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, 1 insertions, 0 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 6eed58e35e12..1ee9499bd343 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -5378,6 +5378,7 @@ struct ata_port *ata_port_alloc(struct ata_host *host)
         INIT_WORK(&ap->scsi_rescan_task, ata_scsi_dev_rescan);
         INIT_LIST_HEAD(&ap->eh_done_q);
         init_waitqueue_head(&ap->eh_wait_q);
+        init_completion(&ap->park_req_pending);
         init_timer_deferrable(&ap->fastdrain_timer);
         ap->fastdrain_timer.function = ata_eh_fastdrain_timerfn;
         ap->fastdrain_timer.data = (unsigned long)ap;