[libvirt] [RFC 0/5]: Fix up iSCSI handling (again)

[Chris Lalancette]

All,
     I've been sitting on this for way too long, so I'm sending these patches
out for some initial review while I continue to test them.  The following 5
patches rework the iSCSI LUN scanning again.  The aim here is to:

1)  Do minor cleanup of the existing code
2)  Fix a bug where we aren't properly finding the LUNs on pre 2.6.24 kernels
3)  Fix a bug seen in oVirt where we race between libvirtd scanning the sysfs
path and udev actually making the sysfs path in the first place
4)  Further lessen our dependence on direct calls to iscsiadm, in case they
change the output in the future.

I've started testing this patchset against a variety of Fedora's, old and new.
Anything older than FC-6 is a lost cause; either it doesn't have iSCSI stuff
(FC-1 through FC-4), or the iscsi stuff it has is so radically different that
it's basically a different commandset (RHEL-4 and FC-5).  In some light testing,
though, this patchset seems to work on FC-6, F-7, F-8, and F-9 (RHEL-5 still to
be tested).

As Dan mentioned earlier, I have collected output from the relevant iscsiadm
commands so that we can build our own fake iscsiadm in tests; I'll be working on
that test as well as continuing to test these patches against live iSCSI targets.

Note that this patchset is not to be applied yet; I've only lightly tested it so
far.  I'd just like to see what people think about all of this.

Chris Lalancette