Re: [RFC 1/2] fanotify: new event FAN_MODIFY_DIR
From: Filip ÅtÄdronskÃ
Date: Tue Mar 14 2017 - 08:42:18 EST
Hi,
On Tue, Mar 14, 2017 at 12:11:40PM +0200, Amir Goldstein wrote:
> > - file system indexers / desktop search tools
> > - file synchronization tools (like Dropbox, Nextcloud, etc.),
> > online backup tools
>
> This last one is the use case of my employer, Ctera Networks.
> Out of curiosity, what is the use case that you are focusing on?
I'm working on a file synchronization tool as part of my bachelor
thesis at Charles University.
When I started (now over a year ago ... long story), there were AFIK no
attempts at solving the recursive inotify issue, only a lot of
complaints, so I cobbled up together something simple (I'm not a kernel
developer by trade, this was my first patch) that would allow me to
work on the userspace parts, which are the main bulk.
I try to focus on algorithmic and implementation efficiency as opposed
to fancy GUIs and similar. I want it to be fast with 100k directories
and 10M files in home dir. But it's very WIP so we'll see how that turns
out.
> I had the feeling that all recursive inotify users are hiding in the shadows,
> but was missing more concrete evidence.
Yes, even Dropbox uses inotify. They have articles in their help on how
to increase inotify.max_user_watches: https://www.dropbox.com/help/145.
That's not good PR. ;-) (I'm not affiliated with DB, just pointing that
out.)
> About the argument of not having to change in-kernel framework,
> I don't think it should be a consideration at all.
Understood. I tried to stay conservative and non-controversial because I
imagined that radical framework changes would take months of discussions
(look at the history of statx) and this issue seems to be pressing for
quite a lot of people. But rushing is of course not the best strategy
either, there are always compromises.
> If you don't specify FAN_EVENT_INFO_NAME, you can get filename events
> FAN_MOVE|FAN_CREATE|FAN_DELETE without the name.
>
> What you do get is the file descriptor of the parent. sounds familiar? ;-)
I didn't notice this bit. That sounds like a win-win.
Filip