[libvirt PATCH] qemu: Shorten domain name in virtiofsd log path

[Ján Tomko]

On a Thursday in 2022, Martin Kletzander wrote:
>This helps when starting domains with long names which could possibly end up
>creating too long of a name for the filesystem.
>
>The path is not being saved in the domain config, so there is no need for
>backwards compatibility.  User aliases will always start with "ua-" and the only
>way paths could collide is to:
>
>1) create a domain named e.g. "asdf-ua"
>2) start the domain with virtiofsd debug logs
>3) destroy the domain
>4) restart libvirt daemon for domain IDs to start from 1 again
>5) create a domain named "asdf"
>6) add user alias for the virtiofs that is the same as was generated for the
>   first domain, with the required "ua-" prefix
>7) start the "asdf" domain
>
>at which point the logs for the two domains would end up in the same logfile.

>Since this is still better than what we had before I think it is not worth
>fixing this peculiar scenario in this patch.
>

I don't think this is better. It does fix it for the strange use case
of using very long domain names, and I agree that people combining
domain names with "-ua" suffixes and no user aliases along with
exact same domain names without the -ua suffix, but using user aliases
are not worth worrying about.

But for the 99 % of reasonable users, this patch includes the domain ID
in the log path, so the path can change across restarts of the same domain.
I don't like including this transient identifier in the log path.
We also don't shorten the domain log, since we expect it to stay after
the domain stops running.

Jano

>Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1817401
>Signed-off-by: Martin Kletzander <mkletzan at redhat.com>
>---
> src/qemu/qemu_virtiofs.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
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