[9fans] Unmount a USB stick?

[9fans] Unmount a USB stick?

[devrin talen]

I've got a USB stick that I've been using to shuttle a few docs
around. I googled a bit and I've been using:

% usb/disk -l
% usbfat:

to mount the stick. That works all well and good, but how do I go
about ejecting it gracefully? I've tried:

% unmount /n/usb
% unmount /n/disk

But have no idea if that's the right way to go about it. Additionally
if I eject it in this manner the next time I try to mount it using the
first two commands I get a bunch of usb errors.

Also, why is the disk only available from the rc window that I used to
mount it? In any other rc window I can't access the /n/usb mountpoint.
I realize I'm probably missing something fundamental about plan 9
(newbie here).

- Devrin

Re: [9fans] Unmount a USB stick?

[erik quanstrom]

>
> % unmount /n/usb
> % unmount /n/disk
>
> But have no idea if that's the right way to go about it. Additionally
> if I eject it in this manner the next time I try to mount it using the
> first two commands I get a bunch of usb errors.

you have to restart usbd.  usbd doesn't handle device ejection as far
as i can tell.

> Also, why is the disk only available from the rc window that I used to
> mount it? In any other rc window I can't access the /n/usb mountpoint.
> I realize I'm probably missing something fundamental about plan 9
> (newbie here).

this is because rio puts each window in a sepeate namespace.  there are
two ways around this.  first, start this before you start rio.  (alternatively
use the plumber to give all new windows access.  plumb a string like
	Local 'cmd for everyone to see'
) alternatively, you can use /srv to post the fd.

- erik

Re: [9fans] Unmount a USB stick?

[a]

// ...why is the disk only available from the rc window
// that I used to mount it?

Each rio window gets its own namespace from rio. Changes in
one will not affect others; this is central to the Plan 9's per-
process namespaces.

srvfs(4) is often useful for getting portions of one namespace
into another.
Anthony

Re: [9fans] Unmount a USB stick?

[geoff]

[-- Attachment #1: Type: text/plain, Size: 570 bytes --]

I believe dossrv (which implements the fat filesystem) is synchronous,
so you shouldn't have to do anything special before removing the
stick.  What are the errors you get the next time you try to mount the
stick?

> you have to restart usbd.  usbd doesn't handle device ejection as
> far as i can tell.

I'm pretty sure that it's more nuanced than that.  I've been able to
eject and re-insert usb devices on uhci interfaces.  I think the
problems with usbd not noticing device additions and removals is
limited to ohci interfaces, and I'm not sure why yet.

[-- Attachment #2: Type: message/rfc822, Size: 2477 bytes --]

From: erik quanstrom <quanstro@coraid.com>
To: 9fans@9fans.net
Subject: Re: [9fans] Unmount a USB stick?
Date: Thu, 3 Apr 2008 18:17:42 -0400
Message-ID: <01044970cb30fd41a02e19818ead294e@coraid.com>

>
> % unmount /n/usb
> % unmount /n/disk
>
> But have no idea if that's the right way to go about it. Additionally
> if I eject it in this manner the next time I try to mount it using the
> first two commands I get a bunch of usb errors.

you have to restart usbd.  usbd doesn't handle device ejection as far
as i can tell.

> Also, why is the disk only available from the rc window that I used to
> mount it? In any other rc window I can't access the /n/usb mountpoint.
> I realize I'm probably missing something fundamental about plan 9
> (newbie here).

this is because rio puts each window in a sepeate namespace.  there are
two ways around this.  first, start this before you start rio.  (alternatively
use the plumber to give all new windows access.  plumb a string like
	Local 'cmd for everyone to see'
) alternatively, you can use /srv to post the fd.

- erik

Re: [9fans] Unmount a USB stick?

[erik quanstrom]

> I'm pretty sure that it's more nuanced than that.  I've been able to
> eject and re-insert usb devices on uhci interfaces.  I think the
> problems with usbd not noticing device additions and removals is
> limited to ohci interfaces, and I'm not sure why yet.

this very well could be.  i have not been able to do much testing
with intel-style usb.

- erik

Re: [9fans] Unmount a USB stick?

[devrin talen]

On Thu, Apr 3, 2008 at 6:28 PM,  <geoff@plan9.bell-labs.com> wrote:
> I believe dossrv (which implements the fat filesystem) is synchronous,
>  so you shouldn't have to do anything special before removing the
>  stick.  What are the errors you get the next time you try to mount the
>  stick?

If I have mounted the stick, then try to exit the rc window with which
I mounted it:

% exit

the window hangs indefinitely. If I delete the window, remove the
stick, reinsert it, then in a new rc window type:

% echo kill > /proc/86/notes # 86 is the pid of usbd
% usb/usbd
% usb/disk -l
usb/disk: describedevice: error reading usb device descriptor, got 0 of 18:

usb/disk: maxlun 0

and a few black boxes in the upper left of my screen with messages such as:

CleanTD 1/0: Error 00000001 ...

Usually at this point I just end up restarting the box, and I'll be
able to use the stick once again.

- Devrin

Re: [9fans] Unmount a USB stick?

[erik quanstrom]

>
> % echo kill > /proc/86/notes # 86 is the pid of usbd
> % usb/usbd
> % usb/disk -l
> usb/disk: describedevice: error reading usb device descriptor, got 0 of 18:
>
> usb/disk: maxlun 0
>
> and a few black boxes in the upper left of my screen with messages such as:
>
> CleanTD 1/0: Error 00000001 ...
>
> Usually at this point I just end up restarting the box, and I'll be
> able to use the stick once again.

trick 'o the day: keep kernel messages from messing with rio:
	window -hide rc -c 'label kmesg ; tail -f /dev/kprint'
as long as you have someone reading kernel messages, they won't
be written directly to the screen.

what happens when you do the following:

	slay usbd|rc
	slay disk|rc
	usb/usbd; usb/disk -l


- erik

Re: [9fans] Unmount a USB stick?

[devrin talen]

On Thu, Apr 3, 2008 at 8:41 PM, erik quanstrom <quanstro@quanstro.net> wrote:
>  trick 'o the day: keep kernel messages from messing with rio:
>         window -hide rc -c 'label kmesg ; tail -f /dev/kprint'
>  as long as you have someone reading kernel messages, they won't
>  be written directly to the screen.

Thanks!

>  what happens when you do the following:
>
>         slay usbd|rc
>         slay disk|rc
>         usb/usbd; usb/disk -l

% usb/usbd; usb/disk -l
usb/disk: maxlun 0

But then I try

% usbfat:
mount: mount /n/usb: '/n/disk/0' i/o on hungup channel

Is that an effect of me killing the window earlier?

Re: [9fans] Unmount a USB stick?

[Richard Miller]

> Additionally
> if I eject it in this manner the next time I try to mount it using the
> first two commands I get a bunch of usb errors.

There is a problem with usbd (and uhci?) on reinsertion of some
but not all devices.  Also the usbfat: script makes an entry in '#s'
which needs to be cleaned up.  You should find this works to undo
everything so the usb disk can be removed and reinserted:

  unmount /n/usb
  unmount /n/disk
  rm /srv/usbfat.$user
  kill usbd | rc
  usb/usbd

> Also, why is the disk only available from the rc window that I used to
> mount it?

To see the disk in another window, just type usbfat: there -- the
script uses the /srv/usbfat.$user entry to check for an existing service.

Re: [9fans] Unmount a USB stick?

[Richard Miller]

I should have tried it myself before saying confidently:

> To see the disk in another window, just type usbfat: there

In fact usbfat: doesn't quite do the right thing.

You can either fix /rc/bin/usbfat: by moving the lines
	if (! test -e $disk)
		usb/disk $opts || exit 'no disk'
to follow the line
  if (! test -f /srv/usbfat.$user) {

or else just use
  mount -c /srv/usbfat.$user /n/usb
to mount an already-mounted usb disk in another window.