Recompile kernel after editing some code
 

I have compiled the kernel fine. Works ok but I have now edited a source file fs/ext3/file.c and I cannot get that file to be recompiled. I have tried many variations of make-kpkg but nothing seems to compile that file. I used apt-get to get the source and followed these instructions (old method) for building initially.
https://help.ubuntu.com/community/Kernel/Compile
Any idea how to get this edited file built? Thanks.

I know there are utilities for applying patches to source code, one of them is called 'patch'. That is the first thing I would try, you should get the original file and edit a copy of it then use the patch tool to apply the changes.

Thanks. I'd have thought that some variation of make-kpkg would work - or maybe the make rules are broken. I have recompiled the whole lot to get my small change recognised for now.