Merge branch 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jlbec...
[linux-2.6] / drivers / xen / xenfs / super.c
1 /*
2  *  xenfs.c - a filesystem for passing info between the a domain and
3  *  the hypervisor.
4  *
5  * 2008-10-07  Alex Zeffertt    Replaced /proc/xen/xenbus with xenfs filesystem
6  *                              and /proc/xen compatibility mount point.
7  *                              Turned xenfs into a loadable module.
8  */
9
10 #include <linux/kernel.h>
11 #include <linux/errno.h>
12 #include <linux/module.h>
13 #include <linux/fs.h>
14 #include <linux/magic.h>
15
16 #include "xenfs.h"
17
18 #include <asm/xen/hypervisor.h>
19
20 MODULE_DESCRIPTION("Xen filesystem");
21 MODULE_LICENSE("GPL");
22
23 static ssize_t capabilities_read(struct file *file, char __user *buf,
24                                  size_t size, loff_t *off)
25 {
26         char *tmp = "";
27
28         if (xen_initial_domain())
29                 tmp = "control_d\n";
30
31         return simple_read_from_buffer(buf, size, off, tmp, strlen(tmp));
32 }
33
34 static const struct file_operations capabilities_file_ops = {
35         .read = capabilities_read,
36 };
37
38 static int xenfs_fill_super(struct super_block *sb, void *data, int silent)
39 {
40         static struct tree_descr xenfs_files[] = {
41                 [1] = {},
42                 { "xenbus", &xenbus_file_ops, S_IRUSR|S_IWUSR },
43                 { "capabilities", &capabilities_file_ops, S_IRUGO },
44                 {""},
45         };
46
47         return simple_fill_super(sb, XENFS_SUPER_MAGIC, xenfs_files);
48 }
49
50 static int xenfs_get_sb(struct file_system_type *fs_type,
51                         int flags, const char *dev_name,
52                         void *data, struct vfsmount *mnt)
53 {
54         return get_sb_single(fs_type, flags, data, xenfs_fill_super, mnt);
55 }
56
57 static struct file_system_type xenfs_type = {
58         .owner =        THIS_MODULE,
59         .name =         "xenfs",
60         .get_sb =       xenfs_get_sb,
61         .kill_sb =      kill_litter_super,
62 };
63
64 static int __init xenfs_init(void)
65 {
66         if (xen_pv_domain())
67                 return register_filesystem(&xenfs_type);
68
69         printk(KERN_INFO "XENFS: not registering filesystem on non-xen platform\n");
70         return 0;
71 }
72
73 static void __exit xenfs_exit(void)
74 {
75         if (xen_pv_domain())
76                 unregister_filesystem(&xenfs_type);
77 }
78
79 module_init(xenfs_init);
80 module_exit(xenfs_exit);
81