Re: [PATCH v2 09/20] nvme: Add helper to execute Reservation Report

Mike Christie
2022-08-09T16:21:39Z

On 8/9/22 9:51 AM, Keith Busch wrote:
> On Tue, Aug 09, 2022 at 10:56:55AM +0000, Chaitanya Kulkarni wrote:
>> On 8/8/22 17:04, Mike Christie wrote:
>>> +
>>> + c.common.opcode = nvme_cmd_resv_report;
>>> + c.common.cdw10 = cpu_to_le32(nvme_bytes_to_numd(data_len));
>>> + c.common.cdw11 = 1;
>>> + *eds = true;
>>> +
>>> +retry:
>>> + if (IS_ENABLED(CONFIG_NVME_MULTIPATH) &&
>>> + bdev->bd_disk->fops == &nvme_ns_head_ops)
>>> + ret = nvme_send_ns_head_pr_command(bdev, &c, data, data_len);
>>> + else
>>> + ret = nvme_send_ns_pr_command(bdev->bd_disk->private_data, &c,
>>> + data, data_len);
>>> + if (ret == NVME_SC_HOST_ID_INCONSIST && c.common.cdw11) {
>>> + c.common.cdw11 = 0;
>>> + *eds = false;
>>> + goto retry;
>>
>> Unconditional retries without any limit can create problems,
>> perhaps consider adding some soft limits.
>
> It's already conditioned on cdw11, which is cleared to 0 on the 2nd try. Not
> that that's particularly clear. I'd suggest naming an enum value for it so the
> code tells us what the signficance of cdw11 is in this context (it's the
> Extended Data Structure control flag).

Will do that.

Chaitanya for your comment, with a bad device we could hit an issue where we
we cleared the Extended Data Structure control flag and it also returned
NVME_SC_HOST_ID_INCONSIST and we'd be in an infinite loop, so I'll handle that.