fs: Move clearing of mappedtodisk to buffer.c

The mappedtodisk flag is only meaningful for buffer head based
filesystems.  It should not be cleared for other filesystems.  This allows
us to reuse the mappedtodisk flag to have other meanings in filesystems
that do not use buffer heads.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20241002040111.1023018-2-willy@infradead.org
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>

fs/buffer.c

@@ -1649,6 +1649,7 @@ void block_invalidate_folio(struct folio *folio, size_t offset, size_t length)
 	if (length == folio_size(folio))
 		filemap_release_folio(folio, 0);
 out:
+	folio_clear_mappedtodisk(folio);
 	return;
 }
 EXPORT_SYMBOL(block_invalidate_folio);

mm/truncate.c

@@ -166,7 +166,6 @@ static void truncate_cleanup_folio(struct folio *folio)
 	 * Hence dirty accounting check is placed after invalidation.
 	 */
 	folio_cancel_dirty(folio);
-	folio_clear_mappedtodisk(folio);
 }
 
 int truncate_inode_folio(struct address_space *mapping, struct folio *folio)