Re: [PATCH 1/1] rosebush: Add new data structure

[Al Viro <viro@kernel.org>]

On Thu, Feb 22, 2024 at 08:37:24PM +0000, Matthew Wilcox (Oracle) wrote:
> Rosebush is a resizing hash table.  See
> Docuemntation/core-api/rosebush.rst for details.

Interesting...  A few obvious questions wrt dcache:
	* how do the locks that stuff nest wrt ->d_lock?  Inside?
	* same for rename_lock (on rename dentries change names/parents/hash
values).
	* we would be really forced to maintain DCACHE_UNHASHED in ->d_flags;
it's not impossible to do, but will take care (protection of ->d_flags has
several dark corners).
	* the cost of d_drop() goes up.  Might or might not get painful.
	* if the bucket locks nest inside ->d_lock, we'd better look out
for the latter getting held for longer.  Might get unpleasant.