[SPARK-4792] Add error message when making local dir unsuccessfully

Author: meiyoula <[email protected]>

Closes apache#3635 from XuTingjun/master and squashes the following commits:

dd1c66d [meiyoula] when old is deleted, it will throw an exception where call it
2a55bc2 [meiyoula] Update DiskBlockManager.scala
1483a4a [meiyoula] Delete multiple retries to make dir
67f7902 [meiyoula] Try some times to make dir maybe more reasonable
1c51a0c [meiyoula] Update DiskBlockManager.scala

Author: XuTingjun

core/src/main/scala/org/apache/spark/storage/DiskBlockManager.scala

@@ -17,7 +17,7 @@
 
 package org.apache.spark.storage
 
-import java.io.File
+import java.io.{IOException, File}
 import java.text.SimpleDateFormat
 import java.util.{Date, Random, UUID}
 
@@ -71,7 +71,9 @@ private[spark] class DiskBlockManager(blockManager: BlockManager, conf: SparkCon
           old
         } else {
           val newDir = new File(localDirs(dirId), "%02x".format(subDirId))
-          newDir.mkdir()
+          if (!newDir.exists() && !newDir.mkdir()) {
+            throw new IOException(s"Failed to create local dir in $newDir.")
+          }
           subDirs(dirId)(subDirId) = newDir
           newDir
         }