On Fri, Dec 13, 2019 at 11:36:25AM -0700, Jens Axboe wrote: > If the fast lookup fails, then return -EAGAIN to have the caller retry > the path lookup. This is in preparation for supporting non-blocking > open. NAK. We are not littering fs/namei.c with incremental broken bits and pieces with uncertain eventual use. And it's broken - lookup_slow() is *NOT* the only place that can and does block. For starters, ->d_revalidate() can very well block and it is called outside of lookup_slow(). So does ->d_automount(). So does ->d_manage(). I'm rather sceptical about the usefulness of non-blocking open, to be honest, but in any case, one thing that is absolutely not going to happen is piecewise introduction of such stuff without a discussion of the entire design.
