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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable 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 C49D2C11D00 for ; Fri, 21 Feb 2020 01:26:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9C7E0208E4 for ; Fri, 21 Feb 2020 01:26:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729558AbgBUB0d (ORCPT ); Thu, 20 Feb 2020 20:26:33 -0500 Received: from mail104.syd.optusnet.com.au ([211.29.132.246]:59810 "EHLO mail104.syd.optusnet.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729476AbgBUB0c (ORCPT ); Thu, 20 Feb 2020 20:26:32 -0500 Received: from dread.disaster.area (pa49-195-185-106.pa.nsw.optusnet.com.au [49.195.185.106]) by mail104.syd.optusnet.com.au (Postfix) with ESMTPS id EF33682017D; Fri, 21 Feb 2020 12:26:26 +1100 (AEDT) Received: from dave by dread.disaster.area with local (Exim 4.92.3) (envelope-from ) id 1j4x5F-000591-FM; Fri, 21 Feb 2020 12:26:25 +1100 Date: Fri, 21 Feb 2020 12:26:25 +1100 From: Dave Chinner To: ira.weiny@intel.com Cc: linux-kernel@vger.kernel.org, Alexander Viro , "Darrick J. Wong" , Dan Williams , Christoph Hellwig , "Theodore Y. Ts'o" , Jan Kara , linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH V4 01/13] fs/xfs: Remove unnecessary initialization of i_rwsem Message-ID: <20200221012625.GT10776@dread.disaster.area> References: <20200221004134.30599-1-ira.weiny@intel.com> <20200221004134.30599-2-ira.weiny@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200221004134.30599-2-ira.weiny@intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.3 cv=LYdCFQXi c=1 sm=1 tr=0 a=bkRQb8bsQZKWSSj4M57YXw==:117 a=bkRQb8bsQZKWSSj4M57YXw==:17 a=jpOVt7BSZ2e4Z31A5e1TngXxSK0=:19 a=kj9zAlcOel0A:10 a=l697ptgUJYAA:10 a=QyXUC8HyAAAA:8 a=7-415B0cAAAA:8 a=V8yeCck6NC70EfR_wKwA:9 a=CjuIK1q_8ugA:10 a=biEYGPWJfzWAr4FL6Ov7:22 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Thu, Feb 20, 2020 at 04:41:22PM -0800, ira.weiny@intel.com wrote: > From: Ira Weiny > > xfs_reinit_inode() -> inode_init_always() already handles calling > init_rwsem(i_rwsem). Doing so again is unneeded. > > Signed-off-by: Ira Weiny Except that this inode has been destroyed and freed by the VFS, and we are now recycling it back into the VFS before we actually physically freed it. Hence we have re-initialise the semaphore because the semaphore can contain internal state that is specific to it's new life cycle (e.g. the lockdep context) that will cause problems if we just assume that the inode is the same inode as it was before we recycled it back into the VFS caches. So, yes, we actually do need to re-initialise the rwsem here. Cheers, Dave. -- Dave Chinner david@fromorbit.com