On 8/17/17 16:59, Christoph Hellwig wrote: > On Thu, Aug 17, 2017 at 11:45:50AM +0900, Damien Le Moal wrote: >> blk-mq may not maintain write requests order at dispatch time. So host >> managed drives will not reliably work. Worse, potential reordering of >> write requests on requeue may cause the zone write locking code to >> deadlock command dispatch to the disk. So for now, until the write >> ordering issue is fixed, do not support zoned block devices with >> scsi-mq by showing a 0 LBA capacity disk. > > NAK. Please fix the issue instead of this.
I do have a fix ready to send. All the fixes are at blk-mq level and basically ensure that dispatch from the hctx->dispatch list are in order for write commands (regular writes, write same and write zeroes). It is well tested and at least fixes all the problems I have seen with dm-zoned and f2fs. But: 1) It is not small, so I strongly doubt it is RC material 2) We need Bart's patch for "always unprepare requests" which was reverted 3) Bart does not really like the solution I implemented... I can still send it if you want to have a look. Best. -- Damien Le Moal, Western Digital Research
