Automate OpenZFS patch porting

[dinatale2]

We recently discovered that it is possible to cherry-pick patches directly from the OpenZFS tree. Git will automatically attempt to find the right file to apply a hunk to if it is given enough time to process a change.

To allow git the time to search, you need the following in your git config

[merge]
    renameLimit = 999999

Now, in order to cherry-pick, clone your fork of zfs and add both zfsonlinux/zfs and openzfs/openzfs as remotes. Perform a git fetch --all. Now you can perform a git cherry-pick <OpenZFS commit> to port patches to ZoL.

It would be nice to have a script that would attempt to perform the above process automatically given an OpenZFS commit.

[dinatale2]

@gmelikov you might be interested in this

[gmelikov]

Thanks, i thought about that scenario too. I'll try to make a script for it.

[gmelikov]

@dinatale2 thanks for initial method!
I alreadt made a prototype, it works smoothly. I'll make a PR after massive test.

[gmelikov]

Most of my last PRs are made by script, but unfourtunately these are all that can be merged automatically for now.

One major problem - new files merge with OpenZFS file structure, example - gmelikov/zfs@df3e48b

I'll beautify the script and make a PR later.

[dinatale2]

This was taken care of in #51. Thanks @gmelikov!