mm: remove folio_account_redirty

Fold folio_account_redirty into folio_redirty_for_writepage now
that all other users except for the also unused account_page_redirty
wrapper are gone.

Reviewed-by: Josef Bacik <[e-mail]>
Reviewed-by: Matthew Wilcox (Oracle) <[e-mail]>
Signed-off-by: Christoph Hellwig <[e-mail]>
Reviewed-by: David Sterba <[e-mail]>
Signed-off-by: David Sterba <[e-mail]>

include/linux/writeback.h

···
 			     pgoff_t start, pgoff_t end);
 
 bool filemap_dirty_folio(struct address_space *mapping, struct folio *folio);
-void folio_account_redirty(struct folio *folio);
-static inline void account_page_redirty(struct page *page)
-{
-	folio_account_redirty(page_folio(page));
-}
 bool folio_redirty_for_writepage(struct writeback_control *, struct folio *);
 bool redirty_page_for_writepage(struct writeback_control *, struct page *);
 

mm/page-writeback.c

···
 	 * write_bandwidth = ---------------------------------------------------
 	 *                                          period
 	 *
-	 * @written may have decreased due to folio_account_redirty().
+	 * @written may have decreased due to folio_redirty_for_writepage().
 	 * Avoid underflowing @bw calculation.
 	 */
 	bw = written - min(written, wb->written_stamp);
···
 EXPORT_SYMBOL(filemap_dirty_folio);
 
 /**
- * folio_account_redirty - Manually account for redirtying a page.
- * @folio: The folio which is being redirtied.
- *
- * Most filesystems should call folio_redirty_for_writepage() instead
- * of this fuction.  If your filesystem is doing writeback outside the
- * context of a writeback_control(), it can call this when redirtying
- * a folio, to de-account the dirty counters (NR_DIRTIED, WB_DIRTIED,
- * tsk->nr_dirtied), so that they match the written counters (NR_WRITTEN,
- * WB_WRITTEN) in long term. The mismatches will lead to systematic errors
- * in balanced_dirty_ratelimit and the dirty pages position control.
- */
-void folio_account_redirty(struct folio *folio)
-{
-	struct address_space *mapping = folio->mapping;
-
-	if (mapping && mapping_can_writeback(mapping)) {
-		struct inode *inode = mapping->host;
-		struct bdi_writeback *wb;
-		struct wb_lock_cookie cookie = {};
-		long nr = folio_nr_pages(folio);
-
-		wb = unlocked_inode_to_wb_begin(inode, &cookie);
-		current->nr_dirtied -= nr;
-		node_stat_mod_folio(folio, NR_DIRTIED, -nr);
-		wb_stat_mod(wb, WB_DIRTIED, -nr);
-		unlocked_inode_to_wb_end(inode, &cookie);
-	}
-}
-EXPORT_SYMBOL(folio_account_redirty);
-
-/**
  * folio_redirty_for_writepage - Decline to write a dirty folio.
  * @wbc: The writeback control.
  * @folio: The folio.
···
 bool folio_redirty_for_writepage(struct writeback_control *wbc,
 		struct folio *folio)
 {
-	bool ret;
+	struct address_space *mapping = folio->mapping;
 	long nr = folio_nr_pages(folio);
+	bool ret;
 
 	wbc->pages_skipped += nr;
-	ret = filemap_dirty_folio(folio->mapping, folio);
-	folio_account_redirty(folio);
+	ret = filemap_dirty_folio(mapping, folio);
+	if (mapping && mapping_can_writeback(mapping)) {
+		struct inode *inode = mapping->host;
+		struct bdi_writeback *wb;
+		struct wb_lock_cookie cookie = {};
 
+		wb = unlocked_inode_to_wb_begin(inode, &cookie);
+		current->nr_dirtied -= nr;
+		node_stat_mod_folio(folio, NR_DIRTIED, -nr);
+		wb_stat_mod(wb, WB_DIRTIED, -nr);
+		unlocked_inode_to_wb_end(inode, &cookie);
+	}
 	return ret;
 }
 EXPORT_SYMBOL(folio_redirty_for_writepage);