On Tue, Sep 13, 2022 at 12:17:06PM +0800, ZiyangZhang wrote: > START_USER_RECOVERY and END_USER_RECOVERY are two new control commands > to support user recovery feature. > > After a crash, user should send START_USER_RECOVERY, it will: > (1) check if (a)current ublk_device is UBLK_S_DEV_QUIESCED which was > set by quiesce_work and (b)the file struct is released. > (2) reinit all ubqs, including: > (a) put the task_struct and reset ->ubq_daemon to NULL. > (b) reset all ublk_io. > (3) reset ub->mm to NULL. > > Then, user should start a new process and send FETCH_REQ on each > ubq_daemon. > > Finally, user should send END_USER_RECOVERY, it will: > (1) wait for all new ubq_daemons getting ready. > (2) update ublksrv_pid > (3) unquiesce the request queue and expect incoming ublk_queue_rq() > (4) convert ub's state to UBLK_S_DEV_LIVE > > Note: we can handle STOP_DEV between START_USER_RECOVERY and > END_USER_RECOVERY. This is helpful to users who cannot start new process > after sending START_USER_RECOVERY ctrl-cmd. > > Signed-off-by: ZiyangZhang <ZiyangZhang@xxxxxxxxxxxxxxxxx> > --- > drivers/block/ublk_drv.c | 116 +++++++++++++++++++++++++++++++++++++++ > 1 file changed, 116 insertions(+) > > diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c > index 4409a130d0b6..3a3af80ee938 100644 > --- a/drivers/block/ublk_drv.c > +++ b/drivers/block/ublk_drv.c > @@ -1961,6 +1961,116 @@ static int ublk_ctrl_set_params(struct io_uring_cmd *cmd) > return ret; > } > > +static void ublk_queue_reinit(struct ublk_device *ub, struct ublk_queue *ubq) > +{ > + int i; > + > + WARN_ON_ONCE(!(ubq->ubq_daemon && ubq_daemon_is_dying(ubq))); > + /* All old ioucmds have to be completed */ > + WARN_ON_ONCE(ubq->nr_io_ready); > + pr_devel("%s: prepare for recovering qid %d\n", __func__, ubq->q_id); > + /* old daemon is PF_EXITING, put it now */ > + put_task_struct(ubq->ubq_daemon); > + /* We have to reset it to NULL, otherwise ub won't accept new FETCH_REQ */ > + ubq->ubq_daemon = NULL; > + > + for (i = 0; i < ubq->q_depth; i++) { > + struct ublk_io *io = &ubq->ios[i]; > + > + /* forget everything now and be ready for new FETCH_REQ */ > + io->flags = 0; > + io->cmd = NULL; > + io->addr = 0; > + } > +} > + > +static int ublk_ctrl_start_recovery(struct io_uring_cmd *cmd) > +{ > + struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd; > + struct ublk_device *ub; > + int ret = -EINVAL; > + int i; > + > + ub = ublk_get_device_from_id(header->dev_id); > + if (!ub) > + return ret; > + > + mutex_lock(&ub->mutex); > + if (!ublk_can_use_recovery(ub)) > + goto out_unlock; > + /* > + * START_RECOVERY is only allowd after: > + * > + * (1) UB_STATE_OPEN is not set, which means the dying process is exited > + * and related io_uring ctx is freed so file struct of /dev/ublkcX is > + * released. > + * > + * (2) UBLK_S_DEV_QUIESCED is set, which means the quiesce_work: > + * (a)has quiesced request queue > + * (b)has requeued every inflight rqs whose io_flags is ACTIVE > + * (c)has requeued/aborted every inflight rqs whose io_flags is NOT ACTIVE > + * (d)has completed/camceled all ioucmds owned by ther dying process > + */ > + if (test_bit(UB_STATE_OPEN, &ub->state) || > + ub->dev_info.state != UBLK_S_DEV_QUIESCED) { > + ret = -EBUSY; > + goto out_unlock; > + } > + pr_devel("%s: start recovery for dev id %d.\n", __func__, header->dev_id); > + for (i = 0; i < ub->dev_info.nr_hw_queues; i++) > + ublk_queue_reinit(ub, ublk_get_queue(ub, i)); > + /* set to NULL, otherwise new ubq_daemon cannot mmap the io_cmd_buf */ > + ub->mm = NULL; > + ub->nr_queues_ready = 0; I am wondering why you don't move the above(queue reinit, clearing ub->mm) into ublk_ch_release(), and looks it is more clean to clear this stuff there. Meantime I guess one control command might be enough for user recovery. Thanks, Ming