diff mbox

[PATCH/RFC,V2,09/16] scsi: sd: Avoid sending medium write commands if device is write protected

Message ID 1408023067-26103-10-git-send-email-draviv@codeaurora.org (mailing list archive)
State Deferred
Headers show

Commit Message

Dolev Raviv Aug. 14, 2014, 1:31 p.m. UTC 
From: Sujit Reddy Thumma <sthumma@codeaurora.org>

The SYNCHRONIZE_CACHE command is a medium write command and hence can
fail when the device is write protected. Avoid sending such commands by
making sure that write-cache-enable is disabled even though the device
claim to support it.

Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>
Signed-off-by: Dolev Raviv <draviv@codeaurora.org>
diff mbox

Patch

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 3663e38..67282bf 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -185,7 +185,7 @@  cache_type_store(struct device *dev, struct device_attribute *attr,
 	if (ct < 0)
 		return -EINVAL;
 	rcd = ct & 0x01 ? 1 : 0;
-	wce = ct & 0x02 ? 1 : 0;
+	wce = (ct & 0x02) && !sdkp->write_prot ? 1 : 0;
 
 	if (sdkp->cache_override) {
 		sdkp->WCE = wce;
@@ -2493,6 +2493,10 @@  sd_read_cache_type(struct scsi_disk *sdkp, unsigned char *buffer)
 			sdkp->DPOFUA = 0;
 		}
 
+		/* No cache flush allowed for write protected devices */
+		if (sdkp->WCE && sdkp->write_prot)
+			sdkp->WCE = 0;
+
 		if (sdkp->first_scan || old_wce != sdkp->WCE ||
 		    old_rcd != sdkp->RCD || old_dpofua != sdkp->DPOFUA)
 			sd_printk(KERN_NOTICE, sdkp,