On 21.10.2016 13:01, James Bottomley wrote:
> On Thu, 2016-10-20 at 02:05 -0700, Sumit Saxena wrote:
>> From previous patch we have below changes in v2 -
>> 1. Updated change log. Provided more detail in change log.
>> 2. Agreed to remove module parameter. If we remove module parameter,
>> we
>> can ask customer to disable WCE on drive to get similar impact.
>> 3. Always Send SYNCHRONIZE_CACHE for JBOD (non Raid) Device to
>> Firmware.
>>
>> Current megaraid_sas driver returns SYNCHRONIZE_CACHE(related to
>> Drive
>> Cache) command back to SCSI layer without sending it down to
>> firmware as
>> firmware supposed to take care of flushing disk cache for all drives
>> belongs to Virtual Disk at the time of system reboot/shutdown.
>>
>> We evaluate and understood that for Raid Volume, why driver should
>> not
>> send SYNC_CACHE command to the Firmware.
>> There may be a some reason in past, but now it looks to be not
>> required and
>> we have fixed this issue as part of this patch.
>>
>> Commit- " 02b01e0 [SCSI] megaraid_sas: return sync cache call with
>> success"
>> added the code in driver to return SYNCHRONIZE_CACHE without sending
>> it to
>> firmware back in 2007. Earlier MR was mainly for Virtual Disk,
>> so same code continue for JBOD as well whenever JBOD support was
>> added and it introduced bug that
>> SYNCHRONIZE_CACHE is not passed to FW for JBOD (non Raid disk).
>>
>> But our recent analysis indicates that, From Day-1 MR Firmware always
>> expect Driver to forward SYNCHRONIZE_CACHE for JBOD (non Raid disk)
>> to the
>> Firmware.
>> We have fixed this as part of this patch.
>>
>> - Additional background -
>> There are some instance of MegaRaid FW (E.a Gen2 and Gen2.5 FW) set
>> WCE bit
>> for Virtual Disk but firmware does not reply correct status for
>> SYNCH_CACHE.
>> It is very difficult to find out which Device ID and firmware has
>> capability
>> to manage SYNC_CACHE, so we managed to figure out which are the new
>> firmware
>> (canHandleSyncCache is set in scratch pad register at 0xB4) and use
>> that
>> interface for correct behavior as explained above.
>>
>> E.g Liberator/Thunderbolt MegaRaid FW returns SYNC_CACHE as
>> Unsupported
>> command (this is a firmware bug) and eventually command will be
>> failed to SML.
>> This will cause File system to go Read-only.
>>
>> - New behavior described -
>>
>> IF application requests SYNCH_CACHE
>> IF 'JBOD'
>> Driver sends SYNCH_CACHE command to the FW
>> FW sends SYNCH_CACHE to drive
>> FW obtains status from drive and returns same status
>> back to driver
>> ELSEIF 'VirtualDisk'
>> IF any FW which supports new API bit called
>> canHandleSyncCache
>> Driver sends SYNCH_CACHE command to the
>> FW
>> FW does not send SYNCH_CACHE to drives
>> FW returns SUCCESS
>> ELSE
>> Driver does not send SYNCH_CACHE
>> command to the FW.
>> Driver return SUCCESS for that command.
>> ENDIF
>> ENDIF
>> ENDIF
>>
>> CC: stable@xxxxxxxxxxxxxxx
> Can you please split this into two, so we can backport the bug fix
> without any of the feature addition junk?
>
>> Signed-off-by: Kashyap Desai <kashyap.desai@xxxxxxxxxxxx>
>> Signed-off-by: Sumit Saxena <sumit.saxena@xxxxxxxxxxxx>
>> ---
>> drivers/scsi/megaraid/megaraid_sas.h | 3 +++
>> drivers/scsi/megaraid/megaraid_sas_base.c | 10 ++--------
>> drivers/scsi/megaraid/megaraid_sas_fusion.c | 5 +++++
>> 3 files changed, 10 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/scsi/megaraid/megaraid_sas.h
>> b/drivers/scsi/megaraid/megaraid_sas.h
>> index ca86c88..43fd14f 100644
>> --- a/drivers/scsi/megaraid/megaraid_sas.h
>> +++ b/drivers/scsi/megaraid/megaraid_sas.h
>> @@ -1429,6 +1429,8 @@ enum FW_BOOT_CONTEXT {
>> #define MR_MAX_REPLY_QUEUES_EXT_OFFSET_SHIFT 14
>> #define MR_MAX_MSIX_REG_ARRAY 16
>> #define MR_RDPQ_MODE_OFFSET 0X00800000
>> +#define MR_CAN_HANDLE_SYNC_CACHE_OFFSET 0X01000000
>> +
>> /*
>> * register set for both 1068 and 1078 controllers
>> * structure extended for 1078 registers
>> @@ -2140,6 +2142,7 @@ struct megasas_instance {
>> u8 is_imr;
>> u8 is_rdpq;
>> bool dev_handle;
>> + bool fw_sync_cache_support;
>> };
>> struct MR_LD_VF_MAP {
>> u32 size;
>> diff --git a/drivers/scsi/megaraid/megaraid_sas_base.c
>> b/drivers/scsi/megaraid/megaraid_sas_base.c
>> index 3236632..f7a2ab1 100644
>> --- a/drivers/scsi/megaraid/megaraid_sas_base.c
>> +++ b/drivers/scsi/megaraid/megaraid_sas_base.c
>> @@ -1700,16 +1700,10 @@ inline int megasas_cmd_type(struct scsi_cmnd
>> *cmd)
>> goto out_done;
>> }
>>
>> - switch (scmd->cmnd[0]) {
>> - case SYNCHRONIZE_CACHE:
>> - /*
>> - * FW takes care of flush cache on its own
>> - * No need to send it down
>> - */
>> + if (MEGASAS_IS_LOGICAL(scmd) && (scmd->cmnd[0] ==
>> SYNCHRONIZE_CACHE) &&
>> + (!instance->fw_sync_cache_support)) {
>> scmd->result = DID_OK << 16;
>> goto out_done;
> This, minus the "&& (!instance->fw_sync_cache_support)" is all we need
> for the bug fix, correct?
Isn't both a) sending SYNC to JBOD and b) sending SYNC to logical luns
a bugfix of the same kind?
>
> James
>
>> - default:
>> - break;
>> }
>>
>> return instance->instancet->build_and_issue_cmd(instance,
>> scmd);
>> diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c
>> b/drivers/scsi/megaraid/megaraid_sas_fusion.c
>> index 2159f6a..2e61306 100644
>> --- a/drivers/scsi/megaraid/megaraid_sas_fusion.c
>> +++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c
>> @@ -748,6 +748,11 @@ static int megasas_create_sg_sense_fusion(struct
>> megasas_instance *instance)
>> goto fail_fw_init;
>> }
>>
>> + instance->fw_sync_cache_support = (scratch_pad_2 &
>> + MR_CAN_HANDLE_SYNC_CACHE_OFFSET) ? 1 : 0;
>> + dev_info(&instance->pdev->dev, "FW supports sync cache\t:
>> %s\n",
>> + instance->fw_sync_cache_support ? "Yes" : "No");
>> +
>> IOCInitMessage =
>> dma_alloc_coherent(&instance->pdev->dev,
>> sizeof(struct MPI2_IOC_INIT_REQUEST),
> --
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