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 redirect_follow;
  18         const char *redirect_mode;
  19         bool index;
  20         bool nfs_export;
  21 };
  22
  23 struct ovl_layer {
  24         struct vfsmount *mnt;
  25         dev_t pseudo_dev;
  26         /* Index of this layer in fs root (upper == 0) */
  27         int idx;
  28 };
  29
  30 struct ovl_path {
  31         struct ovl_layer *layer;
  32         struct dentry *dentry;
  33 };
  34
  35 /* private information held for overlayfs's superblock */
  36 struct ovl_fs {
  37         struct vfsmount *upper_mnt;
  38         unsigned numlower;
  39         struct ovl_layer *lower_layers;
  40         /* workbasedir is the path at workdir= mount option */
  41         struct dentry *workbasedir;
  42         /* workdir is the 'work' directory under workbasedir */
  43         struct dentry *workdir;
  44         /* index directory listing overlay inodes by origin file handle */
  45         struct dentry *indexdir;
  46         long namelen;
  47         /* pathnames of lower and upper dirs, for show_options */
  48         struct ovl_config config;
  49         /* creds of process who forced instantiation of super block */
  50         const struct cred *creator_cred;
  51         bool tmpfile;
  52         bool noxattr;
  53         /* sb common to all layers */
  54         struct super_block *same_sb;
  55         /* Did we take the inuse lock? */
  56         bool upperdir_locked;
  57         bool workdir_locked;
  58 };
  59
  60 /* private information held for every overlayfs dentry */
  61 struct ovl_entry {
  62         union {
  63                 struct {
  64                         unsigned long flags;
  65                 };
  66                 struct rcu_head rcu;
  67         };
  68         unsigned numlower;
  69         struct ovl_path lowerstack[];
  70 };
  71
  72 struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
  73
  74 static inline struct ovl_entry *OVL_E(struct dentry *dentry)
  75 {
  76         return (struct ovl_entry *) dentry->d_fsdata;
  77 }
  78
  79 struct ovl_inode {
  80         struct ovl_dir_cache *cache;
  81         const char *redirect;
  82         u64 version;
  83         unsigned long flags;
  84         struct inode vfs_inode;
  85         struct dentry *__upperdentry;
  86         struct inode *lower;
  87
  88         /* synchronize copy up and more */
  89         struct mutex lock;
  90 };
  91
  92 static inline struct ovl_inode *OVL_I(struct inode *inode)
  93 {
  94         return container_of(inode, struct ovl_inode, vfs_inode);
  95 }
  96
  97 static inline struct dentry *ovl_upperdentry_dereference(struct ovl_inode *oi)
  98 {
  99         return READ_ONCE(oi->__upperdentry);
 100 }