diffApply: set dir opaque when overwriting whiteout #2614
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Before this, there was a bug triggered under the following conditions: 1. An overlay snapshotter was being used, which caused the optimization of preparing a new snapshot off of the base layers to be triggered 2. The base layers contained a directory that had contents 3. One subsequent layer deleted that directory w/out recreating it 4. A later layer recreated the directory In this case, what happened was a whiteout device would be created as part of 3 above but then in step 4 the whiteout device would be removed and replaced with a plain directory. The problem is that such a directory doesn't block out the files from step 2 and it doesn't know about them because they are in a lowerdir (not the upperdir being applied to). The simplest fix, which this commit implements, is to just set the directory created in step 4 as opaque, which enables the correct behavior of blocking out files below it. This was missed in test coverage before because tests for opaque handling always combined 3+4 into one layer, whereas the bug requires they be separate layers. A new integration test has been added to cover this case. Signed-off-by: Erik Sipsma <[email protected]>
tonistiigi
approved these changes
Feb 10, 2022
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Before this, there was a bug triggered under the following conditions:
of preparing a new snapshot off of the base layers to be triggered
In this case, what happened was a whiteout device would be created as
part of 3 above but then in step 4 the whiteout device would be removed
and replaced with a plain directory. The problem is that such a
directory doesn't block out the files from step 2 and it doesn't know
about them because they are in a lowerdir (not the upperdir being
applied to).
The simplest fix, which this commit implements, is to just set the
directory created in step 4 as opaque, which enables the correct
behavior of blocking out files below it.
This was missed in test coverage before because tests for opaque
handling always combined 3+4 into one layer, whereas the bug requires
they be separate layers. A new integration test has been added to cover
this case.
Signed-off-by: Erik Sipsma [email protected]