Static Load balancing prioritizer

Static Load balancing prioritizer

'Weighted path' is a new path prioritizer for device mapper
multipath, where specific paths and the corresponding priority
values can be provided as arguments.
This prioritizer assigns the priority value provided in the
configuration file based on the comparison made between the
specified paths and the path instance for which this is called.
Paths can be specified as a regular expression of devname
of the path or as hbtl information of the path.

Syntax:
weightedpath  <hbtl|devname> <regex1> <prio1> <regex2> <prio2> ...

Examples:
prio  "weightedpath"
prio_args "hbtl 1:.:.:. 2 4:.:.:. 4"

prio  "weightedpath"
prio_args "devname sda$ 10 sde$ 20"

This prioritizer allows user to set static load balancing
for devices. Useful when user has prior knowledge of path
performance difference or unavailability of certain paths.

Signed-off-by: Vijayakumar Balasubramanian <vijaykumar@hp.com>
Signed-off-by: Hannes Reinecke <hare@suse.de>