btrfs-progs/utils.c

/*
 * 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.
 */

#define _XOPEN_SOURCE 600
#define __USE_XOPEN2K
#include <stdio.h>
#include <stdlib.h>
#ifndef __CHECKER__
#include <sys/ioctl.h>
#include <sys/mount.h>
#endif
#include <sys/types.h>
#include <sys/stat.h>
#include <uuid/uuid.h>
#include <dirent.h>
#include <fcntl.h>
#include <unistd.h>
#include <mntent.h>
#include "kerncompat.h"
#include "radix-tree.h"
#include "ctree.h"
#include "disk-io.h"
#include "transaction.h"
#include "crc32c.h"
#include "utils.h"
#include "volumes.h"
#include "ioctl.h"

#ifdef __CHECKER__
#define BLKGETSIZE64 0
static inline int ioctl(int fd, int define, u64 *size) { return 0; }
#endif

static u64 reference_root_table[6] = {
	[1] =	BTRFS_ROOT_TREE_OBJECTID,
	[2] =	BTRFS_EXTENT_TREE_OBJECTID,
	[3] =	BTRFS_CHUNK_TREE_OBJECTID,
	[4] =	BTRFS_DEV_TREE_OBJECTID,
	[5] =	BTRFS_FS_TREE_OBJECTID,
};

int make_btrfs(int fd, char *device_name,
	       u64 blocks[6], u64 num_bytes, u32 nodesize,
	       u32 leafsize, u32 sectorsize, u32 stripesize)
{
	struct btrfs_super_block super;
	struct extent_buffer *buf;
	struct btrfs_root_item root_item;
	struct btrfs_disk_key disk_key;
	struct btrfs_extent_ref *extent_ref;
	struct btrfs_extent_item *extent_item;
	struct btrfs_inode_item *inode_item;
	struct btrfs_chunk *chunk;
	struct btrfs_dev_item *dev_item;
	struct btrfs_dev_extent *dev_extent;
	u8 *ptr;
	int i;
	int ret;
	u32 itemoff;
	u32 nritems = 0;
	u64 hash;
	u64 first_free;
	u64 ref_gen;
	u64 ref_root;
	u32 array_size;
	u32 item_size;

	first_free = BTRFS_SUPER_INFO_OFFSET + sectorsize * 2 - 1;
	first_free &= ~((u64)sectorsize - 1);

	num_bytes = (num_bytes / sectorsize) * sectorsize;
	uuid_generate(super.fsid);
	btrfs_set_super_bytenr(&super, blocks[0]);
	btrfs_set_super_num_devices(&super, 1);
	strncpy((char *)&super.magic, BTRFS_MAGIC, sizeof(super.magic));
	btrfs_set_super_generation(&super, 1);
	btrfs_set_super_root(&super, blocks[1]);
	btrfs_set_super_chunk_root(&super, blocks[3]);
	btrfs_set_super_total_bytes(&super, num_bytes);
	btrfs_set_super_bytes_used(&super, first_free + 5 * leafsize);
	btrfs_set_super_root_dir(&super, 0);
	btrfs_set_super_sectorsize(&super, sectorsize);
	btrfs_set_super_leafsize(&super, leafsize);
	btrfs_set_super_nodesize(&super, nodesize);
	btrfs_set_super_stripesize(&super, stripesize);
	btrfs_set_super_root_level(&super, 0);
	btrfs_set_super_chunk_root_level(&super, 0);
	btrfs_set_super_sys_array_size(&super, 0);

	buf = malloc(sizeof(*buf) + max(sectorsize, leafsize));

	/* create the tree of root objects */
	memset(buf->data, 0, leafsize);
	btrfs_set_header_bytenr(buf, blocks[1]);
	btrfs_set_header_nritems(buf, 3);
	btrfs_set_header_generation(buf, 1);
	btrfs_set_header_owner(buf, BTRFS_ROOT_TREE_OBJECTID);
	write_extent_buffer(buf, super.fsid, (unsigned long)
			    btrfs_header_fsid(buf), BTRFS_FSID_SIZE);

	/* create the items for the root tree */
	memset(&root_item, 0, sizeof(root_item));
	inode_item = &root_item.inode;
	btrfs_set_stack_inode_generation(inode_item, 1);
	btrfs_set_stack_inode_size(inode_item, 3);
	btrfs_set_stack_inode_nlink(inode_item, 1);
	btrfs_set_stack_inode_nblocks(inode_item, 1);
	btrfs_set_stack_inode_mode(inode_item, S_IFDIR | 0755);
	btrfs_set_root_refs(&root_item, 1);
	btrfs_set_root_used(&root_item, leafsize);

	memset(&disk_key, 0, sizeof(disk_key));
	btrfs_set_disk_key_type(&disk_key, BTRFS_ROOT_ITEM_KEY);
	btrfs_set_disk_key_offset(&disk_key, 0);
	nritems = 0;

	itemoff = __BTRFS_LEAF_DATA_SIZE(leafsize) - sizeof(root_item);
	btrfs_set_root_bytenr(&root_item, blocks[2]);
	btrfs_set_disk_key_objectid(&disk_key, BTRFS_EXTENT_TREE_OBJECTID);
	btrfs_set_item_key(buf, &disk_key, nritems);
	btrfs_set_item_offset(buf, btrfs_item_nr(buf, nritems), itemoff);
	btrfs_set_item_size(buf, btrfs_item_nr(buf, nritems),
			    sizeof(root_item));
	write_extent_buffer(buf, &root_item, btrfs_item_ptr_offset(buf,
			    nritems), sizeof(root_item));
	nritems++;

	itemoff = itemoff - sizeof(root_item);
	btrfs_set_root_bytenr(&root_item, blocks[4]);
	btrfs_set_disk_key_objectid(&disk_key, BTRFS_DEV_TREE_OBJECTID);
	btrfs_set_item_key(buf, &disk_key, nritems);
	btrfs_set_item_offset(buf, btrfs_item_nr(buf, nritems), itemoff);
	btrfs_set_item_size(buf, btrfs_item_nr(buf, nritems),
			    sizeof(root_item));
	write_extent_buffer(buf, &root_item,
			    btrfs_item_ptr_offset(buf, nritems),
			    sizeof(root_item));
	nritems++;

	itemoff = itemoff - sizeof(root_item);
	btrfs_set_root_bytenr(&root_item, blocks[5]);
	btrfs_set_disk_key_objectid(&disk_key, BTRFS_FS_TREE_OBJECTID);
	btrfs_set_item_key(buf, &disk_key, nritems);
	btrfs_set_item_offset(buf, btrfs_item_nr(buf, nritems), itemoff);
	btrfs_set_item_size(buf, btrfs_item_nr(buf, nritems),
			    sizeof(root_item));
	write_extent_buffer(buf, &root_item,
			    btrfs_item_ptr_offset(buf, nritems),
			    sizeof(root_item));
	nritems++;


	ret = pwrite(fd, buf->data, leafsize, blocks[1]);
	BUG_ON(ret != leafsize);

	/* create the items for the extent tree */
	nritems = 0;
	itemoff = __BTRFS_LEAF_DATA_SIZE(leafsize) -
		  sizeof(struct btrfs_extent_item);
	btrfs_set_disk_key_objectid(&disk_key, 0);
	btrfs_set_disk_key_offset(&disk_key, first_free);
	btrfs_set_disk_key_type(&disk_key, BTRFS_EXTENT_ITEM_KEY);
	btrfs_set_item_key(buf, &disk_key, nritems);
	btrfs_set_item_offset(buf, btrfs_item_nr(buf, nritems), itemoff);
	btrfs_set_item_size(buf, btrfs_item_nr(buf,  nritems),
			    sizeof(struct btrfs_extent_item));
	extent_item = btrfs_item_ptr(buf, nritems, struct btrfs_extent_item);
	btrfs_set_extent_refs(buf, extent_item, 1);
	nritems++;
	for (i = 1; i < 6; i++) {
		BUG_ON(blocks[i] < first_free);
		BUG_ON(blocks[i] < blocks[i - 1]);

		/* create extent item */
		itemoff = itemoff - sizeof(struct btrfs_extent_item);
		btrfs_set_disk_key_objectid(&disk_key, blocks[i]);
		btrfs_set_disk_key_offset(&disk_key, leafsize);
		btrfs_set_disk_key_type(&disk_key, BTRFS_EXTENT_ITEM_KEY);
		btrfs_set_item_key(buf, &disk_key, nritems);
		btrfs_set_item_offset(buf, btrfs_item_nr(buf, nritems),
				      itemoff);
		btrfs_set_item_size(buf, btrfs_item_nr(buf, nritems),
				    sizeof(struct btrfs_extent_item));
		extent_item = btrfs_item_ptr(buf, nritems,
					     struct btrfs_extent_item);
		btrfs_set_extent_refs(buf, extent_item, 1);
		nritems++;

		/* create extent ref */
		ref_root = reference_root_table[i];
		if (ref_root == BTRFS_FS_TREE_OBJECTID)
			ref_gen = 1;
		else
			ref_gen = 0;

		hash = btrfs_hash_extent_ref(ref_root, ref_gen, 0, 0);
		itemoff = itemoff - sizeof(struct btrfs_extent_ref);
		btrfs_set_disk_key_objectid(&disk_key, blocks[i]);
		btrfs_set_disk_key_offset(&disk_key, hash);
		btrfs_set_disk_key_type(&disk_key, BTRFS_EXTENT_REF_KEY);
		btrfs_set_item_key(buf, &disk_key, nritems);
		btrfs_set_item_offset(buf, btrfs_item_nr(buf, nritems),
				      itemoff);
		btrfs_set_item_size(buf, btrfs_item_nr(buf, nritems),
				    sizeof(struct btrfs_extent_ref));
		extent_ref = btrfs_item_ptr(buf, nritems,
					     struct btrfs_extent_ref);
		btrfs_set_ref_root(buf, extent_ref, ref_root);
		btrfs_set_ref_generation(buf, extent_ref, ref_gen);
		btrfs_set_ref_objectid(buf, extent_ref, 0);
		btrfs_set_ref_offset(buf, extent_ref, 0);
		nritems++;
	}
	btrfs_set_header_bytenr(buf, blocks[2]);
	btrfs_set_header_owner(buf, BTRFS_EXTENT_TREE_OBJECTID);
	btrfs_set_header_nritems(buf, nritems);
	ret = pwrite(fd, buf->data, leafsize, blocks[2]);
	BUG_ON(ret != leafsize);

	/* create the chunk tree */
	nritems = 0;
	item_size = btrfs_chunk_item_size(1);
	itemoff = __BTRFS_LEAF_DATA_SIZE(leafsize) - item_size;

	/* first we have chunk 0 */
	btrfs_set_disk_key_objectid(&disk_key, 0);
	btrfs_set_disk_key_offset(&disk_key, BTRFS_MKFS_SYSTEM_GROUP_SIZE);
	btrfs_set_disk_key_type(&disk_key, BTRFS_CHUNK_ITEM_KEY);
	btrfs_set_item_key(buf, &disk_key, nritems);
	btrfs_set_item_offset(buf, btrfs_item_nr(buf, nritems), itemoff);
	btrfs_set_item_size(buf, btrfs_item_nr(buf,  nritems), item_size);

	chunk = btrfs_item_ptr(buf, nritems, struct btrfs_chunk);
	btrfs_set_chunk_owner(buf, chunk, BTRFS_EXTENT_TREE_OBJECTID);
	btrfs_set_chunk_stripe_len(buf, chunk, 64 * 1024);
	btrfs_set_chunk_type(buf, chunk, BTRFS_BLOCK_GROUP_SYSTEM);
	btrfs_set_chunk_io_align(buf, chunk, sectorsize);
	btrfs_set_chunk_io_width(buf, chunk, sectorsize);
	btrfs_set_chunk_sector_size(buf, chunk, sectorsize);
	btrfs_set_chunk_num_stripes(buf, chunk, 1);
	btrfs_set_stripe_devid_nr(buf, chunk, 0, 1);
	btrfs_set_stripe_offset_nr(buf, chunk, 0, 0);

	/* copy the key for the chunk to the system array */
	ptr = super.sys_chunk_array;
	array_size = sizeof(disk_key);

	memcpy(ptr, &disk_key, sizeof(disk_key));
	ptr += sizeof(disk_key);

	/* copy the chunk to the system array */
	read_extent_buffer(buf, ptr, (unsigned long)chunk, item_size);
	array_size += item_size;
	ptr += item_size;
	btrfs_set_super_sys_array_size(&super, array_size);

	/* then device 1 (there is no device 0) */
	nritems++;
	item_size = sizeof(*dev_item);
	itemoff = itemoff - item_size;
	btrfs_set_disk_key_objectid(&disk_key, BTRFS_DEV_ITEMS_OBJECTID);
	btrfs_set_disk_key_offset(&disk_key, 1);
	btrfs_set_disk_key_type(&disk_key, BTRFS_DEV_ITEM_KEY);
	btrfs_set_item_key(buf, &disk_key, nritems);
	btrfs_set_item_offset(buf, btrfs_item_nr(buf, nritems), itemoff);
	btrfs_set_item_size(buf, btrfs_item_nr(buf, nritems), item_size);

	dev_item = btrfs_item_ptr(buf, nritems, struct btrfs_dev_item);
	btrfs_set_device_id(buf, dev_item, 1);
	btrfs_set_device_total_bytes(buf, dev_item, num_bytes);
	btrfs_set_device_bytes_used(buf, dev_item,
				    BTRFS_MKFS_SYSTEM_GROUP_SIZE);
	btrfs_set_device_io_align(buf, dev_item, sectorsize);
	btrfs_set_device_io_width(buf, dev_item, sectorsize);
	btrfs_set_device_sector_size(buf, dev_item, sectorsize);
	btrfs_set_device_type(buf, dev_item, 0);
	nritems++;

	uuid_generate(super.dev_item.uuid);

	write_extent_buffer(buf, super.dev_item.uuid,
			    (unsigned long)btrfs_device_uuid(dev_item),
			    BTRFS_DEV_UUID_SIZE);
	read_extent_buffer(buf, &super.dev_item, (unsigned long)dev_item,
			   sizeof(*dev_item));

	btrfs_set_header_bytenr(buf, blocks[3]);
	btrfs_set_header_owner(buf, BTRFS_CHUNK_TREE_OBJECTID);
	btrfs_set_header_nritems(buf, nritems);
	ret = pwrite(fd, buf->data, leafsize, blocks[3]);

	/* create the device tree */
	nritems = 0;
	itemoff = __BTRFS_LEAF_DATA_SIZE(leafsize) -
		sizeof(struct btrfs_dev_extent);

	btrfs_set_disk_key_objectid(&disk_key, 1);
	btrfs_set_disk_key_offset(&disk_key, 0);
	btrfs_set_disk_key_type(&disk_key, BTRFS_DEV_EXTENT_KEY);
	btrfs_set_item_key(buf, &disk_key, nritems);
	btrfs_set_item_offset(buf, btrfs_item_nr(buf, nritems), itemoff);
	btrfs_set_item_size(buf, btrfs_item_nr(buf,  nritems),
			    sizeof(struct btrfs_dev_extent));
	dev_extent = btrfs_item_ptr(buf, nritems, struct btrfs_dev_extent);
	btrfs_set_dev_extent_owner(buf, dev_extent, 0);
	btrfs_set_dev_extent_length(buf, dev_extent,
				    BTRFS_MKFS_SYSTEM_GROUP_SIZE);
	nritems++;

	btrfs_set_header_bytenr(buf, blocks[4]);
	btrfs_set_header_owner(buf, BTRFS_DEV_TREE_OBJECTID);
	btrfs_set_header_nritems(buf, nritems);
	ret = pwrite(fd, buf->data, leafsize, blocks[4]);

	/* finally create the FS root */
	btrfs_set_header_bytenr(buf, blocks[5]);
	btrfs_set_header_owner(buf, BTRFS_FS_TREE_OBJECTID);
	btrfs_set_header_nritems(buf, 0);
	ret = pwrite(fd, buf->data, leafsize, blocks[5]);
	BUG_ON(ret != leafsize);

	/* and write out the super block */
	BUG_ON(sizeof(super) > sectorsize);
	memset(buf->data, 0, sectorsize);
	memcpy(buf->data, &super, sizeof(super));
	ret = pwrite(fd, buf->data, sectorsize, blocks[0]);
	BUG_ON(ret != sectorsize);


	free(buf);
	return 0;
}

static u64 device_size(int fd, struct stat *st)
{
	u64 size;
	if (S_ISREG(st->st_mode)) {
		return st->st_size;
	}
	if (!S_ISBLK(st->st_mode)) {
		return 0;
	}
	if (ioctl(fd, BLKGETSIZE64, &size) >= 0) {
		return size;
	}
	return 0;
}

static int zero_blocks(int fd, off_t start, size_t len)
{
	char *buf = malloc(len);
	int ret = 0;
	ssize_t written;

	if (!buf)
		return -ENOMEM;
	memset(buf, 0, len);
	written = pwrite(fd, buf, len, start);
	if (written != len)
		ret = -EIO;
	free(buf);
	return ret;
}

static int zero_dev_start(int fd)
{
	off_t start = 0;
	size_t len = 2 * 1024 * 1024;

#ifdef __sparc__
	/* don't overwrite the disk labels on sparc */
	start = 1024;
	len -= 1024;
#endif
	return zero_blocks(fd, start, len);
}

static int zero_dev_end(int fd, u64 dev_size)
{
	size_t len = 2 * 1024 * 1024;
	off_t start = dev_size - len;

	return zero_blocks(fd, start, len);
}

int btrfs_add_to_fsid(struct btrfs_trans_handle *trans,
		      struct btrfs_root *root, int fd, u64 block_count,
		      u32 io_width, u32 io_align, u32 sectorsize)
{
	struct btrfs_super_block *disk_super;
	struct btrfs_super_block *super = &root->fs_info->super_copy;
	struct btrfs_device *device;
	struct btrfs_dev_item *dev_item;
	char *buf;
	u64 total_bytes;
	u64 num_devs;
	int ret;

	device = kmalloc(sizeof(*device), GFP_NOFS);
	if (!device)
		return -ENOMEM;
	buf = kmalloc(sectorsize, GFP_NOFS);
	if (!buf) {
		kfree(device);
		return -ENOMEM;
	}
	BUG_ON(sizeof(*disk_super) > sectorsize);
	memset(buf, 0, sectorsize);

	disk_super = (struct btrfs_super_block *)buf;
	dev_item = &disk_super->dev_item;

	uuid_generate(device->uuid);
	device->devid = 0;
	device->type = 0;
	device->io_width = io_width;
	device->io_align = io_align;
	device->sector_size = sectorsize;
	device->fd = 0;
	device->total_bytes = block_count;
	device->bytes_used = 0;
	device->total_ios = 0;
	device->dev_root = root->fs_info->dev_root;

	ret = btrfs_add_device(trans, root, device);
	BUG_ON(ret);

	total_bytes = btrfs_super_total_bytes(super) + block_count;
	btrfs_set_super_total_bytes(super, total_bytes);

	num_devs = btrfs_super_num_devices(super) + 1;
	btrfs_set_super_num_devices(super, num_devs);

	memcpy(disk_super, super, sizeof(*disk_super));

	printf("adding device id %llu\n", (unsigned long long)device->devid);
	btrfs_set_stack_device_id(dev_item, device->devid);
	btrfs_set_stack_device_type(dev_item, device->type);
	btrfs_set_stack_device_io_align(dev_item, device->io_align);
	btrfs_set_stack_device_io_width(dev_item, device->io_width);
	btrfs_set_stack_device_sector_size(dev_item, device->sector_size);
	btrfs_set_stack_device_total_bytes(dev_item, device->total_bytes);
	btrfs_set_stack_device_bytes_used(dev_item, device->bytes_used);
	memcpy(&dev_item->uuid, device->uuid, BTRFS_DEV_UUID_SIZE);

	ret = pwrite(fd, buf, sectorsize, BTRFS_SUPER_INFO_OFFSET);
	BUG_ON(ret != sectorsize);

	kfree(buf);
	list_add(&device->dev_list, &root->fs_info->fs_devices->devices);
	return 0;
}

int btrfs_prepare_device(int fd, char *file, int zero_end, u64 *block_count_ret)
{
	u64 block_count;
	struct stat st;
	int ret;

	ret = fstat(fd, &st);
	if (ret < 0) {
		fprintf(stderr, "unable to stat %s\n", file);
		exit(1);
	}

	block_count = device_size(fd, &st);
	if (block_count == 0) {
		fprintf(stderr, "unable to find %s size\n", file);
		exit(1);
	}
	zero_end = 1;

	if (block_count < 256 * 1024 * 1024) {
		fprintf(stderr, "device %s is too small\n", file);
		exit(1);
	}
	ret = zero_dev_start(fd);
	if (ret) {
		fprintf(stderr, "failed to zero device start %d\n", ret);
		exit(1);
	}

	if (zero_end) {
		ret = zero_dev_end(fd, block_count);
		if (ret) {
			fprintf(stderr, "failed to zero device end %d\n", ret);
			exit(1);
		}
	}
	*block_count_ret = block_count;
	return 0;
}

int btrfs_make_root_dir(struct btrfs_trans_handle *trans,
			struct btrfs_root *root, u64 objectid)
{
	int ret;
	struct btrfs_inode_item inode_item;

	memset(&inode_item, 0, sizeof(inode_item));
	btrfs_set_stack_inode_generation(&inode_item, trans->transid);
	btrfs_set_stack_inode_size(&inode_item, 0);
	btrfs_set_stack_inode_nlink(&inode_item, 1);
	btrfs_set_stack_inode_nblocks(&inode_item, 1);
	btrfs_set_stack_inode_mode(&inode_item, S_IFDIR | 0555);

	if (root->fs_info->tree_root == root)
		btrfs_set_super_root_dir(&root->fs_info->super_copy, objectid);

	ret = btrfs_insert_inode(trans, root, objectid, &inode_item);
	if (ret)
		goto error;

	ret = btrfs_insert_inode_ref(trans, root, "..", 2, objectid, objectid);
	if (ret)
		goto error;

	btrfs_set_root_dirid(&root->root_item, objectid);
	ret = 0;
error:
	return ret;
}

/*
 * returns 1 if the device was mounted, < 0 on error or 0 if everything
 * is safe to continue.  TODO, this should also scan multi-device filesystems
 */
int check_mounted(char *file)
{
	struct mntent *mnt;
	struct stat st_buf;
	dev_t file_dev = 0;
	dev_t file_rdev = 0;
	ino_t file_ino = 0;
	FILE *f;
	int ret = 0;

	if ((f = setmntent ("/proc/mounts", "r")) == NULL)
		return -errno;

	if (stat(file, &st_buf) < 0) {
		return -errno;
	} else {
		if (S_ISBLK(st_buf.st_mode)) {
			file_rdev = st_buf.st_rdev;
		} else {
			file_dev = st_buf.st_dev;
			file_ino = st_buf.st_ino;
		}
	}

	while ((mnt = getmntent (f)) != NULL) {
		if (strcmp(file, mnt->mnt_fsname) == 0)
			break;

		if (stat(mnt->mnt_fsname, &st_buf) == 0) {
			if (S_ISBLK(st_buf.st_mode)) {
				if (file_rdev && (file_rdev == st_buf.st_rdev))
					break;
			} else if (file_dev && ((file_dev == st_buf.st_dev) &&
						(file_ino == st_buf.st_ino))) {
					break;
			}
		}
	}

	if (mnt) {
		/* found an entry in mnt table */
		ret = 1;
	}

	endmntent (f);
	return ret;
}

struct pending_dir {
	struct list_head list;
	char name[256];
};

int btrfs_register_one_device(char *fname)
{
	struct btrfs_ioctl_vol_args args;
	int fd;
	int ret;

	fd = open("/dev/btrfs-control", O_RDONLY);
	if (fd < 0)
		return -EINVAL;
	strcpy(args.name, fname);
	ret = ioctl(fd, BTRFS_IOC_SCAN_DEV, &args);
	close(fd);
	return ret;
}

int btrfs_scan_one_dir(char *dirname, int run_ioctl)
{
	DIR *dirp;
	struct dirent *dirent;
	struct pending_dir *pending;
	struct stat st;
	int ret;
	int fd;
	int dirname_len;
	int pathlen;
	char *fullpath;
	struct list_head pending_list;
	struct btrfs_fs_devices *tmp_devices;
	u64 num_devices;

	INIT_LIST_HEAD(&pending_list);

	pending = malloc(sizeof(*pending));
	if (!pending)
		return -ENOMEM;
	strcpy(pending->name, dirname);

again:
	dirname_len = strlen(pending->name);
	pathlen = 1024;
	fullpath = malloc(pathlen);
	dirname = pending->name;

	if (!fullpath) {
		ret = -ENOMEM;
		goto fail;
	}
	dirp = opendir(dirname);
	if (!dirp) {
		fprintf(stderr, "Unable to open /sys/block for scanning\n");
		return -ENOENT;
	}
	while(1) {
		dirent = readdir(dirp);
		if (!dirent)
			break;
		if (dirent->d_name[0] == '.')
			continue;
		if (dirname_len + strlen(dirent->d_name) + 2 > pathlen) {
			ret = -EFAULT;
			goto fail;
		}
		snprintf(fullpath, pathlen, "%s/%s", dirname, dirent->d_name);
		ret = lstat(fullpath, &st);
		if (ret < 0) {
			fprintf(stderr, "failed to stat %s\n", fullpath);
			continue;
		}
		if (S_ISLNK(st.st_mode))
			continue;
		if (S_ISDIR(st.st_mode)) {
			struct pending_dir *next = malloc(sizeof(*next));
			if (!next) {
				ret = -ENOMEM;
				goto fail;
			}
			strcpy(next->name, fullpath);
			list_add_tail(&next->list, &pending_list);
		}
		if (!S_ISBLK(st.st_mode)) {
			continue;
		}
		fd = open(fullpath, O_RDONLY);
		if (fd < 0) {
			fprintf(stderr, "failed to read %s\n", fullpath);
			continue;
		}
		ret = btrfs_scan_one_device(fd, fullpath, &tmp_devices,
					    &num_devices,
					    BTRFS_SUPER_INFO_OFFSET);
		if (ret == 0 && run_ioctl > 0) {
			btrfs_register_one_device(fullpath);
		}
		close(fd);
	}
	if (!list_empty(&pending_list)) {
		free(pending);
		pending = list_entry(pending_list.next, struct pending_dir,
				     list);
		list_del(&pending->list);
		closedir(dirp);
		goto again;
	}
	ret = 0;
fail:
	free(pending);
	closedir(dirp);
	return ret;
}

int btrfs_scan_for_fsid(struct btrfs_fs_devices *fs_devices, u64 total_devs,
			int run_ioctls)
{
	return btrfs_scan_one_dir("/dev", run_ioctls);
}