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