Line data Source code
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 :
33 : /*
34 : * Copy on Write of Shared Blocks
35 : *
36 : * XFS must preserve "the usual" file semantics even when two files share
37 : * the same physical blocks. This means that a write to one file must not
38 : * alter the blocks in a different file; the way that we'll do that is
39 : * through the use of a copy-on-write mechanism. At a high level, that
40 : * means that when we want to write to a shared block, we allocate a new
41 : * block, write the data to the new block, and if that succeeds we map the
42 : * new block into the file.
43 : *
44 : * XFS provides a "delayed allocation" mechanism that defers the allocation
45 : * of disk blocks to dirty-but-not-yet-mapped file blocks as long as
46 : * possible. This reduces fragmentation by enabling the filesystem to ask
47 : * for bigger chunks less often, which is exactly what we want for CoW.
48 : *
49 : * The delalloc mechanism begins when the kernel wants to make a block
50 : * writable (write_begin or page_mkwrite). If the offset is not mapped, we
51 : * create a delalloc mapping, which is a regular in-core extent, but without
52 : * a real startblock. (For delalloc mappings, the startblock encodes both
53 : * a flag that this is a delalloc mapping, and a worst-case estimate of how
54 : * many blocks might be required to put the mapping into the BMBT.) delalloc
55 : * mappings are a reservation against the free space in the filesystem;
56 : * adjacent mappings can also be combined into fewer larger mappings.
57 : *
58 : * As an optimization, the CoW extent size hint (cowextsz) creates
59 : * outsized aligned delalloc reservations in the hope of landing out of
60 : * order nearby CoW writes in a single extent on disk, thereby reducing
61 : * fragmentation and improving future performance.
62 : *
63 : * D: --RRRRRRSSSRRRRRRRR--- (data fork)
64 : * C: ------DDDDDDD--------- (CoW fork)
65 : *
66 : * When dirty pages are being written out (typically in writepage), the
67 : * delalloc reservations are converted into unwritten mappings by
68 : * allocating blocks and replacing the delalloc mapping with real ones.
69 : * A delalloc mapping can be replaced by several unwritten ones if the
70 : * free space is fragmented.
71 : *
72 : * D: --RRRRRRSSSRRRRRRRR---
73 : * C: ------UUUUUUU---------
74 : *
75 : * We want to adapt the delalloc mechanism for copy-on-write, since the
76 : * write paths are similar. The first two steps (creating the reservation
77 : * and allocating the blocks) are exactly the same as delalloc except that
78 : * the mappings must be stored in a separate CoW fork because we do not want
79 : * to disturb the mapping in the data fork until we're sure that the write
80 : * succeeded. IO completion in this case is the process of removing the old
81 : * mapping from the data fork and moving the new mapping from the CoW fork to
82 : * the data fork. This will be discussed shortly.
83 : *
84 : * For now, unaligned directio writes will be bounced back to the page cache.
85 : * Block-aligned directio writes will use the same mechanism as buffered
86 : * writes.
87 : *
88 : * Just prior to submitting the actual disk write requests, we convert
89 : * the extents representing the range of the file actually being written
90 : * (as opposed to extra pieces created for the cowextsize hint) to real
91 : * extents. This will become important in the next step:
92 : *
93 : * D: --RRRRRRSSSRRRRRRRR---
94 : * C: ------UUrrUUU---------
95 : *
96 : * CoW remapping must be done after the data block write completes,
97 : * because we don't want to destroy the old data fork map until we're sure
98 : * the new block has been written. Since the new mappings are kept in a
99 : * separate fork, we can simply iterate these mappings to find the ones
100 : * that cover the file blocks that we just CoW'd. For each extent, simply
101 : * unmap the corresponding range in the data fork, map the new range into
102 : * the data fork, and remove the extent from the CoW fork. Because of
103 : * the presence of the cowextsize hint, however, we must be careful
104 : * only to remap the blocks that we've actually written out -- we must
105 : * never remap delalloc reservations nor CoW staging blocks that have
106 : * yet to be written. This corresponds exactly to the real extents in
107 : * the CoW fork:
108 : *
109 : * D: --RRRRRRrrSRRRRRRRR---
110 : * C: ------UU--UUU---------
111 : *
112 : * Since the remapping operation can be applied to an arbitrary file
113 : * range, we record the need for the remap step as a flag in the ioend
114 : * instead of declaring a new IO type. This is required for direct io
115 : * because we only have ioend for the whole dio, and we have to be able to
116 : * remember the presence of unwritten blocks and CoW blocks with a single
117 : * ioend structure. Better yet, the more ground we can cover with one
118 : * ioend, the better.
119 : */
120 :
121 : /*
122 : * Given an AG extent, find the lowest-numbered run of shared blocks
123 : * within that range and return the range in fbno/flen. If
124 : * find_end_of_shared is true, return the longest contiguous extent of
125 : * shared blocks. If there are no shared extents, fbno and flen will
126 : * be set to NULLAGBLOCK and 0, respectively.
127 : */
128 : static int
129 247626143 : xfs_reflink_find_shared(
130 : struct xfs_perag *pag,
131 : struct xfs_trans *tp,
132 : xfs_agblock_t agbno,
133 : xfs_extlen_t aglen,
134 : xfs_agblock_t *fbno,
135 : xfs_extlen_t *flen,
136 : bool find_end_of_shared)
137 : {
138 247626143 : struct xfs_buf *agbp;
139 247626143 : struct xfs_btree_cur *cur;
140 247626143 : int error;
141 :
142 247626143 : error = xfs_alloc_read_agf(pag, tp, 0, &agbp);
143 247629459 : if (error)
144 : return error;
145 :
146 247629398 : cur = xfs_refcountbt_init_cursor(pag->pag_mount, tp, agbp, pag);
147 :
148 247629159 : error = xfs_refcount_find_shared(cur, agbno, aglen, fbno, flen,
149 : find_end_of_shared);
150 :
151 247628361 : xfs_btree_del_cursor(cur, error);
152 :
153 247629640 : xfs_trans_brelse(tp, agbp);
154 247629640 : return error;
155 : }
156 :
157 : /*
158 : * Trim the mapping to the next block where there's a change in the
159 : * shared/unshared status. More specifically, this means that we
160 : * find the lowest-numbered extent of shared blocks that coincides with
161 : * the given block mapping. If the shared extent overlaps the start of
162 : * the mapping, trim the mapping to the end of the shared extent. If
163 : * the shared region intersects the mapping, trim the mapping to the
164 : * start of the shared extent. If there are no shared regions that
165 : * overlap, just return the original extent.
166 : */
167 : int
168 11980034 : xfs_reflink_trim_around_shared(
169 : struct xfs_inode *ip,
170 : struct xfs_bmbt_irec *irec,
171 : bool *shared)
172 : {
173 11980034 : struct xfs_mount *mp = ip->i_mount;
174 11980034 : struct xfs_perag *pag;
175 11980034 : xfs_agblock_t agbno;
176 11980034 : xfs_extlen_t aglen;
177 11980034 : xfs_agblock_t fbno;
178 11980034 : xfs_extlen_t flen;
179 11980034 : int error = 0;
180 :
181 : /* Holes, unwritten, and delalloc extents cannot be shared */
182 11980034 : if (!xfs_is_cow_inode(ip) || !xfs_bmap_is_written_extent(irec)) {
183 3627504 : *shared = false;
184 3627504 : return 0;
185 : }
186 :
187 8352562 : trace_xfs_reflink_trim_around_shared(ip, irec);
188 :
189 8352566 : pag = xfs_perag_get(mp, XFS_FSB_TO_AGNO(mp, irec->br_startblock));
190 8352558 : agbno = XFS_FSB_TO_AGBNO(mp, irec->br_startblock);
191 8352560 : aglen = irec->br_blockcount;
192 :
193 8352560 : error = xfs_reflink_find_shared(pag, NULL, agbno, aglen, &fbno, &flen,
194 : true);
195 8352567 : xfs_perag_put(pag);
196 8352567 : if (error)
197 : return error;
198 :
199 8352466 : *shared = false;
200 8352466 : if (fbno == NULLAGBLOCK) {
201 : /* No shared blocks at all. */
202 : return 0;
203 : }
204 :
205 786565 : if (fbno == agbno) {
206 : /*
207 : * The start of this extent is shared. Truncate the
208 : * mapping at the end of the shared region so that a
209 : * subsequent iteration starts at the start of the
210 : * unshared region.
211 : */
212 773787 : irec->br_blockcount = flen;
213 773787 : *shared = true;
214 773787 : return 0;
215 : }
216 :
217 : /*
218 : * There's a shared extent midway through this extent.
219 : * Truncate the mapping at the start of the shared
220 : * extent so that a subsequent iteration starts at the
221 : * start of the shared region.
222 : */
223 12778 : irec->br_blockcount = fbno - agbno;
224 12778 : return 0;
225 : }
226 :
227 : int
228 7979341 : xfs_bmap_trim_cow(
229 : struct xfs_inode *ip,
230 : struct xfs_bmbt_irec *imap,
231 : bool *shared)
232 : {
233 : /* We can't update any real extents in always COW mode. */
234 7979341 : if (xfs_is_always_cow_inode(ip) &&
235 0 : !isnullstartblock(imap->br_startblock)) {
236 0 : *shared = true;
237 0 : return 0;
238 : }
239 :
240 : /* Trim the mapping to the nearest shared extent boundary. */
241 7979341 : return xfs_reflink_trim_around_shared(ip, imap, shared);
242 : }
243 :
244 : static int
245 1692682 : xfs_reflink_convert_cow_locked(
246 : struct xfs_inode *ip,
247 : xfs_fileoff_t offset_fsb,
248 : xfs_filblks_t count_fsb)
249 : {
250 1692682 : struct xfs_iext_cursor icur;
251 1692682 : struct xfs_bmbt_irec got;
252 1692682 : struct xfs_btree_cur *dummy_cur = NULL;
253 1692682 : int dummy_logflags;
254 1692682 : int error = 0;
255 :
256 1692682 : if (!xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &got))
257 : return 0;
258 :
259 3288102 : do {
260 3288102 : if (got.br_startoff >= offset_fsb + count_fsb)
261 : break;
262 1693741 : if (got.br_state == XFS_EXT_NORM)
263 9 : continue;
264 1693732 : if (WARN_ON_ONCE(isnullstartblock(got.br_startblock)))
265 : return -EIO;
266 :
267 1693732 : xfs_trim_extent(&got, offset_fsb, count_fsb);
268 1693734 : if (!got.br_blockcount)
269 0 : continue;
270 :
271 1693734 : got.br_state = XFS_EXT_NORM;
272 1693734 : error = xfs_bmap_add_extent_unwritten_real(NULL, ip,
273 : XFS_COW_FORK, &icur, &dummy_cur, &got,
274 : &dummy_logflags);
275 1693705 : if (error)
276 0 : return error;
277 1693714 : } while (xfs_iext_next_extent(ip->i_cowfp, &icur, &got));
278 :
279 : return error;
280 : }
281 :
282 : /* Convert all of the unwritten CoW extents in a file's range to real ones. */
283 : int
284 350155 : xfs_reflink_convert_cow(
285 : struct xfs_inode *ip,
286 : xfs_off_t offset,
287 : xfs_off_t count)
288 : {
289 350155 : struct xfs_mount *mp = ip->i_mount;
290 350155 : xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset);
291 350155 : xfs_fileoff_t end_fsb = XFS_B_TO_FSB(mp, offset + count);
292 350155 : xfs_filblks_t count_fsb = end_fsb - offset_fsb;
293 350155 : int error;
294 :
295 350155 : ASSERT(count != 0);
296 :
297 350155 : xfs_ilock(ip, XFS_ILOCK_EXCL);
298 350154 : error = xfs_reflink_convert_cow_locked(ip, offset_fsb, count_fsb);
299 350124 : xfs_iunlock(ip, XFS_ILOCK_EXCL);
300 350133 : return error;
301 : }
302 :
303 : /*
304 : * Find the extent that maps the given range in the COW fork. Even if the extent
305 : * is not shared we might have a preallocation for it in the COW fork. If so we
306 : * use it that rather than trigger a new allocation.
307 : */
308 : static int
309 3100717 : xfs_find_trim_cow_extent(
310 : struct xfs_inode *ip,
311 : struct xfs_bmbt_irec *imap,
312 : struct xfs_bmbt_irec *cmap,
313 : bool *shared,
314 : bool *found)
315 : {
316 3100717 : xfs_fileoff_t offset_fsb = imap->br_startoff;
317 3100717 : xfs_filblks_t count_fsb = imap->br_blockcount;
318 3100717 : struct xfs_iext_cursor icur;
319 :
320 3100717 : *found = false;
321 :
322 : /*
323 : * If we don't find an overlapping extent, trim the range we need to
324 : * allocate to fit the hole we found.
325 : */
326 3100717 : if (!xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, cmap))
327 194715 : cmap->br_startoff = offset_fsb + count_fsb;
328 3100717 : if (cmap->br_startoff > offset_fsb) {
329 1945958 : xfs_trim_extent(imap, imap->br_startoff,
330 : cmap->br_startoff - imap->br_startoff);
331 1945958 : return xfs_bmap_trim_cow(ip, imap, shared);
332 : }
333 :
334 1154759 : *shared = true;
335 1154759 : if (isnullstartblock(cmap->br_startblock)) {
336 920 : xfs_trim_extent(imap, cmap->br_startoff, cmap->br_blockcount);
337 920 : return 0;
338 : }
339 :
340 : /* real extent found - no need to allocate */
341 1153839 : xfs_trim_extent(cmap, offset_fsb, count_fsb);
342 1153839 : *found = true;
343 1153839 : return 0;
344 : }
345 :
346 : static int
347 1352049 : xfs_reflink_convert_unwritten(
348 : struct xfs_inode *ip,
349 : struct xfs_bmbt_irec *imap,
350 : struct xfs_bmbt_irec *cmap,
351 : bool convert_now)
352 : {
353 1352049 : xfs_fileoff_t offset_fsb = imap->br_startoff;
354 1352049 : xfs_filblks_t count_fsb = imap->br_blockcount;
355 1352049 : int error;
356 :
357 : /*
358 : * cmap might larger than imap due to cowextsize hint.
359 : */
360 1352049 : xfs_trim_extent(cmap, offset_fsb, count_fsb);
361 :
362 : /*
363 : * COW fork extents are supposed to remain unwritten until we're ready
364 : * to initiate a disk write. For direct I/O we are going to write the
365 : * data and need the conversion, but for buffered writes we're done.
366 : */
367 1352049 : if (!convert_now || cmap->br_state == XFS_EXT_NORM)
368 : return 0;
369 :
370 1342531 : trace_xfs_reflink_convert_cow(ip, cmap);
371 :
372 1342531 : error = xfs_reflink_convert_cow_locked(ip, offset_fsb, count_fsb);
373 1342531 : if (!error)
374 1342531 : cmap->br_state = XFS_EXT_NORM;
375 :
376 : return error;
377 : }
378 :
379 : static int
380 197798 : xfs_reflink_fill_cow_hole(
381 : struct xfs_inode *ip,
382 : struct xfs_bmbt_irec *imap,
383 : struct xfs_bmbt_irec *cmap,
384 : bool *shared,
385 : uint *lockmode,
386 : bool convert_now)
387 : {
388 197798 : struct xfs_mount *mp = ip->i_mount;
389 197798 : struct xfs_trans *tp;
390 197798 : xfs_filblks_t resaligned;
391 197798 : xfs_extlen_t resblks;
392 197798 : int nimaps;
393 197798 : int error;
394 197798 : bool found;
395 :
396 197798 : resaligned = xfs_aligned_fsb_count(imap->br_startoff,
397 : imap->br_blockcount, xfs_get_cowextsz_hint(ip));
398 197798 : resblks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
399 :
400 197798 : xfs_iunlock(ip, *lockmode);
401 197798 : *lockmode = 0;
402 :
403 197798 : error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write, resblks, 0,
404 : false, &tp);
405 197798 : if (error)
406 : return error;
407 :
408 197792 : *lockmode = XFS_ILOCK_EXCL;
409 :
410 197792 : error = xfs_find_trim_cow_extent(ip, imap, cmap, shared, &found);
411 197792 : if (error || !*shared)
412 0 : goto out_trans_cancel;
413 :
414 197792 : if (found) {
415 1 : xfs_trans_cancel(tp);
416 1 : goto convert;
417 : }
418 :
419 : /* Allocate the entire reservation as unwritten blocks. */
420 197791 : nimaps = 1;
421 197791 : error = xfs_bmapi_write(tp, ip, imap->br_startoff, imap->br_blockcount,
422 : XFS_BMAPI_COWFORK | XFS_BMAPI_PREALLOC, 0, cmap,
423 : &nimaps);
424 197791 : if (error)
425 13 : goto out_trans_cancel;
426 :
427 197778 : xfs_inode_set_cowblocks_tag(ip);
428 197778 : error = xfs_trans_commit(tp);
429 197778 : if (error)
430 : return error;
431 :
432 : /*
433 : * Allocation succeeded but the requested range was not even partially
434 : * satisfied? Bail out!
435 : */
436 197776 : if (nimaps == 0)
437 : return -ENOSPC;
438 :
439 197776 : convert:
440 197777 : return xfs_reflink_convert_unwritten(ip, imap, cmap, convert_now);
441 :
442 13 : out_trans_cancel:
443 13 : xfs_trans_cancel(tp);
444 13 : return error;
445 : }
446 :
447 : static int
448 434 : xfs_reflink_fill_delalloc(
449 : struct xfs_inode *ip,
450 : struct xfs_bmbt_irec *imap,
451 : struct xfs_bmbt_irec *cmap,
452 : bool *shared,
453 : uint *lockmode,
454 : bool convert_now)
455 : {
456 434 : struct xfs_mount *mp = ip->i_mount;
457 486 : struct xfs_trans *tp;
458 486 : int nimaps;
459 486 : int error;
460 486 : bool found;
461 :
462 486 : do {
463 486 : xfs_iunlock(ip, *lockmode);
464 486 : *lockmode = 0;
465 :
466 486 : error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write, 0, 0,
467 : false, &tp);
468 486 : if (error)
469 0 : return error;
470 :
471 486 : *lockmode = XFS_ILOCK_EXCL;
472 :
473 486 : error = xfs_find_trim_cow_extent(ip, imap, cmap, shared,
474 : &found);
475 486 : if (error || !*shared)
476 0 : goto out_trans_cancel;
477 :
478 486 : if (found) {
479 0 : xfs_trans_cancel(tp);
480 0 : break;
481 : }
482 :
483 486 : ASSERT(isnullstartblock(cmap->br_startblock) ||
484 : cmap->br_startblock == DELAYSTARTBLOCK);
485 :
486 : /*
487 : * Replace delalloc reservation with an unwritten extent.
488 : */
489 486 : nimaps = 1;
490 486 : error = xfs_bmapi_write(tp, ip, cmap->br_startoff,
491 : cmap->br_blockcount,
492 : XFS_BMAPI_COWFORK | XFS_BMAPI_PREALLOC, 0,
493 : cmap, &nimaps);
494 486 : if (error)
495 0 : goto out_trans_cancel;
496 :
497 486 : xfs_inode_set_cowblocks_tag(ip);
498 486 : error = xfs_trans_commit(tp);
499 486 : if (error)
500 0 : return error;
501 :
502 : /*
503 : * Allocation succeeded but the requested range was not even
504 : * partially satisfied? Bail out!
505 : */
506 486 : if (nimaps == 0)
507 : return -ENOSPC;
508 486 : } while (cmap->br_startoff + cmap->br_blockcount <= imap->br_startoff);
509 :
510 434 : return xfs_reflink_convert_unwritten(ip, imap, cmap, convert_now);
511 :
512 0 : out_trans_cancel:
513 0 : xfs_trans_cancel(tp);
514 0 : return error;
515 : }
516 :
517 : /* Allocate all CoW reservations covering a range of blocks in a file. */
518 : int
519 2902439 : xfs_reflink_allocate_cow(
520 : struct xfs_inode *ip,
521 : struct xfs_bmbt_irec *imap,
522 : struct xfs_bmbt_irec *cmap,
523 : bool *shared,
524 : uint *lockmode,
525 : bool convert_now)
526 : {
527 2902439 : int error;
528 2902439 : bool found;
529 :
530 2902439 : ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
531 2902439 : if (!ip->i_cowfp) {
532 0 : ASSERT(!xfs_is_reflink_inode(ip));
533 0 : xfs_ifork_init_cow(ip);
534 : }
535 :
536 2902439 : error = xfs_find_trim_cow_extent(ip, imap, cmap, shared, &found);
537 2902439 : if (error || !*shared)
538 1550369 : return error;
539 :
540 : /* CoW fork has a real extent */
541 1352070 : if (found)
542 1153838 : return xfs_reflink_convert_unwritten(ip, imap, cmap,
543 : convert_now);
544 :
545 : /*
546 : * CoW fork does not have an extent and data extent is shared.
547 : * Allocate a real extent in the CoW fork.
548 : */
549 198232 : if (cmap->br_startoff > imap->br_startoff)
550 197798 : return xfs_reflink_fill_cow_hole(ip, imap, cmap, shared,
551 : lockmode, convert_now);
552 :
553 : /*
554 : * CoW fork has a delalloc reservation. Replace it with a real extent.
555 : * There may or may not be a data fork mapping.
556 : */
557 434 : if (isnullstartblock(cmap->br_startblock) ||
558 : cmap->br_startblock == DELAYSTARTBLOCK)
559 434 : return xfs_reflink_fill_delalloc(ip, imap, cmap, shared,
560 : lockmode, convert_now);
561 :
562 : /* Shouldn't get here. */
563 0 : ASSERT(0);
564 0 : return -EFSCORRUPTED;
565 : }
566 :
567 : /*
568 : * Cancel CoW reservations for some block range of an inode.
569 : *
570 : * If cancel_real is true this function cancels all COW fork extents for the
571 : * inode; if cancel_real is false, real extents are not cleared.
572 : *
573 : * Caller must have already joined the inode to the current transaction. The
574 : * inode will be joined to the transaction returned to the caller.
575 : */
576 : int
577 10000297 : xfs_reflink_cancel_cow_blocks(
578 : struct xfs_inode *ip,
579 : struct xfs_trans **tpp,
580 : xfs_fileoff_t offset_fsb,
581 : xfs_fileoff_t end_fsb,
582 : bool cancel_real)
583 : {
584 10000297 : struct xfs_ifork *ifp = xfs_ifork_ptr(ip, XFS_COW_FORK);
585 10000297 : struct xfs_bmbt_irec got, del;
586 10000297 : struct xfs_iext_cursor icur;
587 10000297 : int error = 0;
588 :
589 20000594 : if (!xfs_inode_has_cow_data(ip))
590 : return 0;
591 310129 : if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &icur, &got))
592 : return 0;
593 :
594 : /* Walk backwards until we're out of the I/O range... */
595 490517 : while (got.br_startoff + got.br_blockcount > offset_fsb) {
596 233785 : del = got;
597 233785 : xfs_trim_extent(&del, offset_fsb, end_fsb - offset_fsb);
598 :
599 : /* Extent delete may have bumped ext forward */
600 233784 : if (!del.br_blockcount) {
601 2 : xfs_iext_prev(ifp, &icur);
602 2 : goto next_extent;
603 : }
604 :
605 233782 : trace_xfs_reflink_cancel_cow(ip, &del);
606 :
607 233782 : if (isnullstartblock(del.br_startblock)) {
608 18151 : error = xfs_bmap_del_extent_delay(ip, XFS_COW_FORK,
609 : &icur, &got, &del);
610 18151 : if (error)
611 : break;
612 215631 : } else if (del.br_state == XFS_EXT_UNWRITTEN || cancel_real) {
613 215631 : ASSERT((*tpp)->t_highest_agno == NULLAGNUMBER);
614 :
615 : /* Free the CoW orphan record. */
616 215631 : xfs_refcount_free_cow_extent(*tpp, del.br_startblock,
617 215631 : del.br_blockcount);
618 :
619 215632 : error = xfs_free_extent_later(*tpp, del.br_startblock,
620 : del.br_blockcount, NULL,
621 : XFS_AG_RESV_NONE);
622 215632 : if (error)
623 : break;
624 :
625 : /* Roll the transaction */
626 215632 : error = xfs_defer_finish(tpp);
627 215632 : if (error)
628 : break;
629 :
630 : /* Remove the mapping from the CoW fork. */
631 215608 : xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
632 :
633 : /* Remove the quota reservation */
634 215608 : error = xfs_quota_unreserve_blkres(ip,
635 215608 : del.br_blockcount);
636 215608 : if (error)
637 : break;
638 : } else {
639 : /* Didn't do anything, push cursor back. */
640 0 : xfs_iext_prev(ifp, &icur);
641 : }
642 233761 : next_extent:
643 233761 : if (!xfs_iext_get_extent(ifp, &icur, &got))
644 : break;
645 : }
646 :
647 : /* clear tag if cow fork is emptied */
648 310129 : if (!ifp->if_bytes)
649 53361 : xfs_inode_clear_cowblocks_tag(ip);
650 : return error;
651 : }
652 :
653 : /*
654 : * Cancel CoW reservations for some byte range of an inode.
655 : *
656 : * If cancel_real is true this function cancels all COW fork extents for the
657 : * inode; if cancel_real is false, real extents are not cleared.
658 : */
659 : int
660 86336 : xfs_reflink_cancel_cow_range(
661 : struct xfs_inode *ip,
662 : xfs_off_t offset,
663 : xfs_off_t count,
664 : bool cancel_real)
665 : {
666 86336 : struct xfs_trans *tp;
667 86336 : xfs_fileoff_t offset_fsb;
668 86336 : xfs_fileoff_t end_fsb;
669 86336 : int error;
670 :
671 86336 : trace_xfs_reflink_cancel_cow_range(ip, offset, count);
672 86336 : ASSERT(ip->i_cowfp);
673 :
674 86336 : offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
675 86336 : if (count == NULLFILEOFF)
676 : end_fsb = NULLFILEOFF;
677 : else
678 167 : end_fsb = XFS_B_TO_FSB(ip->i_mount, offset + count);
679 :
680 : /* Start a rolling transaction to remove the mappings */
681 86336 : error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_write,
682 : 0, 0, 0, &tp);
683 86336 : if (error)
684 1 : goto out;
685 :
686 86335 : xfs_ilock(ip, XFS_ILOCK_EXCL);
687 86335 : xfs_trans_ijoin(tp, ip, 0);
688 :
689 : /* Scrape out the old CoW reservations */
690 86335 : error = xfs_reflink_cancel_cow_blocks(ip, &tp, offset_fsb, end_fsb,
691 : cancel_real);
692 86335 : if (error)
693 24 : goto out_cancel;
694 :
695 86311 : error = xfs_trans_commit(tp);
696 :
697 86311 : xfs_iunlock(ip, XFS_ILOCK_EXCL);
698 86311 : return error;
699 :
700 : out_cancel:
701 24 : xfs_trans_cancel(tp);
702 24 : xfs_iunlock(ip, XFS_ILOCK_EXCL);
703 25 : out:
704 25 : trace_xfs_reflink_cancel_cow_range_error(ip, error, _RET_IP_);
705 25 : return error;
706 : }
707 :
708 : /*
709 : * Remap part of the CoW fork into the data fork.
710 : *
711 : * We aim to remap the range starting at @offset_fsb and ending at @end_fsb
712 : * into the data fork; this function will remap what it can (at the end of the
713 : * range) and update @end_fsb appropriately. Each remap gets its own
714 : * transaction because we can end up merging and splitting bmbt blocks for
715 : * every remap operation and we'd like to keep the block reservation
716 : * requirements as low as possible.
717 : */
718 : STATIC int
719 1865522 : xfs_reflink_end_cow_extent(
720 : struct xfs_inode *ip,
721 : xfs_fileoff_t *offset_fsb,
722 : xfs_fileoff_t end_fsb)
723 : {
724 1865522 : struct xfs_iext_cursor icur;
725 1865522 : struct xfs_bmbt_irec got, del, data;
726 1865522 : struct xfs_mount *mp = ip->i_mount;
727 1865522 : struct xfs_trans *tp;
728 1865522 : struct xfs_ifork *ifp = xfs_ifork_ptr(ip, XFS_COW_FORK);
729 1865522 : unsigned int resblks;
730 1865522 : int nmaps;
731 1865522 : int error;
732 :
733 : /* No COW extents? That's easy! */
734 1865522 : if (ifp->if_bytes == 0) {
735 210 : *offset_fsb = end_fsb;
736 210 : return 0;
737 : }
738 :
739 1865312 : resblks = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
740 1865312 : error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0,
741 : XFS_TRANS_RESERVE, &tp);
742 1865312 : if (error)
743 : return error;
744 :
745 : /*
746 : * Lock the inode. We have to ijoin without automatic unlock because
747 : * the lead transaction is the refcountbt record deletion; the data
748 : * fork update follows as a deferred log item.
749 : */
750 1865312 : xfs_ilock(ip, XFS_ILOCK_EXCL);
751 1865312 : xfs_trans_ijoin(tp, ip, 0);
752 :
753 1865312 : error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
754 : XFS_IEXT_REFLINK_END_COW_CNT);
755 1865312 : if (error == -EFBIG)
756 4 : error = xfs_iext_count_upgrade(tp, ip,
757 : XFS_IEXT_REFLINK_END_COW_CNT);
758 1865312 : if (error)
759 4 : goto out_cancel;
760 :
761 : /*
762 : * In case of racing, overlapping AIO writes no COW extents might be
763 : * left by the time I/O completes for the loser of the race. In that
764 : * case we are done.
765 : */
766 1865308 : if (!xfs_iext_lookup_extent(ip, ifp, *offset_fsb, &icur, &got) ||
767 1864845 : got.br_startoff >= end_fsb) {
768 20681 : *offset_fsb = end_fsb;
769 20681 : goto out_cancel;
770 : }
771 :
772 : /*
773 : * Only remap real extents that contain data. With AIO, speculative
774 : * preallocations can leak into the range we are called upon, and we
775 : * need to skip them. Preserve @got for the eventual CoW fork
776 : * deletion; from now on @del represents the mapping that we're
777 : * actually remapping.
778 : */
779 1846466 : while (!xfs_bmap_is_written_extent(&got)) {
780 2061 : if (!xfs_iext_next_extent(ifp, &icur, &got) ||
781 2058 : got.br_startoff >= end_fsb) {
782 222 : *offset_fsb = end_fsb;
783 222 : goto out_cancel;
784 : }
785 : }
786 1844405 : del = got;
787 :
788 : /* Grab the corresponding mapping in the data fork. */
789 1844405 : nmaps = 1;
790 1844405 : error = xfs_bmapi_read(ip, del.br_startoff, del.br_blockcount, &data,
791 : &nmaps, 0);
792 1844405 : if (error)
793 29 : goto out_cancel;
794 :
795 : /* We can only remap the smaller of the two extent sizes. */
796 1844376 : data.br_blockcount = min(data.br_blockcount, del.br_blockcount);
797 1844376 : del.br_blockcount = data.br_blockcount;
798 :
799 1844376 : trace_xfs_reflink_cow_remap_from(ip, &del);
800 1844376 : trace_xfs_reflink_cow_remap_to(ip, &data);
801 :
802 3601821 : if (xfs_bmap_is_real_extent(&data)) {
803 : /*
804 : * If the extent we're remapping is backed by storage (written
805 : * or not), unmap the extent and drop its refcount.
806 : */
807 1757445 : xfs_bmap_unmap_extent(tp, ip, &data);
808 1757445 : xfs_refcount_decrease_extent(tp, &data);
809 1757445 : xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT,
810 1757445 : -data.br_blockcount);
811 86931 : } else if (data.br_startblock == DELAYSTARTBLOCK) {
812 19878 : int done;
813 :
814 : /*
815 : * If the extent we're remapping is a delalloc reservation,
816 : * we can use the regular bunmapi function to release the
817 : * incore state. Dropping the delalloc reservation takes care
818 : * of the quota reservation for us.
819 : */
820 19878 : error = xfs_bunmapi(NULL, ip, data.br_startoff,
821 : data.br_blockcount, 0, 1, &done);
822 19878 : if (error)
823 0 : goto out_cancel;
824 19878 : ASSERT(done);
825 : }
826 :
827 : /* Free the CoW orphan record. */
828 1844376 : xfs_refcount_free_cow_extent(tp, del.br_startblock, del.br_blockcount);
829 :
830 : /* Map the new blocks into the data fork. */
831 1844376 : xfs_bmap_map_extent(tp, ip, &del);
832 :
833 : /* Charge this new data fork mapping to the on-disk quota. */
834 1844376 : xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_DELBCOUNT,
835 1844376 : (long)del.br_blockcount);
836 :
837 : /* Remove the mapping from the CoW fork. */
838 1844376 : xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
839 :
840 1844376 : error = xfs_trans_commit(tp);
841 1844376 : xfs_iunlock(ip, XFS_ILOCK_EXCL);
842 1844376 : if (error)
843 : return error;
844 :
845 : /* Update the caller about how much progress we made. */
846 1844372 : *offset_fsb = del.br_startoff + del.br_blockcount;
847 1844372 : return 0;
848 :
849 20936 : out_cancel:
850 20936 : xfs_trans_cancel(tp);
851 20936 : xfs_iunlock(ip, XFS_ILOCK_EXCL);
852 20936 : return error;
853 : }
854 :
855 : /*
856 : * Remap parts of a file's data fork after a successful CoW.
857 : */
858 : int
859 1453629 : xfs_reflink_end_cow(
860 : struct xfs_inode *ip,
861 : xfs_off_t offset,
862 : xfs_off_t count)
863 : {
864 1453629 : xfs_fileoff_t offset_fsb;
865 1453629 : xfs_fileoff_t end_fsb;
866 1453629 : int error = 0;
867 :
868 1453629 : trace_xfs_reflink_end_cow(ip, offset, count);
869 :
870 1453629 : offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
871 1453629 : end_fsb = XFS_B_TO_FSB(ip->i_mount, offset + count);
872 :
873 : /*
874 : * Walk forwards until we've remapped the I/O range. The loop function
875 : * repeatedly cycles the ILOCK to allocate one transaction per remapped
876 : * extent.
877 : *
878 : * If we're being called by writeback then the pages will still
879 : * have PageWriteback set, which prevents races with reflink remapping
880 : * and truncate. Reflink remapping prevents races with writeback by
881 : * taking the iolock and mmaplock before flushing the pages and
882 : * remapping, which means there won't be any further writeback or page
883 : * cache dirtying until the reflink completes.
884 : *
885 : * We should never have two threads issuing writeback for the same file
886 : * region. There are also have post-eof checks in the writeback
887 : * preparation code so that we don't bother writing out pages that are
888 : * about to be truncated.
889 : *
890 : * If we're being called as part of directio write completion, the dio
891 : * count is still elevated, which reflink and truncate will wait for.
892 : * Reflink remapping takes the iolock and mmaplock and waits for
893 : * pending dio to finish, which should prevent any directio until the
894 : * remap completes. Multiple concurrent directio writes to the same
895 : * region are handled by end_cow processing only occurring for the
896 : * threads which succeed; the outcome of multiple overlapping direct
897 : * writes is not well defined anyway.
898 : *
899 : * It's possible that a buffered write and a direct write could collide
900 : * here (the buffered write stumbles in after the dio flushes and
901 : * invalidates the page cache and immediately queues writeback), but we
902 : * have never supported this 100%. If either disk write succeeds the
903 : * blocks will be remapped.
904 : */
905 3319151 : while (end_fsb > offset_fsb && !error)
906 1865522 : error = xfs_reflink_end_cow_extent(ip, &offset_fsb, end_fsb);
907 :
908 1453629 : if (error)
909 37 : trace_xfs_reflink_end_cow_error(ip, error, _RET_IP_);
910 1453629 : return error;
911 : }
912 :
913 : /*
914 : * Free all CoW staging blocks that are still referenced by the ondisk refcount
915 : * metadata. The ondisk metadata does not track which inode created the
916 : * staging extent, so callers must ensure that there are no cached inodes with
917 : * live CoW staging extents.
918 : */
919 : int
920 10292 : xfs_reflink_recover_cow(
921 : struct xfs_mount *mp)
922 : {
923 10292 : struct xfs_perag *pag;
924 10292 : xfs_agnumber_t agno;
925 10292 : int error = 0;
926 :
927 10292 : if (!xfs_has_reflink(mp))
928 : return 0;
929 :
930 51410 : for_each_perag(mp, agno, pag) {
931 41126 : error = xfs_refcount_recover_cow_leftovers(mp, pag);
932 41126 : if (error) {
933 8 : xfs_perag_rele(pag);
934 8 : break;
935 : }
936 : }
937 :
938 : return error;
939 : }
940 :
941 : /*
942 : * Reflinking (Block) Ranges of Two Files Together
943 : *
944 : * First, ensure that the reflink flag is set on both inodes. The flag is an
945 : * optimization to avoid unnecessary refcount btree lookups in the write path.
946 : *
947 : * Now we can iteratively remap the range of extents (and holes) in src to the
948 : * corresponding ranges in dest. Let drange and srange denote the ranges of
949 : * logical blocks in dest and src touched by the reflink operation.
950 : *
951 : * While the length of drange is greater than zero,
952 : * - Read src's bmbt at the start of srange ("imap")
953 : * - If imap doesn't exist, make imap appear to start at the end of srange
954 : * with zero length.
955 : * - If imap starts before srange, advance imap to start at srange.
956 : * - If imap goes beyond srange, truncate imap to end at the end of srange.
957 : * - Punch (imap start - srange start + imap len) blocks from dest at
958 : * offset (drange start).
959 : * - If imap points to a real range of pblks,
960 : * > Increase the refcount of the imap's pblks
961 : * > Map imap's pblks into dest at the offset
962 : * (drange start + imap start - srange start)
963 : * - Advance drange and srange by (imap start - srange start + imap len)
964 : *
965 : * Finally, if the reflink made dest longer, update both the in-core and
966 : * on-disk file sizes.
967 : *
968 : * ASCII Art Demonstration:
969 : *
970 : * Let's say we want to reflink this source file:
971 : *
972 : * ----SSSSSSS-SSSSS----SSSSSS (src file)
973 : * <-------------------->
974 : *
975 : * into this destination file:
976 : *
977 : * --DDDDDDDDDDDDDDDDDDD--DDD (dest file)
978 : * <-------------------->
979 : * '-' means a hole, and 'S' and 'D' are written blocks in the src and dest.
980 : * Observe that the range has different logical offsets in either file.
981 : *
982 : * Consider that the first extent in the source file doesn't line up with our
983 : * reflink range. Unmapping and remapping are separate operations, so we can
984 : * unmap more blocks from the destination file than we remap.
985 : *
986 : * ----SSSSSSS-SSSSS----SSSSSS
987 : * <------->
988 : * --DDDDD---------DDDDD--DDD
989 : * <------->
990 : *
991 : * Now remap the source extent into the destination file:
992 : *
993 : * ----SSSSSSS-SSSSS----SSSSSS
994 : * <------->
995 : * --DDDDD--SSSSSSSDDDDD--DDD
996 : * <------->
997 : *
998 : * Do likewise with the second hole and extent in our range. Holes in the
999 : * unmap range don't affect our operation.
1000 : *
1001 : * ----SSSSSSS-SSSSS----SSSSSS
1002 : * <---->
1003 : * --DDDDD--SSSSSSS-SSSSS-DDD
1004 : * <---->
1005 : *
1006 : * Finally, unmap and remap part of the third extent. This will increase the
1007 : * size of the destination file.
1008 : *
1009 : * ----SSSSSSS-SSSSS----SSSSSS
1010 : * <----->
1011 : * --DDDDD--SSSSSSS-SSSSS----SSS
1012 : * <----->
1013 : *
1014 : * Once we update the destination file's i_size, we're done.
1015 : */
1016 :
1017 : /*
1018 : * Ensure the reflink bit is set in both inodes.
1019 : */
1020 : STATIC int
1021 79906286 : xfs_reflink_set_inode_flag(
1022 : struct xfs_inode *src,
1023 : struct xfs_inode *dest)
1024 : {
1025 79906286 : struct xfs_mount *mp = src->i_mount;
1026 79906286 : int error;
1027 79906286 : struct xfs_trans *tp;
1028 :
1029 79906286 : if (xfs_is_reflink_inode(src) && xfs_is_reflink_inode(dest))
1030 : return 0;
1031 :
1032 1995955 : error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
1033 1996918 : if (error)
1034 0 : goto out_error;
1035 :
1036 : /* Lock both files against IO */
1037 1996918 : if (src->i_ino == dest->i_ino)
1038 67529 : xfs_ilock(src, XFS_ILOCK_EXCL);
1039 : else
1040 1929389 : xfs_lock_two_inodes(src, XFS_ILOCK_EXCL, dest, XFS_ILOCK_EXCL);
1041 :
1042 1996929 : if (!xfs_is_reflink_inode(src)) {
1043 237310 : trace_xfs_reflink_set_inode_flag(src);
1044 237310 : xfs_trans_ijoin(tp, src, XFS_ILOCK_EXCL);
1045 237310 : src->i_diflags2 |= XFS_DIFLAG2_REFLINK;
1046 237310 : xfs_trans_log_inode(tp, src, XFS_ILOG_CORE);
1047 237310 : xfs_ifork_init_cow(src);
1048 : } else
1049 1759619 : xfs_iunlock(src, XFS_ILOCK_EXCL);
1050 :
1051 1996929 : if (src->i_ino == dest->i_ino)
1052 67529 : goto commit_flags;
1053 :
1054 1929400 : if (!xfs_is_reflink_inode(dest)) {
1055 1800463 : trace_xfs_reflink_set_inode_flag(dest);
1056 1800463 : xfs_trans_ijoin(tp, dest, XFS_ILOCK_EXCL);
1057 1800462 : dest->i_diflags2 |= XFS_DIFLAG2_REFLINK;
1058 1800462 : xfs_trans_log_inode(tp, dest, XFS_ILOG_CORE);
1059 1800463 : xfs_ifork_init_cow(dest);
1060 : } else
1061 128937 : xfs_iunlock(dest, XFS_ILOCK_EXCL);
1062 :
1063 1996929 : commit_flags:
1064 1996929 : error = xfs_trans_commit(tp);
1065 1996925 : if (error)
1066 1 : goto out_error;
1067 : return error;
1068 :
1069 1 : out_error:
1070 1 : trace_xfs_reflink_set_inode_flag_error(dest, error, _RET_IP_);
1071 1 : return error;
1072 : }
1073 :
1074 : /*
1075 : * Update destination inode size & cowextsize hint, if necessary.
1076 : */
1077 : int
1078 79315327 : xfs_reflink_update_dest(
1079 : struct xfs_inode *dest,
1080 : xfs_off_t newlen,
1081 : xfs_extlen_t cowextsize,
1082 : unsigned int remap_flags)
1083 : {
1084 79315327 : struct xfs_mount *mp = dest->i_mount;
1085 79315327 : struct xfs_trans *tp;
1086 79315327 : int error;
1087 :
1088 79315327 : if (newlen <= i_size_read(VFS_I(dest)) && cowextsize == 0)
1089 : return 0;
1090 :
1091 1366277 : error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
1092 1367335 : if (error)
1093 0 : goto out_error;
1094 :
1095 1367335 : xfs_ilock(dest, XFS_ILOCK_EXCL);
1096 1367334 : xfs_trans_ijoin(tp, dest, XFS_ILOCK_EXCL);
1097 :
1098 1367335 : if (newlen > i_size_read(VFS_I(dest))) {
1099 1367328 : trace_xfs_reflink_update_inode_size(dest, newlen);
1100 1367314 : i_size_write(VFS_I(dest), newlen);
1101 1367314 : dest->i_disk_size = newlen;
1102 : }
1103 :
1104 1367321 : if (cowextsize) {
1105 6 : dest->i_cowextsize = cowextsize;
1106 6 : dest->i_diflags2 |= XFS_DIFLAG2_COWEXTSIZE;
1107 : }
1108 :
1109 1367321 : xfs_trans_log_inode(tp, dest, XFS_ILOG_CORE);
1110 :
1111 1367334 : error = xfs_trans_commit(tp);
1112 1367335 : if (error)
1113 0 : goto out_error;
1114 : return error;
1115 :
1116 0 : out_error:
1117 0 : trace_xfs_reflink_update_inode_size_error(dest, error, _RET_IP_);
1118 0 : return error;
1119 : }
1120 :
1121 : /*
1122 : * Do we have enough reserve in this AG to handle a reflink? The refcount
1123 : * btree already reserved all the space it needs, but the rmap btree can grow
1124 : * infinitely, so we won't allow more reflinks when the AG is down to the
1125 : * btree reserves.
1126 : */
1127 : static int
1128 48152505 : xfs_reflink_ag_has_free_space(
1129 : struct xfs_mount *mp,
1130 : xfs_agnumber_t agno)
1131 : {
1132 48152505 : struct xfs_perag *pag;
1133 48152505 : int error = 0;
1134 :
1135 48152505 : if (!xfs_has_rmapbt(mp))
1136 : return 0;
1137 :
1138 48152505 : pag = xfs_perag_get(mp, agno);
1139 96305002 : if (xfs_ag_resv_critical(pag, XFS_AG_RESV_RMAPBT) ||
1140 48152499 : xfs_ag_resv_critical(pag, XFS_AG_RESV_METADATA))
1141 : error = -ENOSPC;
1142 48152504 : xfs_perag_put(pag);
1143 48152504 : return error;
1144 : }
1145 :
1146 : /*
1147 : * Remap the given extent into the file. The dmap blockcount will be set to
1148 : * the number of blocks that were actually remapped.
1149 : */
1150 : STATIC int
1151 137376877 : xfs_reflink_remap_extent(
1152 : struct xfs_inode *ip,
1153 : struct xfs_bmbt_irec *dmap,
1154 : xfs_off_t new_isize)
1155 : {
1156 137376877 : struct xfs_bmbt_irec smap;
1157 137376877 : struct xfs_mount *mp = ip->i_mount;
1158 137376877 : struct xfs_trans *tp;
1159 137376877 : xfs_off_t newlen;
1160 137376877 : int64_t qdelta = 0;
1161 137376877 : unsigned int resblks;
1162 137376877 : bool quota_reserved = true;
1163 137376877 : bool smap_real;
1164 137376877 : bool dmap_written = xfs_bmap_is_written_extent(dmap);
1165 137376877 : int iext_delta = 0;
1166 137376877 : int nimaps;
1167 137376877 : int error;
1168 :
1169 : /*
1170 : * Start a rolling transaction to switch the mappings.
1171 : *
1172 : * Adding a written extent to the extent map can cause a bmbt split,
1173 : * and removing a mapped extent from the extent can cause a bmbt split.
1174 : * The two operations cannot both cause a split since they operate on
1175 : * the same index in the bmap btree, so we only need a reservation for
1176 : * one bmbt split if either thing is happening. However, we haven't
1177 : * locked the inode yet, so we reserve assuming this is the case.
1178 : *
1179 : * The first allocation call tries to reserve enough space to handle
1180 : * mapping dmap into a sparse part of the file plus the bmbt split. We
1181 : * haven't locked the inode or read the existing mapping yet, so we do
1182 : * not know for sure that we need the space. This should succeed most
1183 : * of the time.
1184 : *
1185 : * If the first attempt fails, try again but reserving only enough
1186 : * space to handle a bmbt split. This is the hard minimum requirement,
1187 : * and we revisit quota reservations later when we know more about what
1188 : * we're remapping.
1189 : */
1190 137376877 : resblks = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
1191 137376877 : error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write,
1192 137376877 : resblks + dmap->br_blockcount, 0, false, &tp);
1193 137377893 : if (error == -EDQUOT || error == -ENOSPC) {
1194 2257699 : quota_reserved = false;
1195 2257699 : error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write,
1196 : resblks, 0, false, &tp);
1197 : }
1198 137377585 : if (error)
1199 589273 : goto out;
1200 :
1201 : /*
1202 : * Read what's currently mapped in the destination file into smap.
1203 : * If smap isn't a hole, we will have to remove it before we can add
1204 : * dmap to the destination file.
1205 : */
1206 136788312 : nimaps = 1;
1207 136788312 : error = xfs_bmapi_read(ip, dmap->br_startoff, dmap->br_blockcount,
1208 : &smap, &nimaps, 0);
1209 136786794 : if (error)
1210 12 : goto out_cancel;
1211 136786782 : ASSERT(nimaps == 1 && smap.br_startoff == dmap->br_startoff);
1212 136786782 : smap_real = xfs_bmap_is_real_extent(&smap);
1213 :
1214 : /*
1215 : * We can only remap as many blocks as the smaller of the two extent
1216 : * maps, because we can only remap one extent at a time.
1217 : */
1218 136786782 : dmap->br_blockcount = min(dmap->br_blockcount, smap.br_blockcount);
1219 136786782 : ASSERT(dmap->br_blockcount == smap.br_blockcount);
1220 :
1221 136786782 : trace_xfs_reflink_remap_extent_dest(ip, &smap);
1222 :
1223 : /*
1224 : * Two extents mapped to the same physical block must not have
1225 : * different states; that's filesystem corruption. Move on to the next
1226 : * extent if they're both holes or both the same physical extent.
1227 : */
1228 136787816 : if (dmap->br_startblock == smap.br_startblock) {
1229 84644987 : if (dmap->br_state != smap.br_state)
1230 0 : error = -EFSCORRUPTED;
1231 84644987 : goto out_cancel;
1232 : }
1233 :
1234 : /* If both extents are unwritten, leave them alone. */
1235 52142829 : if (dmap->br_state == XFS_EXT_UNWRITTEN &&
1236 1897510 : smap.br_state == XFS_EXT_UNWRITTEN)
1237 76694 : goto out_cancel;
1238 :
1239 : /* No reflinking if the AG of the dest mapping is low on space. */
1240 52066135 : if (dmap_written) {
1241 96305010 : error = xfs_reflink_ag_has_free_space(mp,
1242 48152505 : XFS_FSB_TO_AGNO(mp, dmap->br_startblock));
1243 48152504 : if (error)
1244 6 : goto out_cancel;
1245 : }
1246 :
1247 : /*
1248 : * Increase quota reservation if we think the quota block counter for
1249 : * this file could increase.
1250 : *
1251 : * If we are mapping a written extent into the file, we need to have
1252 : * enough quota block count reservation to handle the blocks in that
1253 : * extent. We log only the delta to the quota block counts, so if the
1254 : * extent we're unmapping also has blocks allocated to it, we don't
1255 : * need a quota reservation for the extent itself.
1256 : *
1257 : * Note that if we're replacing a delalloc reservation with a written
1258 : * extent, we have to take the full quota reservation because removing
1259 : * the delalloc reservation gives the block count back to the quota
1260 : * count. This is suboptimal, but the VFS flushed the dest range
1261 : * before we started. That should have removed all the delalloc
1262 : * reservations, but we code defensively.
1263 : *
1264 : * xfs_trans_alloc_inode above already tried to grab an even larger
1265 : * quota reservation, and kicked off a blockgc scan if it couldn't.
1266 : * If we can't get a potentially smaller quota reservation now, we're
1267 : * done.
1268 : */
1269 52066128 : if (!quota_reserved && !smap_real && dmap_written) {
1270 16628 : error = xfs_trans_reserve_quota_nblks(tp, ip,
1271 16628 : dmap->br_blockcount, 0, false);
1272 16628 : if (error)
1273 0 : goto out_cancel;
1274 : }
1275 :
1276 52066128 : if (smap_real)
1277 2454314 : ++iext_delta;
1278 :
1279 52066128 : if (dmap_written)
1280 48152498 : ++iext_delta;
1281 :
1282 52066128 : error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK, iext_delta);
1283 52066128 : if (error == -EFBIG)
1284 6 : error = xfs_iext_count_upgrade(tp, ip, iext_delta);
1285 52066128 : if (error)
1286 6 : goto out_cancel;
1287 :
1288 52066122 : if (smap_real) {
1289 : /*
1290 : * If the extent we're unmapping is backed by storage (written
1291 : * or not), unmap the extent and drop its refcount.
1292 : */
1293 2454308 : xfs_bmap_unmap_extent(tp, ip, &smap);
1294 2454310 : xfs_refcount_decrease_extent(tp, &smap);
1295 2454311 : qdelta -= smap.br_blockcount;
1296 49611814 : } else if (smap.br_startblock == DELAYSTARTBLOCK) {
1297 139 : int done;
1298 :
1299 : /*
1300 : * If the extent we're unmapping is a delalloc reservation,
1301 : * we can use the regular bunmapi function to release the
1302 : * incore state. Dropping the delalloc reservation takes care
1303 : * of the quota reservation for us.
1304 : */
1305 139 : error = xfs_bunmapi(NULL, ip, smap.br_startoff,
1306 : smap.br_blockcount, 0, 1, &done);
1307 139 : if (error)
1308 0 : goto out_cancel;
1309 139 : ASSERT(done);
1310 : }
1311 :
1312 : /*
1313 : * If the extent we're sharing is backed by written storage, increase
1314 : * its refcount and map it into the file.
1315 : */
1316 52066125 : if (dmap_written) {
1317 48152493 : xfs_refcount_increase_extent(tp, dmap);
1318 48152493 : xfs_bmap_map_extent(tp, ip, dmap);
1319 48152492 : qdelta += dmap->br_blockcount;
1320 : }
1321 :
1322 52066124 : xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT, qdelta);
1323 :
1324 : /* Update dest isize if needed. */
1325 52066120 : newlen = XFS_FSB_TO_B(mp, dmap->br_startoff + dmap->br_blockcount);
1326 52066120 : newlen = min_t(xfs_off_t, newlen, new_isize);
1327 52066120 : if (newlen > i_size_read(VFS_I(ip))) {
1328 47465660 : trace_xfs_reflink_update_inode_size(ip, newlen);
1329 47465660 : i_size_write(VFS_I(ip), newlen);
1330 47465660 : ip->i_disk_size = newlen;
1331 47465660 : xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
1332 : }
1333 :
1334 : /* Commit everything and unlock. */
1335 52066120 : error = xfs_trans_commit(tp);
1336 52066124 : goto out_unlock;
1337 :
1338 84721705 : out_cancel:
1339 84721705 : xfs_trans_cancel(tp);
1340 136787220 : out_unlock:
1341 136787220 : xfs_iunlock(ip, XFS_ILOCK_EXCL);
1342 137376612 : out:
1343 137376612 : if (error)
1344 589988 : trace_xfs_reflink_remap_extent_error(ip, error, _RET_IP_);
1345 137376622 : return error;
1346 : }
1347 :
1348 : /* Remap a range of one file to the other. */
1349 : int
1350 79904425 : xfs_reflink_remap_blocks(
1351 : struct xfs_inode *src,
1352 : loff_t pos_in,
1353 : struct xfs_inode *dest,
1354 : loff_t pos_out,
1355 : loff_t remap_len,
1356 : loff_t *remapped)
1357 : {
1358 79904425 : struct xfs_bmbt_irec imap;
1359 79904425 : struct xfs_mount *mp = src->i_mount;
1360 79904425 : xfs_fileoff_t srcoff = XFS_B_TO_FSBT(mp, pos_in);
1361 79904425 : xfs_fileoff_t destoff = XFS_B_TO_FSBT(mp, pos_out);
1362 79904425 : xfs_filblks_t len;
1363 79904425 : xfs_filblks_t remapped_len = 0;
1364 79904425 : xfs_off_t new_isize = pos_out + remap_len;
1365 79904425 : int nimaps;
1366 79904425 : int error = 0;
1367 :
1368 79904425 : len = min_t(xfs_filblks_t, XFS_B_TO_FSB(mp, remap_len),
1369 : XFS_MAX_FILEOFF);
1370 :
1371 79904425 : trace_xfs_reflink_remap_blocks(src, srcoff, len, dest, destoff);
1372 :
1373 216691447 : while (len > 0) {
1374 137376102 : unsigned int lock_mode;
1375 :
1376 : /* Read extent from the source file */
1377 137376102 : nimaps = 1;
1378 137376102 : lock_mode = xfs_ilock_data_map_shared(src);
1379 137376573 : error = xfs_bmapi_read(src, srcoff, len, &imap, &nimaps, 0);
1380 137377080 : xfs_iunlock(src, lock_mode);
1381 137377588 : if (error)
1382 : break;
1383 : /*
1384 : * The caller supposedly flushed all dirty pages in the source
1385 : * file range, which means that writeback should have allocated
1386 : * or deleted all delalloc reservations in that range. If we
1387 : * find one, that's a good sign that something is seriously
1388 : * wrong here.
1389 : */
1390 137377517 : ASSERT(nimaps == 1 && imap.br_startoff == srcoff);
1391 137377517 : if (imap.br_startblock == DELAYSTARTBLOCK) {
1392 0 : ASSERT(imap.br_startblock != DELAYSTARTBLOCK);
1393 0 : error = -EFSCORRUPTED;
1394 0 : break;
1395 : }
1396 :
1397 137377517 : trace_xfs_reflink_remap_extent_src(src, &imap);
1398 :
1399 : /* Remap into the destination file at the given offset. */
1400 137377467 : imap.br_startoff = destoff;
1401 137377467 : error = xfs_reflink_remap_extent(dest, &imap, new_isize);
1402 137376088 : if (error)
1403 : break;
1404 :
1405 136786090 : if (fatal_signal_pending(current)) {
1406 : error = -EINTR;
1407 : break;
1408 : }
1409 :
1410 : /* Advance drange/srange */
1411 136787022 : srcoff += imap.br_blockcount;
1412 136787022 : destoff += imap.br_blockcount;
1413 136787022 : len -= imap.br_blockcount;
1414 136787022 : remapped_len += imap.br_blockcount;
1415 : }
1416 :
1417 79906975 : if (error)
1418 590175 : trace_xfs_reflink_remap_blocks_error(dest, error, _RET_IP_);
1419 79906975 : *remapped = min_t(loff_t, remap_len,
1420 : XFS_FSB_TO_B(src->i_mount, remapped_len));
1421 79906975 : return error;
1422 : }
1423 :
1424 : /*
1425 : * If we're reflinking to a point past the destination file's EOF, we must
1426 : * zero any speculative post-EOF preallocations that sit between the old EOF
1427 : * and the destination file offset.
1428 : */
1429 : static int
1430 79906856 : xfs_reflink_zero_posteof(
1431 : struct xfs_inode *ip,
1432 : loff_t pos)
1433 : {
1434 79906856 : loff_t isize = i_size_read(VFS_I(ip));
1435 :
1436 79906856 : if (pos <= isize)
1437 : return 0;
1438 :
1439 1515061 : trace_xfs_zero_eof(ip, isize, pos - isize);
1440 1515061 : return xfs_zero_range(ip, isize, pos - isize, NULL);
1441 : }
1442 :
1443 : /*
1444 : * Prepare two files for range cloning. Upon a successful return both inodes
1445 : * will have the iolock and mmaplock held, the page cache of the out file will
1446 : * be truncated, and any leases on the out file will have been broken. This
1447 : * function borrows heavily from xfs_file_aio_write_checks.
1448 : *
1449 : * The VFS allows partial EOF blocks to "match" for dedupe even though it hasn't
1450 : * checked that the bytes beyond EOF physically match. Hence we cannot use the
1451 : * EOF block in the source dedupe range because it's not a complete block match,
1452 : * hence can introduce a corruption into the file that has it's block replaced.
1453 : *
1454 : * In similar fashion, the VFS file cloning also allows partial EOF blocks to be
1455 : * "block aligned" for the purposes of cloning entire files. However, if the
1456 : * source file range includes the EOF block and it lands within the existing EOF
1457 : * of the destination file, then we can expose stale data from beyond the source
1458 : * file EOF in the destination file.
1459 : *
1460 : * XFS doesn't support partial block sharing, so in both cases we have check
1461 : * these cases ourselves. For dedupe, we can simply round the length to dedupe
1462 : * down to the previous whole block and ignore the partial EOF block. While this
1463 : * means we can't dedupe the last block of a file, this is an acceptible
1464 : * tradeoff for simplicity on implementation.
1465 : *
1466 : * For cloning, we want to share the partial EOF block if it is also the new EOF
1467 : * block of the destination file. If the partial EOF block lies inside the
1468 : * existing destination EOF, then we have to abort the clone to avoid exposing
1469 : * stale data in the destination file. Hence we reject these clone attempts with
1470 : * -EINVAL in this case.
1471 : */
1472 : int
1473 104024076 : xfs_reflink_remap_prep(
1474 : struct file *file_in,
1475 : loff_t pos_in,
1476 : struct file *file_out,
1477 : loff_t pos_out,
1478 : loff_t *len,
1479 : unsigned int remap_flags)
1480 : {
1481 104024076 : struct inode *inode_in = file_inode(file_in);
1482 104024076 : struct xfs_inode *src = XFS_I(inode_in);
1483 104024076 : struct inode *inode_out = file_inode(file_out);
1484 104024076 : struct xfs_inode *dest = XFS_I(inode_out);
1485 104024076 : int ret;
1486 :
1487 : /* Lock both files against IO */
1488 104024076 : ret = xfs_ilock2_io_mmap(src, dest);
1489 104027871 : if (ret)
1490 : return ret;
1491 :
1492 : /* Check file eligibility and prepare for block sharing. */
1493 104027871 : ret = -EINVAL;
1494 : /* Don't reflink realtime inodes */
1495 104027871 : if (XFS_IS_REALTIME_INODE(src) || XFS_IS_REALTIME_INODE(dest))
1496 0 : goto out_unlock;
1497 :
1498 : /* Don't share DAX file data with non-DAX file. */
1499 104027871 : if (IS_DAX(inode_in) != IS_DAX(inode_out))
1500 : goto out_unlock;
1501 :
1502 104027871 : if (!IS_DAX(inode_in))
1503 104027871 : ret = generic_remap_file_range_prep(file_in, pos_in, file_out,
1504 : pos_out, len, remap_flags);
1505 : else
1506 : ret = dax_remap_file_range_prep(file_in, pos_in, file_out,
1507 : pos_out, len, remap_flags, &xfs_read_iomap_ops);
1508 104028117 : if (ret || *len == 0)
1509 24119775 : goto out_unlock;
1510 :
1511 : /* Attach dquots to dest inode before changing block map */
1512 79908342 : ret = xfs_qm_dqattach(dest);
1513 79906559 : if (ret)
1514 0 : goto out_unlock;
1515 :
1516 : /*
1517 : * Zero existing post-eof speculative preallocations in the destination
1518 : * file.
1519 : */
1520 79906559 : ret = xfs_reflink_zero_posteof(dest, pos_out);
1521 79907491 : if (ret)
1522 211 : goto out_unlock;
1523 :
1524 : /* Set flags and remap blocks. */
1525 79907280 : ret = xfs_reflink_set_inode_flag(src, dest);
1526 79906858 : if (ret)
1527 1 : goto out_unlock;
1528 :
1529 : /*
1530 : * If pos_out > EOF, we may have dirtied blocks between EOF and
1531 : * pos_out. In that case, we need to extend the flush and unmap to cover
1532 : * from EOF to the end of the copy length.
1533 : */
1534 159813714 : if (pos_out > XFS_ISIZE(dest)) {
1535 1513560 : loff_t flen = *len + (pos_out - XFS_ISIZE(dest));
1536 1513560 : ret = xfs_flush_unmap_range(dest, XFS_ISIZE(dest), flen);
1537 : } else {
1538 78393297 : ret = xfs_flush_unmap_range(dest, pos_out, *len);
1539 : }
1540 79906981 : if (ret)
1541 945 : goto out_unlock;
1542 :
1543 : return 0;
1544 24120932 : out_unlock:
1545 24120932 : xfs_iunlock2_io_mmap(src, dest);
1546 24120932 : return ret;
1547 : }
1548 :
1549 : /* Does this inode need the reflink flag? */
1550 : int
1551 42401752 : xfs_reflink_inode_has_shared_extents(
1552 : struct xfs_trans *tp,
1553 : struct xfs_inode *ip,
1554 : bool *has_shared)
1555 : {
1556 42401752 : struct xfs_bmbt_irec got;
1557 42401752 : struct xfs_mount *mp = ip->i_mount;
1558 42401752 : struct xfs_ifork *ifp;
1559 42401752 : struct xfs_iext_cursor icur;
1560 42401752 : bool found;
1561 42401752 : int error;
1562 :
1563 42401752 : ifp = xfs_ifork_ptr(ip, XFS_DATA_FORK);
1564 42401752 : error = xfs_iread_extents(tp, ip, XFS_DATA_FORK);
1565 42402124 : if (error)
1566 : return error;
1567 :
1568 42402133 : *has_shared = false;
1569 42402133 : found = xfs_iext_lookup_extent(ip, ifp, 0, &icur, &got);
1570 290890698 : while (found) {
1571 249389291 : struct xfs_perag *pag;
1572 249389291 : xfs_agblock_t agbno;
1573 249389291 : xfs_extlen_t aglen;
1574 249389291 : xfs_agblock_t rbno;
1575 249389291 : xfs_extlen_t rlen;
1576 :
1577 249389291 : if (isnullstartblock(got.br_startblock) ||
1578 249361119 : got.br_state != XFS_EXT_NORM)
1579 10116672 : goto next;
1580 :
1581 239272619 : pag = xfs_perag_get(mp, XFS_FSB_TO_AGNO(mp, got.br_startblock));
1582 239273841 : agbno = XFS_FSB_TO_AGBNO(mp, got.br_startblock);
1583 239274452 : aglen = got.br_blockcount;
1584 239274452 : error = xfs_reflink_find_shared(pag, tp, agbno, aglen,
1585 : &rbno, &rlen, false);
1586 239277245 : xfs_perag_put(pag);
1587 239277306 : if (error)
1588 898541 : return error;
1589 :
1590 : /* Is there still a shared block here? */
1591 239277306 : if (rbno != NULLAGBLOCK) {
1592 898541 : *has_shared = true;
1593 898541 : return 0;
1594 : }
1595 238378765 : next:
1596 248495437 : found = xfs_iext_next_extent(ifp, &icur, &got);
1597 : }
1598 :
1599 : return 0;
1600 : }
1601 :
1602 : /*
1603 : * Clear the inode reflink flag if there are no shared extents.
1604 : *
1605 : * The caller is responsible for joining the inode to the transaction passed in.
1606 : * The inode will be joined to the transaction that is returned to the caller.
1607 : */
1608 : int
1609 38 : xfs_reflink_clear_inode_flag(
1610 : struct xfs_inode *ip,
1611 : struct xfs_trans **tpp)
1612 : {
1613 38 : bool needs_flag;
1614 38 : int error = 0;
1615 :
1616 38 : ASSERT(xfs_is_reflink_inode(ip));
1617 :
1618 38 : error = xfs_reflink_inode_has_shared_extents(*tpp, ip, &needs_flag);
1619 38 : if (error || needs_flag)
1620 26 : return error;
1621 :
1622 : /*
1623 : * We didn't find any shared blocks so turn off the reflink flag.
1624 : * First, get rid of any leftover CoW mappings.
1625 : */
1626 12 : error = xfs_reflink_cancel_cow_blocks(ip, tpp, 0, XFS_MAX_FILEOFF,
1627 : true);
1628 12 : if (error)
1629 : return error;
1630 :
1631 : /* Clear the inode flag. */
1632 12 : trace_xfs_reflink_unset_inode_flag(ip);
1633 12 : ip->i_diflags2 &= ~XFS_DIFLAG2_REFLINK;
1634 12 : xfs_inode_clear_cowblocks_tag(ip);
1635 12 : xfs_trans_log_inode(*tpp, ip, XFS_ILOG_CORE);
1636 :
1637 12 : return error;
1638 : }
1639 :
1640 : /*
1641 : * Clear the inode reflink flag if there are no shared extents and the size
1642 : * hasn't changed.
1643 : */
1644 : STATIC int
1645 38 : xfs_reflink_try_clear_inode_flag(
1646 : struct xfs_inode *ip)
1647 : {
1648 38 : struct xfs_mount *mp = ip->i_mount;
1649 38 : struct xfs_trans *tp;
1650 38 : int error = 0;
1651 :
1652 : /* Start a rolling transaction to remove the mappings */
1653 38 : error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0, 0, &tp);
1654 38 : if (error)
1655 : return error;
1656 :
1657 38 : xfs_ilock(ip, XFS_ILOCK_EXCL);
1658 38 : xfs_trans_ijoin(tp, ip, 0);
1659 :
1660 38 : error = xfs_reflink_clear_inode_flag(ip, &tp);
1661 38 : if (error)
1662 0 : goto cancel;
1663 :
1664 38 : error = xfs_trans_commit(tp);
1665 38 : if (error)
1666 0 : goto out;
1667 :
1668 38 : xfs_iunlock(ip, XFS_ILOCK_EXCL);
1669 38 : return 0;
1670 : cancel:
1671 0 : xfs_trans_cancel(tp);
1672 0 : out:
1673 0 : xfs_iunlock(ip, XFS_ILOCK_EXCL);
1674 0 : return error;
1675 : }
1676 :
1677 : /*
1678 : * Pre-COW all shared blocks within a given byte range of a file and turn off
1679 : * the reflink flag if we unshare all of the file's blocks.
1680 : */
1681 : int
1682 66 : xfs_reflink_unshare(
1683 : struct xfs_inode *ip,
1684 : xfs_off_t offset,
1685 : xfs_off_t len)
1686 : {
1687 66 : struct inode *inode = VFS_I(ip);
1688 66 : int error;
1689 :
1690 66 : if (!xfs_is_reflink_inode(ip))
1691 : return 0;
1692 :
1693 40 : trace_xfs_reflink_unshare(ip, offset, len);
1694 :
1695 40 : inode_dio_wait(inode);
1696 :
1697 40 : if (IS_DAX(inode))
1698 : error = dax_file_unshare(inode, offset, len,
1699 : &xfs_dax_write_iomap_ops);
1700 : else
1701 40 : error = iomap_file_unshare(inode, offset, len,
1702 : &xfs_buffered_write_iomap_ops);
1703 40 : if (error)
1704 0 : goto out;
1705 :
1706 40 : error = filemap_write_and_wait_range(inode->i_mapping, offset,
1707 40 : offset + len - 1);
1708 40 : if (error)
1709 2 : goto out;
1710 :
1711 : /* Turn off the reflink flag if possible. */
1712 38 : error = xfs_reflink_try_clear_inode_flag(ip);
1713 38 : if (error)
1714 0 : goto out;
1715 : return 0;
1716 :
1717 2 : out:
1718 2 : trace_xfs_reflink_unshare_error(ip, error, _RET_IP_);
1719 2 : return error;
1720 : }
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