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Message-ID: <20170531185900.GB7903@u40b0340c692b58f6553c.ant.amazon.com>
Date: Wed, 31 May 2017 11:59:00 -0700
From: Eduardo Valentin <eduval@...zon.com>
To: Jeff Layton <jlayton@...hat.com>
CC: <fstests@...r.kernel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
"Al Viro" <viro@...IV.linux.org.uk>, Jan Kara <jack@...e.cz>,
<tytso@....edu>, <axboe@...nel.dk>, <mawilcox@...rosoft.com>,
<ross.zwisler@...ux.intel.com>, <corbet@....net>,
<dhowells@...hat.com>, <linux-ext4@...r.kernel.org>,
<linux-fsdevel@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<linux-block@...r.kernel.org>, <linux-doc@...r.kernel.org>
Subject: Re: [xfstests PATCH v3 1/5] generic: add a writeback error handling
test
Hello,
On Wed, May 31, 2017 at 09:08:16AM -0400, Jeff Layton wrote:
> I'm working on a set of kernel patches to change how writeback errors
> are handled and reported in the kernel. Instead of reporting a
> writeback error to only the first fsync caller on the file, I aim
> to make the kernel report them once on every file description.
>
> This patch adds a test for the new behavior. Basically, open many fds
> to the same file, turn on dm_error, write to each of the fds, and then
> fsync them all to ensure that they all get an error back.
>
> To do that, I'm adding a new tools/dmerror script that the C program
> can use to load the error table. For now, that's all it can do, but
> we can fill it out with other commands as necessary.
>
> Signed-off-by: Jeff Layton <jlayton@...hat.com>
> ---
> common/dmerror | 13 ++--
> doc/auxiliary-programs.txt | 8 +++
> src/Makefile | 2 +-
> src/fsync-err.c | 161 +++++++++++++++++++++++++++++++++++++++++++++
> tests/generic/999 | 76 +++++++++++++++++++++
> tests/generic/999.out | 3 +
> tests/generic/group | 1 +
> tools/dmerror | 44 +++++++++++++
> 8 files changed, 302 insertions(+), 6 deletions(-)
> create mode 100644 src/fsync-err.c
> create mode 100755 tests/generic/999
> create mode 100644 tests/generic/999.out
> create mode 100755 tools/dmerror
>
> diff --git a/common/dmerror b/common/dmerror
> index d46c5d0b7266..238baa213b1f 100644
> --- a/common/dmerror
> +++ b/common/dmerror
> @@ -23,22 +23,25 @@ if [ $? -eq 0 ]; then
> _notrun "Cannot run tests with DAX on dmerror devices"
> fi
>
> -_dmerror_init()
> +_dmerror_setup()
> {
> local dm_backing_dev=$SCRATCH_DEV
>
> - $DMSETUP_PROG remove error-test > /dev/null 2>&1
> -
> local blk_dev_size=`blockdev --getsz $dm_backing_dev`
>
> DMERROR_DEV='/dev/mapper/error-test'
>
> DMLINEAR_TABLE="0 $blk_dev_size linear $dm_backing_dev 0"
>
> + DMERROR_TABLE="0 $blk_dev_size error $dm_backing_dev 0"
> +}
> +
> +_dmerror_init()
> +{
> + _dmerror_setup
> + $DMSETUP_PROG remove error-test > /dev/null 2>&1
> $DMSETUP_PROG create error-test --table "$DMLINEAR_TABLE" || \
> _fatal "failed to create dm linear device"
> -
> - DMERROR_TABLE="0 $blk_dev_size error $dm_backing_dev 0"
> }
>
> _dmerror_mount()
> diff --git a/doc/auxiliary-programs.txt b/doc/auxiliary-programs.txt
> index 21ef118596b6..191ac0596511 100644
> --- a/doc/auxiliary-programs.txt
> +++ b/doc/auxiliary-programs.txt
> @@ -16,6 +16,7 @@ note the dependency with:
> Contents:
>
> - af_unix -- Create an AF_UNIX socket
> + - fsync-err -- tests fsync error reporting after failed writeback
> - open_by_handle -- open_by_handle_at syscall exercise
> - stat_test -- statx syscall exercise
> - t_dir_type -- print directory entries and their file type
> @@ -30,6 +31,13 @@ af_unix
>
> The af_unix program creates an AF_UNIX socket at the given location.
>
> +fsync-err
> + Specialized program for testing how the kernel reports errors that
> + occur during writeback. Works in conjunction with the dmerror script
> + in tools/ to write data to a device, and then force it to fail
> + writeback and test that errors are reported during fsync and cleared
> + afterward.
> +
> open_by_handle
>
> The open_by_handle program exercises the open_by_handle_at() system
> diff --git a/src/Makefile b/src/Makefile
> index 4ec01975f8f7..b79c4d84d31b 100644
> --- a/src/Makefile
> +++ b/src/Makefile
> @@ -13,7 +13,7 @@ TARGETS = dirstress fill fill2 getpagesize holes lstat64 \
> multi_open_unlink dmiperf unwritten_sync genhashnames t_holes \
> t_mmap_writev t_truncate_cmtime dirhash_collide t_rename_overwrite \
> holetest t_truncate_self t_mmap_dio af_unix t_mmap_stale_pmd \
> - t_mmap_cow_race
> + t_mmap_cow_race fsync-err
>
> LINUX_TARGETS = xfsctl bstat t_mtab getdevicesize preallo_rw_pattern_reader \
> preallo_rw_pattern_writer ftrunc trunc fs_perms testx looptest \
> diff --git a/src/fsync-err.c b/src/fsync-err.c
> new file mode 100644
> index 000000000000..cbeb37fb1790
> --- /dev/null
> +++ b/src/fsync-err.c
> @@ -0,0 +1,161 @@
> +/*
> + * fsync-err.c: test whether writeback errors are reported to all open fds
> + * and properly cleared as expected after being seen once on each
> + *
> + * Copyright (c) 2017: Jeff Layton <jlayton@...hat.com>
> + */
> +#include <sys/types.h>
> +#include <sys/stat.h>
> +#include <errno.h>
> +#include <fcntl.h>
> +#include <stdlib.h>
> +#include <stdio.h>
> +#include <string.h>
> +#include <unistd.h>
> +
> +/*
> + * btrfs has a fixed stripewidth of 64k, so we need to write enough data to
> + * ensure that we hit both stripes.
> + *
> + * FIXME: have the test script pass in the length?
> + */
> +#define BUFSIZE (65 * 1024)
> +
> +/* FIXME: should this be tunable */
> +#define NUM_FDS 10
> +
> +static void usage() {
> + fprintf(stderr, "Usage: fsync-err <filename>\n");
> +}
Just to follow the same style as your main:
+static void usage()
+{
+ fprintf(stderr, "Usage: fsync-err <filename>\n");
+}
> +
> +int main(int argc, char **argv)
> +{
> + int fd[NUM_FDS], ret, i;
> + char *fname, *buf;
> +
> + if (argc < 1) {
> + usage();
> + return 1;
> + }
> +
> + /* First argument is filename */
> + fname = argv[1];
> +
> + for (i = 0; i < NUM_FDS; ++i) {
> + fd[i] = open(fname, O_WRONLY | O_CREAT | O_TRUNC, 0644);
> + if (fd[i] < 0) {
> + printf("open of fd[%d] failed: %m\n", i);
> + return 1;
> + }
> + }
> +
> + buf = malloc(BUFSIZE);
> + if (!buf) {
> + printf("malloc failed: %m\n");
> + return 1;
> + }
> +
> + memset(buf, 0x7c, BUFSIZE);
> +
> + for (i = 0; i < NUM_FDS; ++i) {
> + ret = write(fd[i], buf, BUFSIZE);
> + if (ret < 0) {
> + printf("First write on fd[%d] failed: %m\n", i);
> + return 1;
> + }
> + }
> +
> + for (i = 0; i < NUM_FDS; ++i) {
> + ret = fsync(fd[i]);
> + if (ret < 0) {
> + printf("First fsync on fd[%d] failed: %m\n", i);
> + return 1;
> + }
> + }
> +
> + /* flip the device to non-working mode */
> + ret = system("./tools/dmerror load_error_table");
Just assuming a hardcoded relative path?
> + if (ret) {
> + if (WIFEXITED(ret))
> + printf("system: program exited: %d\n",
> + WEXITSTATUS(ret));
> + else
> + printf("system: 0x%x\n", (int)ret);
> +
> + return 1;
> + }
> +
> + for (i = 0; i < NUM_FDS; ++i) {
> + ret = write(fd[i], buf, strlen(buf) + 1);
Why not BUFSIZE here?
> + if (ret < 0) {
> + printf("Second write on fd[%d] failed: %m\n", i);
> + return 1;
> + }
> + }
> +
> + for (i = 0; i < NUM_FDS; ++i) {
> + ret = fsync(fd[i]);
> + /* Now, we EXPECT the error! */
> + if (ret >= 0) {
> + printf("Success on second fsync on fd[%d]!\n", i);
> + return 1;
> + }
> + }
> +
> + for (i = 0; i < NUM_FDS; ++i) {
> + ret = fsync(fd[i]);
> + if (ret < 0) {
> + /* Now the error should be clear */
> + printf("Third fsync on fd[%d] failed: %m\n", i);
> + return 1;
> + }
> + }
> +
> + /* flip the device to working mode */
> + ret = system("./tools/dmerror load_working_table");
> + if (ret) {
> + if (WIFEXITED(ret))
> + printf("system: program exited: %d\n",
> + WEXITSTATUS(ret));
> + else
> + printf("system: 0x%x\n", (int)ret);
> +
> + return 1;
> + }
> +
> + for (i = 0; i < NUM_FDS; ++i) {
> + ret = fsync(fd[i]);
> + if (ret < 0) {
> + /* The error should still be clear */
> + printf("fsync after healing device on fd[%d] failed: %m\n", i);
> + return 1;
> + }
> + }
> +
> + /*
> + * reopen each file one at a time to ensure the same inode stays
> + * in core. fsync each one to make sure we see no errors on a fresh
> + * open of the inode.
> + */
> + for (i = 0; i < NUM_FDS; ++i) {
> + ret = close(fd[i]);
> + if (ret < 0) {
> + printf("Close of fd[%d] returned unexpected error: %m\n", i);
> + return 1;
> + }
> + fd[i] = open(fname, O_WRONLY | O_CREAT | O_TRUNC, 0644);
> + if (fd[i] < 0) {
> + printf("Second open of fd[%d] failed: %m\n", i);
> + return 1;
> + }
> + ret = fsync(fd[i]);
> + if (ret < 0) {
> + /* New opens should not return an error */
> + printf("First fsync after reopen of fd[%d] failed: %m\n", i);
> + return 1;
> + }
> + }
> +
> + printf("Test passed!\n");
> + return 0;
> +}
> diff --git a/tests/generic/999 b/tests/generic/999
> new file mode 100755
> index 000000000000..6de143d1149e
> --- /dev/null
> +++ b/tests/generic/999
> @@ -0,0 +1,76 @@
> +#! /bin/bash
> +# FS QA Test No. 999
> +#
> +# Open a file several times, write to it, fsync on all fds and make sure that
> +# they all return 0. Change the device to start throwing errors. Write again
> +# on all fds and fsync on all fds. Ensure that we get errors on all of them.
> +# Then fsync on all one last time and verify that all return 0.
> +#
> +#-----------------------------------------------------------------------
> +# Copyright (c) 2017, Jeff Layton <jlayton@...hat.com>
> +#
> +# 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
> +#-----------------------------------------------------------------------
Sure you want to track the address? Maybe just remove it?
> +
> +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 -rf $tmp.* $testdir
> + _dmerror_cleanup
> +}
> +
> +# get standard environment, filters and checks
> +. ./common/rc
> +. ./common/filter
> +. ./common/dmerror
> +
> +# real QA test starts here
> +_supported_os Linux
> +_require_scratch
> +_require_logdev
> +_require_dm_target error
> +_require_test_program fsync-err
> +
> +rm -f $seqres.full
> +
> +echo "Format and mount"
> +$XFS_IO_PROG -d -c "pwrite -S 0x7c -b 1048576 0 $((64 * 1048576))" $SCRATCH_DEV >> $seqres.full
> +_scratch_mkfs > $seqres.full 2>&1
> +_dmerror_init
> +_dmerror_mount >> $seqres.full 2>&1
> +_dmerror_unmount
> +_dmerror_mount
> +
> +_require_fs_space $SCRATCH_MNT 8192
> +
> +testfile=$SCRATCH_MNT/fsync-err-test
> +
> +$here/src/fsync-err $testfile
> +
> +# success, all done
> +_dmerror_load_working_table
> +_dmerror_unmount
> +_dmerror_cleanup
> +_repair_scratch_fs >> $seqres.full
> +status=0
> +exit
> diff --git a/tests/generic/999.out b/tests/generic/999.out
> new file mode 100644
> index 000000000000..2e48492ff6d1
> --- /dev/null
> +++ b/tests/generic/999.out
> @@ -0,0 +1,3 @@
> +QA output created by 999
> +Format and mount
> +Test passed!
> diff --git a/tests/generic/group b/tests/generic/group
> index 438c299030f2..39f7b14657f1 100644
> --- a/tests/generic/group
> +++ b/tests/generic/group
> @@ -440,3 +440,4 @@
> 435 auto encrypt
> 436 auto quick rw
> 437 auto quick
> +999 auto quick
> diff --git a/tools/dmerror b/tools/dmerror
> new file mode 100755
> index 000000000000..4aaf682ee5f9
> --- /dev/null
> +++ b/tools/dmerror
> @@ -0,0 +1,44 @@
> +#!/bin/bash
> +#-----------------------------------------------------------------------
> +# Copyright (c) 2017, Jeff Layton <jlayton@...hat.com>
> +#
> +# 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
> +#-----------------------------------------------------------------------
> +
> +. ./common/config
> +. ./common/dmerror
> +
> +_dmerror_setup
> +
> +case $1 in
> +cleanup)
> + _dmerror_cleanup
> + ;;
> +init)
> + _dmerror_init
> + ;;
> +load_error_table)
> + _dmerror_load_error_table
> + ;;
> +load_working_table)
> + _dmerror_load_working_table
> + ;;
> +*)
> + echo "Usage: $0 {init|cleanup|load_error_table|load_working_table}"
> + exit 1
> + ;;
> +esac
> +
> +status=0
> +exit
> --
> 2.9.4
>
>
--
All the best,
Eduardo Valentin
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