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The dm-stripe target currently does not enforce that the size of a stripe
device be a multiple of the chunk-size. Under certain conditions, this can
lead to I/O requests going off the end of an underlying device. This
test-case shows one example.
echo "0 100 linear /dev/hdb1 0" | dmsetup create linear0
echo "0 100 linear /dev/hdb1 100" | dmsetup create linear1
echo "0 200 striped 2 32 /dev/mapper/linear0 0 /dev/mapper/linear1 0" | \
dmsetup create stripe0
dd if=/dev/zero of=/dev/mapper/stripe0 bs=1k
This will produce the output:
dd: writing '/dev/mapper/stripe0': Input/output error
97+0 records in
96+0 records out
And in the kernel log will be:
attempt to access beyond end of device
dm-0: rw=0, want=104, limit=100
The patch will check that the table size is a multiple of the stripe
chunk-size when the table is created, which will prevent the above striped
device from being created.
This should not affect tools like LVM or EVMS, since in all the cases I can
think of, striped devices are always created with the sizes being a
multiple of the chunk-size.
The size of a stripe device must be a multiple of its chunk-size.
(akpm: that typecast is quite gratuitous)
Signed-off-by: Kevin Corry <kevcorry@us.ibm.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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