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SubjectRe: [RFC] IB/srp: export reset-host via sysfs
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On 04.10.2016 16:24, Bart Van Assche wrote:
> On 10/04/16 07:00, Gioh Kim wrote:
>> Standard SCSI device has host_reset sysfs interface.
>> This patch exports the host_reset interface for upper layer.
>>
>> Signed-off-by: Gioh Kim <gi-oh.kim@profitbricks.com>
>> ---
>> drivers/infiniband/ulp/srp/ib_srp.c | 10 ++++++++++
>> 1 file changed, 10 insertions(+)
>>
>> diff --git a/drivers/infiniband/ulp/srp/ib_srp.c
>> b/drivers/infiniband/ulp/srp/ib_srp.c
>> index 3322ed7..92e6c3f 100644
>> --- a/drivers/infiniband/ulp/srp/ib_srp.c
>> +++ b/drivers/infiniband/ulp/srp/ib_srp.c
>> @@ -2628,6 +2628,15 @@ static int srp_reset_device(struct scsi_cmnd
>> *scmnd)
>> return SUCCESS;
>> }
>>
>> +static int srp_scsi_host_reset(struct Scsi_Host *shost, int reset_type)
>> +{
>> + struct srp_target_port *target = host_to_target(shost);
>> +
>> + shost_printk(KERN_EMERG, target->scsi_host, PFX "SRP reset_host
>> called\n");
>> +
>> + return srp_reconnect_rport(target->rport);
>> +}
>> +
>> static int srp_reset_host(struct scsi_cmnd *scmnd)
>> {
>> struct srp_target_port *target =
>> host_to_target(scmnd->device->host);
>> @@ -2858,6 +2867,7 @@ static struct scsi_host_template srp_template = {
>> .use_clustering = ENABLE_CLUSTERING,
>> .shost_attrs = srp_host_attrs,
>> .track_queue_depth = 1,
>> + .host_reset = srp_scsi_host_reset,
>> };
>
> Hello Gioh,
>
> A patch description should not only explain what is changed but also
> why a change is considered useful. Why do you think it would be useful
> to allow users to trigger a call of srp_reconnect_rport() through
> sysfs instead of using the functionality that is already available
> through sysfs, namely removing a SCSI host and reconnecting?
Hello Bart,

It's my mistake to miss 0000-cover-letter.patch file including description.

I'm testing SCSI devices which are exported by the remote servers via IB
network. I know that SCSI error handling mechanism calls reset-host when
something wrong happens. But the SCSI error handling tries sending ABORT
commands and other actions before resetting host. I found that those
ABORT commands could generate more stress on the remove server. So I
need to reset SCSI host (which mean reconnecting) when the remote server
starts to become slow or have some problem to handle IO.

And I think I can use some utilities for SCSI device, such like sg3
utils, to handle srp connection.

Thank you for your reply.

Best regards,
Gioh Kim

>
> Bart.
>

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