From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794445213; b=0TyoqZU8DVg3qawyh98Uee1AVfBQVt51oRY9wtD8lW1pCgvhDX00NYDq0ejFEHDqTJ+A nueXP9X4ZV9raquLP0+DxbF8VKbj59cc0HZ0+wnedMXcbiMLhqnJut+5qZ+SCxJPLCfRm BL1CeexynzLKM7agjv06EFOnGtGFCG1I7ntm1MhUV9ZRD7BBvWpuDzKEJHH8jSVq6NBUH NtcJt7TuxVvxS3XBowL72YOMUXtt1NkXZZc6MreHGTpXOqjjnVXY4ekUfWG8orxQFDnWO PS2Aejx+ObWEwtwwoK7398NUoRSasmfarzzsSpIG/diEuEKOXzVVgpqH/G2C08Y466g== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794445213; h=Received:DKIM-Signature:From:To:Subject:Date:Message-ID:MIME-Version: Content-Type:Content-Transfer-Encoding; bh=zWmPymlzejZ7GlRCAMVbhE088neiMPzQi0kZtOpaw+k=; b=Yi1/cBci8e4P6vkEf7yU0Kxu0DawPfVfkEyYrYY0Wa+Lr1k09iB1J8fOb6dh4PNzruBh UgNjs2bXerb6czbbrK8V0g/DPtEd/KX3vYYibgVfzBbz499cJ4tVbllfNanLpU6xt9lDp OL5VzcG/qr+mPIBGMozPHL/qLiSpbj2C+cQEzUJFce8kE4nJ8MONYIinmP84848e+J7wK nNwgftYJMBH+Nn/y7YGfwZ7NEondutFh5lyVfRUMLmnWgoWvobNeh2Guhz/0OuLoyaR17 SWihuUR+ZtRLqETgkOH51IpR6c/XMOuJVXOEjYmdD7smNBDubjjMfr1Q/G/xUtmWL/Q== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=HoCe7KRc; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 63D6B606A31C; Thu, 12 Nov 2026 01:00:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=HoCe7KRc Received: by smtp.kernel.org (Postfix) with ESMTPSA id A5D531F00A0B; Thu, 12 Nov 2026 01:00:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794445213; bh=zWmPymlzejZ7GlRCAMVbhE088neiMPzQi0kZtOpaw+k=; h=From:To:Subject:Date; b=HoCe7KRcGj8jAFQEs1D9GiRgDXNz3LDhrmUYEPVHbevYH9YfU+FjakM1Rsr/12BVz AKqK8cbxu2GGJ5kdzH+p6x13xmvjaGo3+8Pr9phKSuMlxIyPSbzAsYXZQkuxaBc6U+ nPeHbxqFSzuO3bkQ7ECIdTK4TftHgIxs8aVj6YfNvWuyagEw4+VgYGp0yNKloRqEmI rKJ7F+fwg2MxhrWTACzOgApoYTHrX2ai1U8gAow5nhTZ98g7DV1SOrxjSNDXyuJr2p VcPgPxwKz6hABV+1k17nIP/BNALeMszLG81kLzL1TmSC0vopKb6LgmjjD39tcFXclS iyP/RjZstQBPw== From: Chris Mason To: mason@kernel.org, tytso@mit.edu, cem@kernel.org, david@fromorbit.com, jack@suse.cz, djwong@kernel.org, josef@toxicpanda.com, hch@lst.de, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, tz2294@columbia.edu, brauner@kernel.org Subject: [PATCH v8 00/15] reflink and atomic write bugs Date: Wed, 11 Nov 2026 20:00:10 -0500 Message-ID: <20261112010010.50612-1-mason@kernel.org> X-Mailing-List: linux-xfs@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This series did a few rounds privately, but looks ready for the list now. Carlos has accepted patches 1-4, but I've kept them here so the whole series can still be tested. Except for Christoph's patch, these were all found and fixed by an LLM. The meat of the series is fixing reflink corner cases that incorrectly let you write into the source of a reflink. LLMs also tripped over a few ways to use atomic writes to expose stale blocks on the drive, and a few races with realtime flag and extent size hint manipulations. v7->v8: Christoph pointed out that only page faults can cope with the -EAGAIN from "xfs: restart faults racing with realtime flag changes". pNFS is the one other caller that can really get there, so now faults get -EAGAIN and everyone else gets -EINVAL. Sashiko had two complaints about the same patch. The stale reservation is fixed by the two "resample" patches. Those are the rest of the 3 additional patches I promised in v7, I just managed to leave them out of the posting. The second complaint turned out to be on disk corruption for realtime filesystems with extents bigger than one block, with nothing returning an error. That's the new "xfs: test for an extsize hint again under the ILOCK". While checking what a DAX fault does with the -EAGAIN, we found that DAX and zoned inodes don't work together at all. With a zoned filesystem on pmem and dax=always, the first store into a mapped file oopses on 7.4-rc2, and so does ftruncate(). "xfs: don't enable DAX on zoned inodes" turns DAX off for zoned inodes. Added Christoph's review to "xfs: test for always COW after the dio write checks". v6->v7: Sashiko noticed a few pre-existing corners that I had ignored, so we have 3 additional patches dealing with races between FS_IOC_FSSETXATTR and decisions about file writes. "xfs: restart faults racing with realtime flag changes" changed enough that I dropped Christoph's review. Chris Mason (14): xfs: don't skip the flush before shifting extents xfs: flush the shifted range before changing the file xfs: don't change the block map under a dirty folio iomap: don't punch delalloc under a dirty EOF block fs: validate atomic writes after O_APPEND and limits xfs: recheck direct write alignment after write checks xfs: test for reflink after the dio write checks xfs: test for always COW after the dio write checks xfs: refuse fallocate racing with realtime flag changes xfs: restart faults racing with realtime flag changes xfs: test for an extsize hint again under the ILOCK xfs: resample the extsize hint after taking the ILOCK xfs: resample the COW extsize hint after cycling ILOCK xfs: don't enable DAX on zoned inodes Christoph Hellwig (1): xfs: refuse writes to files racing with realtime inode flag changes fs/ext4/file.c | 4 - fs/iomap/buffered-io.c | 34 ++++++++- fs/read_write.c | 13 ++++ fs/xfs/xfs_bmap_util.c | 19 ++++- fs/xfs/xfs_file.c | 167 ++++++++++++++++++++++++++++++++--------- fs/xfs/xfs_ioctl.c | 8 +- fs/xfs/xfs_iomap.c | 73 ++++++++++++++++-- fs/xfs/xfs_iops.c | 4 + fs/xfs/xfs_reflink.c | 16 +++- 9 files changed, 282 insertions(+), 56 deletions(-)