kernel: backport overlayfs v11 to 3.0 and 2.6.39

Should fix whiteout issues and missing files when using extroot.

SVN-Revision: 29727

2 files changed, 2307 insertions, 1868 deletions

diff --git a/target/linux/generic/patches-2.6.39/100-overlayfs.patch b/target/linux/generic/patches-2.6.39/100-overlayfs_v11.patch
index 92bbe38298..83d74e95e2 100644
--- a/target/linux/generic/patches-2.6.39/100-overlayfs.patch
+++ b/target/linux/generic/patches-2.6.39/100-overlayfs_v11.patch
@@ -1,21 +1,283 @@
---- a/include/linux/fs.h
-+++ b/include/linux/fs.h
-@@ -1594,6 +1594,7 @@ struct inode_operations {
- 	void (*truncate_range)(struct inode *, loff_t, loff_t);
- 	int (*fiemap)(struct inode *, struct fiemap_extent_info *, u64 start,
- 		      u64 len);
-+	struct file *(*open)(struct dentry *, int flags, const struct cred *);
- } ____cacheline_aligned;
+--- /dev/null
++++ b/Documentation/filesystems/overlayfs.txt
+@@ -0,0 +1,199 @@
++Written by: Neil Brown <neilb@suse.de>
++
++Overlay Filesystem
++==================
++
++This document describes a prototype for a new approach to providing
++overlay-filesystem functionality in Linux (sometimes referred to as
++union-filesystems).  An overlay-filesystem tries to present a
++filesystem which is the result over overlaying one filesystem on top
++of the other.
++
++The result will inevitably fail to look exactly like a normal
++filesystem for various technical reasons.  The expectation is that
++many use cases will be able to ignore these differences.
++
++This approach is 'hybrid' because the objects that appear in the
++filesystem do not all appear to belong to that filesystem.  In many
++cases an object accessed in the union will be indistinguishable
++from accessing the corresponding object from the original filesystem.
++This is most obvious from the 'st_dev' field returned by stat(2).
++
++While directories will report an st_dev from the overlay-filesystem,
++all non-directory objects will report an st_dev from the lower or
++upper filesystem that is providing the object.  Similarly st_ino will
++only be unique when combined with st_dev, and both of these can change
++over the lifetime of a non-directory object.  Many applications and
++tools ignore these values and will not be affected.
++
++Upper and Lower
++---------------
++
++An overlay filesystem combines two filesystems - an 'upper' filesystem
++and a 'lower' filesystem.  When a name exists in both filesystems, the
++object in the 'upper' filesystem is visible while the object in the
++'lower' filesystem is either hidden or, in the case of directories,
++merged with the 'upper' object.
++
++It would be more correct to refer to an upper and lower 'directory
++tree' rather than 'filesystem' as it is quite possible for both
++directory trees to be in the same filesystem and there is no
++requirement that the root of a filesystem be given for either upper or
++lower.
++
++The lower filesystem can be any filesystem supported by Linux and does
++not need to be writable.  The lower filesystem can even be another
++overlayfs.  The upper filesystem will normally be writable and if it
++is it must support the creation of trusted.* extended attributes, and
++must provide valid d_type in readdir responses, at least for symbolic
++links - so NFS is not suitable.
++
++A read-only overlay of two read-only filesystems may use any
++filesystem type.
++
++Directories
++-----------
++
++Overlaying mainly involved directories.  If a given name appears in both
++upper and lower filesystems and refers to a non-directory in either,
++then the lower object is hidden - the name refers only to the upper
++object.
++
++Where both upper and lower objects are directories, a merged directory
++is formed.
++
++At mount time, the two directories given as mount options are combined
++into a merged directory:
++
++  mount -t overlayfs overlayfs -olowerdir=/lower,upperdir=/upper /overlay
++
++Then whenever a lookup is requested in such a merged directory, the
++lookup is performed in each actual directory and the combined result
++is cached in the dentry belonging to the overlay filesystem.  If both
++actual lookups find directories, both are stored and a merged
++directory is created, otherwise only one is stored: the upper if it
++exists, else the lower.
++
++Only the lists of names from directories are merged.  Other content
++such as metadata and extended attributes are reported for the upper
++directory only.  These attributes of the lower directory are hidden.
++
++whiteouts and opaque directories
++--------------------------------
++
++In order to support rm and rmdir without changing the lower
++filesystem, an overlay filesystem needs to record in the upper filesystem
++that files have been removed.  This is done using whiteouts and opaque
++directories (non-directories are always opaque).
++
++The overlay filesystem uses extended attributes with a
++"trusted.overlay."  prefix to record these details.
++
++A whiteout is created as a symbolic link with target
++"(overlay-whiteout)" and with xattr "trusted.overlay.whiteout" set to "y".
++When a whiteout is found in the upper level of a merged directory, any
++matching name in the lower level is ignored, and the whiteout itself
++is also hidden.
++
++A directory is made opaque by setting the xattr "trusted.overlay.opaque"
++to "y".  Where the upper filesystem contains an opaque directory, any
++directory in the lower filesystem with the same name is ignored.
++
++readdir
++-------
++
++When a 'readdir' request is made on a merged directory, the upper and
++lower directories are each read and the name lists merged in the
++obvious way (upper is read first, then lower - entries that already
++exist are not re-added).  This merged name list is cached in the
++'struct file' and so remains as long as the file is kept open.  If the
++directory is opened and read by two processes at the same time, they
++will each have separate caches.  A seekdir to the start of the
++directory (offset 0) followed by a readdir will cause the cache to be
++discarded and rebuilt.
++
++This means that changes to the merged directory do not appear while a
++directory is being read.  This is unlikely to be noticed by many
++programs.
++
++seek offsets are assigned sequentially when the directories are read.
++Thus if
++  - read part of a directory
++  - remember an offset, and close the directory
++  - re-open the directory some time later
++  - seek to the remembered offset
++
++there may be little correlation between the old and new locations in
++the list of filenames, particularly if anything has changed in the
++directory.
++
++Readdir on directories that are not merged is simply handled by the
++underlying directory (upper or lower).
++
++
++Non-directories
++---------------
++
++Objects that are not directories (files, symlinks, device-special
++files etc.) are presented either from the upper or lower filesystem as
++appropriate.  When a file in the lower filesystem is accessed in a way
++the requires write-access, such as opening for write access, changing
++some metadata etc., the file is first copied from the lower filesystem
++to the upper filesystem (copy_up).  Note that creating a hard-link
++also requires copy_up, though of course creation of a symlink does
++not.
++
++The copy_up may turn out to be unnecessary, for example if the file is
++opened for read-write but the data is not modified.
++
++The copy_up process first makes sure that the containing directory
++exists in the upper filesystem - creating it and any parents as
++necessary.  It then creates the object with the same metadata (owner,
++mode, mtime, symlink-target etc.) and then if the object is a file, the
++data is copied from the lower to the upper filesystem.  Finally any
++extended attributes are copied up.
++
++Once the copy_up is complete, the overlay filesystem simply
++provides direct access to the newly created file in the upper
++filesystem - future operations on the file are barely noticed by the
++overlay filesystem (though an operation on the name of the file such as
++rename or unlink will of course be noticed and handled).
++
++
++Non-standard behavior
++---------------------
++
++The copy_up operation essentially creates a new, identical file and
++moves it over to the old name.  The new file may be on a different
++filesystem, so both st_dev and st_ino of the file may change.
++
++Any open files referring to this inode will access the old data and
++metadata.  Similarly any file locks obtained before copy_up will not
++apply to the copied up file.
++
++On a file is opened with O_RDONLY fchmod(2), fchown(2), futimesat(2)
++and fsetxattr(2) will fail with EROFS.
++
++If a file with multiple hard links is copied up, then this will
++"break" the link.  Changes will not be propagated to other names
++referring to the same inode.
++
++Symlinks in /proc/PID/ and /proc/PID/fd which point to a non-directory
++object in overlayfs will not contain vaid absolute paths, only
++relative paths leading up to the filesystem's root.  This will be
++fixed in the future.
++
++Some operations are not atomic, for example a crash during copy_up or
++rename will leave the filesystem in an inconsitent state.  This will
++be addressed in the future.
++
++Changes to underlying filesystems
++---------------------------------
++
++Offline changes, when the overlay is not mounted, are allowed to either
++the upper or the lower trees.
++
++Changes to the underlying filesystems while part of a mounted overlay
++filesystem are not allowed.  If the underlying filesystem is changed,
++the behavior of the overlay is undefined, though it will not result in
++a crash or deadlock.
+--- a/MAINTAINERS
++++ b/MAINTAINERS
+@@ -4689,6 +4689,13 @@ F:	drivers/scsi/osd/
+ F:	include/scsi/osd_*
+ F:	fs/exofs/
  
- struct seq_file;
-@@ -1988,6 +1989,7 @@ extern long do_sys_open(int dfd, const c
- extern struct file *filp_open(const char *, int, int);
- extern struct file *file_open_root(struct dentry *, struct vfsmount *,
- 				   const char *, int);
-+extern struct file *vfs_open(struct path *, int flags, const struct cred *);
- extern struct file * dentry_open(struct dentry *, struct vfsmount *, int,
- 				 const struct cred *);
- extern int filp_close(struct file *, fl_owner_t id);
++OVERLAYFS FILESYSTEM
++M:	Miklos Szeredi <miklos@szeredi.hu>
++L:	linux-fsdevel@vger.kernel.org
++S:	Supported
++F:	fs/overlayfs/*
++F:	Documentation/filesystems/overlayfs.txt
++
+ P54 WIRELESS DRIVER
+ M:	Christian Lamparter <chunkeey@googlemail.com>
+ L:	linux-wireless@vger.kernel.org
+--- a/fs/Kconfig
++++ b/fs/Kconfig
+@@ -63,6 +63,7 @@ source "fs/quota/Kconfig"
+ 
+ source "fs/autofs4/Kconfig"
+ source "fs/fuse/Kconfig"
++source "fs/overlayfs/Kconfig"
+ 
+ config CUSE
+ 	tristate "Character device in Userspace support"
+--- a/fs/Makefile
++++ b/fs/Makefile
+@@ -105,6 +105,7 @@ obj-$(CONFIG_QNX4FS_FS)		+= qnx4/
+ obj-$(CONFIG_AUTOFS4_FS)	+= autofs4/
+ obj-$(CONFIG_ADFS_FS)		+= adfs/
+ obj-$(CONFIG_FUSE_FS)		+= fuse/
++obj-$(CONFIG_OVERLAYFS_FS)	+= overlayfs/
+ obj-$(CONFIG_UDF_FS)		+= udf/
+ obj-$(CONFIG_SUN_OPENPROMFS)	+= openpromfs/
+ obj-$(CONFIG_OMFS_FS)		+= omfs/
+--- a/fs/ecryptfs/main.c
++++ b/fs/ecryptfs/main.c
+@@ -594,6 +594,13 @@ static struct dentry *ecryptfs_mount(str
+ 	s->s_maxbytes = path.dentry->d_sb->s_maxbytes;
+ 	s->s_blocksize = path.dentry->d_sb->s_blocksize;
+ 	s->s_magic = ECRYPTFS_SUPER_MAGIC;
++	s->s_stack_depth = path.dentry->d_sb->s_stack_depth + 1;
++
++	rc = -EINVAL;
++	if (s->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
++		printk(KERN_ERR "eCryptfs: maximum fs stacking depth exceeded\n");
++		goto out_free;
++	}
+ 
+ 	inode = ecryptfs_get_inode(path.dentry->d_inode, s);
+ 	rc = PTR_ERR(inode);
+--- a/fs/namespace.c
++++ b/fs/namespace.c
+@@ -1494,6 +1494,23 @@ void drop_collected_mounts(struct vfsmou
+ 	release_mounts(&umount_list);
+ }
+ 
++struct vfsmount *clone_private_mount(struct path *path)
++{
++	struct vfsmount *mnt;
++
++	if (IS_MNT_UNBINDABLE(path->mnt))
++		return ERR_PTR(-EINVAL);
++
++	down_read(&namespace_sem);
++	mnt = clone_mnt(path->mnt, path->dentry, CL_PRIVATE);
++	up_read(&namespace_sem);
++	if (!mnt)
++		return ERR_PTR(-ENOMEM);
++
++	return mnt;
++}
++EXPORT_SYMBOL_GPL(clone_private_mount);
++
+ int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg,
+ 		   struct vfsmount *root)
+ {
 --- a/fs/open.c
 +++ b/fs/open.c
 @@ -666,8 +666,7 @@ static inline int __get_file_write_acces
@@ -172,903 +434,46 @@
  
  static void __put_unused_fd(struct files_struct *files, unsigned int fd)
  {
---- a/fs/splice.c
-+++ b/fs/splice.c
-@@ -1296,6 +1296,7 @@ long do_splice_direct(struct file *in, l
- 
- 	return ret;
- }
-+EXPORT_SYMBOL(do_splice_direct);
- 
- static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
- 			       struct pipe_inode_info *opipe,
---- a/fs/namespace.c
-+++ b/fs/namespace.c
-@@ -1494,6 +1494,23 @@ void drop_collected_mounts(struct vfsmou
- 	release_mounts(&umount_list);
- }
- 
-+struct vfsmount *clone_private_mount(struct path *path)
-+{
-+	struct vfsmount *mnt;
-+
-+	if (IS_MNT_UNBINDABLE(path->mnt))
-+		return ERR_PTR(-EINVAL);
-+
-+	down_read(&namespace_sem);
-+	mnt = clone_mnt(path->mnt, path->dentry, CL_PRIVATE);
-+	up_read(&namespace_sem);
-+	if (!mnt)
-+		return ERR_PTR(-ENOMEM);
-+
-+	return mnt;
-+}
-+EXPORT_SYMBOL_GPL(clone_private_mount);
+--- /dev/null
++++ b/fs/overlayfs/Kconfig
+@@ -0,0 +1,4 @@
++config OVERLAYFS_FS
++	tristate "Overlay filesystem support"
++	help
++	  Add support for overlay filesystem.
+--- /dev/null
++++ b/fs/overlayfs/Makefile
+@@ -0,0 +1,7 @@
++#
++# Makefile for the overlay filesystem.
++#
 +
- int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg,
- 		   struct vfsmount *root)
- {
---- a/include/linux/mount.h
-+++ b/include/linux/mount.h
-@@ -100,6 +100,9 @@ extern void mnt_pin(struct vfsmount *mnt
- extern void mnt_unpin(struct vfsmount *mnt);
- extern int __mnt_is_readonly(struct vfsmount *mnt);
- 
-+struct path;
-+extern struct vfsmount *clone_private_mount(struct path *path);
++obj-$(CONFIG_OVERLAYFS_FS) += overlayfs.o
 +
- extern struct vfsmount *do_kern_mount(const char *fstype, int flags,
- 				      const char *name, void *data);
- 
++overlayfs-objs := super.o inode.o dir.o readdir.o copy_up.o
 --- /dev/null
-+++ b/fs/overlayfs/overlayfs.c
-@@ -0,0 +1,2414 @@
++++ b/fs/overlayfs/copy_up.c
+@@ -0,0 +1,383 @@
++/*
++ *
++ * Copyright (C) 2011 Novell Inc.
++ *
++ * This program is free software; you can redistribute it and/or modify it
++ * under the terms of the GNU General Public License version 2 as published by
++ * the Free Software Foundation.
++ */
++
 +#include <linux/fs.h>
-+#include <linux/namei.h>
-+#include <linux/sched.h>
-+#include <linux/fs_struct.h>
++#include <linux/slab.h>
 +#include <linux/file.h>
++#include <linux/splice.h>
 +#include <linux/xattr.h>
 +#include <linux/security.h>
-+#include <linux/device_cgroup.h>
-+#include <linux/mount.h>
-+#include <linux/splice.h>
-+#include <linux/slab.h>
-+#include <linux/parser.h>
-+#include <linux/module.h>
 +#include <linux/uaccess.h>
-+#include <linux/rbtree.h>
-+
-+MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
-+MODULE_DESCRIPTION("Overlay filesystem");
-+MODULE_LICENSE("GPL");
++#include "overlayfs.h"
 +
 +#define OVL_COPY_UP_CHUNK_SIZE (1 << 20)
 +
-+struct ovl_fs {
-+	struct vfsmount *upper_mnt;
-+	struct vfsmount *lower_mnt;
-+};
-+
-+struct ovl_entry {
-+	struct dentry *__upperdentry;
-+	struct dentry *lowerdentry;
-+	union {
-+		struct {
-+			u64 version;
-+			bool opaque;
-+		};
-+		struct rcu_head rcu;
-+	};
-+};
-+
-+static const char *ovl_whiteout_xattr = "trusted.overlay.whiteout";
-+static const char *ovl_opaque_xattr = "trusted.overlay.opaque";
-+static const char *ovl_whiteout_symlink = "(overlay-whiteout)";
-+
-+enum ovl_path_type {
-+	OVL_PATH_UPPER,
-+	OVL_PATH_MERGE,
-+	OVL_PATH_LOWER,
-+};
-+
-+static enum ovl_path_type ovl_path_type(struct dentry *dentry)
-+{
-+	struct ovl_entry *oe = dentry->d_fsdata;
-+
-+	if (oe->__upperdentry) {
-+		if (oe->lowerdentry && S_ISDIR(dentry->d_inode->i_mode))
-+			return OVL_PATH_MERGE;
-+		else
-+			return OVL_PATH_UPPER;
-+	} else {
-+		return OVL_PATH_LOWER;
-+	}
-+}
-+
-+static struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe)
-+{
-+	struct dentry *upperdentry = ACCESS_ONCE(oe->__upperdentry);
-+	smp_read_barrier_depends();
-+	return upperdentry;
-+}
-+
-+static void ovl_path_upper(struct dentry *dentry, struct path *path)
-+{
-+	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
-+	struct ovl_entry *oe = dentry->d_fsdata;
-+
-+	path->mnt = ofs->upper_mnt;
-+	path->dentry = ovl_upperdentry_dereference(oe);
-+}
-+
-+static void ovl_path_lower(struct dentry *dentry, struct path *path)
-+{
-+	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
-+	struct ovl_entry *oe = dentry->d_fsdata;
-+
-+	path->mnt = ofs->lower_mnt;
-+	path->dentry = oe->lowerdentry;
-+}
-+
-+static enum ovl_path_type ovl_path_real(struct dentry *dentry,
-+					struct path *path)
-+{
-+
-+	enum ovl_path_type type = ovl_path_type(dentry);
-+
-+	if (type == OVL_PATH_LOWER)
-+		ovl_path_lower(dentry, path);
-+	else
-+		ovl_path_upper(dentry, path);
-+
-+	return type;
-+}
-+
-+static struct dentry *ovl_dentry_upper(struct dentry *dentry)
-+{
-+	struct ovl_entry *oe = dentry->d_fsdata;
-+
-+	return ovl_upperdentry_dereference(oe);
-+}
-+
-+static struct dentry *ovl_dentry_lower(struct dentry *dentry)
-+{
-+	struct ovl_entry *oe = dentry->d_fsdata;
-+
-+	return oe->lowerdentry;
-+}
-+
-+static struct dentry *ovl_dentry_real(struct dentry *dentry)
-+{
-+	struct ovl_entry *oe = dentry->d_fsdata;
-+	struct dentry *realdentry;
-+
-+	realdentry = ovl_upperdentry_dereference(oe);
-+	if (!realdentry)
-+		realdentry = oe->lowerdentry;
-+
-+	return realdentry;
-+}
-+
-+static bool ovl_dentry_is_opaque(struct dentry *dentry)
-+{
-+	struct ovl_entry *oe = dentry->d_fsdata;
-+	return oe->opaque;
-+}
-+
-+static void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque)
-+{
-+	struct ovl_entry *oe = dentry->d_fsdata;
-+	oe->opaque = opaque;
-+}
-+
-+static void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry)
-+{
-+	struct ovl_entry *oe = dentry->d_fsdata;
-+
-+	WARN_ON(!mutex_is_locked(&upperdentry->d_parent->d_inode->i_mutex));
-+	WARN_ON(oe->__upperdentry);
-+	smp_wmb();
-+	oe->__upperdentry = upperdentry;
-+}
-+
-+static void ovl_dentry_version_inc(struct dentry *dentry)
-+{
-+	struct ovl_entry *oe = dentry->d_fsdata;
-+
-+	WARN_ON(!mutex_is_locked(&dentry->d_inode->i_mutex));
-+	oe->version++;
-+}
-+
-+static u64 ovl_dentry_version_get(struct dentry *dentry)
-+{
-+	struct ovl_entry *oe = dentry->d_fsdata;
-+
-+	WARN_ON(!mutex_is_locked(&dentry->d_inode->i_mutex));
-+	return oe->version;
-+}
-+
-+static bool ovl_is_whiteout(struct dentry *dentry)
-+{
-+	int res;
-+	char val;
-+
-+	if (!dentry)
-+		return false;
-+	if (!dentry->d_inode)
-+		return false;
-+	if (!S_ISLNK(dentry->d_inode->i_mode))
-+		return false;
-+
-+	res = vfs_getxattr(dentry, ovl_whiteout_xattr, &val, 1);
-+	if (res == 1 && val == 'y')
-+		return true;
-+
-+	return false;
-+}
-+
-+static bool ovl_is_opaquedir(struct dentry *dentry)
-+{
-+	int res;
-+	char val;
-+
-+	if (!S_ISDIR(dentry->d_inode->i_mode))
-+		return false;
-+
-+	res = vfs_getxattr(dentry, ovl_opaque_xattr, &val, 1);
-+	if (res == 1 && val == 'y')
-+		return true;
-+
-+	return false;
-+}
-+
-+struct ovl_cache_entry {
-+	const char *name;
-+	unsigned int len;
-+	unsigned int type;
-+	u64 ino;
-+	bool is_whiteout;
-+	struct list_head l_node;
-+	struct rb_node node;
-+};
-+
-+struct ovl_readdir_data {
-+	struct rb_root *root;
-+	struct list_head *list;
-+	struct list_head *middle;
-+	struct dentry *dir;
-+	int count;
-+	int err;
-+};
-+
-+struct ovl_dir_file {
-+	bool is_real;
-+	bool is_cached;
-+	struct list_head cursor;
-+	u64 cache_version;
-+	struct list_head cache;
-+	struct file *realfile;
-+};
-+
-+static struct ovl_cache_entry *ovl_cache_entry_from_node(struct rb_node *n)
-+{
-+	return container_of(n, struct ovl_cache_entry, node);
-+}
-+
-+static struct ovl_cache_entry *ovl_cache_entry_find(struct rb_root *root,
-+						    const char *name, int len)
-+{
-+	struct rb_node *node = root->rb_node;
-+	int cmp;
-+
-+	while (node) {
-+		struct ovl_cache_entry *p = ovl_cache_entry_from_node(node);
-+
-+		cmp = strncmp(name, p->name, len);
-+		if (cmp > 0)
-+			node = p->node.rb_right;
-+		else if (cmp < 0 || len < p->len)
-+			node = p->node.rb_left;
-+		else
-+			return p;
-+	}
-+
-+	return NULL;
-+}
-+
-+static struct ovl_cache_entry *ovl_cache_entry_new(const char *name, int len,
-+						   u64 ino, unsigned int d_type)
-+{
-+	struct ovl_cache_entry *p;
-+
-+	p = kmalloc(sizeof(*p) + len + 1, GFP_KERNEL);
-+	if (p) {
-+		char *name_copy = (char *) (p + 1);
-+		memcpy(name_copy, name, len);
-+		name_copy[len] = '\0';
-+		p->name = name_copy;
-+		p->len = len;
-+		p->type = d_type;
-+		p->ino = ino;
-+		p->is_whiteout = false;
-+	}
-+
-+	return p;
-+}
-+
-+static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd,
-+				  const char *name, int len, u64 ino,
-+				  unsigned int d_type)
-+{
-+	struct rb_node **newp = &rdd->root->rb_node;
-+	struct rb_node *parent = NULL;
-+	struct ovl_cache_entry *p;
-+
-+	while (*newp) {
-+		int cmp;
-+		struct ovl_cache_entry *tmp;
-+
-+		parent = *newp;
-+		tmp = ovl_cache_entry_from_node(*newp);
-+		cmp = strncmp(name, tmp->name, len);
-+		if (cmp > 0)
-+			newp = &tmp->node.rb_right;
-+		else if (cmp < 0 || len < tmp->len)
-+			newp = &tmp->node.rb_left;
-+		else
-+			return 0;
-+	}
-+
-+	p = ovl_cache_entry_new(name, len, ino, d_type);
-+	if (p == NULL)
-+		return -ENOMEM;
-+
-+	list_add_tail(&p->l_node, rdd->list);
-+	rb_link_node(&p->node, parent, newp);
-+	rb_insert_color(&p->node, rdd->root);
-+
-+	return 0;
-+}
-+
-+static int ovl_fill_lower(void *buf, const char *name, int namelen,
-+			    loff_t offset, u64 ino, unsigned int d_type)
-+{
-+	struct ovl_readdir_data *rdd = buf;
-+	struct ovl_cache_entry *p;
-+
-+	rdd->count++;
-+	p = ovl_cache_entry_find(rdd->root, name, namelen);
-+	if (p) {
-+		list_move_tail(&p->l_node, rdd->middle);
-+	} else {
-+		p = ovl_cache_entry_new(name, namelen, ino, d_type);
-+		if (p == NULL)
-+			rdd->err = -ENOMEM;
-+		else
-+			list_add_tail(&p->l_node, rdd->middle);
-+	}
-+
-+	return rdd->err;
-+}
-+
-+static void ovl_cache_free(struct list_head *list)
-+{
-+	struct ovl_cache_entry *p;
-+	struct ovl_cache_entry *n;
-+
-+	list_for_each_entry_safe(p, n, list, l_node)
-+		kfree(p);
-+
-+	INIT_LIST_HEAD(list);
-+}
-+
-+static int ovl_fill_upper(void *buf, const char *name, int namelen,
-+			  loff_t offset, u64 ino, unsigned int d_type)
-+{
-+	struct ovl_readdir_data *rdd = buf;
-+
-+	rdd->count++;
-+	return ovl_cache_entry_add_rb(rdd, name, namelen, ino, d_type);
-+}
-+
-+static int ovl_dir_read(struct path *realpath, struct ovl_readdir_data *rdd,
-+			  filldir_t filler)
-+{
-+	struct file *realfile;
-+	int err;
-+
-+	realfile = vfs_open(realpath, O_RDONLY | O_DIRECTORY, current_cred());
-+	if (IS_ERR(realfile))
-+		return PTR_ERR(realfile);
-+
-+	do {
-+		rdd->count = 0;
-+		rdd->err = 0;
-+		err = vfs_readdir(realfile, filler, rdd);
-+		if (err >= 0)
-+			err = rdd->err;
-+	} while (!err && rdd->count);
-+	fput(realfile);
-+
-+	return 0;
-+}
-+
-+static void ovl_dir_reset(struct file *file)
-+{
-+	struct ovl_dir_file *od = file->private_data;
-+	enum ovl_path_type type = ovl_path_type(file->f_path.dentry);
-+
-+	if (ovl_dentry_version_get(file->f_path.dentry) != od->cache_version) {
-+		list_del_init(&od->cursor);
-+		ovl_cache_free(&od->cache);
-+		od->is_cached = false;
-+	}
-+	WARN_ON(!od->is_real && type != OVL_PATH_MERGE);
-+	if (od->is_real && type == OVL_PATH_MERGE) {
-+		fput(od->realfile);
-+		od->realfile = NULL;
-+		od->is_real = false;
-+	}
-+}
-+
-+static int ovl_dir_mark_whiteouts(struct ovl_readdir_data *rdd)
-+{
-+	struct ovl_cache_entry *p;
-+	struct dentry *dentry;
-+	const struct cred *old_cred;
-+	struct cred *override_cred;
-+
-+	override_cred = prepare_creds();
-+	if (!override_cred) {
-+		ovl_cache_free(rdd->list);
-+		return -ENOMEM;
-+	}
-+
-+	/*
-+	 * CAP_SYS_ADMIN for getxattr
-+	 * CAP_DAC_OVERRIDE for lookup
-+	 */
-+	cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
-+	cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
-+	old_cred = override_creds(override_cred);
-+
-+	mutex_lock(&rdd->dir->d_inode->i_mutex);
-+	list_for_each_entry(p, rdd->list, l_node) {
-+		if (p->type != DT_LNK)
-+			continue;
-+
-+		dentry = lookup_one_len(p->name, rdd->dir, p->len);
-+		if (IS_ERR(dentry))
-+			continue;
-+
-+		p->is_whiteout = ovl_is_whiteout(dentry);
-+		dput(dentry);
-+	}
-+	mutex_unlock(&rdd->dir->d_inode->i_mutex);
-+
-+	revert_creds(old_cred);
-+	put_cred(override_cred);
-+
-+	return 0;
-+}
-+
-+static int ovl_dir_read_merged(struct path *upperpath, struct path *lowerpath,
-+			       struct ovl_readdir_data *rdd)
-+{
-+	int err;
-+	struct rb_root root = RB_ROOT;
-+	struct list_head middle;
-+
-+	rdd->root = &root;
-+	if (upperpath->dentry) {
-+		rdd->dir = upperpath->dentry;
-+		err = ovl_dir_read(upperpath, rdd, ovl_fill_upper);
-+		if (err)
-+			goto out;
-+
-+		err = ovl_dir_mark_whiteouts(rdd);
-+		if (err)
-+			goto out;
-+	}
-+	/*
-+	 * Insert lowerpath entries before upperpath ones, this allows
-+	 * offsets to be reasonably constant
-+	 */
-+	list_add(&middle, rdd->list);
-+	rdd->middle = &middle;
-+	err = ovl_dir_read(lowerpath, rdd, ovl_fill_lower);
-+	list_del(&middle);
-+out:
-+	rdd->root = NULL;
-+
-+	return err;
-+}
-+
-+static void ovl_seek_cursor(struct ovl_dir_file *od, loff_t pos)
-+{
-+	struct list_head *l;
-+	loff_t off;
-+
-+	l = od->cache.next;
-+	for (off = 0; off < pos; off++) {
-+		if (l == &od->cache)
-+			break;
-+		l = l->next;
-+	}
-+	list_move_tail(&od->cursor, l);
-+}
-+
-+static int ovl_readdir(struct file *file, void *buf, filldir_t filler)
-+{
-+	struct ovl_dir_file *od = file->private_data;
-+	int res;
-+
-+	if (!file->f_pos)
-+		ovl_dir_reset(file);
-+
-+	if (od->is_real) {
-+		res = vfs_readdir(od->realfile, filler, buf);
-+		file->f_pos = od->realfile->f_pos;
-+
-+		return res;
-+	}
-+
-+	if (!od->is_cached) {
-+		struct path lowerpath;
-+		struct path upperpath;
-+		struct ovl_readdir_data rdd = { .list = &od->cache };
-+
-+		ovl_path_lower(file->f_path.dentry, &lowerpath);
-+		ovl_path_upper(file->f_path.dentry, &upperpath);
-+
-+		res = ovl_dir_read_merged(&upperpath, &lowerpath, &rdd);
-+		if (res) {
-+			ovl_cache_free(rdd.list);
-+			return res;
-+		}
-+
-+		od->cache_version = ovl_dentry_version_get(file->f_path.dentry);
-+		od->is_cached = true;
-+
-+		ovl_seek_cursor(od, file->f_pos);
-+	}
-+
-+	while (od->cursor.next != &od->cache) {
-+		int over;
-+		loff_t off;
-+		struct ovl_cache_entry *p;
-+
-+		p = list_entry(od->cursor.next, struct ovl_cache_entry, l_node);
-+		off = file->f_pos;
-+		file->f_pos++;
-+		list_move(&od->cursor, &p->l_node);
-+
-+		if (p->is_whiteout)
-+			continue;
-+
-+		over = filler(buf, p->name, p->len, off, p->ino, p->type);
-+		if (over)
-+			break;
-+	}
-+
-+	return 0;
-+}
-+
-+static loff_t ovl_dir_llseek(struct file *file, loff_t offset, int origin)
-+{
-+	loff_t res;
-+	struct ovl_dir_file *od = file->private_data;
-+
-+	mutex_lock(&file->f_dentry->d_inode->i_mutex);
-+	if (!file->f_pos)
-+		ovl_dir_reset(file);
-+
-+	if (od->is_real) {
-+		res = vfs_llseek(od->realfile, offset, origin);
-+		file->f_pos = od->realfile->f_pos;
-+	} else {
-+		res = -EINVAL;
-+
-+		switch (origin) {
-+		case SEEK_CUR:
-+			offset += file->f_pos;
-+			break;
-+		case SEEK_SET:
-+			break;
-+		default:
-+			goto out_unlock;
-+		}
-+		if (offset < 0)
-+			goto out_unlock;
-+
-+		if (offset != file->f_pos) {
-+			file->f_pos = offset;
-+			if (od->is_cached)
-+				ovl_seek_cursor(od, offset);
-+		}
-+		res = offset;
-+	}
-+out_unlock:
-+	mutex_unlock(&file->f_dentry->d_inode->i_mutex);
-+
-+	return res;
-+}
-+
-+static int ovl_dir_fsync(struct file *file, int datasync)
-+{
-+	struct ovl_dir_file *od = file->private_data;
-+
-+	/* May need to reopen directory if it got copied up */
-+	if (!od->realfile) {
-+		struct path upperpath;
-+
-+		ovl_path_upper(file->f_path.dentry, &upperpath);
-+		od->realfile = vfs_open(&upperpath, O_RDONLY, current_cred());
-+		if (IS_ERR(od->realfile))
-+			return PTR_ERR(od->realfile);
-+	}
-+
-+	return vfs_fsync(od->realfile, datasync);
-+}
-+
-+static int ovl_dir_release(struct inode *inode, struct file *file)
-+{
-+	struct ovl_dir_file *od = file->private_data;
-+
-+	list_del(&od->cursor);
-+	ovl_cache_free(&od->cache);
-+	if (od->realfile)
-+		fput(od->realfile);
-+	kfree(od);
-+
-+	return 0;
-+}
-+
-+static int ovl_dir_open(struct inode *inode, struct file *file)
-+{
-+	struct path realpath;
-+	struct file *realfile;
-+	struct ovl_dir_file *od;
-+	enum ovl_path_type type;
-+
-+	od = kzalloc(sizeof(struct ovl_dir_file), GFP_KERNEL);
-+	if (!od)
-+		return -ENOMEM;
-+
-+	type = ovl_path_real(file->f_path.dentry, &realpath);
-+	realfile = vfs_open(&realpath, file->f_flags, current_cred());
-+	if (IS_ERR(realfile)) {
-+		kfree(od);
-+		return PTR_ERR(realfile);
-+	}
-+	INIT_LIST_HEAD(&od->cache);
-+	INIT_LIST_HEAD(&od->cursor);
-+	od->is_cached = false;
-+	od->realfile = realfile;
-+	od->is_real = (type != OVL_PATH_MERGE);
-+	file->private_data = od;
-+
-+	return 0;
-+}
-+
-+static const struct file_operations ovl_dir_operations = {
-+	.read		= generic_read_dir,
-+	.open		= ovl_dir_open,
-+	.readdir	= ovl_readdir,
-+	.llseek		= ovl_dir_llseek,
-+	.fsync		= ovl_dir_fsync,
-+	.release	= ovl_dir_release,
-+};
-+
-+static const struct inode_operations ovl_dir_inode_operations;
-+
-+static void ovl_entry_free(struct rcu_head *head)
-+{
-+	struct ovl_entry *oe = container_of(head, struct ovl_entry, rcu);
-+	kfree(oe);
-+}
-+
-+static void ovl_dentry_release(struct dentry *dentry)
-+{
-+	struct ovl_entry *oe = dentry->d_fsdata;
-+
-+	if (oe) {
-+		dput(oe->__upperdentry);
-+		dput(oe->lowerdentry);
-+		call_rcu(&oe->rcu, ovl_entry_free);
-+	}
-+}
-+
-+static const struct dentry_operations ovl_dentry_operations = {
-+	.d_release = ovl_dentry_release,
-+};
-+
-+static struct dentry *ovl_lookup_real(struct dentry *dir, struct qstr *name)
-+{
-+	struct dentry *dentry;
-+
-+	mutex_lock(&dir->d_inode->i_mutex);
-+	dentry = lookup_one_len(name->name, dir, name->len);
-+	mutex_unlock(&dir->d_inode->i_mutex);
-+
-+	if (IS_ERR(dentry)) {
-+		if (PTR_ERR(dentry) == -ENOENT)
-+			dentry = NULL;
-+	} else if (!dentry->d_inode) {
-+		dput(dentry);
-+		dentry = NULL;
-+	}
-+	return dentry;
-+}
-+
-+static struct ovl_entry *ovl_alloc_entry(void)
-+{
-+	return kzalloc(sizeof(struct ovl_entry), GFP_KERNEL);
-+}
-+
-+static struct inode *ovl_new_inode(struct super_block *sb, umode_t mode,
-+				   struct ovl_entry *oe);
-+
-+static int ovl_whiteout(struct dentry *upperdir, struct dentry *dentry)
-+{
-+	int err;
-+	struct dentry *newdentry;
-+	const struct cred *old_cred;
-+	struct cred *override_cred;
-+
-+	/* FIXME: recheck lower dentry to see if whiteout is really needed */
-+
-+	err = -ENOMEM;
-+	override_cred = prepare_creds();
-+	if (!override_cred)
-+		goto out;
-+
-+	/*
-+	 * CAP_SYS_ADMIN for setxattr
-+	 * CAP_DAC_OVERRIDE for symlink creation
-+	 */
-+	cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
-+	cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
-+	override_cred->fsuid = 0;
-+	override_cred->fsgid = 0;
-+	old_cred = override_creds(override_cred);
-+
-+	newdentry = lookup_one_len(dentry->d_name.name, upperdir,
-+				   dentry->d_name.len);
-+	err = PTR_ERR(newdentry);
-+	if (IS_ERR(newdentry))
-+		goto out_put_cred;
-+
-+	/* Just been removed within the same locked region */
-+	WARN_ON(newdentry->d_inode);
-+
-+	err = vfs_symlink(upperdir->d_inode, newdentry, ovl_whiteout_symlink);
-+	if (err)
-+		goto out_dput;
-+
-+	ovl_dentry_version_inc(dentry->d_parent);
-+
-+	err = vfs_setxattr(newdentry, ovl_whiteout_xattr, "y", 1, 0);
-+	if (err)
-+		vfs_unlink(upperdir->d_inode, newdentry);
-+
-+out_dput:
-+	dput(newdentry);
-+out_put_cred:
-+	revert_creds(old_cred);
-+	put_cred(override_cred);
-+out:
-+	if (err) {
-+		/*
-+		 * There's no way to recover from failure to whiteout.
-+		 * What should we do?  Log a big fat error and... ?
-+		 */
-+		printk(KERN_ERR "overlayfs: ERROR - failed to whiteout '%s'\n",
-+		       dentry->d_name.name);
-+	}
-+
-+	return err;
-+}
-+
-+static struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
-+				   struct nameidata *nd)
-+{
-+	struct ovl_entry *oe;
-+	struct dentry *upperdir;
-+	struct dentry *lowerdir;
-+	struct dentry *upperdentry = NULL;
-+	struct dentry *lowerdentry = NULL;
-+	struct inode *inode = NULL;
-+	int err;
-+
-+	err = -ENOMEM;
-+	oe = ovl_alloc_entry();
-+	if (!oe)
-+		goto out;
-+
-+	upperdir = ovl_dentry_upper(dentry->d_parent);
-+	lowerdir = ovl_dentry_lower(dentry->d_parent);
-+
-+	if (upperdir) {
-+		upperdentry = ovl_lookup_real(upperdir, &dentry->d_name);
-+		err = PTR_ERR(upperdentry);
-+		if (IS_ERR(upperdentry))
-+			goto out_put_dir;
-+
-+		if (lowerdir && upperdentry &&
-+		    (S_ISLNK(upperdentry->d_inode->i_mode) ||
-+		     S_ISDIR(upperdentry->d_inode->i_mode))) {
-+			const struct cred *old_cred;
-+			struct cred *override_cred;
-+
-+			err = -ENOMEM;
-+			override_cred = prepare_creds();
-+			if (!override_cred)
-+				goto out_dput_upper;
-+
-+			/* CAP_SYS_ADMIN needed for getxattr */
-+			cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
-+			old_cred = override_creds(override_cred);
-+
-+			if (ovl_is_opaquedir(upperdentry)) {
-+				oe->opaque = true;
-+			} else if (ovl_is_whiteout(upperdentry)) {
-+				dput(upperdentry);
-+				upperdentry = NULL;
-+				oe->opaque = true;
-+			}
-+			revert_creds(old_cred);
-+			put_cred(override_cred);
-+		}
-+	}
-+	if (lowerdir && !oe->opaque) {
-+		lowerdentry = ovl_lookup_real(lowerdir, &dentry->d_name);
-+		err = PTR_ERR(lowerdentry);
-+		if (IS_ERR(lowerdentry))
-+			goto out_dput_upper;
-+	}
-+
-+	if (lowerdentry && upperdentry &&
-+	    (!S_ISDIR(upperdentry->d_inode->i_mode) ||
-+	     !S_ISDIR(lowerdentry->d_inode->i_mode))) {
-+		dput(lowerdentry);
-+		lowerdentry = NULL;
-+		oe->opaque = true;
-+	}
-+
-+	if (lowerdentry || upperdentry) {
-+		struct dentry *realdentry;
-+
-+		realdentry = upperdentry ? upperdentry : lowerdentry;
-+		err = -ENOMEM;
-+		inode = ovl_new_inode(dir->i_sb, realdentry->d_inode->i_mode, oe);
-+		if (!inode)
-+			goto out_dput;
-+	}
-+
-+	if (upperdentry)
-+		oe->__upperdentry = upperdentry;
-+
-+	if (lowerdentry)
-+		oe->lowerdentry = lowerdentry;
-+
-+	dentry->d_fsdata = oe;
-+	dentry->d_op = &ovl_dentry_operations;
-+	d_add(dentry, inode);
-+
-+	return NULL;
-+
-+out_dput:
-+	dput(lowerdentry);
-+out_dput_upper:
-+	dput(upperdentry);
-+out_put_dir:
-+	kfree(oe);
-+out:
-+	return ERR_PTR(err);
-+}
-+
 +static int ovl_copy_up_xattr(struct dentry *old, struct dentry *new)
 +{
 +	ssize_t list_size, size;
@@ -1168,120 +573,6 @@
 +	return error;
 +}
 +
-+static struct dentry *ovl_lookup_create(struct dentry *upperdir,
-+					struct dentry *template)
-+{
-+	int err;
-+	struct dentry *newdentry;
-+	struct qstr *name = &template->d_name;
-+
-+	newdentry = lookup_one_len(name->name, upperdir, name->len);
-+	if (IS_ERR(newdentry))
-+		return newdentry;
-+
-+	if (newdentry->d_inode) {
-+		const struct cred *old_cred;
-+		struct cred *override_cred;
-+
-+		/* No need to check whiteout if lower parent is non-existent */
-+		err = -EEXIST;
-+		if (!ovl_dentry_lower(template->d_parent))
-+			goto out_dput;
-+
-+		if (!S_ISLNK(newdentry->d_inode->i_mode))
-+			goto out_dput;
-+
-+		err = -ENOMEM;
-+		override_cred = prepare_creds();
-+		if (!override_cred)
-+			goto out_dput;
-+
-+		/*
-+		 * CAP_SYS_ADMIN for getxattr
-+		 * CAP_FOWNER for unlink in sticky directory
-+		 */
-+		cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
-+		cap_raise(override_cred->cap_effective, CAP_FOWNER);
-+		old_cred = override_creds(override_cred);
-+
-+		err = -EEXIST;
-+		if (ovl_is_whiteout(newdentry))
-+			err = vfs_unlink(upperdir->d_inode, newdentry);
-+
-+		revert_creds(old_cred);
-+		put_cred(override_cred);
-+		if (err)
-+			goto out_dput;
-+
-+		dput(newdentry);
-+		newdentry = lookup_one_len(name->name, upperdir, name->len);
-+		if (IS_ERR(newdentry)) {
-+			ovl_whiteout(upperdir, template);
-+			return newdentry;
-+		}
-+
-+		/*
-+		 * Whiteout just been successfully removed, parent
-+		 * i_mutex is still held, there's no way the lookup
-+		 * could return positive.
-+		 */
-+		WARN_ON(newdentry->d_inode);
-+	}
-+
-+	return newdentry;
-+
-+out_dput:
-+	dput(newdentry);
-+	return ERR_PTR(err);
-+}
-+
-+static struct dentry *ovl_upper_create(struct dentry *upperdir,
-+				       struct dentry *dentry,
-+				       struct kstat *stat, const char *link)
-+{
-+	int err;
-+	struct dentry *newdentry;
-+	struct inode *dir = upperdir->d_inode;
-+
-+	newdentry = ovl_lookup_create(upperdir, dentry);
-+	if (IS_ERR(newdentry))
-+		goto out;
-+
-+	switch (stat->mode & S_IFMT) {
-+	case S_IFREG:
-+		err = vfs_create(dir, newdentry, stat->mode, NULL);
-+		break;
-+
-+	case S_IFDIR:
-+		err = vfs_mkdir(dir, newdentry, stat->mode);
-+		break;
-+
-+	case S_IFCHR:
-+	case S_IFBLK:
-+	case S_IFIFO:
-+	case S_IFSOCK:
-+		err = vfs_mknod(dir, newdentry, stat->mode, stat->rdev);
-+		break;
-+
-+	case S_IFLNK:
-+		err = vfs_symlink(dir, newdentry, link);
-+		break;
-+
-+	default:
-+		err = -EPERM;
-+	}
-+	if (err) {
-+		if (ovl_dentry_is_opaque(dentry))
-+			ovl_whiteout(upperdir, dentry);
-+		dput(newdentry);
-+		newdentry = ERR_PTR(err);
-+	}
-+
-+out:
-+	return newdentry;
-+
-+}
-+
 +static char *ovl_read_symlink(struct dentry *realdentry)
 +{
 +	int res;
@@ -1337,46 +628,6 @@
 +	return notify_change(upperdentry, &attr);
 +}
 +
-+static int ovl_set_opaque(struct dentry *upperdentry)
-+{
-+	int err;
-+	const struct cred *old_cred;
-+	struct cred *override_cred;
-+
-+	override_cred = prepare_creds();
-+	if (!override_cred)
-+		return -ENOMEM;
-+
-+	/* CAP_SYS_ADMIN for setxattr of "trusted" namespace */
-+	cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
-+	old_cred = override_creds(override_cred);
-+	err = vfs_setxattr(upperdentry, ovl_opaque_xattr, "y", 1, 0);
-+	revert_creds(old_cred);
-+	put_cred(override_cred);
-+
-+	return err;
-+}
-+
-+static int ovl_remove_opaque(struct dentry *upperdentry)
-+{
-+	int err;
-+	const struct cred *old_cred;
-+	struct cred *override_cred;
-+
-+	override_cred = prepare_creds();
-+	if (!override_cred)
-+		return -ENOMEM;
-+
-+	/* CAP_SYS_ADMIN for removexattr of "trusted" namespace */
-+	cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
-+	old_cred = override_creds(override_cred);
-+	err = vfs_removexattr(upperdentry, ovl_opaque_xattr);
-+	revert_creds(old_cred);
-+	put_cred(override_cred);
-+
-+	return err;
-+}
-+
 +static int ovl_copy_up_locked(struct dentry *upperdir, struct dentry *dentry,
 +			      struct path *lowerpath, struct kstat *stat,
 +			      const char *link)
@@ -1384,22 +635,15 @@
 +	int err;
 +	struct path newpath;
 +	umode_t mode = stat->mode;
-+	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
 +
 +	/* Can't properly set mode on creation because of the umask */
 +	stat->mode &= S_IFMT;
 +
-+	newpath.mnt = ofs->upper_mnt;
++	ovl_path_upper(dentry, &newpath);
++	WARN_ON(newpath.dentry);
 +	newpath.dentry = ovl_upper_create(upperdir, dentry, stat, link);
-+	if (IS_ERR(newpath.dentry)) {
-+		err = PTR_ERR(newpath.dentry);
-+
-+		/* Already copied up? */
-+		if (err == -EEXIST && ovl_path_type(dentry) != OVL_PATH_LOWER)
-+			return 0;
-+
-+		return err;
-+	}
++	if (IS_ERR(newpath.dentry))
++		return PTR_ERR(newpath.dentry);
 +
 +	if (S_ISREG(stat->mode)) {
 +		err = ovl_copy_up_data(lowerpath, &newpath, stat->size);
@@ -1443,6 +687,21 @@
 +	return err;
 +}
 +
++/*
++ * Copy up a single dentry
++ *
++ * Directory renames only allowed on "pure upper" (already created on
++ * upper filesystem, never copied up).  Directories which are on lower or
++ * are merged may not be renamed.  For these -EXDEV is returned and
++ * userspace has to deal with it.  This means, when copying up a
++ * directory we can rely on it and ancestors being stable.
++ *
++ * Non-directory renames start with copy up of source if necessary.  The
++ * actual rename will only proceed once the copy up was successful.  Copy
++ * up uses upper parent i_mutex for exclusion.  Since rename can change
++ * d_parent it is possible that the copy up will lock the old parent.  At
++ * that point the file will have already been copied up anyway.
++ */
 +static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
 +			   struct path *lowerpath, struct kstat *stat)
 +{
@@ -1489,13 +748,7 @@
 +	old_cred = override_creds(override_cred);
 +
 +	mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT);
-+	/*
-+	 * Using upper filesystem locking to protect against copy up
-+	 * racing with rename (rename means the copy up was already
-+	 * successful).
-+	 */
-+	if (dentry->d_parent != parent) {
-+		WARN_ON((ovl_path_type(dentry) == OVL_PATH_LOWER));
++	if (ovl_path_type(dentry) != OVL_PATH_LOWER) {
 +		err = 0;
 +	} else {
 +		err = ovl_copy_up_locked(upperdir, dentry, lowerpath,
@@ -1518,7 +771,7 @@
 +	return err;
 +}
 +
-+static int ovl_copy_up(struct dentry *dentry)
++int ovl_copy_up(struct dentry *dentry)
 +{
 +	int err;
 +
@@ -1559,7 +812,7 @@
 +}
 +
 +/* Optimize by not copying up the file first and truncating later */
-+static int ovl_copy_up_truncate(struct dentry *dentry, loff_t size)
++int ovl_copy_up_truncate(struct dentry *dentry, loff_t size)
 +{
 +	int err;
 +	struct kstat stat;
@@ -1584,38 +837,247 @@
 +	dput(parent);
 +	return err;
 +}
+--- /dev/null
++++ b/fs/overlayfs/dir.c
+@@ -0,0 +1,596 @@
++/*
++ *
++ * Copyright (C) 2011 Novell Inc.
++ *
++ * This program is free software; you can redistribute it and/or modify it
++ * under the terms of the GNU General Public License version 2 as published by
++ * the Free Software Foundation.
++ */
++
++#include <linux/fs.h>
++#include <linux/namei.h>
++#include <linux/xattr.h>
++#include <linux/security.h>
++#include "overlayfs.h"
++
++static const char *ovl_whiteout_symlink = "(overlay-whiteout)";
 +
-+static int ovl_setattr(struct dentry *dentry, struct iattr *attr)
++static int ovl_whiteout(struct dentry *upperdir, struct dentry *dentry)
 +{
-+	struct dentry *upperdentry;
 +	int err;
++	struct dentry *newdentry;
++	const struct cred *old_cred;
++	struct cred *override_cred;
 +
-+	if ((attr->ia_valid & ATTR_SIZE) && !ovl_dentry_upper(dentry))
-+		err = ovl_copy_up_truncate(dentry, attr->ia_size);
-+	else
-+		err = ovl_copy_up(dentry);
++	/* FIXME: recheck lower dentry to see if whiteout is really needed */
++
++	err = -ENOMEM;
++	override_cred = prepare_creds();
++	if (!override_cred)
++		goto out;
++
++	/*
++	 * CAP_SYS_ADMIN for setxattr
++	 * CAP_DAC_OVERRIDE for symlink creation
++	 * CAP_FOWNER for unlink in sticky directory
++	 */
++	cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
++	cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
++	cap_raise(override_cred->cap_effective, CAP_FOWNER);
++	override_cred->fsuid = 0;
++	override_cred->fsgid = 0;
++	old_cred = override_creds(override_cred);
++
++	newdentry = lookup_one_len(dentry->d_name.name, upperdir,
++				   dentry->d_name.len);
++	err = PTR_ERR(newdentry);
++	if (IS_ERR(newdentry))
++		goto out_put_cred;
++
++	/* Just been removed within the same locked region */
++	WARN_ON(newdentry->d_inode);
++
++	err = vfs_symlink(upperdir->d_inode, newdentry, ovl_whiteout_symlink);
 +	if (err)
-+		return err;
++		goto out_dput;
 +
-+	upperdentry = ovl_dentry_upper(dentry);
++	ovl_dentry_version_inc(dentry->d_parent);
 +
-+	if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID))
-+		attr->ia_valid &= ~ATTR_MODE;
++	err = vfs_setxattr(newdentry, ovl_whiteout_xattr, "y", 1, 0);
++	if (err)
++		vfs_unlink(upperdir->d_inode, newdentry);
 +
-+	mutex_lock(&upperdentry->d_inode->i_mutex);
-+	err = notify_change(upperdentry, attr);
-+	mutex_unlock(&upperdentry->d_inode->i_mutex);
++out_dput:
++	dput(newdentry);
++out_put_cred:
++	revert_creds(old_cred);
++	put_cred(override_cred);
++out:
++	if (err) {
++		/*
++		 * There's no way to recover from failure to whiteout.
++		 * What should we do?  Log a big fat error and... ?
++		 */
++		printk(KERN_ERR "overlayfs: ERROR - failed to whiteout '%s'\n",
++		       dentry->d_name.name);
++	}
 +
 +	return err;
 +}
 +
-+static int ovl_getattr(struct vfsmount *mnt, struct dentry *dentry,
-+			 struct kstat *stat)
++static struct dentry *ovl_lookup_create(struct dentry *upperdir,
++					struct dentry *template)
 +{
-+	struct path realpath;
++	int err;
++	struct dentry *newdentry;
++	struct qstr *name = &template->d_name;
 +
-+	ovl_path_real(dentry, &realpath);
-+	return vfs_getattr(realpath.mnt, realpath.dentry, stat);
++	newdentry = lookup_one_len(name->name, upperdir, name->len);
++	if (IS_ERR(newdentry))
++		return newdentry;
++
++	if (newdentry->d_inode) {
++		const struct cred *old_cred;
++		struct cred *override_cred;
++
++		/* No need to check whiteout if lower parent is non-existent */
++		err = -EEXIST;
++		if (!ovl_dentry_lower(template->d_parent))
++			goto out_dput;
++
++		if (!S_ISLNK(newdentry->d_inode->i_mode))
++			goto out_dput;
++
++		err = -ENOMEM;
++		override_cred = prepare_creds();
++		if (!override_cred)
++			goto out_dput;
++
++		/*
++		 * CAP_SYS_ADMIN for getxattr
++		 * CAP_FOWNER for unlink in sticky directory
++		 */
++		cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
++		cap_raise(override_cred->cap_effective, CAP_FOWNER);
++		old_cred = override_creds(override_cred);
++
++		err = -EEXIST;
++		if (ovl_is_whiteout(newdentry))
++			err = vfs_unlink(upperdir->d_inode, newdentry);
++
++		revert_creds(old_cred);
++		put_cred(override_cred);
++		if (err)
++			goto out_dput;
++
++		dput(newdentry);
++		newdentry = lookup_one_len(name->name, upperdir, name->len);
++		if (IS_ERR(newdentry)) {
++			ovl_whiteout(upperdir, template);
++			return newdentry;
++		}
++
++		/*
++		 * Whiteout just been successfully removed, parent
++		 * i_mutex is still held, there's no way the lookup
++		 * could return positive.
++		 */
++		WARN_ON(newdentry->d_inode);
++	}
++
++	return newdentry;
++
++out_dput:
++	dput(newdentry);
++	return ERR_PTR(err);
++}
++
++struct dentry *ovl_upper_create(struct dentry *upperdir, struct dentry *dentry,
++				struct kstat *stat, const char *link)
++{
++	int err;
++	struct dentry *newdentry;
++	struct inode *dir = upperdir->d_inode;
++
++	newdentry = ovl_lookup_create(upperdir, dentry);
++	if (IS_ERR(newdentry))
++		goto out;
++
++	switch (stat->mode & S_IFMT) {
++	case S_IFREG:
++		err = vfs_create(dir, newdentry, stat->mode, NULL);
++		break;
++
++	case S_IFDIR:
++		err = vfs_mkdir(dir, newdentry, stat->mode);
++		break;
++
++	case S_IFCHR:
++	case S_IFBLK:
++	case S_IFIFO:
++	case S_IFSOCK:
++		err = vfs_mknod(dir, newdentry, stat->mode, stat->rdev);
++		break;
++
++	case S_IFLNK:
++		err = vfs_symlink(dir, newdentry, link);
++		break;
++
++	default:
++		err = -EPERM;
++	}
++	if (err) {
++		if (ovl_dentry_is_opaque(dentry))
++			ovl_whiteout(upperdir, dentry);
++		dput(newdentry);
++		newdentry = ERR_PTR(err);
++	} else if (WARN_ON(!newdentry->d_inode)) {
++		/*
++		 * Not quite sure if non-instantiated dentry is legal or not.
++		 * VFS doesn't seem to care so check and warn here.
++		 */
++		dput(newdentry);
++		newdentry = ERR_PTR(-ENOENT);
++	}
++
++out:
++	return newdentry;
++
++}
++
++static int ovl_set_opaque(struct dentry *upperdentry)
++{
++	int err;
++	const struct cred *old_cred;
++	struct cred *override_cred;
++
++	override_cred = prepare_creds();
++	if (!override_cred)
++		return -ENOMEM;
++
++	/* CAP_SYS_ADMIN for setxattr of "trusted" namespace */
++	cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
++	old_cred = override_creds(override_cred);
++	err = vfs_setxattr(upperdentry, ovl_opaque_xattr, "y", 1, 0);
++	revert_creds(old_cred);
++	put_cred(override_cred);
++
++	return err;
++}
++
++static int ovl_remove_opaque(struct dentry *upperdentry)
++{
++	int err;
++	const struct cred *old_cred;
++	struct cred *override_cred;
++
++	override_cred = prepare_creds();
++	if (!override_cred)
++		return -ENOMEM;
++
++	/* CAP_SYS_ADMIN for removexattr of "trusted" namespace */
++	cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
++	old_cred = override_creds(override_cred);
++	err = vfs_removexattr(upperdentry, ovl_opaque_xattr);
++	revert_creds(old_cred);
++	put_cred(override_cred);
++
++	return err;
 +}
 +
 +static int ovl_dir_getattr(struct vfsmount *mnt, struct dentry *dentry,
@@ -1644,79 +1106,6 @@
 +	return 0;
 +}
 +
-+static int ovl_permission(struct inode *inode, int mask, unsigned int flags)
-+{
-+	struct ovl_entry *oe;
-+	struct dentry *alias = NULL;
-+	struct inode *realinode;
-+	struct dentry *realdentry;
-+	bool is_upper;
-+	int err;
-+
-+	if (S_ISDIR(inode->i_mode)) {
-+		oe = inode->i_private;
-+	} else if (flags & IPERM_FLAG_RCU) {
-+		return -ECHILD;
-+	} else {
-+		/*
-+		 * For non-directories find an alias and get the info
-+		 * from there.
-+		 */
-+		spin_lock(&inode->i_lock);
-+		if (WARN_ON(list_empty(&inode->i_dentry))) {
-+			spin_unlock(&inode->i_lock);
-+			return -ENOENT;
-+		}
-+		alias = list_entry(inode->i_dentry.next, struct dentry, d_alias);
-+		dget(alias);
-+		spin_unlock(&inode->i_lock);
-+		oe = alias->d_fsdata;
-+	}
-+
-+	realdentry = ovl_upperdentry_dereference(oe);
-+	is_upper = true;
-+	if (!realdentry) {
-+		realdentry = oe->lowerdentry;
-+		is_upper = false;
-+	}
-+
-+	/* Careful in RCU walk mode */
-+	realinode = ACCESS_ONCE(realdentry->d_inode);
-+	if (!realinode) {
-+		WARN_ON(!(flags & IPERM_FLAG_RCU));
-+		return -ENOENT;
-+	}
-+
-+	if (mask & MAY_WRITE) {
-+		umode_t mode = realinode->i_mode;
-+
-+		/*
-+		 * Writes will always be redirected to upper layer, so
-+		 * ignore lower layer being read-only.
-+		 */
-+		err = -EROFS;
-+		if (is_upper && IS_RDONLY(realinode) &&
-+		    (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
-+			goto out_dput;
-+
-+		/*
-+		 * Nobody gets write access to an immutable file.
-+		 */
-+		err = -EACCES;
-+		if (IS_IMMUTABLE(realinode))
-+			goto out_dput;
-+	}
-+
-+	if (realinode->i_op->permission)
-+		err = realinode->i_op->permission(realinode, mask, flags);
-+	else
-+		err = generic_permission(realinode, mask, flags,
-+					 realinode->i_op->check_acl);
-+out_dput:
-+	dput(alias);
-+	return err;
-+}
-+
 +static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
 +			     const char *link)
 +{
@@ -1794,73 +1183,6 @@
 +	return ovl_create_object(dentry, S_IFLNK, 0, link);
 +}
 +
-+struct ovl_link_data {
-+	struct dentry *realdentry;
-+	void *cookie;
-+};
-+
-+static void *ovl_follow_link(struct dentry *dentry, struct nameidata *nd)
-+{
-+	void *ret;
-+	struct dentry *realdentry;
-+	struct inode *realinode;
-+
-+	realdentry = ovl_dentry_real(dentry);
-+	realinode = realdentry->d_inode;
-+
-+	if (WARN_ON(!realinode->i_op->follow_link))
-+		return ERR_PTR(-EPERM);
-+
-+	ret = realinode->i_op->follow_link(realdentry, nd);
-+	if (IS_ERR(ret))
-+		return ret;
-+
-+	if (realinode->i_op->put_link) {
-+		struct ovl_link_data *data;
-+
-+		data = kmalloc(sizeof(struct ovl_link_data), GFP_KERNEL);
-+		if (!data) {
-+			realinode->i_op->put_link(realdentry, nd, ret);
-+			return ERR_PTR(-ENOMEM);
-+		}
-+		data->realdentry = realdentry;
-+		data->cookie = ret;
-+
-+		return data;
-+	} else {
-+		return NULL;
-+	}
-+}
-+
-+static void ovl_put_link(struct dentry *dentry, struct nameidata *nd, void *c)
-+{
-+	struct inode *realinode;
-+	struct ovl_link_data *data = c;
-+
-+	if (!data)
-+		return;
-+
-+	realinode = data->realdentry->d_inode;
-+	realinode->i_op->put_link(data->realdentry, nd, data->cookie);
-+	kfree(data);
-+}
-+
-+static int ovl_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
-+{
-+	struct path realpath;
-+	struct inode *realinode;
-+
-+	ovl_path_real(dentry, &realpath);
-+	realinode = realpath.dentry->d_inode;
-+
-+	if (!realinode->i_op->readlink)
-+		return -EINVAL;
-+
-+	touch_atime(realpath.mnt, realpath.dentry);
-+
-+	return realinode->i_op->readlink(realpath.dentry, buf, bufsiz);
-+}
-+
 +static int ovl_do_remove(struct dentry *dentry, bool is_dir)
 +{
 +	int err;
@@ -1880,6 +1202,8 @@
 +		if (realpath.dentry->d_parent != upperdir)
 +			goto out_d_drop;
 +
++		/* FIXME: create whiteout up front and rename to target */
++
 +		if (is_dir)
 +			err = vfs_rmdir(upperdir->d_inode, realpath.dentry);
 +		else
@@ -1911,100 +1235,6 @@
 +	return ovl_do_remove(dentry, false);
 +}
 +
-+static int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list)
-+{
-+	int err;
-+	struct path lowerpath;
-+	struct path upperpath;
-+	struct ovl_cache_entry *p;
-+	struct ovl_readdir_data rdd = { .list = list };
-+
-+	ovl_path_upper(dentry, &upperpath);
-+	ovl_path_lower(dentry, &lowerpath);
-+
-+	err = ovl_dir_read_merged(&upperpath, &lowerpath, &rdd);
-+	if (err)
-+		return err;
-+
-+	err = 0;
-+
-+	list_for_each_entry(p, list, l_node) {
-+		if (p->is_whiteout)
-+			continue;
-+
-+		if (p->name[0] == '.') {
-+			if (p->len == 1)
-+				continue;
-+			if (p->len == 2 && p->name[1] == '.')
-+				continue;
-+		}
-+		err = -ENOTEMPTY;
-+		break;
-+	}
-+
-+	return err;
-+}
-+
-+static int ovl_remove_whiteouts(struct dentry *dir, struct list_head *list)
-+{
-+	struct path upperpath;
-+	struct dentry *upperdir;
-+	struct ovl_cache_entry *p;
-+	const struct cred *old_cred;
-+	struct cred *override_cred;
-+	int ret = 0;
-+
-+	ovl_path_upper(dir, &upperpath);
-+	upperdir = upperpath.dentry;
-+
-+	override_cred = prepare_creds();
-+	if (!override_cred)
-+		return -ENOMEM;
-+
-+	/*
-+	 * CAP_DAC_OVERRIDE for lookup and unlink
-+	 */
-+	cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
-+	old_cred = override_creds(override_cred);
-+
-+	mutex_lock(&upperdir->d_inode->i_mutex);
-+	list_for_each_entry(p, list, l_node) {
-+		if (p->is_whiteout) {
-+			struct dentry *dentry;
-+
-+			dentry = lookup_one_len(p->name, upperdir, p->len);
-+			if (IS_ERR(dentry)) {
-+				ret = PTR_ERR(dentry);
-+				break;
-+			}
-+			ret = vfs_unlink(upperdir->d_inode, dentry);
-+			dput(dentry);
-+			if (ret)
-+				break;
-+		}
-+	}
-+	mutex_unlock(&upperdir->d_inode->i_mutex);
-+
-+	revert_creds(old_cred);
-+	put_cred(override_cred);
-+
-+	return ret;
-+}
-+
-+static int ovl_check_empty_and_clear(struct dentry *dentry,
-+				     enum ovl_path_type type)
-+{
-+	int err;
-+	LIST_HEAD(list);
-+
-+	err = ovl_check_empty_dir(dentry, &list);
-+	if (!err && type == OVL_PATH_MERGE)
-+		err = ovl_remove_whiteouts(dentry, &list);
-+
-+	ovl_cache_free(&list);
-+
-+	return err;
-+}
 +
 +static int ovl_rmdir(struct inode *dir, struct dentry *dentry)
 +{
@@ -2047,6 +1277,12 @@
 +	olddentry = ovl_dentry_upper(old);
 +	err = vfs_link(olddentry, upperdir->d_inode, newdentry);
 +	if (!err) {
++		if (WARN_ON(!newdentry->d_inode)) {
++			dput(newdentry);
++			err = -ENOENT;
++			goto out_unlock;
++		}
++
 +		ovl_dentry_version_inc(new->d_parent);
 +		ovl_dentry_update(new, newdentry);
 +
@@ -2069,6 +1305,7 @@
 +{
 +	int err;
 +	enum ovl_path_type old_type;
++	enum ovl_path_type new_type;
 +	struct dentry *old_upperdir;
 +	struct dentry *new_upperdir;
 +	struct dentry *olddentry;
@@ -2076,6 +1313,7 @@
 +	struct dentry *trap;
 +	bool old_opaque;
 +	bool new_opaque;
++	bool new_create = false;
 +	bool is_dir = S_ISDIR(old->d_inode->i_mode);
 +
 +	/* Don't copy up directory trees */
@@ -2084,8 +1322,6 @@
 +		return -EXDEV;
 +
 +	if (new->d_inode) {
-+		enum ovl_path_type new_type;
-+
 +		new_type = ovl_path_type(new);
 +
 +		if (new_type == OVL_PATH_LOWER && old_type == OVL_PATH_LOWER) {
@@ -2105,6 +1341,8 @@
 +			if (err)
 +				return err;
 +		}
++	} else {
++		new_type = OVL_PATH_UPPER;
 +	}
 +
 +	err = ovl_copy_up(old);
@@ -2125,6 +1363,7 @@
 +	if (newdentry) {
 +		dget(newdentry);
 +	} else {
++		new_create = true;
 +		newdentry = ovl_lookup_create(new_upperdir, new);
 +		err = PTR_ERR(newdentry);
 +		if (IS_ERR(newdentry))
@@ -2142,8 +1381,7 @@
 +		goto out_dput;
 +
 +	old_opaque = ovl_dentry_is_opaque(old);
-+	new_opaque = ovl_dentry_is_opaque(new) ||
-+		ovl_path_type(new) != OVL_PATH_UPPER;
++	new_opaque = ovl_dentry_is_opaque(new) || new_type != OVL_PATH_UPPER;
 +
 +	if (is_dir && !old_opaque && new_opaque) {
 +		err = ovl_set_opaque(olddentry);
@@ -2155,7 +1393,7 @@
 +			 new_upperdir->d_inode, newdentry);
 +
 +	if (err) {
-+		if (ovl_dentry_is_opaque(new))
++		if (new_create && ovl_dentry_is_opaque(new))
 +			ovl_whiteout(new_upperdir, new);
 +		if (is_dir && !old_opaque && new_opaque)
 +			ovl_remove_opaque(olddentry);
@@ -2180,13 +1418,228 @@
 +	return err;
 +}
 +
++const struct inode_operations ovl_dir_inode_operations = {
++	.lookup		= ovl_lookup,
++	.mkdir		= ovl_mkdir,
++	.symlink	= ovl_symlink,
++	.unlink		= ovl_unlink,
++	.rmdir		= ovl_rmdir,
++	.rename		= ovl_rename,
++	.link		= ovl_link,
++	.setattr	= ovl_setattr,
++	.create		= ovl_create,
++	.mknod		= ovl_mknod,
++	.permission	= ovl_permission,
++	.getattr	= ovl_dir_getattr,
++	.setxattr	= ovl_setxattr,
++	.getxattr	= ovl_getxattr,
++	.listxattr	= ovl_listxattr,
++	.removexattr	= ovl_removexattr,
++};
+--- /dev/null
++++ b/fs/overlayfs/inode.c
+@@ -0,0 +1,384 @@
++/*
++ *
++ * Copyright (C) 2011 Novell Inc.
++ *
++ * This program is free software; you can redistribute it and/or modify it
++ * under the terms of the GNU General Public License version 2 as published by
++ * the Free Software Foundation.
++ */
++
++#include <linux/fs.h>
++#include <linux/slab.h>
++#include <linux/xattr.h>
++#include "overlayfs.h"
++
++int ovl_setattr(struct dentry *dentry, struct iattr *attr)
++{
++	struct dentry *upperdentry;
++	int err;
++
++	if ((attr->ia_valid & ATTR_SIZE) && !ovl_dentry_upper(dentry))
++		err = ovl_copy_up_truncate(dentry, attr->ia_size);
++	else
++		err = ovl_copy_up(dentry);
++	if (err)
++		return err;
++
++	upperdentry = ovl_dentry_upper(dentry);
++
++	if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID))
++		attr->ia_valid &= ~ATTR_MODE;
++
++	mutex_lock(&upperdentry->d_inode->i_mutex);
++	err = notify_change(upperdentry, attr);
++	mutex_unlock(&upperdentry->d_inode->i_mutex);
++
++	return err;
++}
++
++static int ovl_getattr(struct vfsmount *mnt, struct dentry *dentry,
++			 struct kstat *stat)
++{
++	struct path realpath;
++
++	ovl_path_real(dentry, &realpath);
++	return vfs_getattr(realpath.mnt, realpath.dentry, stat);
++}
++
++int ovl_permission(struct inode *inode, int mask, unsigned int flags)
++{
++	struct ovl_entry *oe;
++	struct dentry *alias = NULL;
++	struct inode *realinode;
++	struct dentry *realdentry;
++	bool is_upper;
++	int err;
++
++	if (S_ISDIR(inode->i_mode)) {
++		oe = inode->i_private;
++	} else if (flags & IPERM_FLAG_RCU) {
++		return -ECHILD;
++	} else {
++		/*
++		 * For non-directories find an alias and get the info
++		 * from there.
++		 */
++		spin_lock(&inode->i_lock);
++		if (WARN_ON(list_empty(&inode->i_dentry))) {
++			spin_unlock(&inode->i_lock);
++			return -ENOENT;
++		}
++		alias = list_entry(inode->i_dentry.next, struct dentry, d_alias);
++		dget(alias);
++		spin_unlock(&inode->i_lock);
++		oe = alias->d_fsdata;
++	}
++
++	realdentry = ovl_entry_real(oe, &is_upper);
++
++	/* Careful in RCU walk mode */
++	realinode = ACCESS_ONCE(realdentry->d_inode);
++	if (!realinode) {
++		WARN_ON(!(flags & IPERM_FLAG_RCU));
++		err = -ENOENT;
++		goto out_dput;
++	}
++
++	if (mask & MAY_WRITE) {
++		umode_t mode = realinode->i_mode;
++
++		/*
++		 * Writes will always be redirected to upper layer, so
++		 * ignore lower layer being read-only.
++		 *
++		 * If the overlay itself is read-only then proceed
++		 * with the permission check, don't return EROFS.
++		 * This will only happen if this is the lower layer of
++		 * another overlayfs.
++		 *
++		 * If upper fs becomes read-only after the overlay was
++		 * constructed return EROFS to prevent modification of
++		 * upper layer.
++		 */
++		err = -EROFS;
++		if (is_upper && !IS_RDONLY(inode) && IS_RDONLY(realinode) &&
++		    (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
++			goto out_dput;
++
++		/*
++		 * Nobody gets write access to an immutable file.
++		 */
++		err = -EACCES;
++		if (IS_IMMUTABLE(realinode))
++			goto out_dput;
++	}
++
++	if (realinode->i_op->permission)
++		err = realinode->i_op->permission(realinode, mask, flags);
++	else
++		err = generic_permission(realinode, mask, flags,
++					 realinode->i_op->check_acl);
++out_dput:
++	dput(alias);
++	return err;
++}
++
++
++struct ovl_link_data {
++	struct dentry *realdentry;
++	void *cookie;
++};
++
++static void *ovl_follow_link(struct dentry *dentry, struct nameidata *nd)
++{
++	void *ret;
++	struct dentry *realdentry;
++	struct inode *realinode;
++
++	realdentry = ovl_dentry_real(dentry);
++	realinode = realdentry->d_inode;
++
++	if (WARN_ON(!realinode->i_op->follow_link))
++		return ERR_PTR(-EPERM);
++
++	ret = realinode->i_op->follow_link(realdentry, nd);
++	if (IS_ERR(ret))
++		return ret;
++
++	if (realinode->i_op->put_link) {
++		struct ovl_link_data *data;
++
++		data = kmalloc(sizeof(struct ovl_link_data), GFP_KERNEL);
++		if (!data) {
++			realinode->i_op->put_link(realdentry, nd, ret);
++			return ERR_PTR(-ENOMEM);
++		}
++		data->realdentry = realdentry;
++		data->cookie = ret;
++
++		return data;
++	} else {
++		return NULL;
++	}
++}
++
++static void ovl_put_link(struct dentry *dentry, struct nameidata *nd, void *c)
++{
++	struct inode *realinode;
++	struct ovl_link_data *data = c;
++
++	if (!data)
++		return;
++
++	realinode = data->realdentry->d_inode;
++	realinode->i_op->put_link(data->realdentry, nd, data->cookie);
++	kfree(data);
++}
++
++static int ovl_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
++{
++	struct path realpath;
++	struct inode *realinode;
++
++	ovl_path_real(dentry, &realpath);
++	realinode = realpath.dentry->d_inode;
++
++	if (!realinode->i_op->readlink)
++		return -EINVAL;
++
++	touch_atime(realpath.mnt, realpath.dentry);
++
++	return realinode->i_op->readlink(realpath.dentry, buf, bufsiz);
++}
++
++
 +static bool ovl_is_private_xattr(const char *name)
 +{
 +	return strncmp(name, "trusted.overlay.", 14) == 0;
 +}
 +
-+static int ovl_setxattr(struct dentry *dentry, const char *name,
-+			  const void *value, size_t size, int flags)
++int ovl_setxattr(struct dentry *dentry, const char *name,
++		 const void *value, size_t size, int flags)
 +{
 +	int err;
 +	struct dentry *upperdentry;
@@ -2202,8 +1655,8 @@
 +	return  vfs_setxattr(upperdentry, name, value, size, flags);
 +}
 +
-+static ssize_t ovl_getxattr(struct dentry *dentry, const char *name,
-+			      void *value, size_t size)
++ssize_t ovl_getxattr(struct dentry *dentry, const char *name,
++		     void *value, size_t size)
 +{
 +	if (ovl_path_type(dentry->d_parent) == OVL_PATH_MERGE &&
 +	    ovl_is_private_xattr(name))
@@ -2212,7 +1665,7 @@
 +	return vfs_getxattr(ovl_dentry_real(dentry), name, value, size);
 +}
 +
-+static ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
++ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
 +{
 +	ssize_t res;
 +	int off;
@@ -2242,7 +1695,7 @@
 +	return res;
 +}
 +
-+static int ovl_removexattr(struct dentry *dentry, const char *name)
++int ovl_removexattr(struct dentry *dentry, const char *name)
 +{
 +	int err;
 +	struct path realpath;
@@ -2305,25 +1758,6 @@
 +	return vfs_open(&realpath, flags, cred);
 +}
 +
-+static const struct inode_operations ovl_dir_inode_operations = {
-+	.lookup		= ovl_lookup,
-+	.mkdir		= ovl_mkdir,
-+	.symlink	= ovl_symlink,
-+	.unlink		= ovl_unlink,
-+	.rmdir		= ovl_rmdir,
-+	.rename		= ovl_rename,
-+	.link		= ovl_link,
-+	.setattr	= ovl_setattr,
-+	.create		= ovl_create,
-+	.mknod		= ovl_mknod,
-+	.permission	= ovl_permission,
-+	.getattr	= ovl_dir_getattr,
-+	.setxattr	= ovl_setxattr,
-+	.getxattr	= ovl_getxattr,
-+	.listxattr	= ovl_listxattr,
-+	.removexattr	= ovl_removexattr,
-+};
-+
 +static const struct inode_operations ovl_file_inode_operations = {
 +	.setattr	= ovl_setattr,
 +	.permission	= ovl_permission,
@@ -2347,8 +1781,8 @@
 +	.removexattr	= ovl_removexattr,
 +};
 +
-+static struct inode *ovl_new_inode(struct super_block *sb, umode_t mode,
-+				   struct ovl_entry *oe)
++struct inode *ovl_new_inode(struct super_block *sb, umode_t mode,
++			    struct ovl_entry *oe)
 +{
 +	struct inode *inode;
 +
@@ -2389,6 +1823,1011 @@
 +	return inode;
 +
 +}
+--- /dev/null
++++ b/fs/overlayfs/overlayfs.h
+@@ -0,0 +1,63 @@
++/*
++ *
++ * Copyright (C) 2011 Novell Inc.
++ *
++ * This program is free software; you can redistribute it and/or modify it
++ * under the terms of the GNU General Public License version 2 as published by
++ * the Free Software Foundation.
++ */
++
++struct ovl_entry;
++
++enum ovl_path_type {
++	OVL_PATH_UPPER,
++	OVL_PATH_MERGE,
++	OVL_PATH_LOWER,
++};
++
++extern const char *ovl_opaque_xattr;
++extern const char *ovl_whiteout_xattr;
++extern const struct dentry_operations ovl_dentry_operations;
++
++enum ovl_path_type ovl_path_type(struct dentry *dentry);
++u64 ovl_dentry_version_get(struct dentry *dentry);
++void ovl_dentry_version_inc(struct dentry *dentry);
++void ovl_path_upper(struct dentry *dentry, struct path *path);
++void ovl_path_lower(struct dentry *dentry, struct path *path);
++enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);
++struct dentry *ovl_dentry_upper(struct dentry *dentry);
++struct dentry *ovl_dentry_lower(struct dentry *dentry);
++struct dentry *ovl_dentry_real(struct dentry *dentry);
++struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper);
++bool ovl_dentry_is_opaque(struct dentry *dentry);
++void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque);
++bool ovl_is_whiteout(struct dentry *dentry);
++void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry);
++struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
++			  struct nameidata *nd);
++
++struct dentry *ovl_upper_create(struct dentry *upperdir, struct dentry *dentry,
++				struct kstat *stat, const char *link);
++
++/* readdir.c */
++extern const struct file_operations ovl_dir_operations;
++int ovl_check_empty_and_clear(struct dentry *dentry, enum ovl_path_type type);
++
++/* inode.c */
++int ovl_setattr(struct dentry *dentry, struct iattr *attr);
++int ovl_permission(struct inode *inode, int mask, unsigned int flags);
++int ovl_setxattr(struct dentry *dentry, const char *name,
++		 const void *value, size_t size, int flags);
++ssize_t ovl_getxattr(struct dentry *dentry, const char *name,
++		     void *value, size_t size);
++ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size);
++int ovl_removexattr(struct dentry *dentry, const char *name);
++
++struct inode *ovl_new_inode(struct super_block *sb, umode_t mode,
++			    struct ovl_entry *oe);
++/* dir.c */
++extern const struct inode_operations ovl_dir_inode_operations;
++
++/* copy_up.c */
++int ovl_copy_up(struct dentry *dentry);
++int ovl_copy_up_truncate(struct dentry *dentry, loff_t size);
+--- /dev/null
++++ b/fs/overlayfs/readdir.c
+@@ -0,0 +1,558 @@
++/*
++ *
++ * Copyright (C) 2011 Novell Inc.
++ *
++ * This program is free software; you can redistribute it and/or modify it
++ * under the terms of the GNU General Public License version 2 as published by
++ * the Free Software Foundation.
++ */
++
++#include <linux/fs.h>
++#include <linux/slab.h>
++#include <linux/namei.h>
++#include <linux/file.h>
++#include <linux/xattr.h>
++#include <linux/rbtree.h>
++#include <linux/security.h>
++#include "overlayfs.h"
++
++struct ovl_cache_entry {
++	const char *name;
++	unsigned int len;
++	unsigned int type;
++	u64 ino;
++	bool is_whiteout;
++	struct list_head l_node;
++	struct rb_node node;
++};
++
++struct ovl_readdir_data {
++	struct rb_root *root;
++	struct list_head *list;
++	struct list_head *middle;
++	struct dentry *dir;
++	int count;
++	int err;
++};
++
++struct ovl_dir_file {
++	bool is_real;
++	bool is_cached;
++	struct list_head cursor;
++	u64 cache_version;
++	struct list_head cache;
++	struct file *realfile;
++};
++
++static struct ovl_cache_entry *ovl_cache_entry_from_node(struct rb_node *n)
++{
++	return container_of(n, struct ovl_cache_entry, node);
++}
++
++static struct ovl_cache_entry *ovl_cache_entry_find(struct rb_root *root,
++						    const char *name, int len)
++{
++	struct rb_node *node = root->rb_node;
++	int cmp;
++
++	while (node) {
++		struct ovl_cache_entry *p = ovl_cache_entry_from_node(node);
++
++		cmp = strncmp(name, p->name, len);
++		if (cmp > 0)
++			node = p->node.rb_right;
++		else if (cmp < 0 || len < p->len)
++			node = p->node.rb_left;
++		else
++			return p;
++	}
++
++	return NULL;
++}
++
++static struct ovl_cache_entry *ovl_cache_entry_new(const char *name, int len,
++						   u64 ino, unsigned int d_type)
++{
++	struct ovl_cache_entry *p;
++
++	p = kmalloc(sizeof(*p) + len + 1, GFP_KERNEL);
++	if (p) {
++		char *name_copy = (char *) (p + 1);
++		memcpy(name_copy, name, len);
++		name_copy[len] = '\0';
++		p->name = name_copy;
++		p->len = len;
++		p->type = d_type;
++		p->ino = ino;
++		p->is_whiteout = false;
++	}
++
++	return p;
++}
++
++static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd,
++				  const char *name, int len, u64 ino,
++				  unsigned int d_type)
++{
++	struct rb_node **newp = &rdd->root->rb_node;
++	struct rb_node *parent = NULL;
++	struct ovl_cache_entry *p;
++
++	while (*newp) {
++		int cmp;
++		struct ovl_cache_entry *tmp;
++
++		parent = *newp;
++		tmp = ovl_cache_entry_from_node(*newp);
++		cmp = strncmp(name, tmp->name, len);
++		if (cmp > 0)
++			newp = &tmp->node.rb_right;
++		else if (cmp < 0 || len < tmp->len)
++			newp = &tmp->node.rb_left;
++		else
++			return 0;
++	}
++
++	p = ovl_cache_entry_new(name, len, ino, d_type);
++	if (p == NULL)
++		return -ENOMEM;
++
++	list_add_tail(&p->l_node, rdd->list);
++	rb_link_node(&p->node, parent, newp);
++	rb_insert_color(&p->node, rdd->root);
++
++	return 0;
++}
++
++static int ovl_fill_lower(void *buf, const char *name, int namelen,
++			    loff_t offset, u64 ino, unsigned int d_type)
++{
++	struct ovl_readdir_data *rdd = buf;
++	struct ovl_cache_entry *p;
++
++	rdd->count++;
++	p = ovl_cache_entry_find(rdd->root, name, namelen);
++	if (p) {
++		list_move_tail(&p->l_node, rdd->middle);
++	} else {
++		p = ovl_cache_entry_new(name, namelen, ino, d_type);
++		if (p == NULL)
++			rdd->err = -ENOMEM;
++		else
++			list_add_tail(&p->l_node, rdd->middle);
++	}
++
++	return rdd->err;
++}
++
++static void ovl_cache_free(struct list_head *list)
++{
++	struct ovl_cache_entry *p;
++	struct ovl_cache_entry *n;
++
++	list_for_each_entry_safe(p, n, list, l_node)
++		kfree(p);
++
++	INIT_LIST_HEAD(list);
++}
++
++static int ovl_fill_upper(void *buf, const char *name, int namelen,
++			  loff_t offset, u64 ino, unsigned int d_type)
++{
++	struct ovl_readdir_data *rdd = buf;
++
++	rdd->count++;
++	return ovl_cache_entry_add_rb(rdd, name, namelen, ino, d_type);
++}
++
++static inline int ovl_dir_read(struct path *realpath,
++			       struct ovl_readdir_data *rdd, filldir_t filler)
++{
++	struct file *realfile;
++	int err;
++
++	realfile = vfs_open(realpath, O_RDONLY | O_DIRECTORY, current_cred());
++	if (IS_ERR(realfile))
++		return PTR_ERR(realfile);
++
++	do {
++		rdd->count = 0;
++		rdd->err = 0;
++		err = vfs_readdir(realfile, filler, rdd);
++		if (err >= 0)
++			err = rdd->err;
++	} while (!err && rdd->count);
++	fput(realfile);
++
++	return 0;
++}
++
++static void ovl_dir_reset(struct file *file)
++{
++	struct ovl_dir_file *od = file->private_data;
++	enum ovl_path_type type = ovl_path_type(file->f_path.dentry);
++
++	if (ovl_dentry_version_get(file->f_path.dentry) != od->cache_version) {
++		list_del_init(&od->cursor);
++		ovl_cache_free(&od->cache);
++		od->is_cached = false;
++	}
++	WARN_ON(!od->is_real && type != OVL_PATH_MERGE);
++	if (od->is_real && type == OVL_PATH_MERGE) {
++		fput(od->realfile);
++		od->realfile = NULL;
++		od->is_real = false;
++	}
++}
++
++static int ovl_dir_mark_whiteouts(struct ovl_readdir_data *rdd)
++{
++	struct ovl_cache_entry *p;
++	struct dentry *dentry;
++	const struct cred *old_cred;
++	struct cred *override_cred;
++
++	override_cred = prepare_creds();
++	if (!override_cred) {
++		ovl_cache_free(rdd->list);
++		return -ENOMEM;
++	}
++
++	/*
++	 * CAP_SYS_ADMIN for getxattr
++	 * CAP_DAC_OVERRIDE for lookup
++	 */
++	cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
++	cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
++	old_cred = override_creds(override_cred);
++
++	mutex_lock(&rdd->dir->d_inode->i_mutex);
++	list_for_each_entry(p, rdd->list, l_node) {
++		if (p->type != DT_LNK)
++			continue;
++
++		dentry = lookup_one_len(p->name, rdd->dir, p->len);
++		if (IS_ERR(dentry))
++			continue;
++
++		p->is_whiteout = ovl_is_whiteout(dentry);
++		dput(dentry);
++	}
++	mutex_unlock(&rdd->dir->d_inode->i_mutex);
++
++	revert_creds(old_cred);
++	put_cred(override_cred);
++
++	return 0;
++}
++
++static inline int ovl_dir_read_merged(struct path *upperpath, struct path *lowerpath,
++			       struct ovl_readdir_data *rdd)
++{
++	int err;
++	struct rb_root root = RB_ROOT;
++	struct list_head middle;
++
++	rdd->root = &root;
++	if (upperpath->dentry) {
++		rdd->dir = upperpath->dentry;
++		err = ovl_dir_read(upperpath, rdd, ovl_fill_upper);
++		if (err)
++			goto out;
++
++		err = ovl_dir_mark_whiteouts(rdd);
++		if (err)
++			goto out;
++	}
++	/*
++	 * Insert lowerpath entries before upperpath ones, this allows
++	 * offsets to be reasonably constant
++	 */
++	list_add(&middle, rdd->list);
++	rdd->middle = &middle;
++	err = ovl_dir_read(lowerpath, rdd, ovl_fill_lower);
++	list_del(&middle);
++out:
++	rdd->root = NULL;
++
++	return err;
++}
++
++static void ovl_seek_cursor(struct ovl_dir_file *od, loff_t pos)
++{
++	struct list_head *l;
++	loff_t off;
++
++	l = od->cache.next;
++	for (off = 0; off < pos; off++) {
++		if (l == &od->cache)
++			break;
++		l = l->next;
++	}
++	list_move_tail(&od->cursor, l);
++}
++
++static int ovl_readdir(struct file *file, void *buf, filldir_t filler)
++{
++	struct ovl_dir_file *od = file->private_data;
++	int res;
++
++	if (!file->f_pos)
++		ovl_dir_reset(file);
++
++	if (od->is_real) {
++		res = vfs_readdir(od->realfile, filler, buf);
++		file->f_pos = od->realfile->f_pos;
++
++		return res;
++	}
++
++	if (!od->is_cached) {
++		struct path lowerpath;
++		struct path upperpath;
++		struct ovl_readdir_data rdd = { .list = &od->cache };
++
++		ovl_path_lower(file->f_path.dentry, &lowerpath);
++		ovl_path_upper(file->f_path.dentry, &upperpath);
++
++		res = ovl_dir_read_merged(&upperpath, &lowerpath, &rdd);
++		if (res) {
++			ovl_cache_free(rdd.list);
++			return res;
++		}
++
++		od->cache_version = ovl_dentry_version_get(file->f_path.dentry);
++		od->is_cached = true;
++
++		ovl_seek_cursor(od, file->f_pos);
++	}
++
++	while (od->cursor.next != &od->cache) {
++		int over;
++		loff_t off;
++		struct ovl_cache_entry *p;
++
++		p = list_entry(od->cursor.next, struct ovl_cache_entry, l_node);
++		off = file->f_pos;
++		if (!p->is_whiteout) {
++			over = filler(buf, p->name, p->len, off, p->ino, p->type);
++			if (over)
++				break;
++		}
++		file->f_pos++;
++		list_move(&od->cursor, &p->l_node);
++	}
++
++	return 0;
++}
++
++static loff_t ovl_dir_llseek(struct file *file, loff_t offset, int origin)
++{
++	loff_t res;
++	struct ovl_dir_file *od = file->private_data;
++
++	mutex_lock(&file->f_dentry->d_inode->i_mutex);
++	if (!file->f_pos)
++		ovl_dir_reset(file);
++
++	if (od->is_real) {
++		res = vfs_llseek(od->realfile, offset, origin);
++		file->f_pos = od->realfile->f_pos;
++	} else {
++		res = -EINVAL;
++
++		switch (origin) {
++		case SEEK_CUR:
++			offset += file->f_pos;
++			break;
++		case SEEK_SET:
++			break;
++		default:
++			goto out_unlock;
++		}
++		if (offset < 0)
++			goto out_unlock;
++
++		if (offset != file->f_pos) {
++			file->f_pos = offset;
++			if (od->is_cached)
++				ovl_seek_cursor(od, offset);
++		}
++		res = offset;
++	}
++out_unlock:
++	mutex_unlock(&file->f_dentry->d_inode->i_mutex);
++
++	return res;
++}
++
++static int ovl_dir_fsync(struct file *file, int datasync)
++{
++	struct ovl_dir_file *od = file->private_data;
++
++	/* May need to reopen directory if it got copied up */
++	if (!od->realfile) {
++		struct path upperpath;
++
++		ovl_path_upper(file->f_path.dentry, &upperpath);
++		od->realfile = vfs_open(&upperpath, O_RDONLY, current_cred());
++		if (IS_ERR(od->realfile))
++			return PTR_ERR(od->realfile);
++	}
++
++	return vfs_fsync(od->realfile, datasync);
++}
++
++static int ovl_dir_release(struct inode *inode, struct file *file)
++{
++	struct ovl_dir_file *od = file->private_data;
++
++	list_del(&od->cursor);
++	ovl_cache_free(&od->cache);
++	if (od->realfile)
++		fput(od->realfile);
++	kfree(od);
++
++	return 0;
++}
++
++static int ovl_dir_open(struct inode *inode, struct file *file)
++{
++	struct path realpath;
++	struct file *realfile;
++	struct ovl_dir_file *od;
++	enum ovl_path_type type;
++
++	od = kzalloc(sizeof(struct ovl_dir_file), GFP_KERNEL);
++	if (!od)
++		return -ENOMEM;
++
++	type = ovl_path_real(file->f_path.dentry, &realpath);
++	realfile = vfs_open(&realpath, file->f_flags, current_cred());
++	if (IS_ERR(realfile)) {
++		kfree(od);
++		return PTR_ERR(realfile);
++	}
++	INIT_LIST_HEAD(&od->cache);
++	INIT_LIST_HEAD(&od->cursor);
++	od->is_cached = false;
++	od->realfile = realfile;
++	od->is_real = (type != OVL_PATH_MERGE);
++	file->private_data = od;
++
++	return 0;
++}
++
++const struct file_operations ovl_dir_operations = {
++	.read		= generic_read_dir,
++	.open		= ovl_dir_open,
++	.readdir	= ovl_readdir,
++	.llseek		= ovl_dir_llseek,
++	.fsync		= ovl_dir_fsync,
++	.release	= ovl_dir_release,
++};
++
++static int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list)
++{
++	int err;
++	struct path lowerpath;
++	struct path upperpath;
++	struct ovl_cache_entry *p;
++	struct ovl_readdir_data rdd = { .list = list };
++
++	ovl_path_upper(dentry, &upperpath);
++	ovl_path_lower(dentry, &lowerpath);
++
++	err = ovl_dir_read_merged(&upperpath, &lowerpath, &rdd);
++	if (err)
++		return err;
++
++	err = 0;
++
++	list_for_each_entry(p, list, l_node) {
++		if (p->is_whiteout)
++			continue;
++
++		if (p->name[0] == '.') {
++			if (p->len == 1)
++				continue;
++			if (p->len == 2 && p->name[1] == '.')
++				continue;
++		}
++		err = -ENOTEMPTY;
++		break;
++	}
++
++	return err;
++}
++
++static int ovl_remove_whiteouts(struct dentry *dir, struct list_head *list)
++{
++	struct path upperpath;
++	struct dentry *upperdir;
++	struct ovl_cache_entry *p;
++	const struct cred *old_cred;
++	struct cred *override_cred;
++	int err;
++
++	ovl_path_upper(dir, &upperpath);
++	upperdir = upperpath.dentry;
++
++	override_cred = prepare_creds();
++	if (!override_cred)
++		return -ENOMEM;
++
++	/*
++	 * CAP_DAC_OVERRIDE for lookup and unlink
++	 * CAP_SYS_ADMIN for setxattr of "trusted" namespace
++	 * CAP_FOWNER for unlink in sticky directory
++	 */
++	cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
++	cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
++	cap_raise(override_cred->cap_effective, CAP_FOWNER);
++	old_cred = override_creds(override_cred);
++
++	err = vfs_setxattr(upperdir, ovl_opaque_xattr, "y", 1, 0);
++	if (err)
++		goto out_revert_creds;
++
++	mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT);
++	list_for_each_entry(p, list, l_node) {
++		struct dentry *dentry;
++		int ret;
++
++		if (!p->is_whiteout)
++			continue;
++
++		dentry = lookup_one_len(p->name, upperdir, p->len);
++		if (IS_ERR(dentry)) {
++			printk(KERN_WARNING "overlayfs: failed to lookup whiteout %.*s: %li\n", p->len, p->name, PTR_ERR(dentry));
++			continue;
++		}
++		ret = vfs_unlink(upperdir->d_inode, dentry);
++		dput(dentry);
++		if (ret)
++			printk(KERN_WARNING "overlayfs: failed to unlink whiteout %.*s: %i\n", p->len, p->name, ret);
++	}
++	mutex_unlock(&upperdir->d_inode->i_mutex);
++
++out_revert_creds:
++	revert_creds(old_cred);
++	put_cred(override_cred);
++
++	return err;
++}
++
++int ovl_check_empty_and_clear(struct dentry *dentry, enum ovl_path_type type)
++{
++	int err;
++	LIST_HEAD(list);
++
++	err = ovl_check_empty_dir(dentry, &list);
++	if (!err && type == OVL_PATH_MERGE)
++		err = ovl_remove_whiteouts(dentry, &list);
++
++	ovl_cache_free(&list);
++
++	return err;
++}
+--- /dev/null
++++ b/fs/overlayfs/super.c
+@@ -0,0 +1,656 @@
++/*
++ *
++ * Copyright (C) 2011 Novell Inc.
++ *
++ * This program is free software; you can redistribute it and/or modify it
++ * under the terms of the GNU General Public License version 2 as published by
++ * the Free Software Foundation.
++ */
++
++#include <linux/fs.h>
++#include <linux/namei.h>
++#include <linux/xattr.h>
++#include <linux/security.h>
++#include <linux/mount.h>
++#include <linux/slab.h>
++#include <linux/parser.h>
++#include <linux/module.h>
++#include <linux/seq_file.h>
++#include "overlayfs.h"
++
++MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
++MODULE_DESCRIPTION("Overlay filesystem");
++MODULE_LICENSE("GPL");
++
++struct ovl_config {
++	char *lowerdir;
++	char *upperdir;
++};
++
++/* private information held for overlayfs's superblock */
++struct ovl_fs {
++	struct vfsmount *upper_mnt;
++	struct vfsmount *lower_mnt;
++	/* pathnames of lower and upper dirs, for show_options */
++	struct ovl_config config;
++};
++
++/* private information held for every overlayfs dentry */
++struct ovl_entry {
++	/*
++	 * Keep "double reference" on upper dentries, so that
++	 * d_delete() doesn't think it's OK to reset d_inode to NULL.
++	 */
++	struct dentry *__upperdentry;
++	struct dentry *lowerdentry;
++	union {
++		struct {
++			u64 version;
++			bool opaque;
++		};
++		struct rcu_head rcu;
++	};
++};
++
++const char *ovl_whiteout_xattr = "trusted.overlay.whiteout";
++const char *ovl_opaque_xattr = "trusted.overlay.opaque";
++
++
++enum ovl_path_type ovl_path_type(struct dentry *dentry)
++{
++	struct ovl_entry *oe = dentry->d_fsdata;
++
++	if (oe->__upperdentry) {
++		if (oe->lowerdentry && S_ISDIR(dentry->d_inode->i_mode))
++			return OVL_PATH_MERGE;
++		else
++			return OVL_PATH_UPPER;
++	} else {
++		return OVL_PATH_LOWER;
++	}
++}
++
++static struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe)
++{
++	struct dentry *upperdentry = ACCESS_ONCE(oe->__upperdentry);
++	smp_read_barrier_depends();
++	return upperdentry;
++}
++
++void ovl_path_upper(struct dentry *dentry, struct path *path)
++{
++	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
++	struct ovl_entry *oe = dentry->d_fsdata;
++
++	path->mnt = ofs->upper_mnt;
++	path->dentry = ovl_upperdentry_dereference(oe);
++}
++
++void ovl_path_lower(struct dentry *dentry, struct path *path)
++{
++	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
++	struct ovl_entry *oe = dentry->d_fsdata;
++
++	path->mnt = ofs->lower_mnt;
++	path->dentry = oe->lowerdentry;
++}
++
++enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
++{
++
++	enum ovl_path_type type = ovl_path_type(dentry);
++
++	if (type == OVL_PATH_LOWER)
++		ovl_path_lower(dentry, path);
++	else
++		ovl_path_upper(dentry, path);
++
++	return type;
++}
++
++struct dentry *ovl_dentry_upper(struct dentry *dentry)
++{
++	struct ovl_entry *oe = dentry->d_fsdata;
++
++	return ovl_upperdentry_dereference(oe);
++}
++
++struct dentry *ovl_dentry_lower(struct dentry *dentry)
++{
++	struct ovl_entry *oe = dentry->d_fsdata;
++
++	return oe->lowerdentry;
++}
++
++struct dentry *ovl_dentry_real(struct dentry *dentry)
++{
++	struct ovl_entry *oe = dentry->d_fsdata;
++	struct dentry *realdentry;
++
++	realdentry = ovl_upperdentry_dereference(oe);
++	if (!realdentry)
++		realdentry = oe->lowerdentry;
++
++	return realdentry;
++}
++
++struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper)
++{
++	struct dentry *realdentry;
++
++	realdentry = ovl_upperdentry_dereference(oe);
++	if (realdentry) {
++		*is_upper = true;
++	} else {
++		realdentry = oe->lowerdentry;
++		*is_upper = false;
++	}
++	return realdentry;
++}
++
++bool ovl_dentry_is_opaque(struct dentry *dentry)
++{
++	struct ovl_entry *oe = dentry->d_fsdata;
++	return oe->opaque;
++}
++
++void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque)
++{
++	struct ovl_entry *oe = dentry->d_fsdata;
++	oe->opaque = opaque;
++}
++
++void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry)
++{
++	struct ovl_entry *oe = dentry->d_fsdata;
++
++	WARN_ON(!mutex_is_locked(&upperdentry->d_parent->d_inode->i_mutex));
++	WARN_ON(oe->__upperdentry);
++	BUG_ON(!upperdentry->d_inode);
++	smp_wmb();
++	oe->__upperdentry = dget(upperdentry);
++}
++
++void ovl_dentry_version_inc(struct dentry *dentry)
++{
++	struct ovl_entry *oe = dentry->d_fsdata;
++
++	WARN_ON(!mutex_is_locked(&dentry->d_inode->i_mutex));
++	oe->version++;
++}
++
++u64 ovl_dentry_version_get(struct dentry *dentry)
++{
++	struct ovl_entry *oe = dentry->d_fsdata;
++
++	WARN_ON(!mutex_is_locked(&dentry->d_inode->i_mutex));
++	return oe->version;
++}
++
++bool ovl_is_whiteout(struct dentry *dentry)
++{
++	int res;
++	char val;
++
++	if (!dentry)
++		return false;
++	if (!dentry->d_inode)
++		return false;
++	if (!S_ISLNK(dentry->d_inode->i_mode))
++		return false;
++
++	res = vfs_getxattr(dentry, ovl_whiteout_xattr, &val, 1);
++	if (res == 1 && val == 'y')
++		return true;
++
++	return false;
++}
++
++static bool ovl_is_opaquedir(struct dentry *dentry)
++{
++	int res;
++	char val;
++
++	if (!S_ISDIR(dentry->d_inode->i_mode))
++		return false;
++
++	res = vfs_getxattr(dentry, ovl_opaque_xattr, &val, 1);
++	if (res == 1 && val == 'y')
++		return true;
++
++	return false;
++}
++
++static void ovl_entry_free(struct rcu_head *head)
++{
++	struct ovl_entry *oe = container_of(head, struct ovl_entry, rcu);
++	kfree(oe);
++}
++
++static void ovl_dentry_release(struct dentry *dentry)
++{
++	struct ovl_entry *oe = dentry->d_fsdata;
++
++	if (oe) {
++		dput(oe->__upperdentry);
++		dput(oe->__upperdentry);
++		dput(oe->lowerdentry);
++		call_rcu(&oe->rcu, ovl_entry_free);
++	}
++}
++
++const struct dentry_operations ovl_dentry_operations = {
++	.d_release = ovl_dentry_release,
++};
++
++static struct ovl_entry *ovl_alloc_entry(void)
++{
++	return kzalloc(sizeof(struct ovl_entry), GFP_KERNEL);
++}
++
++static inline struct dentry *ovl_lookup_real(struct dentry *dir, struct qstr *name)
++{
++	struct dentry *dentry;
++
++	mutex_lock(&dir->d_inode->i_mutex);
++	dentry = lookup_one_len(name->name, dir, name->len);
++	mutex_unlock(&dir->d_inode->i_mutex);
++
++	if (IS_ERR(dentry)) {
++		if (PTR_ERR(dentry) == -ENOENT)
++			dentry = NULL;
++	} else if (!dentry->d_inode) {
++		dput(dentry);
++		dentry = NULL;
++	}
++	return dentry;
++}
++
++static int ovl_do_lookup(struct dentry *dentry)
++{
++	struct ovl_entry *oe;
++	struct dentry *upperdir;
++	struct dentry *lowerdir;
++	struct dentry *upperdentry = NULL;
++	struct dentry *lowerdentry = NULL;
++	struct inode *inode = NULL;
++	int err;
++
++	err = -ENOMEM;
++	oe = ovl_alloc_entry();
++	if (!oe)
++		goto out;
++
++	upperdir = ovl_dentry_upper(dentry->d_parent);
++	lowerdir = ovl_dentry_lower(dentry->d_parent);
++
++	if (upperdir) {
++		upperdentry = ovl_lookup_real(upperdir, &dentry->d_name);
++		err = PTR_ERR(upperdentry);
++		if (IS_ERR(upperdentry))
++			goto out_put_dir;
++
++		if (lowerdir && upperdentry &&
++		    (S_ISLNK(upperdentry->d_inode->i_mode) ||
++		     S_ISDIR(upperdentry->d_inode->i_mode))) {
++			const struct cred *old_cred;
++			struct cred *override_cred;
++
++			err = -ENOMEM;
++			override_cred = prepare_creds();
++			if (!override_cred)
++				goto out_dput_upper;
++
++			/* CAP_SYS_ADMIN needed for getxattr */
++			cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
++			old_cred = override_creds(override_cred);
++
++			if (ovl_is_opaquedir(upperdentry)) {
++				oe->opaque = true;
++			} else if (ovl_is_whiteout(upperdentry)) {
++				dput(upperdentry);
++				upperdentry = NULL;
++				oe->opaque = true;
++			}
++			revert_creds(old_cred);
++			put_cred(override_cred);
++		}
++	}
++	if (lowerdir && !oe->opaque) {
++		lowerdentry = ovl_lookup_real(lowerdir, &dentry->d_name);
++		err = PTR_ERR(lowerdentry);
++		if (IS_ERR(lowerdentry))
++			goto out_dput_upper;
++	}
++
++	if (lowerdentry && upperdentry &&
++	    (!S_ISDIR(upperdentry->d_inode->i_mode) ||
++	     !S_ISDIR(lowerdentry->d_inode->i_mode))) {
++		dput(lowerdentry);
++		lowerdentry = NULL;
++		oe->opaque = true;
++	}
++
++	if (lowerdentry || upperdentry) {
++		struct dentry *realdentry;
++
++		realdentry = upperdentry ? upperdentry : lowerdentry;
++		err = -ENOMEM;
++		inode = ovl_new_inode(dentry->d_sb, realdentry->d_inode->i_mode, oe);
++		if (!inode)
++			goto out_dput;
++	}
++
++	if (upperdentry)
++		oe->__upperdentry = dget(upperdentry);
++
++	if (lowerdentry)
++		oe->lowerdentry = lowerdentry;
++
++	dentry->d_fsdata = oe;
++	dentry->d_op = &ovl_dentry_operations;
++	d_add(dentry, inode);
++
++	return 0;
++
++out_dput:
++	dput(lowerdentry);
++out_dput_upper:
++	dput(upperdentry);
++out_put_dir:
++	kfree(oe);
++out:
++	return err;
++}
++
++struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
++			  struct nameidata *nd)
++{
++	int err = ovl_do_lookup(dentry);
++
++	if (err)
++		return ERR_PTR(err);
++
++	return NULL;
++}
 +
 +static void ovl_put_super(struct super_block *sb)
 +{
@@ -2400,6 +2839,8 @@
 +	mntput(ufs->upper_mnt);
 +	mntput(ufs->lower_mnt);
 +
++	kfree(ufs->config.lowerdir);
++	kfree(ufs->config.upperdir);
 +	kfree(ufs);
 +}
 +
@@ -2441,15 +2882,27 @@
 +	return path.dentry->d_sb->s_op->statfs(path.dentry, buf);
 +}
 +
++/**
++ * ovl_show_options
++ *
++ * Prints the mount options for a given superblock.
++ * Returns zero; does not fail.
++ */
++static int ovl_show_options(struct seq_file *m, struct vfsmount *mnt)
++{
++	struct super_block *sb = mnt->mnt_sb;
++	struct ovl_fs *ufs = sb->s_fs_info;
++
++	seq_printf(m, ",lowerdir=%s", ufs->config.lowerdir);
++	seq_printf(m, ",upperdir=%s", ufs->config.upperdir);
++	return 0;
++}
++
 +static const struct super_operations ovl_super_operations = {
 +	.put_super	= ovl_put_super,
 +	.remount_fs	= ovl_remount_fs,
 +	.statfs		= ovl_statfs,
-+};
-+
-+struct ovl_config {
-+	char *lowerdir;
-+	char *upperdir;
++	.show_options	= ovl_show_options,
 +};
 +
 +enum {
@@ -2509,37 +2962,36 @@
 +	struct dentry *root_dentry;
 +	struct ovl_entry *oe;
 +	struct ovl_fs *ufs;
-+	struct ovl_config config;
 +	int err;
 +
-+	err = ovl_parse_opt((char *) data, &config);
-+	if (err)
++	err = -ENOMEM;
++	ufs = kmalloc(sizeof(struct ovl_fs), GFP_KERNEL);
++	if (!ufs)
 +		goto out;
 +
++	err = ovl_parse_opt((char *) data, &ufs->config);
++	if (err)
++		goto out_free_ufs;
++
 +	err = -EINVAL;
-+	if (!config.upperdir || !config.lowerdir) {
++	if (!ufs->config.upperdir || !ufs->config.lowerdir) {
 +		printk(KERN_ERR "overlayfs: missing upperdir or lowerdir\n");
 +		goto out_free_config;
 +	}
 +
-+	err = -ENOMEM;
-+	ufs = kmalloc(sizeof(struct ovl_fs), GFP_KERNEL);
-+	if (!ufs)
-+		goto out_free_config;
-+
 +	oe = ovl_alloc_entry();
 +	if (oe == NULL)
-+		goto out_free_ufs;
++		goto out_free_config;
 +
 +	root_inode = ovl_new_inode(sb, S_IFDIR, oe);
 +	if (!root_inode)
 +		goto out_free_oe;
 +
-+	err = kern_path(config.upperdir, LOOKUP_FOLLOW, &upperpath);
++	err = kern_path(ufs->config.upperdir, LOOKUP_FOLLOW, &upperpath);
 +	if (err)
 +		goto out_put_root;
 +
-+	err = kern_path(config.lowerdir, LOOKUP_FOLLOW, &lowerpath);
++	err = kern_path(ufs->config.lowerdir, LOOKUP_FOLLOW, &lowerpath);
 +	if (err)
 +		goto out_put_upperpath;
 +
@@ -2548,6 +3000,16 @@
 +	    !S_ISDIR(lowerpath.dentry->d_inode->i_mode))
 +		goto out_put_lowerpath;
 +
++	sb->s_stack_depth = max(upperpath.mnt->mnt_sb->s_stack_depth,
++				lowerpath.mnt->mnt_sb->s_stack_depth) + 1;
++
++	err = -EINVAL;
++	if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
++		printk(KERN_ERR "overlayfs: maximum fs stacking depth exceeded\n");
++		goto out_put_lowerpath;
++	}
++
++
 +	ufs->upper_mnt = clone_private_mount(&upperpath);
 +	err = PTR_ERR(ufs->upper_mnt);
 +	if (IS_ERR(ufs->upper_mnt)) {
@@ -2562,6 +3024,16 @@
 +		goto out_put_upper_mnt;
 +	}
 +
++	/*
++	 * Make lower_mnt R/O.  That way fchmod/fchown on lower file
++	 * will fail instead of modifying lower fs.
++	 */
++	ufs->lower_mnt->mnt_flags |= MNT_READONLY;
++
++	/* If the upper fs is r/o, we mark overlayfs r/o too */
++	if (ufs->upper_mnt->mnt_sb->s_flags & MS_RDONLY)
++		sb->s_flags |= MS_RDONLY;
++
 +	if (!(sb->s_flags & MS_RDONLY)) {
 +		err = mnt_want_write(ufs->upper_mnt);
 +		if (err)
@@ -2576,7 +3048,7 @@
 +	mntput(upperpath.mnt);
 +	mntput(lowerpath.mnt);
 +
-+	oe->__upperdentry = upperpath.dentry;
++	oe->__upperdentry = dget(upperpath.dentry);
 +	oe->lowerdentry = lowerpath.dentry;
 +
 +	root_dentry->d_fsdata = oe;
@@ -2603,11 +3075,11 @@
 +	iput(root_inode);
 +out_free_oe:
 +	kfree(oe);
++out_free_config:
++	kfree(ufs->config.lowerdir);
++	kfree(ufs->config.upperdir);
 +out_free_ufs:
 +	kfree(ufs);
-+out_free_config:
-+	kfree(config.lowerdir);
-+	kfree(config.upperdir);
 +out:
 +	return err;
 +}
@@ -2637,204 +3109,68 @@
 +
 +module_init(ovl_init);
 +module_exit(ovl_exit);
---- a/fs/Kconfig
-+++ b/fs/Kconfig
-@@ -63,6 +63,7 @@ source "fs/quota/Kconfig"
+--- a/fs/splice.c
++++ b/fs/splice.c
+@@ -1296,6 +1296,7 @@ long do_splice_direct(struct file *in, l
  
- source "fs/autofs4/Kconfig"
- source "fs/fuse/Kconfig"
-+source "fs/overlayfs/Kconfig"
+ 	return ret;
+ }
++EXPORT_SYMBOL(do_splice_direct);
  
- config CUSE
- 	tristate "Character device in Userspace support"
---- a/fs/Makefile
-+++ b/fs/Makefile
-@@ -105,6 +105,7 @@ obj-$(CONFIG_QNX4FS_FS)		+= qnx4/
- obj-$(CONFIG_AUTOFS4_FS)	+= autofs4/
- obj-$(CONFIG_ADFS_FS)		+= adfs/
- obj-$(CONFIG_FUSE_FS)		+= fuse/
-+obj-$(CONFIG_OVERLAYFS_FS)	+= overlayfs/
- obj-$(CONFIG_UDF_FS)		+= udf/
- obj-$(CONFIG_SUN_OPENPROMFS)	+= openpromfs/
- obj-$(CONFIG_OMFS_FS)		+= omfs/
---- /dev/null
-+++ b/fs/overlayfs/Kconfig
-@@ -0,0 +1,4 @@
-+config OVERLAYFS_FS
-+	tristate "Overlay filesystem support"
-+	help
-+	  Add support for overlay filesystem.
---- /dev/null
-+++ b/fs/overlayfs/Makefile
-@@ -0,0 +1,5 @@
-+#
-+# Makefile for the overlay filesystem.
-+#
-+
-+obj-$(CONFIG_OVERLAYFS_FS) += overlayfs.o
---- /dev/null
-+++ b/Documentation/filesystems/overlayfs.txt
-@@ -0,0 +1,163 @@
-+Written by: Neil Brown <neilb@suse.de>
-+
-+Overlay Filesystem
-+==================
-+
-+This document describes a prototype for a new approach to providing
-+overlay-filesystem functionality in Linux (sometimes referred to as
-+union-filesystems).  An overlay-filesystem tries to present a
-+filesystem which is the result over overlaying one filesystem on top
-+of the other.
-+
-+The result will inevitably fail to look exactly like a normal
-+filesystem for various technical reasons.  The expectation is that
-+many use cases will be able to ignore these differences.
-+
-+This approach is 'hybrid' because the objects that appear in the
-+filesystem do not all appear to belong to that filesystem.  In many
-+cases an object accessed in the union will be indistinguishable
-+from accessing the corresponding object from the original filesystem.
-+This is most obvious from the 'st_dev' field returned by stat(2).
-+
-+While directories will report an st_dev from the overlay-filesystem,
-+all non-directory objects will report an st_dev from the lower or
-+upper filesystem that is providing the object.  Similarly st_ino will
-+only be unique when combined with st_dev, and both of these can change
-+over the lifetime of a non-directory object.  Many applications and
-+tools ignore these values and will not be affected.
-+
-+Upper and Lower
-+---------------
-+
-+An overlay filesystem combines two filesystems - an 'upper' filesystem
-+and a 'lower' filesystem.  When a name exists in both filesystems, the
-+object in the 'upper' filesystem is visible while the object in the
-+'lower' filesystem is either hidden or, in the case of directories,
-+merged with the 'upper' object.
-+
-+It would be more correct to refer to an upper and lower 'directory
-+tree' rather than 'filesystem' as it is quite possible for both
-+directory trees to be in the same filesystem and there is no
-+requirement that the root of a filesystem be given for either upper or
-+lower.
-+
-+The lower filesystem can be any filesystem supported by Linux and does
-+not need to be writable.  The lower filesystem can even be another
-+overlayfs.  The upper filesystem will normally be writable and if it
-+is it must support the creation of trusted.* extended attributes, and
-+must provide valid d_type in readdir responses, at least for symbolic
-+links - so NFS is not suitable.
-+
-+A read-only overlay of two read-only filesystems may use any
-+filesystem type.
-+
-+Directories
-+-----------
-+
-+Overlaying mainly involved directories.  If a given name appears in both
-+upper and lower filesystems and refers to a non-directory in either,
-+then the lower object is hidden - the name refers only to the upper
-+object.
-+
-+Where both upper and lower objects are directories, a merged directory
-+is formed.
-+
-+At mount time, the two directories given as mount options are combined
-+into a merged directory.  Then whenever a lookup is requested in such
-+a merged directory, the lookup is performed in each actual directory
-+and the combined result is cached in the dentry belonging to the overlay
-+filesystem.  If both actual lookups find directories, both are stored
-+and a merged directory is created, otherwise only one is stored: the
-+upper if it exists, else the lower.
-+
-+Only the lists of names from directories are merged.  Other content
-+such as metadata and extended attributes are reported for the upper
-+directory only.  These attributes of the lower directory are hidden.
-+
-+whiteouts and opaque directories
-+--------------------------------
-+
-+In order to support rm and rmdir without changing the lower
-+filesystem, an overlay filesystem needs to record in the upper filesystem
-+that files have been removed.  This is done using whiteouts and opaque
-+directories (non-directories are always opaque).
-+
-+The overlay filesystem uses extended attributes with a
-+"trusted.overlay."  prefix to record these details.
-+
-+A whiteout is created as a symbolic link with target
-+"(overlay-whiteout)" and with xattr "trusted.overlay.whiteout" set to "y".
-+When a whiteout is found in the upper level of a merged directory, any
-+matching name in the lower level is ignored, and the whiteout itself
-+is also hidden.
-+
-+A directory is made opaque by setting the xattr "trusted.overlay.opaque"
-+to "y".  Where the upper filesystem contains an opaque directory, any
-+directory in the lower filesystem with the same name is ignored.
-+
-+readdir
-+-------
-+
-+When a 'readdir' request is made on a merged directory, the upper and
-+lower directories are each read and the name lists merged in the
-+obvious way (upper is read first, then lower - entries that already
-+exist are not re-added).  This merged name list is cached in the
-+'struct file' and so remains as long as the file is kept open.  If the
-+directory is opened and read by two processes at the same time, they
-+will each have separate caches.  A seekdir to the start of the
-+directory (offset 0) followed by a readdir will cause the cache to be
-+discarded and rebuilt.
-+
-+This means that changes to the merged directory do not appear while a
-+directory is being read.  This is unlikely to be noticed by many
-+programs.
-+
-+seek offsets are assigned sequentially when the directories are read.
-+Thus if
-+  - read part of a directory
-+  - remember an offset, and close the directory
-+  - re-open the directory some time later
-+  - seek to the remembered offset
-+
-+there may be little correlation between the old and new locations in
-+the list of filenames, particularly if anything has changed in the
-+directory.
-+
-+Readdir on directories that are not merged is simply handled by the
-+underlying directory (upper or lower).
-+
-+
-+Non-directories
-+---------------
-+
-+Objects that are not directories (files, symlinks, device-special
-+files etc.) are presented either from the upper or lower filesystem as
-+appropriate.  When a file in the lower filesystem is accessed in a way
-+the requires write-access, such as opening for write access, changing
-+some metadata etc., the file is first copied from the lower filesystem
-+to the upper filesystem (copy_up).  Note that creating a hard-link
-+also requires copy_up, though of course creation of a symlink does
-+not.
-+
-+The copy_up process first makes sure that the containing directory
-+exists in the upper filesystem - creating it and any parents as
-+necessary.  It then creates the object with the same metadata (owner,
-+mode, mtime, symlink-target etc.) and then if the object is a file, the
-+data is copied from the lower to the upper filesystem.  Finally any
-+extended attributes are copied up.
-+
-+Once the copy_up is complete, the overlay filesystem simply
-+provides direct access to the newly created file in the upper
-+filesystem - future operations on the file are barely noticed by the
-+overlay filesystem (though an operation on the name of the file such as
-+rename or unlink will of course be noticed and handled).
+ static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
+ 			       struct pipe_inode_info *opipe,
+--- a/include/linux/fs.h
++++ b/include/linux/fs.h
+@@ -476,6 +476,12 @@ struct iattr {
+  */
+ #include <linux/quota.h>
+ 
++/*
++ * Maximum number of layers of fs stack.  Needs to be limited to
++ * prevent kernel stack overflow
++ */
++#define FILESYSTEM_MAX_STACK_DEPTH 2
 +
-+Changes to underlying filesystems
-+---------------------------------
+ /** 
+  * enum positive_aop_returns - aop return codes with specific semantics
+  *
+@@ -1429,6 +1435,11 @@ struct super_block {
+ 	 */
+ 	char __rcu *s_options;
+ 	const struct dentry_operations *s_d_op; /* default d_op for dentries */
 +
-+Offline changes, when the overlay is not mounted, are allowed to either
-+the upper or the lower trees.
++	/*
++	 * Indicates how deep in a filesystem stack this SB is
++	 */
++	int s_stack_depth;
+ };
+ 
+ extern struct timespec current_fs_time(struct super_block *sb);
+@@ -1594,6 +1605,7 @@ struct inode_operations {
+ 	void (*truncate_range)(struct inode *, loff_t, loff_t);
+ 	int (*fiemap)(struct inode *, struct fiemap_extent_info *, u64 start,
+ 		      u64 len);
++	struct file *(*open)(struct dentry *, int flags, const struct cred *);
+ } ____cacheline_aligned;
+ 
+ struct seq_file;
+@@ -1988,6 +2000,7 @@ extern long do_sys_open(int dfd, const c
+ extern struct file *filp_open(const char *, int, int);
+ extern struct file *file_open_root(struct dentry *, struct vfsmount *,
+ 				   const char *, int);
++extern struct file *vfs_open(struct path *, int flags, const struct cred *);
+ extern struct file * dentry_open(struct dentry *, struct vfsmount *, int,
+ 				 const struct cred *);
+ extern int filp_close(struct file *, fl_owner_t id);
+--- a/include/linux/mount.h
++++ b/include/linux/mount.h
+@@ -100,6 +100,9 @@ extern void mnt_pin(struct vfsmount *mnt
+ extern void mnt_unpin(struct vfsmount *mnt);
+ extern int __mnt_is_readonly(struct vfsmount *mnt);
+ 
++struct path;
++extern struct vfsmount *clone_private_mount(struct path *path);
 +
-+Changes to the underlying filesystems while part of a mounted overlay
-+filesystem are not allowed.  This is not yet enforced, but will be in
-+the future.
+ extern struct vfsmount *do_kern_mount(const char *fstype, int flags,
+ 				      const char *name, void *data);
+ 
diff --git a/target/linux/generic/patches-3.0/100-overlayfs_v10.patch b/target/linux/generic/patches-3.0/100-overlayfs_v11.patch
index 179626324c..1dccf7b1ce 100644
--- a/target/linux/generic/patches-3.0/100-overlayfs_v10.patch
+++ b/target/linux/generic/patches-3.0/100-overlayfs_v11.patch
@@ -1,3 +1,283 @@
+--- /dev/null
++++ b/Documentation/filesystems/overlayfs.txt
+@@ -0,0 +1,199 @@
++Written by: Neil Brown <neilb@suse.de>
++
++Overlay Filesystem
++==================
++
++This document describes a prototype for a new approach to providing
++overlay-filesystem functionality in Linux (sometimes referred to as
++union-filesystems).  An overlay-filesystem tries to present a
++filesystem which is the result over overlaying one filesystem on top
++of the other.
++
++The result will inevitably fail to look exactly like a normal
++filesystem for various technical reasons.  The expectation is that
++many use cases will be able to ignore these differences.
++
++This approach is 'hybrid' because the objects that appear in the
++filesystem do not all appear to belong to that filesystem.  In many
++cases an object accessed in the union will be indistinguishable
++from accessing the corresponding object from the original filesystem.
++This is most obvious from the 'st_dev' field returned by stat(2).
++
++While directories will report an st_dev from the overlay-filesystem,
++all non-directory objects will report an st_dev from the lower or
++upper filesystem that is providing the object.  Similarly st_ino will
++only be unique when combined with st_dev, and both of these can change
++over the lifetime of a non-directory object.  Many applications and
++tools ignore these values and will not be affected.
++
++Upper and Lower
++---------------
++
++An overlay filesystem combines two filesystems - an 'upper' filesystem
++and a 'lower' filesystem.  When a name exists in both filesystems, the
++object in the 'upper' filesystem is visible while the object in the
++'lower' filesystem is either hidden or, in the case of directories,
++merged with the 'upper' object.
++
++It would be more correct to refer to an upper and lower 'directory
++tree' rather than 'filesystem' as it is quite possible for both
++directory trees to be in the same filesystem and there is no
++requirement that the root of a filesystem be given for either upper or
++lower.
++
++The lower filesystem can be any filesystem supported by Linux and does
++not need to be writable.  The lower filesystem can even be another
++overlayfs.  The upper filesystem will normally be writable and if it
++is it must support the creation of trusted.* extended attributes, and
++must provide valid d_type in readdir responses, at least for symbolic
++links - so NFS is not suitable.
++
++A read-only overlay of two read-only filesystems may use any
++filesystem type.
++
++Directories
++-----------
++
++Overlaying mainly involved directories.  If a given name appears in both
++upper and lower filesystems and refers to a non-directory in either,
++then the lower object is hidden - the name refers only to the upper
++object.
++
++Where both upper and lower objects are directories, a merged directory
++is formed.
++
++At mount time, the two directories given as mount options are combined
++into a merged directory:
++
++  mount -t overlayfs overlayfs -olowerdir=/lower,upperdir=/upper /overlay
++
++Then whenever a lookup is requested in such a merged directory, the
++lookup is performed in each actual directory and the combined result
++is cached in the dentry belonging to the overlay filesystem.  If both
++actual lookups find directories, both are stored and a merged
++directory is created, otherwise only one is stored: the upper if it
++exists, else the lower.
++
++Only the lists of names from directories are merged.  Other content
++such as metadata and extended attributes are reported for the upper
++directory only.  These attributes of the lower directory are hidden.
++
++whiteouts and opaque directories
++--------------------------------
++
++In order to support rm and rmdir without changing the lower
++filesystem, an overlay filesystem needs to record in the upper filesystem
++that files have been removed.  This is done using whiteouts and opaque
++directories (non-directories are always opaque).
++
++The overlay filesystem uses extended attributes with a
++"trusted.overlay."  prefix to record these details.
++
++A whiteout is created as a symbolic link with target
++"(overlay-whiteout)" and with xattr "trusted.overlay.whiteout" set to "y".
++When a whiteout is found in the upper level of a merged directory, any
++matching name in the lower level is ignored, and the whiteout itself
++is also hidden.
++
++A directory is made opaque by setting the xattr "trusted.overlay.opaque"
++to "y".  Where the upper filesystem contains an opaque directory, any
++directory in the lower filesystem with the same name is ignored.
++
++readdir
++-------
++
++When a 'readdir' request is made on a merged directory, the upper and
++lower directories are each read and the name lists merged in the
++obvious way (upper is read first, then lower - entries that already
++exist are not re-added).  This merged name list is cached in the
++'struct file' and so remains as long as the file is kept open.  If the
++directory is opened and read by two processes at the same time, they
++will each have separate caches.  A seekdir to the start of the
++directory (offset 0) followed by a readdir will cause the cache to be
++discarded and rebuilt.
++
++This means that changes to the merged directory do not appear while a
++directory is being read.  This is unlikely to be noticed by many
++programs.
++
++seek offsets are assigned sequentially when the directories are read.
++Thus if
++  - read part of a directory
++  - remember an offset, and close the directory
++  - re-open the directory some time later
++  - seek to the remembered offset
++
++there may be little correlation between the old and new locations in
++the list of filenames, particularly if anything has changed in the
++directory.
++
++Readdir on directories that are not merged is simply handled by the
++underlying directory (upper or lower).
++
++
++Non-directories
++---------------
++
++Objects that are not directories (files, symlinks, device-special
++files etc.) are presented either from the upper or lower filesystem as
++appropriate.  When a file in the lower filesystem is accessed in a way
++the requires write-access, such as opening for write access, changing
++some metadata etc., the file is first copied from the lower filesystem
++to the upper filesystem (copy_up).  Note that creating a hard-link
++also requires copy_up, though of course creation of a symlink does
++not.
++
++The copy_up may turn out to be unnecessary, for example if the file is
++opened for read-write but the data is not modified.
++
++The copy_up process first makes sure that the containing directory
++exists in the upper filesystem - creating it and any parents as
++necessary.  It then creates the object with the same metadata (owner,
++mode, mtime, symlink-target etc.) and then if the object is a file, the
++data is copied from the lower to the upper filesystem.  Finally any
++extended attributes are copied up.
++
++Once the copy_up is complete, the overlay filesystem simply
++provides direct access to the newly created file in the upper
++filesystem - future operations on the file are barely noticed by the
++overlay filesystem (though an operation on the name of the file such as
++rename or unlink will of course be noticed and handled).
++
++
++Non-standard behavior
++---------------------
++
++The copy_up operation essentially creates a new, identical file and
++moves it over to the old name.  The new file may be on a different
++filesystem, so both st_dev and st_ino of the file may change.
++
++Any open files referring to this inode will access the old data and
++metadata.  Similarly any file locks obtained before copy_up will not
++apply to the copied up file.
++
++On a file is opened with O_RDONLY fchmod(2), fchown(2), futimesat(2)
++and fsetxattr(2) will fail with EROFS.
++
++If a file with multiple hard links is copied up, then this will
++"break" the link.  Changes will not be propagated to other names
++referring to the same inode.
++
++Symlinks in /proc/PID/ and /proc/PID/fd which point to a non-directory
++object in overlayfs will not contain vaid absolute paths, only
++relative paths leading up to the filesystem's root.  This will be
++fixed in the future.
++
++Some operations are not atomic, for example a crash during copy_up or
++rename will leave the filesystem in an inconsitent state.  This will
++be addressed in the future.
++
++Changes to underlying filesystems
++---------------------------------
++
++Offline changes, when the overlay is not mounted, are allowed to either
++the upper or the lower trees.
++
++Changes to the underlying filesystems while part of a mounted overlay
++filesystem are not allowed.  If the underlying filesystem is changed,
++the behavior of the overlay is undefined, though it will not result in
++a crash or deadlock.
+--- a/MAINTAINERS
++++ b/MAINTAINERS
+@@ -4727,6 +4727,13 @@ F:	drivers/scsi/osd/
+ F:	include/scsi/osd_*
+ F:	fs/exofs/
+ 
++OVERLAYFS FILESYSTEM
++M:	Miklos Szeredi <miklos@szeredi.hu>
++L:	linux-fsdevel@vger.kernel.org
++S:	Supported
++F:	fs/overlayfs/*
++F:	Documentation/filesystems/overlayfs.txt
++
+ P54 WIRELESS DRIVER
+ M:	Christian Lamparter <chunkeey@googlemail.com>
+ L:	linux-wireless@vger.kernel.org
+--- a/fs/Kconfig
++++ b/fs/Kconfig
+@@ -63,6 +63,7 @@ source "fs/quota/Kconfig"
+ 
+ source "fs/autofs4/Kconfig"
+ source "fs/fuse/Kconfig"
++source "fs/overlayfs/Kconfig"
+ 
+ config CUSE
+ 	tristate "Character device in Userspace support"
+--- a/fs/Makefile
++++ b/fs/Makefile
+@@ -105,6 +105,7 @@ obj-$(CONFIG_QNX4FS_FS)		+= qnx4/
+ obj-$(CONFIG_AUTOFS4_FS)	+= autofs4/
+ obj-$(CONFIG_ADFS_FS)		+= adfs/
+ obj-$(CONFIG_FUSE_FS)		+= fuse/
++obj-$(CONFIG_OVERLAYFS_FS)	+= overlayfs/
+ obj-$(CONFIG_UDF_FS)		+= udf/
+ obj-$(CONFIG_SUN_OPENPROMFS)	+= openpromfs/
+ obj-$(CONFIG_OMFS_FS)		+= omfs/
+--- a/fs/ecryptfs/main.c
++++ b/fs/ecryptfs/main.c
+@@ -544,6 +544,13 @@ static struct dentry *ecryptfs_mount(str
+ 	s->s_maxbytes = path.dentry->d_sb->s_maxbytes;
+ 	s->s_blocksize = path.dentry->d_sb->s_blocksize;
+ 	s->s_magic = ECRYPTFS_SUPER_MAGIC;
++	s->s_stack_depth = path.dentry->d_sb->s_stack_depth + 1;
++
++	rc = -EINVAL;
++	if (s->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
++		printk(KERN_ERR "eCryptfs: maximum fs stacking depth exceeded\n");
++		goto out_free;
++	}
+ 
+ 	inode = ecryptfs_get_inode(path.dentry->d_inode, s);
+ 	rc = PTR_ERR(inode);
+--- a/fs/namespace.c
++++ b/fs/namespace.c
+@@ -1492,6 +1492,23 @@ void drop_collected_mounts(struct vfsmou
+ 	release_mounts(&umount_list);
+ }
+ 
++struct vfsmount *clone_private_mount(struct path *path)
++{
++	struct vfsmount *mnt;
++
++	if (IS_MNT_UNBINDABLE(path->mnt))
++		return ERR_PTR(-EINVAL);
++
++	down_read(&namespace_sem);
++	mnt = clone_mnt(path->mnt, path->dentry, CL_PRIVATE);
++	up_read(&namespace_sem);
++	if (!mnt)
++		return ERR_PTR(-ENOMEM);
++
++	return mnt;
++}
++EXPORT_SYMBOL_GPL(clone_private_mount);
++
+ int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg,
+ 		   struct vfsmount *root)
+ {
 --- a/fs/open.c
 +++ b/fs/open.c
 @@ -666,8 +666,7 @@ static inline int __get_file_write_acces
@@ -154,92 +434,6 @@
  
  static void __put_unused_fd(struct files_struct *files, unsigned int fd)
  {
---- a/include/linux/fs.h
-+++ b/include/linux/fs.h
-@@ -1603,6 +1603,7 @@ struct inode_operations {
- 	void (*truncate_range)(struct inode *, loff_t, loff_t);
- 	int (*fiemap)(struct inode *, struct fiemap_extent_info *, u64 start,
- 		      u64 len);
-+	struct file *(*open)(struct dentry *, int flags, const struct cred *);
- } ____cacheline_aligned;
- 
- struct seq_file;
-@@ -1998,6 +1999,7 @@ extern long do_sys_open(int dfd, const c
- extern struct file *filp_open(const char *, int, int);
- extern struct file *file_open_root(struct dentry *, struct vfsmount *,
- 				   const char *, int);
-+extern struct file *vfs_open(struct path *, int flags, const struct cred *);
- extern struct file * dentry_open(struct dentry *, struct vfsmount *, int,
- 				 const struct cred *);
- extern int filp_close(struct file *, fl_owner_t id);
---- a/fs/splice.c
-+++ b/fs/splice.c
-@@ -1300,6 +1300,7 @@ long do_splice_direct(struct file *in, l
- 
- 	return ret;
- }
-+EXPORT_SYMBOL(do_splice_direct);
- 
- static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
- 			       struct pipe_inode_info *opipe,
---- a/fs/namespace.c
-+++ b/fs/namespace.c
-@@ -1492,6 +1492,23 @@ void drop_collected_mounts(struct vfsmou
- 	release_mounts(&umount_list);
- }
- 
-+struct vfsmount *clone_private_mount(struct path *path)
-+{
-+	struct vfsmount *mnt;
-+
-+	if (IS_MNT_UNBINDABLE(path->mnt))
-+		return ERR_PTR(-EINVAL);
-+
-+	down_read(&namespace_sem);
-+	mnt = clone_mnt(path->mnt, path->dentry, CL_PRIVATE);
-+	up_read(&namespace_sem);
-+	if (!mnt)
-+		return ERR_PTR(-ENOMEM);
-+
-+	return mnt;
-+}
-+EXPORT_SYMBOL_GPL(clone_private_mount);
-+
- int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg,
- 		   struct vfsmount *root)
- {
---- a/include/linux/mount.h
-+++ b/include/linux/mount.h
-@@ -100,6 +100,9 @@ extern void mnt_pin(struct vfsmount *mnt
- extern void mnt_unpin(struct vfsmount *mnt);
- extern int __mnt_is_readonly(struct vfsmount *mnt);
- 
-+struct path;
-+extern struct vfsmount *clone_private_mount(struct path *path);
-+
- extern struct vfsmount *do_kern_mount(const char *fstype, int flags,
- 				      const char *name, void *data);
- 
---- a/fs/Kconfig
-+++ b/fs/Kconfig
-@@ -63,6 +63,7 @@ source "fs/quota/Kconfig"
- 
- source "fs/autofs4/Kconfig"
- source "fs/fuse/Kconfig"
-+source "fs/overlayfs/Kconfig"
- 
- config CUSE
- 	tristate "Character device in Userspace support"
---- a/fs/Makefile
-+++ b/fs/Makefile
-@@ -105,6 +105,7 @@ obj-$(CONFIG_QNX4FS_FS)		+= qnx4/
- obj-$(CONFIG_AUTOFS4_FS)	+= autofs4/
- obj-$(CONFIG_ADFS_FS)		+= adfs/
- obj-$(CONFIG_FUSE_FS)		+= fuse/
-+obj-$(CONFIG_OVERLAYFS_FS)	+= overlayfs/
- obj-$(CONFIG_UDF_FS)		+= udf/
- obj-$(CONFIG_SUN_OPENPROMFS)	+= openpromfs/
- obj-$(CONFIG_OMFS_FS)		+= omfs/
 --- /dev/null
 +++ b/fs/overlayfs/Kconfig
 @@ -0,0 +1,4 @@
@@ -645,7 +839,7 @@
 +}
 --- /dev/null
 +++ b/fs/overlayfs/dir.c
-@@ -0,0 +1,607 @@
+@@ -0,0 +1,596 @@
 +/*
 + *
 + * Copyright (C) 2011 Novell Inc.
@@ -663,17 +857,6 @@
 +
 +static const char *ovl_whiteout_symlink = "(overlay-whiteout)";
 +
-+static struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
-+				 struct nameidata *nd)
-+{
-+	int err = ovl_do_lookup(dentry);
-+
-+	if (err)
-+		return ERR_PTR(err);
-+
-+	return NULL;
-+}
-+
 +static int ovl_whiteout(struct dentry *upperdir, struct dentry *dentry)
 +{
 +	int err;
@@ -1255,7 +1438,7 @@
 +};
 --- /dev/null
 +++ b/fs/overlayfs/inode.c
-@@ -0,0 +1,375 @@
+@@ -0,0 +1,384 @@
 +/*
 + *
 + * Copyright (C) 2011 Novell Inc.
@@ -1348,9 +1531,18 @@
 +		/*
 +		 * Writes will always be redirected to upper layer, so
 +		 * ignore lower layer being read-only.
++		 *
++		 * If the overlay itself is read-only then proceed
++		 * with the permission check, don't return EROFS.
++		 * This will only happen if this is the lower layer of
++		 * another overlayfs.
++		 *
++		 * If upper fs becomes read-only after the overlay was
++		 * constructed return EROFS to prevent modification of
++		 * upper layer.
 +		 */
 +		err = -EROFS;
-+		if (is_upper && IS_RDONLY(realinode) &&
++		if (is_upper && !IS_RDONLY(inode) && IS_RDONLY(realinode) &&
 +		    (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
 +			goto out_dput;
 +
@@ -1633,7 +1825,7 @@
 +}
 --- /dev/null
 +++ b/fs/overlayfs/overlayfs.h
-@@ -0,0 +1,62 @@
+@@ -0,0 +1,63 @@
 +/*
 + *
 + * Copyright (C) 2011 Novell Inc.
@@ -1669,7 +1861,8 @@
 +void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque);
 +bool ovl_is_whiteout(struct dentry *dentry);
 +void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry);
-+int ovl_do_lookup(struct dentry *dentry);
++struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
++			  struct nameidata *nd);
 +
 +struct dentry *ovl_upper_create(struct dentry *upperdir, struct dentry *dentry,
 +				struct kstat *stat, const char *link);
@@ -1866,8 +2059,8 @@
 +	return ovl_cache_entry_add_rb(rdd, name, namelen, ino, d_type);
 +}
 +
-+static int ovl_dir_read(struct path *realpath, struct ovl_readdir_data *rdd,
-+			  filldir_t filler)
++static inline int ovl_dir_read(struct path *realpath,
++			       struct ovl_readdir_data *rdd, filldir_t filler)
 +{
 +	struct file *realfile;
 +	int err;
@@ -1947,7 +2140,7 @@
 +	return 0;
 +}
 +
-+static int ovl_dir_read_merged(struct path *upperpath, struct path *lowerpath,
++static inline int ovl_dir_read_merged(struct path *upperpath, struct path *lowerpath,
 +			       struct ovl_readdir_data *rdd)
 +{
 +	int err;
@@ -2259,7 +2452,7 @@
 +}
 --- /dev/null
 +++ b/fs/overlayfs/super.c
-@@ -0,0 +1,625 @@
+@@ -0,0 +1,656 @@
 +/*
 + *
 + * Copyright (C) 2011 Novell Inc.
@@ -2510,7 +2703,7 @@
 +	return kzalloc(sizeof(struct ovl_entry), GFP_KERNEL);
 +}
 +
-+static struct dentry *ovl_lookup_real(struct dentry *dir, struct qstr *name)
++static inline struct dentry *ovl_lookup_real(struct dentry *dir, struct qstr *name)
 +{
 +	struct dentry *dentry;
 +
@@ -2528,7 +2721,7 @@
 +	return dentry;
 +}
 +
-+int ovl_do_lookup(struct dentry *dentry)
++static int ovl_do_lookup(struct dentry *dentry)
 +{
 +	struct ovl_entry *oe;
 +	struct dentry *upperdir;
@@ -2625,6 +2818,17 @@
 +	return err;
 +}
 +
++struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
++			  struct nameidata *nd)
++{
++	int err = ovl_do_lookup(dentry);
++
++	if (err)
++		return ERR_PTR(err);
++
++	return NULL;
++}
++
 +static void ovl_put_super(struct super_block *sb)
 +{
 +	struct ovl_fs *ufs = sb->s_fs_info;
@@ -2796,6 +3000,16 @@
 +	    !S_ISDIR(lowerpath.dentry->d_inode->i_mode))
 +		goto out_put_lowerpath;
 +
++	sb->s_stack_depth = max(upperpath.mnt->mnt_sb->s_stack_depth,
++				lowerpath.mnt->mnt_sb->s_stack_depth) + 1;
++
++	err = -EINVAL;
++	if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
++		printk(KERN_ERR "overlayfs: maximum fs stacking depth exceeded\n");
++		goto out_put_lowerpath;
++	}
++
++
 +	ufs->upper_mnt = clone_private_mount(&upperpath);
 +	err = PTR_ERR(ufs->upper_mnt);
 +	if (IS_ERR(ufs->upper_mnt)) {
@@ -2810,6 +3024,16 @@
 +		goto out_put_upper_mnt;
 +	}
 +
++	/*
++	 * Make lower_mnt R/O.  That way fchmod/fchown on lower file
++	 * will fail instead of modifying lower fs.
++	 */
++	ufs->lower_mnt->mnt_flags |= MNT_READONLY;
++
++	/* If the upper fs is r/o, we mark overlayfs r/o too */
++	if (ufs->upper_mnt->mnt_sb->s_flags & MS_RDONLY)
++		sb->s_flags |= MS_RDONLY;
++
 +	if (!(sb->s_flags & MS_RDONLY)) {
 +		err = mnt_want_write(ufs->upper_mnt);
 +		if (err)
@@ -2885,189 +3109,68 @@
 +
 +module_init(ovl_init);
 +module_exit(ovl_exit);
---- /dev/null
-+++ b/Documentation/filesystems/overlayfs.txt
-@@ -0,0 +1,167 @@
-+Written by: Neil Brown <neilb@suse.de>
-+
-+Overlay Filesystem
-+==================
-+
-+This document describes a prototype for a new approach to providing
-+overlay-filesystem functionality in Linux (sometimes referred to as
-+union-filesystems).  An overlay-filesystem tries to present a
-+filesystem which is the result over overlaying one filesystem on top
-+of the other.
-+
-+The result will inevitably fail to look exactly like a normal
-+filesystem for various technical reasons.  The expectation is that
-+many use cases will be able to ignore these differences.
-+
-+This approach is 'hybrid' because the objects that appear in the
-+filesystem do not all appear to belong to that filesystem.  In many
-+cases an object accessed in the union will be indistinguishable
-+from accessing the corresponding object from the original filesystem.
-+This is most obvious from the 'st_dev' field returned by stat(2).
-+
-+While directories will report an st_dev from the overlay-filesystem,
-+all non-directory objects will report an st_dev from the lower or
-+upper filesystem that is providing the object.  Similarly st_ino will
-+only be unique when combined with st_dev, and both of these can change
-+over the lifetime of a non-directory object.  Many applications and
-+tools ignore these values and will not be affected.
-+
-+Upper and Lower
-+---------------
-+
-+An overlay filesystem combines two filesystems - an 'upper' filesystem
-+and a 'lower' filesystem.  When a name exists in both filesystems, the
-+object in the 'upper' filesystem is visible while the object in the
-+'lower' filesystem is either hidden or, in the case of directories,
-+merged with the 'upper' object.
-+
-+It would be more correct to refer to an upper and lower 'directory
-+tree' rather than 'filesystem' as it is quite possible for both
-+directory trees to be in the same filesystem and there is no
-+requirement that the root of a filesystem be given for either upper or
-+lower.
-+
-+The lower filesystem can be any filesystem supported by Linux and does
-+not need to be writable.  The lower filesystem can even be another
-+overlayfs.  The upper filesystem will normally be writable and if it
-+is it must support the creation of trusted.* extended attributes, and
-+must provide valid d_type in readdir responses, at least for symbolic
-+links - so NFS is not suitable.
-+
-+A read-only overlay of two read-only filesystems may use any
-+filesystem type.
-+
-+Directories
-+-----------
-+
-+Overlaying mainly involved directories.  If a given name appears in both
-+upper and lower filesystems and refers to a non-directory in either,
-+then the lower object is hidden - the name refers only to the upper
-+object.
-+
-+Where both upper and lower objects are directories, a merged directory
-+is formed.
-+
-+At mount time, the two directories given as mount options are combined
-+into a merged directory:
-+
-+  mount -t overlayfs overlayfs -olowerdir=/lower,upperdir=/upper /overlay
-+
-+Then whenever a lookup is requested in such a merged directory, the
-+lookup is performed in each actual directory and the combined result
-+is cached in the dentry belonging to the overlay filesystem.  If both
-+actual lookups find directories, both are stored and a merged
-+directory is created, otherwise only one is stored: the upper if it
-+exists, else the lower.
-+
-+Only the lists of names from directories are merged.  Other content
-+such as metadata and extended attributes are reported for the upper
-+directory only.  These attributes of the lower directory are hidden.
-+
-+whiteouts and opaque directories
-+--------------------------------
-+
-+In order to support rm and rmdir without changing the lower
-+filesystem, an overlay filesystem needs to record in the upper filesystem
-+that files have been removed.  This is done using whiteouts and opaque
-+directories (non-directories are always opaque).
-+
-+The overlay filesystem uses extended attributes with a
-+"trusted.overlay."  prefix to record these details.
-+
-+A whiteout is created as a symbolic link with target
-+"(overlay-whiteout)" and with xattr "trusted.overlay.whiteout" set to "y".
-+When a whiteout is found in the upper level of a merged directory, any
-+matching name in the lower level is ignored, and the whiteout itself
-+is also hidden.
-+
-+A directory is made opaque by setting the xattr "trusted.overlay.opaque"
-+to "y".  Where the upper filesystem contains an opaque directory, any
-+directory in the lower filesystem with the same name is ignored.
-+
-+readdir
-+-------
-+
-+When a 'readdir' request is made on a merged directory, the upper and
-+lower directories are each read and the name lists merged in the
-+obvious way (upper is read first, then lower - entries that already
-+exist are not re-added).  This merged name list is cached in the
-+'struct file' and so remains as long as the file is kept open.  If the
-+directory is opened and read by two processes at the same time, they
-+will each have separate caches.  A seekdir to the start of the
-+directory (offset 0) followed by a readdir will cause the cache to be
-+discarded and rebuilt.
-+
-+This means that changes to the merged directory do not appear while a
-+directory is being read.  This is unlikely to be noticed by many
-+programs.
-+
-+seek offsets are assigned sequentially when the directories are read.
-+Thus if
-+  - read part of a directory
-+  - remember an offset, and close the directory
-+  - re-open the directory some time later
-+  - seek to the remembered offset
-+
-+there may be little correlation between the old and new locations in
-+the list of filenames, particularly if anything has changed in the
-+directory.
-+
-+Readdir on directories that are not merged is simply handled by the
-+underlying directory (upper or lower).
-+
-+
-+Non-directories
-+---------------
-+
-+Objects that are not directories (files, symlinks, device-special
-+files etc.) are presented either from the upper or lower filesystem as
-+appropriate.  When a file in the lower filesystem is accessed in a way
-+the requires write-access, such as opening for write access, changing
-+some metadata etc., the file is first copied from the lower filesystem
-+to the upper filesystem (copy_up).  Note that creating a hard-link
-+also requires copy_up, though of course creation of a symlink does
-+not.
-+
-+The copy_up process first makes sure that the containing directory
-+exists in the upper filesystem - creating it and any parents as
-+necessary.  It then creates the object with the same metadata (owner,
-+mode, mtime, symlink-target etc.) and then if the object is a file, the
-+data is copied from the lower to the upper filesystem.  Finally any
-+extended attributes are copied up.
-+
-+Once the copy_up is complete, the overlay filesystem simply
-+provides direct access to the newly created file in the upper
-+filesystem - future operations on the file are barely noticed by the
-+overlay filesystem (though an operation on the name of the file such as
-+rename or unlink will of course be noticed and handled).
-+
-+Changes to underlying filesystems
-+---------------------------------
+--- a/fs/splice.c
++++ b/fs/splice.c
+@@ -1300,6 +1300,7 @@ long do_splice_direct(struct file *in, l
+ 
+ 	return ret;
+ }
++EXPORT_SYMBOL(do_splice_direct);
+ 
+ static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
+ 			       struct pipe_inode_info *opipe,
+--- a/include/linux/fs.h
++++ b/include/linux/fs.h
+@@ -480,6 +480,12 @@ struct iattr {
+  */
+ #include <linux/quota.h>
+ 
++/*
++ * Maximum number of layers of fs stack.  Needs to be limited to
++ * prevent kernel stack overflow
++ */
++#define FILESYSTEM_MAX_STACK_DEPTH 2
 +
-+Offline changes, when the overlay is not mounted, are allowed to either
-+the upper or the lower trees.
+ /** 
+  * enum positive_aop_returns - aop return codes with specific semantics
+  *
+@@ -1438,6 +1444,11 @@ struct super_block {
+ 	 * Saved pool identifier for cleancache (-1 means none)
+ 	 */
+ 	int cleancache_poolid;
 +
-+Changes to the underlying filesystems while part of a mounted overlay
-+filesystem are not allowed.  This is not yet enforced, but will be in
-+the future.
---- a/MAINTAINERS
-+++ b/MAINTAINERS
-@@ -4727,6 +4727,13 @@ F:	drivers/scsi/osd/
- F:	include/scsi/osd_*
- F:	fs/exofs/
++	/*
++	 * Indicates how deep in a filesystem stack this SB is
++	 */
++	int s_stack_depth;
+ };
  
-+OVERLAYFS FILESYSTEM
-+M:	Miklos Szeredi <miklos@szeredi.hu>
-+L:	linux-fsdevel@vger.kernel.org
-+S:	Supported
-+F:	fs/overlayfs/*
-+F:	Documentation/filesystems/overlayfs.txt
+ extern struct timespec current_fs_time(struct super_block *sb);
+@@ -1603,6 +1614,7 @@ struct inode_operations {
+ 	void (*truncate_range)(struct inode *, loff_t, loff_t);
+ 	int (*fiemap)(struct inode *, struct fiemap_extent_info *, u64 start,
+ 		      u64 len);
++	struct file *(*open)(struct dentry *, int flags, const struct cred *);
+ } ____cacheline_aligned;
+ 
+ struct seq_file;
+@@ -1998,6 +2010,7 @@ extern long do_sys_open(int dfd, const c
+ extern struct file *filp_open(const char *, int, int);
+ extern struct file *file_open_root(struct dentry *, struct vfsmount *,
+ 				   const char *, int);
++extern struct file *vfs_open(struct path *, int flags, const struct cred *);
+ extern struct file * dentry_open(struct dentry *, struct vfsmount *, int,
+ 				 const struct cred *);
+ extern int filp_close(struct file *, fl_owner_t id);
+--- a/include/linux/mount.h
++++ b/include/linux/mount.h
+@@ -100,6 +100,9 @@ extern void mnt_pin(struct vfsmount *mnt
+ extern void mnt_unpin(struct vfsmount *mnt);
+ extern int __mnt_is_readonly(struct vfsmount *mnt);
+ 
++struct path;
++extern struct vfsmount *clone_private_mount(struct path *path);
 +
- P54 WIRELESS DRIVER
- M:	Christian Lamparter <chunkeey@googlemail.com>
- L:	linux-wireless@vger.kernel.org
+ extern struct vfsmount *do_kern_mount(const char *fstype, int flags,
+ 				      const char *name, void *data);
+