anon_inode: rework assertions

Making anonymous inodes regular files comes with a lot of risk and
regression potential as evidenced by a recent hickup in io_uring. We're
better of continuing to not have them be regular files. Since we have
S_ANON_INODE we can port all of our assertions easily.

Fixes: cfd86ef7e8e7 ("anon_inode: use a proper mode internally")
Cc: <stable@kernel.org>
Reported-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>
3 files changed