On Mon, Feb 08, 2021 at 07:30:08PM -0700, Jens Axboe wrote:
> + if (iocb->ki_flags & IOCB_NOWAIT) {
> + if (filemap_range_needs_writeback(mapping, pos, end)) {
> + ret = -EAGAIN;
> + goto out_free_dio;
> + }
> + flags |= IOMAP_NOWAIT;
> + }
> if (iter_is_iovec(iter))
> dio->flags |= IOMAP_DIO_DIRTY;
> } else {
> + if (iocb->ki_flags & IOCB_NOWAIT) {
> + if (filemap_range_has_page(mapping, pos, end)) {
> + ret = -EAGAIN;
> + goto out_free_dio;
> + }
> + flags |= IOMAP_NOWAIT;
> + }
> +
> flags |= IOMAP_WRITE;
> dio->flags |= IOMAP_DIO_WRITE;
>
> @@ -478,14 +493,6 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
> dio->flags |= IOMAP_DIO_WRITE_FUA;
> }
>
> - if (iocb->ki_flags & IOCB_NOWAIT) {
> - if (filemap_range_has_page(mapping, pos, end)) {
> - ret = -EAGAIN;
> - goto out_free_dio;
> - }
> - flags |= IOMAP_NOWAIT;
> - }
looking at this I really hate the scheme with the potential racyness
and duplicated page looksups.
Why can't we pass a nonblock flag to filemap_write_and_wait_range
and invalidate_inode_pages2_range that makes them return -EAGAIN
when they would block to clean this whole mess up?
