[PATCHSET v23.1 0/4] xfs: strengthen rmapbt scrubbing

[PATCHSET v23.1 0/4] xfs: strengthen rmapbt scrubbing

[Darrick J. Wong]

Hi all,

This series strengthens space allocation record cross referencing by
using our improved xbitmaps to compute the difference between space used
according to the rmap records and the primary metadata, and reports
cross-referencing errors for any discrepancies.

If you're going to start using this mess, you probably ought to just
pull from my git trees, which are linked below.

This is an extraordinary way to destroy everything.  Enjoy!
Comments and questions are, as always, welcome.

--D

kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=scrub-strengthen-rmap-checking
---
 fs/xfs/Makefile       |    2 
 fs/xfs/scrub/bitmap.c |   22 +++
 fs/xfs/scrub/bitmap.h |    1 
 fs/xfs/scrub/rmap.c   |  313 +++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 336 insertions(+), 2 deletions(-)

[PATCH 1/4] xfs: cross-reference rmap records with ag btrees

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Strengthen the rmap btree record checker a little more by comparing
OWN_FS and OWN_LOG reverse mappings against the AG headers and internal
logs, respectively.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/Makefile       |    2 -
 fs/xfs/scrub/bitmap.c |   22 +++++++
 fs/xfs/scrub/bitmap.h |    1 
 fs/xfs/scrub/rmap.c   |  160 +++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 183 insertions(+), 2 deletions(-)


diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
index 03135a1c31b6..7b54cdbe8c9c 100644
--- a/fs/xfs/Makefile
+++ b/fs/xfs/Makefile
@@ -145,6 +145,7 @@ xfs-y				+= $(addprefix scrub/, \
 				   agheader.o \
 				   alloc.o \
 				   attr.o \
+				   bitmap.o \
 				   bmap.o \
 				   btree.o \
 				   common.o \
@@ -168,7 +169,6 @@ xfs-$(CONFIG_XFS_QUOTA)		+= scrub/quota.o
 ifeq ($(CONFIG_XFS_ONLINE_REPAIR),y)
 xfs-y				+= $(addprefix scrub/, \
 				   agheader_repair.o \
-				   bitmap.o \
 				   repair.o \
 				   )
 endif
diff --git a/fs/xfs/scrub/bitmap.c b/fs/xfs/scrub/bitmap.c
index 1b04d2ce020a..14caff0a28ce 100644
--- a/fs/xfs/scrub/bitmap.c
+++ b/fs/xfs/scrub/bitmap.c
@@ -396,3 +396,25 @@ xbitmap_empty(
 {
 	return bitmap->xb_root.rb_root.rb_node == NULL;
 }
+
+/* Is the start of the range set or clear?  And for how long? */
+bool
+xbitmap_test(
+	struct xbitmap		*bitmap,
+	uint64_t		start,
+	uint64_t		*len)
+{
+	struct xbitmap_node	*bn;
+	uint64_t		last = start + *len - 1;
+
+	bn = xbitmap_tree_iter_first(&bitmap->xb_root, start, last);
+	if (!bn)
+		return false;
+	if (bn->bn_start <= start) {
+		if (bn->bn_last < last)
+			*len = bn->bn_last - start + 1;
+		return true;
+	}
+	*len = bn->bn_start - start;
+	return false;
+}
diff --git a/fs/xfs/scrub/bitmap.h b/fs/xfs/scrub/bitmap.h
index 7afd64a318d1..2da3d6b87565 100644
--- a/fs/xfs/scrub/bitmap.h
+++ b/fs/xfs/scrub/bitmap.h
@@ -38,5 +38,6 @@ int xbitmap_walk_bits(struct xbitmap *bitmap, xbitmap_walk_bits_fn fn,
 		void *priv);
 
 bool xbitmap_empty(struct xbitmap *bitmap);
+bool xbitmap_test(struct xbitmap *bitmap, uint64_t start, uint64_t *len);
 
 #endif	/* __XFS_SCRUB_BITMAP_H__ */
diff --git a/fs/xfs/scrub/rmap.c b/fs/xfs/scrub/rmap.c
index 76ac2279e37d..8205086aac49 100644
--- a/fs/xfs/scrub/rmap.c
+++ b/fs/xfs/scrub/rmap.c
@@ -12,10 +12,12 @@
 #include "xfs_btree.h"
 #include "xfs_rmap.h"
 #include "xfs_refcount.h"
+#include "xfs_ag.h"
+#include "xfs_bit.h"
 #include "scrub/scrub.h"
 #include "scrub/common.h"
 #include "scrub/btree.h"
-#include "xfs_ag.h"
+#include "scrub/bitmap.h"
 
 /*
  * Set us up to scrub reverse mapping btrees.
@@ -45,6 +47,13 @@ struct xchk_rmap {
 	 * that could be one.
 	 */
 	struct xfs_rmap_irec	prev_rec;
+
+	/* Bitmaps containing all blocks for each type of AG metadata. */
+	struct xbitmap		fs_owned;
+	struct xbitmap		log_owned;
+
+	/* Did we complete the AG space metadata bitmaps? */
+	bool			bitmaps_complete;
 };
 
 /* Cross-reference a rmap against the refcount btree. */
@@ -197,6 +206,68 @@ xchk_rmapbt_check_mergeable(
 	memcpy(&cr->prev_rec, irec, sizeof(struct xfs_rmap_irec));
 }
 
+/* Compare an rmap for AG metadata against the metadata walk. */
+STATIC int
+xchk_rmapbt_mark_bitmap(
+	struct xchk_btree		*bs,
+	struct xchk_rmap		*cr,
+	const struct xfs_rmap_irec	*irec)
+{
+	struct xfs_scrub		*sc = bs->sc;
+	struct xbitmap			*bmp = NULL;
+	uint64_t			fsbcount = irec->rm_blockcount;
+
+	/*
+	 * Skip corrupt records.  It is essential that we detect records in the
+	 * btree that cannot overlap but do, flag those as CORRUPT, and skip
+	 * the bitmap comparison to avoid generating false XCORRUPT reports.
+	 */
+	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
+		return 0;
+
+	/*
+	 * If the AG metadata walk didn't complete, there's no point in
+	 * comparing against partial results.
+	 */
+	if (!cr->bitmaps_complete)
+		return 0;
+
+	switch (irec->rm_owner) {
+	case XFS_RMAP_OWN_FS:
+		bmp = &cr->fs_owned;
+		break;
+	case XFS_RMAP_OWN_LOG:
+		bmp = &cr->log_owned;
+		break;
+	}
+
+	if (!bmp)
+		return 0;
+
+	if (xbitmap_test(bmp, irec->rm_startblock, &fsbcount)) {
+		/*
+		 * The start of this reverse mapping corresponds to a set
+		 * region in the bitmap.  If the mapping covers more area than
+		 * the set region, then it covers space that wasn't found by
+		 * the AG metadata walk.
+		 */
+		if (fsbcount < irec->rm_blockcount)
+			xchk_btree_xref_set_corrupt(bs->sc,
+					bs->sc->sa.rmap_cur, 0);
+	} else {
+		/*
+		 * The start of this reverse mapping does not correspond to a
+		 * completely set region in the bitmap.  The region wasn't
+		 * fully set by walking the AG metadata, so this is a
+		 * cross-referencing corruption.
+		 */
+		xchk_btree_xref_set_corrupt(bs->sc, bs->sc->sa.rmap_cur, 0);
+	}
+
+	/* Unset the region so that we can detect missing rmap records. */
+	return xbitmap_clear(bmp, irec->rm_startblock, irec->rm_blockcount);
+}
+
 /* Scrub an rmapbt record. */
 STATIC int
 xchk_rmapbt_rec(
@@ -272,10 +343,82 @@ xchk_rmapbt_rec(
 	xchk_rmapbt_check_mergeable(bs, cr, &irec);
 	xchk_rmapbt_check_overlapping(bs, cr, &irec);
 	xchk_rmapbt_xref(bs->sc, &irec);
+
+	error = xchk_rmapbt_mark_bitmap(bs, cr, &irec);
 out:
 	return error;
 }
 
+/*
+ * Set up bitmaps mapping all the AG metadata to compare with the rmapbt
+ * records.
+ */
+STATIC int
+xchk_rmapbt_walk_ag_metadata(
+	struct xfs_scrub	*sc,
+	struct xchk_rmap	*cr)
+{
+	struct xfs_mount	*mp = sc->mp;
+	int			error;
+
+	/* OWN_FS: AG headers */
+	error = xbitmap_set(&cr->fs_owned, XFS_SB_BLOCK(mp),
+			XFS_AGFL_BLOCK(mp) - XFS_SB_BLOCK(mp) + 1);
+	if (error)
+		goto out;
+
+	/* OWN_LOG: Internal log */
+	if (xfs_ag_contains_log(mp, sc->sa.pag->pag_agno)) {
+		error = xbitmap_set(&cr->log_owned,
+				XFS_FSB_TO_AGBNO(mp, mp->m_sb.sb_logstart),
+				mp->m_sb.sb_logblocks);
+		if (error)
+			goto out;
+	}
+
+out:
+	/*
+	 * If there's an error, set XFAIL and disable the bitmap
+	 * cross-referencing checks, but proceed with the scrub anyway.
+	 */
+	if (error)
+		xchk_btree_xref_process_error(sc, sc->sa.rmap_cur,
+				sc->sa.rmap_cur->bc_nlevels - 1, &error);
+	else
+		cr->bitmaps_complete = true;
+	return 0;
+}
+
+/*
+ * Check for set regions in the bitmaps; if there are any, the rmap records do
+ * not describe all the AG metadata.
+ */
+STATIC void
+xchk_rmapbt_check_bitmaps(
+	struct xfs_scrub	*sc,
+	struct xchk_rmap	*cr)
+{
+	struct xfs_btree_cur	*cur = sc->sa.rmap_cur;
+	unsigned int		level;
+
+	if (sc->sm->sm_flags & (XFS_SCRUB_OFLAG_CORRUPT |
+				XFS_SCRUB_OFLAG_XFAIL))
+		return;
+	if (!cur)
+		return;
+	level = cur->bc_nlevels - 1;
+
+	/*
+	 * Any bitmap with bits still set indicates that the reverse mapping
+	 * doesn't cover the entire primary structure.
+	 */
+	if (xbitmap_hweight(&cr->fs_owned) != 0)
+		xchk_btree_xref_set_corrupt(sc, cur, level);
+
+	if (xbitmap_hweight(&cr->log_owned) != 0)
+		xchk_btree_xref_set_corrupt(sc, cur, level);
+}
+
 /* Scrub the rmap btree for some AG. */
 int
 xchk_rmapbt(
@@ -288,8 +431,23 @@ xchk_rmapbt(
 	if (!cr)
 		return -ENOMEM;
 
+	xbitmap_init(&cr->fs_owned);
+	xbitmap_init(&cr->log_owned);
+
+	error = xchk_rmapbt_walk_ag_metadata(sc, cr);
+	if (error)
+		goto out;
+
 	error = xchk_btree(sc, sc->sa.rmap_cur, xchk_rmapbt_rec,
 			&XFS_RMAP_OINFO_AG, cr);
+	if (error)
+		goto out;
+
+	xchk_rmapbt_check_bitmaps(sc, cr);
+
+out:
+	xbitmap_destroy(&cr->log_owned);
+	xbitmap_destroy(&cr->fs_owned);
 	kfree(cr);
 	return error;
 }

[PATCH 3/4] xfs: cross-reference rmap records with inode btrees

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Strengthen the rmap btree record checker a little more by comparing
OWN_INOBT reverse mappings against the inode btrees.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/scrub/rmap.c |   38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)


diff --git a/fs/xfs/scrub/rmap.c b/fs/xfs/scrub/rmap.c
index 20a6905c2f0d..fcda958ce1af 100644
--- a/fs/xfs/scrub/rmap.c
+++ b/fs/xfs/scrub/rmap.c
@@ -18,6 +18,7 @@
 #include "xfs_bit.h"
 #include "xfs_alloc.h"
 #include "xfs_alloc_btree.h"
+#include "xfs_ialloc_btree.h"
 #include "scrub/scrub.h"
 #include "scrub/common.h"
 #include "scrub/btree.h"
@@ -56,6 +57,7 @@ struct xchk_rmap {
 	struct xbitmap		fs_owned;
 	struct xbitmap		log_owned;
 	struct xbitmap		ag_owned;
+	struct xbitmap		inobt_owned;
 
 	/* Did we complete the AG space metadata bitmaps? */
 	bool			bitmaps_complete;
@@ -247,6 +249,9 @@ xchk_rmapbt_mark_bitmap(
 	case XFS_RMAP_OWN_AG:
 		bmp = &cr->ag_owned;
 		break;
+	case XFS_RMAP_OWN_INOBT:
+		bmp = &cr->inobt_owned;
+		break;
 	}
 
 	if (!bmp)
@@ -461,6 +466,34 @@ xchk_rmapbt_walk_ag_metadata(
 	error = xfs_agfl_walk(sc->mp, agf, agfl_bp, xchk_rmapbt_walk_agfl,
 			&cr->ag_owned);
 	xfs_trans_brelse(sc->tp, agfl_bp);
+	if (error)
+		goto out;
+
+	/* OWN_INOBT: inobt, finobt */
+	cur = sc->sa.ino_cur;
+	if (!cur)
+		cur = xfs_inobt_init_cursor(sc->mp, sc->tp, sc->sa.agi_bp,
+				sc->sa.pag, XFS_BTNUM_INO);
+	error = xfs_btree_visit_blocks(cur, xchk_rmapbt_visit_btblock,
+			XFS_BTREE_VISIT_ALL, &cr->inobt_owned);
+	if (cur != sc->sa.ino_cur)
+		xfs_btree_del_cursor(cur, error);
+	if (error)
+		goto out;
+
+	if (xfs_has_finobt(sc->mp)) {
+		cur = sc->sa.fino_cur;
+		if (!cur)
+			cur = xfs_inobt_init_cursor(sc->mp, sc->tp,
+					sc->sa.agi_bp, sc->sa.pag,
+					XFS_BTNUM_FINO);
+		error = xfs_btree_visit_blocks(cur, xchk_rmapbt_visit_btblock,
+				XFS_BTREE_VISIT_ALL, &cr->inobt_owned);
+		if (cur != sc->sa.fino_cur)
+			xfs_btree_del_cursor(cur, error);
+		if (error)
+			goto out;
+	}
 
 out:
 	/*
@@ -506,6 +539,9 @@ xchk_rmapbt_check_bitmaps(
 
 	if (xbitmap_hweight(&cr->ag_owned) != 0)
 		xchk_btree_xref_set_corrupt(sc, cur, level);
+
+	if (xbitmap_hweight(&cr->inobt_owned) != 0)
+		xchk_btree_xref_set_corrupt(sc, cur, level);
 }
 
 /* Scrub the rmap btree for some AG. */
@@ -523,6 +559,7 @@ xchk_rmapbt(
 	xbitmap_init(&cr->fs_owned);
 	xbitmap_init(&cr->log_owned);
 	xbitmap_init(&cr->ag_owned);
+	xbitmap_init(&cr->inobt_owned);
 
 	error = xchk_rmapbt_walk_ag_metadata(sc, cr);
 	if (error)
@@ -536,6 +573,7 @@ xchk_rmapbt(
 	xchk_rmapbt_check_bitmaps(sc, cr);
 
 out:
+	xbitmap_destroy(&cr->inobt_owned);
 	xbitmap_destroy(&cr->ag_owned);
 	xbitmap_destroy(&cr->log_owned);
 	xbitmap_destroy(&cr->fs_owned);

[PATCH 2/4] xfs: cross-reference rmap records with free space btrees

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Strengthen the rmap btree record checker a little more by comparing
OWN_AG reverse mappings against the free space btrees, the rmap btree,
and the AGFL.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/scrub/rmap.c |   91 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 91 insertions(+)


diff --git a/fs/xfs/scrub/rmap.c b/fs/xfs/scrub/rmap.c
index 8205086aac49..20a6905c2f0d 100644
--- a/fs/xfs/scrub/rmap.c
+++ b/fs/xfs/scrub/rmap.c
@@ -7,13 +7,17 @@
 #include "xfs_fs.h"
 #include "xfs_shared.h"
 #include "xfs_format.h"
+#include "xfs_log_format.h"
 #include "xfs_trans_resv.h"
 #include "xfs_mount.h"
+#include "xfs_trans.h"
 #include "xfs_btree.h"
 #include "xfs_rmap.h"
 #include "xfs_refcount.h"
 #include "xfs_ag.h"
 #include "xfs_bit.h"
+#include "xfs_alloc.h"
+#include "xfs_alloc_btree.h"
 #include "scrub/scrub.h"
 #include "scrub/common.h"
 #include "scrub/btree.h"
@@ -51,6 +55,7 @@ struct xchk_rmap {
 	/* Bitmaps containing all blocks for each type of AG metadata. */
 	struct xbitmap		fs_owned;
 	struct xbitmap		log_owned;
+	struct xbitmap		ag_owned;
 
 	/* Did we complete the AG space metadata bitmaps? */
 	bool			bitmaps_complete;
@@ -239,6 +244,9 @@ xchk_rmapbt_mark_bitmap(
 	case XFS_RMAP_OWN_LOG:
 		bmp = &cr->log_owned;
 		break;
+	case XFS_RMAP_OWN_AG:
+		bmp = &cr->ag_owned;
+		break;
 	}
 
 	if (!bmp)
@@ -349,9 +357,47 @@ xchk_rmapbt_rec(
 	return error;
 }
 
+/* Add a btree block to the rmap list. */
+STATIC int
+xchk_rmapbt_visit_btblock(
+	struct xfs_btree_cur	*cur,
+	int			level,
+	void			*priv)
+{
+	struct xbitmap		*bitmap = priv;
+	struct xfs_buf		*bp;
+	xfs_fsblock_t		fsbno;
+	xfs_agblock_t		agbno;
+
+	xfs_btree_get_block(cur, level, &bp);
+	if (!bp)
+		return 0;
+
+	fsbno = XFS_DADDR_TO_FSB(cur->bc_mp, xfs_buf_daddr(bp));
+	agbno = XFS_FSB_TO_AGBNO(cur->bc_mp, fsbno);
+	return xbitmap_set(bitmap, agbno, 1);
+}
+
+/* Add an AGFL block to the rmap list. */
+STATIC int
+xchk_rmapbt_walk_agfl(
+	struct xfs_mount	*mp,
+	xfs_agblock_t		bno,
+	void			*priv)
+{
+	struct xbitmap		*bitmap = priv;
+
+	return xbitmap_set(bitmap, bno, 1);
+}
+
 /*
  * Set up bitmaps mapping all the AG metadata to compare with the rmapbt
  * records.
+ *
+ * Grab our own btree cursors here if the scrub setup function didn't give us a
+ * btree cursor due to reports of poor health.  We need to find out if the
+ * rmapbt disagrees with primary metadata btrees to tag the rmapbt as being
+ * XCORRUPT.
  */
 STATIC int
 xchk_rmapbt_walk_ag_metadata(
@@ -359,6 +405,9 @@ xchk_rmapbt_walk_ag_metadata(
 	struct xchk_rmap	*cr)
 {
 	struct xfs_mount	*mp = sc->mp;
+	struct xfs_buf		*agfl_bp;
+	struct xfs_agf		*agf = sc->sa.agf_bp->b_addr;
+	struct xfs_btree_cur	*cur;
 	int			error;
 
 	/* OWN_FS: AG headers */
@@ -376,6 +425,43 @@ xchk_rmapbt_walk_ag_metadata(
 			goto out;
 	}
 
+	/* OWN_AG: bnobt, cntbt, rmapbt, and AGFL */
+	cur = sc->sa.bno_cur;
+	if (!cur)
+		cur = xfs_allocbt_init_cursor(sc->mp, sc->tp, sc->sa.agf_bp,
+				sc->sa.pag, XFS_BTNUM_BNO);
+	error = xfs_btree_visit_blocks(cur, xchk_rmapbt_visit_btblock,
+			XFS_BTREE_VISIT_ALL, &cr->ag_owned);
+	if (cur != sc->sa.bno_cur)
+		xfs_btree_del_cursor(cur, error);
+	if (error)
+		goto out;
+
+	cur = sc->sa.cnt_cur;
+	if (!cur)
+		cur = xfs_allocbt_init_cursor(sc->mp, sc->tp, sc->sa.agf_bp,
+				sc->sa.pag, XFS_BTNUM_CNT);
+	error = xfs_btree_visit_blocks(cur, xchk_rmapbt_visit_btblock,
+			XFS_BTREE_VISIT_ALL, &cr->ag_owned);
+	if (cur != sc->sa.cnt_cur)
+		xfs_btree_del_cursor(cur, error);
+	if (error)
+		goto out;
+
+	error = xfs_btree_visit_blocks(sc->sa.rmap_cur,
+			xchk_rmapbt_visit_btblock, XFS_BTREE_VISIT_ALL,
+			&cr->ag_owned);
+	if (error)
+		goto out;
+
+	error = xfs_alloc_read_agfl(sc->sa.pag, sc->tp, &agfl_bp);
+	if (error)
+		goto out;
+
+	error = xfs_agfl_walk(sc->mp, agf, agfl_bp, xchk_rmapbt_walk_agfl,
+			&cr->ag_owned);
+	xfs_trans_brelse(sc->tp, agfl_bp);
+
 out:
 	/*
 	 * If there's an error, set XFAIL and disable the bitmap
@@ -417,6 +503,9 @@ xchk_rmapbt_check_bitmaps(
 
 	if (xbitmap_hweight(&cr->log_owned) != 0)
 		xchk_btree_xref_set_corrupt(sc, cur, level);
+
+	if (xbitmap_hweight(&cr->ag_owned) != 0)
+		xchk_btree_xref_set_corrupt(sc, cur, level);
 }
 
 /* Scrub the rmap btree for some AG. */
@@ -433,6 +522,7 @@ xchk_rmapbt(
 
 	xbitmap_init(&cr->fs_owned);
 	xbitmap_init(&cr->log_owned);
+	xbitmap_init(&cr->ag_owned);
 
 	error = xchk_rmapbt_walk_ag_metadata(sc, cr);
 	if (error)
@@ -446,6 +536,7 @@ xchk_rmapbt(
 	xchk_rmapbt_check_bitmaps(sc, cr);
 
 out:
+	xbitmap_destroy(&cr->ag_owned);
 	xbitmap_destroy(&cr->log_owned);
 	xbitmap_destroy(&cr->fs_owned);
 	kfree(cr);

[PATCH 4/4] xfs: cross-reference rmap records with refcount btrees

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Strengthen the rmap btree record checker a little more by comparing
OWN_REFCBT reverse mappings against the refcount btrees.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/scrub/rmap.c |   24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)


diff --git a/fs/xfs/scrub/rmap.c b/fs/xfs/scrub/rmap.c
index fcda958ce1af..c63db6595e5d 100644
--- a/fs/xfs/scrub/rmap.c
+++ b/fs/xfs/scrub/rmap.c
@@ -19,6 +19,7 @@
 #include "xfs_alloc.h"
 #include "xfs_alloc_btree.h"
 #include "xfs_ialloc_btree.h"
+#include "xfs_refcount_btree.h"
 #include "scrub/scrub.h"
 #include "scrub/common.h"
 #include "scrub/btree.h"
@@ -58,6 +59,7 @@ struct xchk_rmap {
 	struct xbitmap		log_owned;
 	struct xbitmap		ag_owned;
 	struct xbitmap		inobt_owned;
+	struct xbitmap		refcbt_owned;
 
 	/* Did we complete the AG space metadata bitmaps? */
 	bool			bitmaps_complete;
@@ -252,6 +254,9 @@ xchk_rmapbt_mark_bitmap(
 	case XFS_RMAP_OWN_INOBT:
 		bmp = &cr->inobt_owned;
 		break;
+	case XFS_RMAP_OWN_REFC:
+		bmp = &cr->refcbt_owned;
+		break;
 	}
 
 	if (!bmp)
@@ -495,6 +500,20 @@ xchk_rmapbt_walk_ag_metadata(
 			goto out;
 	}
 
+	/* OWN_REFC: refcountbt */
+	if (xfs_has_reflink(sc->mp)) {
+		cur = sc->sa.refc_cur;
+		if (!cur)
+			cur = xfs_refcountbt_init_cursor(sc->mp, sc->tp,
+					sc->sa.agf_bp, sc->sa.pag);
+		error = xfs_btree_visit_blocks(cur, xchk_rmapbt_visit_btblock,
+				XFS_BTREE_VISIT_ALL, &cr->refcbt_owned);
+		if (cur != sc->sa.refc_cur)
+			xfs_btree_del_cursor(cur, error);
+		if (error)
+			goto out;
+	}
+
 out:
 	/*
 	 * If there's an error, set XFAIL and disable the bitmap
@@ -542,6 +561,9 @@ xchk_rmapbt_check_bitmaps(
 
 	if (xbitmap_hweight(&cr->inobt_owned) != 0)
 		xchk_btree_xref_set_corrupt(sc, cur, level);
+
+	if (xbitmap_hweight(&cr->refcbt_owned) != 0)
+		xchk_btree_xref_set_corrupt(sc, cur, level);
 }
 
 /* Scrub the rmap btree for some AG. */
@@ -560,6 +582,7 @@ xchk_rmapbt(
 	xbitmap_init(&cr->log_owned);
 	xbitmap_init(&cr->ag_owned);
 	xbitmap_init(&cr->inobt_owned);
+	xbitmap_init(&cr->refcbt_owned);
 
 	error = xchk_rmapbt_walk_ag_metadata(sc, cr);
 	if (error)
@@ -573,6 +596,7 @@ xchk_rmapbt(
 	xchk_rmapbt_check_bitmaps(sc, cr);
 
 out:
+	xbitmap_destroy(&cr->refcbt_owned);
 	xbitmap_destroy(&cr->inobt_owned);
 	xbitmap_destroy(&cr->ag_owned);
 	xbitmap_destroy(&cr->log_owned);