1 // SPDX-License-Identifier: GPL-2.0+
3 * Copyright (C) 2016 Oracle. All Rights Reserved.
4 * Author: Darrick J. Wong <darrick.wong@oracle.com>
8 #include "xfs_shared.h"
9 #include "xfs_format.h"
10 #include "xfs_log_format.h"
11 #include "xfs_trans_resv.h"
12 #include "xfs_mount.h"
13 #include "xfs_defer.h"
14 #include "xfs_inode.h"
15 #include "xfs_trans.h"
17 #include "xfs_bmap_util.h"
18 #include "xfs_trace.h"
19 #include "xfs_icache.h"
20 #include "xfs_btree.h"
21 #include "xfs_refcount_btree.h"
22 #include "xfs_refcount.h"
23 #include "xfs_bmap_btree.h"
24 #include "xfs_trans_space.h"
26 #include "xfs_alloc.h"
27 #include "xfs_quota.h"
28 #include "xfs_reflink.h"
29 #include "xfs_iomap.h"
31 #include "xfs_ag_resv.h"
34 * Copy on Write of Shared Blocks
36 * XFS must preserve "the usual" file semantics even when two files share
37 * the same physical blocks. This means that a write to one file must not
38 * alter the blocks in a different file; the way that we'll do that is
39 * through the use of a copy-on-write mechanism. At a high level, that
40 * means that when we want to write to a shared block, we allocate a new
41 * block, write the data to the new block, and if that succeeds we map the
42 * new block into the file.
44 * XFS provides a "delayed allocation" mechanism that defers the allocation
45 * of disk blocks to dirty-but-not-yet-mapped file blocks as long as
46 * possible. This reduces fragmentation by enabling the filesystem to ask
47 * for bigger chunks less often, which is exactly what we want for CoW.
49 * The delalloc mechanism begins when the kernel wants to make a block
50 * writable (write_begin or page_mkwrite). If the offset is not mapped, we
51 * create a delalloc mapping, which is a regular in-core extent, but without
52 * a real startblock. (For delalloc mappings, the startblock encodes both
53 * a flag that this is a delalloc mapping, and a worst-case estimate of how
54 * many blocks might be required to put the mapping into the BMBT.) delalloc
55 * mappings are a reservation against the free space in the filesystem;
56 * adjacent mappings can also be combined into fewer larger mappings.
58 * As an optimization, the CoW extent size hint (cowextsz) creates
59 * outsized aligned delalloc reservations in the hope of landing out of
60 * order nearby CoW writes in a single extent on disk, thereby reducing
61 * fragmentation and improving future performance.
63 * D: --RRRRRRSSSRRRRRRRR--- (data fork)
64 * C: ------DDDDDDD--------- (CoW fork)
66 * When dirty pages are being written out (typically in writepage), the
67 * delalloc reservations are converted into unwritten mappings by
68 * allocating blocks and replacing the delalloc mapping with real ones.
69 * A delalloc mapping can be replaced by several unwritten ones if the
70 * free space is fragmented.
72 * D: --RRRRRRSSSRRRRRRRR---
73 * C: ------UUUUUUU---------
75 * We want to adapt the delalloc mechanism for copy-on-write, since the
76 * write paths are similar. The first two steps (creating the reservation
77 * and allocating the blocks) are exactly the same as delalloc except that
78 * the mappings must be stored in a separate CoW fork because we do not want
79 * to disturb the mapping in the data fork until we're sure that the write
80 * succeeded. IO completion in this case is the process of removing the old
81 * mapping from the data fork and moving the new mapping from the CoW fork to
82 * the data fork. This will be discussed shortly.
84 * For now, unaligned directio writes will be bounced back to the page cache.
85 * Block-aligned directio writes will use the same mechanism as buffered
88 * Just prior to submitting the actual disk write requests, we convert
89 * the extents representing the range of the file actually being written
90 * (as opposed to extra pieces created for the cowextsize hint) to real
91 * extents. This will become important in the next step:
93 * D: --RRRRRRSSSRRRRRRRR---
94 * C: ------UUrrUUU---------
96 * CoW remapping must be done after the data block write completes,
97 * because we don't want to destroy the old data fork map until we're sure
98 * the new block has been written. Since the new mappings are kept in a
99 * separate fork, we can simply iterate these mappings to find the ones
100 * that cover the file blocks that we just CoW'd. For each extent, simply
101 * unmap the corresponding range in the data fork, map the new range into
102 * the data fork, and remove the extent from the CoW fork. Because of
103 * the presence of the cowextsize hint, however, we must be careful
104 * only to remap the blocks that we've actually written out -- we must
105 * never remap delalloc reservations nor CoW staging blocks that have
106 * yet to be written. This corresponds exactly to the real extents in
109 * D: --RRRRRRrrSRRRRRRRR---
110 * C: ------UU--UUU---------
112 * Since the remapping operation can be applied to an arbitrary file
113 * range, we record the need for the remap step as a flag in the ioend
114 * instead of declaring a new IO type. This is required for direct io
115 * because we only have ioend for the whole dio, and we have to be able to
116 * remember the presence of unwritten blocks and CoW blocks with a single
117 * ioend structure. Better yet, the more ground we can cover with one
122 * Given an AG extent, find the lowest-numbered run of shared blocks
123 * within that range and return the range in fbno/flen. If
124 * find_end_of_shared is true, return the longest contiguous extent of
125 * shared blocks. If there are no shared extents, fbno and flen will
126 * be set to NULLAGBLOCK and 0, respectively.
129 xfs_reflink_find_shared(
130 struct xfs_perag
*pag
,
131 struct xfs_trans
*tp
,
136 bool find_end_of_shared
)
138 struct xfs_buf
*agbp
;
139 struct xfs_btree_cur
*cur
;
142 error
= xfs_alloc_read_agf(pag
, tp
, 0, &agbp
);
146 cur
= xfs_refcountbt_init_cursor(pag
->pag_mount
, tp
, agbp
, pag
);
148 error
= xfs_refcount_find_shared(cur
, agbno
, aglen
, fbno
, flen
,
151 xfs_btree_del_cursor(cur
, error
);
153 xfs_trans_brelse(tp
, agbp
);
158 * Trim the mapping to the next block where there's a change in the
159 * shared/unshared status. More specifically, this means that we
160 * find the lowest-numbered extent of shared blocks that coincides with
161 * the given block mapping. If the shared extent overlaps the start of
162 * the mapping, trim the mapping to the end of the shared extent. If
163 * the shared region intersects the mapping, trim the mapping to the
164 * start of the shared extent. If there are no shared regions that
165 * overlap, just return the original extent.
168 xfs_reflink_trim_around_shared(
169 struct xfs_inode
*ip
,
170 struct xfs_bmbt_irec
*irec
,
173 struct xfs_mount
*mp
= ip
->i_mount
;
174 struct xfs_perag
*pag
;
181 /* Holes, unwritten, and delalloc extents cannot be shared */
182 if (!xfs_is_cow_inode(ip
) || !xfs_bmap_is_written_extent(irec
)) {
187 trace_xfs_reflink_trim_around_shared(ip
, irec
);
189 pag
= xfs_perag_get(mp
, XFS_FSB_TO_AGNO(mp
, irec
->br_startblock
));
190 agbno
= XFS_FSB_TO_AGBNO(mp
, irec
->br_startblock
);
191 aglen
= irec
->br_blockcount
;
193 error
= xfs_reflink_find_shared(pag
, NULL
, agbno
, aglen
, &fbno
, &flen
,
200 if (fbno
== NULLAGBLOCK
) {
201 /* No shared blocks at all. */
207 * The start of this extent is shared. Truncate the
208 * mapping at the end of the shared region so that a
209 * subsequent iteration starts at the start of the
212 irec
->br_blockcount
= flen
;
218 * There's a shared extent midway through this extent.
219 * Truncate the mapping at the start of the shared
220 * extent so that a subsequent iteration starts at the
221 * start of the shared region.
223 irec
->br_blockcount
= fbno
- agbno
;
229 struct xfs_inode
*ip
,
230 struct xfs_bmbt_irec
*imap
,
233 /* We can't update any real extents in always COW mode. */
234 if (xfs_is_always_cow_inode(ip
) &&
235 !isnullstartblock(imap
->br_startblock
)) {
240 /* Trim the mapping to the nearest shared extent boundary. */
241 return xfs_reflink_trim_around_shared(ip
, imap
, shared
);
245 xfs_reflink_convert_cow_locked(
246 struct xfs_inode
*ip
,
247 xfs_fileoff_t offset_fsb
,
248 xfs_filblks_t count_fsb
)
250 struct xfs_iext_cursor icur
;
251 struct xfs_bmbt_irec got
;
252 struct xfs_btree_cur
*dummy_cur
= NULL
;
256 if (!xfs_iext_lookup_extent(ip
, ip
->i_cowfp
, offset_fsb
, &icur
, &got
))
260 if (got
.br_startoff
>= offset_fsb
+ count_fsb
)
262 if (got
.br_state
== XFS_EXT_NORM
)
264 if (WARN_ON_ONCE(isnullstartblock(got
.br_startblock
)))
267 xfs_trim_extent(&got
, offset_fsb
, count_fsb
);
268 if (!got
.br_blockcount
)
271 got
.br_state
= XFS_EXT_NORM
;
272 error
= xfs_bmap_add_extent_unwritten_real(NULL
, ip
,
273 XFS_COW_FORK
, &icur
, &dummy_cur
, &got
,
277 } while (xfs_iext_next_extent(ip
->i_cowfp
, &icur
, &got
));
282 /* Convert all of the unwritten CoW extents in a file's range to real ones. */
284 xfs_reflink_convert_cow(
285 struct xfs_inode
*ip
,
289 struct xfs_mount
*mp
= ip
->i_mount
;
290 xfs_fileoff_t offset_fsb
= XFS_B_TO_FSBT(mp
, offset
);
291 xfs_fileoff_t end_fsb
= XFS_B_TO_FSB(mp
, offset
+ count
);
292 xfs_filblks_t count_fsb
= end_fsb
- offset_fsb
;
297 xfs_ilock(ip
, XFS_ILOCK_EXCL
);
298 error
= xfs_reflink_convert_cow_locked(ip
, offset_fsb
, count_fsb
);
299 xfs_iunlock(ip
, XFS_ILOCK_EXCL
);
304 * Find the extent that maps the given range in the COW fork. Even if the extent
305 * is not shared we might have a preallocation for it in the COW fork. If so we
306 * use it that rather than trigger a new allocation.
309 xfs_find_trim_cow_extent(
310 struct xfs_inode
*ip
,
311 struct xfs_bmbt_irec
*imap
,
312 struct xfs_bmbt_irec
*cmap
,
316 xfs_fileoff_t offset_fsb
= imap
->br_startoff
;
317 xfs_filblks_t count_fsb
= imap
->br_blockcount
;
318 struct xfs_iext_cursor icur
;
323 * If we don't find an overlapping extent, trim the range we need to
324 * allocate to fit the hole we found.
326 if (!xfs_iext_lookup_extent(ip
, ip
->i_cowfp
, offset_fsb
, &icur
, cmap
))
327 cmap
->br_startoff
= offset_fsb
+ count_fsb
;
328 if (cmap
->br_startoff
> offset_fsb
) {
329 xfs_trim_extent(imap
, imap
->br_startoff
,
330 cmap
->br_startoff
- imap
->br_startoff
);
331 return xfs_bmap_trim_cow(ip
, imap
, shared
);
335 if (isnullstartblock(cmap
->br_startblock
)) {
336 xfs_trim_extent(imap
, cmap
->br_startoff
, cmap
->br_blockcount
);
340 /* real extent found - no need to allocate */
341 xfs_trim_extent(cmap
, offset_fsb
, count_fsb
);
347 xfs_reflink_convert_unwritten(
348 struct xfs_inode
*ip
,
349 struct xfs_bmbt_irec
*imap
,
350 struct xfs_bmbt_irec
*cmap
,
353 xfs_fileoff_t offset_fsb
= imap
->br_startoff
;
354 xfs_filblks_t count_fsb
= imap
->br_blockcount
;
358 * cmap might larger than imap due to cowextsize hint.
360 xfs_trim_extent(cmap
, offset_fsb
, count_fsb
);
363 * COW fork extents are supposed to remain unwritten until we're ready
364 * to initiate a disk write. For direct I/O we are going to write the
365 * data and need the conversion, but for buffered writes we're done.
367 if (!convert_now
|| cmap
->br_state
== XFS_EXT_NORM
)
370 trace_xfs_reflink_convert_cow(ip
, cmap
);
372 error
= xfs_reflink_convert_cow_locked(ip
, offset_fsb
, count_fsb
);
374 cmap
->br_state
= XFS_EXT_NORM
;
380 xfs_reflink_fill_cow_hole(
381 struct xfs_inode
*ip
,
382 struct xfs_bmbt_irec
*imap
,
383 struct xfs_bmbt_irec
*cmap
,
388 struct xfs_mount
*mp
= ip
->i_mount
;
389 struct xfs_trans
*tp
;
390 xfs_filblks_t resaligned
;
391 xfs_extlen_t resblks
;
396 resaligned
= xfs_aligned_fsb_count(imap
->br_startoff
,
397 imap
->br_blockcount
, xfs_get_cowextsz_hint(ip
));
398 resblks
= XFS_DIOSTRAT_SPACE_RES(mp
, resaligned
);
400 xfs_iunlock(ip
, *lockmode
);
403 error
= xfs_trans_alloc_inode(ip
, &M_RES(mp
)->tr_write
, resblks
, 0,
408 *lockmode
= XFS_ILOCK_EXCL
;
410 error
= xfs_find_trim_cow_extent(ip
, imap
, cmap
, shared
, &found
);
411 if (error
|| !*shared
)
412 goto out_trans_cancel
;
415 xfs_trans_cancel(tp
);
419 /* Allocate the entire reservation as unwritten blocks. */
421 error
= xfs_bmapi_write(tp
, ip
, imap
->br_startoff
, imap
->br_blockcount
,
422 XFS_BMAPI_COWFORK
| XFS_BMAPI_PREALLOC
, 0, cmap
,
425 goto out_trans_cancel
;
427 xfs_inode_set_cowblocks_tag(ip
);
428 error
= xfs_trans_commit(tp
);
433 * Allocation succeeded but the requested range was not even partially
434 * satisfied? Bail out!
440 return xfs_reflink_convert_unwritten(ip
, imap
, cmap
, convert_now
);
443 xfs_trans_cancel(tp
);
448 xfs_reflink_fill_delalloc(
449 struct xfs_inode
*ip
,
450 struct xfs_bmbt_irec
*imap
,
451 struct xfs_bmbt_irec
*cmap
,
456 struct xfs_mount
*mp
= ip
->i_mount
;
457 struct xfs_trans
*tp
;
463 xfs_iunlock(ip
, *lockmode
);
466 error
= xfs_trans_alloc_inode(ip
, &M_RES(mp
)->tr_write
, 0, 0,
471 *lockmode
= XFS_ILOCK_EXCL
;
473 error
= xfs_find_trim_cow_extent(ip
, imap
, cmap
, shared
,
475 if (error
|| !*shared
)
476 goto out_trans_cancel
;
479 xfs_trans_cancel(tp
);
483 ASSERT(isnullstartblock(cmap
->br_startblock
) ||
484 cmap
->br_startblock
== DELAYSTARTBLOCK
);
487 * Replace delalloc reservation with an unwritten extent.
490 error
= xfs_bmapi_write(tp
, ip
, cmap
->br_startoff
,
492 XFS_BMAPI_COWFORK
| XFS_BMAPI_PREALLOC
, 0,
495 goto out_trans_cancel
;
497 xfs_inode_set_cowblocks_tag(ip
);
498 error
= xfs_trans_commit(tp
);
503 * Allocation succeeded but the requested range was not even
504 * partially satisfied? Bail out!
508 } while (cmap
->br_startoff
+ cmap
->br_blockcount
<= imap
->br_startoff
);
510 return xfs_reflink_convert_unwritten(ip
, imap
, cmap
, convert_now
);
513 xfs_trans_cancel(tp
);
517 /* Allocate all CoW reservations covering a range of blocks in a file. */
519 xfs_reflink_allocate_cow(
520 struct xfs_inode
*ip
,
521 struct xfs_bmbt_irec
*imap
,
522 struct xfs_bmbt_irec
*cmap
,
530 ASSERT(xfs_isilocked(ip
, XFS_ILOCK_EXCL
));
532 ASSERT(!xfs_is_reflink_inode(ip
));
533 xfs_ifork_init_cow(ip
);
536 error
= xfs_find_trim_cow_extent(ip
, imap
, cmap
, shared
, &found
);
537 if (error
|| !*shared
)
540 /* CoW fork has a real extent */
542 return xfs_reflink_convert_unwritten(ip
, imap
, cmap
,
546 * CoW fork does not have an extent and data extent is shared.
547 * Allocate a real extent in the CoW fork.
549 if (cmap
->br_startoff
> imap
->br_startoff
)
550 return xfs_reflink_fill_cow_hole(ip
, imap
, cmap
, shared
,
551 lockmode
, convert_now
);
554 * CoW fork has a delalloc reservation. Replace it with a real extent.
555 * There may or may not be a data fork mapping.
557 if (isnullstartblock(cmap
->br_startblock
) ||
558 cmap
->br_startblock
== DELAYSTARTBLOCK
)
559 return xfs_reflink_fill_delalloc(ip
, imap
, cmap
, shared
,
560 lockmode
, convert_now
);
562 /* Shouldn't get here. */
564 return -EFSCORRUPTED
;
568 * Cancel CoW reservations for some block range of an inode.
570 * If cancel_real is true this function cancels all COW fork extents for the
571 * inode; if cancel_real is false, real extents are not cleared.
573 * Caller must have already joined the inode to the current transaction. The
574 * inode will be joined to the transaction returned to the caller.
577 xfs_reflink_cancel_cow_blocks(
578 struct xfs_inode
*ip
,
579 struct xfs_trans
**tpp
,
580 xfs_fileoff_t offset_fsb
,
581 xfs_fileoff_t end_fsb
,
584 struct xfs_ifork
*ifp
= xfs_ifork_ptr(ip
, XFS_COW_FORK
);
585 struct xfs_bmbt_irec got
, del
;
586 struct xfs_iext_cursor icur
;
589 if (!xfs_inode_has_cow_data(ip
))
591 if (!xfs_iext_lookup_extent_before(ip
, ifp
, &end_fsb
, &icur
, &got
))
594 /* Walk backwards until we're out of the I/O range... */
595 while (got
.br_startoff
+ got
.br_blockcount
> offset_fsb
) {
597 xfs_trim_extent(&del
, offset_fsb
, end_fsb
- offset_fsb
);
599 /* Extent delete may have bumped ext forward */
600 if (!del
.br_blockcount
) {
601 xfs_iext_prev(ifp
, &icur
);
605 trace_xfs_reflink_cancel_cow(ip
, &del
);
607 if (isnullstartblock(del
.br_startblock
)) {
608 error
= xfs_bmap_del_extent_delay(ip
, XFS_COW_FORK
,
612 } else if (del
.br_state
== XFS_EXT_UNWRITTEN
|| cancel_real
) {
613 ASSERT((*tpp
)->t_highest_agno
== NULLAGNUMBER
);
615 /* Free the CoW orphan record. */
616 xfs_refcount_free_cow_extent(*tpp
, del
.br_startblock
,
619 error
= xfs_free_extent_later(*tpp
, del
.br_startblock
,
620 del
.br_blockcount
, NULL
,
625 /* Roll the transaction */
626 error
= xfs_defer_finish(tpp
);
630 /* Remove the mapping from the CoW fork. */
631 xfs_bmap_del_extent_cow(ip
, &icur
, &got
, &del
);
633 /* Remove the quota reservation */
634 error
= xfs_quota_unreserve_blkres(ip
,
639 /* Didn't do anything, push cursor back. */
640 xfs_iext_prev(ifp
, &icur
);
643 if (!xfs_iext_get_extent(ifp
, &icur
, &got
))
647 /* clear tag if cow fork is emptied */
649 xfs_inode_clear_cowblocks_tag(ip
);
654 * Cancel CoW reservations for some byte range of an inode.
656 * If cancel_real is true this function cancels all COW fork extents for the
657 * inode; if cancel_real is false, real extents are not cleared.
660 xfs_reflink_cancel_cow_range(
661 struct xfs_inode
*ip
,
666 struct xfs_trans
*tp
;
667 xfs_fileoff_t offset_fsb
;
668 xfs_fileoff_t end_fsb
;
671 trace_xfs_reflink_cancel_cow_range(ip
, offset
, count
);
674 offset_fsb
= XFS_B_TO_FSBT(ip
->i_mount
, offset
);
675 if (count
== NULLFILEOFF
)
676 end_fsb
= NULLFILEOFF
;
678 end_fsb
= XFS_B_TO_FSB(ip
->i_mount
, offset
+ count
);
680 /* Start a rolling transaction to remove the mappings */
681 error
= xfs_trans_alloc(ip
->i_mount
, &M_RES(ip
->i_mount
)->tr_write
,
686 xfs_ilock(ip
, XFS_ILOCK_EXCL
);
687 xfs_trans_ijoin(tp
, ip
, 0);
689 /* Scrape out the old CoW reservations */
690 error
= xfs_reflink_cancel_cow_blocks(ip
, &tp
, offset_fsb
, end_fsb
,
695 error
= xfs_trans_commit(tp
);
697 xfs_iunlock(ip
, XFS_ILOCK_EXCL
);
701 xfs_trans_cancel(tp
);
702 xfs_iunlock(ip
, XFS_ILOCK_EXCL
);
704 trace_xfs_reflink_cancel_cow_range_error(ip
, error
, _RET_IP_
);
709 * Remap part of the CoW fork into the data fork.
711 * We aim to remap the range starting at @offset_fsb and ending at @end_fsb
712 * into the data fork; this function will remap what it can (at the end of the
713 * range) and update @end_fsb appropriately. Each remap gets its own
714 * transaction because we can end up merging and splitting bmbt blocks for
715 * every remap operation and we'd like to keep the block reservation
716 * requirements as low as possible.
719 xfs_reflink_end_cow_extent(
720 struct xfs_inode
*ip
,
721 xfs_fileoff_t
*offset_fsb
,
722 xfs_fileoff_t end_fsb
)
724 struct xfs_iext_cursor icur
;
725 struct xfs_bmbt_irec got
, del
, data
;
726 struct xfs_mount
*mp
= ip
->i_mount
;
727 struct xfs_trans
*tp
;
728 struct xfs_ifork
*ifp
= xfs_ifork_ptr(ip
, XFS_COW_FORK
);
729 unsigned int resblks
;
733 /* No COW extents? That's easy! */
734 if (ifp
->if_bytes
== 0) {
735 *offset_fsb
= end_fsb
;
739 resblks
= XFS_EXTENTADD_SPACE_RES(mp
, XFS_DATA_FORK
);
740 error
= xfs_trans_alloc(mp
, &M_RES(mp
)->tr_write
, resblks
, 0,
741 XFS_TRANS_RESERVE
, &tp
);
746 * Lock the inode. We have to ijoin without automatic unlock because
747 * the lead transaction is the refcountbt record deletion; the data
748 * fork update follows as a deferred log item.
750 xfs_ilock(ip
, XFS_ILOCK_EXCL
);
751 xfs_trans_ijoin(tp
, ip
, 0);
753 error
= xfs_iext_count_may_overflow(ip
, XFS_DATA_FORK
,
754 XFS_IEXT_REFLINK_END_COW_CNT
);
756 error
= xfs_iext_count_upgrade(tp
, ip
,
757 XFS_IEXT_REFLINK_END_COW_CNT
);
762 * In case of racing, overlapping AIO writes no COW extents might be
763 * left by the time I/O completes for the loser of the race. In that
766 if (!xfs_iext_lookup_extent(ip
, ifp
, *offset_fsb
, &icur
, &got
) ||
767 got
.br_startoff
>= end_fsb
) {
768 *offset_fsb
= end_fsb
;
773 * Only remap real extents that contain data. With AIO, speculative
774 * preallocations can leak into the range we are called upon, and we
775 * need to skip them. Preserve @got for the eventual CoW fork
776 * deletion; from now on @del represents the mapping that we're
777 * actually remapping.
779 while (!xfs_bmap_is_written_extent(&got
)) {
780 if (!xfs_iext_next_extent(ifp
, &icur
, &got
) ||
781 got
.br_startoff
>= end_fsb
) {
782 *offset_fsb
= end_fsb
;
787 xfs_trim_extent(&del
, *offset_fsb
, end_fsb
- *offset_fsb
);
789 /* Grab the corresponding mapping in the data fork. */
791 error
= xfs_bmapi_read(ip
, del
.br_startoff
, del
.br_blockcount
, &data
,
796 /* We can only remap the smaller of the two extent sizes. */
797 data
.br_blockcount
= min(data
.br_blockcount
, del
.br_blockcount
);
798 del
.br_blockcount
= data
.br_blockcount
;
800 trace_xfs_reflink_cow_remap_from(ip
, &del
);
801 trace_xfs_reflink_cow_remap_to(ip
, &data
);
803 if (xfs_bmap_is_real_extent(&data
)) {
805 * If the extent we're remapping is backed by storage (written
806 * or not), unmap the extent and drop its refcount.
808 xfs_bmap_unmap_extent(tp
, ip
, &data
);
809 xfs_refcount_decrease_extent(tp
, &data
);
810 xfs_trans_mod_dquot_byino(tp
, ip
, XFS_TRANS_DQ_BCOUNT
,
811 -data
.br_blockcount
);
812 } else if (data
.br_startblock
== DELAYSTARTBLOCK
) {
816 * If the extent we're remapping is a delalloc reservation,
817 * we can use the regular bunmapi function to release the
818 * incore state. Dropping the delalloc reservation takes care
819 * of the quota reservation for us.
821 error
= xfs_bunmapi(NULL
, ip
, data
.br_startoff
,
822 data
.br_blockcount
, 0, 1, &done
);
828 /* Free the CoW orphan record. */
829 xfs_refcount_free_cow_extent(tp
, del
.br_startblock
, del
.br_blockcount
);
831 /* Map the new blocks into the data fork. */
832 xfs_bmap_map_extent(tp
, ip
, &del
);
834 /* Charge this new data fork mapping to the on-disk quota. */
835 xfs_trans_mod_dquot_byino(tp
, ip
, XFS_TRANS_DQ_DELBCOUNT
,
836 (long)del
.br_blockcount
);
838 /* Remove the mapping from the CoW fork. */
839 xfs_bmap_del_extent_cow(ip
, &icur
, &got
, &del
);
841 error
= xfs_trans_commit(tp
);
842 xfs_iunlock(ip
, XFS_ILOCK_EXCL
);
846 /* Update the caller about how much progress we made. */
847 *offset_fsb
= del
.br_startoff
+ del
.br_blockcount
;
851 xfs_trans_cancel(tp
);
852 xfs_iunlock(ip
, XFS_ILOCK_EXCL
);
857 * Remap parts of a file's data fork after a successful CoW.
861 struct xfs_inode
*ip
,
865 xfs_fileoff_t offset_fsb
;
866 xfs_fileoff_t end_fsb
;
869 trace_xfs_reflink_end_cow(ip
, offset
, count
);
871 offset_fsb
= XFS_B_TO_FSBT(ip
->i_mount
, offset
);
872 end_fsb
= XFS_B_TO_FSB(ip
->i_mount
, offset
+ count
);
875 * Walk forwards until we've remapped the I/O range. The loop function
876 * repeatedly cycles the ILOCK to allocate one transaction per remapped
879 * If we're being called by writeback then the pages will still
880 * have PageWriteback set, which prevents races with reflink remapping
881 * and truncate. Reflink remapping prevents races with writeback by
882 * taking the iolock and mmaplock before flushing the pages and
883 * remapping, which means there won't be any further writeback or page
884 * cache dirtying until the reflink completes.
886 * We should never have two threads issuing writeback for the same file
887 * region. There are also have post-eof checks in the writeback
888 * preparation code so that we don't bother writing out pages that are
889 * about to be truncated.
891 * If we're being called as part of directio write completion, the dio
892 * count is still elevated, which reflink and truncate will wait for.
893 * Reflink remapping takes the iolock and mmaplock and waits for
894 * pending dio to finish, which should prevent any directio until the
895 * remap completes. Multiple concurrent directio writes to the same
896 * region are handled by end_cow processing only occurring for the
897 * threads which succeed; the outcome of multiple overlapping direct
898 * writes is not well defined anyway.
900 * It's possible that a buffered write and a direct write could collide
901 * here (the buffered write stumbles in after the dio flushes and
902 * invalidates the page cache and immediately queues writeback), but we
903 * have never supported this 100%. If either disk write succeeds the
904 * blocks will be remapped.
906 while (end_fsb
> offset_fsb
&& !error
)
907 error
= xfs_reflink_end_cow_extent(ip
, &offset_fsb
, end_fsb
);
910 trace_xfs_reflink_end_cow_error(ip
, error
, _RET_IP_
);
915 * Free all CoW staging blocks that are still referenced by the ondisk refcount
916 * metadata. The ondisk metadata does not track which inode created the
917 * staging extent, so callers must ensure that there are no cached inodes with
918 * live CoW staging extents.
921 xfs_reflink_recover_cow(
922 struct xfs_mount
*mp
)
924 struct xfs_perag
*pag
;
928 if (!xfs_has_reflink(mp
))
931 for_each_perag(mp
, agno
, pag
) {
932 error
= xfs_refcount_recover_cow_leftovers(mp
, pag
);
943 * Reflinking (Block) Ranges of Two Files Together
945 * First, ensure that the reflink flag is set on both inodes. The flag is an
946 * optimization to avoid unnecessary refcount btree lookups in the write path.
948 * Now we can iteratively remap the range of extents (and holes) in src to the
949 * corresponding ranges in dest. Let drange and srange denote the ranges of
950 * logical blocks in dest and src touched by the reflink operation.
952 * While the length of drange is greater than zero,
953 * - Read src's bmbt at the start of srange ("imap")
954 * - If imap doesn't exist, make imap appear to start at the end of srange
956 * - If imap starts before srange, advance imap to start at srange.
957 * - If imap goes beyond srange, truncate imap to end at the end of srange.
958 * - Punch (imap start - srange start + imap len) blocks from dest at
959 * offset (drange start).
960 * - If imap points to a real range of pblks,
961 * > Increase the refcount of the imap's pblks
962 * > Map imap's pblks into dest at the offset
963 * (drange start + imap start - srange start)
964 * - Advance drange and srange by (imap start - srange start + imap len)
966 * Finally, if the reflink made dest longer, update both the in-core and
967 * on-disk file sizes.
969 * ASCII Art Demonstration:
971 * Let's say we want to reflink this source file:
973 * ----SSSSSSS-SSSSS----SSSSSS (src file)
974 * <-------------------->
976 * into this destination file:
978 * --DDDDDDDDDDDDDDDDDDD--DDD (dest file)
979 * <-------------------->
980 * '-' means a hole, and 'S' and 'D' are written blocks in the src and dest.
981 * Observe that the range has different logical offsets in either file.
983 * Consider that the first extent in the source file doesn't line up with our
984 * reflink range. Unmapping and remapping are separate operations, so we can
985 * unmap more blocks from the destination file than we remap.
987 * ----SSSSSSS-SSSSS----SSSSSS
989 * --DDDDD---------DDDDD--DDD
992 * Now remap the source extent into the destination file:
994 * ----SSSSSSS-SSSSS----SSSSSS
996 * --DDDDD--SSSSSSSDDDDD--DDD
999 * Do likewise with the second hole and extent in our range. Holes in the
1000 * unmap range don't affect our operation.
1002 * ----SSSSSSS-SSSSS----SSSSSS
1004 * --DDDDD--SSSSSSS-SSSSS-DDD
1007 * Finally, unmap and remap part of the third extent. This will increase the
1008 * size of the destination file.
1010 * ----SSSSSSS-SSSSS----SSSSSS
1012 * --DDDDD--SSSSSSS-SSSSS----SSS
1015 * Once we update the destination file's i_size, we're done.
1019 * Ensure the reflink bit is set in both inodes.
1022 xfs_reflink_set_inode_flag(
1023 struct xfs_inode
*src
,
1024 struct xfs_inode
*dest
)
1026 struct xfs_mount
*mp
= src
->i_mount
;
1028 struct xfs_trans
*tp
;
1030 if (xfs_is_reflink_inode(src
) && xfs_is_reflink_inode(dest
))
1033 error
= xfs_trans_alloc(mp
, &M_RES(mp
)->tr_ichange
, 0, 0, 0, &tp
);
1037 /* Lock both files against IO */
1038 if (src
->i_ino
== dest
->i_ino
)
1039 xfs_ilock(src
, XFS_ILOCK_EXCL
);
1041 xfs_lock_two_inodes(src
, XFS_ILOCK_EXCL
, dest
, XFS_ILOCK_EXCL
);
1043 if (!xfs_is_reflink_inode(src
)) {
1044 trace_xfs_reflink_set_inode_flag(src
);
1045 xfs_trans_ijoin(tp
, src
, XFS_ILOCK_EXCL
);
1046 src
->i_diflags2
|= XFS_DIFLAG2_REFLINK
;
1047 xfs_trans_log_inode(tp
, src
, XFS_ILOG_CORE
);
1048 xfs_ifork_init_cow(src
);
1050 xfs_iunlock(src
, XFS_ILOCK_EXCL
);
1052 if (src
->i_ino
== dest
->i_ino
)
1055 if (!xfs_is_reflink_inode(dest
)) {
1056 trace_xfs_reflink_set_inode_flag(dest
);
1057 xfs_trans_ijoin(tp
, dest
, XFS_ILOCK_EXCL
);
1058 dest
->i_diflags2
|= XFS_DIFLAG2_REFLINK
;
1059 xfs_trans_log_inode(tp
, dest
, XFS_ILOG_CORE
);
1060 xfs_ifork_init_cow(dest
);
1062 xfs_iunlock(dest
, XFS_ILOCK_EXCL
);
1065 error
= xfs_trans_commit(tp
);
1071 trace_xfs_reflink_set_inode_flag_error(dest
, error
, _RET_IP_
);
1076 * Update destination inode size & cowextsize hint, if necessary.
1079 xfs_reflink_update_dest(
1080 struct xfs_inode
*dest
,
1082 xfs_extlen_t cowextsize
,
1083 unsigned int remap_flags
)
1085 struct xfs_mount
*mp
= dest
->i_mount
;
1086 struct xfs_trans
*tp
;
1089 if (newlen
<= i_size_read(VFS_I(dest
)) && cowextsize
== 0)
1092 error
= xfs_trans_alloc(mp
, &M_RES(mp
)->tr_ichange
, 0, 0, 0, &tp
);
1096 xfs_ilock(dest
, XFS_ILOCK_EXCL
);
1097 xfs_trans_ijoin(tp
, dest
, XFS_ILOCK_EXCL
);
1099 if (newlen
> i_size_read(VFS_I(dest
))) {
1100 trace_xfs_reflink_update_inode_size(dest
, newlen
);
1101 i_size_write(VFS_I(dest
), newlen
);
1102 dest
->i_disk_size
= newlen
;
1106 dest
->i_cowextsize
= cowextsize
;
1107 dest
->i_diflags2
|= XFS_DIFLAG2_COWEXTSIZE
;
1110 xfs_trans_log_inode(tp
, dest
, XFS_ILOG_CORE
);
1112 error
= xfs_trans_commit(tp
);
1118 trace_xfs_reflink_update_inode_size_error(dest
, error
, _RET_IP_
);
1123 * Do we have enough reserve in this AG to handle a reflink? The refcount
1124 * btree already reserved all the space it needs, but the rmap btree can grow
1125 * infinitely, so we won't allow more reflinks when the AG is down to the
1129 xfs_reflink_ag_has_free_space(
1130 struct xfs_mount
*mp
,
1131 xfs_agnumber_t agno
)
1133 struct xfs_perag
*pag
;
1136 if (!xfs_has_rmapbt(mp
))
1139 pag
= xfs_perag_get(mp
, agno
);
1140 if (xfs_ag_resv_critical(pag
, XFS_AG_RESV_RMAPBT
) ||
1141 xfs_ag_resv_critical(pag
, XFS_AG_RESV_METADATA
))
1148 * Remap the given extent into the file. The dmap blockcount will be set to
1149 * the number of blocks that were actually remapped.
1152 xfs_reflink_remap_extent(
1153 struct xfs_inode
*ip
,
1154 struct xfs_bmbt_irec
*dmap
,
1155 xfs_off_t new_isize
)
1157 struct xfs_bmbt_irec smap
;
1158 struct xfs_mount
*mp
= ip
->i_mount
;
1159 struct xfs_trans
*tp
;
1162 unsigned int resblks
;
1163 bool quota_reserved
= true;
1165 bool dmap_written
= xfs_bmap_is_written_extent(dmap
);
1171 * Start a rolling transaction to switch the mappings.
1173 * Adding a written extent to the extent map can cause a bmbt split,
1174 * and removing a mapped extent from the extent can cause a bmbt split.
1175 * The two operations cannot both cause a split since they operate on
1176 * the same index in the bmap btree, so we only need a reservation for
1177 * one bmbt split if either thing is happening. However, we haven't
1178 * locked the inode yet, so we reserve assuming this is the case.
1180 * The first allocation call tries to reserve enough space to handle
1181 * mapping dmap into a sparse part of the file plus the bmbt split. We
1182 * haven't locked the inode or read the existing mapping yet, so we do
1183 * not know for sure that we need the space. This should succeed most
1186 * If the first attempt fails, try again but reserving only enough
1187 * space to handle a bmbt split. This is the hard minimum requirement,
1188 * and we revisit quota reservations later when we know more about what
1191 resblks
= XFS_EXTENTADD_SPACE_RES(mp
, XFS_DATA_FORK
);
1192 error
= xfs_trans_alloc_inode(ip
, &M_RES(mp
)->tr_write
,
1193 resblks
+ dmap
->br_blockcount
, 0, false, &tp
);
1194 if (error
== -EDQUOT
|| error
== -ENOSPC
) {
1195 quota_reserved
= false;
1196 error
= xfs_trans_alloc_inode(ip
, &M_RES(mp
)->tr_write
,
1197 resblks
, 0, false, &tp
);
1203 * Read what's currently mapped in the destination file into smap.
1204 * If smap isn't a hole, we will have to remove it before we can add
1205 * dmap to the destination file.
1208 error
= xfs_bmapi_read(ip
, dmap
->br_startoff
, dmap
->br_blockcount
,
1212 ASSERT(nimaps
== 1 && smap
.br_startoff
== dmap
->br_startoff
);
1213 smap_real
= xfs_bmap_is_real_extent(&smap
);
1216 * We can only remap as many blocks as the smaller of the two extent
1217 * maps, because we can only remap one extent at a time.
1219 dmap
->br_blockcount
= min(dmap
->br_blockcount
, smap
.br_blockcount
);
1220 ASSERT(dmap
->br_blockcount
== smap
.br_blockcount
);
1222 trace_xfs_reflink_remap_extent_dest(ip
, &smap
);
1225 * Two extents mapped to the same physical block must not have
1226 * different states; that's filesystem corruption. Move on to the next
1227 * extent if they're both holes or both the same physical extent.
1229 if (dmap
->br_startblock
== smap
.br_startblock
) {
1230 if (dmap
->br_state
!= smap
.br_state
)
1231 error
= -EFSCORRUPTED
;
1235 /* If both extents are unwritten, leave them alone. */
1236 if (dmap
->br_state
== XFS_EXT_UNWRITTEN
&&
1237 smap
.br_state
== XFS_EXT_UNWRITTEN
)
1240 /* No reflinking if the AG of the dest mapping is low on space. */
1242 error
= xfs_reflink_ag_has_free_space(mp
,
1243 XFS_FSB_TO_AGNO(mp
, dmap
->br_startblock
));
1249 * Increase quota reservation if we think the quota block counter for
1250 * this file could increase.
1252 * If we are mapping a written extent into the file, we need to have
1253 * enough quota block count reservation to handle the blocks in that
1254 * extent. We log only the delta to the quota block counts, so if the
1255 * extent we're unmapping also has blocks allocated to it, we don't
1256 * need a quota reservation for the extent itself.
1258 * Note that if we're replacing a delalloc reservation with a written
1259 * extent, we have to take the full quota reservation because removing
1260 * the delalloc reservation gives the block count back to the quota
1261 * count. This is suboptimal, but the VFS flushed the dest range
1262 * before we started. That should have removed all the delalloc
1263 * reservations, but we code defensively.
1265 * xfs_trans_alloc_inode above already tried to grab an even larger
1266 * quota reservation, and kicked off a blockgc scan if it couldn't.
1267 * If we can't get a potentially smaller quota reservation now, we're
1270 if (!quota_reserved
&& !smap_real
&& dmap_written
) {
1271 error
= xfs_trans_reserve_quota_nblks(tp
, ip
,
1272 dmap
->br_blockcount
, 0, false);
1283 error
= xfs_iext_count_may_overflow(ip
, XFS_DATA_FORK
, iext_delta
);
1284 if (error
== -EFBIG
)
1285 error
= xfs_iext_count_upgrade(tp
, ip
, iext_delta
);
1291 * If the extent we're unmapping is backed by storage (written
1292 * or not), unmap the extent and drop its refcount.
1294 xfs_bmap_unmap_extent(tp
, ip
, &smap
);
1295 xfs_refcount_decrease_extent(tp
, &smap
);
1296 qdelta
-= smap
.br_blockcount
;
1297 } else if (smap
.br_startblock
== DELAYSTARTBLOCK
) {
1301 * If the extent we're unmapping is a delalloc reservation,
1302 * we can use the regular bunmapi function to release the
1303 * incore state. Dropping the delalloc reservation takes care
1304 * of the quota reservation for us.
1306 error
= xfs_bunmapi(NULL
, ip
, smap
.br_startoff
,
1307 smap
.br_blockcount
, 0, 1, &done
);
1314 * If the extent we're sharing is backed by written storage, increase
1315 * its refcount and map it into the file.
1318 xfs_refcount_increase_extent(tp
, dmap
);
1319 xfs_bmap_map_extent(tp
, ip
, dmap
);
1320 qdelta
+= dmap
->br_blockcount
;
1323 xfs_trans_mod_dquot_byino(tp
, ip
, XFS_TRANS_DQ_BCOUNT
, qdelta
);
1325 /* Update dest isize if needed. */
1326 newlen
= XFS_FSB_TO_B(mp
, dmap
->br_startoff
+ dmap
->br_blockcount
);
1327 newlen
= min_t(xfs_off_t
, newlen
, new_isize
);
1328 if (newlen
> i_size_read(VFS_I(ip
))) {
1329 trace_xfs_reflink_update_inode_size(ip
, newlen
);
1330 i_size_write(VFS_I(ip
), newlen
);
1331 ip
->i_disk_size
= newlen
;
1332 xfs_trans_log_inode(tp
, ip
, XFS_ILOG_CORE
);
1335 /* Commit everything and unlock. */
1336 error
= xfs_trans_commit(tp
);
1340 xfs_trans_cancel(tp
);
1342 xfs_iunlock(ip
, XFS_ILOCK_EXCL
);
1345 trace_xfs_reflink_remap_extent_error(ip
, error
, _RET_IP_
);
1349 /* Remap a range of one file to the other. */
1351 xfs_reflink_remap_blocks(
1352 struct xfs_inode
*src
,
1354 struct xfs_inode
*dest
,
1359 struct xfs_bmbt_irec imap
;
1360 struct xfs_mount
*mp
= src
->i_mount
;
1361 xfs_fileoff_t srcoff
= XFS_B_TO_FSBT(mp
, pos_in
);
1362 xfs_fileoff_t destoff
= XFS_B_TO_FSBT(mp
, pos_out
);
1364 xfs_filblks_t remapped_len
= 0;
1365 xfs_off_t new_isize
= pos_out
+ remap_len
;
1369 len
= min_t(xfs_filblks_t
, XFS_B_TO_FSB(mp
, remap_len
),
1372 trace_xfs_reflink_remap_blocks(src
, srcoff
, len
, dest
, destoff
);
1375 unsigned int lock_mode
;
1377 /* Read extent from the source file */
1379 lock_mode
= xfs_ilock_data_map_shared(src
);
1380 error
= xfs_bmapi_read(src
, srcoff
, len
, &imap
, &nimaps
, 0);
1381 xfs_iunlock(src
, lock_mode
);
1385 * The caller supposedly flushed all dirty pages in the source
1386 * file range, which means that writeback should have allocated
1387 * or deleted all delalloc reservations in that range. If we
1388 * find one, that's a good sign that something is seriously
1391 ASSERT(nimaps
== 1 && imap
.br_startoff
== srcoff
);
1392 if (imap
.br_startblock
== DELAYSTARTBLOCK
) {
1393 ASSERT(imap
.br_startblock
!= DELAYSTARTBLOCK
);
1394 error
= -EFSCORRUPTED
;
1398 trace_xfs_reflink_remap_extent_src(src
, &imap
);
1400 /* Remap into the destination file at the given offset. */
1401 imap
.br_startoff
= destoff
;
1402 error
= xfs_reflink_remap_extent(dest
, &imap
, new_isize
);
1406 if (fatal_signal_pending(current
)) {
1411 /* Advance drange/srange */
1412 srcoff
+= imap
.br_blockcount
;
1413 destoff
+= imap
.br_blockcount
;
1414 len
-= imap
.br_blockcount
;
1415 remapped_len
+= imap
.br_blockcount
;
1419 trace_xfs_reflink_remap_blocks_error(dest
, error
, _RET_IP_
);
1420 *remapped
= min_t(loff_t
, remap_len
,
1421 XFS_FSB_TO_B(src
->i_mount
, remapped_len
));
1426 * If we're reflinking to a point past the destination file's EOF, we must
1427 * zero any speculative post-EOF preallocations that sit between the old EOF
1428 * and the destination file offset.
1431 xfs_reflink_zero_posteof(
1432 struct xfs_inode
*ip
,
1435 loff_t isize
= i_size_read(VFS_I(ip
));
1440 trace_xfs_zero_eof(ip
, isize
, pos
- isize
);
1441 return xfs_zero_range(ip
, isize
, pos
- isize
, NULL
);
1445 * Prepare two files for range cloning. Upon a successful return both inodes
1446 * will have the iolock and mmaplock held, the page cache of the out file will
1447 * be truncated, and any leases on the out file will have been broken. This
1448 * function borrows heavily from xfs_file_aio_write_checks.
1450 * The VFS allows partial EOF blocks to "match" for dedupe even though it hasn't
1451 * checked that the bytes beyond EOF physically match. Hence we cannot use the
1452 * EOF block in the source dedupe range because it's not a complete block match,
1453 * hence can introduce a corruption into the file that has it's block replaced.
1455 * In similar fashion, the VFS file cloning also allows partial EOF blocks to be
1456 * "block aligned" for the purposes of cloning entire files. However, if the
1457 * source file range includes the EOF block and it lands within the existing EOF
1458 * of the destination file, then we can expose stale data from beyond the source
1459 * file EOF in the destination file.
1461 * XFS doesn't support partial block sharing, so in both cases we have check
1462 * these cases ourselves. For dedupe, we can simply round the length to dedupe
1463 * down to the previous whole block and ignore the partial EOF block. While this
1464 * means we can't dedupe the last block of a file, this is an acceptible
1465 * tradeoff for simplicity on implementation.
1467 * For cloning, we want to share the partial EOF block if it is also the new EOF
1468 * block of the destination file. If the partial EOF block lies inside the
1469 * existing destination EOF, then we have to abort the clone to avoid exposing
1470 * stale data in the destination file. Hence we reject these clone attempts with
1471 * -EINVAL in this case.
1474 xfs_reflink_remap_prep(
1475 struct file
*file_in
,
1477 struct file
*file_out
,
1480 unsigned int remap_flags
)
1482 struct inode
*inode_in
= file_inode(file_in
);
1483 struct xfs_inode
*src
= XFS_I(inode_in
);
1484 struct inode
*inode_out
= file_inode(file_out
);
1485 struct xfs_inode
*dest
= XFS_I(inode_out
);
1488 /* Lock both files against IO */
1489 ret
= xfs_ilock2_io_mmap(src
, dest
);
1493 /* Check file eligibility and prepare for block sharing. */
1495 /* Don't reflink realtime inodes */
1496 if (XFS_IS_REALTIME_INODE(src
) || XFS_IS_REALTIME_INODE(dest
))
1499 /* Don't share DAX file data with non-DAX file. */
1500 if (IS_DAX(inode_in
) != IS_DAX(inode_out
))
1503 if (!IS_DAX(inode_in
))
1504 ret
= generic_remap_file_range_prep(file_in
, pos_in
, file_out
,
1505 pos_out
, len
, remap_flags
);
1507 ret
= dax_remap_file_range_prep(file_in
, pos_in
, file_out
,
1508 pos_out
, len
, remap_flags
, &xfs_read_iomap_ops
);
1509 if (ret
|| *len
== 0)
1512 /* Attach dquots to dest inode before changing block map */
1513 ret
= xfs_qm_dqattach(dest
);
1518 * Zero existing post-eof speculative preallocations in the destination
1521 ret
= xfs_reflink_zero_posteof(dest
, pos_out
);
1525 /* Set flags and remap blocks. */
1526 ret
= xfs_reflink_set_inode_flag(src
, dest
);
1531 * If pos_out > EOF, we may have dirtied blocks between EOF and
1532 * pos_out. In that case, we need to extend the flush and unmap to cover
1533 * from EOF to the end of the copy length.
1535 if (pos_out
> XFS_ISIZE(dest
)) {
1536 loff_t flen
= *len
+ (pos_out
- XFS_ISIZE(dest
));
1537 ret
= xfs_flush_unmap_range(dest
, XFS_ISIZE(dest
), flen
);
1539 ret
= xfs_flush_unmap_range(dest
, pos_out
, *len
);
1544 xfs_iflags_set(src
, XFS_IREMAPPING
);
1545 if (inode_in
!= inode_out
)
1546 xfs_ilock_demote(src
, XFS_IOLOCK_EXCL
| XFS_MMAPLOCK_EXCL
);
1550 xfs_iunlock2_io_mmap(src
, dest
);
1554 /* Does this inode need the reflink flag? */
1556 xfs_reflink_inode_has_shared_extents(
1557 struct xfs_trans
*tp
,
1558 struct xfs_inode
*ip
,
1561 struct xfs_bmbt_irec got
;
1562 struct xfs_mount
*mp
= ip
->i_mount
;
1563 struct xfs_ifork
*ifp
;
1564 struct xfs_iext_cursor icur
;
1568 ifp
= xfs_ifork_ptr(ip
, XFS_DATA_FORK
);
1569 error
= xfs_iread_extents(tp
, ip
, XFS_DATA_FORK
);
1573 *has_shared
= false;
1574 found
= xfs_iext_lookup_extent(ip
, ifp
, 0, &icur
, &got
);
1576 struct xfs_perag
*pag
;
1577 xfs_agblock_t agbno
;
1582 if (isnullstartblock(got
.br_startblock
) ||
1583 got
.br_state
!= XFS_EXT_NORM
)
1586 pag
= xfs_perag_get(mp
, XFS_FSB_TO_AGNO(mp
, got
.br_startblock
));
1587 agbno
= XFS_FSB_TO_AGBNO(mp
, got
.br_startblock
);
1588 aglen
= got
.br_blockcount
;
1589 error
= xfs_reflink_find_shared(pag
, tp
, agbno
, aglen
,
1590 &rbno
, &rlen
, false);
1595 /* Is there still a shared block here? */
1596 if (rbno
!= NULLAGBLOCK
) {
1601 found
= xfs_iext_next_extent(ifp
, &icur
, &got
);
1608 * Clear the inode reflink flag if there are no shared extents.
1610 * The caller is responsible for joining the inode to the transaction passed in.
1611 * The inode will be joined to the transaction that is returned to the caller.
1614 xfs_reflink_clear_inode_flag(
1615 struct xfs_inode
*ip
,
1616 struct xfs_trans
**tpp
)
1621 ASSERT(xfs_is_reflink_inode(ip
));
1623 error
= xfs_reflink_inode_has_shared_extents(*tpp
, ip
, &needs_flag
);
1624 if (error
|| needs_flag
)
1628 * We didn't find any shared blocks so turn off the reflink flag.
1629 * First, get rid of any leftover CoW mappings.
1631 error
= xfs_reflink_cancel_cow_blocks(ip
, tpp
, 0, XFS_MAX_FILEOFF
,
1636 /* Clear the inode flag. */
1637 trace_xfs_reflink_unset_inode_flag(ip
);
1638 ip
->i_diflags2
&= ~XFS_DIFLAG2_REFLINK
;
1639 xfs_inode_clear_cowblocks_tag(ip
);
1640 xfs_trans_log_inode(*tpp
, ip
, XFS_ILOG_CORE
);
1646 * Clear the inode reflink flag if there are no shared extents and the size
1650 xfs_reflink_try_clear_inode_flag(
1651 struct xfs_inode
*ip
)
1653 struct xfs_mount
*mp
= ip
->i_mount
;
1654 struct xfs_trans
*tp
;
1657 /* Start a rolling transaction to remove the mappings */
1658 error
= xfs_trans_alloc(mp
, &M_RES(mp
)->tr_write
, 0, 0, 0, &tp
);
1662 xfs_ilock(ip
, XFS_ILOCK_EXCL
);
1663 xfs_trans_ijoin(tp
, ip
, 0);
1665 error
= xfs_reflink_clear_inode_flag(ip
, &tp
);
1669 error
= xfs_trans_commit(tp
);
1673 xfs_iunlock(ip
, XFS_ILOCK_EXCL
);
1676 xfs_trans_cancel(tp
);
1678 xfs_iunlock(ip
, XFS_ILOCK_EXCL
);
1683 * Pre-COW all shared blocks within a given byte range of a file and turn off
1684 * the reflink flag if we unshare all of the file's blocks.
1687 xfs_reflink_unshare(
1688 struct xfs_inode
*ip
,
1692 struct inode
*inode
= VFS_I(ip
);
1695 if (!xfs_is_reflink_inode(ip
))
1698 trace_xfs_reflink_unshare(ip
, offset
, len
);
1700 inode_dio_wait(inode
);
1703 error
= dax_file_unshare(inode
, offset
, len
,
1704 &xfs_dax_write_iomap_ops
);
1706 error
= iomap_file_unshare(inode
, offset
, len
,
1707 &xfs_buffered_write_iomap_ops
);
1711 error
= filemap_write_and_wait_range(inode
->i_mapping
, offset
,
1716 /* Turn off the reflink flag if possible. */
1717 error
= xfs_reflink_try_clear_inode_flag(ip
);
1723 trace_xfs_reflink_unshare_error(ip
, error
, _RET_IP_
);