diff --git a/tests/xfs/523 b/tests/xfs/523
new file mode 100755
index 00000000..4f5b3584
--- /dev/null
+++ b/tests/xfs/523
@@ -0,0 +1,176 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2020 Chandan Babu R.  All Rights Reserved.
+#
+# FS QA Test 523
+#
+# Verify that XFS does not cause inode fork's extent count to overflow when
+# adding a single extent while there's no possibility of splitting an existing
+# mapping (limited to realtime files only).
+#
+seq=`basename $0`
+seqres=$RESULT_DIR/$seq
+echo "QA output created by $seq"
+
+here=`pwd`
+tmp=/tmp/$$
+status=1	# failure is the default!
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+_cleanup()
+{
+	cd /
+	_scratch_unmount >> $seqres.full 2>&1
+	test -e "$rtdev" && losetup -d $rtdev >> $seqres.full 2>&1
+	rm -f $tmp.* $TEST_DIR/$seq.rtvol
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+. ./common/inject
+
+# remove previous $seqres.full before test
+rm -f $seqres.full
+
+# real QA test starts here
+
+_supported_fs xfs
+_require_test
+_require_xfs_debug
+_require_test_program "punch-alternating"
+_require_xfs_io_error_injection "reduce_max_iextents"
+_require_xfs_io_error_injection "bmap_alloc_minlen_extent"
+_require_scratch_nocheck
+
+grow_rtinodes()
+{
+	echo "* Test extending rt inodes"
+
+	_scratch_mkfs | _filter_mkfs >> $seqres.full 2> $tmp.mkfs
+	. $tmp.mkfs
+
+	echo "Create fake rt volume"
+	nr_bitmap_blks=25
+	nr_bits=$((nr_bitmap_blks * dbsize * 8))
+	rtextsz=$dbsize
+	rtdevsz=$((nr_bits * rtextsz))
+	truncate -s $rtdevsz $TEST_DIR/$seq.rtvol
+	rtdev=$(_create_loop_device $TEST_DIR/$seq.rtvol)
+
+	echo "Format and mount rt volume"
+	export USE_EXTERNAL=yes
+	export SCRATCH_RTDEV=$rtdev
+	_scratch_mkfs -d size=$((1024 * 1024 * 1024)) \
+		      -r size=2M,extsize=${rtextsz} >> $seqres.full
+	_scratch_mount >> $seqres.full
+
+	testfile=$SCRATCH_MNT/testfile
+
+	echo "Consume free space"
+	dd if=/dev/zero of=${testfile} bs=${dbsize} >> $seqres.full 2>&1
+	sync
+
+	echo "Create fragmented filesystem"
+	$here/src/punch-alternating $testfile >> $seqres.full
+	sync
+
+	echo "Inject reduce_max_iextents error tag"
+	xfs_io -x -c 'inject reduce_max_iextents' $SCRATCH_MNT
+
+	echo "Inject bmap_alloc_minlen_extent error tag"
+	xfs_io -x -c 'inject bmap_alloc_minlen_extent' $SCRATCH_MNT
+
+	echo "Grow realtime volume"
+	xfs_growfs -r $SCRATCH_MNT >> $seqres.full 2>&1
+	if [[ $? == 0 ]]; then
+		echo "Growfs succeeded; should have failed."
+		exit 1
+	fi
+
+	_scratch_unmount >> $seqres.full
+
+	echo "Verify rbmino's and rsumino's extent count"
+	for rtino in rbmino rsumino; do
+		ino=$(_scratch_xfs_db -c sb -c "print $rtino")
+		ino=${ino##${rtino} = }
+		echo "$rtino = $ino" >> $seqres.full
+
+		nextents=$(_scratch_get_iext_count $ino data || \
+				_fail "Unable to obtain inode fork's extent count")
+		if (( $nextents > 10 )); then
+			echo "Extent count overflow check failed: nextents = $nextents"
+			exit 1
+		fi
+	done
+
+	echo "Check filesystem"
+	_check_xfs_filesystem $SCRATCH_DEV none $rtdev
+
+	losetup -d $rtdev
+	rm -f $TEST_DIR/$seq.rtvol
+
+	export USE_EXTERNAL=""
+	export SCRATCH_RTDEV=""
+}
+
+rtfile_extend()
+{
+	echo "* Test extending an rt file"
+
+	_scratch_mkfs | _filter_mkfs >> $seqres.full 2> $tmp.mkfs
+	. $tmp.mkfs
+
+	echo "Create fake rt volume"
+	nr_blks=$((15 * 2))
+	rtextsz=$dbsize
+	rtdevsz=$((2 * nr_blks * rtextsz))
+	truncate -s $rtdevsz $TEST_DIR/$seq.rtvol
+	rtdev=$(_create_loop_device $TEST_DIR/$seq.rtvol)
+
+	echo "Format and mount rt volume"
+	export USE_EXTERNAL=yes
+	export SCRATCH_RTDEV=$rtdev
+	_scratch_mkfs -d size=$((1024 * 1024 * 1024)) \
+		      -r size=$rtdevsz >> $seqres.full
+	_scratch_mount >> $seqres.full
+
+	echo "Inject reduce_max_iextents error tag"
+	xfs_io -x -c 'inject reduce_max_iextents' $SCRATCH_MNT
+
+	echo "Create fragmented file on rt volume"
+	testfile=$SCRATCH_MNT/testfile
+	for i in $(seq 0 2 $((nr_blks - 1))); do
+		xfs_io -Rf -c "pwrite $((i * dbsize)) $dbsize" -c fsync \
+		       $testfile >> $seqres.full 2>&1
+		[[ $? != 0 ]] && break
+	done
+
+	testino=$(stat -c "%i" $testfile)
+
+	_scratch_unmount >> $seqres.full
+
+	echo "Verify \$testfile's extent count"
+	nextents=$(_scratch_get_iext_count $testino data || \
+			_fail "Unable to obtain inode fork's extent count")
+	if (( $nextents > 10 )); then
+		echo "Extent count overflow check failed: nextents = $nextents"
+		exit 1
+	fi
+
+	echo "Check filesystem"
+	_check_xfs_filesystem $SCRATCH_DEV none $rtdev
+
+	losetup -d $rtdev
+	rm -f $TEST_DIR/$seq.rtvol
+
+	export USE_EXTERNAL=""
+	export SCRATCH_RTDEV=""
+}
+
+grow_rtinodes
+rtfile_extend
+
+# success, all done
+status=0
+exit
diff --git a/tests/xfs/523.out b/tests/xfs/523.out
new file mode 100644
index 00000000..16b4e0ad
--- /dev/null
+++ b/tests/xfs/523.out
@@ -0,0 +1,18 @@
+QA output created by 523
+* Test extending rt inodes
+Create fake rt volume
+Format and mount rt volume
+Consume free space
+Create fragmented filesystem
+Inject reduce_max_iextents error tag
+Inject bmap_alloc_minlen_extent error tag
+Grow realtime volume
+Verify rbmino's and rsumino's extent count
+Check filesystem
+* Test extending an rt file
+Create fake rt volume
+Format and mount rt volume
+Inject reduce_max_iextents error tag
+Create fragmented file on rt volume
+Verify $testfile's extent count
+Check filesystem
diff --git a/tests/xfs/group b/tests/xfs/group
index 1831f0b5..018c70ef 100644
--- a/tests/xfs/group
+++ b/tests/xfs/group
@@ -520,3 +520,4 @@
 520 auto quick reflink
 521 auto quick realtime growfs
 522 auto quick quota
+523 auto quick realtime growfs
