2 * xenfs.c - a filesystem for passing info between the a domain and
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.
10 #include <linux/kernel.h>
11 #include <linux/errno.h>
12 #include <linux/module.h>
14 #include <linux/magic.h>
16 #include <linux/backing-dev.h>
22 #include <asm/xen/hypervisor.h>
24 MODULE_DESCRIPTION("Xen filesystem");
25 MODULE_LICENSE("GPL");
27 static int xenfs_set_page_dirty(struct page *page)
29 return !TestSetPageDirty(page);
32 static const struct address_space_operations xenfs_aops = {
33 .set_page_dirty = xenfs_set_page_dirty,
36 static struct backing_dev_info xenfs_backing_dev_info = {
37 .ra_pages = 0, /* No readahead */
38 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
41 static struct inode *xenfs_make_inode(struct super_block *sb, int mode)
43 struct inode *ret = new_inode(sb);
47 ret->i_mapping->a_ops = &xenfs_aops;
48 ret->i_mapping->backing_dev_info = &xenfs_backing_dev_info;
49 ret->i_uid = ret->i_gid = 0;
51 ret->i_atime = ret->i_mtime = ret->i_ctime = CURRENT_TIME;
56 static struct dentry *xenfs_create_file(struct super_block *sb,
57 struct dentry *parent,
59 const struct file_operations *fops,
63 struct dentry *dentry;
66 dentry = d_alloc_name(parent, name);
70 inode = xenfs_make_inode(sb, S_IFREG | mode);
77 inode->i_private = data;
83 static ssize_t capabilities_read(struct file *file, char __user *buf,
84 size_t size, loff_t *off)
88 if (xen_initial_domain())
91 return simple_read_from_buffer(buf, size, off, tmp, strlen(tmp));
94 static const struct file_operations capabilities_file_ops = {
95 .read = capabilities_read,
96 .llseek = default_llseek,
99 static int xenfs_fill_super(struct super_block *sb, void *data, int silent)
101 static struct tree_descr xenfs_files[] = {
103 { "xenbus", &xenbus_file_ops, S_IRUSR|S_IWUSR },
104 { "capabilities", &capabilities_file_ops, S_IRUGO },
105 { "privcmd", &privcmd_file_ops, S_IRUSR|S_IWUSR },
110 rc = simple_fill_super(sb, XENFS_SUPER_MAGIC, xenfs_files);
114 if (xen_initial_domain()) {
115 xenfs_create_file(sb, sb->s_root, "xsd_kva",
116 &xsd_kva_file_ops, NULL, S_IRUSR|S_IWUSR);
117 xenfs_create_file(sb, sb->s_root, "xsd_port",
118 &xsd_port_file_ops, NULL, S_IRUSR|S_IWUSR);
124 static int xenfs_mount(struct file_system_type *fs_type,
125 int flags, const char *dev_name,
128 return mount_single(fs_type, flags, data, xenfs_fill_super);
131 static struct file_system_type xenfs_type = {
132 .owner = THIS_MODULE,
134 .mount = xenfs_mount,
135 .kill_sb = kill_litter_super,
138 static int __init xenfs_init(void)
142 printk(KERN_INFO "xenfs: not registering filesystem on non-xen platform\n");
146 err = register_filesystem(&xenfs_type);
148 printk(KERN_ERR "xenfs: Unable to register filesystem!\n");
152 err = bdi_init(&xenfs_backing_dev_info);
154 unregister_filesystem(&xenfs_type);
161 static void __exit xenfs_exit(void)
164 unregister_filesystem(&xenfs_type);
167 module_init(xenfs_init);
168 module_exit(xenfs_exit);