xref: /linux/fs/mount.h (revision 9020d0d844ad58a051f90b1e5b82ba34123925b9)
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 
real_mount(struct vfsmount * mnt)84 static inline struct mount *real_mount(struct vfsmount *mnt)
85 {
86 	return container_of(mnt, struct mount, mnt);
87 }
88 
mnt_has_parent(struct mount * mnt)89 static inline int mnt_has_parent(struct mount *mnt)
90 {
91 	return mnt != mnt->mnt_parent;
92 }
93 
is_mounted(struct vfsmount * mnt)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 
__path_is_mountpoint(const struct path * path)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 
detach_mounts(struct dentry * dentry)112 static inline void detach_mounts(struct dentry *dentry)
113 {
114 	if (!d_mountpoint(dentry))
115 		return;
116 	__detach_mounts(dentry);
117 }
118 
get_mnt_ns(struct mnt_namespace * ns)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);
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 
is_anon_ns(struct mnt_namespace * ns)143 static inline bool is_anon_ns(struct mnt_namespace *ns)
144 {
145 	return ns->seq == 0;
146 }
147 
move_from_ns(struct mount * mnt,struct list_head * dt_list)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);
lookup_next_mnt_ns(struct mnt_namespace * mntns)158 static inline struct mnt_namespace *lookup_next_mnt_ns(struct mnt_namespace *mntns)
159 {
160 	return __lookup_next_mnt_ns(mntns, false);
161 }
lookup_prev_mnt_ns(struct mnt_namespace * mntns)162 static inline struct mnt_namespace *lookup_prev_mnt_ns(struct mnt_namespace *mntns)
163 {
164 	return __lookup_next_mnt_ns(mntns, true);
165 }
to_mnt_ns(struct ns_common * ns)166 static inline struct mnt_namespace *to_mnt_ns(struct ns_common *ns)
167 {
168 	return container_of(ns, struct mnt_namespace, ns);
169 }
170