LXR linux/include/linux/mount.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2/*
   3 *
   4 * Definitions for mount interface. This describes the in the kernel build 
   5 * linkedlist with mounted filesystems.
   6 *
   7 * Author:  Marco van Wieringen <mvw@planets.elm.net>
   8 *
   9 */
  10#ifndef _LINUX_MOUNT_H
  11#define _LINUX_MOUNT_H
  12
  13#include <linux/types.h>
  14#include <linux/list.h>
  15#include <linux/nodemask.h>
  16#include <linux/spinlock.h>
  17#include <linux/seqlock.h>
  18#include <linux/atomic.h>
  19
  20struct super_block;
  21struct vfsmount;
  22struct dentry;
  23struct mnt_namespace;
  24struct fs_context;
  25
  26#define MNT_NOSUID      0x01
  27#define MNT_NODEV       0x02
  28#define MNT_NOEXEC      0x04
  29#define MNT_NOATIME     0x08
  30#define MNT_NODIRATIME  0x10
  31#define MNT_RELATIME    0x20
  32#define MNT_READONLY    0x40    /* does the user want this to be r/o? */
  33#define MNT_NOSYMFOLLOW 0x80
  34
  35#define MNT_SHRINKABLE  0x100
  36#define MNT_WRITE_HOLD  0x200
  37
  38#define MNT_SHARED      0x1000  /* if the vfsmount is a shared mount */
  39#define MNT_UNBINDABLE  0x2000  /* if the vfsmount is a unbindable mount */
  40/*
  41 * MNT_SHARED_MASK is the set of flags that should be cleared when a
  42 * mount becomes shared.  Currently, this is only the flag that says a
  43 * mount cannot be bind mounted, since this is how we create a mount
  44 * that shares events with another mount.  If you add a new MNT_*
  45 * flag, consider how it interacts with shared mounts.
  46 */
  47#define MNT_SHARED_MASK (MNT_UNBINDABLE)
  48#define MNT_USER_SETTABLE_MASK  (MNT_NOSUID | MNT_NODEV | MNT_NOEXEC \
  49                                 | MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME \
  50                                 | MNT_READONLY | MNT_NOSYMFOLLOW)
  51#define MNT_ATIME_MASK (MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME )
  52
  53#define MNT_INTERNAL_FLAGS (MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL | \
  54                            MNT_DOOMED | MNT_SYNC_UMOUNT | MNT_MARKED | \
  55                            MNT_CURSOR)
  56
  57#define MNT_INTERNAL    0x4000
  58
  59#define MNT_LOCK_ATIME          0x040000
  60#define MNT_LOCK_NOEXEC         0x080000
  61#define MNT_LOCK_NOSUID         0x100000
  62#define MNT_LOCK_NODEV          0x200000
  63#define MNT_LOCK_READONLY       0x400000
  64#define MNT_LOCKED              0x800000
  65#define MNT_DOOMED              0x1000000
  66#define MNT_SYNC_UMOUNT         0x2000000
  67#define MNT_MARKED              0x4000000
  68#define MNT_UMOUNT              0x8000000
  69#define MNT_CURSOR              0x10000000
  70
  71struct vfsmount {
  72        struct dentry *mnt_root;        /* root of the mounted tree */
  73        struct super_block *mnt_sb;     /* pointer to superblock */
  74        int mnt_flags;
  75        struct user_namespace *mnt_userns;
  76} __randomize_layout;
  77
  78static inline struct user_namespace *mnt_user_ns(const struct vfsmount *mnt)
  79{
  80        /* Pairs with smp_store_release() in do_idmap_mount(). */
  81        return smp_load_acquire(&mnt->mnt_userns);
  82}
  83
  84struct file; /* forward dec */
  85struct path;
  86
  87extern int mnt_want_write(struct vfsmount *mnt);
  88extern int mnt_want_write_file(struct file *file);
  89extern void mnt_drop_write(struct vfsmount *mnt);
  90extern void mnt_drop_write_file(struct file *file);
  91extern void mntput(struct vfsmount *mnt);
  92extern struct vfsmount *mntget(struct vfsmount *mnt);
  93extern struct vfsmount *mnt_clone_internal(const struct path *path);
  94extern bool __mnt_is_readonly(struct vfsmount *mnt);
  95extern bool mnt_may_suid(struct vfsmount *mnt);
  96
  97struct path;
  98extern struct vfsmount *clone_private_mount(const struct path *path);
  99extern int __mnt_want_write(struct vfsmount *);
 100extern void __mnt_drop_write(struct vfsmount *);
 101
 102struct file_system_type;
 103extern struct vfsmount *fc_mount(struct fs_context *fc);
 104extern struct vfsmount *vfs_create_mount(struct fs_context *fc);
 105extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
 106                                      int flags, const char *name,
 107                                      void *data);
 108extern struct vfsmount *vfs_submount(const struct dentry *mountpoint,
 109                                     struct file_system_type *type,
 110                                     const char *name, void *data);
 111
 112extern void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list);
 113extern void mark_mounts_for_expiry(struct list_head *mounts);
 114
 115extern dev_t name_to_dev_t(const char *name);
 116
 117extern unsigned int sysctl_mount_max;
 118
 119extern bool path_is_mountpoint(const struct path *path);
 120
 121extern void kern_unmount_array(struct vfsmount *mnt[], unsigned int num);
 122
 123#endif /* _LINUX_MOUNT_H */
 124