Illumos #5244 - zio pipeline callers should explicitly invoke next stage

5244 zio pipeline callers should explicitly invoke next stage
Reviewed by: Adam Leventhal <ahl@delphix.com>
Reviewed by: Alex Reece <alex.reece@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Richard Elling <richard.elling@gmail.com>
Reviewed by: Dan McDonald <danmcd@omniti.com>
Reviewed by: Steven Hartland <killing@multiplay.co.uk>
Approved by: Gordon Ross <gwr@nexenta.com>

References:
  https://www.illumos.org/issues/5244
  https://github.com/illumos/illumos-gate/commit/738f37b

Porting Notes:

1. The unported "2932 support crash dumps to raidz, etc. pools"
   caused a merge conflict due to a copyright difference in
   module/zfs/vdev_raidz.c.
2. The unported "4128 disks in zpools never go away when pulled"
   and additional Linux-specific changes caused merge conflicts in
   module/zfs/vdev_disk.c.

Ported-by: Richard Yao <richard.yao@clusterhq.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2828

module/zfs/vdev_mirror.c

@@ -24,7 +24,7 @@
  */
 
 /*
- * Copyright (c) 2013 by Delphix. All rights reserved.
+ * Copyright (c) 2012, 2014 by Delphix. All rights reserved.
  */
 
 #include <sys/zfs_context.h>
@@ -327,7 +327,7 @@ vdev_mirror_child_select(zio_t *zio)
 	return (-1);
 }
 
-static int
+static void
 vdev_mirror_io_start(zio_t *zio)
 {
 	mirror_map_t *mm;
@@ -352,7 +352,8 @@ vdev_mirror_io_start(zio_t *zio)
 				    zio->io_type, zio->io_priority, 0,
 				    vdev_mirror_scrub_done, mc));
 			}
-			return (ZIO_PIPELINE_CONTINUE);
+			zio_execute(zio);
+			return;
 		}
 		/*
 		 * For normal reads just pick one child.
@@ -378,7 +379,7 @@ vdev_mirror_io_start(zio_t *zio)
 		c++;
 	}
 
-	return (ZIO_PIPELINE_CONTINUE);
+	zio_execute(zio);
 }
 
 static int