[dm-devel] [PATCH v4 1/3] scsi: scsi_ioctl: export __scsi_result_to_blk_status()

[Paolo Bonzini]

On 01/07/21 08:19, Christoph Hellwig wrote:
> http://git.infradead.org/users/hch/block.git/shortlog/refs/heads/scsi-ioctl
> 
> But more importantly, dm has no business interpreting the errors.  Just
> like how SG_IO processing generally does not look at the error and
> just returns it to userspace and leaves error handling to the caller
> so should be the decision to resubmit it in a multi-path setup.

The problem is that userspace does not have a way to direct the command 
to a different path in the resubmission.  It may not even have 
permission to issue DM_TABLE_STATUS, or to access the /dev nodes for the 
underlying paths, so without Martin's patches SG_IO on dm-mpath is 
basically unreliable by design.

Paolo