Comment 22 for bug 644489

I can understand that. Attached is a debdiff of the updated package.
I must stress that may not be the final form of the solution. I'm
chatting with Douglas Gilbert (sg io maintainer) now about this.
So far it appears that using an SD device as the target for sg io
can have unintended side effects, like the ones we've been observing.
If the corresponding SG device was used to begin with, this problem
would have never occurred.

See for yourself, mpath_prio_netapp /dev/sg0

In the meanwhile, this patch adjusts the open flag s.t. the "side effect"
no longer occurs. What's annoying is the upstream multipath (0.4.9) is
still using SD devices for this work but they did change all of their
open flags to O_RDONLY. Which leads me to believe they worked around
this side effect too, perhaps unaware of the fact that they were causing
these events to begin with by using sd devices by default.

You can simply build the mpath_prio_netapp straight from
path_priority/pp_netapp/ assuming build deps are met.