[LTP] [RFC] [PATCH 1/2] io_uring: Test IORING READ and WRITE operations

[Sachin Sant <sachinp@linux.ibm.com>]

This test validates basic read and write operations using io_uring.
It tests:
 1. IORING_OP_WRITE - Writing data to a file
 2. IORING_OP_READ - Reading data from a file
 3. Data integrity verification

This patch also introduces a header file for common functions.

Signed-off-by: Sachin Sant <sachinp@linux.ibm.com>
---
 runtest/syscalls                              |   1 +
 testcases/kernel/syscalls/io_uring/.gitignore |   1 +
 .../kernel/syscalls/io_uring/io_uring03.c     | 145 +++++++++++
 .../syscalls/io_uring/io_uring_common.h       | 227 ++++++++++++++++++
 4 files changed, 374 insertions(+)
 create mode 100644 testcases/kernel/syscalls/io_uring/io_uring03.c
 create mode 100644 testcases/kernel/syscalls/io_uring/io_uring_common.h

diff --git a/runtest/syscalls b/runtest/syscalls
index 2179e007c..7dc80fe29 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -1898,6 +1898,7 @@ membarrier01 membarrier01
 
 io_uring01 io_uring01
 io_uring02 io_uring02
+io_uring03 io_uring03
 
 # Tests below may cause kernel memory leak
 perf_event_open03 perf_event_open03
diff --git a/testcases/kernel/syscalls/io_uring/.gitignore b/testcases/kernel/syscalls/io_uring/.gitignore
index 749db17db..9382ae413 100644
--- a/testcases/kernel/syscalls/io_uring/.gitignore
+++ b/testcases/kernel/syscalls/io_uring/.gitignore
@@ -1,2 +1,3 @@
 /io_uring01
 /io_uring02
+/io_uring03
diff --git a/testcases/kernel/syscalls/io_uring/io_uring03.c b/testcases/kernel/syscalls/io_uring/io_uring03.c
new file mode 100644
index 000000000..53d4feae5
--- /dev/null
+++ b/testcases/kernel/syscalls/io_uring/io_uring03.c
@@ -0,0 +1,145 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2026 IBM
+ * Author: Sachin Sant <sachinp@linux.ibm.com>
+ *
+ * Test IORING_OP_READ and IORING_OP_WRITE operations.
+ *
+ * This test validates basic read and write operations using io_uring.
+ * It tests:
+ * 1. IORING_OP_WRITE - Writing data to a file
+ * 2. IORING_OP_READ - Reading data from a file
+ * 3. Data integrity verification
+ */
+
+#include "io_uring_common.h"
+
+#define TEST_FILE "io_uring_test_file"
+#define QUEUE_DEPTH 2
+#define BLOCK_SZ 4096
+
+static char write_buf[BLOCK_SZ];
+static char read_buf[BLOCK_SZ];
+static struct io_uring_submit s;
+static sigset_t sig;
+
+static void test_write_read(void)
+{
+	int fd;
+	size_t i;
+
+	/* Prepare write buffer with pattern */
+	for (i = 0; i < BLOCK_SZ; i++)
+		write_buf[i] = 'A' + (i % 26);
+
+	/* Open file for writing */
+	fd = SAFE_OPEN(TEST_FILE, O_RDWR | O_CREAT | O_TRUNC, 0644);
+
+	/* Test IORING_OP_WRITE */
+	tst_res(TINFO, "Testing IORING_OP_WRITE");
+	io_uring_submit_sqe(&s, fd, IORING_OP_WRITE, write_buf, BLOCK_SZ, 0);
+
+	if (io_uring_wait_cqe(&s, BLOCK_SZ, IORING_OP_WRITE, &sig) == 0)
+		tst_res(TPASS, "IORING_OP_WRITE completed successfully");
+
+	/* Sync to ensure data is written */
+	SAFE_FSYNC(fd);
+
+	/* Test IORING_OP_READ */
+	tst_res(TINFO, "Testing IORING_OP_READ");
+	memset(read_buf, 0, BLOCK_SZ);
+	io_uring_submit_sqe(&s, fd, IORING_OP_READ, read_buf, BLOCK_SZ, 0);
+
+	if (io_uring_wait_cqe(&s, BLOCK_SZ, IORING_OP_READ, &sig) == 0)
+		tst_res(TPASS, "IORING_OP_READ completed successfully");
+
+	/* Verify data integrity */
+	if (memcmp(write_buf, read_buf, BLOCK_SZ) == 0) {
+		tst_res(TPASS, "Data integrity verified");
+	} else {
+		tst_res(TFAIL, "Data mismatch after read");
+		for (i = 0; i < BLOCK_SZ && i < 64; i++) {
+			if (write_buf[i] != read_buf[i]) {
+				tst_res(TINFO, "First mismatch at offset %zu: "
+					"wrote 0x%02x, read 0x%02x",
+					i, write_buf[i], read_buf[i]);
+				break;
+			}
+		}
+	}
+
+	SAFE_CLOSE(fd);
+}
+
+static void test_partial_io(void)
+{
+	int fd;
+	size_t half = BLOCK_SZ / 2;
+	size_t i;
+
+	tst_res(TINFO, "Testing partial I/O operations");
+
+	/* Prepare buffer */
+	for (i = 0; i < BLOCK_SZ; i++)
+		write_buf[i] = 'a' + (i % 26);
+
+	fd = SAFE_OPEN(TEST_FILE, O_RDWR | O_CREAT | O_TRUNC, 0644);
+
+	/* Write first half */
+	io_uring_submit_sqe(&s, fd, IORING_OP_WRITE, write_buf, half, 0);
+	if (io_uring_wait_cqe(&s, half, IORING_OP_WRITE, &sig) == 0)
+		tst_res(TPASS, "Partial write (first half) succeeded");
+
+	/* Write second half */
+	io_uring_submit_sqe(&s, fd, IORING_OP_WRITE, write_buf + half,
+			    half, half);
+	if (io_uring_wait_cqe(&s, half, IORING_OP_WRITE, &sig) == 0)
+		tst_res(TPASS, "Partial write (second half) succeeded");
+
+	SAFE_FSYNC(fd);
+
+	/* Read back in one operation */
+	memset(read_buf, 0, BLOCK_SZ);
+	io_uring_submit_sqe(&s, fd, IORING_OP_READ, read_buf, BLOCK_SZ, 0);
+	if (io_uring_wait_cqe(&s, BLOCK_SZ, IORING_OP_READ, &sig) == 0)
+		tst_res(TPASS, "Full read after partial writes succeeded");
+
+	/* Verify */
+	if (memcmp(write_buf, read_buf, BLOCK_SZ) == 0)
+		tst_res(TPASS, "Partial I/O data integrity verified");
+	else
+		tst_res(TFAIL, "Partial I/O data mismatch");
+
+	SAFE_CLOSE(fd);
+}
+
+static void run(void)
+{
+	io_uring_setup_queue(&s, QUEUE_DEPTH);
+	test_write_read();
+	test_partial_io();
+	io_uring_cleanup_queue(&s, QUEUE_DEPTH);
+}
+
+static void setup(void)
+{
+	io_uring_setup_supported_by_kernel();
+	sigemptyset(&sig);
+	memset(&s, 0, sizeof(s));
+}
+
+static struct tst_test test = {
+	.test_all = run,
+	.setup = setup,
+	.needs_tmpdir = 1,
+	.save_restore = (const struct tst_path_val[]) {
+		{"/proc/sys/kernel/io_uring_disabled", "0",
+			TST_SR_SKIP_MISSING | TST_SR_TCONF_RO},
+		{}
+	},
+	.tags = (const struct tst_tag[]) {
+		{"linux-git", "5d17b4a4b48c"},
+		{"linux-git", "2b188cc1bb85"},
+		{}
+	}
+};
diff --git a/testcases/kernel/syscalls/io_uring/io_uring_common.h b/testcases/kernel/syscalls/io_uring/io_uring_common.h
new file mode 100644
index 000000000..df05a0759
--- /dev/null
+++ b/testcases/kernel/syscalls/io_uring/io_uring_common.h
@@ -0,0 +1,227 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2026 IBM
+ * Author: Sachin Sant <sachinp@linux.ibm.com>
+ *
+ * Common definitions and helper functions for io_uring tests
+ */
+
+#ifndef IO_URING_COMMON_H
+#define IO_URING_COMMON_H
+
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+#include "config.h"
+#include "tst_test.h"
+#include "lapi/io_uring.h"
+
+/* Common structures for io_uring ring management */
+struct io_sq_ring {
+	unsigned int *head;
+	unsigned int *tail;
+	unsigned int *ring_mask;
+	unsigned int *ring_entries;
+	unsigned int *flags;
+	unsigned int *array;
+};
+
+struct io_cq_ring {
+	unsigned int *head;
+	unsigned int *tail;
+	unsigned int *ring_mask;
+	unsigned int *ring_entries;
+	struct io_uring_cqe *cqes;
+};
+
+struct io_uring_submit {
+	int ring_fd;
+	struct io_sq_ring sq_ring;
+	struct io_uring_sqe *sqes;
+	struct io_cq_ring cq_ring;
+	void *sq_ptr;
+	size_t sq_ptr_size;
+	void *cq_ptr;
+	size_t cq_ptr_size;
+};
+
+/*
+ * Setup io_uring instance with specified queue depth
+ * Returns 0 on success, -1 on failure
+ */
+static inline int io_uring_setup_queue(struct io_uring_submit *s,
+				       unsigned int queue_depth)
+{
+	struct io_sq_ring *sring = &s->sq_ring;
+	struct io_cq_ring *cring = &s->cq_ring;
+	struct io_uring_params p;
+
+	memset(&p, 0, sizeof(p));
+	s->ring_fd = io_uring_setup(queue_depth, &p);
+	if (s->ring_fd < 0) {
+		tst_brk(TBROK | TERRNO, "io_uring_setup() failed");
+		return -1;
+	}
+
+	s->sq_ptr_size = p.sq_off.array + p.sq_entries * sizeof(unsigned int);
+
+	/* Map submission queue ring buffer */
+	s->sq_ptr = SAFE_MMAP(0, s->sq_ptr_size, PROT_READ | PROT_WRITE,
+			      MAP_SHARED | MAP_POPULATE, s->ring_fd,
+			      IORING_OFF_SQ_RING);
+
+	/* Save submission queue pointers */
+	sring->head = s->sq_ptr + p.sq_off.head;
+	sring->tail = s->sq_ptr + p.sq_off.tail;
+	sring->ring_mask = s->sq_ptr + p.sq_off.ring_mask;
+	sring->ring_entries = s->sq_ptr + p.sq_off.ring_entries;
+	sring->flags = s->sq_ptr + p.sq_off.flags;
+	sring->array = s->sq_ptr + p.sq_off.array;
+
+	/* Map submission queue entries */
+	s->sqes = SAFE_MMAP(0, p.sq_entries * sizeof(struct io_uring_sqe),
+			    PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE,
+			    s->ring_fd, IORING_OFF_SQES);
+
+	s->cq_ptr_size = p.cq_off.cqes +
+			 p.cq_entries * sizeof(struct io_uring_cqe);
+
+	/* Map completion queue ring buffer */
+	s->cq_ptr = SAFE_MMAP(0, s->cq_ptr_size, PROT_READ | PROT_WRITE,
+			      MAP_SHARED | MAP_POPULATE, s->ring_fd,
+			      IORING_OFF_CQ_RING);
+
+	/* Save completion queue pointers */
+	cring->head = s->cq_ptr + p.cq_off.head;
+	cring->tail = s->cq_ptr + p.cq_off.tail;
+	cring->ring_mask = s->cq_ptr + p.cq_off.ring_mask;
+	cring->ring_entries = s->cq_ptr + p.cq_off.ring_entries;
+	cring->cqes = s->cq_ptr + p.cq_off.cqes;
+
+	return 0;
+}
+
+/*
+ * Cleanup io_uring instance and unmap all memory regions
+ */
+static inline void io_uring_cleanup_queue(struct io_uring_submit *s,
+					  unsigned int queue_depth)
+{
+	if (s->sqes)
+		SAFE_MUNMAP(s->sqes, queue_depth * sizeof(struct io_uring_sqe));
+	if (s->cq_ptr)
+		SAFE_MUNMAP(s->cq_ptr, s->cq_ptr_size);
+	if (s->sq_ptr)
+		SAFE_MUNMAP(s->sq_ptr, s->sq_ptr_size);
+	if (s->ring_fd > 0)
+		SAFE_CLOSE(s->ring_fd);
+}
+
+/*
+ * Submit a single SQE to the submission queue
+ * For basic read/write operations (non-vectored)
+ */
+static inline void io_uring_submit_sqe(struct io_uring_submit *s, int fd,
+				       int opcode, void *buf, size_t len,
+				       off_t offset)
+{
+	struct io_sq_ring *sring = &s->sq_ring;
+	unsigned int tail, index;
+	struct io_uring_sqe *sqe;
+
+	tail = *sring->tail;
+	index = tail & *sring->ring_mask;
+	sqe = &s->sqes[index];
+
+	memset(sqe, 0, sizeof(*sqe));
+	sqe->opcode = opcode;
+	sqe->fd = fd;
+	sqe->addr = (unsigned long)buf;
+	sqe->len = len;
+	sqe->off = offset;
+	sqe->user_data = opcode;
+
+	sring->array[index] = index;
+	tail++;
+
+	/* Update tail to make SQE visible to kernel */
+	*sring->tail = tail;
+}
+
+/*
+ * Submit a vectored SQE to the submission queue
+ * For readv/writev operations
+ */
+static inline void io_uring_submit_sqe_vec(struct io_uring_submit *s, int fd,
+					   int opcode, struct iovec *iovs,
+					   int nr_vecs, off_t offset)
+{
+	struct io_sq_ring *sring = &s->sq_ring;
+	unsigned int tail, index;
+	struct io_uring_sqe *sqe;
+
+	tail = *sring->tail;
+	index = tail & *sring->ring_mask;
+	sqe = &s->sqes[index];
+
+	memset(sqe, 0, sizeof(*sqe));
+	sqe->opcode = opcode;
+	sqe->fd = fd;
+	sqe->addr = (unsigned long)iovs;
+	sqe->len = nr_vecs;
+	sqe->off = offset;
+	sqe->user_data = opcode;
+
+	sring->array[index] = index;
+	tail++;
+
+	/* Update tail to make SQE visible to kernel */
+	*sring->tail = tail;
+}
+
+/*
+ * Wait for and validate a completion queue entry
+ * Returns 0 on success, -1 on failure
+ */
+static inline int io_uring_wait_cqe(struct io_uring_submit *s,
+				    int expected_res, int expected_opcode,
+				    sigset_t *sig)
+{
+	struct io_cq_ring *cring = &s->cq_ring;
+	struct io_uring_cqe *cqe;
+	unsigned int head;
+	int ret;
+
+	ret = io_uring_enter(s->ring_fd, 1, 1, IORING_ENTER_GETEVENTS, sig);
+	if (ret < 0) {
+		tst_res(TFAIL | TERRNO, "io_uring_enter() failed");
+		return -1;
+	}
+
+	head = *cring->head;
+	if (head == *cring->tail) {
+		tst_res(TFAIL, "No completion event received");
+		return -1;
+	}
+
+	cqe = &cring->cqes[head & *cring->ring_mask];
+
+	if (cqe->user_data != (uint64_t)expected_opcode) {
+		tst_res(TFAIL, "Unexpected user_data: got %llu, expected %d",
+			cqe->user_data, expected_opcode);
+		*cring->head = head + 1;
+		return -1;
+	}
+
+	if (cqe->res != expected_res) {
+		tst_res(TFAIL, "Operation failed: res=%d, expected=%d",
+			cqe->res, expected_res);
+		*cring->head = head + 1;
+		return -1;
+	}
+
+	*cring->head = head + 1;
+	return 0;
+}
+
+#endif /* IO_URING_COMMON_H */
-- 
2.39.1


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