[PATCH 06/10] mm/truncate: Split invalidate_inode_page() into mapping_shrink_folio()

["Matthew Wilcox (Oracle)" <willy@infradead.org>]

Some of the callers already have the address_space and can avoid calling
folio_mapping() and checking if the folio was already truncated.  Also
add kernel-doc and fix the return type (in case we ever support folios
larger than 4TB).

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/linux/mm.h  |  1 -
 mm/internal.h       |  1 +
 mm/memory-failure.c |  4 ++--
 mm/truncate.c       | 34 +++++++++++++++++++++++-----------
 4 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 4637368d9455..53b301dc5c14 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1853,7 +1853,6 @@ extern void truncate_setsize(struct inode *inode, loff_t newsize);
 void pagecache_isize_extended(struct inode *inode, loff_t from, loff_t to);
 void truncate_pagecache_range(struct inode *inode, loff_t offset, loff_t end);
 int generic_error_remove_page(struct address_space *mapping, struct page *page);
-int invalidate_inode_page(struct page *page);
 
 #ifdef CONFIG_MMU
 extern vm_fault_t handle_mm_fault(struct vm_area_struct *vma,
diff --git a/mm/internal.h b/mm/internal.h
index b7a2195c12b1..927a17d58b85 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -100,6 +100,7 @@ void filemap_free_folio(struct address_space *mapping, struct folio *folio);
 int truncate_inode_folio(struct address_space *mapping, struct folio *folio);
 bool truncate_inode_partial_folio(struct folio *folio, loff_t start,
 		loff_t end);
+long invalidate_inode_page(struct page *page);
 
 /**
  * folio_evictable - Test whether a folio is evictable.
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 97a9ed8f87a9..0b72a936b8dd 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -2139,7 +2139,7 @@ static bool isolate_page(struct page *page, struct list_head *pagelist)
  */
 static int __soft_offline_page(struct page *page)
 {
-	int ret = 0;
+	long ret = 0;
 	unsigned long pfn = page_to_pfn(page);
 	struct page *hpage = compound_head(page);
 	char const *msg_page[] = {"page", "hugepage"};
@@ -2196,7 +2196,7 @@ static int __soft_offline_page(struct page *page)
 			if (!list_empty(&pagelist))
 				putback_movable_pages(&pagelist);
 
-			pr_info("soft offline: %#lx: %s migration failed %d, type %pGp\n",
+			pr_info("soft offline: %#lx: %s migration failed %ld, type %pGp\n",
 				pfn, msg_page[huge], ret, &page->flags);
 			if (ret > 0)
 				ret = -EBUSY;
diff --git a/mm/truncate.c b/mm/truncate.c
index 8aa86e294775..b1bdc61198f6 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -273,18 +273,9 @@ int generic_error_remove_page(struct address_space *mapping, struct page *page)
 }
 EXPORT_SYMBOL(generic_error_remove_page);
 
-/*
- * Safely invalidate one page from its pagecache mapping.
- * It only drops clean, unused pages. The page must be locked.
- *
- * Returns 1 if the page is successfully invalidated, otherwise 0.
- */
-int invalidate_inode_page(struct page *page)
+static long mapping_shrink_folio(struct address_space *mapping,
+		struct folio *folio)
 {
-	struct folio *folio = page_folio(page);
-	struct address_space *mapping = folio_mapping(folio);
-	if (!mapping)
-		return 0;
 	if (folio_test_dirty(folio) || folio_test_writeback(folio))
 		return 0;
 	if (folio_ref_count(folio) > folio_nr_pages(folio) + 1)
@@ -295,6 +286,27 @@ int invalidate_inode_page(struct page *page)
 	return remove_mapping(mapping, folio);
 }
 
+/**
+ * invalidate_inode_page() - Remove an unused page from the pagecache.
+ * @page: The page to remove.
+ *
+ * Safely invalidate one page from its pagecache mapping.
+ * It only drops clean, unused pages.
+ *
+ * Context: Page must be locked.
+ * Return: The number of pages successfully removed.
+ */
+long invalidate_inode_page(struct page *page)
+{
+	struct folio *folio = page_folio(page);
+	struct address_space *mapping = folio_mapping(folio);
+
+	/* The page may have been truncated before it was locked */
+	if (!mapping)
+		return 0;
+	return mapping_shrink_folio(mapping, folio);
+}
+
 /**
  * truncate_inode_pages_range - truncate range of pages specified by start & end byte offsets
  * @mapping: mapping to truncate
-- 
2.34.1