From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 03A20394471; Sun, 2 Aug 2026 12:12:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785672767; cv=none; b=ua7Mw9RyQa9XBNulZ1+POocZTrZR/S6GawmCHhAm9/FapX7EejtCPYNFavCRuqlF26rwHsX+WOk1VvXgShAQQehTthHeFDcT4u17SICs0bpeztzX8cMXM3ptLkXp7jeBaLe7PC0BueqPgKg9NkdbkSTXysSUTLy612jpYWUX88M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785672767; c=relaxed/simple; bh=qip+Kprzqn2YKns8DGI0WU7nL6cLJFjUctabAvrwOls=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=jt4CqF/xJHhAxnJmL2WASJhqPi/ijJ1+Cmwt4vUispDKNSMC6Rzl89B48CpclGTb0bdFCqE8pKIn1ciTabxcvjgArKX0vBu10kPYT92EVzAks0dBcgVy8eNm4G45TLsp2NI8cR8b9g57LhSAi+LxeZu64GXkOFeorVVZRHKp9GA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UQgyNJjV; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="UQgyNJjV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CDB081F00A3A; Sun, 2 Aug 2026 12:12:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785672765; bh=C3lCWflyUkl75Hc6AtfOhzt9Nhbp572GU9Gs33TPepM=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=UQgyNJjVst/88Pq9hd7I8Uyy8gND+ZXLHNDC52CMbIlabD30UNUJMfK4lqvngZbHE 8EG9SPHxGjCZIodtUXW/AWYmTYFb2BobR7cpKtgLJEr6SYD4D2corDKI5UfOhjuuC7 CHW75Dr6cuEtDSyZS5PQfo3T+znqRWw1E2SUK68d7n4Or5d0R/aVRZ7QshBbW++p6J pW7J7GukIShjiDRYad9yRWMuCEbmbaYOTo7O6v7CyldE8aL9hXieqxaS7uwEsO9rAl qm86PasyKaoIF3ZMHt8FMXqR//AmKu6ojpOIfNfgHM7XU9Ax504fIojuuUlFJUSY2O +W+2MxQKwJlIQ== Date: Sun, 2 Aug 2026 20:12:38 +0800 From: Zorro Lang To: Lin Jiapeng Cc: hch@lst.de, linux-xfs@vger.kernel.org, fstests@vger.kernel.org, djwong@kernel.org, jiapenglin@tencent.com Subject: Re: [PATCH v2] xfs/842: verify CoW after exchangerange with FILE1_WRITTEN on shared extents Message-ID: Mail-Followup-To: Lin Jiapeng , hch@lst.de, linux-xfs@vger.kernel.org, fstests@vger.kernel.org, djwong@kernel.org, jiapenglin@tencent.com References: <20260729025504.54586-1-jiapenglin@tencent.com> Precedence: bulk X-Mailing-List: linux-xfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260729025504.54586-1-jiapenglin@tencent.com> On Wed, Jul 29, 2026 at 10:54:54AM +0800, Lin Jiapeng wrote: > When a full-file exchangerange is requested with FILE1_WRITTEN for a > fully sparse donor file, every mapping pair is skipped, so no extents > actually move. However, the kernel decides to swap the reflink inode > flag based on the request geometry alone, so the target file used to > lose its reflink flag to the donor while still owning shared extents. > A subsequent write then took the non-reflink write path and modified > the shared physical blocks in place, silently corrupting the other > file sharing them: > > --- tests/xfs/842.out > +++ results/xfs/842.out.bad > @@ -1,4 +1,5 @@ > QA output created by 842 > +vX.reflink = 0 > vX.reflink = 1 > -vX.reflink = 1 > +orig changed: md5 e6065c4aa2ab1603008fc18410f579d4 -> 32c5189478e6bafa1cc76423f06c88f2 (write hit shared blocks in place) > Silence is golden > > This test clones a file so that both share extents, swaps the clone > against a sparse donor with FILE1_WRITTEN, and then checks the defect > twice. First it inspects the inodes directly with xfs_db: the clone > must still be flagged reflink after the exchange (the donor carrying > the flag too is the conservative outcome of the fix and is harmless). > Then it writes to the clone and verifies after a mount cycle that the > original file's data is intact, i.e. the write was redirected through > CoW. > > The kernel fix "xfs: fix exchange-range reflink flag clearing issue > with INO1_WRITTEN" refuses the reflink flag exchange whenever So this patch/case uncovers a known bug which is fixed by: "xfs: fix exchange-range reflink flag clearing issue with INO1_WRITTEN" ? If so please add: _fixed_by_fs_commit xfs xxxxxxxxxxxx \ "xfs: fix exchange-range reflink flag clearing issue with INO1_WRITTEN" > FILE1_WRITTEN is requested, which makes this test pass. > > Reported-by: Lin Jiapeng(TencentOS Red Team) > Link: https://lore.kernel.org/r/amgekiNKKoAdACnc@infradead.org > Suggested-by: Christoph Hellwig > Suggested-by: "Darrick J. Wong" > Reviewed-by: "Darrick J. Wong" > Signed-off-by: Lin Jiapeng > --- > tests/xfs/842 | 65 +++++++++++++++++++++++++++++++++++++++++++++++ > tests/xfs/842.out | 4 +++ > 2 files changed, 69 insertions(+) > create mode 100755 tests/xfs/842 > create mode 100644 tests/xfs/842.out > > diff --git a/tests/xfs/842 b/tests/xfs/842 > new file mode 100755 > index 0000000..c4c2be9 > --- /dev/null > +++ b/tests/xfs/842 > @@ -0,0 +1,65 @@ > +#! /bin/bash > +# SPDX-License-Identifier: GPL-2.0-or-later > +# Copyright (c) 2026 Tencent. All Rights Reserved. > +# > +# FS QA Test No. 842 > +# > +# Make sure that a full-file exchangerange under FILE1_WRITTEN does not strip > +# the reflink flag from a file that still owns shared extents. When the > +# donor file is fully sparse, every mapping pair is skipped, so no extents > +# actually move; the target file must keep its reflink flag, and a later > +# write must go through CoW instead of modifying the shared blocks in place. > + > +. ./common/preamble > +_begin_fstest auto quick fiexchange > + > +# Import common functions. > +. ./common/filter > +. ./common/reflink > + > +_require_xfs_io_command exchangerange > +_require_scratch_reflink > +_require_scratch _require_scratch_reflink contains _require_scratch, so you can save the _require_scratch. > + > +_scratch_mkfs >> $seqres.full > +_scratch_mount > + > +# Create the original file with a known pattern and clone it, so that both > +# files share the same extents. > +_pwrite_byte 0x41 0 1m $SCRATCH_MNT/orig >> $seqres.full > +_reflink $SCRATCH_MNT/orig $SCRATCH_MNT/clone >> $seqres.full > + > +# Create a fully sparse donor file of the same size. > +$XFS_IO_PROG -f -c 'truncate 1m' $SCRATCH_MNT/donor > + > +md5_before=$(md5sum $SCRATCH_MNT/orig | awk '{print $1}') > + > +# Swap the clone against the sparse donor, claiming the donor is fully > +# written (-w). Every donor mapping is a hole, so all pairs are skipped > +# and the clone keeps its shared extents in place. > +$XFS_IO_PROG -c "exchangerange -f -w $SCRATCH_MNT/donor" $SCRATCH_MNT/clone \ > + >> $seqres.full > + > +# Directly confirm the inode flag state after the exchange: the clone > +# must still be flagged reflink. The donor may also carry the flag, which > +# is the conservative outcome of refusing the flag exchange under > +# FILE1_WRITTEN; the extra flag is harmless and can be dropped later by > +# the regular reflink flag cleanup path. > +_scratch_unmount > +_scratch_xfs_db -c "path /clone" -c print -c "path /donor" -c print | \ > + grep reflink | sed -e 's/^v[0-9]*/vX/g' > +_scratch_mount > + > +# Overwrite part of the clone. With the reflink flag correctly retained, > +# this must go through CoW and leave the shared blocks of orig untouched. > +_pwrite_byte 0x42 0 64k $SCRATCH_MNT/clone >> $seqres.full > +_scratch_cycle_mount > + > +md5_after=$(md5sum $SCRATCH_MNT/orig | awk '{print $1}') > + > +test "$md5_before" != "$md5_after" && \ > + echo "orig changed: md5 $md5_before -> $md5_after (write hit shared blocks in place)" > + > +echo Silence is golden This case has expected output, so it's not "Silence is golden", please remove this line. > +status=0 > +exit I remember we've changed xfstests/new script, it should give "_exit 0" at here. Thanks, Zorro > diff --git a/tests/xfs/842.out b/tests/xfs/842.out > new file mode 100644 > index 0000000..1e6345a > --- /dev/null > +++ b/tests/xfs/842.out > @@ -0,0 +1,4 @@ > +QA output created by 842 > +vX.reflink = 1 > +vX.reflink = 1 > +Silence is golden > -- > 2.50.1 (Apple Git-155) >