On Wed, Jun 07, 2023 at 04:53:34PM +0200, Andreas Gruenbacher wrote:
> This is the same as generic/647, but with an additional test that writes
> a memory-mapped page onto itself using direct I/O.
>
> For direct I/O writes, the kernel will invalidate the page cache before
> and after carrying out the write. This puts filesystems that fault in
> pages on demand and then carry out the write with page faults disabled
> into a position in which they will not be able to make any progress.
>
> Signed-off-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
Looks good to me,
Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
--D
> ---
> src/mmap-rw-fault.c | 33 ++++++++++++++++++++++++++++++---
> tests/generic/728 | 42 ++++++++++++++++++++++++++++++++++++++++++
> tests/generic/728.out | 2 ++
> 3 files changed, 74 insertions(+), 3 deletions(-)
> create mode 100755 tests/generic/728
> create mode 100644 tests/generic/728.out
>
> diff --git a/src/mmap-rw-fault.c b/src/mmap-rw-fault.c
> index 82f9d978..161d9f79 100644
> --- a/src/mmap-rw-fault.c
> +++ b/src/mmap-rw-fault.c
> @@ -20,6 +20,7 @@
> #include <string.h>
> #include <errno.h>
> #include <err.h>
> +#include <getopt.h>
>
> char *filename;
> unsigned int page_size;
> @@ -109,11 +110,29 @@ static ssize_t do_write(int fd, const void *buf, size_t count, off_t offset)
> return count2;
> }
>
> +static void usage(const char *argv0)
> +{
> + fprintf(stderr, "Usage: %s [-2] {filename}\n", argv0);
> + exit(2);
> +}
> +
> int main(int argc, char *argv[])
> {
> - if (argc != 2)
> - errx(1, "no test filename argument given");
> - filename = argv[1];
> + int opt, opt_2 = 0;
> +
> + while ((opt = getopt(argc, argv, "2")) != -1) {
> + switch(opt) {
> + case '2':
> + opt_2 = 1;
> + break;
> + default:
> + usage(argv[0]);
> + }
> + }
> +
> + if (optind + 1 != argc)
> + usage(argv[0]);
> + filename = argv[optind];
>
> page_size = ret = sysconf(_SC_PAGE_SIZE);
> if (ret == -1)
> @@ -179,6 +198,14 @@ int main(int argc, char *argv[])
> errx(1, "pread (D_DIRECT) from hole is broken");
> done();
>
> + if (opt_2) {
> + init('f', O_RDWR | O_DIRECT);
> + ret = do_write(fd, addr + page_size, page_size, page_size);
> + if (ret != page_size)
> + err(1, "pwrite %s (O_DIRECT): %ld != %u", filename, ret, page_size);
> + done();
> + }
> +
> if (unlink(filename))
> err(1, "unlink %s", filename);
>
> diff --git a/tests/generic/728 b/tests/generic/728
> new file mode 100755
> index 00000000..483c7b73
> --- /dev/null
> +++ b/tests/generic/728
> @@ -0,0 +1,42 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2023 Red Hat, Inc. All Rights Reserved.
> +#
> +# FS QA Test 728
> +#
> +# Trigger page faults in the same file during read and write
> +#
> +# This is generic/647 with an additional test that writes a memory-mapped page
> +# onto itself using direct I/O.
> +#
> +# The kernel will invalidate the page cache before carrying out the write, so
> +# filesystems that fault in the page and then carry out the direct I/O write
> +# with page faults disabled will never make any progress.
> +#
> +. ./common/preamble
> +_begin_fstest auto quick
> +
> +# Override the default cleanup function.
> +_cleanup()
> +{
> + cd /
> + rm -f $tmp.*
> + rm -f $TEST_DIR/mmap-rw-fault.tmp
> +}
> +
> +# Import common functions.
> +. ./common/filter
> +
> +# real QA test starts here
> +
> +_supported_fs generic
> +_require_test
> +_require_odirect
> +_require_test_program mmap-rw-fault
> +
> +echo "Silence is golden"
> +
> +$here/src/mmap-rw-fault -2 $TEST_DIR/mmap-rw-fault.tmp
> +
> +status=$?
> +exit
> diff --git a/tests/generic/728.out b/tests/generic/728.out
> new file mode 100644
> index 00000000..ab39f45f
> --- /dev/null
> +++ b/tests/generic/728.out
> @@ -0,0 +1,2 @@
> +QA output created by 728
> +Silence is golden
> --
> 2.40.0
>
