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_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"
19 #include "xfs_bmap.h"
20 #include "xfs_bmap_util.h"
21 #include "xfs_error.h"
22 #include "xfs_dir2.h"
23 #include "xfs_dir2_priv.h"
24 #include "xfs_ioctl.h"
25 #include "xfs_trace.h"
26 #include "xfs_log.h"
27 #include "xfs_icache.h"
28 #include "xfs_pnfs.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"
34 #include "xfs_bit.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"
41 #include "xfs_sb.h"
42 #include "xfs_ag_resv.h"
44 /*
45 * Copy on Write of Shared Blocks
46 *
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.
54 *
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.
59 *
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.
68 *
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.
73 *
74 * D: --RRRRRRSSSRRRRRRRR--- (data fork)
75 * C: ------DDDDDDD--------- (CoW fork)
76 *
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.
82 *
83 * D: --RRRRRRSSSRRRRRRRR---
84 * C: ------UUUUUUU---------
85 *
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.
94 *
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
97 * writes.
98 *
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:
103 *
104 * D: --RRRRRRSSSRRRRRRRR---
105 * C: ------UUrrUUU---------
106 *
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
118 * the CoW fork:
119 *
120 * D: --RRRRRRrrSRRRRRRRR---
121 * C: ------UU--UUU---------
122 *
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
129 * ioend, the better.
130 */
132 /*
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.
138 */
139 int
140 xfs_reflink_find_shared(
141 struct xfs_mount *mp,
142 struct xfs_trans *tp,
143 xfs_agnumber_t agno,
144 xfs_agblock_t agbno,
145 xfs_extlen_t aglen,
146 xfs_agblock_t *fbno,
147 xfs_extlen_t *flen,
148 bool find_end_of_shared)
149 {
150 struct xfs_buf *agbp;
151 struct xfs_btree_cur *cur;
152 int error;
154 error = xfs_alloc_read_agf(mp, tp, agno, 0, &agbp);
155 if (error)
156 return error;
157 if (!agbp)
158 return -ENOMEM;
160 cur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno);
162 error = xfs_refcount_find_shared(cur, agbno, aglen, fbno, flen,
163 find_end_of_shared);
165 xfs_btree_del_cursor(cur, error);
167 xfs_trans_brelse(tp, agbp);
168 return error;
169 }
171 /*
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.
180 */
181 int
182 xfs_reflink_trim_around_shared(
183 struct xfs_inode *ip,
184 struct xfs_bmbt_irec *irec,
185 bool *shared,
186 bool *trimmed)
187 {
188 xfs_agnumber_t agno;
189 xfs_agblock_t agbno;
190 xfs_extlen_t aglen;
191 xfs_agblock_t fbno;
192 xfs_extlen_t flen;
193 int error = 0;
195 /* Holes, unwritten, and delalloc extents cannot be shared */
196 if (!xfs_is_reflink_inode(ip) || !xfs_bmap_is_real_extent(irec)) {
197 *shared = false;
198 return 0;
199 }
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);
209 if (error)
210 return error;
212 *shared = *trimmed = false;
213 if (fbno == NULLAGBLOCK) {
214 /* No shared blocks at all. */
215 return 0;
216 } else if (fbno == agbno) {
217 /*
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
221 * unshared region.
222 */
223 irec->br_blockcount = flen;
224 *shared = true;
225 if (flen != aglen)
226 *trimmed = true;
227 return 0;
228 } else {
229 /*
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.
234 */
235 irec->br_blockcount = fbno - agbno;
236 *trimmed = true;
237 return 0;
238 }
239 }
241 /*
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
244 * COW fork. In this case *shared is set to true, else to false.
245 *
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
248 * operations.
249 */
250 int
251 xfs_reflink_reserve_cow(
252 struct xfs_inode *ip,
253 struct xfs_bmbt_irec *imap,
254 bool *shared)
255 {
256 struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
257 struct xfs_bmbt_irec got;
258 int error = 0;
259 bool eof = false, trimmed;
260 struct xfs_iext_cursor icur;
262 /*
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
268 * tree.
269 */
271 if (!xfs_iext_lookup_extent(ip, ifp, imap->br_startoff, &icur, &got))
272 eof = true;
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);
277 *shared = true;
278 return 0;
279 }
281 /* Trim the mapping to the nearest shared extent boundary. */
282 error = xfs_reflink_trim_around_shared(ip, imap, shared, &trimmed);
283 if (error)
284 return error;
286 /* Not shared? Just report the (potentially capped) extent. */
287 if (!*shared)
288 return 0;
290 /*
291 * Fork all the shared blocks from our write offset until the end of
292 * the extent.
293 */
294 error = xfs_qm_dqattach_locked(ip, false);
295 if (error)
296 return error;
298 error = xfs_bmapi_reserve_delalloc(ip, XFS_COW_FORK, imap->br_startoff,
299 imap->br_blockcount, 0, &got, &icur, eof);
300 if (error == -ENOSPC || error == -EDQUOT)
301 trace_xfs_reflink_cow_enospc(ip, imap);
302 if (error)
303 return error;
305 trace_xfs_reflink_cow_alloc(ip, &got);
306 return 0;
307 }
309 /* Convert part of an unwritten CoW extent to a real one. */
310 STATIC int
311 xfs_reflink_convert_cow_extent(
312 struct xfs_inode *ip,
313 struct xfs_bmbt_irec *imap,
314 xfs_fileoff_t offset_fsb,
315 xfs_filblks_t count_fsb)
316 {
317 int nimaps = 1;
319 if (imap->br_state == XFS_EXT_NORM)
320 return 0;
322 xfs_trim_extent(imap, offset_fsb, count_fsb);
323 trace_xfs_reflink_convert_cow(ip, imap);
324 if (imap->br_blockcount == 0)
325 return 0;
326 return xfs_bmapi_write(NULL, ip, imap->br_startoff, imap->br_blockcount,
327 XFS_BMAPI_COWFORK | XFS_BMAPI_CONVERT, 0, imap,
328 &nimaps);
329 }
331 /* Convert all of the unwritten CoW extents in a file's range to real ones. */
332 int
333 xfs_reflink_convert_cow(
334 struct xfs_inode *ip,
335 xfs_off_t offset,
336 xfs_off_t count)
337 {
338 struct xfs_mount *mp = ip->i_mount;
339 xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset);
340 xfs_fileoff_t end_fsb = XFS_B_TO_FSB(mp, offset + count);
341 xfs_filblks_t count_fsb = end_fsb - offset_fsb;
342 struct xfs_bmbt_irec imap;
343 int nimaps = 1, error = 0;
345 ASSERT(count != 0);
347 xfs_ilock(ip, XFS_ILOCK_EXCL);
348 error = xfs_bmapi_write(NULL, ip, offset_fsb, count_fsb,
349 XFS_BMAPI_COWFORK | XFS_BMAPI_CONVERT |
350 XFS_BMAPI_CONVERT_ONLY, 0, &imap, &nimaps);
351 xfs_iunlock(ip, XFS_ILOCK_EXCL);
352 return error;
353 }
355 /* Allocate all CoW reservations covering a range of blocks in a file. */
356 int
357 xfs_reflink_allocate_cow(
358 struct xfs_inode *ip,
359 struct xfs_bmbt_irec *imap,
360 bool *shared,
361 uint *lockmode)
362 {
363 struct xfs_mount *mp = ip->i_mount;
364 xfs_fileoff_t offset_fsb = imap->br_startoff;
365 xfs_filblks_t count_fsb = imap->br_blockcount;
366 struct xfs_bmbt_irec got;
367 struct xfs_trans *tp = NULL;
368 int nimaps, error = 0;
369 bool trimmed;
370 xfs_filblks_t resaligned;
371 xfs_extlen_t resblks = 0;
372 struct xfs_iext_cursor icur;
374 retry:
375 ASSERT(xfs_is_reflink_inode(ip));
376 ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
378 /*
379 * Even if the extent is not shared we might have a preallocation for
380 * it in the COW fork. If so use it.
381 */
382 if (xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &got) &&
383 got.br_startoff <= offset_fsb) {
384 *shared = true;
386 /* If we have a real allocation in the COW fork we're done. */
387 if (!isnullstartblock(got.br_startblock)) {
388 xfs_trim_extent(&got, offset_fsb, count_fsb);
389 *imap = got;
390 goto convert;
391 }
393 xfs_trim_extent(imap, got.br_startoff, got.br_blockcount);
394 } else {
395 error = xfs_reflink_trim_around_shared(ip, imap, shared, &trimmed);
396 if (error || !*shared)
397 goto out;
398 }
400 if (!tp) {
401 resaligned = xfs_aligned_fsb_count(imap->br_startoff,
402 imap->br_blockcount, xfs_get_cowextsz_hint(ip));
403 resblks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
405 xfs_iunlock(ip, *lockmode);
406 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0, 0, &tp);
407 *lockmode = XFS_ILOCK_EXCL;
408 xfs_ilock(ip, *lockmode);
410 if (error)
411 return error;
413 error = xfs_qm_dqattach_locked(ip, false);
414 if (error)
415 goto out;
416 goto retry;
417 }
419 error = xfs_trans_reserve_quota_nblks(tp, ip, resblks, 0,
420 XFS_QMOPT_RES_REGBLKS);
421 if (error)
422 goto out;
424 xfs_trans_ijoin(tp, ip, 0);
426 nimaps = 1;
428 /* Allocate the entire reservation as unwritten blocks. */
429 error = xfs_bmapi_write(tp, ip, imap->br_startoff, imap->br_blockcount,
430 XFS_BMAPI_COWFORK | XFS_BMAPI_PREALLOC,
431 resblks, imap, &nimaps);
432 if (error)
433 goto out_trans_cancel;
435 xfs_inode_set_cowblocks_tag(ip);
437 /* Finish up. */
438 error = xfs_trans_commit(tp);
439 if (error)
440 return error;
442 /*
443 * Allocation succeeded but the requested range was not even partially
444 * satisfied? Bail out!
445 */
446 if (nimaps == 0)
447 return -ENOSPC;
448 convert:
449 return xfs_reflink_convert_cow_extent(ip, imap, offset_fsb, count_fsb);
450 out_trans_cancel:
451 xfs_trans_unreserve_quota_nblks(tp, ip, (long)resblks, 0,
452 XFS_QMOPT_RES_REGBLKS);
453 out:
454 if (tp)
455 xfs_trans_cancel(tp);
456 return error;
457 }
459 /*
460 * Cancel CoW reservations for some block range of an inode.
461 *
462 * If cancel_real is true this function cancels all COW fork extents for the
463 * inode; if cancel_real is false, real extents are not cleared.
464 *
465 * Caller must have already joined the inode to the current transaction. The
466 * inode will be joined to the transaction returned to the caller.
467 */
468 int
469 xfs_reflink_cancel_cow_blocks(
470 struct xfs_inode *ip,
471 struct xfs_trans **tpp,
472 xfs_fileoff_t offset_fsb,
473 xfs_fileoff_t end_fsb,
474 bool cancel_real)
475 {
476 struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
477 struct xfs_bmbt_irec got, del;
478 struct xfs_iext_cursor icur;
479 int error = 0;
481 if (!xfs_inode_has_cow_data(ip))
482 return 0;
483 if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &icur, &got))
484 return 0;
486 /* Walk backwards until we're out of the I/O range... */
487 while (got.br_startoff + got.br_blockcount > offset_fsb) {
488 del = got;
489 xfs_trim_extent(&del, offset_fsb, end_fsb - offset_fsb);
491 /* Extent delete may have bumped ext forward */
492 if (!del.br_blockcount) {
493 xfs_iext_prev(ifp, &icur);
494 goto next_extent;
495 }
497 trace_xfs_reflink_cancel_cow(ip, &del);
499 if (isnullstartblock(del.br_startblock)) {
500 error = xfs_bmap_del_extent_delay(ip, XFS_COW_FORK,
501 &icur, &got, &del);
502 if (error)
503 break;
504 } else if (del.br_state == XFS_EXT_UNWRITTEN || cancel_real) {
505 ASSERT((*tpp)->t_firstblock == NULLFSBLOCK);
507 /* Free the CoW orphan record. */
508 error = xfs_refcount_free_cow_extent(*tpp,
509 del.br_startblock, del.br_blockcount);
510 if (error)
511 break;
513 xfs_bmap_add_free(*tpp, del.br_startblock,
514 del.br_blockcount, NULL);
516 /* Roll the transaction */
517 error = xfs_defer_finish(tpp);
518 if (error)
519 break;
521 /* Remove the mapping from the CoW fork. */
522 xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
524 /* Remove the quota reservation */
525 error = xfs_trans_reserve_quota_nblks(NULL, ip,
526 -(long)del.br_blockcount, 0,
527 XFS_QMOPT_RES_REGBLKS);
528 if (error)
529 break;
530 } else {
531 /* Didn't do anything, push cursor back. */
532 xfs_iext_prev(ifp, &icur);
533 }
534 next_extent:
535 if (!xfs_iext_get_extent(ifp, &icur, &got))
536 break;
537 }
539 /* clear tag if cow fork is emptied */
540 if (!ifp->if_bytes)
541 xfs_inode_clear_cowblocks_tag(ip);
542 return error;
543 }
545 /*
546 * Cancel CoW reservations for some byte range of an inode.
547 *
548 * If cancel_real is true this function cancels all COW fork extents for the
549 * inode; if cancel_real is false, real extents are not cleared.
550 */
551 int
552 xfs_reflink_cancel_cow_range(
553 struct xfs_inode *ip,
554 xfs_off_t offset,
555 xfs_off_t count,
556 bool cancel_real)
557 {
558 struct xfs_trans *tp;
559 xfs_fileoff_t offset_fsb;
560 xfs_fileoff_t end_fsb;
561 int error;
563 trace_xfs_reflink_cancel_cow_range(ip, offset, count);
564 ASSERT(xfs_is_reflink_inode(ip));
566 offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
567 if (count == NULLFILEOFF)
568 end_fsb = NULLFILEOFF;
569 else
570 end_fsb = XFS_B_TO_FSB(ip->i_mount, offset + count);
572 /* Start a rolling transaction to remove the mappings */
573 error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_write,
574 0, 0, XFS_TRANS_NOFS, &tp);
575 if (error)
576 goto out;
578 xfs_ilock(ip, XFS_ILOCK_EXCL);
579 xfs_trans_ijoin(tp, ip, 0);
581 /* Scrape out the old CoW reservations */
582 error = xfs_reflink_cancel_cow_blocks(ip, &tp, offset_fsb, end_fsb,
583 cancel_real);
584 if (error)
585 goto out_cancel;
587 error = xfs_trans_commit(tp);
589 xfs_iunlock(ip, XFS_ILOCK_EXCL);
590 return error;
592 out_cancel:
593 xfs_trans_cancel(tp);
594 xfs_iunlock(ip, XFS_ILOCK_EXCL);
595 out:
596 trace_xfs_reflink_cancel_cow_range_error(ip, error, _RET_IP_);
597 return error;
598 }
600 /*
601 * Remap parts of a file's data fork after a successful CoW.
602 */
603 int
604 xfs_reflink_end_cow(
605 struct xfs_inode *ip,
606 xfs_off_t offset,
607 xfs_off_t count)
608 {
609 struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
610 struct xfs_bmbt_irec got, del;
611 struct xfs_trans *tp;
612 xfs_fileoff_t offset_fsb;
613 xfs_fileoff_t end_fsb;
614 int error;
615 unsigned int resblks;
616 xfs_filblks_t rlen;
617 struct xfs_iext_cursor icur;
619 trace_xfs_reflink_end_cow(ip, offset, count);
621 /* No COW extents? That's easy! */
622 if (ifp->if_bytes == 0)
623 return 0;
625 offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
626 end_fsb = XFS_B_TO_FSB(ip->i_mount, offset + count);
628 /*
629 * Start a rolling transaction to switch the mappings. We're
630 * unlikely ever to have to remap 16T worth of single-block
631 * extents, so just cap the worst case extent count to 2^32-1.
632 * Stick a warning in just in case, and avoid 64-bit division.
633 */
634 BUILD_BUG_ON(MAX_RW_COUNT > UINT_MAX);
635 if (end_fsb - offset_fsb > UINT_MAX) {
636 error = -EFSCORRUPTED;
637 xfs_force_shutdown(ip->i_mount, SHUTDOWN_CORRUPT_INCORE);
638 ASSERT(0);
639 goto out;
640 }
641 resblks = XFS_NEXTENTADD_SPACE_RES(ip->i_mount,
642 (unsigned int)(end_fsb - offset_fsb),
643 XFS_DATA_FORK);
644 error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_write,
645 resblks, 0, XFS_TRANS_RESERVE | XFS_TRANS_NOFS, &tp);
646 if (error)
647 goto out;
649 xfs_ilock(ip, XFS_ILOCK_EXCL);
650 xfs_trans_ijoin(tp, ip, 0);
652 /*
653 * In case of racing, overlapping AIO writes no COW extents might be
654 * left by the time I/O completes for the loser of the race. In that
655 * case we are done.
656 */
657 if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &icur, &got))
658 goto out_cancel;
660 /* Walk backwards until we're out of the I/O range... */
661 while (got.br_startoff + got.br_blockcount > offset_fsb) {
662 del = got;
663 xfs_trim_extent(&del, offset_fsb, end_fsb - offset_fsb);
665 /* Extent delete may have bumped ext forward */
666 if (!del.br_blockcount)
667 goto prev_extent;
669 ASSERT(!isnullstartblock(got.br_startblock));
671 /*
672 * Don't remap unwritten extents; these are
673 * speculatively preallocated CoW extents that have been
674 * allocated but have not yet been involved in a write.
675 */
676 if (got.br_state == XFS_EXT_UNWRITTEN)
677 goto prev_extent;
679 /* Unmap the old blocks in the data fork. */
680 ASSERT(tp->t_firstblock == NULLFSBLOCK);
681 rlen = del.br_blockcount;
682 error = __xfs_bunmapi(tp, ip, del.br_startoff, &rlen, 0, 1);
683 if (error)
684 goto out_cancel;
686 /* Trim the extent to whatever got unmapped. */
687 if (rlen) {
688 xfs_trim_extent(&del, del.br_startoff + rlen,
689 del.br_blockcount - rlen);
690 }
691 trace_xfs_reflink_cow_remap(ip, &del);
693 /* Free the CoW orphan record. */
694 error = xfs_refcount_free_cow_extent(tp, del.br_startblock,
695 del.br_blockcount);
696 if (error)
697 goto out_cancel;
699 /* Map the new blocks into the data fork. */
700 error = xfs_bmap_map_extent(tp, ip, &del);
701 if (error)
702 goto out_cancel;
704 /* Charge this new data fork mapping to the on-disk quota. */
705 xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_DELBCOUNT,
706 (long)del.br_blockcount);
708 /* Remove the mapping from the CoW fork. */
709 xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
711 error = xfs_defer_finish(&tp);
712 if (error)
713 goto out_cancel;
714 if (!xfs_iext_get_extent(ifp, &icur, &got))
715 break;
716 continue;
717 prev_extent:
718 if (!xfs_iext_prev_extent(ifp, &icur, &got))
719 break;
720 }
722 error = xfs_trans_commit(tp);
723 xfs_iunlock(ip, XFS_ILOCK_EXCL);
724 if (error)
725 goto out;
726 return 0;
728 out_cancel:
729 xfs_trans_cancel(tp);
730 xfs_iunlock(ip, XFS_ILOCK_EXCL);
731 out:
732 trace_xfs_reflink_end_cow_error(ip, error, _RET_IP_);
733 return error;
734 }
736 /*
737 * Free leftover CoW reservations that didn't get cleaned out.
738 */
739 int
740 xfs_reflink_recover_cow(
741 struct xfs_mount *mp)
742 {
743 xfs_agnumber_t agno;
744 int error = 0;
746 if (!xfs_sb_version_hasreflink(&mp->m_sb))
747 return 0;
749 for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
750 error = xfs_refcount_recover_cow_leftovers(mp, agno);
751 if (error)
752 break;
753 }
755 return error;
756 }
758 /*
759 * Reflinking (Block) Ranges of Two Files Together
760 *
761 * First, ensure that the reflink flag is set on both inodes. The flag is an
762 * optimization to avoid unnecessary refcount btree lookups in the write path.
763 *
764 * Now we can iteratively remap the range of extents (and holes) in src to the
765 * corresponding ranges in dest. Let drange and srange denote the ranges of
766 * logical blocks in dest and src touched by the reflink operation.
767 *
768 * While the length of drange is greater than zero,
769 * - Read src's bmbt at the start of srange ("imap")
770 * - If imap doesn't exist, make imap appear to start at the end of srange
771 * with zero length.
772 * - If imap starts before srange, advance imap to start at srange.
773 * - If imap goes beyond srange, truncate imap to end at the end of srange.
774 * - Punch (imap start - srange start + imap len) blocks from dest at
775 * offset (drange start).
776 * - If imap points to a real range of pblks,
777 * > Increase the refcount of the imap's pblks
778 * > Map imap's pblks into dest at the offset
779 * (drange start + imap start - srange start)
780 * - Advance drange and srange by (imap start - srange start + imap len)
781 *
782 * Finally, if the reflink made dest longer, update both the in-core and
783 * on-disk file sizes.
784 *
785 * ASCII Art Demonstration:
786 *
787 * Let's say we want to reflink this source file:
788 *
789 * ----SSSSSSS-SSSSS----SSSSSS (src file)
790 * <-------------------->
791 *
792 * into this destination file:
793 *
794 * --DDDDDDDDDDDDDDDDDDD--DDD (dest file)
795 * <-------------------->
796 * '-' means a hole, and 'S' and 'D' are written blocks in the src and dest.
797 * Observe that the range has different logical offsets in either file.
798 *
799 * Consider that the first extent in the source file doesn't line up with our
800 * reflink range. Unmapping and remapping are separate operations, so we can
801 * unmap more blocks from the destination file than we remap.
802 *
803 * ----SSSSSSS-SSSSS----SSSSSS
804 * <------->
805 * --DDDDD---------DDDDD--DDD
806 * <------->
807 *
808 * Now remap the source extent into the destination file:
809 *
810 * ----SSSSSSS-SSSSS----SSSSSS
811 * <------->
812 * --DDDDD--SSSSSSSDDDDD--DDD
813 * <------->
814 *
815 * Do likewise with the second hole and extent in our range. Holes in the
816 * unmap range don't affect our operation.
817 *
818 * ----SSSSSSS-SSSSS----SSSSSS
819 * <---->
820 * --DDDDD--SSSSSSS-SSSSS-DDD
821 * <---->
822 *
823 * Finally, unmap and remap part of the third extent. This will increase the
824 * size of the destination file.
825 *
826 * ----SSSSSSS-SSSSS----SSSSSS
827 * <----->
828 * --DDDDD--SSSSSSS-SSSSS----SSS
829 * <----->
830 *
831 * Once we update the destination file's i_size, we're done.
832 */
834 /*
835 * Ensure the reflink bit is set in both inodes.
836 */
837 STATIC int
838 xfs_reflink_set_inode_flag(
839 struct xfs_inode *src,
840 struct xfs_inode *dest)
841 {
842 struct xfs_mount *mp = src->i_mount;
843 int error;
844 struct xfs_trans *tp;
846 if (xfs_is_reflink_inode(src) && xfs_is_reflink_inode(dest))
847 return 0;
849 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
850 if (error)
851 goto out_error;
853 /* Lock both files against IO */
854 if (src->i_ino == dest->i_ino)
855 xfs_ilock(src, XFS_ILOCK_EXCL);
856 else
857 xfs_lock_two_inodes(src, XFS_ILOCK_EXCL, dest, XFS_ILOCK_EXCL);
859 if (!xfs_is_reflink_inode(src)) {
860 trace_xfs_reflink_set_inode_flag(src);
861 xfs_trans_ijoin(tp, src, XFS_ILOCK_EXCL);
862 src->i_d.di_flags2 |= XFS_DIFLAG2_REFLINK;
863 xfs_trans_log_inode(tp, src, XFS_ILOG_CORE);
864 xfs_ifork_init_cow(src);
865 } else
866 xfs_iunlock(src, XFS_ILOCK_EXCL);
868 if (src->i_ino == dest->i_ino)
869 goto commit_flags;
871 if (!xfs_is_reflink_inode(dest)) {
872 trace_xfs_reflink_set_inode_flag(dest);
873 xfs_trans_ijoin(tp, dest, XFS_ILOCK_EXCL);
874 dest->i_d.di_flags2 |= XFS_DIFLAG2_REFLINK;
875 xfs_trans_log_inode(tp, dest, XFS_ILOG_CORE);
876 xfs_ifork_init_cow(dest);
877 } else
878 xfs_iunlock(dest, XFS_ILOCK_EXCL);
880 commit_flags:
881 error = xfs_trans_commit(tp);
882 if (error)
883 goto out_error;
884 return error;
886 out_error:
887 trace_xfs_reflink_set_inode_flag_error(dest, error, _RET_IP_);
888 return error;
889 }
891 /*
892 * Update destination inode size & cowextsize hint, if necessary.
893 */
894 STATIC int
895 xfs_reflink_update_dest(
896 struct xfs_inode *dest,
897 xfs_off_t newlen,
898 xfs_extlen_t cowextsize,
899 bool is_dedupe)
900 {
901 struct xfs_mount *mp = dest->i_mount;
902 struct xfs_trans *tp;
903 int error;
905 if (is_dedupe && newlen <= i_size_read(VFS_I(dest)) && cowextsize == 0)
906 return 0;
908 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
909 if (error)
910 goto out_error;
912 xfs_ilock(dest, XFS_ILOCK_EXCL);
913 xfs_trans_ijoin(tp, dest, XFS_ILOCK_EXCL);
915 if (newlen > i_size_read(VFS_I(dest))) {
916 trace_xfs_reflink_update_inode_size(dest, newlen);
917 i_size_write(VFS_I(dest), newlen);
918 dest->i_d.di_size = newlen;
919 }
921 if (cowextsize) {
922 dest->i_d.di_cowextsize = cowextsize;
923 dest->i_d.di_flags2 |= XFS_DIFLAG2_COWEXTSIZE;
924 }
926 if (!is_dedupe) {
927 xfs_trans_ichgtime(tp, dest,
928 XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
929 }
930 xfs_trans_log_inode(tp, dest, XFS_ILOG_CORE);
932 error = xfs_trans_commit(tp);
933 if (error)
934 goto out_error;
935 return error;
937 out_error:
938 trace_xfs_reflink_update_inode_size_error(dest, error, _RET_IP_);
939 return error;
940 }
942 /*
943 * Do we have enough reserve in this AG to handle a reflink? The refcount
944 * btree already reserved all the space it needs, but the rmap btree can grow
945 * infinitely, so we won't allow more reflinks when the AG is down to the
946 * btree reserves.
947 */
948 static int
949 xfs_reflink_ag_has_free_space(
950 struct xfs_mount *mp,
951 xfs_agnumber_t agno)
952 {
953 struct xfs_perag *pag;
954 int error = 0;
956 if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
957 return 0;
959 pag = xfs_perag_get(mp, agno);
960 if (xfs_ag_resv_critical(pag, XFS_AG_RESV_RMAPBT) ||
961 xfs_ag_resv_critical(pag, XFS_AG_RESV_METADATA))
962 error = -ENOSPC;
963 xfs_perag_put(pag);
964 return error;
965 }
967 /*
968 * Unmap a range of blocks from a file, then map other blocks into the hole.
969 * The range to unmap is (destoff : destoff + srcioff + irec->br_blockcount).
970 * The extent irec is mapped into dest at irec->br_startoff.
971 */
972 STATIC int
973 xfs_reflink_remap_extent(
974 struct xfs_inode *ip,
975 struct xfs_bmbt_irec *irec,
976 xfs_fileoff_t destoff,
977 xfs_off_t new_isize)
978 {
979 struct xfs_mount *mp = ip->i_mount;
980 bool real_extent = xfs_bmap_is_real_extent(irec);
981 struct xfs_trans *tp;
982 unsigned int resblks;
983 struct xfs_bmbt_irec uirec;
984 xfs_filblks_t rlen;
985 xfs_filblks_t unmap_len;
986 xfs_off_t newlen;
987 int error;
989 unmap_len = irec->br_startoff + irec->br_blockcount - destoff;
990 trace_xfs_reflink_punch_range(ip, destoff, unmap_len);
992 /* No reflinking if we're low on space */
993 if (real_extent) {
994 error = xfs_reflink_ag_has_free_space(mp,
995 XFS_FSB_TO_AGNO(mp, irec->br_startblock));
996 if (error)
997 goto out;
998 }
1000 /* Start a rolling transaction to switch the mappings */
1001 resblks = XFS_EXTENTADD_SPACE_RES(ip->i_mount, XFS_DATA_FORK);
1002 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0, 0, &tp);
1003 if (error)
1004 goto out;
1006 xfs_ilock(ip, XFS_ILOCK_EXCL);
1007 xfs_trans_ijoin(tp, ip, 0);
1009 /* If we're not just clearing space, then do we have enough quota? */
1010 if (real_extent) {
1011 error = xfs_trans_reserve_quota_nblks(tp, ip,
1012 irec->br_blockcount, 0, XFS_QMOPT_RES_REGBLKS);
1013 if (error)
1014 goto out_cancel;
1015 }
1017 trace_xfs_reflink_remap(ip, irec->br_startoff,
1018 irec->br_blockcount, irec->br_startblock);
1020 /* Unmap the old blocks in the data fork. */
1021 rlen = unmap_len;
1022 while (rlen) {
1023 ASSERT(tp->t_firstblock == NULLFSBLOCK);
1024 error = __xfs_bunmapi(tp, ip, destoff, &rlen, 0, 1);
1025 if (error)
1026 goto out_cancel;
1028 /*
1029 * Trim the extent to whatever got unmapped.
1030 * Remember, bunmapi works backwards.
1031 */
1032 uirec.br_startblock = irec->br_startblock + rlen;
1033 uirec.br_startoff = irec->br_startoff + rlen;
1034 uirec.br_blockcount = unmap_len - rlen;
1035 unmap_len = rlen;
1037 /* If this isn't a real mapping, we're done. */
1038 if (!real_extent || uirec.br_blockcount == 0)
1039 goto next_extent;
1041 trace_xfs_reflink_remap(ip, uirec.br_startoff,
1042 uirec.br_blockcount, uirec.br_startblock);
1044 /* Update the refcount tree */
1045 error = xfs_refcount_increase_extent(tp, &uirec);
1046 if (error)
1047 goto out_cancel;
1049 /* Map the new blocks into the data fork. */
1050 error = xfs_bmap_map_extent(tp, ip, &uirec);
1051 if (error)
1052 goto out_cancel;
1054 /* Update quota accounting. */
1055 xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT,
1056 uirec.br_blockcount);
1058 /* Update dest isize if needed. */
1059 newlen = XFS_FSB_TO_B(mp,
1060 uirec.br_startoff + uirec.br_blockcount);
1061 newlen = min_t(xfs_off_t, newlen, new_isize);
1062 if (newlen > i_size_read(VFS_I(ip))) {
1063 trace_xfs_reflink_update_inode_size(ip, newlen);
1064 i_size_write(VFS_I(ip), newlen);
1065 ip->i_d.di_size = newlen;
1066 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
1067 }
1069 next_extent:
1070 /* Process all the deferred stuff. */
1071 error = xfs_defer_finish(&tp);
1072 if (error)
1073 goto out_cancel;
1074 }
1076 error = xfs_trans_commit(tp);
1077 xfs_iunlock(ip, XFS_ILOCK_EXCL);
1078 if (error)
1079 goto out;
1080 return 0;
1082 out_cancel:
1083 xfs_trans_cancel(tp);
1084 xfs_iunlock(ip, XFS_ILOCK_EXCL);
1085 out:
1086 trace_xfs_reflink_remap_extent_error(ip, error, _RET_IP_);
1087 return error;
1088 }
1090 /*
1091 * Iteratively remap one file's extents (and holes) to another's.
1092 */
1093 STATIC int
1094 xfs_reflink_remap_blocks(
1095 struct xfs_inode *src,
1096 xfs_fileoff_t srcoff,
1097 struct xfs_inode *dest,
1098 xfs_fileoff_t destoff,
1099 xfs_filblks_t len,
1100 xfs_off_t new_isize)
1101 {
1102 struct xfs_bmbt_irec imap;
1103 int nimaps;
1104 int error = 0;
1105 xfs_filblks_t range_len;
1107 /* drange = (destoff, destoff + len); srange = (srcoff, srcoff + len) */
1108 while (len) {
1109 uint lock_mode;
1111 trace_xfs_reflink_remap_blocks_loop(src, srcoff, len,
1112 dest, destoff);
1114 /* Read extent from the source file */
1115 nimaps = 1;
1116 lock_mode = xfs_ilock_data_map_shared(src);
1117 error = xfs_bmapi_read(src, srcoff, len, &imap, &nimaps, 0);
1118 xfs_iunlock(src, lock_mode);
1119 if (error)
1120 goto err;
1121 ASSERT(nimaps == 1);
1123 trace_xfs_reflink_remap_imap(src, srcoff, len, XFS_IO_OVERWRITE,
1124 &imap);
1126 /* Translate imap into the destination file. */
1127 range_len = imap.br_startoff + imap.br_blockcount - srcoff;
1128 imap.br_startoff += destoff - srcoff;
1130 /* Clear dest from destoff to the end of imap and map it in. */
1131 error = xfs_reflink_remap_extent(dest, &imap, destoff,
1132 new_isize);
1133 if (error)
1134 goto err;
1136 if (fatal_signal_pending(current)) {
1137 error = -EINTR;
1138 goto err;
1139 }
1141 /* Advance drange/srange */
1142 srcoff += range_len;
1143 destoff += range_len;
1144 len -= range_len;
1145 }
1147 return 0;
1149 err:
1150 trace_xfs_reflink_remap_blocks_error(dest, error, _RET_IP_);
1151 return error;
1152 }
1154 /*
1155 * Grab the exclusive iolock for a data copy from src to dest, making
1156 * sure to abide vfs locking order (lowest pointer value goes first) and
1157 * breaking the pnfs layout leases on dest before proceeding. The loop
1158 * is needed because we cannot call the blocking break_layout() with the
1159 * src iolock held, and therefore have to back out both locks.
1160 */
1161 static int
1162 xfs_iolock_two_inodes_and_break_layout(
1163 struct inode *src,
1164 struct inode *dest)
1165 {
1166 int error;
1168 retry:
1169 if (src < dest) {
1170 inode_lock_shared(src);
1171 inode_lock_nested(dest, I_MUTEX_NONDIR2);
1172 } else {
1173 /* src >= dest */
1174 inode_lock(dest);
1175 }
1177 error = break_layout(dest, false);
1178 if (error == -EWOULDBLOCK) {
1179 inode_unlock(dest);
1180 if (src < dest)
1181 inode_unlock_shared(src);
1182 error = break_layout(dest, true);
1183 if (error)
1184 return error;
1185 goto retry;
1186 }
1187 if (error) {
1188 inode_unlock(dest);
1189 if (src < dest)
1190 inode_unlock_shared(src);
1191 return error;
1192 }
1193 if (src > dest)
1194 inode_lock_shared_nested(src, I_MUTEX_NONDIR2);
1195 return 0;
1196 }
1198 /*
1199 * Link a range of blocks from one file to another.
1200 */
1201 int
1202 xfs_reflink_remap_range(
1203 struct file *file_in,
1204 loff_t pos_in,
1205 struct file *file_out,
1206 loff_t pos_out,
1207 u64 len,
1208 bool is_dedupe)
1209 {
1210 struct inode *inode_in = file_inode(file_in);
1211 struct xfs_inode *src = XFS_I(inode_in);
1212 struct inode *inode_out = file_inode(file_out);
1213 struct xfs_inode *dest = XFS_I(inode_out);
1214 struct xfs_mount *mp = src->i_mount;
1215 bool same_inode = (inode_in == inode_out);
1216 xfs_fileoff_t sfsbno, dfsbno;
1217 xfs_filblks_t fsblen;
1218 xfs_extlen_t cowextsize;
1219 ssize_t ret;
1221 if (!xfs_sb_version_hasreflink(&mp->m_sb))
1222 return -EOPNOTSUPP;
1224 if (XFS_FORCED_SHUTDOWN(mp))
1225 return -EIO;
1227 /* Lock both files against IO */
1228 ret = xfs_iolock_two_inodes_and_break_layout(inode_in, inode_out);
1229 if (ret)
1230 return ret;
1231 if (same_inode)
1232 xfs_ilock(src, XFS_MMAPLOCK_EXCL);
1233 else
1234 xfs_lock_two_inodes(src, XFS_MMAPLOCK_SHARED, dest,
1235 XFS_MMAPLOCK_EXCL);
1237 /* Check file eligibility and prepare for block sharing. */
1238 ret = -EINVAL;
1239 /* Don't reflink realtime inodes */
1240 if (XFS_IS_REALTIME_INODE(src) || XFS_IS_REALTIME_INODE(dest))
1241 goto out_unlock;
1243 /* Don't share DAX file data for now. */
1244 if (IS_DAX(inode_in) || IS_DAX(inode_out))
1245 goto out_unlock;
1247 ret = vfs_clone_file_prep_inodes(inode_in, pos_in, inode_out, pos_out,
1248 &len, is_dedupe);
1249 if (ret <= 0)
1250 goto out_unlock;
1252 /* Attach dquots to dest inode before changing block map */
1253 ret = xfs_qm_dqattach(dest);
1254 if (ret)
1255 goto out_unlock;
1257 trace_xfs_reflink_remap_range(src, pos_in, len, dest, pos_out);
1259 /*
1260 * Clear out post-eof preallocations because we don't have page cache
1261 * backing the delayed allocations and they'll never get freed on
1262 * their own.
1263 */
1264 if (xfs_can_free_eofblocks(dest, true)) {
1265 ret = xfs_free_eofblocks(dest);
1266 if (ret)
1267 goto out_unlock;
1268 }
1270 /* Set flags and remap blocks. */
1271 ret = xfs_reflink_set_inode_flag(src, dest);
1272 if (ret)
1273 goto out_unlock;
1275 dfsbno = XFS_B_TO_FSBT(mp, pos_out);
1276 sfsbno = XFS_B_TO_FSBT(mp, pos_in);
1277 fsblen = XFS_B_TO_FSB(mp, len);
1278 ret = xfs_reflink_remap_blocks(src, sfsbno, dest, dfsbno, fsblen,
1279 pos_out + len);
1280 if (ret)
1281 goto out_unlock;
1283 /* Zap any page cache for the destination file's range. */
1284 truncate_inode_pages_range(&inode_out->i_data, pos_out,
1285 PAGE_ALIGN(pos_out + len) - 1);
1287 /*
1288 * Carry the cowextsize hint from src to dest if we're sharing the
1289 * entire source file to the entire destination file, the source file
1290 * has a cowextsize hint, and the destination file does not.
1291 */
1292 cowextsize = 0;
1293 if (pos_in == 0 && len == i_size_read(inode_in) &&
1294 (src->i_d.di_flags2 & XFS_DIFLAG2_COWEXTSIZE) &&
1295 pos_out == 0 && len >= i_size_read(inode_out) &&
1296 !(dest->i_d.di_flags2 & XFS_DIFLAG2_COWEXTSIZE))
1297 cowextsize = src->i_d.di_cowextsize;
1299 ret = xfs_reflink_update_dest(dest, pos_out + len, cowextsize,
1300 is_dedupe);
1302 out_unlock:
1303 xfs_iunlock(dest, XFS_MMAPLOCK_EXCL);
1304 if (!same_inode)
1305 xfs_iunlock(src, XFS_MMAPLOCK_SHARED);
1306 inode_unlock(inode_out);
1307 if (!same_inode)
1308 inode_unlock_shared(inode_in);
1309 if (ret)
1310 trace_xfs_reflink_remap_range_error(dest, ret, _RET_IP_);
1311 return ret;
1312 }
1314 /*
1315 * The user wants to preemptively CoW all shared blocks in this file,
1316 * which enables us to turn off the reflink flag. Iterate all
1317 * extents which are not prealloc/delalloc to see which ranges are
1318 * mentioned in the refcount tree, then read those blocks into the
1319 * pagecache, dirty them, fsync them back out, and then we can update
1320 * the inode flag. What happens if we run out of memory? :)
1321 */
1322 STATIC int
1323 xfs_reflink_dirty_extents(
1324 struct xfs_inode *ip,
1325 xfs_fileoff_t fbno,
1326 xfs_filblks_t end,
1327 xfs_off_t isize)
1328 {
1329 struct xfs_mount *mp = ip->i_mount;
1330 xfs_agnumber_t agno;
1331 xfs_agblock_t agbno;
1332 xfs_extlen_t aglen;
1333 xfs_agblock_t rbno;
1334 xfs_extlen_t rlen;
1335 xfs_off_t fpos;
1336 xfs_off_t flen;
1337 struct xfs_bmbt_irec map[2];
1338 int nmaps;
1339 int error = 0;
1341 while (end - fbno > 0) {
1342 nmaps = 1;
1343 /*
1344 * Look for extents in the file. Skip holes, delalloc, or
1345 * unwritten extents; they can't be reflinked.
1346 */
1347 error = xfs_bmapi_read(ip, fbno, end - fbno, map, &nmaps, 0);
1348 if (error)
1349 goto out;
1350 if (nmaps == 0)
1351 break;
1352 if (!xfs_bmap_is_real_extent(&map[0]))
1353 goto next;
1355 map[1] = map[0];
1356 while (map[1].br_blockcount) {
1357 agno = XFS_FSB_TO_AGNO(mp, map[1].br_startblock);
1358 agbno = XFS_FSB_TO_AGBNO(mp, map[1].br_startblock);
1359 aglen = map[1].br_blockcount;
1361 error = xfs_reflink_find_shared(mp, NULL, agno, agbno,
1362 aglen, &rbno, &rlen, true);
1363 if (error)
1364 goto out;
1365 if (rbno == NULLAGBLOCK)
1366 break;
1368 /* Dirty the pages */
1369 xfs_iunlock(ip, XFS_ILOCK_EXCL);
1370 fpos = XFS_FSB_TO_B(mp, map[1].br_startoff +
1371 (rbno - agbno));
1372 flen = XFS_FSB_TO_B(mp, rlen);
1373 if (fpos + flen > isize)
1374 flen = isize - fpos;
1375 error = iomap_file_dirty(VFS_I(ip), fpos, flen,
1376 &xfs_iomap_ops);
1377 xfs_ilock(ip, XFS_ILOCK_EXCL);
1378 if (error)
1379 goto out;
1381 map[1].br_blockcount -= (rbno - agbno + rlen);
1382 map[1].br_startoff += (rbno - agbno + rlen);
1383 map[1].br_startblock += (rbno - agbno + rlen);
1384 }
1386 next:
1387 fbno = map[0].br_startoff + map[0].br_blockcount;
1388 }
1389 out:
1390 return error;
1391 }
1393 /* Does this inode need the reflink flag? */
1394 int
1395 xfs_reflink_inode_has_shared_extents(
1396 struct xfs_trans *tp,
1397 struct xfs_inode *ip,
1398 bool *has_shared)
1399 {
1400 struct xfs_bmbt_irec got;
1401 struct xfs_mount *mp = ip->i_mount;
1402 struct xfs_ifork *ifp;
1403 xfs_agnumber_t agno;
1404 xfs_agblock_t agbno;
1405 xfs_extlen_t aglen;
1406 xfs_agblock_t rbno;
1407 xfs_extlen_t rlen;
1408 struct xfs_iext_cursor icur;
1409 bool found;
1410 int error;
1412 ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
1413 if (!(ifp->if_flags & XFS_IFEXTENTS)) {
1414 error = xfs_iread_extents(tp, ip, XFS_DATA_FORK);
1415 if (error)
1416 return error;
1417 }
1419 *has_shared = false;
1420 found = xfs_iext_lookup_extent(ip, ifp, 0, &icur, &got);
1421 while (found) {
1422 if (isnullstartblock(got.br_startblock) ||
1423 got.br_state != XFS_EXT_NORM)
1424 goto next;
1425 agno = XFS_FSB_TO_AGNO(mp, got.br_startblock);
1426 agbno = XFS_FSB_TO_AGBNO(mp, got.br_startblock);
1427 aglen = got.br_blockcount;
1429 error = xfs_reflink_find_shared(mp, tp, agno, agbno, aglen,
1430 &rbno, &rlen, false);
1431 if (error)
1432 return error;
1433 /* Is there still a shared block here? */
1434 if (rbno != NULLAGBLOCK) {
1435 *has_shared = true;
1436 return 0;
1437 }
1438 next:
1439 found = xfs_iext_next_extent(ifp, &icur, &got);
1440 }
1442 return 0;
1443 }
1445 /*
1446 * Clear the inode reflink flag if there are no shared extents.
1447 *
1448 * The caller is responsible for joining the inode to the transaction passed in.
1449 * The inode will be joined to the transaction that is returned to the caller.
1450 */
1451 int
1452 xfs_reflink_clear_inode_flag(
1453 struct xfs_inode *ip,
1454 struct xfs_trans **tpp)
1455 {
1456 bool needs_flag;
1457 int error = 0;
1459 ASSERT(xfs_is_reflink_inode(ip));
1461 error = xfs_reflink_inode_has_shared_extents(*tpp, ip, &needs_flag);
1462 if (error || needs_flag)
1463 return error;
1465 /*
1466 * We didn't find any shared blocks so turn off the reflink flag.
1467 * First, get rid of any leftover CoW mappings.
1468 */
1469 error = xfs_reflink_cancel_cow_blocks(ip, tpp, 0, NULLFILEOFF, true);
1470 if (error)
1471 return error;
1473 /* Clear the inode flag. */
1474 trace_xfs_reflink_unset_inode_flag(ip);
1475 ip->i_d.di_flags2 &= ~XFS_DIFLAG2_REFLINK;
1476 xfs_inode_clear_cowblocks_tag(ip);
1477 xfs_trans_log_inode(*tpp, ip, XFS_ILOG_CORE);
1479 return error;
1480 }
1482 /*
1483 * Clear the inode reflink flag if there are no shared extents and the size
1484 * hasn't changed.
1485 */
1486 STATIC int
1487 xfs_reflink_try_clear_inode_flag(
1488 struct xfs_inode *ip)
1489 {
1490 struct xfs_mount *mp = ip->i_mount;
1491 struct xfs_trans *tp;
1492 int error = 0;
1494 /* Start a rolling transaction to remove the mappings */
1495 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0, 0, &tp);
1496 if (error)
1497 return error;
1499 xfs_ilock(ip, XFS_ILOCK_EXCL);
1500 xfs_trans_ijoin(tp, ip, 0);
1502 error = xfs_reflink_clear_inode_flag(ip, &tp);
1503 if (error)
1504 goto cancel;
1506 error = xfs_trans_commit(tp);
1507 if (error)
1508 goto out;
1510 xfs_iunlock(ip, XFS_ILOCK_EXCL);
1511 return 0;
1512 cancel:
1513 xfs_trans_cancel(tp);
1514 out:
1515 xfs_iunlock(ip, XFS_ILOCK_EXCL);
1516 return error;
1517 }
1519 /*
1520 * Pre-COW all shared blocks within a given byte range of a file and turn off
1521 * the reflink flag if we unshare all of the file's blocks.
1522 */
1523 int
1524 xfs_reflink_unshare(
1525 struct xfs_inode *ip,
1526 xfs_off_t offset,
1527 xfs_off_t len)
1528 {
1529 struct xfs_mount *mp = ip->i_mount;
1530 xfs_fileoff_t fbno;
1531 xfs_filblks_t end;
1532 xfs_off_t isize;
1533 int error;
1535 if (!xfs_is_reflink_inode(ip))
1536 return 0;
1538 trace_xfs_reflink_unshare(ip, offset, len);
1540 inode_dio_wait(VFS_I(ip));
1542 /* Try to CoW the selected ranges */
1543 xfs_ilock(ip, XFS_ILOCK_EXCL);
1544 fbno = XFS_B_TO_FSBT(mp, offset);
1545 isize = i_size_read(VFS_I(ip));
1546 end = XFS_B_TO_FSB(mp, offset + len);
1547 error = xfs_reflink_dirty_extents(ip, fbno, end, isize);
1548 if (error)
1549 goto out_unlock;
1550 xfs_iunlock(ip, XFS_ILOCK_EXCL);
1552 /* Wait for the IO to finish */
1553 error = filemap_write_and_wait(VFS_I(ip)->i_mapping);
1554 if (error)
1555 goto out;
1557 /* Turn off the reflink flag if possible. */
1558 error = xfs_reflink_try_clear_inode_flag(ip);
1559 if (error)
1560 goto out;
1562 return 0;
1564 out_unlock:
1565 xfs_iunlock(ip, XFS_ILOCK_EXCL);
1566 out:
1567 trace_xfs_reflink_unshare_error(ip, error, _RET_IP_);
1568 return error;
1569 }