tree ed5a796823ccb7e039b209d7e88a550d3fd74e8f
parent b23df0d048e5f137ad5c2a116ec0849a98d43b96
author Bart Van Assche <bart.vanassche@sandisk.com> 1479508080 -0800
committer Mike Snitzer <snitzer@redhat.com> 1481224388 -0500

dm ioctl: use offsetof() instead of open-coding it

Subtracting sizes is a fragile approach because the result is only
correct if the compiler has not added any padding at the end of the
structure. Hence use offsetof() instead of size subtraction. An
additional advantage of offsetof() is that it makes the intent more
clear.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>