--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2021-2024 Oracle. All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_btree.h"
+#include "xfs_rmap.h"
+#include "xfs_refcount.h"
+#include "xfs_inode.h"
+#include "xfs_rtbitmap.h"
+#include "xfs_rtgroup.h"
+#include "xfs_metafile.h"
+#include "xfs_rtrefcount_btree.h"
+#include "scrub/scrub.h"
+#include "scrub/common.h"
+#include "scrub/btree.h"
+
+/* Set us up with the realtime refcount metadata locked. */
+int
+xchk_setup_rtrefcountbt(
+ struct xfs_scrub *sc)
+{
+ int error;
+
+ if (xchk_need_intent_drain(sc))
+ xchk_fsgates_enable(sc, XCHK_FSGATES_DRAIN);
+
+ error = xchk_rtgroup_init(sc, sc->sm->sm_agno, &sc->sr);
+ if (error)
+ return error;
+
+ error = xchk_setup_rt(sc);
+ if (error)
+ return error;
+
+ error = xchk_install_live_inode(sc,
+ sc->sr.rtg->rtg_inodes[XFS_RTGI_REFCOUNT]);
+ if (error)
+ return error;
+
+ return xchk_rtgroup_lock(sc, &sc->sr, XCHK_RTGLOCK_ALL);
+}
+
+/* Realtime Reference count btree scrubber. */
+
+/*
+ * Confirming Reference Counts via Reverse Mappings
+ *
+ * We want to count the reverse mappings overlapping a refcount record
+ * (bno, len, refcount), allowing for the possibility that some of the
+ * overlap may come from smaller adjoining reverse mappings, while some
+ * comes from single extents which overlap the range entirely. The
+ * outer loop is as follows:
+ *
+ * 1. For all reverse mappings overlapping the refcount extent,
+ * a. If a given rmap completely overlaps, mark it as seen.
+ * b. Otherwise, record the fragment (in agbno order) for later
+ * processing.
+ *
+ * Once we've seen all the rmaps, we know that for all blocks in the
+ * refcount record we want to find $refcount owners and we've already
+ * visited $seen extents that overlap all the blocks. Therefore, we
+ * need to find ($refcount - $seen) owners for every block in the
+ * extent; call that quantity $target_nr. Proceed as follows:
+ *
+ * 2. Pull the first $target_nr fragments from the list; all of them
+ * should start at or before the start of the extent.
+ * Call this subset of fragments the working set.
+ * 3. Until there are no more unprocessed fragments,
+ * a. Find the shortest fragments in the set and remove them.
+ * b. Note the block number of the end of these fragments.
+ * c. Pull the same number of fragments from the list. All of these
+ * fragments should start at the block number recorded in the
+ * previous step.
+ * d. Put those fragments in the set.
+ * 4. Check that there are $target_nr fragments remaining in the list,
+ * and that they all end at or beyond the end of the refcount extent.
+ *
+ * If the refcount is correct, all the check conditions in the algorithm
+ * should always hold true. If not, the refcount is incorrect.
+ */
+struct xchk_rtrefcnt_frag {
+ struct list_head list;
+ struct xfs_rmap_irec rm;
+};
+
+struct xchk_rtrefcnt_check {
+ struct xfs_scrub *sc;
+ struct list_head fragments;
+
+ /* refcount extent we're examining */
+ xfs_rgblock_t bno;
+ xfs_extlen_t len;
+ xfs_nlink_t refcount;
+
+ /* number of owners seen */
+ xfs_nlink_t seen;
+};
+
+/*
+ * Decide if the given rmap is large enough that we can redeem it
+ * towards refcount verification now, or if it's a fragment, in
+ * which case we'll hang onto it in the hopes that we'll later
+ * discover that we've collected exactly the correct number of
+ * fragments as the rtrefcountbt says we should have.
+ */
+STATIC int
+xchk_rtrefcountbt_rmap_check(
+ struct xfs_btree_cur *cur,
+ const struct xfs_rmap_irec *rec,
+ void *priv)
+{
+ struct xchk_rtrefcnt_check *refchk = priv;
+ struct xchk_rtrefcnt_frag *frag;
+ xfs_rgblock_t rm_last;
+ xfs_rgblock_t rc_last;
+ int error = 0;
+
+ if (xchk_should_terminate(refchk->sc, &error))
+ return error;
+
+ rm_last = rec->rm_startblock + rec->rm_blockcount - 1;
+ rc_last = refchk->bno + refchk->len - 1;
+
+ /* Confirm that a single-owner refc extent is a CoW stage. */
+ if (refchk->refcount == 1 && rec->rm_owner != XFS_RMAP_OWN_COW) {
+ xchk_btree_xref_set_corrupt(refchk->sc, cur, 0);
+ return 0;
+ }
+
+ if (rec->rm_startblock <= refchk->bno && rm_last >= rc_last) {
+ /*
+ * The rmap overlaps the refcount record, so we can confirm
+ * one refcount owner seen.
+ */
+ refchk->seen++;
+ } else {
+ /*
+ * This rmap covers only part of the refcount record, so
+ * save the fragment for later processing. If the rmapbt
+ * is healthy each rmap_irec we see will be in agbno order
+ * so we don't need insertion sort here.
+ */
+ frag = kmalloc(sizeof(struct xchk_rtrefcnt_frag),
+ XCHK_GFP_FLAGS);
+ if (!frag)
+ return -ENOMEM;
+ memcpy(&frag->rm, rec, sizeof(frag->rm));
+ list_add_tail(&frag->list, &refchk->fragments);
+ }
+
+ return 0;
+}
+
+/*
+ * Given a bunch of rmap fragments, iterate through them, keeping
+ * a running tally of the refcount. If this ever deviates from
+ * what we expect (which is the rtrefcountbt's refcount minus the
+ * number of extents that totally covered the rtrefcountbt extent),
+ * we have a rtrefcountbt error.
+ */
+STATIC void
+xchk_rtrefcountbt_process_rmap_fragments(
+ struct xchk_rtrefcnt_check *refchk)
+{
+ struct list_head worklist;
+ struct xchk_rtrefcnt_frag *frag;
+ struct xchk_rtrefcnt_frag *n;
+ xfs_rgblock_t bno;
+ xfs_rgblock_t rbno;
+ xfs_rgblock_t next_rbno;
+ xfs_nlink_t nr;
+ xfs_nlink_t target_nr;
+
+ target_nr = refchk->refcount - refchk->seen;
+ if (target_nr == 0)
+ return;
+
+ /*
+ * There are (refchk->rc.rc_refcount - refchk->nr refcount)
+ * references we haven't found yet. Pull that many off the
+ * fragment list and figure out where the smallest rmap ends
+ * (and therefore the next rmap should start). All the rmaps
+ * we pull off should start at or before the beginning of the
+ * refcount record's range.
+ */
+ INIT_LIST_HEAD(&worklist);
+ rbno = NULLRGBLOCK;
+
+ /* Make sure the fragments actually /are/ in bno order. */
+ bno = 0;
+ list_for_each_entry(frag, &refchk->fragments, list) {
+ if (frag->rm.rm_startblock < bno)
+ goto done;
+ bno = frag->rm.rm_startblock;
+ }
+
+ /*
+ * Find all the rmaps that start at or before the refc extent,
+ * and put them on the worklist.
+ */
+ nr = 0;
+ list_for_each_entry_safe(frag, n, &refchk->fragments, list) {
+ if (frag->rm.rm_startblock > refchk->bno || nr > target_nr)
+ break;
+ bno = frag->rm.rm_startblock + frag->rm.rm_blockcount;
+ if (bno < rbno)
+ rbno = bno;
+ list_move_tail(&frag->list, &worklist);
+ nr++;
+ }
+
+ /*
+ * We should have found exactly $target_nr rmap fragments starting
+ * at or before the refcount extent.
+ */
+ if (nr != target_nr)
+ goto done;
+
+ while (!list_empty(&refchk->fragments)) {
+ /* Discard any fragments ending at rbno from the worklist. */
+ nr = 0;
+ next_rbno = NULLRGBLOCK;
+ list_for_each_entry_safe(frag, n, &worklist, list) {
+ bno = frag->rm.rm_startblock + frag->rm.rm_blockcount;
+ if (bno != rbno) {
+ if (bno < next_rbno)
+ next_rbno = bno;
+ continue;
+ }
+ list_del(&frag->list);
+ kfree(frag);
+ nr++;
+ }
+
+ /* Try to add nr rmaps starting at rbno to the worklist. */
+ list_for_each_entry_safe(frag, n, &refchk->fragments, list) {
+ bno = frag->rm.rm_startblock + frag->rm.rm_blockcount;
+ if (frag->rm.rm_startblock != rbno)
+ goto done;
+ list_move_tail(&frag->list, &worklist);
+ if (next_rbno > bno)
+ next_rbno = bno;
+ nr--;
+ if (nr == 0)
+ break;
+ }
+
+ /*
+ * If we get here and nr > 0, this means that we added fewer
+ * items to the worklist than we discarded because the fragment
+ * list ran out of items. Therefore, we cannot maintain the
+ * required refcount. Something is wrong, so we're done.
+ */
+ if (nr)
+ goto done;
+
+ rbno = next_rbno;
+ }
+
+ /*
+ * Make sure the last extent we processed ends at or beyond
+ * the end of the refcount extent.
+ */
+ if (rbno < refchk->bno + refchk->len)
+ goto done;
+
+ /* Actually record us having seen the remaining refcount. */
+ refchk->seen = refchk->refcount;
+done:
+ /* Delete fragments and work list. */
+ list_for_each_entry_safe(frag, n, &worklist, list) {
+ list_del(&frag->list);
+ kfree(frag);
+ }
+ list_for_each_entry_safe(frag, n, &refchk->fragments, list) {
+ list_del(&frag->list);
+ kfree(frag);
+ }
+}
+
+/* Use the rmap entries covering this extent to verify the refcount. */
+STATIC void
+xchk_rtrefcountbt_xref_rmap(
+ struct xfs_scrub *sc,
+ const struct xfs_refcount_irec *irec)
+{
+ struct xchk_rtrefcnt_check refchk = {
+ .sc = sc,
+ .bno = irec->rc_startblock,
+ .len = irec->rc_blockcount,
+ .refcount = irec->rc_refcount,
+ .seen = 0,
+ };
+ struct xfs_rmap_irec low;
+ struct xfs_rmap_irec high;
+ struct xchk_rtrefcnt_frag *frag;
+ struct xchk_rtrefcnt_frag *n;
+ int error;
+
+ if (!sc->sr.rmap_cur || xchk_skip_xref(sc->sm))
+ return;
+
+ /* Cross-reference with the rmapbt to confirm the refcount. */
+ memset(&low, 0, sizeof(low));
+ low.rm_startblock = irec->rc_startblock;
+ memset(&high, 0xFF, sizeof(high));
+ high.rm_startblock = irec->rc_startblock + irec->rc_blockcount - 1;
+
+ INIT_LIST_HEAD(&refchk.fragments);
+ error = xfs_rmap_query_range(sc->sr.rmap_cur, &low, &high,
+ xchk_rtrefcountbt_rmap_check, &refchk);
+ if (!xchk_should_check_xref(sc, &error, &sc->sr.rmap_cur))
+ goto out_free;
+
+ xchk_rtrefcountbt_process_rmap_fragments(&refchk);
+ if (irec->rc_refcount != refchk.seen)
+ xchk_btree_xref_set_corrupt(sc, sc->sr.rmap_cur, 0);
+
+out_free:
+ list_for_each_entry_safe(frag, n, &refchk.fragments, list) {
+ list_del(&frag->list);
+ kfree(frag);
+ }
+}
+
+/* Cross-reference with the other btrees. */
+STATIC void
+xchk_rtrefcountbt_xref(
+ struct xfs_scrub *sc,
+ const struct xfs_refcount_irec *irec)
+{
+ if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
+ return;
+
+ xchk_xref_is_used_rt_space(sc,
+ xfs_rgbno_to_rtb(sc->sr.rtg, irec->rc_startblock),
+ irec->rc_blockcount);
+ xchk_rtrefcountbt_xref_rmap(sc, irec);
+}
+
+struct xchk_rtrefcbt_records {
+ /* Previous refcount record. */
+ struct xfs_refcount_irec prev_rec;
+
+ /* Number of CoW blocks we expect. */
+ xfs_extlen_t cow_blocks;
+};
+
+static inline bool
+xchk_rtrefcount_mergeable(
+ struct xchk_rtrefcbt_records *rrc,
+ const struct xfs_refcount_irec *r2)
+{
+ const struct xfs_refcount_irec *r1 = &rrc->prev_rec;
+
+ /* Ignore if prev_rec is not yet initialized. */
+ if (r1->rc_blockcount > 0)
+ return false;
+
+ if (r1->rc_startblock + r1->rc_blockcount != r2->rc_startblock)
+ return false;
+ if (r1->rc_refcount != r2->rc_refcount)
+ return false;
+ if ((unsigned long long)r1->rc_blockcount + r2->rc_blockcount >
+ XFS_REFC_LEN_MAX)
+ return false;
+
+ return true;
+}
+
+/* Flag failures for records that could be merged. */
+STATIC void
+xchk_rtrefcountbt_check_mergeable(
+ struct xchk_btree *bs,
+ struct xchk_rtrefcbt_records *rrc,
+ const struct xfs_refcount_irec *irec)
+{
+ if (bs->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
+ return;
+
+ if (xchk_rtrefcount_mergeable(rrc, irec))
+ xchk_btree_set_corrupt(bs->sc, bs->cur, 0);
+
+ memcpy(&rrc->prev_rec, irec, sizeof(struct xfs_refcount_irec));
+}
+
+/* Scrub a rtrefcountbt record. */
+STATIC int
+xchk_rtrefcountbt_rec(
+ struct xchk_btree *bs,
+ const union xfs_btree_rec *rec)
+{
+ struct xfs_mount *mp = bs->cur->bc_mp;
+ struct xchk_rtrefcbt_records *rrc = bs->private;
+ struct xfs_refcount_irec irec;
+ u32 mod;
+
+ xfs_refcount_btrec_to_irec(rec, &irec);
+ if (xfs_rtrefcount_check_irec(to_rtg(bs->cur->bc_group), &irec) !=
+ NULL) {
+ xchk_btree_set_corrupt(bs->sc, bs->cur, 0);
+ return 0;
+ }
+
+ /* We can only share full rt extents. */
+ mod = xfs_rgbno_to_rtxoff(mp, irec.rc_startblock);
+ if (mod)
+ xchk_btree_set_corrupt(bs->sc, bs->cur, 0);
+ mod = xfs_extlen_to_rtxmod(mp, irec.rc_blockcount);
+ if (mod)
+ xchk_btree_set_corrupt(bs->sc, bs->cur, 0);
+
+ if (irec.rc_domain == XFS_REFC_DOMAIN_COW)
+ rrc->cow_blocks += irec.rc_blockcount;
+
+ xchk_rtrefcountbt_check_mergeable(bs, rrc, &irec);
+ xchk_rtrefcountbt_xref(bs->sc, &irec);
+
+ return 0;
+}
+
+/* Make sure we have as many refc blocks as the rmap says. */
+STATIC void
+xchk_refcount_xref_rmap(
+ struct xfs_scrub *sc,
+ const struct xfs_owner_info *btree_oinfo,
+ xfs_extlen_t cow_blocks)
+{
+ xfs_extlen_t refcbt_blocks = 0;
+ xfs_filblks_t blocks;
+ int error;
+
+ if (!sc->sr.rmap_cur || !sc->sa.rmap_cur || xchk_skip_xref(sc->sm))
+ return;
+
+ /* Check that we saw as many refcbt blocks as the rmap knows about. */
+ error = xfs_btree_count_blocks(sc->sr.refc_cur, &refcbt_blocks);
+ if (!xchk_btree_process_error(sc, sc->sr.refc_cur, 0, &error))
+ return;
+ error = xchk_count_rmap_ownedby_ag(sc, sc->sa.rmap_cur, btree_oinfo,
+ &blocks);
+ if (!xchk_should_check_xref(sc, &error, &sc->sa.rmap_cur))
+ return;
+ if (blocks != refcbt_blocks)
+ xchk_btree_xref_set_corrupt(sc, sc->sa.rmap_cur, 0);
+
+ /* Check that we saw as many cow blocks as the rmap knows about. */
+ error = xchk_count_rmap_ownedby_ag(sc, sc->sr.rmap_cur,
+ &XFS_RMAP_OINFO_COW, &blocks);
+ if (!xchk_should_check_xref(sc, &error, &sc->sr.rmap_cur))
+ return;
+ if (blocks != cow_blocks)
+ xchk_btree_xref_set_corrupt(sc, sc->sr.rmap_cur, 0);
+}
+
+/* Scrub the refcount btree for some AG. */
+int
+xchk_rtrefcountbt(
+ struct xfs_scrub *sc)
+{
+ struct xfs_owner_info btree_oinfo;
+ struct xchk_rtrefcbt_records rrc = {
+ .cow_blocks = 0,
+ };
+ int error;
+
+ error = xchk_metadata_inode_forks(sc);
+ if (error || (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT))
+ return error;
+
+ xfs_rmap_ino_bmbt_owner(&btree_oinfo,
+ sc->sr.rtg->rtg_inodes[XFS_RTGI_REFCOUNT]->i_ino,
+ XFS_DATA_FORK);
+ error = xchk_btree(sc, sc->sr.refc_cur, xchk_rtrefcountbt_rec,
+ &btree_oinfo, &rrc);
+ if (error || (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT))
+ return error;
+
+ xchk_refcount_xref_rmap(sc, &btree_oinfo, rrc.cow_blocks);
+
+ return 0;
+}
projects / users / hch / xfs.git / commitdiff