On Wed, Sep 27, 2017 at 03:43:11AM +0000, Bart Van Assche wrote: > On Wed, 2017-09-27 at 06:23 +0800, Ming Lei wrote: > > mutex_lock(&sdev->state_mutex); > > err = scsi_device_set_state(sdev, SDEV_QUIESCE); > > if (err == 0) > > blk_set_preempt_only(q, true); > > mutex_unlock(&sdev->state_mutex); > > > > if (err) > > return err; > > > > blk_mq_freeze_queue(q); > > blk_mq_unfreeze_queue(q); > > > > Any requests allocated before scsi_device_set_state() and > > dispatched after scsi_device_set_state() can't be drained up > > any more, then blk_mq_freeze_queue() will wait forever for the > > drain up, so not only this patchset can't fix the current quiesce > > issue, but also introduces new I/O hang in scsi_device_quiesce(). > > That's a good catch, but fortunately this is very easy to fix: move the > blk_mq_freeze_queue() call before the mutex_lock() and scsi_device_set_state() > calls. The error path will also need some adjustment.
I am also working towards that direction, patches have been ready. -- Ming
