LXR linux/fs/overlayfs/ovl

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