diff mbox series

[v3] generic: test truncating mixed written/unwritten XFS realtime extent

Message ID 110dbf3ff8c8004e4eecef2cc2e84dfe2d3ddd9f.1575416911.git.osandov@fb.com (mailing list archive)
State New, archived
Headers show
Series [v3] generic: test truncating mixed written/unwritten XFS realtime extent | expand

Commit Message

Omar Sandoval Dec. 3, 2019, 11:51 p.m. UTC
From: Omar Sandoval <osandov@fb.com>

The only XFS-specific part of this test is the setup, so we can make the
rest a generic test. It's slow, though, as it needs to write 8GB to
convert a big unwritten extent to written.

Signed-off-by: Omar Sandoval <osandov@fb.com>
---
Changes from v2 -> v3:

- Use _create_loop_device and _destroy_loop_device instead of losetup

Changes from v1 -> v2:

- If rtdev is not configured, fall back to loop device on test
  filesystem
- Use XFS_IO_PROG instead of fallocate/sync/dd
- Use truncate instead of rm
- Add comments explaining the steps

 tests/generic/589     | 100 ++++++++++++++++++++++++++++++++++++++++++
 tests/generic/589.out |   2 +
 tests/generic/group   |   1 +
 3 files changed, 103 insertions(+)
 create mode 100755 tests/generic/589
 create mode 100644 tests/generic/589.out

Comments

Darrick J. Wong Dec. 4, 2019, 12:12 a.m. UTC | #1
On Tue, Dec 03, 2019 at 03:51:52PM -0800, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
> 
> The only XFS-specific part of this test is the setup, so we can make the
> rest a generic test. It's slow, though, as it needs to write 8GB to
> convert a big unwritten extent to written.
> 
> Signed-off-by: Omar Sandoval <osandov@fb.com>

Looks good to me,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> ---
> Changes from v2 -> v3:
> 
> - Use _create_loop_device and _destroy_loop_device instead of losetup
> 
> Changes from v1 -> v2:
> 
> - If rtdev is not configured, fall back to loop device on test
>   filesystem
> - Use XFS_IO_PROG instead of fallocate/sync/dd
> - Use truncate instead of rm
> - Add comments explaining the steps
> 
>  tests/generic/589     | 100 ++++++++++++++++++++++++++++++++++++++++++
>  tests/generic/589.out |   2 +
>  tests/generic/group   |   1 +
>  3 files changed, 103 insertions(+)
>  create mode 100755 tests/generic/589
>  create mode 100644 tests/generic/589.out
> 
> diff --git a/tests/generic/589 b/tests/generic/589
> new file mode 100755
> index 00000000..aab37bb4
> --- /dev/null
> +++ b/tests/generic/589
> @@ -0,0 +1,100 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2019 Facebook.  All Rights Reserved.
> +#
> +# FS QA Test 589
> +#
> +# Test "xfs: fix realtime file data space leak" and "xfs: don't check for AG
> +# deadlock for realtime files in bunmapi". On XFS without the fix, truncate
> +# will hang forever. On other filesystems, this just tests writing into big
> +# fallocates.
> +#
> +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.*
> +	test -n "$loop" && _destroy_loop_device "$loop"
> +	rm -f "$TEST_DIR/$seq"
> +}
> +
> +. ./common/rc
> +. ./common/filter
> +
> +rm -f $seqres.full
> +
> +_supported_fs generic
> +_supported_os Linux
> +_require_scratch_nocheck
> +
> +maxextlen=$((0x1fffff))
> +bs=4096
> +rextsize=4
> +filesz=$(((maxextlen + 1) * bs))
> +
> +extra_options=""
> +# If we're testing XFS, set up the realtime device to reproduce the bug.
> +if [[ $FSTYP = xfs ]]; then
> +	# If we don't have a realtime device, set up a loop device on the test
> +	# filesystem.
> +	if [[ $USE_EXTERNAL != yes || -z $SCRATCH_RTDEV ]]; then
> +		_require_test
> +		loopsz="$((filesz + (1 << 26)))"
> +		_require_fs_space "$TEST_DIR" $((loopsz / 1024))
> +		$XFS_IO_PROG -c "truncate $loopsz" -f "$TEST_DIR/$seq"
> +		loop="$(_create_loop_device "$TEST_DIR/$seq")"
> +		USE_EXTERNAL=yes
> +		SCRATCH_RTDEV="$loop"
> +	fi
> +	extra_options="$extra_options -bsize=$bs"
> +	extra_options="$extra_options -r extsize=$((bs * rextsize))"
> +	extra_options="$extra_options -d agsize=$(((maxextlen + 1) * bs / 2)),rtinherit=1"
> +fi
> +_scratch_mkfs $extra_options >>$seqres.full 2>&1
> +_scratch_mount
> +_require_fs_space "$SCRATCH_MNT" $((filesz / 1024))
> +
> +# Allocate maxextlen + 1 blocks. As long as the allocator does something sane,
> +# we should end up with two extents that look something like:
> +#
> +# u3.bmx[0-1] = [startoff,startblock,blockcount,extentflag]
> +# 0:[0,0,2097148,1]
> +# 1:[2097148,2097148,4,1]
> +#
> +# Extent 0 has blockcount = ALIGN_DOWN(maxextlen, rextsize). Extent 1 is
> +# adjacent and has blockcount = rextsize. Both are unwritten.
> +$XFS_IO_PROG -c "falloc 0 $filesz" -c fsync -f "$SCRATCH_MNT/file"
> +
> +# Write extent 0 + one block of extent 1. Our extents should end up like so:
> +#
> +# u3.bmx[0-1] = [startoff,startblock,blockcount,extentflag]
> +# 0:[0,0,2097149,0]
> +# 1:[2097149,2097149,3,1]
> +#
> +# Extent 0 is written and has blockcount = ALIGN_DOWN(maxextlen, rextsize) + 1,
> +# Extent 1 is adjacent, unwritten, and has blockcount = rextsize - 1 and
> +# startblock % rextsize = 1.
> +#
> +# The -b is just to speed things up (doing GBs of I/O in 4k chunks kind of
> +# sucks).
> +$XFS_IO_PROG -c "pwrite -b 1M -W 0 $(((maxextlen + 2 - rextsize) * bs))" \
> +	"$SCRATCH_MNT/file" >> "$seqres.full"
> +
> +# Truncate the extents.
> +$XFS_IO_PROG -c "truncate 0" -c fsync "$SCRATCH_MNT/file"
> +
> +# We need to do this before the loop device gets torn down.
> +_scratch_unmount
> +_check_scratch_fs
> +
> +echo "Silence is golden"
> +status=0
> +exit
> diff --git a/tests/generic/589.out b/tests/generic/589.out
> new file mode 100644
> index 00000000..5ab6ab10
> --- /dev/null
> +++ b/tests/generic/589.out
> @@ -0,0 +1,2 @@
> +QA output created by 589
> +Silence is golden
> diff --git a/tests/generic/group b/tests/generic/group
> index 87d7441c..be6f4a43 100644
> --- a/tests/generic/group
> +++ b/tests/generic/group
> @@ -591,3 +591,4 @@
>  586 auto quick rw prealloc
>  587 auto quick rw prealloc
>  588 auto quick log clone
> +589 auto prealloc preallocrw dangerous
> -- 
> 2.24.0
>
Eryu Guan Dec. 8, 2019, 3:43 p.m. UTC | #2
On Tue, Dec 03, 2019 at 03:51:52PM -0800, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
> 
> The only XFS-specific part of this test is the setup, so we can make the
> rest a generic test. It's slow, though, as it needs to write 8GB to
> convert a big unwritten extent to written.
> 
> Signed-off-by: Omar Sandoval <osandov@fb.com>
> ---
> Changes from v2 -> v3:
> 
> - Use _create_loop_device and _destroy_loop_device instead of losetup
> 
> Changes from v1 -> v2:
> 
> - If rtdev is not configured, fall back to loop device on test
>   filesystem
> - Use XFS_IO_PROG instead of fallocate/sync/dd
> - Use truncate instead of rm
> - Add comments explaining the steps
> 
>  tests/generic/589     | 100 ++++++++++++++++++++++++++++++++++++++++++
>  tests/generic/589.out |   2 +
>  tests/generic/group   |   1 +
>  3 files changed, 103 insertions(+)
>  create mode 100755 tests/generic/589
>  create mode 100644 tests/generic/589.out
> 
> diff --git a/tests/generic/589 b/tests/generic/589
> new file mode 100755
> index 00000000..aab37bb4
> --- /dev/null
> +++ b/tests/generic/589
> @@ -0,0 +1,100 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2019 Facebook.  All Rights Reserved.
> +#
> +# FS QA Test 589
> +#
> +# Test "xfs: fix realtime file data space leak" and "xfs: don't check for AG
> +# deadlock for realtime files in bunmapi". On XFS without the fix, truncate
> +# will hang forever. On other filesystems, this just tests writing into big
> +# fallocates.
> +#
> +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 $tmp.*
> +	test -n "$loop" && _destroy_loop_device "$loop"
> +	rm -f "$TEST_DIR/$seq"
> +}
> +
> +. ./common/rc
> +. ./common/filter
> +
> +rm -f $seqres.full
> +
> +_supported_fs generic
> +_supported_os Linux
> +_require_scratch_nocheck
> +
> +maxextlen=$((0x1fffff))
> +bs=4096
> +rextsize=4
> +filesz=$(((maxextlen + 1) * bs))
> +
> +extra_options=""
> +# If we're testing XFS, set up the realtime device to reproduce the bug.
> +if [[ $FSTYP = xfs ]]; then
> +	# If we don't have a realtime device, set up a loop device on the test
> +	# filesystem.
> +	if [[ $USE_EXTERNAL != yes || -z $SCRATCH_RTDEV ]]; then
> +		_require_test
> +		loopsz="$((filesz + (1 << 26)))"
> +		_require_fs_space "$TEST_DIR" $((loopsz / 1024))
> +		$XFS_IO_PROG -c "truncate $loopsz" -f "$TEST_DIR/$seq"
> +		loop="$(_create_loop_device "$TEST_DIR/$seq")"
> +		USE_EXTERNAL=yes
> +		SCRATCH_RTDEV="$loop"
> +	fi
> +	extra_options="$extra_options -bsize=$bs"
> +	extra_options="$extra_options -r extsize=$((bs * rextsize))"
> +	extra_options="$extra_options -d agsize=$(((maxextlen + 1) * bs / 2)),rtinherit=1"

reflink is enabled by default since xfsprogs v5.1.0, and this causes
_scratch_mkfs to fail as "reflink not supported with realtime devices",
so I added a check here

	if _scratch_mkfs_xfs_supported -m reflink=0 >/dev/null 2>&1; then
		extra_options="$extra_options -m reflink=0"
	fi

Thanks,
Eryu

> +_scratch_mount
> +_require_fs_space "$SCRATCH_MNT" $((filesz / 1024))
> +
> +# Allocate maxextlen + 1 blocks. As long as the allocator does something sane,
> +# we should end up with two extents that look something like:
> +#
> +# u3.bmx[0-1] = [startoff,startblock,blockcount,extentflag]
> +# 0:[0,0,2097148,1]
> +# 1:[2097148,2097148,4,1]
> +#
> +# Extent 0 has blockcount = ALIGN_DOWN(maxextlen, rextsize). Extent 1 is
> +# adjacent and has blockcount = rextsize. Both are unwritten.
> +$XFS_IO_PROG -c "falloc 0 $filesz" -c fsync -f "$SCRATCH_MNT/file"
> +
> +# Write extent 0 + one block of extent 1. Our extents should end up like so:
> +#
> +# u3.bmx[0-1] = [startoff,startblock,blockcount,extentflag]
> +# 0:[0,0,2097149,0]
> +# 1:[2097149,2097149,3,1]
> +#
> +# Extent 0 is written and has blockcount = ALIGN_DOWN(maxextlen, rextsize) + 1,
> +# Extent 1 is adjacent, unwritten, and has blockcount = rextsize - 1 and
> +# startblock % rextsize = 1.
> +#
> +# The -b is just to speed things up (doing GBs of I/O in 4k chunks kind of
> +# sucks).
> +$XFS_IO_PROG -c "pwrite -b 1M -W 0 $(((maxextlen + 2 - rextsize) * bs))" \
> +	"$SCRATCH_MNT/file" >> "$seqres.full"
> +
> +# Truncate the extents.
> +$XFS_IO_PROG -c "truncate 0" -c fsync "$SCRATCH_MNT/file"
> +
> +# We need to do this before the loop device gets torn down.
> +_scratch_unmount
> +_check_scratch_fs
> +
> +echo "Silence is golden"
> +status=0
> +exit
> diff --git a/tests/generic/589.out b/tests/generic/589.out
> new file mode 100644
> index 00000000..5ab6ab10
> --- /dev/null
> +++ b/tests/generic/589.out
> @@ -0,0 +1,2 @@
> +QA output created by 589
> +Silence is golden
> diff --git a/tests/generic/group b/tests/generic/group
> index 87d7441c..be6f4a43 100644
> --- a/tests/generic/group
> +++ b/tests/generic/group
> @@ -591,3 +591,4 @@
>  586 auto quick rw prealloc
>  587 auto quick rw prealloc
>  588 auto quick log clone
> +589 auto prealloc preallocrw dangerous
> -- 
> 2.24.0
>
Eryu Guan Dec. 8, 2019, 5:04 p.m. UTC | #3
On Tue, Dec 03, 2019 at 03:51:52PM -0800, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
> 
> The only XFS-specific part of this test is the setup, so we can make the
> rest a generic test. It's slow, though, as it needs to write 8GB to
> convert a big unwritten extent to written.
> 
> Signed-off-by: Omar Sandoval <osandov@fb.com>
> ---
> Changes from v2 -> v3:
> 
> - Use _create_loop_device and _destroy_loop_device instead of losetup
> 
> Changes from v1 -> v2:
> 
> - If rtdev is not configured, fall back to loop device on test
>   filesystem
> - Use XFS_IO_PROG instead of fallocate/sync/dd
> - Use truncate instead of rm
> - Add comments explaining the steps
> 
>  tests/generic/589     | 100 ++++++++++++++++++++++++++++++++++++++++++
>  tests/generic/589.out |   2 +
>  tests/generic/group   |   1 +
>  3 files changed, 103 insertions(+)
>  create mode 100755 tests/generic/589
>  create mode 100644 tests/generic/589.out
> 
> diff --git a/tests/generic/589 b/tests/generic/589
> new file mode 100755
> index 00000000..aab37bb4
> --- /dev/null
> +++ b/tests/generic/589
> @@ -0,0 +1,100 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2019 Facebook.  All Rights Reserved.
> +#
> +# FS QA Test 589
> +#
> +# Test "xfs: fix realtime file data space leak" and "xfs: don't check for AG
> +# deadlock for realtime files in bunmapi". On XFS without the fix, truncate
> +# will hang forever. On other filesystems, this just tests writing into big
> +# fallocates.
> +#
> +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 $tmp.*
> +	test -n "$loop" && _destroy_loop_device "$loop"
> +	rm -f "$TEST_DIR/$seq"
> +}
> +
> +. ./common/rc
> +. ./common/filter
> +
> +rm -f $seqres.full
> +
> +_supported_fs generic
> +_supported_os Linux
> +_require_scratch_nocheck
> +
> +maxextlen=$((0x1fffff))
> +bs=4096
> +rextsize=4
> +filesz=$(((maxextlen + 1) * bs))
> +
> +extra_options=""
> +# If we're testing XFS, set up the realtime device to reproduce the bug.
> +if [[ $FSTYP = xfs ]]; then
> +	# If we don't have a realtime device, set up a loop device on the test
> +	# filesystem.
> +	if [[ $USE_EXTERNAL != yes || -z $SCRATCH_RTDEV ]]; then
> +		_require_test
> +		loopsz="$((filesz + (1 << 26)))"
> +		_require_fs_space "$TEST_DIR" $((loopsz / 1024))
> +		$XFS_IO_PROG -c "truncate $loopsz" -f "$TEST_DIR/$seq"
> +		loop="$(_create_loop_device "$TEST_DIR/$seq")"
> +		USE_EXTERNAL=yes
> +		SCRATCH_RTDEV="$loop"
> +	fi
> +	extra_options="$extra_options -bsize=$bs"
> +	extra_options="$extra_options -r extsize=$((bs * rextsize))"
> +	extra_options="$extra_options -d agsize=$(((maxextlen + 1) * bs / 2)),rtinherit=1"
> +fi
> +_scratch_mkfs $extra_options >>$seqres.full 2>&1
> +_scratch_mount
> +_require_fs_space "$SCRATCH_MNT" $((filesz / 1024))
> +
> +# Allocate maxextlen + 1 blocks. As long as the allocator does something sane,
> +# we should end up with two extents that look something like:
> +#
> +# u3.bmx[0-1] = [startoff,startblock,blockcount,extentflag]
> +# 0:[0,0,2097148,1]
> +# 1:[2097148,2097148,4,1]
> +#
> +# Extent 0 has blockcount = ALIGN_DOWN(maxextlen, rextsize). Extent 1 is
> +# adjacent and has blockcount = rextsize. Both are unwritten.
> +$XFS_IO_PROG -c "falloc 0 $filesz" -c fsync -f "$SCRATCH_MNT/file"
> +
> +# Write extent 0 + one block of extent 1. Our extents should end up like so:
> +#
> +# u3.bmx[0-1] = [startoff,startblock,blockcount,extentflag]
> +# 0:[0,0,2097149,0]
> +# 1:[2097149,2097149,3,1]
> +#
> +# Extent 0 is written and has blockcount = ALIGN_DOWN(maxextlen, rextsize) + 1,
> +# Extent 1 is adjacent, unwritten, and has blockcount = rextsize - 1 and
> +# startblock % rextsize = 1.
> +#
> +# The -b is just to speed things up (doing GBs of I/O in 4k chunks kind of
> +# sucks).
> +$XFS_IO_PROG -c "pwrite -b 1M -W 0 $(((maxextlen + 2 - rextsize) * bs))" \
> +	"$SCRATCH_MNT/file" >> "$seqres.full"
> +
> +# Truncate the extents.
> +$XFS_IO_PROG -c "truncate 0" -c fsync "$SCRATCH_MNT/file"
> +
> +# We need to do this before the loop device gets torn down.
> +_scratch_unmount
> +_check_scratch_fs
> +
> +echo "Silence is golden"
> +status=0
> +exit
> diff --git a/tests/generic/589.out b/tests/generic/589.out
> new file mode 100644
> index 00000000..5ab6ab10
> --- /dev/null
> +++ b/tests/generic/589.out
> @@ -0,0 +1,2 @@
> +QA output created by 589
> +Silence is golden
> diff --git a/tests/generic/group b/tests/generic/group
> index 87d7441c..be6f4a43 100644
> --- a/tests/generic/group
> +++ b/tests/generic/group
> @@ -591,3 +591,4 @@
>  586 auto quick rw prealloc
>  587 auto quick rw prealloc
>  588 auto quick log clone
> +589 auto prealloc preallocrw dangerous

Also, I noticed that the fixes are already in latest upstream kernel, so
I removed dangerous group as well.

Thanks,
Eryu

> -- 
> 2.24.0
>
diff mbox series

Patch

diff --git a/tests/generic/589 b/tests/generic/589
new file mode 100755
index 00000000..aab37bb4
--- /dev/null
+++ b/tests/generic/589
@@ -0,0 +1,100 @@ 
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2019 Facebook.  All Rights Reserved.
+#
+# FS QA Test 589
+#
+# Test "xfs: fix realtime file data space leak" and "xfs: don't check for AG
+# deadlock for realtime files in bunmapi". On XFS without the fix, truncate
+# will hang forever. On other filesystems, this just tests writing into big
+# fallocates.
+#
+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 $tmp.*
+	test -n "$loop" && _destroy_loop_device "$loop"
+	rm -f "$TEST_DIR/$seq"
+}
+
+. ./common/rc
+. ./common/filter
+
+rm -f $seqres.full
+
+_supported_fs generic
+_supported_os Linux
+_require_scratch_nocheck
+
+maxextlen=$((0x1fffff))
+bs=4096
+rextsize=4
+filesz=$(((maxextlen + 1) * bs))
+
+extra_options=""
+# If we're testing XFS, set up the realtime device to reproduce the bug.
+if [[ $FSTYP = xfs ]]; then
+	# If we don't have a realtime device, set up a loop device on the test
+	# filesystem.
+	if [[ $USE_EXTERNAL != yes || -z $SCRATCH_RTDEV ]]; then
+		_require_test
+		loopsz="$((filesz + (1 << 26)))"
+		_require_fs_space "$TEST_DIR" $((loopsz / 1024))
+		$XFS_IO_PROG -c "truncate $loopsz" -f "$TEST_DIR/$seq"
+		loop="$(_create_loop_device "$TEST_DIR/$seq")"
+		USE_EXTERNAL=yes
+		SCRATCH_RTDEV="$loop"
+	fi
+	extra_options="$extra_options -bsize=$bs"
+	extra_options="$extra_options -r extsize=$((bs * rextsize))"
+	extra_options="$extra_options -d agsize=$(((maxextlen + 1) * bs / 2)),rtinherit=1"
+fi
+_scratch_mkfs $extra_options >>$seqres.full 2>&1
+_scratch_mount
+_require_fs_space "$SCRATCH_MNT" $((filesz / 1024))
+
+# Allocate maxextlen + 1 blocks. As long as the allocator does something sane,
+# we should end up with two extents that look something like:
+#
+# u3.bmx[0-1] = [startoff,startblock,blockcount,extentflag]
+# 0:[0,0,2097148,1]
+# 1:[2097148,2097148,4,1]
+#
+# Extent 0 has blockcount = ALIGN_DOWN(maxextlen, rextsize). Extent 1 is
+# adjacent and has blockcount = rextsize. Both are unwritten.
+$XFS_IO_PROG -c "falloc 0 $filesz" -c fsync -f "$SCRATCH_MNT/file"
+
+# Write extent 0 + one block of extent 1. Our extents should end up like so:
+#
+# u3.bmx[0-1] = [startoff,startblock,blockcount,extentflag]
+# 0:[0,0,2097149,0]
+# 1:[2097149,2097149,3,1]
+#
+# Extent 0 is written and has blockcount = ALIGN_DOWN(maxextlen, rextsize) + 1,
+# Extent 1 is adjacent, unwritten, and has blockcount = rextsize - 1 and
+# startblock % rextsize = 1.
+#
+# The -b is just to speed things up (doing GBs of I/O in 4k chunks kind of
+# sucks).
+$XFS_IO_PROG -c "pwrite -b 1M -W 0 $(((maxextlen + 2 - rextsize) * bs))" \
+	"$SCRATCH_MNT/file" >> "$seqres.full"
+
+# Truncate the extents.
+$XFS_IO_PROG -c "truncate 0" -c fsync "$SCRATCH_MNT/file"
+
+# We need to do this before the loop device gets torn down.
+_scratch_unmount
+_check_scratch_fs
+
+echo "Silence is golden"
+status=0
+exit
diff --git a/tests/generic/589.out b/tests/generic/589.out
new file mode 100644
index 00000000..5ab6ab10
--- /dev/null
+++ b/tests/generic/589.out
@@ -0,0 +1,2 @@ 
+QA output created by 589
+Silence is golden
diff --git a/tests/generic/group b/tests/generic/group
index 87d7441c..be6f4a43 100644
--- a/tests/generic/group
+++ b/tests/generic/group
@@ -591,3 +591,4 @@ 
 586 auto quick rw prealloc
 587 auto quick rw prealloc
 588 auto quick log clone
+589 auto prealloc preallocrw dangerous