On Tue, Jul 4, 2017 at 8:00 PM, Chandan Rajendra
<chandan@xxxxxxxxxxxxxxxxxx> wrote:
> With constant st_dev implemented, overlayfs never returns the real dev
> corresponding to lowerdir filesystems. Also, for the samefs case,
> overlayfs always returns the pseudo st_dev corresponding to the union
> layer.
>
> Signed-off-by: Chandan Rajendra <chandan@xxxxxxxxxxxxxxxxxx>
Chandan,
Tests look correct, however, the tests are correct for a future
version of overlayfs
(overlayfs-devel branch) and we don't want to break unionmounts for current
stable kernel and not even for older kernels, so we have to maintain backward
compat somehow...
I suggest that you use the config flag self.config().is_verify(),
which I already
introduced in order to support old kernels w.r.t constant ino check,
as an indication for which st_dev can be expected in layer check.
I think the rules should be:
1. ./run --verify --samefs # should enforce all dentries on overlay st_dev
2. ./run --verify # should enforce the rules that you wrote
3. ./run [--samefs] # should allow for either old kernel rules or new rules
Your challenge is to manage to describe all those rules in a clean and
short way,
just like you did with this patch.
Good luck!
Amir.
(see two more comments below)
> ---
> context.py | 10 ++++------
> 1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/context.py b/context.py
> index 829fb69..f6dbbe7 100644
> --- a/context.py
> +++ b/context.py
> @@ -532,17 +532,15 @@ class test_context:
> if self.skip_layer_test():
> pass
> elif dev == self.lower_fs():
> - if dentry.is_dir():
> - raise TestError(name + ": Directory unexpectedly on lower filesystem")
> + # Overlayfs never returns st_dev corresponding to any of
> + # the lower layers
> + raise TestError(name + ": File unexpectedly has lowerfs dev id")
> elif dentry.is_dir():
> if dev != self.upper_dir_fs():
> raise TestError(name + ": Directory not on union layer")
> elif dev == self.upper_fs() and not dentry.on_upper():
> raise TestError(name + ": File unexpectedly on upper layer")
You can and should also add the opposite check to enforce that:
if dentry.on_upper() and not self.config().is_samefs() and dev !=
self.upper_fs():
"File unexpectedly not on upper layer"
> - elif dev != self.upper_fs() and dev != self.upper_dir_fs() and self.config().is_samefs():
> - # For samefs, file is on overlay dev
> - # TODO: for non-samefs, check file dev matches pseudo dev
> - # and that pseduo dev != real dev
> + elif dev != self.upper_dir_fs() and self.config().is_samefs():
> raise TestError(name + ": File on unexpected layer")
Here, the error could be more descriptive "File not on union layer"
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