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
   8 struct 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
  22 struct mnt_pcp {
  23         int mnt_count;
  24         int mnt_writers;
  25 };
  26
  27 struct mountpoint {
  28         struct hlist_node m_hash;
  29         struct dentry *m_dentry;
  30         struct hlist_head m_list;
  31         int m_count;
  32 };
  33
  34 struct 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
  77 static inline struct mount *real_mount(struct vfsmount *mnt)
  78 {
  79         return container_of(mnt, struct mount, mnt);
  80 }
  81
  82 static inline int mnt_has_parent(struct mount *mnt)
  83 {
  84         return mnt != mnt->mnt_parent;
  85 }
  86
  87 static 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
  93 extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *);
  94
  95 extern int __legitimize_mnt(struct vfsmount *, unsigned);
  96 extern bool legitimize_mnt(struct vfsmount *, unsigned);
  97
  98 static 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
 104 extern void __detach_mounts(struct dentry *dentry);
 105
 106 static inline void detach_mounts(struct dentry *dentry)
 107 {
 108         if (!d_mountpoint(dentry))
 109                 return;
 110         __detach_mounts(dentry);
 111 }
 112
 113 static inline void get_mnt_ns(struct mnt_namespace *ns)
 114 {
 115         atomic_inc(&ns->count);
 116 }
 117
 118 extern seqlock_t mount_lock;
 119
 120 static inline void lock_mount_hash(void)
 121 {
 122         write_seqlock(&mount_lock);
 123 }
 124
 125 static inline void unlock_mount_hash(void)
 126 {
 127         write_sequnlock(&mount_lock);
 128 }
 129
 130 struct 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
 139 extern const struct seq_operations mounts_op;
 140
 141 extern bool __is_local_mountpoint(struct dentry *dentry);
 142 static 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 }