fs/overlayfs/ovl_entry.h

   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
  11 struct ovl_config {
  12         char *lowerdir;
  13         char *upperdir;
  14         char *workdir;
  15         bool default_permissions;
  16         bool redirect_dir;
  17         bool index;
  18 };
  19
  20 struct ovl_layer {
  21         struct vfsmount *mnt;
  22         dev_t pseudo_dev;
  23 };
  24
  25 struct ovl_path {
  26         struct ovl_layer *layer;
  27         struct dentry *dentry;
  28 };
  29
  30 /* private information held for overlayfs's superblock */
  31 struct ovl_fs {
  32         struct vfsmount *upper_mnt;
  33         unsigned numlower;
  34         struct ovl_layer *lower_layers;
  35         /* workbasedir is the path at workdir= mount option */
  36         struct dentry *workbasedir;
  37         /* workdir is the 'work' directory under workbasedir */
  38         struct dentry *workdir;
  39         /* index directory listing overlay inodes by origin file handle */
  40         struct dentry *indexdir;
  41         long namelen;
  42         /* pathnames of lower and upper dirs, for show_options */
  43         struct ovl_config config;
  44         /* creds of process who forced instantiation of super block */
  45         const struct cred *creator_cred;
  46         bool tmpfile;
  47         bool noxattr;
  48         /* sb common to all layers */
  49         struct super_block *same_sb;
  50         /* Did we take the inuse lock? */
  51         bool upperdir_locked;
  52         bool workdir_locked;
  53 };
  54
  55 /* private information held for every overlayfs dentry */
  56 struct ovl_entry {
  57         union {
  58                 struct {
  59                         unsigned long has_upper;
  60                         bool opaque;
  61                 };
  62                 struct rcu_head rcu;
  63         };
  64         unsigned numlower;
  65         struct ovl_path lowerstack[];
  66 };
  67
  68 struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
  69
  70 struct ovl_inode {
  71         struct ovl_dir_cache *cache;
  72         const char *redirect;
  73         u64 version;
  74         unsigned long flags;
  75         struct inode vfs_inode;
  76         struct dentry *__upperdentry;
  77         struct inode *lower;
  78
  79         /* synchronize copy up and more */
  80         struct mutex lock;
  81 };
  82
  83 static inline struct ovl_inode *OVL_I(struct inode *inode)
  84 {
  85         return container_of(inode, struct ovl_inode, vfs_inode);
  86 }
  87
  88 static inline struct dentry *ovl_upperdentry_dereference(struct ovl_inode *oi)
  89 {
  90         return READ_ONCE(oi->__upperdentry);
  91 }