diff mbox

xfstests 311: test fsync with dm flakey

Message ID 1366665213-17894-1-git-send-email-jbacik@fusionio.com (mailing list archive)
State Not Applicable
Headers show

Commit Message

Josef Bacik April 22, 2013, 9:13 p.m. UTC
This test sets up a dm flakey target and then runs my fsync tester I've been
using to verify btrfs's fsync() is working properly.  It will create a dm flakey
device, mount it, run my test, make the flakey device start dropping writes, and
then unmount the fs.  Then we mount it back up and make sure the md5sums match
and then run fsck on the device to make sure we got a consistent fs.  I used the
output from a run on XFS since I assume at this point XFS's fsync() is working
properly.  If it's not then I'll fix it up and resend, but this at least gives
everybody an idea of where I'm going.  Any comments are welcome.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
---
 common/config         |    1 +
 common/punch          |    7 -
 common/rc             |   28 +++
 src/Makefile          |    2 +-
 src/fsync-tester.c    |  538 +++++++++++++++++++++++++++++++++++++++++++++++++
 tests/generic/311     |  177 ++++++++++++++++
 tests/generic/311.out |  193 ++++++++++++++++++
 tests/generic/group   |    1 +
 8 files changed, 939 insertions(+), 8 deletions(-)
 create mode 100644 src/fsync-tester.c
 create mode 100755 tests/generic/311
 create mode 100644 tests/generic/311.out
diff mbox

Patch

diff --git a/common/config b/common/config
index dfbb5c2..b8ab593 100644
--- a/common/config
+++ b/common/config
@@ -177,6 +177,7 @@  export FIO_PROG="`set_prog_path fio`"
 export FILEFRAG_PROG="`set_prog_path filefrag`"
 export E4DEFRAG_PROG="`set_prog_path e4defrag`"
 export LOGGER_PROG="`set_prog_path logger`"
+export DMSETUP_PROG="`set_prog_path dmsetup`"
 
 # Generate a comparable xfsprogs version number in the form of
 # major * 10000 + minor * 100 + release
diff --git a/common/punch b/common/punch
index cfbe576..b9f9acd 100644
--- a/common/punch
+++ b/common/punch
@@ -234,13 +234,6 @@  _filter_hole_fiemap()
 	_coalesce_extents
 }
 
-
-# Prints the md5 checksum of a given file
-_md5_checksum()
-{
-	md5sum $1 | cut -d ' ' -f1
-}
-
 _filter_bmap()
 {
 	awk '
diff --git a/common/rc b/common/rc
index b980697..f12aaa1 100644
--- a/common/rc
+++ b/common/rc
@@ -57,6 +57,13 @@  dd()
    fi
 }
 
+# Prints the md5 checksum of a given file
+_md5_checksum()
+{
+	md5sum $1 | cut -d ' ' -f1
+}
+
+
 # ls -l w/ selinux sometimes puts a dot at the end:
 # -rwxrw-r--. id1 id2 file1
 
@@ -1041,6 +1048,27 @@  _require_command()
     [ -n "$1" -a -x "$1" ] || _notrun "$_cmd utility required, skipped this test"
 }
 
+# this test requires the device mapper flakey target
+#
+_require_dm_flakey()
+{
+    if [ "$HOSTOS" != "Linux" ]
+    then
+	_notrun "This test requires linux for dm flakey support"
+    fi
+
+    _require_command $DMSETUP_PROG
+
+    modprobe dm-flakey >/dev/null 2>&1
+    $DMSETUP_PROG targets | grep flakey >/dev/null 2>&1
+    if [ $? -eq 0 ]
+    then
+	:
+    else
+	_notrun "This test requires dm flakey support"
+    fi
+}
+
 # this test requires the projid32bit feature to be available in
 # mkfs.xfs
 #
diff --git a/src/Makefile b/src/Makefile
index 8d8e97f..c18ffc9 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -18,7 +18,7 @@  LINUX_TARGETS = xfsctl bstat t_mtab getdevicesize preallo_rw_pattern_reader \
 	locktest unwritten_mmap bulkstat_unlink_test t_stripealign \
 	bulkstat_unlink_test_modified t_dir_offset t_futimens t_immutable \
 	stale_handle pwrite_mmap_blocked t_dir_offset2 seek_sanity_test \
-	seek_copy_test t_readdir_1 t_readdir_2
+	seek_copy_test t_readdir_1 t_readdir_2 fsync-tester
 
 SUBDIRS =
 
diff --git a/src/fsync-tester.c b/src/fsync-tester.c
new file mode 100644
index 0000000..1b03e02
--- /dev/null
+++ b/src/fsync-tester.c
@@ -0,0 +1,538 @@ 
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+
+static int test_fd;
+static char *buf;
+static char *fname;
+
+/*
+ * Just creates a random file, overwriting the file in a random number of loops
+ * and fsyncing between each loop.
+ */
+static int test_one(int *max_blocks)
+{
+	int loops = (random() % 20) + 5;
+
+	lseek(test_fd, 0, SEEK_SET);
+	while (loops--) {
+		int character = (random() % 126) + 33; /* printable character */
+		int blocks = (random() % 100) + 1;
+
+		if (blocks > *max_blocks)
+			*max_blocks = blocks;
+		lseek(test_fd, 0, SEEK_SET);
+		memset(buf, character, 4096);
+		if (fsync(test_fd)) {
+			fprintf(stderr, "Fsync failed, test results will be "
+				"invalid: %d\n", errno);
+			return 1;
+		}
+
+		while (blocks--) {
+			if (write(test_fd, buf, 4096) < 4096) {
+				fprintf(stderr, "Short write %d\n", errno);
+				return 1;
+			}
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * Preallocate a randomly sized file and then overwrite the entire thing and
+ * then fsync.
+ */
+static int test_two(int *max_blocks)
+{
+	int blocks = (random() % 1024) + 1;
+	int character = (random() % 126) + 33;
+
+	*max_blocks = blocks;
+
+	if (fallocate(test_fd, 0, 0, blocks * 4096)) {
+		fprintf(stderr, "Error fallocating %d (%s)\n", errno,
+			strerror(errno));
+		return 1;
+	}
+
+	lseek(test_fd, 0, SEEK_SET);
+	memset(buf, character, 4096);
+	while (blocks--) {
+		if (write(test_fd, buf, 4096) < 4096) {
+			fprintf(stderr, "Short write %d\n", errno);
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+static void drop_all_caches()
+{
+	int value = 3;
+	int fd;
+
+	if ((fd = open("/proc/sys/vm/drop_caches", O_WRONLY)) < 0) {
+		fprintf(stderr, "Error opening drop caches: %d\n", errno);
+		return;
+	}
+
+	write(fd, &value, sizeof(int));
+	close(fd);
+}
+
+/*
+ * Randomly write inside of a file, either creating a sparse file or prealloc
+ * the file and randomly write within it, depending on the prealloc flag
+ */
+static int test_three(int *max_blocks, int prealloc, int rand_fsync,
+		      int sync, int drop_caches)
+{
+	int size = (random() % 2048) + 4;
+	int blocks = size / 2;
+	int sync_block = blocks / 2;
+	int rand_sync_interval = (random() % blocks) + 1;
+	int character = (random() % 126) + 33;
+
+	printf("Size is %d, blocks is %d\n", size, blocks);
+	if (prealloc && fallocate(test_fd, 0, 0, size * 4096)) {
+		fprintf(stderr, "Error fallocating %d (%s)\n", errno,
+			strerror(errno));
+		return 1;
+	}
+
+	if (prealloc)
+		*max_blocks = size;
+
+	memset(buf, character, 4096);
+	while (blocks--) {
+		int block = (random() % size);
+
+		if ((block + 1) > *max_blocks)
+			*max_blocks = block + 1;
+
+		if (rand_fsync && !(blocks % rand_sync_interval)) {
+			if (fsync(test_fd)) {
+				fprintf(stderr, "Fsync failed, test results "
+					"will be invalid: %d\n", errno);
+				return 1;
+			}
+		}
+
+		/* Force a transaction commit in between just for fun */
+		if (blocks == sync_block && (sync || drop_caches)) {
+			if (sync)
+				syncfs(test_fd);
+			else
+				sync_file_range(test_fd, 0, 0,
+						SYNC_FILE_RANGE_WRITE|
+						SYNC_FILE_RANGE_WAIT_AFTER);
+
+			if (drop_caches) {
+				close(test_fd);
+				drop_all_caches();
+				test_fd = open(fname, O_RDWR);
+				if (test_fd < 0) {
+					test_fd = 0;
+					fprintf(stderr, "Error re-opening file: %d\n",
+						errno);
+					return 1;
+				}
+			}
+		}
+
+		if (pwrite(test_fd, buf, 4096, block * 4096) < 4096) {
+			fprintf(stderr, "Short write %d\n", errno);
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+static void timeval_subtract(struct timeval *result,struct timeval *x,
+			     struct timeval *y)
+{
+	if (x->tv_usec < y->tv_usec) {
+		int nsec = (y->tv_usec - x->tv_usec) / 1000000 + 1;
+		y->tv_usec -= 1000000 * nsec;
+		y->tv_sec += nsec;
+	}
+
+	if (x->tv_usec - y->tv_usec > 1000000) {
+		int nsec = (x->tv_usec - y->tv_usec) / 1000000;
+		y->tv_usec += 1000000 * nsec;
+		y->tv_sec -= nsec;
+	}
+
+	result->tv_sec = x->tv_sec - y->tv_sec;
+	result->tv_usec = x->tv_usec - y->tv_usec;
+}
+
+static int test_four(int *max_blocks)
+{
+	size_t size = 2621440;	/* 10 gigabytes */
+	size_t blocks = size / 2;
+	size_t sync_block = blocks / 8;	/* fsync 8 times */
+	int character = (random() % 126) + 33;
+	struct timeval start, end, diff;
+
+	memset(buf, character, 4096);
+	while (blocks--) {
+		off_t block = (random() % size);
+
+		if ((block + 1) > *max_blocks)
+			*max_blocks = block + 1;
+
+		if ((blocks % sync_block) == 0) {
+			if (gettimeofday(&start, NULL)) {
+				fprintf(stderr, "Error getting time: %d\n",
+					errno);
+				return 1;
+			}
+			if (fsync(test_fd)) {
+				fprintf(stderr, "Fsync failed, test results "
+					"will be invalid: %d\n", errno);
+				return 1;
+			}
+			if (gettimeofday(&end, NULL)) {
+				fprintf(stderr, "Error getting time: %d\n",
+					errno);
+				return 1;
+			}
+			timeval_subtract(&diff, &end, &start);
+			printf("Fsync time was %ds and %dus\n",
+			       (int)diff.tv_sec, (int)diff.tv_usec);
+		}
+
+		if (pwrite(test_fd, buf, 4096, block * 4096) < 4096) {
+			fprintf(stderr, "Short write %d\n", errno);
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+static int test_five()
+{
+	int character = (random() % 126) + 33;
+	int runs = (random() % 100) + 1;
+	int i;
+
+	memset(buf, character, 3072);
+	for (i = 0; i < runs; i++) {
+		size_t write_size = (random() % 3072) + 1;
+
+		if (pwrite(test_fd, buf, write_size, 0) < write_size) {
+			fprintf(stderr, "Short write %d\n", errno);
+			return 1;
+		}
+
+		if ((i % 8) == 0) {
+			if (fsync(test_fd)) {
+				fprintf(stderr, "Fsync failed, test results "
+					"will be invalid: %d\n", errno);
+				return 1;
+			}
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * Reproducer for something like this
+ *
+ * [data][prealloc][data]
+ *
+ * and then in the [prealloc] section we have
+ *
+ * [ pre ][pre][     pre     ]
+ * [d][pp][dd][ppp][d][ppp][d]
+ *
+ * where each letter represents on block of either data or prealloc.
+ *
+ * This explains all the weirdly specific numbers.
+ */
+static int test_six()
+{
+	int character = (random() % 126) + 33;
+	int i;
+
+	memset(buf, character, 4096);
+
+	/* Write on either side of the file, leaving a hole in the middle */
+	for (i = 0; i < 10; i++) {
+		if (pwrite(test_fd, buf, 4096, i * 4096) < 4096) {
+			fprintf(stderr, "Short write %d\n", errno);
+			return 1;
+		}
+	}
+
+	if (fsync(test_fd)) {
+		fprintf(stderr, "Fsync failed %d\n", errno);
+		return 1;
+	}
+
+	/*
+	 * The test fs I had the prealloc extent was 13 4k blocks long so I'm
+	 * just using that to give myself the best chances of reproducing.
+	 */
+	for (i = 23; i < 33; i++) {
+		if (pwrite(test_fd, buf, 4096, i * 4096) < 4096) {
+			fprintf(stderr, "Short write %d\n", errno);
+			return 1;
+		}
+	}
+
+	if (fsync(test_fd)) {
+		fprintf(stderr, "Fsync failed %d\n", errno);
+		return 1;
+	}
+
+	if (fallocate(test_fd, 0, 10 * 4096, 4 * 4096)) {
+		fprintf(stderr, "Error fallocating %d\n", errno);
+		return 1;
+	}
+
+	if (fallocate(test_fd, 0, 14 * 4096, 5 * 4096)) {
+		fprintf(stderr, "Error fallocating %d\n", errno);
+		return 1;
+	}
+
+	if (fallocate(test_fd, 0, 19 * 4096, 4 * 4096)) {
+		fprintf(stderr, "Error fallocating %d\n", errno);
+		return 1;
+	}
+
+	if (pwrite(test_fd, buf, 4096, 10 * 4096) < 4096) {
+		fprintf(stderr, "Short write %d\n", errno);
+		return 1;
+	}
+
+	if (fsync(test_fd)) {
+		fprintf(stderr, "Fsync failed %d\n", errno);
+		return 1;
+	}
+
+	for (i = 13; i < 15; i++) {
+		if (pwrite(test_fd, buf, 4096, i * 4096) < 4096) {
+			fprintf(stderr, "Short write %d\n", errno);
+			return 1;
+		}
+	}
+
+	if (fsync(test_fd)) {
+		fprintf(stderr, "Fsync failed %d\n", errno);
+		return 1;
+	}
+
+	if (pwrite(test_fd, buf, 4096, 18 * 4096) < 4096) {
+		fprintf(stderr, "Short write %d\n", errno);
+		return 1;
+	}
+
+	if (fsync(test_fd)) {
+		fprintf(stderr, "Fsync failed %d\n", errno);
+		return 1;
+	}
+
+	if (pwrite(test_fd, buf, 4096, 22 * 4096) < 4096) {
+		fprintf(stderr, "Short write %d\n", errno);
+		return 1;
+	}
+
+	if (fsync(test_fd)) {
+		fprintf(stderr, "Fsync failed %d\n", errno);
+		return 1;
+	}
+
+	return 0;
+}
+
+static void usage()
+{
+	printf("Usage fsync-tester [-s <seed>] [-r] [-d] -t <test-num> <filename>\n");
+	printf("   -s seed   : seed for teh random map generator (defaults to reading /dev/urandom)\n");
+	printf("   -r        : don't reboot the box immediately\n");
+	printf("   -d        : use O_DIRECT\n");
+	printf("   -t test   : test nr to run, required\n");
+	exit(1);
+}
+
+int main(int argc, char **argv)
+{
+	int opt;
+	int fd;
+	int max_blocks = 0;
+	char *endptr;
+	unsigned int seed = 123;
+	int reboot = 1;
+	int direct_io = 0;
+	long int test = 1;
+	long int tmp;
+	int ret = 0;
+	int flags = O_RDWR|O_CREAT|O_TRUNC;
+
+	if (argc < 2)
+		usage();
+
+	fd = open("/dev/urandom", O_RDONLY);
+	if (fd >= 0) {
+		read(fd, &seed, sizeof(seed));
+		close(fd);
+	}
+
+	while ((opt = getopt(argc, argv, "s:rdt:")) != -1) {
+		switch (opt) {
+		case 's':
+			tmp = strtol(optarg, &endptr, 10);
+			if (tmp == LONG_MAX || endptr == optarg)
+				usage();
+			seed = tmp;
+			break;
+		case 'r':
+			reboot = 0;
+			break;
+		case 'd':
+			direct_io = 1;
+			break;
+		case 't':
+			test = strtol(optarg, &endptr, 10);
+			if (test == LONG_MAX || endptr == optarg)
+				usage();
+			break;
+		default:
+			usage();
+		}
+	}
+
+	if (optind >= argc)
+		usage();
+
+	fname = argv[optind];
+	if (!fname)
+		usage();
+
+	printf("Random seed is %u\n", seed);
+	srandom(seed);
+
+	if (direct_io) {
+		flags |= O_DIRECT;
+		ret = posix_memalign((void **)&buf, getpagesize(), 4096);
+		if (ret)
+			buf = NULL;
+	} else {
+		buf = malloc(4096);
+	}
+
+	if (!buf) {
+		fprintf(stderr, "Error allocating buf: %d\n", errno);
+		return 1;
+	}
+
+	test_fd = open(fname, flags, 0644);
+	if (test_fd < 0) {
+		fprintf(stderr, "Error opening file %d (%s)\n", errno,
+			strerror(errno));
+		return 1;
+	}
+
+	switch (test) {
+	case 1:
+		ret = test_one(&max_blocks);
+		break;
+	case 2:
+		ret = test_two(&max_blocks);
+		break;
+	case 3:
+		ret = test_three(&max_blocks, 0, 0, 0, 0);
+		break;
+	case 4:
+		ret = test_three(&max_blocks, 1, 0, 0, 0);
+		break;
+	case 5:
+		ret = test_three(&max_blocks, 0, 1, 0, 0);
+		break;
+	case 6:
+		ret = test_three(&max_blocks, 1, 1, 0, 0);
+		break;
+	case 7:
+		ret = test_three(&max_blocks, 0, 0, 1, 0);
+		break;
+	case 8:
+		ret = test_three(&max_blocks, 1, 0, 1, 0);
+		break;
+	case 9:
+		ret = test_three(&max_blocks, 0, 1, 1, 0);
+		break;
+	case 10:
+		ret = test_three(&max_blocks, 1, 1, 1, 0);
+		break;
+	case 11:
+		ret = test_three(&max_blocks, 0, 0, 0, 1);
+		break;
+	case 12:
+		ret = test_three(&max_blocks, 0, 1, 0, 1);
+		break;
+	case 13:
+		ret = test_three(&max_blocks, 0, 0, 1, 1);
+		break;
+	case 14:
+		ret = test_three(&max_blocks, 0, 1, 1, 1);
+		break;
+	case 15:
+		ret = test_three(&max_blocks, 1, 0, 0, 1);
+		break;
+	case 16:
+		ret = test_three(&max_blocks, 1, 1, 0, 1);
+		break;
+	case 17:
+		ret = test_three(&max_blocks, 1, 0, 1, 1);
+		break;
+	case 18:
+		ret = test_three(&max_blocks, 1, 1, 1, 1);
+		break;
+	case 19:
+		ret = test_five();
+		break;
+	case 20:
+		ret = test_six();
+		break;
+	case 21:
+		/*
+		 * This is just a perf test, keep moving it down so it's always
+		 * the last test option.
+		 */
+		reboot = 0;
+		ret = test_four(&max_blocks);
+		goto out;
+	default:
+		usage();
+	}
+
+	if (ret)
+		goto out;
+
+	if (fsync(test_fd)) {
+		fprintf(stderr, "Fsync failed, test results will be invalid: "
+			"%d\n", errno);
+		return 1;
+	}
+	if (reboot)
+		system("reboot -fn");
+out:
+	free(buf);
+	close(test_fd);
+	return ret;
+}
diff --git a/tests/generic/311 b/tests/generic/311
new file mode 100755
index 0000000..165d852
--- /dev/null
+++ b/tests/generic/311
@@ -0,0 +1,177 @@ 
+#! /bin/bash
+# FS QA Test No. 311
+#
+#Verify a file systems fsync is working properly.  This won't catch problems
+#with blockdev flushing, but at the very least it makes sure the file system is
+#doing the right thing with fsync logically.
+#
+#-----------------------------------------------------------------------
+# Copyright (c) 2013 Fusion IO. 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
+#-----------------------------------------------------------------------
+#
+# creator
+owner=jbacik@fusionio.com
+
+seq=`basename $0`
+seqres=$RESULT_DIR/$seq
+echo "QA output created by $seq"
+
+here=`pwd`
+status=1	# failure is the default!
+
+_cleanup()
+{
+	$UMOUNT_PROG $SCRATCH_MNT > /dev/null 2>&1
+	$DMSETUP_PROG remove flakey-test > /dev/null 2>&1
+}
+
+_cleanup
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+
+# real QA test starts here
+_supported_fs generic
+_supported_os Linux
+_need_to_be_root
+_require_scratch
+_require_dm_flakey
+
+[ -x $here/src/fsync-tester ] || _notrun "fsync-tester not build"
+
+rm -f $seqres.full
+BLK_DEV_SIZE=`blockdev --getsz $SCRATCH_DEV`
+FLAKEY_DEV=/dev/mapper/flakey-test
+SEED=1
+testfile=$SCRATCH_MNT/$seq.fsync
+
+_mount_flakey()
+{
+	_scratch_options mount
+	_mount -t $FSTYP $SCRATCH_OPTIONS $MOUNT_OPTIONS $SELINUX_MOUNT_OPTIONS $* $FLAKEY_DEV $SCRATCH_MNT
+}
+
+_unmount_flakey()
+{
+	$UMOUNT_PROG $FLAKEY_DEV
+}
+_drop_writes()
+{
+	$DMSETUP_PROG suspend flakey-test
+	if [ $? -ne 0 ]; then
+		echo "failed to suspend flakey-test"
+		_unmount_flakey
+		_cleanup
+		exit
+	fi
+	$DMSETUP_PROG load flakey-test --table "0 $BLK_DEV_SIZE flakey $SCRATCH_DEV 0 0 180 1 drop_writes"
+	if [ $? -ne 0 ]; then
+		echo "failed to load table into flakey-test"
+		_unmount_flakey
+		_cleanup
+		exit
+	fi
+	$DMSETUP_PROG resume flakey-test
+	if [ $? -ne 0 ]; then
+		echo "failed to resumeflakey-test"
+		_unmount_flakey
+		_cleanup
+		exit
+	fi
+}
+
+_resume_writes()
+{
+	$DMSETUP_PROG suspend flakey-test
+	if [ $? -ne 0 ]; then
+		echo "failed to suspend flakey-test"
+		_unmount_flakey
+		_cleanup
+		exit
+	fi
+	$DMSETUP_PROG load flakey-test --table "0 $BLK_DEV_SIZE flakey $SCRATCH_DEV 0 180 0"
+	if [ $? -ne 0 ]; then
+		echo "failed to load table into flakey-test"
+		_unmount_flakey
+		_cleanup
+		exit
+	fi
+	$DMSETUP_PROG resume flakey-test
+	if [ $? -ne 0 ]; then
+		echo "failed to resumeflakey-test"
+		_unmount_flakey
+		_cleanup
+		exit
+	fi
+}
+
+_run_test()
+{
+	test_num=$1
+	extra=""
+
+	[ $2 -eq 1 ] && extra="-d"
+
+	$here/src/fsync-tester -s $SEED -r -t $test_num $extra $testfile
+	if [ $? -ne 0 ]; then
+		_unmount_flakey
+		_cleanup
+		exit
+	fi
+
+	_md5_checksum $testfile
+	_drop_writes
+	_unmount_flakey
+
+	#Ok mount so that any recovery that needs to happen is done
+	_resume_writes
+	_mount_flakey
+	_md5_checksum $testfile
+
+	#Unmount and fsck to make sure we got a valid fs after replay
+	_unmount_flakey
+	_check_scratch_fs
+	if [ $? -ne 0 ]; then
+		echo "fs inconsistent"
+		_cleanup
+		exit
+	fi
+	_mount_flakey
+}
+
+_scratch_mkfs >> $seqres.full 2>&1
+
+# Create a basic flakey device that will never error out
+$DMSETUP_PROG create flakey-test --table "0 $BLK_DEV_SIZE flakey $SCRATCH_DEV 0 180 0"
+if [ $? -ne 0 ]; then
+	echo "failed to create flakey device"
+	status=1
+	exit
+fi
+
+_mount_flakey
+
+for i in $(seq 1 20); do
+	echo "Running test $i buffered"
+	_run_test $i 0
+	echo "Running test $i direct"
+	_run_test $i 1
+done
+
+_cleanup
+status=0
+exit
diff --git a/tests/generic/311.out b/tests/generic/311.out
new file mode 100644
index 0000000..e443464
--- /dev/null
+++ b/tests/generic/311.out
@@ -0,0 +1,193 @@ 
+QA output created by 311
+Running test 1 buffered
+Random seed is 1
+ee6103415276cde95544b11b2675f132
+ee6103415276cde95544b11b2675f132
+Running test 1 direct
+Random seed is 1
+ee6103415276cde95544b11b2675f132
+ee6103415276cde95544b11b2675f132
+Running test 2 buffered
+Random seed is 1
+6ec7dd6da414514b832d9a8fc9098a06
+6ec7dd6da414514b832d9a8fc9098a06
+Running test 2 direct
+Random seed is 1
+6ec7dd6da414514b832d9a8fc9098a06
+6ec7dd6da414514b832d9a8fc9098a06
+Running test 3 buffered
+Random seed is 1
+Size is 1924, blocks is 962
+c80ba7f17988006f10bdc488efa9b372
+c80ba7f17988006f10bdc488efa9b372
+Running test 3 direct
+Random seed is 1
+Size is 1924, blocks is 962
+c80ba7f17988006f10bdc488efa9b372
+c80ba7f17988006f10bdc488efa9b372
+Running test 4 buffered
+Random seed is 1
+Size is 1924, blocks is 962
+c5f2b19e14d0f3e6755cac2986b8366d
+c5f2b19e14d0f3e6755cac2986b8366d
+Running test 4 direct
+Random seed is 1
+Size is 1924, blocks is 962
+c5f2b19e14d0f3e6755cac2986b8366d
+c5f2b19e14d0f3e6755cac2986b8366d
+Running test 5 buffered
+Random seed is 1
+Size is 1924, blocks is 962
+c80ba7f17988006f10bdc488efa9b372
+c80ba7f17988006f10bdc488efa9b372
+Running test 5 direct
+Random seed is 1
+Size is 1924, blocks is 962
+c80ba7f17988006f10bdc488efa9b372
+c80ba7f17988006f10bdc488efa9b372
+Running test 6 buffered
+Random seed is 1
+Size is 1924, blocks is 962
+c5f2b19e14d0f3e6755cac2986b8366d
+c5f2b19e14d0f3e6755cac2986b8366d
+Running test 6 direct
+Random seed is 1
+Size is 1924, blocks is 962
+c5f2b19e14d0f3e6755cac2986b8366d
+c5f2b19e14d0f3e6755cac2986b8366d
+Running test 7 buffered
+Random seed is 1
+Size is 1924, blocks is 962
+c80ba7f17988006f10bdc488efa9b372
+c80ba7f17988006f10bdc488efa9b372
+Running test 7 direct
+Random seed is 1
+Size is 1924, blocks is 962
+c80ba7f17988006f10bdc488efa9b372
+c80ba7f17988006f10bdc488efa9b372
+Running test 8 buffered
+Random seed is 1
+Size is 1924, blocks is 962
+c5f2b19e14d0f3e6755cac2986b8366d
+c5f2b19e14d0f3e6755cac2986b8366d
+Running test 8 direct
+Random seed is 1
+Size is 1924, blocks is 962
+c5f2b19e14d0f3e6755cac2986b8366d
+c5f2b19e14d0f3e6755cac2986b8366d
+Running test 9 buffered
+Random seed is 1
+Size is 1924, blocks is 962
+c80ba7f17988006f10bdc488efa9b372
+c80ba7f17988006f10bdc488efa9b372
+Running test 9 direct
+Random seed is 1
+Size is 1924, blocks is 962
+c80ba7f17988006f10bdc488efa9b372
+c80ba7f17988006f10bdc488efa9b372
+Running test 10 buffered
+Random seed is 1
+Size is 1924, blocks is 962
+c5f2b19e14d0f3e6755cac2986b8366d
+c5f2b19e14d0f3e6755cac2986b8366d
+Running test 10 direct
+Random seed is 1
+Size is 1924, blocks is 962
+c5f2b19e14d0f3e6755cac2986b8366d
+c5f2b19e14d0f3e6755cac2986b8366d
+Running test 11 buffered
+Random seed is 1
+Size is 1924, blocks is 962
+c80ba7f17988006f10bdc488efa9b372
+c80ba7f17988006f10bdc488efa9b372
+Running test 11 direct
+Random seed is 1
+Size is 1924, blocks is 962
+c80ba7f17988006f10bdc488efa9b372
+c80ba7f17988006f10bdc488efa9b372
+Running test 12 buffered
+Random seed is 1
+Size is 1924, blocks is 962
+c80ba7f17988006f10bdc488efa9b372
+c80ba7f17988006f10bdc488efa9b372
+Running test 12 direct
+Random seed is 1
+Size is 1924, blocks is 962
+c80ba7f17988006f10bdc488efa9b372
+c80ba7f17988006f10bdc488efa9b372
+Running test 13 buffered
+Random seed is 1
+Size is 1924, blocks is 962
+c80ba7f17988006f10bdc488efa9b372
+c80ba7f17988006f10bdc488efa9b372
+Running test 13 direct
+Random seed is 1
+Size is 1924, blocks is 962
+c80ba7f17988006f10bdc488efa9b372
+c80ba7f17988006f10bdc488efa9b372
+Running test 14 buffered
+Random seed is 1
+Size is 1924, blocks is 962
+c80ba7f17988006f10bdc488efa9b372
+c80ba7f17988006f10bdc488efa9b372
+Running test 14 direct
+Random seed is 1
+Size is 1924, blocks is 962
+c80ba7f17988006f10bdc488efa9b372
+c80ba7f17988006f10bdc488efa9b372
+Running test 15 buffered
+Random seed is 1
+Size is 1924, blocks is 962
+c5f2b19e14d0f3e6755cac2986b8366d
+c5f2b19e14d0f3e6755cac2986b8366d
+Running test 15 direct
+Random seed is 1
+Size is 1924, blocks is 962
+c5f2b19e14d0f3e6755cac2986b8366d
+c5f2b19e14d0f3e6755cac2986b8366d
+Running test 16 buffered
+Random seed is 1
+Size is 1924, blocks is 962
+c5f2b19e14d0f3e6755cac2986b8366d
+c5f2b19e14d0f3e6755cac2986b8366d
+Running test 16 direct
+Random seed is 1
+Size is 1924, blocks is 962
+c5f2b19e14d0f3e6755cac2986b8366d
+c5f2b19e14d0f3e6755cac2986b8366d
+Running test 17 buffered
+Random seed is 1
+Size is 1924, blocks is 962
+c5f2b19e14d0f3e6755cac2986b8366d
+c5f2b19e14d0f3e6755cac2986b8366d
+Running test 17 direct
+Random seed is 1
+Size is 1924, blocks is 962
+c5f2b19e14d0f3e6755cac2986b8366d
+c5f2b19e14d0f3e6755cac2986b8366d
+Running test 18 buffered
+Random seed is 1
+Size is 1924, blocks is 962
+c5f2b19e14d0f3e6755cac2986b8366d
+c5f2b19e14d0f3e6755cac2986b8366d
+Running test 18 direct
+Random seed is 1
+Size is 1924, blocks is 962
+c5f2b19e14d0f3e6755cac2986b8366d
+c5f2b19e14d0f3e6755cac2986b8366d
+Running test 19 buffered
+Random seed is 1
+9cc0323438bb10f5cc88cfbd5aaf5cfa
+9cc0323438bb10f5cc88cfbd5aaf5cfa
+Running test 19 direct
+Random seed is 1
+d41d8cd98f00b204e9800998ecf8427e
+d41d8cd98f00b204e9800998ecf8427e
+Running test 20 buffered
+Random seed is 1
+764e24deb80dc89aaecdadce4a656052
+764e24deb80dc89aaecdadce4a656052
+Running test 20 direct
+Random seed is 1
+764e24deb80dc89aaecdadce4a656052
+764e24deb80dc89aaecdadce4a656052
diff --git a/tests/generic/group b/tests/generic/group
index eb52833..a0830c1 100644
--- a/tests/generic/group
+++ b/tests/generic/group
@@ -113,3 +113,4 @@ 
 308 auto quick
 309 auto quick
 310 auto
+311 auto