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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT 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 9F1DFC31E46 for ; Wed, 12 Jun 2019 14:04:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7BCE820896 for ; Wed, 12 Jun 2019 14:04:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2409262AbfFLOEw (ORCPT ); Wed, 12 Jun 2019 10:04:52 -0400 Received: from mx2.suse.de ([195.135.220.15]:37982 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2407368AbfFLOEw (ORCPT ); Wed, 12 Jun 2019 10:04:52 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id E134CB01F; Wed, 12 Jun 2019 14:04:50 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id 8BF8BDA88C; Wed, 12 Jun 2019 16:05:41 +0200 (CEST) Date: Wed, 12 Jun 2019 16:05:41 +0200 From: David Sterba To: Nikolay Borisov Cc: linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, andrea.parri@amarulasolutions.com, peterz@infradead.org, paulmck@linux.ibm.com Subject: Re: [PATCH 1/2] btrfs: Implement DRW lock Message-ID: <20190612140541.GL3563@twin.jikos.cz> Reply-To: dsterba@suse.cz Mail-Followup-To: dsterba@suse.cz, Nikolay Borisov , linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, andrea.parri@amarulasolutions.com, peterz@infradead.org, paulmck@linux.ibm.com References: <20190606135219.1086-1-nborisov@suse.com> <20190606135219.1086-2-nborisov@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190606135219.1086-2-nborisov@suse.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 06, 2019 at 04:52:18PM +0300, Nikolay Borisov wrote: > A (D)ouble (R)eader (W)riter lock is a locking primitive that allows > to have multiple readers or multiple writers but not multiple readers > and writers holding it concurrently. The code is factored out from > the existing open-coded locking scheme used to exclude pending > snapshots from nocow writers and vice-versa. Current implementation > actually favors Readers (that is snapshot creaters) to writers (nocow > writers of the filesystem). > > Signed-off-by: Nikolay Borisov > --- > fs/btrfs/Makefile | 2 +- > fs/btrfs/drw_lock.c | 71 +++++++++++++++++++++++++++++++++++++++++++++ > fs/btrfs/drw_lock.h | 23 +++++++++++++++ In v2, please use locking.[ch] instead of new files.