fs: simplify do_splice_from

No need for a local function pointer when we can trivial branch on the
->splice_write presence.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

fs/splice.c

@@ -852,15 +852,9 @@ EXPORT_SYMBOL(generic_splice_sendpage);
 static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
 			   loff_t *ppos, size_t len, unsigned int flags)
 {
-	ssize_t (*splice_write)(struct pipe_inode_info *, struct file *,
-				loff_t *, size_t, unsigned int);
-
 	if (out->f_op->splice_write)
-		splice_write = out->f_op->splice_write;
-	else
-		splice_write = default_file_splice_write;
-
-	return splice_write(pipe, out, ppos, len, flags);
+		return out->f_op->splice_write(pipe, out, ppos, len, flags);
+	return default_file_splice_write(pipe, out, ppos, len, flags);
 }
 
 /*