Re: [PATCH v2] md/raid0: add config parameters to specify zone layout

[Song Liu]

> On Mar 30, 2020, at 9:00 AM, Jason Baron <jbaron@xxxxxxxxxx> wrote:
> 
> Let's add some CONFIG_* options to directly configure the raid0 layout
> if you know in advance how your raid0 array was created. This can be
> simpler than having to manage module or kernel command-line parameters.
> 
> If the raid0 array was created by a pre-3.14 kernel, use
> RAID0_ORIG_LAYOUT. If the raid0 array was created by a 3.14 or newer
> kernel then select RAID0_ALT_MULTIZONE_LAYOUT. Otherwise, the default
> setting is RAID0_LAYOUT_NONE, in which case the current behavior of
> needing to specify a module parameter raid0.default_layout=1|2 is
> preserved.
> 
> Cc: Guoqing Jiang <guoqing.jiang@xxxxxxxxxxxxxxx>
> Cc: NeilBrown <neilb@xxxxxxx>
> Cc: Song Liu <songliubraving@xxxxxx>
> Signed-off-by: Jason Baron <jbaron@xxxxxxxxxx>

This patch looks good. However, I am not sure whether the user will 
recompile the kernel for a different default value. Do you have real
world use case for this?

Thanks,
Song