Okay, when doing some other stuff I looked over this one, and it's
a bit confusing to read:

 - using a goto completed where a simple break would be sufficient
 - using for (;;) for a perfectly fine while loop
 - ...

but what's more interesting is that the spinlock handling in here,
when we switch from sdev_lock/queue_lock to host_lock we
do a spin_unlock_irq followed by a spin_lock_irqsave - but we
we just enabled interrupts so the save isn't nessecary at all, even
more we can just do spin_unlock/spin_lock when keeping them
disabled.  Also we drop host_lock in the middle of this function,
just to reacquire it a tad later in scsi_dispatch_cmd, but fixing
that need a bit more thinking as there's another caller for
scsi_dispatch_cmd.