Add support g_clone_bio() and g_std_done() to spawn multiple children

of a bio and correctly gather status when done.

Sponsored by:	DARPA & NAI Labs.

2 files changed, 7 insertions, 4 deletions

diff --git a/sys/geom/geom_io.c b/sys/geom/geom_io.c
index f1d21da..deb8978 100644
--- a/sys/geom/geom_io.c
+++ b/sys/geom/geom_io.c
@@ -151,6 +151,7 @@ g_clone_bio(struct bio *bp)
 		bp2->bio_offset = bp->bio_offset;
 		bp2->bio_data = bp->bio_data;
 		bp2->bio_attribute = bp->bio_attribute;
+		bp->bio_children++;	/* XXX: atomic ? */
 	}
 	g_trace(G_T_BIO, "g_clone_bio(%p) = %p", bp, bp2);
 	return(bp2);
diff --git a/sys/geom/geom_subr.c b/sys/geom/geom_subr.c
index bfb0732..45130c6 100644
--- a/sys/geom/geom_subr.c
+++ b/sys/geom/geom_subr.c
@@ -495,13 +495,15 @@ void
 g_std_done(struct bio *bp)
 {
 	struct bio *bp2;
-	int error;
 
 	bp2 = bp->bio_linkage;
-	error = bp->bio_error;
-	bp2->bio_completed = bp->bio_completed;
+	if (bp2->bio_error == 0)
+		bp2->bio_error = bp->bio_error;
+	bp2->bio_completed += bp->bio_completed;
 	g_destroy_bio(bp);
-	g_io_deliver(bp2, error);
+	bp2->bio_children--;	/* XXX: atomic ? */
+	if (bp2->bio_children == 0)
+		g_io_deliver(bp2, bp2->bio_error);
 }
 
 /* XXX: maybe this is only g_slice_spoiled */