Re: dm: dm_blk_ioctl(): implement failover for SG_IO on dm-multipath

[Paolo Bonzini <pbonzini@redhat.com>]

On 29/04/21 10:33, Martin Wilck wrote:
> On Wed, 2021-04-28 at 15:54 -0400, Mike Snitzer wrote:
>>
>> @@ -626,32 +626,16 @@ static int dm_sg_io_ioctl(struct block_device
>> *bdev, fmode_t mode,
>>                  }
>>   
>>                  if (rhdr.info & SG_INFO_CHECK) {
>> -                       /*
>> -                        * See if this is a target or path error.
>> -                        * Compare blk_path_error(),
>> scsi_result_to_blk_status(),
>> -                        * blk_errors[].
>> -                        */
>> -                       switch (rhdr.host_status) {
>> -                       case DID_OK:
>> -                               if (scsi_status_is_good(rhdr.status))
>> -                                       rc = 0;
>> -                               break;
>> -                       case DID_TARGET_FAILURE:
>> -                               rc = -EREMOTEIO;
>> -                               goto out;
>> -                       case DID_NEXUS_FAILURE:
>> -                               rc = -EBADE;
>> -                               goto out;
>> -                       case DID_ALLOC_FAILURE:
>> -                               rc = -ENOSPC;
>> -                               goto out;
>> -                       case DID_MEDIUM_ERROR:
>> -                               rc = -ENODATA;
>> -                               goto out;
>> -                       default:
>> -                               /* Everything else is a path error */
>> +                       blk_status_t sts =
>> scsi_result_to_blk_status(rhdr.host_status, NULL);
> 
> This change makes dm_mod depend on scsi_mod.
> Would you seriously prefer that over a re-implementation of the logic?

You could just make it an inline function too.

Paolo