[PATCH blktests v4 0/3] bcache: add initial test cases

[PATCH blktests v4 0/3] bcache: add initial test cases

[Daniel Wagner]

I've updated the v3 version with the feedback from Shinichiro for v2.
Shinichiro, please note I did rewrite some of the logic in v3, thus some of your
comments didn't apply. But hopefully I don't made a big mess :)
 
Cheers,
Daniel

[1] https://lore.kernel.org/linux-bcache/CANubcdX7eNbH_bo4-f94DUbdiEbt04Vxy1MPyhm+CZyXB01FuQ@mail.gmail.com/
 

Signed-off-by: Daniel Wagner <dwagner@suse.de>
---
Changes in v4:
- changed file mode to 755 for 001 and 002
- changed license to GPL-3.0+
- use group_requires
- fixed whitespace damage
- dropped unnecessary '|| true'
- added 'local' for local variables
- added wait loop for register interface to show up
- updated documentation
- Link to v3: https://patch.msgid.link/20260122-bcache-v3-0-2c02d15a4503@suse.de

Changes in v3:
- add bcache/002
- return created bcache devices to tests case
- made cleanup more robust (handling detached cache)
- track all resources correctly
- operatoe only in final cleanup on known devices
- Link to v2: https://patch.msgid.link/20260121-bcache-v2-0-b26af185e63a@suse.de

Changes in v2:
- fixed whitespace damage
- added documentation on how to configure for bcache tests
- do registering explicitly
- made disk wiping more robust
- Link to v1: https://patch.msgid.link/20260120-bcache-v1-1-59bf0b2d4140@suse.de

---
Daniel Wagner (3):
      bcache: add bcache/001
      bcache: add bcache/002
      doc: document how to configure bcache tests

 Documentation/running-tests.md |  10 ++
 tests/bcache/001               |  44 +++++
 tests/bcache/001.out           |   3 +
 tests/bcache/002               |  62 +++++++
 tests/bcache/002.out           |   2 +
 tests/bcache/rc                | 375 +++++++++++++++++++++++++++++++++++++++++
 6 files changed, 496 insertions(+)
---
base-commit: e387a7e0169cc012eb6a7140a0561d2901c92a76
change-id: 20260120-bcache-35ec7368c8f4

Best regards,
-- 
Daniel Wagner <dwagner@suse.de>

[PATCH blktests v4 1/3] bcache: add bcache/001

[Daniel Wagner]

So far we are missing tests for bcache. Besides a relative simple
setup/teardown tests add also the corresponding infrastructure. More
tests are to be expected to depend on this.

_create_bcache/_remove_bcache are tracking the resources and if anything
is missing it will complain.

Signed-off-by: Daniel Wagner <dwagner@suse.de>
---
 tests/bcache/001     |  44 ++++++
 tests/bcache/001.out |   3 +
 tests/bcache/rc      | 375 +++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 422 insertions(+)

diff --git a/tests/bcache/001 b/tests/bcache/001
new file mode 100755
index 000000000000..7258d87566cb
--- /dev/null
+++ b/tests/bcache/001
@@ -0,0 +1,44 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-3.0+
+# Copyright (C) 2026 Daniel Wagner, SUSE Labs
+#
+# Test bcache setup and teardown
+
+. tests/bcache/rc
+
+DESCRIPTION="test bcache setup and teardown"
+
+test_device_array() {
+	echo "Running ${TEST_NAME}"
+
+	if [[ ${#TEST_DEV_ARRAY[@]} -lt 3 ]]; then
+		SKIP_REASONS+=("requires at least 3 devices")
+		return 1
+	fi
+
+	_setup_bcache "${TEST_DEV_ARRAY[@]}"
+
+	local bcache_nodes
+
+	mapfile -t bcache_nodes < <(_create_bcache \
+				--cache "${TEST_DEV_ARRAY[0]##*/}" \
+				--bdev "${TEST_DEV_ARRAY[1]##*/}" \
+				--writeback)
+
+	echo "number of bcaches: ${#bcache_nodes[*]}"
+
+	_remove_bcache --bcache "${bcache_nodes[@]}" \
+			--cache "${TEST_DEV_ARRAY[0]##*/}" \
+			--bdev "${TEST_DEV_ARRAY[1]##*/}" \
+
+	mapfile -t bcache_nodes < <(_create_bcache \
+				--cache "${TEST_DEV_ARRAY[0]##*/}" \
+				--bdev "${TEST_DEV_ARRAY[1]##*/}" "${TEST_DEV_ARRAY[2]##*/}" \
+				--writeback)
+
+	echo "number of bcaches: ${#bcache_nodes[*]}"
+
+	_remove_bcache --bcache "${bcache_nodes[@]}" \
+			--cache "${TEST_DEV_ARRAY[0]##*/}" \
+			--bdev "${TEST_DEV_ARRAY[1]##*/}" "${TEST_DEV_ARRAY[2]##*/}"
+}
diff --git a/tests/bcache/001.out b/tests/bcache/001.out
new file mode 100644
index 000000000000..844154e13822
--- /dev/null
+++ b/tests/bcache/001.out
@@ -0,0 +1,3 @@
+Running bcache/001
+number of bcaches: 1
+number of bcaches: 2
diff --git a/tests/bcache/rc b/tests/bcache/rc
new file mode 100644
index 000000000000..cfd4094c2fe0
--- /dev/null
+++ b/tests/bcache/rc
@@ -0,0 +1,375 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-3.0+
+# Copyright (C) 2026 Daniel Wagner, SUSE Labs
+
+. common/rc
+
+declare BCACHE_DEVS_LIST
+
+BCACHE_MAX_RETRIES=5
+
+group_requires() {
+	_have_kernel_options MD BCACHE BCACHE_DEBUG AUTOFS_FS
+	_have_program make-bcache
+	_have_crypto_algorithm crc32c
+}
+
+_bcache_wipe_devs() {
+	local devs=("$@")
+	local dev
+
+	for dev in "${devs[@]}"; do
+		# Attempt a clean wipe first
+		if wipefs --all --quiet "${dev}" 2>/dev/null; then
+			continue
+		fi
+
+		# Overwrite the first 10MB to clear stubborn partition tables or metadata
+		if ! dd if=/dev/zero of="${dev}" bs=1M count=10 conv=notrunc status=none; then
+			echo "Error: dd failed on ${dev}" >&2
+		fi
+
+		# Wipe the Tail (Last 5MB)
+		# bcache often places backup superblocks at the end of the device.
+		local dev_size_mb
+		dev_size_mb=$(blockdev --getsize64 "$dev" | awk '{print int($1 / 1024 / 1024)}')
+
+		if [ "$dev_size_mb" -gt 10 ]; then
+			local seek_pos=$((dev_size_mb - 5))
+			dd if=/dev/zero of="${dev}" bs=1M count=5 seek=$seek_pos conv=fsync status=none
+		fi
+
+		# Refresh kernel partition table & wait for udev
+		partprobe "$dev" 2>/dev/null
+		udevadm settle
+
+		# Try wiping again after clearing the headers
+		if ! wipefs --all --quiet --force "${dev}"; then
+			echo "Warning: Failed to wipe ${dev} even after dd." >&2
+		fi
+	done
+}
+
+_bcache_register() {
+	local devs=("$@")
+	local dev timeout=0
+
+	while [[ ! -w /sys/fs/bcache/register ]] && (( timeout < 10 )); do
+		sleep 1
+		(( timeout ++ ))
+	done
+
+	if [[ ! -w /sys/fs/bcache/register ]]; then
+		echo "ERROR: bcache registration interface not found." >&2
+		return 1
+	fi
+
+	for dev in "${devs[@]}"; do
+		local tmp_err
+
+		tmp_err="/tmp/bcache_reg_$$.err"
+		if ! echo "${dev}" > /sys/fs/bcache/register 2> "${tmp_err}"; then
+			local err_msg
+
+			err_msg=$(< "${tmp_err}")
+			if [[ "${err_msg}" != *"Device or resource busy"* ]]; then
+				echo "ERROR: Failed to register ${dev}: ${err_msg:-"Unknown error"}" >&2
+			fi
+		fi
+		rm -f "${tmp_err}"
+	done
+}
+
+_create_bcache() {
+	local -a cdevs=()
+	local -a bdevs=()
+	local -a ARGS=()
+	local -a created_devs=()
+	local bucket_size="64k"
+	local block_size="4k"
+
+	while [[ $# -gt 0 ]]; do
+		case $1 in
+			--cache)
+				shift
+				# Collect arguments until the next flag or end of input
+				while [[ $# -gt 0 && ! $1 =~ ^-- ]]; do
+					cdevs+=("$1")
+					shift
+				done
+				;;
+			--bdev)
+				shift
+				# Collect arguments until the next flag or end of input
+				while [[ $# -gt 0 && ! $1 =~ ^-- ]]; do
+					bdevs+=("$1")
+					shift
+				done
+				;;
+			--bucket-size)
+				bucket_size="$2"
+				shift 2
+				;;
+			--block-size)
+				block_size="$2"
+				shift 2
+				;;
+			--writeback)
+				ARGS+=(--writeback)
+				shift 1
+				;;
+			--discard)
+				ARGS+=(--discard)
+				shift 1
+				;;
+			*)
+				echo "WARNING: unknown argument: $1"
+				shift
+				;;
+		esac
+	done
+
+	# add /dev prefix to device names
+	cdevs=( "${cdevs[@]/#/\/dev\/}" )
+	bdevs=( "${bdevs[@]/#/\/dev\/}" )
+
+	# make-bcache expects empty/cleared devices
+	_bcache_wipe_devs "${cdevs[@]}" "${bdevs[@]}"
+
+	local -a cmd
+	cmd=(make-bcache --wipe-bcache \
+			--bucket "${bucket_size}" \
+			--block "${block_size}")
+	for dev in "${cdevs[@]}"; do cmd+=("--cache" "${dev}"); done
+	for dev in "${bdevs[@]}"; do cmd+=("--bdev" "${dev}"); done
+	cmd+=("${ARGS[@]}")
+
+	local output rc
+	output=$("${cmd[@]}" 2>&1)
+	rc="$?"
+	if [[ "${rc}" -ne 0 ]]; then
+		echo "ERROR: make-bcache failed:" >&2
+		echo "$output" >&2
+		return 1
+	fi
+
+	local cset_uuid
+	cset_uuid=$(echo "$output" | awk '/Set UUID:/ {print $3}' | head -n 1)
+	if [[ -z "${cset_uuid}" ]]; then
+		echo "ERROR: Could not extract cset UUID from make-bcache output" >&2
+		return 1
+	fi
+
+	local -a bdev_uuids
+	mapfile -t bdev_uuids < <(echo "$output" | awk '
+	  $1 == "UUID:" { last_uuid = $2 }
+	  $1 == "version:" && $2 == "1" { print last_uuid}
+	')
+
+	_bcache_register "${cdevs[@]}" "${bdevs[@]}"
+	udevadm settle
+
+	for uuid in "${bdev_uuids[@]}"; do
+		local link found
+
+		link=/dev/bcache/by-uuid/"${uuid}"
+		found=false
+
+		for ((i=0; i<BCACHE_MAX_RETRIES; i++)); do
+			if [[ -L "${link}" ]]; then
+				created_devs+=("$(readlink -f "${link}")")
+				found=true
+				break
+			fi
+
+			# poke udev to create the links
+			udevadm trigger "block/$(basename "$(readlink -f "${link}" 2>/dev/null || echo "notfound")")" 2>/dev/null
+			sleep 1
+		done
+
+		if [[ "${found}" == "false" ]]; then
+			echo "WARNING: Could not find device node for UUID ${uuid} after ${BCACHE_MAX_RETRIES}s" >&2
+		fi
+	done
+
+	printf "%s\n" "${created_devs[@]}"
+}
+
+_remove_bcache() {
+	local -a cdevs=()
+	local -a bdevs=()
+	local -a csets=()
+	local -a bcache_devs=()
+	local uuid
+
+	while [[ $# -gt 0 ]]; do
+		case $1 in
+			--cache)
+				shift
+				# Collect arguments until the next flag or end of input
+				while [[ $# -gt 0 && ! $1 =~ ^-- ]]; do
+					cdevs+=("$1")
+					shift
+				done
+				;;
+			--bdev)
+				shift
+				# Collect arguments until the next flag or end of input
+				while [[ $# -gt 0 && ! $1 =~ ^-- ]]; do
+					bdevs+=("$1")
+					shift
+				done
+				;;
+			--bcache)
+				shift
+				# Collect arguments until the next flag or end of input
+				while [[ $# -gt 0 && ! $1 =~ ^-- ]]; do
+					bcache_devs+=("$1")
+					shift
+				done
+				;;
+			*)
+				echo "WARNING: unknown argument: $1"
+				shift
+				;;
+		esac
+	done
+
+	for dev in "${bcache_devs[@]}"; do
+		local bcache bcache_dir
+
+		if mountpoint -q "${dev}" 2>/dev/null; then
+			umount -l "${dev}"
+		fi
+
+		bcache="${dev##*/}"
+		bcache_dir=/sys/block/"${bcache}"/bcache
+		if [ -f "${bcache_dir}"/stop ]; then
+			echo 1 > "${bcache_dir}"/stop
+		fi
+	done
+
+	# The cache could be detached, thus go through all caches and
+	# look for the cdev in there.
+	local cset_path
+	for cset_path in /sys/fs/bcache/*-*-*-*-*; do
+		local cache_link match_found
+
+		match_found=false
+		for cache_link in "${cset_path}"/cache[0-9]*; do
+			local full_sys_path _cdev cdev
+
+			full_sys_path="$(readlink -f "$cache_link")"
+			_cdev="$(basename "${full_sys_path%/bcache}")"
+
+			for cdev in "${cdevs[@]}"; do
+				if [ "${_cdev}" == "$(basename "${cdev}")"  ]; then
+					match_found=true
+					break 2
+				fi
+			done
+		done
+
+		if [ "${match_found}" = false ]; then
+			continue
+		fi
+
+		cset="$(basename "${cset_path}")"
+		if [ -d /sys/fs/bcache/"${cset}" ]; then
+			echo 1 > /sys/fs/bcache/"${cset}"/unregister
+			csets+=("${cset}")
+		fi
+	done
+
+	udevadm settle
+
+	local timeout
+	for cset in "${csets[@]}"; do
+		timeout=0
+		while [[ -d /sys/fs/bcache/"${cset}" ]] && (( timeout < 10 )); do
+			sleep 0.5
+			(( timeout++ ))
+		done
+	done
+
+	_bcache_wipe_devs "${cdevs[@]}" "${bdevs[@]}"
+}
+
+_cleanup_bcache() {
+	local cset dev bcache bcache_devs cset_path
+	local -a csets=()
+
+	read -r -a bcache_devs <<< "${BCACHE_DEVS_LIST:-}"
+
+	# Don't let successive Ctrl-Cs interrupt the cleanup processes
+	trap '' SIGINT
+
+	shopt -s nullglob
+	for bcache  in /sys/block/bcache* ; do
+		[ -e "${bcache}" ] || continue
+
+		if [[ -f "${bcache}/bcache/backing_dev_name" ]]; then
+			bdev=$(basename "$(cat "${bcache}/bcache/backing_dev_name")")
+
+			for dev in "${bcache_devs[@]}"; do
+				if [[ "${bdev}" == "$(basename "${dev}")" ]]; then
+					echo "WARNING: Stopping bcache device ${bdev}"
+					echo 1 > /sys/block/"${bdev}"/bcache/stop 2>/dev/null
+					break
+				fi
+			done
+		fi
+	done
+
+	for cset_path in /sys/fs/bcache/*-*-*-*-*; do
+		local cache_link match_found
+
+		match_found=false
+		for cache_link in "${cset_path}"/cache[0-9]*; do
+			local full_sys_path cdev
+
+			full_sys_path="$(readlink -f "$cache_link")"
+			cdev="$(basename "${full_sys_path%/bcache}")"
+
+			for dev in "${bcache_devs[@]}"; do
+				if [ "${cdev}" == "$(basename "${dev}")" ]; then
+					match_found=true
+					break 2
+				fi
+			done
+		done
+
+		if [ "${match_found}" = false ]; then
+			continue
+		fi
+
+		cset="$(basename "${cset_path}")"
+		if [ -d /sys/fs/bcache/"${cset}" ]; then
+			echo "WARNING: Unregistering cset $(basename "${cset}")"
+			echo 1 > /sys/fs/bcache/"${cset}"/unregister
+			csets+=("${cset}")
+		fi
+	done
+	shopt -u nullglob
+
+	udevadm settle
+
+	local timeout
+	for cset in "${csets[@]}"; do
+		timeout=0
+		while [[ -d /sys/fs/bcache/"${cset}" ]] && (( timeout < 10 )); do
+			sleep 0.5
+			(( timeout++ ))
+		done
+	done
+
+	_bcache_wipe_devs "${bcache_devs[@]}"
+
+	trap SIGINT
+}
+
+_setup_bcache() {
+	BCACHE_DEVS_LIST="$*"
+
+	_register_test_cleanup _cleanup_bcache
+}

-- 
2.53.0

[PATCH blktests v4 2/3] bcache: add bcache/002

[Daniel Wagner]

Add test case from Stephen Zhang [1].

[1] https://lore.kernel.org/linux-bcache/CANubcdX7eNbH_bo4-f94DUbdiEbt04Vxy1MPyhm+CZyXB01FuQ@mail.gmail.com/

Signed-off-by: Daniel Wagner <dwagner@suse.de>
---
 tests/bcache/002     | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 tests/bcache/002.out |  2 ++
 2 files changed, 64 insertions(+)

diff --git a/tests/bcache/002 b/tests/bcache/002
new file mode 100755
index 000000000000..c27178a90c2d
--- /dev/null
+++ b/tests/bcache/002
@@ -0,0 +1,62 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-3.0+
+# Copyright (C) 2026 Daniel Wagner, SUSE Labs
+#
+# Test based on Stephen Zhang <starzhangzsd@gmail.com> test case
+# https://lore.kernel.org/linux-bcache/CANubcdX7eNbH_bo4-f94DUbdiEbt04Vxy1MPyhm+CZyXB01FuQ@mail.gmail.com/#t
+#
+# Test bcache for bio leaks in clone
+
+. tests/bcache/rc
+
+DESCRIPTION="test bcache for bio leaks in clone"
+
+requires() {
+	_have_fio
+	_have_program iostat
+}
+
+test_device_array() {
+	echo "Running ${TEST_NAME}"
+
+	if [[ ${#TEST_DEV_ARRAY[@]} -lt 2 ]]; then
+		SKIP_REASONS+=("requires at least 2 devices")
+		return 1
+	fi
+
+	_setup_bcache "${TEST_DEV_ARRAY[@]}"
+
+	local bcache_nodes bcache_dev bdev_name fio_pid
+
+	mapfile -t bcache_nodes < <(_create_bcache \
+				--cache "${TEST_DEV_ARRAY[0]##*/}" \
+				--bdev "${TEST_DEV_ARRAY[1]##*/}" \
+				--writeback)
+
+	bcache_dev="${bcache_nodes[0]}"
+	bdev_name="$(basename "${bcache_dev}")"
+	echo 1 > /sys/block/"${bdev_name}"/bcache/detach
+
+	state="$(cat /sys/block/"${bdev_name}"/bcache/state)"
+	echo "Device state: ${state}"
+
+	_run_fio_rand_io --filename="${bcache_dev}" --time_base \
+			--runtime=30 >> "$FULL" 2>&1 &
+	fio_pid=$!
+
+	sleep 5
+
+	local stats_line util
+	stats_line=$(iostat -x 1 2 "${bdev_name}" | grep -w "${bdev_name}" | tail -n 1)
+	util="$(echo "${stats_line}" | awk '{print $NF}')"
+
+	if (( $(echo "${util} > 1.0" | bc -l) )); then
+		echo "ERROR: Accounting leak detected!"
+	fi
+
+	{ pkill -f "fio.*${bcache_dev}"; wait "${fio_pid}"; } &> /dev/null
+
+	_remove_bcache --bcache "${bcache_nodes[@]}" \
+			--cache "${TEST_DEV_ARRAY[0]##*/}" \
+			--bdev "${TEST_DEV_ARRAY[1]##*/}"
+}
diff --git a/tests/bcache/002.out b/tests/bcache/002.out
new file mode 100644
index 000000000000..529c1a90b135
--- /dev/null
+++ b/tests/bcache/002.out
@@ -0,0 +1,2 @@
+Running bcache/002
+Device state: no cache

-- 
2.53.0

[PATCH blktests v4 3/3] doc: document how to configure bcache tests

[Daniel Wagner]

Add a bcache entry in running-tests which explains how to configure
blktests for the bcache tests.

Signed-off-by: Daniel Wagner <dwagner@suse.de>
---
 Documentation/running-tests.md | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Documentation/running-tests.md b/Documentation/running-tests.md
index f9da042bb3a0..7d935aad3331 100644
--- a/Documentation/running-tests.md
+++ b/Documentation/running-tests.md
@@ -189,6 +189,16 @@ THROTL_BLKDEV_TYPES="sdebug" ./check throtl/
 THROTL_BLKDEV_TYPES="nullb sdebug" ./check throtl/
 ```
 
+### Bcache test configuration
+
+The bcache tests require multiple devices to run simultaneously. By default,
+blktests run each test case for each device in TEST_DEVS. This behavior
+prevents testing with multiple devices. The TEST_CASE_DEV_ARRAY resolves this by
+enabling multiple device configurations per test. Bcache tests need at
+least three devices, which can be specified in your configuration as follows:
+
+TEST_CASE_DEV_ARRAY[bcache/*]="/dev/nvme0n1 /dev/vdb /dev/vdc"
+
 ### Normal user
 
 To run test cases which require normal user privilege, prepare a user and

-- 
2.53.0

Re: [PATCH blktests v4 1/3] bcache: add bcache/001

[Shinichiro Kawasaki]

Thanks. I ran this test case and it passes in my environment. Good.

Please find my comments in line. Most of them are nit ones, and I do no
care them much. Just wanted to hear your opinion about my comment on partprobe.

On Feb 12, 2026 / 16:23, Daniel Wagner wrote:
[...]
> diff --git a/tests/bcache/001 b/tests/bcache/001
> new file mode 100755
> index 000000000000..7258d87566cb
> --- /dev/null
> +++ b/tests/bcache/001
[...]
> +test_device_array() {
> +	echo "Running ${TEST_NAME}"
> +
> +	if [[ ${#TEST_DEV_ARRAY[@]} -lt 3 ]]; then
> +		SKIP_REASONS+=("requires at least 3 devices")
> +		return 1
> +	fi
> +
> +	_setup_bcache "${TEST_DEV_ARRAY[@]}"
> +
> +	local bcache_nodes

Nit: I think "local -a bcache_nodes" is the better.

[...]

> diff --git a/tests/bcache/rc b/tests/bcache/rc
> new file mode 100644
> index 000000000000..cfd4094c2fe0
> --- /dev/null
> +++ b/tests/bcache/rc
> @@ -0,0 +1,375 @@
> +#!/bin/bash
> +# SPDX-License-Identifier: GPL-3.0+
> +# Copyright (C) 2026 Daniel Wagner, SUSE Labs
> +
> +. common/rc
> +
> +declare BCACHE_DEVS_LIST
> +
> +BCACHE_MAX_RETRIES=5
> +
> +group_requires() {
> +	_have_kernel_options MD BCACHE BCACHE_DEBUG AUTOFS_FS
> +	_have_program make-bcache
> +	_have_crypto_algorithm crc32c
> +}
> +
> +_bcache_wipe_devs() {
> +	local devs=("$@")
> +	local dev
> +
> +	for dev in "${devs[@]}"; do
> +		# Attempt a clean wipe first
> +		if wipefs --all --quiet "${dev}" 2>/dev/null; then
> +			continue
> +		fi
> +
> +		# Overwrite the first 10MB to clear stubborn partition tables or metadata
> +		if ! dd if=/dev/zero of="${dev}" bs=1M count=10 conv=notrunc status=none; then
> +			echo "Error: dd failed on ${dev}" >&2
> +		fi
> +
> +		# Wipe the Tail (Last 5MB)
> +		# bcache often places backup superblocks at the end of the device.
> +		local dev_size_mb
> +		dev_size_mb=$(blockdev --getsize64 "$dev" | awk '{print int($1 / 1024 / 1024)}')
> +
> +		if [ "$dev_size_mb" -gt 10 ]; then
> +			local seek_pos=$((dev_size_mb - 5))
> +			dd if=/dev/zero of="${dev}" bs=1M count=5 seek=$seek_pos conv=fsync status=none
> +		fi
> +
> +		# Refresh kernel partition table & wait for udev
> +		partprobe "$dev" 2>/dev/null

I think _have_program partprobe is required, or can we replace it with
"blockdev --rereadpt"?

> +		udevadm settle
> +
> +		# Try wiping again after clearing the headers
> +		if ! wipefs --all --quiet --force "${dev}"; then
> +			echo "Warning: Failed to wipe ${dev} even after dd." >&2
> +		fi
> +	done
> +}
> +
> +_bcache_register() {
> +	local devs=("$@")
> +	local dev timeout=0
> +
> +	while [[ ! -w /sys/fs/bcache/register ]] && (( timeout < 10 )); do
> +		sleep 1
> +		(( timeout ++ ))
> +	done
> +
> +	if [[ ! -w /sys/fs/bcache/register ]]; then
> +		echo "ERROR: bcache registration interface not found." >&2
> +		return 1
> +	fi
> +
> +	for dev in "${devs[@]}"; do
> +		local tmp_err
> +
> +		tmp_err="/tmp/bcache_reg_$$.err"
> +		if ! echo "${dev}" > /sys/fs/bcache/register 2> "${tmp_err}"; then
> +			local err_msg
> +
> +			err_msg=$(< "${tmp_err}")
> +			if [[ "${err_msg}" != *"Device or resource busy"* ]]; then
> +				echo "ERROR: Failed to register ${dev}: ${err_msg:-"Unknown error"}" >&2
> +			fi
> +		fi
> +		rm -f "${tmp_err}"
> +	done
> +}
> +
> +_create_bcache() {
> +	local -a cdevs=()
> +	local -a bdevs=()
> +	local -a ARGS=()
> +	local -a created_devs=()
> +	local bucket_size="64k"
> +	local block_size="4k"

Nit: I think "local dev" can be added here.

> +
> +	while [[ $# -gt 0 ]]; do
> +		case $1 in
> +			--cache)
> +				shift
> +				# Collect arguments until the next flag or end of input
> +				while [[ $# -gt 0 && ! $1 =~ ^-- ]]; do
> +					cdevs+=("$1")
> +					shift
> +				done
> +				;;
> +			--bdev)
> +				shift
> +				# Collect arguments until the next flag or end of input
> +				while [[ $# -gt 0 && ! $1 =~ ^-- ]]; do
> +					bdevs+=("$1")
> +					shift
> +				done
> +				;;
> +			--bucket-size)
> +				bucket_size="$2"
> +				shift 2
> +				;;
> +			--block-size)
> +				block_size="$2"
> +				shift 2
> +				;;
> +			--writeback)
> +				ARGS+=(--writeback)
> +				shift 1
> +				;;
> +			--discard)
> +				ARGS+=(--discard)
> +				shift 1
> +				;;
> +			*)
> +				echo "WARNING: unknown argument: $1"
> +				shift
> +				;;
> +		esac
> +	done
> +
> +	# add /dev prefix to device names
> +	cdevs=( "${cdevs[@]/#/\/dev\/}" )
> +	bdevs=( "${bdevs[@]/#/\/dev\/}" )
> +
> +	# make-bcache expects empty/cleared devices
> +	_bcache_wipe_devs "${cdevs[@]}" "${bdevs[@]}"
> +
> +	local -a cmd
> +	cmd=(make-bcache --wipe-bcache \
> +			--bucket "${bucket_size}" \
> +			--block "${block_size}")
> +	for dev in "${cdevs[@]}"; do cmd+=("--cache" "${dev}"); done
> +	for dev in "${bdevs[@]}"; do cmd+=("--bdev" "${dev}"); done
> +	cmd+=("${ARGS[@]}")
> +
> +	local output rc
> +	output=$("${cmd[@]}" 2>&1)
> +	rc="$?"
> +	if [[ "${rc}" -ne 0 ]]; then
> +		echo "ERROR: make-bcache failed:" >&2
> +		echo "$output" >&2
> +		return 1
> +	fi
> +
> +	local cset_uuid
> +	cset_uuid=$(echo "$output" | awk '/Set UUID:/ {print $3}' | head -n 1)
> +	if [[ -z "${cset_uuid}" ]]; then
> +		echo "ERROR: Could not extract cset UUID from make-bcache output" >&2
> +		return 1
> +	fi
> +
> +	local -a bdev_uuids
> +	mapfile -t bdev_uuids < <(echo "$output" | awk '
> +	  $1 == "UUID:" { last_uuid = $2 }
> +	  $1 == "version:" && $2 == "1" { print last_uuid}
> +	')
> +
> +	_bcache_register "${cdevs[@]}" "${bdevs[@]}"
> +	udevadm settle
> +
> +	for uuid in "${bdev_uuids[@]}"; do
> +		local link found
> +
> +		link=/dev/bcache/by-uuid/"${uuid}"
> +		found=false
> +
> +		for ((i=0; i<BCACHE_MAX_RETRIES; i++)); do
> +			if [[ -L "${link}" ]]; then
> +				created_devs+=("$(readlink -f "${link}")")
> +				found=true
> +				break
> +			fi
> +
> +			# poke udev to create the links
> +			udevadm trigger "block/$(basename "$(readlink -f "${link}" 2>/dev/null || echo "notfound")")" 2>/dev/null
> +			sleep 1
> +		done
> +
> +		if [[ "${found}" == "false" ]]; then
> +			echo "WARNING: Could not find device node for UUID ${uuid} after ${BCACHE_MAX_RETRIES}s" >&2
> +		fi
> +	done
> +
> +	printf "%s\n" "${created_devs[@]}"
> +}
> +
> +_remove_bcache() {
> +	local -a cdevs=()
> +	local -a bdevs=()
> +	local -a csets=()
> +	local -a bcache_devs=()
> +	local uuid
> +
> +	while [[ $# -gt 0 ]]; do
> +		case $1 in
> +			--cache)
> +				shift
> +				# Collect arguments until the next flag or end of input
> +				while [[ $# -gt 0 && ! $1 =~ ^-- ]]; do
> +					cdevs+=("$1")
> +					shift
> +				done
> +				;;
> +			--bdev)
> +				shift
> +				# Collect arguments until the next flag or end of input
> +				while [[ $# -gt 0 && ! $1 =~ ^-- ]]; do
> +					bdevs+=("$1")
> +					shift
> +				done
> +				;;
> +			--bcache)
> +				shift
> +				# Collect arguments until the next flag or end of input
> +				while [[ $# -gt 0 && ! $1 =~ ^-- ]]; do
> +					bcache_devs+=("$1")
> +					shift
> +				done
> +				;;
> +			*)
> +				echo "WARNING: unknown argument: $1"
> +				shift
> +				;;
> +		esac
> +	done
> +
> +	for dev in "${bcache_devs[@]}"; do
> +		local bcache bcache_dir
> +
> +		if mountpoint -q "${dev}" 2>/dev/null; then
> +			umount -l "${dev}"

Nit: The -q and -l options can be replaced with longer one for readability,
     --quiet and --lazy.

> +		fi
> +
> +		bcache="${dev##*/}"
> +		bcache_dir=/sys/block/"${bcache}"/bcache
> +		if [ -f "${bcache_dir}"/stop ]; then
> +			echo 1 > "${bcache_dir}"/stop
> +		fi
> +	done
> +
> +	# The cache could be detached, thus go through all caches and
> +	# look for the cdev in there.
> +	local cset_path
> +	for cset_path in /sys/fs/bcache/*-*-*-*-*; do
> +		local cache_link match_found
> +
> +		match_found=false
> +		for cache_link in "${cset_path}"/cache[0-9]*; do
> +			local full_sys_path _cdev cdev
> +
> +			full_sys_path="$(readlink -f "$cache_link")"
> +			_cdev="$(basename "${full_sys_path%/bcache}")"
> +
> +			for cdev in "${cdevs[@]}"; do
> +				if [ "${_cdev}" == "$(basename "${cdev}")"  ]; then
> +					match_found=true
> +					break 2
> +				fi
> +			done
> +		done
> +
> +		if [ "${match_found}" = false ]; then
> +			continue
> +		fi
> +
> +		cset="$(basename "${cset_path}")"
> +		if [ -d /sys/fs/bcache/"${cset}" ]; then
> +			echo 1 > /sys/fs/bcache/"${cset}"/unregister
> +			csets+=("${cset}")
> +		fi
> +	done
> +
> +	udevadm settle
> +
> +	local timeout
> +	for cset in "${csets[@]}"; do
> +		timeout=0
> +		while [[ -d /sys/fs/bcache/"${cset}" ]] && (( timeout < 10 )); do
> +			sleep 0.5
> +			(( timeout++ ))
> +		done
> +	done
> +
> +	_bcache_wipe_devs "${cdevs[@]}" "${bdevs[@]}"
> +}
> +
> +_cleanup_bcache() {
> +	local cset dev bcache bcache_devs cset_path

Nit: I think 'bdev' can be added in the list above.

> +	local -a csets=()
> +
> +	read -r -a bcache_devs <<< "${BCACHE_DEVS_LIST:-}"
> +
> +	# Don't let successive Ctrl-Cs interrupt the cleanup processes
> +	trap '' SIGINT
> +
> +	shopt -s nullglob
> +	for bcache  in /sys/block/bcache* ; do
> +		[ -e "${bcache}" ] || continue
> +
> +		if [[ -f "${bcache}/bcache/backing_dev_name" ]]; then
> +			bdev=$(basename "$(cat "${bcache}/bcache/backing_dev_name")")
> +
> +			for dev in "${bcache_devs[@]}"; do
> +				if [[ "${bdev}" == "$(basename "${dev}")" ]]; then
> +					echo "WARNING: Stopping bcache device ${bdev}"
> +					echo 1 > /sys/block/"${bdev}"/bcache/stop 2>/dev/null
> +					break
> +				fi
> +			done
> +		fi
> +	done
> +
> +	for cset_path in /sys/fs/bcache/*-*-*-*-*; do
> +		local cache_link match_found
> +
> +		match_found=false
> +		for cache_link in "${cset_path}"/cache[0-9]*; do
> +			local full_sys_path cdev
> +
> +			full_sys_path="$(readlink -f "$cache_link")"
> +			cdev="$(basename "${full_sys_path%/bcache}")"
> +
> +			for dev in "${bcache_devs[@]}"; do
> +				if [ "${cdev}" == "$(basename "${dev}")" ]; then
> +					match_found=true
> +					break 2
> +				fi
> +			done
> +		done
> +
> +		if [ "${match_found}" = false ]; then
> +			continue
> +		fi
> +
> +		cset="$(basename "${cset_path}")"
> +		if [ -d /sys/fs/bcache/"${cset}" ]; then
> +			echo "WARNING: Unregistering cset $(basename "${cset}")"
> +			echo 1 > /sys/fs/bcache/"${cset}"/unregister
> +			csets+=("${cset}")
> +		fi
> +	done
> +	shopt -u nullglob
> +
> +	udevadm settle
> +
> +	local timeout
> +	for cset in "${csets[@]}"; do
> +		timeout=0
> +		while [[ -d /sys/fs/bcache/"${cset}" ]] && (( timeout < 10 )); do
> +			sleep 0.5
> +			(( timeout++ ))
> +		done
> +	done
> +
> +	_bcache_wipe_devs "${bcache_devs[@]}"
> +
> +	trap SIGINT
> +}
> +
> +_setup_bcache() {
> +	BCACHE_DEVS_LIST="$*"
> +
> +	_register_test_cleanup _cleanup_bcache
> +}
> 
> -- 
> 2.53.0
> 

Re: [PATCH blktests v4 2/3] bcache: add bcache/002

[Shinichiro Kawasaki]

On Feb 12, 2026 / 16:23, Daniel Wagner wrote:
> Add test case from Stephen Zhang [1].
> 
> [1] https://lore.kernel.org/linux-bcache/CANubcdX7eNbH_bo4-f94DUbdiEbt04Vxy1MPyhm+CZyXB01FuQ@mail.gmail.com/
> 
> Signed-off-by: Daniel Wagner <dwagner@suse.de>

Thank you for adding this patch. When I ran this test case in my test
environment using the kernel v6.19, it failed:

    runtime  7.536s  ...  7.214s
    --- tests/bcache/002.out    2026-02-14 21:16:20.918000000 +0900
    +++ /home/shin/Blktests/blktests/results/nvme0n1_nvme2n1_nvme3n1_nvme4n1/bcache/002.out.bad 2026-02-16 14:29:25.596000000 +0900
    @@ -1,2 +1,3 @@
     Running bcache/002
     Device state: no cache
    +ERROR: Accounting leak detected!

Is this failure expected?

And let me leave a few nit comments in line.

> ---
>  tests/bcache/002     | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  tests/bcache/002.out |  2 ++
>  2 files changed, 64 insertions(+)
> 
> diff --git a/tests/bcache/002 b/tests/bcache/002
> new file mode 100755
> index 000000000000..c27178a90c2d
> --- /dev/null
> +++ b/tests/bcache/002
[...]
> +test_device_array() {
> +	echo "Running ${TEST_NAME}"
> +
> +	if [[ ${#TEST_DEV_ARRAY[@]} -lt 2 ]]; then
> +		SKIP_REASONS+=("requires at least 2 devices")
> +		return 1
> +	fi
> +
> +	_setup_bcache "${TEST_DEV_ARRAY[@]}"
> +
> +	local bcache_nodes bcache_dev bdev_name fio_pid

Nit: I think bcache_nodes should be declared as an array, with -a option.
     Also, 'state' can be added to this local var list.

> +
> +	mapfile -t bcache_nodes < <(_create_bcache \
> +				--cache "${TEST_DEV_ARRAY[0]##*/}" \
> +				--bdev "${TEST_DEV_ARRAY[1]##*/}" \
> +				--writeback)
> +
> +	bcache_dev="${bcache_nodes[0]}"
> +	bdev_name="$(basename "${bcache_dev}")"
> +	echo 1 > /sys/block/"${bdev_name}"/bcache/detach
> +
> +	state="$(cat /sys/block/"${bdev_name}"/bcache/state)"
> +	echo "Device state: ${state}"
> +
> +	_run_fio_rand_io --filename="${bcache_dev}" --time_base \
> +			--runtime=30 >> "$FULL" 2>&1 &
> +	fio_pid=$!
> +
> +	sleep 5
> +
> +	local stats_line util
> +	stats_line=$(iostat -x 1 2 "${bdev_name}" | grep -w "${bdev_name}" | tail -n 1)
> +	util="$(echo "${stats_line}" | awk '{print $NF}')"
> +
> +	if (( $(echo "${util} > 1.0" | bc -l) )); then

Nit: bc -l option can be --mathlib for readability.

> +		echo "ERROR: Accounting leak detected!"
> +	fi
> +
> +	{ pkill -f "fio.*${bcache_dev}"; wait "${fio_pid}"; } &> /dev/null

Nit: pkill -f option can be --full for readability.

> +
> +	_remove_bcache --bcache "${bcache_nodes[@]}" \
> +			--cache "${TEST_DEV_ARRAY[0]##*/}" \
> +			--bdev "${TEST_DEV_ARRAY[1]##*/}"
> +}

Re: [PATCH blktests v4 0/3] bcache: add initial test cases

[Daniel Wagner]

On Thu, Feb 12, 2026 at 04:23:30PM +0100, Daniel Wagner wrote:
> I've updated the v3 version with the feedback from Shinichiro for v2.
> Shinichiro, please note I did rewrite some of the logic in v3, thus some of your
> comments didn't apply. But hopefully I don't made a big mess :)

ping

Re: [PATCH blktests v4 0/3] bcache: add initial test cases

[Shinichiro Kawasaki]

On Mar 02, 2026 / 14:54, Daniel Wagner wrote:
> On Thu, Feb 12, 2026 at 04:23:30PM +0100, Daniel Wagner wrote:
> > I've updated the v3 version with the feedback from Shinichiro for v2.
> > Shinichiro, please note I did rewrite some of the logic in v3, thus some of your
> > comments didn't apply. But hopefully I don't made a big mess :)
> 
> ping

Daniel, I wonder if my replies [1][2] reached your mail box.

[1] https://lore.kernel.org/linux-block/aZQZkjEUw9VnVauX@shinmob/
[2] https://lore.kernel.org/linux-block/aZQcH-d-ZcgtMoJb@shinmob/

Today, I tried this patch series again on v7.0-rc2 kernel with the
TEST_CASE_DEV_ARRAY below:

  TEST_CASE_DEV_ARRAY[bcache/*]="/dev/nvme0n1 /dev/nvme1n1 /dev/nvme2n1 /dev/nvme4n1"

And found that new files named "nvme?n1" are created in the current directory.
Do you see the files created in your environment?

Also I saw the failure with the message "ERROR: Accounting leak detected!" as I
noted in [2].

Re: [PATCH blktests v4 0/3] bcache: add initial test cases

[Daniel Wagner]

Hi Shinichiro,

On Tue, Mar 03, 2026 at 12:57:18AM +0000, Shinichiro Kawasaki wrote:
> On Mar 02, 2026 / 14:54, Daniel Wagner wrote:
> > On Thu, Feb 12, 2026 at 04:23:30PM +0100, Daniel Wagner wrote:
> > > I've updated the v3 version with the feedback from Shinichiro for v2.
> > > Shinichiro, please note I did rewrite some of the logic in v3, thus some of your
> > > comments didn't apply. But hopefully I don't made a big mess :)
> > 
> > ping
> 
> Daniel, I wonder if my replies [1][2] reached your mail box.

Sorry, no, they didn't. Yet another hickup with our mail server...

> [1] https://lore.kernel.org/linux-block/aZQZkjEUw9VnVauX@shinmob/
> [2] https://lore.kernel.org/linux-block/aZQcH-d-ZcgtMoJb@shinmob/

I'll work on this then.

> Today, I tried this patch series again on v7.0-rc2 kernel with the
> TEST_CASE_DEV_ARRAY below:
> 
>   TEST_CASE_DEV_ARRAY[bcache/*]="/dev/nvme0n1 /dev/nvme1n1 /dev/nvme2n1 /dev/nvme4n1"
> 
> And found that new files named "nvme?n1" are created in the current directory.
> Do you see the files created in your environment?

Will check.

> Also I saw the failure with the message "ERROR: Accounting leak detected!" as I
> noted in [2].

I am not really sure if this test case should go in the current form.
I've just used Stephen's test case as input for figuring out what kind
of API is useful. I also see the leak error with v7.0-rc1 which has
3ef825dfd4e4 ("bcache: use bio cloning for detached device requests").
I might have done something wrong here.

BTW, iostat could be replaced by reading directly from sysfs,
e.g. /sys/block/nvme0n1/stat

Thanks,
Daniel

Re: [PATCH blktests v4 0/3] bcache: add initial test cases

[Stephen Zhang]

Daniel Wagner <dwagner@suse.de> 于2026年3月3日周二 16:04写道：
>
> Hi Shinichiro,
>
> On Tue, Mar 03, 2026 at 12:57:18AM +0000, Shinichiro Kawasaki wrote:
> > On Mar 02, 2026 / 14:54, Daniel Wagner wrote:
> > > On Thu, Feb 12, 2026 at 04:23:30PM +0100, Daniel Wagner wrote:
> > > > I've updated the v3 version with the feedback from Shinichiro for v2.
> > > > Shinichiro, please note I did rewrite some of the logic in v3, thus some of your
> > > > comments didn't apply. But hopefully I don't made a big mess :)
> > >
> > > ping
> >
> > Daniel, I wonder if my replies [1][2] reached your mail box.
>
> Sorry, no, they didn't. Yet another hickup with our mail server...
>
> > [1] https://lore.kernel.org/linux-block/aZQZkjEUw9VnVauX@shinmob/
> > [2] https://lore.kernel.org/linux-block/aZQcH-d-ZcgtMoJb@shinmob/
>
> I'll work on this then.
>
> > Today, I tried this patch series again on v7.0-rc2 kernel with the
> > TEST_CASE_DEV_ARRAY below:
> >
> >   TEST_CASE_DEV_ARRAY[bcache/*]="/dev/nvme0n1 /dev/nvme1n1 /dev/nvme2n1 /dev/nvme4n1"
> >
> > And found that new files named "nvme?n1" are created in the current directory.
> > Do you see the files created in your environment?
>
> Will check.
>
> > Also I saw the failure with the message "ERROR: Accounting leak detected!" as I
> > noted in [2].
>
> I am not really sure if this test case should go in the current form.
> I've just used Stephen's test case as input for figuring out what kind
> of API is useful. I also see the leak error with v7.0-rc1 which has
> 3ef825dfd4e4 ("bcache: use bio cloning for detached device requests").
> I might have done something wrong here.
>

Hi,
I noticed an issue with the test. The 100% utilization shown by iostat
during active I/O is NORMAL! The test is flawed - it's checking
utilization while fio is still running.
The test does:
1. Start fio in background with --runtime=30
2. Sleep only 5 seconds
3. Check iostat immediately (while fio is still active!)
A real leak would show persistent utilization AFTER all I/O completes.
During active I/O, 100% utilization is expected behavior.
To properly detect a leak, the test should:
1. Wait for fio to complete (wait $fio_pid)
2. Wait a few seconds for I/O to drain
3. Then check iostat
If utilization is still > 0% after I/O completes, then there's a real
accounting leak.

Thanks,
Shida


> BTW, iostat could be replaced by reading directly from sysfs,
> e.g. /sys/block/nvme0n1/stat
>
> Thanks,
> Daniel