s390/dasd: fix failing CUIR assignment under LPAR

On LPAR the read message buffer command should be executed on the path
it was received on otherwise there is a chance that the CUIR assignment
might be faulty and the wrong channel path is set online/offline.

Fix by setting the path mask accordingly.
On z/VM we might not be able to do I/O on this path but there it does
not matter on which path the read message buffer command is executed.
Therefor implement a retry with an open path mask.

Signed-off-by: Stefan Haberland <sth@linux.vnet.ibm.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/s390/block/dasd_eckd.c b/drivers/s390/block/dasd_eckd.c
index fd2eff440098..98bbec44bcd0 100644
--- a/drivers/s390/block/dasd_eckd.c
+++ b/drivers/s390/block/dasd_eckd.c
@@ -5078,6 +5078,8 @@ static int dasd_eckd_read_message_buffer(struct dasd_device *device,
                 return PTR_ERR(cqr);
         }
 
+        cqr->lpm = lpum;
+retry:
         cqr->startdev = device;
         cqr->memdev = device;
         cqr->block = NULL;
@@ -5122,6 +5124,14 @@ static int dasd_eckd_read_message_buffer(struct dasd_device *device,
                         (prssdp + 1);
                 memcpy(messages, message_buf,
                        sizeof(struct dasd_rssd_messages));
+        } else if (cqr->lpm) {
+                /*
+                 * on z/VM we might not be able to do I/O on the requested path
+                 * but instead we get the required information on any path
+                 * so retry with open path mask
+                 */
+                cqr->lpm = 0;
+                goto retry;
         } else
                 DBF_EVENT_DEVID(DBF_WARNING, device->cdev,
                                 "Reading messages failed with rc=%d\n"