Jens Harbott
14d98ef1b4
The current check uses an alignment of 512 bytes and will fail when the underlying device has sectors of size 4096 bytes, as is common e.g. for NVMe disks. So use an alignment of 4096 bytes, which is a multiple of 512 bytes and thus will cover both cases. Change-Id: I5151ae01e90506747860d9780547b0d4ce91d8bc Closes-Bug: 1801702 Co-Authored-By: Alexandre Arents <alexandre.arents@corp.ovh.com>
79 lines
2.7 KiB
Python
79 lines
2.7 KiB
Python
# Copyright 2010 United States Government as represented by the
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# Administrator of the National Aeronautics and Space Administration.
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# Copyright 2011 Justin Santa Barbara
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# Copyright 2018 Michael Still and Aptira
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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# This module is utility methods that privsep depends on. Privsep isn't allowed
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# to depend on anything outside the privsep directory, so these need to be
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# here. That said, other parts of nova can call into these utilities if
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# needed.
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import errno
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import mmap
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import os
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from oslo_log import log as logging
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from oslo_utils import excutils
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LOG = logging.getLogger(__name__)
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def supports_direct_io(dirpath):
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if not hasattr(os, 'O_DIRECT'):
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LOG.debug("This python runtime does not support direct I/O")
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return False
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testfile = os.path.join(dirpath, ".directio.test")
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hasDirectIO = True
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fd = None
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try:
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fd = os.open(testfile, os.O_CREAT | os.O_WRONLY | os.O_DIRECT)
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# Check is the write allowed with 4096 byte alignment
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align_size = 4096
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m = mmap.mmap(-1, align_size)
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m.write(b"x" * align_size)
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os.write(fd, m)
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LOG.debug("Path '%(path)s' supports direct I/O",
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{'path': dirpath})
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except OSError as e:
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if e.errno in (errno.EINVAL, errno.ENOENT):
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LOG.debug("Path '%(path)s' does not support direct I/O: "
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"'%(ex)s'", {'path': dirpath, 'ex': e})
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hasDirectIO = False
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else:
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with excutils.save_and_reraise_exception():
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LOG.error("Error on '%(path)s' while checking "
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"direct I/O: '%(ex)s'",
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{'path': dirpath, 'ex': e})
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except Exception as e:
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with excutils.save_and_reraise_exception():
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LOG.error("Error on '%(path)s' while checking direct I/O: "
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"'%(ex)s'", {'path': dirpath, 'ex': e})
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finally:
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# ensure unlink(filepath) will actually remove the file by deleting
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# the remaining link to it in close(fd)
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if fd is not None:
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os.close(fd)
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try:
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os.unlink(testfile)
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except Exception:
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pass
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return hasDirectIO
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