acahalan@cs.uml.edu (acahalan@cs.uml.edu) writes:
> From: acahalan@cs.uml.edu
> To: linux-kernel@vger.rutgers.edu
> Cc: viro@math.psu.edu
> Message-ID: <2swOlax70cevgQcM.hT5nAtuM3skeaxU47CvCnNO7oWxqJ5f>
> Date: the sixth of June, in the year of our lord two thousand
> X-Mailer: telnet
>
> Alexander Viro writes:
> > On Wed, 7 Jun 2000, James Sutherland wrote:
>
> >>> A) suppose we have a bunch of filesystems union-mounted on
> >>> /foo/bar. We do chdir("/foo/bar"), what should become busy? Variants:
> >>> mountpoint, first element, last element, all of them.
> >>
> >> The key question, presumably, is which FSs can we unmount from the union
> >> without /foo/bar breaking? If all the FSs can be unmounted safely, none
> >> should be busy.
>
> This is right. Being "busy" is a traditional UNIX flaw.
Whether or not it is a "flaw" is arguable. The point is, this is the way it
works. Any sysadmin knows the way to umount mounted directories is to start
at the lowest mount point and work your way up - anything else is inviting
problems.
df:
host:/ blah blah /host/root
host:/usr ... ... /host/root/usr
The proper way to umount is "umount /host/root/usr;umount /host/root". I
dislike trying to put hacks in VFS because people don't understand how it's
supposed to work and automatically assumes that it's broken. What is broken
is people's understanding, not the way it works.
-- Ed Carp, N7EKG erc@pobox.com 940/367-2744 cell phone http://www.pobox.com/~erc- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
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