ovl: inherit FMODE_NONOTIFY when opening directory realfiles

When fanotify hands a listener an fd for a permission event on an
overlay directory, ovl_dir_open_realfile() opens the real directory via
dentry_open(), not backing_file_open(), so the lower open could still
raise FS_OPEN_PERM and deadlock a listener that also marks the backing
filesystem.

Export dentry_open_nonotify() and call it from ovl_path_open_realfile()
when the overlay user file must not generate events.  Ordinary
ovl_path_open() callers are unchanged.

Reported-by: Christian Brauner (Amutable) <brauner@kernel.org>
Closes: https://lore.kernel.org/all/20261030-welpen-anbinden-nullen-b2432cee1d10@brauner/
Fixes: 130fdbc3d1f99 ("ovl: pass correct flags for opening real directory")
Cc: stable@vger.kernel.org
Tested-by: Edvard Conrad <edvard@tuta.io>
Link: https://lore.kernel.org/ltp/P5Iny41--F-9@tuta.io/
Signed-off-by: Amir Goldstein <amir73il@gmail.com>

0 files changed, 0 insertions, 0 deletions