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 } __randomize_layout;
  20
  21 struct mnt_pcp {
  22         int mnt_count;
  23         int mnt_writers;
  24 };
  25
  26 struct mountpoint {
  27         struct hlist_node m_hash;
  28         struct dentry *m_dentry;
  29         struct hlist_head m_list;
  30         int m_count;
  31 };
  32
  33 struct mount {
  34         struct hlist_node mnt_hash;
  35         struct mount *mnt_parent;
  36         struct dentry *mnt_mountpoint;
  37         struct vfsmount mnt;
  38         union {
  39                 struct rcu_head mnt_rcu;
  40                 struct llist_node mnt_llist;
  41         };
  42 #ifdef CONFIG_SMP
  43         struct mnt_pcp __percpu *mnt_pcp;
  44 #else
  45         int mnt_count;
  46         int mnt_writers;
  47 #endif
  48         struct list_head mnt_mounts;    /* list of children, anchored here */
  49         struct list_head mnt_child;     /* and going through their mnt_child */
  50         struct list_head mnt_instance;  /* mount instance on sb->s_mounts */
  51         const char *mnt_devname;        /* Name of device e.g. /dev/dsk/hda1 */
  52         union {
  53                 struct rb_node mnt_node;        /* Under ns->mounts */
  54                 struct list_head mnt_list;
  55         };
  56         struct list_head mnt_expire;    /* link in fs-specific expiry list */
  57         struct list_head mnt_share;     /* circular list of shared mounts */
  58         struct list_head mnt_slave_list;/* list of slave mounts */
  59         struct list_head mnt_slave;     /* slave list entry */
  60         struct mount *mnt_master;       /* slave is on master->mnt_slave_list */
  61         struct mnt_namespace *mnt_ns;   /* containing namespace */
  62         struct mountpoint *mnt_mp;      /* where is it mounted */
  63         union {
  64                 struct hlist_node mnt_mp_list;  /* list mounts with the same mountpoint */
  65                 struct hlist_node mnt_umount;
  66         };
  67         struct list_head mnt_umounting; /* list entry for umount propagation */
  68 #ifdef CONFIG_FSNOTIFY
  69         struct fsnotify_mark_connector __rcu *mnt_fsnotify_marks;
  70         __u32 mnt_fsnotify_mask;
  71 #endif
  72         int mnt_id;                     /* mount identifier, reused */
  73         u64 mnt_id_unique;              /* mount ID unique until reboot */
  74         int mnt_group_id;               /* peer group identifier */
  75         int mnt_expiry_mark;            /* true if marked for expiry */
  76         struct hlist_head mnt_pins;
  77         struct hlist_head mnt_stuck_children;
  78 } __randomize_layout;
  79
  80 #define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */
  81
  82 static inline struct mount *real_mount(struct vfsmount *mnt)
  83 {
  84         return container_of(mnt, struct mount, mnt);
  85 }
  86
  87 static inline int mnt_has_parent(struct mount *mnt)
  88 {
  89         return mnt != mnt->mnt_parent;
  90 }
  91
  92 static inline int is_mounted(struct vfsmount *mnt)
  93 {
  94         /* neither detached nor internal? */
  95         return !IS_ERR_OR_NULL(real_mount(mnt)->mnt_ns);
  96 }
  97
  98 extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *);
  99
 100 extern int __legitimize_mnt(struct vfsmount *, unsigned);
 101
 102 static inline bool __path_is_mountpoint(const struct path *path)
 103 {
 104         struct mount *m = __lookup_mnt(path->mnt, path->dentry);
 105         return m && likely(!(m->mnt.mnt_flags & MNT_SYNC_UMOUNT));
 106 }
 107
 108 extern void __detach_mounts(struct dentry *dentry);
 109
 110 static inline void detach_mounts(struct dentry *dentry)
 111 {
 112         if (!d_mountpoint(dentry))
 113                 return;
 114         __detach_mounts(dentry);
 115 }
 116
 117 static inline void get_mnt_ns(struct mnt_namespace *ns)
 118 {
 119         refcount_inc(&ns->ns.count);
 120 }
 121
 122 extern seqlock_t mount_lock;
 123
 124 struct proc_mounts {
 125         struct mnt_namespace *ns;
 126         struct path root;
 127         int (*show)(struct seq_file *, struct vfsmount *);
 128 };
 129
 130 extern const struct seq_operations mounts_op;
 131
 132 extern bool __is_local_mountpoint(struct dentry *dentry);
 133 static inline bool is_local_mountpoint(struct dentry *dentry)
 134 {
 135         if (!d_mountpoint(dentry))
 136                 return false;
 137
 138         return __is_local_mountpoint(dentry);
 139 }
 140
 141 static inline bool is_anon_ns(struct mnt_namespace *ns)
 142 {
 143         return ns->seq == 0;
 144 }
 145
 146 static inline void move_from_ns(struct mount *mnt, struct list_head *dt_list)
 147 {
 148         WARN_ON(!(mnt->mnt.mnt_flags & MNT_ONRB));
 149         mnt->mnt.mnt_flags &= ~MNT_ONRB;
 150         rb_erase(&mnt->mnt_node, &mnt->mnt_ns->mounts);
 151         list_add_tail(&mnt->mnt_list, dt_list);
 152 }
 153
 154 extern void mnt_cursor_del(struct mnt_namespace *ns, struct mount *cursor);