Commit 2eefd57b authored Aug 11, 2014 by Sujit Reddy Thumma Committed by Christoph Hellwig Sep 15, 2014

sd: Avoid sending medium write commands if device is write protected



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>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Venkatesh Srinivas <venkateshs@google.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

parent 74cf298f

drivers/scsi/sd.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -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;
		@@ -2490,6 +2490,10 @@ 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,