namei: simpler treatment of symlinks with nothing other that / in the body

Instead of saving name and branching to OK:, where we'll immediately restore
it, and call walk_component() with WALK_PUT|WALK_GET and nd->last_type being
LAST_BIND, which is equivalent to put_link(nd), err = 0, we can just treat
that the same way we'd treat procfs-style "jump" symlinks - do put_link(nd)
and move on.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

fs/namei.c

@@ -1865,11 +1865,13 @@ static int link_path_walk(const char *name, struct nameidata *nd)
 						;
 				}
 				nd->inode = nd->path.dentry->d_inode;
-				nd->stack[nd->depth - 1].name = name;
-				if (!*s)
-					goto OK;
-				name = s;
-				continue;
+				if (unlikely(!*s)) {
+					put_link(nd);
+				} else {
+					nd->stack[nd->depth - 1].name = name;
+					name = s;
+					continue;
+				}
 			}
 		}
 		if (!d_can_lookup(nd->path.dentry)) {