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	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
 27struct mnt_pcp {
 28	int mnt_count;
 29	int mnt_writers;
 30};
 31
 32struct mountpoint {
 33	struct hlist_node m_hash;
 34	struct dentry *m_dentry;
 35	struct hlist_head m_list;
 36	int m_count;
 37};
 38
 39struct 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
 84static inline struct mount *real_mount(struct vfsmount *mnt)
 85{
 86	return container_of(mnt, struct mount, mnt);
 87}
 88
 89static inline int mnt_has_parent(struct mount *mnt)
 90{
 91	return mnt != mnt->mnt_parent;
 92}
 93
 94static 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
100extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *);
101
102extern int __legitimize_mnt(struct vfsmount *, unsigned);
103
104static 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
110extern void __detach_mounts(struct dentry *dentry);
111
112static inline void detach_mounts(struct dentry *dentry)
113{
114	if (!d_mountpoint(dentry))
115		return;
116	__detach_mounts(dentry);
117}
118
119static inline void get_mnt_ns(struct mnt_namespace *ns)
120{
121	refcount_inc(&ns->ns.count);
122}
123
124extern seqlock_t mount_lock;
125
126struct 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
133extern const struct seq_operations mounts_op;
134
135extern bool __is_local_mountpoint(struct dentry *dentry);
136static 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
144static inline bool is_anon_ns(struct mnt_namespace *ns)
145{
146	return ns->seq == 0;
147}
148
149extern void mnt_cursor_del(struct mnt_namespace *ns, struct mount *cursor);