[S390] ccwreq: add ability to use all paths

Change the ccwrequest infrastructure to use more than one channel
path per start I/O. A flag "singlepath" is added to struct
ccw_request - if set, the old behavior is used. This flag is set
for all exploiters of the ccwrequest infrastructure - so there
is no functional change through this patch.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

4 files changed, 22 insertions, 7 deletions

diff --git a/drivers/s390/cio/ccwreq.c b/drivers/s390/cio/ccwreq.c
index fd0368785ee0..d15f8b4d78bd 100644
--- a/drivers/s390/cio/ccwreq.c
+++ b/drivers/s390/cio/ccwreq.c
@@ -38,9 +38,13 @@ static u16 ccwreq_next_path(struct ccw_device *cdev)
 {
         struct ccw_request *req = &cdev->private->req;
 
+        if (!req->singlepath) {
+                req->mask = 0;
+                goto out;
+        }
         req->retries    = req->maxretries;
         req->mask       = lpm_adjust(req->mask >>= 1, req->lpm);
-
+out:
         return req->mask;
 }
 
@@ -113,8 +117,12 @@ void ccw_request_start(struct ccw_device *cdev)
 {
         struct ccw_request *req = &cdev->private->req;
 
-        /* Try all paths twice to counter link flapping. */
-        req->mask       = 0x8080;
+        if (req->singlepath) {
+                /* Try all paths twice to counter link flapping. */
+                req->mask = 0x8080;
+        } else
+                req->mask = req->lpm;
+
         req->retries    = req->maxretries;
         req->mask       = lpm_adjust(req->mask, req->lpm);
         req->drc        = 0;
diff --git a/drivers/s390/cio/device_id.c b/drivers/s390/cio/device_id.c
index 78a0b43862c5..0d7fe4dab3b6 100644
--- a/drivers/s390/cio/device_id.c
+++ b/drivers/s390/cio/device_id.c
@@ -216,6 +216,7 @@ void ccw_device_sense_id_start(struct ccw_device *cdev)
         req->timeout    = SENSE_ID_TIMEOUT;
         req->maxretries = SENSE_ID_RETRIES;
         req->lpm        = sch->schib.pmcw.pam & sch->opm;
+        req->singlepath = 1;
         req->check      = snsid_check;
         req->callback   = snsid_callback;
         ccw_request_start(cdev);
diff --git a/drivers/s390/cio/device_pgid.c b/drivers/s390/cio/device_pgid.c
index 6facb5499a65..f1fdf0ec7f03 100644
--- a/drivers/s390/cio/device_pgid.c
+++ b/drivers/s390/cio/device_pgid.c
@@ -208,6 +208,7 @@ static void spid_start(struct ccw_device *cdev)
         req->timeout    = PGID_TIMEOUT;
         req->maxretries = PGID_RETRIES;
         req->lpm        = 0x80;
+        req->singlepath = 1;
         req->callback   = spid_callback;
         spid_do(cdev);
 }
@@ -420,6 +421,7 @@ static void verify_start(struct ccw_device *cdev)
         req->timeout    = PGID_TIMEOUT;
         req->maxretries = PGID_RETRIES;
         req->lpm        = 0x80;
+        req->singlepath = 1;
         if (cdev->private->flags.pgroup) {
                 CIO_TRACE_EVENT(4, "snid");
                 CIO_HEX_EVENT(4, devid, sizeof(*devid));
@@ -507,6 +509,7 @@ void ccw_device_disband_start(struct ccw_device *cdev)
         req->timeout    = PGID_TIMEOUT;
         req->maxretries = PGID_RETRIES;
         req->lpm        = sch->schib.pmcw.pam & sch->opm;
+        req->singlepath = 1;
         req->callback   = disband_callback;
         fn = SPID_FUNC_DISBAND;
         if (cdev->private->flags.mpath)
@@ -560,6 +563,7 @@ void ccw_device_stlck_start(struct ccw_device *cdev, void *data, void *buf1,
         req->timeout    = PGID_TIMEOUT;
         req->maxretries = PGID_RETRIES;
         req->lpm        = sch->schib.pmcw.pam & sch->opm;
+        req->singlepath = 1;
         req->data       = data;
         req->callback   = stlck_callback;
         stlck_build_cp(cdev, buf1, buf2);
diff --git a/drivers/s390/cio/io_sch.h b/drivers/s390/cio/io_sch.h
index b9ce712a7f25..469ef93f2302 100644
--- a/drivers/s390/cio/io_sch.h
+++ b/drivers/s390/cio/io_sch.h
@@ -92,11 +92,12 @@ enum io_status {
  * @filter: optional callback to adjust request status based on IRB data
  * @callback: final callback
  * @data: user-defined pointer passed to all callbacks
+ * @singlepath: if set, use only one path from @lpm per start I/O
+ * @cancel: non-zero if request was cancelled
+ * @done: non-zero if request was finished
  * @mask: current path mask
  * @retries: current number of retries
  * @drc: delayed return code
- * @cancel: non-zero if request was cancelled
- * @done: non-zero if request was finished
  */
 struct ccw_request {
         struct ccw1 *cp;
@@ -108,12 +109,13 @@ struct ccw_request {
                                  enum io_status);
         void (*callback)(struct ccw_device *, void *, int);
         void *data;
+        unsigned int singlepath:1;
         /* These fields are used internally. */
+        unsigned int cancel:1;
+        unsigned int done:1;
         u16 mask;
         u16 retries;
         int drc;
-        int cancel:1;
-        int done:1;
 } __attribute__((packed));
 
 /*