fix switch_names() breakage in short-to-short case

We want ->name.len to match the resulting name on *both*
source and target

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/dcache.c

@@ -1616,8 +1616,11 @@ static void switch_names(struct dentry *dentry, struct dentry *target)
 			 */
 			memcpy(dentry->d_iname, target->d_name.name,
 					target->d_name.len + 1);
+			dentry->d_name.len = target->d_name.len;
+			return;
 		}
 	}
+	do_switch(dentry->d_name.len, target->d_name.len);
 }
 
 /*
@@ -1677,7 +1680,6 @@ already_unhashed:
 
 	/* Switch the names.. */
 	switch_names(dentry, target);
-	do_switch(dentry->d_name.len, target->d_name.len);
 	do_switch(dentry->d_name.hash, target->d_name.hash);
 
 	/* ... and switch the parents */
@@ -1787,7 +1789,6 @@ static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon)
 	struct dentry *dparent, *aparent;
 
 	switch_names(dentry, anon);
-	do_switch(dentry->d_name.len, anon->d_name.len);
 	do_switch(dentry->d_name.hash, anon->d_name.hash);
 
 	dparent = dentry->d_parent;