Subject: bug#66381: 29.1; Auto-revert not polling files when notifications are enabled

From: Daniel Jacobowitz <[email-masked]>
Date: Mon, 9 Oct 2023 14:17:17 -0400

Thanks for the follow-up!

First of all, for anyone who stumbles on this, inotifywait's
documentation says it listens to all events by default. But it doesn't
request IN_UNMOUNT unless you use `-e unmount`. That confused all of
my test results - that's why I thought the event was never generated.
In possession of this new knowledge, I verified that an unmount event
is delivered to inotifywait when my filesystem daemon restarts. So
that's great progress.

I built a patched emacs and tried unmounting the filesystem. Emacs was notified:

file-notify-handle-event (file-notify ((1 . 0) (unmount isdir)
"/google/src/cloud/dmj/emacs/google3" 0)
file-notify--callback-inotify)
file-notify-handle-event (file-notify ((1 . 0) stopped
"/google/src/cloud/dmj/emacs/google3/file.txt")
auto-revert-notify-handler)
auto-revert-notify-handler ((1 . 0) stopped
"/google/src/cloud/dmj/emacs/google3/file.txt")
file-notify-handle-event (file-notify ((1 . 0) stopped
"/google/src/cloud/dmj/emacs/google3/file.txt")
auto-revert-notify-handler)
auto-revert-notify-handler ((1 . 0) stopped
"/google/src/cloud/dmj/emacs/google3/file.txt")
file-notify-handle-event (file-notify ((1 . 0) (ignored)
"/google/src/cloud/dmj/emacs/google3" 0)
file-notify--callback-inotify)

It works! Thanks!

On Sun, Oct 8, 2023 at 8:38 AM Michael Albinus <[email-masked]> wrote:
>
> Michael Albinus <[email-masked]> writes:
>
> Hi,
>
> > The problem is, that in Daniel's case we get no information that file
> > notification has ceased to work for the re-mounted file system (no
> > IN_IGNORED event from inotify). auto-revert-notify-watch-descriptor
> > still exists, and auto-revert-notify-modified-p isn't modified any
> > longer. Therefore the file is not reverted even while polling.
>
> I've debugged further, and it looks like there is a gap in forwarding
> the IN_IGNORED event from inotify.c to filenotify.el. Oops.
>
> Daniel, could you pls try the appended patch? It shall enable this to
> work, meaning auto-revert-mode is informed about the unmounted file
> system. I've tested with an NFS mount, 'tho.
>
> Best regards, Michael.
>

-- 
Thanks,
Daniel