CCing Stefan, Jan.
Below is necessary (in dasd-eckd.c) to make kvm boot working again (and this seems to be the right thing anyway).
Am 29.06.22 um 21:07 schrieb Keith Busch:
On Wed, Jun 29, 2022 at 02:04:47PM -0400, Eric Farman wrote:
s390 dasd
This made me think to change my rootfs, and of course the problem goes
away once on something like a SCSI volume.
So crawling through the dasd (instead of virtio) driver and I finally
find the point where a change to dma_alignment (which you mentioned
earlier) would actually fit.
Such a change fixes this for me, so I'll run it by our DASD guys.
Thanks for your help and patience.
I'm assuming there's some driver or device requirement that's making this
necessary. Is the below driver change what you're looking for? If so, I think
you might want this regardless of this direct-io patch just because other
interfaces like blk_rq_map_user_iov() and blk_rq_aligned() align to it.
---
diff --git a/drivers/s390/block/dasd_fba.c b/drivers/s390/block/dasd_fba.c
index 60be7f7bf2d1..5c79fb02cded 100644
--- a/drivers/s390/block/dasd_fba.c
+++ b/drivers/s390/block/dasd_fba.c
@@ -780,6 +780,7 @@ static void dasd_fba_setup_blk_queue(struct dasd_block *block)
/* With page sized segments each segment can be translated into one idaw/tidaw */
blk_queue_max_segment_size(q, PAGE_SIZE);
blk_queue_segment_boundary(q, PAGE_SIZE - 1);
+ blk_queue_dma_alignment(q, PAGE_SIZE - 1);
q->limits.discard_granularity = logical_block_size;
--
