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Index: head/sys/kern/subr_blist.c
===================================================================
--- head/sys/kern/subr_blist.c
+++ head/sys/kern/subr_blist.c
@@ -110,6 +110,7 @@
#define bitcount64(x) __bitcount64((uint64_t)(x))
#define malloc(a,b,c) calloc(a, 1)
#define free(a,b) free(a)
+#define CTASSERT(expr)
#include <sys/blist.h>
@@ -142,6 +143,8 @@
static MALLOC_DEFINE(M_SWAP, "SWAP", "Swap space");
#endif
+CTASSERT(BLIST_BMAP_RADIX % BLIST_META_RADIX == 0);
+
/*
* For a subtree that can represent the state of up to 'radix' blocks, the
* number of leaf nodes of the subtree is L=radix/BLIST_BMAP_RADIX. If 'm'
@@ -151,17 +154,19 @@
* in the 'meta' functions that process subtrees. Since integer division
* discards remainders, we can express this computation as
* skip = (m * m**h) / (m - 1)
- * skip = (m * radix / BLIST_BMAP_RADIX) / (m - 1)
- * and if m divides BLIST_BMAP_RADIX, we can simplify further to
- * skip = radix / (BLIST_BMAP_RADIX / m * (m - 1))
- * so that a simple integer division is enough for the calculation.
+ * skip = (m * (radix / BLIST_BMAP_RADIX)) / (m - 1)
+ * and since m divides BLIST_BMAP_RADIX, we can simplify further to
+ * skip = (radix / (BLIST_BMAP_RADIX / m)) / (m - 1)
+ * skip = radix / ((BLIST_BMAP_RADIX / m) * (m - 1))
+ * so that simple integer division by a constant can safely be used for the
+ * calculation.
*/
static inline daddr_t
radix_to_skip(daddr_t radix)
{
return (radix /
- (BLIST_BMAP_RADIX / BLIST_META_RADIX * (BLIST_META_RADIX - 1)));
+ ((BLIST_BMAP_RADIX / BLIST_META_RADIX) * (BLIST_META_RADIX - 1)));
}
/*

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