fs/overlayfs/overlayfs.h

   1 /*
   2  *
   3  * Copyright (C) 2011 Novell Inc.
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 as published by
   7  * the Free Software Foundation.
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/uuid.h>
  12
  13 enum ovl_path_type {
  14         __OVL_PATH_UPPER        = (1 << 0),
  15         __OVL_PATH_MERGE        = (1 << 1),
  16         __OVL_PATH_ORIGIN       = (1 << 2),
  17 };
  18
  19 #define OVL_TYPE_UPPER(type)    ((type) & __OVL_PATH_UPPER)
  20 #define OVL_TYPE_MERGE(type)    ((type) & __OVL_PATH_MERGE)
  21 #define OVL_TYPE_ORIGIN(type)   ((type) & __OVL_PATH_ORIGIN)
  22
  23 #define OVL_XATTR_PREFIX XATTR_TRUSTED_PREFIX "overlay."
  24 #define OVL_XATTR_OPAQUE OVL_XATTR_PREFIX "opaque"
  25 #define OVL_XATTR_REDIRECT OVL_XATTR_PREFIX "redirect"
  26 #define OVL_XATTR_ORIGIN OVL_XATTR_PREFIX "origin"
  27 #define OVL_XATTR_IMPURE OVL_XATTR_PREFIX "impure"
  28 #define OVL_XATTR_NLINK OVL_XATTR_PREFIX "nlink"
  29
  30 enum ovl_flag {
  31         OVL_IMPURE,
  32         OVL_INDEX,
  33 };
  34
  35 /*
  36  * The tuple (fh,uuid) is a universal unique identifier for a copy up origin,
  37  * where:
  38  * origin.fh    - exported file handle of the lower file
  39  * origin.uuid  - uuid of the lower filesystem
  40  */
  41 #define OVL_FH_VERSION  0
  42 #define OVL_FH_MAGIC    0xfb
  43
  44 /* CPU byte order required for fid decoding:  */
  45 #define OVL_FH_FLAG_BIG_ENDIAN  (1 << 0)
  46 #define OVL_FH_FLAG_ANY_ENDIAN  (1 << 1)
  47 /* Is the real inode encoded in fid an upper inode? */
  48 #define OVL_FH_FLAG_PATH_UPPER  (1 << 2)
  49
  50 #define OVL_FH_FLAG_ALL (OVL_FH_FLAG_BIG_ENDIAN | OVL_FH_FLAG_ANY_ENDIAN)
  51
  52 #if defined(__LITTLE_ENDIAN)
  53 #define OVL_FH_FLAG_CPU_ENDIAN 0
  54 #elif defined(__BIG_ENDIAN)
  55 #define OVL_FH_FLAG_CPU_ENDIAN OVL_FH_FLAG_BIG_ENDIAN
  56 #else
  57 #error Endianness not defined
  58 #endif
  59
  60 /* On-disk and in-memeory format for redirect by file handle */
  61 struct ovl_fh {
  62         u8 version;     /* 0 */
  63         u8 magic;       /* 0xfb */
  64         u8 len;         /* size of this header + size of fid */
  65         u8 flags;       /* OVL_FH_FLAG_* */
  66         u8 type;        /* fid_type of fid */
  67         uuid_t uuid;    /* uuid of filesystem */
  68         u8 fid[0];      /* file identifier */
  69 } __packed;
  70
  71 static inline int ovl_do_rmdir(struct inode *dir, struct dentry *dentry)
  72 {
  73         int err = vfs_rmdir(dir, dentry);
  74         pr_debug("rmdir(%pd2) = %i\n", dentry, err);
  75         return err;
  76 }
  77
  78 static inline int ovl_do_unlink(struct inode *dir, struct dentry *dentry)
  79 {
  80         int err = vfs_unlink(dir, dentry, NULL);
  81         pr_debug("unlink(%pd2) = %i\n", dentry, err);
  82         return err;
  83 }
  84
  85 static inline int ovl_do_link(struct dentry *old_dentry, struct inode *dir,
  86                               struct dentry *new_dentry, bool debug)
  87 {
  88         int err = vfs_link(old_dentry, dir, new_dentry, NULL);
  89         if (debug) {
  90                 pr_debug("link(%pd2, %pd2) = %i\n",
  91                          old_dentry, new_dentry, err);
  92         }
  93         return err;
  94 }
  95
  96 static inline int ovl_do_create(struct inode *dir, struct dentry *dentry,
  97                              umode_t mode, bool debug)
  98 {
  99         int err = vfs_create(dir, dentry, mode, true);
 100         if (debug)
 101                 pr_debug("create(%pd2, 0%o) = %i\n", dentry, mode, err);
 102         return err;
 103 }
 104
 105 static inline int ovl_do_mkdir(struct inode *dir, struct dentry *dentry,
 106                                umode_t mode, bool debug)
 107 {
 108         int err = vfs_mkdir(dir, dentry, mode);
 109         if (debug)
 110                 pr_debug("mkdir(%pd2, 0%o) = %i\n", dentry, mode, err);
 111         return err;
 112 }
 113
 114 static inline int ovl_do_mknod(struct inode *dir, struct dentry *dentry,
 115                                umode_t mode, dev_t dev, bool debug)
 116 {
 117         int err = vfs_mknod(dir, dentry, mode, dev);
 118         if (debug) {
 119                 pr_debug("mknod(%pd2, 0%o, 0%o) = %i\n",
 120                          dentry, mode, dev, err);
 121         }
 122         return err;
 123 }
 124
 125 static inline int ovl_do_symlink(struct inode *dir, struct dentry *dentry,
 126                                  const char *oldname, bool debug)
 127 {
 128         int err = vfs_symlink(dir, dentry, oldname);
 129         if (debug)
 130                 pr_debug("symlink(\"%s\", %pd2) = %i\n", oldname, dentry, err);
 131         return err;
 132 }
 133
 134 static inline int ovl_do_setxattr(struct dentry *dentry, const char *name,
 135                                   const void *value, size_t size, int flags)
 136 {
 137         int err = vfs_setxattr(dentry, name, value, size, flags);
 138         pr_debug("setxattr(%pd2, \"%s\", \"%*s\", 0x%x) = %i\n",
 139                  dentry, name, (int) size, (char *) value, flags, err);
 140         return err;
 141 }
 142
 143 static inline int ovl_do_removexattr(struct dentry *dentry, const char *name)
 144 {
 145         int err = vfs_removexattr(dentry, name);
 146         pr_debug("removexattr(%pd2, \"%s\") = %i\n", dentry, name, err);
 147         return err;
 148 }
 149
 150 static inline int ovl_do_rename(struct inode *olddir, struct dentry *olddentry,
 151                                 struct inode *newdir, struct dentry *newdentry,
 152                                 unsigned int flags)
 153 {
 154         int err;
 155
 156         pr_debug("rename(%pd2, %pd2, 0x%x)\n",
 157                  olddentry, newdentry, flags);
 158
 159         err = vfs_rename(olddir, olddentry, newdir, newdentry, NULL, flags);
 160
 161         if (err) {
 162                 pr_debug("...rename(%pd2, %pd2, ...) = %i\n",
 163                          olddentry, newdentry, err);
 164         }
 165         return err;
 166 }
 167
 168 static inline int ovl_do_whiteout(struct inode *dir, struct dentry *dentry)
 169 {
 170         int err = vfs_whiteout(dir, dentry);
 171         pr_debug("whiteout(%pd2) = %i\n", dentry, err);
 172         return err;
 173 }
 174
 175 static inline struct dentry *ovl_do_tmpfile(struct dentry *dentry, umode_t mode)
 176 {
 177         struct dentry *ret = vfs_tmpfile(dentry, mode, 0);
 178         int err = IS_ERR(ret) ? PTR_ERR(ret) : 0;
 179
 180         pr_debug("tmpfile(%pd2, 0%o) = %i\n", dentry, mode, err);
 181         return ret;
 182 }
 183
 184 /* util.c */
 185 int ovl_want_write(struct dentry *dentry);
 186 void ovl_drop_write(struct dentry *dentry);
 187 struct dentry *ovl_workdir(struct dentry *dentry);
 188 const struct cred *ovl_override_creds(struct super_block *sb);
 189 struct super_block *ovl_same_sb(struct super_block *sb);
 190 bool ovl_can_decode_fh(struct super_block *sb);
 191 struct dentry *ovl_indexdir(struct super_block *sb);
 192 struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
 193 bool ovl_dentry_remote(struct dentry *dentry);
 194 bool ovl_dentry_weird(struct dentry *dentry);
 195 enum ovl_path_type ovl_path_type(struct dentry *dentry);
 196 void ovl_path_upper(struct dentry *dentry, struct path *path);
 197 void ovl_path_lower(struct dentry *dentry, struct path *path);
 198 enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);
 199 struct dentry *ovl_dentry_upper(struct dentry *dentry);
 200 struct dentry *ovl_dentry_lower(struct dentry *dentry);
 201 struct dentry *ovl_dentry_real(struct dentry *dentry);
 202 struct inode *ovl_inode_upper(struct inode *inode);
 203 struct inode *ovl_inode_lower(struct inode *inode);
 204 struct inode *ovl_inode_real(struct inode *inode);
 205 struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry);
 206 void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache);
 207 bool ovl_dentry_is_opaque(struct dentry *dentry);
 208 bool ovl_dentry_is_whiteout(struct dentry *dentry);
 209 void ovl_dentry_set_opaque(struct dentry *dentry);
 210 bool ovl_dentry_has_upper_alias(struct dentry *dentry);
 211 void ovl_dentry_set_upper_alias(struct dentry *dentry);
 212 bool ovl_redirect_dir(struct super_block *sb);
 213 const char *ovl_dentry_get_redirect(struct dentry *dentry);
 214 void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect);
 215 void ovl_inode_init(struct inode *inode, struct dentry *upperdentry,
 216                     struct dentry *lowerdentry);
 217 void ovl_inode_update(struct inode *inode, struct dentry *upperdentry);
 218 void ovl_dentry_version_inc(struct dentry *dentry);
 219 u64 ovl_dentry_version_get(struct dentry *dentry);
 220 bool ovl_is_whiteout(struct dentry *dentry);
 221 struct file *ovl_path_open(struct path *path, int flags);
 222 int ovl_copy_up_start(struct dentry *dentry);
 223 void ovl_copy_up_end(struct dentry *dentry);
 224 bool ovl_check_dir_xattr(struct dentry *dentry, const char *name);
 225 int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
 226                        const char *name, const void *value, size_t size,
 227                        int xerr);
 228 int ovl_set_impure(struct dentry *dentry, struct dentry *upperdentry);
 229 void ovl_set_flag(unsigned long flag, struct inode *inode);
 230 bool ovl_test_flag(unsigned long flag, struct inode *inode);
 231 bool ovl_inuse_trylock(struct dentry *dentry);
 232 void ovl_inuse_unlock(struct dentry *dentry);
 233 int ovl_nlink_start(struct dentry *dentry, bool *locked);
 234 void ovl_nlink_end(struct dentry *dentry, bool locked);
 235
 236 static inline bool ovl_is_impuredir(struct dentry *dentry)
 237 {
 238         return ovl_check_dir_xattr(dentry, OVL_XATTR_IMPURE);
 239 }
 240
 241
 242 /* namei.c */
 243 int ovl_verify_origin(struct dentry *dentry, struct vfsmount *mnt,
 244                       struct dentry *origin, bool is_upper, bool set);
 245 int ovl_verify_index(struct dentry *index, struct path *lowerstack,
 246                      unsigned int numlower);
 247 int ovl_get_index_name(struct dentry *origin, struct qstr *name);
 248 int ovl_path_next(int idx, struct dentry *dentry, struct path *path);
 249 struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags);
 250 bool ovl_lower_positive(struct dentry *dentry);
 251
 252 /* readdir.c */
 253 extern const struct file_operations ovl_dir_operations;
 254 int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list);
 255 void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list);
 256 void ovl_cache_free(struct list_head *list);
 257 int ovl_check_d_type_supported(struct path *realpath);
 258 void ovl_workdir_cleanup(struct inode *dir, struct vfsmount *mnt,
 259                          struct dentry *dentry, int level);
 260 int ovl_indexdir_cleanup(struct dentry *dentry, struct vfsmount *mnt,
 261                          struct path *lowerstack, unsigned int numlower);
 262
 263 /* inode.c */
 264 int ovl_set_nlink_upper(struct dentry *dentry);
 265 int ovl_set_nlink_lower(struct dentry *dentry);
 266 unsigned int ovl_get_nlink(struct dentry *lowerdentry,
 267                            struct dentry *upperdentry,
 268                            unsigned int fallback);
 269 int ovl_setattr(struct dentry *dentry, struct iattr *attr);
 270 int ovl_getattr(const struct path *path, struct kstat *stat,
 271                 u32 request_mask, unsigned int flags);
 272 int ovl_permission(struct inode *inode, int mask);
 273 int ovl_xattr_set(struct dentry *dentry, const char *name, const void *value,
 274                   size_t size, int flags);
 275 int ovl_xattr_get(struct dentry *dentry, const char *name,
 276                   void *value, size_t size);
 277 ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size);
 278 struct posix_acl *ovl_get_acl(struct inode *inode, int type);
 279 int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags);
 280 int ovl_update_time(struct inode *inode, struct timespec *ts, int flags);
 281 bool ovl_is_private_xattr(const char *name);
 282
 283 struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev);
 284 struct inode *ovl_get_inode(struct dentry *dentry, struct dentry *upperdentry);
 285 static inline void ovl_copyattr(struct inode *from, struct inode *to)
 286 {
 287         to->i_uid = from->i_uid;
 288         to->i_gid = from->i_gid;
 289         to->i_mode = from->i_mode;
 290         to->i_atime = from->i_atime;
 291         to->i_mtime = from->i_mtime;
 292         to->i_ctime = from->i_ctime;
 293 }
 294
 295 /* dir.c */
 296 extern const struct inode_operations ovl_dir_inode_operations;
 297 struct dentry *ovl_lookup_temp(struct dentry *workdir);
 298 struct cattr {
 299         dev_t rdev;
 300         umode_t mode;
 301         const char *link;
 302 };
 303 int ovl_create_real(struct inode *dir, struct dentry *newdentry,
 304                     struct cattr *attr,
 305                     struct dentry *hardlink, bool debug);
 306 int ovl_cleanup(struct inode *dir, struct dentry *dentry);
 307
 308 /* copy_up.c */
 309 int ovl_copy_up(struct dentry *dentry);
 310 int ovl_copy_up_flags(struct dentry *dentry, int flags);
 311 int ovl_copy_xattr(struct dentry *old, struct dentry *new);
 312 int ovl_set_attr(struct dentry *upper, struct kstat *stat);
 313 struct ovl_fh *ovl_encode_fh(struct dentry *lower, bool is_upper);