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From: Damien Le Moal <damien.lemoal@wdc.com>
Date: Thu, 14 May 2020 14:56:26 +0900
Subject: [PATCH] nvme: fix io_opt limit setting
Git-commit: 68ab60ca2d6bd8e6b1ecc2857a174c1c2b9451e9
Patch-mainline: v5.8-rc1
References: jsc#SLE-15608

Currently, a namespace io_opt queue limit is set by default to the
physical sector size of the namespace and to the the write optimal
size (NOWS) when the namespace reports optimal IO sizes. This causes
problems with block limits stacking in blk_stack_limits() when a
namespace block device is combined with an HDD which generally do not
report any optimal transfer size (io_opt limit is 0). The code:

/* Optimal I/O a multiple of the physical block size? */
if (t->io_opt & (t->physical_block_size - 1)) {
	t->io_opt = 0;
	t->misaligned = 1;
	ret = -1;
}

in blk_stack_limits() results in an error return for this function when
the combined devices have different but compatible physical sector
sizes (e.g. 512B sector SSD with 4KB sector disks).

Fix this by not setting the optimal IO size queue limit if the namespace
does not report an optimal write size value.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Bart van Assche <bvanassche@acm.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Hannes Reinecke <hare@suse.com>
---
 drivers/nvme/host/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 43a6336d6264..4c194dcabd12 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1845,7 +1845,7 @@ static void nvme_update_disk_info(struct gendisk *disk,
 {
 	sector_t capacity = nvme_lba_to_sect(ns, le64_to_cpu(id->nsze));
 	unsigned short bs = 1 << ns->lba_shift;
-	u32 atomic_bs, phys_bs, io_opt;
+	u32 atomic_bs, phys_bs, io_opt = 0;
 
 	if (ns->lba_shift > PAGE_SHIFT) {
 		/* unsupported block size, set capacity to 0 later */
@@ -1854,7 +1854,7 @@ static void nvme_update_disk_info(struct gendisk *disk,
 	blk_mq_freeze_queue(disk->queue);
 	blk_integrity_unregister(disk);
 
-	atomic_bs = phys_bs = io_opt = bs;
+	atomic_bs = phys_bs = bs;
 	nvme_setup_streams_ns(ns->ctrl, ns, &phys_bs, &io_opt);
 	if (id->nabo == 0) {
 		/*
-- 
2.16.4