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/buffer_head.h>
  20 #include <linux/fs.h>
  21 #include <linux/pagemap.h>
  22 #include <linux/highmem.h>
  23 #include <linux/time.h>
  24 #include <linux/init.h>
  25 #include <linux/string.h>
  26 #include <linux/smp_lock.h>
  27 #include <linux/backing-dev.h>
  28 #include <linux/mpage.h>
  29 #include <linux/swap.h>
  30 #include <linux/writeback.h>
  31 #include <linux/statfs.h>
  32 #include <linux/compat.h>
  33 #include <linux/version.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 insert_inline_extent(struct btrfs_trans_handle *trans,
  85                                 struct btrfs_root *root, struct inode *inode,
  86                                 u64 offset, ssize_t size,
  87                                 struct page *page, size_t page_offset)
  88 {
  89         struct btrfs_key key;
  90         struct btrfs_path *path;
  91         char *ptr, *kaddr;
  92         struct btrfs_file_extent_item *ei;
  93         u32 datasize;
  94         int err = 0;
  95         int ret;
  96
  97         path = btrfs_alloc_path();
  98         if (!path)
  99                 return -ENOMEM;
 100
 101         btrfs_set_trans_block_group(trans, inode);
 102
 103         key.objectid = inode->i_ino;
 104         key.offset = offset;
 105         key.flags = 0;
 106         btrfs_set_key_type(&key, BTRFS_EXTENT_DATA_KEY);
 107         BUG_ON(size >= PAGE_CACHE_SIZE);
 108         datasize = btrfs_file_extent_calc_inline_size(size);
 109
 110         ret = btrfs_insert_empty_item(trans, root, path, &key,
 111                                       datasize);
 112         if (ret) {
 113                 err = ret;
 114                 goto fail;
 115         }
 116         ei = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]),
 117                path->slots[0], struct btrfs_file_extent_item);
 118         btrfs_set_file_extent_generation(ei, trans->transid);
 119         btrfs_set_file_extent_type(ei,
 120                                    BTRFS_FILE_EXTENT_INLINE);
 121         ptr = btrfs_file_extent_inline_start(ei);
 122
 123         kaddr = kmap_atomic(page, KM_USER0);
 124         btrfs_memcpy(root, path->nodes[0]->b_data,
 125                      ptr, kaddr + page_offset, size);
 126         kunmap_atomic(kaddr, KM_USER0);
 127         btrfs_mark_buffer_dirty(path->nodes[0]);
 128 fail:
 129         btrfs_free_path(path);
 130         return err;
 131 }
 132
 133 static int dirty_and_release_pages(struct btrfs_trans_handle *trans,
 134                                    struct btrfs_root *root,
 135                                    struct file *file,
 136                                    struct page **pages,
 137                                    size_t num_pages,
 138                                    loff_t pos,
 139                                    size_t write_bytes)
 140 {
 141         int err = 0;
 142         int i;
 143         struct inode *inode = file->f_path.dentry->d_inode;
 144         struct extent_map *em;
 145         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
 146         u64 hint_block;
 147         u64 num_blocks;
 148         u64 start_pos;
 149         u64 end_of_last_block;
 150         u64 end_pos = pos + write_bytes;
 151         loff_t isize = i_size_read(inode);
 152
 153         em = alloc_extent_map(GFP_NOFS);
 154         if (!em)
 155                 return -ENOMEM;
 156
 157         em->bdev = inode->i_sb->s_bdev;
 158
 159         start_pos = pos & ~((u64)root->blocksize - 1);
 160         num_blocks = (write_bytes + pos - start_pos + root->blocksize - 1) >>
 161                         inode->i_blkbits;
 162
 163         end_of_last_block = start_pos + (num_blocks << inode->i_blkbits) - 1;
 164         lock_extent(em_tree, start_pos, end_of_last_block, GFP_NOFS);
 165         mutex_lock(&root->fs_info->fs_mutex);
 166         trans = btrfs_start_transaction(root, 1);
 167         if (!trans) {
 168                 err = -ENOMEM;
 169                 goto out_unlock;
 170         }
 171         btrfs_set_trans_block_group(trans, inode);
 172         inode->i_blocks += num_blocks << 3;
 173         hint_block = 0;
 174
 175         if ((end_of_last_block & 4095) == 0) {
 176                 printk("strange end of last %Lu %lu %Lu\n", start_pos, write_bytes, end_of_last_block);
 177         }
 178         set_extent_uptodate(em_tree, start_pos, end_of_last_block, GFP_NOFS);
 179
 180         /* FIXME...EIEIO, ENOSPC and more */
 181
 182         /* insert any holes we need to create */
 183         if (inode->i_size < start_pos) {
 184                 u64 last_pos_in_file;
 185                 u64 hole_size;
 186                 u64 mask = root->blocksize - 1;
 187                 last_pos_in_file = (isize + mask) & ~mask;
 188                 hole_size = (start_pos - last_pos_in_file + mask) & ~mask;
 189
 190                 if (last_pos_in_file < start_pos) {
 191                         err = btrfs_drop_extents(trans, root, inode,
 192                                                  last_pos_in_file,
 193                                                  last_pos_in_file + hole_size,
 194                                                  &hint_block);
 195                         if (err)
 196                                 goto failed;
 197
 198                         hole_size >>= inode->i_blkbits;
 199                         err = btrfs_insert_file_extent(trans, root,
 200                                                        inode->i_ino,
 201                                                        last_pos_in_file,
 202                                                        0, 0, hole_size);
 203                 }
 204                 if (err)
 205                         goto failed;
 206         }
 207
 208         /*
 209          * either allocate an extent for the new bytes or setup the key
 210          * to show we are doing inline data in the extent
 211          */
 212         if (isize >= PAGE_CACHE_SIZE || pos + write_bytes < inode->i_size ||
 213             pos + write_bytes - start_pos > BTRFS_MAX_INLINE_DATA_SIZE(root)) {
 214                 u64 last_end;
 215                 for (i = 0; i < num_pages; i++) {
 216                         struct page *p = pages[i];
 217                         SetPageUptodate(p);
 218                         set_page_dirty(p);
 219                 }
 220                 last_end = pages[num_pages -1]->index << PAGE_CACHE_SHIFT;
 221                 last_end += PAGE_CACHE_SIZE - 1;
 222                 set_extent_delalloc(em_tree, start_pos, end_of_last_block,
 223                                  GFP_NOFS);
 224         } else {
 225                 struct page *p = pages[0];
 226                 /* step one, delete the existing extents in this range */
 227                 /* FIXME blocksize != pagesize */
 228                 err = btrfs_drop_extents(trans, root, inode, start_pos,
 229                          (pos + write_bytes + root->blocksize -1) &
 230                          ~((u64)root->blocksize - 1), &hint_block);
 231                 if (err)
 232                         goto failed;
 233
 234                 err = insert_inline_extent(trans, root, inode, start_pos,
 235                                            end_pos - start_pos, p, 0);
 236                 BUG_ON(err);
 237                 em->start = start_pos;
 238                 em->end = end_pos;
 239                 em->block_start = EXTENT_MAP_INLINE;
 240                 em->block_end = EXTENT_MAP_INLINE;
 241                 add_extent_mapping(em_tree, em);
 242         }
 243         if (end_pos > isize) {
 244                 i_size_write(inode, end_pos);
 245                 btrfs_update_inode(trans, root, inode);
 246         }
 247 failed:
 248         err = btrfs_end_transaction(trans, root);
 249 out_unlock:
 250         mutex_unlock(&root->fs_info->fs_mutex);
 251         unlock_extent(em_tree, start_pos, end_of_last_block, GFP_NOFS);
 252         free_extent_map(em);
 253         return err;
 254 }
 255
 256 int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end)
 257 {
 258         struct extent_map *em;
 259         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
 260
 261         while(1) {
 262                 em = lookup_extent_mapping(em_tree, start, end);
 263                 if (!em)
 264                         break;
 265                 remove_extent_mapping(em_tree, em);
 266                 /* once for us */
 267                 free_extent_map(em);
 268                 /* once for the tree*/
 269                 free_extent_map(em);
 270         }
 271         return 0;
 272 }
 273
 274 /*
 275  * this is very complex, but the basic idea is to drop all extents
 276  * in the range start - end.  hint_block is filled in with a block number
 277  * that would be a good hint to the block allocator for this file.
 278  *
 279  * If an extent intersects the range but is not entirely inside the range
 280  * it is either truncated or split.  Anything entirely inside the range
 281  * is deleted from the tree.
 282  */
 283 int btrfs_drop_extents(struct btrfs_trans_handle *trans,
 284                        struct btrfs_root *root, struct inode *inode,
 285                        u64 start, u64 end, u64 *hint_block)
 286 {
 287         int ret;
 288         struct btrfs_key key;
 289         struct btrfs_leaf *leaf;
 290         int slot;
 291         struct btrfs_file_extent_item *extent;
 292         u64 extent_end = 0;
 293         int keep;
 294         struct btrfs_file_extent_item old;
 295         struct btrfs_path *path;
 296         u64 search_start = start;
 297         int bookend;
 298         int found_type;
 299         int found_extent;
 300         int found_inline;
 301         int recow;
 302
 303         btrfs_drop_extent_cache(inode, start, end - 1);
 304
 305         path = btrfs_alloc_path();
 306         if (!path)
 307                 return -ENOMEM;
 308         while(1) {
 309                 recow = 0;
 310                 btrfs_release_path(root, path);
 311                 ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
 312                                                search_start, -1);
 313                 if (ret < 0)
 314                         goto out;
 315                 if (ret > 0) {
 316                         if (path->slots[0] == 0) {
 317                                 ret = 0;
 318                                 goto out;
 319                         }
 320                         path->slots[0]--;
 321                 }
 322 next_slot:
 323                 keep = 0;
 324                 bookend = 0;
 325                 found_extent = 0;
 326                 found_inline = 0;
 327                 extent = NULL;
 328                 leaf = btrfs_buffer_leaf(path->nodes[0]);
 329                 slot = path->slots[0];
 330                 ret = 0;
 331                 btrfs_disk_key_to_cpu(&key, &leaf->items[slot].key);
 332                 if (key.offset >= end || key.objectid != inode->i_ino) {
 333                         goto out;
 334                 }
 335                 if (btrfs_key_type(&key) > BTRFS_EXTENT_DATA_KEY) {
 336                         goto out;
 337                 }
 338                 if (recow) {
 339                         search_start = key.offset;
 340                         continue;
 341                 }
 342                 if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY) {
 343                         extent = btrfs_item_ptr(leaf, slot,
 344                                                 struct btrfs_file_extent_item);
 345                         found_type = btrfs_file_extent_type(extent);
 346                         if (found_type == BTRFS_FILE_EXTENT_REG) {
 347                                 extent_end = key.offset +
 348                                         (btrfs_file_extent_num_blocks(extent) <<
 349                                          inode->i_blkbits);
 350                                 found_extent = 1;
 351                         } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
 352                                 found_inline = 1;
 353                                 extent_end = key.offset +
 354                                      btrfs_file_extent_inline_len(leaf->items +
 355                                                                   slot);
 356                         }
 357                 } else {
 358                         extent_end = search_start;
 359                 }
 360
 361                 /* we found nothing we can drop */
 362                 if ((!found_extent && !found_inline) ||
 363                     search_start >= extent_end) {
 364                         int nextret;
 365                         u32 nritems;
 366                         nritems = btrfs_header_nritems(
 367                                         btrfs_buffer_header(path->nodes[0]));
 368                         if (slot >= nritems - 1) {
 369                                 nextret = btrfs_next_leaf(root, path);
 370                                 if (nextret)
 371                                         goto out;
 372                                 recow = 1;
 373                         } else {
 374                                 path->slots[0]++;
 375                         }
 376                         goto next_slot;
 377                 }
 378
 379                 /* FIXME, there's only one inline extent allowed right now */
 380                 if (found_inline) {
 381                         u64 mask = root->blocksize - 1;
 382                         search_start = (extent_end + mask) & ~mask;
 383                 } else
 384                         search_start = extent_end;
 385
 386                 if (end < extent_end && end >= key.offset) {
 387                         if (found_extent) {
 388                                 u64 disk_blocknr =
 389                                         btrfs_file_extent_disk_blocknr(extent);
 390                                 u64 disk_num_blocks =
 391                                       btrfs_file_extent_disk_num_blocks(extent);
 392                                 memcpy(&old, extent, sizeof(old));
 393                                 if (disk_blocknr != 0) {
 394                                         ret = btrfs_inc_extent_ref(trans, root,
 395                                                  disk_blocknr, disk_num_blocks);
 396                                         BUG_ON(ret);
 397                                 }
 398                         }
 399                         WARN_ON(found_inline);
 400                         bookend = 1;
 401                 }
 402                 /* truncate existing extent */
 403                 if (start > key.offset) {
 404                         u64 new_num;
 405                         u64 old_num;
 406                         keep = 1;
 407                         WARN_ON(start & (root->blocksize - 1));
 408                         if (found_extent) {
 409                                 new_num = (start - key.offset) >>
 410                                         inode->i_blkbits;
 411                                 old_num = btrfs_file_extent_num_blocks(extent);
 412                                 *hint_block =
 413                                         btrfs_file_extent_disk_blocknr(extent);
 414                                 if (btrfs_file_extent_disk_blocknr(extent)) {
 415                                         inode->i_blocks -=
 416                                                 (old_num - new_num) << 3;
 417                                 }
 418                                 btrfs_set_file_extent_num_blocks(extent,
 419                                                                  new_num);
 420                                 btrfs_mark_buffer_dirty(path->nodes[0]);
 421                         } else {
 422                                 WARN_ON(1);
 423                         }
 424                 }
 425                 /* delete the entire extent */
 426                 if (!keep) {
 427                         u64 disk_blocknr = 0;
 428                         u64 disk_num_blocks = 0;
 429                         u64 extent_num_blocks = 0;
 430                         if (found_extent) {
 431                                 disk_blocknr =
 432                                       btrfs_file_extent_disk_blocknr(extent);
 433                                 disk_num_blocks =
 434                                       btrfs_file_extent_disk_num_blocks(extent);
 435                                 extent_num_blocks =
 436                                       btrfs_file_extent_num_blocks(extent);
 437                                 *hint_block =
 438                                         btrfs_file_extent_disk_blocknr(extent);
 439                         }
 440                         ret = btrfs_del_item(trans, root, path);
 441                         /* TODO update progress marker and return */
 442                         BUG_ON(ret);
 443                         btrfs_release_path(root, path);
 444                         extent = NULL;
 445                         if (found_extent && disk_blocknr != 0) {
 446                                 inode->i_blocks -= extent_num_blocks << 3;
 447                                 ret = btrfs_free_extent(trans, root,
 448                                                         disk_blocknr,
 449                                                         disk_num_blocks, 0);
 450                         }
 451
 452                         BUG_ON(ret);
 453                         if (!bookend && search_start >= end) {
 454                                 ret = 0;
 455                                 goto out;
 456                         }
 457                         if (!bookend)
 458                                 continue;
 459                 }
 460                 /* create bookend, splitting the extent in two */
 461                 if (bookend && found_extent) {
 462                         struct btrfs_key ins;
 463                         ins.objectid = inode->i_ino;
 464                         ins.offset = end;
 465                         ins.flags = 0;
 466                         btrfs_set_key_type(&ins, BTRFS_EXTENT_DATA_KEY);
 467                         btrfs_release_path(root, path);
 468                         ret = btrfs_insert_empty_item(trans, root, path, &ins,
 469                                                       sizeof(*extent));
 470
 471                         if (ret) {
 472                                 btrfs_print_leaf(root, btrfs_buffer_leaf(path->nodes[0]));
 473                                 printk("got %d on inserting %Lu %u %Lu start %Lu end %Lu found %Lu %Lu keep was %d\n", ret , ins.objectid, ins.flags, ins.offset, start, end, key.offset, extent_end, keep);
 474                         }
 475                         BUG_ON(ret);
 476                         extent = btrfs_item_ptr(
 477                                     btrfs_buffer_leaf(path->nodes[0]),
 478                                     path->slots[0],
 479                                     struct btrfs_file_extent_item);
 480                         btrfs_set_file_extent_disk_blocknr(extent,
 481                                     btrfs_file_extent_disk_blocknr(&old));
 482                         btrfs_set_file_extent_disk_num_blocks(extent,
 483                                     btrfs_file_extent_disk_num_blocks(&old));
 484
 485                         btrfs_set_file_extent_offset(extent,
 486                                     btrfs_file_extent_offset(&old) +
 487                                     ((end - key.offset) >> inode->i_blkbits));
 488                         WARN_ON(btrfs_file_extent_num_blocks(&old) <
 489                                 (extent_end - end) >> inode->i_blkbits);
 490                         btrfs_set_file_extent_num_blocks(extent,
 491                                     (extent_end - end) >> inode->i_blkbits);
 492
 493                         btrfs_set_file_extent_type(extent,
 494                                                    BTRFS_FILE_EXTENT_REG);
 495                         btrfs_set_file_extent_generation(extent,
 496                                     btrfs_file_extent_generation(&old));
 497                         btrfs_mark_buffer_dirty(path->nodes[0]);
 498                         if (btrfs_file_extent_disk_blocknr(&old) != 0) {
 499                                 inode->i_blocks +=
 500                                       btrfs_file_extent_num_blocks(extent) << 3;
 501                         }
 502                         ret = 0;
 503                         goto out;
 504                 }
 505         }
 506 out:
 507         btrfs_free_path(path);
 508         return ret;
 509 }
 510
 511 /*
 512  * this gets pages into the page cache and locks them down
 513  */
 514 static int prepare_pages(struct btrfs_root *root,
 515                          struct file *file,
 516                          struct page **pages,
 517                          size_t num_pages,
 518                          loff_t pos,
 519                          unsigned long first_index,
 520                          unsigned long last_index,
 521                          size_t write_bytes)
 522 {
 523         int i;
 524         unsigned long index = pos >> PAGE_CACHE_SHIFT;
 525         struct inode *inode = file->f_path.dentry->d_inode;
 526         int err = 0;
 527         u64 num_blocks;
 528         u64 start_pos;
 529
 530         start_pos = pos & ~((u64)root->blocksize - 1);
 531         num_blocks = (write_bytes + pos - start_pos + root->blocksize - 1) >>
 532                         inode->i_blkbits;
 533
 534         memset(pages, 0, num_pages * sizeof(struct page *));
 535
 536         for (i = 0; i < num_pages; i++) {
 537                 pages[i] = grab_cache_page(inode->i_mapping, index + i);
 538                 if (!pages[i]) {
 539                         err = -ENOMEM;
 540                         BUG_ON(1);
 541                 }
 542                 cancel_dirty_page(pages[i], PAGE_CACHE_SIZE);
 543                 wait_on_page_writeback(pages[i]);
 544                 if (!PagePrivate(pages[i])) {
 545                         SetPagePrivate(pages[i]);
 546                         set_page_private(pages[i], 1);
 547                         WARN_ON(!pages[i]->mapping->a_ops->invalidatepage);
 548                         page_cache_get(pages[i]);
 549                 }
 550                 WARN_ON(!PageLocked(pages[i]));
 551         }
 552         return 0;
 553 }
 554
 555 static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
 556                                 size_t count, loff_t *ppos)
 557 {
 558         loff_t pos;
 559         size_t num_written = 0;
 560         int err = 0;
 561         int ret = 0;
 562         struct inode *inode = file->f_path.dentry->d_inode;
 563         struct btrfs_root *root = BTRFS_I(inode)->root;
 564         struct page **pages = NULL;
 565         int nrptrs;
 566         struct page *pinned[2];
 567         unsigned long first_index;
 568         unsigned long last_index;
 569
 570         nrptrs = min((count + PAGE_CACHE_SIZE - 1) / PAGE_CACHE_SIZE,
 571                      PAGE_CACHE_SIZE / (sizeof(struct page *)));
 572         pinned[0] = NULL;
 573         pinned[1] = NULL;
 574         if (file->f_flags & O_DIRECT)
 575                 return -EINVAL;
 576         pos = *ppos;
 577         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
 578         current->backing_dev_info = inode->i_mapping->backing_dev_info;
 579         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
 580         if (err)
 581                 goto out;
 582         if (count == 0)
 583                 goto out;
 584         err = remove_suid(file->f_path.dentry);
 585         if (err)
 586                 goto out;
 587         file_update_time(file);
 588
 589         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
 590
 591         mutex_lock(&inode->i_mutex);
 592         first_index = pos >> PAGE_CACHE_SHIFT;
 593         last_index = (pos + count) >> PAGE_CACHE_SHIFT;
 594
 595         /*
 596          * there are lots of better ways to do this, but this code
 597          * makes sure the first and last page in the file range are
 598          * up to date and ready for cow
 599          */
 600         if ((pos & (PAGE_CACHE_SIZE - 1))) {
 601                 pinned[0] = grab_cache_page(inode->i_mapping, first_index);
 602                 if (!PageUptodate(pinned[0])) {
 603                         ret = btrfs_readpage(NULL, pinned[0]);
 604                         BUG_ON(ret);
 605                         wait_on_page_locked(pinned[0]);
 606                 } else {
 607                         unlock_page(pinned[0]);
 608                 }
 609         }
 610         if ((pos + count) & (PAGE_CACHE_SIZE - 1)) {
 611                 pinned[1] = grab_cache_page(inode->i_mapping, last_index);
 612                 if (!PageUptodate(pinned[1])) {
 613                         ret = btrfs_readpage(NULL, pinned[1]);
 614                         BUG_ON(ret);
 615                         wait_on_page_locked(pinned[1]);
 616                 } else {
 617                         unlock_page(pinned[1]);
 618                 }
 619         }
 620
 621         while(count > 0) {
 622                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
 623                 size_t write_bytes = min(count, nrptrs *
 624                                         (size_t)PAGE_CACHE_SIZE -
 625                                          offset);
 626                 size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
 627                                         PAGE_CACHE_SHIFT;
 628
 629                 WARN_ON(num_pages > nrptrs);
 630                 memset(pages, 0, sizeof(pages));
 631                 ret = prepare_pages(root, file, pages, num_pages,
 632                                     pos, first_index, last_index,
 633                                     write_bytes);
 634                 if (ret)
 635                         goto out;
 636
 637                 ret = btrfs_copy_from_user(pos, num_pages,
 638                                            write_bytes, pages, buf);
 639                 if (ret) {
 640                         btrfs_drop_pages(pages, num_pages);
 641                         goto out;
 642                 }
 643
 644                 ret = dirty_and_release_pages(NULL, root, file, pages,
 645                                               num_pages, pos, write_bytes);
 646                 btrfs_drop_pages(pages, num_pages);
 647                 if (ret)
 648                         goto out;
 649
 650                 buf += write_bytes;
 651                 count -= write_bytes;
 652                 pos += write_bytes;
 653                 num_written += write_bytes;
 654
 655                 balance_dirty_pages_ratelimited_nr(inode->i_mapping, num_pages);
 656                 btrfs_btree_balance_dirty(root);
 657                 cond_resched();
 658         }
 659         mutex_unlock(&inode->i_mutex);
 660 out:
 661         kfree(pages);
 662         if (pinned[0])
 663                 page_cache_release(pinned[0]);
 664         if (pinned[1])
 665                 page_cache_release(pinned[1]);
 666         *ppos = pos;
 667         current->backing_dev_info = NULL;
 668         return num_written ? num_written : err;
 669 }
 670
 671 static int btrfs_sync_file(struct file *file,
 672                            struct dentry *dentry, int datasync)
 673 {
 674         struct inode *inode = dentry->d_inode;
 675         struct btrfs_root *root = BTRFS_I(inode)->root;
 676         int ret = 0;
 677         struct btrfs_trans_handle *trans;
 678
 679         /*
 680          * check the transaction that last modified this inode
 681          * and see if its already been committed
 682          */
 683         mutex_lock(&root->fs_info->fs_mutex);
 684         if (!BTRFS_I(inode)->last_trans)
 685                 goto out;
 686         mutex_lock(&root->fs_info->trans_mutex);
 687         if (BTRFS_I(inode)->last_trans <=
 688             root->fs_info->last_trans_committed) {
 689                 BTRFS_I(inode)->last_trans = 0;
 690                 mutex_unlock(&root->fs_info->trans_mutex);
 691                 goto out;
 692         }
 693         mutex_unlock(&root->fs_info->trans_mutex);
 694
 695         /*
 696          * ok we haven't committed the transaction yet, lets do a commit
 697          */
 698         trans = btrfs_start_transaction(root, 1);
 699         if (!trans) {
 700                 ret = -ENOMEM;
 701                 goto out;
 702         }
 703         ret = btrfs_commit_transaction(trans, root);
 704 out:
 705         mutex_unlock(&root->fs_info->fs_mutex);
 706         return ret > 0 ? EIO : ret;
 707 }
 708
 709 static struct vm_operations_struct btrfs_file_vm_ops = {
 710 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
 711         .nopage         = filemap_nopage,
 712         .populate       = filemap_populate,
 713 #else
 714         .fault          = filemap_fault,
 715 #endif
 716         .page_mkwrite   = btrfs_page_mkwrite,
 717 };
 718
 719 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
 720 {
 721         vma->vm_ops = &btrfs_file_vm_ops;
 722         file_accessed(filp);
 723         return 0;
 724 }
 725
 726 struct file_operations btrfs_file_operations = {
 727         .llseek         = generic_file_llseek,
 728         .read           = do_sync_read,
 729         .aio_read       = generic_file_aio_read,
 730         .write          = btrfs_file_write,
 731         .mmap           = btrfs_file_mmap,
 732         .open           = generic_file_open,
 733         .ioctl          = btrfs_ioctl,
 734         .fsync          = btrfs_sync_file,
 735 #ifdef CONFIG_COMPAT
 736         .compat_ioctl   = btrfs_compat_ioctl,
 737 #endif
 738 };
 739