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xfs: fix type usage
[linux/fpc-iii.git] / fs / xfs / libxfs / xfs_refcount.c
blob585b35d34142157863740d3b8cd437b37e49e05d
1 /*
2 * Copyright (C) 2016 Oracle. All Rights Reserved.
3 *
4 * Author: Darrick J. Wong <darrick.wong@oracle.com>
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version 2
9 * of the License, or (at your option) any later version.
10 *
11 * This program is distributed in the hope that it would be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
19 */
20 #include "xfs.h"
21 #include "xfs_fs.h"
22 #include "xfs_shared.h"
23 #include "xfs_format.h"
24 #include "xfs_log_format.h"
25 #include "xfs_trans_resv.h"
26 #include "xfs_sb.h"
27 #include "xfs_mount.h"
28 #include "xfs_defer.h"
29 #include "xfs_btree.h"
30 #include "xfs_bmap.h"
31 #include "xfs_refcount_btree.h"
32 #include "xfs_alloc.h"
33 #include "xfs_errortag.h"
34 #include "xfs_error.h"
35 #include "xfs_trace.h"
36 #include "xfs_cksum.h"
37 #include "xfs_trans.h"
38 #include "xfs_bit.h"
39 #include "xfs_refcount.h"
40 #include "xfs_rmap.h"
41
42 /* Allowable refcount adjustment amounts. */
43 enum xfs_refc_adjust_op {
44 XFS_REFCOUNT_ADJUST_INCREASE = 1,
45 XFS_REFCOUNT_ADJUST_DECREASE = -1,
46 XFS_REFCOUNT_ADJUST_COW_ALLOC = 0,
47 XFS_REFCOUNT_ADJUST_COW_FREE = -1,
48 };
49
50 STATIC int __xfs_refcount_cow_alloc(struct xfs_btree_cur *rcur,
51 xfs_agblock_t agbno, xfs_extlen_t aglen,
52 struct xfs_defer_ops *dfops);
53 STATIC int __xfs_refcount_cow_free(struct xfs_btree_cur *rcur,
54 xfs_agblock_t agbno, xfs_extlen_t aglen,
55 struct xfs_defer_ops *dfops);
56
57 /*
58 * Look up the first record less than or equal to [bno, len] in the btree
59 * given by cur.
60 */
61 int
62 xfs_refcount_lookup_le(
63 struct xfs_btree_cur *cur,
64 xfs_agblock_t bno,
65 int *stat)
66 {
67 trace_xfs_refcount_lookup(cur->bc_mp, cur->bc_private.a.agno, bno,
68 XFS_LOOKUP_LE);
69 cur->bc_rec.rc.rc_startblock = bno;
70 cur->bc_rec.rc.rc_blockcount = 0;
71 return xfs_btree_lookup(cur, XFS_LOOKUP_LE, stat);
72 }
73
74 /*
75 * Look up the first record greater than or equal to [bno, len] in the btree
76 * given by cur.
77 */
78 int
79 xfs_refcount_lookup_ge(
80 struct xfs_btree_cur *cur,
81 xfs_agblock_t bno,
82 int *stat)
83 {
84 trace_xfs_refcount_lookup(cur->bc_mp, cur->bc_private.a.agno, bno,
85 XFS_LOOKUP_GE);
86 cur->bc_rec.rc.rc_startblock = bno;
87 cur->bc_rec.rc.rc_blockcount = 0;
88 return xfs_btree_lookup(cur, XFS_LOOKUP_GE, stat);
89 }
90
91 /* Convert on-disk record to in-core format. */
92 static inline void
93 xfs_refcount_btrec_to_irec(
94 union xfs_btree_rec *rec,
95 struct xfs_refcount_irec *irec)
96 {
97 irec->rc_startblock = be32_to_cpu(rec->refc.rc_startblock);
98 irec->rc_blockcount = be32_to_cpu(rec->refc.rc_blockcount);
99 irec->rc_refcount = be32_to_cpu(rec->refc.rc_refcount);
100 }
101
102 /*
103 * Get the data from the pointed-to record.
104 */
105 int
106 xfs_refcount_get_rec(
107 struct xfs_btree_cur *cur,
108 struct xfs_refcount_irec *irec,
109 int *stat)
110 {
111 union xfs_btree_rec *rec;
112 int error;
113
114 error = xfs_btree_get_rec(cur, &rec, stat);
115 if (!error && *stat == 1) {
116 xfs_refcount_btrec_to_irec(rec, irec);
117 trace_xfs_refcount_get(cur->bc_mp, cur->bc_private.a.agno,
118 irec);
119 }
120 return error;
121 }
122
123 /*
124 * Update the record referred to by cur to the value given
125 * by [bno, len, refcount].
126 * This either works (return 0) or gets an EFSCORRUPTED error.
127 */
128 STATIC int
129 xfs_refcount_update(
130 struct xfs_btree_cur *cur,
131 struct xfs_refcount_irec *irec)
132 {
133 union xfs_btree_rec rec;
134 int error;
135
136 trace_xfs_refcount_update(cur->bc_mp, cur->bc_private.a.agno, irec);
137 rec.refc.rc_startblock = cpu_to_be32(irec->rc_startblock);
138 rec.refc.rc_blockcount = cpu_to_be32(irec->rc_blockcount);
139 rec.refc.rc_refcount = cpu_to_be32(irec->rc_refcount);
140 error = xfs_btree_update(cur, &rec);
141 if (error)
142 trace_xfs_refcount_update_error(cur->bc_mp,
143 cur->bc_private.a.agno, error, _RET_IP_);
144 return error;
145 }
146
147 /*
148 * Insert the record referred to by cur to the value given
149 * by [bno, len, refcount].
150 * This either works (return 0) or gets an EFSCORRUPTED error.
151 */
152 STATIC int
153 xfs_refcount_insert(
154 struct xfs_btree_cur *cur,
155 struct xfs_refcount_irec *irec,
156 int *i)
157 {
158 int error;
159
160 trace_xfs_refcount_insert(cur->bc_mp, cur->bc_private.a.agno, irec);
161 cur->bc_rec.rc.rc_startblock = irec->rc_startblock;
162 cur->bc_rec.rc.rc_blockcount = irec->rc_blockcount;
163 cur->bc_rec.rc.rc_refcount = irec->rc_refcount;
164 error = xfs_btree_insert(cur, i);
165 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, *i == 1, out_error);
166 out_error:
167 if (error)
168 trace_xfs_refcount_insert_error(cur->bc_mp,
169 cur->bc_private.a.agno, error, _RET_IP_);
170 return error;
171 }
172
173 /*
174 * Remove the record referred to by cur, then set the pointer to the spot
175 * where the record could be re-inserted, in case we want to increment or
176 * decrement the cursor.
177 * This either works (return 0) or gets an EFSCORRUPTED error.
178 */
179 STATIC int
180 xfs_refcount_delete(
181 struct xfs_btree_cur *cur,
182 int *i)
183 {
184 struct xfs_refcount_irec irec;
185 int found_rec;
186 int error;
187
188 error = xfs_refcount_get_rec(cur, &irec, &found_rec);
189 if (error)
190 goto out_error;
191 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
192 trace_xfs_refcount_delete(cur->bc_mp, cur->bc_private.a.agno, &irec);
193 error = xfs_btree_delete(cur, i);
194 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, *i == 1, out_error);
195 if (error)
196 goto out_error;
197 error = xfs_refcount_lookup_ge(cur, irec.rc_startblock, &found_rec);
198 out_error:
199 if (error)
200 trace_xfs_refcount_delete_error(cur->bc_mp,
201 cur->bc_private.a.agno, error, _RET_IP_);
202 return error;
203 }
204
205 /*
206 * Adjusting the Reference Count
207 *
208 * As stated elsewhere, the reference count btree (refcbt) stores
209 * >1 reference counts for extents of physical blocks. In this
210 * operation, we're either raising or lowering the reference count of
211 * some subrange stored in the tree:
212 *
213 * <------ adjustment range ------>
214 * ----+ +---+-----+ +--+--------+---------
215 * 2 | | 3 | 4 | |17| 55 | 10
216 * ----+ +---+-----+ +--+--------+---------
217 * X axis is physical blocks number;
218 * reference counts are the numbers inside the rectangles
219 *
220 * The first thing we need to do is to ensure that there are no
221 * refcount extents crossing either boundary of the range to be
222 * adjusted. For any extent that does cross a boundary, split it into
223 * two extents so that we can increment the refcount of one of the
224 * pieces later:
225 *
226 * <------ adjustment range ------>
227 * ----+ +---+-----+ +--+--------+----+----
228 * 2 | | 3 | 2 | |17| 55 | 10 | 10
229 * ----+ +---+-----+ +--+--------+----+----
230 *
231 * For this next step, let's assume that all the physical blocks in
232 * the adjustment range are mapped to a file and are therefore in use
233 * at least once. Therefore, we can infer that any gap in the
234 * refcount tree within the adjustment range represents a physical
235 * extent with refcount == 1:
236 *
237 * <------ adjustment range ------>
238 * ----+---+---+-----+-+--+--------+----+----
239 * 2 |"1"| 3 | 2 |1|17| 55 | 10 | 10
240 * ----+---+---+-----+-+--+--------+----+----
241 * ^
242 *
243 * For each extent that falls within the interval range, figure out
244 * which extent is to the left or the right of that extent. Now we
245 * have a left, current, and right extent. If the new reference count
246 * of the center extent enables us to merge left, center, and right
247 * into one record covering all three, do so. If the center extent is
248 * at the left end of the range, abuts the left extent, and its new
249 * reference count matches the left extent's record, then merge them.
250 * If the center extent is at the right end of the range, abuts the
251 * right extent, and the reference counts match, merge those. In the
252 * example, we can left merge (assuming an increment operation):
253 *
254 * <------ adjustment range ------>
255 * --------+---+-----+-+--+--------+----+----
256 * 2 | 3 | 2 |1|17| 55 | 10 | 10
257 * --------+---+-----+-+--+--------+----+----
258 * ^
259 *
260 * For all other extents within the range, adjust the reference count
261 * or delete it if the refcount falls below 2. If we were
262 * incrementing, the end result looks like this:
263 *
264 * <------ adjustment range ------>
265 * --------+---+-----+-+--+--------+----+----
266 * 2 | 4 | 3 |2|18| 56 | 11 | 10
267 * --------+---+-----+-+--+--------+----+----
268 *
269 * The result of a decrement operation looks as such:
270 *
271 * <------ adjustment range ------>
272 * ----+ +---+ +--+--------+----+----
273 * 2 | | 2 | |16| 54 | 9 | 10
274 * ----+ +---+ +--+--------+----+----
275 * DDDD 111111DD
276 *
277 * The blocks marked "D" are freed; the blocks marked "1" are only
278 * referenced once and therefore the record is removed from the
279 * refcount btree.
280 */
281
282 /* Next block after this extent. */
283 static inline xfs_agblock_t
284 xfs_refc_next(
285 struct xfs_refcount_irec *rc)
286 {
287 return rc->rc_startblock + rc->rc_blockcount;
288 }
289
290 /*
291 * Split a refcount extent that crosses agbno.
292 */
293 STATIC int
294 xfs_refcount_split_extent(
295 struct xfs_btree_cur *cur,
296 xfs_agblock_t agbno,
297 bool *shape_changed)
298 {
299 struct xfs_refcount_irec rcext, tmp;
300 int found_rec;
301 int error;
302
303 *shape_changed = false;
304 error = xfs_refcount_lookup_le(cur, agbno, &found_rec);
305 if (error)
306 goto out_error;
307 if (!found_rec)
308 return 0;
309
310 error = xfs_refcount_get_rec(cur, &rcext, &found_rec);
311 if (error)
312 goto out_error;
313 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
314 if (rcext.rc_startblock == agbno || xfs_refc_next(&rcext) <= agbno)
315 return 0;
316
317 *shape_changed = true;
318 trace_xfs_refcount_split_extent(cur->bc_mp, cur->bc_private.a.agno,
319 &rcext, agbno);
320
321 /* Establish the right extent. */
322 tmp = rcext;
323 tmp.rc_startblock = agbno;
324 tmp.rc_blockcount -= (agbno - rcext.rc_startblock);
325 error = xfs_refcount_update(cur, &tmp);
326 if (error)
327 goto out_error;
328
329 /* Insert the left extent. */
330 tmp = rcext;
331 tmp.rc_blockcount = agbno - rcext.rc_startblock;
332 error = xfs_refcount_insert(cur, &tmp, &found_rec);
333 if (error)
334 goto out_error;
335 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
336 return error;
337
338 out_error:
339 trace_xfs_refcount_split_extent_error(cur->bc_mp,
340 cur->bc_private.a.agno, error, _RET_IP_);
341 return error;
342 }
343
344 /*
345 * Merge the left, center, and right extents.
346 */
347 STATIC int
348 xfs_refcount_merge_center_extents(
349 struct xfs_btree_cur *cur,
350 struct xfs_refcount_irec *left,
351 struct xfs_refcount_irec *center,
352 struct xfs_refcount_irec *right,
353 unsigned long long extlen,
354 xfs_agblock_t *agbno,
355 xfs_extlen_t *aglen)
356 {
357 int error;
358 int found_rec;
359
360 trace_xfs_refcount_merge_center_extents(cur->bc_mp,
361 cur->bc_private.a.agno, left, center, right);
362
363 /*
364 * Make sure the center and right extents are not in the btree.
365 * If the center extent was synthesized, the first delete call
366 * removes the right extent and we skip the second deletion.
367 * If center and right were in the btree, then the first delete
368 * call removes the center and the second one removes the right
369 * extent.
370 */
371 error = xfs_refcount_lookup_ge(cur, center->rc_startblock,
372 &found_rec);
373 if (error)
374 goto out_error;
375 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
376
377 error = xfs_refcount_delete(cur, &found_rec);
378 if (error)
379 goto out_error;
380 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
381
382 if (center->rc_refcount > 1) {
383 error = xfs_refcount_delete(cur, &found_rec);
384 if (error)
385 goto out_error;
386 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
387 out_error);
388 }
389
390 /* Enlarge the left extent. */
391 error = xfs_refcount_lookup_le(cur, left->rc_startblock,
392 &found_rec);
393 if (error)
394 goto out_error;
395 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
396
397 left->rc_blockcount = extlen;
398 error = xfs_refcount_update(cur, left);
399 if (error)
400 goto out_error;
401
402 *aglen = 0;
403 return error;
404
405 out_error:
406 trace_xfs_refcount_merge_center_extents_error(cur->bc_mp,
407 cur->bc_private.a.agno, error, _RET_IP_);
408 return error;
409 }
410
411 /*
412 * Merge with the left extent.
413 */
414 STATIC int
415 xfs_refcount_merge_left_extent(
416 struct xfs_btree_cur *cur,
417 struct xfs_refcount_irec *left,
418 struct xfs_refcount_irec *cleft,
419 xfs_agblock_t *agbno,
420 xfs_extlen_t *aglen)
421 {
422 int error;
423 int found_rec;
424
425 trace_xfs_refcount_merge_left_extent(cur->bc_mp,
426 cur->bc_private.a.agno, left, cleft);
427
428 /* If the extent at agbno (cleft) wasn't synthesized, remove it. */
429 if (cleft->rc_refcount > 1) {
430 error = xfs_refcount_lookup_le(cur, cleft->rc_startblock,
431 &found_rec);
432 if (error)
433 goto out_error;
434 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
435 out_error);
436
437 error = xfs_refcount_delete(cur, &found_rec);
438 if (error)
439 goto out_error;
440 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
441 out_error);
442 }
443
444 /* Enlarge the left extent. */
445 error = xfs_refcount_lookup_le(cur, left->rc_startblock,
446 &found_rec);
447 if (error)
448 goto out_error;
449 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
450
451 left->rc_blockcount += cleft->rc_blockcount;
452 error = xfs_refcount_update(cur, left);
453 if (error)
454 goto out_error;
455
456 *agbno += cleft->rc_blockcount;
457 *aglen -= cleft->rc_blockcount;
458 return error;
459
460 out_error:
461 trace_xfs_refcount_merge_left_extent_error(cur->bc_mp,
462 cur->bc_private.a.agno, error, _RET_IP_);
463 return error;
464 }
465
466 /*
467 * Merge with the right extent.
468 */
469 STATIC int
470 xfs_refcount_merge_right_extent(
471 struct xfs_btree_cur *cur,
472 struct xfs_refcount_irec *right,
473 struct xfs_refcount_irec *cright,
474 xfs_agblock_t *agbno,
475 xfs_extlen_t *aglen)
476 {
477 int error;
478 int found_rec;
479
480 trace_xfs_refcount_merge_right_extent(cur->bc_mp,
481 cur->bc_private.a.agno, cright, right);
482
483 /*
484 * If the extent ending at agbno+aglen (cright) wasn't synthesized,
485 * remove it.
486 */
487 if (cright->rc_refcount > 1) {
488 error = xfs_refcount_lookup_le(cur, cright->rc_startblock,
489 &found_rec);
490 if (error)
491 goto out_error;
492 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
493 out_error);
494
495 error = xfs_refcount_delete(cur, &found_rec);
496 if (error)
497 goto out_error;
498 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
499 out_error);
500 }
501
502 /* Enlarge the right extent. */
503 error = xfs_refcount_lookup_le(cur, right->rc_startblock,
504 &found_rec);
505 if (error)
506 goto out_error;
507 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
508
509 right->rc_startblock -= cright->rc_blockcount;
510 right->rc_blockcount += cright->rc_blockcount;
511 error = xfs_refcount_update(cur, right);
512 if (error)
513 goto out_error;
514
515 *aglen -= cright->rc_blockcount;
516 return error;
517
518 out_error:
519 trace_xfs_refcount_merge_right_extent_error(cur->bc_mp,
520 cur->bc_private.a.agno, error, _RET_IP_);
521 return error;
522 }
523
524 #define XFS_FIND_RCEXT_SHARED 1
525 #define XFS_FIND_RCEXT_COW 2
526 /*
527 * Find the left extent and the one after it (cleft). This function assumes
528 * that we've already split any extent crossing agbno.
529 */
530 STATIC int
531 xfs_refcount_find_left_extents(
532 struct xfs_btree_cur *cur,
533 struct xfs_refcount_irec *left,
534 struct xfs_refcount_irec *cleft,
535 xfs_agblock_t agbno,
536 xfs_extlen_t aglen,
537 int flags)
538 {
539 struct xfs_refcount_irec tmp;
540 int error;
541 int found_rec;
542
543 left->rc_startblock = cleft->rc_startblock = NULLAGBLOCK;
544 error = xfs_refcount_lookup_le(cur, agbno - 1, &found_rec);
545 if (error)
546 goto out_error;
547 if (!found_rec)
548 return 0;
549
550 error = xfs_refcount_get_rec(cur, &tmp, &found_rec);
551 if (error)
552 goto out_error;
553 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
554
555 if (xfs_refc_next(&tmp) != agbno)
556 return 0;
557 if ((flags & XFS_FIND_RCEXT_SHARED) && tmp.rc_refcount < 2)
558 return 0;
559 if ((flags & XFS_FIND_RCEXT_COW) && tmp.rc_refcount > 1)
560 return 0;
561 /* We have a left extent; retrieve (or invent) the next right one */
562 *left = tmp;
563
564 error = xfs_btree_increment(cur, 0, &found_rec);
565 if (error)
566 goto out_error;
567 if (found_rec) {
568 error = xfs_refcount_get_rec(cur, &tmp, &found_rec);
569 if (error)
570 goto out_error;
571 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
572 out_error);
573
574 /* if tmp starts at the end of our range, just use that */
575 if (tmp.rc_startblock == agbno)
576 *cleft = tmp;
577 else {
578 /*
579 * There's a gap in the refcntbt at the start of the
580 * range we're interested in (refcount == 1) so
581 * synthesize the implied extent and pass it back.
582 * We assume here that the agbno/aglen range was
583 * passed in from a data fork extent mapping and
584 * therefore is allocated to exactly one owner.
585 */
586 cleft->rc_startblock = agbno;
587 cleft->rc_blockcount = min(aglen,
588 tmp.rc_startblock - agbno);
589 cleft->rc_refcount = 1;
590 }
591 } else {
592 /*
593 * No extents, so pretend that there's one covering the whole
594 * range.
595 */
596 cleft->rc_startblock = agbno;
597 cleft->rc_blockcount = aglen;
598 cleft->rc_refcount = 1;
599 }
600 trace_xfs_refcount_find_left_extent(cur->bc_mp, cur->bc_private.a.agno,
601 left, cleft, agbno);
602 return error;
603
604 out_error:
605 trace_xfs_refcount_find_left_extent_error(cur->bc_mp,
606 cur->bc_private.a.agno, error, _RET_IP_);
607 return error;
608 }
609
610 /*
611 * Find the right extent and the one before it (cright). This function
612 * assumes that we've already split any extents crossing agbno + aglen.
613 */
614 STATIC int
615 xfs_refcount_find_right_extents(
616 struct xfs_btree_cur *cur,
617 struct xfs_refcount_irec *right,
618 struct xfs_refcount_irec *cright,
619 xfs_agblock_t agbno,
620 xfs_extlen_t aglen,
621 int flags)
622 {
623 struct xfs_refcount_irec tmp;
624 int error;
625 int found_rec;
626
627 right->rc_startblock = cright->rc_startblock = NULLAGBLOCK;
628 error = xfs_refcount_lookup_ge(cur, agbno + aglen, &found_rec);
629 if (error)
630 goto out_error;
631 if (!found_rec)
632 return 0;
633
634 error = xfs_refcount_get_rec(cur, &tmp, &found_rec);
635 if (error)
636 goto out_error;
637 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
638
639 if (tmp.rc_startblock != agbno + aglen)
640 return 0;
641 if ((flags & XFS_FIND_RCEXT_SHARED) && tmp.rc_refcount < 2)
642 return 0;
643 if ((flags & XFS_FIND_RCEXT_COW) && tmp.rc_refcount > 1)
644 return 0;
645 /* We have a right extent; retrieve (or invent) the next left one */
646 *right = tmp;
647
648 error = xfs_btree_decrement(cur, 0, &found_rec);
649 if (error)
650 goto out_error;
651 if (found_rec) {
652 error = xfs_refcount_get_rec(cur, &tmp, &found_rec);
653 if (error)
654 goto out_error;
655 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
656 out_error);
657
658 /* if tmp ends at the end of our range, just use that */
659 if (xfs_refc_next(&tmp) == agbno + aglen)
660 *cright = tmp;
661 else {
662 /*
663 * There's a gap in the refcntbt at the end of the
664 * range we're interested in (refcount == 1) so
665 * create the implied extent and pass it back.
666 * We assume here that the agbno/aglen range was
667 * passed in from a data fork extent mapping and
668 * therefore is allocated to exactly one owner.
669 */
670 cright->rc_startblock = max(agbno, xfs_refc_next(&tmp));
671 cright->rc_blockcount = right->rc_startblock -
672 cright->rc_startblock;
673 cright->rc_refcount = 1;
674 }
675 } else {
676 /*
677 * No extents, so pretend that there's one covering the whole
678 * range.
679 */
680 cright->rc_startblock = agbno;
681 cright->rc_blockcount = aglen;
682 cright->rc_refcount = 1;
683 }
684 trace_xfs_refcount_find_right_extent(cur->bc_mp, cur->bc_private.a.agno,
685 cright, right, agbno + aglen);
686 return error;
687
688 out_error:
689 trace_xfs_refcount_find_right_extent_error(cur->bc_mp,
690 cur->bc_private.a.agno, error, _RET_IP_);
691 return error;
692 }
693
694 /* Is this extent valid? */
695 static inline bool
696 xfs_refc_valid(
697 struct xfs_refcount_irec *rc)
698 {
699 return rc->rc_startblock != NULLAGBLOCK;
700 }
701
702 /*
703 * Try to merge with any extents on the boundaries of the adjustment range.
704 */
705 STATIC int
706 xfs_refcount_merge_extents(
707 struct xfs_btree_cur *cur,
708 xfs_agblock_t *agbno,
709 xfs_extlen_t *aglen,
710 enum xfs_refc_adjust_op adjust,
711 int flags,
712 bool *shape_changed)
713 {
714 struct xfs_refcount_irec left = {0}, cleft = {0};
715 struct xfs_refcount_irec cright = {0}, right = {0};
716 int error;
717 unsigned long long ulen;
718 bool cequal;
719
720 *shape_changed = false;
721 /*
722 * Find the extent just below agbno [left], just above agbno [cleft],
723 * just below (agbno + aglen) [cright], and just above (agbno + aglen)
724 * [right].
725 */
726 error = xfs_refcount_find_left_extents(cur, &left, &cleft, *agbno,
727 *aglen, flags);
728 if (error)
729 return error;
730 error = xfs_refcount_find_right_extents(cur, &right, &cright, *agbno,
731 *aglen, flags);
732 if (error)
733 return error;
734
735 /* No left or right extent to merge; exit. */
736 if (!xfs_refc_valid(&left) && !xfs_refc_valid(&right))
737 return 0;
738
739 cequal = (cleft.rc_startblock == cright.rc_startblock) &&
740 (cleft.rc_blockcount == cright.rc_blockcount);
741
742 /* Try to merge left, cleft, and right. cleft must == cright. */
743 ulen = (unsigned long long)left.rc_blockcount + cleft.rc_blockcount +
744 right.rc_blockcount;
745 if (xfs_refc_valid(&left) && xfs_refc_valid(&right) &&
746 xfs_refc_valid(&cleft) && xfs_refc_valid(&cright) && cequal &&
747 left.rc_refcount == cleft.rc_refcount + adjust &&
748 right.rc_refcount == cleft.rc_refcount + adjust &&
749 ulen < MAXREFCEXTLEN) {
750 *shape_changed = true;
751 return xfs_refcount_merge_center_extents(cur, &left, &cleft,
752 &right, ulen, agbno, aglen);
753 }
754
755 /* Try to merge left and cleft. */
756 ulen = (unsigned long long)left.rc_blockcount + cleft.rc_blockcount;
757 if (xfs_refc_valid(&left) && xfs_refc_valid(&cleft) &&
758 left.rc_refcount == cleft.rc_refcount + adjust &&
759 ulen < MAXREFCEXTLEN) {
760 *shape_changed = true;
761 error = xfs_refcount_merge_left_extent(cur, &left, &cleft,
762 agbno, aglen);
763 if (error)
764 return error;
765
766 /*
767 * If we just merged left + cleft and cleft == cright,
768 * we no longer have a cright to merge with right. We're done.
769 */
770 if (cequal)
771 return 0;
772 }
773
774 /* Try to merge cright and right. */
775 ulen = (unsigned long long)right.rc_blockcount + cright.rc_blockcount;
776 if (xfs_refc_valid(&right) && xfs_refc_valid(&cright) &&
777 right.rc_refcount == cright.rc_refcount + adjust &&
778 ulen < MAXREFCEXTLEN) {
779 *shape_changed = true;
780 return xfs_refcount_merge_right_extent(cur, &right, &cright,
781 agbno, aglen);
782 }
783
784 return error;
785 }
786
787 /*
788 * XXX: This is a pretty hand-wavy estimate. The penalty for guessing
789 * true incorrectly is a shutdown FS; the penalty for guessing false
790 * incorrectly is more transaction rolls than might be necessary.
791 * Be conservative here.
792 */
793 static bool
794 xfs_refcount_still_have_space(
795 struct xfs_btree_cur *cur)
796 {
797 unsigned long overhead;
798
799 overhead = cur->bc_private.a.priv.refc.shape_changes *
800 xfs_allocfree_log_count(cur->bc_mp, 1);
801 overhead *= cur->bc_mp->m_sb.sb_blocksize;
802
803 /*
804 * Only allow 2 refcount extent updates per transaction if the
805 * refcount continue update "error" has been injected.
806 */
807 if (cur->bc_private.a.priv.refc.nr_ops > 2 &&
808 XFS_TEST_ERROR(false, cur->bc_mp,
809 XFS_ERRTAG_REFCOUNT_CONTINUE_UPDATE))
810 return false;
811
812 if (cur->bc_private.a.priv.refc.nr_ops == 0)
813 return true;
814 else if (overhead > cur->bc_tp->t_log_res)
815 return false;
816 return cur->bc_tp->t_log_res - overhead >
817 cur->bc_private.a.priv.refc.nr_ops * XFS_REFCOUNT_ITEM_OVERHEAD;
818 }
819
820 /*
821 * Adjust the refcounts of middle extents. At this point we should have
822 * split extents that crossed the adjustment range; merged with adjacent
823 * extents; and updated agbno/aglen to reflect the merges. Therefore,
824 * all we have to do is update the extents inside [agbno, agbno + aglen].
825 */
826 STATIC int
827 xfs_refcount_adjust_extents(
828 struct xfs_btree_cur *cur,
829 xfs_agblock_t *agbno,
830 xfs_extlen_t *aglen,
831 enum xfs_refc_adjust_op adj,
832 struct xfs_defer_ops *dfops,
833 struct xfs_owner_info *oinfo)
834 {
835 struct xfs_refcount_irec ext, tmp;
836 int error;
837 int found_rec, found_tmp;
838 xfs_fsblock_t fsbno;
839
840 /* Merging did all the work already. */
841 if (*aglen == 0)
842 return 0;
843
844 error = xfs_refcount_lookup_ge(cur, *agbno, &found_rec);
845 if (error)
846 goto out_error;
847
848 while (*aglen > 0 && xfs_refcount_still_have_space(cur)) {
849 error = xfs_refcount_get_rec(cur, &ext, &found_rec);
850 if (error)
851 goto out_error;
852 if (!found_rec) {
853 ext.rc_startblock = cur->bc_mp->m_sb.sb_agblocks;
854 ext.rc_blockcount = 0;
855 ext.rc_refcount = 0;
856 }
857
858 /*
859 * Deal with a hole in the refcount tree; if a file maps to
860 * these blocks and there's no refcountbt record, pretend that
861 * there is one with refcount == 1.
862 */
863 if (ext.rc_startblock != *agbno) {
864 tmp.rc_startblock = *agbno;
865 tmp.rc_blockcount = min(*aglen,
866 ext.rc_startblock - *agbno);
867 tmp.rc_refcount = 1 + adj;
868 trace_xfs_refcount_modify_extent(cur->bc_mp,
869 cur->bc_private.a.agno, &tmp);
870
871 /*
872 * Either cover the hole (increment) or
873 * delete the range (decrement).
874 */
875 if (tmp.rc_refcount) {
876 error = xfs_refcount_insert(cur, &tmp,
877 &found_tmp);
878 if (error)
879 goto out_error;
880 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
881 found_tmp == 1, out_error);
882 cur->bc_private.a.priv.refc.nr_ops++;
883 } else {
884 fsbno = XFS_AGB_TO_FSB(cur->bc_mp,
885 cur->bc_private.a.agno,
886 tmp.rc_startblock);
887 xfs_bmap_add_free(cur->bc_mp, dfops, fsbno,
888 tmp.rc_blockcount, oinfo);
889 }
890
891 (*agbno) += tmp.rc_blockcount;
892 (*aglen) -= tmp.rc_blockcount;
893
894 error = xfs_refcount_lookup_ge(cur, *agbno,
895 &found_rec);
896 if (error)
897 goto out_error;
898 }
899
900 /* Stop if there's nothing left to modify */
901 if (*aglen == 0 || !xfs_refcount_still_have_space(cur))
902 break;
903
904 /*
905 * Adjust the reference count and either update the tree
906 * (incr) or free the blocks (decr).
907 */
908 if (ext.rc_refcount == MAXREFCOUNT)
909 goto skip;
910 ext.rc_refcount += adj;
911 trace_xfs_refcount_modify_extent(cur->bc_mp,
912 cur->bc_private.a.agno, &ext);
913 if (ext.rc_refcount > 1) {
914 error = xfs_refcount_update(cur, &ext);
915 if (error)
916 goto out_error;
917 cur->bc_private.a.priv.refc.nr_ops++;
918 } else if (ext.rc_refcount == 1) {
919 error = xfs_refcount_delete(cur, &found_rec);
920 if (error)
921 goto out_error;
922 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
923 found_rec == 1, out_error);
924 cur->bc_private.a.priv.refc.nr_ops++;
925 goto advloop;
926 } else {
927 fsbno = XFS_AGB_TO_FSB(cur->bc_mp,
928 cur->bc_private.a.agno,
929 ext.rc_startblock);
930 xfs_bmap_add_free(cur->bc_mp, dfops, fsbno,
931 ext.rc_blockcount, oinfo);
932 }
933
934 skip:
935 error = xfs_btree_increment(cur, 0, &found_rec);
936 if (error)
937 goto out_error;
938
939 advloop:
940 (*agbno) += ext.rc_blockcount;
941 (*aglen) -= ext.rc_blockcount;
942 }
943
944 return error;
945 out_error:
946 trace_xfs_refcount_modify_extent_error(cur->bc_mp,
947 cur->bc_private.a.agno, error, _RET_IP_);
948 return error;
949 }
950
951 /* Adjust the reference count of a range of AG blocks. */
952 STATIC int
953 xfs_refcount_adjust(
954 struct xfs_btree_cur *cur,
955 xfs_agblock_t agbno,
956 xfs_extlen_t aglen,
957 xfs_agblock_t *new_agbno,
958 xfs_extlen_t *new_aglen,
959 enum xfs_refc_adjust_op adj,
960 struct xfs_defer_ops *dfops,
961 struct xfs_owner_info *oinfo)
962 {
963 bool shape_changed;
964 int shape_changes = 0;
965 int error;
966
967 *new_agbno = agbno;
968 *new_aglen = aglen;
969 if (adj == XFS_REFCOUNT_ADJUST_INCREASE)
970 trace_xfs_refcount_increase(cur->bc_mp, cur->bc_private.a.agno,
971 agbno, aglen);
972 else
973 trace_xfs_refcount_decrease(cur->bc_mp, cur->bc_private.a.agno,
974 agbno, aglen);
975
976 /*
977 * Ensure that no rcextents cross the boundary of the adjustment range.
978 */
979 error = xfs_refcount_split_extent(cur, agbno, &shape_changed);
980 if (error)
981 goto out_error;
982 if (shape_changed)
983 shape_changes++;
984
985 error = xfs_refcount_split_extent(cur, agbno + aglen, &shape_changed);
986 if (error)
987 goto out_error;
988 if (shape_changed)
989 shape_changes++;
990
991 /*
992 * Try to merge with the left or right extents of the range.
993 */
994 error = xfs_refcount_merge_extents(cur, new_agbno, new_aglen, adj,
995 XFS_FIND_RCEXT_SHARED, &shape_changed);
996 if (error)
997 goto out_error;
998 if (shape_changed)
999 shape_changes++;
1000 if (shape_changes)
1001 cur->bc_private.a.priv.refc.shape_changes++;
1002
1003 /* Now that we've taken care of the ends, adjust the middle extents */
1004 error = xfs_refcount_adjust_extents(cur, new_agbno, new_aglen,
1005 adj, dfops, oinfo);
1006 if (error)
1007 goto out_error;
1008
1009 return 0;
1010
1011 out_error:
1012 trace_xfs_refcount_adjust_error(cur->bc_mp, cur->bc_private.a.agno,
1013 error, _RET_IP_);
1014 return error;
1015 }
1016
1017 /* Clean up after calling xfs_refcount_finish_one. */
1018 void
1019 xfs_refcount_finish_one_cleanup(
1020 struct xfs_trans *tp,
1021 struct xfs_btree_cur *rcur,
1022 int error)
1023 {
1024 struct xfs_buf *agbp;
1025
1026 if (rcur == NULL)
1027 return;
1028 agbp = rcur->bc_private.a.agbp;
1029 xfs_btree_del_cursor(rcur, error ? XFS_BTREE_ERROR : XFS_BTREE_NOERROR);
1030 if (error)
1031 xfs_trans_brelse(tp, agbp);
1032 }
1033
1034 /*
1035 * Process one of the deferred refcount operations. We pass back the
1036 * btree cursor to maintain our lock on the btree between calls.
1037 * This saves time and eliminates a buffer deadlock between the
1038 * superblock and the AGF because we'll always grab them in the same
1039 * order.
1040 */
1041 int
1042 xfs_refcount_finish_one(
1043 struct xfs_trans *tp,
1044 struct xfs_defer_ops *dfops,
1045 enum xfs_refcount_intent_type type,
1046 xfs_fsblock_t startblock,
1047 xfs_extlen_t blockcount,
1048 xfs_fsblock_t *new_fsb,
1049 xfs_extlen_t *new_len,
1050 struct xfs_btree_cur **pcur)
1051 {
1052 struct xfs_mount *mp = tp->t_mountp;
1053 struct xfs_btree_cur *rcur;
1054 struct xfs_buf *agbp = NULL;
1055 int error = 0;
1056 xfs_agnumber_t agno;
1057 xfs_agblock_t bno;
1058 xfs_agblock_t new_agbno;
1059 unsigned long nr_ops = 0;
1060 int shape_changes = 0;
1061
1062 agno = XFS_FSB_TO_AGNO(mp, startblock);
1063 ASSERT(agno != NULLAGNUMBER);
1064 bno = XFS_FSB_TO_AGBNO(mp, startblock);
1065
1066 trace_xfs_refcount_deferred(mp, XFS_FSB_TO_AGNO(mp, startblock),
1067 type, XFS_FSB_TO_AGBNO(mp, startblock),
1068 blockcount);
1069
1070 if (XFS_TEST_ERROR(false, mp,
1071 XFS_ERRTAG_REFCOUNT_FINISH_ONE))
1072 return -EIO;
1073
1074 /*
1075 * If we haven't gotten a cursor or the cursor AG doesn't match
1076 * the startblock, get one now.
1077 */
1078 rcur = *pcur;
1079 if (rcur != NULL && rcur->bc_private.a.agno != agno) {
1080 nr_ops = rcur->bc_private.a.priv.refc.nr_ops;
1081 shape_changes = rcur->bc_private.a.priv.refc.shape_changes;
1082 xfs_refcount_finish_one_cleanup(tp, rcur, 0);
1083 rcur = NULL;
1084 *pcur = NULL;
1085 }
1086 if (rcur == NULL) {
1087 error = xfs_alloc_read_agf(tp->t_mountp, tp, agno,
1088 XFS_ALLOC_FLAG_FREEING, &agbp);
1089 if (error)
1090 return error;
1091 if (!agbp)
1092 return -EFSCORRUPTED;
1093
1094 rcur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno, dfops);
1095 if (!rcur) {
1096 error = -ENOMEM;
1097 goto out_cur;
1098 }
1099 rcur->bc_private.a.priv.refc.nr_ops = nr_ops;
1100 rcur->bc_private.a.priv.refc.shape_changes = shape_changes;
1101 }
1102 *pcur = rcur;
1103
1104 switch (type) {
1105 case XFS_REFCOUNT_INCREASE:
1106 error = xfs_refcount_adjust(rcur, bno, blockcount, &new_agbno,
1107 new_len, XFS_REFCOUNT_ADJUST_INCREASE, dfops, NULL);
1108 *new_fsb = XFS_AGB_TO_FSB(mp, agno, new_agbno);
1109 break;
1110 case XFS_REFCOUNT_DECREASE:
1111 error = xfs_refcount_adjust(rcur, bno, blockcount, &new_agbno,
1112 new_len, XFS_REFCOUNT_ADJUST_DECREASE, dfops, NULL);
1113 *new_fsb = XFS_AGB_TO_FSB(mp, agno, new_agbno);
1114 break;
1115 case XFS_REFCOUNT_ALLOC_COW:
1116 *new_fsb = startblock + blockcount;
1117 *new_len = 0;
1118 error = __xfs_refcount_cow_alloc(rcur, bno, blockcount, dfops);
1119 break;
1120 case XFS_REFCOUNT_FREE_COW:
1121 *new_fsb = startblock + blockcount;
1122 *new_len = 0;
1123 error = __xfs_refcount_cow_free(rcur, bno, blockcount, dfops);
1124 break;
1125 default:
1126 ASSERT(0);
1127 error = -EFSCORRUPTED;
1128 }
1129 if (!error && *new_len > 0)
1130 trace_xfs_refcount_finish_one_leftover(mp, agno, type,
1131 bno, blockcount, new_agbno, *new_len);
1132 return error;
1133
1134 out_cur:
1135 xfs_trans_brelse(tp, agbp);
1136
1137 return error;
1138 }
1139
1140 /*
1141 * Record a refcount intent for later processing.
1142 */
1143 static int
1144 __xfs_refcount_add(
1145 struct xfs_mount *mp,
1146 struct xfs_defer_ops *dfops,
1147 enum xfs_refcount_intent_type type,
1148 xfs_fsblock_t startblock,
1149 xfs_extlen_t blockcount)
1150 {
1151 struct xfs_refcount_intent *ri;
1152
1153 trace_xfs_refcount_defer(mp, XFS_FSB_TO_AGNO(mp, startblock),
1154 type, XFS_FSB_TO_AGBNO(mp, startblock),
1155 blockcount);
1156
1157 ri = kmem_alloc(sizeof(struct xfs_refcount_intent),
1158 KM_SLEEP | KM_NOFS);
1159 INIT_LIST_HEAD(&ri->ri_list);
1160 ri->ri_type = type;
1161 ri->ri_startblock = startblock;
1162 ri->ri_blockcount = blockcount;
1163
1164 xfs_defer_add(dfops, XFS_DEFER_OPS_TYPE_REFCOUNT, &ri->ri_list);
1165 return 0;
1166 }
1167
1168 /*
1169 * Increase the reference count of the blocks backing a file's extent.
1170 */
1171 int
1172 xfs_refcount_increase_extent(
1173 struct xfs_mount *mp,
1174 struct xfs_defer_ops *dfops,
1175 struct xfs_bmbt_irec *PREV)
1176 {
1177 if (!xfs_sb_version_hasreflink(&mp->m_sb))
1178 return 0;
1179
1180 return __xfs_refcount_add(mp, dfops, XFS_REFCOUNT_INCREASE,
1181 PREV->br_startblock, PREV->br_blockcount);
1182 }
1183
1184 /*
1185 * Decrease the reference count of the blocks backing a file's extent.
1186 */
1187 int
1188 xfs_refcount_decrease_extent(
1189 struct xfs_mount *mp,
1190 struct xfs_defer_ops *dfops,
1191 struct xfs_bmbt_irec *PREV)
1192 {
1193 if (!xfs_sb_version_hasreflink(&mp->m_sb))
1194 return 0;
1195
1196 return __xfs_refcount_add(mp, dfops, XFS_REFCOUNT_DECREASE,
1197 PREV->br_startblock, PREV->br_blockcount);
1198 }
1199
1200 /*
1201 * Given an AG extent, find the lowest-numbered run of shared blocks
1202 * within that range and return the range in fbno/flen. If
1203 * find_end_of_shared is set, return the longest contiguous extent of
1204 * shared blocks; if not, just return the first extent we find. If no
1205 * shared blocks are found, fbno and flen will be set to NULLAGBLOCK
1206 * and 0, respectively.
1207 */
1208 int
1209 xfs_refcount_find_shared(
1210 struct xfs_btree_cur *cur,
1211 xfs_agblock_t agbno,
1212 xfs_extlen_t aglen,
1213 xfs_agblock_t *fbno,
1214 xfs_extlen_t *flen,
1215 bool find_end_of_shared)
1216 {
1217 struct xfs_refcount_irec tmp;
1218 int i;
1219 int have;
1220 int error;
1221
1222 trace_xfs_refcount_find_shared(cur->bc_mp, cur->bc_private.a.agno,
1223 agbno, aglen);
1224
1225 /* By default, skip the whole range */
1226 *fbno = NULLAGBLOCK;
1227 *flen = 0;
1228
1229 /* Try to find a refcount extent that crosses the start */
1230 error = xfs_refcount_lookup_le(cur, agbno, &have);
1231 if (error)
1232 goto out_error;
1233 if (!have) {
1234 /* No left extent, look at the next one */
1235 error = xfs_btree_increment(cur, 0, &have);
1236 if (error)
1237 goto out_error;
1238 if (!have)
1239 goto done;
1240 }
1241 error = xfs_refcount_get_rec(cur, &tmp, &i);
1242 if (error)
1243 goto out_error;
1244 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, i == 1, out_error);
1245
1246 /* If the extent ends before the start, look at the next one */
1247 if (tmp.rc_startblock + tmp.rc_blockcount <= agbno) {
1248 error = xfs_btree_increment(cur, 0, &have);
1249 if (error)
1250 goto out_error;
1251 if (!have)
1252 goto done;
1253 error = xfs_refcount_get_rec(cur, &tmp, &i);
1254 if (error)
1255 goto out_error;
1256 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, i == 1, out_error);
1257 }
1258
1259 /* If the extent starts after the range we want, bail out */
1260 if (tmp.rc_startblock >= agbno + aglen)
1261 goto done;
1262
1263 /* We found the start of a shared extent! */
1264 if (tmp.rc_startblock < agbno) {
1265 tmp.rc_blockcount -= (agbno - tmp.rc_startblock);
1266 tmp.rc_startblock = agbno;
1267 }
1268
1269 *fbno = tmp.rc_startblock;
1270 *flen = min(tmp.rc_blockcount, agbno + aglen - *fbno);
1271 if (!find_end_of_shared)
1272 goto done;
1273
1274 /* Otherwise, find the end of this shared extent */
1275 while (*fbno + *flen < agbno + aglen) {
1276 error = xfs_btree_increment(cur, 0, &have);
1277 if (error)
1278 goto out_error;
1279 if (!have)
1280 break;
1281 error = xfs_refcount_get_rec(cur, &tmp, &i);
1282 if (error)
1283 goto out_error;
1284 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, i == 1, out_error);
1285 if (tmp.rc_startblock >= agbno + aglen ||
1286 tmp.rc_startblock != *fbno + *flen)
1287 break;
1288 *flen = min(*flen + tmp.rc_blockcount, agbno + aglen - *fbno);
1289 }
1290
1291 done:
1292 trace_xfs_refcount_find_shared_result(cur->bc_mp,
1293 cur->bc_private.a.agno, *fbno, *flen);
1294
1295 out_error:
1296 if (error)
1297 trace_xfs_refcount_find_shared_error(cur->bc_mp,
1298 cur->bc_private.a.agno, error, _RET_IP_);
1299 return error;
1300 }
1301
1302 /*
1303 * Recovering CoW Blocks After a Crash
1304 *
1305 * Due to the way that the copy on write mechanism works, there's a window of
1306 * opportunity in which we can lose track of allocated blocks during a crash.
1307 * Because CoW uses delayed allocation in the in-core CoW fork, writeback
1308 * causes blocks to be allocated and stored in the CoW fork. The blocks are
1309 * no longer in the free space btree but are not otherwise recorded anywhere
1310 * until the write completes and the blocks are mapped into the file. A crash
1311 * in between allocation and remapping results in the replacement blocks being
1312 * lost. This situation is exacerbated by the CoW extent size hint because
1313 * allocations can hang around for long time.
1314 *
1315 * However, there is a place where we can record these allocations before they
1316 * become mappings -- the reference count btree. The btree does not record
1317 * extents with refcount == 1, so we can record allocations with a refcount of
1318 * 1. Blocks being used for CoW writeout cannot be shared, so there should be
1319 * no conflict with shared block records. These mappings should be created
1320 * when we allocate blocks to the CoW fork and deleted when they're removed
1321 * from the CoW fork.
1322 *
1323 * Minor nit: records for in-progress CoW allocations and records for shared
1324 * extents must never be merged, to preserve the property that (except for CoW
1325 * allocations) there are no refcount btree entries with refcount == 1. The
1326 * only time this could potentially happen is when unsharing a block that's
1327 * adjacent to CoW allocations, so we must be careful to avoid this.
1328 *
1329 * At mount time we recover lost CoW allocations by searching the refcount
1330 * btree for these refcount == 1 mappings. These represent CoW allocations
1331 * that were in progress at the time the filesystem went down, so we can free
1332 * them to get the space back.
1333 *
1334 * This mechanism is superior to creating EFIs for unmapped CoW extents for
1335 * several reasons -- first, EFIs pin the tail of the log and would have to be
1336 * periodically relogged to avoid filling up the log. Second, CoW completions
1337 * will have to file an EFD and create new EFIs for whatever remains in the
1338 * CoW fork; this partially takes care of (1) but extent-size reservations
1339 * will have to periodically relog even if there's no writeout in progress.
1340 * This can happen if the CoW extent size hint is set, which you really want.
1341 * Third, EFIs cannot currently be automatically relogged into newer
1342 * transactions to advance the log tail. Fourth, stuffing the log full of
1343 * EFIs places an upper bound on the number of CoW allocations that can be
1344 * held filesystem-wide at any given time. Recording them in the refcount
1345 * btree doesn't require us to maintain any state in memory and doesn't pin
1346 * the log.
1347 */
1348 /*
1349 * Adjust the refcounts of CoW allocations. These allocations are "magic"
1350 * in that they're not referenced anywhere else in the filesystem, so we
1351 * stash them in the refcount btree with a refcount of 1 until either file
1352 * remapping (or CoW cancellation) happens.
1353 */
1354 STATIC int
1355 xfs_refcount_adjust_cow_extents(
1356 struct xfs_btree_cur *cur,
1357 xfs_agblock_t agbno,
1358 xfs_extlen_t aglen,
1359 enum xfs_refc_adjust_op adj,
1360 struct xfs_defer_ops *dfops,
1361 struct xfs_owner_info *oinfo)
1362 {
1363 struct xfs_refcount_irec ext, tmp;
1364 int error;
1365 int found_rec, found_tmp;
1366
1367 if (aglen == 0)
1368 return 0;
1369
1370 /* Find any overlapping refcount records */
1371 error = xfs_refcount_lookup_ge(cur, agbno, &found_rec);
1372 if (error)
1373 goto out_error;
1374 error = xfs_refcount_get_rec(cur, &ext, &found_rec);
1375 if (error)
1376 goto out_error;
1377 if (!found_rec) {
1378 ext.rc_startblock = cur->bc_mp->m_sb.sb_agblocks +
1379 XFS_REFC_COW_START;
1380 ext.rc_blockcount = 0;
1381 ext.rc_refcount = 0;
1382 }
1383
1384 switch (adj) {
1385 case XFS_REFCOUNT_ADJUST_COW_ALLOC:
1386 /* Adding a CoW reservation, there should be nothing here. */
1387 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
1388 ext.rc_startblock >= agbno + aglen, out_error);
1389
1390 tmp.rc_startblock = agbno;
1391 tmp.rc_blockcount = aglen;
1392 tmp.rc_refcount = 1;
1393 trace_xfs_refcount_modify_extent(cur->bc_mp,
1394 cur->bc_private.a.agno, &tmp);
1395
1396 error = xfs_refcount_insert(cur, &tmp,
1397 &found_tmp);
1398 if (error)
1399 goto out_error;
1400 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
1401 found_tmp == 1, out_error);
1402 break;
1403 case XFS_REFCOUNT_ADJUST_COW_FREE:
1404 /* Removing a CoW reservation, there should be one extent. */
1405 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
1406 ext.rc_startblock == agbno, out_error);
1407 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
1408 ext.rc_blockcount == aglen, out_error);
1409 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
1410 ext.rc_refcount == 1, out_error);
1411
1412 ext.rc_refcount = 0;
1413 trace_xfs_refcount_modify_extent(cur->bc_mp,
1414 cur->bc_private.a.agno, &ext);
1415 error = xfs_refcount_delete(cur, &found_rec);
1416 if (error)
1417 goto out_error;
1418 XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
1419 found_rec == 1, out_error);
1420 break;
1421 default:
1422 ASSERT(0);
1423 }
1424
1425 return error;
1426 out_error:
1427 trace_xfs_refcount_modify_extent_error(cur->bc_mp,
1428 cur->bc_private.a.agno, error, _RET_IP_);
1429 return error;
1430 }
1431
1432 /*
1433 * Add or remove refcount btree entries for CoW reservations.
1434 */
1435 STATIC int
1436 xfs_refcount_adjust_cow(
1437 struct xfs_btree_cur *cur,
1438 xfs_agblock_t agbno,
1439 xfs_extlen_t aglen,
1440 enum xfs_refc_adjust_op adj,
1441 struct xfs_defer_ops *dfops)
1442 {
1443 bool shape_changed;
1444 int error;
1445
1446 agbno += XFS_REFC_COW_START;
1447
1448 /*
1449 * Ensure that no rcextents cross the boundary of the adjustment range.
1450 */
1451 error = xfs_refcount_split_extent(cur, agbno, &shape_changed);
1452 if (error)
1453 goto out_error;
1454
1455 error = xfs_refcount_split_extent(cur, agbno + aglen, &shape_changed);
1456 if (error)
1457 goto out_error;
1458
1459 /*
1460 * Try to merge with the left or right extents of the range.
1461 */
1462 error = xfs_refcount_merge_extents(cur, &agbno, &aglen, adj,
1463 XFS_FIND_RCEXT_COW, &shape_changed);
1464 if (error)
1465 goto out_error;
1466
1467 /* Now that we've taken care of the ends, adjust the middle extents */
1468 error = xfs_refcount_adjust_cow_extents(cur, agbno, aglen, adj,
1469 dfops, NULL);
1470 if (error)
1471 goto out_error;
1472
1473 return 0;
1474
1475 out_error:
1476 trace_xfs_refcount_adjust_cow_error(cur->bc_mp, cur->bc_private.a.agno,
1477 error, _RET_IP_);
1478 return error;
1479 }
1480
1481 /*
1482 * Record a CoW allocation in the refcount btree.
1483 */
1484 STATIC int
1485 __xfs_refcount_cow_alloc(
1486 struct xfs_btree_cur *rcur,
1487 xfs_agblock_t agbno,
1488 xfs_extlen_t aglen,
1489 struct xfs_defer_ops *dfops)
1490 {
1491 int error;
1492
1493 trace_xfs_refcount_cow_increase(rcur->bc_mp, rcur->bc_private.a.agno,
1494 agbno, aglen);
1495
1496 /* Add refcount btree reservation */
1497 error = xfs_refcount_adjust_cow(rcur, agbno, aglen,
1498 XFS_REFCOUNT_ADJUST_COW_ALLOC, dfops);
1499 if (error)
1500 return error;
1501
1502 /* Add rmap entry */
1503 if (xfs_sb_version_hasrmapbt(&rcur->bc_mp->m_sb)) {
1504 error = xfs_rmap_alloc_extent(rcur->bc_mp, dfops,
1505 rcur->bc_private.a.agno,
1506 agbno, aglen, XFS_RMAP_OWN_COW);
1507 if (error)
1508 return error;
1509 }
1510
1511 return error;
1512 }
1513
1514 /*
1515 * Remove a CoW allocation from the refcount btree.
1516 */
1517 STATIC int
1518 __xfs_refcount_cow_free(
1519 struct xfs_btree_cur *rcur,
1520 xfs_agblock_t agbno,
1521 xfs_extlen_t aglen,
1522 struct xfs_defer_ops *dfops)
1523 {
1524 int error;
1525
1526 trace_xfs_refcount_cow_decrease(rcur->bc_mp, rcur->bc_private.a.agno,
1527 agbno, aglen);
1528
1529 /* Remove refcount btree reservation */
1530 error = xfs_refcount_adjust_cow(rcur, agbno, aglen,
1531 XFS_REFCOUNT_ADJUST_COW_FREE, dfops);
1532 if (error)
1533 return error;
1534
1535 /* Remove rmap entry */
1536 if (xfs_sb_version_hasrmapbt(&rcur->bc_mp->m_sb)) {
1537 error = xfs_rmap_free_extent(rcur->bc_mp, dfops,
1538 rcur->bc_private.a.agno,
1539 agbno, aglen, XFS_RMAP_OWN_COW);
1540 if (error)
1541 return error;
1542 }
1543
1544 return error;
1545 }
1546
1547 /* Record a CoW staging extent in the refcount btree. */
1548 int
1549 xfs_refcount_alloc_cow_extent(
1550 struct xfs_mount *mp,
1551 struct xfs_defer_ops *dfops,
1552 xfs_fsblock_t fsb,
1553 xfs_extlen_t len)
1554 {
1555 if (!xfs_sb_version_hasreflink(&mp->m_sb))
1556 return 0;
1557
1558 return __xfs_refcount_add(mp, dfops, XFS_REFCOUNT_ALLOC_COW,
1559 fsb, len);
1560 }
1561
1562 /* Forget a CoW staging event in the refcount btree. */
1563 int
1564 xfs_refcount_free_cow_extent(
1565 struct xfs_mount *mp,
1566 struct xfs_defer_ops *dfops,
1567 xfs_fsblock_t fsb,
1568 xfs_extlen_t len)
1569 {
1570 if (!xfs_sb_version_hasreflink(&mp->m_sb))
1571 return 0;
1572
1573 return __xfs_refcount_add(mp, dfops, XFS_REFCOUNT_FREE_COW,
1574 fsb, len);
1575 }
1576
1577 struct xfs_refcount_recovery {
1578 struct list_head rr_list;
1579 struct xfs_refcount_irec rr_rrec;
1580 };
1581
1582 /* Stuff an extent on the recovery list. */
1583 STATIC int
1584 xfs_refcount_recover_extent(
1585 struct xfs_btree_cur *cur,
1586 union xfs_btree_rec *rec,
1587 void *priv)
1588 {
1589 struct list_head *debris = priv;
1590 struct xfs_refcount_recovery *rr;
1591
1592 if (be32_to_cpu(rec->refc.rc_refcount) != 1)
1593 return -EFSCORRUPTED;
1594
1595 rr = kmem_alloc(sizeof(struct xfs_refcount_recovery), KM_SLEEP);
1596 xfs_refcount_btrec_to_irec(rec, &rr->rr_rrec);
1597 list_add_tail(&rr->rr_list, debris);
1598
1599 return 0;
1600 }
1601
1602 /* Find and remove leftover CoW reservations. */
1603 int
1604 xfs_refcount_recover_cow_leftovers(
1605 struct xfs_mount *mp,
1606 xfs_agnumber_t agno)
1607 {
1608 struct xfs_trans *tp;
1609 struct xfs_btree_cur *cur;
1610 struct xfs_buf *agbp;
1611 struct xfs_refcount_recovery *rr, *n;
1612 struct list_head debris;
1613 union xfs_btree_irec low;
1614 union xfs_btree_irec high;
1615 struct xfs_defer_ops dfops;
1616 xfs_fsblock_t fsb;
1617 xfs_agblock_t agbno;
1618 int error;
1619
1620 if (mp->m_sb.sb_agblocks >= XFS_REFC_COW_START)
1621 return -EOPNOTSUPP;
1622
1623 INIT_LIST_HEAD(&debris);
1624
1625 /*
1626 * In this first part, we use an empty transaction to gather up
1627 * all the leftover CoW extents so that we can subsequently
1628 * delete them. The empty transaction is used to avoid
1629 * a buffer lock deadlock if there happens to be a loop in the
1630 * refcountbt because we're allowed to re-grab a buffer that is
1631 * already attached to our transaction. When we're done
1632 * recording the CoW debris we cancel the (empty) transaction
1633 * and everything goes away cleanly.
1634 */
1635 error = xfs_trans_alloc_empty(mp, &tp);
1636 if (error)
1637 return error;
1638
1639 error = xfs_alloc_read_agf(mp, tp, agno, 0, &agbp);
1640 if (error)
1641 goto out_trans;
1642 if (!agbp) {
1643 error = -ENOMEM;
1644 goto out_trans;
1645 }
1646 cur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno, NULL);
1647
1648 /* Find all the leftover CoW staging extents. */
1649 memset(&low, 0, sizeof(low));
1650 memset(&high, 0, sizeof(high));
1651 low.rc.rc_startblock = XFS_REFC_COW_START;
1652 high.rc.rc_startblock = -1U;
1653 error = xfs_btree_query_range(cur, &low, &high,
1654 xfs_refcount_recover_extent, &debris);
1655 if (error)
1656 goto out_cursor;
1657 xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
1658 xfs_trans_brelse(tp, agbp);
1659 xfs_trans_cancel(tp);
1660
1661 /* Now iterate the list to free the leftovers */
1662 list_for_each_entry_safe(rr, n, &debris, rr_list) {
1663 /* Set up transaction. */
1664 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0, 0, &tp);
1665 if (error)
1666 goto out_free;
1667
1668 trace_xfs_refcount_recover_extent(mp, agno, &rr->rr_rrec);
1669
1670 /* Free the orphan record */
1671 xfs_defer_init(&dfops, &fsb);
1672 agbno = rr->rr_rrec.rc_startblock - XFS_REFC_COW_START;
1673 fsb = XFS_AGB_TO_FSB(mp, agno, agbno);
1674 error = xfs_refcount_free_cow_extent(mp, &dfops, fsb,
1675 rr->rr_rrec.rc_blockcount);
1676 if (error)
1677 goto out_defer;
1678
1679 /* Free the block. */
1680 xfs_bmap_add_free(mp, &dfops, fsb,
1681 rr->rr_rrec.rc_blockcount, NULL);
1682
1683 error = xfs_defer_finish(&tp, &dfops);
1684 if (error)
1685 goto out_defer;
1686
1687 error = xfs_trans_commit(tp);
1688 if (error)
1689 goto out_free;
1690
1691 list_del(&rr->rr_list);
1692 kmem_free(rr);
1693 }
1694
1695 return error;
1696 out_defer:
1697 xfs_defer_cancel(&dfops);
1698 out_trans:
1699 xfs_trans_cancel(tp);
1700 out_free:
1701 /* Free the leftover list */
1702 list_for_each_entry_safe(rr, n, &debris, rr_list) {
1703 list_del(&rr->rr_list);
1704 kmem_free(rr);
1705 }
1706 return error;
1707
1708 out_cursor:
1709 xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
1710 xfs_trans_brelse(tp, agbp);
1711 goto out_trans;
1712 }
Linux with added FPC-III support