diff mbox

generic: test pagecache invalidation after direct write

Message ID 20170313065005.24401-1-eguan@redhat.com (mailing list archive)
State New, archived
Headers show

Commit Message

Eryu Guan March 13, 2017, 6:50 a.m. UTC
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>
---
 .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

Comments

Eryu Guan March 20, 2017, 7:29 a.m. UTC | #1
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
> 
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Brian Foster March 21, 2017, 3:11 p.m. UTC | #2
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>
> ---

Hi Eryu,

This mostly looks Ok to me. I notice the test takes just over 2m on a
test vm and seems to reproduce less than 50% of the time (only in a
handful of tries). Then again, it only requires 10s or so on a more high
end system, so that's pretty good. Either way, have you played around
with the tunables to either speed up the test and/or improve the
reproducibility?

Mostly nits and minor comments to follow...

>  .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)) {

If you're going to iterate the buffer a byte at a time, shouldn't
something like 'if (b1[1] != b2[i]) ...' be sufficient here?

> +			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);

			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]);

Hmm.. is it intentional to write the buf data to stderr and the newlines
to stdout? What does this look like if stderr is redirected?

> +	}
> +	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);

Why use n_child? It doesn't help us differentiate from other threads if
the values are incremented. Might be more simple to just use i + 1.

> +		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);
> +		}

pwrite()/pread() could eliminate the need for the lseek() calls. Also,
we probably want to check for short writes as well.

> +
> +		/* 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, "

Typo:							comparison

> +				"offset %d\n", n_child, i, (int)seekoff);
> +			ret += 1;

ret doesn't appear to be used after this.

> +			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();

Is sync() really necessary here? I'd expect fsync(fd) to be sufficient.

> +
> +	/* 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) {

			/* never returns */

> +			run_test(filename, i, blksz, offset, nr_iter,
> +				 flag_rd, flag_wr);
> +		} else {
> +			*(pids + i) = pid;

How about:		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

Typo:						       allocated

Brian

> +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
> 
> --
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Eryu Guan March 21, 2017, 3:52 p.m. UTC | #3
On Tue, Mar 21, 2017 at 11:11:52AM -0400, Brian Foster wrote:
> 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>
> > ---
> 
> Hi Eryu,
> 
> This mostly looks Ok to me. I notice the test takes just over 2m on a
> test vm and seems to reproduce less than 50% of the time (only in a
> handful of tries). Then again, it only requires 10s or so on a more high
> end system, so that's pretty good. Either way, have you played around
> with the tunables to either speed up the test and/or improve the
> reproducibility?

Yes, the original reproducer for the bug is quick and almost always
reproduces for me on my test vm.

runtest $((10 * LOAD_FACTOR)) -b $sectorsize -n 3 -i 1

I tuned the second test config, which adds more stress. I think current
config works best for me. It takes me around 3 minutes to finish and
doesn't lose too much stress.

runtest $((5 * LOAD_FACTOR))  -b $sectorsize -n 8 -i 4

> 
> Mostly nits and minor comments to follow...
> 
> >  .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)) {
> 
> If you're going to iterate the buffer a byte at a time, shouldn't
> something like 'if (b1[1] != b2[i]) ...' be sufficient here?

You're right, I must have copied this pattern from ltp test and
didn't think more about it.

> 
> > +			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);
> 
> 			pids[i] ?

Sure.

> 
> > +		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]);
> 
> Hmm.. is it intentional to write the buf data to stderr and the newlines
> to stdout? What does this look like if stderr is redirected?

No.. they both should go to stdout.

> 
> > +	}
> > +	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);
> 
> Why use n_child? It doesn't help us differentiate from other threads if
> the values are incremented. Might be more simple to just use i + 1.

Sure, will fix it.

> 
> > +		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);
> > +		}
> 
> pwrite()/pread() could eliminate the need for the lseek() calls. Also,
> we probably want to check for short writes as well.

OK.

> 
> > +
> > +		/* 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, "
> 
> Typo:							comparison

Will fix.

> 
> > +				"offset %d\n", n_child, i, (int)seekoff);
> > +			ret += 1;
> 
> ret doesn't appear to be used after this.

Originally there was no exit call in this error case, but I forgot to
remove the "ret += 1" when adding exit. Will fix it.

> 
> > +			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();
> 
> Is sync() really necessary here? I'd expect fsync(fd) to be sufficient.

Sure, will fix.

> 
> > +
> > +	/* 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) {
> 
> 			/* never returns */

OK.

> 
> > +			run_test(filename, i, blksz, offset, nr_iter,
> > +				 flag_rd, flag_wr);
> > +		} else {
> > +			*(pids + i) = pid;
> 
> How about:		pids[i] = pid;

Will fix.

> 
> > +		}
> > +	}
> > +
> > +	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
> 
> Typo:						       allocated

Will fix.

Thanks a lot for the review! I'll probably send v2 tomorrow.

Thanks,
Eryu

> 
> Brian
> 
> > +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
> > 
> > --
> > To unsubscribe from this list: send the line "unsubscribe fstests" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe fstests" in
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diff mbox

Patch

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