+ mm-swapfilec-open-code-cluster_alloc_swap.patch added to mm-unstable branch

+ mm-swapfilec-open-code-cluster_alloc_swap.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/swapfile.c: open code cluster_alloc_swap()
has been added to the -mm mm-unstable branch.  Its filename is
     mm-swapfilec-open-code-cluster_alloc_swap.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-swapfilec-open-code-cluster_alloc_swap.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: Baoquan He <bhe@redhat.com>
Subject: mm/swapfile.c: open code cluster_alloc_swap()
Date: Wed, 5 Feb 2025 17:27:21 +0800

It's only called in scan_swap_map_slots().

And also remove the stale code comment in scan_swap_map_slots() because
it's not fit for the current cluster allocation mechanism.

Link: https://lkml.kernel.org/r/20250205092721.9395-13-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Cc: Chis Li <chrisl@kernel.org>
Cc: Kairui Song <ryncsn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/swapfile.c |   38 ++++++++++----------------------------
 1 file changed, 10 insertions(+), 28 deletions(-)

--- a/mm/swapfile.c~mm-swapfilec-open-code-cluster_alloc_swap
+++ a/mm/swapfile.c
@@ -1158,39 +1158,13 @@ static void swap_range_free(struct swap_
 	swap_usage_sub(si, nr_entries);
 }
 
-static int cluster_alloc_swap(struct swap_info_struct *si,
-			     unsigned char usage, int nr,
-			     swp_entry_t slots[], int order)
-{
-	int n_ret = 0;
-
-	while (n_ret < nr) {
-		unsigned long offset = cluster_alloc_swap_entry(si, order, usage);
-
-		if (!offset)
-			break;
-		slots[n_ret++] = swp_entry(si->type, offset);
-	}
-
-	return n_ret;
-}
-
 static int scan_swap_map_slots(struct swap_info_struct *si,
 			       unsigned char usage, int nr,
 			       swp_entry_t slots[], int order)
 {
 	unsigned int nr_pages = 1 << order;
+	int n_ret = 0;
 
-	/*
-	 * We try to cluster swap pages by allocating them sequentially
-	 * in swap.  Once we've allocated SWAPFILE_CLUSTER pages this
-	 * way, however, we resort to first-free allocation, starting
-	 * a new cluster.  This prevents us from scattering swap pages
-	 * all over the entire swap partition, so that we reduce
-	 * overall disk seek times between swap pages.  -- sct
-	 * But we do now try to find an empty cluster.  -Andrea
-	 * And we let swap pages go all over an SSD partition.  Hugh
-	 */
 	if (order > 0) {
 		/*
 		 * Should not even be attempting large allocations when huge
@@ -1210,7 +1184,15 @@ static int scan_swap_map_slots(struct sw
 			return 0;
 	}
 
-	return cluster_alloc_swap(si, usage, nr, slots, order);
+	while (n_ret < nr) {
+		unsigned long offset = cluster_alloc_swap_entry(si, order, usage);
+
+		if (!offset)
+			break;
+		slots[n_ret++] = swp_entry(si->type, offset);
+	}
+
+	return n_ret;
 }
 
 static bool get_swap_device_info(struct swap_info_struct *si)
_

Patches currently in -mm which might be from bhe@redhat.com are

mm-swap_statec-fix-the-obsolete-code-comment.patch
mm-swap_statec-optimize-the-code-in-clear_shadow_from_swap_cache.patch
mm-swap-remove-swap_flag_prio_shift.patch
mm-swap-skip-scanning-cluster-range-if-its-empty-cluster.patch
mm-swap-rename-swap_is_has_cache-to-swap_only_has_cache.patch
mm-swapfilec-update-the-code-comment-above-swap_count_continued.patch
mm-swapfilec-optimize-code-in-setup_clusters.patch
mm-swap_statec-remove-the-meaningless-code-comment.patch
mm-swapfilec-remove-the-unneeded-checking.patch
mm-swap-rename-swap_swapcount-to-swap_entry_swapped.patch
mm-swapfilec-remove-the-incorrect-code-comment.patch
mm-swapfilec-open-code-cluster_alloc_swap.patch