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(mnt: 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(inode: 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 | |