[SCSI] sd: Export effective protection mode in sysfs

Create a sysfs entry that reports the negotiated DIX/DIF protection mode
for a SCSI disk. This depends on the protection type the disk is
formatted with as well as the protection capabilities advertised by the
controller.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

1 files changed, 23 insertions, 0 deletions

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 57d1e3e1bd44..b9ab3a590e4b 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -259,6 +259,28 @@ sd_show_protection_type(struct device *dev, struct device_attribute *attr,
 }
 
 static ssize_t
+sd_show_protection_mode(struct device *dev, struct device_attribute *attr,
+                        char *buf)
+{
+        struct scsi_disk *sdkp = to_scsi_disk(dev);
+        struct scsi_device *sdp = sdkp->device;
+        unsigned int dif, dix;
+
+        dif = scsi_host_dif_capable(sdp->host, sdkp->protection_type);
+        dix = scsi_host_dix_capable(sdp->host, sdkp->protection_type);
+
+        if (!dix && scsi_host_dix_capable(sdp->host, SD_DIF_TYPE0_PROTECTION)) {
+                dif = 0;
+                dix = 1;
+        }
+
+        if (!dif && !dix)
+                return snprintf(buf, 20, "none\n");
+
+        return snprintf(buf, 20, "%s%u\n", dix ? "dix" : "dif", dif);
+}
+
+static ssize_t
 sd_show_app_tag_own(struct device *dev, struct device_attribute *attr,
                     char *buf)
 {
@@ -285,6 +307,7 @@ static struct device_attribute sd_disk_attrs[] = {
         __ATTR(manage_start_stop, S_IRUGO|S_IWUSR, sd_show_manage_start_stop,
                sd_store_manage_start_stop),
         __ATTR(protection_type, S_IRUGO, sd_show_protection_type, NULL),
+        __ATTR(protection_mode, S_IRUGO, sd_show_protection_mode, NULL),
         __ATTR(app_tag_own, S_IRUGO, sd_show_app_tag_own, NULL),
         __ATTR(thin_provisioning, S_IRUGO, sd_show_thin_provisioning, NULL),
         __ATTR_NULL,