2 * Copyright (C) 2016 Oracle. All Rights Reserved.
4 * Author: Darrick J. Wong <darrick.wong@oracle.com>
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version 2
9 * of the License, or (at your option) any later version.
11 * This program is distributed in the hope that it would be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
22 #include "xfs_shared.h"
23 #include "xfs_format.h"
24 #include "xfs_log_format.h"
25 #include "xfs_trans_resv.h"
26 #include "xfs_mount.h"
27 #include "xfs_defer.h"
28 #include "xfs_da_format.h"
29 #include "xfs_da_btree.h"
30 #include "xfs_inode.h"
31 #include "xfs_trans.h"
32 #include "xfs_inode_item.h"
34 #include "xfs_bmap_util.h"
35 #include "xfs_error.h"
37 #include "xfs_dir2_priv.h"
38 #include "xfs_ioctl.h"
39 #include "xfs_trace.h"
41 #include "xfs_icache.h"
43 #include "xfs_btree.h"
44 #include "xfs_refcount_btree.h"
45 #include "xfs_refcount.h"
46 #include "xfs_bmap_btree.h"
47 #include "xfs_trans_space.h"
49 #include "xfs_alloc.h"
50 #include "xfs_quota_defs.h"
51 #include "xfs_quota.h"
52 #include "xfs_btree.h"
53 #include "xfs_bmap_btree.h"
54 #include "xfs_reflink.h"
55 #include "xfs_iomap.h"
56 #include "xfs_rmap_btree.h"
58 #include "xfs_ag_resv.h"
61 * Copy on Write of Shared Blocks
63 * XFS must preserve "the usual" file semantics even when two files share
64 * the same physical blocks. This means that a write to one file must not
65 * alter the blocks in a different file; the way that we'll do that is
66 * through the use of a copy-on-write mechanism. At a high level, that
67 * means that when we want to write to a shared block, we allocate a new
68 * block, write the data to the new block, and if that succeeds we map the
69 * new block into the file.
71 * XFS provides a "delayed allocation" mechanism that defers the allocation
72 * of disk blocks to dirty-but-not-yet-mapped file blocks as long as
73 * possible. This reduces fragmentation by enabling the filesystem to ask
74 * for bigger chunks less often, which is exactly what we want for CoW.
76 * The delalloc mechanism begins when the kernel wants to make a block
77 * writable (write_begin or page_mkwrite). If the offset is not mapped, we
78 * create a delalloc mapping, which is a regular in-core extent, but without
79 * a real startblock. (For delalloc mappings, the startblock encodes both
80 * a flag that this is a delalloc mapping, and a worst-case estimate of how
81 * many blocks might be required to put the mapping into the BMBT.) delalloc
82 * mappings are a reservation against the free space in the filesystem;
83 * adjacent mappings can also be combined into fewer larger mappings.
85 * As an optimization, the CoW extent size hint (cowextsz) creates
86 * outsized aligned delalloc reservations in the hope of landing out of
87 * order nearby CoW writes in a single extent on disk, thereby reducing
88 * fragmentation and improving future performance.
90 * D: --RRRRRRSSSRRRRRRRR--- (data fork)
91 * C: ------DDDDDDD--------- (CoW fork)
93 * When dirty pages are being written out (typically in writepage), the
94 * delalloc reservations are converted into unwritten mappings by
95 * allocating blocks and replacing the delalloc mapping with real ones.
96 * A delalloc mapping can be replaced by several unwritten ones if the
97 * free space is fragmented.
99 * D: --RRRRRRSSSRRRRRRRR---
100 * C: ------UUUUUUU---------
102 * We want to adapt the delalloc mechanism for copy-on-write, since the
103 * write paths are similar. The first two steps (creating the reservation
104 * and allocating the blocks) are exactly the same as delalloc except that
105 * the mappings must be stored in a separate CoW fork because we do not want
106 * to disturb the mapping in the data fork until we're sure that the write
107 * succeeded. IO completion in this case is the process of removing the old
108 * mapping from the data fork and moving the new mapping from the CoW fork to
109 * the data fork. This will be discussed shortly.
111 * For now, unaligned directio writes will be bounced back to the page cache.
112 * Block-aligned directio writes will use the same mechanism as buffered
115 * Just prior to submitting the actual disk write requests, we convert
116 * the extents representing the range of the file actually being written
117 * (as opposed to extra pieces created for the cowextsize hint) to real
118 * extents. This will become important in the next step:
120 * D: --RRRRRRSSSRRRRRRRR---
121 * C: ------UUrrUUU---------
123 * CoW remapping must be done after the data block write completes,
124 * because we don't want to destroy the old data fork map until we're sure
125 * the new block has been written. Since the new mappings are kept in a
126 * separate fork, we can simply iterate these mappings to find the ones
127 * that cover the file blocks that we just CoW'd. For each extent, simply
128 * unmap the corresponding range in the data fork, map the new range into
129 * the data fork, and remove the extent from the CoW fork. Because of
130 * the presence of the cowextsize hint, however, we must be careful
131 * only to remap the blocks that we've actually written out -- we must
132 * never remap delalloc reservations nor CoW staging blocks that have
133 * yet to be written. This corresponds exactly to the real extents in
136 * D: --RRRRRRrrSRRRRRRRR---
137 * C: ------UU--UUU---------
139 * Since the remapping operation can be applied to an arbitrary file
140 * range, we record the need for the remap step as a flag in the ioend
141 * instead of declaring a new IO type. This is required for direct io
142 * because we only have ioend for the whole dio, and we have to be able to
143 * remember the presence of unwritten blocks and CoW blocks with a single
144 * ioend structure. Better yet, the more ground we can cover with one
149 * Given an AG extent, find the lowest-numbered run of shared blocks
150 * within that range and return the range in fbno/flen. If
151 * find_end_of_shared is true, return the longest contiguous extent of
152 * shared blocks. If there are no shared extents, fbno and flen will
153 * be set to NULLAGBLOCK and 0, respectively.
156 xfs_reflink_find_shared(
157 struct xfs_mount
*mp
,
163 bool find_end_of_shared
)
165 struct xfs_buf
*agbp
;
166 struct xfs_btree_cur
*cur
;
169 error
= xfs_alloc_read_agf(mp
, NULL
, agno
, 0, &agbp
);
173 cur
= xfs_refcountbt_init_cursor(mp
, NULL
, agbp
, agno
, NULL
);
175 error
= xfs_refcount_find_shared(cur
, agbno
, aglen
, fbno
, flen
,
178 xfs_btree_del_cursor(cur
, error
? XFS_BTREE_ERROR
: XFS_BTREE_NOERROR
);
185 * Trim the mapping to the next block where there's a change in the
186 * shared/unshared status. More specifically, this means that we
187 * find the lowest-numbered extent of shared blocks that coincides with
188 * the given block mapping. If the shared extent overlaps the start of
189 * the mapping, trim the mapping to the end of the shared extent. If
190 * the shared region intersects the mapping, trim the mapping to the
191 * start of the shared extent. If there are no shared regions that
192 * overlap, just return the original extent.
195 xfs_reflink_trim_around_shared(
196 struct xfs_inode
*ip
,
197 struct xfs_bmbt_irec
*irec
,
208 /* Holes, unwritten, and delalloc extents cannot be shared */
209 if (!xfs_is_reflink_inode(ip
) ||
211 irec
->br_startblock
== HOLESTARTBLOCK
||
212 irec
->br_startblock
== DELAYSTARTBLOCK
||
213 isnullstartblock(irec
->br_startblock
)) {
218 trace_xfs_reflink_trim_around_shared(ip
, irec
);
220 agno
= XFS_FSB_TO_AGNO(ip
->i_mount
, irec
->br_startblock
);
221 agbno
= XFS_FSB_TO_AGBNO(ip
->i_mount
, irec
->br_startblock
);
222 aglen
= irec
->br_blockcount
;
224 error
= xfs_reflink_find_shared(ip
->i_mount
, agno
, agbno
,
225 aglen
, &fbno
, &flen
, true);
229 *shared
= *trimmed
= false;
230 if (fbno
== NULLAGBLOCK
) {
231 /* No shared blocks at all. */
233 } else if (fbno
== agbno
) {
235 * The start of this extent is shared. Truncate the
236 * mapping at the end of the shared region so that a
237 * subsequent iteration starts at the start of the
240 irec
->br_blockcount
= flen
;
247 * There's a shared extent midway through this extent.
248 * Truncate the mapping at the start of the shared
249 * extent so that a subsequent iteration starts at the
250 * start of the shared region.
252 irec
->br_blockcount
= fbno
- agbno
;
259 * Trim the passed in imap to the next shared/unshared extent boundary, and
260 * if imap->br_startoff points to a shared extent reserve space for it in the
261 * COW fork. In this case *shared is set to true, else to false.
263 * Note that imap will always contain the block numbers for the existing blocks
264 * in the data fork, as the upper layers need them for read-modify-write
268 xfs_reflink_reserve_cow(
269 struct xfs_inode
*ip
,
270 struct xfs_bmbt_irec
*imap
,
273 struct xfs_ifork
*ifp
= XFS_IFORK_PTR(ip
, XFS_COW_FORK
);
274 struct xfs_bmbt_irec got
;
276 bool eof
= false, trimmed
;
280 * Search the COW fork extent list first. This serves two purposes:
281 * first this implement the speculative preallocation using cowextisze,
282 * so that we also unshared block adjacent to shared blocks instead
283 * of just the shared blocks themselves. Second the lookup in the
284 * extent list is generally faster than going out to the shared extent
288 if (!xfs_iext_lookup_extent(ip
, ifp
, imap
->br_startoff
, &idx
, &got
))
290 if (!eof
&& got
.br_startoff
<= imap
->br_startoff
) {
291 trace_xfs_reflink_cow_found(ip
, imap
);
292 xfs_trim_extent(imap
, got
.br_startoff
, got
.br_blockcount
);
298 /* Trim the mapping to the nearest shared extent boundary. */
299 error
= xfs_reflink_trim_around_shared(ip
, imap
, shared
, &trimmed
);
303 /* Not shared? Just report the (potentially capped) extent. */
308 * Fork all the shared blocks from our write offset until the end of
311 error
= xfs_qm_dqattach_locked(ip
, 0);
315 error
= xfs_bmapi_reserve_delalloc(ip
, XFS_COW_FORK
, imap
->br_startoff
,
316 imap
->br_blockcount
, 0, &got
, &idx
, eof
);
317 if (error
== -ENOSPC
|| error
== -EDQUOT
)
318 trace_xfs_reflink_cow_enospc(ip
, imap
);
322 trace_xfs_reflink_cow_alloc(ip
, &got
);
326 /* Convert part of an unwritten CoW extent to a real one. */
328 xfs_reflink_convert_cow_extent(
329 struct xfs_inode
*ip
,
330 struct xfs_bmbt_irec
*imap
,
331 xfs_fileoff_t offset_fsb
,
332 xfs_filblks_t count_fsb
,
333 struct xfs_defer_ops
*dfops
)
335 struct xfs_bmbt_irec irec
= *imap
;
336 xfs_fsblock_t first_block
;
339 if (imap
->br_state
== XFS_EXT_NORM
)
342 xfs_trim_extent(&irec
, offset_fsb
, count_fsb
);
343 trace_xfs_reflink_convert_cow(ip
, &irec
);
344 if (irec
.br_blockcount
== 0)
346 return xfs_bmapi_write(NULL
, ip
, irec
.br_startoff
, irec
.br_blockcount
,
347 XFS_BMAPI_COWFORK
| XFS_BMAPI_CONVERT
, &first_block
,
348 0, &irec
, &nimaps
, dfops
);
351 /* Convert all of the unwritten CoW extents in a file's range to real ones. */
353 xfs_reflink_convert_cow(
354 struct xfs_inode
*ip
,
358 struct xfs_bmbt_irec got
;
359 struct xfs_defer_ops dfops
;
360 struct xfs_mount
*mp
= ip
->i_mount
;
361 struct xfs_ifork
*ifp
= XFS_IFORK_PTR(ip
, XFS_COW_FORK
);
362 xfs_fileoff_t offset_fsb
= XFS_B_TO_FSBT(mp
, offset
);
363 xfs_fileoff_t end_fsb
= XFS_B_TO_FSB(mp
, offset
+ count
);
368 xfs_ilock(ip
, XFS_ILOCK_EXCL
);
370 /* Convert all the extents to real from unwritten. */
371 for (found
= xfs_iext_lookup_extent(ip
, ifp
, offset_fsb
, &idx
, &got
);
372 found
&& got
.br_startoff
< end_fsb
;
373 found
= xfs_iext_get_extent(ifp
, ++idx
, &got
)) {
374 error
= xfs_reflink_convert_cow_extent(ip
, &got
, offset_fsb
,
375 end_fsb
- offset_fsb
, &dfops
);
381 xfs_iunlock(ip
, XFS_ILOCK_EXCL
);
385 /* Allocate all CoW reservations covering a range of blocks in a file. */
387 __xfs_reflink_allocate_cow(
388 struct xfs_inode
*ip
,
389 xfs_fileoff_t
*offset_fsb
,
390 xfs_fileoff_t end_fsb
)
392 struct xfs_mount
*mp
= ip
->i_mount
;
393 struct xfs_bmbt_irec imap
;
394 struct xfs_defer_ops dfops
;
395 struct xfs_trans
*tp
;
396 xfs_fsblock_t first_block
;
397 int nimaps
= 1, error
;
400 xfs_defer_init(&dfops
, &first_block
);
402 error
= xfs_trans_alloc(mp
, &M_RES(mp
)->tr_write
, 0, 0,
403 XFS_TRANS_RESERVE
, &tp
);
407 xfs_ilock(ip
, XFS_ILOCK_EXCL
);
409 /* Read extent from the source file. */
411 error
= xfs_bmapi_read(ip
, *offset_fsb
, end_fsb
- *offset_fsb
,
417 /* Make sure there's a CoW reservation for it. */
418 error
= xfs_reflink_reserve_cow(ip
, &imap
, &shared
);
420 goto out_trans_cancel
;
423 *offset_fsb
= imap
.br_startoff
+ imap
.br_blockcount
;
424 goto out_trans_cancel
;
427 /* Allocate the entire reservation as unwritten blocks. */
428 xfs_trans_ijoin(tp
, ip
, 0);
429 error
= xfs_bmapi_write(tp
, ip
, imap
.br_startoff
, imap
.br_blockcount
,
430 XFS_BMAPI_COWFORK
| XFS_BMAPI_PREALLOC
, &first_block
,
431 XFS_EXTENTADD_SPACE_RES(mp
, XFS_DATA_FORK
),
432 &imap
, &nimaps
, &dfops
);
434 goto out_trans_cancel
;
437 error
= xfs_defer_finish(&tp
, &dfops
, NULL
);
439 goto out_trans_cancel
;
441 error
= xfs_trans_commit(tp
);
443 *offset_fsb
= imap
.br_startoff
+ imap
.br_blockcount
;
445 xfs_iunlock(ip
, XFS_ILOCK_EXCL
);
448 xfs_defer_cancel(&dfops
);
449 xfs_trans_cancel(tp
);
453 /* Allocate all CoW reservations covering a part of a file. */
455 xfs_reflink_allocate_cow_range(
456 struct xfs_inode
*ip
,
460 struct xfs_mount
*mp
= ip
->i_mount
;
461 xfs_fileoff_t offset_fsb
= XFS_B_TO_FSBT(mp
, offset
);
462 xfs_fileoff_t end_fsb
= XFS_B_TO_FSB(mp
, offset
+ count
);
465 ASSERT(xfs_is_reflink_inode(ip
));
467 trace_xfs_reflink_allocate_cow_range(ip
, offset
, count
);
470 * Make sure that the dquots are there.
472 error
= xfs_qm_dqattach(ip
, 0);
476 while (offset_fsb
< end_fsb
) {
477 error
= __xfs_reflink_allocate_cow(ip
, &offset_fsb
, end_fsb
);
479 trace_xfs_reflink_allocate_cow_range_error(ip
, error
,
485 /* Convert the CoW extents to regular. */
486 return xfs_reflink_convert_cow(ip
, offset
, count
);
490 * Find the CoW reservation for a given byte offset of a file.
493 xfs_reflink_find_cow_mapping(
494 struct xfs_inode
*ip
,
496 struct xfs_bmbt_irec
*imap
)
498 struct xfs_ifork
*ifp
= XFS_IFORK_PTR(ip
, XFS_COW_FORK
);
499 xfs_fileoff_t offset_fsb
;
500 struct xfs_bmbt_irec got
;
503 ASSERT(xfs_isilocked(ip
, XFS_ILOCK_EXCL
| XFS_ILOCK_SHARED
));
504 ASSERT(xfs_is_reflink_inode(ip
));
506 offset_fsb
= XFS_B_TO_FSBT(ip
->i_mount
, offset
);
507 if (!xfs_iext_lookup_extent(ip
, ifp
, offset_fsb
, &idx
, &got
))
509 if (got
.br_startoff
> offset_fsb
)
512 trace_xfs_reflink_find_cow_mapping(ip
, offset
, 1, XFS_IO_OVERWRITE
,
519 * Trim an extent to end at the next CoW reservation past offset_fsb.
522 xfs_reflink_trim_irec_to_next_cow(
523 struct xfs_inode
*ip
,
524 xfs_fileoff_t offset_fsb
,
525 struct xfs_bmbt_irec
*imap
)
527 struct xfs_ifork
*ifp
= XFS_IFORK_PTR(ip
, XFS_COW_FORK
);
528 struct xfs_bmbt_irec got
;
531 if (!xfs_is_reflink_inode(ip
))
534 /* Find the extent in the CoW fork. */
535 if (!xfs_iext_lookup_extent(ip
, ifp
, offset_fsb
, &idx
, &got
))
538 /* This is the extent before; try sliding up one. */
539 if (got
.br_startoff
< offset_fsb
) {
540 if (!xfs_iext_get_extent(ifp
, idx
+ 1, &got
))
544 if (got
.br_startoff
>= imap
->br_startoff
+ imap
->br_blockcount
)
547 imap
->br_blockcount
= got
.br_startoff
- imap
->br_startoff
;
548 trace_xfs_reflink_trim_irec(ip
, imap
);
552 * Cancel CoW reservations for some block range of an inode.
554 * If cancel_real is true this function cancels all COW fork extents for the
555 * inode; if cancel_real is false, real extents are not cleared.
558 xfs_reflink_cancel_cow_blocks(
559 struct xfs_inode
*ip
,
560 struct xfs_trans
**tpp
,
561 xfs_fileoff_t offset_fsb
,
562 xfs_fileoff_t end_fsb
,
565 struct xfs_ifork
*ifp
= XFS_IFORK_PTR(ip
, XFS_COW_FORK
);
566 struct xfs_bmbt_irec got
, del
;
568 xfs_fsblock_t firstfsb
;
569 struct xfs_defer_ops dfops
;
572 if (!xfs_is_reflink_inode(ip
))
574 if (!xfs_iext_lookup_extent(ip
, ifp
, offset_fsb
, &idx
, &got
))
577 while (got
.br_startoff
< end_fsb
) {
579 xfs_trim_extent(&del
, offset_fsb
, end_fsb
- offset_fsb
);
580 trace_xfs_reflink_cancel_cow(ip
, &del
);
582 if (isnullstartblock(del
.br_startblock
)) {
583 error
= xfs_bmap_del_extent_delay(ip
, XFS_COW_FORK
,
587 } else if (del
.br_state
== XFS_EXT_UNWRITTEN
|| cancel_real
) {
588 xfs_trans_ijoin(*tpp
, ip
, 0);
589 xfs_defer_init(&dfops
, &firstfsb
);
591 /* Free the CoW orphan record. */
592 error
= xfs_refcount_free_cow_extent(ip
->i_mount
,
593 &dfops
, del
.br_startblock
,
598 xfs_bmap_add_free(ip
->i_mount
, &dfops
,
599 del
.br_startblock
, del
.br_blockcount
,
602 /* Update quota accounting */
603 xfs_trans_mod_dquot_byino(*tpp
, ip
, XFS_TRANS_DQ_BCOUNT
,
604 -(long)del
.br_blockcount
);
606 /* Roll the transaction */
607 error
= xfs_defer_finish(tpp
, &dfops
, ip
);
609 xfs_defer_cancel(&dfops
);
613 /* Remove the mapping from the CoW fork. */
614 xfs_bmap_del_extent_cow(ip
, &idx
, &got
, &del
);
617 if (!xfs_iext_get_extent(ifp
, ++idx
, &got
))
621 /* clear tag if cow fork is emptied */
623 xfs_inode_clear_cowblocks_tag(ip
);
629 * Cancel CoW reservations for some byte range of an inode.
631 * If cancel_real is true this function cancels all COW fork extents for the
632 * inode; if cancel_real is false, real extents are not cleared.
635 xfs_reflink_cancel_cow_range(
636 struct xfs_inode
*ip
,
641 struct xfs_trans
*tp
;
642 xfs_fileoff_t offset_fsb
;
643 xfs_fileoff_t end_fsb
;
646 trace_xfs_reflink_cancel_cow_range(ip
, offset
, count
);
647 ASSERT(xfs_is_reflink_inode(ip
));
649 offset_fsb
= XFS_B_TO_FSBT(ip
->i_mount
, offset
);
650 if (count
== NULLFILEOFF
)
651 end_fsb
= NULLFILEOFF
;
653 end_fsb
= XFS_B_TO_FSB(ip
->i_mount
, offset
+ count
);
655 /* Start a rolling transaction to remove the mappings */
656 error
= xfs_trans_alloc(ip
->i_mount
, &M_RES(ip
->i_mount
)->tr_write
,
661 xfs_ilock(ip
, XFS_ILOCK_EXCL
);
662 xfs_trans_ijoin(tp
, ip
, 0);
664 /* Scrape out the old CoW reservations */
665 error
= xfs_reflink_cancel_cow_blocks(ip
, &tp
, offset_fsb
, end_fsb
,
670 error
= xfs_trans_commit(tp
);
672 xfs_iunlock(ip
, XFS_ILOCK_EXCL
);
676 xfs_trans_cancel(tp
);
677 xfs_iunlock(ip
, XFS_ILOCK_EXCL
);
679 trace_xfs_reflink_cancel_cow_range_error(ip
, error
, _RET_IP_
);
684 * Remap parts of a file's data fork after a successful CoW.
688 struct xfs_inode
*ip
,
692 struct xfs_ifork
*ifp
= XFS_IFORK_PTR(ip
, XFS_COW_FORK
);
693 struct xfs_bmbt_irec got
, del
;
694 struct xfs_trans
*tp
;
695 xfs_fileoff_t offset_fsb
;
696 xfs_fileoff_t end_fsb
;
697 xfs_fsblock_t firstfsb
;
698 struct xfs_defer_ops dfops
;
700 unsigned int resblks
;
704 trace_xfs_reflink_end_cow(ip
, offset
, count
);
706 /* No COW extents? That's easy! */
707 if (ifp
->if_bytes
== 0)
710 offset_fsb
= XFS_B_TO_FSBT(ip
->i_mount
, offset
);
711 end_fsb
= XFS_B_TO_FSB(ip
->i_mount
, offset
+ count
);
713 /* Start a rolling transaction to switch the mappings */
714 resblks
= XFS_EXTENTADD_SPACE_RES(ip
->i_mount
, XFS_DATA_FORK
);
715 error
= xfs_trans_alloc(ip
->i_mount
, &M_RES(ip
->i_mount
)->tr_write
,
720 xfs_ilock(ip
, XFS_ILOCK_EXCL
);
721 xfs_trans_ijoin(tp
, ip
, 0);
723 /* If there is a hole at end_fsb - 1 go to the previous extent */
724 if (!xfs_iext_lookup_extent(ip
, ifp
, end_fsb
- 1, &idx
, &got
) ||
725 got
.br_startoff
> end_fsb
) {
727 xfs_iext_get_extent(ifp
, --idx
, &got
);
730 /* Walk backwards until we're out of the I/O range... */
731 while (got
.br_startoff
+ got
.br_blockcount
> offset_fsb
) {
733 xfs_trim_extent(&del
, offset_fsb
, end_fsb
- offset_fsb
);
735 /* Extent delete may have bumped idx forward */
736 if (!del
.br_blockcount
) {
741 ASSERT(!isnullstartblock(got
.br_startblock
));
744 * Don't remap unwritten extents; these are
745 * speculatively preallocated CoW extents that have been
746 * allocated but have not yet been involved in a write.
748 if (got
.br_state
== XFS_EXT_UNWRITTEN
) {
753 /* Unmap the old blocks in the data fork. */
754 xfs_defer_init(&dfops
, &firstfsb
);
755 rlen
= del
.br_blockcount
;
756 error
= __xfs_bunmapi(tp
, ip
, del
.br_startoff
, &rlen
, 0, 1,
761 /* Trim the extent to whatever got unmapped. */
763 xfs_trim_extent(&del
, del
.br_startoff
+ rlen
,
764 del
.br_blockcount
- rlen
);
766 trace_xfs_reflink_cow_remap(ip
, &del
);
768 /* Free the CoW orphan record. */
769 error
= xfs_refcount_free_cow_extent(tp
->t_mountp
, &dfops
,
770 del
.br_startblock
, del
.br_blockcount
);
774 /* Map the new blocks into the data fork. */
775 error
= xfs_bmap_map_extent(tp
->t_mountp
, &dfops
, ip
, &del
);
779 /* Remove the mapping from the CoW fork. */
780 xfs_bmap_del_extent_cow(ip
, &idx
, &got
, &del
);
782 error
= xfs_defer_finish(&tp
, &dfops
, ip
);
786 if (!xfs_iext_get_extent(ifp
, idx
, &got
))
790 error
= xfs_trans_commit(tp
);
791 xfs_iunlock(ip
, XFS_ILOCK_EXCL
);
797 xfs_defer_cancel(&dfops
);
798 xfs_trans_cancel(tp
);
799 xfs_iunlock(ip
, XFS_ILOCK_EXCL
);
801 trace_xfs_reflink_end_cow_error(ip
, error
, _RET_IP_
);
806 * Free leftover CoW reservations that didn't get cleaned out.
809 xfs_reflink_recover_cow(
810 struct xfs_mount
*mp
)
815 if (!xfs_sb_version_hasreflink(&mp
->m_sb
))
818 for (agno
= 0; agno
< mp
->m_sb
.sb_agcount
; agno
++) {
819 error
= xfs_refcount_recover_cow_leftovers(mp
, agno
);
828 * Reflinking (Block) Ranges of Two Files Together
830 * First, ensure that the reflink flag is set on both inodes. The flag is an
831 * optimization to avoid unnecessary refcount btree lookups in the write path.
833 * Now we can iteratively remap the range of extents (and holes) in src to the
834 * corresponding ranges in dest. Let drange and srange denote the ranges of
835 * logical blocks in dest and src touched by the reflink operation.
837 * While the length of drange is greater than zero,
838 * - Read src's bmbt at the start of srange ("imap")
839 * - If imap doesn't exist, make imap appear to start at the end of srange
841 * - If imap starts before srange, advance imap to start at srange.
842 * - If imap goes beyond srange, truncate imap to end at the end of srange.
843 * - Punch (imap start - srange start + imap len) blocks from dest at
844 * offset (drange start).
845 * - If imap points to a real range of pblks,
846 * > Increase the refcount of the imap's pblks
847 * > Map imap's pblks into dest at the offset
848 * (drange start + imap start - srange start)
849 * - Advance drange and srange by (imap start - srange start + imap len)
851 * Finally, if the reflink made dest longer, update both the in-core and
852 * on-disk file sizes.
854 * ASCII Art Demonstration:
856 * Let's say we want to reflink this source file:
858 * ----SSSSSSS-SSSSS----SSSSSS (src file)
859 * <-------------------->
861 * into this destination file:
863 * --DDDDDDDDDDDDDDDDDDD--DDD (dest file)
864 * <-------------------->
865 * '-' means a hole, and 'S' and 'D' are written blocks in the src and dest.
866 * Observe that the range has different logical offsets in either file.
868 * Consider that the first extent in the source file doesn't line up with our
869 * reflink range. Unmapping and remapping are separate operations, so we can
870 * unmap more blocks from the destination file than we remap.
872 * ----SSSSSSS-SSSSS----SSSSSS
874 * --DDDDD---------DDDDD--DDD
877 * Now remap the source extent into the destination file:
879 * ----SSSSSSS-SSSSS----SSSSSS
881 * --DDDDD--SSSSSSSDDDDD--DDD
884 * Do likewise with the second hole and extent in our range. Holes in the
885 * unmap range don't affect our operation.
887 * ----SSSSSSS-SSSSS----SSSSSS
889 * --DDDDD--SSSSSSS-SSSSS-DDD
892 * Finally, unmap and remap part of the third extent. This will increase the
893 * size of the destination file.
895 * ----SSSSSSS-SSSSS----SSSSSS
897 * --DDDDD--SSSSSSS-SSSSS----SSS
900 * Once we update the destination file's i_size, we're done.
904 * Ensure the reflink bit is set in both inodes.
907 xfs_reflink_set_inode_flag(
908 struct xfs_inode
*src
,
909 struct xfs_inode
*dest
)
911 struct xfs_mount
*mp
= src
->i_mount
;
913 struct xfs_trans
*tp
;
915 if (xfs_is_reflink_inode(src
) && xfs_is_reflink_inode(dest
))
918 error
= xfs_trans_alloc(mp
, &M_RES(mp
)->tr_ichange
, 0, 0, 0, &tp
);
922 /* Lock both files against IO */
923 if (src
->i_ino
== dest
->i_ino
)
924 xfs_ilock(src
, XFS_ILOCK_EXCL
);
926 xfs_lock_two_inodes(src
, dest
, XFS_ILOCK_EXCL
);
928 if (!xfs_is_reflink_inode(src
)) {
929 trace_xfs_reflink_set_inode_flag(src
);
930 xfs_trans_ijoin(tp
, src
, XFS_ILOCK_EXCL
);
931 src
->i_d
.di_flags2
|= XFS_DIFLAG2_REFLINK
;
932 xfs_trans_log_inode(tp
, src
, XFS_ILOG_CORE
);
933 xfs_ifork_init_cow(src
);
935 xfs_iunlock(src
, XFS_ILOCK_EXCL
);
937 if (src
->i_ino
== dest
->i_ino
)
940 if (!xfs_is_reflink_inode(dest
)) {
941 trace_xfs_reflink_set_inode_flag(dest
);
942 xfs_trans_ijoin(tp
, dest
, XFS_ILOCK_EXCL
);
943 dest
->i_d
.di_flags2
|= XFS_DIFLAG2_REFLINK
;
944 xfs_trans_log_inode(tp
, dest
, XFS_ILOG_CORE
);
945 xfs_ifork_init_cow(dest
);
947 xfs_iunlock(dest
, XFS_ILOCK_EXCL
);
950 error
= xfs_trans_commit(tp
);
956 trace_xfs_reflink_set_inode_flag_error(dest
, error
, _RET_IP_
);
961 * Update destination inode size & cowextsize hint, if necessary.
964 xfs_reflink_update_dest(
965 struct xfs_inode
*dest
,
967 xfs_extlen_t cowextsize
,
970 struct xfs_mount
*mp
= dest
->i_mount
;
971 struct xfs_trans
*tp
;
974 if (is_dedupe
&& newlen
<= i_size_read(VFS_I(dest
)) && cowextsize
== 0)
977 error
= xfs_trans_alloc(mp
, &M_RES(mp
)->tr_ichange
, 0, 0, 0, &tp
);
981 xfs_ilock(dest
, XFS_ILOCK_EXCL
);
982 xfs_trans_ijoin(tp
, dest
, XFS_ILOCK_EXCL
);
984 if (newlen
> i_size_read(VFS_I(dest
))) {
985 trace_xfs_reflink_update_inode_size(dest
, newlen
);
986 i_size_write(VFS_I(dest
), newlen
);
987 dest
->i_d
.di_size
= newlen
;
991 dest
->i_d
.di_cowextsize
= cowextsize
;
992 dest
->i_d
.di_flags2
|= XFS_DIFLAG2_COWEXTSIZE
;
996 xfs_trans_ichgtime(tp
, dest
,
997 XFS_ICHGTIME_MOD
| XFS_ICHGTIME_CHG
);
999 xfs_trans_log_inode(tp
, dest
, XFS_ILOG_CORE
);
1001 error
= xfs_trans_commit(tp
);
1007 trace_xfs_reflink_update_inode_size_error(dest
, error
, _RET_IP_
);
1012 * Do we have enough reserve in this AG to handle a reflink? The refcount
1013 * btree already reserved all the space it needs, but the rmap btree can grow
1014 * infinitely, so we won't allow more reflinks when the AG is down to the
1018 xfs_reflink_ag_has_free_space(
1019 struct xfs_mount
*mp
,
1020 xfs_agnumber_t agno
)
1022 struct xfs_perag
*pag
;
1025 if (!xfs_sb_version_hasrmapbt(&mp
->m_sb
))
1028 pag
= xfs_perag_get(mp
, agno
);
1029 if (xfs_ag_resv_critical(pag
, XFS_AG_RESV_AGFL
) ||
1030 xfs_ag_resv_critical(pag
, XFS_AG_RESV_METADATA
))
1037 * Unmap a range of blocks from a file, then map other blocks into the hole.
1038 * The range to unmap is (destoff : destoff + srcioff + irec->br_blockcount).
1039 * The extent irec is mapped into dest at irec->br_startoff.
1042 xfs_reflink_remap_extent(
1043 struct xfs_inode
*ip
,
1044 struct xfs_bmbt_irec
*irec
,
1045 xfs_fileoff_t destoff
,
1046 xfs_off_t new_isize
)
1048 struct xfs_mount
*mp
= ip
->i_mount
;
1049 struct xfs_trans
*tp
;
1050 xfs_fsblock_t firstfsb
;
1051 unsigned int resblks
;
1052 struct xfs_defer_ops dfops
;
1053 struct xfs_bmbt_irec uirec
;
1056 xfs_filblks_t unmap_len
;
1060 unmap_len
= irec
->br_startoff
+ irec
->br_blockcount
- destoff
;
1061 trace_xfs_reflink_punch_range(ip
, destoff
, unmap_len
);
1063 /* Only remap normal extents. */
1064 real_extent
= (irec
->br_startblock
!= HOLESTARTBLOCK
&&
1065 irec
->br_startblock
!= DELAYSTARTBLOCK
&&
1066 !ISUNWRITTEN(irec
));
1068 /* No reflinking if we're low on space */
1070 error
= xfs_reflink_ag_has_free_space(mp
,
1071 XFS_FSB_TO_AGNO(mp
, irec
->br_startblock
));
1076 /* Start a rolling transaction to switch the mappings */
1077 resblks
= XFS_EXTENTADD_SPACE_RES(ip
->i_mount
, XFS_DATA_FORK
);
1078 error
= xfs_trans_alloc(mp
, &M_RES(mp
)->tr_write
, resblks
, 0, 0, &tp
);
1082 xfs_ilock(ip
, XFS_ILOCK_EXCL
);
1083 xfs_trans_ijoin(tp
, ip
, 0);
1085 /* If we're not just clearing space, then do we have enough quota? */
1087 error
= xfs_trans_reserve_quota_nblks(tp
, ip
,
1088 irec
->br_blockcount
, 0, XFS_QMOPT_RES_REGBLKS
);
1093 trace_xfs_reflink_remap(ip
, irec
->br_startoff
,
1094 irec
->br_blockcount
, irec
->br_startblock
);
1096 /* Unmap the old blocks in the data fork. */
1099 xfs_defer_init(&dfops
, &firstfsb
);
1100 error
= __xfs_bunmapi(tp
, ip
, destoff
, &rlen
, 0, 1,
1106 * Trim the extent to whatever got unmapped.
1107 * Remember, bunmapi works backwards.
1109 uirec
.br_startblock
= irec
->br_startblock
+ rlen
;
1110 uirec
.br_startoff
= irec
->br_startoff
+ rlen
;
1111 uirec
.br_blockcount
= unmap_len
- rlen
;
1114 /* If this isn't a real mapping, we're done. */
1115 if (!real_extent
|| uirec
.br_blockcount
== 0)
1118 trace_xfs_reflink_remap(ip
, uirec
.br_startoff
,
1119 uirec
.br_blockcount
, uirec
.br_startblock
);
1121 /* Update the refcount tree */
1122 error
= xfs_refcount_increase_extent(mp
, &dfops
, &uirec
);
1126 /* Map the new blocks into the data fork. */
1127 error
= xfs_bmap_map_extent(mp
, &dfops
, ip
, &uirec
);
1131 /* Update quota accounting. */
1132 xfs_trans_mod_dquot_byino(tp
, ip
, XFS_TRANS_DQ_BCOUNT
,
1133 uirec
.br_blockcount
);
1135 /* Update dest isize if needed. */
1136 newlen
= XFS_FSB_TO_B(mp
,
1137 uirec
.br_startoff
+ uirec
.br_blockcount
);
1138 newlen
= min_t(xfs_off_t
, newlen
, new_isize
);
1139 if (newlen
> i_size_read(VFS_I(ip
))) {
1140 trace_xfs_reflink_update_inode_size(ip
, newlen
);
1141 i_size_write(VFS_I(ip
), newlen
);
1142 ip
->i_d
.di_size
= newlen
;
1143 xfs_trans_log_inode(tp
, ip
, XFS_ILOG_CORE
);
1147 /* Process all the deferred stuff. */
1148 error
= xfs_defer_finish(&tp
, &dfops
, ip
);
1153 error
= xfs_trans_commit(tp
);
1154 xfs_iunlock(ip
, XFS_ILOCK_EXCL
);
1160 xfs_defer_cancel(&dfops
);
1162 xfs_trans_cancel(tp
);
1163 xfs_iunlock(ip
, XFS_ILOCK_EXCL
);
1165 trace_xfs_reflink_remap_extent_error(ip
, error
, _RET_IP_
);
1170 * Iteratively remap one file's extents (and holes) to another's.
1173 xfs_reflink_remap_blocks(
1174 struct xfs_inode
*src
,
1175 xfs_fileoff_t srcoff
,
1176 struct xfs_inode
*dest
,
1177 xfs_fileoff_t destoff
,
1179 xfs_off_t new_isize
)
1181 struct xfs_bmbt_irec imap
;
1184 xfs_filblks_t range_len
;
1186 /* drange = (destoff, destoff + len); srange = (srcoff, srcoff + len) */
1188 trace_xfs_reflink_remap_blocks_loop(src
, srcoff
, len
,
1190 /* Read extent from the source file */
1192 xfs_ilock(src
, XFS_ILOCK_EXCL
);
1193 error
= xfs_bmapi_read(src
, srcoff
, len
, &imap
, &nimaps
, 0);
1194 xfs_iunlock(src
, XFS_ILOCK_EXCL
);
1197 ASSERT(nimaps
== 1);
1199 trace_xfs_reflink_remap_imap(src
, srcoff
, len
, XFS_IO_OVERWRITE
,
1202 /* Translate imap into the destination file. */
1203 range_len
= imap
.br_startoff
+ imap
.br_blockcount
- srcoff
;
1204 imap
.br_startoff
+= destoff
- srcoff
;
1206 /* Clear dest from destoff to the end of imap and map it in. */
1207 error
= xfs_reflink_remap_extent(dest
, &imap
, destoff
,
1212 if (fatal_signal_pending(current
)) {
1217 /* Advance drange/srange */
1218 srcoff
+= range_len
;
1219 destoff
+= range_len
;
1226 trace_xfs_reflink_remap_blocks_error(dest
, error
, _RET_IP_
);
1231 * Link a range of blocks from one file to another.
1234 xfs_reflink_remap_range(
1235 struct file
*file_in
,
1237 struct file
*file_out
,
1242 struct inode
*inode_in
= file_inode(file_in
);
1243 struct xfs_inode
*src
= XFS_I(inode_in
);
1244 struct inode
*inode_out
= file_inode(file_out
);
1245 struct xfs_inode
*dest
= XFS_I(inode_out
);
1246 struct xfs_mount
*mp
= src
->i_mount
;
1247 bool same_inode
= (inode_in
== inode_out
);
1248 xfs_fileoff_t sfsbno
, dfsbno
;
1249 xfs_filblks_t fsblen
;
1250 xfs_extlen_t cowextsize
;
1253 if (!xfs_sb_version_hasreflink(&mp
->m_sb
))
1256 if (XFS_FORCED_SHUTDOWN(mp
))
1259 /* Lock both files against IO */
1260 lock_two_nondirectories(inode_in
, inode_out
);
1262 xfs_ilock(src
, XFS_MMAPLOCK_EXCL
);
1264 xfs_lock_two_inodes(src
, dest
, XFS_MMAPLOCK_EXCL
);
1266 /* Check file eligibility and prepare for block sharing. */
1268 /* Don't reflink realtime inodes */
1269 if (XFS_IS_REALTIME_INODE(src
) || XFS_IS_REALTIME_INODE(dest
))
1272 /* Don't share DAX file data for now. */
1273 if (IS_DAX(inode_in
) || IS_DAX(inode_out
))
1276 ret
= vfs_clone_file_prep_inodes(inode_in
, pos_in
, inode_out
, pos_out
,
1281 trace_xfs_reflink_remap_range(src
, pos_in
, len
, dest
, pos_out
);
1283 /* Set flags and remap blocks. */
1284 ret
= xfs_reflink_set_inode_flag(src
, dest
);
1288 dfsbno
= XFS_B_TO_FSBT(mp
, pos_out
);
1289 sfsbno
= XFS_B_TO_FSBT(mp
, pos_in
);
1290 fsblen
= XFS_B_TO_FSB(mp
, len
);
1291 ret
= xfs_reflink_remap_blocks(src
, sfsbno
, dest
, dfsbno
, fsblen
,
1296 /* Zap any page cache for the destination file's range. */
1297 truncate_inode_pages_range(&inode_out
->i_data
, pos_out
,
1298 PAGE_ALIGN(pos_out
+ len
) - 1);
1301 * Carry the cowextsize hint from src to dest if we're sharing the
1302 * entire source file to the entire destination file, the source file
1303 * has a cowextsize hint, and the destination file does not.
1306 if (pos_in
== 0 && len
== i_size_read(inode_in
) &&
1307 (src
->i_d
.di_flags2
& XFS_DIFLAG2_COWEXTSIZE
) &&
1308 pos_out
== 0 && len
>= i_size_read(inode_out
) &&
1309 !(dest
->i_d
.di_flags2
& XFS_DIFLAG2_COWEXTSIZE
))
1310 cowextsize
= src
->i_d
.di_cowextsize
;
1312 ret
= xfs_reflink_update_dest(dest
, pos_out
+ len
, cowextsize
,
1316 xfs_iunlock(src
, XFS_MMAPLOCK_EXCL
);
1318 xfs_iunlock(dest
, XFS_MMAPLOCK_EXCL
);
1319 unlock_two_nondirectories(inode_in
, inode_out
);
1321 trace_xfs_reflink_remap_range_error(dest
, ret
, _RET_IP_
);
1326 * The user wants to preemptively CoW all shared blocks in this file,
1327 * which enables us to turn off the reflink flag. Iterate all
1328 * extents which are not prealloc/delalloc to see which ranges are
1329 * mentioned in the refcount tree, then read those blocks into the
1330 * pagecache, dirty them, fsync them back out, and then we can update
1331 * the inode flag. What happens if we run out of memory? :)
1334 xfs_reflink_dirty_extents(
1335 struct xfs_inode
*ip
,
1340 struct xfs_mount
*mp
= ip
->i_mount
;
1341 xfs_agnumber_t agno
;
1342 xfs_agblock_t agbno
;
1348 struct xfs_bmbt_irec map
[2];
1352 while (end
- fbno
> 0) {
1355 * Look for extents in the file. Skip holes, delalloc, or
1356 * unwritten extents; they can't be reflinked.
1358 error
= xfs_bmapi_read(ip
, fbno
, end
- fbno
, map
, &nmaps
, 0);
1363 if (map
[0].br_startblock
== HOLESTARTBLOCK
||
1364 map
[0].br_startblock
== DELAYSTARTBLOCK
||
1365 ISUNWRITTEN(&map
[0]))
1369 while (map
[1].br_blockcount
) {
1370 agno
= XFS_FSB_TO_AGNO(mp
, map
[1].br_startblock
);
1371 agbno
= XFS_FSB_TO_AGBNO(mp
, map
[1].br_startblock
);
1372 aglen
= map
[1].br_blockcount
;
1374 error
= xfs_reflink_find_shared(mp
, agno
, agbno
, aglen
,
1375 &rbno
, &rlen
, true);
1378 if (rbno
== NULLAGBLOCK
)
1381 /* Dirty the pages */
1382 xfs_iunlock(ip
, XFS_ILOCK_EXCL
);
1383 fpos
= XFS_FSB_TO_B(mp
, map
[1].br_startoff
+
1385 flen
= XFS_FSB_TO_B(mp
, rlen
);
1386 if (fpos
+ flen
> isize
)
1387 flen
= isize
- fpos
;
1388 error
= iomap_file_dirty(VFS_I(ip
), fpos
, flen
,
1390 xfs_ilock(ip
, XFS_ILOCK_EXCL
);
1394 map
[1].br_blockcount
-= (rbno
- agbno
+ rlen
);
1395 map
[1].br_startoff
+= (rbno
- agbno
+ rlen
);
1396 map
[1].br_startblock
+= (rbno
- agbno
+ rlen
);
1400 fbno
= map
[0].br_startoff
+ map
[0].br_blockcount
;
1406 /* Clear the inode reflink flag if there are no shared extents. */
1408 xfs_reflink_clear_inode_flag(
1409 struct xfs_inode
*ip
,
1410 struct xfs_trans
**tpp
)
1412 struct xfs_mount
*mp
= ip
->i_mount
;
1415 xfs_agnumber_t agno
;
1416 xfs_agblock_t agbno
;
1420 struct xfs_bmbt_irec map
;
1424 ASSERT(xfs_is_reflink_inode(ip
));
1427 end
= XFS_B_TO_FSB(mp
, i_size_read(VFS_I(ip
)));
1428 while (end
- fbno
> 0) {
1431 * Look for extents in the file. Skip holes, delalloc, or
1432 * unwritten extents; they can't be reflinked.
1434 error
= xfs_bmapi_read(ip
, fbno
, end
- fbno
, &map
, &nmaps
, 0);
1439 if (map
.br_startblock
== HOLESTARTBLOCK
||
1440 map
.br_startblock
== DELAYSTARTBLOCK
||
1444 agno
= XFS_FSB_TO_AGNO(mp
, map
.br_startblock
);
1445 agbno
= XFS_FSB_TO_AGBNO(mp
, map
.br_startblock
);
1446 aglen
= map
.br_blockcount
;
1448 error
= xfs_reflink_find_shared(mp
, agno
, agbno
, aglen
,
1449 &rbno
, &rlen
, false);
1452 /* Is there still a shared block here? */
1453 if (rbno
!= NULLAGBLOCK
)
1456 fbno
= map
.br_startoff
+ map
.br_blockcount
;
1460 * We didn't find any shared blocks so turn off the reflink flag.
1461 * First, get rid of any leftover CoW mappings.
1463 error
= xfs_reflink_cancel_cow_blocks(ip
, tpp
, 0, NULLFILEOFF
, true);
1467 /* Clear the inode flag. */
1468 trace_xfs_reflink_unset_inode_flag(ip
);
1469 ip
->i_d
.di_flags2
&= ~XFS_DIFLAG2_REFLINK
;
1470 xfs_inode_clear_cowblocks_tag(ip
);
1471 xfs_trans_ijoin(*tpp
, ip
, 0);
1472 xfs_trans_log_inode(*tpp
, ip
, XFS_ILOG_CORE
);
1478 * Clear the inode reflink flag if there are no shared extents and the size
1482 xfs_reflink_try_clear_inode_flag(
1483 struct xfs_inode
*ip
)
1485 struct xfs_mount
*mp
= ip
->i_mount
;
1486 struct xfs_trans
*tp
;
1489 /* Start a rolling transaction to remove the mappings */
1490 error
= xfs_trans_alloc(mp
, &M_RES(mp
)->tr_write
, 0, 0, 0, &tp
);
1494 xfs_ilock(ip
, XFS_ILOCK_EXCL
);
1495 xfs_trans_ijoin(tp
, ip
, 0);
1497 error
= xfs_reflink_clear_inode_flag(ip
, &tp
);
1501 error
= xfs_trans_commit(tp
);
1505 xfs_iunlock(ip
, XFS_ILOCK_EXCL
);
1508 xfs_trans_cancel(tp
);
1510 xfs_iunlock(ip
, XFS_ILOCK_EXCL
);
1515 * Pre-COW all shared blocks within a given byte range of a file and turn off
1516 * the reflink flag if we unshare all of the file's blocks.
1519 xfs_reflink_unshare(
1520 struct xfs_inode
*ip
,
1524 struct xfs_mount
*mp
= ip
->i_mount
;
1530 if (!xfs_is_reflink_inode(ip
))
1533 trace_xfs_reflink_unshare(ip
, offset
, len
);
1535 inode_dio_wait(VFS_I(ip
));
1537 /* Try to CoW the selected ranges */
1538 xfs_ilock(ip
, XFS_ILOCK_EXCL
);
1539 fbno
= XFS_B_TO_FSBT(mp
, offset
);
1540 isize
= i_size_read(VFS_I(ip
));
1541 end
= XFS_B_TO_FSB(mp
, offset
+ len
);
1542 error
= xfs_reflink_dirty_extents(ip
, fbno
, end
, isize
);
1545 xfs_iunlock(ip
, XFS_ILOCK_EXCL
);
1547 /* Wait for the IO to finish */
1548 error
= filemap_write_and_wait(VFS_I(ip
)->i_mapping
);
1552 /* Turn off the reflink flag if possible. */
1553 error
= xfs_reflink_try_clear_inode_flag(ip
);
1560 xfs_iunlock(ip
, XFS_ILOCK_EXCL
);
1562 trace_xfs_reflink_unshare_error(ip
, error
, _RET_IP_
);