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   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 unsigned long btrfs_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) >
 443                 btrfs_async_submit_limit(info);
 444 }
 445
 446 static void run_one_async_submit(struct btrfs_work *work)
 447 {
 448         struct btrfs_fs_info *fs_info;
 449         struct async_submit_bio *async;
 450         int limit;
 451
 452         async = container_of(work, struct  async_submit_bio, work);
 453         fs_info = BTRFS_I(async->inode)->root->fs_info;
 454
 455         limit = btrfs_async_submit_limit(fs_info);
 456         limit = limit * 2 / 3;
 457
 458         atomic_dec(&fs_info->nr_async_submits);
 459
 460         if (atomic_read(&fs_info->nr_async_submits) < limit &&
 461             waitqueue_active(&fs_info->async_submit_wait))
 462                 wake_up(&fs_info->async_submit_wait);
 463
 464         async->submit_bio_hook(async->inode, async->rw, async->bio,
 465                                async->mirror_num);
 466         kfree(async);
 467 }
 468
 469 int btrfs_wq_submit_bio(struct btrfs_fs_info *fs_info, struct inode *inode,
 470                         int rw, struct bio *bio, int mirror_num,
 471                         extent_submit_bio_hook_t *submit_bio_hook)
 472 {
 473         struct async_submit_bio *async;
 474         int limit = btrfs_async_submit_limit(fs_info);
 475
 476         async = kmalloc(sizeof(*async), GFP_NOFS);
 477         if (!async)
 478                 return -ENOMEM;
 479
 480         async->inode = inode;
 481         async->rw = rw;
 482         async->bio = bio;
 483         async->mirror_num = mirror_num;
 484         async->submit_bio_hook = submit_bio_hook;
 485         async->work.func = run_one_async_submit;
 486         async->work.flags = 0;
 487         atomic_inc(&fs_info->nr_async_submits);
 488         btrfs_queue_worker(&fs_info->workers, &async->work);
 489
 490         if (atomic_read(&fs_info->nr_async_submits) > limit) {
 491                 wait_event_timeout(fs_info->async_submit_wait,
 492                            (atomic_read(&fs_info->nr_async_submits) < limit),
 493                            HZ/10);
 494
 495                 wait_event_timeout(fs_info->async_submit_wait,
 496                            (atomic_read(&fs_info->nr_async_bios) < limit),
 497                            HZ/10);
 498         }
 499         return 0;
 500 }
 501
 502 static int __btree_submit_bio_hook(struct inode *inode, int rw, struct bio *bio,
 503                                  int mirror_num)
 504 {
 505         struct btrfs_root *root = BTRFS_I(inode)->root;
 506         u64 offset;
 507         int ret;
 508
 509         offset = bio->bi_sector << 9;
 510
 511         /*
 512          * when we're called for a write, we're already in the async
 513          * submission context.  Just jump into btrfs_map_bio
 514          */
 515         if (rw & (1 << BIO_RW)) {
 516                 return btrfs_map_bio(BTRFS_I(inode)->root, rw, bio,
 517                                      mirror_num, 1);
 518         }
 519
 520         /*
 521          * called for a read, do the setup so that checksum validation
 522          * can happen in the async kernel threads
 523          */
 524         ret = btrfs_bio_wq_end_io(root->fs_info, bio, 1);
 525         BUG_ON(ret);
 526
 527         return btrfs_map_bio(BTRFS_I(inode)->root, rw, bio, mirror_num, 1);
 528 }
 529
 530 static int btree_submit_bio_hook(struct inode *inode, int rw, struct bio *bio,
 531                                  int mirror_num)
 532 {
 533         /*
 534          * kthread helpers are used to submit writes so that checksumming
 535          * can happen in parallel across all CPUs
 536          */
 537         if (!(rw & (1 << BIO_RW))) {
 538                 return __btree_submit_bio_hook(inode, rw, bio, mirror_num);
 539         }
 540         return btrfs_wq_submit_bio(BTRFS_I(inode)->root->fs_info,
 541                                    inode, rw, bio, mirror_num,
 542                                    __btree_submit_bio_hook);
 543 }
 544
 545 static int btree_writepage(struct page *page, struct writeback_control *wbc)
 546 {
 547         struct extent_io_tree *tree;
 548         tree = &BTRFS_I(page->mapping->host)->io_tree;
 549
 550         if (current->flags & PF_MEMALLOC) {
 551                 redirty_page_for_writepage(wbc, page);
 552                 unlock_page(page);
 553                 return 0;
 554         }
 555         return extent_write_full_page(tree, page, btree_get_extent, wbc);
 556 }
 557
 558 static int btree_writepages(struct address_space *mapping,
 559                             struct writeback_control *wbc)
 560 {
 561         struct extent_io_tree *tree;
 562         tree = &BTRFS_I(mapping->host)->io_tree;
 563         if (wbc->sync_mode == WB_SYNC_NONE) {
 564                 u64 num_dirty;
 565                 u64 start = 0;
 566                 unsigned long thresh = 8 * 1024 * 1024;
 567
 568                 if (wbc->for_kupdate)
 569                         return 0;
 570
 571                 num_dirty = count_range_bits(tree, &start, (u64)-1,
 572                                              thresh, EXTENT_DIRTY);
 573                 if (num_dirty < thresh) {
 574                         return 0;
 575                 }
 576         }
 577         return extent_writepages(tree, mapping, btree_get_extent, wbc);
 578 }
 579
 580 int btree_readpage(struct file *file, struct page *page)
 581 {
 582         struct extent_io_tree *tree;
 583         tree = &BTRFS_I(page->mapping->host)->io_tree;
 584         return extent_read_full_page(tree, page, btree_get_extent);
 585 }
 586
 587 static int btree_releasepage(struct page *page, gfp_t gfp_flags)
 588 {
 589         struct extent_io_tree *tree;
 590         struct extent_map_tree *map;
 591         int ret;
 592
 593         tree = &BTRFS_I(page->mapping->host)->io_tree;
 594         map = &BTRFS_I(page->mapping->host)->extent_tree;
 595
 596         ret = try_release_extent_state(map, tree, page, gfp_flags);
 597         if (!ret) {
 598                 return 0;
 599         }
 600
 601         ret = try_release_extent_buffer(tree, page);
 602         if (ret == 1) {
 603                 ClearPagePrivate(page);
 604                 set_page_private(page, 0);
 605                 page_cache_release(page);
 606         }
 607
 608         return ret;
 609 }
 610
 611 static void btree_invalidatepage(struct page *page, unsigned long offset)
 612 {
 613         struct extent_io_tree *tree;
 614         tree = &BTRFS_I(page->mapping->host)->io_tree;
 615         extent_invalidatepage(tree, page, offset);
 616         btree_releasepage(page, GFP_NOFS);
 617         if (PagePrivate(page)) {
 618                 printk("warning page private not zero on page %Lu\n",
 619                        page_offset(page));
 620                 ClearPagePrivate(page);
 621                 set_page_private(page, 0);
 622                 page_cache_release(page);
 623         }
 624 }
 625
 626 #if 0
 627 static int btree_writepage(struct page *page, struct writeback_control *wbc)
 628 {
 629         struct buffer_head *bh;
 630         struct btrfs_root *root = BTRFS_I(page->mapping->host)->root;
 631         struct buffer_head *head;
 632         if (!page_has_buffers(page)) {
 633                 create_empty_buffers(page, root->fs_info->sb->s_blocksize,
 634                                         (1 << BH_Dirty)|(1 << BH_Uptodate));
 635         }
 636         head = page_buffers(page);
 637         bh = head;
 638         do {
 639                 if (buffer_dirty(bh))
 640                         csum_tree_block(root, bh, 0);
 641                 bh = bh->b_this_page;
 642         } while (bh != head);
 643         return block_write_full_page(page, btree_get_block, wbc);
 644 }
 645 #endif
 646
 647 static struct address_space_operations btree_aops = {
 648         .readpage       = btree_readpage,
 649         .writepage      = btree_writepage,
 650         .writepages     = btree_writepages,
 651         .releasepage    = btree_releasepage,
 652         .invalidatepage = btree_invalidatepage,
 653         .sync_page      = block_sync_page,
 654 };
 655
 656 int readahead_tree_block(struct btrfs_root *root, u64 bytenr, u32 blocksize,
 657                          u64 parent_transid)
 658 {
 659         struct extent_buffer *buf = NULL;
 660         struct inode *btree_inode = root->fs_info->btree_inode;
 661         int ret = 0;
 662
 663         buf = btrfs_find_create_tree_block(root, bytenr, blocksize);
 664         if (!buf)
 665                 return 0;
 666         read_extent_buffer_pages(&BTRFS_I(btree_inode)->io_tree,
 667                                  buf, 0, 0, btree_get_extent, 0);
 668         free_extent_buffer(buf);
 669         return ret;
 670 }
 671
 672 struct extent_buffer *btrfs_find_tree_block(struct btrfs_root *root,
 673                                             u64 bytenr, u32 blocksize)
 674 {
 675         struct inode *btree_inode = root->fs_info->btree_inode;
 676         struct extent_buffer *eb;
 677         eb = find_extent_buffer(&BTRFS_I(btree_inode)->io_tree,
 678                                 bytenr, blocksize, GFP_NOFS);
 679         return eb;
 680 }
 681
 682 struct extent_buffer *btrfs_find_create_tree_block(struct btrfs_root *root,
 683                                                  u64 bytenr, u32 blocksize)
 684 {
 685         struct inode *btree_inode = root->fs_info->btree_inode;
 686         struct extent_buffer *eb;
 687
 688         eb = alloc_extent_buffer(&BTRFS_I(btree_inode)->io_tree,
 689                                  bytenr, blocksize, NULL, GFP_NOFS);
 690         return eb;
 691 }
 692
 693
 694 struct extent_buffer *read_tree_block(struct btrfs_root *root, u64 bytenr,
 695                                       u32 blocksize, u64 parent_transid)
 696 {
 697         struct extent_buffer *buf = NULL;
 698         struct inode *btree_inode = root->fs_info->btree_inode;
 699         struct extent_io_tree *io_tree;
 700         int ret;
 701
 702         io_tree = &BTRFS_I(btree_inode)->io_tree;
 703
 704         buf = btrfs_find_create_tree_block(root, bytenr, blocksize);
 705         if (!buf)
 706                 return NULL;
 707
 708         ret = btree_read_extent_buffer_pages(root, buf, 0, parent_transid);
 709
 710         if (ret == 0) {
 711                 buf->flags |= EXTENT_UPTODATE;
 712         }
 713         return buf;
 714
 715 }
 716
 717 int clean_tree_block(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 718                      struct extent_buffer *buf)
 719 {
 720         struct inode *btree_inode = root->fs_info->btree_inode;
 721         if (btrfs_header_generation(buf) ==
 722             root->fs_info->running_transaction->transid) {
 723                 WARN_ON(!btrfs_tree_locked(buf));
 724                 clear_extent_buffer_dirty(&BTRFS_I(btree_inode)->io_tree,
 725                                           buf);
 726         }
 727         return 0;
 728 }
 729
 730 int wait_on_tree_block_writeback(struct btrfs_root *root,
 731                                  struct extent_buffer *buf)
 732 {
 733         struct inode *btree_inode = root->fs_info->btree_inode;
 734         wait_on_extent_buffer_writeback(&BTRFS_I(btree_inode)->io_tree,
 735                                         buf);
 736         return 0;
 737 }
 738
 739 static int __setup_root(u32 nodesize, u32 leafsize, u32 sectorsize,
 740                         u32 stripesize, struct btrfs_root *root,
 741                         struct btrfs_fs_info *fs_info,
 742                         u64 objectid)
 743 {
 744         root->node = NULL;
 745         root->inode = NULL;
 746         root->commit_root = NULL;
 747         root->ref_tree = NULL;
 748         root->sectorsize = sectorsize;
 749         root->nodesize = nodesize;
 750         root->leafsize = leafsize;
 751         root->stripesize = stripesize;
 752         root->ref_cows = 0;
 753         root->track_dirty = 0;
 754
 755         root->fs_info = fs_info;
 756         root->objectid = objectid;
 757         root->last_trans = 0;
 758         root->highest_inode = 0;
 759         root->last_inode_alloc = 0;
 760         root->name = NULL;
 761         root->in_sysfs = 0;
 762
 763         INIT_LIST_HEAD(&root->dirty_list);
 764         INIT_LIST_HEAD(&root->orphan_list);
 765         INIT_LIST_HEAD(&root->dead_list);
 766         spin_lock_init(&root->node_lock);
 767         spin_lock_init(&root->list_lock);
 768         mutex_init(&root->objectid_mutex);
 769
 770         btrfs_leaf_ref_tree_init(&root->ref_tree_struct);
 771         root->ref_tree = &root->ref_tree_struct;
 772
 773         memset(&root->root_key, 0, sizeof(root->root_key));
 774         memset(&root->root_item, 0, sizeof(root->root_item));
 775         memset(&root->defrag_progress, 0, sizeof(root->defrag_progress));
 776         memset(&root->root_kobj, 0, sizeof(root->root_kobj));
 777         root->defrag_trans_start = fs_info->generation;
 778         init_completion(&root->kobj_unregister);
 779         root->defrag_running = 0;
 780         root->defrag_level = 0;
 781         root->root_key.objectid = objectid;
 782         return 0;
 783 }
 784
 785 static int find_and_setup_root(struct btrfs_root *tree_root,
 786                                struct btrfs_fs_info *fs_info,
 787                                u64 objectid,
 788                                struct btrfs_root *root)
 789 {
 790         int ret;
 791         u32 blocksize;
 792
 793         __setup_root(tree_root->nodesize, tree_root->leafsize,
 794                      tree_root->sectorsize, tree_root->stripesize,
 795                      root, fs_info, objectid);
 796         ret = btrfs_find_last_root(tree_root, objectid,
 797                                    &root->root_item, &root->root_key);
 798         BUG_ON(ret);
 799
 800         blocksize = btrfs_level_size(root, btrfs_root_level(&root->root_item));
 801         root->node = read_tree_block(root, btrfs_root_bytenr(&root->root_item),
 802                                      blocksize, 0);
 803         BUG_ON(!root->node);
 804         return 0;
 805 }
 806
 807 struct btrfs_root *btrfs_read_fs_root_no_radix(struct btrfs_fs_info *fs_info,
 808                                                struct btrfs_key *location)
 809 {
 810         struct btrfs_root *root;
 811         struct btrfs_root *tree_root = fs_info->tree_root;
 812         struct btrfs_path *path;
 813         struct extent_buffer *l;
 814         u64 highest_inode;
 815         u32 blocksize;
 816         int ret = 0;
 817
 818         root = kzalloc(sizeof(*root), GFP_NOFS);
 819         if (!root)
 820                 return ERR_PTR(-ENOMEM);
 821         if (location->offset == (u64)-1) {
 822                 ret = find_and_setup_root(tree_root, fs_info,
 823                                           location->objectid, root);
 824                 if (ret) {
 825                         kfree(root);
 826                         return ERR_PTR(ret);
 827                 }
 828                 goto insert;
 829         }
 830
 831         __setup_root(tree_root->nodesize, tree_root->leafsize,
 832                      tree_root->sectorsize, tree_root->stripesize,
 833                      root, fs_info, location->objectid);
 834
 835         path = btrfs_alloc_path();
 836         BUG_ON(!path);
 837         ret = btrfs_search_slot(NULL, tree_root, location, path, 0, 0);
 838         if (ret != 0) {
 839                 if (ret > 0)
 840                         ret = -ENOENT;
 841                 goto out;
 842         }
 843         l = path->nodes[0];
 844         read_extent_buffer(l, &root->root_item,
 845                btrfs_item_ptr_offset(l, path->slots[0]),
 846                sizeof(root->root_item));
 847         memcpy(&root->root_key, location, sizeof(*location));
 848         ret = 0;
 849 out:
 850         btrfs_release_path(root, path);
 851         btrfs_free_path(path);
 852         if (ret) {
 853                 kfree(root);
 854                 return ERR_PTR(ret);
 855         }
 856         blocksize = btrfs_level_size(root, btrfs_root_level(&root->root_item));
 857         root->node = read_tree_block(root, btrfs_root_bytenr(&root->root_item),
 858                                      blocksize, 0);
 859         BUG_ON(!root->node);
 860 insert:
 861         root->ref_cows = 1;
 862         ret = btrfs_find_highest_inode(root, &highest_inode);
 863         if (ret == 0) {
 864                 root->highest_inode = highest_inode;
 865                 root->last_inode_alloc = highest_inode;
 866         }
 867         return root;
 868 }
 869
 870 struct btrfs_root *btrfs_lookup_fs_root(struct btrfs_fs_info *fs_info,
 871                                         u64 root_objectid)
 872 {
 873         struct btrfs_root *root;
 874
 875         if (root_objectid == BTRFS_ROOT_TREE_OBJECTID)
 876                 return fs_info->tree_root;
 877         if (root_objectid == BTRFS_EXTENT_TREE_OBJECTID)
 878                 return fs_info->extent_root;
 879
 880         root = radix_tree_lookup(&fs_info->fs_roots_radix,
 881                                  (unsigned long)root_objectid);
 882         return root;
 883 }
 884
 885 struct btrfs_root *btrfs_read_fs_root_no_name(struct btrfs_fs_info *fs_info,
 886                                               struct btrfs_key *location)
 887 {
 888         struct btrfs_root *root;
 889         int ret;
 890
 891         if (location->objectid == BTRFS_ROOT_TREE_OBJECTID)
 892                 return fs_info->tree_root;
 893         if (location->objectid == BTRFS_EXTENT_TREE_OBJECTID)
 894                 return fs_info->extent_root;
 895         if (location->objectid == BTRFS_CHUNK_TREE_OBJECTID)
 896                 return fs_info->chunk_root;
 897         if (location->objectid == BTRFS_DEV_TREE_OBJECTID)
 898                 return fs_info->dev_root;
 899
 900         root = radix_tree_lookup(&fs_info->fs_roots_radix,
 901                                  (unsigned long)location->objectid);
 902         if (root)
 903                 return root;
 904
 905         root = btrfs_read_fs_root_no_radix(fs_info, location);
 906         if (IS_ERR(root))
 907                 return root;
 908         ret = radix_tree_insert(&fs_info->fs_roots_radix,
 909                                 (unsigned long)root->root_key.objectid,
 910                                 root);
 911         if (ret) {
 912                 free_extent_buffer(root->node);
 913                 kfree(root);
 914                 return ERR_PTR(ret);
 915         }
 916         ret = btrfs_find_dead_roots(fs_info->tree_root,
 917                                     root->root_key.objectid, root);
 918         BUG_ON(ret);
 919
 920         return root;
 921 }
 922
 923 struct btrfs_root *btrfs_read_fs_root(struct btrfs_fs_info *fs_info,
 924                                       struct btrfs_key *location,
 925                                       const char *name, int namelen)
 926 {
 927         struct btrfs_root *root;
 928         int ret;
 929
 930         root = btrfs_read_fs_root_no_name(fs_info, location);
 931         if (!root)
 932                 return NULL;
 933
 934         if (root->in_sysfs)
 935                 return root;
 936
 937         ret = btrfs_set_root_name(root, name, namelen);
 938         if (ret) {
 939                 free_extent_buffer(root->node);
 940                 kfree(root);
 941                 return ERR_PTR(ret);
 942         }
 943
 944         ret = btrfs_sysfs_add_root(root);
 945         if (ret) {
 946                 free_extent_buffer(root->node);
 947                 kfree(root->name);
 948                 kfree(root);
 949                 return ERR_PTR(ret);
 950         }
 951         root->in_sysfs = 1;
 952         return root;
 953 }
 954 #if 0
 955 static int add_hasher(struct btrfs_fs_info *info, char *type) {
 956         struct btrfs_hasher *hasher;
 957
 958         hasher = kmalloc(sizeof(*hasher), GFP_NOFS);
 959         if (!hasher)
 960                 return -ENOMEM;
 961         hasher->hash_tfm = crypto_alloc_hash(type, 0, CRYPTO_ALG_ASYNC);
 962         if (!hasher->hash_tfm) {
 963                 kfree(hasher);
 964                 return -EINVAL;
 965         }
 966         spin_lock(&info->hash_lock);
 967         list_add(&hasher->list, &info->hashers);
 968         spin_unlock(&info->hash_lock);
 969         return 0;
 970 }
 971 #endif
 972
 973 static int btrfs_congested_fn(void *congested_data, int bdi_bits)
 974 {
 975         struct btrfs_fs_info *info = (struct btrfs_fs_info *)congested_data;
 976         int ret = 0;
 977         struct list_head *cur;
 978         struct btrfs_device *device;
 979         struct backing_dev_info *bdi;
 980
 981         if ((bdi_bits & (1 << BDI_write_congested)) &&
 982             btrfs_congested_async(info, 0))
 983                 return 1;
 984
 985         list_for_each(cur, &info->fs_devices->devices) {
 986                 device = list_entry(cur, struct btrfs_device, dev_list);
 987                 if (!device->bdev)
 988                         continue;
 989                 bdi = blk_get_backing_dev_info(device->bdev);
 990                 if (bdi && bdi_congested(bdi, bdi_bits)) {
 991                         ret = 1;
 992                         break;
 993                 }
 994         }
 995         return ret;
 996 }
 997
 998 /*
 999  * this unplugs every device on the box, and it is only used when page
1000  * is null
1001  */
1002 static void __unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
1003 {
1004         struct list_head *cur;
1005         struct btrfs_device *device;
1006         struct btrfs_fs_info *info;
1007
1008         info = (struct btrfs_fs_info *)bdi->unplug_io_data;
1009         list_for_each(cur, &info->fs_devices->devices) {
1010                 device = list_entry(cur, struct btrfs_device, dev_list);
1011                 bdi = blk_get_backing_dev_info(device->bdev);
1012                 if (bdi->unplug_io_fn) {
1013                         bdi->unplug_io_fn(bdi, page);
1014                 }
1015         }
1016 }
1017
1018 void btrfs_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
1019 {
1020         struct inode *inode;
1021         struct extent_map_tree *em_tree;
1022         struct extent_map *em;
1023         struct address_space *mapping;
1024         u64 offset;
1025
1026         /* the generic O_DIRECT read code does this */
1027         if (!page) {
1028                 __unplug_io_fn(bdi, page);
1029                 return;
1030         }
1031
1032         /*
1033          * page->mapping may change at any time.  Get a consistent copy
1034          * and use that for everything below
1035          */
1036         smp_mb();
1037         mapping = page->mapping;
1038         if (!mapping)
1039                 return;
1040
1041         inode = mapping->host;
1042         offset = page_offset(page);
1043
1044         em_tree = &BTRFS_I(inode)->extent_tree;
1045         spin_lock(&em_tree->lock);
1046         em = lookup_extent_mapping(em_tree, offset, PAGE_CACHE_SIZE);
1047         spin_unlock(&em_tree->lock);
1048         if (!em) {
1049                 __unplug_io_fn(bdi, page);
1050                 return;
1051         }
1052
1053         if (em->block_start >= EXTENT_MAP_LAST_BYTE) {
1054                 free_extent_map(em);
1055                 __unplug_io_fn(bdi, page);
1056                 return;
1057         }
1058         offset = offset - em->start;
1059         btrfs_unplug_page(&BTRFS_I(inode)->root->fs_info->mapping_tree,
1060                           em->block_start + offset, page);
1061         free_extent_map(em);
1062 }
1063
1064 static int setup_bdi(struct btrfs_fs_info *info, struct backing_dev_info *bdi)
1065 {
1066 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,23)
1067         bdi_init(bdi);
1068 #endif
1069         bdi->ra_pages   = default_backing_dev_info.ra_pages;
1070         bdi->state              = 0;
1071         bdi->capabilities       = default_backing_dev_info.capabilities;
1072         bdi->unplug_io_fn       = btrfs_unplug_io_fn;
1073         bdi->unplug_io_data     = info;
1074         bdi->congested_fn       = btrfs_congested_fn;
1075         bdi->congested_data     = info;
1076         return 0;
1077 }
1078
1079 static int bio_ready_for_csum(struct bio *bio)
1080 {
1081         u64 length = 0;
1082         u64 buf_len = 0;
1083         u64 start = 0;
1084         struct page *page;
1085         struct extent_io_tree *io_tree = NULL;
1086         struct btrfs_fs_info *info = NULL;
1087         struct bio_vec *bvec;
1088         int i;
1089         int ret;
1090
1091         bio_for_each_segment(bvec, bio, i) {
1092                 page = bvec->bv_page;
1093                 if (page->private == EXTENT_PAGE_PRIVATE) {
1094                         length += bvec->bv_len;
1095                         continue;
1096                 }
1097                 if (!page->private) {
1098                         length += bvec->bv_len;
1099                         continue;
1100                 }
1101                 length = bvec->bv_len;
1102                 buf_len = page->private >> 2;
1103                 start = page_offset(page) + bvec->bv_offset;
1104                 io_tree = &BTRFS_I(page->mapping->host)->io_tree;
1105                 info = BTRFS_I(page->mapping->host)->root->fs_info;
1106         }
1107         /* are we fully contained in this bio? */
1108         if (buf_len <= length)
1109                 return 1;
1110
1111         ret = extent_range_uptodate(io_tree, start + length,
1112                                     start + buf_len - 1);
1113         if (ret == 1)
1114                 return ret;
1115         return ret;
1116 }
1117
1118 /*
1119  * called by the kthread helper functions to finally call the bio end_io
1120  * functions.  This is where read checksum verification actually happens
1121  */
1122 static void end_workqueue_fn(struct btrfs_work *work)
1123 {
1124         struct bio *bio;
1125         struct end_io_wq *end_io_wq;
1126         struct btrfs_fs_info *fs_info;
1127         int error;
1128
1129         end_io_wq = container_of(work, struct end_io_wq, work);
1130         bio = end_io_wq->bio;
1131         fs_info = end_io_wq->info;
1132
1133         /* metadata bios are special because the whole tree block must
1134          * be checksummed at once.  This makes sure the entire block is in
1135          * ram and up to date before trying to verify things.  For
1136          * blocksize <= pagesize, it is basically a noop
1137          */
1138         if (end_io_wq->metadata && !bio_ready_for_csum(bio)) {
1139                 btrfs_queue_worker(&fs_info->endio_workers,
1140                                    &end_io_wq->work);
1141                 return;
1142         }
1143         error = end_io_wq->error;
1144         bio->bi_private = end_io_wq->private;
1145         bio->bi_end_io = end_io_wq->end_io;
1146         kfree(end_io_wq);
1147 #if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
1148         bio_endio(bio, bio->bi_size, error);
1149 #else
1150         bio_endio(bio, error);
1151 #endif
1152 }
1153
1154 static int cleaner_kthread(void *arg)
1155 {
1156         struct btrfs_root *root = arg;
1157
1158         do {
1159                 smp_mb();
1160                 if (root->fs_info->closing)
1161                         break;
1162
1163                 vfs_check_frozen(root->fs_info->sb, SB_FREEZE_WRITE);
1164                 mutex_lock(&root->fs_info->cleaner_mutex);
1165                 btrfs_clean_old_snapshots(root);
1166                 mutex_unlock(&root->fs_info->cleaner_mutex);
1167
1168                 if (freezing(current)) {
1169                         refrigerator();
1170                 } else {
1171                         smp_mb();
1172                         if (root->fs_info->closing)
1173                                 break;
1174                         set_current_state(TASK_INTERRUPTIBLE);
1175                         schedule();
1176                         __set_current_state(TASK_RUNNING);
1177                 }
1178         } while (!kthread_should_stop());
1179         return 0;
1180 }
1181
1182 static int transaction_kthread(void *arg)
1183 {
1184         struct btrfs_root *root = arg;
1185         struct btrfs_trans_handle *trans;
1186         struct btrfs_transaction *cur;
1187         unsigned long now;
1188         unsigned long delay;
1189         int ret;
1190
1191         do {
1192                 smp_mb();
1193                 if (root->fs_info->closing)
1194                         break;
1195
1196                 delay = HZ * 30;
1197                 vfs_check_frozen(root->fs_info->sb, SB_FREEZE_WRITE);
1198                 mutex_lock(&root->fs_info->transaction_kthread_mutex);
1199
1200                 if (root->fs_info->total_ref_cache_size > 20 * 1024 * 1024) {
1201                         printk("btrfs: total reference cache size %Lu\n",
1202                                 root->fs_info->total_ref_cache_size);
1203                 }
1204
1205                 mutex_lock(&root->fs_info->trans_mutex);
1206                 cur = root->fs_info->running_transaction;
1207                 if (!cur) {
1208                         mutex_unlock(&root->fs_info->trans_mutex);
1209                         goto sleep;
1210                 }
1211
1212                 now = get_seconds();
1213                 if (now < cur->start_time || now - cur->start_time < 30) {
1214                         mutex_unlock(&root->fs_info->trans_mutex);
1215                         delay = HZ * 5;
1216                         goto sleep;
1217                 }
1218                 mutex_unlock(&root->fs_info->trans_mutex);
1219                 trans = btrfs_start_transaction(root, 1);
1220                 ret = btrfs_commit_transaction(trans, root);
1221 sleep:
1222                 wake_up_process(root->fs_info->cleaner_kthread);
1223                 mutex_unlock(&root->fs_info->transaction_kthread_mutex);
1224
1225                 if (freezing(current)) {
1226                         refrigerator();
1227                 } else {
1228                         if (root->fs_info->closing)
1229                                 break;
1230                         set_current_state(TASK_INTERRUPTIBLE);
1231                         schedule_timeout(delay);
1232                         __set_current_state(TASK_RUNNING);
1233                 }
1234         } while (!kthread_should_stop());
1235         return 0;
1236 }
1237
1238 struct btrfs_root *open_ctree(struct super_block *sb,
1239                               struct btrfs_fs_devices *fs_devices,
1240                               char *options)
1241 {
1242         u32 sectorsize;
1243         u32 nodesize;
1244         u32 leafsize;
1245         u32 blocksize;
1246         u32 stripesize;
1247         struct buffer_head *bh;
1248         struct btrfs_root *extent_root = kmalloc(sizeof(struct btrfs_root),
1249                                                  GFP_NOFS);
1250         struct btrfs_root *tree_root = kmalloc(sizeof(struct btrfs_root),
1251                                                GFP_NOFS);
1252         struct btrfs_fs_info *fs_info = kzalloc(sizeof(*fs_info),
1253                                                 GFP_NOFS);
1254         struct btrfs_root *chunk_root = kmalloc(sizeof(struct btrfs_root),
1255                                                 GFP_NOFS);
1256         struct btrfs_root *dev_root = kmalloc(sizeof(struct btrfs_root),
1257                                               GFP_NOFS);
1258         int ret;
1259         int err = -EINVAL;
1260
1261         struct btrfs_super_block *disk_super;
1262
1263         if (!extent_root || !tree_root || !fs_info) {
1264                 err = -ENOMEM;
1265                 goto fail;
1266         }
1267         INIT_RADIX_TREE(&fs_info->fs_roots_radix, GFP_NOFS);
1268         INIT_LIST_HEAD(&fs_info->trans_list);
1269         INIT_LIST_HEAD(&fs_info->dead_roots);
1270         INIT_LIST_HEAD(&fs_info->hashers);
1271         INIT_LIST_HEAD(&fs_info->delalloc_inodes);
1272         spin_lock_init(&fs_info->hash_lock);
1273         spin_lock_init(&fs_info->delalloc_lock);
1274         spin_lock_init(&fs_info->new_trans_lock);
1275         spin_lock_init(&fs_info->ref_cache_lock);
1276
1277         init_completion(&fs_info->kobj_unregister);
1278         fs_info->tree_root = tree_root;
1279         fs_info->extent_root = extent_root;
1280         fs_info->chunk_root = chunk_root;
1281         fs_info->dev_root = dev_root;
1282         fs_info->fs_devices = fs_devices;
1283         INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);
1284         INIT_LIST_HEAD(&fs_info->space_info);
1285         btrfs_mapping_init(&fs_info->mapping_tree);
1286         atomic_set(&fs_info->nr_async_submits, 0);
1287         atomic_set(&fs_info->nr_async_bios, 0);
1288         atomic_set(&fs_info->throttles, 0);
1289         atomic_set(&fs_info->throttle_gen, 0);
1290         fs_info->sb = sb;
1291         fs_info->max_extent = (u64)-1;
1292         fs_info->max_inline = 8192 * 1024;
1293         setup_bdi(fs_info, &fs_info->bdi);
1294         fs_info->btree_inode = new_inode(sb);
1295         fs_info->btree_inode->i_ino = 1;
1296         fs_info->btree_inode->i_nlink = 1;
1297         fs_info->thread_pool_size = min(num_online_cpus() + 2, 8);
1298
1299         INIT_LIST_HEAD(&fs_info->ordered_extents);
1300         spin_lock_init(&fs_info->ordered_extent_lock);
1301
1302         sb->s_blocksize = 4096;
1303         sb->s_blocksize_bits = blksize_bits(4096);
1304
1305         /*
1306          * we set the i_size on the btree inode to the max possible int.
1307          * the real end of the address space is determined by all of
1308          * the devices in the system
1309          */
1310         fs_info->btree_inode->i_size = OFFSET_MAX;
1311         fs_info->btree_inode->i_mapping->a_ops = &btree_aops;
1312         fs_info->btree_inode->i_mapping->backing_dev_info = &fs_info->bdi;
1313
1314         extent_io_tree_init(&BTRFS_I(fs_info->btree_inode)->io_tree,
1315                              fs_info->btree_inode->i_mapping,
1316                              GFP_NOFS);
1317         extent_map_tree_init(&BTRFS_I(fs_info->btree_inode)->extent_tree,
1318                              GFP_NOFS);
1319
1320         BTRFS_I(fs_info->btree_inode)->io_tree.ops = &btree_extent_io_ops;
1321
1322         extent_io_tree_init(&fs_info->free_space_cache,
1323                              fs_info->btree_inode->i_mapping, GFP_NOFS);
1324         extent_io_tree_init(&fs_info->block_group_cache,
1325                              fs_info->btree_inode->i_mapping, GFP_NOFS);
1326         extent_io_tree_init(&fs_info->pinned_extents,
1327                              fs_info->btree_inode->i_mapping, GFP_NOFS);
1328         extent_io_tree_init(&fs_info->pending_del,
1329                              fs_info->btree_inode->i_mapping, GFP_NOFS);
1330         extent_io_tree_init(&fs_info->extent_ins,
1331                              fs_info->btree_inode->i_mapping, GFP_NOFS);
1332         fs_info->do_barriers = 1;
1333
1334         BTRFS_I(fs_info->btree_inode)->root = tree_root;
1335         memset(&BTRFS_I(fs_info->btree_inode)->location, 0,
1336                sizeof(struct btrfs_key));
1337         insert_inode_hash(fs_info->btree_inode);
1338         mapping_set_gfp_mask(fs_info->btree_inode->i_mapping, GFP_NOFS);
1339
1340         mutex_init(&fs_info->trans_mutex);
1341         mutex_init(&fs_info->drop_mutex);
1342         mutex_init(&fs_info->alloc_mutex);
1343         mutex_init(&fs_info->chunk_mutex);
1344         mutex_init(&fs_info->transaction_kthread_mutex);
1345         mutex_init(&fs_info->cleaner_mutex);
1346         mutex_init(&fs_info->volume_mutex);
1347         init_waitqueue_head(&fs_info->transaction_throttle);
1348         init_waitqueue_head(&fs_info->transaction_wait);
1349         init_waitqueue_head(&fs_info->async_submit_wait);
1350
1351 #if 0
1352         ret = add_hasher(fs_info, "crc32c");
1353         if (ret) {
1354                 printk("btrfs: failed hash setup, modprobe cryptomgr?\n");
1355                 err = -ENOMEM;
1356                 goto fail_iput;
1357         }
1358 #endif
1359         __setup_root(4096, 4096, 4096, 4096, tree_root,
1360                      fs_info, BTRFS_ROOT_TREE_OBJECTID);
1361
1362
1363         bh = __bread(fs_devices->latest_bdev,
1364                      BTRFS_SUPER_INFO_OFFSET / 4096, 4096);
1365         if (!bh)
1366                 goto fail_iput;
1367
1368         memcpy(&fs_info->super_copy, bh->b_data, sizeof(fs_info->super_copy));
1369         brelse(bh);
1370
1371         memcpy(fs_info->fsid, fs_info->super_copy.fsid, BTRFS_FSID_SIZE);
1372
1373         disk_super = &fs_info->super_copy;
1374         if (!btrfs_super_root(disk_super))
1375                 goto fail_sb_buffer;
1376
1377         err = btrfs_parse_options(tree_root, options);
1378         if (err)
1379                 goto fail_sb_buffer;
1380
1381         /*
1382          * we need to start all the end_io workers up front because the
1383          * queue work function gets called at interrupt time, and so it
1384          * cannot dynamically grow.
1385          */
1386         btrfs_init_workers(&fs_info->workers, "worker",
1387                            fs_info->thread_pool_size);
1388         btrfs_init_workers(&fs_info->submit_workers, "submit",
1389                            min_t(u64, fs_devices->num_devices,
1390                            fs_info->thread_pool_size));
1391
1392         /* a higher idle thresh on the submit workers makes it much more
1393          * likely that bios will be send down in a sane order to the
1394          * devices
1395          */
1396         fs_info->submit_workers.idle_thresh = 64;
1397
1398         /* fs_info->workers is responsible for checksumming file data
1399          * blocks and metadata.  Using a larger idle thresh allows each
1400          * worker thread to operate on things in roughly the order they
1401          * were sent by the writeback daemons, improving overall locality
1402          * of the IO going down the pipe.
1403          */
1404         fs_info->workers.idle_thresh = 128;
1405
1406         btrfs_init_workers(&fs_info->fixup_workers, "fixup", 1);
1407         btrfs_init_workers(&fs_info->endio_workers, "endio",
1408                            fs_info->thread_pool_size);
1409         btrfs_init_workers(&fs_info->endio_write_workers, "endio-write",
1410                            fs_info->thread_pool_size);
1411
1412         /*
1413          * endios are largely parallel and should have a very
1414          * low idle thresh
1415          */
1416         fs_info->endio_workers.idle_thresh = 4;
1417         fs_info->endio_write_workers.idle_thresh = 4;
1418
1419         btrfs_start_workers(&fs_info->workers, 1);
1420         btrfs_start_workers(&fs_info->submit_workers, 1);
1421         btrfs_start_workers(&fs_info->fixup_workers, 1);
1422         btrfs_start_workers(&fs_info->endio_workers, fs_info->thread_pool_size);
1423         btrfs_start_workers(&fs_info->endio_write_workers,
1424                             fs_info->thread_pool_size);
1425
1426         err = -EINVAL;
1427         if (btrfs_super_num_devices(disk_super) > fs_devices->open_devices) {
1428                 printk("Btrfs: wanted %llu devices, but found %llu\n",
1429                        (unsigned long long)btrfs_super_num_devices(disk_super),
1430                        (unsigned long long)fs_devices->open_devices);
1431                 if (btrfs_test_opt(tree_root, DEGRADED))
1432                         printk("continuing in degraded mode\n");
1433                 else {
1434                         goto fail_sb_buffer;
1435                 }
1436         }
1437
1438         fs_info->bdi.ra_pages *= btrfs_super_num_devices(disk_super);
1439
1440         nodesize = btrfs_super_nodesize(disk_super);
1441         leafsize = btrfs_super_leafsize(disk_super);
1442         sectorsize = btrfs_super_sectorsize(disk_super);
1443         stripesize = btrfs_super_stripesize(disk_super);
1444         tree_root->nodesize = nodesize;
1445         tree_root->leafsize = leafsize;
1446         tree_root->sectorsize = sectorsize;
1447         tree_root->stripesize = stripesize;
1448
1449         sb->s_blocksize = sectorsize;
1450         sb->s_blocksize_bits = blksize_bits(sectorsize);
1451
1452         if (strncmp((char *)(&disk_super->magic), BTRFS_MAGIC,
1453                     sizeof(disk_super->magic))) {
1454                 printk("btrfs: valid FS not found on %s\n", sb->s_id);
1455                 goto fail_sb_buffer;
1456         }
1457
1458         mutex_lock(&fs_info->chunk_mutex);
1459         ret = btrfs_read_sys_array(tree_root);
1460         mutex_unlock(&fs_info->chunk_mutex);
1461         if (ret) {
1462                 printk("btrfs: failed to read the system array on %s\n",
1463                        sb->s_id);
1464                 goto fail_sys_array;
1465         }
1466
1467         blocksize = btrfs_level_size(tree_root,
1468                                      btrfs_super_chunk_root_level(disk_super));
1469
1470         __setup_root(nodesize, leafsize, sectorsize, stripesize,
1471                      chunk_root, fs_info, BTRFS_CHUNK_TREE_OBJECTID);
1472
1473         chunk_root->node = read_tree_block(chunk_root,
1474                                            btrfs_super_chunk_root(disk_super),
1475                                            blocksize, 0);
1476         BUG_ON(!chunk_root->node);
1477
1478         read_extent_buffer(chunk_root->node, fs_info->chunk_tree_uuid,
1479                  (unsigned long)btrfs_header_chunk_tree_uuid(chunk_root->node),
1480                  BTRFS_UUID_SIZE);
1481
1482         mutex_lock(&fs_info->chunk_mutex);
1483         ret = btrfs_read_chunk_tree(chunk_root);
1484         mutex_unlock(&fs_info->chunk_mutex);
1485         BUG_ON(ret);
1486
1487         btrfs_close_extra_devices(fs_devices);
1488
1489         blocksize = btrfs_level_size(tree_root,
1490                                      btrfs_super_root_level(disk_super));
1491
1492
1493         tree_root->node = read_tree_block(tree_root,
1494                                           btrfs_super_root(disk_super),
1495                                           blocksize, 0);
1496         if (!tree_root->node)
1497                 goto fail_sb_buffer;
1498
1499
1500         ret = find_and_setup_root(tree_root, fs_info,
1501                                   BTRFS_EXTENT_TREE_OBJECTID, extent_root);
1502         if (ret)
1503                 goto fail_tree_root;
1504         extent_root->track_dirty = 1;
1505
1506         ret = find_and_setup_root(tree_root, fs_info,
1507                                   BTRFS_DEV_TREE_OBJECTID, dev_root);
1508         dev_root->track_dirty = 1;
1509
1510         if (ret)
1511                 goto fail_extent_root;
1512
1513         btrfs_read_block_groups(extent_root);
1514
1515         fs_info->generation = btrfs_super_generation(disk_super) + 1;
1516         fs_info->data_alloc_profile = (u64)-1;
1517         fs_info->metadata_alloc_profile = (u64)-1;
1518         fs_info->system_alloc_profile = fs_info->metadata_alloc_profile;
1519         fs_info->cleaner_kthread = kthread_run(cleaner_kthread, tree_root,
1520                                                "btrfs-cleaner");
1521         if (!fs_info->cleaner_kthread)
1522                 goto fail_extent_root;
1523
1524         fs_info->transaction_kthread = kthread_run(transaction_kthread,
1525                                                    tree_root,
1526                                                    "btrfs-transaction");
1527         if (!fs_info->transaction_kthread)
1528                 goto fail_cleaner;
1529
1530
1531         return tree_root;
1532
1533 fail_cleaner:
1534         kthread_stop(fs_info->cleaner_kthread);
1535 fail_extent_root:
1536         free_extent_buffer(extent_root->node);
1537 fail_tree_root:
1538         free_extent_buffer(tree_root->node);
1539 fail_sys_array:
1540 fail_sb_buffer:
1541         btrfs_stop_workers(&fs_info->fixup_workers);
1542         btrfs_stop_workers(&fs_info->workers);
1543         btrfs_stop_workers(&fs_info->endio_workers);
1544         btrfs_stop_workers(&fs_info->endio_write_workers);
1545         btrfs_stop_workers(&fs_info->submit_workers);
1546 fail_iput:
1547         iput(fs_info->btree_inode);
1548 fail:
1549         btrfs_close_devices(fs_info->fs_devices);
1550         btrfs_mapping_tree_free(&fs_info->mapping_tree);
1551
1552         kfree(extent_root);
1553         kfree(tree_root);
1554 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,23)
1555         bdi_destroy(&fs_info->bdi);
1556 #endif
1557         kfree(fs_info);
1558         return ERR_PTR(err);
1559 }
1560
1561 static void btrfs_end_buffer_write_sync(struct buffer_head *bh, int uptodate)
1562 {
1563         char b[BDEVNAME_SIZE];
1564
1565         if (uptodate) {
1566                 set_buffer_uptodate(bh);
1567         } else {
1568                 if (!buffer_eopnotsupp(bh) && printk_ratelimit()) {
1569                         printk(KERN_WARNING "lost page write due to "
1570                                         "I/O error on %s\n",
1571                                        bdevname(bh->b_bdev, b));
1572                 }
1573                 /* note, we dont' set_buffer_write_io_error because we have
1574                  * our own ways of dealing with the IO errors
1575                  */
1576                 clear_buffer_uptodate(bh);
1577         }
1578         unlock_buffer(bh);
1579         put_bh(bh);
1580 }
1581
1582 int write_all_supers(struct btrfs_root *root)
1583 {
1584         struct list_head *cur;
1585         struct list_head *head = &root->fs_info->fs_devices->devices;
1586         struct btrfs_device *dev;
1587         struct btrfs_super_block *sb;
1588         struct btrfs_dev_item *dev_item;
1589         struct buffer_head *bh;
1590         int ret;
1591         int do_barriers;
1592         int max_errors;
1593         int total_errors = 0;
1594         u32 crc;
1595         u64 flags;
1596
1597         max_errors = btrfs_super_num_devices(&root->fs_info->super_copy) - 1;
1598         do_barriers = !btrfs_test_opt(root, NOBARRIER);
1599
1600         sb = &root->fs_info->super_for_commit;
1601         dev_item = &sb->dev_item;
1602         list_for_each(cur, head) {
1603                 dev = list_entry(cur, struct btrfs_device, dev_list);
1604                 if (!dev->bdev) {
1605                         total_errors++;
1606                         continue;
1607                 }
1608                 if (!dev->in_fs_metadata)
1609                         continue;
1610
1611                 btrfs_set_stack_device_type(dev_item, dev->type);
1612                 btrfs_set_stack_device_id(dev_item, dev->devid);
1613                 btrfs_set_stack_device_total_bytes(dev_item, dev->total_bytes);
1614                 btrfs_set_stack_device_bytes_used(dev_item, dev->bytes_used);
1615                 btrfs_set_stack_device_io_align(dev_item, dev->io_align);
1616                 btrfs_set_stack_device_io_width(dev_item, dev->io_width);
1617                 btrfs_set_stack_device_sector_size(dev_item, dev->sector_size);
1618                 memcpy(dev_item->uuid, dev->uuid, BTRFS_UUID_SIZE);
1619                 flags = btrfs_super_flags(sb);
1620                 btrfs_set_super_flags(sb, flags | BTRFS_HEADER_FLAG_WRITTEN);
1621
1622
1623                 crc = ~(u32)0;
1624                 crc = btrfs_csum_data(root, (char *)sb + BTRFS_CSUM_SIZE, crc,
1625                                       BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE);
1626                 btrfs_csum_final(crc, sb->csum);
1627
1628                 bh = __getblk(dev->bdev, BTRFS_SUPER_INFO_OFFSET / 4096,
1629                               BTRFS_SUPER_INFO_SIZE);
1630
1631                 memcpy(bh->b_data, sb, BTRFS_SUPER_INFO_SIZE);
1632                 dev->pending_io = bh;
1633
1634                 get_bh(bh);
1635                 set_buffer_uptodate(bh);
1636                 lock_buffer(bh);
1637                 bh->b_end_io = btrfs_end_buffer_write_sync;
1638
1639                 if (do_barriers && dev->barriers) {
1640                         ret = submit_bh(WRITE_BARRIER, bh);
1641                         if (ret == -EOPNOTSUPP) {
1642                                 printk("btrfs: disabling barriers on dev %s\n",
1643                                        dev->name);
1644                                 set_buffer_uptodate(bh);
1645                                 dev->barriers = 0;
1646                                 get_bh(bh);
1647                                 lock_buffer(bh);
1648                                 ret = submit_bh(WRITE, bh);
1649                         }
1650                 } else {
1651                         ret = submit_bh(WRITE, bh);
1652                 }
1653                 if (ret)
1654                         total_errors++;
1655         }
1656         if (total_errors > max_errors) {
1657                 printk("btrfs: %d errors while writing supers\n", total_errors);
1658                 BUG();
1659         }
1660         total_errors = 0;
1661
1662         list_for_each(cur, head) {
1663                 dev = list_entry(cur, struct btrfs_device, dev_list);
1664                 if (!dev->bdev)
1665                         continue;
1666                 if (!dev->in_fs_metadata)
1667                         continue;
1668
1669                 BUG_ON(!dev->pending_io);
1670                 bh = dev->pending_io;
1671                 wait_on_buffer(bh);
1672                 if (!buffer_uptodate(dev->pending_io)) {
1673                         if (do_barriers && dev->barriers) {
1674                                 printk("btrfs: disabling barriers on dev %s\n",
1675                                        dev->name);
1676                                 set_buffer_uptodate(bh);
1677                                 get_bh(bh);
1678                                 lock_buffer(bh);
1679                                 dev->barriers = 0;
1680                                 ret = submit_bh(WRITE, bh);
1681                                 BUG_ON(ret);
1682                                 wait_on_buffer(bh);
1683                                 if (!buffer_uptodate(bh))
1684                                         total_errors++;
1685                         } else {
1686                                 total_errors++;
1687                         }
1688
1689                 }
1690                 dev->pending_io = NULL;
1691                 brelse(bh);
1692         }
1693         if (total_errors > max_errors) {
1694                 printk("btrfs: %d errors while writing supers\n", total_errors);
1695                 BUG();
1696         }
1697         return 0;
1698 }
1699
1700 int write_ctree_super(struct btrfs_trans_handle *trans, struct btrfs_root
1701                       *root)
1702 {
1703         int ret;
1704
1705         ret = write_all_supers(root);
1706         return ret;
1707 }
1708
1709 int btrfs_free_fs_root(struct btrfs_fs_info *fs_info, struct btrfs_root *root)
1710 {
1711         radix_tree_delete(&fs_info->fs_roots_radix,
1712                           (unsigned long)root->root_key.objectid);
1713         if (root->in_sysfs)
1714                 btrfs_sysfs_del_root(root);
1715         if (root->inode)
1716                 iput(root->inode);
1717         if (root->node)
1718                 free_extent_buffer(root->node);
1719         if (root->commit_root)
1720                 free_extent_buffer(root->commit_root);
1721         if (root->name)
1722                 kfree(root->name);
1723         kfree(root);
1724         return 0;
1725 }
1726
1727 static int del_fs_roots(struct btrfs_fs_info *fs_info)
1728 {
1729         int ret;
1730         struct btrfs_root *gang[8];
1731         int i;
1732
1733         while(1) {
1734                 ret = radix_tree_gang_lookup(&fs_info->fs_roots_radix,
1735                                              (void **)gang, 0,
1736                                              ARRAY_SIZE(gang));
1737                 if (!ret)
1738                         break;
1739                 for (i = 0; i < ret; i++)
1740                         btrfs_free_fs_root(fs_info, gang[i]);
1741         }
1742         return 0;
1743 }
1744
1745 int close_ctree(struct btrfs_root *root)
1746 {
1747         int ret;
1748         struct btrfs_trans_handle *trans;
1749         struct btrfs_fs_info *fs_info = root->fs_info;
1750
1751         fs_info->closing = 1;
1752         smp_mb();
1753
1754         kthread_stop(root->fs_info->transaction_kthread);
1755         kthread_stop(root->fs_info->cleaner_kthread);
1756
1757         btrfs_clean_old_snapshots(root);
1758         trans = btrfs_start_transaction(root, 1);
1759         ret = btrfs_commit_transaction(trans, root);
1760         /* run commit again to  drop the original snapshot */
1761         trans = btrfs_start_transaction(root, 1);
1762         btrfs_commit_transaction(trans, root);
1763         ret = btrfs_write_and_wait_transaction(NULL, root);
1764         BUG_ON(ret);
1765
1766         write_ctree_super(NULL, root);
1767
1768         if (fs_info->delalloc_bytes) {
1769                 printk("btrfs: at unmount delalloc count %Lu\n",
1770                        fs_info->delalloc_bytes);
1771         }
1772         if (fs_info->total_ref_cache_size) {
1773                 printk("btrfs: at umount reference cache size %Lu\n",
1774                         fs_info->total_ref_cache_size);
1775         }
1776
1777         if (fs_info->extent_root->node)
1778                 free_extent_buffer(fs_info->extent_root->node);
1779
1780         if (fs_info->tree_root->node)
1781                 free_extent_buffer(fs_info->tree_root->node);
1782
1783         if (root->fs_info->chunk_root->node);
1784                 free_extent_buffer(root->fs_info->chunk_root->node);
1785
1786         if (root->fs_info->dev_root->node);
1787                 free_extent_buffer(root->fs_info->dev_root->node);
1788
1789         btrfs_free_block_groups(root->fs_info);
1790         fs_info->closing = 2;
1791         del_fs_roots(fs_info);
1792
1793         filemap_write_and_wait(fs_info->btree_inode->i_mapping);
1794
1795         truncate_inode_pages(fs_info->btree_inode->i_mapping, 0);
1796
1797         btrfs_stop_workers(&fs_info->fixup_workers);
1798         btrfs_stop_workers(&fs_info->workers);
1799         btrfs_stop_workers(&fs_info->endio_workers);
1800         btrfs_stop_workers(&fs_info->endio_write_workers);
1801         btrfs_stop_workers(&fs_info->submit_workers);
1802
1803         iput(fs_info->btree_inode);
1804 #if 0
1805         while(!list_empty(&fs_info->hashers)) {
1806                 struct btrfs_hasher *hasher;
1807                 hasher = list_entry(fs_info->hashers.next, struct btrfs_hasher,
1808                                     hashers);
1809                 list_del(&hasher->hashers);
1810                 crypto_free_hash(&fs_info->hash_tfm);
1811                 kfree(hasher);
1812         }
1813 #endif
1814         btrfs_close_devices(fs_info->fs_devices);
1815         btrfs_mapping_tree_free(&fs_info->mapping_tree);
1816
1817 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,23)
1818         bdi_destroy(&fs_info->bdi);
1819 #endif
1820
1821         kfree(fs_info->extent_root);
1822         kfree(fs_info->tree_root);
1823         kfree(fs_info->chunk_root);
1824         kfree(fs_info->dev_root);
1825         return 0;
1826 }
1827
1828 int btrfs_buffer_uptodate(struct extent_buffer *buf, u64 parent_transid)
1829 {
1830         int ret;
1831         struct inode *btree_inode = buf->first_page->mapping->host;
1832
1833         ret = extent_buffer_uptodate(&BTRFS_I(btree_inode)->io_tree, buf);
1834         if (!ret)
1835                 return ret;
1836
1837         ret = verify_parent_transid(&BTRFS_I(btree_inode)->io_tree, buf,
1838                                     parent_transid);
1839         return !ret;
1840 }
1841
1842 int btrfs_set_buffer_uptodate(struct extent_buffer *buf)
1843 {
1844         struct inode *btree_inode = buf->first_page->mapping->host;
1845         return set_extent_buffer_uptodate(&BTRFS_I(btree_inode)->io_tree,
1846                                           buf);
1847 }
1848
1849 void btrfs_mark_buffer_dirty(struct extent_buffer *buf)
1850 {
1851         struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
1852         u64 transid = btrfs_header_generation(buf);
1853         struct inode *btree_inode = root->fs_info->btree_inode;
1854
1855         WARN_ON(!btrfs_tree_locked(buf));
1856         if (transid != root->fs_info->generation) {
1857                 printk(KERN_CRIT "transid mismatch buffer %llu, found %Lu running %Lu\n",
1858                         (unsigned long long)buf->start,
1859                         transid, root->fs_info->generation);
1860                 WARN_ON(1);
1861         }
1862         set_extent_buffer_dirty(&BTRFS_I(btree_inode)->io_tree, buf);
1863 }
1864
1865 void btrfs_btree_balance_dirty(struct btrfs_root *root, unsigned long nr)
1866 {
1867         /*
1868          * looks as though older kernels can get into trouble with
1869          * this code, they end up stuck in balance_dirty_pages forever
1870          */
1871         struct extent_io_tree *tree;
1872         u64 num_dirty;
1873         u64 start = 0;
1874         unsigned long thresh = 96 * 1024 * 1024;
1875         tree = &BTRFS_I(root->fs_info->btree_inode)->io_tree;
1876
1877         if (current_is_pdflush() || current->flags & PF_MEMALLOC)
1878                 return;
1879
1880         num_dirty = count_range_bits(tree, &start, (u64)-1,
1881                                      thresh, EXTENT_DIRTY);
1882         if (num_dirty > thresh) {
1883                 balance_dirty_pages_ratelimited_nr(
1884                                    root->fs_info->btree_inode->i_mapping, 1);
1885         }
1886         return;
1887 }
1888
1889 int btrfs_read_buffer(struct extent_buffer *buf, u64 parent_transid)
1890 {
1891         struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
1892         int ret;
1893         ret = btree_read_extent_buffer_pages(root, buf, 0, parent_transid);
1894         if (ret == 0) {
1895                 buf->flags |= EXTENT_UPTODATE;
1896         }
1897         return ret;
1898 }
1899
1900 static struct extent_io_ops btree_extent_io_ops = {
1901         .writepage_io_hook = btree_writepage_io_hook,
1902         .readpage_end_io_hook = btree_readpage_end_io_hook,
1903         .submit_bio_hook = btree_submit_bio_hook,
1904         /* note we're sharing with inode.c for the merge bio hook */
1905         .merge_bio_hook = btrfs_merge_bio_hook,
1906 };