bcachefs: implement eytzinger0_find_gt directly

Instead of implementing eytzinger0_find_gt() in terms of
eytzinger0_find_le() and adjusting the result, implement it directly.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/eytzinger.h b/fs/bcachefs/eytzinger.h
index a530dbcde476c90d8a51c453ba95a4956108babc..568a04b16d0938eb5ee6c7a0ebf4fa99e0efe200 100644 (file)
--- a/fs/bcachefs/eytzinger.h
+++ b/fs/bcachefs/eytzinger.h
@@ -262,20 +262,17 @@ static inline int eytzinger0_find_le(void *base, size_t nr, size_t size,
        return n - 1;
 }
 
+/* return smallest node > @search, or -1 if not found */
 static inline int eytzinger0_find_gt(void *base, size_t nr, size_t size,
                                     cmp_func_t cmp, const void *search)
 {
-       ssize_t idx = eytzinger0_find_le(base, nr, size, cmp, search);
+       void *base1 = base - size;
+       unsigned n = 1;
 
-       /*
-        * if eytitzinger0_find_le() returned -1 - no element was <= search - we
-        * want to return the first element; next/prev identities mean this work
-        * as expected
-        *
-        * similarly if find_le() returns last element, we should return -1;
-        * identities mean this all works out:
-        */
-       return eytzinger0_next(idx, nr);
+       while (n <= nr)
+               n = eytzinger1_child(n, cmp(base1 + n * size, search) <= 0);
+       n >>= __ffs(n + 1) + 1;
+       return n - 1;
 }
 
 static inline int eytzinger0_find_ge(void *base, size_t nr, size_t size,