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-rw-r--r--fs/xfs/scrub/refcount.c620
1 files changed, 620 insertions, 0 deletions
diff --git a/fs/xfs/scrub/refcount.c b/fs/xfs/scrub/refcount.c
new file mode 100644
index 0000000000..304ea1e1bf
--- /dev/null
+++ b/fs/xfs/scrub/refcount.c
@@ -0,0 +1,620 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2017-2023 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_ag.h"
+#include "xfs_btree.h"
+#include "xfs_rmap.h"
+#include "xfs_refcount.h"
+#include "scrub/scrub.h"
+#include "scrub/common.h"
+#include "scrub/btree.h"
+#include "scrub/trace.h"
+
+/*
+ * Set us up to scrub reference count btrees.
+ */
+int
+xchk_setup_ag_refcountbt(
+ struct xfs_scrub *sc)
+{
+ if (xchk_need_intent_drain(sc))
+ xchk_fsgates_enable(sc, XCHK_FSGATES_DRAIN);
+ return xchk_setup_ag_btree(sc, false);
+}
+
+/* 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_refcnt_frag {
+ struct list_head list;
+ struct xfs_rmap_irec rm;
+};
+
+struct xchk_refcnt_check {
+ struct xfs_scrub *sc;
+ struct list_head fragments;
+
+ /* refcount extent we're examining */
+ xfs_agblock_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 refcountbt says we should have.
+ */
+STATIC int
+xchk_refcountbt_rmap_check(
+ struct xfs_btree_cur *cur,
+ const struct xfs_rmap_irec *rec,
+ void *priv)
+{
+ struct xchk_refcnt_check *refchk = priv;
+ struct xchk_refcnt_frag *frag;
+ xfs_agblock_t rm_last;
+ xfs_agblock_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_refcnt_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 refcountbt's refcount minus the
+ * number of extents that totally covered the refcountbt extent),
+ * we have a refcountbt error.
+ */
+STATIC void
+xchk_refcountbt_process_rmap_fragments(
+ struct xchk_refcnt_check *refchk)
+{
+ struct list_head worklist;
+ struct xchk_refcnt_frag *frag;
+ struct xchk_refcnt_frag *n;
+ xfs_agblock_t bno;
+ xfs_agblock_t rbno;
+ xfs_agblock_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 = NULLAGBLOCK;
+
+ /* Make sure the fragments actually /are/ in agbno 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 = NULLAGBLOCK;
+ 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_refcountbt_xref_rmap(
+ struct xfs_scrub *sc,
+ const struct xfs_refcount_irec *irec)
+{
+ struct xchk_refcnt_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_refcnt_frag *frag;
+ struct xchk_refcnt_frag *n;
+ int error;
+
+ if (!sc->sa.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->sa.rmap_cur, &low, &high,
+ &xchk_refcountbt_rmap_check, &refchk);
+ if (!xchk_should_check_xref(sc, &error, &sc->sa.rmap_cur))
+ goto out_free;
+
+ xchk_refcountbt_process_rmap_fragments(&refchk);
+ if (irec->rc_refcount != refchk.seen) {
+ trace_xchk_refcount_incorrect(sc->sa.pag, irec, refchk.seen);
+ xchk_btree_xref_set_corrupt(sc, sc->sa.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_refcountbt_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_space(sc, irec->rc_startblock, irec->rc_blockcount);
+ xchk_xref_is_not_inode_chunk(sc, irec->rc_startblock,
+ irec->rc_blockcount);
+ xchk_refcountbt_xref_rmap(sc, irec);
+}
+
+struct xchk_refcbt_records {
+ /* Previous refcount record. */
+ struct xfs_refcount_irec prev_rec;
+
+ /* The next AG block where we aren't expecting shared extents. */
+ xfs_agblock_t next_unshared_agbno;
+
+ /* Number of CoW blocks we expect. */
+ xfs_agblock_t cow_blocks;
+
+ /* Was the last record a shared or CoW staging extent? */
+ enum xfs_refc_domain prev_domain;
+};
+
+STATIC int
+xchk_refcountbt_rmap_check_gap(
+ struct xfs_btree_cur *cur,
+ const struct xfs_rmap_irec *rec,
+ void *priv)
+{
+ xfs_agblock_t *next_bno = priv;
+
+ if (*next_bno != NULLAGBLOCK && rec->rm_startblock < *next_bno)
+ return -ECANCELED;
+
+ *next_bno = rec->rm_startblock + rec->rm_blockcount;
+ return 0;
+}
+
+/*
+ * Make sure that a gap in the reference count records does not correspond to
+ * overlapping records (i.e. shared extents) in the reverse mappings.
+ */
+static inline void
+xchk_refcountbt_xref_gaps(
+ struct xfs_scrub *sc,
+ struct xchk_refcbt_records *rrc,
+ xfs_agblock_t bno)
+{
+ struct xfs_rmap_irec low;
+ struct xfs_rmap_irec high;
+ xfs_agblock_t next_bno = NULLAGBLOCK;
+ int error;
+
+ if (bno <= rrc->next_unshared_agbno || !sc->sa.rmap_cur ||
+ xchk_skip_xref(sc->sm))
+ return;
+
+ memset(&low, 0, sizeof(low));
+ low.rm_startblock = rrc->next_unshared_agbno;
+ memset(&high, 0xFF, sizeof(high));
+ high.rm_startblock = bno - 1;
+
+ error = xfs_rmap_query_range(sc->sa.rmap_cur, &low, &high,
+ xchk_refcountbt_rmap_check_gap, &next_bno);
+ if (error == -ECANCELED)
+ xchk_btree_xref_set_corrupt(sc, sc->sa.rmap_cur, 0);
+ else
+ xchk_should_check_xref(sc, &error, &sc->sa.rmap_cur);
+}
+
+static inline bool
+xchk_refcount_mergeable(
+ struct xchk_refcbt_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_domain != r2->rc_domain)
+ 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 >
+ MAXREFCEXTLEN)
+ return false;
+
+ return true;
+}
+
+/* Flag failures for records that could be merged. */
+STATIC void
+xchk_refcountbt_check_mergeable(
+ struct xchk_btree *bs,
+ struct xchk_refcbt_records *rrc,
+ const struct xfs_refcount_irec *irec)
+{
+ if (bs->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
+ return;
+
+ if (xchk_refcount_mergeable(rrc, irec))
+ xchk_btree_set_corrupt(bs->sc, bs->cur, 0);
+
+ memcpy(&rrc->prev_rec, irec, sizeof(struct xfs_refcount_irec));
+}
+
+/* Scrub a refcountbt record. */
+STATIC int
+xchk_refcountbt_rec(
+ struct xchk_btree *bs,
+ const union xfs_btree_rec *rec)
+{
+ struct xfs_refcount_irec irec;
+ struct xchk_refcbt_records *rrc = bs->private;
+
+ xfs_refcount_btrec_to_irec(rec, &irec);
+ if (xfs_refcount_check_irec(bs->cur, &irec) != NULL) {
+ xchk_btree_set_corrupt(bs->sc, bs->cur, 0);
+ return 0;
+ }
+
+ if (irec.rc_domain == XFS_REFC_DOMAIN_COW)
+ rrc->cow_blocks += irec.rc_blockcount;
+
+ /* Shared records always come before CoW records. */
+ if (irec.rc_domain == XFS_REFC_DOMAIN_SHARED &&
+ rrc->prev_domain == XFS_REFC_DOMAIN_COW)
+ xchk_btree_set_corrupt(bs->sc, bs->cur, 0);
+ rrc->prev_domain = irec.rc_domain;
+
+ xchk_refcountbt_check_mergeable(bs, rrc, &irec);
+ xchk_refcountbt_xref(bs->sc, &irec);
+
+ /*
+ * If this is a record for a shared extent, check that all blocks
+ * between the previous record and this one have at most one reverse
+ * mapping.
+ */
+ if (irec.rc_domain == XFS_REFC_DOMAIN_SHARED) {
+ xchk_refcountbt_xref_gaps(bs->sc, rrc, irec.rc_startblock);
+ rrc->next_unshared_agbno = irec.rc_startblock +
+ irec.rc_blockcount;
+ }
+
+ return 0;
+}
+
+/* Make sure we have as many refc blocks as the rmap says. */
+STATIC void
+xchk_refcount_xref_rmap(
+ struct xfs_scrub *sc,
+ xfs_filblks_t cow_blocks)
+{
+ xfs_extlen_t refcbt_blocks = 0;
+ xfs_filblks_t blocks;
+ int error;
+
+ if (!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->sa.refc_cur, &refcbt_blocks);
+ if (!xchk_btree_process_error(sc, sc->sa.refc_cur, 0, &error))
+ return;
+ error = xchk_count_rmap_ownedby_ag(sc, sc->sa.rmap_cur,
+ &XFS_RMAP_OINFO_REFC, &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->sa.rmap_cur,
+ &XFS_RMAP_OINFO_COW, &blocks);
+ if (!xchk_should_check_xref(sc, &error, &sc->sa.rmap_cur))
+ return;
+ if (blocks != cow_blocks)
+ xchk_btree_xref_set_corrupt(sc, sc->sa.rmap_cur, 0);
+}
+
+/* Scrub the refcount btree for some AG. */
+int
+xchk_refcountbt(
+ struct xfs_scrub *sc)
+{
+ struct xchk_refcbt_records rrc = {
+ .cow_blocks = 0,
+ .next_unshared_agbno = 0,
+ .prev_domain = XFS_REFC_DOMAIN_SHARED,
+ };
+ int error;
+
+ error = xchk_btree(sc, sc->sa.refc_cur, xchk_refcountbt_rec,
+ &XFS_RMAP_OINFO_REFC, &rrc);
+ if (error)
+ return error;
+
+ /*
+ * Check that all blocks between the last refcount > 1 record and the
+ * end of the AG have at most one reverse mapping.
+ */
+ xchk_refcountbt_xref_gaps(sc, &rrc, sc->mp->m_sb.sb_agblocks);
+
+ xchk_refcount_xref_rmap(sc, rrc.cow_blocks);
+
+ return 0;
+}
+
+/* xref check that a cow staging extent is marked in the refcountbt. */
+void
+xchk_xref_is_cow_staging(
+ struct xfs_scrub *sc,
+ xfs_agblock_t agbno,
+ xfs_extlen_t len)
+{
+ struct xfs_refcount_irec rc;
+ int has_refcount;
+ int error;
+
+ if (!sc->sa.refc_cur || xchk_skip_xref(sc->sm))
+ return;
+
+ /* Find the CoW staging extent. */
+ error = xfs_refcount_lookup_le(sc->sa.refc_cur, XFS_REFC_DOMAIN_COW,
+ agbno, &has_refcount);
+ if (!xchk_should_check_xref(sc, &error, &sc->sa.refc_cur))
+ return;
+ if (!has_refcount) {
+ xchk_btree_xref_set_corrupt(sc, sc->sa.refc_cur, 0);
+ return;
+ }
+
+ error = xfs_refcount_get_rec(sc->sa.refc_cur, &rc, &has_refcount);
+ if (!xchk_should_check_xref(sc, &error, &sc->sa.refc_cur))
+ return;
+ if (!has_refcount) {
+ xchk_btree_xref_set_corrupt(sc, sc->sa.refc_cur, 0);
+ return;
+ }
+
+ /* CoW lookup returned a shared extent record? */
+ if (rc.rc_domain != XFS_REFC_DOMAIN_COW)
+ xchk_btree_xref_set_corrupt(sc, sc->sa.refc_cur, 0);
+
+ /* Must be at least as long as what was passed in */
+ if (rc.rc_blockcount < len)
+ xchk_btree_xref_set_corrupt(sc, sc->sa.refc_cur, 0);
+}
+
+/*
+ * xref check that the extent is not shared. Only file data blocks
+ * can have multiple owners.
+ */
+void
+xchk_xref_is_not_shared(
+ struct xfs_scrub *sc,
+ xfs_agblock_t agbno,
+ xfs_extlen_t len)
+{
+ enum xbtree_recpacking outcome;
+ int error;
+
+ if (!sc->sa.refc_cur || xchk_skip_xref(sc->sm))
+ return;
+
+ error = xfs_refcount_has_records(sc->sa.refc_cur,
+ XFS_REFC_DOMAIN_SHARED, agbno, len, &outcome);
+ if (!xchk_should_check_xref(sc, &error, &sc->sa.refc_cur))
+ return;
+ if (outcome != XBTREE_RECPACKING_EMPTY)
+ xchk_btree_xref_set_corrupt(sc, sc->sa.refc_cur, 0);
+}
+
+/* xref check that the extent is not being used for CoW staging. */
+void
+xchk_xref_is_not_cow_staging(
+ struct xfs_scrub *sc,
+ xfs_agblock_t agbno,
+ xfs_extlen_t len)
+{
+ enum xbtree_recpacking outcome;
+ int error;
+
+ if (!sc->sa.refc_cur || xchk_skip_xref(sc->sm))
+ return;
+
+ error = xfs_refcount_has_records(sc->sa.refc_cur, XFS_REFC_DOMAIN_COW,
+ agbno, len, &outcome);
+ if (!xchk_should_check_xref(sc, &error, &sc->sa.refc_cur))
+ return;
+ if (outcome != XBTREE_RECPACKING_EMPTY)
+ xchk_btree_xref_set_corrupt(sc, sc->sa.refc_cur, 0);
+}