[PATCH v6 1/3] scsi: sd: Add manage_restart device attribute to scsi_disk

[Markus Probst <markus.probst@posteo.de>]

In addition to the already existing manage_shutdown,
manage_system_start_stop and manage_runtime_start_stop device
scsi_disk attributes, add manage_restart, which allows the high-level
device driver (sd) to manage the device power state for SYSTEM_RESTART if
set to 1.

This attribute is necessary for the following commit "ata: stop disk on
restart if ACPI power resources are found" to avoid a potential disk power
failure in the case the SATA power connector does not retain the power
state after a restart.

Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Markus Probst <markus.probst@posteo.de>
---
 drivers/scsi/sd.c          | 34 +++++++++++++++++++++++++++++++++-
 include/scsi/scsi_device.h |  6 ++++++
 2 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 0252d3f6bed1..f2c0744b4480 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -318,6 +318,35 @@ static ssize_t manage_shutdown_store(struct device *dev,
 }
 static DEVICE_ATTR_RW(manage_shutdown);
 
+static ssize_t manage_restart_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	struct scsi_disk *sdkp = to_scsi_disk(dev);
+	struct scsi_device *sdp = sdkp->device;
+
+	return sysfs_emit(buf, "%u\n", sdp->manage_restart);
+}
+
+static ssize_t manage_restart_store(struct device *dev,
+				    struct device_attribute *attr,
+				    const char *buf, size_t count)
+{
+	struct scsi_disk *sdkp = to_scsi_disk(dev);
+	struct scsi_device *sdp = sdkp->device;
+	bool v;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EACCES;
+
+	if (kstrtobool(buf, &v))
+		return -EINVAL;
+
+	sdp->manage_restart = v;
+
+	return count;
+}
+static DEVICE_ATTR_RW(manage_restart);
+
 static ssize_t
 allow_restart_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
@@ -654,6 +683,7 @@ static struct attribute *sd_disk_attrs[] = {
 	&dev_attr_manage_system_start_stop.attr,
 	&dev_attr_manage_runtime_start_stop.attr,
 	&dev_attr_manage_shutdown.attr,
+	&dev_attr_manage_restart.attr,
 	&dev_attr_protection_type.attr,
 	&dev_attr_protection_mode.attr,
 	&dev_attr_app_tag_own.attr,
@@ -4177,7 +4207,9 @@ static void sd_shutdown(struct device *dev)
 	    (system_state == SYSTEM_POWER_OFF &&
 	     sdkp->device->manage_shutdown) ||
 	    (system_state == SYSTEM_RUNNING &&
-	     sdkp->device->manage_runtime_start_stop)) {
+	     sdkp->device->manage_runtime_start_stop) ||
+	    (system_state == SYSTEM_RESTART &&
+	     sdkp->device->manage_restart)) {
 		sd_printk(KERN_NOTICE, sdkp, "Stopping disk\n");
 		sd_start_stop_device(sdkp, 0);
 	}
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index 993008cdea65..fd484d48df77 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -178,6 +178,12 @@ struct scsi_device {
 	 */
 	unsigned manage_shutdown:1;
 
+	/*
+	 * If true, let the high-level device driver (sd) manage the device
+	 * power state for system restart (reboot) operations.
+	 */
+	unsigned manage_restart:1;
+
 	/*
 	 * If set and if the device is runtime suspended, ask the high-level
 	 * device driver (sd) to force a runtime resume of the device.
-- 
2.51.0