volumes.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18 #define _XOPEN_SOURCE 600
  19 #define __USE_XOPEN2K
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <sys/types.h>
  23 #include <sys/stat.h>
  24 #include <uuid/uuid.h>
  25 #include <fcntl.h>
  26 #include <unistd.h>
  27 #include "ctree.h"
  28 #include "disk-io.h"
  29 #include "transaction.h"
  30 #include "print-tree.h"
  31 #include "volumes.h"
  32 #include "math.h"
  33
  34 struct stripe {
  35         struct btrfs_device *dev;
  36         u64 physical;
  37 };
  38
  39 static inline int nr_parity_stripes(struct map_lookup *map)
  40 {
  41         if (map->type & BTRFS_BLOCK_GROUP_RAID5)
  42                 return 1;
  43         else if (map->type & BTRFS_BLOCK_GROUP_RAID6)
  44                 return 2;
  45         else
  46                 return 0;
  47 }
  48
  49 static inline int nr_data_stripes(struct map_lookup *map)
  50 {
  51         return map->num_stripes - nr_parity_stripes(map);
  52 }
  53
  54 #define is_parity_stripe(x) ( ((x) == BTRFS_RAID5_P_STRIPE) || ((x) == BTRFS_RAID6_Q_STRIPE) )
  55
  56 static LIST_HEAD(fs_uuids);
  57
  58 static struct btrfs_device *__find_device(struct list_head *head, u64 devid,
  59                                           u8 *uuid)
  60 {
  61         struct btrfs_device *dev;
  62         struct list_head *cur;
  63
  64         list_for_each(cur, head) {
  65                 dev = list_entry(cur, struct btrfs_device, dev_list);
  66                 if (dev->devid == devid &&
  67                     !memcmp(dev->uuid, uuid, BTRFS_UUID_SIZE)) {
  68                         return dev;
  69                 }
  70         }
  71         return NULL;
  72 }
  73
  74 static struct btrfs_fs_devices *find_fsid(u8 *fsid)
  75 {
  76         struct list_head *cur;
  77         struct btrfs_fs_devices *fs_devices;
  78
  79         list_for_each(cur, &fs_uuids) {
  80                 fs_devices = list_entry(cur, struct btrfs_fs_devices, list);
  81                 if (memcmp(fsid, fs_devices->fsid, BTRFS_FSID_SIZE) == 0)
  82                         return fs_devices;
  83         }
  84         return NULL;
  85 }
  86
  87 static int device_list_add(const char *path,
  88                            struct btrfs_super_block *disk_super,
  89                            u64 devid, struct btrfs_fs_devices **fs_devices_ret)
  90 {
  91         struct btrfs_device *device;
  92         struct btrfs_fs_devices *fs_devices;
  93         u64 found_transid = btrfs_super_generation(disk_super);
  94
  95         fs_devices = find_fsid(disk_super->fsid);
  96         if (!fs_devices) {
  97                 fs_devices = kzalloc(sizeof(*fs_devices), GFP_NOFS);
  98                 if (!fs_devices)
  99                         return -ENOMEM;
 100                 INIT_LIST_HEAD(&fs_devices->devices);
 101                 list_add(&fs_devices->list, &fs_uuids);
 102                 memcpy(fs_devices->fsid, disk_super->fsid, BTRFS_FSID_SIZE);
 103                 fs_devices->latest_devid = devid;
 104                 fs_devices->latest_trans = found_transid;
 105                 fs_devices->lowest_devid = (u64)-1;
 106                 device = NULL;
 107         } else {
 108                 device = __find_device(&fs_devices->devices, devid,
 109                                        disk_super->dev_item.uuid);
 110         }
 111         if (!device) {
 112                 device = kzalloc(sizeof(*device), GFP_NOFS);
 113                 if (!device) {
 114                         /* we can safely leave the fs_devices entry around */
 115                         return -ENOMEM;
 116                 }
 117                 device->fd = -1;
 118                 device->devid = devid;
 119                 memcpy(device->uuid, disk_super->dev_item.uuid,
 120                        BTRFS_UUID_SIZE);
 121                 device->name = kstrdup(path, GFP_NOFS);
 122                 if (!device->name) {
 123                         kfree(device);
 124                         return -ENOMEM;
 125                 }
 126                 device->label = kstrdup(disk_super->label, GFP_NOFS);
 127                 if (!device->label) {
 128                         kfree(device->name);
 129                         kfree(device);
 130                         return -ENOMEM;
 131                 }
 132                 device->total_devs = btrfs_super_num_devices(disk_super);
 133                 device->super_bytes_used = btrfs_super_bytes_used(disk_super);
 134                 device->total_bytes =
 135                         btrfs_stack_device_total_bytes(&disk_super->dev_item);
 136                 device->bytes_used =
 137                         btrfs_stack_device_bytes_used(&disk_super->dev_item);
 138                 list_add(&device->dev_list, &fs_devices->devices);
 139                 device->fs_devices = fs_devices;
 140         } else if (!device->name || strcmp(device->name, path)) {
 141                 char *name = strdup(path);
 142                 if (!name)
 143                         return -ENOMEM;
 144                 kfree(device->name);
 145                 device->name = name;
 146         }
 147
 148
 149         if (found_transid > fs_devices->latest_trans) {
 150                 fs_devices->latest_devid = devid;
 151                 fs_devices->latest_trans = found_transid;
 152         }
 153         if (fs_devices->lowest_devid > devid) {
 154                 fs_devices->lowest_devid = devid;
 155         }
 156         *fs_devices_ret = fs_devices;
 157         return 0;
 158 }
 159
 160 int btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
 161 {
 162         struct btrfs_fs_devices *seed_devices;
 163         struct list_head *cur;
 164         struct btrfs_device *device;
 165 again:
 166         list_for_each(cur, &fs_devices->devices) {
 167                 device = list_entry(cur, struct btrfs_device, dev_list);
 168                 if (device->fd != -1) {
 169                         fsync(device->fd);
 170                         if (posix_fadvise(device->fd, 0, 0, POSIX_FADV_DONTNEED))
 171                                 fprintf(stderr, "Warning, could not drop caches\n");
 172                         close(device->fd);
 173                         device->fd = -1;
 174                 }
 175                 device->writeable = 0;
 176         }
 177
 178         seed_devices = fs_devices->seed;
 179         fs_devices->seed = NULL;
 180         if (seed_devices) {
 181                 fs_devices = seed_devices;
 182                 goto again;
 183         }
 184
 185         return 0;
 186 }
 187
 188 int btrfs_open_devices(struct btrfs_fs_devices *fs_devices, int flags)
 189 {
 190         int fd;
 191         struct list_head *head = &fs_devices->devices;
 192         struct list_head *cur;
 193         struct btrfs_device *device;
 194         int ret;
 195
 196         list_for_each(cur, head) {
 197                 device = list_entry(cur, struct btrfs_device, dev_list);
 198                 if (!device->name) {
 199                         printk("no name for device %llu, skip it now\n", device->devid);
 200                         continue;
 201                 }
 202
 203                 fd = open(device->name, flags);
 204                 if (fd < 0) {
 205                         ret = -errno;
 206                         goto fail;
 207                 }
 208
 209                 if (posix_fadvise(fd, 0, 0, POSIX_FADV_DONTNEED))
 210                         fprintf(stderr, "Warning, could not drop caches\n");
 211
 212                 if (device->devid == fs_devices->latest_devid)
 213                         fs_devices->latest_bdev = fd;
 214                 if (device->devid == fs_devices->lowest_devid)
 215                         fs_devices->lowest_bdev = fd;
 216                 device->fd = fd;
 217                 if (flags == O_RDWR)
 218                         device->writeable = 1;
 219         }
 220         return 0;
 221 fail:
 222         btrfs_close_devices(fs_devices);
 223         return ret;
 224 }
 225
 226 int btrfs_scan_one_device(int fd, const char *path,
 227                           struct btrfs_fs_devices **fs_devices_ret,
 228                           u64 *total_devs, u64 super_offset)
 229 {
 230         struct btrfs_super_block *disk_super;
 231         char *buf;
 232         int ret;
 233         u64 devid;
 234
 235         buf = malloc(4096);
 236         if (!buf) {
 237                 ret = -ENOMEM;
 238                 goto error;
 239         }
 240         disk_super = (struct btrfs_super_block *)buf;
 241         ret = btrfs_read_dev_super(fd, disk_super, super_offset);
 242         if (ret < 0) {
 243                 ret = -EIO;
 244                 goto error_brelse;
 245         }
 246         devid = btrfs_stack_device_id(&disk_super->dev_item);
 247         if (btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_METADUMP)
 248                 *total_devs = 1;
 249         else
 250                 *total_devs = btrfs_super_num_devices(disk_super);
 251
 252         ret = device_list_add(path, disk_super, devid, fs_devices_ret);
 253
 254 error_brelse:
 255         free(buf);
 256 error:
 257         return ret;
 258 }
 259
 260 /*
 261  * this uses a pretty simple search, the expectation is that it is
 262  * called very infrequently and that a given device has a small number
 263  * of extents
 264  */
 265 static int find_free_dev_extent(struct btrfs_trans_handle *trans,
 266                                 struct btrfs_device *device,
 267                                 struct btrfs_path *path,
 268                                 u64 num_bytes, u64 *start)
 269 {
 270         struct btrfs_key key;
 271         struct btrfs_root *root = device->dev_root;
 272         struct btrfs_dev_extent *dev_extent = NULL;
 273         u64 hole_size = 0;
 274         u64 last_byte = 0;
 275         u64 search_start = root->fs_info->alloc_start;
 276         u64 search_end = device->total_bytes;
 277         int ret;
 278         int slot = 0;
 279         int start_found;
 280         struct extent_buffer *l;
 281
 282         start_found = 0;
 283         path->reada = 2;
 284
 285         /* FIXME use last free of some kind */
 286
 287         /* we don't want to overwrite the superblock on the drive,
 288          * so we make sure to start at an offset of at least 1MB
 289          */
 290         search_start = max(BTRFS_BLOCK_RESERVED_1M_FOR_SUPER, search_start);
 291
 292         if (search_start >= search_end) {
 293                 ret = -ENOSPC;
 294                 goto error;
 295         }
 296
 297         key.objectid = device->devid;
 298         key.offset = search_start;
 299         key.type = BTRFS_DEV_EXTENT_KEY;
 300         ret = btrfs_search_slot(trans, root, &key, path, 0, 0);
 301         if (ret < 0)
 302                 goto error;
 303         ret = btrfs_previous_item(root, path, 0, key.type);
 304         if (ret < 0)
 305                 goto error;
 306         l = path->nodes[0];
 307         btrfs_item_key_to_cpu(l, &key, path->slots[0]);
 308         while (1) {
 309                 l = path->nodes[0];
 310                 slot = path->slots[0];
 311                 if (slot >= btrfs_header_nritems(l)) {
 312                         ret = btrfs_next_leaf(root, path);
 313                         if (ret == 0)
 314                                 continue;
 315                         if (ret < 0)
 316                                 goto error;
 317 no_more_items:
 318                         if (!start_found) {
 319                                 if (search_start >= search_end) {
 320                                         ret = -ENOSPC;
 321                                         goto error;
 322                                 }
 323                                 *start = search_start;
 324                                 start_found = 1;
 325                                 goto check_pending;
 326                         }
 327                         *start = last_byte > search_start ?
 328                                 last_byte : search_start;
 329                         if (search_end <= *start) {
 330                                 ret = -ENOSPC;
 331                                 goto error;
 332                         }
 333                         goto check_pending;
 334                 }
 335                 btrfs_item_key_to_cpu(l, &key, slot);
 336
 337                 if (key.objectid < device->devid)
 338                         goto next;
 339
 340                 if (key.objectid > device->devid)
 341                         goto no_more_items;
 342
 343                 if (key.offset >= search_start && key.offset > last_byte &&
 344                     start_found) {
 345                         if (last_byte < search_start)
 346                                 last_byte = search_start;
 347                         hole_size = key.offset - last_byte;
 348                         if (key.offset > last_byte &&
 349                             hole_size >= num_bytes) {
 350                                 *start = last_byte;
 351                                 goto check_pending;
 352                         }
 353                 }
 354                 if (btrfs_key_type(&key) != BTRFS_DEV_EXTENT_KEY) {
 355                         goto next;
 356                 }
 357
 358                 start_found = 1;
 359                 dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
 360                 last_byte = key.offset + btrfs_dev_extent_length(l, dev_extent);
 361 next:
 362                 path->slots[0]++;
 363                 cond_resched();
 364         }
 365 check_pending:
 366         /* we have to make sure we didn't find an extent that has already
 367          * been allocated by the map tree or the original allocation
 368          */
 369         btrfs_release_path(path);
 370         BUG_ON(*start < search_start);
 371
 372         if (*start + num_bytes > search_end) {
 373                 ret = -ENOSPC;
 374                 goto error;
 375         }
 376         /* check for pending inserts here */
 377         return 0;
 378
 379 error:
 380         btrfs_release_path(path);
 381         return ret;
 382 }
 383
 384 static int btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
 385                                   struct btrfs_device *device,
 386                                   u64 chunk_tree, u64 chunk_objectid,
 387                                   u64 chunk_offset,
 388                                   u64 num_bytes, u64 *start)
 389 {
 390         int ret;
 391         struct btrfs_path *path;
 392         struct btrfs_root *root = device->dev_root;
 393         struct btrfs_dev_extent *extent;
 394         struct extent_buffer *leaf;
 395         struct btrfs_key key;
 396
 397         path = btrfs_alloc_path();
 398         if (!path)
 399                 return -ENOMEM;
 400
 401         ret = find_free_dev_extent(trans, device, path, num_bytes, start);
 402         if (ret) {
 403                 goto err;
 404         }
 405
 406         key.objectid = device->devid;
 407         key.offset = *start;
 408         key.type = BTRFS_DEV_EXTENT_KEY;
 409         ret = btrfs_insert_empty_item(trans, root, path, &key,
 410                                       sizeof(*extent));
 411         BUG_ON(ret);
 412
 413         leaf = path->nodes[0];
 414         extent = btrfs_item_ptr(leaf, path->slots[0],
 415                                 struct btrfs_dev_extent);
 416         btrfs_set_dev_extent_chunk_tree(leaf, extent, chunk_tree);
 417         btrfs_set_dev_extent_chunk_objectid(leaf, extent, chunk_objectid);
 418         btrfs_set_dev_extent_chunk_offset(leaf, extent, chunk_offset);
 419
 420         write_extent_buffer(leaf, root->fs_info->chunk_tree_uuid,
 421                     (unsigned long)btrfs_dev_extent_chunk_tree_uuid(extent),
 422                     BTRFS_UUID_SIZE);
 423
 424         btrfs_set_dev_extent_length(leaf, extent, num_bytes);
 425         btrfs_mark_buffer_dirty(leaf);
 426 err:
 427         btrfs_free_path(path);
 428         return ret;
 429 }
 430
 431 static int find_next_chunk(struct btrfs_root *root, u64 objectid, u64 *offset)
 432 {
 433         struct btrfs_path *path;
 434         int ret;
 435         struct btrfs_key key;
 436         struct btrfs_chunk *chunk;
 437         struct btrfs_key found_key;
 438
 439         path = btrfs_alloc_path();
 440         BUG_ON(!path);
 441
 442         key.objectid = objectid;
 443         key.offset = (u64)-1;
 444         key.type = BTRFS_CHUNK_ITEM_KEY;
 445
 446         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 447         if (ret < 0)
 448                 goto error;
 449
 450         BUG_ON(ret == 0);
 451
 452         ret = btrfs_previous_item(root, path, 0, BTRFS_CHUNK_ITEM_KEY);
 453         if (ret) {
 454                 *offset = 0;
 455         } else {
 456                 btrfs_item_key_to_cpu(path->nodes[0], &found_key,
 457                                       path->slots[0]);
 458                 if (found_key.objectid != objectid)
 459                         *offset = 0;
 460                 else {
 461                         chunk = btrfs_item_ptr(path->nodes[0], path->slots[0],
 462                                                struct btrfs_chunk);
 463                         *offset = found_key.offset +
 464                                 btrfs_chunk_length(path->nodes[0], chunk);
 465                 }
 466         }
 467         ret = 0;
 468 error:
 469         btrfs_free_path(path);
 470         return ret;
 471 }
 472
 473 static int find_next_devid(struct btrfs_root *root, struct btrfs_path *path,
 474                            u64 *objectid)
 475 {
 476         int ret;
 477         struct btrfs_key key;
 478         struct btrfs_key found_key;
 479
 480         key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
 481         key.type = BTRFS_DEV_ITEM_KEY;
 482         key.offset = (u64)-1;
 483
 484         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 485         if (ret < 0)
 486                 goto error;
 487
 488         BUG_ON(ret == 0);
 489
 490         ret = btrfs_previous_item(root, path, BTRFS_DEV_ITEMS_OBJECTID,
 491                                   BTRFS_DEV_ITEM_KEY);
 492         if (ret) {
 493                 *objectid = 1;
 494         } else {
 495                 btrfs_item_key_to_cpu(path->nodes[0], &found_key,
 496                                       path->slots[0]);
 497                 *objectid = found_key.offset + 1;
 498         }
 499         ret = 0;
 500 error:
 501         btrfs_release_path(path);
 502         return ret;
 503 }
 504
 505 /*
 506  * the device information is stored in the chunk root
 507  * the btrfs_device struct should be fully filled in
 508  */
 509 int btrfs_add_device(struct btrfs_trans_handle *trans,
 510                      struct btrfs_root *root,
 511                      struct btrfs_device *device)
 512 {
 513         int ret;
 514         struct btrfs_path *path;
 515         struct btrfs_dev_item *dev_item;
 516         struct extent_buffer *leaf;
 517         struct btrfs_key key;
 518         unsigned long ptr;
 519         u64 free_devid = 0;
 520
 521         root = root->fs_info->chunk_root;
 522
 523         path = btrfs_alloc_path();
 524         if (!path)
 525                 return -ENOMEM;
 526
 527         ret = find_next_devid(root, path, &free_devid);
 528         if (ret)
 529                 goto out;
 530
 531         key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
 532         key.type = BTRFS_DEV_ITEM_KEY;
 533         key.offset = free_devid;
 534
 535         ret = btrfs_insert_empty_item(trans, root, path, &key,
 536                                       sizeof(*dev_item));
 537         if (ret)
 538                 goto out;
 539
 540         leaf = path->nodes[0];
 541         dev_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dev_item);
 542
 543         device->devid = free_devid;
 544         btrfs_set_device_id(leaf, dev_item, device->devid);
 545         btrfs_set_device_generation(leaf, dev_item, 0);
 546         btrfs_set_device_type(leaf, dev_item, device->type);
 547         btrfs_set_device_io_align(leaf, dev_item, device->io_align);
 548         btrfs_set_device_io_width(leaf, dev_item, device->io_width);
 549         btrfs_set_device_sector_size(leaf, dev_item, device->sector_size);
 550         btrfs_set_device_total_bytes(leaf, dev_item, device->total_bytes);
 551         btrfs_set_device_bytes_used(leaf, dev_item, device->bytes_used);
 552         btrfs_set_device_group(leaf, dev_item, 0);
 553         btrfs_set_device_seek_speed(leaf, dev_item, 0);
 554         btrfs_set_device_bandwidth(leaf, dev_item, 0);
 555         btrfs_set_device_start_offset(leaf, dev_item, 0);
 556
 557         ptr = (unsigned long)btrfs_device_uuid(dev_item);
 558         write_extent_buffer(leaf, device->uuid, ptr, BTRFS_UUID_SIZE);
 559         ptr = (unsigned long)btrfs_device_fsid(dev_item);
 560         write_extent_buffer(leaf, root->fs_info->fsid, ptr, BTRFS_UUID_SIZE);
 561         btrfs_mark_buffer_dirty(leaf);
 562         ret = 0;
 563
 564 out:
 565         btrfs_free_path(path);
 566         return ret;
 567 }
 568
 569 int btrfs_update_device(struct btrfs_trans_handle *trans,
 570                         struct btrfs_device *device)
 571 {
 572         int ret;
 573         struct btrfs_path *path;
 574         struct btrfs_root *root;
 575         struct btrfs_dev_item *dev_item;
 576         struct extent_buffer *leaf;
 577         struct btrfs_key key;
 578
 579         root = device->dev_root->fs_info->chunk_root;
 580
 581         path = btrfs_alloc_path();
 582         if (!path)
 583                 return -ENOMEM;
 584
 585         key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
 586         key.type = BTRFS_DEV_ITEM_KEY;
 587         key.offset = device->devid;
 588
 589         ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
 590         if (ret < 0)
 591                 goto out;
 592
 593         if (ret > 0) {
 594                 ret = -ENOENT;
 595                 goto out;
 596         }
 597
 598         leaf = path->nodes[0];
 599         dev_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dev_item);
 600
 601         btrfs_set_device_id(leaf, dev_item, device->devid);
 602         btrfs_set_device_type(leaf, dev_item, device->type);
 603         btrfs_set_device_io_align(leaf, dev_item, device->io_align);
 604         btrfs_set_device_io_width(leaf, dev_item, device->io_width);
 605         btrfs_set_device_sector_size(leaf, dev_item, device->sector_size);
 606         btrfs_set_device_total_bytes(leaf, dev_item, device->total_bytes);
 607         btrfs_set_device_bytes_used(leaf, dev_item, device->bytes_used);
 608         btrfs_mark_buffer_dirty(leaf);
 609
 610 out:
 611         btrfs_free_path(path);
 612         return ret;
 613 }
 614
 615 int btrfs_add_system_chunk(struct btrfs_trans_handle *trans,
 616                            struct btrfs_root *root,
 617                            struct btrfs_key *key,
 618                            struct btrfs_chunk *chunk, int item_size)
 619 {
 620         struct btrfs_super_block *super_copy = root->fs_info->super_copy;
 621         struct btrfs_disk_key disk_key;
 622         u32 array_size;
 623         u8 *ptr;
 624
 625         array_size = btrfs_super_sys_array_size(super_copy);
 626         if (array_size + item_size > BTRFS_SYSTEM_CHUNK_ARRAY_SIZE)
 627                 return -EFBIG;
 628
 629         ptr = super_copy->sys_chunk_array + array_size;
 630         btrfs_cpu_key_to_disk(&disk_key, key);
 631         memcpy(ptr, &disk_key, sizeof(disk_key));
 632         ptr += sizeof(disk_key);
 633         memcpy(ptr, chunk, item_size);
 634         item_size += sizeof(disk_key);
 635         btrfs_set_super_sys_array_size(super_copy, array_size + item_size);
 636         return 0;
 637 }
 638
 639 static u64 chunk_bytes_by_type(u64 type, u64 calc_size, int num_stripes,
 640                                int sub_stripes)
 641 {
 642         if (type & (BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_DUP))
 643                 return calc_size;
 644         else if (type & BTRFS_BLOCK_GROUP_RAID10)
 645                 return calc_size * (num_stripes / sub_stripes);
 646         else if (type & BTRFS_BLOCK_GROUP_RAID5)
 647                 return calc_size * (num_stripes - 1);
 648         else if (type & BTRFS_BLOCK_GROUP_RAID6)
 649                 return calc_size * (num_stripes - 2);
 650         else
 651                 return calc_size * num_stripes;
 652 }
 653
 654
 655 static u32 find_raid56_stripe_len(u32 data_devices, u32 dev_stripe_target)
 656 {
 657         /* TODO, add a way to store the preferred stripe size */
 658         return 64 * 1024;
 659 }
 660
 661 /*
 662  * btrfs_device_avail_bytes - count bytes available for alloc_chunk
 663  *
 664  * It is not equal to "device->total_bytes - device->bytes_used".
 665  * We do not allocate any chunk in 1M at beginning of device, and not
 666  * allowed to allocate any chunk before alloc_start if it is specified.
 667  * So search holes from max(1M, alloc_start) to device->total_bytes.
 668  */
 669 static int btrfs_device_avail_bytes(struct btrfs_trans_handle *trans,
 670                                     struct btrfs_device *device,
 671                                     u64 *avail_bytes)
 672 {
 673         struct btrfs_path *path;
 674         struct btrfs_root *root = device->dev_root;
 675         struct btrfs_key key;
 676         struct btrfs_dev_extent *dev_extent = NULL;
 677         struct extent_buffer *l;
 678         u64 search_start = root->fs_info->alloc_start;
 679         u64 search_end = device->total_bytes;
 680         u64 extent_end = 0;
 681         u64 free_bytes = 0;
 682         int ret;
 683         int slot = 0;
 684
 685         search_start = max(BTRFS_BLOCK_RESERVED_1M_FOR_SUPER, search_start);
 686
 687         path = btrfs_alloc_path();
 688         if (!path)
 689                 return -ENOMEM;
 690
 691         key.objectid = device->devid;
 692         key.offset = root->fs_info->alloc_start;
 693         key.type = BTRFS_DEV_EXTENT_KEY;
 694
 695         path->reada = 2;
 696         ret = btrfs_search_slot(trans, root, &key, path, 0, 0);
 697         if (ret < 0)
 698                 goto error;
 699         ret = btrfs_previous_item(root, path, 0, key.type);
 700         if (ret < 0)
 701                 goto error;
 702
 703         while (1) {
 704                 l = path->nodes[0];
 705                 slot = path->slots[0];
 706                 if (slot >= btrfs_header_nritems(l)) {
 707                         ret = btrfs_next_leaf(root, path);
 708                         if (ret == 0)
 709                                 continue;
 710                         if (ret < 0)
 711                                 goto error;
 712                         break;
 713                 }
 714                 btrfs_item_key_to_cpu(l, &key, slot);
 715
 716                 if (key.objectid < device->devid)
 717                         goto next;
 718                 if (key.objectid > device->devid)
 719                         break;
 720                 if (btrfs_key_type(&key) != BTRFS_DEV_EXTENT_KEY)
 721                         goto next;
 722                 if (key.offset > search_end)
 723                         break;
 724                 if (key.offset > search_start)
 725                         free_bytes += key.offset - search_start;
 726
 727                 dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
 728                 extent_end = key.offset + btrfs_dev_extent_length(l,
 729                                                                   dev_extent);
 730                 if (extent_end > search_start)
 731                         search_start = extent_end;
 732                 if (search_start > search_end)
 733                         break;
 734 next:
 735                 path->slots[0]++;
 736                 cond_resched();
 737         }
 738
 739         if (search_start < search_end)
 740                 free_bytes += search_end - search_start;
 741
 742         *avail_bytes = free_bytes;
 743         ret = 0;
 744 error:
 745         btrfs_free_path(path);
 746         return ret;
 747 }
 748
 749 int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 750                       struct btrfs_root *extent_root, u64 *start,
 751                       u64 *num_bytes, u64 type)
 752 {
 753         u64 dev_offset;
 754         struct btrfs_fs_info *info = extent_root->fs_info;
 755         struct btrfs_root *chunk_root = info->chunk_root;
 756         struct btrfs_stripe *stripes;
 757         struct btrfs_device *device = NULL;
 758         struct btrfs_chunk *chunk;
 759         struct list_head private_devs;
 760         struct list_head *dev_list = &info->fs_devices->devices;
 761         struct list_head *cur;
 762         struct map_lookup *map;
 763         int min_stripe_size = 1 * 1024 * 1024;
 764         u64 calc_size = 8 * 1024 * 1024;
 765         u64 min_free;
 766         u64 max_chunk_size = 4 * calc_size;
 767         u64 avail = 0;
 768         u64 max_avail = 0;
 769         u64 percent_max;
 770         int num_stripes = 1;
 771         int min_stripes = 1;
 772         int sub_stripes = 0;
 773         int looped = 0;
 774         int ret;
 775         int index;
 776         int stripe_len = 64 * 1024;
 777         struct btrfs_key key;
 778         u64 offset;
 779
 780         if (list_empty(dev_list)) {
 781                 return -ENOSPC;
 782         }
 783
 784         if (type & (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1 |
 785                     BTRFS_BLOCK_GROUP_RAID5 | BTRFS_BLOCK_GROUP_RAID6 |
 786                     BTRFS_BLOCK_GROUP_RAID10 |
 787                     BTRFS_BLOCK_GROUP_DUP)) {
 788                 if (type & BTRFS_BLOCK_GROUP_SYSTEM) {
 789                         calc_size = 8 * 1024 * 1024;
 790                         max_chunk_size = calc_size * 2;
 791                         min_stripe_size = 1 * 1024 * 1024;
 792                 } else if (type & BTRFS_BLOCK_GROUP_DATA) {
 793                         calc_size = 1024 * 1024 * 1024;
 794                         max_chunk_size = 10 * calc_size;
 795                         min_stripe_size = 64 * 1024 * 1024;
 796                 } else if (type & BTRFS_BLOCK_GROUP_METADATA) {
 797                         calc_size = 1024 * 1024 * 1024;
 798                         max_chunk_size = 4 * calc_size;
 799                         min_stripe_size = 32 * 1024 * 1024;
 800                 }
 801         }
 802         if (type & BTRFS_BLOCK_GROUP_RAID1) {
 803                 num_stripes = min_t(u64, 2,
 804                                   btrfs_super_num_devices(info->super_copy));
 805                 if (num_stripes < 2)
 806                         return -ENOSPC;
 807                 min_stripes = 2;
 808         }
 809         if (type & BTRFS_BLOCK_GROUP_DUP) {
 810                 num_stripes = 2;
 811                 min_stripes = 2;
 812         }
 813         if (type & (BTRFS_BLOCK_GROUP_RAID0)) {
 814                 num_stripes = btrfs_super_num_devices(info->super_copy);
 815                 min_stripes = 2;
 816         }
 817         if (type & (BTRFS_BLOCK_GROUP_RAID10)) {
 818                 num_stripes = btrfs_super_num_devices(info->super_copy);
 819                 if (num_stripes < 4)
 820                         return -ENOSPC;
 821                 num_stripes &= ~(u32)1;
 822                 sub_stripes = 2;
 823                 min_stripes = 4;
 824         }
 825         if (type & (BTRFS_BLOCK_GROUP_RAID5)) {
 826                 num_stripes = btrfs_super_num_devices(info->super_copy);
 827                 if (num_stripes < 2)
 828                         return -ENOSPC;
 829                 min_stripes = 2;
 830                 stripe_len = find_raid56_stripe_len(num_stripes - 1,
 831                                     btrfs_super_stripesize(info->super_copy));
 832         }
 833         if (type & (BTRFS_BLOCK_GROUP_RAID6)) {
 834                 num_stripes = btrfs_super_num_devices(info->super_copy);
 835                 if (num_stripes < 3)
 836                         return -ENOSPC;
 837                 min_stripes = 3;
 838                 stripe_len = find_raid56_stripe_len(num_stripes - 2,
 839                                     btrfs_super_stripesize(info->super_copy));
 840         }
 841
 842         /* we don't want a chunk larger than 10% of the FS */
 843         percent_max = div_factor(btrfs_super_total_bytes(info->super_copy), 1);
 844         max_chunk_size = min(percent_max, max_chunk_size);
 845
 846 again:
 847         if (chunk_bytes_by_type(type, calc_size, num_stripes, sub_stripes) >
 848             max_chunk_size) {
 849                 calc_size = max_chunk_size;
 850                 calc_size /= num_stripes;
 851                 calc_size /= stripe_len;
 852                 calc_size *= stripe_len;
 853         }
 854         /* we don't want tiny stripes */
 855         calc_size = max_t(u64, calc_size, min_stripe_size);
 856
 857         calc_size /= stripe_len;
 858         calc_size *= stripe_len;
 859         INIT_LIST_HEAD(&private_devs);
 860         cur = dev_list->next;
 861         index = 0;
 862
 863         if (type & BTRFS_BLOCK_GROUP_DUP)
 864                 min_free = calc_size * 2;
 865         else
 866                 min_free = calc_size;
 867
 868         /* build a private list of devices we will allocate from */
 869         while(index < num_stripes) {
 870                 device = list_entry(cur, struct btrfs_device, dev_list);
 871                 ret = btrfs_device_avail_bytes(trans, device, &avail);
 872                 if (ret)
 873                         return ret;
 874                 cur = cur->next;
 875                 if (avail >= min_free) {
 876                         list_move_tail(&device->dev_list, &private_devs);
 877                         index++;
 878                         if (type & BTRFS_BLOCK_GROUP_DUP)
 879                                 index++;
 880                 } else if (avail > max_avail)
 881                         max_avail = avail;
 882                 if (cur == dev_list)
 883                         break;
 884         }
 885         if (index < num_stripes) {
 886                 list_splice(&private_devs, dev_list);
 887                 if (index >= min_stripes) {
 888                         num_stripes = index;
 889                         if (type & (BTRFS_BLOCK_GROUP_RAID10)) {
 890                                 num_stripes /= sub_stripes;
 891                                 num_stripes *= sub_stripes;
 892                         }
 893                         looped = 1;
 894                         goto again;
 895                 }
 896                 if (!looped && max_avail > 0) {
 897                         looped = 1;
 898                         calc_size = max_avail;
 899                         goto again;
 900                 }
 901                 return -ENOSPC;
 902         }
 903         ret = find_next_chunk(chunk_root, BTRFS_FIRST_CHUNK_TREE_OBJECTID,
 904                               &offset);
 905         if (ret)
 906                 return ret;
 907         key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
 908         key.type = BTRFS_CHUNK_ITEM_KEY;
 909         key.offset = offset;
 910
 911         chunk = kmalloc(btrfs_chunk_item_size(num_stripes), GFP_NOFS);
 912         if (!chunk)
 913                 return -ENOMEM;
 914
 915         map = kmalloc(btrfs_map_lookup_size(num_stripes), GFP_NOFS);
 916         if (!map) {
 917                 kfree(chunk);
 918                 return -ENOMEM;
 919         }
 920
 921         stripes = &chunk->stripe;
 922         *num_bytes = chunk_bytes_by_type(type, calc_size,
 923                                          num_stripes, sub_stripes);
 924         index = 0;
 925         while(index < num_stripes) {
 926                 struct btrfs_stripe *stripe;
 927                 BUG_ON(list_empty(&private_devs));
 928                 cur = private_devs.next;
 929                 device = list_entry(cur, struct btrfs_device, dev_list);
 930
 931                 /* loop over this device again if we're doing a dup group */
 932                 if (!(type & BTRFS_BLOCK_GROUP_DUP) ||
 933                     (index == num_stripes - 1))
 934                         list_move_tail(&device->dev_list, dev_list);
 935
 936                 ret = btrfs_alloc_dev_extent(trans, device,
 937                              info->chunk_root->root_key.objectid,
 938                              BTRFS_FIRST_CHUNK_TREE_OBJECTID, key.offset,
 939                              calc_size, &dev_offset);
 940                 BUG_ON(ret);
 941
 942                 device->bytes_used += calc_size;
 943                 ret = btrfs_update_device(trans, device);
 944                 BUG_ON(ret);
 945
 946                 map->stripes[index].dev = device;
 947                 map->stripes[index].physical = dev_offset;
 948                 stripe = stripes + index;
 949                 btrfs_set_stack_stripe_devid(stripe, device->devid);
 950                 btrfs_set_stack_stripe_offset(stripe, dev_offset);
 951                 memcpy(stripe->dev_uuid, device->uuid, BTRFS_UUID_SIZE);
 952                 index++;
 953         }
 954         BUG_ON(!list_empty(&private_devs));
 955
 956         /* key was set above */
 957         btrfs_set_stack_chunk_length(chunk, *num_bytes);
 958         btrfs_set_stack_chunk_owner(chunk, extent_root->root_key.objectid);
 959         btrfs_set_stack_chunk_stripe_len(chunk, stripe_len);
 960         btrfs_set_stack_chunk_type(chunk, type);
 961         btrfs_set_stack_chunk_num_stripes(chunk, num_stripes);
 962         btrfs_set_stack_chunk_io_align(chunk, stripe_len);
 963         btrfs_set_stack_chunk_io_width(chunk, stripe_len);
 964         btrfs_set_stack_chunk_sector_size(chunk, extent_root->sectorsize);
 965         btrfs_set_stack_chunk_sub_stripes(chunk, sub_stripes);
 966         map->sector_size = extent_root->sectorsize;
 967         map->stripe_len = stripe_len;
 968         map->io_align = stripe_len;
 969         map->io_width = stripe_len;
 970         map->type = type;
 971         map->num_stripes = num_stripes;
 972         map->sub_stripes = sub_stripes;
 973
 974         ret = btrfs_insert_item(trans, chunk_root, &key, chunk,
 975                                 btrfs_chunk_item_size(num_stripes));
 976         BUG_ON(ret);
 977         *start = key.offset;;
 978
 979         map->ce.start = key.offset;
 980         map->ce.size = *num_bytes;
 981
 982         ret = insert_cache_extent(&info->mapping_tree.cache_tree, &map->ce);
 983         BUG_ON(ret);
 984
 985         if (type & BTRFS_BLOCK_GROUP_SYSTEM) {
 986                 ret = btrfs_add_system_chunk(trans, chunk_root, &key,
 987                                     chunk, btrfs_chunk_item_size(num_stripes));
 988                 BUG_ON(ret);
 989         }
 990
 991         kfree(chunk);
 992         return ret;
 993 }
 994
 995 int btrfs_alloc_data_chunk(struct btrfs_trans_handle *trans,
 996                            struct btrfs_root *extent_root, u64 *start,
 997                            u64 num_bytes, u64 type)
 998 {
 999         u64 dev_offset;
1000         struct btrfs_fs_info *info = extent_root->fs_info;
1001         struct btrfs_root *chunk_root = info->chunk_root;
1002         struct btrfs_stripe *stripes;
1003         struct btrfs_device *device = NULL;
1004         struct btrfs_chunk *chunk;
1005         struct list_head *dev_list = &info->fs_devices->devices;
1006         struct list_head *cur;
1007         struct map_lookup *map;
1008         u64 calc_size = 8 * 1024 * 1024;
1009         int num_stripes = 1;
1010         int sub_stripes = 0;
1011         int ret;
1012         int index;
1013         int stripe_len = 64 * 1024;
1014         struct btrfs_key key;
1015
1016         key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
1017         key.type = BTRFS_CHUNK_ITEM_KEY;
1018         ret = find_next_chunk(chunk_root, BTRFS_FIRST_CHUNK_TREE_OBJECTID,
1019                               &key.offset);
1020         if (ret)
1021                 return ret;
1022
1023         chunk = kmalloc(btrfs_chunk_item_size(num_stripes), GFP_NOFS);
1024         if (!chunk)
1025                 return -ENOMEM;
1026
1027         map = kmalloc(btrfs_map_lookup_size(num_stripes), GFP_NOFS);
1028         if (!map) {
1029                 kfree(chunk);
1030                 return -ENOMEM;
1031         }
1032
1033         stripes = &chunk->stripe;
1034         calc_size = num_bytes;
1035
1036         index = 0;
1037         cur = dev_list->next;
1038         device = list_entry(cur, struct btrfs_device, dev_list);
1039
1040         while (index < num_stripes) {
1041                 struct btrfs_stripe *stripe;
1042
1043                 ret = btrfs_alloc_dev_extent(trans, device,
1044                              info->chunk_root->root_key.objectid,
1045                              BTRFS_FIRST_CHUNK_TREE_OBJECTID, key.offset,
1046                              calc_size, &dev_offset);
1047                 BUG_ON(ret);
1048
1049                 device->bytes_used += calc_size;
1050                 ret = btrfs_update_device(trans, device);
1051                 BUG_ON(ret);
1052
1053                 map->stripes[index].dev = device;
1054                 map->stripes[index].physical = dev_offset;
1055                 stripe = stripes + index;
1056                 btrfs_set_stack_stripe_devid(stripe, device->devid);
1057                 btrfs_set_stack_stripe_offset(stripe, dev_offset);
1058                 memcpy(stripe->dev_uuid, device->uuid, BTRFS_UUID_SIZE);
1059                 index++;
1060         }
1061
1062         /* key was set above */
1063         btrfs_set_stack_chunk_length(chunk, num_bytes);
1064         btrfs_set_stack_chunk_owner(chunk, extent_root->root_key.objectid);
1065         btrfs_set_stack_chunk_stripe_len(chunk, stripe_len);
1066         btrfs_set_stack_chunk_type(chunk, type);
1067         btrfs_set_stack_chunk_num_stripes(chunk, num_stripes);
1068         btrfs_set_stack_chunk_io_align(chunk, stripe_len);
1069         btrfs_set_stack_chunk_io_width(chunk, stripe_len);
1070         btrfs_set_stack_chunk_sector_size(chunk, extent_root->sectorsize);
1071         btrfs_set_stack_chunk_sub_stripes(chunk, sub_stripes);
1072         map->sector_size = extent_root->sectorsize;
1073         map->stripe_len = stripe_len;
1074         map->io_align = stripe_len;
1075         map->io_width = stripe_len;
1076         map->type = type;
1077         map->num_stripes = num_stripes;
1078         map->sub_stripes = sub_stripes;
1079
1080         ret = btrfs_insert_item(trans, chunk_root, &key, chunk,
1081                                 btrfs_chunk_item_size(num_stripes));
1082         BUG_ON(ret);
1083         *start = key.offset;
1084
1085         map->ce.start = key.offset;
1086         map->ce.size = num_bytes;
1087
1088         ret = insert_cache_extent(&info->mapping_tree.cache_tree, &map->ce);
1089         BUG_ON(ret);
1090
1091         kfree(chunk);
1092         return ret;
1093 }
1094
1095 int btrfs_num_copies(struct btrfs_mapping_tree *map_tree, u64 logical, u64 len)
1096 {
1097         struct cache_extent *ce;
1098         struct map_lookup *map;
1099         int ret;
1100
1101         ce = search_cache_extent(&map_tree->cache_tree, logical);
1102         BUG_ON(!ce);
1103         BUG_ON(ce->start > logical || ce->start + ce->size < logical);
1104         map = container_of(ce, struct map_lookup, ce);
1105
1106         if (map->type & (BTRFS_BLOCK_GROUP_DUP | BTRFS_BLOCK_GROUP_RAID1))
1107                 ret = map->num_stripes;
1108         else if (map->type & BTRFS_BLOCK_GROUP_RAID10)
1109                 ret = map->sub_stripes;
1110         else if (map->type & BTRFS_BLOCK_GROUP_RAID5)
1111                 ret = 2;
1112         else if (map->type & BTRFS_BLOCK_GROUP_RAID6)
1113                 ret = 3;
1114         else
1115                 ret = 1;
1116         return ret;
1117 }
1118
1119 int btrfs_next_metadata(struct btrfs_mapping_tree *map_tree, u64 *logical,
1120                         u64 *size)
1121 {
1122         struct cache_extent *ce;
1123         struct map_lookup *map;
1124
1125         ce = search_cache_extent(&map_tree->cache_tree, *logical);
1126
1127         while (ce) {
1128                 ce = next_cache_extent(ce);
1129                 if (!ce)
1130                         return -ENOENT;
1131
1132                 map = container_of(ce, struct map_lookup, ce);
1133                 if (map->type & BTRFS_BLOCK_GROUP_METADATA) {
1134                         *logical = ce->start;
1135                         *size = ce->size;
1136                         return 0;
1137                 }
1138         }
1139
1140         return -ENOENT;
1141 }
1142
1143 int btrfs_rmap_block(struct btrfs_mapping_tree *map_tree,
1144                      u64 chunk_start, u64 physical, u64 devid,
1145                      u64 **logical, int *naddrs, int *stripe_len)
1146 {
1147         struct cache_extent *ce;
1148         struct map_lookup *map;
1149         u64 *buf;
1150         u64 bytenr;
1151         u64 length;
1152         u64 stripe_nr;
1153         u64 rmap_len;
1154         int i, j, nr = 0;
1155
1156         ce = search_cache_extent(&map_tree->cache_tree, chunk_start);
1157         BUG_ON(!ce);
1158         map = container_of(ce, struct map_lookup, ce);
1159
1160         length = ce->size;
1161         rmap_len = map->stripe_len;
1162         if (map->type & BTRFS_BLOCK_GROUP_RAID10)
1163                 length = ce->size / (map->num_stripes / map->sub_stripes);
1164         else if (map->type & BTRFS_BLOCK_GROUP_RAID0)
1165                 length = ce->size / map->num_stripes;
1166         else if (map->type & (BTRFS_BLOCK_GROUP_RAID5 |
1167                               BTRFS_BLOCK_GROUP_RAID6)) {
1168                 length = ce->size / nr_data_stripes(map);
1169                 rmap_len = map->stripe_len * nr_data_stripes(map);
1170         }
1171
1172         buf = kzalloc(sizeof(u64) * map->num_stripes, GFP_NOFS);
1173
1174         for (i = 0; i < map->num_stripes; i++) {
1175                 if (devid && map->stripes[i].dev->devid != devid)
1176                         continue;
1177                 if (map->stripes[i].physical > physical ||
1178                     map->stripes[i].physical + length <= physical)
1179                         continue;
1180
1181                 stripe_nr = (physical - map->stripes[i].physical) /
1182                             map->stripe_len;
1183
1184                 if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
1185                         stripe_nr = (stripe_nr * map->num_stripes + i) /
1186                                     map->sub_stripes;
1187                 } else if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
1188                         stripe_nr = stripe_nr * map->num_stripes + i;
1189                 } /* else if RAID[56], multiply by nr_data_stripes().
1190                    * Alternatively, just use rmap_len below instead of
1191                    * map->stripe_len */
1192
1193                 bytenr = ce->start + stripe_nr * rmap_len;
1194                 for (j = 0; j < nr; j++) {
1195                         if (buf[j] == bytenr)
1196                                 break;
1197                 }
1198                 if (j == nr)
1199                         buf[nr++] = bytenr;
1200         }
1201
1202         *logical = buf;
1203         *naddrs = nr;
1204         *stripe_len = rmap_len;
1205
1206         return 0;
1207 }
1208
1209 static inline int parity_smaller(u64 a, u64 b)
1210 {
1211         return a > b;
1212 }
1213
1214 /* Bubble-sort the stripe set to put the parity/syndrome stripes last */
1215 static void sort_parity_stripes(struct btrfs_multi_bio *bbio, u64 *raid_map)
1216 {
1217         struct btrfs_bio_stripe s;
1218         int i;
1219         u64 l;
1220         int again = 1;
1221
1222         while (again) {
1223                 again = 0;
1224                 for (i = 0; i < bbio->num_stripes - 1; i++) {
1225                         if (parity_smaller(raid_map[i], raid_map[i+1])) {
1226                                 s = bbio->stripes[i];
1227                                 l = raid_map[i];
1228                                 bbio->stripes[i] = bbio->stripes[i+1];
1229                                 raid_map[i] = raid_map[i+1];
1230                                 bbio->stripes[i+1] = s;
1231                                 raid_map[i+1] = l;
1232                                 again = 1;
1233                         }
1234                 }
1235         }
1236 }
1237
1238 int btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,
1239                     u64 logical, u64 *length,
1240                     struct btrfs_multi_bio **multi_ret, int mirror_num,
1241                     u64 **raid_map_ret)
1242 {
1243         return __btrfs_map_block(map_tree, rw, logical, length, NULL,
1244                                  multi_ret, mirror_num, raid_map_ret);
1245 }
1246
1247 int __btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,
1248                     u64 logical, u64 *length, u64 *type,
1249                     struct btrfs_multi_bio **multi_ret, int mirror_num,
1250                     u64 **raid_map_ret)
1251 {
1252         struct cache_extent *ce;
1253         struct map_lookup *map;
1254         u64 offset;
1255         u64 stripe_offset;
1256         u64 stripe_nr;
1257         u64 *raid_map = NULL;
1258         int stripes_allocated = 8;
1259         int stripes_required = 1;
1260         int stripe_index;
1261         int i;
1262         struct btrfs_multi_bio *multi = NULL;
1263
1264         if (multi_ret && rw == READ) {
1265                 stripes_allocated = 1;
1266         }
1267 again:
1268         ce = search_cache_extent(&map_tree->cache_tree, logical);
1269         if (!ce) {
1270                 if (multi)
1271                         kfree(multi);
1272                 return -ENOENT;
1273         }
1274         if (ce->start > logical || ce->start + ce->size < logical) {
1275                 if (multi)
1276                         kfree(multi);
1277                 return -ENOENT;
1278         }
1279
1280         if (multi_ret) {
1281                 multi = kzalloc(btrfs_multi_bio_size(stripes_allocated),
1282                                 GFP_NOFS);
1283                 if (!multi)
1284                         return -ENOMEM;
1285         }
1286         map = container_of(ce, struct map_lookup, ce);
1287         offset = logical - ce->start;
1288
1289         if (rw == WRITE) {
1290                 if (map->type & (BTRFS_BLOCK_GROUP_RAID1 |
1291                                  BTRFS_BLOCK_GROUP_DUP)) {
1292                         stripes_required = map->num_stripes;
1293                 } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
1294                         stripes_required = map->sub_stripes;
1295                 }
1296         }
1297         if (map->type & (BTRFS_BLOCK_GROUP_RAID5 | BTRFS_BLOCK_GROUP_RAID6)
1298             && multi_ret && ((rw & WRITE) || mirror_num > 1) && raid_map_ret) {
1299                     /* RAID[56] write or recovery. Return all stripes */
1300                     stripes_required = map->num_stripes;
1301
1302                     /* Only allocate the map if we've already got a large enough multi_ret */
1303                     if (stripes_allocated >= stripes_required) {
1304                             raid_map = kmalloc(sizeof(u64) * map->num_stripes, GFP_NOFS);
1305                             if (!raid_map) {
1306                                     kfree(multi);
1307                                     return -ENOMEM;
1308                             }
1309                     }
1310         }
1311
1312         /* if our multi bio struct is too small, back off and try again */
1313         if (multi_ret && stripes_allocated < stripes_required) {
1314                 stripes_allocated = stripes_required;
1315                 kfree(multi);
1316                 multi = NULL;
1317                 goto again;
1318         }
1319         stripe_nr = offset;
1320         /*
1321          * stripe_nr counts the total number of stripes we have to stride
1322          * to get to this block
1323          */
1324         stripe_nr = stripe_nr / map->stripe_len;
1325
1326         stripe_offset = stripe_nr * map->stripe_len;
1327         BUG_ON(offset < stripe_offset);
1328
1329         /* stripe_offset is the offset of this block in its stripe*/
1330         stripe_offset = offset - stripe_offset;
1331
1332         if (map->type & (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1 |
1333                          BTRFS_BLOCK_GROUP_RAID5 | BTRFS_BLOCK_GROUP_RAID6 |
1334                          BTRFS_BLOCK_GROUP_RAID10 |
1335                          BTRFS_BLOCK_GROUP_DUP)) {
1336                 /* we limit the length of each bio to what fits in a stripe */
1337                 *length = min_t(u64, ce->size - offset,
1338                               map->stripe_len - stripe_offset);
1339         } else {
1340                 *length = ce->size - offset;
1341         }
1342
1343         if (!multi_ret)
1344                 goto out;
1345
1346         multi->num_stripes = 1;
1347         stripe_index = 0;
1348         if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
1349                 if (rw == WRITE)
1350                         multi->num_stripes = map->num_stripes;
1351                 else if (mirror_num)
1352                         stripe_index = mirror_num - 1;
1353                 else
1354                         stripe_index = stripe_nr % map->num_stripes;
1355         } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
1356                 int factor = map->num_stripes / map->sub_stripes;
1357
1358                 stripe_index = stripe_nr % factor;
1359                 stripe_index *= map->sub_stripes;
1360
1361                 if (rw == WRITE)
1362                         multi->num_stripes = map->sub_stripes;
1363                 else if (mirror_num)
1364                         stripe_index += mirror_num - 1;
1365
1366                 stripe_nr = stripe_nr / factor;
1367         } else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
1368                 if (rw == WRITE)
1369                         multi->num_stripes = map->num_stripes;
1370                 else if (mirror_num)
1371                         stripe_index = mirror_num - 1;
1372         } else if (map->type & (BTRFS_BLOCK_GROUP_RAID5 |
1373                                 BTRFS_BLOCK_GROUP_RAID6)) {
1374
1375                 if (raid_map) {
1376                         int rot;
1377                         u64 tmp;
1378                         u64 raid56_full_stripe_start;
1379                         u64 full_stripe_len = nr_data_stripes(map) * map->stripe_len;
1380
1381                         /*
1382                          * align the start of our data stripe in the logical
1383                          * address space
1384                          */
1385                         raid56_full_stripe_start = offset / full_stripe_len;
1386                         raid56_full_stripe_start *= full_stripe_len;
1387
1388                         /* get the data stripe number */
1389                         stripe_nr = raid56_full_stripe_start / map->stripe_len;
1390                         stripe_nr = stripe_nr / nr_data_stripes(map);
1391
1392                         /* Work out the disk rotation on this stripe-set */
1393                         rot = stripe_nr % map->num_stripes;
1394
1395                         /* Fill in the logical address of each stripe */
1396                         tmp = stripe_nr * nr_data_stripes(map);
1397
1398                         for (i = 0; i < nr_data_stripes(map); i++)
1399                                 raid_map[(i+rot) % map->num_stripes] =
1400                                         ce->start + (tmp + i) * map->stripe_len;
1401
1402                         raid_map[(i+rot) % map->num_stripes] = BTRFS_RAID5_P_STRIPE;
1403                         if (map->type & BTRFS_BLOCK_GROUP_RAID6)
1404                                 raid_map[(i+rot+1) % map->num_stripes] = BTRFS_RAID6_Q_STRIPE;
1405
1406                         *length = map->stripe_len;
1407                         stripe_index = 0;
1408                         stripe_offset = 0;
1409                         multi->num_stripes = map->num_stripes;
1410                 } else {
1411                         stripe_index = stripe_nr % nr_data_stripes(map);
1412                         stripe_nr = stripe_nr / nr_data_stripes(map);
1413
1414                         /*
1415                          * Mirror #0 or #1 means the original data block.
1416                          * Mirror #2 is RAID5 parity block.
1417                          * Mirror #3 is RAID6 Q block.
1418                          */
1419                         if (mirror_num > 1)
1420                                 stripe_index = nr_data_stripes(map) + mirror_num - 2;
1421
1422                         /* We distribute the parity blocks across stripes */
1423                         stripe_index = (stripe_nr + stripe_index) % map->num_stripes;
1424                 }
1425         } else {
1426                 /*
1427                  * after this do_div call, stripe_nr is the number of stripes
1428                  * on this device we have to walk to find the data, and
1429                  * stripe_index is the number of our device in the stripe array
1430                  */
1431                 stripe_index = stripe_nr % map->num_stripes;
1432                 stripe_nr = stripe_nr / map->num_stripes;
1433         }
1434         BUG_ON(stripe_index >= map->num_stripes);
1435
1436         for (i = 0; i < multi->num_stripes; i++) {
1437                 multi->stripes[i].physical =
1438                         map->stripes[stripe_index].physical + stripe_offset +
1439                         stripe_nr * map->stripe_len;
1440                 multi->stripes[i].dev = map->stripes[stripe_index].dev;
1441                 stripe_index++;
1442         }
1443         *multi_ret = multi;
1444
1445         if (type)
1446                 *type = map->type;
1447
1448         if (raid_map) {
1449                 sort_parity_stripes(multi, raid_map);
1450                 *raid_map_ret = raid_map;
1451         }
1452 out:
1453         return 0;
1454 }
1455
1456 struct btrfs_device *btrfs_find_device(struct btrfs_root *root, u64 devid,
1457                                        u8 *uuid, u8 *fsid)
1458 {
1459         struct btrfs_device *device;
1460         struct btrfs_fs_devices *cur_devices;
1461
1462         cur_devices = root->fs_info->fs_devices;
1463         while (cur_devices) {
1464                 if (!fsid ||
1465                     !memcmp(cur_devices->fsid, fsid, BTRFS_UUID_SIZE)) {
1466                         device = __find_device(&cur_devices->devices,
1467                                                devid, uuid);
1468                         if (device)
1469                                 return device;
1470                 }
1471                 cur_devices = cur_devices->seed;
1472         }
1473         return NULL;
1474 }
1475
1476 struct btrfs_device *
1477 btrfs_find_device_by_devid(struct btrfs_fs_devices *fs_devices,
1478                            u64 devid, int instance)
1479 {
1480         struct list_head *head = &fs_devices->devices;
1481         struct btrfs_device *dev;
1482         int num_found = 0;
1483
1484         list_for_each_entry(dev, head, dev_list) {
1485                 if (dev->devid == devid && num_found++ == instance)
1486                         return dev;
1487         }
1488         return NULL;
1489 }
1490
1491 int btrfs_chunk_readonly(struct btrfs_root *root, u64 chunk_offset)
1492 {
1493         struct cache_extent *ce;
1494         struct map_lookup *map;
1495         struct btrfs_mapping_tree *map_tree = &root->fs_info->mapping_tree;
1496         int readonly = 0;
1497         int i;
1498
1499         ce = search_cache_extent(&map_tree->cache_tree, chunk_offset);
1500         BUG_ON(!ce);
1501
1502         map = container_of(ce, struct map_lookup, ce);
1503         for (i = 0; i < map->num_stripes; i++) {
1504                 if (!map->stripes[i].dev->writeable) {
1505                         readonly = 1;
1506                         break;
1507                 }
1508         }
1509
1510         return readonly;
1511 }
1512
1513 static struct btrfs_device *fill_missing_device(u64 devid)
1514 {
1515         struct btrfs_device *device;
1516
1517         device = kzalloc(sizeof(*device), GFP_NOFS);
1518         device->devid = devid;
1519         device->fd = -1;
1520         return device;
1521 }
1522
1523 static int read_one_chunk(struct btrfs_root *root, struct btrfs_key *key,
1524                           struct extent_buffer *leaf,
1525                           struct btrfs_chunk *chunk)
1526 {
1527         struct btrfs_mapping_tree *map_tree = &root->fs_info->mapping_tree;
1528         struct map_lookup *map;
1529         struct cache_extent *ce;
1530         u64 logical;
1531         u64 length;
1532         u64 devid;
1533         u8 uuid[BTRFS_UUID_SIZE];
1534         int num_stripes;
1535         int ret;
1536         int i;
1537
1538         logical = key->offset;
1539         length = btrfs_chunk_length(leaf, chunk);
1540
1541         ce = search_cache_extent(&map_tree->cache_tree, logical);
1542
1543         /* already mapped? */
1544         if (ce && ce->start <= logical && ce->start + ce->size > logical) {
1545                 return 0;
1546         }
1547
1548         num_stripes = btrfs_chunk_num_stripes(leaf, chunk);
1549         map = kmalloc(btrfs_map_lookup_size(num_stripes), GFP_NOFS);
1550         if (!map)
1551                 return -ENOMEM;
1552
1553         map->ce.start = logical;
1554         map->ce.size = length;
1555         map->num_stripes = num_stripes;
1556         map->io_width = btrfs_chunk_io_width(leaf, chunk);
1557         map->io_align = btrfs_chunk_io_align(leaf, chunk);
1558         map->sector_size = btrfs_chunk_sector_size(leaf, chunk);
1559         map->stripe_len = btrfs_chunk_stripe_len(leaf, chunk);
1560         map->type = btrfs_chunk_type(leaf, chunk);
1561         map->sub_stripes = btrfs_chunk_sub_stripes(leaf, chunk);
1562
1563         for (i = 0; i < num_stripes; i++) {
1564                 map->stripes[i].physical =
1565                         btrfs_stripe_offset_nr(leaf, chunk, i);
1566                 devid = btrfs_stripe_devid_nr(leaf, chunk, i);
1567                 read_extent_buffer(leaf, uuid, (unsigned long)
1568                                    btrfs_stripe_dev_uuid_nr(chunk, i),
1569                                    BTRFS_UUID_SIZE);
1570                 map->stripes[i].dev = btrfs_find_device(root, devid, uuid,
1571                                                         NULL);
1572                 if (!map->stripes[i].dev) {
1573                         map->stripes[i].dev = fill_missing_device(devid);
1574                         printf("warning, device %llu is missing\n",
1575                                (unsigned long long)devid);
1576                 }
1577
1578         }
1579         ret = insert_cache_extent(&map_tree->cache_tree, &map->ce);
1580         BUG_ON(ret);
1581
1582         return 0;
1583 }
1584
1585 static int fill_device_from_item(struct extent_buffer *leaf,
1586                                  struct btrfs_dev_item *dev_item,
1587                                  struct btrfs_device *device)
1588 {
1589         unsigned long ptr;
1590
1591         device->devid = btrfs_device_id(leaf, dev_item);
1592         device->total_bytes = btrfs_device_total_bytes(leaf, dev_item);
1593         device->bytes_used = btrfs_device_bytes_used(leaf, dev_item);
1594         device->type = btrfs_device_type(leaf, dev_item);
1595         device->io_align = btrfs_device_io_align(leaf, dev_item);
1596         device->io_width = btrfs_device_io_width(leaf, dev_item);
1597         device->sector_size = btrfs_device_sector_size(leaf, dev_item);
1598
1599         ptr = (unsigned long)btrfs_device_uuid(dev_item);
1600         read_extent_buffer(leaf, device->uuid, ptr, BTRFS_UUID_SIZE);
1601
1602         return 0;
1603 }
1604
1605 static int open_seed_devices(struct btrfs_root *root, u8 *fsid)
1606 {
1607         struct btrfs_fs_devices *fs_devices;
1608         int ret;
1609
1610         fs_devices = root->fs_info->fs_devices->seed;
1611         while (fs_devices) {
1612                 if (!memcmp(fs_devices->fsid, fsid, BTRFS_UUID_SIZE)) {
1613                         ret = 0;
1614                         goto out;
1615                 }
1616                 fs_devices = fs_devices->seed;
1617         }
1618
1619         fs_devices = find_fsid(fsid);
1620         if (!fs_devices) {
1621                 ret = -ENOENT;
1622                 goto out;
1623         }
1624
1625         ret = btrfs_open_devices(fs_devices, O_RDONLY);
1626         if (ret)
1627                 goto out;
1628
1629         fs_devices->seed = root->fs_info->fs_devices->seed;
1630         root->fs_info->fs_devices->seed = fs_devices;
1631 out:
1632         return ret;
1633 }
1634
1635 static int read_one_dev(struct btrfs_root *root,
1636                         struct extent_buffer *leaf,
1637                         struct btrfs_dev_item *dev_item)
1638 {
1639         struct btrfs_device *device;
1640         u64 devid;
1641         int ret = 0;
1642         u8 fs_uuid[BTRFS_UUID_SIZE];
1643         u8 dev_uuid[BTRFS_UUID_SIZE];
1644
1645         devid = btrfs_device_id(leaf, dev_item);
1646         read_extent_buffer(leaf, dev_uuid,
1647                            (unsigned long)btrfs_device_uuid(dev_item),
1648                            BTRFS_UUID_SIZE);
1649         read_extent_buffer(leaf, fs_uuid,
1650                            (unsigned long)btrfs_device_fsid(dev_item),
1651                            BTRFS_UUID_SIZE);
1652
1653         if (memcmp(fs_uuid, root->fs_info->fsid, BTRFS_UUID_SIZE)) {
1654                 ret = open_seed_devices(root, fs_uuid);
1655                 if (ret)
1656                         return ret;
1657         }
1658
1659         device = btrfs_find_device(root, devid, dev_uuid, fs_uuid);
1660         if (!device) {
1661                 printk("warning devid %llu not found already\n",
1662                         (unsigned long long)devid);
1663                 device = kzalloc(sizeof(*device), GFP_NOFS);
1664                 if (!device)
1665                         return -ENOMEM;
1666                 device->fd = -1;
1667                 list_add(&device->dev_list,
1668                          &root->fs_info->fs_devices->devices);
1669         }
1670
1671         fill_device_from_item(leaf, dev_item, device);
1672         device->dev_root = root->fs_info->dev_root;
1673         return ret;
1674 }
1675
1676 int btrfs_read_sys_array(struct btrfs_root *root)
1677 {
1678         struct btrfs_super_block *super_copy = root->fs_info->super_copy;
1679         struct extent_buffer *sb;
1680         struct btrfs_disk_key *disk_key;
1681         struct btrfs_chunk *chunk;
1682         struct btrfs_key key;
1683         u32 num_stripes;
1684         u32 len = 0;
1685         u8 *ptr;
1686         u8 *array_end;
1687         int ret = 0;
1688
1689         sb = btrfs_find_create_tree_block(root, BTRFS_SUPER_INFO_OFFSET,
1690                                           BTRFS_SUPER_INFO_SIZE);
1691         if (!sb)
1692                 return -ENOMEM;
1693         btrfs_set_buffer_uptodate(sb);
1694         write_extent_buffer(sb, super_copy, 0, sizeof(*super_copy));
1695         array_end = ((u8 *)super_copy->sys_chunk_array) +
1696                     btrfs_super_sys_array_size(super_copy);
1697
1698         /*
1699          * we do this loop twice, once for the device items and
1700          * once for all of the chunks.  This way there are device
1701          * structs filled in for every chunk
1702          */
1703         ptr = super_copy->sys_chunk_array;
1704
1705         while (ptr < array_end) {
1706                 disk_key = (struct btrfs_disk_key *)ptr;
1707                 btrfs_disk_key_to_cpu(&key, disk_key);
1708
1709                 len = sizeof(*disk_key);
1710                 ptr += len;
1711
1712                 if (key.type == BTRFS_CHUNK_ITEM_KEY) {
1713                         chunk = (struct btrfs_chunk *)(ptr - (u8 *)super_copy);
1714                         ret = read_one_chunk(root, &key, sb, chunk);
1715                         if (ret)
1716                                 break;
1717                         num_stripes = btrfs_chunk_num_stripes(sb, chunk);
1718                         len = btrfs_chunk_item_size(num_stripes);
1719                 } else {
1720                         BUG();
1721                 }
1722                 ptr += len;
1723         }
1724         free_extent_buffer(sb);
1725         return ret;
1726 }
1727
1728 int btrfs_read_chunk_tree(struct btrfs_root *root)
1729 {
1730         struct btrfs_path *path;
1731         struct extent_buffer *leaf;
1732         struct btrfs_key key;
1733         struct btrfs_key found_key;
1734         int ret;
1735         int slot;
1736
1737         root = root->fs_info->chunk_root;
1738
1739         path = btrfs_alloc_path();
1740         if (!path)
1741                 return -ENOMEM;
1742
1743         /*
1744          * Read all device items, and then all the chunk items. All
1745          * device items are found before any chunk item (their object id
1746          * is smaller than the lowest possible object id for a chunk
1747          * item - BTRFS_FIRST_CHUNK_TREE_OBJECTID).
1748          */
1749         key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
1750         key.offset = 0;
1751         key.type = 0;
1752         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1753         if (ret < 0)
1754                 goto error;
1755         while(1) {
1756                 leaf = path->nodes[0];
1757                 slot = path->slots[0];
1758                 if (slot >= btrfs_header_nritems(leaf)) {
1759                         ret = btrfs_next_leaf(root, path);
1760                         if (ret == 0)
1761                                 continue;
1762                         if (ret < 0)
1763                                 goto error;
1764                         break;
1765                 }
1766                 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1767                 if (found_key.type == BTRFS_DEV_ITEM_KEY) {
1768                         struct btrfs_dev_item *dev_item;
1769                         dev_item = btrfs_item_ptr(leaf, slot,
1770                                                   struct btrfs_dev_item);
1771                         ret = read_one_dev(root, leaf, dev_item);
1772                         BUG_ON(ret);
1773                 } else if (found_key.type == BTRFS_CHUNK_ITEM_KEY) {
1774                         struct btrfs_chunk *chunk;
1775                         chunk = btrfs_item_ptr(leaf, slot, struct btrfs_chunk);
1776                         ret = read_one_chunk(root, &found_key, leaf, chunk);
1777                         BUG_ON(ret);
1778                 }
1779                 path->slots[0]++;
1780         }
1781
1782         ret = 0;
1783 error:
1784         btrfs_free_path(path);
1785         return ret;
1786 }
1787
1788 struct list_head *btrfs_scanned_uuids(void)
1789 {
1790         return &fs_uuids;
1791 }
1792
1793 static int rmw_eb(struct btrfs_fs_info *info,
1794                   struct extent_buffer *eb, struct extent_buffer *orig_eb)
1795 {
1796         int ret;
1797         unsigned long orig_off = 0;
1798         unsigned long dest_off = 0;
1799         unsigned long copy_len = eb->len;
1800
1801         ret = read_whole_eb(info, eb, 0);
1802         if (ret)
1803                 return ret;
1804
1805         if (eb->start + eb->len <= orig_eb->start ||
1806             eb->start >= orig_eb->start + orig_eb->len)
1807                 return 0;
1808         /*
1809          * | ----- orig_eb ------- |
1810          *         | ----- stripe -------  |
1811          *         | ----- orig_eb ------- |
1812          *              | ----- orig_eb ------- |
1813          */
1814         if (eb->start > orig_eb->start)
1815                 orig_off = eb->start - orig_eb->start;
1816         if (orig_eb->start > eb->start)
1817                 dest_off = orig_eb->start - eb->start;
1818
1819         if (copy_len > orig_eb->len - orig_off)
1820                 copy_len = orig_eb->len - orig_off;
1821         if (copy_len > eb->len - dest_off)
1822                 copy_len = eb->len - dest_off;
1823
1824         memcpy(eb->data + dest_off, orig_eb->data + orig_off, copy_len);
1825         return 0;
1826 }
1827
1828 static void split_eb_for_raid56(struct btrfs_fs_info *info,
1829                                 struct extent_buffer *orig_eb,
1830                                struct extent_buffer **ebs,
1831                                u64 stripe_len, u64 *raid_map,
1832                                int num_stripes)
1833 {
1834         struct extent_buffer *eb;
1835         u64 start = orig_eb->start;
1836         u64 this_eb_start;
1837         int i;
1838         int ret;
1839
1840         for (i = 0; i < num_stripes; i++) {
1841                 if (raid_map[i] >= BTRFS_RAID5_P_STRIPE)
1842                         break;
1843
1844                 eb = malloc(sizeof(struct extent_buffer) + stripe_len);
1845                 if (!eb)
1846                         BUG();
1847                 memset(eb, 0, sizeof(struct extent_buffer) + stripe_len);
1848
1849                 eb->start = raid_map[i];
1850                 eb->len = stripe_len;
1851                 eb->refs = 1;
1852                 eb->flags = 0;
1853                 eb->fd = -1;
1854                 eb->dev_bytenr = (u64)-1;
1855
1856                 this_eb_start = raid_map[i];
1857
1858                 if (start > this_eb_start ||
1859                     start + orig_eb->len < this_eb_start + stripe_len) {
1860                         ret = rmw_eb(info, eb, orig_eb);
1861                         BUG_ON(ret);
1862                 } else {
1863                         memcpy(eb->data, orig_eb->data + eb->start - start, stripe_len);
1864                 }
1865                 ebs[i] = eb;
1866         }
1867 }
1868
1869 int write_raid56_with_parity(struct btrfs_fs_info *info,
1870                              struct extent_buffer *eb,
1871                              struct btrfs_multi_bio *multi,
1872                              u64 stripe_len, u64 *raid_map)
1873 {
1874         struct extent_buffer **ebs, *p_eb = NULL, *q_eb = NULL;
1875         int i;
1876         int j;
1877         int ret;
1878         int alloc_size = eb->len;
1879
1880         ebs = kmalloc(sizeof(*ebs) * multi->num_stripes, GFP_NOFS);
1881         BUG_ON(!ebs);
1882
1883         if (stripe_len > alloc_size)
1884                 alloc_size = stripe_len;
1885
1886         split_eb_for_raid56(info, eb, ebs, stripe_len, raid_map,
1887                             multi->num_stripes);
1888
1889         for (i = 0; i < multi->num_stripes; i++) {
1890                 struct extent_buffer *new_eb;
1891                 if (raid_map[i] < BTRFS_RAID5_P_STRIPE) {
1892                         ebs[i]->dev_bytenr = multi->stripes[i].physical;
1893                         ebs[i]->fd = multi->stripes[i].dev->fd;
1894                         multi->stripes[i].dev->total_ios++;
1895                         BUG_ON(ebs[i]->start != raid_map[i]);
1896                         continue;
1897                 }
1898                 new_eb = kmalloc(sizeof(*eb) + alloc_size, GFP_NOFS);
1899                 BUG_ON(!new_eb);
1900                 new_eb->dev_bytenr = multi->stripes[i].physical;
1901                 new_eb->fd = multi->stripes[i].dev->fd;
1902                 multi->stripes[i].dev->total_ios++;
1903                 new_eb->len = stripe_len;
1904
1905                 if (raid_map[i] == BTRFS_RAID5_P_STRIPE)
1906                         p_eb = new_eb;
1907                 else if (raid_map[i] == BTRFS_RAID6_Q_STRIPE)
1908                         q_eb = new_eb;
1909         }
1910         if (q_eb) {
1911                 void **pointers;
1912
1913                 pointers = kmalloc(sizeof(*pointers) * multi->num_stripes,
1914                                    GFP_NOFS);
1915                 BUG_ON(!pointers);
1916
1917                 ebs[multi->num_stripes - 2] = p_eb;
1918                 ebs[multi->num_stripes - 1] = q_eb;
1919
1920                 for (i = 0; i < multi->num_stripes; i++)
1921                         pointers[i] = ebs[i]->data;
1922
1923                 raid6_gen_syndrome(multi->num_stripes, stripe_len, pointers);
1924                 kfree(pointers);
1925         } else {
1926                 ebs[multi->num_stripes - 1] = p_eb;
1927                 memcpy(p_eb->data, ebs[0]->data, stripe_len);
1928                 for (j = 1; j < multi->num_stripes - 1; j++) {
1929                         for (i = 0; i < stripe_len; i += sizeof(unsigned long)) {
1930                                 *(unsigned long *)(p_eb->data + i) ^=
1931                                         *(unsigned long *)(ebs[j]->data + i);
1932                         }
1933                 }
1934         }
1935
1936         for (i = 0; i < multi->num_stripes; i++) {
1937                 ret = write_extent_to_disk(ebs[i]);
1938                 BUG_ON(ret);
1939                 if (ebs[i] != eb)
1940                         kfree(ebs[i]);
1941         }
1942
1943         kfree(ebs);
1944
1945         return 0;
1946 }