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authorJens Axboe <axboe@fb.com>2017-04-10 09:54:56 -0600
committerJens Axboe <axboe@fb.com>2017-04-28 08:11:43 -0600
commit21c6e939a9f6bb06fe616a87defec0f92a7c3df0 (patch)
tree4313793669d17a93b634236023d5ad3cf1c5ee22 /block
parent818cd1cbaa7b00bbc35452a76bebc681a65f1912 (diff)
downloadblackbird-obmc-linux-21c6e939a9f6bb06fe616a87defec0f92a7c3df0.tar.gz
blackbird-obmc-linux-21c6e939a9f6bb06fe616a87defec0f92a7c3df0.zip
blk-mq: unify hctx delay_work and run_work
The only difference between ->run_work and ->delay_work, is that the latter is used to defer running a queue. This is done by marking the queue stopped, and scheduling ->delay_work to run sometime in the future. While the queue is stopped, direct runs or runs through ->run_work will not run the queue. If we combine the handlers, then we need to handle two things: 1) If a delayed/stopped run is scheduled, then we should not run the queue before that has been completed. 2) If a queue is delayed/stopped, the handler needs to restart the queue. Normally a run of a queue with the stopped bit set would be a no-op. Case 1 is handled by modifying a currently pending queue run to the deadline set by the caller of blk_mq_delay_queue(). Subsequent attempts to queue a queue run will find the work item already pending, and direct runs will see a stopped queue as before. Case 2 is handled by adding a new bit, BLK_MQ_S_START_ON_RUN, that tells the work handler that it should clear a stopped queue and run the handler. Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block')
-rw-r--r--block/blk-core.c4
-rw-r--r--block/blk-mq.c34
2 files changed, 23 insertions, 15 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index 64b6e58532bf..24886b69690f 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -268,10 +268,8 @@ void blk_sync_queue(struct request_queue *q)
struct blk_mq_hw_ctx *hctx;
int i;
- queue_for_each_hw_ctx(q, hctx, i) {
+ queue_for_each_hw_ctx(q, hctx, i)
cancel_delayed_work_sync(&hctx->run_work);
- cancel_delayed_work_sync(&hctx->delay_work);
- }
} else {
cancel_delayed_work_sync(&q->delay_work);
}
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 5c68fce87ffc..a0bdf63aebfe 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1221,7 +1221,6 @@ EXPORT_SYMBOL(blk_mq_queue_stopped);
void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
{
cancel_delayed_work_sync(&hctx->run_work);
- cancel_delayed_work(&hctx->delay_work);
set_bit(BLK_MQ_S_STOPPED, &hctx->state);
}
EXPORT_SYMBOL(blk_mq_stop_hw_queue);
@@ -1279,27 +1278,39 @@ static void blk_mq_run_work_fn(struct work_struct *work)
struct blk_mq_hw_ctx *hctx;
hctx = container_of(work, struct blk_mq_hw_ctx, run_work.work);
- __blk_mq_run_hw_queue(hctx);
-}
-static void blk_mq_delay_work_fn(struct work_struct *work)
-{
- struct blk_mq_hw_ctx *hctx;
+ /*
+ * If we are stopped, don't run the queue. The exception is if
+ * BLK_MQ_S_START_ON_RUN is set. For that case, we auto-clear
+ * the STOPPED bit and run it.
+ */
+ if (test_bit(BLK_MQ_S_STOPPED, &hctx->state)) {
+ if (!test_bit(BLK_MQ_S_START_ON_RUN, &hctx->state))
+ return;
- hctx = container_of(work, struct blk_mq_hw_ctx, delay_work.work);
+ clear_bit(BLK_MQ_S_START_ON_RUN, &hctx->state);
+ clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
+ }
- if (test_and_clear_bit(BLK_MQ_S_STOPPED, &hctx->state))
- __blk_mq_run_hw_queue(hctx);
+ __blk_mq_run_hw_queue(hctx);
}
+
void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
{
if (unlikely(!blk_mq_hw_queue_mapped(hctx)))
return;
+ /*
+ * Stop the hw queue, then modify currently delayed work.
+ * This should prevent us from running the queue prematurely.
+ * Mark the queue as auto-clearing STOPPED when it runs.
+ */
blk_mq_stop_hw_queue(hctx);
- kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
- &hctx->delay_work, msecs_to_jiffies(msecs));
+ set_bit(BLK_MQ_S_START_ON_RUN, &hctx->state);
+ kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
+ &hctx->run_work,
+ msecs_to_jiffies(msecs));
}
EXPORT_SYMBOL(blk_mq_delay_queue);
@@ -1885,7 +1896,6 @@ static int blk_mq_init_hctx(struct request_queue *q,
node = hctx->numa_node = set->numa_node;
INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn);
- INIT_DELAYED_WORK(&hctx->delay_work, blk_mq_delay_work_fn);
spin_lock_init(&hctx->lock);
INIT_LIST_HEAD(&hctx->dispatch);
hctx->queue = q;
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