xref: /openbmc/linux/fs/overlayfs/ovl_entry.h (revision a34a3ed7)
1 /*
2  *
3  * Copyright (C) 2011 Novell Inc.
4  * Copyright (C) 2016 Red Hat, Inc.
5  *
6  * This program is free software; you can redistribute it and/or modify it
7  * under the terms of the GNU General Public License version 2 as published by
8  * the Free Software Foundation.
9  */
10 
11 struct ovl_config {
12 	char *lowerdir;
13 	char *upperdir;
14 	char *workdir;
15 	bool default_permissions;
16 	bool redirect_dir;
17 	bool redirect_follow;
18 	const char *redirect_mode;
19 	bool index;
20 	bool nfs_export;
21 };
22 
23 struct ovl_layer {
24 	struct vfsmount *mnt;
25 	dev_t pseudo_dev;
26 	/* Index of this layer in fs root (upper == 0) */
27 	int idx;
28 };
29 
30 struct ovl_path {
31 	struct ovl_layer *layer;
32 	struct dentry *dentry;
33 };
34 
35 /* private information held for overlayfs's superblock */
36 struct ovl_fs {
37 	struct vfsmount *upper_mnt;
38 	unsigned numlower;
39 	struct ovl_layer *lower_layers;
40 	/* workbasedir is the path at workdir= mount option */
41 	struct dentry *workbasedir;
42 	/* workdir is the 'work' directory under workbasedir */
43 	struct dentry *workdir;
44 	/* index directory listing overlay inodes by origin file handle */
45 	struct dentry *indexdir;
46 	long namelen;
47 	/* pathnames of lower and upper dirs, for show_options */
48 	struct ovl_config config;
49 	/* creds of process who forced instantiation of super block */
50 	const struct cred *creator_cred;
51 	bool tmpfile;
52 	bool noxattr;
53 	/* sb common to all layers */
54 	struct super_block *same_sb;
55 	/* Did we take the inuse lock? */
56 	bool upperdir_locked;
57 	bool workdir_locked;
58 };
59 
60 /* private information held for every overlayfs dentry */
61 struct ovl_entry {
62 	union {
63 		struct {
64 			unsigned long flags;
65 		};
66 		struct rcu_head rcu;
67 	};
68 	unsigned numlower;
69 	struct ovl_path lowerstack[];
70 };
71 
72 struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
73 
74 static inline struct ovl_entry *OVL_E(struct dentry *dentry)
75 {
76 	return (struct ovl_entry *) dentry->d_fsdata;
77 }
78 
79 struct ovl_inode {
80 	struct ovl_dir_cache *cache;
81 	const char *redirect;
82 	u64 version;
83 	unsigned long flags;
84 	struct inode vfs_inode;
85 	struct dentry *__upperdentry;
86 	struct inode *lower;
87 
88 	/* synchronize copy up and more */
89 	struct mutex lock;
90 };
91 
92 static inline struct ovl_inode *OVL_I(struct inode *inode)
93 {
94 	return container_of(inode, struct ovl_inode, vfs_inode);
95 }
96 
97 static inline struct dentry *ovl_upperdentry_dereference(struct ovl_inode *oi)
98 {
99 	return READ_ONCE(oi->__upperdentry);
100 }
101