On Oct 21, 2020, at 3:15 AM, Chunguang Xu <brookxu.cn@xxxxxxxxx> wrote:
>
> From: Chunguang Xu <brookxu@xxxxxxxxxxx>
>
> 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@xxxxxxxxxxx>
Removing lines is always good.
Reviewed-by: Andreas Dilger <adilger@xxxxxxxxx>
> ---
> 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
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