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 }; 44 45 struct ovl_path { 46 const struct ovl_layer *layer; 47 struct dentry *dentry; 48 }; 49 50 struct ovl_entry { 51 unsigned int __numlower; 52 struct ovl_path __lowerstack[]; 53 }; 54 55 /* private information held for overlayfs's superblock */ 56 struct 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 */ ovl_numlowerlayer(struct ovl_fs * ofs)97static inline unsigned int ovl_numlowerlayer(struct ovl_fs *ofs) 98 { 99 return ofs->numlayer - ofs->numdatalayer - 1; 100 } 101 ovl_upper_mnt(struct ovl_fs * ofs)102static inline struct vfsmount *ovl_upper_mnt(struct ovl_fs *ofs) 103 { 104 return ofs->layers[0].mnt; 105 } 106 ovl_upper_mnt_idmap(struct ovl_fs * ofs)107static inline struct mnt_idmap *ovl_upper_mnt_idmap(struct ovl_fs *ofs) 108 { 109 return mnt_idmap(ovl_upper_mnt(ofs)); 110 } 111 112 extern struct file_system_type ovl_fs_type; 113 OVL_FS(struct super_block * sb)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 ovl_should_sync(struct ovl_fs * ofs)122static inline bool ovl_should_sync(struct ovl_fs *ofs) 123 { 124 return !ofs->config.ovl_volatile; 125 } 126 ovl_numlower(struct ovl_entry * oe)127static inline unsigned int ovl_numlower(struct ovl_entry *oe) 128 { 129 return oe ? oe->__numlower : 0; 130 } 131 ovl_lowerstack(struct ovl_entry * oe)132static inline struct ovl_path *ovl_lowerstack(struct ovl_entry *oe) 133 { 134 return ovl_numlower(oe) ? oe->__lowerstack : NULL; 135 } 136 ovl_lowerpath(struct ovl_entry * oe)137static inline struct ovl_path *ovl_lowerpath(struct ovl_entry *oe) 138 { 139 return ovl_lowerstack(oe); 140 } 141 ovl_lowerdata(struct ovl_entry * oe)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 */ ovl_lowerdata_dentry(struct ovl_entry * oe)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 */ OVL_E_FLAGS(struct dentry * dentry)158static inline unsigned long *OVL_E_FLAGS(struct dentry *dentry) 159 { 160 return (unsigned long *) &dentry->d_fsdata; 161 } 162 163 struct 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 OVL_I(struct inode * inode)179static inline struct ovl_inode *OVL_I(struct inode *inode) 180 { 181 return container_of(inode, struct ovl_inode, vfs_inode); 182 } 183 OVL_I_E(struct inode * inode)184static inline struct ovl_entry *OVL_I_E(struct inode *inode) 185 { 186 return inode ? OVL_I(inode)->oe : NULL; 187 } 188 OVL_E(struct dentry * dentry)189static inline struct ovl_entry *OVL_E(struct dentry *dentry) 190 { 191 return OVL_I_E(d_inode(dentry)); 192 } 193 ovl_upperdentry_dereference(struct ovl_inode * oi)194static inline struct dentry *ovl_upperdentry_dereference(struct ovl_inode *oi) 195 { 196 return READ_ONCE(oi->__upperdentry); 197 } 198