fs/overlayfs/ovl_entry.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  *
   4  * Copyright (C) 2011 Novell Inc.
   5  * Copyright (C) 2016 Red Hat, Inc.
   6  */
   7
   8 struct ovl_config {
   9         char *lowerdir;
  10         char *upperdir;
  11         char *workdir;
  12         bool default_permissions;
  13         bool redirect_dir;
  14         bool redirect_follow;
  15         const char *redirect_mode;
  16         bool index;
  17         bool nfs_export;
  18         int xino;
  19         bool metacopy;
  20 };
  21
  22 struct ovl_sb {
  23         struct super_block *sb;
  24         dev_t pseudo_dev;
  25         /* Unusable (conflicting) uuid */
  26         bool bad_uuid;
  27 };
  28
  29 struct ovl_layer {
  30         struct vfsmount *mnt;
  31         /* Trap in ovl inode cache */
  32         struct inode *trap;
  33         struct ovl_sb *fs;
  34         /* Index of this layer in fs root (upper idx == 0) */
  35         int idx;
  36         /* One fsid per unique underlying sb (upper fsid == 0) */
  37         int fsid;
  38 };
  39
  40 struct ovl_path {
  41         struct ovl_layer *layer;
  42         struct dentry *dentry;
  43 };
  44
  45 /* private information held for overlayfs's superblock */
  46 struct ovl_fs {
  47         struct vfsmount *upper_mnt;
  48         unsigned int numlower;
  49         /* Number of unique lower sb that differ from upper sb */
  50         unsigned int numlowerfs;
  51         struct ovl_layer *lower_layers;
  52         struct ovl_sb *lower_fs;
  53         /* workbasedir is the path at workdir= mount option */
  54         struct dentry *workbasedir;
  55         /* workdir is the 'work' directory under workbasedir */
  56         struct dentry *workdir;
  57         /* index directory listing overlay inodes by origin file handle */
  58         struct dentry *indexdir;
  59         long namelen;
  60         /* pathnames of lower and upper dirs, for show_options */
  61         struct ovl_config config;
  62         /* creds of process who forced instantiation of super block */
  63         const struct cred *creator_cred;
  64         bool tmpfile;
  65         bool noxattr;
  66         /* Did we take the inuse lock? */
  67         bool upperdir_locked;
  68         bool workdir_locked;
  69         /* Traps in ovl inode cache */
  70         struct inode *upperdir_trap;
  71         struct inode *workbasedir_trap;
  72         struct inode *workdir_trap;
  73         struct inode *indexdir_trap;
  74         /* Inode numbers in all layers do not use the high xino_bits */
  75         unsigned int xino_bits;
  76 };
  77
  78 /* private information held for every overlayfs dentry */
  79 struct ovl_entry {
  80         union {
  81                 struct {
  82                         unsigned long flags;
  83                 };
  84                 struct rcu_head rcu;
  85         };
  86         unsigned numlower;
  87         struct ovl_path lowerstack[];
  88 };
  89
  90 struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
  91
  92 static inline struct ovl_entry *OVL_E(struct dentry *dentry)
  93 {
  94         return (struct ovl_entry *) dentry->d_fsdata;
  95 }
  96
  97 struct ovl_inode {
  98         union {
  99                 struct ovl_dir_cache *cache;    /* directory */
 100                 struct inode *lowerdata;        /* regular file */
 101         };
 102         const char *redirect;
 103         u64 version;
 104         unsigned long flags;
 105         struct inode vfs_inode;
 106         struct dentry *__upperdentry;
 107         struct inode *lower;
 108
 109         /* synchronize copy up and more */
 110         struct mutex lock;
 111 };
 112
 113 static inline struct ovl_inode *OVL_I(struct inode *inode)
 114 {
 115         return container_of(inode, struct ovl_inode, vfs_inode);
 116 }
 117
 118 static inline struct dentry *ovl_upperdentry_dereference(struct ovl_inode *oi)
 119 {
 120         return READ_ONCE(oi->__upperdentry);
 121 }