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
  8struct mnt_namespace {
  9	atomic_t		count;
 10	struct ns_common	ns;
 11	struct mount *	root;
 12	struct list_head	list;
 13	struct user_namespace	*user_ns;
 14	struct ucounts		*ucounts;
 15	u64			seq;	/* Sequence number to prevent loops */
 16	wait_queue_head_t poll;
 17	u64 event;
 18	unsigned int		mounts; /* # of mounts in the namespace */
 19	unsigned int		pending_mounts;
 20} __randomize_layout;
 21
 22struct mnt_pcp {
 23	int mnt_count;
 24	int mnt_writers;
 25};
 26
 27struct mountpoint {
 28	struct hlist_node m_hash;
 29	struct dentry *m_dentry;
 30	struct hlist_head m_list;
 31	int m_count;
 32};
 33
 34struct mount {
 35	struct hlist_node mnt_hash;
 36	struct mount *mnt_parent;
 37	struct dentry *mnt_mountpoint;
 38	struct vfsmount mnt;
 39	union {
 40		struct rcu_head mnt_rcu;
 41		struct llist_node mnt_llist;
 42	};
 43#ifdef CONFIG_SMP
 44	struct mnt_pcp __percpu *mnt_pcp;
 45#else
 46	int mnt_count;
 47	int mnt_writers;
 48#endif
 49	struct list_head mnt_mounts;	/* list of children, anchored here */
 50	struct list_head mnt_child;	/* and going through their mnt_child */
 51	struct list_head mnt_instance;	/* mount instance on sb->s_mounts */
 52	const char *mnt_devname;	/* Name of device e.g. /dev/dsk/hda1 */
 53	struct list_head mnt_list;
 54	struct list_head mnt_expire;	/* link in fs-specific expiry list */
 55	struct list_head mnt_share;	/* circular list of shared mounts */
 56	struct list_head mnt_slave_list;/* list of slave mounts */
 57	struct list_head mnt_slave;	/* slave list entry */
 58	struct mount *mnt_master;	/* slave is on master->mnt_slave_list */
 59	struct mnt_namespace *mnt_ns;	/* containing namespace */
 60	struct mountpoint *mnt_mp;	/* where is it mounted */
 61	union {
 62		struct hlist_node mnt_mp_list;	/* list mounts with the same mountpoint */
 63		struct hlist_node mnt_umount;
 64	};
 65	struct list_head mnt_umounting; /* list entry for umount propagation */
 66#ifdef CONFIG_FSNOTIFY
 67	struct fsnotify_mark_connector __rcu *mnt_fsnotify_marks;
 68	__u32 mnt_fsnotify_mask;
 69#endif
 70	int mnt_id;			/* mount identifier */
 71	int mnt_group_id;		/* peer group identifier */
 72	int mnt_expiry_mark;		/* true if marked for expiry */
 73	struct hlist_head mnt_pins;
 74	struct hlist_head mnt_stuck_children;
 75} __randomize_layout;
 76
 77#define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */
 78
 79static inline struct mount *real_mount(struct vfsmount *mnt)
 80{
 81	return container_of(mnt, struct mount, mnt);
 82}
 83
 84static inline int mnt_has_parent(struct mount *mnt)
 85{
 86	return mnt != mnt->mnt_parent;
 87}
 88
 89static inline int is_mounted(struct vfsmount *mnt)
 90{
 91	/* neither detached nor internal? */
 92	return !IS_ERR_OR_NULL(real_mount(mnt)->mnt_ns);
 93}
 94
 95extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *);
 96
 97extern int __legitimize_mnt(struct vfsmount *, unsigned);
 98extern bool legitimize_mnt(struct vfsmount *, unsigned);
 99
100static inline bool __path_is_mountpoint(const struct path *path)
101{
102	struct mount *m = __lookup_mnt(path->mnt, path->dentry);
103	return m && likely(!(m->mnt.mnt_flags & MNT_SYNC_UMOUNT));
104}
105
106extern void __detach_mounts(struct dentry *dentry);
107
108static inline void detach_mounts(struct dentry *dentry)
109{
110	if (!d_mountpoint(dentry))
111		return;
112	__detach_mounts(dentry);
113}
114
115static inline void get_mnt_ns(struct mnt_namespace *ns)
116{
117	atomic_inc(&ns->count);
118}
119
120extern seqlock_t mount_lock;
121
122static inline void lock_mount_hash(void)
123{
124	write_seqlock(&mount_lock);
125}
126
127static inline void unlock_mount_hash(void)
128{
129	write_sequnlock(&mount_lock);
130}
131
132struct proc_mounts {
133	struct mnt_namespace *ns;
134	struct path root;
135	int (*show)(struct seq_file *, struct vfsmount *);
136	void *cached_mount;
137	u64 cached_event;
138	loff_t cached_index;
139};
140
141extern const struct seq_operations mounts_op;
142
143extern bool __is_local_mountpoint(struct dentry *dentry);
144static inline bool is_local_mountpoint(struct dentry *dentry)
145{
146	if (!d_mountpoint(dentry))
147		return false;
148
149	return __is_local_mountpoint(dentry);
150}
151
152static inline bool is_anon_ns(struct mnt_namespace *ns)
153{
154	return ns->seq == 0;
155}