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# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# All Rights Reserved.
# Copyright (c) 2010 Citrix Systems, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""
Handling of VM disk images.
"""
import operator
import os
from oslo_concurrency import processutils
from oslo_log import log as logging
from oslo_utils import fileutils
from oslo_utils import imageutils
from oslo_utils import units
import nova.conf
from nova import exception
from nova.i18n import _
from nova import image
from nova import utils
LOG = logging.getLogger(__name__)
CONF = nova.conf.CONF
IMAGE_API = image.API()
QEMU_IMG_LIMITS = processutils.ProcessLimits(
cpu_time=30,
address_space=1 * units.Gi)
# This is set by the libvirt driver on startup. The version is used to
# determine what flags need to be set on the command line.
QEMU_VERSION = None
QEMU_VERSION_REQ_SHARED = 2010000
def qemu_img_info(path, format=None):
"""Return an object containing the parsed output from qemu-img info."""
# TODO(mikal): this code should not be referring to a libvirt specific
# flag.
if not os.path.exists(path) and CONF.libvirt.images_type != 'rbd':
raise exception.DiskNotFound(location=path)
try:
# The following check is about ploop images that reside within
# directories and always have DiskDescriptor.xml file beside them
if (os.path.isdir(path) and
os.path.exists(os.path.join(path, "DiskDescriptor.xml"))):
path = os.path.join(path, "root.hds")
cmd = ('env', 'LC_ALL=C', 'LANG=C', 'qemu-img', 'info', path)
if format is not None:
cmd = cmd + ('-f', format)
# Check to see if the qemu version is >= 2.10 because if so, we need
# to add the --force-share flag.
if QEMU_VERSION and operator.ge(QEMU_VERSION, QEMU_VERSION_REQ_SHARED):
cmd = cmd + ('--force-share',)
out, err = utils.execute(*cmd, prlimit=QEMU_IMG_LIMITS)
except processutils.ProcessExecutionError as exp:
if exp.exit_code == -9:
# this means we hit prlimits, make the exception more specific
msg = (_("qemu-img aborted by prlimits when inspecting "
"%(path)s : %(exp)s") % {'path': path, 'exp': exp})
elif exp.exit_code == 1 and 'No such file or directory' in exp.stderr:
# The os.path.exists check above can race so this is a simple
# best effort at catching that type of failure and raising a more
# specific error.
raise exception.DiskNotFound(location=path)
else:
msg = (_("qemu-img failed to execute on %(path)s : %(exp)s") %
{'path': path, 'exp': exp})
raise exception.InvalidDiskInfo(reason=msg)
if not out:
msg = (_("Failed to run qemu-img info on %(path)s : %(error)s") %
{'path': path, 'error': err})
raise exception.InvalidDiskInfo(reason=msg)
return imageutils.QemuImgInfo(out)
def convert_image(source, dest, in_format, out_format, run_as_root=False):
"""Convert image to other format."""
if in_format is None:
raise RuntimeError("convert_image without input format is a security"
" risk")
_convert_image(source, dest, in_format, out_format, run_as_root)
def convert_image_unsafe(source, dest, out_format, run_as_root=False):
"""Convert image to other format, doing unsafe automatic input format
detection. Do not call this function.
"""
# NOTE: there is only 1 caller of this function:
# imagebackend.Lvm.create_image. It is not easy to fix that without a
# larger refactor, so for the moment it has been manually audited and
# allowed to continue. Remove this function when Lvm.create_image has
# been fixed.
_convert_image(source, dest, None, out_format, run_as_root)
def _convert_image(source, dest, in_format, out_format, run_as_root):
# NOTE(mdbooth): qemu-img convert defaults to cache=unsafe, which means
# that data is not synced to disk at completion. We explicitly use
# cache=none here to (1) ensure that we don't interfere with other
# applications using the host's io cache, and (2) ensure that the data is
# on persistent storage when the command exits. Without (2), a host crash
# may leave a corrupt image in the image cache, which Nova cannot recover
# automatically.
# NOTE(zigo): we cannot use -t none if the instances dir is mounted on a
# filesystem that doesn't have support for O_DIRECT, which is the case
# for example with tmpfs. This simply crashes "openstack server create"
# in environments like live distributions. In such case, the best choice
# is writethrough, which is power-failure safe, but still faster than
# writeback.
if utils.supports_direct_io(CONF.instances_path):
cache_mode = 'none'
else:
cache_mode = 'writethrough'
cmd = ('qemu-img', 'convert', '-t', cache_mode, '-O', out_format)
if in_format is not None:
cmd = cmd + ('-f', in_format)
cmd = cmd + (source, dest)
try:
utils.execute(*cmd, run_as_root=run_as_root)
except processutils.ProcessExecutionError as exp:
msg = (_("Unable to convert image to %(format)s: %(exp)s") %
{'format': out_format, 'exp': exp})
raise exception.ImageUnacceptable(image_id=source, reason=msg)
def fetch(context, image_href, path):
with fileutils.remove_path_on_error(path):
IMAGE_API.download(context, image_href, dest_path=path)
def get_info(context, image_href):
return IMAGE_API.get(context, image_href)
def fetch_to_raw(context, image_href, path):
path_tmp = "%s.part" % path
fetch(context, image_href, path_tmp)
with fileutils.remove_path_on_error(path_tmp):
data = qemu_img_info(path_tmp)
fmt = data.file_format
if fmt is None:
raise exception.ImageUnacceptable(
reason=_("'qemu-img info' parsing failed."),
image_id=image_href)
backing_file = data.backing_file
if backing_file is not None:
raise exception.ImageUnacceptable(image_id=image_href,
reason=(_("fmt=%(fmt)s backed by: %(backing_file)s") %
{'fmt': fmt, 'backing_file': backing_file}))
if fmt != "raw" and CONF.force_raw_images:
staged = "%s.converted" % path
LOG.debug("%s was %s, converting to raw", image_href, fmt)
with fileutils.remove_path_on_error(staged):
try:
convert_image(path_tmp, staged, fmt, 'raw')
except exception.ImageUnacceptable as exp:
# re-raise to include image_href
raise exception.ImageUnacceptable(image_id=image_href,
reason=_("Unable to convert image to raw: %(exp)s")
% {'exp': exp})
os.unlink(path_tmp)
data = qemu_img_info(staged)
if data.file_format != "raw":
raise exception.ImageUnacceptable(image_id=image_href,
reason=_("Converted to raw, but format is now %s") %
data.file_format)
os.rename(staged, path)
else:
os.rename(path_tmp, path)
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