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 printk("read extent buffer pages failed with ret %d mirror no %d\n", ret, mirror_num);
 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                 printk("bad tree block start %llu %llu\n",
 352                        (unsigned long long)found_start,
 353                        (unsigned long long)eb->start);
 354                 ret = -EIO;
 355                 goto err;
 356         }
 357         if (eb->first_page != page) {
 358                 printk("bad first page %lu %lu\n", eb->first_page->index,
 359                        page->index);
 360                 WARN_ON(1);
 361                 ret = -EIO;
 362                 goto err;
 363         }
 364         if (memcmp_extent_buffer(eb, root->fs_info->fsid,
 365                                  (unsigned long)btrfs_header_fsid(eb),
 366                                  BTRFS_FSID_SIZE)) {
 367                 printk("bad fsid on block %Lu\n", eb->start);
 368                 ret = -EIO;
 369                 goto err;
 370         }
 371         found_level = btrfs_header_level(eb);
 372
 373         ret = csum_tree_block(root, eb, 1);
 374         if (ret)
 375                 ret = -EIO;
 376
 377         end = min_t(u64, eb->len, PAGE_CACHE_SIZE);
 378         end = eb->start + end - 1;
 379 err:
 380         free_extent_buffer(eb);
 381 out:
 382         return ret;
 383 }
 384
 385 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,23)
 386 static void end_workqueue_bio(struct bio *bio, int err)
 387 #else
 388 static int end_workqueue_bio(struct bio *bio,
 389                                    unsigned int bytes_done, int err)
 390 #endif
 391 {
 392         struct end_io_wq *end_io_wq = bio->bi_private;
 393         struct btrfs_fs_info *fs_info;
 394
 395 #if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
 396         if (bio->bi_size)
 397                 return 1;
 398 #endif
 399
 400         fs_info = end_io_wq->info;
 401         end_io_wq->error = err;
 402         end_io_wq->work.func = end_workqueue_fn;
 403         end_io_wq->work.flags = 0;
 404         if (bio->bi_rw & (1 << BIO_RW))
 405                 btrfs_queue_worker(&fs_info->endio_write_workers,
 406                                    &end_io_wq->work);
 407         else
 408                 btrfs_queue_worker(&fs_info->endio_workers, &end_io_wq->work);
 409
 410 #if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
 411         return 0;
 412 #endif
 413 }
 414
 415 int btrfs_bio_wq_end_io(struct btrfs_fs_info *info, struct bio *bio,
 416                         int metadata)
 417 {
 418         struct end_io_wq *end_io_wq;
 419         end_io_wq = kmalloc(sizeof(*end_io_wq), GFP_NOFS);
 420         if (!end_io_wq)
 421                 return -ENOMEM;
 422
 423         end_io_wq->private = bio->bi_private;
 424         end_io_wq->end_io = bio->bi_end_io;
 425         end_io_wq->info = info;
 426         end_io_wq->error = 0;
 427         end_io_wq->bio = bio;
 428         end_io_wq->metadata = metadata;
 429
 430         bio->bi_private = end_io_wq;
 431         bio->bi_end_io = end_workqueue_bio;
 432         return 0;
 433 }
 434
 435 unsigned long btrfs_async_submit_limit(struct btrfs_fs_info *info)
 436 {
 437         unsigned long limit = min_t(unsigned long,
 438                                     info->workers.max_workers,
 439                                     info->fs_devices->open_devices);
 440         return 256 * limit;
 441 }
 442
 443 int btrfs_congested_async(struct btrfs_fs_info *info, int iodone)
 444 {
 445         return atomic_read(&info->nr_async_bios) >
 446                 btrfs_async_submit_limit(info);
 447 }
 448
 449 static void run_one_async_submit(struct btrfs_work *work)
 450 {
 451         struct btrfs_fs_info *fs_info;
 452         struct async_submit_bio *async;
 453         int limit;
 454
 455         async = container_of(work, struct  async_submit_bio, work);
 456         fs_info = BTRFS_I(async->inode)->root->fs_info;
 457
 458         limit = btrfs_async_submit_limit(fs_info);
 459         limit = limit * 2 / 3;
 460
 461         atomic_dec(&fs_info->nr_async_submits);
 462
 463         if (atomic_read(&fs_info->nr_async_submits) < limit &&
 464             waitqueue_active(&fs_info->async_submit_wait))
 465                 wake_up(&fs_info->async_submit_wait);
 466
 467         async->submit_bio_hook(async->inode, async->rw, async->bio,
 468                                async->mirror_num);
 469         kfree(async);
 470 }
 471
 472 int btrfs_wq_submit_bio(struct btrfs_fs_info *fs_info, struct inode *inode,
 473                         int rw, struct bio *bio, int mirror_num,
 474                         extent_submit_bio_hook_t *submit_bio_hook)
 475 {
 476         struct async_submit_bio *async;
 477         int limit = btrfs_async_submit_limit(fs_info);
 478
 479         async = kmalloc(sizeof(*async), GFP_NOFS);
 480         if (!async)
 481                 return -ENOMEM;
 482
 483         async->inode = inode;
 484         async->rw = rw;
 485         async->bio = bio;
 486         async->mirror_num = mirror_num;
 487         async->submit_bio_hook = submit_bio_hook;
 488         async->work.func = run_one_async_submit;
 489         async->work.flags = 0;
 490         atomic_inc(&fs_info->nr_async_submits);
 491         btrfs_queue_worker(&fs_info->workers, &async->work);
 492
 493         if (atomic_read(&fs_info->nr_async_submits) > limit) {
 494                 wait_event_timeout(fs_info->async_submit_wait,
 495                            (atomic_read(&fs_info->nr_async_submits) < limit),
 496                            HZ/10);
 497
 498                 wait_event_timeout(fs_info->async_submit_wait,
 499                            (atomic_read(&fs_info->nr_async_bios) < limit),
 500                            HZ/10);
 501         }
 502         return 0;
 503 }
 504
 505 static int __btree_submit_bio_hook(struct inode *inode, int rw, struct bio *bio,
 506                                  int mirror_num)
 507 {
 508         struct btrfs_root *root = BTRFS_I(inode)->root;
 509         u64 offset;
 510         int ret;
 511
 512         offset = bio->bi_sector << 9;
 513
 514         /*
 515          * when we're called for a write, we're already in the async
 516          * submission context.  Just jump into btrfs_map_bio
 517          */
 518         if (rw & (1 << BIO_RW)) {
 519                 return btrfs_map_bio(BTRFS_I(inode)->root, rw, bio,
 520                                      mirror_num, 1);
 521         }
 522
 523         /*
 524          * called for a read, do the setup so that checksum validation
 525          * can happen in the async kernel threads
 526          */
 527         ret = btrfs_bio_wq_end_io(root->fs_info, bio, 1);
 528         BUG_ON(ret);
 529
 530         return btrfs_map_bio(BTRFS_I(inode)->root, rw, bio, mirror_num, 1);
 531 }
 532
 533 static int btree_submit_bio_hook(struct inode *inode, int rw, struct bio *bio,
 534                                  int mirror_num)
 535 {
 536         /*
 537          * kthread helpers are used to submit writes so that checksumming
 538          * can happen in parallel across all CPUs
 539          */
 540         if (!(rw & (1 << BIO_RW))) {
 541                 return __btree_submit_bio_hook(inode, rw, bio, mirror_num);
 542         }
 543         return btrfs_wq_submit_bio(BTRFS_I(inode)->root->fs_info,
 544                                    inode, rw, bio, mirror_num,
 545                                    __btree_submit_bio_hook);
 546 }
 547
 548 static int btree_writepage(struct page *page, struct writeback_control *wbc)
 549 {
 550         struct extent_io_tree *tree;
 551         tree = &BTRFS_I(page->mapping->host)->io_tree;
 552
 553         if (current->flags & PF_MEMALLOC) {
 554                 redirty_page_for_writepage(wbc, page);
 555                 unlock_page(page);
 556                 return 0;
 557         }
 558         return extent_write_full_page(tree, page, btree_get_extent, wbc);
 559 }
 560
 561 static int btree_writepages(struct address_space *mapping,
 562                             struct writeback_control *wbc)
 563 {
 564         struct extent_io_tree *tree;
 565         tree = &BTRFS_I(mapping->host)->io_tree;
 566         if (wbc->sync_mode == WB_SYNC_NONE) {
 567                 u64 num_dirty;
 568                 u64 start = 0;
 569                 unsigned long thresh = 8 * 1024 * 1024;
 570
 571                 if (wbc->for_kupdate)
 572                         return 0;
 573
 574                 num_dirty = count_range_bits(tree, &start, (u64)-1,
 575                                              thresh, EXTENT_DIRTY);
 576                 if (num_dirty < thresh) {
 577                         return 0;
 578                 }
 579         }
 580         return extent_writepages(tree, mapping, btree_get_extent, wbc);
 581 }
 582
 583 int btree_readpage(struct file *file, struct page *page)
 584 {
 585         struct extent_io_tree *tree;
 586         tree = &BTRFS_I(page->mapping->host)->io_tree;
 587         return extent_read_full_page(tree, page, btree_get_extent);
 588 }
 589
 590 static int btree_releasepage(struct page *page, gfp_t gfp_flags)
 591 {
 592         struct extent_io_tree *tree;
 593         struct extent_map_tree *map;
 594         int ret;
 595
 596         tree = &BTRFS_I(page->mapping->host)->io_tree;
 597         map = &BTRFS_I(page->mapping->host)->extent_tree;
 598
 599         ret = try_release_extent_state(map, tree, page, gfp_flags);
 600         if (!ret) {
 601                 return 0;
 602         }
 603
 604         ret = try_release_extent_buffer(tree, page);
 605         if (ret == 1) {
 606                 ClearPagePrivate(page);
 607                 set_page_private(page, 0);
 608                 page_cache_release(page);
 609         }
 610
 611         return ret;
 612 }
 613
 614 static void btree_invalidatepage(struct page *page, unsigned long offset)
 615 {
 616         struct extent_io_tree *tree;
 617         tree = &BTRFS_I(page->mapping->host)->io_tree;
 618         extent_invalidatepage(tree, page, offset);
 619         btree_releasepage(page, GFP_NOFS);
 620         if (PagePrivate(page)) {
 621                 printk("warning page private not zero on page %Lu\n",
 622                        page_offset(page));
 623                 ClearPagePrivate(page);
 624                 set_page_private(page, 0);
 625                 page_cache_release(page);
 626         }
 627 }
 628
 629 #if 0
 630 static int btree_writepage(struct page *page, struct writeback_control *wbc)
 631 {
 632         struct buffer_head *bh;
 633         struct btrfs_root *root = BTRFS_I(page->mapping->host)->root;
 634         struct buffer_head *head;
 635         if (!page_has_buffers(page)) {
 636                 create_empty_buffers(page, root->fs_info->sb->s_blocksize,
 637                                         (1 << BH_Dirty)|(1 << BH_Uptodate));
 638         }
 639         head = page_buffers(page);
 640         bh = head;
 641         do {
 642                 if (buffer_dirty(bh))
 643                         csum_tree_block(root, bh, 0);
 644                 bh = bh->b_this_page;
 645         } while (bh != head);
 646         return block_write_full_page(page, btree_get_block, wbc);
 647 }
 648 #endif
 649
 650 static struct address_space_operations btree_aops = {
 651         .readpage       = btree_readpage,
 652         .writepage      = btree_writepage,
 653         .writepages     = btree_writepages,
 654         .releasepage    = btree_releasepage,
 655         .invalidatepage = btree_invalidatepage,
 656         .sync_page      = block_sync_page,
 657 };
 658
 659 int readahead_tree_block(struct btrfs_root *root, u64 bytenr, u32 blocksize,
 660                          u64 parent_transid)
 661 {
 662         struct extent_buffer *buf = NULL;
 663         struct inode *btree_inode = root->fs_info->btree_inode;
 664         int ret = 0;
 665
 666         buf = btrfs_find_create_tree_block(root, bytenr, blocksize);
 667         if (!buf)
 668                 return 0;
 669         read_extent_buffer_pages(&BTRFS_I(btree_inode)->io_tree,
 670                                  buf, 0, 0, btree_get_extent, 0);
 671         free_extent_buffer(buf);
 672         return ret;
 673 }
 674
 675 struct extent_buffer *btrfs_find_tree_block(struct btrfs_root *root,
 676                                             u64 bytenr, u32 blocksize)
 677 {
 678         struct inode *btree_inode = root->fs_info->btree_inode;
 679         struct extent_buffer *eb;
 680         eb = find_extent_buffer(&BTRFS_I(btree_inode)->io_tree,
 681                                 bytenr, blocksize, GFP_NOFS);
 682         return eb;
 683 }
 684
 685 struct extent_buffer *btrfs_find_create_tree_block(struct btrfs_root *root,
 686                                                  u64 bytenr, u32 blocksize)
 687 {
 688         struct inode *btree_inode = root->fs_info->btree_inode;
 689         struct extent_buffer *eb;
 690
 691         eb = alloc_extent_buffer(&BTRFS_I(btree_inode)->io_tree,
 692                                  bytenr, blocksize, NULL, GFP_NOFS);
 693         return eb;
 694 }
 695
 696
 697 struct extent_buffer *read_tree_block(struct btrfs_root *root, u64 bytenr,
 698                                       u32 blocksize, u64 parent_transid)
 699 {
 700         struct extent_buffer *buf = NULL;
 701         struct inode *btree_inode = root->fs_info->btree_inode;
 702         struct extent_io_tree *io_tree;
 703         int ret;
 704
 705         io_tree = &BTRFS_I(btree_inode)->io_tree;
 706
 707         buf = btrfs_find_create_tree_block(root, bytenr, blocksize);
 708         if (!buf)
 709                 return NULL;
 710
 711         ret = btree_read_extent_buffer_pages(root, buf, 0, parent_transid);
 712
 713         if (ret == 0) {
 714                 buf->flags |= EXTENT_UPTODATE;
 715         } else {
 716                 WARN_ON(1);
 717         }
 718         return buf;
 719
 720 }
 721
 722 int clean_tree_block(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 723                      struct extent_buffer *buf)
 724 {
 725         struct inode *btree_inode = root->fs_info->btree_inode;
 726         if (btrfs_header_generation(buf) ==
 727             root->fs_info->running_transaction->transid) {
 728                 WARN_ON(!btrfs_tree_locked(buf));
 729                 clear_extent_buffer_dirty(&BTRFS_I(btree_inode)->io_tree,
 730                                           buf);
 731         }
 732         return 0;
 733 }
 734
 735 int wait_on_tree_block_writeback(struct btrfs_root *root,
 736                                  struct extent_buffer *buf)
 737 {
 738         struct inode *btree_inode = root->fs_info->btree_inode;
 739         wait_on_extent_buffer_writeback(&BTRFS_I(btree_inode)->io_tree,
 740                                         buf);
 741         return 0;
 742 }
 743
 744 static int __setup_root(u32 nodesize, u32 leafsize, u32 sectorsize,
 745                         u32 stripesize, struct btrfs_root *root,
 746                         struct btrfs_fs_info *fs_info,
 747                         u64 objectid)
 748 {
 749         root->node = NULL;
 750         root->inode = NULL;
 751         root->commit_root = NULL;
 752         root->ref_tree = NULL;
 753         root->sectorsize = sectorsize;
 754         root->nodesize = nodesize;
 755         root->leafsize = leafsize;
 756         root->stripesize = stripesize;
 757         root->ref_cows = 0;
 758         root->track_dirty = 0;
 759
 760         root->fs_info = fs_info;
 761         root->objectid = objectid;
 762         root->last_trans = 0;
 763         root->highest_inode = 0;
 764         root->last_inode_alloc = 0;
 765         root->name = NULL;
 766         root->in_sysfs = 0;
 767
 768         INIT_LIST_HEAD(&root->dirty_list);
 769         INIT_LIST_HEAD(&root->orphan_list);
 770         INIT_LIST_HEAD(&root->dead_list);
 771         spin_lock_init(&root->node_lock);
 772         spin_lock_init(&root->list_lock);
 773         mutex_init(&root->objectid_mutex);
 774
 775         btrfs_leaf_ref_tree_init(&root->ref_tree_struct);
 776         root->ref_tree = &root->ref_tree_struct;
 777
 778         memset(&root->root_key, 0, sizeof(root->root_key));
 779         memset(&root->root_item, 0, sizeof(root->root_item));
 780         memset(&root->defrag_progress, 0, sizeof(root->defrag_progress));
 781         memset(&root->root_kobj, 0, sizeof(root->root_kobj));
 782         root->defrag_trans_start = fs_info->generation;
 783         init_completion(&root->kobj_unregister);
 784         root->defrag_running = 0;
 785         root->defrag_level = 0;
 786         root->root_key.objectid = objectid;
 787         return 0;
 788 }
 789
 790 static int find_and_setup_root(struct btrfs_root *tree_root,
 791                                struct btrfs_fs_info *fs_info,
 792                                u64 objectid,
 793                                struct btrfs_root *root)
 794 {
 795         int ret;
 796         u32 blocksize;
 797
 798         __setup_root(tree_root->nodesize, tree_root->leafsize,
 799                      tree_root->sectorsize, tree_root->stripesize,
 800                      root, fs_info, objectid);
 801         ret = btrfs_find_last_root(tree_root, objectid,
 802                                    &root->root_item, &root->root_key);
 803         BUG_ON(ret);
 804
 805         blocksize = btrfs_level_size(root, btrfs_root_level(&root->root_item));
 806         root->node = read_tree_block(root, btrfs_root_bytenr(&root->root_item),
 807                                      blocksize, 0);
 808         BUG_ON(!root->node);
 809         return 0;
 810 }
 811
 812 struct btrfs_root *btrfs_read_fs_root_no_radix(struct btrfs_fs_info *fs_info,
 813                                                struct btrfs_key *location)
 814 {
 815         struct btrfs_root *root;
 816         struct btrfs_root *tree_root = fs_info->tree_root;
 817         struct btrfs_path *path;
 818         struct extent_buffer *l;
 819         u64 highest_inode;
 820         u32 blocksize;
 821         int ret = 0;
 822
 823         root = kzalloc(sizeof(*root), GFP_NOFS);
 824         if (!root)
 825                 return ERR_PTR(-ENOMEM);
 826         if (location->offset == (u64)-1) {
 827                 ret = find_and_setup_root(tree_root, fs_info,
 828                                           location->objectid, root);
 829                 if (ret) {
 830                         kfree(root);
 831                         return ERR_PTR(ret);
 832                 }
 833                 goto insert;
 834         }
 835
 836         __setup_root(tree_root->nodesize, tree_root->leafsize,
 837                      tree_root->sectorsize, tree_root->stripesize,
 838                      root, fs_info, location->objectid);
 839
 840         path = btrfs_alloc_path();
 841         BUG_ON(!path);
 842         ret = btrfs_search_slot(NULL, tree_root, location, path, 0, 0);
 843         if (ret != 0) {
 844                 if (ret > 0)
 845                         ret = -ENOENT;
 846                 goto out;
 847         }
 848         l = path->nodes[0];
 849         read_extent_buffer(l, &root->root_item,
 850                btrfs_item_ptr_offset(l, path->slots[0]),
 851                sizeof(root->root_item));
 852         memcpy(&root->root_key, location, sizeof(*location));
 853         ret = 0;
 854 out:
 855         btrfs_release_path(root, path);
 856         btrfs_free_path(path);
 857         if (ret) {
 858                 kfree(root);
 859                 return ERR_PTR(ret);
 860         }
 861         blocksize = btrfs_level_size(root, btrfs_root_level(&root->root_item));
 862         root->node = read_tree_block(root, btrfs_root_bytenr(&root->root_item),
 863                                      blocksize, 0);
 864         BUG_ON(!root->node);
 865 insert:
 866         root->ref_cows = 1;
 867         ret = btrfs_find_highest_inode(root, &highest_inode);
 868         if (ret == 0) {
 869                 root->highest_inode = highest_inode;
 870                 root->last_inode_alloc = highest_inode;
 871         }
 872         return root;
 873 }
 874
 875 struct btrfs_root *btrfs_lookup_fs_root(struct btrfs_fs_info *fs_info,
 876                                         u64 root_objectid)
 877 {
 878         struct btrfs_root *root;
 879
 880         if (root_objectid == BTRFS_ROOT_TREE_OBJECTID)
 881                 return fs_info->tree_root;
 882         if (root_objectid == BTRFS_EXTENT_TREE_OBJECTID)
 883                 return fs_info->extent_root;
 884
 885         root = radix_tree_lookup(&fs_info->fs_roots_radix,
 886                                  (unsigned long)root_objectid);
 887         return root;
 888 }
 889
 890 struct btrfs_root *btrfs_read_fs_root_no_name(struct btrfs_fs_info *fs_info,
 891                                               struct btrfs_key *location)
 892 {
 893         struct btrfs_root *root;
 894         int ret;
 895
 896         if (location->objectid == BTRFS_ROOT_TREE_OBJECTID)
 897                 return fs_info->tree_root;
 898         if (location->objectid == BTRFS_EXTENT_TREE_OBJECTID)
 899                 return fs_info->extent_root;
 900         if (location->objectid == BTRFS_CHUNK_TREE_OBJECTID)
 901                 return fs_info->chunk_root;
 902         if (location->objectid == BTRFS_DEV_TREE_OBJECTID)
 903                 return fs_info->dev_root;
 904
 905         root = radix_tree_lookup(&fs_info->fs_roots_radix,
 906                                  (unsigned long)location->objectid);
 907         if (root)
 908                 return root;
 909
 910         root = btrfs_read_fs_root_no_radix(fs_info, location);
 911         if (IS_ERR(root))
 912                 return root;
 913         ret = radix_tree_insert(&fs_info->fs_roots_radix,
 914                                 (unsigned long)root->root_key.objectid,
 915                                 root);
 916         if (ret) {
 917                 free_extent_buffer(root->node);
 918                 kfree(root);
 919                 return ERR_PTR(ret);
 920         }
 921         ret = btrfs_find_dead_roots(fs_info->tree_root,
 922                                     root->root_key.objectid, root);
 923         BUG_ON(ret);
 924
 925         return root;
 926 }
 927
 928 struct btrfs_root *btrfs_read_fs_root(struct btrfs_fs_info *fs_info,
 929                                       struct btrfs_key *location,
 930                                       const char *name, int namelen)
 931 {
 932         struct btrfs_root *root;
 933         int ret;
 934
 935         root = btrfs_read_fs_root_no_name(fs_info, location);
 936         if (!root)
 937                 return NULL;
 938
 939         if (root->in_sysfs)
 940                 return root;
 941
 942         ret = btrfs_set_root_name(root, name, namelen);
 943         if (ret) {
 944                 free_extent_buffer(root->node);
 945                 kfree(root);
 946                 return ERR_PTR(ret);
 947         }
 948
 949         ret = btrfs_sysfs_add_root(root);
 950         if (ret) {
 951                 free_extent_buffer(root->node);
 952                 kfree(root->name);
 953                 kfree(root);
 954                 return ERR_PTR(ret);
 955         }
 956         root->in_sysfs = 1;
 957         return root;
 958 }
 959 #if 0
 960 static int add_hasher(struct btrfs_fs_info *info, char *type) {
 961         struct btrfs_hasher *hasher;
 962
 963         hasher = kmalloc(sizeof(*hasher), GFP_NOFS);
 964         if (!hasher)
 965                 return -ENOMEM;
 966         hasher->hash_tfm = crypto_alloc_hash(type, 0, CRYPTO_ALG_ASYNC);
 967         if (!hasher->hash_tfm) {
 968                 kfree(hasher);
 969                 return -EINVAL;
 970         }
 971         spin_lock(&info->hash_lock);
 972         list_add(&hasher->list, &info->hashers);
 973         spin_unlock(&info->hash_lock);
 974         return 0;
 975 }
 976 #endif
 977
 978 static int btrfs_congested_fn(void *congested_data, int bdi_bits)
 979 {
 980         struct btrfs_fs_info *info = (struct btrfs_fs_info *)congested_data;
 981         int ret = 0;
 982         struct list_head *cur;
 983         struct btrfs_device *device;
 984         struct backing_dev_info *bdi;
 985
 986         if ((bdi_bits & (1 << BDI_write_congested)) &&
 987             btrfs_congested_async(info, 0))
 988                 return 1;
 989
 990         list_for_each(cur, &info->fs_devices->devices) {
 991                 device = list_entry(cur, struct btrfs_device, dev_list);
 992                 if (!device->bdev)
 993                         continue;
 994                 bdi = blk_get_backing_dev_info(device->bdev);
 995                 if (bdi && bdi_congested(bdi, bdi_bits)) {
 996                         ret = 1;
 997                         break;
 998                 }
 999         }
1000         return ret;
1001 }
1002
1003 /*
1004  * this unplugs every device on the box, and it is only used when page
1005  * is null
1006  */
1007 static void __unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
1008 {
1009         struct list_head *cur;
1010         struct btrfs_device *device;
1011         struct btrfs_fs_info *info;
1012
1013         info = (struct btrfs_fs_info *)bdi->unplug_io_data;
1014         list_for_each(cur, &info->fs_devices->devices) {
1015                 device = list_entry(cur, struct btrfs_device, dev_list);
1016                 bdi = blk_get_backing_dev_info(device->bdev);
1017                 if (bdi->unplug_io_fn) {
1018                         bdi->unplug_io_fn(bdi, page);
1019                 }
1020         }
1021 }
1022
1023 void btrfs_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
1024 {
1025         struct inode *inode;
1026         struct extent_map_tree *em_tree;
1027         struct extent_map *em;
1028         struct address_space *mapping;
1029         u64 offset;
1030
1031         /* the generic O_DIRECT read code does this */
1032         if (!page) {
1033                 __unplug_io_fn(bdi, page);
1034                 return;
1035         }
1036
1037         /*
1038          * page->mapping may change at any time.  Get a consistent copy
1039          * and use that for everything below
1040          */
1041         smp_mb();
1042         mapping = page->mapping;
1043         if (!mapping)
1044                 return;
1045
1046         inode = mapping->host;
1047         offset = page_offset(page);
1048
1049         em_tree = &BTRFS_I(inode)->extent_tree;
1050         spin_lock(&em_tree->lock);
1051         em = lookup_extent_mapping(em_tree, offset, PAGE_CACHE_SIZE);
1052         spin_unlock(&em_tree->lock);
1053         if (!em) {
1054                 __unplug_io_fn(bdi, page);
1055                 return;
1056         }
1057
1058         if (em->block_start >= EXTENT_MAP_LAST_BYTE) {
1059                 free_extent_map(em);
1060                 __unplug_io_fn(bdi, page);
1061                 return;
1062         }
1063         offset = offset - em->start;
1064         btrfs_unplug_page(&BTRFS_I(inode)->root->fs_info->mapping_tree,
1065                           em->block_start + offset, page);
1066         free_extent_map(em);
1067 }
1068
1069 static int setup_bdi(struct btrfs_fs_info *info, struct backing_dev_info *bdi)
1070 {
1071 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,23)
1072         bdi_init(bdi);
1073 #endif
1074         bdi->ra_pages   = default_backing_dev_info.ra_pages;
1075         bdi->state              = 0;
1076         bdi->capabilities       = default_backing_dev_info.capabilities;
1077         bdi->unplug_io_fn       = btrfs_unplug_io_fn;
1078         bdi->unplug_io_data     = info;
1079         bdi->congested_fn       = btrfs_congested_fn;
1080         bdi->congested_data     = info;
1081         return 0;
1082 }
1083
1084 static int bio_ready_for_csum(struct bio *bio)
1085 {
1086         u64 length = 0;
1087         u64 buf_len = 0;
1088         u64 start = 0;
1089         struct page *page;
1090         struct extent_io_tree *io_tree = NULL;
1091         struct btrfs_fs_info *info = NULL;
1092         struct bio_vec *bvec;
1093         int i;
1094         int ret;
1095
1096         bio_for_each_segment(bvec, bio, i) {
1097                 page = bvec->bv_page;
1098                 if (page->private == EXTENT_PAGE_PRIVATE) {
1099                         length += bvec->bv_len;
1100                         continue;
1101                 }
1102                 if (!page->private) {
1103                         length += bvec->bv_len;
1104                         continue;
1105                 }
1106                 length = bvec->bv_len;
1107                 buf_len = page->private >> 2;
1108                 start = page_offset(page) + bvec->bv_offset;
1109                 io_tree = &BTRFS_I(page->mapping->host)->io_tree;
1110                 info = BTRFS_I(page->mapping->host)->root->fs_info;
1111         }
1112         /* are we fully contained in this bio? */
1113         if (buf_len <= length)
1114                 return 1;
1115
1116         ret = extent_range_uptodate(io_tree, start + length,
1117                                     start + buf_len - 1);
1118         if (ret == 1)
1119                 return ret;
1120         return ret;
1121 }
1122
1123 /*
1124  * called by the kthread helper functions to finally call the bio end_io
1125  * functions.  This is where read checksum verification actually happens
1126  */
1127 static void end_workqueue_fn(struct btrfs_work *work)
1128 {
1129         struct bio *bio;
1130         struct end_io_wq *end_io_wq;
1131         struct btrfs_fs_info *fs_info;
1132         int error;
1133
1134         end_io_wq = container_of(work, struct end_io_wq, work);
1135         bio = end_io_wq->bio;
1136         fs_info = end_io_wq->info;
1137
1138         /* metadata bios are special because the whole tree block must
1139          * be checksummed at once.  This makes sure the entire block is in
1140          * ram and up to date before trying to verify things.  For
1141          * blocksize <= pagesize, it is basically a noop
1142          */
1143         if (end_io_wq->metadata && !bio_ready_for_csum(bio)) {
1144                 btrfs_queue_worker(&fs_info->endio_workers,
1145                                    &end_io_wq->work);
1146                 return;
1147         }
1148         error = end_io_wq->error;
1149         bio->bi_private = end_io_wq->private;
1150         bio->bi_end_io = end_io_wq->end_io;
1151         kfree(end_io_wq);
1152 #if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
1153         bio_endio(bio, bio->bi_size, error);
1154 #else
1155         bio_endio(bio, error);
1156 #endif
1157 }
1158
1159 static int cleaner_kthread(void *arg)
1160 {
1161         struct btrfs_root *root = arg;
1162
1163         do {
1164                 smp_mb();
1165                 if (root->fs_info->closing)
1166                         break;
1167
1168                 vfs_check_frozen(root->fs_info->sb, SB_FREEZE_WRITE);
1169                 mutex_lock(&root->fs_info->cleaner_mutex);
1170                 btrfs_clean_old_snapshots(root);
1171                 mutex_unlock(&root->fs_info->cleaner_mutex);
1172
1173                 if (freezing(current)) {
1174                         refrigerator();
1175                 } else {
1176                         smp_mb();
1177                         if (root->fs_info->closing)
1178                                 break;
1179                         set_current_state(TASK_INTERRUPTIBLE);
1180                         schedule();
1181                         __set_current_state(TASK_RUNNING);
1182                 }
1183         } while (!kthread_should_stop());
1184         return 0;
1185 }
1186
1187 static int transaction_kthread(void *arg)
1188 {
1189         struct btrfs_root *root = arg;
1190         struct btrfs_trans_handle *trans;
1191         struct btrfs_transaction *cur;
1192         unsigned long now;
1193         unsigned long delay;
1194         int ret;
1195
1196         do {
1197                 smp_mb();
1198                 if (root->fs_info->closing)
1199                         break;
1200
1201                 delay = HZ * 30;
1202                 vfs_check_frozen(root->fs_info->sb, SB_FREEZE_WRITE);
1203                 mutex_lock(&root->fs_info->transaction_kthread_mutex);
1204
1205                 if (root->fs_info->total_ref_cache_size > 20 * 1024 * 1024) {
1206                         printk("btrfs: total reference cache size %Lu\n",
1207                                 root->fs_info->total_ref_cache_size);
1208                 }
1209
1210                 mutex_lock(&root->fs_info->trans_mutex);
1211                 cur = root->fs_info->running_transaction;
1212                 if (!cur) {
1213                         mutex_unlock(&root->fs_info->trans_mutex);
1214                         goto sleep;
1215                 }
1216
1217                 now = get_seconds();
1218                 if (now < cur->start_time || now - cur->start_time < 30) {
1219                         mutex_unlock(&root->fs_info->trans_mutex);
1220                         delay = HZ * 5;
1221                         goto sleep;
1222                 }
1223                 mutex_unlock(&root->fs_info->trans_mutex);
1224                 trans = btrfs_start_transaction(root, 1);
1225                 ret = btrfs_commit_transaction(trans, root);
1226 sleep:
1227                 wake_up_process(root->fs_info->cleaner_kthread);
1228                 mutex_unlock(&root->fs_info->transaction_kthread_mutex);
1229
1230                 if (freezing(current)) {
1231                         refrigerator();
1232                 } else {
1233                         if (root->fs_info->closing)
1234                                 break;
1235                         set_current_state(TASK_INTERRUPTIBLE);
1236                         schedule_timeout(delay);
1237                         __set_current_state(TASK_RUNNING);
1238                 }
1239         } while (!kthread_should_stop());
1240         return 0;
1241 }
1242
1243 struct btrfs_root *open_ctree(struct super_block *sb,
1244                               struct btrfs_fs_devices *fs_devices,
1245                               char *options)
1246 {
1247         u32 sectorsize;
1248         u32 nodesize;
1249         u32 leafsize;
1250         u32 blocksize;
1251         u32 stripesize;
1252         struct buffer_head *bh;
1253         struct btrfs_root *extent_root = kmalloc(sizeof(struct btrfs_root),
1254                                                  GFP_NOFS);
1255         struct btrfs_root *tree_root = kmalloc(sizeof(struct btrfs_root),
1256                                                GFP_NOFS);
1257         struct btrfs_fs_info *fs_info = kzalloc(sizeof(*fs_info),
1258                                                 GFP_NOFS);
1259         struct btrfs_root *chunk_root = kmalloc(sizeof(struct btrfs_root),
1260                                                 GFP_NOFS);
1261         struct btrfs_root *dev_root = kmalloc(sizeof(struct btrfs_root),
1262                                               GFP_NOFS);
1263         int ret;
1264         int err = -EINVAL;
1265
1266         struct btrfs_super_block *disk_super;
1267
1268         if (!extent_root || !tree_root || !fs_info) {
1269                 err = -ENOMEM;
1270                 goto fail;
1271         }
1272         INIT_RADIX_TREE(&fs_info->fs_roots_radix, GFP_NOFS);
1273         INIT_LIST_HEAD(&fs_info->trans_list);
1274         INIT_LIST_HEAD(&fs_info->dead_roots);
1275         INIT_LIST_HEAD(&fs_info->hashers);
1276         INIT_LIST_HEAD(&fs_info->delalloc_inodes);
1277         spin_lock_init(&fs_info->hash_lock);
1278         spin_lock_init(&fs_info->delalloc_lock);
1279         spin_lock_init(&fs_info->new_trans_lock);
1280         spin_lock_init(&fs_info->ref_cache_lock);
1281
1282         init_completion(&fs_info->kobj_unregister);
1283         fs_info->tree_root = tree_root;
1284         fs_info->extent_root = extent_root;
1285         fs_info->chunk_root = chunk_root;
1286         fs_info->dev_root = dev_root;
1287         fs_info->fs_devices = fs_devices;
1288         INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);
1289         INIT_LIST_HEAD(&fs_info->space_info);
1290         btrfs_mapping_init(&fs_info->mapping_tree);
1291         atomic_set(&fs_info->nr_async_submits, 0);
1292         atomic_set(&fs_info->nr_async_bios, 0);
1293         atomic_set(&fs_info->throttles, 0);
1294         atomic_set(&fs_info->throttle_gen, 0);
1295         fs_info->sb = sb;
1296         fs_info->max_extent = (u64)-1;
1297         fs_info->max_inline = 8192 * 1024;
1298         setup_bdi(fs_info, &fs_info->bdi);
1299         fs_info->btree_inode = new_inode(sb);
1300         fs_info->btree_inode->i_ino = 1;
1301         fs_info->btree_inode->i_nlink = 1;
1302         fs_info->thread_pool_size = min(num_online_cpus() + 2, 8);
1303
1304         INIT_LIST_HEAD(&fs_info->ordered_extents);
1305         spin_lock_init(&fs_info->ordered_extent_lock);
1306
1307         sb->s_blocksize = 4096;
1308         sb->s_blocksize_bits = blksize_bits(4096);
1309
1310         /*
1311          * we set the i_size on the btree inode to the max possible int.
1312          * the real end of the address space is determined by all of
1313          * the devices in the system
1314          */
1315         fs_info->btree_inode->i_size = OFFSET_MAX;
1316         fs_info->btree_inode->i_mapping->a_ops = &btree_aops;
1317         fs_info->btree_inode->i_mapping->backing_dev_info = &fs_info->bdi;
1318
1319         extent_io_tree_init(&BTRFS_I(fs_info->btree_inode)->io_tree,
1320                              fs_info->btree_inode->i_mapping,
1321                              GFP_NOFS);
1322         extent_map_tree_init(&BTRFS_I(fs_info->btree_inode)->extent_tree,
1323                              GFP_NOFS);
1324
1325         BTRFS_I(fs_info->btree_inode)->io_tree.ops = &btree_extent_io_ops;
1326
1327         extent_io_tree_init(&fs_info->free_space_cache,
1328                              fs_info->btree_inode->i_mapping, GFP_NOFS);
1329         extent_io_tree_init(&fs_info->block_group_cache,
1330                              fs_info->btree_inode->i_mapping, GFP_NOFS);
1331         extent_io_tree_init(&fs_info->pinned_extents,
1332                              fs_info->btree_inode->i_mapping, GFP_NOFS);
1333         extent_io_tree_init(&fs_info->pending_del,
1334                              fs_info->btree_inode->i_mapping, GFP_NOFS);
1335         extent_io_tree_init(&fs_info->extent_ins,
1336                              fs_info->btree_inode->i_mapping, GFP_NOFS);
1337         fs_info->do_barriers = 1;
1338
1339         BTRFS_I(fs_info->btree_inode)->root = tree_root;
1340         memset(&BTRFS_I(fs_info->btree_inode)->location, 0,
1341                sizeof(struct btrfs_key));
1342         insert_inode_hash(fs_info->btree_inode);
1343         mapping_set_gfp_mask(fs_info->btree_inode->i_mapping, GFP_NOFS);
1344
1345         mutex_init(&fs_info->trans_mutex);
1346         mutex_init(&fs_info->drop_mutex);
1347         mutex_init(&fs_info->alloc_mutex);
1348         mutex_init(&fs_info->chunk_mutex);
1349         mutex_init(&fs_info->transaction_kthread_mutex);
1350         mutex_init(&fs_info->cleaner_mutex);
1351         mutex_init(&fs_info->volume_mutex);
1352         init_waitqueue_head(&fs_info->transaction_throttle);
1353         init_waitqueue_head(&fs_info->transaction_wait);
1354         init_waitqueue_head(&fs_info->async_submit_wait);
1355
1356 #if 0
1357         ret = add_hasher(fs_info, "crc32c");
1358         if (ret) {
1359                 printk("btrfs: failed hash setup, modprobe cryptomgr?\n");
1360                 err = -ENOMEM;
1361                 goto fail_iput;
1362         }
1363 #endif
1364         __setup_root(4096, 4096, 4096, 4096, tree_root,
1365                      fs_info, BTRFS_ROOT_TREE_OBJECTID);
1366
1367
1368         bh = __bread(fs_devices->latest_bdev,
1369                      BTRFS_SUPER_INFO_OFFSET / 4096, 4096);
1370         if (!bh)
1371                 goto fail_iput;
1372
1373         memcpy(&fs_info->super_copy, bh->b_data, sizeof(fs_info->super_copy));
1374         brelse(bh);
1375
1376         memcpy(fs_info->fsid, fs_info->super_copy.fsid, BTRFS_FSID_SIZE);
1377
1378         disk_super = &fs_info->super_copy;
1379         if (!btrfs_super_root(disk_super))
1380                 goto fail_sb_buffer;
1381
1382         err = btrfs_parse_options(tree_root, options);
1383         if (err)
1384                 goto fail_sb_buffer;
1385
1386         /*
1387          * we need to start all the end_io workers up front because the
1388          * queue work function gets called at interrupt time, and so it
1389          * cannot dynamically grow.
1390          */
1391         btrfs_init_workers(&fs_info->workers, "worker",
1392                            fs_info->thread_pool_size);
1393         btrfs_init_workers(&fs_info->submit_workers, "submit",
1394                            min_t(u64, fs_devices->num_devices,
1395                            fs_info->thread_pool_size));
1396
1397         /* a higher idle thresh on the submit workers makes it much more
1398          * likely that bios will be send down in a sane order to the
1399          * devices
1400          */
1401         fs_info->submit_workers.idle_thresh = 64;
1402
1403         /* fs_info->workers is responsible for checksumming file data
1404          * blocks and metadata.  Using a larger idle thresh allows each
1405          * worker thread to operate on things in roughly the order they
1406          * were sent by the writeback daemons, improving overall locality
1407          * of the IO going down the pipe.
1408          */
1409         fs_info->workers.idle_thresh = 128;
1410
1411         btrfs_init_workers(&fs_info->fixup_workers, "fixup", 1);
1412         btrfs_init_workers(&fs_info->endio_workers, "endio",
1413                            fs_info->thread_pool_size);
1414         btrfs_init_workers(&fs_info->endio_write_workers, "endio-write",
1415                            fs_info->thread_pool_size);
1416
1417         /*
1418          * endios are largely parallel and should have a very
1419          * low idle thresh
1420          */
1421         fs_info->endio_workers.idle_thresh = 4;
1422         fs_info->endio_write_workers.idle_thresh = 4;
1423
1424         btrfs_start_workers(&fs_info->workers, 1);
1425         btrfs_start_workers(&fs_info->submit_workers, 1);
1426         btrfs_start_workers(&fs_info->fixup_workers, 1);
1427         btrfs_start_workers(&fs_info->endio_workers, fs_info->thread_pool_size);
1428         btrfs_start_workers(&fs_info->endio_write_workers,
1429                             fs_info->thread_pool_size);
1430
1431         err = -EINVAL;
1432         if (btrfs_super_num_devices(disk_super) > fs_devices->open_devices) {
1433                 printk("Btrfs: wanted %llu devices, but found %llu\n",
1434                        (unsigned long long)btrfs_super_num_devices(disk_super),
1435                        (unsigned long long)fs_devices->open_devices);
1436                 if (btrfs_test_opt(tree_root, DEGRADED))
1437                         printk("continuing in degraded mode\n");
1438                 else {
1439                         goto fail_sb_buffer;
1440                 }
1441         }
1442
1443         fs_info->bdi.ra_pages *= btrfs_super_num_devices(disk_super);
1444
1445         nodesize = btrfs_super_nodesize(disk_super);
1446         leafsize = btrfs_super_leafsize(disk_super);
1447         sectorsize = btrfs_super_sectorsize(disk_super);
1448         stripesize = btrfs_super_stripesize(disk_super);
1449         tree_root->nodesize = nodesize;
1450         tree_root->leafsize = leafsize;
1451         tree_root->sectorsize = sectorsize;
1452         tree_root->stripesize = stripesize;
1453
1454         sb->s_blocksize = sectorsize;
1455         sb->s_blocksize_bits = blksize_bits(sectorsize);
1456
1457         if (strncmp((char *)(&disk_super->magic), BTRFS_MAGIC,
1458                     sizeof(disk_super->magic))) {
1459                 printk("btrfs: valid FS not found on %s\n", sb->s_id);
1460                 goto fail_sb_buffer;
1461         }
1462
1463         mutex_lock(&fs_info->chunk_mutex);
1464         ret = btrfs_read_sys_array(tree_root);
1465         mutex_unlock(&fs_info->chunk_mutex);
1466         if (ret) {
1467                 printk("btrfs: failed to read the system array on %s\n",
1468                        sb->s_id);
1469                 goto fail_sys_array;
1470         }
1471
1472         blocksize = btrfs_level_size(tree_root,
1473                                      btrfs_super_chunk_root_level(disk_super));
1474
1475         __setup_root(nodesize, leafsize, sectorsize, stripesize,
1476                      chunk_root, fs_info, BTRFS_CHUNK_TREE_OBJECTID);
1477
1478         chunk_root->node = read_tree_block(chunk_root,
1479                                            btrfs_super_chunk_root(disk_super),
1480                                            blocksize, 0);
1481         BUG_ON(!chunk_root->node);
1482
1483         read_extent_buffer(chunk_root->node, fs_info->chunk_tree_uuid,
1484                  (unsigned long)btrfs_header_chunk_tree_uuid(chunk_root->node),
1485                  BTRFS_UUID_SIZE);
1486
1487         mutex_lock(&fs_info->chunk_mutex);
1488         ret = btrfs_read_chunk_tree(chunk_root);
1489         mutex_unlock(&fs_info->chunk_mutex);
1490         BUG_ON(ret);
1491
1492         btrfs_close_extra_devices(fs_devices);
1493
1494         blocksize = btrfs_level_size(tree_root,
1495                                      btrfs_super_root_level(disk_super));
1496
1497
1498         tree_root->node = read_tree_block(tree_root,
1499                                           btrfs_super_root(disk_super),
1500                                           blocksize, 0);
1501         if (!tree_root->node)
1502                 goto fail_sb_buffer;
1503
1504
1505         ret = find_and_setup_root(tree_root, fs_info,
1506                                   BTRFS_EXTENT_TREE_OBJECTID, extent_root);
1507         if (ret)
1508                 goto fail_tree_root;
1509         extent_root->track_dirty = 1;
1510
1511         ret = find_and_setup_root(tree_root, fs_info,
1512                                   BTRFS_DEV_TREE_OBJECTID, dev_root);
1513         dev_root->track_dirty = 1;
1514
1515         if (ret)
1516                 goto fail_extent_root;
1517
1518         btrfs_read_block_groups(extent_root);
1519
1520         fs_info->generation = btrfs_super_generation(disk_super) + 1;
1521         fs_info->data_alloc_profile = (u64)-1;
1522         fs_info->metadata_alloc_profile = (u64)-1;
1523         fs_info->system_alloc_profile = fs_info->metadata_alloc_profile;
1524         fs_info->cleaner_kthread = kthread_run(cleaner_kthread, tree_root,
1525                                                "btrfs-cleaner");
1526         if (!fs_info->cleaner_kthread)
1527                 goto fail_extent_root;
1528
1529         fs_info->transaction_kthread = kthread_run(transaction_kthread,
1530                                                    tree_root,
1531                                                    "btrfs-transaction");
1532         if (!fs_info->transaction_kthread)
1533                 goto fail_cleaner;
1534
1535
1536         return tree_root;
1537
1538 fail_cleaner:
1539         kthread_stop(fs_info->cleaner_kthread);
1540 fail_extent_root:
1541         free_extent_buffer(extent_root->node);
1542 fail_tree_root:
1543         free_extent_buffer(tree_root->node);
1544 fail_sys_array:
1545 fail_sb_buffer:
1546         btrfs_stop_workers(&fs_info->fixup_workers);
1547         btrfs_stop_workers(&fs_info->workers);
1548         btrfs_stop_workers(&fs_info->endio_workers);
1549         btrfs_stop_workers(&fs_info->endio_write_workers);
1550         btrfs_stop_workers(&fs_info->submit_workers);
1551 fail_iput:
1552         iput(fs_info->btree_inode);
1553 fail:
1554         btrfs_close_devices(fs_info->fs_devices);
1555         btrfs_mapping_tree_free(&fs_info->mapping_tree);
1556
1557         kfree(extent_root);
1558         kfree(tree_root);
1559 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,23)
1560         bdi_destroy(&fs_info->bdi);
1561 #endif
1562         kfree(fs_info);
1563         return ERR_PTR(err);
1564 }
1565
1566 static void btrfs_end_buffer_write_sync(struct buffer_head *bh, int uptodate)
1567 {
1568         char b[BDEVNAME_SIZE];
1569
1570         if (uptodate) {
1571                 set_buffer_uptodate(bh);
1572         } else {
1573                 if (!buffer_eopnotsupp(bh) && printk_ratelimit()) {
1574                         printk(KERN_WARNING "lost page write due to "
1575                                         "I/O error on %s\n",
1576                                        bdevname(bh->b_bdev, b));
1577                 }
1578                 /* note, we dont' set_buffer_write_io_error because we have
1579                  * our own ways of dealing with the IO errors
1580                  */
1581                 clear_buffer_uptodate(bh);
1582         }
1583         unlock_buffer(bh);
1584         put_bh(bh);
1585 }
1586
1587 int write_all_supers(struct btrfs_root *root)
1588 {
1589         struct list_head *cur;
1590         struct list_head *head = &root->fs_info->fs_devices->devices;
1591         struct btrfs_device *dev;
1592         struct btrfs_super_block *sb;
1593         struct btrfs_dev_item *dev_item;
1594         struct buffer_head *bh;
1595         int ret;
1596         int do_barriers;
1597         int max_errors;
1598         int total_errors = 0;
1599         u32 crc;
1600         u64 flags;
1601
1602         max_errors = btrfs_super_num_devices(&root->fs_info->super_copy) - 1;
1603         do_barriers = !btrfs_test_opt(root, NOBARRIER);
1604
1605         sb = &root->fs_info->super_for_commit;
1606         dev_item = &sb->dev_item;
1607         list_for_each(cur, head) {
1608                 dev = list_entry(cur, struct btrfs_device, dev_list);
1609                 if (!dev->bdev) {
1610                         total_errors++;
1611                         continue;
1612                 }
1613                 if (!dev->in_fs_metadata)
1614                         continue;
1615
1616                 btrfs_set_stack_device_type(dev_item, dev->type);
1617                 btrfs_set_stack_device_id(dev_item, dev->devid);
1618                 btrfs_set_stack_device_total_bytes(dev_item, dev->total_bytes);
1619                 btrfs_set_stack_device_bytes_used(dev_item, dev->bytes_used);
1620                 btrfs_set_stack_device_io_align(dev_item, dev->io_align);
1621                 btrfs_set_stack_device_io_width(dev_item, dev->io_width);
1622                 btrfs_set_stack_device_sector_size(dev_item, dev->sector_size);
1623                 memcpy(dev_item->uuid, dev->uuid, BTRFS_UUID_SIZE);
1624                 flags = btrfs_super_flags(sb);
1625                 btrfs_set_super_flags(sb, flags | BTRFS_HEADER_FLAG_WRITTEN);
1626
1627
1628                 crc = ~(u32)0;
1629                 crc = btrfs_csum_data(root, (char *)sb + BTRFS_CSUM_SIZE, crc,
1630                                       BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE);
1631                 btrfs_csum_final(crc, sb->csum);
1632
1633                 bh = __getblk(dev->bdev, BTRFS_SUPER_INFO_OFFSET / 4096,
1634                               BTRFS_SUPER_INFO_SIZE);
1635
1636                 memcpy(bh->b_data, sb, BTRFS_SUPER_INFO_SIZE);
1637                 dev->pending_io = bh;
1638
1639                 get_bh(bh);
1640                 set_buffer_uptodate(bh);
1641                 lock_buffer(bh);
1642                 bh->b_end_io = btrfs_end_buffer_write_sync;
1643
1644                 if (do_barriers && dev->barriers) {
1645                         ret = submit_bh(WRITE_BARRIER, bh);
1646                         if (ret == -EOPNOTSUPP) {
1647                                 printk("btrfs: disabling barriers on dev %s\n",
1648                                        dev->name);
1649                                 set_buffer_uptodate(bh);
1650                                 dev->barriers = 0;
1651                                 get_bh(bh);
1652                                 lock_buffer(bh);
1653                                 ret = submit_bh(WRITE, bh);
1654                         }
1655                 } else {
1656                         ret = submit_bh(WRITE, bh);
1657                 }
1658                 if (ret)
1659                         total_errors++;
1660         }
1661         if (total_errors > max_errors) {
1662                 printk("btrfs: %d errors while writing supers\n", total_errors);
1663                 BUG();
1664         }
1665         total_errors = 0;
1666
1667         list_for_each(cur, head) {
1668                 dev = list_entry(cur, struct btrfs_device, dev_list);
1669                 if (!dev->bdev)
1670                         continue;
1671                 if (!dev->in_fs_metadata)
1672                         continue;
1673
1674                 BUG_ON(!dev->pending_io);
1675                 bh = dev->pending_io;
1676                 wait_on_buffer(bh);
1677                 if (!buffer_uptodate(dev->pending_io)) {
1678                         if (do_barriers && dev->barriers) {
1679                                 printk("btrfs: disabling barriers on dev %s\n",
1680                                        dev->name);
1681                                 set_buffer_uptodate(bh);
1682                                 get_bh(bh);
1683                                 lock_buffer(bh);
1684                                 dev->barriers = 0;
1685                                 ret = submit_bh(WRITE, bh);
1686                                 BUG_ON(ret);
1687                                 wait_on_buffer(bh);
1688                                 if (!buffer_uptodate(bh))
1689                                         total_errors++;
1690                         } else {
1691                                 total_errors++;
1692                         }
1693
1694                 }
1695                 dev->pending_io = NULL;
1696                 brelse(bh);
1697         }
1698         if (total_errors > max_errors) {
1699                 printk("btrfs: %d errors while writing supers\n", total_errors);
1700                 BUG();
1701         }
1702         return 0;
1703 }
1704
1705 int write_ctree_super(struct btrfs_trans_handle *trans, struct btrfs_root
1706                       *root)
1707 {
1708         int ret;
1709
1710         ret = write_all_supers(root);
1711         return ret;
1712 }
1713
1714 int btrfs_free_fs_root(struct btrfs_fs_info *fs_info, struct btrfs_root *root)
1715 {
1716         radix_tree_delete(&fs_info->fs_roots_radix,
1717                           (unsigned long)root->root_key.objectid);
1718         if (root->in_sysfs)
1719                 btrfs_sysfs_del_root(root);
1720         if (root->inode)
1721                 iput(root->inode);
1722         if (root->node)
1723                 free_extent_buffer(root->node);
1724         if (root->commit_root)
1725                 free_extent_buffer(root->commit_root);
1726         if (root->name)
1727                 kfree(root->name);
1728         kfree(root);
1729         return 0;
1730 }
1731
1732 static int del_fs_roots(struct btrfs_fs_info *fs_info)
1733 {
1734         int ret;
1735         struct btrfs_root *gang[8];
1736         int i;
1737
1738         while(1) {
1739                 ret = radix_tree_gang_lookup(&fs_info->fs_roots_radix,
1740                                              (void **)gang, 0,
1741                                              ARRAY_SIZE(gang));
1742                 if (!ret)
1743                         break;
1744                 for (i = 0; i < ret; i++)
1745                         btrfs_free_fs_root(fs_info, gang[i]);
1746         }
1747         return 0;
1748 }
1749
1750 int close_ctree(struct btrfs_root *root)
1751 {
1752         int ret;
1753         struct btrfs_trans_handle *trans;
1754         struct btrfs_fs_info *fs_info = root->fs_info;
1755
1756         fs_info->closing = 1;
1757         smp_mb();
1758
1759         kthread_stop(root->fs_info->transaction_kthread);
1760         kthread_stop(root->fs_info->cleaner_kthread);
1761
1762         btrfs_clean_old_snapshots(root);
1763         trans = btrfs_start_transaction(root, 1);
1764         ret = btrfs_commit_transaction(trans, root);
1765         /* run commit again to  drop the original snapshot */
1766         trans = btrfs_start_transaction(root, 1);
1767         btrfs_commit_transaction(trans, root);
1768         ret = btrfs_write_and_wait_transaction(NULL, root);
1769         BUG_ON(ret);
1770
1771         write_ctree_super(NULL, root);
1772
1773         if (fs_info->delalloc_bytes) {
1774                 printk("btrfs: at unmount delalloc count %Lu\n",
1775                        fs_info->delalloc_bytes);
1776         }
1777         if (fs_info->total_ref_cache_size) {
1778                 printk("btrfs: at umount reference cache size %Lu\n",
1779                         fs_info->total_ref_cache_size);
1780         }
1781
1782         if (fs_info->extent_root->node)
1783                 free_extent_buffer(fs_info->extent_root->node);
1784
1785         if (fs_info->tree_root->node)
1786                 free_extent_buffer(fs_info->tree_root->node);
1787
1788         if (root->fs_info->chunk_root->node);
1789                 free_extent_buffer(root->fs_info->chunk_root->node);
1790
1791         if (root->fs_info->dev_root->node);
1792                 free_extent_buffer(root->fs_info->dev_root->node);
1793
1794         btrfs_free_block_groups(root->fs_info);
1795         fs_info->closing = 2;
1796         del_fs_roots(fs_info);
1797
1798         filemap_write_and_wait(fs_info->btree_inode->i_mapping);
1799
1800         truncate_inode_pages(fs_info->btree_inode->i_mapping, 0);
1801
1802         btrfs_stop_workers(&fs_info->fixup_workers);
1803         btrfs_stop_workers(&fs_info->workers);
1804         btrfs_stop_workers(&fs_info->endio_workers);
1805         btrfs_stop_workers(&fs_info->endio_write_workers);
1806         btrfs_stop_workers(&fs_info->submit_workers);
1807
1808         iput(fs_info->btree_inode);
1809 #if 0
1810         while(!list_empty(&fs_info->hashers)) {
1811                 struct btrfs_hasher *hasher;
1812                 hasher = list_entry(fs_info->hashers.next, struct btrfs_hasher,
1813                                     hashers);
1814                 list_del(&hasher->hashers);
1815                 crypto_free_hash(&fs_info->hash_tfm);
1816                 kfree(hasher);
1817         }
1818 #endif
1819         btrfs_close_devices(fs_info->fs_devices);
1820         btrfs_mapping_tree_free(&fs_info->mapping_tree);
1821
1822 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,23)
1823         bdi_destroy(&fs_info->bdi);
1824 #endif
1825
1826         kfree(fs_info->extent_root);
1827         kfree(fs_info->tree_root);
1828         kfree(fs_info->chunk_root);
1829         kfree(fs_info->dev_root);
1830         return 0;
1831 }
1832
1833 int btrfs_buffer_uptodate(struct extent_buffer *buf, u64 parent_transid)
1834 {
1835         int ret;
1836         struct inode *btree_inode = buf->first_page->mapping->host;
1837
1838         ret = extent_buffer_uptodate(&BTRFS_I(btree_inode)->io_tree, buf);
1839         if (!ret)
1840                 return ret;
1841
1842         ret = verify_parent_transid(&BTRFS_I(btree_inode)->io_tree, buf,
1843                                     parent_transid);
1844         return !ret;
1845 }
1846
1847 int btrfs_set_buffer_uptodate(struct extent_buffer *buf)
1848 {
1849         struct inode *btree_inode = buf->first_page->mapping->host;
1850         return set_extent_buffer_uptodate(&BTRFS_I(btree_inode)->io_tree,
1851                                           buf);
1852 }
1853
1854 void btrfs_mark_buffer_dirty(struct extent_buffer *buf)
1855 {
1856         struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
1857         u64 transid = btrfs_header_generation(buf);
1858         struct inode *btree_inode = root->fs_info->btree_inode;
1859
1860         WARN_ON(!btrfs_tree_locked(buf));
1861         if (transid != root->fs_info->generation) {
1862                 printk(KERN_CRIT "transid mismatch buffer %llu, found %Lu running %Lu\n",
1863                         (unsigned long long)buf->start,
1864                         transid, root->fs_info->generation);
1865                 WARN_ON(1);
1866         }
1867         set_extent_buffer_dirty(&BTRFS_I(btree_inode)->io_tree, buf);
1868 }
1869
1870 void btrfs_btree_balance_dirty(struct btrfs_root *root, unsigned long nr)
1871 {
1872         /*
1873          * looks as though older kernels can get into trouble with
1874          * this code, they end up stuck in balance_dirty_pages forever
1875          */
1876         struct extent_io_tree *tree;
1877         u64 num_dirty;
1878         u64 start = 0;
1879         unsigned long thresh = 96 * 1024 * 1024;
1880         tree = &BTRFS_I(root->fs_info->btree_inode)->io_tree;
1881
1882         if (current_is_pdflush() || current->flags & PF_MEMALLOC)
1883                 return;
1884
1885         num_dirty = count_range_bits(tree, &start, (u64)-1,
1886                                      thresh, EXTENT_DIRTY);
1887         if (num_dirty > thresh) {
1888                 balance_dirty_pages_ratelimited_nr(
1889                                    root->fs_info->btree_inode->i_mapping, 1);
1890         }
1891         return;
1892 }
1893
1894 int btrfs_read_buffer(struct extent_buffer *buf, u64 parent_transid)
1895 {
1896         struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
1897         int ret;
1898         ret = btree_read_extent_buffer_pages(root, buf, 0, parent_transid);
1899         if (ret == 0) {
1900                 buf->flags |= EXTENT_UPTODATE;
1901         }
1902         return ret;
1903 }
1904
1905 static struct extent_io_ops btree_extent_io_ops = {
1906         .writepage_io_hook = btree_writepage_io_hook,
1907         .readpage_end_io_hook = btree_readpage_end_io_hook,
1908         .submit_bio_hook = btree_submit_bio_hook,
1909         /* note we're sharing with inode.c for the merge bio hook */
1910         .merge_bio_hook = btrfs_merge_bio_hook,
1911 };