On Fri, 2011-12-02 at 15:31 -0500, Mike Snitzer wrote: > Thin provisioned LUNs from multiple array vendors have failed WRITE SAME > (16) w/ UNMAP bit set with ILLEGAL_REQUEST sense. With additional sense > 0x24 and 0x26 respectively. > > In both instances the target would always fail the CDB no matter how > many retries were performed (permanent target failure rather than > transient path failure). This resulted in mkfs.ext4's discard of a > multipath device looping indefinitely while failing paths. I don't quite understand this analysis. ILLEGAL_REQUEST currently always returns SUCCESS from scsi_check_sense(). That return is propagated up to scsi_decide_disposition() which causes I/O completion. We do have another gate for ILLEGAL_REQUEST in scsi_io_completion() which can retry, but only if it's downshifting the command from _10 to _6 ... so I don't get where you think the looping is coming from ... the net effect of your patch is to change the error passed on to the block layer in blk_end_request() from -EIO to -EREMOTEIO. So it sounds like if there is a retry problem it's above SCSI? James -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
