btrfs-progs: Introduce function to initialize csum tree

[platform/upstream/btrfs-progs.git] / 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.
 */

#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 <sys/statfs.h>
#include <linux/magic.h>
#include <getopt.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"
#include "commands.h"

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

static int btrfs_scan_done = 0;

static char argv0_buf[ARGV0_BUF_SIZE] = "btrfs";

static int rand_seed_initlized = 0;
static unsigned short rand_seed[3];

const char *get_argv0_buf(void)
{
        return argv0_buf;
}

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, NULL) < 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;
}

/*
 * Reserve space from free_tree.
 * The algorithm is very simple, find the first cache_extent with enough space
 * and allocate from its beginning.
 */
static int reserve_free_space(struct cache_tree *free_tree, u64 len,
                              u64 *ret_start)
{
        struct cache_extent *cache;
        int found = 0;

        BUG_ON(!ret_start);
        cache = first_cache_extent(free_tree);
        while (cache) {
                if (cache->size > len) {
                        found = 1;
                        *ret_start = cache->start;

                        cache->size -= len;
                        if (cache->size == 0) {
                                remove_cache_extent(free_tree, cache);
                                free(cache);
                        } else {
                                cache->start += len;
                        }
                        break;
                }
                cache = next_cache_extent(cache);
        }
        if (!found)
                return -ENOSPC;
        return 0;
}

static inline int write_temp_super(int fd, struct btrfs_super_block *sb,
                                   u64 sb_bytenr)
{
        u32 crc = ~(u32)0;
        int ret;

        crc = btrfs_csum_data(NULL, (char *)sb + BTRFS_CSUM_SIZE, crc,
                              BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE);
        btrfs_csum_final(crc, (char *)&sb->csum[0]);
        ret = pwrite(fd, sb, BTRFS_SUPER_INFO_SIZE, sb_bytenr);
        if (ret < BTRFS_SUPER_INFO_SIZE)
                ret = (ret < 0 ? -errno : -EIO);
        else
                ret = 0;
        return ret;
}

/*
 * Setup temporary superblock at cfg->super_bynter
 * Needed info are extracted from cfg, and root_bytenr, chunk_bytenr
 *
 * For now sys chunk array will be empty and dev_item is empty too.
 * They will be re-initialized at temp chunk tree setup.
 */
static int setup_temp_super(int fd, struct btrfs_mkfs_config *cfg,
                            u64 root_bytenr, u64 chunk_bytenr)
{
        unsigned char chunk_uuid[BTRFS_UUID_SIZE];
        char super_buf[BTRFS_SUPER_INFO_SIZE];
        struct btrfs_super_block *super = (struct btrfs_super_block *)super_buf;
        int ret;

        /*
         * We rely on cfg->chunk_uuid and cfg->fs_uuid to pass uuid
         * for other functions.
         * Caller must allocate space for them
         */
        BUG_ON(!cfg->chunk_uuid || !cfg->fs_uuid);
        memset(super_buf, 0, BTRFS_SUPER_INFO_SIZE);
        cfg->num_bytes = round_down(cfg->num_bytes, cfg->sectorsize);

        if (cfg->fs_uuid && *cfg->fs_uuid) {
                if (uuid_parse(cfg->fs_uuid, super->fsid) != 0) {
                        error("cound not parse UUID: %s", cfg->fs_uuid);
                        ret = -EINVAL;
                        goto out;
                }
                if (!test_uuid_unique(cfg->fs_uuid)) {
                        error("non-unique UUID: %s", cfg->fs_uuid);
                        ret = -EINVAL;
                        goto out;
                }
        } else {
                uuid_generate(super->fsid);
                uuid_unparse(super->fsid, cfg->fs_uuid);
        }
        uuid_generate(chunk_uuid);
        uuid_unparse(chunk_uuid, cfg->chunk_uuid);

        btrfs_set_super_bytenr(super, cfg->super_bytenr);
        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, root_bytenr);
        btrfs_set_super_chunk_root(super, chunk_bytenr);
        btrfs_set_super_total_bytes(super, cfg->num_bytes);
        /*
         * Temporary filesystem will only have 6 tree roots:
         * chunk tree, root tree, extent_tree, device tree, fs tree
         * and csum tree.
         */
        btrfs_set_super_bytes_used(super, 6 * cfg->nodesize);
        btrfs_set_super_sectorsize(super, cfg->sectorsize);
        btrfs_set_super_leafsize(super, cfg->nodesize);
        btrfs_set_super_nodesize(super, cfg->nodesize);
        btrfs_set_super_stripesize(super, cfg->stripesize);
        btrfs_set_super_csum_type(super, BTRFS_CSUM_TYPE_CRC32);
        btrfs_set_super_chunk_root(super, chunk_bytenr);
        btrfs_set_super_cache_generation(super, -1);
        btrfs_set_super_incompat_flags(super, cfg->features);
        if (cfg->label)
                __strncpy_null(super->label, cfg->label, BTRFS_LABEL_SIZE - 1);

        /* Sys chunk array will be re-initialized at chunk tree init time */
        super->sys_chunk_array_size = 0;

        ret = write_temp_super(fd, super, cfg->super_bytenr);
out:
        return ret;
}

/*
 * Setup an extent buffer for tree block.
 */
static int setup_temp_extent_buffer(struct extent_buffer *buf,
                                    struct btrfs_mkfs_config *cfg,
                                    u64 bytenr, u64 owner)
{
        unsigned char fsid[BTRFS_FSID_SIZE];
        unsigned char chunk_uuid[BTRFS_UUID_SIZE];
        int ret;

        /* We rely on cfg->fs_uuid and chunk_uuid to fsid and chunk uuid */
        BUG_ON(!cfg->fs_uuid || !cfg->chunk_uuid);
        ret = uuid_parse(cfg->fs_uuid, fsid);
        if (ret)
                return -EINVAL;
        ret = uuid_parse(cfg->chunk_uuid, chunk_uuid);
        if (ret)
                return -EINVAL;

        memset(buf->data, 0, cfg->nodesize);
        buf->len = cfg->nodesize;
        btrfs_set_header_bytenr(buf, bytenr);
        btrfs_set_header_generation(buf, 1);
        btrfs_set_header_backref_rev(buf, BTRFS_MIXED_BACKREF_REV);
        btrfs_set_header_owner(buf, owner);
        btrfs_set_header_flags(buf, BTRFS_HEADER_FLAG_WRITTEN);
        write_extent_buffer(buf, chunk_uuid, btrfs_header_chunk_tree_uuid(buf),
                            BTRFS_UUID_SIZE);
        write_extent_buffer(buf, fsid, btrfs_header_fsid(), BTRFS_FSID_SIZE);
        return 0;
}

static inline int write_temp_extent_buffer(int fd, struct extent_buffer *buf,
                                           u64 bytenr)
{
        int ret;

        csum_tree_block_size(buf, BTRFS_CRC32_SIZE, 0);

        /* Temporary extent buffer is always mapped 1:1 on disk */
        ret = pwrite(fd, buf->data, buf->len, bytenr);
        if (ret < buf->len)
                ret = (ret < 0 ? ret : -EIO);
        else
                ret = 0;
        return ret;
}

/*
 * Insert a root item for temporary tree root
 *
 * Only used in make_btrfs_v2().
 */
static void insert_temp_root_item(struct extent_buffer *buf,
                                  struct btrfs_mkfs_config *cfg,
                                  int *slot, u32 *itemoff, u64 objectid,
                                  u64 bytenr)
{
        struct btrfs_root_item root_item;
        struct btrfs_inode_item *inode_item;
        struct btrfs_disk_key disk_key;

        btrfs_set_header_nritems(buf, *slot + 1);
        (*itemoff) -= sizeof(root_item);
        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, cfg->nodesize);
        btrfs_set_stack_inode_mode(inode_item, S_IFDIR | 0755);
        btrfs_set_root_refs(&root_item, 1);
        btrfs_set_root_used(&root_item, cfg->nodesize);
        btrfs_set_root_generation(&root_item, 1);
        btrfs_set_root_bytenr(&root_item, bytenr);

        memset(&disk_key, 0, sizeof(disk_key));
        btrfs_set_disk_key_type(&disk_key, BTRFS_ROOT_ITEM_KEY);
        btrfs_set_disk_key_objectid(&disk_key, objectid);
        btrfs_set_disk_key_offset(&disk_key, 0);

        btrfs_set_item_key(buf, &disk_key, *slot);
        btrfs_set_item_offset(buf, btrfs_item_nr(*slot), *itemoff);
        btrfs_set_item_size(buf, btrfs_item_nr(*slot), sizeof(root_item));
        write_extent_buffer(buf, &root_item,
                            btrfs_item_ptr_offset(buf, *slot),
                            sizeof(root_item));
        (*slot)++;
}

static int setup_temp_root_tree(int fd, struct btrfs_mkfs_config *cfg,
                                u64 root_bytenr, u64 extent_bytenr,
                                u64 dev_bytenr, u64 fs_bytenr, u64 csum_bytenr)
{
        struct extent_buffer *buf = NULL;
        u32 itemoff = __BTRFS_LEAF_DATA_SIZE(cfg->nodesize);
        int slot = 0;
        int ret;

        /*
         * Provided bytenr must in ascending order, or tree root will have a
         * bad key order.
         */
        BUG_ON(!(root_bytenr < extent_bytenr && extent_bytenr < dev_bytenr &&
                 dev_bytenr < fs_bytenr && fs_bytenr < csum_bytenr));
        buf = malloc(sizeof(*buf) + cfg->nodesize);
        if (!buf)
                return -ENOMEM;

        ret = setup_temp_extent_buffer(buf, cfg, root_bytenr,
                                       BTRFS_ROOT_TREE_OBJECTID);
        if (ret < 0)
                goto out;

        insert_temp_root_item(buf, cfg, &slot, &itemoff,
                              BTRFS_EXTENT_TREE_OBJECTID, extent_bytenr);
        insert_temp_root_item(buf, cfg, &slot, &itemoff,
                              BTRFS_DEV_TREE_OBJECTID, dev_bytenr);
        insert_temp_root_item(buf, cfg, &slot, &itemoff,
                              BTRFS_FS_TREE_OBJECTID, fs_bytenr);
        insert_temp_root_item(buf, cfg, &slot, &itemoff,
                              BTRFS_CSUM_TREE_OBJECTID, csum_bytenr);

        ret = write_temp_extent_buffer(fd, buf, root_bytenr);
out:
        free(buf);
        return ret;
}

static int insert_temp_dev_item(int fd, struct extent_buffer *buf,
                                struct btrfs_mkfs_config *cfg,
                                int *slot, u32 *itemoff)
{
        struct btrfs_disk_key disk_key;
        struct btrfs_dev_item *dev_item;
        char super_buf[BTRFS_SUPER_INFO_SIZE];
        unsigned char dev_uuid[BTRFS_UUID_SIZE];
        unsigned char fsid[BTRFS_FSID_SIZE];
        struct btrfs_super_block *super = (struct btrfs_super_block *)super_buf;
        int ret;

        ret = pread(fd, super_buf, BTRFS_SUPER_INFO_SIZE, cfg->super_bytenr);
        if (ret < BTRFS_SUPER_INFO_SIZE) {
                ret = (ret < 0 ? -errno : -EIO);
                goto out;
        }

        btrfs_set_header_nritems(buf, *slot + 1);
        (*itemoff) -= sizeof(*dev_item);
        /* setup device item 1, 0 is for replace case */
        btrfs_set_disk_key_type(&disk_key, BTRFS_DEV_ITEM_KEY);
        btrfs_set_disk_key_objectid(&disk_key, BTRFS_DEV_ITEMS_OBJECTID);
        btrfs_set_disk_key_offset(&disk_key, 1);
        btrfs_set_item_key(buf, &disk_key, *slot);
        btrfs_set_item_offset(buf, btrfs_item_nr(*slot), *itemoff);
        btrfs_set_item_size(buf, btrfs_item_nr(*slot), sizeof(*dev_item));

        dev_item = btrfs_item_ptr(buf, *slot, struct btrfs_dev_item);
        /* Generate device uuid */
        uuid_generate(dev_uuid);
        write_extent_buffer(buf, dev_uuid,
                        (unsigned long)btrfs_device_uuid(dev_item),
                        BTRFS_UUID_SIZE);
        uuid_parse(cfg->fs_uuid, fsid);
        write_extent_buffer(buf, fsid,
                        (unsigned long)btrfs_device_fsid(dev_item),
                        BTRFS_FSID_SIZE);
        btrfs_set_device_id(buf, dev_item, 1);
        btrfs_set_device_generation(buf, dev_item, 0);
        btrfs_set_device_total_bytes(buf, dev_item, cfg->num_bytes);
        /*
         * The number must match the initial SYSTEM and META chunk size
         */
        btrfs_set_device_bytes_used(buf, dev_item,
                        BTRFS_MKFS_SYSTEM_GROUP_SIZE +
                        BTRFS_CONVERT_META_GROUP_SIZE);
        btrfs_set_device_io_align(buf, dev_item, cfg->sectorsize);
        btrfs_set_device_io_width(buf, dev_item, cfg->sectorsize);
        btrfs_set_device_sector_size(buf, dev_item, cfg->sectorsize);
        btrfs_set_device_type(buf, dev_item, 0);

        /* Super dev_item is not complete, copy the complete one to sb */
        read_extent_buffer(buf, &super->dev_item, (unsigned long)dev_item,
                           sizeof(*dev_item));
        ret = write_temp_super(fd, super, cfg->super_bytenr);
        (*slot)++;
out:
        return ret;
}

static int insert_temp_chunk_item(int fd, struct extent_buffer *buf,
                                  struct btrfs_mkfs_config *cfg,
                                  int *slot, u32 *itemoff, u64 start, u64 len,
                                  u64 type)
{
        struct btrfs_chunk *chunk;
        struct btrfs_disk_key disk_key;
        char super_buf[BTRFS_SUPER_INFO_SIZE];
        struct btrfs_super_block *sb = (struct btrfs_super_block *)super_buf;
        int ret = 0;

        ret = pread(fd, super_buf, BTRFS_SUPER_INFO_SIZE,
                    cfg->super_bytenr);
        if (ret < BTRFS_SUPER_INFO_SIZE) {
                ret = (ret < 0 ? ret : -EIO);
                return ret;
        }

        btrfs_set_header_nritems(buf, *slot + 1);
        (*itemoff) -= btrfs_chunk_item_size(1);
        btrfs_set_disk_key_type(&disk_key, BTRFS_CHUNK_ITEM_KEY);
        btrfs_set_disk_key_objectid(&disk_key, BTRFS_FIRST_CHUNK_TREE_OBJECTID);
        btrfs_set_disk_key_offset(&disk_key, start);
        btrfs_set_item_key(buf, &disk_key, *slot);
        btrfs_set_item_offset(buf, btrfs_item_nr(*slot), *itemoff);
        btrfs_set_item_size(buf, btrfs_item_nr(*slot),
                            btrfs_chunk_item_size(1));

        chunk = btrfs_item_ptr(buf, *slot, struct btrfs_chunk);
        btrfs_set_chunk_length(buf, chunk, len);
        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, type);
        btrfs_set_chunk_io_align(buf, chunk, cfg->sectorsize);
        btrfs_set_chunk_io_width(buf, chunk, cfg->sectorsize);
        btrfs_set_chunk_sector_size(buf, chunk, cfg->sectorsize);
        btrfs_set_chunk_num_stripes(buf, chunk, 1);
        /* TODO: Support DUP profile for system chunk */
        btrfs_set_stripe_devid_nr(buf, chunk, 0, 1);
        /* We are doing 1:1 mapping, so start is its dev offset */
        btrfs_set_stripe_offset_nr(buf, chunk, 0, start);
        write_extent_buffer(buf, &sb->dev_item.uuid,
                            (unsigned long)btrfs_stripe_dev_uuid_nr(chunk, 0),
                            BTRFS_UUID_SIZE);
        (*slot)++;

        /*
         * If it's system chunk, also copy it to super block.
         */
        if (type & BTRFS_BLOCK_GROUP_SYSTEM) {
                char *cur;

                cur = (char *)sb->sys_chunk_array + sb->sys_chunk_array_size;
                memcpy(cur, &disk_key, sizeof(disk_key));
                cur += sizeof(disk_key);
                read_extent_buffer(buf, cur, (unsigned long int)chunk,
                                   btrfs_chunk_item_size(1));
                sb->sys_chunk_array_size += btrfs_chunk_item_size(1) +
                                            sizeof(disk_key);

                ret = write_temp_super(fd, sb, cfg->super_bytenr);
        }
        return ret;
}

static int setup_temp_chunk_tree(int fd, struct btrfs_mkfs_config *cfg,
                                 u64 sys_chunk_start, u64 meta_chunk_start,
                                 u64 chunk_bytenr)
{
        struct extent_buffer *buf = NULL;
        u32 itemoff = __BTRFS_LEAF_DATA_SIZE(cfg->nodesize);
        int slot = 0;
        int ret;

        /* Must ensure SYS chunk starts before META chunk */
        BUG_ON(meta_chunk_start < sys_chunk_start);
        buf = malloc(sizeof(*buf) + cfg->nodesize);
        if (!buf)
                return -ENOMEM;
        ret = setup_temp_extent_buffer(buf, cfg, chunk_bytenr,
                                       BTRFS_CHUNK_TREE_OBJECTID);
        if (ret < 0)
                goto out;

        ret = insert_temp_dev_item(fd, buf, cfg, &slot, &itemoff);
        if (ret < 0)
                goto out;
        ret = insert_temp_chunk_item(fd, buf, cfg, &slot, &itemoff,
                                     sys_chunk_start,
                                     BTRFS_MKFS_SYSTEM_GROUP_SIZE,
                                     BTRFS_BLOCK_GROUP_SYSTEM);
        if (ret < 0)
                goto out;
        ret = insert_temp_chunk_item(fd, buf, cfg, &slot, &itemoff,
                                     meta_chunk_start,
                                     BTRFS_CONVERT_META_GROUP_SIZE,
                                     BTRFS_BLOCK_GROUP_METADATA);
        if (ret < 0)
                goto out;
        ret = write_temp_extent_buffer(fd, buf, chunk_bytenr);

out:
        free(buf);
        return ret;
}

static void insert_temp_dev_extent(struct extent_buffer *buf,
                                   int *slot, u32 *itemoff, u64 start, u64 len)
{
        struct btrfs_dev_extent *dev_extent;
        struct btrfs_disk_key disk_key;

        btrfs_set_header_nritems(buf, *slot + 1);
        (*itemoff) -= sizeof(*dev_extent);
        btrfs_set_disk_key_type(&disk_key, BTRFS_DEV_EXTENT_KEY);
        btrfs_set_disk_key_objectid(&disk_key, 1);
        btrfs_set_disk_key_offset(&disk_key, start);
        btrfs_set_item_key(buf, &disk_key, *slot);
        btrfs_set_item_offset(buf, btrfs_item_nr(*slot), *itemoff);
        btrfs_set_item_size(buf, btrfs_item_nr(*slot), sizeof(*dev_extent));

        dev_extent = btrfs_item_ptr(buf, *slot, struct btrfs_dev_extent);
        btrfs_set_dev_extent_chunk_objectid(buf, dev_extent,
                                            BTRFS_FIRST_CHUNK_TREE_OBJECTID);
        btrfs_set_dev_extent_length(buf, dev_extent, len);
        btrfs_set_dev_extent_chunk_offset(buf, dev_extent, start);
        btrfs_set_dev_extent_chunk_tree(buf, dev_extent,
                                        BTRFS_CHUNK_TREE_OBJECTID);
        (*slot)++;
}

static int setup_temp_dev_tree(int fd, struct btrfs_mkfs_config *cfg,
                               u64 sys_chunk_start, u64 meta_chunk_start,
                               u64 dev_bytenr)
{
        struct extent_buffer *buf = NULL;
        u32 itemoff = __BTRFS_LEAF_DATA_SIZE(cfg->nodesize);
        int slot = 0;
        int ret;

        /* Must ensure SYS chunk starts before META chunk */
        BUG_ON(meta_chunk_start < sys_chunk_start);
        buf = malloc(sizeof(*buf) + cfg->nodesize);
        if (!buf)
                return -ENOMEM;
        ret = setup_temp_extent_buffer(buf, cfg, dev_bytenr,
                                       BTRFS_DEV_TREE_OBJECTID);
        if (ret < 0)
                goto out;
        insert_temp_dev_extent(buf, &slot, &itemoff, sys_chunk_start,
                               BTRFS_MKFS_SYSTEM_GROUP_SIZE);
        insert_temp_dev_extent(buf, &slot, &itemoff, meta_chunk_start,
                               BTRFS_CONVERT_META_GROUP_SIZE);
        ret = write_temp_extent_buffer(fd, buf, dev_bytenr);
out:
        free(buf);
        return ret;
}

static int setup_temp_fs_tree(int fd, struct btrfs_mkfs_config *cfg,
                              u64 fs_bytenr)
{
        struct extent_buffer *buf = NULL;
        int ret;

        buf = malloc(sizeof(*buf) + cfg->nodesize);
        if (!buf)
                return -ENOMEM;
        ret = setup_temp_extent_buffer(buf, cfg, fs_bytenr,
                                       BTRFS_FS_TREE_OBJECTID);
        if (ret < 0)
                goto out;
        /*
         * Temporary fs tree is completely empty.
         */
        ret = write_temp_extent_buffer(fd, buf, fs_bytenr);
out:
        free(buf);
        return ret;
}

static int setup_temp_csum_tree(int fd, struct btrfs_mkfs_config *cfg,
                                u64 csum_bytenr)
{
        struct extent_buffer *buf = NULL;
        int ret;

        buf = malloc(sizeof(*buf) + cfg->nodesize);
        if (!buf)
                return -ENOMEM;
        ret = setup_temp_extent_buffer(buf, cfg, csum_bytenr,
                                       BTRFS_CSUM_TREE_OBJECTID);
        if (ret < 0)
                goto out;
        /*
         * Temporary csum tree is completely empty.
         */
        ret = write_temp_extent_buffer(fd, buf, csum_bytenr);
out:
        free(buf);
        return ret;
}

/*
 * Improved version of make_btrfs().
 *
 * This one will
 * 1) Do chunk allocation to avoid used data
 *    And after this function, extent type matches chunk type
 * 2) Better structured code
 *    No super long hand written codes to initialized all tree blocks
 *    Split into small blocks and reuse codes.
 *    TODO: Reuse tree operation facilities by introducing new flags
 */
static int make_convert_btrfs(int fd, struct btrfs_mkfs_config *cfg,
                              struct btrfs_convert_context *cctx)
{
        struct cache_tree *free = &cctx->free;
        struct cache_tree *used = &cctx->used;
        u64 sys_chunk_start;
        u64 meta_chunk_start;
        /* chunk tree bytenr, in system chunk */
        u64 chunk_bytenr;
        /* metadata trees bytenr, in metadata chunk */
        u64 root_bytenr;
        u64 extent_bytenr;
        u64 dev_bytenr;
        u64 fs_bytenr;
        u64 csum_bytenr;
        int ret;

        /* Shouldn't happen */
        BUG_ON(cache_tree_empty(used));

        /*
         * reserve space for temporary superblock first
         * Here we allocate a little larger space, to keep later
         * free space will be STRIPE_LEN aligned
         */
        ret = reserve_free_space(free, BTRFS_STRIPE_LEN,
                                 &cfg->super_bytenr);
        if (ret < 0)
                goto out;

        /*
         * Then reserve system chunk space
         * TODO: Change system group size depending on cctx->total_bytes.
         * If using current 4M, it can only handle less than one TB for
         * worst case and then run out of sys space.
         */
        ret = reserve_free_space(free, BTRFS_MKFS_SYSTEM_GROUP_SIZE,
                                 &sys_chunk_start);
        if (ret < 0)
                goto out;
        ret = reserve_free_space(free, BTRFS_CONVERT_META_GROUP_SIZE,
                                 &meta_chunk_start);
        if (ret < 0)
                goto out;

        /*
         * Allocated meta/sys chunks will be mapped 1:1 with device offset.
         *
         * Inside the allocated metadata chunk, the layout will be:
         *  | offset            | contents      |
         *  -------------------------------------
         *  | +0                | tree root     |
         *  | +nodesize         | extent root   |
         *  | +nodesize * 2     | device root   |
         *  | +nodesize * 3     | fs tree       |
         *  | +nodesize * 4     | csum tree     |
         *  -------------------------------------
         * Inside the allocated system chunk, the layout will be:
         *  | offset            | contents      |
         *  -------------------------------------
         *  | +0                | chunk root    |
         *  -------------------------------------
         */
        chunk_bytenr = sys_chunk_start;
        root_bytenr = meta_chunk_start;
        extent_bytenr = meta_chunk_start + cfg->nodesize;
        dev_bytenr = meta_chunk_start + cfg->nodesize * 2;
        fs_bytenr = meta_chunk_start + cfg->nodesize * 3;
        csum_bytenr = meta_chunk_start + cfg->nodesize * 4;

        ret = setup_temp_super(fd, cfg, root_bytenr, chunk_bytenr);
        if (ret < 0)
                goto out;

        ret = setup_temp_root_tree(fd, cfg, root_bytenr, extent_bytenr,
                                   dev_bytenr, fs_bytenr, csum_bytenr);
        if (ret < 0)
                goto out;
        ret = setup_temp_chunk_tree(fd, cfg, sys_chunk_start, meta_chunk_start,
                                    chunk_bytenr);
        if (ret < 0)
                goto out;
        ret = setup_temp_dev_tree(fd, cfg, sys_chunk_start, meta_chunk_start,
                                  dev_bytenr);
        if (ret < 0)
                goto out;
        ret = setup_temp_fs_tree(fd, cfg, fs_bytenr);
        if (ret < 0)
                goto out;
        ret = setup_temp_csum_tree(fd, cfg, csum_bytenr);

out:
        return ret;
}

/*
 * @fs_uuid - if NULL, generates a UUID, returns back the new filesystem UUID
 */
int make_btrfs(int fd, struct btrfs_mkfs_config *cfg,
                struct btrfs_convert_context *cctx)
{
        struct btrfs_super_block super;
        struct extent_buffer *buf;
        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 = !!(cfg->features &
                                 BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA);
        u64 num_bytes;

        if (cctx)
                return make_convert_btrfs(fd, cfg, cctx);
        buf = malloc(sizeof(*buf) + max(cfg->sectorsize, cfg->nodesize));
        if (!buf)
                return -ENOMEM;

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

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

        num_bytes = (cfg->num_bytes / cfg->sectorsize) * cfg->sectorsize;
        if (cfg->fs_uuid && *cfg->fs_uuid) {
                if (uuid_parse(cfg->fs_uuid, super.fsid) != 0) {
                        error("cannot not parse UUID: %s", cfg->fs_uuid);
                        ret = -EINVAL;
                        goto out;
                }
                if (!test_uuid_unique(cfg->fs_uuid)) {
                        error("non-unique UUID: %s", cfg->fs_uuid);
                        ret = -EBUSY;
                        goto out;
                }
        } else {
                uuid_generate(super.fsid);
                if (cfg->fs_uuid)
                        uuid_unparse(super.fsid, cfg->fs_uuid);
        }
        uuid_generate(super.dev_item.uuid);
        uuid_generate(chunk_tree_uuid);

        btrfs_set_super_bytenr(&super, cfg->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, cfg->blocks[1]);
        btrfs_set_super_chunk_root(&super, cfg->blocks[3]);
        btrfs_set_super_total_bytes(&super, num_bytes);
        btrfs_set_super_bytes_used(&super, 6 * cfg->nodesize);
        btrfs_set_super_sectorsize(&super, cfg->sectorsize);
        btrfs_set_super_leafsize(&super, cfg->nodesize);
        btrfs_set_super_nodesize(&super, cfg->nodesize);
        btrfs_set_super_stripesize(&super, cfg->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, cfg->features);
        if (cfg->label)
                __strncpy_null(super.label, cfg->label, BTRFS_LABEL_SIZE - 1);

        /* create the tree of root objects */
        memset(buf->data, 0, cfg->nodesize);
        buf->len = cfg->nodesize;
        btrfs_set_header_bytenr(buf, cfg->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, cfg->nodesize);
        btrfs_set_stack_inode_mode(inode_item, S_IFDIR | 0755);
        btrfs_set_root_refs(&root_item, 1);
        btrfs_set_root_used(&root_item, cfg->nodesize);
        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(cfg->nodesize) - sizeof(root_item);
        btrfs_set_root_bytenr(&root_item, cfg->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, cfg->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, cfg->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, cfg->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, cfg->nodesize, cfg->blocks[1]);
        if (ret != cfg->nodesize) {
                ret = (ret < 0 ? -errno : -EIO);
                goto out;
        }

        /* create the items for the extent tree */
        memset(buf->data + sizeof(struct btrfs_header), 0,
                cfg->nodesize - sizeof(struct btrfs_header));
        nritems = 0;
        itemoff = __BTRFS_LEAF_DATA_SIZE(cfg->nodesize);
        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(cfg->blocks[i] < first_free);
                BUG_ON(cfg->blocks[i] < cfg->blocks[i - 1]);

                /* create extent item */
                itemoff -= item_size;
                btrfs_set_disk_key_objectid(&disk_key, cfg->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, cfg->nodesize);
                }
                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, cfg->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, cfg->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, cfg->nodesize, cfg->blocks[2]);
        if (ret != cfg->nodesize) {
                ret = (ret < 0 ? -errno : -EIO);
                goto out;
        }

        /* create the chunk tree */
        memset(buf->data + sizeof(struct btrfs_header), 0,
                cfg->nodesize - sizeof(struct btrfs_header));
        nritems = 0;
        item_size = sizeof(*dev_item);
        itemoff = __BTRFS_LEAF_DATA_SIZE(cfg->nodesize) - 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, cfg->sectorsize);
        btrfs_set_device_io_width(buf, dev_item, cfg->sectorsize);
        btrfs_set_device_sector_size(buf, dev_item, cfg->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, cfg->sectorsize);
        btrfs_set_chunk_io_width(buf, chunk, cfg->sectorsize);
        btrfs_set_chunk_sector_size(buf, chunk, cfg->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, cfg->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, cfg->nodesize, cfg->blocks[3]);
        if (ret != cfg->nodesize) {
                ret = (ret < 0 ? -errno : -EIO);
                goto out;
        }

        /* create the device tree */
        memset(buf->data + sizeof(struct btrfs_header), 0,
                cfg->nodesize - sizeof(struct btrfs_header));
        nritems = 0;
        itemoff = __BTRFS_LEAF_DATA_SIZE(cfg->nodesize) -
                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, cfg->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, cfg->nodesize, cfg->blocks[4]);
        if (ret != cfg->nodesize) {
                ret = (ret < 0 ? -errno : -EIO);
                goto out;
        }

        /* create the FS root */
        memset(buf->data + sizeof(struct btrfs_header), 0,
                cfg->nodesize - sizeof(struct btrfs_header));
        btrfs_set_header_bytenr(buf, cfg->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, cfg->nodesize, cfg->blocks[5]);
        if (ret != cfg->nodesize) {
                ret = (ret < 0 ? -errno : -EIO);
                goto out;
        }
        /* finally create the csum root */
        memset(buf->data + sizeof(struct btrfs_header), 0,
                cfg->nodesize - sizeof(struct btrfs_header));
        btrfs_set_header_bytenr(buf, cfg->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, cfg->nodesize, cfg->blocks[6]);
        if (ret != cfg->nodesize) {
                ret = (ret < 0 ? -errno : -EIO);
                goto out;
        }

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

        ret = 0;

out:
        free(buf);
        return ret;
}

static const struct btrfs_fs_feature {
        const char *name;
        u64 flag;
        const char *desc;
} mkfs_features[] = {
        { "mixed-bg", BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS,
                "mixed data and metadata block groups" },
        { "extref", BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF,
                "increased hardlink limit per file to 65536" },
        { "raid56", BTRFS_FEATURE_INCOMPAT_RAID56,
                "raid56 extended format" },
        { "skinny-metadata", BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA,
                "reduced-size metadata extent refs" },
        { "no-holes", BTRFS_FEATURE_INCOMPAT_NO_HOLES,
                "no explicit hole extents for files" },
        /* Keep this one last */
        { "list-all", BTRFS_FEATURE_LIST_ALL, NULL }
};

static int parse_one_fs_feature(const char *name, u64 *flags)
{
        int i;
        int found = 0;

        for (i = 0; i < ARRAY_SIZE(mkfs_features); i++) {
                if (name[0] == '^' &&
                        !strcmp(mkfs_features[i].name, name + 1)) {
                        *flags &= ~ mkfs_features[i].flag;
                        found = 1;
                } else if (!strcmp(mkfs_features[i].name, name)) {
                        *flags |= mkfs_features[i].flag;
                        found = 1;
                }
        }

        return !found;
}

void btrfs_parse_features_to_string(char *buf, u64 flags)
{
        int i;

        buf[0] = 0;

        for (i = 0; i < ARRAY_SIZE(mkfs_features); i++) {
                if (flags & mkfs_features[i].flag) {
                        if (*buf)
                                strcat(buf, ", ");
                        strcat(buf, mkfs_features[i].name);
                }
        }
}

void btrfs_process_fs_features(u64 flags)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(mkfs_features); i++) {
                if (flags & mkfs_features[i].flag) {
                        printf("Turning ON incompat feature '%s': %s\n",
                                mkfs_features[i].name,
                                mkfs_features[i].desc);
                }
        }
}

void btrfs_list_all_fs_features(u64 mask_disallowed)
{
        int i;

        fprintf(stderr, "Filesystem features available:\n");
        for (i = 0; i < ARRAY_SIZE(mkfs_features) - 1; i++) {
                char *is_default = "";

                if (mkfs_features[i].flag & mask_disallowed)
                        continue;
                if (mkfs_features[i].flag & BTRFS_MKFS_DEFAULT_FEATURES)
                        is_default = ", default";
                fprintf(stderr, "%-20s- %s (0x%llx%s)\n",
                                mkfs_features[i].name,
                                mkfs_features[i].desc,
                                mkfs_features[i].flag,
                                is_default);
        }
}

/*
 * Return NULL if all features were parsed fine, otherwise return the name of
 * the first unparsed.
 */
char* btrfs_parse_fs_features(char *namelist, u64 *flags)
{
        char *this_char;
        char *save_ptr = NULL; /* Satisfy static checkers */

        for (this_char = strtok_r(namelist, ",", &save_ptr);
             this_char != NULL;
             this_char = strtok_r(NULL, ",", &save_ptr)) {
                if (parse_one_fs_feature(this_char, flags))
                        return this_char;
        }

        return NULL;
}

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 device_total_bytes, 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 = NULL;
        u64 fs_total_bytes;
        u64 num_devs;
        int ret;

        device_total_bytes = (device_total_bytes / sectorsize) * sectorsize;

        device = kzalloc(sizeof(*device), GFP_NOFS);
        if (!device)
                goto err_nomem;
        buf = kzalloc(sectorsize, GFP_NOFS);
        if (!buf)
                goto err_nomem;
        BUG_ON(sizeof(*disk_super) > 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 = device_total_bytes;
        device->bytes_used = 0;
        device->total_ios = 0;
        device->dev_root = root->fs_info->dev_root;
        device->name = strdup(path);
        if (!device->name)
                goto err_nomem;

        INIT_LIST_HEAD(&device->dev_list);
        ret = btrfs_add_device(trans, root, device);
        BUG_ON(ret);

        fs_total_bytes = btrfs_super_total_bytes(super) + device_total_bytes;
        btrfs_set_super_total_bytes(super, fs_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));

        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;

err_nomem:
        kfree(device);
        kfree(buf);
        return -ENOMEM;
}

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

        pr = blkid_new_probe();
        if (!pr)
                return -1;

        if (blkid_probe_set_device(pr, fd, 0, 0)) {
                ret = -1;
                goto out;
        }

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

        if (ret || len == 0 || off == NULL) {
                /*
                 * If lookup fails, the probe did not find any values, eg. for
                 * a file image or a loop device. Soft error.
                 */
                ret = 1;
                goto out;
        }

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

        memset(buf, 0, len);
        ret = pwrite(fd, buf, len, offset);
        if (ret < 0) {
                error("cannot wipe existing superblock: %s", strerror(errno));
                ret = -1;
        } else if (ret != len) {
                error("cannot wipe existing superblock: wrote %d of %zd", ret, len);
                ret = -1;
        }
        fsync(fd);

out:
        blkid_free_probe(pr);
        return ret;
}

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

        ret = fstat(fd, &st);
        if (ret < 0) {
                error("unable to stat %s: %s", file, strerror(errno));
                return 1;
        }

        block_count = btrfs_device_size(fd, &st);
        if (block_count == 0) {
                error("unable to determine size of %s", file);
                return 1;
        }
        if (max_block_count)
                block_count = min(block_count, max_block_count);

        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) {
                        printf("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) {
                error("failed to zero device '%s': %s", file, strerror(-ret));
                return 1;
        }

        ret = btrfs_wipe_existing_sb(fd);
        if (ret < 0) {
                error("cannot wipe superblocks on %s", file);
                return 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;
        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->nodesize);
        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;
}

static int is_reg_file(const char *path)
{
        struct stat statbuf;

        if (stat(path, &statbuf) < 0)
                return -errno;
        return S_ISREG(statbuf.st_mode);
}

/*
 * This function checks if the given input parameter is
 * an uuid or a path
 * return <0 : some error in the given input
 * return BTRFS_ARG_UNKNOWN:    unknown input
 * return BTRFS_ARG_UUID:       given input is uuid
 * return BTRFS_ARG_MNTPOINT:   given input is path
 * return BTRFS_ARG_REG:        given input is regular file
 * return BTRFS_ARG_BLKDEV:     given input is block device
 */
int check_arg_type(const char *input)
{
        uuid_t uuid;
        char path[PATH_MAX];

        if (!input)
                return -EINVAL;

        if (realpath(input, path)) {
                if (is_block_device(path) == 1)
                        return BTRFS_ARG_BLKDEV;

                if (is_mount_point(path) == 1)
                        return BTRFS_ARG_MNTPOINT;

                if (is_reg_file(path))
                        return BTRFS_ARG_REG;

                return BTRFS_ARG_UNKNOWN;
        }

        if (strlen(input) == (BTRFS_UUID_UNPARSED_SIZE - 1) &&
                !uuid_parse(input, uuid))
                return BTRFS_ARG_UUID;

        return BTRFS_ARG_UNKNOWN;
}

/*
 * 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) {
                        error("not a block device: %s", dev);
                        ret = -EINVAL;
                } else {
                        error("cannot check %s: %s", dev, strerror(-ret));
                }
                goto out;
        }

        fd = open(dev, O_RDONLY);
        if (fd < 0) {
                ret = -errno;
                error("cannot open %s: %s", 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, int verbose)
{
        char mp[PATH_MAX];
        int ret;

        if (is_block_device(path)) {
                ret = get_btrfs_mount(path, mp, sizeof(mp));
                if (ret < 0) {
                        /* not a mounted btrfs dev */
                        error_on(verbose, "'%s' is not a mounted btrfs device",
                                 path);
                        errno = EINVAL;
                        return -1;
                }
                ret = open_file_or_dir(mp, dirstream);
                error_on(verbose && ret < 0, "can't access '%s': %s",
                         path, strerror(errno));
        } else {
                ret = btrfs_open_dir(path, dirstream, 1);
        }

        return ret;
}

/*
 * Do the following checks before calling open_file_or_dir():
 * 1: path is in a btrfs filesystem
 * 2: path is a directory
 */
int btrfs_open_dir(const char *path, DIR **dirstream, int verbose)
{
        struct statfs stfs;
        struct stat st;
        int ret;

        if (statfs(path, &stfs) != 0) {
                error_on(verbose, "cannot access '%s': %s", path,
                                strerror(errno));
                return -1;
        }

        if (stfs.f_type != BTRFS_SUPER_MAGIC) {
                error_on(verbose, "not a btrfs filesystem: %s", path);
                return -2;
        }

        if (stat(path, &st) != 0) {
                error_on(verbose, "cannot access '%s': %s", path,
                                strerror(errno));
                return -1;
        }

        if (!S_ISDIR(st.st_mode)) {
                error_on(verbose, "not a directory: %s", path);
                return -3;
        }

        ret = open_file_or_dir(path, dirstream);
        if (ret < 0) {
                error_on(verbose, "cannot access '%s': %s", path,
                                strerror(errno));
        }

        return ret;
}

/* 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) using
 * loopdev API
 */
static int resolve_loop_device_with_loopdev(const char* loop_dev, char* loop_file)
{
        int fd;
        int ret;
        struct loop_info64 lo64;

        fd = open(loop_dev, O_RDONLY | O_NONBLOCK);
        if (fd < 0)
                return -errno;
        ret = ioctl(fd, LOOP_GET_STATUS64, &lo64);
        if (ret < 0) {
                ret = -errno;
                goto out;
        }

        memcpy(loop_file, lo64.lo_file_name, sizeof(lo64.lo_file_name));
        loop_file[sizeof(lo64.lo_file_name)] = 0;

out:
        close(fd);

        return ret;
}

/* 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"))) {
                if (errno == ENOENT)
                        /*
                         * It's possibly a partitioned loop device, which is
                         * resolvable with loopdev API.
                         */
                        return resolve_loop_device_with_loopdev(loop_dev, loop_file);
                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))
                strncpy_null(real_a, a);

        if (!realpath(b, real_b))
                strncpy_null(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) {
                error("mount check: cannot open %s: %s", file,
                                strerror(errno));
                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 mounted 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;

        fd = open("/dev/btrfs-control", O_RDWR);
        if (fd < 0) {
                warning(
        "failed to open /dev/btrfs-control, skipping device registration: %s",
                        strerror(errno));
                return -errno;
        }
        memset(&args, 0, sizeof(args));
        strncpy_null(args.name, fname);
        ret = ioctl(fd, BTRFS_IOC_SCAN_DEV, &args);
        if (ret < 0) {
                error("device scan failed on '%s': %s", fname,
                                strerror(errno));
                ret = -errno;
        }
        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 = 0;
        int ret = 0;
        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 (*device->name)
                                err = btrfs_register_one_device(device->name);

                        if (err)
                                ret++;
                }
        }

        return ret;
}

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;
}

/*
 * Note: this function uses a static per-thread buffer. Do not call this
 * function more than 10 times within one argument list!
 */
const char *pretty_size_mode(u64 size, unsigned mode)
{
        static __thread int ps_index = 0;
        static __thread char ps_array[10][32];
        char *ret;

        ret = ps_array[ps_index];
        ps_index++;
        ps_index %= 10;
        (void)pretty_size_snprintf(size, ret, 32, mode);

        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 the value is smaller than base, we didn't do any
                 * division, in that case, base should be 1, not original
                 * base, or the unit will be wrong
                 */
                if (num_divs == 0)
                        base = 1;
        }

        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) {
                error("label %s is too long (max %d)", 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) {
               error("checking mount status of %s failed: %d", dev, ret);
               return -1;
        }
        if (ret > 0) {
                error("device %s is mounted, use mount point", 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);
        __strncpy_null(root->fs_info->super_copy->label, label, BTRFS_LABEL_SIZE - 1);

        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 *labelp)
{
        int fd;
        char label[BTRFS_LABEL_SIZE];

        fd = open(mount_path, O_RDONLY | O_NOATIME);
        if (fd < 0) {
                error("unable to access %s: %s", mount_path, strerror(errno));
                return -1;
        }

        memset(label, 0, sizeof(label));
        __strncpy_null(label, labelp, BTRFS_LABEL_SIZE - 1);
        if (ioctl(fd, BTRFS_IOC_SET_FSLABEL, label) < 0) {
                error("unable to set label of %s: %s", mount_path,
                                strerror(errno));
                close(fd);
                return -1;
        }

        close(fd);
        return 0;
}

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

        ret = check_mounted(dev);
        if (ret < 0) {
               error("checking mount status of %s failed: %d", dev, ret);
               return -1;
        }

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

        __strncpy_null(label, root->fs_info->super_copy->label,
                        BTRFS_LABEL_SIZE - 1);

        /* 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;
        int ret;

        fd = open(mount_path, O_RDONLY | O_NOATIME);
        if (fd < 0) {
                error("unable to access %s: %s", mount_path, strerror(errno));
                return -1;
        }

        memset(label, '\0', sizeof(label));
        ret = ioctl(fd, BTRFS_IOC_GET_FSLABEL, label);
        if (ret < 0) {
                if (errno != ENOTTY)
                        error("unable to get label of %s: %s", mount_path,
                                        strerror(errno));
                ret = -errno;
                close(fd);
                return ret;
        }

        __strncpy_null(labelp, label, BTRFS_LABEL_SIZE - 1);
        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;
}

/*
 * 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) {
                error("size value is empty");
                exit(1);
        }
        if (s[0] == '-') {
                error("size value '%s' is less equal than 0", s);
                exit(1);
        }
        ret = strtoull(s, &endptr, 10);
        if (endptr == s) {
                error("size value '%s' is invalid", s);
                exit(1);
        }
        if (endptr[0] && endptr[1]) {
                error("illegal suffix contains character '%c' in wrong position",
                        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) {
                error("size value '%s' is too large for u64", 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:
                        error("unknown size descriptor '%c'", c);
                        exit(1);
                }
        }
        /* Check whether ret * mult overflow */
        if (fls64(ret) + fls64(mult) - 1 > 64) {
                error("size value '%s' is too large for u64", s);
                exit(1);
        }
        ret *= mult;
        return ret;
}

u64 parse_qgroupid(const char *p)
{
        char *s = strchr(p, '/');
        const char *ptr_src_end = p + strlen(p);
        char *ptr_parse_end = NULL;
        u64 level;
        u64 id;
        int fd;
        int ret = 0;

        if (p[0] == '/')
                goto path;

        /* Numeric format like '0/257' is the primary case */
        if (!s) {
                id = strtoull(p, &ptr_parse_end, 10);
                if (ptr_parse_end != ptr_src_end)
                        goto path;
                return id;
        }
        level = strtoull(p, &ptr_parse_end, 10);
        if (ptr_parse_end != s)
                goto path;

        id = strtoull(s + 1, &ptr_parse_end, 10);
        if (ptr_parse_end != ptr_src_end)
                goto  path;

        return (level << BTRFS_QGROUP_LEVEL_SHIFT) | id;

path:
        /* Path format like subv at 'my_subvol' is the fallback case */
        ret = test_issubvolume(p);
        if (ret < 0 || !ret)
                goto err;
        fd = open(p, O_RDONLY);
        if (fd < 0)
                goto err;
        ret = lookup_ino_rootid(fd, &id);
        close(fd);
        if (ret < 0)
                goto err;
        return id;

err:
        error("invalid qgroupid or subvolume path: %s", p);
        exit(-1);
}

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);
                        *dirstream = NULL;
                }
        }
        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 < 0 ? -errno : 0;
}

static u64 find_max_device_id(struct btrfs_ioctl_search_args *search_args,
                              int nr_items)
{
        struct btrfs_dev_item *dev_item;
        char *buf = search_args->buf;

        buf += (nr_items - 1) * (sizeof(struct btrfs_ioctl_search_header)
                                       + sizeof(struct btrfs_dev_item));
        buf += sizeof(struct btrfs_ioctl_search_header);

        dev_item = (struct btrfs_dev_item *)buf;

        return btrfs_stack_device_id(dev_item);
}

static int search_chunk_tree_for_fs_info(int fd,
                                struct btrfs_ioctl_fs_info_args *fi_args)
{
        int ret;
        int max_items;
        u64 start_devid = 1;
        struct btrfs_ioctl_search_args search_args;
        struct btrfs_ioctl_search_key *search_key = &search_args.key;

        fi_args->num_devices = 0;

        max_items = BTRFS_SEARCH_ARGS_BUFSIZE
               / (sizeof(struct btrfs_ioctl_search_header)
                               + sizeof(struct btrfs_dev_item));

        search_key->tree_id = BTRFS_CHUNK_TREE_OBJECTID;
        search_key->min_objectid = BTRFS_DEV_ITEMS_OBJECTID;
        search_key->max_objectid = BTRFS_DEV_ITEMS_OBJECTID;
        search_key->min_type = BTRFS_DEV_ITEM_KEY;
        search_key->max_type = BTRFS_DEV_ITEM_KEY;
        search_key->min_transid = 0;
        search_key->max_transid = (u64)-1;
        search_key->nr_items = max_items;
        search_key->max_offset = (u64)-1;

again:
        search_key->min_offset = start_devid;

        ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &search_args);
        if (ret < 0)
                return -errno;

        fi_args->num_devices += (u64)search_key->nr_items;

        if (search_key->nr_items == max_items) {
                start_devid = find_max_device_id(&search_args,
                                        search_key->nr_items) + 1;
                goto again;
        }

        /* get the lastest max_id to stay consistent with the num_devices */
        if (search_key->nr_items == 0)
                /*
                 * last tree_search returns an empty buf, use the devid of
                 * the last dev_item of the previous tree_search
                 */
                fi_args->max_id = start_devid - 1;
        else
                fi_args->max_id = find_max_device_id(&search_args,
                                                search_key->nr_items);

        return 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;
        int replacing = 0;
        struct btrfs_fs_devices *fs_devices_mnt = NULL;
        struct btrfs_ioctl_dev_info_args *di_args;
        struct btrfs_ioctl_dev_info_args tmp;
        char mp[PATH_MAX];
        DIR *dirstream = NULL;

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

        if (is_block_device(path) == 1) {
                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;
                        error("cannot open %s: %s", 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;
                }

                /*
                 * The fs_args->num_devices does not include seed devices
                 */
                ret = search_chunk_tree_for_fs_info(fd, fi_args);
                if (ret)
                        goto out;

                /*
                 * search_chunk_tree_for_fs_info() will lacks the devid 0
                 * so manual probe for it here.
                 */
                ret = get_device_info(fd, 0, &tmp);
                if (!ret) {
                        fi_args->num_devices++;
                        ndevs++;
                        replacing = 1;
                        if (i == 0)
                                i++;
                }
        }

        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;
        }

        if (replacing)
                memcpy(di_args, &tmp, sizeof(tmp));
        for (; i <= fi_args->max_id; ++i) {
                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(const 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, int ssd)
{
        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;
        case 1:
                allowed |= BTRFS_BLOCK_GROUP_DUP;
        }

        if (dev_cnt > 1 &&
            ((metadata_profile | data_profile) & BTRFS_BLOCK_GROUP_DUP)) {
                warning("DUP is not recommended on filesystem with multiple devices");
        }
        if (metadata_profile & ~allowed) {
                fprintf(stderr,
                        "ERROR: 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) {
                fprintf(stderr,
                        "ERROR: 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;
        }

        warning_on(!mixed && (data_profile & BTRFS_BLOCK_GROUP_DUP) && ssd,
                   "DUP may not actually lead to 2 copies on the device, see manual page");

        return 0;
}

int group_profile_max_safe_loss(u64 flags)
{
        switch (flags & BTRFS_BLOCK_GROUP_PROFILE_MASK) {
        case 0: /* single */
        case BTRFS_BLOCK_GROUP_DUP:
        case BTRFS_BLOCK_GROUP_RAID0:
                return 0;
        case BTRFS_BLOCK_GROUP_RAID1:
        case BTRFS_BLOCK_GROUP_RAID5:
        case BTRFS_BLOCK_GROUP_RAID10:
                return 1;
        case BTRFS_BLOCK_GROUP_RAID6:
                return 2;
        default:
                return -1;
        }
}

/*
 * Check if a device is suitable for btrfs
 * returns:
 *  1: something is wrong, an error is printed
 *  0: all is fine
 */
int test_dev_for_mkfs(const char *file, int force_overwrite)
{
        int ret, fd;
        struct stat st;

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

int btrfs_scan_lblkid(void)
{
        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, NULL) < 0) {
                error("blkid cache get failed");
                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_null(path, blkid_dev_devname(dev));

                fd = open(path, O_RDONLY);
                if (fd < 0) {
                        error("cannot open %s: %s", path, strerror(errno));
                        continue;
                }
                ret = btrfs_scan_one_device(fd, path, &tmp_devices,
                                &num_devices, BTRFS_SUPER_INFO_OFFSET, 0);
                if (ret) {
                        error("cannot scan %s: %s", path, strerror(-ret));
                        close (fd);
                        continue;
                }

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

        btrfs_scan_done = 1;

        return 0;
}

int is_vol_small(const 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(const 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;

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

        ret = ioctl(fd, BTRFS_IOC_INO_LOOKUP, &args);
        if (ret < 0) {
                error("failed to lookup root id: %s", strerror(errno));
                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 nodesize)
{
        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(nodesize)) {
                close(fd);
                return 1;
        }
        close(fd);
        return 0;
}


/*
 * Test if path is a directory
 * Returns:
 *   0 - path exists but it is not a directory
 *   1 - path exists and it is a directory
 * < 0 - error
 */
int test_isdir(const char *path)
{
        struct stat st;
        int ret;

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

        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;
}

const 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";
        }
}

const 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(const char *path)
{
        struct statfs sfs;

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

u64 get_partition_size(const 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;
}

int btrfs_tree_search2_ioctl_supported(int fd)
{
        struct btrfs_ioctl_search_args_v2 *args2;
        struct btrfs_ioctl_search_key *sk;
        int args2_size = 1024;
        char args2_buf[args2_size];
        int ret;
        static int v2_supported = -1;

        if (v2_supported != -1)
                return v2_supported;

        args2 = (struct btrfs_ioctl_search_args_v2 *)args2_buf;
        sk = &(args2->key);

        /*
         * Search for the extent tree item in the root tree.
         */
        sk->tree_id = BTRFS_ROOT_TREE_OBJECTID;
        sk->min_objectid = BTRFS_EXTENT_TREE_OBJECTID;
        sk->max_objectid = BTRFS_EXTENT_TREE_OBJECTID;
        sk->min_type = BTRFS_ROOT_ITEM_KEY;
        sk->max_type = BTRFS_ROOT_ITEM_KEY;
        sk->min_offset = 0;
        sk->max_offset = (u64)-1;
        sk->min_transid = 0;
        sk->max_transid = (u64)-1;
        sk->nr_items = 1;
        args2->buf_size = args2_size - sizeof(struct btrfs_ioctl_search_args_v2);
        ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH_V2, args2);
        if (ret == -EOPNOTSUPP)
                v2_supported = 0;
        else if (ret == 0)
                v2_supported = 1;
        else
                return ret;

        return v2_supported;
}

int btrfs_check_nodesize(u32 nodesize, u32 sectorsize, u64 features)
{
        if (nodesize < sectorsize) {
                error("illegal nodesize %u (smaller than %u)",
                                nodesize, sectorsize);
                return -1;
        } else if (nodesize > BTRFS_MAX_METADATA_BLOCKSIZE) {
                error("illegal nodesize %u (larger than %u)",
                        nodesize, BTRFS_MAX_METADATA_BLOCKSIZE);
                return -1;
        } else if (nodesize & (sectorsize - 1)) {
                error("illegal nodesize %u (not aligned to %u)",
                        nodesize, sectorsize);
                return -1;
        } else if (features & BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS &&
                   nodesize != sectorsize) {
                error("illegal nodesize %u (not equal to %u for mixed block group)",
                        nodesize, sectorsize);
                return -1;
        }
        return 0;
}

/*
 * Copy a path argument from SRC to DEST and check the SRC length if it's at
 * most PATH_MAX and fits into DEST. DESTLEN is supposed to be exact size of
 * the buffer.
 * The destination buffer is zero terminated.
 * Return < 0 for error, 0 otherwise.
 */
int arg_copy_path(char *dest, const char *src, int destlen)
{
        size_t len = strlen(src);

        if (len >= PATH_MAX || len >= destlen)
                return -ENAMETOOLONG;

        __strncpy_null(dest, src, destlen);

        return 0;
}

unsigned int get_unit_mode_from_arg(int *argc, char *argv[], int df_mode)
{
        unsigned int unit_mode = UNITS_DEFAULT;
        int arg_i;
        int arg_end;

        for (arg_i = 0; arg_i < *argc; arg_i++) {
                if (!strcmp(argv[arg_i], "--"))
                        break;

                if (!strcmp(argv[arg_i], "--raw")) {
                        unit_mode = UNITS_RAW;
                        argv[arg_i] = NULL;
                        continue;
                }
                if (!strcmp(argv[arg_i], "--human-readable")) {
                        unit_mode = UNITS_HUMAN_BINARY;
                        argv[arg_i] = NULL;
                        continue;
                }

                if (!strcmp(argv[arg_i], "--iec")) {
                        units_set_mode(&unit_mode, UNITS_BINARY);
                        argv[arg_i] = NULL;
                        continue;
                }
                if (!strcmp(argv[arg_i], "--si")) {
                        units_set_mode(&unit_mode, UNITS_DECIMAL);
                        argv[arg_i] = NULL;
                        continue;
                }

                if (!strcmp(argv[arg_i], "--kbytes")) {
                        units_set_base(&unit_mode, UNITS_KBYTES);
                        argv[arg_i] = NULL;
                        continue;
                }
                if (!strcmp(argv[arg_i], "--mbytes")) {
                        units_set_base(&unit_mode, UNITS_MBYTES);
                        argv[arg_i] = NULL;
                        continue;
                }
                if (!strcmp(argv[arg_i], "--gbytes")) {
                        units_set_base(&unit_mode, UNITS_GBYTES);
                        argv[arg_i] = NULL;
                        continue;
                }
                if (!strcmp(argv[arg_i], "--tbytes")) {
                        units_set_base(&unit_mode, UNITS_TBYTES);
                        argv[arg_i] = NULL;
                        continue;
                }

                if (!df_mode)
                        continue;

                if (!strcmp(argv[arg_i], "-b")) {
                        unit_mode = UNITS_RAW;
                        argv[arg_i] = NULL;
                        continue;
                }
                if (!strcmp(argv[arg_i], "-h")) {
                        unit_mode = UNITS_HUMAN_BINARY;
                        argv[arg_i] = NULL;
                        continue;
                }
                if (!strcmp(argv[arg_i], "-H")) {
                        unit_mode = UNITS_HUMAN_DECIMAL;
                        argv[arg_i] = NULL;
                        continue;
                }
                if (!strcmp(argv[arg_i], "-k")) {
                        units_set_base(&unit_mode, UNITS_KBYTES);
                        argv[arg_i] = NULL;
                        continue;
                }
                if (!strcmp(argv[arg_i], "-m")) {
                        units_set_base(&unit_mode, UNITS_MBYTES);
                        argv[arg_i] = NULL;
                        continue;
                }
                if (!strcmp(argv[arg_i], "-g")) {
                        units_set_base(&unit_mode, UNITS_GBYTES);
                        argv[arg_i] = NULL;
                        continue;
                }
                if (!strcmp(argv[arg_i], "-t")) {
                        units_set_base(&unit_mode, UNITS_TBYTES);
                        argv[arg_i] = NULL;
                        continue;
                }
        }

        for (arg_i = 0, arg_end = 0; arg_i < *argc; arg_i++) {
                if (!argv[arg_i])
                        continue;
                argv[arg_end] = argv[arg_i];
                arg_end++;
        }

        *argc = arg_end;

        return unit_mode;
}

int string_is_numerical(const char *str)
{
        if (!(*str >= '0' && *str <= '9'))
                return 0;
        while (*str >= '0' && *str <= '9')
                str++;
        if (*str != '\0')
                return 0;
        return 1;
}

/*
 * Preprocess @argv with getopt_long to reorder options and consume the "--"
 * option separator.
 * Unknown short and long options are reported, optionally the @usage is printed
 * before exit.
 */
void clean_args_no_options(int argc, char *argv[], const char * const *usagestr)
{
        static const struct option long_options[] = {
                {NULL, 0, NULL, 0}
        };

        while (1) {
                int c = getopt_long(argc, argv, "", long_options, NULL);

                if (c < 0)
                        break;

                switch (c) {
                default:
                        if (usagestr)
                                usage(usagestr);
                }
        }
}

/* Subvolume helper functions */
/*
 * 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 subvolume
 * Returns:
 *   0 - path exists but it is not a subvolume
 *   1 - path exists and it is  a subvolume
 * < 0 - error
 */
int test_issubvolume(const char *path)
{
        struct stat     st;
        struct statfs stfs;
        int             res;

        res = stat(path, &st);
        if (res < 0)
                return -errno;

        if (st.st_ino != BTRFS_FIRST_FREE_OBJECTID || !S_ISDIR(st.st_mode))
                return 0;

        res = statfs(path, &stfs);
        if (res < 0)
                return -errno;

        return (int)stfs.f_type == BTRFS_SUPER_MAGIC;
}

const char *subvol_strip_mountpoint(const char *mnt, const char *full_path)
{
        int len = strlen(mnt);
        if (!len)
                return full_path;

        if (mnt[len - 1] != '/')
                len += 1;

        return full_path + len;
}

/*
 * Returns
 * <0: Std error
 * 0: All fine
 * 1: Error; and error info printed to the terminal. Fixme.
 * 2: If the fullpath is root tree instead of subvol tree
 */
int get_subvol_info(const char *fullpath, struct root_info *get_ri)
{
        u64 sv_id;
        int ret = 1;
        int fd = -1;
        int mntfd = -1;
        char *mnt = NULL;
        const char *svpath = NULL;
        DIR *dirstream1 = NULL;
        DIR *dirstream2 = NULL;

        ret = test_issubvolume(fullpath);
        if (ret < 0)
                return ret;
        if (!ret) {
                error("not a subvolume: %s", fullpath);
                return 1;
        }

        ret = find_mount_root(fullpath, &mnt);
        if (ret < 0)
                return ret;
        if (ret > 0) {
                error("%s doesn't belong to btrfs mount point", fullpath);
                return 1;
        }
        ret = 1;
        svpath = subvol_strip_mountpoint(mnt, fullpath);

        fd = btrfs_open_dir(fullpath, &dirstream1, 1);
        if (fd < 0)
                goto out;

        ret = btrfs_list_get_path_rootid(fd, &sv_id);
        if (ret) {
                error("can't get rootid for '%s'", fullpath);
                goto out;
        }

        mntfd = btrfs_open_dir(mnt, &dirstream2, 1);
        if (mntfd < 0)
                goto out;

        if (sv_id == BTRFS_FS_TREE_OBJECTID) {
                ret = 2;
                /*
                 * So that caller may decide if thats an error or just fine.
                 */
                goto out;
        }

        memset(get_ri, 0, sizeof(*get_ri));
        get_ri->root_id = sv_id;

        ret = btrfs_get_subvol(mntfd, get_ri);
        if (ret)
                error("can't find '%s': %d", svpath, ret);

out:
        close_file_or_dir(mntfd, dirstream2);
        close_file_or_dir(fd, dirstream1);
        free(mnt);

        return ret;
}

void init_rand_seed(u64 seed)
{
        int i;

        /* only use the last 48 bits */
        for (i = 0; i < 3; i++) {
                rand_seed[i] = (unsigned short)(seed ^ (unsigned short)(-1));
                seed >>= 16;
        }
        rand_seed_initlized = 1;
}

static void __init_seed(void)
{
        struct timeval tv;
        int ret;
        int fd;

        if(rand_seed_initlized)
                return;
        /* Use urandom as primary seed source. */
        fd = open("/dev/urandom", O_RDONLY);
        if (fd >= 0) {
                ret = read(fd, rand_seed, sizeof(rand_seed));
                close(fd);
                if (ret < sizeof(rand_seed))
                        goto fallback;
        } else {
fallback:
                /* Use time and pid as fallback seed */
                warning("failed to read /dev/urandom, use time and pid as random seed");
                gettimeofday(&tv, 0);
                rand_seed[0] = getpid() ^ (tv.tv_sec & 0xFFFF);
                rand_seed[1] = getppid() ^ (tv.tv_usec & 0xFFFF);
                rand_seed[2] = (tv.tv_sec ^ tv.tv_usec) >> 16;
        }
        rand_seed_initlized = 1;
}

u32 rand_u32(void)
{
        __init_seed();
        /*
         * Don't use nrand48, its range is [0,2^31) The highest bit will alwasy
         * be 0.  Use jrand48 to include the highest bit.
         */
        return (u32)jrand48(rand_seed);
}

unsigned int rand_range(unsigned int upper)
{
        __init_seed();
        /*
         * Use the full 48bits to mod, which would be more uniformly
         * distributed
         */
        return (unsigned int)(jrand48(rand_seed) % upper);
}