spufs: fix bogosity in S_ISGID handling

clearing everything *except* S_ISGID (including the S_IFDIR, among
other things) is wrong.  Just use init_inode_owner() and be done
with that...
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/powerpc/platforms/cell/spufs/inode.c

@@ -236,10 +236,7 @@ spufs_mkdir(struct inode *dir, struct dentry *dentry, unsigned int flags,
 	if (!inode)
 		return -ENOSPC;
 
-	if (dir->i_mode & S_ISGID) {
-		inode->i_gid = dir->i_gid;
-		inode->i_mode &= S_ISGID;
-	}
+	inode_init_owner(&init_user_ns, inode, dir, mode | S_IFDIR);
 	ctx = alloc_spu_context(SPUFS_I(dir)->i_gang); /* XXX gang */
 	SPUFS_I(inode)->i_ctx = ctx;
 	if (!ctx) {
@@ -470,10 +467,7 @@ spufs_mkgang(struct inode *dir, struct dentry *dentry, umode_t mode)
 		goto out;
 
 	ret = 0;
-	if (dir->i_mode & S_ISGID) {
-		inode->i_gid = dir->i_gid;
-		inode->i_mode &= S_ISGID;
-	}
+	inode_init_owner(&init_user_ns, inode, dir, mode | S_IFDIR);
 	gang = alloc_spu_gang();
 	SPUFS_I(inode)->i_ctx = NULL;
 	SPUFS_I(inode)->i_gang = gang;