[rwmj]

Direct IO is very inflexible. A better way is this recommended by Linus in an old post:

https://lkml.iu.edu/hypermail/linux/kernel/1005.2/01845.html

I implemented something along the same lines but a bit less spicy here:

https://gitlab.com/nbdkit/nbdkit/-/commit/aa5a2183a6d16afd91...

[rwmj]

That second link is wrong, should be: https://gitlab.com/nbdkit/nbdkit/-/commit/a956e2e75d6c88eeef...