Commit affb5f67 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

selftests/ublk: add read-only buffer registration test 



Add --rdonly_shmem_buf option to kublk that registers shared memory
buffers with UBLK_SHMEM_BUF_READ_ONLY (read-only pinning without
FOLL_WRITE) and mmaps with PROT_READ only.

Add test_shmemzc_04.sh which exercises the new flag with a null target,
hugetlbfs buffer, and write workload. Write I/O works because the
server only reads from the shared buffer — the data flows from client
to kernel to the shared pages, and the server reads them out.

Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Link: https://patch.msgid.link/20260331153207.3635125-11-ming.lei@redhat.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 12075992

tools/testing/selftests/ublk/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -55,6 +55,7 @@ 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_shmemzc_04.sh



TEST_PROGS += test_stress_01.sh

TEST_PROGS += test_stress_02.sh

tools/testing/selftests/ublk/kublk.c

+11 −4
Original line number Diff line number Diff line
@@ -1219,11 +1219,13 @@ static void ublk_shmem_unregister_all(void) 
	shmem_count = 0;

}



static int ublk_ctrl_reg_buf(struct ublk_dev *dev, void *addr, size_t size)

static int ublk_ctrl_reg_buf(struct ublk_dev *dev, void *addr, size_t size,

			     __u32 flags)

{

	struct ublk_shmem_buf_reg buf_reg = {

		.addr = (unsigned long)addr,

		.len = size,

		.flags = flags,

	};

	struct ublk_ctrl_cmd_data data = {

		.cmd_op = UBLK_U_CMD_REG_BUF,
@@ -1272,7 +1274,7 @@ static void ublk_shmem_handle_client(int sock_fd, struct ublk_dev *dev) 
	}



	/* Register server's VA range with kernel for PFN matching */

	ret = ublk_ctrl_reg_buf(dev, base, size);

	ret = ublk_ctrl_reg_buf(dev, base, size, 0);

	if (ret < 0) {

		ublk_dbg(UBLK_DBG_DEV,

			 "shmem_zc: kernel reg failed %d\n", ret);
@@ -1357,7 +1359,8 @@ static int ublk_shmem_htlb_setup(const struct dev_ctx *ctx, 
		return -EINVAL;

	}



	base = mmap(NULL, st.st_size, PROT_READ | PROT_WRITE,

	base = mmap(NULL, st.st_size,

		    ctx->rdonly_shmem_buf ? PROT_READ : PROT_READ | PROT_WRITE,

		    MAP_SHARED | MAP_POPULATE, fd, 0);

	if (base == MAP_FAILED) {

		ublk_err("htlb: mmap failed\n");
@@ -1365,7 +1368,8 @@ static int ublk_shmem_htlb_setup(const struct dev_ctx *ctx, 
		return -ENOMEM;

	}



	ret = ublk_ctrl_reg_buf(dev, base, st.st_size);

	ret = ublk_ctrl_reg_buf(dev, base, st.st_size,

			       ctx->rdonly_shmem_buf ? UBLK_SHMEM_BUF_READ_ONLY : 0);

	if (ret < 0) {

		ublk_err("htlb: reg_buf failed: %d\n", ret);

		munmap(base, st.st_size);
@@ -2129,6 +2133,7 @@ int main(int argc, char *argv[]) 
		{ "no_auto_part_scan",	0,	NULL,  0 },

		{ "shmem_zc",		0,	NULL,  0  },

		{ "htlb",		1,	NULL,  0  },

		{ "rdonly_shmem_buf",	0,	NULL,  0  },

		{ 0, 0, 0, 0 }

	};

	const struct ublk_tgt_ops *ops = NULL;
@@ -2248,6 +2253,8 @@ int main(int argc, char *argv[]) 
				ctx.flags |= UBLK_F_SHMEM_ZC;

			if (!strcmp(longopts[option_idx].name, "htlb"))

				ctx.htlb_path = strdup(optarg);

			if (!strcmp(longopts[option_idx].name, "rdonly_shmem_buf"))

				ctx.rdonly_shmem_buf = 1;

			break;

		case '?':

			/*

tools/testing/selftests/ublk/kublk.h

+1 −0
Original line number Diff line number Diff line
@@ -81,6 +81,7 @@ struct dev_ctx { 
	unsigned int	no_ublk_fixed_fd:1;

	unsigned int	safe_stop:1;

	unsigned int	no_auto_part_scan:1;

	unsigned int	rdonly_shmem_buf:1;

	__u32 integrity_flags;

	__u8 metadata_size;

	__u8 pi_offset;

tools/testing/selftests/ublk/test_shmemzc_04.sh

0 → 100755
+72 −0
Original line number Diff line number Diff line 
#!/bin/bash

# SPDX-License-Identifier: GPL-2.0

# Test: shmem_zc with read-only buffer registration on null target

#

# Same as test_shmemzc_01 but with --rdonly_shmem_buf: pages are pinned

# without FOLL_WRITE (UBLK_BUF_F_READ).  Write I/O works because

# the server only reads from the shared buffer.



. "$(cd "$(dirname "$0")" && pwd)"/test_common.sh



ERR_CODE=0



_prep_test "shmem_zc" "null target hugetlbfs shmem zero-copy rdonly_buf 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"



dev_id=$(_add_ublk_dev -t null --shmem_zc --htlb "$HTLB_FILE" --rdonly_shmem_buf)

_check_add_dev $TID $?



fio --name=htlb_zc_rdonly \

	--filename=/dev/ublkb"${dev_id}" \

	--ioengine=io_uring \

	--rw=randwrite \

	--direct=1 \

	--bs=4k \

	--size=4M \

	--iodepth=32 \

	--mem=mmaphuge:"$HTLB_FILE" \

	> /dev/null 2>&1

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