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-rw-r--r--block/blk-core.c37
1 files changed, 25 insertions, 12 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index f2db628..3b02ba3 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);
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