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         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
1073         int err = 0;
1074         int faili = 0;
1075         u64 start_pos;
1076         u64 last_pos;
1077
1078         start_pos = pos & ~((u64)root->sectorsize - 1);
1079         last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
1080
1081 again:
1082         for (i = 0; i < num_pages; i++) {
1083                 pages[i] = find_or_create_page(inode->i_mapping, index + i,
1084                                                mask);
1085                 if (!pages[i]) {
1086                         faili = i - 1;
1087                         err = -ENOMEM;
1088                         goto fail;
1089                 }
1090
1091                 if (i == 0)
1092                         err = prepare_uptodate_page(pages[i], pos,
1093                                                     force_uptodate);
1094                 if (i == num_pages - 1)
1095                         err = prepare_uptodate_page(pages[i],
1096                                                     pos + write_bytes, false);
1097                 if (err) {
1098                         page_cache_release(pages[i]);
1099                         faili = i - 1;
1100                         goto fail;
1101                 }
1102                 wait_on_page_writeback(pages[i]);
1103         }
1104         err = 0;
1105         if (start_pos < inode->i_size) {
1106                 struct btrfs_ordered_extent *ordered;
1107                 lock_extent_bits(&BTRFS_I(inode)->io_tree,
1108                                  start_pos, last_pos - 1, 0, &cached_state,
1109                                  GFP_NOFS);
1110                 ordered = btrfs_lookup_first_ordered_extent(inode,
1111                                                             last_pos - 1);
1112                 if (ordered &&
1113                     ordered->file_offset + ordered->len > start_pos &&
1114                     ordered->file_offset < last_pos) {
1115                         btrfs_put_ordered_extent(ordered);
1116                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1117                                              start_pos, last_pos - 1,
1118                                              &cached_state, GFP_NOFS);
1119                         for (i = 0; i < num_pages; i++) {
1120                                 unlock_page(pages[i]);
1121                                 page_cache_release(pages[i]);
1122                         }
1123                         btrfs_wait_ordered_range(inode, start_pos,
1124                                                  last_pos - start_pos);
1125                         goto again;
1126                 }
1127                 if (ordered)
1128                         btrfs_put_ordered_extent(ordered);
1129
1130                 clear_extent_bit(&BTRFS_I(inode)->io_tree, start_pos,
1131                                   last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC |
1132                                   EXTENT_DO_ACCOUNTING, 0, 0, &cached_state,
1133                                   GFP_NOFS);
1134                 unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1135                                      start_pos, last_pos - 1, &cached_state,
1136                                      GFP_NOFS);
1137         }
1138         for (i = 0; i < num_pages; i++) {
1139                 clear_page_dirty_for_io(pages[i]);
1140                 set_page_extent_mapped(pages[i]);
1141                 WARN_ON(!PageLocked(pages[i]));
1142         }
1143         return 0;
1144 fail:
1145         while (faili >= 0) {
1146                 unlock_page(pages[faili]);
1147                 page_cache_release(pages[faili]);
1148                 faili--;
1149         }
1150         return err;
1151
1152 }
1153
1154 static noinline ssize_t __btrfs_buffered_write(struct file *file,
1155                                                struct iov_iter *i,
1156                                                loff_t pos)
1157 {
1158         struct inode *inode = fdentry(file)->d_inode;
1159         struct btrfs_root *root = BTRFS_I(inode)->root;
1160         struct page **pages = NULL;
1161         unsigned long first_index;
1162         size_t num_written = 0;
1163         int nrptrs;
1164         int ret = 0;
1165         bool force_page_uptodate = false;
1166
1167         nrptrs = min((iov_iter_count(i) + PAGE_CACHE_SIZE - 1) /
1168                      PAGE_CACHE_SIZE, PAGE_CACHE_SIZE /
1169                      (sizeof(struct page *)));
1170         nrptrs = min(nrptrs, current->nr_dirtied_pause - current->nr_dirtied);
1171         nrptrs = max(nrptrs, 8);
1172         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
1173         if (!pages)
1174                 return -ENOMEM;
1175
1176         first_index = pos >> PAGE_CACHE_SHIFT;
1177
1178         while (iov_iter_count(i) > 0) {
1179                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
1180                 size_t write_bytes = min(iov_iter_count(i),
1181                                          nrptrs * (size_t)PAGE_CACHE_SIZE -
1182                                          offset);
1183                 size_t num_pages = (write_bytes + offset +
1184                                     PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1185                 size_t dirty_pages;
1186                 size_t copied;
1187
1188                 WARN_ON(num_pages > nrptrs);
1189
1190                 /*
1191                  * Fault pages before locking them in prepare_pages
1192                  * to avoid recursive lock
1193                  */
1194                 if (unlikely(iov_iter_fault_in_readable(i, write_bytes))) {
1195                         ret = -EFAULT;
1196                         break;
1197                 }
1198
1199                 ret = btrfs_delalloc_reserve_space(inode,
1200                                         num_pages << PAGE_CACHE_SHIFT);
1201                 if (ret)
1202                         break;
1203
1204                 /*
1205                  * This is going to setup the pages array with the number of
1206                  * pages we want, so we don't really need to worry about the
1207                  * contents of pages from loop to loop
1208                  */
1209                 ret = prepare_pages(root, file, pages, num_pages,
1210                                     pos, first_index, write_bytes,
1211                                     force_page_uptodate);
1212                 if (ret) {
1213                         btrfs_delalloc_release_space(inode,
1214                                         num_pages << PAGE_CACHE_SHIFT);
1215                         break;
1216                 }
1217
1218                 copied = btrfs_copy_from_user(pos, num_pages,
1219                                            write_bytes, pages, i);
1220
1221                 /*
1222                  * if we have trouble faulting in the pages, fall
1223                  * back to one page at a time
1224                  */
1225                 if (copied < write_bytes)
1226                         nrptrs = 1;
1227
1228                 if (copied == 0) {
1229                         force_page_uptodate = true;
1230                         dirty_pages = 0;
1231                 } else {
1232                         force_page_uptodate = false;
1233                         dirty_pages = (copied + offset +
1234                                        PAGE_CACHE_SIZE - 1) >>
1235                                        PAGE_CACHE_SHIFT;
1236                 }
1237
1238                 /*
1239                  * If we had a short copy we need to release the excess delaloc
1240                  * bytes we reserved.  We need to increment outstanding_extents
1241                  * because btrfs_delalloc_release_space will decrement it, but
1242                  * we still have an outstanding extent for the chunk we actually
1243                  * managed to copy.
1244                  */
1245                 if (num_pages > dirty_pages) {
1246                         if (copied > 0) {
1247                                 spin_lock(&BTRFS_I(inode)->lock);
1248                                 BTRFS_I(inode)->outstanding_extents++;
1249                                 spin_unlock(&BTRFS_I(inode)->lock);
1250                         }
1251                         btrfs_delalloc_release_space(inode,
1252                                         (num_pages - dirty_pages) <<
1253                                         PAGE_CACHE_SHIFT);
1254                 }
1255
1256                 if (copied > 0) {
1257                         ret = btrfs_dirty_pages(root, inode, pages,
1258                                                 dirty_pages, pos, copied,
1259                                                 NULL);
1260                         if (ret) {
1261                                 btrfs_delalloc_release_space(inode,
1262                                         dirty_pages << PAGE_CACHE_SHIFT);
1263                                 btrfs_drop_pages(pages, num_pages);
1264                                 break;
1265                         }
1266                 }
1267
1268                 btrfs_drop_pages(pages, num_pages);
1269
1270                 cond_resched();
1271
1272                 balance_dirty_pages_ratelimited_nr(inode->i_mapping,
1273                                                    dirty_pages);
1274                 if (dirty_pages < (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
1275                         btrfs_btree_balance_dirty(root, 1);
1276                 btrfs_throttle(root);
1277
1278                 pos += copied;
1279                 num_written += copied;
1280         }
1281
1282         kfree(pages);
1283
1284         return num_written ? num_written : ret;
1285 }
1286
1287 static ssize_t __btrfs_direct_write(struct kiocb *iocb,
1288                                     const struct iovec *iov,
1289                                     unsigned long nr_segs, loff_t pos,
1290                                     loff_t *ppos, size_t count, size_t ocount)
1291 {
1292         struct file *file = iocb->ki_filp;
1293         struct inode *inode = fdentry(file)->d_inode;
1294         struct iov_iter i;
1295         ssize_t written;
1296         ssize_t written_buffered;
1297         loff_t endbyte;
1298         int err;
1299
1300         written = generic_file_direct_write(iocb, iov, &nr_segs, pos, ppos,
1301                                             count, ocount);
1302
1303         /*
1304          * the generic O_DIRECT will update in-memory i_size after the
1305          * DIOs are done.  But our endio handlers that update the on
1306          * disk i_size never update past the in memory i_size.  So we
1307          * need one more update here to catch any additions to the
1308          * file
1309          */
1310         if (inode->i_size != BTRFS_I(inode)->disk_i_size) {
1311                 btrfs_ordered_update_i_size(inode, inode->i_size, NULL);
1312                 mark_inode_dirty(inode);
1313         }
1314
1315         if (written < 0 || written == count)
1316                 return written;
1317
1318         pos += written;
1319         count -= written;
1320         iov_iter_init(&i, iov, nr_segs, count, written);
1321         written_buffered = __btrfs_buffered_write(file, &i, pos);
1322         if (written_buffered < 0) {
1323                 err = written_buffered;
1324                 goto out;
1325         }
1326         endbyte = pos + written_buffered - 1;
1327         err = filemap_write_and_wait_range(file->f_mapping, pos, endbyte);
1328         if (err)
1329                 goto out;
1330         written += written_buffered;
1331         *ppos = pos + written_buffered;
1332         invalidate_mapping_pages(file->f_mapping, pos >> PAGE_CACHE_SHIFT,
1333                                  endbyte >> PAGE_CACHE_SHIFT);
1334 out:
1335         return written ? written : err;
1336 }
1337
1338 static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
1339                                     const struct iovec *iov,
1340                                     unsigned long nr_segs, loff_t pos)
1341 {
1342         struct file *file = iocb->ki_filp;
1343         struct inode *inode = fdentry(file)->d_inode;
1344         struct btrfs_root *root = BTRFS_I(inode)->root;
1345         loff_t *ppos = &iocb->ki_pos;
1346         u64 start_pos;
1347         ssize_t num_written = 0;
1348         ssize_t err = 0;
1349         size_t count, ocount;
1350
1351         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
1352
1353         mutex_lock(&inode->i_mutex);
1354
1355         err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
1356         if (err) {
1357                 mutex_unlock(&inode->i_mutex);
1358                 goto out;
1359         }
1360         count = ocount;
1361
1362         current->backing_dev_info = inode->i_mapping->backing_dev_info;
1363         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
1364         if (err) {
1365                 mutex_unlock(&inode->i_mutex);
1366                 goto out;
1367         }
1368
1369         if (count == 0) {
1370                 mutex_unlock(&inode->i_mutex);
1371                 goto out;
1372         }
1373
1374         err = file_remove_suid(file);
1375         if (err) {
1376                 mutex_unlock(&inode->i_mutex);
1377                 goto out;
1378         }
1379
1380         /*
1381          * If BTRFS flips readonly due to some impossible error
1382          * (fs_info->fs_state now has BTRFS_SUPER_FLAG_ERROR),
1383          * although we have opened a file as writable, we have
1384          * to stop this write operation to ensure FS consistency.
1385          */
1386         if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
1387                 mutex_unlock(&inode->i_mutex);
1388                 err = -EROFS;
1389                 goto out;
1390         }
1391
1392         err = btrfs_update_time(file);
1393         if (err) {
1394                 mutex_unlock(&inode->i_mutex);
1395                 goto out;
1396         }
1397         BTRFS_I(inode)->sequence++;
1398
1399         start_pos = round_down(pos, root->sectorsize);
1400         if (start_pos > i_size_read(inode)) {
1401                 err = btrfs_cont_expand(inode, i_size_read(inode), start_pos);
1402                 if (err) {
1403                         mutex_unlock(&inode->i_mutex);
1404                         goto out;
1405                 }
1406         }
1407
1408         if (unlikely(file->f_flags & O_DIRECT)) {
1409                 num_written = __btrfs_direct_write(iocb, iov, nr_segs,
1410                                                    pos, ppos, count, ocount);
1411         } else {
1412                 struct iov_iter i;
1413
1414                 iov_iter_init(&i, iov, nr_segs, count, num_written);
1415
1416                 num_written = __btrfs_buffered_write(file, &i, pos);
1417                 if (num_written > 0)
1418                         *ppos = pos + num_written;
1419         }
1420
1421         mutex_unlock(&inode->i_mutex);
1422
1423         /*
1424          * we want to make sure fsync finds this change
1425          * but we haven't joined a transaction running right now.
1426          *
1427          * Later on, someone is sure to update the inode and get the
1428          * real transid recorded.
1429          *
1430          * We set last_trans now to the fs_info generation + 1,
1431          * this will either be one more than the running transaction
1432          * or the generation used for the next transaction if there isn't
1433          * one running right now.
1434          */
1435         BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
1436         if (num_written > 0 || num_written == -EIOCBQUEUED) {
1437                 err = generic_write_sync(file, pos, num_written);
1438                 if (err < 0 && num_written > 0)
1439                         num_written = err;
1440         }
1441 out:
1442         current->backing_dev_info = NULL;
1443         return num_written ? num_written : err;
1444 }
1445
1446 int btrfs_release_file(struct inode *inode, struct file *filp)
1447 {
1448         /*
1449          * ordered_data_close is set by settattr when we are about to truncate
1450          * a file from a non-zero size to a zero size.  This tries to
1451          * flush down new bytes that may have been written if the
1452          * application were using truncate to replace a file in place.
1453          */
1454         if (BTRFS_I(inode)->ordered_data_close) {
1455                 BTRFS_I(inode)->ordered_data_close = 0;
1456                 btrfs_add_ordered_operation(NULL, BTRFS_I(inode)->root, inode);
1457                 if (inode->i_size > BTRFS_ORDERED_OPERATIONS_FLUSH_LIMIT)
1458                         filemap_flush(inode->i_mapping);
1459         }
1460         if (filp->private_data)
1461                 btrfs_ioctl_trans_end(filp);
1462         return 0;
1463 }
1464
1465 /*
1466  * fsync call for both files and directories.  This logs the inode into
1467  * the tree log instead of forcing full commits whenever possible.
1468  *
1469  * It needs to call filemap_fdatawait so that all ordered extent updates are
1470  * in the metadata btree are up to date for copying to the log.
1471  *
1472  * It drops the inode mutex before doing the tree log commit.  This is an
1473  * important optimization for directories because holding the mutex prevents
1474  * new operations on the dir while we write to disk.
1475  */
1476 int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
1477 {
1478         struct dentry *dentry = file->f_path.dentry;
1479         struct inode *inode = dentry->d_inode;
1480         struct btrfs_root *root = BTRFS_I(inode)->root;
1481         int ret = 0;
1482         struct btrfs_trans_handle *trans;
1483
1484         trace_btrfs_sync_file(file, datasync);
1485
1486         ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
1487         if (ret)
1488                 return ret;
1489         mutex_lock(&inode->i_mutex);
1490
1491         /* we wait first, since the writeback may change the inode */
1492         root->log_batch++;
1493         btrfs_wait_ordered_range(inode, 0, (u64)-1);
1494         root->log_batch++;
1495
1496         /*
1497          * check the transaction that last modified this inode
1498          * and see if its already been committed
1499          */
1500         if (!BTRFS_I(inode)->last_trans) {
1501                 mutex_unlock(&inode->i_mutex);
1502                 goto out;
1503         }
1504
1505         /*
1506          * if the last transaction that changed this file was before
1507          * the current transaction, we can bail out now without any
1508          * syncing
1509          */
1510         smp_mb();
1511         if (BTRFS_I(inode)->last_trans <=
1512             root->fs_info->last_trans_committed) {
1513                 BTRFS_I(inode)->last_trans = 0;
1514                 mutex_unlock(&inode->i_mutex);
1515                 goto out;
1516         }
1517
1518         /*
1519          * ok we haven't committed the transaction yet, lets do a commit
1520          */
1521         if (file->private_data)
1522                 btrfs_ioctl_trans_end(file);
1523
1524         trans = btrfs_start_transaction(root, 0);
1525         if (IS_ERR(trans)) {
1526                 ret = PTR_ERR(trans);
1527                 mutex_unlock(&inode->i_mutex);
1528                 goto out;
1529         }
1530
1531         ret = btrfs_log_dentry_safe(trans, root, dentry);
1532         if (ret < 0) {
1533                 mutex_unlock(&inode->i_mutex);
1534                 goto out;
1535         }
1536
1537         /* we've logged all the items and now have a consistent
1538          * version of the file in the log.  It is possible that
1539          * someone will come in and modify the file, but that's
1540          * fine because the log is consistent on disk, and we
1541          * have references to all of the file's extents
1542          *
1543          * It is possible that someone will come in and log the
1544          * file again, but that will end up using the synchronization
1545          * inside btrfs_sync_log to keep things safe.
1546          */
1547         mutex_unlock(&inode->i_mutex);
1548
1549         if (ret != BTRFS_NO_LOG_SYNC) {
1550                 if (ret > 0) {
1551                         ret = btrfs_commit_transaction(trans, root);
1552                 } else {
1553                         ret = btrfs_sync_log(trans, root);
1554                         if (ret == 0)
1555                                 ret = btrfs_end_transaction(trans, root);
1556                         else
1557                                 ret = btrfs_commit_transaction(trans, root);
1558                 }
1559         } else {
1560                 ret = btrfs_end_transaction(trans, root);
1561         }
1562 out:
1563         return ret > 0 ? -EIO : ret;
1564 }
1565
1566 static const struct vm_operations_struct btrfs_file_vm_ops = {
1567         .fault          = filemap_fault,
1568         .page_mkwrite   = btrfs_page_mkwrite,
1569 };
1570
1571 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
1572 {
1573         struct address_space *mapping = filp->f_mapping;
1574
1575         if (!mapping->a_ops->readpage)
1576                 return -ENOEXEC;
1577
1578         file_accessed(filp);
1579         vma->vm_ops = &btrfs_file_vm_ops;
1580         vma->vm_flags |= VM_CAN_NONLINEAR;
1581
1582         return 0;
1583 }
1584
1585 static long btrfs_fallocate(struct file *file, int mode,
1586                             loff_t offset, loff_t len)
1587 {
1588         struct inode *inode = file->f_path.dentry->d_inode;
1589         struct extent_state *cached_state = NULL;
1590         u64 cur_offset;
1591         u64 last_byte;
1592         u64 alloc_start;
1593         u64 alloc_end;
1594         u64 alloc_hint = 0;
1595         u64 locked_end;
1596         u64 mask = BTRFS_I(inode)->root->sectorsize - 1;
1597         struct extent_map *em;
1598         int ret;
1599
1600         alloc_start = offset & ~mask;
1601         alloc_end =  (offset + len + mask) & ~mask;
1602
1603         /* We only support the FALLOC_FL_KEEP_SIZE mode */
1604         if (mode & ~FALLOC_FL_KEEP_SIZE)
1605                 return -EOPNOTSUPP;
1606
1607         /*
1608          * wait for ordered IO before we have any locks.  We'll loop again
1609          * below with the locks held.
1610          */
1611         btrfs_wait_ordered_range(inode, alloc_start, alloc_end - alloc_start);
1612
1613         mutex_lock(&inode->i_mutex);
1614         ret = inode_newsize_ok(inode, alloc_end);
1615         if (ret)
1616                 goto out;
1617
1618         if (alloc_start > inode->i_size) {
1619                 ret = btrfs_cont_expand(inode, i_size_read(inode),
1620                                         alloc_start);
1621                 if (ret)
1622                         goto out;
1623         }
1624
1625         locked_end = alloc_end - 1;
1626         while (1) {
1627                 struct btrfs_ordered_extent *ordered;
1628
1629                 /* the extent lock is ordered inside the running
1630                  * transaction
1631                  */
1632                 lock_extent_bits(&BTRFS_I(inode)->io_tree, alloc_start,
1633                                  locked_end, 0, &cached_state, GFP_NOFS);
1634                 ordered = btrfs_lookup_first_ordered_extent(inode,
1635                                                             alloc_end - 1);
1636                 if (ordered &&
1637                     ordered->file_offset + ordered->len > alloc_start &&
1638                     ordered->file_offset < alloc_end) {
1639                         btrfs_put_ordered_extent(ordered);
1640                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1641                                              alloc_start, locked_end,
1642                                              &cached_state, GFP_NOFS);
1643                         /*
1644                          * we can't wait on the range with the transaction
1645                          * running or with the extent lock held
1646                          */
1647                         btrfs_wait_ordered_range(inode, alloc_start,
1648                                                  alloc_end - alloc_start);
1649                 } else {
1650                         if (ordered)
1651                                 btrfs_put_ordered_extent(ordered);
1652                         break;
1653                 }
1654         }
1655
1656         cur_offset = alloc_start;
1657         while (1) {
1658                 u64 actual_end;
1659
1660                 em = btrfs_get_extent(inode, NULL, 0, cur_offset,
1661                                       alloc_end - cur_offset, 0);
1662                 BUG_ON(IS_ERR_OR_NULL(em));
1663                 last_byte = min(extent_map_end(em), alloc_end);
1664                 actual_end = min_t(u64, extent_map_end(em), offset + len);
1665                 last_byte = (last_byte + mask) & ~mask;
1666
1667                 if (em->block_start == EXTENT_MAP_HOLE ||
1668                     (cur_offset >= inode->i_size &&
1669                      !test_bit(EXTENT_FLAG_PREALLOC, &em->flags))) {
1670
1671                         /*
1672                          * Make sure we have enough space before we do the
1673                          * allocation.
1674                          */
1675                         ret = btrfs_check_data_free_space(inode, last_byte -
1676                                                           cur_offset);
1677                         if (ret) {
1678                                 free_extent_map(em);
1679                                 break;
1680                         }
1681
1682                         ret = btrfs_prealloc_file_range(inode, mode, cur_offset,
1683                                                         last_byte - cur_offset,
1684                                                         1 << inode->i_blkbits,
1685                                                         offset + len,
1686                                                         &alloc_hint);
1687
1688                         /* Let go of our reservation. */
1689                         btrfs_free_reserved_data_space(inode, last_byte -
1690                                                        cur_offset);
1691                         if (ret < 0) {
1692                                 free_extent_map(em);
1693                                 break;
1694                         }
1695                 } else if (actual_end > inode->i_size &&
1696                            !(mode & FALLOC_FL_KEEP_SIZE)) {
1697                         /*
1698                          * We didn't need to allocate any more space, but we
1699                          * still extended the size of the file so we need to
1700                          * update i_size.
1701                          */
1702                         inode->i_ctime = CURRENT_TIME;
1703                         i_size_write(inode, actual_end);
1704                         btrfs_ordered_update_i_size(inode, actual_end, NULL);
1705                 }
1706                 free_extent_map(em);
1707
1708                 cur_offset = last_byte;
1709                 if (cur_offset >= alloc_end) {
1710                         ret = 0;
1711                         break;
1712                 }
1713         }
1714         unlock_extent_cached(&BTRFS_I(inode)->io_tree, alloc_start, locked_end,
1715                              &cached_state, GFP_NOFS);
1716 out:
1717         mutex_unlock(&inode->i_mutex);
1718         return ret;
1719 }
1720
1721 static int find_desired_extent(struct inode *inode, loff_t *offset, int origin)
1722 {
1723         struct btrfs_root *root = BTRFS_I(inode)->root;
1724         struct extent_map *em;
1725         struct extent_state *cached_state = NULL;
1726         u64 lockstart = *offset;
1727         u64 lockend = i_size_read(inode);
1728         u64 start = *offset;
1729         u64 orig_start = *offset;
1730         u64 len = i_size_read(inode);
1731         u64 last_end = 0;
1732         int ret = 0;
1733
1734         lockend = max_t(u64, root->sectorsize, lockend);
1735         if (lockend <= lockstart)
1736                 lockend = lockstart + root->sectorsize;
1737
1738         len = lockend - lockstart + 1;
1739
1740         len = max_t(u64, len, root->sectorsize);
1741         if (inode->i_size == 0)
1742                 return -ENXIO;
1743
1744         lock_extent_bits(&BTRFS_I(inode)->io_tree, lockstart, lockend, 0,
1745                          &cached_state, GFP_NOFS);
1746
1747         /*
1748          * Delalloc is such a pain.  If we have a hole and we have pending
1749          * delalloc for a portion of the hole we will get back a hole that
1750          * exists for the entire range since it hasn't been actually written
1751          * yet.  So to take care of this case we need to look for an extent just
1752          * before the position we want in case there is outstanding delalloc
1753          * going on here.
1754          */
1755         if (origin == SEEK_HOLE && start != 0) {
1756                 if (start <= root->sectorsize)
1757                         em = btrfs_get_extent_fiemap(inode, NULL, 0, 0,
1758                                                      root->sectorsize, 0);
1759                 else
1760                         em = btrfs_get_extent_fiemap(inode, NULL, 0,
1761                                                      start - root->sectorsize,
1762                                                      root->sectorsize, 0);
1763                 if (IS_ERR(em)) {
1764                         ret = -ENXIO;
1765                         goto out;
1766                 }
1767                 last_end = em->start + em->len;
1768                 if (em->block_start == EXTENT_MAP_DELALLOC)
1769                         last_end = min_t(u64, last_end, inode->i_size);
1770                 free_extent_map(em);
1771         }
1772
1773         while (1) {
1774                 em = btrfs_get_extent_fiemap(inode, NULL, 0, start, len, 0);
1775                 if (IS_ERR(em)) {
1776                         ret = -ENXIO;
1777                         break;
1778                 }
1779
1780                 if (em->block_start == EXTENT_MAP_HOLE) {
1781                         if (test_bit(EXTENT_FLAG_VACANCY, &em->flags)) {
1782                                 if (last_end <= orig_start) {
1783                                         free_extent_map(em);
1784                                         ret = -ENXIO;
1785                                         break;
1786                                 }
1787                         }
1788
1789                         if (origin == SEEK_HOLE) {
1790                                 *offset = start;
1791                                 free_extent_map(em);
1792                                 break;
1793                         }
1794                 } else {
1795                         if (origin == SEEK_DATA) {
1796                                 if (em->block_start == EXTENT_MAP_DELALLOC) {
1797                                         if (start >= inode->i_size) {
1798                                                 free_extent_map(em);
1799                                                 ret = -ENXIO;
1800                                                 break;
1801                                         }
1802                                 }
1803
1804                                 *offset = start;
1805                                 free_extent_map(em);
1806                                 break;
1807                         }
1808                 }
1809
1810                 start = em->start + em->len;
1811                 last_end = em->start + em->len;
1812
1813                 if (em->block_start == EXTENT_MAP_DELALLOC)
1814                         last_end = min_t(u64, last_end, inode->i_size);
1815
1816                 if (test_bit(EXTENT_FLAG_VACANCY, &em->flags)) {
1817                         free_extent_map(em);
1818                         ret = -ENXIO;
1819                         break;
1820                 }
1821                 free_extent_map(em);
1822                 cond_resched();
1823         }
1824         if (!ret)
1825                 *offset = min(*offset, inode->i_size);
1826 out:
1827         unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
1828                              &cached_state, GFP_NOFS);
1829         return ret;
1830 }
1831
1832 static loff_t btrfs_file_llseek(struct file *file, loff_t offset, int origin)
1833 {
1834         struct inode *inode = file->f_mapping->host;
1835         int ret;
1836
1837         mutex_lock(&inode->i_mutex);
1838         switch (origin) {
1839         case SEEK_END:
1840         case SEEK_CUR:
1841                 offset = generic_file_llseek(file, offset, origin);
1842                 goto out;
1843         case SEEK_DATA:
1844         case SEEK_HOLE:
1845                 if (offset >= i_size_read(inode)) {
1846                         mutex_unlock(&inode->i_mutex);
1847                         return -ENXIO;
1848                 }
1849
1850                 ret = find_desired_extent(inode, &offset, origin);
1851                 if (ret) {
1852                         mutex_unlock(&inode->i_mutex);
1853                         return ret;
1854                 }
1855         }
1856
1857         if (offset < 0 && !(file->f_mode & FMODE_UNSIGNED_OFFSET)) {
1858                 offset = -EINVAL;
1859                 goto out;
1860         }
1861         if (offset > inode->i_sb->s_maxbytes) {
1862                 offset = -EINVAL;
1863                 goto out;
1864         }
1865
1866         /* Special lock needed here? */
1867         if (offset != file->f_pos) {
1868                 file->f_pos = offset;
1869                 file->f_version = 0;
1870         }
1871 out:
1872         mutex_unlock(&inode->i_mutex);
1873         return offset;
1874 }
1875
1876 const struct file_operations btrfs_file_operations = {
1877         .llseek         = btrfs_file_llseek,
1878         .read           = do_sync_read,
1879         .write          = do_sync_write,
1880         .aio_read       = generic_file_aio_read,
1881         .splice_read    = generic_file_splice_read,
1882         .aio_write      = btrfs_file_aio_write,
1883         .mmap           = btrfs_file_mmap,
1884         .open           = generic_file_open,
1885         .release        = btrfs_release_file,
1886         .fsync          = btrfs_sync_file,
1887         .fallocate      = btrfs_fallocate,
1888         .unlocked_ioctl = btrfs_ioctl,
1889 #ifdef CONFIG_COMPAT
1890         .compat_ioctl   = btrfs_ioctl,
1891 #endif
1892 };