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?
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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