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From: jeff@quark.WV.TEK.COM (Jeff Beadles)
Newsgroups: comp.unix.wizards
Subject: Re: NFS and UFS Mounting on a non-empty directory
Keywords: Frustration, Yellow Pages
Message-ID: <4000@orca.WV.TEK.COM>
Date: 23 Jul 89 21:00:02 GMT
References: <2339@orion.cf.uci.edu> <12921@bloom-beacon.MIT.EDU> <1989Jul23.194057.4247@ctr.columbia.edu>
Sender: nobody@orca.WV.TEK.COM
Reply-To: jeff@quark.WV.TEK.COM (Jeff Beadles)
Distribution: na
Organization: Tektronix, Inc., Wilsonville, OR
Lines: 50

>In article <12921@bloom-beacon.MIT.EDU> jik@athena.mit.edu (Jonathan I. Kamens) writes:
>>Yes, the concept of mounting over a non-empty directory is
>>well-defined
>>>     Its
>>>     old contents are inaccessible while the file system is
>>>     mounted.


In article <1989Jul23.194057.4247@ctr.columbia.edu> seth@ctr.columbia.edu (Seth Robertson) writes:
>The concept may be well defined, but the implementation bytes the big one.
>In SunOS 4.0.3

>seth elara> cd /mnt
>seth elara> ls
>testfile
>seth elara> cat testfile
>This is a test.
>seth elara> mount leda:/image /mnt

[ Stuff deleted ]


I think that your Sun has a fairly serious problem if it allowed you to do
this.  If the above is what you did, you SHOULD get a 'mount point busy' as you
are in /mnt when you mount on top if it.
(The same would apply for unmount/umount)


This is what happens under Utek (4.2 based BSD, with NFS)

Script started on Sun Jul 23 13:54:16 1989
rq:jeff> cd /tmp
rq:tmp> mkdir foo
rq:tmp> cd foo
rq:foo> /etc/mount tango:/ /tmp/foo
mount: tango:/ on /tmp/foo: Device busy
mount: giving up on:
   /tmp/foo
rq:foo> /etc/mount | egrep tango
rq:foo> cd /
rq:tmp> rmdir /tmp/foo
rq:tmp> ^D
script done on Sun Jul 23 13:55:13 1989


	-Jeff

-- 
Jeff Beadles		Utek Sustaining Engineering, Tektronix Inc.
jeff@quark.WV.TEK.COM