Merge tag 'realtime-reflink_2024-12-23' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into for-next

xfs: reflink on the realtime device [v6.2 05/14]

This patchset enables use of the file data block sharing feature (i.e.
reflink) on the realtime device.  It follows the same basic sequence as
the realtime rmap series -- first a few cleanups; then  introduction of
the new btree format and inode fork format.  Next comes enabling CoW and
remapping for the rt device; new scrub, repair, and health reporting
code; and at the end we implement some code to lengthen write requests
so that rt extents are always CoWed fully.

This has been running on the djcloud for months with no problems.  Enjoy!

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>

74 files changed, 4328 insertions, 350 deletions

diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
index 338e10f81b7b..7afa51e41427 100644
--- a/fs/xfs/Makefile
+++ b/fs/xfs/Makefile
@@ -51,6 +51,7 @@ xfs-y				+= $(addprefix libxfs/, \
 				   xfs_rmap_btree.o \
 				   xfs_refcount.o \
 				   xfs_refcount_btree.o \
+				   xfs_rtrefcount_btree.o \
 				   xfs_rtrmap_btree.o \
 				   xfs_sb.o \
 				   xfs_symlink_remote.o \
@@ -194,6 +195,7 @@ xfs-$(CONFIG_XFS_ONLINE_SCRUB_STATS) += scrub/stats.o
 xfs-$(CONFIG_XFS_RT)		+= $(addprefix scrub/, \
 				   rgsuper.o \
 				   rtbitmap.o \
+				   rtrefcount.o \
 				   rtrmap.o \
 				   rtsummary.o \
 				   )
@@ -234,6 +236,7 @@ xfs-y				+= $(addprefix scrub/, \
 
 xfs-$(CONFIG_XFS_RT)		+= $(addprefix scrub/, \
 				   rtbitmap_repair.o \
+				   rtrefcount_repair.o \
 				   rtrmap_repair.o \
 				   rtsummary_repair.o \
 				   )
diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 02323936cc9b..40ad22fb808b 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -4564,8 +4564,9 @@ xfs_bmapi_write(
 			 * the refcount btree for orphan recovery.
 			 */
 			if (whichfork == XFS_COW_FORK)
-				xfs_refcount_alloc_cow_extent(tp, bma.blkno,
-						bma.length);
+				xfs_refcount_alloc_cow_extent(tp,
+						XFS_IS_REALTIME_INODE(ip),
+						bma.blkno, bma.length);
 		}
 
 		/* Deal with the allocated space we found.  */
@@ -4740,7 +4741,8 @@ xfs_bmapi_convert_one_delalloc(
 		*seq = READ_ONCE(ifp->if_seq);
 
 	if (whichfork == XFS_COW_FORK)
-		xfs_refcount_alloc_cow_extent(tp, bma.blkno, bma.length);
+		xfs_refcount_alloc_cow_extent(tp, XFS_IS_REALTIME_INODE(ip),
+				bma.blkno, bma.length);
 
 	error = xfs_bmap_btree_to_extents(tp, ip, bma.cur, &bma.logflags,
 			whichfork);
@@ -5388,7 +5390,7 @@ xfs_bmap_del_extent_real(
 		bool	isrt = xfs_ifork_is_realtime(ip, whichfork);
 
 		if (xfs_is_reflink_inode(ip) && whichfork == XFS_DATA_FORK) {
-			xfs_refcount_decrease_extent(tp, del);
+			xfs_refcount_decrease_extent(tp, isrt, del);
 		} else if (isrt && !xfs_has_rtgroups(mp)) {
 			error = xfs_bmap_free_rtblocks(tp, del);
 		} else {
@@ -6498,9 +6500,8 @@ xfs_get_extsz_hint(
 	 * No point in aligning allocations if we need to COW to actually
 	 * write to them.
 	 */
-	if (xfs_is_always_cow_inode(ip))
-		return 0;
-	if ((ip->i_diflags & XFS_DIFLAG_EXTSIZE) && ip->i_extsize)
+	if (!xfs_is_always_cow_inode(ip) &&
+	    (ip->i_diflags & XFS_DIFLAG_EXTSIZE) && ip->i_extsize)
 		return ip->i_extsize;
 	if (XFS_IS_REALTIME_INODE(ip) &&
 	    ip->i_mount->m_sb.sb_rextsize > 1)
@@ -6523,7 +6524,13 @@ xfs_get_cowextsz_hint(
 	a = 0;
 	if (ip->i_diflags2 & XFS_DIFLAG2_COWEXTSIZE)
 		a = ip->i_cowextsize;
-	b = xfs_get_extsz_hint(ip);
+	if (XFS_IS_REALTIME_INODE(ip)) {
+		b = 0;
+		if (ip->i_diflags & XFS_DIFLAG_EXTSIZE)
+			b = ip->i_extsize;
+	} else {
+		b = xfs_get_extsz_hint(ip);
+	}
 
 	a = max(a, b);
 	if (a == 0)
diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
index 36ab06f8a3bc..299ce7fd11b0 100644
--- a/fs/xfs/libxfs/xfs_btree.c
+++ b/fs/xfs/libxfs/xfs_btree.c
@@ -35,6 +35,7 @@
 #include "xfs_rmap.h"
 #include "xfs_quota.h"
 #include "xfs_metafile.h"
+#include "xfs_rtrefcount_btree.h"
 
 /*
  * Btree magic numbers.
@@ -5535,6 +5536,9 @@ xfs_btree_init_cur_caches(void)
 	error = xfs_rtrmapbt_init_cur_cache();
 	if (error)
 		goto err;
+	error = xfs_rtrefcountbt_init_cur_cache();
+	if (error)
+		goto err;
 
 	return 0;
 err:
@@ -5552,6 +5556,7 @@ xfs_btree_destroy_cur_caches(void)
 	xfs_rmapbt_destroy_cur_cache();
 	xfs_refcountbt_destroy_cur_cache();
 	xfs_rtrmapbt_destroy_cur_cache();
+	xfs_rtrefcountbt_destroy_cur_cache();
 }
 
 /* Move the btree cursor before the first record. */
diff --git a/fs/xfs/libxfs/xfs_btree.h b/fs/xfs/libxfs/xfs_btree.h
index dbc047b2fb2c..355b304696e6 100644
--- a/fs/xfs/libxfs/xfs_btree.h
+++ b/fs/xfs/libxfs/xfs_btree.h
@@ -297,7 +297,7 @@ struct xfs_btree_cur
 		struct {
 			unsigned int	nr_ops;		/* # record updates */
 			unsigned int	shape_changes;	/* # of extent splits */
-		} bc_refc;	/* refcountbt */
+		} bc_refc;	/* refcountbt/rtrefcountbt */
 	};
 
 	/* Must be at the end of the struct! */
diff --git a/fs/xfs/libxfs/xfs_defer.h b/fs/xfs/libxfs/xfs_defer.h
index 1e2477eaa5a8..9effd95ddcd4 100644
--- a/fs/xfs/libxfs/xfs_defer.h
+++ b/fs/xfs/libxfs/xfs_defer.h
@@ -68,6 +68,7 @@ struct xfs_defer_op_type {
 
 extern const struct xfs_defer_op_type xfs_bmap_update_defer_type;
 extern const struct xfs_defer_op_type xfs_refcount_update_defer_type;
+extern const struct xfs_defer_op_type xfs_rtrefcount_update_defer_type;
 extern const struct xfs_defer_op_type xfs_rmap_update_defer_type;
 extern const struct xfs_defer_op_type xfs_rtrmap_update_defer_type;
 extern const struct xfs_defer_op_type xfs_extent_free_defer_type;
diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
index fba4e59aded4..b1007fb661ba 100644
--- a/fs/xfs/libxfs/xfs_format.h
+++ b/fs/xfs/libxfs/xfs_format.h
@@ -858,6 +858,7 @@ enum xfs_metafile_type {
 	XFS_METAFILE_RTBITMAP,		/* rt bitmap */
 	XFS_METAFILE_RTSUMMARY,		/* rt summary */
 	XFS_METAFILE_RTRMAP,		/* rt rmap */
+	XFS_METAFILE_RTREFCOUNT,	/* rt refcount */
 
 	XFS_METAFILE_MAX
 } __packed;
@@ -870,7 +871,8 @@ enum xfs_metafile_type {
 	{ XFS_METAFILE_PRJQUOTA,	"prjquota" }, \
 	{ XFS_METAFILE_RTBITMAP,	"rtbitmap" }, \
 	{ XFS_METAFILE_RTSUMMARY,	"rtsummary" }, \
-	{ XFS_METAFILE_RTRMAP,		"rtrmap" }
+	{ XFS_METAFILE_RTRMAP,		"rtrmap" }, \
+	{ XFS_METAFILE_RTREFCOUNT,	"rtrefcount" }
 
 /*
  * On-disk inode structure.
@@ -1790,12 +1792,29 @@ struct xfs_refcount_key {
 	__be32		rc_startblock;	/* starting block number */
 };
 
-#define MAXREFCOUNT	((xfs_nlink_t)~0U)
-#define MAXREFCEXTLEN	((xfs_extlen_t)~0U)
+#define XFS_REFC_REFCOUNT_MAX	((xfs_nlink_t)~0U)
+#define XFS_REFC_LEN_MAX	((xfs_extlen_t)~0U)
 
 /* btree pointer type */
 typedef __be32 xfs_refcount_ptr_t;
 
+/*
+ * Realtime Reference Count btree format definitions
+ *
+ * This is a btree for reference count records for realtime volumes
+ */
+#define	XFS_RTREFC_CRC_MAGIC	0x52434e54	/* 'RCNT' */
+
+/*
+ * rt refcount root header, on-disk form only.
+ */
+struct xfs_rtrefcount_root {
+	__be16		bb_level;	/* 0 is a leaf */
+	__be16		bb_numrecs;	/* current # of data records */
+};
+
+/* inode-rooted btree pointer type */
+typedef __be64 xfs_rtrefcount_ptr_t;
 
 /*
  * BMAP Btree format definitions
diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
index d42d3a5617e3..2c3171262b44 100644
--- a/fs/xfs/libxfs/xfs_fs.h
+++ b/fs/xfs/libxfs/xfs_fs.h
@@ -738,9 +738,10 @@ struct xfs_scrub_metadata {
 #define XFS_SCRUB_TYPE_METAPATH	29	/* metadata directory tree paths */
 #define XFS_SCRUB_TYPE_RGSUPER	30	/* realtime superblock */
 #define XFS_SCRUB_TYPE_RTRMAPBT	31	/* rtgroup reverse mapping btree */
+#define XFS_SCRUB_TYPE_RTREFCBT	32	/* realtime reference count btree */
 
 /* Number of scrub subcommands. */
-#define XFS_SCRUB_TYPE_NR	32
+#define XFS_SCRUB_TYPE_NR	33
 
 /*
  * This special type code only applies to the vectored scrub implementation.
@@ -831,9 +832,10 @@ struct xfs_scrub_vec_head {
 #define XFS_SCRUB_METAPATH_GRPQUOTA	(6)  /* group quota */
 #define XFS_SCRUB_METAPATH_PRJQUOTA	(7)  /* project quota */
 #define XFS_SCRUB_METAPATH_RTRMAPBT	(8)  /* realtime reverse mapping */
+#define XFS_SCRUB_METAPATH_RTREFCOUNTBT	(9)  /* realtime refcount */
 
 /* Number of metapath sm_ino values */
-#define XFS_SCRUB_METAPATH_NR		(9)
+#define XFS_SCRUB_METAPATH_NR		(10)
 
 /*
  * ioctl limits
@@ -996,6 +998,7 @@ struct xfs_rtgroup_geometry {
 #define XFS_RTGROUP_GEOM_SICK_BITMAP	(1U << 1)  /* rtbitmap */
 #define XFS_RTGROUP_GEOM_SICK_SUMMARY	(1U << 2)  /* rtsummary */
 #define XFS_RTGROUP_GEOM_SICK_RMAPBT	(1U << 3)  /* reverse mappings */
+#define XFS_RTGROUP_GEOM_SICK_REFCNTBT	(1U << 4)  /* reference counts */
 
 /*
  * ioctl commands that are used by Linux filesystems
diff --git a/fs/xfs/libxfs/xfs_health.h b/fs/xfs/libxfs/xfs_health.h
index 5c8a0aff6ba6..b31000f7190c 100644
--- a/fs/xfs/libxfs/xfs_health.h
+++ b/fs/xfs/libxfs/xfs_health.h
@@ -71,6 +71,7 @@ struct xfs_rtgroup;
 #define XFS_SICK_RG_BITMAP	(1 << 1)  /* rt group bitmap */
 #define XFS_SICK_RG_SUMMARY	(1 << 2)  /* rt groups summary */
 #define XFS_SICK_RG_RMAPBT	(1 << 3)  /* reverse mappings */
+#define XFS_SICK_RG_REFCNTBT	(1 << 4)  /* reference counts */
 
 /* Observable health issues for AG metadata. */
 #define XFS_SICK_AG_SB		(1 << 0)  /* superblock */
@@ -117,7 +118,8 @@ struct xfs_rtgroup;
 #define XFS_SICK_RG_PRIMARY	(XFS_SICK_RG_SUPER | \
 				 XFS_SICK_RG_BITMAP | \
 				 XFS_SICK_RG_SUMMARY | \
-				 XFS_SICK_RG_RMAPBT)
+				 XFS_SICK_RG_RMAPBT | \
+				 XFS_SICK_RG_REFCNTBT)
 
 #define XFS_SICK_AG_PRIMARY	(XFS_SICK_AG_SB | \
 				 XFS_SICK_AG_AGF | \
diff --git a/fs/xfs/libxfs/xfs_inode_buf.c b/fs/xfs/libxfs/xfs_inode_buf.c
index 17cb91b89fca..f24fa628fecf 100644
--- a/fs/xfs/libxfs/xfs_inode_buf.c
+++ b/fs/xfs/libxfs/xfs_inode_buf.c
@@ -456,6 +456,11 @@ xfs_dinode_verify_fork(
 			if (!xfs_has_rmapbt(mp))
 				return __this_address;
 			break;
+		case XFS_METAFILE_RTREFCOUNT:
+			/* same comment about growfs and rmap inodes applies */
+			if (!xfs_has_reflink(mp))
+				return __this_address;
+			break;
 		default:
 			return __this_address;
 		}
@@ -743,7 +748,8 @@ xfs_dinode_verify(
 		return __this_address;
 
 	/* don't let reflink and realtime mix */
-	if ((flags2 & XFS_DIFLAG2_REFLINK) && (flags & XFS_DIFLAG_REALTIME))
+	if ((flags2 & XFS_DIFLAG2_REFLINK) && (flags & XFS_DIFLAG_REALTIME) &&
+	    !xfs_has_rtreflink(mp))
 		return __this_address;
 
 	/* COW extent size hint validation */
@@ -904,11 +910,29 @@ xfs_inode_validate_cowextsize(
 	bool				rt_flag;
 	bool				hint_flag;
 	uint32_t			cowextsize_bytes;
+	uint32_t			blocksize_bytes;
 
 	rt_flag = (flags & XFS_DIFLAG_REALTIME);
 	hint_flag = (flags2 & XFS_DIFLAG2_COWEXTSIZE);
 	cowextsize_bytes = XFS_FSB_TO_B(mp, cowextsize);
 
+	/*
+	 * Similar to extent size hints, a directory can be configured to
+	 * propagate realtime status and a CoW extent size hint to newly
+	 * created files even if there is no realtime device, and the hints on
+	 * disk can become misaligned if the sysadmin changes the rt extent
+	 * size while adding the realtime device.
+	 *
+	 * Therefore, we can only enforce the rextsize alignment check against
+	 * regular realtime files, and rely on callers to decide when alignment
+	 * checks are appropriate, and fix things up as needed.
+	 */
+
+	if (rt_flag)
+		blocksize_bytes = XFS_FSB_TO_B(mp, mp->m_sb.sb_rextsize);
+	else
+		blocksize_bytes = mp->m_sb.sb_blocksize;
+
 	if (hint_flag && !xfs_has_reflink(mp))
 		return __this_address;
 
@@ -922,16 +946,13 @@ xfs_inode_validate_cowextsize(
 	if (mode && !hint_flag && cowextsize != 0)
 		return __this_address;
 
-	if (hint_flag && rt_flag)
-		return __this_address;
-
-	if (cowextsize_bytes % mp->m_sb.sb_blocksize)
+	if (cowextsize_bytes % blocksize_bytes)
 		return __this_address;
 
 	if (cowextsize > XFS_MAX_BMBT_EXTLEN)
 		return __this_address;
 
-	if (cowextsize > mp->m_sb.sb_agblocks / 2)
+	if (!rt_flag && cowextsize > mp->m_sb.sb_agblocks / 2)
 		return __this_address;
 
 	return NULL;
diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
index d9b3c182cb40..4f99b90add55 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.c
+++ b/fs/xfs/libxfs/xfs_inode_fork.c
@@ -28,6 +28,7 @@
 #include "xfs_health.h"
 #include "xfs_symlink_remote.h"
 #include "xfs_rtrmap_btree.h"
+#include "xfs_rtrefcount_btree.h"
 
 struct kmem_cache *xfs_ifork_cache;
 
@@ -272,6 +273,8 @@ xfs_iformat_data_fork(
 			switch (ip->i_metatype) {
 			case XFS_METAFILE_RTRMAP:
 				return xfs_iformat_rtrmap(ip, dip);
+			case XFS_METAFILE_RTREFCOUNT:
+				return xfs_iformat_rtrefcount(ip, dip);
 			default:
 				break;
 			}
@@ -620,6 +623,9 @@ xfs_iflush_fork(
 		case XFS_METAFILE_RTRMAP:
 			xfs_iflush_rtrmap(ip, dip);
 			break;
+		case XFS_METAFILE_RTREFCOUNT:
+			xfs_iflush_rtrefcount(ip, dip);
+			break;
 		default:
 			ASSERT(0);
 			break;
diff --git a/fs/xfs/libxfs/xfs_log_format.h b/fs/xfs/libxfs/xfs_log_format.h
index a7e0e479454d..ec7157eaba5f 100644
--- a/fs/xfs/libxfs/xfs_log_format.h
+++ b/fs/xfs/libxfs/xfs_log_format.h
@@ -252,6 +252,8 @@ typedef struct xfs_trans_header {
 #define	XFS_LI_EFD_RT		0x124b	/* realtime extent free done */
 #define	XFS_LI_RUI_RT		0x124c	/* realtime rmap update intent */
 #define	XFS_LI_RUD_RT		0x124d	/* realtime rmap update done */
+#define	XFS_LI_CUI_RT		0x124e	/* realtime refcount update intent */
+#define	XFS_LI_CUD_RT		0x124f	/* realtime refcount update done */
 
 #define XFS_LI_TYPE_DESC \
 	{ XFS_LI_EFI,		"XFS_LI_EFI" }, \
@@ -275,7 +277,9 @@ typedef struct xfs_trans_header {
 	{ XFS_LI_EFI_RT,	"XFS_LI_EFI_RT" }, \
 	{ XFS_LI_EFD_RT,	"XFS_LI_EFD_RT" }, \
 	{ XFS_LI_RUI_RT,	"XFS_LI_RUI_RT" }, \
-	{ XFS_LI_RUD_RT,	"XFS_LI_RUD_RT" }
+	{ XFS_LI_RUD_RT,	"XFS_LI_RUD_RT" }, \
+	{ XFS_LI_CUI_RT,	"XFS_LI_CUI_RT" }, \
+	{ XFS_LI_CUD_RT,	"XFS_LI_CUD_RT" }
 
 /*
  * Inode Log Item Format definitions.
diff --git a/fs/xfs/libxfs/xfs_log_recover.h b/fs/xfs/libxfs/xfs_log_recover.h
index abc705aff26d..66c7916fb5cd 100644
--- a/fs/xfs/libxfs/xfs_log_recover.h
+++ b/fs/xfs/libxfs/xfs_log_recover.h
@@ -81,6 +81,8 @@ extern const struct xlog_recover_item_ops xlog_rtefi_item_ops;
 extern const struct xlog_recover_item_ops xlog_rtefd_item_ops;
 extern const struct xlog_recover_item_ops xlog_rtrui_item_ops;
 extern const struct xlog_recover_item_ops xlog_rtrud_item_ops;
+extern const struct xlog_recover_item_ops xlog_rtcui_item_ops;
+extern const struct xlog_recover_item_ops xlog_rtcud_item_ops;
 
 /*
  * Macros, structures, prototypes for internal log manager use.
diff --git a/fs/xfs/libxfs/xfs_ondisk.h b/fs/xfs/libxfs/xfs_ondisk.h
index 07e2f5fb3a94..a85ecddaa48e 100644
--- a/fs/xfs/libxfs/xfs_ondisk.h
+++ b/fs/xfs/libxfs/xfs_ondisk.h
@@ -85,6 +85,8 @@ xfs_check_ondisk_structs(void)
 	XFS_CHECK_STRUCT_SIZE(struct xfs_rtbuf_blkinfo,		48);
 	XFS_CHECK_STRUCT_SIZE(xfs_rtrmap_ptr_t,			8);
 	XFS_CHECK_STRUCT_SIZE(struct xfs_rtrmap_root,		4);
+	XFS_CHECK_STRUCT_SIZE(xfs_rtrefcount_ptr_t,		8);
+	XFS_CHECK_STRUCT_SIZE(struct xfs_rtrefcount_root,	4);
 
 	/*
 	 * m68k has problems with struct xfs_attr_leaf_name_remote, but we pad
diff --git a/fs/xfs/libxfs/xfs_refcount.c b/fs/xfs/libxfs/xfs_refcount.c
index bbb86dc9a25c..cebe83f7842a 100644
--- a/fs/xfs/libxfs/xfs_refcount.c
+++ b/fs/xfs/libxfs/xfs_refcount.c
@@ -25,6 +25,9 @@
 #include "xfs_ag.h"
 #include "xfs_health.h"
 #include "xfs_refcount_item.h"
+#include "xfs_rtgroup.h"
+#include "xfs_rtalloc.h"
+#include "xfs_rtrefcount_btree.h"
 
 struct kmem_cache	*xfs_refcount_intent_cache;
 
@@ -128,7 +131,7 @@ xfs_refcount_check_irec(
 	struct xfs_perag		*pag,
 	const struct xfs_refcount_irec	*irec)
 {
-	if (irec->rc_blockcount == 0 || irec->rc_blockcount > MAXREFCEXTLEN)
+	if (irec->rc_blockcount == 0 || irec->rc_blockcount > XFS_REFC_LEN_MAX)
 		return __this_address;
 
 	if (!xfs_refcount_check_domain(irec))
@@ -138,12 +141,43 @@ xfs_refcount_check_irec(
 	if (!xfs_verify_agbext(pag, irec->rc_startblock, irec->rc_blockcount))
 		return __this_address;
 
-	if (irec->rc_refcount == 0 || irec->rc_refcount > MAXREFCOUNT)
+	if (irec->rc_refcount == 0 || irec->rc_refcount > XFS_REFC_REFCOUNT_MAX)
 		return __this_address;
 
 	return NULL;
 }
 
+xfs_failaddr_t
+xfs_rtrefcount_check_irec(
+	struct xfs_rtgroup		*rtg,
+	const struct xfs_refcount_irec	*irec)
+{
+	if (irec->rc_blockcount == 0 || irec->rc_blockcount > XFS_REFC_LEN_MAX)
+		return __this_address;
+
+	if (!xfs_refcount_check_domain(irec))
+		return __this_address;
+
+	/* check for valid extent range, including overflow */
+	if (!xfs_verify_rgbext(rtg, irec->rc_startblock, irec->rc_blockcount))
+		return __this_address;
+
+	if (irec->rc_refcount == 0 || irec->rc_refcount > XFS_REFC_REFCOUNT_MAX)
+		return __this_address;
+
+	return NULL;
+}
+
+static inline xfs_failaddr_t
+xfs_refcount_check_btrec(
+	struct xfs_btree_cur		*cur,
+	const struct xfs_refcount_irec	*irec)
+{
+	if (xfs_btree_is_rtrefcount(cur->bc_ops))
+		return xfs_rtrefcount_check_irec(to_rtg(cur->bc_group), irec);
+	return xfs_refcount_check_irec(to_perag(cur->bc_group), irec);
+}
+
 static inline int
 xfs_refcount_complain_bad_rec(
 	struct xfs_btree_cur		*cur,
@@ -152,9 +186,15 @@ xfs_refcount_complain_bad_rec(
 {
 	struct xfs_mount		*mp = cur->bc_mp;
 
-	xfs_warn(mp,
+	if (xfs_btree_is_rtrefcount(cur->bc_ops)) {
+		xfs_warn(mp,
+ "RT Refcount BTree record corruption in rtgroup %u detected at %pS!",
+				cur->bc_group->xg_gno, fa);
+	} else {
+		xfs_warn(mp,
  "Refcount BTree record corruption in AG %d detected at %pS!",
 				cur->bc_group->xg_gno, fa);
+	}
 	xfs_warn(mp,
 		"Start block 0x%x, block count 0x%x, references 0x%x",
 		irec->rc_startblock, irec->rc_blockcount, irec->rc_refcount);
@@ -180,7 +220,7 @@ xfs_refcount_get_rec(
 		return error;
 
 	xfs_refcount_btrec_to_irec(rec, irec);
-	fa = xfs_refcount_check_irec(to_perag(cur->bc_group), irec);
+	fa = xfs_refcount_check_btrec(cur, irec);
 	if (fa)
 		return xfs_refcount_complain_bad_rec(cur, fa, irec);
 
@@ -853,9 +893,9 @@ xfs_refc_merge_refcount(
 	const struct xfs_refcount_irec	*irec,
 	enum xfs_refc_adjust_op		adjust)
 {
-	/* Once a record hits MAXREFCOUNT, it is pinned there forever */
-	if (irec->rc_refcount == MAXREFCOUNT)
-		return MAXREFCOUNT;
+	/* Once a record hits XFS_REFC_REFCOUNT_MAX, it is pinned forever */
+	if (irec->rc_refcount == XFS_REFC_REFCOUNT_MAX)
+		return XFS_REFC_REFCOUNT_MAX;
 	return irec->rc_refcount + adjust;
 }
 
@@ -898,7 +938,7 @@ xfs_refc_want_merge_center(
 	 * hence we need to catch u32 addition overflows here.
 	 */
 	ulen += cleft->rc_blockcount + right->rc_blockcount;
-	if (ulen >= MAXREFCEXTLEN)
+	if (ulen >= XFS_REFC_LEN_MAX)
 		return false;
 
 	*ulenp = ulen;
@@ -933,7 +973,7 @@ xfs_refc_want_merge_left(
 	 * hence we need to catch u32 addition overflows here.
 	 */
 	ulen += cleft->rc_blockcount;
-	if (ulen >= MAXREFCEXTLEN)
+	if (ulen >= XFS_REFC_LEN_MAX)
 		return false;
 
 	return true;
@@ -967,7 +1007,7 @@ xfs_refc_want_merge_right(
 	 * hence we need to catch u32 addition overflows here.
 	 */
 	ulen += cright->rc_blockcount;
-	if (ulen >= MAXREFCEXTLEN)
+	if (ulen >= XFS_REFC_LEN_MAX)
 		return false;
 
 	return true;
@@ -1065,7 +1105,7 @@ xfs_refcount_still_have_space(
 	 */
 	overhead = xfs_allocfree_block_count(cur->bc_mp,
 				cur->bc_refc.shape_changes);
-	overhead += cur->bc_mp->m_refc_maxlevels;
+	overhead += cur->bc_maxlevels;
 	overhead *= cur->bc_mp->m_sb.sb_blocksize;
 
 	/*
@@ -1085,6 +1125,22 @@ xfs_refcount_still_have_space(
 		cur->bc_refc.nr_ops * XFS_REFCOUNT_ITEM_OVERHEAD;
 }
 
+/* Schedule an extent free. */
+static int
+xrefc_free_extent(
+	struct xfs_btree_cur		*cur,
+	struct xfs_refcount_irec	*rec)
+{
+	unsigned int			flags = 0;
+
+	if (xfs_btree_is_rtrefcount(cur->bc_ops))
+		flags |= XFS_FREE_EXTENT_REALTIME;
+
+	return xfs_free_extent_later(cur->bc_tp,
+			xfs_gbno_to_fsb(cur->bc_group, rec->rc_startblock),
+			rec->rc_blockcount, NULL, XFS_AG_RESV_NONE, flags);
+}
+
 /*
  * Adjust the refcounts of middle extents.  At this point we should have
  * split extents that crossed the adjustment range; merged with adjacent
@@ -1101,7 +1157,6 @@ xfs_refcount_adjust_extents(
 	struct xfs_refcount_irec	ext, tmp;
 	int				error;
 	int				found_rec, found_tmp;
-	xfs_fsblock_t			fsbno;
 
 	/* Merging did all the work already. */
 	if (*aglen == 0)
@@ -1117,7 +1172,7 @@ xfs_refcount_adjust_extents(
 		if (error)
 			goto out_error;
 		if (!found_rec || ext.rc_domain != XFS_REFC_DOMAIN_SHARED) {
-			ext.rc_startblock = cur->bc_mp->m_sb.sb_agblocks;
+			ext.rc_startblock = xfs_group_max_blocks(cur->bc_group);
 			ext.rc_blockcount = 0;
 			ext.rc_refcount = 0;
 			ext.rc_domain = XFS_REFC_DOMAIN_SHARED;
@@ -1154,11 +1209,7 @@ xfs_refcount_adjust_extents(
 					goto out_error;
 				}
 			} else {
-				fsbno = xfs_agbno_to_fsb(to_perag(cur->bc_group),
-						tmp.rc_startblock);
-				error = xfs_free_extent_later(cur->bc_tp, fsbno,
-						  tmp.rc_blockcount, NULL,
-						  XFS_AG_RESV_NONE, 0);
+				error = xrefc_free_extent(cur, &tmp);
 				if (error)
 					goto out_error;
 			}
@@ -1196,7 +1247,7 @@ xfs_refcount_adjust_extents(
 		 * Adjust the reference count and either update the tree
 		 * (incr) or free the blocks (decr).
 		 */
-		if (ext.rc_refcount == MAXREFCOUNT)
+		if (ext.rc_refcount == XFS_REFC_REFCOUNT_MAX)
 			goto skip;
 		ext.rc_refcount += adj;
 		trace_xfs_refcount_modify_extent(cur, &ext);
@@ -1216,11 +1267,7 @@ xfs_refcount_adjust_extents(
 			}
 			goto advloop;
 		} else {
-			fsbno = xfs_agbno_to_fsb(to_perag(cur->bc_group),
-					ext.rc_startblock);
-			error = xfs_free_extent_later(cur->bc_tp, fsbno,
-					ext.rc_blockcount, NULL,
-					XFS_AG_RESV_NONE, 0);
+			error = xrefc_free_extent(cur, &ext);
 			if (error)
 				goto out_error;
 		}
@@ -1417,12 +1464,122 @@ xfs_refcount_finish_one(
 }
 
 /*
+ * Set up a continuation a deferred rtrefcount operation by updating the
+ * intent.  Checks to make sure we're not going to run off the end of the
+ * rtgroup.
+ */
+static inline int
+xfs_rtrefcount_continue_op(
+	struct xfs_btree_cur		*cur,
+	struct xfs_refcount_intent	*ri,
+	xfs_agblock_t			new_agbno)
+{
+	struct xfs_mount		*mp = cur->bc_mp;
+	struct xfs_rtgroup		*rtg = to_rtg(ri->ri_group);
+
+	if (XFS_IS_CORRUPT(mp, !xfs_verify_rgbext(rtg, new_agbno,
+					ri->ri_blockcount))) {
+		xfs_btree_mark_sick(cur);
+		return -EFSCORRUPTED;
+	}
+
+	ri->ri_startblock = xfs_rgbno_to_rtb(rtg, new_agbno);
+
+	ASSERT(xfs_verify_rtbext(mp, ri->ri_startblock, ri->ri_blockcount));
+	return 0;
+}
+
+/*
+ * Process one of the deferred realtime refcount operations.  We pass back the
+ * btree cursor to maintain our lock on the btree between calls.
+ */
+int
+xfs_rtrefcount_finish_one(
+	struct xfs_trans		*tp,
+	struct xfs_refcount_intent	*ri,
+	struct xfs_btree_cur		**pcur)
+{
+	struct xfs_mount		*mp = tp->t_mountp;
+	struct xfs_rtgroup		*rtg = to_rtg(ri->ri_group);
+	struct xfs_btree_cur		*rcur = *pcur;
+	int				error = 0;
+	xfs_rgblock_t			bno;
+	unsigned long			nr_ops = 0;
+	int				shape_changes = 0;
+
+	bno = xfs_rtb_to_rgbno(mp, ri->ri_startblock);
+
+	trace_xfs_refcount_deferred(mp, ri);
+
+	if (XFS_TEST_ERROR(false, mp, XFS_ERRTAG_REFCOUNT_FINISH_ONE))
+		return -EIO;
+
+	/*
+	 * If we haven't gotten a cursor or the cursor AG doesn't match
+	 * the startblock, get one now.
+	 */
+	if (rcur != NULL && rcur->bc_group != ri->ri_group) {
+		nr_ops = rcur->bc_refc.nr_ops;
+		shape_changes = rcur->bc_refc.shape_changes;
+		xfs_btree_del_cursor(rcur, 0);
+		rcur = NULL;
+		*pcur = NULL;
+	}
+	if (rcur == NULL) {
+		xfs_rtgroup_lock(rtg, XFS_RTGLOCK_REFCOUNT);
+		xfs_rtgroup_trans_join(tp, rtg, XFS_RTGLOCK_REFCOUNT);
+		*pcur = rcur = xfs_rtrefcountbt_init_cursor(tp, rtg);
+
+		rcur->bc_refc.nr_ops = nr_ops;
+		rcur->bc_refc.shape_changes = shape_changes;
+	}
+
+	switch (ri->ri_type) {
+	case XFS_REFCOUNT_INCREASE:
+		error = xfs_refcount_adjust(rcur, &bno, &ri->ri_blockcount,
+				XFS_REFCOUNT_ADJUST_INCREASE);
+		if (error)
+			return error;
+		if (ri->ri_blockcount > 0)
+			error = xfs_rtrefcount_continue_op(rcur, ri, bno);
+		break;
+	case XFS_REFCOUNT_DECREASE:
+		error = xfs_refcount_adjust(rcur, &bno, &ri->ri_blockcount,
+				XFS_REFCOUNT_ADJUST_DECREASE);
+		if (error)
+			return error;
+		if (ri->ri_blockcount > 0)
+			error = xfs_rtrefcount_continue_op(rcur, ri, bno);
+		break;
+	case XFS_REFCOUNT_ALLOC_COW:
+		error = __xfs_refcount_cow_alloc(rcur, bno, ri->ri_blockcount);
+		if (error)
+			return error;
+		ri->ri_blockcount = 0;
+		break;
+	case XFS_REFCOUNT_FREE_COW:
+		error = __xfs_refcount_cow_free(rcur, bno, ri->ri_blockcount);
+		if (error)
+			return error;
+		ri->ri_blockcount = 0;
+		break;
+	default:
+		ASSERT(0);
+		return -EFSCORRUPTED;
+	}
+	if (!error && ri->ri_blockcount > 0)
+		trace_xfs_refcount_finish_one_leftover(mp, ri);
+	return error;
+}
+
+/*
  * Record a refcount intent for later processing.
  */
 static void
 __xfs_refcount_add(
 	struct xfs_trans		*tp,
 	enum xfs_refcount_intent_type	type,
+	bool				isrt,
 	xfs_fsblock_t			startblock,
 	xfs_extlen_t			blockcount)
 {
@@ -1434,6 +1591,7 @@ __xfs_refcount_add(
 	ri->ri_type = type;
 	ri->ri_startblock = startblock;
 	ri->ri_blockcount = blockcount;
+	ri->ri_realtime = isrt;
 
 	xfs_refcount_defer_add(tp, ri);
 }
@@ -1444,12 +1602,13 @@ __xfs_refcount_add(
 void
 xfs_refcount_increase_extent(
 	struct xfs_trans		*tp,
+	bool				isrt,
 	struct xfs_bmbt_irec		*PREV)
 {
 	if (!xfs_has_reflink(tp->t_mountp))
 		return;
 
-	__xfs_refcount_add(tp, XFS_REFCOUNT_INCREASE, PREV->br_startblock,
+	__xfs_refcount_add(tp, XFS_REFCOUNT_INCREASE, isrt, PREV->br_startblock,
 			PREV->br_blockcount);
 }
 
@@ -1459,12 +1618,13 @@ xfs_refcount_increase_extent(
 void
 xfs_refcount_decrease_extent(
 	struct xfs_trans		*tp,
+	bool				isrt,
 	struct xfs_bmbt_irec		*PREV)
 {
 	if (!xfs_has_reflink(tp->t_mountp))
 		return;
 
-	__xfs_refcount_add(tp, XFS_REFCOUNT_DECREASE, PREV->br_startblock,
+	__xfs_refcount_add(tp, XFS_REFCOUNT_DECREASE, isrt, PREV->br_startblock,
 			PREV->br_blockcount);
 }
 
@@ -1666,7 +1826,7 @@ xfs_refcount_adjust_cow_extents(
 		goto out_error;
 	}
 	if (!found_rec) {
-		ext.rc_startblock = cur->bc_mp->m_sb.sb_agblocks;
+		ext.rc_startblock = xfs_group_max_blocks(cur->bc_group);
 		ext.rc_blockcount = 0;
 		ext.rc_refcount = 0;
 		ext.rc_domain = XFS_REFC_DOMAIN_COW;
@@ -1820,6 +1980,7 @@ __xfs_refcount_cow_free(
 void
 xfs_refcount_alloc_cow_extent(
 	struct xfs_trans		*tp,
+	bool				isrt,
 	xfs_fsblock_t			fsb,
 	xfs_extlen_t			len)
 {
@@ -1828,16 +1989,17 @@ xfs_refcount_alloc_cow_extent(
 	if (!xfs_has_reflink(mp))
 		return;
 
-	__xfs_refcount_add(tp, XFS_REFCOUNT_ALLOC_COW, fsb, len);
+	__xfs_refcount_add(tp, XFS_REFCOUNT_ALLOC_COW, isrt, fsb, len);
 
 	/* Add rmap entry */
-	xfs_rmap_alloc_extent(tp, false, fsb, len, XFS_RMAP_OWN_COW);
+	xfs_rmap_alloc_extent(tp, isrt, fsb, len, XFS_RMAP_OWN_COW);
 }
 
 /* Forget a CoW staging event in the refcount btree. */
 void
 xfs_refcount_free_cow_extent(
 	struct xfs_trans		*tp,
+	bool				isrt,
 	xfs_fsblock_t			fsb,
 	xfs_extlen_t			len)
 {
@@ -1847,8 +2009,8 @@ xfs_refcount_free_cow_extent(
 		return;
 
 	/* Remove rmap entry */
-	xfs_rmap_free_extent(tp, false, fsb, len, XFS_RMAP_OWN_COW);
-	__xfs_refcount_add(tp, XFS_REFCOUNT_FREE_COW, fsb, len);
+	xfs_rmap_free_extent(tp, isrt, fsb, len, XFS_RMAP_OWN_COW);
+	__xfs_refcount_add(tp, XFS_REFCOUNT_FREE_COW, isrt, fsb, len);
 }
 
 struct xfs_refcount_recovery {
@@ -1877,8 +2039,7 @@ xfs_refcount_recover_extent(
 	INIT_LIST_HEAD(&rr->rr_list);
 	xfs_refcount_btrec_to_irec(rec, &rr->rr_rrec);
 
-	if (xfs_refcount_check_irec(to_perag(cur->bc_group), &rr->rr_rrec) !=
-			NULL ||
+	if (xfs_refcount_check_btrec(cur, &rr->rr_rrec) != NULL ||
 	    XFS_IS_CORRUPT(cur->bc_mp,
 			   rr->rr_rrec.rc_domain != XFS_REFC_DOMAIN_COW)) {
 		xfs_btree_mark_sick(cur);
@@ -1893,12 +2054,13 @@ xfs_refcount_recover_extent(
 /* Find and remove leftover CoW reservations. */
 int
 xfs_refcount_recover_cow_leftovers(
-	struct xfs_mount		*mp,
-	struct xfs_perag		*pag)
+	struct xfs_group		*xg)
 {
+	struct xfs_mount		*mp = xg->xg_mount;
+	bool				isrt = xg->xg_type == XG_TYPE_RTG;
 	struct xfs_trans		*tp;
 	struct xfs_btree_cur		*cur;
-	struct xfs_buf			*agbp;
+	struct xfs_buf			*agbp = NULL;
 	struct xfs_refcount_recovery	*rr, *n;
 	struct list_head		debris;
 	union xfs_btree_irec		low = {
@@ -1911,10 +2073,19 @@ xfs_refcount_recover_cow_leftovers(
 	xfs_fsblock_t			fsb;
 	int				error;
 
-	/* reflink filesystems mustn't have AGs larger than 2^31-1 blocks */
+	/* reflink filesystems must not have groups larger than 2^31-1 blocks */
+	BUILD_BUG_ON(XFS_MAX_RGBLOCKS >= XFS_REFC_COWFLAG);
 	BUILD_BUG_ON(XFS_MAX_CRC_AG_BLOCKS >= XFS_REFC_COWFLAG);
-	if (mp->m_sb.sb_agblocks > XFS_MAX_CRC_AG_BLOCKS)
-		return -EOPNOTSUPP;
+
+	if (isrt) {
+		if (!xfs_has_rtgroups(mp))
+			return 0;
+		if (xfs_group_max_blocks(xg) >= XFS_MAX_RGBLOCKS)
+			return -EOPNOTSUPP;
+	} else {
+		if (xfs_group_max_blocks(xg) > XFS_MAX_CRC_AG_BLOCKS)
+			return -EOPNOTSUPP;
+	}
 
 	INIT_LIST_HEAD(&debris);
 
@@ -1932,16 +2103,24 @@ xfs_refcount_recover_cow_leftovers(
 	if (error)
 		return error;
 
-	error = xfs_alloc_read_agf(pag, tp, 0, &agbp);
-	if (error)
-		goto out_trans;
-	cur = xfs_refcountbt_init_cursor(mp, tp, agbp, pag);
+	if (isrt) {
+		xfs_rtgroup_lock(to_rtg(xg), XFS_RTGLOCK_REFCOUNT);
+		cur = xfs_rtrefcountbt_init_cursor(tp, to_rtg(xg));
+	} else {
+		error = xfs_alloc_read_agf(to_perag(xg), tp, 0, &agbp);
+		if (error)
+			goto out_trans;
+		cur = xfs_refcountbt_init_cursor(mp, tp, agbp, to_perag(xg));
+	}
 
 	/* Find all the leftover CoW staging extents. */
 	error = xfs_btree_query_range(cur, &low, &high,
 			xfs_refcount_recover_extent, &debris);
 	xfs_btree_del_cursor(cur, error);
-	xfs_trans_brelse(tp, agbp);
+	if (agbp)
+		xfs_trans_brelse(tp, agbp);
+	else
+		xfs_rtgroup_unlock(to_rtg(xg), XFS_RTGLOCK_REFCOUNT);
 	xfs_trans_cancel(tp);
 	if (error)
 		goto out_free;
@@ -1954,14 +2133,15 @@ xfs_refcount_recover_cow_leftovers(
 			goto out_free;
 
 		/* Free the orphan record */
-		fsb = xfs_agbno_to_fsb(pag, rr->rr_rrec.rc_startblock);
-		xfs_refcount_free_cow_extent(tp, fsb,
+		fsb = xfs_gbno_to_fsb(xg, rr->rr_rrec.rc_startblock);
+		xfs_refcount_free_cow_extent(tp, isrt, fsb,
 				rr->rr_rrec.rc_blockcount);
 
 		/* Free the block. */
 		error = xfs_free_extent_later(tp, fsb,
 				rr->rr_rrec.rc_blockcount, NULL,
-				XFS_AG_RESV_NONE, 0);
+				XFS_AG_RESV_NONE,
+				isrt ? XFS_FREE_EXTENT_REALTIME : 0);
 		if (error)
 			goto out_trans;
 
@@ -2026,7 +2206,7 @@ xfs_refcount_query_range_helper(
 	xfs_failaddr_t			fa;
 
 	xfs_refcount_btrec_to_irec(rec, &irec);
-	fa = xfs_refcount_check_irec(to_perag(cur->bc_group), &irec);
+	fa = xfs_refcount_check_btrec(cur, &irec);
 	if (fa)
 		return xfs_refcount_complain_bad_rec(cur, fa, &irec);
 
diff --git a/fs/xfs/libxfs/xfs_refcount.h b/fs/xfs/libxfs/xfs_refcount.h
index 62d78afcf1f3..f2e299a716a4 100644
--- a/fs/xfs/libxfs/xfs_refcount.h
+++ b/fs/xfs/libxfs/xfs_refcount.h
@@ -12,6 +12,7 @@ struct xfs_perag;
 struct xfs_btree_cur;
 struct xfs_bmbt_irec;
 struct xfs_refcount_irec;
+struct xfs_rtgroup;
 
 extern int xfs_refcount_lookup_le(struct xfs_btree_cur *cur,
 		enum xfs_refc_domain domain, xfs_agblock_t bno, int *stat);
@@ -60,6 +61,7 @@ struct xfs_refcount_intent {
 	enum xfs_refcount_intent_type		ri_type;
 	xfs_extlen_t				ri_blockcount;
 	xfs_fsblock_t				ri_startblock;
+	bool					ri_realtime;
 };
 
 /* Check that the refcount is appropriate for the record domain. */
@@ -74,24 +76,25 @@ xfs_refcount_check_domain(
 	return true;
 }
 
-void xfs_refcount_increase_extent(struct xfs_trans *tp,
+void xfs_refcount_increase_extent(struct xfs_trans *tp, bool isrt,
 		struct xfs_bmbt_irec *irec);
-void xfs_refcount_decrease_extent(struct xfs_trans *tp,
+void xfs_refcount_decrease_extent(struct xfs_trans *tp, bool isrt,
 		struct xfs_bmbt_irec *irec);
 
-extern int xfs_refcount_finish_one(struct xfs_trans *tp,
+int xfs_refcount_finish_one(struct xfs_trans *tp,
+		struct xfs_refcount_intent *ri, struct xfs_btree_cur **pcur);
+int xfs_rtrefcount_finish_one(struct xfs_trans *tp,
 		struct xfs_refcount_intent *ri, struct xfs_btree_cur **pcur);
 
 extern int xfs_refcount_find_shared(struct xfs_btree_cur *cur,
 		xfs_agblock_t agbno, xfs_extlen_t aglen, xfs_agblock_t *fbno,
 		xfs_extlen_t *flen, bool find_end_of_shared);
 
-void xfs_refcount_alloc_cow_extent(struct xfs_trans *tp, xfs_fsblock_t fsb,
-		xfs_extlen_t len);
-void xfs_refcount_free_cow_extent(struct xfs_trans *tp, xfs_fsblock_t fsb,
-		xfs_extlen_t len);
-extern int xfs_refcount_recover_cow_leftovers(struct xfs_mount *mp,
-		struct xfs_perag *pag);
+void xfs_refcount_alloc_cow_extent(struct xfs_trans *tp, bool isrt,
+		xfs_fsblock_t fsb, xfs_extlen_t len);
+void xfs_refcount_free_cow_extent(struct xfs_trans *tp, bool isrt,
+		xfs_fsblock_t fsb, xfs_extlen_t len);
+int xfs_refcount_recover_cow_leftovers(struct xfs_group *xg);
 
 /*
  * While we're adjusting the refcounts records of an extent, we have
@@ -120,6 +123,8 @@ extern void xfs_refcount_btrec_to_irec(const union xfs_btree_rec *rec,
 		struct xfs_refcount_irec *irec);
 xfs_failaddr_t xfs_refcount_check_irec(struct xfs_perag *pag,
 		const struct xfs_refcount_irec *irec);
+xfs_failaddr_t xfs_rtrefcount_check_irec(struct xfs_rtgroup *rtg,
+		const struct xfs_refcount_irec *irec);
 extern int xfs_refcount_insert(struct xfs_btree_cur *cur,
 		struct xfs_refcount_irec *irec, int *stat);
 
diff --git a/fs/xfs/libxfs/xfs_rmap.c b/fs/xfs/libxfs/xfs_rmap.c
index f8415fd96cc2..3cdf50563fec 100644
--- a/fs/xfs/libxfs/xfs_rmap.c
+++ b/fs/xfs/libxfs/xfs_rmap.c
@@ -285,6 +285,13 @@ xfs_rtrmap_check_meta_irec(
 		if (irec->rm_blockcount != mp->m_sb.sb_rextsize)
 			return __this_address;
 		return NULL;
+	case XFS_RMAP_OWN_COW:
+		if (!xfs_has_rtreflink(mp))
+			return __this_address;
+		if (!xfs_verify_rgbext(rtg, irec->rm_startblock,
+					    irec->rm_blockcount))
+			return __this_address;
+		return NULL;
 	default:
 		return __this_address;
 	}
diff --git a/fs/xfs/libxfs/xfs_rtgroup.c b/fs/xfs/libxfs/xfs_rtgroup.c
index b7ed2d27d545..a6468e591232 100644
--- a/fs/xfs/libxfs/xfs_rtgroup.c
+++ b/fs/xfs/libxfs/xfs_rtgroup.c
@@ -34,6 +34,7 @@
 #include "xfs_metafile.h"
 #include "xfs_metadir.h"
 #include "xfs_rtrmap_btree.h"
+#include "xfs_rtrefcount_btree.h"
 
 /* Find the first usable fsblock in this rtgroup. */
 static inline uint32_t
@@ -206,6 +207,9 @@ xfs_rtgroup_lock(
 
 	if ((rtglock_flags & XFS_RTGLOCK_RMAP) && rtg_rmap(rtg))
 		xfs_ilock(rtg_rmap(rtg), XFS_ILOCK_EXCL);
+
+	if ((rtglock_flags & XFS_RTGLOCK_REFCOUNT) && rtg_refcount(rtg))
+		xfs_ilock(rtg_refcount(rtg), XFS_ILOCK_EXCL);
 }
 
 /* Unlock metadata inodes associated with this rt group. */
@@ -218,6 +222,9 @@ xfs_rtgroup_unlock(
 	ASSERT(!(rtglock_flags & XFS_RTGLOCK_BITMAP_SHARED) ||
 	       !(rtglock_flags & XFS_RTGLOCK_BITMAP));
 
+	if ((rtglock_flags & XFS_RTGLOCK_REFCOUNT) && rtg_refcount(rtg))
+		xfs_iunlock(rtg_refcount(rtg), XFS_ILOCK_EXCL);
+
 	if ((rtglock_flags & XFS_RTGLOCK_RMAP) && rtg_rmap(rtg))
 		xfs_iunlock(rtg_rmap(rtg), XFS_ILOCK_EXCL);
 
@@ -249,6 +256,9 @@ xfs_rtgroup_trans_join(
 
 	if ((rtglock_flags & XFS_RTGLOCK_RMAP) && rtg_rmap(rtg))
 		xfs_trans_ijoin(tp, rtg_rmap(rtg), XFS_ILOCK_EXCL);
+
+	if ((rtglock_flags & XFS_RTGLOCK_REFCOUNT) && rtg_refcount(rtg))
+		xfs_trans_ijoin(tp, rtg_refcount(rtg), XFS_ILOCK_EXCL);
 }
 
 /* Retrieve rt group geometry. */
@@ -367,6 +377,15 @@ static const struct xfs_rtginode_ops xfs_rtginode_ops[XFS_RTGI_MAX] = {
 		.enabled	= xfs_has_rmapbt,
 		.create		= xfs_rtrmapbt_create,
 	},
+	[XFS_RTGI_REFCOUNT] = {
+		.name		= "refcount",
+		.metafile_type	= XFS_METAFILE_RTREFCOUNT,
+		.sick		= XFS_SICK_RG_REFCNTBT,
+		.fmt_mask	= 1U << XFS_DINODE_FMT_META_BTREE,
+		/* same comment about growfs and rmap inodes applies here */
+		.enabled	= xfs_has_reflink,
+		.create		= xfs_rtrefcountbt_create,
+	},
 };
 
 /* Return the shortname of this rtgroup inode. */
diff --git a/fs/xfs/libxfs/xfs_rtgroup.h b/fs/xfs/libxfs/xfs_rtgroup.h
index 6ff222a05367..03f39d4e43fc 100644
--- a/fs/xfs/libxfs/xfs_rtgroup.h
+++ b/fs/xfs/libxfs/xfs_rtgroup.h
@@ -15,6 +15,7 @@ enum xfs_rtg_inodes {
 	XFS_RTGI_BITMAP,	/* allocation bitmap */
 	XFS_RTGI_SUMMARY,	/* allocation summary */
 	XFS_RTGI_RMAP,		/* rmap btree inode */
+	XFS_RTGI_REFCOUNT,	/* refcount btree inode */
 
 	XFS_RTGI_MAX,
 };
@@ -80,6 +81,11 @@ static inline struct xfs_inode *rtg_rmap(const struct xfs_rtgroup *rtg)
 	return rtg->rtg_inodes[XFS_RTGI_RMAP];
 }
 
+static inline struct xfs_inode *rtg_refcount(const struct xfs_rtgroup *rtg)
+{
+	return rtg->rtg_inodes[XFS_RTGI_REFCOUNT];
+}
+
 /* Passive rtgroup references */
 static inline struct xfs_rtgroup *
 xfs_rtgroup_get(
@@ -267,10 +273,13 @@ int xfs_update_last_rtgroup_size(struct xfs_mount *mp,
 #define XFS_RTGLOCK_BITMAP_SHARED	(1U << 1)
 /* Lock the rt rmap inode in exclusive mode */
 #define XFS_RTGLOCK_RMAP		(1U << 2)
+/* Lock the rt refcount inode in exclusive mode */
+#define XFS_RTGLOCK_REFCOUNT		(1U << 3)
 
 #define XFS_RTGLOCK_ALL_FLAGS	(XFS_RTGLOCK_BITMAP | \
 				 XFS_RTGLOCK_BITMAP_SHARED | \
-				 XFS_RTGLOCK_RMAP)
+				 XFS_RTGLOCK_RMAP | \
+				 XFS_RTGLOCK_REFCOUNT)
 
 void xfs_rtgroup_lock(struct xfs_rtgroup *rtg, unsigned int rtglock_flags);
 void xfs_rtgroup_unlock(struct xfs_rtgroup *rtg, unsigned int rtglock_flags);
diff --git a/fs/xfs/libxfs/xfs_rtrefcount_btree.c b/fs/xfs/libxfs/xfs_rtrefcount_btree.c
new file mode 100644
index 000000000000..3db5e7a4a945
--- /dev/null
+++ b/fs/xfs/libxfs/xfs_rtrefcount_btree.c
@@ -0,0 +1,757 @@
+// 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_log_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_bit.h"
+#include "xfs_sb.h"
+#include "xfs_mount.h"
+#include "xfs_defer.h"
+#include "xfs_inode.h"
+#include "xfs_trans.h"
+#include "xfs_alloc.h"
+#include "xfs_btree.h"
+#include "xfs_btree_staging.h"
+#include "xfs_rtrefcount_btree.h"
+#include "xfs_refcount.h"
+#include "xfs_trace.h"
+#include "xfs_cksum.h"
+#include "xfs_error.h"
+#include "xfs_extent_busy.h"
+#include "xfs_rtgroup.h"
+#include "xfs_rtbitmap.h"
+#include "xfs_metafile.h"
+#include "xfs_health.h"
+
+static struct kmem_cache	*xfs_rtrefcountbt_cur_cache;
+
+/*
+ * Realtime Reference Count btree.
+ *
+ * This is a btree used to track the owner(s) of a given extent in the realtime
+ * device.  See the comments in xfs_refcount_btree.c for more information.
+ *
+ * This tree is basically the same as the regular refcount btree except that
+ * it's rooted in an inode.
+ */
+
+static struct xfs_btree_cur *
+xfs_rtrefcountbt_dup_cursor(
+	struct xfs_btree_cur	*cur)
+{
+	return xfs_rtrefcountbt_init_cursor(cur->bc_tp, to_rtg(cur->bc_group));
+}
+
+STATIC int
+xfs_rtrefcountbt_get_minrecs(
+	struct xfs_btree_cur	*cur,
+	int			level)
+{
+	if (level == cur->bc_nlevels - 1) {
+		struct xfs_ifork	*ifp = xfs_btree_ifork_ptr(cur);
+
+		return xfs_rtrefcountbt_maxrecs(cur->bc_mp, ifp->if_broot_bytes,
+				level == 0) / 2;
+	}
+
+	return cur->bc_mp->m_rtrefc_mnr[level != 0];
+}
+
+STATIC int
+xfs_rtrefcountbt_get_maxrecs(
+	struct xfs_btree_cur	*cur,
+	int			level)
+{
+	if (level == cur->bc_nlevels - 1) {
+		struct xfs_ifork	*ifp = xfs_btree_ifork_ptr(cur);
+
+		return xfs_rtrefcountbt_maxrecs(cur->bc_mp, ifp->if_broot_bytes,
+				level == 0);
+	}
+
+	return cur->bc_mp->m_rtrefc_mxr[level != 0];
+}
+
+/*
+ * Calculate number of records in a realtime refcount btree inode root.
+ */
+unsigned int
+xfs_rtrefcountbt_droot_maxrecs(
+	unsigned int		blocklen,
+	bool			leaf)
+{
+	blocklen -= sizeof(struct xfs_rtrefcount_root);
+
+	if (leaf)
+		return blocklen / sizeof(struct xfs_refcount_rec);
+	return blocklen / (2 * sizeof(struct xfs_refcount_key) +
+			sizeof(xfs_rtrefcount_ptr_t));
+}
+
+/*
+ * Get the maximum records we could store in the on-disk format.
+ *
+ * For non-root nodes this is equivalent to xfs_rtrefcountbt_get_maxrecs, but
+ * for the root node this checks the available space in the dinode fork so that
+ * we can resize the in-memory buffer to match it.  After a resize to the
+ * maximum size this function returns the same value as
+ * xfs_rtrefcountbt_get_maxrecs for the root node, too.
+ */
+STATIC int
+xfs_rtrefcountbt_get_dmaxrecs(
+	struct xfs_btree_cur	*cur,
+	int			level)
+{
+	if (level != cur->bc_nlevels - 1)
+		return cur->bc_mp->m_rtrefc_mxr[level != 0];
+	return xfs_rtrefcountbt_droot_maxrecs(cur->bc_ino.forksize, level == 0);
+}
+
+STATIC void
+xfs_rtrefcountbt_init_key_from_rec(
+	union xfs_btree_key		*key,
+	const union xfs_btree_rec	*rec)
+{
+	key->refc.rc_startblock = rec->refc.rc_startblock;
+}
+
+STATIC void
+xfs_rtrefcountbt_init_high_key_from_rec(
+	union xfs_btree_key		*key,
+	const union xfs_btree_rec	*rec)
+{
+	__u32				x;
+
+	x = be32_to_cpu(rec->refc.rc_startblock);
+	x += be32_to_cpu(rec->refc.rc_blockcount) - 1;
+	key->refc.rc_startblock = cpu_to_be32(x);
+}
+
+STATIC void
+xfs_rtrefcountbt_init_rec_from_cur(
+	struct xfs_btree_cur	*cur,
+	union xfs_btree_rec	*rec)
+{
+	const struct xfs_refcount_irec *irec = &cur->bc_rec.rc;
+	uint32_t		start;
+
+	start = xfs_refcount_encode_startblock(irec->rc_startblock,
+			irec->rc_domain);
+	rec->refc.rc_startblock = cpu_to_be32(start);
+	rec->refc.rc_blockcount = cpu_to_be32(cur->bc_rec.rc.rc_blockcount);
+	rec->refc.rc_refcount = cpu_to_be32(cur->bc_rec.rc.rc_refcount);
+}
+
+STATIC void
+xfs_rtrefcountbt_init_ptr_from_cur(
+	struct xfs_btree_cur	*cur,
+	union xfs_btree_ptr	*ptr)
+{
+	ptr->l = 0;
+}
+
+STATIC int64_t
+xfs_rtrefcountbt_key_diff(
+	struct xfs_btree_cur		*cur,
+	const union xfs_btree_key	*key)
+{
+	const struct xfs_refcount_key	*kp = &key->refc;
+	const struct xfs_refcount_irec	*irec = &cur->bc_rec.rc;
+	uint32_t			start;
+
+	start = xfs_refcount_encode_startblock(irec->rc_startblock,
+			irec->rc_domain);
+	return (int64_t)be32_to_cpu(kp->rc_startblock) - start;
+}
+
+STATIC int64_t
+xfs_rtrefcountbt_diff_two_keys(
+	struct xfs_btree_cur		*cur,
+	const union xfs_btree_key	*k1,
+	const union xfs_btree_key	*k2,
+	const union xfs_btree_key	*mask)
+{
+	ASSERT(!mask || mask->refc.rc_startblock);
+
+	return (int64_t)be32_to_cpu(k1->refc.rc_startblock) -
+			be32_to_cpu(k2->refc.rc_startblock);
+}
+
+static xfs_failaddr_t
+xfs_rtrefcountbt_verify(
+	struct xfs_buf		*bp)
+{
+	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
+	xfs_failaddr_t		fa;
+	int			level;
+
+	if (!xfs_verify_magic(bp, block->bb_magic))
+		return __this_address;
+
+	if (!xfs_has_reflink(mp))
+		return __this_address;
+	fa = xfs_btree_fsblock_v5hdr_verify(bp, XFS_RMAP_OWN_UNKNOWN);
+	if (fa)
+		return fa;
+	level = be16_to_cpu(block->bb_level);
+	if (level > mp->m_rtrefc_maxlevels)
+		return __this_address;
+
+	return xfs_btree_fsblock_verify(bp, mp->m_rtrefc_mxr[level != 0]);
+}
+
+static void
+xfs_rtrefcountbt_read_verify(
+	struct xfs_buf	*bp)
+{
+	xfs_failaddr_t	fa;
+
+	if (!xfs_btree_fsblock_verify_crc(bp))
+		xfs_verifier_error(bp, -EFSBADCRC, __this_address);
+	else {
+		fa = xfs_rtrefcountbt_verify(bp);
+		if (fa)
+			xfs_verifier_error(bp, -EFSCORRUPTED, fa);
+	}
+
+	if (bp->b_error)
+		trace_xfs_btree_corrupt(bp, _RET_IP_);
+}
+
+static void
+xfs_rtrefcountbt_write_verify(
+	struct xfs_buf	*bp)
+{
+	xfs_failaddr_t	fa;
+
+	fa = xfs_rtrefcountbt_verify(bp);
+	if (fa) {
+		trace_xfs_btree_corrupt(bp, _RET_IP_);
+		xfs_verifier_error(bp, -EFSCORRUPTED, fa);
+		return;
+	}
+	xfs_btree_fsblock_calc_crc(bp);
+
+}
+
+const struct xfs_buf_ops xfs_rtrefcountbt_buf_ops = {
+	.name			= "xfs_rtrefcountbt",
+	.magic			= { 0, cpu_to_be32(XFS_RTREFC_CRC_MAGIC) },
+	.verify_read		= xfs_rtrefcountbt_read_verify,
+	.verify_write		= xfs_rtrefcountbt_write_verify,
+	.verify_struct		= xfs_rtrefcountbt_verify,
+};
+
+STATIC int
+xfs_rtrefcountbt_keys_inorder(
+	struct xfs_btree_cur		*cur,
+	const union xfs_btree_key	*k1,
+	const union xfs_btree_key	*k2)
+{
+	return be32_to_cpu(k1->refc.rc_startblock) <
+	       be32_to_cpu(k2->refc.rc_startblock);
+}
+
+STATIC int
+xfs_rtrefcountbt_recs_inorder(
+	struct xfs_btree_cur		*cur,
+	const union xfs_btree_rec	*r1,
+	const union xfs_btree_rec	*r2)
+{
+	return  be32_to_cpu(r1->refc.rc_startblock) +
+		be32_to_cpu(r1->refc.rc_blockcount) <=
+		be32_to_cpu(r2->refc.rc_startblock);
+}
+
+STATIC enum xbtree_key_contig
+xfs_rtrefcountbt_keys_contiguous(
+	struct xfs_btree_cur		*cur,
+	const union xfs_btree_key	*key1,
+	const union xfs_btree_key	*key2,
+	const union xfs_btree_key	*mask)
+{
+	ASSERT(!mask || mask->refc.rc_startblock);
+
+	return xbtree_key_contig(be32_to_cpu(key1->refc.rc_startblock),
+				 be32_to_cpu(key2->refc.rc_startblock));
+}
+
+static inline void
+xfs_rtrefcountbt_move_ptrs(
+	struct xfs_mount	*mp,
+	struct xfs_btree_block	*broot,
+	short			old_size,
+	size_t			new_size,
+	unsigned int		numrecs)
+{
+	void			*dptr;
+	void			*sptr;
+
+	sptr = xfs_rtrefcount_broot_ptr_addr(mp, broot, 1, old_size);
+	dptr = xfs_rtrefcount_broot_ptr_addr(mp, broot, 1, new_size);
+	memmove(dptr, sptr, numrecs * sizeof(xfs_rtrefcount_ptr_t));
+}
+
+static struct xfs_btree_block *
+xfs_rtrefcountbt_broot_realloc(
+	struct xfs_btree_cur	*cur,
+	unsigned int		new_numrecs)
+{
+	struct xfs_mount	*mp = cur->bc_mp;
+	struct xfs_ifork	*ifp = xfs_btree_ifork_ptr(cur);
+	struct xfs_btree_block	*broot;
+	unsigned int		new_size;
+	unsigned int		old_size = ifp->if_broot_bytes;
+	const unsigned int	level = cur->bc_nlevels - 1;
+
+	new_size = xfs_rtrefcount_broot_space_calc(mp, level, new_numrecs);
+
+	/* Handle the nop case quietly. */
+	if (new_size == old_size)
+		return ifp->if_broot;
+
+	if (new_size > old_size) {
+		unsigned int	old_numrecs;
+
+		/*
+		 * If there wasn't any memory allocated before, just allocate
+		 * it now and get out.
+		 */
+		if (old_size == 0)
+			return xfs_broot_realloc(ifp, new_size);
+
+		/*
+		 * If there is already an existing if_broot, then we need to
+		 * realloc it and possibly move the node block pointers because
+		 * those are not butted up against the btree block header.
+		 */
+		old_numrecs = xfs_rtrefcountbt_maxrecs(mp, old_size, level);
+		broot = xfs_broot_realloc(ifp, new_size);
+		if (level > 0)
+			xfs_rtrefcountbt_move_ptrs(mp, broot, old_size,
+					new_size, old_numrecs);
+		goto out_broot;
+	}
+
+	/*
+	 * We're reducing numrecs.  If we're going all the way to zero, just
+	 * free the block.
+	 */
+	ASSERT(ifp->if_broot != NULL && old_size > 0);
+	if (new_size == 0)
+		return xfs_broot_realloc(ifp, 0);
+
+	/*
+	 * Shrink the btree root by possibly moving the rtrmapbt pointers,
+	 * since they are not butted up against the btree block header.  Then
+	 * reallocate broot.
+	 */
+	if (level > 0)
+		xfs_rtrefcountbt_move_ptrs(mp, ifp->if_broot, old_size,
+				new_size, new_numrecs);
+	broot = xfs_broot_realloc(ifp, new_size);
+
+out_broot:
+	ASSERT(xfs_rtrefcount_droot_space(broot) <=
+	       xfs_inode_fork_size(cur->bc_ino.ip, cur->bc_ino.whichfork));
+	return broot;
+}
+
+const struct xfs_btree_ops xfs_rtrefcountbt_ops = {
+	.name			= "rtrefcount",
+	.type			= XFS_BTREE_TYPE_INODE,
+	.geom_flags		= XFS_BTGEO_IROOT_RECORDS,
+
+	.rec_len		= sizeof(struct xfs_refcount_rec),
+	.key_len		= sizeof(struct xfs_refcount_key),
+	.ptr_len		= XFS_BTREE_LONG_PTR_LEN,
+
+	.lru_refs		= XFS_REFC_BTREE_REF,
+	.statoff		= XFS_STATS_CALC_INDEX(xs_rtrefcbt_2),
+	.sick_mask		= XFS_SICK_RG_REFCNTBT,
+
+	.dup_cursor		= xfs_rtrefcountbt_dup_cursor,
+	.alloc_block		= xfs_btree_alloc_metafile_block,
+	.free_block		= xfs_btree_free_metafile_block,
+	.get_minrecs		= xfs_rtrefcountbt_get_minrecs,
+	.get_maxrecs		= xfs_rtrefcountbt_get_maxrecs,
+	.get_dmaxrecs		= xfs_rtrefcountbt_get_dmaxrecs,
+	.init_key_from_rec	= xfs_rtrefcountbt_init_key_from_rec,
+	.init_high_key_from_rec	= xfs_rtrefcountbt_init_high_key_from_rec,
+	.init_rec_from_cur	= xfs_rtrefcountbt_init_rec_from_cur,
+	.init_ptr_from_cur	= xfs_rtrefcountbt_init_ptr_from_cur,
+	.key_diff		= xfs_rtrefcountbt_key_diff,
+	.buf_ops		= &xfs_rtrefcountbt_buf_ops,
+	.diff_two_keys		= xfs_rtrefcountbt_diff_two_keys,
+	.keys_inorder		= xfs_rtrefcountbt_keys_inorder,
+	.recs_inorder		= xfs_rtrefcountbt_recs_inorder,
+	.keys_contiguous	= xfs_rtrefcountbt_keys_contiguous,
+	.broot_realloc		= xfs_rtrefcountbt_broot_realloc,
+};
+
+/* Allocate a new rt refcount btree cursor. */
+struct xfs_btree_cur *
+xfs_rtrefcountbt_init_cursor(
+	struct xfs_trans	*tp,
+	struct xfs_rtgroup	*rtg)
+{
+	struct xfs_inode	*ip = rtg_refcount(rtg);
+	struct xfs_mount	*mp = rtg_mount(rtg);
+	struct xfs_btree_cur	*cur;
+
+	xfs_assert_ilocked(ip, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL);
+
+	cur = xfs_btree_alloc_cursor(mp, tp, &xfs_rtrefcountbt_ops,
+			mp->m_rtrefc_maxlevels, xfs_rtrefcountbt_cur_cache);
+
+	cur->bc_ino.ip = ip;
+	cur->bc_refc.nr_ops = 0;
+	cur->bc_refc.shape_changes = 0;
+	cur->bc_group = xfs_group_hold(rtg_group(rtg));
+	cur->bc_nlevels = be16_to_cpu(ip->i_df.if_broot->bb_level) + 1;
+	cur->bc_ino.forksize = xfs_inode_fork_size(ip, XFS_DATA_FORK);
+	cur->bc_ino.whichfork = XFS_DATA_FORK;
+	return cur;
+}
+
+/*
+ * Install a new rt reverse mapping btree root.  Caller is responsible for
+ * invalidating and freeing the old btree blocks.
+ */
+void
+xfs_rtrefcountbt_commit_staged_btree(
+	struct xfs_btree_cur	*cur,
+	struct xfs_trans	*tp)
+{
+	struct xbtree_ifakeroot	*ifake = cur->bc_ino.ifake;
+	struct xfs_ifork	*ifp;
+	int			flags = XFS_ILOG_CORE | XFS_ILOG_DBROOT;
+
+	ASSERT(cur->bc_flags & XFS_BTREE_STAGING);
+	ASSERT(ifake->if_fork->if_format == XFS_DINODE_FMT_META_BTREE);
+
+	/*
+	 * Free any resources hanging off the real fork, then shallow-copy the
+	 * staging fork's contents into the real fork to transfer everything
+	 * we just built.
+	 */
+	ifp = xfs_ifork_ptr(cur->bc_ino.ip, XFS_DATA_FORK);
+	xfs_idestroy_fork(ifp);
+	memcpy(ifp, ifake->if_fork, sizeof(struct xfs_ifork));
+
+	cur->bc_ino.ip->i_projid = cur->bc_group->xg_gno;
+	xfs_trans_log_inode(tp, cur->bc_ino.ip, flags);
+	xfs_btree_commit_ifakeroot(cur, tp, XFS_DATA_FORK);
+}
+
+/* Calculate number of records in a realtime refcount btree block. */
+static inline unsigned int
+xfs_rtrefcountbt_block_maxrecs(
+	unsigned int		blocklen,
+	bool			leaf)
+{
+
+	if (leaf)
+		return blocklen / sizeof(struct xfs_refcount_rec);
+	return blocklen / (sizeof(struct xfs_refcount_key) +
+			   sizeof(xfs_rtrefcount_ptr_t));
+}
+
+/*
+ * Calculate number of records in an refcount btree block.
+ */
+unsigned int
+xfs_rtrefcountbt_maxrecs(
+	struct xfs_mount	*mp,
+	unsigned int		blocklen,
+	bool			leaf)
+{
+	blocklen -= XFS_RTREFCOUNT_BLOCK_LEN;
+	return xfs_rtrefcountbt_block_maxrecs(blocklen, leaf);
+}
+
+/* Compute the max possible height for realtime refcount btrees. */
+unsigned int
+xfs_rtrefcountbt_maxlevels_ondisk(void)
+{
+	unsigned int		minrecs[2];
+	unsigned int		blocklen;
+
+	blocklen = XFS_MIN_CRC_BLOCKSIZE - XFS_BTREE_LBLOCK_CRC_LEN;
+
+	minrecs[0] = xfs_rtrefcountbt_block_maxrecs(blocklen, true) / 2;
+	minrecs[1] = xfs_rtrefcountbt_block_maxrecs(blocklen, false) / 2;
+
+	/* We need at most one record for every block in an rt group. */
+	return xfs_btree_compute_maxlevels(minrecs, XFS_MAX_RGBLOCKS);
+}
+
+int __init
+xfs_rtrefcountbt_init_cur_cache(void)
+{
+	xfs_rtrefcountbt_cur_cache = kmem_cache_create("xfs_rtrefcountbt_cur",
+			xfs_btree_cur_sizeof(
+					xfs_rtrefcountbt_maxlevels_ondisk()),
+			0, 0, NULL);
+
+	if (!xfs_rtrefcountbt_cur_cache)
+		return -ENOMEM;
+	return 0;
+}
+
+void
+xfs_rtrefcountbt_destroy_cur_cache(void)
+{
+	kmem_cache_destroy(xfs_rtrefcountbt_cur_cache);
+	xfs_rtrefcountbt_cur_cache = NULL;
+}
+
+/* Compute the maximum height of a realtime refcount btree. */
+void
+xfs_rtrefcountbt_compute_maxlevels(
+	struct xfs_mount	*mp)
+{
+	unsigned int		d_maxlevels, r_maxlevels;
+
+	if (!xfs_has_rtreflink(mp)) {
+		mp->m_rtrefc_maxlevels = 0;
+		return;
+	}
+
+	/*
+	 * The realtime refcountbt lives on the data device, which means that
+	 * its maximum height is constrained by the size of the data device and
+	 * the height required to store one refcount record for each rtextent
+	 * in an rt group.
+	 */
+	d_maxlevels = xfs_btree_space_to_height(mp->m_rtrefc_mnr,
+				mp->m_sb.sb_dblocks);
+	r_maxlevels = xfs_btree_compute_maxlevels(mp->m_rtrefc_mnr,
+				mp->m_sb.sb_rgextents);
+
+	/* Add one level to handle the inode root level. */
+	mp->m_rtrefc_maxlevels = min(d_maxlevels, r_maxlevels) + 1;
+}
+
+/* Calculate the rtrefcount btree size for some records. */
+unsigned long long
+xfs_rtrefcountbt_calc_size(
+	struct xfs_mount	*mp,
+	unsigned long long	len)
+{
+	return xfs_btree_calc_size(mp->m_rtrefc_mnr, len);
+}
+
+/*
+ * Calculate the maximum refcount btree size.
+ */
+static unsigned long long
+xfs_rtrefcountbt_max_size(
+	struct xfs_mount	*mp,
+	xfs_rtblock_t		rtblocks)
+{
+	/* Bail out if we're uninitialized, which can happen in mkfs. */
+	if (mp->m_rtrefc_mxr[0] == 0)
+		return 0;
+
+	return xfs_rtrefcountbt_calc_size(mp, rtblocks);
+}
+
+/*
+ * Figure out how many blocks to reserve and how many are used by this btree.
+ * We need enough space to hold one record for every rt extent in the rtgroup.
+ */
+xfs_filblks_t
+xfs_rtrefcountbt_calc_reserves(
+	struct xfs_mount	*mp)
+{
+	if (!xfs_has_rtreflink(mp))
+		return 0;
+
+	return xfs_rtrefcountbt_max_size(mp, mp->m_sb.sb_rgextents);
+}
+
+/*
+ * Convert on-disk form of btree root to in-memory form.
+ */
+STATIC void
+xfs_rtrefcountbt_from_disk(
+	struct xfs_inode		*ip,
+	struct xfs_rtrefcount_root	*dblock,
+	int				dblocklen,
+	struct xfs_btree_block		*rblock)
+{
+	struct xfs_mount		*mp = ip->i_mount;
+	struct xfs_refcount_key	*fkp;
+	__be64				*fpp;
+	struct xfs_refcount_key	*tkp;
+	__be64				*tpp;
+	struct xfs_refcount_rec	*frp;
+	struct xfs_refcount_rec	*trp;
+	unsigned int			numrecs;
+	unsigned int			maxrecs;
+	unsigned int			rblocklen;
+
+	rblocklen = xfs_rtrefcount_broot_space(mp, dblock);
+
+	xfs_btree_init_block(mp, rblock, &xfs_rtrefcountbt_ops, 0, 0,
+			ip->i_ino);
+
+	rblock->bb_level = dblock->bb_level;
+	rblock->bb_numrecs = dblock->bb_numrecs;
+
+	if (be16_to_cpu(rblock->bb_level) > 0) {
+		maxrecs = xfs_rtrefcountbt_droot_maxrecs(dblocklen, false);
+		fkp = xfs_rtrefcount_droot_key_addr(dblock, 1);
+		tkp = xfs_rtrefcount_key_addr(rblock, 1);
+		fpp = xfs_rtrefcount_droot_ptr_addr(dblock, 1, maxrecs);
+		tpp = xfs_rtrefcount_broot_ptr_addr(mp, rblock, 1, rblocklen);
+		numrecs = be16_to_cpu(dblock->bb_numrecs);
+		memcpy(tkp, fkp, 2 * sizeof(*fkp) * numrecs);
+		memcpy(tpp, fpp, sizeof(*fpp) * numrecs);
+	} else {
+		frp = xfs_rtrefcount_droot_rec_addr(dblock, 1);
+		trp = xfs_rtrefcount_rec_addr(rblock, 1);
+		numrecs = be16_to_cpu(dblock->bb_numrecs);
+		memcpy(trp, frp, sizeof(*frp) * numrecs);
+	}
+}
+
+/* Load a realtime reference count btree root in from disk. */
+int
+xfs_iformat_rtrefcount(
+	struct xfs_inode	*ip,
+	struct xfs_dinode	*dip)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_rtrefcount_root *dfp = XFS_DFORK_PTR(dip, XFS_DATA_FORK);
+	struct xfs_btree_block	*broot;
+	unsigned int		numrecs;
+	unsigned int		level;
+	int			dsize;
+
+	/*
+	 * growfs must create the rtrefcount inodes before adding a realtime
+	 * volume to the filesystem, so we cannot use the rtrefcount predicate
+	 * here.
+	 */
+	if (!xfs_has_reflink(ip->i_mount)) {
+		xfs_inode_mark_sick(ip, XFS_SICK_INO_CORE);
+		return -EFSCORRUPTED;
+	}
+
+	dsize = XFS_DFORK_SIZE(dip, mp, XFS_DATA_FORK);
+	numrecs = be16_to_cpu(dfp->bb_numrecs);
+	level = be16_to_cpu(dfp->bb_level);
+
+	if (level > mp->m_rtrefc_maxlevels ||
+	    xfs_rtrefcount_droot_space_calc(level, numrecs) > dsize) {
+		xfs_inode_mark_sick(ip, XFS_SICK_INO_CORE);
+		return -EFSCORRUPTED;
+	}
+
+	broot = xfs_broot_alloc(xfs_ifork_ptr(ip, XFS_DATA_FORK),
+			xfs_rtrefcount_broot_space_calc(mp, level, numrecs));
+	if (broot)
+		xfs_rtrefcountbt_from_disk(ip, dfp, dsize, broot);
+	return 0;
+}
+
+/*
+ * Convert in-memory form of btree root to on-disk form.
+ */
+void
+xfs_rtrefcountbt_to_disk(
+	struct xfs_mount		*mp,
+	struct xfs_btree_block		*rblock,
+	int				rblocklen,
+	struct xfs_rtrefcount_root	*dblock,
+	int				dblocklen)
+{
+	struct xfs_refcount_key	*fkp;
+	__be64				*fpp;
+	struct xfs_refcount_key	*tkp;
+	__be64				*tpp;
+	struct xfs_refcount_rec	*frp;
+	struct xfs_refcount_rec	*trp;
+	unsigned int			maxrecs;
+	unsigned int			numrecs;
+
+	ASSERT(rblock->bb_magic == cpu_to_be32(XFS_RTREFC_CRC_MAGIC));
+	ASSERT(uuid_equal(&rblock->bb_u.l.bb_uuid, &mp->m_sb.sb_meta_uuid));
+	ASSERT(rblock->bb_u.l.bb_blkno == cpu_to_be64(XFS_BUF_DADDR_NULL));
+	ASSERT(rblock->bb_u.l.bb_leftsib == cpu_to_be64(NULLFSBLOCK));
+	ASSERT(rblock->bb_u.l.bb_rightsib == cpu_to_be64(NULLFSBLOCK));
+
+	dblock->bb_level = rblock->bb_level;
+	dblock->bb_numrecs = rblock->bb_numrecs;
+
+	if (be16_to_cpu(rblock->bb_level) > 0) {
+		maxrecs = xfs_rtrefcountbt_droot_maxrecs(dblocklen, false);
+		fkp = xfs_rtrefcount_key_addr(rblock, 1);
+		tkp = xfs_rtrefcount_droot_key_addr(dblock, 1);
+		fpp = xfs_rtrefcount_broot_ptr_addr(mp, rblock, 1, rblocklen);
+		tpp = xfs_rtrefcount_droot_ptr_addr(dblock, 1, maxrecs);
+		numrecs = be16_to_cpu(rblock->bb_numrecs);
+		memcpy(tkp, fkp, 2 * sizeof(*fkp) * numrecs);
+		memcpy(tpp, fpp, sizeof(*fpp) * numrecs);
+	} else {
+		frp = xfs_rtrefcount_rec_addr(rblock, 1);
+		trp = xfs_rtrefcount_droot_rec_addr(dblock, 1);
+		numrecs = be16_to_cpu(rblock->bb_numrecs);
+		memcpy(trp, frp, sizeof(*frp) * numrecs);
+	}
+}
+
+/* Flush a realtime reference count btree root out to disk. */
+void
+xfs_iflush_rtrefcount(
+	struct xfs_inode	*ip,
+	struct xfs_dinode	*dip)
+{
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, XFS_DATA_FORK);
+	struct xfs_rtrefcount_root *dfp = XFS_DFORK_PTR(dip, XFS_DATA_FORK);
+
+	ASSERT(ifp->if_broot != NULL);
+	ASSERT(ifp->if_broot_bytes > 0);
+	ASSERT(xfs_rtrefcount_droot_space(ifp->if_broot) <=
+			xfs_inode_fork_size(ip, XFS_DATA_FORK));
+	xfs_rtrefcountbt_to_disk(ip->i_mount, ifp->if_broot,
+			ifp->if_broot_bytes, dfp,
+			XFS_DFORK_SIZE(dip, ip->i_mount, XFS_DATA_FORK));
+}
+
+/*
+ * Create a realtime refcount btree inode.
+ */
+int
+xfs_rtrefcountbt_create(
+	struct xfs_rtgroup	*rtg,
+	struct xfs_inode	*ip,
+	struct xfs_trans	*tp,
+	bool			init)
+{
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, XFS_DATA_FORK);
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_btree_block	*broot;
+
+	ifp->if_format = XFS_DINODE_FMT_META_BTREE;
+	ASSERT(ifp->if_broot_bytes == 0);
+	ASSERT(ifp->if_bytes == 0);
+
+	/* Initialize the empty incore btree root. */
+	broot = xfs_broot_realloc(ifp,
+			xfs_rtrefcount_broot_space_calc(mp, 0, 0));
+	if (broot)
+		xfs_btree_init_block(mp, broot, &xfs_rtrefcountbt_ops, 0, 0,
+				ip->i_ino);
+	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE | XFS_ILOG_DBROOT);
+	return 0;
+}
diff --git a/fs/xfs/libxfs/xfs_rtrefcount_btree.h b/fs/xfs/libxfs/xfs_rtrefcount_btree.h
new file mode 100644
index 000000000000..a99b7a8aec86
--- /dev/null
+++ b/fs/xfs/libxfs/xfs_rtrefcount_btree.h
@@ -0,0 +1,189 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (c) 2021-2024 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#ifndef __XFS_RTREFCOUNT_BTREE_H__
+#define __XFS_RTREFCOUNT_BTREE_H__
+
+struct xfs_buf;
+struct xfs_btree_cur;
+struct xfs_mount;
+struct xbtree_ifakeroot;
+struct xfs_rtgroup;
+
+/* refcounts only exist on crc enabled filesystems */
+#define XFS_RTREFCOUNT_BLOCK_LEN	XFS_BTREE_LBLOCK_CRC_LEN
+
+struct xfs_btree_cur *xfs_rtrefcountbt_init_cursor(struct xfs_trans *tp,
+		struct xfs_rtgroup *rtg);
+struct xfs_btree_cur *xfs_rtrefcountbt_stage_cursor(struct xfs_mount *mp,
+		struct xfs_rtgroup *rtg, struct xfs_inode *ip,
+		struct xbtree_ifakeroot *ifake);
+void xfs_rtrefcountbt_commit_staged_btree(struct xfs_btree_cur *cur,
+		struct xfs_trans *tp);
+unsigned int xfs_rtrefcountbt_maxrecs(struct xfs_mount *mp,
+		unsigned int blocklen, bool leaf);
+void xfs_rtrefcountbt_compute_maxlevels(struct xfs_mount *mp);
+unsigned int xfs_rtrefcountbt_droot_maxrecs(unsigned int blocklen, bool leaf);
+
+/*
+ * Addresses of records, keys, and pointers within an incore rtrefcountbt block.
+ *
+ * (note that some of these may appear unused, but they are used in userspace)
+ */
+static inline struct xfs_refcount_rec *
+xfs_rtrefcount_rec_addr(
+	struct xfs_btree_block	*block,
+	unsigned int		index)
+{
+	return (struct xfs_refcount_rec *)
+		((char *)block + XFS_RTREFCOUNT_BLOCK_LEN +
+		 (index - 1) * sizeof(struct xfs_refcount_rec));
+}
+
+static inline struct xfs_refcount_key *
+xfs_rtrefcount_key_addr(
+	struct xfs_btree_block	*block,
+	unsigned int		index)
+{
+	return (struct xfs_refcount_key *)
+		((char *)block + XFS_RTREFCOUNT_BLOCK_LEN +
+		 (index - 1) * sizeof(struct xfs_refcount_key));
+}
+
+static inline xfs_rtrefcount_ptr_t *
+xfs_rtrefcount_ptr_addr(
+	struct xfs_btree_block	*block,
+	unsigned int		index,
+	unsigned int		maxrecs)
+{
+	return (xfs_rtrefcount_ptr_t *)
+		((char *)block + XFS_RTREFCOUNT_BLOCK_LEN +
+		 maxrecs * sizeof(struct xfs_refcount_key) +
+		 (index - 1) * sizeof(xfs_rtrefcount_ptr_t));
+}
+
+unsigned int xfs_rtrefcountbt_maxlevels_ondisk(void);
+int __init xfs_rtrefcountbt_init_cur_cache(void);
+void xfs_rtrefcountbt_destroy_cur_cache(void);
+
+xfs_filblks_t xfs_rtrefcountbt_calc_reserves(struct xfs_mount *mp);
+unsigned long long xfs_rtrefcountbt_calc_size(struct xfs_mount *mp,
+		unsigned long long len);
+
+/* Addresses of key, pointers, and records within an ondisk rtrefcount block. */
+
+static inline struct xfs_refcount_rec *
+xfs_rtrefcount_droot_rec_addr(
+	struct xfs_rtrefcount_root	*block,
+	unsigned int			index)
+{
+	return (struct xfs_refcount_rec *)
+		((char *)(block + 1) +
+		 (index - 1) * sizeof(struct xfs_refcount_rec));
+}
+
+static inline struct xfs_refcount_key *
+xfs_rtrefcount_droot_key_addr(
+	struct xfs_rtrefcount_root	*block,
+	unsigned int			index)
+{
+	return (struct xfs_refcount_key *)
+		((char *)(block + 1) +
+		 (index - 1) * sizeof(struct xfs_refcount_key));
+}
+
+static inline xfs_rtrefcount_ptr_t *
+xfs_rtrefcount_droot_ptr_addr(
+	struct xfs_rtrefcount_root	*block,
+	unsigned int			index,
+	unsigned int			maxrecs)
+{
+	return (xfs_rtrefcount_ptr_t *)
+		((char *)(block + 1) +
+		 maxrecs * sizeof(struct xfs_refcount_key) +
+		 (index - 1) * sizeof(xfs_rtrefcount_ptr_t));
+}
+
+/*
+ * Address of pointers within the incore btree root.
+ *
+ * These are to be used when we know the size of the block and
+ * we don't have a cursor.
+ */
+static inline xfs_rtrefcount_ptr_t *
+xfs_rtrefcount_broot_ptr_addr(
+	struct xfs_mount	*mp,
+	struct xfs_btree_block	*bb,
+	unsigned int		index,
+	unsigned int		block_size)
+{
+	return xfs_rtrefcount_ptr_addr(bb, index,
+			xfs_rtrefcountbt_maxrecs(mp, block_size, false));
+}
+
+/*
+ * Compute the space required for the incore btree root containing the given
+ * number of records.
+ */
+static inline size_t
+xfs_rtrefcount_broot_space_calc(
+	struct xfs_mount	*mp,
+	unsigned int		level,
+	unsigned int		nrecs)
+{
+	size_t			sz = XFS_RTREFCOUNT_BLOCK_LEN;
+
+	if (level > 0)
+		return sz + nrecs * (sizeof(struct xfs_refcount_key) +
+				     sizeof(xfs_rtrefcount_ptr_t));
+	return sz + nrecs * sizeof(struct xfs_refcount_rec);
+}
+
+/*
+ * Compute the space required for the incore btree root given the ondisk
+ * btree root block.
+ */
+static inline size_t
+xfs_rtrefcount_broot_space(struct xfs_mount *mp, struct xfs_rtrefcount_root *bb)
+{
+	return xfs_rtrefcount_broot_space_calc(mp, be16_to_cpu(bb->bb_level),
+			be16_to_cpu(bb->bb_numrecs));
+}
+
+/* Compute the space required for the ondisk root block. */
+static inline size_t
+xfs_rtrefcount_droot_space_calc(
+	unsigned int		level,
+	unsigned int		nrecs)
+{
+	size_t			sz = sizeof(struct xfs_rtrefcount_root);
+
+	if (level > 0)
+		return sz + nrecs * (sizeof(struct xfs_refcount_key) +
+				     sizeof(xfs_rtrefcount_ptr_t));
+	return sz + nrecs * sizeof(struct xfs_refcount_rec);
+}
+
+/*
+ * Compute the space required for the ondisk root block given an incore root
+ * block.
+ */
+static inline size_t
+xfs_rtrefcount_droot_space(struct xfs_btree_block *bb)
+{
+	return xfs_rtrefcount_droot_space_calc(be16_to_cpu(bb->bb_level),
+			be16_to_cpu(bb->bb_numrecs));
+}
+
+int xfs_iformat_rtrefcount(struct xfs_inode *ip, struct xfs_dinode *dip);
+void xfs_rtrefcountbt_to_disk(struct xfs_mount *mp,
+		struct xfs_btree_block *rblock, int rblocklen,
+		struct xfs_rtrefcount_root *dblock, int dblocklen);
+void xfs_iflush_rtrefcount(struct xfs_inode *ip, struct xfs_dinode *dip);
+
+int xfs_rtrefcountbt_create(struct xfs_rtgroup *rtg, struct xfs_inode *ip,
+		struct xfs_trans *tp, bool init);
+
+#endif	/* __XFS_RTREFCOUNT_BTREE_H__ */
diff --git a/fs/xfs/libxfs/xfs_rtrmap_btree.c b/fs/xfs/libxfs/xfs_rtrmap_btree.c
index b90901e39e92..e4ec36943cb7 100644
--- a/fs/xfs/libxfs/xfs_rtrmap_btree.c
+++ b/fs/xfs/libxfs/xfs_rtrmap_btree.c
@@ -718,6 +718,7 @@ xfs_rtrmapbt_maxrecs(
 unsigned int
 xfs_rtrmapbt_maxlevels_ondisk(void)
 {
+	unsigned long long	max_dblocks;
 	unsigned int		minrecs[2];
 	unsigned int		blocklen;
 
@@ -726,8 +727,20 @@ xfs_rtrmapbt_maxlevels_ondisk(void)
 	minrecs[0] = xfs_rtrmapbt_block_maxrecs(blocklen, true) / 2;
 	minrecs[1] = xfs_rtrmapbt_block_maxrecs(blocklen, false) / 2;
 
-	/* We need at most one record for every block in an rt group. */
-	return xfs_btree_compute_maxlevels(minrecs, XFS_MAX_RGBLOCKS);
+	/*
+	 * Compute the asymptotic maxlevels for an rtrmapbt on any rtreflink fs.
+	 *
+	 * On a reflink filesystem, each block in an rtgroup can have up to
+	 * 2^32 (per the refcount record format) owners, which means that
+	 * theoretically we could face up to 2^64 rmap records.  However, we're
+	 * likely to run out of blocks in the data device long before that
+	 * happens, which means that we must compute the max height based on
+	 * what the btree will look like if it consumes almost all the blocks
+	 * in the data device due to maximal sharing factor.
+	 */
+	max_dblocks = -1U; /* max ag count */
+	max_dblocks *= XFS_MAX_CRC_AG_BLOCKS;
+	return xfs_btree_space_to_height(minrecs, max_dblocks);
 }
 
 int __init
@@ -766,9 +779,20 @@ xfs_rtrmapbt_compute_maxlevels(
 	 * maximum height is constrained by the size of the data device and
 	 * the height required to store one rmap record for each block in an
 	 * rt group.
+	 *
+	 * On a reflink filesystem, each rt block can have up to 2^32 (per the
+	 * refcount record format) owners, which means that theoretically we
+	 * could face up to 2^64 rmap records.  This makes the computation of
+	 * maxlevels based on record count meaningless, so we only consider the
+	 * size of the data device.
 	 */
 	d_maxlevels = xfs_btree_space_to_height(mp->m_rtrmap_mnr,
 				mp->m_sb.sb_dblocks);
+	if (xfs_has_rtreflink(mp)) {
+		mp->m_rtrmap_maxlevels = d_maxlevels + 1;
+		return;
+	}
+
 	r_maxlevels = xfs_btree_compute_maxlevels(mp->m_rtrmap_mnr,
 				mp->m_groups[XG_TYPE_RTG].blocks);
 
diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
index 83fb14b4074c..3dc5f5dba162 100644
--- a/fs/xfs/libxfs/xfs_sb.c
+++ b/fs/xfs/libxfs/xfs_sb.c
@@ -29,6 +29,7 @@
 #include "xfs_exchrange.h"
 #include "xfs_rtgroup.h"
 #include "xfs_rtrmap_btree.h"
+#include "xfs_rtrefcount_btree.h"
 
 /*
  * Physical superblock buffer manipulations. Shared with libxfs in userspace.
@@ -1226,6 +1227,13 @@ xfs_sb_mount_common(
 	mp->m_refc_mnr[0] = mp->m_refc_mxr[0] / 2;
 	mp->m_refc_mnr[1] = mp->m_refc_mxr[1] / 2;
 
+	mp->m_rtrefc_mxr[0] = xfs_rtrefcountbt_maxrecs(mp, sbp->sb_blocksize,
+			true);
+	mp->m_rtrefc_mxr[1] = xfs_rtrefcountbt_maxrecs(mp, sbp->sb_blocksize,
+			false);
+	mp->m_rtrefc_mnr[0] = mp->m_rtrefc_mxr[0] / 2;
+	mp->m_rtrefc_mnr[1] = mp->m_rtrefc_mxr[1] / 2;
+
 	mp->m_bsize = XFS_FSB_TO_BB(mp, 1);
 	mp->m_alloc_set_aside = xfs_alloc_set_aside(mp);
 	mp->m_ag_max_usable = xfs_alloc_ag_max_usable(mp);
diff --git a/fs/xfs/libxfs/xfs_shared.h b/fs/xfs/libxfs/xfs_shared.h
index 960716c387cc..b1e0d9bc1f7d 100644
--- a/fs/xfs/libxfs/xfs_shared.h
+++ b/fs/xfs/libxfs/xfs_shared.h
@@ -42,6 +42,7 @@ extern const struct xfs_buf_ops xfs_rtbitmap_buf_ops;
 extern const struct xfs_buf_ops xfs_rtsummary_buf_ops;
 extern const struct xfs_buf_ops xfs_rtbuf_ops;
 extern const struct xfs_buf_ops xfs_rtsb_buf_ops;
+extern const struct xfs_buf_ops xfs_rtrefcountbt_buf_ops;
 extern const struct xfs_buf_ops xfs_rtrmapbt_buf_ops;
 extern const struct xfs_buf_ops xfs_sb_buf_ops;
 extern const struct xfs_buf_ops xfs_sb_quiet_buf_ops;
@@ -58,6 +59,7 @@ extern const struct xfs_btree_ops xfs_rmapbt_ops;
 extern const struct xfs_btree_ops xfs_rmapbt_mem_ops;
 extern const struct xfs_btree_ops xfs_rtrmapbt_ops;
 extern const struct xfs_btree_ops xfs_rtrmapbt_mem_ops;
+extern const struct xfs_btree_ops xfs_rtrefcountbt_ops;
 
 static inline bool xfs_btree_is_bno(const struct xfs_btree_ops *ops)
 {
@@ -114,6 +116,11 @@ static inline bool xfs_btree_is_rtrmap(const struct xfs_btree_ops *ops)
 	return ops == &xfs_rtrmapbt_ops;
 }
 
+static inline bool xfs_btree_is_rtrefcount(const struct xfs_btree_ops *ops)
+{
+	return ops == &xfs_rtrefcountbt_ops;
+}
+
 /* log size calculation functions */
 int	xfs_log_calc_unit_res(struct xfs_mount *mp, int unit_bytes);
 int	xfs_log_calc_minimum_size(struct xfs_mount *);
diff --git a/fs/xfs/libxfs/xfs_trans_resv.c b/fs/xfs/libxfs/xfs_trans_resv.c
index f3392eb2d7f4..13d00c7166e1 100644
--- a/fs/xfs/libxfs/xfs_trans_resv.c
+++ b/fs/xfs/libxfs/xfs_trans_resv.c
@@ -92,6 +92,14 @@ xfs_refcountbt_block_count(
 	return num_ops * (2 * mp->m_refc_maxlevels - 1);
 }
 
+static unsigned int
+xfs_rtrefcountbt_block_count(
+	struct xfs_mount	*mp,
+	unsigned int		num_ops)
+{
+	return num_ops * (2 * mp->m_rtrefc_maxlevels - 1);
+}
+
 /*
  * Logging inodes is really tricksy. They are logged in memory format,
  * which means that what we write into the log doesn't directly translate into
@@ -259,10 +267,13 @@ xfs_rtalloc_block_count(
  * Compute the log reservation required to handle the refcount update
  * transaction.  Refcount updates are always done via deferred log items.
  *
- * This is calculated as:
+ * This is calculated as the max of:
  * Data device refcount updates (t1):
  *    the agfs of the ags containing the blocks: nr_ops * sector size
  *    the refcount btrees: nr_ops * 1 trees * (2 * max depth - 1) * block size
+ * Realtime refcount updates (t2);
+ *    the rt refcount inode
+ *    the rtrefcount btrees: nr_ops * 1 trees * (2 * max depth - 1) * block size
  */
 static unsigned int
 xfs_calc_refcountbt_reservation(
@@ -270,12 +281,20 @@ xfs_calc_refcountbt_reservation(
 	unsigned int		nr_ops)
 {
 	unsigned int		blksz = XFS_FSB_TO_B(mp, 1);
+	unsigned int		t1, t2 = 0;
 
 	if (!xfs_has_reflink(mp))
 		return 0;
 
-	return xfs_calc_buf_res(nr_ops, mp->m_sb.sb_sectsize) +
-	       xfs_calc_buf_res(xfs_refcountbt_block_count(mp, nr_ops), blksz);
+	t1 = xfs_calc_buf_res(nr_ops, mp->m_sb.sb_sectsize) +
+	     xfs_calc_buf_res(xfs_refcountbt_block_count(mp, nr_ops), blksz);
+
+	if (xfs_has_realtime(mp))
+		t2 = xfs_calc_inode_res(mp, 1) +
+		     xfs_calc_buf_res(xfs_rtrefcountbt_block_count(mp, nr_ops),
+				     blksz);
+
+	return max(t1, t2);
 }
 
 /*
diff --git a/fs/xfs/scrub/agheader_repair.c b/fs/xfs/scrub/agheader_repair.c
index b45d2b32051a..cd6f0223879f 100644
--- a/fs/xfs/scrub/agheader_repair.c
+++ b/fs/xfs/scrub/agheader_repair.c
@@ -647,7 +647,7 @@ xrep_agfl_fill(
 	xfs_agblock_t		agbno = start;
 	int			error;
 
-	trace_xrep_agfl_insert(sc->sa.pag, agbno, len);
+	trace_xrep_agfl_insert(pag_group(sc->sa.pag), agbno, len);
 
 	while (agbno < start + len && af->fl_off < af->flcount)
 		af->agfl_bno[af->fl_off++] = cpu_to_be32(agbno++);
diff --git a/fs/xfs/scrub/bmap.c b/fs/xfs/scrub/bmap.c
index f6077b0cba8a..66da7d4d56ba 100644
--- a/fs/xfs/scrub/bmap.c
+++ b/fs/xfs/scrub/bmap.c
@@ -347,13 +347,31 @@ xchk_bmap_rt_iextent_xref(
 		goto out_cur;
 
 	rgbno = xfs_rtb_to_rgbno(info->sc->mp, irec->br_startblock);
-	xchk_bmap_xref_rmap(info, irec, rgbno);
-
-	xfs_rmap_ino_owner(&oinfo, info->sc->ip->i_ino, info->whichfork,
-			irec->br_startoff);
-	xchk_xref_is_only_rt_owned_by(info->sc, rgbno,
-			irec->br_blockcount, &oinfo);
 
+	switch (info->whichfork) {
+	case XFS_DATA_FORK:
+		xchk_bmap_xref_rmap(info, irec, rgbno);
+		if (!xfs_is_reflink_inode(info->sc->ip)) {
+			xfs_rmap_ino_owner(&oinfo, info->sc->ip->i_ino,
+					info->whichfork, irec->br_startoff);
+			xchk_xref_is_only_rt_owned_by(info->sc, rgbno,
+					irec->br_blockcount, &oinfo);
+			xchk_xref_is_not_rt_shared(info->sc, rgbno,
+					irec->br_blockcount);
+		}
+		xchk_xref_is_not_rt_cow_staging(info->sc, rgbno,
+				irec->br_blockcount);
+		break;
+	case XFS_COW_FORK:
+		xchk_bmap_xref_rmap_cow(info, irec, rgbno);
+		xchk_xref_is_only_rt_owned_by(info->sc, rgbno,
+				irec->br_blockcount, &XFS_RMAP_OINFO_COW);
+		xchk_xref_is_rt_cow_staging(info->sc, rgbno,
+				irec->br_blockcount);
+		xchk_xref_is_not_rt_shared(info->sc, rgbno,
+				irec->br_blockcount);
+		break;
+	}
 out_cur:
 	xchk_rtgroup_btcur_free(&info->sc->sr);
 out_free:
diff --git a/fs/xfs/scrub/bmap_repair.c b/fs/xfs/scrub/bmap_repair.c
index fd64bdf4e138..1084213b8e9b 100644
--- a/fs/xfs/scrub/bmap_repair.c
+++ b/fs/xfs/scrub/bmap_repair.c
@@ -101,14 +101,21 @@ xrep_bmap_discover_shared(
 	xfs_filblks_t		blockcount)
 {
 	struct xfs_scrub	*sc = rb->sc;
+	struct xfs_btree_cur	*cur;
 	xfs_agblock_t		agbno;
 	xfs_agblock_t		fbno;
 	xfs_extlen_t		flen;
 	int			error;
 
-	agbno = XFS_FSB_TO_AGBNO(sc->mp, startblock);
-	error = xfs_refcount_find_shared(sc->sa.refc_cur, agbno, blockcount,
-			&fbno, &flen, false);
+	if (XFS_IS_REALTIME_INODE(sc->ip)) {
+		agbno = xfs_rtb_to_rgbno(sc->mp, startblock);
+		cur = sc->sr.refc_cur;
+	} else {
+		agbno = XFS_FSB_TO_AGBNO(sc->mp, startblock);
+		cur = sc->sa.refc_cur;
+	}
+	error = xfs_refcount_find_shared(cur, agbno, blockcount, &fbno, &flen,
+			false);
 	if (error)
 		return error;
 
@@ -450,7 +457,9 @@ xrep_bmap_scan_rtgroup(
 		return 0;
 
 	error = xrep_rtgroup_init(sc, rtg, &sc->sr,
-			XFS_RTGLOCK_RMAP | XFS_RTGLOCK_BITMAP_SHARED);
+			XFS_RTGLOCK_RMAP |
+			XFS_RTGLOCK_REFCOUNT |
+			XFS_RTGLOCK_BITMAP_SHARED);
 	if (error)
 		return error;
 
@@ -903,10 +912,6 @@ xrep_bmap_init_reflink_scan(
 	if (whichfork != XFS_DATA_FORK)
 		return RLS_IRRELEVANT;
 
-	/* cannot share realtime extents */
-	if (XFS_IS_REALTIME_INODE(sc->ip))
-		return RLS_IRRELEVANT;
-
 	return RLS_UNKNOWN;
 }
 
diff --git a/fs/xfs/scrub/common.c b/fs/xfs/scrub/common.c
index 06cb61e63498..28ad341df8ee 100644
--- a/fs/xfs/scrub/common.c
+++ b/fs/xfs/scrub/common.c
@@ -37,6 +37,7 @@
 #include "xfs_rtgroup.h"
 #include "xfs_rtrmap_btree.h"
 #include "xfs_bmap_util.h"
+#include "xfs_rtrefcount_btree.h"
 #include "scrub/scrub.h"
 #include "scrub/common.h"
 #include "scrub/trace.h"
@@ -797,6 +798,9 @@ xchk_rtgroup_lock(
 	if (xfs_has_rtrmapbt(sc->mp) && (rtglock_flags & XFS_RTGLOCK_RMAP))
 		sr->rmap_cur = xfs_rtrmapbt_init_cursor(sc->tp, sr->rtg);
 
+	if (xfs_has_rtreflink(sc->mp) && (rtglock_flags & XFS_RTGLOCK_REFCOUNT))
+		sr->refc_cur = xfs_rtrefcountbt_init_cursor(sc->tp, sr->rtg);
+
 	return 0;
 }
 
@@ -811,7 +815,10 @@ xchk_rtgroup_btcur_free(
 {
 	if (sr->rmap_cur)
 		xfs_btree_del_cursor(sr->rmap_cur, XFS_BTREE_ERROR);
+	if (sr->refc_cur)
+		xfs_btree_del_cursor(sr->refc_cur, XFS_BTREE_ERROR);
 
+	sr->refc_cur = NULL;
 	sr->rmap_cur = NULL;
 }
 
@@ -1687,6 +1694,9 @@ xchk_meta_btree_count_blocks(
 	case XFS_METAFILE_RTRMAP:
 		cur = xfs_rtrmapbt_init_cursor(sc->tp, sc->sr.rtg);
 		break;
+	case XFS_METAFILE_RTREFCOUNT:
+		cur = xfs_rtrefcountbt_init_cursor(sc->tp, sc->sr.rtg);
+		break;
 	default:
 		ASSERT(0);
 		return -EFSCORRUPTED;
diff --git a/fs/xfs/scrub/common.h b/fs/xfs/scrub/common.h
index 50ac6cca18fe..bdcd40f0ec74 100644
--- a/fs/xfs/scrub/common.h
+++ b/fs/xfs/scrub/common.h
@@ -82,11 +82,13 @@ int xchk_setup_rtbitmap(struct xfs_scrub *sc);
 int xchk_setup_rtsummary(struct xfs_scrub *sc);
 int xchk_setup_rgsuperblock(struct xfs_scrub *sc);
 int xchk_setup_rtrmapbt(struct xfs_scrub *sc);
+int xchk_setup_rtrefcountbt(struct xfs_scrub *sc);
 #else
 # define xchk_setup_rtbitmap		xchk_setup_nothing
 # define xchk_setup_rtsummary		xchk_setup_nothing
 # define xchk_setup_rgsuperblock	xchk_setup_nothing
 # define xchk_setup_rtrmapbt		xchk_setup_nothing
+# define xchk_setup_rtrefcountbt	xchk_setup_nothing
 #endif
 #ifdef CONFIG_XFS_QUOTA
 int xchk_ino_dqattach(struct xfs_scrub *sc);
@@ -129,7 +131,8 @@ xchk_ag_init_existing(
 
 /* All the locks we need to check an rtgroup. */
 #define XCHK_RTGLOCK_ALL	(XFS_RTGLOCK_BITMAP | \
-				 XFS_RTGLOCK_RMAP)
+				 XFS_RTGLOCK_RMAP | \
+				 XFS_RTGLOCK_REFCOUNT)
 
 int xchk_rtgroup_init(struct xfs_scrub *sc, xfs_rgnumber_t rgno,
 		struct xchk_rt *sr);
diff --git a/fs/xfs/scrub/cow_repair.c b/fs/xfs/scrub/cow_repair.c
index 5b6194cef3e5..38a246b8bf11 100644
--- a/fs/xfs/scrub/cow_repair.c
+++ b/fs/xfs/scrub/cow_repair.c
@@ -26,6 +26,9 @@
 #include "xfs_errortag.h"
 #include "xfs_icache.h"
 #include "xfs_refcount_btree.h"
+#include "xfs_rtalloc.h"
+#include "xfs_rtbitmap.h"
+#include "xfs_rtgroup.h"
 #include "scrub/xfs_scrub.h"
 #include "scrub/scrub.h"
 #include "scrub/common.h"
@@ -34,6 +37,7 @@
 #include "scrub/bitmap.h"
 #include "scrub/off_bitmap.h"
 #include "scrub/fsb_bitmap.h"
+#include "scrub/rtb_bitmap.h"
 #include "scrub/reap.h"
 
 /*
@@ -61,7 +65,10 @@ struct xrep_cow {
 	struct xoff_bitmap	bad_fileoffs;
 
 	/* Bitmap of fsblocks that were removed from the CoW fork. */
-	struct xfsb_bitmap	old_cowfork_fsblocks;
+	union {
+		struct xfsb_bitmap	old_cowfork_fsblocks;
+		struct xrtb_bitmap	old_cowfork_rtblocks;
+	};
 
 	/* CoW fork mappings used to scan for bad CoW staging extents. */
 	struct xfs_bmbt_irec	irec;
@@ -145,8 +152,7 @@ xrep_cow_mark_shared_staging(
 	xrep_cow_trim_refcount(xc, &rrec, rec);
 
 	return xrep_cow_mark_file_range(xc,
-			xfs_agbno_to_fsb(to_perag(cur->bc_group),
-				rrec.rc_startblock),
+			xfs_gbno_to_fsb(cur->bc_group, rrec.rc_startblock),
 			rrec.rc_blockcount);
 }
 
@@ -177,9 +183,8 @@ xrep_cow_mark_missing_staging(
 	if (xc->next_bno >= rrec.rc_startblock)
 		goto next;
 
-
 	error = xrep_cow_mark_file_range(xc,
-			xfs_agbno_to_fsb(to_perag(cur->bc_group), xc->next_bno),
+			xfs_gbno_to_fsb(cur->bc_group, xc->next_bno),
 			rrec.rc_startblock - xc->next_bno);
 	if (error)
 		return error;
@@ -222,8 +227,7 @@ xrep_cow_mark_missing_staging_rmap(
 	}
 
 	return xrep_cow_mark_file_range(xc,
-			xfs_agbno_to_fsb(to_perag(cur->bc_group), rec_bno),
-			rec_len);
+			xfs_gbno_to_fsb(cur->bc_group, rec_bno), rec_len);
 }
 
 /*
@@ -311,6 +315,92 @@ out_pag:
 }
 
 /*
+ * Find any part of the CoW fork mapping that isn't a single-owner CoW staging
+ * extent and mark the corresponding part of the file range in the bitmap.
+ */
+STATIC int
+xrep_cow_find_bad_rt(
+	struct xrep_cow			*xc)
+{
+	struct xfs_refcount_irec	rc_low = { 0 };
+	struct xfs_refcount_irec	rc_high = { 0 };
+	struct xfs_rmap_irec		rm_low = { 0 };
+	struct xfs_rmap_irec		rm_high = { 0 };
+	struct xfs_scrub		*sc = xc->sc;
+	struct xfs_rtgroup		*rtg;
+	int				error = 0;
+
+	xc->irec_startbno = xfs_rtb_to_rgbno(sc->mp, xc->irec.br_startblock);
+
+	rtg = xfs_rtgroup_get(sc->mp,
+			xfs_rtb_to_rgno(sc->mp, xc->irec.br_startblock));
+	if (!rtg)
+		return -EFSCORRUPTED;
+
+	error = xrep_rtgroup_init(sc, rtg, &sc->sr,
+			XFS_RTGLOCK_RMAP | XFS_RTGLOCK_REFCOUNT);
+	if (error)
+		goto out_rtg;
+
+	/* Mark any CoW fork extents that are shared. */
+	rc_low.rc_startblock = xc->irec_startbno;
+	rc_high.rc_startblock = xc->irec_startbno + xc->irec.br_blockcount - 1;
+	rc_low.rc_domain = rc_high.rc_domain = XFS_REFC_DOMAIN_SHARED;
+	error = xfs_refcount_query_range(sc->sr.refc_cur, &rc_low, &rc_high,
+			xrep_cow_mark_shared_staging, xc);
+	if (error)
+		goto out_sr;
+
+	/* Make sure there are CoW staging extents for the whole mapping. */
+	rc_low.rc_startblock = xc->irec_startbno;
+	rc_high.rc_startblock = xc->irec_startbno + xc->irec.br_blockcount - 1;
+	rc_low.rc_domain = rc_high.rc_domain = XFS_REFC_DOMAIN_COW;
+	xc->next_bno = xc->irec_startbno;
+	error = xfs_refcount_query_range(sc->sr.refc_cur, &rc_low, &rc_high,
+			xrep_cow_mark_missing_staging, xc);
+	if (error)
+		goto out_sr;
+
+	if (xc->next_bno < xc->irec_startbno + xc->irec.br_blockcount) {
+		error = xrep_cow_mark_file_range(xc,
+				xfs_rgbno_to_rtb(rtg, xc->next_bno),
+				xc->irec_startbno + xc->irec.br_blockcount -
+				xc->next_bno);
+		if (error)
+			goto out_sr;
+	}
+
+	/* Mark any area has an rmap that isn't a COW staging extent. */
+	rm_low.rm_startblock = xc->irec_startbno;
+	memset(&rm_high, 0xFF, sizeof(rm_high));
+	rm_high.rm_startblock = xc->irec_startbno + xc->irec.br_blockcount - 1;
+	error = xfs_rmap_query_range(sc->sr.rmap_cur, &rm_low, &rm_high,
+			xrep_cow_mark_missing_staging_rmap, xc);
+	if (error)
+		goto out_sr;
+
+	/*
+	 * If userspace is forcing us to rebuild the CoW fork or someone
+	 * turned on the debugging knob, replace everything in the
+	 * CoW fork and then scan for staging extents in the refcountbt.
+	 */
+	if ((sc->sm->sm_flags & XFS_SCRUB_IFLAG_FORCE_REBUILD) ||
+	    XFS_TEST_ERROR(false, sc->mp, XFS_ERRTAG_FORCE_SCRUB_REPAIR)) {
+		error = xrep_cow_mark_file_range(xc, xc->irec.br_startblock,
+				xc->irec.br_blockcount);
+		if (error)
+			goto out_rtg;
+	}
+
+out_sr:
+	xchk_rtgroup_btcur_free(&sc->sr);
+	xchk_rtgroup_free(sc, &sc->sr);
+out_rtg:
+	xfs_rtgroup_put(rtg);
+	return error;
+}
+
+/*
  * Allocate a replacement CoW staging extent of up to the given number of
  * blocks, and fill out the mapping.
  */
@@ -343,7 +433,7 @@ xrep_cow_alloc(
 	if (args.fsbno == NULLFSBLOCK)
 		return -ENOSPC;
 
-	xfs_refcount_alloc_cow_extent(sc->tp, args.fsbno, args.len);
+	xfs_refcount_alloc_cow_extent(sc->tp, false, args.fsbno, args.len);
 
 	repl->fsbno = args.fsbno;
 	repl->len = args.len;
@@ -351,6 +441,32 @@ xrep_cow_alloc(
 }
 
 /*
+ * Allocate a replacement rt CoW staging extent of up to the given number of
+ * blocks, and fill out the mapping.
+ */
+STATIC int
+xrep_cow_alloc_rt(
+	struct xfs_scrub	*sc,
+	xfs_extlen_t		maxlen,
+	struct xrep_cow_extent	*repl)
+{
+	xfs_rtxlen_t		maxrtx = xfs_rtb_to_rtx(sc->mp, maxlen);
+	int			error;
+
+	error = xfs_trans_reserve_more(sc->tp, 0, maxrtx);
+	if (error)
+		return error;
+
+	error = xfs_rtallocate_rtgs(sc->tp, NULLRTBLOCK, 1, maxrtx, 1, false,
+			false, &repl->fsbno, &repl->len);
+	if (error)
+		return error;
+
+	xfs_refcount_alloc_cow_extent(sc->tp, true, repl->fsbno, repl->len);
+	return 0;
+}
+
+/*
  * Look up the current CoW fork mapping so that we only allocate enough to
  * replace a single mapping.  If we don't find a mapping that covers the start
  * of the file range, or we find a delalloc or written extent, something is
@@ -467,7 +583,10 @@ xrep_cow_replace_range(
 	 */
 	alloc_len = min_t(xfs_fileoff_t, XFS_MAX_BMBT_EXTLEN,
 			  nextoff - startoff);
-	error = xrep_cow_alloc(sc, alloc_len, &repl);
+	if (XFS_IS_REALTIME_INODE(sc->ip))
+		error = xrep_cow_alloc_rt(sc, alloc_len, &repl);
+	else
+		error = xrep_cow_alloc(sc, alloc_len, &repl);
 	if (error)
 		return error;
 
@@ -483,8 +602,12 @@ xrep_cow_replace_range(
 		return error;
 
 	/* Note the old CoW staging extents; we'll reap them all later. */
-	error = xfsb_bitmap_set(&xc->old_cowfork_fsblocks, got.br_startblock,
-			repl.len);
+	if (XFS_IS_REALTIME_INODE(sc->ip))
+		error = xrtb_bitmap_set(&xc->old_cowfork_rtblocks,
+				got.br_startblock, repl.len);
+	else
+		error = xfsb_bitmap_set(&xc->old_cowfork_fsblocks,
+				got.br_startblock, repl.len);
 	if (error)
 		return error;
 
@@ -540,8 +663,16 @@ xrep_bmap_cow(
 	if (!ifp)
 		return 0;
 
-	/* realtime files aren't supported yet */
-	if (XFS_IS_REALTIME_INODE(sc->ip))
+	/*
+	 * Realtime files with large extent sizes are not supported because
+	 * we could encounter an CoW mapping that has been partially written
+	 * out *and* requires replacement, and there's no solution to that.
+	 */
+	if (xfs_inode_has_bigrtalloc(sc->ip))
+		return -EOPNOTSUPP;
+
+	/* Metadata inodes aren't supposed to have data on the rt volume. */
+	if (xfs_is_metadir_inode(sc->ip) && XFS_IS_REALTIME_INODE(sc->ip))
 		return -EOPNOTSUPP;
 
 	/*
@@ -562,7 +693,10 @@ xrep_bmap_cow(
 
 	xc->sc = sc;
 	xoff_bitmap_init(&xc->bad_fileoffs);
-	xfsb_bitmap_init(&xc->old_cowfork_fsblocks);
+	if (XFS_IS_REALTIME_INODE(sc->ip))
+		xrtb_bitmap_init(&xc->old_cowfork_rtblocks);
+	else
+		xfsb_bitmap_init(&xc->old_cowfork_fsblocks);
 
 	for_each_xfs_iext(ifp, &icur, &xc->irec) {
 		if (xchk_should_terminate(sc, &error))
@@ -585,7 +719,10 @@ xrep_bmap_cow(
 		if (xfs_bmap_is_written_extent(&xc->irec))
 			continue;
 
-		error = xrep_cow_find_bad(xc);
+		if (XFS_IS_REALTIME_INODE(sc->ip))
+			error = xrep_cow_find_bad_rt(xc);
+		else
+			error = xrep_cow_find_bad(xc);
 		if (error)
 			goto out_bitmap;
 	}
@@ -600,13 +737,20 @@ xrep_bmap_cow(
 	 * by the refcount btree, not the inode, so it is correct to treat them
 	 * like inode metadata.
 	 */
-	error = xrep_reap_fsblocks(sc, &xc->old_cowfork_fsblocks,
-			&XFS_RMAP_OINFO_COW);
+	if (XFS_IS_REALTIME_INODE(sc->ip))
+		error = xrep_reap_rtblocks(sc, &xc->old_cowfork_rtblocks,
+				&XFS_RMAP_OINFO_COW);
+	else
+		error = xrep_reap_fsblocks(sc, &xc->old_cowfork_fsblocks,
+				&XFS_RMAP_OINFO_COW);
 	if (error)
 		goto out_bitmap;
 
 out_bitmap:
-	xfsb_bitmap_destroy(&xc->old_cowfork_fsblocks);
+	if (XFS_IS_REALTIME_INODE(sc->ip))
+		xrtb_bitmap_destroy(&xc->old_cowfork_rtblocks);
+	else
+		xfsb_bitmap_destroy(&xc->old_cowfork_fsblocks);
 	xoff_bitmap_destroy(&xc->bad_fileoffs);
 	kfree(xc);
 	return error;
diff --git a/fs/xfs/scrub/health.c b/fs/xfs/scrub/health.c
index bcc4244e3b55..3c0f25098b69 100644
--- a/fs/xfs/scrub/health.c
+++ b/fs/xfs/scrub/health.c
@@ -115,6 +115,7 @@ static const struct xchk_health_map type_to_health_flag[XFS_SCRUB_TYPE_NR] = {
 	[XFS_SCRUB_TYPE_METAPATH]	= { XHG_FS,  XFS_SICK_FS_METAPATH },
 	[XFS_SCRUB_TYPE_RGSUPER]	= { XHG_RTGROUP, XFS_SICK_RG_SUPER },
 	[XFS_SCRUB_TYPE_RTRMAPBT]	= { XHG_RTGROUP, XFS_SICK_RG_RMAPBT },
+	[XFS_SCRUB_TYPE_RTREFCBT]	= { XHG_RTGROUP, XFS_SICK_RG_REFCNTBT },
 };
 
 /* Return the health status mask for this scrub type. */
diff --git a/fs/xfs/scrub/inode.c b/fs/xfs/scrub/inode.c
index 8e702121dc86..db6edd5a5fe5 100644
--- a/fs/xfs/scrub/inode.c
+++ b/fs/xfs/scrub/inode.c
@@ -260,12 +260,7 @@ xchk_inode_extsize(
 		xchk_ino_set_warning(sc, ino);
 }
 
-/*
- * Validate di_cowextsize hint.
- *
- * The rules are documented at xfs_ioctl_setattr_check_cowextsize().
- * These functions must be kept in sync with each other.
- */
+/* Validate di_cowextsize hint. */
 STATIC void
 xchk_inode_cowextsize(
 	struct xfs_scrub	*sc,
@@ -276,12 +271,25 @@ xchk_inode_cowextsize(
 	uint64_t		flags2)
 {
 	xfs_failaddr_t		fa;
+	uint32_t		value = be32_to_cpu(dip->di_cowextsize);
 
-	fa = xfs_inode_validate_cowextsize(sc->mp,
-			be32_to_cpu(dip->di_cowextsize), mode, flags,
-			flags2);
+	fa = xfs_inode_validate_cowextsize(sc->mp, value, mode, flags, flags2);
 	if (fa)
 		xchk_ino_set_corrupt(sc, ino);
+
+	/*
+	 * XFS allows a sysadmin to change the rt extent size when adding a rt
+	 * section to a filesystem after formatting.  If there are any
+	 * directories with cowextsize and rtinherit set, the hint could become
+	 * misaligned with the new rextsize.  The verifier doesn't check this,
+	 * because we allow rtinherit directories even without an rt device.
+	 * Flag this as an administrative warning since we will clean this up
+	 * eventually.
+	 */
+	if ((flags & XFS_DIFLAG_RTINHERIT) &&
+	    (flags2 & XFS_DIFLAG2_COWEXTSIZE) &&
+	    value % sc->mp->m_sb.sb_rextsize > 0)
+		xchk_ino_set_warning(sc, ino);
 }
 
 /* Make sure the di_flags make sense for the inode. */
@@ -360,8 +368,9 @@ xchk_inode_flags2(
 	if ((flags2 & XFS_DIFLAG2_REFLINK) && !S_ISREG(mode))
 		goto bad;
 
-	/* realtime and reflink make no sense, currently */
-	if ((flags & XFS_DIFLAG_REALTIME) && (flags2 & XFS_DIFLAG2_REFLINK))
+	/* realtime and reflink don't always go together */
+	if ((flags & XFS_DIFLAG_REALTIME) && (flags2 & XFS_DIFLAG2_REFLINK) &&
+	    !xfs_has_rtreflink(mp))
 		goto bad;
 
 	/* no bigtime iflag without the bigtime feature */
diff --git a/fs/xfs/scrub/inode_repair.c b/fs/xfs/scrub/inode_repair.c
index d7e3f033b160..2f641b6d663e 100644
--- a/fs/xfs/scrub/inode_repair.c
+++ b/fs/xfs/scrub/inode_repair.c
@@ -40,6 +40,7 @@
 #include "xfs_symlink_remote.h"
 #include "xfs_rtgroup.h"
 #include "xfs_rtrmap_btree.h"
+#include "xfs_rtrefcount_btree.h"
 #include "scrub/xfs_scrub.h"
 #include "scrub/scrub.h"
 #include "scrub/common.h"
@@ -564,8 +565,6 @@ xrep_dinode_flags(
 		flags2 |= XFS_DIFLAG2_REFLINK;
 	else
 		flags2 &= ~(XFS_DIFLAG2_REFLINK | XFS_DIFLAG2_COWEXTSIZE);
-	if (flags & XFS_DIFLAG_REALTIME)
-		flags2 &= ~XFS_DIFLAG2_REFLINK;
 	if (!xfs_has_bigtime(mp))
 		flags2 &= ~XFS_DIFLAG2_BIGTIME;
 	if (!xfs_has_large_extent_counts(mp))
@@ -972,6 +971,34 @@ xrep_dinode_bad_rtrmapbt_fork(
 	return false;
 }
 
+/* Return true if this refcount-format ifork looks like garbage. */
+STATIC bool
+xrep_dinode_bad_rtrefcountbt_fork(
+	struct xfs_scrub	*sc,
+	struct xfs_dinode	*dip,
+	unsigned int		dfork_size)
+{
+	struct xfs_rtrefcount_root *dfp;
+	unsigned int		nrecs;
+	unsigned int		level;
+
+	if (dfork_size < sizeof(struct xfs_rtrefcount_root))
+		return true;
+
+	dfp = XFS_DFORK_PTR(dip, XFS_DATA_FORK);
+	nrecs = be16_to_cpu(dfp->bb_numrecs);
+	level = be16_to_cpu(dfp->bb_level);
+
+	if (level > sc->mp->m_rtrefc_maxlevels)
+		return true;
+	if (xfs_rtrefcount_droot_space_calc(level, nrecs) > dfork_size)
+		return true;
+	if (level > 0 && nrecs == 0)
+		return true;
+
+	return false;
+}
+
 /* Check a metadata-btree fork. */
 STATIC bool
 xrep_dinode_bad_metabt_fork(
@@ -986,6 +1013,8 @@ xrep_dinode_bad_metabt_fork(
 	switch (be16_to_cpu(dip->di_metatype)) {
 	case XFS_METAFILE_RTRMAP:
 		return xrep_dinode_bad_rtrmapbt_fork(sc, dip, dfork_size);
+	case XFS_METAFILE_RTREFCOUNT:
+		return xrep_dinode_bad_rtrefcountbt_fork(sc, dip, dfork_size);
 	default:
 		return true;
 	}
@@ -1251,6 +1280,7 @@ xrep_dinode_ensure_forkoff(
 {
 	struct xfs_bmdr_block	*bmdr;
 	struct xfs_rtrmap_root	*rmdr;
+	struct xfs_rtrefcount_root *rcdr;
 	struct xfs_scrub	*sc = ri->sc;
 	xfs_extnum_t		attr_extents, data_extents;
 	size_t			bmdr_minsz = xfs_bmdr_space_calc(1);
@@ -1363,6 +1393,10 @@ xrep_dinode_ensure_forkoff(
 			rmdr = XFS_DFORK_PTR(dip, XFS_DATA_FORK);
 			dfork_min = xfs_rtrmap_broot_space(sc->mp, rmdr);
 			break;
+		case XFS_METAFILE_RTREFCOUNT:
+			rcdr = XFS_DFORK_PTR(dip, XFS_DATA_FORK);
+			dfork_min = xfs_rtrefcount_broot_space(sc->mp, rcdr);
+			break;
 		default:
 			dfork_min = 0;
 			break;
@@ -1790,10 +1824,6 @@ xrep_inode_flags(
 	/* DAX only applies to files and dirs. */
 	if (!(S_ISREG(mode) || S_ISDIR(mode)))
 		sc->ip->i_diflags2 &= ~XFS_DIFLAG2_DAX;
-
-	/* No reflink files on the realtime device. */
-	if (sc->ip->i_diflags & XFS_DIFLAG_REALTIME)
-		sc->ip->i_diflags2 &= ~XFS_DIFLAG2_REFLINK;
 }
 
 /*
@@ -1909,6 +1939,20 @@ xrep_inode_pptr(
 			sizeof(struct xfs_attr_sf_hdr), true);
 }
 
+/* Fix COW extent size hint problems. */
+STATIC void
+xrep_inode_cowextsize(
+	struct xfs_scrub	*sc)
+{
+	/* Fix misaligned CoW extent size hints on a directory. */
+	if ((sc->ip->i_diflags & XFS_DIFLAG_RTINHERIT) &&
+	    (sc->ip->i_diflags2 & XFS_DIFLAG2_COWEXTSIZE) &&
+	    sc->ip->i_extsize % sc->mp->m_sb.sb_rextsize > 0) {
+		sc->ip->i_cowextsize = 0;
+		sc->ip->i_diflags2 &= ~XFS_DIFLAG2_COWEXTSIZE;
+	}
+}
+
 /* Fix any irregularities in an inode that the verifiers don't catch. */
 STATIC int
 xrep_inode_problems(
@@ -1932,6 +1976,7 @@ xrep_inode_problems(
 	if (S_ISDIR(VFS_I(sc->ip)->i_mode))
 		xrep_inode_dir_size(sc);
 	xrep_inode_extsize(sc);
+	xrep_inode_cowextsize(sc);
 
 	trace_xrep_inode_fixed(sc);
 	xfs_trans_log_inode(sc->tp, sc->ip, XFS_ILOG_CORE);
diff --git a/fs/xfs/scrub/metapath.c b/fs/xfs/scrub/metapath.c
index 74d71373e7ed..e21c16fbd15d 100644
--- a/fs/xfs/scrub/metapath.c
+++ b/fs/xfs/scrub/metapath.c
@@ -22,6 +22,7 @@
 #include "xfs_attr.h"
 #include "xfs_rtgroup.h"
 #include "xfs_rtrmap_btree.h"
+#include "xfs_rtrefcount_btree.h"
 #include "scrub/scrub.h"
 #include "scrub/common.h"
 #include "scrub/trace.h"
@@ -249,6 +250,8 @@ xchk_setup_metapath(
 		return xchk_setup_metapath_dqinode(sc, XFS_DQTYPE_PROJ);
 	case XFS_SCRUB_METAPATH_RTRMAPBT:
 		return xchk_setup_metapath_rtginode(sc, XFS_RTGI_RMAP);
+	case XFS_SCRUB_METAPATH_RTREFCOUNTBT:
+		return xchk_setup_metapath_rtginode(sc, XFS_RTGI_REFCOUNT);
 	default:
 		return -ENOENT;
 	}
diff --git a/fs/xfs/scrub/quota.c b/fs/xfs/scrub/quota.c
index 183d531875ea..58d6d4ed2853 100644
--- a/fs/xfs/scrub/quota.c
+++ b/fs/xfs/scrub/quota.c
@@ -212,12 +212,18 @@ xchk_quota_item(
 		if (mp->m_sb.sb_dblocks < dq->q_blk.count)
 			xchk_fblock_set_warning(sc, XFS_DATA_FORK,
 					offset);
+		if (mp->m_sb.sb_rblocks < dq->q_rtb.count)
+			xchk_fblock_set_warning(sc, XFS_DATA_FORK,
+					offset);
 	} else {
 		if (mp->m_sb.sb_dblocks < dq->q_blk.count)
 			xchk_fblock_set_corrupt(sc, XFS_DATA_FORK,
 					offset);
+		if (mp->m_sb.sb_rblocks < dq->q_rtb.count)
+			xchk_fblock_set_corrupt(sc, XFS_DATA_FORK,
+					offset);
 	}
-	if (dq->q_ino.count > fs_icount || dq->q_rtb.count > mp->m_sb.sb_rblocks)
+	if (dq->q_ino.count > fs_icount)
 		xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, offset);
 
 	/*
diff --git a/fs/xfs/scrub/quota_repair.c b/fs/xfs/scrub/quota_repair.c
index cd51f10f2920..8f4c8d41f308 100644
--- a/fs/xfs/scrub/quota_repair.c
+++ b/fs/xfs/scrub/quota_repair.c
@@ -233,7 +233,7 @@ xrep_quota_item(
 		rqi->need_quotacheck = true;
 		dirty = true;
 	}
-	if (dq->q_rtb.count > mp->m_sb.sb_rblocks) {
+	if (!xfs_has_reflink(mp) && dq->q_rtb.count > mp->m_sb.sb_rblocks) {
 		dq->q_rtb.reserved -= dq->q_rtb.count;
 		dq->q_rtb.reserved += mp->m_sb.sb_rblocks;
 		dq->q_rtb.count = mp->m_sb.sb_rblocks;
diff --git a/fs/xfs/scrub/reap.c b/fs/xfs/scrub/reap.c
index 4d7f1b82dc55..b32fb233cf84 100644
--- a/fs/xfs/scrub/reap.c
+++ b/fs/xfs/scrub/reap.c
@@ -34,6 +34,8 @@
 #include "xfs_attr_remote.h"
 #include "xfs_defer.h"
 #include "xfs_metafile.h"
+#include "xfs_rtgroup.h"
+#include "xfs_rtrmap_btree.h"
 #include "scrub/scrub.h"
 #include "scrub/common.h"
 #include "scrub/trace.h"
@@ -41,6 +43,7 @@
 #include "scrub/bitmap.h"
 #include "scrub/agb_bitmap.h"
 #include "scrub/fsb_bitmap.h"
+#include "scrub/rtb_bitmap.h"
 #include "scrub/reap.h"
 
 /*
@@ -311,7 +314,7 @@ xreap_agextent_binval(
 	}
 
 out:
-	trace_xreap_agextent_binval(sc->sa.pag, agbno, *aglenp);
+	trace_xreap_agextent_binval(pag_group(sc->sa.pag), agbno, *aglenp);
 }
 
 /*
@@ -370,7 +373,8 @@ xreap_agextent_select(
 
 out_found:
 	*aglenp = len;
-	trace_xreap_agextent_select(sc->sa.pag, agbno, len, *crosslinked);
+	trace_xreap_agextent_select(pag_group(sc->sa.pag), agbno, len,
+			*crosslinked);
 out_cur:
 	xfs_btree_del_cursor(cur, error);
 	return error;
@@ -409,7 +413,8 @@ xreap_agextent_iter(
 	 * to run xfs_repair.
 	 */
 	if (crosslinked) {
-		trace_xreap_dispose_unmap_extent(sc->sa.pag, agbno, *aglenp);
+		trace_xreap_dispose_unmap_extent(pag_group(sc->sa.pag), agbno,
+				*aglenp);
 
 		rs->force_roll = true;
 
@@ -419,7 +424,8 @@ xreap_agextent_iter(
 			 * records from the refcountbt, which will remove the
 			 * rmap record as well.
 			 */
-			xfs_refcount_free_cow_extent(sc->tp, fsbno, *aglenp);
+			xfs_refcount_free_cow_extent(sc->tp, false, fsbno,
+					*aglenp);
 			return 0;
 		}
 
@@ -427,7 +433,7 @@ xreap_agextent_iter(
 				*aglenp, rs->oinfo);
 	}
 
-	trace_xreap_dispose_free_extent(sc->sa.pag, agbno, *aglenp);
+	trace_xreap_dispose_free_extent(pag_group(sc->sa.pag), agbno, *aglenp);
 
 	/*
 	 * Invalidate as many buffers as we can, starting at agbno.  If this
@@ -451,7 +457,7 @@ xreap_agextent_iter(
 	if (rs->oinfo == &XFS_RMAP_OINFO_COW) {
 		ASSERT(rs->resv == XFS_AG_RESV_NONE);
 
-		xfs_refcount_free_cow_extent(sc->tp, fsbno, *aglenp);
+		xfs_refcount_free_cow_extent(sc->tp, false, fsbno, *aglenp);
 		error = xfs_free_extent_later(sc->tp, fsbno, *aglenp, NULL,
 				rs->resv, XFS_FREE_EXTENT_SKIP_DISCARD);
 		if (error)
@@ -678,6 +684,225 @@ xrep_reap_fsblocks(
 	return 0;
 }
 
+#ifdef CONFIG_XFS_RT
+/*
+ * Figure out the longest run of blocks that we can dispose of with a single
+ * call.  Cross-linked blocks should have their reverse mappings removed, but
+ * single-owner extents can be freed.  Units are rt blocks, not rt extents.
+ */
+STATIC int
+xreap_rgextent_select(
+	struct xreap_state	*rs,
+	xfs_rgblock_t		rgbno,
+	xfs_rgblock_t		rgbno_next,
+	bool			*crosslinked,
+	xfs_extlen_t		*rglenp)
+{
+	struct xfs_scrub	*sc = rs->sc;
+	struct xfs_btree_cur	*cur;
+	xfs_rgblock_t		bno = rgbno + 1;
+	xfs_extlen_t		len = 1;
+	int			error;
+
+	/*
+	 * Determine if there are any other rmap records covering the first
+	 * block of this extent.  If so, the block is crosslinked.
+	 */
+	cur = xfs_rtrmapbt_init_cursor(sc->tp, sc->sr.rtg);
+	error = xfs_rmap_has_other_keys(cur, rgbno, 1, rs->oinfo,
+			crosslinked);
+	if (error)
+		goto out_cur;
+
+	/*
+	 * Figure out how many of the subsequent blocks have the same crosslink
+	 * status.
+	 */
+	while (bno < rgbno_next) {
+		bool		also_crosslinked;
+
+		error = xfs_rmap_has_other_keys(cur, bno, 1, rs->oinfo,
+				&also_crosslinked);
+		if (error)
+			goto out_cur;
+
+		if (*crosslinked != also_crosslinked)
+			break;
+
+		len++;
+		bno++;
+	}
+
+	*rglenp = len;
+	trace_xreap_agextent_select(rtg_group(sc->sr.rtg), rgbno, len,
+			*crosslinked);
+out_cur:
+	xfs_btree_del_cursor(cur, error);
+	return error;
+}
+
+/*
+ * Dispose of as much of the beginning of this rtgroup extent as possible.
+ * The number of blocks disposed of will be returned in @rglenp.
+ */
+STATIC int
+xreap_rgextent_iter(
+	struct xreap_state	*rs,
+	xfs_rgblock_t		rgbno,
+	xfs_extlen_t		*rglenp,
+	bool			crosslinked)
+{
+	struct xfs_scrub	*sc = rs->sc;
+	xfs_rtblock_t		rtbno;
+	int			error;
+
+	/*
+	 * The only caller so far is CoW fork repair, so we only know how to
+	 * unlink or free CoW staging extents.  Here we don't have to worry
+	 * about invalidating buffers!
+	 */
+	if (rs->oinfo != &XFS_RMAP_OINFO_COW) {
+		ASSERT(rs->oinfo == &XFS_RMAP_OINFO_COW);
+		return -EFSCORRUPTED;
+	}
+	ASSERT(rs->resv == XFS_AG_RESV_NONE);
+
+	rtbno = xfs_rgbno_to_rtb(sc->sr.rtg, rgbno);
+
+	/*
+	 * If there are other rmappings, this block is cross linked and must
+	 * not be freed.  Remove the forward and reverse mapping and move on.
+	 */
+	if (crosslinked) {
+		trace_xreap_dispose_unmap_extent(rtg_group(sc->sr.rtg), rgbno,
+				*rglenp);
+
+		xfs_refcount_free_cow_extent(sc->tp, true, rtbno, *rglenp);
+		rs->deferred++;
+		return 0;
+	}
+
+	trace_xreap_dispose_free_extent(rtg_group(sc->sr.rtg), rgbno, *rglenp);
+
+	/*
+	 * The CoW staging extent is not crosslinked.  Use deferred work items
+	 * to remove the refcountbt records (which removes the rmap records)
+	 * and free the extent.  We're not worried about the system going down
+	 * here because log recovery walks the refcount btree to clean out the
+	 * CoW staging extents.
+	 */
+	xfs_refcount_free_cow_extent(sc->tp, true, rtbno, *rglenp);
+	error = xfs_free_extent_later(sc->tp, rtbno, *rglenp, NULL,
+			rs->resv,
+			XFS_FREE_EXTENT_REALTIME |
+			XFS_FREE_EXTENT_SKIP_DISCARD);
+	if (error)
+		return error;
+
+	rs->deferred++;
+	return 0;
+}
+
+#define XREAP_RTGLOCK_ALL	(XFS_RTGLOCK_BITMAP | \
+				 XFS_RTGLOCK_RMAP | \
+				 XFS_RTGLOCK_REFCOUNT)
+
+/*
+ * Break a rt file metadata extent into sub-extents by fate (crosslinked, not
+ * crosslinked), and dispose of each sub-extent separately.  The extent must
+ * be aligned to a realtime extent.
+ */
+STATIC int
+xreap_rtmeta_extent(
+	uint64_t		rtbno,
+	uint64_t		len,
+	void			*priv)
+{
+	struct xreap_state	*rs = priv;
+	struct xfs_scrub	*sc = rs->sc;
+	xfs_rgblock_t		rgbno = xfs_rtb_to_rgbno(sc->mp, rtbno);
+	xfs_rgblock_t		rgbno_next = rgbno + len;
+	int			error = 0;
+
+	ASSERT(sc->ip != NULL);
+	ASSERT(!sc->sr.rtg);
+
+	/*
+	 * We're reaping blocks after repairing file metadata, which means that
+	 * we have to init the xchk_ag structure ourselves.
+	 */
+	sc->sr.rtg = xfs_rtgroup_get(sc->mp, xfs_rtb_to_rgno(sc->mp, rtbno));
+	if (!sc->sr.rtg)
+		return -EFSCORRUPTED;
+
+	xfs_rtgroup_lock(sc->sr.rtg, XREAP_RTGLOCK_ALL);
+
+	while (rgbno < rgbno_next) {
+		xfs_extlen_t	rglen;
+		bool		crosslinked;
+
+		error = xreap_rgextent_select(rs, rgbno, rgbno_next,
+				&crosslinked, &rglen);
+		if (error)
+			goto out_unlock;
+
+		error = xreap_rgextent_iter(rs, rgbno, &rglen, crosslinked);
+		if (error)
+			goto out_unlock;
+
+		if (xreap_want_defer_finish(rs)) {
+			error = xfs_defer_finish(&sc->tp);
+			if (error)
+				goto out_unlock;
+			xreap_defer_finish_reset(rs);
+		} else if (xreap_want_roll(rs)) {
+			error = xfs_trans_roll_inode(&sc->tp, sc->ip);
+			if (error)
+				goto out_unlock;
+			xreap_reset(rs);
+		}
+
+		rgbno += rglen;
+	}
+
+out_unlock:
+	xfs_rtgroup_unlock(sc->sr.rtg, XREAP_RTGLOCK_ALL);
+	xfs_rtgroup_put(sc->sr.rtg);
+	sc->sr.rtg = NULL;
+	return error;
+}
+
+/*
+ * Dispose of every block of every rt metadata extent in the bitmap.
+ * Do not use this to dispose of the mappings in an ondisk inode fork.
+ */
+int
+xrep_reap_rtblocks(
+	struct xfs_scrub		*sc,
+	struct xrtb_bitmap		*bitmap,
+	const struct xfs_owner_info	*oinfo)
+{
+	struct xreap_state		rs = {
+		.sc			= sc,
+		.oinfo			= oinfo,
+		.resv			= XFS_AG_RESV_NONE,
+	};
+	int				error;
+
+	ASSERT(xfs_has_rmapbt(sc->mp));
+	ASSERT(sc->ip != NULL);
+
+	error = xrtb_bitmap_walk(bitmap, xreap_rtmeta_extent, &rs);
+	if (error)
+		return error;
+
+	if (xreap_dirty(&rs))
+		return xrep_defer_finish(sc);
+
+	return 0;
+}
+#endif /* CONFIG_XFS_RT */
+
 /*
  * Dispose of every block of an old metadata btree that used to be rooted in a
  * metadata directory file.
@@ -770,7 +995,8 @@ xreap_bmapi_select(
 	}
 
 	imap->br_blockcount = len;
-	trace_xreap_bmapi_select(sc->sa.pag, agbno, len, *crosslinked);
+	trace_xreap_bmapi_select(pag_group(sc->sa.pag), agbno, len,
+			*crosslinked);
 out_cur:
 	xfs_btree_del_cursor(cur, error);
 	return error;
@@ -909,7 +1135,8 @@ xreap_bmapi_binval(
 	}
 
 out:
-	trace_xreap_bmapi_binval(sc->sa.pag, agbno, imap->br_blockcount);
+	trace_xreap_bmapi_binval(pag_group(sc->sa.pag), agbno,
+			imap->br_blockcount);
 	return 0;
 }
 
@@ -936,7 +1163,7 @@ xrep_reap_bmapi_iter(
 		 * anybody else who thinks they own the block, even though that
 		 * runs the risk of stale buffer warnings in the future.
 		 */
-		trace_xreap_dispose_unmap_extent(sc->sa.pag,
+		trace_xreap_dispose_unmap_extent(pag_group(sc->sa.pag),
 				XFS_FSB_TO_AGBNO(sc->mp, imap->br_startblock),
 				imap->br_blockcount);
 
@@ -959,7 +1186,7 @@ xrep_reap_bmapi_iter(
 	 * by a block starting before the first block of the extent but overlap
 	 * anyway.
 	 */
-	trace_xreap_dispose_free_extent(sc->sa.pag,
+	trace_xreap_dispose_free_extent(pag_group(sc->sa.pag),
 			XFS_FSB_TO_AGBNO(sc->mp, imap->br_startblock),
 			imap->br_blockcount);
 
diff --git a/fs/xfs/scrub/reap.h b/fs/xfs/scrub/reap.h
index 70e5e6bbb8d3..4c8f62701fb3 100644
--- a/fs/xfs/scrub/reap.h
+++ b/fs/xfs/scrub/reap.h
@@ -17,6 +17,13 @@ int xrep_reap_ifork(struct xfs_scrub *sc, struct xfs_inode *ip, int whichfork);
 int xrep_reap_metadir_fsblocks(struct xfs_scrub *sc,
 		struct xfsb_bitmap *bitmap);
 
+#ifdef CONFIG_XFS_RT
+int xrep_reap_rtblocks(struct xfs_scrub *sc, struct xrtb_bitmap *bitmap,
+		const struct xfs_owner_info *oinfo);
+#else
+# define xrep_reap_rtblocks(...)	(-EOPNOTSUPP)
+#endif /* CONFIG_XFS_RT */
+
 /* Buffer cache scan context. */
 struct xrep_bufscan {
 	/* Disk address for the buffers we want to scan. */
diff --git a/fs/xfs/scrub/refcount.c b/fs/xfs/scrub/refcount.c
index 1c5e45cc6419..d46528023015 100644
--- a/fs/xfs/scrub/refcount.c
+++ b/fs/xfs/scrub/refcount.c
@@ -421,7 +421,7 @@ xchk_refcount_mergeable(
 	if (r1->rc_refcount != r2->rc_refcount)
 		return false;
 	if ((unsigned long long)r1->rc_blockcount + r2->rc_blockcount >
-			MAXREFCEXTLEN)
+			XFS_REFC_LEN_MAX)
 		return false;
 
 	return true;
diff --git a/fs/xfs/scrub/refcount_repair.c b/fs/xfs/scrub/refcount_repair.c
index 4e572b81c986..9c8cb5332da0 100644
--- a/fs/xfs/scrub/refcount_repair.c
+++ b/fs/xfs/scrub/refcount_repair.c
@@ -183,13 +183,13 @@ xrep_refc_stash(
 	if (xchk_should_terminate(sc, &error))
 		return error;
 
-	irec.rc_refcount = min_t(uint64_t, MAXREFCOUNT, refcount);
+	irec.rc_refcount = min_t(uint64_t, XFS_REFC_REFCOUNT_MAX, refcount);
 
 	error = xrep_refc_check_ext(rr->sc, &irec);
 	if (error)
 		return error;
 
-	trace_xrep_refc_found(sc->sa.pag, &irec);
+	trace_xrep_refc_found(pag_group(sc->sa.pag), &irec);
 
 	return xfarray_append(rr->refcount_records, &irec);
 }
@@ -422,7 +422,7 @@ xrep_refc_find_refcounts(
 	/*
 	 * Set up a bag to store all the rmap records that we're tracking to
 	 * generate a reference count record.  If the size of the bag exceeds
-	 * MAXREFCOUNT, we clamp rc_refcount.
+	 * XFS_REFC_REFCOUNT_MAX, we clamp rc_refcount.
 	 */
 	error = rcbag_init(sc->mp, sc->xmbtp, &rcstack);
 	if (error)
diff --git a/fs/xfs/scrub/repair.c b/fs/xfs/scrub/repair.c
index 61e414c81253..3b5288d3ef4e 100644
--- a/fs/xfs/scrub/repair.c
+++ b/fs/xfs/scrub/repair.c
@@ -42,6 +42,7 @@
 #include "xfs_rtgroup.h"
 #include "xfs_rtalloc.h"
 #include "xfs_metafile.h"
+#include "xfs_rtrefcount_btree.h"
 #include "scrub/scrub.h"
 #include "scrub/common.h"
 #include "scrub/trace.h"
@@ -1009,6 +1010,11 @@ xrep_rtgroup_btcur_init(
 	    (sr->rtlock_flags & XFS_RTGLOCK_RMAP) &&
 	    xfs_has_rtrmapbt(mp))
 		sr->rmap_cur = xfs_rtrmapbt_init_cursor(sc->tp, sr->rtg);
+
+	if (sc->sm->sm_type != XFS_SCRUB_TYPE_RTREFCBT &&
+	    (sr->rtlock_flags & XFS_RTGLOCK_REFCOUNT) &&
+	    xfs_has_rtreflink(mp))
+		sr->refc_cur = xfs_rtrefcountbt_init_cursor(sc->tp, sr->rtg);
 }
 
 /*
diff --git a/fs/xfs/scrub/repair.h b/fs/xfs/scrub/repair.h
index ac5962732d26..823c00d1a502 100644
--- a/fs/xfs/scrub/repair.h
+++ b/fs/xfs/scrub/repair.h
@@ -50,7 +50,9 @@ xrep_trans_commit(
 
 struct xbitmap;
 struct xagb_bitmap;
+struct xrgb_bitmap;
 struct xfsb_bitmap;
+struct xrtb_bitmap;
 
 int xrep_fix_freelist(struct xfs_scrub *sc, int alloc_flags);
 
@@ -98,6 +100,7 @@ int xrep_setup_nlinks(struct xfs_scrub *sc);
 int xrep_setup_symlink(struct xfs_scrub *sc, unsigned int *resblks);
 int xrep_setup_dirtree(struct xfs_scrub *sc);
 int xrep_setup_rtrmapbt(struct xfs_scrub *sc);
+int xrep_setup_rtrefcountbt(struct xfs_scrub *sc);
 
 /* Repair setup functions */
 int xrep_setup_ag_allocbt(struct xfs_scrub *sc);
@@ -157,11 +160,13 @@ int xrep_rtbitmap(struct xfs_scrub *sc);
 int xrep_rtsummary(struct xfs_scrub *sc);
 int xrep_rgsuperblock(struct xfs_scrub *sc);
 int xrep_rtrmapbt(struct xfs_scrub *sc);
+int xrep_rtrefcountbt(struct xfs_scrub *sc);
 #else
 # define xrep_rtbitmap			xrep_notsupported
 # define xrep_rtsummary			xrep_notsupported
 # define xrep_rgsuperblock		xrep_notsupported
 # define xrep_rtrmapbt			xrep_notsupported
+# define xrep_rtrefcountbt		xrep_notsupported
 #endif /* CONFIG_XFS_RT */
 
 #ifdef CONFIG_XFS_QUOTA
@@ -235,6 +240,7 @@ xrep_setup_nothing(
 #define xrep_setup_dirtree		xrep_setup_nothing
 #define xrep_setup_metapath		xrep_setup_nothing
 #define xrep_setup_rtrmapbt		xrep_setup_nothing
+#define xrep_setup_rtrefcountbt		xrep_setup_nothing
 
 #define xrep_setup_inode(sc, imap)	((void)0)
 
@@ -273,6 +279,7 @@ static inline int xrep_setup_symlink(struct xfs_scrub *sc, unsigned int *x)
 #define xrep_metapath			xrep_notsupported
 #define xrep_rgsuperblock		xrep_notsupported
 #define xrep_rtrmapbt			xrep_notsupported
+#define xrep_rtrefcountbt		xrep_notsupported
 
 #endif /* CONFIG_XFS_ONLINE_REPAIR */
 
diff --git a/fs/xfs/scrub/rgb_bitmap.h b/fs/xfs/scrub/rgb_bitmap.h
new file mode 100644
index 000000000000..4c3126b66dcb
--- /dev/null
+++ b/fs/xfs/scrub/rgb_bitmap.h
@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2020-2024 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#ifndef __XFS_SCRUB_RGB_BITMAP_H__
+#define __XFS_SCRUB_RGB_BITMAP_H__
+
+/* Bitmaps, but for type-checked for xfs_rgblock_t */
+
+struct xrgb_bitmap {
+	struct xbitmap32	rgbitmap;
+};
+
+static inline void xrgb_bitmap_init(struct xrgb_bitmap *bitmap)
+{
+	xbitmap32_init(&bitmap->rgbitmap);
+}
+
+static inline void xrgb_bitmap_destroy(struct xrgb_bitmap *bitmap)
+{
+	xbitmap32_destroy(&bitmap->rgbitmap);
+}
+
+static inline int xrgb_bitmap_set(struct xrgb_bitmap *bitmap,
+		xfs_rgblock_t start, xfs_extlen_t len)
+{
+	return xbitmap32_set(&bitmap->rgbitmap, start, len);
+}
+
+static inline int xrgb_bitmap_walk(struct xrgb_bitmap *bitmap,
+		xbitmap32_walk_fn fn, void *priv)
+{
+	return xbitmap32_walk(&bitmap->rgbitmap, fn, priv);
+}
+
+#endif /* __XFS_SCRUB_RGB_BITMAP_H__ */
diff --git a/fs/xfs/scrub/rmap_repair.c b/fs/xfs/scrub/rmap_repair.c
index c2c7b76cc25a..f5f73078ffe2 100644
--- a/fs/xfs/scrub/rmap_repair.c
+++ b/fs/xfs/scrub/rmap_repair.c
@@ -33,6 +33,7 @@
 #include "xfs_ag.h"
 #include "xfs_rtrmap_btree.h"
 #include "xfs_rtgroup.h"
+#include "xfs_rtrefcount_btree.h"
 #include "scrub/xfs_scrub.h"
 #include "scrub/scrub.h"
 #include "scrub/common.h"
@@ -519,6 +520,9 @@ xrep_rmap_scan_meta_btree(
 	case XFS_METAFILE_RTRMAP:
 		type = XFS_RTGI_RMAP;
 		break;
+	case XFS_METAFILE_RTREFCOUNT:
+		type = XFS_RTGI_REFCOUNT;
+		break;
 	default:
 		ASSERT(0);
 		return -EFSCORRUPTED;
@@ -545,6 +549,9 @@ found:
 	case XFS_METAFILE_RTRMAP:
 		cur = xfs_rtrmapbt_init_cursor(sc->tp, rtg);
 		break;
+	case XFS_METAFILE_RTREFCOUNT:
+		cur = xfs_rtrefcountbt_init_cursor(sc->tp, rtg);
+		break;
 	default:
 		ASSERT(0);
 		error = -EFSCORRUPTED;
diff --git a/fs/xfs/scrub/rtb_bitmap.h b/fs/xfs/scrub/rtb_bitmap.h
new file mode 100644
index 000000000000..1313ef605511
--- /dev/null
+++ b/fs/xfs/scrub/rtb_bitmap.h
@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2022-2024 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#ifndef __XFS_SCRUB_RTB_BITMAP_H__
+#define __XFS_SCRUB_RTB_BITMAP_H__
+
+/* Bitmaps, but for type-checked for xfs_rtblock_t */
+
+struct xrtb_bitmap {
+	struct xbitmap64	rtbitmap;
+};
+
+static inline void xrtb_bitmap_init(struct xrtb_bitmap *bitmap)
+{
+	xbitmap64_init(&bitmap->rtbitmap);
+}
+
+static inline void xrtb_bitmap_destroy(struct xrtb_bitmap *bitmap)
+{
+	xbitmap64_destroy(&bitmap->rtbitmap);
+}
+
+static inline int xrtb_bitmap_set(struct xrtb_bitmap *bitmap,
+		xfs_rtblock_t start, xfs_filblks_t len)
+{
+	return xbitmap64_set(&bitmap->rtbitmap, start, len);
+}
+
+static inline int xrtb_bitmap_walk(struct xrtb_bitmap *bitmap,
+		xbitmap64_walk_fn fn, void *priv)
+{
+	return xbitmap64_walk(&bitmap->rtbitmap, fn, priv);
+}
+
+#endif	/* __XFS_SCRUB_RTB_BITMAP_H__ */
diff --git a/fs/xfs/scrub/rtbitmap.c b/fs/xfs/scrub/rtbitmap.c
index 28c90a31f4c3..e8c776a34c1d 100644
--- a/fs/xfs/scrub/rtbitmap.c
+++ b/fs/xfs/scrub/rtbitmap.c
@@ -105,6 +105,8 @@ xchk_rtbitmap_xref(
 		return;
 
 	xchk_xref_has_no_rt_owner(sc, rgbno, blockcount);
+	xchk_xref_is_not_rt_shared(sc, rgbno, blockcount);
+	xchk_xref_is_not_rt_cow_staging(sc, rgbno, blockcount);
 
 	if (rtb->next_free_rgbno < rgbno)
 		xchk_xref_has_rt_owner(sc, rtb->next_free_rgbno,
diff --git a/fs/xfs/scrub/rtbitmap_repair.c b/fs/xfs/scrub/rtbitmap_repair.c
index c6e33834c5ae..203a1a97c502 100644
--- a/fs/xfs/scrub/rtbitmap_repair.c
+++ b/fs/xfs/scrub/rtbitmap_repair.c
@@ -23,6 +23,7 @@
 #include "xfs_rtbitmap.h"
 #include "xfs_rtgroup.h"
 #include "xfs_extent_busy.h"
+#include "xfs_refcount.h"
 #include "scrub/scrub.h"
 #include "scrub/common.h"
 #include "scrub/trace.h"
@@ -183,7 +184,8 @@ xrep_rtbitmap_mark_free(
 	xfs_rgblock_t		rgbno)
 {
 	struct xfs_mount	*mp = rtb->sc->mp;
-	struct xfs_rtgroup	*rtg = rtb->sc->sr.rtg;
+	struct xchk_rt		*sr = &rtb->sc->sr;
+	struct xfs_rtgroup	*rtg = sr->rtg;
 	xfs_rtxnum_t		startrtx;
 	xfs_rtxnum_t		nextrtx;
 	xrep_wordoff_t		wordoff, nextwordoff;
@@ -191,6 +193,7 @@ xrep_rtbitmap_mark_free(
 	unsigned int		bufwsize;
 	xfs_extlen_t		mod;
 	xfs_rtword_t		mask;
+	enum xbtree_recpacking	outcome;
 	int			error;
 
 	if (!xfs_verify_rgbext(rtg, rtb->next_rgbno, rgbno - rtb->next_rgbno))
@@ -210,6 +213,25 @@ xrep_rtbitmap_mark_free(
 	if (mod != mp->m_sb.sb_rextsize - 1)
 		return -EFSCORRUPTED;
 
+	/* Must not be shared or CoW staging. */
+	if (sr->refc_cur) {
+		error = xfs_refcount_has_records(sr->refc_cur,
+				XFS_REFC_DOMAIN_SHARED, rtb->next_rgbno,
+				rgbno - rtb->next_rgbno, &outcome);
+		if (error)
+			return error;
+		if (outcome != XBTREE_RECPACKING_EMPTY)
+			return -EFSCORRUPTED;
+
+		error = xfs_refcount_has_records(sr->refc_cur,
+				XFS_REFC_DOMAIN_COW, rtb->next_rgbno,
+				rgbno - rtb->next_rgbno, &outcome);
+		if (error)
+			return error;
+		if (outcome != XBTREE_RECPACKING_EMPTY)
+			return -EFSCORRUPTED;
+	}
+
 	trace_xrep_rtbitmap_record_free(mp, startrtx, nextrtx - 1);
 
 	/* Set bits as needed to round startrtx up to the nearest word. */
diff --git a/fs/xfs/scrub/rtrefcount.c b/fs/xfs/scrub/rtrefcount.c
new file mode 100644
index 000000000000..4c5dffc73641
--- /dev/null
+++ b/fs/xfs/scrub/rtrefcount.c
@@ -0,0 +1,661 @@
+// 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_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_inode.h"
+#include "xfs_rtbitmap.h"
+#include "xfs_rtgroup.h"
+#include "xfs_metafile.h"
+#include "xfs_rtrefcount_btree.h"
+#include "xfs_rtalloc.h"
+#include "scrub/scrub.h"
+#include "scrub/common.h"
+#include "scrub/btree.h"
+#include "scrub/repair.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);
+
+	if (xchk_could_repair(sc)) {
+		error = xrep_setup_rtrefcountbt(sc);
+		if (error)
+			return error;
+	}
+
+	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, rtg_refcount(sc->sr.rtg));
+	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;
+
+	/* The next rtgroup block where we aren't expecting shared extents. */
+	xfs_rgblock_t			next_unshared_rgbno;
+
+	/* Number of CoW blocks we expect. */
+	xfs_extlen_t			cow_blocks;
+
+	/* Was the last record a shared or CoW staging extent? */
+	enum xfs_refc_domain		prev_domain;
+};
+
+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));
+}
+
+STATIC int
+xchk_rtrefcountbt_rmap_check_gap(
+	struct xfs_btree_cur		*cur,
+	const struct xfs_rmap_irec	*rec,
+	void				*priv)
+{
+	xfs_rgblock_t			*next_bno = priv;
+
+	if (*next_bno != NULLRGBLOCK && 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_rtrefcountbt_xref_gaps(
+	struct xfs_scrub	*sc,
+	struct xchk_rtrefcbt_records *rrc,
+	xfs_rtblock_t		bno)
+{
+	struct xfs_rmap_irec	low;
+	struct xfs_rmap_irec	high;
+	xfs_rgblock_t		next_bno = NULLRGBLOCK;
+	int			error;
+
+	if (bno <= rrc->next_unshared_rgbno || !sc->sr.rmap_cur ||
+            xchk_skip_xref(sc->sm))
+		return;
+
+	memset(&low, 0, sizeof(low));
+	low.rm_startblock = rrc->next_unshared_rgbno;
+	memset(&high, 0xFF, sizeof(high));
+	high.rm_startblock = bno - 1;
+
+	error = xfs_rmap_query_range(sc->sr.rmap_cur, &low, &high,
+			xchk_rtrefcountbt_rmap_check_gap, &next_bno);
+	if (error == -ECANCELED)
+		xchk_btree_xref_set_corrupt(sc, sc->sr.rmap_cur, 0);
+	else
+		xchk_should_check_xref(sc, &error, &sc->sr.rmap_cur);
+}
+
+/* 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;
+
+	/* 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_rtrefcountbt_check_mergeable(bs, rrc, &irec);
+	xchk_rtrefcountbt_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_rtrefcountbt_xref_gaps(bs->sc, rrc, irec.rc_startblock);
+		rrc->next_unshared_rgbno = 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,
+	const struct xfs_owner_info *btree_oinfo,
+	xfs_extlen_t		cow_blocks)
+{
+	xfs_filblks_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,
+		.next_unshared_rgbno	= 0,
+		.prev_domain		= XFS_REFC_DOMAIN_SHARED,
+	};
+	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, rtg_refcount(sc->sr.rtg)->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;
+
+	/*
+	 * Check that all blocks between the last refcount > 1 record and the
+	 * end of the rt volume have at most one reverse mapping.
+	 */
+	xchk_rtrefcountbt_xref_gaps(sc, &rrc, sc->mp->m_sb.sb_rblocks);
+
+	xchk_refcount_xref_rmap(sc, &btree_oinfo, rrc.cow_blocks);
+
+	return 0;
+}
+
+/* xref check that a cow staging extent is marked in the rtrefcountbt. */
+void
+xchk_xref_is_rt_cow_staging(
+	struct xfs_scrub		*sc,
+	xfs_rgblock_t			bno,
+	xfs_extlen_t			len)
+{
+	struct xfs_refcount_irec	rc;
+	int				has_refcount;
+	int				error;
+
+	if (!sc->sr.refc_cur || xchk_skip_xref(sc->sm))
+		return;
+
+	/* Find the CoW staging extent. */
+	error = xfs_refcount_lookup_le(sc->sr.refc_cur, XFS_REFC_DOMAIN_COW,
+			bno, &has_refcount);
+	if (!xchk_should_check_xref(sc, &error, &sc->sr.refc_cur))
+		return;
+	if (!has_refcount) {
+		xchk_btree_xref_set_corrupt(sc, sc->sr.refc_cur, 0);
+		return;
+	}
+
+	error = xfs_refcount_get_rec(sc->sr.refc_cur, &rc, &has_refcount);
+	if (!xchk_should_check_xref(sc, &error, &sc->sr.refc_cur))
+		return;
+	if (!has_refcount) {
+		xchk_btree_xref_set_corrupt(sc, sc->sr.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->sr.refc_cur, 0);
+}
+
+/*
+ * xref check that the extent is not shared.  Only file data blocks
+ * can have multiple owners.
+ */
+void
+xchk_xref_is_not_rt_shared(
+	struct xfs_scrub	*sc,
+	xfs_rgblock_t		bno,
+	xfs_extlen_t		len)
+{
+	enum xbtree_recpacking	outcome;
+	int			error;
+
+	if (!sc->sr.refc_cur || xchk_skip_xref(sc->sm))
+		return;
+
+	error = xfs_refcount_has_records(sc->sr.refc_cur,
+			XFS_REFC_DOMAIN_SHARED, bno, len, &outcome);
+	if (!xchk_should_check_xref(sc, &error, &sc->sr.refc_cur))
+		return;
+	if (outcome != XBTREE_RECPACKING_EMPTY)
+		xchk_btree_xref_set_corrupt(sc, sc->sr.refc_cur, 0);
+}
+
+/* xref check that the extent is not being used for CoW staging. */
+void
+xchk_xref_is_not_rt_cow_staging(
+	struct xfs_scrub	*sc,
+	xfs_rgblock_t		bno,
+	xfs_extlen_t		len)
+{
+	enum xbtree_recpacking	outcome;
+	int			error;
+
+	if (!sc->sr.refc_cur || xchk_skip_xref(sc->sm))
+		return;
+
+	error = xfs_refcount_has_records(sc->sr.refc_cur, XFS_REFC_DOMAIN_COW,
+			bno, len, &outcome);
+	if (!xchk_should_check_xref(sc, &error, &sc->sr.refc_cur))
+		return;
+	if (outcome != XBTREE_RECPACKING_EMPTY)
+		xchk_btree_xref_set_corrupt(sc, sc->sr.refc_cur, 0);
+}
diff --git a/fs/xfs/scrub/rtrefcount_repair.c b/fs/xfs/scrub/rtrefcount_repair.c
new file mode 100644
index 000000000000..257cfb24beb4
--- /dev/null
+++ b/fs/xfs/scrub/rtrefcount_repair.c
@@ -0,0 +1,783 @@
+// 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_defer.h"
+#include "xfs_btree.h"
+#include "xfs_btree_staging.h"
+#include "xfs_bit.h"
+#include "xfs_log_format.h"
+#include "xfs_trans.h"
+#include "xfs_sb.h"
+#include "xfs_alloc.h"
+#include "xfs_ialloc.h"
+#include "xfs_rmap.h"
+#include "xfs_rmap_btree.h"
+#include "xfs_rtrmap_btree.h"
+#include "xfs_refcount.h"
+#include "xfs_rtrefcount_btree.h"
+#include "xfs_error.h"
+#include "xfs_health.h"
+#include "xfs_inode.h"
+#include "xfs_quota.h"
+#include "xfs_rtalloc.h"
+#include "xfs_ag.h"
+#include "xfs_rtgroup.h"
+#include "xfs_rtbitmap.h"
+#include "scrub/xfs_scrub.h"
+#include "scrub/scrub.h"
+#include "scrub/common.h"
+#include "scrub/btree.h"
+#include "scrub/trace.h"
+#include "scrub/repair.h"
+#include "scrub/bitmap.h"
+#include "scrub/fsb_bitmap.h"
+#include "scrub/xfile.h"
+#include "scrub/xfarray.h"
+#include "scrub/newbt.h"
+#include "scrub/reap.h"
+#include "scrub/rcbag.h"
+
+/*
+ * Rebuilding the Reference Count Btree
+ * ====================================
+ *
+ * This algorithm is "borrowed" from xfs_repair.  Imagine the rmap
+ * entries as rectangles representing extents of physical blocks, and
+ * that the rectangles can be laid down to allow them to overlap each
+ * other; then we know that we must emit a refcnt btree entry wherever
+ * the amount of overlap changes, i.e. the emission stimulus is
+ * level-triggered:
+ *
+ *                 -    ---
+ *       --      ----- ----   ---        ------
+ * --   ----     ----------- ----     ---------
+ * -------------------------------- -----------
+ * ^ ^  ^^ ^^    ^ ^^ ^^^  ^^^^  ^ ^^ ^  ^     ^
+ * 2 1  23 21    3 43 234  2123  1 01 2  3     0
+ *
+ * For our purposes, a rmap is a tuple (startblock, len, fileoff, owner).
+ *
+ * Note that in the actual refcnt btree we don't store the refcount < 2
+ * cases because the bnobt tells us which blocks are free; single-use
+ * blocks aren't recorded in the bnobt or the refcntbt.  If the rmapbt
+ * supports storing multiple entries covering a given block we could
+ * theoretically dispense with the refcntbt and simply count rmaps, but
+ * that's inefficient in the (hot) write path, so we'll take the cost of
+ * the extra tree to save time.  Also there's no guarantee that rmap
+ * will be enabled.
+ *
+ * Given an array of rmaps sorted by physical block number, a starting
+ * physical block (sp), a bag to hold rmaps that cover sp, and the next
+ * physical block where the level changes (np), we can reconstruct the
+ * rt refcount btree as follows:
+ *
+ * While there are still unprocessed rmaps in the array,
+ *  - Set sp to the physical block (pblk) of the next unprocessed rmap.
+ *  - Add to the bag all rmaps in the array where startblock == sp.
+ *  - Set np to the physical block where the bag size will change.  This
+ *    is the minimum of (the pblk of the next unprocessed rmap) and
+ *    (startblock + len of each rmap in the bag).
+ *  - Record the bag size as old_bag_size.
+ *
+ *  - While the bag isn't empty,
+ *     - Remove from the bag all rmaps where startblock + len == np.
+ *     - Add to the bag all rmaps in the array where startblock == np.
+ *     - If the bag size isn't old_bag_size, store the refcount entry
+ *       (sp, np - sp, bag_size) in the refcnt btree.
+ *     - If the bag is empty, break out of the inner loop.
+ *     - Set old_bag_size to the bag size
+ *     - Set sp = np.
+ *     - Set np to the physical block where the bag size will change.
+ *       This is the minimum of (the pblk of the next unprocessed rmap)
+ *       and (startblock + len of each rmap in the bag).
+ *
+ * Like all the other repairers, we make a list of all the refcount
+ * records we need, then reinitialize the rt refcount btree root and
+ * insert all the records.
+ */
+
+struct xrep_rtrefc {
+	/* refcount extents */
+	struct xfarray		*refcount_records;
+
+	/* new refcountbt information */
+	struct xrep_newbt	new_btree;
+
+	/* old refcountbt blocks */
+	struct xfsb_bitmap	old_rtrefcountbt_blocks;
+
+	struct xfs_scrub	*sc;
+
+	/* get_records()'s position in the rt refcount record array. */
+	xfarray_idx_t		array_cur;
+
+	/* # of refcountbt blocks */
+	xfs_filblks_t		btblocks;
+};
+
+/* Set us up to repair refcount btrees. */
+int
+xrep_setup_rtrefcountbt(
+	struct xfs_scrub	*sc)
+{
+	char			*descr;
+	int			error;
+
+	descr = xchk_xfile_ag_descr(sc, "rmap record bag");
+	error = xrep_setup_xfbtree(sc, descr);
+	kfree(descr);
+	return error;
+}
+
+/* Check for any obvious conflicts with this shared/CoW staging extent. */
+STATIC int
+xrep_rtrefc_check_ext(
+	struct xfs_scrub		*sc,
+	const struct xfs_refcount_irec	*rec)
+{
+	xfs_rgblock_t			last;
+
+	if (xfs_rtrefcount_check_irec(sc->sr.rtg, rec) != NULL)
+		return -EFSCORRUPTED;
+
+	if (xfs_rgbno_to_rtxoff(sc->mp, rec->rc_startblock) != 0)
+		return -EFSCORRUPTED;
+
+	last = rec->rc_startblock + rec->rc_blockcount - 1;
+	if (xfs_rgbno_to_rtxoff(sc->mp, last) != sc->mp->m_sb.sb_rextsize - 1)
+		return -EFSCORRUPTED;
+
+	/* Make sure this isn't free space or misaligned. */
+	return xrep_require_rtext_inuse(sc, rec->rc_startblock,
+			rec->rc_blockcount);
+}
+
+/* Record a reference count extent. */
+STATIC int
+xrep_rtrefc_stash(
+	struct xrep_rtrefc		*rr,
+	enum xfs_refc_domain		domain,
+	xfs_rgblock_t			bno,
+	xfs_extlen_t			len,
+	uint64_t			refcount)
+{
+	struct xfs_refcount_irec	irec = {
+		.rc_startblock		= bno,
+		.rc_blockcount		= len,
+		.rc_refcount		= refcount,
+		.rc_domain		= domain,
+	};
+	int				error = 0;
+
+	if (xchk_should_terminate(rr->sc, &error))
+		return error;
+
+	irec.rc_refcount = min_t(uint64_t, XFS_REFC_REFCOUNT_MAX, refcount);
+
+	error = xrep_rtrefc_check_ext(rr->sc, &irec);
+	if (error)
+		return error;
+
+	trace_xrep_refc_found(rtg_group(rr->sc->sr.rtg), &irec);
+
+	return xfarray_append(rr->refcount_records, &irec);
+}
+
+/* Record a CoW staging extent. */
+STATIC int
+xrep_rtrefc_stash_cow(
+	struct xrep_rtrefc		*rr,
+	xfs_rgblock_t			bno,
+	xfs_extlen_t			len)
+{
+	return xrep_rtrefc_stash(rr, XFS_REFC_DOMAIN_COW, bno, len, 1);
+}
+
+/* Decide if an rmap could describe a shared extent. */
+static inline bool
+xrep_rtrefc_rmap_shareable(
+	const struct xfs_rmap_irec	*rmap)
+{
+	/* rt metadata are never sharable */
+	if (XFS_RMAP_NON_INODE_OWNER(rmap->rm_owner))
+		return false;
+
+	/* Unwritten file blocks are not shareable. */
+	if (rmap->rm_flags & XFS_RMAP_UNWRITTEN)
+		return false;
+
+	return true;
+}
+
+/* Grab the next (abbreviated) rmap record from the rmapbt. */
+STATIC int
+xrep_rtrefc_walk_rmaps(
+	struct xrep_rtrefc	*rr,
+	struct xfs_rmap_irec	*rmap,
+	bool			*have_rec)
+{
+	struct xfs_btree_cur	*cur = rr->sc->sr.rmap_cur;
+	struct xfs_mount	*mp = cur->bc_mp;
+	int			have_gt;
+	int			error = 0;
+
+	*have_rec = false;
+
+	/*
+	 * Loop through the remaining rmaps.  Remember CoW staging
+	 * extents and the refcountbt blocks from the old tree for later
+	 * disposal.  We can only share written data fork extents, so
+	 * keep looping until we find an rmap for one.
+	 */
+	do {
+		if (xchk_should_terminate(rr->sc, &error))
+			return error;
+
+		error = xfs_btree_increment(cur, 0, &have_gt);
+		if (error)
+			return error;
+		if (!have_gt)
+			return 0;
+
+		error = xfs_rmap_get_rec(cur, rmap, &have_gt);
+		if (error)
+			return error;
+		if (XFS_IS_CORRUPT(mp, !have_gt)) {
+			xfs_btree_mark_sick(cur);
+			return -EFSCORRUPTED;
+		}
+
+		if (rmap->rm_owner == XFS_RMAP_OWN_COW) {
+			error = xrep_rtrefc_stash_cow(rr, rmap->rm_startblock,
+					rmap->rm_blockcount);
+			if (error)
+				return error;
+		} else if (xfs_is_sb_inum(mp, rmap->rm_owner) ||
+			   (rmap->rm_flags & (XFS_RMAP_ATTR_FORK |
+					      XFS_RMAP_BMBT_BLOCK))) {
+			xfs_btree_mark_sick(cur);
+			return -EFSCORRUPTED;
+		}
+	} while (!xrep_rtrefc_rmap_shareable(rmap));
+
+	*have_rec = true;
+	return 0;
+}
+
+static inline uint32_t
+xrep_rtrefc_encode_startblock(
+	const struct xfs_refcount_irec	*irec)
+{
+	uint32_t			start;
+
+	start = irec->rc_startblock & ~XFS_REFC_COWFLAG;
+	if (irec->rc_domain == XFS_REFC_DOMAIN_COW)
+		start |= XFS_REFC_COWFLAG;
+
+	return start;
+}
+
+/*
+ * Compare two refcount records.  We want to sort in order of increasing block
+ * number.
+ */
+static int
+xrep_rtrefc_extent_cmp(
+	const void			*a,
+	const void			*b)
+{
+	const struct xfs_refcount_irec	*ap = a;
+	const struct xfs_refcount_irec	*bp = b;
+	uint32_t			sa, sb;
+
+	sa = xrep_rtrefc_encode_startblock(ap);
+	sb = xrep_rtrefc_encode_startblock(bp);
+
+	if (sa > sb)
+		return 1;
+	if (sa < sb)
+		return -1;
+	return 0;
+}
+
+/*
+ * Sort the refcount extents by startblock or else the btree records will be in
+ * the wrong order.  Make sure the records do not overlap in physical space.
+ */
+STATIC int
+xrep_rtrefc_sort_records(
+	struct xrep_rtrefc		*rr)
+{
+	struct xfs_refcount_irec	irec;
+	xfarray_idx_t			cur;
+	enum xfs_refc_domain		dom = XFS_REFC_DOMAIN_SHARED;
+	xfs_rgblock_t			next_rgbno = 0;
+	int				error;
+
+	error = xfarray_sort(rr->refcount_records, xrep_rtrefc_extent_cmp,
+			XFARRAY_SORT_KILLABLE);
+	if (error)
+		return error;
+
+	foreach_xfarray_idx(rr->refcount_records, cur) {
+		if (xchk_should_terminate(rr->sc, &error))
+			return error;
+
+		error = xfarray_load(rr->refcount_records, cur, &irec);
+		if (error)
+			return error;
+
+		if (dom == XFS_REFC_DOMAIN_SHARED &&
+		    irec.rc_domain == XFS_REFC_DOMAIN_COW) {
+			dom = irec.rc_domain;
+			next_rgbno = 0;
+		}
+
+		if (dom != irec.rc_domain)
+			return -EFSCORRUPTED;
+		if (irec.rc_startblock < next_rgbno)
+			return -EFSCORRUPTED;
+
+		next_rgbno = irec.rc_startblock + irec.rc_blockcount;
+	}
+
+	return error;
+}
+
+/* Record extents that belong to the realtime refcount inode. */
+STATIC int
+xrep_rtrefc_walk_rmap(
+	struct xfs_btree_cur		*cur,
+	const struct xfs_rmap_irec	*rec,
+	void				*priv)
+{
+	struct xrep_rtrefc		*rr = priv;
+	int				error = 0;
+
+	if (xchk_should_terminate(rr->sc, &error))
+		return error;
+
+	/* Skip extents which are not owned by this inode and fork. */
+	if (rec->rm_owner != rr->sc->ip->i_ino)
+		return 0;
+
+	error = xrep_check_ino_btree_mapping(rr->sc, rec);
+	if (error)
+		return error;
+
+	return xfsb_bitmap_set(&rr->old_rtrefcountbt_blocks,
+			xfs_gbno_to_fsb(cur->bc_group, rec->rm_startblock),
+			rec->rm_blockcount);
+}
+
+/*
+ * Walk forward through the rmap btree to collect all rmaps starting at
+ * @bno in @rmap_bag.  These represent the file(s) that share ownership of
+ * the current block.  Upon return, the rmap cursor points to the last record
+ * satisfying the startblock constraint.
+ */
+static int
+xrep_rtrefc_push_rmaps_at(
+	struct xrep_rtrefc	*rr,
+	struct rcbag		*rcstack,
+	xfs_rgblock_t		bno,
+	struct xfs_rmap_irec	*rmap,
+	bool			*have)
+{
+	struct xfs_scrub	*sc = rr->sc;
+	int			have_gt;
+	int			error;
+
+	while (*have && rmap->rm_startblock == bno) {
+		error = rcbag_add(rcstack, rr->sc->tp, rmap);
+		if (error)
+			return error;
+
+		error = xrep_rtrefc_walk_rmaps(rr, rmap, have);
+		if (error)
+			return error;
+	}
+
+	error = xfs_btree_decrement(sc->sr.rmap_cur, 0, &have_gt);
+	if (error)
+		return error;
+	if (XFS_IS_CORRUPT(sc->mp, !have_gt)) {
+		xfs_btree_mark_sick(sc->sr.rmap_cur);
+		return -EFSCORRUPTED;
+	}
+
+	return 0;
+}
+
+/* Scan one AG for reverse mappings for the realtime refcount btree. */
+STATIC int
+xrep_rtrefc_scan_ag(
+	struct xrep_rtrefc	*rr,
+	struct xfs_perag	*pag)
+{
+	struct xfs_scrub	*sc = rr->sc;
+	int			error;
+
+	error = xrep_ag_init(sc, pag, &sc->sa);
+	if (error)
+		return error;
+
+	error = xfs_rmap_query_all(sc->sa.rmap_cur, xrep_rtrefc_walk_rmap, rr);
+	xchk_ag_free(sc, &sc->sa);
+	return error;
+}
+
+/* Iterate all the rmap records to generate reference count data. */
+STATIC int
+xrep_rtrefc_find_refcounts(
+	struct xrep_rtrefc	*rr)
+{
+	struct xfs_scrub	*sc = rr->sc;
+	struct rcbag		*rcstack;
+	struct xfs_perag	*pag = NULL;
+	uint64_t		old_stack_height;
+	xfs_rgblock_t		sbno;
+	xfs_rgblock_t		cbno;
+	xfs_rgblock_t		nbno;
+	bool			have;
+	int			error;
+
+	/* Scan for old rtrefc btree blocks. */
+	while ((pag = xfs_perag_next(sc->mp, pag))) {
+		error = xrep_rtrefc_scan_ag(rr, pag);
+		if (error) {
+			xfs_perag_rele(pag);
+			return error;
+		}
+	}
+
+	xrep_rtgroup_btcur_init(sc, &sc->sr);
+
+	/*
+	 * Set up a bag to store all the rmap records that we're tracking to
+	 * generate a reference count record.  If this exceeds
+	 * XFS_REFC_REFCOUNT_MAX, we clamp rc_refcount.
+	 */
+	error = rcbag_init(sc->mp, sc->xmbtp, &rcstack);
+	if (error)
+		goto out_cur;
+
+	/* Start the rtrmapbt cursor to the left of all records. */
+	error = xfs_btree_goto_left_edge(sc->sr.rmap_cur);
+	if (error)
+		goto out_bag;
+
+	/* Process reverse mappings into refcount data. */
+	while (xfs_btree_has_more_records(sc->sr.rmap_cur)) {
+		struct xfs_rmap_irec	rmap;
+
+		/* Push all rmaps with pblk == sbno onto the stack */
+		error = xrep_rtrefc_walk_rmaps(rr, &rmap, &have);
+		if (error)
+			goto out_bag;
+		if (!have)
+			break;
+		sbno = cbno = rmap.rm_startblock;
+		error = xrep_rtrefc_push_rmaps_at(rr, rcstack, sbno, &rmap,
+				&have);
+		if (error)
+			goto out_bag;
+
+		/* Set nbno to the bno of the next refcount change */
+		error = rcbag_next_edge(rcstack, sc->tp, &rmap, have, &nbno);
+		if (error)
+			goto out_bag;
+
+		ASSERT(nbno > sbno);
+		old_stack_height = rcbag_count(rcstack);
+
+		/* While stack isn't empty... */
+		while (rcbag_count(rcstack) > 0) {
+			/* Pop all rmaps that end at nbno */
+			error = rcbag_remove_ending_at(rcstack, sc->tp, nbno);
+			if (error)
+				goto out_bag;
+
+			/* Push array items that start at nbno */
+			error = xrep_rtrefc_walk_rmaps(rr, &rmap, &have);
+			if (error)
+				goto out_bag;
+			if (have) {
+				error = xrep_rtrefc_push_rmaps_at(rr, rcstack,
+						nbno, &rmap, &have);
+				if (error)
+					goto out_bag;
+			}
+
+			/* Emit refcount if necessary */
+			ASSERT(nbno > cbno);
+			if (rcbag_count(rcstack) != old_stack_height) {
+				if (old_stack_height > 1) {
+					error = xrep_rtrefc_stash(rr,
+							XFS_REFC_DOMAIN_SHARED,
+							cbno, nbno - cbno,
+							old_stack_height);
+					if (error)
+						goto out_bag;
+				}
+				cbno = nbno;
+			}
+
+			/* Stack empty, go find the next rmap */
+			if (rcbag_count(rcstack) == 0)
+				break;
+			old_stack_height = rcbag_count(rcstack);
+			sbno = nbno;
+
+			/* Set nbno to the bno of the next refcount change */
+			error = rcbag_next_edge(rcstack, sc->tp, &rmap, have,
+					&nbno);
+			if (error)
+				goto out_bag;
+
+			ASSERT(nbno > sbno);
+		}
+	}
+
+	ASSERT(rcbag_count(rcstack) == 0);
+out_bag:
+	rcbag_free(&rcstack);
+out_cur:
+	xchk_rtgroup_btcur_free(&sc->sr);
+	return error;
+}
+
+/* Retrieve refcountbt data for bulk load. */
+STATIC int
+xrep_rtrefc_get_records(
+	struct xfs_btree_cur		*cur,
+	unsigned int			idx,
+	struct xfs_btree_block		*block,
+	unsigned int			nr_wanted,
+	void				*priv)
+{
+	struct xrep_rtrefc		*rr = priv;
+	union xfs_btree_rec		*block_rec;
+	unsigned int			loaded;
+	int				error;
+
+	for (loaded = 0; loaded < nr_wanted; loaded++, idx++) {
+		error = xfarray_load(rr->refcount_records, rr->array_cur++,
+				&cur->bc_rec.rc);
+		if (error)
+			return error;
+
+		block_rec = xfs_btree_rec_addr(cur, idx, block);
+		cur->bc_ops->init_rec_from_cur(cur, block_rec);
+	}
+
+	return loaded;
+}
+
+/* Feed one of the new btree blocks to the bulk loader. */
+STATIC int
+xrep_rtrefc_claim_block(
+	struct xfs_btree_cur	*cur,
+	union xfs_btree_ptr	*ptr,
+	void			*priv)
+{
+	struct xrep_rtrefc	*rr = priv;
+
+	return xrep_newbt_claim_block(cur, &rr->new_btree, ptr);
+}
+
+/* Figure out how much space we need to create the incore btree root block. */
+STATIC size_t
+xrep_rtrefc_iroot_size(
+	struct xfs_btree_cur	*cur,
+	unsigned int		level,
+	unsigned int		nr_this_level,
+	void			*priv)
+{
+	return xfs_rtrefcount_broot_space_calc(cur->bc_mp, level,
+			nr_this_level);
+}
+
+/*
+ * Use the collected refcount information to stage a new rt refcount btree.  If
+ * this is successful we'll return with the new btree root information logged
+ * to the repair transaction but not yet committed.
+ */
+STATIC int
+xrep_rtrefc_build_new_tree(
+	struct xrep_rtrefc	*rr)
+{
+	struct xfs_scrub	*sc = rr->sc;
+	struct xfs_rtgroup	*rtg = sc->sr.rtg;
+	struct xfs_btree_cur	*refc_cur;
+	int			error;
+
+	error = xrep_rtrefc_sort_records(rr);
+	if (error)
+		return error;
+
+	/*
+	 * Prepare to construct the new btree by reserving disk space for the
+	 * new btree and setting up all the accounting information we'll need
+	 * to root the new btree while it's under construction and before we
+	 * attach it to the realtime refcount inode.
+	 */
+	error = xrep_newbt_init_metadir_inode(&rr->new_btree, sc);
+	if (error)
+		return error;
+
+	rr->new_btree.bload.get_records = xrep_rtrefc_get_records;
+	rr->new_btree.bload.claim_block = xrep_rtrefc_claim_block;
+	rr->new_btree.bload.iroot_size = xrep_rtrefc_iroot_size;
+
+	refc_cur = xfs_rtrefcountbt_init_cursor(NULL, rtg);
+	xfs_btree_stage_ifakeroot(refc_cur, &rr->new_btree.ifake);
+
+	/* Compute how many blocks we'll need. */
+	error = xfs_btree_bload_compute_geometry(refc_cur, &rr->new_btree.bload,
+			xfarray_length(rr->refcount_records));
+	if (error)
+		goto err_cur;
+
+	/* Last chance to abort before we start committing fixes. */
+	if (xchk_should_terminate(sc, &error))
+		goto err_cur;
+
+	/*
+	 * Guess how many blocks we're going to need to rebuild an entire
+	 * rtrefcountbt from the number of extents we found, and pump up our
+	 * transaction to have sufficient block reservation.  We're allowed
+	 * to exceed quota to repair inconsistent metadata, though this is
+	 * unlikely.
+	 */
+	error = xfs_trans_reserve_more_inode(sc->tp, rtg_refcount(rtg),
+			rr->new_btree.bload.nr_blocks, 0, true);
+	if (error)
+		goto err_cur;
+
+	/* Reserve the space we'll need for the new btree. */
+	error = xrep_newbt_alloc_blocks(&rr->new_btree,
+			rr->new_btree.bload.nr_blocks);
+	if (error)
+		goto err_cur;
+
+	/* Add all observed refcount records. */
+	rr->new_btree.ifake.if_fork->if_format = XFS_DINODE_FMT_META_BTREE;
+	rr->array_cur = XFARRAY_CURSOR_INIT;
+	error = xfs_btree_bload(refc_cur, &rr->new_btree.bload, rr);
+	if (error)
+		goto err_cur;
+
+	/*
+	 * Install the new rtrefc btree in the inode.  After this point the old
+	 * btree is no longer accessible, the new tree is live, and we can
+	 * delete the cursor.
+	 */
+	xfs_rtrefcountbt_commit_staged_btree(refc_cur, sc->tp);
+	xrep_inode_set_nblocks(rr->sc, rr->new_btree.ifake.if_blocks);
+	xfs_btree_del_cursor(refc_cur, 0);
+
+	/* Dispose of any unused blocks and the accounting information. */
+	error = xrep_newbt_commit(&rr->new_btree);
+	if (error)
+		return error;
+
+	return xrep_roll_trans(sc);
+err_cur:
+	xfs_btree_del_cursor(refc_cur, error);
+	xrep_newbt_cancel(&rr->new_btree);
+	return error;
+}
+
+/*
+ * Now that we've logged the roots of the new btrees, invalidate all of the
+ * old blocks and free them.
+ */
+STATIC int
+xrep_rtrefc_remove_old_tree(
+	struct xrep_rtrefc	*rr)
+{
+	int			error;
+
+	/*
+	 * Free all the extents that were allocated to the former rtrefcountbt
+	 * and aren't cross-linked with something else.
+	 */
+	error = xrep_reap_metadir_fsblocks(rr->sc,
+			&rr->old_rtrefcountbt_blocks);
+	if (error)
+		return error;
+
+	/*
+	 * Ensure the proper reservation for the rtrefcount inode so that we
+	 * don't fail to expand the btree.
+	 */
+	return xrep_reset_metafile_resv(rr->sc);
+}
+
+/* Rebuild the rt refcount btree. */
+int
+xrep_rtrefcountbt(
+	struct xfs_scrub	*sc)
+{
+	struct xrep_rtrefc	*rr;
+	struct xfs_mount	*mp = sc->mp;
+	char			*descr;
+	int			error;
+
+	/* We require the rmapbt to rebuild anything. */
+	if (!xfs_has_rtrmapbt(mp))
+		return -EOPNOTSUPP;
+
+	/* Make sure any problems with the fork are fixed. */
+	error = xrep_metadata_inode_forks(sc);
+	if (error)
+		return error;
+
+	rr = kzalloc(sizeof(struct xrep_rtrefc), XCHK_GFP_FLAGS);
+	if (!rr)
+		return -ENOMEM;
+	rr->sc = sc;
+
+	/* Set up enough storage to handle one refcount record per rt extent. */
+	descr = xchk_xfile_ag_descr(sc, "reference count records");
+	error = xfarray_create(descr, mp->m_sb.sb_rextents,
+			sizeof(struct xfs_refcount_irec),
+			&rr->refcount_records);
+	kfree(descr);
+	if (error)
+		goto out_rr;
+
+	/* Collect all reference counts. */
+	xfsb_bitmap_init(&rr->old_rtrefcountbt_blocks);
+	error = xrep_rtrefc_find_refcounts(rr);
+	if (error)
+		goto out_bitmap;
+
+	xfs_trans_ijoin(sc->tp, sc->ip, 0);
+
+	/* Rebuild the refcount information. */
+	error = xrep_rtrefc_build_new_tree(rr);
+	if (error)
+		goto out_bitmap;
+
+	/* Kill the old tree. */
+	error = xrep_rtrefc_remove_old_tree(rr);
+	if (error)
+		goto out_bitmap;
+
+out_bitmap:
+	xfsb_bitmap_destroy(&rr->old_rtrefcountbt_blocks);
+	xfarray_destroy(rr->refcount_records);
+out_rr:
+	kfree(rr);
+	return error;
+}
diff --git a/fs/xfs/scrub/rtrmap.c b/fs/xfs/scrub/rtrmap.c
index 300a1e85b3d6..12989fe80e8b 100644
--- a/fs/xfs/scrub/rtrmap.c
+++ b/fs/xfs/scrub/rtrmap.c
@@ -22,6 +22,7 @@
 #include "xfs_rtalloc.h"
 #include "xfs_rtgroup.h"
 #include "xfs_metafile.h"
+#include "xfs_refcount.h"
 #include "scrub/xfs_scrub.h"
 #include "scrub/scrub.h"
 #include "scrub/common.h"
@@ -77,6 +78,18 @@ struct xchk_rtrmap {
 	struct xfs_rmap_irec	prev_rec;
 };
 
+static inline bool
+xchk_rtrmapbt_is_shareable(
+	struct xfs_scrub		*sc,
+	const struct xfs_rmap_irec	*irec)
+{
+	if (!xfs_has_rtreflink(sc->mp))
+		return false;
+	if (irec->rm_flags & XFS_RMAP_UNWRITTEN)
+		return false;
+	return true;
+}
+
 /* Flag failures for records that overlap but cannot. */
 STATIC void
 xchk_rtrmapbt_check_overlapping(
@@ -98,7 +111,10 @@ xchk_rtrmapbt_check_overlapping(
 	if (pnext <= irec->rm_startblock)
 		goto set_prev;
 
-	xchk_btree_set_corrupt(bs->sc, bs->cur, 0);
+	/* Overlap is only allowed if both records are data fork mappings. */
+	if (!xchk_rtrmapbt_is_shareable(bs->sc, &cr->overlap_rec) ||
+	    !xchk_rtrmapbt_is_shareable(bs->sc, irec))
+		xchk_btree_set_corrupt(bs->sc, bs->cur, 0);
 
 	/* Save whichever rmap record extends furthest. */
 	inext = irec->rm_startblock + irec->rm_blockcount;
@@ -149,6 +165,37 @@ xchk_rtrmapbt_check_mergeable(
 	memcpy(&cr->prev_rec, irec, sizeof(struct xfs_rmap_irec));
 }
 
+/* Cross-reference a rmap against the refcount btree. */
+STATIC void
+xchk_rtrmapbt_xref_rtrefc(
+	struct xfs_scrub	*sc,
+	struct xfs_rmap_irec	*irec)
+{
+	xfs_rgblock_t		fbno;
+	xfs_extlen_t		flen;
+	bool			is_inode;
+	bool			is_bmbt;
+	bool			is_attr;
+	bool			is_unwritten;
+	int			error;
+
+	if (!sc->sr.refc_cur || xchk_skip_xref(sc->sm))
+		return;
+
+	is_inode = !XFS_RMAP_NON_INODE_OWNER(irec->rm_owner);
+	is_bmbt = irec->rm_flags & XFS_RMAP_BMBT_BLOCK;
+	is_attr = irec->rm_flags & XFS_RMAP_ATTR_FORK;
+	is_unwritten = irec->rm_flags & XFS_RMAP_UNWRITTEN;
+
+	/* If this is shared, must be a data fork extent. */
+	error = xfs_refcount_find_shared(sc->sr.refc_cur, irec->rm_startblock,
+			irec->rm_blockcount, &fbno, &flen, false);
+	if (!xchk_should_check_xref(sc, &error, &sc->sr.refc_cur))
+		return;
+	if (flen != 0 && (!is_inode || is_attr || is_bmbt || is_unwritten))
+		xchk_btree_xref_set_corrupt(sc, sc->sr.refc_cur, 0);
+}
+
 /* Cross-reference with other metadata. */
 STATIC void
 xchk_rtrmapbt_xref(
@@ -161,6 +208,11 @@ xchk_rtrmapbt_xref(
 	xchk_xref_is_used_rt_space(sc,
 			xfs_rgbno_to_rtb(sc->sr.rtg, irec->rm_startblock),
 			irec->rm_blockcount);
+	if (irec->rm_owner == XFS_RMAP_OWN_COW)
+		xchk_xref_is_cow_staging(sc, irec->rm_startblock,
+				irec->rm_blockcount);
+	else
+		xchk_rtrmapbt_xref_rtrefc(sc, irec);
 }
 
 /* Scrub a realtime rmapbt record. */
diff --git a/fs/xfs/scrub/rtrmap_repair.c b/fs/xfs/scrub/rtrmap_repair.c
index 49de8bc2dd17..f2fdd7a9fc24 100644
--- a/fs/xfs/scrub/rtrmap_repair.c
+++ b/fs/xfs/scrub/rtrmap_repair.c
@@ -30,6 +30,7 @@
 #include "xfs_rtalloc.h"
 #include "xfs_ag.h"
 #include "xfs_rtgroup.h"
+#include "xfs_refcount.h"
 #include "scrub/xfs_scrub.h"
 #include "scrub/scrub.h"
 #include "scrub/common.h"
@@ -38,6 +39,7 @@
 #include "scrub/repair.h"
 #include "scrub/bitmap.h"
 #include "scrub/fsb_bitmap.h"
+#include "scrub/rgb_bitmap.h"
 #include "scrub/xfile.h"
 #include "scrub/xfarray.h"
 #include "scrub/iscan.h"
@@ -423,6 +425,100 @@ xrep_rtrmap_scan_ag(
 	return error;
 }
 
+struct xrep_rtrmap_stash_run {
+	struct xrep_rtrmap	*rr;
+	uint64_t		owner;
+};
+
+static int
+xrep_rtrmap_stash_run(
+	uint32_t			start,
+	uint32_t			len,
+	void				*priv)
+{
+	struct xrep_rtrmap_stash_run	*rsr = priv;
+	struct xrep_rtrmap		*rr = rsr->rr;
+	xfs_rgblock_t			rgbno = start;
+
+	return xrep_rtrmap_stash(rr, rgbno, len, rsr->owner, 0, 0);
+}
+
+/*
+ * Emit rmaps for every extent of bits set in the bitmap.  Caller must ensure
+ * that the ranges are in units of FS blocks.
+ */
+STATIC int
+xrep_rtrmap_stash_bitmap(
+	struct xrep_rtrmap		*rr,
+	struct xrgb_bitmap		*bitmap,
+	const struct xfs_owner_info	*oinfo)
+{
+	struct xrep_rtrmap_stash_run	rsr = {
+		.rr			= rr,
+		.owner			= oinfo->oi_owner,
+	};
+
+	return xrgb_bitmap_walk(bitmap, xrep_rtrmap_stash_run, &rsr);
+}
+
+/* Record a CoW staging extent. */
+STATIC int
+xrep_rtrmap_walk_cowblocks(
+	struct xfs_btree_cur		*cur,
+	const struct xfs_refcount_irec	*irec,
+	void				*priv)
+{
+	struct xrgb_bitmap		*bitmap = priv;
+
+	if (!xfs_refcount_check_domain(irec) ||
+	    irec->rc_domain != XFS_REFC_DOMAIN_COW)
+		return -EFSCORRUPTED;
+
+	return xrgb_bitmap_set(bitmap, irec->rc_startblock,
+			irec->rc_blockcount);
+}
+
+/*
+ * Collect rmaps for the blocks containing the refcount btree, and all CoW
+ * staging extents.
+ */
+STATIC int
+xrep_rtrmap_find_refcount_rmaps(
+	struct xrep_rtrmap	*rr)
+{
+	struct xrgb_bitmap	cow_blocks;		/* COWBIT */
+	struct xfs_refcount_irec low = {
+		.rc_startblock	= 0,
+		.rc_domain	= XFS_REFC_DOMAIN_COW,
+	};
+	struct xfs_refcount_irec high = {
+		.rc_startblock	= -1U,
+		.rc_domain	= XFS_REFC_DOMAIN_COW,
+	};
+	struct xfs_scrub	*sc = rr->sc;
+	int			error;
+
+	if (!xfs_has_rtreflink(sc->mp))
+		return 0;
+
+	xrgb_bitmap_init(&cow_blocks);
+
+	/* Collect rmaps for CoW staging extents. */
+	error = xfs_refcount_query_range(sc->sr.refc_cur, &low, &high,
+			xrep_rtrmap_walk_cowblocks, &cow_blocks);
+	if (error)
+		goto out_bitmap;
+
+	/* Generate rmaps for everything. */
+	error = xrep_rtrmap_stash_bitmap(rr, &cow_blocks, &XFS_RMAP_OINFO_COW);
+	if (error)
+		goto out_bitmap;
+
+out_bitmap:
+	xrgb_bitmap_destroy(&cow_blocks);
+	return error;
+}
+
 /* Count and check all collected records. */
 STATIC int
 xrep_rtrmap_check_record(
@@ -460,6 +556,13 @@ xrep_rtrmap_find_rmaps(
 			return error;
 	}
 
+	/* Find CoW staging extents. */
+	xrep_rtgroup_btcur_init(sc, &sc->sr);
+	error = xrep_rtrmap_find_refcount_rmaps(rr);
+	xchk_rtgroup_btcur_free(&sc->sr);
+	if (error)
+		return error;
+
 	/*
 	 * Set up for a potentially lengthy filesystem scan by reducing our
 	 * transaction resource usage for the duration.  Specifically:
diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c
index 16da054b2eb0..7567dd5cad14 100644
--- a/fs/xfs/scrub/scrub.c
+++ b/fs/xfs/scrub/scrub.c
@@ -467,6 +467,13 @@ static const struct xchk_meta_ops meta_scrub_ops[] = {
 		.has	= xfs_has_rtrmapbt,
 		.repair	= xrep_rtrmapbt,
 	},
+	[XFS_SCRUB_TYPE_RTREFCBT] = {	/* realtime refcountbt */
+		.type	= ST_RTGROUP,
+		.setup	= xchk_setup_rtrefcountbt,
+		.scrub	= xchk_rtrefcountbt,
+		.has	= xfs_has_rtreflink,
+		.repair	= xrep_rtrefcountbt,
+	},
 };
 
 static int
diff --git a/fs/xfs/scrub/scrub.h b/fs/xfs/scrub/scrub.h
index cba4e89a3a62..a1086f1f06d0 100644
--- a/fs/xfs/scrub/scrub.h
+++ b/fs/xfs/scrub/scrub.h
@@ -129,6 +129,7 @@ struct xchk_rt {
 
 	/* rtgroup btrees */
 	struct xfs_btree_cur	*rmap_cur;
+	struct xfs_btree_cur	*refc_cur;
 };
 
 struct xfs_scrub {
@@ -284,11 +285,13 @@ int xchk_rtbitmap(struct xfs_scrub *sc);
 int xchk_rtsummary(struct xfs_scrub *sc);
 int xchk_rgsuperblock(struct xfs_scrub *sc);
 int xchk_rtrmapbt(struct xfs_scrub *sc);
+int xchk_rtrefcountbt(struct xfs_scrub *sc);
 #else
 # define xchk_rtbitmap		xchk_nothing
 # define xchk_rtsummary		xchk_nothing
 # define xchk_rgsuperblock	xchk_nothing
 # define xchk_rtrmapbt		xchk_nothing
+# define xchk_rtrefcountbt	xchk_nothing
 #endif
 #ifdef CONFIG_XFS_QUOTA
 int xchk_quota(struct xfs_scrub *sc);
@@ -328,11 +331,20 @@ void xchk_xref_has_rt_owner(struct xfs_scrub *sc, xfs_rgblock_t rgbno,
 		xfs_extlen_t len);
 void xchk_xref_is_only_rt_owned_by(struct xfs_scrub *sc, xfs_rgblock_t rgbno,
 		xfs_extlen_t len, const struct xfs_owner_info *oinfo);
+void xchk_xref_is_rt_cow_staging(struct xfs_scrub *sc, xfs_rgblock_t rgbno,
+		xfs_extlen_t len);
+void xchk_xref_is_not_rt_shared(struct xfs_scrub *sc, xfs_rgblock_t rgbno,
+		xfs_extlen_t len);
+void xchk_xref_is_not_rt_cow_staging(struct xfs_scrub *sc, xfs_rgblock_t rgbno,
+		xfs_extlen_t len);
 #else
 # define xchk_xref_is_used_rt_space(sc, rtbno, len) do { } while (0)
 # define xchk_xref_has_no_rt_owner(sc, rtbno, len) do { } while (0)
 # define xchk_xref_has_rt_owner(sc, rtbno, len) do { } while (0)
 # define xchk_xref_is_only_rt_owned_by(sc, bno, len, oinfo) do { } while (0)
+# define xchk_xref_is_rt_cow_staging(sc, bno, len) do { } while (0)
+# define xchk_xref_is_not_rt_shared(sc, bno, len) do { } while (0)
+# define xchk_xref_is_not_rt_cow_staging(sc, bno, len) do { } while (0)
 #endif
 
 #endif	/* __XFS_SCRUB_SCRUB_H__ */
diff --git a/fs/xfs/scrub/stats.c b/fs/xfs/scrub/stats.c
index eb6bb170c902..f8a37ea97791 100644
--- a/fs/xfs/scrub/stats.c
+++ b/fs/xfs/scrub/stats.c
@@ -83,6 +83,7 @@ static const char *name_map[XFS_SCRUB_TYPE_NR] = {
 	[XFS_SCRUB_TYPE_METAPATH]	= "metapath",
 	[XFS_SCRUB_TYPE_RGSUPER]	= "rgsuper",
 	[XFS_SCRUB_TYPE_RTRMAPBT]	= "rtrmapbt",
+	[XFS_SCRUB_TYPE_RTREFCBT]	= "rtrefcountbt",
 };
 
 /* Format the scrub stats into a text buffer, similar to pcp style. */
diff --git a/fs/xfs/scrub/trace.h b/fs/xfs/scrub/trace.h
index fb86b746bc17..d7c4ced47c15 100644
--- a/fs/xfs/scrub/trace.h
+++ b/fs/xfs/scrub/trace.h
@@ -77,6 +77,7 @@ TRACE_DEFINE_ENUM(XFS_SCRUB_TYPE_BARRIER);
 TRACE_DEFINE_ENUM(XFS_SCRUB_TYPE_METAPATH);
 TRACE_DEFINE_ENUM(XFS_SCRUB_TYPE_RGSUPER);
 TRACE_DEFINE_ENUM(XFS_SCRUB_TYPE_RTRMAPBT);
+TRACE_DEFINE_ENUM(XFS_SCRUB_TYPE_RTREFCBT);
 
 #define XFS_SCRUB_TYPE_STRINGS \
 	{ XFS_SCRUB_TYPE_PROBE,		"probe" }, \
@@ -111,7 +112,8 @@ TRACE_DEFINE_ENUM(XFS_SCRUB_TYPE_RTRMAPBT);
 	{ XFS_SCRUB_TYPE_BARRIER,	"barrier" }, \
 	{ XFS_SCRUB_TYPE_METAPATH,	"metapath" }, \
 	{ XFS_SCRUB_TYPE_RGSUPER,	"rgsuper" }, \
-	{ XFS_SCRUB_TYPE_RTRMAPBT,	"rtrmapbt" }
+	{ XFS_SCRUB_TYPE_RTRMAPBT,	"rtrmapbt" }, \
+	{ XFS_SCRUB_TYPE_RTREFCBT,	"rtrefcountbt" }
 
 #define XFS_SCRUB_FLAG_STRINGS \
 	{ XFS_SCRUB_IFLAG_REPAIR,		"repair" }, \
@@ -1962,32 +1964,36 @@ DEFINE_XCHK_METAPATH_EVENT(xchk_metapath_lookup);
 #if IS_ENABLED(CONFIG_XFS_ONLINE_REPAIR)
 
 DECLARE_EVENT_CLASS(xrep_extent_class,
-	TP_PROTO(const struct xfs_perag *pag, xfs_agblock_t agbno,
+	TP_PROTO(const struct xfs_group *xg, xfs_agblock_t agbno,
 		 xfs_extlen_t len),
-	TP_ARGS(pag, agbno, len),
+	TP_ARGS(xg, agbno, len),
 	TP_STRUCT__entry(
 		__field(dev_t, dev)
+		__field(enum xfs_group_type, type)
 		__field(xfs_agnumber_t, agno)
 		__field(xfs_agblock_t, agbno)
 		__field(xfs_extlen_t, len)
 	),
 	TP_fast_assign(
-		__entry->dev = pag_mount(pag)->m_super->s_dev;
-		__entry->agno = pag_agno(pag);
+		__entry->dev = xg->xg_mount->m_super->s_dev;
+		__entry->type = xg->xg_type;
+		__entry->agno = xg->xg_gno;
 		__entry->agbno = agbno;
 		__entry->len = len;
 	),
-	TP_printk("dev %d:%d agno 0x%x agbno 0x%x fsbcount 0x%x",
+	TP_printk("dev %d:%d %sno 0x%x %sbno 0x%x fsbcount 0x%x",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __print_symbolic(__entry->type, XG_TYPE_STRINGS),
 		  __entry->agno,
+		  __print_symbolic(__entry->type, XG_TYPE_STRINGS),
 		  __entry->agbno,
 		  __entry->len)
 );
 #define DEFINE_REPAIR_EXTENT_EVENT(name) \
 DEFINE_EVENT(xrep_extent_class, name, \
-	TP_PROTO(const struct xfs_perag *pag, xfs_agblock_t agbno, \
+	TP_PROTO(const struct xfs_group *xg, xfs_agblock_t agbno, \
 		 xfs_extlen_t len), \
-	TP_ARGS(pag, agbno, len))
+	TP_ARGS(xg, agbno, len))
 DEFINE_REPAIR_EXTENT_EVENT(xreap_dispose_unmap_extent);
 DEFINE_REPAIR_EXTENT_EVENT(xreap_dispose_free_extent);
 DEFINE_REPAIR_EXTENT_EVENT(xreap_agextent_binval);
@@ -1995,35 +2001,39 @@ DEFINE_REPAIR_EXTENT_EVENT(xreap_bmapi_binval);
 DEFINE_REPAIR_EXTENT_EVENT(xrep_agfl_insert);
 
 DECLARE_EVENT_CLASS(xrep_reap_find_class,
-	TP_PROTO(const struct xfs_perag *pag, xfs_agblock_t agbno,
+	TP_PROTO(const struct xfs_group *xg, xfs_agblock_t agbno,
 		 xfs_extlen_t len, bool crosslinked),
-	TP_ARGS(pag, agbno, len, crosslinked),
+	TP_ARGS(xg, agbno, len, crosslinked),
 	TP_STRUCT__entry(
 		__field(dev_t, dev)
+		__field(enum xfs_group_type, type)
 		__field(xfs_agnumber_t, agno)
 		__field(xfs_agblock_t, agbno)
 		__field(xfs_extlen_t, len)
 		__field(bool, crosslinked)
 	),
 	TP_fast_assign(
-		__entry->dev = pag_mount(pag)->m_super->s_dev;
-		__entry->agno = pag_agno(pag);
+		__entry->dev = xg->xg_mount->m_super->s_dev;
+		__entry->type = xg->xg_type;
+		__entry->agno = xg->xg_gno;
 		__entry->agbno = agbno;
 		__entry->len = len;
 		__entry->crosslinked = crosslinked;
 	),
-	TP_printk("dev %d:%d agno 0x%x agbno 0x%x fsbcount 0x%x crosslinked %d",
+	TP_printk("dev %d:%d %sno 0x%x %sbno 0x%x fsbcount 0x%x crosslinked %d",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __print_symbolic(__entry->type, XG_TYPE_STRINGS),
 		  __entry->agno,
+		  __print_symbolic(__entry->type, XG_TYPE_STRINGS),
 		  __entry->agbno,
 		  __entry->len,
 		  __entry->crosslinked ? 1 : 0)
 );
 #define DEFINE_REPAIR_REAP_FIND_EVENT(name) \
 DEFINE_EVENT(xrep_reap_find_class, name, \
-	TP_PROTO(const struct xfs_perag *pag, xfs_agblock_t agbno, \
+	TP_PROTO(const struct xfs_group *xg, xfs_agblock_t agbno, \
 		 xfs_extlen_t len, bool crosslinked), \
-	TP_ARGS(pag, agbno, len, crosslinked))
+	TP_ARGS(xg, agbno, len, crosslinked))
 DEFINE_REPAIR_REAP_FIND_EVENT(xreap_agextent_select);
 DEFINE_REPAIR_REAP_FIND_EVENT(xreap_bmapi_select);
 
@@ -2114,29 +2124,33 @@ TRACE_EVENT(xrep_ibt_found,
 )
 
 TRACE_EVENT(xrep_refc_found,
-	TP_PROTO(const struct xfs_perag *pag,
+	TP_PROTO(const struct xfs_group *xg,
 		 const struct xfs_refcount_irec *rec),
-	TP_ARGS(pag, rec),
+	TP_ARGS(xg, rec),
 	TP_STRUCT__entry(
 		__field(dev_t, dev)
 		__field(xfs_agnumber_t, agno)
 		__field(enum xfs_refc_domain, domain)
+		__field(enum xfs_group_type, type)
 		__field(xfs_agblock_t, startblock)
 		__field(xfs_extlen_t, blockcount)
 		__field(xfs_nlink_t, refcount)
 	),
 	TP_fast_assign(
-		__entry->dev = pag_mount(pag)->m_super->s_dev;
-		__entry->agno = pag_agno(pag);
+		__entry->dev = xg->xg_mount->m_super->s_dev;
+		__entry->agno = xg->xg_gno;
+		__entry->type = xg->xg_type;
 		__entry->domain = rec->rc_domain;
 		__entry->startblock = rec->rc_startblock;
 		__entry->blockcount = rec->rc_blockcount;
 		__entry->refcount = rec->rc_refcount;
 	),
-	TP_printk("dev %d:%d agno 0x%x dom %s agbno 0x%x fsbcount 0x%x refcount %u",
+	TP_printk("dev %d:%d %sno 0x%x dom %s %sbno 0x%x fsbcount 0x%x refcount %u",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __print_symbolic(__entry->type, XG_TYPE_STRINGS),
 		  __entry->agno,
 		  __print_symbolic(__entry->domain, XFS_REFC_DOMAIN_STRINGS),
+		  __print_symbolic(__entry->type, XG_TYPE_STRINGS),
 		  __entry->startblock,
 		  __entry->blockcount,
 		  __entry->refcount)
diff --git a/fs/xfs/xfs_buf_item_recover.c b/fs/xfs/xfs_buf_item_recover.c
index 4f2e4ea29e1f..b05d5b81f642 100644
--- a/fs/xfs/xfs_buf_item_recover.c
+++ b/fs/xfs/xfs_buf_item_recover.c
@@ -271,6 +271,9 @@ xlog_recover_validate_buf_type(
 		case XFS_REFC_CRC_MAGIC:
 			bp->b_ops = &xfs_refcountbt_buf_ops;
 			break;
+		case XFS_RTREFC_CRC_MAGIC:
+			bp->b_ops = &xfs_rtrefcountbt_buf_ops;
+			break;
 		default:
 			warnmsg = "Bad btree block magic!";
 			break;
@@ -859,6 +862,7 @@ xlog_recover_get_buf_lsn(
 		break;
 	}
 	case XFS_RTRMAP_CRC_MAGIC:
+	case XFS_RTREFC_CRC_MAGIC:
 	case XFS_BMAP_CRC_MAGIC:
 	case XFS_BMAP_MAGIC: {
 		struct xfs_btree_block *btb = blk;
diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c
index 3e3ef16f65a3..1dbd2d75f7ae 100644
--- a/fs/xfs/xfs_fsmap.c
+++ b/fs/xfs/xfs_fsmap.c
@@ -27,6 +27,7 @@
 #include "xfs_ag.h"
 #include "xfs_rtgroup.h"
 #include "xfs_rtrmap_btree.h"
+#include "xfs_rtrefcount_btree.h"
 
 /* Convert an xfs_fsmap to an fsmap. */
 static void
@@ -212,21 +213,20 @@ xfs_getfsmap_is_shared(
 	struct xfs_mount		*mp = tp->t_mountp;
 	struct xfs_btree_cur		*cur;
 	xfs_agblock_t			fbno;
-	xfs_extlen_t			flen;
+	xfs_extlen_t			flen = 0;
 	int				error;
 
 	*stat = false;
-	if (!xfs_has_reflink(mp))
-		return 0;
-	/* rt files will have no perag structure */
-	if (!info->group)
+	if (!xfs_has_reflink(mp) || !info->group)
 		return 0;
 
-	/* Are there any shared blocks here? */
-	flen = 0;
-	cur = xfs_refcountbt_init_cursor(mp, tp, info->agf_bp,
-			to_perag(info->group));
+	if (info->group->xg_type == XG_TYPE_RTG)
+		cur = xfs_rtrefcountbt_init_cursor(tp, to_rtg(info->group));
+	else
+		cur = xfs_refcountbt_init_cursor(mp, tp, info->agf_bp,
+				to_perag(info->group));
 
+	/* Are there any shared blocks here? */
 	error = xfs_refcount_find_shared(cur, frec->rec_key,
 			XFS_BB_TO_FSBT(mp, frec->len_daddr), &fbno, &flen,
 			false);
@@ -863,7 +863,7 @@ xfs_getfsmap_rtdev_rmapbt_query(
 	struct xfs_rtgroup		*rtg = to_rtg(info->group);
 
 	/* Query the rtrmapbt */
-	xfs_rtgroup_lock(rtg, XFS_RTGLOCK_RMAP);
+	xfs_rtgroup_lock(rtg, XFS_RTGLOCK_RMAP | XFS_RTGLOCK_REFCOUNT);
 	*curpp = xfs_rtrmapbt_init_cursor(tp, rtg);
 	return xfs_rmap_query_range(*curpp, &info->low, &info->high,
 			xfs_getfsmap_rtdev_rmapbt_helper, info);
@@ -950,7 +950,8 @@ xfs_getfsmap_rtdev_rmapbt(
 
 		if (bt_cur) {
 			xfs_rtgroup_unlock(to_rtg(bt_cur->bc_group),
-					XFS_RTGLOCK_RMAP);
+					XFS_RTGLOCK_RMAP |
+					XFS_RTGLOCK_REFCOUNT);
 			xfs_btree_del_cursor(bt_cur, XFS_BTREE_NOERROR);
 			bt_cur = NULL;
 		}
@@ -988,7 +989,7 @@ xfs_getfsmap_rtdev_rmapbt(
 
 	if (bt_cur) {
 		xfs_rtgroup_unlock(to_rtg(bt_cur->bc_group),
-				XFS_RTGLOCK_RMAP);
+				XFS_RTGLOCK_RMAP | XFS_RTGLOCK_REFCOUNT);
 		xfs_btree_del_cursor(bt_cur, error < 0 ? XFS_BTREE_ERROR :
 							 XFS_BTREE_NOERROR);
 	}
diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index 9df5a09c0acd..455298503d01 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -23,6 +23,7 @@
 #include "xfs_trace.h"
 #include "xfs_rtalloc.h"
 #include "xfs_rtrmap_btree.h"
+#include "xfs_rtrefcount_btree.h"
 
 /*
  * Write new AG headers to disk. Non-transactional, but need to be
@@ -231,6 +232,7 @@ xfs_growfs_data_private(
 
 		/* Compute new maxlevels for rt btrees. */
 		xfs_rtrmapbt_compute_maxlevels(mp);
+		xfs_rtrefcountbt_compute_maxlevels(mp);
 	}
 
 	return error;
diff --git a/fs/xfs/xfs_health.c b/fs/xfs/xfs_health.c
index d438c3c001c8..7c541fb373d5 100644
--- a/fs/xfs/xfs_health.c
+++ b/fs/xfs/xfs_health.c
@@ -448,6 +448,7 @@ static const struct ioctl_sick_map rtgroup_map[] = {
 	{ XFS_SICK_RG_BITMAP,	XFS_RTGROUP_GEOM_SICK_BITMAP },
 	{ XFS_SICK_RG_SUMMARY,	XFS_RTGROUP_GEOM_SICK_SUMMARY },
 	{ XFS_SICK_RG_RMAPBT,	XFS_RTGROUP_GEOM_SICK_RMAPBT },
+	{ XFS_SICK_RG_REFCNTBT,	XFS_RTGROUP_GEOM_SICK_REFCNTBT },
 };
 
 /* Fill out rtgroup geometry health info. */
diff --git a/fs/xfs/xfs_inode_item.c b/fs/xfs/xfs_inode_item.c
index a174f64b8bb2..70283c6419fd 100644
--- a/fs/xfs/xfs_inode_item.c
+++ b/fs/xfs/xfs_inode_item.c
@@ -157,6 +157,20 @@ xfs_inode_item_precommit(
 	if (flags & XFS_ILOG_IVERSION)
 		flags = ((flags & ~XFS_ILOG_IVERSION) | XFS_ILOG_CORE);
 
+	/*
+	 * Inode verifiers do not check that the CoW extent size hint is an
+	 * integer multiple of the rt extent size on a directory with both
+	 * rtinherit and cowextsize flags set.  If we're logging a directory
+	 * that is misconfigured in this way, clear the hint.
+	 */
+	if ((ip->i_diflags & XFS_DIFLAG_RTINHERIT) &&
+	    (ip->i_diflags2 & XFS_DIFLAG2_COWEXTSIZE) &&
+	    xfs_extlen_to_rtxmod(ip->i_mount, ip->i_cowextsize) > 0) {
+		ip->i_diflags2 &= ~XFS_DIFLAG2_COWEXTSIZE;
+		ip->i_cowextsize = 0;
+		flags |= XFS_ILOG_CORE;
+	}
+
 	if (!iip->ili_item.li_buf) {
 		struct xfs_buf	*bp;
 		int		error;
diff --git a/fs/xfs/xfs_inode_item_recover.c b/fs/xfs/xfs_inode_item_recover.c
index 5de1d3563b76..f3bfb814378c 100644
--- a/fs/xfs/xfs_inode_item_recover.c
+++ b/fs/xfs/xfs_inode_item_recover.c
@@ -23,6 +23,7 @@
 #include "xfs_icache.h"
 #include "xfs_bmap_btree.h"
 #include "xfs_rtrmap_btree.h"
+#include "xfs_rtrefcount_btree.h"
 
 STATIC void
 xlog_recover_inode_ra_pass2(
@@ -286,6 +287,9 @@ xlog_recover_inode_dbroot(
 		case XFS_METAFILE_RTRMAP:
 			xfs_rtrmapbt_to_disk(mp, src, len, dfork, dsize);
 			return 0;
+		case XFS_METAFILE_RTREFCOUNT:
+			xfs_rtrefcountbt_to_disk(mp, src, len, dfork, dsize);
+			return 0;
 		default:
 			ASSERT(0);
 			return -EFSCORRUPTED;
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 0789c18aaa18..726282e74d54 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -469,8 +469,21 @@ xfs_fill_fsxattr(
 		}
 	}
 
-	if (ip->i_diflags2 & XFS_DIFLAG2_COWEXTSIZE)
-		fa->fsx_cowextsize = XFS_FSB_TO_B(mp, ip->i_cowextsize);
+	if (ip->i_diflags2 & XFS_DIFLAG2_COWEXTSIZE) {
+		/*
+		 * Don't let a misaligned CoW extent size hint on a directory
+		 * escape to userspace if it won't pass the setattr checks
+		 * later.
+		 */
+		if ((ip->i_diflags & XFS_DIFLAG_RTINHERIT) &&
+		    ip->i_cowextsize % mp->m_sb.sb_rextsize > 0) {
+			fa->fsx_xflags &= ~FS_XFLAG_COWEXTSIZE;
+			fa->fsx_cowextsize = 0;
+		} else {
+			fa->fsx_cowextsize = XFS_FSB_TO_B(mp, ip->i_cowextsize);
+		}
+	}
+
 	fa->fsx_projid = ip->i_projid;
 	if (ifp && !xfs_need_iread_extents(ifp))
 		fa->fsx_nextents = xfs_iext_count(ifp);
@@ -541,10 +554,6 @@ xfs_ioctl_setattr_xflags(
 		if (mp->m_sb.sb_rblocks == 0 || mp->m_sb.sb_rextsize == 0 ||
 		    xfs_extlen_to_rtxmod(mp, ip->i_extsize))
 			return -EINVAL;
-
-		/* Clear reflink if we are actually able to set the rt flag. */
-		if (xfs_is_reflink_inode(ip))
-			ip->i_diflags2 &= ~XFS_DIFLAG2_REFLINK;
 	}
 
 	/* diflags2 only valid for v3 inodes. */
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 5c95c97519c7..b3c27dbccce8 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -1822,6 +1822,8 @@ static const struct xlog_recover_item_ops *xlog_recover_item_ops[] = {
 	&xlog_rtefd_item_ops,
 	&xlog_rtrui_item_ops,
 	&xlog_rtrud_item_ops,
+	&xlog_rtcui_item_ops,
+	&xlog_rtcud_item_ops,
 };
 
 static const struct xlog_recover_item_ops *
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 7b7d21b50d54..477c5262cf91 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -38,6 +38,7 @@
 #include "xfs_metafile.h"
 #include "xfs_rtgroup.h"
 #include "xfs_rtrmap_btree.h"
+#include "xfs_rtrefcount_btree.h"
 #include "scrub/stats.h"
 
 static DEFINE_MUTEX(xfs_uuid_table_mutex);
@@ -656,7 +657,8 @@ static inline void
 xfs_rtbtree_compute_maxlevels(
 	struct xfs_mount	*mp)
 {
-	mp->m_rtbtree_maxlevels = mp->m_rtrmap_maxlevels;
+	mp->m_rtbtree_maxlevels = max(mp->m_rtrmap_maxlevels,
+				      mp->m_rtrefc_maxlevels);
 }
 
 /*
@@ -729,6 +731,7 @@ xfs_mountfs(
 	xfs_rmapbt_compute_maxlevels(mp);
 	xfs_rtrmapbt_compute_maxlevels(mp);
 	xfs_refcountbt_compute_maxlevels(mp);
+	xfs_rtrefcountbt_compute_maxlevels(mp);
 
 	xfs_agbtree_compute_maxlevels(mp);
 	xfs_rtbtree_compute_maxlevels(mp);
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 1bc95fb170db..9a1516080e63 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -162,11 +162,14 @@ typedef struct xfs_mount {
 	uint			m_rtrmap_mnr[2]; /* min rtrmap btree records */
 	uint			m_refc_mxr[2];	/* max refc btree records */
 	uint			m_refc_mnr[2];	/* min refc btree records */
+	uint			m_rtrefc_mxr[2]; /* max rtrefc btree records */
+	uint			m_rtrefc_mnr[2]; /* min rtrefc btree records */
 	uint			m_alloc_maxlevels; /* max alloc btree levels */
 	uint			m_bm_maxlevels[2]; /* max bmap btree levels */
 	uint			m_rmap_maxlevels; /* max rmap btree levels */
 	uint			m_rtrmap_maxlevels; /* max rtrmap btree level */
 	uint			m_refc_maxlevels; /* max refcount btree level */
+	uint			m_rtrefc_maxlevels; /* max rtrefc btree level */
 	unsigned int		m_agbtree_maxlevels; /* max level of all AG btrees */
 	unsigned int		m_rtbtree_maxlevels; /* max level of all rt btrees */
 	xfs_extlen_t		m_ag_prealloc_blocks; /* reserved ag blocks */
@@ -408,6 +411,12 @@ static inline bool xfs_has_rtrmapbt(struct xfs_mount *mp)
 	       xfs_has_rmapbt(mp);
 }
 
+static inline bool xfs_has_rtreflink(struct xfs_mount *mp)
+{
+	return xfs_has_metadir(mp) && xfs_has_realtime(mp) &&
+	       xfs_has_reflink(mp);
+}
+
 /*
  * Some features are always on for v5 file systems, allow the compiler to
  * eliminiate dead code when building without v4 support.
diff --git a/fs/xfs/xfs_refcount_item.c b/fs/xfs/xfs_refcount_item.c
index bede1c96c330..fe2d7aab8554 100644
--- a/fs/xfs/xfs_refcount_item.c
+++ b/fs/xfs/xfs_refcount_item.c
@@ -23,6 +23,7 @@
 #include "xfs_ag.h"
 #include "xfs_btree.h"
 #include "xfs_trace.h"
+#include "xfs_rtgroup.h"
 
 struct kmem_cache	*xfs_cui_cache;
 struct kmem_cache	*xfs_cud_cache;
@@ -94,8 +95,9 @@ xfs_cui_item_format(
 
 	ASSERT(atomic_read(&cuip->cui_next_extent) ==
 			cuip->cui_format.cui_nextents);
+	ASSERT(lip->li_type == XFS_LI_CUI || lip->li_type == XFS_LI_CUI_RT);
 
-	cuip->cui_format.cui_type = XFS_LI_CUI;
+	cuip->cui_format.cui_type = lip->li_type;
 	cuip->cui_format.cui_size = 1;
 
 	xlog_copy_iovec(lv, &vecp, XLOG_REG_TYPE_CUI_FORMAT, &cuip->cui_format,
@@ -138,12 +140,14 @@ xfs_cui_item_release(
 STATIC struct xfs_cui_log_item *
 xfs_cui_init(
 	struct xfs_mount		*mp,
+	unsigned short			item_type,
 	uint				nextents)
-
 {
 	struct xfs_cui_log_item		*cuip;
 
 	ASSERT(nextents > 0);
+	ASSERT(item_type == XFS_LI_CUI || item_type == XFS_LI_CUI_RT);
+
 	if (nextents > XFS_CUI_MAX_FAST_EXTENTS)
 		cuip = kzalloc(xfs_cui_log_item_sizeof(nextents),
 				GFP_KERNEL | __GFP_NOFAIL);
@@ -151,7 +155,7 @@ xfs_cui_init(
 		cuip = kmem_cache_zalloc(xfs_cui_cache,
 					 GFP_KERNEL | __GFP_NOFAIL);
 
-	xfs_log_item_init(mp, &cuip->cui_item, XFS_LI_CUI, &xfs_cui_item_ops);
+	xfs_log_item_init(mp, &cuip->cui_item, item_type, &xfs_cui_item_ops);
 	cuip->cui_format.cui_nextents = nextents;
 	cuip->cui_format.cui_id = (uintptr_t)(void *)cuip;
 	atomic_set(&cuip->cui_next_extent, 0);
@@ -190,7 +194,9 @@ xfs_cud_item_format(
 	struct xfs_cud_log_item	*cudp = CUD_ITEM(lip);
 	struct xfs_log_iovec	*vecp = NULL;
 
-	cudp->cud_format.cud_type = XFS_LI_CUD;
+	ASSERT(lip->li_type == XFS_LI_CUD || lip->li_type == XFS_LI_CUD_RT);
+
+	cudp->cud_format.cud_type = lip->li_type;
 	cudp->cud_format.cud_size = 1;
 
 	xlog_copy_iovec(lv, &vecp, XLOG_REG_TYPE_CUD_FORMAT, &cudp->cud_format,
@@ -234,6 +240,14 @@ static inline struct xfs_refcount_intent *ci_entry(const struct list_head *e)
 	return list_entry(e, struct xfs_refcount_intent, ri_list);
 }
 
+static inline bool
+xfs_cui_item_isrt(const struct xfs_log_item *lip)
+{
+	ASSERT(lip->li_type == XFS_LI_CUI || lip->li_type == XFS_LI_CUI_RT);
+
+	return lip->li_type == XFS_LI_CUI_RT;
+}
+
 /* Sort refcount intents by AG. */
 static int
 xfs_refcount_update_diff_items(
@@ -282,18 +296,20 @@ xfs_refcount_update_log_item(
 }
 
 static struct xfs_log_item *
-xfs_refcount_update_create_intent(
+__xfs_refcount_update_create_intent(
 	struct xfs_trans		*tp,
 	struct list_head		*items,
 	unsigned int			count,
-	bool				sort)
+	bool				sort,
+	unsigned short			item_type)
 {
 	struct xfs_mount		*mp = tp->t_mountp;
-	struct xfs_cui_log_item		*cuip = xfs_cui_init(mp, count);
+	struct xfs_cui_log_item		*cuip;
 	struct xfs_refcount_intent	*ri;
 
 	ASSERT(count > 0);
 
+	cuip = xfs_cui_init(mp, item_type, count);
 	if (sort)
 		list_sort(mp, items, xfs_refcount_update_diff_items);
 	list_for_each_entry(ri, items, ri_list)
@@ -301,6 +317,23 @@ xfs_refcount_update_create_intent(
 	return &cuip->cui_item;
 }
 
+static struct xfs_log_item *
+xfs_refcount_update_create_intent(
+	struct xfs_trans		*tp,
+	struct list_head		*items,
+	unsigned int			count,
+	bool				sort)
+{
+	return __xfs_refcount_update_create_intent(tp, items, count, sort,
+			XFS_LI_CUI);
+}
+
+static inline unsigned short
+xfs_cud_type_from_cui(const struct xfs_cui_log_item *cuip)
+{
+	return xfs_cui_item_isrt(&cuip->cui_item) ? XFS_LI_CUD_RT : XFS_LI_CUD;
+}
+
 /* Get an CUD so we can process all the deferred refcount updates. */
 static struct xfs_log_item *
 xfs_refcount_update_create_done(
@@ -312,8 +345,8 @@ xfs_refcount_update_create_done(
 	struct xfs_cud_log_item		*cudp;
 
 	cudp = kmem_cache_zalloc(xfs_cud_cache, GFP_KERNEL | __GFP_NOFAIL);
-	xfs_log_item_init(tp->t_mountp, &cudp->cud_item, XFS_LI_CUD,
-			  &xfs_cud_item_ops);
+	xfs_log_item_init(tp->t_mountp, &cudp->cud_item,
+			xfs_cud_type_from_cui(cuip), &xfs_cud_item_ops);
 	cudp->cud_cuip = cuip;
 	cudp->cud_format.cud_cui_id = cuip->cui_format.cui_id;
 
@@ -328,10 +361,20 @@ xfs_refcount_defer_add(
 {
 	struct xfs_mount		*mp = tp->t_mountp;
 
-	trace_xfs_refcount_defer(mp, ri);
+	/*
+	 * Deferred refcount updates for the realtime and data sections must
+	 * use separate transactions to finish deferred work because updates to
+	 * realtime metadata files can lock AGFs to allocate btree blocks and
+	 * we don't want that mixing with the AGF locks taken to finish data
+	 * section updates.
+	 */
+	ri->ri_group = xfs_group_intent_get(mp, ri->ri_startblock,
+			ri->ri_realtime ? XG_TYPE_RTG : XG_TYPE_AG);
 
-	ri->ri_group = xfs_group_intent_get(mp, ri->ri_startblock, XG_TYPE_AG);
-	xfs_defer_add(tp, &ri->ri_list, &xfs_refcount_update_defer_type);
+	trace_xfs_refcount_defer(mp, ri);
+	xfs_defer_add(tp, &ri->ri_list, ri->ri_realtime ?
+			&xfs_rtrefcount_update_defer_type :
+			&xfs_refcount_update_defer_type);
 }
 
 /* Cancel a deferred refcount update. */
@@ -381,7 +424,7 @@ xfs_refcount_finish_one_cleanup(
 		return;
 	agbp = rcur->bc_ag.agbp;
 	xfs_btree_del_cursor(rcur, error);
-	if (error)
+	if (error && agbp)
 		xfs_trans_brelse(tp, agbp);
 }
 
@@ -397,6 +440,7 @@ xfs_refcount_update_abort_intent(
 static inline bool
 xfs_cui_validate_phys(
 	struct xfs_mount		*mp,
+	bool				isrt,
 	struct xfs_phys_extent		*pmap)
 {
 	if (!xfs_has_reflink(mp))
@@ -415,6 +459,9 @@ xfs_cui_validate_phys(
 		return false;
 	}
 
+	if (isrt)
+		return xfs_verify_rtbext(mp, pmap->pe_startblock, pmap->pe_len);
+
 	return xfs_verify_fsbext(mp, pmap->pe_startblock, pmap->pe_len);
 }
 
@@ -422,6 +469,7 @@ static inline void
 xfs_cui_recover_work(
 	struct xfs_mount		*mp,
 	struct xfs_defer_pending	*dfp,
+	bool				isrt,
 	struct xfs_phys_extent		*pmap)
 {
 	struct xfs_refcount_intent	*ri;
@@ -432,7 +480,8 @@ xfs_cui_recover_work(
 	ri->ri_startblock = pmap->pe_startblock;
 	ri->ri_blockcount = pmap->pe_len;
 	ri->ri_group = xfs_group_intent_get(mp, pmap->pe_startblock,
-			XG_TYPE_AG);
+			isrt ? XG_TYPE_RTG : XG_TYPE_AG);
+	ri->ri_realtime = isrt;
 
 	xfs_defer_add_item(dfp, &ri->ri_list);
 }
@@ -451,6 +500,7 @@ xfs_refcount_recover_work(
 	struct xfs_cui_log_item		*cuip = CUI_ITEM(lip);
 	struct xfs_trans		*tp;
 	struct xfs_mount		*mp = lip->li_log->l_mp;
+	bool				isrt = xfs_cui_item_isrt(lip);
 	int				i;
 	int				error = 0;
 
@@ -460,7 +510,7 @@ xfs_refcount_recover_work(
 	 * just toss the CUI.
 	 */
 	for (i = 0; i < cuip->cui_format.cui_nextents; i++) {
-		if (!xfs_cui_validate_phys(mp,
+		if (!xfs_cui_validate_phys(mp, isrt,
 					&cuip->cui_format.cui_extents[i])) {
 			XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp,
 					&cuip->cui_format,
@@ -468,7 +518,8 @@ xfs_refcount_recover_work(
 			return -EFSCORRUPTED;
 		}
 
-		xfs_cui_recover_work(mp, dfp, &cuip->cui_format.cui_extents[i]);
+		xfs_cui_recover_work(mp, dfp, isrt,
+				&cuip->cui_format.cui_extents[i]);
 	}
 
 	/*
@@ -515,10 +566,13 @@ xfs_refcount_relog_intent(
 	struct xfs_phys_extent		*pmap;
 	unsigned int			count;
 
+	ASSERT(intent->li_type == XFS_LI_CUI ||
+	       intent->li_type == XFS_LI_CUI_RT);
+
 	count = CUI_ITEM(intent)->cui_format.cui_nextents;
 	pmap = CUI_ITEM(intent)->cui_format.cui_extents;
 
-	cuip = xfs_cui_init(tp->t_mountp, count);
+	cuip = xfs_cui_init(tp->t_mountp, intent->li_type, count);
 	memcpy(cuip->cui_format.cui_extents, pmap, count * sizeof(*pmap));
 	atomic_set(&cuip->cui_next_extent, count);
 
@@ -538,6 +592,71 @@ const struct xfs_defer_op_type xfs_refcount_update_defer_type = {
 	.relog_intent	= xfs_refcount_relog_intent,
 };
 
+#ifdef CONFIG_XFS_RT
+static struct xfs_log_item *
+xfs_rtrefcount_update_create_intent(
+	struct xfs_trans		*tp,
+	struct list_head		*items,
+	unsigned int			count,
+	bool				sort)
+{
+	return __xfs_refcount_update_create_intent(tp, items, count, sort,
+			XFS_LI_CUI_RT);
+}
+
+/* Process a deferred realtime refcount update. */
+STATIC int
+xfs_rtrefcount_update_finish_item(
+	struct xfs_trans		*tp,
+	struct xfs_log_item		*done,
+	struct list_head		*item,
+	struct xfs_btree_cur		**state)
+{
+	struct xfs_refcount_intent	*ri = ci_entry(item);
+	int				error;
+
+	error = xfs_rtrefcount_finish_one(tp, ri, state);
+
+	/* Did we run out of reservation?  Requeue what we didn't finish. */
+	if (!error && ri->ri_blockcount > 0) {
+		ASSERT(ri->ri_type == XFS_REFCOUNT_INCREASE ||
+		       ri->ri_type == XFS_REFCOUNT_DECREASE);
+		return -EAGAIN;
+	}
+
+	xfs_refcount_update_cancel_item(item);
+	return error;
+}
+
+/* Clean up after calling xfs_rtrefcount_finish_one. */
+STATIC void
+xfs_rtrefcount_finish_one_cleanup(
+	struct xfs_trans	*tp,
+	struct xfs_btree_cur	*rcur,
+	int			error)
+{
+	if (rcur)
+		xfs_btree_del_cursor(rcur, error);
+}
+
+const struct xfs_defer_op_type xfs_rtrefcount_update_defer_type = {
+	.name		= "rtrefcount",
+	.max_items	= XFS_CUI_MAX_FAST_EXTENTS,
+	.create_intent	= xfs_rtrefcount_update_create_intent,
+	.abort_intent	= xfs_refcount_update_abort_intent,
+	.create_done	= xfs_refcount_update_create_done,
+	.finish_item	= xfs_rtrefcount_update_finish_item,
+	.finish_cleanup = xfs_rtrefcount_finish_one_cleanup,
+	.cancel_item	= xfs_refcount_update_cancel_item,
+	.recover_work	= xfs_refcount_recover_work,
+	.relog_intent	= xfs_refcount_relog_intent,
+};
+#else
+const struct xfs_defer_op_type xfs_rtrefcount_update_defer_type = {
+	.name		= "rtrefcount",
+};
+#endif /* CONFIG_XFS_RT */
+
 STATIC bool
 xfs_cui_item_match(
 	struct xfs_log_item	*lip,
@@ -603,7 +722,7 @@ xlog_recover_cui_commit_pass2(
 		return -EFSCORRUPTED;
 	}
 
-	cuip = xfs_cui_init(mp, cui_formatp->cui_nextents);
+	cuip = xfs_cui_init(mp, ITEM_TYPE(item), cui_formatp->cui_nextents);
 	xfs_cui_copy_format(&cuip->cui_format, cui_formatp);
 	atomic_set(&cuip->cui_next_extent, cui_formatp->cui_nextents);
 
@@ -617,6 +736,61 @@ const struct xlog_recover_item_ops xlog_cui_item_ops = {
 	.commit_pass2		= xlog_recover_cui_commit_pass2,
 };
 
+#ifdef CONFIG_XFS_RT
+STATIC int
+xlog_recover_rtcui_commit_pass2(
+	struct xlog			*log,
+	struct list_head		*buffer_list,
+	struct xlog_recover_item	*item,
+	xfs_lsn_t			lsn)
+{
+	struct xfs_mount		*mp = log->l_mp;
+	struct xfs_cui_log_item		*cuip;
+	struct xfs_cui_log_format	*cui_formatp;
+	size_t				len;
+
+	cui_formatp = item->ri_buf[0].i_addr;
+
+	if (item->ri_buf[0].i_len < xfs_cui_log_format_sizeof(0)) {
+		XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp,
+				item->ri_buf[0].i_addr, item->ri_buf[0].i_len);
+		return -EFSCORRUPTED;
+	}
+
+	len = xfs_cui_log_format_sizeof(cui_formatp->cui_nextents);
+	if (item->ri_buf[0].i_len != len) {
+		XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp,
+				item->ri_buf[0].i_addr, item->ri_buf[0].i_len);
+		return -EFSCORRUPTED;
+	}
+
+	cuip = xfs_cui_init(mp, ITEM_TYPE(item), cui_formatp->cui_nextents);
+	xfs_cui_copy_format(&cuip->cui_format, cui_formatp);
+	atomic_set(&cuip->cui_next_extent, cui_formatp->cui_nextents);
+
+	xlog_recover_intent_item(log, &cuip->cui_item, lsn,
+			&xfs_rtrefcount_update_defer_type);
+	return 0;
+}
+#else
+STATIC int
+xlog_recover_rtcui_commit_pass2(
+	struct xlog			*log,
+	struct list_head		*buffer_list,
+	struct xlog_recover_item	*item,
+	xfs_lsn_t			lsn)
+{
+	XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, log->l_mp,
+			item->ri_buf[0].i_addr, item->ri_buf[0].i_len);
+	return -EFSCORRUPTED;
+}
+#endif
+
+const struct xlog_recover_item_ops xlog_rtcui_item_ops = {
+	.item_type		= XFS_LI_CUI_RT,
+	.commit_pass2		= xlog_recover_rtcui_commit_pass2,
+};
+
 /*
  * This routine is called when an CUD format structure is found in a committed
  * transaction in the log. Its purpose is to cancel the corresponding CUI if it
@@ -648,3 +822,33 @@ const struct xlog_recover_item_ops xlog_cud_item_ops = {
 	.item_type		= XFS_LI_CUD,
 	.commit_pass2		= xlog_recover_cud_commit_pass2,
 };
+
+#ifdef CONFIG_XFS_RT
+STATIC int
+xlog_recover_rtcud_commit_pass2(
+	struct xlog			*log,
+	struct list_head		*buffer_list,
+	struct xlog_recover_item	*item,
+	xfs_lsn_t			lsn)
+{
+	struct xfs_cud_log_format	*cud_formatp;
+
+	cud_formatp = item->ri_buf[0].i_addr;
+	if (item->ri_buf[0].i_len != sizeof(struct xfs_cud_log_format)) {
+		XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, log->l_mp,
+				item->ri_buf[0].i_addr, item->ri_buf[0].i_len);
+		return -EFSCORRUPTED;
+	}
+
+	xlog_recover_release_intent(log, XFS_LI_CUI_RT,
+			cud_formatp->cud_cui_id);
+	return 0;
+}
+#else
+# define xlog_recover_rtcud_commit_pass2	xlog_recover_rtcui_commit_pass2
+#endif
+
+const struct xlog_recover_item_ops xlog_rtcud_item_ops = {
+	.item_type		= XFS_LI_CUD_RT,
+	.commit_pass2		= xlog_recover_rtcud_commit_pass2,
+};
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index b11769c009ef..59f7fc16eb80 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -30,6 +30,10 @@
 #include "xfs_ag.h"
 #include "xfs_ag_resv.h"
 #include "xfs_health.h"
+#include "xfs_rtrefcount_btree.h"
+#include "xfs_rtalloc.h"
+#include "xfs_rtgroup.h"
+#include "xfs_metafile.h"
 
 /*
  * Copy on Write of Shared Blocks
@@ -120,38 +124,93 @@
  */
 
 /*
- * Given an AG extent, find the lowest-numbered run of shared blocks
- * within that range and return the range in fbno/flen.  If
- * find_end_of_shared is true, return the longest contiguous extent of
- * shared blocks.  If there are no shared extents, fbno and flen will
- * be set to NULLAGBLOCK and 0, respectively.
+ * Given a file mapping for the data device, find the lowest-numbered run of
+ * shared blocks within that mapping and return it in shared_offset/shared_len.
+ * The offset is relative to the start of irec.
+ *
+ * If find_end_of_shared is true, return the longest contiguous extent of shared
+ * blocks.  If there are no shared extents, shared_offset and shared_len will be
+ * set to 0;
  */
 static int
 xfs_reflink_find_shared(
-	struct xfs_perag	*pag,
+	struct xfs_mount	*mp,
 	struct xfs_trans	*tp,
-	xfs_agblock_t		agbno,
-	xfs_extlen_t		aglen,
-	xfs_agblock_t		*fbno,
-	xfs_extlen_t		*flen,
+	const struct xfs_bmbt_irec *irec,
+	xfs_extlen_t		*shared_offset,
+	xfs_extlen_t		*shared_len,
 	bool			find_end_of_shared)
 {
 	struct xfs_buf		*agbp;
+	struct xfs_perag	*pag;
 	struct xfs_btree_cur	*cur;
 	int			error;
+	xfs_agblock_t		orig_bno, found_bno;
+
+	pag = xfs_perag_get(mp, XFS_FSB_TO_AGNO(mp, irec->br_startblock));
+	orig_bno = XFS_FSB_TO_AGBNO(mp, irec->br_startblock);
 
 	error = xfs_alloc_read_agf(pag, tp, 0, &agbp);
 	if (error)
-		return error;
+		goto out;
 
-	cur = xfs_refcountbt_init_cursor(pag_mount(pag), tp, agbp, pag);
+	cur = xfs_refcountbt_init_cursor(mp, tp, agbp, pag);
+	error = xfs_refcount_find_shared(cur, orig_bno, irec->br_blockcount,
+			&found_bno, shared_len, find_end_of_shared);
+	xfs_btree_del_cursor(cur, error);
+	xfs_trans_brelse(tp, agbp);
 
-	error = xfs_refcount_find_shared(cur, agbno, aglen, fbno, flen,
-			find_end_of_shared);
+	if (!error && *shared_len)
+		*shared_offset = found_bno - orig_bno;
+out:
+	xfs_perag_put(pag);
+	return error;
+}
 
+/*
+ * Given a file mapping for the rt device, find the lowest-numbered run of
+ * shared blocks within that mapping and return it in shared_offset/shared_len.
+ * The offset is relative to the start of irec.
+ *
+ * If find_end_of_shared is true, return the longest contiguous extent of shared
+ * blocks.  If there are no shared extents, shared_offset and shared_len will be
+ * set to 0;
+ */
+static int
+xfs_reflink_find_rtshared(
+	struct xfs_mount	*mp,
+	struct xfs_trans	*tp,
+	const struct xfs_bmbt_irec *irec,
+	xfs_extlen_t		*shared_offset,
+	xfs_extlen_t		*shared_len,
+	bool			find_end_of_shared)
+{
+	struct xfs_rtgroup	*rtg;
+	struct xfs_btree_cur	*cur;
+	xfs_rgblock_t		orig_bno;
+	xfs_agblock_t		found_bno;
+	int			error;
+
+	BUILD_BUG_ON(NULLRGBLOCK != NULLAGBLOCK);
+
+	/*
+	 * Note: this uses the not quite correct xfs_agblock_t type because
+	 * xfs_refcount_find_shared is shared between the RT and data device
+	 * refcount code.
+	 */
+	orig_bno = xfs_rtb_to_rgbno(mp, irec->br_startblock);
+	rtg = xfs_rtgroup_get(mp, xfs_rtb_to_rgno(mp, irec->br_startblock));
+
+	xfs_rtgroup_lock(rtg, XFS_RTGLOCK_REFCOUNT);
+	cur = xfs_rtrefcountbt_init_cursor(tp, rtg);
+	error = xfs_refcount_find_shared(cur, orig_bno, irec->br_blockcount,
+			&found_bno, shared_len, find_end_of_shared);
 	xfs_btree_del_cursor(cur, error);
+	xfs_rtgroup_unlock(rtg, XFS_RTGLOCK_REFCOUNT);
+	xfs_rtgroup_put(rtg);
 
-	xfs_trans_brelse(tp, agbp);
+	if (!error && *shared_len)
+		*shared_offset = found_bno - orig_bno;
 	return error;
 }
 
@@ -172,11 +231,7 @@ xfs_reflink_trim_around_shared(
 	bool			*shared)
 {
 	struct xfs_mount	*mp = ip->i_mount;
-	struct xfs_perag	*pag;
-	xfs_agblock_t		agbno;
-	xfs_extlen_t		aglen;
-	xfs_agblock_t		fbno;
-	xfs_extlen_t		flen;
+	xfs_extlen_t		shared_offset, shared_len;
 	int			error = 0;
 
 	/* Holes, unwritten, and delalloc extents cannot be shared */
@@ -187,41 +242,37 @@ xfs_reflink_trim_around_shared(
 
 	trace_xfs_reflink_trim_around_shared(ip, irec);
 
-	pag = xfs_perag_get(mp, XFS_FSB_TO_AGNO(mp, irec->br_startblock));
-	agbno = XFS_FSB_TO_AGBNO(mp, irec->br_startblock);
-	aglen = irec->br_blockcount;
-
-	error = xfs_reflink_find_shared(pag, NULL, agbno, aglen, &fbno, &flen,
-			true);
-	xfs_perag_put(pag);
+	if (XFS_IS_REALTIME_INODE(ip))
+		error = xfs_reflink_find_rtshared(mp, NULL, irec,
+				&shared_offset, &shared_len, true);
+	else
+		error = xfs_reflink_find_shared(mp, NULL, irec,
+				&shared_offset, &shared_len, true);
 	if (error)
 		return error;
 
-	*shared = false;
-	if (fbno == NULLAGBLOCK) {
+	if (!shared_len) {
 		/* No shared blocks at all. */
-		return 0;
-	}
-
-	if (fbno == agbno) {
+		*shared = false;
+	} else if (!shared_offset) {
 		/*
-		 * The start of this extent is shared.  Truncate the
-		 * mapping at the end of the shared region so that a
-		 * subsequent iteration starts at the start of the
-		 * unshared region.
+		 * The start of this mapping points to shared space.  Truncate
+		 * the mapping at the end of the shared region so that a
+		 * subsequent iteration starts at the start of the unshared
+		 * region.
 		 */
-		irec->br_blockcount = flen;
+		irec->br_blockcount = shared_len;
 		*shared = true;
-		return 0;
+	} else {
+		/*
+		 * There's a shared region that doesn't start at the beginning
+		 * of the mapping.  Truncate the mapping at the start of the
+		 * shared extent so that a subsequent iteration starts at the
+		 * start of the shared region.
+		 */
+		irec->br_blockcount = shared_offset;
+		*shared = false;
 	}
-
-	/*
-	 * There's a shared extent midway through this extent.
-	 * Truncate the mapping at the start of the shared
-	 * extent so that a subsequent iteration starts at the
-	 * start of the shared region.
-	 */
-	irec->br_blockcount = fbno - agbno;
 	return 0;
 }
 
@@ -389,20 +440,26 @@ xfs_reflink_fill_cow_hole(
 	struct xfs_mount	*mp = ip->i_mount;
 	struct xfs_trans	*tp;
 	xfs_filblks_t		resaligned;
-	xfs_extlen_t		resblks;
+	unsigned int		dblocks = 0, rblocks = 0;
 	int			nimaps;
 	int			error;
 	bool			found;
 
 	resaligned = xfs_aligned_fsb_count(imap->br_startoff,
 		imap->br_blockcount, xfs_get_cowextsz_hint(ip));
-	resblks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
+	if (XFS_IS_REALTIME_INODE(ip)) {
+		dblocks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
+		rblocks = resaligned;
+	} else {
+		dblocks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
+		rblocks = 0;
+	}
 
 	xfs_iunlock(ip, *lockmode);
 	*lockmode = 0;
 
-	error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write, resblks, 0,
-			false, &tp);
+	error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write, dblocks,
+			rblocks, false, &tp);
 	if (error)
 		return error;
 
@@ -571,6 +628,7 @@ xfs_reflink_cancel_cow_blocks(
 	struct xfs_ifork		*ifp = xfs_ifork_ptr(ip, XFS_COW_FORK);
 	struct xfs_bmbt_irec		got, del;
 	struct xfs_iext_cursor		icur;
+	bool				isrt = XFS_IS_REALTIME_INODE(ip);
 	int				error = 0;
 
 	if (!xfs_inode_has_cow_data(ip))
@@ -598,12 +656,13 @@ xfs_reflink_cancel_cow_blocks(
 			ASSERT((*tpp)->t_highest_agno == NULLAGNUMBER);
 
 			/* Free the CoW orphan record. */
-			xfs_refcount_free_cow_extent(*tpp, del.br_startblock,
-					del.br_blockcount);
+			xfs_refcount_free_cow_extent(*tpp, isrt,
+					del.br_startblock, del.br_blockcount);
 
 			error = xfs_free_extent_later(*tpp, del.br_startblock,
 					del.br_blockcount, NULL,
-					XFS_AG_RESV_NONE, 0);
+					XFS_AG_RESV_NONE,
+					isrt ? XFS_FREE_EXTENT_REALTIME : 0);
 			if (error)
 				break;
 
@@ -687,6 +746,35 @@ out:
 	return error;
 }
 
+#ifdef CONFIG_XFS_QUOTA
+/*
+ * Update quota accounting for a remapping operation.  When we're remapping
+ * something from the CoW fork to the data fork, we must update the quota
+ * accounting for delayed allocations.  For remapping from the data fork to the
+ * data fork, use regular block accounting.
+ */
+static inline void
+xfs_reflink_update_quota(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*ip,
+	bool			is_cow,
+	int64_t			blocks)
+{
+	unsigned int		qflag;
+
+	if (XFS_IS_REALTIME_INODE(ip)) {
+		qflag = is_cow ? XFS_TRANS_DQ_DELRTBCOUNT :
+				 XFS_TRANS_DQ_RTBCOUNT;
+	} else {
+		qflag = is_cow ? XFS_TRANS_DQ_DELBCOUNT :
+				 XFS_TRANS_DQ_BCOUNT;
+	}
+	xfs_trans_mod_dquot_byino(tp, ip, qflag, blocks);
+}
+#else
+# define xfs_reflink_update_quota(tp, ip, is_cow, blocks)	((void)0)
+#endif
+
 /*
  * Remap part of the CoW fork into the data fork.
  *
@@ -710,6 +798,7 @@ xfs_reflink_end_cow_extent(
 	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, XFS_COW_FORK);
 	unsigned int		resblks;
 	int			nmaps;
+	bool			isrt = XFS_IS_REALTIME_INODE(ip);
 	int			error;
 
 	resblks = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
@@ -779,9 +868,8 @@ xfs_reflink_end_cow_extent(
 		 * or not), unmap the extent and drop its refcount.
 		 */
 		xfs_bmap_unmap_extent(tp, ip, XFS_DATA_FORK, &data);
-		xfs_refcount_decrease_extent(tp, &data);
-		xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT,
-				-data.br_blockcount);
+		xfs_refcount_decrease_extent(tp, isrt, &data);
+		xfs_reflink_update_quota(tp, ip, false, -data.br_blockcount);
 	} else if (data.br_startblock == DELAYSTARTBLOCK) {
 		int		done;
 
@@ -799,14 +887,14 @@ xfs_reflink_end_cow_extent(
 	}
 
 	/* Free the CoW orphan record. */
-	xfs_refcount_free_cow_extent(tp, del.br_startblock, del.br_blockcount);
+	xfs_refcount_free_cow_extent(tp, isrt, del.br_startblock,
+			del.br_blockcount);
 
 	/* Map the new blocks into the data fork. */
 	xfs_bmap_map_extent(tp, ip, XFS_DATA_FORK, &del);
 
 	/* Charge this new data fork mapping to the on-disk quota. */
-	xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_DELBCOUNT,
-			(long)del.br_blockcount);
+	xfs_reflink_update_quota(tp, ip, true, del.br_blockcount);
 
 	/* Remove the mapping from the CoW fork. */
 	xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
@@ -895,20 +983,29 @@ xfs_reflink_recover_cow(
 	struct xfs_mount	*mp)
 {
 	struct xfs_perag	*pag = NULL;
+	struct xfs_rtgroup	*rtg = NULL;
 	int			error = 0;
 
 	if (!xfs_has_reflink(mp))
 		return 0;
 
 	while ((pag = xfs_perag_next(mp, pag))) {
-		error = xfs_refcount_recover_cow_leftovers(mp, pag);
+		error = xfs_refcount_recover_cow_leftovers(pag_group(pag));
 		if (error) {
 			xfs_perag_rele(pag);
-			break;
+			return error;
 		}
 	}
 
-	return error;
+	while ((rtg = xfs_rtgroup_next(mp, rtg))) {
+		error = xfs_refcount_recover_cow_leftovers(rtg_group(rtg));
+		if (error) {
+			xfs_rtgroup_rele(rtg);
+			return error;
+		}
+	}
+
+	return 0;
 }
 
 /*
@@ -1100,14 +1197,28 @@ out_error:
 static int
 xfs_reflink_ag_has_free_space(
 	struct xfs_mount	*mp,
-	xfs_agnumber_t		agno)
+	struct xfs_inode	*ip,
+	xfs_fsblock_t		fsb)
 {
 	struct xfs_perag	*pag;
+	xfs_agnumber_t		agno;
 	int			error = 0;
 
 	if (!xfs_has_rmapbt(mp))
 		return 0;
+	if (XFS_IS_REALTIME_INODE(ip)) {
+		struct xfs_rtgroup	*rtg;
+		xfs_rgnumber_t		rgno;
+
+		rgno = xfs_rtb_to_rgno(mp, fsb);
+		rtg = xfs_rtgroup_get(mp, rgno);
+		if (xfs_metafile_resv_critical(rtg_rmap(rtg)))
+			error = -ENOSPC;
+		xfs_rtgroup_put(rtg);
+		return error;
+	}
 
+	agno = XFS_FSB_TO_AGNO(mp, fsb);
 	pag = xfs_perag_get(mp, agno);
 	if (xfs_ag_resv_critical(pag, XFS_AG_RESV_RMAPBT) ||
 	    xfs_ag_resv_critical(pag, XFS_AG_RESV_METADATA))
@@ -1131,10 +1242,11 @@ xfs_reflink_remap_extent(
 	struct xfs_trans	*tp;
 	xfs_off_t		newlen;
 	int64_t			qdelta = 0;
-	unsigned int		resblks;
+	unsigned int		dblocks, rblocks, resblks;
 	bool			quota_reserved = true;
 	bool			smap_real;
 	bool			dmap_written = xfs_bmap_is_written_extent(dmap);
+	bool			isrt = XFS_IS_REALTIME_INODE(ip);
 	int			iext_delta = 0;
 	int			nimaps;
 	int			error;
@@ -1161,8 +1273,15 @@ xfs_reflink_remap_extent(
 	 * we're remapping.
 	 */
 	resblks = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
+	if (XFS_IS_REALTIME_INODE(ip)) {
+		dblocks = resblks;
+		rblocks = dmap->br_blockcount;
+	} else {
+		dblocks = resblks + dmap->br_blockcount;
+		rblocks = 0;
+	}
 	error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write,
-			resblks + dmap->br_blockcount, 0, false, &tp);
+			dblocks, rblocks, false, &tp);
 	if (error == -EDQUOT || error == -ENOSPC) {
 		quota_reserved = false;
 		error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write,
@@ -1213,8 +1332,8 @@ xfs_reflink_remap_extent(
 
 	/* No reflinking if the AG of the dest mapping is low on space. */
 	if (dmap_written) {
-		error = xfs_reflink_ag_has_free_space(mp,
-				XFS_FSB_TO_AGNO(mp, dmap->br_startblock));
+		error = xfs_reflink_ag_has_free_space(mp, ip,
+				dmap->br_startblock);
 		if (error)
 			goto out_cancel;
 	}
@@ -1242,8 +1361,15 @@ xfs_reflink_remap_extent(
 	 * done.
 	 */
 	if (!quota_reserved && !smap_real && dmap_written) {
-		error = xfs_trans_reserve_quota_nblks(tp, ip,
-				dmap->br_blockcount, 0, false);
+		if (XFS_IS_REALTIME_INODE(ip)) {
+			dblocks = 0;
+			rblocks = dmap->br_blockcount;
+		} else {
+			dblocks = dmap->br_blockcount;
+			rblocks = 0;
+		}
+		error = xfs_trans_reserve_quota_nblks(tp, ip, dblocks, rblocks,
+				false);
 		if (error)
 			goto out_cancel;
 	}
@@ -1264,7 +1390,7 @@ xfs_reflink_remap_extent(
 		 * or not), unmap the extent and drop its refcount.
 		 */
 		xfs_bmap_unmap_extent(tp, ip, XFS_DATA_FORK, &smap);
-		xfs_refcount_decrease_extent(tp, &smap);
+		xfs_refcount_decrease_extent(tp, isrt, &smap);
 		qdelta -= smap.br_blockcount;
 	} else if (smap.br_startblock == DELAYSTARTBLOCK) {
 		int		done;
@@ -1287,12 +1413,12 @@ xfs_reflink_remap_extent(
 	 * its refcount and map it into the file.
 	 */
 	if (dmap_written) {
-		xfs_refcount_increase_extent(tp, dmap);
+		xfs_refcount_increase_extent(tp, isrt, dmap);
 		xfs_bmap_map_extent(tp, ip, XFS_DATA_FORK, dmap);
 		qdelta += dmap->br_blockcount;
 	}
 
-	xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT, qdelta);
+	xfs_reflink_update_quota(tp, ip, false, qdelta);
 
 	/* Update dest isize if needed. */
 	newlen = XFS_FSB_TO_B(mp, dmap->br_startoff + dmap->br_blockcount);
@@ -1466,8 +1592,8 @@ xfs_reflink_remap_prep(
 
 	/* Check file eligibility and prepare for block sharing. */
 	ret = -EINVAL;
-	/* Don't reflink realtime inodes */
-	if (XFS_IS_REALTIME_INODE(src) || XFS_IS_REALTIME_INODE(dest))
+	/* Can't reflink between data and rt volumes */
+	if (XFS_IS_REALTIME_INODE(src) != XFS_IS_REALTIME_INODE(dest))
 		goto out_unlock;
 
 	/* Don't share DAX file data with non-DAX file. */
@@ -1547,27 +1673,23 @@ xfs_reflink_inode_has_shared_extents(
 	*has_shared = false;
 	found = xfs_iext_lookup_extent(ip, ifp, 0, &icur, &got);
 	while (found) {
-		struct xfs_perag	*pag;
-		xfs_agblock_t		agbno;
-		xfs_extlen_t		aglen;
-		xfs_agblock_t		rbno;
-		xfs_extlen_t		rlen;
+		xfs_extlen_t		shared_offset, shared_len;
 
 		if (isnullstartblock(got.br_startblock) ||
 		    got.br_state != XFS_EXT_NORM)
 			goto next;
 
-		pag = xfs_perag_get(mp, XFS_FSB_TO_AGNO(mp, got.br_startblock));
-		agbno = XFS_FSB_TO_AGBNO(mp, got.br_startblock);
-		aglen = got.br_blockcount;
-		error = xfs_reflink_find_shared(pag, tp, agbno, aglen,
-				&rbno, &rlen, false);
-		xfs_perag_put(pag);
+		if (XFS_IS_REALTIME_INODE(ip))
+			error = xfs_reflink_find_rtshared(mp, tp, &got,
+					&shared_offset, &shared_len, false);
+		else
+			error = xfs_reflink_find_shared(mp, tp, &got,
+					&shared_offset, &shared_len, false);
 		if (error)
 			return error;
 
 		/* Is there still a shared block here? */
-		if (rbno != NULLAGBLOCK) {
+		if (shared_len) {
 			*has_shared = true;
 			return 0;
 		}
@@ -1700,3 +1822,28 @@ out:
 	trace_xfs_reflink_unshare_error(ip, error, _RET_IP_);
 	return error;
 }
+
+/*
+ * Can we use reflink with this realtime extent size?  Note that we don't check
+ * for rblocks > 0 here because this can be called as part of attaching a new
+ * rt section.
+ */
+bool
+xfs_reflink_supports_rextsize(
+	struct xfs_mount	*mp,
+	unsigned int		rextsize)
+{
+	/* reflink on the realtime device requires rtgroups */
+	if (!xfs_has_rtgroups(mp))
+	       return false;
+
+	/*
+	 * Reflink doesn't support rt extent size larger than a single fsblock
+	 * because we would have to perform CoW-around for unaligned write
+	 * requests to guarantee that we always remap entire rt extents.
+	 */
+	if (rextsize != 1)
+		return false;
+
+	return true;
+}
diff --git a/fs/xfs/xfs_reflink.h b/fs/xfs/xfs_reflink.h
index 4a58e4533671..cc4e92278279 100644
--- a/fs/xfs/xfs_reflink.h
+++ b/fs/xfs/xfs_reflink.h
@@ -25,7 +25,7 @@ xfs_can_free_cowblocks(struct xfs_inode *ip)
 	return true;
 }
 
-extern int xfs_reflink_trim_around_shared(struct xfs_inode *ip,
+int xfs_reflink_trim_around_shared(struct xfs_inode *ip,
 		struct xfs_bmbt_irec *irec, bool *shared);
 int xfs_bmap_trim_cow(struct xfs_inode *ip, struct xfs_bmbt_irec *imap,
 		bool *shared);
@@ -62,4 +62,6 @@ extern int xfs_reflink_remap_blocks(struct xfs_inode *src, loff_t pos_in,
 extern int xfs_reflink_update_dest(struct xfs_inode *dest, xfs_off_t newlen,
 		xfs_extlen_t cowextsize, unsigned int remap_flags);
 
+bool xfs_reflink_supports_rextsize(struct xfs_mount *mp, unsigned int rextsize);
+
 #endif /* __XFS_REFLINK_H */
diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c
index a69967f9d88e..d8e6d073d64d 100644
--- a/fs/xfs/xfs_rtalloc.c
+++ b/fs/xfs/xfs_rtalloc.c
@@ -31,6 +31,8 @@
 #include "xfs_rtgroup.h"
 #include "xfs_error.h"
 #include "xfs_trace.h"
+#include "xfs_rtrefcount_btree.h"
+#include "xfs_reflink.h"
 
 /*
  * Return whether there are any free extents in the size range given
@@ -593,7 +595,7 @@ xfs_rtalloc_sumlevel(
  * specified.  If we don't get maxlen then use prod to trim
  * the length, if given.  The lengths are all in rtextents.
  */
-STATIC int
+static int
 xfs_rtallocate_extent_size(
 	struct xfs_rtalloc_args	*args,
 	xfs_rtxlen_t		minlen,	/* minimum length to allocate */
@@ -994,6 +996,7 @@ xfs_growfs_rt_bmblock(
 	 */
 	mp->m_features |= XFS_FEAT_REALTIME;
 	xfs_rtrmapbt_compute_maxlevels(mp);
+	xfs_rtrefcountbt_compute_maxlevels(mp);
 
 	kfree(nmp);
 	return 0;
@@ -1177,6 +1180,7 @@ xfs_growfs_check_rtgeom(
 	nmp->m_sb.sb_dblocks = dblocks;
 
 	xfs_rtrmapbt_compute_maxlevels(nmp);
+	xfs_rtrefcountbt_compute_maxlevels(nmp);
 	xfs_trans_resv_calc(nmp, M_RES(nmp));
 
 	/*
@@ -1289,8 +1293,10 @@ xfs_growfs_rt(
 			goto out_unlock;
 		if (xfs_has_quota(mp))
 			goto out_unlock;
-	}
-	if (xfs_has_reflink(mp))
+		if (xfs_has_reflink(mp))
+			goto out_unlock;
+	} else if (xfs_has_reflink(mp) &&
+		   !xfs_reflink_supports_rextsize(mp, in->extsize))
 		goto out_unlock;
 
 	error = xfs_sb_validate_fsb_count(&mp->m_sb, in->newblocks);
@@ -1547,6 +1553,11 @@ xfs_rt_resv_init(
 		err2 = xfs_metafile_resv_init(rtg_rmap(rtg), ask);
 		if (err2 && !error)
 			error = err2;
+
+		ask = xfs_rtrefcountbt_calc_reserves(mp);
+		err2 = xfs_metafile_resv_init(rtg_refcount(rtg), ask);
+		if (err2 && !error)
+			error = err2;
 	}
 
 	return error;
@@ -1950,7 +1961,7 @@ out_unlock:
 	goto out_release;
 }
 
-static int
+int
 xfs_rtallocate_rtgs(
 	struct xfs_trans	*tp,
 	xfs_fsblock_t		bno_hint,
@@ -2015,7 +2026,10 @@ xfs_rtallocate_align(
 	if (*noalign) {
 		align = mp->m_sb.sb_rextsize;
 	} else {
-		align = xfs_get_extsz_hint(ap->ip);
+		if (ap->flags & XFS_BMAPI_COWFORK)
+			align = xfs_get_cowextsz_hint(ap->ip);
+		else
+			align = xfs_get_extsz_hint(ap->ip);
 		if (!align)
 			align = 1;
 		if (align == mp->m_sb.sb_rextsize)
diff --git a/fs/xfs/xfs_rtalloc.h b/fs/xfs/xfs_rtalloc.h
index 9044f7226ab6..0d95b29092c9 100644
--- a/fs/xfs/xfs_rtalloc.h
+++ b/fs/xfs/xfs_rtalloc.h
@@ -77,4 +77,9 @@ xfs_growfs_check_rtgeom(const struct xfs_mount *mp,
 }
 #endif	/* CONFIG_XFS_RT */
 
+int xfs_rtallocate_rtgs(struct xfs_trans *tp, xfs_fsblock_t bno_hint,
+		xfs_rtxlen_t minlen, xfs_rtxlen_t maxlen, xfs_rtxlen_t prod,
+		bool wasdel, bool initial_user_data, xfs_rtblock_t *bno,
+		xfs_extlen_t *blen);
+
 #endif	/* __XFS_RTALLOC_H__ */
diff --git a/fs/xfs/xfs_stats.c b/fs/xfs/xfs_stats.c
index b7f2988bc03b..35c7fb3ba324 100644
--- a/fs/xfs/xfs_stats.c
+++ b/fs/xfs/xfs_stats.c
@@ -54,7 +54,8 @@ int xfs_stats_format(struct xfsstats __percpu *stats, char *buf)
 		{ "rmapbt_mem",		xfsstats_offset(xs_rcbag_2)	},
 		{ "rcbagbt",		xfsstats_offset(xs_rtrmap_2)	},
 		{ "rtrmapbt",		xfsstats_offset(xs_rtrmap_mem_2)},
-		{ "rtrmapbt_mem",	xfsstats_offset(xs_qm_dqreclaims)},
+		{ "rtrmapbt_mem",	xfsstats_offset(xs_rtrefcbt_2)	},
+		{ "rtrefcntbt",		xfsstats_offset(xs_qm_dqreclaims)},
 		/* we print both series of quota information together */
 		{ "qm",			xfsstats_offset(xs_xstrat_bytes)},
 	};
diff --git a/fs/xfs/xfs_stats.h b/fs/xfs/xfs_stats.h
index 9c47de5dff2d..15ba1abcf253 100644
--- a/fs/xfs/xfs_stats.h
+++ b/fs/xfs/xfs_stats.h
@@ -129,6 +129,7 @@ struct __xfsstats {
 	uint32_t		xs_rcbag_2[__XBTS_MAX];
 	uint32_t		xs_rtrmap_2[__XBTS_MAX];
 	uint32_t		xs_rtrmap_mem_2[__XBTS_MAX];
+	uint32_t		xs_rtrefcbt_2[__XBTS_MAX];
 	uint32_t		xs_qm_dqreclaims;
 	uint32_t		xs_qm_dqreclaim_misses;
 	uint32_t		xs_qm_dquot_dups;
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index ecd5a9f444d8..7c3f996cd39e 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1754,9 +1754,11 @@ xfs_fs_fill_super(
 		xfs_warn_experimental(mp, XFS_EXPERIMENTAL_METADIR);
 
 	if (xfs_has_reflink(mp)) {
-		if (mp->m_sb.sb_rblocks) {
+		if (xfs_has_realtime(mp) &&
+		    !xfs_reflink_supports_rextsize(mp, mp->m_sb.sb_rextsize)) {
 			xfs_alert(mp,
-	"reflink not compatible with realtime device!");
+	"reflink not compatible with realtime extent size %u!",
+					mp->m_sb.sb_rextsize);
 			error = -EINVAL;
 			goto out_filestream_unmount;
 		}
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 84cdc145e2d9..4fe689410eb6 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -3305,56 +3305,62 @@ TRACE_EVENT(xfs_ag_resv_init_error,
 /* refcount tracepoint classes */
 
 DECLARE_EVENT_CLASS(xfs_refcount_class,
-	TP_PROTO(struct xfs_btree_cur *cur, xfs_agblock_t agbno,
+	TP_PROTO(struct xfs_btree_cur *cur, xfs_agblock_t gbno,
 		xfs_extlen_t len),
-	TP_ARGS(cur, agbno, len),
+	TP_ARGS(cur, gbno, len),
 	TP_STRUCT__entry(
 		__field(dev_t, dev)
+		__field(enum xfs_group_type, type)
 		__field(xfs_agnumber_t, agno)
-		__field(xfs_agblock_t, agbno)
+		__field(xfs_agblock_t, gbno)
 		__field(xfs_extlen_t, len)
 	),
 	TP_fast_assign(
 		__entry->dev = cur->bc_mp->m_super->s_dev;
+		__entry->type = cur->bc_group->xg_type;
 		__entry->agno = cur->bc_group->xg_gno;
-		__entry->agbno = agbno;
+		__entry->gbno = gbno;
 		__entry->len = len;
 	),
-	TP_printk("dev %d:%d agno 0x%x agbno 0x%x fsbcount 0x%x",
+	TP_printk("dev %d:%d %sno 0x%x gbno 0x%x fsbcount 0x%x",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __print_symbolic(__entry->type, XG_TYPE_STRINGS),
 		  __entry->agno,
-		  __entry->agbno,
+		  __entry->gbno,
 		  __entry->len)
 );
 #define DEFINE_REFCOUNT_EVENT(name) \
 DEFINE_EVENT(xfs_refcount_class, name, \
-	TP_PROTO(struct xfs_btree_cur *cur, xfs_agblock_t agbno, \
+	TP_PROTO(struct xfs_btree_cur *cur, xfs_agblock_t gbno, \
 		xfs_extlen_t len), \
-	TP_ARGS(cur, agbno, len))
+	TP_ARGS(cur, gbno, len))
 
 TRACE_DEFINE_ENUM(XFS_LOOKUP_EQi);
 TRACE_DEFINE_ENUM(XFS_LOOKUP_LEi);
 TRACE_DEFINE_ENUM(XFS_LOOKUP_GEi);
 TRACE_EVENT(xfs_refcount_lookup,
-	TP_PROTO(struct xfs_btree_cur *cur, xfs_agblock_t agbno,
+	TP_PROTO(struct xfs_btree_cur *cur, xfs_agblock_t gbno,
 		xfs_lookup_t dir),
-	TP_ARGS(cur, agbno, dir),
+	TP_ARGS(cur, gbno, dir),
 	TP_STRUCT__entry(
 		__field(dev_t, dev)
+		__field(enum xfs_group_type, type)
 		__field(xfs_agnumber_t, agno)
-		__field(xfs_agblock_t, agbno)
+		__field(xfs_agblock_t, gbno)
 		__field(xfs_lookup_t, dir)
 	),
 	TP_fast_assign(
 		__entry->dev = cur->bc_mp->m_super->s_dev;
+		__entry->type = cur->bc_group->xg_type;
 		__entry->agno = cur->bc_group->xg_gno;
-		__entry->agbno = agbno;
+		__entry->gbno = gbno;
 		__entry->dir = dir;
 	),
-	TP_printk("dev %d:%d agno 0x%x agbno 0x%x cmp %s(%d)",
+	TP_printk("dev %d:%d %sno 0x%x gbno 0x%x cmp %s(%d)",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __print_symbolic(__entry->type, XG_TYPE_STRINGS),
 		  __entry->agno,
-		  __entry->agbno,
+		  __entry->gbno,
 		  __print_symbolic(__entry->dir, XFS_AG_BTREE_CMP_FORMAT_STR),
 		  __entry->dir)
 )
@@ -3365,6 +3371,7 @@ DECLARE_EVENT_CLASS(xfs_refcount_extent_class,
 	TP_ARGS(cur, irec),
 	TP_STRUCT__entry(
 		__field(dev_t, dev)
+		__field(enum xfs_group_type, type)
 		__field(xfs_agnumber_t, agno)
 		__field(enum xfs_refc_domain, domain)
 		__field(xfs_agblock_t, startblock)
@@ -3373,14 +3380,16 @@ DECLARE_EVENT_CLASS(xfs_refcount_extent_class,
 	),
 	TP_fast_assign(
 		__entry->dev = cur->bc_mp->m_super->s_dev;
+		__entry->type = cur->bc_group->xg_type;
 		__entry->agno = cur->bc_group->xg_gno;
 		__entry->domain = irec->rc_domain;
 		__entry->startblock = irec->rc_startblock;
 		__entry->blockcount = irec->rc_blockcount;
 		__entry->refcount = irec->rc_refcount;
 	),
-	TP_printk("dev %d:%d agno 0x%x dom %s agbno 0x%x fsbcount 0x%x refcount %u",
+	TP_printk("dev %d:%d %sno 0x%x dom %s gbno 0x%x fsbcount 0x%x refcount %u",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __print_symbolic(__entry->type, XG_TYPE_STRINGS),
 		  __entry->agno,
 		  __print_symbolic(__entry->domain, XFS_REFC_DOMAIN_STRINGS),
 		  __entry->startblock,
@@ -3396,49 +3405,53 @@ DEFINE_EVENT(xfs_refcount_extent_class, name, \
 /* single-rcext and an agbno tracepoint class */
 DECLARE_EVENT_CLASS(xfs_refcount_extent_at_class,
 	TP_PROTO(struct xfs_btree_cur *cur, struct xfs_refcount_irec *irec,
-		 xfs_agblock_t agbno),
-	TP_ARGS(cur, irec, agbno),
+		 xfs_agblock_t gbno),
+	TP_ARGS(cur, irec, gbno),
 	TP_STRUCT__entry(
 		__field(dev_t, dev)
+		__field(enum xfs_group_type, type)
 		__field(xfs_agnumber_t, agno)
 		__field(enum xfs_refc_domain, domain)
 		__field(xfs_agblock_t, startblock)
 		__field(xfs_extlen_t, blockcount)
 		__field(xfs_nlink_t, refcount)
-		__field(xfs_agblock_t, agbno)
+		__field(xfs_agblock_t, gbno)
 	),
 	TP_fast_assign(
 		__entry->dev = cur->bc_mp->m_super->s_dev;
+		__entry->type = cur->bc_group->xg_type;
 		__entry->agno = cur->bc_group->xg_gno;
 		__entry->domain = irec->rc_domain;
 		__entry->startblock = irec->rc_startblock;
 		__entry->blockcount = irec->rc_blockcount;
 		__entry->refcount = irec->rc_refcount;
-		__entry->agbno = agbno;
+		__entry->gbno = gbno;
 	),
-	TP_printk("dev %d:%d agno 0x%x dom %s agbno 0x%x fsbcount 0x%x refcount %u @ agbno 0x%x",
+	TP_printk("dev %d:%d %sno 0x%x dom %s gbno 0x%x fsbcount 0x%x refcount %u @ gbno 0x%x",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __print_symbolic(__entry->type, XG_TYPE_STRINGS),
 		  __entry->agno,
 		  __print_symbolic(__entry->domain, XFS_REFC_DOMAIN_STRINGS),
 		  __entry->startblock,
 		  __entry->blockcount,
 		  __entry->refcount,
-		  __entry->agbno)
+		  __entry->gbno)
 )
 
 #define DEFINE_REFCOUNT_EXTENT_AT_EVENT(name) \
 DEFINE_EVENT(xfs_refcount_extent_at_class, name, \
 	TP_PROTO(struct xfs_btree_cur *cur, struct xfs_refcount_irec *irec, \
-		 xfs_agblock_t agbno), \
-	TP_ARGS(cur, irec, agbno))
+		 xfs_agblock_t gbno), \
+	TP_ARGS(cur, irec, gbno))
 
 /* double-rcext tracepoint class */
 DECLARE_EVENT_CLASS(xfs_refcount_double_extent_class,
 	TP_PROTO(struct xfs_btree_cur *cur, struct xfs_refcount_irec *i1,
-		struct xfs_refcount_irec *i2),
+		 struct xfs_refcount_irec *i2),
 	TP_ARGS(cur, i1, i2),
 	TP_STRUCT__entry(
 		__field(dev_t, dev)
+		__field(enum xfs_group_type, type)
 		__field(xfs_agnumber_t, agno)
 		__field(enum xfs_refc_domain, i1_domain)
 		__field(xfs_agblock_t, i1_startblock)
@@ -3451,6 +3464,7 @@ DECLARE_EVENT_CLASS(xfs_refcount_double_extent_class,
 	),
 	TP_fast_assign(
 		__entry->dev = cur->bc_mp->m_super->s_dev;
+		__entry->type = cur->bc_group->xg_type;
 		__entry->agno = cur->bc_group->xg_gno;
 		__entry->i1_domain = i1->rc_domain;
 		__entry->i1_startblock = i1->rc_startblock;
@@ -3461,9 +3475,10 @@ DECLARE_EVENT_CLASS(xfs_refcount_double_extent_class,
 		__entry->i2_blockcount = i2->rc_blockcount;
 		__entry->i2_refcount = i2->rc_refcount;
 	),
-	TP_printk("dev %d:%d agno 0x%x dom %s agbno 0x%x fsbcount 0x%x refcount %u -- "
-		  "dom %s agbno 0x%x fsbcount 0x%x refcount %u",
+	TP_printk("dev %d:%d %sno 0x%x dom %s gbno 0x%x fsbcount 0x%x refcount %u -- "
+		  "dom %s gbno 0x%x fsbcount 0x%x refcount %u",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __print_symbolic(__entry->type, XG_TYPE_STRINGS),
 		  __entry->agno,
 		  __print_symbolic(__entry->i1_domain, XFS_REFC_DOMAIN_STRINGS),
 		  __entry->i1_startblock,
@@ -3484,10 +3499,11 @@ DEFINE_EVENT(xfs_refcount_double_extent_class, name, \
 /* double-rcext and an agbno tracepoint class */
 DECLARE_EVENT_CLASS(xfs_refcount_double_extent_at_class,
 	TP_PROTO(struct xfs_btree_cur *cur, struct xfs_refcount_irec *i1,
-		 struct xfs_refcount_irec *i2, xfs_agblock_t agbno),
-	TP_ARGS(cur, i1, i2, agbno),
+		 struct xfs_refcount_irec *i2, xfs_agblock_t gbno),
+	TP_ARGS(cur, i1, i2, gbno),
 	TP_STRUCT__entry(
 		__field(dev_t, dev)
+		__field(enum xfs_group_type, type)
 		__field(xfs_agnumber_t, agno)
 		__field(enum xfs_refc_domain, i1_domain)
 		__field(xfs_agblock_t, i1_startblock)
@@ -3497,10 +3513,11 @@ DECLARE_EVENT_CLASS(xfs_refcount_double_extent_at_class,
 		__field(xfs_agblock_t, i2_startblock)
 		__field(xfs_extlen_t, i2_blockcount)
 		__field(xfs_nlink_t, i2_refcount)
-		__field(xfs_agblock_t, agbno)
+		__field(xfs_agblock_t, gbno)
 	),
 	TP_fast_assign(
 		__entry->dev = cur->bc_mp->m_super->s_dev;
+		__entry->type = cur->bc_group->xg_type;
 		__entry->agno = cur->bc_group->xg_gno;
 		__entry->i1_domain = i1->rc_domain;
 		__entry->i1_startblock = i1->rc_startblock;
@@ -3510,11 +3527,12 @@ DECLARE_EVENT_CLASS(xfs_refcount_double_extent_at_class,
 		__entry->i2_startblock = i2->rc_startblock;
 		__entry->i2_blockcount = i2->rc_blockcount;
 		__entry->i2_refcount = i2->rc_refcount;
-		__entry->agbno = agbno;
+		__entry->gbno = gbno;
 	),
-	TP_printk("dev %d:%d agno 0x%x dom %s agbno 0x%x fsbcount 0x%x refcount %u -- "
-		  "dom %s agbno 0x%x fsbcount 0x%x refcount %u @ agbno 0x%x",
+	TP_printk("dev %d:%d %sno 0x%x dom %s gbno 0x%x fsbcount 0x%x refcount %u -- "
+		  "dom %s gbno 0x%x fsbcount 0x%x refcount %u @ gbno 0x%x",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __print_symbolic(__entry->type, XG_TYPE_STRINGS),
 		  __entry->agno,
 		  __print_symbolic(__entry->i1_domain, XFS_REFC_DOMAIN_STRINGS),
 		  __entry->i1_startblock,
@@ -3524,14 +3542,14 @@ DECLARE_EVENT_CLASS(xfs_refcount_double_extent_at_class,
 		  __entry->i2_startblock,
 		  __entry->i2_blockcount,
 		  __entry->i2_refcount,
-		  __entry->agbno)
+		  __entry->gbno)
 )
 
 #define DEFINE_REFCOUNT_DOUBLE_EXTENT_AT_EVENT(name) \
 DEFINE_EVENT(xfs_refcount_double_extent_at_class, name, \
 	TP_PROTO(struct xfs_btree_cur *cur, struct xfs_refcount_irec *i1, \
-		struct xfs_refcount_irec *i2, xfs_agblock_t agbno), \
-	TP_ARGS(cur, i1, i2, agbno))
+		struct xfs_refcount_irec *i2, xfs_agblock_t gbno), \
+	TP_ARGS(cur, i1, i2, gbno))
 
 /* triple-rcext tracepoint class */
 DECLARE_EVENT_CLASS(xfs_refcount_triple_extent_class,
@@ -3540,6 +3558,7 @@ DECLARE_EVENT_CLASS(xfs_refcount_triple_extent_class,
 	TP_ARGS(cur, i1, i2, i3),
 	TP_STRUCT__entry(
 		__field(dev_t, dev)
+		__field(enum xfs_group_type, type)
 		__field(xfs_agnumber_t, agno)
 		__field(enum xfs_refc_domain, i1_domain)
 		__field(xfs_agblock_t, i1_startblock)
@@ -3556,6 +3575,7 @@ DECLARE_EVENT_CLASS(xfs_refcount_triple_extent_class,
 	),
 	TP_fast_assign(
 		__entry->dev = cur->bc_mp->m_super->s_dev;
+		__entry->type = cur->bc_group->xg_type;
 		__entry->agno = cur->bc_group->xg_gno;
 		__entry->i1_domain = i1->rc_domain;
 		__entry->i1_startblock = i1->rc_startblock;
@@ -3570,10 +3590,11 @@ DECLARE_EVENT_CLASS(xfs_refcount_triple_extent_class,
 		__entry->i3_blockcount = i3->rc_blockcount;
 		__entry->i3_refcount = i3->rc_refcount;
 	),
-	TP_printk("dev %d:%d agno 0x%x dom %s agbno 0x%x fsbcount 0x%x refcount %u -- "
-		  "dom %s agbno 0x%x fsbcount 0x%x refcount %u -- "
-		  "dom %s agbno 0x%x fsbcount 0x%x refcount %u",
+	TP_printk("dev %d:%d %sno 0x%x dom %s gbno 0x%x fsbcount 0x%x refcount %u -- "
+		  "dom %s gbno 0x%x fsbcount 0x%x refcount %u -- "
+		  "dom %s gbno 0x%x fsbcount 0x%x refcount %u",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __print_symbolic(__entry->type, XG_TYPE_STRINGS),
 		  __entry->agno,
 		  __print_symbolic(__entry->i1_domain, XFS_REFC_DOMAIN_STRINGS),
 		  __entry->i1_startblock,
@@ -3641,23 +3662,27 @@ DECLARE_EVENT_CLASS(xfs_refcount_deferred_class,
 	TP_ARGS(mp, refc),
 	TP_STRUCT__entry(
 		__field(dev_t, dev)
+		__field(enum xfs_group_type, type)
 		__field(xfs_agnumber_t, agno)
 		__field(int, op)
-		__field(xfs_agblock_t, agbno)
+		__field(xfs_agblock_t, gbno)
 		__field(xfs_extlen_t, len)
 	),
 	TP_fast_assign(
 		__entry->dev = mp->m_super->s_dev;
-		__entry->agno = XFS_FSB_TO_AGNO(mp, refc->ri_startblock);
+		__entry->type = refc->ri_group->xg_type;
+		__entry->agno = refc->ri_group->xg_gno;
 		__entry->op = refc->ri_type;
-		__entry->agbno = XFS_FSB_TO_AGBNO(mp, refc->ri_startblock);
+		__entry->gbno = xfs_fsb_to_gbno(mp, refc->ri_startblock,
+						   refc->ri_group->xg_type);
 		__entry->len = refc->ri_blockcount;
 	),
-	TP_printk("dev %d:%d op %s agno 0x%x agbno 0x%x fsbcount 0x%x",
+	TP_printk("dev %d:%d op %s %sno 0x%x gbno 0x%x fsbcount 0x%x",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
 		  __print_symbolic(__entry->op, XFS_REFCOUNT_INTENT_STRINGS),
+		  __print_symbolic(__entry->type, XG_TYPE_STRINGS),
 		  __entry->agno,
-		  __entry->agbno,
+		  __entry->gbno,
 		  __entry->len)
 );
 #define DEFINE_REFCOUNT_DEFERRED_EVENT(name) \