diff --git a/Documentation/filesystems/orangefs.txt b/Documentation/filesystems/orangefs.txt
new file mode 100644
index 0000000..64543f0
--- /dev/null
+++ b/Documentation/filesystems/orangefs.txt
@@ -0,0 +1,106 @@
+ORANGEFS
+========
+
+OrangeFS is an LGPL userspace scale-out parallel storage system. It is ideal
+for large storage problems faced by HPC, BigData, Streaming Video,
+Genomics, Bioinformatics.
+
+Orangefs, originally called PVFS, was first developed in 1993 by
+Walt Ligon and Eric Blumer as a parallel file system for Parallel
+Virtual Machine (PVM) as part of a NASA grant to study the I/O patterns
+of parallel programs.
+
+Orangefs features include:
+
+  * Distributes file data among multiple file servers
+  * Supports simultaneous access by multiple clients
+  * Stores file data and metadata on servers using local file system
+    and access methods
+  * Userspace implementation is easy to install and maintain
+  * Direct MPI support
+  * Stateless
+
+
+MAILING LIST
+============
+
+http://beowulf-underground.org/mailman/listinfo/pvfs2-users
+
+
+DOCUMENTATION
+=============
+
+http://www.orangefs.org/documentation/
+
+
+USERSPACE FILESYSTEM SOURCE
+===========================
+
+http://www.orangefs.org/downloads/LATEST/source/orangefs-2.9.0.tar.gz
+
+Orangefs versions prior to 2.9 would not be compatible with the
+upstream version of the kernel client.
+
+
+BUILDING THE USERSPACE FILESYSTEM ON A SINGLE SERVER
+====================================================
+
+When Orangefs is upstream, "--with-kernel" shouldn't be needed, but
+until then the path to where the kernel with the Orangefs kernel client
+patch was made is needed to ensure that pvfs2-client-core (the bridge
+between kernel space and user space) will build properly. You can omit
+--prefix if you don't care that things are sprinkled around in
+/usr/local.
+
+./configure --prefix=/opt/ofs --with-kernel=/path/to/orangefs/kernel
+
+make
+
+make install
+
+Create an orangefs config file:
+/opt/ofs/bin/pvfs2-genconfig /etc/pvfs2.conf
+
+  for "Enter hostnames", use the hostname, don't let it default to
+  localhost.
+
+create a pvfs2tab file in /etc:
+cat /etc/pvfs2tab
+tcp://myhostname:3334/orangefs /mymountpoint pvfs2 defaults,noauto 0 0
+
+create the mount point you specified in the tab file if needed:
+mkdir /mymountpoint
+
+bootstrap the server:
+/opt/ofs/sbin/pvfs2-server /etc/pvfs2.conf -f
+
+start the server:
+/opt/osf/sbin/pvfs2-server /etc/pvfs2.conf
+
+Now the server is running. At this point you might like to
+prove things are working with:
+
+/opt/osf/bin/pvfs2-ls /mymountpoint
+
+You might not want to enforce selinux, it doesn't seem to matter by
+linux 3.11...
+
+If stuff seems to be working, turn on the client core:
+/opt/osf/sbin/pvfs2-client -p /opt/osf/sbin/pvfs2-client-core
+
+Mount your filesystem.
+mount -t pvfs2 tcp://myhostname:3334/orangefs /mymountpoint
+
+
+OPTIONS
+=======
+
+The following mount options are accepted:
+
+  acl
+    allow the use of Access Control Lists on files and directories.
+
+  intr
+    some operations between the kernel client and the user space
+    filesystem can be interruptible, such as changes in debug levels
+    and the setting of tunable parameters.
diff --git a/fs/orangefs/dcache.c b/fs/orangefs/dcache.c
new file mode 100644
index 0000000..464cddb
--- /dev/null
+++ b/fs/orangefs/dcache.c
@@ -0,0 +1,140 @@
+/*
+ * (C) 2001 Clemson University and The University of Chicago
+ *
+ * See COPYING in top-level directory.
+ */
+
+/*
+ *  Implementation of dentry (directory cache) functions.
+ */
+
+#include "protocol.h"
+#include "pvfs2-kernel.h"
+
+/* Returns 1 if dentry can still be trusted, else 0. */
+static int pvfs2_revalidate_lookup(struct dentry *dentry)
+{
+	struct dentry *parent_dentry = dget_parent(dentry);
+	struct inode *parent_inode = parent_dentry->d_inode;
+	struct pvfs2_inode_s *parent = PVFS2_I(parent_inode);
+	struct inode *inode = dentry->d_inode;
+	struct pvfs2_kernel_op *new_op;
+	int ret = 0;
+	int err = 0;
+
+	gossip_debug(GOSSIP_DCACHE_DEBUG, "%s: attempting lookup.\n", __func__);
+
+	new_op = op_alloc(PVFS2_VFS_OP_LOOKUP);
+	if (!new_op)
+		goto out_put_parent;
+
+	new_op->upcall.req.lookup.sym_follow = PVFS2_LOOKUP_LINK_NO_FOLLOW;
+	new_op->upcall.req.lookup.parent_refn = parent->refn;
+	strncpy(new_op->upcall.req.lookup.d_name, dentry->d_name.name, PVFS2_NAME_LEN);
+
+	gossip_debug(GOSSIP_DCACHE_DEBUG,
+		     "%s:%s:%d interrupt flag [%d]\n",
+		     __FILE__,
+		     __func__,
+		     __LINE__,
+		     get_interruptible_flag(parent_inode));
+
+	err = service_operation(new_op, "pvfs2_lookup",
+			get_interruptible_flag(parent_inode));
+	if (err)
+		goto out_drop;
+
+	if (new_op->downcall.status != 0 ||
+	    !match_handle(new_op->downcall.resp.lookup.refn.khandle, inode)) {
+		gossip_debug(GOSSIP_DCACHE_DEBUG,
+			"%s:%s:%d "
+			"lookup failure |%s| or no match |%s|.\n",
+			__FILE__,
+			__func__,
+			__LINE__,
+			new_op->downcall.status ? "true" : "false",
+			match_handle(new_op->downcall.resp.lookup.refn.khandle,
+					inode) ? "false" : "true");
+		gossip_debug(GOSSIP_DCACHE_DEBUG,
+			     "%s:%s:%d revalidate failed\n",
+			     __FILE__, __func__, __LINE__);
+		goto out_drop;
+	}
+
+	ret = 1;
+out_release_op:
+	op_release(new_op);
+out_put_parent:
+	dput(parent_dentry);
+	return ret;
+out_drop:
+	d_drop(dentry);
+	goto out_release_op;
+}
+
+/*
+ * Verify that dentry is valid.
+ *
+ * Should return 1 if dentry can still be trusted, else 0
+ */
+static int pvfs2_d_revalidate(struct dentry *dentry, unsigned int flags)
+{
+	struct inode *inode;
+	int ret = 0;
+
+	if (flags & LOOKUP_RCU)
+		return -ECHILD;
+
+	gossip_debug(GOSSIP_DCACHE_DEBUG, "%s: called on dentry %p.\n",
+		     __func__, dentry);
+
+	/* find inode from dentry */
+	if (!dentry->d_inode) {
+		gossip_debug(GOSSIP_DCACHE_DEBUG, "%s: negative dentry.\n",
+			     __func__);
+		goto invalid_exit;
+	}
+
+	gossip_debug(GOSSIP_DCACHE_DEBUG, "%s: inode valid.\n", __func__);
+	inode = dentry->d_inode;
+
+	/*
+	 * first perform a lookup to make sure that the object not only
+	 * exists, but is still in the expected place in the name space
+	 */
+	if (!is_root_handle(inode)) {
+		if (!pvfs2_revalidate_lookup(dentry))
+			goto invalid_exit;
+	} else {
+		gossip_debug(GOSSIP_DCACHE_DEBUG,
+			     "%s: root handle, lookup skipped.\n",
+			     __func__);
+	}
+
+	/* now perform getattr */
+	gossip_debug(GOSSIP_DCACHE_DEBUG,
+		     "%s: doing getattr: inode: %p, handle: %pU\n",
+		     __func__,
+		     inode,
+		     get_khandle_from_ino(inode));
+	ret = pvfs2_inode_getattr(inode, PVFS_ATTR_SYS_ALL_NOHINT);
+	gossip_debug(GOSSIP_DCACHE_DEBUG,
+		     "%s: getattr %s (ret = %d), returning %s for dentry i_count=%d\n",
+		     __func__,
+		     (ret == 0 ? "succeeded" : "failed"),
+		     ret,
+		     (ret == 0 ? "valid" : "INVALID"),
+		     atomic_read(&inode->i_count));
+	if (ret != 0)
+		goto invalid_exit;
+
+	/* dentry is valid! */
+	return 1;
+
+invalid_exit:
+	return 0;
+}
+
+const struct dentry_operations pvfs2_dentry_operations = {
+	.d_revalidate = pvfs2_d_revalidate,
+};
