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=-7.2 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,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 AB11AC4338F for ; Mon, 23 Aug 2021 15:11:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8ED8B61037 for ; Mon, 23 Aug 2021 15:11:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229933AbhHWPMM (ORCPT ); Mon, 23 Aug 2021 11:12:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39928 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231140AbhHWPML (ORCPT ); Mon, 23 Aug 2021 11:12:11 -0400 Received: from fieldses.org (fieldses.org [IPv6:2600:3c00:e000:2f7::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DA5B7C061575 for ; Mon, 23 Aug 2021 08:11:27 -0700 (PDT) Received: by fieldses.org (Postfix, from userid 2815) id 368826855; Mon, 23 Aug 2021 11:11:27 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.11.0 fieldses.org 368826855 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fieldses.org; s=default; t=1629731487; bh=zHsshka57LdVeAEwBFskmUltem0scBimosKO/3TgeyM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=HZBBZT9BNCGDd2do3JSwG972J3O4yAz0zoEPshfbSvTP1B93x+3XAfbl3QShCVDIK VOtfpL/5nz0TAt6Lt262AvjCYf5KLfAMBZNfST+5+aGpgqY7QnUm5V9TlPkZBc6BHL TnC8cFaoAW06Xi02zmcR8B8jBm3pPjoz8kWlUFpU= Date: Mon, 23 Aug 2021 11:11:27 -0400 From: "bfields@fieldses.org" To: Trond Myklebust Cc: "linux-nfs@vger.kernel.org" Subject: Re: sporadic generic/154 failure Message-ID: <20210823151127.GB883@fieldses.org> References: <20210823144802.GA883@fieldses.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On Mon, Aug 23, 2021 at 03:06:21PM +0000, Trond Myklebust wrote: > On Mon, 2021-08-23 at 10:48 -0400, J. Bruce Fields wrote: > > I'm seeing generic/154 failing sometimes. > > > > It does a "cp --reflink" (which uses FI_CLONE, which results in a > > ->remap_file_range call that NFS maps to the CLONE operation), then > > overwriting parts of the fire, and checking free blocks (with "stat -f > > /path -c "%f") at various points, and failing when the number of free > > blocks is outside an expected range. > > > > I don't know if it might be some caching issue, or something about how > > NFS reports free blocks. > > > > Honestly it looks unlikely to be critical, so for now I'm ignoring > > it.... > > > > XFS backend? Yes. > It could be speculative preallocation. The fact that NFS > can defer closing the file (either due to delegations or due to the > NFSv3 file cache) typically results in it taking longer for XFS to free > up the blocks it preallocated. That again means it takes longer for the > 'space used' to settle to the correct final value. > > https://linux-xfs.oss.sgi.narkive.com/jjjfnyI1/faq-xfs-speculative-preallocation That sounds plausible. --b.