Fix dspace underflow bug

Since spa_dspace accounts only normal allocation class space,
spa_nonallocating_dspace should do the same.  Otherwise we may get
negative overflow or respective assertion spa_update_dspace() if
removed special/dedup vdev is bigger than all normal class space.

Reviewed-by: Alexander Motin <[email protected]>
Reviewed-by: Allan Jude <[email protected]>
Signed-off-by: Paul Dagnelie <[email protected]>
Closes openzfs#17183
(cherry picked from commit 367d34b)

Author: pcd1193182

include/sys/vdev.h

@@ -100,6 +100,7 @@ extern boolean_t vdev_replace_in_progress(vdev_t *vdev);
 extern void vdev_hold(vdev_t *);
 extern void vdev_rele(vdev_t *);
 
+void vdev_update_nonallocating_space(vdev_t *vd, boolean_t add);
 extern int vdev_metaslab_init(vdev_t *vd, uint64_t txg);
 extern void vdev_metaslab_fini(vdev_t *vd);
 extern void vdev_metaslab_set_size(vdev_t *);

module/zfs/vdev.c

@@ -1516,6 +1516,25 @@ vdev_metaslab_group_create(vdev_t *vd)
 	}
 }
 
+void
+vdev_update_nonallocating_space(vdev_t *vd, boolean_t add)
+{
+	spa_t *spa = vd->vdev_spa;
+
+	if (vd->vdev_mg->mg_class != spa_normal_class(spa))
+		return;
+
+	uint64_t raw_space = metaslab_group_get_space(vd->vdev_mg);
+	uint64_t dspace = spa_deflate(spa) ?
+	    vdev_deflated_space(vd, raw_space) : raw_space;
+	if (add) {
+		spa->spa_nonallocating_dspace += dspace;
+	} else {
+		ASSERT3U(spa->spa_nonallocating_dspace, >=, dspace);
+		spa->spa_nonallocating_dspace -= dspace;
+	}
+}
+
 int
 vdev_metaslab_init(vdev_t *vd, uint64_t txg)
 {
@@ -1627,8 +1646,7 @@ vdev_metaslab_init(vdev_t *vd, uint64_t txg)
 	 */
 	if (vd->vdev_noalloc) {
 		/* track non-allocating vdev space */
-		spa->spa_nonallocating_dspace += spa_deflate(spa) ?
-		    vd->vdev_stat.vs_dspace : vd->vdev_stat.vs_space;
+		vdev_update_nonallocating_space(vd, B_TRUE);
 	} else if (!expanding) {
 		metaslab_group_activate(vd->vdev_mg);
 		if (vd->vdev_log_mg != NULL)

module/zfs/vdev_removal.c

@@ -172,19 +172,14 @@ static void
 vdev_activate(vdev_t *vd)
 {
 	metaslab_group_t *mg = vd->vdev_mg;
-	spa_t *spa = vd->vdev_spa;
-	uint64_t vdev_space = spa_deflate(spa) ?
-	    vd->vdev_stat.vs_dspace : vd->vdev_stat.vs_space;
 
 	ASSERT(!vd->vdev_islog);
 	ASSERT(vd->vdev_noalloc);
 
 	metaslab_group_activate(mg);
 	metaslab_group_activate(vd->vdev_log_mg);
 
-	ASSERT3U(spa->spa_nonallocating_dspace, >=, vdev_space);
-
-	spa->spa_nonallocating_dspace -= vdev_space;
+	vdev_update_nonallocating_space(vd, B_FALSE);
 
 	vd->vdev_noalloc = B_FALSE;
 }
@@ -256,8 +251,7 @@ vdev_passivate(vdev_t *vd, uint64_t *txg)
 		return (error);
 	}
 
-	spa->spa_nonallocating_dspace += spa_deflate(spa) ?
-	    vd->vdev_stat.vs_dspace : vd->vdev_stat.vs_space;
+	vdev_update_nonallocating_space(vd, B_TRUE);
 	vd->vdev_noalloc = B_TRUE;
 
 	return (0);
@@ -1370,20 +1364,15 @@ vdev_remove_complete(spa_t *spa)
 	ASSERT3P(vd->vdev_autotrim_thread, ==, NULL);
 	vdev_rebuild_stop_wait(vd);
 	ASSERT3P(vd->vdev_rebuild_thread, ==, NULL);
-	uint64_t vdev_space = spa_deflate(spa) ?
-	    vd->vdev_stat.vs_dspace : vd->vdev_stat.vs_space;
 
 	sysevent_t *ev = spa_event_create(spa, vd, NULL,
 	    ESC_ZFS_VDEV_REMOVE_DEV);
 
 	zfs_dbgmsg("finishing device removal for vdev %llu in txg %llu",
 	    (u_longlong_t)vd->vdev_id, (u_longlong_t)txg);
 
-	ASSERT3U(0, !=, vdev_space);
-	ASSERT3U(spa->spa_nonallocating_dspace, >=, vdev_space);
-
 	/* the vdev is no longer part of the dspace */
-	spa->spa_nonallocating_dspace -= vdev_space;
+	vdev_update_nonallocating_space(vd, B_FALSE);
 
 	/*
 	 * Discard allocation state.