SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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                                         NULL);
 128         if (err)
 129                 return err;
 130
 131         for (i = 0; i < num_pages; i++) {
 132                 struct page *p = pages[i];
 133                 SetPageUptodate(p);
 134                 ClearPageChecked(p);
 135                 set_page_dirty(p);
 136         }
 137         if (end_pos > isize) {
 138                 i_size_write(inode, end_pos);
 139                 /* we've only changed i_size in ram, and we haven't updated
 140                  * the disk i_size.  There is no need to log the inode
 141                  * at this time.
 142                  */
 143         }
 144         return err;
 145 }
 146
 147 /*
 148  * this drops all the extents in the cache that intersect the range
 149  * [start, end].  Existing extents are split as required.
 150  */
 151 int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
 152                             int skip_pinned)
 153 {
 154         struct extent_map *em;
 155         struct extent_map *split = NULL;
 156         struct extent_map *split2 = NULL;
 157         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
 158         u64 len = end - start + 1;
 159         int ret;
 160         int testend = 1;
 161         unsigned long flags;
 162         int compressed = 0;
 163
 164         WARN_ON(end < start);
 165         if (end == (u64)-1) {
 166                 len = (u64)-1;
 167                 testend = 0;
 168         }
 169         while (1) {
 170                 if (!split)
 171                         split = alloc_extent_map(GFP_NOFS);
 172                 if (!split2)
 173                         split2 = alloc_extent_map(GFP_NOFS);
 174
 175                 write_lock(&em_tree->lock);
 176                 em = lookup_extent_mapping(em_tree, start, len);
 177                 if (!em) {
 178                         write_unlock(&em_tree->lock);
 179                         break;
 180                 }
 181                 flags = em->flags;
 182                 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
 183                         if (testend && em->start + em->len >= start + len) {
 184                                 free_extent_map(em);
 185                                 write_unlock(&em_tree->lock);
 186                                 break;
 187                         }
 188                         start = em->start + em->len;
 189                         if (testend)
 190                                 len = start + len - (em->start + em->len);
 191                         free_extent_map(em);
 192                         write_unlock(&em_tree->lock);
 193                         continue;
 194                 }
 195                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 196                 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
 197                 remove_extent_mapping(em_tree, em);
 198
 199                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 200                     em->start < start) {
 201                         split->start = em->start;
 202                         split->len = start - em->start;
 203                         split->orig_start = em->orig_start;
 204                         split->block_start = em->block_start;
 205
 206                         if (compressed)
 207                                 split->block_len = em->block_len;
 208                         else
 209                                 split->block_len = split->len;
 210
 211                         split->bdev = em->bdev;
 212                         split->flags = flags;
 213                         ret = add_extent_mapping(em_tree, split);
 214                         BUG_ON(ret);
 215                         free_extent_map(split);
 216                         split = split2;
 217                         split2 = NULL;
 218                 }
 219                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 220                     testend && em->start + em->len > start + len) {
 221                         u64 diff = start + len - em->start;
 222
 223                         split->start = start + len;
 224                         split->len = em->start + em->len - (start + len);
 225                         split->bdev = em->bdev;
 226                         split->flags = flags;
 227
 228                         if (compressed) {
 229                                 split->block_len = em->block_len;
 230                                 split->block_start = em->block_start;
 231                                 split->orig_start = em->orig_start;
 232                         } else {
 233                                 split->block_len = split->len;
 234                                 split->block_start = em->block_start + diff;
 235                                 split->orig_start = split->start;
 236                         }
 237
 238                         ret = add_extent_mapping(em_tree, split);
 239                         BUG_ON(ret);
 240                         free_extent_map(split);
 241                         split = NULL;
 242                 }
 243                 write_unlock(&em_tree->lock);
 244
 245                 /* once for us */
 246                 free_extent_map(em);
 247                 /* once for the tree*/
 248                 free_extent_map(em);
 249         }
 250         if (split)
 251                 free_extent_map(split);
 252         if (split2)
 253                 free_extent_map(split2);
 254         return 0;
 255 }
 256
 257 /*
 258  * this is very complex, but the basic idea is to drop all extents
 259  * in the range start - end.  hint_block is filled in with a block number
 260  * that would be a good hint to the block allocator for this file.
 261  *
 262  * If an extent intersects the range but is not entirely inside the range
 263  * it is either truncated or split.  Anything entirely inside the range
 264  * is deleted from the tree.
 265  */
 266 int btrfs_drop_extents(struct btrfs_trans_handle *trans, struct inode *inode,
 267                        u64 start, u64 end, u64 *hint_byte, int drop_cache)
 268 {
 269         struct btrfs_root *root = BTRFS_I(inode)->root;
 270         struct extent_buffer *leaf;
 271         struct btrfs_file_extent_item *fi;
 272         struct btrfs_path *path;
 273         struct btrfs_key key;
 274         struct btrfs_key new_key;
 275         u64 search_start = start;
 276         u64 disk_bytenr = 0;
 277         u64 num_bytes = 0;
 278         u64 extent_offset = 0;
 279         u64 extent_end = 0;
 280         int del_nr = 0;
 281         int del_slot = 0;
 282         int extent_type;
 283         int recow;
 284         int ret;
 285
 286         if (drop_cache)
 287                 btrfs_drop_extent_cache(inode, start, end - 1, 0);
 288
 289         path = btrfs_alloc_path();
 290         if (!path)
 291                 return -ENOMEM;
 292
 293         while (1) {
 294                 recow = 0;
 295                 ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
 296                                                search_start, -1);
 297                 if (ret < 0)
 298                         break;
 299                 if (ret > 0 && path->slots[0] > 0 && search_start == start) {
 300                         leaf = path->nodes[0];
 301                         btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 302                         if (key.objectid == inode->i_ino &&
 303                             key.type == BTRFS_EXTENT_DATA_KEY)
 304                                 path->slots[0]--;
 305                 }
 306                 ret = 0;
 307 next_slot:
 308                 leaf = path->nodes[0];
 309                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 310                         BUG_ON(del_nr > 0);
 311                         ret = btrfs_next_leaf(root, path);
 312                         if (ret < 0)
 313                                 break;
 314                         if (ret > 0) {
 315                                 ret = 0;
 316                                 break;
 317                         }
 318                         leaf = path->nodes[0];
 319                         recow = 1;
 320                 }
 321
 322                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 323                 if (key.objectid > inode->i_ino ||
 324                     key.type > BTRFS_EXTENT_DATA_KEY || key.offset >= end)
 325                         break;
 326
 327                 fi = btrfs_item_ptr(leaf, path->slots[0],
 328                                     struct btrfs_file_extent_item);
 329                 extent_type = btrfs_file_extent_type(leaf, fi);
 330
 331                 if (extent_type == BTRFS_FILE_EXTENT_REG ||
 332                     extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
 333                         disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 334                         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
 335                         extent_offset = btrfs_file_extent_offset(leaf, fi);
 336                         extent_end = key.offset +
 337                                 btrfs_file_extent_num_bytes(leaf, fi);
 338                 } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 339                         extent_end = key.offset +
 340                                 btrfs_file_extent_inline_len(leaf, fi);
 341                 } else {
 342                         WARN_ON(1);
 343                         extent_end = search_start;
 344                 }
 345
 346                 if (extent_end <= search_start) {
 347                         path->slots[0]++;
 348                         goto next_slot;
 349                 }
 350
 351                 search_start = max(key.offset, start);
 352                 if (recow) {
 353                         btrfs_release_path(root, path);
 354                         continue;
 355                 }
 356
 357                 /*
 358                  *     | - range to drop - |
 359                  *  | -------- extent -------- |
 360                  */
 361                 if (start > key.offset && end < extent_end) {
 362                         BUG_ON(del_nr > 0);
 363                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 364
 365                         memcpy(&new_key, &key, sizeof(new_key));
 366                         new_key.offset = start;
 367                         ret = btrfs_duplicate_item(trans, root, path,
 368                                                    &new_key);
 369                         if (ret == -EAGAIN) {
 370                                 btrfs_release_path(root, path);
 371                                 continue;
 372                         }
 373                         if (ret < 0)
 374                                 break;
 375
 376                         leaf = path->nodes[0];
 377                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
 378                                             struct btrfs_file_extent_item);
 379                         btrfs_set_file_extent_num_bytes(leaf, fi,
 380                                                         start - key.offset);
 381
 382                         fi = btrfs_item_ptr(leaf, path->slots[0],
 383                                             struct btrfs_file_extent_item);
 384
 385                         extent_offset += start - key.offset;
 386                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
 387                         btrfs_set_file_extent_num_bytes(leaf, fi,
 388                                                         extent_end - start);
 389                         btrfs_mark_buffer_dirty(leaf);
 390
 391                         if (disk_bytenr > 0) {
 392                                 ret = btrfs_inc_extent_ref(trans, root,
 393                                                 disk_bytenr, num_bytes, 0,
 394                                                 root->root_key.objectid,
 395                                                 new_key.objectid,
 396                                                 start - extent_offset);
 397                                 BUG_ON(ret);
 398                                 *hint_byte = disk_bytenr;
 399                         }
 400                         key.offset = start;
 401                 }
 402                 /*
 403                  *  | ---- range to drop ----- |
 404                  *      | -------- extent -------- |
 405                  */
 406                 if (start <= key.offset && end < extent_end) {
 407                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 408
 409                         memcpy(&new_key, &key, sizeof(new_key));
 410                         new_key.offset = end;
 411                         btrfs_set_item_key_safe(trans, root, path, &new_key);
 412
 413                         extent_offset += end - key.offset;
 414                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
 415                         btrfs_set_file_extent_num_bytes(leaf, fi,
 416                                                         extent_end - end);
 417                         btrfs_mark_buffer_dirty(leaf);
 418                         if (disk_bytenr > 0) {
 419                                 inode_sub_bytes(inode, end - key.offset);
 420                                 *hint_byte = disk_bytenr;
 421                         }
 422                         break;
 423                 }
 424
 425                 search_start = extent_end;
 426                 /*
 427                  *       | ---- range to drop ----- |
 428                  *  | -------- extent -------- |
 429                  */
 430                 if (start > key.offset && end >= extent_end) {
 431                         BUG_ON(del_nr > 0);
 432                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 433
 434                         btrfs_set_file_extent_num_bytes(leaf, fi,
 435                                                         start - key.offset);
 436                         btrfs_mark_buffer_dirty(leaf);
 437                         if (disk_bytenr > 0) {
 438                                 inode_sub_bytes(inode, extent_end - start);
 439                                 *hint_byte = disk_bytenr;
 440                         }
 441                         if (end == extent_end)
 442                                 break;
 443
 444                         path->slots[0]++;
 445                         goto next_slot;
 446                 }
 447
 448                 /*
 449                  *  | ---- range to drop ----- |
 450                  *    | ------ extent ------ |
 451                  */
 452                 if (start <= key.offset && end >= extent_end) {
 453                         if (del_nr == 0) {
 454                                 del_slot = path->slots[0];
 455                                 del_nr = 1;
 456                         } else {
 457                                 BUG_ON(del_slot + del_nr != path->slots[0]);
 458                                 del_nr++;
 459                         }
 460
 461                         if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 462                                 inode_sub_bytes(inode,
 463                                                 extent_end - key.offset);
 464                                 extent_end = ALIGN(extent_end,
 465                                                    root->sectorsize);
 466                         } else if (disk_bytenr > 0) {
 467                                 ret = btrfs_free_extent(trans, root,
 468                                                 disk_bytenr, num_bytes, 0,
 469                                                 root->root_key.objectid,
 470                                                 key.objectid, key.offset -
 471                                                 extent_offset);
 472                                 BUG_ON(ret);
 473                                 inode_sub_bytes(inode,
 474                                                 extent_end - key.offset);
 475                                 *hint_byte = disk_bytenr;
 476                         }
 477
 478                         if (end == extent_end)
 479                                 break;
 480
 481                         if (path->slots[0] + 1 < btrfs_header_nritems(leaf)) {
 482                                 path->slots[0]++;
 483                                 goto next_slot;
 484                         }
 485
 486                         ret = btrfs_del_items(trans, root, path, del_slot,
 487                                               del_nr);
 488                         BUG_ON(ret);
 489
 490                         del_nr = 0;
 491                         del_slot = 0;
 492
 493                         btrfs_release_path(root, path);
 494                         continue;
 495                 }
 496
 497                 BUG_ON(1);
 498         }
 499
 500         if (del_nr > 0) {
 501                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
 502                 BUG_ON(ret);
 503         }
 504
 505         btrfs_free_path(path);
 506         return ret;
 507 }
 508
 509 static int extent_mergeable(struct extent_buffer *leaf, int slot,
 510                             u64 objectid, u64 bytenr, u64 orig_offset,
 511                             u64 *start, u64 *end)
 512 {
 513         struct btrfs_file_extent_item *fi;
 514         struct btrfs_key key;
 515         u64 extent_end;
 516
 517         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
 518                 return 0;
 519
 520         btrfs_item_key_to_cpu(leaf, &key, slot);
 521         if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
 522                 return 0;
 523
 524         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
 525         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
 526             btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
 527             btrfs_file_extent_offset(leaf, fi) != key.offset - orig_offset ||
 528             btrfs_file_extent_compression(leaf, fi) ||
 529             btrfs_file_extent_encryption(leaf, fi) ||
 530             btrfs_file_extent_other_encoding(leaf, fi))
 531                 return 0;
 532
 533         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 534         if ((*start && *start != key.offset) || (*end && *end != extent_end))
 535                 return 0;
 536
 537         *start = key.offset;
 538         *end = extent_end;
 539         return 1;
 540 }
 541
 542 /*
 543  * Mark extent in the range start - end as written.
 544  *
 545  * This changes extent type from 'pre-allocated' to 'regular'. If only
 546  * part of extent is marked as written, the extent will be split into
 547  * two or three.
 548  */
 549 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
 550                               struct inode *inode, u64 start, u64 end)
 551 {
 552         struct btrfs_root *root = BTRFS_I(inode)->root;
 553         struct extent_buffer *leaf;
 554         struct btrfs_path *path;
 555         struct btrfs_file_extent_item *fi;
 556         struct btrfs_key key;
 557         struct btrfs_key new_key;
 558         u64 bytenr;
 559         u64 num_bytes;
 560         u64 extent_end;
 561         u64 orig_offset;
 562         u64 other_start;
 563         u64 other_end;
 564         u64 split;
 565         int del_nr = 0;
 566         int del_slot = 0;
 567         int recow;
 568         int ret;
 569
 570         btrfs_drop_extent_cache(inode, start, end - 1, 0);
 571
 572         path = btrfs_alloc_path();
 573         BUG_ON(!path);
 574 again:
 575         recow = 0;
 576         split = start;
 577         key.objectid = inode->i_ino;
 578         key.type = BTRFS_EXTENT_DATA_KEY;
 579         key.offset = split;
 580
 581         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 582         if (ret > 0 && path->slots[0] > 0)
 583                 path->slots[0]--;
 584
 585         leaf = path->nodes[0];
 586         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 587         BUG_ON(key.objectid != inode->i_ino ||
 588                key.type != BTRFS_EXTENT_DATA_KEY);
 589         fi = btrfs_item_ptr(leaf, path->slots[0],
 590                             struct btrfs_file_extent_item);
 591         BUG_ON(btrfs_file_extent_type(leaf, fi) !=
 592                BTRFS_FILE_EXTENT_PREALLOC);
 593         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 594         BUG_ON(key.offset > start || extent_end < end);
 595
 596         bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 597         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
 598         orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
 599         memcpy(&new_key, &key, sizeof(new_key));
 600
 601         if (start == key.offset && end < extent_end) {
 602                 other_start = 0;
 603                 other_end = start;
 604                 if (extent_mergeable(leaf, path->slots[0] - 1,
 605                                      inode->i_ino, bytenr, orig_offset,
 606                                      &other_start, &other_end)) {
 607                         new_key.offset = end;
 608                         btrfs_set_item_key_safe(trans, root, path, &new_key);
 609                         fi = btrfs_item_ptr(leaf, path->slots[0],
 610                                             struct btrfs_file_extent_item);
 611                         btrfs_set_file_extent_num_bytes(leaf, fi,
 612                                                         extent_end - end);
 613                         btrfs_set_file_extent_offset(leaf, fi,
 614                                                      end - orig_offset);
 615                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
 616                                             struct btrfs_file_extent_item);
 617                         btrfs_set_file_extent_num_bytes(leaf, fi,
 618                                                         end - other_start);
 619                         btrfs_mark_buffer_dirty(leaf);
 620                         goto out;
 621                 }
 622         }
 623
 624         if (start > key.offset && end == extent_end) {
 625                 other_start = end;
 626                 other_end = 0;
 627                 if (extent_mergeable(leaf, path->slots[0] + 1,
 628                                      inode->i_ino, bytenr, orig_offset,
 629                                      &other_start, &other_end)) {
 630                         fi = btrfs_item_ptr(leaf, path->slots[0],
 631                                             struct btrfs_file_extent_item);
 632                         btrfs_set_file_extent_num_bytes(leaf, fi,
 633                                                         start - key.offset);
 634                         path->slots[0]++;
 635                         new_key.offset = start;
 636                         btrfs_set_item_key_safe(trans, root, path, &new_key);
 637
 638                         fi = btrfs_item_ptr(leaf, path->slots[0],
 639                                             struct btrfs_file_extent_item);
 640                         btrfs_set_file_extent_num_bytes(leaf, fi,
 641                                                         other_end - start);
 642                         btrfs_set_file_extent_offset(leaf, fi,
 643                                                      start - orig_offset);
 644                         btrfs_mark_buffer_dirty(leaf);
 645                         goto out;
 646                 }
 647         }
 648
 649         while (start > key.offset || end < extent_end) {
 650                 if (key.offset == start)
 651                         split = end;
 652
 653                 new_key.offset = split;
 654                 ret = btrfs_duplicate_item(trans, root, path, &new_key);
 655                 if (ret == -EAGAIN) {
 656                         btrfs_release_path(root, path);
 657                         goto again;
 658                 }
 659                 BUG_ON(ret < 0);
 660
 661                 leaf = path->nodes[0];
 662                 fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
 663                                     struct btrfs_file_extent_item);
 664                 btrfs_set_file_extent_num_bytes(leaf, fi,
 665                                                 split - key.offset);
 666
 667                 fi = btrfs_item_ptr(leaf, path->slots[0],
 668                                     struct btrfs_file_extent_item);
 669
 670                 btrfs_set_file_extent_offset(leaf, fi, split - orig_offset);
 671                 btrfs_set_file_extent_num_bytes(leaf, fi,
 672                                                 extent_end - split);
 673                 btrfs_mark_buffer_dirty(leaf);
 674
 675                 ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
 676                                            root->root_key.objectid,
 677                                            inode->i_ino, orig_offset);
 678                 BUG_ON(ret);
 679
 680                 if (split == start) {
 681                         key.offset = start;
 682                 } else {
 683                         BUG_ON(start != key.offset);
 684                         path->slots[0]--;
 685                         extent_end = end;
 686                 }
 687                 recow = 1;
 688         }
 689
 690         other_start = end;
 691         other_end = 0;
 692         if (extent_mergeable(leaf, path->slots[0] + 1,
 693                              inode->i_ino, bytenr, orig_offset,
 694                              &other_start, &other_end)) {
 695                 if (recow) {
 696                         btrfs_release_path(root, path);
 697                         goto again;
 698                 }
 699                 extent_end = other_end;
 700                 del_slot = path->slots[0] + 1;
 701                 del_nr++;
 702                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
 703                                         0, root->root_key.objectid,
 704                                         inode->i_ino, orig_offset);
 705                 BUG_ON(ret);
 706         }
 707         other_start = 0;
 708         other_end = start;
 709         if (extent_mergeable(leaf, path->slots[0] - 1,
 710                              inode->i_ino, bytenr, orig_offset,
 711                              &other_start, &other_end)) {
 712                 if (recow) {
 713                         btrfs_release_path(root, path);
 714                         goto again;
 715                 }
 716                 key.offset = other_start;
 717                 del_slot = path->slots[0];
 718                 del_nr++;
 719                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
 720                                         0, root->root_key.objectid,
 721                                         inode->i_ino, orig_offset);
 722                 BUG_ON(ret);
 723         }
 724         if (del_nr == 0) {
 725                 fi = btrfs_item_ptr(leaf, path->slots[0],
 726                            struct btrfs_file_extent_item);
 727                 btrfs_set_file_extent_type(leaf, fi,
 728                                            BTRFS_FILE_EXTENT_REG);
 729                 btrfs_mark_buffer_dirty(leaf);
 730         } else {
 731                 fi = btrfs_item_ptr(leaf, del_slot - 1,
 732                            struct btrfs_file_extent_item);
 733                 btrfs_set_file_extent_type(leaf, fi,
 734                                            BTRFS_FILE_EXTENT_REG);
 735                 btrfs_set_file_extent_num_bytes(leaf, fi,
 736                                                 extent_end - key.offset);
 737                 btrfs_mark_buffer_dirty(leaf);
 738
 739                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
 740                 BUG_ON(ret);
 741         }
 742 out:
 743         btrfs_free_path(path);
 744         return 0;
 745 }
 746
 747 /*
 748  * this gets pages into the page cache and locks them down, it also properly
 749  * waits for data=ordered extents to finish before allowing the pages to be
 750  * modified.
 751  */
 752 static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
 753                          struct page **pages, size_t num_pages,
 754                          loff_t pos, unsigned long first_index,
 755                          unsigned long last_index, size_t write_bytes)
 756 {
 757         struct extent_state *cached_state = NULL;
 758         int i;
 759         unsigned long index = pos >> PAGE_CACHE_SHIFT;
 760         struct inode *inode = fdentry(file)->d_inode;
 761         int err = 0;
 762         u64 start_pos;
 763         u64 last_pos;
 764
 765         start_pos = pos & ~((u64)root->sectorsize - 1);
 766         last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
 767
 768         if (start_pos > inode->i_size) {
 769                 err = btrfs_cont_expand(inode, start_pos);
 770                 if (err)
 771                         return err;
 772         }
 773
 774         memset(pages, 0, num_pages * sizeof(struct page *));
 775 again:
 776         for (i = 0; i < num_pages; i++) {
 777                 pages[i] = grab_cache_page(inode->i_mapping, index + i);
 778                 if (!pages[i]) {
 779                         err = -ENOMEM;
 780                         BUG_ON(1);
 781                 }
 782                 wait_on_page_writeback(pages[i]);
 783         }
 784         if (start_pos < inode->i_size) {
 785                 struct btrfs_ordered_extent *ordered;
 786                 lock_extent_bits(&BTRFS_I(inode)->io_tree,
 787                                  start_pos, last_pos - 1, 0, &cached_state,
 788                                  GFP_NOFS);
 789                 ordered = btrfs_lookup_first_ordered_extent(inode,
 790                                                             last_pos - 1);
 791                 if (ordered &&
 792                     ordered->file_offset + ordered->len > start_pos &&
 793                     ordered->file_offset < last_pos) {
 794                         btrfs_put_ordered_extent(ordered);
 795                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
 796                                              start_pos, last_pos - 1,
 797                                              &cached_state, GFP_NOFS);
 798                         for (i = 0; i < num_pages; i++) {
 799                                 unlock_page(pages[i]);
 800                                 page_cache_release(pages[i]);
 801                         }
 802                         btrfs_wait_ordered_range(inode, start_pos,
 803                                                  last_pos - start_pos);
 804                         goto again;
 805                 }
 806                 if (ordered)
 807                         btrfs_put_ordered_extent(ordered);
 808
 809                 clear_extent_bit(&BTRFS_I(inode)->io_tree, start_pos,
 810                                   last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC |
 811                                   EXTENT_DO_ACCOUNTING, 0, 0, &cached_state,
 812                                   GFP_NOFS);
 813                 unlock_extent_cached(&BTRFS_I(inode)->io_tree,
 814                                      start_pos, last_pos - 1, &cached_state,
 815                                      GFP_NOFS);
 816         }
 817         for (i = 0; i < num_pages; i++) {
 818                 clear_page_dirty_for_io(pages[i]);
 819                 set_page_extent_mapped(pages[i]);
 820                 WARN_ON(!PageLocked(pages[i]));
 821         }
 822         return 0;
 823 }
 824
 825 static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
 826                                 size_t count, loff_t *ppos)
 827 {
 828         loff_t pos;
 829         loff_t start_pos;
 830         ssize_t num_written = 0;
 831         ssize_t err = 0;
 832         int ret = 0;
 833         struct inode *inode = fdentry(file)->d_inode;
 834         struct btrfs_root *root = BTRFS_I(inode)->root;
 835         struct page **pages = NULL;
 836         int nrptrs;
 837         struct page *pinned[2];
 838         unsigned long first_index;
 839         unsigned long last_index;
 840         int will_write;
 841
 842         will_write = ((file->f_flags & O_DSYNC) || IS_SYNC(inode) ||
 843                       (file->f_flags & O_DIRECT));
 844
 845         nrptrs = min((count + PAGE_CACHE_SIZE - 1) / PAGE_CACHE_SIZE,
 846                      PAGE_CACHE_SIZE / (sizeof(struct page *)));
 847         pinned[0] = NULL;
 848         pinned[1] = NULL;
 849
 850         pos = *ppos;
 851         start_pos = pos;
 852
 853         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
 854
 855         /* do the reserve before the mutex lock in case we have to do some
 856          * flushing.  We wouldn't deadlock, but this is more polite.
 857          */
 858         err = btrfs_reserve_metadata_for_delalloc(root, inode, 1);
 859         if (err)
 860                 goto out_nolock;
 861
 862         mutex_lock(&inode->i_mutex);
 863
 864         current->backing_dev_info = inode->i_mapping->backing_dev_info;
 865         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
 866         if (err)
 867                 goto out;
 868
 869         if (count == 0)
 870                 goto out;
 871
 872         err = file_remove_suid(file);
 873         if (err)
 874                 goto out;
 875
 876         file_update_time(file);
 877
 878         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
 879
 880         /* generic_write_checks can change our pos */
 881         start_pos = pos;
 882
 883         BTRFS_I(inode)->sequence++;
 884         first_index = pos >> PAGE_CACHE_SHIFT;
 885         last_index = (pos + count) >> PAGE_CACHE_SHIFT;
 886
 887         /*
 888          * there are lots of better ways to do this, but this code
 889          * makes sure the first and last page in the file range are
 890          * up to date and ready for cow
 891          */
 892         if ((pos & (PAGE_CACHE_SIZE - 1))) {
 893                 pinned[0] = grab_cache_page(inode->i_mapping, first_index);
 894                 if (!PageUptodate(pinned[0])) {
 895                         ret = btrfs_readpage(NULL, pinned[0]);
 896                         BUG_ON(ret);
 897                         wait_on_page_locked(pinned[0]);
 898                 } else {
 899                         unlock_page(pinned[0]);
 900                 }
 901         }
 902         if ((pos + count) & (PAGE_CACHE_SIZE - 1)) {
 903                 pinned[1] = grab_cache_page(inode->i_mapping, last_index);
 904                 if (!PageUptodate(pinned[1])) {
 905                         ret = btrfs_readpage(NULL, pinned[1]);
 906                         BUG_ON(ret);
 907                         wait_on_page_locked(pinned[1]);
 908                 } else {
 909                         unlock_page(pinned[1]);
 910                 }
 911         }
 912
 913         while (count > 0) {
 914                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
 915                 size_t write_bytes = min(count, nrptrs *
 916                                         (size_t)PAGE_CACHE_SIZE -
 917                                          offset);
 918                 size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
 919                                         PAGE_CACHE_SHIFT;
 920
 921                 WARN_ON(num_pages > nrptrs);
 922                 memset(pages, 0, sizeof(struct page *) * nrptrs);
 923
 924                 ret = btrfs_check_data_free_space(root, inode, write_bytes);
 925                 if (ret)
 926                         goto out;
 927
 928                 ret = prepare_pages(root, file, pages, num_pages,
 929                                     pos, first_index, last_index,
 930                                     write_bytes);
 931                 if (ret) {
 932                         btrfs_free_reserved_data_space(root, inode,
 933                                                        write_bytes);
 934                         goto out;
 935                 }
 936
 937                 ret = btrfs_copy_from_user(pos, num_pages,
 938                                            write_bytes, pages, buf);
 939                 if (ret) {
 940                         btrfs_free_reserved_data_space(root, inode,
 941                                                        write_bytes);
 942                         btrfs_drop_pages(pages, num_pages);
 943                         goto out;
 944                 }
 945
 946                 ret = dirty_and_release_pages(NULL, root, file, pages,
 947                                               num_pages, pos, write_bytes);
 948                 btrfs_drop_pages(pages, num_pages);
 949                 if (ret) {
 950                         btrfs_free_reserved_data_space(root, inode,
 951                                                        write_bytes);
 952                         goto out;
 953                 }
 954
 955                 if (will_write) {
 956                         filemap_fdatawrite_range(inode->i_mapping, pos,
 957                                                  pos + write_bytes - 1);
 958                 } else {
 959                         balance_dirty_pages_ratelimited_nr(inode->i_mapping,
 960                                                            num_pages);
 961                         if (num_pages <
 962                             (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
 963                                 btrfs_btree_balance_dirty(root, 1);
 964                         btrfs_throttle(root);
 965                 }
 966
 967                 buf += write_bytes;
 968                 count -= write_bytes;
 969                 pos += write_bytes;
 970                 num_written += write_bytes;
 971
 972                 cond_resched();
 973         }
 974 out:
 975         mutex_unlock(&inode->i_mutex);
 976         if (ret)
 977                 err = ret;
 978         btrfs_unreserve_metadata_for_delalloc(root, inode, 1);
 979
 980 out_nolock:
 981         kfree(pages);
 982         if (pinned[0])
 983                 page_cache_release(pinned[0]);
 984         if (pinned[1])
 985                 page_cache_release(pinned[1]);
 986         *ppos = pos;
 987
 988         /*
 989          * we want to make sure fsync finds this change
 990          * but we haven't joined a transaction running right now.
 991          *
 992          * Later on, someone is sure to update the inode and get the
 993          * real transid recorded.
 994          *
 995          * We set last_trans now to the fs_info generation + 1,
 996          * this will either be one more than the running transaction
 997          * or the generation used for the next transaction if there isn't
 998          * one running right now.
 999          */
1000         BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
1001
1002         if (num_written > 0 && will_write) {
1003                 struct btrfs_trans_handle *trans;
1004
1005                 err = btrfs_wait_ordered_range(inode, start_pos, num_written);
1006                 if (err)
1007                         num_written = err;
1008
1009                 if ((file->f_flags & O_DSYNC) || IS_SYNC(inode)) {
1010                         trans = btrfs_start_transaction(root, 1);
1011                         ret = btrfs_log_dentry_safe(trans, root,
1012                                                     file->f_dentry);
1013                         if (ret == 0) {
1014                                 ret = btrfs_sync_log(trans, root);
1015                                 if (ret == 0)
1016                                         btrfs_end_transaction(trans, root);
1017                                 else
1018                                         btrfs_commit_transaction(trans, root);
1019                         } else if (ret != BTRFS_NO_LOG_SYNC) {
1020                                 btrfs_commit_transaction(trans, root);
1021                         } else {
1022                                 btrfs_end_transaction(trans, root);
1023                         }
1024                 }
1025                 if (file->f_flags & O_DIRECT) {
1026                         invalidate_mapping_pages(inode->i_mapping,
1027                               start_pos >> PAGE_CACHE_SHIFT,
1028                              (start_pos + num_written - 1) >> PAGE_CACHE_SHIFT);
1029                 }
1030         }
1031         current->backing_dev_info = NULL;
1032         return num_written ? num_written : err;
1033 }
1034
1035 int btrfs_release_file(struct inode *inode, struct file *filp)
1036 {
1037         /*
1038          * ordered_data_close is set by settattr when we are about to truncate
1039          * a file from a non-zero size to a zero size.  This tries to
1040          * flush down new bytes that may have been written if the
1041          * application were using truncate to replace a file in place.
1042          */
1043         if (BTRFS_I(inode)->ordered_data_close) {
1044                 BTRFS_I(inode)->ordered_data_close = 0;
1045                 btrfs_add_ordered_operation(NULL, BTRFS_I(inode)->root, inode);
1046                 if (inode->i_size > BTRFS_ORDERED_OPERATIONS_FLUSH_LIMIT)
1047                         filemap_flush(inode->i_mapping);
1048         }
1049         if (filp->private_data)
1050                 btrfs_ioctl_trans_end(filp);
1051         return 0;
1052 }
1053
1054 /*
1055  * fsync call for both files and directories.  This logs the inode into
1056  * the tree log instead of forcing full commits whenever possible.
1057  *
1058  * It needs to call filemap_fdatawait so that all ordered extent updates are
1059  * in the metadata btree are up to date for copying to the log.
1060  *
1061  * It drops the inode mutex before doing the tree log commit.  This is an
1062  * important optimization for directories because holding the mutex prevents
1063  * new operations on the dir while we write to disk.
1064  */
1065 int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
1066 {
1067         struct inode *inode = dentry->d_inode;
1068         struct btrfs_root *root = BTRFS_I(inode)->root;
1069         int ret = 0;
1070         struct btrfs_trans_handle *trans;
1071
1072
1073         /* we wait first, since the writeback may change the inode */
1074         root->log_batch++;
1075         /* the VFS called filemap_fdatawrite for us */
1076         btrfs_wait_ordered_range(inode, 0, (u64)-1);
1077         root->log_batch++;
1078
1079         /*
1080          * check the transaction that last modified this inode
1081          * and see if its already been committed
1082          */
1083         if (!BTRFS_I(inode)->last_trans)
1084                 goto out;
1085
1086         /*
1087          * if the last transaction that changed this file was before
1088          * the current transaction, we can bail out now without any
1089          * syncing
1090          */
1091         mutex_lock(&root->fs_info->trans_mutex);
1092         if (BTRFS_I(inode)->last_trans <=
1093             root->fs_info->last_trans_committed) {
1094                 BTRFS_I(inode)->last_trans = 0;
1095                 mutex_unlock(&root->fs_info->trans_mutex);
1096                 goto out;
1097         }
1098         mutex_unlock(&root->fs_info->trans_mutex);
1099
1100         /*
1101          * ok we haven't committed the transaction yet, lets do a commit
1102          */
1103         if (file && file->private_data)
1104                 btrfs_ioctl_trans_end(file);
1105
1106         trans = btrfs_start_transaction(root, 1);
1107         if (!trans) {
1108                 ret = -ENOMEM;
1109                 goto out;
1110         }
1111
1112         ret = btrfs_log_dentry_safe(trans, root, dentry);
1113         if (ret < 0)
1114                 goto out;
1115
1116         /* we've logged all the items and now have a consistent
1117          * version of the file in the log.  It is possible that
1118          * someone will come in and modify the file, but that's
1119          * fine because the log is consistent on disk, and we
1120          * have references to all of the file's extents
1121          *
1122          * It is possible that someone will come in and log the
1123          * file again, but that will end up using the synchronization
1124          * inside btrfs_sync_log to keep things safe.
1125          */
1126         mutex_unlock(&dentry->d_inode->i_mutex);
1127
1128         if (ret != BTRFS_NO_LOG_SYNC) {
1129                 if (ret > 0) {
1130                         ret = btrfs_commit_transaction(trans, root);
1131                 } else {
1132                         ret = btrfs_sync_log(trans, root);
1133                         if (ret == 0)
1134                                 ret = btrfs_end_transaction(trans, root);
1135                         else
1136                                 ret = btrfs_commit_transaction(trans, root);
1137                 }
1138         } else {
1139                 ret = btrfs_end_transaction(trans, root);
1140         }
1141         mutex_lock(&dentry->d_inode->i_mutex);
1142 out:
1143         return ret > 0 ? -EIO : ret;
1144 }
1145
1146 static const struct vm_operations_struct btrfs_file_vm_ops = {
1147         .fault          = filemap_fault,
1148         .page_mkwrite   = btrfs_page_mkwrite,
1149 };
1150
1151 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
1152 {
1153         vma->vm_ops = &btrfs_file_vm_ops;
1154         file_accessed(filp);
1155         return 0;
1156 }
1157
1158 const struct file_operations btrfs_file_operations = {
1159         .llseek         = generic_file_llseek,
1160         .read           = do_sync_read,
1161         .aio_read       = generic_file_aio_read,
1162         .splice_read    = generic_file_splice_read,
1163         .write          = btrfs_file_write,
1164         .mmap           = btrfs_file_mmap,
1165         .open           = generic_file_open,
1166         .release        = btrfs_release_file,
1167         .fsync          = btrfs_sync_file,
1168         .unlocked_ioctl = btrfs_ioctl,
1169 #ifdef CONFIG_COMPAT
1170         .compat_ioctl   = btrfs_ioctl,
1171 #endif
1172 };