vfs: export do_splice_direct() to modules

Export do_splice_direct() to modules.  Needed by overlay filesystem.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 5cf7f67..10ed65b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2456,6 +2456,9 @@
 		struct file *, loff_t *, size_t, unsigned int);
 extern ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe,
 		struct file *out, loff_t *, size_t len, unsigned int flags);
+extern long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
+		loff_t *opos, size_t len, unsigned int flags);
+
 
 extern void
 file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping);