fs/btrfs/super.c - kernel/msm-4.9 - 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/seq_file.h>
 #include <linux/string.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 <linux/miscdevice.h>
 #include <linux/magic.h>
 #include "compat.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"
 #include "volumes.h"
 #include "version.h"
 #include "export.h"
 #include "compression.h"

 static const struct super_operations btrfs_super_ops;

 static void btrfs_put_super(struct super_block *sb)
 {
 	struct btrfs_root *root = btrfs_sb(sb);
 	int ret;

 	ret = close_ctree(root);
 	sb->s_fs_info = NULL;
 }

 enum {
 	Opt_degraded, Opt_subvol, Opt_device, Opt_nodatasum, Opt_nodatacow,
 	Opt_max_extent, Opt_max_inline, Opt_alloc_start, Opt_nobarrier,
 	Opt_ssd, Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl,
 	Opt_compress, Opt_notreelog, Opt_ratio, Opt_flushoncommit,
 	Opt_discard, Opt_err,
 };

 static match_table_t tokens = {
 	{Opt_degraded, "degraded"},
 	{Opt_subvol, "subvol=%s"},
 	{Opt_device, "device=%s"},
 	{Opt_nodatasum, "nodatasum"},
 	{Opt_nodatacow, "nodatacow"},
 	{Opt_nobarrier, "nobarrier"},
 	{Opt_max_extent, "max_extent=%s"},
 	{Opt_max_inline, "max_inline=%s"},
 	{Opt_alloc_start, "alloc_start=%s"},
 	{Opt_thread_pool, "thread_pool=%d"},
 	{Opt_compress, "compress"},
 	{Opt_ssd, "ssd"},
 	{Opt_ssd_spread, "ssd_spread"},
 	{Opt_nossd, "nossd"},
 	{Opt_noacl, "noacl"},
 	{Opt_notreelog, "notreelog"},
 	{Opt_flushoncommit, "flushoncommit"},
 	{Opt_ratio, "metadata_ratio=%d"},
 	{Opt_discard, "discard"},
 	{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;
 }

 /*
  * Regular mount options parser.  Everything that is needed only when
  * reading in a new superblock is parsed here.
  */
 int btrfs_parse_options(struct btrfs_root *root, char *options)
 {
 	struct btrfs_fs_info *info = root->fs_info;
 	substring_t args[MAX_OPT_ARGS];
 	char *p, *num;
 	int intarg;
 	int ret = 0;

 	if (!options)
 		return 0;

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


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

 		token = match_token(p, tokens, args);
 		switch (token) {
 		case Opt_degraded:
 			printk(KERN_INFO "btrfs: allowing degraded mounts\n");
 			btrfs_set_opt(info->mount_opt, DEGRADED);
 			break;
 		case Opt_subvol:
 		case Opt_device:
 			/*
 			 * These are parsed by btrfs_parse_early_options
 			 * and can be happily ignored here.
 			 */
 			break;
 		case Opt_nodatasum:
 			printk(KERN_INFO "btrfs: setting nodatasum\n");
 			btrfs_set_opt(info->mount_opt, NODATASUM);
 			break;
 		case Opt_nodatacow:
 			printk(KERN_INFO "btrfs: setting nodatacow\n");
 			btrfs_set_opt(info->mount_opt, NODATACOW);
 			btrfs_set_opt(info->mount_opt, NODATASUM);
 			break;
 		case Opt_compress:
 			printk(KERN_INFO "btrfs: use compression\n");
 			btrfs_set_opt(info->mount_opt, COMPRESS);
 			break;
 		case Opt_ssd:
 			printk(KERN_INFO "btrfs: use ssd allocation scheme\n");
 			btrfs_set_opt(info->mount_opt, SSD);
 			break;
 		case Opt_ssd_spread:
 			printk(KERN_INFO "btrfs: use spread ssd "
 			       "allocation scheme\n");
 			btrfs_set_opt(info->mount_opt, SSD);
 			btrfs_set_opt(info->mount_opt, SSD_SPREAD);
 			break;
 		case Opt_nossd:
 			printk(KERN_INFO "btrfs: not using ssd allocation "
 			       "scheme\n");
 			btrfs_set_opt(info->mount_opt, NOSSD);
 			btrfs_clear_opt(info->mount_opt, SSD);
 			btrfs_clear_opt(info->mount_opt, SSD_SPREAD);
 			break;
 		case Opt_nobarrier:
 			printk(KERN_INFO "btrfs: turning off barriers\n");
 			btrfs_set_opt(info->mount_opt, NOBARRIER);
 			break;
 		case Opt_thread_pool:
 			intarg = 0;
 			match_int(&args[0], &intarg);
 			if (intarg) {
 				info->thread_pool_size = intarg;
 				printk(KERN_INFO "btrfs: thread pool %d\n",
 				       info->thread_pool_size);
 			}
 			break;
 		case Opt_max_extent:
 			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(KERN_INFO "btrfs: max_extent at %llu\n",
 				       (unsigned long long)info->max_extent);
 			}
 			break;
 		case Opt_max_inline:
 			num = match_strdup(&args[0]);
 			if (num) {
 				info->max_inline = btrfs_parse_size(num);
 				kfree(num);

 				if (info->max_inline) {
 					info->max_inline = max_t(u64,
 						info->max_inline,
 						root->sectorsize);
 				}
 				printk(KERN_INFO "btrfs: max_inline at %llu\n",
 					(unsigned long long)info->max_inline);
 			}
 			break;
 		case Opt_alloc_start:
 			num = match_strdup(&args[0]);
 			if (num) {
 				info->alloc_start = btrfs_parse_size(num);
 				kfree(num);
 				printk(KERN_INFO
 					"btrfs: allocations start at %llu\n",
 					(unsigned long long)info->alloc_start);
 			}
 			break;
 		case Opt_noacl:
 			root->fs_info->sb->s_flags &= ~MS_POSIXACL;
 			break;
 		case Opt_notreelog:
 			printk(KERN_INFO "btrfs: disabling tree log\n");
 			btrfs_set_opt(info->mount_opt, NOTREELOG);
 			break;
 		case Opt_flushoncommit:
 			printk(KERN_INFO "btrfs: turning on flush-on-commit\n");
 			btrfs_set_opt(info->mount_opt, FLUSHONCOMMIT);
 			break;
 		case Opt_ratio:
 			intarg = 0;
 			match_int(&args[0], &intarg);
 			if (intarg) {
 				info->metadata_ratio = intarg;
 				printk(KERN_INFO "btrfs: metadata ratio %d\n",
 				       info->metadata_ratio);
 			}
 			break;
 		case Opt_discard:
 			btrfs_set_opt(info->mount_opt, DISCARD);
 			break;
 		case Opt_err:
 			printk(KERN_INFO "btrfs: unrecognized mount option "
 			       "'%s'\n", p);
 			ret = -EINVAL;
 			goto out;
 		default:
 			break;
 		}
 	}
 out:
 	kfree(options);
 	return ret;
 }

 /*
  * Parse mount options that are required early in the mount process.
  *
  * All other options will be parsed on much later in the mount process and
  * only when we need to allocate a new super block.
  */
 static int btrfs_parse_early_options(const char *options, fmode_t flags,
 		void *holder, char **subvol_name,
 		struct btrfs_fs_devices **fs_devices)
 {
 	substring_t args[MAX_OPT_ARGS];
 	char *opts, *p;
 	int error = 0;

 	if (!options)
 		goto out;

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

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

 		token = match_token(p, tokens, args);
 		switch (token) {
 		case Opt_subvol:
 			*subvol_name = match_strdup(&args[0]);
 			break;
 		case Opt_device:
 			error = btrfs_scan_one_device(match_strdup(&args[0]),
 					flags, holder, fs_devices);
 			if (error)
 				goto out_free_opts;
 			break;
 		default:
 			break;
 		}
 	}

  out_free_opts:
 	kfree(opts);
  out:
 	/*
 	 * If no subvolume name is specified we use the default one.  Allocate
 	 * a copy of the string "." here so that code later in the
 	 * mount path doesn't care if it's the default volume or another one.
 	 */
 	if (!*subvol_name) {
 		*subvol_name = kstrdup(".", GFP_KERNEL);
 		if (!*subvol_name)
 			return -ENOMEM;
 	}
 	return error;
 }

 static int btrfs_fill_super(struct super_block *sb,
 			    struct btrfs_fs_devices *fs_devices,
 			    void *data, int silent)
 {
 	struct inode *inode;
 	struct dentry *root_dentry;
 	struct btrfs_super_block *disk_super;
 	struct btrfs_root *tree_root;
 	struct btrfs_key key;
 	int err;

 	sb->s_maxbytes = MAX_LFS_FILESIZE;
 	sb->s_magic = BTRFS_SUPER_MAGIC;
 	sb->s_op = &btrfs_super_ops;
 	sb->s_export_op = &btrfs_export_ops;
 	sb->s_xattr = btrfs_xattr_handlers;
 	sb->s_time_gran = 1;
 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
 	sb->s_flags |= MS_POSIXACL;
 #endif

 	tree_root = open_ctree(sb, fs_devices, (char *)data);

 	if (IS_ERR(tree_root)) {
 		printk("btrfs: open_ctree failed\n");
 		return PTR_ERR(tree_root);
 	}
 	sb->s_fs_info = tree_root;
 	disk_super = &tree_root->fs_info->super_copy;

 	key.objectid = BTRFS_FIRST_FREE_OBJECTID;
 	key.type = BTRFS_INODE_ITEM_KEY;
 	key.offset = 0;
 	inode = btrfs_iget(sb, &key, tree_root->fs_info->fs_root);
 	if (IS_ERR(inode)) {
 		err = PTR_ERR(inode);
 		goto fail_close;
 	}

 	root_dentry = d_alloc_root(inode);
 	if (!root_dentry) {
 		iput(inode);
 		err = -ENOMEM;
 		goto fail_close;
 	}
 #if 0
 	/* this does the super kobj at the same time */
 	err = btrfs_sysfs_add_super(tree_root->fs_info);
 	if (err)
 		goto fail_close;
 #endif

 	sb->s_root = root_dentry;

 	save_mount_options(sb, data);
 	return 0;

 fail_close:
 	close_ctree(tree_root);
 	return err;
 }

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

 	if (!wait) {
 		filemap_flush(root->fs_info->btree_inode->i_mapping);
 		return 0;
 	}

 	btrfs_start_delalloc_inodes(root, 0);
 	btrfs_wait_ordered_extents(root, 0, 0);

 	trans = btrfs_start_transaction(root, 1);
 	ret = btrfs_commit_transaction(trans, root);
 	return ret;
 }

 static int btrfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
 {
 	struct btrfs_root *root = btrfs_sb(vfs->mnt_sb);
 	struct btrfs_fs_info *info = root->fs_info;

 	if (btrfs_test_opt(root, DEGRADED))
 		seq_puts(seq, ",degraded");
 	if (btrfs_test_opt(root, NODATASUM))
 		seq_puts(seq, ",nodatasum");
 	if (btrfs_test_opt(root, NODATACOW))
 		seq_puts(seq, ",nodatacow");
 	if (btrfs_test_opt(root, NOBARRIER))
 		seq_puts(seq, ",nobarrier");
 	if (info->max_extent != (u64)-1)
 		seq_printf(seq, ",max_extent=%llu",
 			   (unsigned long long)info->max_extent);
 	if (info->max_inline != 8192 * 1024)
 		seq_printf(seq, ",max_inline=%llu",
 			   (unsigned long long)info->max_inline);
 	if (info->alloc_start != 0)
 		seq_printf(seq, ",alloc_start=%llu",
 			   (unsigned long long)info->alloc_start);
 	if (info->thread_pool_size !=  min_t(unsigned long,
 					     num_online_cpus() + 2, 8))
 		seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
 	if (btrfs_test_opt(root, COMPRESS))
 		seq_puts(seq, ",compress");
 	if (btrfs_test_opt(root, NOSSD))
 		seq_puts(seq, ",nossd");
 	if (btrfs_test_opt(root, SSD_SPREAD))
 		seq_puts(seq, ",ssd_spread");
 	else if (btrfs_test_opt(root, SSD))
 		seq_puts(seq, ",ssd");
 	if (btrfs_test_opt(root, NOTREELOG))
 		seq_puts(seq, ",notreelog");
 	if (btrfs_test_opt(root, FLUSHONCOMMIT))
 		seq_puts(seq, ",flushoncommit");
 	if (btrfs_test_opt(root, DISCARD))
 		seq_puts(seq, ",discard");
 	if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
 		seq_puts(seq, ",noacl");
 	return 0;
 }

 static int btrfs_test_super(struct super_block *s, void *data)
 {
 	struct btrfs_fs_devices *test_fs_devices = data;
 	struct btrfs_root *root = btrfs_sb(s);

 	return root->fs_info->fs_devices == test_fs_devices;
 }

 /*
  * Find a superblock for the given device / mount point.
  *
  * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
  *	  for multiple device setup.  Make sure to keep it in sync.
  */
 static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
 		const char *dev_name, void *data, struct vfsmount *mnt)
 {
 	char *subvol_name = NULL;
 	struct block_device *bdev = NULL;
 	struct super_block *s;
 	struct dentry *root;
 	struct btrfs_fs_devices *fs_devices = NULL;
 	fmode_t mode = FMODE_READ;
 	int error = 0;

 	if (!(flags & MS_RDONLY))
 		mode |= FMODE_WRITE;

 	error = btrfs_parse_early_options(data, mode, fs_type,
 					  &subvol_name, &fs_devices);
 	if (error)
 		return error;

 	error = btrfs_scan_one_device(dev_name, mode, fs_type, &fs_devices);
 	if (error)
 		goto error_free_subvol_name;

 	error = btrfs_open_devices(fs_devices, mode, fs_type);
 	if (error)
 		goto error_free_subvol_name;

 	if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
 		error = -EACCES;
 		goto error_close_devices;
 	}

 	bdev = fs_devices->latest_bdev;
 	s = sget(fs_type, btrfs_test_super, set_anon_super, fs_devices);
 	if (IS_ERR(s))
 		goto error_s;

 	if (s->s_root) {
 		if ((flags ^ s->s_flags) & MS_RDONLY) {
 			deactivate_locked_super(s);
 			error = -EBUSY;
 			goto error_close_devices;
 		}

 		btrfs_close_devices(fs_devices);
 	} else {
 		char b[BDEVNAME_SIZE];

 		s->s_flags = flags;
 		strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
 		error = btrfs_fill_super(s, fs_devices, data,
 					 flags & MS_SILENT ? 1 : 0);
 		if (error) {
 			deactivate_locked_super(s);
 			goto error_free_subvol_name;
 		}

 		btrfs_sb(s)->fs_info->bdev_holder = fs_type;
 		s->s_flags |= MS_ACTIVE;
 	}

 	if (!strcmp(subvol_name, "."))
 		root = dget(s->s_root);
 	else {
 		mutex_lock(&s->s_root->d_inode->i_mutex);
 		root = lookup_one_len(subvol_name, s->s_root,
 				      strlen(subvol_name));
 		mutex_unlock(&s->s_root->d_inode->i_mutex);

 		if (IS_ERR(root)) {
 			deactivate_locked_super(s);
 			error = PTR_ERR(root);
 			goto error_free_subvol_name;
 		}
 		if (!root->d_inode) {
 			dput(root);
 			deactivate_locked_super(s);
 			error = -ENXIO;
 			goto error_free_subvol_name;
 		}
 	}

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

 	kfree(subvol_name);
 	return 0;

 error_s:
 	error = PTR_ERR(s);
 error_close_devices:
 	btrfs_close_devices(fs_devices);
 error_free_subvol_name:
 	kfree(subvol_name);
 	return error;
 }

 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
 {
 	struct btrfs_root *root = btrfs_sb(sb);
 	int ret;

 	ret = btrfs_parse_options(root, data);
 	if (ret)
 		return -EINVAL;

 	if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
 		return 0;

 	if (*flags & MS_RDONLY) {
 		sb->s_flags |= MS_RDONLY;

 		ret =  btrfs_commit_super(root);
 		WARN_ON(ret);
 	} else {
 		if (root->fs_info->fs_devices->rw_devices == 0)
 			return -EACCES;

 		if (btrfs_super_log_root(&root->fs_info->super_copy) != 0)
 			return -EINVAL;

 		/* recover relocation */
 		ret = btrfs_recover_relocation(root);
 		WARN_ON(ret);

 		ret = btrfs_cleanup_fs_roots(root->fs_info);
 		WARN_ON(ret);

 		sb->s_flags &= ~MS_RDONLY;
 	}

 	return 0;
 }

 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;
 	__be32 *fsid = (__be32 *)root->fs_info->fsid;

 	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;

 	/* We treat it as constant endianness (it doesn't matter _which_)
 	   because we want the fsid to come out the same whether mounted
 	   on a big-endian or little-endian host */
 	buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
 	buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
 	/* Mask in the root object ID too, to disambiguate subvols */
 	buf->f_fsid.val[0] ^= BTRFS_I(dentry->d_inode)->root->objectid >> 32;
 	buf->f_fsid.val[1] ^= BTRFS_I(dentry->d_inode)->root->objectid;

 	return 0;
 }

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

 /*
  * used by btrfsctl to scan devices when no FS is mounted
  */
 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
 				unsigned long arg)
 {
 	struct btrfs_ioctl_vol_args *vol;
 	struct btrfs_fs_devices *fs_devices;
 	int ret = -ENOTTY;

 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;

 	vol = memdup_user((void __user *)arg, sizeof(*vol));
 	if (IS_ERR(vol))
 		return PTR_ERR(vol);

 	switch (cmd) {
 	case BTRFS_IOC_SCAN_DEV:
 		ret = btrfs_scan_one_device(vol->name, FMODE_READ,
 					    &btrfs_fs_type, &fs_devices);
 		break;
 	}

 	kfree(vol);
 	return ret;
 }

 static int btrfs_freeze(struct super_block *sb)
 {
 	struct btrfs_root *root = btrfs_sb(sb);
 	mutex_lock(&root->fs_info->transaction_kthread_mutex);
 	mutex_lock(&root->fs_info->cleaner_mutex);
 	return 0;
 }

 static int btrfs_unfreeze(struct super_block *sb)
 {
 	struct btrfs_root *root = btrfs_sb(sb);
 	mutex_unlock(&root->fs_info->cleaner_mutex);
 	mutex_unlock(&root->fs_info->transaction_kthread_mutex);
 	return 0;
 }

 static const struct super_operations btrfs_super_ops = {
 	.drop_inode	= btrfs_drop_inode,
 	.delete_inode	= btrfs_delete_inode,
 	.put_super	= btrfs_put_super,
 	.sync_fs	= btrfs_sync_fs,
 	.show_options	= btrfs_show_options,
 	.write_inode	= btrfs_write_inode,
 	.dirty_inode	= btrfs_dirty_inode,
 	.alloc_inode	= btrfs_alloc_inode,
 	.destroy_inode	= btrfs_destroy_inode,
 	.statfs		= btrfs_statfs,
 	.remount_fs	= btrfs_remount,
 	.freeze_fs	= btrfs_freeze,
 	.unfreeze_fs	= btrfs_unfreeze,
 };

 static const struct file_operations btrfs_ctl_fops = {
 	.unlocked_ioctl	 = btrfs_control_ioctl,
 	.compat_ioctl = btrfs_control_ioctl,
 	.owner	 = THIS_MODULE,
 };

 static struct miscdevice btrfs_misc = {
 	.minor		= MISC_DYNAMIC_MINOR,
 	.name		= "btrfs-control",
 	.fops		= &btrfs_ctl_fops
 };

 static int btrfs_interface_init(void)
 {
 	return misc_register(&btrfs_misc);
 }

 static void btrfs_interface_exit(void)
 {
 	if (misc_deregister(&btrfs_misc) < 0)
 		printk(KERN_INFO "misc_deregister failed for control device");
 }

 static int __init init_btrfs_fs(void)
 {
 	int err;

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

 	err = btrfs_init_cachep();
 	if (err)
 		goto free_sysfs;

 	err = extent_io_init();
 	if (err)
 		goto free_cachep;

 	err = extent_map_init();
 	if (err)
 		goto free_extent_io;

 	err = btrfs_interface_init();
 	if (err)
 		goto free_extent_map;

 	err = register_filesystem(&btrfs_fs_type);
 	if (err)
 		goto unregister_ioctl;

 	printk(KERN_INFO "%s loaded\n", BTRFS_BUILD_VERSION);
 	return 0;

 unregister_ioctl:
 	btrfs_interface_exit();
 free_extent_map:
 	extent_map_exit();
 free_extent_io:
 	extent_io_exit();
 free_cachep:
 	btrfs_destroy_cachep();
 free_sysfs:
 	btrfs_exit_sysfs();
 	return err;
 }

 static void __exit exit_btrfs_fs(void)
 {
 	btrfs_destroy_cachep();
 	extent_map_exit();
 	extent_io_exit();
 	btrfs_interface_exit();
 	unregister_filesystem(&btrfs_fs_type);
 	btrfs_exit_sysfs();
 	btrfs_cleanup_fs_uuids();
 	btrfs_zlib_exit();
 }

 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/seq_file.h>
	#include <linux/string.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 <linux/miscdevice.h>
	#include <linux/magic.h>
	#include "compat.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"
	#include "volumes.h"
	#include "version.h"
	#include "export.h"
	#include "compression.h"

	static const struct super_operations btrfs_super_ops;

	static void btrfs_put_super(struct super_block *sb)
	{
	struct btrfs_root *root = btrfs_sb(sb);
	int ret;

	ret = close_ctree(root);
	sb->s_fs_info = NULL;
	}

	enum {
	Opt_degraded, Opt_subvol, Opt_device, Opt_nodatasum, Opt_nodatacow,
	Opt_max_extent, Opt_max_inline, Opt_alloc_start, Opt_nobarrier,
	Opt_ssd, Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl,
	Opt_compress, Opt_notreelog, Opt_ratio, Opt_flushoncommit,
	Opt_discard, Opt_err,
	};

	static match_table_t tokens = {
	{Opt_degraded, "degraded"},
	{Opt_subvol, "subvol=%s"},
	{Opt_device, "device=%s"},
	{Opt_nodatasum, "nodatasum"},
	{Opt_nodatacow, "nodatacow"},
	{Opt_nobarrier, "nobarrier"},
	{Opt_max_extent, "max_extent=%s"},
	{Opt_max_inline, "max_inline=%s"},
	{Opt_alloc_start, "alloc_start=%s"},
	{Opt_thread_pool, "thread_pool=%d"},
	{Opt_compress, "compress"},
	{Opt_ssd, "ssd"},
	{Opt_ssd_spread, "ssd_spread"},
	{Opt_nossd, "nossd"},
	{Opt_noacl, "noacl"},
	{Opt_notreelog, "notreelog"},
	{Opt_flushoncommit, "flushoncommit"},
	{Opt_ratio, "metadata_ratio=%d"},
	{Opt_discard, "discard"},
	{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;
	}

	/*
	* Regular mount options parser. Everything that is needed only when
	* reading in a new superblock is parsed here.
	*/
	int btrfs_parse_options(struct btrfs_root root, char options)
	{
	struct btrfs_fs_info *info = root->fs_info;
	substring_t args[MAX_OPT_ARGS];
	char p, num;
	int intarg;
	int ret = 0;

	if (!options)
	return 0;

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


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

	token = match_token(p, tokens, args);
	switch (token) {
	case Opt_degraded:
	printk(KERN_INFO "btrfs: allowing degraded mounts\n");
	btrfs_set_opt(info->mount_opt, DEGRADED);
	break;
	case Opt_subvol:
	case Opt_device:
	/*
	* These are parsed by btrfs_parse_early_options
	* and can be happily ignored here.
	*/
	break;
	case Opt_nodatasum:
	printk(KERN_INFO "btrfs: setting nodatasum\n");
	btrfs_set_opt(info->mount_opt, NODATASUM);
	break;
	case Opt_nodatacow:
	printk(KERN_INFO "btrfs: setting nodatacow\n");
	btrfs_set_opt(info->mount_opt, NODATACOW);
	btrfs_set_opt(info->mount_opt, NODATASUM);
	break;
	case Opt_compress:
	printk(KERN_INFO "btrfs: use compression\n");
	btrfs_set_opt(info->mount_opt, COMPRESS);
	break;
	case Opt_ssd:
	printk(KERN_INFO "btrfs: use ssd allocation scheme\n");
	btrfs_set_opt(info->mount_opt, SSD);
	break;
	case Opt_ssd_spread:
	printk(KERN_INFO "btrfs: use spread ssd "
	"allocation scheme\n");
	btrfs_set_opt(info->mount_opt, SSD);
	btrfs_set_opt(info->mount_opt, SSD_SPREAD);
	break;
	case Opt_nossd:
	printk(KERN_INFO "btrfs: not using ssd allocation "
	"scheme\n");
	btrfs_set_opt(info->mount_opt, NOSSD);
	btrfs_clear_opt(info->mount_opt, SSD);
	btrfs_clear_opt(info->mount_opt, SSD_SPREAD);
	break;
	case Opt_nobarrier:
	printk(KERN_INFO "btrfs: turning off barriers\n");
	btrfs_set_opt(info->mount_opt, NOBARRIER);
	break;
	case Opt_thread_pool:
	intarg = 0;
	match_int(&args[0], &intarg);
	if (intarg) {
	info->thread_pool_size = intarg;
	printk(KERN_INFO "btrfs: thread pool %d\n",
	info->thread_pool_size);
	}
	break;
	case Opt_max_extent:
	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(KERN_INFO "btrfs: max_extent at %llu\n",
	(unsigned long long)info->max_extent);
	}
	break;
	case Opt_max_inline:
	num = match_strdup(&args[0]);
	if (num) {
	info->max_inline = btrfs_parse_size(num);
	kfree(num);

	if (info->max_inline) {
	info->max_inline = max_t(u64,
	info->max_inline,
	root->sectorsize);
	}
	printk(KERN_INFO "btrfs: max_inline at %llu\n",
	(unsigned long long)info->max_inline);
	}
	break;
	case Opt_alloc_start:
	num = match_strdup(&args[0]);
	if (num) {
	info->alloc_start = btrfs_parse_size(num);
	kfree(num);
	printk(KERN_INFO
	"btrfs: allocations start at %llu\n",
	(unsigned long long)info->alloc_start);
	}
	break;
	case Opt_noacl:
	root->fs_info->sb->s_flags &= ~MS_POSIXACL;
	break;
	case Opt_notreelog:
	printk(KERN_INFO "btrfs: disabling tree log\n");
	btrfs_set_opt(info->mount_opt, NOTREELOG);
	break;
	case Opt_flushoncommit:
	printk(KERN_INFO "btrfs: turning on flush-on-commit\n");
	btrfs_set_opt(info->mount_opt, FLUSHONCOMMIT);
	break;
	case Opt_ratio:
	intarg = 0;
	match_int(&args[0], &intarg);
	if (intarg) {
	info->metadata_ratio = intarg;
	printk(KERN_INFO "btrfs: metadata ratio %d\n",
	info->metadata_ratio);
	}
	break;
	case Opt_discard:
	btrfs_set_opt(info->mount_opt, DISCARD);
	break;
	case Opt_err:
	printk(KERN_INFO "btrfs: unrecognized mount option "
	"'%s'\n", p);
	ret = -EINVAL;
	goto out;
	default:
	break;
	}
	}
	out:
	kfree(options);
	return ret;
	}

	/*
	* Parse mount options that are required early in the mount process.
	*
	* All other options will be parsed on much later in the mount process and
	* only when we need to allocate a new super block.
	*/
	static int btrfs_parse_early_options(const char *options, fmode_t flags,
	void holder, char *subvol_name,
	struct btrfs_fs_devices **fs_devices)
	{
	substring_t args[MAX_OPT_ARGS];
	char opts, p;
	int error = 0;

	if (!options)
	goto out;

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

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

	token = match_token(p, tokens, args);
	switch (token) {
	case Opt_subvol:
	*subvol_name = match_strdup(&args[0]);
	break;
	case Opt_device:
	error = btrfs_scan_one_device(match_strdup(&args[0]),
	flags, holder, fs_devices);
	if (error)
	goto out_free_opts;
	break;
	default:
	break;
	}
	}

	out_free_opts:
	kfree(opts);
	out:
	/*
	* If no subvolume name is specified we use the default one. Allocate
	* a copy of the string "." here so that code later in the
	* mount path doesn't care if it's the default volume or another one.
	*/
	if (!*subvol_name) {
	*subvol_name = kstrdup(".", GFP_KERNEL);
	if (!*subvol_name)
	return -ENOMEM;
	}
	return error;
	}

	static int btrfs_fill_super(struct super_block *sb,
	struct btrfs_fs_devices *fs_devices,
	void *data, int silent)
	{
	struct inode *inode;
	struct dentry *root_dentry;
	struct btrfs_super_block *disk_super;
	struct btrfs_root *tree_root;
	struct btrfs_key key;
	int err;

	sb->s_maxbytes = MAX_LFS_FILESIZE;
	sb->s_magic = BTRFS_SUPER_MAGIC;
	sb->s_op = &btrfs_super_ops;
	sb->s_export_op = &btrfs_export_ops;
	sb->s_xattr = btrfs_xattr_handlers;
	sb->s_time_gran = 1;
	#ifdef CONFIG_BTRFS_FS_POSIX_ACL
	sb->s_flags \|= MS_POSIXACL;
	#endif

	tree_root = open_ctree(sb, fs_devices, (char *)data);

	if (IS_ERR(tree_root)) {
	printk("btrfs: open_ctree failed\n");
	return PTR_ERR(tree_root);
	}
	sb->s_fs_info = tree_root;
	disk_super = &tree_root->fs_info->super_copy;

	key.objectid = BTRFS_FIRST_FREE_OBJECTID;
	key.type = BTRFS_INODE_ITEM_KEY;
	key.offset = 0;
	inode = btrfs_iget(sb, &key, tree_root->fs_info->fs_root);
	if (IS_ERR(inode)) {
	err = PTR_ERR(inode);
	goto fail_close;
	}

	root_dentry = d_alloc_root(inode);
	if (!root_dentry) {
	iput(inode);
	err = -ENOMEM;
	goto fail_close;
	}
	#if 0
	/* this does the super kobj at the same time */
	err = btrfs_sysfs_add_super(tree_root->fs_info);
	if (err)
	goto fail_close;
	#endif

	sb->s_root = root_dentry;

	save_mount_options(sb, data);
	return 0;

	fail_close:
	close_ctree(tree_root);
	return err;
	}

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

	if (!wait) {
	filemap_flush(root->fs_info->btree_inode->i_mapping);
	return 0;
	}

	btrfs_start_delalloc_inodes(root, 0);
	btrfs_wait_ordered_extents(root, 0, 0);

	trans = btrfs_start_transaction(root, 1);
	ret = btrfs_commit_transaction(trans, root);
	return ret;
	}

	static int btrfs_show_options(struct seq_file seq, struct vfsmount vfs)
	{
	struct btrfs_root *root = btrfs_sb(vfs->mnt_sb);
	struct btrfs_fs_info *info = root->fs_info;

	if (btrfs_test_opt(root, DEGRADED))
	seq_puts(seq, ",degraded");
	if (btrfs_test_opt(root, NODATASUM))
	seq_puts(seq, ",nodatasum");
	if (btrfs_test_opt(root, NODATACOW))
	seq_puts(seq, ",nodatacow");
	if (btrfs_test_opt(root, NOBARRIER))
	seq_puts(seq, ",nobarrier");
	if (info->max_extent != (u64)-1)
	seq_printf(seq, ",max_extent=%llu",
	(unsigned long long)info->max_extent);
	if (info->max_inline != 8192 * 1024)
	seq_printf(seq, ",max_inline=%llu",
	(unsigned long long)info->max_inline);
	if (info->alloc_start != 0)
	seq_printf(seq, ",alloc_start=%llu",
	(unsigned long long)info->alloc_start);
	if (info->thread_pool_size != min_t(unsigned long,
	num_online_cpus() + 2, 8))
	seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
	if (btrfs_test_opt(root, COMPRESS))
	seq_puts(seq, ",compress");
	if (btrfs_test_opt(root, NOSSD))
	seq_puts(seq, ",nossd");
	if (btrfs_test_opt(root, SSD_SPREAD))
	seq_puts(seq, ",ssd_spread");
	else if (btrfs_test_opt(root, SSD))
	seq_puts(seq, ",ssd");
	if (btrfs_test_opt(root, NOTREELOG))
	seq_puts(seq, ",notreelog");
	if (btrfs_test_opt(root, FLUSHONCOMMIT))
	seq_puts(seq, ",flushoncommit");
	if (btrfs_test_opt(root, DISCARD))
	seq_puts(seq, ",discard");
	if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
	seq_puts(seq, ",noacl");
	return 0;
	}

	static int btrfs_test_super(struct super_block s, void data)
	{
	struct btrfs_fs_devices *test_fs_devices = data;
	struct btrfs_root *root = btrfs_sb(s);

	return root->fs_info->fs_devices == test_fs_devices;
	}

	/*
	* Find a superblock for the given device / mount point.
	*
	* Note: This is based on get_sb_bdev from fs/super.c with a few additions
	* for multiple device setup. Make sure to keep it in sync.
	*/
	static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
	const char dev_name, void data, struct vfsmount *mnt)
	{
	char *subvol_name = NULL;
	struct block_device *bdev = NULL;
	struct super_block *s;
	struct dentry *root;
	struct btrfs_fs_devices *fs_devices = NULL;
	fmode_t mode = FMODE_READ;
	int error = 0;

	if (!(flags & MS_RDONLY))
	mode \|= FMODE_WRITE;

	error = btrfs_parse_early_options(data, mode, fs_type,
	&subvol_name, &fs_devices);
	if (error)
	return error;

	error = btrfs_scan_one_device(dev_name, mode, fs_type, &fs_devices);
	if (error)
	goto error_free_subvol_name;

	error = btrfs_open_devices(fs_devices, mode, fs_type);
	if (error)
	goto error_free_subvol_name;

	if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
	error = -EACCES;
	goto error_close_devices;
	}

	bdev = fs_devices->latest_bdev;
	s = sget(fs_type, btrfs_test_super, set_anon_super, fs_devices);
	if (IS_ERR(s))
	goto error_s;

	if (s->s_root) {
	if ((flags ^ s->s_flags) & MS_RDONLY) {
	deactivate_locked_super(s);
	error = -EBUSY;
	goto error_close_devices;
	}

	btrfs_close_devices(fs_devices);
	} else {
	char b[BDEVNAME_SIZE];

	s->s_flags = flags;
	strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
	error = btrfs_fill_super(s, fs_devices, data,
	flags & MS_SILENT ? 1 : 0);
	if (error) {
	deactivate_locked_super(s);
	goto error_free_subvol_name;
	}

	btrfs_sb(s)->fs_info->bdev_holder = fs_type;
	s->s_flags \|= MS_ACTIVE;
	}

	if (!strcmp(subvol_name, "."))
	root = dget(s->s_root);
	else {
	mutex_lock(&s->s_root->d_inode->i_mutex);
	root = lookup_one_len(subvol_name, s->s_root,
	strlen(subvol_name));
	mutex_unlock(&s->s_root->d_inode->i_mutex);

	if (IS_ERR(root)) {
	deactivate_locked_super(s);
	error = PTR_ERR(root);
	goto error_free_subvol_name;
	}
	if (!root->d_inode) {
	dput(root);
	deactivate_locked_super(s);
	error = -ENXIO;
	goto error_free_subvol_name;
	}
	}

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

	kfree(subvol_name);
	return 0;

	error_s:
	error = PTR_ERR(s);
	error_close_devices:
	btrfs_close_devices(fs_devices);
	error_free_subvol_name:
	kfree(subvol_name);
	return error;
	}

	static int btrfs_remount(struct super_block sb, int flags, char *data)
	{
	struct btrfs_root *root = btrfs_sb(sb);
	int ret;

	ret = btrfs_parse_options(root, data);
	if (ret)
	return -EINVAL;

	if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
	return 0;

	if (*flags & MS_RDONLY) {
	sb->s_flags \|= MS_RDONLY;

	ret = btrfs_commit_super(root);
	WARN_ON(ret);
	} else {
	if (root->fs_info->fs_devices->rw_devices == 0)
	return -EACCES;

	if (btrfs_super_log_root(&root->fs_info->super_copy) != 0)
	return -EINVAL;

	/* recover relocation */
	ret = btrfs_recover_relocation(root);
	WARN_ON(ret);

	ret = btrfs_cleanup_fs_roots(root->fs_info);
	WARN_ON(ret);

	sb->s_flags &= ~MS_RDONLY;
	}

	return 0;
	}

	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;
	__be32 fsid = (__be32 )root->fs_info->fsid;

	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;

	/* We treat it as constant endianness (it doesn't matter _which_)
	because we want the fsid to come out the same whether mounted
	on a big-endian or little-endian host */
	buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
	buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
	/* Mask in the root object ID too, to disambiguate subvols */
	buf->f_fsid.val[0] ^= BTRFS_I(dentry->d_inode)->root->objectid >> 32;
	buf->f_fsid.val[1] ^= BTRFS_I(dentry->d_inode)->root->objectid;

	return 0;
	}

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

	/*
	* used by btrfsctl to scan devices when no FS is mounted
	*/
	static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
	unsigned long arg)
	{
	struct btrfs_ioctl_vol_args *vol;
	struct btrfs_fs_devices *fs_devices;
	int ret = -ENOTTY;

	if (!capable(CAP_SYS_ADMIN))
	return -EPERM;

	vol = memdup_user((void __user )arg, sizeof(vol));
	if (IS_ERR(vol))
	return PTR_ERR(vol);

	switch (cmd) {
	case BTRFS_IOC_SCAN_DEV:
	ret = btrfs_scan_one_device(vol->name, FMODE_READ,
	&btrfs_fs_type, &fs_devices);
	break;
	}

	kfree(vol);
	return ret;
	}

	static int btrfs_freeze(struct super_block *sb)
	{
	struct btrfs_root *root = btrfs_sb(sb);
	mutex_lock(&root->fs_info->transaction_kthread_mutex);
	mutex_lock(&root->fs_info->cleaner_mutex);
	return 0;
	}

	static int btrfs_unfreeze(struct super_block *sb)
	{
	struct btrfs_root *root = btrfs_sb(sb);
	mutex_unlock(&root->fs_info->cleaner_mutex);
	mutex_unlock(&root->fs_info->transaction_kthread_mutex);
	return 0;
	}

	static const struct super_operations btrfs_super_ops = {
	.drop_inode = btrfs_drop_inode,
	.delete_inode = btrfs_delete_inode,
	.put_super = btrfs_put_super,
	.sync_fs = btrfs_sync_fs,
	.show_options = btrfs_show_options,
	.write_inode = btrfs_write_inode,
	.dirty_inode = btrfs_dirty_inode,
	.alloc_inode = btrfs_alloc_inode,
	.destroy_inode = btrfs_destroy_inode,
	.statfs = btrfs_statfs,
	.remount_fs = btrfs_remount,
	.freeze_fs = btrfs_freeze,
	.unfreeze_fs = btrfs_unfreeze,
	};

	static const struct file_operations btrfs_ctl_fops = {
	.unlocked_ioctl = btrfs_control_ioctl,
	.compat_ioctl = btrfs_control_ioctl,
	.owner = THIS_MODULE,
	};

	static struct miscdevice btrfs_misc = {
	.minor = MISC_DYNAMIC_MINOR,
	.name = "btrfs-control",
	.fops = &btrfs_ctl_fops
	};

	static int btrfs_interface_init(void)
	{
	return misc_register(&btrfs_misc);
	}

	static void btrfs_interface_exit(void)
	{
	if (misc_deregister(&btrfs_misc) < 0)
	printk(KERN_INFO "misc_deregister failed for control device");
	}

	static int __init init_btrfs_fs(void)
	{
	int err;

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

	err = btrfs_init_cachep();
	if (err)
	goto free_sysfs;

	err = extent_io_init();
	if (err)
	goto free_cachep;

	err = extent_map_init();
	if (err)
	goto free_extent_io;

	err = btrfs_interface_init();
	if (err)
	goto free_extent_map;

	err = register_filesystem(&btrfs_fs_type);
	if (err)
	goto unregister_ioctl;

	printk(KERN_INFO "%s loaded\n", BTRFS_BUILD_VERSION);
	return 0;

	unregister_ioctl:
	btrfs_interface_exit();
	free_extent_map:
	extent_map_exit();
	free_extent_io:
	extent_io_exit();
	free_cachep:
	btrfs_destroy_cachep();
	free_sysfs:
	btrfs_exit_sysfs();
	return err;
	}

	static void __exit exit_btrfs_fs(void)
	{
	btrfs_destroy_cachep();
	extent_map_exit();
	extent_io_exit();
	btrfs_interface_exit();
	unregister_filesystem(&btrfs_fs_type);
	btrfs_exit_sysfs();
	btrfs_cleanup_fs_uuids();
	btrfs_zlib_exit();
	}

	module_init(init_btrfs_fs)
	module_exit(exit_btrfs_fs)

	MODULE_LICENSE("GPL");