Re: [PATCH] nvme: Fix io_opt limit setting

[Hannes Reinecke <hare@suse.de>]

On 5/14/20 3:54 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 this value. 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;
> }
> 
> results in blk_stack_limits() to return an error 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 optiomal IO size limit if the namespace does
> not report an optimal write size value.
> 
> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
> ---
>   drivers/nvme/host/core.c | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)
> 
Ah, so you beat me to it :-)

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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