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        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        struct hlist_node mnt_mp_list;  /* list mounts with the same mountpoint */
  62        struct list_head mnt_umounting; /* list entry for umount propagation */
  63#ifdef CONFIG_FSNOTIFY
  64        struct fsnotify_mark_connector __rcu *mnt_fsnotify_marks;
  65        __u32 mnt_fsnotify_mask;
  66#endif
  67        int mnt_id;                     /* mount identifier */
  68        int mnt_group_id;               /* peer group identifier */
  69        int mnt_expiry_mark;            /* true if marked for expiry */
  70        struct hlist_head mnt_pins;
  71        struct fs_pin mnt_umount;
  72        struct dentry *mnt_ex_mountpoint;
  73} __randomize_layout;
  74
  75#define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */
  76
  77static inline struct mount *real_mount(struct vfsmount *mnt)
  78{
  79        return container_of(mnt, struct mount, mnt);
  80}
  81
  82static inline int mnt_has_parent(struct mount *mnt)
  83{
  84        return mnt != mnt->mnt_parent;
  85}
  86
  87static inline int is_mounted(struct vfsmount *mnt)
  88{
  89        /* neither detached nor internal? */
  90        return !IS_ERR_OR_NULL(real_mount(mnt)->mnt_ns);
  91}
  92
  93extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *);
  94
  95extern int __legitimize_mnt(struct vfsmount *, unsigned);
  96extern bool legitimize_mnt(struct vfsmount *, unsigned);
  97
  98static inline bool __path_is_mountpoint(const struct path *path)
  99{
 100        struct mount *m = __lookup_mnt(path->mnt, path->dentry);
 101        return m && likely(!(m->mnt.mnt_flags & MNT_SYNC_UMOUNT));
 102}
 103
 104extern void __detach_mounts(struct dentry *dentry);
 105
 106static inline void detach_mounts(struct dentry *dentry)
 107{
 108        if (!d_mountpoint(dentry))
 109                return;
 110        __detach_mounts(dentry);
 111}
 112
 113static inline void get_mnt_ns(struct mnt_namespace *ns)
 114{
 115        atomic_inc(&ns->count);
 116}
 117
 118extern seqlock_t mount_lock;
 119
 120static inline void lock_mount_hash(void)
 121{
 122        write_seqlock(&mount_lock);
 123}
 124
 125static inline void unlock_mount_hash(void)
 126{
 127        write_sequnlock(&mount_lock);
 128}
 129
 130struct proc_mounts {
 131        struct mnt_namespace *ns;
 132        struct path root;
 133        int (*show)(struct seq_file *, struct vfsmount *);
 134        void *cached_mount;
 135        u64 cached_event;
 136        loff_t cached_index;
 137};
 138
 139extern const struct seq_operations mounts_op;
 140
 141extern bool __is_local_mountpoint(struct dentry *dentry);
 142static inline bool is_local_mountpoint(struct dentry *dentry)
 143{
 144        if (!d_mountpoint(dentry))
 145                return false;
 146
 147        return __is_local_mountpoint(dentry);
 148}
 149
 150static inline bool is_anon_ns(struct mnt_namespace *ns)
 151{
 152        return ns->seq == 0;
 153}
 154