Re: [RFC/PATCH 1/1] format-patch: add an option to record base tree info

From: Eric W. Biederman <ebiederm@xmission.com>
Date: Feb 23, 2016, 19:56 UTC
Message-ID: <87r3g3jj54.fsf@x220.int.ebiederm.org>
In-Reply-To: <20160223091740.GA3830@wfg-t540p.sh.intel.com>

Fengguag Wu, Xiaolong Ye, have you attempted to use the truncated sha1 of the file the patch applies to? Git already places a file sha1 at the top of a patch. See the index line?

> diff --git a/fs/namespace.c b/fs/namespace.c
> index eccd925c6e82..3c3f8172c734 100644
> --- a/fs/namespace.c
> +++ b/fs/namespace.c

As I understand it you are aiming for making a good guess what the patch or patches apply to, having a set of file hashes looks like it would give you that.

All it should take is to iterate over a patchset and for each file in the patchset capture the first file hash. Then in the smallish set of maintainer trees see if that set of file hashes matches any of their recent commits. You should be able to prune the set of possible maintainer trees even more by looking at the mailling list or lists the patch was submitted to.

Before we talk about adding anything more I think we need a clear picture of what you have tried with what already exists. A decade ago part of the problem was that not everyone used git. At best it will take a little while before everyone upgrades to a version of git diff containing your changes, and if possibly even longer if they have to start specifying an additional option when a diff is generated.

Eric