If we punch a hole on a reflink such that following conditions are met:
1. start offset is on a cluster boundary
2. end offset is not on a cluster boundary
3. (end offset is somewhere in another extent) or
(hole range > MAX_CONTIG_BYTES(1MB)),
we dont COW the first cluster starting at the start offset. But in this
case, we were wrongly passing this cluster to
ocfs2_zero_range_for_truncate() to zero out. This will modify the
cluster in place and zero it in the source too.
Fix this by skipping this cluster in such a scenario.
To reproduce:
1. Create a random file of say 10 MB
xfs_io -c 'pwrite -b 4k 0 10M' -f 10MBfile
2. Reflink it
reflink -f 10MBfile reflnktest
3. Punch a hole at starting at cluster boundary with range greater that
1MB. You can also use a range that will put the end offset in another
extent.
fallocate -p -o 0 -l 1048615 reflnktest
4. sync
5. Check the first cluster in the source file. (It will be zeroed out).
dd if=10MBfile iflag=direct bs=<cluster size> count=1 | hexdump -C
Link: http://lkml.kernel.org/r/1470957147-14185-1-git-send-email-ashish.samant@oracle.com
Signed-off-by: Ashish Samant <ashish.samant@oracle.com>
Reported-by: Saar Maoz <saar.maoz@oracle.com>
Reviewed-by: Srinivas Eeda <srinivas.eeda@oracle.com>
Cc: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Joseph Qi <joseph.qi@huawei.com>
Cc: Eric Ren <zren@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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