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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 5809AC48BE5 for ; Sat, 12 Jun 2021 21:35:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2DBA66109E for ; Sat, 12 Jun 2021 21:35:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231538AbhFLVhS (ORCPT ); Sat, 12 Jun 2021 17:37:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36002 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229753AbhFLVhR (ORCPT ); Sat, 12 Jun 2021 17:37:17 -0400 Received: from zeniv-ca.linux.org.uk (zeniv-ca.linux.org.uk [IPv6:2607:5300:60:148a::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 455F1C061574 for ; Sat, 12 Jun 2021 14:35:17 -0700 (PDT) Received: from viro by zeniv-ca.linux.org.uk with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1lsBHd-007RTu-CV; Sat, 12 Jun 2021 21:35:13 +0000 Date: Sat, 12 Jun 2021 21:35:13 +0000 From: Al Viro To: Andreas Gruenbacher Cc: Linus Torvalds , cluster-devel , Linux Kernel Mailing List , Jan Kara , Matthew Wilcox Subject: Re: [RFC 4/9] gfs2: Fix mmap + page fault deadlocks (part 1) Message-ID: References: <20210531170123.243771-1-agruenba@redhat.com> <20210531170123.243771-5-agruenba@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: Al Viro Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jun 12, 2021 at 09:05:40PM +0000, Al Viro wrote: > Is the above an accurate description of the mainline situation there? > In particular, normal read doesn't seem to bother with locks at all. > What exactly are those cluster locks for in O_DIRECT read? BTW, assuming the lack of contention, how costly is dropping/regaining such cluster lock? From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Viro Date: Sat, 12 Jun 2021 21:35:13 +0000 Subject: [Cluster-devel] [RFC 4/9] gfs2: Fix mmap + page fault deadlocks (part 1) In-Reply-To: References: <20210531170123.243771-1-agruenba@redhat.com> <20210531170123.243771-5-agruenba@redhat.com> Message-ID: List-Id: To: cluster-devel.redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Sat, Jun 12, 2021 at 09:05:40PM +0000, Al Viro wrote: > Is the above an accurate description of the mainline situation there? > In particular, normal read doesn't seem to bother with locks at all. > What exactly are those cluster locks for in O_DIRECT read? BTW, assuming the lack of contention, how costly is dropping/regaining such cluster lock?