On Thu, May 23, 2024 at 11:44:05AM -0400, Mike Snitzer wrote:
> a difference on larger IOs being formed (given it is virtual
> scsi_debug devices).
>
> In any case, we know I can reproduce with this scsi_debug-based mptest
> test and Marco has verified my fix resolves the issue on his FC
> multipath testbed.
>
> But I've just floated a patch to elevate the fix to block core (based
> on Ming's suggestion):
> https://patchwork.kernel.org/project/dm-devel/patch/[email protected]/
I still think that is wrong. Unfortunately I can't actually reproduce
the issue locally, but I think we want sd to set the user_max_sectors
and stack if you want to see the limits propagated, i.e. the combined
patch below. In the longer run I need to get SCSI out of messing
with max_sectors directly, and the blk-mq stacking to stop looking
at it vs just the hardware limits (or just drop the check).
diff --git a/block/blk-settings.c b/block/blk-settings.c
index a7fe8e90240a6e..7a672021daee6a 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -611,6 +611,8 @@ int blk_stack_limits(struct queue_limits *t, struct
queue_limits *b,
unsigned int top, bottom, alignment, ret = 0;
t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors);
+ t->max_user_sectors = min_not_zero(t->max_user_sectors,
+ b->max_user_sectors);
t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors);
t->max_dev_sectors = min_not_zero(t->max_dev_sectors,
b->max_dev_sectors);
t->max_write_zeroes_sectors = min(t->max_write_zeroes_sectors,
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 332eb9dac22d91..f6c822c9cbd2d3 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3700,8 +3700,10 @@ static int sd_revalidate_disk(struct gendisk *disk)
*/
if (sdkp->first_scan ||
q->limits.max_sectors > q->limits.max_dev_sectors ||
- q->limits.max_sectors > q->limits.max_hw_sectors)
+ q->limits.max_sectors > q->limits.max_hw_sectors) {
q->limits.max_sectors = rw_max;
+ q->limits.max_user_sectors = rw_max;
+ }
sdkp->first_scan = 0;
