On Wed, Mar 29, 2017 at 05:09:37AM +0200, Linus Walleij wrote: > 2. When MMC cards are ejected a serious error condition occurs. So for this > reason we spool out the queue with > > req->rq_flags |= RQF_QUIET; > blk_end_request_all(req, -EIO); > > This will shut up a huge amount of console errors for example. > I have no clue on how to manage this with MQ. I am currently using > > blk_mq_complete_request(mq_rq->req, -EIO); > > and nothing else, and it will hit all requests for the ejected card coming > in from this point. Is this the right solution? Or is there some medium > eject handling I'm not aware of inside the MQ layer? It seems like something > that can happen on pluggable harddrives and CDROMS and what not.
Hot unplug handling currently is a mess in the block layer (not just the mq case). Especially if you ever requeue an I/O there is tons of boilerplate code. I wish we could move a little more of this into the core, but right now I don't have a good idea on how to. > 3. Sometimes a read or write gets partially completed. Say we read 12 out > of 15 sectors or somthing like that. I have no idea how often this occurs in > practice. With the old block layer we did this: > > blk_end_request(req, 0, bytes_xfered); You can still do this with mq, but you have to open code it. Take a look at scsi_end_request which has opencoded versions of the mq and non-mq end_request routines. Currently it's the only example of blk-mq partial completions.
