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 */
110