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=-9.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_GIT 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 02486ECDE46 for ; Thu, 25 Oct 2018 14:20:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B9DCB21479 for ; Thu, 25 Oct 2018 14:20:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="P9hoHSkf" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B9DCB21479 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731003AbeJYWxW (ORCPT ); Thu, 25 Oct 2018 18:53:22 -0400 Received: from mail.kernel.org ([198.145.29.99]:35828 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729116AbeJYWxU (ORCPT ); Thu, 25 Oct 2018 18:53:20 -0400 Received: from sasha-vm.mshome.net (unknown [167.98.65.38]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1AAC82085B; Thu, 25 Oct 2018 14:20:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1540477223; bh=rzIYP/HxjVSvM6JjY20sjazP/W8+Kraft4kpjxdt3+E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=P9hoHSkf3OgGLVf2tmq43d61TLHhObALk946mZA1B5DulN4nnJL+U2l2jcCzVgCQz Pfr+T9hVUHFweWN/sepL2sTw7VAncMexqYFnE8QXYUN1XvdsOQKdL50+nXqXZ/BHs1 5zPPIOtJN4Qxw6/Uc6U5594ek7gcQwN1ivknznWE= From: Sasha Levin To: stable@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Filipe Manana , Chris Mason , Sasha Levin Subject: [PATCH AUTOSEL 3.18 58/98] Btrfs: avoid syncing log in the fast fsync path when not necessary Date: Thu, 25 Oct 2018 10:18:13 -0400 Message-Id: <20181025141853.214051-58-sashal@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181025141853.214051-1-sashal@kernel.org> References: <20181025141853.214051-1-sashal@kernel.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Filipe Manana [ Upstream commit b659ef027792219b590d67a2baf1643a93727d29 ] Commit 3a8b36f37806 ("Btrfs: fix data loss in the fast fsync path") added a performance regression for that causes an unnecessary sync of the log trees (fs/subvol and root log trees) when 2 consecutive fsyncs are done against a file, without no writes or any metadata updates to the inode in between them and if a transaction is committed before the second fsync is called. Huang Ying reported this to lkml (https://lkml.org/lkml/2015/3/18/99) after a test sysbench test that measured a -62% decrease of file io requests per second for that tests' workload. The test is: echo performance > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor echo performance > /sys/devices/system/cpu/cpu1/cpufreq/scaling_governor echo performance > /sys/devices/system/cpu/cpu2/cpufreq/scaling_governor echo performance > /sys/devices/system/cpu/cpu3/cpufreq/scaling_governor mkfs -t btrfs /dev/sda2 mount -t btrfs /dev/sda2 /fs/sda2 cd /fs/sda2 for ((i = 0; i < 1024; i++)); do fallocate -l 67108864 testfile.$i; done sysbench --test=fileio --max-requests=0 --num-threads=4 --max-time=600 \ --file-test-mode=rndwr --file-total-size=68719476736 --file-io-mode=sync \ --file-num=1024 run A test on kvm guest, running a debug kernel gave me the following results: Without 3a8b36f378060d: 16.01 reqs/sec With 3a8b36f378060d: 3.39 reqs/sec With 3a8b36f378060d and this patch: 16.04 reqs/sec Reported-by: Huang Ying Tested-by: Huang, Ying Signed-off-by: Filipe Manana Signed-off-by: Chris Mason Signed-off-by: Sasha Levin --- fs/btrfs/file.c | 9 ++++++--- fs/btrfs/ordered-data.c | 14 ++++++++++++++ fs/btrfs/ordered-data.h | 3 +++ 3 files changed, 23 insertions(+), 3 deletions(-) diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 2ad4cb3da8f6..ba37ec6263ca 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1879,6 +1879,7 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync) struct btrfs_log_ctx ctx; int ret = 0; bool full_sync = 0; + const u64 len = end - start + 1; trace_btrfs_sync_file(file, datasync); @@ -1907,7 +1908,7 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync) * all extents are persisted and the respective file extent * items are in the fs/subvol btree. */ - ret = btrfs_wait_ordered_range(inode, start, end - start + 1); + ret = btrfs_wait_ordered_range(inode, start, len); } else { /* * Start any new ordered operations before starting to log the @@ -1979,8 +1980,10 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync) */ smp_mb(); if (btrfs_inode_in_log(inode, root->fs_info->generation) || - (full_sync && BTRFS_I(inode)->last_trans <= - root->fs_info->last_trans_committed)) { + (BTRFS_I(inode)->last_trans <= + root->fs_info->last_trans_committed && + (full_sync || + !btrfs_have_ordered_extents_in_range(inode, start, len)))) { /* * We'v had everything committed since the last time we were * modified so clear this flag in case it was set for whatever diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c index b23d024c0234..4c20199cef62 100644 --- a/fs/btrfs/ordered-data.c +++ b/fs/btrfs/ordered-data.c @@ -848,6 +848,20 @@ struct btrfs_ordered_extent *btrfs_lookup_ordered_range(struct inode *inode, return entry; } +bool btrfs_have_ordered_extents_in_range(struct inode *inode, + u64 file_offset, + u64 len) +{ + struct btrfs_ordered_extent *oe; + + oe = btrfs_lookup_ordered_range(inode, file_offset, len); + if (oe) { + btrfs_put_ordered_extent(oe); + return true; + } + return false; +} + /* * lookup and return any extent before 'file_offset'. NULL is returned * if none is found diff --git a/fs/btrfs/ordered-data.h b/fs/btrfs/ordered-data.h index 0124bffc775f..a1bce0a5cccc 100644 --- a/fs/btrfs/ordered-data.h +++ b/fs/btrfs/ordered-data.h @@ -191,6 +191,9 @@ btrfs_lookup_first_ordered_extent(struct inode * inode, u64 file_offset); struct btrfs_ordered_extent *btrfs_lookup_ordered_range(struct inode *inode, u64 file_offset, u64 len); +bool btrfs_have_ordered_extents_in_range(struct inode *inode, + u64 file_offset, + u64 len); int btrfs_ordered_update_i_size(struct inode *inode, u64 offset, struct btrfs_ordered_extent *ordered); int btrfs_find_ordered_sum(struct inode *inode, u64 offset, u64 disk_bytenr, -- 2.17.1