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 */
ovl_numlowerlayer(struct ovl_fs * ofs)96  static inline unsigned int ovl_numlowerlayer(struct ovl_fs *ofs)
97  {
98  	return ofs->numlayer - ofs->numdatalayer - 1;
99  }
100  
ovl_upper_mnt(struct ovl_fs * ofs)101  static inline struct vfsmount *ovl_upper_mnt(struct ovl_fs *ofs)
102  {
103  	return ofs->layers[0].mnt;
104  }
105  
ovl_upper_mnt_idmap(struct ovl_fs * ofs)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  
OVL_FS(struct super_block * sb)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  
ovl_should_sync(struct ovl_fs * ofs)121  static inline bool ovl_should_sync(struct ovl_fs *ofs)
122  {
123  	return !ofs->config.ovl_volatile;
124  }
125  
ovl_numlower(struct ovl_entry * oe)126  static inline unsigned int ovl_numlower(struct ovl_entry *oe)
127  {
128  	return oe ? oe->__numlower : 0;
129  }
130  
ovl_lowerstack(struct ovl_entry * oe)131  static inline struct ovl_path *ovl_lowerstack(struct ovl_entry *oe)
132  {
133  	return ovl_numlower(oe) ? oe->__lowerstack : NULL;
134  }
135  
ovl_lowerpath(struct ovl_entry * oe)136  static inline struct ovl_path *ovl_lowerpath(struct ovl_entry *oe)
137  {
138  	return ovl_lowerstack(oe);
139  }
140  
ovl_lowerdata(struct ovl_entry * oe)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 */
ovl_lowerdata_dentry(struct ovl_entry * oe)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 */
OVL_E_FLAGS(struct dentry * 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  
OVL_I(struct inode * inode)178  static inline struct ovl_inode *OVL_I(struct inode *inode)
179  {
180  	return container_of(inode, struct ovl_inode, vfs_inode);
181  }
182  
OVL_I_E(struct inode * inode)183  static inline struct ovl_entry *OVL_I_E(struct inode *inode)
184  {
185  	return inode ? OVL_I(inode)->oe : NULL;
186  }
187  
OVL_E(struct dentry * dentry)188  static inline struct ovl_entry *OVL_E(struct dentry *dentry)
189  {
190  	return OVL_I_E(d_inode(dentry));
191  }
192  
ovl_upperdentry_dereference(struct ovl_inode * oi)193  static inline struct dentry *ovl_upperdentry_dereference(struct ovl_inode *oi)
194  {
195  	return READ_ONCE(oi->__upperdentry);
196  }
197