scsi: sd: Introduce manage_shutdown device flag

Commit aa3998dbeb3a ("ata: libata-scsi: Disable scsi device
manage_system_start_stop") change setting the manage_system_start_stop
flag to false for libata managed disks to enable libata internal
management of disk suspend/resume. However, a side effect of this change
is that on system shutdown, disks are no longer being stopped (set to
standby mode with the heads unloaded). While this is not a critical
issue, this unclean shutdown is not recommended and shows up with
increased smart counters (e.g. the unexpected power loss counter
"Unexpect_Power_Loss_Ct").

Instead of defining a shutdown driver method for all ATA adapter
drivers (not all of them define that operation), this patch resolves
this issue by further refining the sd driver start/stop control of disks
using the new flag manage_shutdown. If this new flag is set to true by
a low level driver, the function sd_shutdown() will issue a
START STOP UNIT command with the start argument set to 0 when a disk
needs to be powered off (suspended) on system power off, that is, when
system_state is equal to SYSTEM_POWER_OFF.

Similarly to the other manage_xxx flags, the new manage_shutdown flag is
exposed through sysfs as a read-write device attribute.

To avoid any confusion between manage_shutdown and
manage_system_start_stop, the comments describing these flags in
include/scsi/scsi.h are also improved.

Fixes: aa3998dbeb3a ("ata: libata-scsi: Disable scsi device manage_system_start_stop")
Cc: stable@vger.kernel.org
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218038
Link: https://lore.kernel.org/all/cd397c88-bf53-4768-9ab8-9d107df9e613@gmail.com/
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Niklas Cassel <niklas.cassel@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 36 insertions, 3 deletions

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 83b6a3f3863b..6effa13039f3 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -209,7 +209,8 @@ manage_start_stop_show(struct device *dev,
 
 	return sysfs_emit(buf, "%u\n",
 			  sdp->manage_system_start_stop &&
-			  sdp->manage_runtime_start_stop);
+			  sdp->manage_runtime_start_stop &&
+			  sdp->manage_shutdown);
 }
 static DEVICE_ATTR_RO(manage_start_stop);
 
@@ -275,6 +276,35 @@ manage_runtime_start_stop_store(struct device *dev,
 }
 static DEVICE_ATTR_RW(manage_runtime_start_stop);
 
+static ssize_t manage_shutdown_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_shutdown);
+}
+
+static ssize_t manage_shutdown_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_shutdown = v;
+
+	return count;
+}
+static DEVICE_ATTR_RW(manage_shutdown);
+
 static ssize_t
 allow_restart_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
@@ -607,6 +637,7 @@ static struct attribute *sd_disk_attrs[] = {
 	&dev_attr_manage_start_stop.attr,
 	&dev_attr_manage_system_start_stop.attr,
 	&dev_attr_manage_runtime_start_stop.attr,
+	&dev_attr_manage_shutdown.attr,
 	&dev_attr_protection_type.attr,
 	&dev_attr_protection_mode.attr,
 	&dev_attr_app_tag_own.attr,
@@ -3819,8 +3850,10 @@ static void sd_shutdown(struct device *dev)
 		sd_sync_cache(sdkp, NULL);
 	}
 
-	if (system_state != SYSTEM_RESTART &&
-	    sdkp->device->manage_system_start_stop) {
+	if ((system_state != SYSTEM_RESTART &&
+	     sdkp->device->manage_system_start_stop) ||
+	    (system_state == SYSTEM_POWER_OFF &&
+	     sdkp->device->manage_shutdown)) {
 		sd_printk(KERN_NOTICE, sdkp, "Stopping disk\n");
 		sd_start_stop_device(sdkp, 0);
 	}