On 10/21/22 17:45, Hannes Reinecke wrote: > On 10/21/22 10:00, Damien Le Moal wrote: >> On 10/21/22 15:50, Damien Le Moal wrote: >>> On 10/21/22 15:21, Hannes Reinecke wrote: >>>> On 10/21/22 07:38, Damien Le Moal wrote: >>>>> From: "Maciej S. Szmigiero" <maciej.szmigiero@xxxxxxxxxx> >>>>> >>>>> 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@xxxxxxxxxx> >>>>> Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx> >>>>> --- >>>>> 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. >>> >>> Well, this is not sysfs, we cannot do this automatically easily... >>> And thinking about it now that you mention it, going from fua=1 to fua=0 >>> can actually cause problems. The reverse not, since scsi side would still >>> see fua=0 until revalidation. >>> >>> So... Unless we find a way to link the param write to reavlidation, we >>> should actually not allow this. >>> Maciej ? Thoughts ? >> >> I looked at this a little more. We could define the operations (struct >> kernel_param_ops) manually together with the fua parameter declaration, >> but that would be really ugly... >> >> Given that we are switching to fua=1 by default, do you still need a >> dynamic argument ? I am now thinking that this patch should be dropped. >> > I'd kill it, and let users it handle via blacklist flags only. Yep, with the default set to 1 that is the goal. I kept the fua module parameter for backward compatibility, in case some setups out there use it. But the force=[ID]nofua or force=[ID]fua module parameters should be the preferred way to control this now. > > Cheers, > > Hannes -- Damien Le Moal Western Digital Research
