[lustre-devel] [LSF/MM/BPF TOPIC] [DRAFT] Lustre client upstreaming

[Day, Timothy]

> This will definitely need some reorganization of files and directories in the
> Lustre source tree to align with the Linux kernel (e.g. moving everything
> under fs/lustre and net/lnet).

I think the Lustre tree ought to have a clearer separation between the
kernel code and user space. It should be pretty easy to shuffle the
directory structure to achieve this. We'd have something like:

fs/lustre/
net/lnet/lnet/
net/lnet/libcfs/
lustre_compat/ <- This gets compiled into libcfs
tests/
utils/

And eventually the fs/ and net/ would live in Linux mainline.
lustre_compat/ would remain to allow us to compile mainline
clients for older kernel, similar to AMDGPU (that I mentioned in
the other thread).

Another benefit of a cleaner split between kernel and user space:
older version of Lustre could definitely benefit from newer user space
features. Patrick's parallel migrate work comes to mind.

> That would probably be a question to get answered, whether LNet is
> "too Lustre specific" to be in net/ and should live in the Lustre tree?
>
> That would make it harder to backport patches to maintenance releases,
> but I'm hoping a script to rework pathnames in patches would be enough.

Newer versions of git are pretty good at finding directories after a relocation.
For example, if you pull down the upstream client branch and Lustre master
into the same repo, you can git cherry-pick a patch from one to the other and it
will automatically find the directories that contains the changed files. This
works even though the two repos don't share a common history.

If I created a patch to reorg Lustre, we could easily test some cherry-picks to
make sure they work right.

Tim Day