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From: Mo Re Ra <>
To: Amir Goldstein <>
Cc: Jan Kara <>, linux-fsdevel <>
Subject: Re: File monitor problem
Date: Wed, 4 Dec 2019 17:54:48 +0330
Message-ID: <> (raw)
In-Reply-To: <>

On Wed, Dec 4, 2019 at 4:23 PM Amir Goldstein <> wrote:
> On Wed, Dec 4, 2019 at 12:03 PM Mo Re Ra <> wrote:
> >
> > Hi,
> >
> > I don`t know if this is the correct place to express my issue or not.
> > I have a big problem. For my project, a Directory Monitor, I`ve
> > researched about dnotify, inotify and fanotify.
> > dnotify is the worst choice.
> > inotify is a good choice but has a problem. It does not work
> > recursively. When you implement this feature by inotify, you would
> > miss immediately events after subdir creation.
> > fanotify is the last choice. It has a big change since Kernel 5.1. But
> > It does not meet my requirement.
> >
> > I need to monitor a directory with CREATE, DELETE, MOVE_TO, MOVE_FROM
> > and CLOSE_WRITE events would be happened in its subdirectories.
> > Filename of the events happened on that (without any miss) is
> > mandatory for me.
> >
> > I`ve searched and found a contribution from @amiril73 which
> > unfortunately has not been merged. Here is the link:
> >
> >
> > I`d really appreciate it If you could resolve this issue.
> >
> Hi Mohammad,
> Thanks for taking an interest in fanotify.
> Can you please elaborate about why filename in events are mandatory
> for your application.
> Could your application use the FID in FAN_DELETE_SELF and
> FAN_MOVE_SELF events to act on file deletion/rename instead of filename
> information in FAN_DELETE/FAN_MOVED_xxx events?
> Will it help if you could get a FAN_CREATE_SELF event with FID information
> of created file?
> Note that it is NOT guarantied that your application will be able to resolve
> those FID to file path, for example if file was already deleted and no open
> handles for this file exist or if file has a hardlink, you may resolve the path
> of that hardlink instead.
> Jan,
> I remember we discussed the optional FAN_REPORT_FILENAME [1] and
> you had some reservations, but I am not sure how strong they were.
> Please refresh my memory.
> Thanks,
> Amir.
> [1]

Hi Amir,
Thanks for your attention.

Fanotify project had a big change since Kernel 5.1 but did not meet
some primiry needs.
For example in my application, I`m watching on a specific directory to
sync it (through a socket connection and considering some policies)
with a directory in a remote system which a user working on that. Some
subdirectoires may contain two milions of files or more. I need these
two directoires be synced completely as soon as possible without any
missed notification.
So, I need a syscall with complete set of flags to help to watch on a
directory and all of its subdirectories recuresively without any
missed notification.

Unfortuantely, in current version of Fanotify, the notification just
expresses a change has been occured in a directory but dot not
specifiy which file! I could not iterate over millions of file to
determine which file was that. That would not be helpful.

Inevitably, xxx_SELF would not help me to meets all I need. Just to
clarify, I dont mean xxx_SELF flags are useless. I mean Fanotify is a
good project but the current version of that is not a project which
meets some basic needs.

Mohammad Reza.

  reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-04 10:02 Mo Re Ra
2019-12-04 12:53 ` Amir Goldstein
2019-12-04 14:24   ` Mo Re Ra [this message]
2019-12-04 17:34     ` Jan Kara
2019-12-04 18:37       ` Amir Goldstein
2019-12-04 19:02         ` Matthew Wilcox
2019-12-04 20:27           ` Amir Goldstein
2019-12-11 10:06             ` Jan Kara
2019-12-11 13:58               ` Amir Goldstein
2019-12-07 12:36       ` Mo Re Ra
2019-12-10 16:55         ` Jan Kara
2019-12-10 20:49           ` Amir Goldstein

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