> 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