SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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 "ctree.h"
  32 #include "disk-io.h"
  33 #include "transaction.h"
  34 #include "btrfs_inode.h"
  35 #include "ioctl.h"
  36 #include "print-tree.h"
  37 #include "tree-log.h"
  38 #include "locking.h"
  39 #include "compat.h"
  40
  41
  42 /* simple helper to fault in pages and copy.  This should go away
  43  * and be replaced with calls into generic code.
  44  */
  45 static noinline int btrfs_copy_from_user(loff_t pos, int num_pages,
  46                                          int write_bytes,
  47                                          struct page **prepared_pages,
  48                                          const char __user *buf)
  49 {
  50         long page_fault = 0;
  51         int i;
  52         int offset = pos & (PAGE_CACHE_SIZE - 1);
  53
  54         for (i = 0; i < num_pages && write_bytes > 0; i++, offset = 0) {
  55                 size_t count = min_t(size_t,
  56                                      PAGE_CACHE_SIZE - offset, write_bytes);
  57                 struct page *page = prepared_pages[i];
  58                 fault_in_pages_readable(buf, count);
  59
  60                 /* Copy data from userspace to the current page */
  61                 kmap(page);
  62                 page_fault = __copy_from_user(page_address(page) + offset,
  63                                               buf, count);
  64                 /* Flush processor's dcache for this page */
  65                 flush_dcache_page(page);
  66                 kunmap(page);
  67                 buf += count;
  68                 write_bytes -= count;
  69
  70                 if (page_fault)
  71                         break;
  72         }
  73         return page_fault ? -EFAULT : 0;
  74 }
  75
  76 /*
  77  * unlocks pages after btrfs_file_write is done with them
  78  */
  79 static noinline void btrfs_drop_pages(struct page **pages, size_t num_pages)
  80 {
  81         size_t i;
  82         for (i = 0; i < num_pages; i++) {
  83                 if (!pages[i])
  84                         break;
  85                 /* page checked is some magic around finding pages that
  86                  * have been modified without going through btrfs_set_page_dirty
  87                  * clear it here
  88                  */
  89                 ClearPageChecked(pages[i]);
  90                 unlock_page(pages[i]);
  91                 mark_page_accessed(pages[i]);
  92                 page_cache_release(pages[i]);
  93         }
  94 }
  95
  96 /*
  97  * after copy_from_user, pages need to be dirtied and we need to make
  98  * sure holes are created between the current EOF and the start of
  99  * any next extents (if required).
 100  *
 101  * this also makes the decision about creating an inline extent vs
 102  * doing real data extents, marking pages dirty and delalloc as required.
 103  */
 104 static noinline int dirty_and_release_pages(struct btrfs_trans_handle *trans,
 105                                    struct btrfs_root *root,
 106                                    struct file *file,
 107                                    struct page **pages,
 108                                    size_t num_pages,
 109                                    loff_t pos,
 110                                    size_t write_bytes)
 111 {
 112         int err = 0;
 113         int i;
 114         struct inode *inode = fdentry(file)->d_inode;
 115         u64 num_bytes;
 116         u64 start_pos;
 117         u64 end_of_last_block;
 118         u64 end_pos = pos + write_bytes;
 119         loff_t isize = i_size_read(inode);
 120
 121         start_pos = pos & ~((u64)root->sectorsize - 1);
 122         num_bytes = (write_bytes + pos - start_pos +
 123                     root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
 124
 125         end_of_last_block = start_pos + num_bytes - 1;
 126         err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block);
 127         if (err)
 128                 return err;
 129
 130         for (i = 0; i < num_pages; i++) {
 131                 struct page *p = pages[i];
 132                 SetPageUptodate(p);
 133                 ClearPageChecked(p);
 134                 set_page_dirty(p);
 135         }
 136         if (end_pos > isize) {
 137                 i_size_write(inode, end_pos);
 138                 /* we've only changed i_size in ram, and we haven't updated
 139                  * the disk i_size.  There is no need to log the inode
 140                  * at this time.
 141                  */
 142         }
 143         return err;
 144 }
 145
 146 /*
 147  * this drops all the extents in the cache that intersect the range
 148  * [start, end].  Existing extents are split as required.
 149  */
 150 int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
 151                             int skip_pinned)
 152 {
 153         struct extent_map *em;
 154         struct extent_map *split = NULL;
 155         struct extent_map *split2 = NULL;
 156         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
 157         u64 len = end - start + 1;
 158         int ret;
 159         int testend = 1;
 160         unsigned long flags;
 161         int compressed = 0;
 162
 163         WARN_ON(end < start);
 164         if (end == (u64)-1) {
 165                 len = (u64)-1;
 166                 testend = 0;
 167         }
 168         while (1) {
 169                 if (!split)
 170                         split = alloc_extent_map(GFP_NOFS);
 171                 if (!split2)
 172                         split2 = alloc_extent_map(GFP_NOFS);
 173
 174                 write_lock(&em_tree->lock);
 175                 em = lookup_extent_mapping(em_tree, start, len);
 176                 if (!em) {
 177                         write_unlock(&em_tree->lock);
 178                         break;
 179                 }
 180                 flags = em->flags;
 181                 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
 182                         if (em->start <= start &&
 183                             (!testend || em->start + em->len >= start + len)) {
 184                                 free_extent_map(em);
 185                                 write_unlock(&em_tree->lock);
 186                                 break;
 187                         }
 188                         if (start < em->start) {
 189                                 len = em->start - start;
 190                         } else {
 191                                 len = start + len - (em->start + em->len);
 192                                 start = em->start + em->len;
 193                         }
 194                         free_extent_map(em);
 195                         write_unlock(&em_tree->lock);
 196                         continue;
 197                 }
 198                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 199                 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
 200                 remove_extent_mapping(em_tree, em);
 201
 202                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 203                     em->start < start) {
 204                         split->start = em->start;
 205                         split->len = start - em->start;
 206                         split->orig_start = em->orig_start;
 207                         split->block_start = em->block_start;
 208
 209                         if (compressed)
 210                                 split->block_len = em->block_len;
 211                         else
 212                                 split->block_len = split->len;
 213
 214                         split->bdev = em->bdev;
 215                         split->flags = flags;
 216                         ret = add_extent_mapping(em_tree, split);
 217                         BUG_ON(ret);
 218                         free_extent_map(split);
 219                         split = split2;
 220                         split2 = NULL;
 221                 }
 222                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 223                     testend && em->start + em->len > start + len) {
 224                         u64 diff = start + len - em->start;
 225
 226                         split->start = start + len;
 227                         split->len = em->start + em->len - (start + len);
 228                         split->bdev = em->bdev;
 229                         split->flags = flags;
 230
 231                         if (compressed) {
 232                                 split->block_len = em->block_len;
 233                                 split->block_start = em->block_start;
 234                                 split->orig_start = em->orig_start;
 235                         } else {
 236                                 split->block_len = split->len;
 237                                 split->block_start = em->block_start + diff;
 238                                 split->orig_start = split->start;
 239                         }
 240
 241                         ret = add_extent_mapping(em_tree, split);
 242                         BUG_ON(ret);
 243                         free_extent_map(split);
 244                         split = NULL;
 245                 }
 246                 write_unlock(&em_tree->lock);
 247
 248                 /* once for us */
 249                 free_extent_map(em);
 250                 /* once for the tree*/
 251                 free_extent_map(em);
 252         }
 253         if (split)
 254                 free_extent_map(split);
 255         if (split2)
 256                 free_extent_map(split2);
 257         return 0;
 258 }
 259
 260 /*
 261  * this is very complex, but the basic idea is to drop all extents
 262  * in the range start - end.  hint_block is filled in with a block number
 263  * that would be a good hint to the block allocator for this file.
 264  *
 265  * If an extent intersects the range but is not entirely inside the range
 266  * it is either truncated or split.  Anything entirely inside the range
 267  * is deleted from the tree.
 268  *
 269  * inline_limit is used to tell this code which offsets in the file to keep
 270  * if they contain inline extents.
 271  */
 272 noinline int btrfs_drop_extents(struct btrfs_trans_handle *trans,
 273                        struct btrfs_root *root, struct inode *inode,
 274                        u64 start, u64 end, u64 locked_end,
 275                        u64 inline_limit, u64 *hint_byte, int drop_cache)
 276 {
 277         u64 extent_end = 0;
 278         u64 search_start = start;
 279         u64 ram_bytes = 0;
 280         u64 disk_bytenr = 0;
 281         u64 orig_locked_end = locked_end;
 282         u8 compression;
 283         u8 encryption;
 284         u16 other_encoding = 0;
 285         struct extent_buffer *leaf;
 286         struct btrfs_file_extent_item *extent;
 287         struct btrfs_path *path;
 288         struct btrfs_key key;
 289         struct btrfs_file_extent_item old;
 290         int keep;
 291         int slot;
 292         int bookend;
 293         int found_type = 0;
 294         int found_extent;
 295         int found_inline;
 296         int recow;
 297         int ret;
 298
 299         inline_limit = 0;
 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         while (1) {
 307                 recow = 0;
 308                 btrfs_release_path(root, path);
 309                 ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
 310                                                search_start, -1);
 311                 if (ret < 0)
 312                         goto out;
 313                 if (ret > 0) {
 314                         if (path->slots[0] == 0) {
 315                                 ret = 0;
 316                                 goto out;
 317                         }
 318                         path->slots[0]--;
 319                 }
 320 next_slot:
 321                 keep = 0;
 322                 bookend = 0;
 323                 found_extent = 0;
 324                 found_inline = 0;
 325                 compression = 0;
 326                 encryption = 0;
 327                 extent = NULL;
 328                 leaf = path->nodes[0];
 329                 slot = path->slots[0];
 330                 ret = 0;
 331                 btrfs_item_key_to_cpu(leaf, &key, slot);
 332                 if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY &&
 333                     key.offset >= end) {
 334                         goto out;
 335                 }
 336                 if (btrfs_key_type(&key) > BTRFS_EXTENT_DATA_KEY ||
 337                     key.objectid != inode->i_ino) {
 338                         goto out;
 339                 }
 340                 if (recow) {
 341                         search_start = max(key.offset, start);
 342                         continue;
 343                 }
 344                 if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY) {
 345                         extent = btrfs_item_ptr(leaf, slot,
 346                                                 struct btrfs_file_extent_item);
 347                         found_type = btrfs_file_extent_type(leaf, extent);
 348                         compression = btrfs_file_extent_compression(leaf,
 349                                                                     extent);
 350                         encryption = btrfs_file_extent_encryption(leaf,
 351                                                                   extent);
 352                         other_encoding = btrfs_file_extent_other_encoding(leaf,
 353                                                                   extent);
 354                         if (found_type == BTRFS_FILE_EXTENT_REG ||
 355                             found_type == BTRFS_FILE_EXTENT_PREALLOC) {
 356                                 extent_end =
 357                                      btrfs_file_extent_disk_bytenr(leaf,
 358                                                                    extent);
 359                                 if (extent_end)
 360                                         *hint_byte = extent_end;
 361
 362                                 extent_end = key.offset +
 363                                      btrfs_file_extent_num_bytes(leaf, extent);
 364                                 ram_bytes = btrfs_file_extent_ram_bytes(leaf,
 365                                                                 extent);
 366                                 found_extent = 1;
 367                         } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
 368                                 found_inline = 1;
 369                                 extent_end = key.offset +
 370                                      btrfs_file_extent_inline_len(leaf, extent);
 371                         }
 372                 } else {
 373                         extent_end = search_start;
 374                 }
 375
 376                 /* we found nothing we can drop */
 377                 if ((!found_extent && !found_inline) ||
 378                     search_start >= extent_end) {
 379                         int nextret;
 380                         u32 nritems;
 381                         nritems = btrfs_header_nritems(leaf);
 382                         if (slot >= nritems - 1) {
 383                                 nextret = btrfs_next_leaf(root, path);
 384                                 if (nextret)
 385                                         goto out;
 386                                 recow = 1;
 387                         } else {
 388                                 path->slots[0]++;
 389                         }
 390                         goto next_slot;
 391                 }
 392
 393                 if (end <= extent_end && start >= key.offset && found_inline)
 394                         *hint_byte = EXTENT_MAP_INLINE;
 395
 396                 if (found_extent) {
 397                         read_extent_buffer(leaf, &old, (unsigned long)extent,
 398                                            sizeof(old));
 399                 }
 400
 401                 if (end < extent_end && end >= key.offset) {
 402                         bookend = 1;
 403                         if (found_inline && start <= key.offset)
 404                                 keep = 1;
 405                 }
 406
 407                 if (bookend && found_extent) {
 408                         if (locked_end < extent_end) {
 409                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
 410                                                 locked_end, extent_end - 1,
 411                                                 GFP_NOFS);
 412                                 if (!ret) {
 413                                         btrfs_release_path(root, path);
 414                                         lock_extent(&BTRFS_I(inode)->io_tree,
 415                                                 locked_end, extent_end - 1,
 416                                                 GFP_NOFS);
 417                                         locked_end = extent_end;
 418                                         continue;
 419                                 }
 420                                 locked_end = extent_end;
 421                         }
 422                         disk_bytenr = le64_to_cpu(old.disk_bytenr);
 423                         if (disk_bytenr != 0) {
 424                                 ret = btrfs_inc_extent_ref(trans, root,
 425                                            disk_bytenr,
 426                                            le64_to_cpu(old.disk_num_bytes), 0,
 427                                            root->root_key.objectid,
 428                                            key.objectid, key.offset -
 429                                            le64_to_cpu(old.offset));
 430                                 BUG_ON(ret);
 431                         }
 432                 }
 433
 434                 if (found_inline) {
 435                         u64 mask = root->sectorsize - 1;
 436                         search_start = (extent_end + mask) & ~mask;
 437                 } else
 438                         search_start = extent_end;
 439
 440                 /* truncate existing extent */
 441                 if (start > key.offset) {
 442                         u64 new_num;
 443                         u64 old_num;
 444                         keep = 1;
 445                         WARN_ON(start & (root->sectorsize - 1));
 446                         if (found_extent) {
 447                                 new_num = start - key.offset;
 448                                 old_num = btrfs_file_extent_num_bytes(leaf,
 449                                                                       extent);
 450                                 *hint_byte =
 451                                         btrfs_file_extent_disk_bytenr(leaf,
 452                                                                       extent);
 453                                 if (btrfs_file_extent_disk_bytenr(leaf,
 454                                                                   extent)) {
 455                                         inode_sub_bytes(inode, old_num -
 456                                                         new_num);
 457                                 }
 458                                 btrfs_set_file_extent_num_bytes(leaf,
 459                                                         extent, new_num);
 460                                 btrfs_mark_buffer_dirty(leaf);
 461                         } else if (key.offset < inline_limit &&
 462                                    (end > extent_end) &&
 463                                    (inline_limit < extent_end)) {
 464                                 u32 new_size;
 465                                 new_size = btrfs_file_extent_calc_inline_size(
 466                                                    inline_limit - key.offset);
 467                                 inode_sub_bytes(inode, extent_end -
 468                                                 inline_limit);
 469                                 btrfs_set_file_extent_ram_bytes(leaf, extent,
 470                                                         new_size);
 471                                 if (!compression && !encryption) {
 472                                         btrfs_truncate_item(trans, root, path,
 473                                                             new_size, 1);
 474                                 }
 475                         }
 476                 }
 477                 /* delete the entire extent */
 478                 if (!keep) {
 479                         if (found_inline)
 480                                 inode_sub_bytes(inode, extent_end -
 481                                                 key.offset);
 482                         ret = btrfs_del_item(trans, root, path);
 483                         /* TODO update progress marker and return */
 484                         BUG_ON(ret);
 485                         extent = NULL;
 486                         btrfs_release_path(root, path);
 487                         /* the extent will be freed later */
 488                 }
 489                 if (bookend && found_inline && start <= key.offset) {
 490                         u32 new_size;
 491                         new_size = btrfs_file_extent_calc_inline_size(
 492                                                    extent_end - end);
 493                         inode_sub_bytes(inode, end - key.offset);
 494                         btrfs_set_file_extent_ram_bytes(leaf, extent,
 495                                                         new_size);
 496                         if (!compression && !encryption)
 497                                 ret = btrfs_truncate_item(trans, root, path,
 498                                                           new_size, 0);
 499                         BUG_ON(ret);
 500                 }
 501                 /* create bookend, splitting the extent in two */
 502                 if (bookend && found_extent) {
 503                         struct btrfs_key ins;
 504                         ins.objectid = inode->i_ino;
 505                         ins.offset = end;
 506                         btrfs_set_key_type(&ins, BTRFS_EXTENT_DATA_KEY);
 507
 508                         btrfs_release_path(root, path);
 509                         path->leave_spinning = 1;
 510                         ret = btrfs_insert_empty_item(trans, root, path, &ins,
 511                                                       sizeof(*extent));
 512                         BUG_ON(ret);
 513
 514                         leaf = path->nodes[0];
 515                         extent = btrfs_item_ptr(leaf, path->slots[0],
 516                                                 struct btrfs_file_extent_item);
 517                         write_extent_buffer(leaf, &old,
 518                                             (unsigned long)extent, sizeof(old));
 519
 520                         btrfs_set_file_extent_compression(leaf, extent,
 521                                                           compression);
 522                         btrfs_set_file_extent_encryption(leaf, extent,
 523                                                          encryption);
 524                         btrfs_set_file_extent_other_encoding(leaf, extent,
 525                                                              other_encoding);
 526                         btrfs_set_file_extent_offset(leaf, extent,
 527                                     le64_to_cpu(old.offset) + end - key.offset);
 528                         WARN_ON(le64_to_cpu(old.num_bytes) <
 529                                 (extent_end - end));
 530                         btrfs_set_file_extent_num_bytes(leaf, extent,
 531                                                         extent_end - end);
 532
 533                         /*
 534                          * set the ram bytes to the size of the full extent
 535                          * before splitting.  This is a worst case flag,
 536                          * but its the best we can do because we don't know
 537                          * how splitting affects compression
 538                          */
 539                         btrfs_set_file_extent_ram_bytes(leaf, extent,
 540                                                         ram_bytes);
 541                         btrfs_set_file_extent_type(leaf, extent, found_type);
 542
 543                         btrfs_unlock_up_safe(path, 1);
 544                         btrfs_mark_buffer_dirty(path->nodes[0]);
 545                         btrfs_set_lock_blocking(path->nodes[0]);
 546
 547                         path->leave_spinning = 0;
 548                         btrfs_release_path(root, path);
 549                         if (disk_bytenr != 0)
 550                                 inode_add_bytes(inode, extent_end - end);
 551                 }
 552
 553                 if (found_extent && !keep) {
 554                         u64 old_disk_bytenr = le64_to_cpu(old.disk_bytenr);
 555
 556                         if (old_disk_bytenr != 0) {
 557                                 inode_sub_bytes(inode,
 558                                                 le64_to_cpu(old.num_bytes));
 559                                 ret = btrfs_free_extent(trans, root,
 560                                                 old_disk_bytenr,
 561                                                 le64_to_cpu(old.disk_num_bytes),
 562                                                 0, root->root_key.objectid,
 563                                                 key.objectid, key.offset -
 564                                                 le64_to_cpu(old.offset));
 565                                 BUG_ON(ret);
 566                                 *hint_byte = old_disk_bytenr;
 567                         }
 568                 }
 569
 570                 if (search_start >= end) {
 571                         ret = 0;
 572                         goto out;
 573                 }
 574         }
 575 out:
 576         btrfs_free_path(path);
 577         if (locked_end > orig_locked_end) {
 578                 unlock_extent(&BTRFS_I(inode)->io_tree, orig_locked_end,
 579                               locked_end - 1, GFP_NOFS);
 580         }
 581         return ret;
 582 }
 583
 584 static int extent_mergeable(struct extent_buffer *leaf, int slot,
 585                             u64 objectid, u64 bytenr, u64 *start, u64 *end)
 586 {
 587         struct btrfs_file_extent_item *fi;
 588         struct btrfs_key key;
 589         u64 extent_end;
 590
 591         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
 592                 return 0;
 593
 594         btrfs_item_key_to_cpu(leaf, &key, slot);
 595         if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
 596                 return 0;
 597
 598         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
 599         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
 600             btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
 601             btrfs_file_extent_compression(leaf, fi) ||
 602             btrfs_file_extent_encryption(leaf, fi) ||
 603             btrfs_file_extent_other_encoding(leaf, fi))
 604                 return 0;
 605
 606         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 607         if ((*start && *start != key.offset) || (*end && *end != extent_end))
 608                 return 0;
 609
 610         *start = key.offset;
 611         *end = extent_end;
 612         return 1;
 613 }
 614
 615 /*
 616  * Mark extent in the range start - end as written.
 617  *
 618  * This changes extent type from 'pre-allocated' to 'regular'. If only
 619  * part of extent is marked as written, the extent will be split into
 620  * two or three.
 621  */
 622 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
 623                               struct btrfs_root *root,
 624                               struct inode *inode, u64 start, u64 end)
 625 {
 626         struct extent_buffer *leaf;
 627         struct btrfs_path *path;
 628         struct btrfs_file_extent_item *fi;
 629         struct btrfs_key key;
 630         u64 bytenr;
 631         u64 num_bytes;
 632         u64 extent_end;
 633         u64 orig_offset;
 634         u64 other_start;
 635         u64 other_end;
 636         u64 split = start;
 637         u64 locked_end = end;
 638         int extent_type;
 639         int split_end = 1;
 640         int ret;
 641
 642         btrfs_drop_extent_cache(inode, start, end - 1, 0);
 643
 644         path = btrfs_alloc_path();
 645         BUG_ON(!path);
 646 again:
 647         key.objectid = inode->i_ino;
 648         key.type = BTRFS_EXTENT_DATA_KEY;
 649         if (split == start)
 650                 key.offset = split;
 651         else
 652                 key.offset = split - 1;
 653
 654         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 655         if (ret > 0 && path->slots[0] > 0)
 656                 path->slots[0]--;
 657
 658         leaf = path->nodes[0];
 659         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 660         BUG_ON(key.objectid != inode->i_ino ||
 661                key.type != BTRFS_EXTENT_DATA_KEY);
 662         fi = btrfs_item_ptr(leaf, path->slots[0],
 663                             struct btrfs_file_extent_item);
 664         extent_type = btrfs_file_extent_type(leaf, fi);
 665         BUG_ON(extent_type != BTRFS_FILE_EXTENT_PREALLOC);
 666         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 667         BUG_ON(key.offset > start || extent_end < end);
 668
 669         bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 670         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
 671         orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
 672
 673         if (key.offset == start)
 674                 split = end;
 675
 676         if (key.offset == start && extent_end == end) {
 677                 int del_nr = 0;
 678                 int del_slot = 0;
 679                 other_start = end;
 680                 other_end = 0;
 681                 if (extent_mergeable(leaf, path->slots[0] + 1, inode->i_ino,
 682                                      bytenr, &other_start, &other_end)) {
 683                         extent_end = other_end;
 684                         del_slot = path->slots[0] + 1;
 685                         del_nr++;
 686                         ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
 687                                                 0, root->root_key.objectid,
 688                                                 inode->i_ino, orig_offset);
 689                         BUG_ON(ret);
 690                 }
 691                 other_start = 0;
 692                 other_end = start;
 693                 if (extent_mergeable(leaf, path->slots[0] - 1, inode->i_ino,
 694                                      bytenr, &other_start, &other_end)) {
 695                         key.offset = other_start;
 696                         del_slot = path->slots[0];
 697                         del_nr++;
 698                         ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
 699                                                 0, root->root_key.objectid,
 700                                                 inode->i_ino, orig_offset);
 701                         BUG_ON(ret);
 702                 }
 703                 split_end = 0;
 704                 if (del_nr == 0) {
 705                         btrfs_set_file_extent_type(leaf, fi,
 706                                                    BTRFS_FILE_EXTENT_REG);
 707                         goto done;
 708                 }
 709
 710                 fi = btrfs_item_ptr(leaf, del_slot - 1,
 711                                     struct btrfs_file_extent_item);
 712                 btrfs_set_file_extent_type(leaf, fi, BTRFS_FILE_EXTENT_REG);
 713                 btrfs_set_file_extent_num_bytes(leaf, fi,
 714                                                 extent_end - key.offset);
 715                 btrfs_mark_buffer_dirty(leaf);
 716
 717                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
 718                 BUG_ON(ret);
 719                 goto release;
 720         } else if (split == start) {
 721                 if (locked_end < extent_end) {
 722                         ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
 723                                         locked_end, extent_end - 1, GFP_NOFS);
 724                         if (!ret) {
 725                                 btrfs_release_path(root, path);
 726                                 lock_extent(&BTRFS_I(inode)->io_tree,
 727                                         locked_end, extent_end - 1, GFP_NOFS);
 728                                 locked_end = extent_end;
 729                                 goto again;
 730                         }
 731                         locked_end = extent_end;
 732                 }
 733                 btrfs_set_file_extent_num_bytes(leaf, fi, split - key.offset);
 734         } else  {
 735                 BUG_ON(key.offset != start);
 736                 key.offset = split;
 737                 btrfs_set_file_extent_offset(leaf, fi, key.offset -
 738                                              orig_offset);
 739                 btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - split);
 740                 btrfs_set_item_key_safe(trans, root, path, &key);
 741                 extent_end = split;
 742         }
 743
 744         if (extent_end == end) {
 745                 split_end = 0;
 746                 extent_type = BTRFS_FILE_EXTENT_REG;
 747         }
 748         if (extent_end == end && split == start) {
 749                 other_start = end;
 750                 other_end = 0;
 751                 if (extent_mergeable(leaf, path->slots[0] + 1, inode->i_ino,
 752                                      bytenr, &other_start, &other_end)) {
 753                         path->slots[0]++;
 754                         fi = btrfs_item_ptr(leaf, path->slots[0],
 755                                             struct btrfs_file_extent_item);
 756                         key.offset = split;
 757                         btrfs_set_item_key_safe(trans, root, path, &key);
 758                         btrfs_set_file_extent_offset(leaf, fi, key.offset -
 759                                                      orig_offset);
 760                         btrfs_set_file_extent_num_bytes(leaf, fi,
 761                                                         other_end - split);
 762                         goto done;
 763                 }
 764         }
 765         if (extent_end == end && split == end) {
 766                 other_start = 0;
 767                 other_end = start;
 768                 if (extent_mergeable(leaf, path->slots[0] - 1 , inode->i_ino,
 769                                      bytenr, &other_start, &other_end)) {
 770                         path->slots[0]--;
 771                         fi = btrfs_item_ptr(leaf, path->slots[0],
 772                                             struct btrfs_file_extent_item);
 773                         btrfs_set_file_extent_num_bytes(leaf, fi, extent_end -
 774                                                         other_start);
 775                         goto done;
 776                 }
 777         }
 778
 779         btrfs_mark_buffer_dirty(leaf);
 780
 781         ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
 782                                    root->root_key.objectid,
 783                                    inode->i_ino, orig_offset);
 784         BUG_ON(ret);
 785         btrfs_release_path(root, path);
 786
 787         key.offset = start;
 788         ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*fi));
 789         BUG_ON(ret);
 790
 791         leaf = path->nodes[0];
 792         fi = btrfs_item_ptr(leaf, path->slots[0],
 793                             struct btrfs_file_extent_item);
 794         btrfs_set_file_extent_generation(leaf, fi, trans->transid);
 795         btrfs_set_file_extent_type(leaf, fi, extent_type);
 796         btrfs_set_file_extent_disk_bytenr(leaf, fi, bytenr);
 797         btrfs_set_file_extent_disk_num_bytes(leaf, fi, num_bytes);
 798         btrfs_set_file_extent_offset(leaf, fi, key.offset - orig_offset);
 799         btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - key.offset);
 800         btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
 801         btrfs_set_file_extent_compression(leaf, fi, 0);
 802         btrfs_set_file_extent_encryption(leaf, fi, 0);
 803         btrfs_set_file_extent_other_encoding(leaf, fi, 0);
 804 done:
 805         btrfs_mark_buffer_dirty(leaf);
 806
 807 release:
 808         btrfs_release_path(root, path);
 809         if (split_end && split == start) {
 810                 split = end;
 811                 goto again;
 812         }
 813         if (locked_end > end) {
 814                 unlock_extent(&BTRFS_I(inode)->io_tree, end, locked_end - 1,
 815                               GFP_NOFS);
 816         }
 817         btrfs_free_path(path);
 818         return 0;
 819 }
 820
 821 /*
 822  * this gets pages into the page cache and locks them down, it also properly
 823  * waits for data=ordered extents to finish before allowing the pages to be
 824  * modified.
 825  */
 826 static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
 827                          struct page **pages, size_t num_pages,
 828                          loff_t pos, unsigned long first_index,
 829                          unsigned long last_index, size_t write_bytes)
 830 {
 831         int i;
 832         unsigned long index = pos >> PAGE_CACHE_SHIFT;
 833         struct inode *inode = fdentry(file)->d_inode;
 834         int err = 0;
 835         u64 start_pos;
 836         u64 last_pos;
 837
 838         start_pos = pos & ~((u64)root->sectorsize - 1);
 839         last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
 840
 841         if (start_pos > inode->i_size) {
 842                 err = btrfs_cont_expand(inode, start_pos);
 843                 if (err)
 844                         return err;
 845         }
 846
 847         memset(pages, 0, num_pages * sizeof(struct page *));
 848 again:
 849         for (i = 0; i < num_pages; i++) {
 850                 pages[i] = grab_cache_page(inode->i_mapping, index + i);
 851                 if (!pages[i]) {
 852                         err = -ENOMEM;
 853                         BUG_ON(1);
 854                 }
 855                 wait_on_page_writeback(pages[i]);
 856         }
 857         if (start_pos < inode->i_size) {
 858                 struct btrfs_ordered_extent *ordered;
 859                 lock_extent(&BTRFS_I(inode)->io_tree,
 860                             start_pos, last_pos - 1, GFP_NOFS);
 861                 ordered = btrfs_lookup_first_ordered_extent(inode,
 862                                                             last_pos - 1);
 863                 if (ordered &&
 864                     ordered->file_offset + ordered->len > start_pos &&
 865                     ordered->file_offset < last_pos) {
 866                         btrfs_put_ordered_extent(ordered);
 867                         unlock_extent(&BTRFS_I(inode)->io_tree,
 868                                       start_pos, last_pos - 1, GFP_NOFS);
 869                         for (i = 0; i < num_pages; i++) {
 870                                 unlock_page(pages[i]);
 871                                 page_cache_release(pages[i]);
 872                         }
 873                         btrfs_wait_ordered_range(inode, start_pos,
 874                                                  last_pos - start_pos);
 875                         goto again;
 876                 }
 877                 if (ordered)
 878                         btrfs_put_ordered_extent(ordered);
 879
 880                 clear_extent_bits(&BTRFS_I(inode)->io_tree, start_pos,
 881                                   last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC |
 882                                   EXTENT_DO_ACCOUNTING,
 883                                   GFP_NOFS);
 884                 unlock_extent(&BTRFS_I(inode)->io_tree,
 885                               start_pos, last_pos - 1, GFP_NOFS);
 886         }
 887         for (i = 0; i < num_pages; i++) {
 888                 clear_page_dirty_for_io(pages[i]);
 889                 set_page_extent_mapped(pages[i]);
 890                 WARN_ON(!PageLocked(pages[i]));
 891         }
 892         return 0;
 893 }
 894
 895 static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
 896                                 size_t count, loff_t *ppos)
 897 {
 898         loff_t pos;
 899         loff_t start_pos;
 900         ssize_t num_written = 0;
 901         ssize_t err = 0;
 902         int ret = 0;
 903         struct inode *inode = fdentry(file)->d_inode;
 904         struct btrfs_root *root = BTRFS_I(inode)->root;
 905         struct page **pages = NULL;
 906         int nrptrs;
 907         struct page *pinned[2];
 908         unsigned long first_index;
 909         unsigned long last_index;
 910         int will_write;
 911
 912         will_write = ((file->f_flags & O_SYNC) || IS_SYNC(inode) ||
 913                       (file->f_flags & O_DIRECT));
 914
 915         nrptrs = min((count + PAGE_CACHE_SIZE - 1) / PAGE_CACHE_SIZE,
 916                      PAGE_CACHE_SIZE / (sizeof(struct page *)));
 917         pinned[0] = NULL;
 918         pinned[1] = NULL;
 919
 920         pos = *ppos;
 921         start_pos = pos;
 922
 923         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
 924
 925         /* do the reserve before the mutex lock in case we have to do some
 926          * flushing.  We wouldn't deadlock, but this is more polite.
 927          */
 928         err = btrfs_reserve_metadata_for_delalloc(root, inode, 1);
 929         if (err)
 930                 goto out_nolock;
 931
 932         mutex_lock(&inode->i_mutex);
 933
 934         current->backing_dev_info = inode->i_mapping->backing_dev_info;
 935         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
 936         if (err)
 937                 goto out;
 938
 939         if (count == 0)
 940                 goto out;
 941
 942         err = file_remove_suid(file);
 943         if (err)
 944                 goto out;
 945
 946         file_update_time(file);
 947
 948         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
 949
 950         /* generic_write_checks can change our pos */
 951         start_pos = pos;
 952
 953         BTRFS_I(inode)->sequence++;
 954         first_index = pos >> PAGE_CACHE_SHIFT;
 955         last_index = (pos + count) >> PAGE_CACHE_SHIFT;
 956
 957         /*
 958          * there are lots of better ways to do this, but this code
 959          * makes sure the first and last page in the file range are
 960          * up to date and ready for cow
 961          */
 962         if ((pos & (PAGE_CACHE_SIZE - 1))) {
 963                 pinned[0] = grab_cache_page(inode->i_mapping, first_index);
 964                 if (!PageUptodate(pinned[0])) {
 965                         ret = btrfs_readpage(NULL, pinned[0]);
 966                         BUG_ON(ret);
 967                         wait_on_page_locked(pinned[0]);
 968                 } else {
 969                         unlock_page(pinned[0]);
 970                 }
 971         }
 972         if ((pos + count) & (PAGE_CACHE_SIZE - 1)) {
 973                 pinned[1] = grab_cache_page(inode->i_mapping, last_index);
 974                 if (!PageUptodate(pinned[1])) {
 975                         ret = btrfs_readpage(NULL, pinned[1]);
 976                         BUG_ON(ret);
 977                         wait_on_page_locked(pinned[1]);
 978                 } else {
 979                         unlock_page(pinned[1]);
 980                 }
 981         }
 982
 983         while (count > 0) {
 984                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
 985                 size_t write_bytes = min(count, nrptrs *
 986                                         (size_t)PAGE_CACHE_SIZE -
 987                                          offset);
 988                 size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
 989                                         PAGE_CACHE_SHIFT;
 990
 991                 WARN_ON(num_pages > nrptrs);
 992                 memset(pages, 0, sizeof(struct page *) * nrptrs);
 993
 994                 ret = btrfs_check_data_free_space(root, inode, write_bytes);
 995                 if (ret)
 996                         goto out;
 997
 998                 ret = prepare_pages(root, file, pages, num_pages,
 999                                     pos, first_index, last_index,
1000                                     write_bytes);
1001                 if (ret) {
1002                         btrfs_free_reserved_data_space(root, inode,
1003                                                        write_bytes);
1004                         goto out;
1005                 }
1006
1007                 ret = btrfs_copy_from_user(pos, num_pages,
1008                                            write_bytes, pages, buf);
1009                 if (ret) {
1010                         btrfs_free_reserved_data_space(root, inode,
1011                                                        write_bytes);
1012                         btrfs_drop_pages(pages, num_pages);
1013                         goto out;
1014                 }
1015
1016                 ret = dirty_and_release_pages(NULL, root, file, pages,
1017                                               num_pages, pos, write_bytes);
1018                 btrfs_drop_pages(pages, num_pages);
1019                 if (ret) {
1020                         btrfs_free_reserved_data_space(root, inode,
1021                                                        write_bytes);
1022                         goto out;
1023                 }
1024
1025                 if (will_write) {
1026                         btrfs_fdatawrite_range(inode->i_mapping, pos,
1027                                                pos + write_bytes - 1,
1028                                                WB_SYNC_ALL);
1029                 } else {
1030                         balance_dirty_pages_ratelimited_nr(inode->i_mapping,
1031                                                            num_pages);
1032                         if (num_pages <
1033                             (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
1034                                 btrfs_btree_balance_dirty(root, 1);
1035                         btrfs_throttle(root);
1036                 }
1037
1038                 buf += write_bytes;
1039                 count -= write_bytes;
1040                 pos += write_bytes;
1041                 num_written += write_bytes;
1042
1043                 cond_resched();
1044         }
1045 out:
1046         mutex_unlock(&inode->i_mutex);
1047         if (ret)
1048                 err = ret;
1049         btrfs_unreserve_metadata_for_delalloc(root, inode, 1);
1050
1051 out_nolock:
1052         kfree(pages);
1053         if (pinned[0])
1054                 page_cache_release(pinned[0]);
1055         if (pinned[1])
1056                 page_cache_release(pinned[1]);
1057         *ppos = pos;
1058
1059         /*
1060          * we want to make sure fsync finds this change
1061          * but we haven't joined a transaction running right now.
1062          *
1063          * Later on, someone is sure to update the inode and get the
1064          * real transid recorded.
1065          *
1066          * We set last_trans now to the fs_info generation + 1,
1067          * this will either be one more than the running transaction
1068          * or the generation used for the next transaction if there isn't
1069          * one running right now.
1070          */
1071         BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
1072
1073         if (num_written > 0 && will_write) {
1074                 struct btrfs_trans_handle *trans;
1075
1076                 err = btrfs_wait_ordered_range(inode, start_pos, num_written);
1077                 if (err)
1078                         num_written = err;
1079
1080                 if ((file->f_flags & O_SYNC) || IS_SYNC(inode)) {
1081                         trans = btrfs_start_transaction(root, 1);
1082                         ret = btrfs_log_dentry_safe(trans, root,
1083                                                     file->f_dentry);
1084                         if (ret == 0) {
1085                                 ret = btrfs_sync_log(trans, root);
1086                                 if (ret == 0)
1087                                         btrfs_end_transaction(trans, root);
1088                                 else
1089                                         btrfs_commit_transaction(trans, root);
1090                         } else if (ret != BTRFS_NO_LOG_SYNC) {
1091                                 btrfs_commit_transaction(trans, root);
1092                         } else {
1093                                 btrfs_end_transaction(trans, root);
1094                         }
1095                 }
1096                 if (file->f_flags & O_DIRECT) {
1097                         invalidate_mapping_pages(inode->i_mapping,
1098                               start_pos >> PAGE_CACHE_SHIFT,
1099                              (start_pos + num_written - 1) >> PAGE_CACHE_SHIFT);
1100                 }
1101         }
1102         current->backing_dev_info = NULL;
1103         return num_written ? num_written : err;
1104 }
1105
1106 int btrfs_release_file(struct inode *inode, struct file *filp)
1107 {
1108         /*
1109          * ordered_data_close is set by settattr when we are about to truncate
1110          * a file from a non-zero size to a zero size.  This tries to
1111          * flush down new bytes that may have been written if the
1112          * application were using truncate to replace a file in place.
1113          */
1114         if (BTRFS_I(inode)->ordered_data_close) {
1115                 BTRFS_I(inode)->ordered_data_close = 0;
1116                 btrfs_add_ordered_operation(NULL, BTRFS_I(inode)->root, inode);
1117                 if (inode->i_size > BTRFS_ORDERED_OPERATIONS_FLUSH_LIMIT)
1118                         filemap_flush(inode->i_mapping);
1119         }
1120         if (filp->private_data)
1121                 btrfs_ioctl_trans_end(filp);
1122         return 0;
1123 }
1124
1125 /*
1126  * fsync call for both files and directories.  This logs the inode into
1127  * the tree log instead of forcing full commits whenever possible.
1128  *
1129  * It needs to call filemap_fdatawait so that all ordered extent updates are
1130  * in the metadata btree are up to date for copying to the log.
1131  *
1132  * It drops the inode mutex before doing the tree log commit.  This is an
1133  * important optimization for directories because holding the mutex prevents
1134  * new operations on the dir while we write to disk.
1135  */
1136 int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
1137 {
1138         struct inode *inode = dentry->d_inode;
1139         struct btrfs_root *root = BTRFS_I(inode)->root;
1140         int ret = 0;
1141         struct btrfs_trans_handle *trans;
1142
1143
1144         /* we wait first, since the writeback may change the inode */
1145         root->log_batch++;
1146         /* the VFS called filemap_fdatawrite for us */
1147         btrfs_wait_ordered_range(inode, 0, (u64)-1);
1148         root->log_batch++;
1149
1150         /*
1151          * check the transaction that last modified this inode
1152          * and see if its already been committed
1153          */
1154         if (!BTRFS_I(inode)->last_trans)
1155                 goto out;
1156
1157         /*
1158          * if the last transaction that changed this file was before
1159          * the current transaction, we can bail out now without any
1160          * syncing
1161          */
1162         mutex_lock(&root->fs_info->trans_mutex);
1163         if (BTRFS_I(inode)->last_trans <=
1164             root->fs_info->last_trans_committed) {
1165                 BTRFS_I(inode)->last_trans = 0;
1166                 mutex_unlock(&root->fs_info->trans_mutex);
1167                 goto out;
1168         }
1169         mutex_unlock(&root->fs_info->trans_mutex);
1170
1171         /*
1172          * ok we haven't committed the transaction yet, lets do a commit
1173          */
1174         if (file && file->private_data)
1175                 btrfs_ioctl_trans_end(file);
1176
1177         trans = btrfs_start_transaction(root, 1);
1178         if (!trans) {
1179                 ret = -ENOMEM;
1180                 goto out;
1181         }
1182
1183         ret = btrfs_log_dentry_safe(trans, root, dentry);
1184         if (ret < 0)
1185                 goto out;
1186
1187         /* we've logged all the items and now have a consistent
1188          * version of the file in the log.  It is possible that
1189          * someone will come in and modify the file, but that's
1190          * fine because the log is consistent on disk, and we
1191          * have references to all of the file's extents
1192          *
1193          * It is possible that someone will come in and log the
1194          * file again, but that will end up using the synchronization
1195          * inside btrfs_sync_log to keep things safe.
1196          */
1197         mutex_unlock(&dentry->d_inode->i_mutex);
1198
1199         if (ret != BTRFS_NO_LOG_SYNC) {
1200                 if (ret > 0) {
1201                         ret = btrfs_commit_transaction(trans, root);
1202                 } else {
1203                         ret = btrfs_sync_log(trans, root);
1204                         if (ret == 0)
1205                                 ret = btrfs_end_transaction(trans, root);
1206                         else
1207                                 ret = btrfs_commit_transaction(trans, root);
1208                 }
1209         } else {
1210                 ret = btrfs_end_transaction(trans, root);
1211         }
1212         mutex_lock(&dentry->d_inode->i_mutex);
1213 out:
1214         return ret > 0 ? EIO : ret;
1215 }
1216
1217 static struct vm_operations_struct btrfs_file_vm_ops = {
1218         .fault          = filemap_fault,
1219         .page_mkwrite   = btrfs_page_mkwrite,
1220 };
1221
1222 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
1223 {
1224         vma->vm_ops = &btrfs_file_vm_ops;
1225         file_accessed(filp);
1226         return 0;
1227 }
1228
1229 struct file_operations btrfs_file_operations = {
1230         .llseek         = generic_file_llseek,
1231         .read           = do_sync_read,
1232         .aio_read       = generic_file_aio_read,
1233         .splice_read    = generic_file_splice_read,
1234         .write          = btrfs_file_write,
1235         .mmap           = btrfs_file_mmap,
1236         .open           = generic_file_open,
1237         .release        = btrfs_release_file,
1238         .fsync          = btrfs_sync_file,
1239         .unlocked_ioctl = btrfs_ioctl,
1240 #ifdef CONFIG_COMPAT
1241         .compat_ioctl   = btrfs_ioctl,
1242 #endif
1243 };