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