1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3  *
4  * Copyright (C) 2011 Novell Inc.
5  * Copyright (C) 2016 Red Hat, Inc.
6  */
7 
8 struct ovl_config {
9 	char *lowerdir;
10 	char *upperdir;
11 	char *workdir;
12 	bool default_permissions;
13 	bool redirect_dir;
14 	bool redirect_follow;
15 	const char *redirect_mode;
16 	bool index;
17 	bool uuid;
18 	bool nfs_export;
19 	int xino;
20 	bool metacopy;
21 	bool userxattr;
22 	bool ovl_volatile;
23 };
24 
25 struct ovl_sb {
26 	struct super_block *sb;
27 	dev_t pseudo_dev;
28 	/* Unusable (conflicting) uuid */
29 	bool bad_uuid;
30 	/* Used as a lower layer (but maybe also as upper) */
31 	bool is_lower;
32 };
33 
34 struct ovl_layer {
35 	struct vfsmount *mnt;
36 	/* Trap in ovl inode cache */
37 	struct inode *trap;
38 	struct ovl_sb *fs;
39 	/* Index of this layer in fs root (upper idx == 0) */
40 	int idx;
41 	/* One fsid per unique underlying sb (upper fsid == 0) */
42 	int fsid;
43 };
44 
45 struct ovl_path {
46 	const struct ovl_layer *layer;
47 	struct dentry *dentry;
48 };
49 
50 /* private information held for overlayfs's superblock */
51 struct ovl_fs {
52 	unsigned int numlayer;
53 	/* Number of unique fs among layers including upper fs */
54 	unsigned int numfs;
55 	const struct ovl_layer *layers;
56 	struct ovl_sb *fs;
57 	/* workbasedir is the path at workdir= mount option */
58 	struct dentry *workbasedir;
59 	/* workdir is the 'work' directory under workbasedir */
60 	struct dentry *workdir;
61 	/* index directory listing overlay inodes by origin file handle */
62 	struct dentry *indexdir;
63 	long namelen;
64 	/* pathnames of lower and upper dirs, for show_options */
65 	struct ovl_config config;
66 	/* creds of process who forced instantiation of super block */
67 	const struct cred *creator_cred;
68 	bool tmpfile;
69 	bool noxattr;
70 	/* Did we take the inuse lock? */
71 	bool upperdir_locked;
72 	bool workdir_locked;
73 	bool share_whiteout;
74 	/* Traps in ovl inode cache */
75 	struct inode *workbasedir_trap;
76 	struct inode *workdir_trap;
77 	struct inode *indexdir_trap;
78 	/* -1: disabled, 0: same fs, 1..32: number of unused ino bits */
79 	int xino_mode;
80 	/* For allocation of non-persistent inode numbers */
81 	atomic_long_t last_ino;
82 	/* Whiteout dentry cache */
83 	struct dentry *whiteout;
84 	/* r/o snapshot of upperdir sb's only taken on volatile mounts */
85 	errseq_t errseq;
86 };
87 
ovl_upper_mnt(struct ovl_fs * ofs)88 static inline struct vfsmount *ovl_upper_mnt(struct ovl_fs *ofs)
89 {
90 	return ofs->layers[0].mnt;
91 }
92 
ovl_upper_mnt_userns(struct ovl_fs * ofs)93 static inline struct user_namespace *ovl_upper_mnt_userns(struct ovl_fs *ofs)
94 {
95 	return mnt_user_ns(ovl_upper_mnt(ofs));
96 }
97 
OVL_FS(struct super_block * sb)98 static inline struct ovl_fs *OVL_FS(struct super_block *sb)
99 {
100 	return (struct ovl_fs *)sb->s_fs_info;
101 }
102 
ovl_should_sync(struct ovl_fs * ofs)103 static inline bool ovl_should_sync(struct ovl_fs *ofs)
104 {
105 	return !ofs->config.ovl_volatile;
106 }
107 
108 /* private information held for every overlayfs dentry */
109 struct ovl_entry {
110 	union {
111 		struct {
112 			unsigned long flags;
113 		};
114 		struct rcu_head rcu;
115 	};
116 	unsigned numlower;
117 	struct ovl_path lowerstack[];
118 };
119 
120 struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
121 
OVL_E(struct dentry * dentry)122 static inline struct ovl_entry *OVL_E(struct dentry *dentry)
123 {
124 	return (struct ovl_entry *) dentry->d_fsdata;
125 }
126 
127 struct ovl_inode {
128 	union {
129 		struct ovl_dir_cache *cache;	/* directory */
130 		struct inode *lowerdata;	/* regular file */
131 	};
132 	const char *redirect;
133 	u64 version;
134 	unsigned long flags;
135 	struct inode vfs_inode;
136 	struct dentry *__upperdentry;
137 	struct ovl_path lowerpath;
138 
139 	/* synchronize copy up and more */
140 	struct mutex lock;
141 };
142 
OVL_I(struct inode * inode)143 static inline struct ovl_inode *OVL_I(struct inode *inode)
144 {
145 	return container_of(inode, struct ovl_inode, vfs_inode);
146 }
147 
ovl_upperdentry_dereference(struct ovl_inode * oi)148 static inline struct dentry *ovl_upperdentry_dereference(struct ovl_inode *oi)
149 {
150 	return READ_ONCE(oi->__upperdentry);
151 }
152