ublk currently supports the following behaviors on ublk server exit:
A: outstanding I/Os get errors, subsequently issued I/Os get errors
B: outstanding I/Os get errors, subsequently issued I/Os queue
C: outstanding I/Os get reissued, subsequently issued I/Os queue
and the following behaviors for recovery of preexisting block devices by
a future incarnation of the ublk server:
1: ublk devices stopped on ublk server exit (no recovery possible)
2: ublk devices are recoverable using start/end_recovery commands
The userspace interface allows selection of combinations of these
behaviors using flags specified at device creation time, namely:
default behavior: A + 1
UBLK_F_USER_RECOVERY: B + 2
UBLK_F_USER_RECOVERY|UBLK_F_USER_RECOVERY_REISSUE: C + 2
We can't easily change the userspace interface to allow independent
selection of one of {A, B, C} and one of {1, 2}, but we can refactor the
internal helpers which test for the flags. Replace the existing helpers
with the following set:
ublk_nosrv_should_reissue_outstanding: tests for behavior C
ublk_nosrv_[dev_]should_queue_io: tests for behavior B
ublk_nosrv_should_stop_dev: tests for behavior 1
Signed-off-by: Uday Shankar <ushankar@xxxxxxxxxxxxxxx>
---
Changes since v1 (https://lore.kernel.org/linux-block/20240617194451.435445-3-ushankar@xxxxxxxxxxxxxxx/):
- Make the fast-path test in ublk_queue_rq access the queue-local copy
of the device flags.
drivers/block/ublk_drv.c | 63 +++++++++++++++++++++++++++-------------
1 file changed, 43 insertions(+), 20 deletions(-)
diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 5e04a0fcd0b7..b069f4d2b9d2 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -675,22 +675,45 @@ static inline int ublk_queue_cmd_buf_size(struct ublk_device *ub, int q_id)
PAGE_SIZE);
}
-static inline bool ublk_queue_can_use_recovery_reissue(
- struct ublk_queue *ubq)
+/*
+ * Should I/O outstanding to the ublk server when it exits be reissued?
+ * If not, outstanding I/O will get errors.
+ */
+static inline bool ublk_nosrv_should_reissue_outstanding(struct ublk_device *ub)
{
- return (ubq->flags & UBLK_F_USER_RECOVERY) &&
- (ubq->flags & UBLK_F_USER_RECOVERY_REISSUE);
+ return (ub->dev_info.flags & UBLK_F_USER_RECOVERY) &&
+ (ub->dev_info.flags & UBLK_F_USER_RECOVERY_REISSUE);
}
-static inline bool ublk_queue_can_use_recovery(
- struct ublk_queue *ubq)
+/*
+ * Should I/O issued while there is no ublk server queue? If not, I/O
+ * issued while there is no ublk server will get errors.
+ */
+static inline bool ublk_nosrv_dev_should_queue_io(struct ublk_device *ub)
+{
+ return ub->dev_info.flags & UBLK_F_USER_RECOVERY;
+}
+
+/*
+ * Same as ublk_nosrv_dev_should_queue_io, but uses a queue-local copy
+ * of the device flags for smaller cache footprint - better for fast
+ * paths.
+ */
+static inline bool ublk_nosrv_should_queue_io(struct ublk_queue *ubq)
{
return ubq->flags & UBLK_F_USER_RECOVERY;
}
-static inline bool ublk_can_use_recovery(struct ublk_device *ub)
+/*
+ * Should ublk devices be stopped (i.e. no recovery possible) when the
+ * ublk server exits? If not, devices can be used again by a future
+ * incarnation of a ublk server via the start_recovery/end_recovery
+ * commands.
+ */
+static inline bool ublk_nosrv_should_stop_dev(struct ublk_device *ub)
{
- return ub->dev_info.flags & UBLK_F_USER_RECOVERY;
+ return (!(ub->dev_info.flags & UBLK_F_USER_RECOVERY)) &&
+ (!(ub->dev_info.flags & UBLK_F_USER_RECOVERY_REISSUE));
}
static void ublk_free_disk(struct gendisk *disk)
@@ -1066,7 +1089,7 @@ static void __ublk_fail_req(struct ublk_queue *ubq, struct ublk_io *io,
{
WARN_ON_ONCE(io->flags & UBLK_IO_FLAG_ACTIVE);
- if (ublk_queue_can_use_recovery_reissue(ubq))
+ if (ublk_nosrv_should_reissue_outstanding(ubq->dev))
blk_mq_requeue_request(req, false);
else
ublk_put_req_ref(ubq, req);
@@ -1094,7 +1117,7 @@ static inline void __ublk_abort_rq(struct ublk_queue *ubq,
struct request *rq)
{
/* We cannot process this rq so just requeue it. */
- if (ublk_queue_can_use_recovery(ubq))
+ if (ublk_nosrv_dev_should_queue_io(ubq->dev))
blk_mq_requeue_request(rq, false);
else
blk_mq_end_request(rq, BLK_STS_IOERR);
@@ -1239,10 +1262,10 @@ static enum blk_eh_timer_return ublk_timeout(struct request *rq)
struct ublk_device *ub = ubq->dev;
if (ublk_abort_requests(ub, ubq)) {
- if (ublk_can_use_recovery(ub))
- schedule_work(&ub->quiesce_work);
- else
+ if (ublk_nosrv_should_stop_dev(ub))
schedule_work(&ub->stop_work);
+ else
+ schedule_work(&ub->quiesce_work);
}
return BLK_EH_DONE;
}
@@ -1271,7 +1294,7 @@ static blk_status_t ublk_queue_rq(struct blk_mq_hw_ctx *hctx,
* Note: force_abort is guaranteed to be seen because it is set
* before request queue is unqiuesced.
*/
- if (ublk_queue_can_use_recovery(ubq) && unlikely(ubq->force_abort))
+ if (ublk_nosrv_should_queue_io(ubq) && unlikely(ubq->force_abort))
return BLK_STS_IOERR;
if (unlikely(ubq->canceling)) {
@@ -1492,10 +1515,10 @@ static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd,
ublk_cancel_cmd(ubq, io, issue_flags);
if (need_schedule) {
- if (ublk_can_use_recovery(ub))
- schedule_work(&ub->quiesce_work);
- else
+ if (ublk_nosrv_should_stop_dev(ub))
schedule_work(&ub->stop_work);
+ else
+ schedule_work(&ub->quiesce_work);
}
}
@@ -1600,7 +1623,7 @@ static void ublk_stop_dev(struct ublk_device *ub)
mutex_lock(&ub->mutex);
if (ub->dev_info.state == UBLK_S_DEV_DEAD)
goto unlock;
- if (ublk_can_use_recovery(ub)) {
+ if (ublk_nosrv_dev_should_queue_io(ub)) {
if (ub->dev_info.state == UBLK_S_DEV_LIVE)
__ublk_quiesce_dev(ub);
ublk_unquiesce_dev(ub);
@@ -2702,7 +2725,7 @@ static int ublk_ctrl_start_recovery(struct ublk_device *ub,
int i;
mutex_lock(&ub->mutex);
- if (!ublk_can_use_recovery(ub))
+ if (ublk_nosrv_should_stop_dev(ub))
goto out_unlock;
if (!ub->nr_queues_ready)
goto out_unlock;
@@ -2755,7 +2778,7 @@ static int ublk_ctrl_end_recovery(struct ublk_device *ub,
__func__, ub->dev_info.nr_hw_queues, header->dev_id);
mutex_lock(&ub->mutex);
- if (!ublk_can_use_recovery(ub))
+ if (ublk_nosrv_should_stop_dev(ub))
goto out_unlock;
if (ub->dev_info.state != UBLK_S_DEV_QUIESCED) {
--
2.34.1
