linux-ext4 - [PATCH 3/8] ext4: simplify the code of mb_find_order_for

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Date:   Wed, 21 Oct 2020 17:15:23 +0800
From:   Chunguang Xu <brookxu.cn@...il.com>
To:     tytso@....edu, adilger.kernel@...ger.ca
Cc:     linux-ext4@...r.kernel.org
Subject: [PATCH 3/8] ext4: simplify the code of mb_find_order_for_block

From: Chunguang Xu <brookxu@...cent.com>

The code of mb_find_order_for_block is a bit obscure, but we can
simplify it with mb_find_buddy(), make the code more concise.

Signed-off-by: Chunguang Xu <brookxu@...cent.com>
---
 fs/ext4/mballoc.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 22301f3..2efb489 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -1289,22 +1289,18 @@ static void ext4_mb_unload_buddy(struct ext4_buddy *e4b)
 
 static int mb_find_order_for_block(struct ext4_buddy *e4b, int block)
 {
-	int order = 1;
-	int bb_incr = 1 << (e4b->bd_blkbits - 1);
+	int order = 1, max;
 	void *bb;
 
 	BUG_ON(e4b->bd_bitmap == e4b->bd_buddy);
 	BUG_ON(block >= (1 << (e4b->bd_blkbits + 3)));
 
-	bb = e4b->bd_buddy;
 	while (order <= e4b->bd_blkbits + 1) {
-		block = block >> 1;
-		if (!mb_test_bit(block, bb)) {
+		bb = mb_find_buddy(e4b, order, &max);
+		if (!mb_test_bit(block >> order, bb)) {
 			/* this block is part of buddy of order 'order' */
 			return order;
 		}
-		bb += bb_incr;
-		bb_incr >>= 1;
 		order++;
 	}
 	return 0;
-- 
1.8.3.1