[PATCH 2/2] s390/dasd: Establish DMA alignment

[Stefan Haberland <sth@linux.ibm.com>]

From: Eric Farman <farman@linux.ibm.com>

linux-next commit bf8d08532bc1 ("iomap: add support for dma aligned
direct-io") changes the alignment requirement to come from the block
device rather than the block size, and the default alignment
requirement is 512-byte boundaries. Since DASD I/O has page
alignments for IDAW/TIDAW requests, let's override this value to
restore the expected behavior.

Make this change for both ECKD and DIAG disciplines, as they both
would fall into this category. Leave FBA alone, since it is always
comprised of 512-byte blocks.

Signed-off-by: Eric Farman <farman@linux.ibm.com>
Acked-by: Halil Pasic <pasic@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
---
 drivers/s390/block/dasd_diag.c | 1 +
 drivers/s390/block/dasd_eckd.c | 1 +
 2 files changed, 2 insertions(+)

diff --git a/drivers/s390/block/dasd_diag.c b/drivers/s390/block/dasd_diag.c
index e9edf3b6ed7c..94ee59864971 100644
--- a/drivers/s390/block/dasd_diag.c
+++ b/drivers/s390/block/dasd_diag.c
@@ -639,6 +639,7 @@ static void dasd_diag_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);
 }
 
 static int dasd_diag_pe_handler(struct dasd_device *device,
diff --git a/drivers/s390/block/dasd_eckd.c b/drivers/s390/block/dasd_eckd.c
index 836838f7d686..3cc93e2e4e15 100644
--- a/drivers/s390/block/dasd_eckd.c
+++ b/drivers/s390/block/dasd_eckd.c
@@ -6626,6 +6626,7 @@ static void dasd_eckd_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);
 }
 
 static struct ccw_driver dasd_eckd_driver = {
-- 
2.34.1