Re: [PATCH RFC] gen_init_cpio: Do fsync() only on regular files

[Christoph Hellwig]

On Tue, Oct 07, 2025 at 12:55:03AM +0100, Dmitry Safonov via B4 Relay wrote:
> From: Dmitry Safonov <dima@xxxxxxxxxx>
> 
> Here at Arista gen_init_cpio is used in testing in order to create
> an initramfs for specific tests. Most notably, there is a test that does
> essentially a fork-bomb in kdump/panic kernel, replacing build-time
> generated init script: instead of doing makedumpfile, it does call
> shell tests.

Why is is using fsync at all?  Seems like this was added in

commit ae18b94099b04264b32e33b057114024bc72c993
Author: David Disseldorp <ddiss@xxxxxxx>
Date:   Tue Aug 19 13:05:45 2025 +1000

    gen_init_cpio: support -o <output_file> parameter

without any good explanation.  In general doing a per-file fsync
is going to horrible wreck performance, and given that no one is
interested in partial initramfs archives also rather pointless.