linux/fs/btrfs/ordered-data.c
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   1/*
   2 * Copyright (C) 2007 Oracle.  All rights reserved.
   3 *
   4 * This program is free software; you can redistribute it and/or
   5 * modify it under the terms of the GNU General Public
   6 * License v2 as published by the Free Software Foundation.
   7 *
   8 * This program is distributed in the hope that it will be useful,
   9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11 * General Public License for more details.
  12 *
  13 * You should have received a copy of the GNU General Public
  14 * License along with this program; if not, write to the
  15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16 * Boston, MA 021110-1307, USA.
  17 */
  18
  19#include <linux/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
  28static 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 */
  38static 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
  62static void ordered_data_tree_panic(struct inode *inode, int errno,
  63                                               u64 offset)
  64{
  65        struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  66        btrfs_panic(fs_info, errno, "Inconsistency in ordered tree at offset "
  67                    "%llu\n", (unsigned long long)offset);
  68}
  69
  70/*
  71 * look for a given offset in the tree, and if it can't be found return the
  72 * first lesser offset
  73 */
  74static struct rb_node *__tree_search(struct rb_root *root, u64 file_offset,
  75                                     struct rb_node **prev_ret)
  76{
  77        struct rb_node *n = root->rb_node;
  78        struct rb_node *prev = NULL;
  79        struct rb_node *test;
  80        struct btrfs_ordered_extent *entry;
  81        struct btrfs_ordered_extent *prev_entry = NULL;
  82
  83        while (n) {
  84                entry = rb_entry(n, struct btrfs_ordered_extent, rb_node);
  85                prev = n;
  86                prev_entry = entry;
  87
  88                if (file_offset < entry->file_offset)
  89                        n = n->rb_left;
  90                else if (file_offset >= entry_end(entry))
  91                        n = n->rb_right;
  92                else
  93                        return n;
  94        }
  95        if (!prev_ret)
  96                return NULL;
  97
  98        while (prev && file_offset >= entry_end(prev_entry)) {
  99                test = rb_next(prev);
 100                if (!test)
 101                        break;
 102                prev_entry = rb_entry(test, struct btrfs_ordered_extent,
 103                                      rb_node);
 104                if (file_offset < entry_end(prev_entry))
 105                        break;
 106
 107                prev = test;
 108        }
 109        if (prev)
 110                prev_entry = rb_entry(prev, struct btrfs_ordered_extent,
 111                                      rb_node);
 112        while (prev && file_offset < entry_end(prev_entry)) {
 113                test = rb_prev(prev);
 114                if (!test)
 115                        break;
 116                prev_entry = rb_entry(test, struct btrfs_ordered_extent,
 117                                      rb_node);
 118                prev = test;
 119        }
 120        *prev_ret = prev;
 121        return NULL;
 122}
 123
 124/*
 125 * helper to check if a given offset is inside a given entry
 126 */
 127static int offset_in_entry(struct btrfs_ordered_extent *entry, u64 file_offset)
 128{
 129        if (file_offset < entry->file_offset ||
 130            entry->file_offset + entry->len <= file_offset)
 131                return 0;
 132        return 1;
 133}
 134
 135static int range_overlaps(struct btrfs_ordered_extent *entry, u64 file_offset,
 136                          u64 len)
 137{
 138        if (file_offset + len <= entry->file_offset ||
 139            entry->file_offset + entry->len <= file_offset)
 140                return 0;
 141        return 1;
 142}
 143
 144/*
 145 * look find the first ordered struct that has this offset, otherwise
 146 * the first one less than this offset
 147 */
 148static inline struct rb_node *tree_search(struct btrfs_ordered_inode_tree *tree,
 149                                          u64 file_offset)
 150{
 151        struct rb_root *root = &tree->tree;
 152        struct rb_node *prev = NULL;
 153        struct rb_node *ret;
 154        struct btrfs_ordered_extent *entry;
 155
 156        if (tree->last) {
 157                entry = rb_entry(tree->last, struct btrfs_ordered_extent,
 158                                 rb_node);
 159                if (offset_in_entry(entry, file_offset))
 160                        return tree->last;
 161        }
 162        ret = __tree_search(root, file_offset, &prev);
 163        if (!ret)
 164                ret = prev;
 165        if (ret)
 166                tree->last = ret;
 167        return ret;
 168}
 169
 170/* allocate and add a new ordered_extent into the per-inode tree.
 171 * file_offset is the logical offset in the file
 172 *
 173 * start is the disk block number of an extent already reserved in the
 174 * extent allocation tree
 175 *
 176 * len is the length of the extent
 177 *
 178 * The tree is given a single reference on the ordered extent that was
 179 * inserted.
 180 */
 181static int __btrfs_add_ordered_extent(struct inode *inode, u64 file_offset,
 182                                      u64 start, u64 len, u64 disk_len,
 183                                      int type, int dio, int compress_type)
 184{
 185        struct btrfs_ordered_inode_tree *tree;
 186        struct rb_node *node;
 187        struct btrfs_ordered_extent *entry;
 188
 189        tree = &BTRFS_I(inode)->ordered_tree;
 190        entry = kzalloc(sizeof(*entry), GFP_NOFS);
 191        if (!entry)
 192                return -ENOMEM;
 193
 194        entry->file_offset = file_offset;
 195        entry->start = start;
 196        entry->len = len;
 197        entry->disk_len = disk_len;
 198        entry->bytes_left = len;
 199        entry->inode = igrab(inode);
 200        entry->compress_type = compress_type;
 201        if (type != BTRFS_ORDERED_IO_DONE && type != BTRFS_ORDERED_COMPLETE)
 202                set_bit(type, &entry->flags);
 203
 204        if (dio)
 205                set_bit(BTRFS_ORDERED_DIRECT, &entry->flags);
 206
 207        /* one ref for the tree */
 208        atomic_set(&entry->refs, 1);
 209        init_waitqueue_head(&entry->wait);
 210        INIT_LIST_HEAD(&entry->list);
 211        INIT_LIST_HEAD(&entry->root_extent_list);
 212
 213        trace_btrfs_ordered_extent_add(inode, entry);
 214
 215        spin_lock_irq(&tree->lock);
 216        node = tree_insert(&tree->tree, file_offset,
 217                           &entry->rb_node);
 218        if (node)
 219                ordered_data_tree_panic(inode, -EEXIST, file_offset);
 220        spin_unlock_irq(&tree->lock);
 221
 222        spin_lock(&BTRFS_I(inode)->root->fs_info->ordered_extent_lock);
 223        list_add_tail(&entry->root_extent_list,
 224                      &BTRFS_I(inode)->root->fs_info->ordered_extents);
 225        spin_unlock(&BTRFS_I(inode)->root->fs_info->ordered_extent_lock);
 226
 227        return 0;
 228}
 229
 230int btrfs_add_ordered_extent(struct inode *inode, u64 file_offset,
 231                             u64 start, u64 len, u64 disk_len, int type)
 232{
 233        return __btrfs_add_ordered_extent(inode, file_offset, start, len,
 234                                          disk_len, type, 0,
 235                                          BTRFS_COMPRESS_NONE);
 236}
 237
 238int btrfs_add_ordered_extent_dio(struct inode *inode, u64 file_offset,
 239                                 u64 start, u64 len, u64 disk_len, int type)
 240{
 241        return __btrfs_add_ordered_extent(inode, file_offset, start, len,
 242                                          disk_len, type, 1,
 243                                          BTRFS_COMPRESS_NONE);
 244}
 245
 246int btrfs_add_ordered_extent_compress(struct inode *inode, u64 file_offset,
 247                                      u64 start, u64 len, u64 disk_len,
 248                                      int type, int compress_type)
 249{
 250        return __btrfs_add_ordered_extent(inode, file_offset, start, len,
 251                                          disk_len, type, 0,
 252                                          compress_type);
 253}
 254
 255/*
 256 * Add a struct btrfs_ordered_sum into the list of checksums to be inserted
 257 * when an ordered extent is finished.  If the list covers more than one
 258 * ordered extent, it is split across multiples.
 259 */
 260void btrfs_add_ordered_sum(struct inode *inode,
 261                           struct btrfs_ordered_extent *entry,
 262                           struct btrfs_ordered_sum *sum)
 263{
 264        struct btrfs_ordered_inode_tree *tree;
 265
 266        tree = &BTRFS_I(inode)->ordered_tree;
 267        spin_lock_irq(&tree->lock);
 268        list_add_tail(&sum->list, &entry->list);
 269        spin_unlock_irq(&tree->lock);
 270}
 271
 272/*
 273 * this is used to account for finished IO across a given range
 274 * of the file.  The IO may span ordered extents.  If
 275 * a given ordered_extent is completely done, 1 is returned, otherwise
 276 * 0.
 277 *
 278 * test_and_set_bit on a flag in the struct btrfs_ordered_extent is used
 279 * to make sure this function only returns 1 once for a given ordered extent.
 280 *
 281 * file_offset is updated to one byte past the range that is recorded as
 282 * complete.  This allows you to walk forward in the file.
 283 */
 284int btrfs_dec_test_first_ordered_pending(struct inode *inode,
 285                                   struct btrfs_ordered_extent **cached,
 286                                   u64 *file_offset, u64 io_size, int uptodate)
 287{
 288        struct btrfs_ordered_inode_tree *tree;
 289        struct rb_node *node;
 290        struct btrfs_ordered_extent *entry = NULL;
 291        int ret;
 292        unsigned long flags;
 293        u64 dec_end;
 294        u64 dec_start;
 295        u64 to_dec;
 296
 297        tree = &BTRFS_I(inode)->ordered_tree;
 298        spin_lock_irqsave(&tree->lock, flags);
 299        node = tree_search(tree, *file_offset);
 300        if (!node) {
 301                ret = 1;
 302                goto out;
 303        }
 304
 305        entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
 306        if (!offset_in_entry(entry, *file_offset)) {
 307                ret = 1;
 308                goto out;
 309        }
 310
 311        dec_start = max(*file_offset, entry->file_offset);
 312        dec_end = min(*file_offset + io_size, entry->file_offset +
 313                      entry->len);
 314        *file_offset = dec_end;
 315        if (dec_start > dec_end) {
 316                printk(KERN_CRIT "bad ordering dec_start %llu end %llu\n",
 317                       (unsigned long long)dec_start,
 318                       (unsigned long long)dec_end);
 319        }
 320        to_dec = dec_end - dec_start;
 321        if (to_dec > entry->bytes_left) {
 322                printk(KERN_CRIT "bad ordered accounting left %llu size %llu\n",
 323                       (unsigned long long)entry->bytes_left,
 324                       (unsigned long long)to_dec);
 325        }
 326        entry->bytes_left -= to_dec;
 327        if (!uptodate)
 328                set_bit(BTRFS_ORDERED_IOERR, &entry->flags);
 329
 330        if (entry->bytes_left == 0)
 331                ret = test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags);
 332        else
 333                ret = 1;
 334out:
 335        if (!ret && cached && entry) {
 336                *cached = entry;
 337                atomic_inc(&entry->refs);
 338        }
 339        spin_unlock_irqrestore(&tree->lock, flags);
 340        return ret == 0;
 341}
 342
 343/*
 344 * this is used to account for finished IO across a given range
 345 * of the file.  The IO should not span ordered extents.  If
 346 * a given ordered_extent is completely done, 1 is returned, otherwise
 347 * 0.
 348 *
 349 * test_and_set_bit on a flag in the struct btrfs_ordered_extent is used
 350 * to make sure this function only returns 1 once for a given ordered extent.
 351 */
 352int btrfs_dec_test_ordered_pending(struct inode *inode,
 353                                   struct btrfs_ordered_extent **cached,
 354                                   u64 file_offset, u64 io_size, int uptodate)
 355{
 356        struct btrfs_ordered_inode_tree *tree;
 357        struct rb_node *node;
 358        struct btrfs_ordered_extent *entry = NULL;
 359        unsigned long flags;
 360        int ret;
 361
 362        tree = &BTRFS_I(inode)->ordered_tree;
 363        spin_lock_irqsave(&tree->lock, flags);
 364        if (cached && *cached) {
 365                entry = *cached;
 366                goto have_entry;
 367        }
 368
 369        node = tree_search(tree, file_offset);
 370        if (!node) {
 371                ret = 1;
 372                goto out;
 373        }
 374
 375        entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
 376have_entry:
 377        if (!offset_in_entry(entry, file_offset)) {
 378                ret = 1;
 379                goto out;
 380        }
 381
 382        if (io_size > entry->bytes_left) {
 383                printk(KERN_CRIT "bad ordered accounting left %llu size %llu\n",
 384                       (unsigned long long)entry->bytes_left,
 385                       (unsigned long long)io_size);
 386        }
 387        entry->bytes_left -= io_size;
 388        if (!uptodate)
 389                set_bit(BTRFS_ORDERED_IOERR, &entry->flags);
 390
 391        if (entry->bytes_left == 0)
 392                ret = test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags);
 393        else
 394                ret = 1;
 395out:
 396        if (!ret && cached && entry) {
 397                *cached = entry;
 398                atomic_inc(&entry->refs);
 399        }
 400        spin_unlock_irqrestore(&tree->lock, flags);
 401        return ret == 0;
 402}
 403
 404/*
 405 * used to drop a reference on an ordered extent.  This will free
 406 * the extent if the last reference is dropped
 407 */
 408void btrfs_put_ordered_extent(struct btrfs_ordered_extent *entry)
 409{
 410        struct list_head *cur;
 411        struct btrfs_ordered_sum *sum;
 412
 413        trace_btrfs_ordered_extent_put(entry->inode, entry);
 414
 415        if (atomic_dec_and_test(&entry->refs)) {
 416                if (entry->inode)
 417                        btrfs_add_delayed_iput(entry->inode);
 418                while (!list_empty(&entry->list)) {
 419                        cur = entry->list.next;
 420                        sum = list_entry(cur, struct btrfs_ordered_sum, list);
 421                        list_del(&sum->list);
 422                        kfree(sum);
 423                }
 424                kfree(entry);
 425        }
 426}
 427
 428/*
 429 * remove an ordered extent from the tree.  No references are dropped
 430 * and waiters are woken up.
 431 */
 432void btrfs_remove_ordered_extent(struct inode *inode,
 433                                 struct btrfs_ordered_extent *entry)
 434{
 435        struct btrfs_ordered_inode_tree *tree;
 436        struct btrfs_root *root = BTRFS_I(inode)->root;
 437        struct rb_node *node;
 438
 439        tree = &BTRFS_I(inode)->ordered_tree;
 440        spin_lock_irq(&tree->lock);
 441        node = &entry->rb_node;
 442        rb_erase(node, &tree->tree);
 443        tree->last = NULL;
 444        set_bit(BTRFS_ORDERED_COMPLETE, &entry->flags);
 445        spin_unlock_irq(&tree->lock);
 446
 447        spin_lock(&root->fs_info->ordered_extent_lock);
 448        list_del_init(&entry->root_extent_list);
 449
 450        trace_btrfs_ordered_extent_remove(inode, entry);
 451
 452        /*
 453         * we have no more ordered extents for this inode and
 454         * no dirty pages.  We can safely remove it from the
 455         * list of ordered extents
 456         */
 457        if (RB_EMPTY_ROOT(&tree->tree) &&
 458            !mapping_tagged(inode->i_mapping, PAGECACHE_TAG_DIRTY)) {
 459                list_del_init(&BTRFS_I(inode)->ordered_operations);
 460        }
 461        spin_unlock(&root->fs_info->ordered_extent_lock);
 462        wake_up(&entry->wait);
 463}
 464
 465/*
 466 * wait for all the ordered extents in a root.  This is done when balancing
 467 * space between drives.
 468 */
 469void btrfs_wait_ordered_extents(struct btrfs_root *root,
 470                                int nocow_only, int delay_iput)
 471{
 472        struct list_head splice;
 473        struct list_head *cur;
 474        struct btrfs_ordered_extent *ordered;
 475        struct inode *inode;
 476
 477        INIT_LIST_HEAD(&splice);
 478
 479        spin_lock(&root->fs_info->ordered_extent_lock);
 480        list_splice_init(&root->fs_info->ordered_extents, &splice);
 481        while (!list_empty(&splice)) {
 482                cur = splice.next;
 483                ordered = list_entry(cur, struct btrfs_ordered_extent,
 484                                     root_extent_list);
 485                if (nocow_only &&
 486                    !test_bit(BTRFS_ORDERED_NOCOW, &ordered->flags) &&
 487                    !test_bit(BTRFS_ORDERED_PREALLOC, &ordered->flags)) {
 488                        list_move(&ordered->root_extent_list,
 489                                  &root->fs_info->ordered_extents);
 490                        cond_resched_lock(&root->fs_info->ordered_extent_lock);
 491                        continue;
 492                }
 493
 494                list_del_init(&ordered->root_extent_list);
 495                atomic_inc(&ordered->refs);
 496
 497                /*
 498                 * the inode may be getting freed (in sys_unlink path).
 499                 */
 500                inode = igrab(ordered->inode);
 501
 502                spin_unlock(&root->fs_info->ordered_extent_lock);
 503
 504                if (inode) {
 505                        btrfs_start_ordered_extent(inode, ordered, 1);
 506                        btrfs_put_ordered_extent(ordered);
 507                        if (delay_iput)
 508                                btrfs_add_delayed_iput(inode);
 509                        else
 510                                iput(inode);
 511                } else {
 512                        btrfs_put_ordered_extent(ordered);
 513                }
 514
 515                spin_lock(&root->fs_info->ordered_extent_lock);
 516        }
 517        spin_unlock(&root->fs_info->ordered_extent_lock);
 518}
 519
 520/*
 521 * this is used during transaction commit to write all the inodes
 522 * added to the ordered operation list.  These files must be fully on
 523 * disk before the transaction commits.
 524 *
 525 * we have two modes here, one is to just start the IO via filemap_flush
 526 * and the other is to wait for all the io.  When we wait, we have an
 527 * extra check to make sure the ordered operation list really is empty
 528 * before we return
 529 */
 530void btrfs_run_ordered_operations(struct btrfs_root *root, int wait)
 531{
 532        struct btrfs_inode *btrfs_inode;
 533        struct inode *inode;
 534        struct list_head splice;
 535
 536        INIT_LIST_HEAD(&splice);
 537
 538        mutex_lock(&root->fs_info->ordered_operations_mutex);
 539        spin_lock(&root->fs_info->ordered_extent_lock);
 540again:
 541        list_splice_init(&root->fs_info->ordered_operations, &splice);
 542
 543        while (!list_empty(&splice)) {
 544                btrfs_inode = list_entry(splice.next, struct btrfs_inode,
 545                                   ordered_operations);
 546
 547                inode = &btrfs_inode->vfs_inode;
 548
 549                list_del_init(&btrfs_inode->ordered_operations);
 550
 551                /*
 552                 * the inode may be getting freed (in sys_unlink path).
 553                 */
 554                inode = igrab(inode);
 555
 556                if (!wait && inode) {
 557                        list_add_tail(&BTRFS_I(inode)->ordered_operations,
 558                              &root->fs_info->ordered_operations);
 559                }
 560                spin_unlock(&root->fs_info->ordered_extent_lock);
 561
 562                if (inode) {
 563                        if (wait)
 564                                btrfs_wait_ordered_range(inode, 0, (u64)-1);
 565                        else
 566                                filemap_flush(inode->i_mapping);
 567                        btrfs_add_delayed_iput(inode);
 568                }
 569
 570                cond_resched();
 571                spin_lock(&root->fs_info->ordered_extent_lock);
 572        }
 573        if (wait && !list_empty(&root->fs_info->ordered_operations))
 574                goto again;
 575
 576        spin_unlock(&root->fs_info->ordered_extent_lock);
 577        mutex_unlock(&root->fs_info->ordered_operations_mutex);
 578}
 579
 580/*
 581 * Used to start IO or wait for a given ordered extent to finish.
 582 *
 583 * If wait is one, this effectively waits on page writeback for all the pages
 584 * in the extent, and it waits on the io completion code to insert
 585 * metadata into the btree corresponding to the extent
 586 */
 587void btrfs_start_ordered_extent(struct inode *inode,
 588                                       struct btrfs_ordered_extent *entry,
 589                                       int wait)
 590{
 591        u64 start = entry->file_offset;
 592        u64 end = start + entry->len - 1;
 593
 594        trace_btrfs_ordered_extent_start(inode, entry);
 595
 596        /*
 597         * pages in the range can be dirty, clean or writeback.  We
 598         * start IO on any dirty ones so the wait doesn't stall waiting
 599         * for the flusher thread to find them
 600         */
 601        if (!test_bit(BTRFS_ORDERED_DIRECT, &entry->flags))
 602                filemap_fdatawrite_range(inode->i_mapping, start, end);
 603        if (wait) {
 604                wait_event(entry->wait, test_bit(BTRFS_ORDERED_COMPLETE,
 605                                                 &entry->flags));
 606        }
 607}
 608
 609/*
 610 * Used to wait on ordered extents across a large range of bytes.
 611 */
 612void btrfs_wait_ordered_range(struct inode *inode, u64 start, u64 len)
 613{
 614        u64 end;
 615        u64 orig_end;
 616        struct btrfs_ordered_extent *ordered;
 617        int found;
 618
 619        if (start + len < start) {
 620                orig_end = INT_LIMIT(loff_t);
 621        } else {
 622                orig_end = start + len - 1;
 623                if (orig_end > INT_LIMIT(loff_t))
 624                        orig_end = INT_LIMIT(loff_t);
 625        }
 626
 627        /* start IO across the range first to instantiate any delalloc
 628         * extents
 629         */
 630        filemap_fdatawrite_range(inode->i_mapping, start, orig_end);
 631
 632        /*
 633         * So with compression we will find and lock a dirty page and clear the
 634         * first one as dirty, setup an async extent, and immediately return
 635         * with the entire range locked but with nobody actually marked with
 636         * writeback.  So we can't just filemap_write_and_wait_range() and
 637         * expect it to work since it will just kick off a thread to do the
 638         * actual work.  So we need to call filemap_fdatawrite_range _again_
 639         * since it will wait on the page lock, which won't be unlocked until
 640         * after the pages have been marked as writeback and so we're good to go
 641         * from there.  We have to do this otherwise we'll miss the ordered
 642         * extents and that results in badness.  Please Josef, do not think you
 643         * know better and pull this out at some point in the future, it is
 644         * right and you are wrong.
 645         */
 646        if (test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
 647                     &BTRFS_I(inode)->runtime_flags))
 648                filemap_fdatawrite_range(inode->i_mapping, start, orig_end);
 649
 650        filemap_fdatawait_range(inode->i_mapping, start, orig_end);
 651
 652        end = orig_end;
 653        found = 0;
 654        while (1) {
 655                ordered = btrfs_lookup_first_ordered_extent(inode, end);
 656                if (!ordered)
 657                        break;
 658                if (ordered->file_offset > orig_end) {
 659                        btrfs_put_ordered_extent(ordered);
 660                        break;
 661                }
 662                if (ordered->file_offset + ordered->len < start) {
 663                        btrfs_put_ordered_extent(ordered);
 664                        break;
 665                }
 666                found++;
 667                btrfs_start_ordered_extent(inode, ordered, 1);
 668                end = ordered->file_offset;
 669                btrfs_put_ordered_extent(ordered);
 670                if (end == 0 || end == start)
 671                        break;
 672                end--;
 673        }
 674}
 675
 676/*
 677 * find an ordered extent corresponding to file_offset.  return NULL if
 678 * nothing is found, otherwise take a reference on the extent and return it
 679 */
 680struct btrfs_ordered_extent *btrfs_lookup_ordered_extent(struct inode *inode,
 681                                                         u64 file_offset)
 682{
 683        struct btrfs_ordered_inode_tree *tree;
 684        struct rb_node *node;
 685        struct btrfs_ordered_extent *entry = NULL;
 686
 687        tree = &BTRFS_I(inode)->ordered_tree;
 688        spin_lock_irq(&tree->lock);
 689        node = tree_search(tree, file_offset);
 690        if (!node)
 691                goto out;
 692
 693        entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
 694        if (!offset_in_entry(entry, file_offset))
 695                entry = NULL;
 696        if (entry)
 697                atomic_inc(&entry->refs);
 698out:
 699        spin_unlock_irq(&tree->lock);
 700        return entry;
 701}
 702
 703/* Since the DIO code tries to lock a wide area we need to look for any ordered
 704 * extents that exist in the range, rather than just the start of the range.
 705 */
 706struct btrfs_ordered_extent *btrfs_lookup_ordered_range(struct inode *inode,
 707                                                        u64 file_offset,
 708                                                        u64 len)
 709{
 710        struct btrfs_ordered_inode_tree *tree;
 711        struct rb_node *node;
 712        struct btrfs_ordered_extent *entry = NULL;
 713
 714        tree = &BTRFS_I(inode)->ordered_tree;
 715        spin_lock_irq(&tree->lock);
 716        node = tree_search(tree, file_offset);
 717        if (!node) {
 718                node = tree_search(tree, file_offset + len);
 719                if (!node)
 720                        goto out;
 721        }
 722
 723        while (1) {
 724                entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
 725                if (range_overlaps(entry, file_offset, len))
 726                        break;
 727
 728                if (entry->file_offset >= file_offset + len) {
 729                        entry = NULL;
 730                        break;
 731                }
 732                entry = NULL;
 733                node = rb_next(node);
 734                if (!node)
 735                        break;
 736        }
 737out:
 738        if (entry)
 739                atomic_inc(&entry->refs);
 740        spin_unlock_irq(&tree->lock);
 741        return entry;
 742}
 743
 744/*
 745 * lookup and return any extent before 'file_offset'.  NULL is returned
 746 * if none is found
 747 */
 748struct btrfs_ordered_extent *
 749btrfs_lookup_first_ordered_extent(struct inode *inode, u64 file_offset)
 750{
 751        struct btrfs_ordered_inode_tree *tree;
 752        struct rb_node *node;
 753        struct btrfs_ordered_extent *entry = NULL;
 754
 755        tree = &BTRFS_I(inode)->ordered_tree;
 756        spin_lock_irq(&tree->lock);
 757        node = tree_search(tree, file_offset);
 758        if (!node)
 759                goto out;
 760
 761        entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
 762        atomic_inc(&entry->refs);
 763out:
 764        spin_unlock_irq(&tree->lock);
 765        return entry;
 766}
 767
 768/*
 769 * After an extent is done, call this to conditionally update the on disk
 770 * i_size.  i_size is updated to cover any fully written part of the file.
 771 */
 772int btrfs_ordered_update_i_size(struct inode *inode, u64 offset,
 773                                struct btrfs_ordered_extent *ordered)
 774{
 775        struct btrfs_ordered_inode_tree *tree = &BTRFS_I(inode)->ordered_tree;
 776        u64 disk_i_size;
 777        u64 new_i_size;
 778        u64 i_size_test;
 779        u64 i_size = i_size_read(inode);
 780        struct rb_node *node;
 781        struct rb_node *prev = NULL;
 782        struct btrfs_ordered_extent *test;
 783        int ret = 1;
 784
 785        if (ordered)
 786                offset = entry_end(ordered);
 787        else
 788                offset = ALIGN(offset, BTRFS_I(inode)->root->sectorsize);
 789
 790        spin_lock_irq(&tree->lock);
 791        disk_i_size = BTRFS_I(inode)->disk_i_size;
 792
 793        /* truncate file */
 794        if (disk_i_size > i_size) {
 795                BTRFS_I(inode)->disk_i_size = i_size;
 796                ret = 0;
 797                goto out;
 798        }
 799
 800        /*
 801         * if the disk i_size is already at the inode->i_size, or
 802         * this ordered extent is inside the disk i_size, we're done
 803         */
 804        if (disk_i_size == i_size || offset <= disk_i_size) {
 805                goto out;
 806        }
 807
 808        /*
 809         * walk backward from this ordered extent to disk_i_size.
 810         * if we find an ordered extent then we can't update disk i_size
 811         * yet
 812         */
 813        if (ordered) {
 814                node = rb_prev(&ordered->rb_node);
 815        } else {
 816                prev = tree_search(tree, offset);
 817                /*
 818                 * we insert file extents without involving ordered struct,
 819                 * so there should be no ordered struct cover this offset
 820                 */
 821                if (prev) {
 822                        test = rb_entry(prev, struct btrfs_ordered_extent,
 823                                        rb_node);
 824                        BUG_ON(offset_in_entry(test, offset));
 825                }
 826                node = prev;
 827        }
 828        for (; node; node = rb_prev(node)) {
 829                test = rb_entry(node, struct btrfs_ordered_extent, rb_node);
 830
 831                /* We treat this entry as if it doesnt exist */
 832                if (test_bit(BTRFS_ORDERED_UPDATED_ISIZE, &test->flags))
 833                        continue;
 834                if (test->file_offset + test->len <= disk_i_size)
 835                        break;
 836                if (test->file_offset >= i_size)
 837                        break;
 838                if (test->file_offset >= disk_i_size)
 839                        goto out;
 840        }
 841        new_i_size = min_t(u64, offset, i_size);
 842
 843        /*
 844         * at this point, we know we can safely update i_size to at least
 845         * the offset from this ordered extent.  But, we need to
 846         * walk forward and see if ios from higher up in the file have
 847         * finished.
 848         */
 849        if (ordered) {
 850                node = rb_next(&ordered->rb_node);
 851        } else {
 852                if (prev)
 853                        node = rb_next(prev);
 854                else
 855                        node = rb_first(&tree->tree);
 856        }
 857
 858        /*
 859         * We are looking for an area between our current extent and the next
 860         * ordered extent to update the i_size to.  There are 3 cases here
 861         *
 862         * 1) We don't actually have anything and we can update to i_size.
 863         * 2) We have stuff but they already did their i_size update so again we
 864         * can just update to i_size.
 865         * 3) We have an outstanding ordered extent so the most we can update
 866         * our disk_i_size to is the start of the next offset.
 867         */
 868        i_size_test = i_size;
 869        for (; node; node = rb_next(node)) {
 870                test = rb_entry(node, struct btrfs_ordered_extent, rb_node);
 871
 872                if (test_bit(BTRFS_ORDERED_UPDATED_ISIZE, &test->flags))
 873                        continue;
 874                if (test->file_offset > offset) {
 875                        i_size_test = test->file_offset;
 876                        break;
 877                }
 878        }
 879
 880        /*
 881         * i_size_test is the end of a region after this ordered
 882         * extent where there are no ordered extents, we can safely set
 883         * disk_i_size to this.
 884         */
 885        if (i_size_test > offset)
 886                new_i_size = min_t(u64, i_size_test, i_size);
 887        BTRFS_I(inode)->disk_i_size = new_i_size;
 888        ret = 0;
 889out:
 890        /*
 891         * We need to do this because we can't remove ordered extents until
 892         * after the i_disk_size has been updated and then the inode has been
 893         * updated to reflect the change, so we need to tell anybody who finds
 894         * this ordered extent that we've already done all the real work, we
 895         * just haven't completed all the other work.
 896         */
 897        if (ordered)
 898                set_bit(BTRFS_ORDERED_UPDATED_ISIZE, &ordered->flags);
 899        spin_unlock_irq(&tree->lock);
 900        return ret;
 901}
 902
 903/*
 904 * search the ordered extents for one corresponding to 'offset' and
 905 * try to find a checksum.  This is used because we allow pages to
 906 * be reclaimed before their checksum is actually put into the btree
 907 */
 908int btrfs_find_ordered_sum(struct inode *inode, u64 offset, u64 disk_bytenr,
 909                           u32 *sum)
 910{
 911        struct btrfs_ordered_sum *ordered_sum;
 912        struct btrfs_sector_sum *sector_sums;
 913        struct btrfs_ordered_extent *ordered;
 914        struct btrfs_ordered_inode_tree *tree = &BTRFS_I(inode)->ordered_tree;
 915        unsigned long num_sectors;
 916        unsigned long i;
 917        u32 sectorsize = BTRFS_I(inode)->root->sectorsize;
 918        int ret = 1;
 919
 920        ordered = btrfs_lookup_ordered_extent(inode, offset);
 921        if (!ordered)
 922                return 1;
 923
 924        spin_lock_irq(&tree->lock);
 925        list_for_each_entry_reverse(ordered_sum, &ordered->list, list) {
 926                if (disk_bytenr >= ordered_sum->bytenr) {
 927                        num_sectors = ordered_sum->len / sectorsize;
 928                        sector_sums = ordered_sum->sums;
 929                        for (i = 0; i < num_sectors; i++) {
 930                                if (sector_sums[i].bytenr == disk_bytenr) {
 931                                        *sum = sector_sums[i].sum;
 932                                        ret = 0;
 933                                        goto out;
 934                                }
 935                        }
 936                }
 937        }
 938out:
 939        spin_unlock_irq(&tree->lock);
 940        btrfs_put_ordered_extent(ordered);
 941        return ret;
 942}
 943
 944
 945/*
 946 * add a given inode to the list of inodes that must be fully on
 947 * disk before a transaction commit finishes.
 948 *
 949 * This basically gives us the ext3 style data=ordered mode, and it is mostly
 950 * used to make sure renamed files are fully on disk.
 951 *
 952 * It is a noop if the inode is already fully on disk.
 953 *
 954 * If trans is not null, we'll do a friendly check for a transaction that
 955 * is already flushing things and force the IO down ourselves.
 956 */
 957void btrfs_add_ordered_operation(struct btrfs_trans_handle *trans,
 958                                 struct btrfs_root *root, struct inode *inode)
 959{
 960        u64 last_mod;
 961
 962        last_mod = max(BTRFS_I(inode)->generation, BTRFS_I(inode)->last_trans);
 963
 964        /*
 965         * if this file hasn't been changed since the last transaction
 966         * commit, we can safely return without doing anything
 967         */
 968        if (last_mod < root->fs_info->last_trans_committed)
 969                return;
 970
 971        /*
 972         * the transaction is already committing.  Just start the IO and
 973         * don't bother with all of this list nonsense
 974         */
 975        if (trans && root->fs_info->running_transaction->blocked) {
 976                btrfs_wait_ordered_range(inode, 0, (u64)-1);
 977                return;
 978        }
 979
 980        spin_lock(&root->fs_info->ordered_extent_lock);
 981        if (list_empty(&BTRFS_I(inode)->ordered_operations)) {
 982                list_add_tail(&BTRFS_I(inode)->ordered_operations,
 983                              &root->fs_info->ordered_operations);
 984        }
 985        spin_unlock(&root->fs_info->ordered_extent_lock);
 986}
 987
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