linux-kernel - [PATCH 1/2] ata: allow toggling fua parameter at runtime

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Date:   Mon, 26 Sep 2022 21:51:42 +0200
From:   "Maciej S. Szmigiero" <mail@...iej.szmigiero.name>
To:     Damien Le Moal <damien.lemoal@...nsource.wdc.com>
Cc:     linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] ata: allow toggling fua parameter at runtime

From: "Maciej S. Szmigiero" <maciej.szmigiero@...cle.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

Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@...cle.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 75b86913db1ac..b322006c85806 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;