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/module.h>
  20 #include <linux/buffer_head.h>
  21 #include <linux/fs.h>
  22 #include <linux/pagemap.h>
  23 #include <linux/highmem.h>
  24 #include <linux/time.h>
  25 #include <linux/init.h>
  26 #include <linux/string.h>
  27 #include <linux/smp_lock.h>
  28 #include <linux/backing-dev.h>
  29 #include <linux/mpage.h>
  30 #include <linux/swap.h>
  31 #include <linux/writeback.h>
  32 #include <linux/statfs.h>
  33 #include <linux/compat.h>
  34 #include "ctree.h"
  35 #include "disk-io.h"
  36 #include "transaction.h"
  37 #include "btrfs_inode.h"
  38 #include "ioctl.h"
  39 #include "print-tree.h"
  40
  41
  42 static int btrfs_copy_from_user(loff_t pos, int num_pages, int write_bytes,
  43                                 struct page **prepared_pages,
  44                                 const char __user * buf)
  45 {
  46         long page_fault = 0;
  47         int i;
  48         int offset = pos & (PAGE_CACHE_SIZE - 1);
  49
  50         for (i = 0; i < num_pages && write_bytes > 0; i++, offset = 0) {
  51                 size_t count = min_t(size_t,
  52                                      PAGE_CACHE_SIZE - offset, write_bytes);
  53                 struct page *page = prepared_pages[i];
  54                 fault_in_pages_readable(buf, count);
  55
  56                 /* Copy data from userspace to the current page */
  57                 kmap(page);
  58                 page_fault = __copy_from_user(page_address(page) + offset,
  59                                               buf, count);
  60                 /* Flush processor's dcache for this page */
  61                 flush_dcache_page(page);
  62                 kunmap(page);
  63                 buf += count;
  64                 write_bytes -= count;
  65
  66                 if (page_fault)
  67                         break;
  68         }
  69         return page_fault ? -EFAULT : 0;
  70 }
  71
  72 static void btrfs_drop_pages(struct page **pages, size_t num_pages)
  73 {
  74         size_t i;
  75         for (i = 0; i < num_pages; i++) {
  76                 if (!pages[i])
  77                         break;
  78                 unlock_page(pages[i]);
  79                 mark_page_accessed(pages[i]);
  80                 page_cache_release(pages[i]);
  81         }
  82 }
  83
  84 static int dirty_and_release_pages(struct btrfs_trans_handle *trans,
  85                                    struct btrfs_root *root,
  86                                    struct file *file,
  87                                    struct page **pages,
  88                                    size_t num_pages,
  89                                    loff_t pos,
  90                                    size_t write_bytes)
  91 {
  92         int i;
  93         int offset;
  94         int err = 0;
  95         int ret;
  96         int this_write;
  97         struct inode *inode = file->f_path.dentry->d_inode;
  98         struct buffer_head *bh;
  99         struct btrfs_file_extent_item *ei;
 100
 101         for (i = 0; i < num_pages; i++) {
 102                 offset = pos & (PAGE_CACHE_SIZE -1);
 103                 this_write = min((size_t)PAGE_CACHE_SIZE - offset, write_bytes);
 104                 /* FIXME, one block at a time */
 105
 106                 bh = page_buffers(pages[i]);
 107
 108                 if (buffer_mapped(bh) && bh->b_blocknr == 0) {
 109                         struct btrfs_key key;
 110                         struct btrfs_path *path;
 111                         char *ptr, *kaddr;
 112                         u32 datasize;
 113
 114                         mutex_lock(&root->fs_info->fs_mutex);
 115                         trans = btrfs_start_transaction(root, 1);
 116                         btrfs_set_trans_block_group(trans, inode);
 117
 118                         /* create an inline extent, and copy the data in */
 119                         path = btrfs_alloc_path();
 120                         BUG_ON(!path);
 121                         key.objectid = inode->i_ino;
 122                         key.offset = pages[i]->index << PAGE_CACHE_SHIFT;
 123                         key.flags = 0;
 124                         btrfs_set_key_type(&key, BTRFS_EXTENT_DATA_KEY);
 125                         BUG_ON(write_bytes >= PAGE_CACHE_SIZE);
 126                         datasize = offset +
 127                                 btrfs_file_extent_calc_inline_size(write_bytes);
 128
 129                         ret = btrfs_insert_empty_item(trans, root, path, &key,
 130                                                       datasize);
 131                         BUG_ON(ret);
 132                         ei = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]),
 133                                path->slots[0], struct btrfs_file_extent_item);
 134                         btrfs_set_file_extent_generation(ei, trans->transid);
 135                         btrfs_set_file_extent_type(ei,
 136                                                    BTRFS_FILE_EXTENT_INLINE);
 137                         ptr = btrfs_file_extent_inline_start(ei);
 138
 139                         kaddr = kmap_atomic(bh->b_page, KM_USER0);
 140                         btrfs_memcpy(root, path->nodes[0]->b_data,
 141                                      ptr, kaddr + bh_offset(bh),
 142                                      offset + write_bytes);
 143                         kunmap_atomic(kaddr, KM_USER0);
 144
 145                         mark_buffer_dirty(path->nodes[0]);
 146                         btrfs_free_path(path);
 147                         ret = btrfs_end_transaction(trans, root);
 148                         BUG_ON(ret);
 149                         mutex_unlock(&root->fs_info->fs_mutex);
 150                 }
 151
 152                 ret = btrfs_commit_write(file, pages[i], offset,
 153                                          offset + this_write);
 154                 pos += this_write;
 155                 if (ret) {
 156                         err = ret;
 157                         goto failed;
 158                 }
 159                 WARN_ON(this_write > write_bytes);
 160                 write_bytes -= this_write;
 161         }
 162 failed:
 163         return err;
 164 }
 165
 166 /*
 167  * this is very complex, but the basic idea is to drop all extents
 168  * in the range start - end.  hint_block is filled in with a block number
 169  * that would be a good hint to the block allocator for this file.
 170  *
 171  * If an extent intersects the range but is not entirely inside the range
 172  * it is either truncated or split.  Anything entirely inside the range
 173  * is deleted from the tree.
 174  */
 175 int btrfs_drop_extents(struct btrfs_trans_handle *trans,
 176                        struct btrfs_root *root, struct inode *inode,
 177                        u64 start, u64 end, u64 *hint_block)
 178 {
 179         int ret;
 180         struct btrfs_key key;
 181         struct btrfs_leaf *leaf;
 182         int slot;
 183         struct btrfs_file_extent_item *extent;
 184         u64 extent_end = 0;
 185         int keep;
 186         struct btrfs_file_extent_item old;
 187         struct btrfs_path *path;
 188         u64 search_start = start;
 189         int bookend;
 190         int found_type;
 191         int found_extent;
 192         int found_inline;
 193
 194         path = btrfs_alloc_path();
 195         if (!path)
 196                 return -ENOMEM;
 197         while(1) {
 198                 btrfs_release_path(root, path);
 199                 ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
 200                                                search_start, -1);
 201                 if (ret < 0)
 202                         goto out;
 203                 if (ret > 0) {
 204                         if (path->slots[0] == 0) {
 205                                 ret = 0;
 206                                 goto out;
 207                         }
 208                         path->slots[0]--;
 209                 }
 210                 keep = 0;
 211                 bookend = 0;
 212                 found_extent = 0;
 213                 found_inline = 0;
 214                 extent = NULL;
 215                 leaf = btrfs_buffer_leaf(path->nodes[0]);
 216                 slot = path->slots[0];
 217                 btrfs_disk_key_to_cpu(&key, &leaf->items[slot].key);
 218                 if (key.offset >= end || key.objectid != inode->i_ino) {
 219                         ret = 0;
 220                         goto out;
 221                 }
 222                 if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY) {
 223                         ret = 0;
 224                         goto out;
 225                 }
 226                 extent = btrfs_item_ptr(leaf, slot,
 227                                         struct btrfs_file_extent_item);
 228                 found_type = btrfs_file_extent_type(extent);
 229                 if (found_type == BTRFS_FILE_EXTENT_REG) {
 230                         extent_end = key.offset +
 231                                 (btrfs_file_extent_num_blocks(extent) <<
 232                                  inode->i_blkbits);
 233                         found_extent = 1;
 234                 } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
 235                         found_inline = 1;
 236                         extent_end = key.offset +
 237                              btrfs_file_extent_inline_len(leaf->items + slot);
 238                 }
 239
 240                 /* we found nothing we can drop */
 241                 if (!found_extent && !found_inline) {
 242                         ret = 0;
 243                         goto out;
 244                 }
 245
 246                 /* we found nothing inside the range */
 247                 if (search_start >= extent_end) {
 248                         ret = 0;
 249                         goto out;
 250                 }
 251
 252                 /* FIXME, there's only one inline extent allowed right now */
 253                 if (found_inline) {
 254                         u64 mask = root->blocksize - 1;
 255                         search_start = (extent_end + mask) & ~mask;
 256                 } else
 257                         search_start = extent_end;
 258
 259                 if (end < extent_end && end >= key.offset) {
 260                         if (found_extent) {
 261                                 u64 disk_blocknr =
 262                                         btrfs_file_extent_disk_blocknr(extent);
 263                                 u64 disk_num_blocks =
 264                                       btrfs_file_extent_disk_num_blocks(extent);
 265                                 memcpy(&old, extent, sizeof(old));
 266                                 if (disk_blocknr != 0) {
 267                                         ret = btrfs_inc_extent_ref(trans, root,
 268                                                  disk_blocknr, disk_num_blocks);
 269                                         BUG_ON(ret);
 270                                 }
 271                         }
 272                         WARN_ON(found_inline);
 273                         bookend = 1;
 274                 }
 275
 276                 /* truncate existing extent */
 277                 if (start > key.offset) {
 278                         u64 new_num;
 279                         u64 old_num;
 280                         keep = 1;
 281                         WARN_ON(start & (root->blocksize - 1));
 282                         if (found_extent) {
 283                                 new_num = (start - key.offset) >>
 284                                         inode->i_blkbits;
 285                                 old_num = btrfs_file_extent_num_blocks(extent);
 286                                 *hint_block =
 287                                         btrfs_file_extent_disk_blocknr(extent);
 288                                 if (btrfs_file_extent_disk_blocknr(extent)) {
 289                                         inode->i_blocks -=
 290                                                 (old_num - new_num) << 3;
 291                                 }
 292                                 btrfs_set_file_extent_num_blocks(extent,
 293                                                                  new_num);
 294                                 mark_buffer_dirty(path->nodes[0]);
 295                         } else {
 296                                 WARN_ON(1);
 297                         }
 298                 }
 299                 /* delete the entire extent */
 300                 if (!keep) {
 301                         u64 disk_blocknr = 0;
 302                         u64 disk_num_blocks = 0;
 303                         u64 extent_num_blocks = 0;
 304                         if (found_extent) {
 305                                 disk_blocknr =
 306                                       btrfs_file_extent_disk_blocknr(extent);
 307                                 disk_num_blocks =
 308                                       btrfs_file_extent_disk_num_blocks(extent);
 309                                 extent_num_blocks =
 310                                       btrfs_file_extent_num_blocks(extent);
 311                                 *hint_block =
 312                                         btrfs_file_extent_disk_blocknr(extent);
 313                         }
 314                         ret = btrfs_del_item(trans, root, path);
 315                         BUG_ON(ret);
 316                         btrfs_release_path(root, path);
 317                         extent = NULL;
 318                         if (found_extent && disk_blocknr != 0) {
 319                                 inode->i_blocks -= extent_num_blocks << 3;
 320                                 ret = btrfs_free_extent(trans, root,
 321                                                         disk_blocknr,
 322                                                         disk_num_blocks, 0);
 323                         }
 324
 325                         BUG_ON(ret);
 326                         if (!bookend && search_start >= end) {
 327                                 ret = 0;
 328                                 goto out;
 329                         }
 330                         if (!bookend)
 331                                 continue;
 332                 }
 333                 /* create bookend, splitting the extent in two */
 334                 if (bookend && found_extent) {
 335                         struct btrfs_key ins;
 336                         ins.objectid = inode->i_ino;
 337                         ins.offset = end;
 338                         ins.flags = 0;
 339                         btrfs_set_key_type(&ins, BTRFS_EXTENT_DATA_KEY);
 340
 341                         btrfs_release_path(root, path);
 342                         ret = btrfs_insert_empty_item(trans, root, path, &ins,
 343                                                       sizeof(*extent));
 344                         BUG_ON(ret);
 345                         extent = btrfs_item_ptr(
 346                                     btrfs_buffer_leaf(path->nodes[0]),
 347                                     path->slots[0],
 348                                     struct btrfs_file_extent_item);
 349                         btrfs_set_file_extent_disk_blocknr(extent,
 350                                     btrfs_file_extent_disk_blocknr(&old));
 351                         btrfs_set_file_extent_disk_num_blocks(extent,
 352                                     btrfs_file_extent_disk_num_blocks(&old));
 353
 354                         btrfs_set_file_extent_offset(extent,
 355                                     btrfs_file_extent_offset(&old) +
 356                                     ((end - key.offset) >> inode->i_blkbits));
 357                         WARN_ON(btrfs_file_extent_num_blocks(&old) <
 358                                 (extent_end - end) >> inode->i_blkbits);
 359                         btrfs_set_file_extent_num_blocks(extent,
 360                                     (extent_end - end) >> inode->i_blkbits);
 361
 362                         btrfs_set_file_extent_type(extent,
 363                                                    BTRFS_FILE_EXTENT_REG);
 364                         btrfs_set_file_extent_generation(extent,
 365                                     btrfs_file_extent_generation(&old));
 366                         btrfs_mark_buffer_dirty(path->nodes[0]);
 367                         if (btrfs_file_extent_disk_blocknr(&old) != 0) {
 368                                 inode->i_blocks +=
 369                                       btrfs_file_extent_num_blocks(extent) << 3;
 370                         }
 371                         ret = 0;
 372                         goto out;
 373                 }
 374         }
 375 out:
 376         btrfs_free_path(path);
 377         return ret;
 378 }
 379
 380 /*
 381  * this gets pages into the page cache and locks them down
 382  */
 383 static int prepare_pages(struct btrfs_root *root,
 384                          struct file *file,
 385                          struct page **pages,
 386                          size_t num_pages,
 387                          loff_t pos,
 388                          unsigned long first_index,
 389                          unsigned long last_index,
 390                          size_t write_bytes,
 391                          u64 alloc_extent_start)
 392 {
 393         int i;
 394         unsigned long index = pos >> PAGE_CACHE_SHIFT;
 395         struct inode *inode = file->f_path.dentry->d_inode;
 396         int offset;
 397         int err = 0;
 398         int this_write;
 399         struct buffer_head *bh;
 400         struct buffer_head *head;
 401         loff_t isize = i_size_read(inode);
 402
 403         memset(pages, 0, num_pages * sizeof(struct page *));
 404
 405         for (i = 0; i < num_pages; i++) {
 406                 pages[i] = grab_cache_page(inode->i_mapping, index + i);
 407                 if (!pages[i]) {
 408                         err = -ENOMEM;
 409                         goto failed_release;
 410                 }
 411                 cancel_dirty_page(pages[i], PAGE_CACHE_SIZE);
 412                 wait_on_page_writeback(pages[i]);
 413                 offset = pos & (PAGE_CACHE_SIZE -1);
 414                 this_write = min((size_t)PAGE_CACHE_SIZE - offset, write_bytes);
 415                 if (!page_has_buffers(pages[i])) {
 416                         create_empty_buffers(pages[i],
 417                                              root->fs_info->sb->s_blocksize,
 418                                              (1 << BH_Uptodate));
 419                 }
 420                 head = page_buffers(pages[i]);
 421                 bh = head;
 422                 do {
 423                         err = btrfs_map_bh_to_logical(root, bh,
 424                                                       alloc_extent_start);
 425                         BUG_ON(err);
 426                         if (err)
 427                                 goto failed_truncate;
 428                         bh = bh->b_this_page;
 429                         if (alloc_extent_start)
 430                                 alloc_extent_start++;
 431                 } while (bh != head);
 432                 pos += this_write;
 433                 WARN_ON(this_write > write_bytes);
 434                 write_bytes -= this_write;
 435         }
 436         return 0;
 437
 438 failed_release:
 439         btrfs_drop_pages(pages, num_pages);
 440         return err;
 441
 442 failed_truncate:
 443         btrfs_drop_pages(pages, num_pages);
 444         if (pos > isize)
 445                 vmtruncate(inode, isize);
 446         return err;
 447 }
 448
 449 static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
 450                                 size_t count, loff_t *ppos)
 451 {
 452         loff_t pos;
 453         size_t num_written = 0;
 454         int err = 0;
 455         int ret = 0;
 456         struct inode *inode = file->f_path.dentry->d_inode;
 457         struct btrfs_root *root = BTRFS_I(inode)->root;
 458         struct page *pages[8];
 459         struct page *pinned[2];
 460         unsigned long first_index;
 461         unsigned long last_index;
 462         u64 start_pos;
 463         u64 num_blocks;
 464         u64 alloc_extent_start;
 465         u64 hint_block;
 466         struct btrfs_trans_handle *trans;
 467         struct btrfs_key ins;
 468         pinned[0] = NULL;
 469         pinned[1] = NULL;
 470         if (file->f_flags & O_DIRECT)
 471                 return -EINVAL;
 472         pos = *ppos;
 473         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
 474         current->backing_dev_info = inode->i_mapping->backing_dev_info;
 475         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
 476         if (err)
 477                 goto out;
 478         if (count == 0)
 479                 goto out;
 480         err = remove_suid(file->f_path.dentry);
 481         if (err)
 482                 goto out;
 483         file_update_time(file);
 484
 485         start_pos = pos & ~((u64)PAGE_CACHE_SIZE - 1);
 486         num_blocks = (count + pos - start_pos + root->blocksize - 1) >>
 487                         inode->i_blkbits;
 488
 489         mutex_lock(&inode->i_mutex);
 490         first_index = pos >> PAGE_CACHE_SHIFT;
 491         last_index = (pos + count) >> PAGE_CACHE_SHIFT;
 492
 493         /*
 494          * there are lots of better ways to do this, but this code
 495          * makes sure the first and last page in the file range are
 496          * up to date and ready for cow
 497          */
 498         if ((pos & (PAGE_CACHE_SIZE - 1))) {
 499                 pinned[0] = grab_cache_page(inode->i_mapping, first_index);
 500                 if (!PageUptodate(pinned[0])) {
 501                         ret = btrfs_readpage(NULL, pinned[0]);
 502                         BUG_ON(ret);
 503                         wait_on_page_locked(pinned[0]);
 504                 } else {
 505                         unlock_page(pinned[0]);
 506                 }
 507         }
 508         if ((pos + count) & (PAGE_CACHE_SIZE - 1)) {
 509                 pinned[1] = grab_cache_page(inode->i_mapping, last_index);
 510                 if (!PageUptodate(pinned[1])) {
 511                         ret = btrfs_readpage(NULL, pinned[1]);
 512                         BUG_ON(ret);
 513                         wait_on_page_locked(pinned[1]);
 514                 } else {
 515                         unlock_page(pinned[1]);
 516                 }
 517         }
 518
 519         mutex_lock(&root->fs_info->fs_mutex);
 520         trans = btrfs_start_transaction(root, 1);
 521         if (!trans) {
 522                 err = -ENOMEM;
 523                 mutex_unlock(&root->fs_info->fs_mutex);
 524                 goto out_unlock;
 525         }
 526         btrfs_set_trans_block_group(trans, inode);
 527         /* FIXME blocksize != 4096 */
 528         inode->i_blocks += num_blocks << 3;
 529         hint_block = 0;
 530
 531         /* FIXME...EIEIO, ENOSPC and more */
 532
 533         /* step one, delete the existing extents in this range */
 534         if (start_pos < inode->i_size) {
 535                 /* FIXME blocksize != pagesize */
 536                 ret = btrfs_drop_extents(trans, root, inode,
 537                                          start_pos,
 538                                          (pos + count + root->blocksize -1) &
 539                                          ~((u64)root->blocksize - 1),
 540                                          &hint_block);
 541                 BUG_ON(ret);
 542         }
 543
 544         /* insert any holes we need to create */
 545         if (inode->i_size < start_pos) {
 546                 u64 last_pos_in_file;
 547                 u64 hole_size;
 548                 u64 mask = root->blocksize - 1;
 549                 last_pos_in_file = (inode->i_size + mask) & ~mask;
 550                 hole_size = (start_pos - last_pos_in_file + mask) & ~mask;
 551                 hole_size >>= inode->i_blkbits;
 552                 if (last_pos_in_file < start_pos) {
 553                         ret = btrfs_insert_file_extent(trans, root,
 554                                                        inode->i_ino,
 555                                                        last_pos_in_file,
 556                                                        0, 0, hole_size);
 557                 }
 558                 BUG_ON(ret);
 559         }
 560
 561         /*
 562          * either allocate an extent for the new bytes or setup the key
 563          * to show we are doing inline data in the extent
 564          */
 565         if (inode->i_size >= PAGE_CACHE_SIZE || pos + count < inode->i_size ||
 566             pos + count - start_pos > BTRFS_MAX_INLINE_DATA_SIZE(root)) {
 567                 ret = btrfs_alloc_extent(trans, root, inode->i_ino,
 568                                          num_blocks, hint_block, (u64)-1,
 569                                          &ins, 1);
 570                 BUG_ON(ret);
 571                 ret = btrfs_insert_file_extent(trans, root, inode->i_ino,
 572                                        start_pos, ins.objectid, ins.offset,
 573                                        ins.offset);
 574                 BUG_ON(ret);
 575         } else {
 576                 ins.offset = 0;
 577                 ins.objectid = 0;
 578         }
 579         BUG_ON(ret);
 580         alloc_extent_start = ins.objectid;
 581         ret = btrfs_end_transaction(trans, root);
 582         mutex_unlock(&root->fs_info->fs_mutex);
 583
 584         while(count > 0) {
 585                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
 586                 size_t write_bytes = min(count,
 587                                          (size_t)PAGE_CACHE_SIZE - offset);
 588                 size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
 589                                         PAGE_CACHE_SHIFT;
 590
 591                 memset(pages, 0, sizeof(pages));
 592                 ret = prepare_pages(root, file, pages, num_pages,
 593                                     pos, first_index, last_index,
 594                                     write_bytes, alloc_extent_start);
 595                 BUG_ON(ret);
 596
 597                 /* FIXME blocks != pagesize */
 598                 if (alloc_extent_start)
 599                         alloc_extent_start += num_pages;
 600                 ret = btrfs_copy_from_user(pos, num_pages,
 601                                            write_bytes, pages, buf);
 602                 BUG_ON(ret);
 603
 604                 ret = dirty_and_release_pages(NULL, root, file, pages,
 605                                               num_pages, pos, write_bytes);
 606                 BUG_ON(ret);
 607                 btrfs_drop_pages(pages, num_pages);
 608
 609                 buf += write_bytes;
 610                 count -= write_bytes;
 611                 pos += write_bytes;
 612                 num_written += write_bytes;
 613
 614                 balance_dirty_pages_ratelimited(inode->i_mapping);
 615                 btrfs_btree_balance_dirty(root);
 616                 cond_resched();
 617         }
 618 out_unlock:
 619         mutex_unlock(&inode->i_mutex);
 620 out:
 621         if (pinned[0])
 622                 page_cache_release(pinned[0]);
 623         if (pinned[1])
 624                 page_cache_release(pinned[1]);
 625         *ppos = pos;
 626         current->backing_dev_info = NULL;
 627         mark_inode_dirty(inode);
 628         return num_written ? num_written : err;
 629 }
 630
 631 static int btrfs_sync_file(struct file *file,
 632                            struct dentry *dentry, int datasync)
 633 {
 634         struct inode *inode = dentry->d_inode;
 635         struct btrfs_root *root = BTRFS_I(inode)->root;
 636         int ret;
 637         struct btrfs_trans_handle *trans;
 638
 639         /*
 640          * FIXME, use inode generation number to check if we can skip the
 641          * commit
 642          */
 643         mutex_lock(&root->fs_info->fs_mutex);
 644         trans = btrfs_start_transaction(root, 1);
 645         if (!trans) {
 646                 ret = -ENOMEM;
 647                 goto out;
 648         }
 649         ret = btrfs_commit_transaction(trans, root);
 650         mutex_unlock(&root->fs_info->fs_mutex);
 651 out:
 652         return ret > 0 ? EIO : ret;
 653 }
 654
 655 static struct vm_operations_struct btrfs_file_vm_ops = {
 656         .nopage         = filemap_nopage,
 657         .populate       = filemap_populate,
 658         .page_mkwrite   = btrfs_page_mkwrite,
 659 };
 660
 661 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
 662 {
 663         vma->vm_ops = &btrfs_file_vm_ops;
 664         file_accessed(filp);
 665         return 0;
 666 }
 667
 668 struct file_operations btrfs_file_operations = {
 669         .llseek         = generic_file_llseek,
 670         .read           = do_sync_read,
 671         .aio_read       = generic_file_aio_read,
 672         .write          = btrfs_file_write,
 673         .mmap           = btrfs_file_mmap,
 674         .open           = generic_file_open,
 675         .ioctl          = btrfs_ioctl,
 676         .fsync          = btrfs_sync_file,
 677 #ifdef CONFIG_COMPAT
 678         .compat_ioctl   = btrfs_compat_ioctl,
 679 #endif
 680 };
 681