selftests: ublk: add kernel selftests for ublk

Both ublk driver and userspace heavily depends on io_uring subsystem,
and tools/testing/selftests/ should be the best place for holding this
cross-subsystem tests.

Add basic read/write IO test over this ublk null disk, and make sure ublk
working.

More tests will be added.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250228161919.2869102-2-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

MAINTAINERS

@@ -24237,6 +24237,7 @@ S:	Maintained
 F:	Documentation/block/ublk.rst
 F:	drivers/block/ublk_drv.c
 F:	include/uapi/linux/ublk_cmd.h
+F:	tools/testing/selftests/ublk/
 
 UBSAN
 M:	Kees Cook <kees@kernel.org>

tools/testing/selftests/Makefile

@@ -113,6 +113,7 @@ endif
 TARGETS += tmpfs
 TARGETS += tpm2
 TARGETS += tty
+TARGETS += ublk
 TARGETS += uevent
 TARGETS += user_events
 TARGETS += vDSO

tools/testing/selftests/ublk/.gitignore

@@ -0,0 +1,3 @@
+kublk
+/tools
+*-verify.state

tools/testing/selftests/ublk/Makefile

@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-2.0
+
+CFLAGS += -O3 -Wl,-no-as-needed -Wall -I $(top_srcdir)
+LDLIBS += -lpthread -lm -luring
+
+TEST_PROGS := test_null_01.sh
+
+TEST_GEN_PROGS_EXTENDED = kublk
+
+include ../lib.mk
+
+$(TEST_GEN_PROGS_EXTENDED): kublk.c null.c

tools/testing/selftests/ublk/config

@@ -0,0 +1 @@
+CONFIG_BLK_DEV_UBLK=m

tools/testing/selftests/ublk/kublk.h

@@ -0,0 +1,252 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef KUBLK_INTERNAL_H
+#define KUBLK_INTERNAL_H
+
+#include <unistd.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <stdio.h>
+#include <stdarg.h>
+#include <string.h>
+#include <pthread.h>
+#include <getopt.h>
+#include <limits.h>
+#include <poll.h>
+#include <sys/syscall.h>
+#include <sys/mman.h>
+#include <sys/ioctl.h>
+#include <sys/inotify.h>
+#include <sys/wait.h>
+#include <sys/eventfd.h>
+#include <liburing.h>
+#include <linux/ublk_cmd.h>
+
+#define __maybe_unused __attribute__((unused))
+#define MAX_BACK_FILES   4
+#ifndef min
+#define min(a, b) ((a) < (b) ? (a) : (b))
+#endif
+
+/****************** part 1: libublk ********************/
+
+#define CTRL_DEV		"/dev/ublk-control"
+#define UBLKC_DEV		"/dev/ublkc"
+#define UBLKB_DEV		"/dev/ublkb"
+#define UBLK_CTRL_RING_DEPTH            32
+#define ERROR_EVTFD_DEVID 	-2
+
+/* queue idle timeout */
+#define UBLKSRV_IO_IDLE_SECS		20
+
+#define UBLK_IO_MAX_BYTES               65536
+#define UBLK_MAX_QUEUES                 4
+#define UBLK_QUEUE_DEPTH                128
+
+#define UBLK_DBG_DEV            (1U << 0)
+#define UBLK_DBG_QUEUE          (1U << 1)
+#define UBLK_DBG_IO_CMD         (1U << 2)
+#define UBLK_DBG_IO             (1U << 3)
+#define UBLK_DBG_CTRL_CMD       (1U << 4)
+#define UBLK_LOG                (1U << 5)
+
+struct ublk_dev;
+struct ublk_queue;
+
+struct dev_ctx {
+	char tgt_type[16];
+	unsigned long flags;
+	unsigned nr_hw_queues;
+	unsigned queue_depth;
+	int dev_id;
+	int nr_files;
+	char *files[MAX_BACK_FILES];
+	unsigned int	logging:1;
+	unsigned int	all:1;
+
+	int _evtfd;
+};
+
+struct ublk_ctrl_cmd_data {
+	__u32 cmd_op;
+#define CTRL_CMD_HAS_DATA	1
+#define CTRL_CMD_HAS_BUF	2
+	__u32 flags;
+
+	__u64 data[2];
+	__u64 addr;
+	__u32 len;
+};
+
+struct ublk_io {
+	char *buf_addr;
+
+#define UBLKSRV_NEED_FETCH_RQ		(1UL << 0)
+#define UBLKSRV_NEED_COMMIT_RQ_COMP	(1UL << 1)
+#define UBLKSRV_IO_FREE			(1UL << 2)
+	unsigned short flags;
+	unsigned short refs;		/* used by target code only */
+
+	int result;
+};
+
+struct ublk_tgt_ops {
+	const char *name;
+	int (*init_tgt)(struct ublk_dev *);
+	void (*deinit_tgt)(struct ublk_dev *);
+
+	int (*queue_io)(struct ublk_queue *, int tag);
+	void (*tgt_io_done)(struct ublk_queue *,
+			int tag, const struct io_uring_cqe *);
+};
+
+struct ublk_tgt {
+	unsigned long dev_size;
+	unsigned int  sq_depth;
+	unsigned int  cq_depth;
+	const struct ublk_tgt_ops *ops;
+	struct ublk_params params;
+	char backing_file[1024 - 8 - sizeof(struct ublk_params)];
+};
+
+struct ublk_queue {
+	int q_id;
+	int q_depth;
+	unsigned int cmd_inflight;
+	unsigned int io_inflight;
+	struct ublk_dev *dev;
+	const struct ublk_tgt_ops *tgt_ops;
+	char *io_cmd_buf;
+	struct io_uring ring;
+	struct ublk_io ios[UBLK_QUEUE_DEPTH];
+#define UBLKSRV_QUEUE_STOPPING	(1U << 0)
+#define UBLKSRV_QUEUE_IDLE	(1U << 1)
+#define UBLKSRV_NO_BUF		(1U << 2)
+	unsigned state;
+	pid_t tid;
+	pthread_t thread;
+};
+
+struct ublk_dev {
+	struct ublk_tgt tgt;
+	struct ublksrv_ctrl_dev_info  dev_info;
+	struct ublk_queue q[UBLK_MAX_QUEUES];
+
+	int fds[2];	/* fds[0] points to /dev/ublkcN */
+	int nr_fds;
+	int ctrl_fd;
+	struct io_uring ring;
+};
+
+#ifndef offsetof
+#define offsetof(TYPE, MEMBER)  ((size_t)&((TYPE *)0)->MEMBER)
+#endif
+
+#ifndef container_of
+#define container_of(ptr, type, member) ({                              \
+	unsigned long __mptr = (unsigned long)(ptr);                    \
+	((type *)(__mptr - offsetof(type, member))); })
+#endif
+
+#define round_up(val, rnd) \
+	(((val) + ((rnd) - 1)) & ~((rnd) - 1))
+
+
+extern unsigned int ublk_dbg_mask;
+extern int ublk_queue_io_cmd(struct ublk_queue *q, struct ublk_io *io, unsigned tag);
+
+static inline int is_target_io(__u64 user_data)
+{
+	return (user_data & (1ULL << 63)) != 0;
+}
+
+static inline __u64 build_user_data(unsigned tag, unsigned op,
+		unsigned tgt_data, unsigned is_target_io)
+{
+	assert(!(tag >> 16) && !(op >> 8) && !(tgt_data >> 16));
+
+	return tag | (op << 16) | (tgt_data << 24) | (__u64)is_target_io << 63;
+}
+
+static inline unsigned int user_data_to_tag(__u64 user_data)
+{
+	return user_data & 0xffff;
+}
+
+static inline unsigned int user_data_to_op(__u64 user_data)
+{
+	return (user_data >> 16) & 0xff;
+}
+
+static inline void ublk_err(const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	vfprintf(stderr, fmt, ap);
+}
+
+static inline void ublk_log(const char *fmt, ...)
+{
+	if (ublk_dbg_mask & UBLK_LOG) {
+		va_list ap;
+
+		va_start(ap, fmt);
+		vfprintf(stdout, fmt, ap);
+	}
+}
+
+static inline void ublk_dbg(int level, const char *fmt, ...)
+{
+	if (level & ublk_dbg_mask) {
+		va_list ap;
+
+		va_start(ap, fmt);
+		vfprintf(stdout, fmt, ap);
+	}
+}
+
+static inline struct io_uring_sqe *ublk_queue_alloc_sqe(struct ublk_queue *q)
+{
+	unsigned left = io_uring_sq_space_left(&q->ring);
+
+	if (left < 1)
+		io_uring_submit(&q->ring);
+	return io_uring_get_sqe(&q->ring);
+}
+
+static inline void *ublk_get_sqe_cmd(const struct io_uring_sqe *sqe)
+{
+	return (void *)&sqe->cmd;
+}
+
+static inline void ublk_mark_io_done(struct ublk_io *io, int res)
+{
+	io->flags |= (UBLKSRV_NEED_COMMIT_RQ_COMP | UBLKSRV_IO_FREE);
+	io->result = res;
+}
+
+static inline const struct ublksrv_io_desc *ublk_get_iod(const struct ublk_queue *q, int tag)
+{
+	return (struct ublksrv_io_desc *)&(q->io_cmd_buf[tag * sizeof(struct ublksrv_io_desc)]);
+}
+
+static inline void ublk_set_sqe_cmd_op(struct io_uring_sqe *sqe, __u32 cmd_op)
+{
+	__u32 *addr = (__u32 *)&sqe->off;
+
+	addr[0] = cmd_op;
+	addr[1] = 0;
+}
+
+static inline int ublk_complete_io(struct ublk_queue *q, unsigned tag, int res)
+{
+	struct ublk_io *io = &q->ios[tag];
+
+	ublk_mark_io_done(io, res);
+
+	return ublk_queue_io_cmd(q, io, tag);
+}
+
+extern const struct ublk_tgt_ops null_tgt_ops;
+
+#endif

tools/testing/selftests/ublk/null.c

@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#include "kublk.h"
+
+static int ublk_null_tgt_init(struct ublk_dev *dev)
+{
+	const struct ublksrv_ctrl_dev_info *info = &dev->dev_info;
+	unsigned long dev_size = 250UL << 30;
+
+	dev->tgt.dev_size = dev_size;
+	dev->tgt.params = (struct ublk_params) {
+		.types = UBLK_PARAM_TYPE_BASIC,
+		.basic = {
+			.logical_bs_shift	= 9,
+			.physical_bs_shift	= 12,
+			.io_opt_shift		= 12,
+			.io_min_shift		= 9,
+			.max_sectors		= info->max_io_buf_bytes >> 9,
+			.dev_sectors		= dev_size >> 9,
+		},
+	};
+
+	return 0;
+}
+
+static int ublk_null_queue_io(struct ublk_queue *q, int tag)
+{
+	const struct ublksrv_io_desc *iod = ublk_get_iod(q, tag);
+
+	ublk_complete_io(q, tag, iod->nr_sectors << 9);
+	return 0;
+}
+
+const struct ublk_tgt_ops null_tgt_ops = {
+	.name = "null",
+	.init_tgt = ublk_null_tgt_init,
+	.queue_io = ublk_null_queue_io,
+};

tools/testing/selftests/ublk/test_common.sh

@@ -0,0 +1,58 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+_check_root() {
+	local ksft_skip=4
+
+	if [ $UID != 0 ]; then
+		echo please run this as root >&2
+		exit $ksft_skip
+	fi
+}
+
+_remove_ublk_devices() {
+	${UBLK_PROG} del -a
+}
+
+_get_ublk_dev_state() {
+	${UBLK_PROG} list -n "$1" | grep "state" | awk '{print $11}'
+}
+
+_get_ublk_daemon_pid() {
+	${UBLK_PROG} list -n "$1" | grep "pid" | awk '{print $7}'
+}
+
+_prep_test() {
+	_check_root
+	local type=$1
+	shift 1
+	echo "ublk $type: $@"
+}
+
+_show_result()
+{
+	if [ $2 -ne 0 ]; then
+		echo "$1 : [FAIL]"
+	else
+		echo "$1 : [PASS]"
+	fi
+}
+
+_cleanup_test() {
+	${UBLK_PROG} del -n $1
+}
+
+_add_ublk_dev() {
+	local kublk_temp=`mktemp /tmp/kublk-XXXXXX`
+	${UBLK_PROG} add $@ > ${kublk_temp} 2>&1
+	if [ $? -ne 0 ]; then
+		echo "fail to add ublk dev $@"
+		exit -1
+	fi
+	local dev_id=`grep "dev id" ${kublk_temp} | awk -F '[ :]' '{print $3}'`
+	udevadm settle
+	rm -f ${kublk_temp}
+	echo ${dev_id}
+}
+
+export UBLK_PROG=$(pwd)/kublk

tools/testing/selftests/ublk/test_null_01.sh

@@ -0,0 +1,19 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+. test_common.sh
+
+TID="null_01"
+ERR_CODE=0
+
+_prep_test "null" "basic IO test"
+
+dev_id=`_add_ublk_dev -t null`
+
+# run fio over the two disks
+fio --name=job1 --filename=/dev/ublkb${dev_id} --ioengine=libaio --rw=readwrite --iodepth=32 --size=256M > /dev/null 2>&1
+ERR_CODE=$?
+
+_cleanup_test ${dev_id} "null"
+
+_show_result $TID $ERR_CODE