fs/btrfs/file.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/fs.h>
  20 #include <linux/pagemap.h>
  21 #include <linux/highmem.h>
  22 #include <linux/time.h>
  23 #include <linux/init.h>
  24 #include <linux/string.h>
  25 #include <linux/backing-dev.h>
  26 #include <linux/mpage.h>
  27 #include <linux/swap.h>
  28 #include <linux/writeback.h>
  29 #include <linux/statfs.h>
  30 #include <linux/compat.h>
  31 #include "ctree.h"
  32 #include "disk-io.h"
  33 #include "transaction.h"
  34 #include "btrfs_inode.h"
  35 #include "ioctl.h"
  36 #include "print-tree.h"
  37 #include "tree-log.h"
  38 #include "locking.h"
  39 #include "compat.h"
  40
  41
  42 /* simple helper to fault in pages and copy.  This should go away
  43  * and be replaced with calls into generic code.
  44  */
  45 static noinline int btrfs_copy_from_user(loff_t pos, int num_pages,
  46                                          int write_bytes,
  47                                          struct page **prepared_pages,
  48                                          const char __user *buf)
  49 {
  50         long page_fault = 0;
  51         int i;
  52         int offset = pos & (PAGE_CACHE_SIZE - 1);
  53
  54         for (i = 0; i < num_pages && write_bytes > 0; i++, offset = 0) {
  55                 size_t count = min_t(size_t,
  56                                      PAGE_CACHE_SIZE - offset, write_bytes);
  57                 struct page *page = prepared_pages[i];
  58                 fault_in_pages_readable(buf, count);
  59
  60                 /* Copy data from userspace to the current page */
  61                 kmap(page);
  62                 page_fault = __copy_from_user(page_address(page) + offset,
  63                                               buf, count);
  64                 /* Flush processor's dcache for this page */
  65                 flush_dcache_page(page);
  66                 kunmap(page);
  67                 buf += count;
  68                 write_bytes -= count;
  69
  70                 if (page_fault)
  71                         break;
  72         }
  73         return page_fault ? -EFAULT : 0;
  74 }
  75
  76 /*
  77  * unlocks pages after btrfs_file_write is done with them
  78  */
  79 static noinline void btrfs_drop_pages(struct page **pages, size_t num_pages)
  80 {
  81         size_t i;
  82         for (i = 0; i < num_pages; i++) {
  83                 if (!pages[i])
  84                         break;
  85                 /* page checked is some magic around finding pages that
  86                  * have been modified without going through btrfs_set_page_dirty
  87                  * clear it here
  88                  */
  89                 ClearPageChecked(pages[i]);
  90                 unlock_page(pages[i]);
  91                 mark_page_accessed(pages[i]);
  92                 page_cache_release(pages[i]);
  93         }
  94 }
  95
  96 /*
  97  * after copy_from_user, pages need to be dirtied and we need to make
  98  * sure holes are created between the current EOF and the start of
  99  * any next extents (if required).
 100  *
 101  * this also makes the decision about creating an inline extent vs
 102  * doing real data extents, marking pages dirty and delalloc as required.
 103  */
 104 static noinline int dirty_and_release_pages(struct btrfs_trans_handle *trans,
 105                                    struct btrfs_root *root,
 106                                    struct file *file,
 107                                    struct page **pages,
 108                                    size_t num_pages,
 109                                    loff_t pos,
 110                                    size_t write_bytes)
 111 {
 112         int err = 0;
 113         int i;
 114         struct inode *inode = fdentry(file)->d_inode;
 115         u64 num_bytes;
 116         u64 start_pos;
 117         u64 end_of_last_block;
 118         u64 end_pos = pos + write_bytes;
 119         loff_t isize = i_size_read(inode);
 120
 121         start_pos = pos & ~((u64)root->sectorsize - 1);
 122         num_bytes = (write_bytes + pos - start_pos +
 123                     root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
 124
 125         end_of_last_block = start_pos + num_bytes - 1;
 126         err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block);
 127         if (err)
 128                 return err;
 129
 130         for (i = 0; i < num_pages; i++) {
 131                 struct page *p = pages[i];
 132                 SetPageUptodate(p);
 133                 ClearPageChecked(p);
 134                 set_page_dirty(p);
 135         }
 136         if (end_pos > isize) {
 137                 i_size_write(inode, end_pos);
 138                 /* we've only changed i_size in ram, and we haven't updated
 139                  * the disk i_size.  There is no need to log the inode
 140                  * at this time.
 141                  */
 142         }
 143         return err;
 144 }
 145
 146 /*
 147  * this drops all the extents in the cache that intersect the range
 148  * [start, end].  Existing extents are split as required.
 149  */
 150 int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
 151                             int skip_pinned)
 152 {
 153         struct extent_map *em;
 154         struct extent_map *split = NULL;
 155         struct extent_map *split2 = NULL;
 156         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
 157         u64 len = end - start + 1;
 158         int ret;
 159         int testend = 1;
 160         unsigned long flags;
 161         int compressed = 0;
 162
 163         WARN_ON(end < start);
 164         if (end == (u64)-1) {
 165                 len = (u64)-1;
 166                 testend = 0;
 167         }
 168         while (1) {
 169                 if (!split)
 170                         split = alloc_extent_map(GFP_NOFS);
 171                 if (!split2)
 172                         split2 = alloc_extent_map(GFP_NOFS);
 173
 174                 write_lock(&em_tree->lock);
 175                 em = lookup_extent_mapping(em_tree, start, len);
 176                 if (!em) {
 177                         write_unlock(&em_tree->lock);
 178                         break;
 179                 }
 180                 flags = em->flags;
 181                 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
 182                         if (testend && em->start + em->len >= start + len) {
 183                                 free_extent_map(em);
 184                                 write_unlock(&em_tree->lock);
 185                                 break;
 186                         }
 187                         start = em->start + em->len;
 188                         if (testend)
 189                                 len = start + len - (em->start + em->len);
 190                         free_extent_map(em);
 191                         write_unlock(&em_tree->lock);
 192                         continue;
 193                 }
 194                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 195                 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
 196                 remove_extent_mapping(em_tree, em);
 197
 198                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 199                     em->start < start) {
 200                         split->start = em->start;
 201                         split->len = start - em->start;
 202                         split->orig_start = em->orig_start;
 203                         split->block_start = em->block_start;
 204
 205                         if (compressed)
 206                                 split->block_len = em->block_len;
 207                         else
 208                                 split->block_len = split->len;
 209
 210                         split->bdev = em->bdev;
 211                         split->flags = flags;
 212                         ret = add_extent_mapping(em_tree, split);
 213                         BUG_ON(ret);
 214                         free_extent_map(split);
 215                         split = split2;
 216                         split2 = NULL;
 217                 }
 218                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 219                     testend && em->start + em->len > start + len) {
 220                         u64 diff = start + len - em->start;
 221
 222                         split->start = start + len;
 223                         split->len = em->start + em->len - (start + len);
 224                         split->bdev = em->bdev;
 225                         split->flags = flags;
 226
 227                         if (compressed) {
 228                                 split->block_len = em->block_len;
 229                                 split->block_start = em->block_start;
 230                                 split->orig_start = em->orig_start;
 231                         } else {
 232                                 split->block_len = split->len;
 233                                 split->block_start = em->block_start + diff;
 234                                 split->orig_start = split->start;
 235                         }
 236
 237                         ret = add_extent_mapping(em_tree, split);
 238                         BUG_ON(ret);
 239                         free_extent_map(split);
 240                         split = NULL;
 241                 }
 242                 write_unlock(&em_tree->lock);
 243
 244                 /* once for us */
 245                 free_extent_map(em);
 246                 /* once for the tree*/
 247                 free_extent_map(em);
 248         }
 249         if (split)
 250                 free_extent_map(split);
 251         if (split2)
 252                 free_extent_map(split2);
 253         return 0;
 254 }
 255
 256 /*
 257  * this is very complex, but the basic idea is to drop all extents
 258  * in the range start - end.  hint_block is filled in with a block number
 259  * that would be a good hint to the block allocator for this file.
 260  *
 261  * If an extent intersects the range but is not entirely inside the range
 262  * it is either truncated or split.  Anything entirely inside the range
 263  * is deleted from the tree.
 264  */
 265 int btrfs_drop_extents(struct btrfs_trans_handle *trans, struct inode *inode,
 266                        u64 start, u64 end, u64 *hint_byte, int drop_cache)
 267 {
 268         struct btrfs_root *root = BTRFS_I(inode)->root;
 269         struct extent_buffer *leaf;
 270         struct btrfs_file_extent_item *fi;
 271         struct btrfs_path *path;
 272         struct btrfs_key key;
 273         struct btrfs_key new_key;
 274         u64 search_start = start;
 275         u64 disk_bytenr = 0;
 276         u64 num_bytes = 0;
 277         u64 extent_offset = 0;
 278         u64 extent_end = 0;
 279         int del_nr = 0;
 280         int del_slot = 0;
 281         int extent_type;
 282         int recow;
 283         int ret;
 284
 285         if (drop_cache)
 286                 btrfs_drop_extent_cache(inode, start, end - 1, 0);
 287
 288         path = btrfs_alloc_path();
 289         if (!path)
 290                 return -ENOMEM;
 291
 292         while (1) {
 293                 recow = 0;
 294                 ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
 295                                                search_start, -1);
 296                 if (ret < 0)
 297                         break;
 298                 if (ret > 0 && path->slots[0] > 0 && search_start == start) {
 299                         leaf = path->nodes[0];
 300                         btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 301                         if (key.objectid == inode->i_ino &&
 302                             key.type == BTRFS_EXTENT_DATA_KEY)
 303                                 path->slots[0]--;
 304                 }
 305                 ret = 0;
 306 next_slot:
 307                 leaf = path->nodes[0];
 308                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 309                         BUG_ON(del_nr > 0);
 310                         ret = btrfs_next_leaf(root, path);
 311                         if (ret < 0)
 312                                 break;
 313                         if (ret > 0) {
 314                                 ret = 0;
 315                                 break;
 316                         }
 317                         leaf = path->nodes[0];
 318                         recow = 1;
 319                 }
 320
 321                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 322                 if (key.objectid > inode->i_ino ||
 323                     key.type > BTRFS_EXTENT_DATA_KEY || key.offset >= end)
 324                         break;
 325
 326                 fi = btrfs_item_ptr(leaf, path->slots[0],
 327                                     struct btrfs_file_extent_item);
 328                 extent_type = btrfs_file_extent_type(leaf, fi);
 329
 330                 if (extent_type == BTRFS_FILE_EXTENT_REG ||
 331                     extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
 332                         disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 333                         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
 334                         extent_offset = btrfs_file_extent_offset(leaf, fi);
 335                         extent_end = key.offset +
 336                                 btrfs_file_extent_num_bytes(leaf, fi);
 337                 } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 338                         extent_end = key.offset +
 339                                 btrfs_file_extent_inline_len(leaf, fi);
 340                 } else {
 341                         WARN_ON(1);
 342                         extent_end = search_start;
 343                 }
 344
 345                 if (extent_end <= search_start) {
 346                         path->slots[0]++;
 347                         goto next_slot;
 348                 }
 349
 350                 search_start = max(key.offset, start);
 351                 if (recow) {
 352                         btrfs_release_path(root, path);
 353                         continue;
 354                 }
 355
 356                 /*
 357                  *     | - range to drop - |
 358                  *  | -------- extent -------- |
 359                  */
 360                 if (start > key.offset && end < extent_end) {
 361                         BUG_ON(del_nr > 0);
 362                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 363
 364                         memcpy(&new_key, &key, sizeof(new_key));
 365                         new_key.offset = start;
 366                         ret = btrfs_duplicate_item(trans, root, path,
 367                                                    &new_key);
 368                         if (ret == -EAGAIN) {
 369                                 btrfs_release_path(root, path);
 370                                 continue;
 371                         }
 372                         if (ret < 0)
 373                                 break;
 374
 375                         leaf = path->nodes[0];
 376                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
 377                                             struct btrfs_file_extent_item);
 378                         btrfs_set_file_extent_num_bytes(leaf, fi,
 379                                                         start - key.offset);
 380
 381                         fi = btrfs_item_ptr(leaf, path->slots[0],
 382                                             struct btrfs_file_extent_item);
 383
 384                         extent_offset += start - key.offset;
 385                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
 386                         btrfs_set_file_extent_num_bytes(leaf, fi,
 387                                                         extent_end - start);
 388                         btrfs_mark_buffer_dirty(leaf);
 389
 390                         if (disk_bytenr > 0) {
 391                                 ret = btrfs_inc_extent_ref(trans, root,
 392                                                 disk_bytenr, num_bytes, 0,
 393                                                 root->root_key.objectid,
 394                                                 new_key.objectid,
 395                                                 start - extent_offset);
 396                                 BUG_ON(ret);
 397                                 *hint_byte = disk_bytenr;
 398                         }
 399                         key.offset = start;
 400                 }
 401                 /*
 402                  *  | ---- range to drop ----- |
 403                  *      | -------- extent -------- |
 404                  */
 405                 if (start <= key.offset && end < extent_end) {
 406                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 407
 408                         memcpy(&new_key, &key, sizeof(new_key));
 409                         new_key.offset = end;
 410                         btrfs_set_item_key_safe(trans, root, path, &new_key);
 411
 412                         extent_offset += end - key.offset;
 413                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
 414                         btrfs_set_file_extent_num_bytes(leaf, fi,
 415                                                         extent_end - end);
 416                         btrfs_mark_buffer_dirty(leaf);
 417                         if (disk_bytenr > 0) {
 418                                 inode_sub_bytes(inode, end - key.offset);
 419                                 *hint_byte = disk_bytenr;
 420                         }
 421                         break;
 422                 }
 423
 424                 search_start = extent_end;
 425                 /*
 426                  *       | ---- range to drop ----- |
 427                  *  | -------- extent -------- |
 428                  */
 429                 if (start > key.offset && end >= extent_end) {
 430                         BUG_ON(del_nr > 0);
 431                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 432
 433                         btrfs_set_file_extent_num_bytes(leaf, fi,
 434                                                         start - key.offset);
 435                         btrfs_mark_buffer_dirty(leaf);
 436                         if (disk_bytenr > 0) {
 437                                 inode_sub_bytes(inode, extent_end - start);
 438                                 *hint_byte = disk_bytenr;
 439                         }
 440                         if (end == extent_end)
 441                                 break;
 442
 443                         path->slots[0]++;
 444                         goto next_slot;
 445                 }
 446
 447                 /*
 448                  *  | ---- range to drop ----- |
 449                  *    | ------ extent ------ |
 450                  */
 451                 if (start <= key.offset && end >= extent_end) {
 452                         if (del_nr == 0) {
 453                                 del_slot = path->slots[0];
 454                                 del_nr = 1;
 455                         } else {
 456                                 BUG_ON(del_slot + del_nr != path->slots[0]);
 457                                 del_nr++;
 458                         }
 459
 460                         if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 461                                 inode_sub_bytes(inode,
 462                                                 extent_end - key.offset);
 463                                 extent_end = ALIGN(extent_end,
 464                                                    root->sectorsize);
 465                         } else if (disk_bytenr > 0) {
 466                                 ret = btrfs_free_extent(trans, root,
 467                                                 disk_bytenr, num_bytes, 0,
 468                                                 root->root_key.objectid,
 469                                                 key.objectid, key.offset -
 470                                                 extent_offset);
 471                                 BUG_ON(ret);
 472                                 inode_sub_bytes(inode,
 473                                                 extent_end - key.offset);
 474                                 *hint_byte = disk_bytenr;
 475                         }
 476
 477                         if (end == extent_end)
 478                                 break;
 479
 480                         if (path->slots[0] + 1 < btrfs_header_nritems(leaf)) {
 481                                 path->slots[0]++;
 482                                 goto next_slot;
 483                         }
 484
 485                         ret = btrfs_del_items(trans, root, path, del_slot,
 486                                               del_nr);
 487                         BUG_ON(ret);
 488
 489                         del_nr = 0;
 490                         del_slot = 0;
 491
 492                         btrfs_release_path(root, path);
 493                         continue;
 494                 }
 495
 496                 BUG_ON(1);
 497         }
 498
 499         if (del_nr > 0) {
 500                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
 501                 BUG_ON(ret);
 502         }
 503
 504         btrfs_free_path(path);
 505         return ret;
 506 }
 507
 508 static int extent_mergeable(struct extent_buffer *leaf, int slot,
 509                             u64 objectid, u64 bytenr, u64 *start, u64 *end)
 510 {
 511         struct btrfs_file_extent_item *fi;
 512         struct btrfs_key key;
 513         u64 extent_end;
 514
 515         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
 516                 return 0;
 517
 518         btrfs_item_key_to_cpu(leaf, &key, slot);
 519         if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
 520                 return 0;
 521
 522         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
 523         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
 524             btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
 525             btrfs_file_extent_compression(leaf, fi) ||
 526             btrfs_file_extent_encryption(leaf, fi) ||
 527             btrfs_file_extent_other_encoding(leaf, fi))
 528                 return 0;
 529
 530         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 531         if ((*start && *start != key.offset) || (*end && *end != extent_end))
 532                 return 0;
 533
 534         *start = key.offset;
 535         *end = extent_end;
 536         return 1;
 537 }
 538
 539 /*
 540  * Mark extent in the range start - end as written.
 541  *
 542  * This changes extent type from 'pre-allocated' to 'regular'. If only
 543  * part of extent is marked as written, the extent will be split into
 544  * two or three.
 545  */
 546 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
 547                               struct inode *inode, u64 start, u64 end)
 548 {
 549         struct btrfs_root *root = BTRFS_I(inode)->root;
 550         struct extent_buffer *leaf;
 551         struct btrfs_path *path;
 552         struct btrfs_file_extent_item *fi;
 553         struct btrfs_key key;
 554         struct btrfs_key new_key;
 555         u64 bytenr;
 556         u64 num_bytes;
 557         u64 extent_end;
 558         u64 orig_offset;
 559         u64 other_start;
 560         u64 other_end;
 561         u64 split;
 562         int del_nr = 0;
 563         int del_slot = 0;
 564         int ret;
 565
 566         btrfs_drop_extent_cache(inode, start, end - 1, 0);
 567
 568         path = btrfs_alloc_path();
 569         BUG_ON(!path);
 570 again:
 571         split = start;
 572         key.objectid = inode->i_ino;
 573         key.type = BTRFS_EXTENT_DATA_KEY;
 574         key.offset = split;
 575
 576         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 577         if (ret > 0 && path->slots[0] > 0)
 578                 path->slots[0]--;
 579
 580         leaf = path->nodes[0];
 581         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 582         BUG_ON(key.objectid != inode->i_ino ||
 583                key.type != BTRFS_EXTENT_DATA_KEY);
 584         fi = btrfs_item_ptr(leaf, path->slots[0],
 585                             struct btrfs_file_extent_item);
 586         BUG_ON(btrfs_file_extent_type(leaf, fi) !=
 587                BTRFS_FILE_EXTENT_PREALLOC);
 588         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 589         BUG_ON(key.offset > start || extent_end < end);
 590
 591         bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 592         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
 593         orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
 594
 595         while (start > key.offset || end < extent_end) {
 596                 if (key.offset == start)
 597                         split = end;
 598
 599                 memcpy(&new_key, &key, sizeof(new_key));
 600                 new_key.offset = split;
 601                 ret = btrfs_duplicate_item(trans, root, path, &new_key);
 602                 if (ret == -EAGAIN) {
 603                         btrfs_release_path(root, path);
 604                         goto again;
 605                 }
 606                 BUG_ON(ret < 0);
 607
 608                 leaf = path->nodes[0];
 609                 fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
 610                                     struct btrfs_file_extent_item);
 611                 btrfs_set_file_extent_num_bytes(leaf, fi,
 612                                                 split - key.offset);
 613
 614                 fi = btrfs_item_ptr(leaf, path->slots[0],
 615                                     struct btrfs_file_extent_item);
 616
 617                 btrfs_set_file_extent_offset(leaf, fi, split - orig_offset);
 618                 btrfs_set_file_extent_num_bytes(leaf, fi,
 619                                                 extent_end - split);
 620                 btrfs_mark_buffer_dirty(leaf);
 621
 622                 ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
 623                                            root->root_key.objectid,
 624                                            inode->i_ino, orig_offset);
 625                 BUG_ON(ret);
 626
 627                 if (split == start) {
 628                         key.offset = start;
 629                 } else {
 630                         BUG_ON(start != key.offset);
 631                         path->slots[0]--;
 632                         extent_end = end;
 633                 }
 634         }
 635
 636         fi = btrfs_item_ptr(leaf, path->slots[0],
 637                             struct btrfs_file_extent_item);
 638
 639         other_start = end;
 640         other_end = 0;
 641         if (extent_mergeable(leaf, path->slots[0] + 1, inode->i_ino,
 642                              bytenr, &other_start, &other_end)) {
 643                 extent_end = other_end;
 644                 del_slot = path->slots[0] + 1;
 645                 del_nr++;
 646                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
 647                                         0, root->root_key.objectid,
 648                                         inode->i_ino, orig_offset);
 649                 BUG_ON(ret);
 650         }
 651         other_start = 0;
 652         other_end = start;
 653         if (extent_mergeable(leaf, path->slots[0] - 1, inode->i_ino,
 654                              bytenr, &other_start, &other_end)) {
 655                 key.offset = other_start;
 656                 del_slot = path->slots[0];
 657                 del_nr++;
 658                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
 659                                         0, root->root_key.objectid,
 660                                         inode->i_ino, orig_offset);
 661                 BUG_ON(ret);
 662         }
 663         if (del_nr == 0) {
 664                 btrfs_set_file_extent_type(leaf, fi,
 665                                            BTRFS_FILE_EXTENT_REG);
 666                 btrfs_mark_buffer_dirty(leaf);
 667                 goto out;
 668         }
 669
 670         fi = btrfs_item_ptr(leaf, del_slot - 1,
 671                             struct btrfs_file_extent_item);
 672         btrfs_set_file_extent_type(leaf, fi, BTRFS_FILE_EXTENT_REG);
 673         btrfs_set_file_extent_num_bytes(leaf, fi,
 674                                         extent_end - key.offset);
 675         btrfs_mark_buffer_dirty(leaf);
 676
 677         ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
 678         BUG_ON(ret);
 679 out:
 680         btrfs_free_path(path);
 681         return 0;
 682 }
 683
 684 /*
 685  * this gets pages into the page cache and locks them down, it also properly
 686  * waits for data=ordered extents to finish before allowing the pages to be
 687  * modified.
 688  */
 689 static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
 690                          struct page **pages, size_t num_pages,
 691                          loff_t pos, unsigned long first_index,
 692                          unsigned long last_index, size_t write_bytes)
 693 {
 694         int i;
 695         unsigned long index = pos >> PAGE_CACHE_SHIFT;
 696         struct inode *inode = fdentry(file)->d_inode;
 697         int err = 0;
 698         u64 start_pos;
 699         u64 last_pos;
 700
 701         start_pos = pos & ~((u64)root->sectorsize - 1);
 702         last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
 703
 704         if (start_pos > inode->i_size) {
 705                 err = btrfs_cont_expand(inode, start_pos);
 706                 if (err)
 707                         return err;
 708         }
 709
 710         memset(pages, 0, num_pages * sizeof(struct page *));
 711 again:
 712         for (i = 0; i < num_pages; i++) {
 713                 pages[i] = grab_cache_page(inode->i_mapping, index + i);
 714                 if (!pages[i]) {
 715                         err = -ENOMEM;
 716                         BUG_ON(1);
 717                 }
 718                 wait_on_page_writeback(pages[i]);
 719         }
 720         if (start_pos < inode->i_size) {
 721                 struct btrfs_ordered_extent *ordered;
 722                 lock_extent(&BTRFS_I(inode)->io_tree,
 723                             start_pos, last_pos - 1, GFP_NOFS);
 724                 ordered = btrfs_lookup_first_ordered_extent(inode,
 725                                                             last_pos - 1);
 726                 if (ordered &&
 727                     ordered->file_offset + ordered->len > start_pos &&
 728                     ordered->file_offset < last_pos) {
 729                         btrfs_put_ordered_extent(ordered);
 730                         unlock_extent(&BTRFS_I(inode)->io_tree,
 731                                       start_pos, last_pos - 1, GFP_NOFS);
 732                         for (i = 0; i < num_pages; i++) {
 733                                 unlock_page(pages[i]);
 734                                 page_cache_release(pages[i]);
 735                         }
 736                         btrfs_wait_ordered_range(inode, start_pos,
 737                                                  last_pos - start_pos);
 738                         goto again;
 739                 }
 740                 if (ordered)
 741                         btrfs_put_ordered_extent(ordered);
 742
 743                 clear_extent_bits(&BTRFS_I(inode)->io_tree, start_pos,
 744                                   last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC |
 745                                   EXTENT_DO_ACCOUNTING,
 746                                   GFP_NOFS);
 747                 unlock_extent(&BTRFS_I(inode)->io_tree,
 748                               start_pos, last_pos - 1, GFP_NOFS);
 749         }
 750         for (i = 0; i < num_pages; i++) {
 751                 clear_page_dirty_for_io(pages[i]);
 752                 set_page_extent_mapped(pages[i]);
 753                 WARN_ON(!PageLocked(pages[i]));
 754         }
 755         return 0;
 756 }
 757
 758 static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
 759                                 size_t count, loff_t *ppos)
 760 {
 761         loff_t pos;
 762         loff_t start_pos;
 763         ssize_t num_written = 0;
 764         ssize_t err = 0;
 765         int ret = 0;
 766         struct inode *inode = fdentry(file)->d_inode;
 767         struct btrfs_root *root = BTRFS_I(inode)->root;
 768         struct page **pages = NULL;
 769         int nrptrs;
 770         struct page *pinned[2];
 771         unsigned long first_index;
 772         unsigned long last_index;
 773         int will_write;
 774
 775         will_write = ((file->f_flags & O_DSYNC) || IS_SYNC(inode) ||
 776                       (file->f_flags & O_DIRECT));
 777
 778         nrptrs = min((count + PAGE_CACHE_SIZE - 1) / PAGE_CACHE_SIZE,
 779                      PAGE_CACHE_SIZE / (sizeof(struct page *)));
 780         pinned[0] = NULL;
 781         pinned[1] = NULL;
 782
 783         pos = *ppos;
 784         start_pos = pos;
 785
 786         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
 787
 788         /* do the reserve before the mutex lock in case we have to do some
 789          * flushing.  We wouldn't deadlock, but this is more polite.
 790          */
 791         err = btrfs_reserve_metadata_for_delalloc(root, inode, 1);
 792         if (err)
 793                 goto out_nolock;
 794
 795         mutex_lock(&inode->i_mutex);
 796
 797         current->backing_dev_info = inode->i_mapping->backing_dev_info;
 798         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
 799         if (err)
 800                 goto out;
 801
 802         if (count == 0)
 803                 goto out;
 804
 805         err = file_remove_suid(file);
 806         if (err)
 807                 goto out;
 808
 809         file_update_time(file);
 810
 811         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
 812
 813         /* generic_write_checks can change our pos */
 814         start_pos = pos;
 815
 816         BTRFS_I(inode)->sequence++;
 817         first_index = pos >> PAGE_CACHE_SHIFT;
 818         last_index = (pos + count) >> PAGE_CACHE_SHIFT;
 819
 820         /*
 821          * there are lots of better ways to do this, but this code
 822          * makes sure the first and last page in the file range are
 823          * up to date and ready for cow
 824          */
 825         if ((pos & (PAGE_CACHE_SIZE - 1))) {
 826                 pinned[0] = grab_cache_page(inode->i_mapping, first_index);
 827                 if (!PageUptodate(pinned[0])) {
 828                         ret = btrfs_readpage(NULL, pinned[0]);
 829                         BUG_ON(ret);
 830                         wait_on_page_locked(pinned[0]);
 831                 } else {
 832                         unlock_page(pinned[0]);
 833                 }
 834         }
 835         if ((pos + count) & (PAGE_CACHE_SIZE - 1)) {
 836                 pinned[1] = grab_cache_page(inode->i_mapping, last_index);
 837                 if (!PageUptodate(pinned[1])) {
 838                         ret = btrfs_readpage(NULL, pinned[1]);
 839                         BUG_ON(ret);
 840                         wait_on_page_locked(pinned[1]);
 841                 } else {
 842                         unlock_page(pinned[1]);
 843                 }
 844         }
 845
 846         while (count > 0) {
 847                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
 848                 size_t write_bytes = min(count, nrptrs *
 849                                         (size_t)PAGE_CACHE_SIZE -
 850                                          offset);
 851                 size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
 852                                         PAGE_CACHE_SHIFT;
 853
 854                 WARN_ON(num_pages > nrptrs);
 855                 memset(pages, 0, sizeof(struct page *) * nrptrs);
 856
 857                 ret = btrfs_check_data_free_space(root, inode, write_bytes);
 858                 if (ret)
 859                         goto out;
 860
 861                 ret = prepare_pages(root, file, pages, num_pages,
 862                                     pos, first_index, last_index,
 863                                     write_bytes);
 864                 if (ret) {
 865                         btrfs_free_reserved_data_space(root, inode,
 866                                                        write_bytes);
 867                         goto out;
 868                 }
 869
 870                 ret = btrfs_copy_from_user(pos, num_pages,
 871                                            write_bytes, pages, buf);
 872                 if (ret) {
 873                         btrfs_free_reserved_data_space(root, inode,
 874                                                        write_bytes);
 875                         btrfs_drop_pages(pages, num_pages);
 876                         goto out;
 877                 }
 878
 879                 ret = dirty_and_release_pages(NULL, root, file, pages,
 880                                               num_pages, pos, write_bytes);
 881                 btrfs_drop_pages(pages, num_pages);
 882                 if (ret) {
 883                         btrfs_free_reserved_data_space(root, inode,
 884                                                        write_bytes);
 885                         goto out;
 886                 }
 887
 888                 if (will_write) {
 889                         filemap_fdatawrite_range(inode->i_mapping, pos,
 890                                                  pos + write_bytes - 1);
 891                 } else {
 892                         balance_dirty_pages_ratelimited_nr(inode->i_mapping,
 893                                                            num_pages);
 894                         if (num_pages <
 895                             (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
 896                                 btrfs_btree_balance_dirty(root, 1);
 897                         btrfs_throttle(root);
 898                 }
 899
 900                 buf += write_bytes;
 901                 count -= write_bytes;
 902                 pos += write_bytes;
 903                 num_written += write_bytes;
 904
 905                 cond_resched();
 906         }
 907 out:
 908         mutex_unlock(&inode->i_mutex);
 909         if (ret)
 910                 err = ret;
 911         btrfs_unreserve_metadata_for_delalloc(root, inode, 1);
 912
 913 out_nolock:
 914         kfree(pages);
 915         if (pinned[0])
 916                 page_cache_release(pinned[0]);
 917         if (pinned[1])
 918                 page_cache_release(pinned[1]);
 919         *ppos = pos;
 920
 921         /*
 922          * we want to make sure fsync finds this change
 923          * but we haven't joined a transaction running right now.
 924          *
 925          * Later on, someone is sure to update the inode and get the
 926          * real transid recorded.
 927          *
 928          * We set last_trans now to the fs_info generation + 1,
 929          * this will either be one more than the running transaction
 930          * or the generation used for the next transaction if there isn't
 931          * one running right now.
 932          */
 933         BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
 934
 935         if (num_written > 0 && will_write) {
 936                 struct btrfs_trans_handle *trans;
 937
 938                 err = btrfs_wait_ordered_range(inode, start_pos, num_written);
 939                 if (err)
 940                         num_written = err;
 941
 942                 if ((file->f_flags & O_DSYNC) || IS_SYNC(inode)) {
 943                         trans = btrfs_start_transaction(root, 1);
 944                         ret = btrfs_log_dentry_safe(trans, root,
 945                                                     file->f_dentry);
 946                         if (ret == 0) {
 947                                 ret = btrfs_sync_log(trans, root);
 948                                 if (ret == 0)
 949                                         btrfs_end_transaction(trans, root);
 950                                 else
 951                                         btrfs_commit_transaction(trans, root);
 952                         } else if (ret != BTRFS_NO_LOG_SYNC) {
 953                                 btrfs_commit_transaction(trans, root);
 954                         } else {
 955                                 btrfs_end_transaction(trans, root);
 956                         }
 957                 }
 958                 if (file->f_flags & O_DIRECT) {
 959                         invalidate_mapping_pages(inode->i_mapping,
 960                               start_pos >> PAGE_CACHE_SHIFT,
 961                              (start_pos + num_written - 1) >> PAGE_CACHE_SHIFT);
 962                 }
 963         }
 964         current->backing_dev_info = NULL;
 965         return num_written ? num_written : err;
 966 }
 967
 968 int btrfs_release_file(struct inode *inode, struct file *filp)
 969 {
 970         /*
 971          * ordered_data_close is set by settattr when we are about to truncate
 972          * a file from a non-zero size to a zero size.  This tries to
 973          * flush down new bytes that may have been written if the
 974          * application were using truncate to replace a file in place.
 975          */
 976         if (BTRFS_I(inode)->ordered_data_close) {
 977                 BTRFS_I(inode)->ordered_data_close = 0;
 978                 btrfs_add_ordered_operation(NULL, BTRFS_I(inode)->root, inode);
 979                 if (inode->i_size > BTRFS_ORDERED_OPERATIONS_FLUSH_LIMIT)
 980                         filemap_flush(inode->i_mapping);
 981         }
 982         if (filp->private_data)
 983                 btrfs_ioctl_trans_end(filp);
 984         return 0;
 985 }
 986
 987 /*
 988  * fsync call for both files and directories.  This logs the inode into
 989  * the tree log instead of forcing full commits whenever possible.
 990  *
 991  * It needs to call filemap_fdatawait so that all ordered extent updates are
 992  * in the metadata btree are up to date for copying to the log.
 993  *
 994  * It drops the inode mutex before doing the tree log commit.  This is an
 995  * important optimization for directories because holding the mutex prevents
 996  * new operations on the dir while we write to disk.
 997  */
 998 int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
 999 {
1000         struct inode *inode = dentry->d_inode;
1001         struct btrfs_root *root = BTRFS_I(inode)->root;
1002         int ret = 0;
1003         struct btrfs_trans_handle *trans;
1004
1005
1006         /* we wait first, since the writeback may change the inode */
1007         root->log_batch++;
1008         /* the VFS called filemap_fdatawrite for us */
1009         btrfs_wait_ordered_range(inode, 0, (u64)-1);
1010         root->log_batch++;
1011
1012         /*
1013          * check the transaction that last modified this inode
1014          * and see if its already been committed
1015          */
1016         if (!BTRFS_I(inode)->last_trans)
1017                 goto out;
1018
1019         /*
1020          * if the last transaction that changed this file was before
1021          * the current transaction, we can bail out now without any
1022          * syncing
1023          */
1024         mutex_lock(&root->fs_info->trans_mutex);
1025         if (BTRFS_I(inode)->last_trans <=
1026             root->fs_info->last_trans_committed) {
1027                 BTRFS_I(inode)->last_trans = 0;
1028                 mutex_unlock(&root->fs_info->trans_mutex);
1029                 goto out;
1030         }
1031         mutex_unlock(&root->fs_info->trans_mutex);
1032
1033         /*
1034          * ok we haven't committed the transaction yet, lets do a commit
1035          */
1036         if (file && file->private_data)
1037                 btrfs_ioctl_trans_end(file);
1038
1039         trans = btrfs_start_transaction(root, 1);
1040         if (!trans) {
1041                 ret = -ENOMEM;
1042                 goto out;
1043         }
1044
1045         ret = btrfs_log_dentry_safe(trans, root, dentry);
1046         if (ret < 0)
1047                 goto out;
1048
1049         /* we've logged all the items and now have a consistent
1050          * version of the file in the log.  It is possible that
1051          * someone will come in and modify the file, but that's
1052          * fine because the log is consistent on disk, and we
1053          * have references to all of the file's extents
1054          *
1055          * It is possible that someone will come in and log the
1056          * file again, but that will end up using the synchronization
1057          * inside btrfs_sync_log to keep things safe.
1058          */
1059         mutex_unlock(&dentry->d_inode->i_mutex);
1060
1061         if (ret != BTRFS_NO_LOG_SYNC) {
1062                 if (ret > 0) {
1063                         ret = btrfs_commit_transaction(trans, root);
1064                 } else {
1065                         ret = btrfs_sync_log(trans, root);
1066                         if (ret == 0)
1067                                 ret = btrfs_end_transaction(trans, root);
1068                         else
1069                                 ret = btrfs_commit_transaction(trans, root);
1070                 }
1071         } else {
1072                 ret = btrfs_end_transaction(trans, root);
1073         }
1074         mutex_lock(&dentry->d_inode->i_mutex);
1075 out:
1076         return ret > 0 ? EIO : ret;
1077 }
1078
1079 static const struct vm_operations_struct btrfs_file_vm_ops = {
1080         .fault          = filemap_fault,
1081         .page_mkwrite   = btrfs_page_mkwrite,
1082 };
1083
1084 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
1085 {
1086         vma->vm_ops = &btrfs_file_vm_ops;
1087         file_accessed(filp);
1088         return 0;
1089 }
1090
1091 const struct file_operations btrfs_file_operations = {
1092         .llseek         = generic_file_llseek,
1093         .read           = do_sync_read,
1094         .aio_read       = generic_file_aio_read,
1095         .splice_read    = generic_file_splice_read,
1096         .write          = btrfs_file_write,
1097         .mmap           = btrfs_file_mmap,
1098         .open           = generic_file_open,
1099         .release        = btrfs_release_file,
1100         .fsync          = btrfs_sync_file,
1101         .unlocked_ioctl = btrfs_ioctl,
1102 #ifdef CONFIG_COMPAT
1103         .compat_ioctl   = btrfs_ioctl,
1104 #endif
1105 };