Fix errval variable to be positive errno value

The local variable errval is used for strerror(3) which only works
with positive values (i.e. -EXXX doesn't return an expected string).

Signed-off-by: Tomohiro Kusumi <tkusumi@tuxera.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
1 file changed