LXR linux/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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11
  12#include <linux/kernel.h>
  13#include <linux/errno.h>
  14#include <linux/module.h>
  15#include <linux/fs.h>
  16#include <linux/magic.h>
  17
  18#include <xen/xen.h>
  19
  20#include "xenfs.h"
  21#include "../privcmd.h"
  22#include "../xenbus/xenbus_comms.h"
  23
  24#include <asm/xen/hypervisor.h>
  25
  26MODULE_DESCRIPTION("Xen filesystem");
  27MODULE_LICENSE("GPL");
  28
  29static ssize_t capabilities_read(struct file *file, char __user *buf,
  30                                 size_t size, loff_t *off)
  31{
  32        char *tmp = "";
  33
  34        if (xen_initial_domain())
  35                tmp = "control_d\n";
  36
  37        return simple_read_from_buffer(buf, size, off, tmp, strlen(tmp));
  38}
  39
  40static const struct file_operations capabilities_file_ops = {
  41        .read = capabilities_read,
  42        .llseek = default_llseek,
  43};
  44
  45static int xenfs_fill_super(struct super_block *sb, void *data, int silent)
  46{
  47        static struct tree_descr xenfs_files[] = {
  48                [2] = { "xenbus", &xen_xenbus_fops, S_IRUSR|S_IWUSR },
  49                { "capabilities", &capabilities_file_ops, S_IRUGO },
  50                { "privcmd", &xen_privcmd_fops, S_IRUSR|S_IWUSR },
  51                {""},
  52        };
  53
  54        static struct tree_descr xenfs_init_files[] = {
  55                [2] = { "xenbus", &xen_xenbus_fops, S_IRUSR|S_IWUSR },
  56                { "capabilities", &capabilities_file_ops, S_IRUGO },
  57                { "privcmd", &xen_privcmd_fops, S_IRUSR|S_IWUSR },
  58                { "xsd_kva", &xsd_kva_file_ops, S_IRUSR|S_IWUSR},
  59                { "xsd_port", &xsd_port_file_ops, S_IRUSR|S_IWUSR},
  60#ifdef CONFIG_XEN_SYMS
  61                { "xensyms", &xensyms_ops, S_IRUSR},
  62#endif
  63                {""},
  64        };
  65
  66        return simple_fill_super(sb, XENFS_SUPER_MAGIC,
  67                        xen_initial_domain() ? xenfs_init_files : xenfs_files);
  68}
  69
  70static struct dentry *xenfs_mount(struct file_system_type *fs_type,
  71                                  int flags, const char *dev_name,
  72                                  void *data)
  73{
  74        return mount_single(fs_type, flags, data, xenfs_fill_super);
  75}
  76
  77static struct file_system_type xenfs_type = {
  78        .owner =        THIS_MODULE,
  79        .name =         "xenfs",
  80        .mount =        xenfs_mount,
  81        .kill_sb =      kill_litter_super,
  82};
  83MODULE_ALIAS_FS("xenfs");
  84
  85static int __init xenfs_init(void)
  86{
  87        if (xen_domain())
  88                return register_filesystem(&xenfs_type);
  89
  90        pr_info("not registering filesystem on non-xen platform\n");
  91        return 0;
  92}
  93
  94static void __exit xenfs_exit(void)
  95{
  96        if (xen_domain())
  97                unregister_filesystem(&xenfs_type);
  98}
  99
 100module_init(xenfs_init);
 101module_exit(xenfs_exit);
 102
 103