Re: Mounting NFS several times
In article <20020716165153.GA14205@alcor.net>,
Matt Zimmerman <email@example.com> wrote:
>You can mount as many things as you want on the same mount point, period.
>There is nothing wrong or inconsistent about that.
>However, you can only mount a particular device once, regardless of the
>mount point, because otherwise things would break.
You haven't used a 2.4 kernel yet have you. With 2.4 kernels,
you can mount the same device, say /dev/hda1, in
different places at the same time.
# mount /dev/hda1 /mnt
/dev/hda1 on / type ext3 (rw)
/dev/hda6 on /usr type ext3 (rw)
/dev/hda7 on /var type ext3 (rw,noatime)
/dev/hda8 on /home type ext3 (rw,noatime)
/dev/hda1 on /mnt type ext3 (rw)
In earlier 2.4 kernels you could also mount the same device on
the same mountpoint multiple times, but it confused the hell
out of the users. So somewhere in 2.4 (2.4.18 ?) this was
changed to specifically prevent this case.
See fs/namespace::do_add_mount() of a recent 2.4 kernel
However it appears that for NFS this restriction doesn't work.
I don't think it is useful to guess why this is so; I read the
code and its probably a bug in the do_add_mount() check.
Someone should bring this up on the linux-kernel mailinglist
so that Al can fix it.
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