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 <xen/xen.h>
  17
  18 #include "xenfs.h"
  19 #include "../privcmd.h"
  20 #include "../xenbus/xenbus_comms.h"
  21
  22 #include <asm/xen/hypervisor.h>
  23
  24 MODULE_DESCRIPTION("Xen filesystem");
  25 MODULE_LICENSE("GPL");
  26
  27 static ssize_t capabilities_read(struct file *file, char __user *buf,
  28                                  size_t size, loff_t *off)
  29 {
  30         char *tmp = "";
  31
  32         if (xen_initial_domain())
  33                 tmp = "control_d\n";
  34
  35         return simple_read_from_buffer(buf, size, off, tmp, strlen(tmp));
  36 }
  37
  38 static const struct file_operations capabilities_file_ops = {
  39         .read = capabilities_read,
  40         .llseek = default_llseek,
  41 };
  42
  43 static int xenfs_fill_super(struct super_block *sb, void *data, int silent)
  44 {
  45         static struct tree_descr xenfs_files[] = {
  46                 [2] = { "xenbus", &xen_xenbus_fops, S_IRUSR|S_IWUSR },
  47                 { "capabilities", &capabilities_file_ops, S_IRUGO },
  48                 { "privcmd", &xen_privcmd_fops, S_IRUSR|S_IWUSR },
  49                 {""},
  50         };
  51
  52         static struct tree_descr xenfs_init_files[] = {
  53                 [2] = { "xenbus", &xen_xenbus_fops, S_IRUSR|S_IWUSR },
  54                 { "capabilities", &capabilities_file_ops, S_IRUGO },
  55                 { "privcmd", &xen_privcmd_fops, S_IRUSR|S_IWUSR },
  56                 { "xsd_kva", &xsd_kva_file_ops, S_IRUSR|S_IWUSR},
  57                 { "xsd_port", &xsd_port_file_ops, S_IRUSR|S_IWUSR},
  58                 {""},
  59         };
  60
  61         return simple_fill_super(sb, XENFS_SUPER_MAGIC,
  62                         xen_initial_domain() ? xenfs_init_files : xenfs_files);
  63 }
  64
  65 static struct dentry *xenfs_mount(struct file_system_type *fs_type,
  66                                   int flags, const char *dev_name,
  67                                   void *data)
  68 {
  69         return mount_single(fs_type, flags, data, xenfs_fill_super);
  70 }
  71
  72 static struct file_system_type xenfs_type = {
  73         .owner =        THIS_MODULE,
  74         .name =         "xenfs",
  75         .mount =        xenfs_mount,
  76         .kill_sb =      kill_litter_super,
  77 };
  78
  79 static int __init xenfs_init(void)
  80 {
  81         if (xen_domain())
  82                 return register_filesystem(&xenfs_type);
  83
  84         printk(KERN_INFO "XENFS: not registering filesystem on non-xen platform\n");
  85         return 0;
  86 }
  87
  88 static void __exit xenfs_exit(void)
  89 {
  90         if (xen_domain())
  91                 unregister_filesystem(&xenfs_type);
  92 }
  93
  94 module_init(xenfs_init);
  95 module_exit(xenfs_exit);
  96