Re: [RFC PATCH] cogito --- don't overwrite metadata files in place (breaks CoW use)

From: Linus Torvalds <torvalds@osdl.org>
Date: Jul 13, 2005, 20:05 UTC
Message-ID: <Pine.LNX.4.58.0507131256490.17536@g5.osdl.org>
In-Reply-To: <20050713185339.GA9260@taniwha.stupidest.org>

On Wed, 13 Jul 2005, Chris Wedgwood wrote:

Show 8 quoted lines

> On Wed, Jul 13, 2005 at 09:03:26AM +0200, Matthias Urlichs wrote:
> 
> > You are ;-) the tree itsels is no symlinked, but HEAD points to
> > refs/heads/<branch> by default.
> 
> Thanks for pointing that out.  I honestly never noticed that.
> 
> How about the following?

This is really complicated, for no good reason.

The _object_ directories should be linked, but it's really wrong to link the "refs/" directories and expect them to have COW behaviour.

I've tried to make most of the git tools write the refs objects "safely" too, ie things like "git-receive-pack" (the receiving end of a "git-send-pack") will write the new ref to a lock-file and then do a "rename()" to set it. That is COW-safe, but the thing is, it's incredibly painful for many other operations, and I won't guarantee that git in general is always going to be COW-safe wrt all the git files.

For example, the "git clone -l" behaviour will _only_ link the objects subdirectory. The rest is copied. Unless there's a bug there somewhere.

		Linus