On 10/2/20 8:07 AM, Sasha Levin wrote:
> 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.
Thansk Sasha - the reviews/acks were given for V1 (hch & darrick), V2 adds them to the
commit log (see above) and fixes a typo in the subject.
Thanks,
-Eric
