fs/btrfs/file.c

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