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/smp_lock.h>
  26 #include <linux/backing-dev.h>
  27 #include <linux/mpage.h>
  28 #include <linux/swap.h>
  29 #include <linux/writeback.h>
  30 #include <linux/statfs.h>
  31 #include <linux/compat.h>
  32 #include "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         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 117         u64 hint_byte;
 118         u64 num_bytes;
 119         u64 start_pos;
 120         u64 end_of_last_block;
 121         u64 end_pos = pos + write_bytes;
 122         loff_t isize = i_size_read(inode);
 123
 124         start_pos = pos & ~((u64)root->sectorsize - 1);
 125         num_bytes = (write_bytes + pos - start_pos +
 126                     root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
 127
 128         end_of_last_block = start_pos + num_bytes - 1;
 129
 130         lock_extent(io_tree, start_pos, end_of_last_block, GFP_NOFS);
 131         trans = btrfs_join_transaction(root, 1);
 132         if (!trans) {
 133                 err = -ENOMEM;
 134                 goto out_unlock;
 135         }
 136         btrfs_set_trans_block_group(trans, inode);
 137         hint_byte = 0;
 138
 139         set_extent_uptodate(io_tree, start_pos, end_of_last_block, GFP_NOFS);
 140
 141         /* check for reserved extents on each page, we don't want
 142          * to reset the delalloc bit on things that already have
 143          * extents reserved.
 144          */
 145         btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block);
 146         for (i = 0; i < num_pages; i++) {
 147                 struct page *p = pages[i];
 148                 SetPageUptodate(p);
 149                 ClearPageChecked(p);
 150                 set_page_dirty(p);
 151         }
 152         if (end_pos > isize) {
 153                 i_size_write(inode, end_pos);
 154                 btrfs_update_inode(trans, root, inode);
 155         }
 156         err = btrfs_end_transaction(trans, root);
 157 out_unlock:
 158         unlock_extent(io_tree, start_pos, end_of_last_block, GFP_NOFS);
 159         return err;
 160 }
 161
 162 /*
 163  * this drops all the extents in the cache that intersect the range
 164  * [start, end].  Existing extents are split as required.
 165  */
 166 int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
 167                             int skip_pinned)
 168 {
 169         struct extent_map *em;
 170         struct extent_map *split = NULL;
 171         struct extent_map *split2 = NULL;
 172         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
 173         u64 len = end - start + 1;
 174         int ret;
 175         int testend = 1;
 176         unsigned long flags;
 177         int compressed = 0;
 178
 179         WARN_ON(end < start);
 180         if (end == (u64)-1) {
 181                 len = (u64)-1;
 182                 testend = 0;
 183         }
 184         while (1) {
 185                 if (!split)
 186                         split = alloc_extent_map(GFP_NOFS);
 187                 if (!split2)
 188                         split2 = alloc_extent_map(GFP_NOFS);
 189
 190                 spin_lock(&em_tree->lock);
 191                 em = lookup_extent_mapping(em_tree, start, len);
 192                 if (!em) {
 193                         spin_unlock(&em_tree->lock);
 194                         break;
 195                 }
 196                 flags = em->flags;
 197                 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
 198                         spin_unlock(&em_tree->lock);
 199                         if (em->start <= start &&
 200                             (!testend || em->start + em->len >= start + len)) {
 201                                 free_extent_map(em);
 202                                 break;
 203                         }
 204                         if (start < em->start) {
 205                                 len = em->start - start;
 206                         } else {
 207                                 len = start + len - (em->start + em->len);
 208                                 start = em->start + em->len;
 209                         }
 210                         free_extent_map(em);
 211                         continue;
 212                 }
 213                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 214                 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
 215                 remove_extent_mapping(em_tree, em);
 216
 217                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 218                     em->start < start) {
 219                         split->start = em->start;
 220                         split->len = start - em->start;
 221                         split->orig_start = em->orig_start;
 222                         split->block_start = em->block_start;
 223
 224                         if (compressed)
 225                                 split->block_len = em->block_len;
 226                         else
 227                                 split->block_len = split->len;
 228
 229                         split->bdev = em->bdev;
 230                         split->flags = flags;
 231                         ret = add_extent_mapping(em_tree, split);
 232                         BUG_ON(ret);
 233                         free_extent_map(split);
 234                         split = split2;
 235                         split2 = NULL;
 236                 }
 237                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 238                     testend && em->start + em->len > start + len) {
 239                         u64 diff = start + len - em->start;
 240
 241                         split->start = start + len;
 242                         split->len = em->start + em->len - (start + len);
 243                         split->bdev = em->bdev;
 244                         split->flags = flags;
 245
 246                         if (compressed) {
 247                                 split->block_len = em->block_len;
 248                                 split->block_start = em->block_start;
 249                                 split->orig_start = em->orig_start;
 250                         } else {
 251                                 split->block_len = split->len;
 252                                 split->block_start = em->block_start + diff;
 253                                 split->orig_start = split->start;
 254                         }
 255
 256                         ret = add_extent_mapping(em_tree, split);
 257                         BUG_ON(ret);
 258                         free_extent_map(split);
 259                         split = NULL;
 260                 }
 261                 spin_unlock(&em_tree->lock);
 262
 263                 /* once for us */
 264                 free_extent_map(em);
 265                 /* once for the tree*/
 266                 free_extent_map(em);
 267         }
 268         if (split)
 269                 free_extent_map(split);
 270         if (split2)
 271                 free_extent_map(split2);
 272         return 0;
 273 }
 274
 275 /*
 276  * this is very complex, but the basic idea is to drop all extents
 277  * in the range start - end.  hint_block is filled in with a block number
 278  * that would be a good hint to the block allocator for this file.
 279  *
 280  * If an extent intersects the range but is not entirely inside the range
 281  * it is either truncated or split.  Anything entirely inside the range
 282  * is deleted from the tree.
 283  *
 284  * inline_limit is used to tell this code which offsets in the file to keep
 285  * if they contain inline extents.
 286  */
 287 noinline int btrfs_drop_extents(struct btrfs_trans_handle *trans,
 288                        struct btrfs_root *root, struct inode *inode,
 289                        u64 start, u64 end, u64 locked_end,
 290                        u64 inline_limit, u64 *hint_byte)
 291 {
 292         u64 extent_end = 0;
 293         u64 search_start = start;
 294         u64 ram_bytes = 0;
 295         u64 disk_bytenr = 0;
 296         u64 orig_locked_end = locked_end;
 297         u8 compression;
 298         u8 encryption;
 299         u16 other_encoding = 0;
 300         struct extent_buffer *leaf;
 301         struct btrfs_file_extent_item *extent;
 302         struct btrfs_path *path;
 303         struct btrfs_key key;
 304         struct btrfs_file_extent_item old;
 305         int keep;
 306         int slot;
 307         int bookend;
 308         int found_type = 0;
 309         int found_extent;
 310         int found_inline;
 311         int recow;
 312         int ret;
 313
 314         inline_limit = 0;
 315         btrfs_drop_extent_cache(inode, start, end - 1, 0);
 316
 317         path = btrfs_alloc_path();
 318         if (!path)
 319                 return -ENOMEM;
 320         while (1) {
 321                 recow = 0;
 322                 btrfs_release_path(root, path);
 323                 ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
 324                                                search_start, -1);
 325                 if (ret < 0)
 326                         goto out;
 327                 if (ret > 0) {
 328                         if (path->slots[0] == 0) {
 329                                 ret = 0;
 330                                 goto out;
 331                         }
 332                         path->slots[0]--;
 333                 }
 334 next_slot:
 335                 keep = 0;
 336                 bookend = 0;
 337                 found_extent = 0;
 338                 found_inline = 0;
 339                 compression = 0;
 340                 encryption = 0;
 341                 extent = NULL;
 342                 leaf = path->nodes[0];
 343                 slot = path->slots[0];
 344                 ret = 0;
 345                 btrfs_item_key_to_cpu(leaf, &key, slot);
 346                 if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY &&
 347                     key.offset >= end) {
 348                         goto out;
 349                 }
 350                 if (btrfs_key_type(&key) > BTRFS_EXTENT_DATA_KEY ||
 351                     key.objectid != inode->i_ino) {
 352                         goto out;
 353                 }
 354                 if (recow) {
 355                         search_start = max(key.offset, start);
 356                         continue;
 357                 }
 358                 if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY) {
 359                         extent = btrfs_item_ptr(leaf, slot,
 360                                                 struct btrfs_file_extent_item);
 361                         found_type = btrfs_file_extent_type(leaf, extent);
 362                         compression = btrfs_file_extent_compression(leaf,
 363                                                                     extent);
 364                         encryption = btrfs_file_extent_encryption(leaf,
 365                                                                   extent);
 366                         other_encoding = btrfs_file_extent_other_encoding(leaf,
 367                                                                   extent);
 368                         if (found_type == BTRFS_FILE_EXTENT_REG ||
 369                             found_type == BTRFS_FILE_EXTENT_PREALLOC) {
 370                                 extent_end =
 371                                      btrfs_file_extent_disk_bytenr(leaf,
 372                                                                    extent);
 373                                 if (extent_end)
 374                                         *hint_byte = extent_end;
 375
 376                                 extent_end = key.offset +
 377                                      btrfs_file_extent_num_bytes(leaf, extent);
 378                                 ram_bytes = btrfs_file_extent_ram_bytes(leaf,
 379                                                                 extent);
 380                                 found_extent = 1;
 381                         } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
 382                                 found_inline = 1;
 383                                 extent_end = key.offset +
 384                                      btrfs_file_extent_inline_len(leaf, extent);
 385                         }
 386                 } else {
 387                         extent_end = search_start;
 388                 }
 389
 390                 /* we found nothing we can drop */
 391                 if ((!found_extent && !found_inline) ||
 392                     search_start >= extent_end) {
 393                         int nextret;
 394                         u32 nritems;
 395                         nritems = btrfs_header_nritems(leaf);
 396                         if (slot >= nritems - 1) {
 397                                 nextret = btrfs_next_leaf(root, path);
 398                                 if (nextret)
 399                                         goto out;
 400                                 recow = 1;
 401                         } else {
 402                                 path->slots[0]++;
 403                         }
 404                         goto next_slot;
 405                 }
 406
 407                 if (end <= extent_end && start >= key.offset && found_inline)
 408                         *hint_byte = EXTENT_MAP_INLINE;
 409
 410                 if (found_extent) {
 411                         read_extent_buffer(leaf, &old, (unsigned long)extent,
 412                                            sizeof(old));
 413                 }
 414
 415                 if (end < extent_end && end >= key.offset) {
 416                         bookend = 1;
 417                         if (found_inline && start <= key.offset)
 418                                 keep = 1;
 419                 }
 420
 421                 if (bookend && found_extent) {
 422                         if (locked_end < extent_end) {
 423                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
 424                                                 locked_end, extent_end - 1,
 425                                                 GFP_NOFS);
 426                                 if (!ret) {
 427                                         btrfs_release_path(root, path);
 428                                         lock_extent(&BTRFS_I(inode)->io_tree,
 429                                                 locked_end, extent_end - 1,
 430                                                 GFP_NOFS);
 431                                         locked_end = extent_end;
 432                                         continue;
 433                                 }
 434                                 locked_end = extent_end;
 435                         }
 436                         disk_bytenr = le64_to_cpu(old.disk_bytenr);
 437                         if (disk_bytenr != 0) {
 438                                 ret = btrfs_inc_extent_ref(trans, root,
 439                                            disk_bytenr,
 440                                            le64_to_cpu(old.disk_num_bytes), 0,
 441                                            root->root_key.objectid,
 442                                            key.objectid, key.offset -
 443                                            le64_to_cpu(old.offset));
 444                                 BUG_ON(ret);
 445                         }
 446                 }
 447
 448                 if (found_inline) {
 449                         u64 mask = root->sectorsize - 1;
 450                         search_start = (extent_end + mask) & ~mask;
 451                 } else
 452                         search_start = extent_end;
 453
 454                 /* truncate existing extent */
 455                 if (start > key.offset) {
 456                         u64 new_num;
 457                         u64 old_num;
 458                         keep = 1;
 459                         WARN_ON(start & (root->sectorsize - 1));
 460                         if (found_extent) {
 461                                 new_num = start - key.offset;
 462                                 old_num = btrfs_file_extent_num_bytes(leaf,
 463                                                                       extent);
 464                                 *hint_byte =
 465                                         btrfs_file_extent_disk_bytenr(leaf,
 466                                                                       extent);
 467                                 if (btrfs_file_extent_disk_bytenr(leaf,
 468                                                                   extent)) {
 469                                         inode_sub_bytes(inode, old_num -
 470                                                         new_num);
 471                                 }
 472                                 btrfs_set_file_extent_num_bytes(leaf,
 473                                                         extent, new_num);
 474                                 btrfs_mark_buffer_dirty(leaf);
 475                         } else if (key.offset < inline_limit &&
 476                                    (end > extent_end) &&
 477                                    (inline_limit < extent_end)) {
 478                                 u32 new_size;
 479                                 new_size = btrfs_file_extent_calc_inline_size(
 480                                                    inline_limit - key.offset);
 481                                 inode_sub_bytes(inode, extent_end -
 482                                                 inline_limit);
 483                                 btrfs_set_file_extent_ram_bytes(leaf, extent,
 484                                                         new_size);
 485                                 if (!compression && !encryption) {
 486                                         btrfs_truncate_item(trans, root, path,
 487                                                             new_size, 1);
 488                                 }
 489                         }
 490                 }
 491                 /* delete the entire extent */
 492                 if (!keep) {
 493                         if (found_inline)
 494                                 inode_sub_bytes(inode, extent_end -
 495                                                 key.offset);
 496                         ret = btrfs_del_item(trans, root, path);
 497                         /* TODO update progress marker and return */
 498                         BUG_ON(ret);
 499                         extent = NULL;
 500                         btrfs_release_path(root, path);
 501                         /* the extent will be freed later */
 502                 }
 503                 if (bookend && found_inline && start <= key.offset) {
 504                         u32 new_size;
 505                         new_size = btrfs_file_extent_calc_inline_size(
 506                                                    extent_end - end);
 507                         inode_sub_bytes(inode, end - key.offset);
 508                         btrfs_set_file_extent_ram_bytes(leaf, extent,
 509                                                         new_size);
 510                         if (!compression && !encryption)
 511                                 ret = btrfs_truncate_item(trans, root, path,
 512                                                           new_size, 0);
 513                         BUG_ON(ret);
 514                 }
 515                 /* create bookend, splitting the extent in two */
 516                 if (bookend && found_extent) {
 517                         struct btrfs_key ins;
 518                         ins.objectid = inode->i_ino;
 519                         ins.offset = end;
 520                         btrfs_set_key_type(&ins, BTRFS_EXTENT_DATA_KEY);
 521
 522                         btrfs_release_path(root, path);
 523                         path->leave_spinning = 1;
 524                         ret = btrfs_insert_empty_item(trans, root, path, &ins,
 525                                                       sizeof(*extent));
 526                         BUG_ON(ret);
 527
 528                         leaf = path->nodes[0];
 529                         extent = btrfs_item_ptr(leaf, path->slots[0],
 530                                                 struct btrfs_file_extent_item);
 531                         write_extent_buffer(leaf, &old,
 532                                             (unsigned long)extent, sizeof(old));
 533
 534                         btrfs_set_file_extent_compression(leaf, extent,
 535                                                           compression);
 536                         btrfs_set_file_extent_encryption(leaf, extent,
 537                                                          encryption);
 538                         btrfs_set_file_extent_other_encoding(leaf, extent,
 539                                                              other_encoding);
 540                         btrfs_set_file_extent_offset(leaf, extent,
 541                                     le64_to_cpu(old.offset) + end - key.offset);
 542                         WARN_ON(le64_to_cpu(old.num_bytes) <
 543                                 (extent_end - end));
 544                         btrfs_set_file_extent_num_bytes(leaf, extent,
 545                                                         extent_end - end);
 546
 547                         /*
 548                          * set the ram bytes to the size of the full extent
 549                          * before splitting.  This is a worst case flag,
 550                          * but its the best we can do because we don't know
 551                          * how splitting affects compression
 552                          */
 553                         btrfs_set_file_extent_ram_bytes(leaf, extent,
 554                                                         ram_bytes);
 555                         btrfs_set_file_extent_type(leaf, extent, found_type);
 556
 557                         btrfs_unlock_up_safe(path, 1);
 558                         btrfs_mark_buffer_dirty(path->nodes[0]);
 559                         btrfs_set_lock_blocking(path->nodes[0]);
 560
 561                         path->leave_spinning = 0;
 562                         btrfs_release_path(root, path);
 563                         if (disk_bytenr != 0)
 564                                 inode_add_bytes(inode, extent_end - end);
 565                 }
 566
 567                 if (found_extent && !keep) {
 568                         u64 old_disk_bytenr = le64_to_cpu(old.disk_bytenr);
 569
 570                         if (old_disk_bytenr != 0) {
 571                                 inode_sub_bytes(inode,
 572                                                 le64_to_cpu(old.num_bytes));
 573                                 ret = btrfs_free_extent(trans, root,
 574                                                 old_disk_bytenr,
 575                                                 le64_to_cpu(old.disk_num_bytes),
 576                                                 0, root->root_key.objectid,
 577                                                 key.objectid, key.offset -
 578                                                 le64_to_cpu(old.offset));
 579                                 BUG_ON(ret);
 580                                 *hint_byte = old_disk_bytenr;
 581                         }
 582                 }
 583
 584                 if (search_start >= end) {
 585                         ret = 0;
 586                         goto out;
 587                 }
 588         }
 589 out:
 590         btrfs_free_path(path);
 591         if (locked_end > orig_locked_end) {
 592                 unlock_extent(&BTRFS_I(inode)->io_tree, orig_locked_end,
 593                               locked_end - 1, GFP_NOFS);
 594         }
 595         return ret;
 596 }
 597
 598 static int extent_mergeable(struct extent_buffer *leaf, int slot,
 599                             u64 objectid, u64 bytenr, u64 *start, u64 *end)
 600 {
 601         struct btrfs_file_extent_item *fi;
 602         struct btrfs_key key;
 603         u64 extent_end;
 604
 605         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
 606                 return 0;
 607
 608         btrfs_item_key_to_cpu(leaf, &key, slot);
 609         if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
 610                 return 0;
 611
 612         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
 613         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
 614             btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
 615             btrfs_file_extent_compression(leaf, fi) ||
 616             btrfs_file_extent_encryption(leaf, fi) ||
 617             btrfs_file_extent_other_encoding(leaf, fi))
 618                 return 0;
 619
 620         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 621         if ((*start && *start != key.offset) || (*end && *end != extent_end))
 622                 return 0;
 623
 624         *start = key.offset;
 625         *end = extent_end;
 626         return 1;
 627 }
 628
 629 /*
 630  * Mark extent in the range start - end as written.
 631  *
 632  * This changes extent type from 'pre-allocated' to 'regular'. If only
 633  * part of extent is marked as written, the extent will be split into
 634  * two or three.
 635  */
 636 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
 637                               struct btrfs_root *root,
 638                               struct inode *inode, u64 start, u64 end)
 639 {
 640         struct extent_buffer *leaf;
 641         struct btrfs_path *path;
 642         struct btrfs_file_extent_item *fi;
 643         struct btrfs_key key;
 644         u64 bytenr;
 645         u64 num_bytes;
 646         u64 extent_end;
 647         u64 orig_offset;
 648         u64 other_start;
 649         u64 other_end;
 650         u64 split = start;
 651         u64 locked_end = end;
 652         int extent_type;
 653         int split_end = 1;
 654         int ret;
 655
 656         btrfs_drop_extent_cache(inode, start, end - 1, 0);
 657
 658         path = btrfs_alloc_path();
 659         BUG_ON(!path);
 660 again:
 661         key.objectid = inode->i_ino;
 662         key.type = BTRFS_EXTENT_DATA_KEY;
 663         if (split == start)
 664                 key.offset = split;
 665         else
 666                 key.offset = split - 1;
 667
 668         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 669         if (ret > 0 && path->slots[0] > 0)
 670                 path->slots[0]--;
 671
 672         leaf = path->nodes[0];
 673         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 674         BUG_ON(key.objectid != inode->i_ino ||
 675                key.type != BTRFS_EXTENT_DATA_KEY);
 676         fi = btrfs_item_ptr(leaf, path->slots[0],
 677                             struct btrfs_file_extent_item);
 678         extent_type = btrfs_file_extent_type(leaf, fi);
 679         BUG_ON(extent_type != BTRFS_FILE_EXTENT_PREALLOC);
 680         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 681         BUG_ON(key.offset > start || extent_end < end);
 682
 683         bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 684         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
 685         orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
 686
 687         if (key.offset == start)
 688                 split = end;
 689
 690         if (key.offset == start && extent_end == end) {
 691                 int del_nr = 0;
 692                 int del_slot = 0;
 693                 other_start = end;
 694                 other_end = 0;
 695                 if (extent_mergeable(leaf, path->slots[0] + 1, inode->i_ino,
 696                                      bytenr, &other_start, &other_end)) {
 697                         extent_end = other_end;
 698                         del_slot = path->slots[0] + 1;
 699                         del_nr++;
 700                         ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
 701                                                 0, root->root_key.objectid,
 702                                                 inode->i_ino, orig_offset);
 703                         BUG_ON(ret);
 704                 }
 705                 other_start = 0;
 706                 other_end = start;
 707                 if (extent_mergeable(leaf, path->slots[0] - 1, inode->i_ino,
 708                                      bytenr, &other_start, &other_end)) {
 709                         key.offset = other_start;
 710                         del_slot = path->slots[0];
 711                         del_nr++;
 712                         ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
 713                                                 0, root->root_key.objectid,
 714                                                 inode->i_ino, orig_offset);
 715                         BUG_ON(ret);
 716                 }
 717                 split_end = 0;
 718                 if (del_nr == 0) {
 719                         btrfs_set_file_extent_type(leaf, fi,
 720                                                    BTRFS_FILE_EXTENT_REG);
 721                         goto done;
 722                 }
 723
 724                 fi = btrfs_item_ptr(leaf, del_slot - 1,
 725                                     struct btrfs_file_extent_item);
 726                 btrfs_set_file_extent_type(leaf, fi, BTRFS_FILE_EXTENT_REG);
 727                 btrfs_set_file_extent_num_bytes(leaf, fi,
 728                                                 extent_end - key.offset);
 729                 btrfs_mark_buffer_dirty(leaf);
 730
 731                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
 732                 BUG_ON(ret);
 733                 goto release;
 734         } else if (split == start) {
 735                 if (locked_end < extent_end) {
 736                         ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
 737                                         locked_end, extent_end - 1, GFP_NOFS);
 738                         if (!ret) {
 739                                 btrfs_release_path(root, path);
 740                                 lock_extent(&BTRFS_I(inode)->io_tree,
 741                                         locked_end, extent_end - 1, GFP_NOFS);
 742                                 locked_end = extent_end;
 743                                 goto again;
 744                         }
 745                         locked_end = extent_end;
 746                 }
 747                 btrfs_set_file_extent_num_bytes(leaf, fi, split - key.offset);
 748         } else  {
 749                 BUG_ON(key.offset != start);
 750                 key.offset = split;
 751                 btrfs_set_file_extent_offset(leaf, fi, key.offset -
 752                                              orig_offset);
 753                 btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - split);
 754                 btrfs_set_item_key_safe(trans, root, path, &key);
 755                 extent_end = split;
 756         }
 757
 758         if (extent_end == end) {
 759                 split_end = 0;
 760                 extent_type = BTRFS_FILE_EXTENT_REG;
 761         }
 762         if (extent_end == end && split == start) {
 763                 other_start = end;
 764                 other_end = 0;
 765                 if (extent_mergeable(leaf, path->slots[0] + 1, inode->i_ino,
 766                                      bytenr, &other_start, &other_end)) {
 767                         path->slots[0]++;
 768                         fi = btrfs_item_ptr(leaf, path->slots[0],
 769                                             struct btrfs_file_extent_item);
 770                         key.offset = split;
 771                         btrfs_set_item_key_safe(trans, root, path, &key);
 772                         btrfs_set_file_extent_offset(leaf, fi, key.offset -
 773                                                      orig_offset);
 774                         btrfs_set_file_extent_num_bytes(leaf, fi,
 775                                                         other_end - split);
 776                         goto done;
 777                 }
 778         }
 779         if (extent_end == end && split == end) {
 780                 other_start = 0;
 781                 other_end = start;
 782                 if (extent_mergeable(leaf, path->slots[0] - 1 , inode->i_ino,
 783                                      bytenr, &other_start, &other_end)) {
 784                         path->slots[0]--;
 785                         fi = btrfs_item_ptr(leaf, path->slots[0],
 786                                             struct btrfs_file_extent_item);
 787                         btrfs_set_file_extent_num_bytes(leaf, fi, extent_end -
 788                                                         other_start);
 789                         goto done;
 790                 }
 791         }
 792
 793         btrfs_mark_buffer_dirty(leaf);
 794
 795         ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
 796                                    root->root_key.objectid,
 797                                    inode->i_ino, orig_offset);
 798         BUG_ON(ret);
 799         btrfs_release_path(root, path);
 800
 801         key.offset = start;
 802         ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*fi));
 803         BUG_ON(ret);
 804
 805         leaf = path->nodes[0];
 806         fi = btrfs_item_ptr(leaf, path->slots[0],
 807                             struct btrfs_file_extent_item);
 808         btrfs_set_file_extent_generation(leaf, fi, trans->transid);
 809         btrfs_set_file_extent_type(leaf, fi, extent_type);
 810         btrfs_set_file_extent_disk_bytenr(leaf, fi, bytenr);
 811         btrfs_set_file_extent_disk_num_bytes(leaf, fi, num_bytes);
 812         btrfs_set_file_extent_offset(leaf, fi, key.offset - orig_offset);
 813         btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - key.offset);
 814         btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
 815         btrfs_set_file_extent_compression(leaf, fi, 0);
 816         btrfs_set_file_extent_encryption(leaf, fi, 0);
 817         btrfs_set_file_extent_other_encoding(leaf, fi, 0);
 818 done:
 819         btrfs_mark_buffer_dirty(leaf);
 820
 821 release:
 822         btrfs_release_path(root, path);
 823         if (split_end && split == start) {
 824                 split = end;
 825                 goto again;
 826         }
 827         if (locked_end > end) {
 828                 unlock_extent(&BTRFS_I(inode)->io_tree, end, locked_end - 1,
 829                               GFP_NOFS);
 830         }
 831         btrfs_free_path(path);
 832         return 0;
 833 }
 834
 835 /*
 836  * this gets pages into the page cache and locks them down, it also properly
 837  * waits for data=ordered extents to finish before allowing the pages to be
 838  * modified.
 839  */
 840 static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
 841                          struct page **pages, size_t num_pages,
 842                          loff_t pos, unsigned long first_index,
 843                          unsigned long last_index, size_t write_bytes)
 844 {
 845         int i;
 846         unsigned long index = pos >> PAGE_CACHE_SHIFT;
 847         struct inode *inode = fdentry(file)->d_inode;
 848         int err = 0;
 849         u64 start_pos;
 850         u64 last_pos;
 851
 852         start_pos = pos & ~((u64)root->sectorsize - 1);
 853         last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
 854
 855         if (start_pos > inode->i_size) {
 856                 err = btrfs_cont_expand(inode, start_pos);
 857                 if (err)
 858                         return err;
 859         }
 860
 861         memset(pages, 0, num_pages * sizeof(struct page *));
 862 again:
 863         for (i = 0; i < num_pages; i++) {
 864                 pages[i] = grab_cache_page(inode->i_mapping, index + i);
 865                 if (!pages[i]) {
 866                         err = -ENOMEM;
 867                         BUG_ON(1);
 868                 }
 869                 wait_on_page_writeback(pages[i]);
 870         }
 871         if (start_pos < inode->i_size) {
 872                 struct btrfs_ordered_extent *ordered;
 873                 lock_extent(&BTRFS_I(inode)->io_tree,
 874                             start_pos, last_pos - 1, GFP_NOFS);
 875                 ordered = btrfs_lookup_first_ordered_extent(inode,
 876                                                             last_pos - 1);
 877                 if (ordered &&
 878                     ordered->file_offset + ordered->len > start_pos &&
 879                     ordered->file_offset < last_pos) {
 880                         btrfs_put_ordered_extent(ordered);
 881                         unlock_extent(&BTRFS_I(inode)->io_tree,
 882                                       start_pos, last_pos - 1, GFP_NOFS);
 883                         for (i = 0; i < num_pages; i++) {
 884                                 unlock_page(pages[i]);
 885                                 page_cache_release(pages[i]);
 886                         }
 887                         btrfs_wait_ordered_range(inode, start_pos,
 888                                                  last_pos - start_pos);
 889                         goto again;
 890                 }
 891                 if (ordered)
 892                         btrfs_put_ordered_extent(ordered);
 893
 894                 clear_extent_bits(&BTRFS_I(inode)->io_tree, start_pos,
 895                                   last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC,
 896                                   GFP_NOFS);
 897                 unlock_extent(&BTRFS_I(inode)->io_tree,
 898                               start_pos, last_pos - 1, GFP_NOFS);
 899         }
 900         for (i = 0; i < num_pages; i++) {
 901                 clear_page_dirty_for_io(pages[i]);
 902                 set_page_extent_mapped(pages[i]);
 903                 WARN_ON(!PageLocked(pages[i]));
 904         }
 905         return 0;
 906 }
 907
 908 static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
 909                                 size_t count, loff_t *ppos)
 910 {
 911         loff_t pos;
 912         loff_t start_pos;
 913         ssize_t num_written = 0;
 914         ssize_t err = 0;
 915         int ret = 0;
 916         struct inode *inode = fdentry(file)->d_inode;
 917         struct btrfs_root *root = BTRFS_I(inode)->root;
 918         struct page **pages = NULL;
 919         int nrptrs;
 920         struct page *pinned[2];
 921         unsigned long first_index;
 922         unsigned long last_index;
 923         int will_write;
 924
 925         will_write = ((file->f_flags & O_SYNC) || IS_SYNC(inode) ||
 926                       (file->f_flags & O_DIRECT));
 927
 928         nrptrs = min((count + PAGE_CACHE_SIZE - 1) / PAGE_CACHE_SIZE,
 929                      PAGE_CACHE_SIZE / (sizeof(struct page *)));
 930         pinned[0] = NULL;
 931         pinned[1] = NULL;
 932
 933         pos = *ppos;
 934         start_pos = pos;
 935
 936         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
 937         current->backing_dev_info = inode->i_mapping->backing_dev_info;
 938         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
 939         if (err)
 940                 goto out_nolock;
 941         if (count == 0)
 942                 goto out_nolock;
 943
 944         err = file_remove_suid(file);
 945         if (err)
 946                 goto out_nolock;
 947         file_update_time(file);
 948
 949         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
 950
 951         mutex_lock(&inode->i_mutex);
 952         BTRFS_I(inode)->sequence++;
 953         first_index = pos >> PAGE_CACHE_SHIFT;
 954         last_index = (pos + count) >> PAGE_CACHE_SHIFT;
 955
 956         /*
 957          * there are lots of better ways to do this, but this code
 958          * makes sure the first and last page in the file range are
 959          * up to date and ready for cow
 960          */
 961         if ((pos & (PAGE_CACHE_SIZE - 1))) {
 962                 pinned[0] = grab_cache_page(inode->i_mapping, first_index);
 963                 if (!PageUptodate(pinned[0])) {
 964                         ret = btrfs_readpage(NULL, pinned[0]);
 965                         BUG_ON(ret);
 966                         wait_on_page_locked(pinned[0]);
 967                 } else {
 968                         unlock_page(pinned[0]);
 969                 }
 970         }
 971         if ((pos + count) & (PAGE_CACHE_SIZE - 1)) {
 972                 pinned[1] = grab_cache_page(inode->i_mapping, last_index);
 973                 if (!PageUptodate(pinned[1])) {
 974                         ret = btrfs_readpage(NULL, pinned[1]);
 975                         BUG_ON(ret);
 976                         wait_on_page_locked(pinned[1]);
 977                 } else {
 978                         unlock_page(pinned[1]);
 979                 }
 980         }
 981
 982         while (count > 0) {
 983                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
 984                 size_t write_bytes = min(count, nrptrs *
 985                                         (size_t)PAGE_CACHE_SIZE -
 986                                          offset);
 987                 size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
 988                                         PAGE_CACHE_SHIFT;
 989
 990                 WARN_ON(num_pages > nrptrs);
 991                 memset(pages, 0, sizeof(struct page *) * nrptrs);
 992
 993                 ret = btrfs_check_data_free_space(root, inode, write_bytes);
 994                 if (ret)
 995                         goto out;
 996
 997                 ret = prepare_pages(root, file, pages, num_pages,
 998                                     pos, first_index, last_index,
 999                                     write_bytes);
1000                 if (ret) {
1001                         btrfs_free_reserved_data_space(root, inode,
1002                                                        write_bytes);
1003                         goto out;
1004                 }
1005
1006                 ret = btrfs_copy_from_user(pos, num_pages,
1007                                            write_bytes, pages, buf);
1008                 if (ret) {
1009                         btrfs_free_reserved_data_space(root, inode,
1010                                                        write_bytes);
1011                         btrfs_drop_pages(pages, num_pages);
1012                         goto out;
1013                 }
1014
1015                 ret = dirty_and_release_pages(NULL, root, file, pages,
1016                                               num_pages, pos, write_bytes);
1017                 btrfs_drop_pages(pages, num_pages);
1018                 if (ret) {
1019                         btrfs_free_reserved_data_space(root, inode,
1020                                                        write_bytes);
1021                         goto out;
1022                 }
1023
1024                 if (will_write) {
1025                         btrfs_fdatawrite_range(inode->i_mapping, pos,
1026                                                pos + write_bytes - 1,
1027                                                WB_SYNC_ALL);
1028                 } else {
1029                         balance_dirty_pages_ratelimited_nr(inode->i_mapping,
1030                                                            num_pages);
1031                         if (num_pages <
1032                             (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
1033                                 btrfs_btree_balance_dirty(root, 1);
1034                         btrfs_throttle(root);
1035                 }
1036
1037                 buf += write_bytes;
1038                 count -= write_bytes;
1039                 pos += write_bytes;
1040                 num_written += write_bytes;
1041
1042                 cond_resched();
1043         }
1044 out:
1045         mutex_unlock(&inode->i_mutex);
1046         if (ret)
1047                 err = ret;
1048
1049 out_nolock:
1050         kfree(pages);
1051         if (pinned[0])
1052                 page_cache_release(pinned[0]);
1053         if (pinned[1])
1054                 page_cache_release(pinned[1]);
1055         *ppos = pos;
1056
1057         /*
1058          * we want to make sure fsync finds this change
1059          * but we haven't joined a transaction running right now.
1060          *
1061          * Later on, someone is sure to update the inode and get the
1062          * real transid recorded.
1063          *
1064          * We set last_trans now to the fs_info generation + 1,
1065          * this will either be one more than the running transaction
1066          * or the generation used for the next transaction if there isn't
1067          * one running right now.
1068          */
1069         BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
1070
1071         if (num_written > 0 && will_write) {
1072                 struct btrfs_trans_handle *trans;
1073
1074                 err = btrfs_wait_ordered_range(inode, start_pos, num_written);
1075                 if (err)
1076                         num_written = err;
1077
1078                 if ((file->f_flags & O_SYNC) || IS_SYNC(inode)) {
1079                         trans = btrfs_start_transaction(root, 1);
1080                         ret = btrfs_log_dentry_safe(trans, root,
1081                                                     file->f_dentry);
1082                         if (ret == 0) {
1083                                 ret = btrfs_sync_log(trans, root);
1084                                 if (ret == 0)
1085                                         btrfs_end_transaction(trans, root);
1086                                 else
1087                                         btrfs_commit_transaction(trans, root);
1088                         } else {
1089                                 btrfs_commit_transaction(trans, root);
1090                         }
1091                 }
1092                 if (file->f_flags & O_DIRECT) {
1093                         invalidate_mapping_pages(inode->i_mapping,
1094                               start_pos >> PAGE_CACHE_SHIFT,
1095                              (start_pos + num_written - 1) >> PAGE_CACHE_SHIFT);
1096                 }
1097         }
1098         current->backing_dev_info = NULL;
1099         return num_written ? num_written : err;
1100 }
1101
1102 int btrfs_release_file(struct inode *inode, struct file *filp)
1103 {
1104         /*
1105          * ordered_data_close is set by settattr when we are about to truncate
1106          * a file from a non-zero size to a zero size.  This tries to
1107          * flush down new bytes that may have been written if the
1108          * application were using truncate to replace a file in place.
1109          */
1110         if (BTRFS_I(inode)->ordered_data_close) {
1111                 BTRFS_I(inode)->ordered_data_close = 0;
1112                 btrfs_add_ordered_operation(NULL, BTRFS_I(inode)->root, inode);
1113                 if (inode->i_size > BTRFS_ORDERED_OPERATIONS_FLUSH_LIMIT)
1114                         filemap_flush(inode->i_mapping);
1115         }
1116         if (filp->private_data)
1117                 btrfs_ioctl_trans_end(filp);
1118         return 0;
1119 }
1120
1121 /*
1122  * fsync call for both files and directories.  This logs the inode into
1123  * the tree log instead of forcing full commits whenever possible.
1124  *
1125  * It needs to call filemap_fdatawait so that all ordered extent updates are
1126  * in the metadata btree are up to date for copying to the log.
1127  *
1128  * It drops the inode mutex before doing the tree log commit.  This is an
1129  * important optimization for directories because holding the mutex prevents
1130  * new operations on the dir while we write to disk.
1131  */
1132 int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
1133 {
1134         struct inode *inode = dentry->d_inode;
1135         struct btrfs_root *root = BTRFS_I(inode)->root;
1136         int ret = 0;
1137         struct btrfs_trans_handle *trans;
1138
1139         /*
1140          * check the transaction that last modified this inode
1141          * and see if its already been committed
1142          */
1143         if (!BTRFS_I(inode)->last_trans)
1144                 goto out;
1145
1146         mutex_lock(&root->fs_info->trans_mutex);
1147         if (BTRFS_I(inode)->last_trans <=
1148             root->fs_info->last_trans_committed) {
1149                 BTRFS_I(inode)->last_trans = 0;
1150                 mutex_unlock(&root->fs_info->trans_mutex);
1151                 goto out;
1152         }
1153         mutex_unlock(&root->fs_info->trans_mutex);
1154
1155         root->log_batch++;
1156         filemap_fdatawrite(inode->i_mapping);
1157         btrfs_wait_ordered_range(inode, 0, (u64)-1);
1158         root->log_batch++;
1159
1160         /*
1161          * ok we haven't committed the transaction yet, lets do a commit
1162          */
1163         if (file && file->private_data)
1164                 btrfs_ioctl_trans_end(file);
1165
1166         trans = btrfs_start_transaction(root, 1);
1167         if (!trans) {
1168                 ret = -ENOMEM;
1169                 goto out;
1170         }
1171
1172         ret = btrfs_log_dentry_safe(trans, root, dentry);
1173         if (ret < 0)
1174                 goto out;
1175
1176         /* we've logged all the items and now have a consistent
1177          * version of the file in the log.  It is possible that
1178          * someone will come in and modify the file, but that's
1179          * fine because the log is consistent on disk, and we
1180          * have references to all of the file's extents
1181          *
1182          * It is possible that someone will come in and log the
1183          * file again, but that will end up using the synchronization
1184          * inside btrfs_sync_log to keep things safe.
1185          */
1186         mutex_unlock(&dentry->d_inode->i_mutex);
1187
1188         if (ret > 0) {
1189                 ret = btrfs_commit_transaction(trans, root);
1190         } else {
1191                 ret = btrfs_sync_log(trans, root);
1192                 if (ret == 0)
1193                         ret = btrfs_end_transaction(trans, root);
1194                 else
1195                         ret = btrfs_commit_transaction(trans, root);
1196         }
1197         mutex_lock(&dentry->d_inode->i_mutex);
1198 out:
1199         return ret > 0 ? EIO : ret;
1200 }
1201
1202 static struct vm_operations_struct btrfs_file_vm_ops = {
1203         .fault          = filemap_fault,
1204         .page_mkwrite   = btrfs_page_mkwrite,
1205 };
1206
1207 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
1208 {
1209         vma->vm_ops = &btrfs_file_vm_ops;
1210         file_accessed(filp);
1211         return 0;
1212 }
1213
1214 struct file_operations btrfs_file_operations = {
1215         .llseek         = generic_file_llseek,
1216         .read           = do_sync_read,
1217         .aio_read       = generic_file_aio_read,
1218         .splice_read    = generic_file_splice_read,
1219         .write          = btrfs_file_write,
1220         .mmap           = btrfs_file_mmap,
1221         .open           = generic_file_open,
1222         .release        = btrfs_release_file,
1223         .fsync          = btrfs_sync_file,
1224         .unlocked_ioctl = btrfs_ioctl,
1225 #ifdef CONFIG_COMPAT
1226         .compat_ioctl   = btrfs_ioctl,
1227 #endif
1228 };