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. -- Kevin Corry kevcorry@xxxxxxxxxx http://www.ibm.com/linux/ http://evms.sourceforge.net/ The size of a stripe device must be a multiple of its chunk-size. Signed-off-by: Kevin Corry <kevcorry@xxxxxxxxxx> dm-stripe.c | 6 ++++++ 1 file changed, 6 insertions(+) --- diff/drivers/md/dm-stripe.c 2006-03-14 15:57:30.000000000 -0600 +++ source/drivers/md/dm-stripe.c 2006-03-14 16:01:41.000000000 -0600 @@ -103,6 +103,12 @@ return -EINVAL; } + if (((uint32_t)ti->len) & (chunk_size - 1)) { + ti->error = "dm-stripe: Target length not divisable by " + "chunk size"; + return -EINVAL; + } + width = ti->len; if (sector_div(width, stripes)) { ti->error = "dm-stripe: Target length not divisable by " -- dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
