On Tue, Jun 20, 2017 at 06:43:10AM -0600, Jens Axboe wrote:

quoted

Question:  IFF we can get the per-file hints to propagate to the
writeback code (which I think is pretty easy for ext4/xfs/bdev, not
sure about btrfs) do we even need the per-inode ones at all?

How is that possible, the file could be long gone by the time
the writeback kicks in?

each time a page/buffer is dirtied we can propagate the hint.