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ext4: simplify the code of mb_find_order_for_block 

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>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Link: https://lore.kernel.org/r/1604764698-4269-3-git-send-email-brookxu@tencent.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Chunguang Xu 2020-11-07 23:58:13 +08:00 committed by Theodore Ts'o
parent 6bd97bf273
commit ce3cca3374
1 changed files with 3 additions and 7 deletions
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10
fs/ext4/mballoc.c
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@ -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) static int mb_find_order_for_block(struct ext4_buddy *e4b, int block)
{ {
int order = 1; int order = 1, max;
int bb_incr = 1 << (e4b->bd_blkbits - 1);
void *bb; void *bb;
BUG_ON(e4b->bd_bitmap == e4b->bd_buddy); BUG_ON(e4b->bd_bitmap == e4b->bd_buddy);
BUG_ON(block >= (1 << (e4b->bd_blkbits + 3))); BUG_ON(block >= (1 << (e4b->bd_blkbits + 3)));
bb = e4b->bd_buddy;
while (order <= e4b->bd_blkbits + 1) { while (order <= e4b->bd_blkbits + 1) {
block = block >> 1; bb = mb_find_buddy(e4b, order, &max);
if (!mb_test_bit(block, bb)) { if (!mb_test_bit(block >> order, bb)) {
/* this block is part of buddy of order 'order' */ /* this block is part of buddy of order 'order' */
return order; return order;
} }
bb += bb_incr;
bb_incr >>= 1;
order++; order++;
} }
return 0; return 0;