1 /* 2 * Copyright (c) 2008,2009 NEC Software Tohoku, Ltd. 3 * Written by Takashi Sato <t-sato@yk.jp.nec.com> 4 * Akira Fujita <a-fujita@rs.jp.nec.com> 5 * 6 * This program is free software; you can redistribute it and/or modify it 7 * under the terms of version 2.1 of the GNU Lesser General Public License 8 * as published by the Free Software Foundation. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 */ 15 16 #include <linux/fs.h> 17 #include <linux/quotaops.h> 18 #include <linux/slab.h> 19 #include "ext4_jbd2.h" 20 #include "ext4.h" 21 #include "ext4_extents.h" 22 23 /** 24 * get_ext_path - Find an extent path for designated logical block number. 25 * 26 * @inode: an inode which is searched 27 * @lblock: logical block number to find an extent path 28 * @path: pointer to an extent path pointer (for output) 29 * 30 * ext4_find_extent wrapper. Return 0 on success, or a negative error value 31 * on failure. 32 */ 33 static inline int 34 get_ext_path(struct inode *inode, ext4_lblk_t lblock, 35 struct ext4_ext_path **ppath) 36 { 37 struct ext4_ext_path *path; 38 39 path = ext4_find_extent(inode, lblock, ppath, EXT4_EX_NOCACHE); 40 if (IS_ERR(path)) 41 return PTR_ERR(path); 42 if (path[ext_depth(inode)].p_ext == NULL) { 43 ext4_ext_drop_refs(path); 44 kfree(path); 45 *ppath = NULL; 46 return -ENODATA; 47 } 48 *ppath = path; 49 return 0; 50 } 51 52 /** 53 * ext4_double_down_write_data_sem - Acquire two inodes' write lock 54 * of i_data_sem 55 * 56 * Acquire write lock of i_data_sem of the two inodes 57 */ 58 void 59 ext4_double_down_write_data_sem(struct inode *first, struct inode *second) 60 { 61 if (first < second) { 62 down_write(&EXT4_I(first)->i_data_sem); 63 down_write_nested(&EXT4_I(second)->i_data_sem, SINGLE_DEPTH_NESTING); 64 } else { 65 down_write(&EXT4_I(second)->i_data_sem); 66 down_write_nested(&EXT4_I(first)->i_data_sem, SINGLE_DEPTH_NESTING); 67 68 } 69 } 70 71 /** 72 * ext4_double_up_write_data_sem - Release two inodes' write lock of i_data_sem 73 * 74 * @orig_inode: original inode structure to be released its lock first 75 * @donor_inode: donor inode structure to be released its lock second 76 * Release write lock of i_data_sem of two inodes (orig and donor). 77 */ 78 void 79 ext4_double_up_write_data_sem(struct inode *orig_inode, 80 struct inode *donor_inode) 81 { 82 up_write(&EXT4_I(orig_inode)->i_data_sem); 83 up_write(&EXT4_I(donor_inode)->i_data_sem); 84 } 85 86 /** 87 * mext_check_coverage - Check that all extents in range has the same type 88 * 89 * @inode: inode in question 90 * @from: block offset of inode 91 * @count: block count to be checked 92 * @unwritten: extents expected to be unwritten 93 * @err: pointer to save error value 94 * 95 * Return 1 if all extents in range has expected type, and zero otherwise. 96 */ 97 static int 98 mext_check_coverage(struct inode *inode, ext4_lblk_t from, ext4_lblk_t count, 99 int unwritten, int *err) 100 { 101 struct ext4_ext_path *path = NULL; 102 struct ext4_extent *ext; 103 int ret = 0; 104 ext4_lblk_t last = from + count; 105 while (from < last) { 106 *err = get_ext_path(inode, from, &path); 107 if (*err) 108 goto out; 109 ext = path[ext_depth(inode)].p_ext; 110 if (unwritten != ext4_ext_is_unwritten(ext)) 111 goto out; 112 from += ext4_ext_get_actual_len(ext); 113 ext4_ext_drop_refs(path); 114 } 115 ret = 1; 116 out: 117 ext4_ext_drop_refs(path); 118 kfree(path); 119 return ret; 120 } 121 122 /** 123 * mext_page_double_lock - Grab and lock pages on both @inode1 and @inode2 124 * 125 * @inode1: the inode structure 126 * @inode2: the inode structure 127 * @index1: page index 128 * @index2: page index 129 * @page: result page vector 130 * 131 * Grab two locked pages for inode's by inode order 132 */ 133 static int 134 mext_page_double_lock(struct inode *inode1, struct inode *inode2, 135 pgoff_t index1, pgoff_t index2, struct page *page[2]) 136 { 137 struct address_space *mapping[2]; 138 unsigned fl = AOP_FLAG_NOFS; 139 140 BUG_ON(!inode1 || !inode2); 141 if (inode1 < inode2) { 142 mapping[0] = inode1->i_mapping; 143 mapping[1] = inode2->i_mapping; 144 } else { 145 pgoff_t tmp = index1; 146 index1 = index2; 147 index2 = tmp; 148 mapping[0] = inode2->i_mapping; 149 mapping[1] = inode1->i_mapping; 150 } 151 152 page[0] = grab_cache_page_write_begin(mapping[0], index1, fl); 153 if (!page[0]) 154 return -ENOMEM; 155 156 page[1] = grab_cache_page_write_begin(mapping[1], index2, fl); 157 if (!page[1]) { 158 unlock_page(page[0]); 159 page_cache_release(page[0]); 160 return -ENOMEM; 161 } 162 /* 163 * grab_cache_page_write_begin() may not wait on page's writeback if 164 * BDI not demand that. But it is reasonable to be very conservative 165 * here and explicitly wait on page's writeback 166 */ 167 wait_on_page_writeback(page[0]); 168 wait_on_page_writeback(page[1]); 169 if (inode1 > inode2) { 170 struct page *tmp; 171 tmp = page[0]; 172 page[0] = page[1]; 173 page[1] = tmp; 174 } 175 return 0; 176 } 177 178 /* Force page buffers uptodate w/o dropping page's lock */ 179 static int 180 mext_page_mkuptodate(struct page *page, unsigned from, unsigned to) 181 { 182 struct inode *inode = page->mapping->host; 183 sector_t block; 184 struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; 185 unsigned int blocksize, block_start, block_end; 186 int i, err, nr = 0, partial = 0; 187 BUG_ON(!PageLocked(page)); 188 BUG_ON(PageWriteback(page)); 189 190 if (PageUptodate(page)) 191 return 0; 192 193 blocksize = 1 << inode->i_blkbits; 194 if (!page_has_buffers(page)) 195 create_empty_buffers(page, blocksize, 0); 196 197 head = page_buffers(page); 198 block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); 199 for (bh = head, block_start = 0; bh != head || !block_start; 200 block++, block_start = block_end, bh = bh->b_this_page) { 201 block_end = block_start + blocksize; 202 if (block_end <= from || block_start >= to) { 203 if (!buffer_uptodate(bh)) 204 partial = 1; 205 continue; 206 } 207 if (buffer_uptodate(bh)) 208 continue; 209 if (!buffer_mapped(bh)) { 210 err = ext4_get_block(inode, block, bh, 0); 211 if (err) { 212 SetPageError(page); 213 return err; 214 } 215 if (!buffer_mapped(bh)) { 216 zero_user(page, block_start, blocksize); 217 set_buffer_uptodate(bh); 218 continue; 219 } 220 } 221 BUG_ON(nr >= MAX_BUF_PER_PAGE); 222 arr[nr++] = bh; 223 } 224 /* No io required */ 225 if (!nr) 226 goto out; 227 228 for (i = 0; i < nr; i++) { 229 bh = arr[i]; 230 if (!bh_uptodate_or_lock(bh)) { 231 err = bh_submit_read(bh); 232 if (err) 233 return err; 234 } 235 } 236 out: 237 if (!partial) 238 SetPageUptodate(page); 239 return 0; 240 } 241 242 /** 243 * move_extent_per_page - Move extent data per page 244 * 245 * @o_filp: file structure of original file 246 * @donor_inode: donor inode 247 * @orig_page_offset: page index on original file 248 * @donor_page_offset: page index on donor file 249 * @data_offset_in_page: block index where data swapping starts 250 * @block_len_in_page: the number of blocks to be swapped 251 * @unwritten: orig extent is unwritten or not 252 * @err: pointer to save return value 253 * 254 * Save the data in original inode blocks and replace original inode extents 255 * with donor inode extents by calling ext4_swap_extents(). 256 * Finally, write out the saved data in new original inode blocks. Return 257 * replaced block count. 258 */ 259 static int 260 move_extent_per_page(struct file *o_filp, struct inode *donor_inode, 261 pgoff_t orig_page_offset, pgoff_t donor_page_offset, 262 int data_offset_in_page, 263 int block_len_in_page, int unwritten, int *err) 264 { 265 struct inode *orig_inode = file_inode(o_filp); 266 struct page *pagep[2] = {NULL, NULL}; 267 handle_t *handle; 268 ext4_lblk_t orig_blk_offset, donor_blk_offset; 269 unsigned long blocksize = orig_inode->i_sb->s_blocksize; 270 unsigned int w_flags = 0; 271 unsigned int tmp_data_size, data_size, replaced_size; 272 int err2, jblocks, retries = 0; 273 int replaced_count = 0; 274 int from = data_offset_in_page << orig_inode->i_blkbits; 275 int blocks_per_page = PAGE_CACHE_SIZE >> orig_inode->i_blkbits; 276 277 /* 278 * It needs twice the amount of ordinary journal buffers because 279 * inode and donor_inode may change each different metadata blocks. 280 */ 281 again: 282 *err = 0; 283 jblocks = ext4_writepage_trans_blocks(orig_inode) * 2; 284 handle = ext4_journal_start(orig_inode, EXT4_HT_MOVE_EXTENTS, jblocks); 285 if (IS_ERR(handle)) { 286 *err = PTR_ERR(handle); 287 return 0; 288 } 289 290 if (segment_eq(get_fs(), KERNEL_DS)) 291 w_flags |= AOP_FLAG_UNINTERRUPTIBLE; 292 293 orig_blk_offset = orig_page_offset * blocks_per_page + 294 data_offset_in_page; 295 296 donor_blk_offset = donor_page_offset * blocks_per_page + 297 data_offset_in_page; 298 299 /* Calculate data_size */ 300 if ((orig_blk_offset + block_len_in_page - 1) == 301 ((orig_inode->i_size - 1) >> orig_inode->i_blkbits)) { 302 /* Replace the last block */ 303 tmp_data_size = orig_inode->i_size & (blocksize - 1); 304 /* 305 * If data_size equal zero, it shows data_size is multiples of 306 * blocksize. So we set appropriate value. 307 */ 308 if (tmp_data_size == 0) 309 tmp_data_size = blocksize; 310 311 data_size = tmp_data_size + 312 ((block_len_in_page - 1) << orig_inode->i_blkbits); 313 } else 314 data_size = block_len_in_page << orig_inode->i_blkbits; 315 316 replaced_size = data_size; 317 318 *err = mext_page_double_lock(orig_inode, donor_inode, orig_page_offset, 319 donor_page_offset, pagep); 320 if (unlikely(*err < 0)) 321 goto stop_journal; 322 /* 323 * If orig extent was unwritten it can become initialized 324 * at any time after i_data_sem was dropped, in order to 325 * serialize with delalloc we have recheck extent while we 326 * hold page's lock, if it is still the case data copy is not 327 * necessary, just swap data blocks between orig and donor. 328 */ 329 if (unwritten) { 330 ext4_double_down_write_data_sem(orig_inode, donor_inode); 331 /* If any of extents in range became initialized we have to 332 * fallback to data copying */ 333 unwritten = mext_check_coverage(orig_inode, orig_blk_offset, 334 block_len_in_page, 1, err); 335 if (*err) 336 goto drop_data_sem; 337 338 unwritten &= mext_check_coverage(donor_inode, donor_blk_offset, 339 block_len_in_page, 1, err); 340 if (*err) 341 goto drop_data_sem; 342 343 if (!unwritten) { 344 ext4_double_up_write_data_sem(orig_inode, donor_inode); 345 goto data_copy; 346 } 347 if ((page_has_private(pagep[0]) && 348 !try_to_release_page(pagep[0], 0)) || 349 (page_has_private(pagep[1]) && 350 !try_to_release_page(pagep[1], 0))) { 351 *err = -EBUSY; 352 goto drop_data_sem; 353 } 354 replaced_count = ext4_swap_extents(handle, orig_inode, 355 donor_inode, orig_blk_offset, 356 donor_blk_offset, 357 block_len_in_page, 1, err); 358 drop_data_sem: 359 ext4_double_up_write_data_sem(orig_inode, donor_inode); 360 goto unlock_pages; 361 } 362 data_copy: 363 *err = mext_page_mkuptodate(pagep[0], from, from + replaced_size); 364 if (*err) 365 goto unlock_pages; 366 367 /* At this point all buffers in range are uptodate, old mapping layout 368 * is no longer required, try to drop it now. */ 369 if ((page_has_private(pagep[0]) && !try_to_release_page(pagep[0], 0)) || 370 (page_has_private(pagep[1]) && !try_to_release_page(pagep[1], 0))) { 371 *err = -EBUSY; 372 goto unlock_pages; 373 } 374 ext4_double_down_write_data_sem(orig_inode, donor_inode); 375 replaced_count = ext4_swap_extents(handle, orig_inode, donor_inode, 376 orig_blk_offset, donor_blk_offset, 377 block_len_in_page, 1, err); 378 ext4_double_up_write_data_sem(orig_inode, donor_inode); 379 if (*err) { 380 if (replaced_count) { 381 block_len_in_page = replaced_count; 382 replaced_size = 383 block_len_in_page << orig_inode->i_blkbits; 384 } else 385 goto unlock_pages; 386 } 387 /* Perform all necessary steps similar write_begin()/write_end() 388 * but keeping in mind that i_size will not change */ 389 *err = __block_write_begin(pagep[0], from, replaced_size, 390 ext4_get_block); 391 if (!*err) 392 *err = block_commit_write(pagep[0], from, from + replaced_size); 393 394 if (unlikely(*err < 0)) 395 goto repair_branches; 396 397 /* Even in case of data=writeback it is reasonable to pin 398 * inode to transaction, to prevent unexpected data loss */ 399 *err = ext4_jbd2_file_inode(handle, orig_inode); 400 401 unlock_pages: 402 unlock_page(pagep[0]); 403 page_cache_release(pagep[0]); 404 unlock_page(pagep[1]); 405 page_cache_release(pagep[1]); 406 stop_journal: 407 ext4_journal_stop(handle); 408 /* Buffer was busy because probably is pinned to journal transaction, 409 * force transaction commit may help to free it. */ 410 if (*err == -EBUSY && ext4_should_retry_alloc(orig_inode->i_sb, 411 &retries)) 412 goto again; 413 return replaced_count; 414 415 repair_branches: 416 /* 417 * This should never ever happen! 418 * Extents are swapped already, but we are not able to copy data. 419 * Try to swap extents to it's original places 420 */ 421 ext4_double_down_write_data_sem(orig_inode, donor_inode); 422 replaced_count = ext4_swap_extents(handle, donor_inode, orig_inode, 423 orig_blk_offset, donor_blk_offset, 424 block_len_in_page, 0, &err2); 425 ext4_double_up_write_data_sem(orig_inode, donor_inode); 426 if (replaced_count != block_len_in_page) { 427 EXT4_ERROR_INODE_BLOCK(orig_inode, (sector_t)(orig_blk_offset), 428 "Unable to copy data block," 429 " data will be lost."); 430 *err = -EIO; 431 } 432 replaced_count = 0; 433 goto unlock_pages; 434 } 435 436 /** 437 * mext_check_arguments - Check whether move extent can be done 438 * 439 * @orig_inode: original inode 440 * @donor_inode: donor inode 441 * @orig_start: logical start offset in block for orig 442 * @donor_start: logical start offset in block for donor 443 * @len: the number of blocks to be moved 444 * 445 * Check the arguments of ext4_move_extents() whether the files can be 446 * exchanged with each other. 447 * Return 0 on success, or a negative error value on failure. 448 */ 449 static int 450 mext_check_arguments(struct inode *orig_inode, 451 struct inode *donor_inode, __u64 orig_start, 452 __u64 donor_start, __u64 *len) 453 { 454 __u64 orig_eof, donor_eof; 455 unsigned int blkbits = orig_inode->i_blkbits; 456 unsigned int blocksize = 1 << blkbits; 457 458 orig_eof = (i_size_read(orig_inode) + blocksize - 1) >> blkbits; 459 donor_eof = (i_size_read(donor_inode) + blocksize - 1) >> blkbits; 460 461 462 if (donor_inode->i_mode & (S_ISUID|S_ISGID)) { 463 ext4_debug("ext4 move extent: suid or sgid is set" 464 " to donor file [ino:orig %lu, donor %lu]\n", 465 orig_inode->i_ino, donor_inode->i_ino); 466 return -EINVAL; 467 } 468 469 if (IS_IMMUTABLE(donor_inode) || IS_APPEND(donor_inode)) 470 return -EPERM; 471 472 /* Ext4 move extent does not support swapfile */ 473 if (IS_SWAPFILE(orig_inode) || IS_SWAPFILE(donor_inode)) { 474 ext4_debug("ext4 move extent: The argument files should " 475 "not be swapfile [ino:orig %lu, donor %lu]\n", 476 orig_inode->i_ino, donor_inode->i_ino); 477 return -EBUSY; 478 } 479 480 /* Ext4 move extent supports only extent based file */ 481 if (!(ext4_test_inode_flag(orig_inode, EXT4_INODE_EXTENTS))) { 482 ext4_debug("ext4 move extent: orig file is not extents " 483 "based file [ino:orig %lu]\n", orig_inode->i_ino); 484 return -EOPNOTSUPP; 485 } else if (!(ext4_test_inode_flag(donor_inode, EXT4_INODE_EXTENTS))) { 486 ext4_debug("ext4 move extent: donor file is not extents " 487 "based file [ino:donor %lu]\n", donor_inode->i_ino); 488 return -EOPNOTSUPP; 489 } 490 491 if ((!orig_inode->i_size) || (!donor_inode->i_size)) { 492 ext4_debug("ext4 move extent: File size is 0 byte\n"); 493 return -EINVAL; 494 } 495 496 /* Start offset should be same */ 497 if ((orig_start & ~(PAGE_MASK >> orig_inode->i_blkbits)) != 498 (donor_start & ~(PAGE_MASK >> orig_inode->i_blkbits))) { 499 ext4_debug("ext4 move extent: orig and donor's start " 500 "offset are not alligned [ino:orig %lu, donor %lu]\n", 501 orig_inode->i_ino, donor_inode->i_ino); 502 return -EINVAL; 503 } 504 505 if ((orig_start >= EXT_MAX_BLOCKS) || 506 (donor_start >= EXT_MAX_BLOCKS) || 507 (*len > EXT_MAX_BLOCKS) || 508 (donor_start + *len >= EXT_MAX_BLOCKS) || 509 (orig_start + *len >= EXT_MAX_BLOCKS)) { 510 ext4_debug("ext4 move extent: Can't handle over [%u] blocks " 511 "[ino:orig %lu, donor %lu]\n", EXT_MAX_BLOCKS, 512 orig_inode->i_ino, donor_inode->i_ino); 513 return -EINVAL; 514 } 515 if (orig_eof < orig_start + *len - 1) 516 *len = orig_eof - orig_start; 517 if (donor_eof < donor_start + *len - 1) 518 *len = donor_eof - donor_start; 519 if (!*len) { 520 ext4_debug("ext4 move extent: len should not be 0 " 521 "[ino:orig %lu, donor %lu]\n", orig_inode->i_ino, 522 donor_inode->i_ino); 523 return -EINVAL; 524 } 525 526 return 0; 527 } 528 529 /** 530 * ext4_move_extents - Exchange the specified range of a file 531 * 532 * @o_filp: file structure of the original file 533 * @d_filp: file structure of the donor file 534 * @orig_blk: start offset in block for orig 535 * @donor_blk: start offset in block for donor 536 * @len: the number of blocks to be moved 537 * @moved_len: moved block length 538 * 539 * This function returns 0 and moved block length is set in moved_len 540 * if succeed, otherwise returns error value. 541 * 542 */ 543 int 544 ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 orig_blk, 545 __u64 donor_blk, __u64 len, __u64 *moved_len) 546 { 547 struct inode *orig_inode = file_inode(o_filp); 548 struct inode *donor_inode = file_inode(d_filp); 549 struct ext4_ext_path *path = NULL; 550 int blocks_per_page = PAGE_CACHE_SIZE >> orig_inode->i_blkbits; 551 ext4_lblk_t o_end, o_start = orig_blk; 552 ext4_lblk_t d_start = donor_blk; 553 int ret; 554 555 if (orig_inode->i_sb != donor_inode->i_sb) { 556 ext4_debug("ext4 move extent: The argument files " 557 "should be in same FS [ino:orig %lu, donor %lu]\n", 558 orig_inode->i_ino, donor_inode->i_ino); 559 return -EINVAL; 560 } 561 562 /* orig and donor should be different inodes */ 563 if (orig_inode == donor_inode) { 564 ext4_debug("ext4 move extent: The argument files should not " 565 "be same inode [ino:orig %lu, donor %lu]\n", 566 orig_inode->i_ino, donor_inode->i_ino); 567 return -EINVAL; 568 } 569 570 /* Regular file check */ 571 if (!S_ISREG(orig_inode->i_mode) || !S_ISREG(donor_inode->i_mode)) { 572 ext4_debug("ext4 move extent: The argument files should be " 573 "regular file [ino:orig %lu, donor %lu]\n", 574 orig_inode->i_ino, donor_inode->i_ino); 575 return -EINVAL; 576 } 577 /* TODO: This is non obvious task to swap blocks for inodes with full 578 jornaling enabled */ 579 if (ext4_should_journal_data(orig_inode) || 580 ext4_should_journal_data(donor_inode)) { 581 return -EINVAL; 582 } 583 /* Protect orig and donor inodes against a truncate */ 584 lock_two_nondirectories(orig_inode, donor_inode); 585 586 /* Wait for all existing dio workers */ 587 ext4_inode_block_unlocked_dio(orig_inode); 588 ext4_inode_block_unlocked_dio(donor_inode); 589 inode_dio_wait(orig_inode); 590 inode_dio_wait(donor_inode); 591 592 /* Protect extent tree against block allocations via delalloc */ 593 ext4_double_down_write_data_sem(orig_inode, donor_inode); 594 /* Check the filesystem environment whether move_extent can be done */ 595 ret = mext_check_arguments(orig_inode, donor_inode, orig_blk, 596 donor_blk, &len); 597 if (ret) 598 goto out; 599 o_end = o_start + len; 600 601 while (o_start < o_end) { 602 struct ext4_extent *ex; 603 ext4_lblk_t cur_blk, next_blk; 604 pgoff_t orig_page_index, donor_page_index; 605 int offset_in_page; 606 int unwritten, cur_len; 607 608 ret = get_ext_path(orig_inode, o_start, &path); 609 if (ret) 610 goto out; 611 ex = path[path->p_depth].p_ext; 612 next_blk = ext4_ext_next_allocated_block(path); 613 cur_blk = le32_to_cpu(ex->ee_block); 614 cur_len = ext4_ext_get_actual_len(ex); 615 /* Check hole before the start pos */ 616 if (cur_blk + cur_len - 1 < o_start) { 617 if (next_blk == EXT_MAX_BLOCKS) { 618 o_start = o_end; 619 ret = -ENODATA; 620 goto out; 621 } 622 d_start += next_blk - o_start; 623 o_start = next_blk; 624 continue; 625 /* Check hole after the start pos */ 626 } else if (cur_blk > o_start) { 627 /* Skip hole */ 628 d_start += cur_blk - o_start; 629 o_start = cur_blk; 630 /* Extent inside requested range ?*/ 631 if (cur_blk >= o_end) 632 goto out; 633 } else { /* in_range(o_start, o_blk, o_len) */ 634 cur_len += cur_blk - o_start; 635 } 636 unwritten = ext4_ext_is_unwritten(ex); 637 if (o_end - o_start < cur_len) 638 cur_len = o_end - o_start; 639 640 orig_page_index = o_start >> (PAGE_CACHE_SHIFT - 641 orig_inode->i_blkbits); 642 donor_page_index = d_start >> (PAGE_CACHE_SHIFT - 643 donor_inode->i_blkbits); 644 offset_in_page = o_start % blocks_per_page; 645 if (cur_len > blocks_per_page- offset_in_page) 646 cur_len = blocks_per_page - offset_in_page; 647 /* 648 * Up semaphore to avoid following problems: 649 * a. transaction deadlock among ext4_journal_start, 650 * ->write_begin via pagefault, and jbd2_journal_commit 651 * b. racing with ->readpage, ->write_begin, and ext4_get_block 652 * in move_extent_per_page 653 */ 654 ext4_double_up_write_data_sem(orig_inode, donor_inode); 655 /* Swap original branches with new branches */ 656 move_extent_per_page(o_filp, donor_inode, 657 orig_page_index, donor_page_index, 658 offset_in_page, cur_len, 659 unwritten, &ret); 660 ext4_double_down_write_data_sem(orig_inode, donor_inode); 661 if (ret < 0) 662 break; 663 o_start += cur_len; 664 d_start += cur_len; 665 } 666 *moved_len = o_start - orig_blk; 667 if (*moved_len > len) 668 *moved_len = len; 669 670 out: 671 if (*moved_len) { 672 ext4_discard_preallocations(orig_inode); 673 ext4_discard_preallocations(donor_inode); 674 } 675 676 ext4_ext_drop_refs(path); 677 kfree(path); 678 ext4_double_up_write_data_sem(orig_inode, donor_inode); 679 ext4_inode_resume_unlocked_dio(orig_inode); 680 ext4_inode_resume_unlocked_dio(donor_inode); 681 unlock_two_nondirectories(orig_inode, donor_inode); 682 683 return ret; 684 } 685