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 <xen/xen.h> 17 18#include "xenfs.h" 19 20#include <asm/xen/hypervisor.h> 21 22MODULE_DESCRIPTION("Xen filesystem"); 23MODULE_LICENSE("GPL"); 24 25static ssize_t capabilities_read(struct file *file, char __user *buf, 26 size_t size, loff_t *off) 27{ 28 char *tmp = ""; 29 30 if (xen_initial_domain()) 31 tmp = "control_d\n"; 32 33 return simple_read_from_buffer(buf, size, off, tmp, strlen(tmp)); 34} 35 36static const struct file_operations capabilities_file_ops = { 37 .read = capabilities_read, 38}; 39 40static int xenfs_fill_super(struct super_block *sb, void *data, int silent) 41{ 42 static struct tree_descr xenfs_files[] = { 43 [1] = {}, 44 { "xenbus", &xenbus_file_ops, S_IRUSR|S_IWUSR }, 45 { "capabilities", &capabilities_file_ops, S_IRUGO }, 46 {""}, 47 }; 48 49 return simple_fill_super(sb, XENFS_SUPER_MAGIC, xenfs_files); 50} 51 52static int xenfs_get_sb(struct file_system_type *fs_type, 53 int flags, const char *dev_name, 54 void *data, struct vfsmount *mnt) 55{ 56 return get_sb_single(fs_type, flags, data, xenfs_fill_super, mnt); 57} 58 59static struct file_system_type xenfs_type = { 60 .owner = THIS_MODULE, 61 .name = "xenfs", 62 .get_sb = xenfs_get_sb, 63 .kill_sb = kill_litter_super, 64}; 65 66static int __init xenfs_init(void) 67{ 68 if (xen_domain()) 69 return register_filesystem(&xenfs_type); 70 71 printk(KERN_INFO "XENFS: not registering filesystem on non-xen platform\n"); 72 return 0; 73} 74 75static void __exit xenfs_exit(void) 76{ 77 if (xen_domain()) 78 unregister_filesystem(&xenfs_type); 79} 80 81module_init(xenfs_init); 82module_exit(xenfs_exit); 83