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' or 'index' directory under workbasedir */ 67 struct dentry *workdir; 68 long namelen; 69 /* pathnames of lower and upper dirs, for show_options */ 70 struct ovl_config config; 71 /* creds of process who forced instantiation of super block */ 72 const struct cred *creator_cred; 73 bool tmpfile; 74 bool noxattr; 75 bool nofh; 76 /* Did we take the inuse lock? */ 77 bool upperdir_locked; 78 bool workdir_locked; 79 /* Traps in ovl inode cache */ 80 struct inode *workbasedir_trap; 81 struct inode *workdir_trap; 82 /* -1: disabled, 0: same fs, 1..32: number of unused ino bits */ 83 int xino_mode; 84 /* For allocation of non-persistent inode numbers */ 85 atomic_long_t last_ino; 86 /* Shared whiteout cache */ 87 struct dentry *whiteout; 88 bool no_shared_whiteout; 89 /* r/o snapshot of upperdir sb's only taken on volatile mounts */ 90 errseq_t errseq; 91 }; 92 93 /* Number of lower layers, not including data-only layers */ 94 static inline unsigned int ovl_numlowerlayer(struct ovl_fs *ofs) 95 { 96 return ofs->numlayer - ofs->numdatalayer - 1; 97 } 98 99 static inline struct vfsmount *ovl_upper_mnt(struct ovl_fs *ofs) 100 { 101 return ofs->layers[0].mnt; 102 } 103 104 static inline struct mnt_idmap *ovl_upper_mnt_idmap(struct ovl_fs *ofs) 105 { 106 return mnt_idmap(ovl_upper_mnt(ofs)); 107 } 108 109 extern struct file_system_type ovl_fs_type; 110 111 static inline struct ovl_fs *OVL_FS(struct super_block *sb) 112 { 113 if (IS_ENABLED(CONFIG_OVERLAY_FS_DEBUG)) 114 WARN_ON_ONCE(sb->s_type != &ovl_fs_type); 115 116 return (struct ovl_fs *)sb->s_fs_info; 117 } 118 119 static inline bool ovl_should_sync(struct ovl_fs *ofs) 120 { 121 return !ofs->config.ovl_volatile; 122 } 123 124 static inline unsigned int ovl_numlower(struct ovl_entry *oe) 125 { 126 return oe ? oe->__numlower : 0; 127 } 128 129 static inline struct ovl_path *ovl_lowerstack(struct ovl_entry *oe) 130 { 131 return ovl_numlower(oe) ? oe->__lowerstack : NULL; 132 } 133 134 static inline struct ovl_path *ovl_lowerpath(struct ovl_entry *oe) 135 { 136 return ovl_lowerstack(oe); 137 } 138 139 static inline struct ovl_path *ovl_lowerdata(struct ovl_entry *oe) 140 { 141 struct ovl_path *lowerstack = ovl_lowerstack(oe); 142 143 return lowerstack ? &lowerstack[oe->__numlower - 1] : NULL; 144 } 145 146 /* May return NULL if lazy lookup of lowerdata is needed */ 147 static inline struct dentry *ovl_lowerdata_dentry(struct ovl_entry *oe) 148 { 149 struct ovl_path *lowerdata = ovl_lowerdata(oe); 150 151 return lowerdata ? READ_ONCE(lowerdata->dentry) : NULL; 152 } 153 154 /* private information held for every overlayfs dentry */ 155 static inline unsigned long *OVL_E_FLAGS(struct dentry *dentry) 156 { 157 return (unsigned long *) &dentry->d_fsdata; 158 } 159 160 struct ovl_inode { 161 union { 162 struct ovl_dir_cache *cache; /* directory */ 163 const char *lowerdata_redirect; /* regular file */ 164 }; 165 const char *redirect; 166 u64 version; 167 unsigned long flags; 168 struct inode vfs_inode; 169 struct dentry *__upperdentry; 170 struct ovl_entry *oe; 171 172 /* synchronize copy up and more */ 173 struct mutex lock; 174 }; 175 176 static inline struct ovl_inode *OVL_I(struct inode *inode) 177 { 178 return container_of(inode, struct ovl_inode, vfs_inode); 179 } 180 181 static inline struct ovl_entry *OVL_I_E(struct inode *inode) 182 { 183 return inode ? OVL_I(inode)->oe : NULL; 184 } 185 186 static inline struct ovl_entry *OVL_E(struct dentry *dentry) 187 { 188 return OVL_I_E(d_inode(dentry)); 189 } 190 191 static inline struct dentry *ovl_upperdentry_dereference(struct ovl_inode *oi) 192 { 193 return READ_ONCE(oi->__upperdentry); 194 } 195