diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -2549,9 +2549,12 @@
 		;
 
 	if (length > 0) {
+		/*
+		 * Write out vnode metadata, e.g. indirect blocks.
+		 */
 restartsync:
 		TAILQ_FOREACH_SAFE(bp, &bo->bo_dirty.bv_hd, b_bobufs, nbp) {
-			if (bp->b_lblkno > 0)
+			if (bp->b_lblkno >= 0)
 				continue;
 			/*
 			 * Since we hold the vnode lock this should only