Re: [PATCH 2/4] introduce four macros for in-kernel hints

From: "Javier González" <javier@javigon.com>
To: Kanchan Joshi <joshi.k@samsung.com>
Cc: linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org,
	linux-ext4@vger.kernel.org, linux-nvme@lists.infradead.org,
	jack@suse.com, david@fromorbit.com, tytso@mit.edu,
	prakash.v@samsung.com
Subject: Re: [PATCH 2/4] introduce four macros for in-kernel hints
Date: Wed, 23 Jan 2019 19:27:12 +0100	[thread overview]
Message-ID: <B4980620-2CFF-41C1-8EE7-C33F1FE431C0@javigon.com> (raw)
In-Reply-To: <1547047861-7271-3-git-send-email-joshi.k@samsung.com>

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> On 9 Jan 2019, at 16.30, Kanchan Joshi <joshi.k@samsung.com> wrote:
> 
> Exiting write-hints are exposed to user-mode. There is a possiblity
> of conflict if kernel happens to use those. This patch introduces four
> write-hints for exclusive kernel-mode use.
> 
> Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
> ---
> include/linux/fs.h | 5 +++++
> 1 file changed, 5 insertions(+)
> 
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 811c777..e8548eb 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -291,6 +291,11 @@ enum rw_hint {
> 	WRITE_LIFE_MEDIUM	= RWH_WRITE_LIFE_MEDIUM,
> 	WRITE_LIFE_LONG		= RWH_WRITE_LIFE_LONG,
> 	WRITE_LIFE_EXTREME	= RWH_WRITE_LIFE_EXTREME,
> +/* below ones are meant for in-kernel use */
> +	KERN_WRITE_LIFE_SHORT,
> +	KERN_WRITE_LIFE_MEDIUM,
> +	KERN_WRITE_LIFE_LONG,
> +	KERN_WRITE_LIFE_EXTREME
> };
> 

I think Jens and Dave meant kernel hints to go top down. This would also
give space for supporting more hints / streams from both ends for user
and kernel.

Javier

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