On 4/29/25 17:29, Aaron Lu wrote:
> Ever since commit eca2040972b4("scsi: block: ioprio: Clean up interface
> definition"), the io priority level is masked and can no longer be larger
> than IOPRIO_NR_LEVELS so remove this now useless test.
>
> The actual test of io prio level is done in ioprio_value() where any
> invalid input of class/level/hint will result in an invalid class being
> passed to the syscall, this is introduced in commit 01584c1e2337("scsi:
> block: Improve ioprio value validity checks").
>
> Reported-by: Kexin Wei <ys.weikexin@xxxxxxx>
> Cc: Damien Le Moal <dlemoal@xxxxxxxxxx>
> Signed-off-by: Aaron Lu <ziqianlu@xxxxxxxxxxxxx>
> ---
> Kexin reported a LTP/ioprio_set03 case failure, where the test would
> pass IOPRIO_CLASS_BE with priority level 8 and see if kernel would
> return error. Turned out she is using an old kernel header where the
> change introduced in commit 01584c1e2337("scsi: block: Improve ioprio
> value validity checks") isn't available. During troubleshooting, I find
> this priority level test confusing and misleading so I think it should
> be removed.
What is confusing and misleading about the fact that we support only 8 priority
levels (0 to 7) and should check for it ?
With that said, the test is indeed redundant for the BE and RT class because we
have:
int ioprio_check_cap(int ioprio)
{
int class = IOPRIO_PRIO_CLASS(ioprio);
int level = IOPRIO_PRIO_LEVEL(ioprio);
And the macro IOPRIO_PRIO_LEVEL() will mask the level value to something between
0 and 7, always. So necessarily, level will always be lower than
IOPRIO_NR_LEVELS. So please reword your commit message to explain that rather
than describe what a user may or may not use when setting an ioprio field.
And also simplify the patch:
diff --git a/block/ioprio.c b/block/ioprio.c
index 73301a261429..f0ee2798539c 100644
--- a/block/ioprio.c
+++ b/block/ioprio.c
@@ -46,12 +46,8 @@ int ioprio_check_cap(int ioprio)
*/
if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_NICE))
return -EPERM;
- fallthrough;
- /* rt has prio field too */
- case IOPRIO_CLASS_BE:
- if (level >= IOPRIO_NR_LEVELS)
- return -EINVAL;
break;
+ case IOPRIO_CLASS_BE:
case IOPRIO_CLASS_IDLE:
break;
case IOPRIO_CLASS_NONE:
> block/ioprio.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/block/ioprio.c b/block/ioprio.c
> index 73301a261429f..60364d3faf800 100644
> --- a/block/ioprio.c
> +++ b/block/ioprio.c
> @@ -46,11 +46,8 @@ int ioprio_check_cap(int ioprio)
> */
> if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_NICE))
> return -EPERM;
> - fallthrough;
> - /* rt has prio field too */
> + break;
> case IOPRIO_CLASS_BE:
> - if (level >= IOPRIO_NR_LEVELS)
> - return -EINVAL;
> break;
> case IOPRIO_CLASS_IDLE:
> break;
--
Damien Le Moal
Western Digital Research
