1 files changed, 1045 insertions, 0 deletions

diff --git a/fs/hostfs/hostfs_kern.c b/fs/hostfs/hostfs_kern.c
new file mode 100644
index 000000000000..a88ad2924851
--- /dev/null
+++ b/fs/hostfs/hostfs_kern.c
@@ -0,0 +1,1045 @@
+/*
+ * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
+ * Licensed under the GPL
+ *
+ * Ported the filesystem routines to 2.5.
+ * 2003-02-10 Petr Baudis <pasky@ucw.cz>
+ */
+
+#include <linux/stddef.h>
+#include <linux/fs.h>
+#include <linux/version.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/pagemap.h>
+#include <linux/blkdev.h>
+#include <linux/list.h>
+#include <linux/root_dev.h>
+#include <linux/statfs.h>
+#include <linux/kdev_t.h>
+#include <asm/uaccess.h>
+#include "hostfs.h"
+#include "kern_util.h"
+#include "kern.h"
+#include "user_util.h"
+#include "2_5compat.h"
+#include "init.h"
+
+struct hostfs_inode_info {
+	char *host_filename;
+	int fd;
+	int mode;
+	struct inode vfs_inode;
+};
+
+static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode)
+{
+	return(list_entry(inode, struct hostfs_inode_info, vfs_inode));
+}
+
+#define FILE_HOSTFS_I(file) HOSTFS_I((file)->f_dentry->d_inode)
+
+int hostfs_d_delete(struct dentry *dentry)
+{
+	return(1);
+}
+
+struct dentry_operations hostfs_dentry_ops = {
+	.d_delete		= hostfs_d_delete,
+};
+
+/* Changed in hostfs_args before the kernel starts running */
+static char *root_ino = "/";
+static int append = 0;
+
+#define HOSTFS_SUPER_MAGIC 0x00c0ffee
+
+static struct inode_operations hostfs_iops;
+static struct inode_operations hostfs_dir_iops;
+static struct address_space_operations hostfs_link_aops;
+
+#ifndef MODULE
+static int __init hostfs_args(char *options, int *add)
+{
+	char *ptr;
+
+	ptr = strchr(options, ',');
+	if(ptr != NULL)
+		*ptr++ = '\0';
+	if(*options != '\0')
+		root_ino = options;
+
+	options = ptr;
+	while(options){
+		ptr = strchr(options, ',');
+		if(ptr != NULL)
+			*ptr++ = '\0';
+		if(*options != '\0'){
+			if(!strcmp(options, "append"))
+				append = 1;
+			else printf("hostfs_args - unsupported option - %s\n",
+				    options);
+		}
+		options = ptr;
+	}
+	return(0);
+}
+
+__uml_setup("hostfs=", hostfs_args,
+"hostfs=<root dir>,<flags>,...\n"
+"    This is used to set hostfs parameters.  The root directory argument\n"
+"    is used to confine all hostfs mounts to within the specified directory\n"
+"    tree on the host.  If this isn't specified, then a user inside UML can\n"
+"    mount anything on the host that's accessible to the user that's running\n"
+"    it.\n"
+"    The only flag currently supported is 'append', which specifies that all\n"
+"    files opened by hostfs will be opened in append mode.\n\n"
+);
+#endif
+
+static char *dentry_name(struct dentry *dentry, int extra)
+{
+	struct dentry *parent;
+	char *root, *name;
+	int len;
+
+	len = 0;
+	parent = dentry;
+	while(parent->d_parent != parent){
+		len += parent->d_name.len + 1;
+		parent = parent->d_parent;
+	}
+
+	root = HOSTFS_I(parent->d_inode)->host_filename;
+	len += strlen(root);
+	name = kmalloc(len + extra + 1, GFP_KERNEL);
+	if(name == NULL) return(NULL);
+
+	name[len] = '\0';
+	parent = dentry;
+	while(parent->d_parent != parent){
+		len -= parent->d_name.len + 1;
+		name[len] = '/';
+		strncpy(&name[len + 1], parent->d_name.name,
+			parent->d_name.len);
+		parent = parent->d_parent;
+	}
+	strncpy(name, root, strlen(root));
+	return(name);
+}
+
+static char *inode_name(struct inode *ino, int extra)
+{
+	struct dentry *dentry;
+
+	dentry = list_entry(ino->i_dentry.next, struct dentry, d_alias);
+	return(dentry_name(dentry, extra));
+}
+
+static int read_name(struct inode *ino, char *name)
+{
+	/* The non-int inode fields are copied into ints by stat_file and
+	 * then copied into the inode because passing the actual pointers
+	 * in and having them treated as int * breaks on big-endian machines
+	 */
+	int err;
+	int i_mode, i_nlink, i_blksize;
+	unsigned long long i_size;
+	unsigned long long i_ino;
+	unsigned long long i_blocks;
+
+	err = stat_file(name, &i_ino, &i_mode, &i_nlink, &ino->i_uid,
+			&ino->i_gid, &i_size, &ino->i_atime, &ino->i_mtime,
+			&ino->i_ctime, &i_blksize, &i_blocks);
+	if(err)
+		return(err);
+
+	ino->i_ino = i_ino;
+	ino->i_mode = i_mode;
+	ino->i_nlink = i_nlink;
+	ino->i_size = i_size;
+	ino->i_blksize = i_blksize;
+	ino->i_blocks = i_blocks;
+	if((ino->i_sb->s_dev == ROOT_DEV) && (ino->i_uid == getuid()))
+		ino->i_uid = 0;
+	return(0);
+}
+
+static char *follow_link(char *link)
+{
+	int len, n;
+	char *name, *resolved, *end;
+
+	len = 64;
+	while(1){
+		n = -ENOMEM;
+		name = kmalloc(len, GFP_KERNEL);
+		if(name == NULL)
+			goto out;
+
+		n = do_readlink(link, name, len);
+		if(n < len)
+			break;
+		len *= 2;
+		kfree(name);
+	}
+	if(n < 0)
+		goto out_free;
+
+	if(*name == '/')
+		return(name);
+
+	end = strrchr(link, '/');
+	if(end == NULL)
+		return(name);
+
+	*(end + 1) = '\0';
+	len = strlen(link) + strlen(name) + 1;
+
+	resolved = kmalloc(len, GFP_KERNEL);
+	if(resolved == NULL){
+		n = -ENOMEM;
+		goto out_free;
+	}
+
+	sprintf(resolved, "%s%s", link, name);
+	kfree(name);
+	kfree(link);
+	return(resolved);
+
+ out_free:
+	kfree(name);
+ out:
+	return(ERR_PTR(n));
+}
+
+static int read_inode(struct inode *ino)
+{
+	char *name;
+	int err = 0;
+
+	/* Unfortunately, we are called from iget() when we don't have a dentry
+	 * allocated yet.
+	 */
+	if(list_empty(&ino->i_dentry))
+		goto out;
+
+	err = -ENOMEM;
+	name = inode_name(ino, 0);
+	if(name == NULL)
+		goto out;
+
+	if(file_type(name, NULL, NULL) == OS_TYPE_SYMLINK){
+		name = follow_link(name);
+		if(IS_ERR(name)){
+			err = PTR_ERR(name);
+			goto out;
+		}
+	}
+
+	err = read_name(ino, name);
+	kfree(name);
+ out:
+	return(err);
+}
+
+int hostfs_statfs(struct super_block *sb, struct kstatfs *sf)
+{
+	/* do_statfs uses struct statfs64 internally, but the linux kernel
+	 * struct statfs still has 32-bit versions for most of these fields,
+	 * so we convert them here
+	 */
+	int err;
+	long long f_blocks;
+	long long f_bfree;
+	long long f_bavail;
+	long long f_files;
+	long long f_ffree;
+
+	err = do_statfs(HOSTFS_I(sb->s_root->d_inode)->host_filename,
+			&sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files,
+			&f_ffree, &sf->f_fsid, sizeof(sf->f_fsid),
+			&sf->f_namelen, sf->f_spare);
+	if(err) return(err);
+	sf->f_blocks = f_blocks;
+	sf->f_bfree = f_bfree;
+	sf->f_bavail = f_bavail;
+	sf->f_files = f_files;
+	sf->f_ffree = f_ffree;
+	sf->f_type = HOSTFS_SUPER_MAGIC;
+	return(0);
+}
+
+static struct inode *hostfs_alloc_inode(struct super_block *sb)
+{
+	struct hostfs_inode_info *hi;
+
+	hi = kmalloc(sizeof(*hi), GFP_KERNEL);
+	if(hi == NULL)
+		return(NULL);
+
+	*hi = ((struct hostfs_inode_info) { .host_filename	= NULL,
+					    .fd			= -1,
+					    .mode		= 0 });
+	inode_init_once(&hi->vfs_inode);
+	return(&hi->vfs_inode);
+}
+
+static void hostfs_delete_inode(struct inode *inode)
+{
+	if(HOSTFS_I(inode)->fd != -1) {
+		close_file(&HOSTFS_I(inode)->fd);
+		HOSTFS_I(inode)->fd = -1;
+	}
+	clear_inode(inode);
+}
+
+static void hostfs_destroy_inode(struct inode *inode)
+{
+	if(HOSTFS_I(inode)->host_filename)
+		kfree(HOSTFS_I(inode)->host_filename);
+
+	/*XXX: This should not happen, probably. The check is here for
+	 * additional safety.*/
+	if(HOSTFS_I(inode)->fd != -1) {
+		close_file(&HOSTFS_I(inode)->fd);
+		printk(KERN_DEBUG "Closing host fd in .destroy_inode\n");
+	}
+
+	kfree(HOSTFS_I(inode));
+}
+
+static void hostfs_read_inode(struct inode *inode)
+{
+	read_inode(inode);
+}
+
+static struct super_operations hostfs_sbops = {
+	.alloc_inode	= hostfs_alloc_inode,
+	.drop_inode	= generic_delete_inode,
+	.delete_inode   = hostfs_delete_inode,
+	.destroy_inode	= hostfs_destroy_inode,
+	.read_inode	= hostfs_read_inode,
+	.statfs		= hostfs_statfs,
+};
+
+int hostfs_readdir(struct file *file, void *ent, filldir_t filldir)
+{
+	void *dir;
+	char *name;
+	unsigned long long next, ino;
+	int error, len;
+
+	name = dentry_name(file->f_dentry, 0);
+	if(name == NULL) return(-ENOMEM);
+	dir = open_dir(name, &error);
+	kfree(name);
+	if(dir == NULL) return(-error);
+	next = file->f_pos;
+	while((name = read_dir(dir, &next, &ino, &len)) != NULL){
+		error = (*filldir)(ent, name, len, file->f_pos,
+				   ino, DT_UNKNOWN);
+		if(error) break;
+		file->f_pos = next;
+	}
+	close_dir(dir);
+	return(0);
+}
+
+int hostfs_file_open(struct inode *ino, struct file *file)
+{
+	char *name;
+	int mode = 0, r = 0, w = 0, fd;
+
+	mode = file->f_mode & (FMODE_READ | FMODE_WRITE);
+	if((mode & HOSTFS_I(ino)->mode) == mode)
+		return(0);
+
+	/* The file may already have been opened, but with the wrong access,
+	 * so this resets things and reopens the file with the new access.
+	 */
+	if(HOSTFS_I(ino)->fd != -1){
+		close_file(&HOSTFS_I(ino)->fd);
+		HOSTFS_I(ino)->fd = -1;
+	}
+
+	HOSTFS_I(ino)->mode |= mode;
+	if(HOSTFS_I(ino)->mode & FMODE_READ)
+		r = 1;
+	if(HOSTFS_I(ino)->mode & FMODE_WRITE)
+		w = 1;
+	if(w)
+		r = 1;
+
+	name = dentry_name(file->f_dentry, 0);
+	if(name == NULL)
+		return(-ENOMEM);
+
+	fd = open_file(name, r, w, append);
+	kfree(name);
+	if(fd < 0) return(fd);
+	FILE_HOSTFS_I(file)->fd = fd;
+
+	return(0);
+}
+
+int hostfs_fsync(struct file *file, struct dentry *dentry, int datasync)
+{
+	return(0);
+}
+
+static struct file_operations hostfs_file_fops = {
+	.llseek		= generic_file_llseek,
+	.read		= generic_file_read,
+	.sendfile	= generic_file_sendfile,
+	.aio_read	= generic_file_aio_read,
+	.aio_write	= generic_file_aio_write,
+	.readv		= generic_file_readv,
+	.writev		= generic_file_writev,
+	.write		= generic_file_write,
+	.mmap		= generic_file_mmap,
+	.open		= hostfs_file_open,
+	.release	= NULL,
+	.fsync		= hostfs_fsync,
+};
+
+static struct file_operations hostfs_dir_fops = {
+	.llseek		= generic_file_llseek,
+	.readdir	= hostfs_readdir,
+	.read		= generic_read_dir,
+};
+
+int hostfs_writepage(struct page *page, struct writeback_control *wbc)
+{
+	struct address_space *mapping = page->mapping;
+	struct inode *inode = mapping->host;
+	char *buffer;
+	unsigned long long base;
+	int count = PAGE_CACHE_SIZE;
+	int end_index = inode->i_size >> PAGE_CACHE_SHIFT;
+	int err;
+
+	if (page->index >= end_index)
+		count = inode->i_size & (PAGE_CACHE_SIZE-1);
+
+	buffer = kmap(page);
+	base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT;
+
+	err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
+	if(err != count){
+		ClearPageUptodate(page);
+		goto out;
+	}
+
+	if (base > inode->i_size)
+		inode->i_size = base;
+
+	if (PageError(page))
+		ClearPageError(page);
+	err = 0;
+
+ out:
+	kunmap(page);
+
+	unlock_page(page);
+	return err;
+}
+
+int hostfs_readpage(struct file *file, struct page *page)
+{
+	char *buffer;
+	long long start;
+	int err = 0;
+
+	start = (long long) page->index << PAGE_CACHE_SHIFT;
+	buffer = kmap(page);
+	err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
+			PAGE_CACHE_SIZE);
+	if(err < 0) goto out;
+
+	memset(&buffer[err], 0, PAGE_CACHE_SIZE - err);
+
+	flush_dcache_page(page);
+	SetPageUptodate(page);
+	if (PageError(page)) ClearPageError(page);
+	err = 0;
+ out:
+	kunmap(page);
+	unlock_page(page);
+	return(err);
+}
+
+int hostfs_prepare_write(struct file *file, struct page *page,
+			 unsigned int from, unsigned int to)
+{
+	char *buffer;
+	long long start, tmp;
+	int err;
+
+	start = (long long) page->index << PAGE_CACHE_SHIFT;
+	buffer = kmap(page);
+	if(from != 0){
+		tmp = start;
+		err = read_file(FILE_HOSTFS_I(file)->fd, &tmp, buffer,
+				from);
+		if(err < 0) goto out;
+	}
+	if(to != PAGE_CACHE_SIZE){
+		start += to;
+		err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer + to,
+				PAGE_CACHE_SIZE - to);
+		if(err < 0) goto out;
+	}
+	err = 0;
+ out:
+	kunmap(page);
+	return(err);
+}
+
+int hostfs_commit_write(struct file *file, struct page *page, unsigned from,
+		 unsigned to)
+{
+	struct address_space *mapping = page->mapping;
+	struct inode *inode = mapping->host;
+	char *buffer;
+	long long start;
+	int err = 0;
+
+	start = (long long) (page->index << PAGE_CACHE_SHIFT) + from;
+	buffer = kmap(page);
+	err = write_file(FILE_HOSTFS_I(file)->fd, &start, buffer + from,
+			 to - from);
+	if(err > 0) err = 0;
+	if(!err && (start > inode->i_size))
+		inode->i_size = start;
+
+	kunmap(page);
+	return(err);
+}
+
+static struct address_space_operations hostfs_aops = {
+	.writepage 	= hostfs_writepage,
+	.readpage	= hostfs_readpage,
+/* 	.set_page_dirty = __set_page_dirty_nobuffers, */
+	.prepare_write	= hostfs_prepare_write,
+	.commit_write	= hostfs_commit_write
+};
+
+static int init_inode(struct inode *inode, struct dentry *dentry)
+{
+	char *name;
+	int type, err = -ENOMEM;
+	int maj, min;
+	dev_t rdev = 0;
+
+	if(dentry){
+		name = dentry_name(dentry, 0);
+		if(name == NULL)
+			goto out;
+		type = file_type(name, &maj, &min);
+		/*Reencode maj and min with the kernel encoding.*/
+		rdev = MKDEV(maj, min);
+		kfree(name);
+	}
+	else type = OS_TYPE_DIR;
+
+	err = 0;
+	if(type == OS_TYPE_SYMLINK)
+		inode->i_op = &page_symlink_inode_operations;
+	else if(type == OS_TYPE_DIR)
+		inode->i_op = &hostfs_dir_iops;
+	else inode->i_op = &hostfs_iops;
+
+	if(type == OS_TYPE_DIR) inode->i_fop = &hostfs_dir_fops;
+	else inode->i_fop = &hostfs_file_fops;
+
+	if(type == OS_TYPE_SYMLINK)
+		inode->i_mapping->a_ops = &hostfs_link_aops;
+	else inode->i_mapping->a_ops = &hostfs_aops;
+
+	switch (type) {
+	case OS_TYPE_CHARDEV:
+		init_special_inode(inode, S_IFCHR, rdev);
+		break;
+	case OS_TYPE_BLOCKDEV:
+		init_special_inode(inode, S_IFBLK, rdev);
+		break;
+	case OS_TYPE_FIFO:
+		init_special_inode(inode, S_IFIFO, 0);
+		break;
+	case OS_TYPE_SOCK:
+		init_special_inode(inode, S_IFSOCK, 0);
+		break;
+	}
+ out:
+	return(err);
+}
+
+int hostfs_create(struct inode *dir, struct dentry *dentry, int mode,
+                 struct nameidata *nd)
+{
+	struct inode *inode;
+	char *name;
+	int error, fd;
+
+	error = -ENOMEM;
+	inode = iget(dir->i_sb, 0);
+	if(inode == NULL) goto out;
+
+	error = init_inode(inode, dentry);
+	if(error)
+		goto out_put;
+
+	error = -ENOMEM;
+	name = dentry_name(dentry, 0);
+	if(name == NULL)
+		goto out_put;
+
+	fd = file_create(name,
+			 mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR,
+			 mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP,
+			 mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH);
+	if(fd < 0)
+		error = fd;
+	else error = read_name(inode, name);
+
+	kfree(name);
+	if(error)
+		goto out_put;
+
+	HOSTFS_I(inode)->fd = fd;
+	HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE;
+	d_instantiate(dentry, inode);
+	return(0);
+
+ out_put:
+	iput(inode);
+ out:
+	return(error);
+}
+
+struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry,
+                            struct nameidata *nd)
+{
+	struct inode *inode;
+	char *name;
+	int err;
+
+	err = -ENOMEM;
+	inode = iget(ino->i_sb, 0);
+	if(inode == NULL)
+		goto out;
+
+	err = init_inode(inode, dentry);
+	if(err)
+		goto out_put;
+
+	err = -ENOMEM;
+	name = dentry_name(dentry, 0);
+	if(name == NULL)
+		goto out_put;
+
+	err = read_name(inode, name);
+	kfree(name);
+	if(err == -ENOENT){
+		iput(inode);
+		inode = NULL;
+	}
+	else if(err)
+		goto out_put;
+
+	d_add(dentry, inode);
+	dentry->d_op = &hostfs_dentry_ops;
+	return(NULL);
+
+ out_put:
+	iput(inode);
+ out:
+	return(ERR_PTR(err));
+}
+
+static char *inode_dentry_name(struct inode *ino, struct dentry *dentry)
+{
+        char *file;
+	int len;
+
+	file = inode_name(ino, dentry->d_name.len + 1);
+	if(file == NULL) return(NULL);
+        strcat(file, "/");
+	len = strlen(file);
+        strncat(file, dentry->d_name.name, dentry->d_name.len);
+	file[len + dentry->d_name.len] = '\0';
+        return(file);
+}
+
+int hostfs_link(struct dentry *to, struct inode *ino, struct dentry *from)
+{
+        char *from_name, *to_name;
+        int err;
+
+        if((from_name = inode_dentry_name(ino, from)) == NULL)
+                return(-ENOMEM);
+        to_name = dentry_name(to, 0);
+	if(to_name == NULL){
+		kfree(from_name);
+		return(-ENOMEM);
+	}
+        err = link_file(to_name, from_name);
+        kfree(from_name);
+        kfree(to_name);
+        return(err);
+}
+
+int hostfs_unlink(struct inode *ino, struct dentry *dentry)
+{
+	char *file;
+	int err;
+
+	if((file = inode_dentry_name(ino, dentry)) == NULL) return(-ENOMEM);
+	if(append)
+		return(-EPERM);
+
+	err = unlink_file(file);
+	kfree(file);
+	return(err);
+}
+
+int hostfs_symlink(struct inode *ino, struct dentry *dentry, const char *to)
+{
+	char *file;
+	int err;
+
+	if((file = inode_dentry_name(ino, dentry)) == NULL) return(-ENOMEM);
+	err = make_symlink(file, to);
+	kfree(file);
+	return(err);
+}
+
+int hostfs_mkdir(struct inode *ino, struct dentry *dentry, int mode)
+{
+	char *file;
+	int err;
+
+	if((file = inode_dentry_name(ino, dentry)) == NULL) return(-ENOMEM);
+	err = do_mkdir(file, mode);
+	kfree(file);
+	return(err);
+}
+
+int hostfs_rmdir(struct inode *ino, struct dentry *dentry)
+{
+	char *file;
+	int err;
+
+	if((file = inode_dentry_name(ino, dentry)) == NULL) return(-ENOMEM);
+	err = do_rmdir(file);
+	kfree(file);
+	return(err);
+}
+
+int hostfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
+{
+	struct inode *inode;
+	char *name;
+	int err = -ENOMEM;
+
+	inode = iget(dir->i_sb, 0);
+	if(inode == NULL)
+		goto out;
+
+	err = init_inode(inode, dentry);
+	if(err)
+		goto out_put;
+
+	err = -ENOMEM;
+	name = dentry_name(dentry, 0);
+	if(name == NULL)
+		goto out_put;
+
+	init_special_inode(inode, mode, dev);
+	err = do_mknod(name, mode, dev);
+	if(err)
+		goto out_free;
+
+	err = read_name(inode, name);
+	kfree(name);
+	if(err)
+		goto out_put;
+
+	d_instantiate(dentry, inode);
+	return(0);
+
+ out_free:
+	kfree(name);
+ out_put:
+	iput(inode);
+ out:
+	return(err);
+}
+
+int hostfs_rename(struct inode *from_ino, struct dentry *from,
+		  struct inode *to_ino, struct dentry *to)
+{
+	char *from_name, *to_name;
+	int err;
+
+	if((from_name = inode_dentry_name(from_ino, from)) == NULL)
+		return(-ENOMEM);
+	if((to_name = inode_dentry_name(to_ino, to)) == NULL){
+		kfree(from_name);
+		return(-ENOMEM);
+	}
+	err = rename_file(from_name, to_name);
+	kfree(from_name);
+	kfree(to_name);
+	return(err);
+}
+
+void hostfs_truncate(struct inode *ino)
+{
+	not_implemented();
+}
+
+int hostfs_permission(struct inode *ino, int desired, struct nameidata *nd)
+{
+	char *name;
+	int r = 0, w = 0, x = 0, err;
+
+	if (desired & MAY_READ) r = 1;
+	if (desired & MAY_WRITE) w = 1;
+	if (desired & MAY_EXEC) x = 1;
+	name = inode_name(ino, 0);
+	if (name == NULL) return(-ENOMEM);
+
+	if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) ||
+			S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode))
+		err = 0;
+	else
+		err = access_file(name, r, w, x);
+	kfree(name);
+	if(!err)
+		err = generic_permission(ino, desired, NULL);
+	return err;
+}
+
+int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
+{
+	struct hostfs_iattr attrs;
+	char *name;
+	int err;
+
+	err = inode_change_ok(dentry->d_inode, attr);
+	if (err)
+		return err;
+
+	if(append)
+		attr->ia_valid &= ~ATTR_SIZE;
+
+	attrs.ia_valid = 0;
+	if(attr->ia_valid & ATTR_MODE){
+		attrs.ia_valid |= HOSTFS_ATTR_MODE;
+		attrs.ia_mode = attr->ia_mode;
+	}
+	if(attr->ia_valid & ATTR_UID){
+		if((dentry->d_inode->i_sb->s_dev == ROOT_DEV) &&
+		   (attr->ia_uid == 0))
+			attr->ia_uid = getuid();
+		attrs.ia_valid |= HOSTFS_ATTR_UID;
+		attrs.ia_uid = attr->ia_uid;
+	}
+	if(attr->ia_valid & ATTR_GID){
+		if((dentry->d_inode->i_sb->s_dev == ROOT_DEV) &&
+		   (attr->ia_gid == 0))
+			attr->ia_gid = getgid();
+		attrs.ia_valid |= HOSTFS_ATTR_GID;
+		attrs.ia_gid = attr->ia_gid;
+	}
+	if(attr->ia_valid & ATTR_SIZE){
+		attrs.ia_valid |= HOSTFS_ATTR_SIZE;
+		attrs.ia_size = attr->ia_size;
+	}
+	if(attr->ia_valid & ATTR_ATIME){
+		attrs.ia_valid |= HOSTFS_ATTR_ATIME;
+		attrs.ia_atime = attr->ia_atime;
+	}
+	if(attr->ia_valid & ATTR_MTIME){
+		attrs.ia_valid |= HOSTFS_ATTR_MTIME;
+		attrs.ia_mtime = attr->ia_mtime;
+	}
+	if(attr->ia_valid & ATTR_CTIME){
+		attrs.ia_valid |= HOSTFS_ATTR_CTIME;
+		attrs.ia_ctime = attr->ia_ctime;
+	}
+	if(attr->ia_valid & ATTR_ATIME_SET){
+		attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET;
+	}
+	if(attr->ia_valid & ATTR_MTIME_SET){
+		attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET;
+	}
+	name = dentry_name(dentry, 0);
+	if(name == NULL) return(-ENOMEM);
+	err = set_attr(name, &attrs);
+	kfree(name);
+	if(err)
+		return(err);
+
+	return(inode_setattr(dentry->d_inode, attr));
+}
+
+int hostfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
+	   struct kstat *stat)
+{
+	generic_fillattr(dentry->d_inode, stat);
+	return(0);
+}
+
+static struct inode_operations hostfs_iops = {
+	.create		= hostfs_create,
+	.link		= hostfs_link,
+	.unlink		= hostfs_unlink,
+	.symlink	= hostfs_symlink,
+	.mkdir		= hostfs_mkdir,
+	.rmdir		= hostfs_rmdir,
+	.mknod		= hostfs_mknod,
+	.rename		= hostfs_rename,
+	.truncate	= hostfs_truncate,
+	.permission	= hostfs_permission,
+	.setattr	= hostfs_setattr,
+	.getattr	= hostfs_getattr,
+};
+
+static struct inode_operations hostfs_dir_iops = {
+	.create		= hostfs_create,
+	.lookup		= hostfs_lookup,
+	.link		= hostfs_link,
+	.unlink		= hostfs_unlink,
+	.symlink	= hostfs_symlink,
+	.mkdir		= hostfs_mkdir,
+	.rmdir		= hostfs_rmdir,
+	.mknod		= hostfs_mknod,
+	.rename		= hostfs_rename,
+	.truncate	= hostfs_truncate,
+	.permission	= hostfs_permission,
+	.setattr	= hostfs_setattr,
+	.getattr	= hostfs_getattr,
+};
+
+int hostfs_link_readpage(struct file *file, struct page *page)
+{
+	char *buffer, *name;
+	long long start;
+	int err;
+
+	start = page->index << PAGE_CACHE_SHIFT;
+	buffer = kmap(page);
+	name = inode_name(page->mapping->host, 0);
+	if(name == NULL) return(-ENOMEM);
+	err = do_readlink(name, buffer, PAGE_CACHE_SIZE);
+	kfree(name);
+	if(err == PAGE_CACHE_SIZE)
+		err = -E2BIG;
+	else if(err > 0){
+		flush_dcache_page(page);
+		SetPageUptodate(page);
+		if (PageError(page)) ClearPageError(page);
+		err = 0;
+	}
+	kunmap(page);
+	unlock_page(page);
+	return(err);
+}
+
+static struct address_space_operations hostfs_link_aops = {
+	.readpage	= hostfs_link_readpage,
+};
+
+static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent)
+{
+	struct inode *root_inode;
+	char *name, *data = d;
+	int err;
+
+	sb->s_blocksize = 1024;
+	sb->s_blocksize_bits = 10;
+	sb->s_magic = HOSTFS_SUPER_MAGIC;
+	sb->s_op = &hostfs_sbops;
+
+	if((data == NULL) || (*data == '\0'))
+		data = root_ino;
+
+	err = -ENOMEM;
+	name = kmalloc(strlen(data) + 1, GFP_KERNEL);
+	if(name == NULL)
+		goto out;
+
+	strcpy(name, data);
+
+	root_inode = iget(sb, 0);
+	if(root_inode == NULL)
+		goto out_free;
+
+	err = init_inode(root_inode, NULL);
+	if(err)
+		goto out_put;
+
+	HOSTFS_I(root_inode)->host_filename = name;
+
+	err = -ENOMEM;
+	sb->s_root = d_alloc_root(root_inode);
+	if(sb->s_root == NULL)
+		goto out_put;
+
+	err = read_inode(root_inode);
+	if(err)
+		goto out_put;
+
+	return(0);
+
+ out_put:
+	iput(root_inode);
+ out_free:
+	kfree(name);
+ out:
+	return(err);
+}
+
+static struct super_block *hostfs_read_sb(struct file_system_type *type,
+					     int flags, const char *dev_name,
+					     void *data)
+{
+	return(get_sb_nodev(type, flags, data, hostfs_fill_sb_common));
+}
+
+static struct file_system_type hostfs_type = {
+	.owner 		= THIS_MODULE,
+	.name 		= "hostfs",
+	.get_sb 	= hostfs_read_sb,
+	.kill_sb	= kill_anon_super,
+	.fs_flags 	= 0,
+};
+
+static int __init init_hostfs(void)
+{
+	return(register_filesystem(&hostfs_type));
+}
+
+static void __exit exit_hostfs(void)
+{
+	unregister_filesystem(&hostfs_type);
+}
+
+module_init(init_hostfs)
+module_exit(exit_hostfs)
+MODULE_LICENSE("GPL");
+
+/*
+ * Overrides for Emacs so that we follow Linus's tabbing style.
+ * Emacs will notice this stuff at the end of the file and automatically
+ * adjust the settings for this buffer only.  This must remain at the end
+ * of the file.
+ * ---------------------------------------------------------------------------
+ * Local variables:
+ * c-file-style: "linux"
+ * End:
+ */