Re: How does NetBSD handle fsync() that incurs I/O errors?

[Sad Clouds <cryintothebluesky%gmail.com@localhost>]

On Fri, 30 Mar 2018 15:12:31 +0200
Rhialto <rhialto%falu.nl@localhost> wrote:

> I have just been pointed at a postgresql mailing list discussion
> about a scenario where a program has written data to a file
> descriptor, calls fsync(), there is an I/O error in writing the data
> out, and the program re-tries the fsync() until it returns success.

Hello, I don't know how NetBSD kernel handles this, but I think this
program's design may be flawed. When writing to a single file, any I/O
error means some data didn't make it, but which data and how much of
it, is really up to the implementation. Not sure it is safe to assume
anything at this point.

A better design would be to write some data, call fsync, and if any
errors occur, then retry I/O, rather than just fsync. This is more
complicated with small random I/O.