A workaround for RAMDISK filestore

https://discuss.elastic.co/t/elasticsearch-server-is-not-starting-on-ramdisk-imdisk/222167/2

server/src/main/java/org/elasticsearch/env/ESDummyFileStore.java

@@ -0,0 +1,91 @@
+package org.elasticsearch.env;
+
+
+import java.io.IOException;
+import java.nio.file.FileStore;
+import java.nio.file.attribute.FileAttributeView;
+import java.nio.file.attribute.FileStoreAttributeView;
+
+
+/**
+ * Dummy implementation of FileStore object.
+ * Its a workaround to handle the exception thrown from
+ * org.elasticsearch.env.Environment#getFileStore(java.nio.file.Path)
+ * when running on a RAMDISK machine or similar file system
+ *
+ */
+class ESDummyFileStore extends ESFileStore {
+
+    ESDummyFileStore(FileStore in) {
+        super(in);
+    }
+
+
+    @Override
+    public String name() {
+        return "FS_UNKNOWN_NAME";
+    }
+
+    @Override
+    public String type() {
+        return "FS_UNKNOWN_TYPE";
+    }
+
+    @Override
+    public boolean isReadOnly() {
+        return false;
+    }
+
+    @Override
+    public long getTotalSpace() throws IOException {
+        return Long.MAX_VALUE;
+    }
+
+    @Override
+    public long getUsableSpace() throws IOException {
+        return Long.MAX_VALUE;
+    }
+
+    @Override
+    public long getUnallocatedSpace() throws IOException {
+        return Long.MAX_VALUE;
+    }
+
+    @Override
+    public boolean supportsFileAttributeView(Class<? extends FileAttributeView> type) {
+        return false;
+    }
+
+    @Override
+    public boolean supportsFileAttributeView(String name) {
+        if ("lucene".equals(name)) {
+            return true;
+        } else {
+            return false;
+        }
+
+    }
+
+    @Override
+    public <V extends FileStoreAttributeView> V getFileStoreAttributeView(Class<V> type) {
+        return null;
+    }
+
+    @Override
+    public Object getAttribute(String attribute) throws IOException {
+        switch (attribute) {
+            // for the partition
+            case "lucene:major_device_number":
+                return -1;
+            case "lucene:minor_device_number":
+                return -1;
+            default:
+                return null;
+        }
+    }
+
+    @Override
+    public String toString() {
+        return "FS_UNKNOWN";
+    }
+}

server/src/main/java/org/elasticsearch/env/Environment.java

@@ -35,6 +35,7 @@
 import java.nio.file.FileStore;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.nio.file.FileSystemException;
 import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
@@ -305,7 +306,12 @@ public void validateTmpFile() throws IOException {
     }
 
     public static FileStore getFileStore(final Path path) throws IOException {
-        return new ESFileStore(Files.getFileStore(path));
+        try {
+            return new ESFileStore(Files.getFileStore(path));
+        } catch (FileSystemException ex) {
+            //A workaround for RAMDISK file system
+            return new ESDummyFileStore(null);
+        }
     }
 
     /**