Commit b224f613 authored Nov 24, 2017 by David Disseldorp Committed by Christoph Hellwig Dec 15, 2017

nvme: set discard_alignment to zero



Similar to 7c084289 ("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>

parent fcf38cdf

drivers/nvme/host/core.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1287,7 +1287,7 @@ static void nvme_config_discard(struct nvme_ctrl *ctrl,
		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);

Admin message