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// 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 http://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.
*/
/*
* Tests async writeback behaviour. Creates a file, maps it into memory, and
* dirties every page within it. Then, calls ftruncate() to collapse the file
* back down to 0. This causes the kernel to begin writeback on the dirty
* pages so they can be freed, before it can complete the ftruncate() call.
* None of these are sync operations, so they should avoid the various "force
* flush" codepaths.
*/
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <stdlib.h>
#include <stdio.h>
#define _pdfail(f, l, s) \
do { perror("[" f "#" #l "] " s); exit(2); } while (0)
#define pdfail(str) _pdfail(__FILE__, __LINE__, str)
int
main(int argc, char **argv) {
if (argc != 3) {
printf("usage: mmap_ftruncate <file> <size>\n");
exit(2);
}
const char *file = argv[1];
char *end;
off_t sz = strtoull(argv[2], &end, 0);
if (end == argv[2] || *end != '\0' || sz == 0) {
fprintf(stderr, "E: invalid size");
exit(2);
}
int fd = open(file, O_CREAT|O_TRUNC|O_RDWR, S_IRUSR|S_IWUSR);
if (fd < 0)
pdfail("open");
if (ftruncate(fd, sz) < 0)
pdfail("ftruncate");
char *p = mmap(NULL, sz, PROT_WRITE, MAP_SHARED, fd, 0);
if (p == MAP_FAILED)
pdfail("mmap");
for (off_t off = 0; off < sz; off += 4096)
p[off] = 1;
if (ftruncate(fd, 0) < 0)
pdfail("ftruncate");
if (munmap(p, sz) < 0)
pdfail("munmap");
close(fd);
return (0);
}
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