Hello, Good day. My inquiry is about block drivers. Suppose our device encounter problems and all error handling failed. The only remaining option I see for the driver to do is to offline it. The intention is for the system to be notified to avoid sending any future request to the device and be inaccessible so any wicked behavior, like system crash, are avoided. This should work whether the device is used standalone or with RAID. The question is how to do it cleanly. I've searched existing drivers in the kernel source (like sd, skd, etc), and all they do (as I see it) is to complete succeeding requests with -EIO (__blk_end_request_all(rq, -EIO)). So far this works with FIO, because once that happens and all fio requests are completed with -EIO, fio stops sending further requests. But if used with RAID and unrecoverable fault is triggered, just completing requests with error seems not to be working. RAID detects errors, but can't remove the erring device from its system. Sometimes kernel is still sending requests to the RAID'ed faulty device (which should stop). RAID becomes degraded (in a not-so-good way) and eventually crashes the system. So how does the block driver properly informs the upper layers that its device is faulty and must not be used again for that session? Best regards, Alvin