From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Cross reference the refcount data with the rmap data to check that the
number of rmaps for a given block match the refcount of that block, and
that CoW blocks (which are owned entirely by the refcountbt) are tracked
as well.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
fs/xfs/scrub/refcount.c | 237 +++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 235 insertions(+), 2 deletions(-)
diff --git a/fs/xfs/scrub/refcount.c b/fs/xfs/scrub/refcount.c
index f8f51e2..999820b 100644
--- a/fs/xfs/scrub/refcount.c
+++ b/fs/xfs/scrub/refcount.c
@@ -51,6 +51,165 @@ xfs_scrub_setup_ag_refcountbt(
/* Reference count btree scrubber. */
+struct xfs_scrub_refcountbt_fragment {
+ struct list_head list;
+ struct xfs_rmap_irec rm;
+};
+
+struct xfs_scrub_refcountbt_rmap_check_info {
+ struct xfs_scrub_btree *bs;
+ xfs_filblks_t cow_blocks;
+ struct xfs_refcount_irec rc;
+ struct list_head fragments;
+ xfs_nlink_t nr;
+};
+
+/*
+ * 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
+xfs_scrub_refcountbt_rmap_check(
+ struct xfs_btree_cur *cur,
+ struct xfs_rmap_irec *rec,
+ void *priv)
+{
+ struct xfs_scrub_refcountbt_rmap_check_info *rsrci = priv;
+ struct xfs_scrub_refcountbt_fragment *frag;
+ xfs_agblock_t rm_last;
+ xfs_agblock_t rc_last;
+
+ rm_last = rec->rm_startblock + rec->rm_blockcount;
+ rc_last = rsrci->rc.rc_startblock + rsrci->rc.rc_blockcount;
+ xfs_scrub_btree_xref_check_ok(rsrci->bs->sc, cur, 0,
+ rsrci->rc.rc_refcount != 1 ||
+ rec->rm_owner == XFS_RMAP_OWN_COW);
+ if (rec->rm_startblock <= rsrci->rc.rc_startblock &&
+ rm_last >= rc_last) {
+ rsrci->nr++;
+ } else {
+ frag = kmem_alloc(sizeof(struct xfs_scrub_refcountbt_fragment),
+ KM_MAYFAIL | KM_NOFS);
+ if (!frag)
+ return -ENOMEM;
+ frag->rm = *rec;
+ list_add_tail(&frag->list, &rsrci->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
+xfs_scrub_refcountbt_process_rmap_fragments(
+ struct xfs_scrub_refcountbt_rmap_check_info *rsrci)
+{
+ struct list_head worklist;
+ struct xfs_scrub_refcountbt_fragment *frag;
+ struct xfs_scrub_refcountbt_fragment *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 = rsrci->rc.rc_refcount - rsrci->nr;
+ if (target_nr == 0)
+ return;
+
+ /*
+ * There are (rsrci->rc.rc_refcount - rsrci->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;
+ nr = 1;
+ list_for_each_entry_safe(frag, n, &rsrci->fragments, list) {
+ if (frag->rm.rm_startblock > rsrci->rc.rc_startblock)
+ goto fail;
+ bno = frag->rm.rm_startblock + frag->rm.rm_blockcount;
+ if (rbno > bno)
+ rbno = bno;
+ list_del(&frag->list);
+ list_add_tail(&frag->list, &worklist);
+ if (nr == target_nr)
+ break;
+ nr++;
+ }
+
+ if (nr != target_nr)
+ goto fail;
+
+ while (!list_empty(&rsrci->fragments)) {
+ /* Discard any fragments ending at rbno. */
+ 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 (next_rbno > bno)
+ next_rbno = bno;
+ continue;
+ }
+ list_del(&frag->list);
+ kmem_free(frag);
+ nr++;
+ }
+
+ /* Empty list? We're done. */
+ if (list_empty(&rsrci->fragments))
+ break;
+
+ /* Try to add nr rmaps starting at rbno to the worklist. */
+ list_for_each_entry_safe(frag, n, &rsrci->fragments, list) {
+ bno = frag->rm.rm_startblock + frag->rm.rm_blockcount;
+ if (frag->rm.rm_startblock != rbno)
+ goto fail;
+ list_del(&frag->list);
+ list_add_tail(&frag->list, &worklist);
+ if (next_rbno > bno)
+ next_rbno = bno;
+ nr--;
+ if (nr == 0)
+ break;
+ }
+
+ rbno = next_rbno;
+ }
+
+ /*
+ * Make sure the last extent we processed ends at or beyond
+ * the end of the refcount extent.
+ */
+ if (rbno < rsrci->rc.rc_startblock + rsrci->rc.rc_blockcount)
+ goto fail;
+
+ rsrci->nr = rsrci->rc.rc_refcount;
+fail:
+ /* Delete fragments and work list. */
+ list_for_each_entry_safe(frag, n, &worklist, list) {
+ list_del(&frag->list);
+ kmem_free(frag);
+ }
+ list_for_each_entry_safe(frag, n, &rsrci->fragments, list) {
+ list_del(&frag->list);
+ kmem_free(frag);
+ }
+}
+
/* Scrub a refcountbt record. */
STATIC int
xfs_scrub_refcountbt_helper(
@@ -61,6 +220,11 @@ xfs_scrub_refcountbt_helper(
struct xfs_agf *agf;
struct xfs_scrub_ag *psa;
struct xfs_refcount_irec irec;
+ struct xfs_rmap_irec low;
+ struct xfs_rmap_irec high;
+ struct xfs_scrub_refcountbt_rmap_check_info *rsrci = bs->private;
+ struct xfs_scrub_refcountbt_fragment *frag;
+ struct xfs_scrub_refcountbt_fragment *n;
unsigned long long rec_end;
xfs_agblock_t eoag;
bool has_cowflag;
@@ -75,6 +239,8 @@ xfs_scrub_refcountbt_helper(
eoag = be32_to_cpu(agf->agf_length);
has_cowflag = !!(irec.rc_startblock & XFS_REFC_COW_START);
+ if (has_cowflag)
+ rsrci->cow_blocks += irec.rc_blockcount;
xfs_scrub_btree_check_ok(bs->sc, bs->cur, 0,
(irec.rc_refcount == 1 && has_cowflag) ||
(irec.rc_refcount != 1 && !has_cowflag));
@@ -123,17 +289,84 @@ xfs_scrub_refcountbt_helper(
!has_inodes);
}
+ /* Cross-reference with the rmapbt to confirm the refcount. */
+ if (psa->rmap_cur) {
+ 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;
+
+ rsrci->bs = bs;
+ rsrci->nr = 0;
+ rsrci->rc = irec;
+ ASSERT(list_empty(&rsrci->fragments));
+ error = xfs_rmap_query_range(psa->rmap_cur, &low, &high,
+ &xfs_scrub_refcountbt_rmap_check, rsrci);
+ if (xfs_scrub_should_xref(bs->sc, &error, &psa->rmap_cur)) {
+ xfs_scrub_refcountbt_process_rmap_fragments(rsrci);
+ xfs_scrub_btree_xref_check_ok(bs->sc, psa->rmap_cur, 0,
+ irec.rc_refcount == rsrci->nr);
+ }
+
+ list_for_each_entry_safe(frag, n, &rsrci->fragments, list) {
+ list_del(&frag->list);
+ kmem_free(frag);
+ }
+ }
+
return error;
}
+/* Make sure we have as many refc blocks as the rmap says. */
+STATIC void
+xfs_scrub_refcount_xref_rmap(
+ struct xfs_scrub_context *sc,
+ struct xfs_owner_info *oinfo,
+ xfs_filblks_t cow_blocks)
+{
+ xfs_extlen_t refcbt_blocks = 0;
+ xfs_filblks_t blocks;
+ int error;
+
+ /* 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 (!xfs_scrub_btree_op_ok(sc, sc->sa.refc_cur, 0, &error))
+ return;
+ error = xfs_scrub_count_rmap_ownedby_ag(sc, sc->sa.rmap_cur, oinfo,
+ &blocks);
+ if (xfs_scrub_should_xref(sc, &error, &sc->sa.rmap_cur))
+ xfs_scrub_btree_xref_check_ok(sc, sc->sa.rmap_cur, 0,
+ blocks == refcbt_blocks);
+
+ /* Check that we saw as many cow blocks as the rmap knows about. */
+ xfs_rmap_ag_owner(oinfo, XFS_RMAP_OWN_COW);
+ error = xfs_scrub_count_rmap_ownedby_ag(sc, sc->sa.rmap_cur, oinfo,
+ &blocks);
+ if (xfs_scrub_should_xref(sc, &error, &sc->sa.rmap_cur))
+ xfs_scrub_btree_xref_check_ok(sc, sc->sa.rmap_cur, 0,
+ blocks == cow_blocks);
+}
+
/* Scrub the refcount btree for some AG. */
int
xfs_scrub_refcountbt(
struct xfs_scrub_context *sc)
{
struct xfs_owner_info oinfo;
+ struct xfs_scrub_refcountbt_rmap_check_info rsrci;
+ int error;
+ INIT_LIST_HEAD(&rsrci.fragments);
+ rsrci.cow_blocks = 0;
xfs_rmap_ag_owner(&oinfo, XFS_RMAP_OWN_REFC);
- return xfs_scrub_btree(sc, sc->sa.refc_cur, xfs_scrub_refcountbt_helper,
- &oinfo, NULL);
+ error = xfs_scrub_btree(sc, sc->sa.refc_cur,
+ xfs_scrub_refcountbt_helper, &oinfo, &rsrci);
+ if (error)
+ return error;
+
+ if (sc->sa.rmap_cur)
+ xfs_scrub_refcount_xref_rmap(sc, &oinfo, rsrci.cow_blocks);
+
+ return error;
}
--
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