Move snapshot metadata loading to happen when table is created instead
of when device is resumed.  Origin writes don't trigger exceptions until
snapshot table becomes active (when resume() is called on snapshot).

NB This patch may break some existing LVM2 and EVMS operations.
--- diff/drivers/md/dm-snap.c	2005-07-06 17:18:35.000000000 +0100
+++ source/drivers/md/dm-snap.c	2005-07-06 17:18:42.000000000 +0100
@@ -373,16 +373,11 @@
 
 static void read_snapshot_metadata(struct dm_snapshot *s)
 {
-	if (s->have_metadata)
-		return;
-
 	if (s->store.read_metadata(&s->store)) {
 		down_write(&s->lock);
 		s->valid = 0;
 		up_write(&s->lock);
 	}
-
-	s->have_metadata = 1;
 }
 
 /*
@@ -471,7 +466,7 @@
 	s->chunk_shift = ffs(chunk_size) - 1;
 
 	s->valid = 1;
-	s->have_metadata = 0;
+	s->active = 0;
 	s->last_percent = 0;
 	init_rwsem(&s->lock);
 	s->table = ti->table;
@@ -506,7 +501,11 @@
 		goto bad5;
 	}
 
+	/* Metadata must only be loaded into one table at once */
+	read_snapshot_metadata(s);
+
 	/* Add snapshot to the list of snapshots for this origin */
+	/* Exceptions aren't triggered till snapshot_resume() is called */
 	if (register_snapshot(s)) {
 		r = -EINVAL;
 		ti->error = "Cannot register snapshot origin";
@@ -862,7 +861,9 @@
 {
 	struct dm_snapshot *s = (struct dm_snapshot *) ti->private;
 
-	read_snapshot_metadata(s);
+	down_write(&s->lock);
+	s->active = 1;
+	up_write(&s->lock);
 }
 
 static int snapshot_status(struct dm_target *ti, status_type_t type,
@@ -932,8 +933,8 @@
 	/* Do all the snapshots on this origin */
 	list_for_each_entry (snap, snapshots, list) {
 
-		/* Only deal with valid snapshots */
-		if (!snap->valid)
+		/* Only deal with valid and active snapshots */
+		if (!snap->valid || !snap->active)
 			continue;
 
 		/* Nothing to do if writing beyond end of snapshot */
@@ -1104,7 +1105,7 @@
 
 static struct target_type origin_target = {
 	.name    = "snapshot-origin",
-	.version = {1, 0, 1},
+	.version = {1, 1, 0},
 	.module  = THIS_MODULE,
 	.ctr     = origin_ctr,
 	.dtr     = origin_dtr,
@@ -1115,7 +1116,7 @@
 
 static struct target_type snapshot_target = {
 	.name    = "snapshot",
-	.version = {1, 0, 1},
+	.version = {1, 1, 0},
 	.module  = THIS_MODULE,
 	.ctr     = snapshot_ctr,
 	.dtr     = snapshot_dtr,
--- diff/drivers/md/dm-snap.h	2005-06-17 20:48:29.000000000 +0100
+++ source/drivers/md/dm-snap.h	2005-07-06 17:18:42.000000000 +0100
@@ -99,7 +99,9 @@
 
 	/* You can't use a snapshot if this is 0 (e.g. if full) */
 	int valid;
-	int have_metadata;
+
+	/* Origin writes don't trigger exceptions until this is set */
+	int active;
 
 	/* Used for display of table */
 	char type;