linux/fs/overlayfs/ovl_entry.h
Miklos Szeredi a6c6065511 ovl: redirect on rename-dir
Current code returns EXDEV when a directory would need to be copied up to
move.  We could copy up the directory tree in this case, but there's
another, simpler solution: point to old lower directory from moved upper
directory.

This is achieved with a "trusted.overlay.redirect" xattr storing the path
relative to the root of the overlay.  After such attribute has been set,
the directory can be moved without further actions required.

This is a backward incompatible feature, old kernels won't be able to
correctly mount an overlay containing redirected directories.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-12-16 11:02:56 +01:00

54 lines
1.2 KiB
C

/*
*
* Copyright (C) 2011 Novell Inc.
* Copyright (C) 2016 Red Hat, 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_config {
char *lowerdir;
char *upperdir;
char *workdir;
bool default_permissions;
bool redirect_dir;
};
/* private information held for overlayfs's superblock */
struct ovl_fs {
struct vfsmount *upper_mnt;
unsigned numlower;
struct vfsmount **lower_mnt;
struct dentry *workdir;
long namelen;
/* pathnames of lower and upper dirs, for show_options */
struct ovl_config config;
/* creds of process who forced instantiation of super block */
const struct cred *creator_cred;
};
/* private information held for every overlayfs dentry */
struct ovl_entry {
struct dentry *__upperdentry;
struct ovl_dir_cache *cache;
union {
struct {
u64 version;
const char *redirect;
bool opaque;
};
struct rcu_head rcu;
};
unsigned numlower;
struct path lowerstack[];
};
struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
static inline struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe)
{
return lockless_dereference(oe->__upperdentry);
}