[PATCH 3/3] zfcp: support for hardware data router

Steffen Maier
2011-08-15T12:40:32Z

[-- Attachment #1: 3.2/702-zfcp-data-router.diff --]
[-- Type: text/plain, Size: 16971 bytes --]

From: Swen Schillig <swen@vnet.ibm.com>

FICON Express8S supports hardware data router, which requires an
adapted qdio request format.
This part 2/2 exploits the functionality in zfcp.

Signed-off-by: Swen Schillig <swen@vnet.ibm.com>
Signed-off-by: Steffen Maier <maier@linux.vnet.ibm.com>
---

drivers/s390/scsi/zfcp_dbf.c | 36 +++++++++++++++++++
drivers/s390/scsi/zfcp_def.h | 7 +++
drivers/s390/scsi/zfcp_ext.h | 1
drivers/s390/scsi/zfcp_fsf.c | 77 +++++++++++++++++++++++++-----------------
drivers/s390/scsi/zfcp_qdio.c | 58 ++++++++++++++++++++++++++-----
drivers/s390/scsi/zfcp_qdio.h | 66 +++++++++++++++++++++++++++---------
drivers/s390/scsi/zfcp_scsi.c | 10 ++---
7 files changed, 195 insertions(+), 60 deletions(-)

--- a/drivers/s390/scsi/zfcp_dbf.c
+++ b/drivers/s390/scsi/zfcp_dbf.c
@@ -163,6 +163,42 @@ void zfcp_dbf_hba_bit_err(char *tag, str
spin_unlock_irqrestore(&dbf->hba_lock, flags);
}

+/**
+ * zfcp_dbf_hba_def_err - trace event for deferred error messages
+ * @adapter: pointer to struct zfcp_adapter
+ * @req_id: request id which caused the deferred error message
+ * @scount: number of sbals incl. the signaling sbal
+ * @pl: array of all involved sbals
+ */
+void zfcp_dbf_hba_def_err(struct zfcp_adapter *adapter, u64 req_id, u16 scount,
+ void **pl)
+{
+ struct zfcp_dbf *dbf = adapter->dbf;
+ struct zfcp_dbf_pay *payload = &dbf->pay_buf;
+ unsigned long flags;
+ u16 length;
+
+ if (!pl)
+ return;
+
+ spin_lock_irqsave(&dbf->pay_lock, flags);
+ memset(payload, 0, sizeof(*payload));
+
+ memcpy(payload->area, "def_err", 7);
+ payload->fsf_req_id = req_id;
+ payload->counter = 0;
+ length = min((u16)sizeof(struct qdio_buffer),
+ (u16)ZFCP_DBF_PAY_MAX_REC);
+
+ while ((char *)pl[payload->counter] && payload->counter < scount) {
+ memcpy(payload->data, (char *)pl[payload->counter], length);
+ debug_event(dbf->pay, 1, payload, zfcp_dbf_plen(length));
+ payload->counter++;
+ }
+
+ spin_unlock_irqrestore(&dbf->pay_lock, flags);
+}
+
static void zfcp_dbf_set_common(struct zfcp_dbf_rec *rec,
struct zfcp_adapter *adapter,
struct zfcp_port *port,
--- a/drivers/s390/scsi/zfcp_def.h
+++ b/drivers/s390/scsi/zfcp_def.h
@@ -72,6 +72,7 @@ struct zfcp_reqlist;
#define ZFCP_STATUS_COMMON_NOESC 0x00200000

/* adapter status */
+#define ZFCP_STATUS_ADAPTER_MB_ACT 0x00000001
#define ZFCP_STATUS_ADAPTER_QDIOUP 0x00000002
#define ZFCP_STATUS_ADAPTER_SIOSL_ISSUED 0x00000004
#define ZFCP_STATUS_ADAPTER_XCONFIG_OK 0x00000008
@@ -314,4 +315,10 @@ struct zfcp_fsf_req {
void (*handler)(struct zfcp_fsf_req *);
};

+static inline
+int zfcp_adapter_multi_buffer_active(struct zfcp_adapter *adapter)
+{
+ return atomic_read(&adapter->status) & ZFCP_STATUS_ADAPTER_MB_ACT;
+}
+
#endif /* ZFCP_DEF_H */
--- a/drivers/s390/scsi/zfcp_ext.h
+++ b/drivers/s390/scsi/zfcp_ext.h
@@ -53,6 +53,7 @@ extern void zfcp_dbf_hba_fsf_uss(char *,
extern void zfcp_dbf_hba_fsf_res(char *, struct zfcp_fsf_req *);
extern void zfcp_dbf_hba_bit_err(char *, struct zfcp_fsf_req *);
extern void zfcp_dbf_hba_berr(struct zfcp_dbf *, struct zfcp_fsf_req *);
+extern void zfcp_dbf_hba_def_err(struct zfcp_adapter *, u64, u16, void **);
extern void zfcp_dbf_san_req(char *, struct zfcp_fsf_req *, u32);
extern void zfcp_dbf_san_res(char *, struct zfcp_fsf_req *);
extern void zfcp_dbf_san_in_els(char *, struct zfcp_fsf_req *);
--- a/drivers/s390/scsi/zfcp_fsf.c
+++ b/drivers/s390/scsi/zfcp_fsf.c
@@ -936,39 +936,47 @@ static int zfcp_fsf_setup_ct_els_sbals(s
struct scatterlist *sg_resp)
{
struct zfcp_adapter *adapter = req->adapter;
+ struct zfcp_qdio *qdio = adapter->qdio;
+ struct fsf_qtcb *qtcb = req->qtcb;
u32 feat = adapter->adapter_features;
- int bytes;

- if (!(feat & FSF_FEATURE_ELS_CT_CHAINED_SBALS)) {
- if (!zfcp_qdio_sg_one_sbale(sg_req) ||
- !zfcp_qdio_sg_one_sbale(sg_resp))
- return -EOPNOTSUPP;
+ if (zfcp_adapter_multi_buffer_active(adapter)) {
+ if (zfcp_qdio_sbals_from_sg(qdio, &req->qdio_req, sg_req))
+ return -EIO;
+ if (zfcp_qdio_sbals_from_sg(qdio, &req->qdio_req, sg_resp))
+ return -EIO;

- zfcp_fsf_setup_ct_els_unchained(adapter->qdio, &req->qdio_req,
- sg_req, sg_resp);
+ zfcp_qdio_set_data_div(qdio, &req->qdio_req,
+ zfcp_qdio_sbale_count(sg_req));
+ zfcp_qdio_set_sbale_last(qdio, &req->qdio_req);
+ zfcp_qdio_set_scount(qdio, &req->qdio_req);
return 0;
}

/* use single, unchained SBAL if it can hold the request */
if (zfcp_qdio_sg_one_sbale(sg_req) && zfcp_qdio_sg_one_sbale(sg_resp)) {
- zfcp_fsf_setup_ct_els_unchained(adapter->qdio, &req->qdio_req,
+ zfcp_fsf_setup_ct_els_unchained(qdio, &req->qdio_req,
sg_req, sg_resp);
return 0;
}

- bytes = zfcp_qdio_sbals_from_sg(adapter->qdio, &req->qdio_req, sg_req);
- if (bytes <= 0)
+ if (!(feat & FSF_FEATURE_ELS_CT_CHAINED_SBALS))
+ return -EOPNOTSUPP;
+
+ if (zfcp_qdio_sbals_from_sg(qdio, &req->qdio_req, sg_req))
return -EIO;
- zfcp_qdio_set_sbale_last(adapter->qdio, &req->qdio_req);
- req->qtcb->bottom.support.req_buf_length = bytes;
- zfcp_qdio_skip_to_last_sbale(&req->qdio_req);

- bytes = zfcp_qdio_sbals_from_sg(adapter->qdio, &req->qdio_req,
- sg_resp);
- req->qtcb->bottom.support.resp_buf_length = bytes;
- if (bytes <= 0)
+ qtcb->bottom.support.req_buf_length = zfcp_qdio_real_bytes(sg_req);
+
+ zfcp_qdio_set_sbale_last(qdio, &req->qdio_req);
+ zfcp_qdio_skip_to_last_sbale(qdio, &req->qdio_req);
+
+ if (zfcp_qdio_sbals_from_sg(qdio, &req->qdio_req, sg_resp))
return -EIO;
- zfcp_qdio_set_sbale_last(adapter->qdio, &req->qdio_req);
+
+ qtcb->bottom.support.resp_buf_length = zfcp_qdio_real_bytes(sg_resp);
+
+ zfcp_qdio_set_sbale_last(qdio, &req->qdio_req);

return 0;
}
@@ -1119,7 +1127,8 @@ int zfcp_fsf_send_els(struct zfcp_adapte

req->status |= ZFCP_STATUS_FSFREQ_CLEANUP;

- zfcp_qdio_sbal_limit(qdio, &req->qdio_req, 2);
+ if (!zfcp_adapter_multi_buffer_active(adapter))
+ zfcp_qdio_sbal_limit(qdio, &req->qdio_req, 2);

ret = zfcp_fsf_setup_ct_els(req, els->req, els->resp, timeout);

@@ -2162,7 +2171,7 @@ int zfcp_fsf_fcp_cmnd(struct scsi_cmnd *
struct zfcp_fsf_req *req;
struct fcp_cmnd *fcp_cmnd;
u8 sbtype = SBAL_SFLAGS0_TYPE_READ;
- int real_bytes, retval = -EIO, dix_bytes = 0;
+ int retval = -EIO;
struct scsi_device *sdev = scsi_cmnd->device;
struct zfcp_scsi_dev *zfcp_sdev = sdev_to_zfcp(sdev);
struct zfcp_adapter *adapter = zfcp_sdev->port->adapter;
@@ -2216,18 +2225,22 @@ int zfcp_fsf_fcp_cmnd(struct scsi_cmnd *
if (scsi_prot_sg_count(scsi_cmnd)) {
zfcp_qdio_set_data_div(qdio, &req->qdio_req,
scsi_prot_sg_count(scsi_cmnd));
- dix_bytes = zfcp_qdio_sbals_from_sg(qdio, &req->qdio_req,
+ retval = zfcp_qdio_sbals_from_sg(qdio, &req->qdio_req,
+ scsi_prot_sglist(scsi_cmnd));
+ if (retval)
+ goto failed_scsi_cmnd;
+ io->prot_data_length = zfcp_qdio_real_bytes(
scsi_prot_sglist(scsi_cmnd));
- io->prot_data_length = dix_bytes;
}

- real_bytes = zfcp_qdio_sbals_from_sg(qdio, &req->qdio_req,
- scsi_sglist(scsi_cmnd));
-
- if (unlikely(real_bytes < 0) || unlikely(dix_bytes < 0))
+ retval = zfcp_qdio_sbals_from_sg(qdio, &req->qdio_req,
+ scsi_sglist(scsi_cmnd));
+ if (unlikely(retval))
goto failed_scsi_cmnd;

zfcp_qdio_set_sbale_last(adapter->qdio, &req->qdio_req);
+ if (zfcp_adapter_multi_buffer_active(adapter))
+ zfcp_qdio_set_scount(qdio, &req->qdio_req);

retval = zfcp_fsf_req_send(req);
if (unlikely(retval))
@@ -2329,7 +2342,7 @@ struct zfcp_fsf_req *zfcp_fsf_control_fi
struct zfcp_qdio *qdio = adapter->qdio;
struct zfcp_fsf_req *req = NULL;
struct fsf_qtcb_bottom_support *bottom;
- int retval = -EIO, bytes;
+ int retval = -EIO;
u8 direction;

if (!(adapter->adapter_features & FSF_FEATURE_CFDC))
@@ -2362,13 +2375,17 @@ struct zfcp_fsf_req *zfcp_fsf_control_fi
bottom->operation_subtype = FSF_CFDC_OPERATION_SUBTYPE;
bottom->option = fsf_cfdc->option;

- bytes = zfcp_qdio_sbals_from_sg(qdio, &req->qdio_req, fsf_cfdc->sg);
+ retval = zfcp_qdio_sbals_from_sg(qdio, &req->qdio_req, fsf_cfdc->sg);

- if (bytes != ZFCP_CFDC_MAX_SIZE) {
+ if (retval ||
+ (zfcp_qdio_real_bytes(fsf_cfdc->sg) != ZFCP_CFDC_MAX_SIZE)) {
zfcp_fsf_req_free(req);
+ retval = -EIO;
goto out;
}
- zfcp_qdio_set_sbale_last(adapter->qdio, &req->qdio_req);
+ zfcp_qdio_set_sbale_last(qdio, &req->qdio_req);
+ if (zfcp_adapter_multi_buffer_active(adapter))
+ zfcp_qdio_set_scount(qdio, &req->qdio_req);

zfcp_fsf_start_timer(req, ZFCP_FSF_REQUEST_TIMEOUT);
retval = zfcp_fsf_req_send(req);
--- a/drivers/s390/scsi/zfcp_qdio.c
+++ b/drivers/s390/scsi/zfcp_qdio.c
@@ -15,6 +15,10 @@

#define QBUFF_PER_PAGE (PAGE_SIZE / sizeof(struct qdio_buffer))

+static bool enable_multibuffer;
+module_param_named(datarouter, enable_multibuffer, bool, 0400);
+MODULE_PARM_DESC(datarouter, "Enable hardware data router support");
+
static int zfcp_qdio_buffers_enqueue(struct qdio_buffer **sbal)
{
int pos;
@@ -37,8 +41,11 @@ static void zfcp_qdio_handler_error(stru

dev_warn(&adapter->ccw_device->dev, "A QDIO problem occurred\n");

- if (qdio_err & QDIO_ERROR_SLSB_STATE)
+ if (qdio_err & QDIO_ERROR_SLSB_STATE) {
zfcp_qdio_siosl(adapter);
+ zfcp_erp_adapter_shutdown(adapter, 0, id);
+ return;
+ }
zfcp_erp_adapter_reopen(adapter,
ZFCP_STATUS_ADAPTER_LINK_UNPLUGGED |
ZFCP_STATUS_COMMON_ERP_FAILED, id);
@@ -93,9 +100,27 @@ static void zfcp_qdio_int_resp(struct cc
unsigned long parm)
{
struct zfcp_qdio *qdio = (struct zfcp_qdio *) parm;
- int sbal_idx, sbal_no;
+ struct zfcp_adapter *adapter = qdio->adapter;
+ struct qdio_buffer_element *sbale;
+ int sbal_no, sbal_idx;
+ void *pl[ZFCP_QDIO_MAX_SBALS_PER_REQ + 1];
+ u64 req_id;
+ u8 scount;

if (unlikely(qdio_err)) {
+ memset(pl, 0, ZFCP_QDIO_MAX_SBALS_PER_REQ * sizeof(void *));
+ if (zfcp_adapter_multi_buffer_active(adapter)) {
+ sbale = qdio->res_q[idx]->element;
+ req_id = (u64) sbale->addr;
+ scount = sbale->scount + 1; /* incl. signaling SBAL */
+
+ for (sbal_no = 0; sbal_no < scount; sbal_no++) {
+ sbal_idx = (idx + sbal_no) %
+ QDIO_MAX_BUFFERS_PER_Q;
+ pl[sbal_no] = qdio->res_q[sbal_idx];
+ }
+ zfcp_dbf_hba_def_err(adapter, req_id, scount, pl);
+ }
zfcp_qdio_handler_error(qdio, "qdires1", qdio_err);
return;
}
@@ -155,7 +180,7 @@ zfcp_qdio_sbal_chain(struct zfcp_qdio *q
static struct qdio_buffer_element *
zfcp_qdio_sbale_next(struct zfcp_qdio *qdio, struct zfcp_qdio_req *q_req)
{
- if (q_req->sbale_curr == ZFCP_QDIO_LAST_SBALE_PER_SBAL)
+ if (q_req->sbale_curr == qdio->max_sbale_per_sbal - 1)
return zfcp_qdio_sbal_chain(qdio, q_req);
q_req->sbale_curr++;
return zfcp_qdio_sbale_curr(qdio, q_req);
@@ -167,13 +192,12 @@ zfcp_qdio_sbale_next(struct zfcp_qdio *q
* @q_req: pointer to struct zfcp_qdio_req
* @sg: scatter-gather list
* @max_sbals: upper bound for number of SBALs to be used
- * Returns: number of bytes, or error (negativ)
+ * Returns: zero or -EINVAL on error
*/
int zfcp_qdio_sbals_from_sg(struct zfcp_qdio *qdio, struct zfcp_qdio_req *q_req,
struct scatterlist *sg)
{
struct qdio_buffer_element *sbale;
- int bytes = 0;

/* set storage-block type for this request */
sbale = zfcp_qdio_sbale_req(qdio, q_req);
@@ -187,14 +211,10 @@ int zfcp_qdio_sbals_from_sg(struct zfcp_
q_req->sbal_number);
return -EINVAL;
}
-
sbale->addr = sg_virt(sg);
sbale->length = sg->length;
-
- bytes += sg->length;
}
-
- return bytes;
+ return 0;
}

static int zfcp_qdio_sbal_check(struct zfcp_qdio *qdio)
@@ -283,6 +303,8 @@ static void zfcp_qdio_setup_init_data(st
memcpy(id->adapter_name, dev_name(&id->cdev->dev), 8);
ASCEBC(id->adapter_name, 8);
id->qib_rflags = QIB_RFLAGS_ENABLE_DATA_DIV;
+ if (enable_multibuffer)
+ id->qdr_ac |= QDR_AC_MULTI_BUFFER_ENABLE;
id->no_input_qs = 1;
id->no_output_qs = 1;
id->input_handler = zfcp_qdio_int_resp;
@@ -378,6 +400,17 @@ int zfcp_qdio_open(struct zfcp_qdio *qdi
atomic_set_mask(ZFCP_STATUS_ADAPTER_DATA_DIV_ENABLED,
&qdio->adapter->status);

+ if (ssqd.qdioac2 & CHSC_AC2_MULTI_BUFFER_ENABLED) {
+ atomic_set_mask(ZFCP_STATUS_ADAPTER_MB_ACT, &adapter->status);
+ qdio->max_sbale_per_sbal = QDIO_MAX_ELEMENTS_PER_BUFFER;
+ } else {
+ atomic_clear_mask(ZFCP_STATUS_ADAPTER_MB_ACT, &adapter->status);
+ qdio->max_sbale_per_sbal = QDIO_MAX_ELEMENTS_PER_BUFFER - 1;
+ }
+
+ qdio->max_sbale_per_req =
+ ZFCP_QDIO_MAX_SBALS_PER_REQ * qdio->max_sbale_per_sbal
+ - 2;
if (qdio_activate(cdev))
goto failed_qdio;

@@ -397,6 +430,11 @@ int zfcp_qdio_open(struct zfcp_qdio *qdi
atomic_set(&qdio->req_q_free, QDIO_MAX_BUFFERS_PER_Q);
atomic_set_mask(ZFCP_STATUS_ADAPTER_QDIOUP, &qdio->adapter->status);

+ if (adapter->scsi_host) {
+ adapter->scsi_host->sg_tablesize = qdio->max_sbale_per_req;
+ adapter->scsi_host->max_sectors = qdio->max_sbale_per_req * 8;
+ }
+
return 0;

failed_qdio:
--- a/drivers/s390/scsi/zfcp_qdio.h
+++ b/drivers/s390/scsi/zfcp_qdio.h
@@ -13,20 +13,9 @@

#define ZFCP_QDIO_SBALE_LEN PAGE_SIZE

-/* DMQ bug workaround: don't use last SBALE */
-#define ZFCP_QDIO_MAX_SBALES_PER_SBAL (QDIO_MAX_ELEMENTS_PER_BUFFER - 1)
-
-/* index of last SBALE (with respect to DMQ bug workaround) */
-#define ZFCP_QDIO_LAST_SBALE_PER_SBAL (ZFCP_QDIO_MAX_SBALES_PER_SBAL - 1)
-
/* Max SBALS for chaining */
#define ZFCP_QDIO_MAX_SBALS_PER_REQ 36

-/* max. number of (data buffer) SBALEs in largest SBAL chain
- * request ID + QTCB in SBALE 0 + 1 of first SBAL in chain */
-#define ZFCP_QDIO_MAX_SBALES_PER_REQ \
- (ZFCP_QDIO_MAX_SBALS_PER_REQ * ZFCP_QDIO_MAX_SBALES_PER_SBAL - 2)
-
/**
* struct zfcp_qdio - basic qdio data structure
* @res_q: response queue
@@ -53,6 +42,8 @@ struct zfcp_qdio {
atomic_t req_q_full;
wait_queue_head_t req_q_wq;
struct zfcp_adapter *adapter;
+ u16 max_sbale_per_sbal;
+ u16 max_sbale_per_req;
};

/**
@@ -155,7 +146,7 @@ void zfcp_qdio_fill_next(struct zfcp_qdi
{
struct qdio_buffer_element *sbale;

- BUG_ON(q_req->sbale_curr == ZFCP_QDIO_LAST_SBALE_PER_SBAL);
+ BUG_ON(q_req->sbale_curr == qdio->max_sbale_per_sbal - 1);
q_req->sbale_curr++;
sbale = zfcp_qdio_sbale_curr(qdio, q_req);
sbale->addr = data;
@@ -195,9 +186,10 @@ int zfcp_qdio_sg_one_sbale(struct scatte
* @q_req: The current zfcp_qdio_req
*/
static inline
-void zfcp_qdio_skip_to_last_sbale(struct zfcp_qdio_req *q_req)
+void zfcp_qdio_skip_to_last_sbale(struct zfcp_qdio *qdio,
+ struct zfcp_qdio_req *q_req)
{
- q_req->sbale_curr = ZFCP_QDIO_LAST_SBALE_PER_SBAL;
+ q_req->sbale_curr = qdio->max_sbale_per_sbal - 1;
}

/**
@@ -228,8 +220,52 @@ void zfcp_qdio_set_data_div(struct zfcp_
{
struct qdio_buffer_element *sbale;

- sbale = &qdio->req_q[q_req->sbal_first]->element[0];
+ sbale = qdio->req_q[q_req->sbal_first]->element;
sbale->length = count;
}

+/**
+ * zfcp_qdio_sbale_count - count sbale used
+ * @sg: pointer to struct scatterlist
+ */
+static inline
+unsigned int zfcp_qdio_sbale_count(struct scatterlist *sg)
+{
+ unsigned int count = 0;
+
+ for (; sg; sg = sg_next(sg))
+ count++;
+
+ return count;
+}
+
+/**
+ * zfcp_qdio_real_bytes - count bytes used
+ * @sg: pointer to struct scatterlist
+ */
+static inline
+unsigned int zfcp_qdio_real_bytes(struct scatterlist *sg)
+{
+ unsigned int real_bytes = 0;
+
+ for (; sg; sg = sg_next(sg))
+ real_bytes += sg->length;
+
+ return real_bytes;
+}
+
+/**
+ * zfcp_qdio_set_scount - set SBAL count value
+ * @qdio: pointer to struct zfcp_qdio
+ * @q_req: The current zfcp_qdio_req
+ */
+static inline
+void zfcp_qdio_set_scount(struct zfcp_qdio *qdio, struct zfcp_qdio_req *q_req)
+{
+ struct qdio_buffer_element *sbale;
+
+ sbale = qdio->req_q[q_req->sbal_first]->element;
+ sbale->scount = q_req->sbal_number - 1;
+}
+
#endif /* ZFCP_QDIO_H */
--- a/drivers/s390/scsi/zfcp_scsi.c
+++ b/drivers/s390/scsi/zfcp_scsi.c
@@ -306,8 +306,8 @@ static struct scsi_host_template zfcp_sc
.proc_name = "zfcp",
.can_queue = 4096,
.this_id = -1,
- .sg_tablesize = ZFCP_QDIO_MAX_SBALES_PER_REQ,
- .max_sectors = (ZFCP_QDIO_MAX_SBALES_PER_REQ * 8),
+ .sg_tablesize = 1, /* adjusted later */
+ .max_sectors = 8, /* adjusted later */
.dma_boundary = ZFCP_QDIO_SBALE_LEN - 1,
.cmd_per_lun = 1,
.use_clustering = 1,
@@ -665,9 +665,9 @@ void zfcp_scsi_set_prot(struct zfcp_adap
adapter->adapter_features & FSF_FEATURE_DIX_PROT_TCPIP) {
mask |= SHOST_DIX_TYPE1_PROTECTION;
scsi_host_set_guard(shost, SHOST_DIX_GUARD_IP);
- shost->sg_prot_tablesize = ZFCP_QDIO_MAX_SBALES_PER_REQ / 2;
- shost->sg_tablesize = ZFCP_QDIO_MAX_SBALES_PER_REQ / 2;
- shost->max_sectors = ZFCP_QDIO_MAX_SBALES_PER_REQ * 8 / 2;
+ shost->sg_prot_tablesize = adapter->qdio->max_sbale_per_req / 2;
+ shost->sg_tablesize = adapter->qdio->max_sbale_per_req / 2;
+ shost->max_sectors = shost->sg_tablesize * 8;
}

scsi_host_set_prot(shost, mask);