Index: lib/geom/part/geom_part.c
===================================================================
--- lib/geom/part/geom_part.c
+++ lib/geom/part/geom_part.c
@@ -328,7 +328,7 @@
 	struct ggeom *gp;
 	struct gprovider *pp;
 	off_t last, size, start, new_size;
-	off_t lba, new_lba, alignment, offset;
+	off_t lba, new_lba, alignment;
 	const char *s;
 	int error, idx, has_alignment;
 
@@ -385,7 +385,6 @@
 			goto done;
 	}
 
-	offset = (pp->lg_stripeoffset / pp->lg_sectorsize) % alignment;
 	s = find_geomcfg(gp, "last");
 	if (s == NULL)
 		errx(EXIT_FAILURE, "Final block not found for geom %s",
@@ -405,37 +404,24 @@
 	start = (off_t)strtoimax(s, NULL, 0);
 	s = find_provcfg(pp, "end");
 	lba = (off_t)strtoimax(s, NULL, 0);
-	size = lba - start + 1;
 
 	pp = find_provider(gp, lba + 1);
-	if (new_size > 0 && (new_size <= size || pp == NULL)) {
-		/* The start offset may be not aligned, so we align the end
-		 * offset and then calculate the size.
-		 */
-		new_size = ALIGNDOWN(start + offset + new_size,
-		    alignment) - start - offset;
-		goto done;
-	}
-	if (pp == NULL) {
-		new_size = ALIGNDOWN(last + offset + 1, alignment) -
-		    start - offset;
-		if (new_size < size)
-			return (ENOSPC);
-	} else {
+	if (pp != NULL) {
 		s = find_provcfg(pp, "start");
 		new_lba = (off_t)strtoimax(s, NULL, 0);
-		/*
-		 * Is there any free space between current and
-		 * next providers?
-		 */
-		new_lba = ALIGNDOWN(new_lba + offset, alignment) - offset;
-		if (new_lba > lba)
-			new_size = new_lba - start;
-		else {
-			geom_deletetree(&mesh);
-			return (ENOSPC);
-		}
-	}
+		size = new_lba - start;
+	} else
+		size = last - start + 1;
+
+	/* no size specified, use it all */
+	if (new_size == 0)
+		new_size = size;
+
+	new_size = ALIGNDOWN(new_size, alignment);
+
+	/* a larger size than available was requested, use all available space */
+	if (new_size > size)
+		new_size = ALIGNDOWN(size, alignment);
 done:
 	snprintf(ssize, sizeof(ssize), "%jd", (intmax_t)new_size);
 	gctl_change_param(req, "size", -1, ssize);