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 <linux/slab.h>
  32 #include "ctree.h"
  33 #include "disk-io.h"
  34 #include "transaction.h"
  35 #include "btrfs_inode.h"
  36 #include "ioctl.h"
  37 #include "print-tree.h"
  38 #include "tree-log.h"
  39 #include "locking.h"
  40 #include "compat.h"
  41
  42
  43 /* simple helper to fault in pages and copy.  This should go away
  44  * and be replaced with calls into generic code.
  45  */
  46 static noinline int btrfs_copy_from_user(loff_t pos, int num_pages,
  47                                          int write_bytes,
  48                                          struct page **prepared_pages,
  49                                          const char __user *buf)
  50 {
  51         long page_fault = 0;
  52         int i;
  53         int offset = pos & (PAGE_CACHE_SIZE - 1);
  54
  55         for (i = 0; i < num_pages && write_bytes > 0; i++, offset = 0) {
  56                 size_t count = min_t(size_t,
  57                                      PAGE_CACHE_SIZE - offset, write_bytes);
  58                 struct page *page = prepared_pages[i];
  59                 fault_in_pages_readable(buf, count);
  60
  61                 /* Copy data from userspace to the current page */
  62                 kmap(page);
  63                 page_fault = __copy_from_user(page_address(page) + offset,
  64                                               buf, count);
  65                 /* Flush processor's dcache for this page */
  66                 flush_dcache_page(page);
  67                 kunmap(page);
  68                 buf += count;
  69                 write_bytes -= count;
  70
  71                 if (page_fault)
  72                         break;
  73         }
  74         return page_fault ? -EFAULT : 0;
  75 }
  76
  77 /*
  78  * unlocks pages after btrfs_file_write is done with them
  79  */
  80 static noinline void btrfs_drop_pages(struct page **pages, size_t num_pages)
  81 {
  82         size_t i;
  83         for (i = 0; i < num_pages; i++) {
  84                 if (!pages[i])
  85                         break;
  86                 /* page checked is some magic around finding pages that
  87                  * have been modified without going through btrfs_set_page_dirty
  88                  * clear it here
  89                  */
  90                 ClearPageChecked(pages[i]);
  91                 unlock_page(pages[i]);
  92                 mark_page_accessed(pages[i]);
  93                 page_cache_release(pages[i]);
  94         }
  95 }
  96
  97 /*
  98  * after copy_from_user, pages need to be dirtied and we need to make
  99  * sure holes are created between the current EOF and the start of
 100  * any next extents (if required).
 101  *
 102  * this also makes the decision about creating an inline extent vs
 103  * doing real data extents, marking pages dirty and delalloc as required.
 104  */
 105 static noinline int dirty_and_release_pages(struct btrfs_trans_handle *trans,
 106                                    struct btrfs_root *root,
 107                                    struct file *file,
 108                                    struct page **pages,
 109                                    size_t num_pages,
 110                                    loff_t pos,
 111                                    size_t write_bytes)
 112 {
 113         int err = 0;
 114         int i;
 115         struct inode *inode = fdentry(file)->d_inode;
 116         u64 num_bytes;
 117         u64 start_pos;
 118         u64 end_of_last_block;
 119         u64 end_pos = pos + write_bytes;
 120         loff_t isize = i_size_read(inode);
 121
 122         start_pos = pos & ~((u64)root->sectorsize - 1);
 123         num_bytes = (write_bytes + pos - start_pos +
 124                     root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
 125
 126         end_of_last_block = start_pos + num_bytes - 1;
 127         err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block,
 128                                         NULL);
 129         if (err)
 130                 return err;
 131
 132         for (i = 0; i < num_pages; i++) {
 133                 struct page *p = pages[i];
 134                 SetPageUptodate(p);
 135                 ClearPageChecked(p);
 136                 set_page_dirty(p);
 137         }
 138         if (end_pos > isize) {
 139                 i_size_write(inode, end_pos);
 140                 /* we've only changed i_size in ram, and we haven't updated
 141                  * the disk i_size.  There is no need to log the inode
 142                  * at this time.
 143                  */
 144         }
 145         return err;
 146 }
 147
 148 /*
 149  * this drops all the extents in the cache that intersect the range
 150  * [start, end].  Existing extents are split as required.
 151  */
 152 int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
 153                             int skip_pinned)
 154 {
 155         struct extent_map *em;
 156         struct extent_map *split = NULL;
 157         struct extent_map *split2 = NULL;
 158         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
 159         u64 len = end - start + 1;
 160         int ret;
 161         int testend = 1;
 162         unsigned long flags;
 163         int compressed = 0;
 164
 165         WARN_ON(end < start);
 166         if (end == (u64)-1) {
 167                 len = (u64)-1;
 168                 testend = 0;
 169         }
 170         while (1) {
 171                 if (!split)
 172                         split = alloc_extent_map(GFP_NOFS);
 173                 if (!split2)
 174                         split2 = alloc_extent_map(GFP_NOFS);
 175
 176                 write_lock(&em_tree->lock);
 177                 em = lookup_extent_mapping(em_tree, start, len);
 178                 if (!em) {
 179                         write_unlock(&em_tree->lock);
 180                         break;
 181                 }
 182                 flags = em->flags;
 183                 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
 184                         if (testend && em->start + em->len >= start + len) {
 185                                 free_extent_map(em);
 186                                 write_unlock(&em_tree->lock);
 187                                 break;
 188                         }
 189                         start = em->start + em->len;
 190                         if (testend)
 191                                 len = start + len - (em->start + em->len);
 192                         free_extent_map(em);
 193                         write_unlock(&em_tree->lock);
 194                         continue;
 195                 }
 196                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 197                 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
 198                 remove_extent_mapping(em_tree, em);
 199
 200                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 201                     em->start < start) {
 202                         split->start = em->start;
 203                         split->len = start - em->start;
 204                         split->orig_start = em->orig_start;
 205                         split->block_start = em->block_start;
 206
 207                         if (compressed)
 208                                 split->block_len = em->block_len;
 209                         else
 210                                 split->block_len = split->len;
 211
 212                         split->bdev = em->bdev;
 213                         split->flags = flags;
 214                         ret = add_extent_mapping(em_tree, split);
 215                         BUG_ON(ret);
 216                         free_extent_map(split);
 217                         split = split2;
 218                         split2 = NULL;
 219                 }
 220                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 221                     testend && em->start + em->len > start + len) {
 222                         u64 diff = start + len - em->start;
 223
 224                         split->start = start + len;
 225                         split->len = em->start + em->len - (start + len);
 226                         split->bdev = em->bdev;
 227                         split->flags = flags;
 228
 229                         if (compressed) {
 230                                 split->block_len = em->block_len;
 231                                 split->block_start = em->block_start;
 232                                 split->orig_start = em->orig_start;
 233                         } else {
 234                                 split->block_len = split->len;
 235                                 split->block_start = em->block_start + diff;
 236                                 split->orig_start = split->start;
 237                         }
 238
 239                         ret = add_extent_mapping(em_tree, split);
 240                         BUG_ON(ret);
 241                         free_extent_map(split);
 242                         split = NULL;
 243                 }
 244                 write_unlock(&em_tree->lock);
 245
 246                 /* once for us */
 247                 free_extent_map(em);
 248                 /* once for the tree*/
 249                 free_extent_map(em);
 250         }
 251         if (split)
 252                 free_extent_map(split);
 253         if (split2)
 254                 free_extent_map(split2);
 255         return 0;
 256 }
 257
 258 /*
 259  * this is very complex, but the basic idea is to drop all extents
 260  * in the range start - end.  hint_block is filled in with a block number
 261  * that would be a good hint to the block allocator for this file.
 262  *
 263  * If an extent intersects the range but is not entirely inside the range
 264  * it is either truncated or split.  Anything entirely inside the range
 265  * is deleted from the tree.
 266  */
 267 int btrfs_drop_extents(struct btrfs_trans_handle *trans, struct inode *inode,
 268                        u64 start, u64 end, u64 *hint_byte, int drop_cache)
 269 {
 270         struct btrfs_root *root = BTRFS_I(inode)->root;
 271         struct extent_buffer *leaf;
 272         struct btrfs_file_extent_item *fi;
 273         struct btrfs_path *path;
 274         struct btrfs_key key;
 275         struct btrfs_key new_key;
 276         u64 search_start = start;
 277         u64 disk_bytenr = 0;
 278         u64 num_bytes = 0;
 279         u64 extent_offset = 0;
 280         u64 extent_end = 0;
 281         int del_nr = 0;
 282         int del_slot = 0;
 283         int extent_type;
 284         int recow;
 285         int ret;
 286
 287         if (drop_cache)
 288                 btrfs_drop_extent_cache(inode, start, end - 1, 0);
 289
 290         path = btrfs_alloc_path();
 291         if (!path)
 292                 return -ENOMEM;
 293
 294         while (1) {
 295                 recow = 0;
 296                 ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
 297                                                search_start, -1);
 298                 if (ret < 0)
 299                         break;
 300                 if (ret > 0 && path->slots[0] > 0 && search_start == start) {
 301                         leaf = path->nodes[0];
 302                         btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 303                         if (key.objectid == inode->i_ino &&
 304                             key.type == BTRFS_EXTENT_DATA_KEY)
 305                                 path->slots[0]--;
 306                 }
 307                 ret = 0;
 308 next_slot:
 309                 leaf = path->nodes[0];
 310                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 311                         BUG_ON(del_nr > 0);
 312                         ret = btrfs_next_leaf(root, path);
 313                         if (ret < 0)
 314                                 break;
 315                         if (ret > 0) {
 316                                 ret = 0;
 317                                 break;
 318                         }
 319                         leaf = path->nodes[0];
 320                         recow = 1;
 321                 }
 322
 323                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 324                 if (key.objectid > inode->i_ino ||
 325                     key.type > BTRFS_EXTENT_DATA_KEY || key.offset >= end)
 326                         break;
 327
 328                 fi = btrfs_item_ptr(leaf, path->slots[0],
 329                                     struct btrfs_file_extent_item);
 330                 extent_type = btrfs_file_extent_type(leaf, fi);
 331
 332                 if (extent_type == BTRFS_FILE_EXTENT_REG ||
 333                     extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
 334                         disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 335                         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
 336                         extent_offset = btrfs_file_extent_offset(leaf, fi);
 337                         extent_end = key.offset +
 338                                 btrfs_file_extent_num_bytes(leaf, fi);
 339                 } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 340                         extent_end = key.offset +
 341                                 btrfs_file_extent_inline_len(leaf, fi);
 342                 } else {
 343                         WARN_ON(1);
 344                         extent_end = search_start;
 345                 }
 346
 347                 if (extent_end <= search_start) {
 348                         path->slots[0]++;
 349                         goto next_slot;
 350                 }
 351
 352                 search_start = max(key.offset, start);
 353                 if (recow) {
 354                         btrfs_release_path(root, path);
 355                         continue;
 356                 }
 357
 358                 /*
 359                  *     | - range to drop - |
 360                  *  | -------- extent -------- |
 361                  */
 362                 if (start > key.offset && end < extent_end) {
 363                         BUG_ON(del_nr > 0);
 364                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 365
 366                         memcpy(&new_key, &key, sizeof(new_key));
 367                         new_key.offset = start;
 368                         ret = btrfs_duplicate_item(trans, root, path,
 369                                                    &new_key);
 370                         if (ret == -EAGAIN) {
 371                                 btrfs_release_path(root, path);
 372                                 continue;
 373                         }
 374                         if (ret < 0)
 375                                 break;
 376
 377                         leaf = path->nodes[0];
 378                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
 379                                             struct btrfs_file_extent_item);
 380                         btrfs_set_file_extent_num_bytes(leaf, fi,
 381                                                         start - key.offset);
 382
 383                         fi = btrfs_item_ptr(leaf, path->slots[0],
 384                                             struct btrfs_file_extent_item);
 385
 386                         extent_offset += start - key.offset;
 387                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
 388                         btrfs_set_file_extent_num_bytes(leaf, fi,
 389                                                         extent_end - start);
 390                         btrfs_mark_buffer_dirty(leaf);
 391
 392                         if (disk_bytenr > 0) {
 393                                 ret = btrfs_inc_extent_ref(trans, root,
 394                                                 disk_bytenr, num_bytes, 0,
 395                                                 root->root_key.objectid,
 396                                                 new_key.objectid,
 397                                                 start - extent_offset);
 398                                 BUG_ON(ret);
 399                                 *hint_byte = disk_bytenr;
 400                         }
 401                         key.offset = start;
 402                 }
 403                 /*
 404                  *  | ---- range to drop ----- |
 405                  *      | -------- extent -------- |
 406                  */
 407                 if (start <= key.offset && end < extent_end) {
 408                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 409
 410                         memcpy(&new_key, &key, sizeof(new_key));
 411                         new_key.offset = end;
 412                         btrfs_set_item_key_safe(trans, root, path, &new_key);
 413
 414                         extent_offset += end - key.offset;
 415                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
 416                         btrfs_set_file_extent_num_bytes(leaf, fi,
 417                                                         extent_end - end);
 418                         btrfs_mark_buffer_dirty(leaf);
 419                         if (disk_bytenr > 0) {
 420                                 inode_sub_bytes(inode, end - key.offset);
 421                                 *hint_byte = disk_bytenr;
 422                         }
 423                         break;
 424                 }
 425
 426                 search_start = extent_end;
 427                 /*
 428                  *       | ---- range to drop ----- |
 429                  *  | -------- extent -------- |
 430                  */
 431                 if (start > key.offset && end >= extent_end) {
 432                         BUG_ON(del_nr > 0);
 433                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 434
 435                         btrfs_set_file_extent_num_bytes(leaf, fi,
 436                                                         start - key.offset);
 437                         btrfs_mark_buffer_dirty(leaf);
 438                         if (disk_bytenr > 0) {
 439                                 inode_sub_bytes(inode, extent_end - start);
 440                                 *hint_byte = disk_bytenr;
 441                         }
 442                         if (end == extent_end)
 443                                 break;
 444
 445                         path->slots[0]++;
 446                         goto next_slot;
 447                 }
 448
 449                 /*
 450                  *  | ---- range to drop ----- |
 451                  *    | ------ extent ------ |
 452                  */
 453                 if (start <= key.offset && end >= extent_end) {
 454                         if (del_nr == 0) {
 455                                 del_slot = path->slots[0];
 456                                 del_nr = 1;
 457                         } else {
 458                                 BUG_ON(del_slot + del_nr != path->slots[0]);
 459                                 del_nr++;
 460                         }
 461
 462                         if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 463                                 inode_sub_bytes(inode,
 464                                                 extent_end - key.offset);
 465                                 extent_end = ALIGN(extent_end,
 466                                                    root->sectorsize);
 467                         } else if (disk_bytenr > 0) {
 468                                 ret = btrfs_free_extent(trans, root,
 469                                                 disk_bytenr, num_bytes, 0,
 470                                                 root->root_key.objectid,
 471                                                 key.objectid, key.offset -
 472                                                 extent_offset);
 473                                 BUG_ON(ret);
 474                                 inode_sub_bytes(inode,
 475                                                 extent_end - key.offset);
 476                                 *hint_byte = disk_bytenr;
 477                         }
 478
 479                         if (end == extent_end)
 480                                 break;
 481
 482                         if (path->slots[0] + 1 < btrfs_header_nritems(leaf)) {
 483                                 path->slots[0]++;
 484                                 goto next_slot;
 485                         }
 486
 487                         ret = btrfs_del_items(trans, root, path, del_slot,
 488                                               del_nr);
 489                         BUG_ON(ret);
 490
 491                         del_nr = 0;
 492                         del_slot = 0;
 493
 494                         btrfs_release_path(root, path);
 495                         continue;
 496                 }
 497
 498                 BUG_ON(1);
 499         }
 500
 501         if (del_nr > 0) {
 502                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
 503                 BUG_ON(ret);
 504         }
 505
 506         btrfs_free_path(path);
 507         return ret;
 508 }
 509
 510 static int extent_mergeable(struct extent_buffer *leaf, int slot,
 511                             u64 objectid, u64 bytenr, u64 orig_offset,
 512                             u64 *start, u64 *end)
 513 {
 514         struct btrfs_file_extent_item *fi;
 515         struct btrfs_key key;
 516         u64 extent_end;
 517
 518         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
 519                 return 0;
 520
 521         btrfs_item_key_to_cpu(leaf, &key, slot);
 522         if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
 523                 return 0;
 524
 525         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
 526         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
 527             btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
 528             btrfs_file_extent_offset(leaf, fi) != key.offset - orig_offset ||
 529             btrfs_file_extent_compression(leaf, fi) ||
 530             btrfs_file_extent_encryption(leaf, fi) ||
 531             btrfs_file_extent_other_encoding(leaf, fi))
 532                 return 0;
 533
 534         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 535         if ((*start && *start != key.offset) || (*end && *end != extent_end))
 536                 return 0;
 537
 538         *start = key.offset;
 539         *end = extent_end;
 540         return 1;
 541 }
 542
 543 /*
 544  * Mark extent in the range start - end as written.
 545  *
 546  * This changes extent type from 'pre-allocated' to 'regular'. If only
 547  * part of extent is marked as written, the extent will be split into
 548  * two or three.
 549  */
 550 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
 551                               struct inode *inode, u64 start, u64 end)
 552 {
 553         struct btrfs_root *root = BTRFS_I(inode)->root;
 554         struct extent_buffer *leaf;
 555         struct btrfs_path *path;
 556         struct btrfs_file_extent_item *fi;
 557         struct btrfs_key key;
 558         struct btrfs_key new_key;
 559         u64 bytenr;
 560         u64 num_bytes;
 561         u64 extent_end;
 562         u64 orig_offset;
 563         u64 other_start;
 564         u64 other_end;
 565         u64 split;
 566         int del_nr = 0;
 567         int del_slot = 0;
 568         int recow;
 569         int ret;
 570
 571         btrfs_drop_extent_cache(inode, start, end - 1, 0);
 572
 573         path = btrfs_alloc_path();
 574         BUG_ON(!path);
 575 again:
 576         recow = 0;
 577         split = start;
 578         key.objectid = inode->i_ino;
 579         key.type = BTRFS_EXTENT_DATA_KEY;
 580         key.offset = split;
 581
 582         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 583         if (ret > 0 && path->slots[0] > 0)
 584                 path->slots[0]--;
 585
 586         leaf = path->nodes[0];
 587         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 588         BUG_ON(key.objectid != inode->i_ino ||
 589                key.type != BTRFS_EXTENT_DATA_KEY);
 590         fi = btrfs_item_ptr(leaf, path->slots[0],
 591                             struct btrfs_file_extent_item);
 592         BUG_ON(btrfs_file_extent_type(leaf, fi) !=
 593                BTRFS_FILE_EXTENT_PREALLOC);
 594         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 595         BUG_ON(key.offset > start || extent_end < end);
 596
 597         bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 598         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
 599         orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
 600         memcpy(&new_key, &key, sizeof(new_key));
 601
 602         if (start == key.offset && end < extent_end) {
 603                 other_start = 0;
 604                 other_end = start;
 605                 if (extent_mergeable(leaf, path->slots[0] - 1,
 606                                      inode->i_ino, bytenr, orig_offset,
 607                                      &other_start, &other_end)) {
 608                         new_key.offset = end;
 609                         btrfs_set_item_key_safe(trans, root, path, &new_key);
 610                         fi = btrfs_item_ptr(leaf, path->slots[0],
 611                                             struct btrfs_file_extent_item);
 612                         btrfs_set_file_extent_num_bytes(leaf, fi,
 613                                                         extent_end - end);
 614                         btrfs_set_file_extent_offset(leaf, fi,
 615                                                      end - orig_offset);
 616                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
 617                                             struct btrfs_file_extent_item);
 618                         btrfs_set_file_extent_num_bytes(leaf, fi,
 619                                                         end - other_start);
 620                         btrfs_mark_buffer_dirty(leaf);
 621                         goto out;
 622                 }
 623         }
 624
 625         if (start > key.offset && end == extent_end) {
 626                 other_start = end;
 627                 other_end = 0;
 628                 if (extent_mergeable(leaf, path->slots[0] + 1,
 629                                      inode->i_ino, bytenr, orig_offset,
 630                                      &other_start, &other_end)) {
 631                         fi = btrfs_item_ptr(leaf, path->slots[0],
 632                                             struct btrfs_file_extent_item);
 633                         btrfs_set_file_extent_num_bytes(leaf, fi,
 634                                                         start - key.offset);
 635                         path->slots[0]++;
 636                         new_key.offset = start;
 637                         btrfs_set_item_key_safe(trans, root, path, &new_key);
 638
 639                         fi = btrfs_item_ptr(leaf, path->slots[0],
 640                                             struct btrfs_file_extent_item);
 641                         btrfs_set_file_extent_num_bytes(leaf, fi,
 642                                                         other_end - start);
 643                         btrfs_set_file_extent_offset(leaf, fi,
 644                                                      start - orig_offset);
 645                         btrfs_mark_buffer_dirty(leaf);
 646                         goto out;
 647                 }
 648         }
 649
 650         while (start > key.offset || end < extent_end) {
 651                 if (key.offset == start)
 652                         split = end;
 653
 654                 new_key.offset = split;
 655                 ret = btrfs_duplicate_item(trans, root, path, &new_key);
 656                 if (ret == -EAGAIN) {
 657                         btrfs_release_path(root, path);
 658                         goto again;
 659                 }
 660                 BUG_ON(ret < 0);
 661
 662                 leaf = path->nodes[0];
 663                 fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
 664                                     struct btrfs_file_extent_item);
 665                 btrfs_set_file_extent_num_bytes(leaf, fi,
 666                                                 split - key.offset);
 667
 668                 fi = btrfs_item_ptr(leaf, path->slots[0],
 669                                     struct btrfs_file_extent_item);
 670
 671                 btrfs_set_file_extent_offset(leaf, fi, split - orig_offset);
 672                 btrfs_set_file_extent_num_bytes(leaf, fi,
 673                                                 extent_end - split);
 674                 btrfs_mark_buffer_dirty(leaf);
 675
 676                 ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
 677                                            root->root_key.objectid,
 678                                            inode->i_ino, orig_offset);
 679                 BUG_ON(ret);
 680
 681                 if (split == start) {
 682                         key.offset = start;
 683                 } else {
 684                         BUG_ON(start != key.offset);
 685                         path->slots[0]--;
 686                         extent_end = end;
 687                 }
 688                 recow = 1;
 689         }
 690
 691         other_start = end;
 692         other_end = 0;
 693         if (extent_mergeable(leaf, path->slots[0] + 1,
 694                              inode->i_ino, bytenr, orig_offset,
 695                              &other_start, &other_end)) {
 696                 if (recow) {
 697                         btrfs_release_path(root, path);
 698                         goto again;
 699                 }
 700                 extent_end = other_end;
 701                 del_slot = path->slots[0] + 1;
 702                 del_nr++;
 703                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
 704                                         0, root->root_key.objectid,
 705                                         inode->i_ino, orig_offset);
 706                 BUG_ON(ret);
 707         }
 708         other_start = 0;
 709         other_end = start;
 710         if (extent_mergeable(leaf, path->slots[0] - 1,
 711                              inode->i_ino, bytenr, orig_offset,
 712                              &other_start, &other_end)) {
 713                 if (recow) {
 714                         btrfs_release_path(root, path);
 715                         goto again;
 716                 }
 717                 key.offset = other_start;
 718                 del_slot = path->slots[0];
 719                 del_nr++;
 720                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
 721                                         0, root->root_key.objectid,
 722                                         inode->i_ino, orig_offset);
 723                 BUG_ON(ret);
 724         }
 725         if (del_nr == 0) {
 726                 fi = btrfs_item_ptr(leaf, path->slots[0],
 727                            struct btrfs_file_extent_item);
 728                 btrfs_set_file_extent_type(leaf, fi,
 729                                            BTRFS_FILE_EXTENT_REG);
 730                 btrfs_mark_buffer_dirty(leaf);
 731         } else {
 732                 fi = btrfs_item_ptr(leaf, del_slot - 1,
 733                            struct btrfs_file_extent_item);
 734                 btrfs_set_file_extent_type(leaf, fi,
 735                                            BTRFS_FILE_EXTENT_REG);
 736                 btrfs_set_file_extent_num_bytes(leaf, fi,
 737                                                 extent_end - key.offset);
 738                 btrfs_mark_buffer_dirty(leaf);
 739
 740                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
 741                 BUG_ON(ret);
 742         }
 743 out:
 744         btrfs_free_path(path);
 745         return 0;
 746 }
 747
 748 /*
 749  * this gets pages into the page cache and locks them down, it also properly
 750  * waits for data=ordered extents to finish before allowing the pages to be
 751  * modified.
 752  */
 753 static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
 754                          struct page **pages, size_t num_pages,
 755                          loff_t pos, unsigned long first_index,
 756                          unsigned long last_index, size_t write_bytes)
 757 {
 758         struct extent_state *cached_state = NULL;
 759         int i;
 760         unsigned long index = pos >> PAGE_CACHE_SHIFT;
 761         struct inode *inode = fdentry(file)->d_inode;
 762         int err = 0;
 763         u64 start_pos;
 764         u64 last_pos;
 765
 766         start_pos = pos & ~((u64)root->sectorsize - 1);
 767         last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
 768
 769         if (start_pos > inode->i_size) {
 770                 err = btrfs_cont_expand(inode, start_pos);
 771                 if (err)
 772                         return err;
 773         }
 774
 775         memset(pages, 0, num_pages * sizeof(struct page *));
 776 again:
 777         for (i = 0; i < num_pages; i++) {
 778                 pages[i] = grab_cache_page(inode->i_mapping, index + i);
 779                 if (!pages[i]) {
 780                         err = -ENOMEM;
 781                         BUG_ON(1);
 782                 }
 783                 wait_on_page_writeback(pages[i]);
 784         }
 785         if (start_pos < inode->i_size) {
 786                 struct btrfs_ordered_extent *ordered;
 787                 lock_extent_bits(&BTRFS_I(inode)->io_tree,
 788                                  start_pos, last_pos - 1, 0, &cached_state,
 789                                  GFP_NOFS);
 790                 ordered = btrfs_lookup_first_ordered_extent(inode,
 791                                                             last_pos - 1);
 792                 if (ordered &&
 793                     ordered->file_offset + ordered->len > start_pos &&
 794                     ordered->file_offset < last_pos) {
 795                         btrfs_put_ordered_extent(ordered);
 796                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
 797                                              start_pos, last_pos - 1,
 798                                              &cached_state, GFP_NOFS);
 799                         for (i = 0; i < num_pages; i++) {
 800                                 unlock_page(pages[i]);
 801                                 page_cache_release(pages[i]);
 802                         }
 803                         btrfs_wait_ordered_range(inode, start_pos,
 804                                                  last_pos - start_pos);
 805                         goto again;
 806                 }
 807                 if (ordered)
 808                         btrfs_put_ordered_extent(ordered);
 809
 810                 clear_extent_bit(&BTRFS_I(inode)->io_tree, start_pos,
 811                                   last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC |
 812                                   EXTENT_DO_ACCOUNTING, 0, 0, &cached_state,
 813                                   GFP_NOFS);
 814                 unlock_extent_cached(&BTRFS_I(inode)->io_tree,
 815                                      start_pos, last_pos - 1, &cached_state,
 816                                      GFP_NOFS);
 817         }
 818         for (i = 0; i < num_pages; i++) {
 819                 clear_page_dirty_for_io(pages[i]);
 820                 set_page_extent_mapped(pages[i]);
 821                 WARN_ON(!PageLocked(pages[i]));
 822         }
 823         return 0;
 824 }
 825
 826 static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
 827                                 size_t count, loff_t *ppos)
 828 {
 829         loff_t pos;
 830         loff_t start_pos;
 831         ssize_t num_written = 0;
 832         ssize_t err = 0;
 833         int ret = 0;
 834         struct inode *inode = fdentry(file)->d_inode;
 835         struct btrfs_root *root = BTRFS_I(inode)->root;
 836         struct page **pages = NULL;
 837         int nrptrs;
 838         struct page *pinned[2];
 839         unsigned long first_index;
 840         unsigned long last_index;
 841         int will_write;
 842
 843         will_write = ((file->f_flags & O_DSYNC) || IS_SYNC(inode) ||
 844                       (file->f_flags & O_DIRECT));
 845
 846         nrptrs = min((count + PAGE_CACHE_SIZE - 1) / PAGE_CACHE_SIZE,
 847                      PAGE_CACHE_SIZE / (sizeof(struct page *)));
 848         pinned[0] = NULL;
 849         pinned[1] = NULL;
 850
 851         pos = *ppos;
 852         start_pos = pos;
 853
 854         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
 855
 856         /* do the reserve before the mutex lock in case we have to do some
 857          * flushing.  We wouldn't deadlock, but this is more polite.
 858          */
 859         err = btrfs_reserve_metadata_for_delalloc(root, inode, 1);
 860         if (err)
 861                 goto out_nolock;
 862
 863         mutex_lock(&inode->i_mutex);
 864
 865         current->backing_dev_info = inode->i_mapping->backing_dev_info;
 866         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
 867         if (err)
 868                 goto out;
 869
 870         if (count == 0)
 871                 goto out;
 872
 873         err = file_remove_suid(file);
 874         if (err)
 875                 goto out;
 876
 877         file_update_time(file);
 878
 879         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
 880
 881         /* generic_write_checks can change our pos */
 882         start_pos = pos;
 883
 884         BTRFS_I(inode)->sequence++;
 885         first_index = pos >> PAGE_CACHE_SHIFT;
 886         last_index = (pos + count) >> PAGE_CACHE_SHIFT;
 887
 888         /*
 889          * there are lots of better ways to do this, but this code
 890          * makes sure the first and last page in the file range are
 891          * up to date and ready for cow
 892          */
 893         if ((pos & (PAGE_CACHE_SIZE - 1))) {
 894                 pinned[0] = grab_cache_page(inode->i_mapping, first_index);
 895                 if (!PageUptodate(pinned[0])) {
 896                         ret = btrfs_readpage(NULL, pinned[0]);
 897                         BUG_ON(ret);
 898                         wait_on_page_locked(pinned[0]);
 899                 } else {
 900                         unlock_page(pinned[0]);
 901                 }
 902         }
 903         if ((pos + count) & (PAGE_CACHE_SIZE - 1)) {
 904                 pinned[1] = grab_cache_page(inode->i_mapping, last_index);
 905                 if (!PageUptodate(pinned[1])) {
 906                         ret = btrfs_readpage(NULL, pinned[1]);
 907                         BUG_ON(ret);
 908                         wait_on_page_locked(pinned[1]);
 909                 } else {
 910                         unlock_page(pinned[1]);
 911                 }
 912         }
 913
 914         while (count > 0) {
 915                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
 916                 size_t write_bytes = min(count, nrptrs *
 917                                         (size_t)PAGE_CACHE_SIZE -
 918                                          offset);
 919                 size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
 920                                         PAGE_CACHE_SHIFT;
 921
 922                 WARN_ON(num_pages > nrptrs);
 923                 memset(pages, 0, sizeof(struct page *) * nrptrs);
 924
 925                 ret = btrfs_check_data_free_space(root, inode, write_bytes);
 926                 if (ret)
 927                         goto out;
 928
 929                 ret = prepare_pages(root, file, pages, num_pages,
 930                                     pos, first_index, last_index,
 931                                     write_bytes);
 932                 if (ret) {
 933                         btrfs_free_reserved_data_space(root, inode,
 934                                                        write_bytes);
 935                         goto out;
 936                 }
 937
 938                 ret = btrfs_copy_from_user(pos, num_pages,
 939                                            write_bytes, pages, buf);
 940                 if (ret) {
 941                         btrfs_free_reserved_data_space(root, inode,
 942                                                        write_bytes);
 943                         btrfs_drop_pages(pages, num_pages);
 944                         goto out;
 945                 }
 946
 947                 ret = dirty_and_release_pages(NULL, root, file, pages,
 948                                               num_pages, pos, write_bytes);
 949                 btrfs_drop_pages(pages, num_pages);
 950                 if (ret) {
 951                         btrfs_free_reserved_data_space(root, inode,
 952                                                        write_bytes);
 953                         goto out;
 954                 }
 955
 956                 if (will_write) {
 957                         filemap_fdatawrite_range(inode->i_mapping, pos,
 958                                                  pos + write_bytes - 1);
 959                 } else {
 960                         balance_dirty_pages_ratelimited_nr(inode->i_mapping,
 961                                                            num_pages);
 962                         if (num_pages <
 963                             (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
 964                                 btrfs_btree_balance_dirty(root, 1);
 965                         btrfs_throttle(root);
 966                 }
 967
 968                 buf += write_bytes;
 969                 count -= write_bytes;
 970                 pos += write_bytes;
 971                 num_written += write_bytes;
 972
 973                 cond_resched();
 974         }
 975 out:
 976         mutex_unlock(&inode->i_mutex);
 977         if (ret)
 978                 err = ret;
 979         btrfs_unreserve_metadata_for_delalloc(root, inode, 1);
 980
 981 out_nolock:
 982         kfree(pages);
 983         if (pinned[0])
 984                 page_cache_release(pinned[0]);
 985         if (pinned[1])
 986                 page_cache_release(pinned[1]);
 987         *ppos = pos;
 988
 989         /*
 990          * we want to make sure fsync finds this change
 991          * but we haven't joined a transaction running right now.
 992          *
 993          * Later on, someone is sure to update the inode and get the
 994          * real transid recorded.
 995          *
 996          * We set last_trans now to the fs_info generation + 1,
 997          * this will either be one more than the running transaction
 998          * or the generation used for the next transaction if there isn't
 999          * one running right now.
1000          */
1001         BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
1002
1003         if (num_written > 0 && will_write) {
1004                 struct btrfs_trans_handle *trans;
1005
1006                 err = btrfs_wait_ordered_range(inode, start_pos, num_written);
1007                 if (err)
1008                         num_written = err;
1009
1010                 if ((file->f_flags & O_DSYNC) || IS_SYNC(inode)) {
1011                         trans = btrfs_start_transaction(root, 1);
1012                         ret = btrfs_log_dentry_safe(trans, root,
1013                                                     file->f_dentry);
1014                         if (ret == 0) {
1015                                 ret = btrfs_sync_log(trans, root);
1016                                 if (ret == 0)
1017                                         btrfs_end_transaction(trans, root);
1018                                 else
1019                                         btrfs_commit_transaction(trans, root);
1020                         } else if (ret != BTRFS_NO_LOG_SYNC) {
1021                                 btrfs_commit_transaction(trans, root);
1022                         } else {
1023                                 btrfs_end_transaction(trans, root);
1024                         }
1025                 }
1026                 if (file->f_flags & O_DIRECT) {
1027                         invalidate_mapping_pages(inode->i_mapping,
1028                               start_pos >> PAGE_CACHE_SHIFT,
1029                              (start_pos + num_written - 1) >> PAGE_CACHE_SHIFT);
1030                 }
1031         }
1032         current->backing_dev_info = NULL;
1033         return num_written ? num_written : err;
1034 }
1035
1036 int btrfs_release_file(struct inode *inode, struct file *filp)
1037 {
1038         /*
1039          * ordered_data_close is set by settattr when we are about to truncate
1040          * a file from a non-zero size to a zero size.  This tries to
1041          * flush down new bytes that may have been written if the
1042          * application were using truncate to replace a file in place.
1043          */
1044         if (BTRFS_I(inode)->ordered_data_close) {
1045                 BTRFS_I(inode)->ordered_data_close = 0;
1046                 btrfs_add_ordered_operation(NULL, BTRFS_I(inode)->root, inode);
1047                 if (inode->i_size > BTRFS_ORDERED_OPERATIONS_FLUSH_LIMIT)
1048                         filemap_flush(inode->i_mapping);
1049         }
1050         if (filp->private_data)
1051                 btrfs_ioctl_trans_end(filp);
1052         return 0;
1053 }
1054
1055 /*
1056  * fsync call for both files and directories.  This logs the inode into
1057  * the tree log instead of forcing full commits whenever possible.
1058  *
1059  * It needs to call filemap_fdatawait so that all ordered extent updates are
1060  * in the metadata btree are up to date for copying to the log.
1061  *
1062  * It drops the inode mutex before doing the tree log commit.  This is an
1063  * important optimization for directories because holding the mutex prevents
1064  * new operations on the dir while we write to disk.
1065  */
1066 int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
1067 {
1068         struct inode *inode = dentry->d_inode;
1069         struct btrfs_root *root = BTRFS_I(inode)->root;
1070         int ret = 0;
1071         struct btrfs_trans_handle *trans;
1072
1073
1074         /* we wait first, since the writeback may change the inode */
1075         root->log_batch++;
1076         /* the VFS called filemap_fdatawrite for us */
1077         btrfs_wait_ordered_range(inode, 0, (u64)-1);
1078         root->log_batch++;
1079
1080         /*
1081          * check the transaction that last modified this inode
1082          * and see if its already been committed
1083          */
1084         if (!BTRFS_I(inode)->last_trans)
1085                 goto out;
1086
1087         /*
1088          * if the last transaction that changed this file was before
1089          * the current transaction, we can bail out now without any
1090          * syncing
1091          */
1092         mutex_lock(&root->fs_info->trans_mutex);
1093         if (BTRFS_I(inode)->last_trans <=
1094             root->fs_info->last_trans_committed) {
1095                 BTRFS_I(inode)->last_trans = 0;
1096                 mutex_unlock(&root->fs_info->trans_mutex);
1097                 goto out;
1098         }
1099         mutex_unlock(&root->fs_info->trans_mutex);
1100
1101         /*
1102          * ok we haven't committed the transaction yet, lets do a commit
1103          */
1104         if (file && file->private_data)
1105                 btrfs_ioctl_trans_end(file);
1106
1107         trans = btrfs_start_transaction(root, 1);
1108         if (!trans) {
1109                 ret = -ENOMEM;
1110                 goto out;
1111         }
1112
1113         ret = btrfs_log_dentry_safe(trans, root, dentry);
1114         if (ret < 0)
1115                 goto out;
1116
1117         /* we've logged all the items and now have a consistent
1118          * version of the file in the log.  It is possible that
1119          * someone will come in and modify the file, but that's
1120          * fine because the log is consistent on disk, and we
1121          * have references to all of the file's extents
1122          *
1123          * It is possible that someone will come in and log the
1124          * file again, but that will end up using the synchronization
1125          * inside btrfs_sync_log to keep things safe.
1126          */
1127         mutex_unlock(&dentry->d_inode->i_mutex);
1128
1129         if (ret != BTRFS_NO_LOG_SYNC) {
1130                 if (ret > 0) {
1131                         ret = btrfs_commit_transaction(trans, root);
1132                 } else {
1133                         ret = btrfs_sync_log(trans, root);
1134                         if (ret == 0)
1135                                 ret = btrfs_end_transaction(trans, root);
1136                         else
1137                                 ret = btrfs_commit_transaction(trans, root);
1138                 }
1139         } else {
1140                 ret = btrfs_end_transaction(trans, root);
1141         }
1142         mutex_lock(&dentry->d_inode->i_mutex);
1143 out:
1144         return ret > 0 ? -EIO : ret;
1145 }
1146
1147 static const struct vm_operations_struct btrfs_file_vm_ops = {
1148         .fault          = filemap_fault,
1149         .page_mkwrite   = btrfs_page_mkwrite,
1150 };
1151
1152 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
1153 {
1154         vma->vm_ops = &btrfs_file_vm_ops;
1155         file_accessed(filp);
1156         return 0;
1157 }
1158
1159 const struct file_operations btrfs_file_operations = {
1160         .llseek         = generic_file_llseek,
1161         .read           = do_sync_read,
1162         .aio_read       = generic_file_aio_read,
1163         .splice_read    = generic_file_splice_read,
1164         .write          = btrfs_file_write,
1165         .mmap           = btrfs_file_mmap,
1166         .open           = generic_file_open,
1167         .release        = btrfs_release_file,
1168         .fsync          = btrfs_sync_file,
1169         .unlocked_ioctl = btrfs_ioctl,
1170 #ifdef CONFIG_COMPAT
1171         .compat_ioctl   = btrfs_ioctl,
1172 #endif
1173 };