git.oblomov.eu Git - linux-2.6/blob - 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/smp_lock.h>
  26 #include <linux/backing-dev.h>
  27 #include <linux/mpage.h>
  28 #include <linux/swap.h>
  29 #include <linux/writeback.h>
  30 #include <linux/statfs.h>
  31 #include <linux/compat.h>
  32 #include "ctree.h"
  33 #include "disk-io.h"
  34 #include "transaction.h"
  35 #include "btrfs_inode.h"
  36 #include "ioctl.h"
  37 #include "print-tree.h"
  38 #include "tree-log.h"
  39 #include "locking.h"
  40 #include "compat.h"
  41
  42
  43 /* simple helper to fault in pages and copy.  This should go away
  44  * and be replaced with calls into generic code.
  45  */
  46 static noinline int btrfs_copy_from_user(loff_t pos, int num_pages,
  47                                          int write_bytes,
  48                                          struct page **prepared_pages,
  49                                          const char __user *buf)
  50 {
  51         long page_fault = 0;
  52         int i;
  53         int offset = pos & (PAGE_CACHE_SIZE - 1);
  54
  55         for (i = 0; i < num_pages && write_bytes > 0; i++, offset = 0) {
  56                 size_t count = min_t(size_t,
  57                                      PAGE_CACHE_SIZE - offset, write_bytes);
  58                 struct page *page = prepared_pages[i];
  59                 fault_in_pages_readable(buf, count);
  60
  61                 /* Copy data from userspace to the current page */
  62                 kmap(page);
  63                 page_fault = __copy_from_user(page_address(page) + offset,
  64                                               buf, count);
  65                 /* Flush processor's dcache for this page */
  66                 flush_dcache_page(page);
  67                 kunmap(page);
  68                 buf += count;
  69                 write_bytes -= count;
  70
  71                 if (page_fault)
  72                         break;
  73         }
  74         return page_fault ? -EFAULT : 0;
  75 }
  76
  77 /*
  78  * unlocks pages after btrfs_file_write is done with them
  79  */
  80 static noinline void btrfs_drop_pages(struct page **pages, size_t num_pages)
  81 {
  82         size_t i;
  83         for (i = 0; i < num_pages; i++) {
  84                 if (!pages[i])
  85                         break;
  86                 /* page checked is some magic around finding pages that
  87                  * have been modified without going through btrfs_set_page_dirty
  88                  * clear it here
  89                  */
  90                 ClearPageChecked(pages[i]);
  91                 unlock_page(pages[i]);
  92                 mark_page_accessed(pages[i]);
  93                 page_cache_release(pages[i]);
  94         }
  95 }
  96
  97 /*
  98  * after copy_from_user, pages need to be dirtied and we need to make
  99  * sure holes are created between the current EOF and the start of
 100  * any next extents (if required).
 101  *
 102  * this also makes the decision about creating an inline extent vs
 103  * doing real data extents, marking pages dirty and delalloc as required.
 104  */
 105 static noinline int dirty_and_release_pages(struct btrfs_trans_handle *trans,
 106                                    struct btrfs_root *root,
 107                                    struct file *file,
 108                                    struct page **pages,
 109                                    size_t num_pages,
 110                                    loff_t pos,
 111                                    size_t write_bytes)
 112 {
 113         int err = 0;
 114         int i;
 115         struct inode *inode = fdentry(file)->d_inode;
 116         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 117         u64 hint_byte;
 118         u64 num_bytes;
 119         u64 start_pos;
 120         u64 end_of_last_block;
 121         u64 end_pos = pos + write_bytes;
 122         loff_t isize = i_size_read(inode);
 123
 124         start_pos = pos & ~((u64)root->sectorsize - 1);
 125         num_bytes = (write_bytes + pos - start_pos +
 126                     root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
 127
 128         end_of_last_block = start_pos + num_bytes - 1;
 129
 130         lock_extent(io_tree, start_pos, end_of_last_block, GFP_NOFS);
 131         trans = btrfs_join_transaction(root, 1);
 132         if (!trans) {
 133                 err = -ENOMEM;
 134                 goto out_unlock;
 135         }
 136         btrfs_set_trans_block_group(trans, inode);
 137         hint_byte = 0;
 138
 139         set_extent_uptodate(io_tree, start_pos, end_of_last_block, GFP_NOFS);
 140
 141         /* check for reserved extents on each page, we don't want
 142          * to reset the delalloc bit on things that already have
 143          * extents reserved.
 144          */
 145         btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block);
 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                 btrfs_update_inode(trans, root, inode);
 155         }
 156         err = btrfs_end_transaction(trans, root);
 157 out_unlock:
 158         unlock_extent(io_tree, start_pos, end_of_last_block, GFP_NOFS);
 159         return err;
 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                 spin_lock(&em_tree->lock);
 191                 em = lookup_extent_mapping(em_tree, start, len);
 192                 if (!em) {
 193                         spin_unlock(&em_tree->lock);
 194                         break;
 195                 }
 196                 flags = em->flags;
 197                 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
 198                         spin_unlock(&em_tree->lock);
 199                         if (em->start <= start &&
 200                             (!testend || em->start + em->len >= start + len)) {
 201                                 free_extent_map(em);
 202                                 break;
 203                         }
 204                         if (start < em->start) {
 205                                 len = em->start - start;
 206                         } else {
 207                                 len = start + len - (em->start + em->len);
 208                                 start = em->start + em->len;
 209                         }
 210                         free_extent_map(em);
 211                         continue;
 212                 }
 213                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 214                 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
 215                 remove_extent_mapping(em_tree, em);
 216
 217                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 218                     em->start < start) {
 219                         split->start = em->start;
 220                         split->len = start - em->start;
 221                         split->orig_start = em->orig_start;
 222                         split->block_start = em->block_start;
 223
 224                         if (compressed)
 225                                 split->block_len = em->block_len;
 226                         else
 227                                 split->block_len = split->len;
 228
 229                         split->bdev = em->bdev;
 230                         split->flags = flags;
 231                         ret = add_extent_mapping(em_tree, split);
 232                         BUG_ON(ret);
 233                         free_extent_map(split);
 234                         split = split2;
 235                         split2 = NULL;
 236                 }
 237                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 238                     testend && em->start + em->len > start + len) {
 239                         u64 diff = start + len - em->start;
 240
 241                         split->start = start + len;
 242                         split->len = em->start + em->len - (start + len);
 243                         split->bdev = em->bdev;
 244                         split->flags = flags;
 245
 246                         if (compressed) {
 247                                 split->block_len = em->block_len;
 248                                 split->block_start = em->block_start;
 249                                 split->orig_start = em->orig_start;
 250                         } else {
 251                                 split->block_len = split->len;
 252                                 split->block_start = em->block_start + diff;
 253                                 split->orig_start = split->start;
 254                         }
 255
 256                         ret = add_extent_mapping(em_tree, split);
 257                         BUG_ON(ret);
 258                         free_extent_map(split);
 259                         split = NULL;
 260                 }
 261                 spin_unlock(&em_tree->lock);
 262
 263                 /* once for us */
 264                 free_extent_map(em);
 265                 /* once for the tree*/
 266                 free_extent_map(em);
 267         }
 268         if (split)
 269                 free_extent_map(split);
 270         if (split2)
 271                 free_extent_map(split2);
 272         return 0;
 273 }
 274
 275 int btrfs_check_file(struct btrfs_root *root, struct inode *inode)
 276 {
 277         return 0;
 278 #if 0
 279         struct btrfs_path *path;
 280         struct btrfs_key found_key;
 281         struct extent_buffer *leaf;
 282         struct btrfs_file_extent_item *extent;
 283         u64 last_offset = 0;
 284         int nritems;
 285         int slot;
 286         int found_type;
 287         int ret;
 288         int err = 0;
 289         u64 extent_end = 0;
 290
 291         path = btrfs_alloc_path();
 292         ret = btrfs_lookup_file_extent(NULL, root, path, inode->i_ino,
 293                                        last_offset, 0);
 294         while (1) {
 295                 nritems = btrfs_header_nritems(path->nodes[0]);
 296                 if (path->slots[0] >= nritems) {
 297                         ret = btrfs_next_leaf(root, path);
 298                         if (ret)
 299                                 goto out;
 300                         nritems = btrfs_header_nritems(path->nodes[0]);
 301                 }
 302                 slot = path->slots[0];
 303                 leaf = path->nodes[0];
 304                 btrfs_item_key_to_cpu(leaf, &found_key, slot);
 305                 if (found_key.objectid != inode->i_ino)
 306                         break;
 307                 if (found_key.type != BTRFS_EXTENT_DATA_KEY)
 308                         goto out;
 309
 310                 if (found_key.offset < last_offset) {
 311                         WARN_ON(1);
 312                         btrfs_print_leaf(root, leaf);
 313                         printk(KERN_ERR "inode %lu found offset %llu "
 314                                "expected %llu\n", inode->i_ino,
 315                                (unsigned long long)found_key.offset,
 316                                (unsigned long long)last_offset);
 317                         err = 1;
 318                         goto out;
 319                 }
 320                 extent = btrfs_item_ptr(leaf, slot,
 321                                         struct btrfs_file_extent_item);
 322                 found_type = btrfs_file_extent_type(leaf, extent);
 323                 if (found_type == BTRFS_FILE_EXTENT_REG) {
 324                         extent_end = found_key.offset +
 325                              btrfs_file_extent_num_bytes(leaf, extent);
 326                 } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
 327                         struct btrfs_item *item;
 328                         item = btrfs_item_nr(leaf, slot);
 329                         extent_end = found_key.offset +
 330                              btrfs_file_extent_inline_len(leaf, extent);
 331                         extent_end = (extent_end + root->sectorsize - 1) &
 332                                 ~((u64)root->sectorsize - 1);
 333                 }
 334                 last_offset = extent_end;
 335                 path->slots[0]++;
 336         }
 337         if (0 && last_offset < inode->i_size) {
 338                 WARN_ON(1);
 339                 btrfs_print_leaf(root, leaf);
 340                 printk(KERN_ERR "inode %lu found offset %llu size %llu\n",
 341                        inode->i_ino, (unsigned long long)last_offset,
 342                        (unsigned long long)inode->i_size);
 343                 err = 1;
 344
 345         }
 346 out:
 347         btrfs_free_path(path);
 348         return err;
 349 #endif
 350 }
 351
 352 /*
 353  * this is very complex, but the basic idea is to drop all extents
 354  * in the range start - end.  hint_block is filled in with a block number
 355  * that would be a good hint to the block allocator for this file.
 356  *
 357  * If an extent intersects the range but is not entirely inside the range
 358  * it is either truncated or split.  Anything entirely inside the range
 359  * is deleted from the tree.
 360  *
 361  * inline_limit is used to tell this code which offsets in the file to keep
 362  * if they contain inline extents.
 363  */
 364 noinline int btrfs_drop_extents(struct btrfs_trans_handle *trans,
 365                        struct btrfs_root *root, struct inode *inode,
 366                        u64 start, u64 end, u64 inline_limit, u64 *hint_byte)
 367 {
 368         u64 extent_end = 0;
 369         u64 locked_end = end;
 370         u64 search_start = start;
 371         u64 leaf_start;
 372         u64 ram_bytes = 0;
 373         u64 orig_parent = 0;
 374         u64 disk_bytenr = 0;
 375         u8 compression;
 376         u8 encryption;
 377         u16 other_encoding = 0;
 378         u64 root_gen;
 379         u64 root_owner;
 380         struct extent_buffer *leaf;
 381         struct btrfs_file_extent_item *extent;
 382         struct btrfs_path *path;
 383         struct btrfs_key key;
 384         struct btrfs_file_extent_item old;
 385         int keep;
 386         int slot;
 387         int bookend;
 388         int found_type = 0;
 389         int found_extent;
 390         int found_inline;
 391         int recow;
 392         int ret;
 393
 394         inline_limit = 0;
 395         btrfs_drop_extent_cache(inode, start, end - 1, 0);
 396
 397         path = btrfs_alloc_path();
 398         if (!path)
 399                 return -ENOMEM;
 400         while (1) {
 401                 recow = 0;
 402                 btrfs_release_path(root, path);
 403                 ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
 404                                                search_start, -1);
 405                 if (ret < 0)
 406                         goto out;
 407                 if (ret > 0) {
 408                         if (path->slots[0] == 0) {
 409                                 ret = 0;
 410                                 goto out;
 411                         }
 412                         path->slots[0]--;
 413                 }
 414 next_slot:
 415                 keep = 0;
 416                 bookend = 0;
 417                 found_extent = 0;
 418                 found_inline = 0;
 419                 leaf_start = 0;
 420                 root_gen = 0;
 421                 root_owner = 0;
 422                 compression = 0;
 423                 encryption = 0;
 424                 extent = NULL;
 425                 leaf = path->nodes[0];
 426                 slot = path->slots[0];
 427                 ret = 0;
 428                 btrfs_item_key_to_cpu(leaf, &key, slot);
 429                 if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY &&
 430                     key.offset >= end) {
 431                         goto out;
 432                 }
 433                 if (btrfs_key_type(&key) > BTRFS_EXTENT_DATA_KEY ||
 434                     key.objectid != inode->i_ino) {
 435                         goto out;
 436                 }
 437                 if (recow) {
 438                         search_start = max(key.offset, start);
 439                         continue;
 440                 }
 441                 if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY) {
 442                         extent = btrfs_item_ptr(leaf, slot,
 443                                                 struct btrfs_file_extent_item);
 444                         found_type = btrfs_file_extent_type(leaf, extent);
 445                         compression = btrfs_file_extent_compression(leaf,
 446                                                                     extent);
 447                         encryption = btrfs_file_extent_encryption(leaf,
 448                                                                   extent);
 449                         other_encoding = btrfs_file_extent_other_encoding(leaf,
 450                                                                   extent);
 451                         if (found_type == BTRFS_FILE_EXTENT_REG ||
 452                             found_type == BTRFS_FILE_EXTENT_PREALLOC) {
 453                                 extent_end =
 454                                      btrfs_file_extent_disk_bytenr(leaf,
 455                                                                    extent);
 456                                 if (extent_end)
 457                                         *hint_byte = extent_end;
 458
 459                                 extent_end = key.offset +
 460                                      btrfs_file_extent_num_bytes(leaf, extent);
 461                                 ram_bytes = btrfs_file_extent_ram_bytes(leaf,
 462                                                                 extent);
 463                                 found_extent = 1;
 464                         } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
 465                                 found_inline = 1;
 466                                 extent_end = key.offset +
 467                                      btrfs_file_extent_inline_len(leaf, extent);
 468                         }
 469                 } else {
 470                         extent_end = search_start;
 471                 }
 472
 473                 /* we found nothing we can drop */
 474                 if ((!found_extent && !found_inline) ||
 475                     search_start >= extent_end) {
 476                         int nextret;
 477                         u32 nritems;
 478                         nritems = btrfs_header_nritems(leaf);
 479                         if (slot >= nritems - 1) {
 480                                 nextret = btrfs_next_leaf(root, path);
 481                                 if (nextret)
 482                                         goto out;
 483                                 recow = 1;
 484                         } else {
 485                                 path->slots[0]++;
 486                         }
 487                         goto next_slot;
 488                 }
 489
 490                 if (end <= extent_end && start >= key.offset && found_inline)
 491                         *hint_byte = EXTENT_MAP_INLINE;
 492
 493                 if (found_extent) {
 494                         read_extent_buffer(leaf, &old, (unsigned long)extent,
 495                                            sizeof(old));
 496                         root_gen = btrfs_header_generation(leaf);
 497                         root_owner = btrfs_header_owner(leaf);
 498                         leaf_start = leaf->start;
 499                 }
 500
 501                 if (end < extent_end && end >= key.offset) {
 502                         bookend = 1;
 503                         if (found_inline && start <= key.offset)
 504                                 keep = 1;
 505                 }
 506
 507                 if (bookend && found_extent) {
 508                         if (locked_end < extent_end) {
 509                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
 510                                                 locked_end, extent_end - 1,
 511                                                 GFP_NOFS);
 512                                 if (!ret) {
 513                                         btrfs_release_path(root, path);
 514                                         lock_extent(&BTRFS_I(inode)->io_tree,
 515                                                 locked_end, extent_end - 1,
 516                                                 GFP_NOFS);
 517                                         locked_end = extent_end;
 518                                         continue;
 519                                 }
 520                                 locked_end = extent_end;
 521                         }
 522                         orig_parent = path->nodes[0]->start;
 523                         disk_bytenr = le64_to_cpu(old.disk_bytenr);
 524                         if (disk_bytenr != 0) {
 525                                 ret = btrfs_inc_extent_ref(trans, root,
 526                                            disk_bytenr,
 527                                            le64_to_cpu(old.disk_num_bytes),
 528                                            orig_parent, root->root_key.objectid,
 529                                            trans->transid, inode->i_ino);
 530                                 BUG_ON(ret);
 531                         }
 532                 }
 533
 534                 if (found_inline) {
 535                         u64 mask = root->sectorsize - 1;
 536                         search_start = (extent_end + mask) & ~mask;
 537                 } else
 538                         search_start = extent_end;
 539
 540                 /* truncate existing extent */
 541                 if (start > key.offset) {
 542                         u64 new_num;
 543                         u64 old_num;
 544                         keep = 1;
 545                         WARN_ON(start & (root->sectorsize - 1));
 546                         if (found_extent) {
 547                                 new_num = start - key.offset;
 548                                 old_num = btrfs_file_extent_num_bytes(leaf,
 549                                                                       extent);
 550                                 *hint_byte =
 551                                         btrfs_file_extent_disk_bytenr(leaf,
 552                                                                       extent);
 553                                 if (btrfs_file_extent_disk_bytenr(leaf,
 554                                                                   extent)) {
 555                                         inode_sub_bytes(inode, old_num -
 556                                                         new_num);
 557                                 }
 558                                 btrfs_set_file_extent_num_bytes(leaf,
 559                                                         extent, new_num);
 560                                 btrfs_mark_buffer_dirty(leaf);
 561                         } else if (key.offset < inline_limit &&
 562                                    (end > extent_end) &&
 563                                    (inline_limit < extent_end)) {
 564                                 u32 new_size;
 565                                 new_size = btrfs_file_extent_calc_inline_size(
 566                                                    inline_limit - key.offset);
 567                                 inode_sub_bytes(inode, extent_end -
 568                                                 inline_limit);
 569                                 btrfs_set_file_extent_ram_bytes(leaf, extent,
 570                                                         new_size);
 571                                 if (!compression && !encryption) {
 572                                         btrfs_truncate_item(trans, root, path,
 573                                                             new_size, 1);
 574                                 }
 575                         }
 576                 }
 577                 /* delete the entire extent */
 578                 if (!keep) {
 579                         if (found_inline)
 580                                 inode_sub_bytes(inode, extent_end -
 581                                                 key.offset);
 582                         ret = btrfs_del_item(trans, root, path);
 583                         /* TODO update progress marker and return */
 584                         BUG_ON(ret);
 585                         extent = NULL;
 586                         btrfs_release_path(root, path);
 587                         /* the extent will be freed later */
 588                 }
 589                 if (bookend && found_inline && start <= key.offset) {
 590                         u32 new_size;
 591                         new_size = btrfs_file_extent_calc_inline_size(
 592                                                    extent_end - end);
 593                         inode_sub_bytes(inode, end - key.offset);
 594                         btrfs_set_file_extent_ram_bytes(leaf, extent,
 595                                                         new_size);
 596                         if (!compression && !encryption)
 597                                 ret = btrfs_truncate_item(trans, root, path,
 598                                                           new_size, 0);
 599                         BUG_ON(ret);
 600                 }
 601                 /* create bookend, splitting the extent in two */
 602                 if (bookend && found_extent) {
 603                         struct btrfs_key ins;
 604                         ins.objectid = inode->i_ino;
 605                         ins.offset = end;
 606                         btrfs_set_key_type(&ins, BTRFS_EXTENT_DATA_KEY);
 607
 608                         btrfs_release_path(root, path);
 609                         ret = btrfs_insert_empty_item(trans, root, path, &ins,
 610                                                       sizeof(*extent));
 611                         BUG_ON(ret);
 612
 613                         leaf = path->nodes[0];
 614                         extent = btrfs_item_ptr(leaf, path->slots[0],
 615                                                 struct btrfs_file_extent_item);
 616                         write_extent_buffer(leaf, &old,
 617                                             (unsigned long)extent, sizeof(old));
 618
 619                         btrfs_set_file_extent_compression(leaf, extent,
 620                                                           compression);
 621                         btrfs_set_file_extent_encryption(leaf, extent,
 622                                                          encryption);
 623                         btrfs_set_file_extent_other_encoding(leaf, extent,
 624                                                              other_encoding);
 625                         btrfs_set_file_extent_offset(leaf, extent,
 626                                     le64_to_cpu(old.offset) + end - key.offset);
 627                         WARN_ON(le64_to_cpu(old.num_bytes) <
 628                                 (extent_end - end));
 629                         btrfs_set_file_extent_num_bytes(leaf, extent,
 630                                                         extent_end - end);
 631
 632                         /*
 633                          * set the ram bytes to the size of the full extent
 634                          * before splitting.  This is a worst case flag,
 635                          * but its the best we can do because we don't know
 636                          * how splitting affects compression
 637                          */
 638                         btrfs_set_file_extent_ram_bytes(leaf, extent,
 639                                                         ram_bytes);
 640                         btrfs_set_file_extent_type(leaf, extent, found_type);
 641
 642                         btrfs_mark_buffer_dirty(path->nodes[0]);
 643
 644                         if (disk_bytenr != 0) {
 645                                 ret = btrfs_update_extent_ref(trans, root,
 646                                                 disk_bytenr, orig_parent,
 647                                                 leaf->start,
 648                                                 root->root_key.objectid,
 649                                                 trans->transid, ins.objectid);
 650
 651                                 BUG_ON(ret);
 652                         }
 653                         btrfs_release_path(root, path);
 654                         if (disk_bytenr != 0)
 655                                 inode_add_bytes(inode, extent_end - end);
 656                 }
 657
 658                 if (found_extent && !keep) {
 659                         u64 old_disk_bytenr = le64_to_cpu(old.disk_bytenr);
 660
 661                         if (old_disk_bytenr != 0) {
 662                                 inode_sub_bytes(inode,
 663                                                 le64_to_cpu(old.num_bytes));
 664                                 ret = btrfs_free_extent(trans, root,
 665                                                 old_disk_bytenr,
 666                                                 le64_to_cpu(old.disk_num_bytes),
 667                                                 leaf_start, root_owner,
 668                                                 root_gen, key.objectid, 0);
 669                                 BUG_ON(ret);
 670                                 *hint_byte = old_disk_bytenr;
 671                         }
 672                 }
 673
 674                 if (search_start >= end) {
 675                         ret = 0;
 676                         goto out;
 677                 }
 678         }
 679 out:
 680         btrfs_free_path(path);
 681         if (locked_end > end) {
 682                 unlock_extent(&BTRFS_I(inode)->io_tree, end, locked_end - 1,
 683                               GFP_NOFS);
 684         }
 685         btrfs_check_file(root, inode);
 686         return ret;
 687 }
 688
 689 static int extent_mergeable(struct extent_buffer *leaf, int slot,
 690                             u64 objectid, u64 bytenr, u64 *start, u64 *end)
 691 {
 692         struct btrfs_file_extent_item *fi;
 693         struct btrfs_key key;
 694         u64 extent_end;
 695
 696         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
 697                 return 0;
 698
 699         btrfs_item_key_to_cpu(leaf, &key, slot);
 700         if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
 701                 return 0;
 702
 703         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
 704         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
 705             btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
 706             btrfs_file_extent_compression(leaf, fi) ||
 707             btrfs_file_extent_encryption(leaf, fi) ||
 708             btrfs_file_extent_other_encoding(leaf, fi))
 709                 return 0;
 710
 711         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 712         if ((*start && *start != key.offset) || (*end && *end != extent_end))
 713                 return 0;
 714
 715         *start = key.offset;
 716         *end = extent_end;
 717         return 1;
 718 }
 719
 720 /*
 721  * Mark extent in the range start - end as written.
 722  *
 723  * This changes extent type from 'pre-allocated' to 'regular'. If only
 724  * part of extent is marked as written, the extent will be split into
 725  * two or three.
 726  */
 727 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
 728                               struct btrfs_root *root,
 729                               struct inode *inode, u64 start, u64 end)
 730 {
 731         struct extent_buffer *leaf;
 732         struct btrfs_path *path;
 733         struct btrfs_file_extent_item *fi;
 734         struct btrfs_key key;
 735         u64 bytenr;
 736         u64 num_bytes;
 737         u64 extent_end;
 738         u64 extent_offset;
 739         u64 other_start;
 740         u64 other_end;
 741         u64 split = start;
 742         u64 locked_end = end;
 743         u64 orig_parent;
 744         int extent_type;
 745         int split_end = 1;
 746         int ret;
 747
 748         btrfs_drop_extent_cache(inode, start, end - 1, 0);
 749
 750         path = btrfs_alloc_path();
 751         BUG_ON(!path);
 752 again:
 753         key.objectid = inode->i_ino;
 754         key.type = BTRFS_EXTENT_DATA_KEY;
 755         if (split == start)
 756                 key.offset = split;
 757         else
 758                 key.offset = split - 1;
 759
 760         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 761         if (ret > 0 && path->slots[0] > 0)
 762                 path->slots[0]--;
 763
 764         leaf = path->nodes[0];
 765         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 766         BUG_ON(key.objectid != inode->i_ino ||
 767                key.type != BTRFS_EXTENT_DATA_KEY);
 768         fi = btrfs_item_ptr(leaf, path->slots[0],
 769                             struct btrfs_file_extent_item);
 770         extent_type = btrfs_file_extent_type(leaf, fi);
 771         BUG_ON(extent_type != BTRFS_FILE_EXTENT_PREALLOC);
 772         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 773         BUG_ON(key.offset > start || extent_end < end);
 774
 775         bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 776         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
 777         extent_offset = btrfs_file_extent_offset(leaf, fi);
 778
 779         if (key.offset == start)
 780                 split = end;
 781
 782         if (key.offset == start && extent_end == end) {
 783                 int del_nr = 0;
 784                 int del_slot = 0;
 785                 u64 leaf_owner = btrfs_header_owner(leaf);
 786                 u64 leaf_gen = btrfs_header_generation(leaf);
 787                 other_start = end;
 788                 other_end = 0;
 789                 if (extent_mergeable(leaf, path->slots[0] + 1, inode->i_ino,
 790                                      bytenr, &other_start, &other_end)) {
 791                         extent_end = other_end;
 792                         del_slot = path->slots[0] + 1;
 793                         del_nr++;
 794                         ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
 795                                                 leaf->start, leaf_owner,
 796                                                 leaf_gen, inode->i_ino, 0);
 797                         BUG_ON(ret);
 798                 }
 799                 other_start = 0;
 800                 other_end = start;
 801                 if (extent_mergeable(leaf, path->slots[0] - 1, inode->i_ino,
 802                                      bytenr, &other_start, &other_end)) {
 803                         key.offset = other_start;
 804                         del_slot = path->slots[0];
 805                         del_nr++;
 806                         ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
 807                                                 leaf->start, leaf_owner,
 808                                                 leaf_gen, inode->i_ino, 0);
 809                         BUG_ON(ret);
 810                 }
 811                 split_end = 0;
 812                 if (del_nr == 0) {
 813                         btrfs_set_file_extent_type(leaf, fi,
 814                                                    BTRFS_FILE_EXTENT_REG);
 815                         goto done;
 816                 }
 817
 818                 fi = btrfs_item_ptr(leaf, del_slot - 1,
 819                                     struct btrfs_file_extent_item);
 820                 btrfs_set_file_extent_type(leaf, fi, BTRFS_FILE_EXTENT_REG);
 821                 btrfs_set_file_extent_num_bytes(leaf, fi,
 822                                                 extent_end - key.offset);
 823                 btrfs_mark_buffer_dirty(leaf);
 824
 825                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
 826                 BUG_ON(ret);
 827                 goto done;
 828         } else if (split == start) {
 829                 if (locked_end < extent_end) {
 830                         ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
 831                                         locked_end, extent_end - 1, GFP_NOFS);
 832                         if (!ret) {
 833                                 btrfs_release_path(root, path);
 834                                 lock_extent(&BTRFS_I(inode)->io_tree,
 835                                         locked_end, extent_end - 1, GFP_NOFS);
 836                                 locked_end = extent_end;
 837                                 goto again;
 838                         }
 839                         locked_end = extent_end;
 840                 }
 841                 btrfs_set_file_extent_num_bytes(leaf, fi, split - key.offset);
 842                 extent_offset += split - key.offset;
 843         } else  {
 844                 BUG_ON(key.offset != start);
 845                 btrfs_set_file_extent_offset(leaf, fi, extent_offset +
 846                                              split - key.offset);
 847                 btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - split);
 848                 key.offset = split;
 849                 btrfs_set_item_key_safe(trans, root, path, &key);
 850                 extent_end = split;
 851         }
 852
 853         if (extent_end == end) {
 854                 split_end = 0;
 855                 extent_type = BTRFS_FILE_EXTENT_REG;
 856         }
 857         if (extent_end == end && split == start) {
 858                 other_start = end;
 859                 other_end = 0;
 860                 if (extent_mergeable(leaf, path->slots[0] + 1, inode->i_ino,
 861                                      bytenr, &other_start, &other_end)) {
 862                         path->slots[0]++;
 863                         fi = btrfs_item_ptr(leaf, path->slots[0],
 864                                             struct btrfs_file_extent_item);
 865                         key.offset = split;
 866                         btrfs_set_item_key_safe(trans, root, path, &key);
 867                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
 868                         btrfs_set_file_extent_num_bytes(leaf, fi,
 869                                                         other_end - split);
 870                         goto done;
 871                 }
 872         }
 873         if (extent_end == end && split == end) {
 874                 other_start = 0;
 875                 other_end = start;
 876                 if (extent_mergeable(leaf, path->slots[0] - 1 , inode->i_ino,
 877                                      bytenr, &other_start, &other_end)) {
 878                         path->slots[0]--;
 879                         fi = btrfs_item_ptr(leaf, path->slots[0],
 880                                             struct btrfs_file_extent_item);
 881                         btrfs_set_file_extent_num_bytes(leaf, fi, extent_end -
 882                                                         other_start);
 883                         goto done;
 884                 }
 885         }
 886
 887         btrfs_mark_buffer_dirty(leaf);
 888
 889         orig_parent = leaf->start;
 890         ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes,
 891                                    orig_parent, root->root_key.objectid,
 892                                    trans->transid, inode->i_ino);
 893         BUG_ON(ret);
 894         btrfs_release_path(root, path);
 895
 896         key.offset = start;
 897         ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*fi));
 898         BUG_ON(ret);
 899
 900         leaf = path->nodes[0];
 901         fi = btrfs_item_ptr(leaf, path->slots[0],
 902                             struct btrfs_file_extent_item);
 903         btrfs_set_file_extent_generation(leaf, fi, trans->transid);
 904         btrfs_set_file_extent_type(leaf, fi, extent_type);
 905         btrfs_set_file_extent_disk_bytenr(leaf, fi, bytenr);
 906         btrfs_set_file_extent_disk_num_bytes(leaf, fi, num_bytes);
 907         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
 908         btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - key.offset);
 909         btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
 910         btrfs_set_file_extent_compression(leaf, fi, 0);
 911         btrfs_set_file_extent_encryption(leaf, fi, 0);
 912         btrfs_set_file_extent_other_encoding(leaf, fi, 0);
 913
 914         if (orig_parent != leaf->start) {
 915                 ret = btrfs_update_extent_ref(trans, root, bytenr,
 916                                               orig_parent, leaf->start,
 917                                               root->root_key.objectid,
 918                                               trans->transid, inode->i_ino);
 919                 BUG_ON(ret);
 920         }
 921 done:
 922         btrfs_mark_buffer_dirty(leaf);
 923         btrfs_release_path(root, path);
 924         if (split_end && split == start) {
 925                 split = end;
 926                 goto again;
 927         }
 928         if (locked_end > end) {
 929                 unlock_extent(&BTRFS_I(inode)->io_tree, end, locked_end - 1,
 930                               GFP_NOFS);
 931         }
 932         btrfs_free_path(path);
 933         return 0;
 934 }
 935
 936 /*
 937  * this gets pages into the page cache and locks them down, it also properly
 938  * waits for data=ordered extents to finish before allowing the pages to be
 939  * modified.
 940  */
 941 static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
 942                          struct page **pages, size_t num_pages,
 943                          loff_t pos, unsigned long first_index,
 944                          unsigned long last_index, size_t write_bytes)
 945 {
 946         int i;
 947         unsigned long index = pos >> PAGE_CACHE_SHIFT;
 948         struct inode *inode = fdentry(file)->d_inode;
 949         int err = 0;
 950         u64 start_pos;
 951         u64 last_pos;
 952
 953         start_pos = pos & ~((u64)root->sectorsize - 1);
 954         last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
 955
 956         if (start_pos > inode->i_size) {
 957                 err = btrfs_cont_expand(inode, start_pos);
 958                 if (err)
 959                         return err;
 960         }
 961
 962         memset(pages, 0, num_pages * sizeof(struct page *));
 963 again:
 964         for (i = 0; i < num_pages; i++) {
 965                 pages[i] = grab_cache_page(inode->i_mapping, index + i);
 966                 if (!pages[i]) {
 967                         err = -ENOMEM;
 968                         BUG_ON(1);
 969                 }
 970                 wait_on_page_writeback(pages[i]);
 971         }
 972         if (start_pos < inode->i_size) {
 973                 struct btrfs_ordered_extent *ordered;
 974                 lock_extent(&BTRFS_I(inode)->io_tree,
 975                             start_pos, last_pos - 1, GFP_NOFS);
 976                 ordered = btrfs_lookup_first_ordered_extent(inode,
 977                                                             last_pos - 1);
 978                 if (ordered &&
 979                     ordered->file_offset + ordered->len > start_pos &&
 980                     ordered->file_offset < last_pos) {
 981                         btrfs_put_ordered_extent(ordered);
 982                         unlock_extent(&BTRFS_I(inode)->io_tree,
 983                                       start_pos, last_pos - 1, GFP_NOFS);
 984                         for (i = 0; i < num_pages; i++) {
 985                                 unlock_page(pages[i]);
 986                                 page_cache_release(pages[i]);
 987                         }
 988                         btrfs_wait_ordered_range(inode, start_pos,
 989                                                  last_pos - start_pos);
 990                         goto again;
 991                 }
 992                 if (ordered)
 993                         btrfs_put_ordered_extent(ordered);
 994
 995                 clear_extent_bits(&BTRFS_I(inode)->io_tree, start_pos,
 996                                   last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC,
 997                                   GFP_NOFS);
 998                 unlock_extent(&BTRFS_I(inode)->io_tree,
 999                               start_pos, last_pos - 1, GFP_NOFS);
1000         }
1001         for (i = 0; i < num_pages; i++) {
1002                 clear_page_dirty_for_io(pages[i]);
1003                 set_page_extent_mapped(pages[i]);
1004                 WARN_ON(!PageLocked(pages[i]));
1005         }
1006         return 0;
1007 }
1008
1009 static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
1010                                 size_t count, loff_t *ppos)
1011 {
1012         loff_t pos;
1013         loff_t start_pos;
1014         ssize_t num_written = 0;
1015         ssize_t err = 0;
1016         int ret = 0;
1017         struct inode *inode = fdentry(file)->d_inode;
1018         struct btrfs_root *root = BTRFS_I(inode)->root;
1019         struct page **pages = NULL;
1020         int nrptrs;
1021         struct page *pinned[2];
1022         unsigned long first_index;
1023         unsigned long last_index;
1024         int will_write;
1025
1026         will_write = ((file->f_flags & O_SYNC) || IS_SYNC(inode) ||
1027                       (file->f_flags & O_DIRECT));
1028
1029         nrptrs = min((count + PAGE_CACHE_SIZE - 1) / PAGE_CACHE_SIZE,
1030                      PAGE_CACHE_SIZE / (sizeof(struct page *)));
1031         pinned[0] = NULL;
1032         pinned[1] = NULL;
1033
1034         pos = *ppos;
1035         start_pos = pos;
1036
1037         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
1038         current->backing_dev_info = inode->i_mapping->backing_dev_info;
1039         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
1040         if (err)
1041                 goto out_nolock;
1042         if (count == 0)
1043                 goto out_nolock;
1044
1045         err = file_remove_suid(file);
1046         if (err)
1047                 goto out_nolock;
1048         file_update_time(file);
1049
1050         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
1051
1052         mutex_lock(&inode->i_mutex);
1053         BTRFS_I(inode)->sequence++;
1054         first_index = pos >> PAGE_CACHE_SHIFT;
1055         last_index = (pos + count) >> PAGE_CACHE_SHIFT;
1056
1057         /*
1058          * there are lots of better ways to do this, but this code
1059          * makes sure the first and last page in the file range are
1060          * up to date and ready for cow
1061          */
1062         if ((pos & (PAGE_CACHE_SIZE - 1))) {
1063                 pinned[0] = grab_cache_page(inode->i_mapping, first_index);
1064                 if (!PageUptodate(pinned[0])) {
1065                         ret = btrfs_readpage(NULL, pinned[0]);
1066                         BUG_ON(ret);
1067                         wait_on_page_locked(pinned[0]);
1068                 } else {
1069                         unlock_page(pinned[0]);
1070                 }
1071         }
1072         if ((pos + count) & (PAGE_CACHE_SIZE - 1)) {
1073                 pinned[1] = grab_cache_page(inode->i_mapping, last_index);
1074                 if (!PageUptodate(pinned[1])) {
1075                         ret = btrfs_readpage(NULL, pinned[1]);
1076                         BUG_ON(ret);
1077                         wait_on_page_locked(pinned[1]);
1078                 } else {
1079                         unlock_page(pinned[1]);
1080                 }
1081         }
1082
1083         while (count > 0) {
1084                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
1085                 size_t write_bytes = min(count, nrptrs *
1086                                         (size_t)PAGE_CACHE_SIZE -
1087                                          offset);
1088                 size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
1089                                         PAGE_CACHE_SHIFT;
1090
1091                 WARN_ON(num_pages > nrptrs);
1092                 memset(pages, 0, sizeof(struct page *) * nrptrs);
1093
1094                 ret = btrfs_check_data_free_space(root, inode, write_bytes);
1095                 if (ret)
1096                         goto out;
1097
1098                 ret = prepare_pages(root, file, pages, num_pages,
1099                                     pos, first_index, last_index,
1100                                     write_bytes);
1101                 if (ret) {
1102                         btrfs_free_reserved_data_space(root, inode,
1103                                                        write_bytes);
1104                         goto out;
1105                 }
1106
1107                 ret = btrfs_copy_from_user(pos, num_pages,
1108                                            write_bytes, pages, buf);
1109                 if (ret) {
1110                         btrfs_free_reserved_data_space(root, inode,
1111                                                        write_bytes);
1112                         btrfs_drop_pages(pages, num_pages);
1113                         goto out;
1114                 }
1115
1116                 ret = dirty_and_release_pages(NULL, root, file, pages,
1117                                               num_pages, pos, write_bytes);
1118                 btrfs_drop_pages(pages, num_pages);
1119                 if (ret) {
1120                         btrfs_free_reserved_data_space(root, inode,
1121                                                        write_bytes);
1122                         goto out;
1123                 }
1124
1125                 if (will_write) {
1126                         btrfs_fdatawrite_range(inode->i_mapping, pos,
1127                                                pos + write_bytes - 1,
1128                                                WB_SYNC_NONE);
1129                 } else {
1130                         balance_dirty_pages_ratelimited_nr(inode->i_mapping,
1131                                                            num_pages);
1132                         if (num_pages <
1133                             (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
1134                                 btrfs_btree_balance_dirty(root, 1);
1135                         btrfs_throttle(root);
1136                 }
1137
1138                 buf += write_bytes;
1139                 count -= write_bytes;
1140                 pos += write_bytes;
1141                 num_written += write_bytes;
1142
1143                 cond_resched();
1144         }
1145 out:
1146         mutex_unlock(&inode->i_mutex);
1147         if (ret)
1148                 err = ret;
1149
1150 out_nolock:
1151         kfree(pages);
1152         if (pinned[0])
1153                 page_cache_release(pinned[0]);
1154         if (pinned[1])
1155                 page_cache_release(pinned[1]);
1156         *ppos = pos;
1157
1158         if (num_written > 0 && will_write) {
1159                 struct btrfs_trans_handle *trans;
1160
1161                 err = btrfs_wait_ordered_range(inode, start_pos, num_written);
1162                 if (err)
1163                         num_written = err;
1164
1165                 if ((file->f_flags & O_SYNC) || IS_SYNC(inode)) {
1166                         trans = btrfs_start_transaction(root, 1);
1167                         ret = btrfs_log_dentry_safe(trans, root,
1168                                                     file->f_dentry);
1169                         if (ret == 0) {
1170                                 btrfs_sync_log(trans, root);
1171                                 btrfs_end_transaction(trans, root);
1172                         } else {
1173                                 btrfs_commit_transaction(trans, root);
1174                         }
1175                 }
1176                 if (file->f_flags & O_DIRECT) {
1177                         invalidate_mapping_pages(inode->i_mapping,
1178                               start_pos >> PAGE_CACHE_SHIFT,
1179                              (start_pos + num_written - 1) >> PAGE_CACHE_SHIFT);
1180                 }
1181         }
1182         current->backing_dev_info = NULL;
1183         return num_written ? num_written : err;
1184 }
1185
1186 int btrfs_release_file(struct inode *inode, struct file *filp)
1187 {
1188         if (filp->private_data)
1189                 btrfs_ioctl_trans_end(filp);
1190         return 0;
1191 }
1192
1193 /*
1194  * fsync call for both files and directories.  This logs the inode into
1195  * the tree log instead of forcing full commits whenever possible.
1196  *
1197  * It needs to call filemap_fdatawait so that all ordered extent updates are
1198  * in the metadata btree are up to date for copying to the log.
1199  *
1200  * It drops the inode mutex before doing the tree log commit.  This is an
1201  * important optimization for directories because holding the mutex prevents
1202  * new operations on the dir while we write to disk.
1203  */
1204 int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
1205 {
1206         struct inode *inode = dentry->d_inode;
1207         struct btrfs_root *root = BTRFS_I(inode)->root;
1208         int ret = 0;
1209         struct btrfs_trans_handle *trans;
1210
1211         /*
1212          * check the transaction that last modified this inode
1213          * and see if its already been committed
1214          */
1215         if (!BTRFS_I(inode)->last_trans)
1216                 goto out;
1217
1218         mutex_lock(&root->fs_info->trans_mutex);
1219         if (BTRFS_I(inode)->last_trans <=
1220             root->fs_info->last_trans_committed) {
1221                 BTRFS_I(inode)->last_trans = 0;
1222                 mutex_unlock(&root->fs_info->trans_mutex);
1223                 goto out;
1224         }
1225         mutex_unlock(&root->fs_info->trans_mutex);
1226
1227         root->log_batch++;
1228         filemap_fdatawrite(inode->i_mapping);
1229         btrfs_wait_ordered_range(inode, 0, (u64)-1);
1230         root->log_batch++;
1231
1232         /*
1233          * ok we haven't committed the transaction yet, lets do a commit
1234          */
1235         if (file && file->private_data)
1236                 btrfs_ioctl_trans_end(file);
1237
1238         trans = btrfs_start_transaction(root, 1);
1239         if (!trans) {
1240                 ret = -ENOMEM;
1241                 goto out;
1242         }
1243
1244         ret = btrfs_log_dentry_safe(trans, root, dentry);
1245         if (ret < 0)
1246                 goto out;
1247
1248         /* we've logged all the items and now have a consistent
1249          * version of the file in the log.  It is possible that
1250          * someone will come in and modify the file, but that's
1251          * fine because the log is consistent on disk, and we
1252          * have references to all of the file's extents
1253          *
1254          * It is possible that someone will come in and log the
1255          * file again, but that will end up using the synchronization
1256          * inside btrfs_sync_log to keep things safe.
1257          */
1258         mutex_unlock(&dentry->d_inode->i_mutex);
1259
1260         if (ret > 0) {
1261                 ret = btrfs_commit_transaction(trans, root);
1262         } else {
1263                 btrfs_sync_log(trans, root);
1264                 ret = btrfs_end_transaction(trans, root);
1265         }
1266         mutex_lock(&dentry->d_inode->i_mutex);
1267 out:
1268         return ret > 0 ? EIO : ret;
1269 }
1270
1271 static struct vm_operations_struct btrfs_file_vm_ops = {
1272         .fault          = filemap_fault,
1273         .page_mkwrite   = btrfs_page_mkwrite,
1274 };
1275
1276 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
1277 {
1278         vma->vm_ops = &btrfs_file_vm_ops;
1279         file_accessed(filp);
1280         return 0;
1281 }
1282
1283 struct file_operations btrfs_file_operations = {
1284         .llseek         = generic_file_llseek,
1285         .read           = do_sync_read,
1286         .aio_read       = generic_file_aio_read,
1287         .splice_read    = generic_file_splice_read,
1288         .write          = btrfs_file_write,
1289         .mmap           = btrfs_file_mmap,
1290         .open           = generic_file_open,
1291         .release        = btrfs_release_file,
1292         .fsync          = btrfs_sync_file,
1293         .unlocked_ioctl = btrfs_ioctl,
1294 #ifdef CONFIG_COMPAT
1295         .compat_ioctl   = btrfs_ioctl,
1296 #endif
1297 };