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1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Copyright (C) 2016 Oracle. All Rights Reserved.
4 * Author: Darrick J. Wong <darrick.wong@oracle.com>
5 */
6#include "xfs.h"
7#include "xfs_fs.h"
8#include "xfs_shared.h"
9#include "xfs_format.h"
10#include "xfs_log_format.h"
11#include "xfs_trans_resv.h"
12#include "xfs_mount.h"
13#include "xfs_defer.h"
14#include "xfs_btree.h"
15#include "xfs_bmap.h"
16#include "xfs_refcount_btree.h"
17#include "xfs_alloc.h"
18#include "xfs_errortag.h"
19#include "xfs_error.h"
20#include "xfs_trace.h"
21#include "xfs_trans.h"
22#include "xfs_bit.h"
23#include "xfs_refcount.h"
24#include "xfs_rmap.h"
25
26/* Allowable refcount adjustment amounts. */
27enum xfs_refc_adjust_op {
28 XFS_REFCOUNT_ADJUST_INCREASE = 1,
29 XFS_REFCOUNT_ADJUST_DECREASE = -1,
30 XFS_REFCOUNT_ADJUST_COW_ALLOC = 0,
31 XFS_REFCOUNT_ADJUST_COW_FREE = -1,
32};
33
34STATIC int __xfs_refcount_cow_alloc(struct xfs_btree_cur *rcur,
35 xfs_agblock_t agbno, xfs_extlen_t aglen);
36STATIC int __xfs_refcount_cow_free(struct xfs_btree_cur *rcur,
37 xfs_agblock_t agbno, xfs_extlen_t aglen);
38
39/*
40 * Look up the first record less than or equal to [bno, len] in the btree
41 * given by cur.
42 */
43int
44xfs_refcount_lookup_le(
45 struct xfs_btree_cur *cur,
46 xfs_agblock_t bno,
47 int *stat)
48{
49 trace_xfs_refcount_lookup(cur->bc_mp, cur->bc_ag.agno, bno,
50 XFS_LOOKUP_LE);
51 cur->bc_rec.rc.rc_startblock = bno;
52 cur->bc_rec.rc.rc_blockcount = 0;
53 return xfs_btree_lookup(cur, XFS_LOOKUP_LE, stat);
54}
55
56/*
57 * Look up the first record greater than or equal to [bno, len] in the btree
58 * given by cur.
59 */
60int
61xfs_refcount_lookup_ge(
62 struct xfs_btree_cur *cur,
63 xfs_agblock_t bno,
64 int *stat)
65{
66 trace_xfs_refcount_lookup(cur->bc_mp, cur->bc_ag.agno, bno,
67 XFS_LOOKUP_GE);
68 cur->bc_rec.rc.rc_startblock = bno;
69 cur->bc_rec.rc.rc_blockcount = 0;
70 return xfs_btree_lookup(cur, XFS_LOOKUP_GE, stat);
71}
72
73/*
74 * Look up the first record equal to [bno, len] in the btree
75 * given by cur.
76 */
77int
78xfs_refcount_lookup_eq(
79 struct xfs_btree_cur *cur,
80 xfs_agblock_t bno,
81 int *stat)
82{
83 trace_xfs_refcount_lookup(cur->bc_mp, cur->bc_ag.agno, bno,
84 XFS_LOOKUP_LE);
85 cur->bc_rec.rc.rc_startblock = bno;
86 cur->bc_rec.rc.rc_blockcount = 0;
87 return xfs_btree_lookup(cur, XFS_LOOKUP_EQ, stat);
88}
89
90/* Convert on-disk record to in-core format. */
91void
92xfs_refcount_btrec_to_irec(
93 union xfs_btree_rec *rec,
94 struct xfs_refcount_irec *irec)
95{
96 irec->rc_startblock = be32_to_cpu(rec->refc.rc_startblock);
97 irec->rc_blockcount = be32_to_cpu(rec->refc.rc_blockcount);
98 irec->rc_refcount = be32_to_cpu(rec->refc.rc_refcount);
99}
100
101/*
102 * Get the data from the pointed-to record.
103 */
104int
105xfs_refcount_get_rec(
106 struct xfs_btree_cur *cur,
107 struct xfs_refcount_irec *irec,
108 int *stat)
109{
110 struct xfs_mount *mp = cur->bc_mp;
111 xfs_agnumber_t agno = cur->bc_ag.agno;
112 union xfs_btree_rec *rec;
113 int error;
114 xfs_agblock_t realstart;
115
116 error = xfs_btree_get_rec(cur, &rec, stat);
117 if (error || !*stat)
118 return error;
119
120 xfs_refcount_btrec_to_irec(rec, irec);
121
122 agno = cur->bc_ag.agno;
123 if (irec->rc_blockcount == 0 || irec->rc_blockcount > MAXREFCEXTLEN)
124 goto out_bad_rec;
125
126 /* handle special COW-staging state */
127 realstart = irec->rc_startblock;
128 if (realstart & XFS_REFC_COW_START) {
129 if (irec->rc_refcount != 1)
130 goto out_bad_rec;
131 realstart &= ~XFS_REFC_COW_START;
132 } else if (irec->rc_refcount < 2) {
133 goto out_bad_rec;
134 }
135
136 /* check for valid extent range, including overflow */
137 if (!xfs_verify_agbno(mp, agno, realstart))
138 goto out_bad_rec;
139 if (realstart > realstart + irec->rc_blockcount)
140 goto out_bad_rec;
141 if (!xfs_verify_agbno(mp, agno, realstart + irec->rc_blockcount - 1))
142 goto out_bad_rec;
143
144 if (irec->rc_refcount == 0 || irec->rc_refcount > MAXREFCOUNT)
145 goto out_bad_rec;
146
147 trace_xfs_refcount_get(cur->bc_mp, cur->bc_ag.agno, irec);
148 return 0;
149
150out_bad_rec:
151 xfs_warn(mp,
152 "Refcount BTree record corruption in AG %d detected!", agno);
153 xfs_warn(mp,
154 "Start block 0x%x, block count 0x%x, references 0x%x",
155 irec->rc_startblock, irec->rc_blockcount, irec->rc_refcount);
156 return -EFSCORRUPTED;
157}
158
159/*
160 * Update the record referred to by cur to the value given
161 * by [bno, len, refcount].
162 * This either works (return 0) or gets an EFSCORRUPTED error.
163 */
164STATIC int
165xfs_refcount_update(
166 struct xfs_btree_cur *cur,
167 struct xfs_refcount_irec *irec)
168{
169 union xfs_btree_rec rec;
170 int error;
171
172 trace_xfs_refcount_update(cur->bc_mp, cur->bc_ag.agno, irec);
173 rec.refc.rc_startblock = cpu_to_be32(irec->rc_startblock);
174 rec.refc.rc_blockcount = cpu_to_be32(irec->rc_blockcount);
175 rec.refc.rc_refcount = cpu_to_be32(irec->rc_refcount);
176 error = xfs_btree_update(cur, &rec);
177 if (error)
178 trace_xfs_refcount_update_error(cur->bc_mp,
179 cur->bc_ag.agno, error, _RET_IP_);
180 return error;
181}
182
183/*
184 * Insert the record referred to by cur to the value given
185 * by [bno, len, refcount].
186 * This either works (return 0) or gets an EFSCORRUPTED error.
187 */
188int
189xfs_refcount_insert(
190 struct xfs_btree_cur *cur,
191 struct xfs_refcount_irec *irec,
192 int *i)
193{
194 int error;
195
196 trace_xfs_refcount_insert(cur->bc_mp, cur->bc_ag.agno, irec);
197 cur->bc_rec.rc.rc_startblock = irec->rc_startblock;
198 cur->bc_rec.rc.rc_blockcount = irec->rc_blockcount;
199 cur->bc_rec.rc.rc_refcount = irec->rc_refcount;
200 error = xfs_btree_insert(cur, i);
201 if (error)
202 goto out_error;
203 if (XFS_IS_CORRUPT(cur->bc_mp, *i != 1)) {
204 error = -EFSCORRUPTED;
205 goto out_error;
206 }
207
208out_error:
209 if (error)
210 trace_xfs_refcount_insert_error(cur->bc_mp,
211 cur->bc_ag.agno, error, _RET_IP_);
212 return error;
213}
214
215/*
216 * Remove the record referred to by cur, then set the pointer to the spot
217 * where the record could be re-inserted, in case we want to increment or
218 * decrement the cursor.
219 * This either works (return 0) or gets an EFSCORRUPTED error.
220 */
221STATIC int
222xfs_refcount_delete(
223 struct xfs_btree_cur *cur,
224 int *i)
225{
226 struct xfs_refcount_irec irec;
227 int found_rec;
228 int error;
229
230 error = xfs_refcount_get_rec(cur, &irec, &found_rec);
231 if (error)
232 goto out_error;
233 if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
234 error = -EFSCORRUPTED;
235 goto out_error;
236 }
237 trace_xfs_refcount_delete(cur->bc_mp, cur->bc_ag.agno, &irec);
238 error = xfs_btree_delete(cur, i);
239 if (XFS_IS_CORRUPT(cur->bc_mp, *i != 1)) {
240 error = -EFSCORRUPTED;
241 goto out_error;
242 }
243 if (error)
244 goto out_error;
245 error = xfs_refcount_lookup_ge(cur, irec.rc_startblock, &found_rec);
246out_error:
247 if (error)
248 trace_xfs_refcount_delete_error(cur->bc_mp,
249 cur->bc_ag.agno, error, _RET_IP_);
250 return error;
251}
252
253/*
254 * Adjusting the Reference Count
255 *
256 * As stated elsewhere, the reference count btree (refcbt) stores
257 * >1 reference counts for extents of physical blocks. In this
258 * operation, we're either raising or lowering the reference count of
259 * some subrange stored in the tree:
260 *
261 * <------ adjustment range ------>
262 * ----+ +---+-----+ +--+--------+---------
263 * 2 | | 3 | 4 | |17| 55 | 10
264 * ----+ +---+-----+ +--+--------+---------
265 * X axis is physical blocks number;
266 * reference counts are the numbers inside the rectangles
267 *
268 * The first thing we need to do is to ensure that there are no
269 * refcount extents crossing either boundary of the range to be
270 * adjusted. For any extent that does cross a boundary, split it into
271 * two extents so that we can increment the refcount of one of the
272 * pieces later:
273 *
274 * <------ adjustment range ------>
275 * ----+ +---+-----+ +--+--------+----+----
276 * 2 | | 3 | 2 | |17| 55 | 10 | 10
277 * ----+ +---+-----+ +--+--------+----+----
278 *
279 * For this next step, let's assume that all the physical blocks in
280 * the adjustment range are mapped to a file and are therefore in use
281 * at least once. Therefore, we can infer that any gap in the
282 * refcount tree within the adjustment range represents a physical
283 * extent with refcount == 1:
284 *
285 * <------ adjustment range ------>
286 * ----+---+---+-----+-+--+--------+----+----
287 * 2 |"1"| 3 | 2 |1|17| 55 | 10 | 10
288 * ----+---+---+-----+-+--+--------+----+----
289 * ^
290 *
291 * For each extent that falls within the interval range, figure out
292 * which extent is to the left or the right of that extent. Now we
293 * have a left, current, and right extent. If the new reference count
294 * of the center extent enables us to merge left, center, and right
295 * into one record covering all three, do so. If the center extent is
296 * at the left end of the range, abuts the left extent, and its new
297 * reference count matches the left extent's record, then merge them.
298 * If the center extent is at the right end of the range, abuts the
299 * right extent, and the reference counts match, merge those. In the
300 * example, we can left merge (assuming an increment operation):
301 *
302 * <------ adjustment range ------>
303 * --------+---+-----+-+--+--------+----+----
304 * 2 | 3 | 2 |1|17| 55 | 10 | 10
305 * --------+---+-----+-+--+--------+----+----
306 * ^
307 *
308 * For all other extents within the range, adjust the reference count
309 * or delete it if the refcount falls below 2. If we were
310 * incrementing, the end result looks like this:
311 *
312 * <------ adjustment range ------>
313 * --------+---+-----+-+--+--------+----+----
314 * 2 | 4 | 3 |2|18| 56 | 11 | 10
315 * --------+---+-----+-+--+--------+----+----
316 *
317 * The result of a decrement operation looks as such:
318 *
319 * <------ adjustment range ------>
320 * ----+ +---+ +--+--------+----+----
321 * 2 | | 2 | |16| 54 | 9 | 10
322 * ----+ +---+ +--+--------+----+----
323 * DDDD 111111DD
324 *
325 * The blocks marked "D" are freed; the blocks marked "1" are only
326 * referenced once and therefore the record is removed from the
327 * refcount btree.
328 */
329
330/* Next block after this extent. */
331static inline xfs_agblock_t
332xfs_refc_next(
333 struct xfs_refcount_irec *rc)
334{
335 return rc->rc_startblock + rc->rc_blockcount;
336}
337
338/*
339 * Split a refcount extent that crosses agbno.
340 */
341STATIC int
342xfs_refcount_split_extent(
343 struct xfs_btree_cur *cur,
344 xfs_agblock_t agbno,
345 bool *shape_changed)
346{
347 struct xfs_refcount_irec rcext, tmp;
348 int found_rec;
349 int error;
350
351 *shape_changed = false;
352 error = xfs_refcount_lookup_le(cur, agbno, &found_rec);
353 if (error)
354 goto out_error;
355 if (!found_rec)
356 return 0;
357
358 error = xfs_refcount_get_rec(cur, &rcext, &found_rec);
359 if (error)
360 goto out_error;
361 if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
362 error = -EFSCORRUPTED;
363 goto out_error;
364 }
365 if (rcext.rc_startblock == agbno || xfs_refc_next(&rcext) <= agbno)
366 return 0;
367
368 *shape_changed = true;
369 trace_xfs_refcount_split_extent(cur->bc_mp, cur->bc_ag.agno,
370 &rcext, agbno);
371
372 /* Establish the right extent. */
373 tmp = rcext;
374 tmp.rc_startblock = agbno;
375 tmp.rc_blockcount -= (agbno - rcext.rc_startblock);
376 error = xfs_refcount_update(cur, &tmp);
377 if (error)
378 goto out_error;
379
380 /* Insert the left extent. */
381 tmp = rcext;
382 tmp.rc_blockcount = agbno - rcext.rc_startblock;
383 error = xfs_refcount_insert(cur, &tmp, &found_rec);
384 if (error)
385 goto out_error;
386 if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
387 error = -EFSCORRUPTED;
388 goto out_error;
389 }
390 return error;
391
392out_error:
393 trace_xfs_refcount_split_extent_error(cur->bc_mp,
394 cur->bc_ag.agno, error, _RET_IP_);
395 return error;
396}
397
398/*
399 * Merge the left, center, and right extents.
400 */
401STATIC int
402xfs_refcount_merge_center_extents(
403 struct xfs_btree_cur *cur,
404 struct xfs_refcount_irec *left,
405 struct xfs_refcount_irec *center,
406 struct xfs_refcount_irec *right,
407 unsigned long long extlen,
408 xfs_extlen_t *aglen)
409{
410 int error;
411 int found_rec;
412
413 trace_xfs_refcount_merge_center_extents(cur->bc_mp,
414 cur->bc_ag.agno, left, center, right);
415
416 /*
417 * Make sure the center and right extents are not in the btree.
418 * If the center extent was synthesized, the first delete call
419 * removes the right extent and we skip the second deletion.
420 * If center and right were in the btree, then the first delete
421 * call removes the center and the second one removes the right
422 * extent.
423 */
424 error = xfs_refcount_lookup_ge(cur, center->rc_startblock,
425 &found_rec);
426 if (error)
427 goto out_error;
428 if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
429 error = -EFSCORRUPTED;
430 goto out_error;
431 }
432
433 error = xfs_refcount_delete(cur, &found_rec);
434 if (error)
435 goto out_error;
436 if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
437 error = -EFSCORRUPTED;
438 goto out_error;
439 }
440
441 if (center->rc_refcount > 1) {
442 error = xfs_refcount_delete(cur, &found_rec);
443 if (error)
444 goto out_error;
445 if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
446 error = -EFSCORRUPTED;
447 goto out_error;
448 }
449 }
450
451 /* Enlarge the left extent. */
452 error = xfs_refcount_lookup_le(cur, left->rc_startblock,
453 &found_rec);
454 if (error)
455 goto out_error;
456 if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
457 error = -EFSCORRUPTED;
458 goto out_error;
459 }
460
461 left->rc_blockcount = extlen;
462 error = xfs_refcount_update(cur, left);
463 if (error)
464 goto out_error;
465
466 *aglen = 0;
467 return error;
468
469out_error:
470 trace_xfs_refcount_merge_center_extents_error(cur->bc_mp,
471 cur->bc_ag.agno, error, _RET_IP_);
472 return error;
473}
474
475/*
476 * Merge with the left extent.
477 */
478STATIC int
479xfs_refcount_merge_left_extent(
480 struct xfs_btree_cur *cur,
481 struct xfs_refcount_irec *left,
482 struct xfs_refcount_irec *cleft,
483 xfs_agblock_t *agbno,
484 xfs_extlen_t *aglen)
485{
486 int error;
487 int found_rec;
488
489 trace_xfs_refcount_merge_left_extent(cur->bc_mp,
490 cur->bc_ag.agno, left, cleft);
491
492 /* If the extent at agbno (cleft) wasn't synthesized, remove it. */
493 if (cleft->rc_refcount > 1) {
494 error = xfs_refcount_lookup_le(cur, cleft->rc_startblock,
495 &found_rec);
496 if (error)
497 goto out_error;
498 if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
499 error = -EFSCORRUPTED;
500 goto out_error;
501 }
502
503 error = xfs_refcount_delete(cur, &found_rec);
504 if (error)
505 goto out_error;
506 if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
507 error = -EFSCORRUPTED;
508 goto out_error;
509 }
510 }
511
512 /* Enlarge the left extent. */
513 error = xfs_refcount_lookup_le(cur, left->rc_startblock,
514 &found_rec);
515 if (error)
516 goto out_error;
517 if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
518 error = -EFSCORRUPTED;
519 goto out_error;
520 }
521
522 left->rc_blockcount += cleft->rc_blockcount;
523 error = xfs_refcount_update(cur, left);
524 if (error)
525 goto out_error;
526
527 *agbno += cleft->rc_blockcount;
528 *aglen -= cleft->rc_blockcount;
529 return error;
530
531out_error:
532 trace_xfs_refcount_merge_left_extent_error(cur->bc_mp,
533 cur->bc_ag.agno, error, _RET_IP_);
534 return error;
535}
536
537/*
538 * Merge with the right extent.
539 */
540STATIC int
541xfs_refcount_merge_right_extent(
542 struct xfs_btree_cur *cur,
543 struct xfs_refcount_irec *right,
544 struct xfs_refcount_irec *cright,
545 xfs_extlen_t *aglen)
546{
547 int error;
548 int found_rec;
549
550 trace_xfs_refcount_merge_right_extent(cur->bc_mp,
551 cur->bc_ag.agno, cright, right);
552
553 /*
554 * If the extent ending at agbno+aglen (cright) wasn't synthesized,
555 * remove it.
556 */
557 if (cright->rc_refcount > 1) {
558 error = xfs_refcount_lookup_le(cur, cright->rc_startblock,
559 &found_rec);
560 if (error)
561 goto out_error;
562 if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
563 error = -EFSCORRUPTED;
564 goto out_error;
565 }
566
567 error = xfs_refcount_delete(cur, &found_rec);
568 if (error)
569 goto out_error;
570 if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
571 error = -EFSCORRUPTED;
572 goto out_error;
573 }
574 }
575
576 /* Enlarge the right extent. */
577 error = xfs_refcount_lookup_le(cur, right->rc_startblock,
578 &found_rec);
579 if (error)
580 goto out_error;
581 if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
582 error = -EFSCORRUPTED;
583 goto out_error;
584 }
585
586 right->rc_startblock -= cright->rc_blockcount;
587 right->rc_blockcount += cright->rc_blockcount;
588 error = xfs_refcount_update(cur, right);
589 if (error)
590 goto out_error;
591
592 *aglen -= cright->rc_blockcount;
593 return error;
594
595out_error:
596 trace_xfs_refcount_merge_right_extent_error(cur->bc_mp,
597 cur->bc_ag.agno, error, _RET_IP_);
598 return error;
599}
600
601#define XFS_FIND_RCEXT_SHARED 1
602#define XFS_FIND_RCEXT_COW 2
603/*
604 * Find the left extent and the one after it (cleft). This function assumes
605 * that we've already split any extent crossing agbno.
606 */
607STATIC int
608xfs_refcount_find_left_extents(
609 struct xfs_btree_cur *cur,
610 struct xfs_refcount_irec *left,
611 struct xfs_refcount_irec *cleft,
612 xfs_agblock_t agbno,
613 xfs_extlen_t aglen,
614 int flags)
615{
616 struct xfs_refcount_irec tmp;
617 int error;
618 int found_rec;
619
620 left->rc_startblock = cleft->rc_startblock = NULLAGBLOCK;
621 error = xfs_refcount_lookup_le(cur, agbno - 1, &found_rec);
622 if (error)
623 goto out_error;
624 if (!found_rec)
625 return 0;
626
627 error = xfs_refcount_get_rec(cur, &tmp, &found_rec);
628 if (error)
629 goto out_error;
630 if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
631 error = -EFSCORRUPTED;
632 goto out_error;
633 }
634
635 if (xfs_refc_next(&tmp) != agbno)
636 return 0;
637 if ((flags & XFS_FIND_RCEXT_SHARED) && tmp.rc_refcount < 2)
638 return 0;
639 if ((flags & XFS_FIND_RCEXT_COW) && tmp.rc_refcount > 1)
640 return 0;
641 /* We have a left extent; retrieve (or invent) the next right one */
642 *left = tmp;
643
644 error = xfs_btree_increment(cur, 0, &found_rec);
645 if (error)
646 goto out_error;
647 if (found_rec) {
648 error = xfs_refcount_get_rec(cur, &tmp, &found_rec);
649 if (error)
650 goto out_error;
651 if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
652 error = -EFSCORRUPTED;
653 goto out_error;
654 }
655
656 /* if tmp starts at the end of our range, just use that */
657 if (tmp.rc_startblock == agbno)
658 *cleft = tmp;
659 else {
660 /*
661 * There's a gap in the refcntbt at the start of the
662 * range we're interested in (refcount == 1) so
663 * synthesize the implied extent and pass it back.
664 * We assume here that the agbno/aglen range was
665 * passed in from a data fork extent mapping and
666 * therefore is allocated to exactly one owner.
667 */
668 cleft->rc_startblock = agbno;
669 cleft->rc_blockcount = min(aglen,
670 tmp.rc_startblock - agbno);
671 cleft->rc_refcount = 1;
672 }
673 } else {
674 /*
675 * No extents, so pretend that there's one covering the whole
676 * range.
677 */
678 cleft->rc_startblock = agbno;
679 cleft->rc_blockcount = aglen;
680 cleft->rc_refcount = 1;
681 }
682 trace_xfs_refcount_find_left_extent(cur->bc_mp, cur->bc_ag.agno,
683 left, cleft, agbno);
684 return error;
685
686out_error:
687 trace_xfs_refcount_find_left_extent_error(cur->bc_mp,
688 cur->bc_ag.agno, error, _RET_IP_);
689 return error;
690}
691
692/*
693 * Find the right extent and the one before it (cright). This function
694 * assumes that we've already split any extents crossing agbno + aglen.
695 */
696STATIC int
697xfs_refcount_find_right_extents(
698 struct xfs_btree_cur *cur,
699 struct xfs_refcount_irec *right,
700 struct xfs_refcount_irec *cright,
701 xfs_agblock_t agbno,
702 xfs_extlen_t aglen,
703 int flags)
704{
705 struct xfs_refcount_irec tmp;
706 int error;
707 int found_rec;
708
709 right->rc_startblock = cright->rc_startblock = NULLAGBLOCK;
710 error = xfs_refcount_lookup_ge(cur, agbno + aglen, &found_rec);
711 if (error)
712 goto out_error;
713 if (!found_rec)
714 return 0;
715
716 error = xfs_refcount_get_rec(cur, &tmp, &found_rec);
717 if (error)
718 goto out_error;
719 if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
720 error = -EFSCORRUPTED;
721 goto out_error;
722 }
723
724 if (tmp.rc_startblock != agbno + aglen)
725 return 0;
726 if ((flags & XFS_FIND_RCEXT_SHARED) && tmp.rc_refcount < 2)
727 return 0;
728 if ((flags & XFS_FIND_RCEXT_COW) && tmp.rc_refcount > 1)
729 return 0;
730 /* We have a right extent; retrieve (or invent) the next left one */
731 *right = tmp;
732
733 error = xfs_btree_decrement(cur, 0, &found_rec);
734 if (error)
735 goto out_error;
736 if (found_rec) {
737 error = xfs_refcount_get_rec(cur, &tmp, &found_rec);
738 if (error)
739 goto out_error;
740 if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
741 error = -EFSCORRUPTED;
742 goto out_error;
743 }
744
745 /* if tmp ends at the end of our range, just use that */
746 if (xfs_refc_next(&tmp) == agbno + aglen)
747 *cright = tmp;
748 else {
749 /*
750 * There's a gap in the refcntbt at the end of the
751 * range we're interested in (refcount == 1) so
752 * create the implied extent and pass it back.
753 * We assume here that the agbno/aglen range was
754 * passed in from a data fork extent mapping and
755 * therefore is allocated to exactly one owner.
756 */
757 cright->rc_startblock = max(agbno, xfs_refc_next(&tmp));
758 cright->rc_blockcount = right->rc_startblock -
759 cright->rc_startblock;
760 cright->rc_refcount = 1;
761 }
762 } else {
763 /*
764 * No extents, so pretend that there's one covering the whole
765 * range.
766 */
767 cright->rc_startblock = agbno;
768 cright->rc_blockcount = aglen;
769 cright->rc_refcount = 1;
770 }
771 trace_xfs_refcount_find_right_extent(cur->bc_mp, cur->bc_ag.agno,
772 cright, right, agbno + aglen);
773 return error;
774
775out_error:
776 trace_xfs_refcount_find_right_extent_error(cur->bc_mp,
777 cur->bc_ag.agno, error, _RET_IP_);
778 return error;
779}
780
781/* Is this extent valid? */
782static inline bool
783xfs_refc_valid(
784 struct xfs_refcount_irec *rc)
785{
786 return rc->rc_startblock != NULLAGBLOCK;
787}
788
789/*
790 * Try to merge with any extents on the boundaries of the adjustment range.
791 */
792STATIC int
793xfs_refcount_merge_extents(
794 struct xfs_btree_cur *cur,
795 xfs_agblock_t *agbno,
796 xfs_extlen_t *aglen,
797 enum xfs_refc_adjust_op adjust,
798 int flags,
799 bool *shape_changed)
800{
801 struct xfs_refcount_irec left = {0}, cleft = {0};
802 struct xfs_refcount_irec cright = {0}, right = {0};
803 int error;
804 unsigned long long ulen;
805 bool cequal;
806
807 *shape_changed = false;
808 /*
809 * Find the extent just below agbno [left], just above agbno [cleft],
810 * just below (agbno + aglen) [cright], and just above (agbno + aglen)
811 * [right].
812 */
813 error = xfs_refcount_find_left_extents(cur, &left, &cleft, *agbno,
814 *aglen, flags);
815 if (error)
816 return error;
817 error = xfs_refcount_find_right_extents(cur, &right, &cright, *agbno,
818 *aglen, flags);
819 if (error)
820 return error;
821
822 /* No left or right extent to merge; exit. */
823 if (!xfs_refc_valid(&left) && !xfs_refc_valid(&right))
824 return 0;
825
826 cequal = (cleft.rc_startblock == cright.rc_startblock) &&
827 (cleft.rc_blockcount == cright.rc_blockcount);
828
829 /* Try to merge left, cleft, and right. cleft must == cright. */
830 ulen = (unsigned long long)left.rc_blockcount + cleft.rc_blockcount +
831 right.rc_blockcount;
832 if (xfs_refc_valid(&left) && xfs_refc_valid(&right) &&
833 xfs_refc_valid(&cleft) && xfs_refc_valid(&cright) && cequal &&
834 left.rc_refcount == cleft.rc_refcount + adjust &&
835 right.rc_refcount == cleft.rc_refcount + adjust &&
836 ulen < MAXREFCEXTLEN) {
837 *shape_changed = true;
838 return xfs_refcount_merge_center_extents(cur, &left, &cleft,
839 &right, ulen, aglen);
840 }
841
842 /* Try to merge left and cleft. */
843 ulen = (unsigned long long)left.rc_blockcount + cleft.rc_blockcount;
844 if (xfs_refc_valid(&left) && xfs_refc_valid(&cleft) &&
845 left.rc_refcount == cleft.rc_refcount + adjust &&
846 ulen < MAXREFCEXTLEN) {
847 *shape_changed = true;
848 error = xfs_refcount_merge_left_extent(cur, &left, &cleft,
849 agbno, aglen);
850 if (error)
851 return error;
852
853 /*
854 * If we just merged left + cleft and cleft == cright,
855 * we no longer have a cright to merge with right. We're done.
856 */
857 if (cequal)
858 return 0;
859 }
860
861 /* Try to merge cright and right. */
862 ulen = (unsigned long long)right.rc_blockcount + cright.rc_blockcount;
863 if (xfs_refc_valid(&right) && xfs_refc_valid(&cright) &&
864 right.rc_refcount == cright.rc_refcount + adjust &&
865 ulen < MAXREFCEXTLEN) {
866 *shape_changed = true;
867 return xfs_refcount_merge_right_extent(cur, &right, &cright,
868 aglen);
869 }
870
871 return error;
872}
873
874/*
875 * XXX: This is a pretty hand-wavy estimate. The penalty for guessing
876 * true incorrectly is a shutdown FS; the penalty for guessing false
877 * incorrectly is more transaction rolls than might be necessary.
878 * Be conservative here.
879 */
880static bool
881xfs_refcount_still_have_space(
882 struct xfs_btree_cur *cur)
883{
884 unsigned long overhead;
885
886 overhead = cur->bc_ag.refc.shape_changes *
887 xfs_allocfree_log_count(cur->bc_mp, 1);
888 overhead *= cur->bc_mp->m_sb.sb_blocksize;
889
890 /*
891 * Only allow 2 refcount extent updates per transaction if the
892 * refcount continue update "error" has been injected.
893 */
894 if (cur->bc_ag.refc.nr_ops > 2 &&
895 XFS_TEST_ERROR(false, cur->bc_mp,
896 XFS_ERRTAG_REFCOUNT_CONTINUE_UPDATE))
897 return false;
898
899 if (cur->bc_ag.refc.nr_ops == 0)
900 return true;
901 else if (overhead > cur->bc_tp->t_log_res)
902 return false;
903 return cur->bc_tp->t_log_res - overhead >
904 cur->bc_ag.refc.nr_ops * XFS_REFCOUNT_ITEM_OVERHEAD;
905}
906
907/*
908 * Adjust the refcounts of middle extents. At this point we should have
909 * split extents that crossed the adjustment range; merged with adjacent
910 * extents; and updated agbno/aglen to reflect the merges. Therefore,
911 * all we have to do is update the extents inside [agbno, agbno + aglen].
912 */
913STATIC int
914xfs_refcount_adjust_extents(
915 struct xfs_btree_cur *cur,
916 xfs_agblock_t *agbno,
917 xfs_extlen_t *aglen,
918 enum xfs_refc_adjust_op adj,
919 struct xfs_owner_info *oinfo)
920{
921 struct xfs_refcount_irec ext, tmp;
922 int error;
923 int found_rec, found_tmp;
924 xfs_fsblock_t fsbno;
925
926 /* Merging did all the work already. */
927 if (*aglen == 0)
928 return 0;
929
930 error = xfs_refcount_lookup_ge(cur, *agbno, &found_rec);
931 if (error)
932 goto out_error;
933
934 while (*aglen > 0 && xfs_refcount_still_have_space(cur)) {
935 error = xfs_refcount_get_rec(cur, &ext, &found_rec);
936 if (error)
937 goto out_error;
938 if (!found_rec) {
939 ext.rc_startblock = cur->bc_mp->m_sb.sb_agblocks;
940 ext.rc_blockcount = 0;
941 ext.rc_refcount = 0;
942 }
943
944 /*
945 * Deal with a hole in the refcount tree; if a file maps to
946 * these blocks and there's no refcountbt record, pretend that
947 * there is one with refcount == 1.
948 */
949 if (ext.rc_startblock != *agbno) {
950 tmp.rc_startblock = *agbno;
951 tmp.rc_blockcount = min(*aglen,
952 ext.rc_startblock - *agbno);
953 tmp.rc_refcount = 1 + adj;
954 trace_xfs_refcount_modify_extent(cur->bc_mp,
955 cur->bc_ag.agno, &tmp);
956
957 /*
958 * Either cover the hole (increment) or
959 * delete the range (decrement).
960 */
961 if (tmp.rc_refcount) {
962 error = xfs_refcount_insert(cur, &tmp,
963 &found_tmp);
964 if (error)
965 goto out_error;
966 if (XFS_IS_CORRUPT(cur->bc_mp,
967 found_tmp != 1)) {
968 error = -EFSCORRUPTED;
969 goto out_error;
970 }
971 cur->bc_ag.refc.nr_ops++;
972 } else {
973 fsbno = XFS_AGB_TO_FSB(cur->bc_mp,
974 cur->bc_ag.agno,
975 tmp.rc_startblock);
976 xfs_bmap_add_free(cur->bc_tp, fsbno,
977 tmp.rc_blockcount, oinfo);
978 }
979
980 (*agbno) += tmp.rc_blockcount;
981 (*aglen) -= tmp.rc_blockcount;
982
983 error = xfs_refcount_lookup_ge(cur, *agbno,
984 &found_rec);
985 if (error)
986 goto out_error;
987 }
988
989 /* Stop if there's nothing left to modify */
990 if (*aglen == 0 || !xfs_refcount_still_have_space(cur))
991 break;
992
993 /*
994 * Adjust the reference count and either update the tree
995 * (incr) or free the blocks (decr).
996 */
997 if (ext.rc_refcount == MAXREFCOUNT)
998 goto skip;
999 ext.rc_refcount += adj;
1000 trace_xfs_refcount_modify_extent(cur->bc_mp,
1001 cur->bc_ag.agno, &ext);
1002 if (ext.rc_refcount > 1) {
1003 error = xfs_refcount_update(cur, &ext);
1004 if (error)
1005 goto out_error;
1006 cur->bc_ag.refc.nr_ops++;
1007 } else if (ext.rc_refcount == 1) {
1008 error = xfs_refcount_delete(cur, &found_rec);
1009 if (error)
1010 goto out_error;
1011 if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
1012 error = -EFSCORRUPTED;
1013 goto out_error;
1014 }
1015 cur->bc_ag.refc.nr_ops++;
1016 goto advloop;
1017 } else {
1018 fsbno = XFS_AGB_TO_FSB(cur->bc_mp,
1019 cur->bc_ag.agno,
1020 ext.rc_startblock);
1021 xfs_bmap_add_free(cur->bc_tp, fsbno, ext.rc_blockcount,
1022 oinfo);
1023 }
1024
1025skip:
1026 error = xfs_btree_increment(cur, 0, &found_rec);
1027 if (error)
1028 goto out_error;
1029
1030advloop:
1031 (*agbno) += ext.rc_blockcount;
1032 (*aglen) -= ext.rc_blockcount;
1033 }
1034
1035 return error;
1036out_error:
1037 trace_xfs_refcount_modify_extent_error(cur->bc_mp,
1038 cur->bc_ag.agno, error, _RET_IP_);
1039 return error;
1040}
1041
1042/* Adjust the reference count of a range of AG blocks. */
1043STATIC int
1044xfs_refcount_adjust(
1045 struct xfs_btree_cur *cur,
1046 xfs_agblock_t agbno,
1047 xfs_extlen_t aglen,
1048 xfs_agblock_t *new_agbno,
1049 xfs_extlen_t *new_aglen,
1050 enum xfs_refc_adjust_op adj,
1051 struct xfs_owner_info *oinfo)
1052{
1053 bool shape_changed;
1054 int shape_changes = 0;
1055 int error;
1056
1057 *new_agbno = agbno;
1058 *new_aglen = aglen;
1059 if (adj == XFS_REFCOUNT_ADJUST_INCREASE)
1060 trace_xfs_refcount_increase(cur->bc_mp, cur->bc_ag.agno,
1061 agbno, aglen);
1062 else
1063 trace_xfs_refcount_decrease(cur->bc_mp, cur->bc_ag.agno,
1064 agbno, aglen);
1065
1066 /*
1067 * Ensure that no rcextents cross the boundary of the adjustment range.
1068 */
1069 error = xfs_refcount_split_extent(cur, agbno, &shape_changed);
1070 if (error)
1071 goto out_error;
1072 if (shape_changed)
1073 shape_changes++;
1074
1075 error = xfs_refcount_split_extent(cur, agbno + aglen, &shape_changed);
1076 if (error)
1077 goto out_error;
1078 if (shape_changed)
1079 shape_changes++;
1080
1081 /*
1082 * Try to merge with the left or right extents of the range.
1083 */
1084 error = xfs_refcount_merge_extents(cur, new_agbno, new_aglen, adj,
1085 XFS_FIND_RCEXT_SHARED, &shape_changed);
1086 if (error)
1087 goto out_error;
1088 if (shape_changed)
1089 shape_changes++;
1090 if (shape_changes)
1091 cur->bc_ag.refc.shape_changes++;
1092
1093 /* Now that we've taken care of the ends, adjust the middle extents */
1094 error = xfs_refcount_adjust_extents(cur, new_agbno, new_aglen,
1095 adj, oinfo);
1096 if (error)
1097 goto out_error;
1098
1099 return 0;
1100
1101out_error:
1102 trace_xfs_refcount_adjust_error(cur->bc_mp, cur->bc_ag.agno,
1103 error, _RET_IP_);
1104 return error;
1105}
1106
1107/* Clean up after calling xfs_refcount_finish_one. */
1108void
1109xfs_refcount_finish_one_cleanup(
1110 struct xfs_trans *tp,
1111 struct xfs_btree_cur *rcur,
1112 int error)
1113{
1114 struct xfs_buf *agbp;
1115
1116 if (rcur == NULL)
1117 return;
1118 agbp = rcur->bc_ag.agbp;
1119 xfs_btree_del_cursor(rcur, error);
1120 if (error)
1121 xfs_trans_brelse(tp, agbp);
1122}
1123
1124/*
1125 * Process one of the deferred refcount operations. We pass back the
1126 * btree cursor to maintain our lock on the btree between calls.
1127 * This saves time and eliminates a buffer deadlock between the
1128 * superblock and the AGF because we'll always grab them in the same
1129 * order.
1130 */
1131int
1132xfs_refcount_finish_one(
1133 struct xfs_trans *tp,
1134 enum xfs_refcount_intent_type type,
1135 xfs_fsblock_t startblock,
1136 xfs_extlen_t blockcount,
1137 xfs_fsblock_t *new_fsb,
1138 xfs_extlen_t *new_len,
1139 struct xfs_btree_cur **pcur)
1140{
1141 struct xfs_mount *mp = tp->t_mountp;
1142 struct xfs_btree_cur *rcur;
1143 struct xfs_buf *agbp = NULL;
1144 int error = 0;
1145 xfs_agnumber_t agno;
1146 xfs_agblock_t bno;
1147 xfs_agblock_t new_agbno;
1148 unsigned long nr_ops = 0;
1149 int shape_changes = 0;
1150
1151 agno = XFS_FSB_TO_AGNO(mp, startblock);
1152 ASSERT(agno != NULLAGNUMBER);
1153 bno = XFS_FSB_TO_AGBNO(mp, startblock);
1154
1155 trace_xfs_refcount_deferred(mp, XFS_FSB_TO_AGNO(mp, startblock),
1156 type, XFS_FSB_TO_AGBNO(mp, startblock),
1157 blockcount);
1158
1159 if (XFS_TEST_ERROR(false, mp,
1160 XFS_ERRTAG_REFCOUNT_FINISH_ONE))
1161 return -EIO;
1162
1163 /*
1164 * If we haven't gotten a cursor or the cursor AG doesn't match
1165 * the startblock, get one now.
1166 */
1167 rcur = *pcur;
1168 if (rcur != NULL && rcur->bc_ag.agno != agno) {
1169 nr_ops = rcur->bc_ag.refc.nr_ops;
1170 shape_changes = rcur->bc_ag.refc.shape_changes;
1171 xfs_refcount_finish_one_cleanup(tp, rcur, 0);
1172 rcur = NULL;
1173 *pcur = NULL;
1174 }
1175 if (rcur == NULL) {
1176 error = xfs_alloc_read_agf(tp->t_mountp, tp, agno,
1177 XFS_ALLOC_FLAG_FREEING, &agbp);
1178 if (error)
1179 return error;
1180
1181 rcur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno);
1182 if (!rcur) {
1183 error = -ENOMEM;
1184 goto out_cur;
1185 }
1186 rcur->bc_ag.refc.nr_ops = nr_ops;
1187 rcur->bc_ag.refc.shape_changes = shape_changes;
1188 }
1189 *pcur = rcur;
1190
1191 switch (type) {
1192 case XFS_REFCOUNT_INCREASE:
1193 error = xfs_refcount_adjust(rcur, bno, blockcount, &new_agbno,
1194 new_len, XFS_REFCOUNT_ADJUST_INCREASE, NULL);
1195 *new_fsb = XFS_AGB_TO_FSB(mp, agno, new_agbno);
1196 break;
1197 case XFS_REFCOUNT_DECREASE:
1198 error = xfs_refcount_adjust(rcur, bno, blockcount, &new_agbno,
1199 new_len, XFS_REFCOUNT_ADJUST_DECREASE, NULL);
1200 *new_fsb = XFS_AGB_TO_FSB(mp, agno, new_agbno);
1201 break;
1202 case XFS_REFCOUNT_ALLOC_COW:
1203 *new_fsb = startblock + blockcount;
1204 *new_len = 0;
1205 error = __xfs_refcount_cow_alloc(rcur, bno, blockcount);
1206 break;
1207 case XFS_REFCOUNT_FREE_COW:
1208 *new_fsb = startblock + blockcount;
1209 *new_len = 0;
1210 error = __xfs_refcount_cow_free(rcur, bno, blockcount);
1211 break;
1212 default:
1213 ASSERT(0);
1214 error = -EFSCORRUPTED;
1215 }
1216 if (!error && *new_len > 0)
1217 trace_xfs_refcount_finish_one_leftover(mp, agno, type,
1218 bno, blockcount, new_agbno, *new_len);
1219 return error;
1220
1221out_cur:
1222 xfs_trans_brelse(tp, agbp);
1223
1224 return error;
1225}
1226
1227/*
1228 * Record a refcount intent for later processing.
1229 */
1230static void
1231__xfs_refcount_add(
1232 struct xfs_trans *tp,
1233 enum xfs_refcount_intent_type type,
1234 xfs_fsblock_t startblock,
1235 xfs_extlen_t blockcount)
1236{
1237 struct xfs_refcount_intent *ri;
1238
1239 trace_xfs_refcount_defer(tp->t_mountp,
1240 XFS_FSB_TO_AGNO(tp->t_mountp, startblock),
1241 type, XFS_FSB_TO_AGBNO(tp->t_mountp, startblock),
1242 blockcount);
1243
1244 ri = kmem_alloc(sizeof(struct xfs_refcount_intent),
1245 KM_NOFS);
1246 INIT_LIST_HEAD(&ri->ri_list);
1247 ri->ri_type = type;
1248 ri->ri_startblock = startblock;
1249 ri->ri_blockcount = blockcount;
1250
1251 xfs_defer_add(tp, XFS_DEFER_OPS_TYPE_REFCOUNT, &ri->ri_list);
1252}
1253
1254/*
1255 * Increase the reference count of the blocks backing a file's extent.
1256 */
1257void
1258xfs_refcount_increase_extent(
1259 struct xfs_trans *tp,
1260 struct xfs_bmbt_irec *PREV)
1261{
1262 if (!xfs_sb_version_hasreflink(&tp->t_mountp->m_sb))
1263 return;
1264
1265 __xfs_refcount_add(tp, XFS_REFCOUNT_INCREASE, PREV->br_startblock,
1266 PREV->br_blockcount);
1267}
1268
1269/*
1270 * Decrease the reference count of the blocks backing a file's extent.
1271 */
1272void
1273xfs_refcount_decrease_extent(
1274 struct xfs_trans *tp,
1275 struct xfs_bmbt_irec *PREV)
1276{
1277 if (!xfs_sb_version_hasreflink(&tp->t_mountp->m_sb))
1278 return;
1279
1280 __xfs_refcount_add(tp, XFS_REFCOUNT_DECREASE, PREV->br_startblock,
1281 PREV->br_blockcount);
1282}
1283
1284/*
1285 * Given an AG extent, find the lowest-numbered run of shared blocks
1286 * within that range and return the range in fbno/flen. If
1287 * find_end_of_shared is set, return the longest contiguous extent of
1288 * shared blocks; if not, just return the first extent we find. If no
1289 * shared blocks are found, fbno and flen will be set to NULLAGBLOCK
1290 * and 0, respectively.
1291 */
1292int
1293xfs_refcount_find_shared(
1294 struct xfs_btree_cur *cur,
1295 xfs_agblock_t agbno,
1296 xfs_extlen_t aglen,
1297 xfs_agblock_t *fbno,
1298 xfs_extlen_t *flen,
1299 bool find_end_of_shared)
1300{
1301 struct xfs_refcount_irec tmp;
1302 int i;
1303 int have;
1304 int error;
1305
1306 trace_xfs_refcount_find_shared(cur->bc_mp, cur->bc_ag.agno,
1307 agbno, aglen);
1308
1309 /* By default, skip the whole range */
1310 *fbno = NULLAGBLOCK;
1311 *flen = 0;
1312
1313 /* Try to find a refcount extent that crosses the start */
1314 error = xfs_refcount_lookup_le(cur, agbno, &have);
1315 if (error)
1316 goto out_error;
1317 if (!have) {
1318 /* No left extent, look at the next one */
1319 error = xfs_btree_increment(cur, 0, &have);
1320 if (error)
1321 goto out_error;
1322 if (!have)
1323 goto done;
1324 }
1325 error = xfs_refcount_get_rec(cur, &tmp, &i);
1326 if (error)
1327 goto out_error;
1328 if (XFS_IS_CORRUPT(cur->bc_mp, i != 1)) {
1329 error = -EFSCORRUPTED;
1330 goto out_error;
1331 }
1332
1333 /* If the extent ends before the start, look at the next one */
1334 if (tmp.rc_startblock + tmp.rc_blockcount <= agbno) {
1335 error = xfs_btree_increment(cur, 0, &have);
1336 if (error)
1337 goto out_error;
1338 if (!have)
1339 goto done;
1340 error = xfs_refcount_get_rec(cur, &tmp, &i);
1341 if (error)
1342 goto out_error;
1343 if (XFS_IS_CORRUPT(cur->bc_mp, i != 1)) {
1344 error = -EFSCORRUPTED;
1345 goto out_error;
1346 }
1347 }
1348
1349 /* If the extent starts after the range we want, bail out */
1350 if (tmp.rc_startblock >= agbno + aglen)
1351 goto done;
1352
1353 /* We found the start of a shared extent! */
1354 if (tmp.rc_startblock < agbno) {
1355 tmp.rc_blockcount -= (agbno - tmp.rc_startblock);
1356 tmp.rc_startblock = agbno;
1357 }
1358
1359 *fbno = tmp.rc_startblock;
1360 *flen = min(tmp.rc_blockcount, agbno + aglen - *fbno);
1361 if (!find_end_of_shared)
1362 goto done;
1363
1364 /* Otherwise, find the end of this shared extent */
1365 while (*fbno + *flen < agbno + aglen) {
1366 error = xfs_btree_increment(cur, 0, &have);
1367 if (error)
1368 goto out_error;
1369 if (!have)
1370 break;
1371 error = xfs_refcount_get_rec(cur, &tmp, &i);
1372 if (error)
1373 goto out_error;
1374 if (XFS_IS_CORRUPT(cur->bc_mp, i != 1)) {
1375 error = -EFSCORRUPTED;
1376 goto out_error;
1377 }
1378 if (tmp.rc_startblock >= agbno + aglen ||
1379 tmp.rc_startblock != *fbno + *flen)
1380 break;
1381 *flen = min(*flen + tmp.rc_blockcount, agbno + aglen - *fbno);
1382 }
1383
1384done:
1385 trace_xfs_refcount_find_shared_result(cur->bc_mp,
1386 cur->bc_ag.agno, *fbno, *flen);
1387
1388out_error:
1389 if (error)
1390 trace_xfs_refcount_find_shared_error(cur->bc_mp,
1391 cur->bc_ag.agno, error, _RET_IP_);
1392 return error;
1393}
1394
1395/*
1396 * Recovering CoW Blocks After a Crash
1397 *
1398 * Due to the way that the copy on write mechanism works, there's a window of
1399 * opportunity in which we can lose track of allocated blocks during a crash.
1400 * Because CoW uses delayed allocation in the in-core CoW fork, writeback
1401 * causes blocks to be allocated and stored in the CoW fork. The blocks are
1402 * no longer in the free space btree but are not otherwise recorded anywhere
1403 * until the write completes and the blocks are mapped into the file. A crash
1404 * in between allocation and remapping results in the replacement blocks being
1405 * lost. This situation is exacerbated by the CoW extent size hint because
1406 * allocations can hang around for long time.
1407 *
1408 * However, there is a place where we can record these allocations before they
1409 * become mappings -- the reference count btree. The btree does not record
1410 * extents with refcount == 1, so we can record allocations with a refcount of
1411 * 1. Blocks being used for CoW writeout cannot be shared, so there should be
1412 * no conflict with shared block records. These mappings should be created
1413 * when we allocate blocks to the CoW fork and deleted when they're removed
1414 * from the CoW fork.
1415 *
1416 * Minor nit: records for in-progress CoW allocations and records for shared
1417 * extents must never be merged, to preserve the property that (except for CoW
1418 * allocations) there are no refcount btree entries with refcount == 1. The
1419 * only time this could potentially happen is when unsharing a block that's
1420 * adjacent to CoW allocations, so we must be careful to avoid this.
1421 *
1422 * At mount time we recover lost CoW allocations by searching the refcount
1423 * btree for these refcount == 1 mappings. These represent CoW allocations
1424 * that were in progress at the time the filesystem went down, so we can free
1425 * them to get the space back.
1426 *
1427 * This mechanism is superior to creating EFIs for unmapped CoW extents for
1428 * several reasons -- first, EFIs pin the tail of the log and would have to be
1429 * periodically relogged to avoid filling up the log. Second, CoW completions
1430 * will have to file an EFD and create new EFIs for whatever remains in the
1431 * CoW fork; this partially takes care of (1) but extent-size reservations
1432 * will have to periodically relog even if there's no writeout in progress.
1433 * This can happen if the CoW extent size hint is set, which you really want.
1434 * Third, EFIs cannot currently be automatically relogged into newer
1435 * transactions to advance the log tail. Fourth, stuffing the log full of
1436 * EFIs places an upper bound on the number of CoW allocations that can be
1437 * held filesystem-wide at any given time. Recording them in the refcount
1438 * btree doesn't require us to maintain any state in memory and doesn't pin
1439 * the log.
1440 */
1441/*
1442 * Adjust the refcounts of CoW allocations. These allocations are "magic"
1443 * in that they're not referenced anywhere else in the filesystem, so we
1444 * stash them in the refcount btree with a refcount of 1 until either file
1445 * remapping (or CoW cancellation) happens.
1446 */
1447STATIC int
1448xfs_refcount_adjust_cow_extents(
1449 struct xfs_btree_cur *cur,
1450 xfs_agblock_t agbno,
1451 xfs_extlen_t aglen,
1452 enum xfs_refc_adjust_op adj)
1453{
1454 struct xfs_refcount_irec ext, tmp;
1455 int error;
1456 int found_rec, found_tmp;
1457
1458 if (aglen == 0)
1459 return 0;
1460
1461 /* Find any overlapping refcount records */
1462 error = xfs_refcount_lookup_ge(cur, agbno, &found_rec);
1463 if (error)
1464 goto out_error;
1465 error = xfs_refcount_get_rec(cur, &ext, &found_rec);
1466 if (error)
1467 goto out_error;
1468 if (!found_rec) {
1469 ext.rc_startblock = cur->bc_mp->m_sb.sb_agblocks +
1470 XFS_REFC_COW_START;
1471 ext.rc_blockcount = 0;
1472 ext.rc_refcount = 0;
1473 }
1474
1475 switch (adj) {
1476 case XFS_REFCOUNT_ADJUST_COW_ALLOC:
1477 /* Adding a CoW reservation, there should be nothing here. */
1478 if (XFS_IS_CORRUPT(cur->bc_mp,
1479 agbno + aglen > ext.rc_startblock)) {
1480 error = -EFSCORRUPTED;
1481 goto out_error;
1482 }
1483
1484 tmp.rc_startblock = agbno;
1485 tmp.rc_blockcount = aglen;
1486 tmp.rc_refcount = 1;
1487 trace_xfs_refcount_modify_extent(cur->bc_mp,
1488 cur->bc_ag.agno, &tmp);
1489
1490 error = xfs_refcount_insert(cur, &tmp,
1491 &found_tmp);
1492 if (error)
1493 goto out_error;
1494 if (XFS_IS_CORRUPT(cur->bc_mp, found_tmp != 1)) {
1495 error = -EFSCORRUPTED;
1496 goto out_error;
1497 }
1498 break;
1499 case XFS_REFCOUNT_ADJUST_COW_FREE:
1500 /* Removing a CoW reservation, there should be one extent. */
1501 if (XFS_IS_CORRUPT(cur->bc_mp, ext.rc_startblock != agbno)) {
1502 error = -EFSCORRUPTED;
1503 goto out_error;
1504 }
1505 if (XFS_IS_CORRUPT(cur->bc_mp, ext.rc_blockcount != aglen)) {
1506 error = -EFSCORRUPTED;
1507 goto out_error;
1508 }
1509 if (XFS_IS_CORRUPT(cur->bc_mp, ext.rc_refcount != 1)) {
1510 error = -EFSCORRUPTED;
1511 goto out_error;
1512 }
1513
1514 ext.rc_refcount = 0;
1515 trace_xfs_refcount_modify_extent(cur->bc_mp,
1516 cur->bc_ag.agno, &ext);
1517 error = xfs_refcount_delete(cur, &found_rec);
1518 if (error)
1519 goto out_error;
1520 if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
1521 error = -EFSCORRUPTED;
1522 goto out_error;
1523 }
1524 break;
1525 default:
1526 ASSERT(0);
1527 }
1528
1529 return error;
1530out_error:
1531 trace_xfs_refcount_modify_extent_error(cur->bc_mp,
1532 cur->bc_ag.agno, error, _RET_IP_);
1533 return error;
1534}
1535
1536/*
1537 * Add or remove refcount btree entries for CoW reservations.
1538 */
1539STATIC int
1540xfs_refcount_adjust_cow(
1541 struct xfs_btree_cur *cur,
1542 xfs_agblock_t agbno,
1543 xfs_extlen_t aglen,
1544 enum xfs_refc_adjust_op adj)
1545{
1546 bool shape_changed;
1547 int error;
1548
1549 agbno += XFS_REFC_COW_START;
1550
1551 /*
1552 * Ensure that no rcextents cross the boundary of the adjustment range.
1553 */
1554 error = xfs_refcount_split_extent(cur, agbno, &shape_changed);
1555 if (error)
1556 goto out_error;
1557
1558 error = xfs_refcount_split_extent(cur, agbno + aglen, &shape_changed);
1559 if (error)
1560 goto out_error;
1561
1562 /*
1563 * Try to merge with the left or right extents of the range.
1564 */
1565 error = xfs_refcount_merge_extents(cur, &agbno, &aglen, adj,
1566 XFS_FIND_RCEXT_COW, &shape_changed);
1567 if (error)
1568 goto out_error;
1569
1570 /* Now that we've taken care of the ends, adjust the middle extents */
1571 error = xfs_refcount_adjust_cow_extents(cur, agbno, aglen, adj);
1572 if (error)
1573 goto out_error;
1574
1575 return 0;
1576
1577out_error:
1578 trace_xfs_refcount_adjust_cow_error(cur->bc_mp, cur->bc_ag.agno,
1579 error, _RET_IP_);
1580 return error;
1581}
1582
1583/*
1584 * Record a CoW allocation in the refcount btree.
1585 */
1586STATIC int
1587__xfs_refcount_cow_alloc(
1588 struct xfs_btree_cur *rcur,
1589 xfs_agblock_t agbno,
1590 xfs_extlen_t aglen)
1591{
1592 trace_xfs_refcount_cow_increase(rcur->bc_mp, rcur->bc_ag.agno,
1593 agbno, aglen);
1594
1595 /* Add refcount btree reservation */
1596 return xfs_refcount_adjust_cow(rcur, agbno, aglen,
1597 XFS_REFCOUNT_ADJUST_COW_ALLOC);
1598}
1599
1600/*
1601 * Remove a CoW allocation from the refcount btree.
1602 */
1603STATIC int
1604__xfs_refcount_cow_free(
1605 struct xfs_btree_cur *rcur,
1606 xfs_agblock_t agbno,
1607 xfs_extlen_t aglen)
1608{
1609 trace_xfs_refcount_cow_decrease(rcur->bc_mp, rcur->bc_ag.agno,
1610 agbno, aglen);
1611
1612 /* Remove refcount btree reservation */
1613 return xfs_refcount_adjust_cow(rcur, agbno, aglen,
1614 XFS_REFCOUNT_ADJUST_COW_FREE);
1615}
1616
1617/* Record a CoW staging extent in the refcount btree. */
1618void
1619xfs_refcount_alloc_cow_extent(
1620 struct xfs_trans *tp,
1621 xfs_fsblock_t fsb,
1622 xfs_extlen_t len)
1623{
1624 struct xfs_mount *mp = tp->t_mountp;
1625
1626 if (!xfs_sb_version_hasreflink(&mp->m_sb))
1627 return;
1628
1629 __xfs_refcount_add(tp, XFS_REFCOUNT_ALLOC_COW, fsb, len);
1630
1631 /* Add rmap entry */
1632 xfs_rmap_alloc_extent(tp, XFS_FSB_TO_AGNO(mp, fsb),
1633 XFS_FSB_TO_AGBNO(mp, fsb), len, XFS_RMAP_OWN_COW);
1634}
1635
1636/* Forget a CoW staging event in the refcount btree. */
1637void
1638xfs_refcount_free_cow_extent(
1639 struct xfs_trans *tp,
1640 xfs_fsblock_t fsb,
1641 xfs_extlen_t len)
1642{
1643 struct xfs_mount *mp = tp->t_mountp;
1644
1645 if (!xfs_sb_version_hasreflink(&mp->m_sb))
1646 return;
1647
1648 /* Remove rmap entry */
1649 xfs_rmap_free_extent(tp, XFS_FSB_TO_AGNO(mp, fsb),
1650 XFS_FSB_TO_AGBNO(mp, fsb), len, XFS_RMAP_OWN_COW);
1651 __xfs_refcount_add(tp, XFS_REFCOUNT_FREE_COW, fsb, len);
1652}
1653
1654struct xfs_refcount_recovery {
1655 struct list_head rr_list;
1656 struct xfs_refcount_irec rr_rrec;
1657};
1658
1659/* Stuff an extent on the recovery list. */
1660STATIC int
1661xfs_refcount_recover_extent(
1662 struct xfs_btree_cur *cur,
1663 union xfs_btree_rec *rec,
1664 void *priv)
1665{
1666 struct list_head *debris = priv;
1667 struct xfs_refcount_recovery *rr;
1668
1669 if (XFS_IS_CORRUPT(cur->bc_mp,
1670 be32_to_cpu(rec->refc.rc_refcount) != 1))
1671 return -EFSCORRUPTED;
1672
1673 rr = kmem_alloc(sizeof(struct xfs_refcount_recovery), 0);
1674 xfs_refcount_btrec_to_irec(rec, &rr->rr_rrec);
1675 list_add_tail(&rr->rr_list, debris);
1676
1677 return 0;
1678}
1679
1680/* Find and remove leftover CoW reservations. */
1681int
1682xfs_refcount_recover_cow_leftovers(
1683 struct xfs_mount *mp,
1684 xfs_agnumber_t agno)
1685{
1686 struct xfs_trans *tp;
1687 struct xfs_btree_cur *cur;
1688 struct xfs_buf *agbp;
1689 struct xfs_refcount_recovery *rr, *n;
1690 struct list_head debris;
1691 union xfs_btree_irec low;
1692 union xfs_btree_irec high;
1693 xfs_fsblock_t fsb;
1694 xfs_agblock_t agbno;
1695 int error;
1696
1697 if (mp->m_sb.sb_agblocks >= XFS_REFC_COW_START)
1698 return -EOPNOTSUPP;
1699
1700 INIT_LIST_HEAD(&debris);
1701
1702 /*
1703 * In this first part, we use an empty transaction to gather up
1704 * all the leftover CoW extents so that we can subsequently
1705 * delete them. The empty transaction is used to avoid
1706 * a buffer lock deadlock if there happens to be a loop in the
1707 * refcountbt because we're allowed to re-grab a buffer that is
1708 * already attached to our transaction. When we're done
1709 * recording the CoW debris we cancel the (empty) transaction
1710 * and everything goes away cleanly.
1711 */
1712 error = xfs_trans_alloc_empty(mp, &tp);
1713 if (error)
1714 return error;
1715
1716 error = xfs_alloc_read_agf(mp, tp, agno, 0, &agbp);
1717 if (error)
1718 goto out_trans;
1719 cur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno);
1720
1721 /* Find all the leftover CoW staging extents. */
1722 memset(&low, 0, sizeof(low));
1723 memset(&high, 0, sizeof(high));
1724 low.rc.rc_startblock = XFS_REFC_COW_START;
1725 high.rc.rc_startblock = -1U;
1726 error = xfs_btree_query_range(cur, &low, &high,
1727 xfs_refcount_recover_extent, &debris);
1728 xfs_btree_del_cursor(cur, error);
1729 xfs_trans_brelse(tp, agbp);
1730 xfs_trans_cancel(tp);
1731 if (error)
1732 goto out_free;
1733
1734 /* Now iterate the list to free the leftovers */
1735 list_for_each_entry_safe(rr, n, &debris, rr_list) {
1736 /* Set up transaction. */
1737 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0, 0, &tp);
1738 if (error)
1739 goto out_free;
1740
1741 trace_xfs_refcount_recover_extent(mp, agno, &rr->rr_rrec);
1742
1743 /* Free the orphan record */
1744 agbno = rr->rr_rrec.rc_startblock - XFS_REFC_COW_START;
1745 fsb = XFS_AGB_TO_FSB(mp, agno, agbno);
1746 xfs_refcount_free_cow_extent(tp, fsb,
1747 rr->rr_rrec.rc_blockcount);
1748
1749 /* Free the block. */
1750 xfs_bmap_add_free(tp, fsb, rr->rr_rrec.rc_blockcount, NULL);
1751
1752 error = xfs_trans_commit(tp);
1753 if (error)
1754 goto out_free;
1755
1756 list_del(&rr->rr_list);
1757 kmem_free(rr);
1758 }
1759
1760 return error;
1761out_trans:
1762 xfs_trans_cancel(tp);
1763out_free:
1764 /* Free the leftover list */
1765 list_for_each_entry_safe(rr, n, &debris, rr_list) {
1766 list_del(&rr->rr_list);
1767 kmem_free(rr);
1768 }
1769 return error;
1770}
1771
1772/* Is there a record covering a given extent? */
1773int
1774xfs_refcount_has_record(
1775 struct xfs_btree_cur *cur,
1776 xfs_agblock_t bno,
1777 xfs_extlen_t len,
1778 bool *exists)
1779{
1780 union xfs_btree_irec low;
1781 union xfs_btree_irec high;
1782
1783 memset(&low, 0, sizeof(low));
1784 low.rc.rc_startblock = bno;
1785 memset(&high, 0xFF, sizeof(high));
1786 high.rc.rc_startblock = bno + len - 1;
1787
1788 return xfs_btree_has_record(cur, &low, &high, exists);
1789}