fs: Change the type of filler_t

By making filler_t the same as read_folio, we can use the same function
for both in gfs2.  We can push the use of folios down one more level
in jffs2 and nfs.  We also increase type safety for future users of the
various read_cache_page() family of functions by forcing the parameter
to be a pointer to struct file (or NULL).

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com>

1 files changed, 20 insertions, 20 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index 079f8cca7959..81a0ed08a82c 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3483,7 +3483,7 @@ EXPORT_SYMBOL(generic_file_mmap);
 EXPORT_SYMBOL(generic_file_readonly_mmap);
 
 static struct folio *do_read_cache_folio(struct address_space *mapping,
-		pgoff_t index, filler_t filler, void *data, gfp_t gfp)
+		pgoff_t index, filler_t filler, struct file *file, gfp_t gfp)
 {
 	struct folio *folio;
 	int err;
@@ -3504,9 +3504,9 @@ repeat:
 
 filler:
 		if (filler)
-			err = filler(data, &folio->page);
+			err = filler(file, folio);
 		else
-			err = mapping->a_ops->read_folio(data, folio);
+			err = mapping->a_ops->read_folio(file, folio);
 
 		if (err < 0) {
 			folio_put(folio);
@@ -3557,44 +3557,44 @@ out:
 }
 
 /**
- * read_cache_folio - read into page cache, fill it if needed
- * @mapping:	the page's address_space
- * @index:	the page index
- * @filler:	function to perform the read
- * @data:	first arg to filler(data, page) function, often left as NULL
- *
- * Read into the page cache. If a page already exists, and PageUptodate() is
- * not set, try to fill the page and wait for it to become unlocked.
+ * read_cache_folio - Read into page cache, fill it if needed.
+ * @mapping: The address_space to read from.
+ * @index: The index to read.
+ * @filler: Function to perform the read, or NULL to use aops->read_folio().
+ * @file: Passed to filler function, may be NULL if not required.
  *
- * If the page does not get brought uptodate, return -EIO.
+ * Read one page into the page cache.  If it succeeds, the folio returned
+ * will contain @index, but it may not be the first page of the folio.
  *
- * The function expects mapping->invalidate_lock to be already held.
+ * If the filler function returns an error, it will be returned to the
+ * caller.
  *
- * Return: up to date page on success, ERR_PTR() on failure.
+ * Context: May sleep.  Expects mapping->invalidate_lock to be held.
+ * Return: An uptodate folio on success, ERR_PTR() on failure.
  */
 struct folio *read_cache_folio(struct address_space *mapping, pgoff_t index,
-		filler_t filler, void *data)
+		filler_t filler, struct file *file)
 {
-	return do_read_cache_folio(mapping, index, filler, data,
+	return do_read_cache_folio(mapping, index, filler, file,
 			mapping_gfp_mask(mapping));
 }
 EXPORT_SYMBOL(read_cache_folio);
 
 static struct page *do_read_cache_page(struct address_space *mapping,
-		pgoff_t index, filler_t *filler, void *data, gfp_t gfp)
+		pgoff_t index, filler_t *filler, struct file *file, gfp_t gfp)
 {
 	struct folio *folio;
 
-	folio = do_read_cache_folio(mapping, index, filler, data, gfp);
+	folio = do_read_cache_folio(mapping, index, filler, file, gfp);
 	if (IS_ERR(folio))
 		return &folio->page;
 	return folio_file_page(folio, index);
 }
 
 struct page *read_cache_page(struct address_space *mapping,
-				pgoff_t index, filler_t *filler, void *data)
+			pgoff_t index, filler_t *filler, struct file *file)
 {
-	return do_read_cache_page(mapping, index, filler, data,
+	return do_read_cache_page(mapping, index, filler, file,
 			mapping_gfp_mask(mapping));
 }
 EXPORT_SYMBOL(read_cache_page);