source: src/router/btrfsprogs/volumes.c @ 17848

/*
 * Copyright (C) 2007 Oracle.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License v2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */
#define _XOPEN_SOURCE 600
#define __USE_XOPEN2K
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <uuid/uuid.h>
#include <fcntl.h>
#include <unistd.h>
#include "ctree.h"
#include "disk-io.h"
#include "transaction.h"
#include "print-tree.h"
#include "volumes.h"

struct stripe {
        struct btrfs_device *dev;
        u64 physical;
};

struct map_lookup {
        struct cache_extent ce;
        u64 type;
        int io_align;
        int io_width;
        int stripe_len;
        int sector_size;
        int num_stripes;
        int sub_stripes;
        struct btrfs_bio_stripe stripes[];
};

#define map_lookup_size(n) (sizeof(struct map_lookup) + \
                            (sizeof(struct btrfs_bio_stripe) * (n)))

static LIST_HEAD(fs_uuids);

static struct btrfs_device *__find_device(struct list_head *head, u64 devid,
                                          u8 *uuid)
{
        struct btrfs_device *dev;
        struct list_head *cur;

        list_for_each(cur, head) {
                dev = list_entry(cur, struct btrfs_device, dev_list);
                if (dev->devid == devid &&
                    !memcmp(dev->uuid, uuid, BTRFS_UUID_SIZE)) {
                        return dev;
                }
        }
        return NULL;
}

static struct btrfs_fs_devices *find_fsid(u8 *fsid)
{
        struct list_head *cur;
        struct btrfs_fs_devices *fs_devices;

        list_for_each(cur, &fs_uuids) {
                fs_devices = list_entry(cur, struct btrfs_fs_devices, list);
                if (memcmp(fsid, fs_devices->fsid, BTRFS_FSID_SIZE) == 0)
                        return fs_devices;
        }
        return NULL;
}

static int device_list_add(const char *path,
                           struct btrfs_super_block *disk_super,
                           u64 devid, struct btrfs_fs_devices **fs_devices_ret)
{
        struct btrfs_device *device;
        struct btrfs_fs_devices *fs_devices;
        u64 found_transid = btrfs_super_generation(disk_super);

        fs_devices = find_fsid(disk_super->fsid);
        if (!fs_devices) {
                fs_devices = kzalloc(sizeof(*fs_devices), GFP_NOFS);
                if (!fs_devices)
                        return -ENOMEM;
                INIT_LIST_HEAD(&fs_devices->devices);
                list_add(&fs_devices->list, &fs_uuids);
                memcpy(fs_devices->fsid, disk_super->fsid, BTRFS_FSID_SIZE);
                fs_devices->latest_devid = devid;
                fs_devices->latest_trans = found_transid;
                fs_devices->lowest_devid = (u64)-1;
                device = NULL;
        } else {
                device = __find_device(&fs_devices->devices, devid,
                                       disk_super->dev_item.uuid);
        }
        if (!device) {
                device = kzalloc(sizeof(*device), GFP_NOFS);
                if (!device) {
                        /* we can safely leave the fs_devices entry around */
                        return -ENOMEM;
                }
                device->devid = devid;
                memcpy(device->uuid, disk_super->dev_item.uuid,
                       BTRFS_UUID_SIZE);
                device->name = kstrdup(path, GFP_NOFS);
                if (!device->name) {
                        kfree(device);
                        return -ENOMEM;
                }
                device->label = kstrdup(disk_super->label, GFP_NOFS);
                device->total_devs = btrfs_super_num_devices(disk_super);
                device->super_bytes_used = btrfs_super_bytes_used(disk_super);
                device->total_bytes =
                        btrfs_stack_device_total_bytes(&disk_super->dev_item);
                device->bytes_used =
                        btrfs_stack_device_bytes_used(&disk_super->dev_item);
                list_add(&device->dev_list, &fs_devices->devices);
                device->fs_devices = fs_devices;
        }

        if (found_transid > fs_devices->latest_trans) {
                fs_devices->latest_devid = devid;
                fs_devices->latest_trans = found_transid;
        }
        if (fs_devices->lowest_devid > devid) {
                fs_devices->lowest_devid = devid;
        }
        *fs_devices_ret = fs_devices;
        return 0;
}

int btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
{
        struct btrfs_fs_devices *seed_devices;
        struct list_head *cur;
        struct btrfs_device *device;
again:
        list_for_each(cur, &fs_devices->devices) {
                device = list_entry(cur, struct btrfs_device, dev_list);
                close(device->fd);
                device->fd = -1;
                device->writeable = 0;
        }

        seed_devices = fs_devices->seed;
        fs_devices->seed = NULL;
        if (seed_devices) {
                fs_devices = seed_devices;
                goto again;
        }

        return 0;
}

int btrfs_open_devices(struct btrfs_fs_devices *fs_devices, int flags)
{
        int fd;
        struct list_head *head = &fs_devices->devices;
        struct list_head *cur;
        struct btrfs_device *device;
        int ret;

        list_for_each(cur, head) {
                device = list_entry(cur, struct btrfs_device, dev_list);

                fd = open(device->name, flags);
                if (fd < 0) {
                        ret = -errno;
                        goto fail;
                }

                if (device->devid == fs_devices->latest_devid)
                        fs_devices->latest_bdev = fd;
                if (device->devid == fs_devices->lowest_devid)
                        fs_devices->lowest_bdev = fd;
                device->fd = fd;
                if (flags == O_RDWR)
                        device->writeable = 1;
        }
        return 0;
fail:
        btrfs_close_devices(fs_devices);
        return ret;
}

int btrfs_scan_one_device(int fd, const char *path,
                          struct btrfs_fs_devices **fs_devices_ret,
                          u64 *total_devs, u64 super_offset)
{
        struct btrfs_super_block *disk_super;
        char *buf;
        int ret;
        u64 devid;
        char uuidbuf[37];

        buf = malloc(4096);
        if (!buf) {
                ret = -ENOMEM;
                goto error;
        }
        disk_super = (struct btrfs_super_block *)buf;
        ret = btrfs_read_dev_super(fd, disk_super, super_offset);
        if (ret < 0) {
                ret = -EIO;
                goto error_brelse;
        }
        devid = le64_to_cpu(disk_super->dev_item.devid);
        if (btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_METADUMP)
                *total_devs = 1;
        else
                *total_devs = btrfs_super_num_devices(disk_super);
        uuid_unparse(disk_super->fsid, uuidbuf);

        ret = device_list_add(path, disk_super, devid, fs_devices_ret);

error_brelse:
        free(buf);
error:
        return ret;
}

/*
 * this uses a pretty simple search, the expectation is that it is
 * called very infrequently and that a given device has a small number
 * of extents
 */
static int find_free_dev_extent(struct btrfs_trans_handle *trans,
                                struct btrfs_device *device,
                                struct btrfs_path *path,
                                u64 num_bytes, u64 *start)
{
        struct btrfs_key key;
        struct btrfs_root *root = device->dev_root;
        struct btrfs_dev_extent *dev_extent = NULL;
        u64 hole_size = 0;
        u64 last_byte = 0;
        u64 search_start = 0;
        u64 search_end = device->total_bytes;
        int ret;
        int slot = 0;
        int start_found;
        struct extent_buffer *l;

        start_found = 0;
        path->reada = 2;

        /* FIXME use last free of some kind */

        /* we don't want to overwrite the superblock on the drive,
         * so we make sure to start at an offset of at least 1MB
         */
        search_start = max((u64)1024 * 1024, search_start);

        if (root->fs_info->alloc_start + num_bytes <= device->total_bytes)
                search_start = max(root->fs_info->alloc_start, search_start);

        key.objectid = device->devid;
        key.offset = search_start;
        key.type = BTRFS_DEV_EXTENT_KEY;
        ret = btrfs_search_slot(trans, root, &key, path, 0, 0);
        if (ret < 0)
                goto error;
        ret = btrfs_previous_item(root, path, 0, key.type);
        if (ret < 0)
                goto error;
        l = path->nodes[0];
        btrfs_item_key_to_cpu(l, &key, path->slots[0]);
        while (1) {
                l = path->nodes[0];
                slot = path->slots[0];
                if (slot >= btrfs_header_nritems(l)) {
                        ret = btrfs_next_leaf(root, path);
                        if (ret == 0)
                                continue;
                        if (ret < 0)
                                goto error;
no_more_items:
                        if (!start_found) {
                                if (search_start >= search_end) {
                                        ret = -ENOSPC;
                                        goto error;
                                }
                                *start = search_start;
                                start_found = 1;
                                goto check_pending;
                        }
                        *start = last_byte > search_start ?
                                last_byte : search_start;
                        if (search_end <= *start) {
                                ret = -ENOSPC;
                                goto error;
                        }
                        goto check_pending;
                }
                btrfs_item_key_to_cpu(l, &key, slot);

                if (key.objectid < device->devid)
                        goto next;

                if (key.objectid > device->devid)
                        goto no_more_items;

                if (key.offset >= search_start && key.offset > last_byte &&
                    start_found) {
                        if (last_byte < search_start)
                                last_byte = search_start;
                        hole_size = key.offset - last_byte;
                        if (key.offset > last_byte &&
                            hole_size >= num_bytes) {
                                *start = last_byte;
                                goto check_pending;
                        }
                }
                if (btrfs_key_type(&key) != BTRFS_DEV_EXTENT_KEY) {
                        goto next;
                }

                start_found = 1;
                dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
                last_byte = key.offset + btrfs_dev_extent_length(l, dev_extent);
next:
                path->slots[0]++;
                cond_resched();
        }
check_pending:
        /* we have to make sure we didn't find an extent that has already
         * been allocated by the map tree or the original allocation
         */
        btrfs_release_path(root, path);
        BUG_ON(*start < search_start);

        if (*start + num_bytes > search_end) {
                ret = -ENOSPC;
                goto error;
        }
        /* check for pending inserts here */
        return 0;

error:
        btrfs_release_path(root, path);
        return ret;
}

int btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
                           struct btrfs_device *device,
                           u64 chunk_tree, u64 chunk_objectid,
                           u64 chunk_offset,
                           u64 num_bytes, u64 *start)
{
        int ret;
        struct btrfs_path *path;
        struct btrfs_root *root = device->dev_root;
        struct btrfs_dev_extent *extent;
        struct extent_buffer *leaf;
        struct btrfs_key key;

        path = btrfs_alloc_path();
        if (!path)
                return -ENOMEM;

        ret = find_free_dev_extent(trans, device, path, num_bytes, start);
        if (ret) {
                goto err;
        }

        key.objectid = device->devid;
        key.offset = *start;
        key.type = BTRFS_DEV_EXTENT_KEY;
        ret = btrfs_insert_empty_item(trans, root, path, &key,
                                      sizeof(*extent));
        BUG_ON(ret);

        leaf = path->nodes[0];
        extent = btrfs_item_ptr(leaf, path->slots[0],
                                struct btrfs_dev_extent);
        btrfs_set_dev_extent_chunk_tree(leaf, extent, chunk_tree);
        btrfs_set_dev_extent_chunk_objectid(leaf, extent, chunk_objectid);
        btrfs_set_dev_extent_chunk_offset(leaf, extent, chunk_offset);

        write_extent_buffer(leaf, root->fs_info->chunk_tree_uuid,
                    (unsigned long)btrfs_dev_extent_chunk_tree_uuid(extent),
                    BTRFS_UUID_SIZE);

        btrfs_set_dev_extent_length(leaf, extent, num_bytes);
        btrfs_mark_buffer_dirty(leaf);
err:
        btrfs_free_path(path);
        return ret;
}

static int find_next_chunk(struct btrfs_root *root, u64 objectid, u64 *offset)
{
        struct btrfs_path *path;
        int ret;
        struct btrfs_key key;
        struct btrfs_chunk *chunk;
        struct btrfs_key found_key;

        path = btrfs_alloc_path();
        BUG_ON(!path);

        key.objectid = objectid;
        key.offset = (u64)-1;
        key.type = BTRFS_CHUNK_ITEM_KEY;

        ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
        if (ret < 0)
                goto error;

        BUG_ON(ret == 0);

        ret = btrfs_previous_item(root, path, 0, BTRFS_CHUNK_ITEM_KEY);
        if (ret) {
                *offset = 0;
        } else {
                btrfs_item_key_to_cpu(path->nodes[0], &found_key,
                                      path->slots[0]);
                if (found_key.objectid != objectid)
                        *offset = 0;
                else {
                        chunk = btrfs_item_ptr(path->nodes[0], path->slots[0],
                                               struct btrfs_chunk);
                        *offset = found_key.offset +
                                btrfs_chunk_length(path->nodes[0], chunk);
                }
        }
        ret = 0;
error:
        btrfs_free_path(path);
        return ret;
}

static int find_next_devid(struct btrfs_root *root, struct btrfs_path *path,
                           u64 *objectid)
{
        int ret;
        struct btrfs_key key;
        struct btrfs_key found_key;

        key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
        key.type = BTRFS_DEV_ITEM_KEY;
        key.offset = (u64)-1;

        ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
        if (ret < 0)
                goto error;

        BUG_ON(ret == 0);

        ret = btrfs_previous_item(root, path, BTRFS_DEV_ITEMS_OBJECTID,
                                  BTRFS_DEV_ITEM_KEY);
        if (ret) {
                *objectid = 1;
        } else {
                btrfs_item_key_to_cpu(path->nodes[0], &found_key,
                                      path->slots[0]);
                *objectid = found_key.offset + 1;
        }
        ret = 0;
error:
        btrfs_release_path(root, path);
        return ret;
}

/*
 * the device information is stored in the chunk root
 * the btrfs_device struct should be fully filled in
 */
int btrfs_add_device(struct btrfs_trans_handle *trans,
                     struct btrfs_root *root,
                     struct btrfs_device *device)
{
        int ret;
        struct btrfs_path *path;
        struct btrfs_dev_item *dev_item;
        struct extent_buffer *leaf;
        struct btrfs_key key;
        unsigned long ptr;
        u64 free_devid = 0;

        root = root->fs_info->chunk_root;

        path = btrfs_alloc_path();
        if (!path)
                return -ENOMEM;

        ret = find_next_devid(root, path, &free_devid);
        if (ret)
                goto out;

        key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
        key.type = BTRFS_DEV_ITEM_KEY;
        key.offset = free_devid;

        ret = btrfs_insert_empty_item(trans, root, path, &key,
                                      sizeof(*dev_item));
        if (ret)
                goto out;

        leaf = path->nodes[0];
        dev_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dev_item);

        device->devid = free_devid;
        btrfs_set_device_id(leaf, dev_item, device->devid);
        btrfs_set_device_generation(leaf, dev_item, 0);
        btrfs_set_device_type(leaf, dev_item, device->type);
        btrfs_set_device_io_align(leaf, dev_item, device->io_align);
        btrfs_set_device_io_width(leaf, dev_item, device->io_width);
        btrfs_set_device_sector_size(leaf, dev_item, device->sector_size);
        btrfs_set_device_total_bytes(leaf, dev_item, device->total_bytes);
        btrfs_set_device_bytes_used(leaf, dev_item, device->bytes_used);
        btrfs_set_device_group(leaf, dev_item, 0);
        btrfs_set_device_seek_speed(leaf, dev_item, 0);
        btrfs_set_device_bandwidth(leaf, dev_item, 0);
        btrfs_set_device_start_offset(leaf, dev_item, 0);

        ptr = (unsigned long)btrfs_device_uuid(dev_item);
        write_extent_buffer(leaf, device->uuid, ptr, BTRFS_UUID_SIZE);
        ptr = (unsigned long)btrfs_device_fsid(dev_item);
        write_extent_buffer(leaf, root->fs_info->fsid, ptr, BTRFS_UUID_SIZE);
        btrfs_mark_buffer_dirty(leaf);
        ret = 0;

out:
        btrfs_free_path(path);
        return ret;
}

int btrfs_update_device(struct btrfs_trans_handle *trans,
                        struct btrfs_device *device)
{
        int ret;
        struct btrfs_path *path;
        struct btrfs_root *root;
        struct btrfs_dev_item *dev_item;
        struct extent_buffer *leaf;
        struct btrfs_key key;

        root = device->dev_root->fs_info->chunk_root;

        path = btrfs_alloc_path();
        if (!path)
                return -ENOMEM;

        key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
        key.type = BTRFS_DEV_ITEM_KEY;
        key.offset = device->devid;

        ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
        if (ret < 0)
                goto out;

        if (ret > 0) {
                ret = -ENOENT;
                goto out;
        }

        leaf = path->nodes[0];
        dev_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dev_item);

        btrfs_set_device_id(leaf, dev_item, device->devid);
        btrfs_set_device_type(leaf, dev_item, device->type);
        btrfs_set_device_io_align(leaf, dev_item, device->io_align);
        btrfs_set_device_io_width(leaf, dev_item, device->io_width);
        btrfs_set_device_sector_size(leaf, dev_item, device->sector_size);
        btrfs_set_device_total_bytes(leaf, dev_item, device->total_bytes);
        btrfs_set_device_bytes_used(leaf, dev_item, device->bytes_used);
        btrfs_mark_buffer_dirty(leaf);

out:
        btrfs_free_path(path);
        return ret;
}

int btrfs_add_system_chunk(struct btrfs_trans_handle *trans,
                           struct btrfs_root *root,
                           struct btrfs_key *key,
                           struct btrfs_chunk *chunk, int item_size)
{
        struct btrfs_super_block *super_copy = &root->fs_info->super_copy;
        struct btrfs_disk_key disk_key;
        u32 array_size;
        u8 *ptr;

        array_size = btrfs_super_sys_array_size(super_copy);
        if (array_size + item_size > BTRFS_SYSTEM_CHUNK_ARRAY_SIZE)
                return -EFBIG;

        ptr = super_copy->sys_chunk_array + array_size;
        btrfs_cpu_key_to_disk(&disk_key, key);
        memcpy(ptr, &disk_key, sizeof(disk_key));
        ptr += sizeof(disk_key);
        memcpy(ptr, chunk, item_size);
        item_size += sizeof(disk_key);
        btrfs_set_super_sys_array_size(super_copy, array_size + item_size);
        return 0;
}

static u64 div_factor(u64 num, int factor)
{
        if (factor == 10)
                return num;
        num *= factor;
        return num / 10;
}

static u64 chunk_bytes_by_type(u64 type, u64 calc_size, int num_stripes,
                               int sub_stripes)
{
        if (type & (BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_DUP))
                return calc_size;
        else if (type & BTRFS_BLOCK_GROUP_RAID10)
                return calc_size * (num_stripes / sub_stripes);
        else
                return calc_size * num_stripes;
}


int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
                      struct btrfs_root *extent_root, u64 *start,
                      u64 *num_bytes, u64 type)
{
        u64 dev_offset;
        struct btrfs_fs_info *info = extent_root->fs_info;
        struct btrfs_root *chunk_root = extent_root->fs_info->chunk_root;
        struct btrfs_stripe *stripes;
        struct btrfs_device *device = NULL;
        struct btrfs_chunk *chunk;
        struct list_head private_devs;
        struct list_head *dev_list = &extent_root->fs_info->fs_devices->devices;
        struct list_head *cur;
        struct map_lookup *map;
        int min_stripe_size = 1 * 1024 * 1024;
        u64 physical;
        u64 calc_size = 8 * 1024 * 1024;
        u64 min_free;
        u64 max_chunk_size = 4 * calc_size;
        u64 avail;
        u64 max_avail = 0;
        u64 percent_max;
        int num_stripes = 1;
        int min_stripes = 1;
        int sub_stripes = 0;
        int looped = 0;
        int ret;
        int index;
        int stripe_len = 64 * 1024;
        struct btrfs_key key;

        if (list_empty(dev_list)) {
                return -ENOSPC;
        }

        if (type & (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1 |
                    BTRFS_BLOCK_GROUP_RAID10 |
                    BTRFS_BLOCK_GROUP_DUP)) {
                if (type & BTRFS_BLOCK_GROUP_SYSTEM) {
                        calc_size = 8 * 1024 * 1024;
                        max_chunk_size = calc_size * 2;
                        min_stripe_size = 1 * 1024 * 1024;
                } else if (type & BTRFS_BLOCK_GROUP_DATA) {
                        calc_size = 1024 * 1024 * 1024;
                        max_chunk_size = 10 * calc_size;
                        min_stripe_size = 64 * 1024 * 1024;
                } else if (type & BTRFS_BLOCK_GROUP_METADATA) {
                        calc_size = 1024 * 1024 * 1024;
                        max_chunk_size = 4 * calc_size;
                        min_stripe_size = 32 * 1024 * 1024;
                }
        }
        if (type & BTRFS_BLOCK_GROUP_RAID1) {
                num_stripes = min_t(u64, 2,
                                  btrfs_super_num_devices(&info->super_copy));
                if (num_stripes < 2)
                        return -ENOSPC;
                min_stripes = 2;
        }
        if (type & BTRFS_BLOCK_GROUP_DUP) {
                num_stripes = 2;
                min_stripes = 2;
        }
        if (type & (BTRFS_BLOCK_GROUP_RAID0)) {
                num_stripes = btrfs_super_num_devices(&info->super_copy);
                min_stripes = 2;
        }
        if (type & (BTRFS_BLOCK_GROUP_RAID10)) {
                num_stripes = btrfs_super_num_devices(&info->super_copy);
                if (num_stripes < 4)
                        return -ENOSPC;
                num_stripes &= ~(u32)1;
                sub_stripes = 2;
                min_stripes = 4;
        }

        /* we don't want a chunk larger than 10% of the FS */
        percent_max = div_factor(btrfs_super_total_bytes(&info->super_copy), 1);
        max_chunk_size = min(percent_max, max_chunk_size);

again:
        if (chunk_bytes_by_type(type, calc_size, num_stripes, sub_stripes) >
            max_chunk_size) {
                calc_size = max_chunk_size;
                calc_size /= num_stripes;
                calc_size /= stripe_len;
                calc_size *= stripe_len;
        }
        /* we don't want tiny stripes */
        calc_size = max_t(u64, calc_size, min_stripe_size);

        calc_size /= stripe_len;
        calc_size *= stripe_len;
        INIT_LIST_HEAD(&private_devs);
        cur = dev_list->next;
        index = 0;

        if (type & BTRFS_BLOCK_GROUP_DUP)
                min_free = calc_size * 2;
        else
                min_free = calc_size;

        /* build a private list of devices we will allocate from */
        while(index < num_stripes) {
                device = list_entry(cur, struct btrfs_device, dev_list);
                avail = device->total_bytes - device->bytes_used;
                cur = cur->next;
                if (avail >= min_free) {
                        list_move_tail(&device->dev_list, &private_devs);
                        index++;
                        if (type & BTRFS_BLOCK_GROUP_DUP)
                                index++;
                } else if (avail > max_avail)
                        max_avail = avail;
                if (cur == dev_list)
                        break;
        }
        if (index < num_stripes) {
                list_splice(&private_devs, dev_list);
                if (index >= min_stripes) {
                        num_stripes = index;
                        if (type & (BTRFS_BLOCK_GROUP_RAID10)) {
                                num_stripes /= sub_stripes;
                                num_stripes *= sub_stripes;
                        }
                        looped = 1;
                        goto again;
                }
                if (!looped && max_avail > 0) {
                        looped = 1;
                        calc_size = max_avail;
                        goto again;
                }
                return -ENOSPC;
        }
        key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
        key.type = BTRFS_CHUNK_ITEM_KEY;
        ret = find_next_chunk(chunk_root, BTRFS_FIRST_CHUNK_TREE_OBJECTID,
                              &key.offset);
        if (ret)
                return ret;

        chunk = kmalloc(btrfs_chunk_item_size(num_stripes), GFP_NOFS);
        if (!chunk)
                return -ENOMEM;

        map = kmalloc(map_lookup_size(num_stripes), GFP_NOFS);
        if (!map) {
                kfree(chunk);
                return -ENOMEM;
        }

        stripes = &chunk->stripe;
        *num_bytes = chunk_bytes_by_type(type, calc_size,
                                         num_stripes, sub_stripes);
        index = 0;
        while(index < num_stripes) {
                struct btrfs_stripe *stripe;
                BUG_ON(list_empty(&private_devs));
                cur = private_devs.next;
                device = list_entry(cur, struct btrfs_device, dev_list);

                /* loop over this device again if we're doing a dup group */
                if (!(type & BTRFS_BLOCK_GROUP_DUP) ||
                    (index == num_stripes - 1))
                        list_move_tail(&device->dev_list, dev_list);

                ret = btrfs_alloc_dev_extent(trans, device,
                             info->chunk_root->root_key.objectid,
                             BTRFS_FIRST_CHUNK_TREE_OBJECTID, key.offset,
                             calc_size, &dev_offset);
                BUG_ON(ret);

                device->bytes_used += calc_size;
                ret = btrfs_update_device(trans, device);
                BUG_ON(ret);

                map->stripes[index].dev = device;
                map->stripes[index].physical = dev_offset;
                stripe = stripes + index;
                btrfs_set_stack_stripe_devid(stripe, device->devid);
                btrfs_set_stack_stripe_offset(stripe, dev_offset);
                memcpy(stripe->dev_uuid, device->uuid, BTRFS_UUID_SIZE);
                physical = dev_offset;
                index++;
        }
        BUG_ON(!list_empty(&private_devs));

        /* key was set above */
        btrfs_set_stack_chunk_length(chunk, *num_bytes);
        btrfs_set_stack_chunk_owner(chunk, extent_root->root_key.objectid);
        btrfs_set_stack_chunk_stripe_len(chunk, stripe_len);
        btrfs_set_stack_chunk_type(chunk, type);
        btrfs_set_stack_chunk_num_stripes(chunk, num_stripes);
        btrfs_set_stack_chunk_io_align(chunk, stripe_len);
        btrfs_set_stack_chunk_io_width(chunk, stripe_len);
        btrfs_set_stack_chunk_sector_size(chunk, extent_root->sectorsize);
        btrfs_set_stack_chunk_sub_stripes(chunk, sub_stripes);
        map->sector_size = extent_root->sectorsize;
        map->stripe_len = stripe_len;
        map->io_align = stripe_len;
        map->io_width = stripe_len;
        map->type = type;
        map->num_stripes = num_stripes;
        map->sub_stripes = sub_stripes;

        ret = btrfs_insert_item(trans, chunk_root, &key, chunk,
                                btrfs_chunk_item_size(num_stripes));
        BUG_ON(ret);
        *start = key.offset;;

        map->ce.start = key.offset;
        map->ce.size = *num_bytes;

        ret = insert_existing_cache_extent(
                           &extent_root->fs_info->mapping_tree.cache_tree,
                           &map->ce);
        BUG_ON(ret);

        if (type & BTRFS_BLOCK_GROUP_SYSTEM) {
                ret = btrfs_add_system_chunk(trans, chunk_root, &key,
                                    chunk, btrfs_chunk_item_size(num_stripes));
                BUG_ON(ret);
        }

        kfree(chunk);
        return ret;
}

void btrfs_mapping_init(struct btrfs_mapping_tree *tree)
{
        cache_tree_init(&tree->cache_tree);
}

int btrfs_num_copies(struct btrfs_mapping_tree *map_tree, u64 logical, u64 len)
{
        struct cache_extent *ce;
        struct map_lookup *map;
        int ret;
        u64 offset;

        ce = find_first_cache_extent(&map_tree->cache_tree, logical);
        BUG_ON(!ce);
        BUG_ON(ce->start > logical || ce->start + ce->size < logical);
        map = container_of(ce, struct map_lookup, ce);

        offset = logical - ce->start;
        if (map->type & (BTRFS_BLOCK_GROUP_DUP | BTRFS_BLOCK_GROUP_RAID1))
                ret = map->num_stripes;
        else if (map->type & BTRFS_BLOCK_GROUP_RAID10)
                ret = map->sub_stripes;
        else
                ret = 1;
        return ret;
}

int btrfs_rmap_block(struct btrfs_mapping_tree *map_tree,
                     u64 chunk_start, u64 physical, u64 devid,
                     u64 **logical, int *naddrs, int *stripe_len)
{
        struct cache_extent *ce;
        struct map_lookup *map;
        u64 *buf;
        u64 bytenr;
        u64 length;
        u64 stripe_nr;
        int i, j, nr = 0;

        ce = find_first_cache_extent(&map_tree->cache_tree, chunk_start);
        BUG_ON(!ce);
        map = container_of(ce, struct map_lookup, ce);

        length = ce->size;
        if (map->type & BTRFS_BLOCK_GROUP_RAID10)
                length = ce->size / (map->num_stripes / map->sub_stripes);
        else if (map->type & BTRFS_BLOCK_GROUP_RAID0)
                length = ce->size / map->num_stripes;

        buf = kzalloc(sizeof(u64) * map->num_stripes, GFP_NOFS);

        for (i = 0; i < map->num_stripes; i++) {
                if (devid && map->stripes[i].dev->devid != devid)
                        continue;
                if (map->stripes[i].physical > physical ||
                    map->stripes[i].physical + length <= physical)
                        continue;

                stripe_nr = (physical - map->stripes[i].physical) /
                            map->stripe_len;

                if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
                        stripe_nr = (stripe_nr * map->num_stripes + i) /
                                    map->sub_stripes;
                } else if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
                        stripe_nr = stripe_nr * map->num_stripes + i;
                }
                bytenr = ce->start + stripe_nr * map->stripe_len;
                for (j = 0; j < nr; j++) {
                        if (buf[j] == bytenr)
                                break;
                }
                if (j == nr)
                        buf[nr++] = bytenr;
        }

        *logical = buf;
        *naddrs = nr;
        *stripe_len = map->stripe_len;

        return 0;
}

int btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,
                    u64 logical, u64 *length,
                    struct btrfs_multi_bio **multi_ret, int mirror_num)
{
        struct cache_extent *ce;
        struct map_lookup *map;
        u64 offset;
        u64 stripe_offset;
        u64 stripe_nr;
        int stripes_allocated = 8;
        int stripes_required = 1;
        int stripe_index;
        int i;
        struct btrfs_multi_bio *multi = NULL;

        if (multi_ret && rw == READ) {
                stripes_allocated = 1;
        }
again:
        if (multi_ret) {
                multi = kzalloc(btrfs_multi_bio_size(stripes_allocated),
                                GFP_NOFS);
                if (!multi)
                        return -ENOMEM;
        }

        ce = find_first_cache_extent(&map_tree->cache_tree, logical);
        BUG_ON(!ce);
        BUG_ON(ce->start > logical || ce->start + ce->size < logical);
        map = container_of(ce, struct map_lookup, ce);
        offset = logical - ce->start;

        if (rw == WRITE) {
                if (map->type & (BTRFS_BLOCK_GROUP_RAID1 |
                                 BTRFS_BLOCK_GROUP_DUP)) {
                        stripes_required = map->num_stripes;
                } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
                        stripes_required = map->sub_stripes;
                }
        }
        /* if our multi bio struct is too small, back off and try again */
        if (multi_ret && rw == WRITE &&
            stripes_allocated < stripes_required) {
                stripes_allocated = map->num_stripes;
                kfree(multi);
                goto again;
        }
        stripe_nr = offset;
        /*
         * stripe_nr counts the total number of stripes we have to stride
         * to get to this block
         */
        stripe_nr = stripe_nr / map->stripe_len;

        stripe_offset = stripe_nr * map->stripe_len;
        BUG_ON(offset < stripe_offset);

        /* stripe_offset is the offset of this block in its stripe*/
        stripe_offset = offset - stripe_offset;

        if (map->type & (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1 |
                         BTRFS_BLOCK_GROUP_RAID10 |
                         BTRFS_BLOCK_GROUP_DUP)) {
                /* we limit the length of each bio to what fits in a stripe */
                *length = min_t(u64, ce->size - offset,
                              map->stripe_len - stripe_offset);
        } else {
                *length = ce->size - offset;
        }

        if (!multi_ret)
                goto out;

        multi->num_stripes = 1;
        stripe_index = 0;
        if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
                if (rw == WRITE)
                        multi->num_stripes = map->num_stripes;
                else if (mirror_num)
                        stripe_index = mirror_num - 1;
                else
                        stripe_index = stripe_nr % map->num_stripes;
        } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
                int factor = map->num_stripes / map->sub_stripes;

                stripe_index = stripe_nr % factor;
                stripe_index *= map->sub_stripes;

                if (rw == WRITE)
                        multi->num_stripes = map->sub_stripes;
                else if (mirror_num)
                        stripe_index += mirror_num - 1;
                else
                        stripe_index = stripe_nr % map->sub_stripes;

                stripe_nr = stripe_nr / factor;
        } else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
                if (rw == WRITE)
                        multi->num_stripes = map->num_stripes;
                else if (mirror_num)
                        stripe_index = mirror_num - 1;
        } else {
                /*
                 * after this do_div call, stripe_nr is the number of stripes
                 * on this device we have to walk to find the data, and
                 * stripe_index is the number of our device in the stripe array
                 */
                stripe_index = stripe_nr % map->num_stripes;
                stripe_nr = stripe_nr / map->num_stripes;
        }
        BUG_ON(stripe_index >= map->num_stripes);

        for (i = 0; i < multi->num_stripes; i++) {
                multi->stripes[i].physical =
                        map->stripes[stripe_index].physical + stripe_offset +
                        stripe_nr * map->stripe_len;
                multi->stripes[i].dev = map->stripes[stripe_index].dev;
                stripe_index++;
        }
        *multi_ret = multi;
out:
        return 0;
}

struct btrfs_device *btrfs_find_device(struct btrfs_root *root, u64 devid,
                                       u8 *uuid, u8 *fsid)
{
        struct btrfs_device *device;
        struct btrfs_fs_devices *cur_devices;

        cur_devices = root->fs_info->fs_devices;
        while (cur_devices) {
                if (!fsid ||
                    !memcmp(cur_devices->fsid, fsid, BTRFS_UUID_SIZE)) {
                        device = __find_device(&cur_devices->devices,
                                               devid, uuid);
                        if (device)
                                return device;
                }
                cur_devices = cur_devices->seed;
        }
        return NULL;
}

int btrfs_bootstrap_super_map(struct btrfs_mapping_tree *map_tree,
                              struct btrfs_fs_devices *fs_devices)
{
        struct map_lookup *map;
        u64 logical = BTRFS_SUPER_INFO_OFFSET;
        u64 length = BTRFS_SUPER_INFO_SIZE;
        int num_stripes = 0;
        int sub_stripes = 0;
        int ret;
        int i;
        struct list_head *cur;

        list_for_each(cur, &fs_devices->devices) {
                num_stripes++;
        }
        map = kmalloc(map_lookup_size(num_stripes), GFP_NOFS);
        if (!map)
                return -ENOMEM;

        map->ce.start = logical;
        map->ce.size = length;
        map->num_stripes = num_stripes;
        map->sub_stripes = sub_stripes;
        map->io_width = length;
        map->io_align = length;
        map->sector_size = length;
        map->stripe_len = length;
        map->type = BTRFS_BLOCK_GROUP_RAID1;

        i = 0;
        list_for_each(cur, &fs_devices->devices) {
                struct btrfs_device *device = list_entry(cur,
                                                         struct btrfs_device,
                                                         dev_list);
                map->stripes[i].physical = logical;
                map->stripes[i].dev = device;
                i++;
        }
        ret = insert_existing_cache_extent(&map_tree->cache_tree, &map->ce);
        if (ret == -EEXIST) {
                struct cache_extent *old;
                struct map_lookup *old_map;
                old = find_cache_extent(&map_tree->cache_tree, logical, length);
                old_map = container_of(old, struct map_lookup, ce);
                remove_cache_extent(&map_tree->cache_tree, old);
                kfree(old_map);
                ret = insert_existing_cache_extent(&map_tree->cache_tree,
                                                   &map->ce);
        }
        BUG_ON(ret);
        return 0;
}

int btrfs_chunk_readonly(struct btrfs_root *root, u64 chunk_offset)
{
        struct cache_extent *ce;
        struct map_lookup *map;
        struct btrfs_mapping_tree *map_tree = &root->fs_info->mapping_tree;
        int readonly = 0;
        int i;

        ce = find_first_cache_extent(&map_tree->cache_tree, chunk_offset);
        BUG_ON(!ce);

        map = container_of(ce, struct map_lookup, ce);
        for (i = 0; i < map->num_stripes; i++) {
                if (!map->stripes[i].dev->writeable) {
                        readonly = 1;
                        break;
                }
        }

        return readonly;
}

static int read_one_chunk(struct btrfs_root *root, struct btrfs_key *key,
                          struct extent_buffer *leaf,
                          struct btrfs_chunk *chunk)
{
        struct btrfs_mapping_tree *map_tree = &root->fs_info->mapping_tree;
        struct map_lookup *map;
        struct cache_extent *ce;
        u64 logical;
        u64 length;
        u64 devid;
        u8 uuid[BTRFS_UUID_SIZE];
        int num_stripes;
        int ret;
        int i;

        logical = key->offset;
        length = btrfs_chunk_length(leaf, chunk);

        ce = find_first_cache_extent(&map_tree->cache_tree, logical);

        /* already mapped? */
        if (ce && ce->start <= logical && ce->start + ce->size > logical) {
                return 0;
        }

        num_stripes = btrfs_chunk_num_stripes(leaf, chunk);
        map = kmalloc(map_lookup_size(num_stripes), GFP_NOFS);
        if (!map)
                return -ENOMEM;

        map->ce.start = logical;
        map->ce.size = length;
        map->num_stripes = num_stripes;
        map->io_width = btrfs_chunk_io_width(leaf, chunk);
        map->io_align = btrfs_chunk_io_align(leaf, chunk);
        map->sector_size = btrfs_chunk_sector_size(leaf, chunk);
        map->stripe_len = btrfs_chunk_stripe_len(leaf, chunk);
        map->type = btrfs_chunk_type(leaf, chunk);
        map->sub_stripes = btrfs_chunk_sub_stripes(leaf, chunk);

        for (i = 0; i < num_stripes; i++) {
                map->stripes[i].physical =
                        btrfs_stripe_offset_nr(leaf, chunk, i);
                devid = btrfs_stripe_devid_nr(leaf, chunk, i);
                read_extent_buffer(leaf, uuid, (unsigned long)
                                   btrfs_stripe_dev_uuid_nr(chunk, i),
                                   BTRFS_UUID_SIZE);
                map->stripes[i].dev = btrfs_find_device(root, devid, uuid,
                                                        NULL);
                if (!map->stripes[i].dev) {
                        kfree(map);
                        return -EIO;
                }

        }
        ret = insert_existing_cache_extent(&map_tree->cache_tree, &map->ce);
        BUG_ON(ret);

        return 0;
}

static int fill_device_from_item(struct extent_buffer *leaf,
                                 struct btrfs_dev_item *dev_item,
                                 struct btrfs_device *device)
{
        unsigned long ptr;

        device->devid = btrfs_device_id(leaf, dev_item);
        device->total_bytes = btrfs_device_total_bytes(leaf, dev_item);
        device->bytes_used = btrfs_device_bytes_used(leaf, dev_item);
        device->type = btrfs_device_type(leaf, dev_item);
        device->io_align = btrfs_device_io_align(leaf, dev_item);
        device->io_width = btrfs_device_io_width(leaf, dev_item);
        device->sector_size = btrfs_device_sector_size(leaf, dev_item);

        ptr = (unsigned long)btrfs_device_uuid(dev_item);
        read_extent_buffer(leaf, device->uuid, ptr, BTRFS_UUID_SIZE);

        return 0;
}

static int open_seed_devices(struct btrfs_root *root, u8 *fsid)
{
        struct btrfs_fs_devices *fs_devices;
        int ret;

        fs_devices = root->fs_info->fs_devices->seed;
        while (fs_devices) {
                if (!memcmp(fs_devices->fsid, fsid, BTRFS_UUID_SIZE)) {
                        ret = 0;
                        goto out;
                }
                fs_devices = fs_devices->seed;
        }

        fs_devices = find_fsid(fsid);
        if (!fs_devices) {
                ret = -ENOENT;
                goto out;
        }

        ret = btrfs_open_devices(fs_devices, O_RDONLY);
        if (ret)
                goto out;

        fs_devices->seed = root->fs_info->fs_devices->seed;
        root->fs_info->fs_devices->seed = fs_devices;
out:
        return ret;
}

static int read_one_dev(struct btrfs_root *root,
                        struct extent_buffer *leaf,
                        struct btrfs_dev_item *dev_item)
{
        struct btrfs_device *device;
        u64 devid;
        int ret = 0;
        u8 fs_uuid[BTRFS_UUID_SIZE];
        u8 dev_uuid[BTRFS_UUID_SIZE];

        devid = btrfs_device_id(leaf, dev_item);
        read_extent_buffer(leaf, dev_uuid,
                           (unsigned long)btrfs_device_uuid(dev_item),
                           BTRFS_UUID_SIZE);
        read_extent_buffer(leaf, fs_uuid,
                           (unsigned long)btrfs_device_fsid(dev_item),
                           BTRFS_UUID_SIZE);

        if (memcmp(fs_uuid, root->fs_info->fsid, BTRFS_UUID_SIZE)) {
                ret = open_seed_devices(root, fs_uuid);
                if (ret)
                        return ret;
        }

        device = btrfs_find_device(root, devid, dev_uuid, fs_uuid);
        if (!device) {
                printk("warning devid %llu not found already\n",
                        (unsigned long long)devid);
                device = kmalloc(sizeof(*device), GFP_NOFS);
                if (!device)
                        return -ENOMEM;
                device->total_ios = 0;
                list_add(&device->dev_list,
                         &root->fs_info->fs_devices->devices);
        }

        fill_device_from_item(leaf, dev_item, device);
        device->dev_root = root->fs_info->dev_root;
        return ret;
}

int btrfs_read_super_device(struct btrfs_root *root, struct extent_buffer *buf)
{
        struct btrfs_dev_item *dev_item;

        dev_item = (struct btrfs_dev_item *)offsetof(struct btrfs_super_block,
                                                     dev_item);
        return read_one_dev(root, buf, dev_item);
}

int btrfs_read_sys_array(struct btrfs_root *root)
{
        struct btrfs_super_block *super_copy = &root->fs_info->super_copy;
        struct extent_buffer *sb;
        struct btrfs_disk_key *disk_key;
        struct btrfs_chunk *chunk;
        struct btrfs_key key;
        u32 num_stripes;
        u32 array_size;
        u32 len = 0;
        u8 *ptr;
        unsigned long sb_ptr;
        u32 cur;
        int ret;

        sb = btrfs_find_create_tree_block(root, BTRFS_SUPER_INFO_OFFSET,
                                          BTRFS_SUPER_INFO_SIZE);
        if (!sb)
                return -ENOMEM;
        btrfs_set_buffer_uptodate(sb);
        write_extent_buffer(sb, super_copy, 0, BTRFS_SUPER_INFO_SIZE);
        array_size = btrfs_super_sys_array_size(super_copy);

        /*
         * we do this loop twice, once for the device items and
         * once for all of the chunks.  This way there are device
         * structs filled in for every chunk
         */
        ptr = super_copy->sys_chunk_array;
        sb_ptr = offsetof(struct btrfs_super_block, sys_chunk_array);
        cur = 0;

        while (cur < array_size) {
                disk_key = (struct btrfs_disk_key *)ptr;
                btrfs_disk_key_to_cpu(&key, disk_key);

                len = sizeof(*disk_key);
                ptr += len;
                sb_ptr += len;
                cur += len;

                if (key.type == BTRFS_CHUNK_ITEM_KEY) {
                        chunk = (struct btrfs_chunk *)sb_ptr;
                        ret = read_one_chunk(root, &key, sb, chunk);
                        BUG_ON(ret);
                        num_stripes = btrfs_chunk_num_stripes(sb, chunk);
                        len = btrfs_chunk_item_size(num_stripes);
                } else {
                        BUG();
                }
                ptr += len;
                sb_ptr += len;
                cur += len;
        }
        free_extent_buffer(sb);
        return 0;
}

int btrfs_read_chunk_tree(struct btrfs_root *root)
{
        struct btrfs_path *path;
        struct extent_buffer *leaf;
        struct btrfs_key key;
        struct btrfs_key found_key;
        int ret;
        int slot;

        root = root->fs_info->chunk_root;

        path = btrfs_alloc_path();
        if (!path)
                return -ENOMEM;

        /* first we search for all of the device items, and then we
         * read in all of the chunk items.  This way we can create chunk
         * mappings that reference all of the devices that are afound
         */
        key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
        key.offset = 0;
        key.type = 0;
again:
        ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
        while(1) {
                leaf = path->nodes[0];
                slot = path->slots[0];
                if (slot >= btrfs_header_nritems(leaf)) {
                        ret = btrfs_next_leaf(root, path);
                        if (ret == 0)
                                continue;
                        if (ret < 0)
                                goto error;
                        break;
                }
                btrfs_item_key_to_cpu(leaf, &found_key, slot);
                if (key.objectid == BTRFS_DEV_ITEMS_OBJECTID) {
                        if (found_key.objectid != BTRFS_DEV_ITEMS_OBJECTID)
                                break;
                        if (found_key.type == BTRFS_DEV_ITEM_KEY) {
                                struct btrfs_dev_item *dev_item;
                                dev_item = btrfs_item_ptr(leaf, slot,
                                                  struct btrfs_dev_item);
                                ret = read_one_dev(root, leaf, dev_item);
                                BUG_ON(ret);
                        }
                } else if (found_key.type == BTRFS_CHUNK_ITEM_KEY) {
                        struct btrfs_chunk *chunk;
                        chunk = btrfs_item_ptr(leaf, slot, struct btrfs_chunk);
                        ret = read_one_chunk(root, &found_key, leaf, chunk);
                        BUG_ON(ret);
                }
                path->slots[0]++;
        }
        if (key.objectid == BTRFS_DEV_ITEMS_OBJECTID) {
                key.objectid = 0;
                btrfs_release_path(root, path);
                goto again;
        }

        btrfs_free_path(path);
        ret = 0;
error:
        return ret;
}

struct list_head *btrfs_scanned_uuids(void)
{
        return &fs_uuids;
}