Re: [PATCH v5 03/10] maple_tree: Introduce interfaces __mt_dup() and mtree_dup()

[Peng Zhang]

在 2023/10/16 22:10, Matthew Wilcox 写道:
> On Mon, Oct 16, 2023 at 11:22:19AM +0800, Peng Zhang wrote:
> > +++ b/lib/maple_tree.c
> > @@ -4,6 +4,10 @@
> >    * Copyright (c) 2018-2022 Oracle Corporation
> >    * Authors: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
> >    *	    Matthew Wilcox <willy@xxxxxxxxxxxxx>
> > + *
> > + * Algorithm for duplicating Maple Tree
> > + * Copyright (c) 2023 ByteDance
> > + * Author: Peng Zhang <zhangpeng.00@xxxxxxxxxxxxx>
>
> You can't copyright an algorithm.  You can copyright the
> _implementation_ of an algorithm.  You have a significant chunk of code
> in this file, so adding your copyright is reasonable (although not
> legally required, AIUI).  Just leave out this line:
>
> + * Algorithm for duplicating Maple Tree
Okay, I will make the correction, thank you.
> > +/**
> > + * __mt_dup(): Duplicate an entire maple tree
> > + * @mt: The source maple tree
> > + * @new: The new maple tree
> > + * @gfp: The GFP_FLAGS to use for allocations
> > + *
> > + * This function duplicates a maple tree in Depth-First Search (DFS) pre-order
> > + * traversal. It uses memcopy() to copy nodes in the source tree and allocate
>
> memcpy()?
Yes, thank you for pointing this out.
> > +int __mt_dup(struct maple_tree *mt, struct maple_tree *new, gfp_t gfp)
> > +{
> > +	int ret = 0;
> > +	MA_STATE(mas, mt, 0, 0);
> > +	MA_STATE(new_mas, new, 0, 0);
> > +
> > +	mas_dup_build(&mas, &new_mas, gfp);
> > +
> > +	if (unlikely(mas_is_err(&mas))) {
> > +		ret = xa_err(mas.node);
> > +		if (ret == -ENOMEM)
> > +			mas_dup_free(&new_mas);
> > +	}
> > +
> > +	return ret;
> > +}
> > +EXPORT_SYMBOL(__mt_dup);
>
> Why does it need to be exported?
I consider __mt_dup() as a general interface for Maple Tree,
uncertain whether it will be used by certain modules in the future.
>