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