LSI 9200-8e/gmultipath/ZFS cable pull kernel crash

[Matthew Jacob]

> dd if=/dev/zero bs=1m | mbuffer -m 64m -o /lsi/bigfile
>
> with mbuffer reporting the following
>
> in @  697 MiB/s, out @  697 MiB/s, 11.8 GiB total, buffer 100% full
>
> when I pull the cable. Playing with it today, I'm wondering if the
> 1st cable actually has any active providers on it (luck of the
> draw that I pulled it first), and the 2nd has all the active
> providers on it.  I have not explicity tried to balance the i/o
> on the two cables with gmultipath rotate.
>
> Having a bit of trouble getting a good objdump of g_multipath.o
> so I may do a new src update.

I had to do a wad of changes at Panasas to cover this kind of case. I have 
had some troubles getting these changes into -head (lack of time, 
differences from the RELENG_7 code I was working with, etc), but I think 
that there are still issues at play here.