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_da_format.h"
15 #include "xfs_da_btree.h"
16 #include "xfs_inode.h"
17 #include "xfs_trans.h"
18 #include "xfs_inode_item.h"
20 #include "xfs_bmap_util.h"
21 #include "xfs_error.h"
23 #include "xfs_dir2_priv.h"
24 #include "xfs_ioctl.h"
25 #include "xfs_trace.h"
27 #include "xfs_icache.h"
29 #include "xfs_btree.h"
30 #include "xfs_refcount_btree.h"
31 #include "xfs_refcount.h"
32 #include "xfs_bmap_btree.h"
33 #include "xfs_trans_space.h"
35 #include "xfs_alloc.h"
36 #include "xfs_quota_defs.h"
37 #include "xfs_quota.h"
38 #include "xfs_reflink.h"
39 #include "xfs_iomap.h"
40 #include "xfs_rmap_btree.h"
42 #include "xfs_ag_resv.h"
45 * Copy on Write of Shared Blocks
47 * XFS must preserve "the usual" file semantics even when two files share
48 * the same physical blocks. This means that a write to one file must not
49 * alter the blocks in a different file; the way that we'll do that is
50 * through the use of a copy-on-write mechanism. At a high level, that
51 * means that when we want to write to a shared block, we allocate a new
52 * block, write the data to the new block, and if that succeeds we map the
53 * new block into the file.
55 * XFS provides a "delayed allocation" mechanism that defers the allocation
56 * of disk blocks to dirty-but-not-yet-mapped file blocks as long as
57 * possible. This reduces fragmentation by enabling the filesystem to ask
58 * for bigger chunks less often, which is exactly what we want for CoW.
60 * The delalloc mechanism begins when the kernel wants to make a block
61 * writable (write_begin or page_mkwrite). If the offset is not mapped, we
62 * create a delalloc mapping, which is a regular in-core extent, but without
63 * a real startblock. (For delalloc mappings, the startblock encodes both
64 * a flag that this is a delalloc mapping, and a worst-case estimate of how
65 * many blocks might be required to put the mapping into the BMBT.) delalloc
66 * mappings are a reservation against the free space in the filesystem;
67 * adjacent mappings can also be combined into fewer larger mappings.
69 * As an optimization, the CoW extent size hint (cowextsz) creates
70 * outsized aligned delalloc reservations in the hope of landing out of
71 * order nearby CoW writes in a single extent on disk, thereby reducing
72 * fragmentation and improving future performance.
74 * D: --RRRRRRSSSRRRRRRRR--- (data fork)
75 * C: ------DDDDDDD--------- (CoW fork)
77 * When dirty pages are being written out (typically in writepage), the
78 * delalloc reservations are converted into unwritten mappings by
79 * allocating blocks and replacing the delalloc mapping with real ones.
80 * A delalloc mapping can be replaced by several unwritten ones if the
81 * free space is fragmented.
83 * D: --RRRRRRSSSRRRRRRRR---
84 * C: ------UUUUUUU---------
86 * We want to adapt the delalloc mechanism for copy-on-write, since the
87 * write paths are similar. The first two steps (creating the reservation
88 * and allocating the blocks) are exactly the same as delalloc except that
89 * the mappings must be stored in a separate CoW fork because we do not want
90 * to disturb the mapping in the data fork until we're sure that the write
91 * succeeded. IO completion in this case is the process of removing the old
92 * mapping from the data fork and moving the new mapping from the CoW fork to
93 * the data fork. This will be discussed shortly.
95 * For now, unaligned directio writes will be bounced back to the page cache.
96 * Block-aligned directio writes will use the same mechanism as buffered
99 * Just prior to submitting the actual disk write requests, we convert
100 * the extents representing the range of the file actually being written
101 * (as opposed to extra pieces created for the cowextsize hint) to real
102 * extents. This will become important in the next step:
104 * D: --RRRRRRSSSRRRRRRRR---
105 * C: ------UUrrUUU---------
107 * CoW remapping must be done after the data block write completes,
108 * because we don't want to destroy the old data fork map until we're sure
109 * the new block has been written. Since the new mappings are kept in a
110 * separate fork, we can simply iterate these mappings to find the ones
111 * that cover the file blocks that we just CoW'd. For each extent, simply
112 * unmap the corresponding range in the data fork, map the new range into
113 * the data fork, and remove the extent from the CoW fork. Because of
114 * the presence of the cowextsize hint, however, we must be careful
115 * only to remap the blocks that we've actually written out -- we must
116 * never remap delalloc reservations nor CoW staging blocks that have
117 * yet to be written. This corresponds exactly to the real extents in
120 * D: --RRRRRRrrSRRRRRRRR---
121 * C: ------UU--UUU---------
123 * Since the remapping operation can be applied to an arbitrary file
124 * range, we record the need for the remap step as a flag in the ioend
125 * instead of declaring a new IO type. This is required for direct io
126 * because we only have ioend for the whole dio, and we have to be able to
127 * remember the presence of unwritten blocks and CoW blocks with a single
128 * ioend structure. Better yet, the more ground we can cover with one
133 * Given an AG extent, find the lowest-numbered run of shared blocks
134 * within that range and return the range in fbno/flen. If
135 * find_end_of_shared is true, return the longest contiguous extent of
136 * shared blocks. If there are no shared extents, fbno and flen will
137 * be set to NULLAGBLOCK and 0, respectively.
140 xfs_reflink_find_shared(
141 struct xfs_mount *mp,
142 struct xfs_trans *tp,
148 bool find_end_of_shared)
150 struct xfs_buf *agbp;
151 struct xfs_btree_cur *cur;
154 error = xfs_alloc_read_agf(mp, tp, agno, 0, &agbp);
160 cur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno);
162 error = xfs_refcount_find_shared(cur, agbno, aglen, fbno, flen,
165 xfs_btree_del_cursor(cur, error);
167 xfs_trans_brelse(tp, agbp);
172 * Trim the mapping to the next block where there's a change in the
173 * shared/unshared status. More specifically, this means that we
174 * find the lowest-numbered extent of shared blocks that coincides with
175 * the given block mapping. If the shared extent overlaps the start of
176 * the mapping, trim the mapping to the end of the shared extent. If
177 * the shared region intersects the mapping, trim the mapping to the
178 * start of the shared extent. If there are no shared regions that
179 * overlap, just return the original extent.
182 xfs_reflink_trim_around_shared(
183 struct xfs_inode *ip,
184 struct xfs_bmbt_irec *irec,
195 /* Holes, unwritten, and delalloc extents cannot be shared */
196 if (!xfs_is_reflink_inode(ip) || !xfs_bmap_is_real_extent(irec)) {
201 trace_xfs_reflink_trim_around_shared(ip, irec);
203 agno = XFS_FSB_TO_AGNO(ip->i_mount, irec->br_startblock);
204 agbno = XFS_FSB_TO_AGBNO(ip->i_mount, irec->br_startblock);
205 aglen = irec->br_blockcount;
207 error = xfs_reflink_find_shared(ip->i_mount, NULL, agno, agbno,
208 aglen, &fbno, &flen, true);
212 *shared = *trimmed = false;
213 if (fbno == NULLAGBLOCK) {
214 /* No shared blocks at all. */
216 } else if (fbno == agbno) {
218 * The start of this extent is shared. Truncate the
219 * mapping at the end of the shared region so that a
220 * subsequent iteration starts at the start of the
223 irec->br_blockcount = flen;
230 * There's a shared extent midway through this extent.
231 * Truncate the mapping at the start of the shared
232 * extent so that a subsequent iteration starts at the
233 * start of the shared region.
235 irec->br_blockcount = fbno - agbno;
242 * Trim the passed in imap to the next shared/unshared extent boundary, and
243 * if imap->br_startoff points to a shared extent reserve space for it in the
246 * Note that imap will always contain the block numbers for the existing blocks
247 * in the data fork, as the upper layers need them for read-modify-write
251 xfs_reflink_reserve_cow(
252 struct xfs_inode *ip,
253 struct xfs_bmbt_irec *imap)
255 struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
256 struct xfs_bmbt_irec got;
258 bool eof = false, trimmed;
259 struct xfs_iext_cursor icur;
263 * Search the COW fork extent list first. This serves two purposes:
264 * first this implement the speculative preallocation using cowextisze,
265 * so that we also unshared block adjacent to shared blocks instead
266 * of just the shared blocks themselves. Second the lookup in the
267 * extent list is generally faster than going out to the shared extent
271 if (!xfs_iext_lookup_extent(ip, ifp, imap->br_startoff, &icur, &got))
273 if (!eof && got.br_startoff <= imap->br_startoff) {
274 trace_xfs_reflink_cow_found(ip, imap);
275 xfs_trim_extent(imap, got.br_startoff, got.br_blockcount);
279 /* Trim the mapping to the nearest shared extent boundary. */
280 error = xfs_reflink_trim_around_shared(ip, imap, &shared, &trimmed);
284 /* Not shared? Just report the (potentially capped) extent. */
289 * Fork all the shared blocks from our write offset until the end of
292 error = xfs_qm_dqattach_locked(ip, false);
296 error = xfs_bmapi_reserve_delalloc(ip, XFS_COW_FORK, imap->br_startoff,
297 imap->br_blockcount, 0, &got, &icur, eof);
298 if (error == -ENOSPC || error == -EDQUOT)
299 trace_xfs_reflink_cow_enospc(ip, imap);
303 trace_xfs_reflink_cow_alloc(ip, &got);
307 /* Convert part of an unwritten CoW extent to a real one. */
309 xfs_reflink_convert_cow_extent(
310 struct xfs_inode *ip,
311 struct xfs_bmbt_irec *imap,
312 xfs_fileoff_t offset_fsb,
313 xfs_filblks_t count_fsb)
317 if (imap->br_state == XFS_EXT_NORM)
320 xfs_trim_extent(imap, offset_fsb, count_fsb);
321 trace_xfs_reflink_convert_cow(ip, imap);
322 if (imap->br_blockcount == 0)
324 return xfs_bmapi_write(NULL, ip, imap->br_startoff, imap->br_blockcount,
325 XFS_BMAPI_COWFORK | XFS_BMAPI_CONVERT, 0, imap,
329 /* Convert all of the unwritten CoW extents in a file's range to real ones. */
331 xfs_reflink_convert_cow(
332 struct xfs_inode *ip,
336 struct xfs_mount *mp = ip->i_mount;
337 xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset);
338 xfs_fileoff_t end_fsb = XFS_B_TO_FSB(mp, offset + count);
339 xfs_filblks_t count_fsb = end_fsb - offset_fsb;
340 struct xfs_bmbt_irec imap;
341 int nimaps = 1, error = 0;
345 xfs_ilock(ip, XFS_ILOCK_EXCL);
346 error = xfs_bmapi_write(NULL, ip, offset_fsb, count_fsb,
347 XFS_BMAPI_COWFORK | XFS_BMAPI_CONVERT |
348 XFS_BMAPI_CONVERT_ONLY, 0, &imap, &nimaps);
349 xfs_iunlock(ip, XFS_ILOCK_EXCL);
354 * Find the extent that maps the given range in the COW fork. Even if the extent
355 * is not shared we might have a preallocation for it in the COW fork. If so we
356 * use it that rather than trigger a new allocation.
359 xfs_find_trim_cow_extent(
360 struct xfs_inode *ip,
361 struct xfs_bmbt_irec *imap,
365 xfs_fileoff_t offset_fsb = imap->br_startoff;
366 xfs_filblks_t count_fsb = imap->br_blockcount;
367 struct xfs_iext_cursor icur;
368 struct xfs_bmbt_irec got;
374 * If we don't find an overlapping extent, trim the range we need to
375 * allocate to fit the hole we found.
377 if (!xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &got) ||
378 got.br_startoff > offset_fsb)
379 return xfs_reflink_trim_around_shared(ip, imap, shared, &trimmed);
382 if (isnullstartblock(got.br_startblock)) {
383 xfs_trim_extent(imap, got.br_startoff, got.br_blockcount);
387 /* real extent found - no need to allocate */
388 xfs_trim_extent(&got, offset_fsb, count_fsb);
394 /* Allocate all CoW reservations covering a range of blocks in a file. */
396 xfs_reflink_allocate_cow(
397 struct xfs_inode *ip,
398 struct xfs_bmbt_irec *imap,
402 struct xfs_mount *mp = ip->i_mount;
403 xfs_fileoff_t offset_fsb = imap->br_startoff;
404 xfs_filblks_t count_fsb = imap->br_blockcount;
405 struct xfs_trans *tp;
406 int nimaps, error = 0;
408 xfs_filblks_t resaligned;
409 xfs_extlen_t resblks = 0;
411 ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
412 ASSERT(xfs_is_reflink_inode(ip));
414 error = xfs_find_trim_cow_extent(ip, imap, shared, &found);
415 if (error || !*shared)
420 resaligned = xfs_aligned_fsb_count(imap->br_startoff,
421 imap->br_blockcount, xfs_get_cowextsz_hint(ip));
422 resblks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
424 xfs_iunlock(ip, *lockmode);
425 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0, 0, &tp);
426 *lockmode = XFS_ILOCK_EXCL;
427 xfs_ilock(ip, *lockmode);
432 error = xfs_qm_dqattach_locked(ip, false);
434 goto out_trans_cancel;
437 * Check for an overlapping extent again now that we dropped the ilock.
439 error = xfs_find_trim_cow_extent(ip, imap, shared, &found);
440 if (error || !*shared)
441 goto out_trans_cancel;
443 xfs_trans_cancel(tp);
447 error = xfs_trans_reserve_quota_nblks(tp, ip, resblks, 0,
448 XFS_QMOPT_RES_REGBLKS);
450 goto out_trans_cancel;
452 xfs_trans_ijoin(tp, ip, 0);
454 /* Allocate the entire reservation as unwritten blocks. */
456 error = xfs_bmapi_write(tp, ip, imap->br_startoff, imap->br_blockcount,
457 XFS_BMAPI_COWFORK | XFS_BMAPI_PREALLOC,
458 resblks, imap, &nimaps);
462 xfs_inode_set_cowblocks_tag(ip);
463 error = xfs_trans_commit(tp);
468 * Allocation succeeded but the requested range was not even partially
469 * satisfied? Bail out!
474 return xfs_reflink_convert_cow_extent(ip, imap, offset_fsb, count_fsb);
477 xfs_trans_unreserve_quota_nblks(tp, ip, (long)resblks, 0,
478 XFS_QMOPT_RES_REGBLKS);
480 xfs_trans_cancel(tp);
485 * Cancel CoW reservations for some block range of an inode.
487 * If cancel_real is true this function cancels all COW fork extents for the
488 * inode; if cancel_real is false, real extents are not cleared.
490 * Caller must have already joined the inode to the current transaction. The
491 * inode will be joined to the transaction returned to the caller.
494 xfs_reflink_cancel_cow_blocks(
495 struct xfs_inode *ip,
496 struct xfs_trans **tpp,
497 xfs_fileoff_t offset_fsb,
498 xfs_fileoff_t end_fsb,
501 struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
502 struct xfs_bmbt_irec got, del;
503 struct xfs_iext_cursor icur;
506 if (!xfs_inode_has_cow_data(ip))
508 if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &icur, &got))
511 /* Walk backwards until we're out of the I/O range... */
512 while (got.br_startoff + got.br_blockcount > offset_fsb) {
514 xfs_trim_extent(&del, offset_fsb, end_fsb - offset_fsb);
516 /* Extent delete may have bumped ext forward */
517 if (!del.br_blockcount) {
518 xfs_iext_prev(ifp, &icur);
522 trace_xfs_reflink_cancel_cow(ip, &del);
524 if (isnullstartblock(del.br_startblock)) {
525 error = xfs_bmap_del_extent_delay(ip, XFS_COW_FORK,
529 } else if (del.br_state == XFS_EXT_UNWRITTEN || cancel_real) {
530 ASSERT((*tpp)->t_firstblock == NULLFSBLOCK);
532 /* Free the CoW orphan record. */
533 error = xfs_refcount_free_cow_extent(*tpp,
534 del.br_startblock, del.br_blockcount);
538 xfs_bmap_add_free(*tpp, del.br_startblock,
539 del.br_blockcount, NULL);
541 /* Roll the transaction */
542 error = xfs_defer_finish(tpp);
546 /* Remove the mapping from the CoW fork. */
547 xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
549 /* Remove the quota reservation */
550 error = xfs_trans_reserve_quota_nblks(NULL, ip,
551 -(long)del.br_blockcount, 0,
552 XFS_QMOPT_RES_REGBLKS);
556 /* Didn't do anything, push cursor back. */
557 xfs_iext_prev(ifp, &icur);
560 if (!xfs_iext_get_extent(ifp, &icur, &got))
564 /* clear tag if cow fork is emptied */
566 xfs_inode_clear_cowblocks_tag(ip);
571 * Cancel CoW reservations for some byte range of an inode.
573 * If cancel_real is true this function cancels all COW fork extents for the
574 * inode; if cancel_real is false, real extents are not cleared.
577 xfs_reflink_cancel_cow_range(
578 struct xfs_inode *ip,
583 struct xfs_trans *tp;
584 xfs_fileoff_t offset_fsb;
585 xfs_fileoff_t end_fsb;
588 trace_xfs_reflink_cancel_cow_range(ip, offset, count);
589 ASSERT(xfs_is_reflink_inode(ip));
591 offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
592 if (count == NULLFILEOFF)
593 end_fsb = NULLFILEOFF;
595 end_fsb = XFS_B_TO_FSB(ip->i_mount, offset + count);
597 /* Start a rolling transaction to remove the mappings */
598 error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_write,
599 0, 0, XFS_TRANS_NOFS, &tp);
603 xfs_ilock(ip, XFS_ILOCK_EXCL);
604 xfs_trans_ijoin(tp, ip, 0);
606 /* Scrape out the old CoW reservations */
607 error = xfs_reflink_cancel_cow_blocks(ip, &tp, offset_fsb, end_fsb,
612 error = xfs_trans_commit(tp);
614 xfs_iunlock(ip, XFS_ILOCK_EXCL);
618 xfs_trans_cancel(tp);
619 xfs_iunlock(ip, XFS_ILOCK_EXCL);
621 trace_xfs_reflink_cancel_cow_range_error(ip, error, _RET_IP_);
626 * Remap parts of a file's data fork after a successful CoW.
630 struct xfs_inode *ip,
634 struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
635 struct xfs_bmbt_irec got, del;
636 struct xfs_trans *tp;
637 xfs_fileoff_t offset_fsb;
638 xfs_fileoff_t end_fsb;
640 unsigned int resblks;
642 struct xfs_iext_cursor icur;
644 trace_xfs_reflink_end_cow(ip, offset, count);
646 /* No COW extents? That's easy! */
647 if (ifp->if_bytes == 0)
650 offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
651 end_fsb = XFS_B_TO_FSB(ip->i_mount, offset + count);
654 * Start a rolling transaction to switch the mappings. We're
655 * unlikely ever to have to remap 16T worth of single-block
656 * extents, so just cap the worst case extent count to 2^32-1.
657 * Stick a warning in just in case, and avoid 64-bit division.
659 BUILD_BUG_ON(MAX_RW_COUNT > UINT_MAX);
660 if (end_fsb - offset_fsb > UINT_MAX) {
661 error = -EFSCORRUPTED;
662 xfs_force_shutdown(ip->i_mount, SHUTDOWN_CORRUPT_INCORE);
666 resblks = XFS_NEXTENTADD_SPACE_RES(ip->i_mount,
667 (unsigned int)(end_fsb - offset_fsb),
669 error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_write,
670 resblks, 0, XFS_TRANS_RESERVE | XFS_TRANS_NOFS, &tp);
674 xfs_ilock(ip, XFS_ILOCK_EXCL);
675 xfs_trans_ijoin(tp, ip, 0);
678 * In case of racing, overlapping AIO writes no COW extents might be
679 * left by the time I/O completes for the loser of the race. In that
682 if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &icur, &got))
685 /* Walk backwards until we're out of the I/O range... */
686 while (got.br_startoff + got.br_blockcount > offset_fsb) {
688 xfs_trim_extent(&del, offset_fsb, end_fsb - offset_fsb);
690 /* Extent delete may have bumped ext forward */
691 if (!del.br_blockcount)
695 * Only remap real extent that contain data. With AIO
696 * speculatively preallocations can leak into the range we
697 * are called upon, and we need to skip them.
699 if (!xfs_bmap_is_real_extent(&got))
702 /* Unmap the old blocks in the data fork. */
703 ASSERT(tp->t_firstblock == NULLFSBLOCK);
704 rlen = del.br_blockcount;
705 error = __xfs_bunmapi(tp, ip, del.br_startoff, &rlen, 0, 1);
709 /* Trim the extent to whatever got unmapped. */
711 xfs_trim_extent(&del, del.br_startoff + rlen,
712 del.br_blockcount - rlen);
714 trace_xfs_reflink_cow_remap(ip, &del);
716 /* Free the CoW orphan record. */
717 error = xfs_refcount_free_cow_extent(tp, del.br_startblock,
722 /* Map the new blocks into the data fork. */
723 error = xfs_bmap_map_extent(tp, ip, &del);
727 /* Charge this new data fork mapping to the on-disk quota. */
728 xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_DELBCOUNT,
729 (long)del.br_blockcount);
731 /* Remove the mapping from the CoW fork. */
732 xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
734 error = xfs_defer_finish(&tp);
737 if (!xfs_iext_get_extent(ifp, &icur, &got))
741 if (!xfs_iext_prev_extent(ifp, &icur, &got))
745 error = xfs_trans_commit(tp);
746 xfs_iunlock(ip, XFS_ILOCK_EXCL);
752 xfs_trans_cancel(tp);
753 xfs_iunlock(ip, XFS_ILOCK_EXCL);
755 trace_xfs_reflink_end_cow_error(ip, error, _RET_IP_);
760 * Free leftover CoW reservations that didn't get cleaned out.
763 xfs_reflink_recover_cow(
764 struct xfs_mount *mp)
769 if (!xfs_sb_version_hasreflink(&mp->m_sb))
772 for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
773 error = xfs_refcount_recover_cow_leftovers(mp, agno);
782 * Reflinking (Block) Ranges of Two Files Together
784 * First, ensure that the reflink flag is set on both inodes. The flag is an
785 * optimization to avoid unnecessary refcount btree lookups in the write path.
787 * Now we can iteratively remap the range of extents (and holes) in src to the
788 * corresponding ranges in dest. Let drange and srange denote the ranges of
789 * logical blocks in dest and src touched by the reflink operation.
791 * While the length of drange is greater than zero,
792 * - Read src's bmbt at the start of srange ("imap")
793 * - If imap doesn't exist, make imap appear to start at the end of srange
795 * - If imap starts before srange, advance imap to start at srange.
796 * - If imap goes beyond srange, truncate imap to end at the end of srange.
797 * - Punch (imap start - srange start + imap len) blocks from dest at
798 * offset (drange start).
799 * - If imap points to a real range of pblks,
800 * > Increase the refcount of the imap's pblks
801 * > Map imap's pblks into dest at the offset
802 * (drange start + imap start - srange start)
803 * - Advance drange and srange by (imap start - srange start + imap len)
805 * Finally, if the reflink made dest longer, update both the in-core and
806 * on-disk file sizes.
808 * ASCII Art Demonstration:
810 * Let's say we want to reflink this source file:
812 * ----SSSSSSS-SSSSS----SSSSSS (src file)
813 * <-------------------->
815 * into this destination file:
817 * --DDDDDDDDDDDDDDDDDDD--DDD (dest file)
818 * <-------------------->
819 * '-' means a hole, and 'S' and 'D' are written blocks in the src and dest.
820 * Observe that the range has different logical offsets in either file.
822 * Consider that the first extent in the source file doesn't line up with our
823 * reflink range. Unmapping and remapping are separate operations, so we can
824 * unmap more blocks from the destination file than we remap.
826 * ----SSSSSSS-SSSSS----SSSSSS
828 * --DDDDD---------DDDDD--DDD
831 * Now remap the source extent into the destination file:
833 * ----SSSSSSS-SSSSS----SSSSSS
835 * --DDDDD--SSSSSSSDDDDD--DDD
838 * Do likewise with the second hole and extent in our range. Holes in the
839 * unmap range don't affect our operation.
841 * ----SSSSSSS-SSSSS----SSSSSS
843 * --DDDDD--SSSSSSS-SSSSS-DDD
846 * Finally, unmap and remap part of the third extent. This will increase the
847 * size of the destination file.
849 * ----SSSSSSS-SSSSS----SSSSSS
851 * --DDDDD--SSSSSSS-SSSSS----SSS
854 * Once we update the destination file's i_size, we're done.
858 * Ensure the reflink bit is set in both inodes.
861 xfs_reflink_set_inode_flag(
862 struct xfs_inode *src,
863 struct xfs_inode *dest)
865 struct xfs_mount *mp = src->i_mount;
867 struct xfs_trans *tp;
869 if (xfs_is_reflink_inode(src) && xfs_is_reflink_inode(dest))
872 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
876 /* Lock both files against IO */
877 if (src->i_ino == dest->i_ino)
878 xfs_ilock(src, XFS_ILOCK_EXCL);
880 xfs_lock_two_inodes(src, XFS_ILOCK_EXCL, dest, XFS_ILOCK_EXCL);
882 if (!xfs_is_reflink_inode(src)) {
883 trace_xfs_reflink_set_inode_flag(src);
884 xfs_trans_ijoin(tp, src, XFS_ILOCK_EXCL);
885 src->i_d.di_flags2 |= XFS_DIFLAG2_REFLINK;
886 xfs_trans_log_inode(tp, src, XFS_ILOG_CORE);
887 xfs_ifork_init_cow(src);
889 xfs_iunlock(src, XFS_ILOCK_EXCL);
891 if (src->i_ino == dest->i_ino)
894 if (!xfs_is_reflink_inode(dest)) {
895 trace_xfs_reflink_set_inode_flag(dest);
896 xfs_trans_ijoin(tp, dest, XFS_ILOCK_EXCL);
897 dest->i_d.di_flags2 |= XFS_DIFLAG2_REFLINK;
898 xfs_trans_log_inode(tp, dest, XFS_ILOG_CORE);
899 xfs_ifork_init_cow(dest);
901 xfs_iunlock(dest, XFS_ILOCK_EXCL);
904 error = xfs_trans_commit(tp);
910 trace_xfs_reflink_set_inode_flag_error(dest, error, _RET_IP_);
915 * Update destination inode size & cowextsize hint, if necessary.
918 xfs_reflink_update_dest(
919 struct xfs_inode *dest,
921 xfs_extlen_t cowextsize,
924 struct xfs_mount *mp = dest->i_mount;
925 struct xfs_trans *tp;
928 if (is_dedupe && newlen <= i_size_read(VFS_I(dest)) && cowextsize == 0)
931 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
935 xfs_ilock(dest, XFS_ILOCK_EXCL);
936 xfs_trans_ijoin(tp, dest, XFS_ILOCK_EXCL);
938 if (newlen > i_size_read(VFS_I(dest))) {
939 trace_xfs_reflink_update_inode_size(dest, newlen);
940 i_size_write(VFS_I(dest), newlen);
941 dest->i_d.di_size = newlen;
945 dest->i_d.di_cowextsize = cowextsize;
946 dest->i_d.di_flags2 |= XFS_DIFLAG2_COWEXTSIZE;
950 xfs_trans_ichgtime(tp, dest,
951 XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
953 xfs_trans_log_inode(tp, dest, XFS_ILOG_CORE);
955 error = xfs_trans_commit(tp);
961 trace_xfs_reflink_update_inode_size_error(dest, error, _RET_IP_);
966 * Do we have enough reserve in this AG to handle a reflink? The refcount
967 * btree already reserved all the space it needs, but the rmap btree can grow
968 * infinitely, so we won't allow more reflinks when the AG is down to the
972 xfs_reflink_ag_has_free_space(
973 struct xfs_mount *mp,
976 struct xfs_perag *pag;
979 if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
982 pag = xfs_perag_get(mp, agno);
983 if (xfs_ag_resv_critical(pag, XFS_AG_RESV_RMAPBT) ||
984 xfs_ag_resv_critical(pag, XFS_AG_RESV_METADATA))
991 * Unmap a range of blocks from a file, then map other blocks into the hole.
992 * The range to unmap is (destoff : destoff + srcioff + irec->br_blockcount).
993 * The extent irec is mapped into dest at irec->br_startoff.
996 xfs_reflink_remap_extent(
997 struct xfs_inode *ip,
998 struct xfs_bmbt_irec *irec,
999 xfs_fileoff_t destoff,
1000 xfs_off_t new_isize)
1002 struct xfs_mount *mp = ip->i_mount;
1003 bool real_extent = xfs_bmap_is_real_extent(irec);
1004 struct xfs_trans *tp;
1005 unsigned int resblks;
1006 struct xfs_bmbt_irec uirec;
1008 xfs_filblks_t unmap_len;
1012 unmap_len = irec->br_startoff + irec->br_blockcount - destoff;
1013 trace_xfs_reflink_punch_range(ip, destoff, unmap_len);
1015 /* No reflinking if we're low on space */
1017 error = xfs_reflink_ag_has_free_space(mp,
1018 XFS_FSB_TO_AGNO(mp, irec->br_startblock));
1023 /* Start a rolling transaction to switch the mappings */
1024 resblks = XFS_EXTENTADD_SPACE_RES(ip->i_mount, XFS_DATA_FORK);
1025 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0, 0, &tp);
1029 xfs_ilock(ip, XFS_ILOCK_EXCL);
1030 xfs_trans_ijoin(tp, ip, 0);
1032 /* If we're not just clearing space, then do we have enough quota? */
1034 error = xfs_trans_reserve_quota_nblks(tp, ip,
1035 irec->br_blockcount, 0, XFS_QMOPT_RES_REGBLKS);
1040 trace_xfs_reflink_remap(ip, irec->br_startoff,
1041 irec->br_blockcount, irec->br_startblock);
1043 /* Unmap the old blocks in the data fork. */
1046 ASSERT(tp->t_firstblock == NULLFSBLOCK);
1047 error = __xfs_bunmapi(tp, ip, destoff, &rlen, 0, 1);
1052 * Trim the extent to whatever got unmapped.
1053 * Remember, bunmapi works backwards.
1055 uirec.br_startblock = irec->br_startblock + rlen;
1056 uirec.br_startoff = irec->br_startoff + rlen;
1057 uirec.br_blockcount = unmap_len - rlen;
1060 /* If this isn't a real mapping, we're done. */
1061 if (!real_extent || uirec.br_blockcount == 0)
1064 trace_xfs_reflink_remap(ip, uirec.br_startoff,
1065 uirec.br_blockcount, uirec.br_startblock);
1067 /* Update the refcount tree */
1068 error = xfs_refcount_increase_extent(tp, &uirec);
1072 /* Map the new blocks into the data fork. */
1073 error = xfs_bmap_map_extent(tp, ip, &uirec);
1077 /* Update quota accounting. */
1078 xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT,
1079 uirec.br_blockcount);
1081 /* Update dest isize if needed. */
1082 newlen = XFS_FSB_TO_B(mp,
1083 uirec.br_startoff + uirec.br_blockcount);
1084 newlen = min_t(xfs_off_t, newlen, new_isize);
1085 if (newlen > i_size_read(VFS_I(ip))) {
1086 trace_xfs_reflink_update_inode_size(ip, newlen);
1087 i_size_write(VFS_I(ip), newlen);
1088 ip->i_d.di_size = newlen;
1089 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
1093 /* Process all the deferred stuff. */
1094 error = xfs_defer_finish(&tp);
1099 error = xfs_trans_commit(tp);
1100 xfs_iunlock(ip, XFS_ILOCK_EXCL);
1106 xfs_trans_cancel(tp);
1107 xfs_iunlock(ip, XFS_ILOCK_EXCL);
1109 trace_xfs_reflink_remap_extent_error(ip, error, _RET_IP_);
1114 * Iteratively remap one file's extents (and holes) to another's.
1117 xfs_reflink_remap_blocks(
1118 struct xfs_inode *src,
1119 xfs_fileoff_t srcoff,
1120 struct xfs_inode *dest,
1121 xfs_fileoff_t destoff,
1123 xfs_off_t new_isize)
1125 struct xfs_bmbt_irec imap;
1128 xfs_filblks_t range_len;
1130 /* drange = (destoff, destoff + len); srange = (srcoff, srcoff + len) */
1134 trace_xfs_reflink_remap_blocks_loop(src, srcoff, len,
1137 /* Read extent from the source file */
1139 lock_mode = xfs_ilock_data_map_shared(src);
1140 error = xfs_bmapi_read(src, srcoff, len, &imap, &nimaps, 0);
1141 xfs_iunlock(src, lock_mode);
1144 ASSERT(nimaps == 1);
1146 trace_xfs_reflink_remap_imap(src, srcoff, len, XFS_IO_OVERWRITE,
1149 /* Translate imap into the destination file. */
1150 range_len = imap.br_startoff + imap.br_blockcount - srcoff;
1151 imap.br_startoff += destoff - srcoff;
1153 /* Clear dest from destoff to the end of imap and map it in. */
1154 error = xfs_reflink_remap_extent(dest, &imap, destoff,
1159 if (fatal_signal_pending(current)) {
1164 /* Advance drange/srange */
1165 srcoff += range_len;
1166 destoff += range_len;
1173 trace_xfs_reflink_remap_blocks_error(dest, error, _RET_IP_);
1178 * Grab the exclusive iolock for a data copy from src to dest, making
1179 * sure to abide vfs locking order (lowest pointer value goes first) and
1180 * breaking the pnfs layout leases on dest before proceeding. The loop
1181 * is needed because we cannot call the blocking break_layout() with the
1182 * src iolock held, and therefore have to back out both locks.
1185 xfs_iolock_two_inodes_and_break_layout(
1193 inode_lock_shared(src);
1194 inode_lock_nested(dest, I_MUTEX_NONDIR2);
1200 error = break_layout(dest, false);
1201 if (error == -EWOULDBLOCK) {
1204 inode_unlock_shared(src);
1205 error = break_layout(dest, true);
1213 inode_unlock_shared(src);
1217 inode_lock_shared_nested(src, I_MUTEX_NONDIR2);
1221 /* Unlock both inodes after they've been prepped for a range clone. */
1223 xfs_reflink_remap_unlock(
1224 struct file *file_in,
1225 struct file *file_out)
1227 struct inode *inode_in = file_inode(file_in);
1228 struct xfs_inode *src = XFS_I(inode_in);
1229 struct inode *inode_out = file_inode(file_out);
1230 struct xfs_inode *dest = XFS_I(inode_out);
1231 bool same_inode = (inode_in == inode_out);
1233 xfs_iunlock(dest, XFS_MMAPLOCK_EXCL);
1235 xfs_iunlock(src, XFS_MMAPLOCK_SHARED);
1236 inode_unlock(inode_out);
1238 inode_unlock_shared(inode_in);
1242 * If we're reflinking to a point past the destination file's EOF, we must
1243 * zero any speculative post-EOF preallocations that sit between the old EOF
1244 * and the destination file offset.
1247 xfs_reflink_zero_posteof(
1248 struct xfs_inode *ip,
1251 loff_t isize = i_size_read(VFS_I(ip));
1256 trace_xfs_zero_eof(ip, isize, pos - isize);
1257 return iomap_zero_range(VFS_I(ip), isize, pos - isize, NULL,
1262 * Prepare two files for range cloning. Upon a successful return both inodes
1263 * will have the iolock and mmaplock held, the page cache of the out file will
1264 * be truncated, and any leases on the out file will have been broken. This
1265 * function borrows heavily from xfs_file_aio_write_checks.
1267 * The VFS allows partial EOF blocks to "match" for dedupe even though it hasn't
1268 * checked that the bytes beyond EOF physically match. Hence we cannot use the
1269 * EOF block in the source dedupe range because it's not a complete block match,
1270 * hence can introduce a corruption into the file that has it's block replaced.
1272 * In similar fashion, the VFS file cloning also allows partial EOF blocks to be
1273 * "block aligned" for the purposes of cloning entire files. However, if the
1274 * source file range includes the EOF block and it lands within the existing EOF
1275 * of the destination file, then we can expose stale data from beyond the source
1276 * file EOF in the destination file.
1278 * XFS doesn't support partial block sharing, so in both cases we have check
1279 * these cases ourselves. For dedupe, we can simply round the length to dedupe
1280 * down to the previous whole block and ignore the partial EOF block. While this
1281 * means we can't dedupe the last block of a file, this is an acceptible
1282 * tradeoff for simplicity on implementation.
1284 * For cloning, we want to share the partial EOF block if it is also the new EOF
1285 * block of the destination file. If the partial EOF block lies inside the
1286 * existing destination EOF, then we have to abort the clone to avoid exposing
1287 * stale data in the destination file. Hence we reject these clone attempts with
1288 * -EINVAL in this case.
1291 xfs_reflink_remap_prep(
1292 struct file *file_in,
1294 struct file *file_out,
1299 struct inode *inode_in = file_inode(file_in);
1300 struct xfs_inode *src = XFS_I(inode_in);
1301 struct inode *inode_out = file_inode(file_out);
1302 struct xfs_inode *dest = XFS_I(inode_out);
1303 bool same_inode = (inode_in == inode_out);
1304 u64 blkmask = i_blocksize(inode_in) - 1;
1307 /* Lock both files against IO */
1308 ret = xfs_iolock_two_inodes_and_break_layout(inode_in, inode_out);
1312 xfs_ilock(src, XFS_MMAPLOCK_EXCL);
1314 xfs_lock_two_inodes(src, XFS_MMAPLOCK_SHARED, dest,
1317 /* Check file eligibility and prepare for block sharing. */
1319 /* Don't reflink realtime inodes */
1320 if (XFS_IS_REALTIME_INODE(src) || XFS_IS_REALTIME_INODE(dest))
1323 /* Don't share DAX file data for now. */
1324 if (IS_DAX(inode_in) || IS_DAX(inode_out))
1327 ret = vfs_clone_file_prep_inodes(inode_in, pos_in, inode_out, pos_out,
1333 * If the dedupe data matches, chop off the partial EOF block
1334 * from the source file so we don't try to dedupe the partial
1339 } else if (*len & blkmask) {
1341 * The user is attempting to share a partial EOF block,
1342 * if it's inside the destination EOF then reject it.
1344 if (pos_out + *len < i_size_read(inode_out)) {
1350 /* Attach dquots to dest inode before changing block map */
1351 ret = xfs_qm_dqattach(dest);
1356 * Zero existing post-eof speculative preallocations in the destination
1359 ret = xfs_reflink_zero_posteof(dest, pos_out);
1363 /* Set flags and remap blocks. */
1364 ret = xfs_reflink_set_inode_flag(src, dest);
1368 /* Zap any page cache for the destination file's range. */
1369 truncate_inode_pages_range(&inode_out->i_data, pos_out,
1370 PAGE_ALIGN(pos_out + *len) - 1);
1372 /* If we're altering the file contents... */
1375 * ...update the timestamps (which will grab the ilock again
1376 * from xfs_fs_dirty_inode, so we have to call it before we
1379 if (!(file_out->f_mode & FMODE_NOCMTIME)) {
1380 ret = file_update_time(file_out);
1386 * ...clear the security bits if the process is not being run
1387 * by root. This keeps people from modifying setuid and setgid
1390 ret = file_remove_privs(file_out);
1397 xfs_reflink_remap_unlock(file_in, file_out);
1402 * Link a range of blocks from one file to another.
1405 xfs_reflink_remap_range(
1406 struct file *file_in,
1408 struct file *file_out,
1413 struct inode *inode_in = file_inode(file_in);
1414 struct xfs_inode *src = XFS_I(inode_in);
1415 struct inode *inode_out = file_inode(file_out);
1416 struct xfs_inode *dest = XFS_I(inode_out);
1417 struct xfs_mount *mp = src->i_mount;
1418 xfs_fileoff_t sfsbno, dfsbno;
1419 xfs_filblks_t fsblen;
1420 xfs_extlen_t cowextsize;
1423 if (!xfs_sb_version_hasreflink(&mp->m_sb))
1426 if (XFS_FORCED_SHUTDOWN(mp))
1429 /* Prepare and then clone file data. */
1430 ret = xfs_reflink_remap_prep(file_in, pos_in, file_out, pos_out,
1435 trace_xfs_reflink_remap_range(src, pos_in, len, dest, pos_out);
1437 dfsbno = XFS_B_TO_FSBT(mp, pos_out);
1438 sfsbno = XFS_B_TO_FSBT(mp, pos_in);
1439 fsblen = XFS_B_TO_FSB(mp, len);
1440 ret = xfs_reflink_remap_blocks(src, sfsbno, dest, dfsbno, fsblen,
1446 * Carry the cowextsize hint from src to dest if we're sharing the
1447 * entire source file to the entire destination file, the source file
1448 * has a cowextsize hint, and the destination file does not.
1451 if (pos_in == 0 && len == i_size_read(inode_in) &&
1452 (src->i_d.di_flags2 & XFS_DIFLAG2_COWEXTSIZE) &&
1453 pos_out == 0 && len >= i_size_read(inode_out) &&
1454 !(dest->i_d.di_flags2 & XFS_DIFLAG2_COWEXTSIZE))
1455 cowextsize = src->i_d.di_cowextsize;
1457 ret = xfs_reflink_update_dest(dest, pos_out + len, cowextsize,
1461 xfs_reflink_remap_unlock(file_in, file_out);
1463 trace_xfs_reflink_remap_range_error(dest, ret, _RET_IP_);
1468 * The user wants to preemptively CoW all shared blocks in this file,
1469 * which enables us to turn off the reflink flag. Iterate all
1470 * extents which are not prealloc/delalloc to see which ranges are
1471 * mentioned in the refcount tree, then read those blocks into the
1472 * pagecache, dirty them, fsync them back out, and then we can update
1473 * the inode flag. What happens if we run out of memory? :)
1476 xfs_reflink_dirty_extents(
1477 struct xfs_inode *ip,
1482 struct xfs_mount *mp = ip->i_mount;
1483 xfs_agnumber_t agno;
1484 xfs_agblock_t agbno;
1490 struct xfs_bmbt_irec map[2];
1494 while (end - fbno > 0) {
1497 * Look for extents in the file. Skip holes, delalloc, or
1498 * unwritten extents; they can't be reflinked.
1500 error = xfs_bmapi_read(ip, fbno, end - fbno, map, &nmaps, 0);
1505 if (!xfs_bmap_is_real_extent(&map[0]))
1509 while (map[1].br_blockcount) {
1510 agno = XFS_FSB_TO_AGNO(mp, map[1].br_startblock);
1511 agbno = XFS_FSB_TO_AGBNO(mp, map[1].br_startblock);
1512 aglen = map[1].br_blockcount;
1514 error = xfs_reflink_find_shared(mp, NULL, agno, agbno,
1515 aglen, &rbno, &rlen, true);
1518 if (rbno == NULLAGBLOCK)
1521 /* Dirty the pages */
1522 xfs_iunlock(ip, XFS_ILOCK_EXCL);
1523 fpos = XFS_FSB_TO_B(mp, map[1].br_startoff +
1525 flen = XFS_FSB_TO_B(mp, rlen);
1526 if (fpos + flen > isize)
1527 flen = isize - fpos;
1528 error = iomap_file_dirty(VFS_I(ip), fpos, flen,
1530 xfs_ilock(ip, XFS_ILOCK_EXCL);
1534 map[1].br_blockcount -= (rbno - agbno + rlen);
1535 map[1].br_startoff += (rbno - agbno + rlen);
1536 map[1].br_startblock += (rbno - agbno + rlen);
1540 fbno = map[0].br_startoff + map[0].br_blockcount;
1546 /* Does this inode need the reflink flag? */
1548 xfs_reflink_inode_has_shared_extents(
1549 struct xfs_trans *tp,
1550 struct xfs_inode *ip,
1553 struct xfs_bmbt_irec got;
1554 struct xfs_mount *mp = ip->i_mount;
1555 struct xfs_ifork *ifp;
1556 xfs_agnumber_t agno;
1557 xfs_agblock_t agbno;
1561 struct xfs_iext_cursor icur;
1565 ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
1566 if (!(ifp->if_flags & XFS_IFEXTENTS)) {
1567 error = xfs_iread_extents(tp, ip, XFS_DATA_FORK);
1572 *has_shared = false;
1573 found = xfs_iext_lookup_extent(ip, ifp, 0, &icur, &got);
1575 if (isnullstartblock(got.br_startblock) ||
1576 got.br_state != XFS_EXT_NORM)
1578 agno = XFS_FSB_TO_AGNO(mp, got.br_startblock);
1579 agbno = XFS_FSB_TO_AGBNO(mp, got.br_startblock);
1580 aglen = got.br_blockcount;
1582 error = xfs_reflink_find_shared(mp, tp, agno, agbno, aglen,
1583 &rbno, &rlen, false);
1586 /* Is there still a shared block here? */
1587 if (rbno != NULLAGBLOCK) {
1592 found = xfs_iext_next_extent(ifp, &icur, &got);
1599 * Clear the inode reflink flag if there are no shared extents.
1601 * The caller is responsible for joining the inode to the transaction passed in.
1602 * The inode will be joined to the transaction that is returned to the caller.
1605 xfs_reflink_clear_inode_flag(
1606 struct xfs_inode *ip,
1607 struct xfs_trans **tpp)
1612 ASSERT(xfs_is_reflink_inode(ip));
1614 error = xfs_reflink_inode_has_shared_extents(*tpp, ip, &needs_flag);
1615 if (error || needs_flag)
1619 * We didn't find any shared blocks so turn off the reflink flag.
1620 * First, get rid of any leftover CoW mappings.
1622 error = xfs_reflink_cancel_cow_blocks(ip, tpp, 0, NULLFILEOFF, true);
1626 /* Clear the inode flag. */
1627 trace_xfs_reflink_unset_inode_flag(ip);
1628 ip->i_d.di_flags2 &= ~XFS_DIFLAG2_REFLINK;
1629 xfs_inode_clear_cowblocks_tag(ip);
1630 xfs_trans_log_inode(*tpp, ip, XFS_ILOG_CORE);
1636 * Clear the inode reflink flag if there are no shared extents and the size
1640 xfs_reflink_try_clear_inode_flag(
1641 struct xfs_inode *ip)
1643 struct xfs_mount *mp = ip->i_mount;
1644 struct xfs_trans *tp;
1647 /* Start a rolling transaction to remove the mappings */
1648 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0, 0, &tp);
1652 xfs_ilock(ip, XFS_ILOCK_EXCL);
1653 xfs_trans_ijoin(tp, ip, 0);
1655 error = xfs_reflink_clear_inode_flag(ip, &tp);
1659 error = xfs_trans_commit(tp);
1663 xfs_iunlock(ip, XFS_ILOCK_EXCL);
1666 xfs_trans_cancel(tp);
1668 xfs_iunlock(ip, XFS_ILOCK_EXCL);
1673 * Pre-COW all shared blocks within a given byte range of a file and turn off
1674 * the reflink flag if we unshare all of the file's blocks.
1677 xfs_reflink_unshare(
1678 struct xfs_inode *ip,
1682 struct xfs_mount *mp = ip->i_mount;
1688 if (!xfs_is_reflink_inode(ip))
1691 trace_xfs_reflink_unshare(ip, offset, len);
1693 inode_dio_wait(VFS_I(ip));
1695 /* Try to CoW the selected ranges */
1696 xfs_ilock(ip, XFS_ILOCK_EXCL);
1697 fbno = XFS_B_TO_FSBT(mp, offset);
1698 isize = i_size_read(VFS_I(ip));
1699 end = XFS_B_TO_FSB(mp, offset + len);
1700 error = xfs_reflink_dirty_extents(ip, fbno, end, isize);
1703 xfs_iunlock(ip, XFS_ILOCK_EXCL);
1705 /* Wait for the IO to finish */
1706 error = filemap_write_and_wait(VFS_I(ip)->i_mapping);
1710 /* Turn off the reflink flag if possible. */
1711 error = xfs_reflink_try_clear_inode_flag(ip);
1718 xfs_iunlock(ip, XFS_ILOCK_EXCL);
1720 trace_xfs_reflink_unshare_error(ip, error, _RET_IP_);