Date:   Mon, 12 Jun 2017 08:42:09 -0400
From:   Jeff Layton <jlayton@...hat.com>
To:     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,
        Chris Mason <clm@...com>, Josef Bacik <jbacik@...com>,
        David Sterba <dsterba@...e.com>,
        "Darrick J . Wong" <darrick.wong@...cle.com>,
        Eryu Guan <eguan@...hat.com>,
        David Howells <dhowells@...hat.com>
Cc:     linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
        linux-ext4@...r.kernel.org, linux-xfs@...r.kernel.org,
        linux-btrfs@...r.kernel.org, linux-block@...r.kernel.org
Subject: [xfstests PATCH v4 1/5] generic: add a writeback error handling test

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>
---
 .gitignore                 |   1 +
 common/dmerror             |  13 ++-
 doc/auxiliary-programs.txt |  16 ++++
 src/Makefile               |   2 +-
 src/dmerror                |  44 +++++++++
 src/fsync-err.c            | 223 +++++++++++++++++++++++++++++++++++++++++++++
 tests/generic/999          |  77 ++++++++++++++++
 tests/generic/999.out      |   3 +
 tests/generic/group        |   1 +
 9 files changed, 374 insertions(+), 6 deletions(-)
 create mode 100755 src/dmerror
 create mode 100644 src/fsync-err.c
 create mode 100755 tests/generic/999
 create mode 100644 tests/generic/999.out

diff --git a/.gitignore b/.gitignore
index 39664b0a7f53..56e863b2c8dc 100644
--- a/.gitignore
+++ b/.gitignore
@@ -72,6 +72,7 @@
 /src/fs_perms
 /src/fssum
 /src/fstest
+/src/fsync-err
 /src/fsync-tester
 /src/ftrunc
 /src/genhashnames
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..bcab453c4335 100644
--- a/doc/auxiliary-programs.txt
+++ b/doc/auxiliary-programs.txt
@@ -16,6 +16,8 @@ note the dependency with:
 Contents:
 
  - af_unix		-- Create an AF_UNIX socket
+ - dmerror		-- fault injection block device control
+ - 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 +32,20 @@ af_unix
 
 	The af_unix program creates an AF_UNIX socket at the given location.
 
+dmerror
+
+	dmerror is a program for creating, destroying and controlling a
+	fault injection device. The device can be set up as initially
+	working and then flip to throwing errors for testing purposes.
+
+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 6b0e4b022485..abd0fff34a64 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_fallocate
+	t_mmap_cow_race t_mmap_fallocate 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/dmerror b/src/dmerror
new file mode 100755
index 000000000000..4aaf682ee5f9
--- /dev/null
+++ b/src/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
diff --git a/src/fsync-err.c b/src/fsync-err.c
new file mode 100644
index 000000000000..5b3bdd3ada07
--- /dev/null
+++ b/src/fsync-err.c
@@ -0,0 +1,223 @@
+/*
+ * 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>
+#include <getopt.h>
+
+/*
+ * btrfs has a fixed stripewidth of 64k, so we need to write enough data to
+ * ensure that we hit both stripes by default.
+ */
+#define DEFAULT_BUFSIZE (65 * 1024)
+
+/* default number of fds to open */
+#define DEFAULT_NUM_FDS	10
+
+static void usage()
+{
+	printf("Usage: fsync-err [ -b bufsize ] [ -n num_fds ] -d dmerror path <filename>\n");
+}
+
+int main(int argc, char **argv)
+{
+	int *fd, ret, i, numfds = DEFAULT_NUM_FDS;
+	char *fname, *buf;
+	char *dmerror_path = NULL;
+	char *cmdbuf;
+	size_t cmdsize, bufsize = DEFAULT_BUFSIZE;
+
+	while ((i = getopt(argc, argv, "b:d:n:")) != -1) {
+		switch (i) {
+		case 'b':
+			bufsize = strtol(optarg, &buf, 0);
+			if (*buf != '\0') {
+				printf("bad string conversion: %s\n", optarg);
+				return 1;
+			}
+			break;
+		case 'd':
+			dmerror_path = optarg;
+			break;
+		case 'n':
+			numfds = strtol(optarg, &buf, 0);
+			if (*buf != '\0') {
+				printf("bad string conversion: %s\n", optarg);
+				return 1;
+			}
+			break;
+		}
+	}
+
+	if (argc < 1) {
+		usage();
+		return 1;
+	}
+
+	if (!dmerror_path) {
+		printf("Must specify dmerror path with -d option!\n");
+		return 1;
+	}
+
+	/* Remaining argument is filename */
+	fname = argv[optind];
+
+	fd = calloc(numfds, sizeof(*fd));
+	if (!fd) {
+		printf("malloc failed: %m\n");
+		return 1;
+	}
+
+	for (i = 0; i < numfds; ++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;
+	}
+
+	/* fill it with some junk */
+	memset(buf, 0x7c, bufsize);
+
+	for (i = 0; i < numfds; ++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 < numfds; ++i) {
+		ret = fsync(fd[i]);
+		if (ret < 0) {
+			printf("First fsync on fd[%d] failed: %m\n", i);
+			return 1;
+		}
+	}
+
+	/* enough for path + dmerror command string  (and then some) */
+	cmdsize = strlen(dmerror_path) + 64;
+
+	cmdbuf = malloc(cmdsize);
+	if (!cmdbuf) {
+		printf("malloc failed: %m\n");
+		return 1;
+	}
+
+	ret = snprintf(cmdbuf, cmdsize, "%s load_error_table", dmerror_path);
+	if (ret < 0 || ret >= cmdsize) {
+		printf("sprintf failure: %d\n", ret);
+		return 1;
+	}
+
+	/* flip the device to non-working mode */
+	ret = system(cmdbuf);
+	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 < numfds; ++i) {
+		ret = write(fd[i], buf, bufsize);
+		if (ret < 0) {
+			printf("Second write on fd[%d] failed: %m\n", i);
+			return 1;
+		}
+	}
+
+	for (i = 0; i < numfds; ++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 < numfds; ++i) {
+		ret = fsync(fd[i]);
+		if (ret < 0) {
+			/*
+			 * We did a failed write and fsync on each fd before.
+			 * Now the error should be clear since we've not done
+			 * any writes since then.
+			 */
+			printf("Third fsync on fd[%d] failed: %m\n", i);
+			return 1;
+		}
+	}
+
+	/* flip the device to working mode */
+	ret = snprintf(cmdbuf, cmdsize, "%s load_working_table", dmerror_path);
+	if (ret < 0 || ret >= cmdsize) {
+		printf("sprintf failure: %d\n", ret);
+		return 1;
+	}
+
+	ret = system(cmdbuf);
+	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 < numfds; ++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 < numfds; ++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..f998671ef19e
--- /dev/null
+++ b/tests/generic/999
@@ -0,0 +1,77 @@
+#! /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
+#-----------------------------------------------------------------------
+
+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
+_require_test_program dmerror
+
+rm -f $seqres.full
+
+echo "Format and mount"
+_scratch_mkfs > $seqres.full 2>&1
+_dmerror_init
+_dmerror_mount
+
+_require_fs_space $SCRATCH_MNT 65536
+
+testfile=$SCRATCH_MNT/fsync-err-test
+
+$here/src/fsync-err -d $here/src/dmerror $testfile
+
+# success, all done
+_dmerror_load_working_table
+_dmerror_unmount
+_dmerror_cleanup
+
+# fs may be corrupt after this -- attempt to repair it
+_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 5d3e4dcf732e..b56bae8f04f0 100644
--- a/tests/generic/group
+++ b/tests/generic/group
@@ -442,3 +442,4 @@
 437 auto quick
 438 auto
 439 auto quick punch
+999 auto quick
-- 
2.13.0

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