From c732a852b419fa057b53657e2daaf9433940391c Mon Sep 17 00:00:00 2001 From: ZiyangZhang Date: Fri, 23 Sep 2022 23:39:18 +0800 Subject: [PATCH] ublk_drv: add START_USER_RECOVERY and END_USER_RECOVERY support 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)chardev 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 Reviewed-by: Ming Lei Link: https://lore.kernel.org/r/20220923153919.44078-7-ZiyangZhang@linux.alibaba.com Signed-off-by: Jens Axboe --- drivers/block/ublk_drv.c | 116 ++++++++++++++++++++++++++++++++++++++++++ include/uapi/linux/ublk_cmd.h | 3 +- 2 files changed, 118 insertions(+), 1 deletion(-) diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index 76ee41e..2651bf4 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -1861,6 +1861,116 @@ 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); + /* 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; + schedule_delayed_work(&ub->monitor_work, UBLK_DAEMON_MONITOR_PERIOD); + 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) { @@ -1902,6 +2012,12 @@ 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; } diff --git a/include/uapi/linux/ublk_cmd.h b/include/uapi/linux/ublk_cmd.h index 3323706..8f88e3a 100644 --- a/include/uapi/linux/ublk_cmd.h +++ b/include/uapi/linux/ublk_cmd.h @@ -17,7 +17,8 @@ #define UBLK_CMD_STOP_DEV 0x07 #define UBLK_CMD_SET_PARAMS 0x08 #define UBLK_CMD_GET_PARAMS 0x09 - +#define UBLK_CMD_START_USER_RECOVERY 0x10 +#define UBLK_CMD_END_USER_RECOVERY 0x11 /* * IO commands, issued by ublk server, and handled by ublk driver. * -- 2.7.4