); > + end_page_read(page, false, cur, end + 1 - cur); > break; > } > extent_offset = cur - em->start; > @@ -3412,6 +3429,7 @@ int btrfs_do_readpage(struct page *page, struct extent_map **em_cached, > &cached, GFP_NOFS); > unlock_extent_cached(tree, cur, > cur + iosize - 1, &cached); > + end_page_read(page, true, cur, iosize); > cur = cur + iosize; > pg_offset += iosize; > continue; > @@ -3421,6 +3439,7 @@ int btrfs_do_readpage(struct page *page, struct extent_map **em_cached, > EXTENT_UPTODATE, 1, NULL)) { > check_page_uptodate(tree, page); > unlock_extent(tree, cur, cur + iosize - 1); > + end_page_read(page, true, cur, iosize); > cur = cur + iosize; > pg_offset += iosize; > continue; > @@ -3429,8 +3448,8 @@ int btrfs_do_readpage(struct page *page, struct extent_map **em_cached, > * to date. Error out > */ > if (block_start == EXTENT_MAP_INLINE) { > - SetPageError(page); > unlock_extent(tree, cur, cur + iosize - 1); > + end_page_read(page, false, cur, iosize); > cur = cur + iosize; > pg_offset += iosize; > continue; > @@ -3447,19 +3466,14 @@ int btrfs_do_readpage(struct page *page, struct extent_map **em_cached, > nr++; > *bio_flags = this_bio_flag; > } else { > - SetPageError(page); > unlock_extent(tree, cur, cur + iosize - 1); > + end_page_read(page, false, cur, iosize); > goto out; > } > cur = cur + iosize; > pg_offset += iosize; > } > out: > - if (!nr) { > - if (!PageError(page)) > - SetPageUptodate(page); > - unlock_page(page); > - } We can just delete out: here and either return on error or break from the main loop. Thanks, Josef