Re: [PATCH v3] xfs: Add test for CVE-2017-14340

[Christoph Hellwig <hch@infradead.org>]

> +_require_xfs_io_command "chattr"
> +_require_xfs_io_command "fsync"
> +_require_xfs_io_command "pwrite"

I think we expect these always to be there in general.  But then
again these checks won't hurt either.

> +_require_test

I can't see the test using the test device, so this should not be
needed.

> +# Set realtime inherit flag on scratch mount, suppress output
> +# as this may simply error out on future kernels, we will check
> +# exit code instead.
> +$XFS_IO_PROG -c 'chattr +t' $SCRATCH_MNT &> /dev/null
> +chattr_ret=$?
> +
> +# Erroring out here is fine, this would be desired behavior for
> +# FSes without realtime devices present.
> +if (( chattr_ret == 0)); then

Don't want to be nitpicky, but the way we usuall write this would be:

$XFS_IO_PROG -c 'chattr +t' $SCRATCH_MNT &> /dev/null

if [ $? -eq 0 ]; then

> +rm -f $SCRATCH_MNT/testfile

We probably don't need to beother with this, as the scratch device
gets reinitialized on every test that uses it.

Otherwise the test looks great, thanks a lot!

Reviewed-by: Christoph Hellwig <hch@lst.de>