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/fs.h>
  20 #include <linux/blkdev.h>
  21 #include <linux/scatterlist.h>
  22 #include <linux/swap.h>
  23 #include <linux/radix-tree.h>
  24 #include <linux/writeback.h>
  25 #include <linux/buffer_head.h>
  26 #include <linux/workqueue.h>
  27 #include <linux/kthread.h>
  28 #include <linux/freezer.h>
  29 #include <linux/crc32c.h>
  30 #include <linux/slab.h>
  31 #include <linux/migrate.h>
  32 #include <linux/ratelimit.h>
  33 #include <asm/unaligned.h>
  34 #include "compat.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 "tree-log.h"
  44 #include "free-space-cache.h"
  45 #include "inode-map.h"
  46
  47 static struct extent_io_ops btree_extent_io_ops;
  48 static void end_workqueue_fn(struct btrfs_work *work);
  49 static void free_fs_root(struct btrfs_root *root);
  50 static void btrfs_check_super_valid(struct btrfs_fs_info *fs_info,
  51                                     int read_only);
  52 static int btrfs_destroy_ordered_operations(struct btrfs_root *root);
  53 static int btrfs_destroy_ordered_extents(struct btrfs_root *root);
  54 static int btrfs_destroy_delayed_refs(struct btrfs_transaction *trans,
  55                                       struct btrfs_root *root);
  56 static int btrfs_destroy_pending_snapshots(struct btrfs_transaction *t);
  57 static int btrfs_destroy_delalloc_inodes(struct btrfs_root *root);
  58 static int btrfs_destroy_marked_extents(struct btrfs_root *root,
  59                                         struct extent_io_tree *dirty_pages,
  60                                         int mark);
  61 static int btrfs_destroy_pinned_extent(struct btrfs_root *root,
  62                                        struct extent_io_tree *pinned_extents);
  63 static int btrfs_cleanup_transaction(struct btrfs_root *root);
  64
  65 /*
  66  * end_io_wq structs are used to do processing in task context when an IO is
  67  * complete.  This is used during reads to verify checksums, and it is used
  68  * by writes to insert metadata for new file extents after IO is complete.
  69  */
  70 struct end_io_wq {
  71         struct bio *bio;
  72         bio_end_io_t *end_io;
  73         void *private;
  74         struct btrfs_fs_info *info;
  75         int error;
  76         int metadata;
  77         struct list_head list;
  78         struct btrfs_work work;
  79 };
  80
  81 /*
  82  * async submit bios are used to offload expensive checksumming
  83  * onto the worker threads.  They checksum file and metadata bios
  84  * just before they are sent down the IO stack.
  85  */
  86 struct async_submit_bio {
  87         struct inode *inode;
  88         struct bio *bio;
  89         struct list_head list;
  90         extent_submit_bio_hook_t *submit_bio_start;
  91         extent_submit_bio_hook_t *submit_bio_done;
  92         int rw;
  93         int mirror_num;
  94         unsigned long bio_flags;
  95         /*
  96          * bio_offset is optional, can be used if the pages in the bio
  97          * can't tell us where in the file the bio should go
  98          */
  99         u64 bio_offset;
 100         struct btrfs_work work;
 101 };
 102
 103 /* These are used to set the lockdep class on the extent buffer locks.
 104  * The class is set by the readpage_end_io_hook after the buffer has
 105  * passed csum validation but before the pages are unlocked.
 106  *
 107  * The lockdep class is also set by btrfs_init_new_buffer on freshly
 108  * allocated blocks.
 109  *
 110  * The class is based on the level in the tree block, which allows lockdep
 111  * to know that lower nodes nest inside the locks of higher nodes.
 112  *
 113  * We also add a check to make sure the highest level of the tree is
 114  * the same as our lockdep setup here.  If BTRFS_MAX_LEVEL changes, this
 115  * code needs update as well.
 116  */
 117 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 118 # if BTRFS_MAX_LEVEL != 8
 119 #  error
 120 # endif
 121 static struct lock_class_key btrfs_eb_class[BTRFS_MAX_LEVEL + 1];
 122 static const char *btrfs_eb_name[BTRFS_MAX_LEVEL + 1] = {
 123         /* leaf */
 124         "btrfs-extent-00",
 125         "btrfs-extent-01",
 126         "btrfs-extent-02",
 127         "btrfs-extent-03",
 128         "btrfs-extent-04",
 129         "btrfs-extent-05",
 130         "btrfs-extent-06",
 131         "btrfs-extent-07",
 132         /* highest possible level */
 133         "btrfs-extent-08",
 134 };
 135 #endif
 136
 137 /*
 138  * extents on the btree inode are pretty simple, there's one extent
 139  * that covers the entire device
 140  */
 141 static struct extent_map *btree_get_extent(struct inode *inode,
 142                 struct page *page, size_t pg_offset, u64 start, u64 len,
 143                 int create)
 144 {
 145         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
 146         struct extent_map *em;
 147         int ret;
 148
 149         read_lock(&em_tree->lock);
 150         em = lookup_extent_mapping(em_tree, start, len);
 151         if (em) {
 152                 em->bdev =
 153                         BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
 154                 read_unlock(&em_tree->lock);
 155                 goto out;
 156         }
 157         read_unlock(&em_tree->lock);
 158
 159         em = alloc_extent_map();
 160         if (!em) {
 161                 em = ERR_PTR(-ENOMEM);
 162                 goto out;
 163         }
 164         em->start = 0;
 165         em->len = (u64)-1;
 166         em->block_len = (u64)-1;
 167         em->block_start = 0;
 168         em->bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
 169
 170         write_lock(&em_tree->lock);
 171         ret = add_extent_mapping(em_tree, em);
 172         if (ret == -EEXIST) {
 173                 u64 failed_start = em->start;
 174                 u64 failed_len = em->len;
 175
 176                 free_extent_map(em);
 177                 em = lookup_extent_mapping(em_tree, start, len);
 178                 if (em) {
 179                         ret = 0;
 180                 } else {
 181                         em = lookup_extent_mapping(em_tree, failed_start,
 182                                                    failed_len);
 183                         ret = -EIO;
 184                 }
 185         } else if (ret) {
 186                 free_extent_map(em);
 187                 em = NULL;
 188         }
 189         write_unlock(&em_tree->lock);
 190
 191         if (ret)
 192                 em = ERR_PTR(ret);
 193 out:
 194         return em;
 195 }
 196
 197 u32 btrfs_csum_data(struct btrfs_root *root, char *data, u32 seed, size_t len)
 198 {
 199         return crc32c(seed, data, len);
 200 }
 201
 202 void btrfs_csum_final(u32 crc, char *result)
 203 {
 204         put_unaligned_le32(~crc, result);
 205 }
 206
 207 /*
 208  * compute the csum for a btree block, and either verify it or write it
 209  * into the csum field of the block.
 210  */
 211 static int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf,
 212                            int verify)
 213 {
 214         u16 csum_size =
 215                 btrfs_super_csum_size(&root->fs_info->super_copy);
 216         char *result = NULL;
 217         unsigned long len;
 218         unsigned long cur_len;
 219         unsigned long offset = BTRFS_CSUM_SIZE;
 220         char *map_token = NULL;
 221         char *kaddr;
 222         unsigned long map_start;
 223         unsigned long map_len;
 224         int err;
 225         u32 crc = ~(u32)0;
 226         unsigned long inline_result;
 227
 228         len = buf->len - offset;
 229         while (len > 0) {
 230                 err = map_private_extent_buffer(buf, offset, 32,
 231                                         &map_token, &kaddr,
 232                                         &map_start, &map_len, KM_USER0);
 233                 if (err)
 234                         return 1;
 235                 cur_len = min(len, map_len - (offset - map_start));
 236                 crc = btrfs_csum_data(root, kaddr + offset - map_start,
 237                                       crc, cur_len);
 238                 len -= cur_len;
 239                 offset += cur_len;
 240                 unmap_extent_buffer(buf, map_token, KM_USER0);
 241         }
 242         if (csum_size > sizeof(inline_result)) {
 243                 result = kzalloc(csum_size * sizeof(char), GFP_NOFS);
 244                 if (!result)
 245                         return 1;
 246         } else {
 247                 result = (char *)&inline_result;
 248         }
 249
 250         btrfs_csum_final(crc, result);
 251
 252         if (verify) {
 253                 if (memcmp_extent_buffer(buf, result, 0, csum_size)) {
 254                         u32 val;
 255                         u32 found = 0;
 256                         memcpy(&found, result, csum_size);
 257
 258                         read_extent_buffer(buf, &val, 0, csum_size);
 259                         printk_ratelimited(KERN_INFO "btrfs: %s checksum verify "
 260                                        "failed on %llu wanted %X found %X "
 261                                        "level %d\n",
 262                                        root->fs_info->sb->s_id,
 263                                        (unsigned long long)buf->start, val, found,
 264                                        btrfs_header_level(buf));
 265                         if (result != (char *)&inline_result)
 266                                 kfree(result);
 267                         return 1;
 268                 }
 269         } else {
 270                 write_extent_buffer(buf, result, 0, csum_size);
 271         }
 272         if (result != (char *)&inline_result)
 273                 kfree(result);
 274         return 0;
 275 }
 276
 277 /*
 278  * we can't consider a given block up to date unless the transid of the
 279  * block matches the transid in the parent node's pointer.  This is how we
 280  * detect blocks that either didn't get written at all or got written
 281  * in the wrong place.
 282  */
 283 static int verify_parent_transid(struct extent_io_tree *io_tree,
 284                                  struct extent_buffer *eb, u64 parent_transid)
 285 {
 286         struct extent_state *cached_state = NULL;
 287         int ret;
 288
 289         if (!parent_transid || btrfs_header_generation(eb) == parent_transid)
 290                 return 0;
 291
 292         lock_extent_bits(io_tree, eb->start, eb->start + eb->len - 1,
 293                          0, &cached_state, GFP_NOFS);
 294         if (extent_buffer_uptodate(io_tree, eb, cached_state) &&
 295             btrfs_header_generation(eb) == parent_transid) {
 296                 ret = 0;
 297                 goto out;
 298         }
 299         printk_ratelimited("parent transid verify failed on %llu wanted %llu "
 300                        "found %llu\n",
 301                        (unsigned long long)eb->start,
 302                        (unsigned long long)parent_transid,
 303                        (unsigned long long)btrfs_header_generation(eb));
 304         ret = 1;
 305         clear_extent_buffer_uptodate(io_tree, eb, &cached_state);
 306 out:
 307         unlock_extent_cached(io_tree, eb->start, eb->start + eb->len - 1,
 308                              &cached_state, GFP_NOFS);
 309         return ret;
 310 }
 311
 312 /*
 313  * helper to read a given tree block, doing retries as required when
 314  * the checksums don't match and we have alternate mirrors to try.
 315  */
 316 static int btree_read_extent_buffer_pages(struct btrfs_root *root,
 317                                           struct extent_buffer *eb,
 318                                           u64 start, u64 parent_transid)
 319 {
 320         struct extent_io_tree *io_tree;
 321         int ret;
 322         int num_copies = 0;
 323         int mirror_num = 0;
 324
 325         clear_bit(EXTENT_BUFFER_CORRUPT, &eb->bflags);
 326         io_tree = &BTRFS_I(root->fs_info->btree_inode)->io_tree;
 327         while (1) {
 328                 ret = read_extent_buffer_pages(io_tree, eb, start, 1,
 329                                                btree_get_extent, mirror_num);
 330                 if (!ret &&
 331                     !verify_parent_transid(io_tree, eb, parent_transid))
 332                         return ret;
 333
 334                 /*
 335                  * This buffer's crc is fine, but its contents are corrupted, so
 336                  * there is no reason to read the other copies, they won't be
 337                  * any less wrong.
 338                  */
 339                 if (test_bit(EXTENT_BUFFER_CORRUPT, &eb->bflags))
 340                         return ret;
 341
 342                 num_copies = btrfs_num_copies(&root->fs_info->mapping_tree,
 343                                               eb->start, eb->len);
 344                 if (num_copies == 1)
 345                         return ret;
 346
 347                 mirror_num++;
 348                 if (mirror_num > num_copies)
 349                         return ret;
 350         }
 351         return -EIO;
 352 }
 353
 354 /*
 355  * checksum a dirty tree block before IO.  This has extra checks to make sure
 356  * we only fill in the checksum field in the first page of a multi-page block
 357  */
 358
 359 static int csum_dirty_buffer(struct btrfs_root *root, struct page *page)
 360 {
 361         struct extent_io_tree *tree;
 362         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
 363         u64 found_start;
 364         unsigned long len;
 365         struct extent_buffer *eb;
 366         int ret;
 367
 368         tree = &BTRFS_I(page->mapping->host)->io_tree;
 369
 370         if (page->private == EXTENT_PAGE_PRIVATE) {
 371                 WARN_ON(1);
 372                 goto out;
 373         }
 374         if (!page->private) {
 375                 WARN_ON(1);
 376                 goto out;
 377         }
 378         len = page->private >> 2;
 379         WARN_ON(len == 0);
 380
 381         eb = alloc_extent_buffer(tree, start, len, page);
 382         if (eb == NULL) {
 383                 WARN_ON(1);
 384                 goto out;
 385         }
 386         ret = btree_read_extent_buffer_pages(root, eb, start + PAGE_CACHE_SIZE,
 387                                              btrfs_header_generation(eb));
 388         BUG_ON(ret);
 389         WARN_ON(!btrfs_header_flag(eb, BTRFS_HEADER_FLAG_WRITTEN));
 390
 391         found_start = btrfs_header_bytenr(eb);
 392         if (found_start != start) {
 393                 WARN_ON(1);
 394                 goto err;
 395         }
 396         if (eb->first_page != page) {
 397                 WARN_ON(1);
 398                 goto err;
 399         }
 400         if (!PageUptodate(page)) {
 401                 WARN_ON(1);
 402                 goto err;
 403         }
 404         csum_tree_block(root, eb, 0);
 405 err:
 406         free_extent_buffer(eb);
 407 out:
 408         return 0;
 409 }
 410
 411 static int check_tree_block_fsid(struct btrfs_root *root,
 412                                  struct extent_buffer *eb)
 413 {
 414         struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices;
 415         u8 fsid[BTRFS_UUID_SIZE];
 416         int ret = 1;
 417
 418         read_extent_buffer(eb, fsid, (unsigned long)btrfs_header_fsid(eb),
 419                            BTRFS_FSID_SIZE);
 420         while (fs_devices) {
 421                 if (!memcmp(fsid, fs_devices->fsid, BTRFS_FSID_SIZE)) {
 422                         ret = 0;
 423                         break;
 424                 }
 425                 fs_devices = fs_devices->seed;
 426         }
 427         return ret;
 428 }
 429
 430 #define CORRUPT(reason, eb, root, slot)                         \
 431         printk(KERN_CRIT "btrfs: corrupt leaf, %s: block=%llu," \
 432                "root=%llu, slot=%d\n", reason,                  \
 433                (unsigned long long)btrfs_header_bytenr(eb),     \
 434                (unsigned long long)root->objectid, slot)
 435
 436 static noinline int check_leaf(struct btrfs_root *root,
 437                                struct extent_buffer *leaf)
 438 {
 439         struct btrfs_key key;
 440         struct btrfs_key leaf_key;
 441         u32 nritems = btrfs_header_nritems(leaf);
 442         int slot;
 443
 444         if (nritems == 0)
 445                 return 0;
 446
 447         /* Check the 0 item */
 448         if (btrfs_item_offset_nr(leaf, 0) + btrfs_item_size_nr(leaf, 0) !=
 449             BTRFS_LEAF_DATA_SIZE(root)) {
 450                 CORRUPT("invalid item offset size pair", leaf, root, 0);
 451                 return -EIO;
 452         }
 453
 454         /*
 455          * Check to make sure each items keys are in the correct order and their
 456          * offsets make sense.  We only have to loop through nritems-1 because
 457          * we check the current slot against the next slot, which verifies the
 458          * next slot's offset+size makes sense and that the current's slot
 459          * offset is correct.
 460          */
 461         for (slot = 0; slot < nritems - 1; slot++) {
 462                 btrfs_item_key_to_cpu(leaf, &leaf_key, slot);
 463                 btrfs_item_key_to_cpu(leaf, &key, slot + 1);
 464
 465                 /* Make sure the keys are in the right order */
 466                 if (btrfs_comp_cpu_keys(&leaf_key, &key) >= 0) {
 467                         CORRUPT("bad key order", leaf, root, slot);
 468                         return -EIO;
 469                 }
 470
 471                 /*
 472                  * Make sure the offset and ends are right, remember that the
 473                  * item data starts at the end of the leaf and grows towards the
 474                  * front.
 475                  */
 476                 if (btrfs_item_offset_nr(leaf, slot) !=
 477                         btrfs_item_end_nr(leaf, slot + 1)) {
 478                         CORRUPT("slot offset bad", leaf, root, slot);
 479                         return -EIO;
 480                 }
 481
 482                 /*
 483                  * Check to make sure that we don't point outside of the leaf,
 484                  * just incase all the items are consistent to eachother, but
 485                  * all point outside of the leaf.
 486                  */
 487                 if (btrfs_item_end_nr(leaf, slot) >
 488                     BTRFS_LEAF_DATA_SIZE(root)) {
 489                         CORRUPT("slot end outside of leaf", leaf, root, slot);
 490                         return -EIO;
 491                 }
 492         }
 493
 494         return 0;
 495 }
 496
 497 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 498 void btrfs_set_buffer_lockdep_class(struct extent_buffer *eb, int level)
 499 {
 500         lockdep_set_class_and_name(&eb->lock,
 501                            &btrfs_eb_class[level],
 502                            btrfs_eb_name[level]);
 503 }
 504 #endif
 505
 506 static int btree_readpage_end_io_hook(struct page *page, u64 start, u64 end,
 507                                struct extent_state *state)
 508 {
 509         struct extent_io_tree *tree;
 510         u64 found_start;
 511         int found_level;
 512         unsigned long len;
 513         struct extent_buffer *eb;
 514         struct btrfs_root *root = BTRFS_I(page->mapping->host)->root;
 515         int ret = 0;
 516
 517         tree = &BTRFS_I(page->mapping->host)->io_tree;
 518         if (page->private == EXTENT_PAGE_PRIVATE)
 519                 goto out;
 520         if (!page->private)
 521                 goto out;
 522
 523         len = page->private >> 2;
 524         WARN_ON(len == 0);
 525
 526         eb = alloc_extent_buffer(tree, start, len, page);
 527         if (eb == NULL) {
 528                 ret = -EIO;
 529                 goto out;
 530         }
 531
 532         found_start = btrfs_header_bytenr(eb);
 533         if (found_start != start) {
 534                 printk_ratelimited(KERN_INFO "btrfs bad tree block start "
 535                                "%llu %llu\n",
 536                                (unsigned long long)found_start,
 537                                (unsigned long long)eb->start);
 538                 ret = -EIO;
 539                 goto err;
 540         }
 541         if (eb->first_page != page) {
 542                 printk(KERN_INFO "btrfs bad first page %lu %lu\n",
 543                        eb->first_page->index, page->index);
 544                 WARN_ON(1);
 545                 ret = -EIO;
 546                 goto err;
 547         }
 548         if (check_tree_block_fsid(root, eb)) {
 549                 printk_ratelimited(KERN_INFO "btrfs bad fsid on block %llu\n",
 550                                (unsigned long long)eb->start);
 551                 ret = -EIO;
 552                 goto err;
 553         }
 554         found_level = btrfs_header_level(eb);
 555
 556         btrfs_set_buffer_lockdep_class(eb, found_level);
 557
 558         ret = csum_tree_block(root, eb, 1);
 559         if (ret) {
 560                 ret = -EIO;
 561                 goto err;
 562         }
 563
 564         /*
 565          * If this is a leaf block and it is corrupt, set the corrupt bit so
 566          * that we don't try and read the other copies of this block, just
 567          * return -EIO.
 568          */
 569         if (found_level == 0 && check_leaf(root, eb)) {
 570                 set_bit(EXTENT_BUFFER_CORRUPT, &eb->bflags);
 571                 ret = -EIO;
 572         }
 573
 574         end = min_t(u64, eb->len, PAGE_CACHE_SIZE);
 575         end = eb->start + end - 1;
 576 err:
 577         free_extent_buffer(eb);
 578 out:
 579         return ret;
 580 }
 581
 582 static void end_workqueue_bio(struct bio *bio, int err)
 583 {
 584         struct end_io_wq *end_io_wq = bio->bi_private;
 585         struct btrfs_fs_info *fs_info;
 586
 587         fs_info = end_io_wq->info;
 588         end_io_wq->error = err;
 589         end_io_wq->work.func = end_workqueue_fn;
 590         end_io_wq->work.flags = 0;
 591
 592         if (bio->bi_rw & REQ_WRITE) {
 593                 if (end_io_wq->metadata == 1)
 594                         btrfs_queue_worker(&fs_info->endio_meta_write_workers,
 595                                            &end_io_wq->work);
 596                 else if (end_io_wq->metadata == 2)
 597                         btrfs_queue_worker(&fs_info->endio_freespace_worker,
 598                                            &end_io_wq->work);
 599                 else
 600                         btrfs_queue_worker(&fs_info->endio_write_workers,
 601                                            &end_io_wq->work);
 602         } else {
 603                 if (end_io_wq->metadata)
 604                         btrfs_queue_worker(&fs_info->endio_meta_workers,
 605                                            &end_io_wq->work);
 606                 else
 607                         btrfs_queue_worker(&fs_info->endio_workers,
 608                                            &end_io_wq->work);
 609         }
 610 }
 611
 612 /*
 613  * For the metadata arg you want
 614  *
 615  * 0 - if data
 616  * 1 - if normal metadta
 617  * 2 - if writing to the free space cache area
 618  */
 619 int btrfs_bio_wq_end_io(struct btrfs_fs_info *info, struct bio *bio,
 620                         int metadata)
 621 {
 622         struct end_io_wq *end_io_wq;
 623         end_io_wq = kmalloc(sizeof(*end_io_wq), GFP_NOFS);
 624         if (!end_io_wq)
 625                 return -ENOMEM;
 626
 627         end_io_wq->private = bio->bi_private;
 628         end_io_wq->end_io = bio->bi_end_io;
 629         end_io_wq->info = info;
 630         end_io_wq->error = 0;
 631         end_io_wq->bio = bio;
 632         end_io_wq->metadata = metadata;
 633
 634         bio->bi_private = end_io_wq;
 635         bio->bi_end_io = end_workqueue_bio;
 636         return 0;
 637 }
 638
 639 unsigned long btrfs_async_submit_limit(struct btrfs_fs_info *info)
 640 {
 641         unsigned long limit = min_t(unsigned long,
 642                                     info->workers.max_workers,
 643                                     info->fs_devices->open_devices);
 644         return 256 * limit;
 645 }
 646
 647 static void run_one_async_start(struct btrfs_work *work)
 648 {
 649         struct async_submit_bio *async;
 650
 651         async = container_of(work, struct  async_submit_bio, work);
 652         async->submit_bio_start(async->inode, async->rw, async->bio,
 653                                async->mirror_num, async->bio_flags,
 654                                async->bio_offset);
 655 }
 656
 657 static void run_one_async_done(struct btrfs_work *work)
 658 {
 659         struct btrfs_fs_info *fs_info;
 660         struct async_submit_bio *async;
 661         int limit;
 662
 663         async = container_of(work, struct  async_submit_bio, work);
 664         fs_info = BTRFS_I(async->inode)->root->fs_info;
 665
 666         limit = btrfs_async_submit_limit(fs_info);
 667         limit = limit * 2 / 3;
 668
 669         atomic_dec(&fs_info->nr_async_submits);
 670
 671         if (atomic_read(&fs_info->nr_async_submits) < limit &&
 672             waitqueue_active(&fs_info->async_submit_wait))
 673                 wake_up(&fs_info->async_submit_wait);
 674
 675         async->submit_bio_done(async->inode, async->rw, async->bio,
 676                                async->mirror_num, async->bio_flags,
 677                                async->bio_offset);
 678 }
 679
 680 static void run_one_async_free(struct btrfs_work *work)
 681 {
 682         struct async_submit_bio *async;
 683
 684         async = container_of(work, struct  async_submit_bio, work);
 685         kfree(async);
 686 }
 687
 688 int btrfs_wq_submit_bio(struct btrfs_fs_info *fs_info, struct inode *inode,
 689                         int rw, struct bio *bio, int mirror_num,
 690                         unsigned long bio_flags,
 691                         u64 bio_offset,
 692                         extent_submit_bio_hook_t *submit_bio_start,
 693                         extent_submit_bio_hook_t *submit_bio_done)
 694 {
 695         struct async_submit_bio *async;
 696
 697         async = kmalloc(sizeof(*async), GFP_NOFS);
 698         if (!async)
 699                 return -ENOMEM;
 700
 701         async->inode = inode;
 702         async->rw = rw;
 703         async->bio = bio;
 704         async->mirror_num = mirror_num;
 705         async->submit_bio_start = submit_bio_start;
 706         async->submit_bio_done = submit_bio_done;
 707
 708         async->work.func = run_one_async_start;
 709         async->work.ordered_func = run_one_async_done;
 710         async->work.ordered_free = run_one_async_free;
 711
 712         async->work.flags = 0;
 713         async->bio_flags = bio_flags;
 714         async->bio_offset = bio_offset;
 715
 716         atomic_inc(&fs_info->nr_async_submits);
 717
 718         if (rw & REQ_SYNC)
 719                 btrfs_set_work_high_prio(&async->work);
 720
 721         btrfs_queue_worker(&fs_info->workers, &async->work);
 722
 723         while (atomic_read(&fs_info->async_submit_draining) &&
 724               atomic_read(&fs_info->nr_async_submits)) {
 725                 wait_event(fs_info->async_submit_wait,
 726                            (atomic_read(&fs_info->nr_async_submits) == 0));
 727         }
 728
 729         return 0;
 730 }
 731
 732 static int btree_csum_one_bio(struct bio *bio)
 733 {
 734         struct bio_vec *bvec = bio->bi_io_vec;
 735         int bio_index = 0;
 736         struct btrfs_root *root;
 737
 738         WARN_ON(bio->bi_vcnt <= 0);
 739         while (bio_index < bio->bi_vcnt) {
 740                 root = BTRFS_I(bvec->bv_page->mapping->host)->root;
 741                 csum_dirty_buffer(root, bvec->bv_page);
 742                 bio_index++;
 743                 bvec++;
 744         }
 745         return 0;
 746 }
 747
 748 static int __btree_submit_bio_start(struct inode *inode, int rw,
 749                                     struct bio *bio, int mirror_num,
 750                                     unsigned long bio_flags,
 751                                     u64 bio_offset)
 752 {
 753         /*
 754          * when we're called for a write, we're already in the async
 755          * submission context.  Just jump into btrfs_map_bio
 756          */
 757         btree_csum_one_bio(bio);
 758         return 0;
 759 }
 760
 761 static int __btree_submit_bio_done(struct inode *inode, int rw, struct bio *bio,
 762                                  int mirror_num, unsigned long bio_flags,
 763                                  u64 bio_offset)
 764 {
 765         /*
 766          * when we're called for a write, we're already in the async
 767          * submission context.  Just jump into btrfs_map_bio
 768          */
 769         return btrfs_map_bio(BTRFS_I(inode)->root, rw, bio, mirror_num, 1);
 770 }
 771
 772 static int btree_submit_bio_hook(struct inode *inode, int rw, struct bio *bio,
 773                                  int mirror_num, unsigned long bio_flags,
 774                                  u64 bio_offset)
 775 {
 776         int ret;
 777
 778         ret = btrfs_bio_wq_end_io(BTRFS_I(inode)->root->fs_info,
 779                                           bio, 1);
 780         BUG_ON(ret);
 781
 782         if (!(rw & REQ_WRITE)) {
 783                 /*
 784                  * called for a read, do the setup so that checksum validation
 785                  * can happen in the async kernel threads
 786                  */
 787                 return btrfs_map_bio(BTRFS_I(inode)->root, rw, bio,
 788                                      mirror_num, 0);
 789         }
 790
 791         /*
 792          * kthread helpers are used to submit writes so that checksumming
 793          * can happen in parallel across all CPUs
 794          */
 795         return btrfs_wq_submit_bio(BTRFS_I(inode)->root->fs_info,
 796                                    inode, rw, bio, mirror_num, 0,
 797                                    bio_offset,
 798                                    __btree_submit_bio_start,
 799                                    __btree_submit_bio_done);
 800 }
 801
 802 #ifdef CONFIG_MIGRATION
 803 static int btree_migratepage(struct address_space *mapping,
 804                         struct page *newpage, struct page *page)
 805 {
 806         /*
 807          * we can't safely write a btree page from here,
 808          * we haven't done the locking hook
 809          */
 810         if (PageDirty(page))
 811                 return -EAGAIN;
 812         /*
 813          * Buffers may be managed in a filesystem specific way.
 814          * We must have no buffers or drop them.
 815          */
 816         if (page_has_private(page) &&
 817             !try_to_release_page(page, GFP_KERNEL))
 818                 return -EAGAIN;
 819         return migrate_page(mapping, newpage, page);
 820 }
 821 #endif
 822
 823 static int btree_writepage(struct page *page, struct writeback_control *wbc)
 824 {
 825         struct extent_io_tree *tree;
 826         struct btrfs_root *root = BTRFS_I(page->mapping->host)->root;
 827         struct extent_buffer *eb;
 828         int was_dirty;
 829
 830         tree = &BTRFS_I(page->mapping->host)->io_tree;
 831         if (!(current->flags & PF_MEMALLOC)) {
 832                 return extent_write_full_page(tree, page,
 833                                               btree_get_extent, wbc);
 834         }
 835
 836         redirty_page_for_writepage(wbc, page);
 837         eb = btrfs_find_tree_block(root, page_offset(page), PAGE_CACHE_SIZE);
 838         WARN_ON(!eb);
 839
 840         was_dirty = test_and_set_bit(EXTENT_BUFFER_DIRTY, &eb->bflags);
 841         if (!was_dirty) {
 842                 spin_lock(&root->fs_info->delalloc_lock);
 843                 root->fs_info->dirty_metadata_bytes += PAGE_CACHE_SIZE;
 844                 spin_unlock(&root->fs_info->delalloc_lock);
 845         }
 846         free_extent_buffer(eb);
 847
 848         unlock_page(page);
 849         return 0;
 850 }
 851
 852 static int btree_writepages(struct address_space *mapping,
 853                             struct writeback_control *wbc)
 854 {
 855         struct extent_io_tree *tree;
 856         tree = &BTRFS_I(mapping->host)->io_tree;
 857         if (wbc->sync_mode == WB_SYNC_NONE) {
 858                 struct btrfs_root *root = BTRFS_I(mapping->host)->root;
 859                 u64 num_dirty;
 860                 unsigned long thresh = 32 * 1024 * 1024;
 861
 862                 if (wbc->for_kupdate)
 863                         return 0;
 864
 865                 /* this is a bit racy, but that's ok */
 866                 num_dirty = root->fs_info->dirty_metadata_bytes;
 867                 if (num_dirty < thresh)
 868                         return 0;
 869         }
 870         return extent_writepages(tree, mapping, btree_get_extent, wbc);
 871 }
 872
 873 static int btree_readpage(struct file *file, struct page *page)
 874 {
 875         struct extent_io_tree *tree;
 876         tree = &BTRFS_I(page->mapping->host)->io_tree;
 877         return extent_read_full_page(tree, page, btree_get_extent);
 878 }
 879
 880 static int btree_releasepage(struct page *page, gfp_t gfp_flags)
 881 {
 882         struct extent_io_tree *tree;
 883         struct extent_map_tree *map;
 884         int ret;
 885
 886         if (PageWriteback(page) || PageDirty(page))
 887                 return 0;
 888
 889         tree = &BTRFS_I(page->mapping->host)->io_tree;
 890         map = &BTRFS_I(page->mapping->host)->extent_tree;
 891
 892         ret = try_release_extent_state(map, tree, page, gfp_flags);
 893         if (!ret)
 894                 return 0;
 895
 896         ret = try_release_extent_buffer(tree, page);
 897         if (ret == 1) {
 898                 ClearPagePrivate(page);
 899                 set_page_private(page, 0);
 900                 page_cache_release(page);
 901         }
 902
 903         return ret;
 904 }
 905
 906 static void btree_invalidatepage(struct page *page, unsigned long offset)
 907 {
 908         struct extent_io_tree *tree;
 909         tree = &BTRFS_I(page->mapping->host)->io_tree;
 910         extent_invalidatepage(tree, page, offset);
 911         btree_releasepage(page, GFP_NOFS);
 912         if (PagePrivate(page)) {
 913                 printk(KERN_WARNING "btrfs warning page private not zero "
 914                        "on page %llu\n", (unsigned long long)page_offset(page));
 915                 ClearPagePrivate(page);
 916                 set_page_private(page, 0);
 917                 page_cache_release(page);
 918         }
 919 }
 920
 921 static const struct address_space_operations btree_aops = {
 922         .readpage       = btree_readpage,
 923         .writepage      = btree_writepage,
 924         .writepages     = btree_writepages,
 925         .releasepage    = btree_releasepage,
 926         .invalidatepage = btree_invalidatepage,
 927 #ifdef CONFIG_MIGRATION
 928         .migratepage    = btree_migratepage,
 929 #endif
 930 };
 931
 932 int readahead_tree_block(struct btrfs_root *root, u64 bytenr, u32 blocksize,
 933                          u64 parent_transid)
 934 {
 935         struct extent_buffer *buf = NULL;
 936         struct inode *btree_inode = root->fs_info->btree_inode;
 937         int ret = 0;
 938
 939         buf = btrfs_find_create_tree_block(root, bytenr, blocksize);
 940         if (!buf)
 941                 return 0;
 942         read_extent_buffer_pages(&BTRFS_I(btree_inode)->io_tree,
 943                                  buf, 0, 0, btree_get_extent, 0);
 944         free_extent_buffer(buf);
 945         return ret;
 946 }
 947
 948 struct extent_buffer *btrfs_find_tree_block(struct btrfs_root *root,
 949                                             u64 bytenr, u32 blocksize)
 950 {
 951         struct inode *btree_inode = root->fs_info->btree_inode;
 952         struct extent_buffer *eb;
 953         eb = find_extent_buffer(&BTRFS_I(btree_inode)->io_tree,
 954                                 bytenr, blocksize);
 955         return eb;
 956 }
 957
 958 struct extent_buffer *btrfs_find_create_tree_block(struct btrfs_root *root,
 959                                                  u64 bytenr, u32 blocksize)
 960 {
 961         struct inode *btree_inode = root->fs_info->btree_inode;
 962         struct extent_buffer *eb;
 963
 964         eb = alloc_extent_buffer(&BTRFS_I(btree_inode)->io_tree,
 965                                  bytenr, blocksize, NULL);
 966         return eb;
 967 }
 968
 969
 970 int btrfs_write_tree_block(struct extent_buffer *buf)
 971 {
 972         return filemap_fdatawrite_range(buf->first_page->mapping, buf->start,
 973                                         buf->start + buf->len - 1);
 974 }
 975
 976 int btrfs_wait_tree_block_writeback(struct extent_buffer *buf)
 977 {
 978         return filemap_fdatawait_range(buf->first_page->mapping,
 979                                        buf->start, buf->start + buf->len - 1);
 980 }
 981
 982 struct extent_buffer *read_tree_block(struct btrfs_root *root, u64 bytenr,
 983                                       u32 blocksize, u64 parent_transid)
 984 {
 985         struct extent_buffer *buf = NULL;
 986         int ret;
 987
 988         buf = btrfs_find_create_tree_block(root, bytenr, blocksize);
 989         if (!buf)
 990                 return NULL;
 991
 992         ret = btree_read_extent_buffer_pages(root, buf, 0, parent_transid);
 993
 994         if (ret == 0)
 995                 set_bit(EXTENT_BUFFER_UPTODATE, &buf->bflags);
 996         return buf;
 997
 998 }
 999
1000 int clean_tree_block(struct btrfs_trans_handle *trans, struct btrfs_root *root,
1001                      struct extent_buffer *buf)
1002 {
1003         struct inode *btree_inode = root->fs_info->btree_inode;
1004         if (btrfs_header_generation(buf) ==
1005             root->fs_info->running_transaction->transid) {
1006                 btrfs_assert_tree_locked(buf);
1007
1008                 if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &buf->bflags)) {
1009                         spin_lock(&root->fs_info->delalloc_lock);
1010                         if (root->fs_info->dirty_metadata_bytes >= buf->len)
1011                                 root->fs_info->dirty_metadata_bytes -= buf->len;
1012                         else
1013                                 WARN_ON(1);
1014                         spin_unlock(&root->fs_info->delalloc_lock);
1015                 }
1016
1017                 /* ugh, clear_extent_buffer_dirty needs to lock the page */
1018                 btrfs_set_lock_blocking(buf);
1019                 clear_extent_buffer_dirty(&BTRFS_I(btree_inode)->io_tree,
1020                                           buf);
1021         }
1022         return 0;
1023 }
1024
1025 static int __setup_root(u32 nodesize, u32 leafsize, u32 sectorsize,
1026                         u32 stripesize, struct btrfs_root *root,
1027                         struct btrfs_fs_info *fs_info,
1028                         u64 objectid)
1029 {
1030         root->node = NULL;
1031         root->commit_root = NULL;
1032         root->sectorsize = sectorsize;
1033         root->nodesize = nodesize;
1034         root->leafsize = leafsize;
1035         root->stripesize = stripesize;
1036         root->ref_cows = 0;
1037         root->track_dirty = 0;
1038         root->in_radix = 0;
1039         root->orphan_item_inserted = 0;
1040         root->orphan_cleanup_state = 0;
1041
1042         root->fs_info = fs_info;
1043         root->objectid = objectid;
1044         root->last_trans = 0;
1045         root->highest_objectid = 0;
1046         root->name = NULL;
1047         root->inode_tree = RB_ROOT;
1048         INIT_RADIX_TREE(&root->delayed_nodes_tree, GFP_ATOMIC);
1049         root->block_rsv = NULL;
1050         root->orphan_block_rsv = NULL;
1051
1052         INIT_LIST_HEAD(&root->dirty_list);
1053         INIT_LIST_HEAD(&root->orphan_list);
1054         INIT_LIST_HEAD(&root->root_list);
1055         spin_lock_init(&root->orphan_lock);
1056         spin_lock_init(&root->inode_lock);
1057         spin_lock_init(&root->accounting_lock);
1058         mutex_init(&root->objectid_mutex);
1059         mutex_init(&root->log_mutex);
1060         init_waitqueue_head(&root->log_writer_wait);
1061         init_waitqueue_head(&root->log_commit_wait[0]);
1062         init_waitqueue_head(&root->log_commit_wait[1]);
1063         atomic_set(&root->log_commit[0], 0);
1064         atomic_set(&root->log_commit[1], 0);
1065         atomic_set(&root->log_writers, 0);
1066         root->log_batch = 0;
1067         root->log_transid = 0;
1068         root->last_log_commit = 0;
1069         extent_io_tree_init(&root->dirty_log_pages,
1070                              fs_info->btree_inode->i_mapping);
1071
1072         memset(&root->root_key, 0, sizeof(root->root_key));
1073         memset(&root->root_item, 0, sizeof(root->root_item));
1074         memset(&root->defrag_progress, 0, sizeof(root->defrag_progress));
1075         memset(&root->root_kobj, 0, sizeof(root->root_kobj));
1076         root->defrag_trans_start = fs_info->generation;
1077         init_completion(&root->kobj_unregister);
1078         root->defrag_running = 0;
1079         root->root_key.objectid = objectid;
1080         root->anon_super.s_root = NULL;
1081         root->anon_super.s_dev = 0;
1082         INIT_LIST_HEAD(&root->anon_super.s_list);
1083         INIT_LIST_HEAD(&root->anon_super.s_instances);
1084         init_rwsem(&root->anon_super.s_umount);
1085
1086         return 0;
1087 }
1088
1089 static int find_and_setup_root(struct btrfs_root *tree_root,
1090                                struct btrfs_fs_info *fs_info,
1091                                u64 objectid,
1092                                struct btrfs_root *root)
1093 {
1094         int ret;
1095         u32 blocksize;
1096         u64 generation;
1097
1098         __setup_root(tree_root->nodesize, tree_root->leafsize,
1099                      tree_root->sectorsize, tree_root->stripesize,
1100                      root, fs_info, objectid);
1101         ret = btrfs_find_last_root(tree_root, objectid,
1102                                    &root->root_item, &root->root_key);
1103         if (ret > 0)
1104                 return -ENOENT;
1105         BUG_ON(ret);
1106
1107         generation = btrfs_root_generation(&root->root_item);
1108         blocksize = btrfs_level_size(root, btrfs_root_level(&root->root_item));
1109         root->node = read_tree_block(root, btrfs_root_bytenr(&root->root_item),
1110                                      blocksize, generation);
1111         if (!root->node || !btrfs_buffer_uptodate(root->node, generation)) {
1112                 free_extent_buffer(root->node);
1113                 return -EIO;
1114         }
1115         root->commit_root = btrfs_root_node(root);
1116         return 0;
1117 }
1118
1119 static struct btrfs_root *alloc_log_tree(struct btrfs_trans_handle *trans,
1120                                          struct btrfs_fs_info *fs_info)
1121 {
1122         struct btrfs_root *root;
1123         struct btrfs_root *tree_root = fs_info->tree_root;
1124         struct extent_buffer *leaf;
1125
1126         root = kzalloc(sizeof(*root), GFP_NOFS);
1127         if (!root)
1128                 return ERR_PTR(-ENOMEM);
1129
1130         __setup_root(tree_root->nodesize, tree_root->leafsize,
1131                      tree_root->sectorsize, tree_root->stripesize,
1132                      root, fs_info, BTRFS_TREE_LOG_OBJECTID);
1133
1134         root->root_key.objectid = BTRFS_TREE_LOG_OBJECTID;
1135         root->root_key.type = BTRFS_ROOT_ITEM_KEY;
1136         root->root_key.offset = BTRFS_TREE_LOG_OBJECTID;
1137         /*
1138          * log trees do not get reference counted because they go away
1139          * before a real commit is actually done.  They do store pointers
1140          * to file data extents, and those reference counts still get
1141          * updated (along with back refs to the log tree).
1142          */
1143         root->ref_cows = 0;
1144
1145         leaf = btrfs_alloc_free_block(trans, root, root->leafsize, 0,
1146                                       BTRFS_TREE_LOG_OBJECTID, NULL, 0, 0, 0);
1147         if (IS_ERR(leaf)) {
1148                 kfree(root);
1149                 return ERR_CAST(leaf);
1150         }
1151
1152         memset_extent_buffer(leaf, 0, 0, sizeof(struct btrfs_header));
1153         btrfs_set_header_bytenr(leaf, leaf->start);
1154         btrfs_set_header_generation(leaf, trans->transid);
1155         btrfs_set_header_backref_rev(leaf, BTRFS_MIXED_BACKREF_REV);
1156         btrfs_set_header_owner(leaf, BTRFS_TREE_LOG_OBJECTID);
1157         root->node = leaf;
1158
1159         write_extent_buffer(root->node, root->fs_info->fsid,
1160                             (unsigned long)btrfs_header_fsid(root->node),
1161                             BTRFS_FSID_SIZE);
1162         btrfs_mark_buffer_dirty(root->node);
1163         btrfs_tree_unlock(root->node);
1164         return root;
1165 }
1166
1167 int btrfs_init_log_root_tree(struct btrfs_trans_handle *trans,
1168                              struct btrfs_fs_info *fs_info)
1169 {
1170         struct btrfs_root *log_root;
1171
1172         log_root = alloc_log_tree(trans, fs_info);
1173         if (IS_ERR(log_root))
1174                 return PTR_ERR(log_root);
1175         WARN_ON(fs_info->log_root_tree);
1176         fs_info->log_root_tree = log_root;
1177         return 0;
1178 }
1179
1180 int btrfs_add_log_tree(struct btrfs_trans_handle *trans,
1181                        struct btrfs_root *root)
1182 {
1183         struct btrfs_root *log_root;
1184         struct btrfs_inode_item *inode_item;
1185
1186         log_root = alloc_log_tree(trans, root->fs_info);
1187         if (IS_ERR(log_root))
1188                 return PTR_ERR(log_root);
1189
1190         log_root->last_trans = trans->transid;
1191         log_root->root_key.offset = root->root_key.objectid;
1192
1193         inode_item = &log_root->root_item.inode;
1194         inode_item->generation = cpu_to_le64(1);
1195         inode_item->size = cpu_to_le64(3);
1196         inode_item->nlink = cpu_to_le32(1);
1197         inode_item->nbytes = cpu_to_le64(root->leafsize);
1198         inode_item->mode = cpu_to_le32(S_IFDIR | 0755);
1199
1200         btrfs_set_root_node(&log_root->root_item, log_root->node);
1201
1202         WARN_ON(root->log_root);
1203         root->log_root = log_root;
1204         root->log_transid = 0;
1205         root->last_log_commit = 0;
1206         return 0;
1207 }
1208
1209 struct btrfs_root *btrfs_read_fs_root_no_radix(struct btrfs_root *tree_root,
1210                                                struct btrfs_key *location)
1211 {
1212         struct btrfs_root *root;
1213         struct btrfs_fs_info *fs_info = tree_root->fs_info;
1214         struct btrfs_path *path;
1215         struct extent_buffer *l;
1216         u64 generation;
1217         u32 blocksize;
1218         int ret = 0;
1219
1220         root = kzalloc(sizeof(*root), GFP_NOFS);
1221         if (!root)
1222                 return ERR_PTR(-ENOMEM);
1223         if (location->offset == (u64)-1) {
1224                 ret = find_and_setup_root(tree_root, fs_info,
1225                                           location->objectid, root);
1226                 if (ret) {
1227                         kfree(root);
1228                         return ERR_PTR(ret);
1229                 }
1230                 goto out;
1231         }
1232
1233         __setup_root(tree_root->nodesize, tree_root->leafsize,
1234                      tree_root->sectorsize, tree_root->stripesize,
1235                      root, fs_info, location->objectid);
1236
1237         path = btrfs_alloc_path();
1238         if (!path) {
1239                 kfree(root);
1240                 return ERR_PTR(-ENOMEM);
1241         }
1242         ret = btrfs_search_slot(NULL, tree_root, location, path, 0, 0);
1243         if (ret == 0) {
1244                 l = path->nodes[0];
1245                 read_extent_buffer(l, &root->root_item,
1246                                 btrfs_item_ptr_offset(l, path->slots[0]),
1247                                 sizeof(root->root_item));
1248                 memcpy(&root->root_key, location, sizeof(*location));
1249         }
1250         btrfs_free_path(path);
1251         if (ret) {
1252                 kfree(root);
1253                 if (ret > 0)
1254                         ret = -ENOENT;
1255                 return ERR_PTR(ret);
1256         }
1257
1258         generation = btrfs_root_generation(&root->root_item);
1259         blocksize = btrfs_level_size(root, btrfs_root_level(&root->root_item));
1260         root->node = read_tree_block(root, btrfs_root_bytenr(&root->root_item),
1261                                      blocksize, generation);
1262         root->commit_root = btrfs_root_node(root);
1263         BUG_ON(!root->node);
1264 out:
1265         if (location->objectid != BTRFS_TREE_LOG_OBJECTID) {
1266                 root->ref_cows = 1;
1267                 btrfs_check_and_init_root_item(&root->root_item);
1268         }
1269
1270         return root;
1271 }
1272
1273 struct btrfs_root *btrfs_read_fs_root_no_name(struct btrfs_fs_info *fs_info,
1274                                               struct btrfs_key *location)
1275 {
1276         struct btrfs_root *root;
1277         int ret;
1278
1279         if (location->objectid == BTRFS_ROOT_TREE_OBJECTID)
1280                 return fs_info->tree_root;
1281         if (location->objectid == BTRFS_EXTENT_TREE_OBJECTID)
1282                 return fs_info->extent_root;
1283         if (location->objectid == BTRFS_CHUNK_TREE_OBJECTID)
1284                 return fs_info->chunk_root;
1285         if (location->objectid == BTRFS_DEV_TREE_OBJECTID)
1286                 return fs_info->dev_root;
1287         if (location->objectid == BTRFS_CSUM_TREE_OBJECTID)
1288                 return fs_info->csum_root;
1289 again:
1290         spin_lock(&fs_info->fs_roots_radix_lock);
1291         root = radix_tree_lookup(&fs_info->fs_roots_radix,
1292                                  (unsigned long)location->objectid);
1293         spin_unlock(&fs_info->fs_roots_radix_lock);
1294         if (root)
1295                 return root;
1296
1297         root = btrfs_read_fs_root_no_radix(fs_info->tree_root, location);
1298         if (IS_ERR(root))
1299                 return root;
1300
1301         root->free_ino_ctl = kzalloc(sizeof(*root->free_ino_ctl), GFP_NOFS);
1302         root->free_ino_pinned = kzalloc(sizeof(*root->free_ino_pinned),
1303                                         GFP_NOFS);
1304         if (!root->free_ino_pinned || !root->free_ino_ctl) {
1305                 ret = -ENOMEM;
1306                 goto fail;
1307         }
1308
1309         btrfs_init_free_ino_ctl(root);
1310         mutex_init(&root->fs_commit_mutex);
1311         spin_lock_init(&root->cache_lock);
1312         init_waitqueue_head(&root->cache_wait);
1313
1314         ret = set_anon_super(&root->anon_super, NULL);
1315         if (ret)
1316                 goto fail;
1317
1318         if (btrfs_root_refs(&root->root_item) == 0) {
1319                 ret = -ENOENT;
1320                 goto fail;
1321         }
1322
1323         ret = btrfs_find_orphan_item(fs_info->tree_root, location->objectid);
1324         if (ret < 0)
1325                 goto fail;
1326         if (ret == 0)
1327                 root->orphan_item_inserted = 1;
1328
1329         ret = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);
1330         if (ret)
1331                 goto fail;
1332
1333         spin_lock(&fs_info->fs_roots_radix_lock);
1334         ret = radix_tree_insert(&fs_info->fs_roots_radix,
1335                                 (unsigned long)root->root_key.objectid,
1336                                 root);
1337         if (ret == 0)
1338                 root->in_radix = 1;
1339
1340         spin_unlock(&fs_info->fs_roots_radix_lock);
1341         radix_tree_preload_end();
1342         if (ret) {
1343                 if (ret == -EEXIST) {
1344                         free_fs_root(root);
1345                         goto again;
1346                 }
1347                 goto fail;
1348         }
1349
1350         ret = btrfs_find_dead_roots(fs_info->tree_root,
1351                                     root->root_key.objectid);
1352         WARN_ON(ret);
1353         return root;
1354 fail:
1355         free_fs_root(root);
1356         return ERR_PTR(ret);
1357 }
1358
1359 static int btrfs_congested_fn(void *congested_data, int bdi_bits)
1360 {
1361         struct btrfs_fs_info *info = (struct btrfs_fs_info *)congested_data;
1362         int ret = 0;
1363         struct btrfs_device *device;
1364         struct backing_dev_info *bdi;
1365
1366         rcu_read_lock();
1367         list_for_each_entry_rcu(device, &info->fs_devices->devices, dev_list) {
1368                 if (!device->bdev)
1369                         continue;
1370                 bdi = blk_get_backing_dev_info(device->bdev);
1371                 if (bdi && bdi_congested(bdi, bdi_bits)) {
1372                         ret = 1;
1373                         break;
1374                 }
1375         }
1376         rcu_read_unlock();
1377         return ret;
1378 }
1379
1380 /*
1381  * If this fails, caller must call bdi_destroy() to get rid of the
1382  * bdi again.
1383  */
1384 static int setup_bdi(struct btrfs_fs_info *info, struct backing_dev_info *bdi)
1385 {
1386         int err;
1387
1388         bdi->capabilities = BDI_CAP_MAP_COPY;
1389         err = bdi_setup_and_register(bdi, "btrfs", BDI_CAP_MAP_COPY);
1390         if (err)
1391                 return err;
1392
1393         bdi->ra_pages   = default_backing_dev_info.ra_pages;
1394         bdi->congested_fn       = btrfs_congested_fn;
1395         bdi->congested_data     = info;
1396         return 0;
1397 }
1398
1399 static int bio_ready_for_csum(struct bio *bio)
1400 {
1401         u64 length = 0;
1402         u64 buf_len = 0;
1403         u64 start = 0;
1404         struct page *page;
1405         struct extent_io_tree *io_tree = NULL;
1406         struct bio_vec *bvec;
1407         int i;
1408         int ret;
1409
1410         bio_for_each_segment(bvec, bio, i) {
1411                 page = bvec->bv_page;
1412                 if (page->private == EXTENT_PAGE_PRIVATE) {
1413                         length += bvec->bv_len;
1414                         continue;
1415                 }
1416                 if (!page->private) {
1417                         length += bvec->bv_len;
1418                         continue;
1419                 }
1420                 length = bvec->bv_len;
1421                 buf_len = page->private >> 2;
1422                 start = page_offset(page) + bvec->bv_offset;
1423                 io_tree = &BTRFS_I(page->mapping->host)->io_tree;
1424         }
1425         /* are we fully contained in this bio? */
1426         if (buf_len <= length)
1427                 return 1;
1428
1429         ret = extent_range_uptodate(io_tree, start + length,
1430                                     start + buf_len - 1);
1431         return ret;
1432 }
1433
1434 /*
1435  * called by the kthread helper functions to finally call the bio end_io
1436  * functions.  This is where read checksum verification actually happens
1437  */
1438 static void end_workqueue_fn(struct btrfs_work *work)
1439 {
1440         struct bio *bio;
1441         struct end_io_wq *end_io_wq;
1442         struct btrfs_fs_info *fs_info;
1443         int error;
1444
1445         end_io_wq = container_of(work, struct end_io_wq, work);
1446         bio = end_io_wq->bio;
1447         fs_info = end_io_wq->info;
1448
1449         /* metadata bio reads are special because the whole tree block must
1450          * be checksummed at once.  This makes sure the entire block is in
1451          * ram and up to date before trying to verify things.  For
1452          * blocksize <= pagesize, it is basically a noop
1453          */
1454         if (!(bio->bi_rw & REQ_WRITE) && end_io_wq->metadata &&
1455             !bio_ready_for_csum(bio)) {
1456                 btrfs_queue_worker(&fs_info->endio_meta_workers,
1457                                    &end_io_wq->work);
1458                 return;
1459         }
1460         error = end_io_wq->error;
1461         bio->bi_private = end_io_wq->private;
1462         bio->bi_end_io = end_io_wq->end_io;
1463         kfree(end_io_wq);
1464         bio_endio(bio, error);
1465 }
1466
1467 static int cleaner_kthread(void *arg)
1468 {
1469         struct btrfs_root *root = arg;
1470
1471         do {
1472                 vfs_check_frozen(root->fs_info->sb, SB_FREEZE_WRITE);
1473
1474                 if (!(root->fs_info->sb->s_flags & MS_RDONLY) &&
1475                     mutex_trylock(&root->fs_info->cleaner_mutex)) {
1476                         btrfs_run_delayed_iputs(root);
1477                         btrfs_clean_old_snapshots(root);
1478                         mutex_unlock(&root->fs_info->cleaner_mutex);
1479                         btrfs_run_defrag_inodes(root->fs_info);
1480                 }
1481
1482                 if (freezing(current)) {
1483                         refrigerator();
1484                 } else {
1485                         set_current_state(TASK_INTERRUPTIBLE);
1486                         if (!kthread_should_stop())
1487                                 schedule();
1488                         __set_current_state(TASK_RUNNING);
1489                 }
1490         } while (!kthread_should_stop());
1491         return 0;
1492 }
1493
1494 static int transaction_kthread(void *arg)
1495 {
1496         struct btrfs_root *root = arg;
1497         struct btrfs_trans_handle *trans;
1498         struct btrfs_transaction *cur;
1499         u64 transid;
1500         unsigned long now;
1501         unsigned long delay;
1502         int ret;
1503
1504         do {
1505                 delay = HZ * 30;
1506                 vfs_check_frozen(root->fs_info->sb, SB_FREEZE_WRITE);
1507                 mutex_lock(&root->fs_info->transaction_kthread_mutex);
1508
1509                 spin_lock(&root->fs_info->trans_lock);
1510                 cur = root->fs_info->running_transaction;
1511                 if (!cur) {
1512                         spin_unlock(&root->fs_info->trans_lock);
1513                         goto sleep;
1514                 }
1515
1516                 now = get_seconds();
1517                 if (!cur->blocked &&
1518                     (now < cur->start_time || now - cur->start_time < 30)) {
1519                         spin_unlock(&root->fs_info->trans_lock);
1520                         delay = HZ * 5;
1521                         goto sleep;
1522                 }
1523                 transid = cur->transid;
1524                 spin_unlock(&root->fs_info->trans_lock);
1525
1526                 trans = btrfs_join_transaction(root);
1527                 BUG_ON(IS_ERR(trans));
1528                 if (transid == trans->transid) {
1529                         ret = btrfs_commit_transaction(trans, root);
1530                         BUG_ON(ret);
1531                 } else {
1532                         btrfs_end_transaction(trans, root);
1533                 }
1534 sleep:
1535                 wake_up_process(root->fs_info->cleaner_kthread);
1536                 mutex_unlock(&root->fs_info->transaction_kthread_mutex);
1537
1538                 if (freezing(current)) {
1539                         refrigerator();
1540                 } else {
1541                         set_current_state(TASK_INTERRUPTIBLE);
1542                         if (!kthread_should_stop() &&
1543                             !btrfs_transaction_blocked(root->fs_info))
1544                                 schedule_timeout(delay);
1545                         __set_current_state(TASK_RUNNING);
1546                 }
1547         } while (!kthread_should_stop());
1548         return 0;
1549 }
1550
1551 struct btrfs_root *open_ctree(struct super_block *sb,
1552                               struct btrfs_fs_devices *fs_devices,
1553                               char *options)
1554 {
1555         u32 sectorsize;
1556         u32 nodesize;
1557         u32 leafsize;
1558         u32 blocksize;
1559         u32 stripesize;
1560         u64 generation;
1561         u64 features;
1562         struct btrfs_key location;
1563         struct buffer_head *bh;
1564         struct btrfs_root *extent_root = kzalloc(sizeof(struct btrfs_root),
1565                                                  GFP_NOFS);
1566         struct btrfs_root *csum_root = kzalloc(sizeof(struct btrfs_root),
1567                                                  GFP_NOFS);
1568         struct btrfs_root *tree_root = btrfs_sb(sb);
1569         struct btrfs_fs_info *fs_info = NULL;
1570         struct btrfs_root *chunk_root = kzalloc(sizeof(struct btrfs_root),
1571                                                 GFP_NOFS);
1572         struct btrfs_root *dev_root = kzalloc(sizeof(struct btrfs_root),
1573                                               GFP_NOFS);
1574         struct btrfs_root *log_tree_root;
1575
1576         int ret;
1577         int err = -EINVAL;
1578
1579         struct btrfs_super_block *disk_super;
1580
1581         if (!extent_root || !tree_root || !tree_root->fs_info ||
1582             !chunk_root || !dev_root || !csum_root) {
1583                 err = -ENOMEM;
1584                 goto fail;
1585         }
1586         fs_info = tree_root->fs_info;
1587
1588         ret = init_srcu_struct(&fs_info->subvol_srcu);
1589         if (ret) {
1590                 err = ret;
1591                 goto fail;
1592         }
1593
1594         ret = setup_bdi(fs_info, &fs_info->bdi);
1595         if (ret) {
1596                 err = ret;
1597                 goto fail_srcu;
1598         }
1599
1600         fs_info->btree_inode = new_inode(sb);
1601         if (!fs_info->btree_inode) {
1602                 err = -ENOMEM;
1603                 goto fail_bdi;
1604         }
1605
1606         fs_info->btree_inode->i_mapping->flags &= ~__GFP_FS;
1607
1608         INIT_RADIX_TREE(&fs_info->fs_roots_radix, GFP_ATOMIC);
1609         INIT_LIST_HEAD(&fs_info->trans_list);
1610         INIT_LIST_HEAD(&fs_info->dead_roots);
1611         INIT_LIST_HEAD(&fs_info->delayed_iputs);
1612         INIT_LIST_HEAD(&fs_info->hashers);
1613         INIT_LIST_HEAD(&fs_info->delalloc_inodes);
1614         INIT_LIST_HEAD(&fs_info->ordered_operations);
1615         INIT_LIST_HEAD(&fs_info->caching_block_groups);
1616         spin_lock_init(&fs_info->delalloc_lock);
1617         spin_lock_init(&fs_info->trans_lock);
1618         spin_lock_init(&fs_info->ref_cache_lock);
1619         spin_lock_init(&fs_info->fs_roots_radix_lock);
1620         spin_lock_init(&fs_info->delayed_iput_lock);
1621         spin_lock_init(&fs_info->defrag_inodes_lock);
1622         mutex_init(&fs_info->reloc_mutex);
1623
1624         init_completion(&fs_info->kobj_unregister);
1625         fs_info->tree_root = tree_root;
1626         fs_info->extent_root = extent_root;
1627         fs_info->csum_root = csum_root;
1628         fs_info->chunk_root = chunk_root;
1629         fs_info->dev_root = dev_root;
1630         fs_info->fs_devices = fs_devices;
1631         INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);
1632         INIT_LIST_HEAD(&fs_info->space_info);
1633         btrfs_mapping_init(&fs_info->mapping_tree);
1634         btrfs_init_block_rsv(&fs_info->global_block_rsv);
1635         btrfs_init_block_rsv(&fs_info->delalloc_block_rsv);
1636         btrfs_init_block_rsv(&fs_info->trans_block_rsv);
1637         btrfs_init_block_rsv(&fs_info->chunk_block_rsv);
1638         btrfs_init_block_rsv(&fs_info->empty_block_rsv);
1639         INIT_LIST_HEAD(&fs_info->durable_block_rsv_list);
1640         mutex_init(&fs_info->durable_block_rsv_mutex);
1641         atomic_set(&fs_info->nr_async_submits, 0);
1642         atomic_set(&fs_info->async_delalloc_pages, 0);
1643         atomic_set(&fs_info->async_submit_draining, 0);
1644         atomic_set(&fs_info->nr_async_bios, 0);
1645         atomic_set(&fs_info->defrag_running, 0);
1646         fs_info->sb = sb;
1647         fs_info->max_inline = 8192 * 1024;
1648         fs_info->metadata_ratio = 0;
1649         fs_info->defrag_inodes = RB_ROOT;
1650         fs_info->trans_no_join = 0;
1651
1652         fs_info->thread_pool_size = min_t(unsigned long,
1653                                           num_online_cpus() + 2, 8);
1654
1655         INIT_LIST_HEAD(&fs_info->ordered_extents);
1656         spin_lock_init(&fs_info->ordered_extent_lock);
1657         fs_info->delayed_root = kmalloc(sizeof(struct btrfs_delayed_root),
1658                                         GFP_NOFS);
1659         if (!fs_info->delayed_root) {
1660                 err = -ENOMEM;
1661                 goto fail_iput;
1662         }
1663         btrfs_init_delayed_root(fs_info->delayed_root);
1664
1665         mutex_init(&fs_info->scrub_lock);
1666         atomic_set(&fs_info->scrubs_running, 0);
1667         atomic_set(&fs_info->scrub_pause_req, 0);
1668         atomic_set(&fs_info->scrubs_paused, 0);
1669         atomic_set(&fs_info->scrub_cancel_req, 0);
1670         init_waitqueue_head(&fs_info->scrub_pause_wait);
1671         init_rwsem(&fs_info->scrub_super_lock);
1672         fs_info->scrub_workers_refcnt = 0;
1673
1674         sb->s_blocksize = 4096;
1675         sb->s_blocksize_bits = blksize_bits(4096);
1676         sb->s_bdi = &fs_info->bdi;
1677
1678         fs_info->btree_inode->i_ino = BTRFS_BTREE_INODE_OBJECTID;
1679         fs_info->btree_inode->i_nlink = 1;
1680         /*
1681          * we set the i_size on the btree inode to the max possible int.
1682          * the real end of the address space is determined by all of
1683          * the devices in the system
1684          */
1685         fs_info->btree_inode->i_size = OFFSET_MAX;
1686         fs_info->btree_inode->i_mapping->a_ops = &btree_aops;
1687         fs_info->btree_inode->i_mapping->backing_dev_info = &fs_info->bdi;
1688
1689         RB_CLEAR_NODE(&BTRFS_I(fs_info->btree_inode)->rb_node);
1690         extent_io_tree_init(&BTRFS_I(fs_info->btree_inode)->io_tree,
1691                              fs_info->btree_inode->i_mapping);
1692         extent_map_tree_init(&BTRFS_I(fs_info->btree_inode)->extent_tree);
1693
1694         BTRFS_I(fs_info->btree_inode)->io_tree.ops = &btree_extent_io_ops;
1695
1696         BTRFS_I(fs_info->btree_inode)->root = tree_root;
1697         memset(&BTRFS_I(fs_info->btree_inode)->location, 0,
1698                sizeof(struct btrfs_key));
1699         BTRFS_I(fs_info->btree_inode)->dummy_inode = 1;
1700         insert_inode_hash(fs_info->btree_inode);
1701
1702         spin_lock_init(&fs_info->block_group_cache_lock);
1703         fs_info->block_group_cache_tree = RB_ROOT;
1704
1705         extent_io_tree_init(&fs_info->freed_extents[0],
1706                              fs_info->btree_inode->i_mapping);
1707         extent_io_tree_init(&fs_info->freed_extents[1],
1708                              fs_info->btree_inode->i_mapping);
1709         fs_info->pinned_extents = &fs_info->freed_extents[0];
1710         fs_info->do_barriers = 1;
1711
1712
1713         mutex_init(&fs_info->ordered_operations_mutex);
1714         mutex_init(&fs_info->tree_log_mutex);
1715         mutex_init(&fs_info->chunk_mutex);
1716         mutex_init(&fs_info->transaction_kthread_mutex);
1717         mutex_init(&fs_info->cleaner_mutex);
1718         mutex_init(&fs_info->volume_mutex);
1719         init_rwsem(&fs_info->extent_commit_sem);
1720         init_rwsem(&fs_info->cleanup_work_sem);
1721         init_rwsem(&fs_info->subvol_sem);
1722
1723         btrfs_init_free_cluster(&fs_info->meta_alloc_cluster);
1724         btrfs_init_free_cluster(&fs_info->data_alloc_cluster);
1725
1726         init_waitqueue_head(&fs_info->transaction_throttle);
1727         init_waitqueue_head(&fs_info->transaction_wait);
1728         init_waitqueue_head(&fs_info->transaction_blocked_wait);
1729         init_waitqueue_head(&fs_info->async_submit_wait);
1730
1731         __setup_root(4096, 4096, 4096, 4096, tree_root,
1732                      fs_info, BTRFS_ROOT_TREE_OBJECTID);
1733
1734         bh = btrfs_read_dev_super(fs_devices->latest_bdev);
1735         if (!bh) {
1736                 err = -EINVAL;
1737                 goto fail_alloc;
1738         }
1739
1740         memcpy(&fs_info->super_copy, bh->b_data, sizeof(fs_info->super_copy));
1741         memcpy(&fs_info->super_for_commit, &fs_info->super_copy,
1742                sizeof(fs_info->super_for_commit));
1743         brelse(bh);
1744
1745         memcpy(fs_info->fsid, fs_info->super_copy.fsid, BTRFS_FSID_SIZE);
1746
1747         disk_super = &fs_info->super_copy;
1748         if (!btrfs_super_root(disk_super))
1749                 goto fail_alloc;
1750
1751         /* check FS state, whether FS is broken. */
1752         fs_info->fs_state |= btrfs_super_flags(disk_super);
1753
1754         btrfs_check_super_valid(fs_info, sb->s_flags & MS_RDONLY);
1755
1756         /*
1757          * In the long term, we'll store the compression type in the super
1758          * block, and it'll be used for per file compression control.
1759          */
1760         fs_info->compress_type = BTRFS_COMPRESS_ZLIB;
1761
1762         ret = btrfs_parse_options(tree_root, options);
1763         if (ret) {
1764                 err = ret;
1765                 goto fail_alloc;
1766         }
1767
1768         features = btrfs_super_incompat_flags(disk_super) &
1769                 ~BTRFS_FEATURE_INCOMPAT_SUPP;
1770         if (features) {
1771                 printk(KERN_ERR "BTRFS: couldn't mount because of "
1772                        "unsupported optional features (%Lx).\n",
1773                        (unsigned long long)features);
1774                 err = -EINVAL;
1775                 goto fail_alloc;
1776         }
1777
1778         features = btrfs_super_incompat_flags(disk_super);
1779         features |= BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF;
1780         if (tree_root->fs_info->compress_type & BTRFS_COMPRESS_LZO)
1781                 features |= BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO;
1782         btrfs_set_super_incompat_flags(disk_super, features);
1783
1784         features = btrfs_super_compat_ro_flags(disk_super) &
1785                 ~BTRFS_FEATURE_COMPAT_RO_SUPP;
1786         if (!(sb->s_flags & MS_RDONLY) && features) {
1787                 printk(KERN_ERR "BTRFS: couldn't mount RDWR because of "
1788                        "unsupported option features (%Lx).\n",
1789                        (unsigned long long)features);
1790                 err = -EINVAL;
1791                 goto fail_alloc;
1792         }
1793
1794         btrfs_init_workers(&fs_info->generic_worker,
1795                            "genwork", 1, NULL);
1796
1797         btrfs_init_workers(&fs_info->workers, "worker",
1798                            fs_info->thread_pool_size,
1799                            &fs_info->generic_worker);
1800
1801         btrfs_init_workers(&fs_info->delalloc_workers, "delalloc",
1802                            fs_info->thread_pool_size,
1803                            &fs_info->generic_worker);
1804
1805         btrfs_init_workers(&fs_info->submit_workers, "submit",
1806                            min_t(u64, fs_devices->num_devices,
1807                            fs_info->thread_pool_size),
1808                            &fs_info->generic_worker);
1809
1810         /* a higher idle thresh on the submit workers makes it much more
1811          * likely that bios will be send down in a sane order to the
1812          * devices
1813          */
1814         fs_info->submit_workers.idle_thresh = 64;
1815
1816         fs_info->workers.idle_thresh = 16;
1817         fs_info->workers.ordered = 1;
1818
1819         fs_info->delalloc_workers.idle_thresh = 2;
1820         fs_info->delalloc_workers.ordered = 1;
1821
1822         btrfs_init_workers(&fs_info->fixup_workers, "fixup", 1,
1823                            &fs_info->generic_worker);
1824         btrfs_init_workers(&fs_info->endio_workers, "endio",
1825                            fs_info->thread_pool_size,
1826                            &fs_info->generic_worker);
1827         btrfs_init_workers(&fs_info->endio_meta_workers, "endio-meta",
1828                            fs_info->thread_pool_size,
1829                            &fs_info->generic_worker);
1830         btrfs_init_workers(&fs_info->endio_meta_write_workers,
1831                            "endio-meta-write", fs_info->thread_pool_size,
1832                            &fs_info->generic_worker);
1833         btrfs_init_workers(&fs_info->endio_write_workers, "endio-write",
1834                            fs_info->thread_pool_size,
1835                            &fs_info->generic_worker);
1836         btrfs_init_workers(&fs_info->endio_freespace_worker, "freespace-write",
1837                            1, &fs_info->generic_worker);
1838         btrfs_init_workers(&fs_info->delayed_workers, "delayed-meta",
1839                            fs_info->thread_pool_size,
1840                            &fs_info->generic_worker);
1841
1842         /*
1843          * endios are largely parallel and should have a very
1844          * low idle thresh
1845          */
1846         fs_info->endio_workers.idle_thresh = 4;
1847         fs_info->endio_meta_workers.idle_thresh = 4;
1848
1849         fs_info->endio_write_workers.idle_thresh = 2;
1850         fs_info->endio_meta_write_workers.idle_thresh = 2;
1851
1852         btrfs_start_workers(&fs_info->workers, 1);
1853         btrfs_start_workers(&fs_info->generic_worker, 1);
1854         btrfs_start_workers(&fs_info->submit_workers, 1);
1855         btrfs_start_workers(&fs_info->delalloc_workers, 1);
1856         btrfs_start_workers(&fs_info->fixup_workers, 1);
1857         btrfs_start_workers(&fs_info->endio_workers, 1);
1858         btrfs_start_workers(&fs_info->endio_meta_workers, 1);
1859         btrfs_start_workers(&fs_info->endio_meta_write_workers, 1);
1860         btrfs_start_workers(&fs_info->endio_write_workers, 1);
1861         btrfs_start_workers(&fs_info->endio_freespace_worker, 1);
1862         btrfs_start_workers(&fs_info->delayed_workers, 1);
1863
1864         fs_info->bdi.ra_pages *= btrfs_super_num_devices(disk_super);
1865         fs_info->bdi.ra_pages = max(fs_info->bdi.ra_pages,
1866                                     4 * 1024 * 1024 / PAGE_CACHE_SIZE);
1867
1868         nodesize = btrfs_super_nodesize(disk_super);
1869         leafsize = btrfs_super_leafsize(disk_super);
1870         sectorsize = btrfs_super_sectorsize(disk_super);
1871         stripesize = btrfs_super_stripesize(disk_super);
1872         tree_root->nodesize = nodesize;
1873         tree_root->leafsize = leafsize;
1874         tree_root->sectorsize = sectorsize;
1875         tree_root->stripesize = stripesize;
1876
1877         sb->s_blocksize = sectorsize;
1878         sb->s_blocksize_bits = blksize_bits(sectorsize);
1879
1880         if (strncmp((char *)(&disk_super->magic), BTRFS_MAGIC,
1881                     sizeof(disk_super->magic))) {
1882                 printk(KERN_INFO "btrfs: valid FS not found on %s\n", sb->s_id);
1883                 goto fail_sb_buffer;
1884         }
1885
1886         mutex_lock(&fs_info->chunk_mutex);
1887         ret = btrfs_read_sys_array(tree_root);
1888         mutex_unlock(&fs_info->chunk_mutex);
1889         if (ret) {
1890                 printk(KERN_WARNING "btrfs: failed to read the system "
1891                        "array on %s\n", sb->s_id);
1892                 goto fail_sb_buffer;
1893         }
1894
1895         blocksize = btrfs_level_size(tree_root,
1896                                      btrfs_super_chunk_root_level(disk_super));
1897         generation = btrfs_super_chunk_root_generation(disk_super);
1898
1899         __setup_root(nodesize, leafsize, sectorsize, stripesize,
1900                      chunk_root, fs_info, BTRFS_CHUNK_TREE_OBJECTID);
1901
1902         chunk_root->node = read_tree_block(chunk_root,
1903                                            btrfs_super_chunk_root(disk_super),
1904                                            blocksize, generation);
1905         BUG_ON(!chunk_root->node);
1906         if (!test_bit(EXTENT_BUFFER_UPTODATE, &chunk_root->node->bflags)) {
1907                 printk(KERN_WARNING "btrfs: failed to read chunk root on %s\n",
1908                        sb->s_id);
1909                 goto fail_chunk_root;
1910         }
1911         btrfs_set_root_node(&chunk_root->root_item, chunk_root->node);
1912         chunk_root->commit_root = btrfs_root_node(chunk_root);
1913
1914         read_extent_buffer(chunk_root->node, fs_info->chunk_tree_uuid,
1915            (unsigned long)btrfs_header_chunk_tree_uuid(chunk_root->node),
1916            BTRFS_UUID_SIZE);
1917
1918         mutex_lock(&fs_info->chunk_mutex);
1919         ret = btrfs_read_chunk_tree(chunk_root);
1920         mutex_unlock(&fs_info->chunk_mutex);
1921         if (ret) {
1922                 printk(KERN_WARNING "btrfs: failed to read chunk tree on %s\n",
1923                        sb->s_id);
1924                 goto fail_chunk_root;
1925         }
1926
1927         btrfs_close_extra_devices(fs_devices);
1928
1929         blocksize = btrfs_level_size(tree_root,
1930                                      btrfs_super_root_level(disk_super));
1931         generation = btrfs_super_generation(disk_super);
1932
1933         tree_root->node = read_tree_block(tree_root,
1934                                           btrfs_super_root(disk_super),
1935                                           blocksize, generation);
1936         if (!tree_root->node)
1937                 goto fail_chunk_root;
1938         if (!test_bit(EXTENT_BUFFER_UPTODATE, &tree_root->node->bflags)) {
1939                 printk(KERN_WARNING "btrfs: failed to read tree root on %s\n",
1940                        sb->s_id);
1941                 goto fail_tree_root;
1942         }
1943         btrfs_set_root_node(&tree_root->root_item, tree_root->node);
1944         tree_root->commit_root = btrfs_root_node(tree_root);
1945
1946         ret = find_and_setup_root(tree_root, fs_info,
1947                                   BTRFS_EXTENT_TREE_OBJECTID, extent_root);
1948         if (ret)
1949                 goto fail_tree_root;
1950         extent_root->track_dirty = 1;
1951
1952         ret = find_and_setup_root(tree_root, fs_info,
1953                                   BTRFS_DEV_TREE_OBJECTID, dev_root);
1954         if (ret)
1955                 goto fail_extent_root;
1956         dev_root->track_dirty = 1;
1957
1958         ret = find_and_setup_root(tree_root, fs_info,
1959                                   BTRFS_CSUM_TREE_OBJECTID, csum_root);
1960         if (ret)
1961                 goto fail_dev_root;
1962
1963         csum_root->track_dirty = 1;
1964
1965         fs_info->generation = generation;
1966         fs_info->last_trans_committed = generation;
1967         fs_info->data_alloc_profile = (u64)-1;
1968         fs_info->metadata_alloc_profile = (u64)-1;
1969         fs_info->system_alloc_profile = fs_info->metadata_alloc_profile;
1970
1971         ret = btrfs_init_space_info(fs_info);
1972         if (ret) {
1973                 printk(KERN_ERR "Failed to initial space info: %d\n", ret);
1974                 goto fail_block_groups;
1975         }
1976
1977         ret = btrfs_read_block_groups(extent_root);
1978         if (ret) {
1979                 printk(KERN_ERR "Failed to read block groups: %d\n", ret);
1980                 goto fail_block_groups;
1981         }
1982
1983         fs_info->cleaner_kthread = kthread_run(cleaner_kthread, tree_root,
1984                                                "btrfs-cleaner");
1985         if (IS_ERR(fs_info->cleaner_kthread))
1986                 goto fail_block_groups;
1987
1988         fs_info->transaction_kthread = kthread_run(transaction_kthread,
1989                                                    tree_root,
1990                                                    "btrfs-transaction");
1991         if (IS_ERR(fs_info->transaction_kthread))
1992                 goto fail_cleaner;
1993
1994         if (!btrfs_test_opt(tree_root, SSD) &&
1995             !btrfs_test_opt(tree_root, NOSSD) &&
1996             !fs_info->fs_devices->rotating) {
1997                 printk(KERN_INFO "Btrfs detected SSD devices, enabling SSD "
1998                        "mode\n");
1999                 btrfs_set_opt(fs_info->mount_opt, SSD);
2000         }
2001
2002         /* do not make disk changes in broken FS */
2003         if (btrfs_super_log_root(disk_super) != 0 &&
2004             !(fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR)) {
2005                 u64 bytenr = btrfs_super_log_root(disk_super);
2006
2007                 if (fs_devices->rw_devices == 0) {
2008                         printk(KERN_WARNING "Btrfs log replay required "
2009                                "on RO media\n");
2010                         err = -EIO;
2011                         goto fail_trans_kthread;
2012                 }
2013                 blocksize =
2014                      btrfs_level_size(tree_root,
2015                                       btrfs_super_log_root_level(disk_super));
2016
2017                 log_tree_root = kzalloc(sizeof(struct btrfs_root), GFP_NOFS);
2018                 if (!log_tree_root) {
2019                         err = -ENOMEM;
2020                         goto fail_trans_kthread;
2021                 }
2022
2023                 __setup_root(nodesize, leafsize, sectorsize, stripesize,
2024                              log_tree_root, fs_info, BTRFS_TREE_LOG_OBJECTID);
2025
2026                 log_tree_root->node = read_tree_block(tree_root, bytenr,
2027                                                       blocksize,
2028                                                       generation + 1);
2029                 ret = btrfs_recover_log_trees(log_tree_root);
2030                 BUG_ON(ret);
2031
2032                 if (sb->s_flags & MS_RDONLY) {
2033                         ret =  btrfs_commit_super(tree_root);
2034                         BUG_ON(ret);
2035                 }
2036         }
2037
2038         ret = btrfs_find_orphan_roots(tree_root);
2039         BUG_ON(ret);
2040
2041         if (!(sb->s_flags & MS_RDONLY)) {
2042                 ret = btrfs_cleanup_fs_roots(fs_info);
2043                 BUG_ON(ret);
2044
2045                 ret = btrfs_recover_relocation(tree_root);
2046                 if (ret < 0) {
2047                         printk(KERN_WARNING
2048                                "btrfs: failed to recover relocation\n");
2049                         err = -EINVAL;
2050                         goto fail_trans_kthread;
2051                 }
2052         }
2053
2054         location.objectid = BTRFS_FS_TREE_OBJECTID;
2055         location.type = BTRFS_ROOT_ITEM_KEY;
2056         location.offset = (u64)-1;
2057
2058         fs_info->fs_root = btrfs_read_fs_root_no_name(fs_info, &location);
2059         if (!fs_info->fs_root)
2060                 goto fail_trans_kthread;
2061         if (IS_ERR(fs_info->fs_root)) {
2062                 err = PTR_ERR(fs_info->fs_root);
2063                 goto fail_trans_kthread;
2064         }
2065
2066         if (!(sb->s_flags & MS_RDONLY)) {
2067                 down_read(&fs_info->cleanup_work_sem);
2068                 err = btrfs_orphan_cleanup(fs_info->fs_root);
2069                 if (!err)
2070                         err = btrfs_orphan_cleanup(fs_info->tree_root);
2071                 up_read(&fs_info->cleanup_work_sem);
2072                 if (err) {
2073                         close_ctree(tree_root);
2074                         return ERR_PTR(err);
2075                 }
2076         }
2077
2078         return tree_root;
2079
2080 fail_trans_kthread:
2081         kthread_stop(fs_info->transaction_kthread);
2082 fail_cleaner:
2083         kthread_stop(fs_info->cleaner_kthread);
2084
2085         /*
2086          * make sure we're done with the btree inode before we stop our
2087          * kthreads
2088          */
2089         filemap_write_and_wait(fs_info->btree_inode->i_mapping);
2090         invalidate_inode_pages2(fs_info->btree_inode->i_mapping);
2091
2092 fail_block_groups:
2093         btrfs_free_block_groups(fs_info);
2094         free_extent_buffer(csum_root->node);
2095         free_extent_buffer(csum_root->commit_root);
2096 fail_dev_root:
2097         free_extent_buffer(dev_root->node);
2098         free_extent_buffer(dev_root->commit_root);
2099 fail_extent_root:
2100         free_extent_buffer(extent_root->node);
2101         free_extent_buffer(extent_root->commit_root);
2102 fail_tree_root:
2103         free_extent_buffer(tree_root->node);
2104         free_extent_buffer(tree_root->commit_root);
2105 fail_chunk_root:
2106         free_extent_buffer(chunk_root->node);
2107         free_extent_buffer(chunk_root->commit_root);
2108 fail_sb_buffer:
2109         btrfs_stop_workers(&fs_info->generic_worker);
2110         btrfs_stop_workers(&fs_info->fixup_workers);
2111         btrfs_stop_workers(&fs_info->delalloc_workers);
2112         btrfs_stop_workers(&fs_info->workers);
2113         btrfs_stop_workers(&fs_info->endio_workers);
2114         btrfs_stop_workers(&fs_info->endio_meta_workers);
2115         btrfs_stop_workers(&fs_info->endio_meta_write_workers);
2116         btrfs_stop_workers(&fs_info->endio_write_workers);
2117         btrfs_stop_workers(&fs_info->endio_freespace_worker);
2118         btrfs_stop_workers(&fs_info->submit_workers);
2119         btrfs_stop_workers(&fs_info->delayed_workers);
2120 fail_alloc:
2121         kfree(fs_info->delayed_root);
2122 fail_iput:
2123         invalidate_inode_pages2(fs_info->btree_inode->i_mapping);
2124         iput(fs_info->btree_inode);
2125
2126         btrfs_close_devices(fs_info->fs_devices);
2127         btrfs_mapping_tree_free(&fs_info->mapping_tree);
2128 fail_bdi:
2129         bdi_destroy(&fs_info->bdi);
2130 fail_srcu:
2131         cleanup_srcu_struct(&fs_info->subvol_srcu);
2132 fail:
2133         kfree(extent_root);
2134         kfree(tree_root);
2135         kfree(fs_info);
2136         kfree(chunk_root);
2137         kfree(dev_root);
2138         kfree(csum_root);
2139         return ERR_PTR(err);
2140 }
2141
2142 static void btrfs_end_buffer_write_sync(struct buffer_head *bh, int uptodate)
2143 {
2144         char b[BDEVNAME_SIZE];
2145
2146         if (uptodate) {
2147                 set_buffer_uptodate(bh);
2148         } else {
2149                 printk_ratelimited(KERN_WARNING "lost page write due to "
2150                                         "I/O error on %s\n",
2151                                        bdevname(bh->b_bdev, b));
2152                 /* note, we dont' set_buffer_write_io_error because we have
2153                  * our own ways of dealing with the IO errors
2154                  */
2155                 clear_buffer_uptodate(bh);
2156         }
2157         unlock_buffer(bh);
2158         put_bh(bh);
2159 }
2160
2161 struct buffer_head *btrfs_read_dev_super(struct block_device *bdev)
2162 {
2163         struct buffer_head *bh;
2164         struct buffer_head *latest = NULL;
2165         struct btrfs_super_block *super;
2166         int i;
2167         u64 transid = 0;
2168         u64 bytenr;
2169
2170         /* we would like to check all the supers, but that would make
2171          * a btrfs mount succeed after a mkfs from a different FS.
2172          * So, we need to add a special mount option to scan for
2173          * later supers, using BTRFS_SUPER_MIRROR_MAX instead
2174          */
2175         for (i = 0; i < 1; i++) {
2176                 bytenr = btrfs_sb_offset(i);
2177                 if (bytenr + 4096 >= i_size_read(bdev->bd_inode))
2178                         break;
2179                 bh = __bread(bdev, bytenr / 4096, 4096);
2180                 if (!bh)
2181                         continue;
2182
2183                 super = (struct btrfs_super_block *)bh->b_data;
2184                 if (btrfs_super_bytenr(super) != bytenr ||
2185                     strncmp((char *)(&super->magic), BTRFS_MAGIC,
2186                             sizeof(super->magic))) {
2187                         brelse(bh);
2188                         continue;
2189                 }
2190
2191                 if (!latest || btrfs_super_generation(super) > transid) {
2192                         brelse(latest);
2193                         latest = bh;
2194                         transid = btrfs_super_generation(super);
2195                 } else {
2196                         brelse(bh);
2197                 }
2198         }
2199         return latest;
2200 }
2201
2202 /*
2203  * this should be called twice, once with wait == 0 and
2204  * once with wait == 1.  When wait == 0 is done, all the buffer heads
2205  * we write are pinned.
2206  *
2207  * They are released when wait == 1 is done.
2208  * max_mirrors must be the same for both runs, and it indicates how
2209  * many supers on this one device should be written.
2210  *
2211  * max_mirrors == 0 means to write them all.
2212  */
2213 static int write_dev_supers(struct btrfs_device *device,
2214                             struct btrfs_super_block *sb,
2215                             int do_barriers, int wait, int max_mirrors)
2216 {
2217         struct buffer_head *bh;
2218         int i;
2219         int ret;
2220         int errors = 0;
2221         u32 crc;
2222         u64 bytenr;
2223         int last_barrier = 0;
2224
2225         if (max_mirrors == 0)
2226                 max_mirrors = BTRFS_SUPER_MIRROR_MAX;
2227
2228         /* make sure only the last submit_bh does a barrier */
2229         if (do_barriers) {
2230                 for (i = 0; i < max_mirrors; i++) {
2231                         bytenr = btrfs_sb_offset(i);
2232                         if (bytenr + BTRFS_SUPER_INFO_SIZE >=
2233                             device->total_bytes)
2234                                 break;
2235                         last_barrier = i;
2236                 }
2237         }
2238
2239         for (i = 0; i < max_mirrors; i++) {
2240                 bytenr = btrfs_sb_offset(i);
2241                 if (bytenr + BTRFS_SUPER_INFO_SIZE >= device->total_bytes)
2242                         break;
2243
2244                 if (wait) {
2245                         bh = __find_get_block(device->bdev, bytenr / 4096,
2246                                               BTRFS_SUPER_INFO_SIZE);
2247                         BUG_ON(!bh);
2248                         wait_on_buffer(bh);
2249                         if (!buffer_uptodate(bh))
2250                                 errors++;
2251
2252                         /* drop our reference */
2253                         brelse(bh);
2254
2255                         /* drop the reference from the wait == 0 run */
2256                         brelse(bh);
2257                         continue;
2258                 } else {
2259                         btrfs_set_super_bytenr(sb, bytenr);
2260
2261                         crc = ~(u32)0;
2262                         crc = btrfs_csum_data(NULL, (char *)sb +
2263                                               BTRFS_CSUM_SIZE, crc,
2264                                               BTRFS_SUPER_INFO_SIZE -
2265                                               BTRFS_CSUM_SIZE);
2266                         btrfs_csum_final(crc, sb->csum);
2267
2268                         /*
2269                          * one reference for us, and we leave it for the
2270                          * caller
2271                          */
2272                         bh = __getblk(device->bdev, bytenr / 4096,
2273                                       BTRFS_SUPER_INFO_SIZE);
2274                         memcpy(bh->b_data, sb, BTRFS_SUPER_INFO_SIZE);
2275
2276                         /* one reference for submit_bh */
2277                         get_bh(bh);
2278
2279                         set_buffer_uptodate(bh);
2280                         lock_buffer(bh);
2281                         bh->b_end_io = btrfs_end_buffer_write_sync;
2282                 }
2283
2284                 if (i == last_barrier && do_barriers)
2285                         ret = submit_bh(WRITE_FLUSH_FUA, bh);
2286                 else
2287                         ret = submit_bh(WRITE_SYNC, bh);
2288
2289                 if (ret)
2290                         errors++;
2291         }
2292         return errors < i ? 0 : -1;
2293 }
2294
2295 int write_all_supers(struct btrfs_root *root, int max_mirrors)
2296 {
2297         struct list_head *head;
2298         struct btrfs_device *dev;
2299         struct btrfs_super_block *sb;
2300         struct btrfs_dev_item *dev_item;
2301         int ret;
2302         int do_barriers;
2303         int max_errors;
2304         int total_errors = 0;
2305         u64 flags;
2306
2307         max_errors = btrfs_super_num_devices(&root->fs_info->super_copy) - 1;
2308         do_barriers = !btrfs_test_opt(root, NOBARRIER);
2309
2310         sb = &root->fs_info->super_for_commit;
2311         dev_item = &sb->dev_item;
2312
2313         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
2314         head = &root->fs_info->fs_devices->devices;
2315         list_for_each_entry_rcu(dev, head, dev_list) {
2316                 if (!dev->bdev) {
2317                         total_errors++;
2318                         continue;
2319                 }
2320                 if (!dev->in_fs_metadata || !dev->writeable)
2321                         continue;
2322
2323                 btrfs_set_stack_device_generation(dev_item, 0);
2324                 btrfs_set_stack_device_type(dev_item, dev->type);
2325                 btrfs_set_stack_device_id(dev_item, dev->devid);
2326                 btrfs_set_stack_device_total_bytes(dev_item, dev->total_bytes);
2327                 btrfs_set_stack_device_bytes_used(dev_item, dev->bytes_used);
2328                 btrfs_set_stack_device_io_align(dev_item, dev->io_align);
2329                 btrfs_set_stack_device_io_width(dev_item, dev->io_width);
2330                 btrfs_set_stack_device_sector_size(dev_item, dev->sector_size);
2331                 memcpy(dev_item->uuid, dev->uuid, BTRFS_UUID_SIZE);
2332                 memcpy(dev_item->fsid, dev->fs_devices->fsid, BTRFS_UUID_SIZE);
2333
2334                 flags = btrfs_super_flags(sb);
2335                 btrfs_set_super_flags(sb, flags | BTRFS_HEADER_FLAG_WRITTEN);
2336
2337                 ret = write_dev_supers(dev, sb, do_barriers, 0, max_mirrors);
2338                 if (ret)
2339                         total_errors++;
2340         }
2341         if (total_errors > max_errors) {
2342                 printk(KERN_ERR "btrfs: %d errors while writing supers\n",
2343                        total_errors);
2344                 BUG();
2345         }
2346
2347         total_errors = 0;
2348         list_for_each_entry_rcu(dev, head, dev_list) {
2349                 if (!dev->bdev)
2350                         continue;
2351                 if (!dev->in_fs_metadata || !dev->writeable)
2352                         continue;
2353
2354                 ret = write_dev_supers(dev, sb, do_barriers, 1, max_mirrors);
2355                 if (ret)
2356                         total_errors++;
2357         }
2358         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
2359         if (total_errors > max_errors) {
2360                 printk(KERN_ERR "btrfs: %d errors while writing supers\n",
2361                        total_errors);
2362                 BUG();
2363         }
2364         return 0;
2365 }
2366
2367 int write_ctree_super(struct btrfs_trans_handle *trans,
2368                       struct btrfs_root *root, int max_mirrors)
2369 {
2370         int ret;
2371
2372         ret = write_all_supers(root, max_mirrors);
2373         return ret;
2374 }
2375
2376 int btrfs_free_fs_root(struct btrfs_fs_info *fs_info, struct btrfs_root *root)
2377 {
2378         spin_lock(&fs_info->fs_roots_radix_lock);
2379         radix_tree_delete(&fs_info->fs_roots_radix,
2380                           (unsigned long)root->root_key.objectid);
2381         spin_unlock(&fs_info->fs_roots_radix_lock);
2382
2383         if (btrfs_root_refs(&root->root_item) == 0)
2384                 synchronize_srcu(&fs_info->subvol_srcu);
2385
2386         __btrfs_remove_free_space_cache(root->free_ino_pinned);
2387         __btrfs_remove_free_space_cache(root->free_ino_ctl);
2388         free_fs_root(root);
2389         return 0;
2390 }
2391
2392 static void free_fs_root(struct btrfs_root *root)
2393 {
2394         iput(root->cache_inode);
2395         WARN_ON(!RB_EMPTY_ROOT(&root->inode_tree));
2396         if (root->anon_super.s_dev) {
2397                 down_write(&root->anon_super.s_umount);
2398                 kill_anon_super(&root->anon_super);
2399         }
2400         free_extent_buffer(root->node);
2401         free_extent_buffer(root->commit_root);
2402         kfree(root->free_ino_ctl);
2403         kfree(root->free_ino_pinned);
2404         kfree(root->name);
2405         kfree(root);
2406 }
2407
2408 static int del_fs_roots(struct btrfs_fs_info *fs_info)
2409 {
2410         int ret;
2411         struct btrfs_root *gang[8];
2412         int i;
2413
2414         while (!list_empty(&fs_info->dead_roots)) {
2415                 gang[0] = list_entry(fs_info->dead_roots.next,
2416                                      struct btrfs_root, root_list);
2417                 list_del(&gang[0]->root_list);
2418
2419                 if (gang[0]->in_radix) {
2420                         btrfs_free_fs_root(fs_info, gang[0]);
2421                 } else {
2422                         free_extent_buffer(gang[0]->node);
2423                         free_extent_buffer(gang[0]->commit_root);
2424                         kfree(gang[0]);
2425                 }
2426         }
2427
2428         while (1) {
2429                 ret = radix_tree_gang_lookup(&fs_info->fs_roots_radix,
2430                                              (void **)gang, 0,
2431                                              ARRAY_SIZE(gang));
2432                 if (!ret)
2433                         break;
2434                 for (i = 0; i < ret; i++)
2435                         btrfs_free_fs_root(fs_info, gang[i]);
2436         }
2437         return 0;
2438 }
2439
2440 int btrfs_cleanup_fs_roots(struct btrfs_fs_info *fs_info)
2441 {
2442         u64 root_objectid = 0;
2443         struct btrfs_root *gang[8];
2444         int i;
2445         int ret;
2446
2447         while (1) {
2448                 ret = radix_tree_gang_lookup(&fs_info->fs_roots_radix,
2449                                              (void **)gang, root_objectid,
2450                                              ARRAY_SIZE(gang));
2451                 if (!ret)
2452                         break;
2453
2454                 root_objectid = gang[ret - 1]->root_key.objectid + 1;
2455                 for (i = 0; i < ret; i++) {
2456                         int err;
2457
2458                         root_objectid = gang[i]->root_key.objectid;
2459                         err = btrfs_orphan_cleanup(gang[i]);
2460                         if (err)
2461                                 return err;
2462                 }
2463                 root_objectid++;
2464         }
2465         return 0;
2466 }
2467
2468 int btrfs_commit_super(struct btrfs_root *root)
2469 {
2470         struct btrfs_trans_handle *trans;
2471         int ret;
2472
2473         mutex_lock(&root->fs_info->cleaner_mutex);
2474         btrfs_run_delayed_iputs(root);
2475         btrfs_clean_old_snapshots(root);
2476         mutex_unlock(&root->fs_info->cleaner_mutex);
2477
2478         /* wait until ongoing cleanup work done */
2479         down_write(&root->fs_info->cleanup_work_sem);
2480         up_write(&root->fs_info->cleanup_work_sem);
2481
2482         trans = btrfs_join_transaction(root);
2483         if (IS_ERR(trans))
2484                 return PTR_ERR(trans);
2485         ret = btrfs_commit_transaction(trans, root);
2486         BUG_ON(ret);
2487         /* run commit again to drop the original snapshot */
2488         trans = btrfs_join_transaction(root);
2489         if (IS_ERR(trans))
2490                 return PTR_ERR(trans);
2491         btrfs_commit_transaction(trans, root);
2492         ret = btrfs_write_and_wait_transaction(NULL, root);
2493         BUG_ON(ret);
2494
2495         ret = write_ctree_super(NULL, root, 0);
2496         return ret;
2497 }
2498
2499 int close_ctree(struct btrfs_root *root)
2500 {
2501         struct btrfs_fs_info *fs_info = root->fs_info;
2502         int ret;
2503
2504         fs_info->closing = 1;
2505         smp_mb();
2506
2507         btrfs_scrub_cancel(root);
2508
2509         /* wait for any defraggers to finish */
2510         wait_event(fs_info->transaction_wait,
2511                    (atomic_read(&fs_info->defrag_running) == 0));
2512
2513         /* clear out the rbtree of defraggable inodes */
2514         btrfs_run_defrag_inodes(root->fs_info);
2515
2516         btrfs_put_block_group_cache(fs_info);
2517
2518         /*
2519          * Here come 2 situations when btrfs is broken to flip readonly:
2520          *
2521          * 1. when btrfs flips readonly somewhere else before
2522          * btrfs_commit_super, sb->s_flags has MS_RDONLY flag,
2523          * and btrfs will skip to write sb directly to keep
2524          * ERROR state on disk.
2525          *
2526          * 2. when btrfs flips readonly just in btrfs_commit_super,
2527          * and in such case, btrfs cannot write sb via btrfs_commit_super,
2528          * and since fs_state has been set BTRFS_SUPER_FLAG_ERROR flag,
2529          * btrfs will cleanup all FS resources first and write sb then.
2530          */
2531         if (!(fs_info->sb->s_flags & MS_RDONLY)) {
2532                 ret = btrfs_commit_super(root);
2533                 if (ret)
2534                         printk(KERN_ERR "btrfs: commit super ret %d\n", ret);
2535         }
2536
2537         if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
2538                 ret = btrfs_error_commit_super(root);
2539                 if (ret)
2540                         printk(KERN_ERR "btrfs: commit super ret %d\n", ret);
2541         }
2542
2543         kthread_stop(root->fs_info->transaction_kthread);
2544         kthread_stop(root->fs_info->cleaner_kthread);
2545
2546         fs_info->closing = 2;
2547         smp_mb();
2548
2549         if (fs_info->delalloc_bytes) {
2550                 printk(KERN_INFO "btrfs: at unmount delalloc count %llu\n",
2551                        (unsigned long long)fs_info->delalloc_bytes);
2552         }
2553         if (fs_info->total_ref_cache_size) {
2554                 printk(KERN_INFO "btrfs: at umount reference cache size %llu\n",
2555                        (unsigned long long)fs_info->total_ref_cache_size);
2556         }
2557
2558         free_extent_buffer(fs_info->extent_root->node);
2559         free_extent_buffer(fs_info->extent_root->commit_root);
2560         free_extent_buffer(fs_info->tree_root->node);
2561         free_extent_buffer(fs_info->tree_root->commit_root);
2562         free_extent_buffer(root->fs_info->chunk_root->node);
2563         free_extent_buffer(root->fs_info->chunk_root->commit_root);
2564         free_extent_buffer(root->fs_info->dev_root->node);
2565         free_extent_buffer(root->fs_info->dev_root->commit_root);
2566         free_extent_buffer(root->fs_info->csum_root->node);
2567         free_extent_buffer(root->fs_info->csum_root->commit_root);
2568
2569         btrfs_free_block_groups(root->fs_info);
2570
2571         del_fs_roots(fs_info);
2572
2573         iput(fs_info->btree_inode);
2574         kfree(fs_info->delayed_root);
2575
2576         btrfs_stop_workers(&fs_info->generic_worker);
2577         btrfs_stop_workers(&fs_info->fixup_workers);
2578         btrfs_stop_workers(&fs_info->delalloc_workers);
2579         btrfs_stop_workers(&fs_info->workers);
2580         btrfs_stop_workers(&fs_info->endio_workers);
2581         btrfs_stop_workers(&fs_info->endio_meta_workers);
2582         btrfs_stop_workers(&fs_info->endio_meta_write_workers);
2583         btrfs_stop_workers(&fs_info->endio_write_workers);
2584         btrfs_stop_workers(&fs_info->endio_freespace_worker);
2585         btrfs_stop_workers(&fs_info->submit_workers);
2586         btrfs_stop_workers(&fs_info->delayed_workers);
2587
2588         btrfs_close_devices(fs_info->fs_devices);
2589         btrfs_mapping_tree_free(&fs_info->mapping_tree);
2590
2591         bdi_destroy(&fs_info->bdi);
2592         cleanup_srcu_struct(&fs_info->subvol_srcu);
2593
2594         kfree(fs_info->extent_root);
2595         kfree(fs_info->tree_root);
2596         kfree(fs_info->chunk_root);
2597         kfree(fs_info->dev_root);
2598         kfree(fs_info->csum_root);
2599         kfree(fs_info);
2600
2601         return 0;
2602 }
2603
2604 int btrfs_buffer_uptodate(struct extent_buffer *buf, u64 parent_transid)
2605 {
2606         int ret;
2607         struct inode *btree_inode = buf->first_page->mapping->host;
2608
2609         ret = extent_buffer_uptodate(&BTRFS_I(btree_inode)->io_tree, buf,
2610                                      NULL);
2611         if (!ret)
2612                 return ret;
2613
2614         ret = verify_parent_transid(&BTRFS_I(btree_inode)->io_tree, buf,
2615                                     parent_transid);
2616         return !ret;
2617 }
2618
2619 int btrfs_set_buffer_uptodate(struct extent_buffer *buf)
2620 {
2621         struct inode *btree_inode = buf->first_page->mapping->host;
2622         return set_extent_buffer_uptodate(&BTRFS_I(btree_inode)->io_tree,
2623                                           buf);
2624 }
2625
2626 void btrfs_mark_buffer_dirty(struct extent_buffer *buf)
2627 {
2628         struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
2629         u64 transid = btrfs_header_generation(buf);
2630         struct inode *btree_inode = root->fs_info->btree_inode;
2631         int was_dirty;
2632
2633         btrfs_assert_tree_locked(buf);
2634         if (transid != root->fs_info->generation) {
2635                 printk(KERN_CRIT "btrfs transid mismatch buffer %llu, "
2636                        "found %llu running %llu\n",
2637                         (unsigned long long)buf->start,
2638                         (unsigned long long)transid,
2639                         (unsigned long long)root->fs_info->generation);
2640                 WARN_ON(1);
2641         }
2642         was_dirty = set_extent_buffer_dirty(&BTRFS_I(btree_inode)->io_tree,
2643                                             buf);
2644         if (!was_dirty) {
2645                 spin_lock(&root->fs_info->delalloc_lock);
2646                 root->fs_info->dirty_metadata_bytes += buf->len;
2647                 spin_unlock(&root->fs_info->delalloc_lock);
2648         }
2649 }
2650
2651 void btrfs_btree_balance_dirty(struct btrfs_root *root, unsigned long nr)
2652 {
2653         /*
2654          * looks as though older kernels can get into trouble with
2655          * this code, they end up stuck in balance_dirty_pages forever
2656          */
2657         u64 num_dirty;
2658         unsigned long thresh = 32 * 1024 * 1024;
2659
2660         if (current->flags & PF_MEMALLOC)
2661                 return;
2662
2663         btrfs_balance_delayed_items(root);
2664
2665         num_dirty = root->fs_info->dirty_metadata_bytes;
2666
2667         if (num_dirty > thresh) {
2668                 balance_dirty_pages_ratelimited_nr(
2669                                    root->fs_info->btree_inode->i_mapping, 1);
2670         }
2671         return;
2672 }
2673
2674 void __btrfs_btree_balance_dirty(struct btrfs_root *root, unsigned long nr)
2675 {
2676         /*
2677          * looks as though older kernels can get into trouble with
2678          * this code, they end up stuck in balance_dirty_pages forever
2679          */
2680         u64 num_dirty;
2681         unsigned long thresh = 32 * 1024 * 1024;
2682
2683         if (current->flags & PF_MEMALLOC)
2684                 return;
2685
2686         num_dirty = root->fs_info->dirty_metadata_bytes;
2687
2688         if (num_dirty > thresh) {
2689                 balance_dirty_pages_ratelimited_nr(
2690                                    root->fs_info->btree_inode->i_mapping, 1);
2691         }
2692         return;
2693 }
2694
2695 int btrfs_read_buffer(struct extent_buffer *buf, u64 parent_transid)
2696 {
2697         struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
2698         int ret;
2699         ret = btree_read_extent_buffer_pages(root, buf, 0, parent_transid);
2700         if (ret == 0)
2701                 set_bit(EXTENT_BUFFER_UPTODATE, &buf->bflags);
2702         return ret;
2703 }
2704
2705 int btree_lock_page_hook(struct page *page)
2706 {
2707         struct inode *inode = page->mapping->host;
2708         struct btrfs_root *root = BTRFS_I(inode)->root;
2709         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
2710         struct extent_buffer *eb;
2711         unsigned long len;
2712         u64 bytenr = page_offset(page);
2713
2714         if (page->private == EXTENT_PAGE_PRIVATE)
2715                 goto out;
2716
2717         len = page->private >> 2;
2718         eb = find_extent_buffer(io_tree, bytenr, len);
2719         if (!eb)
2720                 goto out;
2721
2722         btrfs_tree_lock(eb);
2723         btrfs_set_header_flag(eb, BTRFS_HEADER_FLAG_WRITTEN);
2724
2725         if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) {
2726                 spin_lock(&root->fs_info->delalloc_lock);
2727                 if (root->fs_info->dirty_metadata_bytes >= eb->len)
2728                         root->fs_info->dirty_metadata_bytes -= eb->len;
2729                 else
2730                         WARN_ON(1);
2731                 spin_unlock(&root->fs_info->delalloc_lock);
2732         }
2733
2734         btrfs_tree_unlock(eb);
2735         free_extent_buffer(eb);
2736 out:
2737         lock_page(page);
2738         return 0;
2739 }
2740
2741 static void btrfs_check_super_valid(struct btrfs_fs_info *fs_info,
2742                               int read_only)
2743 {
2744         if (read_only)
2745                 return;
2746
2747         if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR)
2748                 printk(KERN_WARNING "warning: mount fs with errors, "
2749                        "running btrfsck is recommended\n");
2750 }
2751
2752 int btrfs_error_commit_super(struct btrfs_root *root)
2753 {
2754         int ret;
2755
2756         mutex_lock(&root->fs_info->cleaner_mutex);
2757         btrfs_run_delayed_iputs(root);
2758         mutex_unlock(&root->fs_info->cleaner_mutex);
2759
2760         down_write(&root->fs_info->cleanup_work_sem);
2761         up_write(&root->fs_info->cleanup_work_sem);
2762
2763         /* cleanup FS via transaction */
2764         btrfs_cleanup_transaction(root);
2765
2766         ret = write_ctree_super(NULL, root, 0);
2767
2768         return ret;
2769 }
2770
2771 static int btrfs_destroy_ordered_operations(struct btrfs_root *root)
2772 {
2773         struct btrfs_inode *btrfs_inode;
2774         struct list_head splice;
2775
2776         INIT_LIST_HEAD(&splice);
2777
2778         mutex_lock(&root->fs_info->ordered_operations_mutex);
2779         spin_lock(&root->fs_info->ordered_extent_lock);
2780
2781         list_splice_init(&root->fs_info->ordered_operations, &splice);
2782         while (!list_empty(&splice)) {
2783                 btrfs_inode = list_entry(splice.next, struct btrfs_inode,
2784                                          ordered_operations);
2785
2786                 list_del_init(&btrfs_inode->ordered_operations);
2787
2788                 btrfs_invalidate_inodes(btrfs_inode->root);
2789         }
2790
2791         spin_unlock(&root->fs_info->ordered_extent_lock);
2792         mutex_unlock(&root->fs_info->ordered_operations_mutex);
2793
2794         return 0;
2795 }
2796
2797 static int btrfs_destroy_ordered_extents(struct btrfs_root *root)
2798 {
2799         struct list_head splice;
2800         struct btrfs_ordered_extent *ordered;
2801         struct inode *inode;
2802
2803         INIT_LIST_HEAD(&splice);
2804
2805         spin_lock(&root->fs_info->ordered_extent_lock);
2806
2807         list_splice_init(&root->fs_info->ordered_extents, &splice);
2808         while (!list_empty(&splice)) {
2809                 ordered = list_entry(splice.next, struct btrfs_ordered_extent,
2810                                      root_extent_list);
2811
2812                 list_del_init(&ordered->root_extent_list);
2813                 atomic_inc(&ordered->refs);
2814
2815                 /* the inode may be getting freed (in sys_unlink path). */
2816                 inode = igrab(ordered->inode);
2817
2818                 spin_unlock(&root->fs_info->ordered_extent_lock);
2819                 if (inode)
2820                         iput(inode);
2821
2822                 atomic_set(&ordered->refs, 1);
2823                 btrfs_put_ordered_extent(ordered);
2824
2825                 spin_lock(&root->fs_info->ordered_extent_lock);
2826         }
2827
2828         spin_unlock(&root->fs_info->ordered_extent_lock);
2829
2830         return 0;
2831 }
2832
2833 static int btrfs_destroy_delayed_refs(struct btrfs_transaction *trans,
2834                                       struct btrfs_root *root)
2835 {
2836         struct rb_node *node;
2837         struct btrfs_delayed_ref_root *delayed_refs;
2838         struct btrfs_delayed_ref_node *ref;
2839         int ret = 0;
2840
2841         delayed_refs = &trans->delayed_refs;
2842
2843         spin_lock(&delayed_refs->lock);
2844         if (delayed_refs->num_entries == 0) {
2845                 spin_unlock(&delayed_refs->lock);
2846                 printk(KERN_INFO "delayed_refs has NO entry\n");
2847                 return ret;
2848         }
2849
2850         node = rb_first(&delayed_refs->root);
2851         while (node) {
2852                 ref = rb_entry(node, struct btrfs_delayed_ref_node, rb_node);
2853                 node = rb_next(node);
2854
2855                 ref->in_tree = 0;
2856                 rb_erase(&ref->rb_node, &delayed_refs->root);
2857                 delayed_refs->num_entries--;
2858
2859                 atomic_set(&ref->refs, 1);
2860                 if (btrfs_delayed_ref_is_head(ref)) {
2861                         struct btrfs_delayed_ref_head *head;
2862
2863                         head = btrfs_delayed_node_to_head(ref);
2864                         mutex_lock(&head->mutex);
2865                         kfree(head->extent_op);
2866                         delayed_refs->num_heads--;
2867                         if (list_empty(&head->cluster))
2868                                 delayed_refs->num_heads_ready--;
2869                         list_del_init(&head->cluster);
2870                         mutex_unlock(&head->mutex);
2871                 }
2872
2873                 spin_unlock(&delayed_refs->lock);
2874                 btrfs_put_delayed_ref(ref);
2875
2876                 cond_resched();
2877                 spin_lock(&delayed_refs->lock);
2878         }
2879
2880         spin_unlock(&delayed_refs->lock);
2881
2882         return ret;
2883 }
2884
2885 static int btrfs_destroy_pending_snapshots(struct btrfs_transaction *t)
2886 {
2887         struct btrfs_pending_snapshot *snapshot;
2888         struct list_head splice;
2889
2890         INIT_LIST_HEAD(&splice);
2891
2892         list_splice_init(&t->pending_snapshots, &splice);
2893
2894         while (!list_empty(&splice)) {
2895                 snapshot = list_entry(splice.next,
2896                                       struct btrfs_pending_snapshot,
2897                                       list);
2898
2899                 list_del_init(&snapshot->list);
2900
2901                 kfree(snapshot);
2902         }
2903
2904         return 0;
2905 }
2906
2907 static int btrfs_destroy_delalloc_inodes(struct btrfs_root *root)
2908 {
2909         struct btrfs_inode *btrfs_inode;
2910         struct list_head splice;
2911
2912         INIT_LIST_HEAD(&splice);
2913
2914         spin_lock(&root->fs_info->delalloc_lock);
2915         list_splice_init(&root->fs_info->delalloc_inodes, &splice);
2916
2917         while (!list_empty(&splice)) {
2918                 btrfs_inode = list_entry(splice.next, struct btrfs_inode,
2919                                     delalloc_inodes);
2920
2921                 list_del_init(&btrfs_inode->delalloc_inodes);
2922
2923                 btrfs_invalidate_inodes(btrfs_inode->root);
2924         }
2925
2926         spin_unlock(&root->fs_info->delalloc_lock);
2927
2928         return 0;
2929 }
2930
2931 static int btrfs_destroy_marked_extents(struct btrfs_root *root,
2932                                         struct extent_io_tree *dirty_pages,
2933                                         int mark)
2934 {
2935         int ret;
2936         struct page *page;
2937         struct inode *btree_inode = root->fs_info->btree_inode;
2938         struct extent_buffer *eb;
2939         u64 start = 0;
2940         u64 end;
2941         u64 offset;
2942         unsigned long index;
2943
2944         while (1) {
2945                 ret = find_first_extent_bit(dirty_pages, start, &start, &end,
2946                                             mark);
2947                 if (ret)
2948                         break;
2949
2950                 clear_extent_bits(dirty_pages, start, end, mark, GFP_NOFS);
2951                 while (start <= end) {
2952                         index = start >> PAGE_CACHE_SHIFT;
2953                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
2954                         page = find_get_page(btree_inode->i_mapping, index);
2955                         if (!page)
2956                                 continue;
2957                         offset = page_offset(page);
2958
2959                         spin_lock(&dirty_pages->buffer_lock);
2960                         eb = radix_tree_lookup(
2961                              &(&BTRFS_I(page->mapping->host)->io_tree)->buffer,
2962                                                offset >> PAGE_CACHE_SHIFT);
2963                         spin_unlock(&dirty_pages->buffer_lock);
2964                         if (eb) {
2965                                 ret = test_and_clear_bit(EXTENT_BUFFER_DIRTY,
2966                                                          &eb->bflags);
2967                                 atomic_set(&eb->refs, 1);
2968                         }
2969                         if (PageWriteback(page))
2970                                 end_page_writeback(page);
2971
2972                         lock_page(page);
2973                         if (PageDirty(page)) {
2974                                 clear_page_dirty_for_io(page);
2975                                 spin_lock_irq(&page->mapping->tree_lock);
2976                                 radix_tree_tag_clear(&page->mapping->page_tree,
2977                                                         page_index(page),
2978                                                         PAGECACHE_TAG_DIRTY);
2979                                 spin_unlock_irq(&page->mapping->tree_lock);
2980                         }
2981
2982                         page->mapping->a_ops->invalidatepage(page, 0);
2983                         unlock_page(page);
2984                 }
2985         }
2986
2987         return ret;
2988 }
2989
2990 static int btrfs_destroy_pinned_extent(struct btrfs_root *root,
2991                                        struct extent_io_tree *pinned_extents)
2992 {
2993         struct extent_io_tree *unpin;
2994         u64 start;
2995         u64 end;
2996         int ret;
2997
2998         unpin = pinned_extents;
2999         while (1) {
3000                 ret = find_first_extent_bit(unpin, 0, &start, &end,
3001                                             EXTENT_DIRTY);
3002                 if (ret)
3003                         break;
3004
3005                 /* opt_discard */
3006                 if (btrfs_test_opt(root, DISCARD))
3007                         ret = btrfs_error_discard_extent(root, start,
3008                                                          end + 1 - start,
3009                                                          NULL);
3010
3011                 clear_extent_dirty(unpin, start, end, GFP_NOFS);
3012                 btrfs_error_unpin_extent_range(root, start, end);
3013                 cond_resched();
3014         }
3015
3016         return 0;
3017 }
3018
3019 static int btrfs_cleanup_transaction(struct btrfs_root *root)
3020 {
3021         struct btrfs_transaction *t;
3022         LIST_HEAD(list);
3023
3024         WARN_ON(1);
3025
3026         mutex_lock(&root->fs_info->transaction_kthread_mutex);
3027
3028         spin_lock(&root->fs_info->trans_lock);
3029         list_splice_init(&root->fs_info->trans_list, &list);
3030         root->fs_info->trans_no_join = 1;
3031         spin_unlock(&root->fs_info->trans_lock);
3032
3033         while (!list_empty(&list)) {
3034                 t = list_entry(list.next, struct btrfs_transaction, list);
3035                 if (!t)
3036                         break;
3037
3038                 btrfs_destroy_ordered_operations(root);
3039
3040                 btrfs_destroy_ordered_extents(root);
3041
3042                 btrfs_destroy_delayed_refs(t, root);
3043
3044                 btrfs_block_rsv_release(root,
3045                                         &root->fs_info->trans_block_rsv,
3046                                         t->dirty_pages.dirty_bytes);
3047
3048                 /* FIXME: cleanup wait for commit */
3049                 t->in_commit = 1;
3050                 t->blocked = 1;
3051                 if (waitqueue_active(&root->fs_info->transaction_blocked_wait))
3052                         wake_up(&root->fs_info->transaction_blocked_wait);
3053
3054                 t->blocked = 0;
3055                 if (waitqueue_active(&root->fs_info->transaction_wait))
3056                         wake_up(&root->fs_info->transaction_wait);
3057
3058                 t->commit_done = 1;
3059                 if (waitqueue_active(&t->commit_wait))
3060                         wake_up(&t->commit_wait);
3061
3062                 btrfs_destroy_pending_snapshots(t);
3063
3064                 btrfs_destroy_delalloc_inodes(root);
3065
3066                 spin_lock(&root->fs_info->trans_lock);
3067                 root->fs_info->running_transaction = NULL;
3068                 spin_unlock(&root->fs_info->trans_lock);
3069
3070                 btrfs_destroy_marked_extents(root, &t->dirty_pages,
3071                                              EXTENT_DIRTY);
3072
3073                 btrfs_destroy_pinned_extent(root,
3074                                             root->fs_info->pinned_extents);
3075
3076                 atomic_set(&t->use_count, 0);
3077                 list_del_init(&t->list);
3078                 memset(t, 0, sizeof(*t));
3079                 kmem_cache_free(btrfs_transaction_cachep, t);
3080         }
3081
3082         spin_lock(&root->fs_info->trans_lock);
3083         root->fs_info->trans_no_join = 0;
3084         spin_unlock(&root->fs_info->trans_lock);
3085         mutex_unlock(&root->fs_info->transaction_kthread_mutex);
3086
3087         return 0;
3088 }
3089
3090 static struct extent_io_ops btree_extent_io_ops = {
3091         .write_cache_pages_lock_hook = btree_lock_page_hook,
3092         .readpage_end_io_hook = btree_readpage_end_io_hook,
3093         .submit_bio_hook = btree_submit_bio_hook,
3094         /* note we're sharing with inode.c for the merge bio hook */
3095         .merge_bio_hook = btrfs_merge_bio_hook,
3096 };