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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 50120C433EF for ; Mon, 27 Jun 2022 05:16:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229753AbiF0FQy (ORCPT ); Mon, 27 Jun 2022 01:16:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49836 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229623AbiF0FQx (ORCPT ); Mon, 27 Jun 2022 01:16:53 -0400 Received: from mail105.syd.optusnet.com.au (mail105.syd.optusnet.com.au [211.29.132.249]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id B98AE558E for ; Sun, 26 Jun 2022 22:16:51 -0700 (PDT) Received: from dread.disaster.area (pa49-181-2-147.pa.nsw.optusnet.com.au [49.181.2.147]) by mail105.syd.optusnet.com.au (Postfix) with ESMTPS id ED7C510E77E0; Mon, 27 Jun 2022 15:16:50 +1000 (AEST) Received: from dave by dread.disaster.area with local (Exim 4.92.3) (envelope-from ) id 1o5h7B-00BYaB-TB; Mon, 27 Jun 2022 15:16:49 +1000 Date: Mon, 27 Jun 2022 15:16:49 +1000 From: Dave Chinner To: "Darrick J. Wong" Cc: linux-xfs@vger.kernel.org, allison.henderson@oracle.com Subject: Re: [PATCH 3/3] xfs: dont treat rt extents beyond EOF as eofblocks to be cleared Message-ID: <20220627051649.GD227878@dread.disaster.area> References: <165628102728.4040423.16023948770805941408.stgit@magnolia> <165628104422.4040423.6482533913763183686.stgit@magnolia> <20220627013731.GB227878@dread.disaster.area> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.4 cv=e9dl9Yl/ c=1 sm=1 tr=0 ts=62b93d43 a=ivVLWpVy4j68lT4lJFbQgw==:117 a=ivVLWpVy4j68lT4lJFbQgw==:17 a=kj9zAlcOel0A:10 a=JPEYwPQDsx4A:10 a=VwQbUJbxAAAA:8 a=20KFwNOVAAAA:8 a=7-415B0cAAAA:8 a=WK67UY_BvgFgf0169DQA:9 a=CjuIK1q_8ugA:10 a=AjGcO6oz07-iQ99wixmX:22 a=biEYGPWJfzWAr4FL6Ov7:22 Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Sun, Jun 26, 2022 at 08:57:25PM -0700, Darrick J. Wong wrote: > On Mon, Jun 27, 2022 at 11:37:31AM +1000, Dave Chinner wrote: > > On Sun, Jun 26, 2022 at 03:04:04PM -0700, Darrick J. Wong wrote: > > > From: Darrick J. Wong > > > > > > On a system with a realtime volume and a 28k realtime extent, > > > generic/491 fails because the test opens a file on a frozen filesystem > > > and closing it causes xfs_release -> xfs_can_free_eofblocks to > > > mistakenly think that the the blocks of the realtime extent beyond EOF > > > are posteof blocks to be freed. Realtime extents cannot be partially > > > unmapped, so this is pointless. Worse yet, this triggers posteof > > > cleanup, which stalls on a transaction allocation, which is why the test > > > fails. > > > > > > Teach the predicate to account for realtime extents properly. > > > > > > Signed-off-by: Darrick J. Wong > > > --- > > > fs/xfs/xfs_bmap_util.c | 2 ++ > > > 1 file changed, 2 insertions(+) > > > > > > > > > diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c > > > index 52be58372c63..85e1a26c92e8 100644 > > > --- a/fs/xfs/xfs_bmap_util.c > > > +++ b/fs/xfs/xfs_bmap_util.c > > > @@ -686,6 +686,8 @@ xfs_can_free_eofblocks( > > > * forever. > > > */ > > > end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)XFS_ISIZE(ip)); > > > + if (XFS_IS_REALTIME_INODE(ip) && mp->m_sb.sb_rextsize > 1) > > > + end_fsb = roundup_64(end_fsb, mp->m_sb.sb_rextsize); > > > last_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes); > > > if (last_fsb <= end_fsb) > > > return false; > > > > Ok, that works. Reviewed-by: Dave Chinner > > > > However, I was looking at xfs_can_free_eofblocks() w.r.t. freeze a > > couple of days ago and wondering why there isn't a freeze/RO state > > check in xfs_can_free_eofblocks(). Shouldn't we have one here so > > that we never try to run xfs_free_eofblocks() on RO/frozen > > filesystems regardless of unexpected state/alignment issues? > > I asked myself that question too. I found three callers of this > predicate: > > 1. fallocate, which should have obtained freeze protection *nod* > 2. inodegc, which should never be running when we get to the innermost > freeze protection level So inodegc could still do IO here on a read-only fs? > 3. xfs_release, which doesn't take freeze protection at all. Either it > needs to take freeze protection so that xfs_free_eofblocks can't get > stuck in xfs_trans_alloc, or we'd need to modify xfs_trans_alloc to > sb_start_intwrite_trylock That looks to me like it is simply a case of replacing the !xfs_is_readonly() check in xfs_release() with a !xfs_fs_writeable(mp, SB_FREEZE_WRITE) check and we shouldn't have to touch anythign else, right? Cheers, Dave. -- Dave Chinner david@fromorbit.com