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

[FUJITA Tomonori]

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?
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