Commit 4eac3452 authored by Michael Holzheu's avatar Michael Holzheu Committed by Martin Schwidefsky
Browse files

[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: default avatarMichael Holzheu <holzheu@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent f2405598
......@@ -565,9 +565,14 @@ static int verify_device(struct urdev *urd)
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;
......
......@@ -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
......
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