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