[PATCH 02/28] mm, swap: consolidate the helper for mincore

[Kairui Song <ryncsn@gmail.com>]

From: Kairui Song <kasong@tencent.com>

mincore related logics are not used by any one else, so consolidate and
move it to mincore only to simplify the code.

Signed-off-by: Kairui Song <kasong@tencent.com>
---
 mm/mincore.c    | 50 +++++++++++++++++++++++++++++++++++++++----------
 mm/swap.h       | 10 ----------
 mm/swap_state.c | 38 -------------------------------------
 3 files changed, 40 insertions(+), 58 deletions(-)

diff --git a/mm/mincore.c b/mm/mincore.c
index 42d6c9c8da86..7ee88113d44c 100644
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -44,6 +44,36 @@ static int mincore_hugetlb(pte_t *pte, unsigned long hmask, unsigned long addr,
 	return 0;
 }
 
+static unsigned char mincore_swap(swp_entry_t entry)
+{
+	struct swap_info_struct *si;
+	struct folio *folio = NULL;
+	unsigned char present = 0;
+
+	/* There might be swapin error entries in shmem mapping. */
+	if (non_swap_entry(entry))
+		return 0;
+
+	if (!IS_ENABLED(CONFIG_SWAP)) {
+		WARN_ON_ONCE(1);
+		return 1;
+	}
+
+	/* Prevent swap device to being swapoff under us */
+	si = get_swap_device(entry);
+	if (si) {
+		folio = filemap_get_folio(swap_address_space(entry),
+					  swap_cache_index(entry));
+		put_swap_device(si);
+	}
+	if (folio) {
+		present = folio_test_uptodate(folio);
+		folio_put(folio);
+	}
+
+	return present;
+}
+
 /*
  * Later we can get more picky about what "in core" means precisely.
  * For now, simply check to see if the page is in the page cache,
@@ -61,8 +91,15 @@ static unsigned char mincore_page(struct address_space *mapping, pgoff_t index)
 	 * any other file mapping (ie. marked !present and faulted in with
 	 * tmpfs's .fault). So swapped out tmpfs mappings are tested here.
 	 */
-	folio = filemap_get_incore_folio(mapping, index);
-	if (!IS_ERR(folio)) {
+	folio = filemap_get_entry(mapping, index);
+	if (folio) {
+		if (xa_is_value(folio)) {
+			if (shmem_mapping(mapping))
+				return mincore_swap(radix_to_swp_entry(folio));
+			else
+				return 0;
+		}
+
 		present = folio_test_uptodate(folio);
 		folio_put(folio);
 	}
@@ -141,7 +178,6 @@ static int mincore_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 				vec[i] = 1;
 		} else { /* pte is a swap entry */
 			swp_entry_t entry = pte_to_swp_entry(pte);
-
 			if (non_swap_entry(entry)) {
 				/*
 				 * migration or hwpoison entries are always
@@ -149,13 +185,7 @@ static int mincore_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 				 */
 				*vec = 1;
 			} else {
-#ifdef CONFIG_SWAP
-				*vec = mincore_page(swap_address_space(entry),
-						    swap_cache_index(entry));
-#else
-				WARN_ON(1);
-				*vec = 1;
-#endif
+				*vec = mincore_swap(entry);
 			}
 		}
 		vec += step;
diff --git a/mm/swap.h b/mm/swap.h
index 521bf510ec75..4f85195ab83d 100644
--- a/mm/swap.h
+++ b/mm/swap.h
@@ -62,9 +62,6 @@ void clear_shadow_from_swap_cache(int type, unsigned long begin,
 void swapcache_clear(struct swap_info_struct *si, swp_entry_t entry, int nr);
 struct folio *swap_cache_get_folio(swp_entry_t entry,
 		struct vm_area_struct *vma, unsigned long addr);
-struct folio *filemap_get_incore_folio(struct address_space *mapping,
-		pgoff_t index);
-
 struct folio *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
 		struct vm_area_struct *vma, unsigned long addr,
 		struct swap_iocb **plug);
@@ -156,13 +153,6 @@ static inline struct folio *swap_cache_get_folio(swp_entry_t entry,
 	return NULL;
 }
 
-static inline
-struct folio *filemap_get_incore_folio(struct address_space *mapping,
-		pgoff_t index)
-{
-	return filemap_get_folio(mapping, index);
-}
-
 static inline void *get_shadow_from_swap_cache(swp_entry_t entry)
 {
 	return NULL;
diff --git a/mm/swap_state.c b/mm/swap_state.c
index ac4e0994931c..4117ea4e7afc 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -324,44 +324,6 @@ struct folio *swap_cache_get_folio(swp_entry_t entry,
 	return folio;
 }
 
-/**
- * filemap_get_incore_folio - Find and get a folio from the page or swap caches.
- * @mapping: The address_space to search.
- * @index: The page cache index.
- *
- * This differs from filemap_get_folio() in that it will also look for the
- * folio in the swap cache.
- *
- * Return: The found folio or %NULL.
- */
-struct folio *filemap_get_incore_folio(struct address_space *mapping,
-		pgoff_t index)
-{
-	swp_entry_t swp;
-	struct swap_info_struct *si;
-	struct folio *folio = filemap_get_entry(mapping, index);
-
-	if (!folio)
-		return ERR_PTR(-ENOENT);
-	if (!xa_is_value(folio))
-		return folio;
-	if (!shmem_mapping(mapping))
-		return ERR_PTR(-ENOENT);
-
-	swp = radix_to_swp_entry(folio);
-	/* There might be swapin error entries in shmem mapping. */
-	if (non_swap_entry(swp))
-		return ERR_PTR(-ENOENT);
-	/* Prevent swapoff from happening to us */
-	si = get_swap_device(swp);
-	if (!si)
-		return ERR_PTR(-ENOENT);
-	index = swap_cache_index(swp);
-	folio = filemap_get_folio(swap_address_space(swp), index);
-	put_swap_device(si);
-	return folio;
-}
-
 struct folio *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
 		struct mempolicy *mpol, pgoff_t ilx, bool *new_page_allocated,
 		bool skip_if_exists)
-- 
2.49.0