block: remove non mq parts from the flush code

Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-flush.c b/block/blk-flush.c
index 8b44b86..9baa9a1 100644 (file)
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -134,16 +134,8 @@ static void blk_flush_restore_request(struct request *rq)
 
 static bool blk_flush_queue_rq(struct request *rq, bool add_front)
 {
-       if (rq->q->mq_ops) {
-               blk_mq_add_to_requeue_list(rq, add_front, true);
-               return false;
-       } else {
-               if (add_front)
-                       list_add(&rq->queuelist, &rq->q->queue_head);
-               else
-                       list_add_tail(&rq->queuelist, &rq->q->queue_head);
-               return true;
-       }
+       blk_mq_add_to_requeue_list(rq, add_front, true);
+       return false;
 }
 
 /**
@@ -204,10 +196,7 @@ static bool blk_flush_complete_seq(struct request *rq,
                BUG_ON(!list_empty(&rq->queuelist));
                list_del_init(&rq->flush.list);
                blk_flush_restore_request(rq);
-               if (q->mq_ops)
-                       blk_mq_end_request(rq, error);
-               else
-                       __blk_end_request_all(rq, error);
+               blk_mq_end_request(rq, error);
                break;
 
        default:
@@ -226,20 +215,17 @@ static void flush_end_io(struct request *flush_rq, blk_status_t error)
        struct request *rq, *n;
        unsigned long flags = 0;
        struct blk_flush_queue *fq = blk_get_flush_queue(q, flush_rq->mq_ctx);
+       struct blk_mq_hw_ctx *hctx;
 
-       if (q->mq_ops) {
-               struct blk_mq_hw_ctx *hctx;
-
-               /* release the tag's ownership to the req cloned from */
-               spin_lock_irqsave(&fq->mq_flush_lock, flags);
-               hctx = blk_mq_map_queue(q, flush_rq->mq_ctx->cpu);
-               if (!q->elevator) {
-                       blk_mq_tag_set_rq(hctx, flush_rq->tag, fq->orig_rq);
-                       flush_rq->tag = -1;
-               } else {
-                       blk_mq_put_driver_tag_hctx(hctx, flush_rq);
-                       flush_rq->internal_tag = -1;
-               }
+       /* release the tag's ownership to the req cloned from */
+       spin_lock_irqsave(&fq->mq_flush_lock, flags);
+       hctx = blk_mq_map_queue(q, flush_rq->mq_ctx->cpu);
+       if (!q->elevator) {
+               blk_mq_tag_set_rq(hctx, flush_rq->tag, fq->orig_rq);
+               flush_rq->tag = -1;
+       } else {
+               blk_mq_put_driver_tag_hctx(hctx, flush_rq);
+               flush_rq->internal_tag = -1;
        }
 
        running = &fq->flush_queue[fq->flush_running_idx];
@@ -248,9 +234,6 @@ static void flush_end_io(struct request *flush_rq, blk_status_t error)
        /* account completion of the flush request */
        fq->flush_running_idx ^= 1;
 
-       if (!q->mq_ops)
-               elv_completed_request(q, flush_rq);
-
        /* and push the waiting requests to the next stage */
        list_for_each_entry_safe(rq, n, running, flush.list) {
                unsigned int seq = blk_flush_cur_seq(rq);
@@ -259,24 +242,8 @@ static void flush_end_io(struct request *flush_rq, blk_status_t error)
                queued |= blk_flush_complete_seq(rq, fq, seq, error);
        }
 
-       /*
-        * Kick the queue to avoid stall for two cases:
-        * 1. Moving a request silently to empty queue_head may stall the
-        * queue.
-        * 2. When flush request is running in non-queueable queue, the
-        * queue is hold. Restart the queue after flush request is finished
-        * to avoid stall.
-        * This function is called from request completion path and calling
-        * directly into request_fn may confuse the driver.  Always use
-        * kblockd.
-        */
-       if (queued || fq->flush_queue_delayed) {
-               WARN_ON(q->mq_ops);
-               blk_run_queue_async(q);
-       }
        fq->flush_queue_delayed = 0;
-       if (q->mq_ops)
-               spin_unlock_irqrestore(&fq->mq_flush_lock, flags);
+       spin_unlock_irqrestore(&fq->mq_flush_lock, flags);
 }
 
 /**
@@ -301,6 +268,7 @@ static bool blk_kick_flush(struct request_queue *q, struct blk_flush_queue *fq,
        struct request *first_rq =
                list_first_entry(pending, struct request, flush.list);
        struct request *flush_rq = fq->flush_rq;
+       struct blk_mq_hw_ctx *hctx;
 
        /* C1 described at the top of this file */
        if (fq->flush_pending_idx != fq->flush_running_idx || list_empty(pending))
@@ -334,19 +302,15 @@ static bool blk_kick_flush(struct request_queue *q, struct blk_flush_queue *fq,
         * In case of IO scheduler, flush rq need to borrow scheduler tag
         * just for cheating put/get driver tag.
         */
-       if (q->mq_ops) {
-               struct blk_mq_hw_ctx *hctx;
-
-               flush_rq->mq_ctx = first_rq->mq_ctx;
-
-               if (!q->elevator) {
-                       fq->orig_rq = first_rq;
-                       flush_rq->tag = first_rq->tag;
-                       hctx = blk_mq_map_queue(q, first_rq->mq_ctx->cpu);
-                       blk_mq_tag_set_rq(hctx, first_rq->tag, flush_rq);
-               } else {
-                       flush_rq->internal_tag = first_rq->internal_tag;
-               }
+       flush_rq->mq_ctx = first_rq->mq_ctx;
+
+       if (!q->elevator) {
+               fq->orig_rq = first_rq;
+               flush_rq->tag = first_rq->tag;
+               hctx = blk_mq_map_queue(q, first_rq->mq_ctx->cpu);
+               blk_mq_tag_set_rq(hctx, first_rq->tag, flush_rq);
+       } else {
+               flush_rq->internal_tag = first_rq->internal_tag;
        }
 
        flush_rq->cmd_flags = REQ_OP_FLUSH | REQ_PREFLUSH;
@@ -358,49 +322,6 @@ static bool blk_kick_flush(struct request_queue *q, struct blk_flush_queue *fq,
        return blk_flush_queue_rq(flush_rq, false);
 }
 
-static void flush_data_end_io(struct request *rq, blk_status_t error)
-{
-       struct request_queue *q = rq->q;
-       struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL);
-
-       lockdep_assert_held(q->queue_lock);
-
-       /*
-        * Updating q->in_flight[] here for making this tag usable
-        * early. Because in blk_queue_start_tag(),
-        * q->in_flight[BLK_RW_ASYNC] is used to limit async I/O and
-        * reserve tags for sync I/O.
-        *
-        * More importantly this way can avoid the following I/O
-        * deadlock:
-        *
-        * - suppose there are 40 fua requests comming to flush queue
-        *   and queue depth is 31
-        * - 30 rqs are scheduled then blk_queue_start_tag() can't alloc
-        *   tag for async I/O any more
-        * - all the 30 rqs are completed before FLUSH_PENDING_TIMEOUT
-        *   and flush_data_end_io() is called
-        * - the other rqs still can't go ahead if not updating
-        *   q->in_flight[BLK_RW_ASYNC] here, meantime these rqs
-        *   are held in flush data queue and make no progress of
-        *   handling post flush rq
-        * - only after the post flush rq is handled, all these rqs
-        *   can be completed
-        */
-
-       elv_completed_request(q, rq);
-
-       /* for avoiding double accounting */
-       rq->rq_flags &= ~RQF_STARTED;
-
-       /*
-        * After populating an empty queue, kick it to avoid stall.  Read
-        * the comment in flush_end_io().
-        */
-       if (blk_flush_complete_seq(rq, fq, REQ_FSEQ_DATA, error))
-               blk_run_queue_async(q);
-}
-
 static void mq_flush_data_end_io(struct request *rq, blk_status_t error)
 {
        struct request_queue *q = rq->q;
@@ -443,9 +364,6 @@ void blk_insert_flush(struct request *rq)
        unsigned int policy = blk_flush_policy(fflags, rq);
        struct blk_flush_queue *fq = blk_get_flush_queue(q, rq->mq_ctx);
 
-       if (!q->mq_ops)
-               lockdep_assert_held(q->queue_lock);
-
        /*
         * @policy now records what operations need to be done.  Adjust
         * REQ_PREFLUSH and FUA for the driver.
@@ -468,10 +386,7 @@ void blk_insert_flush(struct request *rq)
         * complete the request.
         */
        if (!policy) {
-               if (q->mq_ops)
-                       blk_mq_end_request(rq, 0);
-               else
-                       __blk_end_request(rq, 0, 0);
+               blk_mq_end_request(rq, 0);
                return;
        }
 
@@ -484,10 +399,7 @@ void blk_insert_flush(struct request *rq)
         */
        if ((policy & REQ_FSEQ_DATA) &&
            !(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH))) {
-               if (q->mq_ops)
-                       blk_mq_request_bypass_insert(rq, false);
-               else
-                       list_add_tail(&rq->queuelist, &q->queue_head);
+               blk_mq_request_bypass_insert(rq, false);
                return;
        }
 
@@ -499,17 +411,12 @@ void blk_insert_flush(struct request *rq)
        INIT_LIST_HEAD(&rq->flush.list);
        rq->rq_flags |= RQF_FLUSH_SEQ;
        rq->flush.saved_end_io = rq->end_io; /* Usually NULL */
-       if (q->mq_ops) {
-               rq->end_io = mq_flush_data_end_io;
 
-               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;
-       }
-       rq->end_io = flush_data_end_io;
+       rq->end_io = mq_flush_data_end_io;
 
+       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);
 }
 
 /**
@@ -575,8 +482,7 @@ struct blk_flush_queue *blk_alloc_flush_queue(struct request_queue *q,
        if (!fq)
                goto fail;
 
-       if (q->mq_ops)
-               spin_lock_init(&fq->mq_flush_lock);
+       spin_lock_init(&fq->mq_flush_lock);
 
        rq_sz = round_up(rq_sz + cmd_size, cache_line_size());
        fq->flush_rq = kzalloc_node(rq_sz, flags, node);

diff --git a/block/blk.h b/block/blk.h
index a1841b8..57a302b 100644 (file)
--- a/block/blk.h
+++ b/block/blk.h
@@ -114,9 +114,7 @@ static inline void queue_flag_clear(unsigned int flag, struct request_queue *q)
 static inline struct blk_flush_queue *blk_get_flush_queue(
                struct request_queue *q, struct blk_mq_ctx *ctx)
 {
-       if (q->mq_ops)
-               return blk_mq_map_queue(q, ctx->cpu)->fq;
-       return q->fq;
+       return blk_mq_map_queue(q, ctx->cpu)->fq;
 }
 
 static inline void __blk_get_queue(struct request_queue *q)