+++ /dev/null
---- a/Documentation/filesystems/Locking
-+++ b/Documentation/filesystems/Locking
-@@ -65,6 +65,7 @@ prototypes:
- struct file *, unsigned open_flag,
- umode_t create_mode, int *opened);
- int (*tmpfile) (struct inode *, struct dentry *, umode_t);
-+ int (*dentry_open)(struct dentry *, struct file *, const struct cred *);
-
- locking rules:
- all may block
-@@ -93,6 +94,7 @@ fiemap: no
- update_time: no
- atomic_open: yes
- tmpfile: no
-+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 (*tmpfile) (struct inode *, struct dentry *, umode_t);
-+ 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/MAINTAINERS
-+++ b/MAINTAINERS
-@@ -6245,6 +6245,13 @@ 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
-@@ -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
-@@ -105,6 +105,7 @@ 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/ecryptfs/main.c
-+++ b/fs/ecryptfs/main.c
-@@ -566,6 +566,13 @@ 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) {
-+ pr_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
-@@ -44,7 +44,6 @@ extern void __init chrdev_init(void);
- /*
- * namei.c
- */
--extern int __inode_permission(struct inode *, int);
- extern int user_path_mountpoint_at(int, const char __user *, unsigned int, struct path *);
- extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
- const char *, unsigned int, struct path *);
-@@ -142,12 +141,6 @@ extern ssize_t __kernel_write(struct fil
- extern int rw_verify_area(int, struct file *, const loff_t *, size_t);
-
- /*
-- * splice.c
-- */
--extern long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
-- loff_t *opos, size_t len, unsigned int flags);
--
--/*
- * pipe.c
- */
- extern const struct file_operations pipefifo_fops;
---- 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
-@@ -3065,9 +3066,12 @@ 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
-@@ -1466,6 +1466,33 @@ void drop_collected_mounts(struct vfsmou
- namespace_unlock();
- }
-
-+/**
-+ * clone_private_mount - create a private clone of a path
-+ *
-+ * This creates a new vfsmount, which will be the clone of @path. The new will
-+ * not be attached anywhere in the namespace and will be private (i.e. changes
-+ * to the originating mount won't be propagated into this).
-+ *
-+ * Release with mntput().
-+ */
-+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 (IS_ERR(new_mnt))
-+ return ERR_CAST(new_mnt);
-+
-+ 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
-@@ -814,8 +814,7 @@ struct file *dentry_open(const struct pa
- f = get_empty_filp();
- if (!IS_ERR(f)) {
- f->f_flags = flags;
-- f->f_path = *path;
-- error = do_dentry_open(f, NULL, cred);
-+ error = vfs_open(path, f, cred);
- if (!error) {
- /* from now on we need fput() to dispose of f */
- error = open_check_o_direct(f);
-@@ -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/Kconfig
-@@ -0,0 +1,10 @@
-+config OVERLAYFS_FS
-+ tristate "Overlay filesystem support"
-+ help
-+ 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.
-+
-+ For more information see Documentation/filesystems/overlayfs.txt
---- /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/copy_up.c
-@@ -0,0 +1,388 @@
-+/*
-+ *
-+ * 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;
-+ loff_t old_pos = 0;
-+ loff_t new_pos = 0;
-+ 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) {
-+ 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, &old_pos,
-+ new_file, &new_pos,
-+ this_len, SPLICE_F_MOVE);
-+ if (bytes <= 0) {
-+ error = bytes;
-+ break;
-+ }
-+ WARN_ON(old_pos != new_pos);
-+
-+ 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, &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, &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, &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 +1,605 @@
-+/*
-+ *
-+ * 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... ?
-+ */
-+ pr_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, 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) {
-+ err = -ENOMEM;
-+ 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, 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/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 +1,567 @@
-+/*
-+ *
-+ * 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 dir_context ctx;
-+ bool is_merge;
-+ 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(struct ovl_readdir_data *rdd,
-+ const char *name, int namelen,
-+ loff_t offset, u64 ino, unsigned int d_type)
-+{
-+ struct ovl_cache_entry *p;
-+
-+ 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_merge(void *buf, const char *name, int namelen,
-+ loff_t offset, u64 ino, unsigned int d_type)
-+{
-+ struct ovl_readdir_data *rdd = buf;
-+
-+ rdd->count++;
-+ if (!rdd->is_merge)
-+ return ovl_cache_entry_add_rb(rdd, name, namelen, ino, d_type);
-+ else
-+ return ovl_fill_lower(rdd, name, namelen, offset, ino, d_type);
-+}
-+
-+static inline int ovl_dir_read(struct path *realpath,
-+ struct ovl_readdir_data *rdd)
-+{
-+ struct file *realfile;
-+ int err;
-+
-+ realfile = ovl_path_open(realpath, O_RDONLY | O_DIRECTORY);
-+ if (IS_ERR(realfile))
-+ return PTR_ERR(realfile);
-+
-+ rdd->ctx.pos = 0;
-+ do {
-+ rdd->count = 0;
-+ rdd->err = 0;
-+ err = iterate_dir(realfile, &rdd->ctx);
-+ 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 list_head *list)
-+{
-+ int err;
-+ struct rb_root root = RB_ROOT;
-+ struct list_head middle;
-+ struct ovl_readdir_data rdd = {
-+ .ctx.actor = ovl_fill_merge,
-+ .list = list,
-+ .root = &root,
-+ .is_merge = false,
-+ };
-+
-+ if (upperpath->dentry) {
-+ rdd.dir = upperpath->dentry;
-+ err = ovl_dir_read(upperpath, &rdd);
-+ 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;
-+ rdd.is_merge = true;
-+ err = ovl_dir_read(lowerpath, &rdd);
-+ list_del(&middle);
-+out:
-+ 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_iterate(struct file *file, struct dir_context *ctx)
-+{
-+ struct ovl_dir_file *od = file->private_data;
-+ int res;
-+
-+ if (!ctx->pos)
-+ ovl_dir_reset(file);
-+
-+ if (od->is_real) {
-+ res = iterate_dir(od->realfile, ctx);
-+
-+ return res;
-+ }
-+
-+ if (!od->is_cached) {
-+ struct path lowerpath;
-+ struct path upperpath;
-+
-+ ovl_path_lower(file->f_path.dentry, &lowerpath);
-+ ovl_path_upper(file->f_path.dentry, &upperpath);
-+
-+ res = ovl_dir_read_merged(&upperpath, &lowerpath, &od->cache);
-+ if (res) {
-+ ovl_cache_free(&od->cache);
-+ return res;
-+ }
-+
-+ od->cache_version = ovl_dentry_version_get(file->f_path.dentry);
-+ od->is_cached = true;
-+
-+ ovl_seek_cursor(od, ctx->pos);
-+ }
-+
-+ while (od->cursor.next != &od->cache) {
-+ struct ovl_cache_entry *p;
-+
-+ p = list_entry(od->cursor.next, struct ovl_cache_entry, l_node);
-+ if (!p->is_whiteout) {
-+ if (!dir_emit(ctx, p->name, p->len, p->ino, p->type))
-+ break;
-+ }
-+ ctx->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_inode(file)->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_inode(file)->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,
-+ .iterate = ovl_iterate,
-+ .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;
-+
-+ ovl_path_upper(dentry, &upperpath);
-+ ovl_path_lower(dentry, &lowerpath);
-+
-+ err = ovl_dir_read_merged(&upperpath, &lowerpath, list);
-+ 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)) {
-+ pr_warn(
-+ "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)
-+ pr_warn(
-+ "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)
-+{
-+ 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) {
-+ pr_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) {
-+ pr_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) {
-+ pr_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)) {
-+ pr_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)) {
-+ pr_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,
-+};
-+MODULE_ALIAS_FS("overlayfs");
-+
-+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
-@@ -1309,6 +1309,7 @@ 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
-@@ -246,6 +246,12 @@ 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
- *
-@@ -1330,6 +1336,11 @@ struct super_block {
- */
- struct list_lru s_dentry_lru ____cacheline_aligned_in_smp;
- struct list_lru s_inode_lru ____cacheline_aligned_in_smp;
-+
-+ /*
-+ * Indicates how deep in a filesystem stack this SB is
-+ */
-+ int s_stack_depth;
- };
-
- extern struct timespec current_fs_time(struct super_block *sb);
-@@ -1585,6 +1596,7 @@ struct inode_operations {
- struct file *, unsigned open_flag,
- umode_t create_mode, int *opened);
- int (*tmpfile) (struct inode *, struct dentry *, umode_t);
-+ 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,
-@@ -2019,6 +2031,7 @@ 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);
-
-@@ -2225,6 +2238,7 @@ 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)
-@@ -2430,6 +2444,9 @@ extern ssize_t generic_file_splice_write
- struct file *, loff_t *, size_t, unsigned int);
- extern ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe,
- struct file *out, loff_t *, size_t len, unsigned int flags);
-+extern long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
-+ loff_t *opos, size_t len, unsigned int flags);
-+
-
- extern void
- file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping);
---- a/include/linux/mount.h
-+++ b/include/linux/mount.h
-@@ -69,6 +69,9 @@ 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,
projects / openwrt.git / blobdiff