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 set_page_extent_mapped(page
);
85 clear_extent_bit(&inode
->io_tree
, file_offset
, range_end
,
86 EXTENT_DELALLOC
| EXTENT_DO_ACCOUNTING
| EXTENT_DEFRAG
,
88 ret
= btrfs_set_extent_delalloc(inode
, file_offset
, range_end
, 0, NULL
);
92 if (comp_type
== BTRFS_COMPRESS_NONE
) {
96 memcpy(map
, data_start
, datal
);
97 flush_dcache_page(page
);
100 ret
= btrfs_decompress(comp_type
, data_start
, page
, 0,
104 flush_dcache_page(page
);
108 * If our inline data is smaller then the block/page size, then the
109 * remaining of the block/page is equivalent to zeroes. We had something
110 * like the following done:
112 * $ xfs_io -f -c "pwrite -S 0xab 0 500" file
113 * $ sync # (or fsync)
114 * $ xfs_io -c "falloc 0 4K" file
115 * $ xfs_io -c "pwrite -S 0xcd 4K 4K"
117 * So what's in the range [500, 4095] corresponds to zeroes.
119 if (datal
< block_size
) {
123 memset(map
+ datal
, 0, block_size
- datal
);
124 flush_dcache_page(page
);
128 SetPageUptodate(page
);
129 ClearPageChecked(page
);
130 set_page_dirty(page
);
137 btrfs_delalloc_release_space(inode
, data_reserved
, file_offset
,
139 btrfs_delalloc_release_extents(inode
, block_size
);
141 extent_changeset_free(data_reserved
);
147 * Deal with cloning of inline extents. We try to copy the inline extent from
148 * the source inode to destination inode when possible. When not possible we
149 * copy the inline extent's data into the respective page of the inode.
151 static int clone_copy_inline_extent(struct inode
*dst
,
152 struct btrfs_path
*path
,
153 struct btrfs_key
*new_key
,
154 const u64 drop_start
,
159 struct btrfs_trans_handle
**trans_out
)
161 struct btrfs_fs_info
*fs_info
= btrfs_sb(dst
->i_sb
);
162 struct btrfs_root
*root
= BTRFS_I(dst
)->root
;
163 const u64 aligned_end
= ALIGN(new_key
->offset
+ datal
,
164 fs_info
->sectorsize
);
165 struct btrfs_trans_handle
*trans
= NULL
;
166 struct btrfs_drop_extents_args drop_args
= { 0 };
168 struct btrfs_key key
;
170 if (new_key
->offset
> 0) {
171 ret
= copy_inline_to_page(BTRFS_I(dst
), new_key
->offset
,
172 inline_data
, size
, datal
, comp_type
);
176 key
.objectid
= btrfs_ino(BTRFS_I(dst
));
177 key
.type
= BTRFS_EXTENT_DATA_KEY
;
179 ret
= btrfs_search_slot(NULL
, root
, &key
, path
, 0, 0);
182 } else if (ret
> 0) {
183 if (path
->slots
[0] >= btrfs_header_nritems(path
->nodes
[0])) {
184 ret
= btrfs_next_leaf(root
, path
);
188 goto copy_inline_extent
;
190 btrfs_item_key_to_cpu(path
->nodes
[0], &key
, path
->slots
[0]);
191 if (key
.objectid
== btrfs_ino(BTRFS_I(dst
)) &&
192 key
.type
== BTRFS_EXTENT_DATA_KEY
) {
194 * There's an implicit hole at file offset 0, copy the
195 * inline extent's data to the page.
197 ASSERT(key
.offset
> 0);
198 ret
= copy_inline_to_page(BTRFS_I(dst
), new_key
->offset
,
199 inline_data
, size
, datal
,
203 } else if (i_size_read(dst
) <= datal
) {
204 struct btrfs_file_extent_item
*ei
;
206 ei
= btrfs_item_ptr(path
->nodes
[0], path
->slots
[0],
207 struct btrfs_file_extent_item
);
209 * If it's an inline extent replace it with the source inline
210 * extent, otherwise copy the source inline extent data into
211 * the respective page at the destination inode.
213 if (btrfs_file_extent_type(path
->nodes
[0], ei
) ==
214 BTRFS_FILE_EXTENT_INLINE
)
215 goto copy_inline_extent
;
217 ret
= copy_inline_to_page(BTRFS_I(dst
), new_key
->offset
,
218 inline_data
, size
, datal
, comp_type
);
225 * We have no extent items, or we have an extent at offset 0 which may
226 * or may not be inlined. All these cases are dealt the same way.
228 if (i_size_read(dst
) > datal
) {
230 * At the destination offset 0 we have either a hole, a regular
231 * extent or an inline extent larger then the one we want to
232 * clone. Deal with all these cases by copying the inline extent
233 * data into the respective page at the destination inode.
235 ret
= copy_inline_to_page(BTRFS_I(dst
), new_key
->offset
,
236 inline_data
, size
, datal
, comp_type
);
240 btrfs_release_path(path
);
242 * If we end up here it means were copy the inline extent into a leaf
243 * of the destination inode. We know we will drop or adjust at most one
244 * extent item in the destination root.
246 * 1 unit - adjusting old extent (we may have to split it)
247 * 1 unit - add new extent
248 * 1 unit - inode update
250 trans
= btrfs_start_transaction(root
, 3);
252 ret
= PTR_ERR(trans
);
256 drop_args
.path
= path
;
257 drop_args
.start
= drop_start
;
258 drop_args
.end
= aligned_end
;
259 drop_args
.drop_cache
= true;
260 ret
= btrfs_drop_extents(trans
, root
, BTRFS_I(dst
), &drop_args
);
263 ret
= btrfs_insert_empty_item(trans
, root
, path
, new_key
, size
);
267 write_extent_buffer(path
->nodes
[0], inline_data
,
268 btrfs_item_ptr_offset(path
->nodes
[0],
271 btrfs_update_inode_bytes(BTRFS_I(dst
), datal
, drop_args
.bytes_found
);
272 set_bit(BTRFS_INODE_NEEDS_FULL_SYNC
, &BTRFS_I(dst
)->runtime_flags
);
273 ret
= btrfs_inode_set_file_extent_range(BTRFS_I(dst
), 0, aligned_end
);
275 if (!ret
&& !trans
) {
277 * No transaction here means we copied the inline extent into a
278 * page of the destination inode.
280 * 1 unit to update inode item
282 trans
= btrfs_start_transaction(root
, 1);
284 ret
= PTR_ERR(trans
);
289 btrfs_abort_transaction(trans
, ret
);
290 btrfs_end_transaction(trans
);
299 * btrfs_clone() - clone a range from inode file to another
301 * @src: Inode to clone from
302 * @inode: Inode to clone to
303 * @off: Offset within source to start clone from
304 * @olen: Original length, passed by user, of range to clone
305 * @olen_aligned: Block-aligned value of olen
306 * @destoff: Offset within @inode to start clone
307 * @no_time_update: Whether to update mtime/ctime on the target inode
309 static int btrfs_clone(struct inode
*src
, struct inode
*inode
,
310 const u64 off
, const u64 olen
, const u64 olen_aligned
,
311 const u64 destoff
, int no_time_update
)
313 struct btrfs_fs_info
*fs_info
= btrfs_sb(inode
->i_sb
);
314 struct btrfs_path
*path
= NULL
;
315 struct extent_buffer
*leaf
;
316 struct btrfs_trans_handle
*trans
;
318 struct btrfs_key key
;
322 const u64 len
= olen_aligned
;
323 u64 last_dest_end
= destoff
;
326 buf
= kvmalloc(fs_info
->nodesize
, GFP_KERNEL
);
330 path
= btrfs_alloc_path();
336 path
->reada
= READA_FORWARD
;
338 key
.objectid
= btrfs_ino(BTRFS_I(src
));
339 key
.type
= BTRFS_EXTENT_DATA_KEY
;
343 u64 next_key_min_offset
= key
.offset
+ 1;
344 struct btrfs_file_extent_item
*extent
;
348 struct btrfs_key new_key
;
349 u64 disko
= 0, diskl
= 0;
350 u64 datao
= 0, datal
= 0;
354 /* Note the key will change type as we walk through the tree */
355 ret
= btrfs_search_slot(NULL
, BTRFS_I(src
)->root
, &key
, path
,
360 * First search, if no extent item that starts at offset off was
361 * found but the previous item is an extent item, it's possible
362 * it might overlap our target range, therefore process it.
364 if (key
.offset
== off
&& ret
> 0 && path
->slots
[0] > 0) {
365 btrfs_item_key_to_cpu(path
->nodes
[0], &key
,
367 if (key
.type
== BTRFS_EXTENT_DATA_KEY
)
371 nritems
= btrfs_header_nritems(path
->nodes
[0]);
373 if (path
->slots
[0] >= nritems
) {
374 ret
= btrfs_next_leaf(BTRFS_I(src
)->root
, path
);
379 nritems
= btrfs_header_nritems(path
->nodes
[0]);
381 leaf
= path
->nodes
[0];
382 slot
= path
->slots
[0];
384 btrfs_item_key_to_cpu(leaf
, &key
, slot
);
385 if (key
.type
> BTRFS_EXTENT_DATA_KEY
||
386 key
.objectid
!= btrfs_ino(BTRFS_I(src
)))
389 ASSERT(key
.type
== BTRFS_EXTENT_DATA_KEY
);
391 extent
= btrfs_item_ptr(leaf
, slot
,
392 struct btrfs_file_extent_item
);
393 extent_gen
= btrfs_file_extent_generation(leaf
, extent
);
394 comp
= btrfs_file_extent_compression(leaf
, extent
);
395 type
= btrfs_file_extent_type(leaf
, extent
);
396 if (type
== BTRFS_FILE_EXTENT_REG
||
397 type
== BTRFS_FILE_EXTENT_PREALLOC
) {
398 disko
= btrfs_file_extent_disk_bytenr(leaf
, extent
);
399 diskl
= btrfs_file_extent_disk_num_bytes(leaf
, extent
);
400 datao
= btrfs_file_extent_offset(leaf
, extent
);
401 datal
= btrfs_file_extent_num_bytes(leaf
, extent
);
402 } else if (type
== BTRFS_FILE_EXTENT_INLINE
) {
403 /* Take upper bound, may be compressed */
404 datal
= btrfs_file_extent_ram_bytes(leaf
, extent
);
408 * The first search might have left us at an extent item that
409 * ends before our target range's start, can happen if we have
410 * holes and NO_HOLES feature enabled.
412 if (key
.offset
+ datal
<= off
) {
415 } else if (key
.offset
>= off
+ len
) {
418 next_key_min_offset
= key
.offset
+ datal
;
419 size
= btrfs_item_size_nr(leaf
, slot
);
420 read_extent_buffer(leaf
, buf
, btrfs_item_ptr_offset(leaf
, slot
),
423 btrfs_release_path(path
);
425 memcpy(&new_key
, &key
, sizeof(new_key
));
426 new_key
.objectid
= btrfs_ino(BTRFS_I(inode
));
427 if (off
<= key
.offset
)
428 new_key
.offset
= key
.offset
+ destoff
- off
;
430 new_key
.offset
= destoff
;
433 * Deal with a hole that doesn't have an extent item that
434 * represents it (NO_HOLES feature enabled).
435 * This hole is either in the middle of the cloning range or at
436 * the beginning (fully overlaps it or partially overlaps it).
438 if (new_key
.offset
!= last_dest_end
)
439 drop_start
= last_dest_end
;
441 drop_start
= new_key
.offset
;
443 if (type
== BTRFS_FILE_EXTENT_REG
||
444 type
== BTRFS_FILE_EXTENT_PREALLOC
) {
445 struct btrfs_replace_extent_info clone_info
;
448 * a | --- range to clone ---| b
449 * | ------------- extent ------------- |
452 /* Subtract range b */
453 if (key
.offset
+ datal
> off
+ len
)
454 datal
= off
+ len
- key
.offset
;
456 /* Subtract range a */
457 if (off
> key
.offset
) {
458 datao
+= off
- key
.offset
;
459 datal
-= off
- key
.offset
;
462 clone_info
.disk_offset
= disko
;
463 clone_info
.disk_len
= diskl
;
464 clone_info
.data_offset
= datao
;
465 clone_info
.data_len
= datal
;
466 clone_info
.file_offset
= new_key
.offset
;
467 clone_info
.extent_buf
= buf
;
468 clone_info
.is_new_extent
= false;
469 ret
= btrfs_replace_file_extents(inode
, path
, drop_start
,
470 new_key
.offset
+ datal
- 1, &clone_info
,
474 } else if (type
== BTRFS_FILE_EXTENT_INLINE
) {
476 * Inline extents always have to start at file offset 0
477 * and can never be bigger then the sector size. We can
478 * never clone only parts of an inline extent, since all
479 * reflink operations must start at a sector size aligned
480 * offset, and the length must be aligned too or end at
481 * the i_size (which implies the whole inlined data).
483 ASSERT(key
.offset
== 0);
484 ASSERT(datal
<= fs_info
->sectorsize
);
485 if (key
.offset
!= 0 || datal
> fs_info
->sectorsize
)
488 ret
= clone_copy_inline_extent(inode
, path
, &new_key
,
489 drop_start
, datal
, size
,
495 btrfs_release_path(path
);
498 * If this is a new extent update the last_reflink_trans of both
499 * inodes. This is used by fsync to make sure it does not log
500 * multiple checksum items with overlapping ranges. For older
501 * extents we don't need to do it since inode logging skips the
502 * checksums for older extents. Also ignore holes and inline
503 * extents because they don't have checksums in the csum tree.
505 if (extent_gen
== trans
->transid
&& disko
> 0) {
506 BTRFS_I(src
)->last_reflink_trans
= trans
->transid
;
507 BTRFS_I(inode
)->last_reflink_trans
= trans
->transid
;
510 last_dest_end
= ALIGN(new_key
.offset
+ datal
,
511 fs_info
->sectorsize
);
512 ret
= clone_finish_inode_update(trans
, inode
, last_dest_end
,
513 destoff
, olen
, no_time_update
);
516 if (new_key
.offset
+ datal
>= destoff
+ len
)
519 btrfs_release_path(path
);
520 key
.offset
= next_key_min_offset
;
522 if (fatal_signal_pending(current
)) {
531 if (last_dest_end
< destoff
+ len
) {
533 * We have an implicit hole that fully or partially overlaps our
534 * cloning range at its end. This means that we either have the
535 * NO_HOLES feature enabled or the implicit hole happened due to
536 * mixing buffered and direct IO writes against this file.
538 btrfs_release_path(path
);
540 ret
= btrfs_replace_file_extents(inode
, path
, last_dest_end
,
541 destoff
+ len
- 1, NULL
, &trans
);
545 ret
= clone_finish_inode_update(trans
, inode
, destoff
+ len
,
546 destoff
, olen
, no_time_update
);
550 btrfs_free_path(path
);
555 static void btrfs_double_extent_unlock(struct inode
*inode1
, u64 loff1
,
556 struct inode
*inode2
, u64 loff2
, u64 len
)
558 unlock_extent(&BTRFS_I(inode1
)->io_tree
, loff1
, loff1
+ len
- 1);
559 unlock_extent(&BTRFS_I(inode2
)->io_tree
, loff2
, loff2
+ len
- 1);
562 static void btrfs_double_extent_lock(struct inode
*inode1
, u64 loff1
,
563 struct inode
*inode2
, u64 loff2
, u64 len
)
565 if (inode1
< inode2
) {
566 swap(inode1
, inode2
);
568 } else if (inode1
== inode2
&& loff2
< loff1
) {
571 lock_extent(&BTRFS_I(inode1
)->io_tree
, loff1
, loff1
+ len
- 1);
572 lock_extent(&BTRFS_I(inode2
)->io_tree
, loff2
, loff2
+ len
- 1);
575 static int btrfs_extent_same_range(struct inode
*src
, u64 loff
, u64 len
,
576 struct inode
*dst
, u64 dst_loff
)
578 const u64 bs
= BTRFS_I(src
)->root
->fs_info
->sb
->s_blocksize
;
582 * Lock destination range to serialize with concurrent readpages() and
583 * source range to serialize with relocation.
585 btrfs_double_extent_lock(src
, loff
, dst
, dst_loff
, len
);
586 ret
= btrfs_clone(src
, dst
, loff
, len
, ALIGN(len
, bs
), dst_loff
, 1);
587 btrfs_double_extent_unlock(src
, loff
, dst
, dst_loff
, len
);
592 static int btrfs_extent_same(struct inode
*src
, u64 loff
, u64 olen
,
593 struct inode
*dst
, u64 dst_loff
)
596 u64 i
, tail_len
, chunk_count
;
597 struct btrfs_root
*root_dst
= BTRFS_I(dst
)->root
;
599 spin_lock(&root_dst
->root_item_lock
);
600 if (root_dst
->send_in_progress
) {
601 btrfs_warn_rl(root_dst
->fs_info
,
602 "cannot deduplicate to root %llu while send operations are using it (%d in progress)",
603 root_dst
->root_key
.objectid
,
604 root_dst
->send_in_progress
);
605 spin_unlock(&root_dst
->root_item_lock
);
608 root_dst
->dedupe_in_progress
++;
609 spin_unlock(&root_dst
->root_item_lock
);
611 tail_len
= olen
% BTRFS_MAX_DEDUPE_LEN
;
612 chunk_count
= div_u64(olen
, BTRFS_MAX_DEDUPE_LEN
);
614 for (i
= 0; i
< chunk_count
; i
++) {
615 ret
= btrfs_extent_same_range(src
, loff
, BTRFS_MAX_DEDUPE_LEN
,
620 loff
+= BTRFS_MAX_DEDUPE_LEN
;
621 dst_loff
+= BTRFS_MAX_DEDUPE_LEN
;
625 ret
= btrfs_extent_same_range(src
, loff
, tail_len
, dst
, dst_loff
);
627 spin_lock(&root_dst
->root_item_lock
);
628 root_dst
->dedupe_in_progress
--;
629 spin_unlock(&root_dst
->root_item_lock
);
634 static noinline
int btrfs_clone_files(struct file
*file
, struct file
*file_src
,
635 u64 off
, u64 olen
, u64 destoff
)
637 struct inode
*inode
= file_inode(file
);
638 struct inode
*src
= file_inode(file_src
);
639 struct btrfs_fs_info
*fs_info
= btrfs_sb(inode
->i_sb
);
643 u64 bs
= fs_info
->sb
->s_blocksize
;
646 * VFS's generic_remap_file_range_prep() protects us from cloning the
647 * eof block into the middle of a file, which would result in corruption
648 * if the file size is not blocksize aligned. So we don't need to check
649 * for that case here.
651 if (off
+ len
== src
->i_size
)
652 len
= ALIGN(src
->i_size
, bs
) - off
;
654 if (destoff
> inode
->i_size
) {
655 const u64 wb_start
= ALIGN_DOWN(inode
->i_size
, bs
);
657 ret
= btrfs_cont_expand(BTRFS_I(inode
), inode
->i_size
, destoff
);
661 * We may have truncated the last block if the inode's size is
662 * not sector size aligned, so we need to wait for writeback to
663 * complete before proceeding further, otherwise we can race
664 * with cloning and attempt to increment a reference to an
665 * extent that no longer exists (writeback completed right after
666 * we found the previous extent covering eof and before we
667 * attempted to increment its reference count).
669 ret
= btrfs_wait_ordered_range(inode
, wb_start
,
676 * Lock destination range to serialize with concurrent readpages() and
677 * source range to serialize with relocation.
679 btrfs_double_extent_lock(src
, off
, inode
, destoff
, len
);
680 ret
= btrfs_clone(src
, inode
, off
, olen
, len
, destoff
, 0);
681 btrfs_double_extent_unlock(src
, off
, inode
, destoff
, len
);
684 * We may have copied an inline extent into a page of the destination
685 * range, so wait for writeback to complete before truncating pages
686 * from the page cache. This is a rare case.
688 wb_ret
= btrfs_wait_ordered_range(inode
, destoff
, len
);
689 ret
= ret
? ret
: wb_ret
;
691 * Truncate page cache pages so that future reads will see the cloned
692 * data immediately and not the previous data.
694 truncate_inode_pages_range(&inode
->i_data
,
695 round_down(destoff
, PAGE_SIZE
),
696 round_up(destoff
+ len
, PAGE_SIZE
) - 1);
701 static int btrfs_remap_file_range_prep(struct file
*file_in
, loff_t pos_in
,
702 struct file
*file_out
, loff_t pos_out
,
703 loff_t
*len
, unsigned int remap_flags
)
705 struct inode
*inode_in
= file_inode(file_in
);
706 struct inode
*inode_out
= file_inode(file_out
);
707 u64 bs
= BTRFS_I(inode_out
)->root
->fs_info
->sb
->s_blocksize
;
708 bool same_inode
= inode_out
== inode_in
;
712 if (!(remap_flags
& REMAP_FILE_DEDUP
)) {
713 struct btrfs_root
*root_out
= BTRFS_I(inode_out
)->root
;
715 if (btrfs_root_readonly(root_out
))
718 if (file_in
->f_path
.mnt
!= file_out
->f_path
.mnt
||
719 inode_in
->i_sb
!= inode_out
->i_sb
)
723 /* Don't make the dst file partly checksummed */
724 if ((BTRFS_I(inode_in
)->flags
& BTRFS_INODE_NODATASUM
) !=
725 (BTRFS_I(inode_out
)->flags
& BTRFS_INODE_NODATASUM
)) {
730 * Now that the inodes are locked, we need to start writeback ourselves
731 * and can not rely on the writeback from the VFS's generic helper
732 * generic_remap_file_range_prep() because:
734 * 1) For compression we must call filemap_fdatawrite_range() range
735 * twice (btrfs_fdatawrite_range() does it for us), and the generic
736 * helper only calls it once;
738 * 2) filemap_fdatawrite_range(), called by the generic helper only
739 * waits for the writeback to complete, i.e. for IO to be done, and
740 * not for the ordered extents to complete. We need to wait for them
741 * to complete so that new file extent items are in the fs tree.
743 if (*len
== 0 && !(remap_flags
& REMAP_FILE_DEDUP
))
744 wb_len
= ALIGN(inode_in
->i_size
, bs
) - ALIGN_DOWN(pos_in
, bs
);
746 wb_len
= ALIGN(*len
, bs
);
749 * Since we don't lock ranges, wait for ongoing lockless dio writes (as
750 * any in progress could create its ordered extents after we wait for
751 * existing ordered extents below).
753 inode_dio_wait(inode_in
);
755 inode_dio_wait(inode_out
);
758 * Workaround to make sure NOCOW buffered write reach disk as NOCOW.
760 * Btrfs' back references do not have a block level granularity, they
761 * work at the whole extent level.
762 * NOCOW buffered write without data space reserved may not be able
763 * to fall back to CoW due to lack of data space, thus could cause
766 * Here we take a shortcut by flushing the whole inode, so that all
767 * nocow write should reach disk as nocow before we increase the
768 * reference of the extent. We could do better by only flushing NOCOW
769 * data, but that needs extra accounting.
771 * Also we don't need to check ASYNC_EXTENT, as async extent will be
772 * CoWed anyway, not affecting nocow part.
774 ret
= filemap_flush(inode_in
->i_mapping
);
778 ret
= btrfs_wait_ordered_range(inode_in
, ALIGN_DOWN(pos_in
, bs
),
782 ret
= btrfs_wait_ordered_range(inode_out
, ALIGN_DOWN(pos_out
, bs
),
787 return generic_remap_file_range_prep(file_in
, pos_in
, file_out
, pos_out
,
791 loff_t
btrfs_remap_file_range(struct file
*src_file
, loff_t off
,
792 struct file
*dst_file
, loff_t destoff
, loff_t len
,
793 unsigned int remap_flags
)
795 struct inode
*src_inode
= file_inode(src_file
);
796 struct inode
*dst_inode
= file_inode(dst_file
);
797 bool same_inode
= dst_inode
== src_inode
;
800 if (remap_flags
& ~(REMAP_FILE_DEDUP
| REMAP_FILE_ADVISORY
))
804 inode_lock(src_inode
);
806 lock_two_nondirectories(src_inode
, dst_inode
);
808 ret
= btrfs_remap_file_range_prep(src_file
, off
, dst_file
, destoff
,
810 if (ret
< 0 || len
== 0)
813 if (remap_flags
& REMAP_FILE_DEDUP
)
814 ret
= btrfs_extent_same(src_inode
, off
, len
, dst_inode
, destoff
);
816 ret
= btrfs_clone_files(dst_file
, src_file
, off
, len
, destoff
);
820 inode_unlock(src_inode
);
822 unlock_two_nondirectories(src_inode
, dst_inode
);
824 return ret
< 0 ? ret
: len
;