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From: Miklos Szeredi <miklos@szeredi.hu>
To: NeilBrown <neilb@suse.de>
Cc: Andy Whitcroft <apw@canonical.com>, viro@ZenIV.linux.org.uk,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        akpm@linux-foundation.org, nbd@openwrt.org, hramrach@centrum.cz,
        jordipujolp@gmail.com
Subject: Re: [PATCH 0/7] overlay filesystem v9
References: <1305635452-14835-1-git-send-email-miklos@szeredi.hu>
	<20110519163709.GH3702@shadowen.org>
	<87sjsak2jt.fsf@tucsk.pomaz.szeredi.hu>
	<20110519180558.GJ3702@shadowen.org>
	<20110520081226.0787e2dd@notabene.brown>
Date: Fri, 20 May 2011 10:18:30 +0200
In-Reply-To: <20110520081226.0787e2dd@notabene.brown> (NeilBrown's message of
	"Fri, 20 May 2011 08:12:26 +1000")
Message-ID: <87ipt5vl7t.fsf@tucsk.pomaz.szeredi.hu>
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(Neil, sorry for the dup)

NeilBrown <neilb@suse.de> writes:

> On Thu, 19 May 2011 19:05:58 +0100 Andy Whitcroft <apw@canonical.com> wrote:
>
>> On Thu, May 19, 2011 at 07:44:54PM +0200, Miklos Szeredi wrote:
>> > I'd be happier if the LSM module were fixed not to peek inside the inode
>> > structure.  Some filesystems (notably network ones) do not guarantee i_*
>> > to be up-to-date, relying on these is not a good idea.
>> 
>> I wonder what what the official way to get ownership information for an
>> inode is if we cannot rely on those.  I am happy to get the Yama LSM
>> fixed up if they are doing something wrong.
>> 
>> -apw
>
> inode->getattr(...., &kstat);
> look at kstat.uid, kstat.gid.

Yeah, it should probably do something like:

	if (inode->i_op->getattr) {
		struct kstat stat;
		inode->i_op->getattr(...)
		uid = stat.uid;
	} else {
		uid = inode->i_uid;
	}

The problem is that getattr takes a vfsmount, which makes this
impossible to do cleanly.  And the solution is for ->getattr() to lose
that argument, which is a bit more involved :(

Thanks,
Miklos
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