Date: Wed, 6 Aug 2003 01:14:49 +0200
From: Herbert =?iso-8859-1?Q?P=F6tzl?= <herbert@13thfloor.at>
To: viro@parcelfarce.linux.theplanet.co.uk
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: RO --bind mount implementation ...
Message-ID: <20030805231449.GD2594@www.13thfloor.at>
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On Wed, Aug 06, 2003 at 12:51:49AM +0200, Herbert P?tzl wrote:
> On Tue, Aug 05, 2003 at 05:59:24PM +0100, viro@parcelfarce.linux.theplanet.co.uk wrote:
> > On Tue, Aug 05, 2003 at 12:16:15AM +0200, Herbert P?tzl wrote:
> >  
> > > anyway, I discussed this with some friends, and
> > > they pointed out that this would be useful ...
> > > so here is the first try ...
> > 
> > Umm...  You know, the most obvious system call that should care about
> > read-only is open(pathname, O_RDWR) ;-)  IOW, taking care of directory
> > modifications is not enough - you need to deal with
> > 	* opening file for write
> > 	* truncation (both from *truncate() and from open() with O_TRUNC)
> > 	* metadata changes (timestamps, ownership, permissions)
> 
> well, the open case, IMHO is handled by the
> lookup_create() modifications, truncate is something

more descriptive would have been:
- I guess this is handled in open_namei() by

     error = -EROFS;
     if ((flag & 2) && (IS_RDONLY(inode) || MNT_IS_RDONLY(nd->mnt)))
            goto exit;

> best,
> Herbert
-
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