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/module.h>
  20 #include <linux/buffer_head.h>
  21 #include <linux/fs.h>
  22 #include <linux/pagemap.h>
  23 #include <linux/highmem.h>
  24 #include <linux/time.h>
  25 #include <linux/init.h>
  26 #include <linux/string.h>
  27 #include <linux/smp_lock.h>
  28 #include <linux/backing-dev.h>
  29 #include <linux/mpage.h>
  30 #include <linux/swap.h>
  31 #include <linux/writeback.h>
  32 #include <linux/statfs.h>
  33 #include <linux/compat.h>
  34 #include "ctree.h"
  35 #include "disk-io.h"
  36 #include "transaction.h"
  37 #include "btrfs_inode.h"
  38 #include "ioctl.h"
  39 #include "print-tree.h"
  40
  41
  42 static int btrfs_copy_from_user(loff_t pos, int num_pages, int write_bytes,
  43                                 struct page **prepared_pages,
  44                                 const char __user * buf)
  45 {
  46         long page_fault = 0;
  47         int i;
  48         int offset = pos & (PAGE_CACHE_SIZE - 1);
  49
  50         for (i = 0; i < num_pages && write_bytes > 0; i++, offset = 0) {
  51                 size_t count = min_t(size_t,
  52                                      PAGE_CACHE_SIZE - offset, write_bytes);
  53                 struct page *page = prepared_pages[i];
  54                 fault_in_pages_readable(buf, count);
  55
  56                 /* Copy data from userspace to the current page */
  57                 kmap(page);
  58                 page_fault = __copy_from_user(page_address(page) + offset,
  59                                               buf, count);
  60                 /* Flush processor's dcache for this page */
  61                 flush_dcache_page(page);
  62                 kunmap(page);
  63                 buf += count;
  64                 write_bytes -= count;
  65
  66                 if (page_fault)
  67                         break;
  68         }
  69         return page_fault ? -EFAULT : 0;
  70 }
  71
  72 static void btrfs_drop_pages(struct page **pages, size_t num_pages)
  73 {
  74         size_t i;
  75         for (i = 0; i < num_pages; i++) {
  76                 if (!pages[i])
  77                         break;
  78                 unlock_page(pages[i]);
  79                 mark_page_accessed(pages[i]);
  80                 page_cache_release(pages[i]);
  81         }
  82 }
  83
  84 static int dirty_and_release_pages(struct btrfs_trans_handle *trans,
  85                                    struct btrfs_root *root,
  86                                    struct file *file,
  87                                    struct page **pages,
  88                                    size_t num_pages,
  89                                    loff_t pos,
  90                                    size_t write_bytes)
  91 {
  92         int i;
  93         int offset;
  94         int err = 0;
  95         int ret;
  96         int this_write;
  97         struct inode *inode = file->f_path.dentry->d_inode;
  98         struct buffer_head *bh;
  99         struct btrfs_file_extent_item *ei;
 100
 101         for (i = 0; i < num_pages; i++) {
 102                 offset = pos & (PAGE_CACHE_SIZE -1);
 103                 this_write = min((size_t)PAGE_CACHE_SIZE - offset, write_bytes);
 104                 /* FIXME, one block at a time */
 105
 106                 mutex_lock(&root->fs_info->fs_mutex);
 107                 trans = btrfs_start_transaction(root, 1);
 108                 btrfs_set_trans_block_group(trans, inode);
 109
 110                 bh = page_buffers(pages[i]);
 111
 112                 if (buffer_mapped(bh) && bh->b_blocknr == 0) {
 113                         struct btrfs_key key;
 114                         struct btrfs_path *path;
 115                         char *ptr;
 116                         u32 datasize;
 117
 118                         /* create an inline extent, and copy the data in */
 119                         path = btrfs_alloc_path();
 120                         BUG_ON(!path);
 121                         key.objectid = inode->i_ino;
 122                         key.offset = pages[i]->index << PAGE_CACHE_SHIFT;
 123                         key.flags = 0;
 124                         btrfs_set_key_type(&key, BTRFS_EXTENT_DATA_KEY);
 125                         BUG_ON(write_bytes >= PAGE_CACHE_SIZE);
 126                         datasize = offset +
 127                                 btrfs_file_extent_calc_inline_size(write_bytes);
 128
 129                         ret = btrfs_insert_empty_item(trans, root, path, &key,
 130                                                       datasize);
 131                         BUG_ON(ret);
 132                         ei = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]),
 133                                path->slots[0], struct btrfs_file_extent_item);
 134                         btrfs_set_file_extent_generation(ei, trans->transid);
 135                         btrfs_set_file_extent_type(ei,
 136                                                    BTRFS_FILE_EXTENT_INLINE);
 137                         ptr = btrfs_file_extent_inline_start(ei);
 138                         btrfs_memcpy(root, path->nodes[0]->b_data,
 139                                      ptr, bh->b_data, offset + write_bytes);
 140                         mark_buffer_dirty(path->nodes[0]);
 141                         btrfs_free_path(path);
 142                 } else if (buffer_mapped(bh)) {
 143                         /* csum the file data */
 144                         btrfs_csum_file_block(trans, root, inode->i_ino,
 145                                       pages[i]->index << PAGE_CACHE_SHIFT,
 146                                       kmap(pages[i]), PAGE_CACHE_SIZE);
 147                         kunmap(pages[i]);
 148                 }
 149                 SetPageChecked(pages[i]);
 150                 ret = btrfs_end_transaction(trans, root);
 151                 BUG_ON(ret);
 152                 mutex_unlock(&root->fs_info->fs_mutex);
 153
 154                 ret = btrfs_commit_write(file, pages[i], offset,
 155                                          offset + this_write);
 156                 pos += this_write;
 157                 if (ret) {
 158                         err = ret;
 159                         goto failed;
 160                 }
 161                 WARN_ON(this_write > write_bytes);
 162                 write_bytes -= this_write;
 163         }
 164 failed:
 165         return err;
 166 }
 167
 168 /*
 169  * this is very complex, but the basic idea is to drop all extents
 170  * in the range start - end.  hint_block is filled in with a block number
 171  * that would be a good hint to the block allocator for this file.
 172  *
 173  * If an extent intersects the range but is not entirely inside the range
 174  * it is either truncated or split.  Anything entirely inside the range
 175  * is deleted from the tree.
 176  */
 177 int btrfs_drop_extents(struct btrfs_trans_handle *trans,
 178                        struct btrfs_root *root, struct inode *inode,
 179                        u64 start, u64 end, u64 *hint_block)
 180 {
 181         int ret;
 182         struct btrfs_key key;
 183         struct btrfs_leaf *leaf;
 184         int slot;
 185         struct btrfs_file_extent_item *extent;
 186         u64 extent_end = 0;
 187         int keep;
 188         struct btrfs_file_extent_item old;
 189         struct btrfs_path *path;
 190         u64 search_start = start;
 191         int bookend;
 192         int found_type;
 193         int found_extent;
 194         int found_inline;
 195
 196         path = btrfs_alloc_path();
 197         if (!path)
 198                 return -ENOMEM;
 199         while(1) {
 200                 btrfs_release_path(root, path);
 201                 ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
 202                                                search_start, -1);
 203                 if (ret < 0)
 204                         goto out;
 205                 if (ret > 0) {
 206                         if (path->slots[0] == 0) {
 207                                 ret = 0;
 208                                 goto out;
 209                         }
 210                         path->slots[0]--;
 211                 }
 212                 keep = 0;
 213                 bookend = 0;
 214                 found_extent = 0;
 215                 found_inline = 0;
 216                 extent = NULL;
 217                 leaf = btrfs_buffer_leaf(path->nodes[0]);
 218                 slot = path->slots[0];
 219                 btrfs_disk_key_to_cpu(&key, &leaf->items[slot].key);
 220                 if (key.offset >= end || key.objectid != inode->i_ino) {
 221                         ret = 0;
 222                         goto out;
 223                 }
 224                 if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY) {
 225                         ret = 0;
 226                         goto out;
 227                 }
 228                 extent = btrfs_item_ptr(leaf, slot,
 229                                         struct btrfs_file_extent_item);
 230                 found_type = btrfs_file_extent_type(extent);
 231                 if (found_type == BTRFS_FILE_EXTENT_REG) {
 232                         extent_end = key.offset +
 233                                 (btrfs_file_extent_num_blocks(extent) <<
 234                                  inode->i_blkbits);
 235                         found_extent = 1;
 236                 } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
 237                         found_inline = 1;
 238                         extent_end = key.offset +
 239                              btrfs_file_extent_inline_len(leaf->items + slot);
 240                 }
 241
 242                 /* we found nothing we can drop */
 243                 if (!found_extent && !found_inline) {
 244                         ret = 0;
 245                         goto out;
 246                 }
 247
 248                 /* we found nothing inside the range */
 249                 if (search_start >= extent_end) {
 250                         ret = 0;
 251                         goto out;
 252                 }
 253
 254                 /* FIXME, there's only one inline extent allowed right now */
 255                 if (found_inline) {
 256                         u64 mask = root->blocksize - 1;
 257                         search_start = (extent_end + mask) & ~mask;
 258                 } else
 259                         search_start = extent_end;
 260
 261                 if (end < extent_end && end >= key.offset) {
 262                         if (found_extent) {
 263                                 u64 disk_blocknr =
 264                                         btrfs_file_extent_disk_blocknr(extent);
 265                                 u64 disk_num_blocks =
 266                                       btrfs_file_extent_disk_num_blocks(extent);
 267                                 memcpy(&old, extent, sizeof(old));
 268                                 if (disk_blocknr != 0) {
 269                                         ret = btrfs_inc_extent_ref(trans, root,
 270                                                  disk_blocknr, disk_num_blocks);
 271                                         BUG_ON(ret);
 272                                 }
 273                         }
 274                         WARN_ON(found_inline);
 275                         bookend = 1;
 276                 }
 277
 278                 /* truncate existing extent */
 279                 if (start > key.offset) {
 280                         u64 new_num;
 281                         u64 old_num;
 282                         keep = 1;
 283                         WARN_ON(start & (root->blocksize - 1));
 284                         if (found_extent) {
 285                                 new_num = (start - key.offset) >>
 286                                         inode->i_blkbits;
 287                                 old_num = btrfs_file_extent_num_blocks(extent);
 288                                 *hint_block =
 289                                         btrfs_file_extent_disk_blocknr(extent);
 290                                 if (btrfs_file_extent_disk_blocknr(extent)) {
 291                                         inode->i_blocks -=
 292                                                 (old_num - new_num) << 3;
 293                                 }
 294                                 btrfs_set_file_extent_num_blocks(extent,
 295                                                                  new_num);
 296                                 mark_buffer_dirty(path->nodes[0]);
 297                         } else {
 298                                 WARN_ON(1);
 299                         }
 300                 }
 301                 /* delete the entire extent */
 302                 if (!keep) {
 303                         u64 disk_blocknr = 0;
 304                         u64 disk_num_blocks = 0;
 305                         u64 extent_num_blocks = 0;
 306                         if (found_extent) {
 307                                 disk_blocknr =
 308                                       btrfs_file_extent_disk_blocknr(extent);
 309                                 disk_num_blocks =
 310                                       btrfs_file_extent_disk_num_blocks(extent);
 311                                 extent_num_blocks =
 312                                       btrfs_file_extent_num_blocks(extent);
 313                                 *hint_block =
 314                                         btrfs_file_extent_disk_blocknr(extent);
 315                         }
 316                         ret = btrfs_del_item(trans, root, path);
 317                         BUG_ON(ret);
 318                         btrfs_release_path(root, path);
 319                         extent = NULL;
 320                         if (found_extent && disk_blocknr != 0) {
 321                                 inode->i_blocks -= extent_num_blocks << 3;
 322                                 ret = btrfs_free_extent(trans, root,
 323                                                         disk_blocknr,
 324                                                         disk_num_blocks, 0);
 325                         }
 326
 327                         BUG_ON(ret);
 328                         if (!bookend && search_start >= end) {
 329                                 ret = 0;
 330                                 goto out;
 331                         }
 332                         if (!bookend)
 333                                 continue;
 334                 }
 335                 /* create bookend, splitting the extent in two */
 336                 if (bookend && found_extent) {
 337                         struct btrfs_key ins;
 338                         ins.objectid = inode->i_ino;
 339                         ins.offset = end;
 340                         ins.flags = 0;
 341                         btrfs_set_key_type(&ins, BTRFS_EXTENT_DATA_KEY);
 342
 343                         btrfs_release_path(root, path);
 344                         ret = btrfs_insert_empty_item(trans, root, path, &ins,
 345                                                       sizeof(*extent));
 346                         BUG_ON(ret);
 347                         extent = btrfs_item_ptr(
 348                                     btrfs_buffer_leaf(path->nodes[0]),
 349                                     path->slots[0],
 350                                     struct btrfs_file_extent_item);
 351                         btrfs_set_file_extent_disk_blocknr(extent,
 352                                     btrfs_file_extent_disk_blocknr(&old));
 353                         btrfs_set_file_extent_disk_num_blocks(extent,
 354                                     btrfs_file_extent_disk_num_blocks(&old));
 355
 356                         btrfs_set_file_extent_offset(extent,
 357                                     btrfs_file_extent_offset(&old) +
 358                                     ((end - key.offset) >> inode->i_blkbits));
 359                         WARN_ON(btrfs_file_extent_num_blocks(&old) <
 360                                 (extent_end - end) >> inode->i_blkbits);
 361                         btrfs_set_file_extent_num_blocks(extent,
 362                                     (extent_end - end) >> inode->i_blkbits);
 363
 364                         btrfs_set_file_extent_type(extent,
 365                                                    BTRFS_FILE_EXTENT_REG);
 366                         btrfs_set_file_extent_generation(extent,
 367                                     btrfs_file_extent_generation(&old));
 368                         btrfs_mark_buffer_dirty(path->nodes[0]);
 369                         if (btrfs_file_extent_disk_blocknr(&old) != 0) {
 370                                 inode->i_blocks +=
 371                                       btrfs_file_extent_num_blocks(extent) << 3;
 372                         }
 373                         ret = 0;
 374                         goto out;
 375                 }
 376         }
 377 out:
 378         btrfs_free_path(path);
 379         return ret;
 380 }
 381
 382 /*
 383  * this gets pages into the page cache and locks them down
 384  */
 385 static int prepare_pages(struct btrfs_root *root,
 386                          struct file *file,
 387                          struct page **pages,
 388                          size_t num_pages,
 389                          loff_t pos,
 390                          unsigned long first_index,
 391                          unsigned long last_index,
 392                          size_t write_bytes,
 393                          u64 alloc_extent_start)
 394 {
 395         int i;
 396         unsigned long index = pos >> PAGE_CACHE_SHIFT;
 397         struct inode *inode = file->f_path.dentry->d_inode;
 398         int offset;
 399         int err = 0;
 400         int this_write;
 401         struct buffer_head *bh;
 402         struct buffer_head *head;
 403         loff_t isize = i_size_read(inode);
 404
 405         memset(pages, 0, num_pages * sizeof(struct page *));
 406
 407         for (i = 0; i < num_pages; i++) {
 408                 pages[i] = grab_cache_page(inode->i_mapping, index + i);
 409                 if (!pages[i]) {
 410                         err = -ENOMEM;
 411                         goto failed_release;
 412                 }
 413                 cancel_dirty_page(pages[i], PAGE_CACHE_SIZE);
 414                 wait_on_page_writeback(pages[i]);
 415                 offset = pos & (PAGE_CACHE_SIZE -1);
 416                 this_write = min((size_t)PAGE_CACHE_SIZE - offset, write_bytes);
 417                 if (!page_has_buffers(pages[i])) {
 418                         create_empty_buffers(pages[i],
 419                                              root->fs_info->sb->s_blocksize,
 420                                              (1 << BH_Uptodate));
 421                 }
 422                 head = page_buffers(pages[i]);
 423                 bh = head;
 424                 do {
 425                         err = btrfs_map_bh_to_logical(root, bh,
 426                                                       alloc_extent_start);
 427                         BUG_ON(err);
 428                         if (err)
 429                                 goto failed_truncate;
 430                         bh = bh->b_this_page;
 431                         if (alloc_extent_start)
 432                                 alloc_extent_start++;
 433                 } while (bh != head);
 434                 pos += this_write;
 435                 WARN_ON(this_write > write_bytes);
 436                 write_bytes -= this_write;
 437         }
 438         return 0;
 439
 440 failed_release:
 441         btrfs_drop_pages(pages, num_pages);
 442         return err;
 443
 444 failed_truncate:
 445         btrfs_drop_pages(pages, num_pages);
 446         if (pos > isize)
 447                 vmtruncate(inode, isize);
 448         return err;
 449 }
 450
 451 static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
 452                                 size_t count, loff_t *ppos)
 453 {
 454         loff_t pos;
 455         size_t num_written = 0;
 456         int err = 0;
 457         int ret = 0;
 458         struct inode *inode = file->f_path.dentry->d_inode;
 459         struct btrfs_root *root = BTRFS_I(inode)->root;
 460         struct page *pages[8];
 461         struct page *pinned[2];
 462         unsigned long first_index;
 463         unsigned long last_index;
 464         u64 start_pos;
 465         u64 num_blocks;
 466         u64 alloc_extent_start;
 467         u64 hint_block;
 468         struct btrfs_trans_handle *trans;
 469         struct btrfs_key ins;
 470         pinned[0] = NULL;
 471         pinned[1] = NULL;
 472         if (file->f_flags & O_DIRECT)
 473                 return -EINVAL;
 474         pos = *ppos;
 475         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
 476         current->backing_dev_info = inode->i_mapping->backing_dev_info;
 477         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
 478         if (err)
 479                 goto out;
 480         if (count == 0)
 481                 goto out;
 482         err = remove_suid(file->f_path.dentry);
 483         if (err)
 484                 goto out;
 485         file_update_time(file);
 486
 487         start_pos = pos & ~((u64)PAGE_CACHE_SIZE - 1);
 488         num_blocks = (count + pos - start_pos + root->blocksize - 1) >>
 489                         inode->i_blkbits;
 490
 491         mutex_lock(&inode->i_mutex);
 492         first_index = pos >> PAGE_CACHE_SHIFT;
 493         last_index = (pos + count) >> PAGE_CACHE_SHIFT;
 494
 495         /*
 496          * there are lots of better ways to do this, but this code
 497          * makes sure the first and last page in the file range are
 498          * up to date and ready for cow
 499          */
 500         if ((pos & (PAGE_CACHE_SIZE - 1))) {
 501                 pinned[0] = grab_cache_page(inode->i_mapping, first_index);
 502                 if (!PageUptodate(pinned[0])) {
 503                         ret = mpage_readpage(pinned[0], btrfs_get_block);
 504                         BUG_ON(ret);
 505                         wait_on_page_locked(pinned[0]);
 506                 } else {
 507                         unlock_page(pinned[0]);
 508                 }
 509         }
 510         if ((pos + count) & (PAGE_CACHE_SIZE - 1)) {
 511                 pinned[1] = grab_cache_page(inode->i_mapping, last_index);
 512                 if (!PageUptodate(pinned[1])) {
 513                         ret = mpage_readpage(pinned[1], btrfs_get_block);
 514                         BUG_ON(ret);
 515                         wait_on_page_locked(pinned[1]);
 516                 } else {
 517                         unlock_page(pinned[1]);
 518                 }
 519         }
 520
 521         mutex_lock(&root->fs_info->fs_mutex);
 522         trans = btrfs_start_transaction(root, 1);
 523         if (!trans) {
 524                 err = -ENOMEM;
 525                 mutex_unlock(&root->fs_info->fs_mutex);
 526                 goto out_unlock;
 527         }
 528         btrfs_set_trans_block_group(trans, inode);
 529         /* FIXME blocksize != 4096 */
 530         inode->i_blocks += num_blocks << 3;
 531         hint_block = 0;
 532
 533         /* FIXME...EIEIO, ENOSPC and more */
 534
 535         /* step one, delete the existing extents in this range */
 536         if (start_pos < inode->i_size) {
 537                 /* FIXME blocksize != pagesize */
 538                 ret = btrfs_drop_extents(trans, root, inode,
 539                                          start_pos,
 540                                          (pos + count + root->blocksize -1) &
 541                                          ~((u64)root->blocksize - 1),
 542                                          &hint_block);
 543                 BUG_ON(ret);
 544         }
 545
 546         /* insert any holes we need to create */
 547         if (inode->i_size < start_pos) {
 548                 u64 last_pos_in_file;
 549                 u64 hole_size;
 550                 u64 mask = root->blocksize - 1;
 551                 last_pos_in_file = (inode->i_size + mask) & ~mask;
 552                 hole_size = (start_pos - last_pos_in_file + mask) & ~mask;
 553                 hole_size >>= inode->i_blkbits;
 554                 if (last_pos_in_file < start_pos) {
 555                         ret = btrfs_insert_file_extent(trans, root,
 556                                                        inode->i_ino,
 557                                                        last_pos_in_file,
 558                                                        0, 0, hole_size);
 559                 }
 560                 BUG_ON(ret);
 561         }
 562
 563         /*
 564          * either allocate an extent for the new bytes or setup the key
 565          * to show we are doing inline data in the extent
 566          */
 567         if (inode->i_size >= PAGE_CACHE_SIZE || pos + count < inode->i_size ||
 568             pos + count - start_pos > BTRFS_MAX_INLINE_DATA_SIZE(root)) {
 569                 ret = btrfs_alloc_extent(trans, root, inode->i_ino,
 570                                          num_blocks, hint_block, (u64)-1,
 571                                          &ins, 1);
 572                 BUG_ON(ret);
 573                 ret = btrfs_insert_file_extent(trans, root, inode->i_ino,
 574                                        start_pos, ins.objectid, ins.offset,
 575                                        ins.offset);
 576                 BUG_ON(ret);
 577         } else {
 578                 ins.offset = 0;
 579                 ins.objectid = 0;
 580         }
 581         BUG_ON(ret);
 582         alloc_extent_start = ins.objectid;
 583         ret = btrfs_end_transaction(trans, root);
 584         mutex_unlock(&root->fs_info->fs_mutex);
 585
 586         while(count > 0) {
 587                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
 588                 size_t write_bytes = min(count,
 589                                          (size_t)PAGE_CACHE_SIZE - offset);
 590                 size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
 591                                         PAGE_CACHE_SHIFT;
 592
 593                 memset(pages, 0, sizeof(pages));
 594                 ret = prepare_pages(root, file, pages, num_pages,
 595                                     pos, first_index, last_index,
 596                                     write_bytes, alloc_extent_start);
 597                 BUG_ON(ret);
 598
 599                 /* FIXME blocks != pagesize */
 600                 if (alloc_extent_start)
 601                         alloc_extent_start += num_pages;
 602                 ret = btrfs_copy_from_user(pos, num_pages,
 603                                            write_bytes, pages, buf);
 604                 BUG_ON(ret);
 605
 606                 ret = dirty_and_release_pages(NULL, root, file, pages,
 607                                               num_pages, pos, write_bytes);
 608                 BUG_ON(ret);
 609                 btrfs_drop_pages(pages, num_pages);
 610
 611                 buf += write_bytes;
 612                 count -= write_bytes;
 613                 pos += write_bytes;
 614                 num_written += write_bytes;
 615
 616                 balance_dirty_pages_ratelimited(inode->i_mapping);
 617                 btrfs_btree_balance_dirty(root);
 618                 cond_resched();
 619         }
 620 out_unlock:
 621         mutex_unlock(&inode->i_mutex);
 622 out:
 623         if (pinned[0])
 624                 page_cache_release(pinned[0]);
 625         if (pinned[1])
 626                 page_cache_release(pinned[1]);
 627         *ppos = pos;
 628         current->backing_dev_info = NULL;
 629         mark_inode_dirty(inode);
 630         return num_written ? num_written : err;
 631 }
 632
 633 /*
 634  * FIXME, do this by stuffing the csum we want in the info hanging off
 635  * page->private.  For now, verify file csums on read
 636  */
 637 static int btrfs_read_actor(read_descriptor_t *desc, struct page *page,
 638                         unsigned long offset, unsigned long size)
 639 {
 640         char *kaddr;
 641         unsigned long left, count = desc->count;
 642         struct inode *inode = page->mapping->host;
 643
 644         if (size > count)
 645                 size = count;
 646
 647         if (!PageChecked(page)) {
 648                 /* FIXME, do it per block */
 649                 struct btrfs_root *root = BTRFS_I(inode)->root;
 650                 int ret;
 651                 struct buffer_head *bh;
 652
 653                 if (page_has_buffers(page)) {
 654                         bh = page_buffers(page);
 655                         if (!buffer_mapped(bh)) {
 656                                 SetPageChecked(page);
 657                                 goto checked;
 658                         }
 659                 }
 660
 661                 ret = btrfs_csum_verify_file_block(root,
 662                                   page->mapping->host->i_ino,
 663                                   page->index << PAGE_CACHE_SHIFT,
 664                                   kmap(page), PAGE_CACHE_SIZE);
 665                 if (ret) {
 666                         if (ret != -ENOENT) {
 667                                 printk("failed to verify ino %lu page %lu ret %d\n",
 668                                        page->mapping->host->i_ino,
 669                                        page->index, ret);
 670                                 memset(page_address(page), 1, PAGE_CACHE_SIZE);
 671                                 flush_dcache_page(page);
 672                         }
 673                 }
 674                 SetPageChecked(page);
 675                 kunmap(page);
 676         }
 677 checked:
 678         /*
 679          * Faults on the destination of a read are common, so do it before
 680          * taking the kmap.
 681          */
 682         if (!fault_in_pages_writeable(desc->arg.buf, size)) {
 683                 kaddr = kmap_atomic(page, KM_USER0);
 684                 left = __copy_to_user_inatomic(desc->arg.buf,
 685                                                 kaddr + offset, size);
 686                 kunmap_atomic(kaddr, KM_USER0);
 687                 if (left == 0)
 688                         goto success;
 689         }
 690
 691         /* Do it the slow way */
 692         kaddr = kmap(page);
 693         left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
 694         kunmap(page);
 695
 696         if (left) {
 697                 size -= left;
 698                 desc->error = -EFAULT;
 699         }
 700 success:
 701         desc->count = count - size;
 702         desc->written += size;
 703         desc->arg.buf += size;
 704         return size;
 705 }
 706
 707 /**
 708  * btrfs_file_aio_read - filesystem read routine, with a mod to csum verify
 709  * @iocb:       kernel I/O control block
 710  * @iov:        io vector request
 711  * @nr_segs:    number of segments in the iovec
 712  * @pos:        current file position
 713  */
 714 static ssize_t btrfs_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
 715                                    unsigned long nr_segs, loff_t pos)
 716 {
 717         struct file *filp = iocb->ki_filp;
 718         ssize_t retval;
 719         unsigned long seg;
 720         size_t count;
 721         loff_t *ppos = &iocb->ki_pos;
 722
 723         count = 0;
 724         for (seg = 0; seg < nr_segs; seg++) {
 725                 const struct iovec *iv = &iov[seg];
 726
 727                 /*
 728                  * If any segment has a negative length, or the cumulative
 729                  * length ever wraps negative then return -EINVAL.
 730                  */
 731                 count += iv->iov_len;
 732                 if (unlikely((ssize_t)(count|iv->iov_len) < 0))
 733                         return -EINVAL;
 734                 if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len))
 735                         continue;
 736                 if (seg == 0)
 737                         return -EFAULT;
 738                 nr_segs = seg;
 739                 count -= iv->iov_len;   /* This segment is no good */
 740                 break;
 741         }
 742         retval = 0;
 743         if (count) {
 744                 for (seg = 0; seg < nr_segs; seg++) {
 745                         read_descriptor_t desc;
 746
 747                         desc.written = 0;
 748                         desc.arg.buf = iov[seg].iov_base;
 749                         desc.count = iov[seg].iov_len;
 750                         if (desc.count == 0)
 751                                 continue;
 752                         desc.error = 0;
 753                         do_generic_file_read(filp, ppos, &desc,
 754                                              btrfs_read_actor);
 755                         retval += desc.written;
 756                         if (desc.error) {
 757                                 retval = retval ?: desc.error;
 758                                 break;
 759                         }
 760                 }
 761         }
 762         return retval;
 763 }
 764
 765 static int btrfs_sync_file(struct file *file,
 766                            struct dentry *dentry, int datasync)
 767 {
 768         struct inode *inode = dentry->d_inode;
 769         struct btrfs_root *root = BTRFS_I(inode)->root;
 770         int ret;
 771         struct btrfs_trans_handle *trans;
 772
 773         /*
 774          * FIXME, use inode generation number to check if we can skip the
 775          * commit
 776          */
 777         mutex_lock(&root->fs_info->fs_mutex);
 778         trans = btrfs_start_transaction(root, 1);
 779         if (!trans) {
 780                 ret = -ENOMEM;
 781                 goto out;
 782         }
 783         ret = btrfs_commit_transaction(trans, root);
 784         mutex_unlock(&root->fs_info->fs_mutex);
 785 out:
 786         return ret > 0 ? EIO : ret;
 787 }
 788
 789 struct file_operations btrfs_file_operations = {
 790         .llseek         = generic_file_llseek,
 791         .read           = do_sync_read,
 792         .aio_read       = btrfs_file_aio_read,
 793         .write          = btrfs_file_write,
 794         .mmap           = generic_file_mmap,
 795         .open           = generic_file_open,
 796         .ioctl          = btrfs_ioctl,
 797         .fsync          = btrfs_sync_file,
 798 #ifdef CONFIG_COMPAT
 799         .compat_ioctl   = btrfs_compat_ioctl,
 800 #endif
 801 };
 802