On Fri, Oct 04, 2024 at 04:04:28PM -0400, Goldwyn Rodrigues wrote: > Filesystems such as BTRFS use folio->private so that they receive a > callback while releasing folios. Add check if folio size is same as > filesystem block size while evaluating iomap_folio_state from > folio->private. > > I am hoping this will be removed when all of btrfs code has moved to > iomap and BTRFS uses iomap's subpage. This seems like a terrible explanation for why you need this patch. As I understand it, what you're really doing is saying that iomap only uses folio->private for block size < folio size. So if you add this hack, iomap won't look at folio->private for block size == folio size and that means that btrfs can continue to use it. I don't think this is a good way to start the conversion. I appreciate that it's a long, complex procedure, and you can't do the whole conversion in a single patchset. Also, please stop calling this "subpage". That's btrfs terminology, it's confusing as hell, and it should be deleted from your brain. But I don't understand why you need it at all. btrfs doesn't attach private data to folios unless block size < page size. Which is precisely the case that you're not using. So it seems like you could just drop this patch and everything would still work.
