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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 5540FC4361B for ; Thu, 17 Dec 2020 15:04:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0E104235F9 for ; Thu, 17 Dec 2020 15:04:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727185AbgLQPEZ (ORCPT ); Thu, 17 Dec 2020 10:04:25 -0500 Received: from mx2.suse.de ([195.135.220.15]:52404 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726983AbgLQPEY (ORCPT ); Thu, 17 Dec 2020 10:04:24 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 9BAD5AC7B; Thu, 17 Dec 2020 15:03:43 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id A0290DA83A; Thu, 17 Dec 2020 16:02:03 +0100 (CET) Date: Thu, 17 Dec 2020 16:02:03 +0100 From: David Sterba To: fdmanana@kernel.org Cc: linux-btrfs@vger.kernel.org, josef@toxicpanda.com, Filipe Manana Subject: Re: [PATCH 0/2] btrfs: fix races between clone, fallocate and memory mapped writes Message-ID: <20201217150203.GP6430@twin.jikos.cz> Reply-To: dsterba@suse.cz Mail-Followup-To: dsterba@suse.cz, fdmanana@kernel.org, linux-btrfs@vger.kernel.org, josef@toxicpanda.com, Filipe Manana References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Mon, Dec 14, 2020 at 09:56:40AM +0000, fdmanana@kernel.org wrote: > From: Filipe Manana > > For a very long time there's been a race between clone/dedupe and memory > mapped writes as well as between fallocate and memory mapped writes. For > both cases the consequence of the race is that it can makes us deadlock > when we are low on available metadata space, since clone/dedupe/fallocate > start a transaction while holding file ranges locked, and allocating the > metadata can result in the async reclaim task to flush the inodes being > used by clone/dedupe/fallocate, if a memory mapped write happened before > we locked the file ranges. > > For the dedupe case, Josef's recent fix [1] ("btrfs: fix race between dedupe > and mmap") happens to fix this deadlock problem as well. The first patch > in this patchset fixes the issue for both clone and dedupe, as it's centered > on the shared extent locking function, and it is independent of Josef's fix > (works both with and without that fix). Thanks, I was wondering how all the patches are related. > > [1] https://lore.kernel.org/linux-btrfs/afdc2109f83fff1a925d7a66a6a047d4400721d4.1607724668.git.josef@toxicpanda.com/ > > Filipe Manana (2): > btrfs: fix race between cloning and memory mapped writes leading to > deadlock > btrfs: fix race between fallocate and memory mapped writes leading to > deadlock Added to misc-next, thanks.