1 // SPDX-License-Identifier: GPL-2.0+
3 * Copyright (C) 2017 Oracle. All Rights Reserved.
4 * Author: Darrick J. Wong <darrick.wong@oracle.com>
8 #include "xfs_shared.h"
9 #include "xfs_format.h"
10 #include "xfs_btree.h"
12 #include "xfs_refcount.h"
13 #include "scrub/scrub.h"
14 #include "scrub/common.h"
15 #include "scrub/btree.h"
18 * Set us up to scrub reference count btrees.
21 xchk_setup_ag_refcountbt(
24 return xchk_setup_ag_btree(sc, false);
27 /* Reference count btree scrubber. */
30 * Confirming Reference Counts via Reverse Mappings
32 * We want to count the reverse mappings overlapping a refcount record
33 * (bno, len, refcount), allowing for the possibility that some of the
34 * overlap may come from smaller adjoining reverse mappings, while some
35 * comes from single extents which overlap the range entirely. The
36 * outer loop is as follows:
38 * 1. For all reverse mappings overlapping the refcount extent,
39 * a. If a given rmap completely overlaps, mark it as seen.
40 * b. Otherwise, record the fragment (in agbno order) for later
43 * Once we've seen all the rmaps, we know that for all blocks in the
44 * refcount record we want to find $refcount owners and we've already
45 * visited $seen extents that overlap all the blocks. Therefore, we
46 * need to find ($refcount - $seen) owners for every block in the
47 * extent; call that quantity $target_nr. Proceed as follows:
49 * 2. Pull the first $target_nr fragments from the list; all of them
50 * should start at or before the start of the extent.
51 * Call this subset of fragments the working set.
52 * 3. Until there are no more unprocessed fragments,
53 * a. Find the shortest fragments in the set and remove them.
54 * b. Note the block number of the end of these fragments.
55 * c. Pull the same number of fragments from the list. All of these
56 * fragments should start at the block number recorded in the
58 * d. Put those fragments in the set.
59 * 4. Check that there are $target_nr fragments remaining in the list,
60 * and that they all end at or beyond the end of the refcount extent.
62 * If the refcount is correct, all the check conditions in the algorithm
63 * should always hold true. If not, the refcount is incorrect.
65 struct xchk_refcnt_frag {
66 struct list_head list;
67 struct xfs_rmap_irec rm;
70 struct xchk_refcnt_check {
72 struct list_head fragments;
74 /* refcount extent we're examining */
79 /* number of owners seen */
84 * Decide if the given rmap is large enough that we can redeem it
85 * towards refcount verification now, or if it's a fragment, in
86 * which case we'll hang onto it in the hopes that we'll later
87 * discover that we've collected exactly the correct number of
88 * fragments as the refcountbt says we should have.
91 xchk_refcountbt_rmap_check(
92 struct xfs_btree_cur *cur,
93 struct xfs_rmap_irec *rec,
96 struct xchk_refcnt_check *refchk = priv;
97 struct xchk_refcnt_frag *frag;
98 xfs_agblock_t rm_last;
99 xfs_agblock_t rc_last;
102 if (xchk_should_terminate(refchk->sc, &error))
105 rm_last = rec->rm_startblock + rec->rm_blockcount - 1;
106 rc_last = refchk->bno + refchk->len - 1;
108 /* Confirm that a single-owner refc extent is a CoW stage. */
109 if (refchk->refcount == 1 && rec->rm_owner != XFS_RMAP_OWN_COW) {
110 xchk_btree_xref_set_corrupt(refchk->sc, cur, 0);
114 if (rec->rm_startblock <= refchk->bno && rm_last >= rc_last) {
116 * The rmap overlaps the refcount record, so we can confirm
117 * one refcount owner seen.
122 * This rmap covers only part of the refcount record, so
123 * save the fragment for later processing. If the rmapbt
124 * is healthy each rmap_irec we see will be in agbno order
125 * so we don't need insertion sort here.
127 frag = kmem_alloc(sizeof(struct xchk_refcnt_frag),
131 memcpy(&frag->rm, rec, sizeof(frag->rm));
132 list_add_tail(&frag->list, &refchk->fragments);
139 * Given a bunch of rmap fragments, iterate through them, keeping
140 * a running tally of the refcount. If this ever deviates from
141 * what we expect (which is the refcountbt's refcount minus the
142 * number of extents that totally covered the refcountbt extent),
143 * we have a refcountbt error.
146 xchk_refcountbt_process_rmap_fragments(
147 struct xchk_refcnt_check *refchk)
149 struct list_head worklist;
150 struct xchk_refcnt_frag *frag;
151 struct xchk_refcnt_frag *n;
154 xfs_agblock_t next_rbno;
156 xfs_nlink_t target_nr;
158 target_nr = refchk->refcount - refchk->seen;
163 * There are (refchk->rc.rc_refcount - refchk->nr refcount)
164 * references we haven't found yet. Pull that many off the
165 * fragment list and figure out where the smallest rmap ends
166 * (and therefore the next rmap should start). All the rmaps
167 * we pull off should start at or before the beginning of the
168 * refcount record's range.
170 INIT_LIST_HEAD(&worklist);
173 /* Make sure the fragments actually /are/ in agbno order. */
175 list_for_each_entry(frag, &refchk->fragments, list) {
176 if (frag->rm.rm_startblock < bno)
178 bno = frag->rm.rm_startblock;
182 * Find all the rmaps that start at or before the refc extent,
183 * and put them on the worklist.
186 list_for_each_entry_safe(frag, n, &refchk->fragments, list) {
187 if (frag->rm.rm_startblock > refchk->bno || nr > target_nr)
189 bno = frag->rm.rm_startblock + frag->rm.rm_blockcount;
192 list_move_tail(&frag->list, &worklist);
197 * We should have found exactly $target_nr rmap fragments starting
198 * at or before the refcount extent.
203 while (!list_empty(&refchk->fragments)) {
204 /* Discard any fragments ending at rbno from the worklist. */
206 next_rbno = NULLAGBLOCK;
207 list_for_each_entry_safe(frag, n, &worklist, list) {
208 bno = frag->rm.rm_startblock + frag->rm.rm_blockcount;
214 list_del(&frag->list);
219 /* Try to add nr rmaps starting at rbno to the worklist. */
220 list_for_each_entry_safe(frag, n, &refchk->fragments, list) {
221 bno = frag->rm.rm_startblock + frag->rm.rm_blockcount;
222 if (frag->rm.rm_startblock != rbno)
224 list_move_tail(&frag->list, &worklist);
233 * If we get here and nr > 0, this means that we added fewer
234 * items to the worklist than we discarded because the fragment
235 * list ran out of items. Therefore, we cannot maintain the
236 * required refcount. Something is wrong, so we're done.
245 * Make sure the last extent we processed ends at or beyond
246 * the end of the refcount extent.
248 if (rbno < refchk->bno + refchk->len)
251 /* Actually record us having seen the remaining refcount. */
252 refchk->seen = refchk->refcount;
254 /* Delete fragments and work list. */
255 list_for_each_entry_safe(frag, n, &worklist, list) {
256 list_del(&frag->list);
259 list_for_each_entry_safe(frag, n, &refchk->fragments, list) {
260 list_del(&frag->list);
265 /* Use the rmap entries covering this extent to verify the refcount. */
267 xchk_refcountbt_xref_rmap(
268 struct xfs_scrub *sc,
271 xfs_nlink_t refcount)
273 struct xchk_refcnt_check refchk = {
277 .refcount = refcount,
280 struct xfs_rmap_irec low;
281 struct xfs_rmap_irec high;
282 struct xchk_refcnt_frag *frag;
283 struct xchk_refcnt_frag *n;
286 if (!sc->sa.rmap_cur || xchk_skip_xref(sc->sm))
289 /* Cross-reference with the rmapbt to confirm the refcount. */
290 memset(&low, 0, sizeof(low));
291 low.rm_startblock = bno;
292 memset(&high, 0xFF, sizeof(high));
293 high.rm_startblock = bno + len - 1;
295 INIT_LIST_HEAD(&refchk.fragments);
296 error = xfs_rmap_query_range(sc->sa.rmap_cur, &low, &high,
297 &xchk_refcountbt_rmap_check, &refchk);
298 if (!xchk_should_check_xref(sc, &error, &sc->sa.rmap_cur))
301 xchk_refcountbt_process_rmap_fragments(&refchk);
302 if (refcount != refchk.seen)
303 xchk_btree_xref_set_corrupt(sc, sc->sa.rmap_cur, 0);
306 list_for_each_entry_safe(frag, n, &refchk.fragments, list) {
307 list_del(&frag->list);
312 /* Cross-reference with the other btrees. */
314 xchk_refcountbt_xref(
315 struct xfs_scrub *sc,
318 xfs_nlink_t refcount)
320 if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
323 xchk_xref_is_used_space(sc, agbno, len);
324 xchk_xref_is_not_inode_chunk(sc, agbno, len);
325 xchk_refcountbt_xref_rmap(sc, agbno, len, refcount);
328 /* Scrub a refcountbt record. */
331 struct xchk_btree *bs,
332 union xfs_btree_rec *rec)
334 struct xfs_mount *mp = bs->cur->bc_mp;
335 xfs_agblock_t *cow_blocks = bs->private;
336 xfs_agnumber_t agno = bs->cur->bc_ag.agno;
339 xfs_nlink_t refcount;
342 bno = be32_to_cpu(rec->refc.rc_startblock);
343 len = be32_to_cpu(rec->refc.rc_blockcount);
344 refcount = be32_to_cpu(rec->refc.rc_refcount);
346 /* Only CoW records can have refcount == 1. */
347 has_cowflag = (bno & XFS_REFC_COW_START);
348 if ((refcount == 1 && !has_cowflag) || (refcount != 1 && has_cowflag))
349 xchk_btree_set_corrupt(bs->sc, bs->cur, 0);
351 (*cow_blocks) += len;
353 /* Check the extent. */
354 bno &= ~XFS_REFC_COW_START;
355 if (bno + len <= bno ||
356 !xfs_verify_agbno(mp, agno, bno) ||
357 !xfs_verify_agbno(mp, agno, bno + len - 1))
358 xchk_btree_set_corrupt(bs->sc, bs->cur, 0);
361 xchk_btree_set_corrupt(bs->sc, bs->cur, 0);
363 xchk_refcountbt_xref(bs->sc, bno, len, refcount);
368 /* Make sure we have as many refc blocks as the rmap says. */
370 xchk_refcount_xref_rmap(
371 struct xfs_scrub *sc,
372 xfs_filblks_t cow_blocks)
374 xfs_extlen_t refcbt_blocks = 0;
375 xfs_filblks_t blocks;
378 if (!sc->sa.rmap_cur || xchk_skip_xref(sc->sm))
381 /* Check that we saw as many refcbt blocks as the rmap knows about. */
382 error = xfs_btree_count_blocks(sc->sa.refc_cur, &refcbt_blocks);
383 if (!xchk_btree_process_error(sc, sc->sa.refc_cur, 0, &error))
385 error = xchk_count_rmap_ownedby_ag(sc, sc->sa.rmap_cur,
386 &XFS_RMAP_OINFO_REFC, &blocks);
387 if (!xchk_should_check_xref(sc, &error, &sc->sa.rmap_cur))
389 if (blocks != refcbt_blocks)
390 xchk_btree_xref_set_corrupt(sc, sc->sa.rmap_cur, 0);
392 /* Check that we saw as many cow blocks as the rmap knows about. */
393 error = xchk_count_rmap_ownedby_ag(sc, sc->sa.rmap_cur,
394 &XFS_RMAP_OINFO_COW, &blocks);
395 if (!xchk_should_check_xref(sc, &error, &sc->sa.rmap_cur))
397 if (blocks != cow_blocks)
398 xchk_btree_xref_set_corrupt(sc, sc->sa.rmap_cur, 0);
401 /* Scrub the refcount btree for some AG. */
404 struct xfs_scrub *sc)
406 xfs_agblock_t cow_blocks = 0;
409 error = xchk_btree(sc, sc->sa.refc_cur, xchk_refcountbt_rec,
410 &XFS_RMAP_OINFO_REFC, &cow_blocks);
414 xchk_refcount_xref_rmap(sc, cow_blocks);
419 /* xref check that a cow staging extent is marked in the refcountbt. */
421 xchk_xref_is_cow_staging(
422 struct xfs_scrub *sc,
426 struct xfs_refcount_irec rc;
431 if (!sc->sa.refc_cur || xchk_skip_xref(sc->sm))
434 /* Find the CoW staging extent. */
435 error = xfs_refcount_lookup_le(sc->sa.refc_cur,
436 agbno + XFS_REFC_COW_START, &has_refcount);
437 if (!xchk_should_check_xref(sc, &error, &sc->sa.refc_cur))
440 xchk_btree_xref_set_corrupt(sc, sc->sa.refc_cur, 0);
444 error = xfs_refcount_get_rec(sc->sa.refc_cur, &rc, &has_refcount);
445 if (!xchk_should_check_xref(sc, &error, &sc->sa.refc_cur))
448 xchk_btree_xref_set_corrupt(sc, sc->sa.refc_cur, 0);
452 /* CoW flag must be set, refcount must be 1. */
453 has_cowflag = (rc.rc_startblock & XFS_REFC_COW_START);
454 if (!has_cowflag || rc.rc_refcount != 1)
455 xchk_btree_xref_set_corrupt(sc, sc->sa.refc_cur, 0);
457 /* Must be at least as long as what was passed in */
458 if (rc.rc_blockcount < len)
459 xchk_btree_xref_set_corrupt(sc, sc->sa.refc_cur, 0);
463 * xref check that the extent is not shared. Only file data blocks
464 * can have multiple owners.
467 xchk_xref_is_not_shared(
468 struct xfs_scrub *sc,
475 if (!sc->sa.refc_cur || xchk_skip_xref(sc->sm))
478 error = xfs_refcount_has_record(sc->sa.refc_cur, agbno, len, &shared);
479 if (!xchk_should_check_xref(sc, &error, &sc->sa.refc_cur))
482 xchk_btree_xref_set_corrupt(sc, sc->sa.refc_cur, 0);