fs/mount.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #include <linux/mount.h>
   3 #include <linux/seq_file.h>
   4 #include <linux/poll.h>
   5 #include <linux/ns_common.h>
   6 #include <linux/fs_pin.h>
   7
   8 struct mnt_namespace {
   9         struct ns_common        ns;
  10         struct mount *  root;
  11         struct {
  12                 struct rb_root  mounts;          /* Protected by namespace_sem */
  13                 struct rb_node  *mnt_last_node;  /* last (rightmost) mount in the rbtree */
  14                 struct rb_node  *mnt_first_node; /* first (leftmost) mount in the rbtree */
  15         };
  16         struct user_namespace   *user_ns;
  17         struct ucounts          *ucounts;
  18         u64                     seq;    /* Sequence number to prevent loops */
  19         union {
  20                 wait_queue_head_t       poll;
  21                 struct rcu_head         mnt_ns_rcu;
  22         };
  23         u64 event;
  24         unsigned int            nr_mounts; /* # of mounts in the namespace */
  25         unsigned int            pending_mounts;
  26         struct rb_node          mnt_ns_tree_node; /* node in the mnt_ns_tree */
  27         struct list_head        mnt_ns_list; /* entry in the sequential list of mounts namespace */
  28         refcount_t              passive; /* number references not pinning @mounts */
  29 } __randomize_layout;
  30
  31 struct mnt_pcp {
  32         int mnt_count;
  33         int mnt_writers;
  34 };
  35
  36 struct mountpoint {
  37         struct hlist_node m_hash;
  38         struct dentry *m_dentry;
  39         struct hlist_head m_list;
  40         int m_count;
  41 };
  42
  43 struct mount {
  44         struct hlist_node mnt_hash;
  45         struct mount *mnt_parent;
  46         struct dentry *mnt_mountpoint;
  47         struct vfsmount mnt;
  48         union {
  49                 struct rb_node mnt_node; /* node in the ns->mounts rbtree */
  50                 struct rcu_head mnt_rcu;
  51                 struct llist_node mnt_llist;
  52         };
  53 #ifdef CONFIG_SMP
  54         struct mnt_pcp __percpu *mnt_pcp;
  55 #else
  56         int mnt_count;
  57         int mnt_writers;
  58 #endif
  59         struct list_head mnt_mounts;    /* list of children, anchored here */
  60         struct list_head mnt_child;     /* and going through their mnt_child */
  61         struct list_head mnt_instance;  /* mount instance on sb->s_mounts */
  62         const char *mnt_devname;        /* Name of device e.g. /dev/dsk/hda1 */
  63         struct list_head mnt_list;
  64         struct list_head mnt_expire;    /* link in fs-specific expiry list */
  65         struct list_head mnt_share;     /* circular list of shared mounts */
  66         struct list_head mnt_slave_list;/* list of slave mounts */
  67         struct list_head mnt_slave;     /* slave list entry */
  68         struct mount *mnt_master;       /* slave is on master->mnt_slave_list */
  69         struct mnt_namespace *mnt_ns;   /* containing namespace */
  70         struct mountpoint *mnt_mp;      /* where is it mounted */
  71         union {
  72                 struct hlist_node mnt_mp_list;  /* list mounts with the same mountpoint */
  73                 struct hlist_node mnt_umount;
  74         };
  75         struct list_head mnt_umounting; /* list entry for umount propagation */
  76 #ifdef CONFIG_FSNOTIFY
  77         struct fsnotify_mark_connector __rcu *mnt_fsnotify_marks;
  78         __u32 mnt_fsnotify_mask;
  79 #endif
  80         int mnt_id;                     /* mount identifier, reused */
  81         u64 mnt_id_unique;              /* mount ID unique until reboot */
  82         int mnt_group_id;               /* peer group identifier */
  83         int mnt_expiry_mark;            /* true if marked for expiry */
  84         struct hlist_head mnt_pins;
  85         struct hlist_head mnt_stuck_children;
  86 } __randomize_layout;
  87
  88 #define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */
  89
  90 static inline struct mount *real_mount(struct vfsmount *mnt)
  91 {
  92         return container_of(mnt, struct mount, mnt);
  93 }
  94
  95 static inline int mnt_has_parent(struct mount *mnt)
  96 {
  97         return mnt != mnt->mnt_parent;
  98 }
  99
 100 static inline int is_mounted(struct vfsmount *mnt)
 101 {
 102         /* neither detached nor internal? */
 103         return !IS_ERR_OR_NULL(real_mount(mnt)->mnt_ns);
 104 }
 105
 106 extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *);
 107
 108 extern int __legitimize_mnt(struct vfsmount *, unsigned);
 109
 110 static inline bool __path_is_mountpoint(const struct path *path)
 111 {
 112         struct mount *m = __lookup_mnt(path->mnt, path->dentry);
 113         return m && likely(!(m->mnt.mnt_flags & MNT_SYNC_UMOUNT));
 114 }
 115
 116 extern void __detach_mounts(struct dentry *dentry);
 117
 118 static inline void detach_mounts(struct dentry *dentry)
 119 {
 120         if (!d_mountpoint(dentry))
 121                 return;
 122         __detach_mounts(dentry);
 123 }
 124
 125 static inline void get_mnt_ns(struct mnt_namespace *ns)
 126 {
 127         refcount_inc(&ns->ns.count);
 128 }
 129
 130 extern seqlock_t mount_lock;
 131
 132 struct proc_mounts {
 133         struct mnt_namespace *ns;
 134         struct path root;
 135         int (*show)(struct seq_file *, struct vfsmount *);
 136 };
 137
 138 extern const struct seq_operations mounts_op;
 139
 140 extern bool __is_local_mountpoint(struct dentry *dentry);
 141 static inline bool is_local_mountpoint(struct dentry *dentry)
 142 {
 143         if (!d_mountpoint(dentry))
 144                 return false;
 145
 146         return __is_local_mountpoint(dentry);
 147 }
 148
 149 static inline bool is_anon_ns(struct mnt_namespace *ns)
 150 {
 151         return ns->seq == 0;
 152 }
 153
 154 static inline bool mnt_ns_attached(const struct mount *mnt)
 155 {
 156         return !RB_EMPTY_NODE(&mnt->mnt_node);
 157 }
 158
 159 static inline void move_from_ns(struct mount *mnt, struct list_head *dt_list)
 160 {
 161         struct mnt_namespace *ns = mnt->mnt_ns;
 162         WARN_ON(!mnt_ns_attached(mnt));
 163         if (ns->mnt_last_node == &mnt->mnt_node)
 164                 ns->mnt_last_node = rb_prev(&mnt->mnt_node);
 165         if (ns->mnt_first_node == &mnt->mnt_node)
 166                 ns->mnt_first_node = rb_next(&mnt->mnt_node);
 167         rb_erase(&mnt->mnt_node, &ns->mounts);
 168         RB_CLEAR_NODE(&mnt->mnt_node);
 169         list_add_tail(&mnt->mnt_list, dt_list);
 170 }
 171
 172 bool has_locked_children(struct mount *mnt, struct dentry *dentry);
 173 struct mnt_namespace *get_sequential_mnt_ns(struct mnt_namespace *mnt_ns,
 174                                             bool previous);
 175
 176 static inline struct mnt_namespace *to_mnt_ns(struct ns_common *ns)
 177 {
 178         return container_of(ns, struct mnt_namespace, ns);
 179 }