Re: [PATCH] generic: test pagecache invalidation after direct write

Eryu Guan
2017-03-20T07:29:14Z

Hi,

On Mon, Mar 13, 2017 at 02:50:05PM +0800, Eryu Guan wrote:
> Test if direct write invalidates pagecache correctly, so that subsequent
> buffer read reads the correct data from disk.
>
> This test is inspired LTP tests dio29, and serves as a regression test
> for the bug found by it, see kernel commit c771c14baa33 ("iomap:
> invalidate page caches should be after iomap_dio_complete() in direct
> write").
>
> The test can be easily expanded to other write/read combinations, e.g.
> buffer write + direct read and direct write + direct read, so they are
> also being tested.
>
> Signed-off-by: Eryu Guan <eguan@redhat.com>

Need some reviews on this. Cc'd xfs list as this bug was originally
found in xfs testing.

Thanks,
Eryu

> ---
> .gitignore | 1 +
> src/Makefile | 3 +-
> src/dio-invalidate-cache.c | 335 +++++++++++++++++++++++++++++++++++++++++++++
> tests/generic/418 | 122 +++++++++++++++++
> tests/generic/418.out | 2 +
> tests/generic/group | 1 +
> 6 files changed, 463 insertions(+), 1 deletion(-)
> create mode 100644 src/dio-invalidate-cache.c
> create mode 100755 tests/generic/418
> create mode 100644 tests/generic/418.out
>
> diff --git a/.gitignore b/.gitignore
> index 48a40a0..1ed2a92 100644
> --- a/.gitignore
> +++ b/.gitignore
> @@ -45,6 +45,7 @@
> /src/dbtest
> /src/devzero
> /src/dio-interleaved
> +/src/dio-invalidate-cache
> /src/dirperf
> /src/dirstress
> /src/dmiperf
> diff --git a/src/Makefile b/src/Makefile
> index eb5a56c..a7f27f0 100644
> --- a/src/Makefile
> +++ b/src/Makefile
> @@ -21,7 +21,8 @@ LINUX_TARGETS = xfsctl bstat t_mtab getdevicesize preallo_rw_pattern_reader \
> stale_handle pwrite_mmap_blocked t_dir_offset2 seek_sanity_test \
> seek_copy_test t_readdir_1 t_readdir_2 fsync-tester nsexec cloner \
> renameat2 t_getcwd e4compact test-nextquota punch-alternating \
> - attr-list-by-handle-cursor-test listxattr dio-interleaved t_dir_type
> + attr-list-by-handle-cursor-test listxattr dio-interleaved t_dir_type \
> + dio-invalidate-cache
>
> SUBDIRS =
>
> diff --git a/src/dio-invalidate-cache.c b/src/dio-invalidate-cache.c
> new file mode 100644
> index 0000000..4fd72ab
> --- /dev/null
> +++ b/src/dio-invalidate-cache.c
> @@ -0,0 +1,335 @@
> +/*
> + * Copyright (c) 2017 Red Hat Inc. All Rights Reserved.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it would be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write the Free Software Foundation,
> + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
> + */
> +
> +/*
> + * Fork N children, each child writes to and reads from its own region of the
> + * same test file, and check if what it reads is what it writes. The test
> + * region is determined by N * blksz. Write and read operation can be either
> + * direct or buffered.
> + */
> +
> +#ifndef _GNU_SOURCE
> +#define _GNU_SOURCE
> +#endif
> +#include <sys/file.h>
> +#include <sys/types.h>
> +#include <sys/wait.h>
> +#include <errno.h>
> +#include <fcntl.h>
> +#include <signal.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <unistd.h>
> +
> +#define DEF_BLKSZ 4096
> +
> +int verbose = 0;
> +
> +static void usage(const char *prog)
> +{
> + fprintf(stderr, "Usage: %s [-Fhptrwv] [-b blksz] [-n nr_child] [-i iterations] [-o offset] <-f filename>\n", prog);
> + fprintf(stderr, "\t-F\tPreallocate all blocks by writing them before test\n");
> + fprintf(stderr, "\t-p\tPreallocate all blocks using fallocate(2) before test\n");
> + fprintf(stderr, "\t-t\tTruncate test file to largest size before test\n");
> + fprintf(stderr, "\t-r\tDo direct read\n");
> + fprintf(stderr, "\t-w\tDo direct write\n");
> + fprintf(stderr, "\t-v\tBe verbose\n");
> + fprintf(stderr, "\t-h\tshow this help message\n");
> + exit(EXIT_FAILURE);
> +}
> +
> +static int cmpbuf(char *b1, char *b2, int bsize)
> +{
> + int i;
> +
> + for (i = 0; i < bsize; i++) {
> + if (strncmp(&b1[i], &b2[i], 1)) {
> + fprintf(stderr, "cmpbuf: offset %d: Expected: 0x%x,"
> + " got 0x%x\n", i, b1[i], b2[i]);
> + return 1;
> + }
> + }
> + return 0;
> +}
> +
> +static void kill_children(pid_t *pids, int nr_child)
> +{
> + int i;
> + pid_t pid;
> +
> + for (i = 0; i < nr_child; i++) {
> + pid = *(pids + i);
> + if (pid == 0)
> + continue;
> + kill(pid, SIGTERM);
> + }
> + return;
> +}
> +
> +static int wait_children(pid_t *pids, int nr_child)
> +{
> + int i, status, ret = 0;
> + pid_t pid;
> +
> + for (i = 0; i < nr_child; i++) {
> + pid = *(pids + i);
> + if (pid == 0)
> + continue;
> + waitpid(pid, &status, 0);
> + ret += WEXITSTATUS(status);
> + }
> + return ret;
> +}
> +
> +static void dumpbuf(char *buf, int size, int blksz)
> +{
> + int i;
> +
> + printf("dumping buffer content\n");
> + for (i = 0; i < size; i++) {
> + if (((i % blksz) == 0) || ((i % 64) == 0))
> + putchar('\n');
> + fprintf(stderr, "%x", buf[i]);
> + }
> + putchar('\n');
> +}
> +
> +static int run_test(const char *filename, int n_child, int blksz, off_t offset,
> + int nr_iter, int flag_rd, int flag_wr)
> +{
> + char *buf_rd;
> + char *buf_wr;
> + off_t seekoff;
> + int fd_rd, fd_wr;
> + int i, ret;
> + long page_size;
> +
> + seekoff = offset + blksz * n_child;
> +
> + page_size = sysconf(_SC_PAGESIZE);
> + ret = posix_memalign((void **)&buf_rd, (size_t)page_size,
> + blksz > page_size ? blksz : (size_t)page_size);
> + if (ret) {
> + fprintf(stderr, "posix_memalign(buf_rd, %d, %d) failed: %d\n",
> + blksz, blksz, ret);
> + exit(EXIT_FAILURE);
> + }
> + memset(buf_rd, 0, blksz);
> + ret = posix_memalign((void **)&buf_wr, (size_t)page_size,
> + blksz > page_size ? blksz : (size_t)page_size);
> + if (ret) {
> + fprintf(stderr, "posix_memalign(buf_wr, %d, %d) failed: %d\n",
> + blksz, blksz, ret);
> + exit(EXIT_FAILURE);
> + }
> + memset(buf_wr, 0, blksz);
> +
> + fd_rd = open(filename, flag_rd);
> + if (fd_rd < 0) {
> + perror("open readonly for read");
> + exit(EXIT_FAILURE);
> + }
> +
> + fd_wr = open(filename, flag_wr);
> + if (fd_wr < 0) {
> + perror("open writeonly for direct write");
> + exit(EXIT_FAILURE);
> + }
> +
> +#define log(format, ...) \
> + if (verbose) { \
> + printf("[%d:%d] ", n_child, i); \
> + printf(format, __VA_ARGS__); \
> + }
> +
> +
> + /* seek, write, read and verify */
> + ret = 0;
> + for (i = 0; i < nr_iter; i++) {
> + memset(buf_wr, n_child + i + 1, blksz);
> + if (lseek(fd_wr, seekoff, SEEK_SET) < 0) {
> + perror("lseek for write");
> + exit(EXIT_FAILURE);
> + }
> + log("write(fd_wr, %p, %d)\n", buf_wr, blksz);
> + if (write(fd_wr, buf_wr, blksz) < 0) {
> + perror("direct write");
> + exit(EXIT_FAILURE);
> + }
> +
> + /* make sure buffer write hit disk before direct read */
> + if (!(flag_wr & O_DIRECT)) {
> + if (fsync(fd_wr) < 0) {
> + perror("fsync(fd_wr)");
> + exit(EXIT_FAILURE);
> + }
> + }
> +
> + if (lseek(fd_rd, seekoff, SEEK_SET) < 0) {
> + perror("lseek for read");
> + exit(EXIT_FAILURE);
> + }
> + log("read(fd_rd, %p, %d)\n", buf_rd, blksz);
> + if (read(fd_rd, buf_rd, blksz) != blksz) {
> + perror("buffer read");
> + exit(EXIT_FAILURE);
> + }
> + if (cmpbuf(buf_wr, buf_rd, blksz) != 0) {
> + fprintf(stderr, "[%d:%d] FAIL - comparsion failed, "
> + "offset %d\n", n_child, i, (int)seekoff);
> + ret += 1;
> + if (verbose)
> + dumpbuf(buf_rd, blksz, blksz);
> + exit(EXIT_FAILURE);
> + }
> + }
> + exit(ret);
> +}
> +
> +int main(int argc, char *argv[])
> +{
> + int nr_iter = 1;
> + int nr_child = 1;
> + int blksz = DEF_BLKSZ;
> + int fd, i, ret = 0;
> + int flag_rd = O_RDONLY;
> + int flag_wr = O_WRONLY;
> + int do_trunc = 0;
> + int pre_fill = 0;
> + int pre_alloc = 0;
> + pid_t pid;
> + pid_t *pids;
> + off_t offset = 0;
> + char *filename = NULL;
> +
> + while ((i = getopt(argc, argv, "b:i:n:f:Fpo:tvrw")) != -1) {
> + switch (i) {
> + case 'b':
> + if ((blksz = atoi(optarg)) <= 0) {
> + fprintf(stderr, "blksz must be > 0\n");
> + exit(EXIT_FAILURE);
> + }
> + if (blksz % 512 != 0) {
> + fprintf(stderr, "blksz must be multiple of 512\n");
> + exit(EXIT_FAILURE);
> + }
> + break;
> + case 'i':
> + if ((nr_iter = atoi(optarg)) <= 0) {
> + fprintf(stderr, "iterations must be > 0\n");
> + exit(EXIT_FAILURE);
> + }
> + break;
> + case 'n':
> + if ((nr_child = atoi(optarg)) <= 0) {
> + fprintf(stderr, "no of children must be > 0\n");
> + exit(EXIT_FAILURE);
> + }
> + break;
> + case 'f':
> + filename = optarg;
> + break;
> + case 'F':
> + pre_fill = 1;
> + break;
> + case 'p':
> + pre_alloc = 1;
> + break;
> + case 'r':
> + flag_rd |= O_DIRECT;
> + break;
> + case 'w':
> + flag_wr |= O_DIRECT;
> + break;
> + case 't':
> + do_trunc = 1;
> + break;
> + case 'o':
> + if ((offset = atol(optarg)) < 0) {
> + fprintf(stderr, "offset must be >= 0\n");
> + exit(EXIT_FAILURE);
> + }
> + break;
> + case 'v':
> + verbose = 1;
> + break;
> + case 'h': /* fall through */
> + default:
> + usage(argv[0]);
> + }
> + }
> +
> + if (filename == NULL)
> + usage(argv[0]);
> + if (pre_fill && pre_alloc) {
> + fprintf(stderr, "Error: -F and -p are both specified\n");
> + exit(EXIT_FAILURE);
> + }
> +
> + pids = malloc(nr_child * sizeof(pid_t));
> + if (!pids) {
> + fprintf(stderr, "failed to malloc memory for pids\n");
> + exit(EXIT_FAILURE);
> + }
> + memset(pids, 0, nr_child * sizeof(pid_t));
> +
> + /* create & truncate testfile first */
> + fd = open(filename, O_CREAT | O_TRUNC | O_RDWR, 0600);
> + if (fd < 0) {
> + perror("create & truncate testfile");
> + free(pids);
> + exit(EXIT_FAILURE);
> + }
> + if (do_trunc && (ftruncate(fd, blksz * nr_child) < 0)) {
> + perror("ftruncate failed");
> + free(pids);
> + exit(EXIT_FAILURE);
> + }
> + if (pre_fill) {
> + char *buf;
> + buf = malloc(blksz * nr_child);
> + memset(buf, 's', blksz * nr_child);
> + write(fd, buf, blksz * nr_child);
> + free(buf);
> + }
> + if (pre_alloc) {
> + fallocate(fd, 0, 0, blksz * nr_child);
> + }
> + close(fd);
> + sync();
> +
> + /* fork workers */
> + for (i = 0; i < nr_child; i++) {
> + pid = fork();
> + if (pid < 0) {
> + perror("fork");
> + kill_children(pids, nr_child);
> + free(pids);
> + exit(EXIT_FAILURE);
> + } else if (pid == 0) {
> + run_test(filename, i, blksz, offset, nr_iter,
> + flag_rd, flag_wr);
> + } else {
> + *(pids + i) = pid;
> + }
> + }
> +
> + ret = wait_children(pids, nr_child);
> + free(pids);
> + exit(ret);
> +}
> diff --git a/tests/generic/418 b/tests/generic/418
> new file mode 100755
> index 0000000..2d56cf0
> --- /dev/null
> +++ b/tests/generic/418
> @@ -0,0 +1,122 @@
> +#! /bin/bash
> +# FS QA Test 418
> +#
> +# Test pagecache invalidation in buffer/direct write/read combination.
> +#
> +# Fork N children, each child writes to and reads from its own region of the
> +# same test file, and check if what it reads is what it writes. The test region
> +# is determined by N * blksz. Write and read operation can be either direct or
> +# buffered.
> +#
> +# Regression test for commit c771c14baa33 ("iomap: invalidate page caches
> +# should be after iomap_dio_complete() in direct write")
> +#
> +#-----------------------------------------------------------------------
> +# Copyright (c) 2017 Red Hat Inc. All Rights Reserved.
> +#
> +# This program is free software; you can redistribute it and/or
> +# modify it under the terms of the GNU General Public License as
> +# published by the Free Software Foundation.
> +#
> +# This program is distributed in the hope that it would be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program; if not, write the Free Software Foundation,
> +# Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
> +#-----------------------------------------------------------------------
> +#
> +
> +seq=`basename $0`
> +seqres=$RESULT_DIR/$seq
> +echo "QA output created by $seq"
> +
> +here=`pwd`
> +tmp=/tmp/$$
> +status=1 # failure is the default!
> +trap "_cleanup; exit \$status" 0 1 2 3 15
> +
> +_cleanup()
> +{
> + cd /
> + rm -f $tmp.*
> +}
> +
> +# get standard environment, filters and checks
> +. ./common/rc
> +. ./common/filter
> +
> +# remove previous $seqres.full before test
> +rm -f $seqres.full
> +
> +# real QA test starts here
> +_supported_fs generic
> +_supported_os Linux
> +_require_test
> +_require_odirect
> +_require_block_device $TEST_DEV
> +_require_test_program "dio-invalidate-cache"
> +_require_test_program "feature"
> +
> +diotest=$here/src/dio-invalidate-cache
> +testfile=$TEST_DIR/$seq-diotest
> +sectorsize=`blockdev --getss $TEST_DEV`
> +pagesize=`src/feature -s`
> +
> +# test case array, test different write/read combinations
> +# -r: use direct read
> +# -w: use direct write
> +# -t: truncate file to final size before test, i.e. write to hole
> +# -p: fallocate whole file before test, i.e. write to allocated but unwritten extents
> +# -F: fulfill whole file before test, i.e. write to alloated & written extents
> +t_cases=(
> + "-w"
> + "-wt"
> + "-wp"
> + "-wF"
> + "-r"
> + "-rt"
> + "-rp"
> + "-rF"
> + "-rw"
> + "-rwt"
> + "-rwp"
> + "-rwF"
> +)
> +
> +runtest()
> +{
> + local i=0
> + local tc=""
> + local loop=$1
> + shift
> +
> + for tc in ${t_cases[*]}; do
> + echo "diotest $tc $*" >> $seqres.full
> + i=0
> + while [ $i -lt $loop ]; do
> + $diotest $tc $* -f $testfile
> + if [ $? -ne 0 ]; then
> + echo "diotest $tc $* failed at loop $i" | \
> + tee -a $seqres.full
> + break
> + fi
> + let i=i+1
> + done
> + done
> +}
> +
> +while [ $sectorsize -le $((pagesize * 2)) ]; do
> + # reproducer for the original bug
> + runtest $((10 * LOAD_FACTOR)) -b $sectorsize -n 3 -i 1
> + # try more processes and iterations
> + runtest $((5 * LOAD_FACTOR)) -b $sectorsize -n 8 -i 4
> + sectorsize=$((sectorsize * 2))
> +done
> +echo "Silence is golden"
> +
> +# success, all done
> +status=0
> +exit
> diff --git a/tests/generic/418.out b/tests/generic/418.out
> new file mode 100644
> index 0000000..954de31
> --- /dev/null
> +++ b/tests/generic/418.out
> @@ -0,0 +1,2 @@
> +QA output created by 418
> +Silence is golden
> diff --git a/tests/generic/group b/tests/generic/group
> index f0096bb..0a272b7 100644
> --- a/tests/generic/group
> +++ b/tests/generic/group
> @@ -420,3 +420,4 @@
> 415 auto clone
> 416 auto enospc
> 417 auto quick shutdown log
> +418 auto rw
> --
> 2.9.3
>