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Subject: Re: [RFC] shared subtrees
From: Ram <linuxram@us.ibm.com>
To: Mike Waychison <Michael.Waychison@Sun.COM>
Cc: "J. Bruce Fields" <bfields@fieldses.org>,
       Al Viro <viro@parcelfarce.linux.theplanet.co.uk>,
       linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
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On Tue, 2005-01-25 at 13:47, Mike Waychison wrote:
 ...snip...
> > 
> > Question 2:
> > 
> > When a mount gets propogated to a slave, but the slave
> > has mounted something else at the same place, and hence 
> > that mount point is masked, what will happen?
> > 
> >         Concrete example:
> > 
> >         mount <device1> /tmp/mnt1
> >         mkdir -p /tmp/mnt1/a/b
> >         mount --rbind /tmp/mnt1 /tmp/mnt2
> >         mount --make-slave /tmp/mnt2
> 
> EINVAL.  You should only be able to demote a mountpoint to a slave if it
> was part of a p-node (shared).

oops. I had the following in mind.

	mount <device1> /tmp/mnt1
      **  mount --make-shared /tmp/mnt1  **
        mkdir -p /tmp/mnt1/a/b
        mount --rbind /tmp/mnt1 /tmp/mnt2
        mount --make-slave /tmp/mnt2

In this case it cannot be EINVAL, because /tmp/mnt1 and /tmp/mnt2 will
both be part of a pnode and hence /tmp/mnt2 can be demoted to be a
slave. 
> 
> >         mount <device2> /tmp/mnt2/a
> >         rm -f /tmp/mnt2/a/*
> > 
> >         what happens when a mount is attempted on /tmp/mnt1/a/b?
> >         will that be reflected in /tmp/mnt2/a ?
> > 
> >         I believe the answer is 'no', because that part of the subtree 
> >         in /tmp/mnt2 no more mirrors its parent subtree.
> > 
> > RP 
> > 
> > -
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> 
> 
> - --
> Mike Waychison
> Sun Microsystems, Inc.
> 1 (650) 352-5299 voice
> 1 (416) 202-8336 voice
> 
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> NOTICE:  The opinions expressed in this email are held by me,
> and may not represent the views of Sun Microsystems, Inc.
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