lift sb_start_write/sb_end_write out of ->aio_write()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 2c28271..578a66e 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2223,6 +2223,20 @@
 	return f->f_inode;
 }
 
+static inline void file_start_write(struct file *file)
+{
+	if (!S_ISREG(file_inode(file)->i_mode))
+		return;
+	__sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, true);
+}
+
+static inline void file_end_write(struct file *file)
+{
+	if (!S_ISREG(file_inode(file)->i_mode))
+		return;
+	__sb_end_write(file_inode(file)->i_sb, SB_FREEZE_WRITE);
+}
+
 /*
  * get_write_access() gets write permission for a file.
  * put_write_access() releases this write permission.