fs/btrfs/file.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/fs.h>
  20 #include <linux/pagemap.h>
  21 #include <linux/highmem.h>
  22 #include <linux/time.h>
  23 #include <linux/init.h>
  24 #include <linux/string.h>
  25 #include <linux/backing-dev.h>
  26 #include <linux/mpage.h>
  27 #include <linux/falloc.h>
  28 #include <linux/swap.h>
  29 #include <linux/writeback.h>
  30 #include <linux/statfs.h>
  31 #include <linux/compat.h>
  32 #include <linux/slab.h>
  33 #include <linux/btrfs.h>
  34 #include "ctree.h"
  35 #include "disk-io.h"
  36 #include "transaction.h"
  37 #include "btrfs_inode.h"
  38 #include "print-tree.h"
  39 #include "tree-log.h"
  40 #include "locking.h"
  41 #include "compat.h"
  42 #include "volumes.h"
  43
  44 static struct kmem_cache *btrfs_inode_defrag_cachep;
  45 /*
  46  * when auto defrag is enabled we
  47  * queue up these defrag structs to remember which
  48  * inodes need defragging passes
  49  */
  50 struct inode_defrag {
  51         struct rb_node rb_node;
  52         /* objectid */
  53         u64 ino;
  54         /*
  55          * transid where the defrag was added, we search for
  56          * extents newer than this
  57          */
  58         u64 transid;
  59
  60         /* root objectid */
  61         u64 root;
  62
  63         /* last offset we were able to defrag */
  64         u64 last_offset;
  65
  66         /* if we've wrapped around back to zero once already */
  67         int cycled;
  68 };
  69
  70 static int __compare_inode_defrag(struct inode_defrag *defrag1,
  71                                   struct inode_defrag *defrag2)
  72 {
  73         if (defrag1->root > defrag2->root)
  74                 return 1;
  75         else if (defrag1->root < defrag2->root)
  76                 return -1;
  77         else if (defrag1->ino > defrag2->ino)
  78                 return 1;
  79         else if (defrag1->ino < defrag2->ino)
  80                 return -1;
  81         else
  82                 return 0;
  83 }
  84
  85 /* pop a record for an inode into the defrag tree.  The lock
  86  * must be held already
  87  *
  88  * If you're inserting a record for an older transid than an
  89  * existing record, the transid already in the tree is lowered
  90  *
  91  * If an existing record is found the defrag item you
  92  * pass in is freed
  93  */
  94 static int __btrfs_add_inode_defrag(struct inode *inode,
  95                                     struct inode_defrag *defrag)
  96 {
  97         struct btrfs_root *root = BTRFS_I(inode)->root;
  98         struct inode_defrag *entry;
  99         struct rb_node **p;
 100         struct rb_node *parent = NULL;
 101         int ret;
 102
 103         p = &root->fs_info->defrag_inodes.rb_node;
 104         while (*p) {
 105                 parent = *p;
 106                 entry = rb_entry(parent, struct inode_defrag, rb_node);
 107
 108                 ret = __compare_inode_defrag(defrag, entry);
 109                 if (ret < 0)
 110                         p = &parent->rb_left;
 111                 else if (ret > 0)
 112                         p = &parent->rb_right;
 113                 else {
 114                         /* if we're reinserting an entry for
 115                          * an old defrag run, make sure to
 116                          * lower the transid of our existing record
 117                          */
 118                         if (defrag->transid < entry->transid)
 119                                 entry->transid = defrag->transid;
 120                         if (defrag->last_offset > entry->last_offset)
 121                                 entry->last_offset = defrag->last_offset;
 122                         return -EEXIST;
 123                 }
 124         }
 125         set_bit(BTRFS_INODE_IN_DEFRAG, &BTRFS_I(inode)->runtime_flags);
 126         rb_link_node(&defrag->rb_node, parent, p);
 127         rb_insert_color(&defrag->rb_node, &root->fs_info->defrag_inodes);
 128         return 0;
 129 }
 130
 131 static inline int __need_auto_defrag(struct btrfs_root *root)
 132 {
 133         if (!btrfs_test_opt(root, AUTO_DEFRAG))
 134                 return 0;
 135
 136         if (btrfs_fs_closing(root->fs_info))
 137                 return 0;
 138
 139         return 1;
 140 }
 141
 142 /*
 143  * insert a defrag record for this inode if auto defrag is
 144  * enabled
 145  */
 146 int btrfs_add_inode_defrag(struct btrfs_trans_handle *trans,
 147                            struct inode *inode)
 148 {
 149         struct btrfs_root *root = BTRFS_I(inode)->root;
 150         struct inode_defrag *defrag;
 151         u64 transid;
 152         int ret;
 153
 154         if (!__need_auto_defrag(root))
 155                 return 0;
 156
 157         if (test_bit(BTRFS_INODE_IN_DEFRAG, &BTRFS_I(inode)->runtime_flags))
 158                 return 0;
 159
 160         if (trans)
 161                 transid = trans->transid;
 162         else
 163                 transid = BTRFS_I(inode)->root->last_trans;
 164
 165         defrag = kmem_cache_zalloc(btrfs_inode_defrag_cachep, GFP_NOFS);
 166         if (!defrag)
 167                 return -ENOMEM;
 168
 169         defrag->ino = btrfs_ino(inode);
 170         defrag->transid = transid;
 171         defrag->root = root->root_key.objectid;
 172
 173         spin_lock(&root->fs_info->defrag_inodes_lock);
 174         if (!test_bit(BTRFS_INODE_IN_DEFRAG, &BTRFS_I(inode)->runtime_flags)) {
 175                 /*
 176                  * If we set IN_DEFRAG flag and evict the inode from memory,
 177                  * and then re-read this inode, this new inode doesn't have
 178                  * IN_DEFRAG flag. At the case, we may find the existed defrag.
 179                  */
 180                 ret = __btrfs_add_inode_defrag(inode, defrag);
 181                 if (ret)
 182                         kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
 183         } else {
 184                 kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
 185         }
 186         spin_unlock(&root->fs_info->defrag_inodes_lock);
 187         return 0;
 188 }
 189
 190 /*
 191  * Requeue the defrag object. If there is a defrag object that points to
 192  * the same inode in the tree, we will merge them together (by
 193  * __btrfs_add_inode_defrag()) and free the one that we want to requeue.
 194  */
 195 void btrfs_requeue_inode_defrag(struct inode *inode,
 196                                 struct inode_defrag *defrag)
 197 {
 198         struct btrfs_root *root = BTRFS_I(inode)->root;
 199         int ret;
 200
 201         if (!__need_auto_defrag(root))
 202                 goto out;
 203
 204         /*
 205          * Here we don't check the IN_DEFRAG flag, because we need merge
 206          * them together.
 207          */
 208         spin_lock(&root->fs_info->defrag_inodes_lock);
 209         ret = __btrfs_add_inode_defrag(inode, defrag);
 210         spin_unlock(&root->fs_info->defrag_inodes_lock);
 211         if (ret)
 212                 goto out;
 213         return;
 214 out:
 215         kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
 216 }
 217
 218 /*
 219  * pick the defragable inode that we want, if it doesn't exist, we will get
 220  * the next one.
 221  */
 222 static struct inode_defrag *
 223 btrfs_pick_defrag_inode(struct btrfs_fs_info *fs_info, u64 root, u64 ino)
 224 {
 225         struct inode_defrag *entry = NULL;
 226         struct inode_defrag tmp;
 227         struct rb_node *p;
 228         struct rb_node *parent = NULL;
 229         int ret;
 230
 231         tmp.ino = ino;
 232         tmp.root = root;
 233
 234         spin_lock(&fs_info->defrag_inodes_lock);
 235         p = fs_info->defrag_inodes.rb_node;
 236         while (p) {
 237                 parent = p;
 238                 entry = rb_entry(parent, struct inode_defrag, rb_node);
 239
 240                 ret = __compare_inode_defrag(&tmp, entry);
 241                 if (ret < 0)
 242                         p = parent->rb_left;
 243                 else if (ret > 0)
 244                         p = parent->rb_right;
 245                 else
 246                         goto out;
 247         }
 248
 249         if (parent && __compare_inode_defrag(&tmp, entry) > 0) {
 250                 parent = rb_next(parent);
 251                 if (parent)
 252                         entry = rb_entry(parent, struct inode_defrag, rb_node);
 253                 else
 254                         entry = NULL;
 255         }
 256 out:
 257         if (entry)
 258                 rb_erase(parent, &fs_info->defrag_inodes);
 259         spin_unlock(&fs_info->defrag_inodes_lock);
 260         return entry;
 261 }
 262
 263 void btrfs_cleanup_defrag_inodes(struct btrfs_fs_info *fs_info)
 264 {
 265         struct inode_defrag *defrag;
 266         struct rb_node *node;
 267
 268         spin_lock(&fs_info->defrag_inodes_lock);
 269         node = rb_first(&fs_info->defrag_inodes);
 270         while (node) {
 271                 rb_erase(node, &fs_info->defrag_inodes);
 272                 defrag = rb_entry(node, struct inode_defrag, rb_node);
 273                 kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
 274
 275                 if (need_resched()) {
 276                         spin_unlock(&fs_info->defrag_inodes_lock);
 277                         cond_resched();
 278                         spin_lock(&fs_info->defrag_inodes_lock);
 279                 }
 280
 281                 node = rb_first(&fs_info->defrag_inodes);
 282         }
 283         spin_unlock(&fs_info->defrag_inodes_lock);
 284 }
 285
 286 #define BTRFS_DEFRAG_BATCH      1024
 287
 288 static int __btrfs_run_defrag_inode(struct btrfs_fs_info *fs_info,
 289                                     struct inode_defrag *defrag)
 290 {
 291         struct btrfs_root *inode_root;
 292         struct inode *inode;
 293         struct btrfs_key key;
 294         struct btrfs_ioctl_defrag_range_args range;
 295         int num_defrag;
 296         int index;
 297         int ret;
 298
 299         /* get the inode */
 300         key.objectid = defrag->root;
 301         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
 302         key.offset = (u64)-1;
 303
 304         index = srcu_read_lock(&fs_info->subvol_srcu);
 305
 306         inode_root = btrfs_read_fs_root_no_name(fs_info, &key);
 307         if (IS_ERR(inode_root)) {
 308                 ret = PTR_ERR(inode_root);
 309                 goto cleanup;
 310         }
 311         if (btrfs_root_refs(&inode_root->root_item) == 0) {
 312                 ret = -ENOENT;
 313                 goto cleanup;
 314         }
 315
 316         key.objectid = defrag->ino;
 317         btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
 318         key.offset = 0;
 319         inode = btrfs_iget(fs_info->sb, &key, inode_root, NULL);
 320         if (IS_ERR(inode)) {
 321                 ret = PTR_ERR(inode);
 322                 goto cleanup;
 323         }
 324         srcu_read_unlock(&fs_info->subvol_srcu, index);
 325
 326         /* do a chunk of defrag */
 327         clear_bit(BTRFS_INODE_IN_DEFRAG, &BTRFS_I(inode)->runtime_flags);
 328         memset(&range, 0, sizeof(range));
 329         range.len = (u64)-1;
 330         range.start = defrag->last_offset;
 331
 332         sb_start_write(fs_info->sb);
 333         num_defrag = btrfs_defrag_file(inode, NULL, &range, defrag->transid,
 334                                        BTRFS_DEFRAG_BATCH);
 335         sb_end_write(fs_info->sb);
 336         /*
 337          * if we filled the whole defrag batch, there
 338          * must be more work to do.  Queue this defrag
 339          * again
 340          */
 341         if (num_defrag == BTRFS_DEFRAG_BATCH) {
 342                 defrag->last_offset = range.start;
 343                 btrfs_requeue_inode_defrag(inode, defrag);
 344         } else if (defrag->last_offset && !defrag->cycled) {
 345                 /*
 346                  * we didn't fill our defrag batch, but
 347                  * we didn't start at zero.  Make sure we loop
 348                  * around to the start of the file.
 349                  */
 350                 defrag->last_offset = 0;
 351                 defrag->cycled = 1;
 352                 btrfs_requeue_inode_defrag(inode, defrag);
 353         } else {
 354                 kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
 355         }
 356
 357         iput(inode);
 358         return 0;
 359 cleanup:
 360         srcu_read_unlock(&fs_info->subvol_srcu, index);
 361         kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
 362         return ret;
 363 }
 364
 365 /*
 366  * run through the list of inodes in the FS that need
 367  * defragging
 368  */
 369 int btrfs_run_defrag_inodes(struct btrfs_fs_info *fs_info)
 370 {
 371         struct inode_defrag *defrag;
 372         u64 first_ino = 0;
 373         u64 root_objectid = 0;
 374
 375         atomic_inc(&fs_info->defrag_running);
 376         while(1) {
 377                 if (!__need_auto_defrag(fs_info->tree_root))
 378                         break;
 379
 380                 /* find an inode to defrag */
 381                 defrag = btrfs_pick_defrag_inode(fs_info, root_objectid,
 382                                                  first_ino);
 383                 if (!defrag) {
 384                         if (root_objectid || first_ino) {
 385                                 root_objectid = 0;
 386                                 first_ino = 0;
 387                                 continue;
 388                         } else {
 389                                 break;
 390                         }
 391                 }
 392
 393                 first_ino = defrag->ino + 1;
 394                 root_objectid = defrag->root;
 395
 396                 __btrfs_run_defrag_inode(fs_info, defrag);
 397         }
 398         atomic_dec(&fs_info->defrag_running);
 399
 400         /*
 401          * during unmount, we use the transaction_wait queue to
 402          * wait for the defragger to stop
 403          */
 404         wake_up(&fs_info->transaction_wait);
 405         return 0;
 406 }
 407
 408 /* simple helper to fault in pages and copy.  This should go away
 409  * and be replaced with calls into generic code.
 410  */
 411 static noinline int btrfs_copy_from_user(loff_t pos, int num_pages,
 412                                          size_t write_bytes,
 413                                          struct page **prepared_pages,
 414                                          struct iov_iter *i)
 415 {
 416         size_t copied = 0;
 417         size_t total_copied = 0;
 418         int pg = 0;
 419         int offset = pos & (PAGE_CACHE_SIZE - 1);
 420
 421         while (write_bytes > 0) {
 422                 size_t count = min_t(size_t,
 423                                      PAGE_CACHE_SIZE - offset, write_bytes);
 424                 struct page *page = prepared_pages[pg];
 425                 /*
 426                  * Copy data from userspace to the current page
 427                  *
 428                  * Disable pagefault to avoid recursive lock since
 429                  * the pages are already locked
 430                  */
 431                 pagefault_disable();
 432                 copied = iov_iter_copy_from_user_atomic(page, i, offset, count);
 433                 pagefault_enable();
 434
 435                 /* Flush processor's dcache for this page */
 436                 flush_dcache_page(page);
 437
 438                 /*
 439                  * if we get a partial write, we can end up with
 440                  * partially up to date pages.  These add
 441                  * a lot of complexity, so make sure they don't
 442                  * happen by forcing this copy to be retried.
 443                  *
 444                  * The rest of the btrfs_file_write code will fall
 445                  * back to page at a time copies after we return 0.
 446                  */
 447                 if (!PageUptodate(page) && copied < count)
 448                         copied = 0;
 449
 450                 iov_iter_advance(i, copied);
 451                 write_bytes -= copied;
 452                 total_copied += copied;
 453
 454                 /* Return to btrfs_file_aio_write to fault page */
 455                 if (unlikely(copied == 0))
 456                         break;
 457
 458                 if (unlikely(copied < PAGE_CACHE_SIZE - offset)) {
 459                         offset += copied;
 460                 } else {
 461                         pg++;
 462                         offset = 0;
 463                 }
 464         }
 465         return total_copied;
 466 }
 467
 468 /*
 469  * unlocks pages after btrfs_file_write is done with them
 470  */
 471 void btrfs_drop_pages(struct page **pages, size_t num_pages)
 472 {
 473         size_t i;
 474         for (i = 0; i < num_pages; i++) {
 475                 /* page checked is some magic around finding pages that
 476                  * have been modified without going through btrfs_set_page_dirty
 477                  * clear it here
 478                  */
 479                 ClearPageChecked(pages[i]);
 480                 unlock_page(pages[i]);
 481                 mark_page_accessed(pages[i]);
 482                 page_cache_release(pages[i]);
 483         }
 484 }
 485
 486 /*
 487  * after copy_from_user, pages need to be dirtied and we need to make
 488  * sure holes are created between the current EOF and the start of
 489  * any next extents (if required).
 490  *
 491  * this also makes the decision about creating an inline extent vs
 492  * doing real data extents, marking pages dirty and delalloc as required.
 493  */
 494 int btrfs_dirty_pages(struct btrfs_root *root, struct inode *inode,
 495                       struct page **pages, size_t num_pages,
 496                       loff_t pos, size_t write_bytes,
 497                       struct extent_state **cached)
 498 {
 499         int err = 0;
 500         int i;
 501         u64 num_bytes;
 502         u64 start_pos;
 503         u64 end_of_last_block;
 504         u64 end_pos = pos + write_bytes;
 505         loff_t isize = i_size_read(inode);
 506
 507         start_pos = pos & ~((u64)root->sectorsize - 1);
 508         num_bytes = (write_bytes + pos - start_pos +
 509                     root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
 510
 511         end_of_last_block = start_pos + num_bytes - 1;
 512         err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block,
 513                                         cached);
 514         if (err)
 515                 return err;
 516
 517         for (i = 0; i < num_pages; i++) {
 518                 struct page *p = pages[i];
 519                 SetPageUptodate(p);
 520                 ClearPageChecked(p);
 521                 set_page_dirty(p);
 522         }
 523
 524         /*
 525          * we've only changed i_size in ram, and we haven't updated
 526          * the disk i_size.  There is no need to log the inode
 527          * at this time.
 528          */
 529         if (end_pos > isize)
 530                 i_size_write(inode, end_pos);
 531         return 0;
 532 }
 533
 534 /*
 535  * this drops all the extents in the cache that intersect the range
 536  * [start, end].  Existing extents are split as required.
 537  */
 538 void btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
 539                              int skip_pinned)
 540 {
 541         struct extent_map *em;
 542         struct extent_map *split = NULL;
 543         struct extent_map *split2 = NULL;
 544         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
 545         u64 len = end - start + 1;
 546         u64 gen;
 547         int ret;
 548         int testend = 1;
 549         unsigned long flags;
 550         int compressed = 0;
 551
 552         WARN_ON(end < start);
 553         if (end == (u64)-1) {
 554                 len = (u64)-1;
 555                 testend = 0;
 556         }
 557         while (1) {
 558                 int no_splits = 0;
 559
 560                 if (!split)
 561                         split = alloc_extent_map();
 562                 if (!split2)
 563                         split2 = alloc_extent_map();
 564                 if (!split || !split2)
 565                         no_splits = 1;
 566
 567                 write_lock(&em_tree->lock);
 568                 em = lookup_extent_mapping(em_tree, start, len);
 569                 if (!em) {
 570                         write_unlock(&em_tree->lock);
 571                         break;
 572                 }
 573                 flags = em->flags;
 574                 gen = em->generation;
 575                 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
 576                         if (testend && em->start + em->len >= start + len) {
 577                                 free_extent_map(em);
 578                                 write_unlock(&em_tree->lock);
 579                                 break;
 580                         }
 581                         start = em->start + em->len;
 582                         if (testend)
 583                                 len = start + len - (em->start + em->len);
 584                         free_extent_map(em);
 585                         write_unlock(&em_tree->lock);
 586                         continue;
 587                 }
 588                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 589                 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
 590                 remove_extent_mapping(em_tree, em);
 591                 if (no_splits)
 592                         goto next;
 593
 594                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 595                     em->start < start) {
 596                         split->start = em->start;
 597                         split->len = start - em->start;
 598                         split->orig_start = em->orig_start;
 599                         split->block_start = em->block_start;
 600
 601                         if (compressed)
 602                                 split->block_len = em->block_len;
 603                         else
 604                                 split->block_len = split->len;
 605                         split->orig_block_len = max(split->block_len,
 606                                                     em->orig_block_len);
 607                         split->generation = gen;
 608                         split->bdev = em->bdev;
 609                         split->flags = flags;
 610                         split->compress_type = em->compress_type;
 611                         ret = add_extent_mapping(em_tree, split);
 612                         BUG_ON(ret); /* Logic error */
 613                         list_move(&split->list, &em_tree->modified_extents);
 614                         free_extent_map(split);
 615                         split = split2;
 616                         split2 = NULL;
 617                 }
 618                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 619                     testend && em->start + em->len > start + len) {
 620                         u64 diff = start + len - em->start;
 621
 622                         split->start = start + len;
 623                         split->len = em->start + em->len - (start + len);
 624                         split->bdev = em->bdev;
 625                         split->flags = flags;
 626                         split->compress_type = em->compress_type;
 627                         split->generation = gen;
 628                         split->orig_block_len = max(em->block_len,
 629                                                     em->orig_block_len);
 630
 631                         if (compressed) {
 632                                 split->block_len = em->block_len;
 633                                 split->block_start = em->block_start;
 634                                 split->orig_start = em->orig_start;
 635                         } else {
 636                                 split->block_len = split->len;
 637                                 split->block_start = em->block_start + diff;
 638                                 split->orig_start = em->orig_start;
 639                         }
 640
 641                         ret = add_extent_mapping(em_tree, split);
 642                         BUG_ON(ret); /* Logic error */
 643                         list_move(&split->list, &em_tree->modified_extents);
 644                         free_extent_map(split);
 645                         split = NULL;
 646                 }
 647 next:
 648                 write_unlock(&em_tree->lock);
 649
 650                 /* once for us */
 651                 free_extent_map(em);
 652                 /* once for the tree*/
 653                 free_extent_map(em);
 654         }
 655         if (split)
 656                 free_extent_map(split);
 657         if (split2)
 658                 free_extent_map(split2);
 659 }
 660
 661 /*
 662  * this is very complex, but the basic idea is to drop all extents
 663  * in the range start - end.  hint_block is filled in with a block number
 664  * that would be a good hint to the block allocator for this file.
 665  *
 666  * If an extent intersects the range but is not entirely inside the range
 667  * it is either truncated or split.  Anything entirely inside the range
 668  * is deleted from the tree.
 669  */
 670 int __btrfs_drop_extents(struct btrfs_trans_handle *trans,
 671                          struct btrfs_root *root, struct inode *inode,
 672                          struct btrfs_path *path, u64 start, u64 end,
 673                          u64 *drop_end, int drop_cache)
 674 {
 675         struct extent_buffer *leaf;
 676         struct btrfs_file_extent_item *fi;
 677         struct btrfs_key key;
 678         struct btrfs_key new_key;
 679         u64 ino = btrfs_ino(inode);
 680         u64 search_start = start;
 681         u64 disk_bytenr = 0;
 682         u64 num_bytes = 0;
 683         u64 extent_offset = 0;
 684         u64 extent_end = 0;
 685         int del_nr = 0;
 686         int del_slot = 0;
 687         int extent_type;
 688         int recow;
 689         int ret;
 690         int modify_tree = -1;
 691         int update_refs = (root->ref_cows || root == root->fs_info->tree_root);
 692         int found = 0;
 693
 694         if (drop_cache)
 695                 btrfs_drop_extent_cache(inode, start, end - 1, 0);
 696
 697         if (start >= BTRFS_I(inode)->disk_i_size)
 698                 modify_tree = 0;
 699
 700         while (1) {
 701                 recow = 0;
 702                 ret = btrfs_lookup_file_extent(trans, root, path, ino,
 703                                                search_start, modify_tree);
 704                 if (ret < 0)
 705                         break;
 706                 if (ret > 0 && path->slots[0] > 0 && search_start == start) {
 707                         leaf = path->nodes[0];
 708                         btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 709                         if (key.objectid == ino &&
 710                             key.type == BTRFS_EXTENT_DATA_KEY)
 711                                 path->slots[0]--;
 712                 }
 713                 ret = 0;
 714 next_slot:
 715                 leaf = path->nodes[0];
 716                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 717                         BUG_ON(del_nr > 0);
 718                         ret = btrfs_next_leaf(root, path);
 719                         if (ret < 0)
 720                                 break;
 721                         if (ret > 0) {
 722                                 ret = 0;
 723                                 break;
 724                         }
 725                         leaf = path->nodes[0];
 726                         recow = 1;
 727                 }
 728
 729                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 730                 if (key.objectid > ino ||
 731                     key.type > BTRFS_EXTENT_DATA_KEY || key.offset >= end)
 732                         break;
 733
 734                 fi = btrfs_item_ptr(leaf, path->slots[0],
 735                                     struct btrfs_file_extent_item);
 736                 extent_type = btrfs_file_extent_type(leaf, fi);
 737
 738                 if (extent_type == BTRFS_FILE_EXTENT_REG ||
 739                     extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
 740                         disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 741                         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
 742                         extent_offset = btrfs_file_extent_offset(leaf, fi);
 743                         extent_end = key.offset +
 744                                 btrfs_file_extent_num_bytes(leaf, fi);
 745                 } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 746                         extent_end = key.offset +
 747                                 btrfs_file_extent_inline_len(leaf, fi);
 748                 } else {
 749                         WARN_ON(1);
 750                         extent_end = search_start;
 751                 }
 752
 753                 if (extent_end <= search_start) {
 754                         path->slots[0]++;
 755                         goto next_slot;
 756                 }
 757
 758                 found = 1;
 759                 search_start = max(key.offset, start);
 760                 if (recow || !modify_tree) {
 761                         modify_tree = -1;
 762                         btrfs_release_path(path);
 763                         continue;
 764                 }
 765
 766                 /*
 767                  *     | - range to drop - |
 768                  *  | -------- extent -------- |
 769                  */
 770                 if (start > key.offset && end < extent_end) {
 771                         BUG_ON(del_nr > 0);
 772                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 773
 774                         memcpy(&new_key, &key, sizeof(new_key));
 775                         new_key.offset = start;
 776                         ret = btrfs_duplicate_item(trans, root, path,
 777                                                    &new_key);
 778                         if (ret == -EAGAIN) {
 779                                 btrfs_release_path(path);
 780                                 continue;
 781                         }
 782                         if (ret < 0)
 783                                 break;
 784
 785                         leaf = path->nodes[0];
 786                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
 787                                             struct btrfs_file_extent_item);
 788                         btrfs_set_file_extent_num_bytes(leaf, fi,
 789                                                         start - key.offset);
 790
 791                         fi = btrfs_item_ptr(leaf, path->slots[0],
 792                                             struct btrfs_file_extent_item);
 793
 794                         extent_offset += start - key.offset;
 795                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
 796                         btrfs_set_file_extent_num_bytes(leaf, fi,
 797                                                         extent_end - start);
 798                         btrfs_mark_buffer_dirty(leaf);
 799
 800                         if (update_refs && disk_bytenr > 0) {
 801                                 ret = btrfs_inc_extent_ref(trans, root,
 802                                                 disk_bytenr, num_bytes, 0,
 803                                                 root->root_key.objectid,
 804                                                 new_key.objectid,
 805                                                 start - extent_offset, 0);
 806                                 BUG_ON(ret); /* -ENOMEM */
 807                         }
 808                         key.offset = start;
 809                 }
 810                 /*
 811                  *  | ---- range to drop ----- |
 812                  *      | -------- extent -------- |
 813                  */
 814                 if (start <= key.offset && end < extent_end) {
 815                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 816
 817                         memcpy(&new_key, &key, sizeof(new_key));
 818                         new_key.offset = end;
 819                         btrfs_set_item_key_safe(trans, root, path, &new_key);
 820
 821                         extent_offset += end - key.offset;
 822                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
 823                         btrfs_set_file_extent_num_bytes(leaf, fi,
 824                                                         extent_end - end);
 825                         btrfs_mark_buffer_dirty(leaf);
 826                         if (update_refs && disk_bytenr > 0)
 827                                 inode_sub_bytes(inode, end - key.offset);
 828                         break;
 829                 }
 830
 831                 search_start = extent_end;
 832                 /*
 833                  *       | ---- range to drop ----- |
 834                  *  | -------- extent -------- |
 835                  */
 836                 if (start > key.offset && end >= extent_end) {
 837                         BUG_ON(del_nr > 0);
 838                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 839
 840                         btrfs_set_file_extent_num_bytes(leaf, fi,
 841                                                         start - key.offset);
 842                         btrfs_mark_buffer_dirty(leaf);
 843                         if (update_refs && disk_bytenr > 0)
 844                                 inode_sub_bytes(inode, extent_end - start);
 845                         if (end == extent_end)
 846                                 break;
 847
 848                         path->slots[0]++;
 849                         goto next_slot;
 850                 }
 851
 852                 /*
 853                  *  | ---- range to drop ----- |
 854                  *    | ------ extent ------ |
 855                  */
 856                 if (start <= key.offset && end >= extent_end) {
 857                         if (del_nr == 0) {
 858                                 del_slot = path->slots[0];
 859                                 del_nr = 1;
 860                         } else {
 861                                 BUG_ON(del_slot + del_nr != path->slots[0]);
 862                                 del_nr++;
 863                         }
 864
 865                         if (update_refs &&
 866                             extent_type == BTRFS_FILE_EXTENT_INLINE) {
 867                                 inode_sub_bytes(inode,
 868                                                 extent_end - key.offset);
 869                                 extent_end = ALIGN(extent_end,
 870                                                    root->sectorsize);
 871                         } else if (update_refs && disk_bytenr > 0) {
 872                                 ret = btrfs_free_extent(trans, root,
 873                                                 disk_bytenr, num_bytes, 0,
 874                                                 root->root_key.objectid,
 875                                                 key.objectid, key.offset -
 876                                                 extent_offset, 0);
 877                                 BUG_ON(ret); /* -ENOMEM */
 878                                 inode_sub_bytes(inode,
 879                                                 extent_end - key.offset);
 880                         }
 881
 882                         if (end == extent_end)
 883                                 break;
 884
 885                         if (path->slots[0] + 1 < btrfs_header_nritems(leaf)) {
 886                                 path->slots[0]++;
 887                                 goto next_slot;
 888                         }
 889
 890                         ret = btrfs_del_items(trans, root, path, del_slot,
 891                                               del_nr);
 892                         if (ret) {
 893                                 btrfs_abort_transaction(trans, root, ret);
 894                                 break;
 895                         }
 896
 897                         del_nr = 0;
 898                         del_slot = 0;
 899
 900                         btrfs_release_path(path);
 901                         continue;
 902                 }
 903
 904                 BUG_ON(1);
 905         }
 906
 907         if (!ret && del_nr > 0) {
 908                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
 909                 if (ret)
 910                         btrfs_abort_transaction(trans, root, ret);
 911         }
 912
 913         if (drop_end)
 914                 *drop_end = found ? min(end, extent_end) : end;
 915         btrfs_release_path(path);
 916         return ret;
 917 }
 918
 919 int btrfs_drop_extents(struct btrfs_trans_handle *trans,
 920                        struct btrfs_root *root, struct inode *inode, u64 start,
 921                        u64 end, int drop_cache)
 922 {
 923         struct btrfs_path *path;
 924         int ret;
 925
 926         path = btrfs_alloc_path();
 927         if (!path)
 928                 return -ENOMEM;
 929         ret = __btrfs_drop_extents(trans, root, inode, path, start, end, NULL,
 930                                    drop_cache);
 931         btrfs_free_path(path);
 932         return ret;
 933 }
 934
 935 static int extent_mergeable(struct extent_buffer *leaf, int slot,
 936                             u64 objectid, u64 bytenr, u64 orig_offset,
 937                             u64 *start, u64 *end)
 938 {
 939         struct btrfs_file_extent_item *fi;
 940         struct btrfs_key key;
 941         u64 extent_end;
 942
 943         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
 944                 return 0;
 945
 946         btrfs_item_key_to_cpu(leaf, &key, slot);
 947         if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
 948                 return 0;
 949
 950         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
 951         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
 952             btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
 953             btrfs_file_extent_offset(leaf, fi) != key.offset - orig_offset ||
 954             btrfs_file_extent_compression(leaf, fi) ||
 955             btrfs_file_extent_encryption(leaf, fi) ||
 956             btrfs_file_extent_other_encoding(leaf, fi))
 957                 return 0;
 958
 959         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 960         if ((*start && *start != key.offset) || (*end && *end != extent_end))
 961                 return 0;
 962
 963         *start = key.offset;
 964         *end = extent_end;
 965         return 1;
 966 }
 967
 968 /*
 969  * Mark extent in the range start - end as written.
 970  *
 971  * This changes extent type from 'pre-allocated' to 'regular'. If only
 972  * part of extent is marked as written, the extent will be split into
 973  * two or three.
 974  */
 975 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
 976                               struct inode *inode, u64 start, u64 end)
 977 {
 978         struct btrfs_root *root = BTRFS_I(inode)->root;
 979         struct extent_buffer *leaf;
 980         struct btrfs_path *path;
 981         struct btrfs_file_extent_item *fi;
 982         struct btrfs_key key;
 983         struct btrfs_key new_key;
 984         u64 bytenr;
 985         u64 num_bytes;
 986         u64 extent_end;
 987         u64 orig_offset;
 988         u64 other_start;
 989         u64 other_end;
 990         u64 split;
 991         int del_nr = 0;
 992         int del_slot = 0;
 993         int recow;
 994         int ret;
 995         u64 ino = btrfs_ino(inode);
 996
 997         path = btrfs_alloc_path();
 998         if (!path)
 999                 return -ENOMEM;
1000 again:
1001         recow = 0;
1002         split = start;
1003         key.objectid = ino;
1004         key.type = BTRFS_EXTENT_DATA_KEY;
1005         key.offset = split;
1006
1007         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
1008         if (ret < 0)
1009                 goto out;
1010         if (ret > 0 && path->slots[0] > 0)
1011                 path->slots[0]--;
1012
1013         leaf = path->nodes[0];
1014         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
1015         BUG_ON(key.objectid != ino || key.type != BTRFS_EXTENT_DATA_KEY);
1016         fi = btrfs_item_ptr(leaf, path->slots[0],
1017                             struct btrfs_file_extent_item);
1018         BUG_ON(btrfs_file_extent_type(leaf, fi) !=
1019                BTRFS_FILE_EXTENT_PREALLOC);
1020         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
1021         BUG_ON(key.offset > start || extent_end < end);
1022
1023         bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1024         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1025         orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
1026         memcpy(&new_key, &key, sizeof(new_key));
1027
1028         if (start == key.offset && end < extent_end) {
1029                 other_start = 0;
1030                 other_end = start;
1031                 if (extent_mergeable(leaf, path->slots[0] - 1,
1032                                      ino, bytenr, orig_offset,
1033                                      &other_start, &other_end)) {
1034                         new_key.offset = end;
1035                         btrfs_set_item_key_safe(trans, root, path, &new_key);
1036                         fi = btrfs_item_ptr(leaf, path->slots[0],
1037                                             struct btrfs_file_extent_item);
1038                         btrfs_set_file_extent_generation(leaf, fi,
1039                                                          trans->transid);
1040                         btrfs_set_file_extent_num_bytes(leaf, fi,
1041                                                         extent_end - end);
1042                         btrfs_set_file_extent_offset(leaf, fi,
1043                                                      end - orig_offset);
1044                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
1045                                             struct btrfs_file_extent_item);
1046                         btrfs_set_file_extent_generation(leaf, fi,
1047                                                          trans->transid);
1048                         btrfs_set_file_extent_num_bytes(leaf, fi,
1049                                                         end - other_start);
1050                         btrfs_mark_buffer_dirty(leaf);
1051                         goto out;
1052                 }
1053         }
1054
1055         if (start > key.offset && end == extent_end) {
1056                 other_start = end;
1057                 other_end = 0;
1058                 if (extent_mergeable(leaf, path->slots[0] + 1,
1059                                      ino, bytenr, orig_offset,
1060                                      &other_start, &other_end)) {
1061                         fi = btrfs_item_ptr(leaf, path->slots[0],
1062                                             struct btrfs_file_extent_item);
1063                         btrfs_set_file_extent_num_bytes(leaf, fi,
1064                                                         start - key.offset);
1065                         btrfs_set_file_extent_generation(leaf, fi,
1066                                                          trans->transid);
1067                         path->slots[0]++;
1068                         new_key.offset = start;
1069                         btrfs_set_item_key_safe(trans, root, path, &new_key);
1070
1071                         fi = btrfs_item_ptr(leaf, path->slots[0],
1072                                             struct btrfs_file_extent_item);
1073                         btrfs_set_file_extent_generation(leaf, fi,
1074                                                          trans->transid);
1075                         btrfs_set_file_extent_num_bytes(leaf, fi,
1076                                                         other_end - start);
1077                         btrfs_set_file_extent_offset(leaf, fi,
1078                                                      start - orig_offset);
1079                         btrfs_mark_buffer_dirty(leaf);
1080                         goto out;
1081                 }
1082         }
1083
1084         while (start > key.offset || end < extent_end) {
1085                 if (key.offset == start)
1086                         split = end;
1087
1088                 new_key.offset = split;
1089                 ret = btrfs_duplicate_item(trans, root, path, &new_key);
1090                 if (ret == -EAGAIN) {
1091                         btrfs_release_path(path);
1092                         goto again;
1093                 }
1094                 if (ret < 0) {
1095                         btrfs_abort_transaction(trans, root, ret);
1096                         goto out;
1097                 }
1098
1099                 leaf = path->nodes[0];
1100                 fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
1101                                     struct btrfs_file_extent_item);
1102                 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
1103                 btrfs_set_file_extent_num_bytes(leaf, fi,
1104                                                 split - key.offset);
1105
1106                 fi = btrfs_item_ptr(leaf, path->slots[0],
1107                                     struct btrfs_file_extent_item);
1108
1109                 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
1110                 btrfs_set_file_extent_offset(leaf, fi, split - orig_offset);
1111                 btrfs_set_file_extent_num_bytes(leaf, fi,
1112                                                 extent_end - split);
1113                 btrfs_mark_buffer_dirty(leaf);
1114
1115                 ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
1116                                            root->root_key.objectid,
1117                                            ino, orig_offset, 0);
1118                 BUG_ON(ret); /* -ENOMEM */
1119
1120                 if (split == start) {
1121                         key.offset = start;
1122                 } else {
1123                         BUG_ON(start != key.offset);
1124                         path->slots[0]--;
1125                         extent_end = end;
1126                 }
1127                 recow = 1;
1128         }
1129
1130         other_start = end;
1131         other_end = 0;
1132         if (extent_mergeable(leaf, path->slots[0] + 1,
1133                              ino, bytenr, orig_offset,
1134                              &other_start, &other_end)) {
1135                 if (recow) {
1136                         btrfs_release_path(path);
1137                         goto again;
1138                 }
1139                 extent_end = other_end;
1140                 del_slot = path->slots[0] + 1;
1141                 del_nr++;
1142                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1143                                         0, root->root_key.objectid,
1144                                         ino, orig_offset, 0);
1145                 BUG_ON(ret); /* -ENOMEM */
1146         }
1147         other_start = 0;
1148         other_end = start;
1149         if (extent_mergeable(leaf, path->slots[0] - 1,
1150                              ino, bytenr, orig_offset,
1151                              &other_start, &other_end)) {
1152                 if (recow) {
1153                         btrfs_release_path(path);
1154                         goto again;
1155                 }
1156                 key.offset = other_start;
1157                 del_slot = path->slots[0];
1158                 del_nr++;
1159                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1160                                         0, root->root_key.objectid,
1161                                         ino, orig_offset, 0);
1162                 BUG_ON(ret); /* -ENOMEM */
1163         }
1164         if (del_nr == 0) {
1165                 fi = btrfs_item_ptr(leaf, path->slots[0],
1166                            struct btrfs_file_extent_item);
1167                 btrfs_set_file_extent_type(leaf, fi,
1168                                            BTRFS_FILE_EXTENT_REG);
1169                 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
1170                 btrfs_mark_buffer_dirty(leaf);
1171         } else {
1172                 fi = btrfs_item_ptr(leaf, del_slot - 1,
1173                            struct btrfs_file_extent_item);
1174                 btrfs_set_file_extent_type(leaf, fi,
1175                                            BTRFS_FILE_EXTENT_REG);
1176                 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
1177                 btrfs_set_file_extent_num_bytes(leaf, fi,
1178                                                 extent_end - key.offset);
1179                 btrfs_mark_buffer_dirty(leaf);
1180
1181                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
1182                 if (ret < 0) {
1183                         btrfs_abort_transaction(trans, root, ret);
1184                         goto out;
1185                 }
1186         }
1187 out:
1188         btrfs_free_path(path);
1189         return 0;
1190 }
1191
1192 /*
1193  * on error we return an unlocked page and the error value
1194  * on success we return a locked page and 0
1195  */
1196 static int prepare_uptodate_page(struct page *page, u64 pos,
1197                                  bool force_uptodate)
1198 {
1199         int ret = 0;
1200
1201         if (((pos & (PAGE_CACHE_SIZE - 1)) || force_uptodate) &&
1202             !PageUptodate(page)) {
1203                 ret = btrfs_readpage(NULL, page);
1204                 if (ret)
1205                         return ret;
1206                 lock_page(page);
1207                 if (!PageUptodate(page)) {
1208                         unlock_page(page);
1209                         return -EIO;
1210                 }
1211         }
1212         return 0;
1213 }
1214
1215 /*
1216  * this gets pages into the page cache and locks them down, it also properly
1217  * waits for data=ordered extents to finish before allowing the pages to be
1218  * modified.
1219  */
1220 static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
1221                          struct page **pages, size_t num_pages,
1222                          loff_t pos, unsigned long first_index,
1223                          size_t write_bytes, bool force_uptodate)
1224 {
1225         struct extent_state *cached_state = NULL;
1226         int i;
1227         unsigned long index = pos >> PAGE_CACHE_SHIFT;
1228         struct inode *inode = fdentry(file)->d_inode;
1229         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
1230         int err = 0;
1231         int faili = 0;
1232         u64 start_pos;
1233         u64 last_pos;
1234
1235         start_pos = pos & ~((u64)root->sectorsize - 1);
1236         last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
1237
1238 again:
1239         for (i = 0; i < num_pages; i++) {
1240                 pages[i] = find_or_create_page(inode->i_mapping, index + i,
1241                                                mask | __GFP_WRITE);
1242                 if (!pages[i]) {
1243                         faili = i - 1;
1244                         err = -ENOMEM;
1245                         goto fail;
1246                 }
1247
1248                 if (i == 0)
1249                         err = prepare_uptodate_page(pages[i], pos,
1250                                                     force_uptodate);
1251                 if (i == num_pages - 1)
1252                         err = prepare_uptodate_page(pages[i],
1253                                                     pos + write_bytes, false);
1254                 if (err) {
1255                         page_cache_release(pages[i]);
1256                         faili = i - 1;
1257                         goto fail;
1258                 }
1259                 wait_on_page_writeback(pages[i]);
1260         }
1261         err = 0;
1262         if (start_pos < inode->i_size) {
1263                 struct btrfs_ordered_extent *ordered;
1264                 lock_extent_bits(&BTRFS_I(inode)->io_tree,
1265                                  start_pos, last_pos - 1, 0, &cached_state);
1266                 ordered = btrfs_lookup_first_ordered_extent(inode,
1267                                                             last_pos - 1);
1268                 if (ordered &&
1269                     ordered->file_offset + ordered->len > start_pos &&
1270                     ordered->file_offset < last_pos) {
1271                         btrfs_put_ordered_extent(ordered);
1272                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1273                                              start_pos, last_pos - 1,
1274                                              &cached_state, GFP_NOFS);
1275                         for (i = 0; i < num_pages; i++) {
1276                                 unlock_page(pages[i]);
1277                                 page_cache_release(pages[i]);
1278                         }
1279                         btrfs_wait_ordered_range(inode, start_pos,
1280                                                  last_pos - start_pos);
1281                         goto again;
1282                 }
1283                 if (ordered)
1284                         btrfs_put_ordered_extent(ordered);
1285
1286                 clear_extent_bit(&BTRFS_I(inode)->io_tree, start_pos,
1287                                   last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC |
1288                                   EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG,
1289                                   0, 0, &cached_state, GFP_NOFS);
1290                 unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1291                                      start_pos, last_pos - 1, &cached_state,
1292                                      GFP_NOFS);
1293         }
1294         for (i = 0; i < num_pages; i++) {
1295                 if (clear_page_dirty_for_io(pages[i]))
1296                         account_page_redirty(pages[i]);
1297                 set_page_extent_mapped(pages[i]);
1298                 WARN_ON(!PageLocked(pages[i]));
1299         }
1300         return 0;
1301 fail:
1302         while (faili >= 0) {
1303                 unlock_page(pages[faili]);
1304                 page_cache_release(pages[faili]);
1305                 faili--;
1306         }
1307         return err;
1308
1309 }
1310
1311 static noinline ssize_t __btrfs_buffered_write(struct file *file,
1312                                                struct iov_iter *i,
1313                                                loff_t pos)
1314 {
1315         struct inode *inode = fdentry(file)->d_inode;
1316         struct btrfs_root *root = BTRFS_I(inode)->root;
1317         struct page **pages = NULL;
1318         unsigned long first_index;
1319         size_t num_written = 0;
1320         int nrptrs;
1321         int ret = 0;
1322         bool force_page_uptodate = false;
1323
1324         nrptrs = min((iov_iter_count(i) + PAGE_CACHE_SIZE - 1) /
1325                      PAGE_CACHE_SIZE, PAGE_CACHE_SIZE /
1326                      (sizeof(struct page *)));
1327         nrptrs = min(nrptrs, current->nr_dirtied_pause - current->nr_dirtied);
1328         nrptrs = max(nrptrs, 8);
1329         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
1330         if (!pages)
1331                 return -ENOMEM;
1332
1333         first_index = pos >> PAGE_CACHE_SHIFT;
1334
1335         while (iov_iter_count(i) > 0) {
1336                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
1337                 size_t write_bytes = min(iov_iter_count(i),
1338                                          nrptrs * (size_t)PAGE_CACHE_SIZE -
1339                                          offset);
1340                 size_t num_pages = (write_bytes + offset +
1341                                     PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1342                 size_t dirty_pages;
1343                 size_t copied;
1344
1345                 WARN_ON(num_pages > nrptrs);
1346
1347                 /*
1348                  * Fault pages before locking them in prepare_pages
1349                  * to avoid recursive lock
1350                  */
1351                 if (unlikely(iov_iter_fault_in_readable(i, write_bytes))) {
1352                         ret = -EFAULT;
1353                         break;
1354                 }
1355
1356                 ret = btrfs_delalloc_reserve_space(inode,
1357                                         num_pages << PAGE_CACHE_SHIFT);
1358                 if (ret)
1359                         break;
1360
1361                 /*
1362                  * This is going to setup the pages array with the number of
1363                  * pages we want, so we don't really need to worry about the
1364                  * contents of pages from loop to loop
1365                  */
1366                 ret = prepare_pages(root, file, pages, num_pages,
1367                                     pos, first_index, write_bytes,
1368                                     force_page_uptodate);
1369                 if (ret) {
1370                         btrfs_delalloc_release_space(inode,
1371                                         num_pages << PAGE_CACHE_SHIFT);
1372                         break;
1373                 }
1374
1375                 copied = btrfs_copy_from_user(pos, num_pages,
1376                                            write_bytes, pages, i);
1377
1378                 /*
1379                  * if we have trouble faulting in the pages, fall
1380                  * back to one page at a time
1381                  */
1382                 if (copied < write_bytes)
1383                         nrptrs = 1;
1384
1385                 if (copied == 0) {
1386                         force_page_uptodate = true;
1387                         dirty_pages = 0;
1388                 } else {
1389                         force_page_uptodate = false;
1390                         dirty_pages = (copied + offset +
1391                                        PAGE_CACHE_SIZE - 1) >>
1392                                        PAGE_CACHE_SHIFT;
1393                 }
1394
1395                 /*
1396                  * If we had a short copy we need to release the excess delaloc
1397                  * bytes we reserved.  We need to increment outstanding_extents
1398                  * because btrfs_delalloc_release_space will decrement it, but
1399                  * we still have an outstanding extent for the chunk we actually
1400                  * managed to copy.
1401                  */
1402                 if (num_pages > dirty_pages) {
1403                         if (copied > 0) {
1404                                 spin_lock(&BTRFS_I(inode)->lock);
1405                                 BTRFS_I(inode)->outstanding_extents++;
1406                                 spin_unlock(&BTRFS_I(inode)->lock);
1407                         }
1408                         btrfs_delalloc_release_space(inode,
1409                                         (num_pages - dirty_pages) <<
1410                                         PAGE_CACHE_SHIFT);
1411                 }
1412
1413                 if (copied > 0) {
1414                         ret = btrfs_dirty_pages(root, inode, pages,
1415                                                 dirty_pages, pos, copied,
1416                                                 NULL);
1417                         if (ret) {
1418                                 btrfs_delalloc_release_space(inode,
1419                                         dirty_pages << PAGE_CACHE_SHIFT);
1420                                 btrfs_drop_pages(pages, num_pages);
1421                                 break;
1422                         }
1423                 }
1424
1425                 btrfs_drop_pages(pages, num_pages);
1426
1427                 cond_resched();
1428
1429                 balance_dirty_pages_ratelimited_nr(inode->i_mapping,
1430                                                    dirty_pages);
1431                 if (dirty_pages < (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
1432                         btrfs_btree_balance_dirty(root);
1433
1434                 pos += copied;
1435                 num_written += copied;
1436         }
1437
1438         kfree(pages);
1439
1440         return num_written ? num_written : ret;
1441 }
1442
1443 static ssize_t __btrfs_direct_write(struct kiocb *iocb,
1444                                     const struct iovec *iov,
1445                                     unsigned long nr_segs, loff_t pos,
1446                                     loff_t *ppos, size_t count, size_t ocount)
1447 {
1448         struct file *file = iocb->ki_filp;
1449         struct iov_iter i;
1450         ssize_t written;
1451         ssize_t written_buffered;
1452         loff_t endbyte;
1453         int err;
1454
1455         written = generic_file_direct_write(iocb, iov, &nr_segs, pos, ppos,
1456                                             count, ocount);
1457
1458         if (written < 0 || written == count)
1459                 return written;
1460
1461         pos += written;
1462         count -= written;
1463         iov_iter_init(&i, iov, nr_segs, count, written);
1464         written_buffered = __btrfs_buffered_write(file, &i, pos);
1465         if (written_buffered < 0) {
1466                 err = written_buffered;
1467                 goto out;
1468         }
1469         endbyte = pos + written_buffered - 1;
1470         err = filemap_write_and_wait_range(file->f_mapping, pos, endbyte);
1471         if (err)
1472                 goto out;
1473         written += written_buffered;
1474         *ppos = pos + written_buffered;
1475         invalidate_mapping_pages(file->f_mapping, pos >> PAGE_CACHE_SHIFT,
1476                                  endbyte >> PAGE_CACHE_SHIFT);
1477 out:
1478         return written ? written : err;
1479 }
1480
1481 static void update_time_for_write(struct inode *inode)
1482 {
1483         struct timespec now;
1484
1485         if (IS_NOCMTIME(inode))
1486                 return;
1487
1488         now = current_fs_time(inode->i_sb);
1489         if (!timespec_equal(&inode->i_mtime, &now))
1490                 inode->i_mtime = now;
1491
1492         if (!timespec_equal(&inode->i_ctime, &now))
1493                 inode->i_ctime = now;
1494
1495         if (IS_I_VERSION(inode))
1496                 inode_inc_iversion(inode);
1497 }
1498
1499 static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
1500                                     const struct iovec *iov,
1501                                     unsigned long nr_segs, loff_t pos)
1502 {
1503         struct file *file = iocb->ki_filp;
1504         struct inode *inode = fdentry(file)->d_inode;
1505         struct btrfs_root *root = BTRFS_I(inode)->root;
1506         loff_t *ppos = &iocb->ki_pos;
1507         u64 start_pos;
1508         ssize_t num_written = 0;
1509         ssize_t err = 0;
1510         size_t count, ocount;
1511         bool sync = (file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host);
1512
1513         sb_start_write(inode->i_sb);
1514
1515         mutex_lock(&inode->i_mutex);
1516
1517         err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
1518         if (err) {
1519                 mutex_unlock(&inode->i_mutex);
1520                 goto out;
1521         }
1522         count = ocount;
1523
1524         current->backing_dev_info = inode->i_mapping->backing_dev_info;
1525         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
1526         if (err) {
1527                 mutex_unlock(&inode->i_mutex);
1528                 goto out;
1529         }
1530
1531         if (count == 0) {
1532                 mutex_unlock(&inode->i_mutex);
1533                 goto out;
1534         }
1535
1536         err = file_remove_suid(file);
1537         if (err) {
1538                 mutex_unlock(&inode->i_mutex);
1539                 goto out;
1540         }
1541
1542         /*
1543          * If BTRFS flips readonly due to some impossible error
1544          * (fs_info->fs_state now has BTRFS_SUPER_FLAG_ERROR),
1545          * although we have opened a file as writable, we have
1546          * to stop this write operation to ensure FS consistency.
1547          */
1548         if (test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state)) {
1549                 mutex_unlock(&inode->i_mutex);
1550                 err = -EROFS;
1551                 goto out;
1552         }
1553
1554         /*
1555          * We reserve space for updating the inode when we reserve space for the
1556          * extent we are going to write, so we will enospc out there.  We don't
1557          * need to start yet another transaction to update the inode as we will
1558          * update the inode when we finish writing whatever data we write.
1559          */
1560         update_time_for_write(inode);
1561
1562         start_pos = round_down(pos, root->sectorsize);
1563         if (start_pos > i_size_read(inode)) {
1564                 err = btrfs_cont_expand(inode, i_size_read(inode), start_pos);
1565                 if (err) {
1566                         mutex_unlock(&inode->i_mutex);
1567                         goto out;
1568                 }
1569         }
1570
1571         if (sync)
1572                 atomic_inc(&BTRFS_I(inode)->sync_writers);
1573
1574         if (unlikely(file->f_flags & O_DIRECT)) {
1575                 num_written = __btrfs_direct_write(iocb, iov, nr_segs,
1576                                                    pos, ppos, count, ocount);
1577         } else {
1578                 struct iov_iter i;
1579
1580                 iov_iter_init(&i, iov, nr_segs, count, num_written);
1581
1582                 num_written = __btrfs_buffered_write(file, &i, pos);
1583                 if (num_written > 0)
1584                         *ppos = pos + num_written;
1585         }
1586
1587         mutex_unlock(&inode->i_mutex);
1588
1589         /*
1590          * we want to make sure fsync finds this change
1591          * but we haven't joined a transaction running right now.
1592          *
1593          * Later on, someone is sure to update the inode and get the
1594          * real transid recorded.
1595          *
1596          * We set last_trans now to the fs_info generation + 1,
1597          * this will either be one more than the running transaction
1598          * or the generation used for the next transaction if there isn't
1599          * one running right now.
1600          *
1601          * We also have to set last_sub_trans to the current log transid,
1602          * otherwise subsequent syncs to a file that's been synced in this
1603          * transaction will appear to have already occured.
1604          */
1605         BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
1606         BTRFS_I(inode)->last_sub_trans = root->log_transid;
1607         if (num_written > 0 || num_written == -EIOCBQUEUED) {
1608                 err = generic_write_sync(file, pos, num_written);
1609                 if (err < 0 && num_written > 0)
1610                         num_written = err;
1611         }
1612
1613         if (sync)
1614                 atomic_dec(&BTRFS_I(inode)->sync_writers);
1615 out:
1616         sb_end_write(inode->i_sb);
1617         current->backing_dev_info = NULL;
1618         return num_written ? num_written : err;
1619 }
1620
1621 int btrfs_release_file(struct inode *inode, struct file *filp)
1622 {
1623         /*
1624          * ordered_data_close is set by settattr when we are about to truncate
1625          * a file from a non-zero size to a zero size.  This tries to
1626          * flush down new bytes that may have been written if the
1627          * application were using truncate to replace a file in place.
1628          */
1629         if (test_and_clear_bit(BTRFS_INODE_ORDERED_DATA_CLOSE,
1630                                &BTRFS_I(inode)->runtime_flags)) {
1631                 btrfs_add_ordered_operation(NULL, BTRFS_I(inode)->root, inode);
1632                 if (inode->i_size > BTRFS_ORDERED_OPERATIONS_FLUSH_LIMIT)
1633                         filemap_flush(inode->i_mapping);
1634         }
1635         if (filp->private_data)
1636                 btrfs_ioctl_trans_end(filp);
1637         return 0;
1638 }
1639
1640 /*
1641  * fsync call for both files and directories.  This logs the inode into
1642  * the tree log instead of forcing full commits whenever possible.
1643  *
1644  * It needs to call filemap_fdatawait so that all ordered extent updates are
1645  * in the metadata btree are up to date for copying to the log.
1646  *
1647  * It drops the inode mutex before doing the tree log commit.  This is an
1648  * important optimization for directories because holding the mutex prevents
1649  * new operations on the dir while we write to disk.
1650  */
1651 int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
1652 {
1653         struct dentry *dentry = file->f_path.dentry;
1654         struct inode *inode = dentry->d_inode;
1655         struct btrfs_root *root = BTRFS_I(inode)->root;
1656         int ret = 0;
1657         struct btrfs_trans_handle *trans;
1658         bool full_sync = 0;
1659
1660         trace_btrfs_sync_file(file, datasync);
1661
1662         /*
1663          * We write the dirty pages in the range and wait until they complete
1664          * out of the ->i_mutex. If so, we can flush the dirty pages by
1665          * multi-task, and make the performance up.  See
1666          * btrfs_wait_ordered_range for an explanation of the ASYNC check.
1667          */
1668         atomic_inc(&BTRFS_I(inode)->sync_writers);
1669         ret = filemap_fdatawrite_range(inode->i_mapping, start, end);
1670         if (!ret && test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
1671                              &BTRFS_I(inode)->runtime_flags))
1672                 ret = filemap_fdatawrite_range(inode->i_mapping, start, end);
1673         atomic_dec(&BTRFS_I(inode)->sync_writers);
1674         if (ret)
1675                 return ret;
1676
1677         mutex_lock(&inode->i_mutex);
1678
1679         /*
1680          * We flush the dirty pages again to avoid some dirty pages in the
1681          * range being left.
1682          */
1683         atomic_inc(&root->log_batch);
1684         full_sync = test_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
1685                              &BTRFS_I(inode)->runtime_flags);
1686         if (full_sync)
1687                 btrfs_wait_ordered_range(inode, start, end - start + 1);
1688         atomic_inc(&root->log_batch);
1689
1690         /*
1691          * check the transaction that last modified this inode
1692          * and see if its already been committed
1693          */
1694         if (!BTRFS_I(inode)->last_trans) {
1695                 mutex_unlock(&inode->i_mutex);
1696                 goto out;
1697         }
1698
1699         /*
1700          * if the last transaction that changed this file was before
1701          * the current transaction, we can bail out now without any
1702          * syncing
1703          */
1704         smp_mb();
1705         if (btrfs_inode_in_log(inode, root->fs_info->generation) ||
1706             BTRFS_I(inode)->last_trans <=
1707             root->fs_info->last_trans_committed) {
1708                 BTRFS_I(inode)->last_trans = 0;
1709
1710                 /*
1711                  * We'v had everything committed since the last time we were
1712                  * modified so clear this flag in case it was set for whatever
1713                  * reason, it's no longer relevant.
1714                  */
1715                 clear_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
1716                           &BTRFS_I(inode)->runtime_flags);
1717                 mutex_unlock(&inode->i_mutex);
1718                 goto out;
1719         }
1720
1721         /*
1722          * ok we haven't committed the transaction yet, lets do a commit
1723          */
1724         if (file->private_data)
1725                 btrfs_ioctl_trans_end(file);
1726
1727         trans = btrfs_start_transaction(root, 0);
1728         if (IS_ERR(trans)) {
1729                 ret = PTR_ERR(trans);
1730                 mutex_unlock(&inode->i_mutex);
1731                 goto out;
1732         }
1733
1734         ret = btrfs_log_dentry_safe(trans, root, dentry);
1735         if (ret < 0) {
1736                 mutex_unlock(&inode->i_mutex);
1737                 goto out;
1738         }
1739
1740         /* we've logged all the items and now have a consistent
1741          * version of the file in the log.  It is possible that
1742          * someone will come in and modify the file, but that's
1743          * fine because the log is consistent on disk, and we
1744          * have references to all of the file's extents
1745          *
1746          * It is possible that someone will come in and log the
1747          * file again, but that will end up using the synchronization
1748          * inside btrfs_sync_log to keep things safe.
1749          */
1750         mutex_unlock(&inode->i_mutex);
1751
1752         if (ret != BTRFS_NO_LOG_SYNC) {
1753                 if (ret > 0) {
1754                         /*
1755                          * If we didn't already wait for ordered extents we need
1756                          * to do that now.
1757                          */
1758                         if (!full_sync)
1759                                 btrfs_wait_ordered_range(inode, start,
1760                                                          end - start + 1);
1761                         ret = btrfs_commit_transaction(trans, root);
1762                 } else {
1763                         ret = btrfs_sync_log(trans, root);
1764                         if (ret == 0) {
1765                                 ret = btrfs_end_transaction(trans, root);
1766                         } else {
1767                                 if (!full_sync)
1768                                         btrfs_wait_ordered_range(inode, start,
1769                                                                  end -
1770                                                                  start + 1);
1771                                 ret = btrfs_commit_transaction(trans, root);
1772                         }
1773                 }
1774         } else {
1775                 ret = btrfs_end_transaction(trans, root);
1776         }
1777 out:
1778         return ret > 0 ? -EIO : ret;
1779 }
1780
1781 static const struct vm_operations_struct btrfs_file_vm_ops = {
1782         .fault          = filemap_fault,
1783         .page_mkwrite   = btrfs_page_mkwrite,
1784         .remap_pages    = generic_file_remap_pages,
1785 };
1786
1787 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
1788 {
1789         struct address_space *mapping = filp->f_mapping;
1790
1791         if (!mapping->a_ops->readpage)
1792                 return -ENOEXEC;
1793
1794         file_accessed(filp);
1795         vma->vm_ops = &btrfs_file_vm_ops;
1796
1797         return 0;
1798 }
1799
1800 static int hole_mergeable(struct inode *inode, struct extent_buffer *leaf,
1801                           int slot, u64 start, u64 end)
1802 {
1803         struct btrfs_file_extent_item *fi;
1804         struct btrfs_key key;
1805
1806         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
1807                 return 0;
1808
1809         btrfs_item_key_to_cpu(leaf, &key, slot);
1810         if (key.objectid != btrfs_ino(inode) ||
1811             key.type != BTRFS_EXTENT_DATA_KEY)
1812                 return 0;
1813
1814         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
1815
1816         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG)
1817                 return 0;
1818
1819         if (btrfs_file_extent_disk_bytenr(leaf, fi))
1820                 return 0;
1821
1822         if (key.offset == end)
1823                 return 1;
1824         if (key.offset + btrfs_file_extent_num_bytes(leaf, fi) == start)
1825                 return 1;
1826         return 0;
1827 }
1828
1829 static int fill_holes(struct btrfs_trans_handle *trans, struct inode *inode,
1830                       struct btrfs_path *path, u64 offset, u64 end)
1831 {
1832         struct btrfs_root *root = BTRFS_I(inode)->root;
1833         struct extent_buffer *leaf;
1834         struct btrfs_file_extent_item *fi;
1835         struct extent_map *hole_em;
1836         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
1837         struct btrfs_key key;
1838         int ret;
1839
1840         key.objectid = btrfs_ino(inode);
1841         key.type = BTRFS_EXTENT_DATA_KEY;
1842         key.offset = offset;
1843
1844
1845         ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
1846         if (ret < 0)
1847                 return ret;
1848         BUG_ON(!ret);
1849
1850         leaf = path->nodes[0];
1851         if (hole_mergeable(inode, leaf, path->slots[0]-1, offset, end)) {
1852                 u64 num_bytes;
1853
1854                 path->slots[0]--;
1855                 fi = btrfs_item_ptr(leaf, path->slots[0],
1856                                     struct btrfs_file_extent_item);
1857                 num_bytes = btrfs_file_extent_num_bytes(leaf, fi) +
1858                         end - offset;
1859                 btrfs_set_file_extent_num_bytes(leaf, fi, num_bytes);
1860                 btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
1861                 btrfs_set_file_extent_offset(leaf, fi, 0);
1862                 btrfs_mark_buffer_dirty(leaf);
1863                 goto out;
1864         }
1865
1866         if (hole_mergeable(inode, leaf, path->slots[0]+1, offset, end)) {
1867                 u64 num_bytes;
1868
1869                 path->slots[0]++;
1870                 key.offset = offset;
1871                 btrfs_set_item_key_safe(trans, root, path, &key);
1872                 fi = btrfs_item_ptr(leaf, path->slots[0],
1873                                     struct btrfs_file_extent_item);
1874                 num_bytes = btrfs_file_extent_num_bytes(leaf, fi) + end -
1875                         offset;
1876                 btrfs_set_file_extent_num_bytes(leaf, fi, num_bytes);
1877                 btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
1878                 btrfs_set_file_extent_offset(leaf, fi, 0);
1879                 btrfs_mark_buffer_dirty(leaf);
1880                 goto out;
1881         }
1882         btrfs_release_path(path);
1883
1884         ret = btrfs_insert_file_extent(trans, root, btrfs_ino(inode), offset,
1885                                        0, 0, end - offset, 0, end - offset,
1886                                        0, 0, 0);
1887         if (ret)
1888                 return ret;
1889
1890 out:
1891         btrfs_release_path(path);
1892
1893         hole_em = alloc_extent_map();
1894         if (!hole_em) {
1895                 btrfs_drop_extent_cache(inode, offset, end - 1, 0);
1896                 set_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
1897                         &BTRFS_I(inode)->runtime_flags);
1898         } else {
1899                 hole_em->start = offset;
1900                 hole_em->len = end - offset;
1901                 hole_em->orig_start = offset;
1902
1903                 hole_em->block_start = EXTENT_MAP_HOLE;
1904                 hole_em->block_len = 0;
1905                 hole_em->orig_block_len = 0;
1906                 hole_em->bdev = root->fs_info->fs_devices->latest_bdev;
1907                 hole_em->compress_type = BTRFS_COMPRESS_NONE;
1908                 hole_em->generation = trans->transid;
1909
1910                 do {
1911                         btrfs_drop_extent_cache(inode, offset, end - 1, 0);
1912                         write_lock(&em_tree->lock);
1913                         ret = add_extent_mapping(em_tree, hole_em);
1914                         if (!ret)
1915                                 list_move(&hole_em->list,
1916                                           &em_tree->modified_extents);
1917                         write_unlock(&em_tree->lock);
1918                 } while (ret == -EEXIST);
1919                 free_extent_map(hole_em);
1920                 if (ret)
1921                         set_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
1922                                 &BTRFS_I(inode)->runtime_flags);
1923         }
1924
1925         return 0;
1926 }
1927
1928 static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
1929 {
1930         struct btrfs_root *root = BTRFS_I(inode)->root;
1931         struct extent_state *cached_state = NULL;
1932         struct btrfs_path *path;
1933         struct btrfs_block_rsv *rsv;
1934         struct btrfs_trans_handle *trans;
1935         u64 lockstart = round_up(offset, BTRFS_I(inode)->root->sectorsize);
1936         u64 lockend = round_down(offset + len,
1937                                  BTRFS_I(inode)->root->sectorsize) - 1;
1938         u64 cur_offset = lockstart;
1939         u64 min_size = btrfs_calc_trunc_metadata_size(root, 1);
1940         u64 drop_end;
1941         int ret = 0;
1942         int err = 0;
1943         bool same_page = ((offset >> PAGE_CACHE_SHIFT) ==
1944                           ((offset + len - 1) >> PAGE_CACHE_SHIFT));
1945
1946         btrfs_wait_ordered_range(inode, offset, len);
1947
1948         mutex_lock(&inode->i_mutex);
1949         /*
1950          * We needn't truncate any page which is beyond the end of the file
1951          * because we are sure there is no data there.
1952          */
1953         /*
1954          * Only do this if we are in the same page and we aren't doing the
1955          * entire page.
1956          */
1957         if (same_page && len < PAGE_CACHE_SIZE) {
1958                 if (offset < round_up(inode->i_size, PAGE_CACHE_SIZE))
1959                         ret = btrfs_truncate_page(inode, offset, len, 0);
1960                 mutex_unlock(&inode->i_mutex);
1961                 return ret;
1962         }
1963
1964         /* zero back part of the first page */
1965         if (offset < round_up(inode->i_size, PAGE_CACHE_SIZE)) {
1966                 ret = btrfs_truncate_page(inode, offset, 0, 0);
1967                 if (ret) {
1968                         mutex_unlock(&inode->i_mutex);
1969                         return ret;
1970                 }
1971         }
1972
1973         /* zero the front end of the last page */
1974         if (offset + len < round_up(inode->i_size, PAGE_CACHE_SIZE)) {
1975                 ret = btrfs_truncate_page(inode, offset + len, 0, 1);
1976                 if (ret) {
1977                         mutex_unlock(&inode->i_mutex);
1978                         return ret;
1979                 }
1980         }
1981
1982         if (lockend < lockstart) {
1983                 mutex_unlock(&inode->i_mutex);
1984                 return 0;
1985         }
1986
1987         while (1) {
1988                 struct btrfs_ordered_extent *ordered;
1989
1990                 truncate_pagecache_range(inode, lockstart, lockend);
1991
1992                 lock_extent_bits(&BTRFS_I(inode)->io_tree, lockstart, lockend,
1993                                  0, &cached_state);
1994                 ordered = btrfs_lookup_first_ordered_extent(inode, lockend);
1995
1996                 /*
1997                  * We need to make sure we have no ordered extents in this range
1998                  * and nobody raced in and read a page in this range, if we did
1999                  * we need to try again.
2000                  */
2001                 if ((!ordered ||
2002                     (ordered->file_offset + ordered->len < lockstart ||
2003                      ordered->file_offset > lockend)) &&
2004                      !test_range_bit(&BTRFS_I(inode)->io_tree, lockstart,
2005                                      lockend, EXTENT_UPTODATE, 0,
2006                                      cached_state)) {
2007                         if (ordered)
2008                                 btrfs_put_ordered_extent(ordered);
2009                         break;
2010                 }
2011                 if (ordered)
2012                         btrfs_put_ordered_extent(ordered);
2013                 unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart,
2014                                      lockend, &cached_state, GFP_NOFS);
2015                 btrfs_wait_ordered_range(inode, lockstart,
2016                                          lockend - lockstart + 1);
2017         }
2018
2019         path = btrfs_alloc_path();
2020         if (!path) {
2021                 ret = -ENOMEM;
2022                 goto out;
2023         }
2024
2025         rsv = btrfs_alloc_block_rsv(root, BTRFS_BLOCK_RSV_TEMP);
2026         if (!rsv) {
2027                 ret = -ENOMEM;
2028                 goto out_free;
2029         }
2030         rsv->size = btrfs_calc_trunc_metadata_size(root, 1);
2031         rsv->failfast = 1;
2032
2033         /*
2034          * 1 - update the inode
2035          * 1 - removing the extents in the range
2036          * 1 - adding the hole extent
2037          */
2038         trans = btrfs_start_transaction(root, 3);
2039         if (IS_ERR(trans)) {
2040                 err = PTR_ERR(trans);
2041                 goto out_free;
2042         }
2043
2044         ret = btrfs_block_rsv_migrate(&root->fs_info->trans_block_rsv, rsv,
2045                                       min_size);
2046         BUG_ON(ret);
2047         trans->block_rsv = rsv;
2048
2049         while (cur_offset < lockend) {
2050                 ret = __btrfs_drop_extents(trans, root, inode, path,
2051                                            cur_offset, lockend + 1,
2052                                            &drop_end, 1);
2053                 if (ret != -ENOSPC)
2054                         break;
2055
2056                 trans->block_rsv = &root->fs_info->trans_block_rsv;
2057
2058                 ret = fill_holes(trans, inode, path, cur_offset, drop_end);
2059                 if (ret) {
2060                         err = ret;
2061                         break;
2062                 }
2063
2064                 cur_offset = drop_end;
2065
2066                 ret = btrfs_update_inode(trans, root, inode);
2067                 if (ret) {
2068                         err = ret;
2069                         break;
2070                 }
2071
2072                 btrfs_end_transaction(trans, root);
2073                 btrfs_btree_balance_dirty(root);
2074
2075                 trans = btrfs_start_transaction(root, 3);
2076                 if (IS_ERR(trans)) {
2077                         ret = PTR_ERR(trans);
2078                         trans = NULL;
2079                         break;
2080                 }
2081
2082                 ret = btrfs_block_rsv_migrate(&root->fs_info->trans_block_rsv,
2083                                               rsv, min_size);
2084                 BUG_ON(ret);    /* shouldn't happen */
2085                 trans->block_rsv = rsv;
2086         }
2087
2088         if (ret) {
2089                 err = ret;
2090                 goto out_trans;
2091         }
2092
2093         trans->block_rsv = &root->fs_info->trans_block_rsv;
2094         ret = fill_holes(trans, inode, path, cur_offset, drop_end);
2095         if (ret) {
2096                 err = ret;
2097                 goto out_trans;
2098         }
2099
2100 out_trans:
2101         if (!trans)
2102                 goto out_free;
2103
2104         inode_inc_iversion(inode);
2105         inode->i_mtime = inode->i_ctime = CURRENT_TIME;
2106
2107         trans->block_rsv = &root->fs_info->trans_block_rsv;
2108         ret = btrfs_update_inode(trans, root, inode);
2109         btrfs_end_transaction(trans, root);
2110         btrfs_btree_balance_dirty(root);
2111 out_free:
2112         btrfs_free_path(path);
2113         btrfs_free_block_rsv(root, rsv);
2114 out:
2115         unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
2116                              &cached_state, GFP_NOFS);
2117         mutex_unlock(&inode->i_mutex);
2118         if (ret && !err)
2119                 err = ret;
2120         return err;
2121 }
2122
2123 static long btrfs_fallocate(struct file *file, int mode,
2124                             loff_t offset, loff_t len)
2125 {
2126         struct inode *inode = file->f_path.dentry->d_inode;
2127         struct extent_state *cached_state = NULL;
2128         u64 cur_offset;
2129         u64 last_byte;
2130         u64 alloc_start;
2131         u64 alloc_end;
2132         u64 alloc_hint = 0;
2133         u64 locked_end;
2134         struct extent_map *em;
2135         int blocksize = BTRFS_I(inode)->root->sectorsize;
2136         int ret;
2137
2138         alloc_start = round_down(offset, blocksize);
2139         alloc_end = round_up(offset + len, blocksize);
2140
2141         /* Make sure we aren't being give some crap mode */
2142         if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
2143                 return -EOPNOTSUPP;
2144
2145         if (mode & FALLOC_FL_PUNCH_HOLE)
2146                 return btrfs_punch_hole(inode, offset, len);
2147
2148         /*
2149          * Make sure we have enough space before we do the
2150          * allocation.
2151          */
2152         ret = btrfs_check_data_free_space(inode, alloc_end - alloc_start);
2153         if (ret)
2154                 return ret;
2155
2156         /*
2157          * wait for ordered IO before we have any locks.  We'll loop again
2158          * below with the locks held.
2159          */
2160         btrfs_wait_ordered_range(inode, alloc_start, alloc_end - alloc_start);
2161
2162         mutex_lock(&inode->i_mutex);
2163         ret = inode_newsize_ok(inode, alloc_end);
2164         if (ret)
2165                 goto out;
2166
2167         if (alloc_start > inode->i_size) {
2168                 ret = btrfs_cont_expand(inode, i_size_read(inode),
2169                                         alloc_start);
2170                 if (ret)
2171                         goto out;
2172         }
2173
2174         locked_end = alloc_end - 1;
2175         while (1) {
2176                 struct btrfs_ordered_extent *ordered;
2177
2178                 /* the extent lock is ordered inside the running
2179                  * transaction
2180                  */
2181                 lock_extent_bits(&BTRFS_I(inode)->io_tree, alloc_start,
2182                                  locked_end, 0, &cached_state);
2183                 ordered = btrfs_lookup_first_ordered_extent(inode,
2184                                                             alloc_end - 1);
2185                 if (ordered &&
2186                     ordered->file_offset + ordered->len > alloc_start &&
2187                     ordered->file_offset < alloc_end) {
2188                         btrfs_put_ordered_extent(ordered);
2189                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
2190                                              alloc_start, locked_end,
2191                                              &cached_state, GFP_NOFS);
2192                         /*
2193                          * we can't wait on the range with the transaction
2194                          * running or with the extent lock held
2195                          */
2196                         btrfs_wait_ordered_range(inode, alloc_start,
2197                                                  alloc_end - alloc_start);
2198                 } else {
2199                         if (ordered)
2200                                 btrfs_put_ordered_extent(ordered);
2201                         break;
2202                 }
2203         }
2204
2205         cur_offset = alloc_start;
2206         while (1) {
2207                 u64 actual_end;
2208
2209                 em = btrfs_get_extent(inode, NULL, 0, cur_offset,
2210                                       alloc_end - cur_offset, 0);
2211                 if (IS_ERR_OR_NULL(em)) {
2212                         if (!em)
2213                                 ret = -ENOMEM;
2214                         else
2215                                 ret = PTR_ERR(em);
2216                         break;
2217                 }
2218                 last_byte = min(extent_map_end(em), alloc_end);
2219                 actual_end = min_t(u64, extent_map_end(em), offset + len);
2220                 last_byte = ALIGN(last_byte, blocksize);
2221
2222                 if (em->block_start == EXTENT_MAP_HOLE ||
2223                     (cur_offset >= inode->i_size &&
2224                      !test_bit(EXTENT_FLAG_PREALLOC, &em->flags))) {
2225                         ret = btrfs_prealloc_file_range(inode, mode, cur_offset,
2226                                                         last_byte - cur_offset,
2227                                                         1 << inode->i_blkbits,
2228                                                         offset + len,
2229                                                         &alloc_hint);
2230
2231                         if (ret < 0) {
2232                                 free_extent_map(em);
2233                                 break;
2234                         }
2235                 } else if (actual_end > inode->i_size &&
2236                            !(mode & FALLOC_FL_KEEP_SIZE)) {
2237                         /*
2238                          * We didn't need to allocate any more space, but we
2239                          * still extended the size of the file so we need to
2240                          * update i_size.
2241                          */
2242                         inode->i_ctime = CURRENT_TIME;
2243                         i_size_write(inode, actual_end);
2244                         btrfs_ordered_update_i_size(inode, actual_end, NULL);
2245                 }
2246                 free_extent_map(em);
2247
2248                 cur_offset = last_byte;
2249                 if (cur_offset >= alloc_end) {
2250                         ret = 0;
2251                         break;
2252                 }
2253         }
2254         unlock_extent_cached(&BTRFS_I(inode)->io_tree, alloc_start, locked_end,
2255                              &cached_state, GFP_NOFS);
2256 out:
2257         mutex_unlock(&inode->i_mutex);
2258         /* Let go of our reservation. */
2259         btrfs_free_reserved_data_space(inode, alloc_end - alloc_start);
2260         return ret;
2261 }
2262
2263 static int find_desired_extent(struct inode *inode, loff_t *offset, int origin)
2264 {
2265         struct btrfs_root *root = BTRFS_I(inode)->root;
2266         struct extent_map *em;
2267         struct extent_state *cached_state = NULL;
2268         u64 lockstart = *offset;
2269         u64 lockend = i_size_read(inode);
2270         u64 start = *offset;
2271         u64 orig_start = *offset;
2272         u64 len = i_size_read(inode);
2273         u64 last_end = 0;
2274         int ret = 0;
2275
2276         lockend = max_t(u64, root->sectorsize, lockend);
2277         if (lockend <= lockstart)
2278                 lockend = lockstart + root->sectorsize;
2279
2280         lockend--;
2281         len = lockend - lockstart + 1;
2282
2283         len = max_t(u64, len, root->sectorsize);
2284         if (inode->i_size == 0)
2285                 return -ENXIO;
2286
2287         lock_extent_bits(&BTRFS_I(inode)->io_tree, lockstart, lockend, 0,
2288                          &cached_state);
2289
2290         /*
2291          * Delalloc is such a pain.  If we have a hole and we have pending
2292          * delalloc for a portion of the hole we will get back a hole that
2293          * exists for the entire range since it hasn't been actually written
2294          * yet.  So to take care of this case we need to look for an extent just
2295          * before the position we want in case there is outstanding delalloc
2296          * going on here.
2297          */
2298         if (origin == SEEK_HOLE && start != 0) {
2299                 if (start <= root->sectorsize)
2300                         em = btrfs_get_extent_fiemap(inode, NULL, 0, 0,
2301                                                      root->sectorsize, 0);
2302                 else
2303                         em = btrfs_get_extent_fiemap(inode, NULL, 0,
2304                                                      start - root->sectorsize,
2305                                                      root->sectorsize, 0);
2306                 if (IS_ERR(em)) {
2307                         ret = PTR_ERR(em);
2308                         goto out;
2309                 }
2310                 last_end = em->start + em->len;
2311                 if (em->block_start == EXTENT_MAP_DELALLOC)
2312                         last_end = min_t(u64, last_end, inode->i_size);
2313                 free_extent_map(em);
2314         }
2315
2316         while (1) {
2317                 em = btrfs_get_extent_fiemap(inode, NULL, 0, start, len, 0);
2318                 if (IS_ERR(em)) {
2319                         ret = PTR_ERR(em);
2320                         break;
2321                 }
2322
2323                 if (em->block_start == EXTENT_MAP_HOLE) {
2324                         if (test_bit(EXTENT_FLAG_VACANCY, &em->flags)) {
2325                                 if (last_end <= orig_start) {
2326                                         free_extent_map(em);
2327                                         ret = -ENXIO;
2328                                         break;
2329                                 }
2330                         }
2331
2332                         if (origin == SEEK_HOLE) {
2333                                 *offset = start;
2334                                 free_extent_map(em);
2335                                 break;
2336                         }
2337                 } else {
2338                         if (origin == SEEK_DATA) {
2339                                 if (em->block_start == EXTENT_MAP_DELALLOC) {
2340                                         if (start >= inode->i_size) {
2341                                                 free_extent_map(em);
2342                                                 ret = -ENXIO;
2343                                                 break;
2344                                         }
2345                                 }
2346
2347                                 if (!test_bit(EXTENT_FLAG_PREALLOC,
2348                                               &em->flags)) {
2349                                         *offset = start;
2350                                         free_extent_map(em);
2351                                         break;
2352                                 }
2353                         }
2354                 }
2355
2356                 start = em->start + em->len;
2357                 last_end = em->start + em->len;
2358
2359                 if (em->block_start == EXTENT_MAP_DELALLOC)
2360                         last_end = min_t(u64, last_end, inode->i_size);
2361
2362                 if (test_bit(EXTENT_FLAG_VACANCY, &em->flags)) {
2363                         free_extent_map(em);
2364                         ret = -ENXIO;
2365                         break;
2366                 }
2367                 free_extent_map(em);
2368                 cond_resched();
2369         }
2370         if (!ret)
2371                 *offset = min(*offset, inode->i_size);
2372 out:
2373         unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
2374                              &cached_state, GFP_NOFS);
2375         return ret;
2376 }
2377
2378 static loff_t btrfs_file_llseek(struct file *file, loff_t offset, int origin)
2379 {
2380         struct inode *inode = file->f_mapping->host;
2381         int ret;
2382
2383         mutex_lock(&inode->i_mutex);
2384         switch (origin) {
2385         case SEEK_END:
2386         case SEEK_CUR:
2387                 offset = generic_file_llseek(file, offset, origin);
2388                 goto out;
2389         case SEEK_DATA:
2390         case SEEK_HOLE:
2391                 if (offset >= i_size_read(inode)) {
2392                         mutex_unlock(&inode->i_mutex);
2393                         return -ENXIO;
2394                 }
2395
2396                 ret = find_desired_extent(inode, &offset, origin);
2397                 if (ret) {
2398                         mutex_unlock(&inode->i_mutex);
2399                         return ret;
2400                 }
2401         }
2402
2403         if (offset < 0 && !(file->f_mode & FMODE_UNSIGNED_OFFSET)) {
2404                 offset = -EINVAL;
2405                 goto out;
2406         }
2407         if (offset > inode->i_sb->s_maxbytes) {
2408                 offset = -EINVAL;
2409                 goto out;
2410         }
2411
2412         /* Special lock needed here? */
2413         if (offset != file->f_pos) {
2414                 file->f_pos = offset;
2415                 file->f_version = 0;
2416         }
2417 out:
2418         mutex_unlock(&inode->i_mutex);
2419         return offset;
2420 }
2421
2422 const struct file_operations btrfs_file_operations = {
2423         .llseek         = btrfs_file_llseek,
2424         .read           = do_sync_read,
2425         .write          = do_sync_write,
2426         .aio_read       = generic_file_aio_read,
2427         .splice_read    = generic_file_splice_read,
2428         .aio_write      = btrfs_file_aio_write,
2429         .mmap           = btrfs_file_mmap,
2430         .open           = generic_file_open,
2431         .release        = btrfs_release_file,
2432         .fsync          = btrfs_sync_file,
2433         .fallocate      = btrfs_fallocate,
2434         .unlocked_ioctl = btrfs_ioctl,
2435 #ifdef CONFIG_COMPAT
2436         .compat_ioctl   = btrfs_ioctl,
2437 #endif
2438 };
2439
2440 void btrfs_auto_defrag_exit(void)
2441 {
2442         if (btrfs_inode_defrag_cachep)
2443                 kmem_cache_destroy(btrfs_inode_defrag_cachep);
2444 }
2445
2446 int btrfs_auto_defrag_init(void)
2447 {
2448         btrfs_inode_defrag_cachep = kmem_cache_create("btrfs_inode_defrag",
2449                                         sizeof(struct inode_defrag), 0,
2450                                         SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD,
2451                                         NULL);
2452         if (!btrfs_inode_defrag_cachep)
2453                 return -ENOMEM;
2454
2455         return 0;
2456 }