x/bareon
Code Issues Proposed changes

Make several attempts to attach image file

Browse Source 
If one starts 2 or more instances of fuel-agent simultaneously, then
fuel-agent could fail on loop device allocation. With this patch it
makes several attempts to attach temporary image file to loop device.

Change-Id: I502eb07a69a2d813157d7511fc03032671e98196
Closes-Bug: #1506071
This commit is contained in:
Andrey Tykhonov 2015-10-20 18:00:38 +03:00
parent 49e2e8a08a
commit 9e4b5ad8dc
5 changed files with 129 additions and 30 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

50
fuel_agent/manager.py
View File

@ -88,6 +88,11 @@ opts = [
# isn't theoretically present anymore.
help='Maximum allowed loop devices count to use'
),
cfg.IntOpt(
'max_allowed_attempts_attach_image',
default=10,
help='Maximum allowed attempts to attach image file to loop device'
),
cfg.IntOpt(
'sparse_file_size',
# XXX: Apparently Fuel configures the node root filesystem to span
@ -608,13 +613,12 @@ class Manager(object):
# to be able to shrink them and move in the end
image.img_tmp_file = img_tmp_file
LOG.debug('Looking for a free loop device')
image.target_device.name = bu.get_free_loop_device(
loop_device_major_number=CONF.loop_device_major_number,
max_loop_devices_count=CONF.max_loop_devices_count)
LOG.debug('Attaching temporary image file to free loop device')
bu.attach_file_to_loop(img_tmp_file, str(image.target_device))
image.target_device.name = \
bu.attach_file_to_free_loop_device(
img_tmp_file,
max_loop_devices_count=CONF.max_loop_devices_count,
loop_device_major_number=CONF.loop_device_major_number,
max_attempts=CONF.max_allowed_attempts_attach_image)
# find fs with the same loop device object
# as image.target_device
@ -794,22 +798,24 @@ class Manager(object):
LOG.debug('Finally: umounting chroot tree %s', chroot)
self.umount_target(chroot, pseudo=False)
for image in self.driver.image_scheme.images:
LOG.debug('Finally: detaching loop device: %s',
str(image.target_device))
try:
bu.deattach_loop(str(image.target_device))
except errors.ProcessExecutionError as e:
LOG.warning('Error occured while trying to detach '
'loop device %s. Error message: %s',
str(image.target_device), e)
if image.target_device.name:
LOG.debug('Finally: detaching loop device: %s',
image.target_device.name)
try:
bu.deattach_loop(image.target_device.name)
except errors.ProcessExecutionError as e:
LOG.warning('Error occured while trying to detach '
'loop device %s. Error message: %s',
image.target_device.name, e)
LOG.debug('Finally: removing temporary file: %s',
image.img_tmp_file)
try:
os.unlink(image.img_tmp_file)
except OSError:
LOG.debug('Finally: file %s seems does not exist '
'or can not be removed', image.img_tmp_file)
if image.img_tmp_file:
LOG.debug('Finally: removing temporary file: %s',
image.img_tmp_file)
try:
os.unlink(image.img_tmp_file)
except OSError:
LOG.debug('Finally: file %s seems does not exist '
'or can not be removed', image.img_tmp_file)
LOG.debug('Finally: removing chroot directory: %s', chroot)
try:
os.rmdir(chroot)

1
fuel_agent/objects/image.py
View File

@ -34,6 +34,7 @@ class Image(object):
self.container = container
self.size = size
self.md5 = md5
self.img_tmp_file = None
class ImageScheme(object):

44
fuel_agent/tests/test_build_utils.py
View File

@ -502,3 +502,47 @@ class BuildUtilsTestCase(unittest2.TestCase):
def test_containerize_bad_container(self):
self.assertRaises(errors.WrongImageDataError, bu.containerize, 'file',
'fake')
@mock.patch('fuel_agent.utils.build.get_free_loop_device')
@mock.patch('fuel_agent.utils.build.attach_file_to_loop')
def test_do_build_image_retries_attach_image_max_attempts_exceeded(
self, mock_attach_file, mock_get_free_loop_device):
mock_attach_file.side_effect = errors.ProcessExecutionError()
with self.assertRaises(errors.NoFreeLoopDevices):
bu.attach_file_to_free_loop_device(
mock.sentinel, max_loop_devices_count=255,
loop_device_major_number=7, max_attempts=3)
self.assertEqual(mock_attach_file.call_count, 3)
@mock.patch('fuel_agent.utils.build.get_free_loop_device')
@mock.patch('fuel_agent.utils.build.attach_file_to_loop')
def test_do_build_image_retries_attach_image(
self, mock_attach_file, mock_get_free_loop_device):
mock_attach_file.side_effect = \
[errors.ProcessExecutionError(),
errors.ProcessExecutionError(),
True]
free_loop_device = '/dev/loop0'
mock_get_free_loop_device.return_value = free_loop_device
loop_device_major_number = 7
max_loop_devices_count = 255
max_attempts = 3
filename = mock.sentinel
loop_device = bu.attach_file_to_free_loop_device(
filename, max_loop_devices_count=max_loop_devices_count,
loop_device_major_number=loop_device_major_number,
max_attempts=max_attempts)
self.assertEqual(free_loop_device, loop_device)
self.assertEqual(
[mock.call(loop_device_major_number=loop_device_major_number,
max_loop_devices_count=max_loop_devices_count)] * 3,
mock_get_free_loop_device.call_args_list)
self.assertEqual(
[mock.call(filename, '/dev/loop0')] * 3,
mock_attach_file.call_args_list)

22
fuel_agent/tests/test_manager.py
View File

@ -846,7 +846,8 @@ class TestImageBuild(unittest2.TestCase):
mock_os.path.basename.side_effect = ['img.img.gz', 'img-boot.img.gz']
mock_bu.create_sparse_tmp_file.side_effect = \
['/tmp/img', '/tmp/img-boot']
mock_bu.get_free_loop_device.side_effect = ['/dev/loop0', '/dev/loop1']
mock_bu.attach_file_to_free_loop_device.side_effect = [
'/dev/loop0', '/dev/loop1']
mock_mkdtemp.return_value = '/tmp/imgdir'
getsize_side = [20, 2, 10, 1]
mock_os.path.getsize.side_effect = getsize_side
@ -867,13 +868,18 @@ class TestImageBuild(unittest2.TestCase):
size=CONF.sparse_file_size)] * 2,
mock_bu.create_sparse_tmp_file.call_args_list)
self.assertEqual(
[mock.call(loop_device_major_number=CONF.loop_device_major_number,
max_loop_devices_count=CONF.max_loop_devices_count),
] * 2,
mock_bu.get_free_loop_device.call_args_list)
self.assertEqual([mock.call('/tmp/img', '/dev/loop0'),
mock.call('/tmp/img-boot', '/dev/loop1')],
mock_bu.attach_file_to_loop.call_args_list)
[mock.call(
'/tmp/img',
loop_device_major_number=CONF.loop_device_major_number,
max_loop_devices_count=CONF.max_loop_devices_count,
max_attempts=CONF.max_allowed_attempts_attach_image),
mock.call(
'/tmp/img-boot',
loop_device_major_number=CONF.loop_device_major_number,
max_loop_devices_count=CONF.max_loop_devices_count,
max_attempts=CONF.max_allowed_attempts_attach_image)
],
mock_bu.attach_file_to_free_loop_device.call_args_list)
self.assertEqual([mock.call(fs_type='ext4', fs_options='',
fs_label='', dev='/dev/loop0'),
mock.call(fs_type='ext2', fs_options='',

42
fuel_agent/utils/build.py
View File

@ -455,3 +455,45 @@ def containerize(filename, container, chunk_size=1048576):
raise errors.WrongImageDataError(
'Error while image initialization: '
'unsupported image container: {container}'.format(container=container))
def attach_file_to_free_loop_device(filename, max_loop_devices_count=255,
loop_device_major_number=7,
max_attempts=1):
"""Find free loop device and try to attach `filename` to it.
If attaching fails then retry again. Max allowed attempts is
`max_attempts`.
Returns loop device to which file is attached. Otherwise, raises
errors.NoFreeLoopDevices.
"""
loop_device = None
for i in range(0, max_attempts):
try:
LOG.debug('Looking for a free loop device')
loop_device = get_free_loop_device(
loop_device_major_number=loop_device_major_number,
max_loop_devices_count=max_loop_devices_count)
log_msg = "Attaching image file '{0}' to free loop device '{1}'"
LOG.debug(log_msg.format(filename, loop_device))
attach_file_to_loop(filename, loop_device)
break
except errors.ProcessExecutionError:
log_msg = "Couldn't attach image file '{0}' to loop device '{1}'."
LOG.debug(log_msg.format(filename, loop_device))
if i == max_attempts - 1:
log_msg = ("Maximum allowed attempts ({0}) to attach image "
"file '{1}' to loop device '{2}' is exceeded.")
LOG.debug(log_msg.format(max_attempts, filename, loop_device))
raise errors.NoFreeLoopDevices('Free loop device not found.')
else:
log_msg = ("Trying again to attach image file '{0}' "
"to free loop device '{1}'. "
"Attempt #{2} out of {3}")
LOG.debug(log_msg.format(filename, loop_device,
i + 1, max_attempts))
return loop_device