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