[PATCH v2] nvme: Fix io_opt limit setting

[PATCH v2] nvme: Fix io_opt limit setting

[Damien Le Moal]

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>
---

* Changes from v1:
  - Rebased on nvme/nvme-5.8 tree

 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 805d289e6cd9..951d558dc662 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1842,7 +1842,7 @@ 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 */
@@ -1851,7 +1851,7 @@ 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) {
 		/*
-- 
2.25.4


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Re: [PATCH v2] nvme: Fix io_opt limit setting

[Hannes Reinecke]

On 5/14/20 7:56 AM, Damien Le Moal wrote:
> 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>
> ---
> 
> * Changes from v1:
>    - Rebased on nvme/nvme-5.8 tree
> 
>   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 805d289e6cd9..951d558dc662 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -1842,7 +1842,7 @@ 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 */
> @@ -1851,7 +1851,7 @@ 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) {
>   		/*
> 
Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke            Teamlead Storage & Networking
hare@suse.de                               +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer

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Re: [PATCH v2] nvme: Fix io_opt limit setting

[Bart Van Assche]

On 2020-05-13 22:56, Damien Le Moal wrote:
> 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:

Reviewed-by: Bart van Assche <bvanassche@acm.org>

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Re: [PATCH v2] nvme: Fix io_opt limit setting

[Christoph Hellwig]

Thanks,

applied to nvme-5.8.

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Re: [PATCH v2] nvme: Fix io_opt limit setting

[Martin K. Petersen]

Damien,

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

I'm also OK with this approach.

Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>

-- 
Martin K. Petersen	Oracle Linux Engineering

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