linux-kernel - Re: NFS client broken in Linus' tip

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Message-Id: <3003D7E5-93F8-4B32-ACDB-07ED3F6CE70D@primarydata.com>
Date:	Mon, 3 Feb 2014 10:45:48 -0500
From:	Trond Myklebust <trond.myklebust@...marydata.com>
To:	Christoph Hellwig <hch@...radead.org>
Cc:	Russell King - ARM Linux <linux@....linux.org.uk>,
	linuxnfs <linux-nfs@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Viro Alexander <viro@...iv.linux.org.uk>,
	Christoph Hellwig <hch@....de>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: NFS client broken in Linus' tip


On Feb 3, 2014, at 9:57, Christoph Hellwig <hch@...radead.org> wrote:

> On Mon, Feb 03, 2014 at 09:17:30AM -0500, Trond Myklebust wrote:
>> As I said above, that causes posix_acl_xattr_get() to return the wrong answer (ENODATA instead of EOPNOTSUPP).
> 
> Is it really the wrong answer?  How does userspace care wether this
> server doesn't support ACLs at all or none is set?  The resulting
> behavior is the same.

It will certainly cause acl_get_file() to behave differently than previously. I’ve no idea how that will affect applications, though.

> If there's a good reason to care we might have to go with your patch,
> but if we can avoid it I'd prefer to keep things simple.

One alternative is to simply wrap posix_acl_xattr_get() in fs/nfs/nfs3acl.c, and have it check the value of nfs_server_capable(inode, NFS_CAP_ACLS) before returning ENODATA. That’s rather ugly too...

--
Trond Myklebust
Linux NFS client maintainer

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