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 *lowerdir; 10 char *upperdir; 11 char *workdir; 12 bool default_permissions; 13 bool redirect_dir; 14 bool redirect_follow; 15 const char *redirect_mode; 16 bool index; 17 bool uuid; 18 bool nfs_export; 19 int xino; 20 bool metacopy; 21 bool userxattr; 22 bool ovl_volatile; 23 }; 24 25 struct ovl_sb { 26 struct super_block *sb; 27 dev_t pseudo_dev; 28 /* Unusable (conflicting) uuid */ 29 bool bad_uuid; 30 /* Used as a lower layer (but maybe also as upper) */ 31 bool is_lower; 32 }; 33 34 struct ovl_layer { 35 /* ovl_free_fs() relies on @mnt being the first member! */ 36 struct vfsmount *mnt; 37 /* Trap in ovl inode cache */ 38 struct inode *trap; 39 struct ovl_sb *fs; 40 /* Index of this layer in fs root (upper idx == 0) */ 41 int idx; 42 /* One fsid per unique underlying sb (upper fsid == 0) */ 43 int fsid; 44 }; 45 46 /* 47 * ovl_free_fs() relies on @mnt being the first member when unmounting 48 * the private mounts created for each layer. Let's check both the 49 * offset and type. 50 */ 51 static_assert(offsetof(struct ovl_layer, mnt) == 0); 52 static_assert(__same_type(typeof_member(struct ovl_layer, mnt), struct vfsmount *)); 53 54 struct ovl_path { 55 const struct ovl_layer *layer; 56 struct dentry *dentry; 57 }; 58 59 struct ovl_entry { 60 unsigned int __numlower; 61 struct ovl_path __lowerstack[]; 62 }; 63 64 /* private information held for overlayfs's superblock */ 65 struct ovl_fs { 66 unsigned int numlayer; 67 /* Number of unique fs among layers including upper fs */ 68 unsigned int numfs; 69 /* Number of data-only lower layers */ 70 unsigned int numdatalayer; 71 const struct ovl_layer *layers; 72 struct ovl_sb *fs; 73 /* workbasedir is the path at workdir= mount option */ 74 struct dentry *workbasedir; 75 /* workdir is the 'work' directory under workbasedir */ 76 struct dentry *workdir; 77 /* index directory listing overlay inodes by origin file handle */ 78 struct dentry *indexdir; 79 long namelen; 80 /* pathnames of lower and upper dirs, for show_options */ 81 struct ovl_config config; 82 /* creds of process who forced instantiation of super block */ 83 const struct cred *creator_cred; 84 bool tmpfile; 85 bool noxattr; 86 /* Did we take the inuse lock? */ 87 bool upperdir_locked; 88 bool workdir_locked; 89 /* Traps in ovl inode cache */ 90 struct inode *workbasedir_trap; 91 struct inode *workdir_trap; 92 struct inode *indexdir_trap; 93 /* -1: disabled, 0: same fs, 1..32: number of unused ino bits */ 94 int xino_mode; 95 /* For allocation of non-persistent inode numbers */ 96 atomic_long_t last_ino; 97 /* Shared whiteout cache */ 98 struct dentry *whiteout; 99 bool no_shared_whiteout; 100 /* r/o snapshot of upperdir sb's only taken on volatile mounts */ 101 errseq_t errseq; 102 }; 103 104 105 /* Number of lower layers, not including data-only layers */ 106 static inline unsigned int ovl_numlowerlayer(struct ovl_fs *ofs) 107 { 108 return ofs->numlayer - ofs->numdatalayer - 1; 109 } 110 111 static inline struct vfsmount *ovl_upper_mnt(struct ovl_fs *ofs) 112 { 113 return ofs->layers[0].mnt; 114 } 115 116 static inline struct mnt_idmap *ovl_upper_mnt_idmap(struct ovl_fs *ofs) 117 { 118 return mnt_idmap(ovl_upper_mnt(ofs)); 119 } 120 121 static inline struct ovl_fs *OVL_FS(struct super_block *sb) 122 { 123 return (struct ovl_fs *)sb->s_fs_info; 124 } 125 126 static inline bool ovl_should_sync(struct ovl_fs *ofs) 127 { 128 return !ofs->config.ovl_volatile; 129 } 130 131 static inline unsigned int ovl_numlower(struct ovl_entry *oe) 132 { 133 return oe ? oe->__numlower : 0; 134 } 135 136 static inline struct ovl_path *ovl_lowerstack(struct ovl_entry *oe) 137 { 138 return ovl_numlower(oe) ? oe->__lowerstack : NULL; 139 } 140 141 static inline struct ovl_path *ovl_lowerpath(struct ovl_entry *oe) 142 { 143 return ovl_lowerstack(oe); 144 } 145 146 static inline struct ovl_path *ovl_lowerdata(struct ovl_entry *oe) 147 { 148 struct ovl_path *lowerstack = ovl_lowerstack(oe); 149 150 return lowerstack ? &lowerstack[oe->__numlower - 1] : NULL; 151 } 152 153 /* May return NULL if lazy lookup of lowerdata is needed */ 154 static inline struct dentry *ovl_lowerdata_dentry(struct ovl_entry *oe) 155 { 156 struct ovl_path *lowerdata = ovl_lowerdata(oe); 157 158 return lowerdata ? READ_ONCE(lowerdata->dentry) : NULL; 159 } 160 161 /* private information held for every overlayfs dentry */ 162 static inline unsigned long *OVL_E_FLAGS(struct dentry *dentry) 163 { 164 return (unsigned long *) &dentry->d_fsdata; 165 } 166 167 struct ovl_inode { 168 union { 169 struct ovl_dir_cache *cache; /* directory */ 170 const char *lowerdata_redirect; /* regular file */ 171 }; 172 const char *redirect; 173 u64 version; 174 unsigned long flags; 175 struct inode vfs_inode; 176 struct dentry *__upperdentry; 177 struct ovl_entry *oe; 178 179 /* synchronize copy up and more */ 180 struct mutex lock; 181 }; 182 183 static inline struct ovl_inode *OVL_I(struct inode *inode) 184 { 185 return container_of(inode, struct ovl_inode, vfs_inode); 186 } 187 188 static inline struct ovl_entry *OVL_I_E(struct inode *inode) 189 { 190 return inode ? OVL_I(inode)->oe : NULL; 191 } 192 193 static inline struct ovl_entry *OVL_E(struct dentry *dentry) 194 { 195 return OVL_I_E(d_inode(dentry)); 196 } 197 198 static inline struct dentry *ovl_upperdentry_dereference(struct ovl_inode *oi) 199 { 200 return READ_ONCE(oi->__upperdentry); 201 } 202