2cac0c00a6
Bad things can happen if several concurrent overlay mounts try to use the same upperdir/workdir path. Try to get the 'inuse' advisory lock on upperdir and workdir. Fail mount if another overlay mount instance or another user holds the 'inuse' lock on these directories. Note that this provides no protection for concurrent overlay mount that use overlapping (i.e. descendant) upper/work dirs. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
73 lines
1.7 KiB
C
73 lines
1.7 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;
|
|
/* workbasedir is the path at workdir= mount option */
|
|
struct dentry *workbasedir;
|
|
/* workdir is the 'work' directory under workbasedir */
|
|
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;
|
|
bool tmpfile;
|
|
bool noxattr;
|
|
/* sb common to all layers */
|
|
struct super_block *same_sb;
|
|
};
|
|
|
|
/* private information held for every overlayfs dentry */
|
|
struct ovl_entry {
|
|
union {
|
|
bool opaque;
|
|
struct rcu_head rcu;
|
|
};
|
|
unsigned numlower;
|
|
struct path lowerstack[];
|
|
};
|
|
|
|
struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
|
|
|
|
struct ovl_inode {
|
|
struct ovl_dir_cache *cache;
|
|
const char *redirect;
|
|
u64 version;
|
|
unsigned long flags;
|
|
struct inode vfs_inode;
|
|
struct dentry *__upperdentry;
|
|
struct inode *lower;
|
|
|
|
/* synchronize copy up and more */
|
|
struct mutex lock;
|
|
};
|
|
|
|
static inline struct ovl_inode *OVL_I(struct inode *inode)
|
|
{
|
|
return container_of(inode, struct ovl_inode, vfs_inode);
|
|
}
|
|
|
|
static inline struct dentry *ovl_upperdentry_dereference(struct ovl_inode *oi)
|
|
{
|
|
return lockless_dereference(oi->__upperdentry);
|
|
}
|