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/*
* xenfs.c - a filesystem for passing info between the a domain and
* the hypervisor.
*
* 2008-10-07 Alex Zeffertt Replaced /proc/xen/xenbus with xenfs filesystem
* and /proc/xen compatibility mount point.
* Turned xenfs into a loadable module.
*/
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/magic.h>
#include <linux/mm.h>
#include <linux/backing-dev.h>
#include <xen/xen.h>
#include "xenfs.h"
#include <asm/xen/hypervisor.h>
MODULE_DESCRIPTION("Xen filesystem");
MODULE_LICENSE("GPL");
static int xenfs_set_page_dirty(struct page *page)
{
return !TestSetPageDirty(page);
}
static const struct address_space_operations xenfs_aops = {
.set_page_dirty = xenfs_set_page_dirty,
};
static struct backing_dev_info xenfs_backing_dev_info = {
.ra_pages = 0, /* No readahead */
.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
};
static struct inode *xenfs_make_inode(struct super_block *sb, int mode)
{
struct inode *ret = new_inode(sb);
if (ret) {
ret->i_mode = mode;
ret->i_mapping->a_ops = &xenfs_aops;
ret->i_mapping->backing_dev_info = &xenfs_backing_dev_info;
ret->i_uid = ret->i_gid = 0;
ret->i_blocks = 0;
ret->i_atime = ret->i_mtime = ret->i_ctime = CURRENT_TIME;
}
return ret;
}
static struct dentry *xenfs_create_file(struct super_block *sb,
struct dentry *parent,
const char *name,
const struct file_operations *fops,
void *data,
int mode)
{
struct dentry *dentry;
struct inode *inode;
dentry = d_alloc_name(parent, name);
if (!dentry)
return NULL;
inode = xenfs_make_inode(sb, S_IFREG | mode);
if (!inode) {
dput(dentry);
return NULL;
}
inode->i_fop = fops;
inode->i_private = data;
d_add(dentry, inode);
return dentry;
}
static ssize_t capabilities_read(struct file *file, char __user *buf,
size_t size, loff_t *off)
{
char *tmp = "";
if (xen_initial_domain())
tmp = "control_d\n";
return simple_read_from_buffer(buf, size, off, tmp, strlen(tmp));
}
static const struct file_operations capabilities_file_ops = {
.read = capabilities_read,
.llseek = default_llseek,
};
static int xenfs_fill_super(struct super_block *sb, void *data, int silent)
{
static struct tree_descr xenfs_files[] = {
[1] = {},
{ "xenbus", &xenbus_file_ops, S_IRUSR|S_IWUSR },
{ "capabilities", &capabilities_file_ops, S_IRUGO },
{ "privcmd", &privcmd_file_ops, S_IRUSR|S_IWUSR },
{""},
};
int rc;
rc = simple_fill_super(sb, XENFS_SUPER_MAGIC, xenfs_files);
if (rc < 0)
return rc;
if (xen_initial_domain()) {
xenfs_create_file(sb, sb->s_root, "xsd_kva",
&xsd_kva_file_ops, NULL, S_IRUSR|S_IWUSR);
xenfs_create_file(sb, sb->s_root, "xsd_port",
&xsd_port_file_ops, NULL, S_IRUSR|S_IWUSR);
}
return rc;
}
static struct dentry *xenfs_mount(struct file_system_type *fs_type,
int flags, const char *dev_name,
void *data)
{
return mount_single(fs_type, flags, data, xenfs_fill_super);
}
static struct file_system_type xenfs_type = {
.owner = THIS_MODULE,
.name = "xenfs",
.mount = xenfs_mount,
.kill_sb = kill_litter_super,
};
static int __init xenfs_init(void)
{
int err;
if (!xen_domain()) {
printk(KERN_INFO "xenfs: not registering filesystem on non-xen platform\n");
return 0;
}
err = register_filesystem(&xenfs_type);
if (err) {
printk(KERN_ERR "xenfs: Unable to register filesystem!\n");
goto out;
}
err = bdi_init(&xenfs_backing_dev_info);
if (err)
unregister_filesystem(&xenfs_type);
out:
return err;
}
static void __exit xenfs_exit(void)
{
if (xen_domain())
unregister_filesystem(&xenfs_type);
}
module_init(xenfs_init);
module_exit(xenfs_exit);
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