From: David Disseldorp <ddiss@suse.de>
Date: Fri, 24 Nov 2017 16:30:53 +0100
Subject: nvme: set discard_alignment to zero
Patch-mainline: v4.15-rc5
Git-commit: b224f6134d72e3493a023b5bea917f9a6beea0c8
References: FATE#323952, FATE#322506

Similar to 7c084289795b ("rbd: set discard_alignment to zero"), NVMe
devices are currently incorrectly initialised with the block queue
discard_alignment set to the NVMe stream alignment.

As per Documentation/ABI/testing/sysfs-block:
  The discard_alignment parameter indicates how many bytes the beginning
  of the device is offset from the internal allocation unit's natural
  alignment.

Correcting the discard_alignment parameter to zero has no effect on how
discard requests are propagated through the block layer - @alignment in
__blkdev_issue_discard() remains zero. However, it does fix other
consumers, such as LIO's Block Limits VPD response.

Signed-off-by: David Disseldorp <ddiss@suse.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Johannes Thumshirn <jthumshirn@suse.de>
---
 drivers/nvme/host/core.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1287,7 +1287,7 @@ static void nvme_config_discard(struct n
 	BUILD_BUG_ON(PAGE_SIZE / sizeof(struct nvme_dsm_range) <
 			NVME_DSM_MAX_RANGES);
 
-	queue->limits.discard_alignment = size;
+	queue->limits.discard_alignment = 0;
 	queue->limits.discard_granularity = size;
 
 	blk_queue_max_discard_sectors(queue, UINT_MAX);