On 05/27/2019 01:23 PM, Yao Liu wrote: > On Fri, May 24, 2019 at 09:08:58AM -0400, Josef Bacik wrote: >> On Fri, May 24, 2019 at 05:43:55PM +0800, Yao Liu wrote: >>> Some nbd client implementations have a userland's daemon, so we should >>> inform client daemon to clean up and exit. >>> >>> Signed-off-by: Yao Liu <yotta.liu@xxxxxxxxx> >> >> Except the nbd_disconnected() check is for the case that the client told us >> specifically to disconnect, so we don't want to send the notification to >> re-connect because we've already been told we want to tear everything down. >> Nack to this as well. Thanks, >> >> Josef >> > > But in userland, client daemon process and process which send disconnect > command are not same process, so they are not clear to each other, so > client daemon expect driver inform it to exit. > In addition, client daemon will get nbd status with nbd_genl_status interface > after it get notified and it should not re-connect if status connected == 0 > When using the netlink interface you get the NBD_CMD_LINK_DEAD first then the configs_refs goes to zero right? nbd_disconnect_and_put -> sock_shutdown -> nbd_mark_nsock_dead then later we do the final nbd_config_put? Maybe it would be best to add a new netlink event to signal what has happened, because the above nl and stat algorithm seems like a pain. The NBD_CMD_LINK_DEAD will be sent, then userspace has to possibly poll the status to check if this was caused due to nbd_genl_disconnect instead of a downed link due to something like a command timeout, because the refcount may not be down when userspace gets the NL event. Or, I guess the admin/tool process could just send a msg to the daemon process to tell it to do the netlink disconnect request.
