btrfs-progs/utils.c

/*
 * Copyright (C) 2007 Oracle.  All rights reserved.
 * Copyright (C) 2008 Morey Roof.  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 700
#define __USE_XOPEN2K8
#define __XOPEN2K8 /* due to an error in dirent.h, to get dirfd() */
#define _GNU_SOURCE	/* O_NOATIME */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <uuid/uuid.h>
#include <fcntl.h>
#include <unistd.h>
#include <mntent.h>
#include <ctype.h>
#include <linux/loop.h>
#include <linux/major.h>
#include <linux/kdev_t.h>
#include <limits.h>
#include <blkid/blkid.h>
#include <sys/vfs.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"

#ifndef BLKDISCARD
#define BLKDISCARD	_IO(0x12,119)
#endif

static int btrfs_scan_done = 0;

static char argv0_buf[ARGV0_BUF_SIZE] = "btrfs";

void fixup_argv0(char **argv, const char *token)
{
	int len = strlen(argv0_buf);

	snprintf(argv0_buf + len, sizeof(argv0_buf) - len, " %s", token);
	argv[0] = argv0_buf;
}

void set_argv0(char **argv)
{
	strncpy(argv0_buf, argv[0], sizeof(argv0_buf));
	argv0_buf[sizeof(argv0_buf) - 1] = 0;
}

int check_argc_exact(int nargs, int expected)
{
	if (nargs < expected)
		fprintf(stderr, "%s: too few arguments\n", argv0_buf);
	if (nargs > expected)
		fprintf(stderr, "%s: too many arguments\n", argv0_buf);

	return nargs != expected;
}

int check_argc_min(int nargs, int expected)
{
	if (nargs < expected) {
		fprintf(stderr, "%s: too few arguments\n", argv0_buf);
		return 1;
	}

	return 0;
}

int check_argc_max(int nargs, int expected)
{
	if (nargs > expected) {
		fprintf(stderr, "%s: too many arguments\n", argv0_buf);
		return 1;
	}

	return 0;
}


/*
 * Discard the given range in one go
 */
static int discard_range(int fd, u64 start, u64 len)
{
	u64 range[2] = { start, len };

	if (ioctl(fd, BLKDISCARD, &range) < 0)
		return errno;
	return 0;
}

/*
 * Discard blocks in the given range in 1G chunks, the process is interruptible
 */
static int discard_blocks(int fd, u64 start, u64 len)
{
	while (len > 0) {
		/* 1G granularity */
		u64 chunk_size = min_t(u64, len, 1*1024*1024*1024);
		int ret;

		ret = discard_range(fd, start, chunk_size);
		if (ret)
			return ret;
		len -= chunk_size;
		start += chunk_size;
	}

	return 0;
}

static u64 reference_root_table[] = {
	[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,
	[6] =	BTRFS_CSUM_TREE_OBJECTID,
};

int test_uuid_unique(char *fs_uuid)
{
	int unique = 1;
	blkid_dev_iterate iter = NULL;
	blkid_dev dev = NULL;
	blkid_cache cache = NULL;

	if (blkid_get_cache(&cache, 0) < 0) {
		printf("ERROR: lblkid cache get failed\n");
		return 1;
	}
	blkid_probe_all(cache);
	iter = blkid_dev_iterate_begin(cache);
	blkid_dev_set_search(iter, "UUID", fs_uuid);

	while (blkid_dev_next(iter, &dev) == 0) {
		dev = blkid_verify(cache, dev);
		if (dev) {
			unique = 0;
			break;
		}
	}

	blkid_dev_iterate_end(iter);
	blkid_put_cache(cache);

	return unique;
}

int make_btrfs(int fd, const char *device, const char *label, char *fs_uuid,
	       u64 blocks[7], u64 num_bytes, u32 nodesize,
	       u32 leafsize, u32 sectorsize, u32 stripesize, u64 features)
{
	struct btrfs_super_block super;
	struct extent_buffer *buf = NULL;
	struct btrfs_root_item root_item;
	struct btrfs_disk_key disk_key;
	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 chunk_tree_uuid[BTRFS_UUID_SIZE];
	u8 *ptr;
	int i;
	int ret;
	u32 itemoff;
	u32 nritems = 0;
	u64 first_free;
	u64 ref_root;
	u32 array_size;
	u32 item_size;
	int skinny_metadata = !!(features &
				 BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA);

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

	memset(&super, 0, sizeof(super));

	num_bytes = (num_bytes / sectorsize) * sectorsize;
	if (fs_uuid) {
		if (uuid_parse(fs_uuid, super.fsid) != 0) {
			fprintf(stderr, "could not parse UUID: %s\n", fs_uuid);
			ret = -EINVAL;
			goto out;
		}
		if (!test_uuid_unique(fs_uuid)) {
			fprintf(stderr, "non-unique UUID: %s\n", fs_uuid);
			ret = -EBUSY;
			goto out;
		}
	} else {
		uuid_generate(super.fsid);
	}
	uuid_generate(super.dev_item.uuid);
	uuid_generate(chunk_tree_uuid);

	btrfs_set_super_bytenr(&super, blocks[0]);
	btrfs_set_super_num_devices(&super, 1);
	btrfs_set_super_magic(&super, BTRFS_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, 6 * leafsize);
	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_csum_type(&super, BTRFS_CSUM_TYPE_CRC32);
	btrfs_set_super_chunk_root_generation(&super, 1);
	btrfs_set_super_cache_generation(&super, -1);
	btrfs_set_super_incompat_flags(&super, features);
	if (label)
		strncpy(super.label, label, BTRFS_LABEL_SIZE - 1);

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

	/* create the tree of root objects */
	memset(buf->data, 0, leafsize);
	buf->len = leafsize;
	btrfs_set_header_bytenr(buf, blocks[1]);
	btrfs_set_header_nritems(buf, 4);
	btrfs_set_header_generation(buf, 1);
	btrfs_set_header_backref_rev(buf, BTRFS_MIXED_BACKREF_REV);
	btrfs_set_header_owner(buf, BTRFS_ROOT_TREE_OBJECTID);
	write_extent_buffer(buf, super.fsid, btrfs_header_fsid(),
			    BTRFS_FSID_SIZE);

	write_extent_buffer(buf, chunk_tree_uuid,
			    btrfs_header_chunk_tree_uuid(buf),
			    BTRFS_UUID_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_nbytes(inode_item, leafsize);
	btrfs_set_stack_inode_mode(inode_item, S_IFDIR | 0755);
	btrfs_set_root_refs(&root_item, 1);
	btrfs_set_root_used(&root_item, leafsize);
	btrfs_set_root_generation(&root_item, 1);

	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(nritems), itemoff);
	btrfs_set_item_size(buf, btrfs_item_nr(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(nritems), itemoff);
	btrfs_set_item_size(buf, btrfs_item_nr(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(nritems), itemoff);
	btrfs_set_item_size(buf, btrfs_item_nr(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[6]);
	btrfs_set_disk_key_objectid(&disk_key, BTRFS_CSUM_TREE_OBJECTID);
	btrfs_set_item_key(buf, &disk_key, nritems);
	btrfs_set_item_offset(buf, btrfs_item_nr(nritems), itemoff);
	btrfs_set_item_size(buf, btrfs_item_nr(nritems),
			    sizeof(root_item));
	write_extent_buffer(buf, &root_item,
			    btrfs_item_ptr_offset(buf, nritems),
			    sizeof(root_item));
	nritems++;


	csum_tree_block_size(buf, BTRFS_CRC32_SIZE, 0);
	ret = pwrite(fd, buf->data, leafsize, blocks[1]);
	if (ret != leafsize) {
		ret = (ret < 0 ? -errno : -EIO);
		goto out;
	}

	/* create the items for the extent tree */
	memset(buf->data+sizeof(struct btrfs_header), 0,
		leafsize-sizeof(struct btrfs_header));
	nritems = 0;
	itemoff = __BTRFS_LEAF_DATA_SIZE(leafsize);
	for (i = 1; i < 7; i++) {
		item_size = sizeof(struct btrfs_extent_item);
		if (!skinny_metadata)
			item_size += sizeof(struct btrfs_tree_block_info);

		BUG_ON(blocks[i] < first_free);
		BUG_ON(blocks[i] < blocks[i - 1]);

		/* create extent item */
		itemoff -= item_size;
		btrfs_set_disk_key_objectid(&disk_key, blocks[i]);
		if (skinny_metadata) {
			btrfs_set_disk_key_type(&disk_key,
						BTRFS_METADATA_ITEM_KEY);
			btrfs_set_disk_key_offset(&disk_key, 0);
		} else {
			btrfs_set_disk_key_type(&disk_key,
						BTRFS_EXTENT_ITEM_KEY);
			btrfs_set_disk_key_offset(&disk_key, leafsize);
		}
		btrfs_set_item_key(buf, &disk_key, nritems);
		btrfs_set_item_offset(buf, btrfs_item_nr(nritems),
				      itemoff);
		btrfs_set_item_size(buf, btrfs_item_nr(nritems),
				    item_size);
		extent_item = btrfs_item_ptr(buf, nritems,
					     struct btrfs_extent_item);
		btrfs_set_extent_refs(buf, extent_item, 1);
		btrfs_set_extent_generation(buf, extent_item, 1);
		btrfs_set_extent_flags(buf, extent_item,
				       BTRFS_EXTENT_FLAG_TREE_BLOCK);
		nritems++;

		/* create extent ref */
		ref_root = reference_root_table[i];
		btrfs_set_disk_key_objectid(&disk_key, blocks[i]);
		btrfs_set_disk_key_offset(&disk_key, ref_root);
		btrfs_set_disk_key_type(&disk_key, BTRFS_TREE_BLOCK_REF_KEY);
		btrfs_set_item_key(buf, &disk_key, nritems);
		btrfs_set_item_offset(buf, btrfs_item_nr(nritems),
				      itemoff);
		btrfs_set_item_size(buf, btrfs_item_nr(nritems), 0);
		nritems++;
	}
	btrfs_set_header_bytenr(buf, blocks[2]);
	btrfs_set_header_owner(buf, BTRFS_EXTENT_TREE_OBJECTID);
	btrfs_set_header_nritems(buf, nritems);
	csum_tree_block_size(buf, BTRFS_CRC32_SIZE, 0);
	ret = pwrite(fd, buf->data, leafsize, blocks[2]);
	if (ret != leafsize) {
		ret = (ret < 0 ? -errno : -EIO);
		goto out;
	}

	/* create the chunk tree */
	memset(buf->data+sizeof(struct btrfs_header), 0,
		leafsize-sizeof(struct btrfs_header));
	nritems = 0;
	item_size = sizeof(*dev_item);
	itemoff = __BTRFS_LEAF_DATA_SIZE(leafsize) - item_size;

	/* first device 1 (there is no device 0) */
	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(nritems), itemoff);
	btrfs_set_item_size(buf, btrfs_item_nr(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_generation(buf, dev_item, 0);
	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);

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

	nritems++;
	item_size = btrfs_chunk_item_size(1);
	itemoff = itemoff - item_size;

	/* then we have chunk 0 */
	btrfs_set_disk_key_objectid(&disk_key, BTRFS_FIRST_CHUNK_TREE_OBJECTID);
	btrfs_set_disk_key_offset(&disk_key, 0);
	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(nritems), itemoff);
	btrfs_set_item_size(buf, btrfs_item_nr(nritems), item_size);

	chunk = btrfs_item_ptr(buf, nritems, struct btrfs_chunk);
	btrfs_set_chunk_length(buf, chunk, BTRFS_MKFS_SYSTEM_GROUP_SIZE);
	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);
	nritems++;

	write_extent_buffer(buf, super.dev_item.uuid,
			    (unsigned long)btrfs_stripe_dev_uuid(&chunk->stripe),
			    BTRFS_UUID_SIZE);

	/* 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);

	btrfs_set_header_bytenr(buf, blocks[3]);
	btrfs_set_header_owner(buf, BTRFS_CHUNK_TREE_OBJECTID);
	btrfs_set_header_nritems(buf, nritems);
	csum_tree_block_size(buf, BTRFS_CRC32_SIZE, 0);
	ret = pwrite(fd, buf->data, leafsize, blocks[3]);
	if (ret != leafsize) {
		ret = (ret < 0 ? -errno : -EIO);
		goto out;
	}

	/* create the device tree */
	memset(buf->data+sizeof(struct btrfs_header), 0,
		leafsize-sizeof(struct btrfs_header));
	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(nritems), itemoff);
	btrfs_set_item_size(buf, btrfs_item_nr(nritems),
			    sizeof(struct btrfs_dev_extent));
	dev_extent = btrfs_item_ptr(buf, nritems, struct btrfs_dev_extent);
	btrfs_set_dev_extent_chunk_tree(buf, dev_extent,
					BTRFS_CHUNK_TREE_OBJECTID);
	btrfs_set_dev_extent_chunk_objectid(buf, dev_extent,
					BTRFS_FIRST_CHUNK_TREE_OBJECTID);
	btrfs_set_dev_extent_chunk_offset(buf, dev_extent, 0);

	write_extent_buffer(buf, chunk_tree_uuid,
		    (unsigned long)btrfs_dev_extent_chunk_tree_uuid(dev_extent),
		    BTRFS_UUID_SIZE);

	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);
	csum_tree_block_size(buf, BTRFS_CRC32_SIZE, 0);
	ret = pwrite(fd, buf->data, leafsize, blocks[4]);
	if (ret != leafsize) {
		ret = (ret < 0 ? -errno : -EIO);
		goto out;
	}

	/* create the FS root */
	memset(buf->data+sizeof(struct btrfs_header), 0,
		leafsize-sizeof(struct btrfs_header));
	btrfs_set_header_bytenr(buf, blocks[5]);
	btrfs_set_header_owner(buf, BTRFS_FS_TREE_OBJECTID);
	btrfs_set_header_nritems(buf, 0);
	csum_tree_block_size(buf, BTRFS_CRC32_SIZE, 0);
	ret = pwrite(fd, buf->data, leafsize, blocks[5]);
	if (ret != leafsize) {
		ret = (ret < 0 ? -errno : -EIO);
		goto out;
	}
	/* finally create the csum root */
	memset(buf->data+sizeof(struct btrfs_header), 0,
		leafsize-sizeof(struct btrfs_header));
	btrfs_set_header_bytenr(buf, blocks[6]);
	btrfs_set_header_owner(buf, BTRFS_CSUM_TREE_OBJECTID);
	btrfs_set_header_nritems(buf, 0);
	csum_tree_block_size(buf, BTRFS_CRC32_SIZE, 0);
	ret = pwrite(fd, buf->data, leafsize, blocks[6]);
	if (ret != leafsize) {
		ret = (ret < 0 ? -errno : -EIO);
		goto out;
	}

	/* and write out the super block */
	BUG_ON(sizeof(super) > sectorsize);
	memset(buf->data, 0, sectorsize);
	memcpy(buf->data, &super, sizeof(super));
	buf->len = sectorsize;
	csum_tree_block_size(buf, BTRFS_CRC32_SIZE, 0);
	ret = pwrite(fd, buf->data, sectorsize, blocks[0]);
	if (ret != sectorsize) {
		ret = (ret < 0 ? -errno : -EIO);
		goto out;
	}

	ret = 0;

out:
	free(buf);
	return ret;
}

u64 btrfs_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;
}

#define ZERO_DEV_BYTES (2 * 1024 * 1024)

/* don't write outside the device by clamping the region to the device size */
static int zero_dev_clamped(int fd, off_t start, ssize_t len, u64 dev_size)
{
	off_t end = max(start, start + len);

#ifdef __sparc__
	/* and don't overwrite the disk labels on sparc */
	start = max(start, 1024);
	end = max(end, 1024);
#endif

	start = min_t(u64, start, dev_size);
	end = min_t(u64, end, dev_size);

	return zero_blocks(fd, start, end - start);
}

int btrfs_add_to_fsid(struct btrfs_trans_handle *trans,
		      struct btrfs_root *root, int fd, char *path,
		      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 = kzalloc(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 = fd;
	device->writeable = 1;
	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 %s id %llu\n", path,
	       (unsigned long long)device->devid);

	btrfs_set_super_bytenr(disk_super, BTRFS_SUPER_INFO_OFFSET);
	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_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);
	device->fs_devices = root->fs_info->fs_devices;
	return 0;
}

static void btrfs_wipe_existing_sb(int fd)
{
	const char *off = NULL;
	size_t len = 0;
	loff_t offset;
	char buf[BUFSIZ];
	int rc = 0;
	blkid_probe pr = NULL;

	pr = blkid_new_probe();
	if (!pr)
		return;

	if (blkid_probe_set_device(pr, fd, 0, 0))
		goto out;

	rc = blkid_probe_lookup_value(pr, "SBMAGIC_OFFSET", &off, NULL);
	if (!rc)
		rc = blkid_probe_lookup_value(pr, "SBMAGIC", NULL, &len);

	if (rc || len == 0 || off == NULL)
		goto out;

	offset = strtoll(off, NULL, 10);
	if (len > sizeof(buf))
		len = sizeof(buf);

	memset(buf, 0, len);
	rc = pwrite(fd, buf, len, offset);
	fsync(fd);

out:
	blkid_free_probe(pr);
	return;
}

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

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

	block_count = btrfs_device_size(fd, &st);
	if (block_count == 0) {
		fprintf(stderr, "unable to find %s size\n", file);
		return 1;
	}
	if (max_block_count)
		block_count = min(block_count, max_block_count);

	if (block_count < BTRFS_MKFS_SMALL_VOLUME_SIZE && !(*mixed))
		*mixed = 1;

	if (discard) {
		/*
		 * We intentionally ignore errors from the discard ioctl.  It
		 * is not necessary for the mkfs functionality but just an
		 * optimization.
		 */
		if (discard_range(fd, 0, 0) == 0) {
			fprintf(stderr, "Performing full device TRIM (%s) ...\n",
				pretty_size(block_count));
			discard_blocks(fd, 0, block_count);
		}
	}

	ret = zero_dev_clamped(fd, 0, ZERO_DEV_BYTES, block_count);
	for (i = 0 ; !ret && i < BTRFS_SUPER_MIRROR_MAX; i++)
		ret = zero_dev_clamped(fd, btrfs_sb_offset(i),
				       BTRFS_SUPER_INFO_SIZE, block_count);
	if (!ret && zero_end)
		ret = zero_dev_clamped(fd, block_count - ZERO_DEV_BYTES,
				       ZERO_DEV_BYTES, block_count);

	if (ret < 0) {
		fprintf(stderr, "ERROR: failed to zero device '%s' - %s\n",
			file, strerror(-ret));
		return 1;
	}

	btrfs_wipe_existing_sb(fd);

	*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;
	time_t now = time(NULL);

	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_nbytes(&inode_item, root->leafsize);
	btrfs_set_stack_inode_mode(&inode_item, S_IFDIR | 0755);
	btrfs_set_stack_timespec_sec(&inode_item.atime, now);
	btrfs_set_stack_timespec_nsec(&inode_item.atime, 0);
	btrfs_set_stack_timespec_sec(&inode_item.ctime, now);
	btrfs_set_stack_timespec_nsec(&inode_item.ctime, 0);
	btrfs_set_stack_timespec_sec(&inode_item.mtime, now);
	btrfs_set_stack_timespec_nsec(&inode_item.mtime, 0);
	btrfs_set_stack_timespec_sec(&inode_item.otime, 0);
	btrfs_set_stack_timespec_nsec(&inode_item.otime, 0);

	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, 0);
	if (ret)
		goto error;

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

/*
 * checks if a path is a block device node
 * Returns negative errno on failure, otherwise
 * returns 1 for blockdev, 0 for not-blockdev
 */
int is_block_device(const char *path)
{
	struct stat statbuf;

	if (stat(path, &statbuf) < 0)
		return -errno;

	return S_ISBLK(statbuf.st_mode);
}

/*
 * check if given path is a mount point
 * return 1 if yes. 0 if no. -1 for error
 */
int is_mount_point(const char *path)
{
	FILE *f;
	struct mntent *mnt;
	int ret = 0;

	f = setmntent("/proc/self/mounts", "r");
	if (f == NULL)
		return -1;

	while ((mnt = getmntent(f)) != NULL) {
		if (strcmp(mnt->mnt_dir, path))
			continue;
		ret = 1;
		break;
	}
	endmntent(f);
	return ret;
}

/*
 * Find the mount point for a mounted device.
 * On success, returns 0 with mountpoint in *mp.
 * On failure, returns -errno (not mounted yields -EINVAL)
 * Is noisy on failures, expects to be given a mounted device.
 */
int get_btrfs_mount(const char *dev, char *mp, size_t mp_size)
{
	int ret;
	int fd = -1;

	ret = is_block_device(dev);
	if (ret <= 0) {
		if (!ret) {
			fprintf(stderr, "%s is not a block device\n", dev);
			ret = -EINVAL;
		} else {
			fprintf(stderr, "Could not check %s: %s\n",
				dev, strerror(-ret));
		}
		goto out;
	}

	fd = open(dev, O_RDONLY);
	if (fd < 0) {
		ret = -errno;
		fprintf(stderr, "Could not open %s: %s\n", dev, strerror(errno));
		goto out;
	}

	ret = check_mounted_where(fd, dev, mp, mp_size, NULL);
	if (!ret) {
		ret = -EINVAL;
	} else { /* mounted, all good */
		ret = 0;
	}
out:
	if (fd != -1)
		close(fd);
	return ret;
}

/*
 * Given a pathname, return a filehandle to:
 * 	the original pathname or,
 * 	if the pathname is a mounted btrfs device, to its mountpoint.
 *
 * On error, return -1, errno should be set.
 */
int open_path_or_dev_mnt(const char *path, DIR **dirstream)
{
	char mp[BTRFS_PATH_NAME_MAX + 1];
	int fdmnt;

	if (is_block_device(path)) {
		int ret;

		ret = get_btrfs_mount(path, mp, sizeof(mp));
		if (ret < 0) {
			/* not a mounted btrfs dev */
			errno = EINVAL;
			return -1;
		}
		fdmnt = open_file_or_dir(mp, dirstream);
	} else {
		fdmnt = open_file_or_dir(path, dirstream);
	}

	return fdmnt;
}

/* checks if a device is a loop device */
static int is_loop_device (const char* device) {
	struct stat statbuf;

	if(stat(device, &statbuf) < 0)
		return -errno;

	return (S_ISBLK(statbuf.st_mode) &&
		MAJOR(statbuf.st_rdev) == LOOP_MAJOR);
}


/* Takes a loop device path (e.g. /dev/loop0) and returns
 * the associated file (e.g. /images/my_btrfs.img) */
static int resolve_loop_device(const char* loop_dev, char* loop_file,
		int max_len)
{
	int ret;
	FILE *f;
	char fmt[20];
	char p[PATH_MAX];
	char real_loop_dev[PATH_MAX];

	if (!realpath(loop_dev, real_loop_dev))
		return -errno;
	snprintf(p, PATH_MAX, "/sys/block/%s/loop/backing_file", strrchr(real_loop_dev, '/'));
	if (!(f = fopen(p, "r")))
		return -errno;

	snprintf(fmt, 20, "%%%i[^\n]", max_len-1);
	ret = fscanf(f, fmt, loop_file);
	fclose(f);
	if (ret == EOF)
		return -errno;

	return 0;
}

/* Checks whether a and b are identical or device
 * files associated with the same block device
 */
static int is_same_blk_file(const char* a, const char* b)
{
	struct stat st_buf_a, st_buf_b;
	char real_a[PATH_MAX];
	char real_b[PATH_MAX];

	if(!realpath(a, real_a))
		strcpy(real_a, a);

	if (!realpath(b, real_b))
		strcpy(real_b, b);

	/* Identical path? */
	if(strcmp(real_a, real_b) == 0)
		return 1;

	if(stat(a, &st_buf_a) < 0 ||
	   stat(b, &st_buf_b) < 0)
	{
		if (errno == ENOENT)
			return 0;
		return -errno;
	}

	/* Same blockdevice? */
	if(S_ISBLK(st_buf_a.st_mode) &&
	   S_ISBLK(st_buf_b.st_mode) &&
	   st_buf_a.st_rdev == st_buf_b.st_rdev)
	{
		return 1;
	}

	/* Hardlink? */
	if (st_buf_a.st_dev == st_buf_b.st_dev &&
	    st_buf_a.st_ino == st_buf_b.st_ino)
	{
		return 1;
	}

	return 0;
}

/* checks if a and b are identical or device
 * files associated with the same block device or
 * if one file is a loop device that uses the other
 * file.
 */
static int is_same_loop_file(const char* a, const char* b)
{
	char res_a[PATH_MAX];
	char res_b[PATH_MAX];
	const char* final_a = NULL;
	const char* final_b = NULL;
	int ret;

	/* Resolve a if it is a loop device */
	if((ret = is_loop_device(a)) < 0) {
		if (ret == -ENOENT)
			return 0;
		return ret;
	} else if (ret) {
		ret = resolve_loop_device(a, res_a, sizeof(res_a));
		if (ret < 0) {
			if (errno != EPERM)
				return ret;
		} else {
			final_a = res_a;
		}
	} else {
		final_a = a;
	}

	/* Resolve b if it is a loop device */
	if ((ret = is_loop_device(b)) < 0) {
		if (ret == -ENOENT)
			return 0;
		return ret;
	} else if (ret) {
		ret = resolve_loop_device(b, res_b, sizeof(res_b));
		if (ret < 0) {
			if (errno != EPERM)
				return ret;
		} else {
			final_b = res_b;
		}
	} else {
		final_b = b;
	}

	return is_same_blk_file(final_a, final_b);
}

/* Checks if a file exists and is a block or regular file*/
static int is_existing_blk_or_reg_file(const char* filename)
{
	struct stat st_buf;

	if(stat(filename, &st_buf) < 0) {
		if(errno == ENOENT)
			return 0;
		else
			return -errno;
	}

	return (S_ISBLK(st_buf.st_mode) || S_ISREG(st_buf.st_mode));
}

/* Checks if a file is used (directly or indirectly via a loop device)
 * by a device in fs_devices
 */
static int blk_file_in_dev_list(struct btrfs_fs_devices* fs_devices,
		const char* file)
{
	int ret;
	struct list_head *head;
	struct list_head *cur;
	struct btrfs_device *device;

	head = &fs_devices->devices;
	list_for_each(cur, head) {
		device = list_entry(cur, struct btrfs_device, dev_list);

		if((ret = is_same_loop_file(device->name, file)))
			return ret;
	}

	return 0;
}

/*
 * Resolve a pathname to a device mapper node to /dev/mapper/<name>
 * Returns NULL on invalid input or malloc failure; Other failures
 * will be handled by the caller using the input pathame.
 */
char *canonicalize_dm_name(const char *ptname)
{
	FILE	*f;
	size_t	sz;
	char	path[PATH_MAX], name[PATH_MAX], *res = NULL;

	if (!ptname || !*ptname)
		return NULL;

	snprintf(path, sizeof(path), "/sys/block/%s/dm/name", ptname);
	if (!(f = fopen(path, "r")))
		return NULL;

	/* read <name>\n from sysfs */
	if (fgets(name, sizeof(name), f) && (sz = strlen(name)) > 1) {
		name[sz - 1] = '\0';
		snprintf(path, sizeof(path), "/dev/mapper/%s", name);

		if (access(path, F_OK) == 0)
			res = strdup(path);
	}
	fclose(f);
	return res;
}

/*
 * Resolve a pathname to a canonical device node, e.g. /dev/sda1 or
 * to a device mapper pathname.
 * Returns NULL on invalid input or malloc failure; Other failures
 * will be handled by the caller using the input pathame.
 */
char *canonicalize_path(const char *path)
{
	char *canonical, *p;

	if (!path || !*path)
		return NULL;

	canonical = realpath(path, NULL);
	if (!canonical)
		return strdup(path);
	p = strrchr(canonical, '/');
	if (p && strncmp(p, "/dm-", 4) == 0 && isdigit(*(p + 4))) {
		char *dm = canonicalize_dm_name(p + 1);

		if (dm) {
			free(canonical);
			return dm;
		}
	}
	return canonical;
}

/*
 * returns 1 if the device was mounted, < 0 on error or 0 if everything
 * is safe to continue.
 */
int check_mounted(const char* file)
{
	int fd;
	int ret;

	fd = open(file, O_RDONLY);
	if (fd < 0) {
		fprintf (stderr, "check_mounted(): Could not open %s\n", file);
		return -errno;
	}

	ret =  check_mounted_where(fd, file, NULL, 0, NULL);
	close(fd);

	return ret;
}

int check_mounted_where(int fd, const char *file, char *where, int size,
			struct btrfs_fs_devices **fs_dev_ret)
{
	int ret;
	u64 total_devs = 1;
	int is_btrfs;
	struct btrfs_fs_devices *fs_devices_mnt = NULL;
	FILE *f;
	struct mntent *mnt;

	/* scan the initial device */
	ret = btrfs_scan_one_device(fd, file, &fs_devices_mnt,
				    &total_devs, BTRFS_SUPER_INFO_OFFSET, 0);
	is_btrfs = (ret >= 0);

	/* scan other devices */
	if (is_btrfs && total_devs > 1) {
		ret = btrfs_scan_lblkid();
		if (ret)
			return ret;
	}

	/* iterate over the list of currently mountes filesystems */
	if ((f = setmntent ("/proc/self/mounts", "r")) == NULL)
		return -errno;

	while ((mnt = getmntent (f)) != NULL) {
		if(is_btrfs) {
			if(strcmp(mnt->mnt_type, "btrfs") != 0)
				continue;

			ret = blk_file_in_dev_list(fs_devices_mnt, mnt->mnt_fsname);
		} else {
			/* ignore entries in the mount table that are not
			   associated with a file*/
			if((ret = is_existing_blk_or_reg_file(mnt->mnt_fsname)) < 0)
				goto out_mntloop_err;
			else if(!ret)
				continue;

			ret = is_same_loop_file(file, mnt->mnt_fsname);
		}

		if(ret < 0)
			goto out_mntloop_err;
		else if(ret)
			break;
	}

	/* Did we find an entry in mnt table? */
	if (mnt && size && where) {
		strncpy(where, mnt->mnt_dir, size);
		where[size-1] = 0;
	}
	if (fs_dev_ret)
		*fs_dev_ret = fs_devices_mnt;

	ret = (mnt != NULL);

out_mntloop_err:
	endmntent (f);

	return ret;
}

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

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

	fd = open("/dev/btrfs-control", O_RDWR);
	if (fd < 0) {
		fprintf(stderr, "failed to open /dev/btrfs-control "
			"skipping device registration: %s\n",
			strerror(errno));
		return -errno;
	}
	strncpy(args.name, fname, BTRFS_PATH_NAME_MAX);
	args.name[BTRFS_PATH_NAME_MAX-1] = 0;
	ret = ioctl(fd, BTRFS_IOC_SCAN_DEV, &args);
	e = errno;
	if (ret < 0) {
		fprintf(stderr, "ERROR: device scan failed '%s' - %s\n",
			fname, strerror(e));
		ret = -e;
	}
	close(fd);
	return ret;
}

/*
 * Register all devices in the fs_uuid list created in the user
 * space. Ensure btrfs_scan_lblkid() is called before this func.
 */
int btrfs_register_all_devices(void)
{
	int err;
	struct btrfs_fs_devices *fs_devices;
	struct btrfs_device *device;
	struct list_head *all_uuids;

	all_uuids = btrfs_scanned_uuids();

	list_for_each_entry(fs_devices, all_uuids, list) {
		list_for_each_entry(device, &fs_devices->devices, dev_list) {
			if (strlen(device->name) != 0) {
				err = btrfs_register_one_device(device->name);
				if (err < 0)
					return err;
				if (err > 0)
					return -err;
			}
		}
	}
	return 0;
}

int btrfs_device_already_in_root(struct btrfs_root *root, int fd,
				 int super_offset)
{
	struct btrfs_super_block *disk_super;
	char *buf;
	int ret = 0;

	buf = malloc(BTRFS_SUPER_INFO_SIZE);
	if (!buf) {
		ret = -ENOMEM;
		goto out;
	}
	ret = pread(fd, buf, BTRFS_SUPER_INFO_SIZE, super_offset);
	if (ret != BTRFS_SUPER_INFO_SIZE)
		goto brelse;

	ret = 0;
	disk_super = (struct btrfs_super_block *)buf;
	if (btrfs_super_magic(disk_super) != BTRFS_MAGIC)
		goto brelse;

	if (!memcmp(disk_super->fsid, root->fs_info->super_copy->fsid,
		    BTRFS_FSID_SIZE))
		ret = 1;
brelse:
	free(buf);
out:
	return ret;
}

static const char* unit_suffix_binary[] =
	{ "B", "KiB", "MiB", "GiB", "TiB", "PiB", "EiB"};
static const char* unit_suffix_decimal[] =
	{ "B", "kB", "MB", "GB", "TB", "PB", "EB"};

int pretty_size_snprintf(u64 size, char *str, size_t str_size, unsigned unit_mode)
{
	int num_divs;
	float fraction;
	u64 base = 0;
	int mult = 0;
	const char** suffix = NULL;
	u64 last_size;

	if (str_size == 0)
		return 0;

	if ((unit_mode & ~UNITS_MODE_MASK) == UNITS_RAW) {
		snprintf(str, str_size, "%llu", size);
		return 0;
	}

	if ((unit_mode & ~UNITS_MODE_MASK) == UNITS_BINARY) {
		base = 1024;
		mult = 1024;
		suffix = unit_suffix_binary;
	} else if ((unit_mode & ~UNITS_MODE_MASK) == UNITS_DECIMAL) {
		base = 1000;
		mult = 1000;
		suffix = unit_suffix_decimal;
	}

	/* Unknown mode */
	if (!base) {
		fprintf(stderr, "INTERNAL ERROR: unknown unit base, mode %d\n",
				unit_mode);
		assert(0);
		return -1;
	}

	num_divs = 0;
	last_size = size;
	switch (unit_mode & UNITS_MODE_MASK) {
	case UNITS_TBYTES: base *= mult; num_divs++;
	case UNITS_GBYTES: base *= mult; num_divs++;
	case UNITS_MBYTES: base *= mult; num_divs++;
	case UNITS_KBYTES: num_divs++;
			   break;
	case UNITS_BYTES:
			   base = 1;
			   num_divs = 0;
			   break;
	default:
		while (size >= mult) {
			last_size = size;
			size /= mult;
			num_divs++;
		}
	}

	if (num_divs >= ARRAY_SIZE(unit_suffix_binary)) {
		str[0] = '\0';
		printf("INTERNAL ERROR: unsupported unit suffix, index %d\n",
				num_divs);
		assert(0);
		return -1;
	}
	fraction = (float)last_size / base;

	return snprintf(str, str_size, "%.2f%s", fraction, suffix[num_divs]);
}

/*
 * __strncpy__null - strncpy with null termination
 * @dest:	the target array
 * @src:	the source string
 * @n:		maximum bytes to copy (size of *dest)
 *
 * Like strncpy, but ensures destination is null-terminated.
 *
 * Copies the string pointed to by src, including the terminating null
 * byte ('\0'), to the buffer pointed to by dest, up to a maximum
 * of n bytes.  Then ensure that dest is null-terminated.
 */
char *__strncpy__null(char *dest, const char *src, size_t n)
{
	strncpy(dest, src, n);
	if (n > 0)
		dest[n - 1] = '\0';
	return dest;
}

/*
 * Checks to make sure that the label matches our requirements.
 * Returns:
       0    if everything is safe and usable
      -1    if the label is too long
 */
static int check_label(const char *input)
{
       int len = strlen(input);

       if (len > BTRFS_LABEL_SIZE - 1) {
		fprintf(stderr, "ERROR: Label %s is too long (max %d)\n",
			input, BTRFS_LABEL_SIZE - 1);
               return -1;
       }

       return 0;
}

static int set_label_unmounted(const char *dev, const char *label)
{
	struct btrfs_trans_handle *trans;
	struct btrfs_root *root;
	int ret;

	ret = check_mounted(dev);
	if (ret < 0) {
	       fprintf(stderr, "FATAL: error checking %s mount status\n", dev);
	       return -1;
	}
	if (ret > 0) {
		fprintf(stderr, "ERROR: dev %s is mounted, use mount point\n",
			dev);
		return -1;
	}

	/* Open the super_block at the default location
	 * and as read-write.
	 */
	root = open_ctree(dev, 0, OPEN_CTREE_WRITES);
	if (!root) /* errors are printed by open_ctree() */
		return -1;

	trans = btrfs_start_transaction(root, 1);
	snprintf(root->fs_info->super_copy->label, BTRFS_LABEL_SIZE, "%s",
		 label);
	btrfs_commit_transaction(trans, root);

	/* Now we close it since we are done. */
	close_ctree(root);
	return 0;
}

static int set_label_mounted(const char *mount_path, const char *label)
{
	int fd;

	fd = open(mount_path, O_RDONLY | O_NOATIME);
	if (fd < 0) {
		fprintf(stderr, "ERROR: unable to access '%s'\n", mount_path);
		return -1;
	}

	if (ioctl(fd, BTRFS_IOC_SET_FSLABEL, label) < 0) {
		fprintf(stderr, "ERROR: unable to set label %s\n",
			strerror(errno));
		close(fd);
		return -1;
	}

	close(fd);
	return 0;
}

static int get_label_unmounted(const char *dev, char *label)
{
	struct btrfs_root *root;
	int ret;

	ret = check_mounted(dev);
	if (ret < 0) {
	       fprintf(stderr, "FATAL: error checking %s mount status\n", dev);
	       return -1;
	}
	if (ret > 0) {
		fprintf(stderr, "ERROR: dev %s is mounted, use mount point\n",
			dev);
		return -1;
	}

	/* Open the super_block at the default location
	 * and as read-only.
	 */
	root = open_ctree(dev, 0, 0);
	if(!root)
		return -1;

	memcpy(label, root->fs_info->super_copy->label, BTRFS_LABEL_SIZE);

	/* Now we close it since we are done. */
	close_ctree(root);
	return 0;
}

/*
 * If a partition is mounted, try to get the filesystem label via its
 * mounted path rather than device.  Return the corresponding error
 * the user specified the device path.
 */
int get_label_mounted(const char *mount_path, char *labelp)
{
	char label[BTRFS_LABEL_SIZE];
	int fd;

	fd = open(mount_path, O_RDONLY | O_NOATIME);
	if (fd < 0) {
		fprintf(stderr, "ERROR: unable to access '%s'\n", mount_path);
		return -1;
	}

	memset(label, '\0', sizeof(label));
	if (ioctl(fd, BTRFS_IOC_GET_FSLABEL, label) < 0) {
		fprintf(stderr, "ERROR: unable get label %s\n", strerror(errno));
		close(fd);
		return -1;
	}

	strncpy(labelp, label, sizeof(label));
	close(fd);
	return 0;
}

int get_label(const char *btrfs_dev, char *label)
{
	int ret;

	ret = is_existing_blk_or_reg_file(btrfs_dev);
	if (!ret)
		ret = get_label_mounted(btrfs_dev, label);
	else if (ret > 0)
		ret = get_label_unmounted(btrfs_dev, label);

	return ret;
}

int set_label(const char *btrfs_dev, const char *label)
{
	int ret;

	if (check_label(label))
		return -1;

	ret = is_existing_blk_or_reg_file(btrfs_dev);
	if (!ret)
		ret = set_label_mounted(btrfs_dev, label);
	else if (ret > 0)
		ret = set_label_unmounted(btrfs_dev, label);

	return ret;
}

int btrfs_scan_block_devices(int run_ioctl)
{

	struct stat st;
	int ret;
	int fd;
	struct btrfs_fs_devices *tmp_devices;
	u64 num_devices;
	FILE *proc_partitions;
	int i;
	char buf[1024];
	char fullpath[110];
	int scans = 0;
	int special;

scan_again:
	proc_partitions = fopen("/proc/partitions","r");
	if (!proc_partitions) {
		fprintf(stderr, "Unable to open '/proc/partitions' for scanning\n");
		return -ENOENT;
	}
	/* skip the header */
	for (i = 0; i < 2; i++)
		if (!fgets(buf, 1023, proc_partitions)) {
			fprintf(stderr,
				"Unable to read '/proc/partitions' for scanning\n");
			fclose(proc_partitions);
			return -ENOENT;
		}

	strcpy(fullpath,"/dev/");
	while(fgets(buf, 1023, proc_partitions)) {
		ret = sscanf(buf," %*d %*d %*d %99s", fullpath + 5);
		if (ret != 1) {
			fprintf(stderr,
				"failed to scan device name from /proc/partitions\n");
			break;
		}

		/*
		 * multipath and MD devices may register as a btrfs filesystem
		 * both through the original block device and through
		 * the special (/dev/mapper or /dev/mdX) entry.
		 * This scans the special entries last
		 */
		special = strncmp(fullpath, "/dev/dm-", strlen("/dev/dm-")) == 0;
		if (!special)
			special = strncmp(fullpath, "/dev/md", strlen("/dev/md")) == 0;

		if (scans == 0 && special)
			continue;
		if (scans > 0 && !special)
			continue;

		ret = lstat(fullpath, &st);
		if (ret < 0) {
			fprintf(stderr, "failed to stat %s\n", fullpath);
			continue;
		}
		if (!S_ISBLK(st.st_mode)) {
			continue;
		}

		fd = open(fullpath, O_RDONLY);
		if (fd < 0) {
			if (errno != ENOMEDIUM)
				fprintf(stderr, "failed to open %s: %s\n",
					fullpath, strerror(errno));
			continue;
		}
		ret = btrfs_scan_one_device(fd, fullpath, &tmp_devices,
					    &num_devices,
					    BTRFS_SUPER_INFO_OFFSET, 0);
		if (ret == 0 && run_ioctl > 0) {
			btrfs_register_one_device(fullpath);
		}
		close(fd);
	}

	fclose(proc_partitions);

	if (scans == 0) {
		scans++;
		goto scan_again;
	}
	return 0;
}

/*
 * A not-so-good version fls64. No fascinating optimization since
 * no one except parse_size use it
 */
static int fls64(u64 x)
{
	int i;

	for (i = 0; i <64; i++)
		if (x << i & (1ULL << 63))
			return 64 - i;
	return 64 - i;
}

u64 parse_size(char *s)
{
	char c;
	char *endptr;
	u64 mult = 1;
	u64 ret;

	if (!s) {
		fprintf(stderr, "ERROR: Size value is empty\n");
		exit(1);
	}
	if (s[0] == '-') {
		fprintf(stderr,
			"ERROR: Size value '%s' is less equal than 0\n", s);
		exit(1);
	}
	ret = strtoull(s, &endptr, 10);
	if (endptr == s) {
		fprintf(stderr, "ERROR: Size value '%s' is invalid\n", s);
		exit(1);
	}
	if (endptr[0] && endptr[1]) {
		fprintf(stderr, "ERROR: Illegal suffix contains character '%c' in wrong position\n",
			endptr[1]);
		exit(1);
	}
	/*
	 * strtoll returns LLONG_MAX when overflow, if this happens,
	 * need to call strtoull to get the real size
	 */
	if (errno == ERANGE && ret == ULLONG_MAX) {
		fprintf(stderr,
			"ERROR: Size value '%s' is too large for u64\n", s);
		exit(1);
	}
	if (endptr[0]) {
		c = tolower(endptr[0]);
		switch (c) {
		case 'e':
			mult *= 1024;
			/* fallthrough */
		case 'p':
			mult *= 1024;
			/* fallthrough */
		case 't':
			mult *= 1024;
			/* fallthrough */
		case 'g':
			mult *= 1024;
			/* fallthrough */
		case 'm':
			mult *= 1024;
			/* fallthrough */
		case 'k':
			mult *= 1024;
			/* fallthrough */
		case 'b':
			break;
		default:
			fprintf(stderr, "ERROR: Unknown size descriptor '%c'\n",
				c);
			exit(1);
		}
	}
	/* Check whether ret * mult overflow */
	if (fls64(ret) + fls64(mult) - 1 > 64) {
		fprintf(stderr,
			"ERROR: Size value '%s' is too large for u64\n", s);
		exit(1);
	}
	ret *= mult;
	return ret;
}

int open_file_or_dir3(const char *fname, DIR **dirstream, int open_flags)
{
	int ret;
	struct stat st;
	int fd;

	ret = stat(fname, &st);
	if (ret < 0) {
		return -1;
	}
	if (S_ISDIR(st.st_mode)) {
		*dirstream = opendir(fname);
		if (!*dirstream)
			return -1;
		fd = dirfd(*dirstream);
	} else if (S_ISREG(st.st_mode) || S_ISLNK(st.st_mode)) {
		fd = open(fname, open_flags);
	} else {
		/*
		 * we set this on purpose, in case the caller output
		 * strerror(errno) as success
		 */
		errno = EINVAL;
		return -1;
	}
	if (fd < 0) {
		fd = -1;
		if (*dirstream)
			closedir(*dirstream);
	}
	return fd;
}

int open_file_or_dir(const char *fname, DIR **dirstream)
{
	return open_file_or_dir3(fname, dirstream, O_RDWR);
}

void close_file_or_dir(int fd, DIR *dirstream)
{
	if (dirstream)
		closedir(dirstream);
	else if (fd >= 0)
		close(fd);
}

int get_device_info(int fd, u64 devid,
		struct btrfs_ioctl_dev_info_args *di_args)
{
	int ret;

	di_args->devid = devid;
	memset(&di_args->uuid, '\0', sizeof(di_args->uuid));

	ret = ioctl(fd, BTRFS_IOC_DEV_INFO, di_args);
	return ret ? -errno : 0;
}

/*
 * For a given path, fill in the ioctl fs_ and info_ args.
 * If the path is a btrfs mountpoint, fill info for all devices.
 * If the path is a btrfs device, fill in only that device.
 *
 * The path provided must be either on a mounted btrfs fs,
 * or be a mounted btrfs device.
 *
 * Returns 0 on success, or a negative errno.
 */
int get_fs_info(char *path, struct btrfs_ioctl_fs_info_args *fi_args,
		struct btrfs_ioctl_dev_info_args **di_ret)
{
	int fd = -1;
	int ret = 0;
	int ndevs = 0;
	int i = 0;
	struct btrfs_fs_devices *fs_devices_mnt = NULL;
	struct btrfs_ioctl_dev_info_args *di_args;
	char mp[BTRFS_PATH_NAME_MAX + 1];
	DIR *dirstream = NULL;

	memset(fi_args, 0, sizeof(*fi_args));

	if (is_block_device(path)) {
		struct btrfs_super_block *disk_super;
		char buf[BTRFS_SUPER_INFO_SIZE];
		u64 devid;

		/* Ensure it's mounted, then set path to the mountpoint */
		fd = open(path, O_RDONLY);
		if (fd < 0) {
			ret = -errno;
			fprintf(stderr, "Couldn't open %s: %s\n",
				path, strerror(errno));
			goto out;
		}
		ret = check_mounted_where(fd, path, mp, sizeof(mp),
					  &fs_devices_mnt);
		if (!ret) {
			ret = -EINVAL;
			goto out;
		}
		if (ret < 0)
			goto out;
		path = mp;
		/* Only fill in this one device */
		fi_args->num_devices = 1;

		disk_super = (struct btrfs_super_block *)buf;
		ret = btrfs_read_dev_super(fd, disk_super,
					   BTRFS_SUPER_INFO_OFFSET, 0);
		if (ret < 0) {
			ret = -EIO;
			goto out;
		}
		devid = btrfs_stack_device_id(&disk_super->dev_item);

		fi_args->max_id = devid;
		i = devid;

		memcpy(fi_args->fsid, fs_devices_mnt->fsid, BTRFS_FSID_SIZE);
		close(fd);
	}

	/* at this point path must not be for a block device */
	fd = open_file_or_dir(path, &dirstream);
	if (fd < 0) {
		ret = -errno;
		goto out;
	}

	/* fill in fi_args if not just a single device */
	if (fi_args->num_devices != 1) {
		ret = ioctl(fd, BTRFS_IOC_FS_INFO, fi_args);
		if (ret < 0) {
			ret = -errno;
			goto out;
		}
	}

	if (!fi_args->num_devices)
		goto out;

	di_args = *di_ret = malloc((fi_args->num_devices) * sizeof(*di_args));
	if (!di_args) {
		ret = -errno;
		goto out;
	}

	for (; i <= fi_args->max_id; ++i) {
		BUG_ON(ndevs >= fi_args->num_devices);
		ret = get_device_info(fd, i, &di_args[ndevs]);
		if (ret == -ENODEV)
			continue;
		if (ret)
			goto out;
		ndevs++;
	}

	/*
	* only when the only dev we wanted to find is not there then
	* let any error be returned
	*/
	if (fi_args->num_devices != 1) {
		BUG_ON(ndevs == 0);
		ret = 0;
	}

out:
	close_file_or_dir(fd, dirstream);
	return ret;
}

#define isoctal(c)	(((c) & ~7) == '0')

static inline void translate(char *f, char *t)
{
	while (*f != '\0') {
		if (*f == '\\' &&
		    isoctal(f[1]) && isoctal(f[2]) && isoctal(f[3])) {
			*t++ = 64*(f[1] & 7) + 8*(f[2] & 7) + (f[3] & 7);
			f += 4;
		} else
			*t++ = *f++;
	}
	*t = '\0';
	return;
}

/*
 * Checks if the swap device.
 * Returns 1 if swap device, < 0 on error or 0 if not swap device.
 */
static int is_swap_device(const char *file)
{
	FILE	*f;
	struct stat	st_buf;
	dev_t	dev;
	ino_t	ino = 0;
	char	tmp[PATH_MAX];
	char	buf[PATH_MAX];
	char	*cp;
	int	ret = 0;

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

	if ((f = fopen("/proc/swaps", "r")) == NULL)
		return 0;

	/* skip the first line */
	if (fgets(tmp, sizeof(tmp), f) == NULL)
		goto out;

	while (fgets(tmp, sizeof(tmp), f) != NULL) {
		if ((cp = strchr(tmp, ' ')) != NULL)
			*cp = '\0';
		if ((cp = strchr(tmp, '\t')) != NULL)
			*cp = '\0';
		translate(tmp, buf);
		if (stat(buf, &st_buf) != 0)
			continue;
		if (S_ISBLK(st_buf.st_mode)) {
			if (dev == st_buf.st_rdev) {
				ret = 1;
				break;
			}
		} else if (S_ISREG(st_buf.st_mode)) {
			if (dev == st_buf.st_dev && ino == st_buf.st_ino) {
				ret = 1;
				break;
			}
		}
	}

out:
	fclose(f);

	return ret;
}

/*
 * Check for existing filesystem or partition table on device.
 * Returns:
 *	 1 for existing fs or partition
 *	 0 for nothing found
 *	-1 for internal error
 */
static int
check_overwrite(
	char		*device)
{
	const char	*type;
	blkid_probe	pr = NULL;
	int		ret;
	blkid_loff_t	size;

	if (!device || !*device)
		return 0;

	ret = -1; /* will reset on success of all setup calls */

	pr = blkid_new_probe_from_filename(device);
	if (!pr)
		goto out;

	size = blkid_probe_get_size(pr);
	if (size < 0)
		goto out;

	/* nothing to overwrite on a 0-length device */
	if (size == 0) {
		ret = 0;
		goto out;
	}

	ret = blkid_probe_enable_partitions(pr, 1);
	if (ret < 0)
		goto out;

	ret = blkid_do_fullprobe(pr);
	if (ret < 0)
		goto out;

	/*
	 * Blkid returns 1 for nothing found and 0 when it finds a signature,
	 * but we want the exact opposite, so reverse the return value here.
	 *
	 * In addition print some useful diagnostics about what actually is
	 * on the device.
	 */
	if (ret) {
		ret = 0;
		goto out;
	}

	if (!blkid_probe_lookup_value(pr, "TYPE", &type, NULL)) {
		fprintf(stderr,
			"%s appears to contain an existing "
			"filesystem (%s).\n", device, type);
	} else if (!blkid_probe_lookup_value(pr, "PTTYPE", &type, NULL)) {
		fprintf(stderr,
			"%s appears to contain a partition "
			"table (%s).\n", device, type);
	} else {
		fprintf(stderr,
			"%s appears to contain something weird "
			"according to blkid\n", device);
	}
	ret = 1;

out:
	if (pr)
		blkid_free_probe(pr);
	if (ret == -1)
		fprintf(stderr,
			"probe of %s failed, cannot detect "
			  "existing filesystem.\n", device);
	return ret;
}

static int group_profile_devs_min(u64 flag)
{
	switch (flag & BTRFS_BLOCK_GROUP_PROFILE_MASK) {
	case 0: /* single */
	case BTRFS_BLOCK_GROUP_DUP:
		return 1;
	case BTRFS_BLOCK_GROUP_RAID0:
	case BTRFS_BLOCK_GROUP_RAID1:
	case BTRFS_BLOCK_GROUP_RAID5:
		return 2;
	case BTRFS_BLOCK_GROUP_RAID6:
		return 3;
	case BTRFS_BLOCK_GROUP_RAID10:
		return 4;
	default:
		return -1;
	}
}

int test_num_disk_vs_raid(u64 metadata_profile, u64 data_profile,
	u64 dev_cnt, int mixed, char *estr)
{
	size_t sz = 100;
	u64 allowed = 0;

	switch (dev_cnt) {
	default:
	case 4:
		allowed |= BTRFS_BLOCK_GROUP_RAID10;
	case 3:
		allowed |= BTRFS_BLOCK_GROUP_RAID6;
	case 2:
		allowed |= BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1 |
			BTRFS_BLOCK_GROUP_RAID5;
		break;
	case 1:
		allowed |= BTRFS_BLOCK_GROUP_DUP;
	}

	if (dev_cnt > 1 &&
	    ((metadata_profile | data_profile) & BTRFS_BLOCK_GROUP_DUP)) {
		snprintf(estr, sz,
			"DUP is not allowed when FS has multiple devices\n");
		return 1;
	}
	if (metadata_profile & ~allowed) {
		snprintf(estr, sz,
			"unable to create FS with metadata profile %s "
			"(have %llu devices but %d devices are required)\n",
			btrfs_group_profile_str(metadata_profile), dev_cnt,
			group_profile_devs_min(metadata_profile));
		return 1;
	}
	if (data_profile & ~allowed) {
		snprintf(estr, sz,
			"unable to create FS with data profile %s "
			"(have %llu devices but %d devices are required)\n",
			btrfs_group_profile_str(data_profile), dev_cnt,
			group_profile_devs_min(data_profile));
		return 1;
	}

	if (!mixed && (data_profile & BTRFS_BLOCK_GROUP_DUP)) {
		snprintf(estr, sz,
			"dup for data is allowed only in mixed mode");
		return 1;
	}
	return 0;
}

/* Check if disk is suitable for btrfs
 * returns:
 *  1: something is wrong, estr provides the error
 *  0: all is fine
 */
int test_dev_for_mkfs(char *file, int force_overwrite, char *estr)
{
	int ret, fd;
	size_t sz = 100;
	struct stat st;

	ret = is_swap_device(file);
	if (ret < 0) {
		snprintf(estr, sz, "error checking %s status: %s\n", file,
			strerror(-ret));
		return 1;
	}
	if (ret == 1) {
		snprintf(estr, sz, "%s is a swap device\n", file);
		return 1;
	}
	if (!force_overwrite) {
		if (check_overwrite(file)) {
			snprintf(estr, sz, "Use the -f option to force overwrite.\n");
			return 1;
		}
	}
	ret = check_mounted(file);
	if (ret < 0) {
		snprintf(estr, sz, "error checking %s mount status\n",
			file);
		return 1;
	}
	if (ret == 1) {
		snprintf(estr, sz, "%s is mounted\n", file);
		return 1;
	}
	/* check if the device is busy */
	fd = open(file, O_RDWR|O_EXCL);
	if (fd < 0) {
		snprintf(estr, sz, "unable to open %s: %s\n", file,
			strerror(errno));
		return 1;
	}
	if (fstat(fd, &st)) {
		snprintf(estr, sz, "unable to stat %s: %s\n", file,
			strerror(errno));
		close(fd);
		return 1;
	}
	if (!S_ISBLK(st.st_mode)) {
		fprintf(stderr, "'%s' is not a block device\n", file);
		close(fd);
		return 1;
	}
	close(fd);
	return 0;
}

int btrfs_scan_lblkid()
{
	int fd = -1;
	int ret;
	u64 num_devices;
	struct btrfs_fs_devices *tmp_devices;
	blkid_dev_iterate iter = NULL;
	blkid_dev dev = NULL;
	blkid_cache cache = NULL;
	char path[PATH_MAX];

	if (btrfs_scan_done)
		return 0;

	if (blkid_get_cache(&cache, 0) < 0) {
		printf("ERROR: lblkid cache get failed\n");
		return 1;
	}
	blkid_probe_all(cache);
	iter = blkid_dev_iterate_begin(cache);
	blkid_dev_set_search(iter, "TYPE", "btrfs");
	while (blkid_dev_next(iter, &dev) == 0) {
		dev = blkid_verify(cache, dev);
		if (!dev)
			continue;
		/* if we are here its definitely a btrfs disk*/
		strncpy(path, blkid_dev_devname(dev), PATH_MAX);

		fd = open(path, O_RDONLY);
		if (fd < 0) {
			printf("ERROR: could not open %s\n", path);
			continue;
		}
		ret = btrfs_scan_one_device(fd, path, &tmp_devices,
				&num_devices, BTRFS_SUPER_INFO_OFFSET, 0);
		if (ret) {
			printf("ERROR: could not scan %s\n", path);
			close (fd);
			continue;
		}

		close(fd);
	}
	blkid_dev_iterate_end(iter);
	blkid_put_cache(cache);

	btrfs_scan_done = 1;

	return 0;
}

int is_vol_small(char *file)
{
	int fd = -1;
	int e;
	struct stat st;
	u64 size;

	fd = open(file, O_RDONLY);
	if (fd < 0)
		return -errno;
	if (fstat(fd, &st) < 0) {
		e = -errno;
		close(fd);
		return e;
	}
	size = btrfs_device_size(fd, &st);
	if (size == 0) {
		close(fd);
		return -1;
	}
	if (size < BTRFS_MKFS_SMALL_VOLUME_SIZE) {
		close(fd);
		return 1;
	} else {
		close(fd);
		return 0;
	}
}

/*
 * This reads a line from the stdin and only returns non-zero if the
 * first whitespace delimited token is a case insensitive match with yes
 * or y.
 */
int ask_user(char *question)
{
	char buf[30] = {0,};
	char *saveptr = NULL;
	char *answer;

	printf("%s [y/N]: ", question);

	return fgets(buf, sizeof(buf) - 1, stdin) &&
	       (answer = strtok_r(buf, " \t\n\r", &saveptr)) &&
	       (!strcasecmp(answer, "yes") || !strcasecmp(answer, "y"));
}

/*
 * For a given:
 * - file or directory return the containing tree root id
 * - subvolume return its own tree id
 * - BTRFS_EMPTY_SUBVOL_DIR_OBJECTID (directory with ino == 2) the result is
 *   undefined and function returns -1
 */
int lookup_ino_rootid(int fd, u64 *rootid)
{
	struct btrfs_ioctl_ino_lookup_args args;
	int ret;
	int e;

	memset(&args, 0, sizeof(args));
	args.treeid = 0;
	args.objectid = BTRFS_FIRST_FREE_OBJECTID;

	ret = ioctl(fd, BTRFS_IOC_INO_LOOKUP, &args);
	e = errno;
	if (ret) {
		fprintf(stderr, "ERROR: Failed to lookup root id - %s\n",
			strerror(e));
		return ret;
	}

	*rootid = args.treeid;

	return 0;
}

/*
 * return 0 if a btrfs mount point is found
 * return 1 if a mount point is found but not btrfs
 * return <0 if something goes wrong
 */
int find_mount_root(const char *path, char **mount_root)
{
	FILE *mnttab;
	int fd;
	struct mntent *ent;
	int len;
	int ret;
	int not_btrfs = 1;
	int longest_matchlen = 0;
	char *longest_match = NULL;

	fd = open(path, O_RDONLY | O_NOATIME);
	if (fd < 0)
		return -errno;
	close(fd);

	mnttab = setmntent("/proc/self/mounts", "r");
	if (!mnttab)
		return -errno;

	while ((ent = getmntent(mnttab))) {
		len = strlen(ent->mnt_dir);
		if (strncmp(ent->mnt_dir, path, len) == 0) {
			/* match found and use the latest match */
			if (longest_matchlen <= len) {
				free(longest_match);
				longest_matchlen = len;
				longest_match = strdup(ent->mnt_dir);
				not_btrfs = strcmp(ent->mnt_type, "btrfs");
			}
		}
	}
	endmntent(mnttab);

	if (!longest_match)
		return -ENOENT;
	if (not_btrfs) {
		free(longest_match);
		return 1;
	}

	ret = 0;
	*mount_root = realpath(longest_match, NULL);
	if (!*mount_root)
		ret = -errno;

	free(longest_match);
	return ret;
}

int test_minimum_size(const char *file, u32 leafsize)
{
	int fd;
	struct stat statbuf;

	fd = open(file, O_RDONLY);
	if (fd < 0)
		return -errno;
	if (stat(file, &statbuf) < 0) {
		close(fd);
		return -errno;
	}
	if (btrfs_device_size(fd, &statbuf) < btrfs_min_dev_size(leafsize)) {
		close(fd);
		return 1;
	}
	close(fd);
	return 0;
}

/*
 * test if name is a correct subvolume name
 * this function return
 * 0-> name is not a correct subvolume name
 * 1-> name is a correct subvolume name
 */
int test_issubvolname(const char *name)
{
	return name[0] != '\0' && !strchr(name, '/') &&
		strcmp(name, ".") && strcmp(name, "..");
}

/*
 * test if path is a directory
 * this function return
 * 0-> path exists but it is not a directory
 * 1-> path exists and it is a directory
 * -1 -> path is unaccessible
 */
int test_isdir(const char *path)
{
	struct stat st;
	int ret;

	ret = stat(path, &st);
	if(ret < 0 )
		return -1;

	return S_ISDIR(st.st_mode);
}

void units_set_mode(unsigned *units, unsigned mode)
{
	unsigned base = *units & UNITS_MODE_MASK;

	*units = base | mode;
}

void units_set_base(unsigned *units, unsigned base)
{
	unsigned mode = *units & ~UNITS_MODE_MASK;

	*units = base | mode;
}

int find_next_key(struct btrfs_path *path, struct btrfs_key *key)
{
	int level;

	for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
		if (!path->nodes[level])
			break;
		if (path->slots[level] + 1 >=
		    btrfs_header_nritems(path->nodes[level]))
			continue;
		if (level == 0)
			btrfs_item_key_to_cpu(path->nodes[level], key,
					      path->slots[level] + 1);
		else
			btrfs_node_key_to_cpu(path->nodes[level], key,
					      path->slots[level] + 1);
		return 0;
	}
	return 1;
}

char* btrfs_group_type_str(u64 flag)
{
	u64 mask = BTRFS_BLOCK_GROUP_TYPE_MASK |
		BTRFS_SPACE_INFO_GLOBAL_RSV;

	switch (flag & mask) {
	case BTRFS_BLOCK_GROUP_DATA:
		return "Data";
	case BTRFS_BLOCK_GROUP_SYSTEM:
		return "System";
	case BTRFS_BLOCK_GROUP_METADATA:
		return "Metadata";
	case BTRFS_BLOCK_GROUP_DATA|BTRFS_BLOCK_GROUP_METADATA:
		return "Data+Metadata";
	case BTRFS_SPACE_INFO_GLOBAL_RSV:
		return "GlobalReserve";
	default:
		return "unknown";
	}
}

char* btrfs_group_profile_str(u64 flag)
{
	switch (flag & BTRFS_BLOCK_GROUP_PROFILE_MASK) {
	case 0:
		return "single";
	case BTRFS_BLOCK_GROUP_RAID0:
		return "RAID0";
	case BTRFS_BLOCK_GROUP_RAID1:
		return "RAID1";
	case BTRFS_BLOCK_GROUP_RAID5:
		return "RAID5";
	case BTRFS_BLOCK_GROUP_RAID6:
		return "RAID6";
	case BTRFS_BLOCK_GROUP_DUP:
		return "DUP";
	case BTRFS_BLOCK_GROUP_RAID10:
		return "RAID10";
	default:
		return "unknown";
	}
}

u64 disk_size(char *path)
{
	struct statfs sfs;

	if (statfs(path, &sfs) < 0)
		return 0;
	else
		return sfs.f_bsize * sfs.f_blocks;
}

u64 get_partition_size(char *dev)
{
	u64 result;
	int fd = open(dev, O_RDONLY);

	if (fd < 0)
		return 0;
	if (ioctl(fd, BLKGETSIZE64, &result) < 0) {
		close(fd);
		return 0;
	}
	close(fd);

	return result;
}