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perf tools: Don't clone maps from parent when synthesizing forks
[linux/fpc-iii.git] / fs / xfs / libxfs / xfs_refcount.c
blob542aa1475b5f969b3faf98f92fa2121461b5d629
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_sb.h"
13 #include "xfs_mount.h"
14 #include "xfs_defer.h"
15 #include "xfs_btree.h"
16 #include "xfs_bmap.h"
17 #include "xfs_refcount_btree.h"
18 #include "xfs_alloc.h"
19 #include "xfs_errortag.h"
20 #include "xfs_error.h"
21 #include "xfs_trace.h"
22 #include "xfs_cksum.h"
23 #include "xfs_trans.h"
24 #include "xfs_bit.h"
25 #include "xfs_refcount.h"
26 #include "xfs_rmap.h"
27
28 /* Allowable refcount adjustment amounts. */
29 enum xfs_refc_adjust_op {
30 XFS_REFCOUNT_ADJUST_INCREASE = 1,
31 XFS_REFCOUNT_ADJUST_DECREASE = -1,
32 XFS_REFCOUNT_ADJUST_COW_ALLOC = 0,
33 XFS_REFCOUNT_ADJUST_COW_FREE = -1,
34 };
35
36 STATIC int __xfs_refcount_cow_alloc(struct xfs_btree_cur *rcur,
37 xfs_agblock_t agbno, xfs_extlen_t aglen);
38 STATIC int __xfs_refcount_cow_free(struct xfs_btree_cur *rcur,
39 xfs_agblock_t agbno, xfs_extlen_t aglen);
40
41 /*
42 * Look up the first record less than or equal to [bno, len] in the btree
43 * given by cur.
44 */
45 int
46 xfs_refcount_lookup_le(
47 struct xfs_btree_cur *cur,
48 xfs_agblock_t bno,
49 int *stat)
50 {
51 trace_xfs_refcount_lookup(cur->bc_mp, cur->bc_private.a.agno, bno,
52 XFS_LOOKUP_LE);
53 cur->bc_rec.rc.rc_startblock = bno;
54 cur->bc_rec.rc.rc_blockcount = 0;
55 return xfs_btree_lookup(cur, XFS_LOOKUP_LE, stat);
56 }
57
58 /*
59 * Look up the first record greater than or equal to [bno, len] in the btree
60 * given by cur.
61 */
62 int
63 xfs_refcount_lookup_ge(
64 struct xfs_btree_cur *cur,
65 xfs_agblock_t bno,
66 int *stat)
67 {
68 trace_xfs_refcount_lookup(cur->bc_mp, cur->bc_private.a.agno, bno,
69 XFS_LOOKUP_GE);
70 cur->bc_rec.rc.rc_startblock = bno;
71 cur->bc_rec.rc.rc_blockcount = 0;
72 return xfs_btree_lookup(cur, XFS_LOOKUP_GE, stat);
73 }
74
75 /*
76 * Look up the first record equal to [bno, len] in the btree
77 * given by cur.
78 */
79 int
80 xfs_refcount_lookup_eq(
81 struct xfs_btree_cur *cur,
82 xfs_agblock_t bno,
83 int *stat)
84 {
85 trace_xfs_refcount_lookup(cur->bc_mp, cur->bc_private.a.agno, bno,
86 XFS_LOOKUP_LE);
87 cur->bc_rec.rc.rc_startblock = bno;
88 cur->bc_rec.rc.rc_blockcount = 0;
89 return xfs_btree_lookup(cur, XFS_LOOKUP_EQ, stat);
90 }
91
92 /* Convert on-disk record to in-core format. */
93 void
94 xfs_refcount_btrec_to_irec(
95 union xfs_btree_rec *rec,
96 struct xfs_refcount_irec *irec)
97 {
98 irec->rc_startblock = be32_to_cpu(rec->refc.rc_startblock);
99 irec->rc_blockcount = be32_to_cpu(rec->refc.rc_blockcount);
100 irec->rc_refcount = be32_to_cpu(rec->refc.rc_refcount);
101 }
102
103 /*
104 * Get the data from the pointed-to record.
105 */
106 int
107 xfs_refcount_get_rec(
108 struct xfs_btree_cur *cur,
109 struct xfs_refcount_irec *irec,
110 int *stat)
111 {
112 struct xfs_mount *mp = cur->bc_mp;
113 xfs_agnumber_t agno = cur->bc_private.a.agno;
114 union xfs_btree_rec *rec;
115 int error;
116 xfs_agblock_t realstart;
117
118 error = xfs_btree_get_rec(cur, &rec, stat);
119 if (error || !*stat)
120 return error;
121
122 xfs_refcount_btrec_to_irec(rec, irec);
123
124 agno = cur->bc_private.a.agno;
125 if (irec->rc_blockcount == 0 || irec->rc_blockcount > MAXREFCEXTLEN)
126 goto out_bad_rec;
127
128 /* handle special COW-staging state */
129 realstart = irec->rc_startblock;
130 if (realstart & XFS_REFC_COW_START) {
131 if (irec->rc_refcount != 1)
132 goto out_bad_rec;
133 realstart &= ~XFS_REFC_COW_START;
134 } else if (irec->rc_refcount < 2) {
135 goto out_bad_rec;
136 }
137
138 /* check for valid extent range, including overflow */
139 if (!xfs_verify_agbno(mp, agno, realstart))
140 goto out_bad_rec;
141 if (realstart > realstart + irec->rc_blockcount)
142 goto out_bad_rec;
143 if (!xfs_verify_agbno(mp, agno, realstart + irec->rc_blockcount - 1))
144 goto out_bad_rec;
145
146 if (irec->rc_refcount == 0 || irec->rc_refcount > MAXREFCOUNT)
147 goto out_bad_rec;
148
149 trace_xfs_refcount_get(cur->bc_mp, cur->bc_private.a.agno, irec);
150 return 0;
151
152 out_bad_rec:
153 xfs_warn(mp,
154 "Refcount BTree record corruption in AG %d detected!", agno);
155 xfs_warn(mp,
156 "Start block 0x%x, block count 0x%x, references 0x%x",
157 irec->rc_startblock, irec->rc_blockcount, irec->rc_refcount);
158 return -EFSCORRUPTED;
159 }
160
161 /*
162 * Update the record referred to by cur to the value given
163 * by [bno, len, refcount].
164 * This either works (return 0) or gets an EFSCORRUPTED error.
165 */
166 STATIC int
167 xfs_refcount_update(
168 struct xfs_btree_cur *cur,
169 struct xfs_refcount_irec *irec)
170 {
171 union xfs_btree_rec rec;
172 int error;
173
174 trace_xfs_refcount_update(cur->bc_mp, cur->bc_private.a.agno, irec);
175 rec.refc.rc_startblock = cpu_to_be32(irec->rc_startblock);
176 rec.refc.rc_blockcount = cpu_to_be32(irec->rc_blockcount);
177 rec.refc.rc_refcount = cpu_to_be32(irec->rc_refcount);
178 error = xfs_btree_update(cur, &rec);
179 if (error)
180 trace_xfs_refcount_update_error(cur->bc_mp,
181 cur->bc_private.a.agno, error, _RET_IP_);
182 return error;
183 }
184
185 /*
186 * Insert the record referred to by cur to the value given
187 * by [bno, len, refcount].
188 * This either works (return 0) or gets an EFSCORRUPTED error.
189 */
190 int
191 xfs_refcount_insert(
192 struct xfs_btree_cur *cur,
193 struct xfs_refcount_irec *irec,
194 int *i)
195 {
196 int error;
197
198 trace_xfs_refcount_insert(cur->bc_mp, cur->bc_private.a.agno, irec);
199 cur->bc_rec.rc.rc_startblock = irec->rc_startblock;
200 cur->bc_rec.rc.rc_blockcount = irec->rc_blockcount;
201 cur->bc_rec.rc.rc_refcount = irec->rc_refcount;
202 error = xfs_btree_insert(cur, i);
203 if (error)
204 goto out_error;
205 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, *i == 1, out_error);
206
207 out_error:
208 if (error)
209 trace_xfs_refcount_insert_error(cur->bc_mp,
210 cur->bc_private.a.agno, error, _RET_IP_);
211 return error;
212 }
213
214 /*
215 * Remove the record referred to by cur, then set the pointer to the spot
216 * where the record could be re-inserted, in case we want to increment or
217 * decrement the cursor.
218 * This either works (return 0) or gets an EFSCORRUPTED error.
219 */
220 STATIC int
221 xfs_refcount_delete(
222 struct xfs_btree_cur *cur,
223 int *i)
224 {
225 struct xfs_refcount_irec irec;
226 int found_rec;
227 int error;
228
229 error = xfs_refcount_get_rec(cur, &irec, &found_rec);
230 if (error)
231 goto out_error;
232 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
233 trace_xfs_refcount_delete(cur->bc_mp, cur->bc_private.a.agno, &irec);
234 error = xfs_btree_delete(cur, i);
235 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, *i == 1, out_error);
236 if (error)
237 goto out_error;
238 error = xfs_refcount_lookup_ge(cur, irec.rc_startblock, &found_rec);
239 out_error:
240 if (error)
241 trace_xfs_refcount_delete_error(cur->bc_mp,
242 cur->bc_private.a.agno, error, _RET_IP_);
243 return error;
244 }
245
246 /*
247 * Adjusting the Reference Count
248 *
249 * As stated elsewhere, the reference count btree (refcbt) stores
250 * >1 reference counts for extents of physical blocks. In this
251 * operation, we're either raising or lowering the reference count of
252 * some subrange stored in the tree:
253 *
254 * <------ adjustment range ------>
255 * ----+ +---+-----+ +--+--------+---------
256 * 2 | | 3 | 4 | |17| 55 | 10
257 * ----+ +---+-----+ +--+--------+---------
258 * X axis is physical blocks number;
259 * reference counts are the numbers inside the rectangles
260 *
261 * The first thing we need to do is to ensure that there are no
262 * refcount extents crossing either boundary of the range to be
263 * adjusted. For any extent that does cross a boundary, split it into
264 * two extents so that we can increment the refcount of one of the
265 * pieces later:
266 *
267 * <------ adjustment range ------>
268 * ----+ +---+-----+ +--+--------+----+----
269 * 2 | | 3 | 2 | |17| 55 | 10 | 10
270 * ----+ +---+-----+ +--+--------+----+----
271 *
272 * For this next step, let's assume that all the physical blocks in
273 * the adjustment range are mapped to a file and are therefore in use
274 * at least once. Therefore, we can infer that any gap in the
275 * refcount tree within the adjustment range represents a physical
276 * extent with refcount == 1:
277 *
278 * <------ adjustment range ------>
279 * ----+---+---+-----+-+--+--------+----+----
280 * 2 |"1"| 3 | 2 |1|17| 55 | 10 | 10
281 * ----+---+---+-----+-+--+--------+----+----
282 * ^
283 *
284 * For each extent that falls within the interval range, figure out
285 * which extent is to the left or the right of that extent. Now we
286 * have a left, current, and right extent. If the new reference count
287 * of the center extent enables us to merge left, center, and right
288 * into one record covering all three, do so. If the center extent is
289 * at the left end of the range, abuts the left extent, and its new
290 * reference count matches the left extent's record, then merge them.
291 * If the center extent is at the right end of the range, abuts the
292 * right extent, and the reference counts match, merge those. In the
293 * example, we can left merge (assuming an increment operation):
294 *
295 * <------ adjustment range ------>
296 * --------+---+-----+-+--+--------+----+----
297 * 2 | 3 | 2 |1|17| 55 | 10 | 10
298 * --------+---+-----+-+--+--------+----+----
299 * ^
300 *
301 * For all other extents within the range, adjust the reference count
302 * or delete it if the refcount falls below 2. If we were
303 * incrementing, the end result looks like this:
304 *
305 * <------ adjustment range ------>
306 * --------+---+-----+-+--+--------+----+----
307 * 2 | 4 | 3 |2|18| 56 | 11 | 10
308 * --------+---+-----+-+--+--------+----+----
309 *
310 * The result of a decrement operation looks as such:
311 *
312 * <------ adjustment range ------>
313 * ----+ +---+ +--+--------+----+----
314 * 2 | | 2 | |16| 54 | 9 | 10
315 * ----+ +---+ +--+--------+----+----
316 * DDDD 111111DD
317 *
318 * The blocks marked "D" are freed; the blocks marked "1" are only
319 * referenced once and therefore the record is removed from the
320 * refcount btree.
321 */
322
323 /* Next block after this extent. */
324 static inline xfs_agblock_t
325 xfs_refc_next(
326 struct xfs_refcount_irec *rc)
327 {
328 return rc->rc_startblock + rc->rc_blockcount;
329 }
330
331 /*
332 * Split a refcount extent that crosses agbno.
333 */
334 STATIC int
335 xfs_refcount_split_extent(
336 struct xfs_btree_cur *cur,
337 xfs_agblock_t agbno,
338 bool *shape_changed)
339 {
340 struct xfs_refcount_irec rcext, tmp;
341 int found_rec;
342 int error;
343
344 *shape_changed = false;
345 error = xfs_refcount_lookup_le(cur, agbno, &found_rec);
346 if (error)
347 goto out_error;
348 if (!found_rec)
349 return 0;
350
351 error = xfs_refcount_get_rec(cur, &rcext, &found_rec);
352 if (error)
353 goto out_error;
354 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
355 if (rcext.rc_startblock == agbno || xfs_refc_next(&rcext) <= agbno)
356 return 0;
357
358 *shape_changed = true;
359 trace_xfs_refcount_split_extent(cur->bc_mp, cur->bc_private.a.agno,
360 &rcext, agbno);
361
362 /* Establish the right extent. */
363 tmp = rcext;
364 tmp.rc_startblock = agbno;
365 tmp.rc_blockcount -= (agbno - rcext.rc_startblock);
366 error = xfs_refcount_update(cur, &tmp);
367 if (error)
368 goto out_error;
369
370 /* Insert the left extent. */
371 tmp = rcext;
372 tmp.rc_blockcount = agbno - rcext.rc_startblock;
373 error = xfs_refcount_insert(cur, &tmp, &found_rec);
374 if (error)
375 goto out_error;
376 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
377 return error;
378
379 out_error:
380 trace_xfs_refcount_split_extent_error(cur->bc_mp,
381 cur->bc_private.a.agno, error, _RET_IP_);
382 return error;
383 }
384
385 /*
386 * Merge the left, center, and right extents.
387 */
388 STATIC int
389 xfs_refcount_merge_center_extents(
390 struct xfs_btree_cur *cur,
391 struct xfs_refcount_irec *left,
392 struct xfs_refcount_irec *center,
393 struct xfs_refcount_irec *right,
394 unsigned long long extlen,
395 xfs_extlen_t *aglen)
396 {
397 int error;
398 int found_rec;
399
400 trace_xfs_refcount_merge_center_extents(cur->bc_mp,
401 cur->bc_private.a.agno, left, center, right);
402
403 /*
404 * Make sure the center and right extents are not in the btree.
405 * If the center extent was synthesized, the first delete call
406 * removes the right extent and we skip the second deletion.
407 * If center and right were in the btree, then the first delete
408 * call removes the center and the second one removes the right
409 * extent.
410 */
411 error = xfs_refcount_lookup_ge(cur, center->rc_startblock,
412 &found_rec);
413 if (error)
414 goto out_error;
415 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
416
417 error = xfs_refcount_delete(cur, &found_rec);
418 if (error)
419 goto out_error;
420 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
421
422 if (center->rc_refcount > 1) {
423 error = xfs_refcount_delete(cur, &found_rec);
424 if (error)
425 goto out_error;
426 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
427 out_error);
428 }
429
430 /* Enlarge the left extent. */
431 error = xfs_refcount_lookup_le(cur, left->rc_startblock,
432 &found_rec);
433 if (error)
434 goto out_error;
435 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
436
437 left->rc_blockcount = extlen;
438 error = xfs_refcount_update(cur, left);
439 if (error)
440 goto out_error;
441
442 *aglen = 0;
443 return error;
444
445 out_error:
446 trace_xfs_refcount_merge_center_extents_error(cur->bc_mp,
447 cur->bc_private.a.agno, error, _RET_IP_);
448 return error;
449 }
450
451 /*
452 * Merge with the left extent.
453 */
454 STATIC int
455 xfs_refcount_merge_left_extent(
456 struct xfs_btree_cur *cur,
457 struct xfs_refcount_irec *left,
458 struct xfs_refcount_irec *cleft,
459 xfs_agblock_t *agbno,
460 xfs_extlen_t *aglen)
461 {
462 int error;
463 int found_rec;
464
465 trace_xfs_refcount_merge_left_extent(cur->bc_mp,
466 cur->bc_private.a.agno, left, cleft);
467
468 /* If the extent at agbno (cleft) wasn't synthesized, remove it. */
469 if (cleft->rc_refcount > 1) {
470 error = xfs_refcount_lookup_le(cur, cleft->rc_startblock,
471 &found_rec);
472 if (error)
473 goto out_error;
474 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
475 out_error);
476
477 error = xfs_refcount_delete(cur, &found_rec);
478 if (error)
479 goto out_error;
480 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
481 out_error);
482 }
483
484 /* Enlarge the left extent. */
485 error = xfs_refcount_lookup_le(cur, left->rc_startblock,
486 &found_rec);
487 if (error)
488 goto out_error;
489 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
490
491 left->rc_blockcount += cleft->rc_blockcount;
492 error = xfs_refcount_update(cur, left);
493 if (error)
494 goto out_error;
495
496 *agbno += cleft->rc_blockcount;
497 *aglen -= cleft->rc_blockcount;
498 return error;
499
500 out_error:
501 trace_xfs_refcount_merge_left_extent_error(cur->bc_mp,
502 cur->bc_private.a.agno, error, _RET_IP_);
503 return error;
504 }
505
506 /*
507 * Merge with the right extent.
508 */
509 STATIC int
510 xfs_refcount_merge_right_extent(
511 struct xfs_btree_cur *cur,
512 struct xfs_refcount_irec *right,
513 struct xfs_refcount_irec *cright,
514 xfs_extlen_t *aglen)
515 {
516 int error;
517 int found_rec;
518
519 trace_xfs_refcount_merge_right_extent(cur->bc_mp,
520 cur->bc_private.a.agno, cright, right);
521
522 /*
523 * If the extent ending at agbno+aglen (cright) wasn't synthesized,
524 * remove it.
525 */
526 if (cright->rc_refcount > 1) {
527 error = xfs_refcount_lookup_le(cur, cright->rc_startblock,
528 &found_rec);
529 if (error)
530 goto out_error;
531 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
532 out_error);
533
534 error = xfs_refcount_delete(cur, &found_rec);
535 if (error)
536 goto out_error;
537 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
538 out_error);
539 }
540
541 /* Enlarge the right extent. */
542 error = xfs_refcount_lookup_le(cur, right->rc_startblock,
543 &found_rec);
544 if (error)
545 goto out_error;
546 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
547
548 right->rc_startblock -= cright->rc_blockcount;
549 right->rc_blockcount += cright->rc_blockcount;
550 error = xfs_refcount_update(cur, right);
551 if (error)
552 goto out_error;
553
554 *aglen -= cright->rc_blockcount;
555 return error;
556
557 out_error:
558 trace_xfs_refcount_merge_right_extent_error(cur->bc_mp,
559 cur->bc_private.a.agno, error, _RET_IP_);
560 return error;
561 }
562
563 #define XFS_FIND_RCEXT_SHARED 1
564 #define XFS_FIND_RCEXT_COW 2
565 /*
566 * Find the left extent and the one after it (cleft). This function assumes
567 * that we've already split any extent crossing agbno.
568 */
569 STATIC int
570 xfs_refcount_find_left_extents(
571 struct xfs_btree_cur *cur,
572 struct xfs_refcount_irec *left,
573 struct xfs_refcount_irec *cleft,
574 xfs_agblock_t agbno,
575 xfs_extlen_t aglen,
576 int flags)
577 {
578 struct xfs_refcount_irec tmp;
579 int error;
580 int found_rec;
581
582 left->rc_startblock = cleft->rc_startblock = NULLAGBLOCK;
583 error = xfs_refcount_lookup_le(cur, agbno - 1, &found_rec);
584 if (error)
585 goto out_error;
586 if (!found_rec)
587 return 0;
588
589 error = xfs_refcount_get_rec(cur, &tmp, &found_rec);
590 if (error)
591 goto out_error;
592 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
593
594 if (xfs_refc_next(&tmp) != agbno)
595 return 0;
596 if ((flags & XFS_FIND_RCEXT_SHARED) && tmp.rc_refcount < 2)
597 return 0;
598 if ((flags & XFS_FIND_RCEXT_COW) && tmp.rc_refcount > 1)
599 return 0;
600 /* We have a left extent; retrieve (or invent) the next right one */
601 *left = tmp;
602
603 error = xfs_btree_increment(cur, 0, &found_rec);
604 if (error)
605 goto out_error;
606 if (found_rec) {
607 error = xfs_refcount_get_rec(cur, &tmp, &found_rec);
608 if (error)
609 goto out_error;
610 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
611 out_error);
612
613 /* if tmp starts at the end of our range, just use that */
614 if (tmp.rc_startblock == agbno)
615 *cleft = tmp;
616 else {
617 /*
618 * There's a gap in the refcntbt at the start of the
619 * range we're interested in (refcount == 1) so
620 * synthesize the implied extent and pass it back.
621 * We assume here that the agbno/aglen range was
622 * passed in from a data fork extent mapping and
623 * therefore is allocated to exactly one owner.
624 */
625 cleft->rc_startblock = agbno;
626 cleft->rc_blockcount = min(aglen,
627 tmp.rc_startblock - agbno);
628 cleft->rc_refcount = 1;
629 }
630 } else {
631 /*
632 * No extents, so pretend that there's one covering the whole
633 * range.
634 */
635 cleft->rc_startblock = agbno;
636 cleft->rc_blockcount = aglen;
637 cleft->rc_refcount = 1;
638 }
639 trace_xfs_refcount_find_left_extent(cur->bc_mp, cur->bc_private.a.agno,
640 left, cleft, agbno);
641 return error;
642
643 out_error:
644 trace_xfs_refcount_find_left_extent_error(cur->bc_mp,
645 cur->bc_private.a.agno, error, _RET_IP_);
646 return error;
647 }
648
649 /*
650 * Find the right extent and the one before it (cright). This function
651 * assumes that we've already split any extents crossing agbno + aglen.
652 */
653 STATIC int
654 xfs_refcount_find_right_extents(
655 struct xfs_btree_cur *cur,
656 struct xfs_refcount_irec *right,
657 struct xfs_refcount_irec *cright,
658 xfs_agblock_t agbno,
659 xfs_extlen_t aglen,
660 int flags)
661 {
662 struct xfs_refcount_irec tmp;
663 int error;
664 int found_rec;
665
666 right->rc_startblock = cright->rc_startblock = NULLAGBLOCK;
667 error = xfs_refcount_lookup_ge(cur, agbno + aglen, &found_rec);
668 if (error)
669 goto out_error;
670 if (!found_rec)
671 return 0;
672
673 error = xfs_refcount_get_rec(cur, &tmp, &found_rec);
674 if (error)
675 goto out_error;
676 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
677
678 if (tmp.rc_startblock != agbno + aglen)
679 return 0;
680 if ((flags & XFS_FIND_RCEXT_SHARED) && tmp.rc_refcount < 2)
681 return 0;
682 if ((flags & XFS_FIND_RCEXT_COW) && tmp.rc_refcount > 1)
683 return 0;
684 /* We have a right extent; retrieve (or invent) the next left one */
685 *right = tmp;
686
687 error = xfs_btree_decrement(cur, 0, &found_rec);
688 if (error)
689 goto out_error;
690 if (found_rec) {
691 error = xfs_refcount_get_rec(cur, &tmp, &found_rec);
692 if (error)
693 goto out_error;
694 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
695 out_error);
696
697 /* if tmp ends at the end of our range, just use that */
698 if (xfs_refc_next(&tmp) == agbno + aglen)
699 *cright = tmp;
700 else {
701 /*
702 * There's a gap in the refcntbt at the end of the
703 * range we're interested in (refcount == 1) so
704 * create the implied extent and pass it back.
705 * We assume here that the agbno/aglen range was
706 * passed in from a data fork extent mapping and
707 * therefore is allocated to exactly one owner.
708 */
709 cright->rc_startblock = max(agbno, xfs_refc_next(&tmp));
710 cright->rc_blockcount = right->rc_startblock -
711 cright->rc_startblock;
712 cright->rc_refcount = 1;
713 }
714 } else {
715 /*
716 * No extents, so pretend that there's one covering the whole
717 * range.
718 */
719 cright->rc_startblock = agbno;
720 cright->rc_blockcount = aglen;
721 cright->rc_refcount = 1;
722 }
723 trace_xfs_refcount_find_right_extent(cur->bc_mp, cur->bc_private.a.agno,
724 cright, right, agbno + aglen);
725 return error;
726
727 out_error:
728 trace_xfs_refcount_find_right_extent_error(cur->bc_mp,
729 cur->bc_private.a.agno, error, _RET_IP_);
730 return error;
731 }
732
733 /* Is this extent valid? */
734 static inline bool
735 xfs_refc_valid(
736 struct xfs_refcount_irec *rc)
737 {
738 return rc->rc_startblock != NULLAGBLOCK;
739 }
740
741 /*
742 * Try to merge with any extents on the boundaries of the adjustment range.
743 */
744 STATIC int
745 xfs_refcount_merge_extents(
746 struct xfs_btree_cur *cur,
747 xfs_agblock_t *agbno,
748 xfs_extlen_t *aglen,
749 enum xfs_refc_adjust_op adjust,
750 int flags,
751 bool *shape_changed)
752 {
753 struct xfs_refcount_irec left = {0}, cleft = {0};
754 struct xfs_refcount_irec cright = {0}, right = {0};
755 int error;
756 unsigned long long ulen;
757 bool cequal;
758
759 *shape_changed = false;
760 /*
761 * Find the extent just below agbno [left], just above agbno [cleft],
762 * just below (agbno + aglen) [cright], and just above (agbno + aglen)
763 * [right].
764 */
765 error = xfs_refcount_find_left_extents(cur, &left, &cleft, *agbno,
766 *aglen, flags);
767 if (error)
768 return error;
769 error = xfs_refcount_find_right_extents(cur, &right, &cright, *agbno,
770 *aglen, flags);
771 if (error)
772 return error;
773
774 /* No left or right extent to merge; exit. */
775 if (!xfs_refc_valid(&left) && !xfs_refc_valid(&right))
776 return 0;
777
778 cequal = (cleft.rc_startblock == cright.rc_startblock) &&
779 (cleft.rc_blockcount == cright.rc_blockcount);
780
781 /* Try to merge left, cleft, and right. cleft must == cright. */
782 ulen = (unsigned long long)left.rc_blockcount + cleft.rc_blockcount +
783 right.rc_blockcount;
784 if (xfs_refc_valid(&left) && xfs_refc_valid(&right) &&
785 xfs_refc_valid(&cleft) && xfs_refc_valid(&cright) && cequal &&
786 left.rc_refcount == cleft.rc_refcount + adjust &&
787 right.rc_refcount == cleft.rc_refcount + adjust &&
788 ulen < MAXREFCEXTLEN) {
789 *shape_changed = true;
790 return xfs_refcount_merge_center_extents(cur, &left, &cleft,
791 &right, ulen, aglen);
792 }
793
794 /* Try to merge left and cleft. */
795 ulen = (unsigned long long)left.rc_blockcount + cleft.rc_blockcount;
796 if (xfs_refc_valid(&left) && xfs_refc_valid(&cleft) &&
797 left.rc_refcount == cleft.rc_refcount + adjust &&
798 ulen < MAXREFCEXTLEN) {
799 *shape_changed = true;
800 error = xfs_refcount_merge_left_extent(cur, &left, &cleft,
801 agbno, aglen);
802 if (error)
803 return error;
804
805 /*
806 * If we just merged left + cleft and cleft == cright,
807 * we no longer have a cright to merge with right. We're done.
808 */
809 if (cequal)
810 return 0;
811 }
812
813 /* Try to merge cright and right. */
814 ulen = (unsigned long long)right.rc_blockcount + cright.rc_blockcount;
815 if (xfs_refc_valid(&right) && xfs_refc_valid(&cright) &&
816 right.rc_refcount == cright.rc_refcount + adjust &&
817 ulen < MAXREFCEXTLEN) {
818 *shape_changed = true;
819 return xfs_refcount_merge_right_extent(cur, &right, &cright,
820 aglen);
821 }
822
823 return error;
824 }
825
826 /*
827 * XXX: This is a pretty hand-wavy estimate. The penalty for guessing
828 * true incorrectly is a shutdown FS; the penalty for guessing false
829 * incorrectly is more transaction rolls than might be necessary.
830 * Be conservative here.
831 */
832 static bool
833 xfs_refcount_still_have_space(
834 struct xfs_btree_cur *cur)
835 {
836 unsigned long overhead;
837
838 overhead = cur->bc_private.a.priv.refc.shape_changes *
839 xfs_allocfree_log_count(cur->bc_mp, 1);
840 overhead *= cur->bc_mp->m_sb.sb_blocksize;
841
842 /*
843 * Only allow 2 refcount extent updates per transaction if the
844 * refcount continue update "error" has been injected.
845 */
846 if (cur->bc_private.a.priv.refc.nr_ops > 2 &&
847 XFS_TEST_ERROR(false, cur->bc_mp,
848 XFS_ERRTAG_REFCOUNT_CONTINUE_UPDATE))
849 return false;
850
851 if (cur->bc_private.a.priv.refc.nr_ops == 0)
852 return true;
853 else if (overhead > cur->bc_tp->t_log_res)
854 return false;
855 return cur->bc_tp->t_log_res - overhead >
856 cur->bc_private.a.priv.refc.nr_ops * XFS_REFCOUNT_ITEM_OVERHEAD;
857 }
858
859 /*
860 * Adjust the refcounts of middle extents. At this point we should have
861 * split extents that crossed the adjustment range; merged with adjacent
862 * extents; and updated agbno/aglen to reflect the merges. Therefore,
863 * all we have to do is update the extents inside [agbno, agbno + aglen].
864 */
865 STATIC int
866 xfs_refcount_adjust_extents(
867 struct xfs_btree_cur *cur,
868 xfs_agblock_t *agbno,
869 xfs_extlen_t *aglen,
870 enum xfs_refc_adjust_op adj,
871 struct xfs_owner_info *oinfo)
872 {
873 struct xfs_refcount_irec ext, tmp;
874 int error;
875 int found_rec, found_tmp;
876 xfs_fsblock_t fsbno;
877
878 /* Merging did all the work already. */
879 if (*aglen == 0)
880 return 0;
881
882 error = xfs_refcount_lookup_ge(cur, *agbno, &found_rec);
883 if (error)
884 goto out_error;
885
886 while (*aglen > 0 && xfs_refcount_still_have_space(cur)) {
887 error = xfs_refcount_get_rec(cur, &ext, &found_rec);
888 if (error)
889 goto out_error;
890 if (!found_rec) {
891 ext.rc_startblock = cur->bc_mp->m_sb.sb_agblocks;
892 ext.rc_blockcount = 0;
893 ext.rc_refcount = 0;
894 }
895
896 /*
897 * Deal with a hole in the refcount tree; if a file maps to
898 * these blocks and there's no refcountbt record, pretend that
899 * there is one with refcount == 1.
900 */
901 if (ext.rc_startblock != *agbno) {
902 tmp.rc_startblock = *agbno;
903 tmp.rc_blockcount = min(*aglen,
904 ext.rc_startblock - *agbno);
905 tmp.rc_refcount = 1 + adj;
906 trace_xfs_refcount_modify_extent(cur->bc_mp,
907 cur->bc_private.a.agno, &tmp);
908
909 /*
910 * Either cover the hole (increment) or
911 * delete the range (decrement).
912 */
913 if (tmp.rc_refcount) {
914 error = xfs_refcount_insert(cur, &tmp,
915 &found_tmp);
916 if (error)
917 goto out_error;
918 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
919 found_tmp == 1, out_error);
920 cur->bc_private.a.priv.refc.nr_ops++;
921 } else {
922 fsbno = XFS_AGB_TO_FSB(cur->bc_mp,
923 cur->bc_private.a.agno,
924 tmp.rc_startblock);
925 xfs_bmap_add_free(cur->bc_tp, fsbno,
926 tmp.rc_blockcount, oinfo);
927 }
928
929 (*agbno) += tmp.rc_blockcount;
930 (*aglen) -= tmp.rc_blockcount;
931
932 error = xfs_refcount_lookup_ge(cur, *agbno,
933 &found_rec);
934 if (error)
935 goto out_error;
936 }
937
938 /* Stop if there's nothing left to modify */
939 if (*aglen == 0 || !xfs_refcount_still_have_space(cur))
940 break;
941
942 /*
943 * Adjust the reference count and either update the tree
944 * (incr) or free the blocks (decr).
945 */
946 if (ext.rc_refcount == MAXREFCOUNT)
947 goto skip;
948 ext.rc_refcount += adj;
949 trace_xfs_refcount_modify_extent(cur->bc_mp,
950 cur->bc_private.a.agno, &ext);
951 if (ext.rc_refcount > 1) {
952 error = xfs_refcount_update(cur, &ext);
953 if (error)
954 goto out_error;
955 cur->bc_private.a.priv.refc.nr_ops++;
956 } else if (ext.rc_refcount == 1) {
957 error = xfs_refcount_delete(cur, &found_rec);
958 if (error)
959 goto out_error;
960 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
961 found_rec == 1, out_error);
962 cur->bc_private.a.priv.refc.nr_ops++;
963 goto advloop;
964 } else {
965 fsbno = XFS_AGB_TO_FSB(cur->bc_mp,
966 cur->bc_private.a.agno,
967 ext.rc_startblock);
968 xfs_bmap_add_free(cur->bc_tp, fsbno, ext.rc_blockcount,
969 oinfo);
970 }
971
972 skip:
973 error = xfs_btree_increment(cur, 0, &found_rec);
974 if (error)
975 goto out_error;
976
977 advloop:
978 (*agbno) += ext.rc_blockcount;
979 (*aglen) -= ext.rc_blockcount;
980 }
981
982 return error;
983 out_error:
984 trace_xfs_refcount_modify_extent_error(cur->bc_mp,
985 cur->bc_private.a.agno, error, _RET_IP_);
986 return error;
987 }
988
989 /* Adjust the reference count of a range of AG blocks. */
990 STATIC int
991 xfs_refcount_adjust(
992 struct xfs_btree_cur *cur,
993 xfs_agblock_t agbno,
994 xfs_extlen_t aglen,
995 xfs_agblock_t *new_agbno,
996 xfs_extlen_t *new_aglen,
997 enum xfs_refc_adjust_op adj,
998 struct xfs_owner_info *oinfo)
999 {
1000 bool shape_changed;
1001 int shape_changes = 0;
1002 int error;
1003
1004 *new_agbno = agbno;
1005 *new_aglen = aglen;
1006 if (adj == XFS_REFCOUNT_ADJUST_INCREASE)
1007 trace_xfs_refcount_increase(cur->bc_mp, cur->bc_private.a.agno,
1008 agbno, aglen);
1009 else
1010 trace_xfs_refcount_decrease(cur->bc_mp, cur->bc_private.a.agno,
1011 agbno, aglen);
1012
1013 /*
1014 * Ensure that no rcextents cross the boundary of the adjustment range.
1015 */
1016 error = xfs_refcount_split_extent(cur, agbno, &shape_changed);
1017 if (error)
1018 goto out_error;
1019 if (shape_changed)
1020 shape_changes++;
1021
1022 error = xfs_refcount_split_extent(cur, agbno + aglen, &shape_changed);
1023 if (error)
1024 goto out_error;
1025 if (shape_changed)
1026 shape_changes++;
1027
1028 /*
1029 * Try to merge with the left or right extents of the range.
1030 */
1031 error = xfs_refcount_merge_extents(cur, new_agbno, new_aglen, adj,
1032 XFS_FIND_RCEXT_SHARED, &shape_changed);
1033 if (error)
1034 goto out_error;
1035 if (shape_changed)
1036 shape_changes++;
1037 if (shape_changes)
1038 cur->bc_private.a.priv.refc.shape_changes++;
1039
1040 /* Now that we've taken care of the ends, adjust the middle extents */
1041 error = xfs_refcount_adjust_extents(cur, new_agbno, new_aglen,
1042 adj, oinfo);
1043 if (error)
1044 goto out_error;
1045
1046 return 0;
1047
1048 out_error:
1049 trace_xfs_refcount_adjust_error(cur->bc_mp, cur->bc_private.a.agno,
1050 error, _RET_IP_);
1051 return error;
1052 }
1053
1054 /* Clean up after calling xfs_refcount_finish_one. */
1055 void
1056 xfs_refcount_finish_one_cleanup(
1057 struct xfs_trans *tp,
1058 struct xfs_btree_cur *rcur,
1059 int error)
1060 {
1061 struct xfs_buf *agbp;
1062
1063 if (rcur == NULL)
1064 return;
1065 agbp = rcur->bc_private.a.agbp;
1066 xfs_btree_del_cursor(rcur, error);
1067 if (error)
1068 xfs_trans_brelse(tp, agbp);
1069 }
1070
1071 /*
1072 * Process one of the deferred refcount operations. We pass back the
1073 * btree cursor to maintain our lock on the btree between calls.
1074 * This saves time and eliminates a buffer deadlock between the
1075 * superblock and the AGF because we'll always grab them in the same
1076 * order.
1077 */
1078 int
1079 xfs_refcount_finish_one(
1080 struct xfs_trans *tp,
1081 enum xfs_refcount_intent_type type,
1082 xfs_fsblock_t startblock,
1083 xfs_extlen_t blockcount,
1084 xfs_fsblock_t *new_fsb,
1085 xfs_extlen_t *new_len,
1086 struct xfs_btree_cur **pcur)
1087 {
1088 struct xfs_mount *mp = tp->t_mountp;
1089 struct xfs_btree_cur *rcur;
1090 struct xfs_buf *agbp = NULL;
1091 int error = 0;
1092 xfs_agnumber_t agno;
1093 xfs_agblock_t bno;
1094 xfs_agblock_t new_agbno;
1095 unsigned long nr_ops = 0;
1096 int shape_changes = 0;
1097
1098 agno = XFS_FSB_TO_AGNO(mp, startblock);
1099 ASSERT(agno != NULLAGNUMBER);
1100 bno = XFS_FSB_TO_AGBNO(mp, startblock);
1101
1102 trace_xfs_refcount_deferred(mp, XFS_FSB_TO_AGNO(mp, startblock),
1103 type, XFS_FSB_TO_AGBNO(mp, startblock),
1104 blockcount);
1105
1106 if (XFS_TEST_ERROR(false, mp,
1107 XFS_ERRTAG_REFCOUNT_FINISH_ONE))
1108 return -EIO;
1109
1110 /*
1111 * If we haven't gotten a cursor or the cursor AG doesn't match
1112 * the startblock, get one now.
1113 */
1114 rcur = *pcur;
1115 if (rcur != NULL && rcur->bc_private.a.agno != agno) {
1116 nr_ops = rcur->bc_private.a.priv.refc.nr_ops;
1117 shape_changes = rcur->bc_private.a.priv.refc.shape_changes;
1118 xfs_refcount_finish_one_cleanup(tp, rcur, 0);
1119 rcur = NULL;
1120 *pcur = NULL;
1121 }
1122 if (rcur == NULL) {
1123 error = xfs_alloc_read_agf(tp->t_mountp, tp, agno,
1124 XFS_ALLOC_FLAG_FREEING, &agbp);
1125 if (error)
1126 return error;
1127 if (!agbp)
1128 return -EFSCORRUPTED;
1129
1130 rcur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno);
1131 if (!rcur) {
1132 error = -ENOMEM;
1133 goto out_cur;
1134 }
1135 rcur->bc_private.a.priv.refc.nr_ops = nr_ops;
1136 rcur->bc_private.a.priv.refc.shape_changes = shape_changes;
1137 }
1138 *pcur = rcur;
1139
1140 switch (type) {
1141 case XFS_REFCOUNT_INCREASE:
1142 error = xfs_refcount_adjust(rcur, bno, blockcount, &new_agbno,
1143 new_len, XFS_REFCOUNT_ADJUST_INCREASE, NULL);
1144 *new_fsb = XFS_AGB_TO_FSB(mp, agno, new_agbno);
1145 break;
1146 case XFS_REFCOUNT_DECREASE:
1147 error = xfs_refcount_adjust(rcur, bno, blockcount, &new_agbno,
1148 new_len, XFS_REFCOUNT_ADJUST_DECREASE, NULL);
1149 *new_fsb = XFS_AGB_TO_FSB(mp, agno, new_agbno);
1150 break;
1151 case XFS_REFCOUNT_ALLOC_COW:
1152 *new_fsb = startblock + blockcount;
1153 *new_len = 0;
1154 error = __xfs_refcount_cow_alloc(rcur, bno, blockcount);
1155 break;
1156 case XFS_REFCOUNT_FREE_COW:
1157 *new_fsb = startblock + blockcount;
1158 *new_len = 0;
1159 error = __xfs_refcount_cow_free(rcur, bno, blockcount);
1160 break;
1161 default:
1162 ASSERT(0);
1163 error = -EFSCORRUPTED;
1164 }
1165 if (!error && *new_len > 0)
1166 trace_xfs_refcount_finish_one_leftover(mp, agno, type,
1167 bno, blockcount, new_agbno, *new_len);
1168 return error;
1169
1170 out_cur:
1171 xfs_trans_brelse(tp, agbp);
1172
1173 return error;
1174 }
1175
1176 /*
1177 * Record a refcount intent for later processing.
1178 */
1179 static int
1180 __xfs_refcount_add(
1181 struct xfs_trans *tp,
1182 enum xfs_refcount_intent_type type,
1183 xfs_fsblock_t startblock,
1184 xfs_extlen_t blockcount)
1185 {
1186 struct xfs_refcount_intent *ri;
1187
1188 trace_xfs_refcount_defer(tp->t_mountp,
1189 XFS_FSB_TO_AGNO(tp->t_mountp, startblock),
1190 type, XFS_FSB_TO_AGBNO(tp->t_mountp, startblock),
1191 blockcount);
1192
1193 ri = kmem_alloc(sizeof(struct xfs_refcount_intent),
1194 KM_SLEEP | KM_NOFS);
1195 INIT_LIST_HEAD(&ri->ri_list);
1196 ri->ri_type = type;
1197 ri->ri_startblock = startblock;
1198 ri->ri_blockcount = blockcount;
1199
1200 xfs_defer_add(tp, XFS_DEFER_OPS_TYPE_REFCOUNT, &ri->ri_list);
1201 return 0;
1202 }
1203
1204 /*
1205 * Increase the reference count of the blocks backing a file's extent.
1206 */
1207 int
1208 xfs_refcount_increase_extent(
1209 struct xfs_trans *tp,
1210 struct xfs_bmbt_irec *PREV)
1211 {
1212 if (!xfs_sb_version_hasreflink(&tp->t_mountp->m_sb))
1213 return 0;
1214
1215 return __xfs_refcount_add(tp, XFS_REFCOUNT_INCREASE,
1216 PREV->br_startblock, PREV->br_blockcount);
1217 }
1218
1219 /*
1220 * Decrease the reference count of the blocks backing a file's extent.
1221 */
1222 int
1223 xfs_refcount_decrease_extent(
1224 struct xfs_trans *tp,
1225 struct xfs_bmbt_irec *PREV)
1226 {
1227 if (!xfs_sb_version_hasreflink(&tp->t_mountp->m_sb))
1228 return 0;
1229
1230 return __xfs_refcount_add(tp, XFS_REFCOUNT_DECREASE,
1231 PREV->br_startblock, PREV->br_blockcount);
1232 }
1233
1234 /*
1235 * Given an AG extent, find the lowest-numbered run of shared blocks
1236 * within that range and return the range in fbno/flen. If
1237 * find_end_of_shared is set, return the longest contiguous extent of
1238 * shared blocks; if not, just return the first extent we find. If no
1239 * shared blocks are found, fbno and flen will be set to NULLAGBLOCK
1240 * and 0, respectively.
1241 */
1242 int
1243 xfs_refcount_find_shared(
1244 struct xfs_btree_cur *cur,
1245 xfs_agblock_t agbno,
1246 xfs_extlen_t aglen,
1247 xfs_agblock_t *fbno,
1248 xfs_extlen_t *flen,
1249 bool find_end_of_shared)
1250 {
1251 struct xfs_refcount_irec tmp;
1252 int i;
1253 int have;
1254 int error;
1255
1256 trace_xfs_refcount_find_shared(cur->bc_mp, cur->bc_private.a.agno,
1257 agbno, aglen);
1258
1259 /* By default, skip the whole range */
1260 *fbno = NULLAGBLOCK;
1261 *flen = 0;
1262
1263 /* Try to find a refcount extent that crosses the start */
1264 error = xfs_refcount_lookup_le(cur, agbno, &have);
1265 if (error)
1266 goto out_error;
1267 if (!have) {
1268 /* No left extent, look at the next one */
1269 error = xfs_btree_increment(cur, 0, &have);
1270 if (error)
1271 goto out_error;
1272 if (!have)
1273 goto done;
1274 }
1275 error = xfs_refcount_get_rec(cur, &tmp, &i);
1276 if (error)
1277 goto out_error;
1278 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, i == 1, out_error);
1279
1280 /* If the extent ends before the start, look at the next one */
1281 if (tmp.rc_startblock + tmp.rc_blockcount <= agbno) {
1282 error = xfs_btree_increment(cur, 0, &have);
1283 if (error)
1284 goto out_error;
1285 if (!have)
1286 goto done;
1287 error = xfs_refcount_get_rec(cur, &tmp, &i);
1288 if (error)
1289 goto out_error;
1290 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, i == 1, out_error);
1291 }
1292
1293 /* If the extent starts after the range we want, bail out */
1294 if (tmp.rc_startblock >= agbno + aglen)
1295 goto done;
1296
1297 /* We found the start of a shared extent! */
1298 if (tmp.rc_startblock < agbno) {
1299 tmp.rc_blockcount -= (agbno - tmp.rc_startblock);
1300 tmp.rc_startblock = agbno;
1301 }
1302
1303 *fbno = tmp.rc_startblock;
1304 *flen = min(tmp.rc_blockcount, agbno + aglen - *fbno);
1305 if (!find_end_of_shared)
1306 goto done;
1307
1308 /* Otherwise, find the end of this shared extent */
1309 while (*fbno + *flen < agbno + aglen) {
1310 error = xfs_btree_increment(cur, 0, &have);
1311 if (error)
1312 goto out_error;
1313 if (!have)
1314 break;
1315 error = xfs_refcount_get_rec(cur, &tmp, &i);
1316 if (error)
1317 goto out_error;
1318 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, i == 1, out_error);
1319 if (tmp.rc_startblock >= agbno + aglen ||
1320 tmp.rc_startblock != *fbno + *flen)
1321 break;
1322 *flen = min(*flen + tmp.rc_blockcount, agbno + aglen - *fbno);
1323 }
1324
1325 done:
1326 trace_xfs_refcount_find_shared_result(cur->bc_mp,
1327 cur->bc_private.a.agno, *fbno, *flen);
1328
1329 out_error:
1330 if (error)
1331 trace_xfs_refcount_find_shared_error(cur->bc_mp,
1332 cur->bc_private.a.agno, error, _RET_IP_);
1333 return error;
1334 }
1335
1336 /*
1337 * Recovering CoW Blocks After a Crash
1338 *
1339 * Due to the way that the copy on write mechanism works, there's a window of
1340 * opportunity in which we can lose track of allocated blocks during a crash.
1341 * Because CoW uses delayed allocation in the in-core CoW fork, writeback
1342 * causes blocks to be allocated and stored in the CoW fork. The blocks are
1343 * no longer in the free space btree but are not otherwise recorded anywhere
1344 * until the write completes and the blocks are mapped into the file. A crash
1345 * in between allocation and remapping results in the replacement blocks being
1346 * lost. This situation is exacerbated by the CoW extent size hint because
1347 * allocations can hang around for long time.
1348 *
1349 * However, there is a place where we can record these allocations before they
1350 * become mappings -- the reference count btree. The btree does not record
1351 * extents with refcount == 1, so we can record allocations with a refcount of
1352 * 1. Blocks being used for CoW writeout cannot be shared, so there should be
1353 * no conflict with shared block records. These mappings should be created
1354 * when we allocate blocks to the CoW fork and deleted when they're removed
1355 * from the CoW fork.
1356 *
1357 * Minor nit: records for in-progress CoW allocations and records for shared
1358 * extents must never be merged, to preserve the property that (except for CoW
1359 * allocations) there are no refcount btree entries with refcount == 1. The
1360 * only time this could potentially happen is when unsharing a block that's
1361 * adjacent to CoW allocations, so we must be careful to avoid this.
1362 *
1363 * At mount time we recover lost CoW allocations by searching the refcount
1364 * btree for these refcount == 1 mappings. These represent CoW allocations
1365 * that were in progress at the time the filesystem went down, so we can free
1366 * them to get the space back.
1367 *
1368 * This mechanism is superior to creating EFIs for unmapped CoW extents for
1369 * several reasons -- first, EFIs pin the tail of the log and would have to be
1370 * periodically relogged to avoid filling up the log. Second, CoW completions
1371 * will have to file an EFD and create new EFIs for whatever remains in the
1372 * CoW fork; this partially takes care of (1) but extent-size reservations
1373 * will have to periodically relog even if there's no writeout in progress.
1374 * This can happen if the CoW extent size hint is set, which you really want.
1375 * Third, EFIs cannot currently be automatically relogged into newer
1376 * transactions to advance the log tail. Fourth, stuffing the log full of
1377 * EFIs places an upper bound on the number of CoW allocations that can be
1378 * held filesystem-wide at any given time. Recording them in the refcount
1379 * btree doesn't require us to maintain any state in memory and doesn't pin
1380 * the log.
1381 */
1382 /*
1383 * Adjust the refcounts of CoW allocations. These allocations are "magic"
1384 * in that they're not referenced anywhere else in the filesystem, so we
1385 * stash them in the refcount btree with a refcount of 1 until either file
1386 * remapping (or CoW cancellation) happens.
1387 */
1388 STATIC int
1389 xfs_refcount_adjust_cow_extents(
1390 struct xfs_btree_cur *cur,
1391 xfs_agblock_t agbno,
1392 xfs_extlen_t aglen,
1393 enum xfs_refc_adjust_op adj)
1394 {
1395 struct xfs_refcount_irec ext, tmp;
1396 int error;
1397 int found_rec, found_tmp;
1398
1399 if (aglen == 0)
1400 return 0;
1401
1402 /* Find any overlapping refcount records */
1403 error = xfs_refcount_lookup_ge(cur, agbno, &found_rec);
1404 if (error)
1405 goto out_error;
1406 error = xfs_refcount_get_rec(cur, &ext, &found_rec);
1407 if (error)
1408 goto out_error;
1409 if (!found_rec) {
1410 ext.rc_startblock = cur->bc_mp->m_sb.sb_agblocks +
1411 XFS_REFC_COW_START;
1412 ext.rc_blockcount = 0;
1413 ext.rc_refcount = 0;
1414 }
1415
1416 switch (adj) {
1417 case XFS_REFCOUNT_ADJUST_COW_ALLOC:
1418 /* Adding a CoW reservation, there should be nothing here. */
1419 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
1420 ext.rc_startblock >= agbno + aglen, out_error);
1421
1422 tmp.rc_startblock = agbno;
1423 tmp.rc_blockcount = aglen;
1424 tmp.rc_refcount = 1;
1425 trace_xfs_refcount_modify_extent(cur->bc_mp,
1426 cur->bc_private.a.agno, &tmp);
1427
1428 error = xfs_refcount_insert(cur, &tmp,
1429 &found_tmp);
1430 if (error)
1431 goto out_error;
1432 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
1433 found_tmp == 1, out_error);
1434 break;
1435 case XFS_REFCOUNT_ADJUST_COW_FREE:
1436 /* Removing a CoW reservation, there should be one extent. */
1437 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
1438 ext.rc_startblock == agbno, out_error);
1439 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
1440 ext.rc_blockcount == aglen, out_error);
1441 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
1442 ext.rc_refcount == 1, out_error);
1443
1444 ext.rc_refcount = 0;
1445 trace_xfs_refcount_modify_extent(cur->bc_mp,
1446 cur->bc_private.a.agno, &ext);
1447 error = xfs_refcount_delete(cur, &found_rec);
1448 if (error)
1449 goto out_error;
1450 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
1451 found_rec == 1, out_error);
1452 break;
1453 default:
1454 ASSERT(0);
1455 }
1456
1457 return error;
1458 out_error:
1459 trace_xfs_refcount_modify_extent_error(cur->bc_mp,
1460 cur->bc_private.a.agno, error, _RET_IP_);
1461 return error;
1462 }
1463
1464 /*
1465 * Add or remove refcount btree entries for CoW reservations.
1466 */
1467 STATIC int
1468 xfs_refcount_adjust_cow(
1469 struct xfs_btree_cur *cur,
1470 xfs_agblock_t agbno,
1471 xfs_extlen_t aglen,
1472 enum xfs_refc_adjust_op adj)
1473 {
1474 bool shape_changed;
1475 int error;
1476
1477 agbno += XFS_REFC_COW_START;
1478
1479 /*
1480 * Ensure that no rcextents cross the boundary of the adjustment range.
1481 */
1482 error = xfs_refcount_split_extent(cur, agbno, &shape_changed);
1483 if (error)
1484 goto out_error;
1485
1486 error = xfs_refcount_split_extent(cur, agbno + aglen, &shape_changed);
1487 if (error)
1488 goto out_error;
1489
1490 /*
1491 * Try to merge with the left or right extents of the range.
1492 */
1493 error = xfs_refcount_merge_extents(cur, &agbno, &aglen, adj,
1494 XFS_FIND_RCEXT_COW, &shape_changed);
1495 if (error)
1496 goto out_error;
1497
1498 /* Now that we've taken care of the ends, adjust the middle extents */
1499 error = xfs_refcount_adjust_cow_extents(cur, agbno, aglen, adj);
1500 if (error)
1501 goto out_error;
1502
1503 return 0;
1504
1505 out_error:
1506 trace_xfs_refcount_adjust_cow_error(cur->bc_mp, cur->bc_private.a.agno,
1507 error, _RET_IP_);
1508 return error;
1509 }
1510
1511 /*
1512 * Record a CoW allocation in the refcount btree.
1513 */
1514 STATIC int
1515 __xfs_refcount_cow_alloc(
1516 struct xfs_btree_cur *rcur,
1517 xfs_agblock_t agbno,
1518 xfs_extlen_t aglen)
1519 {
1520 trace_xfs_refcount_cow_increase(rcur->bc_mp, rcur->bc_private.a.agno,
1521 agbno, aglen);
1522
1523 /* Add refcount btree reservation */
1524 return xfs_refcount_adjust_cow(rcur, agbno, aglen,
1525 XFS_REFCOUNT_ADJUST_COW_ALLOC);
1526 }
1527
1528 /*
1529 * Remove a CoW allocation from the refcount btree.
1530 */
1531 STATIC int
1532 __xfs_refcount_cow_free(
1533 struct xfs_btree_cur *rcur,
1534 xfs_agblock_t agbno,
1535 xfs_extlen_t aglen)
1536 {
1537 trace_xfs_refcount_cow_decrease(rcur->bc_mp, rcur->bc_private.a.agno,
1538 agbno, aglen);
1539
1540 /* Remove refcount btree reservation */
1541 return xfs_refcount_adjust_cow(rcur, agbno, aglen,
1542 XFS_REFCOUNT_ADJUST_COW_FREE);
1543 }
1544
1545 /* Record a CoW staging extent in the refcount btree. */
1546 int
1547 xfs_refcount_alloc_cow_extent(
1548 struct xfs_trans *tp,
1549 xfs_fsblock_t fsb,
1550 xfs_extlen_t len)
1551 {
1552 struct xfs_mount *mp = tp->t_mountp;
1553 int error;
1554
1555 if (!xfs_sb_version_hasreflink(&mp->m_sb))
1556 return 0;
1557
1558 error = __xfs_refcount_add(tp, XFS_REFCOUNT_ALLOC_COW, fsb, len);
1559 if (error)
1560 return error;
1561
1562 /* Add rmap entry */
1563 return xfs_rmap_alloc_extent(tp, XFS_FSB_TO_AGNO(mp, fsb),
1564 XFS_FSB_TO_AGBNO(mp, fsb), len, XFS_RMAP_OWN_COW);
1565 }
1566
1567 /* Forget a CoW staging event in the refcount btree. */
1568 int
1569 xfs_refcount_free_cow_extent(
1570 struct xfs_trans *tp,
1571 xfs_fsblock_t fsb,
1572 xfs_extlen_t len)
1573 {
1574 struct xfs_mount *mp = tp->t_mountp;
1575 int error;
1576
1577 if (!xfs_sb_version_hasreflink(&mp->m_sb))
1578 return 0;
1579
1580 /* Remove rmap entry */
1581 error = xfs_rmap_free_extent(tp, XFS_FSB_TO_AGNO(mp, fsb),
1582 XFS_FSB_TO_AGBNO(mp, fsb), len, XFS_RMAP_OWN_COW);
1583 if (error)
1584 return error;
1585
1586 return __xfs_refcount_add(tp, XFS_REFCOUNT_FREE_COW, fsb, len);
1587 }
1588
1589 struct xfs_refcount_recovery {
1590 struct list_head rr_list;
1591 struct xfs_refcount_irec rr_rrec;
1592 };
1593
1594 /* Stuff an extent on the recovery list. */
1595 STATIC int
1596 xfs_refcount_recover_extent(
1597 struct xfs_btree_cur *cur,
1598 union xfs_btree_rec *rec,
1599 void *priv)
1600 {
1601 struct list_head *debris = priv;
1602 struct xfs_refcount_recovery *rr;
1603
1604 if (be32_to_cpu(rec->refc.rc_refcount) != 1)
1605 return -EFSCORRUPTED;
1606
1607 rr = kmem_alloc(sizeof(struct xfs_refcount_recovery), KM_SLEEP);
1608 xfs_refcount_btrec_to_irec(rec, &rr->rr_rrec);
1609 list_add_tail(&rr->rr_list, debris);
1610
1611 return 0;
1612 }
1613
1614 /* Find and remove leftover CoW reservations. */
1615 int
1616 xfs_refcount_recover_cow_leftovers(
1617 struct xfs_mount *mp,
1618 xfs_agnumber_t agno)
1619 {
1620 struct xfs_trans *tp;
1621 struct xfs_btree_cur *cur;
1622 struct xfs_buf *agbp;
1623 struct xfs_refcount_recovery *rr, *n;
1624 struct list_head debris;
1625 union xfs_btree_irec low;
1626 union xfs_btree_irec high;
1627 xfs_fsblock_t fsb;
1628 xfs_agblock_t agbno;
1629 int error;
1630
1631 if (mp->m_sb.sb_agblocks >= XFS_REFC_COW_START)
1632 return -EOPNOTSUPP;
1633
1634 INIT_LIST_HEAD(&debris);
1635
1636 /*
1637 * In this first part, we use an empty transaction to gather up
1638 * all the leftover CoW extents so that we can subsequently
1639 * delete them. The empty transaction is used to avoid
1640 * a buffer lock deadlock if there happens to be a loop in the
1641 * refcountbt because we're allowed to re-grab a buffer that is
1642 * already attached to our transaction. When we're done
1643 * recording the CoW debris we cancel the (empty) transaction
1644 * and everything goes away cleanly.
1645 */
1646 error = xfs_trans_alloc_empty(mp, &tp);
1647 if (error)
1648 return error;
1649
1650 error = xfs_alloc_read_agf(mp, tp, agno, 0, &agbp);
1651 if (error)
1652 goto out_trans;
1653 if (!agbp) {
1654 error = -ENOMEM;
1655 goto out_trans;
1656 }
1657 cur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno);
1658
1659 /* Find all the leftover CoW staging extents. */
1660 memset(&low, 0, sizeof(low));
1661 memset(&high, 0, sizeof(high));
1662 low.rc.rc_startblock = XFS_REFC_COW_START;
1663 high.rc.rc_startblock = -1U;
1664 error = xfs_btree_query_range(cur, &low, &high,
1665 xfs_refcount_recover_extent, &debris);
1666 xfs_btree_del_cursor(cur, error);
1667 xfs_trans_brelse(tp, agbp);
1668 xfs_trans_cancel(tp);
1669 if (error)
1670 goto out_free;
1671
1672 /* Now iterate the list to free the leftovers */
1673 list_for_each_entry_safe(rr, n, &debris, rr_list) {
1674 /* Set up transaction. */
1675 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0, 0, &tp);
1676 if (error)
1677 goto out_free;
1678
1679 trace_xfs_refcount_recover_extent(mp, agno, &rr->rr_rrec);
1680
1681 /* Free the orphan record */
1682 agbno = rr->rr_rrec.rc_startblock - XFS_REFC_COW_START;
1683 fsb = XFS_AGB_TO_FSB(mp, agno, agbno);
1684 error = xfs_refcount_free_cow_extent(tp, fsb,
1685 rr->rr_rrec.rc_blockcount);
1686 if (error)
1687 goto out_trans;
1688
1689 /* Free the block. */
1690 xfs_bmap_add_free(tp, fsb, rr->rr_rrec.rc_blockcount, NULL);
1691
1692 error = xfs_trans_commit(tp);
1693 if (error)
1694 goto out_free;
1695
1696 list_del(&rr->rr_list);
1697 kmem_free(rr);
1698 }
1699
1700 return error;
1701 out_trans:
1702 xfs_trans_cancel(tp);
1703 out_free:
1704 /* Free the leftover list */
1705 list_for_each_entry_safe(rr, n, &debris, rr_list) {
1706 list_del(&rr->rr_list);
1707 kmem_free(rr);
1708 }
1709 return error;
1710 }
1711
1712 /* Is there a record covering a given extent? */
1713 int
1714 xfs_refcount_has_record(
1715 struct xfs_btree_cur *cur,
1716 xfs_agblock_t bno,
1717 xfs_extlen_t len,
1718 bool *exists)
1719 {
1720 union xfs_btree_irec low;
1721 union xfs_btree_irec high;
1722
1723 memset(&low, 0, sizeof(low));
1724 low.rc.rc_startblock = bno;
1725 memset(&high, 0xFF, sizeof(high));
1726 high.rc.rc_startblock = bno + len - 1;
1727
1728 return xfs_btree_has_record(cur, &low, &high, exists);
1729 }
Linux with added FPC-III support