On Fri, Nov 15, 2024 at 01:55:53PM -0600, Eric Blake wrote: > While testing the use of qemu-nbd in a Pod of a Kubernetes cluster, I > got LOTS of log messages of the forms: > > qemu-nbd: option negotiation failed: Failed to read flags: Unexpected > end-of-file before all data were read > qemu-nbd: option negotiation failed: Failed to read flags: Unable to read > from socket: Connection reset by peer > > While it is nice to warn about clients that aren't following protocol > (in case it helps diagnosing bugs in those clients), a mere port probe > (where the client never write()s any bytes, and where we might even > hit EPIPE in trying to send our greeting to the client) is NOT > abnormal, but merely serves to pollute the log. And Kubernetes > _really_ likes to do port probes to determine whether a given Pod is > up and running. > > Easy ways to demonstrate the above port probes: > $ qemu-nbd -r -f raw path/to/file & > $ nc localhost 10809 </dev/null > $ bash -c 'exec </dev/tcp/localhost/10809' > $ kill $! > > Silence the noise by not capturing errors until after our first > successful read() from a client. > > Signed-off-by: Eric Blake <ebl...@redhat.com> > --- > nbd/server.c | 26 +++++++++++++++++--------- > 1 file changed, 17 insertions(+), 9 deletions(-)
In testing this as a potential candidate for -rc1, I'm seeing iotests failures in `./check 094 119 -nbd` both pre- and post-patch. Bisecting now to see if I can find where those tests started regressing (looks like a timing change; a "return" line is swapping place with a SHUTDOWN event line in the QMP output). -- Eric Blake, Principal Software Engineer Red Hat, Inc. Virtualization: qemu.org | libguestfs.org
