fs/btrfs/file.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2007 Oracle.  All rights reserved.
   4  */
   5
   6 #include <linux/fs.h>
   7 #include <linux/pagemap.h>
   8 #include <linux/time.h>
   9 #include <linux/init.h>
  10 #include <linux/string.h>
  11 #include <linux/backing-dev.h>
  12 #include <linux/falloc.h>
  13 #include <linux/writeback.h>
  14 #include <linux/compat.h>
  15 #include <linux/slab.h>
  16 #include <linux/btrfs.h>
  17 #include <linux/uio.h>
  18 #include <linux/iversion.h>
  19 #include "ctree.h"
  20 #include "disk-io.h"
  21 #include "transaction.h"
  22 #include "btrfs_inode.h"
  23 #include "print-tree.h"
  24 #include "tree-log.h"
  25 #include "locking.h"
  26 #include "volumes.h"
  27 #include "qgroup.h"
  28 #include "compression.h"
  29
  30 static struct kmem_cache *btrfs_inode_defrag_cachep;
  31 /*
  32  * when auto defrag is enabled we
  33  * queue up these defrag structs to remember which
  34  * inodes need defragging passes
  35  */
  36 struct inode_defrag {
  37         struct rb_node rb_node;
  38         /* objectid */
  39         u64 ino;
  40         /*
  41          * transid where the defrag was added, we search for
  42          * extents newer than this
  43          */
  44         u64 transid;
  45
  46         /* root objectid */
  47         u64 root;
  48
  49         /* last offset we were able to defrag */
  50         u64 last_offset;
  51
  52         /* if we've wrapped around back to zero once already */
  53         int cycled;
  54 };
  55
  56 static int __compare_inode_defrag(struct inode_defrag *defrag1,
  57                                   struct inode_defrag *defrag2)
  58 {
  59         if (defrag1->root > defrag2->root)
  60                 return 1;
  61         else if (defrag1->root < defrag2->root)
  62                 return -1;
  63         else if (defrag1->ino > defrag2->ino)
  64                 return 1;
  65         else if (defrag1->ino < defrag2->ino)
  66                 return -1;
  67         else
  68                 return 0;
  69 }
  70
  71 /* pop a record for an inode into the defrag tree.  The lock
  72  * must be held already
  73  *
  74  * If you're inserting a record for an older transid than an
  75  * existing record, the transid already in the tree is lowered
  76  *
  77  * If an existing record is found the defrag item you
  78  * pass in is freed
  79  */
  80 static int __btrfs_add_inode_defrag(struct btrfs_inode *inode,
  81                                     struct inode_defrag *defrag)
  82 {
  83         struct btrfs_fs_info *fs_info = inode->root->fs_info;
  84         struct inode_defrag *entry;
  85         struct rb_node **p;
  86         struct rb_node *parent = NULL;
  87         int ret;
  88
  89         p = &fs_info->defrag_inodes.rb_node;
  90         while (*p) {
  91                 parent = *p;
  92                 entry = rb_entry(parent, struct inode_defrag, rb_node);
  93
  94                 ret = __compare_inode_defrag(defrag, entry);
  95                 if (ret < 0)
  96                         p = &parent->rb_left;
  97                 else if (ret > 0)
  98                         p = &parent->rb_right;
  99                 else {
 100                         /* if we're reinserting an entry for
 101                          * an old defrag run, make sure to
 102                          * lower the transid of our existing record
 103                          */
 104                         if (defrag->transid < entry->transid)
 105                                 entry->transid = defrag->transid;
 106                         if (defrag->last_offset > entry->last_offset)
 107                                 entry->last_offset = defrag->last_offset;
 108                         return -EEXIST;
 109                 }
 110         }
 111         set_bit(BTRFS_INODE_IN_DEFRAG, &inode->runtime_flags);
 112         rb_link_node(&defrag->rb_node, parent, p);
 113         rb_insert_color(&defrag->rb_node, &fs_info->defrag_inodes);
 114         return 0;
 115 }
 116
 117 static inline int __need_auto_defrag(struct btrfs_fs_info *fs_info)
 118 {
 119         if (!btrfs_test_opt(fs_info, AUTO_DEFRAG))
 120                 return 0;
 121
 122         if (btrfs_fs_closing(fs_info))
 123                 return 0;
 124
 125         return 1;
 126 }
 127
 128 /*
 129  * insert a defrag record for this inode if auto defrag is
 130  * enabled
 131  */
 132 int btrfs_add_inode_defrag(struct btrfs_trans_handle *trans,
 133                            struct btrfs_inode *inode)
 134 {
 135         struct btrfs_root *root = inode->root;
 136         struct btrfs_fs_info *fs_info = root->fs_info;
 137         struct inode_defrag *defrag;
 138         u64 transid;
 139         int ret;
 140
 141         if (!__need_auto_defrag(fs_info))
 142                 return 0;
 143
 144         if (test_bit(BTRFS_INODE_IN_DEFRAG, &inode->runtime_flags))
 145                 return 0;
 146
 147         if (trans)
 148                 transid = trans->transid;
 149         else
 150                 transid = inode->root->last_trans;
 151
 152         defrag = kmem_cache_zalloc(btrfs_inode_defrag_cachep, GFP_NOFS);
 153         if (!defrag)
 154                 return -ENOMEM;
 155
 156         defrag->ino = btrfs_ino(inode);
 157         defrag->transid = transid;
 158         defrag->root = root->root_key.objectid;
 159
 160         spin_lock(&fs_info->defrag_inodes_lock);
 161         if (!test_bit(BTRFS_INODE_IN_DEFRAG, &inode->runtime_flags)) {
 162                 /*
 163                  * If we set IN_DEFRAG flag and evict the inode from memory,
 164                  * and then re-read this inode, this new inode doesn't have
 165                  * IN_DEFRAG flag. At the case, we may find the existed defrag.
 166                  */
 167                 ret = __btrfs_add_inode_defrag(inode, defrag);
 168                 if (ret)
 169                         kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
 170         } else {
 171                 kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
 172         }
 173         spin_unlock(&fs_info->defrag_inodes_lock);
 174         return 0;
 175 }
 176
 177 /*
 178  * Requeue the defrag object. If there is a defrag object that points to
 179  * the same inode in the tree, we will merge them together (by
 180  * __btrfs_add_inode_defrag()) and free the one that we want to requeue.
 181  */
 182 static void btrfs_requeue_inode_defrag(struct btrfs_inode *inode,
 183                                        struct inode_defrag *defrag)
 184 {
 185         struct btrfs_fs_info *fs_info = inode->root->fs_info;
 186         int ret;
 187
 188         if (!__need_auto_defrag(fs_info))
 189                 goto out;
 190
 191         /*
 192          * Here we don't check the IN_DEFRAG flag, because we need merge
 193          * them together.
 194          */
 195         spin_lock(&fs_info->defrag_inodes_lock);
 196         ret = __btrfs_add_inode_defrag(inode, defrag);
 197         spin_unlock(&fs_info->defrag_inodes_lock);
 198         if (ret)
 199                 goto out;
 200         return;
 201 out:
 202         kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
 203 }
 204
 205 /*
 206  * pick the defragable inode that we want, if it doesn't exist, we will get
 207  * the next one.
 208  */
 209 static struct inode_defrag *
 210 btrfs_pick_defrag_inode(struct btrfs_fs_info *fs_info, u64 root, u64 ino)
 211 {
 212         struct inode_defrag *entry = NULL;
 213         struct inode_defrag tmp;
 214         struct rb_node *p;
 215         struct rb_node *parent = NULL;
 216         int ret;
 217
 218         tmp.ino = ino;
 219         tmp.root = root;
 220
 221         spin_lock(&fs_info->defrag_inodes_lock);
 222         p = fs_info->defrag_inodes.rb_node;
 223         while (p) {
 224                 parent = p;
 225                 entry = rb_entry(parent, struct inode_defrag, rb_node);
 226
 227                 ret = __compare_inode_defrag(&tmp, entry);
 228                 if (ret < 0)
 229                         p = parent->rb_left;
 230                 else if (ret > 0)
 231                         p = parent->rb_right;
 232                 else
 233                         goto out;
 234         }
 235
 236         if (parent && __compare_inode_defrag(&tmp, entry) > 0) {
 237                 parent = rb_next(parent);
 238                 if (parent)
 239                         entry = rb_entry(parent, struct inode_defrag, rb_node);
 240                 else
 241                         entry = NULL;
 242         }
 243 out:
 244         if (entry)
 245                 rb_erase(parent, &fs_info->defrag_inodes);
 246         spin_unlock(&fs_info->defrag_inodes_lock);
 247         return entry;
 248 }
 249
 250 void btrfs_cleanup_defrag_inodes(struct btrfs_fs_info *fs_info)
 251 {
 252         struct inode_defrag *defrag;
 253         struct rb_node *node;
 254
 255         spin_lock(&fs_info->defrag_inodes_lock);
 256         node = rb_first(&fs_info->defrag_inodes);
 257         while (node) {
 258                 rb_erase(node, &fs_info->defrag_inodes);
 259                 defrag = rb_entry(node, struct inode_defrag, rb_node);
 260                 kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
 261
 262                 cond_resched_lock(&fs_info->defrag_inodes_lock);
 263
 264                 node = rb_first(&fs_info->defrag_inodes);
 265         }
 266         spin_unlock(&fs_info->defrag_inodes_lock);
 267 }
 268
 269 #define BTRFS_DEFRAG_BATCH      1024
 270
 271 static int __btrfs_run_defrag_inode(struct btrfs_fs_info *fs_info,
 272                                     struct inode_defrag *defrag)
 273 {
 274         struct btrfs_root *inode_root;
 275         struct inode *inode;
 276         struct btrfs_key key;
 277         struct btrfs_ioctl_defrag_range_args range;
 278         int num_defrag;
 279         int index;
 280         int ret;
 281
 282         /* get the inode */
 283         key.objectid = defrag->root;
 284         key.type = BTRFS_ROOT_ITEM_KEY;
 285         key.offset = (u64)-1;
 286
 287         index = srcu_read_lock(&fs_info->subvol_srcu);
 288
 289         inode_root = btrfs_read_fs_root_no_name(fs_info, &key);
 290         if (IS_ERR(inode_root)) {
 291                 ret = PTR_ERR(inode_root);
 292                 goto cleanup;
 293         }
 294
 295         key.objectid = defrag->ino;
 296         key.type = BTRFS_INODE_ITEM_KEY;
 297         key.offset = 0;
 298         inode = btrfs_iget(fs_info->sb, &key, inode_root, NULL);
 299         if (IS_ERR(inode)) {
 300                 ret = PTR_ERR(inode);
 301                 goto cleanup;
 302         }
 303         srcu_read_unlock(&fs_info->subvol_srcu, index);
 304
 305         /* do a chunk of defrag */
 306         clear_bit(BTRFS_INODE_IN_DEFRAG, &BTRFS_I(inode)->runtime_flags);
 307         memset(&range, 0, sizeof(range));
 308         range.len = (u64)-1;
 309         range.start = defrag->last_offset;
 310
 311         sb_start_write(fs_info->sb);
 312         num_defrag = btrfs_defrag_file(inode, NULL, &range, defrag->transid,
 313                                        BTRFS_DEFRAG_BATCH);
 314         sb_end_write(fs_info->sb);
 315         /*
 316          * if we filled the whole defrag batch, there
 317          * must be more work to do.  Queue this defrag
 318          * again
 319          */
 320         if (num_defrag == BTRFS_DEFRAG_BATCH) {
 321                 defrag->last_offset = range.start;
 322                 btrfs_requeue_inode_defrag(BTRFS_I(inode), defrag);
 323         } else if (defrag->last_offset && !defrag->cycled) {
 324                 /*
 325                  * we didn't fill our defrag batch, but
 326                  * we didn't start at zero.  Make sure we loop
 327                  * around to the start of the file.
 328                  */
 329                 defrag->last_offset = 0;
 330                 defrag->cycled = 1;
 331                 btrfs_requeue_inode_defrag(BTRFS_I(inode), defrag);
 332         } else {
 333                 kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
 334         }
 335
 336         iput(inode);
 337         return 0;
 338 cleanup:
 339         srcu_read_unlock(&fs_info->subvol_srcu, index);
 340         kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
 341         return ret;
 342 }
 343
 344 /*
 345  * run through the list of inodes in the FS that need
 346  * defragging
 347  */
 348 int btrfs_run_defrag_inodes(struct btrfs_fs_info *fs_info)
 349 {
 350         struct inode_defrag *defrag;
 351         u64 first_ino = 0;
 352         u64 root_objectid = 0;
 353
 354         atomic_inc(&fs_info->defrag_running);
 355         while (1) {
 356                 /* Pause the auto defragger. */
 357                 if (test_bit(BTRFS_FS_STATE_REMOUNTING,
 358                              &fs_info->fs_state))
 359                         break;
 360
 361                 if (!__need_auto_defrag(fs_info))
 362                         break;
 363
 364                 /* find an inode to defrag */
 365                 defrag = btrfs_pick_defrag_inode(fs_info, root_objectid,
 366                                                  first_ino);
 367                 if (!defrag) {
 368                         if (root_objectid || first_ino) {
 369                                 root_objectid = 0;
 370                                 first_ino = 0;
 371                                 continue;
 372                         } else {
 373                                 break;
 374                         }
 375                 }
 376
 377                 first_ino = defrag->ino + 1;
 378                 root_objectid = defrag->root;
 379
 380                 __btrfs_run_defrag_inode(fs_info, defrag);
 381         }
 382         atomic_dec(&fs_info->defrag_running);
 383
 384         /*
 385          * during unmount, we use the transaction_wait queue to
 386          * wait for the defragger to stop
 387          */
 388         wake_up(&fs_info->transaction_wait);
 389         return 0;
 390 }
 391
 392 /* simple helper to fault in pages and copy.  This should go away
 393  * and be replaced with calls into generic code.
 394  */
 395 static noinline int btrfs_copy_from_user(loff_t pos, size_t write_bytes,
 396                                          struct page **prepared_pages,
 397                                          struct iov_iter *i)
 398 {
 399         size_t copied = 0;
 400         size_t total_copied = 0;
 401         int pg = 0;
 402         int offset = pos & (PAGE_SIZE - 1);
 403
 404         while (write_bytes > 0) {
 405                 size_t count = min_t(size_t,
 406                                      PAGE_SIZE - offset, write_bytes);
 407                 struct page *page = prepared_pages[pg];
 408                 /*
 409                  * Copy data from userspace to the current page
 410                  */
 411                 copied = iov_iter_copy_from_user_atomic(page, i, offset, count);
 412
 413                 /* Flush processor's dcache for this page */
 414                 flush_dcache_page(page);
 415
 416                 /*
 417                  * if we get a partial write, we can end up with
 418                  * partially up to date pages.  These add
 419                  * a lot of complexity, so make sure they don't
 420                  * happen by forcing this copy to be retried.
 421                  *
 422                  * The rest of the btrfs_file_write code will fall
 423                  * back to page at a time copies after we return 0.
 424                  */
 425                 if (!PageUptodate(page) && copied < count)
 426                         copied = 0;
 427
 428                 iov_iter_advance(i, copied);
 429                 write_bytes -= copied;
 430                 total_copied += copied;
 431
 432                 /* Return to btrfs_file_write_iter to fault page */
 433                 if (unlikely(copied == 0))
 434                         break;
 435
 436                 if (copied < PAGE_SIZE - offset) {
 437                         offset += copied;
 438                 } else {
 439                         pg++;
 440                         offset = 0;
 441                 }
 442         }
 443         return total_copied;
 444 }
 445
 446 /*
 447  * unlocks pages after btrfs_file_write is done with them
 448  */
 449 static void btrfs_drop_pages(struct page **pages, size_t num_pages)
 450 {
 451         size_t i;
 452         for (i = 0; i < num_pages; i++) {
 453                 /* page checked is some magic around finding pages that
 454                  * have been modified without going through btrfs_set_page_dirty
 455                  * clear it here. There should be no need to mark the pages
 456                  * accessed as prepare_pages should have marked them accessed
 457                  * in prepare_pages via find_or_create_page()
 458                  */
 459                 ClearPageChecked(pages[i]);
 460                 unlock_page(pages[i]);
 461                 put_page(pages[i]);
 462         }
 463 }
 464
 465 static int btrfs_find_new_delalloc_bytes(struct btrfs_inode *inode,
 466                                          const u64 start,
 467                                          const u64 len,
 468                                          struct extent_state **cached_state)
 469 {
 470         u64 search_start = start;
 471         const u64 end = start + len - 1;
 472
 473         while (search_start < end) {
 474                 const u64 search_len = end - search_start + 1;
 475                 struct extent_map *em;
 476                 u64 em_len;
 477                 int ret = 0;
 478
 479                 em = btrfs_get_extent(inode, NULL, 0, search_start,
 480                                       search_len, 0);
 481                 if (IS_ERR(em))
 482                         return PTR_ERR(em);
 483
 484                 if (em->block_start != EXTENT_MAP_HOLE)
 485                         goto next;
 486
 487                 em_len = em->len;
 488                 if (em->start < search_start)
 489                         em_len -= search_start - em->start;
 490                 if (em_len > search_len)
 491                         em_len = search_len;
 492
 493                 ret = set_extent_bit(&inode->io_tree, search_start,
 494                                      search_start + em_len - 1,
 495                                      EXTENT_DELALLOC_NEW,
 496                                      NULL, cached_state, GFP_NOFS);
 497 next:
 498                 search_start = extent_map_end(em);
 499                 free_extent_map(em);
 500                 if (ret)
 501                         return ret;
 502         }
 503         return 0;
 504 }
 505
 506 /*
 507  * after copy_from_user, pages need to be dirtied and we need to make
 508  * sure holes are created between the current EOF and the start of
 509  * any next extents (if required).
 510  *
 511  * this also makes the decision about creating an inline extent vs
 512  * doing real data extents, marking pages dirty and delalloc as required.
 513  */
 514 int btrfs_dirty_pages(struct inode *inode, struct page **pages,
 515                       size_t num_pages, loff_t pos, size_t write_bytes,
 516                       struct extent_state **cached)
 517 {
 518         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 519         int err = 0;
 520         int i;
 521         u64 num_bytes;
 522         u64 start_pos;
 523         u64 end_of_last_block;
 524         u64 end_pos = pos + write_bytes;
 525         loff_t isize = i_size_read(inode);
 526         unsigned int extra_bits = 0;
 527
 528         start_pos = pos & ~((u64) fs_info->sectorsize - 1);
 529         num_bytes = round_up(write_bytes + pos - start_pos,
 530                              fs_info->sectorsize);
 531
 532         end_of_last_block = start_pos + num_bytes - 1;
 533
 534         /*
 535          * The pages may have already been dirty, clear out old accounting so
 536          * we can set things up properly
 537          */
 538         clear_extent_bit(&BTRFS_I(inode)->io_tree, start_pos, end_of_last_block,
 539                          EXTENT_DIRTY | EXTENT_DELALLOC |
 540                          EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG, 0, 0, cached);
 541
 542         if (!btrfs_is_free_space_inode(BTRFS_I(inode))) {
 543                 if (start_pos >= isize &&
 544                     !(BTRFS_I(inode)->flags & BTRFS_INODE_PREALLOC)) {
 545                         /*
 546                          * There can't be any extents following eof in this case
 547                          * so just set the delalloc new bit for the range
 548                          * directly.
 549                          */
 550                         extra_bits |= EXTENT_DELALLOC_NEW;
 551                 } else {
 552                         err = btrfs_find_new_delalloc_bytes(BTRFS_I(inode),
 553                                                             start_pos,
 554                                                             num_bytes, cached);
 555                         if (err)
 556                                 return err;
 557                 }
 558         }
 559
 560         err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block,
 561                                         extra_bits, cached, 0);
 562         if (err)
 563                 return err;
 564
 565         for (i = 0; i < num_pages; i++) {
 566                 struct page *p = pages[i];
 567                 SetPageUptodate(p);
 568                 ClearPageChecked(p);
 569                 set_page_dirty(p);
 570         }
 571
 572         /*
 573          * we've only changed i_size in ram, and we haven't updated
 574          * the disk i_size.  There is no need to log the inode
 575          * at this time.
 576          */
 577         if (end_pos > isize)
 578                 i_size_write(inode, end_pos);
 579         return 0;
 580 }
 581
 582 /*
 583  * this drops all the extents in the cache that intersect the range
 584  * [start, end].  Existing extents are split as required.
 585  */
 586 void btrfs_drop_extent_cache(struct btrfs_inode *inode, u64 start, u64 end,
 587                              int skip_pinned)
 588 {
 589         struct extent_map *em;
 590         struct extent_map *split = NULL;
 591         struct extent_map *split2 = NULL;
 592         struct extent_map_tree *em_tree = &inode->extent_tree;
 593         u64 len = end - start + 1;
 594         u64 gen;
 595         int ret;
 596         int testend = 1;
 597         unsigned long flags;
 598         int compressed = 0;
 599         bool modified;
 600
 601         WARN_ON(end < start);
 602         if (end == (u64)-1) {
 603                 len = (u64)-1;
 604                 testend = 0;
 605         }
 606         while (1) {
 607                 int no_splits = 0;
 608
 609                 modified = false;
 610                 if (!split)
 611                         split = alloc_extent_map();
 612                 if (!split2)
 613                         split2 = alloc_extent_map();
 614                 if (!split || !split2)
 615                         no_splits = 1;
 616
 617                 write_lock(&em_tree->lock);
 618                 em = lookup_extent_mapping(em_tree, start, len);
 619                 if (!em) {
 620                         write_unlock(&em_tree->lock);
 621                         break;
 622                 }
 623                 flags = em->flags;
 624                 gen = em->generation;
 625                 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
 626                         if (testend && em->start + em->len >= start + len) {
 627                                 free_extent_map(em);
 628                                 write_unlock(&em_tree->lock);
 629                                 break;
 630                         }
 631                         start = em->start + em->len;
 632                         if (testend)
 633                                 len = start + len - (em->start + em->len);
 634                         free_extent_map(em);
 635                         write_unlock(&em_tree->lock);
 636                         continue;
 637                 }
 638                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 639                 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
 640                 clear_bit(EXTENT_FLAG_LOGGING, &flags);
 641                 modified = !list_empty(&em->list);
 642                 if (no_splits)
 643                         goto next;
 644
 645                 if (em->start < start) {
 646                         split->start = em->start;
 647                         split->len = start - em->start;
 648
 649                         if (em->block_start < EXTENT_MAP_LAST_BYTE) {
 650                                 split->orig_start = em->orig_start;
 651                                 split->block_start = em->block_start;
 652
 653                                 if (compressed)
 654                                         split->block_len = em->block_len;
 655                                 else
 656                                         split->block_len = split->len;
 657                                 split->orig_block_len = max(split->block_len,
 658                                                 em->orig_block_len);
 659                                 split->ram_bytes = em->ram_bytes;
 660                         } else {
 661                                 split->orig_start = split->start;
 662                                 split->block_len = 0;
 663                                 split->block_start = em->block_start;
 664                                 split->orig_block_len = 0;
 665                                 split->ram_bytes = split->len;
 666                         }
 667
 668                         split->generation = gen;
 669                         split->bdev = em->bdev;
 670                         split->flags = flags;
 671                         split->compress_type = em->compress_type;
 672                         replace_extent_mapping(em_tree, em, split, modified);
 673                         free_extent_map(split);
 674                         split = split2;
 675                         split2 = NULL;
 676                 }
 677                 if (testend && em->start + em->len > start + len) {
 678                         u64 diff = start + len - em->start;
 679
 680                         split->start = start + len;
 681                         split->len = em->start + em->len - (start + len);
 682                         split->bdev = em->bdev;
 683                         split->flags = flags;
 684                         split->compress_type = em->compress_type;
 685                         split->generation = gen;
 686
 687                         if (em->block_start < EXTENT_MAP_LAST_BYTE) {
 688                                 split->orig_block_len = max(em->block_len,
 689                                                     em->orig_block_len);
 690
 691                                 split->ram_bytes = em->ram_bytes;
 692                                 if (compressed) {
 693                                         split->block_len = em->block_len;
 694                                         split->block_start = em->block_start;
 695                                         split->orig_start = em->orig_start;
 696                                 } else {
 697                                         split->block_len = split->len;
 698                                         split->block_start = em->block_start
 699                                                 + diff;
 700                                         split->orig_start = em->orig_start;
 701                                 }
 702                         } else {
 703                                 split->ram_bytes = split->len;
 704                                 split->orig_start = split->start;
 705                                 split->block_len = 0;
 706                                 split->block_start = em->block_start;
 707                                 split->orig_block_len = 0;
 708                         }
 709
 710                         if (extent_map_in_tree(em)) {
 711                                 replace_extent_mapping(em_tree, em, split,
 712                                                        modified);
 713                         } else {
 714                                 ret = add_extent_mapping(em_tree, split,
 715                                                          modified);
 716                                 ASSERT(ret == 0); /* Logic error */
 717                         }
 718                         free_extent_map(split);
 719                         split = NULL;
 720                 }
 721 next:
 722                 if (extent_map_in_tree(em))
 723                         remove_extent_mapping(em_tree, em);
 724                 write_unlock(&em_tree->lock);
 725
 726                 /* once for us */
 727                 free_extent_map(em);
 728                 /* once for the tree*/
 729                 free_extent_map(em);
 730         }
 731         if (split)
 732                 free_extent_map(split);
 733         if (split2)
 734                 free_extent_map(split2);
 735 }
 736
 737 /*
 738  * this is very complex, but the basic idea is to drop all extents
 739  * in the range start - end.  hint_block is filled in with a block number
 740  * that would be a good hint to the block allocator for this file.
 741  *
 742  * If an extent intersects the range but is not entirely inside the range
 743  * it is either truncated or split.  Anything entirely inside the range
 744  * is deleted from the tree.
 745  */
 746 int __btrfs_drop_extents(struct btrfs_trans_handle *trans,
 747                          struct btrfs_root *root, struct inode *inode,
 748                          struct btrfs_path *path, u64 start, u64 end,
 749                          u64 *drop_end, int drop_cache,
 750                          int replace_extent,
 751                          u32 extent_item_size,
 752                          int *key_inserted)
 753 {
 754         struct btrfs_fs_info *fs_info = root->fs_info;
 755         struct extent_buffer *leaf;
 756         struct btrfs_file_extent_item *fi;
 757         struct btrfs_key key;
 758         struct btrfs_key new_key;
 759         u64 ino = btrfs_ino(BTRFS_I(inode));
 760         u64 search_start = start;
 761         u64 disk_bytenr = 0;
 762         u64 num_bytes = 0;
 763         u64 extent_offset = 0;
 764         u64 extent_end = 0;
 765         u64 last_end = start;
 766         int del_nr = 0;
 767         int del_slot = 0;
 768         int extent_type;
 769         int recow;
 770         int ret;
 771         int modify_tree = -1;
 772         int update_refs;
 773         int found = 0;
 774         int leafs_visited = 0;
 775
 776         if (drop_cache)
 777                 btrfs_drop_extent_cache(BTRFS_I(inode), start, end - 1, 0);
 778
 779         if (start >= BTRFS_I(inode)->disk_i_size && !replace_extent)
 780                 modify_tree = 0;
 781
 782         update_refs = (test_bit(BTRFS_ROOT_REF_COWS, &root->state) ||
 783                        root == fs_info->tree_root);
 784         while (1) {
 785                 recow = 0;
 786                 ret = btrfs_lookup_file_extent(trans, root, path, ino,
 787                                                search_start, modify_tree);
 788                 if (ret < 0)
 789                         break;
 790                 if (ret > 0 && path->slots[0] > 0 && search_start == start) {
 791                         leaf = path->nodes[0];
 792                         btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 793                         if (key.objectid == ino &&
 794                             key.type == BTRFS_EXTENT_DATA_KEY)
 795                                 path->slots[0]--;
 796                 }
 797                 ret = 0;
 798                 leafs_visited++;
 799 next_slot:
 800                 leaf = path->nodes[0];
 801                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 802                         BUG_ON(del_nr > 0);
 803                         ret = btrfs_next_leaf(root, path);
 804                         if (ret < 0)
 805                                 break;
 806                         if (ret > 0) {
 807                                 ret = 0;
 808                                 break;
 809                         }
 810                         leafs_visited++;
 811                         leaf = path->nodes[0];
 812                         recow = 1;
 813                 }
 814
 815                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 816
 817                 if (key.objectid > ino)
 818                         break;
 819                 if (WARN_ON_ONCE(key.objectid < ino) ||
 820                     key.type < BTRFS_EXTENT_DATA_KEY) {
 821                         ASSERT(del_nr == 0);
 822                         path->slots[0]++;
 823                         goto next_slot;
 824                 }
 825                 if (key.type > BTRFS_EXTENT_DATA_KEY || key.offset >= end)
 826                         break;
 827
 828                 fi = btrfs_item_ptr(leaf, path->slots[0],
 829                                     struct btrfs_file_extent_item);
 830                 extent_type = btrfs_file_extent_type(leaf, fi);
 831
 832                 if (extent_type == BTRFS_FILE_EXTENT_REG ||
 833                     extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
 834                         disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 835                         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
 836                         extent_offset = btrfs_file_extent_offset(leaf, fi);
 837                         extent_end = key.offset +
 838                                 btrfs_file_extent_num_bytes(leaf, fi);
 839                 } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 840                         extent_end = key.offset +
 841                                 btrfs_file_extent_ram_bytes(leaf, fi);
 842                 } else {
 843                         /* can't happen */
 844                         BUG();
 845                 }
 846
 847                 /*
 848                  * Don't skip extent items representing 0 byte lengths. They
 849                  * used to be created (bug) if while punching holes we hit
 850                  * -ENOSPC condition. So if we find one here, just ensure we
 851                  * delete it, otherwise we would insert a new file extent item
 852                  * with the same key (offset) as that 0 bytes length file
 853                  * extent item in the call to setup_items_for_insert() later
 854                  * in this function.
 855                  */
 856                 if (extent_end == key.offset && extent_end >= search_start) {
 857                         last_end = extent_end;
 858                         goto delete_extent_item;
 859                 }
 860
 861                 if (extent_end <= search_start) {
 862                         path->slots[0]++;
 863                         goto next_slot;
 864                 }
 865
 866                 found = 1;
 867                 search_start = max(key.offset, start);
 868                 if (recow || !modify_tree) {
 869                         modify_tree = -1;
 870                         btrfs_release_path(path);
 871                         continue;
 872                 }
 873
 874                 /*
 875                  *     | - range to drop - |
 876                  *  | -------- extent -------- |
 877                  */
 878                 if (start > key.offset && end < extent_end) {
 879                         BUG_ON(del_nr > 0);
 880                         if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 881                                 ret = -EOPNOTSUPP;
 882                                 break;
 883                         }
 884
 885                         memcpy(&new_key, &key, sizeof(new_key));
 886                         new_key.offset = start;
 887                         ret = btrfs_duplicate_item(trans, root, path,
 888                                                    &new_key);
 889                         if (ret == -EAGAIN) {
 890                                 btrfs_release_path(path);
 891                                 continue;
 892                         }
 893                         if (ret < 0)
 894                                 break;
 895
 896                         leaf = path->nodes[0];
 897                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
 898                                             struct btrfs_file_extent_item);
 899                         btrfs_set_file_extent_num_bytes(leaf, fi,
 900                                                         start - key.offset);
 901
 902                         fi = btrfs_item_ptr(leaf, path->slots[0],
 903                                             struct btrfs_file_extent_item);
 904
 905                         extent_offset += start - key.offset;
 906                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
 907                         btrfs_set_file_extent_num_bytes(leaf, fi,
 908                                                         extent_end - start);
 909                         btrfs_mark_buffer_dirty(leaf);
 910
 911                         if (update_refs && disk_bytenr > 0) {
 912                                 ret = btrfs_inc_extent_ref(trans, root,
 913                                                 disk_bytenr, num_bytes, 0,
 914                                                 root->root_key.objectid,
 915                                                 new_key.objectid,
 916                                                 start - extent_offset);
 917                                 BUG_ON(ret); /* -ENOMEM */
 918                         }
 919                         key.offset = start;
 920                 }
 921                 /*
 922                  * From here on out we will have actually dropped something, so
 923                  * last_end can be updated.
 924                  */
 925                 last_end = extent_end;
 926
 927                 /*
 928                  *  | ---- range to drop ----- |
 929                  *      | -------- extent -------- |
 930                  */
 931                 if (start <= key.offset && end < extent_end) {
 932                         if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 933                                 ret = -EOPNOTSUPP;
 934                                 break;
 935                         }
 936
 937                         memcpy(&new_key, &key, sizeof(new_key));
 938                         new_key.offset = end;
 939                         btrfs_set_item_key_safe(fs_info, path, &new_key);
 940
 941                         extent_offset += end - key.offset;
 942                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
 943                         btrfs_set_file_extent_num_bytes(leaf, fi,
 944                                                         extent_end - end);
 945                         btrfs_mark_buffer_dirty(leaf);
 946                         if (update_refs && disk_bytenr > 0)
 947                                 inode_sub_bytes(inode, end - key.offset);
 948                         break;
 949                 }
 950
 951                 search_start = extent_end;
 952                 /*
 953                  *       | ---- range to drop ----- |
 954                  *  | -------- extent -------- |
 955                  */
 956                 if (start > key.offset && end >= extent_end) {
 957                         BUG_ON(del_nr > 0);
 958                         if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 959                                 ret = -EOPNOTSUPP;
 960                                 break;
 961                         }
 962
 963                         btrfs_set_file_extent_num_bytes(leaf, fi,
 964                                                         start - key.offset);
 965                         btrfs_mark_buffer_dirty(leaf);
 966                         if (update_refs && disk_bytenr > 0)
 967                                 inode_sub_bytes(inode, extent_end - start);
 968                         if (end == extent_end)
 969                                 break;
 970
 971                         path->slots[0]++;
 972                         goto next_slot;
 973                 }
 974
 975                 /*
 976                  *  | ---- range to drop ----- |
 977                  *    | ------ extent ------ |
 978                  */
 979                 if (start <= key.offset && end >= extent_end) {
 980 delete_extent_item:
 981                         if (del_nr == 0) {
 982                                 del_slot = path->slots[0];
 983                                 del_nr = 1;
 984                         } else {
 985                                 BUG_ON(del_slot + del_nr != path->slots[0]);
 986                                 del_nr++;
 987                         }
 988
 989                         if (update_refs &&
 990                             extent_type == BTRFS_FILE_EXTENT_INLINE) {
 991                                 inode_sub_bytes(inode,
 992                                                 extent_end - key.offset);
 993                                 extent_end = ALIGN(extent_end,
 994                                                    fs_info->sectorsize);
 995                         } else if (update_refs && disk_bytenr > 0) {
 996                                 ret = btrfs_free_extent(trans, root,
 997                                                 disk_bytenr, num_bytes, 0,
 998                                                 root->root_key.objectid,
 999                                                 key.objectid, key.offset -
1000                                                 extent_offset);
1001                                 BUG_ON(ret); /* -ENOMEM */
1002                                 inode_sub_bytes(inode,
1003                                                 extent_end - key.offset);
1004                         }
1005
1006                         if (end == extent_end)
1007                                 break;
1008
1009                         if (path->slots[0] + 1 < btrfs_header_nritems(leaf)) {
1010                                 path->slots[0]++;
1011                                 goto next_slot;
1012                         }
1013
1014                         ret = btrfs_del_items(trans, root, path, del_slot,
1015                                               del_nr);
1016                         if (ret) {
1017                                 btrfs_abort_transaction(trans, ret);
1018                                 break;
1019                         }
1020
1021                         del_nr = 0;
1022                         del_slot = 0;
1023
1024                         btrfs_release_path(path);
1025                         continue;
1026                 }
1027
1028                 BUG_ON(1);
1029         }
1030
1031         if (!ret && del_nr > 0) {
1032                 /*
1033                  * Set path->slots[0] to first slot, so that after the delete
1034                  * if items are move off from our leaf to its immediate left or
1035                  * right neighbor leafs, we end up with a correct and adjusted
1036                  * path->slots[0] for our insertion (if replace_extent != 0).
1037                  */
1038                 path->slots[0] = del_slot;
1039                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
1040                 if (ret)
1041                         btrfs_abort_transaction(trans, ret);
1042         }
1043
1044         leaf = path->nodes[0];
1045         /*
1046          * If btrfs_del_items() was called, it might have deleted a leaf, in
1047          * which case it unlocked our path, so check path->locks[0] matches a
1048          * write lock.
1049          */
1050         if (!ret && replace_extent && leafs_visited == 1 &&
1051             (path->locks[0] == BTRFS_WRITE_LOCK_BLOCKING ||
1052              path->locks[0] == BTRFS_WRITE_LOCK) &&
1053             btrfs_leaf_free_space(fs_info, leaf) >=
1054             sizeof(struct btrfs_item) + extent_item_size) {
1055
1056                 key.objectid = ino;
1057                 key.type = BTRFS_EXTENT_DATA_KEY;
1058                 key.offset = start;
1059                 if (!del_nr && path->slots[0] < btrfs_header_nritems(leaf)) {
1060                         struct btrfs_key slot_key;
1061
1062                         btrfs_item_key_to_cpu(leaf, &slot_key, path->slots[0]);
1063                         if (btrfs_comp_cpu_keys(&key, &slot_key) > 0)
1064                                 path->slots[0]++;
1065                 }
1066                 setup_items_for_insert(root, path, &key,
1067                                        &extent_item_size,
1068                                        extent_item_size,
1069                                        sizeof(struct btrfs_item) +
1070                                        extent_item_size, 1);
1071                 *key_inserted = 1;
1072         }
1073
1074         if (!replace_extent || !(*key_inserted))
1075                 btrfs_release_path(path);
1076         if (drop_end)
1077                 *drop_end = found ? min(end, last_end) : end;
1078         return ret;
1079 }
1080
1081 int btrfs_drop_extents(struct btrfs_trans_handle *trans,
1082                        struct btrfs_root *root, struct inode *inode, u64 start,
1083                        u64 end, int drop_cache)
1084 {
1085         struct btrfs_path *path;
1086         int ret;
1087
1088         path = btrfs_alloc_path();
1089         if (!path)
1090                 return -ENOMEM;
1091         ret = __btrfs_drop_extents(trans, root, inode, path, start, end, NULL,
1092                                    drop_cache, 0, 0, NULL);
1093         btrfs_free_path(path);
1094         return ret;
1095 }
1096
1097 static int extent_mergeable(struct extent_buffer *leaf, int slot,
1098                             u64 objectid, u64 bytenr, u64 orig_offset,
1099                             u64 *start, u64 *end)
1100 {
1101         struct btrfs_file_extent_item *fi;
1102         struct btrfs_key key;
1103         u64 extent_end;
1104
1105         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
1106                 return 0;
1107
1108         btrfs_item_key_to_cpu(leaf, &key, slot);
1109         if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
1110                 return 0;
1111
1112         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
1113         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
1114             btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
1115             btrfs_file_extent_offset(leaf, fi) != key.offset - orig_offset ||
1116             btrfs_file_extent_compression(leaf, fi) ||
1117             btrfs_file_extent_encryption(leaf, fi) ||
1118             btrfs_file_extent_other_encoding(leaf, fi))
1119                 return 0;
1120
1121         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
1122         if ((*start && *start != key.offset) || (*end && *end != extent_end))
1123                 return 0;
1124
1125         *start = key.offset;
1126         *end = extent_end;
1127         return 1;
1128 }
1129
1130 /*
1131  * Mark extent in the range start - end as written.
1132  *
1133  * This changes extent type from 'pre-allocated' to 'regular'. If only
1134  * part of extent is marked as written, the extent will be split into
1135  * two or three.
1136  */
1137 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
1138                               struct btrfs_inode *inode, u64 start, u64 end)
1139 {
1140         struct btrfs_fs_info *fs_info = trans->fs_info;
1141         struct btrfs_root *root = inode->root;
1142         struct extent_buffer *leaf;
1143         struct btrfs_path *path;
1144         struct btrfs_file_extent_item *fi;
1145         struct btrfs_key key;
1146         struct btrfs_key new_key;
1147         u64 bytenr;
1148         u64 num_bytes;
1149         u64 extent_end;
1150         u64 orig_offset;
1151         u64 other_start;
1152         u64 other_end;
1153         u64 split;
1154         int del_nr = 0;
1155         int del_slot = 0;
1156         int recow;
1157         int ret;
1158         u64 ino = btrfs_ino(inode);
1159
1160         path = btrfs_alloc_path();
1161         if (!path)
1162                 return -ENOMEM;
1163 again:
1164         recow = 0;
1165         split = start;
1166         key.objectid = ino;
1167         key.type = BTRFS_EXTENT_DATA_KEY;
1168         key.offset = split;
1169
1170         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
1171         if (ret < 0)
1172                 goto out;
1173         if (ret > 0 && path->slots[0] > 0)
1174                 path->slots[0]--;
1175
1176         leaf = path->nodes[0];
1177         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
1178         if (key.objectid != ino ||
1179             key.type != BTRFS_EXTENT_DATA_KEY) {
1180                 ret = -EINVAL;
1181                 btrfs_abort_transaction(trans, ret);
1182                 goto out;
1183         }
1184         fi = btrfs_item_ptr(leaf, path->slots[0],
1185                             struct btrfs_file_extent_item);
1186         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_PREALLOC) {
1187                 ret = -EINVAL;
1188                 btrfs_abort_transaction(trans, ret);
1189                 goto out;
1190         }
1191         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
1192         if (key.offset > start || extent_end < end) {
1193                 ret = -EINVAL;
1194                 btrfs_abort_transaction(trans, ret);
1195                 goto out;
1196         }
1197
1198         bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1199         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1200         orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
1201         memcpy(&new_key, &key, sizeof(new_key));
1202
1203         if (start == key.offset && end < extent_end) {
1204                 other_start = 0;
1205                 other_end = start;
1206                 if (extent_mergeable(leaf, path->slots[0] - 1,
1207                                      ino, bytenr, orig_offset,
1208                                      &other_start, &other_end)) {
1209                         new_key.offset = end;
1210                         btrfs_set_item_key_safe(fs_info, path, &new_key);
1211                         fi = btrfs_item_ptr(leaf, path->slots[0],
1212                                             struct btrfs_file_extent_item);
1213                         btrfs_set_file_extent_generation(leaf, fi,
1214                                                          trans->transid);
1215                         btrfs_set_file_extent_num_bytes(leaf, fi,
1216                                                         extent_end - end);
1217                         btrfs_set_file_extent_offset(leaf, fi,
1218                                                      end - orig_offset);
1219                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
1220                                             struct btrfs_file_extent_item);
1221                         btrfs_set_file_extent_generation(leaf, fi,
1222                                                          trans->transid);
1223                         btrfs_set_file_extent_num_bytes(leaf, fi,
1224                                                         end - other_start);
1225                         btrfs_mark_buffer_dirty(leaf);
1226                         goto out;
1227                 }
1228         }
1229
1230         if (start > key.offset && end == extent_end) {
1231                 other_start = end;
1232                 other_end = 0;
1233                 if (extent_mergeable(leaf, path->slots[0] + 1,
1234                                      ino, bytenr, orig_offset,
1235                                      &other_start, &other_end)) {
1236                         fi = btrfs_item_ptr(leaf, path->slots[0],
1237                                             struct btrfs_file_extent_item);
1238                         btrfs_set_file_extent_num_bytes(leaf, fi,
1239                                                         start - key.offset);
1240                         btrfs_set_file_extent_generation(leaf, fi,
1241                                                          trans->transid);
1242                         path->slots[0]++;
1243                         new_key.offset = start;
1244                         btrfs_set_item_key_safe(fs_info, path, &new_key);
1245
1246                         fi = btrfs_item_ptr(leaf, path->slots[0],
1247                                             struct btrfs_file_extent_item);
1248                         btrfs_set_file_extent_generation(leaf, fi,
1249                                                          trans->transid);
1250                         btrfs_set_file_extent_num_bytes(leaf, fi,
1251                                                         other_end - start);
1252                         btrfs_set_file_extent_offset(leaf, fi,
1253                                                      start - orig_offset);
1254                         btrfs_mark_buffer_dirty(leaf);
1255                         goto out;
1256                 }
1257         }
1258
1259         while (start > key.offset || end < extent_end) {
1260                 if (key.offset == start)
1261                         split = end;
1262
1263                 new_key.offset = split;
1264                 ret = btrfs_duplicate_item(trans, root, path, &new_key);
1265                 if (ret == -EAGAIN) {
1266                         btrfs_release_path(path);
1267                         goto again;
1268                 }
1269                 if (ret < 0) {
1270                         btrfs_abort_transaction(trans, ret);
1271                         goto out;
1272                 }
1273
1274                 leaf = path->nodes[0];
1275                 fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
1276                                     struct btrfs_file_extent_item);
1277                 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
1278                 btrfs_set_file_extent_num_bytes(leaf, fi,
1279                                                 split - key.offset);
1280
1281                 fi = btrfs_item_ptr(leaf, path->slots[0],
1282                                     struct btrfs_file_extent_item);
1283
1284                 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
1285                 btrfs_set_file_extent_offset(leaf, fi, split - orig_offset);
1286                 btrfs_set_file_extent_num_bytes(leaf, fi,
1287                                                 extent_end - split);
1288                 btrfs_mark_buffer_dirty(leaf);
1289
1290                 ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes,
1291                                            0, root->root_key.objectid,
1292                                            ino, orig_offset);
1293                 if (ret) {
1294                         btrfs_abort_transaction(trans, ret);
1295                         goto out;
1296                 }
1297
1298                 if (split == start) {
1299                         key.offset = start;
1300                 } else {
1301                         if (start != key.offset) {
1302                                 ret = -EINVAL;
1303                                 btrfs_abort_transaction(trans, ret);
1304                                 goto out;
1305                         }
1306                         path->slots[0]--;
1307                         extent_end = end;
1308                 }
1309                 recow = 1;
1310         }
1311
1312         other_start = end;
1313         other_end = 0;
1314         if (extent_mergeable(leaf, path->slots[0] + 1,
1315                              ino, bytenr, orig_offset,
1316                              &other_start, &other_end)) {
1317                 if (recow) {
1318                         btrfs_release_path(path);
1319                         goto again;
1320                 }
1321                 extent_end = other_end;
1322                 del_slot = path->slots[0] + 1;
1323                 del_nr++;
1324                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1325                                         0, root->root_key.objectid,
1326                                         ino, orig_offset);
1327                 if (ret) {
1328                         btrfs_abort_transaction(trans, ret);
1329                         goto out;
1330                 }
1331         }
1332         other_start = 0;
1333         other_end = start;
1334         if (extent_mergeable(leaf, path->slots[0] - 1,
1335                              ino, bytenr, orig_offset,
1336                              &other_start, &other_end)) {
1337                 if (recow) {
1338                         btrfs_release_path(path);
1339                         goto again;
1340                 }
1341                 key.offset = other_start;
1342                 del_slot = path->slots[0];
1343                 del_nr++;
1344                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1345                                         0, root->root_key.objectid,
1346                                         ino, orig_offset);
1347                 if (ret) {
1348                         btrfs_abort_transaction(trans, ret);
1349                         goto out;
1350                 }
1351         }
1352         if (del_nr == 0) {
1353                 fi = btrfs_item_ptr(leaf, path->slots[0],
1354                            struct btrfs_file_extent_item);
1355                 btrfs_set_file_extent_type(leaf, fi,
1356                                            BTRFS_FILE_EXTENT_REG);
1357                 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
1358                 btrfs_mark_buffer_dirty(leaf);
1359         } else {
1360                 fi = btrfs_item_ptr(leaf, del_slot - 1,
1361                            struct btrfs_file_extent_item);
1362                 btrfs_set_file_extent_type(leaf, fi,
1363                                            BTRFS_FILE_EXTENT_REG);
1364                 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
1365                 btrfs_set_file_extent_num_bytes(leaf, fi,
1366                                                 extent_end - key.offset);
1367                 btrfs_mark_buffer_dirty(leaf);
1368
1369                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
1370                 if (ret < 0) {
1371                         btrfs_abort_transaction(trans, ret);
1372                         goto out;
1373                 }
1374         }
1375 out:
1376         btrfs_free_path(path);
1377         return 0;
1378 }
1379
1380 /*
1381  * on error we return an unlocked page and the error value
1382  * on success we return a locked page and 0
1383  */
1384 static int prepare_uptodate_page(struct inode *inode,
1385                                  struct page *page, u64 pos,
1386                                  bool force_uptodate)
1387 {
1388         int ret = 0;
1389
1390         if (((pos & (PAGE_SIZE - 1)) || force_uptodate) &&
1391             !PageUptodate(page)) {
1392                 ret = btrfs_readpage(NULL, page);
1393                 if (ret)
1394                         return ret;
1395                 lock_page(page);
1396                 if (!PageUptodate(page)) {
1397                         unlock_page(page);
1398                         return -EIO;
1399                 }
1400                 if (page->mapping != inode->i_mapping) {
1401                         unlock_page(page);
1402                         return -EAGAIN;
1403                 }
1404         }
1405         return 0;
1406 }
1407
1408 /*
1409  * this just gets pages into the page cache and locks them down.
1410  */
1411 static noinline int prepare_pages(struct inode *inode, struct page **pages,
1412                                   size_t num_pages, loff_t pos,
1413                                   size_t write_bytes, bool force_uptodate)
1414 {
1415         int i;
1416         unsigned long index = pos >> PAGE_SHIFT;
1417         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
1418         int err = 0;
1419         int faili;
1420
1421         for (i = 0; i < num_pages; i++) {
1422 again:
1423                 pages[i] = find_or_create_page(inode->i_mapping, index + i,
1424                                                mask | __GFP_WRITE);
1425                 if (!pages[i]) {
1426                         faili = i - 1;
1427                         err = -ENOMEM;
1428                         goto fail;
1429                 }
1430
1431                 if (i == 0)
1432                         err = prepare_uptodate_page(inode, pages[i], pos,
1433                                                     force_uptodate);
1434                 if (!err && i == num_pages - 1)
1435                         err = prepare_uptodate_page(inode, pages[i],
1436                                                     pos + write_bytes, false);
1437                 if (err) {
1438                         put_page(pages[i]);
1439                         if (err == -EAGAIN) {
1440                                 err = 0;
1441                                 goto again;
1442                         }
1443                         faili = i - 1;
1444                         goto fail;
1445                 }
1446                 wait_on_page_writeback(pages[i]);
1447         }
1448
1449         return 0;
1450 fail:
1451         while (faili >= 0) {
1452                 unlock_page(pages[faili]);
1453                 put_page(pages[faili]);
1454                 faili--;
1455         }
1456         return err;
1457
1458 }
1459
1460 /*
1461  * This function locks the extent and properly waits for data=ordered extents
1462  * to finish before allowing the pages to be modified if need.
1463  *
1464  * The return value:
1465  * 1 - the extent is locked
1466  * 0 - the extent is not locked, and everything is OK
1467  * -EAGAIN - need re-prepare the pages
1468  * the other < 0 number - Something wrong happens
1469  */
1470 static noinline int
1471 lock_and_cleanup_extent_if_need(struct btrfs_inode *inode, struct page **pages,
1472                                 size_t num_pages, loff_t pos,
1473                                 size_t write_bytes,
1474                                 u64 *lockstart, u64 *lockend,
1475                                 struct extent_state **cached_state)
1476 {
1477         struct btrfs_fs_info *fs_info = inode->root->fs_info;
1478         u64 start_pos;
1479         u64 last_pos;
1480         int i;
1481         int ret = 0;
1482
1483         start_pos = round_down(pos, fs_info->sectorsize);
1484         last_pos = start_pos
1485                 + round_up(pos + write_bytes - start_pos,
1486                            fs_info->sectorsize) - 1;
1487
1488         if (start_pos < inode->vfs_inode.i_size) {
1489                 struct btrfs_ordered_extent *ordered;
1490
1491                 lock_extent_bits(&inode->io_tree, start_pos, last_pos,
1492                                 cached_state);
1493                 ordered = btrfs_lookup_ordered_range(inode, start_pos,
1494                                                      last_pos - start_pos + 1);
1495                 if (ordered &&
1496                     ordered->file_offset + ordered->len > start_pos &&
1497                     ordered->file_offset <= last_pos) {
1498                         unlock_extent_cached(&inode->io_tree, start_pos,
1499                                         last_pos, cached_state);
1500                         for (i = 0; i < num_pages; i++) {
1501                                 unlock_page(pages[i]);
1502                                 put_page(pages[i]);
1503                         }
1504                         btrfs_start_ordered_extent(&inode->vfs_inode,
1505                                         ordered, 1);
1506                         btrfs_put_ordered_extent(ordered);
1507                         return -EAGAIN;
1508                 }
1509                 if (ordered)
1510                         btrfs_put_ordered_extent(ordered);
1511
1512                 *lockstart = start_pos;
1513                 *lockend = last_pos;
1514                 ret = 1;
1515         }
1516
1517         /*
1518          * It's possible the pages are dirty right now, but we don't want
1519          * to clean them yet because copy_from_user may catch a page fault
1520          * and we might have to fall back to one page at a time.  If that
1521          * happens, we'll unlock these pages and we'd have a window where
1522          * reclaim could sneak in and drop the once-dirty page on the floor
1523          * without writing it.
1524          *
1525          * We have the pages locked and the extent range locked, so there's
1526          * no way someone can start IO on any dirty pages in this range.
1527          *
1528          * We'll call btrfs_dirty_pages() later on, and that will flip around
1529          * delalloc bits and dirty the pages as required.
1530          */
1531         for (i = 0; i < num_pages; i++) {
1532                 set_page_extent_mapped(pages[i]);
1533                 WARN_ON(!PageLocked(pages[i]));
1534         }
1535
1536         return ret;
1537 }
1538
1539 static noinline int check_can_nocow(struct btrfs_inode *inode, loff_t pos,
1540                                     size_t *write_bytes)
1541 {
1542         struct btrfs_fs_info *fs_info = inode->root->fs_info;
1543         struct btrfs_root *root = inode->root;
1544         struct btrfs_ordered_extent *ordered;
1545         u64 lockstart, lockend;
1546         u64 num_bytes;
1547         int ret;
1548
1549         ret = btrfs_start_write_no_snapshotting(root);
1550         if (!ret)
1551                 return -ENOSPC;
1552
1553         lockstart = round_down(pos, fs_info->sectorsize);
1554         lockend = round_up(pos + *write_bytes,
1555                            fs_info->sectorsize) - 1;
1556
1557         while (1) {
1558                 lock_extent(&inode->io_tree, lockstart, lockend);
1559                 ordered = btrfs_lookup_ordered_range(inode, lockstart,
1560                                                      lockend - lockstart + 1);
1561                 if (!ordered) {
1562                         break;
1563                 }
1564                 unlock_extent(&inode->io_tree, lockstart, lockend);
1565                 btrfs_start_ordered_extent(&inode->vfs_inode, ordered, 1);
1566                 btrfs_put_ordered_extent(ordered);
1567         }
1568
1569         num_bytes = lockend - lockstart + 1;
1570         ret = can_nocow_extent(&inode->vfs_inode, lockstart, &num_bytes,
1571                         NULL, NULL, NULL);
1572         if (ret <= 0) {
1573                 ret = 0;
1574                 btrfs_end_write_no_snapshotting(root);
1575         } else {
1576                 *write_bytes = min_t(size_t, *write_bytes ,
1577                                      num_bytes - pos + lockstart);
1578         }
1579
1580         unlock_extent(&inode->io_tree, lockstart, lockend);
1581
1582         return ret;
1583 }
1584
1585 static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb,
1586                                                struct iov_iter *i)
1587 {
1588         struct file *file = iocb->ki_filp;
1589         loff_t pos = iocb->ki_pos;
1590         struct inode *inode = file_inode(file);
1591         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
1592         struct btrfs_root *root = BTRFS_I(inode)->root;
1593         struct page **pages = NULL;
1594         struct extent_state *cached_state = NULL;
1595         struct extent_changeset *data_reserved = NULL;
1596         u64 release_bytes = 0;
1597         u64 lockstart;
1598         u64 lockend;
1599         size_t num_written = 0;
1600         int nrptrs;
1601         int ret = 0;
1602         bool only_release_metadata = false;
1603         bool force_page_uptodate = false;
1604
1605         nrptrs = min(DIV_ROUND_UP(iov_iter_count(i), PAGE_SIZE),
1606                         PAGE_SIZE / (sizeof(struct page *)));
1607         nrptrs = min(nrptrs, current->nr_dirtied_pause - current->nr_dirtied);
1608         nrptrs = max(nrptrs, 8);
1609         pages = kmalloc_array(nrptrs, sizeof(struct page *), GFP_KERNEL);
1610         if (!pages)
1611                 return -ENOMEM;
1612
1613         while (iov_iter_count(i) > 0) {
1614                 size_t offset = pos & (PAGE_SIZE - 1);
1615                 size_t sector_offset;
1616                 size_t write_bytes = min(iov_iter_count(i),
1617                                          nrptrs * (size_t)PAGE_SIZE -
1618                                          offset);
1619                 size_t num_pages = DIV_ROUND_UP(write_bytes + offset,
1620                                                 PAGE_SIZE);
1621                 size_t reserve_bytes;
1622                 size_t dirty_pages;
1623                 size_t copied;
1624                 size_t dirty_sectors;
1625                 size_t num_sectors;
1626                 int extents_locked;
1627
1628                 WARN_ON(num_pages > nrptrs);
1629
1630                 /*
1631                  * Fault pages before locking them in prepare_pages
1632                  * to avoid recursive lock
1633                  */
1634                 if (unlikely(iov_iter_fault_in_readable(i, write_bytes))) {
1635                         ret = -EFAULT;
1636                         break;
1637                 }
1638
1639                 sector_offset = pos & (fs_info->sectorsize - 1);
1640                 reserve_bytes = round_up(write_bytes + sector_offset,
1641                                 fs_info->sectorsize);
1642
1643                 extent_changeset_release(data_reserved);
1644                 ret = btrfs_check_data_free_space(inode, &data_reserved, pos,
1645                                                   write_bytes);
1646                 if (ret < 0) {
1647                         if ((BTRFS_I(inode)->flags & (BTRFS_INODE_NODATACOW |
1648                                                       BTRFS_INODE_PREALLOC)) &&
1649                             check_can_nocow(BTRFS_I(inode), pos,
1650                                         &write_bytes) > 0) {
1651                                 /*
1652                                  * For nodata cow case, no need to reserve
1653                                  * data space.
1654                                  */
1655                                 only_release_metadata = true;
1656                                 /*
1657                                  * our prealloc extent may be smaller than
1658                                  * write_bytes, so scale down.
1659                                  */
1660                                 num_pages = DIV_ROUND_UP(write_bytes + offset,
1661                                                          PAGE_SIZE);
1662                                 reserve_bytes = round_up(write_bytes +
1663                                                          sector_offset,
1664                                                          fs_info->sectorsize);
1665                         } else {
1666                                 break;
1667                         }
1668                 }
1669
1670                 WARN_ON(reserve_bytes == 0);
1671                 ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode),
1672                                 reserve_bytes);
1673                 if (ret) {
1674                         if (!only_release_metadata)
1675                                 btrfs_free_reserved_data_space(inode,
1676                                                 data_reserved, pos,
1677                                                 write_bytes);
1678                         else
1679                                 btrfs_end_write_no_snapshotting(root);
1680                         break;
1681                 }
1682
1683                 release_bytes = reserve_bytes;
1684 again:
1685                 /*
1686                  * This is going to setup the pages array with the number of
1687                  * pages we want, so we don't really need to worry about the
1688                  * contents of pages from loop to loop
1689                  */
1690                 ret = prepare_pages(inode, pages, num_pages,
1691                                     pos, write_bytes,
1692                                     force_page_uptodate);
1693                 if (ret) {
1694                         btrfs_delalloc_release_extents(BTRFS_I(inode),
1695                                                        reserve_bytes, true);
1696                         break;
1697                 }
1698
1699                 extents_locked = lock_and_cleanup_extent_if_need(
1700                                 BTRFS_I(inode), pages,
1701                                 num_pages, pos, write_bytes, &lockstart,
1702                                 &lockend, &cached_state);
1703                 if (extents_locked < 0) {
1704                         if (extents_locked == -EAGAIN)
1705                                 goto again;
1706                         btrfs_delalloc_release_extents(BTRFS_I(inode),
1707                                                        reserve_bytes, true);
1708                         ret = extents_locked;
1709                         break;
1710                 }
1711
1712                 copied = btrfs_copy_from_user(pos, write_bytes, pages, i);
1713
1714                 num_sectors = BTRFS_BYTES_TO_BLKS(fs_info, reserve_bytes);
1715                 dirty_sectors = round_up(copied + sector_offset,
1716                                         fs_info->sectorsize);
1717                 dirty_sectors = BTRFS_BYTES_TO_BLKS(fs_info, dirty_sectors);
1718
1719                 /*
1720                  * if we have trouble faulting in the pages, fall
1721                  * back to one page at a time
1722                  */
1723                 if (copied < write_bytes)
1724                         nrptrs = 1;
1725
1726                 if (copied == 0) {
1727                         force_page_uptodate = true;
1728                         dirty_sectors = 0;
1729                         dirty_pages = 0;
1730                 } else {
1731                         force_page_uptodate = false;
1732                         dirty_pages = DIV_ROUND_UP(copied + offset,
1733                                                    PAGE_SIZE);
1734                 }
1735
1736                 if (num_sectors > dirty_sectors) {
1737                         /* release everything except the sectors we dirtied */
1738                         release_bytes -= dirty_sectors <<
1739                                                 fs_info->sb->s_blocksize_bits;
1740                         if (only_release_metadata) {
1741                                 btrfs_delalloc_release_metadata(BTRFS_I(inode),
1742                                                         release_bytes, true);
1743                         } else {
1744                                 u64 __pos;
1745
1746                                 __pos = round_down(pos,
1747                                                    fs_info->sectorsize) +
1748                                         (dirty_pages << PAGE_SHIFT);
1749                                 btrfs_delalloc_release_space(inode,
1750                                                 data_reserved, __pos,
1751                                                 release_bytes, true);
1752                         }
1753                 }
1754
1755                 release_bytes = round_up(copied + sector_offset,
1756                                         fs_info->sectorsize);
1757
1758                 if (copied > 0)
1759                         ret = btrfs_dirty_pages(inode, pages, dirty_pages,
1760                                                 pos, copied, &cached_state);
1761                 if (extents_locked)
1762                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1763                                              lockstart, lockend, &cached_state);
1764                 btrfs_delalloc_release_extents(BTRFS_I(inode), reserve_bytes,
1765                                                true);
1766                 if (ret) {
1767                         btrfs_drop_pages(pages, num_pages);
1768                         break;
1769                 }
1770
1771                 release_bytes = 0;
1772                 if (only_release_metadata)
1773                         btrfs_end_write_no_snapshotting(root);
1774
1775                 if (only_release_metadata && copied > 0) {
1776                         lockstart = round_down(pos,
1777                                                fs_info->sectorsize);
1778                         lockend = round_up(pos + copied,
1779                                            fs_info->sectorsize) - 1;
1780
1781                         set_extent_bit(&BTRFS_I(inode)->io_tree, lockstart,
1782                                        lockend, EXTENT_NORESERVE, NULL,
1783                                        NULL, GFP_NOFS);
1784                         only_release_metadata = false;
1785                 }
1786
1787                 btrfs_drop_pages(pages, num_pages);
1788
1789                 cond_resched();
1790
1791                 balance_dirty_pages_ratelimited(inode->i_mapping);
1792                 if (dirty_pages < (fs_info->nodesize >> PAGE_SHIFT) + 1)
1793                         btrfs_btree_balance_dirty(fs_info);
1794
1795                 pos += copied;
1796                 num_written += copied;
1797         }
1798
1799         kfree(pages);
1800
1801         if (release_bytes) {
1802                 if (only_release_metadata) {
1803                         btrfs_end_write_no_snapshotting(root);
1804                         btrfs_delalloc_release_metadata(BTRFS_I(inode),
1805                                         release_bytes, true);
1806                 } else {
1807                         btrfs_delalloc_release_space(inode, data_reserved,
1808                                         round_down(pos, fs_info->sectorsize),
1809                                         release_bytes, true);
1810                 }
1811         }
1812
1813         extent_changeset_free(data_reserved);
1814         return num_written ? num_written : ret;
1815 }
1816
1817 static ssize_t __btrfs_direct_write(struct kiocb *iocb, struct iov_iter *from)
1818 {
1819         struct file *file = iocb->ki_filp;
1820         struct inode *inode = file_inode(file);
1821         loff_t pos;
1822         ssize_t written;
1823         ssize_t written_buffered;
1824         loff_t endbyte;
1825         int err;
1826
1827         written = generic_file_direct_write(iocb, from);
1828
1829         if (written < 0 || !iov_iter_count(from))
1830                 return written;
1831
1832         pos = iocb->ki_pos;
1833         written_buffered = btrfs_buffered_write(iocb, from);
1834         if (written_buffered < 0) {
1835                 err = written_buffered;
1836                 goto out;
1837         }
1838         /*
1839          * Ensure all data is persisted. We want the next direct IO read to be
1840          * able to read what was just written.
1841          */
1842         endbyte = pos + written_buffered - 1;
1843         err = btrfs_fdatawrite_range(inode, pos, endbyte);
1844         if (err)
1845                 goto out;
1846         err = filemap_fdatawait_range(inode->i_mapping, pos, endbyte);
1847         if (err)
1848                 goto out;
1849         written += written_buffered;
1850         iocb->ki_pos = pos + written_buffered;
1851         invalidate_mapping_pages(file->f_mapping, pos >> PAGE_SHIFT,
1852                                  endbyte >> PAGE_SHIFT);
1853 out:
1854         return written ? written : err;
1855 }
1856
1857 static void update_time_for_write(struct inode *inode)
1858 {
1859         struct timespec64 now;
1860
1861         if (IS_NOCMTIME(inode))
1862                 return;
1863
1864         now = current_time(inode);
1865         if (!timespec64_equal(&inode->i_mtime, &now))
1866                 inode->i_mtime = now;
1867
1868         if (!timespec64_equal(&inode->i_ctime, &now))
1869                 inode->i_ctime = now;
1870
1871         if (IS_I_VERSION(inode))
1872                 inode_inc_iversion(inode);
1873 }
1874
1875 static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
1876                                     struct iov_iter *from)
1877 {
1878         struct file *file = iocb->ki_filp;
1879         struct inode *inode = file_inode(file);
1880         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
1881         struct btrfs_root *root = BTRFS_I(inode)->root;
1882         u64 start_pos;
1883         u64 end_pos;
1884         ssize_t num_written = 0;
1885         bool sync = (file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host);
1886         ssize_t err;
1887         loff_t pos;
1888         size_t count = iov_iter_count(from);
1889         loff_t oldsize;
1890         int clean_page = 0;
1891
1892         if (!(iocb->ki_flags & IOCB_DIRECT) &&
1893             (iocb->ki_flags & IOCB_NOWAIT))
1894                 return -EOPNOTSUPP;
1895
1896         if (!inode_trylock(inode)) {
1897                 if (iocb->ki_flags & IOCB_NOWAIT)
1898                         return -EAGAIN;
1899                 inode_lock(inode);
1900         }
1901
1902         err = generic_write_checks(iocb, from);
1903         if (err <= 0) {
1904                 inode_unlock(inode);
1905                 return err;
1906         }
1907
1908         pos = iocb->ki_pos;
1909         if (iocb->ki_flags & IOCB_NOWAIT) {
1910                 /*
1911                  * We will allocate space in case nodatacow is not set,
1912                  * so bail
1913                  */
1914                 if (!(BTRFS_I(inode)->flags & (BTRFS_INODE_NODATACOW |
1915                                               BTRFS_INODE_PREALLOC)) ||
1916                     check_can_nocow(BTRFS_I(inode), pos, &count) <= 0) {
1917                         inode_unlock(inode);
1918                         return -EAGAIN;
1919                 }
1920         }
1921
1922         current->backing_dev_info = inode_to_bdi(inode);
1923         err = file_remove_privs(file);
1924         if (err) {
1925                 inode_unlock(inode);
1926                 goto out;
1927         }
1928
1929         /*
1930          * If BTRFS flips readonly due to some impossible error
1931          * (fs_info->fs_state now has BTRFS_SUPER_FLAG_ERROR),
1932          * although we have opened a file as writable, we have
1933          * to stop this write operation to ensure FS consistency.
1934          */
1935         if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
1936                 inode_unlock(inode);
1937                 err = -EROFS;
1938                 goto out;
1939         }
1940
1941         /*
1942          * We reserve space for updating the inode when we reserve space for the
1943          * extent we are going to write, so we will enospc out there.  We don't
1944          * need to start yet another transaction to update the inode as we will
1945          * update the inode when we finish writing whatever data we write.
1946          */
1947         update_time_for_write(inode);
1948
1949         start_pos = round_down(pos, fs_info->sectorsize);
1950         oldsize = i_size_read(inode);
1951         if (start_pos > oldsize) {
1952                 /* Expand hole size to cover write data, preventing empty gap */
1953                 end_pos = round_up(pos + count,
1954                                    fs_info->sectorsize);
1955                 err = btrfs_cont_expand(inode, oldsize, end_pos);
1956                 if (err) {
1957                         inode_unlock(inode);
1958                         goto out;
1959                 }
1960                 if (start_pos > round_up(oldsize, fs_info->sectorsize))
1961                         clean_page = 1;
1962         }
1963
1964         if (sync)
1965                 atomic_inc(&BTRFS_I(inode)->sync_writers);
1966
1967         if (iocb->ki_flags & IOCB_DIRECT) {
1968                 num_written = __btrfs_direct_write(iocb, from);
1969         } else {
1970                 num_written = btrfs_buffered_write(iocb, from);
1971                 if (num_written > 0)
1972                         iocb->ki_pos = pos + num_written;
1973                 if (clean_page)
1974                         pagecache_isize_extended(inode, oldsize,
1975                                                 i_size_read(inode));
1976         }
1977
1978         inode_unlock(inode);
1979
1980         /*
1981          * We also have to set last_sub_trans to the current log transid,
1982          * otherwise subsequent syncs to a file that's been synced in this
1983          * transaction will appear to have already occurred.
1984          */
1985         spin_lock(&BTRFS_I(inode)->lock);
1986         BTRFS_I(inode)->last_sub_trans = root->log_transid;
1987         spin_unlock(&BTRFS_I(inode)->lock);
1988         if (num_written > 0)
1989                 num_written = generic_write_sync(iocb, num_written);
1990
1991         if (sync)
1992                 atomic_dec(&BTRFS_I(inode)->sync_writers);
1993 out:
1994         current->backing_dev_info = NULL;
1995         return num_written ? num_written : err;
1996 }
1997
1998 int btrfs_release_file(struct inode *inode, struct file *filp)
1999 {
2000         struct btrfs_file_private *private = filp->private_data;
2001
2002         if (private && private->filldir_buf)
2003                 kfree(private->filldir_buf);
2004         kfree(private);
2005         filp->private_data = NULL;
2006
2007         /*
2008          * ordered_data_close is set by settattr when we are about to truncate
2009          * a file from a non-zero size to a zero size.  This tries to
2010          * flush down new bytes that may have been written if the
2011          * application were using truncate to replace a file in place.
2012          */
2013         if (test_and_clear_bit(BTRFS_INODE_ORDERED_DATA_CLOSE,
2014                                &BTRFS_I(inode)->runtime_flags))
2015                         filemap_flush(inode->i_mapping);
2016         return 0;
2017 }
2018
2019 static int start_ordered_ops(struct inode *inode, loff_t start, loff_t end)
2020 {
2021         int ret;
2022         struct blk_plug plug;
2023
2024         /*
2025          * This is only called in fsync, which would do synchronous writes, so
2026          * a plug can merge adjacent IOs as much as possible.  Esp. in case of
2027          * multiple disks using raid profile, a large IO can be split to
2028          * several segments of stripe length (currently 64K).
2029          */
2030         blk_start_plug(&plug);
2031         atomic_inc(&BTRFS_I(inode)->sync_writers);
2032         ret = btrfs_fdatawrite_range(inode, start, end);
2033         atomic_dec(&BTRFS_I(inode)->sync_writers);
2034         blk_finish_plug(&plug);
2035
2036         return ret;
2037 }
2038
2039 /*
2040  * fsync call for both files and directories.  This logs the inode into
2041  * the tree log instead of forcing full commits whenever possible.
2042  *
2043  * It needs to call filemap_fdatawait so that all ordered extent updates are
2044  * in the metadata btree are up to date for copying to the log.
2045  *
2046  * It drops the inode mutex before doing the tree log commit.  This is an
2047  * important optimization for directories because holding the mutex prevents
2048  * new operations on the dir while we write to disk.
2049  */
2050 int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
2051 {
2052         struct dentry *dentry = file_dentry(file);
2053         struct inode *inode = d_inode(dentry);
2054         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
2055         struct btrfs_root *root = BTRFS_I(inode)->root;
2056         struct btrfs_trans_handle *trans;
2057         struct btrfs_log_ctx ctx;
2058         int ret = 0, err;
2059         u64 len;
2060
2061         /*
2062          * The range length can be represented by u64, we have to do the typecasts
2063          * to avoid signed overflow if it's [0, LLONG_MAX] eg. from fsync()
2064          */
2065         len = (u64)end - (u64)start + 1;
2066         trace_btrfs_sync_file(file, datasync);
2067
2068         btrfs_init_log_ctx(&ctx, inode);
2069
2070         /*
2071          * We write the dirty pages in the range and wait until they complete
2072          * out of the ->i_mutex. If so, we can flush the dirty pages by
2073          * multi-task, and make the performance up.  See
2074          * btrfs_wait_ordered_range for an explanation of the ASYNC check.
2075          */
2076         ret = start_ordered_ops(inode, start, end);
2077         if (ret)
2078                 goto out;
2079
2080         inode_lock(inode);
2081         atomic_inc(&root->log_batch);
2082
2083         /*
2084          * We have to do this here to avoid the priority inversion of waiting on
2085          * IO of a lower priority task while holding a transaciton open.
2086          */
2087         ret = btrfs_wait_ordered_range(inode, start, len);
2088         if (ret) {
2089                 inode_unlock(inode);
2090                 goto out;
2091         }
2092         atomic_inc(&root->log_batch);
2093
2094         smp_mb();
2095         if (btrfs_inode_in_log(BTRFS_I(inode), fs_info->generation) ||
2096             BTRFS_I(inode)->last_trans <= fs_info->last_trans_committed) {
2097                 /*
2098                  * We've had everything committed since the last time we were
2099                  * modified so clear this flag in case it was set for whatever
2100                  * reason, it's no longer relevant.
2101                  */
2102                 clear_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
2103                           &BTRFS_I(inode)->runtime_flags);
2104                 /*
2105                  * An ordered extent might have started before and completed
2106                  * already with io errors, in which case the inode was not
2107                  * updated and we end up here. So check the inode's mapping
2108                  * for any errors that might have happened since we last
2109                  * checked called fsync.
2110                  */
2111                 ret = filemap_check_wb_err(inode->i_mapping, file->f_wb_err);
2112                 inode_unlock(inode);
2113                 goto out;
2114         }
2115
2116         /*
2117          * We use start here because we will need to wait on the IO to complete
2118          * in btrfs_sync_log, which could require joining a transaction (for
2119          * example checking cross references in the nocow path).  If we use join
2120          * here we could get into a situation where we're waiting on IO to
2121          * happen that is blocked on a transaction trying to commit.  With start
2122          * we inc the extwriter counter, so we wait for all extwriters to exit
2123          * before we start blocking join'ers.  This comment is to keep somebody
2124          * from thinking they are super smart and changing this to
2125          * btrfs_join_transaction *cough*Josef*cough*.
2126          */
2127         trans = btrfs_start_transaction(root, 0);
2128         if (IS_ERR(trans)) {
2129                 ret = PTR_ERR(trans);
2130                 inode_unlock(inode);
2131                 goto out;
2132         }
2133         trans->sync = true;
2134
2135         ret = btrfs_log_dentry_safe(trans, dentry, start, end, &ctx);
2136         if (ret < 0) {
2137                 /* Fallthrough and commit/free transaction. */
2138                 ret = 1;
2139         }
2140
2141         /* we've logged all the items and now have a consistent
2142          * version of the file in the log.  It is possible that
2143          * someone will come in and modify the file, but that's
2144          * fine because the log is consistent on disk, and we
2145          * have references to all of the file's extents
2146          *
2147          * It is possible that someone will come in and log the
2148          * file again, but that will end up using the synchronization
2149          * inside btrfs_sync_log to keep things safe.
2150          */
2151         inode_unlock(inode);
2152
2153         /*
2154          * If any of the ordered extents had an error, just return it to user
2155          * space, so that the application knows some writes didn't succeed and
2156          * can take proper action (retry for e.g.). Blindly committing the
2157          * transaction in this case, would fool userspace that everything was
2158          * successful. And we also want to make sure our log doesn't contain
2159          * file extent items pointing to extents that weren't fully written to -
2160          * just like in the non fast fsync path, where we check for the ordered
2161          * operation's error flag before writing to the log tree and return -EIO
2162          * if any of them had this flag set (btrfs_wait_ordered_range) -
2163          * therefore we need to check for errors in the ordered operations,
2164          * which are indicated by ctx.io_err.
2165          */
2166         if (ctx.io_err) {
2167                 btrfs_end_transaction(trans);
2168                 ret = ctx.io_err;
2169                 goto out;
2170         }
2171
2172         if (ret != BTRFS_NO_LOG_SYNC) {
2173                 if (!ret) {
2174                         ret = btrfs_sync_log(trans, root, &ctx);
2175                         if (!ret) {
2176                                 ret = btrfs_end_transaction(trans);
2177                                 goto out;
2178                         }
2179                 }
2180                 ret = btrfs_commit_transaction(trans);
2181         } else {
2182                 ret = btrfs_end_transaction(trans);
2183         }
2184 out:
2185         ASSERT(list_empty(&ctx.list));
2186         err = file_check_and_advance_wb_err(file);
2187         if (!ret)
2188                 ret = err;
2189         return ret > 0 ? -EIO : ret;
2190 }
2191
2192 static const struct vm_operations_struct btrfs_file_vm_ops = {
2193         .fault          = filemap_fault,
2194         .map_pages      = filemap_map_pages,
2195         .page_mkwrite   = btrfs_page_mkwrite,
2196 };
2197
2198 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
2199 {
2200         struct address_space *mapping = filp->f_mapping;
2201
2202         if (!mapping->a_ops->readpage)
2203                 return -ENOEXEC;
2204
2205         file_accessed(filp);
2206         vma->vm_ops = &btrfs_file_vm_ops;
2207
2208         return 0;
2209 }
2210
2211 static int hole_mergeable(struct btrfs_inode *inode, struct extent_buffer *leaf,
2212                           int slot, u64 start, u64 end)
2213 {
2214         struct btrfs_file_extent_item *fi;
2215         struct btrfs_key key;
2216
2217         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
2218                 return 0;
2219
2220         btrfs_item_key_to_cpu(leaf, &key, slot);
2221         if (key.objectid != btrfs_ino(inode) ||
2222             key.type != BTRFS_EXTENT_DATA_KEY)
2223                 return 0;
2224
2225         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
2226
2227         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG)
2228                 return 0;
2229
2230         if (btrfs_file_extent_disk_bytenr(leaf, fi))
2231                 return 0;
2232
2233         if (key.offset == end)
2234                 return 1;
2235         if (key.offset + btrfs_file_extent_num_bytes(leaf, fi) == start)
2236                 return 1;
2237         return 0;
2238 }
2239
2240 static int fill_holes(struct btrfs_trans_handle *trans,
2241                 struct btrfs_inode *inode,
2242                 struct btrfs_path *path, u64 offset, u64 end)
2243 {
2244         struct btrfs_fs_info *fs_info = trans->fs_info;
2245         struct btrfs_root *root = inode->root;
2246         struct extent_buffer *leaf;
2247         struct btrfs_file_extent_item *fi;
2248         struct extent_map *hole_em;
2249         struct extent_map_tree *em_tree = &inode->extent_tree;
2250         struct btrfs_key key;
2251         int ret;
2252
2253         if (btrfs_fs_incompat(fs_info, NO_HOLES))
2254                 goto out;
2255
2256         key.objectid = btrfs_ino(inode);
2257         key.type = BTRFS_EXTENT_DATA_KEY;
2258         key.offset = offset;
2259
2260         ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
2261         if (ret <= 0) {
2262                 /*
2263                  * We should have dropped this offset, so if we find it then
2264                  * something has gone horribly wrong.
2265                  */
2266                 if (ret == 0)
2267                         ret = -EINVAL;
2268                 return ret;
2269         }
2270
2271         leaf = path->nodes[0];
2272         if (hole_mergeable(inode, leaf, path->slots[0] - 1, offset, end)) {
2273                 u64 num_bytes;
2274
2275                 path->slots[0]--;
2276                 fi = btrfs_item_ptr(leaf, path->slots[0],
2277                                     struct btrfs_file_extent_item);
2278                 num_bytes = btrfs_file_extent_num_bytes(leaf, fi) +
2279                         end - offset;
2280                 btrfs_set_file_extent_num_bytes(leaf, fi, num_bytes);
2281                 btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
2282                 btrfs_set_file_extent_offset(leaf, fi, 0);
2283                 btrfs_mark_buffer_dirty(leaf);
2284                 goto out;
2285         }
2286
2287         if (hole_mergeable(inode, leaf, path->slots[0], offset, end)) {
2288                 u64 num_bytes;
2289
2290                 key.offset = offset;
2291                 btrfs_set_item_key_safe(fs_info, path, &key);
2292                 fi = btrfs_item_ptr(leaf, path->slots[0],
2293                                     struct btrfs_file_extent_item);
2294                 num_bytes = btrfs_file_extent_num_bytes(leaf, fi) + end -
2295                         offset;
2296                 btrfs_set_file_extent_num_bytes(leaf, fi, num_bytes);
2297                 btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
2298                 btrfs_set_file_extent_offset(leaf, fi, 0);
2299                 btrfs_mark_buffer_dirty(leaf);
2300                 goto out;
2301         }
2302         btrfs_release_path(path);
2303
2304         ret = btrfs_insert_file_extent(trans, root, btrfs_ino(inode),
2305                         offset, 0, 0, end - offset, 0, end - offset, 0, 0, 0);
2306         if (ret)
2307                 return ret;
2308
2309 out:
2310         btrfs_release_path(path);
2311
2312         hole_em = alloc_extent_map();
2313         if (!hole_em) {
2314                 btrfs_drop_extent_cache(inode, offset, end - 1, 0);
2315                 set_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &inode->runtime_flags);
2316         } else {
2317                 hole_em->start = offset;
2318                 hole_em->len = end - offset;
2319                 hole_em->ram_bytes = hole_em->len;
2320                 hole_em->orig_start = offset;
2321
2322                 hole_em->block_start = EXTENT_MAP_HOLE;
2323                 hole_em->block_len = 0;
2324                 hole_em->orig_block_len = 0;
2325                 hole_em->bdev = fs_info->fs_devices->latest_bdev;
2326                 hole_em->compress_type = BTRFS_COMPRESS_NONE;
2327                 hole_em->generation = trans->transid;
2328
2329                 do {
2330                         btrfs_drop_extent_cache(inode, offset, end - 1, 0);
2331                         write_lock(&em_tree->lock);
2332                         ret = add_extent_mapping(em_tree, hole_em, 1);
2333                         write_unlock(&em_tree->lock);
2334                 } while (ret == -EEXIST);
2335                 free_extent_map(hole_em);
2336                 if (ret)
2337                         set_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
2338                                         &inode->runtime_flags);
2339         }
2340
2341         return 0;
2342 }
2343
2344 /*
2345  * Find a hole extent on given inode and change start/len to the end of hole
2346  * extent.(hole/vacuum extent whose em->start <= start &&
2347  *         em->start + em->len > start)
2348  * When a hole extent is found, return 1 and modify start/len.
2349  */
2350 static int find_first_non_hole(struct inode *inode, u64 *start, u64 *len)
2351 {
2352         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
2353         struct extent_map *em;
2354         int ret = 0;
2355
2356         em = btrfs_get_extent(BTRFS_I(inode), NULL, 0,
2357                               round_down(*start, fs_info->sectorsize),
2358                               round_up(*len, fs_info->sectorsize), 0);
2359         if (IS_ERR(em))
2360                 return PTR_ERR(em);
2361
2362         /* Hole or vacuum extent(only exists in no-hole mode) */
2363         if (em->block_start == EXTENT_MAP_HOLE) {
2364                 ret = 1;
2365                 *len = em->start + em->len > *start + *len ?
2366                        0 : *start + *len - em->start - em->len;
2367                 *start = em->start + em->len;
2368         }
2369         free_extent_map(em);
2370         return ret;
2371 }
2372
2373 static int btrfs_punch_hole_lock_range(struct inode *inode,
2374                                        const u64 lockstart,
2375                                        const u64 lockend,
2376                                        struct extent_state **cached_state)
2377 {
2378         while (1) {
2379                 struct btrfs_ordered_extent *ordered;
2380                 int ret;
2381
2382                 truncate_pagecache_range(inode, lockstart, lockend);
2383
2384                 lock_extent_bits(&BTRFS_I(inode)->io_tree, lockstart, lockend,
2385                                  cached_state);
2386                 ordered = btrfs_lookup_first_ordered_extent(inode, lockend);
2387
2388                 /*
2389                  * We need to make sure we have no ordered extents in this range
2390                  * and nobody raced in and read a page in this range, if we did
2391                  * we need to try again.
2392                  */
2393                 if ((!ordered ||
2394                     (ordered->file_offset + ordered->len <= lockstart ||
2395                      ordered->file_offset > lockend)) &&
2396                      !filemap_range_has_page(inode->i_mapping,
2397                                              lockstart, lockend)) {
2398                         if (ordered)
2399                                 btrfs_put_ordered_extent(ordered);
2400                         break;
2401                 }
2402                 if (ordered)
2403                         btrfs_put_ordered_extent(ordered);
2404                 unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart,
2405                                      lockend, cached_state);
2406                 ret = btrfs_wait_ordered_range(inode, lockstart,
2407                                                lockend - lockstart + 1);
2408                 if (ret)
2409                         return ret;
2410         }
2411         return 0;
2412 }
2413
2414 static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
2415 {
2416         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
2417         struct btrfs_root *root = BTRFS_I(inode)->root;
2418         struct extent_state *cached_state = NULL;
2419         struct btrfs_path *path;
2420         struct btrfs_block_rsv *rsv;
2421         struct btrfs_trans_handle *trans;
2422         u64 lockstart;
2423         u64 lockend;
2424         u64 tail_start;
2425         u64 tail_len;
2426         u64 orig_start = offset;
2427         u64 cur_offset;
2428         u64 min_size = btrfs_calc_trans_metadata_size(fs_info, 1);
2429         u64 drop_end;
2430         int ret = 0;
2431         int err = 0;
2432         unsigned int rsv_count;
2433         bool same_block;
2434         bool no_holes = btrfs_fs_incompat(fs_info, NO_HOLES);
2435         u64 ino_size;
2436         bool truncated_block = false;
2437         bool updated_inode = false;
2438
2439         ret = btrfs_wait_ordered_range(inode, offset, len);
2440         if (ret)
2441                 return ret;
2442
2443         inode_lock(inode);
2444         ino_size = round_up(inode->i_size, fs_info->sectorsize);
2445         ret = find_first_non_hole(inode, &offset, &len);
2446         if (ret < 0)
2447                 goto out_only_mutex;
2448         if (ret && !len) {
2449                 /* Already in a large hole */
2450                 ret = 0;
2451                 goto out_only_mutex;
2452         }
2453
2454         lockstart = round_up(offset, btrfs_inode_sectorsize(inode));
2455         lockend = round_down(offset + len,
2456                              btrfs_inode_sectorsize(inode)) - 1;
2457         same_block = (BTRFS_BYTES_TO_BLKS(fs_info, offset))
2458                 == (BTRFS_BYTES_TO_BLKS(fs_info, offset + len - 1));
2459         /*
2460          * We needn't truncate any block which is beyond the end of the file
2461          * because we are sure there is no data there.
2462          */
2463         /*
2464          * Only do this if we are in the same block and we aren't doing the
2465          * entire block.
2466          */
2467         if (same_block && len < fs_info->sectorsize) {
2468                 if (offset < ino_size) {
2469                         truncated_block = true;
2470                         ret = btrfs_truncate_block(inode, offset, len, 0);
2471                 } else {
2472                         ret = 0;
2473                 }
2474                 goto out_only_mutex;
2475         }
2476
2477         /* zero back part of the first block */
2478         if (offset < ino_size) {
2479                 truncated_block = true;
2480                 ret = btrfs_truncate_block(inode, offset, 0, 0);
2481                 if (ret) {
2482                         inode_unlock(inode);
2483                         return ret;
2484                 }
2485         }
2486
2487         /* Check the aligned pages after the first unaligned page,
2488          * if offset != orig_start, which means the first unaligned page
2489          * including several following pages are already in holes,
2490          * the extra check can be skipped */
2491         if (offset == orig_start) {
2492                 /* after truncate page, check hole again */
2493                 len = offset + len - lockstart;
2494                 offset = lockstart;
2495                 ret = find_first_non_hole(inode, &offset, &len);
2496                 if (ret < 0)
2497                         goto out_only_mutex;
2498                 if (ret && !len) {
2499                         ret = 0;
2500                         goto out_only_mutex;
2501                 }
2502                 lockstart = offset;
2503         }
2504
2505         /* Check the tail unaligned part is in a hole */
2506         tail_start = lockend + 1;
2507         tail_len = offset + len - tail_start;
2508         if (tail_len) {
2509                 ret = find_first_non_hole(inode, &tail_start, &tail_len);
2510                 if (unlikely(ret < 0))
2511                         goto out_only_mutex;
2512                 if (!ret) {
2513                         /* zero the front end of the last page */
2514                         if (tail_start + tail_len < ino_size) {
2515                                 truncated_block = true;
2516                                 ret = btrfs_truncate_block(inode,
2517                                                         tail_start + tail_len,
2518                                                         0, 1);
2519                                 if (ret)
2520                                         goto out_only_mutex;
2521                         }
2522                 }
2523         }
2524
2525         if (lockend < lockstart) {
2526                 ret = 0;
2527                 goto out_only_mutex;
2528         }
2529
2530         ret = btrfs_punch_hole_lock_range(inode, lockstart, lockend,
2531                                           &cached_state);
2532         if (ret) {
2533                 inode_unlock(inode);
2534                 goto out_only_mutex;
2535         }
2536
2537         path = btrfs_alloc_path();
2538         if (!path) {
2539                 ret = -ENOMEM;
2540                 goto out;
2541         }
2542
2543         rsv = btrfs_alloc_block_rsv(fs_info, BTRFS_BLOCK_RSV_TEMP);
2544         if (!rsv) {
2545                 ret = -ENOMEM;
2546                 goto out_free;
2547         }
2548         rsv->size = btrfs_calc_trans_metadata_size(fs_info, 1);
2549         rsv->failfast = 1;
2550
2551         /*
2552          * 1 - update the inode
2553          * 1 - removing the extents in the range
2554          * 1 - adding the hole extent if no_holes isn't set
2555          */
2556         rsv_count = no_holes ? 2 : 3;
2557         trans = btrfs_start_transaction(root, rsv_count);
2558         if (IS_ERR(trans)) {
2559                 err = PTR_ERR(trans);
2560                 goto out_free;
2561         }
2562
2563         ret = btrfs_block_rsv_migrate(&fs_info->trans_block_rsv, rsv,
2564                                       min_size, false);
2565         BUG_ON(ret);
2566         trans->block_rsv = rsv;
2567
2568         cur_offset = lockstart;
2569         len = lockend - cur_offset;
2570         while (cur_offset < lockend) {
2571                 ret = __btrfs_drop_extents(trans, root, inode, path,
2572                                            cur_offset, lockend + 1,
2573                                            &drop_end, 1, 0, 0, NULL);
2574                 if (ret != -ENOSPC)
2575                         break;
2576
2577                 trans->block_rsv = &fs_info->trans_block_rsv;
2578
2579                 if (cur_offset < drop_end && cur_offset < ino_size) {
2580                         ret = fill_holes(trans, BTRFS_I(inode), path,
2581                                         cur_offset, drop_end);
2582                         if (ret) {
2583                                 /*
2584                                  * If we failed then we didn't insert our hole
2585                                  * entries for the area we dropped, so now the
2586                                  * fs is corrupted, so we must abort the
2587                                  * transaction.
2588                                  */
2589                                 btrfs_abort_transaction(trans, ret);
2590                                 err = ret;
2591                                 break;
2592                         }
2593                 }
2594
2595                 cur_offset = drop_end;
2596
2597                 ret = btrfs_update_inode(trans, root, inode);
2598                 if (ret) {
2599                         err = ret;
2600                         break;
2601                 }
2602
2603                 btrfs_end_transaction(trans);
2604                 btrfs_btree_balance_dirty(fs_info);
2605
2606                 trans = btrfs_start_transaction(root, rsv_count);
2607                 if (IS_ERR(trans)) {
2608                         ret = PTR_ERR(trans);
2609                         trans = NULL;
2610                         break;
2611                 }
2612
2613                 ret = btrfs_block_rsv_migrate(&fs_info->trans_block_rsv,
2614                                               rsv, min_size, false);
2615                 BUG_ON(ret);    /* shouldn't happen */
2616                 trans->block_rsv = rsv;
2617
2618                 ret = find_first_non_hole(inode, &cur_offset, &len);
2619                 if (unlikely(ret < 0))
2620                         break;
2621                 if (ret && !len) {
2622                         ret = 0;
2623                         break;
2624                 }
2625         }
2626
2627         if (ret) {
2628                 err = ret;
2629                 goto out_trans;
2630         }
2631
2632         trans->block_rsv = &fs_info->trans_block_rsv;
2633         /*
2634          * If we are using the NO_HOLES feature we might have had already an
2635          * hole that overlaps a part of the region [lockstart, lockend] and
2636          * ends at (or beyond) lockend. Since we have no file extent items to
2637          * represent holes, drop_end can be less than lockend and so we must
2638          * make sure we have an extent map representing the existing hole (the
2639          * call to __btrfs_drop_extents() might have dropped the existing extent
2640          * map representing the existing hole), otherwise the fast fsync path
2641          * will not record the existence of the hole region
2642          * [existing_hole_start, lockend].
2643          */
2644         if (drop_end <= lockend)
2645                 drop_end = lockend + 1;
2646         /*
2647          * Don't insert file hole extent item if it's for a range beyond eof
2648          * (because it's useless) or if it represents a 0 bytes range (when
2649          * cur_offset == drop_end).
2650          */
2651         if (cur_offset < ino_size && cur_offset < drop_end) {
2652                 ret = fill_holes(trans, BTRFS_I(inode), path,
2653                                 cur_offset, drop_end);
2654                 if (ret) {
2655                         /* Same comment as above. */
2656                         btrfs_abort_transaction(trans, ret);
2657                         err = ret;
2658                         goto out_trans;
2659                 }
2660         }
2661
2662 out_trans:
2663         if (!trans)
2664                 goto out_free;
2665
2666         inode_inc_iversion(inode);
2667         inode->i_mtime = inode->i_ctime = current_time(inode);
2668
2669         trans->block_rsv = &fs_info->trans_block_rsv;
2670         ret = btrfs_update_inode(trans, root, inode);
2671         updated_inode = true;
2672         btrfs_end_transaction(trans);
2673         btrfs_btree_balance_dirty(fs_info);
2674 out_free:
2675         btrfs_free_path(path);
2676         btrfs_free_block_rsv(fs_info, rsv);
2677 out:
2678         unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
2679                              &cached_state);
2680 out_only_mutex:
2681         if (!updated_inode && truncated_block && !ret && !err) {
2682                 /*
2683                  * If we only end up zeroing part of a page, we still need to
2684                  * update the inode item, so that all the time fields are
2685                  * updated as well as the necessary btrfs inode in memory fields
2686                  * for detecting, at fsync time, if the inode isn't yet in the
2687                  * log tree or it's there but not up to date.
2688                  */
2689                 trans = btrfs_start_transaction(root, 1);
2690                 if (IS_ERR(trans)) {
2691                         err = PTR_ERR(trans);
2692                 } else {
2693                         err = btrfs_update_inode(trans, root, inode);
2694                         ret = btrfs_end_transaction(trans);
2695                 }
2696         }
2697         inode_unlock(inode);
2698         if (ret && !err)
2699                 err = ret;
2700         return err;
2701 }
2702
2703 /* Helper structure to record which range is already reserved */
2704 struct falloc_range {
2705         struct list_head list;
2706         u64 start;
2707         u64 len;
2708 };
2709
2710 /*
2711  * Helper function to add falloc range
2712  *
2713  * Caller should have locked the larger range of extent containing
2714  * [start, len)
2715  */
2716 static int add_falloc_range(struct list_head *head, u64 start, u64 len)
2717 {
2718         struct falloc_range *prev = NULL;
2719         struct falloc_range *range = NULL;
2720
2721         if (list_empty(head))
2722                 goto insert;
2723
2724         /*
2725          * As fallocate iterate by bytenr order, we only need to check
2726          * the last range.
2727          */
2728         prev = list_entry(head->prev, struct falloc_range, list);
2729         if (prev->start + prev->len == start) {
2730                 prev->len += len;
2731                 return 0;
2732         }
2733 insert:
2734         range = kmalloc(sizeof(*range), GFP_KERNEL);
2735         if (!range)
2736                 return -ENOMEM;
2737         range->start = start;
2738         range->len = len;
2739         list_add_tail(&range->list, head);
2740         return 0;
2741 }
2742
2743 static int btrfs_fallocate_update_isize(struct inode *inode,
2744                                         const u64 end,
2745                                         const int mode)
2746 {
2747         struct btrfs_trans_handle *trans;
2748         struct btrfs_root *root = BTRFS_I(inode)->root;
2749         int ret;
2750         int ret2;
2751
2752         if (mode & FALLOC_FL_KEEP_SIZE || end <= i_size_read(inode))
2753                 return 0;
2754
2755         trans = btrfs_start_transaction(root, 1);
2756         if (IS_ERR(trans))
2757                 return PTR_ERR(trans);
2758
2759         inode->i_ctime = current_time(inode);
2760         i_size_write(inode, end);
2761         btrfs_ordered_update_i_size(inode, end, NULL);
2762         ret = btrfs_update_inode(trans, root, inode);
2763         ret2 = btrfs_end_transaction(trans);
2764
2765         return ret ? ret : ret2;
2766 }
2767
2768 enum {
2769         RANGE_BOUNDARY_WRITTEN_EXTENT = 0,
2770         RANGE_BOUNDARY_PREALLOC_EXTENT = 1,
2771         RANGE_BOUNDARY_HOLE = 2,
2772 };
2773
2774 static int btrfs_zero_range_check_range_boundary(struct inode *inode,
2775                                                  u64 offset)
2776 {
2777         const u64 sectorsize = btrfs_inode_sectorsize(inode);
2778         struct extent_map *em;
2779         int ret;
2780
2781         offset = round_down(offset, sectorsize);
2782         em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, offset, sectorsize, 0);
2783         if (IS_ERR(em))
2784                 return PTR_ERR(em);
2785
2786         if (em->block_start == EXTENT_MAP_HOLE)
2787                 ret = RANGE_BOUNDARY_HOLE;
2788         else if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
2789                 ret = RANGE_BOUNDARY_PREALLOC_EXTENT;
2790         else
2791                 ret = RANGE_BOUNDARY_WRITTEN_EXTENT;
2792
2793         free_extent_map(em);
2794         return ret;
2795 }
2796
2797 static int btrfs_zero_range(struct inode *inode,
2798                             loff_t offset,
2799                             loff_t len,
2800                             const int mode)
2801 {
2802         struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
2803         struct extent_map *em;
2804         struct extent_changeset *data_reserved = NULL;
2805         int ret;
2806         u64 alloc_hint = 0;
2807         const u64 sectorsize = btrfs_inode_sectorsize(inode);
2808         u64 alloc_start = round_down(offset, sectorsize);
2809         u64 alloc_end = round_up(offset + len, sectorsize);
2810         u64 bytes_to_reserve = 0;
2811         bool space_reserved = false;
2812
2813         inode_dio_wait(inode);
2814
2815         em = btrfs_get_extent(BTRFS_I(inode), NULL, 0,
2816                               alloc_start, alloc_end - alloc_start, 0);
2817         if (IS_ERR(em)) {
2818                 ret = PTR_ERR(em);
2819                 goto out;
2820         }
2821
2822         /*
2823          * Avoid hole punching and extent allocation for some cases. More cases
2824          * could be considered, but these are unlikely common and we keep things
2825          * as simple as possible for now. Also, intentionally, if the target
2826          * range contains one or more prealloc extents together with regular
2827          * extents and holes, we drop all the existing extents and allocate a
2828          * new prealloc extent, so that we get a larger contiguous disk extent.
2829          */
2830         if (em->start <= alloc_start &&
2831             test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) {
2832                 const u64 em_end = em->start + em->len;
2833
2834                 if (em_end >= offset + len) {
2835                         /*
2836                          * The whole range is already a prealloc extent,
2837                          * do nothing except updating the inode's i_size if
2838                          * needed.
2839                          */
2840                         free_extent_map(em);
2841                         ret = btrfs_fallocate_update_isize(inode, offset + len,
2842                                                            mode);
2843                         goto out;
2844                 }
2845                 /*
2846                  * Part of the range is already a prealloc extent, so operate
2847                  * only on the remaining part of the range.
2848                  */
2849                 alloc_start = em_end;
2850                 ASSERT(IS_ALIGNED(alloc_start, sectorsize));
2851                 len = offset + len - alloc_start;
2852                 offset = alloc_start;
2853                 alloc_hint = em->block_start + em->len;
2854         }
2855         free_extent_map(em);
2856
2857         if (BTRFS_BYTES_TO_BLKS(fs_info, offset) ==
2858             BTRFS_BYTES_TO_BLKS(fs_info, offset + len - 1)) {
2859                 em = btrfs_get_extent(BTRFS_I(inode), NULL, 0,
2860                                       alloc_start, sectorsize, 0);
2861                 if (IS_ERR(em)) {
2862                         ret = PTR_ERR(em);
2863                         goto out;
2864                 }
2865
2866                 if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) {
2867                         free_extent_map(em);
2868                         ret = btrfs_fallocate_update_isize(inode, offset + len,
2869                                                            mode);
2870                         goto out;
2871                 }
2872                 if (len < sectorsize && em->block_start != EXTENT_MAP_HOLE) {
2873                         free_extent_map(em);
2874                         ret = btrfs_truncate_block(inode, offset, len, 0);
2875                         if (!ret)
2876                                 ret = btrfs_fallocate_update_isize(inode,
2877                                                                    offset + len,
2878                                                                    mode);
2879                         return ret;
2880                 }
2881                 free_extent_map(em);
2882                 alloc_start = round_down(offset, sectorsize);
2883                 alloc_end = alloc_start + sectorsize;
2884                 goto reserve_space;
2885         }
2886
2887         alloc_start = round_up(offset, sectorsize);
2888         alloc_end = round_down(offset + len, sectorsize);
2889
2890         /*
2891          * For unaligned ranges, check the pages at the boundaries, they might
2892          * map to an extent, in which case we need to partially zero them, or
2893          * they might map to a hole, in which case we need our allocation range
2894          * to cover them.
2895          */
2896         if (!IS_ALIGNED(offset, sectorsize)) {
2897                 ret = btrfs_zero_range_check_range_boundary(inode, offset);
2898                 if (ret < 0)
2899                         goto out;
2900                 if (ret == RANGE_BOUNDARY_HOLE) {
2901                         alloc_start = round_down(offset, sectorsize);
2902                         ret = 0;
2903                 } else if (ret == RANGE_BOUNDARY_WRITTEN_EXTENT) {
2904                         ret = btrfs_truncate_block(inode, offset, 0, 0);
2905                         if (ret)
2906                                 goto out;
2907                 } else {
2908                         ret = 0;
2909                 }
2910         }
2911
2912         if (!IS_ALIGNED(offset + len, sectorsize)) {
2913                 ret = btrfs_zero_range_check_range_boundary(inode,
2914                                                             offset + len);
2915                 if (ret < 0)
2916                         goto out;
2917                 if (ret == RANGE_BOUNDARY_HOLE) {
2918                         alloc_end = round_up(offset + len, sectorsize);
2919                         ret = 0;
2920                 } else if (ret == RANGE_BOUNDARY_WRITTEN_EXTENT) {
2921                         ret = btrfs_truncate_block(inode, offset + len, 0, 1);
2922                         if (ret)
2923                                 goto out;
2924                 } else {
2925                         ret = 0;
2926                 }
2927         }
2928
2929 reserve_space:
2930         if (alloc_start < alloc_end) {
2931                 struct extent_state *cached_state = NULL;
2932                 const u64 lockstart = alloc_start;
2933                 const u64 lockend = alloc_end - 1;
2934
2935                 bytes_to_reserve = alloc_end - alloc_start;
2936                 ret = btrfs_alloc_data_chunk_ondemand(BTRFS_I(inode),
2937                                                       bytes_to_reserve);
2938                 if (ret < 0)
2939                         goto out;
2940                 space_reserved = true;
2941                 ret = btrfs_qgroup_reserve_data(inode, &data_reserved,
2942                                                 alloc_start, bytes_to_reserve);
2943                 if (ret)
2944                         goto out;
2945                 ret = btrfs_punch_hole_lock_range(inode, lockstart, lockend,
2946                                                   &cached_state);
2947                 if (ret)
2948                         goto out;
2949                 ret = btrfs_prealloc_file_range(inode, mode, alloc_start,
2950                                                 alloc_end - alloc_start,
2951                                                 i_blocksize(inode),
2952                                                 offset + len, &alloc_hint);
2953                 unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart,
2954                                      lockend, &cached_state);
2955                 /* btrfs_prealloc_file_range releases reserved space on error */
2956                 if (ret) {
2957                         space_reserved = false;
2958                         goto out;
2959                 }
2960         }
2961         ret = btrfs_fallocate_update_isize(inode, offset + len, mode);
2962  out:
2963         if (ret && space_reserved)
2964                 btrfs_free_reserved_data_space(inode, data_reserved,
2965                                                alloc_start, bytes_to_reserve);
2966         extent_changeset_free(data_reserved);
2967
2968         return ret;
2969 }
2970
2971 static long btrfs_fallocate(struct file *file, int mode,
2972                             loff_t offset, loff_t len)
2973 {
2974         struct inode *inode = file_inode(file);
2975         struct extent_state *cached_state = NULL;
2976         struct extent_changeset *data_reserved = NULL;
2977         struct falloc_range *range;
2978         struct falloc_range *tmp;
2979         struct list_head reserve_list;
2980         u64 cur_offset;
2981         u64 last_byte;
2982         u64 alloc_start;
2983         u64 alloc_end;
2984         u64 alloc_hint = 0;
2985         u64 locked_end;
2986         u64 actual_end = 0;
2987         struct extent_map *em;
2988         int blocksize = btrfs_inode_sectorsize(inode);
2989         int ret;
2990
2991         alloc_start = round_down(offset, blocksize);
2992         alloc_end = round_up(offset + len, blocksize);
2993         cur_offset = alloc_start;
2994
2995         /* Make sure we aren't being give some crap mode */
2996         if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |
2997                      FALLOC_FL_ZERO_RANGE))
2998                 return -EOPNOTSUPP;
2999
3000         if (mode & FALLOC_FL_PUNCH_HOLE)
3001                 return btrfs_punch_hole(inode, offset, len);
3002
3003         /*
3004          * Only trigger disk allocation, don't trigger qgroup reserve
3005          *
3006          * For qgroup space, it will be checked later.
3007          */
3008         if (!(mode & FALLOC_FL_ZERO_RANGE)) {
3009                 ret = btrfs_alloc_data_chunk_ondemand(BTRFS_I(inode),
3010                                                       alloc_end - alloc_start);
3011                 if (ret < 0)
3012                         return ret;
3013         }
3014
3015         inode_lock(inode);
3016
3017         if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size) {
3018                 ret = inode_newsize_ok(inode, offset + len);
3019                 if (ret)
3020                         goto out;
3021         }
3022
3023         /*
3024          * TODO: Move these two operations after we have checked
3025          * accurate reserved space, or fallocate can still fail but
3026          * with page truncated or size expanded.
3027          *
3028          * But that's a minor problem and won't do much harm BTW.
3029          */
3030         if (alloc_start > inode->i_size) {
3031                 ret = btrfs_cont_expand(inode, i_size_read(inode),
3032                                         alloc_start);
3033                 if (ret)
3034                         goto out;
3035         } else if (offset + len > inode->i_size) {
3036                 /*
3037                  * If we are fallocating from the end of the file onward we
3038                  * need to zero out the end of the block if i_size lands in the
3039                  * middle of a block.
3040                  */
3041                 ret = btrfs_truncate_block(inode, inode->i_size, 0, 0);
3042                 if (ret)
3043                         goto out;
3044         }
3045
3046         /*
3047          * wait for ordered IO before we have any locks.  We'll loop again
3048          * below with the locks held.
3049          */
3050         ret = btrfs_wait_ordered_range(inode, alloc_start,
3051                                        alloc_end - alloc_start);
3052         if (ret)
3053                 goto out;
3054
3055         if (mode & FALLOC_FL_ZERO_RANGE) {
3056                 ret = btrfs_zero_range(inode, offset, len, mode);
3057                 inode_unlock(inode);
3058                 return ret;
3059         }
3060
3061         locked_end = alloc_end - 1;
3062         while (1) {
3063                 struct btrfs_ordered_extent *ordered;
3064
3065                 /* the extent lock is ordered inside the running
3066                  * transaction
3067                  */
3068                 lock_extent_bits(&BTRFS_I(inode)->io_tree, alloc_start,
3069                                  locked_end, &cached_state);
3070                 ordered = btrfs_lookup_first_ordered_extent(inode, locked_end);
3071
3072                 if (ordered &&
3073                     ordered->file_offset + ordered->len > alloc_start &&
3074                     ordered->file_offset < alloc_end) {
3075                         btrfs_put_ordered_extent(ordered);
3076                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
3077                                              alloc_start, locked_end,
3078                                              &cached_state);
3079                         /*
3080                          * we can't wait on the range with the transaction
3081                          * running or with the extent lock held
3082                          */
3083                         ret = btrfs_wait_ordered_range(inode, alloc_start,
3084                                                        alloc_end - alloc_start);
3085                         if (ret)
3086                                 goto out;
3087                 } else {
3088                         if (ordered)
3089                                 btrfs_put_ordered_extent(ordered);
3090                         break;
3091                 }
3092         }
3093
3094         /* First, check if we exceed the qgroup limit */
3095         INIT_LIST_HEAD(&reserve_list);
3096         while (cur_offset < alloc_end) {
3097                 em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, cur_offset,
3098                                       alloc_end - cur_offset, 0);
3099                 if (IS_ERR(em)) {
3100                         ret = PTR_ERR(em);
3101                         break;
3102                 }
3103                 last_byte = min(extent_map_end(em), alloc_end);
3104                 actual_end = min_t(u64, extent_map_end(em), offset + len);
3105                 last_byte = ALIGN(last_byte, blocksize);
3106                 if (em->block_start == EXTENT_MAP_HOLE ||
3107                     (cur_offset >= inode->i_size &&
3108                      !test_bit(EXTENT_FLAG_PREALLOC, &em->flags))) {
3109                         ret = add_falloc_range(&reserve_list, cur_offset,
3110                                                last_byte - cur_offset);
3111                         if (ret < 0) {
3112                                 free_extent_map(em);
3113                                 break;
3114                         }
3115                         ret = btrfs_qgroup_reserve_data(inode, &data_reserved,
3116                                         cur_offset, last_byte - cur_offset);
3117                         if (ret < 0) {
3118                                 free_extent_map(em);
3119                                 break;
3120                         }
3121                 } else {
3122                         /*
3123                          * Do not need to reserve unwritten extent for this
3124                          * range, free reserved data space first, otherwise
3125                          * it'll result in false ENOSPC error.
3126                          */
3127                         btrfs_free_reserved_data_space(inode, data_reserved,
3128                                         cur_offset, last_byte - cur_offset);
3129                 }
3130                 free_extent_map(em);
3131                 cur_offset = last_byte;
3132         }
3133
3134         /*
3135          * If ret is still 0, means we're OK to fallocate.
3136          * Or just cleanup the list and exit.
3137          */
3138         list_for_each_entry_safe(range, tmp, &reserve_list, list) {
3139                 if (!ret)
3140                         ret = btrfs_prealloc_file_range(inode, mode,
3141                                         range->start,
3142                                         range->len, i_blocksize(inode),
3143                                         offset + len, &alloc_hint);
3144                 else
3145                         btrfs_free_reserved_data_space(inode,
3146                                         data_reserved, range->start,
3147                                         range->len);
3148                 list_del(&range->list);
3149                 kfree(range);
3150         }
3151         if (ret < 0)
3152                 goto out_unlock;
3153
3154         /*
3155          * We didn't need to allocate any more space, but we still extended the
3156          * size of the file so we need to update i_size and the inode item.
3157          */
3158         ret = btrfs_fallocate_update_isize(inode, actual_end, mode);
3159 out_unlock:
3160         unlock_extent_cached(&BTRFS_I(inode)->io_tree, alloc_start, locked_end,
3161                              &cached_state);
3162 out:
3163         inode_unlock(inode);
3164         /* Let go of our reservation. */
3165         if (ret != 0 && !(mode & FALLOC_FL_ZERO_RANGE))
3166                 btrfs_free_reserved_data_space(inode, data_reserved,
3167                                 alloc_start, alloc_end - cur_offset);
3168         extent_changeset_free(data_reserved);
3169         return ret;
3170 }
3171
3172 static int find_desired_extent(struct inode *inode, loff_t *offset, int whence)
3173 {
3174         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
3175         struct extent_map *em = NULL;
3176         struct extent_state *cached_state = NULL;
3177         u64 lockstart;
3178         u64 lockend;
3179         u64 start;
3180         u64 len;
3181         int ret = 0;
3182
3183         if (inode->i_size == 0)
3184                 return -ENXIO;
3185
3186         /*
3187          * *offset can be negative, in this case we start finding DATA/HOLE from
3188          * the very start of the file.
3189          */
3190         start = max_t(loff_t, 0, *offset);
3191
3192         lockstart = round_down(start, fs_info->sectorsize);
3193         lockend = round_up(i_size_read(inode),
3194                            fs_info->sectorsize);
3195         if (lockend <= lockstart)
3196                 lockend = lockstart + fs_info->sectorsize;
3197         lockend--;
3198         len = lockend - lockstart + 1;
3199
3200         lock_extent_bits(&BTRFS_I(inode)->io_tree, lockstart, lockend,
3201                          &cached_state);
3202
3203         while (start < inode->i_size) {
3204                 em = btrfs_get_extent_fiemap(BTRFS_I(inode), NULL, 0,
3205                                 start, len, 0);
3206                 if (IS_ERR(em)) {
3207                         ret = PTR_ERR(em);
3208                         em = NULL;
3209                         break;
3210                 }
3211
3212                 if (whence == SEEK_HOLE &&
3213                     (em->block_start == EXTENT_MAP_HOLE ||
3214                      test_bit(EXTENT_FLAG_PREALLOC, &em->flags)))
3215                         break;
3216                 else if (whence == SEEK_DATA &&
3217                            (em->block_start != EXTENT_MAP_HOLE &&
3218                             !test_bit(EXTENT_FLAG_PREALLOC, &em->flags)))
3219                         break;
3220
3221                 start = em->start + em->len;
3222                 free_extent_map(em);
3223                 em = NULL;
3224                 cond_resched();
3225         }
3226         free_extent_map(em);
3227         if (!ret) {
3228                 if (whence == SEEK_DATA && start >= inode->i_size)
3229                         ret = -ENXIO;
3230                 else
3231                         *offset = min_t(loff_t, start, inode->i_size);
3232         }
3233         unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
3234                              &cached_state);
3235         return ret;
3236 }
3237
3238 static loff_t btrfs_file_llseek(struct file *file, loff_t offset, int whence)
3239 {
3240         struct inode *inode = file->f_mapping->host;
3241         int ret;
3242
3243         inode_lock(inode);
3244         switch (whence) {
3245         case SEEK_END:
3246         case SEEK_CUR:
3247                 offset = generic_file_llseek(file, offset, whence);
3248                 goto out;
3249         case SEEK_DATA:
3250         case SEEK_HOLE:
3251                 if (offset >= i_size_read(inode)) {
3252                         inode_unlock(inode);
3253                         return -ENXIO;
3254                 }
3255
3256                 ret = find_desired_extent(inode, &offset, whence);
3257                 if (ret) {
3258                         inode_unlock(inode);
3259                         return ret;
3260                 }
3261         }
3262
3263         offset = vfs_setpos(file, offset, inode->i_sb->s_maxbytes);
3264 out:
3265         inode_unlock(inode);
3266         return offset;
3267 }
3268
3269 static int btrfs_file_open(struct inode *inode, struct file *filp)
3270 {
3271         filp->f_mode |= FMODE_NOWAIT;
3272         return generic_file_open(inode, filp);
3273 }
3274
3275 const struct file_operations btrfs_file_operations = {
3276         .llseek         = btrfs_file_llseek,
3277         .read_iter      = generic_file_read_iter,
3278         .splice_read    = generic_file_splice_read,
3279         .write_iter     = btrfs_file_write_iter,
3280         .mmap           = btrfs_file_mmap,
3281         .open           = btrfs_file_open,
3282         .release        = btrfs_release_file,
3283         .fsync          = btrfs_sync_file,
3284         .fallocate      = btrfs_fallocate,
3285         .unlocked_ioctl = btrfs_ioctl,
3286 #ifdef CONFIG_COMPAT
3287         .compat_ioctl   = btrfs_compat_ioctl,
3288 #endif
3289         .clone_file_range = btrfs_clone_file_range,
3290         .dedupe_file_range = btrfs_dedupe_file_range,
3291 };
3292
3293 void __cold btrfs_auto_defrag_exit(void)
3294 {
3295         kmem_cache_destroy(btrfs_inode_defrag_cachep);
3296 }
3297
3298 int __init btrfs_auto_defrag_init(void)
3299 {
3300         btrfs_inode_defrag_cachep = kmem_cache_create("btrfs_inode_defrag",
3301                                         sizeof(struct inode_defrag), 0,
3302                                         SLAB_MEM_SPREAD,
3303                                         NULL);
3304         if (!btrfs_inode_defrag_cachep)
3305                 return -ENOMEM;
3306
3307         return 0;
3308 }
3309
3310 int btrfs_fdatawrite_range(struct inode *inode, loff_t start, loff_t end)
3311 {
3312         int ret;
3313
3314         /*
3315          * So with compression we will find and lock a dirty page and clear the
3316          * first one as dirty, setup an async extent, and immediately return
3317          * with the entire range locked but with nobody actually marked with
3318          * writeback.  So we can't just filemap_write_and_wait_range() and
3319          * expect it to work since it will just kick off a thread to do the
3320          * actual work.  So we need to call filemap_fdatawrite_range _again_
3321          * since it will wait on the page lock, which won't be unlocked until
3322          * after the pages have been marked as writeback and so we're good to go
3323          * from there.  We have to do this otherwise we'll miss the ordered
3324          * extents and that results in badness.  Please Josef, do not think you
3325          * know better and pull this out at some point in the future, it is
3326          * right and you are wrong.
3327          */
3328         ret = filemap_fdatawrite_range(inode->i_mapping, start, end);
3329         if (!ret && test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
3330                              &BTRFS_I(inode)->runtime_flags))
3331                 ret = filemap_fdatawrite_range(inode->i_mapping, start, end);
3332
3333         return ret;
3334 }