On 10/17/2016 12:24 PM, Sumit Saxena wrote:
> megaraid_sas driver returns SYNCHRONIZE_CACHE command back to SCSI layer
> without sending it to firmware as firmware takes care of flushing cache.
> This patch will change the driver behavior wrt SYNCHRONIZE_CACHE handling.
> If underlying firmware has support to handle the SYNCHORNIZE_CACHE, driver
> will send it for firmware otherwise complete it back to SCSI layer with
> SUCCESS immediately.
> If Firmware handle SYNCHORNIZE_CACHE for both VD and JBOD
> "canHandleSyncCache" bit in scratch pad register(offset 0x00B4) will be
> set.
>
> This behavior can be controlled via module parameter and user can fallback
> to old behavior of returning SYNCHRONIZE_CACHE by driver only without
> sending it to firmware.
>
> Signed-off-by: Sumit Saxena <sumit.saxena@xxxxxxxxxxxx>
> Signed-off-by: Kashyap Desai <kashyap.desai@xxxxxxxxxxxx>
> ---
> drivers/scsi/megaraid/megaraid_sas.h | 3 +++
> drivers/scsi/megaraid/megaraid_sas_base.c | 14 ++++++--------
> drivers/scsi/megaraid/megaraid_sas_fusion.c | 3 +++
> drivers/scsi/megaraid/megaraid_sas_fusion.h | 2 ++
> 4 files changed, 14 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 092387f..a4a8e2f 100644
> --- a/drivers/scsi/megaraid/megaraid_sas_base.c
> +++ b/drivers/scsi/megaraid/megaraid_sas_base.c
> @@ -104,6 +104,10 @@ unsigned int scmd_timeout = MEGASAS_DEFAULT_CMD_TIMEOUT;
> module_param(scmd_timeout, int, S_IRUGO);
> MODULE_PARM_DESC(scmd_timeout, "scsi command timeout (10-90s), default 90s. See megasas_reset_timer.");
>
> +bool block_sync_cache;
> +module_param(block_sync_cache, bool, S_IRUGO);
> +MODULE_PARM_DESC(block_sync_cache, "Block SYNC CACHE by driver Default: 0(Send it to firmware)");
> +
> MODULE_LICENSE("GPL");
> MODULE_VERSION(MEGASAS_VERSION);
> MODULE_AUTHOR("megaraidlinux.pdl@xxxxxxxxxxxxx");
> @@ -1700,16 +1704,10 @@ megasas_queue_command(struct Scsi_Host *shost, struct scsi_cmnd *scmd)
> 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 ((scmd->cmnd[0] == SYNCHRONIZE_CACHE) &&
> + (!instance->fw_sync_cache_support)) {
> scmd->result = DID_OK << 16;
> goto out_done;
> - 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..8237580 100644
> --- a/drivers/scsi/megaraid/megaraid_sas_fusion.c
> +++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c
> @@ -747,6 +747,9 @@ megasas_ioc_init_fusion(struct megasas_instance *instance)
> ret = 1;
> goto fail_fw_init;
> }
> + if (!block_sync_cache)
> + instance->fw_sync_cache_support = (scratch_pad_2 &
> + MR_CAN_HANDLE_SYNC_CACHE_OFFSET) ? 1 : 0;
>
> IOCInitMessage =
> dma_alloc_coherent(&instance->pdev->dev,
> diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.h b/drivers/scsi/megaraid/megaraid_sas_fusion.h
> index e3bee04..2857154 100644
> --- a/drivers/scsi/megaraid/megaraid_sas_fusion.h
> +++ b/drivers/scsi/megaraid/megaraid_sas_fusion.h
> @@ -72,6 +72,8 @@
> #define MPI2_SUP_REPLY_POST_HOST_INDEX_OFFSET (0x0000030C)
> #define MPI2_REPLY_POST_HOST_INDEX_OFFSET (0x0000006C)
>
> +extern bool block_sync_cache;
> +
> /*
> * Raid context flags
> */
>
Be extra careful with that.
SYNCHRONIZE_CACHE has (potentially) a global scope, as there might be an
array-wide cache, and a cache flush would affect the entire cache.
Linux is using SYNCHRONIZE_CACHE as a per device setting, ie it assumes
that the effects of a cache flush is restricted to the device in question.
If this is _not_ the case I'd rather not enable it.
Have you checked that enabling this functionality doesn't have negative
performance impact?
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@xxxxxxx +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)
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