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Message-ID: <3keqnxijxstmppmci46icdfr7cshskhfzdztv4lwjjbykahjdl@riniqq3ba364>
Date: Mon, 14 Oct 2024 22:04:25 -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,
richard.weiyang@...il.com
Subject: Re: [PATCH 2/2] maple_tree: refactor mas_wr_store_type()
* Sidhartha Kumar <sidhartha.kumar@...cle.com> [241011 17:44]:
> In mas_wr_store_type(), we check if new_end < mt_slots[wr_mas->type]. If
> this check fails, we know that ,after this, new_end is >= mt_min_slots.
> Checking this again when we detect a wr_node_store later in the function
> is reduntant. Because this check is part of an OR statement, the statement
> will always evaluate to true, therefore we can just get rid of it.
>
> We also refactor mas_wr_store_type() to return the store type rather
> than set it directly as it greatly cleans up the function.
>
> Suggested-by: Liam Howlett <liam.howlett@...cle.com>
> Suggested-by: Wei Yang <richard.weiyang@...il.com>
> Signed-off-by: Sidhartha <sidhartha.kumar@...cle.com>
Reviewed-by: Liam Howlett <liam.howlett@...cle.com>
> ---
>
> Hi Andrew, could you please drop
> "maple_tree: remove conditionals to detect wr_node_store" in mm-unstable
> before applying this patch
>
> lib/maple_tree.c | 72 +++++++++++++++++-------------------------------
> 1 file changed, 25 insertions(+), 47 deletions(-)
>
> diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> index b3b1d4b8126b..a5e982e482dd 100644
> --- a/lib/maple_tree.c
> +++ b/lib/maple_tree.c
> @@ -4191,24 +4191,22 @@ static inline int mas_prealloc_calc(struct ma_state *mas, void *entry)
> }
>
> /*
> - * mas_wr_store_type() - Set the store type for a given
> + * mas_wr_store_type() - Determine the store type for a given
> * store operation.
> * @wr_mas: The maple write state
> + *
> + * Return: the type of store needed for the operation
> */
> -static inline void mas_wr_store_type(struct ma_wr_state *wr_mas)
> +static inline enum store_type mas_wr_store_type(struct ma_wr_state *wr_mas)
> {
> struct ma_state *mas = wr_mas->mas;
> unsigned char new_end;
>
> - if (unlikely(mas_is_none(mas) || mas_is_ptr(mas))) {
> - mas->store_type = wr_store_root;
> - return;
> - }
> + if (unlikely(mas_is_none(mas) || mas_is_ptr(mas)))
> + return wr_store_root;
>
> - if (unlikely(!mas_wr_walk(wr_mas))) {
> - mas->store_type = wr_spanning_store;
> - return;
> - }
> + if (unlikely(!mas_wr_walk(wr_mas)))
> + return wr_spanning_store;
>
> /* At this point, we are at the leaf node that needs to be altered. */
> mas_wr_end_piv(wr_mas);
> @@ -4216,50 +4214,30 @@ static inline void mas_wr_store_type(struct ma_wr_state *wr_mas)
> mas_wr_extend_null(wr_mas);
>
> new_end = mas_wr_new_end(wr_mas);
> - if ((wr_mas->r_min == mas->index) && (wr_mas->r_max == mas->last)) {
> - mas->store_type = wr_exact_fit;
> - return;
> - }
> + if ((wr_mas->r_min == mas->index) && (wr_mas->r_max == mas->last))
> + return wr_exact_fit;
>
> - if (unlikely(!mas->index && mas->last == ULONG_MAX)) {
> - mas->store_type = wr_new_root;
> - return;
> - }
> + if (unlikely(!mas->index && mas->last == ULONG_MAX))
> + return wr_new_root;
>
> /* Potential spanning rebalance collapsing a node */
> if (new_end < mt_min_slots[wr_mas->type]) {
> - if (!mte_is_root(mas->node) && !(mas->mas_flags & MA_STATE_BULK)) {
> - mas->store_type = wr_rebalance;
> - return;
> - }
> - mas->store_type = wr_node_store;
> - return;
> + if (!mte_is_root(mas->node) && !(mas->mas_flags & MA_STATE_BULK))
> + return wr_rebalance;
> + return wr_node_store;
> }
>
> - if (new_end >= mt_slots[wr_mas->type]) {
> - mas->store_type = wr_split_store;
> - return;
> - }
> + if (new_end >= mt_slots[wr_mas->type])
> + return wr_split_store;
>
> - if (!mt_in_rcu(mas->tree) && (mas->offset == mas->end)) {
> - mas->store_type = wr_append;
> - return;
> - }
> + if (!mt_in_rcu(mas->tree) && (mas->offset == mas->end))
> + return wr_append;
>
> if ((new_end == mas->end) && (!mt_in_rcu(mas->tree) ||
> - (wr_mas->offset_end - mas->offset == 1))) {
> - mas->store_type = wr_slot_store;
> - return;
> - }
> -
> - if (mte_is_root(mas->node) || (new_end >= mt_min_slots[wr_mas->type]) ||
> - (mas->mas_flags & MA_STATE_BULK)) {
> - mas->store_type = wr_node_store;
> - return;
> - }
> + (wr_mas->offset_end - mas->offset == 1)))
> + return wr_slot_store;
>
> - mas->store_type = wr_invalid;
> - MAS_WARN_ON(mas, 1);
> + return wr_node_store;
> }
>
> /**
> @@ -4274,7 +4252,7 @@ static inline void mas_wr_preallocate(struct ma_wr_state *wr_mas, void *entry)
> int request;
>
> mas_wr_prealloc_setup(wr_mas);
> - mas_wr_store_type(wr_mas);
> + mas->store_type = mas_wr_store_type(wr_mas);
> request = mas_prealloc_calc(mas, entry);
> if (!request)
> return;
> @@ -5446,7 +5424,7 @@ void *mas_store(struct ma_state *mas, void *entry)
> * overwrite multiple entries within a self-balancing B-Tree.
> */
> mas_wr_prealloc_setup(&wr_mas);
> - mas_wr_store_type(&wr_mas);
> + mas->store_type = mas_wr_store_type(&wr_mas);
> if (mas->mas_flags & MA_STATE_PREALLOC) {
> mas_wr_store_entry(&wr_mas);
> MAS_WR_BUG_ON(&wr_mas, mas_is_err(mas));
> @@ -5549,7 +5527,7 @@ int mas_preallocate(struct ma_state *mas, void *entry, gfp_t gfp)
> int request;
>
> mas_wr_prealloc_setup(&wr_mas);
> - mas_wr_store_type(&wr_mas);
> + mas->store_type = mas_wr_store_type(&wr_mas);
> request = mas_prealloc_calc(mas, entry);
> if (!request)
> return ret;
> --
> 2.43.0
>
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