Implement media change notification for DA and CD removable media devices.

It includes three parts:
 1) Modifications to CAM to detect media media changes and report them to
disk(9) layer. For modern SATA (and potentially UAS) devices it utilizes
Asynchronous Notification mechanism to receive events from hardware.
Active polling with TEST UNIT READY commands with 3 seconds period is used
for incapable hardware. After that both CD and DA drivers work the same way,
detecting two conditions: "NOT READY: Medium not present" after medium was
detected previously, and "UNIT ATTENTION: Not ready to ready change, medium
may have changed". First one reported to disk(9) as media removal, second
as media insert/change. To reliably receive second event new
AC_UNIT_ATTENTION async added to make UAs broadcasted to all periphs by
generic error handling code in cam_periph_error().
 2) Modifications to GEOM core to handle media remove and change events.
Media removal handled by spoiling all consumers attached to the provider.
Media change event also schedules provider retaste after spoiling to probe
new media. New flag G_CF_ORPHAN was added to consumers to reflect that
consumer is in process of destruction. It allows retaste to create new
geom instance of the same class, while previous one is still dying.
 3) Modifications to some GEOM classes: DEV -- to report media change
events to devd; VFS -- to handle spoiling same as orphan to prevent
accessing replaced media. PART class already handles spoiling alike to
orphan.

Reviewed by:	silence on geom@ and scsi@
Tested by:	avg
Sponsored by:	iXsystems, Inc. / PC-BSD
MFC after:	2 months

1 files changed, 5 insertions, 1 deletions

diff --git a/sys/geom/geom.h b/sys/geom/geom.h
index 526fbdb..6a447ae 100644
--- a/sys/geom/geom.h
+++ b/sys/geom/geom.h
@@ -174,7 +174,9 @@ struct g_consumer {
 	struct g_provider	*provider;
 	LIST_ENTRY(g_consumer)	consumers;	/* XXX: better name */
 	int			acr, acw, ace;
-	int			spoiled;
+	int			flags;
+#define G_CF_SPOILED		0x1
+#define G_CF_ORPHAN		0x4
 	struct devstat		*stat;
 	u_int			nstart, nend;
 
@@ -247,6 +249,8 @@ int g_post_event(g_event_t *func, void *arg, int flag, ...);
 int g_waitfor_event(g_event_t *func, void *arg, int flag, ...);
 void g_cancel_event(void *ref);
 int g_attr_changed(struct g_provider *pp, const char *attr, int flag);
+int g_media_changed(struct g_provider *pp, int flag);
+int g_media_gone(struct g_provider *pp, int flag);
 void g_orphan_provider(struct g_provider *pp, int error);
 void g_waitidlelock(void);