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
8struct ovl_config {
9	char *upperdir;
10	char *workdir;
11	char **lowerdirs;
12	bool default_permissions;
13	int redirect_mode;
14	int verity_mode;
15	bool index;
16	int uuid;
17	bool nfs_export;
18	int xino;
19	bool metacopy;
20	bool userxattr;
21	bool ovl_volatile;
22};
23
24struct ovl_sb {
25	struct super_block *sb;
26	dev_t pseudo_dev;
27	/* Unusable (conflicting) uuid */
28	bool bad_uuid;
29	/* Used as a lower layer (but maybe also as upper) */
30	bool is_lower;
31};
32
33struct ovl_layer {
34	/* ovl_free_fs() relies on @mnt being the first member! */
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	/* xwhiteouts were found on this layer */
44	bool has_xwhiteouts;
45};
46
47struct ovl_path {
48	const struct ovl_layer *layer;
49	struct dentry *dentry;
50};
51
52struct ovl_entry {
53	unsigned int __numlower;
54	struct ovl_path __lowerstack[];
55};
56
57/* private information held for overlayfs's superblock */
58struct ovl_fs {
59	unsigned int numlayer;
60	/* Number of unique fs among layers including upper fs */
61	unsigned int numfs;
62	/* Number of data-only lower layers */
63	unsigned int numdatalayer;
64	struct ovl_layer *layers;
65	struct ovl_sb *fs;
66	/* workbasedir is the path at workdir= mount option */
67	struct dentry *workbasedir;
68	/* workdir is the 'work' or 'index' directory under workbasedir */
69	struct dentry *workdir;
70	long namelen;
71	/* pathnames of lower and upper dirs, for show_options */
72	struct ovl_config config;
73	/* creds of process who forced instantiation of super block */
74	const struct cred *creator_cred;
75	bool tmpfile;
76	bool noxattr;
77	bool nofh;
78	/* Did we take the inuse lock? */
79	bool upperdir_locked;
80	bool workdir_locked;
81	/* Traps in ovl inode cache */
82	struct inode *workbasedir_trap;
83	struct inode *workdir_trap;
84	/* -1: disabled, 0: same fs, 1..32: number of unused ino bits */
85	int xino_mode;
86	/* For allocation of non-persistent inode numbers */
87	atomic_long_t last_ino;
88	/* Shared whiteout cache */
89	struct dentry *whiteout;
90	bool no_shared_whiteout;
91	/* r/o snapshot of upperdir sb's only taken on volatile mounts */
92	errseq_t errseq;
93};
94
95/* Number of lower layers, not including data-only layers */
96static inline unsigned int ovl_numlowerlayer(struct ovl_fs *ofs)
97{
98	return ofs->numlayer - ofs->numdatalayer - 1;
99}
100
101static inline struct vfsmount *ovl_upper_mnt(struct ovl_fs *ofs)
102{
103	return ofs->layers[0].mnt;
104}
105
106static inline struct mnt_idmap *ovl_upper_mnt_idmap(struct ovl_fs *ofs)
107{
108	return mnt_idmap(ovl_upper_mnt(ofs));
109}
110
111extern struct file_system_type ovl_fs_type;
112
113static inline struct ovl_fs *OVL_FS(struct super_block *sb)
114{
115	if (IS_ENABLED(CONFIG_OVERLAY_FS_DEBUG))
116		WARN_ON_ONCE(sb->s_type != &ovl_fs_type);
117
118	return (struct ovl_fs *)sb->s_fs_info;
119}
120
121static inline bool ovl_should_sync(struct ovl_fs *ofs)
122{
123	return !ofs->config.ovl_volatile;
124}
125
126static inline unsigned int ovl_numlower(struct ovl_entry *oe)
127{
128	return oe ? oe->__numlower : 0;
129}
130
131static inline struct ovl_path *ovl_lowerstack(struct ovl_entry *oe)
132{
133	return ovl_numlower(oe) ? oe->__lowerstack : NULL;
134}
135
136static inline struct ovl_path *ovl_lowerpath(struct ovl_entry *oe)
137{
138	return ovl_lowerstack(oe);
139}
140
141static inline struct ovl_path *ovl_lowerdata(struct ovl_entry *oe)
142{
143	struct ovl_path *lowerstack = ovl_lowerstack(oe);
144
145	return lowerstack ? &lowerstack[oe->__numlower - 1] : NULL;
146}
147
148/* May return NULL if lazy lookup of lowerdata is needed */
149static inline struct dentry *ovl_lowerdata_dentry(struct ovl_entry *oe)
150{
151	struct ovl_path *lowerdata = ovl_lowerdata(oe);
152
153	return lowerdata ? READ_ONCE(lowerdata->dentry) : NULL;
154}
155
156/* private information held for every overlayfs dentry */
157static inline unsigned long *OVL_E_FLAGS(struct dentry *dentry)
158{
159	return (unsigned long *) &dentry->d_fsdata;
160}
161
162struct ovl_inode {
163	union {
164		struct ovl_dir_cache *cache;	/* directory */
165		const char *lowerdata_redirect;	/* regular file */
166	};
167	const char *redirect;
168	u64 version;
169	unsigned long flags;
170	struct inode vfs_inode;
171	struct dentry *__upperdentry;
172	struct ovl_entry *oe;
173
174	/* synchronize copy up and more */
175	struct mutex lock;
176};
177
178static inline struct ovl_inode *OVL_I(struct inode *inode)
179{
180	return container_of(inode, struct ovl_inode, vfs_inode);
181}
182
183static inline struct ovl_entry *OVL_I_E(struct inode *inode)
184{
185	return inode ? OVL_I(inode)->oe : NULL;
186}
187
188static inline struct ovl_entry *OVL_E(struct dentry *dentry)
189{
190	return OVL_I_E(d_inode(dentry));
191}
192
193static inline struct dentry *ovl_upperdentry_dereference(struct ovl_inode *oi)
194{
195	return READ_ONCE(oi->__upperdentry);
196}
197