libata: Implement disk shock protection support

On user request (through sysfs), the IDLE IMMEDIATE command with UNLOAD
FEATURE as specified in ATA-7 is issued to the device and processing of
the request queue is stopped thereafter until the specified timeout
expires or user space asks to resume normal operation. This is supposed
to prevent the heads of a hard drive from accidentally crashing onto the
platter when a heavy shock is anticipated (like a falling laptop
expected to hit the floor). In fact, the whole port stops processing
commands until the timeout has expired in order to avoid any resets due
to failed commands on another device.

Signed-off-by: Elias Oltmanns <eo@nebensachen.de>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 108 insertions, 0 deletions

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index b9d3ba423cb2..fccd5e496c62 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -183,6 +183,105 @@ DEVICE_ATTR(link_power_management_policy, S_IRUGO | S_IWUSR,
                 ata_scsi_lpm_show, ata_scsi_lpm_put);
 EXPORT_SYMBOL_GPL(dev_attr_link_power_management_policy);
 
+static ssize_t ata_scsi_park_show(struct device *device,
+                                  struct device_attribute *attr, char *buf)
+{
+        struct scsi_device *sdev = to_scsi_device(device);
+        struct ata_port *ap;
+        struct ata_link *link;
+        struct ata_device *dev;
+        unsigned long flags;
+        unsigned int uninitialized_var(msecs);
+        int rc = 0;
+
+        ap = ata_shost_to_port(sdev->host);
+
+        spin_lock_irqsave(ap->lock, flags);
+        dev = ata_scsi_find_dev(ap, sdev);
+        if (!dev) {
+                rc = -ENODEV;
+                goto unlock;
+        }
+        if (dev->flags & ATA_DFLAG_NO_UNLOAD) {
+                rc = -EOPNOTSUPP;
+                goto unlock;
+        }
+
+        link = dev->link;
+        if (ap->pflags & ATA_PFLAG_EH_IN_PROGRESS &&
+            link->eh_context.unloaded_mask & (1 << dev->devno) &&
+            time_after(dev->unpark_deadline, jiffies))
+                msecs = jiffies_to_msecs(dev->unpark_deadline - jiffies);
+        else
+                msecs = 0;
+
+unlock:
+        spin_unlock_irq(ap->lock);
+
+        return rc ? rc : snprintf(buf, 20, "%u\n", msecs);
+}
+
+static ssize_t ata_scsi_park_store(struct device *device,
+                                   struct device_attribute *attr,
+                                   const char *buf, size_t len)
+{
+        struct scsi_device *sdev = to_scsi_device(device);
+        struct ata_port *ap;
+        struct ata_device *dev;
+        long int input;
+        unsigned long flags;
+        int rc;
+
+        rc = strict_strtol(buf, 10, &input);
+        if (rc || input < -2)
+                return -EINVAL;
+        if (input > ATA_TMOUT_MAX_PARK) {
+                rc = -EOVERFLOW;
+                input = ATA_TMOUT_MAX_PARK;
+        }
+
+        ap = ata_shost_to_port(sdev->host);
+
+        spin_lock_irqsave(ap->lock, flags);
+        dev = ata_scsi_find_dev(ap, sdev);
+        if (unlikely(!dev)) {
+                rc = -ENODEV;
+                goto unlock;
+        }
+        if (dev->class != ATA_DEV_ATA) {
+                rc = -EOPNOTSUPP;
+                goto unlock;
+        }
+
+        if (input >= 0) {
+                if (dev->flags & ATA_DFLAG_NO_UNLOAD) {
+                        rc = -EOPNOTSUPP;
+                        goto unlock;
+                }
+
+                dev->unpark_deadline = ata_deadline(jiffies, input);
+                dev->link->eh_info.dev_action[dev->devno] |= ATA_EH_PARK;
+                ata_port_schedule_eh(ap);
+                complete(&ap->park_req_pending);
+        } else {
+                switch (input) {
+                case -1:
+                        dev->flags &= ~ATA_DFLAG_NO_UNLOAD;
+                        break;
+                case -2:
+                        dev->flags |= ATA_DFLAG_NO_UNLOAD;
+                        break;
+                }
+        }
+unlock:
+        spin_unlock_irqrestore(ap->lock, flags);
+
+        return rc ? rc : len;
+}
+DEVICE_ATTR(unload_heads, S_IRUGO | S_IWUSR,
+            ata_scsi_park_show, ata_scsi_park_store);
+EXPORT_SYMBOL_GPL(dev_attr_unload_heads);
+
 static void ata_scsi_set_sense(struct scsi_cmnd *cmd, u8 sk, u8 asc, u8 ascq)
 {
         cmd->result = (DRIVER_SENSE << 24) | SAM_STAT_CHECK_CONDITION;
@@ -269,6 +368,12 @@ DEVICE_ATTR(sw_activity, S_IWUGO | S_IRUGO, ata_scsi_activity_show,
                         ata_scsi_activity_store);
 EXPORT_SYMBOL_GPL(dev_attr_sw_activity);
 
+struct device_attribute *ata_common_sdev_attrs[] = {
+        &dev_attr_unload_heads,
+        NULL
+};
+EXPORT_SYMBOL_GPL(ata_common_sdev_attrs);
+
 static void ata_scsi_invalid_field(struct scsi_cmnd *cmd,
                                    void (*done)(struct scsi_cmnd *))
 {
@@ -954,6 +1059,9 @@ static int atapi_drain_needed(struct request *rq)
 static int ata_scsi_dev_config(struct scsi_device *sdev,
                                struct ata_device *dev)
 {
+        if (!ata_id_has_unload(dev->id))
+                dev->flags |= ATA_DFLAG_NO_UNLOAD;
+
         /* configure max sectors */
         blk_queue_max_sectors(sdev->request_queue, dev->max_sectors);