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   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/fs.h>
  20 #include <linux/pagemap.h>
  21 #include <linux/highmem.h>
  22 #include <linux/time.h>
  23 #include <linux/init.h>
  24 #include <linux/string.h>
  25 #include <linux/smp_lock.h>
  26 #include <linux/backing-dev.h>
  27 #include <linux/mpage.h>
  28 #include <linux/swap.h>
  29 #include <linux/writeback.h>
  30 #include <linux/statfs.h>
  31 #include <linux/compat.h>
  32 #include "ctree.h"
  33 #include "disk-io.h"
  34 #include "transaction.h"
  35 #include "btrfs_inode.h"
  36 #include "ioctl.h"
  37 #include "print-tree.h"
  38 #include "tree-log.h"
  39 #include "locking.h"
  40 #include "compat.h"
  41
  42
  43 /* simple helper to fault in pages and copy.  This should go away
  44  * and be replaced with calls into generic code.
  45  */
  46 static noinline int btrfs_copy_from_user(loff_t pos, int num_pages,
  47                                          int write_bytes,
  48                                          struct page **prepared_pages,
  49                                          const char __user *buf)
  50 {
  51         long page_fault = 0;
  52         int i;
  53         int offset = pos & (PAGE_CACHE_SIZE - 1);
  54
  55         for (i = 0; i < num_pages && write_bytes > 0; i++, offset = 0) {
  56                 size_t count = min_t(size_t,
  57                                      PAGE_CACHE_SIZE - offset, write_bytes);
  58                 struct page *page = prepared_pages[i];
  59                 fault_in_pages_readable(buf, count);
  60
  61                 /* Copy data from userspace to the current page */
  62                 kmap(page);
  63                 page_fault = __copy_from_user(page_address(page) + offset,
  64                                               buf, count);
  65                 /* Flush processor's dcache for this page */
  66                 flush_dcache_page(page);
  67                 kunmap(page);
  68                 buf += count;
  69                 write_bytes -= count;
  70
  71                 if (page_fault)
  72                         break;
  73         }
  74         return page_fault ? -EFAULT : 0;
  75 }
  76
  77 /*
  78  * unlocks pages after btrfs_file_write is done with them
  79  */
  80 static noinline void btrfs_drop_pages(struct page **pages, size_t num_pages)
  81 {
  82         size_t i;
  83         for (i = 0; i < num_pages; i++) {
  84                 if (!pages[i])
  85                         break;
  86                 /* page checked is some magic around finding pages that
  87                  * have been modified without going through btrfs_set_page_dirty
  88                  * clear it here
  89                  */
  90                 ClearPageChecked(pages[i]);
  91                 unlock_page(pages[i]);
  92                 mark_page_accessed(pages[i]);
  93                 page_cache_release(pages[i]);
  94         }
  95 }
  96
  97 /*
  98  * after copy_from_user, pages need to be dirtied and we need to make
  99  * sure holes are created between the current EOF and the start of
 100  * any next extents (if required).
 101  *
 102  * this also makes the decision about creating an inline extent vs
 103  * doing real data extents, marking pages dirty and delalloc as required.
 104  */
 105 static noinline int dirty_and_release_pages(struct btrfs_trans_handle *trans,
 106                                    struct btrfs_root *root,
 107                                    struct file *file,
 108                                    struct page **pages,
 109                                    size_t num_pages,
 110                                    loff_t pos,
 111                                    size_t write_bytes)
 112 {
 113         int err = 0;
 114         int i;
 115         struct inode *inode = fdentry(file)->d_inode;
 116         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 117         u64 hint_byte;
 118         u64 num_bytes;
 119         u64 start_pos;
 120         u64 end_of_last_block;
 121         u64 end_pos = pos + write_bytes;
 122         loff_t isize = i_size_read(inode);
 123
 124         start_pos = pos & ~((u64)root->sectorsize - 1);
 125         num_bytes = (write_bytes + pos - start_pos +
 126                     root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
 127
 128         end_of_last_block = start_pos + num_bytes - 1;
 129
 130         lock_extent(io_tree, start_pos, end_of_last_block, GFP_NOFS);
 131         trans = btrfs_join_transaction(root, 1);
 132         if (!trans) {
 133                 err = -ENOMEM;
 134                 goto out_unlock;
 135         }
 136         btrfs_set_trans_block_group(trans, inode);
 137         hint_byte = 0;
 138
 139         set_extent_uptodate(io_tree, start_pos, end_of_last_block, GFP_NOFS);
 140
 141         /* check for reserved extents on each page, we don't want
 142          * to reset the delalloc bit on things that already have
 143          * extents reserved.
 144          */
 145         btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block);
 146         for (i = 0; i < num_pages; i++) {
 147                 struct page *p = pages[i];
 148                 SetPageUptodate(p);
 149                 ClearPageChecked(p);
 150                 set_page_dirty(p);
 151         }
 152         if (end_pos > isize) {
 153                 i_size_write(inode, end_pos);
 154                 btrfs_update_inode(trans, root, inode);
 155         }
 156         err = btrfs_end_transaction(trans, root);
 157 out_unlock:
 158         unlock_extent(io_tree, start_pos, end_of_last_block, GFP_NOFS);
 159         return err;
 160 }
 161
 162 /*
 163  * this drops all the extents in the cache that intersect the range
 164  * [start, end].  Existing extents are split as required.
 165  */
 166 int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
 167                             int skip_pinned)
 168 {
 169         struct extent_map *em;
 170         struct extent_map *split = NULL;
 171         struct extent_map *split2 = NULL;
 172         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
 173         u64 len = end - start + 1;
 174         int ret;
 175         int testend = 1;
 176         unsigned long flags;
 177         int compressed = 0;
 178
 179         WARN_ON(end < start);
 180         if (end == (u64)-1) {
 181                 len = (u64)-1;
 182                 testend = 0;
 183         }
 184         while (1) {
 185                 if (!split)
 186                         split = alloc_extent_map(GFP_NOFS);
 187                 if (!split2)
 188                         split2 = alloc_extent_map(GFP_NOFS);
 189
 190                 spin_lock(&em_tree->lock);
 191                 em = lookup_extent_mapping(em_tree, start, len);
 192                 if (!em) {
 193                         spin_unlock(&em_tree->lock);
 194                         break;
 195                 }
 196                 flags = em->flags;
 197                 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
 198                         spin_unlock(&em_tree->lock);
 199                         if (em->start <= start &&
 200                             (!testend || em->start + em->len >= start + len)) {
 201                                 free_extent_map(em);
 202                                 break;
 203                         }
 204                         if (start < em->start) {
 205                                 len = em->start - start;
 206                         } else {
 207                                 len = start + len - (em->start + em->len);
 208                                 start = em->start + em->len;
 209                         }
 210                         free_extent_map(em);
 211                         continue;
 212                 }
 213                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 214                 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
 215                 remove_extent_mapping(em_tree, em);
 216
 217                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 218                     em->start < start) {
 219                         split->start = em->start;
 220                         split->len = start - em->start;
 221                         split->orig_start = em->orig_start;
 222                         split->block_start = em->block_start;
 223
 224                         if (compressed)
 225                                 split->block_len = em->block_len;
 226                         else
 227                                 split->block_len = split->len;
 228
 229                         split->bdev = em->bdev;
 230                         split->flags = flags;
 231                         ret = add_extent_mapping(em_tree, split);
 232                         BUG_ON(ret);
 233                         free_extent_map(split);
 234                         split = split2;
 235                         split2 = NULL;
 236                 }
 237                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 238                     testend && em->start + em->len > start + len) {
 239                         u64 diff = start + len - em->start;
 240
 241                         split->start = start + len;
 242                         split->len = em->start + em->len - (start + len);
 243                         split->bdev = em->bdev;
 244                         split->flags = flags;
 245
 246                         if (compressed) {
 247                                 split->block_len = em->block_len;
 248                                 split->block_start = em->block_start;
 249                                 split->orig_start = em->orig_start;
 250                         } else {
 251                                 split->block_len = split->len;
 252                                 split->block_start = em->block_start + diff;
 253                                 split->orig_start = split->start;
 254                         }
 255
 256                         ret = add_extent_mapping(em_tree, split);
 257                         BUG_ON(ret);
 258                         free_extent_map(split);
 259                         split = NULL;
 260                 }
 261                 spin_unlock(&em_tree->lock);
 262
 263                 /* once for us */
 264                 free_extent_map(em);
 265                 /* once for the tree*/
 266                 free_extent_map(em);
 267         }
 268         if (split)
 269                 free_extent_map(split);
 270         if (split2)
 271                 free_extent_map(split2);
 272         return 0;
 273 }
 274
 275 int btrfs_check_file(struct btrfs_root *root, struct inode *inode)
 276 {
 277         return 0;
 278 #if 0
 279         struct btrfs_path *path;
 280         struct btrfs_key found_key;
 281         struct extent_buffer *leaf;
 282         struct btrfs_file_extent_item *extent;
 283         u64 last_offset = 0;
 284         int nritems;
 285         int slot;
 286         int found_type;
 287         int ret;
 288         int err = 0;
 289         u64 extent_end = 0;
 290
 291         path = btrfs_alloc_path();
 292         ret = btrfs_lookup_file_extent(NULL, root, path, inode->i_ino,
 293                                        last_offset, 0);
 294         while (1) {
 295                 nritems = btrfs_header_nritems(path->nodes[0]);
 296                 if (path->slots[0] >= nritems) {
 297                         ret = btrfs_next_leaf(root, path);
 298                         if (ret)
 299                                 goto out;
 300                         nritems = btrfs_header_nritems(path->nodes[0]);
 301                 }
 302                 slot = path->slots[0];
 303                 leaf = path->nodes[0];
 304                 btrfs_item_key_to_cpu(leaf, &found_key, slot);
 305                 if (found_key.objectid != inode->i_ino)
 306                         break;
 307                 if (found_key.type != BTRFS_EXTENT_DATA_KEY)
 308                         goto out;
 309
 310                 if (found_key.offset < last_offset) {
 311                         WARN_ON(1);
 312                         btrfs_print_leaf(root, leaf);
 313                         printk(KERN_ERR "inode %lu found offset %llu "
 314                                "expected %llu\n", inode->i_ino,
 315                                (unsigned long long)found_key.offset,
 316                                (unsigned long long)last_offset);
 317                         err = 1;
 318                         goto out;
 319                 }
 320                 extent = btrfs_item_ptr(leaf, slot,
 321                                         struct btrfs_file_extent_item);
 322                 found_type = btrfs_file_extent_type(leaf, extent);
 323                 if (found_type == BTRFS_FILE_EXTENT_REG) {
 324                         extent_end = found_key.offset +
 325                              btrfs_file_extent_num_bytes(leaf, extent);
 326                 } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
 327                         struct btrfs_item *item;
 328                         item = btrfs_item_nr(leaf, slot);
 329                         extent_end = found_key.offset +
 330                              btrfs_file_extent_inline_len(leaf, extent);
 331                         extent_end = (extent_end + root->sectorsize - 1) &
 332                                 ~((u64)root->sectorsize - 1);
 333                 }
 334                 last_offset = extent_end;
 335                 path->slots[0]++;
 336         }
 337         if (0 && last_offset < inode->i_size) {
 338                 WARN_ON(1);
 339                 btrfs_print_leaf(root, leaf);
 340                 printk(KERN_ERR "inode %lu found offset %llu size %llu\n",
 341                        inode->i_ino, (unsigned long long)last_offset,
 342                        (unsigned long long)inode->i_size);
 343                 err = 1;
 344
 345         }
 346 out:
 347         btrfs_free_path(path);
 348         return err;
 349 #endif
 350 }
 351
 352 /*
 353  * this is very complex, but the basic idea is to drop all extents
 354  * in the range start - end.  hint_block is filled in with a block number
 355  * that would be a good hint to the block allocator for this file.
 356  *
 357  * If an extent intersects the range but is not entirely inside the range
 358  * it is either truncated or split.  Anything entirely inside the range
 359  * is deleted from the tree.
 360  *
 361  * inline_limit is used to tell this code which offsets in the file to keep
 362  * if they contain inline extents.
 363  */
 364 noinline int btrfs_drop_extents(struct btrfs_trans_handle *trans,
 365                        struct btrfs_root *root, struct inode *inode,
 366                        u64 start, u64 end, u64 locked_end,
 367                        u64 inline_limit, u64 *hint_byte)
 368 {
 369         u64 extent_end = 0;
 370         u64 search_start = start;
 371         u64 leaf_start;
 372         u64 ram_bytes = 0;
 373         u64 orig_parent = 0;
 374         u64 disk_bytenr = 0;
 375         u64 orig_locked_end = locked_end;
 376         u8 compression;
 377         u8 encryption;
 378         u16 other_encoding = 0;
 379         u64 root_gen;
 380         u64 root_owner;
 381         struct extent_buffer *leaf;
 382         struct btrfs_file_extent_item *extent;
 383         struct btrfs_path *path;
 384         struct btrfs_key key;
 385         struct btrfs_file_extent_item old;
 386         int keep;
 387         int slot;
 388         int bookend;
 389         int found_type = 0;
 390         int found_extent;
 391         int found_inline;
 392         int recow;
 393         int ret;
 394
 395         inline_limit = 0;
 396         btrfs_drop_extent_cache(inode, start, end - 1, 0);
 397
 398         path = btrfs_alloc_path();
 399         if (!path)
 400                 return -ENOMEM;
 401         while (1) {
 402                 recow = 0;
 403                 btrfs_release_path(root, path);
 404                 ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
 405                                                search_start, -1);
 406                 if (ret < 0)
 407                         goto out;
 408                 if (ret > 0) {
 409                         if (path->slots[0] == 0) {
 410                                 ret = 0;
 411                                 goto out;
 412                         }
 413                         path->slots[0]--;
 414                 }
 415 next_slot:
 416                 keep = 0;
 417                 bookend = 0;
 418                 found_extent = 0;
 419                 found_inline = 0;
 420                 leaf_start = 0;
 421                 root_gen = 0;
 422                 root_owner = 0;
 423                 compression = 0;
 424                 encryption = 0;
 425                 extent = NULL;
 426                 leaf = path->nodes[0];
 427                 slot = path->slots[0];
 428                 ret = 0;
 429                 btrfs_item_key_to_cpu(leaf, &key, slot);
 430                 if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY &&
 431                     key.offset >= end) {
 432                         goto out;
 433                 }
 434                 if (btrfs_key_type(&key) > BTRFS_EXTENT_DATA_KEY ||
 435                     key.objectid != inode->i_ino) {
 436                         goto out;
 437                 }
 438                 if (recow) {
 439                         search_start = max(key.offset, start);
 440                         continue;
 441                 }
 442                 if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY) {
 443                         extent = btrfs_item_ptr(leaf, slot,
 444                                                 struct btrfs_file_extent_item);
 445                         found_type = btrfs_file_extent_type(leaf, extent);
 446                         compression = btrfs_file_extent_compression(leaf,
 447                                                                     extent);
 448                         encryption = btrfs_file_extent_encryption(leaf,
 449                                                                   extent);
 450                         other_encoding = btrfs_file_extent_other_encoding(leaf,
 451                                                                   extent);
 452                         if (found_type == BTRFS_FILE_EXTENT_REG ||
 453                             found_type == BTRFS_FILE_EXTENT_PREALLOC) {
 454                                 extent_end =
 455                                      btrfs_file_extent_disk_bytenr(leaf,
 456                                                                    extent);
 457                                 if (extent_end)
 458                                         *hint_byte = extent_end;
 459
 460                                 extent_end = key.offset +
 461                                      btrfs_file_extent_num_bytes(leaf, extent);
 462                                 ram_bytes = btrfs_file_extent_ram_bytes(leaf,
 463                                                                 extent);
 464                                 found_extent = 1;
 465                         } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
 466                                 found_inline = 1;
 467                                 extent_end = key.offset +
 468                                      btrfs_file_extent_inline_len(leaf, extent);
 469                         }
 470                 } else {
 471                         extent_end = search_start;
 472                 }
 473
 474                 /* we found nothing we can drop */
 475                 if ((!found_extent && !found_inline) ||
 476                     search_start >= extent_end) {
 477                         int nextret;
 478                         u32 nritems;
 479                         nritems = btrfs_header_nritems(leaf);
 480                         if (slot >= nritems - 1) {
 481                                 nextret = btrfs_next_leaf(root, path);
 482                                 if (nextret)
 483                                         goto out;
 484                                 recow = 1;
 485                         } else {
 486                                 path->slots[0]++;
 487                         }
 488                         goto next_slot;
 489                 }
 490
 491                 if (end <= extent_end && start >= key.offset && found_inline)
 492                         *hint_byte = EXTENT_MAP_INLINE;
 493
 494                 if (found_extent) {
 495                         read_extent_buffer(leaf, &old, (unsigned long)extent,
 496                                            sizeof(old));
 497                         root_gen = btrfs_header_generation(leaf);
 498                         root_owner = btrfs_header_owner(leaf);
 499                         leaf_start = leaf->start;
 500                 }
 501
 502                 if (end < extent_end && end >= key.offset) {
 503                         bookend = 1;
 504                         if (found_inline && start <= key.offset)
 505                                 keep = 1;
 506                 }
 507
 508                 if (bookend && found_extent) {
 509                         if (locked_end < extent_end) {
 510                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
 511                                                 locked_end, extent_end - 1,
 512                                                 GFP_NOFS);
 513                                 if (!ret) {
 514                                         btrfs_release_path(root, path);
 515                                         lock_extent(&BTRFS_I(inode)->io_tree,
 516                                                 locked_end, extent_end - 1,
 517                                                 GFP_NOFS);
 518                                         locked_end = extent_end;
 519                                         continue;
 520                                 }
 521                                 locked_end = extent_end;
 522                         }
 523                         orig_parent = path->nodes[0]->start;
 524                         disk_bytenr = le64_to_cpu(old.disk_bytenr);
 525                         if (disk_bytenr != 0) {
 526                                 ret = btrfs_inc_extent_ref(trans, root,
 527                                            disk_bytenr,
 528                                            le64_to_cpu(old.disk_num_bytes),
 529                                            orig_parent, root->root_key.objectid,
 530                                            trans->transid, inode->i_ino);
 531                                 BUG_ON(ret);
 532                         }
 533                 }
 534
 535                 if (found_inline) {
 536                         u64 mask = root->sectorsize - 1;
 537                         search_start = (extent_end + mask) & ~mask;
 538                 } else
 539                         search_start = extent_end;
 540
 541                 /* truncate existing extent */
 542                 if (start > key.offset) {
 543                         u64 new_num;
 544                         u64 old_num;
 545                         keep = 1;
 546                         WARN_ON(start & (root->sectorsize - 1));
 547                         if (found_extent) {
 548                                 new_num = start - key.offset;
 549                                 old_num = btrfs_file_extent_num_bytes(leaf,
 550                                                                       extent);
 551                                 *hint_byte =
 552                                         btrfs_file_extent_disk_bytenr(leaf,
 553                                                                       extent);
 554                                 if (btrfs_file_extent_disk_bytenr(leaf,
 555                                                                   extent)) {
 556                                         inode_sub_bytes(inode, old_num -
 557                                                         new_num);
 558                                 }
 559                                 btrfs_set_file_extent_num_bytes(leaf,
 560                                                         extent, new_num);
 561                                 btrfs_mark_buffer_dirty(leaf);
 562                         } else if (key.offset < inline_limit &&
 563                                    (end > extent_end) &&
 564                                    (inline_limit < extent_end)) {
 565                                 u32 new_size;
 566                                 new_size = btrfs_file_extent_calc_inline_size(
 567                                                    inline_limit - key.offset);
 568                                 inode_sub_bytes(inode, extent_end -
 569                                                 inline_limit);
 570                                 btrfs_set_file_extent_ram_bytes(leaf, extent,
 571                                                         new_size);
 572                                 if (!compression && !encryption) {
 573                                         btrfs_truncate_item(trans, root, path,
 574                                                             new_size, 1);
 575                                 }
 576                         }
 577                 }
 578                 /* delete the entire extent */
 579                 if (!keep) {
 580                         if (found_inline)
 581                                 inode_sub_bytes(inode, extent_end -
 582                                                 key.offset);
 583                         ret = btrfs_del_item(trans, root, path);
 584                         /* TODO update progress marker and return */
 585                         BUG_ON(ret);
 586                         extent = NULL;
 587                         btrfs_release_path(root, path);
 588                         /* the extent will be freed later */
 589                 }
 590                 if (bookend && found_inline && start <= key.offset) {
 591                         u32 new_size;
 592                         new_size = btrfs_file_extent_calc_inline_size(
 593                                                    extent_end - end);
 594                         inode_sub_bytes(inode, end - key.offset);
 595                         btrfs_set_file_extent_ram_bytes(leaf, extent,
 596                                                         new_size);
 597                         if (!compression && !encryption)
 598                                 ret = btrfs_truncate_item(trans, root, path,
 599                                                           new_size, 0);
 600                         BUG_ON(ret);
 601                 }
 602                 /* create bookend, splitting the extent in two */
 603                 if (bookend && found_extent) {
 604                         struct btrfs_key ins;
 605                         ins.objectid = inode->i_ino;
 606                         ins.offset = end;
 607                         btrfs_set_key_type(&ins, BTRFS_EXTENT_DATA_KEY);
 608
 609                         btrfs_release_path(root, path);
 610                         path->leave_spinning = 1;
 611                         ret = btrfs_insert_empty_item(trans, root, path, &ins,
 612                                                       sizeof(*extent));
 613                         BUG_ON(ret);
 614
 615                         leaf = path->nodes[0];
 616                         extent = btrfs_item_ptr(leaf, path->slots[0],
 617                                                 struct btrfs_file_extent_item);
 618                         write_extent_buffer(leaf, &old,
 619                                             (unsigned long)extent, sizeof(old));
 620
 621                         btrfs_set_file_extent_compression(leaf, extent,
 622                                                           compression);
 623                         btrfs_set_file_extent_encryption(leaf, extent,
 624                                                          encryption);
 625                         btrfs_set_file_extent_other_encoding(leaf, extent,
 626                                                              other_encoding);
 627                         btrfs_set_file_extent_offset(leaf, extent,
 628                                     le64_to_cpu(old.offset) + end - key.offset);
 629                         WARN_ON(le64_to_cpu(old.num_bytes) <
 630                                 (extent_end - end));
 631                         btrfs_set_file_extent_num_bytes(leaf, extent,
 632                                                         extent_end - end);
 633
 634                         /*
 635                          * set the ram bytes to the size of the full extent
 636                          * before splitting.  This is a worst case flag,
 637                          * but its the best we can do because we don't know
 638                          * how splitting affects compression
 639                          */
 640                         btrfs_set_file_extent_ram_bytes(leaf, extent,
 641                                                         ram_bytes);
 642                         btrfs_set_file_extent_type(leaf, extent, found_type);
 643
 644                         btrfs_unlock_up_safe(path, 1);
 645                         btrfs_mark_buffer_dirty(path->nodes[0]);
 646                         btrfs_set_lock_blocking(path->nodes[0]);
 647
 648                         if (disk_bytenr != 0) {
 649                                 ret = btrfs_update_extent_ref(trans, root,
 650                                                 disk_bytenr,
 651                                                 le64_to_cpu(old.disk_num_bytes),
 652                                                 orig_parent,
 653                                                 leaf->start,
 654                                                 root->root_key.objectid,
 655                                                 trans->transid, ins.objectid);
 656
 657                                 BUG_ON(ret);
 658                         }
 659                         path->leave_spinning = 0;
 660                         btrfs_release_path(root, path);
 661                         if (disk_bytenr != 0)
 662                                 inode_add_bytes(inode, extent_end - end);
 663                 }
 664
 665                 if (found_extent && !keep) {
 666                         u64 old_disk_bytenr = le64_to_cpu(old.disk_bytenr);
 667
 668                         if (old_disk_bytenr != 0) {
 669                                 inode_sub_bytes(inode,
 670                                                 le64_to_cpu(old.num_bytes));
 671                                 ret = btrfs_free_extent(trans, root,
 672                                                 old_disk_bytenr,
 673                                                 le64_to_cpu(old.disk_num_bytes),
 674                                                 leaf_start, root_owner,
 675                                                 root_gen, key.objectid, 0);
 676                                 BUG_ON(ret);
 677                                 *hint_byte = old_disk_bytenr;
 678                         }
 679                 }
 680
 681                 if (search_start >= end) {
 682                         ret = 0;
 683                         goto out;
 684                 }
 685         }
 686 out:
 687         btrfs_free_path(path);
 688         if (locked_end > orig_locked_end) {
 689                 unlock_extent(&BTRFS_I(inode)->io_tree, orig_locked_end,
 690                               locked_end - 1, GFP_NOFS);
 691         }
 692         btrfs_check_file(root, inode);
 693         return ret;
 694 }
 695
 696 static int extent_mergeable(struct extent_buffer *leaf, int slot,
 697                             u64 objectid, u64 bytenr, u64 *start, u64 *end)
 698 {
 699         struct btrfs_file_extent_item *fi;
 700         struct btrfs_key key;
 701         u64 extent_end;
 702
 703         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
 704                 return 0;
 705
 706         btrfs_item_key_to_cpu(leaf, &key, slot);
 707         if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
 708                 return 0;
 709
 710         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
 711         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
 712             btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
 713             btrfs_file_extent_compression(leaf, fi) ||
 714             btrfs_file_extent_encryption(leaf, fi) ||
 715             btrfs_file_extent_other_encoding(leaf, fi))
 716                 return 0;
 717
 718         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 719         if ((*start && *start != key.offset) || (*end && *end != extent_end))
 720                 return 0;
 721
 722         *start = key.offset;
 723         *end = extent_end;
 724         return 1;
 725 }
 726
 727 /*
 728  * Mark extent in the range start - end as written.
 729  *
 730  * This changes extent type from 'pre-allocated' to 'regular'. If only
 731  * part of extent is marked as written, the extent will be split into
 732  * two or three.
 733  */
 734 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
 735                               struct btrfs_root *root,
 736                               struct inode *inode, u64 start, u64 end)
 737 {
 738         struct extent_buffer *leaf;
 739         struct btrfs_path *path;
 740         struct btrfs_file_extent_item *fi;
 741         struct btrfs_key key;
 742         u64 bytenr;
 743         u64 num_bytes;
 744         u64 extent_end;
 745         u64 extent_offset;
 746         u64 other_start;
 747         u64 other_end;
 748         u64 split = start;
 749         u64 locked_end = end;
 750         u64 orig_parent;
 751         int extent_type;
 752         int split_end = 1;
 753         int ret;
 754
 755         btrfs_drop_extent_cache(inode, start, end - 1, 0);
 756
 757         path = btrfs_alloc_path();
 758         BUG_ON(!path);
 759 again:
 760         key.objectid = inode->i_ino;
 761         key.type = BTRFS_EXTENT_DATA_KEY;
 762         if (split == start)
 763                 key.offset = split;
 764         else
 765                 key.offset = split - 1;
 766
 767         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 768         if (ret > 0 && path->slots[0] > 0)
 769                 path->slots[0]--;
 770
 771         leaf = path->nodes[0];
 772         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 773         BUG_ON(key.objectid != inode->i_ino ||
 774                key.type != BTRFS_EXTENT_DATA_KEY);
 775         fi = btrfs_item_ptr(leaf, path->slots[0],
 776                             struct btrfs_file_extent_item);
 777         extent_type = btrfs_file_extent_type(leaf, fi);
 778         BUG_ON(extent_type != BTRFS_FILE_EXTENT_PREALLOC);
 779         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 780         BUG_ON(key.offset > start || extent_end < end);
 781
 782         bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 783         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
 784         extent_offset = btrfs_file_extent_offset(leaf, fi);
 785
 786         if (key.offset == start)
 787                 split = end;
 788
 789         if (key.offset == start && extent_end == end) {
 790                 int del_nr = 0;
 791                 int del_slot = 0;
 792                 u64 leaf_owner = btrfs_header_owner(leaf);
 793                 u64 leaf_gen = btrfs_header_generation(leaf);
 794                 other_start = end;
 795                 other_end = 0;
 796                 if (extent_mergeable(leaf, path->slots[0] + 1, inode->i_ino,
 797                                      bytenr, &other_start, &other_end)) {
 798                         extent_end = other_end;
 799                         del_slot = path->slots[0] + 1;
 800                         del_nr++;
 801                         ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
 802                                                 leaf->start, leaf_owner,
 803                                                 leaf_gen, inode->i_ino, 0);
 804                         BUG_ON(ret);
 805                 }
 806                 other_start = 0;
 807                 other_end = start;
 808                 if (extent_mergeable(leaf, path->slots[0] - 1, inode->i_ino,
 809                                      bytenr, &other_start, &other_end)) {
 810                         key.offset = other_start;
 811                         del_slot = path->slots[0];
 812                         del_nr++;
 813                         ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
 814                                                 leaf->start, leaf_owner,
 815                                                 leaf_gen, inode->i_ino, 0);
 816                         BUG_ON(ret);
 817                 }
 818                 split_end = 0;
 819                 if (del_nr == 0) {
 820                         btrfs_set_file_extent_type(leaf, fi,
 821                                                    BTRFS_FILE_EXTENT_REG);
 822                         goto done;
 823                 }
 824
 825                 fi = btrfs_item_ptr(leaf, del_slot - 1,
 826                                     struct btrfs_file_extent_item);
 827                 btrfs_set_file_extent_type(leaf, fi, BTRFS_FILE_EXTENT_REG);
 828                 btrfs_set_file_extent_num_bytes(leaf, fi,
 829                                                 extent_end - key.offset);
 830                 btrfs_mark_buffer_dirty(leaf);
 831
 832                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
 833                 BUG_ON(ret);
 834                 goto release;
 835         } else if (split == start) {
 836                 if (locked_end < extent_end) {
 837                         ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
 838                                         locked_end, extent_end - 1, GFP_NOFS);
 839                         if (!ret) {
 840                                 btrfs_release_path(root, path);
 841                                 lock_extent(&BTRFS_I(inode)->io_tree,
 842                                         locked_end, extent_end - 1, GFP_NOFS);
 843                                 locked_end = extent_end;
 844                                 goto again;
 845                         }
 846                         locked_end = extent_end;
 847                 }
 848                 btrfs_set_file_extent_num_bytes(leaf, fi, split - key.offset);
 849                 extent_offset += split - key.offset;
 850         } else  {
 851                 BUG_ON(key.offset != start);
 852                 btrfs_set_file_extent_offset(leaf, fi, extent_offset +
 853                                              split - key.offset);
 854                 btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - split);
 855                 key.offset = split;
 856                 btrfs_set_item_key_safe(trans, root, path, &key);
 857                 extent_end = split;
 858         }
 859
 860         if (extent_end == end) {
 861                 split_end = 0;
 862                 extent_type = BTRFS_FILE_EXTENT_REG;
 863         }
 864         if (extent_end == end && split == start) {
 865                 other_start = end;
 866                 other_end = 0;
 867                 if (extent_mergeable(leaf, path->slots[0] + 1, inode->i_ino,
 868                                      bytenr, &other_start, &other_end)) {
 869                         path->slots[0]++;
 870                         fi = btrfs_item_ptr(leaf, path->slots[0],
 871                                             struct btrfs_file_extent_item);
 872                         key.offset = split;
 873                         btrfs_set_item_key_safe(trans, root, path, &key);
 874                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
 875                         btrfs_set_file_extent_num_bytes(leaf, fi,
 876                                                         other_end - split);
 877                         goto done;
 878                 }
 879         }
 880         if (extent_end == end && split == end) {
 881                 other_start = 0;
 882                 other_end = start;
 883                 if (extent_mergeable(leaf, path->slots[0] - 1 , inode->i_ino,
 884                                      bytenr, &other_start, &other_end)) {
 885                         path->slots[0]--;
 886                         fi = btrfs_item_ptr(leaf, path->slots[0],
 887                                             struct btrfs_file_extent_item);
 888                         btrfs_set_file_extent_num_bytes(leaf, fi, extent_end -
 889                                                         other_start);
 890                         goto done;
 891                 }
 892         }
 893
 894         btrfs_mark_buffer_dirty(leaf);
 895
 896         orig_parent = leaf->start;
 897         ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes,
 898                                    orig_parent, root->root_key.objectid,
 899                                    trans->transid, inode->i_ino);
 900         BUG_ON(ret);
 901         btrfs_release_path(root, path);
 902
 903         key.offset = start;
 904         ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*fi));
 905         BUG_ON(ret);
 906
 907         leaf = path->nodes[0];
 908         fi = btrfs_item_ptr(leaf, path->slots[0],
 909                             struct btrfs_file_extent_item);
 910         btrfs_set_file_extent_generation(leaf, fi, trans->transid);
 911         btrfs_set_file_extent_type(leaf, fi, extent_type);
 912         btrfs_set_file_extent_disk_bytenr(leaf, fi, bytenr);
 913         btrfs_set_file_extent_disk_num_bytes(leaf, fi, num_bytes);
 914         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
 915         btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - key.offset);
 916         btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
 917         btrfs_set_file_extent_compression(leaf, fi, 0);
 918         btrfs_set_file_extent_encryption(leaf, fi, 0);
 919         btrfs_set_file_extent_other_encoding(leaf, fi, 0);
 920
 921         if (orig_parent != leaf->start) {
 922                 ret = btrfs_update_extent_ref(trans, root, bytenr, num_bytes,
 923                                               orig_parent, leaf->start,
 924                                               root->root_key.objectid,
 925                                               trans->transid, inode->i_ino);
 926                 BUG_ON(ret);
 927         }
 928 done:
 929         btrfs_mark_buffer_dirty(leaf);
 930
 931 release:
 932         btrfs_release_path(root, path);
 933         if (split_end && split == start) {
 934                 split = end;
 935                 goto again;
 936         }
 937         if (locked_end > end) {
 938                 unlock_extent(&BTRFS_I(inode)->io_tree, end, locked_end - 1,
 939                               GFP_NOFS);
 940         }
 941         btrfs_free_path(path);
 942         return 0;
 943 }
 944
 945 /*
 946  * this gets pages into the page cache and locks them down, it also properly
 947  * waits for data=ordered extents to finish before allowing the pages to be
 948  * modified.
 949  */
 950 static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
 951                          struct page **pages, size_t num_pages,
 952                          loff_t pos, unsigned long first_index,
 953                          unsigned long last_index, size_t write_bytes)
 954 {
 955         int i;
 956         unsigned long index = pos >> PAGE_CACHE_SHIFT;
 957         struct inode *inode = fdentry(file)->d_inode;
 958         int err = 0;
 959         u64 start_pos;
 960         u64 last_pos;
 961
 962         start_pos = pos & ~((u64)root->sectorsize - 1);
 963         last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
 964
 965         if (start_pos > inode->i_size) {
 966                 err = btrfs_cont_expand(inode, start_pos);
 967                 if (err)
 968                         return err;
 969         }
 970
 971         memset(pages, 0, num_pages * sizeof(struct page *));
 972 again:
 973         for (i = 0; i < num_pages; i++) {
 974                 pages[i] = grab_cache_page(inode->i_mapping, index + i);
 975                 if (!pages[i]) {
 976                         err = -ENOMEM;
 977                         BUG_ON(1);
 978                 }
 979                 wait_on_page_writeback(pages[i]);
 980         }
 981         if (start_pos < inode->i_size) {
 982                 struct btrfs_ordered_extent *ordered;
 983                 lock_extent(&BTRFS_I(inode)->io_tree,
 984                             start_pos, last_pos - 1, GFP_NOFS);
 985                 ordered = btrfs_lookup_first_ordered_extent(inode,
 986                                                             last_pos - 1);
 987                 if (ordered &&
 988                     ordered->file_offset + ordered->len > start_pos &&
 989                     ordered->file_offset < last_pos) {
 990                         btrfs_put_ordered_extent(ordered);
 991                         unlock_extent(&BTRFS_I(inode)->io_tree,
 992                                       start_pos, last_pos - 1, GFP_NOFS);
 993                         for (i = 0; i < num_pages; i++) {
 994                                 unlock_page(pages[i]);
 995                                 page_cache_release(pages[i]);
 996                         }
 997                         btrfs_wait_ordered_range(inode, start_pos,
 998                                                  last_pos - start_pos);
 999                         goto again;
1000                 }
1001                 if (ordered)
1002                         btrfs_put_ordered_extent(ordered);
1003
1004                 clear_extent_bits(&BTRFS_I(inode)->io_tree, start_pos,
1005                                   last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC,
1006                                   GFP_NOFS);
1007                 unlock_extent(&BTRFS_I(inode)->io_tree,
1008                               start_pos, last_pos - 1, GFP_NOFS);
1009         }
1010         for (i = 0; i < num_pages; i++) {
1011                 clear_page_dirty_for_io(pages[i]);
1012                 set_page_extent_mapped(pages[i]);
1013                 WARN_ON(!PageLocked(pages[i]));
1014         }
1015         return 0;
1016 }
1017
1018 static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
1019                                 size_t count, loff_t *ppos)
1020 {
1021         loff_t pos;
1022         loff_t start_pos;
1023         ssize_t num_written = 0;
1024         ssize_t err = 0;
1025         int ret = 0;
1026         struct inode *inode = fdentry(file)->d_inode;
1027         struct btrfs_root *root = BTRFS_I(inode)->root;
1028         struct page **pages = NULL;
1029         int nrptrs;
1030         struct page *pinned[2];
1031         unsigned long first_index;
1032         unsigned long last_index;
1033         int will_write;
1034
1035         will_write = ((file->f_flags & O_SYNC) || IS_SYNC(inode) ||
1036                       (file->f_flags & O_DIRECT));
1037
1038         nrptrs = min((count + PAGE_CACHE_SIZE - 1) / PAGE_CACHE_SIZE,
1039                      PAGE_CACHE_SIZE / (sizeof(struct page *)));
1040         pinned[0] = NULL;
1041         pinned[1] = NULL;
1042
1043         pos = *ppos;
1044         start_pos = pos;
1045
1046         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
1047         current->backing_dev_info = inode->i_mapping->backing_dev_info;
1048         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
1049         if (err)
1050                 goto out_nolock;
1051         if (count == 0)
1052                 goto out_nolock;
1053
1054         err = file_remove_suid(file);
1055         if (err)
1056                 goto out_nolock;
1057         file_update_time(file);
1058
1059         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
1060
1061         mutex_lock(&inode->i_mutex);
1062         BTRFS_I(inode)->sequence++;
1063         first_index = pos >> PAGE_CACHE_SHIFT;
1064         last_index = (pos + count) >> PAGE_CACHE_SHIFT;
1065
1066         /*
1067          * there are lots of better ways to do this, but this code
1068          * makes sure the first and last page in the file range are
1069          * up to date and ready for cow
1070          */
1071         if ((pos & (PAGE_CACHE_SIZE - 1))) {
1072                 pinned[0] = grab_cache_page(inode->i_mapping, first_index);
1073                 if (!PageUptodate(pinned[0])) {
1074                         ret = btrfs_readpage(NULL, pinned[0]);
1075                         BUG_ON(ret);
1076                         wait_on_page_locked(pinned[0]);
1077                 } else {
1078                         unlock_page(pinned[0]);
1079                 }
1080         }
1081         if ((pos + count) & (PAGE_CACHE_SIZE - 1)) {
1082                 pinned[1] = grab_cache_page(inode->i_mapping, last_index);
1083                 if (!PageUptodate(pinned[1])) {
1084                         ret = btrfs_readpage(NULL, pinned[1]);
1085                         BUG_ON(ret);
1086                         wait_on_page_locked(pinned[1]);
1087                 } else {
1088                         unlock_page(pinned[1]);
1089                 }
1090         }
1091
1092         while (count > 0) {
1093                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
1094                 size_t write_bytes = min(count, nrptrs *
1095                                         (size_t)PAGE_CACHE_SIZE -
1096                                          offset);
1097                 size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
1098                                         PAGE_CACHE_SHIFT;
1099
1100                 WARN_ON(num_pages > nrptrs);
1101                 memset(pages, 0, sizeof(struct page *) * nrptrs);
1102
1103                 ret = btrfs_check_data_free_space(root, inode, write_bytes);
1104                 if (ret)
1105                         goto out;
1106
1107                 ret = prepare_pages(root, file, pages, num_pages,
1108                                     pos, first_index, last_index,
1109                                     write_bytes);
1110                 if (ret) {
1111                         btrfs_free_reserved_data_space(root, inode,
1112                                                        write_bytes);
1113                         goto out;
1114                 }
1115
1116                 ret = btrfs_copy_from_user(pos, num_pages,
1117                                            write_bytes, pages, buf);
1118                 if (ret) {
1119                         btrfs_free_reserved_data_space(root, inode,
1120                                                        write_bytes);
1121                         btrfs_drop_pages(pages, num_pages);
1122                         goto out;
1123                 }
1124
1125                 ret = dirty_and_release_pages(NULL, root, file, pages,
1126                                               num_pages, pos, write_bytes);
1127                 btrfs_drop_pages(pages, num_pages);
1128                 if (ret) {
1129                         btrfs_free_reserved_data_space(root, inode,
1130                                                        write_bytes);
1131                         goto out;
1132                 }
1133
1134                 if (will_write) {
1135                         btrfs_fdatawrite_range(inode->i_mapping, pos,
1136                                                pos + write_bytes - 1,
1137                                                WB_SYNC_ALL);
1138                 } else {
1139                         balance_dirty_pages_ratelimited_nr(inode->i_mapping,
1140                                                            num_pages);
1141                         if (num_pages <
1142                             (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
1143                                 btrfs_btree_balance_dirty(root, 1);
1144                         btrfs_throttle(root);
1145                 }
1146
1147                 buf += write_bytes;
1148                 count -= write_bytes;
1149                 pos += write_bytes;
1150                 num_written += write_bytes;
1151
1152                 cond_resched();
1153         }
1154 out:
1155         mutex_unlock(&inode->i_mutex);
1156         if (ret)
1157                 err = ret;
1158
1159 out_nolock:
1160         kfree(pages);
1161         if (pinned[0])
1162                 page_cache_release(pinned[0]);
1163         if (pinned[1])
1164                 page_cache_release(pinned[1]);
1165         *ppos = pos;
1166
1167         /*
1168          * we want to make sure fsync finds this change
1169          * but we haven't joined a transaction running right now.
1170          *
1171          * Later on, someone is sure to update the inode and get the
1172          * real transid recorded.
1173          *
1174          * We set last_trans now to the fs_info generation + 1,
1175          * this will either be one more than the running transaction
1176          * or the generation used for the next transaction if there isn't
1177          * one running right now.
1178          */
1179         BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
1180
1181         if (num_written > 0 && will_write) {
1182                 struct btrfs_trans_handle *trans;
1183
1184                 err = btrfs_wait_ordered_range(inode, start_pos, num_written);
1185                 if (err)
1186                         num_written = err;
1187
1188                 if ((file->f_flags & O_SYNC) || IS_SYNC(inode)) {
1189                         trans = btrfs_start_transaction(root, 1);
1190                         ret = btrfs_log_dentry_safe(trans, root,
1191                                                     file->f_dentry);
1192                         if (ret == 0) {
1193                                 ret = btrfs_sync_log(trans, root);
1194                                 if (ret == 0)
1195                                         btrfs_end_transaction(trans, root);
1196                                 else
1197                                         btrfs_commit_transaction(trans, root);
1198                         } else {
1199                                 btrfs_commit_transaction(trans, root);
1200                         }
1201                 }
1202                 if (file->f_flags & O_DIRECT) {
1203                         invalidate_mapping_pages(inode->i_mapping,
1204                               start_pos >> PAGE_CACHE_SHIFT,
1205                              (start_pos + num_written - 1) >> PAGE_CACHE_SHIFT);
1206                 }
1207         }
1208         current->backing_dev_info = NULL;
1209         return num_written ? num_written : err;
1210 }
1211
1212 int btrfs_release_file(struct inode *inode, struct file *filp)
1213 {
1214         /*
1215          * ordered_data_close is set by settattr when we are about to truncate
1216          * a file from a non-zero size to a zero size.  This tries to
1217          * flush down new bytes that may have been written if the
1218          * application were using truncate to replace a file in place.
1219          */
1220         if (BTRFS_I(inode)->ordered_data_close) {
1221                 BTRFS_I(inode)->ordered_data_close = 0;
1222                 btrfs_add_ordered_operation(NULL, BTRFS_I(inode)->root, inode);
1223                 if (inode->i_size > BTRFS_ORDERED_OPERATIONS_FLUSH_LIMIT)
1224                         filemap_flush(inode->i_mapping);
1225         }
1226         if (filp->private_data)
1227                 btrfs_ioctl_trans_end(filp);
1228         return 0;
1229 }
1230
1231 /*
1232  * fsync call for both files and directories.  This logs the inode into
1233  * the tree log instead of forcing full commits whenever possible.
1234  *
1235  * It needs to call filemap_fdatawait so that all ordered extent updates are
1236  * in the metadata btree are up to date for copying to the log.
1237  *
1238  * It drops the inode mutex before doing the tree log commit.  This is an
1239  * important optimization for directories because holding the mutex prevents
1240  * new operations on the dir while we write to disk.
1241  */
1242 int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
1243 {
1244         struct inode *inode = dentry->d_inode;
1245         struct btrfs_root *root = BTRFS_I(inode)->root;
1246         int ret = 0;
1247         struct btrfs_trans_handle *trans;
1248
1249         /*
1250          * check the transaction that last modified this inode
1251          * and see if its already been committed
1252          */
1253         if (!BTRFS_I(inode)->last_trans)
1254                 goto out;
1255
1256         mutex_lock(&root->fs_info->trans_mutex);
1257         if (BTRFS_I(inode)->last_trans <=
1258             root->fs_info->last_trans_committed) {
1259                 BTRFS_I(inode)->last_trans = 0;
1260                 mutex_unlock(&root->fs_info->trans_mutex);
1261                 goto out;
1262         }
1263         mutex_unlock(&root->fs_info->trans_mutex);
1264
1265         root->log_batch++;
1266         filemap_fdatawrite(inode->i_mapping);
1267         btrfs_wait_ordered_range(inode, 0, (u64)-1);
1268         root->log_batch++;
1269
1270         /*
1271          * ok we haven't committed the transaction yet, lets do a commit
1272          */
1273         if (file && file->private_data)
1274                 btrfs_ioctl_trans_end(file);
1275
1276         trans = btrfs_start_transaction(root, 1);
1277         if (!trans) {
1278                 ret = -ENOMEM;
1279                 goto out;
1280         }
1281
1282         ret = btrfs_log_dentry_safe(trans, root, dentry);
1283         if (ret < 0)
1284                 goto out;
1285
1286         /* we've logged all the items and now have a consistent
1287          * version of the file in the log.  It is possible that
1288          * someone will come in and modify the file, but that's
1289          * fine because the log is consistent on disk, and we
1290          * have references to all of the file's extents
1291          *
1292          * It is possible that someone will come in and log the
1293          * file again, but that will end up using the synchronization
1294          * inside btrfs_sync_log to keep things safe.
1295          */
1296         mutex_unlock(&dentry->d_inode->i_mutex);
1297
1298         if (ret > 0) {
1299                 ret = btrfs_commit_transaction(trans, root);
1300         } else {
1301                 ret = btrfs_sync_log(trans, root);
1302                 if (ret == 0)
1303                         ret = btrfs_end_transaction(trans, root);
1304                 else
1305                         ret = btrfs_commit_transaction(trans, root);
1306         }
1307         mutex_lock(&dentry->d_inode->i_mutex);
1308 out:
1309         return ret > 0 ? EIO : ret;
1310 }
1311
1312 static struct vm_operations_struct btrfs_file_vm_ops = {
1313         .fault          = filemap_fault,
1314         .page_mkwrite   = btrfs_page_mkwrite,
1315 };
1316
1317 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
1318 {
1319         vma->vm_ops = &btrfs_file_vm_ops;
1320         file_accessed(filp);
1321         return 0;
1322 }
1323
1324 struct file_operations btrfs_file_operations = {
1325         .llseek         = generic_file_llseek,
1326         .read           = do_sync_read,
1327         .aio_read       = generic_file_aio_read,
1328         .splice_read    = generic_file_splice_read,
1329         .write          = btrfs_file_write,
1330         .mmap           = btrfs_file_mmap,
1331         .open           = generic_file_open,
1332         .release        = btrfs_release_file,
1333         .fsync          = btrfs_sync_file,
1334         .unlocked_ioctl = btrfs_ioctl,
1335 #ifdef CONFIG_COMPAT
1336         .compat_ioctl   = btrfs_ioctl,
1337 #endif
1338 };