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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 "ordered-data.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 noinline insert_inline_extent(struct btrfs_trans_handle *trans,
  85                                 struct btrfs_root *root, struct inode *inode,
  86                                 u64 offset, size_t size,
  87                                 struct page **pages, size_t page_offset,
  88                                 int num_pages)
  89 {
  90         struct btrfs_key key;
  91         struct btrfs_path *path;
  92         struct extent_buffer *leaf;
  93         char *kaddr;
  94         unsigned long ptr;
  95         struct btrfs_file_extent_item *ei;
  96         struct page *page;
  97         u32 datasize;
  98         int err = 0;
  99         int ret;
 100         int i;
 101         ssize_t cur_size;
 102
 103         path = btrfs_alloc_path();
 104         if (!path)
 105                 return -ENOMEM;
 106
 107         btrfs_set_trans_block_group(trans, inode);
 108
 109         key.objectid = inode->i_ino;
 110         key.offset = offset;
 111         btrfs_set_key_type(&key, BTRFS_EXTENT_DATA_KEY);
 112
 113         ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
 114         if (ret < 0) {
 115                 err = ret;
 116                 goto fail;
 117         }
 118         if (ret == 1) {
 119                 struct btrfs_key found_key;
 120
 121                 if (path->slots[0] == 0)
 122                         goto insert;
 123
 124                 path->slots[0]--;
 125                 leaf = path->nodes[0];
 126                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 127
 128                 if (found_key.objectid != inode->i_ino)
 129                         goto insert;
 130
 131                 if (found_key.type != BTRFS_EXTENT_DATA_KEY)
 132                         goto insert;
 133                 ei = btrfs_item_ptr(leaf, path->slots[0],
 134                                     struct btrfs_file_extent_item);
 135
 136                 if (btrfs_file_extent_type(leaf, ei) !=
 137                     BTRFS_FILE_EXTENT_INLINE) {
 138                         goto insert;
 139                 }
 140                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 141                 ret = 0;
 142         }
 143         if (ret == 0) {
 144                 u32 found_size;
 145                 u64 found_end;
 146
 147                 leaf = path->nodes[0];
 148                 ei = btrfs_item_ptr(leaf, path->slots[0],
 149                                     struct btrfs_file_extent_item);
 150
 151                 if (btrfs_file_extent_type(leaf, ei) !=
 152                     BTRFS_FILE_EXTENT_INLINE) {
 153                         err = ret;
 154                         btrfs_print_leaf(root, leaf);
 155                         printk("found wasn't inline offset %Lu inode %lu\n",
 156                                offset, inode->i_ino);
 157                         goto fail;
 158                 }
 159                 found_size = btrfs_file_extent_inline_len(leaf,
 160                                           btrfs_item_nr(leaf, path->slots[0]));
 161                 found_end = key.offset + found_size;
 162
 163                 if (found_end < offset + size) {
 164                         btrfs_release_path(root, path);
 165                         ret = btrfs_search_slot(trans, root, &key, path,
 166                                                 offset + size - found_end, 1);
 167                         BUG_ON(ret != 0);
 168
 169                         ret = btrfs_extend_item(trans, root, path,
 170                                                 offset + size - found_end);
 171                         if (ret) {
 172                                 err = ret;
 173                                 goto fail;
 174                         }
 175                         leaf = path->nodes[0];
 176                         ei = btrfs_item_ptr(leaf, path->slots[0],
 177                                             struct btrfs_file_extent_item);
 178                 }
 179                 if (found_end < offset) {
 180                         ptr = btrfs_file_extent_inline_start(ei) + found_size;
 181                         memset_extent_buffer(leaf, 0, ptr, offset - found_end);
 182                 }
 183         } else {
 184 insert:
 185                 btrfs_release_path(root, path);
 186                 datasize = offset + size - key.offset;
 187                 datasize = btrfs_file_extent_calc_inline_size(datasize);
 188                 ret = btrfs_insert_empty_item(trans, root, path, &key,
 189                                               datasize);
 190                 if (ret) {
 191                         err = ret;
 192                         printk("got bad ret %d\n", ret);
 193                         goto fail;
 194                 }
 195                 leaf = path->nodes[0];
 196                 ei = btrfs_item_ptr(leaf, path->slots[0],
 197                                     struct btrfs_file_extent_item);
 198                 btrfs_set_file_extent_generation(leaf, ei, trans->transid);
 199                 btrfs_set_file_extent_type(leaf, ei, BTRFS_FILE_EXTENT_INLINE);
 200         }
 201         ptr = btrfs_file_extent_inline_start(ei) + offset - key.offset;
 202
 203         cur_size = size;
 204         i = 0;
 205         while (size > 0) {
 206                 page = pages[i];
 207                 kaddr = kmap_atomic(page, KM_USER0);
 208                 cur_size = min_t(size_t, PAGE_CACHE_SIZE - page_offset, size);
 209                 write_extent_buffer(leaf, kaddr + page_offset, ptr, cur_size);
 210                 kunmap_atomic(kaddr, KM_USER0);
 211                 page_offset = 0;
 212                 ptr += cur_size;
 213                 size -= cur_size;
 214                 if (i >= num_pages) {
 215                         printk("i %d num_pages %d\n", i, num_pages);
 216                 }
 217                 i++;
 218         }
 219         btrfs_mark_buffer_dirty(leaf);
 220 fail:
 221         btrfs_free_path(path);
 222         return err;
 223 }
 224
 225 static int noinline dirty_and_release_pages(struct btrfs_trans_handle *trans,
 226                                    struct btrfs_root *root,
 227                                    struct file *file,
 228                                    struct page **pages,
 229                                    size_t num_pages,
 230                                    loff_t pos,
 231                                    size_t write_bytes)
 232 {
 233         int err = 0;
 234         int i;
 235         struct inode *inode = fdentry(file)->d_inode;
 236         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 237         u64 hint_byte;
 238         u64 num_bytes;
 239         u64 start_pos;
 240         u64 end_of_last_block;
 241         u64 end_pos = pos + write_bytes;
 242         u64 inline_size;
 243         loff_t isize = i_size_read(inode);
 244
 245         start_pos = pos & ~((u64)root->sectorsize - 1);
 246         num_bytes = (write_bytes + pos - start_pos +
 247                     root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
 248
 249         end_of_last_block = start_pos + num_bytes - 1;
 250
 251         lock_extent(io_tree, start_pos, end_of_last_block, GFP_NOFS);
 252         mutex_lock(&root->fs_info->fs_mutex);
 253         trans = btrfs_start_transaction(root, 1);
 254         if (!trans) {
 255                 err = -ENOMEM;
 256                 goto out_unlock;
 257         }
 258         btrfs_set_trans_block_group(trans, inode);
 259         inode->i_blocks += num_bytes >> 9;
 260         hint_byte = 0;
 261
 262         if ((end_of_last_block & 4095) == 0) {
 263                 printk("strange end of last %Lu %zu %Lu\n", start_pos, write_bytes, end_of_last_block);
 264         }
 265         set_extent_uptodate(io_tree, start_pos, end_of_last_block, GFP_NOFS);
 266
 267         /* FIXME...EIEIO, ENOSPC and more */
 268
 269         /* insert any holes we need to create */
 270         if (inode->i_size < start_pos) {
 271                 u64 last_pos_in_file;
 272                 u64 hole_size;
 273                 u64 mask = root->sectorsize - 1;
 274                 last_pos_in_file = (isize + mask) & ~mask;
 275                 hole_size = (end_pos - last_pos_in_file + mask) & ~mask;
 276
 277                 if (last_pos_in_file < start_pos) {
 278                         err = btrfs_drop_extents(trans, root, inode,
 279                                                  last_pos_in_file,
 280                                                  last_pos_in_file + hole_size,
 281                                                  last_pos_in_file,
 282                                                  &hint_byte);
 283                         if (err)
 284                                 goto failed;
 285
 286                         err = btrfs_insert_file_extent(trans, root,
 287                                                        inode->i_ino,
 288                                                        last_pos_in_file,
 289                                                        0, 0, hole_size);
 290                         btrfs_drop_extent_cache(inode, last_pos_in_file,
 291                                         last_pos_in_file + hole_size -1);
 292                         btrfs_check_file(root, inode);
 293                 }
 294                 if (err)
 295                         goto failed;
 296         }
 297
 298         /*
 299          * either allocate an extent for the new bytes or setup the key
 300          * to show we are doing inline data in the extent
 301          */
 302         inline_size = end_pos;
 303         if (isize >= BTRFS_MAX_INLINE_DATA_SIZE(root) ||
 304             inline_size > 8192 ||
 305             inline_size >= BTRFS_MAX_INLINE_DATA_SIZE(root)) {
 306                 u64 last_end;
 307                 u64 existing_delalloc = 0;
 308
 309                 for (i = 0; i < num_pages; i++) {
 310                         struct page *p = pages[i];
 311                         SetPageUptodate(p);
 312                         set_page_dirty(p);
 313                 }
 314                 last_end = (u64)(pages[num_pages -1]->index) <<
 315                                 PAGE_CACHE_SHIFT;
 316                 last_end += PAGE_CACHE_SIZE - 1;
 317                 if (start_pos < isize) {
 318                         u64 delalloc_start = start_pos;
 319                         existing_delalloc = count_range_bits(io_tree,
 320                                              &delalloc_start,
 321                                              end_of_last_block, (u64)-1,
 322                                              EXTENT_DELALLOC);
 323                 }
 324                 set_extent_delalloc(io_tree, start_pos, end_of_last_block,
 325                                  GFP_NOFS);
 326                 spin_lock(&root->fs_info->delalloc_lock);
 327                 root->fs_info->delalloc_bytes += (end_of_last_block + 1 -
 328                                           start_pos) - existing_delalloc;
 329                 spin_unlock(&root->fs_info->delalloc_lock);
 330                 btrfs_add_ordered_inode(inode);
 331         } else {
 332                 u64 aligned_end;
 333                 /* step one, delete the existing extents in this range */
 334                 aligned_end = (pos + write_bytes + root->sectorsize - 1) &
 335                         ~((u64)root->sectorsize - 1);
 336                 err = btrfs_drop_extents(trans, root, inode, start_pos,
 337                                          aligned_end, aligned_end, &hint_byte);
 338                 if (err)
 339                         goto failed;
 340                 if (isize > inline_size)
 341                         inline_size = min_t(u64, isize, aligned_end);
 342                 inline_size -= start_pos;
 343                 err = insert_inline_extent(trans, root, inode, start_pos,
 344                                            inline_size, pages, 0, num_pages);
 345                 btrfs_drop_extent_cache(inode, start_pos, aligned_end - 1);
 346                 BUG_ON(err);
 347         }
 348         if (end_pos > isize) {
 349                 i_size_write(inode, end_pos);
 350                 btrfs_update_inode(trans, root, inode);
 351         }
 352 failed:
 353         err = btrfs_end_transaction(trans, root);
 354 out_unlock:
 355         mutex_unlock(&root->fs_info->fs_mutex);
 356         unlock_extent(io_tree, start_pos, end_of_last_block, GFP_NOFS);
 357         return err;
 358 }
 359
 360 int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end)
 361 {
 362         struct extent_map *em;
 363         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
 364
 365         while(1) {
 366                 spin_lock(&em_tree->lock);
 367                 em = lookup_extent_mapping(em_tree, start, end);
 368                 if (!em) {
 369                         spin_unlock(&em_tree->lock);
 370                         break;
 371                 }
 372                 remove_extent_mapping(em_tree, em);
 373                 spin_unlock(&em_tree->lock);
 374
 375                 /* once for us */
 376                 free_extent_map(em);
 377                 /* once for the tree*/
 378                 free_extent_map(em);
 379         }
 380         return 0;
 381 }
 382
 383 int btrfs_check_file(struct btrfs_root *root, struct inode *inode)
 384 {
 385         return 0;
 386 #if 0
 387         struct btrfs_path *path;
 388         struct btrfs_key found_key;
 389         struct extent_buffer *leaf;
 390         struct btrfs_file_extent_item *extent;
 391         u64 last_offset = 0;
 392         int nritems;
 393         int slot;
 394         int found_type;
 395         int ret;
 396         int err = 0;
 397         u64 extent_end = 0;
 398
 399         path = btrfs_alloc_path();
 400         ret = btrfs_lookup_file_extent(NULL, root, path, inode->i_ino,
 401                                        last_offset, 0);
 402         while(1) {
 403                 nritems = btrfs_header_nritems(path->nodes[0]);
 404                 if (path->slots[0] >= nritems) {
 405                         ret = btrfs_next_leaf(root, path);
 406                         if (ret)
 407                                 goto out;
 408                         nritems = btrfs_header_nritems(path->nodes[0]);
 409                 }
 410                 slot = path->slots[0];
 411                 leaf = path->nodes[0];
 412                 btrfs_item_key_to_cpu(leaf, &found_key, slot);
 413                 if (found_key.objectid != inode->i_ino)
 414                         break;
 415                 if (found_key.type != BTRFS_EXTENT_DATA_KEY)
 416                         goto out;
 417
 418                 if (found_key.offset != last_offset) {
 419                         WARN_ON(1);
 420                         btrfs_print_leaf(root, leaf);
 421                         printk("inode %lu found offset %Lu expected %Lu\n",
 422                                inode->i_ino, found_key.offset, last_offset);
 423                         err = 1;
 424                         goto out;
 425                 }
 426                 extent = btrfs_item_ptr(leaf, slot,
 427                                         struct btrfs_file_extent_item);
 428                 found_type = btrfs_file_extent_type(leaf, extent);
 429                 if (found_type == BTRFS_FILE_EXTENT_REG) {
 430                         extent_end = found_key.offset +
 431                              btrfs_file_extent_num_bytes(leaf, extent);
 432                 } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
 433                         struct btrfs_item *item;
 434                         item = btrfs_item_nr(leaf, slot);
 435                         extent_end = found_key.offset +
 436                              btrfs_file_extent_inline_len(leaf, item);
 437                         extent_end = (extent_end + root->sectorsize - 1) &
 438                                 ~((u64)root->sectorsize -1 );
 439                 }
 440                 last_offset = extent_end;
 441                 path->slots[0]++;
 442         }
 443         if (last_offset < inode->i_size) {
 444                 WARN_ON(1);
 445                 btrfs_print_leaf(root, leaf);
 446                 printk("inode %lu found offset %Lu size %Lu\n", inode->i_ino,
 447                        last_offset, inode->i_size);
 448                 err = 1;
 449
 450         }
 451 out:
 452         btrfs_free_path(path);
 453         return err;
 454 #endif
 455 }
 456
 457 /*
 458  * this is very complex, but the basic idea is to drop all extents
 459  * in the range start - end.  hint_block is filled in with a block number
 460  * that would be a good hint to the block allocator for this file.
 461  *
 462  * If an extent intersects the range but is not entirely inside the range
 463  * it is either truncated or split.  Anything entirely inside the range
 464  * is deleted from the tree.
 465  */
 466 int btrfs_drop_extents(struct btrfs_trans_handle *trans,
 467                        struct btrfs_root *root, struct inode *inode,
 468                        u64 start, u64 end, u64 inline_limit, u64 *hint_byte)
 469 {
 470         u64 extent_end = 0;
 471         u64 search_start = start;
 472         struct extent_buffer *leaf;
 473         struct btrfs_file_extent_item *extent;
 474         struct btrfs_path *path;
 475         struct btrfs_key key;
 476         struct btrfs_file_extent_item old;
 477         int keep;
 478         int slot;
 479         int bookend;
 480         int found_type;
 481         int found_extent;
 482         int found_inline;
 483         int recow;
 484         int ret;
 485
 486         btrfs_drop_extent_cache(inode, start, end - 1);
 487
 488         path = btrfs_alloc_path();
 489         if (!path)
 490                 return -ENOMEM;
 491         while(1) {
 492                 recow = 0;
 493                 btrfs_release_path(root, path);
 494                 ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
 495                                                search_start, -1);
 496                 if (ret < 0)
 497                         goto out;
 498                 if (ret > 0) {
 499                         if (path->slots[0] == 0) {
 500                                 ret = 0;
 501                                 goto out;
 502                         }
 503                         path->slots[0]--;
 504                 }
 505 next_slot:
 506                 keep = 0;
 507                 bookend = 0;
 508                 found_extent = 0;
 509                 found_inline = 0;
 510                 extent = NULL;
 511                 leaf = path->nodes[0];
 512                 slot = path->slots[0];
 513                 ret = 0;
 514                 btrfs_item_key_to_cpu(leaf, &key, slot);
 515
 516                 if (key.offset >= end || key.objectid != inode->i_ino) {
 517                         goto out;
 518                 }
 519                 if (btrfs_key_type(&key) > BTRFS_EXTENT_DATA_KEY) {
 520                         goto out;
 521                 }
 522                 if (recow) {
 523                         search_start = key.offset;
 524                         continue;
 525                 }
 526                 if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY) {
 527                         extent = btrfs_item_ptr(leaf, slot,
 528                                                 struct btrfs_file_extent_item);
 529                         found_type = btrfs_file_extent_type(leaf, extent);
 530                         if (found_type == BTRFS_FILE_EXTENT_REG) {
 531                                 extent_end =
 532                                      btrfs_file_extent_disk_bytenr(leaf,
 533                                                                    extent);
 534                                 if (extent_end)
 535                                         *hint_byte = extent_end;
 536
 537                                 extent_end = key.offset +
 538                                      btrfs_file_extent_num_bytes(leaf, extent);
 539                                 found_extent = 1;
 540                         } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
 541                                 struct btrfs_item *item;
 542                                 item = btrfs_item_nr(leaf, slot);
 543                                 found_inline = 1;
 544                                 extent_end = key.offset +
 545                                      btrfs_file_extent_inline_len(leaf, item);
 546                         }
 547                 } else {
 548                         extent_end = search_start;
 549                 }
 550
 551                 /* we found nothing we can drop */
 552                 if ((!found_extent && !found_inline) ||
 553                     search_start >= extent_end) {
 554                         int nextret;
 555                         u32 nritems;
 556                         nritems = btrfs_header_nritems(leaf);
 557                         if (slot >= nritems - 1) {
 558                                 nextret = btrfs_next_leaf(root, path);
 559                                 if (nextret)
 560                                         goto out;
 561                                 recow = 1;
 562                         } else {
 563                                 path->slots[0]++;
 564                         }
 565                         goto next_slot;
 566                 }
 567
 568                 if (found_inline) {
 569                         u64 mask = root->sectorsize - 1;
 570                         search_start = (extent_end + mask) & ~mask;
 571                 } else
 572                         search_start = extent_end;
 573                 if (end <= extent_end && start >= key.offset && found_inline) {
 574                         *hint_byte = EXTENT_MAP_INLINE;
 575                         continue;
 576                 }
 577                 if (end < extent_end && end >= key.offset) {
 578                         if (found_extent) {
 579                                 u64 disk_bytenr =
 580                                     btrfs_file_extent_disk_bytenr(leaf, extent);
 581                                 u64 disk_num_bytes =
 582                                     btrfs_file_extent_disk_num_bytes(leaf,
 583                                                                       extent);
 584                                 read_extent_buffer(leaf, &old,
 585                                                    (unsigned long)extent,
 586                                                    sizeof(old));
 587                                 if (disk_bytenr != 0) {
 588                                         ret = btrfs_inc_extent_ref(trans, root,
 589                                                  disk_bytenr, disk_num_bytes,
 590                                                  root->root_key.objectid,
 591                                                  trans->transid,
 592                                                  key.objectid, end);
 593                                         BUG_ON(ret);
 594                                 }
 595                         }
 596                         bookend = 1;
 597                         if (found_inline && start <= key.offset &&
 598                             inline_limit < extent_end)
 599                                 keep = 1;
 600                 }
 601                 /* truncate existing extent */
 602                 if (start > key.offset) {
 603                         u64 new_num;
 604                         u64 old_num;
 605                         keep = 1;
 606                         WARN_ON(start & (root->sectorsize - 1));
 607                         if (found_extent) {
 608                                 new_num = start - key.offset;
 609                                 old_num = btrfs_file_extent_num_bytes(leaf,
 610                                                                       extent);
 611                                 *hint_byte =
 612                                         btrfs_file_extent_disk_bytenr(leaf,
 613                                                                       extent);
 614                                 if (btrfs_file_extent_disk_bytenr(leaf,
 615                                                                   extent)) {
 616                                         inode->i_blocks -=
 617                                                 (old_num - new_num) >> 9;
 618                                 }
 619                                 btrfs_set_file_extent_num_bytes(leaf, extent,
 620                                                                 new_num);
 621                                 btrfs_mark_buffer_dirty(leaf);
 622                         } else if (key.offset < inline_limit &&
 623                                    (end > extent_end) &&
 624                                    (inline_limit < extent_end)) {
 625                                 u32 new_size;
 626                                 new_size = btrfs_file_extent_calc_inline_size(
 627                                                    inline_limit - key.offset);
 628                                 btrfs_truncate_item(trans, root, path,
 629                                                     new_size, 1);
 630                         }
 631                 }
 632                 /* delete the entire extent */
 633                 if (!keep) {
 634                         u64 disk_bytenr = 0;
 635                         u64 disk_num_bytes = 0;
 636                         u64 extent_num_bytes = 0;
 637                         u64 root_gen;
 638                         u64 root_owner;
 639
 640                         root_gen = btrfs_header_generation(leaf);
 641                         root_owner = btrfs_header_owner(leaf);
 642                         if (found_extent) {
 643                                 disk_bytenr =
 644                                       btrfs_file_extent_disk_bytenr(leaf,
 645                                                                      extent);
 646                                 disk_num_bytes =
 647                                       btrfs_file_extent_disk_num_bytes(leaf,
 648                                                                        extent);
 649                                 extent_num_bytes =
 650                                       btrfs_file_extent_num_bytes(leaf, extent);
 651                                 *hint_byte =
 652                                         btrfs_file_extent_disk_bytenr(leaf,
 653                                                                       extent);
 654                         }
 655                         ret = btrfs_del_item(trans, root, path);
 656                         /* TODO update progress marker and return */
 657                         BUG_ON(ret);
 658                         btrfs_release_path(root, path);
 659                         extent = NULL;
 660                         if (found_extent && disk_bytenr != 0) {
 661                                 inode->i_blocks -= extent_num_bytes >> 9;
 662                                 ret = btrfs_free_extent(trans, root,
 663                                                 disk_bytenr,
 664                                                 disk_num_bytes,
 665                                                 root_owner,
 666                                                 root_gen, inode->i_ino,
 667                                                 key.offset, 0);
 668                         }
 669
 670                         BUG_ON(ret);
 671                         if (!bookend && search_start >= end) {
 672                                 ret = 0;
 673                                 goto out;
 674                         }
 675                         if (!bookend)
 676                                 continue;
 677                 }
 678                 if (bookend && found_inline && start <= key.offset &&
 679                     inline_limit < extent_end && key.offset <= inline_limit) {
 680                         u32 new_size;
 681                         new_size = btrfs_file_extent_calc_inline_size(
 682                                                    extent_end - inline_limit);
 683                         btrfs_truncate_item(trans, root, path, new_size, 0);
 684                 }
 685                 /* create bookend, splitting the extent in two */
 686                 if (bookend && found_extent) {
 687                         struct btrfs_key ins;
 688                         ins.objectid = inode->i_ino;
 689                         ins.offset = end;
 690                         btrfs_set_key_type(&ins, BTRFS_EXTENT_DATA_KEY);
 691                         btrfs_release_path(root, path);
 692                         ret = btrfs_insert_empty_item(trans, root, path, &ins,
 693                                                       sizeof(*extent));
 694
 695                         leaf = path->nodes[0];
 696                         if (ret) {
 697                                 btrfs_print_leaf(root, leaf);
 698                                 printk("got %d on inserting %Lu %u %Lu start %Lu end %Lu found %Lu %Lu keep was %d\n", ret , ins.objectid, ins.type, ins.offset, start, end, key.offset, extent_end, keep);
 699                         }
 700                         BUG_ON(ret);
 701                         extent = btrfs_item_ptr(leaf, path->slots[0],
 702                                                 struct btrfs_file_extent_item);
 703                         write_extent_buffer(leaf, &old,
 704                                             (unsigned long)extent, sizeof(old));
 705
 706                         btrfs_set_file_extent_offset(leaf, extent,
 707                                     le64_to_cpu(old.offset) + end - key.offset);
 708                         WARN_ON(le64_to_cpu(old.num_bytes) <
 709                                 (extent_end - end));
 710                         btrfs_set_file_extent_num_bytes(leaf, extent,
 711                                                         extent_end - end);
 712                         btrfs_set_file_extent_type(leaf, extent,
 713                                                    BTRFS_FILE_EXTENT_REG);
 714
 715                         btrfs_mark_buffer_dirty(path->nodes[0]);
 716                         if (le64_to_cpu(old.disk_bytenr) != 0) {
 717                                 inode->i_blocks +=
 718                                       btrfs_file_extent_num_bytes(leaf,
 719                                                                   extent) >> 9;
 720                         }
 721                         ret = 0;
 722                         goto out;
 723                 }
 724         }
 725 out:
 726         btrfs_free_path(path);
 727         return ret;
 728 }
 729
 730 /*
 731  * this gets pages into the page cache and locks them down
 732  */
 733 static int prepare_pages(struct btrfs_root *root, struct file *file,
 734                          struct page **pages, size_t num_pages,
 735                          loff_t pos, unsigned long first_index,
 736                          unsigned long last_index, size_t write_bytes)
 737 {
 738         int i;
 739         unsigned long index = pos >> PAGE_CACHE_SHIFT;
 740         struct inode *inode = fdentry(file)->d_inode;
 741         int err = 0;
 742         u64 start_pos;
 743
 744         start_pos = pos & ~((u64)root->sectorsize - 1);
 745
 746         memset(pages, 0, num_pages * sizeof(struct page *));
 747
 748         for (i = 0; i < num_pages; i++) {
 749                 pages[i] = grab_cache_page(inode->i_mapping, index + i);
 750                 if (!pages[i]) {
 751                         err = -ENOMEM;
 752                         BUG_ON(1);
 753                 }
 754 #if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,18)
 755                 ClearPageDirty(pages[i]);
 756 #else
 757                 cancel_dirty_page(pages[i], PAGE_CACHE_SIZE);
 758 #endif
 759                 wait_on_page_writeback(pages[i]);
 760                 set_page_extent_mapped(pages[i]);
 761                 WARN_ON(!PageLocked(pages[i]));
 762         }
 763         return 0;
 764 }
 765
 766 static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
 767                                 size_t count, loff_t *ppos)
 768 {
 769         loff_t pos;
 770         loff_t start_pos;
 771         ssize_t num_written = 0;
 772         ssize_t err = 0;
 773         int ret = 0;
 774         struct inode *inode = fdentry(file)->d_inode;
 775         struct btrfs_root *root = BTRFS_I(inode)->root;
 776         struct page **pages = NULL;
 777         int nrptrs;
 778         struct page *pinned[2];
 779         unsigned long first_index;
 780         unsigned long last_index;
 781
 782         nrptrs = min((count + PAGE_CACHE_SIZE - 1) / PAGE_CACHE_SIZE,
 783                      PAGE_CACHE_SIZE / (sizeof(struct page *)));
 784         pinned[0] = NULL;
 785         pinned[1] = NULL;
 786         if (file->f_flags & O_DIRECT)
 787                 return -EINVAL;
 788
 789         pos = *ppos;
 790         start_pos = pos;
 791
 792         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
 793         current->backing_dev_info = inode->i_mapping->backing_dev_info;
 794         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
 795         if (err)
 796                 goto out_nolock;
 797         if (count == 0)
 798                 goto out_nolock;
 799         err = remove_suid(fdentry(file));
 800         if (err)
 801                 goto out_nolock;
 802         file_update_time(file);
 803
 804         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
 805
 806         mutex_lock(&inode->i_mutex);
 807         first_index = pos >> PAGE_CACHE_SHIFT;
 808         last_index = (pos + count) >> PAGE_CACHE_SHIFT;
 809
 810         /*
 811          * there are lots of better ways to do this, but this code
 812          * makes sure the first and last page in the file range are
 813          * up to date and ready for cow
 814          */
 815         if ((pos & (PAGE_CACHE_SIZE - 1))) {
 816                 pinned[0] = grab_cache_page(inode->i_mapping, first_index);
 817                 if (!PageUptodate(pinned[0])) {
 818                         ret = btrfs_readpage(NULL, pinned[0]);
 819                         BUG_ON(ret);
 820                         wait_on_page_locked(pinned[0]);
 821                 } else {
 822                         unlock_page(pinned[0]);
 823                 }
 824         }
 825         if ((pos + count) & (PAGE_CACHE_SIZE - 1)) {
 826                 pinned[1] = grab_cache_page(inode->i_mapping, last_index);
 827                 if (!PageUptodate(pinned[1])) {
 828                         ret = btrfs_readpage(NULL, pinned[1]);
 829                         BUG_ON(ret);
 830                         wait_on_page_locked(pinned[1]);
 831                 } else {
 832                         unlock_page(pinned[1]);
 833                 }
 834         }
 835
 836         while(count > 0) {
 837                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
 838                 size_t write_bytes = min(count, nrptrs *
 839                                         (size_t)PAGE_CACHE_SIZE -
 840                                          offset);
 841                 size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
 842                                         PAGE_CACHE_SHIFT;
 843
 844                 WARN_ON(num_pages > nrptrs);
 845                 memset(pages, 0, sizeof(pages));
 846
 847                 mutex_lock(&root->fs_info->fs_mutex);
 848                 ret = btrfs_check_free_space(root, write_bytes, 0);
 849                 mutex_unlock(&root->fs_info->fs_mutex);
 850                 if (ret)
 851                         goto out;
 852
 853                 ret = prepare_pages(root, file, pages, num_pages,
 854                                     pos, first_index, last_index,
 855                                     write_bytes);
 856                 if (ret)
 857                         goto out;
 858
 859                 ret = btrfs_copy_from_user(pos, num_pages,
 860                                            write_bytes, pages, buf);
 861                 if (ret) {
 862                         btrfs_drop_pages(pages, num_pages);
 863                         goto out;
 864                 }
 865
 866                 ret = dirty_and_release_pages(NULL, root, file, pages,
 867                                               num_pages, pos, write_bytes);
 868                 btrfs_drop_pages(pages, num_pages);
 869                 if (ret)
 870                         goto out;
 871
 872                 buf += write_bytes;
 873                 count -= write_bytes;
 874                 pos += write_bytes;
 875                 num_written += write_bytes;
 876
 877                 balance_dirty_pages_ratelimited_nr(inode->i_mapping, num_pages);
 878                 if (num_pages < (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
 879                         btrfs_btree_balance_dirty(root, 1);
 880                 btrfs_throttle(root);
 881                 cond_resched();
 882         }
 883 out:
 884         mutex_unlock(&inode->i_mutex);
 885
 886 out_nolock:
 887         kfree(pages);
 888         if (pinned[0])
 889                 page_cache_release(pinned[0]);
 890         if (pinned[1])
 891                 page_cache_release(pinned[1]);
 892         *ppos = pos;
 893
 894         if (num_written > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
 895                 err = sync_page_range(inode, inode->i_mapping,
 896                                       start_pos, num_written);
 897                 if (err < 0)
 898                         num_written = err;
 899         }
 900         current->backing_dev_info = NULL;
 901         return num_written ? num_written : err;
 902 }
 903
 904 static int btrfs_sync_file(struct file *file,
 905                            struct dentry *dentry, int datasync)
 906 {
 907         struct inode *inode = dentry->d_inode;
 908         struct btrfs_root *root = BTRFS_I(inode)->root;
 909         int ret = 0;
 910         struct btrfs_trans_handle *trans;
 911
 912         /*
 913          * check the transaction that last modified this inode
 914          * and see if its already been committed
 915          */
 916         mutex_lock(&root->fs_info->fs_mutex);
 917         if (!BTRFS_I(inode)->last_trans)
 918                 goto out;
 919         mutex_lock(&root->fs_info->trans_mutex);
 920         if (BTRFS_I(inode)->last_trans <=
 921             root->fs_info->last_trans_committed) {
 922                 BTRFS_I(inode)->last_trans = 0;
 923                 mutex_unlock(&root->fs_info->trans_mutex);
 924                 goto out;
 925         }
 926         mutex_unlock(&root->fs_info->trans_mutex);
 927
 928         /*
 929          * ok we haven't committed the transaction yet, lets do a commit
 930          */
 931         trans = btrfs_start_transaction(root, 1);
 932         if (!trans) {
 933                 ret = -ENOMEM;
 934                 goto out;
 935         }
 936         ret = btrfs_commit_transaction(trans, root);
 937 out:
 938         mutex_unlock(&root->fs_info->fs_mutex);
 939         return ret > 0 ? EIO : ret;
 940 }
 941
 942 static struct vm_operations_struct btrfs_file_vm_ops = {
 943 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
 944         .nopage         = filemap_nopage,
 945         .populate       = filemap_populate,
 946 #else
 947         .fault          = filemap_fault,
 948 #endif
 949         .page_mkwrite   = btrfs_page_mkwrite,
 950 };
 951
 952 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
 953 {
 954         vma->vm_ops = &btrfs_file_vm_ops;
 955         file_accessed(filp);
 956         return 0;
 957 }
 958
 959 struct file_operations btrfs_file_operations = {
 960         .llseek         = generic_file_llseek,
 961         .read           = do_sync_read,
 962         .aio_read       = generic_file_aio_read,
 963         .splice_read    = generic_file_splice_read,
 964 #if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,18)
 965         .sendfile       = generic_file_sendfile,
 966 #endif
 967         .write          = btrfs_file_write,
 968         .mmap           = btrfs_file_mmap,
 969         .open           = generic_file_open,
 970         .fsync          = btrfs_sync_file,
 971         .unlocked_ioctl = btrfs_ioctl,
 972 #ifdef CONFIG_COMPAT
 973         .compat_ioctl   = btrfs_ioctl,
 974 #endif
 975 };
 976