Il 23/05/2013 23:58, Mark Trumpold ha scritto:
> I have a working configuration using the signal approach suggested by Stefan.
>
> 'qemu-nbd.c' is patched as follows:
>
> do {
> main_loop_wait(false);
> + if (sighup_reported) {
> + sighup_reported = false;
> + bdrv_drain_all();
> + bdrv_flush_all();
> }
> } while (!sigterm_reported && (persistent || !nbd_started || nb_fds > 0));
>
> The driving script was patched as follows:
Yes, a patch along these lines would be acceptable.
> mount -o remount,ro /dev/nbd0
> blockdev --flushbufs /dev/nbd0
> + kill -HUP <qemu-nbd process id>
>
> I needed to retain 'blockdev --flushbufs' for things to work. Seems
> the 'bdrv_flush_all' is flushing what is being missed by the blockdev
> flush. I did not go back an retest with 'fsync' or other approaches I
> had tried before.
Right. That said, I think a newer kernel would do what you want.
Perhaps you can look at the actual patches that went into 3.9 and
backport them.
Paolo
