mm/swapfile.c: optimize code in setup_clusters()

In the last 'for' loop inside setup_clusters(), using two local variable
'k' and 'j' are obvisouly redundant.  Using 'j' is enough and simpler.

And also move macro SWAP_CLUSTER_COLS close to its only user
setup_clusters().

Link: https://lkml.kernel.org/r/20250205092721.9395-8-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Kairui Song <ryncsn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 08debaacbbc09434aa94d042a01af30038a651ee..cbee03aa74b8eb2b24268032e6620cb9a6524727 100644 (file)
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -3127,13 +3127,6 @@ static unsigned long read_swap_header(struct swap_info_struct *si,
        return maxpages;
 }
 
-#define SWAP_CLUSTER_INFO_COLS                                         \
-       DIV_ROUND_UP(L1_CACHE_BYTES, sizeof(struct swap_cluster_info))
-#define SWAP_CLUSTER_SPACE_COLS                                                \
-       DIV_ROUND_UP(SWAP_ADDRESS_SPACE_PAGES, SWAPFILE_CLUSTER)
-#define SWAP_CLUSTER_COLS                                              \
-       max_t(unsigned int, SWAP_CLUSTER_INFO_COLS, SWAP_CLUSTER_SPACE_COLS)
-
 static int setup_swap_map_and_extents(struct swap_info_struct *si,
                                        union swap_header *swap_header,
                                        unsigned char *swap_map,
@@ -3173,13 +3166,20 @@ static int setup_swap_map_and_extents(struct swap_info_struct *si,
        return nr_extents;
 }
 
+#define SWAP_CLUSTER_INFO_COLS                                         \
+       DIV_ROUND_UP(L1_CACHE_BYTES, sizeof(struct swap_cluster_info))
+#define SWAP_CLUSTER_SPACE_COLS                                                \
+       DIV_ROUND_UP(SWAP_ADDRESS_SPACE_PAGES, SWAPFILE_CLUSTER)
+#define SWAP_CLUSTER_COLS                                              \
+       max_t(unsigned int, SWAP_CLUSTER_INFO_COLS, SWAP_CLUSTER_SPACE_COLS)
+
 static struct swap_cluster_info *setup_clusters(struct swap_info_struct *si,
                                                union swap_header *swap_header,
                                                unsigned long maxpages)
 {
        unsigned long nr_clusters = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER);
        struct swap_cluster_info *cluster_info;
-       unsigned long i, j, k, idx;
+       unsigned long i, j, idx;
        int cpu, err = -ENOMEM;
 
        cluster_info = kvcalloc(nr_clusters, sizeof(*cluster_info), GFP_KERNEL);
@@ -3240,8 +3240,7 @@ static struct swap_cluster_info *setup_clusters(struct swap_info_struct *si,
         * Reduce false cache line sharing between cluster_info and
         * sharing same address space.
         */
-       for (k = 0; k < SWAP_CLUSTER_COLS; k++) {
-               j = k % SWAP_CLUSTER_COLS;
+       for (j = 0; j < SWAP_CLUSTER_COLS; j++) {
                for (i = 0; i < DIV_ROUND_UP(nr_clusters, SWAP_CLUSTER_COLS); i++) {
                        struct swap_cluster_info *ci;
                        idx = i * SWAP_CLUSTER_COLS + j;