Re: [PATCH v3 12/24] erofs: introduce tagged pointer

From: Amir Goldstein
Date: Mon Jul 22 2019 - 00:39:49 EST

On Mon, Jul 22, 2019 at 5:54 AM Gao Xiang <gaoxiang25@xxxxxxxxxx> wrote:
> Currently kernel has scattered tagged pointer usages
> hacked by hand in plain code, without a unique and
> portable functionset to highlight the tagged pointer
> itself and wrap these hacked code in order to clean up
> all over meaningless magic masks.
> This patch introduces simple generic methods to fold
> tags into a pointer integer. Currently it supports
> the last n bits of the pointer for tags, which can be
> selected by users.
> In addition, it will also be used for the upcoming EROFS
> filesystem, which heavily uses tagged pointer pproach
> to reduce extra memory allocation.
> Link:

Well, it won't do much good for other kernel users in fs/erofs/ ;-)

I think now would be a right time to promote this facility to
include/linux as you initially proposed.
I don't recall you got any objections. No ACKs either, but I think
that was the good kind of silence (?)

You might want to post the __fdget conversion patch [1] as a
bonus patch on top of your series.