From ef9297007e9904588682699e618c56401f61d1c2 Mon Sep 17 00:00:00 2001
From: Kari Argillander <kari.argillander@gmail.com>
Date: Thu, 2 Sep 2021 18:40:49 +0300
Subject: [Backport ef9297007e99] src: Make binary search to search
 smaller chunks in beginning

We could try to optimize algorithm to first fill just small table and
after that use bigger table all the way up to ARRAY_SIZE(offs). This
way we can use bigger search array, but not lose benefits with entry
count smaller < ARRAY_SIZE(offs).

Signed-off-by: Kari Argillander <kari.argillander@gmail.com>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
---
 src/index.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/index.c b/src/index.c
index a16256ab3e9ffd5bcc660c602194c9bd2de7cfc9..3ad1ee608e531ea7c7793e691fe706ee0a6c33a4 100644
--- a/src/index.c
+++ b/src/index.c
@@ -8,6 +8,7 @@
 #include <linux/blkdev.h>
 #include <linux/buffer_head.h>
 #include <linux/fs.h>
+#include <linux/kernel.h>
 
 #include "debug.h"
 #include "ntfs.h"
@@ -679,8 +680,9 @@ static struct NTFS_DE *hdr_find_e(const struct ntfs_index *indx,
 #ifdef NTFS3_INDEX_BINARY_SEARCH
 	struct NTFS_DE *found = NULL;
 	int min_idx = 0, mid_idx, max_idx = 0;
+	int table_size = 8;
 	int diff2;
-	u16 offs[64];
+	u16 offs[128];
 
 	if (end > 0x10000)
 		goto next;
@@ -700,7 +702,7 @@ static struct NTFS_DE *hdr_find_e(const struct ntfs_index *indx,
 		off += e_size;
 
 		max_idx++;
-		if (max_idx < ARRAY_SIZE(offs))
+		if (max_idx < table_size)
 			goto fill_table;
 
 		max_idx--;
@@ -718,6 +720,7 @@ static struct NTFS_DE *hdr_find_e(const struct ntfs_index *indx,
 				return NULL;
 
 			max_idx = 0;
+			table_size = min(table_size * 2, 128);
 			goto fill_table;
 		}
 	} else if (diff2 < 0) {
-- 
2.31.1