On 3/4/22 08:03, Christoph Hellwig wrote:
From: Ming Lei <ming.lei@xxxxxxxxxx>
There can't be FS IO in disk_release(), so it is safe to move rq_qos_exit()
there.
The commit message only explains why it is safe to move rq_qos_exit()
but not why moving that function call is useful. Please add an
explanation of why moving that function call is useful and/or necessary.
diff --git a/block/genhd.c b/block/genhd.c
index 857e0a54da7dd..56f66c6fee943 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -627,7 +627,6 @@ void del_gendisk(struct gendisk *disk)
blk_mq_freeze_queue_wait(q);
- rq_qos_exit(q);
blk_sync_queue(q);
blk_flush_integrity();
/*
@@ -1119,7 +1118,7 @@ static void disk_release_mq(struct request_queue *q)
elevator_exit(q);
mutex_unlock(&q->sysfs_lock);
}
-
+ rq_qos_exit(q);
__blk_mq_unfreeze_queue(q, true);
}
Commit 8e141f9eb803 ("block: drain file system I/O on del_gendisk")
removed the rq_qos_exit() call from blk_cleanup_queue(). This patch
series does not restore the rq_qos_exit() call in blk_cleanup_queue(). I
think that call should be restored since rq_qos_add() can be called
before add_disk() is called. I'm referring to the following call chain:
__alloc_disk_node()
blkcg_init_queue()
blk_iolatency_init()
rq_qos_add()
sd_probe() is one of the functions that can take an error path after
__alloc_disk_node() has returned and before device_add_disk() is called.
Thanks,
Bart.
