On Wed 29-05-19 18:53:21, Amir Goldstein wrote: > > > David, > > > > > > I am interested to know how you envision filesystem notifications would > > > look with this interface. > > > > > > fanotify can certainly benefit from providing a ring buffer interface to read > > > events. > > > > > > From what I have seen, a common practice of users is to monitor mounts > > > (somehow) and place FAN_MARK_MOUNT fanotify watches dynamically. > > > It'd be good if those users can use a single watch mechanism/API for > > > watching the mount namespace and filesystem events within mounts. > > > > > > A similar usability concern is with sb_notify and FAN_MARK_FILESYSTEM. > > > It provides users with two complete different mechanisms to watch error > > > and filesystem events. That is generally not a good thing to have. > > > > > > I am not asking that you implement fs_notify() before merging sb_notify() > > > and I understand that you have a use case for sb_notify(). > > > I am asking that you show me the path towards a unified API (how a > > > typical program would look like), so that we know before merging your > > > new API that it could be extended to accommodate fsnotify events > > > where the final result will look wholesome to users. > > > > Are you sure we want to combine notification about file changes etc. with > > administrator-type notifications about the filesystem? To me these two > > sound like rather different (although sometimes related) things. > > > > Well I am sure that ring buffer for fanotify events would be useful, so > seeing that David is proposing a generic notification mechanism, I wanted > to know how that mechanism could best share infrastructure with fsnotify. > > But apart from that I foresee the questions from users about why the > mount notification API and filesystem events API do not have better > integration. > > The way I see it, the notification queue can serve several classes > of notifications and fsnotify could be one of those classes > (at least FAN_CLASS_NOTIF fits nicely to the model). I agree that for some type of fsnotify uses a ring buffer would make sense. But for others - such as permission events or unlimited queues - you cannot really use the ring buffer and I don't like the idea of having different ways of passing fsnotify events to userspace based on notification group type... Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
