>>>>> "Ming" == Ming Lei <ming.lei@xxxxxxxxxxxxx> writes:
>> What about in READ CAPACITY(16)?
Ming> It isn't set too.
Please try the following patch:
[SCSI] sd: Tweak discard heuristics to work around QEMU SCSI issue
7985090aa020 changed the discard heuristics to give preference to the
WRITE SAME commands that (unlike UNMAP) guarantee deterministic results.
Ming Lei discovered that QEMU SCSI's WRITE SAME implementation
internally relied on limits that were only communicated for the UNMAP
case. And therefore discard commands backed by WRITE SAME would fail.
Tweak the heuristics so we still pick UNMAP in the LBPRZ=0 case and only
prefer the WRITE SAME variants if the device has the LBPRZ flag set.
Reported-by: Ming Lei <ming.lei@xxxxxxxxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 95bfb7bfbb9d..76c5d1388417 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2623,8 +2623,9 @@ static void sd_read_block_limits(struct scsi_disk *sdkp)
sd_config_discard(sdkp, SD_LBP_WS16);
} else { /* LBP VPD page tells us what to use */
-
- if (sdkp->lbpws)
+ if (sdkp->lbpu && sdkp->max_unmap_blocks && !sdkp->lbprz)
+ sd_config_discard(sdkp, SD_LBP_UNMAP);
+ else if (sdkp->lbpws)
sd_config_discard(sdkp, SD_LBP_WS16);
else if (sdkp->lbpws10)
sd_config_discard(sdkp, SD_LBP_WS10);
--
Martin K. Petersen Oracle Linux Engineering
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