From 2eefd57b97609949ae40952da2dea338e7d9a125 Mon Sep 17 00:00:00 2001 From: Sujit Reddy Thumma Date: Mon, 11 Aug 2014 15:40:37 +0300 Subject: [PATCH] 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 Signed-off-by: Dolev Raviv Reviewed-by: Martin K. Petersen Reviewed-by: Venkatesh Srinivas Signed-off-by: Christoph Hellwig --- drivers/scsi/sd.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index 2c2041ca4b70..aa43496b7b93 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; @@ -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,