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ublk_drv: add START_USER_RECOVERY and END_USER_RECOVERY support

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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 <ZiyangZhang@linux.alibaba.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20220923153919.44078-7-ZiyangZhang@linux.alibaba.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
ZiyangZhang 2022-09-23 23:39:18 +08:00 committed by Jens Axboe
parent a0d41dc113
commit c732a852b4
2 changed files with 118 additions and 1 deletions
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116
drivers/block/ublk_drv.c
View File

@ -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;
}

3
include/uapi/linux/ublk_cmd.h
View File

@ -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.
*