root/include/linux/mount.h

INCLUDED FROM

   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 
  20 struct super_block;
  21 struct vfsmount;
  22 struct dentry;
  23 struct mnt_namespace;
  24 struct 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 
  34 #define MNT_SHRINKABLE  0x100
  35 #define MNT_WRITE_HOLD  0x200
  36 
  37 #define MNT_SHARED      0x1000  /* if the vfsmount is a shared mount */
  38 #define MNT_UNBINDABLE  0x2000  /* if the vfsmount is a unbindable mount */
  39 /*
  40  * MNT_SHARED_MASK is the set of flags that should be cleared when a
  41  * mount becomes shared.  Currently, this is only the flag that says a
  42  * mount cannot be bind mounted, since this is how we create a mount
  43  * that shares events with another mount.  If you add a new MNT_*
  44  * flag, consider how it interacts with shared mounts.
  45  */
  46 #define MNT_SHARED_MASK (MNT_UNBINDABLE)
  47 #define MNT_USER_SETTABLE_MASK  (MNT_NOSUID | MNT_NODEV | MNT_NOEXEC \
  48                                  | MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME \
  49                                  | MNT_READONLY)
  50 #define MNT_ATIME_MASK (MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME )
  51 
  52 #define MNT_INTERNAL_FLAGS (MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL | \
  53                             MNT_DOOMED | MNT_SYNC_UMOUNT | MNT_MARKED)
  54 
  55 #define MNT_INTERNAL    0x4000
  56 
  57 #define MNT_LOCK_ATIME          0x040000
  58 #define MNT_LOCK_NOEXEC         0x080000
  59 #define MNT_LOCK_NOSUID         0x100000
  60 #define MNT_LOCK_NODEV          0x200000
  61 #define MNT_LOCK_READONLY       0x400000
  62 #define MNT_LOCKED              0x800000
  63 #define MNT_DOOMED              0x1000000
  64 #define MNT_SYNC_UMOUNT         0x2000000
  65 #define MNT_MARKED              0x4000000
  66 #define MNT_UMOUNT              0x8000000
  67 
  68 struct vfsmount {
  69         struct dentry *mnt_root;        /* root of the mounted tree */
  70         struct super_block *mnt_sb;     /* pointer to superblock */
  71         int mnt_flags;
  72 } __randomize_layout;
  73 
  74 struct file; /* forward dec */
  75 struct path;
  76 
  77 extern int mnt_want_write(struct vfsmount *mnt);
  78 extern int mnt_want_write_file(struct file *file);
  79 extern int mnt_clone_write(struct vfsmount *mnt);
  80 extern void mnt_drop_write(struct vfsmount *mnt);
  81 extern void mnt_drop_write_file(struct file *file);
  82 extern void mntput(struct vfsmount *mnt);
  83 extern struct vfsmount *mntget(struct vfsmount *mnt);
  84 extern struct vfsmount *mnt_clone_internal(const struct path *path);
  85 extern bool __mnt_is_readonly(struct vfsmount *mnt);
  86 extern bool mnt_may_suid(struct vfsmount *mnt);
  87 
  88 struct path;
  89 extern struct vfsmount *clone_private_mount(const struct path *path);
  90 extern int __mnt_want_write(struct vfsmount *);
  91 extern void __mnt_drop_write(struct vfsmount *);
  92 
  93 struct file_system_type;
  94 extern struct vfsmount *fc_mount(struct fs_context *fc);
  95 extern struct vfsmount *vfs_create_mount(struct fs_context *fc);
  96 extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
  97                                       int flags, const char *name,
  98                                       void *data);
  99 extern struct vfsmount *vfs_submount(const struct dentry *mountpoint,
 100                                      struct file_system_type *type,
 101                                      const char *name, void *data);
 102 
 103 extern void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list);
 104 extern void mark_mounts_for_expiry(struct list_head *mounts);
 105 
 106 extern dev_t name_to_dev_t(const char *name);
 107 
 108 extern unsigned int sysctl_mount_max;
 109 
 110 extern bool path_is_mountpoint(const struct path *path);
 111 
 112 #endif /* _LINUX_MOUNT_H */