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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#define MNT_STRICTATIME 0x80
31
32#define MNT_SHRINKABLE 0x100
33#define MNT_WRITE_HOLD 0x200
34
35#define MNT_SHARED 0x1000 /* if the vfsmount is a shared mount */
36#define MNT_UNBINDABLE 0x2000 /* if the vfsmount is a unbindable mount */
37/*
38 * MNT_SHARED_MASK is the set of flags that should be cleared when a
39 * mount becomes shared. Currently, this is only the flag that says a
40 * mount cannot be bind mounted, since this is how we create a mount
41 * that shares events with another mount. If you add a new MNT_*
42 * flag, consider how it interacts with shared mounts.
43 */
44#define MNT_SHARED_MASK (MNT_UNBINDABLE)
45#define MNT_PROPAGATION_MASK (MNT_SHARED | MNT_UNBINDABLE)
46
47
48#define MNT_INTERNAL 0x4000
49
50struct vfsmount {
51 struct list_head mnt_hash;
52 struct vfsmount *mnt_parent; /* fs we are mounted on */
53 struct dentry *mnt_mountpoint; /* dentry of mountpoint */
54 struct dentry *mnt_root; /* root of the mounted tree */
55 struct super_block *mnt_sb; /* pointer to superblock */
56 struct list_head mnt_mounts; /* list of children, anchored here */
57 struct list_head mnt_child; /* and going through their mnt_child */
58 int mnt_flags;
59 /* 4 bytes hole on 64bits arches */
60 const char *mnt_devname; /* Name of device e.g. /dev/dsk/hda1 */
61 struct list_head mnt_list;
62 struct list_head mnt_expire; /* link in fs-specific expiry list */
63 struct list_head mnt_share; /* circular list of shared mounts */
64 struct list_head mnt_slave_list;/* list of slave mounts */
65 struct list_head mnt_slave; /* slave list entry */
66 struct vfsmount *mnt_master; /* slave is on master->mnt_slave_list */
67 struct mnt_namespace *mnt_ns; /* containing namespace */
68 int mnt_id; /* mount identifier */
69 int mnt_group_id; /* peer group identifier */
70 /*
71 * We put mnt_count & mnt_expiry_mark at the end of struct vfsmount
72 * to let these frequently modified fields in a separate cache line
73 * (so that reads of mnt_flags wont ping-pong on SMP machines)
74 */
75 atomic_t mnt_count;
76 int mnt_expiry_mark; /* true if marked for expiry */
77 int mnt_pinned;
78 int mnt_ghosts;
79#ifdef CONFIG_SMP
80 int __percpu *mnt_writers;
81#else
82 int mnt_writers;
83#endif
84};
85
86static inline int *get_mnt_writers_ptr(struct vfsmount *mnt)
87{
88#ifdef CONFIG_SMP
89 return mnt->mnt_writers;
90#else
91 return &mnt->mnt_writers;
92#endif
93}
94
95static inline struct vfsmount *mntget(struct vfsmount *mnt)
96{
97 if (mnt)
98 atomic_inc(&mnt->mnt_count);
99 return mnt;
100}
101
102struct file; /* forward dec */
103
104extern int mnt_want_write(struct vfsmount *mnt);
105extern int mnt_want_write_file(struct file *file);
106extern int mnt_clone_write(struct vfsmount *mnt);
107extern void mnt_drop_write(struct vfsmount *mnt);
108extern void mntput_no_expire(struct vfsmount *mnt);
109extern void mnt_pin(struct vfsmount *mnt);
110extern void mnt_unpin(struct vfsmount *mnt);
111extern int __mnt_is_readonly(struct vfsmount *mnt);
112
113static inline void mntput(struct vfsmount *mnt)
114{
115 if (mnt) {
116 mnt->mnt_expiry_mark = 0;
117 mntput_no_expire(mnt);
118 }
119}
120
121extern struct vfsmount *do_kern_mount(const char *fstype, int flags,
122 const char *name, void *data);
123
124struct file_system_type;
125extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
126 int flags, const char *name,
127 void *data);
128
129struct nameidata;
130
131struct path;
132extern int do_add_mount(struct vfsmount *newmnt, struct path *path,
133 int mnt_flags, struct list_head *fslist);
134
135extern void mark_mounts_for_expiry(struct list_head *mounts);
136
137extern dev_t name_to_dev_t(char *name);
138
139#endif /* _LINUX_MOUNT_H */