fs/btrfs/super.c - kernel/msm-5.4 - Gitiles

 /*
  * Copyright (C) 2007 Oracle.  All rights reserved.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public
  * License v2 as published by the Free Software Foundation.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * General Public License for more details.
  *
  * You should have received a copy of the GNU General Public
  * License along with this program; if not, write to the
  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  * Boston, MA 021110-1307, USA.
  */

 #include <linux/blkdev.h>
 #include <linux/module.h>
 #include <linux/buffer_head.h>
 #include <linux/fs.h>
 #include <linux/pagemap.h>
 #include <linux/highmem.h>
 #include <linux/time.h>
 #include <linux/init.h>
 #include <linux/string.h>
 #include <linux/smp_lock.h>
 #include <linux/backing-dev.h>
 #include <linux/mount.h>
 #include <linux/mpage.h>
 #include <linux/swap.h>
 #include <linux/writeback.h>
 #include <linux/statfs.h>
 #include <linux/compat.h>
 #include <linux/parser.h>
 #include <linux/ctype.h>
 #include <linux/namei.h>
 #include "ctree.h"
 #include "disk-io.h"
 #include "transaction.h"
 #include "btrfs_inode.h"
 #include "ioctl.h"
 #include "print-tree.h"
 #include "xattr.h"

 #define BTRFS_SUPER_MAGIC 0x9123683E

 static struct super_operations btrfs_super_ops;

 static void btrfs_put_super (struct super_block * sb)
 {
 	struct btrfs_root *root = btrfs_sb(sb);
 	struct btrfs_fs_info *fs = root->fs_info;
 	int ret;

 	ret = close_ctree(root);
 	if (ret) {
 		printk("close ctree returns %d\n", ret);
 	}
 	btrfs_sysfs_del_super(fs);
 	sb->s_fs_info = NULL;
 }

 enum {
 	Opt_subvol, Opt_nodatasum, Opt_nodatacow, Opt_max_extent,
 	Opt_alloc_start, Opt_err,
 };

 static match_table_t tokens = {
 	{Opt_subvol, "subvol=%s"},
 	{Opt_nodatasum, "nodatasum"},
 	{Opt_nodatacow, "nodatacow"},
 	{Opt_max_extent, "max_extent=%s"},
 	{Opt_alloc_start, "alloc_start=%s"},
 	{Opt_err, NULL}
 };

 u64 btrfs_parse_size(char *str)
 {
 	u64 res;
 	int mult = 1;
 	char *end;
 	char last;

 	res = simple_strtoul(str, &end, 10);

 	last = end[0];
 	if (isalpha(last)) {
 		last = tolower(last);
 		switch (last) {
 		case 'g':
 			mult *= 1024;
 		case 'm':
 			mult *= 1024;
 		case 'k':
 			mult *= 1024;
 		}
 		res = res * mult;
 	}
 	return res;
 }

 static int parse_options (char * options,
 			  struct btrfs_root *root,
 			  char **subvol_name)
 {
 	char * p;
 	struct btrfs_fs_info *info = NULL;
 	substring_t args[MAX_OPT_ARGS];

 	if (!options)
 		return 1;

 	/*
 	 * strsep changes the string, duplicate it because parse_options
 	 * gets called twice
 	 */
 	options = kstrdup(options, GFP_NOFS);
 	if (!options)
 		return -ENOMEM;

 	if (root)
 		info = root->fs_info;

 	while ((p = strsep (&options, ",")) != NULL) {
 		int token;
 		if (!*p)
 			continue;

 		token = match_token(p, tokens, args);
 		switch (token) {
 		case Opt_subvol:
 			if (subvol_name) {
 				*subvol_name = match_strdup(&args[0]);
 			}
 			break;
 		case Opt_nodatasum:
 			if (info) {
 				printk("btrfs: setting nodatacsum\n");
 				btrfs_set_opt(info->mount_opt, NODATASUM);
 			}
 			break;
 		case Opt_nodatacow:
 			if (info) {
 				printk("btrfs: setting nodatacow\n");
 				btrfs_set_opt(info->mount_opt, NODATACOW);
 				btrfs_set_opt(info->mount_opt, NODATASUM);
 			}
 			break;
 		case Opt_max_extent:
 			if (info) {
 				char *num = match_strdup(&args[0]);
 				if (num) {
 					info->max_extent =
 						btrfs_parse_size(num);
 					kfree(num);

 					info->max_extent = max_t(u64,
 							 info->max_extent,
 							 root->sectorsize);
 					printk("btrfs: max_extent at %Lu\n",
 					       info->max_extent);
 				}
 			}
 			break;
 		case Opt_alloc_start:
 			if (info) {
 				char *num = match_strdup(&args[0]);
 				if (num) {
 					info->alloc_start =
 						btrfs_parse_size(num);
 					kfree(num);
 					printk("btrfs: allocations start at "
 					       "%Lu\n", info->alloc_start);
 				}
 			}
 			break;
 		default:
 			break;
 		}
 	}
 	kfree(options);
 	return 1;
 }

 static int btrfs_fill_super(struct super_block * sb, void * data, int silent)
 {
 	struct inode * inode;
 	struct dentry * root_dentry;
 	struct btrfs_super_block *disk_super;
 	struct btrfs_root *tree_root;
 	struct btrfs_inode *bi;
 	int err;

 	sb->s_maxbytes = MAX_LFS_FILESIZE;
 	sb->s_magic = BTRFS_SUPER_MAGIC;
 	sb->s_op = &btrfs_super_ops;
 	sb->s_xattr = btrfs_xattr_handlers;
 	sb->s_time_gran = 1;

 	tree_root = open_ctree(sb);

 	if (!tree_root || IS_ERR(tree_root)) {
 		printk("btrfs: open_ctree failed\n");
 		return -EIO;
 	}
 	sb->s_fs_info = tree_root;
 	disk_super = &tree_root->fs_info->super_copy;
 	inode = btrfs_iget_locked(sb, btrfs_super_root_dir(disk_super),
 				  tree_root);
 	bi = BTRFS_I(inode);
 	bi->location.objectid = inode->i_ino;
 	bi->location.offset = 0;
 	bi->root = tree_root;

 	btrfs_set_key_type(&bi->location, BTRFS_INODE_ITEM_KEY);

 	if (!inode) {
 		err = -ENOMEM;
 		goto fail_close;
 	}
 	if (inode->i_state & I_NEW) {
 		btrfs_read_locked_inode(inode);
 		unlock_new_inode(inode);
 	}

 	root_dentry = d_alloc_root(inode);
 	if (!root_dentry) {
 		iput(inode);
 		err = -ENOMEM;
 		goto fail_close;
 	}

 	parse_options((char *)data, tree_root, NULL);

 	/* this does the super kobj at the same time */
 	err = btrfs_sysfs_add_super(tree_root->fs_info);
 	if (err)
 		goto fail_close;

 	sb->s_root = root_dentry;
 	btrfs_transaction_queue_work(tree_root, HZ * 30);
 	return 0;

 fail_close:
 	close_ctree(tree_root);
 	return err;
 }

 static int btrfs_sync_fs(struct super_block *sb, int wait)
 {
 	struct btrfs_trans_handle *trans;
 	struct btrfs_root *root;
 	int ret;
 	root = btrfs_sb(sb);

 	sb->s_dirt = 0;
 	if (!wait) {
 		filemap_flush(root->fs_info->btree_inode->i_mapping);
 		return 0;
 	}
 	btrfs_clean_old_snapshots(root);
 	mutex_lock(&root->fs_info->fs_mutex);
 	btrfs_defrag_dirty_roots(root->fs_info);
 	trans = btrfs_start_transaction(root, 1);
 	ret = btrfs_commit_transaction(trans, root);
 	sb->s_dirt = 0;
 	mutex_unlock(&root->fs_info->fs_mutex);
 	return ret;
 }

 static void btrfs_write_super(struct super_block *sb)
 {
 	sb->s_dirt = 0;
 }

 /*
  * This is almost a copy of get_sb_bdev in fs/super.c.
  * We need the local copy to allow direct mounting of
  * subvolumes, but this could be easily integrated back
  * into the generic version.  --hch
  */

 /* start copy & paste */
 static int set_bdev_super(struct super_block *s, void *data)
 {
 	s->s_bdev = data;
 	s->s_dev = s->s_bdev->bd_dev;
 	return 0;
 }

 static int test_bdev_super(struct super_block *s, void *data)
 {
 	return (void *)s->s_bdev == data;
 }

 int btrfs_get_sb_bdev(struct file_system_type *fs_type,
 	int flags, const char *dev_name, void *data,
 	int (*fill_super)(struct super_block *, void *, int),
 	struct vfsmount *mnt, const char *subvol)
 {
 	struct block_device *bdev = NULL;
 	struct super_block *s;
 	struct dentry *root;
 	int error = 0;

 	bdev = open_bdev_excl(dev_name, flags, fs_type);
 	if (IS_ERR(bdev))
 		return PTR_ERR(bdev);

 	/*
 	 * once the super is inserted into the list by sget, s_umount
 	 * will protect the lockfs code from trying to start a snapshot
 	 * while we are mounting
 	 */
 	down(&bdev->bd_mount_sem);
 	s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
 	up(&bdev->bd_mount_sem);
 	if (IS_ERR(s))
 		goto error_s;

 	if (s->s_root) {
 		if ((flags ^ s->s_flags) & MS_RDONLY) {
 			up_write(&s->s_umount);
 			deactivate_super(s);
 			error = -EBUSY;
 			goto error_bdev;
 		}

 		close_bdev_excl(bdev);
 	} else {
 		char b[BDEVNAME_SIZE];

 		s->s_flags = flags;
 		strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
 		sb_set_blocksize(s, block_size(bdev));
 		error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
 		if (error) {
 			up_write(&s->s_umount);
 			deactivate_super(s);
 			goto error;
 		}

 		s->s_flags |= MS_ACTIVE;
 	}

 	if (subvol) {
 		root = lookup_one_len(subvol, s->s_root, strlen(subvol));
 		if (IS_ERR(root)) {
 			up_write(&s->s_umount);
 			deactivate_super(s);
 			error = PTR_ERR(root);
 			goto error;
 		}
 		if (!root->d_inode) {
 			dput(root);
 			up_write(&s->s_umount);
 			deactivate_super(s);
 			error = -ENXIO;
 			goto error;
 		}
 	} else {
 		root = dget(s->s_root);
 	}

 	mnt->mnt_sb = s;
 	mnt->mnt_root = root;
 	return 0;

 error_s:
 	error = PTR_ERR(s);
 error_bdev:
 	close_bdev_excl(bdev);
 error:
 	return error;
 }
 /* end copy & paste */

 static int btrfs_get_sb(struct file_system_type *fs_type,
 	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
 {
 	int ret;
 	char *subvol_name = NULL;

 	parse_options((char *)data, NULL, &subvol_name);
 	ret = btrfs_get_sb_bdev(fs_type, flags, dev_name, data,
 			btrfs_fill_super, mnt,
 			subvol_name ? subvol_name : "default");
 	if (subvol_name)
 		kfree(subvol_name);
 	return ret;
 }

 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
 	struct btrfs_root *root = btrfs_sb(dentry->d_sb);
 	struct btrfs_super_block *disk_super = &root->fs_info->super_copy;
 	int bits = dentry->d_sb->s_blocksize_bits;

 	buf->f_namelen = BTRFS_NAME_LEN;
 	buf->f_blocks = btrfs_super_total_bytes(disk_super) >> bits;
 	buf->f_bfree = buf->f_blocks -
 		(btrfs_super_bytes_used(disk_super) >> bits);
 	buf->f_bavail = buf->f_bfree;
 	buf->f_bsize = dentry->d_sb->s_blocksize;
 	buf->f_type = BTRFS_SUPER_MAGIC;
 	return 0;
 }

 static struct file_system_type btrfs_fs_type = {
 	.owner		= THIS_MODULE,
 	.name		= "btrfs",
 	.get_sb		= btrfs_get_sb,
 	.kill_sb	= kill_block_super,
 	.fs_flags	= FS_REQUIRES_DEV,
 };

 static struct super_operations btrfs_super_ops = {
 	.delete_inode	= btrfs_delete_inode,
 	.put_super	= btrfs_put_super,
 	.read_inode	= btrfs_read_locked_inode,
 	.write_super	= btrfs_write_super,
 	.sync_fs	= btrfs_sync_fs,
 	.write_inode	= btrfs_write_inode,
 	.dirty_inode	= btrfs_dirty_inode,
 	.alloc_inode	= btrfs_alloc_inode,
 	.destroy_inode	= btrfs_destroy_inode,
 	.statfs		= btrfs_statfs,
 };

 static int __init init_btrfs_fs(void)
 {
 	int err;

 	err = btrfs_init_sysfs();
 	if (err)
 		return err;

 	btrfs_init_transaction_sys();
 	err = btrfs_init_cachep();
 	if (err)
 		goto free_transaction_sys;
 	err = extent_map_init();
 	if (err)
 		goto free_cachep;

 	err = register_filesystem(&btrfs_fs_type);
 	if (err)
 		goto free_extent_map;
 	return 0;

 free_extent_map:
 	extent_map_exit();
 free_cachep:
 	btrfs_destroy_cachep();
 free_transaction_sys:
 	btrfs_exit_transaction_sys();
 	btrfs_exit_sysfs();
 	return err;
 }

 static void __exit exit_btrfs_fs(void)
 {
 	btrfs_exit_transaction_sys();
 	btrfs_destroy_cachep();
 	extent_map_exit();
 	unregister_filesystem(&btrfs_fs_type);
 	btrfs_exit_sysfs();
 }

 module_init(init_btrfs_fs)
 module_exit(exit_btrfs_fs)

 MODULE_LICENSE("GPL");
	/*
	* Copyright (C) 2007 Oracle. All rights reserved.
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public
	* License v2 as published by the Free Software Foundation.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* General Public License for more details.
	*
	* You should have received a copy of the GNU General Public
	* License along with this program; if not, write to the
	* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
	* Boston, MA 021110-1307, USA.
	*/

	#include <linux/blkdev.h>
	#include <linux/module.h>
	#include <linux/buffer_head.h>
	#include <linux/fs.h>
	#include <linux/pagemap.h>
	#include <linux/highmem.h>
	#include <linux/time.h>
	#include <linux/init.h>
	#include <linux/string.h>
	#include <linux/smp_lock.h>
	#include <linux/backing-dev.h>
	#include <linux/mount.h>
	#include <linux/mpage.h>
	#include <linux/swap.h>
	#include <linux/writeback.h>
	#include <linux/statfs.h>
	#include <linux/compat.h>
	#include <linux/parser.h>
	#include <linux/ctype.h>
	#include <linux/namei.h>
	#include "ctree.h"
	#include "disk-io.h"
	#include "transaction.h"
	#include "btrfs_inode.h"
	#include "ioctl.h"
	#include "print-tree.h"
	#include "xattr.h"

	#define BTRFS_SUPER_MAGIC 0x9123683E

	static struct super_operations btrfs_super_ops;

	static void btrfs_put_super (struct super_block * sb)
	{
	struct btrfs_root *root = btrfs_sb(sb);
	struct btrfs_fs_info *fs = root->fs_info;
	int ret;

	ret = close_ctree(root);
	if (ret) {
	printk("close ctree returns %d\n", ret);
	}
	btrfs_sysfs_del_super(fs);
	sb->s_fs_info = NULL;
	}

	enum {
	Opt_subvol, Opt_nodatasum, Opt_nodatacow, Opt_max_extent,
	Opt_alloc_start, Opt_err,
	};

	static match_table_t tokens = {
	{Opt_subvol, "subvol=%s"},
	{Opt_nodatasum, "nodatasum"},
	{Opt_nodatacow, "nodatacow"},
	{Opt_max_extent, "max_extent=%s"},
	{Opt_alloc_start, "alloc_start=%s"},
	{Opt_err, NULL}
	};

	u64 btrfs_parse_size(char *str)
	{
	u64 res;
	int mult = 1;
	char *end;
	char last;

	res = simple_strtoul(str, &end, 10);

	last = end[0];
	if (isalpha(last)) {
	last = tolower(last);
	switch (last) {
	case 'g':
	mult *= 1024;
	case 'm':
	mult *= 1024;
	case 'k':
	mult *= 1024;
	}
	res = res * mult;
	}
	return res;
	}

	static int parse_options (char * options,
	struct btrfs_root *root,
	char **subvol_name)
	{
	char * p;
	struct btrfs_fs_info *info = NULL;
	substring_t args[MAX_OPT_ARGS];

	if (!options)
	return 1;

	/*
	* strsep changes the string, duplicate it because parse_options
	* gets called twice
	*/
	options = kstrdup(options, GFP_NOFS);
	if (!options)
	return -ENOMEM;

	if (root)
	info = root->fs_info;

	while ((p = strsep (&options, ",")) != NULL) {
	int token;
	if (!*p)
	continue;

	token = match_token(p, tokens, args);
	switch (token) {
	case Opt_subvol:
	if (subvol_name) {
	*subvol_name = match_strdup(&args[0]);
	}
	break;
	case Opt_nodatasum:
	if (info) {
	printk("btrfs: setting nodatacsum\n");
	btrfs_set_opt(info->mount_opt, NODATASUM);
	}
	break;
	case Opt_nodatacow:
	if (info) {
	printk("btrfs: setting nodatacow\n");
	btrfs_set_opt(info->mount_opt, NODATACOW);
	btrfs_set_opt(info->mount_opt, NODATASUM);
	}
	break;
	case Opt_max_extent:
	if (info) {
	char *num = match_strdup(&args[0]);
	if (num) {
	info->max_extent =
	btrfs_parse_size(num);
	kfree(num);

	info->max_extent = max_t(u64,
	info->max_extent,
	root->sectorsize);
	printk("btrfs: max_extent at %Lu\n",
	info->max_extent);
	}
	}
	break;
	case Opt_alloc_start:
	if (info) {
	char *num = match_strdup(&args[0]);
	if (num) {
	info->alloc_start =
	btrfs_parse_size(num);
	kfree(num);
	printk("btrfs: allocations start at "
	"%Lu\n", info->alloc_start);
	}
	}
	break;
	default:
	break;
	}
	}
	kfree(options);
	return 1;
	}

	static int btrfs_fill_super(struct super_block * sb, void * data, int silent)
	{
	struct inode * inode;
	struct dentry * root_dentry;
	struct btrfs_super_block *disk_super;
	struct btrfs_root *tree_root;
	struct btrfs_inode *bi;
	int err;

	sb->s_maxbytes = MAX_LFS_FILESIZE;
	sb->s_magic = BTRFS_SUPER_MAGIC;
	sb->s_op = &btrfs_super_ops;
	sb->s_xattr = btrfs_xattr_handlers;
	sb->s_time_gran = 1;

	tree_root = open_ctree(sb);

	if (!tree_root \|\| IS_ERR(tree_root)) {
	printk("btrfs: open_ctree failed\n");
	return -EIO;
	}
	sb->s_fs_info = tree_root;
	disk_super = &tree_root->fs_info->super_copy;
	inode = btrfs_iget_locked(sb, btrfs_super_root_dir(disk_super),
	tree_root);
	bi = BTRFS_I(inode);
	bi->location.objectid = inode->i_ino;
	bi->location.offset = 0;
	bi->root = tree_root;

	btrfs_set_key_type(&bi->location, BTRFS_INODE_ITEM_KEY);

	if (!inode) {
	err = -ENOMEM;
	goto fail_close;
	}
	if (inode->i_state & I_NEW) {
	btrfs_read_locked_inode(inode);
	unlock_new_inode(inode);
	}

	root_dentry = d_alloc_root(inode);
	if (!root_dentry) {
	iput(inode);
	err = -ENOMEM;
	goto fail_close;
	}

	parse_options((char *)data, tree_root, NULL);

	/* this does the super kobj at the same time */
	err = btrfs_sysfs_add_super(tree_root->fs_info);
	if (err)
	goto fail_close;

	sb->s_root = root_dentry;
	btrfs_transaction_queue_work(tree_root, HZ * 30);
	return 0;

	fail_close:
	close_ctree(tree_root);
	return err;
	}

	static int btrfs_sync_fs(struct super_block *sb, int wait)
	{
	struct btrfs_trans_handle *trans;
	struct btrfs_root *root;
	int ret;
	root = btrfs_sb(sb);

	sb->s_dirt = 0;
	if (!wait) {
	filemap_flush(root->fs_info->btree_inode->i_mapping);
	return 0;
	}
	btrfs_clean_old_snapshots(root);
	mutex_lock(&root->fs_info->fs_mutex);
	btrfs_defrag_dirty_roots(root->fs_info);
	trans = btrfs_start_transaction(root, 1);
	ret = btrfs_commit_transaction(trans, root);
	sb->s_dirt = 0;
	mutex_unlock(&root->fs_info->fs_mutex);
	return ret;
	}

	static void btrfs_write_super(struct super_block *sb)
	{
	sb->s_dirt = 0;
	}

	/*
	* This is almost a copy of get_sb_bdev in fs/super.c.
	* We need the local copy to allow direct mounting of
	* subvolumes, but this could be easily integrated back
	* into the generic version. --hch
	*/

	/* start copy & paste */
	static int set_bdev_super(struct super_block s, void data)
	{
	s->s_bdev = data;
	s->s_dev = s->s_bdev->bd_dev;
	return 0;
	}

	static int test_bdev_super(struct super_block s, void data)
	{
	return (void *)s->s_bdev == data;
	}

	int btrfs_get_sb_bdev(struct file_system_type *fs_type,
	int flags, const char dev_name, void data,
	int (fill_super)(struct super_block , void *, int),
	struct vfsmount mnt, const char subvol)
	{
	struct block_device *bdev = NULL;
	struct super_block *s;
	struct dentry *root;
	int error = 0;

	bdev = open_bdev_excl(dev_name, flags, fs_type);
	if (IS_ERR(bdev))
	return PTR_ERR(bdev);

	/*
	* once the super is inserted into the list by sget, s_umount
	* will protect the lockfs code from trying to start a snapshot
	* while we are mounting
	*/
	down(&bdev->bd_mount_sem);
	s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
	up(&bdev->bd_mount_sem);
	if (IS_ERR(s))
	goto error_s;

	if (s->s_root) {
	if ((flags ^ s->s_flags) & MS_RDONLY) {
	up_write(&s->s_umount);
	deactivate_super(s);
	error = -EBUSY;
	goto error_bdev;
	}

	close_bdev_excl(bdev);
	} else {
	char b[BDEVNAME_SIZE];

	s->s_flags = flags;
	strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
	sb_set_blocksize(s, block_size(bdev));
	error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
	if (error) {
	up_write(&s->s_umount);
	deactivate_super(s);
	goto error;
	}

	s->s_flags \|= MS_ACTIVE;
	}

	if (subvol) {
	root = lookup_one_len(subvol, s->s_root, strlen(subvol));
	if (IS_ERR(root)) {
	up_write(&s->s_umount);
	deactivate_super(s);
	error = PTR_ERR(root);
	goto error;
	}
	if (!root->d_inode) {
	dput(root);
	up_write(&s->s_umount);
	deactivate_super(s);
	error = -ENXIO;
	goto error;
	}
	} else {
	root = dget(s->s_root);
	}

	mnt->mnt_sb = s;
	mnt->mnt_root = root;
	return 0;

	error_s:
	error = PTR_ERR(s);
	error_bdev:
	close_bdev_excl(bdev);
	error:
	return error;
	}
	/* end copy & paste */

	static int btrfs_get_sb(struct file_system_type *fs_type,
	int flags, const char dev_name, void data, struct vfsmount *mnt)
	{
	int ret;
	char *subvol_name = NULL;

	parse_options((char *)data, NULL, &subvol_name);
	ret = btrfs_get_sb_bdev(fs_type, flags, dev_name, data,
	btrfs_fill_super, mnt,
	subvol_name ? subvol_name : "default");
	if (subvol_name)
	kfree(subvol_name);
	return ret;
	}

	static int btrfs_statfs(struct dentry dentry, struct kstatfs buf)
	{
	struct btrfs_root *root = btrfs_sb(dentry->d_sb);
	struct btrfs_super_block *disk_super = &root->fs_info->super_copy;
	int bits = dentry->d_sb->s_blocksize_bits;

	buf->f_namelen = BTRFS_NAME_LEN;
	buf->f_blocks = btrfs_super_total_bytes(disk_super) >> bits;
	buf->f_bfree = buf->f_blocks -
	(btrfs_super_bytes_used(disk_super) >> bits);
	buf->f_bavail = buf->f_bfree;
	buf->f_bsize = dentry->d_sb->s_blocksize;
	buf->f_type = BTRFS_SUPER_MAGIC;
	return 0;
	}

	static struct file_system_type btrfs_fs_type = {
	.owner = THIS_MODULE,
	.name = "btrfs",
	.get_sb = btrfs_get_sb,
	.kill_sb = kill_block_super,
	.fs_flags = FS_REQUIRES_DEV,
	};

	static struct super_operations btrfs_super_ops = {
	.delete_inode = btrfs_delete_inode,
	.put_super = btrfs_put_super,
	.read_inode = btrfs_read_locked_inode,
	.write_super = btrfs_write_super,
	.sync_fs = btrfs_sync_fs,
	.write_inode = btrfs_write_inode,
	.dirty_inode = btrfs_dirty_inode,
	.alloc_inode = btrfs_alloc_inode,
	.destroy_inode = btrfs_destroy_inode,
	.statfs = btrfs_statfs,
	};

	static int __init init_btrfs_fs(void)
	{
	int err;

	err = btrfs_init_sysfs();
	if (err)
	return err;

	btrfs_init_transaction_sys();
	err = btrfs_init_cachep();
	if (err)
	goto free_transaction_sys;
	err = extent_map_init();
	if (err)
	goto free_cachep;

	err = register_filesystem(&btrfs_fs_type);
	if (err)
	goto free_extent_map;
	return 0;

	free_extent_map:
	extent_map_exit();
	free_cachep:
	btrfs_destroy_cachep();
	free_transaction_sys:
	btrfs_exit_transaction_sys();
	btrfs_exit_sysfs();
	return err;
	}

	static void __exit exit_btrfs_fs(void)
	{
	btrfs_exit_transaction_sys();
	btrfs_destroy_cachep();
	extent_map_exit();
	unregister_filesystem(&btrfs_fs_type);
	btrfs_exit_sysfs();
	}

	module_init(init_btrfs_fs)
	module_exit(exit_btrfs_fs)

	MODULE_LICENSE("GPL");