Remove peekInode(boolean) method.

Replace it with two methods:
1. peekInode() that always returns the last existing inode in the
InodePath, or null if there is none.
2. getParent() that returns the parent of the target inode, or null if
the parent does not exist.

core/server/master/src/main/java/alluxio/master/file/DefaultFileSystemMaster.java

@@ -1107,8 +1107,12 @@ public long createFile(AlluxioURI path, CreateFileOptions options)
     try (JournalContext journalContext = createJournalContext();
         LockedInodePath inodePath = mInodeTree.lockInodePath(path, InodeTree.LockMode.WRITE);
         MasterAuditContext auditContext =
-             createAuditContext("createFile", path, null,
-                 inodePath.peekInode(options.isRecursive()))) {
+             createAuditContext("createFile", path, null, null)) {
+      if (options.isRecursive()) {
+        auditContext.setSrcInode(inodePath.peekInode());
+      } else {
+        auditContext.setSrcInode(inodePath.getParentInode());
+      }
       try {
         mPermissionChecker.checkParentPermission(Mode.Bits.WRITE, inodePath);
       } catch (AccessControlException e) {
@@ -1823,8 +1827,12 @@ public long createDirectory(AlluxioURI path, CreateDirectoryOptions options)
     try (JournalContext journalContext = createJournalContext();
         LockedInodePath inodePath = mInodeTree.lockInodePath(path, InodeTree.LockMode.WRITE);
         MasterAuditContext auditContext =
-             createAuditContext("mkdir", path, null,
-                 inodePath.peekInode(options.isRecursive()))) {
+             createAuditContext("mkdir", path, null, null)) {
+      if (options.isRecursive()) {
+        auditContext.setSrcInode(inodePath.peekInode());
+      } else {
+        auditContext.setSrcInode(inodePath.getParentInode());
+      }
       try {
         mPermissionChecker.checkParentPermission(Mode.Bits.WRITE, inodePath);
       } catch (AccessControlException e) {
@@ -1914,7 +1922,7 @@ public void rename(AlluxioURI srcPath, AlluxioURI dstPath, RenameOptions options
         MasterAuditContext auditContext = createAuditContext("rename", srcPath, dstPath, null)) {
       LockedInodePath srcInodePath = inodePathPair.getFirst();
       LockedInodePath dstInodePath = inodePathPair.getSecond();
-      auditContext.setSrcInode(srcInodePath.peekInode(false));
+      auditContext.setSrcInode(srcInodePath.getParentInode());
       try {
         mPermissionChecker.checkParentPermission(Mode.Bits.WRITE, srcInodePath);
         mPermissionChecker.checkParentPermission(Mode.Bits.WRITE, dstInodePath);
@@ -2382,8 +2390,12 @@ public long loadMetadata(AlluxioURI path, LoadMetadataOptions options)
       InvalidFileSizeException, FileAlreadyCompletedException, IOException, AccessControlException {
     try (JournalContext journalContext = createJournalContext();
         LockedInodePath inodePath = mInodeTree.lockInodePath(path, InodeTree.LockMode.WRITE);
-        MasterAuditContext auditContext = createAuditContext("loadMetadata", path, null,
-            inodePath.peekInode(options.isCreateAncestors()))) {
+        MasterAuditContext auditContext = createAuditContext("loadMetadata", path, null, null)) {
+      if (options.isCreateAncestors()) {
+        auditContext.setSrcInode(inodePath.peekInode());
+      } else {
+        auditContext.setSrcInode(inodePath.getParentInode());
+      }
       try {
         mPermissionChecker.checkParentPermission(Mode.Bits.WRITE, inodePath);
       } catch (AccessControlException e) {

core/server/master/src/main/java/alluxio/master/file/meta/LockedInodePath.java

@@ -91,43 +91,42 @@ public synchronized  InodeFile getInodeFile() throws FileDoesNotExistException {
    * @throws InvalidPathException if the parent inode is not a directory
    * @throws FileDoesNotExistException if the parent of the target does not exist
    */
-  public synchronized  InodeDirectory getParentInodeDirectory()
+  public synchronized InodeDirectory getParentInodeDirectory()
       throws InvalidPathException, FileDoesNotExistException {
-    InodeDirectory inodeDirectory = (InodeDirectory) peekInode(false);
-    if (inodeDirectory == null) {
+    Inode inode = getParentInode();
+    if (inode == null) {
       throw new FileDoesNotExistException(
           ExceptionMessage.PATH_DOES_NOT_EXIST.getMessage(mUri.getParent()));
     }
-    return inodeDirectory;
+    if (!inode.isDirectory()) {
+      throw new InvalidPathException(
+          ExceptionMessage.PATH_MUST_HAVE_VALID_PARENT.getMessage(mUri));
+    }
+    return (InodeDirectory) inode;
+  }
+
+  /**
+   * Checks and returns the parent inode of the target inode.
+   *
+   * @return the parent of the target inode, or null if the parent does not exist
+   */
+  public synchronized Inode getParentInode() {
+    if (mPathComponents.length < 2 || mInodes.size() < (mPathComponents.length - 1)) {
+      // The path is only the root, or the list of inodes is not long enough to contain the parent
+      return null;
+    }
+    return mInodes.get(mPathComponents.length - 2);
   }
 
   /**
    * Peeks an inode on the inode path. The choice of which inode depends on whether the request
    * comes from a command with recursive flag or not.
    *
-   * @param isRecursive true if this peekInode is invoked by a command with recursive flag
-   * @return the last existing inode on the inode path if isRecursive is true, the second
-   *         last inode on the inode path if isRecursive is false
+   * @return the last existing inode on the inode path
    * @throws InvalidPathException if the parent exists but is not a directory
    */
-  public synchronized Inode peekInode(boolean isRecursive)
-      throws InvalidPathException {
-    Inode<?> inode;
-    if (!isRecursive) {
-      if (mPathComponents.length < 2 || mInodes.size() < (mPathComponents.length - 1)) {
-        // The path is only the root, or the list of inodes is not long enough to contain the parent
-        return null;
-      }
-      inode = mInodes.get(mPathComponents.length - 2);
-      if (!inode.isDirectory()) {
-        throw new InvalidPathException(
-            ExceptionMessage.PATH_MUST_HAVE_VALID_PARENT.getMessage(mUri));
-      }
-      return inode;
-    } else {
-      inode = mInodes.get(mInodes.size() - 1);
-      return inode;
-    }
+  public synchronized Inode peekInode() {
+    return mInodes.get(mInodes.size() - 1);
   }
 
   /**