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 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 #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
  71 struct 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 } __randomize_layout;
  76
  77 struct file; /* forward dec */
  78 struct path;
  79
  80 extern int mnt_want_write(struct vfsmount *mnt);
  81 extern int mnt_want_write_file(struct file *file);
  82 extern int mnt_clone_write(struct vfsmount *mnt);
  83 extern void mnt_drop_write(struct vfsmount *mnt);
  84 extern void mnt_drop_write_file(struct file *file);
  85 extern void mntput(struct vfsmount *mnt);
  86 extern struct vfsmount *mntget(struct vfsmount *mnt);
  87 extern struct vfsmount *mnt_clone_internal(const struct path *path);
  88 extern bool __mnt_is_readonly(struct vfsmount *mnt);
  89 extern bool mnt_may_suid(struct vfsmount *mnt);
  90
  91 struct path;
  92 extern struct vfsmount *clone_private_mount(const struct path *path);
  93 extern int __mnt_want_write(struct vfsmount *);
  94 extern void __mnt_drop_write(struct vfsmount *);
  95
  96 struct file_system_type;
  97 extern struct vfsmount *fc_mount(struct fs_context *fc);
  98 extern struct vfsmount *vfs_create_mount(struct fs_context *fc);
  99 extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
 100                                       int flags, const char *name,
 101                                       void *data);
 102 extern struct vfsmount *vfs_submount(const struct dentry *mountpoint,
 103                                      struct file_system_type *type,
 104                                      const char *name, void *data);
 105
 106 extern void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list);
 107 extern void mark_mounts_for_expiry(struct list_head *mounts);
 108
 109 extern dev_t name_to_dev_t(const char *name);
 110
 111 extern unsigned int sysctl_mount_max;
 112
 113 extern bool path_is_mountpoint(const struct path *path);
 114
 115 extern void kern_unmount_array(struct vfsmount *mnt[], unsigned int num);
 116
 117 #endif /* _LINUX_MOUNT_H */