LXR linux/fs/mount.h

   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);
 103extern bool legitimize_mnt(struct vfsmount *, unsigned);
 104
 105static inline bool __path_is_mountpoint(const struct path *path)
 106{
 107        struct mount *m = __lookup_mnt(path->mnt, path->dentry);
 108        return m && likely(!(m->mnt.mnt_flags & MNT_SYNC_UMOUNT));
 109}
 110
 111extern void __detach_mounts(struct dentry *dentry);
 112
 113static inline void detach_mounts(struct dentry *dentry)
 114{
 115        if (!d_mountpoint(dentry))
 116                return;
 117        __detach_mounts(dentry);
 118}
 119
 120static inline void get_mnt_ns(struct mnt_namespace *ns)
 121{
 122        refcount_inc(&ns->ns.count);
 123}
 124
 125extern seqlock_t mount_lock;
 126
 127struct proc_mounts {
 128        struct mnt_namespace *ns;
 129        struct path root;
 130        int (*show)(struct seq_file *, struct vfsmount *);
 131        struct mount cursor;
 132};
 133
 134extern const struct seq_operations mounts_op;
 135
 136extern bool __is_local_mountpoint(struct dentry *dentry);
 137static inline bool is_local_mountpoint(struct dentry *dentry)
 138{
 139        if (!d_mountpoint(dentry))
 140                return false;
 141
 142        return __is_local_mountpoint(dentry);
 143}
 144
 145static inline bool is_anon_ns(struct mnt_namespace *ns)
 146{
 147        return ns->seq == 0;
 148}
 149
 150extern void mnt_cursor_del(struct mnt_namespace *ns, struct mount *cursor);
 151