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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D6EBCC77B75 for ; Sun, 7 May 2023 04:08:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=ICbuV9DaRWqJIh0ou+SvaSppa/eyvFSib+t6ZQrVuBE=; b=4Q+5QkYa2qwUye hi4KQfleq8Y0Wlc5AQc2ttrG4Xn7YoN3XIR+qkfjmgxuD6KaA/7sfcanwE+vYYZvtGRMw5mpf4g7I tCp+gSuNlsS93Gx0p0No6WZ3D8tMaNorI5atftjGPg2KY5Qg89lCGDwxpfbAObEdcnX+uQaU8GR8F ywad1SgzawlkRAh7+KuFnBCqXwXLXt1jPOVbPXUz8THDCD7DDuYvFniBCu89GGqGaYcQUP0FaHl41 ikKXJH7lQZ4l4rcijF3IkIrwDbe5np0+vl7ycFRcGRn8EPe4RPrglb4GkzJ+5NyzFEp2QjLfmPPMI EPtvijGnct/8DqI/H86Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1pvVhM-00F7aF-0k; Sun, 07 May 2023 04:08:36 +0000 Received: from mcgrof by bombadil.infradead.org with local (Exim 4.96 #2 (Red Hat Linux)) id 1pvVhL-00F7Zt-0g; Sun, 07 May 2023 04:08:35 +0000 Date: Sat, 6 May 2023 21:08:35 -0700 From: Luis Chamberlain To: Jan Kara Cc: "Darrick J. Wong" , hch@infradead.org, song@kernel.org, rafael@kernel.org, gregkh@linuxfoundation.org, viro@zeniv.linux.org.uk, bvanassche@acm.org, ebiederm@xmission.com, mchehab@kernel.org, keescook@chromium.org, p.raghav@samsung.com, linux-fsdevel@vger.kernel.org, kernel@tuxforce.de, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, xfs Subject: Re: [RFC v3 03/24] fs: distinguish between user initiated freeze and kernel initiated freeze Message-ID: References: <20230114003409.1168311-1-mcgrof@kernel.org> <20230114003409.1168311-4-mcgrof@kernel.org> <20230118092812.2gl3cde6mocbngli@quack3> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20230118092812.2gl3cde6mocbngli@quack3> X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On Wed, Jan 18, 2023 at 10:28:12AM +0100, Jan Kara wrote: > On Tue 17-01-23 18:25:40, Darrick J. Wong wrote: > > [add linux-xfs to cc on this one] > > > > On Fri, Jan 13, 2023 at 04:33:48PM -0800, Luis Chamberlain wrote: > > > Userspace can initiate a freeze call using ioctls. If the kernel decides > > > to freeze a filesystem later it must be able to distinguish if userspace > > > had initiated the freeze, so that it does not unfreeze it later > > > automatically on resume. > > > > Hm. Zooming out a bit here, I want to think about how kernel freezes > > should behave... > > > > > Likewise if the kernel is initiating a freeze on its own it should *not* > > > fail to freeze a filesystem if a user had already frozen it on our behalf. > > > > ...because kernel freezes can absorb an existing userspace freeze. Does > > that mean that userspace should be prevented from undoing a kernel > > freeze? Even in that absorption case? > > > > Also, should we permit multiple kernel freezes of the same fs at the > > same time? And if we do allow that, would they nest like freeze used to > > do? > > > > (My suggestions here are 'yes', 'yes', and '**** no'.) > > Yeah, makes sense to me. So I think the mental model to make things safe > is that there are two flags - frozen_by_user, frozen_by_kernel - and the > superblock is kept frozen as long as either of these is set. Makes sense to me. Luis _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec