[PATCH] fix xip sparse file handling in ext2

Oliver Paukstadt from our test department is testing the xip patches in
Linus' git-tree.  He found a problem that shows when reading a file that
contains sparse blocks (holes) on a -o xip mounted ext2 filesystem: the
BUG_ON() in fs/ext2/xip.c:40 triggers where it should not.  The problem was
introduced by a cleanup in my previous patch, this patch fixes it.

Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>