From: Oleg Drokin <green@namesys.com>

This patch allows reiserfs to support blocksizes from 1024 bytes and up to
PAGE_CACHE_SIZE.  Also it fixes two glitches that prevent reiserfs from
working correctly in case if PAGE_CACHE_SIZE is bigger than blocksize.

Originally this patch was created by Edward Shushkin and Vladimir Saveliev,
and then it was adapted to modern 2.4 and 2.5 by me.

Also people should be aware that 1024 bytes blocksize is not very good thing
as tree grows very fast.  mkreiserfs is able to create filesystems with
different blocksizes for quite a while already (-b switch).