linux-kernel - [PATCH 2/2] shmem: Add shmem_read_folio() and shmem_read_folio

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Date:   Mon,  6 Feb 2023 16:25:20 +0000
From:   "Matthew Wilcox (Oracle)" <willy@...radead.org>
To:     akpm@...ux-foundation.org, hughd@...gle.com, willy@...radead.org,
        markhemm@...glemail.com, rientjes@...gle.com, surenb@...gle.com,
        shakeelb@...gle.com, mhocko@...e.com, vbabka@...e.cz,
        quic_pkondeti@...cinc.com
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Charan Teja Kalla <quic_charante@...cinc.com>
Subject: [PATCH 2/2] shmem: Add shmem_read_folio() and shmem_read_folio_gfp()

These are the folio replacements for shmem_read_mapping_page()
and shmem_read_mapping_page_gfp().

Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
---
 include/linux/shmem_fs.h |  8 ++++++++
 mm/shmem.c               | 34 +++++++++++++++++++++-------------
 2 files changed, 29 insertions(+), 13 deletions(-)

diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
index d09d54be4ffd..103d1000a5a2 100644
--- a/include/linux/shmem_fs.h
+++ b/include/linux/shmem_fs.h
@@ -109,6 +109,14 @@ enum sgp_type {
 
 int shmem_get_folio(struct inode *inode, pgoff_t index, struct folio **foliop,
 		enum sgp_type sgp);
+struct folio *shmem_read_folio_gfp(struct address_space *mapping,
+		pgoff_t index, gfp_t gfp);
+
+static inline struct folio *shmem_read_folio(struct address_space *mapping,
+		pgoff_t index)
+{
+	return shmem_read_folio_gfp(mapping, index, mapping_gfp_mask(mapping));
+}
 
 static inline struct page *shmem_read_mapping_page(
 				struct address_space *mapping, pgoff_t index)
diff --git a/mm/shmem.c b/mm/shmem.c
index 28f3c699c8ce..d333deddc2b9 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -4320,9 +4320,9 @@ int shmem_zero_setup(struct vm_area_struct *vma)
 }
 
 /**
- * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags.
- * @mapping:	the page's address_space
- * @index:	the page index
+ * shmem_read_folio_gfp - read into page cache, using specified page allocation flags.
+ * @mapping:	the folio's address_space
+ * @index:	the folio index
  * @gfp:	the page allocator flags to use if allocating
  *
  * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
@@ -4334,13 +4334,12 @@ int shmem_zero_setup(struct vm_area_struct *vma)
  * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
  * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
  */
-struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
-					 pgoff_t index, gfp_t gfp)
+struct folio *shmem_read_folio_gfp(struct address_space *mapping,
+		pgoff_t index, gfp_t gfp)
 {
 #ifdef CONFIG_SHMEM
 	struct inode *inode = mapping->host;
 	struct folio *folio;
-	struct page *page;
 	int error;
 
 	BUG_ON(!shmem_mapping(mapping));
@@ -4350,18 +4349,27 @@ struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
 		return ERR_PTR(error);
 
 	folio_unlock(folio);
-	page = folio_file_page(folio, index);
+	return folio;
+#else
+	/*
+	 * The tiny !SHMEM case uses ramfs without swap
+	 */
+	return mapping_read_folio_gfp(mapping, index, gfp);
+#endif
+}
+EXPORT_SYMBOL_GPL(shmem_read_folio_gfp);
+
+struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
+					 pgoff_t index, gfp_t gfp)
+{
+	struct folio *folio = shmem_read_folio_gfp(mapping, index, gfp);
+	struct page *page = folio_file_page(folio, index);
+
 	if (PageHWPoison(page)) {
 		folio_put(folio);
 		return ERR_PTR(-EIO);
 	}
 
 	return page;
-#else
-	/*
-	 * The tiny !SHMEM case uses ramfs without swap
-	 */
-	return read_cache_page_gfp(mapping, index, gfp);
-#endif
 }
 EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);
-- 
2.35.1