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, I_DATA_SEM_OTHER); 64 } else { 65 down_write(&EXT4_I(second)->i_data_sem); 66 down_write_nested(&EXT4_I(first)->i_data_sem, I_DATA_SEM_OTHER); 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 put_page(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 = i_blocksize(inode); 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_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 i, 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_SIZE >> orig_inode->i_blkbits; 272 struct super_block *sb = orig_inode->i_sb; 273 struct buffer_head *bh = NULL; 274 275 /* 276 * It needs twice the amount of ordinary journal buffers because 277 * inode and donor_inode may change each different metadata blocks. 278 */ 279 again: 280 *err = 0; 281 jblocks = ext4_writepage_trans_blocks(orig_inode) * 2; 282 handle = ext4_journal_start(orig_inode, EXT4_HT_MOVE_EXTENTS, jblocks); 283 if (IS_ERR(handle)) { 284 *err = PTR_ERR(handle); 285 return 0; 286 } 287 288 orig_blk_offset = orig_page_offset * blocks_per_page + 289 data_offset_in_page; 290 291 donor_blk_offset = donor_page_offset * blocks_per_page + 292 data_offset_in_page; 293 294 /* Calculate data_size */ 295 if ((orig_blk_offset + block_len_in_page - 1) == 296 ((orig_inode->i_size - 1) >> orig_inode->i_blkbits)) { 297 /* Replace the last block */ 298 tmp_data_size = orig_inode->i_size & (blocksize - 1); 299 /* 300 * If data_size equal zero, it shows data_size is multiples of 301 * blocksize. So we set appropriate value. 302 */ 303 if (tmp_data_size == 0) 304 tmp_data_size = blocksize; 305 306 data_size = tmp_data_size + 307 ((block_len_in_page - 1) << orig_inode->i_blkbits); 308 } else 309 data_size = block_len_in_page << orig_inode->i_blkbits; 310 311 replaced_size = data_size; 312 313 *err = mext_page_double_lock(orig_inode, donor_inode, orig_page_offset, 314 donor_page_offset, pagep); 315 if (unlikely(*err < 0)) 316 goto stop_journal; 317 /* 318 * If orig extent was unwritten it can become initialized 319 * at any time after i_data_sem was dropped, in order to 320 * serialize with delalloc we have recheck extent while we 321 * hold page's lock, if it is still the case data copy is not 322 * necessary, just swap data blocks between orig and donor. 323 */ 324 if (unwritten) { 325 ext4_double_down_write_data_sem(orig_inode, donor_inode); 326 /* If any of extents in range became initialized we have to 327 * fallback to data copying */ 328 unwritten = mext_check_coverage(orig_inode, orig_blk_offset, 329 block_len_in_page, 1, err); 330 if (*err) 331 goto drop_data_sem; 332 333 unwritten &= mext_check_coverage(donor_inode, donor_blk_offset, 334 block_len_in_page, 1, err); 335 if (*err) 336 goto drop_data_sem; 337 338 if (!unwritten) { 339 ext4_double_up_write_data_sem(orig_inode, donor_inode); 340 goto data_copy; 341 } 342 if ((page_has_private(pagep[0]) && 343 !try_to_release_page(pagep[0], 0)) || 344 (page_has_private(pagep[1]) && 345 !try_to_release_page(pagep[1], 0))) { 346 *err = -EBUSY; 347 goto drop_data_sem; 348 } 349 replaced_count = ext4_swap_extents(handle, orig_inode, 350 donor_inode, orig_blk_offset, 351 donor_blk_offset, 352 block_len_in_page, 1, err); 353 drop_data_sem: 354 ext4_double_up_write_data_sem(orig_inode, donor_inode); 355 goto unlock_pages; 356 } 357 data_copy: 358 *err = mext_page_mkuptodate(pagep[0], from, from + replaced_size); 359 if (*err) 360 goto unlock_pages; 361 362 /* At this point all buffers in range are uptodate, old mapping layout 363 * is no longer required, try to drop it now. */ 364 if ((page_has_private(pagep[0]) && !try_to_release_page(pagep[0], 0)) || 365 (page_has_private(pagep[1]) && !try_to_release_page(pagep[1], 0))) { 366 *err = -EBUSY; 367 goto unlock_pages; 368 } 369 ext4_double_down_write_data_sem(orig_inode, donor_inode); 370 replaced_count = ext4_swap_extents(handle, orig_inode, donor_inode, 371 orig_blk_offset, donor_blk_offset, 372 block_len_in_page, 1, err); 373 ext4_double_up_write_data_sem(orig_inode, donor_inode); 374 if (*err) { 375 if (replaced_count) { 376 block_len_in_page = replaced_count; 377 replaced_size = 378 block_len_in_page << orig_inode->i_blkbits; 379 } else 380 goto unlock_pages; 381 } 382 /* Perform all necessary steps similar write_begin()/write_end() 383 * but keeping in mind that i_size will not change */ 384 if (!page_has_buffers(pagep[0])) 385 create_empty_buffers(pagep[0], 1 << orig_inode->i_blkbits, 0); 386 bh = page_buffers(pagep[0]); 387 for (i = 0; i < data_offset_in_page; i++) 388 bh = bh->b_this_page; 389 for (i = 0; i < block_len_in_page; i++) { 390 *err = ext4_get_block(orig_inode, orig_blk_offset + i, bh, 0); 391 if (*err < 0) 392 break; 393 bh = bh->b_this_page; 394 } 395 if (!*err) 396 *err = block_commit_write(pagep[0], from, from + replaced_size); 397 398 if (unlikely(*err < 0)) 399 goto repair_branches; 400 401 /* Even in case of data=writeback it is reasonable to pin 402 * inode to transaction, to prevent unexpected data loss */ 403 *err = ext4_jbd2_inode_add_write(handle, orig_inode); 404 405 unlock_pages: 406 unlock_page(pagep[0]); 407 put_page(pagep[0]); 408 unlock_page(pagep[1]); 409 put_page(pagep[1]); 410 stop_journal: 411 ext4_journal_stop(handle); 412 if (*err == -ENOSPC && 413 ext4_should_retry_alloc(sb, &retries)) 414 goto again; 415 /* Buffer was busy because probably is pinned to journal transaction, 416 * force transaction commit may help to free it. */ 417 if (*err == -EBUSY && retries++ < 4 && EXT4_SB(sb)->s_journal && 418 jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal)) 419 goto again; 420 return replaced_count; 421 422 repair_branches: 423 /* 424 * This should never ever happen! 425 * Extents are swapped already, but we are not able to copy data. 426 * Try to swap extents to it's original places 427 */ 428 ext4_double_down_write_data_sem(orig_inode, donor_inode); 429 replaced_count = ext4_swap_extents(handle, donor_inode, orig_inode, 430 orig_blk_offset, donor_blk_offset, 431 block_len_in_page, 0, &err2); 432 ext4_double_up_write_data_sem(orig_inode, donor_inode); 433 if (replaced_count != block_len_in_page) { 434 EXT4_ERROR_INODE_BLOCK(orig_inode, (sector_t)(orig_blk_offset), 435 "Unable to copy data block," 436 " data will be lost."); 437 *err = -EIO; 438 } 439 replaced_count = 0; 440 goto unlock_pages; 441 } 442 443 /** 444 * mext_check_arguments - Check whether move extent can be done 445 * 446 * @orig_inode: original inode 447 * @donor_inode: donor inode 448 * @orig_start: logical start offset in block for orig 449 * @donor_start: logical start offset in block for donor 450 * @len: the number of blocks to be moved 451 * 452 * Check the arguments of ext4_move_extents() whether the files can be 453 * exchanged with each other. 454 * Return 0 on success, or a negative error value on failure. 455 */ 456 static int 457 mext_check_arguments(struct inode *orig_inode, 458 struct inode *donor_inode, __u64 orig_start, 459 __u64 donor_start, __u64 *len) 460 { 461 __u64 orig_eof, donor_eof; 462 unsigned int blkbits = orig_inode->i_blkbits; 463 unsigned int blocksize = 1 << blkbits; 464 465 orig_eof = (i_size_read(orig_inode) + blocksize - 1) >> blkbits; 466 donor_eof = (i_size_read(donor_inode) + blocksize - 1) >> blkbits; 467 468 469 if (donor_inode->i_mode & (S_ISUID|S_ISGID)) { 470 ext4_debug("ext4 move extent: suid or sgid is set" 471 " to donor file [ino:orig %lu, donor %lu]\n", 472 orig_inode->i_ino, donor_inode->i_ino); 473 return -EINVAL; 474 } 475 476 if (IS_IMMUTABLE(donor_inode) || IS_APPEND(donor_inode)) 477 return -EPERM; 478 479 /* Ext4 move extent does not support swapfile */ 480 if (IS_SWAPFILE(orig_inode) || IS_SWAPFILE(donor_inode)) { 481 ext4_debug("ext4 move extent: The argument files should " 482 "not be swapfile [ino:orig %lu, donor %lu]\n", 483 orig_inode->i_ino, donor_inode->i_ino); 484 return -EBUSY; 485 } 486 487 if (ext4_is_quota_file(orig_inode) && ext4_is_quota_file(donor_inode)) { 488 ext4_debug("ext4 move extent: The argument files should " 489 "not be quota files [ino:orig %lu, donor %lu]\n", 490 orig_inode->i_ino, donor_inode->i_ino); 491 return -EBUSY; 492 } 493 494 /* Ext4 move extent supports only extent based file */ 495 if (!(ext4_test_inode_flag(orig_inode, EXT4_INODE_EXTENTS))) { 496 ext4_debug("ext4 move extent: orig file is not extents " 497 "based file [ino:orig %lu]\n", orig_inode->i_ino); 498 return -EOPNOTSUPP; 499 } else if (!(ext4_test_inode_flag(donor_inode, EXT4_INODE_EXTENTS))) { 500 ext4_debug("ext4 move extent: donor file is not extents " 501 "based file [ino:donor %lu]\n", donor_inode->i_ino); 502 return -EOPNOTSUPP; 503 } 504 505 if ((!orig_inode->i_size) || (!donor_inode->i_size)) { 506 ext4_debug("ext4 move extent: File size is 0 byte\n"); 507 return -EINVAL; 508 } 509 510 /* Start offset should be same */ 511 if ((orig_start & ~(PAGE_MASK >> orig_inode->i_blkbits)) != 512 (donor_start & ~(PAGE_MASK >> orig_inode->i_blkbits))) { 513 ext4_debug("ext4 move extent: orig and donor's start " 514 "offsets are not aligned [ino:orig %lu, donor %lu]\n", 515 orig_inode->i_ino, donor_inode->i_ino); 516 return -EINVAL; 517 } 518 519 if ((orig_start >= EXT_MAX_BLOCKS) || 520 (donor_start >= EXT_MAX_BLOCKS) || 521 (*len > EXT_MAX_BLOCKS) || 522 (donor_start + *len >= EXT_MAX_BLOCKS) || 523 (orig_start + *len >= EXT_MAX_BLOCKS)) { 524 ext4_debug("ext4 move extent: Can't handle over [%u] blocks " 525 "[ino:orig %lu, donor %lu]\n", EXT_MAX_BLOCKS, 526 orig_inode->i_ino, donor_inode->i_ino); 527 return -EINVAL; 528 } 529 if (orig_eof < orig_start + *len - 1) 530 *len = orig_eof - orig_start; 531 if (donor_eof < donor_start + *len - 1) 532 *len = donor_eof - donor_start; 533 if (!*len) { 534 ext4_debug("ext4 move extent: len should not be 0 " 535 "[ino:orig %lu, donor %lu]\n", orig_inode->i_ino, 536 donor_inode->i_ino); 537 return -EINVAL; 538 } 539 540 return 0; 541 } 542 543 /** 544 * ext4_move_extents - Exchange the specified range of a file 545 * 546 * @o_filp: file structure of the original file 547 * @d_filp: file structure of the donor file 548 * @orig_blk: start offset in block for orig 549 * @donor_blk: start offset in block for donor 550 * @len: the number of blocks to be moved 551 * @moved_len: moved block length 552 * 553 * This function returns 0 and moved block length is set in moved_len 554 * if succeed, otherwise returns error value. 555 * 556 */ 557 int 558 ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 orig_blk, 559 __u64 donor_blk, __u64 len, __u64 *moved_len) 560 { 561 struct inode *orig_inode = file_inode(o_filp); 562 struct inode *donor_inode = file_inode(d_filp); 563 struct ext4_ext_path *path = NULL; 564 int blocks_per_page = PAGE_SIZE >> orig_inode->i_blkbits; 565 ext4_lblk_t o_end, o_start = orig_blk; 566 ext4_lblk_t d_start = donor_blk; 567 int ret; 568 569 if (orig_inode->i_sb != donor_inode->i_sb) { 570 ext4_debug("ext4 move extent: The argument files " 571 "should be in same FS [ino:orig %lu, donor %lu]\n", 572 orig_inode->i_ino, donor_inode->i_ino); 573 return -EINVAL; 574 } 575 576 /* orig and donor should be different inodes */ 577 if (orig_inode == donor_inode) { 578 ext4_debug("ext4 move extent: The argument files should not " 579 "be same inode [ino:orig %lu, donor %lu]\n", 580 orig_inode->i_ino, donor_inode->i_ino); 581 return -EINVAL; 582 } 583 584 /* Regular file check */ 585 if (!S_ISREG(orig_inode->i_mode) || !S_ISREG(donor_inode->i_mode)) { 586 ext4_debug("ext4 move extent: The argument files should be " 587 "regular file [ino:orig %lu, donor %lu]\n", 588 orig_inode->i_ino, donor_inode->i_ino); 589 return -EINVAL; 590 } 591 592 /* TODO: it's not obvious how to swap blocks for inodes with full 593 journaling enabled */ 594 if (ext4_should_journal_data(orig_inode) || 595 ext4_should_journal_data(donor_inode)) { 596 ext4_msg(orig_inode->i_sb, KERN_ERR, 597 "Online defrag not supported with data journaling"); 598 return -EOPNOTSUPP; 599 } 600 601 if (ext4_encrypted_inode(orig_inode) || 602 ext4_encrypted_inode(donor_inode)) { 603 ext4_msg(orig_inode->i_sb, KERN_ERR, 604 "Online defrag not supported for encrypted files"); 605 return -EOPNOTSUPP; 606 } 607 608 /* Protect orig and donor inodes against a truncate */ 609 lock_two_nondirectories(orig_inode, donor_inode); 610 611 /* Wait for all existing dio workers */ 612 ext4_inode_block_unlocked_dio(orig_inode); 613 ext4_inode_block_unlocked_dio(donor_inode); 614 inode_dio_wait(orig_inode); 615 inode_dio_wait(donor_inode); 616 617 /* Protect extent tree against block allocations via delalloc */ 618 ext4_double_down_write_data_sem(orig_inode, donor_inode); 619 /* Check the filesystem environment whether move_extent can be done */ 620 ret = mext_check_arguments(orig_inode, donor_inode, orig_blk, 621 donor_blk, &len); 622 if (ret) 623 goto out; 624 o_end = o_start + len; 625 626 while (o_start < o_end) { 627 struct ext4_extent *ex; 628 ext4_lblk_t cur_blk, next_blk; 629 pgoff_t orig_page_index, donor_page_index; 630 int offset_in_page; 631 int unwritten, cur_len; 632 633 ret = get_ext_path(orig_inode, o_start, &path); 634 if (ret) 635 goto out; 636 ex = path[path->p_depth].p_ext; 637 next_blk = ext4_ext_next_allocated_block(path); 638 cur_blk = le32_to_cpu(ex->ee_block); 639 cur_len = ext4_ext_get_actual_len(ex); 640 /* Check hole before the start pos */ 641 if (cur_blk + cur_len - 1 < o_start) { 642 if (next_blk == EXT_MAX_BLOCKS) { 643 o_start = o_end; 644 ret = -ENODATA; 645 goto out; 646 } 647 d_start += next_blk - o_start; 648 o_start = next_blk; 649 continue; 650 /* Check hole after the start pos */ 651 } else if (cur_blk > o_start) { 652 /* Skip hole */ 653 d_start += cur_blk - o_start; 654 o_start = cur_blk; 655 /* Extent inside requested range ?*/ 656 if (cur_blk >= o_end) 657 goto out; 658 } else { /* in_range(o_start, o_blk, o_len) */ 659 cur_len += cur_blk - o_start; 660 } 661 unwritten = ext4_ext_is_unwritten(ex); 662 if (o_end - o_start < cur_len) 663 cur_len = o_end - o_start; 664 665 orig_page_index = o_start >> (PAGE_SHIFT - 666 orig_inode->i_blkbits); 667 donor_page_index = d_start >> (PAGE_SHIFT - 668 donor_inode->i_blkbits); 669 offset_in_page = o_start % blocks_per_page; 670 if (cur_len > blocks_per_page- offset_in_page) 671 cur_len = blocks_per_page - offset_in_page; 672 /* 673 * Up semaphore to avoid following problems: 674 * a. transaction deadlock among ext4_journal_start, 675 * ->write_begin via pagefault, and jbd2_journal_commit 676 * b. racing with ->readpage, ->write_begin, and ext4_get_block 677 * in move_extent_per_page 678 */ 679 ext4_double_up_write_data_sem(orig_inode, donor_inode); 680 /* Swap original branches with new branches */ 681 move_extent_per_page(o_filp, donor_inode, 682 orig_page_index, donor_page_index, 683 offset_in_page, cur_len, 684 unwritten, &ret); 685 ext4_double_down_write_data_sem(orig_inode, donor_inode); 686 if (ret < 0) 687 break; 688 o_start += cur_len; 689 d_start += cur_len; 690 } 691 *moved_len = o_start - orig_blk; 692 if (*moved_len > len) 693 *moved_len = len; 694 695 out: 696 if (*moved_len) { 697 ext4_discard_preallocations(orig_inode); 698 ext4_discard_preallocations(donor_inode); 699 } 700 701 ext4_ext_drop_refs(path); 702 kfree(path); 703 ext4_double_up_write_data_sem(orig_inode, donor_inode); 704 ext4_inode_resume_unlocked_dio(orig_inode); 705 ext4_inode_resume_unlocked_dio(donor_inode); 706 unlock_two_nondirectories(orig_inode, donor_inode); 707 708 return ret; 709 } 710