On Mon, Jun 3, 2013 at 8:47 AM, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
> On 06/02/2013 11:14 PM, Dan Williams wrote:
>>
>> If I'm reading things correctly that may still result in failure since
>> md will still pass the REQ_WRITE_SAME bios down to the the devices and
>> will receive BLK_PREP_KILL for its trouble. md only notices that
>> write same is disabled on underlying devices at assembly time.
>>
>
> I have to admit to not seeing where md (as opposed to dm) even looks for
> if the underlying devices have write same enabled. It seems extremely
> likely that it is write same that is causing the headaches, though.
>
raid10 calls disk_stack_limits() after blk_queue_max_write_same_sectors().
...and here is where scsi considers failures as non-fatal in
sd_done(). I assume the REQ_QUIET is why there are no other kernel
messages.
case ILLEGAL_REQUEST:
if (sshdr.asc == 0x10) /* DIX: Host detected corruption */
good_bytes = sd_completed_bytes(SCpnt);
/* INVALID COMMAND OPCODE or INVALID FIELD IN CDB */
if (sshdr.asc == 0x20 || sshdr.asc == 0x24) {
switch (op) {
case UNMAP:
sd_config_discard(sdkp, SD_LBP_DISABLE);
break;
case WRITE_SAME_16:
case WRITE_SAME:
if (unmap)
sd_config_discard(sdkp, SD_LBP_DISABLE);
else {
sdkp->device->no_write_same = 1;
sd_config_write_same(sdkp);
good_bytes = 0;
req->__data_len = blk_rq_bytes(req);
req->cmd_flags |= REQ_QUIET;
}
}
}
break;
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