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Subject[patch 08/18] vmur: add "top of queue" sanity check for reader open
From: Michael Holzheu <holzheu@de.ibm.com>

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>
---
drivers/s390/char/vmur.c | 7 ++++++-
drivers/s390/char/vmur.h | 1 +
2 files changed, 7 insertions(+), 1 deletion(-)
Index: quilt-2.6/drivers/s390/char/vmur.c
===================================================================
--- quilt-2.6.orig/drivers/s390/char/vmur.c
+++ quilt-2.6/drivers/s390/char/vmur.c
@@ -565,9 +565,14 @@ static int verify_device(struct urdev *u
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;
Index: quilt-2.6/drivers/s390/char/vmur.h
===================================================================
--- quilt-2.6.orig/drivers/s390/char/vmur.h
+++ quilt-2.6/drivers/s390/char/vmur.h
@@ -53,6 +53,7 @@ struct file_control_block {
#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
--
blue skies,
Martin.

"Reality continues to ruin my life." - Calvin.

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