[SCSI] libata, libsas: introduce sched_eh and end_eh port ops

When managing shost->host_eh_scheduled libata assumes that there is a
1:1 shost-to-ata_port relationship.  libsas creates a 1:N relationship
so it needs to manage host_eh_scheduled cumulatively at the host level.
The sched_eh and end_eh port port ops allow libsas to track when domain
devices enter/leave the "eh-pending" state under ha->lock (previously
named ha->state_lock, but it is no longer just a lock for ha->state
changes).

Since host_eh_scheduled indicates eh without backing commands pinning
the device it can be deallocated at any time.  Move the taking of the
domain_device reference under the port_lock to guarantee that the
ata_port stays around for the duration of eh.

Reviewed-by: Jacek Danecki <jacek.danecki@intel.com>
Acked-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
index 10ce74f589c5..814d8cb592ad 100644
--- a/include/scsi/libsas.h
+++ b/include/scsi/libsas.h
@@ -179,6 +179,7 @@ struct sata_device {
 enum {
         SAS_DEV_GONE,
         SAS_DEV_DESTROY,
+        SAS_DEV_EH_PENDING,
 };
 
 struct domain_device {
@@ -386,7 +387,8 @@ struct sas_ha_struct {
         struct list_head  defer_q; /* work queued while draining */
         struct mutex      drain_mutex;
         unsigned long     state;
-        spinlock_t        state_lock;
+        spinlock_t        lock;
+        int               eh_active;
 
         struct mutex disco_mutex;