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From:   Kefeng Wang <wangkefeng.wang@huawei.com>
To:     Andrew Morton <akpm@linux-foundation.org>
CC:     <linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>,
        Matthew Wilcox <willy@infradead.org>,
        David Hildenbrand <david@redhat.com>,
        <linux-s390@vger.kernel.org>,
        Kefeng Wang <wangkefeng.wang@huawei.com>
Subject: [PATCH v2 01/10] mm: swap: introduce pfn_swap_entry_to_folio()
Date:   Sat, 4 Nov 2023 11:55:13 +0800
Message-ID: <20231104035522.2418660-2-wangkefeng.wang@huawei.com>
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Introduce a new pfn_swap_entry_to_folio(), it is similar to
pfn_swap_entry_to_page(), but return a folio, which allow us
to completely replace the struct page variables with struct
folio variables.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 include/linux/swapops.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index bff1e8d97de0..85cb84e4be95 100644
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h
@@ -468,6 +468,19 @@ static inline struct page *pfn_swap_entry_to_page(swp_entry_t entry)
 	return p;
 }
 
+static inline struct folio *pfn_swap_entry_to_folio(swp_entry_t entry)
+{
+	struct folio *folio = pfn_folio(swp_offset_pfn(entry));
+
+	/*
+	 * Any use of migration entries may only occur while the
+	 * corresponding folio is locked
+	 */
+	BUG_ON(is_migration_entry(entry) && !folio_test_locked(folio));
+
+	return folio;
+}
+
 /*
  * A pfn swap entry is a special type of swap entry that always has a pfn stored
  * in the swap offset. They are used to represent unaddressable device memory
-- 
2.27.0