On Tue, Feb 14, 2023 at 04:57:09PM +0900, David Stevens wrote: > /* > - * At this point the hpage is locked and not up-to-date. > - * It's safe to insert it into the page cache, because nobody would > - * be able to map it or use it in another way until we unlock it. > + * Mark hpage as up-to-date before inserting it into the page cache to > + * prevent it from being mistaken for an fallocated but unwritten page. > + * Inserting the unfinished hpage into the page cache is safe because > + * it is locked, so nobody can map it or use it in another way until we > + * unlock it. No, that's not true. The data has to be there before we mark it uptodate. See filemap_get_pages() for example, used as part of read(). We don't lock the page unless we need to bring it uptodate ourselves.
