[stgt] [PATCH] Add support for PREVENT/ALLOWMEDIUMREMOVAL and STARTSTOPUNIT

[FUJITA Tomonori]

On Sat, 28 Jan 2012 01:16:41 +0900
FUJITA Tomonori <fujita.tomonori at lab.ntt.co.jp> wrote:

> On Fri, 27 Jan 2012 16:12:20 +1100
> ronnie sahlberg <ronniesahlberg at gmail.com> wrote:
> 
> > From 17fdaf426120d6167b7f14068d7c6f4ca0322217 Mon Sep 17 00:00:00 2001
> > From: Ronnie Sahlberg <ronniesahlberg at gmail.com>
> > Date: Fri, 27 Jan 2012 16:07:00 +1100
> > Subject: [PATCH] Add PREVENT/ALLOW MEDIUM REMOVAL and START STOP UNIT
> > 
> > Implement logic for PAMR and SSU.
> > 
> > Add a new attribute .prevent to track the allow prevent removal status of a LUN.
> > Implement PAMR and update the LUN attribute accordingly.
> > 
> > Units where PAMR is set to prevent removal of the device can not be
> > made offline using tgtadm. Attempts to make the unit offline
> > will fail with a new TGTADM error to indicate there is a PAMR lock on the device.
> > 
> > SSU attempts to "eject" the media will fail with a check condition
> > if the media is locked by PAMR.
> > 
> > If SSU successfully "ejects" the media, we automatically set the LUN to "Offline".
> > 
> > Update tgt_target_show_all() to show the PreventRemoval status for the LUN in the output.
> > 
> > Signed-off-by: Ronnie Sahlberg <ronniesahlberg at gmail.com>
> > ---
> >  doc/tgtadm.8.xml   |   47 +++++++++++++++++++++++++++++++++++++++++++++++
> >  usr/mmc.c          |   10 ++--------
> >  usr/sbc.c          |    2 +-
> >  usr/spc.c          |   43 ++++++++++++++++++++++++++++++++++++-------
> >  usr/target.c       |   15 +++++++++++++--
> >  usr/tgtadm.c       |    4 +++-
> >  usr/tgtadm_error.h |    2 ++
> >  usr/tgtd.h         |    5 +++++
> >  8 files changed, 109 insertions(+), 19 deletions(-)
> 
> Thanks a lot! Another "TODO: implement properly" comment removal!
> 
> SPC3 says:
> 
> The prevention of medium removal shall begin when any application
> client issues a PREVENT ALLOW MEDIUM REMOVAL command with a PREVENT
> field of 01b or 11b (i.e., medium removal prevented). The prevention
> of medium removal for the logical unit shall terminate after:
> 
> a) One of the following occurs for each I_T nexus that previously had
> medium removal prevented:
>    A) Receipt of a PREVENT ALLOW MEDIUM REMOVAL command with a PREVENT
>    field of 00b or 10b;
>    B) An I_T nexus loss; or
> 
> With the current code, even an I_T nexus that previously had NOT
> medium removal prevented can terminate the prevention of medium
> removal? Is that against the spec, No?

And of course, we need to terminate the prevention of medium removal
when the I_T nexus that previously had medium removal prevented
loses. So I guess that we need some data structures per nexus for this
feature.
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