// checks if the required cgroups subsystems are mounted.
// As of now, only 'cpu' and 'memory' are required.
func validateSystemRequirements(mountUtil mount.Interface) error {
const (
cgroupMountType = "cgroup"
localErr = "system validation failed"
)
mountPoints, err := mountUtil.List()
if err != nil {
return fmt.Errorf("%s - %v", localErr, err)
}
expectedCgroups := sets.NewString("cpu", "cpuacct", "cpuset", "memory")
for _, mountPoint := range mountPoints {
if mountPoint.Type == cgroupMountType {
for _, opt := range mountPoint.Opts {
if expectedCgroups.Has(opt) {
expectedCgroups.Delete(opt)
}
}
}
}
if expectedCgroups.Len() > 0 {
return fmt.Errorf("%s - Following Cgroup subsystem not mounted: %v", localErr, expectedCgroups.List())
}
return 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
}
