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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 0939BC433FF for ; Thu, 1 Aug 2019 18:09:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E132420838 for ; Thu, 1 Aug 2019 18:09:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732967AbfHASJP (ORCPT ); Thu, 1 Aug 2019 14:09:15 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:37517 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731642AbfHASJP (ORCPT ); Thu, 1 Aug 2019 14:09:15 -0400 Received: from pd9ef1cb8.dip0.t-ipconnect.de ([217.239.28.184] helo=nanos) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1htFVE-0006iz-PV; Thu, 01 Aug 2019 20:08:36 +0200 Date: Thu, 1 Aug 2019 20:08:30 +0200 (CEST) From: Thomas Gleixner To: Jan Kara cc: LKML , Peter Zijlstra , Ingo Molnar , Sebastian Siewior , Anna-Maria Gleixner , Steven Rostedt , Julia Cartwright , Jan Kara , linux-ext4@vger.kernel.org, Theodore Tso , Matthew Wilcox , Alexander Viro , linux-fsdevel@vger.kernel.org, Mark Fasheh , Joseph Qi , Joel Becker Subject: Re: [patch V2 7/7] fs/jbd2: Free journal head outside of locked region In-Reply-To: <20190801092223.GG25064@quack2.suse.cz> Message-ID: References: <20190801010126.245731659@linutronix.de> <20190801010944.549462805@linutronix.de> <20190801092223.GG25064@quack2.suse.cz> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Thu, 1 Aug 2019, Jan Kara wrote: > On Thu 01-08-19 03:01:33, Thomas Gleixner wrote: > > On PREEMPT_RT bit-spinlocks have the same semantics as on PREEMPT_RT=n, > > i.e. they disable preemption. That means functions which are not safe to be > > called in preempt disabled context on RT trigger a might_sleep() assert. > Looks mostly good. Just a small suggestion for simplification below: > > > @@ -2559,11 +2568,14 @@ void jbd2_journal_put_journal_head(struc > > J_ASSERT_JH(jh, jh->b_jcount > 0); > > --jh->b_jcount; > > if (!jh->b_jcount) { > > - __journal_remove_journal_head(bh); > > + size_t b_size = __journal_remove_journal_head(bh); > > + > > jbd_unlock_bh_journal_head(bh); > > + journal_release_journal_head(jh, b_size); > > __brelse(bh); > > The bh is pinned until you call __brelse(bh) above and bh->b_size doesn't > change during the lifetime of the buffer. So there's no need of > fetching bh->b_size in __journal_remove_journal_head() and passing it back. > You can just: > > journal_release_journal_head(jh, bh->b_size); Ah. Nice. I assumed that this would be possible, but then my ignorance induced paranoia won. Thanks, tglx