Merge "image_utils: Detect missing device before calling qemu-img convert"

cinder/image/image_utils.py

@@ -51,6 +51,7 @@ from cinder.i18n import _
 from cinder.image import accelerator
 from cinder.image import glance
 import cinder.privsep.format_inspector
+import cinder.privsep.path
 from cinder import utils
 from cinder.volume import throttling
 from cinder.volume import volume_utils
@@ -376,6 +377,16 @@ def check_qemu_img_version(minimum_version: str) -> None:
         raise exception.VolumeBackendAPIException(data=_msg)
 
 
+def _ensure_exists(dest_path: str) -> None:
+    # Ensure that "dest" exists if it is in /dev/
+    # This prevents qemu-img from creating a file in /dev/
+    # if the block device has disappeared.
+    if dest_path.startswith('/dev/'):
+        if not cinder.privsep.path.exists(dest_path):
+            raise exception.CinderException(
+                "qemu-img convert destination %s does not exist" % dest_path)
+
+
 def _convert_image(
         prefix: tuple,
         source: str,
@@ -443,6 +454,8 @@ def _convert_image(
                                 src_passphrase_file=src_passphrase_file,
                                 disable_sparse=disable_sparse)
 
+    _ensure_exists(dest)
+
     start_time = timeutils.utcnow()
 
     # If there is not enough space on the conversion partition, include

cinder/privsep/path.py

@@ -37,3 +37,8 @@ def symlink(src, dest):
     if not os.path.exists(src):
         raise exception.FileNotFound(file_path=src)
     os.symlink(src, dest)
+
+
+@cinder.privsep.sys_admin_pctxt.entrypoint
+def exists(path: str | os.PathLike) -> bool:
+    return os.path.exists(path)

cinder/tests/unit/test_image_utils.py

@@ -264,6 +264,8 @@ class TestQemuImgInfo(test.TestCase):
 
 @ddt.ddt
 class TestConvertImage(test.TestCase):
+    @mock.patch('cinder.image.image_utils._ensure_exists',
+                new=mock.MagicMock())
     @mock.patch('cinder.image.image_utils.qemu_img_info')
     @mock.patch('cinder.utils.execute')
     @mock.patch('cinder.utils.is_blk_device', return_value=True)
@@ -296,6 +298,8 @@ class TestConvertImage(test.TestCase):
                                               '-O', out_format, source, dest,
                                               run_as_root=True)
 
+    @mock.patch('cinder.image.image_utils._ensure_exists',
+                new=mock.MagicMock())
     @mock.patch('cinder.image.image_utils.qemu_img_info')
     @mock.patch('cinder.utils.execute')
     @mock.patch('cinder.utils.is_blk_device', return_value=True)
@@ -333,6 +337,8 @@ class TestConvertImage(test.TestCase):
                                               '-O', out_format, source, dest,
                                               run_as_root=True)
 
+    @mock.patch('cinder.image.image_utils._ensure_exists',
+                new=mock.MagicMock())
     @mock.patch('cinder.volume.volume_utils.check_for_odirect_support',
                 return_value=True)
     @mock.patch('cinder.image.image_utils.qemu_img_info')
@@ -358,6 +364,8 @@ class TestConvertImage(test.TestCase):
                                           source, dest,
                                           run_as_root=True)
 
+    @mock.patch('cinder.image.image_utils._ensure_exists',
+                new=mock.MagicMock())
     @mock.patch('cinder.volume.volume_utils.check_for_odirect_support',
                 return_value=True)
     @mock.patch('cinder.image.image_utils.qemu_img_info')
@@ -383,6 +391,8 @@ class TestConvertImage(test.TestCase):
                                           source, dest,
                                           run_as_root=True)
 
+    @mock.patch('cinder.image.image_utils._ensure_exists',
+                new=mock.MagicMock())
     @mock.patch('cinder.image.image_utils.qemu_img_info')
     @mock.patch('cinder.utils.execute')
     @mock.patch('cinder.utils.is_blk_device', return_value=True)
@@ -403,6 +413,8 @@ class TestConvertImage(test.TestCase):
                                               '-O', out_format, '-t', 'none',
                                               source, dest, run_as_root=True)
 
+    @mock.patch('cinder.image.image_utils._ensure_exists',
+                new=mock.MagicMock())
     @mock.patch('cinder.image.image_utils.qemu_img_info')
     @mock.patch('cinder.utils.execute')
     @mock.patch('cinder.utils.is_blk_device', return_value=False)
@@ -422,6 +434,8 @@ class TestConvertImage(test.TestCase):
                                           source, dest, run_as_root=True)
 
     @ddt.data(True, False)
+    @mock.patch('cinder.image.image_utils._ensure_exists',
+                new=mock.MagicMock())
     @mock.patch('cinder.image.image_utils.qemu_img_info')
     @mock.patch('cinder.utils.execute')
     @mock.patch('cinder.utils.is_blk_device', return_value=False)
@@ -446,6 +460,8 @@ class TestConvertImage(test.TestCase):
         mock_exec.assert_called_once_with(*exec_args,
                                           run_as_root=True)
 
+    @mock.patch('cinder.image.image_utils._ensure_exists',
+                new=mock.MagicMock())
     @mock.patch('cinder.image.image_utils.qemu_img_info')
     @mock.patch('cinder.utils.execute')
     @mock.patch('cinder.utils.is_blk_device', return_value=False)
@@ -464,6 +480,8 @@ class TestConvertImage(test.TestCase):
                                           '-O', out_format, '-S', '0', source,
                                           dest, run_as_root=True)
 
+    @mock.patch('cinder.image.image_utils._ensure_exists',
+                new=mock.MagicMock())
     @mock.patch('cinder.volume.volume_utils.check_for_odirect_support',
                 return_value=True)
     @mock.patch('cinder.image.image_utils.qemu_img_info')

releasenotes/notes/bug-2132083-detect-missing-dev-during-img-conversion-ae80feda55ca7550.yaml

@@ -0,0 +1,8 @@
+---
+fixes:
+  - |
+    `Bug #2132083 <https://bugs.launchpad.net/cinder/+bug/2132083>`_: When
+    creating a volume from an image, a storage connectivity failure or
+    similar could result in the local block device node disappearing. In
+    this situation, avoid writing the image to a file in /dev/ when calling
+    qemu-img.