[LTP] [PATCH v2 2/4] syscalls/fanotify15: Add a test case for inode marks

[Petr Vorel]

Hi Jan,

...
> > > > The new test case is a regression test for commit f367a62a7cad:

> > > >     fanotify: merge duplicate events on parent and child

> > > The test looks OK but do we want a test for this? I mean: A test like this
> > > seems to imply we promise to merge identical events. Although that is a
> > > good general guideline, I consider it rather an optimization that may or
> > > may not happen but userspace should not rely on it. Thoughts?

> > The thing is, those are not really two identical events.
> > This is in fact the same event (fsnotify_change() hook was called once).
> > The fact that listener process may have an inode watch, parent directory
> > watch and a filesystem watch should not affect the number of read events.

> Yeah, I agree that in this case we should be merging the event if sanely
> possible (which is why I've merged that patch).

> > Now it's true that internally, fsnotify_dentry() emits two event flavors to
> > parent and to victim. For inotify it even made some sense, because listener
> > would read two different event flavors with two different formats.
> > With fanotify (either reporting fd or fid) receiving two events makes very
> > little sense.

> > I agree that the fix (merging those events) is best effort and we cannot
> > commit to merging the events, but this isolated regression test does
> > check the best effort fix reliably and this is the reason I think it
> > should stay.

> OK, I'm not too concerned about this test. But still the functionality is
> more in the area of "nice to have" than "must have" so in future we may
> break this if the implementation would get too hairy. But I guess we can
> remove the test in that case.
Yes, nothing is set in stone.

> > Upcoming FAN_REPORT_NAME is about to change the picture a bit
> > towards the inotify behavior - victim watch gets event without name,
> > parent watch gets event with name, filesystem watch gets both event
> > flavors... that is, if you will agree to this behavior, but we shall continue
> > this discussion on the fanotiify_name patches....

> Yes.
Can I add your ack tag to the whole patchset?
Or do you still consider whether any of them should be merged?

Kind regards,
Petr

> 								Honza