block: extend queue bypassing to cover blkcg policies
Extend queue bypassing such that dying queue is always bypassing and
blk-throttle is drained on bypass. With blkcg policies updated to
test blk_queue_bypass() instead of blk_queue_dead(), this ensures that
no bio or request is held by or going through blkcg policies on a
bypassing queue.
This will be used to implement blkg cleanup on elevator switches and
policy changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-core.c b/block/blk-core.c
index 98ddef4..7713c73 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -372,8 +372,7 @@
if (q->elevator)
elv_drain_elevator(q);
- if (drain_all)
- blk_throtl_drain(q);
+ blk_throtl_drain(q);
/*
* This function might be called on a queue which failed
@@ -415,8 +414,8 @@
*
* In bypass mode, only the dispatch FIFO queue of @q is used. This
* function makes @q enter bypass mode and drains all requests which were
- * issued before. On return, it's guaranteed that no request has ELVPRIV
- * set.
+ * throttled or issued before. On return, it's guaranteed that no request
+ * is being throttled or has ELVPRIV set.
*/
void blk_queue_bypass_start(struct request_queue *q)
{
@@ -461,6 +460,11 @@
queue_flag_set_unlocked(QUEUE_FLAG_DEAD, q);
spin_lock_irq(lock);
+
+ /* dead queue is permanently in bypass mode till released */
+ q->bypass_depth++;
+ queue_flag_set(QUEUE_FLAG_BYPASS, q);
+
queue_flag_set(QUEUE_FLAG_NOMERGES, q);
queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
queue_flag_set(QUEUE_FLAG_DEAD, q);