fs/btrfs/disk-io.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
  19 #include <linux/version.h>
  20 #include <linux/fs.h>
  21 #include <linux/blkdev.h>
  22 #include <linux/scatterlist.h>
  23 #include <linux/swap.h>
  24 #include <linux/radix-tree.h>
  25 #include <linux/writeback.h>
  26 #include <linux/buffer_head.h> // for block_sync_page
  27 #include <linux/workqueue.h>
  28 #include <linux/kthread.h>
  29 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,20)
  30 # include <linux/freezer.h>
  31 #else
  32 # include <linux/sched.h>
  33 #endif
  34 #include "crc32c.h"
  35 #include "ctree.h"
  36 #include "disk-io.h"
  37 #include "transaction.h"
  38 #include "btrfs_inode.h"
  39 #include "volumes.h"
  40 #include "print-tree.h"
  41 #include "async-thread.h"
  42 #include "locking.h"
  43 #include "ref-cache.h"
  44
  45 #if 0
  46 static int check_tree_block(struct btrfs_root *root, struct extent_buffer *buf)
  47 {
  48         if (extent_buffer_blocknr(buf) != btrfs_header_blocknr(buf)) {
  49                 printk(KERN_CRIT "buf blocknr(buf) is %llu, header is %llu\n",
  50                        (unsigned long long)extent_buffer_blocknr(buf),
  51                        (unsigned long long)btrfs_header_blocknr(buf));
  52                 return 1;
  53         }
  54         return 0;
  55 }
  56 #endif
  57
  58 static struct extent_io_ops btree_extent_io_ops;
  59 static void end_workqueue_fn(struct btrfs_work *work);
  60
  61 struct end_io_wq {
  62         struct bio *bio;
  63         bio_end_io_t *end_io;
  64         void *private;
  65         struct btrfs_fs_info *info;
  66         int error;
  67         int metadata;
  68         struct list_head list;
  69         struct btrfs_work work;
  70 };
  71
  72 struct async_submit_bio {
  73         struct inode *inode;
  74         struct bio *bio;
  75         struct list_head list;
  76         extent_submit_bio_hook_t *submit_bio_hook;
  77         int rw;
  78         int mirror_num;
  79         struct btrfs_work work;
  80 };
  81
  82 struct extent_map *btree_get_extent(struct inode *inode, struct page *page,
  83                                     size_t page_offset, u64 start, u64 len,
  84                                     int create)
  85 {
  86         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
  87         struct extent_map *em;
  88         int ret;
  89
  90         spin_lock(&em_tree->lock);
  91         em = lookup_extent_mapping(em_tree, start, len);
  92         if (em) {
  93                 em->bdev =
  94                         BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
  95                 spin_unlock(&em_tree->lock);
  96                 goto out;
  97         }
  98         spin_unlock(&em_tree->lock);
  99
 100         em = alloc_extent_map(GFP_NOFS);
 101         if (!em) {
 102                 em = ERR_PTR(-ENOMEM);
 103                 goto out;
 104         }
 105         em->start = 0;
 106         em->len = (u64)-1;
 107         em->block_start = 0;
 108         em->bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
 109
 110         spin_lock(&em_tree->lock);
 111         ret = add_extent_mapping(em_tree, em);
 112         if (ret == -EEXIST) {
 113                 u64 failed_start = em->start;
 114                 u64 failed_len = em->len;
 115
 116                 printk("failed to insert %Lu %Lu -> %Lu into tree\n",
 117                        em->start, em->len, em->block_start);
 118                 free_extent_map(em);
 119                 em = lookup_extent_mapping(em_tree, start, len);
 120                 if (em) {
 121                         printk("after failing, found %Lu %Lu %Lu\n",
 122                                em->start, em->len, em->block_start);
 123                         ret = 0;
 124                 } else {
 125                         em = lookup_extent_mapping(em_tree, failed_start,
 126                                                    failed_len);
 127                         if (em) {
 128                                 printk("double failure lookup gives us "
 129                                        "%Lu %Lu -> %Lu\n", em->start,
 130                                        em->len, em->block_start);
 131                                 free_extent_map(em);
 132                         }
 133                         ret = -EIO;
 134                 }
 135         } else if (ret) {
 136                 free_extent_map(em);
 137                 em = NULL;
 138         }
 139         spin_unlock(&em_tree->lock);
 140
 141         if (ret)
 142                 em = ERR_PTR(ret);
 143 out:
 144         return em;
 145 }
 146
 147 u32 btrfs_csum_data(struct btrfs_root *root, char *data, u32 seed, size_t len)
 148 {
 149         return btrfs_crc32c(seed, data, len);
 150 }
 151
 152 void btrfs_csum_final(u32 crc, char *result)
 153 {
 154         *(__le32 *)result = ~cpu_to_le32(crc);
 155 }
 156
 157 static int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf,
 158                            int verify)
 159 {
 160         char result[BTRFS_CRC32_SIZE];
 161         unsigned long len;
 162         unsigned long cur_len;
 163         unsigned long offset = BTRFS_CSUM_SIZE;
 164         char *map_token = NULL;
 165         char *kaddr;
 166         unsigned long map_start;
 167         unsigned long map_len;
 168         int err;
 169         u32 crc = ~(u32)0;
 170
 171         len = buf->len - offset;
 172         while(len > 0) {
 173                 err = map_private_extent_buffer(buf, offset, 32,
 174                                         &map_token, &kaddr,
 175                                         &map_start, &map_len, KM_USER0);
 176                 if (err) {
 177                         printk("failed to map extent buffer! %lu\n",
 178                                offset);
 179                         return 1;
 180                 }
 181                 cur_len = min(len, map_len - (offset - map_start));
 182                 crc = btrfs_csum_data(root, kaddr + offset - map_start,
 183                                       crc, cur_len);
 184                 len -= cur_len;
 185                 offset += cur_len;
 186                 unmap_extent_buffer(buf, map_token, KM_USER0);
 187         }
 188         btrfs_csum_final(crc, result);
 189
 190         if (verify) {
 191                 /* FIXME, this is not good */
 192                 if (memcmp_extent_buffer(buf, result, 0, BTRFS_CRC32_SIZE)) {
 193                         u32 val;
 194                         u32 found = 0;
 195                         memcpy(&found, result, BTRFS_CRC32_SIZE);
 196
 197                         read_extent_buffer(buf, &val, 0, BTRFS_CRC32_SIZE);
 198                         printk("btrfs: %s checksum verify failed on %llu "
 199                                "wanted %X found %X level %d\n",
 200                                root->fs_info->sb->s_id,
 201                                buf->start, val, found, btrfs_header_level(buf));
 202                         return 1;
 203                 }
 204         } else {
 205                 write_extent_buffer(buf, result, 0, BTRFS_CRC32_SIZE);
 206         }
 207         return 0;
 208 }
 209
 210 static int verify_parent_transid(struct extent_io_tree *io_tree,
 211                                  struct extent_buffer *eb, u64 parent_transid)
 212 {
 213         int ret;
 214
 215         if (!parent_transid || btrfs_header_generation(eb) == parent_transid)
 216                 return 0;
 217
 218         lock_extent(io_tree, eb->start, eb->start + eb->len - 1, GFP_NOFS);
 219         if (extent_buffer_uptodate(io_tree, eb) &&
 220             btrfs_header_generation(eb) == parent_transid) {
 221                 ret = 0;
 222                 goto out;
 223         }
 224         printk("parent transid verify failed on %llu wanted %llu found %llu\n",
 225                (unsigned long long)eb->start,
 226                (unsigned long long)parent_transid,
 227                (unsigned long long)btrfs_header_generation(eb));
 228         ret = 1;
 229         clear_extent_buffer_uptodate(io_tree, eb);
 230 out:
 231         unlock_extent(io_tree, eb->start, eb->start + eb->len - 1,
 232                       GFP_NOFS);
 233         return ret;
 234
 235 }
 236
 237 static int btree_read_extent_buffer_pages(struct btrfs_root *root,
 238                                           struct extent_buffer *eb,
 239                                           u64 start, u64 parent_transid)
 240 {
 241         struct extent_io_tree *io_tree;
 242         int ret;
 243         int num_copies = 0;
 244         int mirror_num = 0;
 245
 246         io_tree = &BTRFS_I(root->fs_info->btree_inode)->io_tree;
 247         while (1) {
 248                 ret = read_extent_buffer_pages(io_tree, eb, start, 1,
 249                                                btree_get_extent, mirror_num);
 250                 if (!ret &&
 251                     !verify_parent_transid(io_tree, eb, parent_transid))
 252                         return ret;
 253
 254                 num_copies = btrfs_num_copies(&root->fs_info->mapping_tree,
 255                                               eb->start, eb->len);
 256                 if (num_copies == 1)
 257                         return ret;
 258
 259                 mirror_num++;
 260                 if (mirror_num > num_copies)
 261                         return ret;
 262         }
 263         return -EIO;
 264 }
 265
 266 int csum_dirty_buffer(struct btrfs_root *root, struct page *page)
 267 {
 268         struct extent_io_tree *tree;
 269         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
 270         u64 found_start;
 271         int found_level;
 272         unsigned long len;
 273         struct extent_buffer *eb;
 274         int ret;
 275
 276         tree = &BTRFS_I(page->mapping->host)->io_tree;
 277
 278         if (page->private == EXTENT_PAGE_PRIVATE)
 279                 goto out;
 280         if (!page->private)
 281                 goto out;
 282         len = page->private >> 2;
 283         if (len == 0) {
 284                 WARN_ON(1);
 285         }
 286         eb = alloc_extent_buffer(tree, start, len, page, GFP_NOFS);
 287         ret = btree_read_extent_buffer_pages(root, eb, start + PAGE_CACHE_SIZE,
 288                                              btrfs_header_generation(eb));
 289         BUG_ON(ret);
 290         found_start = btrfs_header_bytenr(eb);
 291         if (found_start != start) {
 292                 printk("warning: eb start incorrect %Lu buffer %Lu len %lu\n",
 293                        start, found_start, len);
 294                 WARN_ON(1);
 295                 goto err;
 296         }
 297         if (eb->first_page != page) {
 298                 printk("bad first page %lu %lu\n", eb->first_page->index,
 299                        page->index);
 300                 WARN_ON(1);
 301                 goto err;
 302         }
 303         if (!PageUptodate(page)) {
 304                 printk("csum not up to date page %lu\n", page->index);
 305                 WARN_ON(1);
 306                 goto err;
 307         }
 308         found_level = btrfs_header_level(eb);
 309         spin_lock(&root->fs_info->hash_lock);
 310         btrfs_set_header_flag(eb, BTRFS_HEADER_FLAG_WRITTEN);
 311         spin_unlock(&root->fs_info->hash_lock);
 312         csum_tree_block(root, eb, 0);
 313 err:
 314         free_extent_buffer(eb);
 315 out:
 316         return 0;
 317 }
 318
 319 static int btree_writepage_io_hook(struct page *page, u64 start, u64 end)
 320 {
 321         struct btrfs_root *root = BTRFS_I(page->mapping->host)->root;
 322
 323         csum_dirty_buffer(root, page);
 324         return 0;
 325 }
 326
 327 int btree_readpage_end_io_hook(struct page *page, u64 start, u64 end,
 328                                struct extent_state *state)
 329 {
 330         struct extent_io_tree *tree;
 331         u64 found_start;
 332         int found_level;
 333         unsigned long len;
 334         struct extent_buffer *eb;
 335         struct btrfs_root *root = BTRFS_I(page->mapping->host)->root;
 336         int ret = 0;
 337
 338         tree = &BTRFS_I(page->mapping->host)->io_tree;
 339         if (page->private == EXTENT_PAGE_PRIVATE)
 340                 goto out;
 341         if (!page->private)
 342                 goto out;
 343         len = page->private >> 2;
 344         if (len == 0) {
 345                 WARN_ON(1);
 346         }
 347         eb = alloc_extent_buffer(tree, start, len, page, GFP_NOFS);
 348
 349         found_start = btrfs_header_bytenr(eb);
 350         if (found_start != start) {
 351                 ret = -EIO;
 352                 goto err;
 353         }
 354         if (eb->first_page != page) {
 355                 printk("bad first page %lu %lu\n", eb->first_page->index,
 356                        page->index);
 357                 WARN_ON(1);
 358                 ret = -EIO;
 359                 goto err;
 360         }
 361         if (memcmp_extent_buffer(eb, root->fs_info->fsid,
 362                                  (unsigned long)btrfs_header_fsid(eb),
 363                                  BTRFS_FSID_SIZE)) {
 364                 printk("bad fsid on block %Lu\n", eb->start);
 365                 ret = -EIO;
 366                 goto err;
 367         }
 368         found_level = btrfs_header_level(eb);
 369
 370         ret = csum_tree_block(root, eb, 1);
 371         if (ret)
 372                 ret = -EIO;
 373
 374         end = min_t(u64, eb->len, PAGE_CACHE_SIZE);
 375         end = eb->start + end - 1;
 376 err:
 377         free_extent_buffer(eb);
 378 out:
 379         return ret;
 380 }
 381
 382 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,23)
 383 static void end_workqueue_bio(struct bio *bio, int err)
 384 #else
 385 static int end_workqueue_bio(struct bio *bio,
 386                                    unsigned int bytes_done, int err)
 387 #endif
 388 {
 389         struct end_io_wq *end_io_wq = bio->bi_private;
 390         struct btrfs_fs_info *fs_info;
 391
 392 #if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
 393         if (bio->bi_size)
 394                 return 1;
 395 #endif
 396
 397         fs_info = end_io_wq->info;
 398         end_io_wq->error = err;
 399         end_io_wq->work.func = end_workqueue_fn;
 400         end_io_wq->work.flags = 0;
 401         if (bio->bi_rw & (1 << BIO_RW))
 402                 btrfs_queue_worker(&fs_info->endio_write_workers,
 403                                    &end_io_wq->work);
 404         else
 405                 btrfs_queue_worker(&fs_info->endio_workers, &end_io_wq->work);
 406
 407 #if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
 408         return 0;
 409 #endif
 410 }
 411
 412 int btrfs_bio_wq_end_io(struct btrfs_fs_info *info, struct bio *bio,
 413                         int metadata)
 414 {
 415         struct end_io_wq *end_io_wq;
 416         end_io_wq = kmalloc(sizeof(*end_io_wq), GFP_NOFS);
 417         if (!end_io_wq)
 418                 return -ENOMEM;
 419
 420         end_io_wq->private = bio->bi_private;
 421         end_io_wq->end_io = bio->bi_end_io;
 422         end_io_wq->info = info;
 423         end_io_wq->error = 0;
 424         end_io_wq->bio = bio;
 425         end_io_wq->metadata = metadata;
 426
 427         bio->bi_private = end_io_wq;
 428         bio->bi_end_io = end_workqueue_bio;
 429         return 0;
 430 }
 431
 432 static unsigned long async_submit_limit(struct btrfs_fs_info *info)
 433 {
 434         unsigned long limit = min_t(unsigned long,
 435                                     info->workers.max_workers,
 436                                     info->fs_devices->open_devices);
 437         return 256 * limit;
 438 }
 439
 440 int btrfs_congested_async(struct btrfs_fs_info *info, int iodone)
 441 {
 442         return atomic_read(&info->nr_async_bios) > async_submit_limit(info);
 443 }
 444
 445 static void run_one_async_submit(struct btrfs_work *work)
 446 {
 447         struct btrfs_fs_info *fs_info;
 448         struct async_submit_bio *async;
 449         int limit;
 450
 451         async = container_of(work, struct  async_submit_bio, work);
 452         fs_info = BTRFS_I(async->inode)->root->fs_info;
 453
 454         limit = async_submit_limit(fs_info);
 455         limit = limit * 2 / 3;
 456
 457         atomic_dec(&fs_info->nr_async_submits);
 458
 459         if (atomic_read(&fs_info->nr_async_submits) < limit)
 460                 wake_up(&fs_info->async_submit_wait);
 461
 462         async->submit_bio_hook(async->inode, async->rw, async->bio,
 463                                async->mirror_num);
 464         kfree(async);
 465 }
 466
 467 int btrfs_wq_submit_bio(struct btrfs_fs_info *fs_info, struct inode *inode,
 468                         int rw, struct bio *bio, int mirror_num,
 469                         extent_submit_bio_hook_t *submit_bio_hook)
 470 {
 471         struct async_submit_bio *async;
 472         int limit = async_submit_limit(fs_info);
 473
 474         async = kmalloc(sizeof(*async), GFP_NOFS);
 475         if (!async)
 476                 return -ENOMEM;
 477
 478         async->inode = inode;
 479         async->rw = rw;
 480         async->bio = bio;
 481         async->mirror_num = mirror_num;
 482         async->submit_bio_hook = submit_bio_hook;
 483         async->work.func = run_one_async_submit;
 484         async->work.flags = 0;
 485         atomic_inc(&fs_info->nr_async_submits);
 486         btrfs_queue_worker(&fs_info->workers, &async->work);
 487
 488         wait_event_timeout(fs_info->async_submit_wait,
 489                            (atomic_read(&fs_info->nr_async_submits) < limit),
 490                            HZ/10);
 491         return 0;
 492 }
 493
 494 static int __btree_submit_bio_hook(struct inode *inode, int rw, struct bio *bio,
 495                                  int mirror_num)
 496 {
 497         struct btrfs_root *root = BTRFS_I(inode)->root;
 498         u64 offset;
 499         int ret;
 500
 501         offset = bio->bi_sector << 9;
 502
 503         /*
 504          * when we're called for a write, we're already in the async
 505          * submission context.  Just jump into btrfs_map_bio
 506          */
 507         if (rw & (1 << BIO_RW)) {
 508                 return btrfs_map_bio(BTRFS_I(inode)->root, rw, bio,
 509                                      mirror_num, 1);
 510         }
 511
 512         /*
 513          * called for a read, do the setup so that checksum validation
 514          * can happen in the async kernel threads
 515          */
 516         ret = btrfs_bio_wq_end_io(root->fs_info, bio, 1);
 517         BUG_ON(ret);
 518
 519         return btrfs_map_bio(BTRFS_I(inode)->root, rw, bio, mirror_num, 1);
 520 }
 521
 522 static int btree_submit_bio_hook(struct inode *inode, int rw, struct bio *bio,
 523                                  int mirror_num)
 524 {
 525         /*
 526          * kthread helpers are used to submit writes so that checksumming
 527          * can happen in parallel across all CPUs
 528          */
 529         if (!(rw & (1 << BIO_RW))) {
 530                 return __btree_submit_bio_hook(inode, rw, bio, mirror_num);
 531         }
 532         return btrfs_wq_submit_bio(BTRFS_I(inode)->root->fs_info,
 533                                    inode, rw, bio, mirror_num,
 534                                    __btree_submit_bio_hook);
 535 }
 536
 537 static int btree_writepage(struct page *page, struct writeback_control *wbc)
 538 {
 539         struct extent_io_tree *tree;
 540         tree = &BTRFS_I(page->mapping->host)->io_tree;
 541
 542         if (current->flags & PF_MEMALLOC) {
 543                 redirty_page_for_writepage(wbc, page);
 544                 unlock_page(page);
 545                 return 0;
 546         }
 547         return extent_write_full_page(tree, page, btree_get_extent, wbc);
 548 }
 549
 550 static int btree_writepages(struct address_space *mapping,
 551                             struct writeback_control *wbc)
 552 {
 553         struct extent_io_tree *tree;
 554         tree = &BTRFS_I(mapping->host)->io_tree;
 555         if (wbc->sync_mode == WB_SYNC_NONE) {
 556                 u64 num_dirty;
 557                 u64 start = 0;
 558                 unsigned long thresh = 8 * 1024 * 1024;
 559
 560                 if (wbc->for_kupdate)
 561                         return 0;
 562
 563                 num_dirty = count_range_bits(tree, &start, (u64)-1,
 564                                              thresh, EXTENT_DIRTY);
 565                 if (num_dirty < thresh) {
 566                         return 0;
 567                 }
 568         }
 569         return extent_writepages(tree, mapping, btree_get_extent, wbc);
 570 }
 571
 572 int btree_readpage(struct file *file, struct page *page)
 573 {
 574         struct extent_io_tree *tree;
 575         tree = &BTRFS_I(page->mapping->host)->io_tree;
 576         return extent_read_full_page(tree, page, btree_get_extent);
 577 }
 578
 579 static int btree_releasepage(struct page *page, gfp_t gfp_flags)
 580 {
 581         struct extent_io_tree *tree;
 582         struct extent_map_tree *map;
 583         int ret;
 584
 585         tree = &BTRFS_I(page->mapping->host)->io_tree;
 586         map = &BTRFS_I(page->mapping->host)->extent_tree;
 587
 588         ret = try_release_extent_state(map, tree, page, gfp_flags);
 589         if (!ret) {
 590                 return 0;
 591         }
 592
 593         ret = try_release_extent_buffer(tree, page);
 594         if (ret == 1) {
 595                 ClearPagePrivate(page);
 596                 set_page_private(page, 0);
 597                 page_cache_release(page);
 598         }
 599
 600         return ret;
 601 }
 602
 603 static void btree_invalidatepage(struct page *page, unsigned long offset)
 604 {
 605         struct extent_io_tree *tree;
 606         tree = &BTRFS_I(page->mapping->host)->io_tree;
 607         extent_invalidatepage(tree, page, offset);
 608         btree_releasepage(page, GFP_NOFS);
 609         if (PagePrivate(page)) {
 610                 printk("warning page private not zero on page %Lu\n",
 611                        page_offset(page));
 612                 ClearPagePrivate(page);
 613                 set_page_private(page, 0);
 614                 page_cache_release(page);
 615         }
 616 }
 617
 618 #if 0
 619 static int btree_writepage(struct page *page, struct writeback_control *wbc)
 620 {
 621         struct buffer_head *bh;
 622         struct btrfs_root *root = BTRFS_I(page->mapping->host)->root;
 623         struct buffer_head *head;
 624         if (!page_has_buffers(page)) {
 625                 create_empty_buffers(page, root->fs_info->sb->s_blocksize,
 626                                         (1 << BH_Dirty)|(1 << BH_Uptodate));
 627         }
 628         head = page_buffers(page);
 629         bh = head;
 630         do {
 631                 if (buffer_dirty(bh))
 632                         csum_tree_block(root, bh, 0);
 633                 bh = bh->b_this_page;
 634         } while (bh != head);
 635         return block_write_full_page(page, btree_get_block, wbc);
 636 }
 637 #endif
 638
 639 static struct address_space_operations btree_aops = {
 640         .readpage       = btree_readpage,
 641         .writepage      = btree_writepage,
 642         .writepages     = btree_writepages,
 643         .releasepage    = btree_releasepage,
 644         .invalidatepage = btree_invalidatepage,
 645         .sync_page      = block_sync_page,
 646 };
 647
 648 int readahead_tree_block(struct btrfs_root *root, u64 bytenr, u32 blocksize,
 649                          u64 parent_transid)
 650 {
 651         struct extent_buffer *buf = NULL;
 652         struct inode *btree_inode = root->fs_info->btree_inode;
 653         int ret = 0;
 654
 655         buf = btrfs_find_create_tree_block(root, bytenr, blocksize);
 656         if (!buf)
 657                 return 0;
 658         read_extent_buffer_pages(&BTRFS_I(btree_inode)->io_tree,
 659                                  buf, 0, 0, btree_get_extent, 0);
 660         free_extent_buffer(buf);
 661         return ret;
 662 }
 663
 664 struct extent_buffer *btrfs_find_tree_block(struct btrfs_root *root,
 665                                             u64 bytenr, u32 blocksize)
 666 {
 667         struct inode *btree_inode = root->fs_info->btree_inode;
 668         struct extent_buffer *eb;
 669         eb = find_extent_buffer(&BTRFS_I(btree_inode)->io_tree,
 670                                 bytenr, blocksize, GFP_NOFS);
 671         return eb;
 672 }
 673
 674 struct extent_buffer *btrfs_find_create_tree_block(struct btrfs_root *root,
 675                                                  u64 bytenr, u32 blocksize)
 676 {
 677         struct inode *btree_inode = root->fs_info->btree_inode;
 678         struct extent_buffer *eb;
 679
 680         eb = alloc_extent_buffer(&BTRFS_I(btree_inode)->io_tree,
 681                                  bytenr, blocksize, NULL, GFP_NOFS);
 682         return eb;
 683 }
 684
 685
 686 struct extent_buffer *read_tree_block(struct btrfs_root *root, u64 bytenr,
 687                                       u32 blocksize, u64 parent_transid)
 688 {
 689         struct extent_buffer *buf = NULL;
 690         struct inode *btree_inode = root->fs_info->btree_inode;
 691         struct extent_io_tree *io_tree;
 692         int ret;
 693
 694         io_tree = &BTRFS_I(btree_inode)->io_tree;
 695
 696         buf = btrfs_find_create_tree_block(root, bytenr, blocksize);
 697         if (!buf)
 698                 return NULL;
 699
 700         ret = btree_read_extent_buffer_pages(root, buf, 0, parent_transid);
 701
 702         if (ret == 0) {
 703                 buf->flags |= EXTENT_UPTODATE;
 704         }
 705         return buf;
 706
 707 }
 708
 709 int clean_tree_block(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 710                      struct extent_buffer *buf)
 711 {
 712         struct inode *btree_inode = root->fs_info->btree_inode;
 713         if (btrfs_header_generation(buf) ==
 714             root->fs_info->running_transaction->transid) {
 715                 WARN_ON(!btrfs_tree_locked(buf));
 716                 clear_extent_buffer_dirty(&BTRFS_I(btree_inode)->io_tree,
 717                                           buf);
 718         }
 719         return 0;
 720 }
 721
 722 int wait_on_tree_block_writeback(struct btrfs_root *root,
 723                                  struct extent_buffer *buf)
 724 {
 725         struct inode *btree_inode = root->fs_info->btree_inode;
 726         wait_on_extent_buffer_writeback(&BTRFS_I(btree_inode)->io_tree,
 727                                         buf);
 728         return 0;
 729 }
 730
 731 static int __setup_root(u32 nodesize, u32 leafsize, u32 sectorsize,
 732                         u32 stripesize, struct btrfs_root *root,
 733                         struct btrfs_fs_info *fs_info,
 734                         u64 objectid)
 735 {
 736         root->node = NULL;
 737         root->inode = NULL;
 738         root->commit_root = NULL;
 739         root->ref_tree = NULL;
 740         root->sectorsize = sectorsize;
 741         root->nodesize = nodesize;
 742         root->leafsize = leafsize;
 743         root->stripesize = stripesize;
 744         root->ref_cows = 0;
 745         root->track_dirty = 0;
 746
 747         root->fs_info = fs_info;
 748         root->objectid = objectid;
 749         root->last_trans = 0;
 750         root->highest_inode = 0;
 751         root->last_inode_alloc = 0;
 752         root->name = NULL;
 753         root->in_sysfs = 0;
 754
 755         INIT_LIST_HEAD(&root->dirty_list);
 756         INIT_LIST_HEAD(&root->orphan_list);
 757         INIT_LIST_HEAD(&root->dead_list);
 758         spin_lock_init(&root->node_lock);
 759         spin_lock_init(&root->list_lock);
 760         mutex_init(&root->objectid_mutex);
 761
 762         btrfs_leaf_ref_tree_init(&root->ref_tree_struct);
 763         root->ref_tree = &root->ref_tree_struct;
 764
 765         memset(&root->root_key, 0, sizeof(root->root_key));
 766         memset(&root->root_item, 0, sizeof(root->root_item));
 767         memset(&root->defrag_progress, 0, sizeof(root->defrag_progress));
 768         memset(&root->root_kobj, 0, sizeof(root->root_kobj));
 769         root->defrag_trans_start = fs_info->generation;
 770         init_completion(&root->kobj_unregister);
 771         root->defrag_running = 0;
 772         root->defrag_level = 0;
 773         root->root_key.objectid = objectid;
 774         return 0;
 775 }
 776
 777 static int find_and_setup_root(struct btrfs_root *tree_root,
 778                                struct btrfs_fs_info *fs_info,
 779                                u64 objectid,
 780                                struct btrfs_root *root)
 781 {
 782         int ret;
 783         u32 blocksize;
 784
 785         __setup_root(tree_root->nodesize, tree_root->leafsize,
 786                      tree_root->sectorsize, tree_root->stripesize,
 787                      root, fs_info, objectid);
 788         ret = btrfs_find_last_root(tree_root, objectid,
 789                                    &root->root_item, &root->root_key);
 790         BUG_ON(ret);
 791
 792         blocksize = btrfs_level_size(root, btrfs_root_level(&root->root_item));
 793         root->node = read_tree_block(root, btrfs_root_bytenr(&root->root_item),
 794                                      blocksize, 0);
 795         BUG_ON(!root->node);
 796         return 0;
 797 }
 798
 799 struct btrfs_root *btrfs_read_fs_root_no_radix(struct btrfs_fs_info *fs_info,
 800                                                struct btrfs_key *location)
 801 {
 802         struct btrfs_root *root;
 803         struct btrfs_root *tree_root = fs_info->tree_root;
 804         struct btrfs_path *path;
 805         struct extent_buffer *l;
 806         u64 highest_inode;
 807         u32 blocksize;
 808         int ret = 0;
 809
 810         root = kzalloc(sizeof(*root), GFP_NOFS);
 811         if (!root)
 812                 return ERR_PTR(-ENOMEM);
 813         if (location->offset == (u64)-1) {
 814                 ret = find_and_setup_root(tree_root, fs_info,
 815                                           location->objectid, root);
 816                 if (ret) {
 817                         kfree(root);
 818                         return ERR_PTR(ret);
 819                 }
 820                 goto insert;
 821         }
 822
 823         __setup_root(tree_root->nodesize, tree_root->leafsize,
 824                      tree_root->sectorsize, tree_root->stripesize,
 825                      root, fs_info, location->objectid);
 826
 827         path = btrfs_alloc_path();
 828         BUG_ON(!path);
 829         ret = btrfs_search_slot(NULL, tree_root, location, path, 0, 0);
 830         if (ret != 0) {
 831                 if (ret > 0)
 832                         ret = -ENOENT;
 833                 goto out;
 834         }
 835         l = path->nodes[0];
 836         read_extent_buffer(l, &root->root_item,
 837                btrfs_item_ptr_offset(l, path->slots[0]),
 838                sizeof(root->root_item));
 839         memcpy(&root->root_key, location, sizeof(*location));
 840         ret = 0;
 841 out:
 842         btrfs_release_path(root, path);
 843         btrfs_free_path(path);
 844         if (ret) {
 845                 kfree(root);
 846                 return ERR_PTR(ret);
 847         }
 848         blocksize = btrfs_level_size(root, btrfs_root_level(&root->root_item));
 849         root->node = read_tree_block(root, btrfs_root_bytenr(&root->root_item),
 850                                      blocksize, 0);
 851         BUG_ON(!root->node);
 852 insert:
 853         root->ref_cows = 1;
 854         ret = btrfs_find_highest_inode(root, &highest_inode);
 855         if (ret == 0) {
 856                 root->highest_inode = highest_inode;
 857                 root->last_inode_alloc = highest_inode;
 858         }
 859         return root;
 860 }
 861
 862 struct btrfs_root *btrfs_lookup_fs_root(struct btrfs_fs_info *fs_info,
 863                                         u64 root_objectid)
 864 {
 865         struct btrfs_root *root;
 866
 867         if (root_objectid == BTRFS_ROOT_TREE_OBJECTID)
 868                 return fs_info->tree_root;
 869         if (root_objectid == BTRFS_EXTENT_TREE_OBJECTID)
 870                 return fs_info->extent_root;
 871
 872         root = radix_tree_lookup(&fs_info->fs_roots_radix,
 873                                  (unsigned long)root_objectid);
 874         return root;
 875 }
 876
 877 struct btrfs_root *btrfs_read_fs_root_no_name(struct btrfs_fs_info *fs_info,
 878                                               struct btrfs_key *location)
 879 {
 880         struct btrfs_root *root;
 881         int ret;
 882
 883         if (location->objectid == BTRFS_ROOT_TREE_OBJECTID)
 884                 return fs_info->tree_root;
 885         if (location->objectid == BTRFS_EXTENT_TREE_OBJECTID)
 886                 return fs_info->extent_root;
 887         if (location->objectid == BTRFS_CHUNK_TREE_OBJECTID)
 888                 return fs_info->chunk_root;
 889         if (location->objectid == BTRFS_DEV_TREE_OBJECTID)
 890                 return fs_info->dev_root;
 891
 892         root = radix_tree_lookup(&fs_info->fs_roots_radix,
 893                                  (unsigned long)location->objectid);
 894         if (root)
 895                 return root;
 896
 897         root = btrfs_read_fs_root_no_radix(fs_info, location);
 898         if (IS_ERR(root))
 899                 return root;
 900         ret = radix_tree_insert(&fs_info->fs_roots_radix,
 901                                 (unsigned long)root->root_key.objectid,
 902                                 root);
 903         if (ret) {
 904                 free_extent_buffer(root->node);
 905                 kfree(root);
 906                 return ERR_PTR(ret);
 907         }
 908         ret = btrfs_find_dead_roots(fs_info->tree_root,
 909                                     root->root_key.objectid, root);
 910         BUG_ON(ret);
 911
 912         return root;
 913 }
 914
 915 struct btrfs_root *btrfs_read_fs_root(struct btrfs_fs_info *fs_info,
 916                                       struct btrfs_key *location,
 917                                       const char *name, int namelen)
 918 {
 919         struct btrfs_root *root;
 920         int ret;
 921
 922         root = btrfs_read_fs_root_no_name(fs_info, location);
 923         if (!root)
 924                 return NULL;
 925
 926         if (root->in_sysfs)
 927                 return root;
 928
 929         ret = btrfs_set_root_name(root, name, namelen);
 930         if (ret) {
 931                 free_extent_buffer(root->node);
 932                 kfree(root);
 933                 return ERR_PTR(ret);
 934         }
 935
 936         ret = btrfs_sysfs_add_root(root);
 937         if (ret) {
 938                 free_extent_buffer(root->node);
 939                 kfree(root->name);
 940                 kfree(root);
 941                 return ERR_PTR(ret);
 942         }
 943         root->in_sysfs = 1;
 944         return root;
 945 }
 946 #if 0
 947 static int add_hasher(struct btrfs_fs_info *info, char *type) {
 948         struct btrfs_hasher *hasher;
 949
 950         hasher = kmalloc(sizeof(*hasher), GFP_NOFS);
 951         if (!hasher)
 952                 return -ENOMEM;
 953         hasher->hash_tfm = crypto_alloc_hash(type, 0, CRYPTO_ALG_ASYNC);
 954         if (!hasher->hash_tfm) {
 955                 kfree(hasher);
 956                 return -EINVAL;
 957         }
 958         spin_lock(&info->hash_lock);
 959         list_add(&hasher->list, &info->hashers);
 960         spin_unlock(&info->hash_lock);
 961         return 0;
 962 }
 963 #endif
 964
 965 static int btrfs_congested_fn(void *congested_data, int bdi_bits)
 966 {
 967         struct btrfs_fs_info *info = (struct btrfs_fs_info *)congested_data;
 968         int ret = 0;
 969         struct list_head *cur;
 970         struct btrfs_device *device;
 971         struct backing_dev_info *bdi;
 972
 973         if ((bdi_bits & (1 << BDI_write_congested)) &&
 974             btrfs_congested_async(info, 0))
 975                 return 1;
 976
 977         list_for_each(cur, &info->fs_devices->devices) {
 978                 device = list_entry(cur, struct btrfs_device, dev_list);
 979                 if (!device->bdev)
 980                         continue;
 981                 bdi = blk_get_backing_dev_info(device->bdev);
 982                 if (bdi && bdi_congested(bdi, bdi_bits)) {
 983                         ret = 1;
 984                         break;
 985                 }
 986         }
 987         return ret;
 988 }
 989
 990 /*
 991  * this unplugs every device on the box, and it is only used when page
 992  * is null
 993  */
 994 static void __unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
 995 {
 996         struct list_head *cur;
 997         struct btrfs_device *device;
 998         struct btrfs_fs_info *info;
 999
1000         info = (struct btrfs_fs_info *)bdi->unplug_io_data;
1001         list_for_each(cur, &info->fs_devices->devices) {
1002                 device = list_entry(cur, struct btrfs_device, dev_list);
1003                 bdi = blk_get_backing_dev_info(device->bdev);
1004                 if (bdi->unplug_io_fn) {
1005                         bdi->unplug_io_fn(bdi, page);
1006                 }
1007         }
1008 }
1009
1010 void btrfs_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
1011 {
1012         struct inode *inode;
1013         struct extent_map_tree *em_tree;
1014         struct extent_map *em;
1015         struct address_space *mapping;
1016         u64 offset;
1017
1018         /* the generic O_DIRECT read code does this */
1019         if (!page) {
1020                 __unplug_io_fn(bdi, page);
1021                 return;
1022         }
1023
1024         /*
1025          * page->mapping may change at any time.  Get a consistent copy
1026          * and use that for everything below
1027          */
1028         smp_mb();
1029         mapping = page->mapping;
1030         if (!mapping)
1031                 return;
1032
1033         inode = mapping->host;
1034         offset = page_offset(page);
1035
1036         em_tree = &BTRFS_I(inode)->extent_tree;
1037         spin_lock(&em_tree->lock);
1038         em = lookup_extent_mapping(em_tree, offset, PAGE_CACHE_SIZE);
1039         spin_unlock(&em_tree->lock);
1040         if (!em) {
1041                 __unplug_io_fn(bdi, page);
1042                 return;
1043         }
1044
1045         if (em->block_start >= EXTENT_MAP_LAST_BYTE) {
1046                 free_extent_map(em);
1047                 __unplug_io_fn(bdi, page);
1048                 return;
1049         }
1050         offset = offset - em->start;
1051         btrfs_unplug_page(&BTRFS_I(inode)->root->fs_info->mapping_tree,
1052                           em->block_start + offset, page);
1053         free_extent_map(em);
1054 }
1055
1056 static int setup_bdi(struct btrfs_fs_info *info, struct backing_dev_info *bdi)
1057 {
1058 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,23)
1059         bdi_init(bdi);
1060 #endif
1061         bdi->ra_pages   = default_backing_dev_info.ra_pages;
1062         bdi->state              = 0;
1063         bdi->capabilities       = default_backing_dev_info.capabilities;
1064         bdi->unplug_io_fn       = btrfs_unplug_io_fn;
1065         bdi->unplug_io_data     = info;
1066         bdi->congested_fn       = btrfs_congested_fn;
1067         bdi->congested_data     = info;
1068         return 0;
1069 }
1070
1071 static int bio_ready_for_csum(struct bio *bio)
1072 {
1073         u64 length = 0;
1074         u64 buf_len = 0;
1075         u64 start = 0;
1076         struct page *page;
1077         struct extent_io_tree *io_tree = NULL;
1078         struct btrfs_fs_info *info = NULL;
1079         struct bio_vec *bvec;
1080         int i;
1081         int ret;
1082
1083         bio_for_each_segment(bvec, bio, i) {
1084                 page = bvec->bv_page;
1085                 if (page->private == EXTENT_PAGE_PRIVATE) {
1086                         length += bvec->bv_len;
1087                         continue;
1088                 }
1089                 if (!page->private) {
1090                         length += bvec->bv_len;
1091                         continue;
1092                 }
1093                 length = bvec->bv_len;
1094                 buf_len = page->private >> 2;
1095                 start = page_offset(page) + bvec->bv_offset;
1096                 io_tree = &BTRFS_I(page->mapping->host)->io_tree;
1097                 info = BTRFS_I(page->mapping->host)->root->fs_info;
1098         }
1099         /* are we fully contained in this bio? */
1100         if (buf_len <= length)
1101                 return 1;
1102
1103         ret = extent_range_uptodate(io_tree, start + length,
1104                                     start + buf_len - 1);
1105         if (ret == 1)
1106                 return ret;
1107         return ret;
1108 }
1109
1110 /*
1111  * called by the kthread helper functions to finally call the bio end_io
1112  * functions.  This is where read checksum verification actually happens
1113  */
1114 static void end_workqueue_fn(struct btrfs_work *work)
1115 {
1116         struct bio *bio;
1117         struct end_io_wq *end_io_wq;
1118         struct btrfs_fs_info *fs_info;
1119         int error;
1120
1121         end_io_wq = container_of(work, struct end_io_wq, work);
1122         bio = end_io_wq->bio;
1123         fs_info = end_io_wq->info;
1124
1125         /* metadata bios are special because the whole tree block must
1126          * be checksummed at once.  This makes sure the entire block is in
1127          * ram and up to date before trying to verify things.  For
1128          * blocksize <= pagesize, it is basically a noop
1129          */
1130         if (end_io_wq->metadata && !bio_ready_for_csum(bio)) {
1131                 btrfs_queue_worker(&fs_info->endio_workers,
1132                                    &end_io_wq->work);
1133                 return;
1134         }
1135         error = end_io_wq->error;
1136         bio->bi_private = end_io_wq->private;
1137         bio->bi_end_io = end_io_wq->end_io;
1138         kfree(end_io_wq);
1139 #if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
1140         bio_endio(bio, bio->bi_size, error);
1141 #else
1142         bio_endio(bio, error);
1143 #endif
1144 }
1145
1146 static int cleaner_kthread(void *arg)
1147 {
1148         struct btrfs_root *root = arg;
1149
1150         do {
1151                 smp_mb();
1152                 if (root->fs_info->closing)
1153                         break;
1154
1155                 vfs_check_frozen(root->fs_info->sb, SB_FREEZE_WRITE);
1156                 mutex_lock(&root->fs_info->cleaner_mutex);
1157                 btrfs_clean_old_snapshots(root);
1158                 mutex_unlock(&root->fs_info->cleaner_mutex);
1159
1160                 if (freezing(current)) {
1161                         refrigerator();
1162                 } else {
1163                         smp_mb();
1164                         if (root->fs_info->closing)
1165                                 break;
1166                         set_current_state(TASK_INTERRUPTIBLE);
1167                         schedule();
1168                         __set_current_state(TASK_RUNNING);
1169                 }
1170         } while (!kthread_should_stop());
1171         return 0;
1172 }
1173
1174 static int transaction_kthread(void *arg)
1175 {
1176         struct btrfs_root *root = arg;
1177         struct btrfs_trans_handle *trans;
1178         struct btrfs_transaction *cur;
1179         unsigned long now;
1180         unsigned long delay;
1181         int ret;
1182
1183         do {
1184                 smp_mb();
1185                 if (root->fs_info->closing)
1186                         break;
1187
1188                 delay = HZ * 30;
1189                 vfs_check_frozen(root->fs_info->sb, SB_FREEZE_WRITE);
1190                 mutex_lock(&root->fs_info->transaction_kthread_mutex);
1191
1192                 if (root->fs_info->total_ref_cache_size > 20 * 1024 * 1024) {
1193                         printk("btrfs: total reference cache size %Lu\n",
1194                                 root->fs_info->total_ref_cache_size);
1195                 }
1196
1197                 mutex_lock(&root->fs_info->trans_mutex);
1198                 cur = root->fs_info->running_transaction;
1199                 if (!cur) {
1200                         mutex_unlock(&root->fs_info->trans_mutex);
1201                         goto sleep;
1202                 }
1203
1204                 now = get_seconds();
1205                 if (now < cur->start_time || now - cur->start_time < 30) {
1206                         mutex_unlock(&root->fs_info->trans_mutex);
1207                         delay = HZ * 5;
1208                         goto sleep;
1209                 }
1210                 mutex_unlock(&root->fs_info->trans_mutex);
1211                 trans = btrfs_start_transaction(root, 1);
1212                 ret = btrfs_commit_transaction(trans, root);
1213 sleep:
1214                 wake_up_process(root->fs_info->cleaner_kthread);
1215                 mutex_unlock(&root->fs_info->transaction_kthread_mutex);
1216
1217                 if (freezing(current)) {
1218                         refrigerator();
1219                 } else {
1220                         if (root->fs_info->closing)
1221                                 break;
1222                         set_current_state(TASK_INTERRUPTIBLE);
1223                         schedule_timeout(delay);
1224                         __set_current_state(TASK_RUNNING);
1225                 }
1226         } while (!kthread_should_stop());
1227         return 0;
1228 }
1229
1230 struct btrfs_root *open_ctree(struct super_block *sb,
1231                               struct btrfs_fs_devices *fs_devices,
1232                               char *options)
1233 {
1234         u32 sectorsize;
1235         u32 nodesize;
1236         u32 leafsize;
1237         u32 blocksize;
1238         u32 stripesize;
1239         struct buffer_head *bh;
1240         struct btrfs_root *extent_root = kmalloc(sizeof(struct btrfs_root),
1241                                                  GFP_NOFS);
1242         struct btrfs_root *tree_root = kmalloc(sizeof(struct btrfs_root),
1243                                                GFP_NOFS);
1244         struct btrfs_fs_info *fs_info = kzalloc(sizeof(*fs_info),
1245                                                 GFP_NOFS);
1246         struct btrfs_root *chunk_root = kmalloc(sizeof(struct btrfs_root),
1247                                                 GFP_NOFS);
1248         struct btrfs_root *dev_root = kmalloc(sizeof(struct btrfs_root),
1249                                               GFP_NOFS);
1250         int ret;
1251         int err = -EINVAL;
1252
1253         struct btrfs_super_block *disk_super;
1254
1255         if (!extent_root || !tree_root || !fs_info) {
1256                 err = -ENOMEM;
1257                 goto fail;
1258         }
1259         INIT_RADIX_TREE(&fs_info->fs_roots_radix, GFP_NOFS);
1260         INIT_LIST_HEAD(&fs_info->trans_list);
1261         INIT_LIST_HEAD(&fs_info->dead_roots);
1262         INIT_LIST_HEAD(&fs_info->hashers);
1263         INIT_LIST_HEAD(&fs_info->delalloc_inodes);
1264         spin_lock_init(&fs_info->hash_lock);
1265         spin_lock_init(&fs_info->delalloc_lock);
1266         spin_lock_init(&fs_info->new_trans_lock);
1267         spin_lock_init(&fs_info->ref_cache_lock);
1268
1269         init_completion(&fs_info->kobj_unregister);
1270         fs_info->tree_root = tree_root;
1271         fs_info->extent_root = extent_root;
1272         fs_info->chunk_root = chunk_root;
1273         fs_info->dev_root = dev_root;
1274         fs_info->fs_devices = fs_devices;
1275         INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);
1276         INIT_LIST_HEAD(&fs_info->space_info);
1277         btrfs_mapping_init(&fs_info->mapping_tree);
1278         atomic_set(&fs_info->nr_async_submits, 0);
1279         atomic_set(&fs_info->nr_async_bios, 0);
1280         atomic_set(&fs_info->throttles, 0);
1281         atomic_set(&fs_info->throttle_gen, 0);
1282         fs_info->sb = sb;
1283         fs_info->max_extent = (u64)-1;
1284         fs_info->max_inline = 8192 * 1024;
1285         setup_bdi(fs_info, &fs_info->bdi);
1286         fs_info->btree_inode = new_inode(sb);
1287         fs_info->btree_inode->i_ino = 1;
1288         fs_info->btree_inode->i_nlink = 1;
1289         fs_info->thread_pool_size = min(num_online_cpus() + 2, 8);
1290
1291         INIT_LIST_HEAD(&fs_info->ordered_extents);
1292         spin_lock_init(&fs_info->ordered_extent_lock);
1293
1294         sb->s_blocksize = 4096;
1295         sb->s_blocksize_bits = blksize_bits(4096);
1296
1297         /*
1298          * we set the i_size on the btree inode to the max possible int.
1299          * the real end of the address space is determined by all of
1300          * the devices in the system
1301          */
1302         fs_info->btree_inode->i_size = OFFSET_MAX;
1303         fs_info->btree_inode->i_mapping->a_ops = &btree_aops;
1304         fs_info->btree_inode->i_mapping->backing_dev_info = &fs_info->bdi;
1305
1306         extent_io_tree_init(&BTRFS_I(fs_info->btree_inode)->io_tree,
1307                              fs_info->btree_inode->i_mapping,
1308                              GFP_NOFS);
1309         extent_map_tree_init(&BTRFS_I(fs_info->btree_inode)->extent_tree,
1310                              GFP_NOFS);
1311
1312         BTRFS_I(fs_info->btree_inode)->io_tree.ops = &btree_extent_io_ops;
1313
1314         extent_io_tree_init(&fs_info->free_space_cache,
1315                              fs_info->btree_inode->i_mapping, GFP_NOFS);
1316         extent_io_tree_init(&fs_info->block_group_cache,
1317                              fs_info->btree_inode->i_mapping, GFP_NOFS);
1318         extent_io_tree_init(&fs_info->pinned_extents,
1319                              fs_info->btree_inode->i_mapping, GFP_NOFS);
1320         extent_io_tree_init(&fs_info->pending_del,
1321                              fs_info->btree_inode->i_mapping, GFP_NOFS);
1322         extent_io_tree_init(&fs_info->extent_ins,
1323                              fs_info->btree_inode->i_mapping, GFP_NOFS);
1324         fs_info->do_barriers = 1;
1325
1326         BTRFS_I(fs_info->btree_inode)->root = tree_root;
1327         memset(&BTRFS_I(fs_info->btree_inode)->location, 0,
1328                sizeof(struct btrfs_key));
1329         insert_inode_hash(fs_info->btree_inode);
1330         mapping_set_gfp_mask(fs_info->btree_inode->i_mapping, GFP_NOFS);
1331
1332         mutex_init(&fs_info->trans_mutex);
1333         mutex_init(&fs_info->drop_mutex);
1334         mutex_init(&fs_info->alloc_mutex);
1335         mutex_init(&fs_info->chunk_mutex);
1336         mutex_init(&fs_info->transaction_kthread_mutex);
1337         mutex_init(&fs_info->cleaner_mutex);
1338         mutex_init(&fs_info->volume_mutex);
1339         init_waitqueue_head(&fs_info->transaction_throttle);
1340         init_waitqueue_head(&fs_info->transaction_wait);
1341         init_waitqueue_head(&fs_info->async_submit_wait);
1342
1343 #if 0
1344         ret = add_hasher(fs_info, "crc32c");
1345         if (ret) {
1346                 printk("btrfs: failed hash setup, modprobe cryptomgr?\n");
1347                 err = -ENOMEM;
1348                 goto fail_iput;
1349         }
1350 #endif
1351         __setup_root(4096, 4096, 4096, 4096, tree_root,
1352                      fs_info, BTRFS_ROOT_TREE_OBJECTID);
1353
1354
1355         bh = __bread(fs_devices->latest_bdev,
1356                      BTRFS_SUPER_INFO_OFFSET / 4096, 4096);
1357         if (!bh)
1358                 goto fail_iput;
1359
1360         memcpy(&fs_info->super_copy, bh->b_data, sizeof(fs_info->super_copy));
1361         brelse(bh);
1362
1363         memcpy(fs_info->fsid, fs_info->super_copy.fsid, BTRFS_FSID_SIZE);
1364
1365         disk_super = &fs_info->super_copy;
1366         if (!btrfs_super_root(disk_super))
1367                 goto fail_sb_buffer;
1368
1369         err = btrfs_parse_options(tree_root, options);
1370         if (err)
1371                 goto fail_sb_buffer;
1372
1373         /*
1374          * we need to start all the end_io workers up front because the
1375          * queue work function gets called at interrupt time, and so it
1376          * cannot dynamically grow.
1377          */
1378         btrfs_init_workers(&fs_info->workers, "worker",
1379                            fs_info->thread_pool_size);
1380         btrfs_init_workers(&fs_info->submit_workers, "submit",
1381                            min_t(u64, fs_devices->num_devices,
1382                            fs_info->thread_pool_size));
1383
1384         /* a higher idle thresh on the submit workers makes it much more
1385          * likely that bios will be send down in a sane order to the
1386          * devices
1387          */
1388         fs_info->submit_workers.idle_thresh = 64;
1389
1390         /* fs_info->workers is responsible for checksumming file data
1391          * blocks and metadata.  Using a larger idle thresh allows each
1392          * worker thread to operate on things in roughly the order they
1393          * were sent by the writeback daemons, improving overall locality
1394          * of the IO going down the pipe.
1395          */
1396         fs_info->workers.idle_thresh = 128;
1397
1398         btrfs_init_workers(&fs_info->fixup_workers, "fixup", 1);
1399         btrfs_init_workers(&fs_info->endio_workers, "endio",
1400                            fs_info->thread_pool_size);
1401         btrfs_init_workers(&fs_info->endio_write_workers, "endio-write",
1402                            fs_info->thread_pool_size);
1403
1404         /*
1405          * endios are largely parallel and should have a very
1406          * low idle thresh
1407          */
1408         fs_info->endio_workers.idle_thresh = 4;
1409         fs_info->endio_write_workers.idle_thresh = 4;
1410
1411         btrfs_start_workers(&fs_info->workers, 1);
1412         btrfs_start_workers(&fs_info->submit_workers, 1);
1413         btrfs_start_workers(&fs_info->fixup_workers, 1);
1414         btrfs_start_workers(&fs_info->endio_workers, fs_info->thread_pool_size);
1415         btrfs_start_workers(&fs_info->endio_write_workers,
1416                             fs_info->thread_pool_size);
1417
1418         err = -EINVAL;
1419         if (btrfs_super_num_devices(disk_super) > fs_devices->open_devices) {
1420                 printk("Btrfs: wanted %llu devices, but found %llu\n",
1421                        (unsigned long long)btrfs_super_num_devices(disk_super),
1422                        (unsigned long long)fs_devices->open_devices);
1423                 if (btrfs_test_opt(tree_root, DEGRADED))
1424                         printk("continuing in degraded mode\n");
1425                 else {
1426                         goto fail_sb_buffer;
1427                 }
1428         }
1429
1430         fs_info->bdi.ra_pages *= btrfs_super_num_devices(disk_super);
1431
1432         nodesize = btrfs_super_nodesize(disk_super);
1433         leafsize = btrfs_super_leafsize(disk_super);
1434         sectorsize = btrfs_super_sectorsize(disk_super);
1435         stripesize = btrfs_super_stripesize(disk_super);
1436         tree_root->nodesize = nodesize;
1437         tree_root->leafsize = leafsize;
1438         tree_root->sectorsize = sectorsize;
1439         tree_root->stripesize = stripesize;
1440
1441         sb->s_blocksize = sectorsize;
1442         sb->s_blocksize_bits = blksize_bits(sectorsize);
1443
1444         if (strncmp((char *)(&disk_super->magic), BTRFS_MAGIC,
1445                     sizeof(disk_super->magic))) {
1446                 printk("btrfs: valid FS not found on %s\n", sb->s_id);
1447                 goto fail_sb_buffer;
1448         }
1449
1450         mutex_lock(&fs_info->chunk_mutex);
1451         ret = btrfs_read_sys_array(tree_root);
1452         mutex_unlock(&fs_info->chunk_mutex);
1453         if (ret) {
1454                 printk("btrfs: failed to read the system array on %s\n",
1455                        sb->s_id);
1456                 goto fail_sys_array;
1457         }
1458
1459         blocksize = btrfs_level_size(tree_root,
1460                                      btrfs_super_chunk_root_level(disk_super));
1461
1462         __setup_root(nodesize, leafsize, sectorsize, stripesize,
1463                      chunk_root, fs_info, BTRFS_CHUNK_TREE_OBJECTID);
1464
1465         chunk_root->node = read_tree_block(chunk_root,
1466                                            btrfs_super_chunk_root(disk_super),
1467                                            blocksize, 0);
1468         BUG_ON(!chunk_root->node);
1469
1470         read_extent_buffer(chunk_root->node, fs_info->chunk_tree_uuid,
1471                  (unsigned long)btrfs_header_chunk_tree_uuid(chunk_root->node),
1472                  BTRFS_UUID_SIZE);
1473
1474         mutex_lock(&fs_info->chunk_mutex);
1475         ret = btrfs_read_chunk_tree(chunk_root);
1476         mutex_unlock(&fs_info->chunk_mutex);
1477         BUG_ON(ret);
1478
1479         btrfs_close_extra_devices(fs_devices);
1480
1481         blocksize = btrfs_level_size(tree_root,
1482                                      btrfs_super_root_level(disk_super));
1483
1484
1485         tree_root->node = read_tree_block(tree_root,
1486                                           btrfs_super_root(disk_super),
1487                                           blocksize, 0);
1488         if (!tree_root->node)
1489                 goto fail_sb_buffer;
1490
1491
1492         ret = find_and_setup_root(tree_root, fs_info,
1493                                   BTRFS_EXTENT_TREE_OBJECTID, extent_root);
1494         if (ret)
1495                 goto fail_tree_root;
1496         extent_root->track_dirty = 1;
1497
1498         ret = find_and_setup_root(tree_root, fs_info,
1499                                   BTRFS_DEV_TREE_OBJECTID, dev_root);
1500         dev_root->track_dirty = 1;
1501
1502         if (ret)
1503                 goto fail_extent_root;
1504
1505         btrfs_read_block_groups(extent_root);
1506
1507         fs_info->generation = btrfs_super_generation(disk_super) + 1;
1508         fs_info->data_alloc_profile = (u64)-1;
1509         fs_info->metadata_alloc_profile = (u64)-1;
1510         fs_info->system_alloc_profile = fs_info->metadata_alloc_profile;
1511         fs_info->cleaner_kthread = kthread_run(cleaner_kthread, tree_root,
1512                                                "btrfs-cleaner");
1513         if (!fs_info->cleaner_kthread)
1514                 goto fail_extent_root;
1515
1516         fs_info->transaction_kthread = kthread_run(transaction_kthread,
1517                                                    tree_root,
1518                                                    "btrfs-transaction");
1519         if (!fs_info->transaction_kthread)
1520                 goto fail_cleaner;
1521
1522
1523         return tree_root;
1524
1525 fail_cleaner:
1526         kthread_stop(fs_info->cleaner_kthread);
1527 fail_extent_root:
1528         free_extent_buffer(extent_root->node);
1529 fail_tree_root:
1530         free_extent_buffer(tree_root->node);
1531 fail_sys_array:
1532 fail_sb_buffer:
1533         btrfs_stop_workers(&fs_info->fixup_workers);
1534         btrfs_stop_workers(&fs_info->workers);
1535         btrfs_stop_workers(&fs_info->endio_workers);
1536         btrfs_stop_workers(&fs_info->endio_write_workers);
1537         btrfs_stop_workers(&fs_info->submit_workers);
1538 fail_iput:
1539         iput(fs_info->btree_inode);
1540 fail:
1541         btrfs_close_devices(fs_info->fs_devices);
1542         btrfs_mapping_tree_free(&fs_info->mapping_tree);
1543
1544         kfree(extent_root);
1545         kfree(tree_root);
1546 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,23)
1547         bdi_destroy(&fs_info->bdi);
1548 #endif
1549         kfree(fs_info);
1550         return ERR_PTR(err);
1551 }
1552
1553 static void btrfs_end_buffer_write_sync(struct buffer_head *bh, int uptodate)
1554 {
1555         char b[BDEVNAME_SIZE];
1556
1557         if (uptodate) {
1558                 set_buffer_uptodate(bh);
1559         } else {
1560                 if (!buffer_eopnotsupp(bh) && printk_ratelimit()) {
1561                         printk(KERN_WARNING "lost page write due to "
1562                                         "I/O error on %s\n",
1563                                        bdevname(bh->b_bdev, b));
1564                 }
1565                 /* note, we dont' set_buffer_write_io_error because we have
1566                  * our own ways of dealing with the IO errors
1567                  */
1568                 clear_buffer_uptodate(bh);
1569         }
1570         unlock_buffer(bh);
1571         put_bh(bh);
1572 }
1573
1574 int write_all_supers(struct btrfs_root *root)
1575 {
1576         struct list_head *cur;
1577         struct list_head *head = &root->fs_info->fs_devices->devices;
1578         struct btrfs_device *dev;
1579         struct btrfs_super_block *sb;
1580         struct btrfs_dev_item *dev_item;
1581         struct buffer_head *bh;
1582         int ret;
1583         int do_barriers;
1584         int max_errors;
1585         int total_errors = 0;
1586         u32 crc;
1587         u64 flags;
1588
1589         max_errors = btrfs_super_num_devices(&root->fs_info->super_copy) - 1;
1590         do_barriers = !btrfs_test_opt(root, NOBARRIER);
1591
1592         sb = &root->fs_info->super_for_commit;
1593         dev_item = &sb->dev_item;
1594         list_for_each(cur, head) {
1595                 dev = list_entry(cur, struct btrfs_device, dev_list);
1596                 if (!dev->bdev) {
1597                         total_errors++;
1598                         continue;
1599                 }
1600                 if (!dev->in_fs_metadata)
1601                         continue;
1602
1603                 btrfs_set_stack_device_type(dev_item, dev->type);
1604                 btrfs_set_stack_device_id(dev_item, dev->devid);
1605                 btrfs_set_stack_device_total_bytes(dev_item, dev->total_bytes);
1606                 btrfs_set_stack_device_bytes_used(dev_item, dev->bytes_used);
1607                 btrfs_set_stack_device_io_align(dev_item, dev->io_align);
1608                 btrfs_set_stack_device_io_width(dev_item, dev->io_width);
1609                 btrfs_set_stack_device_sector_size(dev_item, dev->sector_size);
1610                 memcpy(dev_item->uuid, dev->uuid, BTRFS_UUID_SIZE);
1611                 flags = btrfs_super_flags(sb);
1612                 btrfs_set_super_flags(sb, flags | BTRFS_HEADER_FLAG_WRITTEN);
1613
1614
1615                 crc = ~(u32)0;
1616                 crc = btrfs_csum_data(root, (char *)sb + BTRFS_CSUM_SIZE, crc,
1617                                       BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE);
1618                 btrfs_csum_final(crc, sb->csum);
1619
1620                 bh = __getblk(dev->bdev, BTRFS_SUPER_INFO_OFFSET / 4096,
1621                               BTRFS_SUPER_INFO_SIZE);
1622
1623                 memcpy(bh->b_data, sb, BTRFS_SUPER_INFO_SIZE);
1624                 dev->pending_io = bh;
1625
1626                 get_bh(bh);
1627                 set_buffer_uptodate(bh);
1628                 lock_buffer(bh);
1629                 bh->b_end_io = btrfs_end_buffer_write_sync;
1630
1631                 if (do_barriers && dev->barriers) {
1632                         ret = submit_bh(WRITE_BARRIER, bh);
1633                         if (ret == -EOPNOTSUPP) {
1634                                 printk("btrfs: disabling barriers on dev %s\n",
1635                                        dev->name);
1636                                 set_buffer_uptodate(bh);
1637                                 dev->barriers = 0;
1638                                 get_bh(bh);
1639                                 lock_buffer(bh);
1640                                 ret = submit_bh(WRITE, bh);
1641                         }
1642                 } else {
1643                         ret = submit_bh(WRITE, bh);
1644                 }
1645                 if (ret)
1646                         total_errors++;
1647         }
1648         if (total_errors > max_errors) {
1649                 printk("btrfs: %d errors while writing supers\n", total_errors);
1650                 BUG();
1651         }
1652         total_errors = 0;
1653
1654         list_for_each(cur, head) {
1655                 dev = list_entry(cur, struct btrfs_device, dev_list);
1656                 if (!dev->bdev)
1657                         continue;
1658                 if (!dev->in_fs_metadata)
1659                         continue;
1660
1661                 BUG_ON(!dev->pending_io);
1662                 bh = dev->pending_io;
1663                 wait_on_buffer(bh);
1664                 if (!buffer_uptodate(dev->pending_io)) {
1665                         if (do_barriers && dev->barriers) {
1666                                 printk("btrfs: disabling barriers on dev %s\n",
1667                                        dev->name);
1668                                 set_buffer_uptodate(bh);
1669                                 get_bh(bh);
1670                                 lock_buffer(bh);
1671                                 dev->barriers = 0;
1672                                 ret = submit_bh(WRITE, bh);
1673                                 BUG_ON(ret);
1674                                 wait_on_buffer(bh);
1675                                 if (!buffer_uptodate(bh))
1676                                         total_errors++;
1677                         } else {
1678                                 total_errors++;
1679                         }
1680
1681                 }
1682                 dev->pending_io = NULL;
1683                 brelse(bh);
1684         }
1685         if (total_errors > max_errors) {
1686                 printk("btrfs: %d errors while writing supers\n", total_errors);
1687                 BUG();
1688         }
1689         return 0;
1690 }
1691
1692 int write_ctree_super(struct btrfs_trans_handle *trans, struct btrfs_root
1693                       *root)
1694 {
1695         int ret;
1696
1697         ret = write_all_supers(root);
1698         return ret;
1699 }
1700
1701 int btrfs_free_fs_root(struct btrfs_fs_info *fs_info, struct btrfs_root *root)
1702 {
1703         radix_tree_delete(&fs_info->fs_roots_radix,
1704                           (unsigned long)root->root_key.objectid);
1705         if (root->in_sysfs)
1706                 btrfs_sysfs_del_root(root);
1707         if (root->inode)
1708                 iput(root->inode);
1709         if (root->node)
1710                 free_extent_buffer(root->node);
1711         if (root->commit_root)
1712                 free_extent_buffer(root->commit_root);
1713         if (root->name)
1714                 kfree(root->name);
1715         kfree(root);
1716         return 0;
1717 }
1718
1719 static int del_fs_roots(struct btrfs_fs_info *fs_info)
1720 {
1721         int ret;
1722         struct btrfs_root *gang[8];
1723         int i;
1724
1725         while(1) {
1726                 ret = radix_tree_gang_lookup(&fs_info->fs_roots_radix,
1727                                              (void **)gang, 0,
1728                                              ARRAY_SIZE(gang));
1729                 if (!ret)
1730                         break;
1731                 for (i = 0; i < ret; i++)
1732                         btrfs_free_fs_root(fs_info, gang[i]);
1733         }
1734         return 0;
1735 }
1736
1737 int close_ctree(struct btrfs_root *root)
1738 {
1739         int ret;
1740         struct btrfs_trans_handle *trans;
1741         struct btrfs_fs_info *fs_info = root->fs_info;
1742
1743         fs_info->closing = 1;
1744         smp_mb();
1745
1746         kthread_stop(root->fs_info->transaction_kthread);
1747         kthread_stop(root->fs_info->cleaner_kthread);
1748
1749         btrfs_clean_old_snapshots(root);
1750         trans = btrfs_start_transaction(root, 1);
1751         ret = btrfs_commit_transaction(trans, root);
1752         /* run commit again to  drop the original snapshot */
1753         trans = btrfs_start_transaction(root, 1);
1754         btrfs_commit_transaction(trans, root);
1755         ret = btrfs_write_and_wait_transaction(NULL, root);
1756         BUG_ON(ret);
1757
1758         write_ctree_super(NULL, root);
1759
1760         if (fs_info->delalloc_bytes) {
1761                 printk("btrfs: at unmount delalloc count %Lu\n",
1762                        fs_info->delalloc_bytes);
1763         }
1764         if (fs_info->total_ref_cache_size) {
1765                 printk("btrfs: at umount reference cache size %Lu\n",
1766                         fs_info->total_ref_cache_size);
1767         }
1768
1769         if (fs_info->extent_root->node)
1770                 free_extent_buffer(fs_info->extent_root->node);
1771
1772         if (fs_info->tree_root->node)
1773                 free_extent_buffer(fs_info->tree_root->node);
1774
1775         if (root->fs_info->chunk_root->node);
1776                 free_extent_buffer(root->fs_info->chunk_root->node);
1777
1778         if (root->fs_info->dev_root->node);
1779                 free_extent_buffer(root->fs_info->dev_root->node);
1780
1781         btrfs_free_block_groups(root->fs_info);
1782         fs_info->closing = 2;
1783         del_fs_roots(fs_info);
1784
1785         filemap_write_and_wait(fs_info->btree_inode->i_mapping);
1786
1787         truncate_inode_pages(fs_info->btree_inode->i_mapping, 0);
1788
1789         btrfs_stop_workers(&fs_info->fixup_workers);
1790         btrfs_stop_workers(&fs_info->workers);
1791         btrfs_stop_workers(&fs_info->endio_workers);
1792         btrfs_stop_workers(&fs_info->endio_write_workers);
1793         btrfs_stop_workers(&fs_info->submit_workers);
1794
1795         iput(fs_info->btree_inode);
1796 #if 0
1797         while(!list_empty(&fs_info->hashers)) {
1798                 struct btrfs_hasher *hasher;
1799                 hasher = list_entry(fs_info->hashers.next, struct btrfs_hasher,
1800                                     hashers);
1801                 list_del(&hasher->hashers);
1802                 crypto_free_hash(&fs_info->hash_tfm);
1803                 kfree(hasher);
1804         }
1805 #endif
1806         btrfs_close_devices(fs_info->fs_devices);
1807         btrfs_mapping_tree_free(&fs_info->mapping_tree);
1808
1809 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,23)
1810         bdi_destroy(&fs_info->bdi);
1811 #endif
1812
1813         kfree(fs_info->extent_root);
1814         kfree(fs_info->tree_root);
1815         kfree(fs_info->chunk_root);
1816         kfree(fs_info->dev_root);
1817         return 0;
1818 }
1819
1820 int btrfs_buffer_uptodate(struct extent_buffer *buf, u64 parent_transid)
1821 {
1822         int ret;
1823         struct inode *btree_inode = buf->first_page->mapping->host;
1824
1825         ret = extent_buffer_uptodate(&BTRFS_I(btree_inode)->io_tree, buf);
1826         if (!ret)
1827                 return ret;
1828
1829         ret = verify_parent_transid(&BTRFS_I(btree_inode)->io_tree, buf,
1830                                     parent_transid);
1831         return !ret;
1832 }
1833
1834 int btrfs_set_buffer_uptodate(struct extent_buffer *buf)
1835 {
1836         struct inode *btree_inode = buf->first_page->mapping->host;
1837         return set_extent_buffer_uptodate(&BTRFS_I(btree_inode)->io_tree,
1838                                           buf);
1839 }
1840
1841 void btrfs_mark_buffer_dirty(struct extent_buffer *buf)
1842 {
1843         struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
1844         u64 transid = btrfs_header_generation(buf);
1845         struct inode *btree_inode = root->fs_info->btree_inode;
1846
1847         WARN_ON(!btrfs_tree_locked(buf));
1848         if (transid != root->fs_info->generation) {
1849                 printk(KERN_CRIT "transid mismatch buffer %llu, found %Lu running %Lu\n",
1850                         (unsigned long long)buf->start,
1851                         transid, root->fs_info->generation);
1852                 WARN_ON(1);
1853         }
1854         set_extent_buffer_dirty(&BTRFS_I(btree_inode)->io_tree, buf);
1855 }
1856
1857 void btrfs_btree_balance_dirty(struct btrfs_root *root, unsigned long nr)
1858 {
1859         /*
1860          * looks as though older kernels can get into trouble with
1861          * this code, they end up stuck in balance_dirty_pages forever
1862          */
1863         struct extent_io_tree *tree;
1864         u64 num_dirty;
1865         u64 start = 0;
1866         unsigned long thresh = 12 * 1024 * 1024;
1867         tree = &BTRFS_I(root->fs_info->btree_inode)->io_tree;
1868
1869         if (current_is_pdflush())
1870                 return;
1871
1872         num_dirty = count_range_bits(tree, &start, (u64)-1,
1873                                      thresh, EXTENT_DIRTY);
1874         if (num_dirty > thresh) {
1875                 balance_dirty_pages_ratelimited_nr(
1876                                    root->fs_info->btree_inode->i_mapping, 1);
1877         }
1878         return;
1879 }
1880
1881 int btrfs_read_buffer(struct extent_buffer *buf, u64 parent_transid)
1882 {
1883         struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
1884         int ret;
1885         ret = btree_read_extent_buffer_pages(root, buf, 0, parent_transid);
1886         if (ret == 0) {
1887                 buf->flags |= EXTENT_UPTODATE;
1888         }
1889         return ret;
1890 }
1891
1892 static struct extent_io_ops btree_extent_io_ops = {
1893         .writepage_io_hook = btree_writepage_io_hook,
1894         .readpage_end_io_hook = btree_readpage_end_io_hook,
1895         .submit_bio_hook = btree_submit_bio_hook,
1896         /* note we're sharing with inode.c for the merge bio hook */
1897         .merge_bio_hook = btrfs_merge_bio_hook,
1898 };