linux-kernel - [PATCH 10/24] mm/swap: remove nr_rotate

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Date:   Mon, 20 Nov 2023 03:47:26 +0800
From:   Kairui Song <ryncsn@...il.com>
To:     linux-mm@...ck.org
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        "Huang, Ying" <ying.huang@...el.com>,
        David Hildenbrand <david@...hat.com>,
        Hugh Dickins <hughd@...gle.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Matthew Wilcox <willy@...radead.org>,
        Michal Hocko <mhocko@...e.com>, linux-kernel@...r.kernel.org,
        Kairui Song <kasong@...cent.com>
Subject: [PATCH 10/24] mm/swap: remove nr_rotate_swap and related code

From: Kairui Song <kasong@...cent.com>

No longer needed after we switched to per entry swap readhead policy.

Signed-off-by: Kairui Song <kasong@...cent.com>
---
 include/linux/swap.h |  1 -
 mm/swapfile.c        | 11 -----------
 2 files changed, 12 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 64a37819a9b3..cc83fb884757 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -454,7 +454,6 @@ extern void free_pages_and_swap_cache(struct encoded_page **, int);
 /* linux/mm/swapfile.c */
 extern atomic_long_t nr_swap_pages;
 extern long total_swap_pages;
-extern atomic_t nr_rotate_swap;
 extern bool has_usable_swap(void);
 
 /* Swap 50% full? Release swapcache more aggressively.. */
diff --git a/mm/swapfile.c b/mm/swapfile.c
index e15a6c464a38..01c3f53b6521 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -104,8 +104,6 @@ static DECLARE_WAIT_QUEUE_HEAD(proc_poll_wait);
 /* Activity counter to indicate that a swapon or swapoff has occurred */
 static atomic_t proc_poll_event = ATOMIC_INIT(0);
 
-atomic_t nr_rotate_swap = ATOMIC_INIT(0);
-
 static struct swap_info_struct *swap_type_to_swap_info(int type)
 {
 	if (type >= MAX_SWAPFILES)
@@ -2486,9 +2484,6 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
 	if (p->flags & SWP_CONTINUED)
 		free_swap_count_continuations(p);
 
-	if (!p->bdev || !bdev_nonrot(p->bdev))
-		atomic_dec(&nr_rotate_swap);
-
 	mutex_lock(&swapon_mutex);
 	spin_lock(&swap_lock);
 	spin_lock(&p->lock);
@@ -2990,7 +2985,6 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 	struct swap_cluster_info *cluster_info = NULL;
 	struct page *page = NULL;
 	struct inode *inode = NULL;
-	bool inced_nr_rotate_swap = false;
 
 	if (swap_flags & ~SWAP_FLAGS_VALID)
 		return -EINVAL;
@@ -3112,9 +3106,6 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 			cluster = per_cpu_ptr(p->percpu_cluster, cpu);
 			cluster_set_null(&cluster->index);
 		}
-	} else {
-		atomic_inc(&nr_rotate_swap);
-		inced_nr_rotate_swap = true;
 	}
 
 	error = swap_cgroup_swapon(p->type, maxpages);
@@ -3218,8 +3209,6 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 	spin_unlock(&swap_lock);
 	vfree(swap_map);
 	kvfree(cluster_info);
-	if (inced_nr_rotate_swap)
-		atomic_dec(&nr_rotate_swap);
 	if (swap_file)
 		filp_close(swap_file, NULL);
 out:
-- 
2.42.0