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};
44
45struct ovl_path {
46 const struct ovl_layer *layer;
47 struct dentry *dentry;
48};
49
50struct ovl_entry {
51 unsigned int __numlower;
52 struct ovl_path __lowerstack[];
53};
54
55/* private information held for overlayfs's superblock */
56struct ovl_fs {
57 unsigned int numlayer;
58 /* Number of unique fs among layers including upper fs */
59 unsigned int numfs;
60 /* Number of data-only lower layers */
61 unsigned int numdatalayer;
62 const struct ovl_layer *layers;
63 struct ovl_sb *fs;
64 /* workbasedir is the path at workdir= mount option */
65 struct dentry *workbasedir;
66 /* workdir is the 'work' directory under workbasedir */
67 struct dentry *workdir;
68 /* index directory listing overlay inodes by origin file handle */
69 struct dentry *indexdir;
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 struct inode *indexdir_trap;
85 /* -1: disabled, 0: same fs, 1..32: number of unused ino bits */
86 int xino_mode;
87 /* For allocation of non-persistent inode numbers */
88 atomic_long_t last_ino;
89 /* Shared whiteout cache */
90 struct dentry *whiteout;
91 bool no_shared_whiteout;
92 /* r/o snapshot of upperdir sb's only taken on volatile mounts */
93 errseq_t errseq;
94};
95
96/* Number of lower layers, not including data-only layers */
97static inline unsigned int ovl_numlowerlayer(struct ovl_fs *ofs)
98{
99 return ofs->numlayer - ofs->numdatalayer - 1;
100}
101
102static inline struct vfsmount *ovl_upper_mnt(struct ovl_fs *ofs)
103{
104 return ofs->layers[0].mnt;
105}
106
107static inline struct mnt_idmap *ovl_upper_mnt_idmap(struct ovl_fs *ofs)
108{
109 return mnt_idmap(mnt: ovl_upper_mnt(ofs));
110}
111
112extern struct file_system_type ovl_fs_type;
113
114static inline struct ovl_fs *OVL_FS(struct super_block *sb)
115{
116 if (IS_ENABLED(CONFIG_OVERLAY_FS_DEBUG))
117 WARN_ON_ONCE(sb->s_type != &ovl_fs_type);
118
119 return (struct ovl_fs *)sb->s_fs_info;
120}
121
122static inline bool ovl_should_sync(struct ovl_fs *ofs)
123{
124 return !ofs->config.ovl_volatile;
125}
126
127static inline unsigned int ovl_numlower(struct ovl_entry *oe)
128{
129 return oe ? oe->__numlower : 0;
130}
131
132static inline struct ovl_path *ovl_lowerstack(struct ovl_entry *oe)
133{
134 return ovl_numlower(oe) ? oe->__lowerstack : NULL;
135}
136
137static inline struct ovl_path *ovl_lowerpath(struct ovl_entry *oe)
138{
139 return ovl_lowerstack(oe);
140}
141
142static inline struct ovl_path *ovl_lowerdata(struct ovl_entry *oe)
143{
144 struct ovl_path *lowerstack = ovl_lowerstack(oe);
145
146 return lowerstack ? &lowerstack[oe->__numlower - 1] : NULL;
147}
148
149/* May return NULL if lazy lookup of lowerdata is needed */
150static inline struct dentry *ovl_lowerdata_dentry(struct ovl_entry *oe)
151{
152 struct ovl_path *lowerdata = ovl_lowerdata(oe);
153
154 return lowerdata ? READ_ONCE(lowerdata->dentry) : NULL;
155}
156
157/* private information held for every overlayfs dentry */
158static inline unsigned long *OVL_E_FLAGS(struct dentry *dentry)
159{
160 return (unsigned long *) &dentry->d_fsdata;
161}
162
163struct ovl_inode {
164 union {
165 struct ovl_dir_cache *cache; /* directory */
166 const char *lowerdata_redirect; /* regular file */
167 };
168 const char *redirect;
169 u64 version;
170 unsigned long flags;
171 struct inode vfs_inode;
172 struct dentry *__upperdentry;
173 struct ovl_entry *oe;
174
175 /* synchronize copy up and more */
176 struct mutex lock;
177};
178
179static inline struct ovl_inode *OVL_I(struct inode *inode)
180{
181 return container_of(inode, struct ovl_inode, vfs_inode);
182}
183
184static inline struct ovl_entry *OVL_I_E(struct inode *inode)
185{
186 return inode ? OVL_I(inode)->oe : NULL;
187}
188
189static inline struct ovl_entry *OVL_E(struct dentry *dentry)
190{
191 return OVL_I_E(inode: d_inode(dentry));
192}
193
194static inline struct dentry *ovl_upperdentry_dereference(struct ovl_inode *oi)
195{
196 return READ_ONCE(oi->__upperdentry);
197}
198

source code of linux/fs/overlayfs/ovl_entry.h