3.18-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jeremy Cline <jeremy@xxxxxxxxxx>
[ Upstream commit 20bd1d026aacc5399464f8328f305985c493cde3 ]
If the read-only flag is true on a SCSI disk, re-reading the partition
table sets the flag back to false.
To observe this bug, you can run:
1. blockdev --setro /dev/sda
2. blockdev --rereadpt /dev/sda
3. blockdev --getro /dev/sda
This commit reads the disk's old state and combines it with the device
disk-reported state rather than unconditionally marking it as RW.
Reported-by: Li Ning <lining916740672@xxxxxxxxxx>
Signed-off-by: Jeremy Cline <jeremy@xxxxxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/scsi/sd.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2318,6 +2318,7 @@ sd_read_write_protect_flag(struct scsi_d
int res;
struct scsi_device *sdp = sdkp->device;
struct scsi_mode_data data;
+ int disk_ro = get_disk_ro(sdkp->disk);
int old_wp = sdkp->write_prot;
set_disk_ro(sdkp->disk, 0);
@@ -2358,7 +2359,7 @@ sd_read_write_protect_flag(struct scsi_d
"Test WP failed, assume Write Enabled\n");
} else {
sdkp->write_prot = ((data.device_specific & 0x80) != 0);
- set_disk_ro(sdkp->disk, sdkp->write_prot);
+ set_disk_ro(sdkp->disk, sdkp->write_prot || disk_ro);
if (sdkp->first_scan || old_wp != sdkp->write_prot) {
sd_printk(KERN_NOTICE, sdkp, "Write Protect is %s\n",
sdkp->write_prot ? "on" : "off");
