mirror O_APPEND and O_DIRECT into iocb->ki_flags

... avoiding write_iter/fcntl races.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/fs.h b/include/linux/fs.h
index b4aa400..b1d7db2 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -315,6 +315,8 @@
 struct writeback_control;
 
 #define IOCB_EVENTFD		(1 << 0)
+#define IOCB_APPEND		(1 << 1)
+#define IOCB_DIRECT		(1 << 2)
 
 struct kiocb {
 	struct file		*ki_filp;
@@ -329,10 +331,13 @@
 	return kiocb->ki_complete == NULL;
 }
 
+static inline int iocb_flags(struct file *file);
+
 static inline void init_sync_kiocb(struct kiocb *kiocb, struct file *filp)
 {
 	*kiocb = (struct kiocb) {
 		.ki_filp = filp,
+		.ki_flags = iocb_flags(filp),
 	};
 }
 
@@ -2779,6 +2784,16 @@
 	return (filp->f_flags & O_DIRECT) || IS_DAX(file_inode(filp));
 }
 
+static inline int iocb_flags(struct file *file)
+{
+	int res = 0;
+	if (file->f_flags & O_APPEND)
+		res |= IOCB_APPEND;
+	if (io_is_direct(file))
+		res |= IOCB_DIRECT;
+	return res;
+}
+
 static inline ino_t parent_ino(struct dentry *dentry)
 {
 	ino_t res;