diff mbox series

[3/8] ext4: simplify the code of mb_find_order_for_block

Message ID 1603271728-7198-3-git-send-email-brookxu@tencent.com
State New
Headers show
Series [1/8] ext4: use ext4_assert() to replace J_ASSERT() | expand

Commit Message

Chunguang Xu Oct. 21, 2020, 9:15 a.m. UTC
From: Chunguang Xu <brookxu@tencent.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@tencent.com>
---
 fs/ext4/mballoc.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

Comments

Andreas Dilger Oct. 23, 2020, 11:07 p.m. UTC | #1
On Oct 21, 2020, at 3:15 AM, Chunguang Xu <brookxu.cn@gmail.com> wrote:
> 
> From: Chunguang Xu <brookxu@tencent.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@tencent.com>

Removing lines is always good.

Reviewed-by: Andreas Dilger <adilger@dilger.ca>

> ---
> fs/ext4/mballoc.c | 10 +++-------
> 1 file changed, 3 insertions(+), 7 deletions(-)
> 
> 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++;
> 	}

(style) this while loop is actually a for loop:

	for (order = 1; order <= e4b->bd_blkbits + 1; order++) {

Cheers, Andreas
diff mbox series

Patch

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;