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 *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
24 struct 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
33 struct 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
47 struct ovl_path {
48 const struct ovl_layer *layer;
49 struct dentry *dentry;
50 };
51
52 struct ovl_entry {
53 unsigned int __numlower;
54 struct ovl_path __lowerstack[];
55 };
56
57 /* private information held for overlayfs's superblock */
58 struct 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 */
96 static inline unsigned int ovl_numlowerlayer(struct ovl_fs *ofs)
97 {
98 return ofs->numlayer - ofs->numdatalayer - 1;
99 }
100
101 static inline struct vfsmount *ovl_upper_mnt(struct ovl_fs *ofs)
102 {
103 return ofs->layers[0].mnt;
104 }
105
106 static inline struct mnt_idmap *ovl_upper_mnt_idmap(struct ovl_fs *ofs)
107 {
108 return mnt_idmap(ovl_upper_mnt(ofs));
109 }
110
111 extern struct file_system_type ovl_fs_type;
112
113 static 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
121 static inline bool ovl_should_sync(struct ovl_fs *ofs)
122 {
123 return !ofs->config.ovl_volatile;
124 }
125
126 static inline unsigned int ovl_numlower(struct ovl_entry *oe)
127 {
128 return oe ? oe->__numlower : 0;
129 }
130
131 static inline struct ovl_path *ovl_lowerstack(struct ovl_entry *oe)
132 {
133 return ovl_numlower(oe) ? oe->__lowerstack : NULL;
134 }
135
136 static inline struct ovl_path *ovl_lowerpath(struct ovl_entry *oe)
137 {
138 return ovl_lowerstack(oe);
139 }
140
141 static 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 */
149 static 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 */
157 static inline unsigned long *OVL_E_FLAGS(struct dentry *dentry)
158 {
159 return (unsigned long *) &dentry->d_fsdata;
160 }
161
162 struct 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
178 static inline struct ovl_inode *OVL_I(struct inode *inode)
179 {
180 return container_of(inode, struct ovl_inode, vfs_inode);
181 }
182
183 static inline struct ovl_entry *OVL_I_E(struct inode *inode)
184 {
185 return inode ? OVL_I(inode)->oe : NULL;
186 }
187
188 static inline struct ovl_entry *OVL_E(struct dentry *dentry)
189 {
190 return OVL_I_E(d_inode(dentry));
191 }
192
193 static inline struct dentry *ovl_upperdentry_dereference(struct ovl_inode *oi)
194 {
195 return READ_ONCE(oi->__upperdentry);
196 }
197
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