LXR linux/fs/overlayfs/ovl

   1/*
   2 *
   3 * Copyright (C) 2011 Novell Inc.
   4 * Copyright (C) 2016 Red Hat, Inc.
   5 *
   6 * This program is free software; you can redistribute it and/or modify it
   7 * under the terms of the GNU General Public License version 2 as published by
   8 * the Free Software Foundation.
   9 */
  10
  11struct ovl_config {
  12        char *lowerdir;
  13        char *upperdir;
  14        char *workdir;
  15        bool default_permissions;
  16        bool redirect_dir;
  17        bool redirect_follow;
  18        const char *redirect_mode;
  19        bool index;
  20        bool nfs_export;
  21        int xino;
  22        bool metacopy;
  23};
  24
  25struct ovl_sb {
  26        struct super_block *sb;
  27        dev_t pseudo_dev;
  28};
  29
  30struct ovl_layer {
  31        struct vfsmount *mnt;
  32        struct ovl_sb *fs;
  33        /* Index of this layer in fs root (upper idx == 0) */
  34        int idx;
  35        /* One fsid per unique underlying sb (upper fsid == 0) */
  36        int fsid;
  37};
  38
  39struct ovl_path {
  40        struct ovl_layer *layer;
  41        struct dentry *dentry;
  42};
  43
  44/* private information held for overlayfs's superblock */
  45struct ovl_fs {
  46        struct vfsmount *upper_mnt;
  47        unsigned int numlower;
  48        /* Number of unique lower sb that differ from upper sb */
  49        unsigned int numlowerfs;
  50        struct ovl_layer *lower_layers;
  51        struct ovl_sb *lower_fs;
  52        /* workbasedir is the path at workdir= mount option */
  53        struct dentry *workbasedir;
  54        /* workdir is the 'work' directory under workbasedir */
  55        struct dentry *workdir;
  56        /* index directory listing overlay inodes by origin file handle */
  57        struct dentry *indexdir;
  58        long namelen;
  59        /* pathnames of lower and upper dirs, for show_options */
  60        struct ovl_config config;
  61        /* creds of process who forced instantiation of super block */
  62        const struct cred *creator_cred;
  63        bool tmpfile;
  64        bool noxattr;
  65        /* Did we take the inuse lock? */
  66        bool upperdir_locked;
  67        bool workdir_locked;
  68        /* Inode numbers in all layers do not use the high xino_bits */
  69        unsigned int xino_bits;
  70};
  71
  72/* private information held for every overlayfs dentry */
  73struct ovl_entry {
  74        union {
  75                struct {
  76                        unsigned long flags;
  77                };
  78                struct rcu_head rcu;
  79        };
  80        unsigned numlower;
  81        struct ovl_path lowerstack[];
  82};
  83
  84struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
  85
  86static inline struct ovl_entry *OVL_E(struct dentry *dentry)
  87{
  88        return (struct ovl_entry *) dentry->d_fsdata;
  89}
  90
  91struct ovl_inode {
  92        union {
  93                struct ovl_dir_cache *cache;    /* directory */
  94                struct inode *lowerdata;        /* regular file */
  95        };
  96        const char *redirect;
  97        u64 version;
  98        unsigned long flags;
  99        struct inode vfs_inode;
 100        struct dentry *__upperdentry;
 101        struct inode *lower;
 102
 103        /* synchronize copy up and more */
 104        struct mutex lock;
 105};
 106
 107static inline struct ovl_inode *OVL_I(struct inode *inode)
 108{
 109        return container_of(inode, struct ovl_inode, vfs_inode);
 110}
 111
 112static inline struct dentry *ovl_upperdentry_dereference(struct ovl_inode *oi)
 113{
 114        return READ_ONCE(oi->__upperdentry);
 115}
 116