This small series addresses a couple of problems detected with 4.13-rc. The first patch ensures that a well behaved host managed zoned block device user (an application doing direct disk accesses, f2fs or dm-zoned) will not see unaligned write errors due to reordering of write commands at dispatch time. The second patch addresses a request dispatch deadlock that can very easily trigger with f2fs or dm-zoned when scsi-mq is enabled. The root cause of this problem is the high probability of unintended reordering of sequential writes in the dispatch queue due to concurrent requeue and insert events. This patch only fixes the deadlock problem and is not a fix for the root cause itself, which will require most likely a different approach as no easy fix seem to be possible at the scsi-mq level. This means that host managed zoned block devices cannot be reliably used under a regular asynchronous (queued) write BIO issuing pattern with scsi-mq enabled for now. Damien Le Moal (1): sd_zbc: Disable zone locking with scsi-mq enabled Hannes Reinecke (1): block: Zoned block device single-threaded submission block/blk-core.c | 7 +++++++ drivers/scsi/sd_zbc.c | 7 ++++++- 2 files changed, 13 insertions(+), 1 deletion(-) -- 2.13.3
