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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 C8D31C3276D for ; Thu, 2 Jan 2020 07:48:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A06FD21734 for ; Thu, 2 Jan 2020 07:48:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727721AbgABHrL (ORCPT ); Thu, 2 Jan 2020 02:47:11 -0500 Received: from mx2.suse.de ([195.135.220.15]:48288 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726145AbgABHrL (ORCPT ); Thu, 2 Jan 2020 02:47:11 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 0E4F2AD5E for ; Thu, 2 Jan 2020 07:47:10 +0000 (UTC) From: Qu Wenruo To: linux-btrfs@vger.kernel.org Subject: [PATCH 0/4] Introduce per-profile available space array to avoid over-confident can_overcommit() Date: Thu, 2 Jan 2020 15:47:01 +0800 Message-Id: <20200102074705.136348-1-wqu@suse.com> X-Mailer: git-send-email 2.24.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org There are several bug reports of ENOSPC error in btrfs_run_delalloc_range(). With some extra info from one reporter, it turns out that can_overcommit() is using a wrong way to calculate allocatable metadata space. The most typical case would look like: devid 1 unallocated: 1G devid 2 unallocated: 10G metadata profile: RAID1 In above case, we can at most allocate 1G chunk for metadata, due to unbalanced disk free space. But current can_overcommit() uses factor based calculation, which never consider the disk free space balance. To address this problem, here comes the per-profile available space array, which gets updated every time a chunk get allocated/removed or a device get grown or shrunk. This provides a quick way for hotter place like can_overcommit() to grab an estimation on how many bytes it can over-commit. The per-profile available space calculation tries to keep the behavior of chunk allocator, thus it can handle uneven disks pretty well. Although per-profile is not clever enough to handle estimation when both data and metadata chunks need to be considered, its virtual chunk infrastructure is flex enough to handle such case. So for statfs(), we also re-use virtual chunk allocator to handle available data space, with metadata over-commit space considered. This brings an unexpected advantage, now we can handle RAID5/6 pretty OK in statfs(). Changelog: v1: - Fix a bug where we forgot to update per-profile array after allocating a chunk. To avoid ABBA deadlock, this introduce a small windows at the end __btrfs_alloc_chunk(), it's not elegant but should be good enough before we rework chunk and device list mutex. - Make statfs() to use virtual chunk allocator to do better estimation Now statfs() can report not only more accurate result, but can also handle RAID5/6 better. Qu Wenruo (4): btrfs: Introduce per-profile available space facility btrfs: Update per-profile available space when device size/used space get updated btrfs: space-info: Use per-profile available space in can_overcommit() btrfs: statfs: Use virtual chunk allocation to calculation available data space fs/btrfs/space-info.c | 15 ++- fs/btrfs/super.c | 190 +++++++++++++---------------------- fs/btrfs/volumes.c | 223 ++++++++++++++++++++++++++++++++++++++---- fs/btrfs/volumes.h | 14 +++ 4 files changed, 293 insertions(+), 149 deletions(-) -- 2.24.1