On Thu, Oct 01, 2020 at 08:34:48AM -0500, Eric Sandeen wrote:
A bug existed in the XFS reflink code between v5.1 and v5.5 in which
the mapping for a COW IO was not trimmed to the mapping of the COW
extent that was found. This resulted in a too-short copy, and
corruption of other files which shared the original extent.
(This happened only when extent size hints were set, which bypasses
delalloc and led to this code path.)
This was (inadvertently) fixed upstream with
36adcbace24e "xfs: fill out the srcmap in iomap_begin"
and related patches which moved lots of this functionality to
the iomap subsystem.
Hence, this is a -stable only patch, targeted to fix this
corruption vector without other major code changes.
Fixes: 78f0cc9d55cb ("xfs: don't use delalloc extents for COW on files with extsize hints")
Cc: <stable@xxxxxxxxxxxxxxx> # 5.4.x
Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
---
V2: Fix typo in subject, add reviewers
I've tested this with a targeted reproducer (in next email) as well as
with xfstests.
There is also now a testcase for xfstests submitted upstream
Stable folk, not sure how to send a "stable only" patch, or if that's even
valid. Assuming you're willing to accept it, I would still like to have
some formal Reviewed-by's from the xfs developer community before it gets
merged.
This is perfect stable-process-wise :) Will wait for reviews/acks before
merging.
--
Thanks,
Sasha
