| Message ID | 20220913041707.197334-7-ZiyangZhang@linux.alibaba.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | ublk_drv: add USER_RECOVERY support | expand |
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@linux.alibaba.com> > --- > 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
On 2022/9/19 21:03, Ming Lei wrote: > 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@linux.alibaba.com> >> --- >> 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. OK, START_USER_RECOVERY just does cleanup stuff for a new process and ublk_ch_release() does the similar thing since it is always called when chardev is released. And our new process must open the chardev after it is released. So (queue reinit, clearing ub->mm) can be done in ublk_ch_release(). Regards, Zhang.
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; + init_completion(&ub->completion); + ret = 0; + out_unlock: + mutex_unlock(&ub->mutex); + ublk_put_device(ub); + return ret; +} + +static int ublk_ctrl_end_recovery(struct io_uring_cmd *cmd) +{ + struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd; + int ublksrv_pid = (int)header->data[0]; + struct ublk_device *ub; + int ret = -EINVAL; + + ub = ublk_get_device_from_id(header->dev_id); + if (!ub) + return ret; + + pr_devel("%s: Waiting for new ubq_daemons(nr: %d) are ready, dev id %d...\n", + __func__, ub->dev_info.nr_hw_queues, header->dev_id); + /* wait until new ubq_daemon sending all FETCH_REQ */ + wait_for_completion_interruptible(&ub->completion); + pr_devel("%s: All new ubq_daemons(nr: %d) are ready, dev id %d\n", + __func__, ub->dev_info.nr_hw_queues, header->dev_id); + + mutex_lock(&ub->mutex); + if (!ublk_can_use_recovery(ub)) + goto out_unlock; + + if (ub->dev_info.state != UBLK_S_DEV_QUIESCED) { + ret = -EBUSY; + goto out_unlock; + } + ub->dev_info.ublksrv_pid = ublksrv_pid; + pr_devel("%s: new ublksrv_pid %d, dev id %d\n", + __func__, ublksrv_pid, header->dev_id); + blk_mq_unquiesce_queue(ub->ub_disk->queue); + pr_devel("%s: queue unquiesced, dev id %d.\n", + __func__, header->dev_id); + blk_mq_kick_requeue_list(ub->ub_disk->queue); + ub->dev_info.state = UBLK_S_DEV_LIVE; + ret = 0; + out_unlock: + mutex_unlock(&ub->mutex); + ublk_put_device(ub); + return ret; +} + static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags) { @@ -2002,6 +2112,12 @@ static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd, case UBLK_CMD_SET_PARAMS: ret = ublk_ctrl_set_params(cmd); break; + case UBLK_CMD_START_USER_RECOVERY: + ret = ublk_ctrl_start_recovery(cmd); + break; + case UBLK_CMD_END_USER_RECOVERY: + ret = ublk_ctrl_end_recovery(cmd); + break; default: break; }
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@linux.alibaba.com> --- drivers/block/ublk_drv.c | 116 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 116 insertions(+)