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                                          int write_bytes,
  49                                          struct page **prepared_pages,
  50                                          struct iov_iter *i)
  51 {
  52         size_t copied = 0;
  53         int pg = 0;
  54         int offset = pos & (PAGE_CACHE_SIZE - 1);
  55         int total_copied = 0;
  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                 iov_iter_advance(i, copied);
  74                 write_bytes -= copied;
  75                 total_copied += copied;
  76
  77                 /* Return to btrfs_file_aio_write to fault page */
  78                 if (unlikely(copied == 0)) {
  79                         break;
  80                 }
  81
  82                 if (unlikely(copied < PAGE_CACHE_SIZE - offset)) {
  83                         offset += copied;
  84                 } else {
  85                         pg++;
  86                         offset = 0;
  87                 }
  88         }
  89         return total_copied;
  90 }
  91
  92 /*
  93  * unlocks pages after btrfs_file_write is done with them
  94  */
  95 static noinline void btrfs_drop_pages(struct page **pages, size_t num_pages)
  96 {
  97         size_t i;
  98         for (i = 0; i < num_pages; i++) {
  99                 if (!pages[i])
 100                         break;
 101                 /* page checked is some magic around finding pages that
 102                  * have been modified without going through btrfs_set_page_dirty
 103                  * clear it here
 104                  */
 105                 ClearPageChecked(pages[i]);
 106                 unlock_page(pages[i]);
 107                 mark_page_accessed(pages[i]);
 108                 page_cache_release(pages[i]);
 109         }
 110 }
 111
 112 /*
 113  * after copy_from_user, pages need to be dirtied and we need to make
 114  * sure holes are created between the current EOF and the start of
 115  * any next extents (if required).
 116  *
 117  * this also makes the decision about creating an inline extent vs
 118  * doing real data extents, marking pages dirty and delalloc as required.
 119  */
 120 static noinline int dirty_and_release_pages(struct btrfs_trans_handle *trans,
 121                                    struct btrfs_root *root,
 122                                    struct file *file,
 123                                    struct page **pages,
 124                                    size_t num_pages,
 125                                    loff_t pos,
 126                                    size_t write_bytes)
 127 {
 128         int err = 0;
 129         int i;
 130         struct inode *inode = fdentry(file)->d_inode;
 131         u64 num_bytes;
 132         u64 start_pos;
 133         u64 end_of_last_block;
 134         u64 end_pos = pos + write_bytes;
 135         loff_t isize = i_size_read(inode);
 136
 137         start_pos = pos & ~((u64)root->sectorsize - 1);
 138         num_bytes = (write_bytes + pos - start_pos +
 139                     root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
 140
 141         end_of_last_block = start_pos + num_bytes - 1;
 142         err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block,
 143                                         NULL);
 144         BUG_ON(err);
 145
 146         for (i = 0; i < num_pages; i++) {
 147                 struct page *p = pages[i];
 148                 SetPageUptodate(p);
 149                 ClearPageChecked(p);
 150                 set_page_dirty(p);
 151         }
 152         if (end_pos > isize) {
 153                 i_size_write(inode, end_pos);
 154                 /* we've only changed i_size in ram, and we haven't updated
 155                  * the disk i_size.  There is no need to log the inode
 156                  * at this time.
 157                  */
 158         }
 159         return 0;
 160 }
 161
 162 /*
 163  * this drops all the extents in the cache that intersect the range
 164  * [start, end].  Existing extents are split as required.
 165  */
 166 int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
 167                             int skip_pinned)
 168 {
 169         struct extent_map *em;
 170         struct extent_map *split = NULL;
 171         struct extent_map *split2 = NULL;
 172         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
 173         u64 len = end - start + 1;
 174         int ret;
 175         int testend = 1;
 176         unsigned long flags;
 177         int compressed = 0;
 178
 179         WARN_ON(end < start);
 180         if (end == (u64)-1) {
 181                 len = (u64)-1;
 182                 testend = 0;
 183         }
 184         while (1) {
 185                 if (!split)
 186                         split = alloc_extent_map(GFP_NOFS);
 187                 if (!split2)
 188                         split2 = alloc_extent_map(GFP_NOFS);
 189
 190                 write_lock(&em_tree->lock);
 191                 em = lookup_extent_mapping(em_tree, start, len);
 192                 if (!em) {
 193                         write_unlock(&em_tree->lock);
 194                         break;
 195                 }
 196                 flags = em->flags;
 197                 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
 198                         if (testend && em->start + em->len >= start + len) {
 199                                 free_extent_map(em);
 200                                 write_unlock(&em_tree->lock);
 201                                 break;
 202                         }
 203                         start = em->start + em->len;
 204                         if (testend)
 205                                 len = start + len - (em->start + em->len);
 206                         free_extent_map(em);
 207                         write_unlock(&em_tree->lock);
 208                         continue;
 209                 }
 210                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 211                 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
 212                 remove_extent_mapping(em_tree, em);
 213
 214                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 215                     em->start < start) {
 216                         split->start = em->start;
 217                         split->len = start - em->start;
 218                         split->orig_start = em->orig_start;
 219                         split->block_start = em->block_start;
 220
 221                         if (compressed)
 222                                 split->block_len = em->block_len;
 223                         else
 224                                 split->block_len = split->len;
 225
 226                         split->bdev = em->bdev;
 227                         split->flags = flags;
 228                         split->compress_type = em->compress_type;
 229                         ret = add_extent_mapping(em_tree, split);
 230                         BUG_ON(ret);
 231                         free_extent_map(split);
 232                         split = split2;
 233                         split2 = NULL;
 234                 }
 235                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 236                     testend && em->start + em->len > start + len) {
 237                         u64 diff = start + len - em->start;
 238
 239                         split->start = start + len;
 240                         split->len = em->start + em->len - (start + len);
 241                         split->bdev = em->bdev;
 242                         split->flags = flags;
 243                         split->compress_type = em->compress_type;
 244
 245                         if (compressed) {
 246                                 split->block_len = em->block_len;
 247                                 split->block_start = em->block_start;
 248                                 split->orig_start = em->orig_start;
 249                         } else {
 250                                 split->block_len = split->len;
 251                                 split->block_start = em->block_start + diff;
 252                                 split->orig_start = split->start;
 253                         }
 254
 255                         ret = add_extent_mapping(em_tree, split);
 256                         BUG_ON(ret);
 257                         free_extent_map(split);
 258                         split = NULL;
 259                 }
 260                 write_unlock(&em_tree->lock);
 261
 262                 /* once for us */
 263                 free_extent_map(em);
 264                 /* once for the tree*/
 265                 free_extent_map(em);
 266         }
 267         if (split)
 268                 free_extent_map(split);
 269         if (split2)
 270                 free_extent_map(split2);
 271         return 0;
 272 }
 273
 274 /*
 275  * this is very complex, but the basic idea is to drop all extents
 276  * in the range start - end.  hint_block is filled in with a block number
 277  * that would be a good hint to the block allocator for this file.
 278  *
 279  * If an extent intersects the range but is not entirely inside the range
 280  * it is either truncated or split.  Anything entirely inside the range
 281  * is deleted from the tree.
 282  */
 283 int btrfs_drop_extents(struct btrfs_trans_handle *trans, struct inode *inode,
 284                        u64 start, u64 end, u64 *hint_byte, int drop_cache)
 285 {
 286         struct btrfs_root *root = BTRFS_I(inode)->root;
 287         struct extent_buffer *leaf;
 288         struct btrfs_file_extent_item *fi;
 289         struct btrfs_path *path;
 290         struct btrfs_key key;
 291         struct btrfs_key new_key;
 292         u64 search_start = start;
 293         u64 disk_bytenr = 0;
 294         u64 num_bytes = 0;
 295         u64 extent_offset = 0;
 296         u64 extent_end = 0;
 297         int del_nr = 0;
 298         int del_slot = 0;
 299         int extent_type;
 300         int recow;
 301         int ret;
 302
 303         if (drop_cache)
 304                 btrfs_drop_extent_cache(inode, start, end - 1, 0);
 305
 306         path = btrfs_alloc_path();
 307         if (!path)
 308                 return -ENOMEM;
 309
 310         while (1) {
 311                 recow = 0;
 312                 ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
 313                                                search_start, -1);
 314                 if (ret < 0)
 315                         break;
 316                 if (ret > 0 && path->slots[0] > 0 && search_start == start) {
 317                         leaf = path->nodes[0];
 318                         btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 319                         if (key.objectid == inode->i_ino &&
 320                             key.type == BTRFS_EXTENT_DATA_KEY)
 321                                 path->slots[0]--;
 322                 }
 323                 ret = 0;
 324 next_slot:
 325                 leaf = path->nodes[0];
 326                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 327                         BUG_ON(del_nr > 0);
 328                         ret = btrfs_next_leaf(root, path);
 329                         if (ret < 0)
 330                                 break;
 331                         if (ret > 0) {
 332                                 ret = 0;
 333                                 break;
 334                         }
 335                         leaf = path->nodes[0];
 336                         recow = 1;
 337                 }
 338
 339                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 340                 if (key.objectid > inode->i_ino ||
 341                     key.type > BTRFS_EXTENT_DATA_KEY || key.offset >= end)
 342                         break;
 343
 344                 fi = btrfs_item_ptr(leaf, path->slots[0],
 345                                     struct btrfs_file_extent_item);
 346                 extent_type = btrfs_file_extent_type(leaf, fi);
 347
 348                 if (extent_type == BTRFS_FILE_EXTENT_REG ||
 349                     extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
 350                         disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 351                         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
 352                         extent_offset = btrfs_file_extent_offset(leaf, fi);
 353                         extent_end = key.offset +
 354                                 btrfs_file_extent_num_bytes(leaf, fi);
 355                 } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 356                         extent_end = key.offset +
 357                                 btrfs_file_extent_inline_len(leaf, fi);
 358                 } else {
 359                         WARN_ON(1);
 360                         extent_end = search_start;
 361                 }
 362
 363                 if (extent_end <= search_start) {
 364                         path->slots[0]++;
 365                         goto next_slot;
 366                 }
 367
 368                 search_start = max(key.offset, start);
 369                 if (recow) {
 370                         btrfs_release_path(root, path);
 371                         continue;
 372                 }
 373
 374                 /*
 375                  *     | - range to drop - |
 376                  *  | -------- extent -------- |
 377                  */
 378                 if (start > key.offset && end < extent_end) {
 379                         BUG_ON(del_nr > 0);
 380                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 381
 382                         memcpy(&new_key, &key, sizeof(new_key));
 383                         new_key.offset = start;
 384                         ret = btrfs_duplicate_item(trans, root, path,
 385                                                    &new_key);
 386                         if (ret == -EAGAIN) {
 387                                 btrfs_release_path(root, path);
 388                                 continue;
 389                         }
 390                         if (ret < 0)
 391                                 break;
 392
 393                         leaf = path->nodes[0];
 394                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
 395                                             struct btrfs_file_extent_item);
 396                         btrfs_set_file_extent_num_bytes(leaf, fi,
 397                                                         start - key.offset);
 398
 399                         fi = btrfs_item_ptr(leaf, path->slots[0],
 400                                             struct btrfs_file_extent_item);
 401
 402                         extent_offset += start - key.offset;
 403                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
 404                         btrfs_set_file_extent_num_bytes(leaf, fi,
 405                                                         extent_end - start);
 406                         btrfs_mark_buffer_dirty(leaf);
 407
 408                         if (disk_bytenr > 0) {
 409                                 ret = btrfs_inc_extent_ref(trans, root,
 410                                                 disk_bytenr, num_bytes, 0,
 411                                                 root->root_key.objectid,
 412                                                 new_key.objectid,
 413                                                 start - extent_offset);
 414                                 BUG_ON(ret);
 415                                 *hint_byte = disk_bytenr;
 416                         }
 417                         key.offset = start;
 418                 }
 419                 /*
 420                  *  | ---- range to drop ----- |
 421                  *      | -------- extent -------- |
 422                  */
 423                 if (start <= key.offset && end < extent_end) {
 424                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 425
 426                         memcpy(&new_key, &key, sizeof(new_key));
 427                         new_key.offset = end;
 428                         btrfs_set_item_key_safe(trans, root, path, &new_key);
 429
 430                         extent_offset += end - key.offset;
 431                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
 432                         btrfs_set_file_extent_num_bytes(leaf, fi,
 433                                                         extent_end - end);
 434                         btrfs_mark_buffer_dirty(leaf);
 435                         if (disk_bytenr > 0) {
 436                                 inode_sub_bytes(inode, end - key.offset);
 437                                 *hint_byte = disk_bytenr;
 438                         }
 439                         break;
 440                 }
 441
 442                 search_start = extent_end;
 443                 /*
 444                  *       | ---- range to drop ----- |
 445                  *  | -------- extent -------- |
 446                  */
 447                 if (start > key.offset && end >= extent_end) {
 448                         BUG_ON(del_nr > 0);
 449                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 450
 451                         btrfs_set_file_extent_num_bytes(leaf, fi,
 452                                                         start - key.offset);
 453                         btrfs_mark_buffer_dirty(leaf);
 454                         if (disk_bytenr > 0) {
 455                                 inode_sub_bytes(inode, extent_end - start);
 456                                 *hint_byte = disk_bytenr;
 457                         }
 458                         if (end == extent_end)
 459                                 break;
 460
 461                         path->slots[0]++;
 462                         goto next_slot;
 463                 }
 464
 465                 /*
 466                  *  | ---- range to drop ----- |
 467                  *    | ------ extent ------ |
 468                  */
 469                 if (start <= key.offset && end >= extent_end) {
 470                         if (del_nr == 0) {
 471                                 del_slot = path->slots[0];
 472                                 del_nr = 1;
 473                         } else {
 474                                 BUG_ON(del_slot + del_nr != path->slots[0]);
 475                                 del_nr++;
 476                         }
 477
 478                         if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 479                                 inode_sub_bytes(inode,
 480                                                 extent_end - key.offset);
 481                                 extent_end = ALIGN(extent_end,
 482                                                    root->sectorsize);
 483                         } else if (disk_bytenr > 0) {
 484                                 ret = btrfs_free_extent(trans, root,
 485                                                 disk_bytenr, num_bytes, 0,
 486                                                 root->root_key.objectid,
 487                                                 key.objectid, key.offset -
 488                                                 extent_offset);
 489                                 BUG_ON(ret);
 490                                 inode_sub_bytes(inode,
 491                                                 extent_end - key.offset);
 492                                 *hint_byte = disk_bytenr;
 493                         }
 494
 495                         if (end == extent_end)
 496                                 break;
 497
 498                         if (path->slots[0] + 1 < btrfs_header_nritems(leaf)) {
 499                                 path->slots[0]++;
 500                                 goto next_slot;
 501                         }
 502
 503                         ret = btrfs_del_items(trans, root, path, del_slot,
 504                                               del_nr);
 505                         BUG_ON(ret);
 506
 507                         del_nr = 0;
 508                         del_slot = 0;
 509
 510                         btrfs_release_path(root, path);
 511                         continue;
 512                 }
 513
 514                 BUG_ON(1);
 515         }
 516
 517         if (del_nr > 0) {
 518                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
 519                 BUG_ON(ret);
 520         }
 521
 522         btrfs_free_path(path);
 523         return ret;
 524 }
 525
 526 static int extent_mergeable(struct extent_buffer *leaf, int slot,
 527                             u64 objectid, u64 bytenr, u64 orig_offset,
 528                             u64 *start, u64 *end)
 529 {
 530         struct btrfs_file_extent_item *fi;
 531         struct btrfs_key key;
 532         u64 extent_end;
 533
 534         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
 535                 return 0;
 536
 537         btrfs_item_key_to_cpu(leaf, &key, slot);
 538         if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
 539                 return 0;
 540
 541         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
 542         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
 543             btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
 544             btrfs_file_extent_offset(leaf, fi) != key.offset - orig_offset ||
 545             btrfs_file_extent_compression(leaf, fi) ||
 546             btrfs_file_extent_encryption(leaf, fi) ||
 547             btrfs_file_extent_other_encoding(leaf, fi))
 548                 return 0;
 549
 550         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 551         if ((*start && *start != key.offset) || (*end && *end != extent_end))
 552                 return 0;
 553
 554         *start = key.offset;
 555         *end = extent_end;
 556         return 1;
 557 }
 558
 559 /*
 560  * Mark extent in the range start - end as written.
 561  *
 562  * This changes extent type from 'pre-allocated' to 'regular'. If only
 563  * part of extent is marked as written, the extent will be split into
 564  * two or three.
 565  */
 566 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
 567                               struct inode *inode, u64 start, u64 end)
 568 {
 569         struct btrfs_root *root = BTRFS_I(inode)->root;
 570         struct extent_buffer *leaf;
 571         struct btrfs_path *path;
 572         struct btrfs_file_extent_item *fi;
 573         struct btrfs_key key;
 574         struct btrfs_key new_key;
 575         u64 bytenr;
 576         u64 num_bytes;
 577         u64 extent_end;
 578         u64 orig_offset;
 579         u64 other_start;
 580         u64 other_end;
 581         u64 split;
 582         int del_nr = 0;
 583         int del_slot = 0;
 584         int recow;
 585         int ret;
 586
 587         btrfs_drop_extent_cache(inode, start, end - 1, 0);
 588
 589         path = btrfs_alloc_path();
 590         BUG_ON(!path);
 591 again:
 592         recow = 0;
 593         split = start;
 594         key.objectid = inode->i_ino;
 595         key.type = BTRFS_EXTENT_DATA_KEY;
 596         key.offset = split;
 597
 598         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 599         if (ret > 0 && path->slots[0] > 0)
 600                 path->slots[0]--;
 601
 602         leaf = path->nodes[0];
 603         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 604         BUG_ON(key.objectid != inode->i_ino ||
 605                key.type != BTRFS_EXTENT_DATA_KEY);
 606         fi = btrfs_item_ptr(leaf, path->slots[0],
 607                             struct btrfs_file_extent_item);
 608         BUG_ON(btrfs_file_extent_type(leaf, fi) !=
 609                BTRFS_FILE_EXTENT_PREALLOC);
 610         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 611         BUG_ON(key.offset > start || extent_end < end);
 612
 613         bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 614         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
 615         orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
 616         memcpy(&new_key, &key, sizeof(new_key));
 617
 618         if (start == key.offset && end < extent_end) {
 619                 other_start = 0;
 620                 other_end = start;
 621                 if (extent_mergeable(leaf, path->slots[0] - 1,
 622                                      inode->i_ino, bytenr, orig_offset,
 623                                      &other_start, &other_end)) {
 624                         new_key.offset = end;
 625                         btrfs_set_item_key_safe(trans, root, path, &new_key);
 626                         fi = btrfs_item_ptr(leaf, path->slots[0],
 627                                             struct btrfs_file_extent_item);
 628                         btrfs_set_file_extent_num_bytes(leaf, fi,
 629                                                         extent_end - end);
 630                         btrfs_set_file_extent_offset(leaf, fi,
 631                                                      end - orig_offset);
 632                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
 633                                             struct btrfs_file_extent_item);
 634                         btrfs_set_file_extent_num_bytes(leaf, fi,
 635                                                         end - other_start);
 636                         btrfs_mark_buffer_dirty(leaf);
 637                         goto out;
 638                 }
 639         }
 640
 641         if (start > key.offset && end == extent_end) {
 642                 other_start = end;
 643                 other_end = 0;
 644                 if (extent_mergeable(leaf, path->slots[0] + 1,
 645                                      inode->i_ino, bytenr, orig_offset,
 646                                      &other_start, &other_end)) {
 647                         fi = btrfs_item_ptr(leaf, path->slots[0],
 648                                             struct btrfs_file_extent_item);
 649                         btrfs_set_file_extent_num_bytes(leaf, fi,
 650                                                         start - key.offset);
 651                         path->slots[0]++;
 652                         new_key.offset = start;
 653                         btrfs_set_item_key_safe(trans, root, path, &new_key);
 654
 655                         fi = btrfs_item_ptr(leaf, path->slots[0],
 656                                             struct btrfs_file_extent_item);
 657                         btrfs_set_file_extent_num_bytes(leaf, fi,
 658                                                         other_end - start);
 659                         btrfs_set_file_extent_offset(leaf, fi,
 660                                                      start - orig_offset);
 661                         btrfs_mark_buffer_dirty(leaf);
 662                         goto out;
 663                 }
 664         }
 665
 666         while (start > key.offset || end < extent_end) {
 667                 if (key.offset == start)
 668                         split = end;
 669
 670                 new_key.offset = split;
 671                 ret = btrfs_duplicate_item(trans, root, path, &new_key);
 672                 if (ret == -EAGAIN) {
 673                         btrfs_release_path(root, path);
 674                         goto again;
 675                 }
 676                 BUG_ON(ret < 0);
 677
 678                 leaf = path->nodes[0];
 679                 fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
 680                                     struct btrfs_file_extent_item);
 681                 btrfs_set_file_extent_num_bytes(leaf, fi,
 682                                                 split - key.offset);
 683
 684                 fi = btrfs_item_ptr(leaf, path->slots[0],
 685                                     struct btrfs_file_extent_item);
 686
 687                 btrfs_set_file_extent_offset(leaf, fi, split - orig_offset);
 688                 btrfs_set_file_extent_num_bytes(leaf, fi,
 689                                                 extent_end - split);
 690                 btrfs_mark_buffer_dirty(leaf);
 691
 692                 ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
 693                                            root->root_key.objectid,
 694                                            inode->i_ino, orig_offset);
 695                 BUG_ON(ret);
 696
 697                 if (split == start) {
 698                         key.offset = start;
 699                 } else {
 700                         BUG_ON(start != key.offset);
 701                         path->slots[0]--;
 702                         extent_end = end;
 703                 }
 704                 recow = 1;
 705         }
 706
 707         other_start = end;
 708         other_end = 0;
 709         if (extent_mergeable(leaf, path->slots[0] + 1,
 710                              inode->i_ino, bytenr, orig_offset,
 711                              &other_start, &other_end)) {
 712                 if (recow) {
 713                         btrfs_release_path(root, path);
 714                         goto again;
 715                 }
 716                 extent_end = other_end;
 717                 del_slot = path->slots[0] + 1;
 718                 del_nr++;
 719                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
 720                                         0, root->root_key.objectid,
 721                                         inode->i_ino, orig_offset);
 722                 BUG_ON(ret);
 723         }
 724         other_start = 0;
 725         other_end = start;
 726         if (extent_mergeable(leaf, path->slots[0] - 1,
 727                              inode->i_ino, bytenr, orig_offset,
 728                              &other_start, &other_end)) {
 729                 if (recow) {
 730                         btrfs_release_path(root, path);
 731                         goto again;
 732                 }
 733                 key.offset = other_start;
 734                 del_slot = path->slots[0];
 735                 del_nr++;
 736                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
 737                                         0, root->root_key.objectid,
 738                                         inode->i_ino, orig_offset);
 739                 BUG_ON(ret);
 740         }
 741         if (del_nr == 0) {
 742                 fi = btrfs_item_ptr(leaf, path->slots[0],
 743                            struct btrfs_file_extent_item);
 744                 btrfs_set_file_extent_type(leaf, fi,
 745                                            BTRFS_FILE_EXTENT_REG);
 746                 btrfs_mark_buffer_dirty(leaf);
 747         } else {
 748                 fi = btrfs_item_ptr(leaf, del_slot - 1,
 749                            struct btrfs_file_extent_item);
 750                 btrfs_set_file_extent_type(leaf, fi,
 751                                            BTRFS_FILE_EXTENT_REG);
 752                 btrfs_set_file_extent_num_bytes(leaf, fi,
 753                                                 extent_end - key.offset);
 754                 btrfs_mark_buffer_dirty(leaf);
 755
 756                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
 757                 BUG_ON(ret);
 758         }
 759 out:
 760         btrfs_free_path(path);
 761         return 0;
 762 }
 763
 764 /*
 765  * this gets pages into the page cache and locks them down, it also properly
 766  * waits for data=ordered extents to finish before allowing the pages to be
 767  * modified.
 768  */
 769 static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
 770                          struct page **pages, size_t num_pages,
 771                          loff_t pos, unsigned long first_index,
 772                          unsigned long last_index, size_t write_bytes)
 773 {
 774         struct extent_state *cached_state = NULL;
 775         int i;
 776         unsigned long index = pos >> PAGE_CACHE_SHIFT;
 777         struct inode *inode = fdentry(file)->d_inode;
 778         int err = 0;
 779         u64 start_pos;
 780         u64 last_pos;
 781
 782         start_pos = pos & ~((u64)root->sectorsize - 1);
 783         last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
 784
 785         if (start_pos > inode->i_size) {
 786                 err = btrfs_cont_expand(inode, start_pos);
 787                 if (err)
 788                         return err;
 789         }
 790
 791         memset(pages, 0, num_pages * sizeof(struct page *));
 792 again:
 793         for (i = 0; i < num_pages; i++) {
 794                 pages[i] = grab_cache_page(inode->i_mapping, index + i);
 795                 if (!pages[i]) {
 796                         err = -ENOMEM;
 797                         BUG_ON(1);
 798                 }
 799                 wait_on_page_writeback(pages[i]);
 800         }
 801         if (start_pos < inode->i_size) {
 802                 struct btrfs_ordered_extent *ordered;
 803                 lock_extent_bits(&BTRFS_I(inode)->io_tree,
 804                                  start_pos, last_pos - 1, 0, &cached_state,
 805                                  GFP_NOFS);
 806                 ordered = btrfs_lookup_first_ordered_extent(inode,
 807                                                             last_pos - 1);
 808                 if (ordered &&
 809                     ordered->file_offset + ordered->len > start_pos &&
 810                     ordered->file_offset < last_pos) {
 811                         btrfs_put_ordered_extent(ordered);
 812                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
 813                                              start_pos, last_pos - 1,
 814                                              &cached_state, GFP_NOFS);
 815                         for (i = 0; i < num_pages; i++) {
 816                                 unlock_page(pages[i]);
 817                                 page_cache_release(pages[i]);
 818                         }
 819                         btrfs_wait_ordered_range(inode, start_pos,
 820                                                  last_pos - start_pos);
 821                         goto again;
 822                 }
 823                 if (ordered)
 824                         btrfs_put_ordered_extent(ordered);
 825
 826                 clear_extent_bit(&BTRFS_I(inode)->io_tree, start_pos,
 827                                   last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC |
 828                                   EXTENT_DO_ACCOUNTING, 0, 0, &cached_state,
 829                                   GFP_NOFS);
 830                 unlock_extent_cached(&BTRFS_I(inode)->io_tree,
 831                                      start_pos, last_pos - 1, &cached_state,
 832                                      GFP_NOFS);
 833         }
 834         for (i = 0; i < num_pages; i++) {
 835                 clear_page_dirty_for_io(pages[i]);
 836                 set_page_extent_mapped(pages[i]);
 837                 WARN_ON(!PageLocked(pages[i]));
 838         }
 839         return 0;
 840 }
 841
 842 static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
 843                                     const struct iovec *iov,
 844                                     unsigned long nr_segs, loff_t pos)
 845 {
 846         struct file *file = iocb->ki_filp;
 847         struct inode *inode = fdentry(file)->d_inode;
 848         struct btrfs_root *root = BTRFS_I(inode)->root;
 849         struct page *pinned[2];
 850         struct page **pages = NULL;
 851         struct iov_iter i;
 852         loff_t *ppos = &iocb->ki_pos;
 853         loff_t start_pos;
 854         ssize_t num_written = 0;
 855         ssize_t err = 0;
 856         size_t count;
 857         size_t ocount;
 858         int ret = 0;
 859         int nrptrs;
 860         unsigned long first_index;
 861         unsigned long last_index;
 862         int will_write;
 863         int buffered = 0;
 864         int copied = 0;
 865         int dirty_pages = 0;
 866
 867         will_write = ((file->f_flags & O_DSYNC) || IS_SYNC(inode) ||
 868                       (file->f_flags & O_DIRECT));
 869
 870         pinned[0] = NULL;
 871         pinned[1] = NULL;
 872
 873         start_pos = pos;
 874
 875         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
 876
 877         mutex_lock(&inode->i_mutex);
 878
 879         err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
 880         if (err)
 881                 goto out;
 882         count = ocount;
 883
 884         current->backing_dev_info = inode->i_mapping->backing_dev_info;
 885         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
 886         if (err)
 887                 goto out;
 888
 889         if (count == 0)
 890                 goto out;
 891
 892         err = file_remove_suid(file);
 893         if (err)
 894                 goto out;
 895
 896         /*
 897          * If BTRFS flips readonly due to some impossible error
 898          * (fs_info->fs_state now has BTRFS_SUPER_FLAG_ERROR),
 899          * although we have opened a file as writable, we have
 900          * to stop this write operation to ensure FS consistency.
 901          */
 902         if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
 903                 err = -EROFS;
 904                 goto out;
 905         }
 906
 907         file_update_time(file);
 908         BTRFS_I(inode)->sequence++;
 909
 910         if (unlikely(file->f_flags & O_DIRECT)) {
 911                 num_written = generic_file_direct_write(iocb, iov, &nr_segs,
 912                                                         pos, ppos, count,
 913                                                         ocount);
 914                 /*
 915                  * the generic O_DIRECT will update in-memory i_size after the
 916                  * DIOs are done.  But our endio handlers that update the on
 917                  * disk i_size never update past the in memory i_size.  So we
 918                  * need one more update here to catch any additions to the
 919                  * file
 920                  */
 921                 if (inode->i_size != BTRFS_I(inode)->disk_i_size) {
 922                         btrfs_ordered_update_i_size(inode, inode->i_size, NULL);
 923                         mark_inode_dirty(inode);
 924                 }
 925
 926                 if (num_written < 0) {
 927                         ret = num_written;
 928                         num_written = 0;
 929                         goto out;
 930                 } else if (num_written == count) {
 931                         /* pick up pos changes done by the generic code */
 932                         pos = *ppos;
 933                         goto out;
 934                 }
 935                 /*
 936                  * We are going to do buffered for the rest of the range, so we
 937                  * need to make sure to invalidate the buffered pages when we're
 938                  * done.
 939                  */
 940                 buffered = 1;
 941                 pos += num_written;
 942         }
 943
 944         iov_iter_init(&i, iov, nr_segs, count, num_written);
 945         nrptrs = min((iov_iter_count(&i) + PAGE_CACHE_SIZE - 1) /
 946                      PAGE_CACHE_SIZE, PAGE_CACHE_SIZE /
 947                      (sizeof(struct page *)));
 948         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
 949
 950         /* generic_write_checks can change our pos */
 951         start_pos = pos;
 952
 953         first_index = pos >> PAGE_CACHE_SHIFT;
 954         last_index = (pos + iov_iter_count(&i)) >> PAGE_CACHE_SHIFT;
 955
 956         /*
 957          * there are lots of better ways to do this, but this code
 958          * makes sure the first and last page in the file range are
 959          * up to date and ready for cow
 960          */
 961         if ((pos & (PAGE_CACHE_SIZE - 1))) {
 962                 pinned[0] = grab_cache_page(inode->i_mapping, first_index);
 963                 if (!PageUptodate(pinned[0])) {
 964                         ret = btrfs_readpage(NULL, pinned[0]);
 965                         BUG_ON(ret);
 966                         wait_on_page_locked(pinned[0]);
 967                 } else {
 968                         unlock_page(pinned[0]);
 969                 }
 970         }
 971         if ((pos + iov_iter_count(&i)) & (PAGE_CACHE_SIZE - 1)) {
 972                 pinned[1] = grab_cache_page(inode->i_mapping, last_index);
 973                 if (!PageUptodate(pinned[1])) {
 974                         ret = btrfs_readpage(NULL, pinned[1]);
 975                         BUG_ON(ret);
 976                         wait_on_page_locked(pinned[1]);
 977                 } else {
 978                         unlock_page(pinned[1]);
 979                 }
 980         }
 981
 982         while (iov_iter_count(&i) > 0) {
 983                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
 984                 size_t write_bytes = min(iov_iter_count(&i),
 985                                          nrptrs * (size_t)PAGE_CACHE_SIZE -
 986                                          offset);
 987                 size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
 988                                         PAGE_CACHE_SHIFT;
 989
 990                 WARN_ON(num_pages > nrptrs);
 991                 memset(pages, 0, sizeof(struct page *) * nrptrs);
 992
 993                 /*
 994                  * Fault pages before locking them in prepare_pages
 995                  * to avoid recursive lock
 996                  */
 997                 if (unlikely(iov_iter_fault_in_readable(&i, write_bytes))) {
 998                         ret = -EFAULT;
 999                         goto out;
1000                 }
1001
1002                 ret = btrfs_delalloc_reserve_space(inode,
1003                                         num_pages << PAGE_CACHE_SHIFT);
1004                 if (ret)
1005                         goto out;
1006
1007                 ret = prepare_pages(root, file, pages, num_pages,
1008                                     pos, first_index, last_index,
1009                                     write_bytes);
1010                 if (ret) {
1011                         btrfs_delalloc_release_space(inode,
1012                                         num_pages << PAGE_CACHE_SHIFT);
1013                         goto out;
1014                 }
1015
1016                 copied = btrfs_copy_from_user(pos, num_pages,
1017                                            write_bytes, pages, &i);
1018                 dirty_pages = (copied + PAGE_CACHE_SIZE - 1) >>
1019                                         PAGE_CACHE_SHIFT;
1020
1021                 if (num_pages > dirty_pages) {
1022                         if (copied > 0)
1023                                 atomic_inc(
1024                                         &BTRFS_I(inode)->outstanding_extents);
1025                         btrfs_delalloc_release_space(inode,
1026                                         (num_pages - dirty_pages) <<
1027                                         PAGE_CACHE_SHIFT);
1028                 }
1029
1030                 if (copied > 0) {
1031                         dirty_and_release_pages(NULL, root, file, pages,
1032                                                 dirty_pages, pos, copied);
1033                 }
1034
1035                 btrfs_drop_pages(pages, num_pages);
1036
1037                 if (copied > 0) {
1038                         if (will_write) {
1039                                 filemap_fdatawrite_range(inode->i_mapping, pos,
1040                                                          pos + copied - 1);
1041                         } else {
1042                                 balance_dirty_pages_ratelimited_nr(
1043                                                         inode->i_mapping,
1044                                                         dirty_pages);
1045                                 if (dirty_pages <
1046                                 (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
1047                                         btrfs_btree_balance_dirty(root, 1);
1048                                 btrfs_throttle(root);
1049                         }
1050                 }
1051
1052                 pos += copied;
1053                 num_written += copied;
1054
1055                 cond_resched();
1056         }
1057 out:
1058         mutex_unlock(&inode->i_mutex);
1059         if (ret)
1060                 err = ret;
1061
1062         kfree(pages);
1063         if (pinned[0])
1064                 page_cache_release(pinned[0]);
1065         if (pinned[1])
1066                 page_cache_release(pinned[1]);
1067         *ppos = pos;
1068
1069         /*
1070          * we want to make sure fsync finds this change
1071          * but we haven't joined a transaction running right now.
1072          *
1073          * Later on, someone is sure to update the inode and get the
1074          * real transid recorded.
1075          *
1076          * We set last_trans now to the fs_info generation + 1,
1077          * this will either be one more than the running transaction
1078          * or the generation used for the next transaction if there isn't
1079          * one running right now.
1080          */
1081         BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
1082
1083         if (num_written > 0 && will_write) {
1084                 struct btrfs_trans_handle *trans;
1085
1086                 err = btrfs_wait_ordered_range(inode, start_pos, num_written);
1087                 if (err)
1088                         num_written = err;
1089
1090                 if ((file->f_flags & O_DSYNC) || IS_SYNC(inode)) {
1091                         trans = btrfs_start_transaction(root, 0);
1092                         if (IS_ERR(trans)) {
1093                                 num_written = PTR_ERR(trans);
1094                                 goto done;
1095                         }
1096                         mutex_lock(&inode->i_mutex);
1097                         ret = btrfs_log_dentry_safe(trans, root,
1098                                                     file->f_dentry);
1099                         mutex_unlock(&inode->i_mutex);
1100                         if (ret == 0) {
1101                                 ret = btrfs_sync_log(trans, root);
1102                                 if (ret == 0)
1103                                         btrfs_end_transaction(trans, root);
1104                                 else
1105                                         btrfs_commit_transaction(trans, root);
1106                         } else if (ret != BTRFS_NO_LOG_SYNC) {
1107                                 btrfs_commit_transaction(trans, root);
1108                         } else {
1109                                 btrfs_end_transaction(trans, root);
1110                         }
1111                 }
1112                 if (file->f_flags & O_DIRECT && buffered) {
1113                         invalidate_mapping_pages(inode->i_mapping,
1114                               start_pos >> PAGE_CACHE_SHIFT,
1115                              (start_pos + num_written - 1) >> PAGE_CACHE_SHIFT);
1116                 }
1117         }
1118 done:
1119         current->backing_dev_info = NULL;
1120         return num_written ? num_written : err;
1121 }
1122
1123 int btrfs_release_file(struct inode *inode, struct file *filp)
1124 {
1125         /*
1126          * ordered_data_close is set by settattr when we are about to truncate
1127          * a file from a non-zero size to a zero size.  This tries to
1128          * flush down new bytes that may have been written if the
1129          * application were using truncate to replace a file in place.
1130          */
1131         if (BTRFS_I(inode)->ordered_data_close) {
1132                 BTRFS_I(inode)->ordered_data_close = 0;
1133                 btrfs_add_ordered_operation(NULL, BTRFS_I(inode)->root, inode);
1134                 if (inode->i_size > BTRFS_ORDERED_OPERATIONS_FLUSH_LIMIT)
1135                         filemap_flush(inode->i_mapping);
1136         }
1137         if (filp->private_data)
1138                 btrfs_ioctl_trans_end(filp);
1139         return 0;
1140 }
1141
1142 /*
1143  * fsync call for both files and directories.  This logs the inode into
1144  * the tree log instead of forcing full commits whenever possible.
1145  *
1146  * It needs to call filemap_fdatawait so that all ordered extent updates are
1147  * in the metadata btree are up to date for copying to the log.
1148  *
1149  * It drops the inode mutex before doing the tree log commit.  This is an
1150  * important optimization for directories because holding the mutex prevents
1151  * new operations on the dir while we write to disk.
1152  */
1153 int btrfs_sync_file(struct file *file, int datasync)
1154 {
1155         struct dentry *dentry = file->f_path.dentry;
1156         struct inode *inode = dentry->d_inode;
1157         struct btrfs_root *root = BTRFS_I(inode)->root;
1158         int ret = 0;
1159         struct btrfs_trans_handle *trans;
1160
1161
1162         /* we wait first, since the writeback may change the inode */
1163         root->log_batch++;
1164         /* the VFS called filemap_fdatawrite for us */
1165         btrfs_wait_ordered_range(inode, 0, (u64)-1);
1166         root->log_batch++;
1167
1168         /*
1169          * check the transaction that last modified this inode
1170          * and see if its already been committed
1171          */
1172         if (!BTRFS_I(inode)->last_trans)
1173                 goto out;
1174
1175         /*
1176          * if the last transaction that changed this file was before
1177          * the current transaction, we can bail out now without any
1178          * syncing
1179          */
1180         mutex_lock(&root->fs_info->trans_mutex);
1181         if (BTRFS_I(inode)->last_trans <=
1182             root->fs_info->last_trans_committed) {
1183                 BTRFS_I(inode)->last_trans = 0;
1184                 mutex_unlock(&root->fs_info->trans_mutex);
1185                 goto out;
1186         }
1187         mutex_unlock(&root->fs_info->trans_mutex);
1188
1189         /*
1190          * ok we haven't committed the transaction yet, lets do a commit
1191          */
1192         if (file->private_data)
1193                 btrfs_ioctl_trans_end(file);
1194
1195         trans = btrfs_start_transaction(root, 0);
1196         if (IS_ERR(trans)) {
1197                 ret = PTR_ERR(trans);
1198                 goto out;
1199         }
1200
1201         ret = btrfs_log_dentry_safe(trans, root, dentry);
1202         if (ret < 0)
1203                 goto out;
1204
1205         /* we've logged all the items and now have a consistent
1206          * version of the file in the log.  It is possible that
1207          * someone will come in and modify the file, but that's
1208          * fine because the log is consistent on disk, and we
1209          * have references to all of the file's extents
1210          *
1211          * It is possible that someone will come in and log the
1212          * file again, but that will end up using the synchronization
1213          * inside btrfs_sync_log to keep things safe.
1214          */
1215         mutex_unlock(&dentry->d_inode->i_mutex);
1216
1217         if (ret != BTRFS_NO_LOG_SYNC) {
1218                 if (ret > 0) {
1219                         ret = btrfs_commit_transaction(trans, root);
1220                 } else {
1221                         ret = btrfs_sync_log(trans, root);
1222                         if (ret == 0)
1223                                 ret = btrfs_end_transaction(trans, root);
1224                         else
1225                                 ret = btrfs_commit_transaction(trans, root);
1226                 }
1227         } else {
1228                 ret = btrfs_end_transaction(trans, root);
1229         }
1230         mutex_lock(&dentry->d_inode->i_mutex);
1231 out:
1232         return ret > 0 ? -EIO : ret;
1233 }
1234
1235 static const struct vm_operations_struct btrfs_file_vm_ops = {
1236         .fault          = filemap_fault,
1237         .page_mkwrite   = btrfs_page_mkwrite,
1238 };
1239
1240 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
1241 {
1242         struct address_space *mapping = filp->f_mapping;
1243
1244         if (!mapping->a_ops->readpage)
1245                 return -ENOEXEC;
1246
1247         file_accessed(filp);
1248         vma->vm_ops = &btrfs_file_vm_ops;
1249         vma->vm_flags |= VM_CAN_NONLINEAR;
1250
1251         return 0;
1252 }
1253
1254 static long btrfs_fallocate(struct file *file, int mode,
1255                             loff_t offset, loff_t len)
1256 {
1257         struct inode *inode = file->f_path.dentry->d_inode;
1258         struct extent_state *cached_state = NULL;
1259         u64 cur_offset;
1260         u64 last_byte;
1261         u64 alloc_start;
1262         u64 alloc_end;
1263         u64 alloc_hint = 0;
1264         u64 locked_end;
1265         u64 mask = BTRFS_I(inode)->root->sectorsize - 1;
1266         struct extent_map *em;
1267         int ret;
1268
1269         alloc_start = offset & ~mask;
1270         alloc_end =  (offset + len + mask) & ~mask;
1271
1272         /* We only support the FALLOC_FL_KEEP_SIZE mode */
1273         if (mode & ~FALLOC_FL_KEEP_SIZE)
1274                 return -EOPNOTSUPP;
1275
1276         /*
1277          * wait for ordered IO before we have any locks.  We'll loop again
1278          * below with the locks held.
1279          */
1280         btrfs_wait_ordered_range(inode, alloc_start, alloc_end - alloc_start);
1281
1282         mutex_lock(&inode->i_mutex);
1283         ret = inode_newsize_ok(inode, alloc_end);
1284         if (ret)
1285                 goto out;
1286
1287         if (alloc_start > inode->i_size) {
1288                 ret = btrfs_cont_expand(inode, alloc_start);
1289                 if (ret)
1290                         goto out;
1291         }
1292
1293         ret = btrfs_check_data_free_space(inode, alloc_end - alloc_start);
1294         if (ret)
1295                 goto out;
1296
1297         locked_end = alloc_end - 1;
1298         while (1) {
1299                 struct btrfs_ordered_extent *ordered;
1300
1301                 /* the extent lock is ordered inside the running
1302                  * transaction
1303                  */
1304                 lock_extent_bits(&BTRFS_I(inode)->io_tree, alloc_start,
1305                                  locked_end, 0, &cached_state, GFP_NOFS);
1306                 ordered = btrfs_lookup_first_ordered_extent(inode,
1307                                                             alloc_end - 1);
1308                 if (ordered &&
1309                     ordered->file_offset + ordered->len > alloc_start &&
1310                     ordered->file_offset < alloc_end) {
1311                         btrfs_put_ordered_extent(ordered);
1312                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1313                                              alloc_start, locked_end,
1314                                              &cached_state, GFP_NOFS);
1315                         /*
1316                          * we can't wait on the range with the transaction
1317                          * running or with the extent lock held
1318                          */
1319                         btrfs_wait_ordered_range(inode, alloc_start,
1320                                                  alloc_end - alloc_start);
1321                 } else {
1322                         if (ordered)
1323                                 btrfs_put_ordered_extent(ordered);
1324                         break;
1325                 }
1326         }
1327
1328         cur_offset = alloc_start;
1329         while (1) {
1330                 em = btrfs_get_extent(inode, NULL, 0, cur_offset,
1331                                       alloc_end - cur_offset, 0);
1332                 BUG_ON(IS_ERR(em) || !em);
1333                 last_byte = min(extent_map_end(em), alloc_end);
1334                 last_byte = (last_byte + mask) & ~mask;
1335                 if (em->block_start == EXTENT_MAP_HOLE ||
1336                     (cur_offset >= inode->i_size &&
1337                      !test_bit(EXTENT_FLAG_PREALLOC, &em->flags))) {
1338                         ret = btrfs_prealloc_file_range(inode, mode, cur_offset,
1339                                                         last_byte - cur_offset,
1340                                                         1 << inode->i_blkbits,
1341                                                         offset + len,
1342                                                         &alloc_hint);
1343                         if (ret < 0) {
1344                                 free_extent_map(em);
1345                                 break;
1346                         }
1347                 }
1348                 free_extent_map(em);
1349
1350                 cur_offset = last_byte;
1351                 if (cur_offset >= alloc_end) {
1352                         ret = 0;
1353                         break;
1354                 }
1355         }
1356         unlock_extent_cached(&BTRFS_I(inode)->io_tree, alloc_start, locked_end,
1357                              &cached_state, GFP_NOFS);
1358
1359         btrfs_free_reserved_data_space(inode, alloc_end - alloc_start);
1360 out:
1361         mutex_unlock(&inode->i_mutex);
1362         return ret;
1363 }
1364
1365 const struct file_operations btrfs_file_operations = {
1366         .llseek         = generic_file_llseek,
1367         .read           = do_sync_read,
1368         .write          = do_sync_write,
1369         .aio_read       = generic_file_aio_read,
1370         .splice_read    = generic_file_splice_read,
1371         .aio_write      = btrfs_file_aio_write,
1372         .mmap           = btrfs_file_mmap,
1373         .open           = generic_file_open,
1374         .release        = btrfs_release_file,
1375         .fsync          = btrfs_sync_file,
1376         .fallocate      = btrfs_fallocate,
1377         .unlocked_ioctl = btrfs_ioctl,
1378 #ifdef CONFIG_COMPAT
1379         .compat_ioctl   = btrfs_ioctl,
1380 #endif
1381 };