Re: [PATCH 2/2] nvme-multipath: do not fall back to __nvme_find_path() for non-optimized paths

[Hannes Reinecke <hare@suse.de>]

On 7/27/20 9:46 PM, Sagi Grimberg wrote:
> 
> 
> On 7/27/20 9:08 AM, Hannes Reinecke wrote:
>> When nvme_round_robin_path() finds a valid namespace we should be 
>> using it;
>> falling back to __nvme_find_path() for non-optimized paths will cause the
>> result from nvme_round_robin_path() to be ignored for non-optimized 
>> paths.
>>
>> Signed-off-by: Martin Wilck <mwilck@suse.com>
>> Signed-off-by: Hannes Reinecke <hare@suse.de>
>> ---
>>   drivers/nvme/host/multipath.c | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/nvme/host/multipath.c 
>> b/drivers/nvme/host/multipath.c
>> index fe8f7f123fac..97d3c19b5684 100644
>> --- a/drivers/nvme/host/multipath.c
>> +++ b/drivers/nvme/host/multipath.c
>> @@ -272,8 +272,11 @@ inline struct nvme_ns *nvme_find_path(struct 
>> nvme_ns_head *head)
>>       struct nvme_ns *ns;
>>       ns = srcu_dereference(head->current_path[node], &head->srcu);
>> -    if (READ_ONCE(head->subsys->iopolicy) == NVME_IOPOLICY_RR && ns)
>> +    if (READ_ONCE(head->subsys->iopolicy) == NVME_IOPOLICY_RR && ns) {
>>           ns = nvme_round_robin_path(head, node, ns);
>> +        if (ns)
>> +            return ns;
>> +    }
>>       if (unlikely(!ns || !nvme_path_is_optimized(ns)))
>>           ns = __nvme_find_path(head, node);
> 
> Maybe instead of the early return put the following condition on else?

That depends on whether we want to have a fallback to __nvme_find_path() 
or not. With your suggestion we would lose that; I'd rather keep it.

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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