1 files changed, 84 insertions, 0 deletions
diff --git a/sys/contrib/openzfs/tests/zfs-tests/cmd/mmap_write_sync.c b/sys/contrib/openzfs/tests/zfs-tests/cmd/mmap_write_sync.c
new file mode 100644
index 000000000000..ad5e37f24960
--- /dev/null
+++ b/sys/contrib/openzfs/tests/zfs-tests/cmd/mmap_write_sync.c
@@ -0,0 +1,84 @@
+// SPDX-License-Identifier: CDDL-1.0
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or https://opensource.org/licenses/CDDL-1.0.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+
+/*
+ * Copyright (c) 2025, Klara, Inc.
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+
+#define	PAGES	(8)
+
+int
+main(int argc, char **argv)
+{
+	if (argc != 2) {
+		fprintf(stderr, "usage: %s <filename>\n", argv[0]);
+		exit(1);
+	}
+
+	long page_size = sysconf(_SC_PAGESIZE);
+	if (page_size < 0) {
+		perror("sysconf");
+		exit(2);
+	}
+	size_t map_size = page_size * PAGES;
+
+	int fd = open(argv[1], O_CREAT|O_RDWR, S_IRWXU|S_IRWXG|S_IRWXO);
+	if (fd < 0) {
+		perror("open");
+		exit(2);
+	}
+
+	if (ftruncate(fd, map_size) < 0) {
+		perror("ftruncate");
+		close(fd);
+		exit(2);
+	}
+
+	uint64_t *p =
+	    mmap(NULL, map_size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
+	if (p == MAP_FAILED) {
+		perror("mmap");
+		close(fd);
+		exit(2);
+	}
+
+	for (int i = 0; i < (map_size / sizeof (uint64_t)); i++)
+		p[i] = 0x0123456789abcdef;
+
+	if (msync(p, map_size, MS_SYNC) < 0) {
+		perror("msync");
+		munmap(p, map_size);
+		close(fd);
+		exit(3);
+	}
+
+	munmap(p, map_size);
+	close(fd);
+	exit(0);
+}