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authorSujit Reddy Thumma <sthumma@codeaurora.org>2014-08-11 15:40:37 +0300
committerChristoph Hellwig <hch@lst.de>2014-09-15 16:01:57 -0700
commit2eefd57b97609949ae40952da2dea338e7d9a125 (patch)
tree9010e184d6af69458b34cf6239ba2e4ba6ef8c9c /drivers/scsi/sd.c
parent74cf298fedfcb732335cae5d157e95295e87cf2a (diff)
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>
Diffstat (limited to 'drivers/scsi/sd.c')
-rw-r--r--drivers/scsi/sd.c6
1 files changed, 5 insertions, 1 deletions
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,