[LTP] [PATCH v6 6/6] syscalls/statx11: Add basic test for STATX_DIOALIGN on block device

[Yang Xu]

Since STATX_DIOLAIGN is only supported on regular file and block device,
so this case is used to test the latter.

This test is tightly coupled to the kernel's current DIO restrictions on block
devices.  These changed in v6.0, and they are subject to further change in the
future.

It is fine for now because STATX_DIOALIGN is only in v6.1 and later
anyway.

Signed-off-by: Yang Xu <xuyang2018.jy@fujitsu.com>
---
 runtest/syscalls                           |  1 +
 testcases/kernel/syscalls/statx/.gitignore |  1 +
 testcases/kernel/syscalls/statx/statx11.c  | 89 ++++++++++++++++++++++
 3 files changed, 91 insertions(+)
 create mode 100644 testcases/kernel/syscalls/statx/statx11.c

diff --git a/runtest/syscalls b/runtest/syscalls
index e2548dae5..e5ad2c2f9 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -1766,6 +1766,7 @@ statx07 statx07
 statx08 statx08
 statx09 statx09
 statx10 statx10
+statx11 statx11
 
 membarrier01 membarrier01
 
diff --git a/testcases/kernel/syscalls/statx/.gitignore b/testcases/kernel/syscalls/statx/.gitignore
index 67341ff2d..48ac4078b 100644
--- a/testcases/kernel/syscalls/statx/.gitignore
+++ b/testcases/kernel/syscalls/statx/.gitignore
@@ -8,3 +8,4 @@
 /statx08
 /statx09
 /statx10
+/statx11
diff --git a/testcases/kernel/syscalls/statx/statx11.c b/testcases/kernel/syscalls/statx/statx11.c
new file mode 100644
index 000000000..653050855
--- /dev/null
+++ b/testcases/kernel/syscalls/statx/statx11.c
@@ -0,0 +1,89 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2023 FUJITSU LIMITED. All rights reserved.
+ * Author: Yang Xu <xuyang2018.jy@fujitsu.com>
+ */
+
+/*\
+ * [Description]
+ *
+ * It is a basic test for STATX_DIOALIGN mask on block device.
+ *
+ * - STATX_DIOALIGN   Want stx_dio_mem_align and stx_dio_offset_align value
+ *
+ * These two values are tightly coupled to the kernel's current DIO
+ * restrictions on block devices.
+ *
+ * Minimum Linux version required is v6.1.
+ */
+
+#define _GNU_SOURCE
+#include <sys/types.h>
+#include <sys/mount.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include "tst_test.h"
+#include "lapi/stat.h"
+
+static char sys_bdev_dma_path[1024], sys_bdev_logical_path[1024];
+
+static void verify_statx(void)
+{
+	struct statx buf;
+
+	TST_EXP_PASS_SILENT(statx(AT_FDCWD, tst_device->dev, 0, STATX_DIOALIGN, &buf),
+		"statx(AT_FDCWD, %s, 0, STATX_DIOALIGN, &buf)", tst_device->dev);
+
+	if (!(buf.stx_mask & STATX_DIOALIGN)) {
+		tst_res(TCONF, "Filesystem does not support STATX_DIOALIGN");
+		return;
+	}
+
+#ifdef HAVE_STRUCT_STATX_STX_DIO_MEM_ALIGN
+	/*
+	 * This test is tightly coupled to the kernel's current DIO restrictions
+	 * on block devices. The general rule of DIO needing to be aligned to the
+	 * block device's logical block size was relaxed to allow user buffers
+	 * (but not file offsets) aligned to the DMA alignment instead. See v6.0
+	 * commit bf8d08532bc1 ("iomap: add support for dma aligned direct-io") and
+	 * they are subject to further change in the future.
+	 * Also can see commit 2d985f8c6b9 ("vfs: support STATX_DIOALIGN on block devices).
+	 */
+	TST_ASSERT_ULONG(sys_bdev_dma_path, buf.stx_dio_mem_align - 1);
+	TST_ASSERT_ULONG(sys_bdev_logical_path, buf.stx_dio_offset_align);
+#else
+	tst_res(TCONF, "glibc statx struct miss stx_dio_mem_align field");
+#endif
+}
+
+static void setup(void)
+{
+	char full_name[256];
+	char *dev_name;
+
+	strcpy(full_name, tst_device->dev);
+	dev_name = SAFE_BASENAME(full_name);
+	sprintf(sys_bdev_logical_path, "/sys/block/%s/queue/logical_block_size", dev_name);
+
+	/*
+	 * Since /sys/block/%s/queue doesn't exist for partition, we need to
+	 * use a while to search block device instead of partition.
+	 */
+	while (access(sys_bdev_logical_path, F_OK) != 0) {
+		dev_name[strlen(dev_name)-1] = '\0';
+		sprintf(sys_bdev_logical_path, "/sys/block/%s/queue/logical_block_size", dev_name);
+	}
+
+	sprintf(sys_bdev_dma_path, "/sys/block/%s/queue/dma_alignment", dev_name);
+	if (access(sys_bdev_dma_path, F_OK) != 0)
+		tst_brk(TCONF, "dma_alignment sysfs file doesn't exist");
+}
+
+static struct tst_test test = {
+	.test_all = verify_statx,
+	.setup = setup,
+	.needs_device = 1,
+	.needs_root = 1,
+};
-- 
2.39.1