fs/btrfs/file.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/fs.h>
  20 #include <linux/pagemap.h>
  21 #include <linux/highmem.h>
  22 #include <linux/time.h>
  23 #include <linux/init.h>
  24 #include <linux/string.h>
  25 #include <linux/backing-dev.h>
  26 #include <linux/mpage.h>
  27 #include <linux/falloc.h>
  28 #include <linux/swap.h>
  29 #include <linux/writeback.h>
  30 #include <linux/statfs.h>
  31 #include <linux/compat.h>
  32 #include <linux/slab.h>
  33 #include "ctree.h"
  34 #include "disk-io.h"
  35 #include "transaction.h"
  36 #include "btrfs_inode.h"
  37 #include "ioctl.h"
  38 #include "print-tree.h"
  39 #include "tree-log.h"
  40 #include "locking.h"
  41 #include "compat.h"
  42
  43 /*
  44  * when auto defrag is enabled we
  45  * queue up these defrag structs to remember which
  46  * inodes need defragging passes
  47  */
  48 struct inode_defrag {
  49         struct rb_node rb_node;
  50         /* objectid */
  51         u64 ino;
  52         /*
  53          * transid where the defrag was added, we search for
  54          * extents newer than this
  55          */
  56         u64 transid;
  57
  58         /* root objectid */
  59         u64 root;
  60
  61         /* last offset we were able to defrag */
  62         u64 last_offset;
  63
  64         /* if we've wrapped around back to zero once already */
  65         int cycled;
  66 };
  67
  68 /* pop a record for an inode into the defrag tree.  The lock
  69  * must be held already
  70  *
  71  * If you're inserting a record for an older transid than an
  72  * existing record, the transid already in the tree is lowered
  73  *
  74  * If an existing record is found the defrag item you
  75  * pass in is freed
  76  */
  77 static void __btrfs_add_inode_defrag(struct inode *inode,
  78                                     struct inode_defrag *defrag)
  79 {
  80         struct btrfs_root *root = BTRFS_I(inode)->root;
  81         struct inode_defrag *entry;
  82         struct rb_node **p;
  83         struct rb_node *parent = NULL;
  84
  85         p = &root->fs_info->defrag_inodes.rb_node;
  86         while (*p) {
  87                 parent = *p;
  88                 entry = rb_entry(parent, struct inode_defrag, rb_node);
  89
  90                 if (defrag->ino < entry->ino)
  91                         p = &parent->rb_left;
  92                 else if (defrag->ino > entry->ino)
  93                         p = &parent->rb_right;
  94                 else {
  95                         /* if we're reinserting an entry for
  96                          * an old defrag run, make sure to
  97                          * lower the transid of our existing record
  98                          */
  99                         if (defrag->transid < entry->transid)
 100                                 entry->transid = defrag->transid;
 101                         if (defrag->last_offset > entry->last_offset)
 102                                 entry->last_offset = defrag->last_offset;
 103                         goto exists;
 104                 }
 105         }
 106         BTRFS_I(inode)->in_defrag = 1;
 107         rb_link_node(&defrag->rb_node, parent, p);
 108         rb_insert_color(&defrag->rb_node, &root->fs_info->defrag_inodes);
 109         return;
 110
 111 exists:
 112         kfree(defrag);
 113         return;
 114
 115 }
 116
 117 /*
 118  * insert a defrag record for this inode if auto defrag is
 119  * enabled
 120  */
 121 int btrfs_add_inode_defrag(struct btrfs_trans_handle *trans,
 122                            struct inode *inode)
 123 {
 124         struct btrfs_root *root = BTRFS_I(inode)->root;
 125         struct inode_defrag *defrag;
 126         u64 transid;
 127
 128         if (!btrfs_test_opt(root, AUTO_DEFRAG))
 129                 return 0;
 130
 131         if (btrfs_fs_closing(root->fs_info))
 132                 return 0;
 133
 134         if (BTRFS_I(inode)->in_defrag)
 135                 return 0;
 136
 137         if (trans)
 138                 transid = trans->transid;
 139         else
 140                 transid = BTRFS_I(inode)->root->last_trans;
 141
 142         defrag = kzalloc(sizeof(*defrag), GFP_NOFS);
 143         if (!defrag)
 144                 return -ENOMEM;
 145
 146         defrag->ino = btrfs_ino(inode);
 147         defrag->transid = transid;
 148         defrag->root = root->root_key.objectid;
 149
 150         spin_lock(&root->fs_info->defrag_inodes_lock);
 151         if (!BTRFS_I(inode)->in_defrag)
 152                 __btrfs_add_inode_defrag(inode, defrag);
 153         else
 154                 kfree(defrag);
 155         spin_unlock(&root->fs_info->defrag_inodes_lock);
 156         return 0;
 157 }
 158
 159 /*
 160  * must be called with the defrag_inodes lock held
 161  */
 162 struct inode_defrag *btrfs_find_defrag_inode(struct btrfs_fs_info *info, u64 ino,
 163                                              struct rb_node **next)
 164 {
 165         struct inode_defrag *entry = NULL;
 166         struct rb_node *p;
 167         struct rb_node *parent = NULL;
 168
 169         p = info->defrag_inodes.rb_node;
 170         while (p) {
 171                 parent = p;
 172                 entry = rb_entry(parent, struct inode_defrag, rb_node);
 173
 174                 if (ino < entry->ino)
 175                         p = parent->rb_left;
 176                 else if (ino > entry->ino)
 177                         p = parent->rb_right;
 178                 else
 179                         return entry;
 180         }
 181
 182         if (next) {
 183                 while (parent && ino > entry->ino) {
 184                         parent = rb_next(parent);
 185                         entry = rb_entry(parent, struct inode_defrag, rb_node);
 186                 }
 187                 *next = parent;
 188         }
 189         return NULL;
 190 }
 191
 192 /*
 193  * run through the list of inodes in the FS that need
 194  * defragging
 195  */
 196 int btrfs_run_defrag_inodes(struct btrfs_fs_info *fs_info)
 197 {
 198         struct inode_defrag *defrag;
 199         struct btrfs_root *inode_root;
 200         struct inode *inode;
 201         struct rb_node *n;
 202         struct btrfs_key key;
 203         struct btrfs_ioctl_defrag_range_args range;
 204         u64 first_ino = 0;
 205         int num_defrag;
 206         int defrag_batch = 1024;
 207
 208         memset(&range, 0, sizeof(range));
 209         range.len = (u64)-1;
 210
 211         atomic_inc(&fs_info->defrag_running);
 212         spin_lock(&fs_info->defrag_inodes_lock);
 213         while(1) {
 214                 n = NULL;
 215
 216                 /* find an inode to defrag */
 217                 defrag = btrfs_find_defrag_inode(fs_info, first_ino, &n);
 218                 if (!defrag) {
 219                         if (n)
 220                                 defrag = rb_entry(n, struct inode_defrag, rb_node);
 221                         else if (first_ino) {
 222                                 first_ino = 0;
 223                                 continue;
 224                         } else {
 225                                 break;
 226                         }
 227                 }
 228
 229                 /* remove it from the rbtree */
 230                 first_ino = defrag->ino + 1;
 231                 rb_erase(&defrag->rb_node, &fs_info->defrag_inodes);
 232
 233                 if (btrfs_fs_closing(fs_info))
 234                         goto next_free;
 235
 236                 spin_unlock(&fs_info->defrag_inodes_lock);
 237
 238                 /* get the inode */
 239                 key.objectid = defrag->root;
 240                 btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
 241                 key.offset = (u64)-1;
 242                 inode_root = btrfs_read_fs_root_no_name(fs_info, &key);
 243                 if (IS_ERR(inode_root))
 244                         goto next;
 245
 246                 key.objectid = defrag->ino;
 247                 btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
 248                 key.offset = 0;
 249
 250                 inode = btrfs_iget(fs_info->sb, &key, inode_root, NULL);
 251                 if (IS_ERR(inode))
 252                         goto next;
 253
 254                 /* do a chunk of defrag */
 255                 BTRFS_I(inode)->in_defrag = 0;
 256                 range.start = defrag->last_offset;
 257                 num_defrag = btrfs_defrag_file(inode, NULL, &range, defrag->transid,
 258                                                defrag_batch);
 259                 /*
 260                  * if we filled the whole defrag batch, there
 261                  * must be more work to do.  Queue this defrag
 262                  * again
 263                  */
 264                 if (num_defrag == defrag_batch) {
 265                         defrag->last_offset = range.start;
 266                         __btrfs_add_inode_defrag(inode, defrag);
 267                         /*
 268                          * we don't want to kfree defrag, we added it back to
 269                          * the rbtree
 270                          */
 271                         defrag = NULL;
 272                 } else if (defrag->last_offset && !defrag->cycled) {
 273                         /*
 274                          * we didn't fill our defrag batch, but
 275                          * we didn't start at zero.  Make sure we loop
 276                          * around to the start of the file.
 277                          */
 278                         defrag->last_offset = 0;
 279                         defrag->cycled = 1;
 280                         __btrfs_add_inode_defrag(inode, defrag);
 281                         defrag = NULL;
 282                 }
 283
 284                 iput(inode);
 285 next:
 286                 spin_lock(&fs_info->defrag_inodes_lock);
 287 next_free:
 288                 kfree(defrag);
 289         }
 290         spin_unlock(&fs_info->defrag_inodes_lock);
 291
 292         atomic_dec(&fs_info->defrag_running);
 293
 294         /*
 295          * during unmount, we use the transaction_wait queue to
 296          * wait for the defragger to stop
 297          */
 298         wake_up(&fs_info->transaction_wait);
 299         return 0;
 300 }
 301
 302 /* simple helper to fault in pages and copy.  This should go away
 303  * and be replaced with calls into generic code.
 304  */
 305 static noinline int btrfs_copy_from_user(loff_t pos, int num_pages,
 306                                          size_t write_bytes,
 307                                          struct page **prepared_pages,
 308                                          struct iov_iter *i)
 309 {
 310         size_t copied = 0;
 311         size_t total_copied = 0;
 312         int pg = 0;
 313         int offset = pos & (PAGE_CACHE_SIZE - 1);
 314
 315         while (write_bytes > 0) {
 316                 size_t count = min_t(size_t,
 317                                      PAGE_CACHE_SIZE - offset, write_bytes);
 318                 struct page *page = prepared_pages[pg];
 319                 /*
 320                  * Copy data from userspace to the current page
 321                  *
 322                  * Disable pagefault to avoid recursive lock since
 323                  * the pages are already locked
 324                  */
 325                 pagefault_disable();
 326                 copied = iov_iter_copy_from_user_atomic(page, i, offset, count);
 327                 pagefault_enable();
 328
 329                 /* Flush processor's dcache for this page */
 330                 flush_dcache_page(page);
 331
 332                 /*
 333                  * if we get a partial write, we can end up with
 334                  * partially up to date pages.  These add
 335                  * a lot of complexity, so make sure they don't
 336                  * happen by forcing this copy to be retried.
 337                  *
 338                  * The rest of the btrfs_file_write code will fall
 339                  * back to page at a time copies after we return 0.
 340                  */
 341                 if (!PageUptodate(page) && copied < count)
 342                         copied = 0;
 343
 344                 iov_iter_advance(i, copied);
 345                 write_bytes -= copied;
 346                 total_copied += copied;
 347
 348                 /* Return to btrfs_file_aio_write to fault page */
 349                 if (unlikely(copied == 0))
 350                         break;
 351
 352                 if (unlikely(copied < PAGE_CACHE_SIZE - offset)) {
 353                         offset += copied;
 354                 } else {
 355                         pg++;
 356                         offset = 0;
 357                 }
 358         }
 359         return total_copied;
 360 }
 361
 362 /*
 363  * unlocks pages after btrfs_file_write is done with them
 364  */
 365 void btrfs_drop_pages(struct page **pages, size_t num_pages)
 366 {
 367         size_t i;
 368         for (i = 0; i < num_pages; i++) {
 369                 /* page checked is some magic around finding pages that
 370                  * have been modified without going through btrfs_set_page_dirty
 371                  * clear it here
 372                  */
 373                 ClearPageChecked(pages[i]);
 374                 unlock_page(pages[i]);
 375                 mark_page_accessed(pages[i]);
 376                 page_cache_release(pages[i]);
 377         }
 378 }
 379
 380 /*
 381  * after copy_from_user, pages need to be dirtied and we need to make
 382  * sure holes are created between the current EOF and the start of
 383  * any next extents (if required).
 384  *
 385  * this also makes the decision about creating an inline extent vs
 386  * doing real data extents, marking pages dirty and delalloc as required.
 387  */
 388 int btrfs_dirty_pages(struct btrfs_root *root, struct inode *inode,
 389                       struct page **pages, size_t num_pages,
 390                       loff_t pos, size_t write_bytes,
 391                       struct extent_state **cached)
 392 {
 393         int err = 0;
 394         int i;
 395         u64 num_bytes;
 396         u64 start_pos;
 397         u64 end_of_last_block;
 398         u64 end_pos = pos + write_bytes;
 399         loff_t isize = i_size_read(inode);
 400
 401         start_pos = pos & ~((u64)root->sectorsize - 1);
 402         num_bytes = (write_bytes + pos - start_pos +
 403                     root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
 404
 405         end_of_last_block = start_pos + num_bytes - 1;
 406         err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block,
 407                                         cached);
 408         if (err)
 409                 return err;
 410
 411         for (i = 0; i < num_pages; i++) {
 412                 struct page *p = pages[i];
 413                 SetPageUptodate(p);
 414                 ClearPageChecked(p);
 415                 set_page_dirty(p);
 416         }
 417
 418         /*
 419          * we've only changed i_size in ram, and we haven't updated
 420          * the disk i_size.  There is no need to log the inode
 421          * at this time.
 422          */
 423         if (end_pos > isize)
 424                 i_size_write(inode, end_pos);
 425         return 0;
 426 }
 427
 428 /*
 429  * this drops all the extents in the cache that intersect the range
 430  * [start, end].  Existing extents are split as required.
 431  */
 432 int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
 433                             int skip_pinned)
 434 {
 435         struct extent_map *em;
 436         struct extent_map *split = NULL;
 437         struct extent_map *split2 = NULL;
 438         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
 439         u64 len = end - start + 1;
 440         int ret;
 441         int testend = 1;
 442         unsigned long flags;
 443         int compressed = 0;
 444
 445         WARN_ON(end < start);
 446         if (end == (u64)-1) {
 447                 len = (u64)-1;
 448                 testend = 0;
 449         }
 450         while (1) {
 451                 if (!split)
 452                         split = alloc_extent_map();
 453                 if (!split2)
 454                         split2 = alloc_extent_map();
 455                 BUG_ON(!split || !split2);
 456
 457                 write_lock(&em_tree->lock);
 458                 em = lookup_extent_mapping(em_tree, start, len);
 459                 if (!em) {
 460                         write_unlock(&em_tree->lock);
 461                         break;
 462                 }
 463                 flags = em->flags;
 464                 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
 465                         if (testend && em->start + em->len >= start + len) {
 466                                 free_extent_map(em);
 467                                 write_unlock(&em_tree->lock);
 468                                 break;
 469                         }
 470                         start = em->start + em->len;
 471                         if (testend)
 472                                 len = start + len - (em->start + em->len);
 473                         free_extent_map(em);
 474                         write_unlock(&em_tree->lock);
 475                         continue;
 476                 }
 477                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 478                 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
 479                 remove_extent_mapping(em_tree, em);
 480
 481                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 482                     em->start < start) {
 483                         split->start = em->start;
 484                         split->len = start - em->start;
 485                         split->orig_start = em->orig_start;
 486                         split->block_start = em->block_start;
 487
 488                         if (compressed)
 489                                 split->block_len = em->block_len;
 490                         else
 491                                 split->block_len = split->len;
 492
 493                         split->bdev = em->bdev;
 494                         split->flags = flags;
 495                         split->compress_type = em->compress_type;
 496                         ret = add_extent_mapping(em_tree, split);
 497                         BUG_ON(ret);
 498                         free_extent_map(split);
 499                         split = split2;
 500                         split2 = NULL;
 501                 }
 502                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 503                     testend && em->start + em->len > start + len) {
 504                         u64 diff = start + len - em->start;
 505
 506                         split->start = start + len;
 507                         split->len = em->start + em->len - (start + len);
 508                         split->bdev = em->bdev;
 509                         split->flags = flags;
 510                         split->compress_type = em->compress_type;
 511
 512                         if (compressed) {
 513                                 split->block_len = em->block_len;
 514                                 split->block_start = em->block_start;
 515                                 split->orig_start = em->orig_start;
 516                         } else {
 517                                 split->block_len = split->len;
 518                                 split->block_start = em->block_start + diff;
 519                                 split->orig_start = split->start;
 520                         }
 521
 522                         ret = add_extent_mapping(em_tree, split);
 523                         BUG_ON(ret);
 524                         free_extent_map(split);
 525                         split = NULL;
 526                 }
 527                 write_unlock(&em_tree->lock);
 528
 529                 /* once for us */
 530                 free_extent_map(em);
 531                 /* once for the tree*/
 532                 free_extent_map(em);
 533         }
 534         if (split)
 535                 free_extent_map(split);
 536         if (split2)
 537                 free_extent_map(split2);
 538         return 0;
 539 }
 540
 541 /*
 542  * this is very complex, but the basic idea is to drop all extents
 543  * in the range start - end.  hint_block is filled in with a block number
 544  * that would be a good hint to the block allocator for this file.
 545  *
 546  * If an extent intersects the range but is not entirely inside the range
 547  * it is either truncated or split.  Anything entirely inside the range
 548  * is deleted from the tree.
 549  */
 550 int btrfs_drop_extents(struct btrfs_trans_handle *trans, struct inode *inode,
 551                        u64 start, u64 end, u64 *hint_byte, int drop_cache)
 552 {
 553         struct btrfs_root *root = BTRFS_I(inode)->root;
 554         struct extent_buffer *leaf;
 555         struct btrfs_file_extent_item *fi;
 556         struct btrfs_path *path;
 557         struct btrfs_key key;
 558         struct btrfs_key new_key;
 559         u64 ino = btrfs_ino(inode);
 560         u64 search_start = start;
 561         u64 disk_bytenr = 0;
 562         u64 num_bytes = 0;
 563         u64 extent_offset = 0;
 564         u64 extent_end = 0;
 565         int del_nr = 0;
 566         int del_slot = 0;
 567         int extent_type;
 568         int recow;
 569         int ret;
 570
 571         if (drop_cache)
 572                 btrfs_drop_extent_cache(inode, start, end - 1, 0);
 573
 574         path = btrfs_alloc_path();
 575         if (!path)
 576                 return -ENOMEM;
 577
 578         while (1) {
 579                 recow = 0;
 580                 ret = btrfs_lookup_file_extent(trans, root, path, ino,
 581                                                search_start, -1);
 582                 if (ret < 0)
 583                         break;
 584                 if (ret > 0 && path->slots[0] > 0 && search_start == start) {
 585                         leaf = path->nodes[0];
 586                         btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 587                         if (key.objectid == ino &&
 588                             key.type == BTRFS_EXTENT_DATA_KEY)
 589                                 path->slots[0]--;
 590                 }
 591                 ret = 0;
 592 next_slot:
 593                 leaf = path->nodes[0];
 594                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 595                         BUG_ON(del_nr > 0);
 596                         ret = btrfs_next_leaf(root, path);
 597                         if (ret < 0)
 598                                 break;
 599                         if (ret > 0) {
 600                                 ret = 0;
 601                                 break;
 602                         }
 603                         leaf = path->nodes[0];
 604                         recow = 1;
 605                 }
 606
 607                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 608                 if (key.objectid > ino ||
 609                     key.type > BTRFS_EXTENT_DATA_KEY || key.offset >= end)
 610                         break;
 611
 612                 fi = btrfs_item_ptr(leaf, path->slots[0],
 613                                     struct btrfs_file_extent_item);
 614                 extent_type = btrfs_file_extent_type(leaf, fi);
 615
 616                 if (extent_type == BTRFS_FILE_EXTENT_REG ||
 617                     extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
 618                         disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 619                         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
 620                         extent_offset = btrfs_file_extent_offset(leaf, fi);
 621                         extent_end = key.offset +
 622                                 btrfs_file_extent_num_bytes(leaf, fi);
 623                 } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 624                         extent_end = key.offset +
 625                                 btrfs_file_extent_inline_len(leaf, fi);
 626                 } else {
 627                         WARN_ON(1);
 628                         extent_end = search_start;
 629                 }
 630
 631                 if (extent_end <= search_start) {
 632                         path->slots[0]++;
 633                         goto next_slot;
 634                 }
 635
 636                 search_start = max(key.offset, start);
 637                 if (recow) {
 638                         btrfs_release_path(path);
 639                         continue;
 640                 }
 641
 642                 /*
 643                  *     | - range to drop - |
 644                  *  | -------- extent -------- |
 645                  */
 646                 if (start > key.offset && end < extent_end) {
 647                         BUG_ON(del_nr > 0);
 648                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 649
 650                         memcpy(&new_key, &key, sizeof(new_key));
 651                         new_key.offset = start;
 652                         ret = btrfs_duplicate_item(trans, root, path,
 653                                                    &new_key);
 654                         if (ret == -EAGAIN) {
 655                                 btrfs_release_path(path);
 656                                 continue;
 657                         }
 658                         if (ret < 0)
 659                                 break;
 660
 661                         leaf = path->nodes[0];
 662                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
 663                                             struct btrfs_file_extent_item);
 664                         btrfs_set_file_extent_num_bytes(leaf, fi,
 665                                                         start - key.offset);
 666
 667                         fi = btrfs_item_ptr(leaf, path->slots[0],
 668                                             struct btrfs_file_extent_item);
 669
 670                         extent_offset += start - key.offset;
 671                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
 672                         btrfs_set_file_extent_num_bytes(leaf, fi,
 673                                                         extent_end - start);
 674                         btrfs_mark_buffer_dirty(leaf);
 675
 676                         if (disk_bytenr > 0) {
 677                                 ret = btrfs_inc_extent_ref(trans, root,
 678                                                 disk_bytenr, num_bytes, 0,
 679                                                 root->root_key.objectid,
 680                                                 new_key.objectid,
 681                                                 start - extent_offset);
 682                                 BUG_ON(ret);
 683                                 *hint_byte = disk_bytenr;
 684                         }
 685                         key.offset = start;
 686                 }
 687                 /*
 688                  *  | ---- range to drop ----- |
 689                  *      | -------- extent -------- |
 690                  */
 691                 if (start <= key.offset && end < extent_end) {
 692                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 693
 694                         memcpy(&new_key, &key, sizeof(new_key));
 695                         new_key.offset = end;
 696                         btrfs_set_item_key_safe(trans, root, path, &new_key);
 697
 698                         extent_offset += end - key.offset;
 699                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
 700                         btrfs_set_file_extent_num_bytes(leaf, fi,
 701                                                         extent_end - end);
 702                         btrfs_mark_buffer_dirty(leaf);
 703                         if (disk_bytenr > 0) {
 704                                 inode_sub_bytes(inode, end - key.offset);
 705                                 *hint_byte = disk_bytenr;
 706                         }
 707                         break;
 708                 }
 709
 710                 search_start = extent_end;
 711                 /*
 712                  *       | ---- range to drop ----- |
 713                  *  | -------- extent -------- |
 714                  */
 715                 if (start > key.offset && end >= extent_end) {
 716                         BUG_ON(del_nr > 0);
 717                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 718
 719                         btrfs_set_file_extent_num_bytes(leaf, fi,
 720                                                         start - key.offset);
 721                         btrfs_mark_buffer_dirty(leaf);
 722                         if (disk_bytenr > 0) {
 723                                 inode_sub_bytes(inode, extent_end - start);
 724                                 *hint_byte = disk_bytenr;
 725                         }
 726                         if (end == extent_end)
 727                                 break;
 728
 729                         path->slots[0]++;
 730                         goto next_slot;
 731                 }
 732
 733                 /*
 734                  *  | ---- range to drop ----- |
 735                  *    | ------ extent ------ |
 736                  */
 737                 if (start <= key.offset && end >= extent_end) {
 738                         if (del_nr == 0) {
 739                                 del_slot = path->slots[0];
 740                                 del_nr = 1;
 741                         } else {
 742                                 BUG_ON(del_slot + del_nr != path->slots[0]);
 743                                 del_nr++;
 744                         }
 745
 746                         if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 747                                 inode_sub_bytes(inode,
 748                                                 extent_end - key.offset);
 749                                 extent_end = ALIGN(extent_end,
 750                                                    root->sectorsize);
 751                         } else if (disk_bytenr > 0) {
 752                                 ret = btrfs_free_extent(trans, root,
 753                                                 disk_bytenr, num_bytes, 0,
 754                                                 root->root_key.objectid,
 755                                                 key.objectid, key.offset -
 756                                                 extent_offset);
 757                                 BUG_ON(ret);
 758                                 inode_sub_bytes(inode,
 759                                                 extent_end - key.offset);
 760                                 *hint_byte = disk_bytenr;
 761                         }
 762
 763                         if (end == extent_end)
 764                                 break;
 765
 766                         if (path->slots[0] + 1 < btrfs_header_nritems(leaf)) {
 767                                 path->slots[0]++;
 768                                 goto next_slot;
 769                         }
 770
 771                         ret = btrfs_del_items(trans, root, path, del_slot,
 772                                               del_nr);
 773                         BUG_ON(ret);
 774
 775                         del_nr = 0;
 776                         del_slot = 0;
 777
 778                         btrfs_release_path(path);
 779                         continue;
 780                 }
 781
 782                 BUG_ON(1);
 783         }
 784
 785         if (del_nr > 0) {
 786                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
 787                 BUG_ON(ret);
 788         }
 789
 790         btrfs_free_path(path);
 791         return ret;
 792 }
 793
 794 static int extent_mergeable(struct extent_buffer *leaf, int slot,
 795                             u64 objectid, u64 bytenr, u64 orig_offset,
 796                             u64 *start, u64 *end)
 797 {
 798         struct btrfs_file_extent_item *fi;
 799         struct btrfs_key key;
 800         u64 extent_end;
 801
 802         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
 803                 return 0;
 804
 805         btrfs_item_key_to_cpu(leaf, &key, slot);
 806         if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
 807                 return 0;
 808
 809         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
 810         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
 811             btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
 812             btrfs_file_extent_offset(leaf, fi) != key.offset - orig_offset ||
 813             btrfs_file_extent_compression(leaf, fi) ||
 814             btrfs_file_extent_encryption(leaf, fi) ||
 815             btrfs_file_extent_other_encoding(leaf, fi))
 816                 return 0;
 817
 818         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 819         if ((*start && *start != key.offset) || (*end && *end != extent_end))
 820                 return 0;
 821
 822         *start = key.offset;
 823         *end = extent_end;
 824         return 1;
 825 }
 826
 827 /*
 828  * Mark extent in the range start - end as written.
 829  *
 830  * This changes extent type from 'pre-allocated' to 'regular'. If only
 831  * part of extent is marked as written, the extent will be split into
 832  * two or three.
 833  */
 834 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
 835                               struct inode *inode, u64 start, u64 end)
 836 {
 837         struct btrfs_root *root = BTRFS_I(inode)->root;
 838         struct extent_buffer *leaf;
 839         struct btrfs_path *path;
 840         struct btrfs_file_extent_item *fi;
 841         struct btrfs_key key;
 842         struct btrfs_key new_key;
 843         u64 bytenr;
 844         u64 num_bytes;
 845         u64 extent_end;
 846         u64 orig_offset;
 847         u64 other_start;
 848         u64 other_end;
 849         u64 split;
 850         int del_nr = 0;
 851         int del_slot = 0;
 852         int recow;
 853         int ret;
 854         u64 ino = btrfs_ino(inode);
 855
 856         btrfs_drop_extent_cache(inode, start, end - 1, 0);
 857
 858         path = btrfs_alloc_path();
 859         if (!path)
 860                 return -ENOMEM;
 861 again:
 862         recow = 0;
 863         split = start;
 864         key.objectid = ino;
 865         key.type = BTRFS_EXTENT_DATA_KEY;
 866         key.offset = split;
 867
 868         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 869         if (ret < 0)
 870                 goto out;
 871         if (ret > 0 && path->slots[0] > 0)
 872                 path->slots[0]--;
 873
 874         leaf = path->nodes[0];
 875         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 876         BUG_ON(key.objectid != ino || key.type != BTRFS_EXTENT_DATA_KEY);
 877         fi = btrfs_item_ptr(leaf, path->slots[0],
 878                             struct btrfs_file_extent_item);
 879         BUG_ON(btrfs_file_extent_type(leaf, fi) !=
 880                BTRFS_FILE_EXTENT_PREALLOC);
 881         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 882         BUG_ON(key.offset > start || extent_end < end);
 883
 884         bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 885         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
 886         orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
 887         memcpy(&new_key, &key, sizeof(new_key));
 888
 889         if (start == key.offset && end < extent_end) {
 890                 other_start = 0;
 891                 other_end = start;
 892                 if (extent_mergeable(leaf, path->slots[0] - 1,
 893                                      ino, bytenr, orig_offset,
 894                                      &other_start, &other_end)) {
 895                         new_key.offset = end;
 896                         btrfs_set_item_key_safe(trans, root, path, &new_key);
 897                         fi = btrfs_item_ptr(leaf, path->slots[0],
 898                                             struct btrfs_file_extent_item);
 899                         btrfs_set_file_extent_num_bytes(leaf, fi,
 900                                                         extent_end - end);
 901                         btrfs_set_file_extent_offset(leaf, fi,
 902                                                      end - orig_offset);
 903                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
 904                                             struct btrfs_file_extent_item);
 905                         btrfs_set_file_extent_num_bytes(leaf, fi,
 906                                                         end - other_start);
 907                         btrfs_mark_buffer_dirty(leaf);
 908                         goto out;
 909                 }
 910         }
 911
 912         if (start > key.offset && end == extent_end) {
 913                 other_start = end;
 914                 other_end = 0;
 915                 if (extent_mergeable(leaf, path->slots[0] + 1,
 916                                      ino, bytenr, orig_offset,
 917                                      &other_start, &other_end)) {
 918                         fi = btrfs_item_ptr(leaf, path->slots[0],
 919                                             struct btrfs_file_extent_item);
 920                         btrfs_set_file_extent_num_bytes(leaf, fi,
 921                                                         start - key.offset);
 922                         path->slots[0]++;
 923                         new_key.offset = start;
 924                         btrfs_set_item_key_safe(trans, root, path, &new_key);
 925
 926                         fi = btrfs_item_ptr(leaf, path->slots[0],
 927                                             struct btrfs_file_extent_item);
 928                         btrfs_set_file_extent_num_bytes(leaf, fi,
 929                                                         other_end - start);
 930                         btrfs_set_file_extent_offset(leaf, fi,
 931                                                      start - orig_offset);
 932                         btrfs_mark_buffer_dirty(leaf);
 933                         goto out;
 934                 }
 935         }
 936
 937         while (start > key.offset || end < extent_end) {
 938                 if (key.offset == start)
 939                         split = end;
 940
 941                 new_key.offset = split;
 942                 ret = btrfs_duplicate_item(trans, root, path, &new_key);
 943                 if (ret == -EAGAIN) {
 944                         btrfs_release_path(path);
 945                         goto again;
 946                 }
 947                 BUG_ON(ret < 0);
 948
 949                 leaf = path->nodes[0];
 950                 fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
 951                                     struct btrfs_file_extent_item);
 952                 btrfs_set_file_extent_num_bytes(leaf, fi,
 953                                                 split - key.offset);
 954
 955                 fi = btrfs_item_ptr(leaf, path->slots[0],
 956                                     struct btrfs_file_extent_item);
 957
 958                 btrfs_set_file_extent_offset(leaf, fi, split - orig_offset);
 959                 btrfs_set_file_extent_num_bytes(leaf, fi,
 960                                                 extent_end - split);
 961                 btrfs_mark_buffer_dirty(leaf);
 962
 963                 ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
 964                                            root->root_key.objectid,
 965                                            ino, orig_offset);
 966                 BUG_ON(ret);
 967
 968                 if (split == start) {
 969                         key.offset = start;
 970                 } else {
 971                         BUG_ON(start != key.offset);
 972                         path->slots[0]--;
 973                         extent_end = end;
 974                 }
 975                 recow = 1;
 976         }
 977
 978         other_start = end;
 979         other_end = 0;
 980         if (extent_mergeable(leaf, path->slots[0] + 1,
 981                              ino, bytenr, orig_offset,
 982                              &other_start, &other_end)) {
 983                 if (recow) {
 984                         btrfs_release_path(path);
 985                         goto again;
 986                 }
 987                 extent_end = other_end;
 988                 del_slot = path->slots[0] + 1;
 989                 del_nr++;
 990                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
 991                                         0, root->root_key.objectid,
 992                                         ino, orig_offset);
 993                 BUG_ON(ret);
 994         }
 995         other_start = 0;
 996         other_end = start;
 997         if (extent_mergeable(leaf, path->slots[0] - 1,
 998                              ino, bytenr, orig_offset,
 999                              &other_start, &other_end)) {
1000                 if (recow) {
1001                         btrfs_release_path(path);
1002                         goto again;
1003                 }
1004                 key.offset = other_start;
1005                 del_slot = path->slots[0];
1006                 del_nr++;
1007                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1008                                         0, root->root_key.objectid,
1009                                         ino, orig_offset);
1010                 BUG_ON(ret);
1011         }
1012         if (del_nr == 0) {
1013                 fi = btrfs_item_ptr(leaf, path->slots[0],
1014                            struct btrfs_file_extent_item);
1015                 btrfs_set_file_extent_type(leaf, fi,
1016                                            BTRFS_FILE_EXTENT_REG);
1017                 btrfs_mark_buffer_dirty(leaf);
1018         } else {
1019                 fi = btrfs_item_ptr(leaf, del_slot - 1,
1020                            struct btrfs_file_extent_item);
1021                 btrfs_set_file_extent_type(leaf, fi,
1022                                            BTRFS_FILE_EXTENT_REG);
1023                 btrfs_set_file_extent_num_bytes(leaf, fi,
1024                                                 extent_end - key.offset);
1025                 btrfs_mark_buffer_dirty(leaf);
1026
1027                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
1028                 BUG_ON(ret);
1029         }
1030 out:
1031         btrfs_free_path(path);
1032         return 0;
1033 }
1034
1035 /*
1036  * on error we return an unlocked page and the error value
1037  * on success we return a locked page and 0
1038  */
1039 static int prepare_uptodate_page(struct page *page, u64 pos,
1040                                  bool force_uptodate)
1041 {
1042         int ret = 0;
1043
1044         if (((pos & (PAGE_CACHE_SIZE - 1)) || force_uptodate) &&
1045             !PageUptodate(page)) {
1046                 ret = btrfs_readpage(NULL, page);
1047                 if (ret)
1048                         return ret;
1049                 lock_page(page);
1050                 if (!PageUptodate(page)) {
1051                         unlock_page(page);
1052                         return -EIO;
1053                 }
1054         }
1055         return 0;
1056 }
1057
1058 /*
1059  * this gets pages into the page cache and locks them down, it also properly
1060  * waits for data=ordered extents to finish before allowing the pages to be
1061  * modified.
1062  */
1063 static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
1064                          struct page **pages, size_t num_pages,
1065                          loff_t pos, unsigned long first_index,
1066                          size_t write_bytes, bool force_uptodate)
1067 {
1068         struct extent_state *cached_state = NULL;
1069         int i;
1070         unsigned long index = pos >> PAGE_CACHE_SHIFT;
1071         struct inode *inode = fdentry(file)->d_inode;
1072         int err = 0;
1073         int faili = 0;
1074         u64 start_pos;
1075         u64 last_pos;
1076
1077         start_pos = pos & ~((u64)root->sectorsize - 1);
1078         last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
1079
1080 again:
1081         for (i = 0; i < num_pages; i++) {
1082                 pages[i] = find_or_create_page(inode->i_mapping, index + i,
1083                                                GFP_NOFS);
1084                 if (!pages[i]) {
1085                         faili = i - 1;
1086                         err = -ENOMEM;
1087                         goto fail;
1088                 }
1089
1090                 if (i == 0)
1091                         err = prepare_uptodate_page(pages[i], pos,
1092                                                     force_uptodate);
1093                 if (i == num_pages - 1)
1094                         err = prepare_uptodate_page(pages[i],
1095                                                     pos + write_bytes, false);
1096                 if (err) {
1097                         page_cache_release(pages[i]);
1098                         faili = i - 1;
1099                         goto fail;
1100                 }
1101                 wait_on_page_writeback(pages[i]);
1102         }
1103         err = 0;
1104         if (start_pos < inode->i_size) {
1105                 struct btrfs_ordered_extent *ordered;
1106                 lock_extent_bits(&BTRFS_I(inode)->io_tree,
1107                                  start_pos, last_pos - 1, 0, &cached_state,
1108                                  GFP_NOFS);
1109                 ordered = btrfs_lookup_first_ordered_extent(inode,
1110                                                             last_pos - 1);
1111                 if (ordered &&
1112                     ordered->file_offset + ordered->len > start_pos &&
1113                     ordered->file_offset < last_pos) {
1114                         btrfs_put_ordered_extent(ordered);
1115                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1116                                              start_pos, last_pos - 1,
1117                                              &cached_state, GFP_NOFS);
1118                         for (i = 0; i < num_pages; i++) {
1119                                 unlock_page(pages[i]);
1120                                 page_cache_release(pages[i]);
1121                         }
1122                         btrfs_wait_ordered_range(inode, start_pos,
1123                                                  last_pos - start_pos);
1124                         goto again;
1125                 }
1126                 if (ordered)
1127                         btrfs_put_ordered_extent(ordered);
1128
1129                 clear_extent_bit(&BTRFS_I(inode)->io_tree, start_pos,
1130                                   last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC |
1131                                   EXTENT_DO_ACCOUNTING, 0, 0, &cached_state,
1132                                   GFP_NOFS);
1133                 unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1134                                      start_pos, last_pos - 1, &cached_state,
1135                                      GFP_NOFS);
1136         }
1137         for (i = 0; i < num_pages; i++) {
1138                 clear_page_dirty_for_io(pages[i]);
1139                 set_page_extent_mapped(pages[i]);
1140                 WARN_ON(!PageLocked(pages[i]));
1141         }
1142         return 0;
1143 fail:
1144         while (faili >= 0) {
1145                 unlock_page(pages[faili]);
1146                 page_cache_release(pages[faili]);
1147                 faili--;
1148         }
1149         return err;
1150
1151 }
1152
1153 static noinline ssize_t __btrfs_buffered_write(struct file *file,
1154                                                struct iov_iter *i,
1155                                                loff_t pos)
1156 {
1157         struct inode *inode = fdentry(file)->d_inode;
1158         struct btrfs_root *root = BTRFS_I(inode)->root;
1159         struct page **pages = NULL;
1160         unsigned long first_index;
1161         size_t num_written = 0;
1162         int nrptrs;
1163         int ret = 0;
1164         bool force_page_uptodate = false;
1165
1166         nrptrs = min((iov_iter_count(i) + PAGE_CACHE_SIZE - 1) /
1167                      PAGE_CACHE_SIZE, PAGE_CACHE_SIZE /
1168                      (sizeof(struct page *)));
1169         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
1170         if (!pages)
1171                 return -ENOMEM;
1172
1173         first_index = pos >> PAGE_CACHE_SHIFT;
1174
1175         while (iov_iter_count(i) > 0) {
1176                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
1177                 size_t write_bytes = min(iov_iter_count(i),
1178                                          nrptrs * (size_t)PAGE_CACHE_SIZE -
1179                                          offset);
1180                 size_t num_pages = (write_bytes + offset +
1181                                     PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1182                 size_t dirty_pages;
1183                 size_t copied;
1184
1185                 WARN_ON(num_pages > nrptrs);
1186
1187                 /*
1188                  * Fault pages before locking them in prepare_pages
1189                  * to avoid recursive lock
1190                  */
1191                 if (unlikely(iov_iter_fault_in_readable(i, write_bytes))) {
1192                         ret = -EFAULT;
1193                         break;
1194                 }
1195
1196                 ret = btrfs_delalloc_reserve_space(inode,
1197                                         num_pages << PAGE_CACHE_SHIFT);
1198                 if (ret)
1199                         break;
1200
1201                 /*
1202                  * This is going to setup the pages array with the number of
1203                  * pages we want, so we don't really need to worry about the
1204                  * contents of pages from loop to loop
1205                  */
1206                 ret = prepare_pages(root, file, pages, num_pages,
1207                                     pos, first_index, write_bytes,
1208                                     force_page_uptodate);
1209                 if (ret) {
1210                         btrfs_delalloc_release_space(inode,
1211                                         num_pages << PAGE_CACHE_SHIFT);
1212                         break;
1213                 }
1214
1215                 copied = btrfs_copy_from_user(pos, num_pages,
1216                                            write_bytes, pages, i);
1217
1218                 /*
1219                  * if we have trouble faulting in the pages, fall
1220                  * back to one page at a time
1221                  */
1222                 if (copied < write_bytes)
1223                         nrptrs = 1;
1224
1225                 if (copied == 0) {
1226                         force_page_uptodate = true;
1227                         dirty_pages = 0;
1228                 } else {
1229                         force_page_uptodate = false;
1230                         dirty_pages = (copied + offset +
1231                                        PAGE_CACHE_SIZE - 1) >>
1232                                        PAGE_CACHE_SHIFT;
1233                 }
1234
1235                 /*
1236                  * If we had a short copy we need to release the excess delaloc
1237                  * bytes we reserved.  We need to increment outstanding_extents
1238                  * because btrfs_delalloc_release_space will decrement it, but
1239                  * we still have an outstanding extent for the chunk we actually
1240                  * managed to copy.
1241                  */
1242                 if (num_pages > dirty_pages) {
1243                         if (copied > 0) {
1244                                 spin_lock(&BTRFS_I(inode)->lock);
1245                                 BTRFS_I(inode)->outstanding_extents++;
1246                                 spin_unlock(&BTRFS_I(inode)->lock);
1247                         }
1248                         btrfs_delalloc_release_space(inode,
1249                                         (num_pages - dirty_pages) <<
1250                                         PAGE_CACHE_SHIFT);
1251                 }
1252
1253                 if (copied > 0) {
1254                         ret = btrfs_dirty_pages(root, inode, pages,
1255                                                 dirty_pages, pos, copied,
1256                                                 NULL);
1257                         if (ret) {
1258                                 btrfs_delalloc_release_space(inode,
1259                                         dirty_pages << PAGE_CACHE_SHIFT);
1260                                 btrfs_drop_pages(pages, num_pages);
1261                                 break;
1262                         }
1263                 }
1264
1265                 btrfs_drop_pages(pages, num_pages);
1266
1267                 cond_resched();
1268
1269                 balance_dirty_pages_ratelimited_nr(inode->i_mapping,
1270                                                    dirty_pages);
1271                 if (dirty_pages < (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
1272                         btrfs_btree_balance_dirty(root, 1);
1273                 btrfs_throttle(root);
1274
1275                 pos += copied;
1276                 num_written += copied;
1277         }
1278
1279         kfree(pages);
1280
1281         return num_written ? num_written : ret;
1282 }
1283
1284 static ssize_t __btrfs_direct_write(struct kiocb *iocb,
1285                                     const struct iovec *iov,
1286                                     unsigned long nr_segs, loff_t pos,
1287                                     loff_t *ppos, size_t count, size_t ocount)
1288 {
1289         struct file *file = iocb->ki_filp;
1290         struct inode *inode = fdentry(file)->d_inode;
1291         struct iov_iter i;
1292         ssize_t written;
1293         ssize_t written_buffered;
1294         loff_t endbyte;
1295         int err;
1296
1297         written = generic_file_direct_write(iocb, iov, &nr_segs, pos, ppos,
1298                                             count, ocount);
1299
1300         /*
1301          * the generic O_DIRECT will update in-memory i_size after the
1302          * DIOs are done.  But our endio handlers that update the on
1303          * disk i_size never update past the in memory i_size.  So we
1304          * need one more update here to catch any additions to the
1305          * file
1306          */
1307         if (inode->i_size != BTRFS_I(inode)->disk_i_size) {
1308                 btrfs_ordered_update_i_size(inode, inode->i_size, NULL);
1309                 mark_inode_dirty(inode);
1310         }
1311
1312         if (written < 0 || written == count)
1313                 return written;
1314
1315         pos += written;
1316         count -= written;
1317         iov_iter_init(&i, iov, nr_segs, count, written);
1318         written_buffered = __btrfs_buffered_write(file, &i, pos);
1319         if (written_buffered < 0) {
1320                 err = written_buffered;
1321                 goto out;
1322         }
1323         endbyte = pos + written_buffered - 1;
1324         err = filemap_write_and_wait_range(file->f_mapping, pos, endbyte);
1325         if (err)
1326                 goto out;
1327         written += written_buffered;
1328         *ppos = pos + written_buffered;
1329         invalidate_mapping_pages(file->f_mapping, pos >> PAGE_CACHE_SHIFT,
1330                                  endbyte >> PAGE_CACHE_SHIFT);
1331 out:
1332         return written ? written : err;
1333 }
1334
1335 static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
1336                                     const struct iovec *iov,
1337                                     unsigned long nr_segs, loff_t pos)
1338 {
1339         struct file *file = iocb->ki_filp;
1340         struct inode *inode = fdentry(file)->d_inode;
1341         struct btrfs_root *root = BTRFS_I(inode)->root;
1342         loff_t *ppos = &iocb->ki_pos;
1343         u64 start_pos;
1344         ssize_t num_written = 0;
1345         ssize_t err = 0;
1346         size_t count, ocount;
1347
1348         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
1349
1350         mutex_lock(&inode->i_mutex);
1351
1352         err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
1353         if (err) {
1354                 mutex_unlock(&inode->i_mutex);
1355                 goto out;
1356         }
1357         count = ocount;
1358
1359         current->backing_dev_info = inode->i_mapping->backing_dev_info;
1360         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
1361         if (err) {
1362                 mutex_unlock(&inode->i_mutex);
1363                 goto out;
1364         }
1365
1366         if (count == 0) {
1367                 mutex_unlock(&inode->i_mutex);
1368                 goto out;
1369         }
1370
1371         err = file_remove_suid(file);
1372         if (err) {
1373                 mutex_unlock(&inode->i_mutex);
1374                 goto out;
1375         }
1376
1377         /*
1378          * If BTRFS flips readonly due to some impossible error
1379          * (fs_info->fs_state now has BTRFS_SUPER_FLAG_ERROR),
1380          * although we have opened a file as writable, we have
1381          * to stop this write operation to ensure FS consistency.
1382          */
1383         if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
1384                 mutex_unlock(&inode->i_mutex);
1385                 err = -EROFS;
1386                 goto out;
1387         }
1388
1389         file_update_time(file);
1390         BTRFS_I(inode)->sequence++;
1391
1392         start_pos = round_down(pos, root->sectorsize);
1393         if (start_pos > i_size_read(inode)) {
1394                 err = btrfs_cont_expand(inode, i_size_read(inode), start_pos);
1395                 if (err) {
1396                         mutex_unlock(&inode->i_mutex);
1397                         goto out;
1398                 }
1399         }
1400
1401         if (unlikely(file->f_flags & O_DIRECT)) {
1402                 num_written = __btrfs_direct_write(iocb, iov, nr_segs,
1403                                                    pos, ppos, count, ocount);
1404         } else {
1405                 struct iov_iter i;
1406
1407                 iov_iter_init(&i, iov, nr_segs, count, num_written);
1408
1409                 num_written = __btrfs_buffered_write(file, &i, pos);
1410                 if (num_written > 0)
1411                         *ppos = pos + num_written;
1412         }
1413
1414         mutex_unlock(&inode->i_mutex);
1415
1416         /*
1417          * we want to make sure fsync finds this change
1418          * but we haven't joined a transaction running right now.
1419          *
1420          * Later on, someone is sure to update the inode and get the
1421          * real transid recorded.
1422          *
1423          * We set last_trans now to the fs_info generation + 1,
1424          * this will either be one more than the running transaction
1425          * or the generation used for the next transaction if there isn't
1426          * one running right now.
1427          */
1428         BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
1429         if (num_written > 0 || num_written == -EIOCBQUEUED) {
1430                 err = generic_write_sync(file, pos, num_written);
1431                 if (err < 0 && num_written > 0)
1432                         num_written = err;
1433         }
1434 out:
1435         current->backing_dev_info = NULL;
1436         return num_written ? num_written : err;
1437 }
1438
1439 int btrfs_release_file(struct inode *inode, struct file *filp)
1440 {
1441         /*
1442          * ordered_data_close is set by settattr when we are about to truncate
1443          * a file from a non-zero size to a zero size.  This tries to
1444          * flush down new bytes that may have been written if the
1445          * application were using truncate to replace a file in place.
1446          */
1447         if (BTRFS_I(inode)->ordered_data_close) {
1448                 BTRFS_I(inode)->ordered_data_close = 0;
1449                 btrfs_add_ordered_operation(NULL, BTRFS_I(inode)->root, inode);
1450                 if (inode->i_size > BTRFS_ORDERED_OPERATIONS_FLUSH_LIMIT)
1451                         filemap_flush(inode->i_mapping);
1452         }
1453         if (filp->private_data)
1454                 btrfs_ioctl_trans_end(filp);
1455         return 0;
1456 }
1457
1458 /*
1459  * fsync call for both files and directories.  This logs the inode into
1460  * the tree log instead of forcing full commits whenever possible.
1461  *
1462  * It needs to call filemap_fdatawait so that all ordered extent updates are
1463  * in the metadata btree are up to date for copying to the log.
1464  *
1465  * It drops the inode mutex before doing the tree log commit.  This is an
1466  * important optimization for directories because holding the mutex prevents
1467  * new operations on the dir while we write to disk.
1468  */
1469 int btrfs_sync_file(struct file *file, int datasync)
1470 {
1471         struct dentry *dentry = file->f_path.dentry;
1472         struct inode *inode = dentry->d_inode;
1473         struct btrfs_root *root = BTRFS_I(inode)->root;
1474         int ret = 0;
1475         struct btrfs_trans_handle *trans;
1476
1477         trace_btrfs_sync_file(file, datasync);
1478
1479         /* we wait first, since the writeback may change the inode */
1480         root->log_batch++;
1481         /* the VFS called filemap_fdatawrite for us */
1482         btrfs_wait_ordered_range(inode, 0, (u64)-1);
1483         root->log_batch++;
1484
1485         /*
1486          * check the transaction that last modified this inode
1487          * and see if its already been committed
1488          */
1489         if (!BTRFS_I(inode)->last_trans)
1490                 goto out;
1491
1492         /*
1493          * if the last transaction that changed this file was before
1494          * the current transaction, we can bail out now without any
1495          * syncing
1496          */
1497         smp_mb();
1498         if (BTRFS_I(inode)->last_trans <=
1499             root->fs_info->last_trans_committed) {
1500                 BTRFS_I(inode)->last_trans = 0;
1501                 goto out;
1502         }
1503
1504         /*
1505          * ok we haven't committed the transaction yet, lets do a commit
1506          */
1507         if (file->private_data)
1508                 btrfs_ioctl_trans_end(file);
1509
1510         trans = btrfs_start_transaction(root, 0);
1511         if (IS_ERR(trans)) {
1512                 ret = PTR_ERR(trans);
1513                 goto out;
1514         }
1515
1516         ret = btrfs_log_dentry_safe(trans, root, dentry);
1517         if (ret < 0)
1518                 goto out;
1519
1520         /* we've logged all the items and now have a consistent
1521          * version of the file in the log.  It is possible that
1522          * someone will come in and modify the file, but that's
1523          * fine because the log is consistent on disk, and we
1524          * have references to all of the file's extents
1525          *
1526          * It is possible that someone will come in and log the
1527          * file again, but that will end up using the synchronization
1528          * inside btrfs_sync_log to keep things safe.
1529          */
1530         mutex_unlock(&dentry->d_inode->i_mutex);
1531
1532         if (ret != BTRFS_NO_LOG_SYNC) {
1533                 if (ret > 0) {
1534                         ret = btrfs_commit_transaction(trans, root);
1535                 } else {
1536                         ret = btrfs_sync_log(trans, root);
1537                         if (ret == 0)
1538                                 ret = btrfs_end_transaction(trans, root);
1539                         else
1540                                 ret = btrfs_commit_transaction(trans, root);
1541                 }
1542         } else {
1543                 ret = btrfs_end_transaction(trans, root);
1544         }
1545         mutex_lock(&dentry->d_inode->i_mutex);
1546 out:
1547         return ret > 0 ? -EIO : ret;
1548 }
1549
1550 static const struct vm_operations_struct btrfs_file_vm_ops = {
1551         .fault          = filemap_fault,
1552         .page_mkwrite   = btrfs_page_mkwrite,
1553 };
1554
1555 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
1556 {
1557         struct address_space *mapping = filp->f_mapping;
1558
1559         if (!mapping->a_ops->readpage)
1560                 return -ENOEXEC;
1561
1562         file_accessed(filp);
1563         vma->vm_ops = &btrfs_file_vm_ops;
1564         vma->vm_flags |= VM_CAN_NONLINEAR;
1565
1566         return 0;
1567 }
1568
1569 static long btrfs_fallocate(struct file *file, int mode,
1570                             loff_t offset, loff_t len)
1571 {
1572         struct inode *inode = file->f_path.dentry->d_inode;
1573         struct extent_state *cached_state = NULL;
1574         u64 cur_offset;
1575         u64 last_byte;
1576         u64 alloc_start;
1577         u64 alloc_end;
1578         u64 alloc_hint = 0;
1579         u64 locked_end;
1580         u64 mask = BTRFS_I(inode)->root->sectorsize - 1;
1581         struct extent_map *em;
1582         int ret;
1583
1584         alloc_start = offset & ~mask;
1585         alloc_end =  (offset + len + mask) & ~mask;
1586
1587         /* We only support the FALLOC_FL_KEEP_SIZE mode */
1588         if (mode & ~FALLOC_FL_KEEP_SIZE)
1589                 return -EOPNOTSUPP;
1590
1591         /*
1592          * wait for ordered IO before we have any locks.  We'll loop again
1593          * below with the locks held.
1594          */
1595         btrfs_wait_ordered_range(inode, alloc_start, alloc_end - alloc_start);
1596
1597         mutex_lock(&inode->i_mutex);
1598         ret = inode_newsize_ok(inode, alloc_end);
1599         if (ret)
1600                 goto out;
1601
1602         if (alloc_start > inode->i_size) {
1603                 ret = btrfs_cont_expand(inode, i_size_read(inode),
1604                                         alloc_start);
1605                 if (ret)
1606                         goto out;
1607         }
1608
1609         ret = btrfs_check_data_free_space(inode, alloc_end - alloc_start);
1610         if (ret)
1611                 goto out;
1612
1613         locked_end = alloc_end - 1;
1614         while (1) {
1615                 struct btrfs_ordered_extent *ordered;
1616
1617                 /* the extent lock is ordered inside the running
1618                  * transaction
1619                  */
1620                 lock_extent_bits(&BTRFS_I(inode)->io_tree, alloc_start,
1621                                  locked_end, 0, &cached_state, GFP_NOFS);
1622                 ordered = btrfs_lookup_first_ordered_extent(inode,
1623                                                             alloc_end - 1);
1624                 if (ordered &&
1625                     ordered->file_offset + ordered->len > alloc_start &&
1626                     ordered->file_offset < alloc_end) {
1627                         btrfs_put_ordered_extent(ordered);
1628                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1629                                              alloc_start, locked_end,
1630                                              &cached_state, GFP_NOFS);
1631                         /*
1632                          * we can't wait on the range with the transaction
1633                          * running or with the extent lock held
1634                          */
1635                         btrfs_wait_ordered_range(inode, alloc_start,
1636                                                  alloc_end - alloc_start);
1637                 } else {
1638                         if (ordered)
1639                                 btrfs_put_ordered_extent(ordered);
1640                         break;
1641                 }
1642         }
1643
1644         cur_offset = alloc_start;
1645         while (1) {
1646                 u64 actual_end;
1647
1648                 em = btrfs_get_extent(inode, NULL, 0, cur_offset,
1649                                       alloc_end - cur_offset, 0);
1650                 BUG_ON(IS_ERR_OR_NULL(em));
1651                 last_byte = min(extent_map_end(em), alloc_end);
1652                 actual_end = min_t(u64, extent_map_end(em), offset + len);
1653                 last_byte = (last_byte + mask) & ~mask;
1654
1655                 if (em->block_start == EXTENT_MAP_HOLE ||
1656                     (cur_offset >= inode->i_size &&
1657                      !test_bit(EXTENT_FLAG_PREALLOC, &em->flags))) {
1658                         ret = btrfs_prealloc_file_range(inode, mode, cur_offset,
1659                                                         last_byte - cur_offset,
1660                                                         1 << inode->i_blkbits,
1661                                                         offset + len,
1662                                                         &alloc_hint);
1663                         if (ret < 0) {
1664                                 free_extent_map(em);
1665                                 break;
1666                         }
1667                 } else if (actual_end > inode->i_size &&
1668                            !(mode & FALLOC_FL_KEEP_SIZE)) {
1669                         /*
1670                          * We didn't need to allocate any more space, but we
1671                          * still extended the size of the file so we need to
1672                          * update i_size.
1673                          */
1674                         inode->i_ctime = CURRENT_TIME;
1675                         i_size_write(inode, actual_end);
1676                         btrfs_ordered_update_i_size(inode, actual_end, NULL);
1677                 }
1678                 free_extent_map(em);
1679
1680                 cur_offset = last_byte;
1681                 if (cur_offset >= alloc_end) {
1682                         ret = 0;
1683                         break;
1684                 }
1685         }
1686         unlock_extent_cached(&BTRFS_I(inode)->io_tree, alloc_start, locked_end,
1687                              &cached_state, GFP_NOFS);
1688
1689         btrfs_free_reserved_data_space(inode, alloc_end - alloc_start);
1690 out:
1691         mutex_unlock(&inode->i_mutex);
1692         return ret;
1693 }
1694
1695 const struct file_operations btrfs_file_operations = {
1696         .llseek         = generic_file_llseek,
1697         .read           = do_sync_read,
1698         .write          = do_sync_write,
1699         .aio_read       = generic_file_aio_read,
1700         .splice_read    = generic_file_splice_read,
1701         .aio_write      = btrfs_file_aio_write,
1702         .mmap           = btrfs_file_mmap,
1703         .open           = generic_file_open,
1704         .release        = btrfs_release_file,
1705         .fsync          = btrfs_sync_file,
1706         .fallocate      = btrfs_fallocate,
1707         .unlocked_ioctl = btrfs_ioctl,
1708 #ifdef CONFIG_COMPAT
1709         .compat_ioctl   = btrfs_ioctl,
1710 #endif
1711 };