+ maple_tree-make-maple-state-reusable-after-mas_empty_area_rev.patch added to mm-hotfixes-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: maple_tree: make maple state reusable after mas_empty_area_rev()
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     maple_tree-make-maple-state-reusable-after-mas_empty_area_rev.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/maple_tree-make-maple-state-reusable-after-mas_empty_area_rev.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Subject: maple_tree: make maple state reusable after mas_empty_area_rev()
Date: Fri, 14 Apr 2023 10:57:26 -0400

Stop using maple state min/max for the range by passing through pointers
for those values.  This will allow the maple state to be reused without
resetting.

Also add some logic to fail out early on searching with invalid
arguments.

Link: https://lkml.kernel.org/r/20230414145728.4067069-1-Liam.Howlett@oracle.com
Fixes: 54a611b60590 ("Maple Tree: add new data structure")
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reported-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Peng Zhang <zhangpeng.00@bytedance.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 lib/maple_tree.c |   27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

--- a/lib/maple_tree.c~maple_tree-make-maple-state-reusable-after-mas_empty_area_rev
+++ a/lib/maple_tree.c
@@ -4965,7 +4965,8 @@ not_found:
  * Return: True if found in a leaf, false otherwise.
  *
  */
-static bool mas_rev_awalk(struct ma_state *mas, unsigned long size)
+static bool mas_rev_awalk(struct ma_state *mas, unsigned long size,
+		unsigned long *gap_min, unsigned long *gap_max)
 {
 	enum maple_type type = mte_node_type(mas->node);
 	struct maple_node *node = mas_mn(mas);
@@ -5030,8 +5031,8 @@ static bool mas_rev_awalk(struct ma_stat
 
 	if (unlikely(ma_is_leaf(type))) {
 		mas->offset = offset;
-		mas->min = min;
-		mas->max = min + gap - 1;
+		*gap_min = min;
+		*gap_max = min + gap - 1;
 		return true;
 	}
 
@@ -5309,6 +5310,9 @@ int mas_empty_area(struct ma_state *mas,
 	unsigned long *pivots;
 	enum maple_type mt;
 
+	if (min >= max)
+		return -EINVAL;
+
 	if (mas_is_start(mas))
 		mas_start(mas);
 	else if (mas->offset >= 2)
@@ -5363,6 +5367,9 @@ int mas_empty_area_rev(struct ma_state *
 {
 	struct maple_enode *last = mas->node;
 
+	if (min >= max)
+		return -EINVAL;
+
 	if (mas_is_start(mas)) {
 		mas_start(mas);
 		mas->offset = mas_data_end(mas);
@@ -5382,7 +5389,7 @@ int mas_empty_area_rev(struct ma_state *
 	mas->index = min;
 	mas->last = max;
 
-	while (!mas_rev_awalk(mas, size)) {
+	while (!mas_rev_awalk(mas, size, &min, &max)) {
 		if (last == mas->node) {
 			if (!mas_rewind_node(mas))
 				return -EBUSY;
@@ -5397,17 +5404,9 @@ int mas_empty_area_rev(struct ma_state *
 	if (unlikely(mas->offset == MAPLE_NODE_SLOTS))
 		return -EBUSY;
 
-	/*
-	 * mas_rev_awalk() has set mas->min and mas->max to the gap values.  If
-	 * the maximum is outside the window we are searching, then use the last
-	 * location in the search.
-	 * mas->max and mas->min is the range of the gap.
-	 * mas->index and mas->last are currently set to the search range.
-	 */
-
 	/* Trim the upper limit to the max. */
-	if (mas->max <= mas->last)
-		mas->last = mas->max;
+	if (max <= mas->last)
+		mas->last = max;
 
 	mas->index = mas->last - size + 1;
 	return 0;
_

Patches currently in -mm which might be from Liam.Howlett@oracle.com are

maple_tree-make-maple-state-reusable-after-mas_empty_area_rev.patch