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
  20 struct super_block;
  21 struct vfsmount;
  22 struct dentry;
  23 struct mnt_namespace;
  24
  25 #define MNT_NOSUID      0x01
  26 #define MNT_NODEV       0x02
  27 #define MNT_NOEXEC      0x04
  28 #define MNT_NOATIME     0x08
  29 #define MNT_NODIRATIME  0x10
  30 #define MNT_RELATIME    0x20
  31 #define MNT_READONLY    0x40    /* does the user want this to be r/o? */
  32
  33 #define MNT_SHRINKABLE  0x100
  34 #define MNT_WRITE_HOLD  0x200
  35
  36 #define MNT_SHARED      0x1000  /* if the vfsmount is a shared mount */
  37 #define MNT_UNBINDABLE  0x2000  /* if the vfsmount is a unbindable mount */
  38 /*
  39  * MNT_SHARED_MASK is the set of flags that should be cleared when a
  40  * mount becomes shared.  Currently, this is only the flag that says a
  41  * mount cannot be bind mounted, since this is how we create a mount
  42  * that shares events with another mount.  If you add a new MNT_*
  43  * flag, consider how it interacts with shared mounts.
  44  */
  45 #define MNT_SHARED_MASK (MNT_UNBINDABLE)
  46 #define MNT_USER_SETTABLE_MASK  (MNT_NOSUID | MNT_NODEV | MNT_NOEXEC \
  47                                  | MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME \
  48                                  | MNT_READONLY)
  49 #define MNT_ATIME_MASK (MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME )
  50
  51 #define MNT_INTERNAL_FLAGS (MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL | \
  52                             MNT_DOOMED | MNT_SYNC_UMOUNT | MNT_MARKED)
  53
  54 #define MNT_INTERNAL    0x4000
  55
  56 #define MNT_LOCK_ATIME          0x040000
  57 #define MNT_LOCK_NOEXEC         0x080000
  58 #define MNT_LOCK_NOSUID         0x100000
  59 #define MNT_LOCK_NODEV          0x200000
  60 #define MNT_LOCK_READONLY       0x400000
  61 #define MNT_LOCKED              0x800000
  62 #define MNT_DOOMED              0x1000000
  63 #define MNT_SYNC_UMOUNT         0x2000000
  64 #define MNT_MARKED              0x4000000
  65 #define MNT_UMOUNT              0x8000000
  66
  67 struct vfsmount {
  68         struct dentry *mnt_root;        /* root of the mounted tree */
  69         struct super_block *mnt_sb;     /* pointer to superblock */
  70         int mnt_flags;
  71 } __randomize_layout;
  72
  73 struct file; /* forward dec */
  74 struct path;
  75
  76 extern int mnt_want_write(struct vfsmount *mnt);
  77 extern int mnt_want_write_file(struct file *file);
  78 extern int mnt_clone_write(struct vfsmount *mnt);
  79 extern void mnt_drop_write(struct vfsmount *mnt);
  80 extern void mnt_drop_write_file(struct file *file);
  81 extern void mntput(struct vfsmount *mnt);
  82 extern struct vfsmount *mntget(struct vfsmount *mnt);
  83 extern struct vfsmount *mnt_clone_internal(const struct path *path);
  84 extern int __mnt_is_readonly(struct vfsmount *mnt);
  85 extern bool mnt_may_suid(struct vfsmount *mnt);
  86
  87 struct path;
  88 extern struct vfsmount *clone_private_mount(const struct path *path);
  89 extern int __mnt_want_write(struct vfsmount *);
  90 extern void __mnt_drop_write(struct vfsmount *);
  91
  92 struct file_system_type;
  93 extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
  94                                       int flags, const char *name,
  95                                       void *data);
  96 extern struct vfsmount *vfs_submount(const struct dentry *mountpoint,
  97                                      struct file_system_type *type,
  98                                      const char *name, void *data);
  99
 100 extern void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list);
 101 extern void mark_mounts_for_expiry(struct list_head *mounts);
 102
 103 extern dev_t name_to_dev_t(const char *name);
 104
 105 extern unsigned int sysctl_mount_max;
 106
 107 extern bool path_is_mountpoint(const struct path *path);
 108
 109 #endif /* _LINUX_MOUNT_H */