OpenZFS 7072 - zfs fails to expand if lun added when os is in shutdow…

…n state

Authored by: George Wilson <george.wilson@delphix.com>
Reviewed by: Igor Kozhukhov <ikozhukhov@gmail.com>
Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Alex Reece <alex@delphix.com>
Approved by: Dan McDonald <danmcd@omniti.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Ported-by: George Melikov <mail@gmelikov.ru>

OpenZFS-issue: https://www.illumos.org/issues/7072
OpenZFS-commit: openzfs/openzfs@c39a2aa
Closes #5694 

Porting notes:
- vdev.c: 'vdev_get_stats' changes are moved to 'vdev_get_stats_ex'.
- vdev_disk.c: ignored, Linux specific code is different.

module/zfs/metaslab.c

@@ -413,7 +413,13 @@ metaslab_class_expandable_space(metaslab_class_t *mc)
 			continue;
 		}
 
-		space += tvd->vdev_max_asize - tvd->vdev_asize;
+		/*
+		 * Calculate if we have enough space to add additional
+		 * metaslabs. We report the expandable space in terms
+		 * of the metaslab size since that's the unit of expansion.
+		 */
+		space += P2ALIGN(tvd->vdev_max_asize - tvd->vdev_asize,
+		    1ULL << tvd->vdev_ms_shift);
 	}
 	spa_config_exit(mc->mc_spa, SCL_VDEV, FTAG);
 	return (space);

module/zfs/vdev.c

@@ -2900,6 +2900,7 @@ vdev_get_stats_ex_impl(vdev_t *vd, vdev_stat_t *vs, vdev_stat_ex_t *vsx)
 void
 vdev_get_stats_ex(vdev_t *vd, vdev_stat_t *vs, vdev_stat_ex_t *vsx)
 {
+	vdev_t *tvd = vd->vdev_top;
 	mutex_enter(&vd->vdev_stat_lock);
 	if (vs) {
 		bcopy(&vd->vdev_stat, vs, sizeof (*vs));
@@ -2909,6 +2910,17 @@ vdev_get_stats_ex(vdev_t *vd, vdev_stat_t *vs, vdev_stat_ex_t *vsx)
 		if (vd->vdev_ops->vdev_op_leaf)
 			vs->vs_rsize += VDEV_LABEL_START_SIZE +
 			    VDEV_LABEL_END_SIZE;
+		/*
+		 * Report expandable space on top-level, non-auxillary devices
+		 * only. The expandable space is reported in terms of metaslab
+		 * sized units since that determines how much space the pool
+		 * can expand.
+		 */
+		if (vd->vdev_aux == NULL && tvd != NULL) {
+			vs->vs_esize = P2ALIGN(
+			    vd->vdev_max_asize - vd->vdev_asize,
+			    1ULL << tvd->vdev_ms_shift);
+		}
 		vs->vs_esize = vd->vdev_max_asize - vd->vdev_asize;
 		if (vd->vdev_aux == NULL && vd == vd->vdev_top &&
 		    !vd->vdev_ishole) {