switch fchmod() to fdget

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

fs/open.c

@@ -485,14 +485,13 @@ static int chmod_common(struct path *path, umode_t mode)
 
 SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
 {
-	struct file * file;
+	struct fd f = fdget(fd);
 	int err = -EBADF;
 
-	file = fget(fd);
-	if (file) {
-		audit_inode(NULL, file->f_path.dentry, 0);
-		err = chmod_common(&file->f_path, mode);
-		fput(file);
+	if (f.file) {
+		audit_inode(NULL, f.file->f_path.dentry, 0);
+		err = chmod_common(&f.file->f_path, mode);
+		fdput(f);
 	}
 	return err;
 }