libvirt: Report the allocated size of preallocated file based disks
At present the Libvirt driver can preallocate file based disks using the
fallocate command and importantly the `-n` option. This option allocates
blocks on the filesystem past the initial EOF of a given file:
```
$ touch test.img ; fallocate -n -l $(( 1024 * 1024 )) test.img
$ ll -lah test.img
-rw-rw-r--. 1 stack stack 0 Apr 16 13:28 test.img
$ du -h test.img
1.0M test.img
```
This results in a miscalculation of the total disk overcommit for file
based (excluding ploop) disks as os.path.getsize is currently used to
determine the allocated size of these disks:
```
>>> import os
>>> os.path.getsize('test.img')
0
```
Using the above example the disk overcommit would be reported as 1.0M as
the disk appears empty yet will report a potential (virtual) size of 1.0M.
However as the required blocks have already been allocated on the
filesystem the host will report disk_available_least as missing an
additional 1.0M, essentially doubling the allocation for each disk.
To correct this the allocated size of file based (excluding ploop) disks
is reported using `disk_size` from the `qemu-img info` command. This
should ensure blocks allocated past the EOF of the file are taken into
account and correctly reported as allocated.
A future change should ultimately remove the use of the `-n` option with
fallocate, however as this would not help disks that have already been
allocated this has not been included in this change to simplify backports.
Conflicts:
nova/tests/unit/virt/libvirt/test_driver.py
NOTE(lyarwood): I11e329ac5f5fe4b9819fefbcc32ff1ee504fc58b made
get_domain private in Queens.
Change-Id: If642e51a4e186833349a8e30b04224a3687f5594
Closes-bug: #1764489
(cherry picked from commit 23bd8f6263)
(cherry picked from commit 2d50f6e785)
This commit is contained in:
Lee Yarwood
parent
39b28d0bc9
commit
d88b75e81e
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@ -4162,8 +4162,9 @@ class LibvirtConnTestCase(test.NoDBTestCase,
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@mock.patch.object(dmcrypt, 'delete_volume')
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@mock.patch.object(conn._host, 'get_domain', return_value=dom)
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def detach_encrypted_volumes(block_device_info, mock_get_domain,
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mock_delete_volume):
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@mock.patch.object(libvirt_driver.disk_api, 'get_allocated_disk_size')
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def detach_encrypted_volumes(block_device_info, mock_get_alloc_size,
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mock_get_domain, mock_delete_volume):
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conn._detach_encrypted_volumes(instance, block_device_info)
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mock_get_domain.assert_called_once_with(instance)
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@ -8158,6 +8159,8 @@ class LibvirtConnTestCase(test.NoDBTestCase,
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is_shared_instance_path=False)
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with test.nested(
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mock.patch.object(os.path, 'getsize', mock_getsize),
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mock.patch.object(libvirt_driver.disk_api,
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'get_allocated_disk_size', mock_getsize),
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mock.patch.object(host.Host, 'get_domain', mock_lookup)):
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self.assertFalse(drvr._is_shared_block_storage(
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instance, data,
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@ -10625,9 +10628,14 @@ class LibvirtConnTestCase(test.NoDBTestCase,
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fake_libvirt_utils.disk_sizes['/test/disk.local'] = 20 * units.Gi
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fake_libvirt_utils.disk_backing_files['/test/disk.local'] = 'file'
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self.mox.StubOutWithMock(os.path, "getsize")
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os.path.getsize('/test/disk').AndReturn((10737418240))
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os.path.getsize('/test/disk.local').AndReturn((3328599655))
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self.mox.StubOutWithMock(libvirt_driver.disk_api,
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'get_allocated_disk_size')
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path = '/test/disk'
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size = 10737418240
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libvirt_driver.disk_api.get_allocated_disk_size(path).AndReturn((size))
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path = '/test/disk.local'
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size = 3328599655
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libvirt_driver.disk_api.get_allocated_disk_size(path).AndReturn((size))
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ret = ("image: /test/disk.local\n"
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"file format: qcow2\n"
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@ -10735,9 +10743,14 @@ class LibvirtConnTestCase(test.NoDBTestCase,
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fake_libvirt_utils.disk_sizes['/test/disk.local'] = 20 * units.Gi
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fake_libvirt_utils.disk_backing_files['/test/disk.local'] = 'file'
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self.mox.StubOutWithMock(os.path, "getsize")
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os.path.getsize('/test/disk').AndReturn((10737418240))
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os.path.getsize('/test/disk.local').AndReturn((3328599655))
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self.mox.StubOutWithMock(libvirt_driver.disk_api,
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'get_allocated_disk_size')
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path = '/test/disk'
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size = 10737418240
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libvirt_driver.disk_api.get_allocated_disk_size(path).AndReturn((size))
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path = '/test/disk.local'
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size = 3328599655
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libvirt_driver.disk_api.get_allocated_disk_size(path).AndReturn((size))
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ret = ("image: /test/disk.local\n"
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"file format: qcow2\n"
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@ -10801,8 +10814,11 @@ class LibvirtConnTestCase(test.NoDBTestCase,
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fake_libvirt_utils.disk_sizes['/test/disk'] = 10 * units.Gi
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self.mox.StubOutWithMock(os.path, "getsize")
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os.path.getsize('/test/disk').AndReturn((10737418240))
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self.mox.StubOutWithMock(libvirt_driver.disk_api,
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"get_allocated_disk_size")
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path = '/test/disk'
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size = 10737418240
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libvirt_driver.disk_api.get_allocated_disk_size(path).AndReturn((size))
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self.mox.ReplayAll()
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drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
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@ -10811,8 +10827,8 @@ class LibvirtConnTestCase(test.NoDBTestCase,
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info = jsonutils.loads(info)
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self.assertEqual(1, len(info))
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self.assertEqual(info[0]['type'], 'raw')
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self.assertEqual(info[0]['path'], '/test/disk')
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self.assertEqual(info[0]['disk_size'], 10737418240)
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self.assertEqual(info[0]['path'], path)
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self.assertEqual(info[0]['disk_size'], size)
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self.assertEqual(info[0]['backing_file'], "")
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self.assertEqual(info[0]['over_committed_disk_size'], 0)
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@ -146,6 +146,16 @@ def get_disk_size(path):
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return images.qemu_img_info(path).virtual_size
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def get_allocated_disk_size(path):
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"""Get the allocated size of a disk image
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:param path: Path to the disk image
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:returns: Size (in bytes) of the given disk image as allocated on the
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filesystem
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"""
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return images.qemu_img_info(path).disk_size
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def extend(image, size):
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"""Increase image to size.
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@ -7354,7 +7354,7 @@ class LibvirtDriver(driver.ComputeDriver):
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fp = os.path.join(dirpath, f)
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dk_size += os.path.getsize(fp)
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else:
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dk_size = int(os.path.getsize(path))
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dk_size = disk_api.get_allocated_disk_size(path)
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elif disk_type == 'block' and block_device_info:
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dk_size = lvm.get_volume_size(path)
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else:
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