From 2bf5eb2a7c22fc3dd011fda2722fd369b1c4608b Mon Sep 17 00:00:00 2001 From: Gou Hao Date: Mon, 13 Nov 2023 16:26:17 +0800 Subject: ext4: improving calculation of 'fe_{len|start}' in mb_find_extent() After first execution of mb_find_order_for_block(): 'fe_start' is the value of 'block' passed in mb_find_extent(). 'fe_len' is the difference between the length of order-chunk and remainder of the block divided by order-chunk. And 'next' does not require initialization after above modifications. Signed-off-by: Gou Hao Reviewed-by: Jan Kara Link: https://lore.kernel.org/r/20231113082617.11258-1-gouhao@uniontech.com Signed-off-by: Theodore Ts'o --- fs/ext4/mballoc.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-) (limited to 'fs/ext4/mballoc.c') diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 847dc0fb1573..0c69f2f8cf88 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -1957,8 +1957,7 @@ done: static int mb_find_extent(struct ext4_buddy *e4b, int block, int needed, struct ext4_free_extent *ex) { - int next = block; - int max, order; + int max, order, next; void *buddy; assert_spin_locked(ext4_group_lock_ptr(e4b->bd_sb, e4b->bd_group)); @@ -1976,16 +1975,12 @@ static int mb_find_extent(struct ext4_buddy *e4b, int block, /* find actual order */ order = mb_find_order_for_block(e4b, block); - block = block >> order; - ex->fe_len = 1 << order; - ex->fe_start = block << order; + ex->fe_len = (1 << order) - (block & ((1 << order) - 1)); + ex->fe_start = block; ex->fe_group = e4b->bd_group; - /* calc difference from given start */ - next = next - ex->fe_start; - ex->fe_len -= next; - ex->fe_start += next; + block = block >> order; while (needed > ex->fe_len && mb_find_buddy(e4b, order, &max)) { -- cgit v1.2.3-70-g09d2