Re: [RFC][PATCH 1/2] fanotify: add support for FAN_UNMOUNT event

On Fri, Apr 14, 2023 at 09:29:02PM +0300, Amir Goldstein wrote:

inotify generates unsolicited IN_UNMOUNT events for every inode
mark before the filesystem containing the inode is shutdown.

Unlike IN_UNMOUNT, FAN_UNMOUNT is an opt-in event that can only be
set on a mount mark and is generated when the mount is unmounted.

FAN_UNMOUNT requires FAN_REPORT_FID and reports an fid info record
with fsid of the filesystem and an empty file handle.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
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I think this is a useful addition to the fanotify api and more useful
than IN_UMOUNT.

Going back to your cover letter. Afaiu, IN_UMOUNT is generated when the
superblock in which a watched object resides goes away. That's roughly
what I had in mind with FAN_SB_SHUTDOWN (ignoring naming discusions for
now).