[S390] cio: improve error recovery for internal I/Os

Improve error recovery for internal I/Os by repeating each I/O
256 times per path to cope with long-running non-permanent error
conditions. Also retry each path twice to cope with link flapping,
i.e. single paths becoming unavailable in the order in which they
are tried.

Signed-off-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/drivers/s390/cio/ccwreq.c b/drivers/s390/cio/ccwreq.c
index a6e205a384b2..9509e3860934 100644
--- a/drivers/s390/cio/ccwreq.c
+++ b/drivers/s390/cio/ccwreq.c
@@ -82,7 +82,7 @@ static void ccwreq_do(struct ccw_device *cdev)
                 /* Perform start function. */
                 sch->lpm = 0xff;
                 memset(&cdev->private->irb, 0, sizeof(struct irb));
-                rc = cio_start(sch, cp, req->mask);
+                rc = cio_start(sch, cp, (u8) req->mask);
                 if (rc == 0) {
                         /* I/O started successfully. */
                         ccw_device_set_timeout(cdev, req->timeout);
@@ -116,7 +116,8 @@ void ccw_request_start(struct ccw_device *cdev)
 {
         struct ccw_request *req = &cdev->private->req;
 
-        req->mask       = 0x80;
+        /* Try all paths twice to counter link flapping. */
+        req->mask       = 0x8080;
         req->retries    = req->maxretries;
         req->mask       = lpm_adjust(req->mask, req->lpm);
         req->drc        = 0;
@@ -212,7 +213,7 @@ static void ccwreq_log_status(struct ccw_device *cdev, enum io_status status)
         }  __attribute__ ((packed)) data;
         data.dev_id     = cdev->private->dev_id;
         data.retries    = req->retries;
-        data.lpm        = req->mask;
+        data.lpm        = (u8) req->mask;
         data.status     = (u8) status;
         CIO_TRACE_EVENT(2, "reqstat");
         CIO_HEX_EVENT(2, &data, sizeof(data));