Exemplo n.º 1
0
// Examines /proc/mounts to find the source device of the PD resource and the
// number of references to that device. Returns both the full device path under
// the /dev tree and the number of references.
func getMountRefCount(mounter mount.Interface, mountPath string) (string, int, error) {
	// TODO(jonesdl) This can be split up into two procedures, finding the device path
	// and finding the number of references. The parsing could also be separated and another
	// utility could determine if a path is an active mount point.

	mps, err := mounter.List()
	if err != nil {
		return "", -1, err
	}

	// Find the device name.
	deviceName := ""
	for i := range mps {
		if mps[i].Path == mountPath {
			deviceName = mps[i].Device
			break
		}
	}

	// Find the number of references to the device.
	refCount := 0
	for i := range mps {
		if mps[i].Device == deviceName {
			refCount++
		}
	}
	return deviceName, refCount, nil
}
// getDevicePrefixRefCount: given a prefix of device path, find its reference count from /proc/mounts
// returns the reference count to the device and error code
// for services like iscsi construct multiple device paths with the same prefix pattern.
// this function aggregates all references to a service based on the prefix pattern
// More specifically, this prefix semantics is to aggregate disk paths that belong to the same iSCSI target/iqn pair.
// an iSCSI target could expose multiple LUNs through the same IQN, and Linux iSCSI initiator creates disk paths that start the same prefix but end with different LUN number
// When we decide whether it is time to logout a target, we have to see if none of the LUNs are used any more.
// That's where the prefix based ref count kicks in. If we only count the disks using exact match, we could log other disks out.
func getDevicePrefixRefCount(mounter mount.Interface, deviceNamePrefix string) (int, error) {
	mps, err := mounter.List()
	if err != nil {
		return -1, err
	}

	// Find the number of references to the device.
	refCount := 0
	for i := range mps {
		if strings.HasPrefix(mps[i].Device, deviceNamePrefix) {
			refCount++
		}
	}
	return refCount, nil
}