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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 7D58FC43387 for ; Fri, 4 Jan 2019 15:29:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 54EE320874 for ; Fri, 4 Jan 2019 15:29:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727321AbfADP3t (ORCPT ); Fri, 4 Jan 2019 10:29:49 -0500 Received: from mx2.suse.de ([195.135.220.15]:56212 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726948AbfADP3t (ORCPT ); Fri, 4 Jan 2019 10:29:49 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 33791ACFB for ; Fri, 4 Jan 2019 15:29:48 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id D6CA1DA7CE; Fri, 4 Jan 2019 16:29:18 +0100 (CET) Date: Fri, 4 Jan 2019 16:29:18 +0100 From: David Sterba To: Nikolay Borisov Cc: linux-btrfs@vger.kernel.org Subject: Re: [PATCH 3/7] btrfs: Use ihold instead of igrab in cow_file_range_async Message-ID: <20190104152918.GP23615@twin.jikos.cz> Reply-To: dsterba@suse.cz Mail-Followup-To: dsterba@suse.cz, Nikolay Borisov , linux-btrfs@vger.kernel.org References: <20190103085005.32053-1-nborisov@suse.com> <20190103085005.32053-4-nborisov@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190103085005.32053-4-nborisov@suse.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Thu, Jan 03, 2019 at 10:50:01AM +0200, Nikolay Borisov wrote: > ihold is supposed to be used when the caller already has a reference to > the inode. In the case of cow_file_range_async this invariants holds, > since the 3 call chains leading to this function all take a reference: > > btrfs_writepage <--- does igrab > extent_write_full_page > __extent_writepage > writepage_delalloc > btrfs_run_delalloc_range > cow_file_range_async > > extent_write_cache_pages <--- does igrab > __extent_writepage (same callchain as above) > > and > > submit_compressed_extents <-- already called from async CoW submit path, > which would have done ihold. > extent_write_locked_range > __extent_writepage So by the logic the inode reference needs to be taken early, eg. in btrfs_writepage and all low-level callbacks or helpers are fine with ihold. Reviewed-by: David Sterba