8165852: (fs) Mount point not found for a file which is present in overlayfs

Summary: Check /proc/mounts when the device ID boundary is reached
Reviewed-by: alanb

src/solaris/classes/sun/nio/fs/LinuxFileStore.java

 /*
- * Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -66,6 +66,8 @@ class LinuxFileStore
         }
 
         // step 2: find mount point
+        List<UnixMountEntry> procMountsEntries =
+            fs.getMountEntries("/proc/mounts");
         UnixPath parent = path.getParent();
         while (parent != null) {
             UnixFileAttributes attrs = null;
@@ -74,16 +76,23 @@ class LinuxFileStore
             } catch (UnixException x) {
                 x.rethrowAsIOException(parent);
             }
-            if (attrs.dev() != dev())
-                break;
+            if (attrs.dev() != dev()) {
+                // step 3: lookup mounted file systems (use /proc/mounts to
+                // ensure we find the file system even when not in /etc/mtab)
+                byte[] dir = path.asByteArray();
+                for (UnixMountEntry entry : procMountsEntries) {
+                    if (Arrays.equals(dir, entry.dir()))
+                        return entry;
+                }
+            }
             path = parent;
             parent = parent.getParent();
         }
 
-        // step 3: lookup mounted file systems (use /proc/mounts to ensure we
-        // find the file system even when not in /etc/mtab)
+        // step 3: lookup mounted file systems (use /proc/mounts to
+        // ensure we find the file system even when not in /etc/mtab)
         byte[] dir = path.asByteArray();
-        for (UnixMountEntry entry: fs.getMountEntries("/proc/mounts")) {
+        for (UnixMountEntry entry : procMountsEntries) {
             if (Arrays.equals(dir, entry.dir()))
                 return entry;
         }

src/solaris/classes/sun/nio/fs/LinuxFileSystem.java

 /*
- * Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -75,7 +75,7 @@ class LinuxFileSystem extends UnixFileSystem {
     /**
      * Returns object to iterate over the mount entries in the given fstab file.
      */
-    Iterable<UnixMountEntry> getMountEntries(String fstab) {
+    List<UnixMountEntry> getMountEntries(String fstab) {
         ArrayList<UnixMountEntry> entries = new ArrayList<>();
         try {
             long fp = setmntent(Util.toBytes(fstab), Util.toBytes("r"));
@@ -101,7 +101,7 @@ class LinuxFileSystem extends UnixFileSystem {
      * Returns object to iterate over the mount entries in /etc/mtab
      */
     @Override
-    Iterable<UnixMountEntry> getMountEntries() {
+    List<UnixMountEntry> getMountEntries() {
         return getMountEntries("/etc/mtab");
     }