[PATCH 1/2] zhashfs, detect fill pattern and suppress blocks in output

[Daniel Drake]

On 21 April 2011 05:46, James Cameron <quozl at laptop.org> wrote:
> Allows the unused filesystem blocks of the image to be left out of the
> .zd file, resulting in a factor of two reduction in fs-update times on
> a typical build on a 4GB microSD.  Greater reduction occurs on larger
> microSD or SD cards.
>
> Has no effect if a fill pattern file is not found.

A more correct option would be to use the FIEMAP ioctl to detect the
gaps in the file and determine the unused blocks that way. Have you
investigated this?

Daniel