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 struct user_namespace *mnt_userns;
76 } __randomize_layout;
77
mnt_user_ns(const struct vfsmount * mnt)78 static 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
84 struct file; /* forward dec */
85 struct path;
86
87 extern int mnt_want_write(struct vfsmount *mnt);
88 extern int mnt_want_write_file(struct file *file);
89 extern void mnt_drop_write(struct vfsmount *mnt);
90 extern void mnt_drop_write_file(struct file *file);
91 extern void mntput(struct vfsmount *mnt);
92 extern struct vfsmount *mntget(struct vfsmount *mnt);
93 extern struct vfsmount *mnt_clone_internal(const struct path *path);
94 extern bool __mnt_is_readonly(struct vfsmount *mnt);
95 extern bool mnt_may_suid(struct vfsmount *mnt);
96
97 struct path;
98 extern struct vfsmount *clone_private_mount(const struct path *path);
99 extern int __mnt_want_write(struct vfsmount *);
100 extern void __mnt_drop_write(struct vfsmount *);
101
102 struct file_system_type;
103 extern struct vfsmount *fc_mount(struct fs_context *fc);
104 extern struct vfsmount *vfs_create_mount(struct fs_context *fc);
105 extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
106 int flags, const char *name,
107 void *data);
108 extern struct vfsmount *vfs_submount(const struct dentry *mountpoint,
109 struct file_system_type *type,
110 const char *name, void *data);
111
112 extern void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list);
113 extern void mark_mounts_for_expiry(struct list_head *mounts);
114
115 extern dev_t name_to_dev_t(const char *name);
116
117 extern unsigned int sysctl_mount_max;
118
119 extern bool path_is_mountpoint(const struct path *path);
120
121 extern void kern_unmount_array(struct vfsmount *mnt[], unsigned int num);
122
123 #endif /* _LINUX_MOUNT_H */
124