[Stgt-devel] segfault in the ssc code ...

[Richard Sharpe]

On Fri, Jul 25, 2008 at 7:19 PM, Mark Harvey <markh794 at gmail.com> wrote:
> Richard Sharpe wrote:
>>
>> On Fri, Jul 25, 2008 at 2:31 PM, Richard Sharpe
>> <realrichardsharpe at gmail.com> wrote:
>>>
>>> Hi,
>>>
>>> There is a segfault in the ssc code when using it with the smc code
>>> because it seems that bs_ssc_open is not called when you move a tape
>>> into the transfer unit.
>>>
>>> I am currently looking at what the best approach is here, but it seems
>>> the smc.c code calls target.c:dtd_load_unload which calls
>>> backed_file_open, but it seems that nothing calls bs_thread_open, so
>>> later when a bs_thread_cmd_submit is called, the pending_list is not
>>> initialized and we segfault.
>>>
>>> I am currently wading through the code to see if I can figure out
>>> where this should be set up. It would seem like it should be done when
>>> we move a unit into the transfer station in the smc.c code but I am
>>> not sure.
>>
>> I was wondering if this change would do the trick:
>>
>> In usr/smc.c, change set_slot_full to take a target structure as well
>> as the other args, and from that call tgt_set_device_path_update,
>> which will also call the correct things ...
>>
>> and in set_slot_empty, also call tdt_set_device_path_update ...
>
> When I put this bit into the code, I was thinking something like "exec
> tgtadm .... <with options to update backing store>"
>
> Where the backing store consists of a path prefix along with the 'barcode'
> as the filename.
>
> I'm sure there is a neater method however.
>
> The same thing is required for the MMC device as well (for a Virtual CD/DVD
> Library).

Hmmm, while I have stuff mostly working, further examination showed
that I should have passed --params bstype=ssc or something like that
when I created the virtual tape drive, in which case I would get the
correct backing store module, I think ...