Re: [PATCH 05/21] Btrfs: add basic restriper infrastructure

[Arne Jansen <sensille@gmx.net>]

On 23.08.2011 22:01, Ilya Dryomov wrote:
> Add basic restriper infrastructure: ioctl to start restripe, all
> restripe ioctl data structures, add data structure for tracking
> restriper's state to fs_info.  Duplicate balancing code for restriper,
> btrfs_balance() will be removed when restriper is implemented.
> 
> Explicitly disallow any volume operations when restriper is running.
> (previously this restriction relied on volume_mutex being held during
> the execution of any volume operation)
> 
> Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
> ---
>  fs/btrfs/ctree.h   |    5 +
>  fs/btrfs/disk-io.c |    4 +
>  fs/btrfs/ioctl.c   |  107 ++++++++++++++++++++++----
>  fs/btrfs/ioctl.h   |   37 +++++++++
>  fs/btrfs/volumes.c |  219 ++++++++++++++++++++++++++++++++++++++++++++++++++--
>  fs/btrfs/volumes.h |   18 ++++
>  6 files changed, 369 insertions(+), 21 deletions(-)
> 
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index 5b00eb8..65d7562 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -895,6 +895,7 @@ struct btrfs_block_group_cache {
>  };
>  
>  struct reloc_control;
> +struct restripe_control;
>  struct btrfs_device;
>  struct btrfs_fs_devices;
>  struct btrfs_delayed_root;
> @@ -1116,6 +1117,10 @@ struct btrfs_fs_info {
>  	u64 avail_metadata_alloc_bits;
>  	u64 avail_system_alloc_bits;
>  
> +	spinlock_t restripe_lock;
> +	struct mutex restripe_mutex;
> +	struct restripe_control *restripe_ctl;
> +

Can you please add some comments on the usage of the locks and
how to protect the restripe_ctl pointer and the access to its
data structures?

>  	unsigned data_chunk_allocations;
>  	unsigned metadata_ratio;
>  
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index 46d0412..fa2301b 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -1700,6 +1700,10 @@ struct btrfs_root *open_ctree(struct super_block *sb,
>  	init_rwsem(&fs_info->scrub_super_lock);
>  	fs_info->scrub_workers_refcnt = 0;
>  
> +	spin_lock_init(&fs_info->restripe_lock);
> +	mutex_init(&fs_info->restripe_mutex);
> +	fs_info->restripe_ctl = NULL;
> +
>  	sb->s_blocksize = 4096;
>  	sb->s_blocksize_bits = blksize_bits(4096);
>  	sb->s_bdi = &fs_info->bdi;
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 970977a..9dfc686 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -1165,13 +1165,21 @@ static noinline int btrfs_ioctl_resize(struct btrfs_root *root,
>  	if (!capable(CAP_SYS_ADMIN))
>  		return -EPERM;
>  
> +	mutex_lock(&root->fs_info->volume_mutex);
> +	if (root->fs_info->restripe_ctl) {
> +		printk(KERN_INFO "btrfs: restripe in progress\n");
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
>  	vol_args = memdup_user(arg, sizeof(*vol_args));
> -	if (IS_ERR(vol_args))
> -		return PTR_ERR(vol_args);
> +	if (IS_ERR(vol_args)) {
> +		ret = PTR_ERR(vol_args);
> +		goto out;
> +	}
>  
>  	vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
>  
> -	mutex_lock(&root->fs_info->volume_mutex);
>  	sizestr = vol_args->name;
>  	devstr = strchr(sizestr, ':');
>  	if (devstr) {
> @@ -1188,7 +1196,7 @@ static noinline int btrfs_ioctl_resize(struct btrfs_root *root,
>  		printk(KERN_INFO "resizer unable to find device %llu\n",
>  		       (unsigned long long)devid);
>  		ret = -EINVAL;
> -		goto out_unlock;
> +		goto out_free;
>  	}
>  	if (!strcmp(sizestr, "max"))
>  		new_size = device->bdev->bd_inode->i_size;
> @@ -1203,7 +1211,7 @@ static noinline int btrfs_ioctl_resize(struct btrfs_root *root,
>  		new_size = memparse(sizestr, NULL);
>  		if (new_size == 0) {
>  			ret = -EINVAL;
> -			goto out_unlock;
> +			goto out_free;
>  		}
>  	}
>  
> @@ -1212,7 +1220,7 @@ static noinline int btrfs_ioctl_resize(struct btrfs_root *root,
>  	if (mod < 0) {
>  		if (new_size > old_size) {
>  			ret = -EINVAL;
> -			goto out_unlock;
> +			goto out_free;
>  		}
>  		new_size = old_size - new_size;
>  	} else if (mod > 0) {
> @@ -1221,11 +1229,11 @@ static noinline int btrfs_ioctl_resize(struct btrfs_root *root,
>  
>  	if (new_size < 256 * 1024 * 1024) {
>  		ret = -EINVAL;
> -		goto out_unlock;
> +		goto out_free;
>  	}
>  	if (new_size > device->bdev->bd_inode->i_size) {
>  		ret = -EFBIG;
> -		goto out_unlock;
> +		goto out_free;
>  	}
>  
>  	do_div(new_size, root->sectorsize);
> @@ -1238,7 +1246,7 @@ static noinline int btrfs_ioctl_resize(struct btrfs_root *root,
>  		trans = btrfs_start_transaction(root, 0);
>  		if (IS_ERR(trans)) {
>  			ret = PTR_ERR(trans);
> -			goto out_unlock;
> +			goto out_free;
>  		}
>  		ret = btrfs_grow_device(trans, device, new_size);
>  		btrfs_commit_transaction(trans, root);
> @@ -1246,9 +1254,10 @@ static noinline int btrfs_ioctl_resize(struct btrfs_root *root,
>  		ret = btrfs_shrink_device(device, new_size);
>  	}
>  
> -out_unlock:
> -	mutex_unlock(&root->fs_info->volume_mutex);
> +out_free:
>  	kfree(vol_args);
> +out:
> +	mutex_unlock(&root->fs_info->volume_mutex);
>  	return ret;
>  }
>  
> @@ -2014,14 +2023,25 @@ static long btrfs_ioctl_add_dev(struct btrfs_root *root, void __user *arg)
>  	if (!capable(CAP_SYS_ADMIN))
>  		return -EPERM;
>  
> +	mutex_lock(&root->fs_info->volume_mutex);
> +	if (root->fs_info->restripe_ctl) {
> +		printk(KERN_INFO "btrfs: restripe in progress\n");
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
>  	vol_args = memdup_user(arg, sizeof(*vol_args));
> -	if (IS_ERR(vol_args))
> -		return PTR_ERR(vol_args);
> +	if (IS_ERR(vol_args)) {
> +		ret = PTR_ERR(vol_args);
> +		goto out;
> +	}
>  
>  	vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
>  	ret = btrfs_init_new_device(root, vol_args->name);
>  
>  	kfree(vol_args);
> +out:
> +	mutex_unlock(&root->fs_info->volume_mutex);
>  	return ret;
>  }
>  
> @@ -2036,14 +2056,25 @@ static long btrfs_ioctl_rm_dev(struct btrfs_root *root, void __user *arg)
>  	if (root->fs_info->sb->s_flags & MS_RDONLY)
>  		return -EROFS;
>  
> +	mutex_lock(&root->fs_info->volume_mutex);
> +	if (root->fs_info->restripe_ctl) {
> +		printk(KERN_INFO "btrfs: restripe in progress\n");
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
>  	vol_args = memdup_user(arg, sizeof(*vol_args));
> -	if (IS_ERR(vol_args))
> -		return PTR_ERR(vol_args);
> +	if (IS_ERR(vol_args)) {
> +		ret = PTR_ERR(vol_args);
> +		goto out;
> +	}
>  
>  	vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
>  	ret = btrfs_rm_device(root, vol_args->name);
>  
>  	kfree(vol_args);
> +out:
> +	mutex_unlock(&root->fs_info->volume_mutex);
>  	return ret;
>  }
>  
> @@ -2833,6 +2864,50 @@ static long btrfs_ioctl_scrub_progress(struct btrfs_root *root,
>  	return ret;
>  }
>  
> +static long btrfs_ioctl_restripe(struct btrfs_root *root, void __user *arg)
> +{
> +	struct btrfs_ioctl_restripe_args *rargs;
> +	struct btrfs_fs_info *fs_info = root->fs_info;
> +	struct restripe_control *rctl;
> +	int ret;
> +
> +	if (!capable(CAP_SYS_ADMIN))
> +		return -EPERM;
> +
> +	if (fs_info->sb->s_flags & MS_RDONLY)
> +		return -EROFS;
> +
> +	mutex_lock(&fs_info->restripe_mutex);
> +
> +	rargs = memdup_user(arg, sizeof(*rargs));
> +	if (IS_ERR(rargs)) {
> +		ret = PTR_ERR(rargs);
> +		goto out;
> +	}
> +
> +	rctl = kzalloc(sizeof(*rctl), GFP_NOFS);
> +	if (!rctl) {
> +		kfree(rargs);
> +		ret = -ENOMEM;
> +		goto out;
> +	}
> +
> +	rctl->fs_info = fs_info;
> +	rctl->flags = rargs->flags;
> +
> +	memcpy(&rctl->data, &rargs->data, sizeof(rctl->data));
> +	memcpy(&rctl->meta, &rargs->meta, sizeof(rctl->meta));
> +	memcpy(&rctl->sys, &rargs->sys, sizeof(rctl->sys));
> +
> +	ret = btrfs_restripe(rctl);
> +
> +	/* rctl freed in unset_restripe_control */
> +	kfree(rargs);
> +out:
> +	mutex_unlock(&fs_info->restripe_mutex);
> +	return ret;
> +}
> +
>  long btrfs_ioctl(struct file *file, unsigned int
>  		cmd, unsigned long arg)
>  {
> @@ -2905,6 +2980,8 @@ long btrfs_ioctl(struct file *file, unsigned int
>  		return btrfs_ioctl_scrub_cancel(root, argp);
>  	case BTRFS_IOC_SCRUB_PROGRESS:
>  		return btrfs_ioctl_scrub_progress(root, argp);
> +	case BTRFS_IOC_RESTRIPE:
> +		return btrfs_ioctl_restripe(root, argp);
>  	}
>  
>  	return -ENOTTY;
> diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
> index ad1ea78..798f1d4 100644
> --- a/fs/btrfs/ioctl.h
> +++ b/fs/btrfs/ioctl.h
> @@ -109,6 +109,41 @@ struct btrfs_ioctl_fs_info_args {
>  	__u64 reserved[124];			/* pad to 1k */
>  };
>  
> +struct btrfs_restripe_args {
> +	__u64 profiles;
> +	__u64 usage;
> +	__u64 devid;
> +	__u64 pstart;
> +	__u64 pend;
> +	__u64 vstart;
> +	__u64 vend;
> +
> +	__u64 target;
> +
> +	__u64 flags;
> +
> +	__u64 unused[8];
> +} __attribute__ ((__packed__));
> +
> +struct btrfs_restripe_progress {
> +	__u64 expected;
> +	__u64 considered;
> +	__u64 completed;
> +};
> +
> +struct btrfs_ioctl_restripe_args {
> +	__u64 flags;
> +	__u64 state;
> +
> +	struct btrfs_restripe_args data;
> +	struct btrfs_restripe_args sys;
> +	struct btrfs_restripe_args meta;
> +
> +	struct btrfs_restripe_progress stat;
> +
> +	__u64 unused[72]; /* pad to 1k */
> +};
> +
>  #define BTRFS_INO_LOOKUP_PATH_MAX 4080
>  struct btrfs_ioctl_ino_lookup_args {
>  	__u64 treeid;
> @@ -248,4 +283,6 @@ struct btrfs_ioctl_space_args {
>  				 struct btrfs_ioctl_dev_info_args)
>  #define BTRFS_IOC_FS_INFO _IOR(BTRFS_IOCTL_MAGIC, 31, \
>  			       struct btrfs_ioctl_fs_info_args)
> +#define BTRFS_IOC_RESTRIPE _IOW(BTRFS_IOCTL_MAGIC, 32, \
> +				struct btrfs_ioctl_restripe_args)
>  #endif
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index af4bf56..0e4a276 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -1262,7 +1262,6 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
>  	bool clear_super = false;
>  
>  	mutex_lock(&uuid_mutex);
> -	mutex_lock(&root->fs_info->volume_mutex);
>  
>  	all_avail = root->fs_info->avail_data_alloc_bits |
>  		root->fs_info->avail_system_alloc_bits |
> @@ -1427,7 +1426,6 @@ error_close:
>  	if (bdev)
>  		blkdev_put(bdev, FMODE_READ | FMODE_EXCL);
>  out:
> -	mutex_unlock(&root->fs_info->volume_mutex);
>  	mutex_unlock(&uuid_mutex);
>  	return ret;
>  error_undo:
> @@ -1604,7 +1602,6 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
>  	}
>  
>  	filemap_write_and_wait(bdev->bd_inode->i_mapping);
> -	mutex_lock(&root->fs_info->volume_mutex);
>  
>  	devices = &root->fs_info->fs_devices->devices;
>  	/*
> @@ -1728,8 +1725,7 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
>  		ret = btrfs_relocate_sys_chunks(root);
>  		BUG_ON(ret);
>  	}
> -out:
> -	mutex_unlock(&root->fs_info->volume_mutex);
> +
>  	return ret;
>  error:
>  	blkdev_put(bdev, FMODE_EXCL);
> @@ -1737,7 +1733,7 @@ error:
>  		mutex_unlock(&uuid_mutex);
>  		up_write(&sb->s_umount);
>  	}
> -	goto out;
> +	return ret;
>  }
>  
>  static noinline int btrfs_update_device(struct btrfs_trans_handle *trans,
> @@ -2155,6 +2151,217 @@ error:
>  }
>  
>  /*
> + * Should be called with both restripe and volume mutexes held to
> + * serialize other volume operations (add_dev/rm_dev/resize) wrt
> + * restriper.  Same goes for unset_restripe_control().
> + */
> +static void set_restripe_control(struct restripe_control *rctl)
> +{
> +	struct btrfs_fs_info *fs_info = rctl->fs_info;
> +
> +	spin_lock(&fs_info->restripe_lock);
> +	fs_info->restripe_ctl = rctl;
> +	spin_unlock(&fs_info->restripe_lock);
> +}
> +
> +static void unset_restripe_control(struct btrfs_fs_info *fs_info)
> +{
> +	struct restripe_control *rctl = fs_info->restripe_ctl;
> +
> +	spin_lock(&fs_info->restripe_lock);
> +	fs_info->restripe_ctl = NULL;
> +	spin_unlock(&fs_info->restripe_lock);
> +
> +	kfree(rctl);
> +}
> +
> +static int __btrfs_restripe(struct btrfs_root *dev_root)
> +{
> +	struct list_head *devices;
> +	struct btrfs_device *device;
> +	u64 old_size;
> +	u64 size_to_free;
> +	struct btrfs_root *chunk_root = dev_root->fs_info->chunk_root;
> +	struct btrfs_path *path;
> +	struct btrfs_key key;
> +	struct btrfs_key found_key;
> +	struct btrfs_trans_handle *trans;
> +	int ret;
> +	int enospc_errors = 0;
> +
> +	/* step one make some room on all the devices */
> +	devices = &dev_root->fs_info->fs_devices->devices;
> +	list_for_each_entry(device, devices, dev_list) {
> +		old_size = device->total_bytes;
> +		size_to_free = div_factor(old_size, 1);
> +		size_to_free = min(size_to_free, (u64)1 * 1024 * 1024);
> +		if (!device->writeable ||
> +		    device->total_bytes - device->bytes_used > size_to_free)
> +			continue;
> +
> +		ret = btrfs_shrink_device(device, old_size - size_to_free);
> +		if (ret == -ENOSPC)
> +			break;
> +		BUG_ON(ret);
> +
> +		trans = btrfs_start_transaction(dev_root, 0);
> +		BUG_ON(IS_ERR(trans));
> +
> +		ret = btrfs_grow_device(trans, device, old_size);
> +		BUG_ON(ret);
> +
> +		btrfs_end_transaction(trans, dev_root);
> +	}
> +
> +	/* step two, relocate all the chunks */
> +	path = btrfs_alloc_path();
> +	if (!path) {
> +		ret = -ENOMEM;
> +		goto error;
> +	}
> +
> +	key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
> +	key.offset = (u64)-1;
> +	key.type = BTRFS_CHUNK_ITEM_KEY;
> +
> +	while (1) {
> +		ret = btrfs_search_slot(NULL, chunk_root, &key, path, 0, 0);
> +		if (ret < 0)
> +			goto error;
> +
> +		/*
> +		 * this shouldn't happen, it means the last relocate
> +		 * failed
> +		 */
> +		if (ret == 0)
> +			BUG_ON(1); /* DIS - break ? */
> +
> +		ret = btrfs_previous_item(chunk_root, path, 0,
> +					  BTRFS_CHUNK_ITEM_KEY);
> +		if (ret)
> +			BUG_ON(1); /* DIS - break ? */
> +
> +		btrfs_item_key_to_cpu(path->nodes[0], &found_key,
> +				      path->slots[0]);
> +		if (found_key.objectid != key.objectid)
> +			break;
> +
> +		/* chunk zero is special */
> +		if (found_key.offset == 0)
> +			break;
> +
> +		btrfs_release_path(path);
> +		ret = btrfs_relocate_chunk(chunk_root,
> +					   chunk_root->root_key.objectid,
> +					   found_key.objectid,
> +					   found_key.offset);
> +		if (ret && ret != -ENOSPC)
> +			goto error;
> +		if (ret == -ENOSPC)
> +			enospc_errors++;
> +		key.offset = found_key.offset - 1;
> +	}
> +
> +error:
> +	btrfs_free_path(path);
> +	if (enospc_errors) {
> +		printk(KERN_INFO "btrfs: restripe finished with %d enospc "
> +		       "error(s)\n", enospc_errors);
> +		ret = -ENOSPC;
> +	}
> +
> +	return ret;
> +}
> +
> +/*
> + * Should be called with restripe_mutex held
> + */
> +int btrfs_restripe(struct restripe_control *rctl)
> +{
> +	struct btrfs_fs_info *fs_info = rctl->fs_info;
> +	u64 allowed;
> +	int ret;
> +
> +	mutex_lock(&fs_info->volume_mutex);
> +
> +	/*
> +	 * Profile changing sanity checks
> +	 */
> +	allowed = BTRFS_AVAIL_ALLOC_BIT_SINGLE;
> +	if (fs_info->fs_devices->num_devices == 1)
> +		allowed |= BTRFS_BLOCK_GROUP_DUP;
> +	else if (fs_info->fs_devices->num_devices < 4)
> +		allowed |= (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1);
> +	else
> +		allowed |= (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1 |
> +				BTRFS_BLOCK_GROUP_RAID10);
> +
> +	if (rctl->data.target & ~allowed) {
> +		printk(KERN_ERR "btrfs: unable to start restripe with target "
> +		       "data profile %llu\n",
> +		       (unsigned long long)rctl->data.target);
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +	if (rctl->sys.target & ~allowed) {
> +		printk(KERN_ERR "btrfs: unable to start restripe with target "
> +		       "system profile %llu\n",
> +		       (unsigned long long)rctl->sys.target);
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +	if (rctl->meta.target & ~allowed) {
> +		printk(KERN_ERR "btrfs: unable to start restripe with target "
> +		       "metadata profile %llu\n",
> +		       (unsigned long long)rctl->meta.target);
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
> +	if (rctl->data.target & BTRFS_BLOCK_GROUP_DUP) {
> +		printk(KERN_ERR "btrfs: dup for data is not allowed\n");
> +		ret = -EINVAL;
> +		goto out;
> +	}

It would be good to get these error messages somehow to the user,
or at least give the user a hint to look in dmesg.

> +
> +	/* allow to reduce meta or sys integrity only if force set */
> +	allowed = BTRFS_BLOCK_GROUP_DUP | BTRFS_BLOCK_GROUP_RAID1 |
> +			BTRFS_BLOCK_GROUP_RAID10;
> +	if (((rctl->sys.flags & BTRFS_RESTRIPE_ARGS_CONVERT) &&
> +	     (fs_info->avail_system_alloc_bits & allowed) &&
> +	     !(rctl->sys.target & allowed)) ||
> +	    ((rctl->meta.flags & BTRFS_RESTRIPE_ARGS_CONVERT) &&
> +	     (fs_info->avail_metadata_alloc_bits & allowed) &&
> +	     !(rctl->meta.target & allowed))) {
> +		if (rctl->flags & BTRFS_RESTRIPE_FORCE) {
> +			printk(KERN_INFO "btrfs: force reducing metadata "
> +			       "integrity\n");
> +		} else {
> +			printk(KERN_ERR "btrfs: can't reduce metadata "
> +			       "integrity\n");
> +			ret = -EINVAL;
> +			goto out;
> +		}
> +	}
> +
> +	set_restripe_control(rctl);
> +	mutex_unlock(&fs_info->volume_mutex);
> +
> +	ret = __btrfs_restripe(fs_info->dev_root);
> +
> +	mutex_lock(&fs_info->volume_mutex);
> +	unset_restripe_control(fs_info);
> +	mutex_unlock(&fs_info->volume_mutex);
> +
> +	return ret;
> +
> +out:
> +	mutex_unlock(&fs_info->volume_mutex);
> +	kfree(rctl);
> +	return ret;
> +}
> +
> +/*
>   * shrinking a device means finding all of the device extents past
>   * the new size, and then following the back refs to the chunks.
>   * The chunk relocation code actually frees the device extent
> diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
> index 6d866db..8804c5c 100644
> --- a/fs/btrfs/volumes.h
> +++ b/fs/btrfs/volumes.h
> @@ -168,6 +168,23 @@ struct map_lookup {
>  #define map_lookup_size(n) (sizeof(struct map_lookup) + \
>  			    (sizeof(struct btrfs_bio_stripe) * (n)))
>  
> +#define BTRFS_RESTRIPE_FORCE		(1ULL << 3)
> +
> +/*
> + * Profile changing flags
> + */
> +#define BTRFS_RESTRIPE_ARGS_CONVERT	(1ULL << 8)
> +
> +struct btrfs_restripe_args;
> +struct restripe_control {
> +	struct btrfs_fs_info *fs_info;
> +	u64 flags;
> +
> +	struct btrfs_restripe_args data;
> +	struct btrfs_restripe_args sys;
> +	struct btrfs_restripe_args meta;
> +};
> +
>  int btrfs_account_dev_extents_size(struct btrfs_device *device, u64 start,
>  				   u64 end, u64 *length);
>  
> @@ -211,6 +228,7 @@ struct btrfs_device *btrfs_find_device(struct btrfs_root *root, u64 devid,
>  int btrfs_shrink_device(struct btrfs_device *device, u64 new_size);
>  int btrfs_init_new_device(struct btrfs_root *root, char *path);
>  int btrfs_balance(struct btrfs_root *dev_root);
> +int btrfs_restripe(struct restripe_control *rctl);
>  int btrfs_chunk_readonly(struct btrfs_root *root, u64 chunk_offset);
>  int find_free_dev_extent(struct btrfs_trans_handle *trans,
>  			 struct btrfs_device *device, u64 num_bytes,