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From:   Huang Ying <ying.huang@intel.com>
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Huang Ying <ying.huang@intel.com>,
        Yosry Ahmed <yosryahmed@google.com>,
        David Hildenbrand <david@redhat.com>,
        Hugh Dickins <hughd@google.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Matthew Wilcox <willy@infradead.org>,
        Michal Hocko <mhocko@suse.com>,
        Minchan Kim <minchan@kernel.org>,
        Tim Chen <tim.c.chen@linux.intel.com>,
        Yang Shi <shy828301@gmail.com>, Yu Zhao <yuzhao@google.com>,
        Chris Li <chrisl@kernel.org>
Subject: [PATCH -V3 1/5] swap: Remove get/put_swap_device() in __swap_count()
Date:   Mon, 29 May 2023 14:13:51 +0800
Message-Id: <20230529061355.125791-2-ying.huang@intel.com>
In-Reply-To: <20230529061355.125791-1-ying.huang@intel.com>
References: <20230529061355.125791-1-ying.huang@intel.com>
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get/put_swap_device() are added to __swap_count() in commit
eb085574a752 ("mm, swap: fix race between swapoff and some swap
operations").  Later, in commit 2799e77529c2 ("swap: fix
do_swap_page() race with swapoff"), get/put_swap_device() are added to
do_swap_page().  And they enclose the only call site of
__swap_count().  So, it's safe to remove get/put_swap_device() in
__swap_count() now.

Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Chris Li <chrisl@kernel.org>
---
 mm/swapfile.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 274bbf797480..8419cba9c192 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1432,16 +1432,10 @@ void swapcache_free_entries(swp_entry_t *entries, int n)
 
 int __swap_count(swp_entry_t entry)
 {
-	struct swap_info_struct *si;
+	struct swap_info_struct *si = swp_swap_info(entry);
 	pgoff_t offset = swp_offset(entry);
-	int count = 0;
 
-	si = get_swap_device(entry);
-	if (si) {
-		count = swap_count(si->swap_map[offset]);
-		put_swap_device(si);
-	}
-	return count;
+	return swap_count(si->swap_map[offset]);
 }
 
 /*
-- 
2.39.2