/* SPDX-License-Identifier: GPL-2.0 */
#include <linux/mount.h>
#include <linux/seq_file.h>
#include <linux/poll.h>
#include <linux/ns_common.h>
#include <linux/fs_pin.h>

extern struct file_system_type nullfs_fs_type;
extern struct list_head notify_list;

struct mnt_namespace {
        struct ns_common        ns;
        struct mount *  root;
        struct {
                struct rb_root  mounts;          /* Protected by namespace_sem */
                struct rb_node  *mnt_last_node;  /* last (rightmost) mount in the rbtree */
                struct rb_node  *mnt_first_node; /* first (leftmost) mount in the rbtree */
        };
        struct user_namespace   *user_ns;
        struct ucounts          *ucounts;
        wait_queue_head_t       poll;
        u64                     seq_origin; /* Sequence number of origin mount namespace */
        u64 event;
#ifdef CONFIG_FSNOTIFY
        __u32                   n_fsnotify_mask;
        struct fsnotify_mark_connector __rcu *n_fsnotify_marks;
#endif
        unsigned int            nr_mounts; /* # of mounts in the namespace */
        unsigned int            pending_mounts;
        refcount_t              passive; /* number references not pinning @mounts */
        bool                    is_anon;
} __randomize_layout;

struct mnt_pcp {
        int mnt_count;
        int mnt_writers;
};

struct mountpoint {
        struct hlist_node m_hash;
        struct dentry *m_dentry;
        struct hlist_head m_list;
};

struct mount {
        struct hlist_node mnt_hash;
        struct mount *mnt_parent;
        struct dentry *mnt_mountpoint;
        struct vfsmount mnt;
        union {
                struct rb_node mnt_node; /* node in the ns->mounts rbtree */
                struct rcu_head mnt_rcu;
                struct llist_node mnt_llist;
        };
#ifdef CONFIG_SMP
        struct mnt_pcp __percpu *mnt_pcp;
#else
        int mnt_count;
        int mnt_writers;
#endif
        struct list_head mnt_mounts;    /* list of children, anchored here */
        struct list_head mnt_child;     /* and going through their mnt_child */
        struct mount *mnt_next_for_sb;  /* the next two fields are hlist_node, */
        struct mount * __aligned(1) *mnt_pprev_for_sb;
                                        /* except that LSB of pprev is stolen */
#define WRITE_HOLD 1                    /* ... for use by mnt_hold_writers() */
        const char *mnt_devname;        /* Name of device e.g. /dev/dsk/hda1 */
        struct list_head mnt_list;
        struct list_head mnt_expire;    /* link in fs-specific expiry list */
        struct list_head mnt_share;     /* circular list of shared mounts */
        struct hlist_head mnt_slave_list;/* list of slave mounts */
        struct hlist_node mnt_slave;    /* slave list entry */
        struct mount *mnt_master;       /* slave is on master->mnt_slave_list */
        struct mnt_namespace *mnt_ns;   /* containing namespace */
        struct mountpoint *mnt_mp;      /* where is it mounted */
        union {
                struct hlist_node mnt_mp_list;  /* list mounts with the same mountpoint */
                struct hlist_node mnt_umount;
        };
#ifdef CONFIG_FSNOTIFY
        struct fsnotify_mark_connector __rcu *mnt_fsnotify_marks;
        __u32 mnt_fsnotify_mask;
        struct list_head to_notify;     /* need to queue notification */
        struct mnt_namespace *prev_ns;  /* previous namespace (NULL if none) */
#endif
        int mnt_t_flags;                /* namespace_sem-protected flags */
        int mnt_id;                     /* mount identifier, reused */
        u64 mnt_id_unique;              /* mount ID unique until reboot */
        int mnt_group_id;               /* peer group identifier */
        int mnt_expiry_mark;            /* true if marked for expiry */
        struct hlist_head mnt_pins;
        struct hlist_head mnt_stuck_children;
        struct mount *overmount;        /* mounted on ->mnt_root */
} __randomize_layout;

enum {
        T_SHARED                = 1, /* mount is shared */
        T_UNBINDABLE            = 2, /* mount is unbindable */
        T_MARKED                = 4, /* internal mark for propagate_... */
        T_UMOUNT_CANDIDATE      = 8, /* for propagate_umount */

        /*
         * T_SHARED_MASK is the set of flags that should be cleared when a
         * mount becomes shared.  Currently, this is only the flag that says a
         * mount cannot be bind mounted, since this is how we create a mount
         * that shares events with another mount.  If you add a new T_*
         * flag, consider how it interacts with shared mounts.
         */
        T_SHARED_MASK   = T_UNBINDABLE,
};

#define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */

static inline struct mount *real_mount(struct vfsmount *mnt)
{
        return container_of(mnt, struct mount, mnt);
}

static inline int mnt_has_parent(const struct mount *mnt)
{
        return mnt != mnt->mnt_parent;
}

static inline int is_mounted(struct vfsmount *mnt)
{
        /* neither detached nor internal? */
        return !IS_ERR_OR_NULL(real_mount(mnt)->mnt_ns);
}

extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *);

extern int __legitimize_mnt(struct vfsmount *, unsigned);

static inline bool __path_is_mountpoint(const struct path *path)
{
        struct mount *m = __lookup_mnt(path->mnt, path->dentry);
        return m && likely(!(m->mnt.mnt_flags & MNT_SYNC_UMOUNT));
}

extern void __detach_mounts(struct dentry *dentry);

static inline void detach_mounts(struct dentry *dentry)
{
        if (!d_mountpoint(dentry))
                return;
        __detach_mounts(dentry);
}

static inline void get_mnt_ns(struct mnt_namespace *ns)
{
        ns_ref_inc(ns);
}

extern seqlock_t mount_lock;

DEFINE_LOCK_GUARD_0(mount_writer, write_seqlock(&mount_lock),
                    write_sequnlock(&mount_lock))
DEFINE_LOCK_GUARD_0(mount_locked_reader, read_seqlock_excl(&mount_lock),
                    read_sequnlock_excl(&mount_lock))

struct proc_mounts {
        struct mnt_namespace *ns;
        struct path root;
        int (*show)(struct seq_file *, struct vfsmount *);
};

extern const struct seq_operations mounts_op;

extern bool __is_local_mountpoint(const struct dentry *dentry);
static inline bool is_local_mountpoint(const struct dentry *dentry)
{
        if (!d_mountpoint(dentry))
                return false;

        return __is_local_mountpoint(dentry);
}

static inline bool is_anon_ns(struct mnt_namespace *ns)
{
        return ns->is_anon;
}

static inline bool anon_ns_root(const struct mount *m)
{
        struct mnt_namespace *ns = READ_ONCE(m->mnt_ns);

        return !IS_ERR_OR_NULL(ns) && is_anon_ns(ns) && m == ns->root;
}

static inline bool mnt_ns_attached(const struct mount *mnt)
{
        return !RB_EMPTY_NODE(&mnt->mnt_node);
}

static inline bool mnt_ns_empty(const struct mnt_namespace *ns)
{
        return RB_EMPTY_ROOT(&ns->mounts);
}

static inline void move_from_ns(struct mount *mnt)
{
        struct mnt_namespace *ns = mnt->mnt_ns;
        WARN_ON(!mnt_ns_attached(mnt));
        if (ns->mnt_last_node == &mnt->mnt_node)
                ns->mnt_last_node = rb_prev(&mnt->mnt_node);
        if (ns->mnt_first_node == &mnt->mnt_node)
                ns->mnt_first_node = rb_next(&mnt->mnt_node);
        rb_erase(&mnt->mnt_node, &ns->mounts);
        RB_CLEAR_NODE(&mnt->mnt_node);
}

bool has_locked_children(struct mount *mnt, struct dentry *dentry);
struct mnt_namespace *get_sequential_mnt_ns(struct mnt_namespace *mnt_ns,
                                            bool previous);

static inline struct mnt_namespace *to_mnt_ns(struct ns_common *ns)
{
        return container_of(ns, struct mnt_namespace, ns);
}

#ifdef CONFIG_FSNOTIFY
static inline void mnt_notify_add(struct mount *m)
{
        /* Optimize the case where there are no watches */
        if ((m->mnt_ns && m->mnt_ns->n_fsnotify_marks) ||
            (m->prev_ns && m->prev_ns->n_fsnotify_marks))
                list_add_tail(&m->to_notify, &notify_list);
        else
                m->prev_ns = m->mnt_ns;
}
#else
static inline void mnt_notify_add(struct mount *m)
{
}
#endif

static inline struct mount *topmost_overmount(struct mount *m)
{
        while (m->overmount)
                m = m->overmount;
        return m;
}

static inline bool __test_write_hold(struct mount * __aligned(1) *val)
{
        return (unsigned long)val & WRITE_HOLD;
}

static inline bool test_write_hold(const struct mount *m)
{
        return __test_write_hold(m->mnt_pprev_for_sb);
}

static inline void set_write_hold(struct mount *m)
{
        m->mnt_pprev_for_sb = (void *)((unsigned long)m->mnt_pprev_for_sb
                                       | WRITE_HOLD);
}

static inline void clear_write_hold(struct mount *m)
{
        m->mnt_pprev_for_sb = (void *)((unsigned long)m->mnt_pprev_for_sb
                                       & ~WRITE_HOLD);
}

struct mnt_namespace *mnt_ns_from_dentry(struct dentry *dentry);