xref: /linux/fs/mount.h (revision 1fbde52bde73e5a4c90577bce935e966a1ba1387)
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  	/*
12  	 * Traversal and modification of .list is protected by either
13  	 * - taking namespace_sem for write, OR
14  	 * - taking namespace_sem for read AND taking .ns_lock.
15  	 */
16  	struct list_head	list;
17  	spinlock_t		ns_lock;
18  	struct user_namespace	*user_ns;
19  	struct ucounts		*ucounts;
20  	u64			seq;	/* Sequence number to prevent loops */
21  	wait_queue_head_t poll;
22  	u64 event;
23  	unsigned int		mounts; /* # of mounts in the namespace */
24  	unsigned int		pending_mounts;
25  } __randomize_layout;
26  
27  struct mnt_pcp {
28  	int mnt_count;
29  	int mnt_writers;
30  };
31  
32  struct mountpoint {
33  	struct hlist_node m_hash;
34  	struct dentry *m_dentry;
35  	struct hlist_head m_list;
36  	int m_count;
37  };
38  
39  struct mount {
40  	struct hlist_node mnt_hash;
41  	struct mount *mnt_parent;
42  	struct dentry *mnt_mountpoint;
43  	struct vfsmount mnt;
44  	union {
45  		struct rcu_head mnt_rcu;
46  		struct llist_node mnt_llist;
47  	};
48  #ifdef CONFIG_SMP
49  	struct mnt_pcp __percpu *mnt_pcp;
50  #else
51  	int mnt_count;
52  	int mnt_writers;
53  #endif
54  	struct list_head mnt_mounts;	/* list of children, anchored here */
55  	struct list_head mnt_child;	/* and going through their mnt_child */
56  	struct list_head mnt_instance;	/* mount instance on sb->s_mounts */
57  	const char *mnt_devname;	/* Name of device e.g. /dev/dsk/hda1 */
58  	struct list_head mnt_list;
59  	struct list_head mnt_expire;	/* link in fs-specific expiry list */
60  	struct list_head mnt_share;	/* circular list of shared mounts */
61  	struct list_head mnt_slave_list;/* list of slave mounts */
62  	struct list_head mnt_slave;	/* slave list entry */
63  	struct mount *mnt_master;	/* slave is on master->mnt_slave_list */
64  	struct mnt_namespace *mnt_ns;	/* containing namespace */
65  	struct mountpoint *mnt_mp;	/* where is it mounted */
66  	union {
67  		struct hlist_node mnt_mp_list;	/* list mounts with the same mountpoint */
68  		struct hlist_node mnt_umount;
69  	};
70  	struct list_head mnt_umounting; /* list entry for umount propagation */
71  #ifdef CONFIG_FSNOTIFY
72  	struct fsnotify_mark_connector __rcu *mnt_fsnotify_marks;
73  	__u32 mnt_fsnotify_mask;
74  #endif
75  	int mnt_id;			/* mount identifier */
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  	struct mount cursor;
131  };
132  
133  extern const struct seq_operations mounts_op;
134  
135  extern bool __is_local_mountpoint(struct dentry *dentry);
136  static inline bool is_local_mountpoint(struct dentry *dentry)
137  {
138  	if (!d_mountpoint(dentry))
139  		return false;
140  
141  	return __is_local_mountpoint(dentry);
142  }
143  
144  static inline bool is_anon_ns(struct mnt_namespace *ns)
145  {
146  	return ns->seq == 0;
147  }
148  
149  extern void mnt_cursor_del(struct mnt_namespace *ns, struct mount *cursor);
150