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1/*
2 *
3 * Definitions for mount interface. This describes the in the kernel build
4 * linkedlist with mounted filesystems.
5 *
6 * Author: Marco van Wieringen <mvw@planets.elm.net>
7 *
8 */
9#ifndef _LINUX_MOUNT_H
10#define _LINUX_MOUNT_H
11
12#include <linux/types.h>
13#include <linux/list.h>
14#include <linux/nodemask.h>
15#include <linux/spinlock.h>
16#include <asm/atomic.h>
17
18struct super_block;
19struct vfsmount;
20struct dentry;
21struct mnt_namespace;
22
23#define MNT_NOSUID 0x01
24#define MNT_NODEV 0x02
25#define MNT_NOEXEC 0x04
26#define MNT_NOATIME 0x08
27#define MNT_NODIRATIME 0x10
28#define MNT_RELATIME 0x20
29#define MNT_READONLY 0x40 /* does the user want this to be r/o? */
30
31#define MNT_SHRINKABLE 0x100
32#define MNT_WRITE_HOLD 0x200
33
34#define MNT_SHARED 0x1000 /* if the vfsmount is a shared mount */
35#define MNT_UNBINDABLE 0x2000 /* if the vfsmount is a unbindable mount */
36/*
37 * MNT_SHARED_MASK is the set of flags that should be cleared when a
38 * mount becomes shared. Currently, this is only the flag that says a
39 * mount cannot be bind mounted, since this is how we create a mount
40 * that shares events with another mount. If you add a new MNT_*
41 * flag, consider how it interacts with shared mounts.
42 */
43#define MNT_SHARED_MASK (MNT_UNBINDABLE)
44#define MNT_PROPAGATION_MASK (MNT_SHARED | MNT_UNBINDABLE)
45
46
47#define MNT_INTERNAL 0x4000
48
49struct vfsmount {
50 struct list_head mnt_hash;
51 struct vfsmount *mnt_parent; /* fs we are mounted on */
52 struct dentry *mnt_mountpoint; /* dentry of mountpoint */
53 struct dentry *mnt_root; /* root of the mounted tree */
54 struct super_block *mnt_sb; /* pointer to superblock */
55 struct list_head mnt_mounts; /* list of children, anchored here */
56 struct list_head mnt_child; /* and going through their mnt_child */
57 int mnt_flags;
58 /* 4 bytes hole on 64bits arches without fsnotify */
59#ifdef CONFIG_FSNOTIFY
60 __u32 mnt_fsnotify_mask;
61 struct hlist_head mnt_fsnotify_marks;
62#endif
63 const char *mnt_devname; /* Name of device e.g. /dev/dsk/hda1 */
64 struct list_head mnt_list;
65 struct list_head mnt_expire; /* link in fs-specific expiry list */
66 struct list_head mnt_share; /* circular list of shared mounts */
67 struct list_head mnt_slave_list;/* list of slave mounts */
68 struct list_head mnt_slave; /* slave list entry */
69 struct vfsmount *mnt_master; /* slave is on master->mnt_slave_list */
70 struct mnt_namespace *mnt_ns; /* containing namespace */
71 int mnt_id; /* mount identifier */
72 int mnt_group_id; /* peer group identifier */
73 /*
74 * We put mnt_count & mnt_expiry_mark at the end of struct vfsmount
75 * to let these frequently modified fields in a separate cache line
76 * (so that reads of mnt_flags wont ping-pong on SMP machines)
77 */
78 atomic_t mnt_count;
79 int mnt_expiry_mark; /* true if marked for expiry */
80 int mnt_pinned;
81 int mnt_ghosts;
82#ifdef CONFIG_SMP
83 int __percpu *mnt_writers;
84#else
85 int mnt_writers;
86#endif
87};
88
89static inline int *get_mnt_writers_ptr(struct vfsmount *mnt)
90{
91#ifdef CONFIG_SMP
92 return mnt->mnt_writers;
93#else
94 return &mnt->mnt_writers;
95#endif
96}
97
98static inline struct vfsmount *mntget(struct vfsmount *mnt)
99{
100 if (mnt)
101 atomic_inc(&mnt->mnt_count);
102 return mnt;
103}
104
105struct file; /* forward dec */
106
107extern int mnt_want_write(struct vfsmount *mnt);
108extern int mnt_want_write_file(struct file *file);
109extern int mnt_clone_write(struct vfsmount *mnt);
110extern void mnt_drop_write(struct vfsmount *mnt);
111extern void mntput_no_expire(struct vfsmount *mnt);
112extern void mnt_pin(struct vfsmount *mnt);
113extern void mnt_unpin(struct vfsmount *mnt);
114extern int __mnt_is_readonly(struct vfsmount *mnt);
115
116static inline void mntput(struct vfsmount *mnt)
117{
118 if (mnt) {
119 mnt->mnt_expiry_mark = 0;
120 mntput_no_expire(mnt);
121 }
122}
123
124extern struct vfsmount *do_kern_mount(const char *fstype, int flags,
125 const char *name, void *data);
126
127struct file_system_type;
128extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
129 int flags, const char *name,
130 void *data);
131
132struct nameidata;
133
134struct path;
135extern int do_add_mount(struct vfsmount *newmnt, struct path *path,
136 int mnt_flags, struct list_head *fslist);
137
138extern void mark_mounts_for_expiry(struct list_head *mounts);
139
140extern dev_t name_to_dev_t(char *name);
141
142#endif /* _LINUX_MOUNT_H */