diff options
| -rw-r--r-- | block/blk-core.c | 37 |
1 files changed, 25 insertions, 12 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index f2db628aa509..3b02ba351f8c 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -421,14 +421,18 @@ void blk_drain_queue(struct request_queue *q, bool drain_all) */ void blk_queue_bypass_start(struct request_queue *q) { + bool drain; + spin_lock_irq(q->queue_lock); - q->bypass_depth++; + drain = !q->bypass_depth++; queue_flag_set(QUEUE_FLAG_BYPASS, q); spin_unlock_irq(q->queue_lock); - blk_drain_queue(q, false); - /* ensure blk_queue_bypass() is %true inside RCU read lock */ - synchronize_rcu(); + if (drain) { + blk_drain_queue(q, false); + /* ensure blk_queue_bypass() is %true inside RCU read lock */ + synchronize_rcu(); + } } EXPORT_SYMBOL_GPL(blk_queue_bypass_start); @@ -577,6 +581,15 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) */ q->queue_lock = &q->__queue_lock; + /* + * A queue starts its life with bypass turned on to avoid + * unnecessary bypass on/off overhead and nasty surprises during + * init. The initial bypass will be finished at the end of + * blk_init_allocated_queue(). + */ + q->bypass_depth = 1; + __set_bit(QUEUE_FLAG_BYPASS, &q->queue_flags); + if (blkcg_init_queue(q)) goto fail_id; @@ -672,15 +685,15 @@ blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn, q->sg_reserved_size = INT_MAX; - /* - * all done - */ - if (!elevator_init(q, NULL)) { - blk_queue_congestion_threshold(q); - return q; - } + /* init elevator */ + if (elevator_init(q, NULL)) + return NULL; - return NULL; + blk_queue_congestion_threshold(q); + + /* all done, end the initial bypass */ + blk_queue_bypass_end(q); + return q; } EXPORT_SYMBOL(blk_init_allocated_queue); |