Rename IsMountPoint to IsLikelyNotMountPoint

IsLikelyNotMountPoint determines if a directory is not a mountpoint.
It is fast but not necessarily ALWAYS correct. If the path is in fact
a bind mount from one part of a mount to another it will not be detected.
mkdir /tmp/a /tmp/b; mount --bin /tmp/a /tmp/b; IsLikelyNotMountPoint("/tmp/b")
will return true. When in fact /tmp/b is a mount point. So this patch
renames the function and switches it from a positive to a negative (I
could think of a good positive name). This should make future users of
this function aware that it isn't quite perfect, but probably good
enough.

pkg/volume/aws_ebs/aws_util.go

@@ -61,13 +61,13 @@ func (util *AWSDiskUtil) AttachAndMountDisk(b *awsElasticBlockStoreBuilder, glob
 	}
 
 	// Only mount the PD globally once.
-	mountpoint, err := b.mounter.IsMountPoint(globalPDPath)
+	notMnt, err := b.mounter.IsLikelyNotMountPoint(globalPDPath)
 	if err != nil {
 		if os.IsNotExist(err) {
 			if err := os.MkdirAll(globalPDPath, 0750); err != nil {
 				return err
 			}
-			mountpoint = false
+			notMnt = true
 		} else {
 			return err
 		}
@@ -76,7 +76,7 @@ func (util *AWSDiskUtil) AttachAndMountDisk(b *awsElasticBlockStoreBuilder, glob
 	if b.readOnly {
 		options = append(options, "ro")
 	}
-	if !mountpoint {
+	if notMnt {
 		err = b.diskMounter.Mount(devicePath, globalPDPath, b.fsType, options)
 		if err != nil {
 			os.Remove(globalPDPath)