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