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   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 <linux/version.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 int noinline btrfs_copy_from_user(loff_t pos, int num_pages,
  48                                          int write_bytes,
  49                                          struct page **prepared_pages,
  50                                          const char __user * buf)
  51 {
  52         long page_fault = 0;
  53         int i;
  54         int offset = pos & (PAGE_CACHE_SIZE - 1);
  55
  56         for (i = 0; i < num_pages && write_bytes > 0; i++, offset = 0) {
  57                 size_t count = min_t(size_t,
  58                                      PAGE_CACHE_SIZE - offset, write_bytes);
  59                 struct page *page = prepared_pages[i];
  60                 fault_in_pages_readable(buf, count);
  61
  62                 /* Copy data from userspace to the current page */
  63                 kmap(page);
  64                 page_fault = __copy_from_user(page_address(page) + offset,
  65                                               buf, count);
  66                 /* Flush processor's dcache for this page */
  67                 flush_dcache_page(page);
  68                 kunmap(page);
  69                 buf += count;
  70                 write_bytes -= count;
  71
  72                 if (page_fault)
  73                         break;
  74         }
  75         return page_fault ? -EFAULT : 0;
  76 }
  77
  78 /*
  79  * unlocks pages after btrfs_file_write is done with them
  80  */
  81 static void noinline btrfs_drop_pages(struct page **pages, size_t num_pages)
  82 {
  83         size_t i;
  84         for (i = 0; i < num_pages; i++) {
  85                 if (!pages[i])
  86                         break;
  87                 /* page checked is some magic around finding pages that
  88                  * have been modified without going through btrfs_set_page_dirty
  89                  * clear it here
  90                  */
  91                 ClearPageChecked(pages[i]);
  92                 unlock_page(pages[i]);
  93                 mark_page_accessed(pages[i]);
  94                 page_cache_release(pages[i]);
  95         }
  96 }
  97
  98 /*
  99  * after copy_from_user, pages need to be dirtied and we need to make
 100  * sure holes are created between the current EOF and the start of
 101  * any next extents (if required).
 102  *
 103  * this also makes the decision about creating an inline extent vs
 104  * doing real data extents, marking pages dirty and delalloc as required.
 105  */
 106 static int noinline dirty_and_release_pages(struct btrfs_trans_handle *trans,
 107                                    struct btrfs_root *root,
 108                                    struct file *file,
 109                                    struct page **pages,
 110                                    size_t num_pages,
 111                                    loff_t pos,
 112                                    size_t write_bytes)
 113 {
 114         int err = 0;
 115         int i;
 116         struct inode *inode = fdentry(file)->d_inode;
 117         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 118         u64 hint_byte;
 119         u64 num_bytes;
 120         u64 start_pos;
 121         u64 end_of_last_block;
 122         u64 end_pos = pos + write_bytes;
 123         loff_t isize = i_size_read(inode);
 124
 125         start_pos = pos & ~((u64)root->sectorsize - 1);
 126         num_bytes = (write_bytes + pos - start_pos +
 127                     root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
 128
 129         end_of_last_block = start_pos + num_bytes - 1;
 130
 131         lock_extent(io_tree, start_pos, end_of_last_block, GFP_NOFS);
 132         trans = btrfs_join_transaction(root, 1);
 133         if (!trans) {
 134                 err = -ENOMEM;
 135                 goto out_unlock;
 136         }
 137         btrfs_set_trans_block_group(trans, inode);
 138         hint_byte = 0;
 139
 140         if ((end_of_last_block & 4095) == 0) {
 141                 printk("strange end of last %Lu %zu %Lu\n", start_pos, write_bytes, end_of_last_block);
 142         }
 143         set_extent_uptodate(io_tree, start_pos, end_of_last_block, GFP_NOFS);
 144
 145         /* check for reserved extents on each page, we don't want
 146          * to reset the delalloc bit on things that already have
 147          * extents reserved.
 148          */
 149         btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block);
 150         for (i = 0; i < num_pages; i++) {
 151                 struct page *p = pages[i];
 152                 SetPageUptodate(p);
 153                 ClearPageChecked(p);
 154                 set_page_dirty(p);
 155         }
 156         if (end_pos > isize) {
 157                 i_size_write(inode, end_pos);
 158                 btrfs_update_inode(trans, root, inode);
 159         }
 160         err = btrfs_end_transaction(trans, root);
 161 out_unlock:
 162         unlock_extent(io_tree, start_pos, end_of_last_block, GFP_NOFS);
 163         return err;
 164 }
 165
 166 /*
 167  * this drops all the extents in the cache that intersect the range
 168  * [start, end].  Existing extents are split as required.
 169  */
 170 int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
 171                             int skip_pinned)
 172 {
 173         struct extent_map *em;
 174         struct extent_map *split = NULL;
 175         struct extent_map *split2 = NULL;
 176         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
 177         u64 len = end - start + 1;
 178         int ret;
 179         int testend = 1;
 180         unsigned long flags;
 181         int compressed = 0;
 182
 183         WARN_ON(end < start);
 184         if (end == (u64)-1) {
 185                 len = (u64)-1;
 186                 testend = 0;
 187         }
 188         while(1) {
 189                 if (!split)
 190                         split = alloc_extent_map(GFP_NOFS);
 191                 if (!split2)
 192                         split2 = alloc_extent_map(GFP_NOFS);
 193
 194                 spin_lock(&em_tree->lock);
 195                 em = lookup_extent_mapping(em_tree, start, len);
 196                 if (!em) {
 197                         spin_unlock(&em_tree->lock);
 198                         break;
 199                 }
 200                 flags = em->flags;
 201                 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
 202                         spin_unlock(&em_tree->lock);
 203                         if (em->start <= start &&
 204                             (!testend || em->start + em->len >= start + len)) {
 205                                 free_extent_map(em);
 206                                 break;
 207                         }
 208                         if (start < em->start) {
 209                                 len = em->start - start;
 210                         } else {
 211                                 len = start + len - (em->start + em->len);
 212                                 start = em->start + em->len;
 213                         }
 214                         free_extent_map(em);
 215                         continue;
 216                 }
 217                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 218                 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
 219                 remove_extent_mapping(em_tree, em);
 220
 221                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 222                     em->start < start) {
 223                         split->start = em->start;
 224                         split->len = start - em->start;
 225                         split->orig_start = em->orig_start;
 226                         split->block_start = em->block_start;
 227
 228                         if (compressed)
 229                                 split->block_len = em->block_len;
 230                         else
 231                                 split->block_len = split->len;
 232
 233                         split->bdev = em->bdev;
 234                         split->flags = flags;
 235                         ret = add_extent_mapping(em_tree, split);
 236                         BUG_ON(ret);
 237                         free_extent_map(split);
 238                         split = split2;
 239                         split2 = NULL;
 240                 }
 241                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 242                     testend && em->start + em->len > start + len) {
 243                         u64 diff = start + len - em->start;
 244
 245                         split->start = start + len;
 246                         split->len = em->start + em->len - (start + len);
 247                         split->bdev = em->bdev;
 248                         split->flags = flags;
 249
 250                         if (compressed) {
 251                                 split->block_len = em->block_len;
 252                                 split->block_start = em->block_start;
 253                                 split->orig_start = em->orig_start;
 254                         } else {
 255                                 split->block_len = split->len;
 256                                 split->block_start = em->block_start + diff;
 257                                 split->orig_start = split->start;
 258                         }
 259
 260                         ret = add_extent_mapping(em_tree, split);
 261                         BUG_ON(ret);
 262                         free_extent_map(split);
 263                         split = NULL;
 264                 }
 265                 spin_unlock(&em_tree->lock);
 266
 267                 /* once for us */
 268                 free_extent_map(em);
 269                 /* once for the tree*/
 270                 free_extent_map(em);
 271         }
 272         if (split)
 273                 free_extent_map(split);
 274         if (split2)
 275                 free_extent_map(split2);
 276         return 0;
 277 }
 278
 279 int btrfs_check_file(struct btrfs_root *root, struct inode *inode)
 280 {
 281         return 0;
 282 #if 0
 283         struct btrfs_path *path;
 284         struct btrfs_key found_key;
 285         struct extent_buffer *leaf;
 286         struct btrfs_file_extent_item *extent;
 287         u64 last_offset = 0;
 288         int nritems;
 289         int slot;
 290         int found_type;
 291         int ret;
 292         int err = 0;
 293         u64 extent_end = 0;
 294
 295         path = btrfs_alloc_path();
 296         ret = btrfs_lookup_file_extent(NULL, root, path, inode->i_ino,
 297                                        last_offset, 0);
 298         while(1) {
 299                 nritems = btrfs_header_nritems(path->nodes[0]);
 300                 if (path->slots[0] >= nritems) {
 301                         ret = btrfs_next_leaf(root, path);
 302                         if (ret)
 303                                 goto out;
 304                         nritems = btrfs_header_nritems(path->nodes[0]);
 305                 }
 306                 slot = path->slots[0];
 307                 leaf = path->nodes[0];
 308                 btrfs_item_key_to_cpu(leaf, &found_key, slot);
 309                 if (found_key.objectid != inode->i_ino)
 310                         break;
 311                 if (found_key.type != BTRFS_EXTENT_DATA_KEY)
 312                         goto out;
 313
 314                 if (found_key.offset < last_offset) {
 315                         WARN_ON(1);
 316                         btrfs_print_leaf(root, leaf);
 317                         printk("inode %lu found offset %Lu expected %Lu\n",
 318                                inode->i_ino, found_key.offset, last_offset);
 319                         err = 1;
 320                         goto out;
 321                 }
 322                 extent = btrfs_item_ptr(leaf, slot,
 323                                         struct btrfs_file_extent_item);
 324                 found_type = btrfs_file_extent_type(leaf, extent);
 325                 if (found_type == BTRFS_FILE_EXTENT_REG) {
 326                         extent_end = found_key.offset +
 327                              btrfs_file_extent_num_bytes(leaf, extent);
 328                 } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
 329                         struct btrfs_item *item;
 330                         item = btrfs_item_nr(leaf, slot);
 331                         extent_end = found_key.offset +
 332                              btrfs_file_extent_inline_len(leaf, extent);
 333                         extent_end = (extent_end + root->sectorsize - 1) &
 334                                 ~((u64)root->sectorsize -1 );
 335                 }
 336                 last_offset = extent_end;
 337                 path->slots[0]++;
 338         }
 339         if (0 && last_offset < inode->i_size) {
 340                 WARN_ON(1);
 341                 btrfs_print_leaf(root, leaf);
 342                 printk("inode %lu found offset %Lu size %Lu\n", inode->i_ino,
 343                        last_offset, inode->i_size);
 344                 err = 1;
 345
 346         }
 347 out:
 348         btrfs_free_path(path);
 349         return err;
 350 #endif
 351 }
 352
 353 /*
 354  * this is very complex, but the basic idea is to drop all extents
 355  * in the range start - end.  hint_block is filled in with a block number
 356  * that would be a good hint to the block allocator for this file.
 357  *
 358  * If an extent intersects the range but is not entirely inside the range
 359  * it is either truncated or split.  Anything entirely inside the range
 360  * is deleted from the tree.
 361  *
 362  * inline_limit is used to tell this code which offsets in the file to keep
 363  * if they contain inline extents.
 364  */
 365 int noinline btrfs_drop_extents(struct btrfs_trans_handle *trans,
 366                        struct btrfs_root *root, struct inode *inode,
 367                        u64 start, u64 end, u64 inline_limit, u64 *hint_byte)
 368 {
 369         u64 extent_end = 0;
 370         u64 locked_end = end;
 371         u64 search_start = start;
 372         u64 leaf_start;
 373         u64 ram_bytes = 0;
 374         u64 orig_parent = 0;
 375         u64 disk_bytenr = 0;
 376         u8 compression;
 377         u8 encryption;
 378         u16 other_encoding = 0;
 379         u64 root_gen;
 380         u64 root_owner;
 381         struct extent_buffer *leaf;
 382         struct btrfs_file_extent_item *extent;
 383         struct btrfs_path *path;
 384         struct btrfs_key key;
 385         struct btrfs_file_extent_item old;
 386         int keep;
 387         int slot;
 388         int bookend;
 389         int found_type = 0;
 390         int found_extent;
 391         int found_inline;
 392         int recow;
 393         int ret;
 394
 395         inline_limit = 0;
 396         btrfs_drop_extent_cache(inode, start, end - 1, 0);
 397
 398         path = btrfs_alloc_path();
 399         if (!path)
 400                 return -ENOMEM;
 401         while(1) {
 402                 recow = 0;
 403                 btrfs_release_path(root, path);
 404                 ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
 405                                                search_start, -1);
 406                 if (ret < 0)
 407                         goto out;
 408                 if (ret > 0) {
 409                         if (path->slots[0] == 0) {
 410                                 ret = 0;
 411                                 goto out;
 412                         }
 413                         path->slots[0]--;
 414                 }
 415 next_slot:
 416                 keep = 0;
 417                 bookend = 0;
 418                 found_extent = 0;
 419                 found_inline = 0;
 420                 leaf_start = 0;
 421                 root_gen = 0;
 422                 root_owner = 0;
 423                 compression = 0;
 424                 encryption = 0;
 425                 extent = NULL;
 426                 leaf = path->nodes[0];
 427                 slot = path->slots[0];
 428                 ret = 0;
 429                 btrfs_item_key_to_cpu(leaf, &key, slot);
 430                 if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY &&
 431                     key.offset >= end) {
 432                         goto out;
 433                 }
 434                 if (btrfs_key_type(&key) > BTRFS_EXTENT_DATA_KEY ||
 435                     key.objectid != inode->i_ino) {
 436                         goto out;
 437                 }
 438                 if (recow) {
 439                         search_start = max(key.offset, start);
 440                         continue;
 441                 }
 442                 if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY) {
 443                         extent = btrfs_item_ptr(leaf, slot,
 444                                                 struct btrfs_file_extent_item);
 445                         found_type = btrfs_file_extent_type(leaf, extent);
 446                         compression = btrfs_file_extent_compression(leaf,
 447                                                                     extent);
 448                         encryption = btrfs_file_extent_encryption(leaf,
 449                                                                   extent);
 450                         other_encoding = btrfs_file_extent_other_encoding(leaf,
 451                                                                   extent);
 452                         if (found_type == BTRFS_FILE_EXTENT_REG ||
 453                             found_type == BTRFS_FILE_EXTENT_PREALLOC) {
 454                                 extent_end =
 455                                      btrfs_file_extent_disk_bytenr(leaf,
 456                                                                    extent);
 457                                 if (extent_end)
 458                                         *hint_byte = extent_end;
 459
 460                                 extent_end = key.offset +
 461                                      btrfs_file_extent_num_bytes(leaf, extent);
 462                                 ram_bytes = btrfs_file_extent_ram_bytes(leaf,
 463                                                                 extent);
 464                                 found_extent = 1;
 465                         } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
 466                                 found_inline = 1;
 467                                 extent_end = key.offset +
 468                                      btrfs_file_extent_inline_len(leaf, extent);
 469                         }
 470                 } else {
 471                         extent_end = search_start;
 472                 }
 473
 474                 /* we found nothing we can drop */
 475                 if ((!found_extent && !found_inline) ||
 476                     search_start >= extent_end) {
 477                         int nextret;
 478                         u32 nritems;
 479                         nritems = btrfs_header_nritems(leaf);
 480                         if (slot >= nritems - 1) {
 481                                 nextret = btrfs_next_leaf(root, path);
 482                                 if (nextret)
 483                                         goto out;
 484                                 recow = 1;
 485                         } else {
 486                                 path->slots[0]++;
 487                         }
 488                         goto next_slot;
 489                 }
 490
 491                 if (end <= extent_end && start >= key.offset && found_inline)
 492                         *hint_byte = EXTENT_MAP_INLINE;
 493
 494                 if (found_extent) {
 495                         read_extent_buffer(leaf, &old, (unsigned long)extent,
 496                                            sizeof(old));
 497                         root_gen = btrfs_header_generation(leaf);
 498                         root_owner = btrfs_header_owner(leaf);
 499                         leaf_start = leaf->start;
 500                 }
 501
 502                 if (end < extent_end && end >= key.offset) {
 503                         bookend = 1;
 504                         if (found_inline && start <= key.offset)
 505                                 keep = 1;
 506                 }
 507
 508                 if (bookend && found_extent) {
 509                         if (locked_end < extent_end) {
 510                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
 511                                                 locked_end, extent_end - 1,
 512                                                 GFP_NOFS);
 513                                 if (!ret) {
 514                                         btrfs_release_path(root, path);
 515                                         lock_extent(&BTRFS_I(inode)->io_tree,
 516                                                 locked_end, extent_end - 1,
 517                                                 GFP_NOFS);
 518                                         locked_end = extent_end;
 519                                         continue;
 520                                 }
 521                                 locked_end = extent_end;
 522                         }
 523                         orig_parent = path->nodes[0]->start;
 524                         disk_bytenr = le64_to_cpu(old.disk_bytenr);
 525                         if (disk_bytenr != 0) {
 526                                 ret = btrfs_inc_extent_ref(trans, root,
 527                                            disk_bytenr,
 528                                            le64_to_cpu(old.disk_num_bytes),
 529                                            orig_parent, root->root_key.objectid,
 530                                            trans->transid, inode->i_ino);
 531                                 BUG_ON(ret);
 532                         }
 533                 }
 534
 535                 if (found_inline) {
 536                         u64 mask = root->sectorsize - 1;
 537                         search_start = (extent_end + mask) & ~mask;
 538                 } else
 539                         search_start = extent_end;
 540
 541                 /* truncate existing extent */
 542                 if (start > key.offset) {
 543                         u64 new_num;
 544                         u64 old_num;
 545                         keep = 1;
 546                         WARN_ON(start & (root->sectorsize - 1));
 547                         if (found_extent) {
 548                                 new_num = start - key.offset;
 549                                 old_num = btrfs_file_extent_num_bytes(leaf,
 550                                                                       extent);
 551                                 *hint_byte =
 552                                         btrfs_file_extent_disk_bytenr(leaf,
 553                                                                       extent);
 554                                 if (btrfs_file_extent_disk_bytenr(leaf,
 555                                                                   extent)) {
 556                                         inode_sub_bytes(inode, old_num -
 557                                                         new_num);
 558                                 }
 559                                 if (!compression && !encryption) {
 560                                         btrfs_set_file_extent_ram_bytes(leaf,
 561                                                         extent, new_num);
 562                                 }
 563                                 btrfs_set_file_extent_num_bytes(leaf,
 564                                                         extent, new_num);
 565                                 btrfs_mark_buffer_dirty(leaf);
 566                         } else if (key.offset < inline_limit &&
 567                                    (end > extent_end) &&
 568                                    (inline_limit < extent_end)) {
 569                                 u32 new_size;
 570                                 new_size = btrfs_file_extent_calc_inline_size(
 571                                                    inline_limit - key.offset);
 572                                 inode_sub_bytes(inode, extent_end -
 573                                                 inline_limit);
 574                                 btrfs_set_file_extent_ram_bytes(leaf, extent,
 575                                                         new_size);
 576                                 if (!compression && !encryption) {
 577                                         btrfs_truncate_item(trans, root, path,
 578                                                             new_size, 1);
 579                                 }
 580                         }
 581                 }
 582                 /* delete the entire extent */
 583                 if (!keep) {
 584                         if (found_inline)
 585                                 inode_sub_bytes(inode, extent_end -
 586                                                 key.offset);
 587                         ret = btrfs_del_item(trans, root, path);
 588                         /* TODO update progress marker and return */
 589                         BUG_ON(ret);
 590                         extent = NULL;
 591                         btrfs_release_path(root, path);
 592                         /* the extent will be freed later */
 593                 }
 594                 if (bookend && found_inline && start <= key.offset) {
 595                         u32 new_size;
 596                         new_size = btrfs_file_extent_calc_inline_size(
 597                                                    extent_end - end);
 598                         inode_sub_bytes(inode, end - key.offset);
 599                         btrfs_set_file_extent_ram_bytes(leaf, extent,
 600                                                         new_size);
 601                         if (!compression && !encryption)
 602                                 ret = btrfs_truncate_item(trans, root, path,
 603                                                           new_size, 0);
 604                         BUG_ON(ret);
 605                 }
 606                 /* create bookend, splitting the extent in two */
 607                 if (bookend && found_extent) {
 608                         struct btrfs_key ins;
 609                         ins.objectid = inode->i_ino;
 610                         ins.offset = end;
 611                         btrfs_set_key_type(&ins, BTRFS_EXTENT_DATA_KEY);
 612
 613                         btrfs_release_path(root, path);
 614                         ret = btrfs_insert_empty_item(trans, root, path, &ins,
 615                                                       sizeof(*extent));
 616                         BUG_ON(ret);
 617
 618                         leaf = path->nodes[0];
 619                         extent = btrfs_item_ptr(leaf, path->slots[0],
 620                                                 struct btrfs_file_extent_item);
 621                         write_extent_buffer(leaf, &old,
 622                                             (unsigned long)extent, sizeof(old));
 623
 624                         btrfs_set_file_extent_compression(leaf, extent,
 625                                                           compression);
 626                         btrfs_set_file_extent_encryption(leaf, extent,
 627                                                          encryption);
 628                         btrfs_set_file_extent_other_encoding(leaf, extent,
 629                                                              other_encoding);
 630                         btrfs_set_file_extent_offset(leaf, extent,
 631                                     le64_to_cpu(old.offset) + end - key.offset);
 632                         WARN_ON(le64_to_cpu(old.num_bytes) <
 633                                 (extent_end - end));
 634                         btrfs_set_file_extent_num_bytes(leaf, extent,
 635                                                         extent_end - end);
 636
 637                         /*
 638                          * set the ram bytes to the size of the full extent
 639                          * before splitting.  This is a worst case flag,
 640                          * but its the best we can do because we don't know
 641                          * how splitting affects compression
 642                          */
 643                         btrfs_set_file_extent_ram_bytes(leaf, extent,
 644                                                         ram_bytes);
 645                         btrfs_set_file_extent_type(leaf, extent, found_type);
 646
 647                         btrfs_mark_buffer_dirty(path->nodes[0]);
 648
 649                         if (disk_bytenr != 0) {
 650                                 ret = btrfs_update_extent_ref(trans, root,
 651                                                 disk_bytenr, orig_parent,
 652                                                 leaf->start,
 653                                                 root->root_key.objectid,
 654                                                 trans->transid, ins.objectid);
 655
 656                                 BUG_ON(ret);
 657                         }
 658                         btrfs_release_path(root, path);
 659                         if (disk_bytenr != 0) {
 660                                 inode_add_bytes(inode, extent_end - end);
 661                         }
 662                 }
 663
 664                 if (found_extent && !keep) {
 665                         u64 disk_bytenr = le64_to_cpu(old.disk_bytenr);
 666
 667                         if (disk_bytenr != 0) {
 668                                 inode_sub_bytes(inode,
 669                                                 le64_to_cpu(old.num_bytes));
 670                                 ret = btrfs_free_extent(trans, root,
 671                                                 disk_bytenr,
 672                                                 le64_to_cpu(old.disk_num_bytes),
 673                                                 leaf_start, root_owner,
 674                                                 root_gen, key.objectid, 0);
 675                                 BUG_ON(ret);
 676                                 *hint_byte = disk_bytenr;
 677                         }
 678                 }
 679
 680                 if (search_start >= end) {
 681                         ret = 0;
 682                         goto out;
 683                 }
 684         }
 685 out:
 686         btrfs_free_path(path);
 687         if (locked_end > end) {
 688                 unlock_extent(&BTRFS_I(inode)->io_tree, end, locked_end - 1,
 689                               GFP_NOFS);
 690         }
 691         btrfs_check_file(root, inode);
 692         return ret;
 693 }
 694
 695 static int extent_mergeable(struct extent_buffer *leaf, int slot,
 696                             u64 objectid, u64 bytenr, u64 *start, u64 *end)
 697 {
 698         struct btrfs_file_extent_item *fi;
 699         struct btrfs_key key;
 700         u64 extent_end;
 701
 702         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
 703                 return 0;
 704
 705         btrfs_item_key_to_cpu(leaf, &key, slot);
 706         if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
 707                 return 0;
 708
 709         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
 710         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
 711             btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
 712             btrfs_file_extent_compression(leaf, fi) ||
 713             btrfs_file_extent_encryption(leaf, fi) ||
 714             btrfs_file_extent_other_encoding(leaf, fi))
 715                 return 0;
 716
 717         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 718         if ((*start && *start != key.offset) || (*end && *end != extent_end))
 719                 return 0;
 720
 721         *start = key.offset;
 722         *end = extent_end;
 723         return 1;
 724 }
 725
 726 /*
 727  * Mark extent in the range start - end as written.
 728  *
 729  * This changes extent type from 'pre-allocated' to 'regular'. If only
 730  * part of extent is marked as written, the extent will be split into
 731  * two or three.
 732  */
 733 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
 734                               struct btrfs_root *root,
 735                               struct inode *inode, u64 start, u64 end)
 736 {
 737         struct extent_buffer *leaf;
 738         struct btrfs_path *path;
 739         struct btrfs_file_extent_item *fi;
 740         struct btrfs_key key;
 741         u64 bytenr;
 742         u64 num_bytes;
 743         u64 extent_end;
 744         u64 extent_offset;
 745         u64 other_start;
 746         u64 other_end;
 747         u64 split = start;
 748         u64 locked_end = end;
 749         u64 orig_parent;
 750         int extent_type;
 751         int split_end = 1;
 752         int ret;
 753
 754         btrfs_drop_extent_cache(inode, start, end - 1, 0);
 755
 756         path = btrfs_alloc_path();
 757         BUG_ON(!path);
 758 again:
 759         key.objectid = inode->i_ino;
 760         key.type = BTRFS_EXTENT_DATA_KEY;
 761         if (split == start)
 762                 key.offset = split;
 763         else
 764                 key.offset = split - 1;
 765
 766         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 767         if (ret > 0 && path->slots[0] > 0)
 768                 path->slots[0]--;
 769
 770         leaf = path->nodes[0];
 771         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 772         BUG_ON(key.objectid != inode->i_ino ||
 773                key.type != BTRFS_EXTENT_DATA_KEY);
 774         fi = btrfs_item_ptr(leaf, path->slots[0],
 775                             struct btrfs_file_extent_item);
 776         extent_type = btrfs_file_extent_type(leaf, fi);
 777         BUG_ON(extent_type != BTRFS_FILE_EXTENT_PREALLOC);
 778         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 779         BUG_ON(key.offset > start || extent_end < end);
 780
 781         bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 782         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
 783         extent_offset = btrfs_file_extent_offset(leaf, fi);
 784
 785         if (key.offset == start)
 786                 split = end;
 787
 788         if (key.offset == start && extent_end == end) {
 789                 int del_nr = 0;
 790                 int del_slot = 0;
 791                 u64 leaf_owner = btrfs_header_owner(leaf);
 792                 u64 leaf_gen = btrfs_header_generation(leaf);
 793                 other_start = end;
 794                 other_end = 0;
 795                 if (extent_mergeable(leaf, path->slots[0] + 1, inode->i_ino,
 796                                      bytenr, &other_start, &other_end)) {
 797                         extent_end = other_end;
 798                         del_slot = path->slots[0] + 1;
 799                         del_nr++;
 800                         ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
 801                                                 leaf->start, leaf_owner,
 802                                                 leaf_gen, inode->i_ino, 0);
 803                         BUG_ON(ret);
 804                 }
 805                 other_start = 0;
 806                 other_end = start;
 807                 if (extent_mergeable(leaf, path->slots[0] - 1, inode->i_ino,
 808                                      bytenr, &other_start, &other_end)) {
 809                         key.offset = other_start;
 810                         del_slot = path->slots[0];
 811                         del_nr++;
 812                         ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
 813                                                 leaf->start, leaf_owner,
 814                                                 leaf_gen, inode->i_ino, 0);
 815                         BUG_ON(ret);
 816                 }
 817                 split_end = 0;
 818                 if (del_nr == 0) {
 819                         btrfs_set_file_extent_type(leaf, fi,
 820                                                    BTRFS_FILE_EXTENT_REG);
 821                         goto done;
 822                 }
 823
 824                 fi = btrfs_item_ptr(leaf, del_slot - 1,
 825                                     struct btrfs_file_extent_item);
 826                 btrfs_set_file_extent_type(leaf, fi, BTRFS_FILE_EXTENT_REG);
 827                 btrfs_set_file_extent_num_bytes(leaf, fi,
 828                                                 extent_end - key.offset);
 829                 btrfs_mark_buffer_dirty(leaf);
 830
 831                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
 832                 BUG_ON(ret);
 833                 goto done;
 834         } else if (split == start) {
 835                 if (locked_end < extent_end) {
 836                         ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
 837                                         locked_end, extent_end - 1, GFP_NOFS);
 838                         if (!ret) {
 839                                 btrfs_release_path(root, path);
 840                                 lock_extent(&BTRFS_I(inode)->io_tree,
 841                                         locked_end, extent_end - 1, GFP_NOFS);
 842                                 locked_end = extent_end;
 843                                 goto again;
 844                         }
 845                         locked_end = extent_end;
 846                 }
 847                 btrfs_set_file_extent_num_bytes(leaf, fi, split - key.offset);
 848                 extent_offset += split - key.offset;
 849         } else  {
 850                 BUG_ON(key.offset != start);
 851                 btrfs_set_file_extent_offset(leaf, fi, extent_offset +
 852                                              split - key.offset);
 853                 btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - split);
 854                 key.offset = split;
 855                 btrfs_set_item_key_safe(trans, root, path, &key);
 856                 extent_end = split;
 857         }
 858
 859         if (extent_end == end) {
 860                 split_end = 0;
 861                 extent_type = BTRFS_FILE_EXTENT_REG;
 862         }
 863         if (extent_end == end && split == start) {
 864                 other_start = end;
 865                 other_end = 0;
 866                 if (extent_mergeable(leaf, path->slots[0] + 1, inode->i_ino,
 867                                      bytenr, &other_start, &other_end)) {
 868                         path->slots[0]++;
 869                         fi = btrfs_item_ptr(leaf, path->slots[0],
 870                                             struct btrfs_file_extent_item);
 871                         key.offset = split;
 872                         btrfs_set_item_key_safe(trans, root, path, &key);
 873                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
 874                         btrfs_set_file_extent_num_bytes(leaf, fi,
 875                                                         other_end - split);
 876                         goto done;
 877                 }
 878         }
 879         if (extent_end == end && split == end) {
 880                 other_start = 0;
 881                 other_end = start;
 882                 if (extent_mergeable(leaf, path->slots[0] - 1 , inode->i_ino,
 883                                      bytenr, &other_start, &other_end)) {
 884                         path->slots[0]--;
 885                         fi = btrfs_item_ptr(leaf, path->slots[0],
 886                                             struct btrfs_file_extent_item);
 887                         btrfs_set_file_extent_num_bytes(leaf, fi, extent_end -
 888                                                         other_start);
 889                         goto done;
 890                 }
 891         }
 892
 893         btrfs_mark_buffer_dirty(leaf);
 894
 895         orig_parent = leaf->start;
 896         ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes,
 897                                    orig_parent, root->root_key.objectid,
 898                                    trans->transid, inode->i_ino);
 899         BUG_ON(ret);
 900         btrfs_release_path(root, path);
 901
 902         key.offset = start;
 903         ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*fi));
 904         BUG_ON(ret);
 905
 906         leaf = path->nodes[0];
 907         fi = btrfs_item_ptr(leaf, path->slots[0],
 908                             struct btrfs_file_extent_item);
 909         btrfs_set_file_extent_generation(leaf, fi, trans->transid);
 910         btrfs_set_file_extent_type(leaf, fi, extent_type);
 911         btrfs_set_file_extent_disk_bytenr(leaf, fi, bytenr);
 912         btrfs_set_file_extent_disk_num_bytes(leaf, fi, num_bytes);
 913         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
 914         btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - key.offset);
 915         btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
 916         btrfs_set_file_extent_compression(leaf, fi, 0);
 917         btrfs_set_file_extent_encryption(leaf, fi, 0);
 918         btrfs_set_file_extent_other_encoding(leaf, fi, 0);
 919
 920         if (orig_parent != leaf->start) {
 921                 ret = btrfs_update_extent_ref(trans, root, bytenr,
 922                                               orig_parent, leaf->start,
 923                                               root->root_key.objectid,
 924                                               trans->transid, inode->i_ino);
 925                 BUG_ON(ret);
 926         }
 927 done:
 928         btrfs_mark_buffer_dirty(leaf);
 929         btrfs_release_path(root, path);
 930         if (split_end && split == start) {
 931                 split = end;
 932                 goto again;
 933         }
 934         if (locked_end > end) {
 935                 unlock_extent(&BTRFS_I(inode)->io_tree, end, locked_end - 1,
 936                               GFP_NOFS);
 937         }
 938         btrfs_free_path(path);
 939         return 0;
 940 }
 941
 942 /*
 943  * this gets pages into the page cache and locks them down, it also properly
 944  * waits for data=ordered extents to finish before allowing the pages to be
 945  * modified.
 946  */
 947 static int noinline prepare_pages(struct btrfs_root *root, struct file *file,
 948                          struct page **pages, size_t num_pages,
 949                          loff_t pos, unsigned long first_index,
 950                          unsigned long last_index, size_t write_bytes)
 951 {
 952         int i;
 953         unsigned long index = pos >> PAGE_CACHE_SHIFT;
 954         struct inode *inode = fdentry(file)->d_inode;
 955         int err = 0;
 956         u64 start_pos;
 957         u64 last_pos;
 958
 959         start_pos = pos & ~((u64)root->sectorsize - 1);
 960         last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
 961
 962         if (start_pos > inode->i_size) {
 963                 err = btrfs_cont_expand(inode, start_pos);
 964                 if (err)
 965                         return err;
 966         }
 967
 968         memset(pages, 0, num_pages * sizeof(struct page *));
 969 again:
 970         for (i = 0; i < num_pages; i++) {
 971                 pages[i] = grab_cache_page(inode->i_mapping, index + i);
 972                 if (!pages[i]) {
 973                         err = -ENOMEM;
 974                         BUG_ON(1);
 975                 }
 976                 wait_on_page_writeback(pages[i]);
 977         }
 978         if (start_pos < inode->i_size) {
 979                 struct btrfs_ordered_extent *ordered;
 980                 lock_extent(&BTRFS_I(inode)->io_tree,
 981                             start_pos, last_pos - 1, GFP_NOFS);
 982                 ordered = btrfs_lookup_first_ordered_extent(inode, last_pos -1);
 983                 if (ordered &&
 984                     ordered->file_offset + ordered->len > start_pos &&
 985                     ordered->file_offset < last_pos) {
 986                         btrfs_put_ordered_extent(ordered);
 987                         unlock_extent(&BTRFS_I(inode)->io_tree,
 988                                       start_pos, last_pos - 1, GFP_NOFS);
 989                         for (i = 0; i < num_pages; i++) {
 990                                 unlock_page(pages[i]);
 991                                 page_cache_release(pages[i]);
 992                         }
 993                         btrfs_wait_ordered_range(inode, start_pos,
 994                                                  last_pos - start_pos);
 995                         goto again;
 996                 }
 997                 if (ordered)
 998                         btrfs_put_ordered_extent(ordered);
 999
1000                 clear_extent_bits(&BTRFS_I(inode)->io_tree, start_pos,
1001                                   last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC,
1002                                   GFP_NOFS);
1003                 unlock_extent(&BTRFS_I(inode)->io_tree,
1004                               start_pos, last_pos - 1, GFP_NOFS);
1005         }
1006         for (i = 0; i < num_pages; i++) {
1007                 clear_page_dirty_for_io(pages[i]);
1008                 set_page_extent_mapped(pages[i]);
1009                 WARN_ON(!PageLocked(pages[i]));
1010         }
1011         return 0;
1012 }
1013
1014 static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
1015                                 size_t count, loff_t *ppos)
1016 {
1017         loff_t pos;
1018         loff_t start_pos;
1019         ssize_t num_written = 0;
1020         ssize_t err = 0;
1021         int ret = 0;
1022         struct inode *inode = fdentry(file)->d_inode;
1023         struct btrfs_root *root = BTRFS_I(inode)->root;
1024         struct page **pages = NULL;
1025         int nrptrs;
1026         struct page *pinned[2];
1027         unsigned long first_index;
1028         unsigned long last_index;
1029         int will_write;
1030
1031         will_write = ((file->f_flags & O_SYNC) || IS_SYNC(inode) ||
1032                       (file->f_flags & O_DIRECT));
1033
1034         nrptrs = min((count + PAGE_CACHE_SIZE - 1) / PAGE_CACHE_SIZE,
1035                      PAGE_CACHE_SIZE / (sizeof(struct page *)));
1036         pinned[0] = NULL;
1037         pinned[1] = NULL;
1038
1039         pos = *ppos;
1040         start_pos = pos;
1041
1042         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
1043         current->backing_dev_info = inode->i_mapping->backing_dev_info;
1044         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
1045         if (err)
1046                 goto out_nolock;
1047         if (count == 0)
1048                 goto out_nolock;
1049
1050         err = file_remove_suid(file);
1051         if (err)
1052                 goto out_nolock;
1053         file_update_time(file);
1054
1055         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
1056
1057         mutex_lock(&inode->i_mutex);
1058         first_index = pos >> PAGE_CACHE_SHIFT;
1059         last_index = (pos + count) >> PAGE_CACHE_SHIFT;
1060
1061         /*
1062          * if this is a nodatasum mount, force summing off for the inode
1063          * all the time.  That way a later mount with summing on won't
1064          * get confused
1065          */
1066         if (btrfs_test_opt(root, NODATASUM))
1067                 btrfs_set_flag(inode, NODATASUM);
1068
1069         /*
1070          * there are lots of better ways to do this, but this code
1071          * makes sure the first and last page in the file range are
1072          * up to date and ready for cow
1073          */
1074         if ((pos & (PAGE_CACHE_SIZE - 1))) {
1075                 pinned[0] = grab_cache_page(inode->i_mapping, first_index);
1076                 if (!PageUptodate(pinned[0])) {
1077                         ret = btrfs_readpage(NULL, pinned[0]);
1078                         BUG_ON(ret);
1079                         wait_on_page_locked(pinned[0]);
1080                 } else {
1081                         unlock_page(pinned[0]);
1082                 }
1083         }
1084         if ((pos + count) & (PAGE_CACHE_SIZE - 1)) {
1085                 pinned[1] = grab_cache_page(inode->i_mapping, last_index);
1086                 if (!PageUptodate(pinned[1])) {
1087                         ret = btrfs_readpage(NULL, pinned[1]);
1088                         BUG_ON(ret);
1089                         wait_on_page_locked(pinned[1]);
1090                 } else {
1091                         unlock_page(pinned[1]);
1092                 }
1093         }
1094
1095         while(count > 0) {
1096                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
1097                 size_t write_bytes = min(count, nrptrs *
1098                                         (size_t)PAGE_CACHE_SIZE -
1099                                          offset);
1100                 size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
1101                                         PAGE_CACHE_SHIFT;
1102
1103                 WARN_ON(num_pages > nrptrs);
1104                 memset(pages, 0, sizeof(pages));
1105
1106                 ret = btrfs_check_free_space(root, write_bytes, 0);
1107                 if (ret)
1108                         goto out;
1109
1110                 ret = prepare_pages(root, file, pages, num_pages,
1111                                     pos, first_index, last_index,
1112                                     write_bytes);
1113                 if (ret)
1114                         goto out;
1115
1116                 ret = btrfs_copy_from_user(pos, num_pages,
1117                                            write_bytes, pages, buf);
1118                 if (ret) {
1119                         btrfs_drop_pages(pages, num_pages);
1120                         goto out;
1121                 }
1122
1123                 ret = dirty_and_release_pages(NULL, root, file, pages,
1124                                               num_pages, pos, write_bytes);
1125                 btrfs_drop_pages(pages, num_pages);
1126                 if (ret)
1127                         goto out;
1128
1129                 if (will_write) {
1130                         btrfs_fdatawrite_range(inode->i_mapping, pos,
1131                                                pos + write_bytes - 1,
1132                                                WB_SYNC_NONE);
1133                 } else {
1134                         balance_dirty_pages_ratelimited_nr(inode->i_mapping,
1135                                                            num_pages);
1136                         if (num_pages <
1137                             (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
1138                                 btrfs_btree_balance_dirty(root, 1);
1139                         btrfs_throttle(root);
1140                 }
1141
1142                 buf += write_bytes;
1143                 count -= write_bytes;
1144                 pos += write_bytes;
1145                 num_written += write_bytes;
1146
1147                 cond_resched();
1148         }
1149 out:
1150         mutex_unlock(&inode->i_mutex);
1151
1152 out_nolock:
1153         kfree(pages);
1154         if (pinned[0])
1155                 page_cache_release(pinned[0]);
1156         if (pinned[1])
1157                 page_cache_release(pinned[1]);
1158         *ppos = pos;
1159
1160         if (num_written > 0 && will_write) {
1161                 struct btrfs_trans_handle *trans;
1162
1163                 err = btrfs_wait_ordered_range(inode, start_pos, num_written);
1164                 if (err)
1165                         num_written = err;
1166
1167                 if ((file->f_flags & O_SYNC) || IS_SYNC(inode)) {
1168                         trans = btrfs_start_transaction(root, 1);
1169                         ret = btrfs_log_dentry_safe(trans, root,
1170                                                     file->f_dentry);
1171                         if (ret == 0) {
1172                                 btrfs_sync_log(trans, root);
1173                                 btrfs_end_transaction(trans, root);
1174                         } else {
1175                                 btrfs_commit_transaction(trans, root);
1176                         }
1177                 }
1178                 if (file->f_flags & O_DIRECT) {
1179                         invalidate_mapping_pages(inode->i_mapping,
1180                               start_pos >> PAGE_CACHE_SHIFT,
1181                              (start_pos + num_written - 1) >> PAGE_CACHE_SHIFT);
1182                 }
1183         }
1184         current->backing_dev_info = NULL;
1185         return num_written ? num_written : err;
1186 }
1187
1188 int btrfs_release_file(struct inode * inode, struct file * filp)
1189 {
1190         if (filp->private_data)
1191                 btrfs_ioctl_trans_end(filp);
1192         return 0;
1193 }
1194
1195 /*
1196  * fsync call for both files and directories.  This logs the inode into
1197  * the tree log instead of forcing full commits whenever possible.
1198  *
1199  * It needs to call filemap_fdatawait so that all ordered extent updates are
1200  * in the metadata btree are up to date for copying to the log.
1201  *
1202  * It drops the inode mutex before doing the tree log commit.  This is an
1203  * important optimization for directories because holding the mutex prevents
1204  * new operations on the dir while we write to disk.
1205  */
1206 int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
1207 {
1208         struct inode *inode = dentry->d_inode;
1209         struct btrfs_root *root = BTRFS_I(inode)->root;
1210         int ret = 0;
1211         struct btrfs_trans_handle *trans;
1212
1213         /*
1214          * check the transaction that last modified this inode
1215          * and see if its already been committed
1216          */
1217         if (!BTRFS_I(inode)->last_trans)
1218                 goto out;
1219
1220         mutex_lock(&root->fs_info->trans_mutex);
1221         if (BTRFS_I(inode)->last_trans <=
1222             root->fs_info->last_trans_committed) {
1223                 BTRFS_I(inode)->last_trans = 0;
1224                 mutex_unlock(&root->fs_info->trans_mutex);
1225                 goto out;
1226         }
1227         mutex_unlock(&root->fs_info->trans_mutex);
1228
1229         root->fs_info->tree_log_batch++;
1230         filemap_fdatawait(inode->i_mapping);
1231         root->fs_info->tree_log_batch++;
1232
1233         /*
1234          * ok we haven't committed the transaction yet, lets do a commit
1235          */
1236         if (file->private_data)
1237                 btrfs_ioctl_trans_end(file);
1238
1239         trans = btrfs_start_transaction(root, 1);
1240         if (!trans) {
1241                 ret = -ENOMEM;
1242                 goto out;
1243         }
1244
1245         ret = btrfs_log_dentry_safe(trans, root, file->f_dentry);
1246         if (ret < 0) {
1247                 goto out;
1248         }
1249
1250         /* we've logged all the items and now have a consistent
1251          * version of the file in the log.  It is possible that
1252          * someone will come in and modify the file, but that's
1253          * fine because the log is consistent on disk, and we
1254          * have references to all of the file's extents
1255          *
1256          * It is possible that someone will come in and log the
1257          * file again, but that will end up using the synchronization
1258          * inside btrfs_sync_log to keep things safe.
1259          */
1260         mutex_unlock(&file->f_dentry->d_inode->i_mutex);
1261
1262         if (ret > 0) {
1263                 ret = btrfs_commit_transaction(trans, root);
1264         } else {
1265                 btrfs_sync_log(trans, root);
1266                 ret = btrfs_end_transaction(trans, root);
1267         }
1268         mutex_lock(&file->f_dentry->d_inode->i_mutex);
1269 out:
1270         return ret > 0 ? EIO : ret;
1271 }
1272
1273 static struct vm_operations_struct btrfs_file_vm_ops = {
1274         .fault          = filemap_fault,
1275         .page_mkwrite   = btrfs_page_mkwrite,
1276 };
1277
1278 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
1279 {
1280         vma->vm_ops = &btrfs_file_vm_ops;
1281         file_accessed(filp);
1282         return 0;
1283 }
1284
1285 struct file_operations btrfs_file_operations = {
1286         .llseek         = generic_file_llseek,
1287         .read           = do_sync_read,
1288         .aio_read       = generic_file_aio_read,
1289         .splice_read    = generic_file_splice_read,
1290         .write          = btrfs_file_write,
1291         .mmap           = btrfs_file_mmap,
1292         .open           = generic_file_open,
1293         .release        = btrfs_release_file,
1294         .fsync          = btrfs_sync_file,
1295         .unlocked_ioctl = btrfs_ioctl,
1296 #ifdef CONFIG_COMPAT
1297         .compat_ioctl   = btrfs_ioctl,
1298 #endif
1299 };