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1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Copyright (C) 2016 Oracle. All Rights Reserved.
4 * Author: Darrick J. Wong <darrick.wong@oracle.com>
5 */
6#include "xfs.h"
7#include "xfs_fs.h"
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"
16#include "xfs_bmap.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"
25#include "xfs_bit.h"
26#include "xfs_alloc.h"
27#include "xfs_quota.h"
28#include "xfs_reflink.h"
29#include "xfs_iomap.h"
30#include "xfs_ag.h"
31#include "xfs_ag_resv.h"
32#include "xfs_health.h"
33
34/*
35 * Copy on Write of Shared Blocks
36 *
37 * XFS must preserve "the usual" file semantics even when two files share
38 * the same physical blocks. This means that a write to one file must not
39 * alter the blocks in a different file; the way that we'll do that is
40 * through the use of a copy-on-write mechanism. At a high level, that
41 * means that when we want to write to a shared block, we allocate a new
42 * block, write the data to the new block, and if that succeeds we map the
43 * new block into the file.
44 *
45 * XFS provides a "delayed allocation" mechanism that defers the allocation
46 * of disk blocks to dirty-but-not-yet-mapped file blocks as long as
47 * possible. This reduces fragmentation by enabling the filesystem to ask
48 * for bigger chunks less often, which is exactly what we want for CoW.
49 *
50 * The delalloc mechanism begins when the kernel wants to make a block
51 * writable (write_begin or page_mkwrite). If the offset is not mapped, we
52 * create a delalloc mapping, which is a regular in-core extent, but without
53 * a real startblock. (For delalloc mappings, the startblock encodes both
54 * a flag that this is a delalloc mapping, and a worst-case estimate of how
55 * many blocks might be required to put the mapping into the BMBT.) delalloc
56 * mappings are a reservation against the free space in the filesystem;
57 * adjacent mappings can also be combined into fewer larger mappings.
58 *
59 * As an optimization, the CoW extent size hint (cowextsz) creates
60 * outsized aligned delalloc reservations in the hope of landing out of
61 * order nearby CoW writes in a single extent on disk, thereby reducing
62 * fragmentation and improving future performance.
63 *
64 * D: --RRRRRRSSSRRRRRRRR--- (data fork)
65 * C: ------DDDDDDD--------- (CoW fork)
66 *
67 * When dirty pages are being written out (typically in writepage), the
68 * delalloc reservations are converted into unwritten mappings by
69 * allocating blocks and replacing the delalloc mapping with real ones.
70 * A delalloc mapping can be replaced by several unwritten ones if the
71 * free space is fragmented.
72 *
73 * D: --RRRRRRSSSRRRRRRRR---
74 * C: ------UUUUUUU---------
75 *
76 * We want to adapt the delalloc mechanism for copy-on-write, since the
77 * write paths are similar. The first two steps (creating the reservation
78 * and allocating the blocks) are exactly the same as delalloc except that
79 * the mappings must be stored in a separate CoW fork because we do not want
80 * to disturb the mapping in the data fork until we're sure that the write
81 * succeeded. IO completion in this case is the process of removing the old
82 * mapping from the data fork and moving the new mapping from the CoW fork to
83 * the data fork. This will be discussed shortly.
84 *
85 * For now, unaligned directio writes will be bounced back to the page cache.
86 * Block-aligned directio writes will use the same mechanism as buffered
87 * writes.
88 *
89 * Just prior to submitting the actual disk write requests, we convert
90 * the extents representing the range of the file actually being written
91 * (as opposed to extra pieces created for the cowextsize hint) to real
92 * extents. This will become important in the next step:
93 *
94 * D: --RRRRRRSSSRRRRRRRR---
95 * C: ------UUrrUUU---------
96 *
97 * CoW remapping must be done after the data block write completes,
98 * because we don't want to destroy the old data fork map until we're sure
99 * the new block has been written. Since the new mappings are kept in a
100 * separate fork, we can simply iterate these mappings to find the ones
101 * that cover the file blocks that we just CoW'd. For each extent, simply
102 * unmap the corresponding range in the data fork, map the new range into
103 * the data fork, and remove the extent from the CoW fork. Because of
104 * the presence of the cowextsize hint, however, we must be careful
105 * only to remap the blocks that we've actually written out -- we must
106 * never remap delalloc reservations nor CoW staging blocks that have
107 * yet to be written. This corresponds exactly to the real extents in
108 * the CoW fork:
109 *
110 * D: --RRRRRRrrSRRRRRRRR---
111 * C: ------UU--UUU---------
112 *
113 * Since the remapping operation can be applied to an arbitrary file
114 * range, we record the need for the remap step as a flag in the ioend
115 * instead of declaring a new IO type. This is required for direct io
116 * because we only have ioend for the whole dio, and we have to be able to
117 * remember the presence of unwritten blocks and CoW blocks with a single
118 * ioend structure. Better yet, the more ground we can cover with one
119 * ioend, the better.
120 */
121
122/*
123 * Given an AG extent, find the lowest-numbered run of shared blocks
124 * within that range and return the range in fbno/flen. If
125 * find_end_of_shared is true, return the longest contiguous extent of
126 * shared blocks. If there are no shared extents, fbno and flen will
127 * be set to NULLAGBLOCK and 0, respectively.
128 */
129static int
130xfs_reflink_find_shared(
131 struct xfs_perag *pag,
132 struct xfs_trans *tp,
133 xfs_agblock_t agbno,
134 xfs_extlen_t aglen,
135 xfs_agblock_t *fbno,
136 xfs_extlen_t *flen,
137 bool find_end_of_shared)
138{
139 struct xfs_buf *agbp;
140 struct xfs_btree_cur *cur;
141 int error;
142
143 error = xfs_alloc_read_agf(pag, tp, 0, &agbp);
144 if (error)
145 return error;
146
147 cur = xfs_refcountbt_init_cursor(pag->pag_mount, tp, agbp, pag);
148
149 error = xfs_refcount_find_shared(cur, agbno, aglen, fbno, flen,
150 find_end_of_shared);
151
152 xfs_btree_del_cursor(cur, error);
153
154 xfs_trans_brelse(tp, agbp);
155 return error;
156}
157
158/*
159 * Trim the mapping to the next block where there's a change in the
160 * shared/unshared status. More specifically, this means that we
161 * find the lowest-numbered extent of shared blocks that coincides with
162 * the given block mapping. If the shared extent overlaps the start of
163 * the mapping, trim the mapping to the end of the shared extent. If
164 * the shared region intersects the mapping, trim the mapping to the
165 * start of the shared extent. If there are no shared regions that
166 * overlap, just return the original extent.
167 */
168int
169xfs_reflink_trim_around_shared(
170 struct xfs_inode *ip,
171 struct xfs_bmbt_irec *irec,
172 bool *shared)
173{
174 struct xfs_mount *mp = ip->i_mount;
175 struct xfs_perag *pag;
176 xfs_agblock_t agbno;
177 xfs_extlen_t aglen;
178 xfs_agblock_t fbno;
179 xfs_extlen_t flen;
180 int error = 0;
181
182 /* Holes, unwritten, and delalloc extents cannot be shared */
183 if (!xfs_is_cow_inode(ip) || !xfs_bmap_is_written_extent(irec)) {
184 *shared = false;
185 return 0;
186 }
187
188 trace_xfs_reflink_trim_around_shared(ip, irec);
189
190 pag = xfs_perag_get(mp, XFS_FSB_TO_AGNO(mp, irec->br_startblock));
191 agbno = XFS_FSB_TO_AGBNO(mp, irec->br_startblock);
192 aglen = irec->br_blockcount;
193
194 error = xfs_reflink_find_shared(pag, NULL, agbno, aglen, &fbno, &flen,
195 true);
196 xfs_perag_put(pag);
197 if (error)
198 return error;
199
200 *shared = false;
201 if (fbno == NULLAGBLOCK) {
202 /* No shared blocks at all. */
203 return 0;
204 }
205
206 if (fbno == agbno) {
207 /*
208 * The start of this extent is shared. Truncate the
209 * mapping at the end of the shared region so that a
210 * subsequent iteration starts at the start of the
211 * unshared region.
212 */
213 irec->br_blockcount = flen;
214 *shared = true;
215 return 0;
216 }
217
218 /*
219 * There's a shared extent midway through this extent.
220 * Truncate the mapping at the start of the shared
221 * extent so that a subsequent iteration starts at the
222 * start of the shared region.
223 */
224 irec->br_blockcount = fbno - agbno;
225 return 0;
226}
227
228int
229xfs_bmap_trim_cow(
230 struct xfs_inode *ip,
231 struct xfs_bmbt_irec *imap,
232 bool *shared)
233{
234 /* We can't update any real extents in always COW mode. */
235 if (xfs_is_always_cow_inode(ip) &&
236 !isnullstartblock(imap->br_startblock)) {
237 *shared = true;
238 return 0;
239 }
240
241 /* Trim the mapping to the nearest shared extent boundary. */
242 return xfs_reflink_trim_around_shared(ip, imap, shared);
243}
244
245static int
246xfs_reflink_convert_cow_locked(
247 struct xfs_inode *ip,
248 xfs_fileoff_t offset_fsb,
249 xfs_filblks_t count_fsb)
250{
251 struct xfs_iext_cursor icur;
252 struct xfs_bmbt_irec got;
253 struct xfs_btree_cur *dummy_cur = NULL;
254 int dummy_logflags;
255 int error = 0;
256
257 if (!xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &got))
258 return 0;
259
260 do {
261 if (got.br_startoff >= offset_fsb + count_fsb)
262 break;
263 if (got.br_state == XFS_EXT_NORM)
264 continue;
265 if (WARN_ON_ONCE(isnullstartblock(got.br_startblock)))
266 return -EIO;
267
268 xfs_trim_extent(&got, offset_fsb, count_fsb);
269 if (!got.br_blockcount)
270 continue;
271
272 got.br_state = XFS_EXT_NORM;
273 error = xfs_bmap_add_extent_unwritten_real(NULL, ip,
274 XFS_COW_FORK, &icur, &dummy_cur, &got,
275 &dummy_logflags);
276 if (error)
277 return error;
278 } while (xfs_iext_next_extent(ip->i_cowfp, &icur, &got));
279
280 return error;
281}
282
283/* Convert all of the unwritten CoW extents in a file's range to real ones. */
284int
285xfs_reflink_convert_cow(
286 struct xfs_inode *ip,
287 xfs_off_t offset,
288 xfs_off_t count)
289{
290 struct xfs_mount *mp = ip->i_mount;
291 xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset);
292 xfs_fileoff_t end_fsb = XFS_B_TO_FSB(mp, offset + count);
293 xfs_filblks_t count_fsb = end_fsb - offset_fsb;
294 int error;
295
296 ASSERT(count != 0);
297
298 xfs_ilock(ip, XFS_ILOCK_EXCL);
299 error = xfs_reflink_convert_cow_locked(ip, offset_fsb, count_fsb);
300 xfs_iunlock(ip, XFS_ILOCK_EXCL);
301 return error;
302}
303
304/*
305 * Find the extent that maps the given range in the COW fork. Even if the extent
306 * is not shared we might have a preallocation for it in the COW fork. If so we
307 * use it that rather than trigger a new allocation.
308 */
309static int
310xfs_find_trim_cow_extent(
311 struct xfs_inode *ip,
312 struct xfs_bmbt_irec *imap,
313 struct xfs_bmbt_irec *cmap,
314 bool *shared,
315 bool *found)
316{
317 xfs_fileoff_t offset_fsb = imap->br_startoff;
318 xfs_filblks_t count_fsb = imap->br_blockcount;
319 struct xfs_iext_cursor icur;
320
321 *found = false;
322
323 /*
324 * If we don't find an overlapping extent, trim the range we need to
325 * allocate to fit the hole we found.
326 */
327 if (!xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, cmap))
328 cmap->br_startoff = offset_fsb + count_fsb;
329 if (cmap->br_startoff > offset_fsb) {
330 xfs_trim_extent(imap, imap->br_startoff,
331 cmap->br_startoff - imap->br_startoff);
332 return xfs_bmap_trim_cow(ip, imap, shared);
333 }
334
335 *shared = true;
336 if (isnullstartblock(cmap->br_startblock)) {
337 xfs_trim_extent(imap, cmap->br_startoff, cmap->br_blockcount);
338 return 0;
339 }
340
341 /* real extent found - no need to allocate */
342 xfs_trim_extent(cmap, offset_fsb, count_fsb);
343 *found = true;
344 return 0;
345}
346
347static int
348xfs_reflink_convert_unwritten(
349 struct xfs_inode *ip,
350 struct xfs_bmbt_irec *imap,
351 struct xfs_bmbt_irec *cmap,
352 bool convert_now)
353{
354 xfs_fileoff_t offset_fsb = imap->br_startoff;
355 xfs_filblks_t count_fsb = imap->br_blockcount;
356 int error;
357
358 /*
359 * cmap might larger than imap due to cowextsize hint.
360 */
361 xfs_trim_extent(cmap, offset_fsb, count_fsb);
362
363 /*
364 * COW fork extents are supposed to remain unwritten until we're ready
365 * to initiate a disk write. For direct I/O we are going to write the
366 * data and need the conversion, but for buffered writes we're done.
367 */
368 if (!convert_now || cmap->br_state == XFS_EXT_NORM)
369 return 0;
370
371 trace_xfs_reflink_convert_cow(ip, cmap);
372
373 error = xfs_reflink_convert_cow_locked(ip, offset_fsb, count_fsb);
374 if (!error)
375 cmap->br_state = XFS_EXT_NORM;
376
377 return error;
378}
379
380static int
381xfs_reflink_fill_cow_hole(
382 struct xfs_inode *ip,
383 struct xfs_bmbt_irec *imap,
384 struct xfs_bmbt_irec *cmap,
385 bool *shared,
386 uint *lockmode,
387 bool convert_now)
388{
389 struct xfs_mount *mp = ip->i_mount;
390 struct xfs_trans *tp;
391 xfs_filblks_t resaligned;
392 xfs_extlen_t resblks;
393 int nimaps;
394 int error;
395 bool found;
396
397 resaligned = xfs_aligned_fsb_count(imap->br_startoff,
398 imap->br_blockcount, xfs_get_cowextsz_hint(ip));
399 resblks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
400
401 xfs_iunlock(ip, *lockmode);
402 *lockmode = 0;
403
404 error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write, resblks, 0,
405 false, &tp);
406 if (error)
407 return error;
408
409 *lockmode = XFS_ILOCK_EXCL;
410
411 error = xfs_find_trim_cow_extent(ip, imap, cmap, shared, &found);
412 if (error || !*shared)
413 goto out_trans_cancel;
414
415 if (found) {
416 xfs_trans_cancel(tp);
417 goto convert;
418 }
419
420 /* Allocate the entire reservation as unwritten blocks. */
421 nimaps = 1;
422 error = xfs_bmapi_write(tp, ip, imap->br_startoff, imap->br_blockcount,
423 XFS_BMAPI_COWFORK | XFS_BMAPI_PREALLOC, 0, cmap,
424 &nimaps);
425 if (error)
426 goto out_trans_cancel;
427
428 xfs_inode_set_cowblocks_tag(ip);
429 error = xfs_trans_commit(tp);
430 if (error)
431 return error;
432
433 /*
434 * Allocation succeeded but the requested range was not even partially
435 * satisfied? Bail out!
436 */
437 if (nimaps == 0)
438 return -ENOSPC;
439
440convert:
441 return xfs_reflink_convert_unwritten(ip, imap, cmap, convert_now);
442
443out_trans_cancel:
444 xfs_trans_cancel(tp);
445 return error;
446}
447
448static int
449xfs_reflink_fill_delalloc(
450 struct xfs_inode *ip,
451 struct xfs_bmbt_irec *imap,
452 struct xfs_bmbt_irec *cmap,
453 bool *shared,
454 uint *lockmode,
455 bool convert_now)
456{
457 struct xfs_mount *mp = ip->i_mount;
458 struct xfs_trans *tp;
459 int nimaps;
460 int error;
461 bool found;
462
463 do {
464 xfs_iunlock(ip, *lockmode);
465 *lockmode = 0;
466
467 error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write, 0, 0,
468 false, &tp);
469 if (error)
470 return error;
471
472 *lockmode = XFS_ILOCK_EXCL;
473
474 error = xfs_find_trim_cow_extent(ip, imap, cmap, shared,
475 &found);
476 if (error || !*shared)
477 goto out_trans_cancel;
478
479 if (found) {
480 xfs_trans_cancel(tp);
481 break;
482 }
483
484 ASSERT(isnullstartblock(cmap->br_startblock) ||
485 cmap->br_startblock == DELAYSTARTBLOCK);
486
487 /*
488 * Replace delalloc reservation with an unwritten extent.
489 */
490 nimaps = 1;
491 error = xfs_bmapi_write(tp, ip, cmap->br_startoff,
492 cmap->br_blockcount,
493 XFS_BMAPI_COWFORK | XFS_BMAPI_PREALLOC, 0,
494 cmap, &nimaps);
495 if (error)
496 goto out_trans_cancel;
497
498 xfs_inode_set_cowblocks_tag(ip);
499 error = xfs_trans_commit(tp);
500 if (error)
501 return error;
502
503 /*
504 * Allocation succeeded but the requested range was not even
505 * partially satisfied? Bail out!
506 */
507 if (nimaps == 0)
508 return -ENOSPC;
509 } while (cmap->br_startoff + cmap->br_blockcount <= imap->br_startoff);
510
511 return xfs_reflink_convert_unwritten(ip, imap, cmap, convert_now);
512
513out_trans_cancel:
514 xfs_trans_cancel(tp);
515 return error;
516}
517
518/* Allocate all CoW reservations covering a range of blocks in a file. */
519int
520xfs_reflink_allocate_cow(
521 struct xfs_inode *ip,
522 struct xfs_bmbt_irec *imap,
523 struct xfs_bmbt_irec *cmap,
524 bool *shared,
525 uint *lockmode,
526 bool convert_now)
527{
528 int error;
529 bool found;
530
531 xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
532 if (!ip->i_cowfp) {
533 ASSERT(!xfs_is_reflink_inode(ip));
534 xfs_ifork_init_cow(ip);
535 }
536
537 error = xfs_find_trim_cow_extent(ip, imap, cmap, shared, &found);
538 if (error || !*shared)
539 return error;
540
541 /* CoW fork has a real extent */
542 if (found)
543 return xfs_reflink_convert_unwritten(ip, imap, cmap,
544 convert_now);
545
546 /*
547 * CoW fork does not have an extent and data extent is shared.
548 * Allocate a real extent in the CoW fork.
549 */
550 if (cmap->br_startoff > imap->br_startoff)
551 return xfs_reflink_fill_cow_hole(ip, imap, cmap, shared,
552 lockmode, convert_now);
553
554 /*
555 * CoW fork has a delalloc reservation. Replace it with a real extent.
556 * There may or may not be a data fork mapping.
557 */
558 if (isnullstartblock(cmap->br_startblock) ||
559 cmap->br_startblock == DELAYSTARTBLOCK)
560 return xfs_reflink_fill_delalloc(ip, imap, cmap, shared,
561 lockmode, convert_now);
562
563 /* Shouldn't get here. */
564 ASSERT(0);
565 return -EFSCORRUPTED;
566}
567
568/*
569 * Cancel CoW reservations for some block range of an inode.
570 *
571 * If cancel_real is true this function cancels all COW fork extents for the
572 * inode; if cancel_real is false, real extents are not cleared.
573 *
574 * Caller must have already joined the inode to the current transaction. The
575 * inode will be joined to the transaction returned to the caller.
576 */
577int
578xfs_reflink_cancel_cow_blocks(
579 struct xfs_inode *ip,
580 struct xfs_trans **tpp,
581 xfs_fileoff_t offset_fsb,
582 xfs_fileoff_t end_fsb,
583 bool cancel_real)
584{
585 struct xfs_ifork *ifp = xfs_ifork_ptr(ip, XFS_COW_FORK);
586 struct xfs_bmbt_irec got, del;
587 struct xfs_iext_cursor icur;
588 int error = 0;
589
590 if (!xfs_inode_has_cow_data(ip))
591 return 0;
592 if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &icur, &got))
593 return 0;
594
595 /* Walk backwards until we're out of the I/O range... */
596 while (got.br_startoff + got.br_blockcount > offset_fsb) {
597 del = got;
598 xfs_trim_extent(&del, offset_fsb, end_fsb - offset_fsb);
599
600 /* Extent delete may have bumped ext forward */
601 if (!del.br_blockcount) {
602 xfs_iext_prev(ifp, &icur);
603 goto next_extent;
604 }
605
606 trace_xfs_reflink_cancel_cow(ip, &del);
607
608 if (isnullstartblock(del.br_startblock)) {
609 error = xfs_bmap_del_extent_delay(ip, XFS_COW_FORK,
610 &icur, &got, &del);
611 if (error)
612 break;
613 } else if (del.br_state == XFS_EXT_UNWRITTEN || cancel_real) {
614 ASSERT((*tpp)->t_highest_agno == NULLAGNUMBER);
615
616 /* Free the CoW orphan record. */
617 xfs_refcount_free_cow_extent(*tpp, del.br_startblock,
618 del.br_blockcount);
619
620 error = xfs_free_extent_later(*tpp, del.br_startblock,
621 del.br_blockcount, NULL,
622 XFS_AG_RESV_NONE, false);
623 if (error)
624 break;
625
626 /* Roll the transaction */
627 error = xfs_defer_finish(tpp);
628 if (error)
629 break;
630
631 /* Remove the mapping from the CoW fork. */
632 xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
633
634 /* Remove the quota reservation */
635 error = xfs_quota_unreserve_blkres(ip,
636 del.br_blockcount);
637 if (error)
638 break;
639 } else {
640 /* Didn't do anything, push cursor back. */
641 xfs_iext_prev(ifp, &icur);
642 }
643next_extent:
644 if (!xfs_iext_get_extent(ifp, &icur, &got))
645 break;
646 }
647
648 /* clear tag if cow fork is emptied */
649 if (!ifp->if_bytes)
650 xfs_inode_clear_cowblocks_tag(ip);
651 return error;
652}
653
654/*
655 * Cancel CoW reservations for some byte range of an inode.
656 *
657 * If cancel_real is true this function cancels all COW fork extents for the
658 * inode; if cancel_real is false, real extents are not cleared.
659 */
660int
661xfs_reflink_cancel_cow_range(
662 struct xfs_inode *ip,
663 xfs_off_t offset,
664 xfs_off_t count,
665 bool cancel_real)
666{
667 struct xfs_trans *tp;
668 xfs_fileoff_t offset_fsb;
669 xfs_fileoff_t end_fsb;
670 int error;
671
672 trace_xfs_reflink_cancel_cow_range(ip, offset, count);
673 ASSERT(ip->i_cowfp);
674
675 offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
676 if (count == NULLFILEOFF)
677 end_fsb = NULLFILEOFF;
678 else
679 end_fsb = XFS_B_TO_FSB(ip->i_mount, offset + count);
680
681 /* Start a rolling transaction to remove the mappings */
682 error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_write,
683 0, 0, 0, &tp);
684 if (error)
685 goto out;
686
687 xfs_ilock(ip, XFS_ILOCK_EXCL);
688 xfs_trans_ijoin(tp, ip, 0);
689
690 /* Scrape out the old CoW reservations */
691 error = xfs_reflink_cancel_cow_blocks(ip, &tp, offset_fsb, end_fsb,
692 cancel_real);
693 if (error)
694 goto out_cancel;
695
696 error = xfs_trans_commit(tp);
697
698 xfs_iunlock(ip, XFS_ILOCK_EXCL);
699 return error;
700
701out_cancel:
702 xfs_trans_cancel(tp);
703 xfs_iunlock(ip, XFS_ILOCK_EXCL);
704out:
705 trace_xfs_reflink_cancel_cow_range_error(ip, error, _RET_IP_);
706 return error;
707}
708
709/*
710 * Remap part of the CoW fork into the data fork.
711 *
712 * We aim to remap the range starting at @offset_fsb and ending at @end_fsb
713 * into the data fork; this function will remap what it can (at the end of the
714 * range) and update @end_fsb appropriately. Each remap gets its own
715 * transaction because we can end up merging and splitting bmbt blocks for
716 * every remap operation and we'd like to keep the block reservation
717 * requirements as low as possible.
718 */
719STATIC int
720xfs_reflink_end_cow_extent(
721 struct xfs_inode *ip,
722 xfs_fileoff_t *offset_fsb,
723 xfs_fileoff_t end_fsb)
724{
725 struct xfs_iext_cursor icur;
726 struct xfs_bmbt_irec got, del, data;
727 struct xfs_mount *mp = ip->i_mount;
728 struct xfs_trans *tp;
729 struct xfs_ifork *ifp = xfs_ifork_ptr(ip, XFS_COW_FORK);
730 unsigned int resblks;
731 int nmaps;
732 int error;
733
734 /* No COW extents? That's easy! */
735 if (ifp->if_bytes == 0) {
736 *offset_fsb = end_fsb;
737 return 0;
738 }
739
740 resblks = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
741 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0,
742 XFS_TRANS_RESERVE, &tp);
743 if (error)
744 return error;
745
746 /*
747 * Lock the inode. We have to ijoin without automatic unlock because
748 * the lead transaction is the refcountbt record deletion; the data
749 * fork update follows as a deferred log item.
750 */
751 xfs_ilock(ip, XFS_ILOCK_EXCL);
752 xfs_trans_ijoin(tp, ip, 0);
753
754 error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
755 XFS_IEXT_REFLINK_END_COW_CNT);
756 if (error == -EFBIG)
757 error = xfs_iext_count_upgrade(tp, ip,
758 XFS_IEXT_REFLINK_END_COW_CNT);
759 if (error)
760 goto out_cancel;
761
762 /*
763 * In case of racing, overlapping AIO writes no COW extents might be
764 * left by the time I/O completes for the loser of the race. In that
765 * case we are done.
766 */
767 if (!xfs_iext_lookup_extent(ip, ifp, *offset_fsb, &icur, &got) ||
768 got.br_startoff >= end_fsb) {
769 *offset_fsb = end_fsb;
770 goto out_cancel;
771 }
772
773 /*
774 * Only remap real extents that contain data. With AIO, speculative
775 * preallocations can leak into the range we are called upon, and we
776 * need to skip them. Preserve @got for the eventual CoW fork
777 * deletion; from now on @del represents the mapping that we're
778 * actually remapping.
779 */
780 while (!xfs_bmap_is_written_extent(&got)) {
781 if (!xfs_iext_next_extent(ifp, &icur, &got) ||
782 got.br_startoff >= end_fsb) {
783 *offset_fsb = end_fsb;
784 goto out_cancel;
785 }
786 }
787 del = got;
788 xfs_trim_extent(&del, *offset_fsb, end_fsb - *offset_fsb);
789
790 /* Grab the corresponding mapping in the data fork. */
791 nmaps = 1;
792 error = xfs_bmapi_read(ip, del.br_startoff, del.br_blockcount, &data,
793 &nmaps, 0);
794 if (error)
795 goto out_cancel;
796
797 /* We can only remap the smaller of the two extent sizes. */
798 data.br_blockcount = min(data.br_blockcount, del.br_blockcount);
799 del.br_blockcount = data.br_blockcount;
800
801 trace_xfs_reflink_cow_remap_from(ip, &del);
802 trace_xfs_reflink_cow_remap_to(ip, &data);
803
804 if (xfs_bmap_is_real_extent(&data)) {
805 /*
806 * If the extent we're remapping is backed by storage (written
807 * or not), unmap the extent and drop its refcount.
808 */
809 xfs_bmap_unmap_extent(tp, ip, XFS_DATA_FORK, &data);
810 xfs_refcount_decrease_extent(tp, &data);
811 xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT,
812 -data.br_blockcount);
813 } else if (data.br_startblock == DELAYSTARTBLOCK) {
814 int done;
815
816 /*
817 * If the extent we're remapping is a delalloc reservation,
818 * we can use the regular bunmapi function to release the
819 * incore state. Dropping the delalloc reservation takes care
820 * of the quota reservation for us.
821 */
822 error = xfs_bunmapi(NULL, ip, data.br_startoff,
823 data.br_blockcount, 0, 1, &done);
824 if (error)
825 goto out_cancel;
826 ASSERT(done);
827 }
828
829 /* Free the CoW orphan record. */
830 xfs_refcount_free_cow_extent(tp, del.br_startblock, del.br_blockcount);
831
832 /* Map the new blocks into the data fork. */
833 xfs_bmap_map_extent(tp, ip, XFS_DATA_FORK, &del);
834
835 /* Charge this new data fork mapping to the on-disk quota. */
836 xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_DELBCOUNT,
837 (long)del.br_blockcount);
838
839 /* Remove the mapping from the CoW fork. */
840 xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
841
842 error = xfs_trans_commit(tp);
843 xfs_iunlock(ip, XFS_ILOCK_EXCL);
844 if (error)
845 return error;
846
847 /* Update the caller about how much progress we made. */
848 *offset_fsb = del.br_startoff + del.br_blockcount;
849 return 0;
850
851out_cancel:
852 xfs_trans_cancel(tp);
853 xfs_iunlock(ip, XFS_ILOCK_EXCL);
854 return error;
855}
856
857/*
858 * Remap parts of a file's data fork after a successful CoW.
859 */
860int
861xfs_reflink_end_cow(
862 struct xfs_inode *ip,
863 xfs_off_t offset,
864 xfs_off_t count)
865{
866 xfs_fileoff_t offset_fsb;
867 xfs_fileoff_t end_fsb;
868 int error = 0;
869
870 trace_xfs_reflink_end_cow(ip, offset, count);
871
872 offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
873 end_fsb = XFS_B_TO_FSB(ip->i_mount, offset + count);
874
875 /*
876 * Walk forwards until we've remapped the I/O range. The loop function
877 * repeatedly cycles the ILOCK to allocate one transaction per remapped
878 * extent.
879 *
880 * If we're being called by writeback then the pages will still
881 * have PageWriteback set, which prevents races with reflink remapping
882 * and truncate. Reflink remapping prevents races with writeback by
883 * taking the iolock and mmaplock before flushing the pages and
884 * remapping, which means there won't be any further writeback or page
885 * cache dirtying until the reflink completes.
886 *
887 * We should never have two threads issuing writeback for the same file
888 * region. There are also have post-eof checks in the writeback
889 * preparation code so that we don't bother writing out pages that are
890 * about to be truncated.
891 *
892 * If we're being called as part of directio write completion, the dio
893 * count is still elevated, which reflink and truncate will wait for.
894 * Reflink remapping takes the iolock and mmaplock and waits for
895 * pending dio to finish, which should prevent any directio until the
896 * remap completes. Multiple concurrent directio writes to the same
897 * region are handled by end_cow processing only occurring for the
898 * threads which succeed; the outcome of multiple overlapping direct
899 * writes is not well defined anyway.
900 *
901 * It's possible that a buffered write and a direct write could collide
902 * here (the buffered write stumbles in after the dio flushes and
903 * invalidates the page cache and immediately queues writeback), but we
904 * have never supported this 100%. If either disk write succeeds the
905 * blocks will be remapped.
906 */
907 while (end_fsb > offset_fsb && !error)
908 error = xfs_reflink_end_cow_extent(ip, &offset_fsb, end_fsb);
909
910 if (error)
911 trace_xfs_reflink_end_cow_error(ip, error, _RET_IP_);
912 return error;
913}
914
915/*
916 * Free all CoW staging blocks that are still referenced by the ondisk refcount
917 * metadata. The ondisk metadata does not track which inode created the
918 * staging extent, so callers must ensure that there are no cached inodes with
919 * live CoW staging extents.
920 */
921int
922xfs_reflink_recover_cow(
923 struct xfs_mount *mp)
924{
925 struct xfs_perag *pag;
926 xfs_agnumber_t agno;
927 int error = 0;
928
929 if (!xfs_has_reflink(mp))
930 return 0;
931
932 for_each_perag(mp, agno, pag) {
933 error = xfs_refcount_recover_cow_leftovers(mp, pag);
934 if (error) {
935 xfs_perag_rele(pag);
936 break;
937 }
938 }
939
940 return error;
941}
942
943/*
944 * Reflinking (Block) Ranges of Two Files Together
945 *
946 * First, ensure that the reflink flag is set on both inodes. The flag is an
947 * optimization to avoid unnecessary refcount btree lookups in the write path.
948 *
949 * Now we can iteratively remap the range of extents (and holes) in src to the
950 * corresponding ranges in dest. Let drange and srange denote the ranges of
951 * logical blocks in dest and src touched by the reflink operation.
952 *
953 * While the length of drange is greater than zero,
954 * - Read src's bmbt at the start of srange ("imap")
955 * - If imap doesn't exist, make imap appear to start at the end of srange
956 * with zero length.
957 * - If imap starts before srange, advance imap to start at srange.
958 * - If imap goes beyond srange, truncate imap to end at the end of srange.
959 * - Punch (imap start - srange start + imap len) blocks from dest at
960 * offset (drange start).
961 * - If imap points to a real range of pblks,
962 * > Increase the refcount of the imap's pblks
963 * > Map imap's pblks into dest at the offset
964 * (drange start + imap start - srange start)
965 * - Advance drange and srange by (imap start - srange start + imap len)
966 *
967 * Finally, if the reflink made dest longer, update both the in-core and
968 * on-disk file sizes.
969 *
970 * ASCII Art Demonstration:
971 *
972 * Let's say we want to reflink this source file:
973 *
974 * ----SSSSSSS-SSSSS----SSSSSS (src file)
975 * <-------------------->
976 *
977 * into this destination file:
978 *
979 * --DDDDDDDDDDDDDDDDDDD--DDD (dest file)
980 * <-------------------->
981 * '-' means a hole, and 'S' and 'D' are written blocks in the src and dest.
982 * Observe that the range has different logical offsets in either file.
983 *
984 * Consider that the first extent in the source file doesn't line up with our
985 * reflink range. Unmapping and remapping are separate operations, so we can
986 * unmap more blocks from the destination file than we remap.
987 *
988 * ----SSSSSSS-SSSSS----SSSSSS
989 * <------->
990 * --DDDDD---------DDDDD--DDD
991 * <------->
992 *
993 * Now remap the source extent into the destination file:
994 *
995 * ----SSSSSSS-SSSSS----SSSSSS
996 * <------->
997 * --DDDDD--SSSSSSSDDDDD--DDD
998 * <------->
999 *
1000 * Do likewise with the second hole and extent in our range. Holes in the
1001 * unmap range don't affect our operation.
1002 *
1003 * ----SSSSSSS-SSSSS----SSSSSS
1004 * <---->
1005 * --DDDDD--SSSSSSS-SSSSS-DDD
1006 * <---->
1007 *
1008 * Finally, unmap and remap part of the third extent. This will increase the
1009 * size of the destination file.
1010 *
1011 * ----SSSSSSS-SSSSS----SSSSSS
1012 * <----->
1013 * --DDDDD--SSSSSSS-SSSSS----SSS
1014 * <----->
1015 *
1016 * Once we update the destination file's i_size, we're done.
1017 */
1018
1019/*
1020 * Ensure the reflink bit is set in both inodes.
1021 */
1022STATIC int
1023xfs_reflink_set_inode_flag(
1024 struct xfs_inode *src,
1025 struct xfs_inode *dest)
1026{
1027 struct xfs_mount *mp = src->i_mount;
1028 int error;
1029 struct xfs_trans *tp;
1030
1031 if (xfs_is_reflink_inode(src) && xfs_is_reflink_inode(dest))
1032 return 0;
1033
1034 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
1035 if (error)
1036 goto out_error;
1037
1038 /* Lock both files against IO */
1039 if (src->i_ino == dest->i_ino)
1040 xfs_ilock(src, XFS_ILOCK_EXCL);
1041 else
1042 xfs_lock_two_inodes(src, XFS_ILOCK_EXCL, dest, XFS_ILOCK_EXCL);
1043
1044 if (!xfs_is_reflink_inode(src)) {
1045 trace_xfs_reflink_set_inode_flag(src);
1046 xfs_trans_ijoin(tp, src, XFS_ILOCK_EXCL);
1047 src->i_diflags2 |= XFS_DIFLAG2_REFLINK;
1048 xfs_trans_log_inode(tp, src, XFS_ILOG_CORE);
1049 xfs_ifork_init_cow(src);
1050 } else
1051 xfs_iunlock(src, XFS_ILOCK_EXCL);
1052
1053 if (src->i_ino == dest->i_ino)
1054 goto commit_flags;
1055
1056 if (!xfs_is_reflink_inode(dest)) {
1057 trace_xfs_reflink_set_inode_flag(dest);
1058 xfs_trans_ijoin(tp, dest, XFS_ILOCK_EXCL);
1059 dest->i_diflags2 |= XFS_DIFLAG2_REFLINK;
1060 xfs_trans_log_inode(tp, dest, XFS_ILOG_CORE);
1061 xfs_ifork_init_cow(dest);
1062 } else
1063 xfs_iunlock(dest, XFS_ILOCK_EXCL);
1064
1065commit_flags:
1066 error = xfs_trans_commit(tp);
1067 if (error)
1068 goto out_error;
1069 return error;
1070
1071out_error:
1072 trace_xfs_reflink_set_inode_flag_error(dest, error, _RET_IP_);
1073 return error;
1074}
1075
1076/*
1077 * Update destination inode size & cowextsize hint, if necessary.
1078 */
1079int
1080xfs_reflink_update_dest(
1081 struct xfs_inode *dest,
1082 xfs_off_t newlen,
1083 xfs_extlen_t cowextsize,
1084 unsigned int remap_flags)
1085{
1086 struct xfs_mount *mp = dest->i_mount;
1087 struct xfs_trans *tp;
1088 int error;
1089
1090 if (newlen <= i_size_read(VFS_I(dest)) && cowextsize == 0)
1091 return 0;
1092
1093 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
1094 if (error)
1095 goto out_error;
1096
1097 xfs_ilock(dest, XFS_ILOCK_EXCL);
1098 xfs_trans_ijoin(tp, dest, XFS_ILOCK_EXCL);
1099
1100 if (newlen > i_size_read(VFS_I(dest))) {
1101 trace_xfs_reflink_update_inode_size(dest, newlen);
1102 i_size_write(VFS_I(dest), newlen);
1103 dest->i_disk_size = newlen;
1104 }
1105
1106 if (cowextsize) {
1107 dest->i_cowextsize = cowextsize;
1108 dest->i_diflags2 |= XFS_DIFLAG2_COWEXTSIZE;
1109 }
1110
1111 xfs_trans_log_inode(tp, dest, XFS_ILOG_CORE);
1112
1113 error = xfs_trans_commit(tp);
1114 if (error)
1115 goto out_error;
1116 return error;
1117
1118out_error:
1119 trace_xfs_reflink_update_inode_size_error(dest, error, _RET_IP_);
1120 return error;
1121}
1122
1123/*
1124 * Do we have enough reserve in this AG to handle a reflink? The refcount
1125 * btree already reserved all the space it needs, but the rmap btree can grow
1126 * infinitely, so we won't allow more reflinks when the AG is down to the
1127 * btree reserves.
1128 */
1129static int
1130xfs_reflink_ag_has_free_space(
1131 struct xfs_mount *mp,
1132 xfs_agnumber_t agno)
1133{
1134 struct xfs_perag *pag;
1135 int error = 0;
1136
1137 if (!xfs_has_rmapbt(mp))
1138 return 0;
1139
1140 pag = xfs_perag_get(mp, agno);
1141 if (xfs_ag_resv_critical(pag, XFS_AG_RESV_RMAPBT) ||
1142 xfs_ag_resv_critical(pag, XFS_AG_RESV_METADATA))
1143 error = -ENOSPC;
1144 xfs_perag_put(pag);
1145 return error;
1146}
1147
1148/*
1149 * Remap the given extent into the file. The dmap blockcount will be set to
1150 * the number of blocks that were actually remapped.
1151 */
1152STATIC int
1153xfs_reflink_remap_extent(
1154 struct xfs_inode *ip,
1155 struct xfs_bmbt_irec *dmap,
1156 xfs_off_t new_isize)
1157{
1158 struct xfs_bmbt_irec smap;
1159 struct xfs_mount *mp = ip->i_mount;
1160 struct xfs_trans *tp;
1161 xfs_off_t newlen;
1162 int64_t qdelta = 0;
1163 unsigned int resblks;
1164 bool quota_reserved = true;
1165 bool smap_real;
1166 bool dmap_written = xfs_bmap_is_written_extent(dmap);
1167 int iext_delta = 0;
1168 int nimaps;
1169 int error;
1170
1171 /*
1172 * Start a rolling transaction to switch the mappings.
1173 *
1174 * Adding a written extent to the extent map can cause a bmbt split,
1175 * and removing a mapped extent from the extent can cause a bmbt split.
1176 * The two operations cannot both cause a split since they operate on
1177 * the same index in the bmap btree, so we only need a reservation for
1178 * one bmbt split if either thing is happening. However, we haven't
1179 * locked the inode yet, so we reserve assuming this is the case.
1180 *
1181 * The first allocation call tries to reserve enough space to handle
1182 * mapping dmap into a sparse part of the file plus the bmbt split. We
1183 * haven't locked the inode or read the existing mapping yet, so we do
1184 * not know for sure that we need the space. This should succeed most
1185 * of the time.
1186 *
1187 * If the first attempt fails, try again but reserving only enough
1188 * space to handle a bmbt split. This is the hard minimum requirement,
1189 * and we revisit quota reservations later when we know more about what
1190 * we're remapping.
1191 */
1192 resblks = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
1193 error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write,
1194 resblks + dmap->br_blockcount, 0, false, &tp);
1195 if (error == -EDQUOT || error == -ENOSPC) {
1196 quota_reserved = false;
1197 error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write,
1198 resblks, 0, false, &tp);
1199 }
1200 if (error)
1201 goto out;
1202
1203 /*
1204 * Read what's currently mapped in the destination file into smap.
1205 * If smap isn't a hole, we will have to remove it before we can add
1206 * dmap to the destination file.
1207 */
1208 nimaps = 1;
1209 error = xfs_bmapi_read(ip, dmap->br_startoff, dmap->br_blockcount,
1210 &smap, &nimaps, 0);
1211 if (error)
1212 goto out_cancel;
1213 ASSERT(nimaps == 1 && smap.br_startoff == dmap->br_startoff);
1214 smap_real = xfs_bmap_is_real_extent(&smap);
1215
1216 /*
1217 * We can only remap as many blocks as the smaller of the two extent
1218 * maps, because we can only remap one extent at a time.
1219 */
1220 dmap->br_blockcount = min(dmap->br_blockcount, smap.br_blockcount);
1221 ASSERT(dmap->br_blockcount == smap.br_blockcount);
1222
1223 trace_xfs_reflink_remap_extent_dest(ip, &smap);
1224
1225 /*
1226 * Two extents mapped to the same physical block must not have
1227 * different states; that's filesystem corruption. Move on to the next
1228 * extent if they're both holes or both the same physical extent.
1229 */
1230 if (dmap->br_startblock == smap.br_startblock) {
1231 if (dmap->br_state != smap.br_state) {
1232 xfs_bmap_mark_sick(ip, XFS_DATA_FORK);
1233 error = -EFSCORRUPTED;
1234 }
1235 goto out_cancel;
1236 }
1237
1238 /* If both extents are unwritten, leave them alone. */
1239 if (dmap->br_state == XFS_EXT_UNWRITTEN &&
1240 smap.br_state == XFS_EXT_UNWRITTEN)
1241 goto out_cancel;
1242
1243 /* No reflinking if the AG of the dest mapping is low on space. */
1244 if (dmap_written) {
1245 error = xfs_reflink_ag_has_free_space(mp,
1246 XFS_FSB_TO_AGNO(mp, dmap->br_startblock));
1247 if (error)
1248 goto out_cancel;
1249 }
1250
1251 /*
1252 * Increase quota reservation if we think the quota block counter for
1253 * this file could increase.
1254 *
1255 * If we are mapping a written extent into the file, we need to have
1256 * enough quota block count reservation to handle the blocks in that
1257 * extent. We log only the delta to the quota block counts, so if the
1258 * extent we're unmapping also has blocks allocated to it, we don't
1259 * need a quota reservation for the extent itself.
1260 *
1261 * Note that if we're replacing a delalloc reservation with a written
1262 * extent, we have to take the full quota reservation because removing
1263 * the delalloc reservation gives the block count back to the quota
1264 * count. This is suboptimal, but the VFS flushed the dest range
1265 * before we started. That should have removed all the delalloc
1266 * reservations, but we code defensively.
1267 *
1268 * xfs_trans_alloc_inode above already tried to grab an even larger
1269 * quota reservation, and kicked off a blockgc scan if it couldn't.
1270 * If we can't get a potentially smaller quota reservation now, we're
1271 * done.
1272 */
1273 if (!quota_reserved && !smap_real && dmap_written) {
1274 error = xfs_trans_reserve_quota_nblks(tp, ip,
1275 dmap->br_blockcount, 0, false);
1276 if (error)
1277 goto out_cancel;
1278 }
1279
1280 if (smap_real)
1281 ++iext_delta;
1282
1283 if (dmap_written)
1284 ++iext_delta;
1285
1286 error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK, iext_delta);
1287 if (error == -EFBIG)
1288 error = xfs_iext_count_upgrade(tp, ip, iext_delta);
1289 if (error)
1290 goto out_cancel;
1291
1292 if (smap_real) {
1293 /*
1294 * If the extent we're unmapping is backed by storage (written
1295 * or not), unmap the extent and drop its refcount.
1296 */
1297 xfs_bmap_unmap_extent(tp, ip, XFS_DATA_FORK, &smap);
1298 xfs_refcount_decrease_extent(tp, &smap);
1299 qdelta -= smap.br_blockcount;
1300 } else if (smap.br_startblock == DELAYSTARTBLOCK) {
1301 int done;
1302
1303 /*
1304 * If the extent we're unmapping is a delalloc reservation,
1305 * we can use the regular bunmapi function to release the
1306 * incore state. Dropping the delalloc reservation takes care
1307 * of the quota reservation for us.
1308 */
1309 error = xfs_bunmapi(NULL, ip, smap.br_startoff,
1310 smap.br_blockcount, 0, 1, &done);
1311 if (error)
1312 goto out_cancel;
1313 ASSERT(done);
1314 }
1315
1316 /*
1317 * If the extent we're sharing is backed by written storage, increase
1318 * its refcount and map it into the file.
1319 */
1320 if (dmap_written) {
1321 xfs_refcount_increase_extent(tp, dmap);
1322 xfs_bmap_map_extent(tp, ip, XFS_DATA_FORK, dmap);
1323 qdelta += dmap->br_blockcount;
1324 }
1325
1326 xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT, qdelta);
1327
1328 /* Update dest isize if needed. */
1329 newlen = XFS_FSB_TO_B(mp, dmap->br_startoff + dmap->br_blockcount);
1330 newlen = min_t(xfs_off_t, newlen, new_isize);
1331 if (newlen > i_size_read(VFS_I(ip))) {
1332 trace_xfs_reflink_update_inode_size(ip, newlen);
1333 i_size_write(VFS_I(ip), newlen);
1334 ip->i_disk_size = newlen;
1335 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
1336 }
1337
1338 /* Commit everything and unlock. */
1339 error = xfs_trans_commit(tp);
1340 goto out_unlock;
1341
1342out_cancel:
1343 xfs_trans_cancel(tp);
1344out_unlock:
1345 xfs_iunlock(ip, XFS_ILOCK_EXCL);
1346out:
1347 if (error)
1348 trace_xfs_reflink_remap_extent_error(ip, error, _RET_IP_);
1349 return error;
1350}
1351
1352/* Remap a range of one file to the other. */
1353int
1354xfs_reflink_remap_blocks(
1355 struct xfs_inode *src,
1356 loff_t pos_in,
1357 struct xfs_inode *dest,
1358 loff_t pos_out,
1359 loff_t remap_len,
1360 loff_t *remapped)
1361{
1362 struct xfs_bmbt_irec imap;
1363 struct xfs_mount *mp = src->i_mount;
1364 xfs_fileoff_t srcoff = XFS_B_TO_FSBT(mp, pos_in);
1365 xfs_fileoff_t destoff = XFS_B_TO_FSBT(mp, pos_out);
1366 xfs_filblks_t len;
1367 xfs_filblks_t remapped_len = 0;
1368 xfs_off_t new_isize = pos_out + remap_len;
1369 int nimaps;
1370 int error = 0;
1371
1372 len = min_t(xfs_filblks_t, XFS_B_TO_FSB(mp, remap_len),
1373 XFS_MAX_FILEOFF);
1374
1375 trace_xfs_reflink_remap_blocks(src, srcoff, len, dest, destoff);
1376
1377 while (len > 0) {
1378 unsigned int lock_mode;
1379
1380 /* Read extent from the source file */
1381 nimaps = 1;
1382 lock_mode = xfs_ilock_data_map_shared(src);
1383 error = xfs_bmapi_read(src, srcoff, len, &imap, &nimaps, 0);
1384 xfs_iunlock(src, lock_mode);
1385 if (error)
1386 break;
1387 /*
1388 * The caller supposedly flushed all dirty pages in the source
1389 * file range, which means that writeback should have allocated
1390 * or deleted all delalloc reservations in that range. If we
1391 * find one, that's a good sign that something is seriously
1392 * wrong here.
1393 */
1394 ASSERT(nimaps == 1 && imap.br_startoff == srcoff);
1395 if (imap.br_startblock == DELAYSTARTBLOCK) {
1396 ASSERT(imap.br_startblock != DELAYSTARTBLOCK);
1397 xfs_bmap_mark_sick(src, XFS_DATA_FORK);
1398 error = -EFSCORRUPTED;
1399 break;
1400 }
1401
1402 trace_xfs_reflink_remap_extent_src(src, &imap);
1403
1404 /* Remap into the destination file at the given offset. */
1405 imap.br_startoff = destoff;
1406 error = xfs_reflink_remap_extent(dest, &imap, new_isize);
1407 if (error)
1408 break;
1409
1410 if (fatal_signal_pending(current)) {
1411 error = -EINTR;
1412 break;
1413 }
1414
1415 /* Advance drange/srange */
1416 srcoff += imap.br_blockcount;
1417 destoff += imap.br_blockcount;
1418 len -= imap.br_blockcount;
1419 remapped_len += imap.br_blockcount;
1420 }
1421
1422 if (error)
1423 trace_xfs_reflink_remap_blocks_error(dest, error, _RET_IP_);
1424 *remapped = min_t(loff_t, remap_len,
1425 XFS_FSB_TO_B(src->i_mount, remapped_len));
1426 return error;
1427}
1428
1429/*
1430 * If we're reflinking to a point past the destination file's EOF, we must
1431 * zero any speculative post-EOF preallocations that sit between the old EOF
1432 * and the destination file offset.
1433 */
1434static int
1435xfs_reflink_zero_posteof(
1436 struct xfs_inode *ip,
1437 loff_t pos)
1438{
1439 loff_t isize = i_size_read(VFS_I(ip));
1440
1441 if (pos <= isize)
1442 return 0;
1443
1444 trace_xfs_zero_eof(ip, isize, pos - isize);
1445 return xfs_zero_range(ip, isize, pos - isize, NULL);
1446}
1447
1448/*
1449 * Prepare two files for range cloning. Upon a successful return both inodes
1450 * will have the iolock and mmaplock held, the page cache of the out file will
1451 * be truncated, and any leases on the out file will have been broken. This
1452 * function borrows heavily from xfs_file_aio_write_checks.
1453 *
1454 * The VFS allows partial EOF blocks to "match" for dedupe even though it hasn't
1455 * checked that the bytes beyond EOF physically match. Hence we cannot use the
1456 * EOF block in the source dedupe range because it's not a complete block match,
1457 * hence can introduce a corruption into the file that has it's block replaced.
1458 *
1459 * In similar fashion, the VFS file cloning also allows partial EOF blocks to be
1460 * "block aligned" for the purposes of cloning entire files. However, if the
1461 * source file range includes the EOF block and it lands within the existing EOF
1462 * of the destination file, then we can expose stale data from beyond the source
1463 * file EOF in the destination file.
1464 *
1465 * XFS doesn't support partial block sharing, so in both cases we have check
1466 * these cases ourselves. For dedupe, we can simply round the length to dedupe
1467 * down to the previous whole block and ignore the partial EOF block. While this
1468 * means we can't dedupe the last block of a file, this is an acceptible
1469 * tradeoff for simplicity on implementation.
1470 *
1471 * For cloning, we want to share the partial EOF block if it is also the new EOF
1472 * block of the destination file. If the partial EOF block lies inside the
1473 * existing destination EOF, then we have to abort the clone to avoid exposing
1474 * stale data in the destination file. Hence we reject these clone attempts with
1475 * -EINVAL in this case.
1476 */
1477int
1478xfs_reflink_remap_prep(
1479 struct file *file_in,
1480 loff_t pos_in,
1481 struct file *file_out,
1482 loff_t pos_out,
1483 loff_t *len,
1484 unsigned int remap_flags)
1485{
1486 struct inode *inode_in = file_inode(file_in);
1487 struct xfs_inode *src = XFS_I(inode_in);
1488 struct inode *inode_out = file_inode(file_out);
1489 struct xfs_inode *dest = XFS_I(inode_out);
1490 int ret;
1491
1492 /* Lock both files against IO */
1493 ret = xfs_ilock2_io_mmap(src, dest);
1494 if (ret)
1495 return ret;
1496
1497 /* Check file eligibility and prepare for block sharing. */
1498 ret = -EINVAL;
1499 /* Don't reflink realtime inodes */
1500 if (XFS_IS_REALTIME_INODE(src) || XFS_IS_REALTIME_INODE(dest))
1501 goto out_unlock;
1502
1503 /* Don't share DAX file data with non-DAX file. */
1504 if (IS_DAX(inode_in) != IS_DAX(inode_out))
1505 goto out_unlock;
1506
1507 if (!IS_DAX(inode_in))
1508 ret = generic_remap_file_range_prep(file_in, pos_in, file_out,
1509 pos_out, len, remap_flags);
1510 else
1511 ret = dax_remap_file_range_prep(file_in, pos_in, file_out,
1512 pos_out, len, remap_flags, &xfs_read_iomap_ops);
1513 if (ret || *len == 0)
1514 goto out_unlock;
1515
1516 /* Attach dquots to dest inode before changing block map */
1517 ret = xfs_qm_dqattach(dest);
1518 if (ret)
1519 goto out_unlock;
1520
1521 /*
1522 * Zero existing post-eof speculative preallocations in the destination
1523 * file.
1524 */
1525 ret = xfs_reflink_zero_posteof(dest, pos_out);
1526 if (ret)
1527 goto out_unlock;
1528
1529 /* Set flags and remap blocks. */
1530 ret = xfs_reflink_set_inode_flag(src, dest);
1531 if (ret)
1532 goto out_unlock;
1533
1534 /*
1535 * If pos_out > EOF, we may have dirtied blocks between EOF and
1536 * pos_out. In that case, we need to extend the flush and unmap to cover
1537 * from EOF to the end of the copy length.
1538 */
1539 if (pos_out > XFS_ISIZE(dest)) {
1540 loff_t flen = *len + (pos_out - XFS_ISIZE(dest));
1541 ret = xfs_flush_unmap_range(dest, XFS_ISIZE(dest), flen);
1542 } else {
1543 ret = xfs_flush_unmap_range(dest, pos_out, *len);
1544 }
1545 if (ret)
1546 goto out_unlock;
1547
1548 xfs_iflags_set(src, XFS_IREMAPPING);
1549 if (inode_in != inode_out)
1550 xfs_ilock_demote(src, XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL);
1551
1552 return 0;
1553out_unlock:
1554 xfs_iunlock2_io_mmap(src, dest);
1555 return ret;
1556}
1557
1558/* Does this inode need the reflink flag? */
1559int
1560xfs_reflink_inode_has_shared_extents(
1561 struct xfs_trans *tp,
1562 struct xfs_inode *ip,
1563 bool *has_shared)
1564{
1565 struct xfs_bmbt_irec got;
1566 struct xfs_mount *mp = ip->i_mount;
1567 struct xfs_ifork *ifp;
1568 struct xfs_iext_cursor icur;
1569 bool found;
1570 int error;
1571
1572 ifp = xfs_ifork_ptr(ip, XFS_DATA_FORK);
1573 error = xfs_iread_extents(tp, ip, XFS_DATA_FORK);
1574 if (error)
1575 return error;
1576
1577 *has_shared = false;
1578 found = xfs_iext_lookup_extent(ip, ifp, 0, &icur, &got);
1579 while (found) {
1580 struct xfs_perag *pag;
1581 xfs_agblock_t agbno;
1582 xfs_extlen_t aglen;
1583 xfs_agblock_t rbno;
1584 xfs_extlen_t rlen;
1585
1586 if (isnullstartblock(got.br_startblock) ||
1587 got.br_state != XFS_EXT_NORM)
1588 goto next;
1589
1590 pag = xfs_perag_get(mp, XFS_FSB_TO_AGNO(mp, got.br_startblock));
1591 agbno = XFS_FSB_TO_AGBNO(mp, got.br_startblock);
1592 aglen = got.br_blockcount;
1593 error = xfs_reflink_find_shared(pag, tp, agbno, aglen,
1594 &rbno, &rlen, false);
1595 xfs_perag_put(pag);
1596 if (error)
1597 return error;
1598
1599 /* Is there still a shared block here? */
1600 if (rbno != NULLAGBLOCK) {
1601 *has_shared = true;
1602 return 0;
1603 }
1604next:
1605 found = xfs_iext_next_extent(ifp, &icur, &got);
1606 }
1607
1608 return 0;
1609}
1610
1611/*
1612 * Clear the inode reflink flag if there are no shared extents.
1613 *
1614 * The caller is responsible for joining the inode to the transaction passed in.
1615 * The inode will be joined to the transaction that is returned to the caller.
1616 */
1617int
1618xfs_reflink_clear_inode_flag(
1619 struct xfs_inode *ip,
1620 struct xfs_trans **tpp)
1621{
1622 bool needs_flag;
1623 int error = 0;
1624
1625 ASSERT(xfs_is_reflink_inode(ip));
1626
1627 error = xfs_reflink_inode_has_shared_extents(*tpp, ip, &needs_flag);
1628 if (error || needs_flag)
1629 return error;
1630
1631 /*
1632 * We didn't find any shared blocks so turn off the reflink flag.
1633 * First, get rid of any leftover CoW mappings.
1634 */
1635 error = xfs_reflink_cancel_cow_blocks(ip, tpp, 0, XFS_MAX_FILEOFF,
1636 true);
1637 if (error)
1638 return error;
1639
1640 /* Clear the inode flag. */
1641 trace_xfs_reflink_unset_inode_flag(ip);
1642 ip->i_diflags2 &= ~XFS_DIFLAG2_REFLINK;
1643 xfs_inode_clear_cowblocks_tag(ip);
1644 xfs_trans_log_inode(*tpp, ip, XFS_ILOG_CORE);
1645
1646 return error;
1647}
1648
1649/*
1650 * Clear the inode reflink flag if there are no shared extents and the size
1651 * hasn't changed.
1652 */
1653STATIC int
1654xfs_reflink_try_clear_inode_flag(
1655 struct xfs_inode *ip)
1656{
1657 struct xfs_mount *mp = ip->i_mount;
1658 struct xfs_trans *tp;
1659 int error = 0;
1660
1661 /* Start a rolling transaction to remove the mappings */
1662 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0, 0, &tp);
1663 if (error)
1664 return error;
1665
1666 xfs_ilock(ip, XFS_ILOCK_EXCL);
1667 xfs_trans_ijoin(tp, ip, 0);
1668
1669 error = xfs_reflink_clear_inode_flag(ip, &tp);
1670 if (error)
1671 goto cancel;
1672
1673 error = xfs_trans_commit(tp);
1674 if (error)
1675 goto out;
1676
1677 xfs_iunlock(ip, XFS_ILOCK_EXCL);
1678 return 0;
1679cancel:
1680 xfs_trans_cancel(tp);
1681out:
1682 xfs_iunlock(ip, XFS_ILOCK_EXCL);
1683 return error;
1684}
1685
1686/*
1687 * Pre-COW all shared blocks within a given byte range of a file and turn off
1688 * the reflink flag if we unshare all of the file's blocks.
1689 */
1690int
1691xfs_reflink_unshare(
1692 struct xfs_inode *ip,
1693 xfs_off_t offset,
1694 xfs_off_t len)
1695{
1696 struct inode *inode = VFS_I(ip);
1697 int error;
1698
1699 if (!xfs_is_reflink_inode(ip))
1700 return 0;
1701
1702 trace_xfs_reflink_unshare(ip, offset, len);
1703
1704 inode_dio_wait(inode);
1705
1706 if (IS_DAX(inode))
1707 error = dax_file_unshare(inode, offset, len,
1708 &xfs_dax_write_iomap_ops);
1709 else
1710 error = iomap_file_unshare(inode, offset, len,
1711 &xfs_buffered_write_iomap_ops);
1712 if (error)
1713 goto out;
1714
1715 error = filemap_write_and_wait_range(inode->i_mapping, offset,
1716 offset + len - 1);
1717 if (error)
1718 goto out;
1719
1720 /* Turn off the reflink flag if possible. */
1721 error = xfs_reflink_try_clear_inode_flag(ip);
1722 if (error)
1723 goto out;
1724 return 0;
1725
1726out:
1727 trace_xfs_reflink_unshare_error(ip, error, _RET_IP_);
1728 return error;
1729}