s390/dasd/cio: Interpret ccw_device_get_mdc return value correctly
The max data count (mdc) is an unsigned 16-bit integer value as per AR documentation and is received via ccw_device_get_mdc() for a specific path mask from the CIO layer. The function itself also always returns a positive mdc value or 0 in case mdc isn't supported or couldn't be determined. Though, the comment for this function describes a negative return value to indicate failures. As a result, the DASD device driver interprets the return value of ccw_device_get_mdc() incorrectly. The error case is essentially a dead code path. To fix this behaviour, check explicitly for a return value of 0 and change the comment for ccw_device_get_mdc() accordingly. This fix merely enables the error code path in the DASD functions get_fcx_max_data() and verify_fcx_max_data(). The actual functionality stays the same and is still correct. Reviewed-by:Cornelia Huck <cohuck@redhat.com> Signed-off-by:
Jan Höppner <hoeppner@linux.ibm.com> Acked-by:
Peter Oberparleiter <oberpar@linux.ibm.com> Reviewed-by:
Stefan Haberland <sth@linux.ibm.com> Signed-off-by:
Stefan Haberland <sth@linux.ibm.com> Signed-off-by:
Jens Axboe <axboe@kernel.dk>
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