For the purpose of image construction using du on a rootfs directory isn't
entirely satisfactory. Bare "du" will report the actual disk usage so file
systems which can compress the data will report less than the actual space
required. Using "du --apparent-size" will report the actual space used, but as
this simply sums the bytes used for content across an entire file system can
result in significant under-reporting due to block size overhead.
Attempt to solve these problems by implementing our own function to calculate
how large a rootfs will be. This function handles hardlinks correctly but
rounds up all sizes to multiples of the block size (currently, 4KB is the
hard-coded block size).
Signed-off-by: Ross Burton <ross.burton@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
