linux-kernel - Re: [PATCH v2 10/16] maple_tree: convert mas

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Message-ID: <2xqcyocypx4bpwbovxjxplc76dtns5t4qk4cc3yrejjtuzzdh3@periymnnezyg>
Date: Thu, 13 Jun 2024 10:40:28 -0400
From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
To: Sidhartha Kumar <sidhartha.kumar@...cle.com>
Cc: linux-kernel@...r.kernel.org, maple-tree@...ts.infradead.org,
        linux-mm@...ck.org, akpm@...ux-foundation.org, willy@...radead.org
Subject: Re: [PATCH v2 10/16] maple_tree: convert mas_insert() to preallocate
 nodes

* Sidhartha Kumar <sidhartha.kumar@...cle.com> [240607 14:53]:
> By setting the store type in mas_insert(), we no longer need to use
> mas_wr_modify() to determine the correct store function to use. Instead,
> set the store type and call mas_wr_store_entry(). Also, pass in the
> requested gfp flags to mas_insert() so they can be passed to the call to
> mas_wr_preallocate().

This can be done without passing in the gfp flags as it was done before
by using the same flags as before (GFP_KERNEL).  However the only user
already has the gfp flags to use, so this makes sense.

We may need to add a _gfp() version in the future, but most users want
to mas_store() vs mas_insert(), so I'm fine with this change.

> 
> Signed-off-by: Sidhartha Kumar <sidhartha.kumar@...cle.com>
> ---
>  lib/maple_tree.c | 33 ++++++++++++++++-----------------
>  1 file changed, 16 insertions(+), 17 deletions(-)
> 
> diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> index 2c42e99c400c..c37bfac4f622 100644
> --- a/lib/maple_tree.c
> +++ b/lib/maple_tree.c
> @@ -4442,11 +4442,12 @@ static inline void mas_wr_preallocate(struct ma_wr_state *wr_mas, void *entry, g
>   * mas_insert() - Internal call to insert a value
>   * @mas: The maple state
>   * @entry: The entry to store
> + * @gfp: The GFP_FLAGS to use for allocations
>   *
>   * Return: %NULL or the contents that already exists at the requested index
>   * otherwise.  The maple state needs to be checked for error conditions.
>   */
> -static inline void *mas_insert(struct ma_state *mas, void *entry)
> +static inline void *mas_insert(struct ma_state *mas, void *entry, gfp_t gfp)
>  {
>  	MA_WR_STATE(wr_mas, mas, entry);
>  
> @@ -4468,26 +4469,24 @@ static inline void *mas_insert(struct ma_state *mas, void *entry)
>  	if (wr_mas.content)
>  		goto exists;
>  
> -	if (mas_is_none(mas) || mas_is_ptr(mas)) {
> -		mas_store_root(mas, entry);
> +	mas_wr_preallocate(&wr_mas, entry, gfp);
> +	if (mas_is_err(mas))
>  		return NULL;
> -	}
>  
>  	/* spanning writes always overwrite something */
> -	if (!mas_wr_walk(&wr_mas))
> +	if (mas->store_type == wr_spanning_store)
>  		goto exists;
>  
>  	/* At this point, we are at the leaf node that needs to be altered. */
> -	wr_mas.offset_end = mas->offset;
> -	wr_mas.end_piv = wr_mas.r_max;
> -
> -	if (wr_mas.content || (mas->last > wr_mas.r_max))
> -		goto exists;
> +	if (mas->store_type != wr_new_root && mas->store_type != wr_store_root) {
> +		wr_mas.offset_end = mas->offset;
> +		wr_mas.end_piv = wr_mas.r_max;
>  
> -	if (!entry)
> -		return NULL;
> +		if (wr_mas.content || (mas->last > wr_mas.r_max))
> +			goto exists;
> +	}
>  
> -	mas_wr_modify(&wr_mas);
> +	mas_wr_store_entry(&wr_mas);
>  	return wr_mas.content;
>  
>  exists:
> @@ -4532,7 +4531,7 @@ int mas_alloc_cyclic(struct ma_state *mas, unsigned long *startp,
>  		return ret;
>  
>  	do {
> -		mas_insert(mas, entry);
> +		mas_insert(mas, entry, gfp);
>  	} while (mas_nomem(mas, gfp));
>  	if (mas_is_err(mas))
>  		return xa_err(mas->node);
> @@ -6536,7 +6535,7 @@ int mtree_insert_range(struct maple_tree *mt, unsigned long first,
>  
>  	mtree_lock(mt);
>  retry:
> -	mas_insert(&ms, entry);
> +	mas_insert(&ms, entry, gfp);
>  	if (mas_nomem(&ms, gfp))
>  		goto retry;
>  
> @@ -6585,7 +6584,7 @@ int mtree_alloc_range(struct maple_tree *mt, unsigned long *startp,
>  	if (ret)
>  		goto unlock;
>  
> -	mas_insert(&mas, entry);
> +	mas_insert(&mas, entry, gfp);
>  	/*
>  	 * mas_nomem() may release the lock, causing the allocated area
>  	 * to be unavailable, so try to allocate a free area again.
> @@ -6667,7 +6666,7 @@ int mtree_alloc_rrange(struct maple_tree *mt, unsigned long *startp,
>  	if (ret)
>  		goto unlock;
>  
> -	mas_insert(&mas, entry);
> +	mas_insert(&mas, entry, gfp);
>  	/*
>  	 * mas_nomem() may release the lock, causing the allocated area
>  	 * to be unavailable, so try to allocate a free area again.
> -- 
> 2.45.2
>