[LTP] [PATCH] mkswap: make the test device size is aligned to pagesize

Li Wang
2016-08-17T03:39:46Z

On Tue, Aug 16, 2016 at 02:15:52PM +0200, Cyril Hrubis wrote:
> Hi!
> > Sorry for the vague description. To be honest, mkswap.c(util-linux) is innocent
> > here. The error maker is mkswap_verify() in mkswap01.sh(ltp) testcase.
> >
> > The key point of problem is not only mkswap01.sh (ltp) doesn't guarantee
> > test-device(LTP_DEV) size is aligned to PAGE_SIZE on all arches, but also
> > it increse/decrease test-device size not aligned too.
> >
> > # tail -15 mkswap01.sh
> > mkswap_test "" "" "$TST_DEVICE"
> > mkswap_test "" "" "$TST_DEVICE" "$((DEVICE_SIZE-10000))" <---
> > mkswap_test "-f" "" "$TST_DEVICE" "$((DEVICE_SIZE+10000))" <---
> > ...
> >
> >
> > As we know that mkswap.c(util-linux) format test-device to aligned with its local
> > PAGE_SIZE by force. Therefore, the real 'filesize' of formated test-device will
> > be decreased in that phase. But final, the testcase just compare orignal 'filesize'
> > to 'diff'(swaptotal-after - swaptotal-before) and make conclusion to get PASS/FAIL.
> > That makes this test result is not reliable.
>
> Now that makes sense.
>
> But if that is the case we still have to align down the device size to
> the page size at the start of the test. Since the device can also be
> passed down to the runltp script as a parameter and we cannot make any
> assumptions about its size.

Hmm, yes, we have to face the problem.

A simple idea comes to my mind is that the loop device size should be
customized by specific testcase(mkswap01.sh).

That would be happy if function "tst_acquire_device() 'NUM'" can get
'NUM' MB block device for testing.

It means we have to modify another path which about tst_acquire_device().

What do you think? any proposals?

-----------
tst_acquire_device()
{
local acq_dev_size=${1}

if [ -z ${TST_TMPDIR} ]; then
tst_brkm "Use 'tst_tmpdir' before 'tst_acquire_device'"
fi

if [ -n "${LTP_DEV}" ] && [ ! ${acq_dev_size} ]; then
tst_resm TINFO "Using test device
LTP_DEV='${LTP_DEV}'"
if [ ! -b ${LTP_DEV} ]; then
tst_brkm TBROK "${LTP_DEV} is not a block device"
fi

ROD_SILENT dd if=/dev/zero of="${LTP_DEV}" bs=1024 count=512 TST_DEVICE=${LTP_DEV}
TST_DEVICE_FLAG=0
return
fi

if [ ! ${acq_dev_size} ]; then
ROD_SILENT dd if=/dev/zero of=test_dev.img bs=1024 count=153600
else
ROD_SILENT dd if=/dev/zero of=test_dev.img bs=1024 count=$((1024*$acq_dev_size))
fi

TST_DEVICE=$(losetup -f)
if [ $? -ne 0 ]; then
tst_brkm TBROK "Couldn't find free loop device"
fi

tst_resm TINFO "Found free device '${TST_DEVICE}'"

ROD_SILENT losetup ${TST_DEVICE} test_dev.img

TST_DEVICE_FLAG=1
}

Regards,
Li Wang