From: Tom Yan <tom.t...@gmail.com>
Example:
[root@localhost ~]# sg_opcodes /dev/sdb > /dev/null
Report supported operation codes: Illegal request, invalid opcode
[root@localhost ~]# sg_vpd -p bl /dev/sdb | grep 'write same'
Maximum write same length: 0x0 blocks
[root@localhost ~]# cat /sys/block/sdb/queue/write_same_max_bytes
33553920
Signed-off-by: Tom Yan <tom.t...@gmail.com>
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index d749da7..1179ec1 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -807,6 +807,8 @@ static void sd_config_write_same(struct scsi_disk *sdkp)
if (sdkp->max_ws_blocks > SD_MAX_WS10_BLOCKS)
sdkp->max_ws_blocks = min_not_zero(sdkp->max_ws_blocks,
(u32)SD_MAX_WS16_BLOCKS);
+ else if (sdkp->max_ws_blocks == 0 && sdkp->device->no_report_opcodes)
+ sdkp->device->no_write_same = 1;
else if (sdkp->ws16 || sdkp->ws10 || sdkp->device->no_report_opcodes)
sdkp->max_ws_blocks = min_not_zero(sdkp->max_ws_blocks,
(u32)SD_MAX_WS10_BLOCKS);
--
2.7.1
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