Skip site navigation (1)Skip section navigation (2)
Date:      Mon, 15 Jan 1996 07:26:34 +1100
From:      Bruce Evans <bde@zeta.org.au>
To:        bde@zeta.org.au, gibbs@freefall.freebsd.org
Cc:        freebsd-scsi@freefall.freebsd.org
Subject:   Re: Calling st_unmount for nrst* devices
Message-ID:  <199601142026.HAA17864@godzilla.zeta.org.au>

next in thread | raw e-mail | index | archive | help
>>Because then there would be complications involving how long-lived
>>the settings are.  You would need two control devices, one to set
>>the defaults that are restored at the end of a mount session and
>>a new one to control mount sessions.  You would also need a new
>>command to end mount sessions.

>I just don't see this.  A mount session ends when you close the device.
>When you open a device, a new mount session is started and the settings
>from the control device are enforced.  The only difference between the
>nrst* devices and rst* devices is that a close will rewind the tape.

This would defeat the point of the current control device which is
to give almost fixed system defaults for the next mount session.

>It just doesn't make sence that a closed device cannot be removed
>externally (ie from the eject button on my tape drive).  There is

Agreed.  Perhaps there should be a special device that is open
through the mount session.  It can't be the standard device because
you want to see closes of the standard device as last-closes, e.g.,
for auto-rewind on close.

>also the problem that the busy light stays on for as long as the media
>is locked.  Consider this:

>mt /dev/rst0 rewind
>dump 0uBf 2033646 /dev/nrst0 /dev/sd0s2e
>dump 0uBf 2033646 /dev/nrst0 /dev/sd0s2f
>mt /dev/rst0 rewind

>Now, can I go over to my machine after this runs and eject the media?
>Nope.  Even though mt uses the rewinding device (which should end the mount
>session according to the man page), the mount session isn't closed because
>we only do an ioctl and that ioctl only performs an st_rewind.

(At first I thought you meant nrst0 because the explicit rewinds are
unecessary for rst0.)

Eject works here after similar operations on a Wangdat 3100:

mt -f /dev/nrst0 blocksize 0
od /dev/nrst0	# failed
mt -f /dev/rst0 rewind

>>enough for this to be practical :-).  I don't want an auto offline on
>>rewind.  Allowing eject at any time that the hardware does and mount
>>sessions extending across ejects might be useful, however.

>Who said anything about an auto offline.  Ending a mount session doesn't
>imply an eject.  The only time the eject will happen is if you opened the
>ejecting device or, with my changes, if the nrst device is closed and you
>go hit the eject button on the drive.

I was confusing mount sessions with physical mounts/offlines and that's
more or less what they are here.  Eject permission is too closely tied
to being offline.  Perhaps there is no difference for some hardware.

Bruce



Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199601142026.HAA17864>