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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 B36D3C433B4 for ; Wed, 7 Apr 2021 08:00:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7CBA160BD3 for ; Wed, 7 Apr 2021 08:00:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235138AbhDGIBA (ORCPT ); Wed, 7 Apr 2021 04:01:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46564 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229529AbhDGIBA (ORCPT ); Wed, 7 Apr 2021 04:01:00 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C2A21C06174A for ; Wed, 7 Apr 2021 01:00:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=IkpPbvAt8IQqpxNdm/uEA3XybkUDzIUK4FC0f/Rtuvw=; b=B5f21vQW1xslzB6FNl8iMLLtqi pPl97j957u+m4GzDWPokFfR6Jyn4LG++IkzJU+VhHs+1p/HA5oTSMndanVRCbFNUy6LNJoRSyfvLj F8/Y+CH4tJiwykbUnAdds+f+PqDL+tA4icId5RVWJyewA+nYEw3GgO5XLPtlpD5rykY5S7QKBJRRs g0Xh9YWAX4nLdQfsPByjjNmvPq65N3p3MSD4fLuKQBHk3Bj8kcfUls2vFn5DT1EuTsSGhpj+tg5ni ivbJQja/39HJBljEiyuhSNYzZRSTTBkDHRi7hv1jDm0bDqfZHrQszSBa/jin8T+NqmVUCbh9Lp96e /LyyzGuw==; Received: from hch by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1lU37B-00E7o1-79; Wed, 07 Apr 2021 08:00:43 +0000 Date: Wed, 7 Apr 2021 09:00:41 +0100 From: Christoph Hellwig To: Brian Foster Cc: linux-xfs@vger.kernel.org Subject: Re: [PATCH v2 2/3] xfs: transaction subsystem quiesce mechanism Message-ID: <20210407080041.GB3363884@infradead.org> References: <20210406144238.814558-1-bfoster@redhat.com> <20210406144238.814558-3-bfoster@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210406144238.814558-3-bfoster@redhat.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Tue, Apr 06, 2021 at 10:42:37AM -0400, Brian Foster wrote: > The updated quotaoff logging algorithm depends on a runtime quiesce > of the transaction subsystem to guarantee all transactions after a > certain point detect quota subsystem changes. Implement this > mechanism using an internal lock, similar to the external filesystem > freeze mechanism. This is also somewhat analogous to the old percpu > transaction counter mechanism, but we don't actually need a counter. Stupid question that already came up when seeing the replies to my s_inodes patch: Why do we even care about quotaoff? Is there any real life use case for quotaoff, at least the kind that disables accounting (vs enforcement)? IMHO we spend a lot of effort on this corner case that has no practical value, and just removing support for quotaoff might serve us much better in the long run.