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"
11 #define BTRFS_MAX_DEDUPE_LEN SZ_16M
13 static int clone_finish_inode_update(struct btrfs_trans_handle *trans,
20 struct btrfs_root *root = BTRFS_I(inode)->root;
23 inode_inc_iversion(inode);
25 inode->i_mtime = inode->i_ctime = current_time(inode);
27 * We round up to the block size at eof when determining which
28 * extents to clone above, but shouldn't round up the file size.
30 if (endoff > destoff + olen)
31 endoff = destoff + olen;
32 if (endoff > inode->i_size) {
33 i_size_write(inode, endoff);
34 btrfs_inode_safe_disk_i_size_write(BTRFS_I(inode), 0);
37 ret = btrfs_update_inode(trans, root, BTRFS_I(inode));
39 btrfs_abort_transaction(trans, ret);
40 btrfs_end_transaction(trans);
43 ret = btrfs_end_transaction(trans);
48 static int copy_inline_to_page(struct btrfs_inode *inode,
49 const u64 file_offset,
55 const u64 block_size = btrfs_inode_sectorsize(inode);
56 const u64 range_end = file_offset + block_size - 1;
57 const size_t inline_size = size - btrfs_file_extent_calc_inline_size(0);
58 char *data_start = inline_data + btrfs_file_extent_calc_inline_size(0);
59 struct extent_changeset *data_reserved = NULL;
60 struct page *page = NULL;
61 struct address_space *mapping = inode->vfs_inode.i_mapping;
64 ASSERT(IS_ALIGNED(file_offset, block_size));
67 * We have flushed and locked the ranges of the source and destination
68 * inodes, we also have locked the inodes, so we are safe to do a
69 * reservation here. Also we must not do the reservation while holding
70 * a transaction open, otherwise we would deadlock.
72 ret = btrfs_delalloc_reserve_space(inode, &data_reserved, file_offset,
77 page = find_or_create_page(mapping, file_offset >> PAGE_SHIFT,
78 btrfs_alloc_write_mask(mapping));
84 ret = set_page_extent_mapped(page);
88 clear_extent_bit(&inode->io_tree, file_offset, range_end,
89 EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG,
91 ret = btrfs_set_extent_delalloc(inode, file_offset, range_end, 0, NULL);
96 * After dirtying the page our caller will need to start a transaction,
97 * and if we are low on metadata free space, that can cause flushing of
98 * delalloc for all inodes in order to get metadata space released.
99 * However we are holding the range locked for the whole duration of
100 * the clone/dedupe operation, so we may deadlock if that happens and no
101 * other task releases enough space. So mark this inode as not being
102 * possible to flush to avoid such deadlock. We will clear that flag
103 * when we finish cloning all extents, since a transaction is started
104 * after finding each extent to clone.
106 set_bit(BTRFS_INODE_NO_DELALLOC_FLUSH, &inode->runtime_flags);
108 if (comp_type == BTRFS_COMPRESS_NONE) {
109 memcpy_to_page(page, 0, data_start, datal);
110 flush_dcache_page(page);
112 ret = btrfs_decompress(comp_type, data_start, page, 0,
116 flush_dcache_page(page);
120 * If our inline data is smaller then the block/page size, then the
121 * remaining of the block/page is equivalent to zeroes. We had something
122 * like the following done:
124 * $ xfs_io -f -c "pwrite -S 0xab 0 500" file
125 * $ sync # (or fsync)
126 * $ xfs_io -c "falloc 0 4K" file
127 * $ xfs_io -c "pwrite -S 0xcd 4K 4K"
129 * So what's in the range [500, 4095] corresponds to zeroes.
131 if (datal < block_size) {
135 memset(map + datal, 0, block_size - datal);
136 flush_dcache_page(page);
140 SetPageUptodate(page);
141 ClearPageChecked(page);
142 set_page_dirty(page);
149 btrfs_delalloc_release_space(inode, data_reserved, file_offset,
151 btrfs_delalloc_release_extents(inode, block_size);
153 extent_changeset_free(data_reserved);
159 * Deal with cloning of inline extents. We try to copy the inline extent from
160 * the source inode to destination inode when possible. When not possible we
161 * copy the inline extent's data into the respective page of the inode.
163 static int clone_copy_inline_extent(struct inode *dst,
164 struct btrfs_path *path,
165 struct btrfs_key *new_key,
166 const u64 drop_start,
171 struct btrfs_trans_handle **trans_out)
173 struct btrfs_fs_info *fs_info = btrfs_sb(dst->i_sb);
174 struct btrfs_root *root = BTRFS_I(dst)->root;
175 const u64 aligned_end = ALIGN(new_key->offset + datal,
176 fs_info->sectorsize);
177 struct btrfs_trans_handle *trans = NULL;
178 struct btrfs_drop_extents_args drop_args = { 0 };
180 struct btrfs_key key;
182 if (new_key->offset > 0) {
183 ret = copy_inline_to_page(BTRFS_I(dst), new_key->offset,
184 inline_data, size, datal, comp_type);
188 key.objectid = btrfs_ino(BTRFS_I(dst));
189 key.type = BTRFS_EXTENT_DATA_KEY;
191 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
194 } else if (ret > 0) {
195 if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
196 ret = btrfs_next_leaf(root, path);
200 goto copy_inline_extent;
202 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
203 if (key.objectid == btrfs_ino(BTRFS_I(dst)) &&
204 key.type == BTRFS_EXTENT_DATA_KEY) {
206 * There's an implicit hole at file offset 0, copy the
207 * inline extent's data to the page.
209 ASSERT(key.offset > 0);
210 ret = copy_inline_to_page(BTRFS_I(dst), new_key->offset,
211 inline_data, size, datal,
215 } else if (i_size_read(dst) <= datal) {
216 struct btrfs_file_extent_item *ei;
218 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
219 struct btrfs_file_extent_item);
221 * If it's an inline extent replace it with the source inline
222 * extent, otherwise copy the source inline extent data into
223 * the respective page at the destination inode.
225 if (btrfs_file_extent_type(path->nodes[0], ei) ==
226 BTRFS_FILE_EXTENT_INLINE)
227 goto copy_inline_extent;
229 ret = copy_inline_to_page(BTRFS_I(dst), new_key->offset,
230 inline_data, size, datal, comp_type);
237 * We have no extent items, or we have an extent at offset 0 which may
238 * or may not be inlined. All these cases are dealt the same way.
240 if (i_size_read(dst) > datal) {
242 * At the destination offset 0 we have either a hole, a regular
243 * extent or an inline extent larger then the one we want to
244 * clone. Deal with all these cases by copying the inline extent
245 * data into the respective page at the destination inode.
247 ret = copy_inline_to_page(BTRFS_I(dst), new_key->offset,
248 inline_data, size, datal, comp_type);
252 btrfs_release_path(path);
254 * If we end up here it means were copy the inline extent into a leaf
255 * of the destination inode. We know we will drop or adjust at most one
256 * extent item in the destination root.
258 * 1 unit - adjusting old extent (we may have to split it)
259 * 1 unit - add new extent
260 * 1 unit - inode update
262 trans = btrfs_start_transaction(root, 3);
264 ret = PTR_ERR(trans);
268 drop_args.path = path;
269 drop_args.start = drop_start;
270 drop_args.end = aligned_end;
271 drop_args.drop_cache = true;
272 ret = btrfs_drop_extents(trans, root, BTRFS_I(dst), &drop_args);
275 ret = btrfs_insert_empty_item(trans, root, path, new_key, size);
279 write_extent_buffer(path->nodes[0], inline_data,
280 btrfs_item_ptr_offset(path->nodes[0],
283 btrfs_update_inode_bytes(BTRFS_I(dst), datal, drop_args.bytes_found);
284 set_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &BTRFS_I(dst)->runtime_flags);
285 ret = btrfs_inode_set_file_extent_range(BTRFS_I(dst), 0, aligned_end);
287 if (!ret && !trans) {
289 * No transaction here means we copied the inline extent into a
290 * page of the destination inode.
292 * 1 unit to update inode item
294 trans = btrfs_start_transaction(root, 1);
296 ret = PTR_ERR(trans);
301 btrfs_abort_transaction(trans, ret);
302 btrfs_end_transaction(trans);
311 * btrfs_clone() - clone a range from inode file to another
313 * @src: Inode to clone from
314 * @inode: Inode to clone to
315 * @off: Offset within source to start clone from
316 * @olen: Original length, passed by user, of range to clone
317 * @olen_aligned: Block-aligned value of olen
318 * @destoff: Offset within @inode to start clone
319 * @no_time_update: Whether to update mtime/ctime on the target inode
321 static int btrfs_clone(struct inode *src, struct inode *inode,
322 const u64 off, const u64 olen, const u64 olen_aligned,
323 const u64 destoff, int no_time_update)
325 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
326 struct btrfs_path *path = NULL;
327 struct extent_buffer *leaf;
328 struct btrfs_trans_handle *trans;
330 struct btrfs_key key;
334 const u64 len = olen_aligned;
335 u64 last_dest_end = destoff;
338 buf = kvmalloc(fs_info->nodesize, GFP_KERNEL);
342 path = btrfs_alloc_path();
348 path->reada = READA_FORWARD;
350 key.objectid = btrfs_ino(BTRFS_I(src));
351 key.type = BTRFS_EXTENT_DATA_KEY;
355 u64 next_key_min_offset = key.offset + 1;
356 struct btrfs_file_extent_item *extent;
360 struct btrfs_key new_key;
361 u64 disko = 0, diskl = 0;
362 u64 datao = 0, datal = 0;
366 /* Note the key will change type as we walk through the tree */
367 ret = btrfs_search_slot(NULL, BTRFS_I(src)->root, &key, path,
372 * First search, if no extent item that starts at offset off was
373 * found but the previous item is an extent item, it's possible
374 * it might overlap our target range, therefore process it.
376 if (key.offset == off && ret > 0 && path->slots[0] > 0) {
377 btrfs_item_key_to_cpu(path->nodes[0], &key,
379 if (key.type == BTRFS_EXTENT_DATA_KEY)
383 nritems = btrfs_header_nritems(path->nodes[0]);
385 if (path->slots[0] >= nritems) {
386 ret = btrfs_next_leaf(BTRFS_I(src)->root, path);
391 nritems = btrfs_header_nritems(path->nodes[0]);
393 leaf = path->nodes[0];
394 slot = path->slots[0];
396 btrfs_item_key_to_cpu(leaf, &key, slot);
397 if (key.type > BTRFS_EXTENT_DATA_KEY ||
398 key.objectid != btrfs_ino(BTRFS_I(src)))
401 ASSERT(key.type == BTRFS_EXTENT_DATA_KEY);
403 extent = btrfs_item_ptr(leaf, slot,
404 struct btrfs_file_extent_item);
405 extent_gen = btrfs_file_extent_generation(leaf, extent);
406 comp = btrfs_file_extent_compression(leaf, extent);
407 type = btrfs_file_extent_type(leaf, extent);
408 if (type == BTRFS_FILE_EXTENT_REG ||
409 type == BTRFS_FILE_EXTENT_PREALLOC) {
410 disko = btrfs_file_extent_disk_bytenr(leaf, extent);
411 diskl = btrfs_file_extent_disk_num_bytes(leaf, extent);
412 datao = btrfs_file_extent_offset(leaf, extent);
413 datal = btrfs_file_extent_num_bytes(leaf, extent);
414 } else if (type == BTRFS_FILE_EXTENT_INLINE) {
415 /* Take upper bound, may be compressed */
416 datal = btrfs_file_extent_ram_bytes(leaf, extent);
420 * The first search might have left us at an extent item that
421 * ends before our target range's start, can happen if we have
422 * holes and NO_HOLES feature enabled.
424 if (key.offset + datal <= off) {
427 } else if (key.offset >= off + len) {
430 next_key_min_offset = key.offset + datal;
431 size = btrfs_item_size_nr(leaf, slot);
432 read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf, slot),
435 btrfs_release_path(path);
437 memcpy(&new_key, &key, sizeof(new_key));
438 new_key.objectid = btrfs_ino(BTRFS_I(inode));
439 if (off <= key.offset)
440 new_key.offset = key.offset + destoff - off;
442 new_key.offset = destoff;
445 * Deal with a hole that doesn't have an extent item that
446 * represents it (NO_HOLES feature enabled).
447 * This hole is either in the middle of the cloning range or at
448 * the beginning (fully overlaps it or partially overlaps it).
450 if (new_key.offset != last_dest_end)
451 drop_start = last_dest_end;
453 drop_start = new_key.offset;
455 if (type == BTRFS_FILE_EXTENT_REG ||
456 type == BTRFS_FILE_EXTENT_PREALLOC) {
457 struct btrfs_replace_extent_info clone_info;
460 * a | --- range to clone ---| b
461 * | ------------- extent ------------- |
464 /* Subtract range b */
465 if (key.offset + datal > off + len)
466 datal = off + len - key.offset;
468 /* Subtract range a */
469 if (off > key.offset) {
470 datao += off - key.offset;
471 datal -= off - key.offset;
474 clone_info.disk_offset = disko;
475 clone_info.disk_len = diskl;
476 clone_info.data_offset = datao;
477 clone_info.data_len = datal;
478 clone_info.file_offset = new_key.offset;
479 clone_info.extent_buf = buf;
480 clone_info.is_new_extent = false;
481 ret = btrfs_replace_file_extents(BTRFS_I(inode), path,
482 drop_start, new_key.offset + datal - 1,
483 &clone_info, &trans);
486 } else if (type == BTRFS_FILE_EXTENT_INLINE) {
488 * Inline extents always have to start at file offset 0
489 * and can never be bigger then the sector size. We can
490 * never clone only parts of an inline extent, since all
491 * reflink operations must start at a sector size aligned
492 * offset, and the length must be aligned too or end at
493 * the i_size (which implies the whole inlined data).
495 ASSERT(key.offset == 0);
496 ASSERT(datal <= fs_info->sectorsize);
497 if (key.offset != 0 || datal > fs_info->sectorsize)
500 ret = clone_copy_inline_extent(inode, path, &new_key,
501 drop_start, datal, size,
507 btrfs_release_path(path);
510 * If this is a new extent update the last_reflink_trans of both
511 * inodes. This is used by fsync to make sure it does not log
512 * multiple checksum items with overlapping ranges. For older
513 * extents we don't need to do it since inode logging skips the
514 * checksums for older extents. Also ignore holes and inline
515 * extents because they don't have checksums in the csum tree.
517 if (extent_gen == trans->transid && disko > 0) {
518 BTRFS_I(src)->last_reflink_trans = trans->transid;
519 BTRFS_I(inode)->last_reflink_trans = trans->transid;
522 last_dest_end = ALIGN(new_key.offset + datal,
523 fs_info->sectorsize);
524 ret = clone_finish_inode_update(trans, inode, last_dest_end,
525 destoff, olen, no_time_update);
528 if (new_key.offset + datal >= destoff + len)
531 btrfs_release_path(path);
532 key.offset = next_key_min_offset;
534 if (fatal_signal_pending(current)) {
543 if (last_dest_end < destoff + len) {
545 * We have an implicit hole that fully or partially overlaps our
546 * cloning range at its end. This means that we either have the
547 * NO_HOLES feature enabled or the implicit hole happened due to
548 * mixing buffered and direct IO writes against this file.
550 btrfs_release_path(path);
553 * When using NO_HOLES and we are cloning a range that covers
554 * only a hole (no extents) into a range beyond the current
555 * i_size, punching a hole in the target range will not create
556 * an extent map defining a hole, because the range starts at or
557 * beyond current i_size. If the file previously had an i_size
558 * greater than the new i_size set by this clone operation, we
559 * need to make sure the next fsync is a full fsync, so that it
560 * detects and logs a hole covering a range from the current
561 * i_size to the new i_size. If the clone range covers extents,
562 * besides a hole, then we know the full sync flag was already
563 * set by previous calls to btrfs_replace_file_extents() that
564 * replaced file extent items.
566 if (last_dest_end >= i_size_read(inode))
567 set_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
568 &BTRFS_I(inode)->runtime_flags);
570 ret = btrfs_replace_file_extents(BTRFS_I(inode), path,
571 last_dest_end, destoff + len - 1, NULL, &trans);
575 ret = clone_finish_inode_update(trans, inode, destoff + len,
576 destoff, olen, no_time_update);
580 btrfs_free_path(path);
582 clear_bit(BTRFS_INODE_NO_DELALLOC_FLUSH, &BTRFS_I(inode)->runtime_flags);
587 static void btrfs_double_extent_unlock(struct inode *inode1, u64 loff1,
588 struct inode *inode2, u64 loff2, u64 len)
590 unlock_extent(&BTRFS_I(inode1)->io_tree, loff1, loff1 + len - 1);
591 unlock_extent(&BTRFS_I(inode2)->io_tree, loff2, loff2 + len - 1);
594 static void btrfs_double_extent_lock(struct inode *inode1, u64 loff1,
595 struct inode *inode2, u64 loff2, u64 len)
597 if (inode1 < inode2) {
598 swap(inode1, inode2);
600 } else if (inode1 == inode2 && loff2 < loff1) {
603 lock_extent(&BTRFS_I(inode1)->io_tree, loff1, loff1 + len - 1);
604 lock_extent(&BTRFS_I(inode2)->io_tree, loff2, loff2 + len - 1);
607 static void btrfs_double_mmap_lock(struct inode *inode1, struct inode *inode2)
610 swap(inode1, inode2);
611 down_write(&BTRFS_I(inode1)->i_mmap_lock);
612 down_write_nested(&BTRFS_I(inode2)->i_mmap_lock, SINGLE_DEPTH_NESTING);
615 static void btrfs_double_mmap_unlock(struct inode *inode1, struct inode *inode2)
617 up_write(&BTRFS_I(inode1)->i_mmap_lock);
618 up_write(&BTRFS_I(inode2)->i_mmap_lock);
621 static int btrfs_extent_same_range(struct inode *src, u64 loff, u64 len,
622 struct inode *dst, u64 dst_loff)
624 const u64 bs = BTRFS_I(src)->root->fs_info->sb->s_blocksize;
628 * Lock destination range to serialize with concurrent readpages() and
629 * source range to serialize with relocation.
631 btrfs_double_extent_lock(src, loff, dst, dst_loff, len);
632 ret = btrfs_clone(src, dst, loff, len, ALIGN(len, bs), dst_loff, 1);
633 btrfs_double_extent_unlock(src, loff, dst, dst_loff, len);
638 static int btrfs_extent_same(struct inode *src, u64 loff, u64 olen,
639 struct inode *dst, u64 dst_loff)
642 u64 i, tail_len, chunk_count;
643 struct btrfs_root *root_dst = BTRFS_I(dst)->root;
645 spin_lock(&root_dst->root_item_lock);
646 if (root_dst->send_in_progress) {
647 btrfs_warn_rl(root_dst->fs_info,
648 "cannot deduplicate to root %llu while send operations are using it (%d in progress)",
649 root_dst->root_key.objectid,
650 root_dst->send_in_progress);
651 spin_unlock(&root_dst->root_item_lock);
654 root_dst->dedupe_in_progress++;
655 spin_unlock(&root_dst->root_item_lock);
657 tail_len = olen % BTRFS_MAX_DEDUPE_LEN;
658 chunk_count = div_u64(olen, BTRFS_MAX_DEDUPE_LEN);
660 for (i = 0; i < chunk_count; i++) {
661 ret = btrfs_extent_same_range(src, loff, BTRFS_MAX_DEDUPE_LEN,
666 loff += BTRFS_MAX_DEDUPE_LEN;
667 dst_loff += BTRFS_MAX_DEDUPE_LEN;
671 ret = btrfs_extent_same_range(src, loff, tail_len, dst, dst_loff);
673 spin_lock(&root_dst->root_item_lock);
674 root_dst->dedupe_in_progress--;
675 spin_unlock(&root_dst->root_item_lock);
680 static noinline int btrfs_clone_files(struct file *file, struct file *file_src,
681 u64 off, u64 olen, u64 destoff)
683 struct inode *inode = file_inode(file);
684 struct inode *src = file_inode(file_src);
685 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
689 u64 bs = fs_info->sb->s_blocksize;
692 * VFS's generic_remap_file_range_prep() protects us from cloning the
693 * eof block into the middle of a file, which would result in corruption
694 * if the file size is not blocksize aligned. So we don't need to check
695 * for that case here.
697 if (off + len == src->i_size)
698 len = ALIGN(src->i_size, bs) - off;
700 if (destoff > inode->i_size) {
701 const u64 wb_start = ALIGN_DOWN(inode->i_size, bs);
703 ret = btrfs_cont_expand(BTRFS_I(inode), inode->i_size, destoff);
707 * We may have truncated the last block if the inode's size is
708 * not sector size aligned, so we need to wait for writeback to
709 * complete before proceeding further, otherwise we can race
710 * with cloning and attempt to increment a reference to an
711 * extent that no longer exists (writeback completed right after
712 * we found the previous extent covering eof and before we
713 * attempted to increment its reference count).
715 ret = btrfs_wait_ordered_range(inode, wb_start,
722 * Lock destination range to serialize with concurrent readpages() and
723 * source range to serialize with relocation.
725 btrfs_double_extent_lock(src, off, inode, destoff, len);
726 ret = btrfs_clone(src, inode, off, olen, len, destoff, 0);
727 btrfs_double_extent_unlock(src, off, inode, destoff, len);
730 * We may have copied an inline extent into a page of the destination
731 * range, so wait for writeback to complete before truncating pages
732 * from the page cache. This is a rare case.
734 wb_ret = btrfs_wait_ordered_range(inode, destoff, len);
735 ret = ret ? ret : wb_ret;
737 * Truncate page cache pages so that future reads will see the cloned
738 * data immediately and not the previous data.
740 truncate_inode_pages_range(&inode->i_data,
741 round_down(destoff, PAGE_SIZE),
742 round_up(destoff + len, PAGE_SIZE) - 1);
747 static int btrfs_remap_file_range_prep(struct file *file_in, loff_t pos_in,
748 struct file *file_out, loff_t pos_out,
749 loff_t *len, unsigned int remap_flags)
751 struct inode *inode_in = file_inode(file_in);
752 struct inode *inode_out = file_inode(file_out);
753 u64 bs = BTRFS_I(inode_out)->root->fs_info->sb->s_blocksize;
754 bool same_inode = inode_out == inode_in;
758 if (!(remap_flags & REMAP_FILE_DEDUP)) {
759 struct btrfs_root *root_out = BTRFS_I(inode_out)->root;
761 if (btrfs_root_readonly(root_out))
764 if (file_in->f_path.mnt != file_out->f_path.mnt ||
765 inode_in->i_sb != inode_out->i_sb)
769 /* Don't make the dst file partly checksummed */
770 if ((BTRFS_I(inode_in)->flags & BTRFS_INODE_NODATASUM) !=
771 (BTRFS_I(inode_out)->flags & BTRFS_INODE_NODATASUM)) {
776 * Now that the inodes are locked, we need to start writeback ourselves
777 * and can not rely on the writeback from the VFS's generic helper
778 * generic_remap_file_range_prep() because:
780 * 1) For compression we must call filemap_fdatawrite_range() range
781 * twice (btrfs_fdatawrite_range() does it for us), and the generic
782 * helper only calls it once;
784 * 2) filemap_fdatawrite_range(), called by the generic helper only
785 * waits for the writeback to complete, i.e. for IO to be done, and
786 * not for the ordered extents to complete. We need to wait for them
787 * to complete so that new file extent items are in the fs tree.
789 if (*len == 0 && !(remap_flags & REMAP_FILE_DEDUP))
790 wb_len = ALIGN(inode_in->i_size, bs) - ALIGN_DOWN(pos_in, bs);
792 wb_len = ALIGN(*len, bs);
795 * Since we don't lock ranges, wait for ongoing lockless dio writes (as
796 * any in progress could create its ordered extents after we wait for
797 * existing ordered extents below).
799 inode_dio_wait(inode_in);
801 inode_dio_wait(inode_out);
804 * Workaround to make sure NOCOW buffered write reach disk as NOCOW.
806 * Btrfs' back references do not have a block level granularity, they
807 * work at the whole extent level.
808 * NOCOW buffered write without data space reserved may not be able
809 * to fall back to CoW due to lack of data space, thus could cause
812 * Here we take a shortcut by flushing the whole inode, so that all
813 * nocow write should reach disk as nocow before we increase the
814 * reference of the extent. We could do better by only flushing NOCOW
815 * data, but that needs extra accounting.
817 * Also we don't need to check ASYNC_EXTENT, as async extent will be
818 * CoWed anyway, not affecting nocow part.
820 ret = filemap_flush(inode_in->i_mapping);
824 ret = btrfs_wait_ordered_range(inode_in, ALIGN_DOWN(pos_in, bs),
828 ret = btrfs_wait_ordered_range(inode_out, ALIGN_DOWN(pos_out, bs),
833 return generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out,
837 static bool file_sync_write(const struct file *file)
839 if (file->f_flags & (__O_SYNC | O_DSYNC))
841 if (IS_SYNC(file_inode(file)))
847 loff_t btrfs_remap_file_range(struct file *src_file, loff_t off,
848 struct file *dst_file, loff_t destoff, loff_t len,
849 unsigned int remap_flags)
851 struct inode *src_inode = file_inode(src_file);
852 struct inode *dst_inode = file_inode(dst_file);
853 bool same_inode = dst_inode == src_inode;
856 if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY))
860 btrfs_inode_lock(src_inode, BTRFS_ILOCK_MMAP);
862 lock_two_nondirectories(src_inode, dst_inode);
863 btrfs_double_mmap_lock(src_inode, dst_inode);
866 ret = btrfs_remap_file_range_prep(src_file, off, dst_file, destoff,
868 if (ret < 0 || len == 0)
871 if (remap_flags & REMAP_FILE_DEDUP)
872 ret = btrfs_extent_same(src_inode, off, len, dst_inode, destoff);
874 ret = btrfs_clone_files(dst_file, src_file, off, len, destoff);
878 btrfs_inode_unlock(src_inode, BTRFS_ILOCK_MMAP);
880 btrfs_double_mmap_unlock(src_inode, dst_inode);
881 unlock_two_nondirectories(src_inode, dst_inode);
885 * If either the source or the destination file was opened with O_SYNC,
886 * O_DSYNC or has the S_SYNC attribute, fsync both the destination and
887 * source files/ranges, so that after a successful return (0) followed
888 * by a power failure results in the reflinked data to be readable from
891 if (ret == 0 && len > 0 &&
892 (file_sync_write(src_file) || file_sync_write(dst_file))) {
893 ret = btrfs_sync_file(src_file, off, off + len - 1, 0);
895 ret = btrfs_sync_file(dst_file, destoff,
896 destoff + len - 1, 0);
899 return ret < 0 ? ret : len;