take the guts of file-to-pipe splice into a helper function

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

fs/splice.c

@@ -1002,6 +1002,23 @@ static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
 			       struct pipe_inode_info *opipe,
 			       size_t len, unsigned int flags);
 
+static long splice_file_to_pipe(struct file *in,
+			 struct pipe_inode_info *opipe,
+			 loff_t *offset,
+			 size_t len, unsigned int flags)
+{
+	long ret;
+
+	pipe_lock(opipe);
+	ret = wait_for_space(opipe, flags);
+	if (!ret)
+		ret = do_splice_to(in, offset, opipe, len, flags);
+	pipe_unlock(opipe);
+	if (ret > 0)
+		wakeup_pipe_readers(opipe);
+	return ret;
+}
+
 /*
  * Determine where to splice to/from.
  */
@@ -1081,13 +1098,7 @@ long do_splice(struct file *in, loff_t *off_in, struct file *out,
 		if (out->f_flags & O_NONBLOCK)
 			flags |= SPLICE_F_NONBLOCK;
 
-		pipe_lock(opipe);
-		ret = wait_for_space(opipe, flags);
-		if (!ret)
-			ret = do_splice_to(in, &offset, opipe, len, flags);
-		pipe_unlock(opipe);
-		if (ret > 0)
-			wakeup_pipe_readers(opipe);
+		ret = splice_file_to_pipe(in, opipe, &offset, len, flags);
 		if (!off_in)
 			in->f_pos = offset;
 		else