[PATCH] nvme: add namespace paths links

[Sagi Grimberg]

On 9/12/23 17:04, Hannes Reinecke wrote:
> On 9/12/23 14:55, Sagi Grimberg wrote:
>>
>>>>> It is really annoying to always have to loop through the entire
>>>>> /sys/block directory just to find the namespace path links for
>>>>> a single namespace in libnvme/nvme-cli.
>>>>> So provide links to the namespace paths for efficient lookup.
>>>>>
>>>>> Signed-off-by: Hannes Reinecke <hare at suse.de>
>>>>> ---
>>>>>   drivers/nvme/host/core.c      |  3 +++
>>>>>   drivers/nvme/host/multipath.c | 10 ++++++++++
>>>>>   2 files changed, 13 insertions(+)
>>>>>
>>>>> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
>>>>> index 37b6fa746662..88933838e067 100644
>>>>> --- a/drivers/nvme/host/core.c
>>>>> +++ b/drivers/nvme/host/core.c
>>>>> @@ -3681,6 +3681,9 @@ static void nvme_ns_remove(struct nvme_ns *ns)
>>>>>       if (!nvme_ns_head_multipath(ns->head))
>>>>>           nvme_cdev_del(&ns->cdev, &ns->cdev_device);
>>>>> +    else
>>>>> +        sysfs_remove_link(&disk_to_dev(ns->head->disk)->kobj,
>>>>> +                  ns->disk->disk_name);
>>>>>       del_gendisk(ns->disk);
>>>>>       down_write(&ns->ctrl->namespaces_rwsem);
>>>>> diff --git a/drivers/nvme/host/multipath.c 
>>>>> b/drivers/nvme/host/multipath.c
>>>>> index 0a88d7bdc5e3..9dd0be645dad 100644
>>>>> --- a/drivers/nvme/host/multipath.c
>>>>> +++ b/drivers/nvme/host/multipath.c
>>>>> @@ -875,6 +875,16 @@ void nvme_mpath_add_disk(struct nvme_ns *ns, 
>>>>> __le32 anagrpid)
>>>>>       if (blk_queue_is_zoned(ns->queue) && ns->head->disk)
>>>>>           ns->head->disk->nr_zones = ns->disk->nr_zones;
>>>>>   #endif
>>>>> +    if (ns->head->disk) {
>>>>
>>>> Why are the two conditions not identical?
>>>>
>>> Which two?
>>
>> ns->head->disk and nvme_ns_head_multipath()
>>
> How can we have one without the other? I thought that both are mutually 
> dependent .. but yeah, we should be using 'nvme_ns_head_multipath()' here.
> 
>>>
>>>>> +        int ret;
>>>>> +
>>>>> +        ret = sysfs_create_link(&disk_to_dev(ns->head->disk)->kobj,
>>>>> +                    &disk_to_dev(ns->disk)->kobj,
>>>>> +                    ns->disk->disk_name);
>>>>> +        if (ret)
>>>>> +            dev_warn(ns->ctrl->device,
>>>>> +                 "failed to create namespace path link\n");
>>>>> +    }
>>>>>   }
>>>>>   void nvme_mpath_shutdown_disk(struct nvme_ns_head *head)
>>>>
>>>> What will these links be used for?
>>>
>>> Mapping for nvme-cli, as explained in the description.
>>> Clearly it doesn't do it _now_, but once the patch is in we can
>>> simplify nvme-cli to take advantage of it.
>>
>> you mean for nvme list -v ?
>>
>> Don't really mind having it, but would want to hear from others as
>> well.
> 
> Ok.

Hey Hannes,
Has this gone anywhere?