fs/btrfs/ordered-data.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/slab.h>
  20 #include <linux/blkdev.h>
  21 #include <linux/writeback.h>
  22 #include <linux/pagevec.h>
  23 #include "ctree.h"
  24 #include "transaction.h"
  25 #include "btrfs_inode.h"
  26 #include "extent_io.h"
  27
  28 static u64 entry_end(struct btrfs_ordered_extent *entry)
  29 {
  30         if (entry->file_offset + entry->len < entry->file_offset)
  31                 return (u64)-1;
  32         return entry->file_offset + entry->len;
  33 }
  34
  35 /* returns NULL if the insertion worked, or it returns the node it did find
  36  * in the tree
  37  */
  38 static struct rb_node *tree_insert(struct rb_root *root, u64 file_offset,
  39                                    struct rb_node *node)
  40 {
  41         struct rb_node **p = &root->rb_node;
  42         struct rb_node *parent = NULL;
  43         struct btrfs_ordered_extent *entry;
  44
  45         while (*p) {
  46                 parent = *p;
  47                 entry = rb_entry(parent, struct btrfs_ordered_extent, rb_node);
  48
  49                 if (file_offset < entry->file_offset)
  50                         p = &(*p)->rb_left;
  51                 else if (file_offset >= entry_end(entry))
  52                         p = &(*p)->rb_right;
  53                 else
  54                         return parent;
  55         }
  56
  57         rb_link_node(node, parent, p);
  58         rb_insert_color(node, root);
  59         return NULL;
  60 }
  61
  62 /*
  63  * look for a given offset in the tree, and if it can't be found return the
  64  * first lesser offset
  65  */
  66 static struct rb_node *__tree_search(struct rb_root *root, u64 file_offset,
  67                                      struct rb_node **prev_ret)
  68 {
  69         struct rb_node *n = root->rb_node;
  70         struct rb_node *prev = NULL;
  71         struct rb_node *test;
  72         struct btrfs_ordered_extent *entry;
  73         struct btrfs_ordered_extent *prev_entry = NULL;
  74
  75         while (n) {
  76                 entry = rb_entry(n, struct btrfs_ordered_extent, rb_node);
  77                 prev = n;
  78                 prev_entry = entry;
  79
  80                 if (file_offset < entry->file_offset)
  81                         n = n->rb_left;
  82                 else if (file_offset >= entry_end(entry))
  83                         n = n->rb_right;
  84                 else
  85                         return n;
  86         }
  87         if (!prev_ret)
  88                 return NULL;
  89
  90         while (prev && file_offset >= entry_end(prev_entry)) {
  91                 test = rb_next(prev);
  92                 if (!test)
  93                         break;
  94                 prev_entry = rb_entry(test, struct btrfs_ordered_extent,
  95                                       rb_node);
  96                 if (file_offset < entry_end(prev_entry))
  97                         break;
  98
  99                 prev = test;
 100         }
 101         if (prev)
 102                 prev_entry = rb_entry(prev, struct btrfs_ordered_extent,
 103                                       rb_node);
 104         while (prev && file_offset < entry_end(prev_entry)) {
 105                 test = rb_prev(prev);
 106                 if (!test)
 107                         break;
 108                 prev_entry = rb_entry(test, struct btrfs_ordered_extent,
 109                                       rb_node);
 110                 prev = test;
 111         }
 112         *prev_ret = prev;
 113         return NULL;
 114 }
 115
 116 /*
 117  * helper to check if a given offset is inside a given entry
 118  */
 119 static int offset_in_entry(struct btrfs_ordered_extent *entry, u64 file_offset)
 120 {
 121         if (file_offset < entry->file_offset ||
 122             entry->file_offset + entry->len <= file_offset)
 123                 return 0;
 124         return 1;
 125 }
 126
 127 static int range_overlaps(struct btrfs_ordered_extent *entry, u64 file_offset,
 128                           u64 len)
 129 {
 130         if (file_offset + len <= entry->file_offset ||
 131             entry->file_offset + entry->len <= file_offset)
 132                 return 0;
 133         return 1;
 134 }
 135
 136 /*
 137  * look find the first ordered struct that has this offset, otherwise
 138  * the first one less than this offset
 139  */
 140 static inline struct rb_node *tree_search(struct btrfs_ordered_inode_tree *tree,
 141                                           u64 file_offset)
 142 {
 143         struct rb_root *root = &tree->tree;
 144         struct rb_node *prev;
 145         struct rb_node *ret;
 146         struct btrfs_ordered_extent *entry;
 147
 148         if (tree->last) {
 149                 entry = rb_entry(tree->last, struct btrfs_ordered_extent,
 150                                  rb_node);
 151                 if (offset_in_entry(entry, file_offset))
 152                         return tree->last;
 153         }
 154         ret = __tree_search(root, file_offset, &prev);
 155         if (!ret)
 156                 ret = prev;
 157         if (ret)
 158                 tree->last = ret;
 159         return ret;
 160 }
 161
 162 /* allocate and add a new ordered_extent into the per-inode tree.
 163  * file_offset is the logical offset in the file
 164  *
 165  * start is the disk block number of an extent already reserved in the
 166  * extent allocation tree
 167  *
 168  * len is the length of the extent
 169  *
 170  * The tree is given a single reference on the ordered extent that was
 171  * inserted.
 172  */
 173 static int __btrfs_add_ordered_extent(struct inode *inode, u64 file_offset,
 174                                       u64 start, u64 len, u64 disk_len,
 175                                       int type, int dio)
 176 {
 177         struct btrfs_ordered_inode_tree *tree;
 178         struct rb_node *node;
 179         struct btrfs_ordered_extent *entry;
 180
 181         tree = &BTRFS_I(inode)->ordered_tree;
 182         entry = kzalloc(sizeof(*entry), GFP_NOFS);
 183         if (!entry)
 184                 return -ENOMEM;
 185
 186         entry->file_offset = file_offset;
 187         entry->start = start;
 188         entry->len = len;
 189         entry->disk_len = disk_len;
 190         entry->bytes_left = len;
 191         entry->inode = inode;
 192         if (type != BTRFS_ORDERED_IO_DONE && type != BTRFS_ORDERED_COMPLETE)
 193                 set_bit(type, &entry->flags);
 194
 195         if (dio)
 196                 set_bit(BTRFS_ORDERED_DIRECT, &entry->flags);
 197
 198         /* one ref for the tree */
 199         atomic_set(&entry->refs, 1);
 200         init_waitqueue_head(&entry->wait);
 201         INIT_LIST_HEAD(&entry->list);
 202         INIT_LIST_HEAD(&entry->root_extent_list);
 203
 204         spin_lock(&tree->lock);
 205         node = tree_insert(&tree->tree, file_offset,
 206                            &entry->rb_node);
 207         BUG_ON(node);
 208         spin_unlock(&tree->lock);
 209
 210         spin_lock(&BTRFS_I(inode)->root->fs_info->ordered_extent_lock);
 211         list_add_tail(&entry->root_extent_list,
 212                       &BTRFS_I(inode)->root->fs_info->ordered_extents);
 213         spin_unlock(&BTRFS_I(inode)->root->fs_info->ordered_extent_lock);
 214
 215         BUG_ON(node);
 216         return 0;
 217 }
 218
 219 int btrfs_add_ordered_extent(struct inode *inode, u64 file_offset,
 220                              u64 start, u64 len, u64 disk_len, int type)
 221 {
 222         return __btrfs_add_ordered_extent(inode, file_offset, start, len,
 223                                           disk_len, type, 0);
 224 }
 225
 226 int btrfs_add_ordered_extent_dio(struct inode *inode, u64 file_offset,
 227                                  u64 start, u64 len, u64 disk_len, int type)
 228 {
 229         return __btrfs_add_ordered_extent(inode, file_offset, start, len,
 230                                           disk_len, type, 1);
 231 }
 232
 233 /*
 234  * Add a struct btrfs_ordered_sum into the list of checksums to be inserted
 235  * when an ordered extent is finished.  If the list covers more than one
 236  * ordered extent, it is split across multiples.
 237  */
 238 int btrfs_add_ordered_sum(struct inode *inode,
 239                           struct btrfs_ordered_extent *entry,
 240                           struct btrfs_ordered_sum *sum)
 241 {
 242         struct btrfs_ordered_inode_tree *tree;
 243
 244         tree = &BTRFS_I(inode)->ordered_tree;
 245         spin_lock(&tree->lock);
 246         list_add_tail(&sum->list, &entry->list);
 247         spin_unlock(&tree->lock);
 248         return 0;
 249 }
 250
 251 /*
 252  * this is used to account for finished IO across a given range
 253  * of the file.  The IO should not span ordered extents.  If
 254  * a given ordered_extent is completely done, 1 is returned, otherwise
 255  * 0.
 256  *
 257  * test_and_set_bit on a flag in the struct btrfs_ordered_extent is used
 258  * to make sure this function only returns 1 once for a given ordered extent.
 259  */
 260 int btrfs_dec_test_ordered_pending(struct inode *inode,
 261                                    struct btrfs_ordered_extent **cached,
 262                                    u64 file_offset, u64 io_size)
 263 {
 264         struct btrfs_ordered_inode_tree *tree;
 265         struct rb_node *node;
 266         struct btrfs_ordered_extent *entry = NULL;
 267         int ret;
 268
 269         tree = &BTRFS_I(inode)->ordered_tree;
 270         spin_lock(&tree->lock);
 271         node = tree_search(tree, file_offset);
 272         if (!node) {
 273                 ret = 1;
 274                 goto out;
 275         }
 276
 277         entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
 278         if (!offset_in_entry(entry, file_offset)) {
 279                 ret = 1;
 280                 goto out;
 281         }
 282
 283         if (io_size > entry->bytes_left) {
 284                 printk(KERN_CRIT "bad ordered accounting left %llu size %llu\n",
 285                        (unsigned long long)entry->bytes_left,
 286                        (unsigned long long)io_size);
 287         }
 288         entry->bytes_left -= io_size;
 289         if (entry->bytes_left == 0)
 290                 ret = test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags);
 291         else
 292                 ret = 1;
 293 out:
 294         if (!ret && cached && entry) {
 295                 *cached = entry;
 296                 atomic_inc(&entry->refs);
 297         }
 298         spin_unlock(&tree->lock);
 299         return ret == 0;
 300 }
 301
 302 /*
 303  * used to drop a reference on an ordered extent.  This will free
 304  * the extent if the last reference is dropped
 305  */
 306 int btrfs_put_ordered_extent(struct btrfs_ordered_extent *entry)
 307 {
 308         struct list_head *cur;
 309         struct btrfs_ordered_sum *sum;
 310
 311         if (atomic_dec_and_test(&entry->refs)) {
 312                 while (!list_empty(&entry->list)) {
 313                         cur = entry->list.next;
 314                         sum = list_entry(cur, struct btrfs_ordered_sum, list);
 315                         list_del(&sum->list);
 316                         kfree(sum);
 317                 }
 318                 kfree(entry);
 319         }
 320         return 0;
 321 }
 322
 323 /*
 324  * remove an ordered extent from the tree.  No references are dropped
 325  * and you must wake_up entry->wait.  You must hold the tree lock
 326  * while you call this function.
 327  */
 328 static int __btrfs_remove_ordered_extent(struct inode *inode,
 329                                 struct btrfs_ordered_extent *entry)
 330 {
 331         struct btrfs_ordered_inode_tree *tree;
 332         struct btrfs_root *root = BTRFS_I(inode)->root;
 333         struct rb_node *node;
 334
 335         tree = &BTRFS_I(inode)->ordered_tree;
 336         node = &entry->rb_node;
 337         rb_erase(node, &tree->tree);
 338         tree->last = NULL;
 339         set_bit(BTRFS_ORDERED_COMPLETE, &entry->flags);
 340
 341         spin_lock(&root->fs_info->ordered_extent_lock);
 342         list_del_init(&entry->root_extent_list);
 343
 344         /*
 345          * we have no more ordered extents for this inode and
 346          * no dirty pages.  We can safely remove it from the
 347          * list of ordered extents
 348          */
 349         if (RB_EMPTY_ROOT(&tree->tree) &&
 350             !mapping_tagged(inode->i_mapping, PAGECACHE_TAG_DIRTY)) {
 351                 list_del_init(&BTRFS_I(inode)->ordered_operations);
 352         }
 353         spin_unlock(&root->fs_info->ordered_extent_lock);
 354
 355         return 0;
 356 }
 357
 358 /*
 359  * remove an ordered extent from the tree.  No references are dropped
 360  * but any waiters are woken.
 361  */
 362 int btrfs_remove_ordered_extent(struct inode *inode,
 363                                 struct btrfs_ordered_extent *entry)
 364 {
 365         struct btrfs_ordered_inode_tree *tree;
 366         int ret;
 367
 368         tree = &BTRFS_I(inode)->ordered_tree;
 369         spin_lock(&tree->lock);
 370         ret = __btrfs_remove_ordered_extent(inode, entry);
 371         spin_unlock(&tree->lock);
 372         wake_up(&entry->wait);
 373
 374         return ret;
 375 }
 376
 377 /*
 378  * wait for all the ordered extents in a root.  This is done when balancing
 379  * space between drives.
 380  */
 381 int btrfs_wait_ordered_extents(struct btrfs_root *root,
 382                                int nocow_only, int delay_iput)
 383 {
 384         struct list_head splice;
 385         struct list_head *cur;
 386         struct btrfs_ordered_extent *ordered;
 387         struct inode *inode;
 388
 389         INIT_LIST_HEAD(&splice);
 390
 391         spin_lock(&root->fs_info->ordered_extent_lock);
 392         list_splice_init(&root->fs_info->ordered_extents, &splice);
 393         while (!list_empty(&splice)) {
 394                 cur = splice.next;
 395                 ordered = list_entry(cur, struct btrfs_ordered_extent,
 396                                      root_extent_list);
 397                 if (nocow_only &&
 398                     !test_bit(BTRFS_ORDERED_NOCOW, &ordered->flags) &&
 399                     !test_bit(BTRFS_ORDERED_PREALLOC, &ordered->flags)) {
 400                         list_move(&ordered->root_extent_list,
 401                                   &root->fs_info->ordered_extents);
 402                         cond_resched_lock(&root->fs_info->ordered_extent_lock);
 403                         continue;
 404                 }
 405
 406                 list_del_init(&ordered->root_extent_list);
 407                 atomic_inc(&ordered->refs);
 408
 409                 /*
 410                  * the inode may be getting freed (in sys_unlink path).
 411                  */
 412                 inode = igrab(ordered->inode);
 413
 414                 spin_unlock(&root->fs_info->ordered_extent_lock);
 415
 416                 if (inode) {
 417                         btrfs_start_ordered_extent(inode, ordered, 1);
 418                         btrfs_put_ordered_extent(ordered);
 419                         if (delay_iput)
 420                                 btrfs_add_delayed_iput(inode);
 421                         else
 422                                 iput(inode);
 423                 } else {
 424                         btrfs_put_ordered_extent(ordered);
 425                 }
 426
 427                 spin_lock(&root->fs_info->ordered_extent_lock);
 428         }
 429         spin_unlock(&root->fs_info->ordered_extent_lock);
 430         return 0;
 431 }
 432
 433 /*
 434  * this is used during transaction commit to write all the inodes
 435  * added to the ordered operation list.  These files must be fully on
 436  * disk before the transaction commits.
 437  *
 438  * we have two modes here, one is to just start the IO via filemap_flush
 439  * and the other is to wait for all the io.  When we wait, we have an
 440  * extra check to make sure the ordered operation list really is empty
 441  * before we return
 442  */
 443 int btrfs_run_ordered_operations(struct btrfs_root *root, int wait)
 444 {
 445         struct btrfs_inode *btrfs_inode;
 446         struct inode *inode;
 447         struct list_head splice;
 448
 449         INIT_LIST_HEAD(&splice);
 450
 451         mutex_lock(&root->fs_info->ordered_operations_mutex);
 452         spin_lock(&root->fs_info->ordered_extent_lock);
 453 again:
 454         list_splice_init(&root->fs_info->ordered_operations, &splice);
 455
 456         while (!list_empty(&splice)) {
 457                 btrfs_inode = list_entry(splice.next, struct btrfs_inode,
 458                                    ordered_operations);
 459
 460                 inode = &btrfs_inode->vfs_inode;
 461
 462                 list_del_init(&btrfs_inode->ordered_operations);
 463
 464                 /*
 465                  * the inode may be getting freed (in sys_unlink path).
 466                  */
 467                 inode = igrab(inode);
 468
 469                 if (!wait && inode) {
 470                         list_add_tail(&BTRFS_I(inode)->ordered_operations,
 471                               &root->fs_info->ordered_operations);
 472                 }
 473                 spin_unlock(&root->fs_info->ordered_extent_lock);
 474
 475                 if (inode) {
 476                         if (wait)
 477                                 btrfs_wait_ordered_range(inode, 0, (u64)-1);
 478                         else
 479                                 filemap_flush(inode->i_mapping);
 480                         btrfs_add_delayed_iput(inode);
 481                 }
 482
 483                 cond_resched();
 484                 spin_lock(&root->fs_info->ordered_extent_lock);
 485         }
 486         if (wait && !list_empty(&root->fs_info->ordered_operations))
 487                 goto again;
 488
 489         spin_unlock(&root->fs_info->ordered_extent_lock);
 490         mutex_unlock(&root->fs_info->ordered_operations_mutex);
 491
 492         return 0;
 493 }
 494
 495 /*
 496  * Used to start IO or wait for a given ordered extent to finish.
 497  *
 498  * If wait is one, this effectively waits on page writeback for all the pages
 499  * in the extent, and it waits on the io completion code to insert
 500  * metadata into the btree corresponding to the extent
 501  */
 502 void btrfs_start_ordered_extent(struct inode *inode,
 503                                        struct btrfs_ordered_extent *entry,
 504                                        int wait)
 505 {
 506         u64 start = entry->file_offset;
 507         u64 end = start + entry->len - 1;
 508
 509         /*
 510          * pages in the range can be dirty, clean or writeback.  We
 511          * start IO on any dirty ones so the wait doesn't stall waiting
 512          * for pdflush to find them
 513          */
 514         if (!test_bit(BTRFS_ORDERED_DIRECT, &entry->flags))
 515                 filemap_fdatawrite_range(inode->i_mapping, start, end);
 516         if (wait) {
 517                 wait_event(entry->wait, test_bit(BTRFS_ORDERED_COMPLETE,
 518                                                  &entry->flags));
 519         }
 520 }
 521
 522 /*
 523  * Used to wait on ordered extents across a large range of bytes.
 524  */
 525 int btrfs_wait_ordered_range(struct inode *inode, u64 start, u64 len)
 526 {
 527         u64 end;
 528         u64 orig_end;
 529         u64 wait_end;
 530         struct btrfs_ordered_extent *ordered;
 531         int found;
 532
 533         if (start + len < start) {
 534                 orig_end = INT_LIMIT(loff_t);
 535         } else {
 536                 orig_end = start + len - 1;
 537                 if (orig_end > INT_LIMIT(loff_t))
 538                         orig_end = INT_LIMIT(loff_t);
 539         }
 540         wait_end = orig_end;
 541 again:
 542         /* start IO across the range first to instantiate any delalloc
 543          * extents
 544          */
 545         filemap_fdatawrite_range(inode->i_mapping, start, orig_end);
 546
 547         /* The compression code will leave pages locked but return from
 548          * writepage without setting the page writeback.  Starting again
 549          * with WB_SYNC_ALL will end up waiting for the IO to actually start.
 550          */
 551         filemap_fdatawrite_range(inode->i_mapping, start, orig_end);
 552
 553         filemap_fdatawait_range(inode->i_mapping, start, orig_end);
 554
 555         end = orig_end;
 556         found = 0;
 557         while (1) {
 558                 ordered = btrfs_lookup_first_ordered_extent(inode, end);
 559                 if (!ordered)
 560                         break;
 561                 if (ordered->file_offset > orig_end) {
 562                         btrfs_put_ordered_extent(ordered);
 563                         break;
 564                 }
 565                 if (ordered->file_offset + ordered->len < start) {
 566                         btrfs_put_ordered_extent(ordered);
 567                         break;
 568                 }
 569                 found++;
 570                 btrfs_start_ordered_extent(inode, ordered, 1);
 571                 end = ordered->file_offset;
 572                 btrfs_put_ordered_extent(ordered);
 573                 if (end == 0 || end == start)
 574                         break;
 575                 end--;
 576         }
 577         if (found || test_range_bit(&BTRFS_I(inode)->io_tree, start, orig_end,
 578                            EXTENT_DELALLOC, 0, NULL)) {
 579                 schedule_timeout(1);
 580                 goto again;
 581         }
 582         return 0;
 583 }
 584
 585 /*
 586  * find an ordered extent corresponding to file_offset.  return NULL if
 587  * nothing is found, otherwise take a reference on the extent and return it
 588  */
 589 struct btrfs_ordered_extent *btrfs_lookup_ordered_extent(struct inode *inode,
 590                                                          u64 file_offset)
 591 {
 592         struct btrfs_ordered_inode_tree *tree;
 593         struct rb_node *node;
 594         struct btrfs_ordered_extent *entry = NULL;
 595
 596         tree = &BTRFS_I(inode)->ordered_tree;
 597         spin_lock(&tree->lock);
 598         node = tree_search(tree, file_offset);
 599         if (!node)
 600                 goto out;
 601
 602         entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
 603         if (!offset_in_entry(entry, file_offset))
 604                 entry = NULL;
 605         if (entry)
 606                 atomic_inc(&entry->refs);
 607 out:
 608         spin_unlock(&tree->lock);
 609         return entry;
 610 }
 611
 612 /* Since the DIO code tries to lock a wide area we need to look for any ordered
 613  * extents that exist in the range, rather than just the start of the range.
 614  */
 615 struct btrfs_ordered_extent *btrfs_lookup_ordered_range(struct inode *inode,
 616                                                         u64 file_offset,
 617                                                         u64 len)
 618 {
 619         struct btrfs_ordered_inode_tree *tree;
 620         struct rb_node *node;
 621         struct btrfs_ordered_extent *entry = NULL;
 622
 623         tree = &BTRFS_I(inode)->ordered_tree;
 624         spin_lock(&tree->lock);
 625         node = tree_search(tree, file_offset);
 626         if (!node) {
 627                 node = tree_search(tree, file_offset + len);
 628                 if (!node)
 629                         goto out;
 630         }
 631
 632         while (1) {
 633                 entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
 634                 if (range_overlaps(entry, file_offset, len))
 635                         break;
 636
 637                 if (entry->file_offset >= file_offset + len) {
 638                         entry = NULL;
 639                         break;
 640                 }
 641                 entry = NULL;
 642                 node = rb_next(node);
 643                 if (!node)
 644                         break;
 645         }
 646 out:
 647         if (entry)
 648                 atomic_inc(&entry->refs);
 649         spin_unlock(&tree->lock);
 650         return entry;
 651 }
 652
 653 /*
 654  * lookup and return any extent before 'file_offset'.  NULL is returned
 655  * if none is found
 656  */
 657 struct btrfs_ordered_extent *
 658 btrfs_lookup_first_ordered_extent(struct inode *inode, u64 file_offset)
 659 {
 660         struct btrfs_ordered_inode_tree *tree;
 661         struct rb_node *node;
 662         struct btrfs_ordered_extent *entry = NULL;
 663
 664         tree = &BTRFS_I(inode)->ordered_tree;
 665         spin_lock(&tree->lock);
 666         node = tree_search(tree, file_offset);
 667         if (!node)
 668                 goto out;
 669
 670         entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
 671         atomic_inc(&entry->refs);
 672 out:
 673         spin_unlock(&tree->lock);
 674         return entry;
 675 }
 676
 677 /*
 678  * After an extent is done, call this to conditionally update the on disk
 679  * i_size.  i_size is updated to cover any fully written part of the file.
 680  */
 681 int btrfs_ordered_update_i_size(struct inode *inode, u64 offset,
 682                                 struct btrfs_ordered_extent *ordered)
 683 {
 684         struct btrfs_ordered_inode_tree *tree = &BTRFS_I(inode)->ordered_tree;
 685         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 686         u64 disk_i_size;
 687         u64 new_i_size;
 688         u64 i_size_test;
 689         u64 i_size = i_size_read(inode);
 690         struct rb_node *node;
 691         struct rb_node *prev = NULL;
 692         struct btrfs_ordered_extent *test;
 693         int ret = 1;
 694
 695         if (ordered)
 696                 offset = entry_end(ordered);
 697         else
 698                 offset = ALIGN(offset, BTRFS_I(inode)->root->sectorsize);
 699
 700         spin_lock(&tree->lock);
 701         disk_i_size = BTRFS_I(inode)->disk_i_size;
 702
 703         /* truncate file */
 704         if (disk_i_size > i_size) {
 705                 BTRFS_I(inode)->disk_i_size = i_size;
 706                 ret = 0;
 707                 goto out;
 708         }
 709
 710         /*
 711          * if the disk i_size is already at the inode->i_size, or
 712          * this ordered extent is inside the disk i_size, we're done
 713          */
 714         if (disk_i_size == i_size || offset <= disk_i_size) {
 715                 goto out;
 716         }
 717
 718         /*
 719          * we can't update the disk_isize if there are delalloc bytes
 720          * between disk_i_size and  this ordered extent
 721          */
 722         if (test_range_bit(io_tree, disk_i_size, offset - 1,
 723                            EXTENT_DELALLOC, 0, NULL)) {
 724                 goto out;
 725         }
 726         /*
 727          * walk backward from this ordered extent to disk_i_size.
 728          * if we find an ordered extent then we can't update disk i_size
 729          * yet
 730          */
 731         if (ordered) {
 732                 node = rb_prev(&ordered->rb_node);
 733         } else {
 734                 prev = tree_search(tree, offset);
 735                 /*
 736                  * we insert file extents without involving ordered struct,
 737                  * so there should be no ordered struct cover this offset
 738                  */
 739                 if (prev) {
 740                         test = rb_entry(prev, struct btrfs_ordered_extent,
 741                                         rb_node);
 742                         BUG_ON(offset_in_entry(test, offset));
 743                 }
 744                 node = prev;
 745         }
 746         while (node) {
 747                 test = rb_entry(node, struct btrfs_ordered_extent, rb_node);
 748                 if (test->file_offset + test->len <= disk_i_size)
 749                         break;
 750                 if (test->file_offset >= i_size)
 751                         break;
 752                 if (test->file_offset >= disk_i_size)
 753                         goto out;
 754                 node = rb_prev(node);
 755         }
 756         new_i_size = min_t(u64, offset, i_size);
 757
 758         /*
 759          * at this point, we know we can safely update i_size to at least
 760          * the offset from this ordered extent.  But, we need to
 761          * walk forward and see if ios from higher up in the file have
 762          * finished.
 763          */
 764         if (ordered) {
 765                 node = rb_next(&ordered->rb_node);
 766         } else {
 767                 if (prev)
 768                         node = rb_next(prev);
 769                 else
 770                         node = rb_first(&tree->tree);
 771         }
 772         i_size_test = 0;
 773         if (node) {
 774                 /*
 775                  * do we have an area where IO might have finished
 776                  * between our ordered extent and the next one.
 777                  */
 778                 test = rb_entry(node, struct btrfs_ordered_extent, rb_node);
 779                 if (test->file_offset > offset)
 780                         i_size_test = test->file_offset;
 781         } else {
 782                 i_size_test = i_size;
 783         }
 784
 785         /*
 786          * i_size_test is the end of a region after this ordered
 787          * extent where there are no ordered extents.  As long as there
 788          * are no delalloc bytes in this area, it is safe to update
 789          * disk_i_size to the end of the region.
 790          */
 791         if (i_size_test > offset &&
 792             !test_range_bit(io_tree, offset, i_size_test - 1,
 793                             EXTENT_DELALLOC, 0, NULL)) {
 794                 new_i_size = min_t(u64, i_size_test, i_size);
 795         }
 796         BTRFS_I(inode)->disk_i_size = new_i_size;
 797         ret = 0;
 798 out:
 799         /*
 800          * we need to remove the ordered extent with the tree lock held
 801          * so that other people calling this function don't find our fully
 802          * processed ordered entry and skip updating the i_size
 803          */
 804         if (ordered)
 805                 __btrfs_remove_ordered_extent(inode, ordered);
 806         spin_unlock(&tree->lock);
 807         if (ordered)
 808                 wake_up(&ordered->wait);
 809         return ret;
 810 }
 811
 812 /*
 813  * search the ordered extents for one corresponding to 'offset' and
 814  * try to find a checksum.  This is used because we allow pages to
 815  * be reclaimed before their checksum is actually put into the btree
 816  */
 817 int btrfs_find_ordered_sum(struct inode *inode, u64 offset, u64 disk_bytenr,
 818                            u32 *sum)
 819 {
 820         struct btrfs_ordered_sum *ordered_sum;
 821         struct btrfs_sector_sum *sector_sums;
 822         struct btrfs_ordered_extent *ordered;
 823         struct btrfs_ordered_inode_tree *tree = &BTRFS_I(inode)->ordered_tree;
 824         unsigned long num_sectors;
 825         unsigned long i;
 826         u32 sectorsize = BTRFS_I(inode)->root->sectorsize;
 827         int ret = 1;
 828
 829         ordered = btrfs_lookup_ordered_extent(inode, offset);
 830         if (!ordered)
 831                 return 1;
 832
 833         spin_lock(&tree->lock);
 834         list_for_each_entry_reverse(ordered_sum, &ordered->list, list) {
 835                 if (disk_bytenr >= ordered_sum->bytenr) {
 836                         num_sectors = ordered_sum->len / sectorsize;
 837                         sector_sums = ordered_sum->sums;
 838                         for (i = 0; i < num_sectors; i++) {
 839                                 if (sector_sums[i].bytenr == disk_bytenr) {
 840                                         *sum = sector_sums[i].sum;
 841                                         ret = 0;
 842                                         goto out;
 843                                 }
 844                         }
 845                 }
 846         }
 847 out:
 848         spin_unlock(&tree->lock);
 849         btrfs_put_ordered_extent(ordered);
 850         return ret;
 851 }
 852
 853
 854 /*
 855  * add a given inode to the list of inodes that must be fully on
 856  * disk before a transaction commit finishes.
 857  *
 858  * This basically gives us the ext3 style data=ordered mode, and it is mostly
 859  * used to make sure renamed files are fully on disk.
 860  *
 861  * It is a noop if the inode is already fully on disk.
 862  *
 863  * If trans is not null, we'll do a friendly check for a transaction that
 864  * is already flushing things and force the IO down ourselves.
 865  */
 866 int btrfs_add_ordered_operation(struct btrfs_trans_handle *trans,
 867                                 struct btrfs_root *root,
 868                                 struct inode *inode)
 869 {
 870         u64 last_mod;
 871
 872         last_mod = max(BTRFS_I(inode)->generation, BTRFS_I(inode)->last_trans);
 873
 874         /*
 875          * if this file hasn't been changed since the last transaction
 876          * commit, we can safely return without doing anything
 877          */
 878         if (last_mod < root->fs_info->last_trans_committed)
 879                 return 0;
 880
 881         /*
 882          * the transaction is already committing.  Just start the IO and
 883          * don't bother with all of this list nonsense
 884          */
 885         if (trans && root->fs_info->running_transaction->blocked) {
 886                 btrfs_wait_ordered_range(inode, 0, (u64)-1);
 887                 return 0;
 888         }
 889
 890         spin_lock(&root->fs_info->ordered_extent_lock);
 891         if (list_empty(&BTRFS_I(inode)->ordered_operations)) {
 892                 list_add_tail(&BTRFS_I(inode)->ordered_operations,
 893                               &root->fs_info->ordered_operations);
 894         }
 895         spin_unlock(&root->fs_info->ordered_extent_lock);
 896
 897         return 0;
 898 }