block: add SPDX tags to block layer files missing licensing information

Various block layer files do not have any licensing information at all.
Add SPDX tags for the default kernel GPLv2 license to those.
Reviewed-by: NChaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

block/blk-cgroup.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Common Block IO controller cgroup interface
  *

block/blk-core.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 1991, 1992 Linus Torvalds
  * Copyright (C) 1994,      Karl Keyte: Added support for disk statistics

block/blk-exec.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Functions related to setting various queue properties from drivers
  */

block/blk-iolatency.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Block rq-qos base io controller
  *

block/blk-mq-cpumap.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * CPU <-> hardware queue mapping helpers
  *

block/blk-mq-sched.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * blk-mq scheduling framework
  *

block/blk-mq-sysfs.c

+// SPDX-License-Identifier: GPL-2.0
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/backing-dev.h>

block/blk-mq-tag.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Tag allocation using scalable bitmaps. Uses active queue tracking to support
  * fairer distribution of tags between multiple submitters when a shared tag map

block/blk-mq.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Block multiqueue core code
  *

block/blk-rq-qos.c

+// SPDX-License-Identifier: GPL-2.0
+
 #include "blk-rq-qos.h"
 
 /*

block/blk-rq-qos.h

+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef RQ_QOS_H
 #define RQ_QOS_H
 

block/blk-settings.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Functions related to setting various queue properties from drivers
  */

block/blk-stat.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Block stat tracking code
  *

block/blk-timeout.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Functions related to generic timeout handling of requests.
  */

block/blk-wbt.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * buffered writeback throttling. loosely based on CoDel. We can't drop
  * packets for IO scheduling, so the logic is something like this:

block/blk-zoned.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Zoned block device handling
  *

block/elevator.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  *  Block device elevator/IO-scheduler.
  *

block/genhd.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  *  gendisk handling
  */

block/ioctl.c

+// SPDX-License-Identifier: GPL-2.0
 #include <linux/capability.h>
 #include <linux/blkdev.h>
 #include <linux/export.h>

block/ioprio.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * fs/ioprio.c
  *

block/mq-deadline.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  *  MQ Deadline i/o scheduler - adaptation of the legacy deadline scheduler,
  *  for the blk-mq scheduling framework

block/partitions/aix.h

+/* SPDX-License-Identifier: GPL-2.0 */
 extern int aix_partition(struct parsed_partitions *state);

block/partitions/amiga.h

+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  *  fs/partitions/amiga.h
  */

block/partitions/ibm.h

+/* SPDX-License-Identifier: GPL-2.0 */
 int ibm_partition(struct parsed_partitions *);

block/partitions/karma.h

+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  *  fs/partitions/karma.h
  */

block/partitions/msdos.h

+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  *  fs/partitions/msdos.h
  */

block/partitions/osf.h

+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  *  fs/partitions/osf.h
  */

block/partitions/sgi.h

+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  *  fs/partitions/sgi.h
  */

block/partitions/sun.h

+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  *  fs/partitions/sun.h
  */

block/partitions/sysv68.h

+/* SPDX-License-Identifier: GPL-2.0 */
 extern int sysv68_partition(struct parsed_partitions *state);

block/partitions/ultrix.h

+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  *  fs/partitions/ultrix.h
  */