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