lkml.org 
[lkml]   [2020]   [Aug]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH v1] scsi: libsas: set data_dir as DMA_NONE if libata mark qc as NODATA
    From
    Date

    在 2020/8/26 15:24, Luo Jiaxing 写道:
    > We found that it will fail every time when set feature to SATA disk by
    > "sdparm -s WCE=0 /dev/sde".
    >
    > After checking protocol, we know that MODE SELECT is the SCSI command for
    > setting WCE, and it do not exist in the SATA protocol. Therefore, this
    > commands are encapsulated in the SET FEATURE command in SATA protocol.
    > The difference is that the MODE SELECT command sent to SAS disk contains
    > data and is sent through the DMA. But when send to SATA disk through
    > SET FEATURE command, it does not contain data.
    >
    > I think libsas was not thorough enough in dealing with the situation, at
    > sas_ata_qc_issue(), task->dma_dir is inherited from qc->dma_dir(qc->dma_dir
    > is also inherited from SCSI). However, in ATA driver, if qc->tf.protocol is
    > set to ATA_PROT_NODATA, ata_sg_setup() will not invoked by ata_qc_issue().
    > It mean that ATA didn't use dma_dir and it's not reliable. So, if libsas
    > still inherits from qc->dma_dir when there is no data need to be send. As a
    > result, task with no data are mistakenly considered as carrying data and it
    > will make LLDD report an error on IO completion.
    >
    > So, When ATA driver mark tf->protocol as NODATA, dma_dir should be set as
    > DMA_NONE. And we can see WCE is successfully disable for SATA disk then.
    >
    > Euler:~ # sdparm -s WCE=0 /dev/sde
    > /dev/sde: ATA ST4000NM0035-1V4 TN03
    > Euler:~ # sdparm /dev/sde
    > /dev/sde: ATA ST4000NM0035-1V4 TN03
    > Read write error recovery mode page:
    > AWRE 1 [cha: n, def: 1]
    > ARRE 0 [cha: n, def: 0]
    > PER 0 [cha: n, def: 0]
    > Caching (SBC) mode page:
    > WCE 0 [cha: y, def: 0]
    > RCD 0 [cha: n, def: 0]
    > Control mode page:
    > SWP 0 [cha: n, def: 0]
    >
    > Fixes: fa1c1e8f1ece ("[SCSI] Add SATA support to libsas")
    >
    > Signed-off-by: Luo Jiaxing <luojiaxing@huawei.com>
    > Reviewed-by: John Garry <john.garry@huawei.com>
    > ---
    > drivers/scsi/libsas/sas_ata.c | 5 ++++-
    > 1 file changed, 4 insertions(+), 1 deletion(-)
    >
    > diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
    > index 6a521ba..a488798 100644
    > --- a/drivers/scsi/libsas/sas_ata.c
    > +++ b/drivers/scsi/libsas/sas_ata.c
    > @@ -209,7 +209,10 @@ static unsigned int sas_ata_qc_issue(struct ata_queued_cmd *qc)
    > task->num_scatter = si;
    > }
    >
    > - task->data_dir = qc->dma_dir;
    > + if (qc->tf.protocol == ATA_PROT_NODATA)
    > + task->data_dir = DMA_NONE;
    > + else
    > + task->data_dir = qc->dma_dir;
    > task->scatter = qc->sg;
    > task->ata_task.retry_count = 1;
    > task->task_state_flags = SAS_TASK_STATE_PENDING;
    >

    Reviewed-by: Jason Yan <yanaijie@huawei.com>

    \
     
     \ /
      Last update: 2020-08-31 09:30    [W:3.026 / U:0.604 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site