Messages in this thread | | | Date | Mon, 27 Oct 2014 20:02:51 +0400 | Subject | Re: A desktop environment[1] kernel wishlist | From | "Sergey \"Shnatsel\" Davidoff" <> |
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> If "recursive mtime" was available, would that work for you?
It would work for detecting "offline" changes. I suppose recursive mtime not viable for online monitoring, mostly because detecting file renaming would be a massive PITA (and we already have fanotify with exactly this problem).
Another approach to offline monitoring is using things like btrfs changelogs - e.g. incremental "btrfs send", but I don't think that's viable for other filesystems and I don't know how efficient it is even on btrfs.
Actually, being able to read btrfs changelog from userspace more or less as it happens (<200ms latency on commodity x86) would fulfill our requirements for online VFS monitoring facility, and we could use "btrfs send" approach for replaying offline changes. The good thing about this approach is that it can use a fixed-size buffer for feeding the info in userspace - if userspace can't keep up, the data is not lost but recorded to the filesystem and can be retrieved from it later. In this case we'd be tied to a specific filesystem, but that's worlds better than nothing at all.
-- Sergey "Shnatsel" Davidoff
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