Hello Heinrich, On Thu 13-11-14 20:57:23, Heinrich Schuchardt wrote: > could you, please, give me some feedback for > https://lkml.org/lkml/2014/10/6/380 Oh, I completely forgot about that one... > Currently truncate() only generates an IN_MODIFY event. > > Do you agree that it also should additionally create > FAN_OPEN_PERM, FAN_OPEN, IN_OPEN, FAN_MODIFY, FAN_CLOSE_WRITE, > IN_CLOSE_WRITE as well? > > IN_CLOSE_WRITE is used by editors to warn the user about updated files. > > FAN_OPEN_PERM, FAN_MODIFY, and FAN_CLOSE_WRITE would be relevant for > a malware scanner. > > FAN_OPEN_PERM would be needed if the fanotify interface were used to > build a hierarchical storage managers. I agree about FAN_MODIFY, that is a clear bug. OPEN / CLOSE events are generated on open / close. Noone really guarantees you that to modify a file you have to open it. So I agree they would make life simpler for userspace but at this point I don't think we can change the user interface in such way :(. I can imagine that especially for content checkers the fact that file can be truncated without FAN_OPEN_PERM is rather unpleasant (OTOH file can be unlinked & replaced in a directory also without FAN_OPEN_PERM so it doesn't seem like a completely new problem area either). The cleanest way I see how we could deal with the situation is to add a new type of event. Maybe something like IN_TRUNCATE, FAN_TRUNCATE, FAN_TRUNCATE_PERM - and userspace application aware of the problem could use these events instead of watching for IN_MODIFY / FAN_MODIFY which is generated rather frequently. But this definitely needs more thought - we have to carefully define when the events get generated so that they are useful - is e.g. punching holes and similar fallocate tricks elligible as well? What about ftruncate() where you have open file descriptor? Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
