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         int xino;
  22         bool metacopy;
  23 };
  24
  25 struct ovl_sb {
  26         struct super_block *sb;
  27         dev_t pseudo_dev;
  28 };
  29
  30 struct 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
  39 struct ovl_path {
  40         struct ovl_layer *layer;
  41         struct dentry *dentry;
  42 };
  43
  44 /* private information held for overlayfs's superblock */
  45 struct 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 */
  73 struct 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
  84 struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
  85
  86 static inline struct ovl_entry *OVL_E(struct dentry *dentry)
  87 {
  88         return (struct ovl_entry *) dentry->d_fsdata;
  89 }
  90
  91 struct 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
 107 static inline struct ovl_inode *OVL_I(struct inode *inode)
 108 {
 109         return container_of(inode, struct ovl_inode, vfs_inode);
 110 }
 111
 112 static inline struct dentry *ovl_upperdentry_dereference(struct ovl_inode *oi)
 113 {
 114         return READ_ONCE(oi->__upperdentry);
 115 }