diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
index a903bd3..9e6aabf 100644
--- a/fs/xfs/Makefile
+++ b/fs/xfs/Makefile
@@ -55,6 +55,7 @@ xfs-y				+= $(addprefix libxfs/, \
 				   xfs_ag_resv.o \
 				   xfs_rmap.o \
 				   xfs_rmap_btree.o \
+				   xfs_rtrmap_btree.o \
 				   xfs_refcount.o \
 				   xfs_refcount_btree.o \
 				   xfs_sb.o \
diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
index d5beaf7..9f2b457 100644
--- a/fs/xfs/libxfs/xfs_btree.c
+++ b/fs/xfs/libxfs/xfs_btree.c
@@ -1220,6 +1220,7 @@ xfs_btree_set_refs(
 		xfs_buf_set_ref(bp, XFS_BMAP_BTREE_REF);
 		break;
 	case XFS_BTNUM_RMAP:
+	case XFS_BTNUM_RTRMAP:
 		xfs_buf_set_ref(bp, XFS_RMAP_BTREE_REF);
 		break;
 	case XFS_BTNUM_REFC:
diff --git a/fs/xfs/libxfs/xfs_btree.h b/fs/xfs/libxfs/xfs_btree.h
index 8913ffa..a9936ac 100644
--- a/fs/xfs/libxfs/xfs_btree.h
+++ b/fs/xfs/libxfs/xfs_btree.h
@@ -50,6 +50,8 @@ union xfs_btree_key {
 	struct xfs_rmap_key		rmap;
 	struct xfs_rmap_key		__rmap_bigkey[2];
 	struct xfs_refcount_key		refc;
+	struct xfs_rtrmap_key		rtrmap;
+	struct xfs_rtrmap_key		__rtrmap_bigkey[2];
 };
 
 union xfs_btree_rec {
@@ -59,6 +61,7 @@ union xfs_btree_rec {
 	struct xfs_inobt_rec		inobt;
 	struct xfs_rmap_rec		rmap;
 	struct xfs_refcount_rec		refc;
+	struct xfs_rtrmap_rec		rtrmap;
 };
 
 /*
diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
index 6afaee2..7f30781 100644
--- a/fs/xfs/libxfs/xfs_format.h
+++ b/fs/xfs/libxfs/xfs_format.h
@@ -1470,6 +1470,54 @@ typedef __be32 xfs_rmap_ptr_t;
 #define	XFS_RTRMAP_CRC_MAGIC	0x4d415052	/* 'MAPR' */
 
 /*
+ * Data record structure
+ */
+struct xfs_rtrmap_rec {
+	__be64		rm_startblock;	/* extent start block */
+	__be64		rm_blockcount;	/* extent length */
+	__be64		rm_owner;	/* extent owner */
+	__be64		rm_offset;	/* offset within the owner */
+};
+
+/* rm_offset has the same values as the regular rmapbt. */
+#define XFS_RTRMAP_OFF_ATTR_FORK	XFS_RMAP_OFF_ATTR_FORK
+#define XFS_RTRMAP_OFF_BMBT_BLOCK	XFS_RMAP_OFF_BMBT_BLOCK
+#define XFS_RTRMAP_OFF_UNWRITTEN	XFS_RMAP_OFF_UNWRITTEN
+
+#define XFS_RTRMAP_LEN_MAX		((__uint64_t)~0U)
+#define XFS_RTRMAP_OFF_FLAGS		XFS_RMAP_OFF_FLAGS
+#define XFS_RTRMAP_OFF_MASK		XFS_RMAP_OFF_MASK
+
+#define XFS_RTRMAP_OFF			XFS_RMAP_OFF
+
+#define XFS_RTRMAP_IS_BMBT_BLOCK(off)	XFS_RMAP_IS_BMBT_BLOCK
+#define XFS_RTRMAP_IS_ATTR_FORK(off)	XFS_RMAP_IS_ATTR_FORK
+#define XFS_RTRMAP_IS_UNWRITTEN(len)	XFS_RMAP_IS_UNWRITTEN
+
+#define RTRMAPBT_STARTBLOCK_BITLEN	64
+#define RTRMAPBT_BLOCKCOUNT_BITLEN	64
+#define RTRMAPBT_OWNER_BITLEN		RMAPBT_OWNER_BITLEN
+#define RTRMAPBT_ATTRFLAG_BITLEN	RMAPBT_ATTRFLAG_BITLEN
+#define RTRMAPBT_BMBTFLAG_BITLEN	RMAPBT_BMBTFLAG_BITLEN
+#define RTRMAPBT_EXNTFLAG_BITLEN	RMAPBT_EXNTFLAG_BITLEN
+#define RTRMAPBT_UNUSED_OFFSET_BITLEN	RMAPBT_UNUSED_OFFSET_BITLEN
+#define RTRMAPBT_OFFSET_BITLEN		RMAPBT_OFFSET_BITLEN
+
+/*
+ * Key structure
+ *
+ * We don't use the length for lookups
+ */
+struct xfs_rtrmap_key {
+	__be64		rm_startblock;	/* extent start block */
+	__be64		rm_owner;	/* extent owner */
+	__be64		rm_offset;	/* offset within the owner */
+} __attribute__((packed));
+
+/* btree pointer type */
+typedef __be64 xfs_rtrmap_ptr_t;
+
+/*
  * Reference Count Btree format definitions
  *
  */
diff --git a/fs/xfs/libxfs/xfs_rtrmap_btree.c b/fs/xfs/libxfs/xfs_rtrmap_btree.c
new file mode 100644
index 0000000..5008906
--- /dev/null
+++ b/fs/xfs/libxfs/xfs_rtrmap_btree.c
@@ -0,0 +1,197 @@
+/*
+ * Copyright (C) 2016 Oracle.  All Rights Reserved.
+ *
+ * Author: Darrick J. Wong <darrick.wong@oracle.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation,
+ * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+#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_rtrmap_btree.h"
+#include "xfs_trace.h"
+#include "xfs_cksum.h"
+#include "xfs_error.h"
+#include "xfs_extent_busy.h"
+#include "xfs_ag_resv.h"
+
+/*
+ * Realtime Reverse map btree.
+ *
+ * This is a per-ag tree used to track the owner(s) of a given extent
+ * in the realtime device.  See the comments in xfs_rmap_btree.c for
+ * more information.
+ *
+ * This tree is basically the same as the regular rmap btree except that
+ * it doesn't live in free space, and the startblock and blockcount
+ * fields have been widened to 64 bits.
+ */
+
+static struct xfs_btree_cur *
+xfs_rtrmapbt_dup_cursor(
+	struct xfs_btree_cur	*cur)
+{
+	struct xfs_btree_cur	*new;
+
+	new = xfs_rtrmapbt_init_cursor(cur->bc_mp, cur->bc_tp,
+			cur->bc_private.b.ip);
+
+	/*
+	 * Copy the firstblock, dfops, and flags values,
+	 * since init cursor doesn't get them.
+	 */
+	new->bc_private.b.firstblock = cur->bc_private.b.firstblock;
+	new->bc_private.b.dfops = cur->bc_private.b.dfops;
+	new->bc_private.b.flags = cur->bc_private.b.flags;
+
+	return new;
+}
+
+static bool
+xfs_rtrmapbt_verify(
+	struct xfs_buf		*bp)
+{
+	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
+	int			level;
+
+	if (block->bb_magic != cpu_to_be32(XFS_RTRMAP_CRC_MAGIC))
+		return false;
+
+	if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
+		return false;
+	if (!xfs_btree_lblock_v5hdr_verify(bp, XFS_RMAP_OWN_UNKNOWN))
+		return false;
+	level = be16_to_cpu(block->bb_level);
+	if (level > mp->m_rtrmap_maxlevels)
+		return false;
+
+	return xfs_btree_lblock_verify(bp, mp->m_rtrmap_mxr[level != 0]);
+}
+
+static void
+xfs_rtrmapbt_read_verify(
+	struct xfs_buf	*bp)
+{
+	if (!xfs_btree_lblock_verify_crc(bp))
+		xfs_buf_ioerror(bp, -EFSBADCRC);
+	else if (!xfs_rtrmapbt_verify(bp))
+		xfs_buf_ioerror(bp, -EFSCORRUPTED);
+
+	if (bp->b_error) {
+		trace_xfs_btree_corrupt(bp, _RET_IP_);
+		xfs_verifier_error(bp);
+	}
+}
+
+static void
+xfs_rtrmapbt_write_verify(
+	struct xfs_buf	*bp)
+{
+	if (!xfs_rtrmapbt_verify(bp)) {
+		trace_xfs_btree_corrupt(bp, _RET_IP_);
+		xfs_buf_ioerror(bp, -EFSCORRUPTED);
+		xfs_verifier_error(bp);
+		return;
+	}
+	xfs_btree_lblock_calc_crc(bp);
+
+}
+
+const struct xfs_buf_ops xfs_rtrmapbt_buf_ops = {
+	.name			= "xfs_rtrmapbt",
+	.verify_read		= xfs_rtrmapbt_read_verify,
+	.verify_write		= xfs_rtrmapbt_write_verify,
+};
+
+static const struct xfs_btree_ops xfs_rtrmapbt_ops = {
+	.rec_len		= sizeof(struct xfs_rtrmap_rec),
+	.key_len		= 2 * sizeof(struct xfs_rtrmap_key),
+
+	.dup_cursor		= xfs_rtrmapbt_dup_cursor,
+	.buf_ops		= &xfs_rtrmapbt_buf_ops,
+};
+
+/*
+ * Allocate a new allocation btree cursor.
+ */
+struct xfs_btree_cur *
+xfs_rtrmapbt_init_cursor(
+	struct xfs_mount	*mp,
+	struct xfs_trans	*tp,
+	struct xfs_inode	*ip)
+{
+	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
+	struct xfs_btree_cur	*cur;
+
+	cur = kmem_zone_zalloc(xfs_btree_cur_zone, KM_NOFS);
+	cur->bc_tp = tp;
+	cur->bc_mp = mp;
+	cur->bc_btnum = XFS_BTNUM_RTRMAP;
+	cur->bc_flags = XFS_BTREE_LONG_PTRS | XFS_BTREE_ROOT_IN_INODE |
+			XFS_BTREE_CRC_BLOCKS | XFS_BTREE_IROOT_RECORDS |
+			XFS_BTREE_OVERLAPPING;
+	cur->bc_blocklog = mp->m_sb.sb_blocklog;
+	cur->bc_ops = &xfs_rtrmapbt_ops;
+	cur->bc_nlevels = be16_to_cpu(ifp->if_broot->bb_level) + 1;
+
+	cur->bc_private.b.forksize = XFS_IFORK_SIZE(ip, XFS_DATA_FORK);
+	cur->bc_private.b.ip = ip;
+	cur->bc_private.b.firstblock = NULLFSBLOCK;
+	cur->bc_private.b.dfops = NULL;
+	cur->bc_private.b.allocated = 0;
+	cur->bc_private.b.flags = 0;
+	cur->bc_private.b.whichfork = XFS_DATA_FORK;
+
+	return cur;
+}
+
+/*
+ * Calculate number of records in an rmap btree block.
+ */
+int
+xfs_rtrmapbt_maxrecs(
+	struct xfs_mount	*mp,
+	int			blocklen,
+	bool			leaf)
+{
+	blocklen -= XFS_RTRMAP_BLOCK_LEN;
+
+	if (leaf)
+		return blocklen / sizeof(struct xfs_rtrmap_rec);
+	return blocklen /
+		(2 * sizeof(struct xfs_rtrmap_key) + sizeof(xfs_rtrmap_ptr_t));
+}
+
+/* Compute the maximum height of an rmap btree. */
+void
+xfs_rtrmapbt_compute_maxlevels(
+	struct xfs_mount		*mp)
+{
+	mp->m_rtrmap_maxlevels = xfs_btree_compute_maxlevels(mp,
+			mp->m_rtrmap_mnr, mp->m_sb.sb_rblocks);
+	ASSERT(mp->m_rtrmap_maxlevels <= XFS_BTREE_MAXLEVELS);
+}
diff --git a/fs/xfs/libxfs/xfs_rtrmap_btree.h b/fs/xfs/libxfs/xfs_rtrmap_btree.h
new file mode 100644
index 0000000..5eb19f4
--- /dev/null
+++ b/fs/xfs/libxfs/xfs_rtrmap_btree.h
@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2016 Oracle.  All Rights Reserved.
+ *
+ * Author: Darrick J. Wong <darrick.wong@oracle.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation,
+ * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+#ifndef __XFS_RTRMAP_BTREE_H__
+#define	__XFS_RTRMAP_BTREE_H__
+
+struct xfs_buf;
+struct xfs_btree_cur;
+struct xfs_mount;
+
+/* rmaps only exist on crc enabled filesystems */
+#define XFS_RTRMAP_BLOCK_LEN	XFS_BTREE_LBLOCK_CRC_LEN
+
+/*
+ * Record, key, and pointer address macros for btree blocks.
+ *
+ * (note that some of these may appear unused, but they are used in userspace)
+ */
+#define XFS_RTRMAP_REC_ADDR(block, index) \
+	((struct xfs_rtrmap_rec *) \
+		((char *)(block) + XFS_RTRMAP_BLOCK_LEN + \
+		 (((index) - 1) * sizeof(struct xfs_rtrmap_rec))))
+
+#define XFS_RTRMAP_KEY_ADDR(block, index) \
+	((struct xfs_rtrmap_key *) \
+		((char *)(block) + XFS_RTRMAP_BLOCK_LEN + \
+		 ((index) - 1) * 2 * sizeof(struct xfs_rtrmap_key)))
+
+#define XFS_RTRMAP_HIGH_KEY_ADDR(block, index) \
+	((struct xfs_rtrmap_key *) \
+		((char *)(block) + XFS_RTRMAP_BLOCK_LEN + \
+		 sizeof(struct xfs_rtrmap_key) + \
+		 ((index) - 1) * 2 * sizeof(struct xfs_rtrmap_key)))
+
+#define XFS_RTRMAP_PTR_ADDR(block, index, maxrecs) \
+	((xfs_rtrmap_ptr_t *) \
+		((char *)(block) + XFS_RTRMAP_BLOCK_LEN + \
+		 (maxrecs) * 2 * sizeof(struct xfs_rtrmap_key) + \
+		 ((index) - 1) * sizeof(xfs_rtrmap_ptr_t)))
+
+struct xfs_btree_cur *xfs_rtrmapbt_init_cursor(struct xfs_mount *mp,
+				struct xfs_trans *tp, struct xfs_inode *ip);
+int xfs_rtrmapbt_maxrecs(struct xfs_mount *mp, int blocklen, bool leaf);
+extern void xfs_rtrmapbt_compute_maxlevels(struct xfs_mount *mp);
+
+#endif	/* __XFS_RTRMAP_BTREE_H__ */
diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
index a937071..eb33ec9 100644
--- a/fs/xfs/libxfs/xfs_sb.c
+++ b/fs/xfs/libxfs/xfs_sb.c
@@ -40,6 +40,7 @@
 #include "xfs_rmap_btree.h"
 #include "xfs_bmap.h"
 #include "xfs_refcount_btree.h"
+#include "xfs_rtrmap_btree.h"
 
 /*
  * Physical superblock buffer manipulations. Shared with libxfs in userspace.
@@ -742,6 +743,11 @@ xfs_sb_mount_common(
 	mp->m_rmap_mnr[0] = mp->m_rmap_mxr[0] / 2;
 	mp->m_rmap_mnr[1] = mp->m_rmap_mxr[1] / 2;
 
+	mp->m_rtrmap_mxr[0] = xfs_rtrmapbt_maxrecs(mp, sbp->sb_blocksize, 1);
+	mp->m_rtrmap_mxr[1] = xfs_rtrmapbt_maxrecs(mp, sbp->sb_blocksize, 0);
+	mp->m_rtrmap_mnr[0] = mp->m_rtrmap_mxr[0] / 2;
+	mp->m_rtrmap_mnr[1] = mp->m_rtrmap_mxr[1] / 2;
+
 	mp->m_refc_mxr[0] = xfs_refcountbt_maxrecs(mp, sbp->sb_blocksize,
 			true);
 	mp->m_refc_mxr[1] = xfs_refcountbt_maxrecs(mp, sbp->sb_blocksize,
diff --git a/fs/xfs/libxfs/xfs_shared.h b/fs/xfs/libxfs/xfs_shared.h
index c6f4eb4..0032a8c 100644
--- a/fs/xfs/libxfs/xfs_shared.h
+++ b/fs/xfs/libxfs/xfs_shared.h
@@ -39,6 +39,7 @@ extern const struct xfs_buf_ops xfs_agf_buf_ops;
 extern const struct xfs_buf_ops xfs_agfl_buf_ops;
 extern const struct xfs_buf_ops xfs_allocbt_buf_ops;
 extern const struct xfs_buf_ops xfs_rmapbt_buf_ops;
+extern const struct xfs_buf_ops xfs_rtrmapbt_buf_ops;
 extern const struct xfs_buf_ops xfs_refcountbt_buf_ops;
 extern const struct xfs_buf_ops xfs_attr3_leaf_buf_ops;
 extern const struct xfs_buf_ops xfs_attr3_rmt_buf_ops;
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 039b5be..2af9b2a 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -46,6 +46,7 @@
 #include "xfs_refcount_btree.h"
 #include "xfs_reflink.h"
 #include "xfs_refcount_btree.h"
+#include "xfs_rtrmap_btree.h"
 
 
 static DEFINE_MUTEX(xfs_uuid_table_mutex);
@@ -687,6 +688,7 @@ xfs_mountfs(
 	xfs_bmap_compute_maxlevels(mp, XFS_ATTR_FORK);
 	xfs_ialloc_compute_maxlevels(mp);
 	xfs_rmapbt_compute_maxlevels(mp);
+	xfs_rtrmapbt_compute_maxlevels(mp);
 	xfs_refcountbt_compute_maxlevels(mp);
 
 	xfs_set_maxicount(mp);
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index b896ea5..70d3cc3 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -118,12 +118,15 @@ typedef struct xfs_mount {
 	uint			m_inobt_mnr[2];	/* min inobt btree records */
 	uint			m_rmap_mxr[2];	/* max rmap btree records */
 	uint			m_rmap_mnr[2];	/* min rmap btree records */
+	uint			m_rtrmap_mxr[2]; /* max rtrmap btree records */
+	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_ag_maxlevels;	/* XFS_AG_MAXLEVELS */
 	uint			m_bm_maxlevels[2]; /* XFS_BM_MAXLEVELS */
 	uint			m_in_maxlevels;	/* max inobt 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 */
 	xfs_extlen_t		m_ag_prealloc_blocks; /* reserved ag blocks */
 	uint			m_alloc_set_aside; /* space we can't use */
diff --git a/fs/xfs/xfs_ondisk.h b/fs/xfs/xfs_ondisk.h
index 0c381d7..88c771e 100644
--- a/fs/xfs/xfs_ondisk.h
+++ b/fs/xfs/xfs_ondisk.h
@@ -53,6 +53,8 @@ xfs_check_ondisk_structs(void)
 	XFS_CHECK_STRUCT_SIZE(struct xfs_refcount_rec,		12);
 	XFS_CHECK_STRUCT_SIZE(struct xfs_rmap_key,		20);
 	XFS_CHECK_STRUCT_SIZE(struct xfs_rmap_rec,		24);
+	XFS_CHECK_STRUCT_SIZE(struct xfs_rtrmap_key,		24);
+	XFS_CHECK_STRUCT_SIZE(struct xfs_rtrmap_rec,		32);
 	XFS_CHECK_STRUCT_SIZE(struct xfs_timestamp,		8);
 	XFS_CHECK_STRUCT_SIZE(xfs_alloc_key_t,			8);
 	XFS_CHECK_STRUCT_SIZE(xfs_alloc_ptr_t,			4);
