3 files changed, 81 insertions, 4 deletions
diff --git a/tools/testing/selftests/ublk/Makefile b/tools/testing/selftests/ublk/Makefile
index 799cdcc39643..c453cd369088 100644
--- a/tools/testing/selftests/ublk/Makefile
+++ b/tools/testing/selftests/ublk/Makefile
@@ -54,6 +54,7 @@ TEST_PROGS += test_part_02.sh
 
 TEST_PROGS += test_shmemzc_01.sh
 TEST_PROGS += test_shmemzc_02.sh
+TEST_PROGS += test_shmemzc_03.sh
 
 TEST_PROGS += test_stress_01.sh
 TEST_PROGS += test_stress_02.sh
diff --git a/tools/testing/selftests/ublk/test_common.sh b/tools/testing/selftests/ublk/test_common.sh
index 163a40007910..af2ea4fa1111 100755
--- a/tools/testing/selftests/ublk/test_common.sh
+++ b/tools/testing/selftests/ublk/test_common.sh
@@ -88,6 +88,7 @@ _remove_tmp_dir() {
 _mkfs_mount_test()
 {
 	local dev=$1
+	shift
 	local err_code=0
 	local mnt_dir;
 
@@ -99,12 +100,17 @@ _mkfs_mount_test()
 	fi
 
 	mount -t ext4 "$dev" "$mnt_dir" > /dev/null 2>&1
+	if [ $# -gt 0 ]; then
+		cd "$mnt_dir" && "$@"
+		err_code=$?
+		cd - > /dev/null
+	fi
 	umount "$dev"
-	err_code=$?
-	_remove_tmp_dir "$mnt_dir"
-	if [ $err_code -ne 0 ]; then
-		return $err_code
+	if [ $err_code -eq 0 ]; then
+		err_code=$?
 	fi
+	_remove_tmp_dir "$mnt_dir"
+	return $err_code
 }
 
 _check_root() {
@@ -132,6 +138,7 @@ _prep_test() {
 	local base_dir=${TMPDIR:-./ublktest-dir}
 	mkdir -p "$base_dir"
 	UBLK_TEST_DIR=$(mktemp -d ${base_dir}/${TID}.XXXXXX)
+	UBLK_TEST_DIR=$(realpath ${UBLK_TEST_DIR})
 	UBLK_TMP=$(mktemp ${UBLK_TEST_DIR}/ublk_test_XXXXX)
 	[ "$UBLK_TEST_QUIET" -eq 0 ] && echo "ublk $type: $*"
 	echo "ublk selftest: $TID starting at $(date '+%F %T')" | tee /dev/kmsg
diff --git a/tools/testing/selftests/ublk/test_shmemzc_03.sh b/tools/testing/selftests/ublk/test_shmemzc_03.sh
new file mode 100755
index 000000000000..db967a9ffe81
--- /dev/null
+++ b/tools/testing/selftests/ublk/test_shmemzc_03.sh
@@ -0,0 +1,69 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Test: shmem_zc with fio verify over filesystem on loop target
+#
+# mkfs + mount ext4 on the ublk device, then run fio verify on a
+# file inside that filesystem.  Exercises the full stack:
+# filesystem -> block layer -> ublk shmem_zc -> loop target backing file.
+
+. "$(cd "$(dirname "$0")" && pwd)"/test_common.sh
+
+ERR_CODE=0
+
+_prep_test "shmem_zc" "loop target hugetlbfs shmem zero-copy fs verify test"
+
+if ! _have_program fio; then
+	echo "SKIP: fio not available"
+	exit "$UBLK_SKIP_CODE"
+fi
+
+if ! grep -q hugetlbfs /proc/filesystems; then
+	echo "SKIP: hugetlbfs not supported"
+	exit "$UBLK_SKIP_CODE"
+fi
+
+# Allocate hugepages
+OLD_NR_HP=$(cat /proc/sys/vm/nr_hugepages)
+echo 10 > /proc/sys/vm/nr_hugepages
+NR_HP=$(cat /proc/sys/vm/nr_hugepages)
+if [ "$NR_HP" -lt 2 ]; then
+	echo "SKIP: cannot allocate hugepages"
+	echo "$OLD_NR_HP" > /proc/sys/vm/nr_hugepages
+	exit "$UBLK_SKIP_CODE"
+fi
+
+# Mount hugetlbfs
+HTLB_MNT=$(mktemp -d "${UBLK_TEST_DIR}/htlb_mnt_XXXXXX")
+if ! mount -t hugetlbfs none "$HTLB_MNT"; then
+	echo "SKIP: cannot mount hugetlbfs"
+	rmdir "$HTLB_MNT"
+	echo "$OLD_NR_HP" > /proc/sys/vm/nr_hugepages
+	exit "$UBLK_SKIP_CODE"
+fi
+
+HTLB_FILE="$HTLB_MNT/ublk_buf"
+fallocate -l 4M "$HTLB_FILE"
+
+_create_backfile 0 256M
+BACKFILE="${UBLK_BACKFILES[0]}"
+
+dev_id=$(_add_ublk_dev -t loop --shmem_zc --htlb "$HTLB_FILE" "$BACKFILE")
+_check_add_dev $TID $?
+
+_mkfs_mount_test /dev/ublkb"${dev_id}" \
+	_run_fio_verify_io --filename=testfile \
+		--size=128M \
+		--mem=mmaphuge:"$HTLB_FILE"
+ERR_CODE=$?
+
+# Delete device first so daemon releases the htlb mmap
+_ublk_del_dev "${dev_id}"
+
+rm -f "$HTLB_FILE"
+umount "$HTLB_MNT"
+rmdir "$HTLB_MNT"
+echo "$OLD_NR_HP" > /proc/sys/vm/nr_hugepages
+
+_cleanup_test "shmem_zc"
+
+_show_result $TID $ERR_CODE