On Wed, Aug 14, 2024 at 03:49:41PM +0800, Zhang Yi wrote: > Sorry, this makes me confused. How does this could prevent setting > redundant dirty bits? > > Suppose we have a 3K regular file on a filesystem with 1K block size. > In iomap_page_mkwrite(), the iter.len is 3K, if the folio size is 4K, > folio_mark_dirty() will also mark all 4 bits of ifs dirty. And then, > if we expand this file size to 4K, and this will still lead to a hole > with dirty bit set but without any block allocated/reserved. Am I > missing something? No, we still need the ifs manipulation in the loop indeed. But the filemap_dirty_folio (and the not uptodate warning) can still move outside the iterator.
