On Sun, Jul 13, 2014 at 08:58:34AM -0400, Martin K. Petersen wrote: > >>>>> "KY" == KY Srinivasan <kys@xxxxxxxxxxxxx> writes: > > KY> Windows hosts do support UNMAP and set the field in the > KY> EVPD. However, since the host advertises SPC-2 compliance, Linux > KY> does not even query the VPD page. > > >> If we want to enable UNMAP in this case I'd prefer a blacklist entry > >> than trying UNMAP despite the device not advertising it. > > I agree with that. We could do something like the patch below. > > However, I do think it's a good idea that you guys are looking into > reporting SPC-3. KY mentioned that they have a prototype for that now. Btw, I looked over sd.c a bit more, and I think I understand why they get the WRITE SAME commands now: read_capacity_16 calls sd_config_discard(sdkp, SD_LBP_WS16) if the LPBME bit is set. At least older SBC drafts left it wide open if a target supports WRITE SAME with UNMAP or UNMAP in this case. So I think we'd still want a patch to use UNMAP instead of WRITE SAME for this case, which should also fix hyperv. Below is the quick hack version of that that just checks the host no_write_same flag, as the one on the device isn't set yet - I guess we need to refactor some of that logic. diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index 87566b5..4480fdf 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -2035,7 +2035,10 @@ static int read_capacity_16(struct scsi_disk *sdkp, struct scsi_device *sdp, if (buffer[14] & 0x40) /* LBPRZ */ sdkp->lbprz = 1; - sd_config_discard(sdkp, SD_LBP_WS16); + if (sdp->host->no_write_same) + sd_config_discard(sdkp, SD_LBP_UNMAP); + else + sd_config_discard(sdkp, SD_LBP_WS16); } sdkp->capacity = lba + 1; -- 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
