swap_pager_seek_data(): move the clipping at the object size to consumers

Reviewed by:	alc, markj
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D54219

sys/fs/tmpfs/tmpfs_vnops.c

@@ -2091,6 +2091,8 @@ tmpfs_seek_data_locked(vm_object_t obj, off_t noff)
 	vm_pindex_t p;
 
 	p = swap_pager_seek_data(obj, OFF_TO_IDX(noff));
+	if (p == OBJ_MAX_SIZE)
+		p = obj->size;
 	return (p == OFF_TO_IDX(noff) ? noff : IDX_TO_OFF(p));
 }
 

sys/vm/swap_pager.c

@@ -2479,8 +2479,6 @@ swap_pager_seek_data(vm_object_t object, vm_pindex_t pindex)
 			return (pages.index);
 		m = vm_radix_iter_step(&pages);
 	}
-	if (swap_index == OBJ_MAX_SIZE)
-		swap_index = object->size;
 	return (swap_index);
 }