bcachefs: convert eytzinger sort to be 1-based (2)

In this second step, transform the eytzinger indexes i, j, and k in
eytzinger1_sort_r() from 0-based to 1-based.  This step looks a bit
messy, but the resulting code is slightly better.

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

1 files changed, 21 insertions, 21 deletions

diff --git a/fs/bcachefs/eytzinger.c b/fs/bcachefs/eytzinger.c
index 4fe02c93bfb3..0e742555cb0a 100644
--- a/fs/bcachefs/eytzinger.c
+++ b/fs/bcachefs/eytzinger.c
@@ -171,7 +171,7 @@ static void eytzinger1_sort_r(void *base1, size_t n, size_t size,
 			      swap_r_func_t swap_func,
 			      const void *priv)
 {
-	int i, j, k;
+	unsigned i, j, k;
 
 	/* called from 'sort' without swap function, let's pick the default */
 	if (swap_func == SWAP_WRAPPER && !((struct wrapper *)priv)->swap_func)
@@ -187,46 +187,46 @@ static void eytzinger1_sort_r(void *base1, size_t n, size_t size,
 	}
 
 	/* heapify */
-	for (i = n / 2 - 1; i >= 0; --i) {
+	for (i = n / 2; i >= 1; --i) {
 		/* Find the sift-down path all the way to the leaves. */
-		for (j = i; k = j * 2 + 1, k + 1 < n;)
-			j = eytzinger1_do_cmp(base1, n, size, cmp_func, priv, k + 1, k + 2) > 0 ? k : k + 1;
+		for (j = i; k = j * 2, k < n;)
+			j = eytzinger1_do_cmp(base1, n, size, cmp_func, priv, k, k + 1) > 0 ? k : k + 1;
 
 		/* Special case for the last leaf with no sibling. */
-		if (j * 2 + 2 == n)
-			j = j * 2 + 1;
+		if (j * 2 == n)
+			j *= 2;
 
 		/* Backtrack to the correct location. */
-		while (j != i && eytzinger1_do_cmp(base1, n, size, cmp_func, priv, i + 1, j + 1) >= 0)
-			j = (j - 1) / 2;
+		while (j != i && eytzinger1_do_cmp(base1, n, size, cmp_func, priv, i, j) >= 0)
+			j /= 2;
 
 		/* Shift the element into its correct place. */
 		for (k = j; j != i;) {
-			j = (j - 1) / 2;
-			eytzinger1_do_swap(base1, n, size, swap_func, priv, j + 1, k + 1);
+			j /= 2;
+			eytzinger1_do_swap(base1, n, size, swap_func, priv, j, k);
 		}
 	}
 
 	/* sort */
-	for (i = n - 1; i > 0; --i) {
-		eytzinger1_do_swap(base1, n, size, swap_func, priv, 1, i + 1);
+	for (i = n; i > 1; --i) {
+		eytzinger1_do_swap(base1, n, size, swap_func, priv, 1, i);
 
 		/* Find the sift-down path all the way to the leaves. */
-		for (j = 0; k = j * 2 + 1, k + 1 < i;)
-			j = eytzinger1_do_cmp(base1, n, size, cmp_func, priv, k + 1, k + 2) > 0 ? k : k + 1;
+		for (j = 1; k = j * 2, k + 1 < i;)
+			j = eytzinger1_do_cmp(base1, n, size, cmp_func, priv, k, k + 1) > 0 ? k : k + 1;
 
 		/* Special case for the last leaf with no sibling. */
-		if (j * 2 + 2 == i)
-			j = j * 2 + 1;
+		if (j * 2 + 1 == i)
+			j *= 2;
 
 		/* Backtrack to the correct location. */
-		while (j && eytzinger1_do_cmp(base1, n, size, cmp_func, priv, 1, j + 1) >= 0)
-			j = (j - 1) / 2;
+		while (j >= 1 && eytzinger1_do_cmp(base1, n, size, cmp_func, priv, 1, j) >= 0)
+			j /= 2;
 
 		/* Shift the element into its correct place. */
-		for (k = j; j;) {
-			j = (j - 1) / 2;
-			eytzinger1_do_swap(base1, n, size, swap_func, priv, j + 1, k + 1);
+		for (k = j; j > 1;) {
+			j /= 2;
+			eytzinger1_do_swap(base1, n, size, swap_func, priv, j, k);
 		}
 	}
 }