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Re: [dm-devel] [PATCH] dm-striped device sizes must be multiple of chunk-size

Also, those error messages should read "Target length not divisible...",
not "divisable".


On Tue, 2006-03-14 at 16:31 -0600, Kevin Corry wrote:
> The dm-striped 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 below 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 effect 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.

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