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

include/sys/vdev_impl.h

@@ -60,7 +60,7 @@ typedef int	vdev_open_func_t(vdev_t *vd, uint64_t *size, uint64_t *max_size,
     uint64_t *ashift);
 typedef void	vdev_close_func_t(vdev_t *vd);
 typedef uint64_t vdev_asize_func_t(vdev_t *vd, uint64_t psize);
-typedef int	vdev_io_start_func_t(zio_t *zio);
+typedef void	vdev_io_start_func_t(zio_t *zio);
 typedef void	vdev_io_done_func_t(zio_t *zio);
 typedef void	vdev_state_change_func_t(vdev_t *vd, int, int);
 typedef void	vdev_hold_func_t(vdev_t *vd);

include/sys/zio.h

@@ -153,9 +153,6 @@ typedef enum zio_priority {
 	ZIO_PRIORITY_NOW		/* non-queued i/os (e.g. free) */
 } zio_priority_t;
 
-#define	ZIO_PIPELINE_CONTINUE		0x100
-#define	ZIO_PIPELINE_STOP		0x101
-
 enum zio_flag {
 	/*
 	 * Flags inherited by gang, ddt, and vdev children,