From: Eduardo Valentin Subject: Re: [xfstests PATCH v3 1/5] generic: add a writeback error handling test Date: Wed, 31 May 2017 11:59:00 -0700 Message-ID: <20170531185900.GB7903@u40b0340c692b58f6553c.ant.amazon.com> References: <20170531130820.17634-1-jlayton@redhat.com> <20170531130820.17634-2-jlayton@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: , Andrew Morton , "Al Viro" , Jan Kara , , , , , , , , , , , To: Jeff Layton Return-path: Content-Disposition: inline In-Reply-To: <20170531130820.17634-2-jlayton@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org 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 > --- > 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 > + */ > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +/* > + * 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 \n"); > +} Just to follow the same style as your main: +static void usage() +{ + fprintf(stderr, "Usage: fsync-err \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 > +# > +# 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 > +# > +# 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