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 swap(page[0], page[1]); 171 172 return 0; 173 } 174 175 /* Force page buffers uptodate w/o dropping page's lock */ 176 static int 177 mext_page_mkuptodate(struct page *page, unsigned from, unsigned to) 178 { 179 struct inode *inode = page->mapping->host; 180 sector_t block; 181 struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; 182 unsigned int blocksize, block_start, block_end; 183 int i, err, nr = 0, partial = 0; 184 BUG_ON(!PageLocked(page)); 185 BUG_ON(PageWriteback(page)); 186 187 if (PageUptodate(page)) 188 return 0; 189 190 blocksize = 1 << inode->i_blkbits; 191 if (!page_has_buffers(page)) 192 create_empty_buffers(page, blocksize, 0); 193 194 head = page_buffers(page); 195 block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); 196 for (bh = head, block_start = 0; bh != head || !block_start; 197 block++, block_start = block_end, bh = bh->b_this_page) { 198 block_end = block_start + blocksize; 199 if (block_end <= from || block_start >= to) { 200 if (!buffer_uptodate(bh)) 201 partial = 1; 202 continue; 203 } 204 if (buffer_uptodate(bh)) 205 continue; 206 if (!buffer_mapped(bh)) { 207 err = ext4_get_block(inode, block, bh, 0); 208 if (err) { 209 SetPageError(page); 210 return err; 211 } 212 if (!buffer_mapped(bh)) { 213 zero_user(page, block_start, blocksize); 214 set_buffer_uptodate(bh); 215 continue; 216 } 217 } 218 BUG_ON(nr >= MAX_BUF_PER_PAGE); 219 arr[nr++] = bh; 220 } 221 /* No io required */ 222 if (!nr) 223 goto out; 224 225 for (i = 0; i < nr; i++) { 226 bh = arr[i]; 227 if (!bh_uptodate_or_lock(bh)) { 228 err = bh_submit_read(bh); 229 if (err) 230 return err; 231 } 232 } 233 out: 234 if (!partial) 235 SetPageUptodate(page); 236 return 0; 237 } 238 239 /** 240 * move_extent_per_page - Move extent data per page 241 * 242 * @o_filp: file structure of original file 243 * @donor_inode: donor inode 244 * @orig_page_offset: page index on original file 245 * @donor_page_offset: page index on donor file 246 * @data_offset_in_page: block index where data swapping starts 247 * @block_len_in_page: the number of blocks to be swapped 248 * @unwritten: orig extent is unwritten or not 249 * @err: pointer to save return value 250 * 251 * Save the data in original inode blocks and replace original inode extents 252 * with donor inode extents by calling ext4_swap_extents(). 253 * Finally, write out the saved data in new original inode blocks. Return 254 * replaced block count. 255 */ 256 static int 257 move_extent_per_page(struct file *o_filp, struct inode *donor_inode, 258 pgoff_t orig_page_offset, pgoff_t donor_page_offset, 259 int data_offset_in_page, 260 int block_len_in_page, int unwritten, int *err) 261 { 262 struct inode *orig_inode = file_inode(o_filp); 263 struct page *pagep[2] = {NULL, NULL}; 264 handle_t *handle; 265 ext4_lblk_t orig_blk_offset, donor_blk_offset; 266 unsigned long blocksize = orig_inode->i_sb->s_blocksize; 267 unsigned int tmp_data_size, data_size, replaced_size; 268 int err2, jblocks, retries = 0; 269 int replaced_count = 0; 270 int from = data_offset_in_page << orig_inode->i_blkbits; 271 int blocks_per_page = PAGE_CACHE_SIZE >> orig_inode->i_blkbits; 272 struct super_block *sb = orig_inode->i_sb; 273 274 /* 275 * It needs twice the amount of ordinary journal buffers because 276 * inode and donor_inode may change each different metadata blocks. 277 */ 278 again: 279 *err = 0; 280 jblocks = ext4_writepage_trans_blocks(orig_inode) * 2; 281 handle = ext4_journal_start(orig_inode, EXT4_HT_MOVE_EXTENTS, jblocks); 282 if (IS_ERR(handle)) { 283 *err = PTR_ERR(handle); 284 return 0; 285 } 286 287 orig_blk_offset = orig_page_offset * blocks_per_page + 288 data_offset_in_page; 289 290 donor_blk_offset = donor_page_offset * blocks_per_page + 291 data_offset_in_page; 292 293 /* Calculate data_size */ 294 if ((orig_blk_offset + block_len_in_page - 1) == 295 ((orig_inode->i_size - 1) >> orig_inode->i_blkbits)) { 296 /* Replace the last block */ 297 tmp_data_size = orig_inode->i_size & (blocksize - 1); 298 /* 299 * If data_size equal zero, it shows data_size is multiples of 300 * blocksize. So we set appropriate value. 301 */ 302 if (tmp_data_size == 0) 303 tmp_data_size = blocksize; 304 305 data_size = tmp_data_size + 306 ((block_len_in_page - 1) << orig_inode->i_blkbits); 307 } else 308 data_size = block_len_in_page << orig_inode->i_blkbits; 309 310 replaced_size = data_size; 311 312 *err = mext_page_double_lock(orig_inode, donor_inode, orig_page_offset, 313 donor_page_offset, pagep); 314 if (unlikely(*err < 0)) 315 goto stop_journal; 316 /* 317 * If orig extent was unwritten it can become initialized 318 * at any time after i_data_sem was dropped, in order to 319 * serialize with delalloc we have recheck extent while we 320 * hold page's lock, if it is still the case data copy is not 321 * necessary, just swap data blocks between orig and donor. 322 */ 323 if (unwritten) { 324 ext4_double_down_write_data_sem(orig_inode, donor_inode); 325 /* If any of extents in range became initialized we have to 326 * fallback to data copying */ 327 unwritten = mext_check_coverage(orig_inode, orig_blk_offset, 328 block_len_in_page, 1, err); 329 if (*err) 330 goto drop_data_sem; 331 332 unwritten &= mext_check_coverage(donor_inode, donor_blk_offset, 333 block_len_in_page, 1, err); 334 if (*err) 335 goto drop_data_sem; 336 337 if (!unwritten) { 338 ext4_double_up_write_data_sem(orig_inode, donor_inode); 339 goto data_copy; 340 } 341 if ((page_has_private(pagep[0]) && 342 !try_to_release_page(pagep[0], 0)) || 343 (page_has_private(pagep[1]) && 344 !try_to_release_page(pagep[1], 0))) { 345 *err = -EBUSY; 346 goto drop_data_sem; 347 } 348 replaced_count = ext4_swap_extents(handle, orig_inode, 349 donor_inode, orig_blk_offset, 350 donor_blk_offset, 351 block_len_in_page, 1, err); 352 drop_data_sem: 353 ext4_double_up_write_data_sem(orig_inode, donor_inode); 354 goto unlock_pages; 355 } 356 data_copy: 357 *err = mext_page_mkuptodate(pagep[0], from, from + replaced_size); 358 if (*err) 359 goto unlock_pages; 360 361 /* At this point all buffers in range are uptodate, old mapping layout 362 * is no longer required, try to drop it now. */ 363 if ((page_has_private(pagep[0]) && !try_to_release_page(pagep[0], 0)) || 364 (page_has_private(pagep[1]) && !try_to_release_page(pagep[1], 0))) { 365 *err = -EBUSY; 366 goto unlock_pages; 367 } 368 ext4_double_down_write_data_sem(orig_inode, donor_inode); 369 replaced_count = ext4_swap_extents(handle, orig_inode, donor_inode, 370 orig_blk_offset, donor_blk_offset, 371 block_len_in_page, 1, err); 372 ext4_double_up_write_data_sem(orig_inode, donor_inode); 373 if (*err) { 374 if (replaced_count) { 375 block_len_in_page = replaced_count; 376 replaced_size = 377 block_len_in_page << orig_inode->i_blkbits; 378 } else 379 goto unlock_pages; 380 } 381 /* Perform all necessary steps similar write_begin()/write_end() 382 * but keeping in mind that i_size will not change */ 383 *err = __block_write_begin(pagep[0], from, replaced_size, 384 ext4_get_block); 385 if (!*err) 386 *err = block_commit_write(pagep[0], from, from + replaced_size); 387 388 if (unlikely(*err < 0)) 389 goto repair_branches; 390 391 /* Even in case of data=writeback it is reasonable to pin 392 * inode to transaction, to prevent unexpected data loss */ 393 *err = ext4_jbd2_file_inode(handle, orig_inode); 394 395 unlock_pages: 396 unlock_page(pagep[0]); 397 page_cache_release(pagep[0]); 398 unlock_page(pagep[1]); 399 page_cache_release(pagep[1]); 400 stop_journal: 401 ext4_journal_stop(handle); 402 if (*err == -ENOSPC && 403 ext4_should_retry_alloc(sb, &retries)) 404 goto again; 405 /* Buffer was busy because probably is pinned to journal transaction, 406 * force transaction commit may help to free it. */ 407 if (*err == -EBUSY && retries++ < 4 && EXT4_SB(sb)->s_journal && 408 jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal)) 409 goto again; 410 return replaced_count; 411 412 repair_branches: 413 /* 414 * This should never ever happen! 415 * Extents are swapped already, but we are not able to copy data. 416 * Try to swap extents to it's original places 417 */ 418 ext4_double_down_write_data_sem(orig_inode, donor_inode); 419 replaced_count = ext4_swap_extents(handle, donor_inode, orig_inode, 420 orig_blk_offset, donor_blk_offset, 421 block_len_in_page, 0, &err2); 422 ext4_double_up_write_data_sem(orig_inode, donor_inode); 423 if (replaced_count != block_len_in_page) { 424 EXT4_ERROR_INODE_BLOCK(orig_inode, (sector_t)(orig_blk_offset), 425 "Unable to copy data block," 426 " data will be lost."); 427 *err = -EIO; 428 } 429 replaced_count = 0; 430 goto unlock_pages; 431 } 432 433 /** 434 * mext_check_arguments - Check whether move extent can be done 435 * 436 * @orig_inode: original inode 437 * @donor_inode: donor inode 438 * @orig_start: logical start offset in block for orig 439 * @donor_start: logical start offset in block for donor 440 * @len: the number of blocks to be moved 441 * 442 * Check the arguments of ext4_move_extents() whether the files can be 443 * exchanged with each other. 444 * Return 0 on success, or a negative error value on failure. 445 */ 446 static int 447 mext_check_arguments(struct inode *orig_inode, 448 struct inode *donor_inode, __u64 orig_start, 449 __u64 donor_start, __u64 *len) 450 { 451 __u64 orig_eof, donor_eof; 452 unsigned int blkbits = orig_inode->i_blkbits; 453 unsigned int blocksize = 1 << blkbits; 454 455 orig_eof = (i_size_read(orig_inode) + blocksize - 1) >> blkbits; 456 donor_eof = (i_size_read(donor_inode) + blocksize - 1) >> blkbits; 457 458 459 if (donor_inode->i_mode & (S_ISUID|S_ISGID)) { 460 ext4_debug("ext4 move extent: suid or sgid is set" 461 " to donor file [ino:orig %lu, donor %lu]\n", 462 orig_inode->i_ino, donor_inode->i_ino); 463 return -EINVAL; 464 } 465 466 if (IS_IMMUTABLE(donor_inode) || IS_APPEND(donor_inode)) 467 return -EPERM; 468 469 /* Ext4 move extent does not support swapfile */ 470 if (IS_SWAPFILE(orig_inode) || IS_SWAPFILE(donor_inode)) { 471 ext4_debug("ext4 move extent: The argument files should " 472 "not be swapfile [ino:orig %lu, donor %lu]\n", 473 orig_inode->i_ino, donor_inode->i_ino); 474 return -EBUSY; 475 } 476 477 /* Ext4 move extent supports only extent based file */ 478 if (!(ext4_test_inode_flag(orig_inode, EXT4_INODE_EXTENTS))) { 479 ext4_debug("ext4 move extent: orig file is not extents " 480 "based file [ino:orig %lu]\n", orig_inode->i_ino); 481 return -EOPNOTSUPP; 482 } else if (!(ext4_test_inode_flag(donor_inode, EXT4_INODE_EXTENTS))) { 483 ext4_debug("ext4 move extent: donor file is not extents " 484 "based file [ino:donor %lu]\n", donor_inode->i_ino); 485 return -EOPNOTSUPP; 486 } 487 488 if ((!orig_inode->i_size) || (!donor_inode->i_size)) { 489 ext4_debug("ext4 move extent: File size is 0 byte\n"); 490 return -EINVAL; 491 } 492 493 /* Start offset should be same */ 494 if ((orig_start & ~(PAGE_MASK >> orig_inode->i_blkbits)) != 495 (donor_start & ~(PAGE_MASK >> orig_inode->i_blkbits))) { 496 ext4_debug("ext4 move extent: orig and donor's start " 497 "offset are not alligned [ino:orig %lu, donor %lu]\n", 498 orig_inode->i_ino, donor_inode->i_ino); 499 return -EINVAL; 500 } 501 502 if ((orig_start >= EXT_MAX_BLOCKS) || 503 (donor_start >= EXT_MAX_BLOCKS) || 504 (*len > EXT_MAX_BLOCKS) || 505 (donor_start + *len >= EXT_MAX_BLOCKS) || 506 (orig_start + *len >= EXT_MAX_BLOCKS)) { 507 ext4_debug("ext4 move extent: Can't handle over [%u] blocks " 508 "[ino:orig %lu, donor %lu]\n", EXT_MAX_BLOCKS, 509 orig_inode->i_ino, donor_inode->i_ino); 510 return -EINVAL; 511 } 512 if (orig_eof < orig_start + *len - 1) 513 *len = orig_eof - orig_start; 514 if (donor_eof < donor_start + *len - 1) 515 *len = donor_eof - donor_start; 516 if (!*len) { 517 ext4_debug("ext4 move extent: len should not be 0 " 518 "[ino:orig %lu, donor %lu]\n", orig_inode->i_ino, 519 donor_inode->i_ino); 520 return -EINVAL; 521 } 522 523 return 0; 524 } 525 526 /** 527 * ext4_move_extents - Exchange the specified range of a file 528 * 529 * @o_filp: file structure of the original file 530 * @d_filp: file structure of the donor file 531 * @orig_blk: start offset in block for orig 532 * @donor_blk: start offset in block for donor 533 * @len: the number of blocks to be moved 534 * @moved_len: moved block length 535 * 536 * This function returns 0 and moved block length is set in moved_len 537 * if succeed, otherwise returns error value. 538 * 539 */ 540 int 541 ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 orig_blk, 542 __u64 donor_blk, __u64 len, __u64 *moved_len) 543 { 544 struct inode *orig_inode = file_inode(o_filp); 545 struct inode *donor_inode = file_inode(d_filp); 546 struct ext4_ext_path *path = NULL; 547 int blocks_per_page = PAGE_CACHE_SIZE >> orig_inode->i_blkbits; 548 ext4_lblk_t o_end, o_start = orig_blk; 549 ext4_lblk_t d_start = donor_blk; 550 int ret; 551 552 if (orig_inode->i_sb != donor_inode->i_sb) { 553 ext4_debug("ext4 move extent: The argument files " 554 "should be in same FS [ino:orig %lu, donor %lu]\n", 555 orig_inode->i_ino, donor_inode->i_ino); 556 return -EINVAL; 557 } 558 559 /* orig and donor should be different inodes */ 560 if (orig_inode == donor_inode) { 561 ext4_debug("ext4 move extent: The argument files should not " 562 "be same inode [ino:orig %lu, donor %lu]\n", 563 orig_inode->i_ino, donor_inode->i_ino); 564 return -EINVAL; 565 } 566 567 /* Regular file check */ 568 if (!S_ISREG(orig_inode->i_mode) || !S_ISREG(donor_inode->i_mode)) { 569 ext4_debug("ext4 move extent: The argument files should be " 570 "regular file [ino:orig %lu, donor %lu]\n", 571 orig_inode->i_ino, donor_inode->i_ino); 572 return -EINVAL; 573 } 574 575 /* TODO: it's not obvious how to swap blocks for inodes with full 576 journaling enabled */ 577 if (ext4_should_journal_data(orig_inode) || 578 ext4_should_journal_data(donor_inode)) { 579 ext4_msg(orig_inode->i_sb, KERN_ERR, 580 "Online defrag not supported with data journaling"); 581 return -EOPNOTSUPP; 582 } 583 584 /* Protect orig and donor inodes against a truncate */ 585 lock_two_nondirectories(orig_inode, donor_inode); 586 587 /* Wait for all existing dio workers */ 588 ext4_inode_block_unlocked_dio(orig_inode); 589 ext4_inode_block_unlocked_dio(donor_inode); 590 inode_dio_wait(orig_inode); 591 inode_dio_wait(donor_inode); 592 593 /* Protect extent tree against block allocations via delalloc */ 594 ext4_double_down_write_data_sem(orig_inode, donor_inode); 595 /* Check the filesystem environment whether move_extent can be done */ 596 ret = mext_check_arguments(orig_inode, donor_inode, orig_blk, 597 donor_blk, &len); 598 if (ret) 599 goto out; 600 o_end = o_start + len; 601 602 while (o_start < o_end) { 603 struct ext4_extent *ex; 604 ext4_lblk_t cur_blk, next_blk; 605 pgoff_t orig_page_index, donor_page_index; 606 int offset_in_page; 607 int unwritten, cur_len; 608 609 ret = get_ext_path(orig_inode, o_start, &path); 610 if (ret) 611 goto out; 612 ex = path[path->p_depth].p_ext; 613 next_blk = ext4_ext_next_allocated_block(path); 614 cur_blk = le32_to_cpu(ex->ee_block); 615 cur_len = ext4_ext_get_actual_len(ex); 616 /* Check hole before the start pos */ 617 if (cur_blk + cur_len - 1 < o_start) { 618 if (next_blk == EXT_MAX_BLOCKS) { 619 o_start = o_end; 620 ret = -ENODATA; 621 goto out; 622 } 623 d_start += next_blk - o_start; 624 o_start = next_blk; 625 continue; 626 /* Check hole after the start pos */ 627 } else if (cur_blk > o_start) { 628 /* Skip hole */ 629 d_start += cur_blk - o_start; 630 o_start = cur_blk; 631 /* Extent inside requested range ?*/ 632 if (cur_blk >= o_end) 633 goto out; 634 } else { /* in_range(o_start, o_blk, o_len) */ 635 cur_len += cur_blk - o_start; 636 } 637 unwritten = ext4_ext_is_unwritten(ex); 638 if (o_end - o_start < cur_len) 639 cur_len = o_end - o_start; 640 641 orig_page_index = o_start >> (PAGE_CACHE_SHIFT - 642 orig_inode->i_blkbits); 643 donor_page_index = d_start >> (PAGE_CACHE_SHIFT - 644 donor_inode->i_blkbits); 645 offset_in_page = o_start % blocks_per_page; 646 if (cur_len > blocks_per_page- offset_in_page) 647 cur_len = blocks_per_page - offset_in_page; 648 /* 649 * Up semaphore to avoid following problems: 650 * a. transaction deadlock among ext4_journal_start, 651 * ->write_begin via pagefault, and jbd2_journal_commit 652 * b. racing with ->readpage, ->write_begin, and ext4_get_block 653 * in move_extent_per_page 654 */ 655 ext4_double_up_write_data_sem(orig_inode, donor_inode); 656 /* Swap original branches with new branches */ 657 move_extent_per_page(o_filp, donor_inode, 658 orig_page_index, donor_page_index, 659 offset_in_page, cur_len, 660 unwritten, &ret); 661 ext4_double_down_write_data_sem(orig_inode, donor_inode); 662 if (ret < 0) 663 break; 664 o_start += cur_len; 665 d_start += cur_len; 666 } 667 *moved_len = o_start - orig_blk; 668 if (*moved_len > len) 669 *moved_len = len; 670 671 out: 672 if (*moved_len) { 673 ext4_discard_preallocations(orig_inode); 674 ext4_discard_preallocations(donor_inode); 675 } 676 677 ext4_ext_drop_refs(path); 678 kfree(path); 679 ext4_double_up_write_data_sem(orig_inode, donor_inode); 680 ext4_inode_resume_unlocked_dio(orig_inode); 681 ext4_inode_resume_unlocked_dio(donor_inode); 682 unlock_two_nondirectories(orig_inode, donor_inode); 683 684 return ret; 685 } 686