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