This is an update that allows the iscsi volume to check if a iscsi device belongs to a mpio device

If it does belong to the device then we make sure we mount the mpio device instead of
the raw device.

Heuristics
Login into /dev/disk/by-path/iqn-example.com.2999 -> /dev/sde
Check if sde existsin in /sys/block/[dm-X]/slaves/xx
If it does mount /dev/[dm-x] which will look like /dev/mapper/mpiodevicename in mount

examples/iscsi has more details

pkg/volume/fc/fc_util.go

@@ -51,6 +51,8 @@ func (handler *osIOHandler) WriteFile(filename string, data []byte, perm os.File
 }
 
 // given a disk path like /dev/sdx, find the devicemapper parent
+// TODO #23192 Convert this code to use the generic code in ../util
+// which is used by the iSCSI implementation
 func findMultipathDeviceMapper(disk string, io ioHandler) string {
 	sys_path := "/sys/block/"
 	if dirs, err := io.ReadDir(sys_path); err == nil {