[PATCH 2/4] mm: don't cast ->readpage to filler_t for do_read_cache_page

[Christoph Hellwig]

We can just pass a NULL filler and do the right thing inside of
do_read_cache_page based on the NULL parameter.

Signed-off-by: Christoph Hellwig <h...@lst.de>
---
 include/linux/pagemap.h |  3 +--
 mm/filemap.c            | 10 ++++++----
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index bcf909d0de5f..f52c3a2074cd 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -386,8 +386,7 @@ extern int read_cache_pages(struct address_space *mapping,
 static inline struct page *read_mapping_page(struct address_space *mapping,
                                pgoff_t index, void *data)
 {
-       filler_t *filler = (filler_t *)mapping->a_ops->readpage;
-       return read_cache_page(mapping, index, filler, data);
+       return read_cache_page(mapping, index, NULL, data);
 }
 
 /*
diff --git a/mm/filemap.c b/mm/filemap.c
index a2fc59f56f50..51f5b02c299a 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2866,7 +2866,11 @@ static struct page *do_read_cache_page(struct 
address_space *mapping,
                }
 
 filler:
-               err = filler(data, page);
+               if (filler)
+                       err = filler(data, page);
+               else
+                       err = mapping->a_ops->readpage(data, page);
+
                if (err < 0) {
                        put_page(page);
                        return ERR_PTR(err);
@@ -2978,9 +2982,7 @@ struct page *read_cache_page_gfp(struct address_space 
*mapping,
                                pgoff_t index,
                                gfp_t gfp)
 {
-       filler_t *filler = (filler_t *)mapping->a_ops->readpage;
-
-       return do_read_cache_page(mapping, index, filler, NULL, gfp);
+       return do_read_cache_page(mapping, index, NULL, NULL, gfp);
 }
 EXPORT_SYMBOL(read_cache_page_gfp);
 
-- 
2.20.1