sd: tweak discard heuristics to work around QEMU SCSI issue

[mirror_ubuntu-zesty-kernel.git] / drivers / scsi / sd.c

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index fedab3c21ddf18adcb291a99c49b7b4ac051aa85..399516925d802fea379938b9958778daa7ee37f2 100644 (file)
--- 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);