SAFE public projects git trees. - safe/jmp/linux-2.6/blob - fs/btrfs/file.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/fs.h>
  20 #include <linux/pagemap.h>
  21 #include <linux/highmem.h>
  22 #include <linux/time.h>
  23 #include <linux/init.h>
  24 #include <linux/string.h>
  25 #include <linux/backing-dev.h>
  26 #include <linux/mpage.h>
  27 #include <linux/swap.h>
  28 #include <linux/writeback.h>
  29 #include <linux/statfs.h>
  30 #include <linux/compat.h>
  31 #include "ctree.h"
  32 #include "disk-io.h"
  33 #include "transaction.h"
  34 #include "btrfs_inode.h"
  35 #include "ioctl.h"
  36 #include "print-tree.h"
  37 #include "tree-log.h"
  38 #include "locking.h"
  39 #include "compat.h"
  40
  41
  42 /* simple helper to fault in pages and copy.  This should go away
  43  * and be replaced with calls into generic code.
  44  */
  45 static noinline int btrfs_copy_from_user(loff_t pos, int num_pages,
  46                                          int write_bytes,
  47                                          struct page **prepared_pages,
  48                                          const char __user *buf)
  49 {
  50         long page_fault = 0;
  51         int i;
  52         int offset = pos & (PAGE_CACHE_SIZE - 1);
  53
  54         for (i = 0; i < num_pages && write_bytes > 0; i++, offset = 0) {
  55                 size_t count = min_t(size_t,
  56                                      PAGE_CACHE_SIZE - offset, write_bytes);
  57                 struct page *page = prepared_pages[i];
  58                 fault_in_pages_readable(buf, count);
  59
  60                 /* Copy data from userspace to the current page */
  61                 kmap(page);
  62                 page_fault = __copy_from_user(page_address(page) + offset,
  63                                               buf, count);
  64                 /* Flush processor's dcache for this page */
  65                 flush_dcache_page(page);
  66                 kunmap(page);
  67                 buf += count;
  68                 write_bytes -= count;
  69
  70                 if (page_fault)
  71                         break;
  72         }
  73         return page_fault ? -EFAULT : 0;
  74 }
  75
  76 /*
  77  * unlocks pages after btrfs_file_write is done with them
  78  */
  79 static noinline void btrfs_drop_pages(struct page **pages, size_t num_pages)
  80 {
  81         size_t i;
  82         for (i = 0; i < num_pages; i++) {
  83                 if (!pages[i])
  84                         break;
  85                 /* page checked is some magic around finding pages that
  86                  * have been modified without going through btrfs_set_page_dirty
  87                  * clear it here
  88                  */
  89                 ClearPageChecked(pages[i]);
  90                 unlock_page(pages[i]);
  91                 mark_page_accessed(pages[i]);
  92                 page_cache_release(pages[i]);
  93         }
  94 }
  95
  96 /*
  97  * after copy_from_user, pages need to be dirtied and we need to make
  98  * sure holes are created between the current EOF and the start of
  99  * any next extents (if required).
 100  *
 101  * this also makes the decision about creating an inline extent vs
 102  * doing real data extents, marking pages dirty and delalloc as required.
 103  */
 104 static noinline int dirty_and_release_pages(struct btrfs_trans_handle *trans,
 105                                    struct btrfs_root *root,
 106                                    struct file *file,
 107                                    struct page **pages,
 108                                    size_t num_pages,
 109                                    loff_t pos,
 110                                    size_t write_bytes)
 111 {
 112         int err = 0;
 113         int i;
 114         struct inode *inode = fdentry(file)->d_inode;
 115         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 116         u64 hint_byte;
 117         u64 num_bytes;
 118         u64 start_pos;
 119         u64 end_of_last_block;
 120         u64 end_pos = pos + write_bytes;
 121         loff_t isize = i_size_read(inode);
 122
 123         start_pos = pos & ~((u64)root->sectorsize - 1);
 124         num_bytes = (write_bytes + pos - start_pos +
 125                     root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
 126
 127         end_of_last_block = start_pos + num_bytes - 1;
 128
 129         lock_extent(io_tree, start_pos, end_of_last_block, GFP_NOFS);
 130         trans = btrfs_join_transaction(root, 1);
 131         if (!trans) {
 132                 err = -ENOMEM;
 133                 goto out_unlock;
 134         }
 135         btrfs_set_trans_block_group(trans, inode);
 136         hint_byte = 0;
 137
 138         set_extent_uptodate(io_tree, start_pos, end_of_last_block, GFP_NOFS);
 139
 140         /* check for reserved extents on each page, we don't want
 141          * to reset the delalloc bit on things that already have
 142          * extents reserved.
 143          */
 144         btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block);
 145         for (i = 0; i < num_pages; i++) {
 146                 struct page *p = pages[i];
 147                 SetPageUptodate(p);
 148                 ClearPageChecked(p);
 149                 set_page_dirty(p);
 150         }
 151         if (end_pos > isize) {
 152                 i_size_write(inode, end_pos);
 153                 /* we've only changed i_size in ram, and we haven't updated
 154                  * the disk i_size.  There is no need to log the inode
 155                  * at this time.
 156                  */
 157         }
 158         err = btrfs_end_transaction(trans, root);
 159 out_unlock:
 160         unlock_extent(io_tree, start_pos, end_of_last_block, GFP_NOFS);
 161         return err;
 162 }
 163
 164 /*
 165  * this drops all the extents in the cache that intersect the range
 166  * [start, end].  Existing extents are split as required.
 167  */
 168 int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
 169                             int skip_pinned)
 170 {
 171         struct extent_map *em;
 172         struct extent_map *split = NULL;
 173         struct extent_map *split2 = NULL;
 174         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
 175         u64 len = end - start + 1;
 176         int ret;
 177         int testend = 1;
 178         unsigned long flags;
 179         int compressed = 0;
 180
 181         WARN_ON(end < start);
 182         if (end == (u64)-1) {
 183                 len = (u64)-1;
 184                 testend = 0;
 185         }
 186         while (1) {
 187                 if (!split)
 188                         split = alloc_extent_map(GFP_NOFS);
 189                 if (!split2)
 190                         split2 = alloc_extent_map(GFP_NOFS);
 191
 192                 spin_lock(&em_tree->lock);
 193                 em = lookup_extent_mapping(em_tree, start, len);
 194                 if (!em) {
 195                         spin_unlock(&em_tree->lock);
 196                         break;
 197                 }
 198                 flags = em->flags;
 199                 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
 200                         spin_unlock(&em_tree->lock);
 201                         if (em->start <= start &&
 202                             (!testend || em->start + em->len >= start + len)) {
 203                                 free_extent_map(em);
 204                                 break;
 205                         }
 206                         if (start < em->start) {
 207                                 len = em->start - start;
 208                         } else {
 209                                 len = start + len - (em->start + em->len);
 210                                 start = em->start + em->len;
 211                         }
 212                         free_extent_map(em);
 213                         continue;
 214                 }
 215                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 216                 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
 217                 remove_extent_mapping(em_tree, em);
 218
 219                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 220                     em->start < start) {
 221                         split->start = em->start;
 222                         split->len = start - em->start;
 223                         split->orig_start = em->orig_start;
 224                         split->block_start = em->block_start;
 225
 226                         if (compressed)
 227                                 split->block_len = em->block_len;
 228                         else
 229                                 split->block_len = split->len;
 230
 231                         split->bdev = em->bdev;
 232                         split->flags = flags;
 233                         ret = add_extent_mapping(em_tree, split);
 234                         BUG_ON(ret);
 235                         free_extent_map(split);
 236                         split = split2;
 237                         split2 = NULL;
 238                 }
 239                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 240                     testend && em->start + em->len > start + len) {
 241                         u64 diff = start + len - em->start;
 242
 243                         split->start = start + len;
 244                         split->len = em->start + em->len - (start + len);
 245                         split->bdev = em->bdev;
 246                         split->flags = flags;
 247
 248                         if (compressed) {
 249                                 split->block_len = em->block_len;
 250                                 split->block_start = em->block_start;
 251                                 split->orig_start = em->orig_start;
 252                         } else {
 253                                 split->block_len = split->len;
 254                                 split->block_start = em->block_start + diff;
 255                                 split->orig_start = split->start;
 256                         }
 257
 258                         ret = add_extent_mapping(em_tree, split);
 259                         BUG_ON(ret);
 260                         free_extent_map(split);
 261                         split = NULL;
 262                 }
 263                 spin_unlock(&em_tree->lock);
 264
 265                 /* once for us */
 266                 free_extent_map(em);
 267                 /* once for the tree*/
 268                 free_extent_map(em);
 269         }
 270         if (split)
 271                 free_extent_map(split);
 272         if (split2)
 273                 free_extent_map(split2);
 274         return 0;
 275 }
 276
 277 /*
 278  * this is very complex, but the basic idea is to drop all extents
 279  * in the range start - end.  hint_block is filled in with a block number
 280  * that would be a good hint to the block allocator for this file.
 281  *
 282  * If an extent intersects the range but is not entirely inside the range
 283  * it is either truncated or split.  Anything entirely inside the range
 284  * is deleted from the tree.
 285  *
 286  * inline_limit is used to tell this code which offsets in the file to keep
 287  * if they contain inline extents.
 288  */
 289 noinline int btrfs_drop_extents(struct btrfs_trans_handle *trans,
 290                        struct btrfs_root *root, struct inode *inode,
 291                        u64 start, u64 end, u64 locked_end,
 292                        u64 inline_limit, u64 *hint_byte)
 293 {
 294         u64 extent_end = 0;
 295         u64 search_start = start;
 296         u64 ram_bytes = 0;
 297         u64 disk_bytenr = 0;
 298         u64 orig_locked_end = locked_end;
 299         u8 compression;
 300         u8 encryption;
 301         u16 other_encoding = 0;
 302         struct extent_buffer *leaf;
 303         struct btrfs_file_extent_item *extent;
 304         struct btrfs_path *path;
 305         struct btrfs_key key;
 306         struct btrfs_file_extent_item old;
 307         int keep;
 308         int slot;
 309         int bookend;
 310         int found_type = 0;
 311         int found_extent;
 312         int found_inline;
 313         int recow;
 314         int ret;
 315
 316         inline_limit = 0;
 317         btrfs_drop_extent_cache(inode, start, end - 1, 0);
 318
 319         path = btrfs_alloc_path();
 320         if (!path)
 321                 return -ENOMEM;
 322         while (1) {
 323                 recow = 0;
 324                 btrfs_release_path(root, path);
 325                 ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
 326                                                search_start, -1);
 327                 if (ret < 0)
 328                         goto out;
 329                 if (ret > 0) {
 330                         if (path->slots[0] == 0) {
 331                                 ret = 0;
 332                                 goto out;
 333                         }
 334                         path->slots[0]--;
 335                 }
 336 next_slot:
 337                 keep = 0;
 338                 bookend = 0;
 339                 found_extent = 0;
 340                 found_inline = 0;
 341                 compression = 0;
 342                 encryption = 0;
 343                 extent = NULL;
 344                 leaf = path->nodes[0];
 345                 slot = path->slots[0];
 346                 ret = 0;
 347                 btrfs_item_key_to_cpu(leaf, &key, slot);
 348                 if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY &&
 349                     key.offset >= end) {
 350                         goto out;
 351                 }
 352                 if (btrfs_key_type(&key) > BTRFS_EXTENT_DATA_KEY ||
 353                     key.objectid != inode->i_ino) {
 354                         goto out;
 355                 }
 356                 if (recow) {
 357                         search_start = max(key.offset, start);
 358                         continue;
 359                 }
 360                 if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY) {
 361                         extent = btrfs_item_ptr(leaf, slot,
 362                                                 struct btrfs_file_extent_item);
 363                         found_type = btrfs_file_extent_type(leaf, extent);
 364                         compression = btrfs_file_extent_compression(leaf,
 365                                                                     extent);
 366                         encryption = btrfs_file_extent_encryption(leaf,
 367                                                                   extent);
 368                         other_encoding = btrfs_file_extent_other_encoding(leaf,
 369                                                                   extent);
 370                         if (found_type == BTRFS_FILE_EXTENT_REG ||
 371                             found_type == BTRFS_FILE_EXTENT_PREALLOC) {
 372                                 extent_end =
 373                                      btrfs_file_extent_disk_bytenr(leaf,
 374                                                                    extent);
 375                                 if (extent_end)
 376                                         *hint_byte = extent_end;
 377
 378                                 extent_end = key.offset +
 379                                      btrfs_file_extent_num_bytes(leaf, extent);
 380                                 ram_bytes = btrfs_file_extent_ram_bytes(leaf,
 381                                                                 extent);
 382                                 found_extent = 1;
 383                         } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
 384                                 found_inline = 1;
 385                                 extent_end = key.offset +
 386                                      btrfs_file_extent_inline_len(leaf, extent);
 387                         }
 388                 } else {
 389                         extent_end = search_start;
 390                 }
 391
 392                 /* we found nothing we can drop */
 393                 if ((!found_extent && !found_inline) ||
 394                     search_start >= extent_end) {
 395                         int nextret;
 396                         u32 nritems;
 397                         nritems = btrfs_header_nritems(leaf);
 398                         if (slot >= nritems - 1) {
 399                                 nextret = btrfs_next_leaf(root, path);
 400                                 if (nextret)
 401                                         goto out;
 402                                 recow = 1;
 403                         } else {
 404                                 path->slots[0]++;
 405                         }
 406                         goto next_slot;
 407                 }
 408
 409                 if (end <= extent_end && start >= key.offset && found_inline)
 410                         *hint_byte = EXTENT_MAP_INLINE;
 411
 412                 if (found_extent) {
 413                         read_extent_buffer(leaf, &old, (unsigned long)extent,
 414                                            sizeof(old));
 415                 }
 416
 417                 if (end < extent_end && end >= key.offset) {
 418                         bookend = 1;
 419                         if (found_inline && start <= key.offset)
 420                                 keep = 1;
 421                 }
 422
 423                 if (bookend && found_extent) {
 424                         if (locked_end < extent_end) {
 425                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
 426                                                 locked_end, extent_end - 1,
 427                                                 GFP_NOFS);
 428                                 if (!ret) {
 429                                         btrfs_release_path(root, path);
 430                                         lock_extent(&BTRFS_I(inode)->io_tree,
 431                                                 locked_end, extent_end - 1,
 432                                                 GFP_NOFS);
 433                                         locked_end = extent_end;
 434                                         continue;
 435                                 }
 436                                 locked_end = extent_end;
 437                         }
 438                         disk_bytenr = le64_to_cpu(old.disk_bytenr);
 439                         if (disk_bytenr != 0) {
 440                                 ret = btrfs_inc_extent_ref(trans, root,
 441                                            disk_bytenr,
 442                                            le64_to_cpu(old.disk_num_bytes), 0,
 443                                            root->root_key.objectid,
 444                                            key.objectid, key.offset -
 445                                            le64_to_cpu(old.offset));
 446                                 BUG_ON(ret);
 447                         }
 448                 }
 449
 450                 if (found_inline) {
 451                         u64 mask = root->sectorsize - 1;
 452                         search_start = (extent_end + mask) & ~mask;
 453                 } else
 454                         search_start = extent_end;
 455
 456                 /* truncate existing extent */
 457                 if (start > key.offset) {
 458                         u64 new_num;
 459                         u64 old_num;
 460                         keep = 1;
 461                         WARN_ON(start & (root->sectorsize - 1));
 462                         if (found_extent) {
 463                                 new_num = start - key.offset;
 464                                 old_num = btrfs_file_extent_num_bytes(leaf,
 465                                                                       extent);
 466                                 *hint_byte =
 467                                         btrfs_file_extent_disk_bytenr(leaf,
 468                                                                       extent);
 469                                 if (btrfs_file_extent_disk_bytenr(leaf,
 470                                                                   extent)) {
 471                                         inode_sub_bytes(inode, old_num -
 472                                                         new_num);
 473                                 }
 474                                 btrfs_set_file_extent_num_bytes(leaf,
 475                                                         extent, new_num);
 476                                 btrfs_mark_buffer_dirty(leaf);
 477                         } else if (key.offset < inline_limit &&
 478                                    (end > extent_end) &&
 479                                    (inline_limit < extent_end)) {
 480                                 u32 new_size;
 481                                 new_size = btrfs_file_extent_calc_inline_size(
 482                                                    inline_limit - key.offset);
 483                                 inode_sub_bytes(inode, extent_end -
 484                                                 inline_limit);
 485                                 btrfs_set_file_extent_ram_bytes(leaf, extent,
 486                                                         new_size);
 487                                 if (!compression && !encryption) {
 488                                         btrfs_truncate_item(trans, root, path,
 489                                                             new_size, 1);
 490                                 }
 491                         }
 492                 }
 493                 /* delete the entire extent */
 494                 if (!keep) {
 495                         if (found_inline)
 496                                 inode_sub_bytes(inode, extent_end -
 497                                                 key.offset);
 498                         ret = btrfs_del_item(trans, root, path);
 499                         /* TODO update progress marker and return */
 500                         BUG_ON(ret);
 501                         extent = NULL;
 502                         btrfs_release_path(root, path);
 503                         /* the extent will be freed later */
 504                 }
 505                 if (bookend && found_inline && start <= key.offset) {
 506                         u32 new_size;
 507                         new_size = btrfs_file_extent_calc_inline_size(
 508                                                    extent_end - end);
 509                         inode_sub_bytes(inode, end - key.offset);
 510                         btrfs_set_file_extent_ram_bytes(leaf, extent,
 511                                                         new_size);
 512                         if (!compression && !encryption)
 513                                 ret = btrfs_truncate_item(trans, root, path,
 514                                                           new_size, 0);
 515                         BUG_ON(ret);
 516                 }
 517                 /* create bookend, splitting the extent in two */
 518                 if (bookend && found_extent) {
 519                         struct btrfs_key ins;
 520                         ins.objectid = inode->i_ino;
 521                         ins.offset = end;
 522                         btrfs_set_key_type(&ins, BTRFS_EXTENT_DATA_KEY);
 523
 524                         btrfs_release_path(root, path);
 525                         path->leave_spinning = 1;
 526                         ret = btrfs_insert_empty_item(trans, root, path, &ins,
 527                                                       sizeof(*extent));
 528                         BUG_ON(ret);
 529
 530                         leaf = path->nodes[0];
 531                         extent = btrfs_item_ptr(leaf, path->slots[0],
 532                                                 struct btrfs_file_extent_item);
 533                         write_extent_buffer(leaf, &old,
 534                                             (unsigned long)extent, sizeof(old));
 535
 536                         btrfs_set_file_extent_compression(leaf, extent,
 537                                                           compression);
 538                         btrfs_set_file_extent_encryption(leaf, extent,
 539                                                          encryption);
 540                         btrfs_set_file_extent_other_encoding(leaf, extent,
 541                                                              other_encoding);
 542                         btrfs_set_file_extent_offset(leaf, extent,
 543                                     le64_to_cpu(old.offset) + end - key.offset);
 544                         WARN_ON(le64_to_cpu(old.num_bytes) <
 545                                 (extent_end - end));
 546                         btrfs_set_file_extent_num_bytes(leaf, extent,
 547                                                         extent_end - end);
 548
 549                         /*
 550                          * set the ram bytes to the size of the full extent
 551                          * before splitting.  This is a worst case flag,
 552                          * but its the best we can do because we don't know
 553                          * how splitting affects compression
 554                          */
 555                         btrfs_set_file_extent_ram_bytes(leaf, extent,
 556                                                         ram_bytes);
 557                         btrfs_set_file_extent_type(leaf, extent, found_type);
 558
 559                         btrfs_unlock_up_safe(path, 1);
 560                         btrfs_mark_buffer_dirty(path->nodes[0]);
 561                         btrfs_set_lock_blocking(path->nodes[0]);
 562
 563                         path->leave_spinning = 0;
 564                         btrfs_release_path(root, path);
 565                         if (disk_bytenr != 0)
 566                                 inode_add_bytes(inode, extent_end - end);
 567                 }
 568
 569                 if (found_extent && !keep) {
 570                         u64 old_disk_bytenr = le64_to_cpu(old.disk_bytenr);
 571
 572                         if (old_disk_bytenr != 0) {
 573                                 inode_sub_bytes(inode,
 574                                                 le64_to_cpu(old.num_bytes));
 575                                 ret = btrfs_free_extent(trans, root,
 576                                                 old_disk_bytenr,
 577                                                 le64_to_cpu(old.disk_num_bytes),
 578                                                 0, root->root_key.objectid,
 579                                                 key.objectid, key.offset -
 580                                                 le64_to_cpu(old.offset));
 581                                 BUG_ON(ret);
 582                                 *hint_byte = old_disk_bytenr;
 583                         }
 584                 }
 585
 586                 if (search_start >= end) {
 587                         ret = 0;
 588                         goto out;
 589                 }
 590         }
 591 out:
 592         btrfs_free_path(path);
 593         if (locked_end > orig_locked_end) {
 594                 unlock_extent(&BTRFS_I(inode)->io_tree, orig_locked_end,
 595                               locked_end - 1, GFP_NOFS);
 596         }
 597         return ret;
 598 }
 599
 600 static int extent_mergeable(struct extent_buffer *leaf, int slot,
 601                             u64 objectid, u64 bytenr, u64 *start, u64 *end)
 602 {
 603         struct btrfs_file_extent_item *fi;
 604         struct btrfs_key key;
 605         u64 extent_end;
 606
 607         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
 608                 return 0;
 609
 610         btrfs_item_key_to_cpu(leaf, &key, slot);
 611         if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
 612                 return 0;
 613
 614         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
 615         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
 616             btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
 617             btrfs_file_extent_compression(leaf, fi) ||
 618             btrfs_file_extent_encryption(leaf, fi) ||
 619             btrfs_file_extent_other_encoding(leaf, fi))
 620                 return 0;
 621
 622         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 623         if ((*start && *start != key.offset) || (*end && *end != extent_end))
 624                 return 0;
 625
 626         *start = key.offset;
 627         *end = extent_end;
 628         return 1;
 629 }
 630
 631 /*
 632  * Mark extent in the range start - end as written.
 633  *
 634  * This changes extent type from 'pre-allocated' to 'regular'. If only
 635  * part of extent is marked as written, the extent will be split into
 636  * two or three.
 637  */
 638 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
 639                               struct btrfs_root *root,
 640                               struct inode *inode, u64 start, u64 end)
 641 {
 642         struct extent_buffer *leaf;
 643         struct btrfs_path *path;
 644         struct btrfs_file_extent_item *fi;
 645         struct btrfs_key key;
 646         u64 bytenr;
 647         u64 num_bytes;
 648         u64 extent_end;
 649         u64 orig_offset;
 650         u64 other_start;
 651         u64 other_end;
 652         u64 split = start;
 653         u64 locked_end = end;
 654         int extent_type;
 655         int split_end = 1;
 656         int ret;
 657
 658         btrfs_drop_extent_cache(inode, start, end - 1, 0);
 659
 660         path = btrfs_alloc_path();
 661         BUG_ON(!path);
 662 again:
 663         key.objectid = inode->i_ino;
 664         key.type = BTRFS_EXTENT_DATA_KEY;
 665         if (split == start)
 666                 key.offset = split;
 667         else
 668                 key.offset = split - 1;
 669
 670         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 671         if (ret > 0 && path->slots[0] > 0)
 672                 path->slots[0]--;
 673
 674         leaf = path->nodes[0];
 675         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 676         BUG_ON(key.objectid != inode->i_ino ||
 677                key.type != BTRFS_EXTENT_DATA_KEY);
 678         fi = btrfs_item_ptr(leaf, path->slots[0],
 679                             struct btrfs_file_extent_item);
 680         extent_type = btrfs_file_extent_type(leaf, fi);
 681         BUG_ON(extent_type != BTRFS_FILE_EXTENT_PREALLOC);
 682         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 683         BUG_ON(key.offset > start || extent_end < end);
 684
 685         bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 686         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
 687         orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
 688
 689         if (key.offset == start)
 690                 split = end;
 691
 692         if (key.offset == start && extent_end == end) {
 693                 int del_nr = 0;
 694                 int del_slot = 0;
 695                 other_start = end;
 696                 other_end = 0;
 697                 if (extent_mergeable(leaf, path->slots[0] + 1, inode->i_ino,
 698                                      bytenr, &other_start, &other_end)) {
 699                         extent_end = other_end;
 700                         del_slot = path->slots[0] + 1;
 701                         del_nr++;
 702                         ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
 703                                                 0, root->root_key.objectid,
 704                                                 inode->i_ino, orig_offset);
 705                         BUG_ON(ret);
 706                 }
 707                 other_start = 0;
 708                 other_end = start;
 709                 if (extent_mergeable(leaf, path->slots[0] - 1, inode->i_ino,
 710                                      bytenr, &other_start, &other_end)) {
 711                         key.offset = other_start;
 712                         del_slot = path->slots[0];
 713                         del_nr++;
 714                         ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
 715                                                 0, root->root_key.objectid,
 716                                                 inode->i_ino, orig_offset);
 717                         BUG_ON(ret);
 718                 }
 719                 split_end = 0;
 720                 if (del_nr == 0) {
 721                         btrfs_set_file_extent_type(leaf, fi,
 722                                                    BTRFS_FILE_EXTENT_REG);
 723                         goto done;
 724                 }
 725
 726                 fi = btrfs_item_ptr(leaf, del_slot - 1,
 727                                     struct btrfs_file_extent_item);
 728                 btrfs_set_file_extent_type(leaf, fi, BTRFS_FILE_EXTENT_REG);
 729                 btrfs_set_file_extent_num_bytes(leaf, fi,
 730                                                 extent_end - key.offset);
 731                 btrfs_mark_buffer_dirty(leaf);
 732
 733                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
 734                 BUG_ON(ret);
 735                 goto release;
 736         } else if (split == start) {
 737                 if (locked_end < extent_end) {
 738                         ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
 739                                         locked_end, extent_end - 1, GFP_NOFS);
 740                         if (!ret) {
 741                                 btrfs_release_path(root, path);
 742                                 lock_extent(&BTRFS_I(inode)->io_tree,
 743                                         locked_end, extent_end - 1, GFP_NOFS);
 744                                 locked_end = extent_end;
 745                                 goto again;
 746                         }
 747                         locked_end = extent_end;
 748                 }
 749                 btrfs_set_file_extent_num_bytes(leaf, fi, split - key.offset);
 750         } else  {
 751                 BUG_ON(key.offset != start);
 752                 key.offset = split;
 753                 btrfs_set_file_extent_offset(leaf, fi, key.offset -
 754                                              orig_offset);
 755                 btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - split);
 756                 btrfs_set_item_key_safe(trans, root, path, &key);
 757                 extent_end = split;
 758         }
 759
 760         if (extent_end == end) {
 761                 split_end = 0;
 762                 extent_type = BTRFS_FILE_EXTENT_REG;
 763         }
 764         if (extent_end == end && split == start) {
 765                 other_start = end;
 766                 other_end = 0;
 767                 if (extent_mergeable(leaf, path->slots[0] + 1, inode->i_ino,
 768                                      bytenr, &other_start, &other_end)) {
 769                         path->slots[0]++;
 770                         fi = btrfs_item_ptr(leaf, path->slots[0],
 771                                             struct btrfs_file_extent_item);
 772                         key.offset = split;
 773                         btrfs_set_item_key_safe(trans, root, path, &key);
 774                         btrfs_set_file_extent_offset(leaf, fi, key.offset -
 775                                                      orig_offset);
 776                         btrfs_set_file_extent_num_bytes(leaf, fi,
 777                                                         other_end - split);
 778                         goto done;
 779                 }
 780         }
 781         if (extent_end == end && split == end) {
 782                 other_start = 0;
 783                 other_end = start;
 784                 if (extent_mergeable(leaf, path->slots[0] - 1 , inode->i_ino,
 785                                      bytenr, &other_start, &other_end)) {
 786                         path->slots[0]--;
 787                         fi = btrfs_item_ptr(leaf, path->slots[0],
 788                                             struct btrfs_file_extent_item);
 789                         btrfs_set_file_extent_num_bytes(leaf, fi, extent_end -
 790                                                         other_start);
 791                         goto done;
 792                 }
 793         }
 794
 795         btrfs_mark_buffer_dirty(leaf);
 796
 797         ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
 798                                    root->root_key.objectid,
 799                                    inode->i_ino, orig_offset);
 800         BUG_ON(ret);
 801         btrfs_release_path(root, path);
 802
 803         key.offset = start;
 804         ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*fi));
 805         BUG_ON(ret);
 806
 807         leaf = path->nodes[0];
 808         fi = btrfs_item_ptr(leaf, path->slots[0],
 809                             struct btrfs_file_extent_item);
 810         btrfs_set_file_extent_generation(leaf, fi, trans->transid);
 811         btrfs_set_file_extent_type(leaf, fi, extent_type);
 812         btrfs_set_file_extent_disk_bytenr(leaf, fi, bytenr);
 813         btrfs_set_file_extent_disk_num_bytes(leaf, fi, num_bytes);
 814         btrfs_set_file_extent_offset(leaf, fi, key.offset - orig_offset);
 815         btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - key.offset);
 816         btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
 817         btrfs_set_file_extent_compression(leaf, fi, 0);
 818         btrfs_set_file_extent_encryption(leaf, fi, 0);
 819         btrfs_set_file_extent_other_encoding(leaf, fi, 0);
 820 done:
 821         btrfs_mark_buffer_dirty(leaf);
 822
 823 release:
 824         btrfs_release_path(root, path);
 825         if (split_end && split == start) {
 826                 split = end;
 827                 goto again;
 828         }
 829         if (locked_end > end) {
 830                 unlock_extent(&BTRFS_I(inode)->io_tree, end, locked_end - 1,
 831                               GFP_NOFS);
 832         }
 833         btrfs_free_path(path);
 834         return 0;
 835 }
 836
 837 /*
 838  * this gets pages into the page cache and locks them down, it also properly
 839  * waits for data=ordered extents to finish before allowing the pages to be
 840  * modified.
 841  */
 842 static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
 843                          struct page **pages, size_t num_pages,
 844                          loff_t pos, unsigned long first_index,
 845                          unsigned long last_index, size_t write_bytes)
 846 {
 847         int i;
 848         unsigned long index = pos >> PAGE_CACHE_SHIFT;
 849         struct inode *inode = fdentry(file)->d_inode;
 850         int err = 0;
 851         u64 start_pos;
 852         u64 last_pos;
 853
 854         start_pos = pos & ~((u64)root->sectorsize - 1);
 855         last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
 856
 857         if (start_pos > inode->i_size) {
 858                 err = btrfs_cont_expand(inode, start_pos);
 859                 if (err)
 860                         return err;
 861         }
 862
 863         memset(pages, 0, num_pages * sizeof(struct page *));
 864 again:
 865         for (i = 0; i < num_pages; i++) {
 866                 pages[i] = grab_cache_page(inode->i_mapping, index + i);
 867                 if (!pages[i]) {
 868                         err = -ENOMEM;
 869                         BUG_ON(1);
 870                 }
 871                 wait_on_page_writeback(pages[i]);
 872         }
 873         if (start_pos < inode->i_size) {
 874                 struct btrfs_ordered_extent *ordered;
 875                 lock_extent(&BTRFS_I(inode)->io_tree,
 876                             start_pos, last_pos - 1, GFP_NOFS);
 877                 ordered = btrfs_lookup_first_ordered_extent(inode,
 878                                                             last_pos - 1);
 879                 if (ordered &&
 880                     ordered->file_offset + ordered->len > start_pos &&
 881                     ordered->file_offset < last_pos) {
 882                         btrfs_put_ordered_extent(ordered);
 883                         unlock_extent(&BTRFS_I(inode)->io_tree,
 884                                       start_pos, last_pos - 1, GFP_NOFS);
 885                         for (i = 0; i < num_pages; i++) {
 886                                 unlock_page(pages[i]);
 887                                 page_cache_release(pages[i]);
 888                         }
 889                         btrfs_wait_ordered_range(inode, start_pos,
 890                                                  last_pos - start_pos);
 891                         goto again;
 892                 }
 893                 if (ordered)
 894                         btrfs_put_ordered_extent(ordered);
 895
 896                 clear_extent_bits(&BTRFS_I(inode)->io_tree, start_pos,
 897                                   last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC,
 898                                   GFP_NOFS);
 899                 unlock_extent(&BTRFS_I(inode)->io_tree,
 900                               start_pos, last_pos - 1, GFP_NOFS);
 901         }
 902         for (i = 0; i < num_pages; i++) {
 903                 clear_page_dirty_for_io(pages[i]);
 904                 set_page_extent_mapped(pages[i]);
 905                 WARN_ON(!PageLocked(pages[i]));
 906         }
 907         return 0;
 908 }
 909
 910 static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
 911                                 size_t count, loff_t *ppos)
 912 {
 913         loff_t pos;
 914         loff_t start_pos;
 915         ssize_t num_written = 0;
 916         ssize_t err = 0;
 917         int ret = 0;
 918         struct inode *inode = fdentry(file)->d_inode;
 919         struct btrfs_root *root = BTRFS_I(inode)->root;
 920         struct page **pages = NULL;
 921         int nrptrs;
 922         struct page *pinned[2];
 923         unsigned long first_index;
 924         unsigned long last_index;
 925         int will_write;
 926
 927         will_write = ((file->f_flags & O_SYNC) || IS_SYNC(inode) ||
 928                       (file->f_flags & O_DIRECT));
 929
 930         nrptrs = min((count + PAGE_CACHE_SIZE - 1) / PAGE_CACHE_SIZE,
 931                      PAGE_CACHE_SIZE / (sizeof(struct page *)));
 932         pinned[0] = NULL;
 933         pinned[1] = NULL;
 934
 935         pos = *ppos;
 936         start_pos = pos;
 937
 938         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
 939         current->backing_dev_info = inode->i_mapping->backing_dev_info;
 940         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
 941         if (err)
 942                 goto out_nolock;
 943         if (count == 0)
 944                 goto out_nolock;
 945
 946         err = file_remove_suid(file);
 947         if (err)
 948                 goto out_nolock;
 949         file_update_time(file);
 950
 951         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
 952
 953         mutex_lock(&inode->i_mutex);
 954         BTRFS_I(inode)->sequence++;
 955         first_index = pos >> PAGE_CACHE_SHIFT;
 956         last_index = (pos + count) >> PAGE_CACHE_SHIFT;
 957
 958         /*
 959          * there are lots of better ways to do this, but this code
 960          * makes sure the first and last page in the file range are
 961          * up to date and ready for cow
 962          */
 963         if ((pos & (PAGE_CACHE_SIZE - 1))) {
 964                 pinned[0] = grab_cache_page(inode->i_mapping, first_index);
 965                 if (!PageUptodate(pinned[0])) {
 966                         ret = btrfs_readpage(NULL, pinned[0]);
 967                         BUG_ON(ret);
 968                         wait_on_page_locked(pinned[0]);
 969                 } else {
 970                         unlock_page(pinned[0]);
 971                 }
 972         }
 973         if ((pos + count) & (PAGE_CACHE_SIZE - 1)) {
 974                 pinned[1] = grab_cache_page(inode->i_mapping, last_index);
 975                 if (!PageUptodate(pinned[1])) {
 976                         ret = btrfs_readpage(NULL, pinned[1]);
 977                         BUG_ON(ret);
 978                         wait_on_page_locked(pinned[1]);
 979                 } else {
 980                         unlock_page(pinned[1]);
 981                 }
 982         }
 983
 984         while (count > 0) {
 985                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
 986                 size_t write_bytes = min(count, nrptrs *
 987                                         (size_t)PAGE_CACHE_SIZE -
 988                                          offset);
 989                 size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
 990                                         PAGE_CACHE_SHIFT;
 991
 992                 WARN_ON(num_pages > nrptrs);
 993                 memset(pages, 0, sizeof(struct page *) * nrptrs);
 994
 995                 ret = btrfs_check_data_free_space(root, inode, write_bytes);
 996                 if (ret)
 997                         goto out;
 998
 999                 ret = prepare_pages(root, file, pages, num_pages,
1000                                     pos, first_index, last_index,
1001                                     write_bytes);
1002                 if (ret) {
1003                         btrfs_free_reserved_data_space(root, inode,
1004                                                        write_bytes);
1005                         goto out;
1006                 }
1007
1008                 ret = btrfs_copy_from_user(pos, num_pages,
1009                                            write_bytes, pages, buf);
1010                 if (ret) {
1011                         btrfs_free_reserved_data_space(root, inode,
1012                                                        write_bytes);
1013                         btrfs_drop_pages(pages, num_pages);
1014                         goto out;
1015                 }
1016
1017                 ret = dirty_and_release_pages(NULL, root, file, pages,
1018                                               num_pages, pos, write_bytes);
1019                 btrfs_drop_pages(pages, num_pages);
1020                 if (ret) {
1021                         btrfs_free_reserved_data_space(root, inode,
1022                                                        write_bytes);
1023                         goto out;
1024                 }
1025
1026                 if (will_write) {
1027                         btrfs_fdatawrite_range(inode->i_mapping, pos,
1028                                                pos + write_bytes - 1,
1029                                                WB_SYNC_ALL);
1030                 } else {
1031                         balance_dirty_pages_ratelimited_nr(inode->i_mapping,
1032                                                            num_pages);
1033                         if (num_pages <
1034                             (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
1035                                 btrfs_btree_balance_dirty(root, 1);
1036                         btrfs_throttle(root);
1037                 }
1038
1039                 buf += write_bytes;
1040                 count -= write_bytes;
1041                 pos += write_bytes;
1042                 num_written += write_bytes;
1043
1044                 cond_resched();
1045         }
1046 out:
1047         mutex_unlock(&inode->i_mutex);
1048         if (ret)
1049                 err = ret;
1050
1051 out_nolock:
1052         kfree(pages);
1053         if (pinned[0])
1054                 page_cache_release(pinned[0]);
1055         if (pinned[1])
1056                 page_cache_release(pinned[1]);
1057         *ppos = pos;
1058
1059         /*
1060          * we want to make sure fsync finds this change
1061          * but we haven't joined a transaction running right now.
1062          *
1063          * Later on, someone is sure to update the inode and get the
1064          * real transid recorded.
1065          *
1066          * We set last_trans now to the fs_info generation + 1,
1067          * this will either be one more than the running transaction
1068          * or the generation used for the next transaction if there isn't
1069          * one running right now.
1070          */
1071         BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
1072
1073         if (num_written > 0 && will_write) {
1074                 struct btrfs_trans_handle *trans;
1075
1076                 err = btrfs_wait_ordered_range(inode, start_pos, num_written);
1077                 if (err)
1078                         num_written = err;
1079
1080                 if ((file->f_flags & O_SYNC) || IS_SYNC(inode)) {
1081                         trans = btrfs_start_transaction(root, 1);
1082                         ret = btrfs_log_dentry_safe(trans, root,
1083                                                     file->f_dentry);
1084                         if (ret == 0) {
1085                                 ret = btrfs_sync_log(trans, root);
1086                                 if (ret == 0)
1087                                         btrfs_end_transaction(trans, root);
1088                                 else
1089                                         btrfs_commit_transaction(trans, root);
1090                         } else {
1091                                 btrfs_commit_transaction(trans, root);
1092                         }
1093                 }
1094                 if (file->f_flags & O_DIRECT) {
1095                         invalidate_mapping_pages(inode->i_mapping,
1096                               start_pos >> PAGE_CACHE_SHIFT,
1097                              (start_pos + num_written - 1) >> PAGE_CACHE_SHIFT);
1098                 }
1099         }
1100         current->backing_dev_info = NULL;
1101         return num_written ? num_written : err;
1102 }
1103
1104 int btrfs_release_file(struct inode *inode, struct file *filp)
1105 {
1106         /*
1107          * ordered_data_close is set by settattr when we are about to truncate
1108          * a file from a non-zero size to a zero size.  This tries to
1109          * flush down new bytes that may have been written if the
1110          * application were using truncate to replace a file in place.
1111          */
1112         if (BTRFS_I(inode)->ordered_data_close) {
1113                 BTRFS_I(inode)->ordered_data_close = 0;
1114                 btrfs_add_ordered_operation(NULL, BTRFS_I(inode)->root, inode);
1115                 if (inode->i_size > BTRFS_ORDERED_OPERATIONS_FLUSH_LIMIT)
1116                         filemap_flush(inode->i_mapping);
1117         }
1118         if (filp->private_data)
1119                 btrfs_ioctl_trans_end(filp);
1120         return 0;
1121 }
1122
1123 /*
1124  * fsync call for both files and directories.  This logs the inode into
1125  * the tree log instead of forcing full commits whenever possible.
1126  *
1127  * It needs to call filemap_fdatawait so that all ordered extent updates are
1128  * in the metadata btree are up to date for copying to the log.
1129  *
1130  * It drops the inode mutex before doing the tree log commit.  This is an
1131  * important optimization for directories because holding the mutex prevents
1132  * new operations on the dir while we write to disk.
1133  */
1134 int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
1135 {
1136         struct inode *inode = dentry->d_inode;
1137         struct btrfs_root *root = BTRFS_I(inode)->root;
1138         int ret = 0;
1139         struct btrfs_trans_handle *trans;
1140
1141         /*
1142          * check the transaction that last modified this inode
1143          * and see if its already been committed
1144          */
1145         if (!BTRFS_I(inode)->last_trans)
1146                 goto out;
1147
1148         mutex_lock(&root->fs_info->trans_mutex);
1149         if (BTRFS_I(inode)->last_trans <=
1150             root->fs_info->last_trans_committed) {
1151                 BTRFS_I(inode)->last_trans = 0;
1152                 mutex_unlock(&root->fs_info->trans_mutex);
1153                 goto out;
1154         }
1155         mutex_unlock(&root->fs_info->trans_mutex);
1156
1157         root->log_batch++;
1158         filemap_fdatawrite(inode->i_mapping);
1159         btrfs_wait_ordered_range(inode, 0, (u64)-1);
1160         root->log_batch++;
1161
1162         if (datasync && !(inode->i_state & I_DIRTY_PAGES))
1163                 goto out;
1164         /*
1165          * ok we haven't committed the transaction yet, lets do a commit
1166          */
1167         if (file && file->private_data)
1168                 btrfs_ioctl_trans_end(file);
1169
1170         trans = btrfs_start_transaction(root, 1);
1171         if (!trans) {
1172                 ret = -ENOMEM;
1173                 goto out;
1174         }
1175
1176         ret = btrfs_log_dentry_safe(trans, root, dentry);
1177         if (ret < 0)
1178                 goto out;
1179
1180         /* we've logged all the items and now have a consistent
1181          * version of the file in the log.  It is possible that
1182          * someone will come in and modify the file, but that's
1183          * fine because the log is consistent on disk, and we
1184          * have references to all of the file's extents
1185          *
1186          * It is possible that someone will come in and log the
1187          * file again, but that will end up using the synchronization
1188          * inside btrfs_sync_log to keep things safe.
1189          */
1190         mutex_unlock(&dentry->d_inode->i_mutex);
1191
1192         if (ret > 0) {
1193                 ret = btrfs_commit_transaction(trans, root);
1194         } else {
1195                 ret = btrfs_sync_log(trans, root);
1196                 if (ret == 0)
1197                         ret = btrfs_end_transaction(trans, root);
1198                 else
1199                         ret = btrfs_commit_transaction(trans, root);
1200         }
1201         mutex_lock(&dentry->d_inode->i_mutex);
1202 out:
1203         return ret > 0 ? EIO : ret;
1204 }
1205
1206 static struct vm_operations_struct btrfs_file_vm_ops = {
1207         .fault          = filemap_fault,
1208         .page_mkwrite   = btrfs_page_mkwrite,
1209 };
1210
1211 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
1212 {
1213         vma->vm_ops = &btrfs_file_vm_ops;
1214         file_accessed(filp);
1215         return 0;
1216 }
1217
1218 struct file_operations btrfs_file_operations = {
1219         .llseek         = generic_file_llseek,
1220         .read           = do_sync_read,
1221         .aio_read       = generic_file_aio_read,
1222         .splice_read    = generic_file_splice_read,
1223         .write          = btrfs_file_write,
1224         .mmap           = btrfs_file_mmap,
1225         .open           = generic_file_open,
1226         .release        = btrfs_release_file,
1227         .fsync          = btrfs_sync_file,
1228         .unlocked_ioctl = btrfs_ioctl,
1229 #ifdef CONFIG_COMPAT
1230         .compat_ioctl   = btrfs_ioctl,
1231 #endif
1232 };