linux-kernel - Re: [PATCH -V8 00/26] New ACL format for better NFSv4 acl interoperability

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Date:	Mon, 24 Oct 2011 07:07:59 -0400
From:	"J. Bruce Fields" <bfields@...ldses.org>
To:	Christoph Hellwig <hch@...radead.org>
Cc:	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
	agruen@...nel.org, akpm@...ux-foundation.org,
	viro@...iv.linux.org.uk, dhowells@...hat.com,
	linux-fsdevel@...r.kernel.org, linux-nfs@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH -V8 00/26]  New ACL format for better NFSv4 acl
 interoperability

On Mon, Oct 24, 2011 at 05:49:10AM -0400, Christoph Hellwig wrote:
> On Mon, Oct 24, 2011 at 05:17:16AM -0400, J. Bruce Fields wrote:
> > > How do we push these changes to Linus tree ? Andrew, Viro, any comment
> > > on how we can get this merged upstream ?
> > 
> > Andrew, it sounds like you might be willing to shepherd these through?
> > Let us know what you'd need.
> 
> It really has to through the VFS tree.

Do we have a VFS tree right now?

> And to be honest despite the repostings there's been exactly zero
> progress on getting there.

Apparently some review was missed--do you have pointers to it, if
there's anything that isn't covered below?

> Please as a first thing submit the various small cleanups indepent
> of the other changes.  If you can't even those in there's no point
> in trying.  Second do not repeat the mistakes of the old ACL code,
> that is don't do too much work inside the filesystems.  Al, Linus
> and me spent a lot of working on pushing it into common code and
> it's not done.  For any new ACL model I really want to see zero
> per-fs code except for callouts in chmod & co and actually
> setting the xattr vector to a genericly provided one.  And please
> wire up all common filesystems to actually prove that point.

Sounds reasonable.

> I also really hate all the duplication - I want to see a really good
> reason why all this code needs to be duplicated.  Just look at
> the mess done to check_acl and the ACL caching in the inode and
> any normal person would throw up.  There is absolutely no reason
> to not implement Posix ACLs as a subset of the NFSv4 ACL (not actually
> a subset in the strict mathematical sense, but close enough).

Just to make sure I understand: you're just talking about the
implementation here--you want as much as possible to be done by routines
shared by NFSv4 and Posix ACLs--right?  (You're not suggesting that e.g.
a user should be able to treat NFSv4 ACLs as if they were Posix ACLs.)

> After all this techical work (which was brought up before) has been
> done you can resubmit it.  And that point you'd better have very
> good and very lengthy rationale for why adding an utterly stupid
> ACL model is supposed to be a good idea.

It's the ACL model that Samba and NFSv4 clients use, and we want to do a
better job of exporting linux filesystems to those clients.

I don't know how to make the justification much longer than that.

--b.
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