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