blk-mq: don't insert FUA request with data into scheduler queue

We never insert flush request into scheduler queue before.

Recently commit d92ca9d8348f ("blk-mq: don't handle non-flush requests in
blk_insert_flush") tries to handle FUA data request as normal request.
This way has caused warning[1] in mq-deadline dd_exit_sched() or io hang in
case of kyber since RQF_ELVPRIV isn't set for flush request, then
->finish_request won't be called.

Fix the issue by inserting FUA data request with blk_mq_request_bypass_insert()
when the device supports FUA, just like what we did before.

[1] https://lore.kernel.org/linux-block/CAHj4cs-_vkTW=dAzbZYGxpEWSpzpcmaNeY1R=vH311+9vMUSdg@mail.gmail.com/

Reported-by: Yi Zhang <yi.zhang@redhat.com>
Fixes: d92ca9d8348f ("blk-mq: don't handle non-flush requests in blk_insert_flush")
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20211118153041.2163228-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-flush.c b/block/blk-flush.c
index 8e364bd..1fce6d1 100644 (file)
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -379,7 +379,7 @@ static void mq_flush_data_end_io(struct request *rq, blk_status_t error)
  * @rq is being submitted.  Analyze what needs to be done and put it on the
  * right queue.
  */
-bool blk_insert_flush(struct request *rq)
+void blk_insert_flush(struct request *rq)
 {
        struct request_queue *q = rq->q;
        unsigned long fflags = q->queue_flags;  /* may change, cache */
@@ -409,7 +409,7 @@ bool blk_insert_flush(struct request *rq)
         */
        if (!policy) {
                blk_mq_end_request(rq, 0);
-               return true;
+               return;
        }
 
        BUG_ON(rq->bio != rq->biotail); /*assumes zero or single bio rq */
@@ -420,8 +420,10 @@ bool blk_insert_flush(struct request *rq)
         * for normal execution.
         */
        if ((policy & REQ_FSEQ_DATA) &&
-           !(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH)))
-               return false;
+           !(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH))) {
+               blk_mq_request_bypass_insert(rq, false, true);
+               return;
+       }
 
        /*
         * @rq should go through flush machinery.  Mark it part of flush
@@ -437,8 +439,6 @@ bool blk_insert_flush(struct request *rq)
        spin_lock_irq(&fq->mq_flush_lock);
        blk_flush_complete_seq(rq, fq, REQ_FSEQ_ACTIONS & ~policy, 0);
        spin_unlock_irq(&fq->mq_flush_lock);
-
-       return true;
 }
 
 /**

diff --git a/block/blk-mq.c b/block/blk-mq.c
index eecbd7e..8799fa7 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2647,8 +2647,10 @@ void blk_mq_submit_bio(struct bio *bio)
                return;
        }
 
-       if (op_is_flush(bio->bi_opf) && blk_insert_flush(rq))
+       if (op_is_flush(bio->bi_opf)) {
+               blk_insert_flush(rq);
                return;
+       }
 
        if (plug && (q->nr_hw_queues == 1 ||
            blk_mq_is_shared_tags(rq->mq_hctx->flags) ||

diff --git a/block/blk.h b/block/blk.h
index b4fed20..ccde6e6 100644 (file)
--- a/block/blk.h
+++ b/block/blk.h
@@ -271,7 +271,7 @@ void __blk_account_io_done(struct request *req, u64 now);
  */
 #define ELV_ON_HASH(rq) ((rq)->rq_flags & RQF_HASHED)
 
-bool blk_insert_flush(struct request *rq);
+void blk_insert_flush(struct request *rq);
 
 int elevator_switch_mq(struct request_queue *q,
                              struct elevator_type *new_e);