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From:   Amir Goldstein <amir73il@gmail.com>
Date:   Mon, 22 Jul 2019 07:39:27 +0300
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Subject: Re: [PATCH v3 12/24] erofs: introduce tagged pointer
To:     Gao Xiang <gaoxiang25@huawei.com>
Cc:     Alexander Viro <viro@zeniv.linux.org.uk>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        "Theodore Ts'o" <tytso@mit.edu>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        devel@driverdev.osuosl.org, LKML <linux-kernel@vger.kernel.org>,
        linux-erofs@lists.ozlabs.org, Chao Yu <yuchao0@huawei.com>,
        Miao Xie <miaoxie@huawei.com>,
        Li Guifu <bluce.liguifu@huawei.com>,
        Fang Wei <fangwei1@huawei.com>
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On Mon, Jul 22, 2019 at 5:54 AM Gao Xiang <gaoxiang25@huawei.com> 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: https://en.wikipedia.org/wiki/Tagged_pointer

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.

Thanks,
Amir.

[1] https://lore.kernel.org/linux-fsdevel/1530543233-65279-2-git-send-email-gaoxiang25@huawei.com/