On 05/30/2018 09:45 AM, Christoph Hellwig wrote:
> Just keep a per-controller buffer of changed namespaces and copy it out
> in the get log page implementation.
> 
> Signed-off-by: Christoph Hellwig <[email protected]>
> ---
[...]
> +static void nvmet_add_to_changed_ns_log(struct nvmet_ctrl *ctrl, __le32 nsid)
> +{
> +     mutex_lock(&ctrl->lock);
> +     if (ctrl->nr_changed_ns < NVME_MAX_CHANGED_NAMESPACES) {

Minor nitpick here: if ctrlr->nr_changed_ns is exactly
NVME_MAX_CHANGED_NAMESPACES and the new nsid is already in the list,
this will skip down to the 0xffffffff case below, even though it could
have just left the list as-is.

I don't know if this is a problem in practice; reporting 0xffffffff is
probably always safe, since the host will presumably treat that as
"rescan everything".

> +             u32 i;
> +
> +             for (i = 0; i < ctrl->nr_changed_ns; i++)
> +                     if (ctrl->changed_ns_list[i] == nsid)
> +                             goto out_unlock;
> +             ctrl->changed_ns_list[ctrl->nr_changed_ns++] = nsid;
> +     } else if (ctrl->nr_changed_ns == NVME_MAX_CHANGED_NAMESPACES) {
> +             ctrl->changed_ns_list[0] = cpu_to_le32(0xffffffff);
> +             ctrl->nr_changed_ns = U32_MAX;
> +     }
> +out_unlock:
> +     mutex_unlock(&ctrl->lock);
> +}

Thanks,
-- Daniel

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