On 7/2/20 3:48 PM, Ming Lei wrote:
The built-in flush request shares tag with the request inserted to flush
machinery, turns out its .end_io callback has to touch the built-in
flush request's internal tag or tag.
On the other hand, we have to make sure that driver tag is released
from __blk_mq_end_request(), since this request may not be completed
via blk_mq_complete_request().
Given we have moved blk_mq_put_driver_tag() out of header file, fix this
issue by releasing driver tag before calling .end_io().
Cc: Christoph Hellwig <hch@xxxxxx>
Reported-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Tested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Fixes: 36a3df5a4574("blk-mq: put driver tag when this request is completed")
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
block/blk-mq.c | 46 ++++++++++++++++++++++++----------------------
1 file changed, 24 insertions(+), 22 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 948987e9b6ab..6b36969220c1 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -532,6 +532,26 @@ void blk_mq_free_request(struct request *rq)
}
EXPORT_SYMBOL_GPL(blk_mq_free_request);
+static void __blk_mq_put_driver_tag(struct blk_mq_hw_ctx *hctx,
+ struct request *rq)
+{
+ blk_mq_put_tag(hctx->tags, rq->mq_ctx, rq->tag);
+ rq->tag = BLK_MQ_NO_TAG;
+
+ if (rq->rq_flags & RQF_MQ_INFLIGHT) {
+ rq->rq_flags &= ~RQF_MQ_INFLIGHT;
+ atomic_dec(&hctx->nr_active);
+ }
+}
+
+static inline void blk_mq_put_driver_tag(struct request *rq)
+{
+ if (rq->tag == BLK_MQ_NO_TAG || rq->internal_tag == BLK_MQ_NO_TAG)
+ return;
+
+ __blk_mq_put_driver_tag(rq->mq_hctx, rq);
+}
+
inline void __blk_mq_end_request(struct request *rq, blk_status_t error)
{
u64 now = 0;
@@ -551,6 +571,7 @@ inline void __blk_mq_end_request(struct request *rq, blk_status_t error)
if (rq->end_io) {
rq_qos_done(rq->q, rq);
+ blk_mq_put_driver_tag(rq);
rq->end_io(rq, error);
} else {
blk_mq_free_request(rq);
@@ -660,26 +681,6 @@ static inline bool blk_mq_complete_need_ipi(struct request *rq)
return cpu_online(rq->mq_ctx->cpu);
}
-static void __blk_mq_put_driver_tag(struct blk_mq_hw_ctx *hctx,
- struct request *rq)
-{
- blk_mq_put_tag(hctx->tags, rq->mq_ctx, rq->tag);
- rq->tag = BLK_MQ_NO_TAG;
-
- if (rq->rq_flags & RQF_MQ_INFLIGHT) {
- rq->rq_flags &= ~RQF_MQ_INFLIGHT;
- atomic_dec(&hctx->nr_active);
- }
-}
-
-static inline void blk_mq_put_driver_tag(struct request *rq)
-{
- if (rq->tag == BLK_MQ_NO_TAG || rq->internal_tag == BLK_MQ_NO_TAG)
- return;
-
- __blk_mq_put_driver_tag(rq->mq_hctx, rq);
-}
-
bool blk_mq_complete_request_remote(struct request *rq)
{
WRITE_ONCE(rq->state, MQ_RQ_COMPLETE);
@@ -983,9 +984,10 @@ static bool blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
if (blk_mq_req_expired(rq, next))
blk_mq_rq_timed_out(rq, reserved);
- if (is_flush_rq(rq, hctx))
+ if (is_flush_rq(rq, hctx)) {
+ blk_mq_put_driver_tag(rq);
rq->end_io(rq, 0);
- else if (refcount_dec_and_test(&rq->ref))
+ } else if (refcount_dec_and_test(&rq->ref))
__blk_mq_free_request(rq);
return true;
Hmm.
Let's hope that no-one in the ->end_io() handler will need to look at
the tag, because that's gone now.
But if that fixes the flush machinery:
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@xxxxxxx +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer
