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>

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 5b745551e7a96a117e7cace9998ef893eab79943..29dfeb043050c1c0a664473d62702b26a0d1561f 100644 (file)
--- 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;