diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
index 41ea4283c43cb4..f32c9fda5a195f 100644
--- a/fs/xfs/libxfs/xfs_format.h
+++ b/fs/xfs/libxfs/xfs_format.h
@@ -857,6 +857,7 @@ enum xfs_metafile_type {
 	XFS_METAFILE_PRJQUOTA,		/* project quota */
 	XFS_METAFILE_RTBITMAP,		/* rt bitmap */
 	XFS_METAFILE_RTSUMMARY,		/* rt summary */
+	XFS_METAFILE_RTRMAP,		/* rt rmap */
 
 	XFS_METAFILE_MAX
 } __packed;
@@ -868,7 +869,8 @@ enum xfs_metafile_type {
 	{ XFS_METAFILE_GRPQUOTA,	"grpquota" }, \
 	{ XFS_METAFILE_PRJQUOTA,	"prjquota" }, \
 	{ XFS_METAFILE_RTBITMAP,	"rtbitmap" }, \
-	{ XFS_METAFILE_RTSUMMARY,	"rtsummary" }
+	{ XFS_METAFILE_RTSUMMARY,	"rtsummary" }, \
+	{ XFS_METAFILE_RTRMAP,		"rtrmap" }
 
 /*
  * On-disk inode structure.
diff --git a/fs/xfs/libxfs/xfs_inode_buf.c b/fs/xfs/libxfs/xfs_inode_buf.c
index 1648d72d6ed95a..17cb91b89fcaa1 100644
--- a/fs/xfs/libxfs/xfs_inode_buf.c
+++ b/fs/xfs/libxfs/xfs_inode_buf.c
@@ -447,6 +447,15 @@ xfs_dinode_verify_fork(
 		if (!(dip->di_flags2 & cpu_to_be64(XFS_DIFLAG2_METADATA)))
 			return __this_address;
 		switch (be16_to_cpu(dip->di_metatype)) {
+		case XFS_METAFILE_RTRMAP:
+			/*
+			 * growfs must create the rtrmap inodes before adding a
+			 * realtime volume to the filesystem, so we cannot use
+			 * the rtrmapbt predicate here.
+			 */
+			if (!xfs_has_rmapbt(mp))
+				return __this_address;
+			break;
 		default:
 			return __this_address;
 		}
diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
index 1a782339396dc3..7c2b071a58384d 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.c
+++ b/fs/xfs/libxfs/xfs_inode_fork.c
@@ -269,6 +269,9 @@ xfs_iformat_data_fork(
 			return xfs_iformat_btree(ip, dip, XFS_DATA_FORK);
 		case XFS_DINODE_FMT_META_BTREE:
 			switch (ip->i_metatype) {
+			case XFS_METAFILE_RTRMAP:
+				ASSERT(0); /* to be implemented later */
+				return -EFSCORRUPTED;
 			default:
 				break;
 			}
@@ -614,6 +617,9 @@ xfs_iflush_fork(
 			break;
 
 		switch (ip->i_metatype) {
+		case XFS_METAFILE_RTRMAP:
+			ASSERT(0); /* to be implemented later */
+			break;
 		default:
 			ASSERT(0);
 			break;
diff --git a/fs/xfs/libxfs/xfs_rtgroup.c b/fs/xfs/libxfs/xfs_rtgroup.c
index 9e5fdc0dc55cef..1b56c13b282788 100644
--- a/fs/xfs/libxfs/xfs_rtgroup.c
+++ b/fs/xfs/libxfs/xfs_rtgroup.c
@@ -315,6 +315,8 @@ struct xfs_rtginode_ops {
 
 	unsigned int		sick;	/* rtgroup sickness flag */
 
+	unsigned int		fmt_mask; /* all valid data fork formats */
+
 	/* Does the fs have this feature? */
 	bool			(*enabled)(struct xfs_mount *mp);
 
@@ -330,14 +332,29 @@ static const struct xfs_rtginode_ops xfs_rtginode_ops[XFS_RTGI_MAX] = {
 		.name		= "bitmap",
 		.metafile_type	= XFS_METAFILE_RTBITMAP,
 		.sick		= XFS_SICK_RG_BITMAP,
+		.fmt_mask	= (1U << XFS_DINODE_FMT_EXTENTS) |
+				  (1U << XFS_DINODE_FMT_BTREE),
 		.create		= xfs_rtbitmap_create,
 	},
 	[XFS_RTGI_SUMMARY] = {
 		.name		= "summary",
 		.metafile_type	= XFS_METAFILE_RTSUMMARY,
 		.sick		= XFS_SICK_RG_SUMMARY,
+		.fmt_mask	= (1U << XFS_DINODE_FMT_EXTENTS) |
+				  (1U << XFS_DINODE_FMT_BTREE),
 		.create		= xfs_rtsummary_create,
 	},
+	[XFS_RTGI_RMAP] = {
+		.name		= "rmap",
+		.metafile_type	= XFS_METAFILE_RTRMAP,
+		.fmt_mask	= 1U << XFS_DINODE_FMT_META_BTREE,
+		/*
+		 * growfs must create the rtrmap inodes before adding a
+		 * realtime volume to the filesystem, so we cannot use the
+		 * rtrmapbt predicate here.
+		 */
+		.enabled	= xfs_has_rmapbt,
+	},
 };
 
 /* Return the shortname of this rtgroup inode. */
@@ -434,8 +451,7 @@ xfs_rtginode_load(
 		return error;
 	}
 
-	if (XFS_IS_CORRUPT(mp, ip->i_df.if_format != XFS_DINODE_FMT_EXTENTS &&
-			       ip->i_df.if_format != XFS_DINODE_FMT_BTREE)) {
+	if (XFS_IS_CORRUPT(mp, !((1U << ip->i_df.if_format) & ops->fmt_mask))) {
 		xfs_irele(ip);
 		xfs_rtginode_mark_sick(rtg, type);
 		return -EFSCORRUPTED;
diff --git a/fs/xfs/libxfs/xfs_rtgroup.h b/fs/xfs/libxfs/xfs_rtgroup.h
index dc3ce660a01307..5b61291d26691f 100644
--- a/fs/xfs/libxfs/xfs_rtgroup.h
+++ b/fs/xfs/libxfs/xfs_rtgroup.h
@@ -14,6 +14,7 @@ struct xfs_trans;
 enum xfs_rtg_inodes {
 	XFS_RTGI_BITMAP,	/* allocation bitmap */
 	XFS_RTGI_SUMMARY,	/* allocation summary */
+	XFS_RTGI_RMAP,		/* rmap btree inode */
 
 	XFS_RTGI_MAX,
 };
@@ -74,6 +75,11 @@ static inline struct xfs_inode *rtg_summary(const struct xfs_rtgroup *rtg)
 	return rtg->rtg_inodes[XFS_RTGI_SUMMARY];
 }
 
+static inline struct xfs_inode *rtg_rmap(const struct xfs_rtgroup *rtg)
+{
+	return rtg->rtg_inodes[XFS_RTGI_RMAP];
+}
+
 /* Passive rtgroup references */
 static inline struct xfs_rtgroup *
 xfs_rtgroup_get(
@@ -284,6 +290,8 @@ int xfs_rtginode_create(struct xfs_rtgroup *rtg, enum xfs_rtg_inodes type,
 		bool init);
 void xfs_rtginode_irele(struct xfs_inode **ipp);
 
+void xfs_rtginode_irele(struct xfs_inode **ipp);
+
 static inline const char *xfs_rtginode_path(xfs_rgnumber_t rgno,
 		enum xfs_rtg_inodes type)
 {
diff --git a/fs/xfs/libxfs/xfs_rtrmap_btree.c b/fs/xfs/libxfs/xfs_rtrmap_btree.c
index 99d828bb5fe7c3..22aabf326b2ccd 100644
--- a/fs/xfs/libxfs/xfs_rtrmap_btree.c
+++ b/fs/xfs/libxfs/xfs_rtrmap_btree.c
@@ -18,6 +18,7 @@
 #include "xfs_alloc.h"
 #include "xfs_btree.h"
 #include "xfs_btree_staging.h"
+#include "xfs_metafile.h"
 #include "xfs_rmap.h"
 #include "xfs_rtrmap_btree.h"
 #include "xfs_trace.h"
@@ -405,12 +406,10 @@ xfs_rtrmapbt_init_cursor(
 	struct xfs_trans	*tp,
 	struct xfs_rtgroup	*rtg)
 {
-	struct xfs_inode	*ip = NULL;
+	struct xfs_inode	*ip = rtg_rmap(rtg);
 	struct xfs_mount	*mp = rtg_mount(rtg);
 	struct xfs_btree_cur	*cur;
 
-	return NULL; /* XXX */
-
 	xfs_assert_ilocked(ip, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL);
 
 	cur = xfs_btree_alloc_cursor(mp, tp, &xfs_rtrmapbt_ops,
@@ -439,6 +438,7 @@ xfs_rtrmapbt_commit_staged_btree(
 	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
