kernel: remove linux 3.8 support

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

SVN-Revision: 44890

1 files changed, 0 insertions, 3191 deletions

diff --git a/target/linux/generic/patches-3.8/100-overlayfs.patch b/target/linux/generic/patches-3.8/100-overlayfs.patch
deleted file mode 100644
index 26f373d1eb..0000000000
--- a/target/linux/generic/patches-3.8/100-overlayfs.patch
+++ /dev/null
@@ -1,3191 +0,0 @@
---- a/Documentation/filesystems/Locking
-+++ b/Documentation/filesystems/Locking
-@@ -64,6 +64,7 @@ prototypes:
- 	int (*atomic_open)(struct inode *, struct dentry *,
- 				struct file *, unsigned open_flag,
- 				umode_t create_mode, int *opened);
-+	int (*dentry_open)(struct dentry *, struct file *, const struct cred *);
- 
- locking rules:
- 	all may block
-@@ -91,6 +92,7 @@ removexattr:	yes
- fiemap:		no
- update_time:	no
- atomic_open:	yes
-+dentry_open:	no
- 
- 	Additionally, ->rmdir(), ->unlink() and ->rename() have ->i_mutex on
- victim.
---- /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 involves 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 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 valid 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 inconsistent 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/Documentation/filesystems/vfs.txt
-+++ b/Documentation/filesystems/vfs.txt
-@@ -362,6 +362,7 @@ struct inode_operations {
- 	int (*atomic_open)(struct inode *, struct dentry *,
- 				struct file *, unsigned open_flag,
- 				umode_t create_mode, int *opened);
-+	int (*dentry_open)(struct dentry *, struct file *, const struct cred *);
- };
- 
- Again, all methods are called without any locks being held, unless
-@@ -681,6 +682,12 @@ struct address_space_operations {
-   	but instead uses bmap to find out where the blocks in the file
-   	are and uses those addresses directly.
- 
-+  dentry_open: this is an alternative to f_op->open(), the difference is that
-+	this method may open a file not necessarily originating from the same
-+	filesystem as the one i_op->open() was called on.  It may be
-+	useful for stacking filesystems which want to allow native I/O directly
-+	on underlying files.
-+
- 
-   invalidatepage: If a page has PagePrivate set, then invalidatepage
-         will be called when part or all of the page is to be removed
---- a/fs/ecryptfs/main.c
-+++ b/fs/ecryptfs/main.c
-@@ -567,6 +567,13 @@ 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/internal.h
-+++ b/fs/internal.h
-@@ -42,11 +42,6 @@ static inline int __sync_blockdev(struct
- extern void __init chrdev_init(void);
- 
- /*
-- * namei.c
-- */
--extern int __inode_permission(struct inode *, int);
--
--/*
-  * namespace.c
-  */
- extern int copy_mount_options(const void __user *, unsigned long *);
---- a/fs/Kconfig
-+++ b/fs/Kconfig
-@@ -67,6 +67,7 @@ source "fs/quota/Kconfig"
- 
- source "fs/autofs4/Kconfig"
- source "fs/fuse/Kconfig"
-+source "fs/overlayfs/Kconfig"
- 
- config GENERIC_ACL
- 	bool
---- a/fs/Makefile
-+++ b/fs/Makefile
-@@ -107,6 +107,7 @@ obj-$(CONFIG_QNX6FS_FS)		+= qnx6/
- obj-$(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/namei.c
-+++ b/fs/namei.c
-@@ -402,6 +402,7 @@ int __inode_permission(struct inode *ino
- 
- 	return security_inode_permission(inode, mask);
- }
-+EXPORT_SYMBOL(__inode_permission);
- 
- /**
-  * sb_permission - Check superblock-level permissions
-@@ -2876,9 +2877,12 @@ finish_open_created:
- 	error = may_open(&nd->path, acc_mode, open_flag);
- 	if (error)
- 		goto out;
--	file->f_path.mnt = nd->path.mnt;
--	error = finish_open(file, nd->path.dentry, NULL, opened);
--	if (error) {
-+
-+	BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */
-+	error = vfs_open(&nd->path, file, current_cred());
-+	if (!error) {
-+		*opened |= FILE_OPENED;
-+	} else {
- 		if (error == -EOPENSTALE)
- 			goto stale_open;
- 		goto out;
---- a/fs/namespace.c
-+++ b/fs/namespace.c
-@@ -1421,6 +1421,24 @@ void drop_collected_mounts(struct vfsmou
- 	release_mounts(&umount_list);
- }
- 
-+struct vfsmount *clone_private_mount(struct path *path)
-+{
-+	struct mount *old_mnt = real_mount(path->mnt);
-+	struct mount *new_mnt;
-+
-+	if (IS_MNT_UNBINDABLE(old_mnt))
-+		return ERR_PTR(-EINVAL);
-+
-+	down_read(&namespace_sem);
-+	new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE);
-+	up_read(&namespace_sem);
-+	if (!new_mnt)
-+		return ERR_PTR(-ENOMEM);
-+
-+	return &new_mnt->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
-@@ -816,8 +816,7 @@ struct file *dentry_open(const struct pa
- 		return ERR_PTR(error);
- 
- 	f->f_flags = flags;
--	f->f_path = *path;
--	error = do_dentry_open(f, NULL, cred);
-+	error = vfs_open(path, f, cred);
- 	if (!error) {
- 		error = open_check_o_direct(f);
- 		if (error) {
-@@ -832,6 +831,26 @@ struct file *dentry_open(const struct pa
- }
- EXPORT_SYMBOL(dentry_open);
- 
-+/**
-+ * vfs_open - open the file at the given path
-+ * @path: path to open
-+ * @filp: newly allocated file with f_flag initialized
-+ * @cred: credentials to use
-+ */
-+int vfs_open(const struct path *path, struct file *filp,
-+	     const struct cred *cred)
-+{
-+	struct inode *inode = path->dentry->d_inode;
-+
-+	if (inode->i_op->dentry_open)
-+		return inode->i_op->dentry_open(path->dentry, filp, cred);
-+	else {
-+		filp->f_path = *path;
-+		return do_dentry_open(filp, NULL, cred);
-+	}
-+}
-+EXPORT_SYMBOL(vfs_open);
-+
- static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op)
- {
- 	int lookup_flags = 0;
---- /dev/null
-+++ b/fs/overlayfs/copy_up.c
-@@ -0,0 +1,385 @@
-+/*
-+ *
-+ * 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/file.h>
-+#include <linux/splice.h>
-+#include <linux/xattr.h>
-+#include <linux/security.h>
-+#include <linux/uaccess.h>
-+#include <linux/sched.h>
-+#include "overlayfs.h"
-+
-+#define OVL_COPY_UP_CHUNK_SIZE (1 << 20)
-+
-+static int ovl_copy_up_xattr(struct dentry *old, struct dentry *new)
-+{
-+	ssize_t list_size, size;
-+	char *buf, *name, *value;
-+	int error;
-+
-+	if (!old->d_inode->i_op->getxattr ||
-+	    !new->d_inode->i_op->getxattr)
-+		return 0;
-+
-+	list_size = vfs_listxattr(old, NULL, 0);
-+	if (list_size <= 0) {
-+		if (list_size == -EOPNOTSUPP)
-+			return 0;
-+		return list_size;
-+	}
-+
-+	buf = kzalloc(list_size, GFP_KERNEL);
-+	if (!buf)
-+		return -ENOMEM;
-+
-+	error = -ENOMEM;
-+	value = kmalloc(XATTR_SIZE_MAX, GFP_KERNEL);
-+	if (!value)
-+		goto out;
-+
-+	list_size = vfs_listxattr(old, buf, list_size);
-+	if (list_size <= 0) {
-+		error = list_size;
-+		goto out_free_value;
-+	}
-+
-+	for (name = buf; name < (buf + list_size); name += strlen(name) + 1) {
-+		size = vfs_getxattr(old, name, value, XATTR_SIZE_MAX);
-+		if (size <= 0) {
-+			error = size;
-+			goto out_free_value;
-+		}
-+		error = vfs_setxattr(new, name, value, size, 0);
-+		if (error)
-+			goto out_free_value;
-+	}
-+
-+out_free_value:
-+	kfree(value);
-+out:
-+	kfree(buf);
-+	return error;
-+}
-+
-+static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len)
-+{
-+	struct file *old_file;
-+	struct file *new_file;
-+	int error = 0;
-+
-+	if (len == 0)
-+		return 0;
-+
-+	old_file = ovl_path_open(old, O_RDONLY);
-+	if (IS_ERR(old_file))
-+		return PTR_ERR(old_file);
-+
-+	new_file = ovl_path_open(new, O_WRONLY);
-+	if (IS_ERR(new_file)) {
-+		error = PTR_ERR(new_file);
-+		goto out_fput;
-+	}
-+
-+	/* FIXME: copy up sparse files efficiently */
-+	while (len) {
-+		loff_t offset = new_file->f_pos;
-+		size_t this_len = OVL_COPY_UP_CHUNK_SIZE;
-+		long bytes;
-+
-+		if (len < this_len)
-+			this_len = len;
-+
-+		if (signal_pending_state(TASK_KILLABLE, current)) {
-+			error = -EINTR;
-+			break;
-+		}
-+
-+		bytes = do_splice_direct(old_file, &offset, new_file, this_len,
-+				 SPLICE_F_MOVE);
-+		if (bytes <= 0) {
-+			error = bytes;
-+			break;
-+		}
-+
-+		len -= bytes;
-+	}
-+
-+	fput(new_file);
-+out_fput:
-+	fput(old_file);
-+	return error;
-+}
-+
-+static char *ovl_read_symlink(struct dentry *realdentry)
-+{
-+	int res;
-+	char *buf;
-+	struct inode *inode = realdentry->d_inode;
-+	mm_segment_t old_fs;
-+
-+	res = -EINVAL;
-+	if (!inode->i_op->readlink)
-+		goto err;
-+
-+	res = -ENOMEM;
-+	buf = (char *) __get_free_page(GFP_KERNEL);
-+	if (!buf)
-+		goto err;
-+
-+	old_fs = get_fs();
-+	set_fs(get_ds());
-+	/* The cast to a user pointer is valid due to the set_fs() */
-+	res = inode->i_op->readlink(realdentry,
-+				    (char __user *)buf, PAGE_SIZE - 1);
-+	set_fs(old_fs);
-+	if (res < 0) {
-+		free_page((unsigned long) buf);
-+		goto err;
-+	}
-+	buf[res] = '\0';
-+
-+	return buf;
-+
-+err:
-+	return ERR_PTR(res);
-+}
-+
-+static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)
-+{
-+	struct iattr attr = {
-+		.ia_valid =
-+		     ATTR_ATIME | ATTR_MTIME | ATTR_ATIME_SET | ATTR_MTIME_SET,
-+		.ia_atime = stat->atime,
-+		.ia_mtime = stat->mtime,
-+	};
-+
-+	return notify_change(upperdentry, &attr);
-+}
-+
-+static int ovl_set_mode(struct dentry *upperdentry, umode_t mode)
-+{
-+	struct iattr attr = {
-+		.ia_valid = ATTR_MODE,
-+		.ia_mode = mode,
-+	};
-+
-+	return notify_change(upperdentry, &attr);
-+}
-+
-+static int ovl_copy_up_locked(struct dentry *upperdir, struct dentry *dentry,
-+			      struct path *lowerpath, struct kstat *stat,
-+			      const char *link)
-+{
-+	int err;
-+	struct path newpath;
-+	umode_t mode = stat->mode;
-+
-+	/* Can't properly set mode on creation because of the umask */
-+	stat->mode &= S_IFMT;
-+
-+	ovl_path_upper(dentry, &newpath);
-+	WARN_ON(newpath.dentry);
-+	newpath.dentry = ovl_upper_create(upperdir, dentry, stat, link);
-+	if (IS_ERR(newpath.dentry))
-+		return PTR_ERR(newpath.dentry);
-+
-+	if (S_ISREG(stat->mode)) {
-+		err = ovl_copy_up_data(lowerpath, &newpath, stat->size);
-+		if (err)
-+			goto err_remove;
-+	}
-+
-+	err = ovl_copy_up_xattr(lowerpath->dentry, newpath.dentry);
-+	if (err)
-+		goto err_remove;
-+
-+	mutex_lock(&newpath.dentry->d_inode->i_mutex);
-+	if (!S_ISLNK(stat->mode))
-+		err = ovl_set_mode(newpath.dentry, mode);
-+	if (!err)
-+		err = ovl_set_timestamps(newpath.dentry, stat);
-+	mutex_unlock(&newpath.dentry->d_inode->i_mutex);
-+	if (err)
-+		goto err_remove;
-+
-+	ovl_dentry_update(dentry, newpath.dentry);
-+
-+	/*
-+	 * Easiest way to get rid of the lower dentry reference is to
-+	 * drop this dentry.  This is neither needed nor possible for
-+	 * directories.
-+	 */
-+	if (!S_ISDIR(stat->mode))
-+		d_drop(dentry);
-+
-+	return 0;
-+
-+err_remove:
-+	if (S_ISDIR(stat->mode))
-+		vfs_rmdir(upperdir->d_inode, newpath.dentry);
-+	else
-+		vfs_unlink(upperdir->d_inode, newpath.dentry);
-+
-+	dput(newpath.dentry);
-+
-+	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)
-+{
-+	int err;
-+	struct kstat pstat;
-+	struct path parentpath;
-+	struct dentry *upperdir;
-+	const struct cred *old_cred;
-+	struct cred *override_cred;
-+	char *link = NULL;
-+
-+	ovl_path_upper(parent, &parentpath);
-+	upperdir = parentpath.dentry;
-+
-+	err = vfs_getattr(parentpath.mnt, parentpath.dentry, &pstat);
-+	if (err)
-+		return err;
-+
-+	if (S_ISLNK(stat->mode)) {
-+		link = ovl_read_symlink(lowerpath->dentry);
-+		if (IS_ERR(link))
-+			return PTR_ERR(link);
-+	}
-+
-+	err = -ENOMEM;
-+	override_cred = prepare_creds();
-+	if (!override_cred)
-+		goto out_free_link;
-+
-+	override_cred->fsuid = stat->uid;
-+	override_cred->fsgid = stat->gid;
-+	/*
-+	 * CAP_SYS_ADMIN for copying up extended attributes
-+	 * CAP_DAC_OVERRIDE for create
-+	 * CAP_FOWNER for chmod, timestamp update
-+	 * CAP_FSETID for chmod
-+	 * CAP_MKNOD for mknod
-+	 */
-+	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);
-+	cap_raise(override_cred->cap_effective, CAP_FSETID);
-+	cap_raise(override_cred->cap_effective, CAP_MKNOD);
-+	old_cred = override_creds(override_cred);
-+
-+	mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT);
-+	if (ovl_path_type(dentry) != OVL_PATH_LOWER) {
-+		err = 0;
-+	} else {
-+		err = ovl_copy_up_locked(upperdir, dentry, lowerpath,
-+					 stat, link);
-+		if (!err) {
-+			/* Restore timestamps on parent (best effort) */
-+			ovl_set_timestamps(upperdir, &pstat);
-+		}
-+	}
-+
-+	mutex_unlock(&upperdir->d_inode->i_mutex);
-+
-+	revert_creds(old_cred);
-+	put_cred(override_cred);
-+
-+out_free_link:
-+	if (link)
-+		free_page((unsigned long) link);
-+
-+	return err;
-+}
-+
-+int ovl_copy_up(struct dentry *dentry)
-+{
-+	int err;
-+
-+	err = 0;
-+	while (!err) {
-+		struct dentry *next;
-+		struct dentry *parent;
-+		struct path lowerpath;
-+		struct kstat stat;
-+		enum ovl_path_type type = ovl_path_type(dentry);
-+
-+		if (type != OVL_PATH_LOWER)
-+			break;
-+
-+		next = dget(dentry);
-+		/* find the topmost dentry not yet copied up */
-+		for (;;) {
-+			parent = dget_parent(next);
-+
-+			type = ovl_path_type(parent);
-+			if (type != OVL_PATH_LOWER)
-+				break;
-+
-+			dput(next);
-+			next = parent;
-+		}
-+
-+		ovl_path_lower(next, &lowerpath);
-+		err = vfs_getattr(lowerpath.mnt, lowerpath.dentry, &stat);
-+		if (!err)
-+			err = ovl_copy_up_one(parent, next, &lowerpath, &stat);
-+
-+		dput(parent);
-+		dput(next);
-+	}
-+
-+	return err;
-+}
-+
-+/* Optimize by not copying up the file first and truncating later */
-+int ovl_copy_up_truncate(struct dentry *dentry, loff_t size)
-+{
-+	int err;
-+	struct kstat stat;
-+	struct path lowerpath;
-+	struct dentry *parent = dget_parent(dentry);
-+
-+	err = ovl_copy_up(parent);
-+	if (err)
-+		goto out_dput_parent;
-+
-+	ovl_path_lower(dentry, &lowerpath);
-+	err = vfs_getattr(lowerpath.mnt, lowerpath.dentry, &stat);
-+	if (err)
-+		goto out_dput_parent;
-+
-+	if (size < stat.size)
-+		stat.size = size;
-+
-+	err = ovl_copy_up_one(parent, dentry, &lowerpath, &stat);
-+
-+out_dput_parent:
-+	dput(parent);
-+	return err;
-+}
---- /dev/null
-+++ b/fs/overlayfs/dir.c
-@@ -0,0 +1,604 @@
-+/*
-+ *
-+ * 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/cred.h>
-+#include "overlayfs.h"
-+
-+static const char *ovl_whiteout_symlink = "(overlay-whiteout)";
-+
-+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_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 = GLOBAL_ROOT_UID;
-+	override_cred->fsgid = GLOBAL_ROOT_GID;
-+	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_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);
-+}
-+
-+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,
-+			 struct kstat *stat)
-+{
-+	int err;
-+	enum ovl_path_type type;
-+	struct path realpath;
-+
-+	type = ovl_path_real(dentry, &realpath);
-+	err = vfs_getattr(realpath.mnt, realpath.dentry, stat);
-+	if (err)
-+		return err;
-+
-+	stat->dev = dentry->d_sb->s_dev;
-+	stat->ino = dentry->d_inode->i_ino;
-+
-+	/*
-+	 * It's probably not worth it to count subdirs to get the
-+	 * correct link count.  nlink=1 seems to pacify 'find' and
-+	 * other utilities.
-+	 */
-+	if (type == OVL_PATH_MERGE)
-+		stat->nlink = 1;
-+
-+	return 0;
-+}
-+
-+static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
-+			     const char *link)
-+{
-+	int err;
-+	struct dentry *newdentry;
-+	struct dentry *upperdir;
-+	struct inode *inode;
-+	struct kstat stat = {
-+		.mode = mode,
-+		.rdev = rdev,
-+	};
-+
-+	err = -ENOMEM;
-+	inode = ovl_new_inode(dentry->d_sb, mode, dentry->d_fsdata);
-+	if (!inode)
-+		goto out;
-+
-+	err = ovl_copy_up(dentry->d_parent);
-+	if (err)
-+		goto out_iput;
-+
-+	upperdir = ovl_dentry_upper(dentry->d_parent);
-+	mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT);
-+
-+	newdentry = ovl_upper_create(upperdir, dentry, &stat, link);
-+	err = PTR_ERR(newdentry);
-+	if (IS_ERR(newdentry))
-+		goto out_unlock;
-+
-+	ovl_dentry_version_inc(dentry->d_parent);
-+	if (ovl_dentry_is_opaque(dentry) && S_ISDIR(mode)) {
-+		err = ovl_set_opaque(newdentry);
-+		if (err) {
-+			vfs_rmdir(upperdir->d_inode, newdentry);
-+			ovl_whiteout(upperdir, dentry);
-+			goto out_dput;
-+		}
-+	}
-+	ovl_dentry_update(dentry, newdentry);
-+	ovl_copyattr(newdentry->d_inode, inode);
-+	d_instantiate(dentry, inode);
-+	inode = NULL;
-+	newdentry = NULL;
-+	err = 0;
-+
-+out_dput:
-+	dput(newdentry);
-+out_unlock:
-+	mutex_unlock(&upperdir->d_inode->i_mutex);
-+out_iput:
-+	iput(inode);
-+out:
-+	return err;
-+}
-+
-+static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode,
-+		      bool excl)
-+{
-+	return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL);
-+}
-+
-+static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
-+{
-+	return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL);
-+}
-+
-+static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
-+		     dev_t rdev)
-+{
-+	return ovl_create_object(dentry, mode, rdev, NULL);
-+}
-+
-+static int ovl_symlink(struct inode *dir, struct dentry *dentry,
-+			 const char *link)
-+{
-+	return ovl_create_object(dentry, S_IFLNK, 0, link);
-+}
-+
-+static int ovl_do_remove(struct dentry *dentry, bool is_dir)
-+{
-+	int err;
-+	enum ovl_path_type type;
-+	struct path realpath;
-+	struct dentry *upperdir;
-+
-+	err = ovl_copy_up(dentry->d_parent);
-+	if (err)
-+		return err;
-+
-+	upperdir = ovl_dentry_upper(dentry->d_parent);
-+	mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT);
-+	type = ovl_path_real(dentry, &realpath);
-+	if (type != OVL_PATH_LOWER) {
-+		err = -ESTALE;
-+		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
-+			err = vfs_unlink(upperdir->d_inode, realpath.dentry);
-+		if (err)
-+			goto out_d_drop;
-+
-+		ovl_dentry_version_inc(dentry->d_parent);
-+	}
-+
-+	if (type != OVL_PATH_UPPER || ovl_dentry_is_opaque(dentry))
-+		err = ovl_whiteout(upperdir, dentry);
-+
-+	/*
-+	 * Keeping this dentry hashed would mean having to release
-+	 * upperpath/lowerpath, which could only be done if we are the
-+	 * sole user of this dentry.  Too tricky...  Just unhash for
-+	 * now.
-+	 */
-+out_d_drop:
-+	d_drop(dentry);
-+	mutex_unlock(&upperdir->d_inode->i_mutex);
-+
-+	return err;
-+}
-+
-+static int ovl_unlink(struct inode *dir, struct dentry *dentry)
-+{
-+	return ovl_do_remove(dentry, false);
-+}
-+
-+
-+static int ovl_rmdir(struct inode *dir, struct dentry *dentry)
-+{
-+	int err;
-+	enum ovl_path_type type;
-+
-+	type = ovl_path_type(dentry);
-+	if (type != OVL_PATH_UPPER) {
-+		err = ovl_check_empty_and_clear(dentry, type);
-+		if (err)
-+			return err;
-+	}
-+
-+	return ovl_do_remove(dentry, true);
-+}
-+
-+static int ovl_link(struct dentry *old, struct inode *newdir,
-+		    struct dentry *new)
-+{
-+	int err;
-+	struct dentry *olddentry;
-+	struct dentry *newdentry;
-+	struct dentry *upperdir;
-+	struct inode *newinode;
-+
-+	err = ovl_copy_up(old);
-+	if (err)
-+		goto out;
-+
-+	err = ovl_copy_up(new->d_parent);
-+	if (err)
-+		goto out;
-+
-+	upperdir = ovl_dentry_upper(new->d_parent);
-+	mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT);
-+	newdentry = ovl_lookup_create(upperdir, new);
-+	err = PTR_ERR(newdentry);
-+	if (IS_ERR(newdentry))
-+		goto out_unlock;
-+
-+	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;
-+		}
-+		newinode = ovl_new_inode(old->d_sb, newdentry->d_inode->i_mode,
-+				new->d_fsdata);
-+		if (!newinode)
-+			goto link_fail;
-+		ovl_copyattr(upperdir->d_inode, newinode);
-+
-+		ovl_dentry_version_inc(new->d_parent);
-+		ovl_dentry_update(new, newdentry);
-+
-+		d_instantiate(new, newinode);
-+	} else {
-+link_fail:
-+		if (ovl_dentry_is_opaque(new))
-+			ovl_whiteout(upperdir, new);
-+		dput(newdentry);
-+	}
-+out_unlock:
-+	mutex_unlock(&upperdir->d_inode->i_mutex);
-+out:
-+	return err;
-+
-+}
-+
-+static int ovl_rename(struct inode *olddir, struct dentry *old,
-+			struct inode *newdir, struct dentry *new)
-+{
-+	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;
-+	struct dentry *newdentry;
-+	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 */
-+	old_type = ovl_path_type(old);
-+	if (old_type != OVL_PATH_UPPER && is_dir)
-+		return -EXDEV;
-+
-+	if (new->d_inode) {
-+		new_type = ovl_path_type(new);
-+
-+		if (new_type == OVL_PATH_LOWER && old_type == OVL_PATH_LOWER) {
-+			if (ovl_dentry_lower(old)->d_inode ==
-+			    ovl_dentry_lower(new)->d_inode)
-+				return 0;
-+		}
-+		if (new_type != OVL_PATH_LOWER && old_type != OVL_PATH_LOWER) {
-+			if (ovl_dentry_upper(old)->d_inode ==
-+			    ovl_dentry_upper(new)->d_inode)
-+				return 0;
-+		}
-+
-+		if (new_type != OVL_PATH_UPPER &&
-+		    S_ISDIR(new->d_inode->i_mode)) {
-+			err = ovl_check_empty_and_clear(new, new_type);
-+			if (err)
-+				return err;
-+		}
-+	} else {
-+		new_type = OVL_PATH_UPPER;
-+	}
-+
-+	err = ovl_copy_up(old);
-+	if (err)
-+		return err;
-+
-+	err = ovl_copy_up(new->d_parent);
-+	if (err)
-+		return err;
-+
-+	old_upperdir = ovl_dentry_upper(old->d_parent);
-+	new_upperdir = ovl_dentry_upper(new->d_parent);
-+
-+	trap = lock_rename(new_upperdir, old_upperdir);
-+
-+	olddentry = ovl_dentry_upper(old);
-+	newdentry = ovl_dentry_upper(new);
-+	if (newdentry) {
-+		dget(newdentry);
-+	} else {
-+		new_create = true;
-+		newdentry = ovl_lookup_create(new_upperdir, new);
-+		err = PTR_ERR(newdentry);
-+		if (IS_ERR(newdentry))
-+			goto out_unlock;
-+	}
-+
-+	err = -ESTALE;
-+	if (olddentry->d_parent != old_upperdir)
-+		goto out_dput;
-+	if (newdentry->d_parent != new_upperdir)
-+		goto out_dput;
-+	if (olddentry == trap)
-+		goto out_dput;
-+	if (newdentry == trap)
-+		goto out_dput;
-+
-+	old_opaque = ovl_dentry_is_opaque(old);
-+	new_opaque = ovl_dentry_is_opaque(new) || new_type != OVL_PATH_UPPER;
-+
-+	if (is_dir && !old_opaque && new_opaque) {
-+		err = ovl_set_opaque(olddentry);
-+		if (err)
-+			goto out_dput;
-+	}
-+
-+	err = vfs_rename(old_upperdir->d_inode, olddentry,
-+			 new_upperdir->d_inode, newdentry);
-+
-+	if (err) {
-+		if (new_create && ovl_dentry_is_opaque(new))
-+			ovl_whiteout(new_upperdir, new);
-+		if (is_dir && !old_opaque && new_opaque)
-+			ovl_remove_opaque(olddentry);
-+		goto out_dput;
-+	}
-+
-+	if (old_type != OVL_PATH_UPPER || old_opaque)
-+		err = ovl_whiteout(old_upperdir, old);
-+	if (is_dir && old_opaque && !new_opaque)
-+		ovl_remove_opaque(olddentry);
-+
-+	if (old_opaque != new_opaque)
-+		ovl_dentry_set_opaque(old, new_opaque);
-+
-+	ovl_dentry_version_inc(old->d_parent);
-+	ovl_dentry_version_inc(new->d_parent);
-+
-+out_dput:
-+	dput(newdentry);
-+out_unlock:
-+	unlock_rename(new_upperdir, old_upperdir);
-+	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 +1,372 @@
-+/*
-+ *
-+ * 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);
-+	if (!err)
-+		ovl_copyattr(upperdentry->d_inode, dentry->d_inode);
-+	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)
-+{
-+	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 (mask & MAY_NOT_BLOCK) {
-+		return -ECHILD;
-+	} else {
-+		/*
-+		 * For non-directories find an alias and get the info
-+		 * from there.
-+		 */
-+		alias = d_find_any_alias(inode);
-+		if (WARN_ON(!alias))
-+			return -ENOENT;
-+
-+		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(!(mask & MAY_NOT_BLOCK));
-+		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;
-+	}
-+
-+	err = __inode_permission(realinode, mask);
-+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);
-+
-+	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;
-+}
-+
-+int ovl_setxattr(struct dentry *dentry, const char *name,
-+		 const void *value, size_t size, int flags)
-+{
-+	int err;
-+	struct dentry *upperdentry;
-+
-+	if (ovl_is_private_xattr(name))
-+		return -EPERM;
-+
-+	err = ovl_copy_up(dentry);
-+	if (err)
-+		return err;
-+
-+	upperdentry = ovl_dentry_upper(dentry);
-+	return  vfs_setxattr(upperdentry, name, value, size, flags);
-+}
-+
-+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))
-+		return -ENODATA;
-+
-+	return vfs_getxattr(ovl_dentry_real(dentry), name, value, size);
-+}
-+
-+ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
-+{
-+	ssize_t res;
-+	int off;
-+
-+	res = vfs_listxattr(ovl_dentry_real(dentry), list, size);
-+	if (res <= 0 || size == 0)
-+		return res;
-+
-+	if (ovl_path_type(dentry->d_parent) != OVL_PATH_MERGE)
-+		return res;
-+
-+	/* filter out private xattrs */
-+	for (off = 0; off < res;) {
-+		char *s = list + off;
-+		size_t slen = strlen(s) + 1;
-+
-+		BUG_ON(off + slen > res);
-+
-+		if (ovl_is_private_xattr(s)) {
-+			res -= slen;
-+			memmove(s, s + slen, res - off);
-+		} else {
-+			off += slen;
-+		}
-+	}
-+
-+	return res;
-+}
-+
-+int ovl_removexattr(struct dentry *dentry, const char *name)
-+{
-+	int err;
-+	struct path realpath;
-+	enum ovl_path_type type;
-+
-+	if (ovl_path_type(dentry->d_parent) == OVL_PATH_MERGE &&
-+	    ovl_is_private_xattr(name))
-+		return -ENODATA;
-+
-+	type = ovl_path_real(dentry, &realpath);
-+	if (type == OVL_PATH_LOWER) {
-+		err = vfs_getxattr(realpath.dentry, name, NULL, 0);
-+		if (err < 0)
-+			return err;
-+
-+		err = ovl_copy_up(dentry);
-+		if (err)
-+			return err;
-+
-+		ovl_path_upper(dentry, &realpath);
-+	}
-+
-+	return vfs_removexattr(realpath.dentry, name);
-+}
-+
-+static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type,
-+				  struct dentry *realdentry)
-+{
-+	if (type != OVL_PATH_LOWER)
-+		return false;
-+
-+	if (special_file(realdentry->d_inode->i_mode))
-+		return false;
-+
-+	if (!(OPEN_FMODE(flags) & FMODE_WRITE) && !(flags & O_TRUNC))
-+		return false;
-+
-+	return true;
-+}
-+
-+static int ovl_dentry_open(struct dentry *dentry, struct file *file,
-+		    const struct cred *cred)
-+{
-+	int err;
-+	struct path realpath;
-+	enum ovl_path_type type;
-+
-+	type = ovl_path_real(dentry, &realpath);
-+	if (ovl_open_need_copy_up(file->f_flags, type, realpath.dentry)) {
-+		if (file->f_flags & O_TRUNC)
-+			err = ovl_copy_up_truncate(dentry, 0);
-+		else
-+			err = ovl_copy_up(dentry);
-+		if (err)
-+			return err;
-+
-+		ovl_path_upper(dentry, &realpath);
-+	}
-+
-+	return vfs_open(&realpath, file, cred);
-+}
-+
-+static const struct inode_operations ovl_file_inode_operations = {
-+	.setattr	= ovl_setattr,
-+	.permission	= ovl_permission,
-+	.getattr	= ovl_getattr,
-+	.setxattr	= ovl_setxattr,
-+	.getxattr	= ovl_getxattr,
-+	.listxattr	= ovl_listxattr,
-+	.removexattr	= ovl_removexattr,
-+	.dentry_open	= ovl_dentry_open,
-+};
-+
-+static const struct inode_operations ovl_symlink_inode_operations = {
-+	.setattr	= ovl_setattr,
-+	.follow_link	= ovl_follow_link,
-+	.put_link	= ovl_put_link,
-+	.readlink	= ovl_readlink,
-+	.getattr	= ovl_getattr,
-+	.setxattr	= ovl_setxattr,
-+	.getxattr	= ovl_getxattr,
-+	.listxattr	= ovl_listxattr,
-+	.removexattr	= ovl_removexattr,
-+};
-+
-+struct inode *ovl_new_inode(struct super_block *sb, umode_t mode,
-+			    struct ovl_entry *oe)
-+{
-+	struct inode *inode;
-+
-+	inode = new_inode(sb);
-+	if (!inode)
-+		return NULL;
-+
-+	mode &= S_IFMT;
-+
-+	inode->i_ino = get_next_ino();
-+	inode->i_mode = mode;
-+	inode->i_flags |= S_NOATIME | S_NOCMTIME;
-+
-+	switch (mode) {
-+	case S_IFDIR:
-+		inode->i_private = oe;
-+		inode->i_op = &ovl_dir_inode_operations;
-+		inode->i_fop = &ovl_dir_operations;
-+		break;
-+
-+	case S_IFLNK:
-+		inode->i_op = &ovl_symlink_inode_operations;
-+		break;
-+
-+	case S_IFREG:
-+	case S_IFSOCK:
-+	case S_IFBLK:
-+	case S_IFCHR:
-+	case S_IFIFO:
-+		inode->i_op = &ovl_file_inode_operations;
-+		break;
-+
-+	default:
-+		WARN(1, "illegal file type: %i\n", mode);
-+		iput(inode);
-+		inode = NULL;
-+	}
-+
-+	return inode;
-+
-+}
---- /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.
-+#
-+
-+obj-$(CONFIG_OVERLAYFS_FS) += overlayfs.o
-+
-+overlayfs-objs := super.o inode.o dir.o readdir.o copy_up.o
---- /dev/null
-+++ b/fs/overlayfs/overlayfs.h
-@@ -0,0 +1,70 @@
-+/*
-+ *
-+ * 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,
-+			  unsigned int flags);
-+struct file *ovl_path_open(struct path *path, int flags);
-+
-+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);
-+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);
-+static inline void ovl_copyattr(struct inode *from, struct inode *to)
-+{
-+	to->i_uid = from->i_uid;
-+	to->i_gid = from->i_gid;
-+}
-+
-+/* 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 +1,566 @@
-+/*
-+ *
-+ * 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 <linux/cred.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 = ovl_path_open(realpath, O_RDONLY | O_DIRECTORY);
-+	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, loff_t start, loff_t end,
-+			 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 = ovl_path_open(&upperpath, O_RDONLY);
-+		if (IS_ERR(od->realfile))
-+			return PTR_ERR(od->realfile);
-+	}
-+
-+	return vfs_fsync_range(od->realfile, start, end, 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 = ovl_path_open(&realpath, file->f_flags);
-+	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 +1,685 @@
-+/*
-+ *
-+ * 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/cred.h>
-+#include <linux/sched.h>
-+#include <linux/statfs.h>
-+#include <linux/seq_file.h>
-+#include "overlayfs.h"
-+
-+MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
-+MODULE_DESCRIPTION("Overlay filesystem");
-+MODULE_LICENSE("GPL");
-+
-+#define OVERLAYFS_SUPER_MAGIC 0x794c764f
-+
-+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;
-+	long lower_namelen;
-+	/* 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;
-+		ovl_copyattr(realdentry->d_inode, inode);
-+	}
-+
-+	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,
-+			  unsigned int flags)
-+{
-+	int err = ovl_do_lookup(dentry);
-+
-+	if (err)
-+		return ERR_PTR(err);
-+
-+	return NULL;
-+}
-+
-+struct file *ovl_path_open(struct path *path, int flags)
-+{
-+	path_get(path);
-+	return dentry_open(path, flags, current_cred());
-+}
-+
-+static void ovl_put_super(struct super_block *sb)
-+{
-+	struct ovl_fs *ufs = sb->s_fs_info;
-+
-+	if (!(sb->s_flags & MS_RDONLY))
-+		mnt_drop_write(ufs->upper_mnt);
-+
-+	mntput(ufs->upper_mnt);
-+	mntput(ufs->lower_mnt);
-+
-+	kfree(ufs->config.lowerdir);
-+	kfree(ufs->config.upperdir);
-+	kfree(ufs);
-+}
-+
-+static int ovl_remount_fs(struct super_block *sb, int *flagsp, char *data)
-+{
-+	int flags = *flagsp;
-+	struct ovl_fs *ufs = sb->s_fs_info;
-+
-+	/* When remounting rw or ro, we need to adjust the write access to the
-+	 * upper fs.
-+	 */
-+	if (((flags ^ sb->s_flags) & MS_RDONLY) == 0)
-+		/* No change to readonly status */
-+		return 0;
-+
-+	if (flags & MS_RDONLY) {
-+		mnt_drop_write(ufs->upper_mnt);
-+		return 0;
-+	} else
-+		return mnt_want_write(ufs->upper_mnt);
-+}
-+
-+/**
-+ * ovl_statfs
-+ * @sb: The overlayfs super block
-+ * @buf: The struct kstatfs to fill in with stats
-+ *
-+ * Get the filesystem statistics.  As writes always target the upper layer
-+ * filesystem pass the statfs to the same filesystem.
-+ */
-+static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
-+{
-+	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
-+	struct dentry *root_dentry = dentry->d_sb->s_root;
-+	struct path path;
-+	int err;
-+
-+	ovl_path_upper(root_dentry, &path);
-+
-+	err = vfs_statfs(&path, buf);
-+	if (!err) {
-+		buf->f_namelen = max(buf->f_namelen, ofs->lower_namelen);
-+		buf->f_type = OVERLAYFS_SUPER_MAGIC;
-+	}
-+
-+	return err;
-+}
-+
-+/**
-+ * 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 dentry *dentry)
-+{
-+	struct super_block *sb = dentry->d_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,
-+	.show_options	= ovl_show_options,
-+};
-+
-+enum {
-+	Opt_lowerdir,
-+	Opt_upperdir,
-+	Opt_err,
-+};
-+
-+static const match_table_t ovl_tokens = {
-+	{Opt_lowerdir,			"lowerdir=%s"},
-+	{Opt_upperdir,			"upperdir=%s"},
-+	{Opt_err,			NULL}
-+};
-+
-+static int ovl_parse_opt(char *opt, struct ovl_config *config)
-+{
-+	char *p;
-+
-+	config->upperdir = NULL;
-+	config->lowerdir = NULL;
-+
-+	while ((p = strsep(&opt, ",")) != NULL) {
-+		int token;
-+		substring_t args[MAX_OPT_ARGS];
-+
-+		if (!*p)
-+			continue;
-+
-+		token = match_token(p, ovl_tokens, args);
-+		switch (token) {
-+		case Opt_upperdir:
-+			kfree(config->upperdir);
-+			config->upperdir = match_strdup(&args[0]);
-+			if (!config->upperdir)
-+				return -ENOMEM;
-+			break;
-+
-+		case Opt_lowerdir:
-+			kfree(config->lowerdir);
-+			config->lowerdir = match_strdup(&args[0]);
-+			if (!config->lowerdir)
-+				return -ENOMEM;
-+			break;
-+
-+		default:
-+			return -EINVAL;
-+		}
-+	}
-+	return 0;
-+}
-+
-+static int ovl_fill_super(struct super_block *sb, void *data, int silent)
-+{
-+	struct path lowerpath;
-+	struct path upperpath;
-+	struct inode *root_inode;
-+	struct dentry *root_dentry;
-+	struct ovl_entry *oe;
-+	struct ovl_fs *ufs;
-+	struct kstatfs statfs;
-+	int 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 (!ufs->config.upperdir || !ufs->config.lowerdir) {
-+		printk(KERN_ERR "overlayfs: missing upperdir or lowerdir\n");
-+		goto out_free_config;
-+	}
-+
-+	oe = ovl_alloc_entry();
-+	if (oe == NULL)
-+		goto out_free_config;
-+
-+	err = kern_path(ufs->config.upperdir, LOOKUP_FOLLOW, &upperpath);
-+	if (err)
-+		goto out_free_oe;
-+
-+	err = kern_path(ufs->config.lowerdir, LOOKUP_FOLLOW, &lowerpath);
-+	if (err)
-+		goto out_put_upperpath;
-+
-+	err = -ENOTDIR;
-+	if (!S_ISDIR(upperpath.dentry->d_inode->i_mode) ||
-+	    !S_ISDIR(lowerpath.dentry->d_inode->i_mode))
-+		goto out_put_lowerpath;
-+
-+	err = vfs_statfs(&lowerpath, &statfs);
-+	if (err) {
-+		printk(KERN_ERR "overlayfs: statfs failed on lowerpath\n");
-+		goto out_put_lowerpath;
-+	}
-+	ufs->lower_namelen = statfs.f_namelen;
-+
-+	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)) {
-+		printk(KERN_ERR "overlayfs: failed to clone upperpath\n");
-+		goto out_put_lowerpath;
-+	}
-+
-+	ufs->lower_mnt = clone_private_mount(&lowerpath);
-+	err = PTR_ERR(ufs->lower_mnt);
-+	if (IS_ERR(ufs->lower_mnt)) {
-+		printk(KERN_ERR "overlayfs: failed to clone lowerpath\n");
-+		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)
-+			goto out_put_lower_mnt;
-+	}
-+
-+	err = -ENOMEM;
-+	root_inode = ovl_new_inode(sb, S_IFDIR, oe);
-+	if (!root_inode)
-+		goto out_drop_write;
-+
-+	root_dentry = d_make_root(root_inode);
-+	if (!root_dentry)
-+		goto out_drop_write;
-+
-+	mntput(upperpath.mnt);
-+	mntput(lowerpath.mnt);
-+
-+	oe->__upperdentry = dget(upperpath.dentry);
-+	oe->lowerdentry = lowerpath.dentry;
-+
-+	root_dentry->d_fsdata = oe;
-+	root_dentry->d_op = &ovl_dentry_operations;
-+
-+	sb->s_magic = OVERLAYFS_SUPER_MAGIC;
-+	sb->s_op = &ovl_super_operations;
-+	sb->s_root = root_dentry;
-+	sb->s_fs_info = ufs;
-+
-+	return 0;
-+
-+out_drop_write:
-+	if (!(sb->s_flags & MS_RDONLY))
-+		mnt_drop_write(ufs->upper_mnt);
-+out_put_lower_mnt:
-+	mntput(ufs->lower_mnt);
-+out_put_upper_mnt:
-+	mntput(ufs->upper_mnt);
-+out_put_lowerpath:
-+	path_put(&lowerpath);
-+out_put_upperpath:
-+	path_put(&upperpath);
-+out_free_oe:
-+	kfree(oe);
-+out_free_config:
-+	kfree(ufs->config.lowerdir);
-+	kfree(ufs->config.upperdir);
-+out_free_ufs:
-+	kfree(ufs);
-+out:
-+	return err;
-+}
-+
-+static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags,
-+				const char *dev_name, void *raw_data)
-+{
-+	return mount_nodev(fs_type, flags, raw_data, ovl_fill_super);
-+}
-+
-+static struct file_system_type ovl_fs_type = {
-+	.owner		= THIS_MODULE,
-+	.name		= "overlayfs",
-+	.mount		= ovl_mount,
-+	.kill_sb	= kill_anon_super,
-+};
-+
-+static int __init ovl_init(void)
-+{
-+	return register_filesystem(&ovl_fs_type);
-+}
-+
-+static void __exit ovl_exit(void)
-+{
-+	unregister_filesystem(&ovl_fs_type);
-+}
-+
-+module_init(ovl_init);
-+module_exit(ovl_exit);
---- a/fs/splice.c
-+++ b/fs/splice.c
-@@ -1307,6 +1307,7 @@ 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
-@@ -244,6 +244,12 @@ 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
-+
- /** 
-  * enum positive_aop_returns - aop return codes with specific semantics
-  *
-@@ -1320,6 +1326,11 @@ struct super_block {
- 
- 	/* Being remounted read-only */
- 	int s_readonly_remount;
-+
-+	/*
-+	 * Indicates how deep in a filesystem stack this SB is
-+	 */
-+	int s_stack_depth;
- };
- 
- /* superblock cache pruning functions */
-@@ -1573,6 +1584,7 @@ struct inode_operations {
- 	int (*atomic_open)(struct inode *, struct dentry *,
- 			   struct file *, unsigned open_flag,
- 			   umode_t create_mode, int *opened);
-+	int (*dentry_open)(struct dentry *, struct file *, const struct cred *);
- } ____cacheline_aligned;
- 
- ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
-@@ -2005,6 +2017,7 @@ extern struct file *file_open_name(struc
- extern struct file *filp_open(const char *, int, umode_t);
- extern struct file *file_open_root(struct dentry *, struct vfsmount *,
- 				   const char *, int);
-+extern int vfs_open(const struct path *, struct file *, const struct cred *);
- extern struct file * dentry_open(const struct path *, int, const struct cred *);
- extern int filp_close(struct file *, fl_owner_t id);
- 
-@@ -2210,6 +2223,7 @@ extern sector_t bmap(struct inode *, sec
- #endif
- extern int notify_change(struct dentry *, struct iattr *);
- extern int inode_permission(struct inode *, int);
-+extern int __inode_permission(struct inode *, int);
- extern int generic_permission(struct inode *, int);
- 
- static inline bool execute_ok(struct inode *inode)
---- a/include/linux/mount.h
-+++ b/include/linux/mount.h
-@@ -68,6 +68,9 @@ 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);
-+
- struct file_system_type;
- extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
- 				      int flags, const char *name,
---- a/MAINTAINERS
-+++ b/MAINTAINERS
-@@ -5666,6 +5666,13 @@ 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