ocfs2: fix locking for res->tracking and dlm->tracking_list
[linux/fpc-iii.git] / fs / ext4 / move_extent.c
blob05048fcfd602cdca1c24bbbc03de7c0174740a19
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>
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.
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.
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"
23 /**
24 * get_ext_path - Find an extent path for designated logical block number.
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)
30 * ext4_find_extent wrapper. Return 0 on success, or a negative error value
31 * on failure.
33 static inline int
34 get_ext_path(struct inode *inode, ext4_lblk_t lblock,
35 struct ext4_ext_path **ppath)
37 struct ext4_ext_path *path;
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;
48 *ppath = path;
49 return 0;
52 /**
53 * ext4_double_down_write_data_sem - Acquire two inodes' write lock
54 * of i_data_sem
56 * Acquire write lock of i_data_sem of the two inodes
58 void
59 ext4_double_down_write_data_sem(struct inode *first, struct inode *second)
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);
71 /**
72 * ext4_double_up_write_data_sem - Release two inodes' write lock of i_data_sem
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).
78 void
79 ext4_double_up_write_data_sem(struct inode *orig_inode,
80 struct inode *donor_inode)
82 up_write(&EXT4_I(orig_inode)->i_data_sem);
83 up_write(&EXT4_I(donor_inode)->i_data_sem);
86 /**
87 * mext_check_coverage - Check that all extents in range has the same type
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
95 * Return 1 if all extents in range has expected type, and zero otherwise.
97 static int
98 mext_check_coverage(struct inode *inode, ext4_lblk_t from, ext4_lblk_t count,
99 int unwritten, int *err)
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);
115 ret = 1;
116 out:
117 ext4_ext_drop_refs(path);
118 kfree(path);
119 return ret;
123 * mext_page_double_lock - Grab and lock pages on both @inode1 and @inode2
125 * @inode1: the inode structure
126 * @inode2: the inode structure
127 * @index1: page index
128 * @index2: page index
129 * @page: result page vector
131 * Grab two locked pages for inode's by inode order
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])
137 struct address_space *mapping[2];
138 unsigned fl = AOP_FLAG_NOFS;
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;
152 page[0] = grab_cache_page_write_begin(mapping[0], index1, fl);
153 if (!page[0])
154 return -ENOMEM;
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;
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
167 wait_on_page_writeback(page[0]);
168 wait_on_page_writeback(page[1]);
169 if (inode1 > inode2)
170 swap(page[0], page[1]);
172 return 0;
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)
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));
187 if (PageUptodate(page))
188 return 0;
190 blocksize = i_blocksize(inode);
191 if (!page_has_buffers(page))
192 create_empty_buffers(page, blocksize, 0);
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;
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;
212 if (!buffer_mapped(bh)) {
213 zero_user(page, block_start, blocksize);
214 set_buffer_uptodate(bh);
215 continue;
218 BUG_ON(nr >= MAX_BUF_PER_PAGE);
219 arr[nr++] = bh;
221 /* No io required */
222 if (!nr)
223 goto out;
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;
233 out:
234 if (!partial)
235 SetPageUptodate(page);
236 return 0;
240 * move_extent_per_page - Move extent data per page
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
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.
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)
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_CACHE_SIZE >> orig_inode->i_blkbits;
272 struct super_block *sb = orig_inode->i_sb;
273 struct buffer_head *bh = NULL;
276 * It needs twice the amount of ordinary journal buffers because
277 * inode and donor_inode may change each different metadata blocks.
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;
288 orig_blk_offset = orig_page_offset * blocks_per_page +
289 data_offset_in_page;
291 donor_blk_offset = donor_page_offset * blocks_per_page +
292 data_offset_in_page;
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);
300 * If data_size equal zero, it shows data_size is multiples of
301 * blocksize. So we set appropriate value.
303 if (tmp_data_size == 0)
304 tmp_data_size = blocksize;
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;
311 replaced_size = data_size;
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;
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.
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;
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;
338 if (!unwritten) {
339 ext4_double_up_write_data_sem(orig_inode, donor_inode);
340 goto data_copy;
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;
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;
357 data_copy:
358 *err = mext_page_mkuptodate(pagep[0], from, from + replaced_size);
359 if (*err)
360 goto unlock_pages;
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;
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;
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;
395 if (!*err)
396 *err = block_commit_write(pagep[0], from, from + replaced_size);
398 if (unlikely(*err < 0))
399 goto repair_branches;
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_file_inode(handle, orig_inode);
405 unlock_pages:
406 unlock_page(pagep[0]);
407 page_cache_release(pagep[0]);
408 unlock_page(pagep[1]);
409 page_cache_release(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;
422 repair_branches:
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
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;
439 replaced_count = 0;
440 goto unlock_pages;
444 * mext_check_arguments - Check whether move extent can be done
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
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.
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)
461 __u64 orig_eof, donor_eof;
462 unsigned int blkbits = orig_inode->i_blkbits;
463 unsigned int blocksize = 1 << blkbits;
465 orig_eof = (i_size_read(orig_inode) + blocksize - 1) >> blkbits;
466 donor_eof = (i_size_read(donor_inode) + blocksize - 1) >> blkbits;
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;
476 if (IS_IMMUTABLE(donor_inode) || IS_APPEND(donor_inode))
477 return -EPERM;
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;
487 if (IS_NOQUOTA(orig_inode) || IS_NOQUOTA(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;
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;
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;
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 "offset are not alligned [ino:orig %lu, donor %lu]\n",
515 orig_inode->i_ino, donor_inode->i_ino);
516 return -EINVAL;
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;
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;
540 return 0;
544 * ext4_move_extents - Exchange the specified range of a file
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
553 * This function returns 0 and moved block length is set in moved_len
554 * if succeed, otherwise returns error value.
558 ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 orig_blk,
559 __u64 donor_blk, __u64 len, __u64 *moved_len)
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_CACHE_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;
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;
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;
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;
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;
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;
608 /* Protect orig and donor inodes against a truncate */
609 lock_two_nondirectories(orig_inode, donor_inode);
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);
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;
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;
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;
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;
661 unwritten = ext4_ext_is_unwritten(ex);
662 if (o_end - o_start < cur_len)
663 cur_len = o_end - o_start;
665 orig_page_index = o_start >> (PAGE_CACHE_SHIFT -
666 orig_inode->i_blkbits);
667 donor_page_index = d_start >> (PAGE_CACHE_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;
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
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;
691 *moved_len = o_start - orig_blk;
692 if (*moved_len > len)
693 *moved_len = len;
695 out:
696 if (*moved_len) {
697 ext4_discard_preallocations(orig_inode);
698 ext4_discard_preallocations(donor_inode);
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);
708 return ret;