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         /* Trap in ovl inode cache */
  33         struct inode *trap;
  34         struct ovl_sb *fs;
  35         /* Index of this layer in fs root (upper idx == 0) */
  36         int idx;
  37         /* One fsid per unique underlying sb (upper fsid == 0) */
  38         int fsid;
  39 };
  40
  41 struct ovl_path {
  42         struct ovl_layer *layer;
  43         struct dentry *dentry;
  44 };
  45
  46 /* private information held for overlayfs's superblock */
  47 struct ovl_fs {
  48         struct vfsmount *upper_mnt;
  49         unsigned int numlower;
  50         /* Number of unique lower sb that differ from upper sb */
  51         unsigned int numlowerfs;
  52         struct ovl_layer *lower_layers;
  53         struct ovl_sb *lower_fs;
  54         /* workbasedir is the path at workdir= mount option */
  55         struct dentry *workbasedir;
  56         /* workdir is the 'work' directory under workbasedir */
  57         struct dentry *workdir;
  58         /* index directory listing overlay inodes by origin file handle */
  59         struct dentry *indexdir;
  60         long namelen;
  61         /* pathnames of lower and upper dirs, for show_options */
  62         struct ovl_config config;
  63         /* creds of process who forced instantiation of super block */
  64         const struct cred *creator_cred;
  65         bool tmpfile;
  66         bool noxattr;
  67         /* Did we take the inuse lock? */
  68         bool upperdir_locked;
  69         bool workdir_locked;
  70         /* Traps in ovl inode cache */
  71         struct inode *upperdir_trap;
  72         struct inode *workbasedir_trap;
  73         struct inode *workdir_trap;
  74         struct inode *indexdir_trap;
  75         /* Inode numbers in all layers do not use the high xino_bits */
  76         unsigned int xino_bits;
  77 };
  78
  79 /* private information held for every overlayfs dentry */
  80 struct ovl_entry {
  81         union {
  82                 struct {
  83                         unsigned long flags;
  84                 };
  85                 struct rcu_head rcu;
  86         };
  87         unsigned numlower;
  88         struct ovl_path lowerstack[];
  89 };
  90
  91 struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
  92
  93 static inline struct ovl_entry *OVL_E(struct dentry *dentry)
  94 {
  95         return (struct ovl_entry *) dentry->d_fsdata;
  96 }
  97
  98 struct ovl_inode {
  99         union {
 100                 struct ovl_dir_cache *cache;    /* directory */
 101                 struct inode *lowerdata;        /* regular file */
 102         };
 103         const char *redirect;
 104         u64 version;
 105         unsigned long flags;
 106         struct inode vfs_inode;
 107         struct dentry *__upperdentry;
 108         struct inode *lower;
 109
 110         /* synchronize copy up and more */
 111         struct mutex lock;
 112 };
 113
 114 static inline struct ovl_inode *OVL_I(struct inode *inode)
 115 {
 116         return container_of(inode, struct ovl_inode, vfs_inode);
 117 }
 118
 119 static inline struct dentry *ovl_upperdentry_dereference(struct ovl_inode *oi)
 120 {
 121         return READ_ONCE(oi->__upperdentry);
 122 }