Revert "ovl: do not encode lower fh with upper sb_writers held"

This reverts commit 26423e18 which is
commit 5b02bfc1 upstream.

It is reported to part of a series that causes problems in the 6.6.y
tree, so revert it at this point in time and it can come back later if
still needed.

Reported-by: Ignat Korchagin <ignat@cloudflare.com>
Link: https://lore.kernel.org/r/ACD4D6CC-C4D5-4657-A805-03C34559046E@cloudflare.com


Cc: Dmitry Safonov <dima@arista.com>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>