util: Introduce virStorageFileGetNPIVKey

util: Introduce virStorageFileGetNPIVKey

The vHBA/NPIV LUNs created via the udev processing of the
VPORT_CREATE command end up using the same serial value
as seen/generated by the /lib/udev/scsi_id as returned
during virStorageFileGetSCSIKey. Therefore, in order to
generate a unique enough key to be used when adding the
LUN as a volume during virStoragePoolObjAddVol a more
unique key needs to be generated for an NPIV volume.

The problem is illustrated by the following example, where
scsi_host5 is a vHBA used with the following LUNs:

$ lsscsi -tg
...
[5:0:4:0]    disk    fc:0x5006016844602198,0x101f00  /dev/sdh   /dev/sg23
[5:0:5:0]    disk    fc:0x5006016044602198,0x102000  /dev/sdi   /dev/sg24
...

Calling virStorageFileGetSCSIKey would return:

/lib/udev/scsi_id --device /dev/sdh --whitelisted --replace-whitespace /dev/sdh
350060160c460219850060160c4602198
/lib/udev/scsi_id --device /dev/sdh --whitelisted --replace-whitespace /dev/sdi
350060160c460219850060160c4602198

Note that althrough /dev/sdh and /dev/sdi are separate LUNs, they
end up with the same serial number used for the vol->key value.
When virStoragePoolFCRefreshThread calls virStoragePoolObjAddVol
the second LUN fails to be added with the following message
getting logged:

    virHashAddOrUpdateEntry:341 : internal error: Duplicate key

To resolve this, virStorageFileGetNPIVKey will use a similar call
sequence as virStorageFileGetSCSIKey, except that it will add the
"--export" option to the call. This results in more detailed output
which needs to be parsed in order to formulate a unique enough key
to be used. In order to be unique enough, the returned value will
concatenate the target port as returned in the "ID_TARGET_PORT"
field from the command to the "ID_SERIAL" value.

Signed-off-by: John Ferlan <jferlan@redhat.com>
ACKed-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>