On Tue, Jun 14, 2022 at 10:49 AM Bart Van Assche <bvanassche@xxxxxxx> wrote: > > From ZBC-2: "The device server terminates with CHECK CONDITION status, with > the sense key set to ILLEGAL REQUEST, and the additional sense code set to > UNALIGNED WRITE COMMAND a write command, other than an entire medium write > same command, that specifies: a) the starting LBA in a sequential write > required zone set to a value that is not equal to the write pointer for that > sequential write required zone; or b) an ending LBA that is not equal to the > last logical block within a physical block (see SBC-5)." > > I am not aware of any other conditions that may trigger the UNALIGNED > WRITE COMMAND response. > > Retry unaligned writes in preparation of removing zone locking. Is /just/ retrying effective here? A series of writes to the same zone would all need to be sent in order - in the worst case (requests somehow ordered in reverse order) this becomes quadratic as only 1 request "succeeds" out of the N outstanding requests, with the rest all needing to retry. (Imagine a user writes an entire "zone" - which could be split into hundreds of requests). Block layer / schedulers are free to do this reordering, which I understand does happen whenever we need to requeue - and would result in a retry of all writes after the first re-ordered request. (side note: fwiw "requests somehow in reverse order" can happen - bfq inherited cfq's odd behavior of sometimes issuing sequential IO in reverse order due to back_seek, e.g.) > > Increase the number of retries for write commands sent to a sequential > zone to the maximum number of outstanding commands. > > Cc: Martin K. Petersen <martin.petersen@xxxxxxxxxx> > Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx> > --- > drivers/scsi/scsi_error.c | 6 ++++++ > drivers/scsi/sd.c | 2 ++ > 2 files changed, 8 insertions(+) > > diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c > index 49ef864df581..8e22d4ba22a3 100644 > --- a/drivers/scsi/scsi_error.c > +++ b/drivers/scsi/scsi_error.c > @@ -674,6 +674,12 @@ enum scsi_disposition scsi_check_sense(struct scsi_cmnd *scmd) > fallthrough; > > case ILLEGAL_REQUEST: > + /* > + * Unaligned write command. Retry immediately to handle > + * out-of-order zoned writes. > + */ > + if (sshdr.asc == 0x21 && sshdr.ascq == 0x04) > + return NEEDS_RETRY; > if (sshdr.asc == 0x20 || /* Invalid command operation code */ > sshdr.asc == 0x21 || /* Logical block address out of range */ > sshdr.asc == 0x22 || /* Invalid function */ > diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c > index a1a2ac09066f..8d68bd20723e 100644 > --- a/drivers/scsi/sd.c > +++ b/drivers/scsi/sd.c > @@ -1202,6 +1202,8 @@ static blk_status_t sd_setup_read_write_cmnd(struct scsi_cmnd *cmd) > cmd->transfersize = sdp->sector_size; > cmd->underflow = nr_blocks << 9; > cmd->allowed = sdkp->max_retries; > + if (blk_rq_is_seq_write(rq)) > + cmd->allowed += rq->q->nr_hw_queues * rq->q->nr_requests; > cmd->sdb.length = nr_blocks * sdp->sector_size; > > SCSI_LOG_HLQUEUE(1,
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