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(
25 return xchk_setup_ag_btree(sc, ip, false);
28 /* Reference count btree scrubber. */
31 * Confirming Reference Counts via Reverse Mappings
33 * We want to count the reverse mappings overlapping a refcount record
34 * (bno, len, refcount), allowing for the possibility that some of the
35 * overlap may come from smaller adjoining reverse mappings, while some
36 * comes from single extents which overlap the range entirely. The
37 * outer loop is as follows:
39 * 1. For all reverse mappings overlapping the refcount extent,
40 * a. If a given rmap completely overlaps, mark it as seen.
41 * b. Otherwise, record the fragment (in agbno order) for later
44 * Once we've seen all the rmaps, we know that for all blocks in the
45 * refcount record we want to find $refcount owners and we've already
46 * visited $seen extents that overlap all the blocks. Therefore, we
47 * need to find ($refcount - $seen) owners for every block in the
48 * extent; call that quantity $target_nr. Proceed as follows:
50 * 2. Pull the first $target_nr fragments from the list; all of them
51 * should start at or before the start of the extent.
52 * Call this subset of fragments the working set.
53 * 3. Until there are no more unprocessed fragments,
54 * a. Find the shortest fragments in the set and remove them.
55 * b. Note the block number of the end of these fragments.
56 * c. Pull the same number of fragments from the list. All of these
57 * fragments should start at the block number recorded in the
59 * d. Put those fragments in the set.
60 * 4. Check that there are $target_nr fragments remaining in the list,
61 * and that they all end at or beyond the end of the refcount extent.
63 * If the refcount is correct, all the check conditions in the algorithm
64 * should always hold true. If not, the refcount is incorrect.
66 struct xchk_refcnt_frag {
67 struct list_head list;
68 struct xfs_rmap_irec rm;
71 struct xchk_refcnt_check {
73 struct list_head fragments;
75 /* refcount extent we're examining */
80 /* number of owners seen */
85 * Decide if the given rmap is large enough that we can redeem it
86 * towards refcount verification now, or if it's a fragment, in
87 * which case we'll hang onto it in the hopes that we'll later
88 * discover that we've collected exactly the correct number of
89 * fragments as the refcountbt says we should have.
92 xchk_refcountbt_rmap_check(
93 struct xfs_btree_cur *cur,
94 struct xfs_rmap_irec *rec,
97 struct xchk_refcnt_check *refchk = priv;
98 struct xchk_refcnt_frag *frag;
99 xfs_agblock_t rm_last;
100 xfs_agblock_t rc_last;
103 if (xchk_should_terminate(refchk->sc, &error))
106 rm_last = rec->rm_startblock + rec->rm_blockcount - 1;
107 rc_last = refchk->bno + refchk->len - 1;
109 /* Confirm that a single-owner refc extent is a CoW stage. */
110 if (refchk->refcount == 1 && rec->rm_owner != XFS_RMAP_OWN_COW) {
111 xchk_btree_xref_set_corrupt(refchk->sc, cur, 0);
115 if (rec->rm_startblock <= refchk->bno && rm_last >= rc_last) {
117 * The rmap overlaps the refcount record, so we can confirm
118 * one refcount owner seen.
123 * This rmap covers only part of the refcount record, so
124 * save the fragment for later processing. If the rmapbt
125 * is healthy each rmap_irec we see will be in agbno order
126 * so we don't need insertion sort here.
128 frag = kmem_alloc(sizeof(struct xchk_refcnt_frag),
132 memcpy(&frag->rm, rec, sizeof(frag->rm));
133 list_add_tail(&frag->list, &refchk->fragments);
140 * Given a bunch of rmap fragments, iterate through them, keeping
141 * a running tally of the refcount. If this ever deviates from
142 * what we expect (which is the refcountbt's refcount minus the
143 * number of extents that totally covered the refcountbt extent),
144 * we have a refcountbt error.
147 xchk_refcountbt_process_rmap_fragments(
148 struct xchk_refcnt_check *refchk)
150 struct list_head worklist;
151 struct xchk_refcnt_frag *frag;
152 struct xchk_refcnt_frag *n;
155 xfs_agblock_t next_rbno;
157 xfs_nlink_t target_nr;
159 target_nr = refchk->refcount - refchk->seen;
164 * There are (refchk->rc.rc_refcount - refchk->nr refcount)
165 * references we haven't found yet. Pull that many off the
166 * fragment list and figure out where the smallest rmap ends
167 * (and therefore the next rmap should start). All the rmaps
168 * we pull off should start at or before the beginning of the
169 * refcount record's range.
171 INIT_LIST_HEAD(&worklist);
175 /* Make sure the fragments actually /are/ in agbno order. */
177 list_for_each_entry(frag, &refchk->fragments, list) {
178 if (frag->rm.rm_startblock < bno)
180 bno = frag->rm.rm_startblock;
184 * Find all the rmaps that start at or before the refc extent,
185 * and put them on the worklist.
187 list_for_each_entry_safe(frag, n, &refchk->fragments, list) {
188 if (frag->rm.rm_startblock > refchk->bno)
190 bno = frag->rm.rm_startblock + frag->rm.rm_blockcount;
193 list_move_tail(&frag->list, &worklist);
200 * We should have found exactly $target_nr rmap fragments starting
201 * at or before the refcount extent.
206 while (!list_empty(&refchk->fragments)) {
207 /* Discard any fragments ending at rbno from the worklist. */
209 next_rbno = NULLAGBLOCK;
210 list_for_each_entry_safe(frag, n, &worklist, list) {
211 bno = frag->rm.rm_startblock + frag->rm.rm_blockcount;
217 list_del(&frag->list);
222 /* Try to add nr rmaps starting at rbno to the worklist. */
223 list_for_each_entry_safe(frag, n, &refchk->fragments, list) {
224 bno = frag->rm.rm_startblock + frag->rm.rm_blockcount;
225 if (frag->rm.rm_startblock != rbno)
227 list_move_tail(&frag->list, &worklist);
236 * If we get here and nr > 0, this means that we added fewer
237 * items to the worklist than we discarded because the fragment
238 * list ran out of items. Therefore, we cannot maintain the
239 * required refcount. Something is wrong, so we're done.
248 * Make sure the last extent we processed ends at or beyond
249 * the end of the refcount extent.
251 if (rbno < refchk->bno + refchk->len)
254 /* Actually record us having seen the remaining refcount. */
255 refchk->seen = refchk->refcount;
257 /* Delete fragments and work list. */
258 list_for_each_entry_safe(frag, n, &worklist, list) {
259 list_del(&frag->list);
262 list_for_each_entry_safe(frag, n, &refchk->fragments, list) {
263 list_del(&frag->list);
268 /* Use the rmap entries covering this extent to verify the refcount. */
270 xchk_refcountbt_xref_rmap(
271 struct xfs_scrub *sc,
274 xfs_nlink_t refcount)
276 struct xchk_refcnt_check refchk = {
280 .refcount = refcount,
283 struct xfs_rmap_irec low;
284 struct xfs_rmap_irec high;
285 struct xchk_refcnt_frag *frag;
286 struct xchk_refcnt_frag *n;
289 if (!sc->sa.rmap_cur || xchk_skip_xref(sc->sm))
292 /* Cross-reference with the rmapbt to confirm the refcount. */
293 memset(&low, 0, sizeof(low));
294 low.rm_startblock = bno;
295 memset(&high, 0xFF, sizeof(high));
296 high.rm_startblock = bno + len - 1;
298 INIT_LIST_HEAD(&refchk.fragments);
299 error = xfs_rmap_query_range(sc->sa.rmap_cur, &low, &high,
300 &xchk_refcountbt_rmap_check, &refchk);
301 if (!xchk_should_check_xref(sc, &error, &sc->sa.rmap_cur))
304 xchk_refcountbt_process_rmap_fragments(&refchk);
305 if (refcount != refchk.seen)
306 xchk_btree_xref_set_corrupt(sc, sc->sa.rmap_cur, 0);
309 list_for_each_entry_safe(frag, n, &refchk.fragments, list) {
310 list_del(&frag->list);
315 /* Cross-reference with the other btrees. */
317 xchk_refcountbt_xref(
318 struct xfs_scrub *sc,
321 xfs_nlink_t refcount)
323 if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
326 xchk_xref_is_used_space(sc, agbno, len);
327 xchk_xref_is_not_inode_chunk(sc, agbno, len);
328 xchk_refcountbt_xref_rmap(sc, agbno, len, refcount);
331 /* Scrub a refcountbt record. */
334 struct xchk_btree *bs,
335 union xfs_btree_rec *rec)
337 struct xfs_mount *mp = bs->cur->bc_mp;
338 xfs_agblock_t *cow_blocks = bs->private;
339 xfs_agnumber_t agno = bs->cur->bc_ag.agno;
342 xfs_nlink_t refcount;
345 bno = be32_to_cpu(rec->refc.rc_startblock);
346 len = be32_to_cpu(rec->refc.rc_blockcount);
347 refcount = be32_to_cpu(rec->refc.rc_refcount);
349 /* Only CoW records can have refcount == 1. */
350 has_cowflag = (bno & XFS_REFC_COW_START);
351 if ((refcount == 1 && !has_cowflag) || (refcount != 1 && has_cowflag))
352 xchk_btree_set_corrupt(bs->sc, bs->cur, 0);
354 (*cow_blocks) += len;
356 /* Check the extent. */
357 bno &= ~XFS_REFC_COW_START;
358 if (bno + len <= bno ||
359 !xfs_verify_agbno(mp, agno, bno) ||
360 !xfs_verify_agbno(mp, agno, bno + len - 1))
361 xchk_btree_set_corrupt(bs->sc, bs->cur, 0);
364 xchk_btree_set_corrupt(bs->sc, bs->cur, 0);
366 xchk_refcountbt_xref(bs->sc, bno, len, refcount);
371 /* Make sure we have as many refc blocks as the rmap says. */
373 xchk_refcount_xref_rmap(
374 struct xfs_scrub *sc,
375 xfs_filblks_t cow_blocks)
377 xfs_extlen_t refcbt_blocks = 0;
378 xfs_filblks_t blocks;
381 if (!sc->sa.rmap_cur || xchk_skip_xref(sc->sm))
384 /* Check that we saw as many refcbt blocks as the rmap knows about. */
385 error = xfs_btree_count_blocks(sc->sa.refc_cur, &refcbt_blocks);
386 if (!xchk_btree_process_error(sc, sc->sa.refc_cur, 0, &error))
388 error = xchk_count_rmap_ownedby_ag(sc, sc->sa.rmap_cur,
389 &XFS_RMAP_OINFO_REFC, &blocks);
390 if (!xchk_should_check_xref(sc, &error, &sc->sa.rmap_cur))
392 if (blocks != refcbt_blocks)
393 xchk_btree_xref_set_corrupt(sc, sc->sa.rmap_cur, 0);
395 /* Check that we saw as many cow blocks as the rmap knows about. */
396 error = xchk_count_rmap_ownedby_ag(sc, sc->sa.rmap_cur,
397 &XFS_RMAP_OINFO_COW, &blocks);
398 if (!xchk_should_check_xref(sc, &error, &sc->sa.rmap_cur))
400 if (blocks != cow_blocks)
401 xchk_btree_xref_set_corrupt(sc, sc->sa.rmap_cur, 0);
404 /* Scrub the refcount btree for some AG. */
407 struct xfs_scrub *sc)
409 xfs_agblock_t cow_blocks = 0;
412 error = xchk_btree(sc, sc->sa.refc_cur, xchk_refcountbt_rec,
413 &XFS_RMAP_OINFO_REFC, &cow_blocks);
417 xchk_refcount_xref_rmap(sc, cow_blocks);
422 /* xref check that a cow staging extent is marked in the refcountbt. */
424 xchk_xref_is_cow_staging(
425 struct xfs_scrub *sc,
429 struct xfs_refcount_irec rc;
434 if (!sc->sa.refc_cur || xchk_skip_xref(sc->sm))
437 /* Find the CoW staging extent. */
438 error = xfs_refcount_lookup_le(sc->sa.refc_cur,
439 agbno + XFS_REFC_COW_START, &has_refcount);
440 if (!xchk_should_check_xref(sc, &error, &sc->sa.refc_cur))
443 xchk_btree_xref_set_corrupt(sc, sc->sa.refc_cur, 0);
447 error = xfs_refcount_get_rec(sc->sa.refc_cur, &rc, &has_refcount);
448 if (!xchk_should_check_xref(sc, &error, &sc->sa.refc_cur))
451 xchk_btree_xref_set_corrupt(sc, sc->sa.refc_cur, 0);
455 /* CoW flag must be set, refcount must be 1. */
456 has_cowflag = (rc.rc_startblock & XFS_REFC_COW_START);
457 if (!has_cowflag || rc.rc_refcount != 1)
458 xchk_btree_xref_set_corrupt(sc, sc->sa.refc_cur, 0);
460 /* Must be at least as long as what was passed in */
461 if (rc.rc_blockcount < len)
462 xchk_btree_xref_set_corrupt(sc, sc->sa.refc_cur, 0);
466 * xref check that the extent is not shared. Only file data blocks
467 * can have multiple owners.
470 xchk_xref_is_not_shared(
471 struct xfs_scrub *sc,
478 if (!sc->sa.refc_cur || xchk_skip_xref(sc->sm))
481 error = xfs_refcount_has_record(sc->sa.refc_cur, agbno, len, &shared);
482 if (!xchk_should_check_xref(sc, &error, &sc->sa.refc_cur))
485 xchk_btree_xref_set_corrupt(sc, sc->sa.refc_cur, 0);