Re: [RFC 1/2] fanotify: new event FAN_MODIFY_DIR

From	Filip Štědronský <r.lkml@regnarg.cz>
Newsgroups	linux.kernel
Subject	Re: [RFC 1/2] fanotify: new event FAN_MODIFY_DIR
Date	2017-03-14 13:50 +0100
Message-ID	<tkU3L-8W-7@gated-at.bofh.it> (permalink)
References	<tkHgd-808-1@gated-at.bofh.it> <tkRIC-70X-11@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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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

Thread

[RFC 1/2] fanotify: new event FAN_MODIFY_DIR Filip Štědronský <r.lklm@regnarg.cz> - 2017-03-14 00:10 +0100
  Re: [RFC 1/2] fanotify: new event FAN_MODIFY_DIR Filip Štědronský <r.lklm@regnarg.cz> - 2017-03-14 00:20 +0100
    Re: [RFC 1/2] fanotify: new event FAN_MODIFY_DIR Amir Goldstein <amir73il@gmail.com> - 2017-03-14 11:50 +0100
      Re: [RFC 1/2] fanotify: new event FAN_MODIFY_DIR Filip Štědronský <r.lkml@regnarg.cz> - 2017-03-14 15:00 +0100
        Re: [RFC 1/2] fanotify: new event FAN_MODIFY_DIR Amir Goldstein <amir73il@gmail.com> - 2017-03-14 16:10 +0100
        Re: [RFC 1/2] fanotify: new event FAN_MODIFY_DIR Amir Goldstein <amir73il@gmail.com> - 2017-03-20 13:20 +0100
  [RFC 2/2] fanotify: emit FAN_MODIFY_DIR on filesystem changes Filip Štědronský <r.lklm@regnarg.cz> - 2017-03-14 00:20 +0100
    Re: [RFC 2/2] fanotify: emit FAN_MODIFY_DIR on filesystem changes Amir Goldstein <amir73il@gmail.com> - 2017-03-14 12:20 +0100
      Re: [RFC 2/2] fanotify: emit FAN_MODIFY_DIR on filesystem changes Filip Štědronský <r.lkml@regnarg.cz> - 2017-03-14 16:00 +0100
        Re: [RFC 2/2] fanotify: emit FAN_MODIFY_DIR on filesystem changes Amir Goldstein <amir73il@gmail.com> - 2017-03-14 16:40 +0100
        Re: [RFC 2/2] fanotify: emit FAN_MODIFY_DIR on filesystem changes Marko Rauhamaa <marko.rauhamaa@f-secure.com> - 2017-03-15 09:50 +0100
          Re: [RFC 2/2] fanotify: emit FAN_MODIFY_DIR on filesystem changes Jan Kara <jack@suse.cz> - 2017-03-15 14:50 +0100
            Re: [RFC 2/2] fanotify: emit FAN_MODIFY_DIR on filesystem changes Marko Rauhamaa <marko.rauhamaa@f-secure.com> - 2017-03-15 15:20 +0100
            Re: [RFC 2/2] fanotify: emit FAN_MODIFY_DIR on filesystem changes Amir Goldstein <amir73il@gmail.com> - 2017-03-15 15:50 +0100
      Re: [RFC 2/2] fanotify: emit FAN_MODIFY_DIR on filesystem changes Jan Kara <jack@suse.cz> - 2017-03-19 11:20 +0100
        Re: [RFC 2/2] fanotify: emit FAN_MODIFY_DIR on filesystem changes Filip Štědronský <r.lkml@regnarg.cz> - 2017-03-19 11:50 +0100
          Re: [RFC 2/2] fanotify: emit FAN_MODIFY_DIR on filesystem changes Jan Kara <jack@suse.cz> - 2017-03-20 12:20 +0100
            Re: [RFC 2/2] fanotify: emit FAN_MODIFY_DIR on filesystem changes Amir Goldstein <amir73il@gmail.com> - 2017-03-20 12:50 +0100
            Re: [RFC 2/2] fanotify: emit FAN_MODIFY_DIR on filesystem changes Filip Štědronský <r.lkml@regnarg.cz> - 2017-03-20 13:00 +0100
        Re: [RFC 2/2] fanotify: emit FAN_MODIFY_DIR on filesystem changes bfields@fieldses.org (J. Bruce Fields) - 2017-03-21 16:50 +0100
          Re: [RFC 2/2] fanotify: emit FAN_MODIFY_DIR on filesystem changes Jan Kara <jack@suse.cz> - 2017-03-21 17:50 +0100
            Re: [RFC 2/2] fanotify: emit FAN_MODIFY_DIR on filesystem changes "J. Bruce Fields" <bfields@fieldses.org> - 2017-03-21 18:50 +0100
  Re: [RFC 1/2] fanotify: new event FAN_MODIFY_DIR Amir Goldstein <amir73il@gmail.com> - 2017-03-14 11:20 +0100
    Re: [RFC 1/2] fanotify: new event FAN_MODIFY_DIR Filip Štědronský <r.lkml@regnarg.cz> - 2017-03-14 13:50 +0100
      Re: [RFC 1/2] fanotify: new event FAN_MODIFY_DIR Amir Goldstein <amir73il@gmail.com> - 2017-03-14 15:00 +0100
        Re: [RFC 1/2] fanotify: new event FAN_MODIFY_DIR Filip Štědronský <r.lkml@regnarg.cz> - 2017-03-14 16:00 +0100
          Re: [RFC 1/2] fanotify: new event FAN_MODIFY_DIR Amir Goldstein <amir73il@gmail.com> - 2017-03-14 23:40 +0100
    Re: [RFC 1/2] fanotify: new event FAN_MODIFY_DIR Jan Kara <jack@suse.cz> - 2017-03-15 15:10 +0100
      Re: [RFC 1/2] fanotify: new event FAN_MODIFY_DIR Amir Goldstein <amir73il@gmail.com> - 2017-03-15 15:40 +0100
        Re: [RFC 1/2] fanotify: new event FAN_MODIFY_DIR Jan Kara <jack@suse.cz> - 2017-03-16 11:40 +0100
  Re: [RFC 1/2] fanotify: new event FAN_MODIFY_DIR Michael Kerrisk <mtk.manpages@gmail.com> - 2017-03-15 06:00 +0100

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