1 // SPDX-License-Identifier: GPL-2.0
3 #include <linux/blkdev.h>
4 #include <linux/iversion.h>
5 #include "compression.h"
7 #include "delalloc-space.h"
9 #include "transaction.h"
12 #define BTRFS_MAX_DEDUPE_LEN SZ_16M
14 static int clone_finish_inode_update(struct btrfs_trans_handle *trans,
21 struct btrfs_root *root = BTRFS_I(inode)->root;
24 inode_inc_iversion(inode);
26 inode->i_mtime = inode->i_ctime = current_time(inode);
28 * We round up to the block size at eof when determining which
29 * extents to clone above, but shouldn't round up the file size.
31 if (endoff > destoff + olen)
32 endoff = destoff + olen;
33 if (endoff > inode->i_size) {
34 i_size_write(inode, endoff);
35 btrfs_inode_safe_disk_i_size_write(BTRFS_I(inode), 0);
38 ret = btrfs_update_inode(trans, root, BTRFS_I(inode));
40 btrfs_abort_transaction(trans, ret);
41 btrfs_end_transaction(trans);
44 ret = btrfs_end_transaction(trans);
49 static int copy_inline_to_page(struct btrfs_inode *inode,
50 const u64 file_offset,
56 struct btrfs_fs_info *fs_info = inode->root->fs_info;
57 const u32 block_size = fs_info->sectorsize;
58 const u64 range_end = file_offset + block_size - 1;
59 const size_t inline_size = size - btrfs_file_extent_calc_inline_size(0);
60 char *data_start = inline_data + btrfs_file_extent_calc_inline_size(0);
61 struct extent_changeset *data_reserved = NULL;
62 struct page *page = NULL;
63 struct address_space *mapping = inode->vfs_inode.i_mapping;
66 ASSERT(IS_ALIGNED(file_offset, block_size));
69 * We have flushed and locked the ranges of the source and destination
70 * inodes, we also have locked the inodes, so we are safe to do a
71 * reservation here. Also we must not do the reservation while holding
72 * a transaction open, otherwise we would deadlock.
74 ret = btrfs_delalloc_reserve_space(inode, &data_reserved, file_offset,
79 page = find_or_create_page(mapping, file_offset >> PAGE_SHIFT,
80 btrfs_alloc_write_mask(mapping));
86 ret = set_page_extent_mapped(page);
90 clear_extent_bit(&inode->io_tree, file_offset, range_end,
91 EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG,
93 ret = btrfs_set_extent_delalloc(inode, file_offset, range_end, 0, NULL);
98 * After dirtying the page our caller will need to start a transaction,
99 * and if we are low on metadata free space, that can cause flushing of
100 * delalloc for all inodes in order to get metadata space released.
101 * However we are holding the range locked for the whole duration of
102 * the clone/dedupe operation, so we may deadlock if that happens and no
103 * other task releases enough space. So mark this inode as not being
104 * possible to flush to avoid such deadlock. We will clear that flag
105 * when we finish cloning all extents, since a transaction is started
106 * after finding each extent to clone.
108 set_bit(BTRFS_INODE_NO_DELALLOC_FLUSH, &inode->runtime_flags);
110 if (comp_type == BTRFS_COMPRESS_NONE) {
111 memcpy_to_page(page, offset_in_page(file_offset), data_start,
114 ret = btrfs_decompress(comp_type, data_start, page,
115 offset_in_page(file_offset),
119 flush_dcache_page(page);
123 * If our inline data is smaller then the block/page size, then the
124 * remaining of the block/page is equivalent to zeroes. We had something
125 * like the following done:
127 * $ xfs_io -f -c "pwrite -S 0xab 0 500" file
128 * $ sync # (or fsync)
129 * $ xfs_io -c "falloc 0 4K" file
130 * $ xfs_io -c "pwrite -S 0xcd 4K 4K"
132 * So what's in the range [500, 4095] corresponds to zeroes.
134 if (datal < block_size)
135 memzero_page(page, datal, block_size - datal);
137 btrfs_page_set_uptodate(fs_info, page, file_offset, block_size);
138 btrfs_page_clear_checked(fs_info, page, file_offset, block_size);
139 btrfs_page_set_dirty(fs_info, page, file_offset, block_size);
146 btrfs_delalloc_release_space(inode, data_reserved, file_offset,
148 btrfs_delalloc_release_extents(inode, block_size);
150 extent_changeset_free(data_reserved);
156 * Deal with cloning of inline extents. We try to copy the inline extent from
157 * the source inode to destination inode when possible. When not possible we
158 * copy the inline extent's data into the respective page of the inode.
160 static int clone_copy_inline_extent(struct inode *dst,
161 struct btrfs_path *path,
162 struct btrfs_key *new_key,
163 const u64 drop_start,
168 struct btrfs_trans_handle **trans_out)
170 struct btrfs_fs_info *fs_info = btrfs_sb(dst->i_sb);
171 struct btrfs_root *root = BTRFS_I(dst)->root;
172 const u64 aligned_end = ALIGN(new_key->offset + datal,
173 fs_info->sectorsize);
174 struct btrfs_trans_handle *trans = NULL;
175 struct btrfs_drop_extents_args drop_args = { 0 };
177 struct btrfs_key key;
179 if (new_key->offset > 0) {
180 ret = copy_inline_to_page(BTRFS_I(dst), new_key->offset,
181 inline_data, size, datal, comp_type);
185 key.objectid = btrfs_ino(BTRFS_I(dst));
186 key.type = BTRFS_EXTENT_DATA_KEY;
188 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
191 } else if (ret > 0) {
192 if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
193 ret = btrfs_next_leaf(root, path);
197 goto copy_inline_extent;
199 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
200 if (key.objectid == btrfs_ino(BTRFS_I(dst)) &&
201 key.type == BTRFS_EXTENT_DATA_KEY) {
203 * There's an implicit hole at file offset 0, copy the
204 * inline extent's data to the page.
206 ASSERT(key.offset > 0);
209 } else if (i_size_read(dst) <= datal) {
210 struct btrfs_file_extent_item *ei;
212 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
213 struct btrfs_file_extent_item);
215 * If it's an inline extent replace it with the source inline
216 * extent, otherwise copy the source inline extent data into
217 * the respective page at the destination inode.
219 if (btrfs_file_extent_type(path->nodes[0], ei) ==
220 BTRFS_FILE_EXTENT_INLINE)
221 goto copy_inline_extent;
228 * We have no extent items, or we have an extent at offset 0 which may
229 * or may not be inlined. All these cases are dealt the same way.
231 if (i_size_read(dst) > datal) {
233 * At the destination offset 0 we have either a hole, a regular
234 * extent or an inline extent larger then the one we want to
235 * clone. Deal with all these cases by copying the inline extent
236 * data into the respective page at the destination inode.
242 * Release path before starting a new transaction so we don't hold locks
243 * that would confuse lockdep.
245 btrfs_release_path(path);
247 * If we end up here it means were copy the inline extent into a leaf
248 * of the destination inode. We know we will drop or adjust at most one
249 * extent item in the destination root.
251 * 1 unit - adjusting old extent (we may have to split it)
252 * 1 unit - add new extent
253 * 1 unit - inode update
255 trans = btrfs_start_transaction(root, 3);
257 ret = PTR_ERR(trans);
261 drop_args.path = path;
262 drop_args.start = drop_start;
263 drop_args.end = aligned_end;
264 drop_args.drop_cache = true;
265 ret = btrfs_drop_extents(trans, root, BTRFS_I(dst), &drop_args);
268 ret = btrfs_insert_empty_item(trans, root, path, new_key, size);
272 write_extent_buffer(path->nodes[0], inline_data,
273 btrfs_item_ptr_offset(path->nodes[0],
276 btrfs_update_inode_bytes(BTRFS_I(dst), datal, drop_args.bytes_found);
277 btrfs_set_inode_full_sync(BTRFS_I(dst));
278 ret = btrfs_inode_set_file_extent_range(BTRFS_I(dst), 0, aligned_end);
280 if (!ret && !trans) {
282 * No transaction here means we copied the inline extent into a
283 * page of the destination inode.
285 * 1 unit to update inode item
287 trans = btrfs_start_transaction(root, 1);
289 ret = PTR_ERR(trans);
294 btrfs_abort_transaction(trans, ret);
295 btrfs_end_transaction(trans);
304 * Release our path because we don't need it anymore and also because
305 * copy_inline_to_page() needs to reserve data and metadata, which may
306 * need to flush delalloc when we are low on available space and
307 * therefore cause a deadlock if writeback of an inline extent needs to
308 * write to the same leaf or an ordered extent completion needs to write
311 btrfs_release_path(path);
313 ret = copy_inline_to_page(BTRFS_I(dst), new_key->offset,
314 inline_data, size, datal, comp_type);
319 * btrfs_clone() - clone a range from inode file to another
321 * @src: Inode to clone from
322 * @inode: Inode to clone to
323 * @off: Offset within source to start clone from
324 * @olen: Original length, passed by user, of range to clone
325 * @olen_aligned: Block-aligned value of olen
326 * @destoff: Offset within @inode to start clone
327 * @no_time_update: Whether to update mtime/ctime on the target inode
329 static int btrfs_clone(struct inode *src, struct inode *inode,
330 const u64 off, const u64 olen, const u64 olen_aligned,
331 const u64 destoff, int no_time_update)
333 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
334 struct btrfs_path *path = NULL;
335 struct extent_buffer *leaf;
336 struct btrfs_trans_handle *trans;
338 struct btrfs_key key;
342 const u64 len = olen_aligned;
343 u64 last_dest_end = destoff;
344 u64 prev_extent_end = off;
347 buf = kvmalloc(fs_info->nodesize, GFP_KERNEL);
351 path = btrfs_alloc_path();
357 path->reada = READA_FORWARD;
359 key.objectid = btrfs_ino(BTRFS_I(src));
360 key.type = BTRFS_EXTENT_DATA_KEY;
364 struct btrfs_file_extent_item *extent;
368 struct btrfs_key new_key;
369 u64 disko = 0, diskl = 0;
370 u64 datao = 0, datal = 0;
374 /* Note the key will change type as we walk through the tree */
375 ret = btrfs_search_slot(NULL, BTRFS_I(src)->root, &key, path,
380 * First search, if no extent item that starts at offset off was
381 * found but the previous item is an extent item, it's possible
382 * it might overlap our target range, therefore process it.
384 if (key.offset == off && ret > 0 && path->slots[0] > 0) {
385 btrfs_item_key_to_cpu(path->nodes[0], &key,
387 if (key.type == BTRFS_EXTENT_DATA_KEY)
391 nritems = btrfs_header_nritems(path->nodes[0]);
393 if (path->slots[0] >= nritems) {
394 ret = btrfs_next_leaf(BTRFS_I(src)->root, path);
399 nritems = btrfs_header_nritems(path->nodes[0]);
401 leaf = path->nodes[0];
402 slot = path->slots[0];
404 btrfs_item_key_to_cpu(leaf, &key, slot);
405 if (key.type > BTRFS_EXTENT_DATA_KEY ||
406 key.objectid != btrfs_ino(BTRFS_I(src)))
409 ASSERT(key.type == BTRFS_EXTENT_DATA_KEY);
411 extent = btrfs_item_ptr(leaf, slot,
412 struct btrfs_file_extent_item);
413 extent_gen = btrfs_file_extent_generation(leaf, extent);
414 comp = btrfs_file_extent_compression(leaf, extent);
415 type = btrfs_file_extent_type(leaf, extent);
416 if (type == BTRFS_FILE_EXTENT_REG ||
417 type == BTRFS_FILE_EXTENT_PREALLOC) {
418 disko = btrfs_file_extent_disk_bytenr(leaf, extent);
419 diskl = btrfs_file_extent_disk_num_bytes(leaf, extent);
420 datao = btrfs_file_extent_offset(leaf, extent);
421 datal = btrfs_file_extent_num_bytes(leaf, extent);
422 } else if (type == BTRFS_FILE_EXTENT_INLINE) {
423 /* Take upper bound, may be compressed */
424 datal = btrfs_file_extent_ram_bytes(leaf, extent);
428 * The first search might have left us at an extent item that
429 * ends before our target range's start, can happen if we have
430 * holes and NO_HOLES feature enabled.
432 * Subsequent searches may leave us on a file range we have
433 * processed before - this happens due to a race with ordered
434 * extent completion for a file range that is outside our source
435 * range, but that range was part of a file extent item that
436 * also covered a leading part of our source range.
438 if (key.offset + datal <= prev_extent_end) {
441 } else if (key.offset >= off + len) {
445 prev_extent_end = key.offset + datal;
446 size = btrfs_item_size(leaf, slot);
447 read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf, slot),
450 btrfs_release_path(path);
452 memcpy(&new_key, &key, sizeof(new_key));
453 new_key.objectid = btrfs_ino(BTRFS_I(inode));
454 if (off <= key.offset)
455 new_key.offset = key.offset + destoff - off;
457 new_key.offset = destoff;
460 * Deal with a hole that doesn't have an extent item that
461 * represents it (NO_HOLES feature enabled).
462 * This hole is either in the middle of the cloning range or at
463 * the beginning (fully overlaps it or partially overlaps it).
465 if (new_key.offset != last_dest_end)
466 drop_start = last_dest_end;
468 drop_start = new_key.offset;
470 if (type == BTRFS_FILE_EXTENT_REG ||
471 type == BTRFS_FILE_EXTENT_PREALLOC) {
472 struct btrfs_replace_extent_info clone_info;
475 * a | --- range to clone ---| b
476 * | ------------- extent ------------- |
479 /* Subtract range b */
480 if (key.offset + datal > off + len)
481 datal = off + len - key.offset;
483 /* Subtract range a */
484 if (off > key.offset) {
485 datao += off - key.offset;
486 datal -= off - key.offset;
489 clone_info.disk_offset = disko;
490 clone_info.disk_len = diskl;
491 clone_info.data_offset = datao;
492 clone_info.data_len = datal;
493 clone_info.file_offset = new_key.offset;
494 clone_info.extent_buf = buf;
495 clone_info.is_new_extent = false;
496 clone_info.update_times = !no_time_update;
497 ret = btrfs_replace_file_extents(BTRFS_I(inode), path,
498 drop_start, new_key.offset + datal - 1,
499 &clone_info, &trans);
503 ASSERT(type == BTRFS_FILE_EXTENT_INLINE);
505 * Inline extents always have to start at file offset 0
506 * and can never be bigger then the sector size. We can
507 * never clone only parts of an inline extent, since all
508 * reflink operations must start at a sector size aligned
509 * offset, and the length must be aligned too or end at
510 * the i_size (which implies the whole inlined data).
512 ASSERT(key.offset == 0);
513 ASSERT(datal <= fs_info->sectorsize);
514 if (WARN_ON(type != BTRFS_FILE_EXTENT_INLINE) ||
515 WARN_ON(key.offset != 0) ||
516 WARN_ON(datal > fs_info->sectorsize)) {
521 ret = clone_copy_inline_extent(inode, path, &new_key,
522 drop_start, datal, size,
528 btrfs_release_path(path);
531 * Whenever we share an extent we update the last_reflink_trans
532 * of each inode to the current transaction. This is needed to
533 * make sure fsync does not log multiple checksum items with
534 * overlapping ranges (because some extent items might refer
535 * only to sections of the original extent). For the destination
536 * inode we do this regardless of the generation of the extents
537 * or even if they are inline extents or explicit holes, to make
538 * sure a full fsync does not skip them. For the source inode,
539 * we only need to update last_reflink_trans in case it's a new
540 * extent that is not a hole or an inline extent, to deal with
541 * the checksums problem on fsync.
543 if (extent_gen == trans->transid && disko > 0)
544 BTRFS_I(src)->last_reflink_trans = trans->transid;
546 BTRFS_I(inode)->last_reflink_trans = trans->transid;
548 last_dest_end = ALIGN(new_key.offset + datal,
549 fs_info->sectorsize);
550 ret = clone_finish_inode_update(trans, inode, last_dest_end,
551 destoff, olen, no_time_update);
554 if (new_key.offset + datal >= destoff + len)
557 btrfs_release_path(path);
558 key.offset = prev_extent_end;
560 if (fatal_signal_pending(current)) {
569 if (last_dest_end < destoff + len) {
571 * We have an implicit hole that fully or partially overlaps our
572 * cloning range at its end. This means that we either have the
573 * NO_HOLES feature enabled or the implicit hole happened due to
574 * mixing buffered and direct IO writes against this file.
576 btrfs_release_path(path);
579 * When using NO_HOLES and we are cloning a range that covers
580 * only a hole (no extents) into a range beyond the current
581 * i_size, punching a hole in the target range will not create
582 * an extent map defining a hole, because the range starts at or
583 * beyond current i_size. If the file previously had an i_size
584 * greater than the new i_size set by this clone operation, we
585 * need to make sure the next fsync is a full fsync, so that it
586 * detects and logs a hole covering a range from the current
587 * i_size to the new i_size. If the clone range covers extents,
588 * besides a hole, then we know the full sync flag was already
589 * set by previous calls to btrfs_replace_file_extents() that
590 * replaced file extent items.
592 if (last_dest_end >= i_size_read(inode))
593 btrfs_set_inode_full_sync(BTRFS_I(inode));
595 ret = btrfs_replace_file_extents(BTRFS_I(inode), path,
596 last_dest_end, destoff + len - 1, NULL, &trans);
600 ret = clone_finish_inode_update(trans, inode, destoff + len,
601 destoff, olen, no_time_update);
605 btrfs_free_path(path);
607 clear_bit(BTRFS_INODE_NO_DELALLOC_FLUSH, &BTRFS_I(inode)->runtime_flags);
612 static void btrfs_double_extent_unlock(struct inode *inode1, u64 loff1,
613 struct inode *inode2, u64 loff2, u64 len)
615 unlock_extent(&BTRFS_I(inode1)->io_tree, loff1, loff1 + len - 1);
616 unlock_extent(&BTRFS_I(inode2)->io_tree, loff2, loff2 + len - 1);
619 static void btrfs_double_extent_lock(struct inode *inode1, u64 loff1,
620 struct inode *inode2, u64 loff2, u64 len)
622 u64 range1_end = loff1 + len - 1;
623 u64 range2_end = loff2 + len - 1;
625 if (inode1 < inode2) {
626 swap(inode1, inode2);
628 swap(range1_end, range2_end);
629 } else if (inode1 == inode2 && loff2 < loff1) {
631 swap(range1_end, range2_end);
634 lock_extent(&BTRFS_I(inode1)->io_tree, loff1, range1_end);
635 lock_extent(&BTRFS_I(inode2)->io_tree, loff2, range2_end);
637 btrfs_assert_inode_range_clean(BTRFS_I(inode1), loff1, range1_end);
638 btrfs_assert_inode_range_clean(BTRFS_I(inode2), loff2, range2_end);
641 static void btrfs_double_mmap_lock(struct inode *inode1, struct inode *inode2)
644 swap(inode1, inode2);
645 down_write(&BTRFS_I(inode1)->i_mmap_lock);
646 down_write_nested(&BTRFS_I(inode2)->i_mmap_lock, SINGLE_DEPTH_NESTING);
649 static void btrfs_double_mmap_unlock(struct inode *inode1, struct inode *inode2)
651 up_write(&BTRFS_I(inode1)->i_mmap_lock);
652 up_write(&BTRFS_I(inode2)->i_mmap_lock);
655 static int btrfs_extent_same_range(struct inode *src, u64 loff, u64 len,
656 struct inode *dst, u64 dst_loff)
658 const u64 bs = BTRFS_I(src)->root->fs_info->sb->s_blocksize;
662 * Lock destination range to serialize with concurrent readahead() and
663 * source range to serialize with relocation.
665 btrfs_double_extent_lock(src, loff, dst, dst_loff, len);
666 ret = btrfs_clone(src, dst, loff, len, ALIGN(len, bs), dst_loff, 1);
667 btrfs_double_extent_unlock(src, loff, dst, dst_loff, len);
672 static int btrfs_extent_same(struct inode *src, u64 loff, u64 olen,
673 struct inode *dst, u64 dst_loff)
676 u64 i, tail_len, chunk_count;
677 struct btrfs_root *root_dst = BTRFS_I(dst)->root;
679 spin_lock(&root_dst->root_item_lock);
680 if (root_dst->send_in_progress) {
681 btrfs_warn_rl(root_dst->fs_info,
682 "cannot deduplicate to root %llu while send operations are using it (%d in progress)",
683 root_dst->root_key.objectid,
684 root_dst->send_in_progress);
685 spin_unlock(&root_dst->root_item_lock);
688 root_dst->dedupe_in_progress++;
689 spin_unlock(&root_dst->root_item_lock);
691 tail_len = olen % BTRFS_MAX_DEDUPE_LEN;
692 chunk_count = div_u64(olen, BTRFS_MAX_DEDUPE_LEN);
694 for (i = 0; i < chunk_count; i++) {
695 ret = btrfs_extent_same_range(src, loff, BTRFS_MAX_DEDUPE_LEN,
700 loff += BTRFS_MAX_DEDUPE_LEN;
701 dst_loff += BTRFS_MAX_DEDUPE_LEN;
705 ret = btrfs_extent_same_range(src, loff, tail_len, dst, dst_loff);
707 spin_lock(&root_dst->root_item_lock);
708 root_dst->dedupe_in_progress--;
709 spin_unlock(&root_dst->root_item_lock);
714 static noinline int btrfs_clone_files(struct file *file, struct file *file_src,
715 u64 off, u64 olen, u64 destoff)
717 struct inode *inode = file_inode(file);
718 struct inode *src = file_inode(file_src);
719 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
723 u64 bs = fs_info->sb->s_blocksize;
726 * VFS's generic_remap_file_range_prep() protects us from cloning the
727 * eof block into the middle of a file, which would result in corruption
728 * if the file size is not blocksize aligned. So we don't need to check
729 * for that case here.
731 if (off + len == src->i_size)
732 len = ALIGN(src->i_size, bs) - off;
734 if (destoff > inode->i_size) {
735 const u64 wb_start = ALIGN_DOWN(inode->i_size, bs);
737 ret = btrfs_cont_expand(BTRFS_I(inode), inode->i_size, destoff);
741 * We may have truncated the last block if the inode's size is
742 * not sector size aligned, so we need to wait for writeback to
743 * complete before proceeding further, otherwise we can race
744 * with cloning and attempt to increment a reference to an
745 * extent that no longer exists (writeback completed right after
746 * we found the previous extent covering eof and before we
747 * attempted to increment its reference count).
749 ret = btrfs_wait_ordered_range(inode, wb_start,
756 * Lock destination range to serialize with concurrent readahead() and
757 * source range to serialize with relocation.
759 btrfs_double_extent_lock(src, off, inode, destoff, len);
760 ret = btrfs_clone(src, inode, off, olen, len, destoff, 0);
761 btrfs_double_extent_unlock(src, off, inode, destoff, len);
764 * We may have copied an inline extent into a page of the destination
765 * range, so wait for writeback to complete before truncating pages
766 * from the page cache. This is a rare case.
768 wb_ret = btrfs_wait_ordered_range(inode, destoff, len);
769 ret = ret ? ret : wb_ret;
771 * Truncate page cache pages so that future reads will see the cloned
772 * data immediately and not the previous data.
774 truncate_inode_pages_range(&inode->i_data,
775 round_down(destoff, PAGE_SIZE),
776 round_up(destoff + len, PAGE_SIZE) - 1);
781 static int btrfs_remap_file_range_prep(struct file *file_in, loff_t pos_in,
782 struct file *file_out, loff_t pos_out,
783 loff_t *len, unsigned int remap_flags)
785 struct inode *inode_in = file_inode(file_in);
786 struct inode *inode_out = file_inode(file_out);
787 u64 bs = BTRFS_I(inode_out)->root->fs_info->sb->s_blocksize;
791 if (!(remap_flags & REMAP_FILE_DEDUP)) {
792 struct btrfs_root *root_out = BTRFS_I(inode_out)->root;
794 if (btrfs_root_readonly(root_out))
797 ASSERT(inode_in->i_sb == inode_out->i_sb);
800 /* Don't make the dst file partly checksummed */
801 if ((BTRFS_I(inode_in)->flags & BTRFS_INODE_NODATASUM) !=
802 (BTRFS_I(inode_out)->flags & BTRFS_INODE_NODATASUM)) {
807 * Now that the inodes are locked, we need to start writeback ourselves
808 * and can not rely on the writeback from the VFS's generic helper
809 * generic_remap_file_range_prep() because:
811 * 1) For compression we must call filemap_fdatawrite_range() range
812 * twice (btrfs_fdatawrite_range() does it for us), and the generic
813 * helper only calls it once;
815 * 2) filemap_fdatawrite_range(), called by the generic helper only
816 * waits for the writeback to complete, i.e. for IO to be done, and
817 * not for the ordered extents to complete. We need to wait for them
818 * to complete so that new file extent items are in the fs tree.
820 if (*len == 0 && !(remap_flags & REMAP_FILE_DEDUP))
821 wb_len = ALIGN(inode_in->i_size, bs) - ALIGN_DOWN(pos_in, bs);
823 wb_len = ALIGN(*len, bs);
826 * Workaround to make sure NOCOW buffered write reach disk as NOCOW.
828 * Btrfs' back references do not have a block level granularity, they
829 * work at the whole extent level.
830 * NOCOW buffered write without data space reserved may not be able
831 * to fall back to CoW due to lack of data space, thus could cause
834 * Here we take a shortcut by flushing the whole inode, so that all
835 * nocow write should reach disk as nocow before we increase the
836 * reference of the extent. We could do better by only flushing NOCOW
837 * data, but that needs extra accounting.
839 * Also we don't need to check ASYNC_EXTENT, as async extent will be
840 * CoWed anyway, not affecting nocow part.
842 ret = filemap_flush(inode_in->i_mapping);
846 ret = btrfs_wait_ordered_range(inode_in, ALIGN_DOWN(pos_in, bs),
850 ret = btrfs_wait_ordered_range(inode_out, ALIGN_DOWN(pos_out, bs),
855 return generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out,
859 static bool file_sync_write(const struct file *file)
861 if (file->f_flags & (__O_SYNC | O_DSYNC))
863 if (IS_SYNC(file_inode(file)))
869 loff_t btrfs_remap_file_range(struct file *src_file, loff_t off,
870 struct file *dst_file, loff_t destoff, loff_t len,
871 unsigned int remap_flags)
873 struct inode *src_inode = file_inode(src_file);
874 struct inode *dst_inode = file_inode(dst_file);
875 bool same_inode = dst_inode == src_inode;
878 if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY))
882 btrfs_inode_lock(src_inode, BTRFS_ILOCK_MMAP);
884 lock_two_nondirectories(src_inode, dst_inode);
885 btrfs_double_mmap_lock(src_inode, dst_inode);
888 ret = btrfs_remap_file_range_prep(src_file, off, dst_file, destoff,
890 if (ret < 0 || len == 0)
893 if (remap_flags & REMAP_FILE_DEDUP)
894 ret = btrfs_extent_same(src_inode, off, len, dst_inode, destoff);
896 ret = btrfs_clone_files(dst_file, src_file, off, len, destoff);
900 btrfs_inode_unlock(src_inode, BTRFS_ILOCK_MMAP);
902 btrfs_double_mmap_unlock(src_inode, dst_inode);
903 unlock_two_nondirectories(src_inode, dst_inode);
907 * If either the source or the destination file was opened with O_SYNC,
908 * O_DSYNC or has the S_SYNC attribute, fsync both the destination and
909 * source files/ranges, so that after a successful return (0) followed
910 * by a power failure results in the reflinked data to be readable from
913 if (ret == 0 && len > 0 &&
914 (file_sync_write(src_file) || file_sync_write(dst_file))) {
915 ret = btrfs_sync_file(src_file, off, off + len - 1, 0);
917 ret = btrfs_sync_file(dst_file, destoff,
918 destoff + len - 1, 0);
921 return ret < 0 ? ret : len;