[S390] vmur: add "top of queue" sanity check for reader open
If the z/VM reader is already open, it can happen that after opening the
Linux reader device, not the topmost file is processed. According the
semantics of the Linux z/VM unit record device driver, always the topmost
file has to be processed. With this fix an error is returned if that is
not the case.
Signed-off-by: Michael Holzheu <holzheu@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/char/vmur.c b/drivers/s390/char/vmur.c
index 04395c0..a9d5862 100644
--- a/drivers/s390/char/vmur.c
+++ b/drivers/s390/char/vmur.c
@@ -565,9 +565,14 @@
return -ENOMEM;
rc = diag_read_file(urd->dev_id.devno, buf);
kfree(buf);
-
if ((rc != 0) && (rc != -ENODATA)) /* EOF does not hurt */
return rc;
+ /* check if the file on top of the queue is open now */
+ rc = diag_read_next_file_info(&fcb, 0);
+ if (rc)
+ return rc;
+ if (!(fcb.file_stat & FLG_IN_USE))
+ return -EMFILE;
return 0;
default:
return -ENOTSUPP;
diff --git a/drivers/s390/char/vmur.h b/drivers/s390/char/vmur.h
index 522a9df..2b3c564 100644
--- a/drivers/s390/char/vmur.h
+++ b/drivers/s390/char/vmur.h
@@ -53,6 +53,7 @@
#define FLG_SYSTEM_HOLD 0x04
#define FLG_CP_DUMP 0x10
#define FLG_USER_HOLD 0x20
+#define FLG_IN_USE 0x80
/*
* A struct urdev is created for each ur device that is made available