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=-9.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 B78B0C433E2 for ; Mon, 14 Sep 2020 23:33:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 799BC2193E for ; Mon, 14 Sep 2020 23:33:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725999AbgINXdq (ORCPT ); Mon, 14 Sep 2020 19:33:46 -0400 Received: from mail104.syd.optusnet.com.au ([211.29.132.246]:49443 "EHLO mail104.syd.optusnet.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725953AbgINXdp (ORCPT ); Mon, 14 Sep 2020 19:33:45 -0400 Received: from dread.disaster.area (pa49-195-191-192.pa.nsw.optusnet.com.au [49.195.191.192]) by mail104.syd.optusnet.com.au (Postfix) with ESMTPS id D1835827A4A; Tue, 15 Sep 2020 09:33:40 +1000 (AEST) Received: from dave by dread.disaster.area with local (Exim 4.92.3) (envelope-from ) id 1kHxyd-00024T-Mh; Tue, 15 Sep 2020 09:33:39 +1000 Date: Tue, 15 Sep 2020 09:33:39 +1000 From: Dave Chinner To: Eric Sandeen Cc: xfs , Zdenek Kabelac Subject: Re: [PATCH] mkfs.xfs: fix ASSERT on too-small device with stripe geometry Message-ID: <20200914233339.GX12131@dread.disaster.area> References: <20200914221201.GW12131@dread.disaster.area> <48fb5c2a-8db0-3a57-2b0f-0f5f35864e53@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <48fb5c2a-8db0-3a57-2b0f-0f5f35864e53@redhat.com> X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.3 cv=KcmsTjQD c=1 sm=1 tr=0 cx=a_idp_d a=vvDRHhr1aDYKXl+H6jx2TA==:117 a=vvDRHhr1aDYKXl+H6jx2TA==:17 a=kj9zAlcOel0A:10 a=reM5J-MqmosA:10 a=20KFwNOVAAAA:8 a=7-415B0cAAAA:8 a=NqG5SH5wbdJCp-S6ehkA:9 a=CjuIK1q_8ugA:10 a=biEYGPWJfzWAr4FL6Ov7:22 Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Mon, Sep 14, 2020 at 05:29:17PM -0500, Eric Sandeen wrote: > On 9/14/20 5:12 PM, Dave Chinner wrote: > > On Mon, Sep 14, 2020 at 01:26:01PM -0500, Eric Sandeen wrote: > >> When a too-small device is created with stripe geometry, we hit an > >> assert in align_ag_geometry(): > >> > >> # truncate --size=10444800 testfile > >> # mkfs.xfs -dsu=65536,sw=1 testfile > >> mkfs.xfs: xfs_mkfs.c:2834: align_ag_geometry: Assertion `cfg->agcount != 0' failed. > >> > >> This is because align_ag_geometry() finds that the size of the last > >> (only) AG is too small, and attempts to trim it off. Obviously 0 > >> AGs is invalid, and we hit the ASSERT. > >> > >> Fix this by skipping the last-ag-trim if there is only one AG, and > >> add a new test to validate_ag_geometry() which offers a very specific, > >> clear warning if the device (in dblocks) is smaller than the minimum > >> allowed AG size. > >> > >> Reported-by: Zdenek Kabelac > >> Signed-off-by: Eric Sandeen > >> --- > >> > >> diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c > >> index a687f385..da8c5986 100644 > >> --- a/mkfs/xfs_mkfs.c > >> +++ b/mkfs/xfs_mkfs.c > >> @@ -1038,6 +1038,15 @@ validate_ag_geometry( > >> uint64_t agsize, > >> uint64_t agcount) > >> { > >> + /* Is this device simply too small? */ > >> + if (dblocks < XFS_AG_MIN_BLOCKS(blocklog)) { > >> + fprintf(stderr, > >> + _("device (%lld blocks) too small, need at least %lld blocks\n"), > >> + (long long)dblocks, > >> + (long long)XFS_AG_MIN_BLOCKS(blocklog)); > >> + usage(); > >> + } > > > > Ummm, shouldn't this be caught two checks later down by this: > > > > if (agsize > dblocks) { > > fprintf(stderr, > > _("agsize (%lld blocks) too big, data area is %lld blocks\n"), > > (long long)agsize, (long long)dblocks); > > usage(); > > } > > No, because we hit an ASSERT before we ever called this validation > function. Huh, we're supposed to have already validated the data device size is larger than the minimum supported before we try to align the Ag sizes to the data dev geometry. > The error this is trying to fix is essentially: Do not attempt to > trim off the last/only AG in the filesystem. But trimming *should never happen* for single AG filesystems. If we've got dblocks < minimum AG size for a single AG filesystem and we are only discovering that when we are doing AG alignment mods, then we've -failed to bounds check dblocks correctly-. We should have errored out long before we get to aligning AG geometry..... Yup, ok, see validate_datadev(), where we do minimum data subvolume size checks: if (cfg->dblocks < XFS_MIN_DATA_BLOCKS) { fprintf(stderr, _("size %lld of data subvolume is too small, minimum %d blocks\n"), (long long)cfg->dblocks, XFS_MIN_DATA_BLOCKS); usage(); } .... and there's the bug: #define XFS_MIN_DATA_BLOCKS 100 That's wrong and that's the bug here: minimum data device size is 1 whole AG, which means that this should be: #define XFS_MIN_DATA_BLOCKS(cfg) XFS_AG_MIN_BLOCKS((cfg)->blocklog) Cheers, Dave. -- Dave Chinner david@fromorbit.com