LLNL has created an standalone ldiskfs package that is maintained outside of the lustre tree. Currently this is maintained at https://github.com/nedbass/lustre-ldiskfs but we will eventually move it to our organization page at https://github.com/chaos. This package makes it easier for us to port lustre to newer kernels, i.e. we don't have to generate a new ldiskfs patch stack for each kernel. Instead we support multiple kernel APIs within ldiskfs with the help of autoconf. We think this approach improves the maintainability and stability of ldiskfs compared to the current practice of copying and patching ext sources from the kernel. Also as Lustre adds support for other backend filesystems like ZFS we should be consistent in how we package them.

This issue is to request review of a patch that adds a configure option --with-ldiskfs-devel to enable the use of this external package. I will push this to gerrit shortly.