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         /* Used as a lower layer (but maybe also as upper) */
  28         bool is_lower;
  29 };
  30
  31 struct ovl_layer {
  32         struct vfsmount *mnt;
  33         /* Trap in ovl inode cache */
  34         struct inode *trap;
  35         struct ovl_sb *fs;
  36         /* Index of this layer in fs root (upper idx == 0) */
  37         int idx;
  38         /* One fsid per unique underlying sb (upper fsid == 0) */
  39         int fsid;
  40 };
  41
  42 struct ovl_path {
  43         const struct ovl_layer *layer;
  44         struct dentry *dentry;
  45 };
  46
  47 /* private information held for overlayfs's superblock */
  48 struct ovl_fs {
  49         struct vfsmount *upper_mnt;
  50         unsigned int numlayer;
  51         /* Number of unique fs among layers including upper fs */
  52         unsigned int numfs;
  53         const struct ovl_layer *layers;
  54         struct ovl_sb *fs;
  55         /* workbasedir is the path at workdir= mount option */
  56         struct dentry *workbasedir;
  57         /* workdir is the 'work' directory under workbasedir */
  58         struct dentry *workdir;
  59         /* index directory listing overlay inodes by origin file handle */
  60         struct dentry *indexdir;
  61         long namelen;
  62         /* pathnames of lower and upper dirs, for show_options */
  63         struct ovl_config config;
  64         /* creds of process who forced instantiation of super block */
  65         const struct cred *creator_cred;
  66         bool tmpfile;
  67         bool noxattr;
  68         /* Did we take the inuse lock? */
  69         bool upperdir_locked;
  70         bool workdir_locked;
  71         /* Traps in ovl inode cache */
  72         struct inode *upperdir_trap;
  73         struct inode *workbasedir_trap;
  74         struct inode *workdir_trap;
  75         struct inode *indexdir_trap;
  76         /* -1: disabled, 0: same fs, 1..32: number of unused ino bits */
  77         int xino_mode;
  78         /* For allocation of non-persistent inode numbers */
  79         atomic_long_t last_ino;
  80 };
  81
  82 static inline struct ovl_fs *OVL_FS(struct super_block *sb)
  83 {
  84         return (struct ovl_fs *)sb->s_fs_info;
  85 }
  86
  87 /* private information held for every overlayfs dentry */
  88 struct ovl_entry {
  89         union {
  90                 struct {
  91                         unsigned long flags;
  92                 };
  93                 struct rcu_head rcu;
  94         };
  95         unsigned numlower;
  96         struct ovl_path lowerstack[];
  97 };
  98
  99 struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
 100
 101 static inline struct ovl_entry *OVL_E(struct dentry *dentry)
 102 {
 103         return (struct ovl_entry *) dentry->d_fsdata;
 104 }
 105
 106 struct ovl_inode {
 107         union {
 108                 struct ovl_dir_cache *cache;    /* directory */
 109                 struct inode *lowerdata;        /* regular file */
 110         };
 111         const char *redirect;
 112         u64 version;
 113         unsigned long flags;
 114         struct inode vfs_inode;
 115         struct dentry *__upperdentry;
 116         struct inode *lower;
 117
 118         /* synchronize copy up and more */
 119         struct mutex lock;
 120 };
 121
 122 static inline struct ovl_inode *OVL_I(struct inode *inode)
 123 {
 124         return container_of(inode, struct ovl_inode, vfs_inode);
 125 }
 126
 127 static inline struct dentry *ovl_upperdentry_dereference(struct ovl_inode *oi)
 128 {
 129         return READ_ONCE(oi->__upperdentry);
 130 }