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Message-Id: <20220913041707.197334-6-ZiyangZhang@linux.alibaba.com>
Date: Tue, 13 Sep 2022 12:17:05 +0800
From: ZiyangZhang <ZiyangZhang@...ux.alibaba.com>
To: ming.lei@...hat.com
Cc: axboe@...nel.dk, xiaoguang.wang@...ux.alibaba.com,
linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
joseph.qi@...ux.alibaba.com,
ZiyangZhang <ZiyangZhang@...ux.alibaba.com>
Subject: [PATCH V3 5/7] ublk_drv: consider recovery feature in aborting mechanism
With USER_RECOVERY feature enabled, the monitor_work schedules
quiesce_work after finding a dying ubq_daemon. The quiesce_work's job
is to:
(1) quiesce request queue.
(2) check if there is any INFLIGHT rq with UBLK_IO_FLAG_ACTIVE unset.
If so, we retry until all these rqs are requeued by ublk_queue_rq()
and task_work and become IDLE.
(3) requeue/abort inflight rqs issued to the crash ubq_daemon before. If
UBLK_F_USER_RECOVERY_REISSUE is set, rq is requeued; or it is
aborted.
(4) complete all ioucmds by calling io_uring_cmd_done(). We are safe to
do so because no ioucmd can be referenced now.
(5) set ub's state to UBLK_S_DEV_QUIESCED, which means we are ready for
recovery. This state is exposed to userspace by GET_DEV_INFO.
The driver can always handle STOP_DEV and cleanup everything no matter
ub's state is LIVE or QUIESCED. After ub's state is UBLK_S_DEV_QUIESCED,
user can recover with new process by sending START_USER_RECOVERY.
Note: we do not change the default behavior with reocvery feature
disabled. monitor_work still schedules stop_work and abort inflight
rqs. Finally ublk_device is released.
Signed-off-by: ZiyangZhang <ZiyangZhang@...ux.alibaba.com>
---
drivers/block/ublk_drv.c | 168 +++++++++++++++++++++++++++++++++++++--
1 file changed, 161 insertions(+), 7 deletions(-)
diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index b067f33a1913..4409a130d0b6 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -121,7 +121,7 @@ struct ublk_queue {
unsigned long io_addr; /* mapped vm address */
unsigned int max_io_sz;
- bool abort_work_pending;
+ bool force_abort;
unsigned short nr_io_ready; /* how many ios setup */
struct ublk_device *dev;
struct ublk_io ios[0];
@@ -163,6 +163,7 @@ struct ublk_device {
* monitor each queue's daemon periodically
*/
struct delayed_work monitor_work;
+ struct work_struct quiesce_work;
struct work_struct stop_work;
};
@@ -660,6 +661,11 @@ static void __ublk_fail_req(struct ublk_io *io, struct request *req)
WARN_ON_ONCE(io->flags & UBLK_IO_FLAG_ACTIVE);
if (!(io->flags & UBLK_IO_FLAG_ABORTED)) {
+ pr_devel("%s: abort rq: qid %d tag %d io_flags %x\n",
+ __func__,
+ ((struct ublk_queue *)req->mq_hctx->driver_data)->q_id,
+ req->tag,
+ io->flags);
io->flags |= UBLK_IO_FLAG_ABORTED;
blk_mq_end_request(req, BLK_STS_IOERR);
}
@@ -820,6 +826,21 @@ static blk_status_t ublk_queue_rq(struct blk_mq_hw_ctx *hctx,
res = ublk_setup_iod(ubq, rq);
if (unlikely(res != BLK_STS_OK))
return BLK_STS_IOERR;
+ /* With recovery feature enabled, force_abort is set in
+ * ublk_stop_dev() before calling del_gendisk() if ub's state
+ * is QUIESCED. We have to abort all requeued and new rqs here
+ * to let del_gendisk() move on. Besides, we do not call
+ * io_uring_cmd_complete_in_task() to avoid UAF on io_uring ctx.
+ *
+ * Note: force_abort is guaranteed to be seen because it is set
+ * before request queue is unqiuesced.
+ */
+ if (unlikely(ubq->force_abort)) {
+ pr_devel("%s: abort rq: qid %d tag %d io_flags %x\n",
+ __func__, ubq->q_id, rq->tag,
+ ubq->ios[rq->tag].flags);
+ return BLK_STS_IOERR;
+ }
blk_mq_start_request(bd->rq);
@@ -1003,6 +1024,101 @@ static void ublk_abort_queue(struct ublk_device *ub, struct ublk_queue *ubq)
ublk_put_device(ub);
}
+static bool ublk_check_inflight_rq(struct request *rq, void *data)
+{
+ struct ublk_queue *ubq = rq->mq_hctx->driver_data;
+ struct ublk_io *io = &ubq->ios[rq->tag];
+ bool *busy = data;
+
+ if (io->flags & UBLK_IO_FLAG_ACTIVE) {
+ *busy = true;
+ return false;
+ }
+ return true;
+}
+
+static void ublk_wait_tagset_rqs_idle(struct ublk_device *ub)
+{
+ bool busy = false;
+
+ WARN_ON_ONCE(!blk_queue_quiesced(ub->ub_disk->queue));
+ while (true) {
+ blk_mq_tagset_busy_iter(&ub->tag_set,
+ ublk_check_inflight_rq, &busy);
+ if (busy)
+ msleep(UBLK_REQUEUE_DELAY_MS);
+ else
+ break;
+ }
+}
+
+static void ublk_quiesce_queue(struct ublk_device *ub,
+ struct ublk_queue *ubq)
+{
+ int i;
+
+ for (i = 0; i < ubq->q_depth; i++) {
+ struct ublk_io *io = &ubq->ios[i];
+
+ if (!(io->flags & UBLK_IO_FLAG_ACTIVE)) {
+ struct request *rq = blk_mq_tag_to_rq(
+ ub->tag_set.tags[ubq->q_id], i);
+
+ WARN_ON_ONCE(!rq);
+ pr_devel("%s: %s rq: qid %d tag %d io_flags %x\n", __func__,
+ ublk_queue_can_use_recovery_reissue(ubq) ?
+ "requeue" : "abort",
+ ubq->q_id, i, io->flags);
+ if (ublk_queue_can_use_recovery_reissue(ubq))
+ blk_mq_requeue_request(rq, false);
+ else
+ __ublk_fail_req(io, rq);
+ } else {
+ pr_devel("%s: done old cmd: qid %d tag %d\n",
+ __func__, ubq->q_id, i);
+ io_uring_cmd_done(io->cmd, UBLK_IO_RES_ABORT, 0);
+ io->flags &= ~UBLK_IO_FLAG_ACTIVE;
+ }
+ ubq->nr_io_ready--;
+ }
+ WARN_ON_ONCE(ubq->nr_io_ready);
+}
+
+static void ublk_quiesce_dev(struct ublk_device *ub)
+{
+ int i;
+
+ mutex_lock(&ub->mutex);
+ if (ub->dev_info.state != UBLK_S_DEV_LIVE)
+ goto unlock;
+
+ for (i = 0; i < ub->dev_info.nr_hw_queues; i++) {
+ struct ublk_queue *ubq = ublk_get_queue(ub, i);
+
+ if (!ubq_daemon_is_dying(ubq))
+ goto unlock;
+ }
+ blk_mq_quiesce_queue(ub->ub_disk->queue);
+ ublk_wait_tagset_rqs_idle(ub);
+ pr_devel("%s: quiesce ub: dev_id %d\n",
+ __func__, ub->dev_info.dev_id);
+
+ for (i = 0; i < ub->dev_info.nr_hw_queues; i++)
+ ublk_quiesce_queue(ub, ublk_get_queue(ub, i));
+
+ ub->dev_info.state = UBLK_S_DEV_QUIESCED;
+ unlock:
+ mutex_unlock(&ub->mutex);
+}
+
+static void ublk_quiesce_work_fn(struct work_struct *work)
+{
+ struct ublk_device *ub =
+ container_of(work, struct ublk_device, quiesce_work);
+
+ ublk_quiesce_dev(ub);
+}
+
static void ublk_daemon_monitor_work(struct work_struct *work)
{
struct ublk_device *ub =
@@ -1013,10 +1129,14 @@ static void ublk_daemon_monitor_work(struct work_struct *work)
struct ublk_queue *ubq = ublk_get_queue(ub, i);
if (ubq_daemon_is_dying(ubq)) {
- schedule_work(&ub->stop_work);
-
- /* abort queue is for making forward progress */
- ublk_abort_queue(ub, ubq);
+ if (ublk_queue_can_use_recovery(ubq)) {
+ schedule_work(&ub->quiesce_work);
+ } else {
+ schedule_work(&ub->stop_work);
+
+ /* abort queue is for making forward progress */
+ ublk_abort_queue(ub, ubq);
+ }
}
}
@@ -1080,12 +1200,43 @@ static void ublk_cancel_dev(struct ublk_device *ub)
ublk_cancel_queue(ublk_get_queue(ub, i));
}
+static void ublk_unquiesce_dev(struct ublk_device *ub)
+{
+ int i;
+
+ pr_devel("%s: ub state %s\n", __func__,
+ ub->dev_info.state == UBLK_S_DEV_LIVE ?
+ "LIVE" : "QUIESCED");
+ if (ub->dev_info.state == UBLK_S_DEV_LIVE) {
+ /*
+ * quiesce_work cannot be running. We let monitor_work,
+ * ublk_queue_rq() and task_work abort rqs instead of
+ * requeuing them with a dying ubq_daemon. Then
+ * del_gendisk() can move on.
+ */
+ ublk_disable_recovery(ub);
+ } else {
+ /* quiesce_work has run. We let requeued rqs be aborted
+ * before running fallback_wq. "force_abort" must be seen
+ * after request queue is unqiuesced. Then del_gendisk()
+ * can move on.
+ */
+ for (i = 0; i < ub->dev_info.nr_hw_queues; i++)
+ ublk_get_queue(ub, i)->force_abort = true;
+
+ blk_mq_unquiesce_queue(ub->ub_disk->queue);
+ /* We may have requeued some rqs in ublk_quiesce_queue() */
+ blk_mq_kick_requeue_list(ub->ub_disk->queue);
+ }
+}
+
static void ublk_stop_dev(struct ublk_device *ub)
{
mutex_lock(&ub->mutex);
- if (ub->dev_info.state != UBLK_S_DEV_LIVE)
+ if (ub->dev_info.state == UBLK_S_DEV_DEAD)
goto unlock;
-
+ if (ublk_can_use_recovery(ub))
+ ublk_unquiesce_dev(ub);
del_gendisk(ub->ub_disk);
ub->dev_info.state = UBLK_S_DEV_DEAD;
ub->dev_info.ublksrv_pid = -1;
@@ -1409,6 +1560,7 @@ static void ublk_remove(struct ublk_device *ub)
{
ublk_stop_dev(ub);
cancel_work_sync(&ub->stop_work);
+ cancel_work_sync(&ub->quiesce_work);
cdev_device_del(&ub->cdev, &ub->cdev_dev);
put_device(&ub->cdev_dev);
}
@@ -1585,6 +1737,7 @@ static int ublk_ctrl_add_dev(struct io_uring_cmd *cmd)
goto out_unlock;
mutex_init(&ub->mutex);
spin_lock_init(&ub->mm_lock);
+ INIT_WORK(&ub->quiesce_work, ublk_quiesce_work_fn);
INIT_WORK(&ub->stop_work, ublk_stop_work_fn);
INIT_DELAYED_WORK(&ub->monitor_work, ublk_daemon_monitor_work);
@@ -1705,6 +1858,7 @@ static int ublk_ctrl_stop_dev(struct io_uring_cmd *cmd)
ublk_stop_dev(ub);
cancel_work_sync(&ub->stop_work);
+ cancel_work_sync(&ub->quiesce_work);
ublk_put_device(ub);
return 0;
--
2.27.0
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