Re: [PATCH for-9.0 1/3] qtest/virtio-9p-test.c: consolidate create dir, file and symlink tests

[Christian Schoenebeck <qemu_oss@crudebyte.com>]

On Wednesday, March 27, 2024 10:33:27 AM CET Daniel Henrique Barboza wrote:
> On 3/27/24 05:47, Christian Schoenebeck wrote:
> > On Tuesday, March 26, 2024 6:47:17 PM CET Daniel Henrique Barboza wrote:
> >> On 3/26/24 14:05, Greg Kurz wrote:
> >>> On Tue, 26 Mar 2024 10:26:04 -0300
> >>> Daniel Henrique Barboza <dbarboza@ventanamicro.com> wrote:
> >>>
> >>>> The local 9p driver in virtio-9p-test.c its temporary dir right at the
> >>>> start of qos-test (via virtio_9p_create_local_test_dir()) and only
> >>>> deletes it after qos-test is finished (via
> >>>> virtio_9p_remove_local_test_dir()).
> >>>>
> >>>> This means that any qos-test machine that ends up running virtio-9p-test local
> >>>> tests more than once will end up re-using the same temp dir. This is
> >>>> what's happening in [1] after we introduced the riscv machine nodes: if
> >>>> we enable slow tests with the '-m slow' flag using qemu-system-riscv64,
> >>>> this is what happens:
> >>>>
> >>>> - a temp dir is created, e.g. qtest-9p-local-WZLDL2;
> >>>>
> >>>> - virtio-9p-device tests will run virtio-9p-test successfully;
> >>>>
> >>>> - virtio-9p-pci tests will run virtio-9p-test, and fail right at the
> >>>>     first slow test at fs_create_dir() because the "01" file was already
> >>>>     created by fs_create_dir() test when running with the virtio-9p-device.
> >>>>
> >>>> We can fix it by making every test clean up their changes in the
> >>>> filesystem after they're done. But we don't need every test either:
> >>>> what fs_create_file() does is already exercised in fs_unlinkat_dir(),
> >>>> i.e. a dir is created, verified to be created, and then removed. Fixing
> >>>> fs_create_file() would turn it into fs_unlikat_dir(), so we don't need
> >>>> both. The same theme follows every test in virtio-9p-test.c, where the
> >>>> 'unlikat' variant does the same thing the 'create' does but with some
> >>>> cleaning in the end.
> >>>>
> >>>> Consolide some tests as follows:
> >>>>
> >>>> - fs_create_dir() is removed. fs_unlinkat_dir() is renamed to
> >>>>     fs_create_unlinkat_dir();
> >>>>
> >>>> - fs_create_file() is removed. fs_unlinkat_file() is renamed to
> >>>>     fs_create_unlinkat_file(). The "04" dir it uses is now being removed;
> >>>>
> >>>> - fs_symlink_file() is removed. fs_unlinkat_symlink() is renamed to
> >>>>     fs_create_unlinkat_symlink(). Both "real_file" and the "06" dir it
> >>>>     creates is now being removed.
> >>>>
> >>>
> >>> The  change looks good functionally but it breaks the legitimate assumption
> >>> that files "06/*" come from test #6 and so on... I think you should consider
> >>> renumbering to avoid confusion when debugging logs.
> >>>
> >>> Since this will bring more hunks, please split this in enough reviewable
> >>> patches.
> >>
> >> Fair enough. Let me cook a v2. Thanks,
> > 
> > Wouldn't it be much simpler to just change the name of the temporary
> > directory, such that it contains the device name as well? Then these tests
> > runs would run on independent directories and won't interfere with each other
> > and that wouldn't need much changes I guess.
> 
> That's true. If we were just trying to fix the issue then I would go with this
> approach since it's simpler. But given that we're also cutting half the tests while
> retaining the coverage I think this approach is worth the extra code.

Well, I am actually not so keen into all those changes. These tests were
intentionally split, and yes with costs of a bit redundant (test case) code.
But they were cleanly build up on each other, from fundamental requirements
like whether it is possible to create a directory and file ... and then the
subsequent tests would become more and more demanding.

That way it was easier to review if somebody reports a test to fail, because
you could immediately see whether the preceding fundamental tests succeeded.

/Christian