[PATCHv4 1/2] dm: initialize dma_alignment to 0

[Keith Busch <kbusch@meta.com>]

From: Keith Busch <kbusch@kernel.org>

All device mappers that want to override the dma_alignment do so.
However, because the default stacking limit is set to 511, a device
mapper couldn't make it smaller even if it is capable of handling
finer grained alignment.

Set the default dm stacking dma_alignment limit to 0 so that it can be
stacked with any value a device mapper wants. If a mapper doesn't
override the value, the initial 0 value will get changed to the original
default 511 value when the limits are validated after the device
stacking is complete.

Signed-off-by: Keith Busch <kbusch@kernel.org>
---
 drivers/md/dm-table.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index dc2eff6b739df..80326f8096cb7 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -591,6 +591,7 @@ static void dm_set_stacking_limits(struct queue_limits *limits)
 {
 	blk_set_stacking_limits(limits);
 	limits->features |= BLK_FEAT_IO_STAT | BLK_FEAT_NOWAIT | BLK_FEAT_POLL;
+	limits->dma_alignment = 0;
 }
 
 /*
-- 
2.52.0