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

[Damien Le Moal <damien.lemoal@opensource.wdc.com>]

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;
-- 
2.37.3