On Wed, Aug 27, 2025 at 05:20:53PM +0200, Jan Kara wrote: > Now both the old and new behavior make some sense so I won't argue that the > new iomap_iter() behavior is wrong. But I think we should change ext4 back > to the old behavior of failing unaligned dio writes instead of them falling > back to buffered IO. I think something like the attached patch should do > the trick - it makes unaligned dio writes fail again while writes to holes > of indirect-block mapped files still correctly fall back to buffered IO. > Once fstests run completes, I'll do a proper submission... Your suggestion looks all well and good, but I have a general question about fstests. I've written up some to test this series, and I have filesystem specific expectations for what should error or succeed. If you modify ext4 to fail direct-io as described, my test will have to be kernel version specific too. Is there a best practice in fstests for handling such scenarios?
