Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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: Ming Lei <ming.lei@redhat.com>
Link: https://patch.msgid.link/20260331153207.3635125-11-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
authored by
Ming Lei
and committed by
Jens Axboe
affb5f67
12075992
+85
-4
+1
tools/testing/selftests/ublk/Makefile
+1
tools/testing/selftests/ublk/Makefile
+11
-4
tools/testing/selftests/ublk/kublk.c
+11
-4
tools/testing/selftests/ublk/kublk.c
···
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shmem_count = 0;
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}
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-
static int ublk_ctrl_reg_buf(struct ublk_dev *dev, void *addr, size_t size)
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static int ublk_ctrl_reg_buf(struct ublk_dev *dev, void *addr, size_t size,
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__u32 flags)
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{
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struct ublk_shmem_buf_reg buf_reg = {
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.addr = (unsigned long)addr,
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.len = size,
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.flags = flags,
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};
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struct ublk_ctrl_cmd_data data = {
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.cmd_op = UBLK_U_CMD_REG_BUF,
···
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}
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/* Register server's VA range with kernel for PFN matching */
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ret = ublk_ctrl_reg_buf(dev, base, size);
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ret = ublk_ctrl_reg_buf(dev, base, size, 0);
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if (ret < 0) {
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ublk_dbg(UBLK_DBG_DEV,
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"shmem_zc: kernel reg failed %d\n", ret);
···
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return -EINVAL;
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}
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-
base = mmap(NULL, st.st_size, PROT_READ | PROT_WRITE,
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base = mmap(NULL, st.st_size,
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ctx->rdonly_shmem_buf ? PROT_READ : PROT_READ | PROT_WRITE,
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MAP_SHARED | MAP_POPULATE, fd, 0);
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if (base == MAP_FAILED) {
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ublk_err("htlb: mmap failed\n");
···
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return -ENOMEM;
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}
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ret = ublk_ctrl_reg_buf(dev, base, st.st_size);
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ret = ublk_ctrl_reg_buf(dev, base, st.st_size,
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ctx->rdonly_shmem_buf ? UBLK_SHMEM_BUF_READ_ONLY : 0);
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if (ret < 0) {
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ublk_err("htlb: reg_buf failed: %d\n", ret);
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munmap(base, st.st_size);
···
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{ "no_auto_part_scan", 0, NULL, 0 },
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{ "shmem_zc", 0, NULL, 0 },
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{ "htlb", 1, NULL, 0 },
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{ "rdonly_shmem_buf", 0, NULL, 0 },
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{ 0, 0, 0, 0 }
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};
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const struct ublk_tgt_ops *ops = NULL;
···
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ctx.flags |= UBLK_F_SHMEM_ZC;
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if (!strcmp(longopts[option_idx].name, "htlb"))
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ctx.htlb_path = strdup(optarg);
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if (!strcmp(longopts[option_idx].name, "rdonly_shmem_buf"))
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ctx.rdonly_shmem_buf = 1;
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break;
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case '?':
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/*
+1
tools/testing/selftests/ublk/kublk.h
+1
tools/testing/selftests/ublk/kublk.h
+72
tools/testing/selftests/ublk/test_shmemzc_04.sh
+72
tools/testing/selftests/ublk/test_shmemzc_04.sh
···
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#!/bin/bash
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# SPDX-License-Identifier: GPL-2.0
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# Test: shmem_zc with read-only buffer registration on null target
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#
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# Same as test_shmemzc_01 but with --rdonly_shmem_buf: pages are pinned
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# without FOLL_WRITE (UBLK_BUF_F_READ). Write I/O works because
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# the server only reads from the shared buffer.
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. "$(cd "$(dirname "$0")" && pwd)"/test_common.sh
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ERR_CODE=0
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_prep_test "shmem_zc" "null target hugetlbfs shmem zero-copy rdonly_buf test"
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if ! _have_program fio; then
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echo "SKIP: fio not available"
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exit "$UBLK_SKIP_CODE"
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fi
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+
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if ! grep -q hugetlbfs /proc/filesystems; then
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echo "SKIP: hugetlbfs not supported"
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exit "$UBLK_SKIP_CODE"
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fi
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+
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# Allocate hugepages
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OLD_NR_HP=$(cat /proc/sys/vm/nr_hugepages)
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echo 10 > /proc/sys/vm/nr_hugepages
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NR_HP=$(cat /proc/sys/vm/nr_hugepages)
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if [ "$NR_HP" -lt 2 ]; then
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echo "SKIP: cannot allocate hugepages"
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echo "$OLD_NR_HP" > /proc/sys/vm/nr_hugepages
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exit "$UBLK_SKIP_CODE"
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fi
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# Mount hugetlbfs
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HTLB_MNT=$(mktemp -d "${UBLK_TEST_DIR}/htlb_mnt_XXXXXX")
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if ! mount -t hugetlbfs none "$HTLB_MNT"; then
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echo "SKIP: cannot mount hugetlbfs"
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rmdir "$HTLB_MNT"
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echo "$OLD_NR_HP" > /proc/sys/vm/nr_hugepages
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exit "$UBLK_SKIP_CODE"
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fi
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HTLB_FILE="$HTLB_MNT/ublk_buf"
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fallocate -l 4M "$HTLB_FILE"
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dev_id=$(_add_ublk_dev -t null --shmem_zc --htlb "$HTLB_FILE" --rdonly_shmem_buf)
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_check_add_dev $TID $?
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fio --name=htlb_zc_rdonly \
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--filename=/dev/ublkb"${dev_id}" \
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--ioengine=io_uring \
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--rw=randwrite \
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--direct=1 \
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--bs=4k \
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--size=4M \
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--iodepth=32 \
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--mem=mmaphuge:"$HTLB_FILE" \
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> /dev/null 2>&1
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ERR_CODE=$?
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# Delete device first so daemon releases the htlb mmap
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_ublk_del_dev "${dev_id}"
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rm -f "$HTLB_FILE"
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umount "$HTLB_MNT"
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rmdir "$HTLB_MNT"
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echo "$OLD_NR_HP" > /proc/sys/vm/nr_hugepages
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_cleanup_test "shmem_zc"
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_show_result $TID $ERR_CODE