openstack/cinder
Code Issues Proposed changes

Make sure device support Direct before setting

Browse Source 
We added '-t none' option to the qemu-img convert operation
in image_utils.py a while back to accomodate a couple of
backend devices that didn't flush writes on disconnect.
(Change: I7a04f683add8c23b9125fe837c4048ccc3ac224d)

The only problem here is that some backend devices don't
support Direct mode and raise an exception and fail when
setting this option.

This patch adds a simple check using dd to see if the dest
supports the Direct flag and only sets '-t none' if the device
does in fact support it.

Additionally it was brought up that even yet other backends
are using file devices not blk devices.  In their case setting
Direct will still work, however it's sub-optimal as qemu-convert
has internal mechanisms to make sure flushing etc are done
correctly and efficiently for those devices.  So to accomodate
that particular use case I'm also adding a check if blk dev
that can be used for determining whether to set Direct for the
qemu-convert process.

Change-Id: I34127ac373ceadcfb6fc2662628b1a91eb7b0046
Closes-Bug: 1375487
(cherry picked from commit c42273fbc1)
This commit is contained in:
John Griffith 2014-10-07 11:49:58 -06:00
parent bb7321c8a3
commit aaecfcf15e
6 changed files with 104 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
cinder/image/image_utils.py
View File

@ -63,13 +63,28 @@ def qemu_img_info(path):
def convert_image(source, dest, out_format, bps_limit=None):
"""Convert image to other format."""
start_time = timeutils.utcnow()
# Always set -t none. First it is needed for cgroup io/limiting
# and it is needed to ensure that all data hit the device before
# it gets unmapped remotely from the host
cmd = ('qemu-img', 'convert',
'-t', 'none',
'-O', out_format, source, dest)
# Check whether O_DIRECT is supported and set '-t none' if it is
# This is needed to ensure that all data hit the device before
# it gets unmapped remotely from the host for some backends
# Reference Bug: #1363016
# NOTE(jdg): In the case of file devices qemu does the
# flush properly and more efficiently than would be done
# setting O_DIRECT, so check for that and skip the
# setting for non BLK devs
if (utils.is_blk_device(dest) and
volume_utils.check_for_odirect_support(source,
dest,
'oflag=direct')):
cmd = ('qemu-img', 'convert',
'-t', 'none',
'-O', out_format, source, dest)
start_time = timeutils.utcnow()
cgcmd = volume_utils.setup_blkio_cgroup(source, dest, bps_limit)
if cgcmd:
cmd = tuple(cgcmd) + cmd

54
cinder/tests/test_image_utils.py
View File

@ -84,11 +84,16 @@ class TestUtils(test.TestCase):
mox = self._mox
mox.StubOutWithMock(utils, 'execute')
mox.StubOutWithMock(utils, 'is_blk_device')
TEST_OUT_FORMAT = 'vmdk'
TEST_SOURCE = 'img/qemu.img'
TEST_DEST = '/img/vmware.vmdk'
utils.is_blk_device(TEST_DEST).AndReturn(True)
utils.execute('dd', 'count=0', 'if=img/qemu.img',
'of=/img/vmware.vmdk', 'oflag=direct',
run_as_root=True)
utils.execute(
'qemu-img', 'convert', '-t', 'none', '-O', TEST_OUT_FORMAT,
TEST_SOURCE, TEST_DEST, run_as_root=True)
@ -207,12 +212,14 @@ class TestUtils(test.TestCase):
mox.StubOutWithMock(utils, 'execute')
mox.StubOutWithMock(image_utils, 'fetch')
mox.StubOutWithMock(volume_utils, 'setup_blkio_cgroup')
mox.StubOutWithMock(utils, 'is_blk_device')
TEST_INFO = ("image: qemu.qcow2\n"
"file format: raw\n"
"virtual size: 0 (0 bytes)\n"
"disk size: 0")
utils.is_blk_device(self.TEST_DEV_PATH).AndReturn(True)
CONF.set_override('volume_copy_bps_limit', bps_limit)
image_utils.create_temporary_file().AndReturn(self.TEST_DEV_PATH)
@ -239,6 +246,11 @@ class TestUtils(test.TestCase):
prefix = ('cgexec', '-g', 'blkio:test')
else:
prefix = ()
utils.execute('dd', 'count=0', 'if=/dev/ether/fake_dev',
'of=/dev/ether/fake_dev', 'oflag=direct',
run_as_root=True)
cmd = prefix + ('qemu-img', 'convert', '-t', 'none', '-O', 'raw',
self.TEST_DEV_PATH, self.TEST_DEV_PATH)
@ -306,8 +318,6 @@ class TestUtils(test.TestCase):
self.TEST_IMAGE_ID, self.TEST_DEV_PATH,
mox.IgnoreArg())
self._mox.VerifyAll()
def test_fetch_to_raw_on_error_parsing_failed(self):
SRC_INFO_NO_FORMAT = ("image: qemu.qcow2\n"
"virtual_size: 50M (52428800 bytes)\n"
@ -321,7 +331,6 @@ class TestUtils(test.TestCase):
context, self._image_service,
self.TEST_IMAGE_ID, self.TEST_DEV_PATH,
mox.IgnoreArg())
self._mox.VerifyAll()
def test_fetch_to_raw_on_error_backing_file(self):
SRC_INFO_BACKING_FILE = ("image: qemu.qcow2\n"
@ -338,7 +347,6 @@ class TestUtils(test.TestCase):
context, self._image_service,
self.TEST_IMAGE_ID, self.TEST_DEV_PATH,
mox.IgnoreArg())
self._mox.VerifyAll()
@mock.patch('os.stat')
def test_fetch_to_raw_on_error_not_convert_to_raw(self, mock_stat):
@ -443,7 +451,8 @@ class TestUtils(test.TestCase):
prefix = ('cgexec', '-g', 'blkio:test')
else:
prefix = ()
cmd = prefix + ('qemu-img', 'convert', '-t', 'none', '-O', 'qcow2',
cmd = prefix + ('qemu-img', 'convert', '-O', 'qcow2',
mox.IgnoreArg(), mox.IgnoreArg())
m = self._mox
@ -452,6 +461,7 @@ class TestUtils(test.TestCase):
volume_utils.setup_blkio_cgroup(mox.IgnoreArg(), mox.IgnoreArg(),
bps_limit).AndReturn(prefix)
utils.execute(*cmd, run_as_root=True)
utils.execute(
'env', 'LC_ALL=C', 'qemu-img', 'info',
@ -466,8 +476,37 @@ class TestUtils(test.TestCase):
@mock.patch('os.stat')
def test_upload_volume_with_bps_limit(self, mock_stat):
bps_limit = 1048576
image_meta = {'id': 1, 'disk_format': 'qcow2'}
TEST_RET = "image: qemu.qcow2\n"\
"file_format: qcow2 \n"\
"virtual_size: 50M (52428800 bytes)\n"\
"cluster_size: 65536\n"\
"disk_size: 196K (200704 bytes)"
self.test_upload_volume(bps_limit=1048576)
CONF.set_override('volume_copy_bps_limit', bps_limit)
prefix = ('cgexec', '-g', 'blkio:test')
cmd = prefix + ('qemu-img', 'convert', '-O', 'qcow2',
mox.IgnoreArg(), mox.IgnoreArg())
m = self._mox
m.StubOutWithMock(utils, 'execute')
m.StubOutWithMock(volume_utils, 'setup_blkio_cgroup')
m.StubOutWithMock(volume_utils, 'check_for_odirect_support')
volume_utils.setup_blkio_cgroup(mox.IgnoreArg(), mox.IgnoreArg(),
bps_limit).AndReturn(prefix)
utils.execute(*cmd, run_as_root=True)
utils.execute(
'env', 'LC_ALL=C', 'qemu-img', 'info',
mox.IgnoreArg(), run_as_root=True).AndReturn(
(TEST_RET, 'ignored'))
m.ReplayAll()
image_utils.upload_volume(context, FakeImageService(),
image_meta, '/dev/loop1')
m.VerifyAll()
def test_upload_volume_with_raw_image(self):
image_meta = {'id': 1, 'disk_format': 'raw'}
@ -493,8 +532,9 @@ class TestUtils(test.TestCase):
m = self._mox
m.StubOutWithMock(utils, 'execute')
m.StubOutWithMock(volume_utils, 'check_for_odirect_support')
utils.execute('qemu-img', 'convert', '-t', 'none', '-O', 'qcow2',
utils.execute('qemu-img', 'convert', '-O', 'qcow2',
mox.IgnoreArg(), mox.IgnoreArg(), run_as_root=True)
utils.execute(
'env', 'LC_ALL=C', 'qemu-img', 'info',

4
cinder/tests/test_volume.py
View File

@ -920,6 +920,9 @@ class VolumeTestCase(BaseVolumeTestCase):
return inner_sync2
return inner_sync1
def _fake_execute(self, *cmd, **kwargs):
pass
def test_create_volume_from_snapshot_check_locks(self):
# mock the synchroniser so we can record events
self.stubs.Set(utils, 'synchronized', self._mock_synchronized)
@ -989,6 +992,7 @@ class VolumeTestCase(BaseVolumeTestCase):
def test_create_volume_from_volume_check_locks(self):
# mock the synchroniser so we can record events
self.stubs.Set(utils, 'synchronized', self._mock_synchronized)
self.stubs.Set(utils, 'execute', self._fake_execute)
orig_flow = engine.ActionEngine.run

7
cinder/tests/test_volume_utils.py
View File

@ -213,6 +213,13 @@ class CopyVolumeTestCase(test.TestCase):
if 'iflag=direct' in cmd and 'oflag=direct' in cmd:
raise exception.InvalidInput(message='iflag/oflag error')
def fake_check_odirect(src, dest, flags='blah'):
return False
self.stubs.Set(volume_utils,
'check_for_odirect_support',
fake_check_odirect)
volume_utils.copy_volume('/dev/zero', '/dev/null', 1024,
CONF.volume_dd_blocksize, sync=True,
ionice=None, execute=fake_utils_execute)

10
cinder/utils.py
View File

@ -757,3 +757,13 @@ def remove_invalid_filter_options(context, filters,
LOG.debug(log_msg)
for opt in unknown_options:
del filters[opt]
def is_blk_device(dev):
try:
if stat.S_ISBLK(os.stat(dev).st_mode):
return True
return False
except Exception:
LOG.debug('Path %s not found in is_blk_device check' % dev)
return False

24
cinder/volume/utils.py
View File

@ -285,18 +285,26 @@ def _calculate_count(size_in_m, blocksize):
return blocksize, int(count)
def check_for_odirect_support(src, dest, flag='oflag=direct'):
# Check whether O_DIRECT is supported
try:
utils.execute('dd', 'count=0', 'if=%s' % src, 'of=%s' % dest,
flag, run_as_root=True)
return True
except processutils.ProcessExecutionError:
return False
def copy_volume(srcstr, deststr, size_in_m, blocksize, sync=False,
execute=utils.execute, ionice=None):
# Use O_DIRECT to avoid thrashing the system buffer cache
extra_flags = []
# Check whether O_DIRECT is supported to iflag and oflag separately
for flag in ['iflag=direct', 'oflag=direct']:
try:
execute('dd', 'count=0', 'if=%s' % srcstr, 'of=%s' % deststr,
flag, run_as_root=True)
extra_flags.append(flag)
except processutils.ProcessExecutionError:
pass
if check_for_odirect_support(srcstr, deststr, 'iflag=direct'):
extra_flags.append('iflag=direct')
if check_for_odirect_support(srcstr, deststr, 'oflag=direct'):
extra_flags.append('oflag=direct')
# If the volume is being unprovisioned then
# request the data is persisted before returning,