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From: Neil Brown <neilb@cse.unsw.edu.au>
To: Alexander Viro <viro@math.psu.edu>
Date: Mon, 19 Nov 2001 15:02:40 +1100 (EST)
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Message-ID: <15352.33888.506871.191768@notabene.cse.unsw.edu.au>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Devlinks.  Code.  (Dcache abuse?)
In-Reply-To: message from Alexander Viro on Friday November 16
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On Friday November 16, viro@math.psu.edu wrote:
> 
> 
> On Fri, 16 Nov 2001, Neil Brown wrote:
> 
> > +	if (!(nd->mnt->mnt_flags & MNT_NODEV)
> > +	    && dentry->d_inode
> > +	    && (dentry->d_inode->i_mode & S_ISVTX)) {
> > +		dentry = devlink_find(dentry, link);
> 
> You are breaking vfsmount refcounting.  Badly.

I looked, and I cannot see it.
I never change the refcound on any vfsmount, nor to I make
or destroy any references to any vfsmount.
In this piece of code we don't even own a reference to "dentry" (the
caller does) so assigning over it isn't a problem either.

About the only thing that might be a bit odd here is that we change
nd->dentry a few lines later without changing nd->mnt.  But the new
dentry is always in the same dentry tree (though it is in owned
by a different filesystem).

Would you care to give a few more details?

NeilBrown
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