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 "ctree.h"
  34 #include "disk-io.h"
  35 #include "transaction.h"
  36 #include "btrfs_inode.h"
  37 #include "ioctl.h"
  38 #include "print-tree.h"
  39 #include "tree-log.h"
  40 #include "locking.h"
  41 #include "compat.h"
  42
  43 /*
  44  * when auto defrag is enabled we
  45  * queue up these defrag structs to remember which
  46  * inodes need defragging passes
  47  */
  48 struct inode_defrag {
  49         struct rb_node rb_node;
  50         /* objectid */
  51         u64 ino;
  52         /*
  53          * transid where the defrag was added, we search for
  54          * extents newer than this
  55          */
  56         u64 transid;
  57
  58         /* root objectid */
  59         u64 root;
  60
  61         /* last offset we were able to defrag */
  62         u64 last_offset;
  63
  64         /* if we've wrapped around back to zero once already */
  65         int cycled;
  66 };
  67
  68 /* pop a record for an inode into the defrag tree.  The lock
  69  * must be held already
  70  *
  71  * If you're inserting a record for an older transid than an
  72  * existing record, the transid already in the tree is lowered
  73  *
  74  * If an existing record is found the defrag item you
  75  * pass in is freed
  76  */
  77 static void __btrfs_add_inode_defrag(struct inode *inode,
  78                                     struct inode_defrag *defrag)
  79 {
  80         struct btrfs_root *root = BTRFS_I(inode)->root;
  81         struct inode_defrag *entry;
  82         struct rb_node **p;
  83         struct rb_node *parent = NULL;
  84
  85         p = &root->fs_info->defrag_inodes.rb_node;
  86         while (*p) {
  87                 parent = *p;
  88                 entry = rb_entry(parent, struct inode_defrag, rb_node);
  89
  90                 if (defrag->ino < entry->ino)
  91                         p = &parent->rb_left;
  92                 else if (defrag->ino > entry->ino)
  93                         p = &parent->rb_right;
  94                 else {
  95                         /* if we're reinserting an entry for
  96                          * an old defrag run, make sure to
  97                          * lower the transid of our existing record
  98                          */
  99                         if (defrag->transid < entry->transid)
 100                                 entry->transid = defrag->transid;
 101                         if (defrag->last_offset > entry->last_offset)
 102                                 entry->last_offset = defrag->last_offset;
 103                         goto exists;
 104                 }
 105         }
 106         BTRFS_I(inode)->in_defrag = 1;
 107         rb_link_node(&defrag->rb_node, parent, p);
 108         rb_insert_color(&defrag->rb_node, &root->fs_info->defrag_inodes);
 109         return;
 110
 111 exists:
 112         kfree(defrag);
 113         return;
 114
 115 }
 116
 117 /*
 118  * insert a defrag record for this inode if auto defrag is
 119  * enabled
 120  */
 121 int btrfs_add_inode_defrag(struct btrfs_trans_handle *trans,
 122                            struct inode *inode)
 123 {
 124         struct btrfs_root *root = BTRFS_I(inode)->root;
 125         struct inode_defrag *defrag;
 126         u64 transid;
 127
 128         if (!btrfs_test_opt(root, AUTO_DEFRAG))
 129                 return 0;
 130
 131         if (btrfs_fs_closing(root->fs_info))
 132                 return 0;
 133
 134         if (BTRFS_I(inode)->in_defrag)
 135                 return 0;
 136
 137         if (trans)
 138                 transid = trans->transid;
 139         else
 140                 transid = BTRFS_I(inode)->root->last_trans;
 141
 142         defrag = kzalloc(sizeof(*defrag), GFP_NOFS);
 143         if (!defrag)
 144                 return -ENOMEM;
 145
 146         defrag->ino = btrfs_ino(inode);
 147         defrag->transid = transid;
 148         defrag->root = root->root_key.objectid;
 149
 150         spin_lock(&root->fs_info->defrag_inodes_lock);
 151         if (!BTRFS_I(inode)->in_defrag)
 152                 __btrfs_add_inode_defrag(inode, defrag);
 153         spin_unlock(&root->fs_info->defrag_inodes_lock);
 154         return 0;
 155 }
 156
 157 /*
 158  * must be called with the defrag_inodes lock held
 159  */
 160 struct inode_defrag *btrfs_find_defrag_inode(struct btrfs_fs_info *info, u64 ino,
 161                                              struct rb_node **next)
 162 {
 163         struct inode_defrag *entry = NULL;
 164         struct rb_node *p;
 165         struct rb_node *parent = NULL;
 166
 167         p = info->defrag_inodes.rb_node;
 168         while (p) {
 169                 parent = p;
 170                 entry = rb_entry(parent, struct inode_defrag, rb_node);
 171
 172                 if (ino < entry->ino)
 173                         p = parent->rb_left;
 174                 else if (ino > entry->ino)
 175                         p = parent->rb_right;
 176                 else
 177                         return entry;
 178         }
 179
 180         if (next) {
 181                 while (parent && ino > entry->ino) {
 182                         parent = rb_next(parent);
 183                         entry = rb_entry(parent, struct inode_defrag, rb_node);
 184                 }
 185                 *next = parent;
 186         }
 187         return NULL;
 188 }
 189
 190 /*
 191  * run through the list of inodes in the FS that need
 192  * defragging
 193  */
 194 int btrfs_run_defrag_inodes(struct btrfs_fs_info *fs_info)
 195 {
 196         struct inode_defrag *defrag;
 197         struct btrfs_root *inode_root;
 198         struct inode *inode;
 199         struct rb_node *n;
 200         struct btrfs_key key;
 201         struct btrfs_ioctl_defrag_range_args range;
 202         u64 first_ino = 0;
 203         int num_defrag;
 204         int defrag_batch = 1024;
 205
 206         memset(&range, 0, sizeof(range));
 207         range.len = (u64)-1;
 208
 209         atomic_inc(&fs_info->defrag_running);
 210         spin_lock(&fs_info->defrag_inodes_lock);
 211         while(1) {
 212                 n = NULL;
 213
 214                 /* find an inode to defrag */
 215                 defrag = btrfs_find_defrag_inode(fs_info, first_ino, &n);
 216                 if (!defrag) {
 217                         if (n)
 218                                 defrag = rb_entry(n, struct inode_defrag, rb_node);
 219                         else if (first_ino) {
 220                                 first_ino = 0;
 221                                 continue;
 222                         } else {
 223                                 break;
 224                         }
 225                 }
 226
 227                 /* remove it from the rbtree */
 228                 first_ino = defrag->ino + 1;
 229                 rb_erase(&defrag->rb_node, &fs_info->defrag_inodes);
 230
 231                 if (btrfs_fs_closing(fs_info))
 232                         goto next_free;
 233
 234                 spin_unlock(&fs_info->defrag_inodes_lock);
 235
 236                 /* get the inode */
 237                 key.objectid = defrag->root;
 238                 btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
 239                 key.offset = (u64)-1;
 240                 inode_root = btrfs_read_fs_root_no_name(fs_info, &key);
 241                 if (IS_ERR(inode_root))
 242                         goto next;
 243
 244                 key.objectid = defrag->ino;
 245                 btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
 246                 key.offset = 0;
 247
 248                 inode = btrfs_iget(fs_info->sb, &key, inode_root, NULL);
 249                 if (IS_ERR(inode))
 250                         goto next;
 251
 252                 /* do a chunk of defrag */
 253                 BTRFS_I(inode)->in_defrag = 0;
 254                 range.start = defrag->last_offset;
 255                 num_defrag = btrfs_defrag_file(inode, NULL, &range, defrag->transid,
 256                                                defrag_batch);
 257                 /*
 258                  * if we filled the whole defrag batch, there
 259                  * must be more work to do.  Queue this defrag
 260                  * again
 261                  */
 262                 if (num_defrag == defrag_batch) {
 263                         defrag->last_offset = range.start;
 264                         __btrfs_add_inode_defrag(inode, defrag);
 265                         /*
 266                          * we don't want to kfree defrag, we added it back to
 267                          * the rbtree
 268                          */
 269                         defrag = NULL;
 270                 } else if (defrag->last_offset && !defrag->cycled) {
 271                         /*
 272                          * we didn't fill our defrag batch, but
 273                          * we didn't start at zero.  Make sure we loop
 274                          * around to the start of the file.
 275                          */
 276                         defrag->last_offset = 0;
 277                         defrag->cycled = 1;
 278                         __btrfs_add_inode_defrag(inode, defrag);
 279                         defrag = NULL;
 280                 }
 281
 282                 iput(inode);
 283 next:
 284                 spin_lock(&fs_info->defrag_inodes_lock);
 285 next_free:
 286                 kfree(defrag);
 287         }
 288         spin_unlock(&fs_info->defrag_inodes_lock);
 289
 290         atomic_dec(&fs_info->defrag_running);
 291
 292         /*
 293          * during unmount, we use the transaction_wait queue to
 294          * wait for the defragger to stop
 295          */
 296         wake_up(&fs_info->transaction_wait);
 297         return 0;
 298 }
 299
 300 /* simple helper to fault in pages and copy.  This should go away
 301  * and be replaced with calls into generic code.
 302  */
 303 static noinline int btrfs_copy_from_user(loff_t pos, int num_pages,
 304                                          size_t write_bytes,
 305                                          struct page **prepared_pages,
 306                                          struct iov_iter *i)
 307 {
 308         size_t copied = 0;
 309         size_t total_copied = 0;
 310         int pg = 0;
 311         int offset = pos & (PAGE_CACHE_SIZE - 1);
 312
 313         while (write_bytes > 0) {
 314                 size_t count = min_t(size_t,
 315                                      PAGE_CACHE_SIZE - offset, write_bytes);
 316                 struct page *page = prepared_pages[pg];
 317                 /*
 318                  * Copy data from userspace to the current page
 319                  *
 320                  * Disable pagefault to avoid recursive lock since
 321                  * the pages are already locked
 322                  */
 323                 pagefault_disable();
 324                 copied = iov_iter_copy_from_user_atomic(page, i, offset, count);
 325                 pagefault_enable();
 326
 327                 /* Flush processor's dcache for this page */
 328                 flush_dcache_page(page);
 329
 330                 /*
 331                  * if we get a partial write, we can end up with
 332                  * partially up to date pages.  These add
 333                  * a lot of complexity, so make sure they don't
 334                  * happen by forcing this copy to be retried.
 335                  *
 336                  * The rest of the btrfs_file_write code will fall
 337                  * back to page at a time copies after we return 0.
 338                  */
 339                 if (!PageUptodate(page) && copied < count)
 340                         copied = 0;
 341
 342                 iov_iter_advance(i, copied);
 343                 write_bytes -= copied;
 344                 total_copied += copied;
 345
 346                 /* Return to btrfs_file_aio_write to fault page */
 347                 if (unlikely(copied == 0))
 348                         break;
 349
 350                 if (unlikely(copied < PAGE_CACHE_SIZE - offset)) {
 351                         offset += copied;
 352                 } else {
 353                         pg++;
 354                         offset = 0;
 355                 }
 356         }
 357         return total_copied;
 358 }
 359
 360 /*
 361  * unlocks pages after btrfs_file_write is done with them
 362  */
 363 void btrfs_drop_pages(struct page **pages, size_t num_pages)
 364 {
 365         size_t i;
 366         for (i = 0; i < num_pages; i++) {
 367                 /* page checked is some magic around finding pages that
 368                  * have been modified without going through btrfs_set_page_dirty
 369                  * clear it here
 370                  */
 371                 ClearPageChecked(pages[i]);
 372                 unlock_page(pages[i]);
 373                 mark_page_accessed(pages[i]);
 374                 page_cache_release(pages[i]);
 375         }
 376 }
 377
 378 /*
 379  * after copy_from_user, pages need to be dirtied and we need to make
 380  * sure holes are created between the current EOF and the start of
 381  * any next extents (if required).
 382  *
 383  * this also makes the decision about creating an inline extent vs
 384  * doing real data extents, marking pages dirty and delalloc as required.
 385  */
 386 int btrfs_dirty_pages(struct btrfs_root *root, struct inode *inode,
 387                       struct page **pages, size_t num_pages,
 388                       loff_t pos, size_t write_bytes,
 389                       struct extent_state **cached)
 390 {
 391         int err = 0;
 392         int i;
 393         u64 num_bytes;
 394         u64 start_pos;
 395         u64 end_of_last_block;
 396         u64 end_pos = pos + write_bytes;
 397         loff_t isize = i_size_read(inode);
 398
 399         start_pos = pos & ~((u64)root->sectorsize - 1);
 400         num_bytes = (write_bytes + pos - start_pos +
 401                     root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
 402
 403         end_of_last_block = start_pos + num_bytes - 1;
 404         err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block,
 405                                         cached);
 406         if (err)
 407                 return err;
 408
 409         for (i = 0; i < num_pages; i++) {
 410                 struct page *p = pages[i];
 411                 SetPageUptodate(p);
 412                 ClearPageChecked(p);
 413                 set_page_dirty(p);
 414         }
 415
 416         /*
 417          * we've only changed i_size in ram, and we haven't updated
 418          * the disk i_size.  There is no need to log the inode
 419          * at this time.
 420          */
 421         if (end_pos > isize)
 422                 i_size_write(inode, end_pos);
 423         return 0;
 424 }
 425
 426 /*
 427  * this drops all the extents in the cache that intersect the range
 428  * [start, end].  Existing extents are split as required.
 429  */
 430 int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
 431                             int skip_pinned)
 432 {
 433         struct extent_map *em;
 434         struct extent_map *split = NULL;
 435         struct extent_map *split2 = NULL;
 436         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
 437         u64 len = end - start + 1;
 438         int ret;
 439         int testend = 1;
 440         unsigned long flags;
 441         int compressed = 0;
 442
 443         WARN_ON(end < start);
 444         if (end == (u64)-1) {
 445                 len = (u64)-1;
 446                 testend = 0;
 447         }
 448         while (1) {
 449                 if (!split)
 450                         split = alloc_extent_map();
 451                 if (!split2)
 452                         split2 = alloc_extent_map();
 453                 BUG_ON(!split || !split2);
 454
 455                 write_lock(&em_tree->lock);
 456                 em = lookup_extent_mapping(em_tree, start, len);
 457                 if (!em) {
 458                         write_unlock(&em_tree->lock);
 459                         break;
 460                 }
 461                 flags = em->flags;
 462                 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
 463                         if (testend && em->start + em->len >= start + len) {
 464                                 free_extent_map(em);
 465                                 write_unlock(&em_tree->lock);
 466                                 break;
 467                         }
 468                         start = em->start + em->len;
 469                         if (testend)
 470                                 len = start + len - (em->start + em->len);
 471                         free_extent_map(em);
 472                         write_unlock(&em_tree->lock);
 473                         continue;
 474                 }
 475                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 476                 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
 477                 remove_extent_mapping(em_tree, em);
 478
 479                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 480                     em->start < start) {
 481                         split->start = em->start;
 482                         split->len = start - em->start;
 483                         split->orig_start = em->orig_start;
 484                         split->block_start = em->block_start;
 485
 486                         if (compressed)
 487                                 split->block_len = em->block_len;
 488                         else
 489                                 split->block_len = split->len;
 490
 491                         split->bdev = em->bdev;
 492                         split->flags = flags;
 493                         split->compress_type = em->compress_type;
 494                         ret = add_extent_mapping(em_tree, split);
 495                         BUG_ON(ret);
 496                         free_extent_map(split);
 497                         split = split2;
 498                         split2 = NULL;
 499                 }
 500                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 501                     testend && em->start + em->len > start + len) {
 502                         u64 diff = start + len - em->start;
 503
 504                         split->start = start + len;
 505                         split->len = em->start + em->len - (start + len);
 506                         split->bdev = em->bdev;
 507                         split->flags = flags;
 508                         split->compress_type = em->compress_type;
 509
 510                         if (compressed) {
 511                                 split->block_len = em->block_len;
 512                                 split->block_start = em->block_start;
 513                                 split->orig_start = em->orig_start;
 514                         } else {
 515                                 split->block_len = split->len;
 516                                 split->block_start = em->block_start + diff;
 517                                 split->orig_start = split->start;
 518                         }
 519
 520                         ret = add_extent_mapping(em_tree, split);
 521                         BUG_ON(ret);
 522                         free_extent_map(split);
 523                         split = NULL;
 524                 }
 525                 write_unlock(&em_tree->lock);
 526
 527                 /* once for us */
 528                 free_extent_map(em);
 529                 /* once for the tree*/
 530                 free_extent_map(em);
 531         }
 532         if (split)
 533                 free_extent_map(split);
 534         if (split2)
 535                 free_extent_map(split2);
 536         return 0;
 537 }
 538
 539 /*
 540  * this is very complex, but the basic idea is to drop all extents
 541  * in the range start - end.  hint_block is filled in with a block number
 542  * that would be a good hint to the block allocator for this file.
 543  *
 544  * If an extent intersects the range but is not entirely inside the range
 545  * it is either truncated or split.  Anything entirely inside the range
 546  * is deleted from the tree.
 547  */
 548 int btrfs_drop_extents(struct btrfs_trans_handle *trans, struct inode *inode,
 549                        u64 start, u64 end, u64 *hint_byte, int drop_cache)
 550 {
 551         struct btrfs_root *root = BTRFS_I(inode)->root;
 552         struct extent_buffer *leaf;
 553         struct btrfs_file_extent_item *fi;
 554         struct btrfs_path *path;
 555         struct btrfs_key key;
 556         struct btrfs_key new_key;
 557         u64 ino = btrfs_ino(inode);
 558         u64 search_start = start;
 559         u64 disk_bytenr = 0;
 560         u64 num_bytes = 0;
 561         u64 extent_offset = 0;
 562         u64 extent_end = 0;
 563         int del_nr = 0;
 564         int del_slot = 0;
 565         int extent_type;
 566         int recow;
 567         int ret;
 568
 569         if (drop_cache)
 570                 btrfs_drop_extent_cache(inode, start, end - 1, 0);
 571
 572         path = btrfs_alloc_path();
 573         if (!path)
 574                 return -ENOMEM;
 575
 576         while (1) {
 577                 recow = 0;
 578                 ret = btrfs_lookup_file_extent(trans, root, path, ino,
 579                                                search_start, -1);
 580                 if (ret < 0)
 581                         break;
 582                 if (ret > 0 && path->slots[0] > 0 && search_start == start) {
 583                         leaf = path->nodes[0];
 584                         btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 585                         if (key.objectid == ino &&
 586                             key.type == BTRFS_EXTENT_DATA_KEY)
 587                                 path->slots[0]--;
 588                 }
 589                 ret = 0;
 590 next_slot:
 591                 leaf = path->nodes[0];
 592                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 593                         BUG_ON(del_nr > 0);
 594                         ret = btrfs_next_leaf(root, path);
 595                         if (ret < 0)
 596                                 break;
 597                         if (ret > 0) {
 598                                 ret = 0;
 599                                 break;
 600                         }
 601                         leaf = path->nodes[0];
 602                         recow = 1;
 603                 }
 604
 605                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 606                 if (key.objectid > ino ||
 607                     key.type > BTRFS_EXTENT_DATA_KEY || key.offset >= end)
 608                         break;
 609
 610                 fi = btrfs_item_ptr(leaf, path->slots[0],
 611                                     struct btrfs_file_extent_item);
 612                 extent_type = btrfs_file_extent_type(leaf, fi);
 613
 614                 if (extent_type == BTRFS_FILE_EXTENT_REG ||
 615                     extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
 616                         disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 617                         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
 618                         extent_offset = btrfs_file_extent_offset(leaf, fi);
 619                         extent_end = key.offset +
 620                                 btrfs_file_extent_num_bytes(leaf, fi);
 621                 } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 622                         extent_end = key.offset +
 623                                 btrfs_file_extent_inline_len(leaf, fi);
 624                 } else {
 625                         WARN_ON(1);
 626                         extent_end = search_start;
 627                 }
 628
 629                 if (extent_end <= search_start) {
 630                         path->slots[0]++;
 631                         goto next_slot;
 632                 }
 633
 634                 search_start = max(key.offset, start);
 635                 if (recow) {
 636                         btrfs_release_path(path);
 637                         continue;
 638                 }
 639
 640                 /*
 641                  *     | - range to drop - |
 642                  *  | -------- extent -------- |
 643                  */
 644                 if (start > key.offset && end < extent_end) {
 645                         BUG_ON(del_nr > 0);
 646                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 647
 648                         memcpy(&new_key, &key, sizeof(new_key));
 649                         new_key.offset = start;
 650                         ret = btrfs_duplicate_item(trans, root, path,
 651                                                    &new_key);
 652                         if (ret == -EAGAIN) {
 653                                 btrfs_release_path(path);
 654                                 continue;
 655                         }
 656                         if (ret < 0)
 657                                 break;
 658
 659                         leaf = path->nodes[0];
 660                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
 661                                             struct btrfs_file_extent_item);
 662                         btrfs_set_file_extent_num_bytes(leaf, fi,
 663                                                         start - key.offset);
 664
 665                         fi = btrfs_item_ptr(leaf, path->slots[0],
 666                                             struct btrfs_file_extent_item);
 667
 668                         extent_offset += start - key.offset;
 669                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
 670                         btrfs_set_file_extent_num_bytes(leaf, fi,
 671                                                         extent_end - start);
 672                         btrfs_mark_buffer_dirty(leaf);
 673
 674                         if (disk_bytenr > 0) {
 675                                 ret = btrfs_inc_extent_ref(trans, root,
 676                                                 disk_bytenr, num_bytes, 0,
 677                                                 root->root_key.objectid,
 678                                                 new_key.objectid,
 679                                                 start - extent_offset);
 680                                 BUG_ON(ret);
 681                                 *hint_byte = disk_bytenr;
 682                         }
 683                         key.offset = start;
 684                 }
 685                 /*
 686                  *  | ---- range to drop ----- |
 687                  *      | -------- extent -------- |
 688                  */
 689                 if (start <= key.offset && end < extent_end) {
 690                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 691
 692                         memcpy(&new_key, &key, sizeof(new_key));
 693                         new_key.offset = end;
 694                         btrfs_set_item_key_safe(trans, root, path, &new_key);
 695
 696                         extent_offset += end - key.offset;
 697                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
 698                         btrfs_set_file_extent_num_bytes(leaf, fi,
 699                                                         extent_end - end);
 700                         btrfs_mark_buffer_dirty(leaf);
 701                         if (disk_bytenr > 0) {
 702                                 inode_sub_bytes(inode, end - key.offset);
 703                                 *hint_byte = disk_bytenr;
 704                         }
 705                         break;
 706                 }
 707
 708                 search_start = extent_end;
 709                 /*
 710                  *       | ---- range to drop ----- |
 711                  *  | -------- extent -------- |
 712                  */
 713                 if (start > key.offset && end >= extent_end) {
 714                         BUG_ON(del_nr > 0);
 715                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 716
 717                         btrfs_set_file_extent_num_bytes(leaf, fi,
 718                                                         start - key.offset);
 719                         btrfs_mark_buffer_dirty(leaf);
 720                         if (disk_bytenr > 0) {
 721                                 inode_sub_bytes(inode, extent_end - start);
 722                                 *hint_byte = disk_bytenr;
 723                         }
 724                         if (end == extent_end)
 725                                 break;
 726
 727                         path->slots[0]++;
 728                         goto next_slot;
 729                 }
 730
 731                 /*
 732                  *  | ---- range to drop ----- |
 733                  *    | ------ extent ------ |
 734                  */
 735                 if (start <= key.offset && end >= extent_end) {
 736                         if (del_nr == 0) {
 737                                 del_slot = path->slots[0];
 738                                 del_nr = 1;
 739                         } else {
 740                                 BUG_ON(del_slot + del_nr != path->slots[0]);
 741                                 del_nr++;
 742                         }
 743
 744                         if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 745                                 inode_sub_bytes(inode,
 746                                                 extent_end - key.offset);
 747                                 extent_end = ALIGN(extent_end,
 748                                                    root->sectorsize);
 749                         } else if (disk_bytenr > 0) {
 750                                 ret = btrfs_free_extent(trans, root,
 751                                                 disk_bytenr, num_bytes, 0,
 752                                                 root->root_key.objectid,
 753                                                 key.objectid, key.offset -
 754                                                 extent_offset);
 755                                 BUG_ON(ret);
 756                                 inode_sub_bytes(inode,
 757                                                 extent_end - key.offset);
 758                                 *hint_byte = disk_bytenr;
 759                         }
 760
 761                         if (end == extent_end)
 762                                 break;
 763
 764                         if (path->slots[0] + 1 < btrfs_header_nritems(leaf)) {
 765                                 path->slots[0]++;
 766                                 goto next_slot;
 767                         }
 768
 769                         ret = btrfs_del_items(trans, root, path, del_slot,
 770                                               del_nr);
 771                         BUG_ON(ret);
 772
 773                         del_nr = 0;
 774                         del_slot = 0;
 775
 776                         btrfs_release_path(path);
 777                         continue;
 778                 }
 779
 780                 BUG_ON(1);
 781         }
 782
 783         if (del_nr > 0) {
 784                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
 785                 BUG_ON(ret);
 786         }
 787
 788         btrfs_free_path(path);
 789         return ret;
 790 }
 791
 792 static int extent_mergeable(struct extent_buffer *leaf, int slot,
 793                             u64 objectid, u64 bytenr, u64 orig_offset,
 794                             u64 *start, u64 *end)
 795 {
 796         struct btrfs_file_extent_item *fi;
 797         struct btrfs_key key;
 798         u64 extent_end;
 799
 800         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
 801                 return 0;
 802
 803         btrfs_item_key_to_cpu(leaf, &key, slot);
 804         if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
 805                 return 0;
 806
 807         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
 808         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
 809             btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
 810             btrfs_file_extent_offset(leaf, fi) != key.offset - orig_offset ||
 811             btrfs_file_extent_compression(leaf, fi) ||
 812             btrfs_file_extent_encryption(leaf, fi) ||
 813             btrfs_file_extent_other_encoding(leaf, fi))
 814                 return 0;
 815
 816         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 817         if ((*start && *start != key.offset) || (*end && *end != extent_end))
 818                 return 0;
 819
 820         *start = key.offset;
 821         *end = extent_end;
 822         return 1;
 823 }
 824
 825 /*
 826  * Mark extent in the range start - end as written.
 827  *
 828  * This changes extent type from 'pre-allocated' to 'regular'. If only
 829  * part of extent is marked as written, the extent will be split into
 830  * two or three.
 831  */
 832 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
 833                               struct inode *inode, u64 start, u64 end)
 834 {
 835         struct btrfs_root *root = BTRFS_I(inode)->root;
 836         struct extent_buffer *leaf;
 837         struct btrfs_path *path;
 838         struct btrfs_file_extent_item *fi;
 839         struct btrfs_key key;
 840         struct btrfs_key new_key;
 841         u64 bytenr;
 842         u64 num_bytes;
 843         u64 extent_end;
 844         u64 orig_offset;
 845         u64 other_start;
 846         u64 other_end;
 847         u64 split;
 848         int del_nr = 0;
 849         int del_slot = 0;
 850         int recow;
 851         int ret;
 852         u64 ino = btrfs_ino(inode);
 853
 854         btrfs_drop_extent_cache(inode, start, end - 1, 0);
 855
 856         path = btrfs_alloc_path();
 857         if (!path)
 858                 return -ENOMEM;
 859 again:
 860         recow = 0;
 861         split = start;
 862         key.objectid = ino;
 863         key.type = BTRFS_EXTENT_DATA_KEY;
 864         key.offset = split;
 865
 866         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 867         if (ret < 0)
 868                 goto out;
 869         if (ret > 0 && path->slots[0] > 0)
 870                 path->slots[0]--;
 871
 872         leaf = path->nodes[0];
 873         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 874         BUG_ON(key.objectid != ino || key.type != BTRFS_EXTENT_DATA_KEY);
 875         fi = btrfs_item_ptr(leaf, path->slots[0],
 876                             struct btrfs_file_extent_item);
 877         BUG_ON(btrfs_file_extent_type(leaf, fi) !=
 878                BTRFS_FILE_EXTENT_PREALLOC);
 879         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 880         BUG_ON(key.offset > start || extent_end < end);
 881
 882         bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 883         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
 884         orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
 885         memcpy(&new_key, &key, sizeof(new_key));
 886
 887         if (start == key.offset && end < extent_end) {
 888                 other_start = 0;
 889                 other_end = start;
 890                 if (extent_mergeable(leaf, path->slots[0] - 1,
 891                                      ino, bytenr, orig_offset,
 892                                      &other_start, &other_end)) {
 893                         new_key.offset = end;
 894                         btrfs_set_item_key_safe(trans, root, path, &new_key);
 895                         fi = btrfs_item_ptr(leaf, path->slots[0],
 896                                             struct btrfs_file_extent_item);
 897                         btrfs_set_file_extent_num_bytes(leaf, fi,
 898                                                         extent_end - end);
 899                         btrfs_set_file_extent_offset(leaf, fi,
 900                                                      end - orig_offset);
 901                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
 902                                             struct btrfs_file_extent_item);
 903                         btrfs_set_file_extent_num_bytes(leaf, fi,
 904                                                         end - other_start);
 905                         btrfs_mark_buffer_dirty(leaf);
 906                         goto out;
 907                 }
 908         }
 909
 910         if (start > key.offset && end == extent_end) {
 911                 other_start = end;
 912                 other_end = 0;
 913                 if (extent_mergeable(leaf, path->slots[0] + 1,
 914                                      ino, bytenr, orig_offset,
 915                                      &other_start, &other_end)) {
 916                         fi = btrfs_item_ptr(leaf, path->slots[0],
 917                                             struct btrfs_file_extent_item);
 918                         btrfs_set_file_extent_num_bytes(leaf, fi,
 919                                                         start - key.offset);
 920                         path->slots[0]++;
 921                         new_key.offset = start;
 922                         btrfs_set_item_key_safe(trans, root, path, &new_key);
 923
 924                         fi = btrfs_item_ptr(leaf, path->slots[0],
 925                                             struct btrfs_file_extent_item);
 926                         btrfs_set_file_extent_num_bytes(leaf, fi,
 927                                                         other_end - start);
 928                         btrfs_set_file_extent_offset(leaf, fi,
 929                                                      start - orig_offset);
 930                         btrfs_mark_buffer_dirty(leaf);
 931                         goto out;
 932                 }
 933         }
 934
 935         while (start > key.offset || end < extent_end) {
 936                 if (key.offset == start)
 937                         split = end;
 938
 939                 new_key.offset = split;
 940                 ret = btrfs_duplicate_item(trans, root, path, &new_key);
 941                 if (ret == -EAGAIN) {
 942                         btrfs_release_path(path);
 943                         goto again;
 944                 }
 945                 BUG_ON(ret < 0);
 946
 947                 leaf = path->nodes[0];
 948                 fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
 949                                     struct btrfs_file_extent_item);
 950                 btrfs_set_file_extent_num_bytes(leaf, fi,
 951                                                 split - key.offset);
 952
 953                 fi = btrfs_item_ptr(leaf, path->slots[0],
 954                                     struct btrfs_file_extent_item);
 955
 956                 btrfs_set_file_extent_offset(leaf, fi, split - orig_offset);
 957                 btrfs_set_file_extent_num_bytes(leaf, fi,
 958                                                 extent_end - split);
 959                 btrfs_mark_buffer_dirty(leaf);
 960
 961                 ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
 962                                            root->root_key.objectid,
 963                                            ino, orig_offset);
 964                 BUG_ON(ret);
 965
 966                 if (split == start) {
 967                         key.offset = start;
 968                 } else {
 969                         BUG_ON(start != key.offset);
 970                         path->slots[0]--;
 971                         extent_end = end;
 972                 }
 973                 recow = 1;
 974         }
 975
 976         other_start = end;
 977         other_end = 0;
 978         if (extent_mergeable(leaf, path->slots[0] + 1,
 979                              ino, bytenr, orig_offset,
 980                              &other_start, &other_end)) {
 981                 if (recow) {
 982                         btrfs_release_path(path);
 983                         goto again;
 984                 }
 985                 extent_end = other_end;
 986                 del_slot = path->slots[0] + 1;
 987                 del_nr++;
 988                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
 989                                         0, root->root_key.objectid,
 990                                         ino, orig_offset);
 991                 BUG_ON(ret);
 992         }
 993         other_start = 0;
 994         other_end = start;
 995         if (extent_mergeable(leaf, path->slots[0] - 1,
 996                              ino, bytenr, orig_offset,
 997                              &other_start, &other_end)) {
 998                 if (recow) {
 999                         btrfs_release_path(path);
1000                         goto again;
1001                 }
1002                 key.offset = other_start;
1003                 del_slot = path->slots[0];
1004                 del_nr++;
1005                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1006                                         0, root->root_key.objectid,
1007                                         ino, orig_offset);
1008                 BUG_ON(ret);
1009         }
1010         if (del_nr == 0) {
1011                 fi = btrfs_item_ptr(leaf, path->slots[0],
1012                            struct btrfs_file_extent_item);
1013                 btrfs_set_file_extent_type(leaf, fi,
1014                                            BTRFS_FILE_EXTENT_REG);
1015                 btrfs_mark_buffer_dirty(leaf);
1016         } else {
1017                 fi = btrfs_item_ptr(leaf, del_slot - 1,
1018                            struct btrfs_file_extent_item);
1019                 btrfs_set_file_extent_type(leaf, fi,
1020                                            BTRFS_FILE_EXTENT_REG);
1021                 btrfs_set_file_extent_num_bytes(leaf, fi,
1022                                                 extent_end - key.offset);
1023                 btrfs_mark_buffer_dirty(leaf);
1024
1025                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
1026                 BUG_ON(ret);
1027         }
1028 out:
1029         btrfs_free_path(path);
1030         return 0;
1031 }
1032
1033 /*
1034  * on error we return an unlocked page and the error value
1035  * on success we return a locked page and 0
1036  */
1037 static int prepare_uptodate_page(struct page *page, u64 pos)
1038 {
1039         int ret = 0;
1040
1041         if ((pos & (PAGE_CACHE_SIZE - 1)) && !PageUptodate(page)) {
1042                 ret = btrfs_readpage(NULL, page);
1043                 if (ret)
1044                         return ret;
1045                 lock_page(page);
1046                 if (!PageUptodate(page)) {
1047                         unlock_page(page);
1048                         return -EIO;
1049                 }
1050         }
1051         return 0;
1052 }
1053
1054 /*
1055  * this gets pages into the page cache and locks them down, it also properly
1056  * waits for data=ordered extents to finish before allowing the pages to be
1057  * modified.
1058  */
1059 static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
1060                          struct page **pages, size_t num_pages,
1061                          loff_t pos, unsigned long first_index,
1062                          unsigned long last_index, size_t write_bytes)
1063 {
1064         struct extent_state *cached_state = NULL;
1065         int i;
1066         unsigned long index = pos >> PAGE_CACHE_SHIFT;
1067         struct inode *inode = fdentry(file)->d_inode;
1068         int err = 0;
1069         int faili = 0;
1070         u64 start_pos;
1071         u64 last_pos;
1072
1073         start_pos = pos & ~((u64)root->sectorsize - 1);
1074         last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
1075
1076         if (start_pos > inode->i_size) {
1077                 err = btrfs_cont_expand(inode, i_size_read(inode), start_pos);
1078                 if (err)
1079                         return err;
1080         }
1081
1082 again:
1083         for (i = 0; i < num_pages; i++) {
1084                 pages[i] = find_or_create_page(inode->i_mapping, index + i,
1085                                                GFP_NOFS);
1086                 if (!pages[i]) {
1087                         faili = i - 1;
1088                         err = -ENOMEM;
1089                         goto fail;
1090                 }
1091
1092                 if (i == 0)
1093                         err = prepare_uptodate_page(pages[i], pos);
1094                 if (i == num_pages - 1)
1095                         err = prepare_uptodate_page(pages[i],
1096                                                     pos + write_bytes);
1097                 if (err) {
1098                         page_cache_release(pages[i]);
1099                         faili = i - 1;
1100                         goto fail;
1101                 }
1102                 wait_on_page_writeback(pages[i]);
1103         }
1104         err = 0;
1105         if (start_pos < inode->i_size) {
1106                 struct btrfs_ordered_extent *ordered;
1107                 lock_extent_bits(&BTRFS_I(inode)->io_tree,
1108                                  start_pos, last_pos - 1, 0, &cached_state,
1109                                  GFP_NOFS);
1110                 ordered = btrfs_lookup_first_ordered_extent(inode,
1111                                                             last_pos - 1);
1112                 if (ordered &&
1113                     ordered->file_offset + ordered->len > start_pos &&
1114                     ordered->file_offset < last_pos) {
1115                         btrfs_put_ordered_extent(ordered);
1116                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1117                                              start_pos, last_pos - 1,
1118                                              &cached_state, GFP_NOFS);
1119                         for (i = 0; i < num_pages; i++) {
1120                                 unlock_page(pages[i]);
1121                                 page_cache_release(pages[i]);
1122                         }
1123                         btrfs_wait_ordered_range(inode, start_pos,
1124                                                  last_pos - start_pos);
1125                         goto again;
1126                 }
1127                 if (ordered)
1128                         btrfs_put_ordered_extent(ordered);
1129
1130                 clear_extent_bit(&BTRFS_I(inode)->io_tree, start_pos,
1131                                   last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC |
1132                                   EXTENT_DO_ACCOUNTING, 0, 0, &cached_state,
1133                                   GFP_NOFS);
1134                 unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1135                                      start_pos, last_pos - 1, &cached_state,
1136                                      GFP_NOFS);
1137         }
1138         for (i = 0; i < num_pages; i++) {
1139                 clear_page_dirty_for_io(pages[i]);
1140                 set_page_extent_mapped(pages[i]);
1141                 WARN_ON(!PageLocked(pages[i]));
1142         }
1143         return 0;
1144 fail:
1145         while (faili >= 0) {
1146                 unlock_page(pages[faili]);
1147                 page_cache_release(pages[faili]);
1148                 faili--;
1149         }
1150         return err;
1151
1152 }
1153
1154 static noinline ssize_t __btrfs_buffered_write(struct file *file,
1155                                                struct iov_iter *i,
1156                                                loff_t pos)
1157 {
1158         struct inode *inode = fdentry(file)->d_inode;
1159         struct btrfs_root *root = BTRFS_I(inode)->root;
1160         struct page **pages = NULL;
1161         unsigned long first_index;
1162         unsigned long last_index;
1163         size_t num_written = 0;
1164         int nrptrs;
1165         int ret = 0;
1166
1167         nrptrs = min((iov_iter_count(i) + PAGE_CACHE_SIZE - 1) /
1168                      PAGE_CACHE_SIZE, PAGE_CACHE_SIZE /
1169                      (sizeof(struct page *)));
1170         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
1171         if (!pages)
1172                 return -ENOMEM;
1173
1174         first_index = pos >> PAGE_CACHE_SHIFT;
1175         last_index = (pos + iov_iter_count(i)) >> PAGE_CACHE_SHIFT;
1176
1177         while (iov_iter_count(i) > 0) {
1178                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
1179                 size_t write_bytes = min(iov_iter_count(i),
1180                                          nrptrs * (size_t)PAGE_CACHE_SIZE -
1181                                          offset);
1182                 size_t num_pages = (write_bytes + offset +
1183                                     PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1184                 size_t dirty_pages;
1185                 size_t copied;
1186
1187                 WARN_ON(num_pages > nrptrs);
1188
1189                 /*
1190                  * Fault pages before locking them in prepare_pages
1191                  * to avoid recursive lock
1192                  */
1193                 if (unlikely(iov_iter_fault_in_readable(i, write_bytes))) {
1194                         ret = -EFAULT;
1195                         break;
1196                 }
1197
1198                 ret = btrfs_delalloc_reserve_space(inode,
1199                                         num_pages << PAGE_CACHE_SHIFT);
1200                 if (ret)
1201                         break;
1202
1203                 /*
1204                  * This is going to setup the pages array with the number of
1205                  * pages we want, so we don't really need to worry about the
1206                  * contents of pages from loop to loop
1207                  */
1208                 ret = prepare_pages(root, file, pages, num_pages,
1209                                     pos, first_index, last_index,
1210                                     write_bytes);
1211                 if (ret) {
1212                         btrfs_delalloc_release_space(inode,
1213                                         num_pages << PAGE_CACHE_SHIFT);
1214                         break;
1215                 }
1216
1217                 copied = btrfs_copy_from_user(pos, num_pages,
1218                                            write_bytes, pages, i);
1219
1220                 /*
1221                  * if we have trouble faulting in the pages, fall
1222                  * back to one page at a time
1223                  */
1224                 if (copied < write_bytes)
1225                         nrptrs = 1;
1226
1227                 if (copied == 0)
1228                         dirty_pages = 0;
1229                 else
1230                         dirty_pages = (copied + offset +
1231                                        PAGE_CACHE_SIZE - 1) >>
1232                                        PAGE_CACHE_SHIFT;
1233
1234                 /*
1235                  * If we had a short copy we need to release the excess delaloc
1236                  * bytes we reserved.  We need to increment outstanding_extents
1237                  * because btrfs_delalloc_release_space will decrement it, but
1238                  * we still have an outstanding extent for the chunk we actually
1239                  * managed to copy.
1240                  */
1241                 if (num_pages > dirty_pages) {
1242                         if (copied > 0) {
1243                                 spin_lock(&BTRFS_I(inode)->lock);
1244                                 BTRFS_I(inode)->outstanding_extents++;
1245                                 spin_unlock(&BTRFS_I(inode)->lock);
1246                         }
1247                         btrfs_delalloc_release_space(inode,
1248                                         (num_pages - dirty_pages) <<
1249                                         PAGE_CACHE_SHIFT);
1250                 }
1251
1252                 if (copied > 0) {
1253                         ret = btrfs_dirty_pages(root, inode, pages,
1254                                                 dirty_pages, pos, copied,
1255                                                 NULL);
1256                         if (ret) {
1257                                 btrfs_delalloc_release_space(inode,
1258                                         dirty_pages << PAGE_CACHE_SHIFT);
1259                                 btrfs_drop_pages(pages, num_pages);
1260                                 break;
1261                         }
1262                 }
1263
1264                 btrfs_drop_pages(pages, num_pages);
1265
1266                 cond_resched();
1267
1268                 balance_dirty_pages_ratelimited_nr(inode->i_mapping,
1269                                                    dirty_pages);
1270                 if (dirty_pages < (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
1271                         btrfs_btree_balance_dirty(root, 1);
1272                 btrfs_throttle(root);
1273
1274                 pos += copied;
1275                 num_written += copied;
1276         }
1277
1278         kfree(pages);
1279
1280         return num_written ? num_written : ret;
1281 }
1282
1283 static ssize_t __btrfs_direct_write(struct kiocb *iocb,
1284                                     const struct iovec *iov,
1285                                     unsigned long nr_segs, loff_t pos,
1286                                     loff_t *ppos, size_t count, size_t ocount)
1287 {
1288         struct file *file = iocb->ki_filp;
1289         struct inode *inode = fdentry(file)->d_inode;
1290         struct iov_iter i;
1291         ssize_t written;
1292         ssize_t written_buffered;
1293         loff_t endbyte;
1294         int err;
1295
1296         written = generic_file_direct_write(iocb, iov, &nr_segs, pos, ppos,
1297                                             count, ocount);
1298
1299         /*
1300          * the generic O_DIRECT will update in-memory i_size after the
1301          * DIOs are done.  But our endio handlers that update the on
1302          * disk i_size never update past the in memory i_size.  So we
1303          * need one more update here to catch any additions to the
1304          * file
1305          */
1306         if (inode->i_size != BTRFS_I(inode)->disk_i_size) {
1307                 btrfs_ordered_update_i_size(inode, inode->i_size, NULL);
1308                 mark_inode_dirty(inode);
1309         }
1310
1311         if (written < 0 || written == count)
1312                 return written;
1313
1314         pos += written;
1315         count -= written;
1316         iov_iter_init(&i, iov, nr_segs, count, written);
1317         written_buffered = __btrfs_buffered_write(file, &i, pos);
1318         if (written_buffered < 0) {
1319                 err = written_buffered;
1320                 goto out;
1321         }
1322         endbyte = pos + written_buffered - 1;
1323         err = filemap_write_and_wait_range(file->f_mapping, pos, endbyte);
1324         if (err)
1325                 goto out;
1326         written += written_buffered;
1327         *ppos = pos + written_buffered;
1328         invalidate_mapping_pages(file->f_mapping, pos >> PAGE_CACHE_SHIFT,
1329                                  endbyte >> PAGE_CACHE_SHIFT);
1330 out:
1331         return written ? written : err;
1332 }
1333
1334 static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
1335                                     const struct iovec *iov,
1336                                     unsigned long nr_segs, loff_t pos)
1337 {
1338         struct file *file = iocb->ki_filp;
1339         struct inode *inode = fdentry(file)->d_inode;
1340         struct btrfs_root *root = BTRFS_I(inode)->root;
1341         loff_t *ppos = &iocb->ki_pos;
1342         ssize_t num_written = 0;
1343         ssize_t err = 0;
1344         size_t count, ocount;
1345
1346         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
1347
1348         mutex_lock(&inode->i_mutex);
1349
1350         err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
1351         if (err) {
1352                 mutex_unlock(&inode->i_mutex);
1353                 goto out;
1354         }
1355         count = ocount;
1356
1357         current->backing_dev_info = inode->i_mapping->backing_dev_info;
1358         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
1359         if (err) {
1360                 mutex_unlock(&inode->i_mutex);
1361                 goto out;
1362         }
1363
1364         if (count == 0) {
1365                 mutex_unlock(&inode->i_mutex);
1366                 goto out;
1367         }
1368
1369         err = file_remove_suid(file);
1370         if (err) {
1371                 mutex_unlock(&inode->i_mutex);
1372                 goto out;
1373         }
1374
1375         /*
1376          * If BTRFS flips readonly due to some impossible error
1377          * (fs_info->fs_state now has BTRFS_SUPER_FLAG_ERROR),
1378          * although we have opened a file as writable, we have
1379          * to stop this write operation to ensure FS consistency.
1380          */
1381         if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
1382                 mutex_unlock(&inode->i_mutex);
1383                 err = -EROFS;
1384                 goto out;
1385         }
1386
1387         file_update_time(file);
1388         BTRFS_I(inode)->sequence++;
1389
1390         if (unlikely(file->f_flags & O_DIRECT)) {
1391                 num_written = __btrfs_direct_write(iocb, iov, nr_segs,
1392                                                    pos, ppos, count, ocount);
1393         } else {
1394                 struct iov_iter i;
1395
1396                 iov_iter_init(&i, iov, nr_segs, count, num_written);
1397
1398                 num_written = __btrfs_buffered_write(file, &i, pos);
1399                 if (num_written > 0)
1400                         *ppos = pos + num_written;
1401         }
1402
1403         mutex_unlock(&inode->i_mutex);
1404
1405         /*
1406          * we want to make sure fsync finds this change
1407          * but we haven't joined a transaction running right now.
1408          *
1409          * Later on, someone is sure to update the inode and get the
1410          * real transid recorded.
1411          *
1412          * We set last_trans now to the fs_info generation + 1,
1413          * this will either be one more than the running transaction
1414          * or the generation used for the next transaction if there isn't
1415          * one running right now.
1416          */
1417         BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
1418         if (num_written > 0 || num_written == -EIOCBQUEUED) {
1419                 err = generic_write_sync(file, pos, num_written);
1420                 if (err < 0 && num_written > 0)
1421                         num_written = err;
1422         }
1423 out:
1424         current->backing_dev_info = NULL;
1425         return num_written ? num_written : err;
1426 }
1427
1428 int btrfs_release_file(struct inode *inode, struct file *filp)
1429 {
1430         /*
1431          * ordered_data_close is set by settattr when we are about to truncate
1432          * a file from a non-zero size to a zero size.  This tries to
1433          * flush down new bytes that may have been written if the
1434          * application were using truncate to replace a file in place.
1435          */
1436         if (BTRFS_I(inode)->ordered_data_close) {
1437                 BTRFS_I(inode)->ordered_data_close = 0;
1438                 btrfs_add_ordered_operation(NULL, BTRFS_I(inode)->root, inode);
1439                 if (inode->i_size > BTRFS_ORDERED_OPERATIONS_FLUSH_LIMIT)
1440                         filemap_flush(inode->i_mapping);
1441         }
1442         if (filp->private_data)
1443                 btrfs_ioctl_trans_end(filp);
1444         return 0;
1445 }
1446
1447 /*
1448  * fsync call for both files and directories.  This logs the inode into
1449  * the tree log instead of forcing full commits whenever possible.
1450  *
1451  * It needs to call filemap_fdatawait so that all ordered extent updates are
1452  * in the metadata btree are up to date for copying to the log.
1453  *
1454  * It drops the inode mutex before doing the tree log commit.  This is an
1455  * important optimization for directories because holding the mutex prevents
1456  * new operations on the dir while we write to disk.
1457  */
1458 int btrfs_sync_file(struct file *file, int datasync)
1459 {
1460         struct dentry *dentry = file->f_path.dentry;
1461         struct inode *inode = dentry->d_inode;
1462         struct btrfs_root *root = BTRFS_I(inode)->root;
1463         int ret = 0;
1464         struct btrfs_trans_handle *trans;
1465
1466         trace_btrfs_sync_file(file, datasync);
1467
1468         /* we wait first, since the writeback may change the inode */
1469         root->log_batch++;
1470         /* the VFS called filemap_fdatawrite for us */
1471         btrfs_wait_ordered_range(inode, 0, (u64)-1);
1472         root->log_batch++;
1473
1474         /*
1475          * check the transaction that last modified this inode
1476          * and see if its already been committed
1477          */
1478         if (!BTRFS_I(inode)->last_trans)
1479                 goto out;
1480
1481         /*
1482          * if the last transaction that changed this file was before
1483          * the current transaction, we can bail out now without any
1484          * syncing
1485          */
1486         smp_mb();
1487         if (BTRFS_I(inode)->last_trans <=
1488             root->fs_info->last_trans_committed) {
1489                 BTRFS_I(inode)->last_trans = 0;
1490                 goto out;
1491         }
1492
1493         /*
1494          * ok we haven't committed the transaction yet, lets do a commit
1495          */
1496         if (file->private_data)
1497                 btrfs_ioctl_trans_end(file);
1498
1499         trans = btrfs_start_transaction(root, 0);
1500         if (IS_ERR(trans)) {
1501                 ret = PTR_ERR(trans);
1502                 goto out;
1503         }
1504
1505         ret = btrfs_log_dentry_safe(trans, root, dentry);
1506         if (ret < 0)
1507                 goto out;
1508
1509         /* we've logged all the items and now have a consistent
1510          * version of the file in the log.  It is possible that
1511          * someone will come in and modify the file, but that's
1512          * fine because the log is consistent on disk, and we
1513          * have references to all of the file's extents
1514          *
1515          * It is possible that someone will come in and log the
1516          * file again, but that will end up using the synchronization
1517          * inside btrfs_sync_log to keep things safe.
1518          */
1519         mutex_unlock(&dentry->d_inode->i_mutex);
1520
1521         if (ret != BTRFS_NO_LOG_SYNC) {
1522                 if (ret > 0) {
1523                         ret = btrfs_commit_transaction(trans, root);
1524                 } else {
1525                         ret = btrfs_sync_log(trans, root);
1526                         if (ret == 0)
1527                                 ret = btrfs_end_transaction(trans, root);
1528                         else
1529                                 ret = btrfs_commit_transaction(trans, root);
1530                 }
1531         } else {
1532                 ret = btrfs_end_transaction(trans, root);
1533         }
1534         mutex_lock(&dentry->d_inode->i_mutex);
1535 out:
1536         return ret > 0 ? -EIO : ret;
1537 }
1538
1539 static const struct vm_operations_struct btrfs_file_vm_ops = {
1540         .fault          = filemap_fault,
1541         .page_mkwrite   = btrfs_page_mkwrite,
1542 };
1543
1544 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
1545 {
1546         struct address_space *mapping = filp->f_mapping;
1547
1548         if (!mapping->a_ops->readpage)
1549                 return -ENOEXEC;
1550
1551         file_accessed(filp);
1552         vma->vm_ops = &btrfs_file_vm_ops;
1553         vma->vm_flags |= VM_CAN_NONLINEAR;
1554
1555         return 0;
1556 }
1557
1558 static long btrfs_fallocate(struct file *file, int mode,
1559                             loff_t offset, loff_t len)
1560 {
1561         struct inode *inode = file->f_path.dentry->d_inode;
1562         struct extent_state *cached_state = NULL;
1563         u64 cur_offset;
1564         u64 last_byte;
1565         u64 alloc_start;
1566         u64 alloc_end;
1567         u64 alloc_hint = 0;
1568         u64 locked_end;
1569         u64 mask = BTRFS_I(inode)->root->sectorsize - 1;
1570         struct extent_map *em;
1571         int ret;
1572
1573         alloc_start = offset & ~mask;
1574         alloc_end =  (offset + len + mask) & ~mask;
1575
1576         /* We only support the FALLOC_FL_KEEP_SIZE mode */
1577         if (mode & ~FALLOC_FL_KEEP_SIZE)
1578                 return -EOPNOTSUPP;
1579
1580         /*
1581          * wait for ordered IO before we have any locks.  We'll loop again
1582          * below with the locks held.
1583          */
1584         btrfs_wait_ordered_range(inode, alloc_start, alloc_end - alloc_start);
1585
1586         mutex_lock(&inode->i_mutex);
1587         ret = inode_newsize_ok(inode, alloc_end);
1588         if (ret)
1589                 goto out;
1590
1591         if (alloc_start > inode->i_size) {
1592                 ret = btrfs_cont_expand(inode, i_size_read(inode),
1593                                         alloc_start);
1594                 if (ret)
1595                         goto out;
1596         }
1597
1598         ret = btrfs_check_data_free_space(inode, alloc_end - alloc_start);
1599         if (ret)
1600                 goto out;
1601
1602         locked_end = alloc_end - 1;
1603         while (1) {
1604                 struct btrfs_ordered_extent *ordered;
1605
1606                 /* the extent lock is ordered inside the running
1607                  * transaction
1608                  */
1609                 lock_extent_bits(&BTRFS_I(inode)->io_tree, alloc_start,
1610                                  locked_end, 0, &cached_state, GFP_NOFS);
1611                 ordered = btrfs_lookup_first_ordered_extent(inode,
1612                                                             alloc_end - 1);
1613                 if (ordered &&
1614                     ordered->file_offset + ordered->len > alloc_start &&
1615                     ordered->file_offset < alloc_end) {
1616                         btrfs_put_ordered_extent(ordered);
1617                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1618                                              alloc_start, locked_end,
1619                                              &cached_state, GFP_NOFS);
1620                         /*
1621                          * we can't wait on the range with the transaction
1622                          * running or with the extent lock held
1623                          */
1624                         btrfs_wait_ordered_range(inode, alloc_start,
1625                                                  alloc_end - alloc_start);
1626                 } else {
1627                         if (ordered)
1628                                 btrfs_put_ordered_extent(ordered);
1629                         break;
1630                 }
1631         }
1632
1633         cur_offset = alloc_start;
1634         while (1) {
1635                 em = btrfs_get_extent(inode, NULL, 0, cur_offset,
1636                                       alloc_end - cur_offset, 0);
1637                 BUG_ON(IS_ERR_OR_NULL(em));
1638                 last_byte = min(extent_map_end(em), alloc_end);
1639                 last_byte = (last_byte + mask) & ~mask;
1640                 if (em->block_start == EXTENT_MAP_HOLE ||
1641                     (cur_offset >= inode->i_size &&
1642                      !test_bit(EXTENT_FLAG_PREALLOC, &em->flags))) {
1643                         ret = btrfs_prealloc_file_range(inode, mode, cur_offset,
1644                                                         last_byte - cur_offset,
1645                                                         1 << inode->i_blkbits,
1646                                                         offset + len,
1647                                                         &alloc_hint);
1648                         if (ret < 0) {
1649                                 free_extent_map(em);
1650                                 break;
1651                         }
1652                 }
1653                 free_extent_map(em);
1654
1655                 cur_offset = last_byte;
1656                 if (cur_offset >= alloc_end) {
1657                         ret = 0;
1658                         break;
1659                 }
1660         }
1661         unlock_extent_cached(&BTRFS_I(inode)->io_tree, alloc_start, locked_end,
1662                              &cached_state, GFP_NOFS);
1663
1664         btrfs_free_reserved_data_space(inode, alloc_end - alloc_start);
1665 out:
1666         mutex_unlock(&inode->i_mutex);
1667         return ret;
1668 }
1669
1670 const struct file_operations btrfs_file_operations = {
1671         .llseek         = generic_file_llseek,
1672         .read           = do_sync_read,
1673         .write          = do_sync_write,
1674         .aio_read       = generic_file_aio_read,
1675         .splice_read    = generic_file_splice_read,
1676         .aio_write      = btrfs_file_aio_write,
1677         .mmap           = btrfs_file_mmap,
1678         .open           = generic_file_open,
1679         .release        = btrfs_release_file,
1680         .fsync          = btrfs_sync_file,
1681         .fallocate      = btrfs_fallocate,
1682         .unlocked_ioctl = btrfs_ioctl,
1683 #ifdef CONFIG_COMPAT
1684         .compat_ioctl   = btrfs_ioctl,
1685 #endif
1686 };