Re: [PATCH 2/3] ata: libata: allow toggling fua parameter at runtime

From: Hannes Reinecke <hare@suse.de>
To: Damien Le Moal <damien.lemoal@opensource.wdc.com>,
	linux-ide@vger.kernel.org,
	"Maciej S . Szmigiero" <mail@maciej.szmigiero.name>
Subject: Re: [PATCH 2/3] ata: libata: allow toggling fua parameter at runtime
Date: Fri, 21 Oct 2022 08:21:22 +0200	[thread overview]
Message-ID: <c1fc6322-d6d4-4579-1281-130e0546883b@suse.de> (raw)
In-Reply-To: <20221021053809.237651-3-damien.lemoal@opensource.wdc.com>

On 10/21/22 07:38, Damien Le Moal wrote:
> From: "Maciej S. Szmigiero" <maciej.szmigiero@oracle.com>
> 
> Currently, the libata.fua parameter isn't runtime-writable, so a
> system restart is required in order to toggle it.
> This unnecessarily complicates testing how drives behave with FUA on and
> off.
> 
> Let's make this parameter R/W instead, like many others in the kernel.
> 
> Example usage:
> Disable the parameter:
> echo 0 >/sys/module/libata/parameters/fua
> 
> Revalidate disk cache settings:
> F=/sys/class/scsi_disk/0\:0\:0\:0/cache_type; echo `cat $F` >$F
> 
> [Damien]
> Enabling fua support by setting libata.fua to 1 will have no effect if
> the libata module is loaded with libata.force=[ID]nofua, which disables
> fua support for the ata device(s) identified with ID or all ata devices
> if no ID is specified.
> 
> Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
> Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
> ---
>   drivers/ata/libata-core.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
> index 6008f7ed1c42..1bb9616b10d9 100644
> --- a/drivers/ata/libata-core.c
> +++ b/drivers/ata/libata-core.c
> @@ -128,7 +128,7 @@ module_param(atapi_passthru16, int, 0444);
>   MODULE_PARM_DESC(atapi_passthru16, "Enable ATA_16 passthru for ATAPI devices (0=off, 1=on [default])");
>   
>   int libata_fua = 0;
> -module_param_named(fua, libata_fua, int, 0444);
> +module_param_named(fua, libata_fua, int, 0644);
>   MODULE_PARM_DESC(fua, "FUA support (0=off [default], 1=on)");
>   
>   static int ata_ignore_hpa;
Hmm. I guess you'll need to revalidate the drive when changing that; but 
this can be done in a later patch.

Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare@suse.de                              +49 911 74053 688
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