blk-mq: allocate flush_rq in blk_mq_init_flush()

It is reasonable to allocate flush req in blk_mq_init_flush().

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

3 files changed, 17 insertions, 12 deletions

diff --git a/block/blk-flush.c b/block/blk-flush.c
index c8e25768f2e1..55028a707927 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -472,7 +472,16 @@ int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
 }
 EXPORT_SYMBOL(blkdev_issue_flush);
 
-void blk_mq_init_flush(struct request_queue *q)
+int blk_mq_init_flush(struct request_queue *q)
 {
+        struct blk_mq_tag_set *set = q->tag_set;
+
         spin_lock_init(&q->mq_flush_lock);
+
+        q->flush_rq = kzalloc(round_up(sizeof(struct request) +
+                                set->cmd_size, cache_line_size()),
+                                GFP_KERNEL);
+        if (!q->flush_rq)
+                return -ENOMEM;
+        return 0;
 }
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 66ef1fb79326..78bcf8bfb22a 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1848,17 +1848,10 @@ struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
         if (set->ops->complete)
                 blk_queue_softirq_done(q, set->ops->complete);
 
-        blk_mq_init_flush(q);
         blk_mq_init_cpu_queues(q, set->nr_hw_queues);
 
-        q->flush_rq = kzalloc(round_up(sizeof(struct request) +
-                                set->cmd_size, cache_line_size()),
-                                GFP_KERNEL);
-        if (!q->flush_rq)
-                goto err_hw;
-
         if (blk_mq_init_hw_queues(q, set))
-                goto err_flush_rq;
+                goto err_hw;
 
         mutex_lock(&all_q_mutex);
         list_add_tail(&q->all_q_node, &all_q_list);
@@ -1866,12 +1859,15 @@ struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
 
         blk_mq_add_queue_tag_set(set, q);
 
+        if (blk_mq_init_flush(q))
+                goto err_hw_queues;
+
         blk_mq_map_swqueue(q);
 
         return q;
 
-err_flush_rq:
-        kfree(q->flush_rq);
+err_hw_queues:
+        blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
 err_hw:
         blk_cleanup_queue(q);
 err_hctxs:
diff --git a/block/blk-mq.h b/block/blk-mq.h
index a3c613a9df2d..ecac69c08937 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -27,7 +27,7 @@ struct blk_mq_ctx {
 
 void __blk_mq_complete_request(struct request *rq);
 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async);
-void blk_mq_init_flush(struct request_queue *q);
+int blk_mq_init_flush(struct request_queue *q);
 void blk_mq_freeze_queue(struct request_queue *q);
 void blk_mq_free_queue(struct request_queue *q);
 void blk_mq_clone_flush_request(struct request *flush_rq,