scsi: block: Remove RQF_PREEMPT and BLK_MQ_REQ_PREEMPT

Remove flag RQF_PREEMPT and BLK_MQ_REQ_PREEMPT since these are no longer
used by any kernel code.

Link: https://lore.kernel.org/r/[e-mail]
Cc: Can Guo <[e-mail]>
Cc: Stanley Chu <[e-mail]>
Cc: Alan Stern <[e-mail]>
Cc: Ming Lei <[e-mail]>
Cc: Rafael J. Wysocki <[e-mail]>
Cc: Martin Kepplinger <[e-mail]>
Reviewed-by: Christoph Hellwig <[e-mail]>
Reviewed-by: Hannes Reinecke <[e-mail]>
Reviewed-by: Jens Axboe <[e-mail]>
Reviewed-by: Can Guo <[e-mail]>
Signed-off-by: Bart Van Assche <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

block/blk-core.c

···
 /**
  * blk_queue_enter() - try to increase q->q_usage_counter
  * @q: request queue pointer
- * @flags: BLK_MQ_REQ_NOWAIT, BLK_MQ_REQ_PM and/or BLK_MQ_REQ_PREEMPT
+ * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PM
  */
 int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags)
 {
-	const bool pm = flags & (BLK_MQ_REQ_PM | BLK_MQ_REQ_PREEMPT);
+	const bool pm = flags & BLK_MQ_REQ_PM;
 
 	while (true) {
 		bool success = false;
···
 	struct request *req;
 
 	WARN_ON_ONCE(op & REQ_NOWAIT);
-	WARN_ON_ONCE(flags & ~(BLK_MQ_REQ_NOWAIT | BLK_MQ_REQ_PM |
-			       BLK_MQ_REQ_PREEMPT));
+	WARN_ON_ONCE(flags & ~(BLK_MQ_REQ_NOWAIT | BLK_MQ_REQ_PM));
 
 	req = blk_mq_alloc_request(q, op, flags);
 	if (!IS_ERR(req) && q->mq_ops->initialize_rq_fn)

block/blk-mq-debugfs.c

···
 	RQF_NAME(MIXED_MERGE),
 	RQF_NAME(MQ_INFLIGHT),
 	RQF_NAME(DONTPREP),
-	RQF_NAME(PREEMPT),
 	RQF_NAME(FAILED),
 	RQF_NAME(QUIET),
 	RQF_NAME(ELVPRIV),

block/blk-mq.c

···
 	rq->cmd_flags = data->cmd_flags;
 	if (data->flags & BLK_MQ_REQ_PM)
 		rq->rq_flags |= RQF_PM;
-	if (data->flags & BLK_MQ_REQ_PREEMPT)
-		rq->rq_flags |= RQF_PREEMPT;
 	if (blk_queue_io_stat(data->q))
 		rq->rq_flags |= RQF_IO_STAT;
 	INIT_LIST_HEAD(&rq->queuelist);

include/linux/blk-mq.h

···
 	BLK_MQ_REQ_RESERVED	= (__force blk_mq_req_flags_t)(1 << 1),
 	/* set RQF_PM */
 	BLK_MQ_REQ_PM		= (__force blk_mq_req_flags_t)(1 << 2),
-	/* set RQF_PREEMPT */
-	BLK_MQ_REQ_PREEMPT	= (__force blk_mq_req_flags_t)(1 << 3),
 };
 
 struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op,

include/linux/blkdev.h

···
 #define RQF_MQ_INFLIGHT		((__force req_flags_t)(1 << 6))
 /* don't call prep for this one */
 #define RQF_DONTPREP		((__force req_flags_t)(1 << 7))
-/* set for "ide_preempt" requests and also for requests for which the SCSI
-   "quiesce" state must be ignored. */
-#define RQF_PREEMPT		((__force req_flags_t)(1 << 8))
 /* vaguely specified driver internal error.  Ignored by the block layer */
 #define RQF_FAILED		((__force req_flags_t)(1 << 10))
 /* don't warn about errors */
···
 	unsigned long		queue_flags;
 	/*
 	 * Number of contexts that have called blk_set_pm_only(). If this
-	 * counter is above zero then only RQF_PM and RQF_PREEMPT requests are
-	 * processed.
+	 * counter is above zero then only RQF_PM requests are processed.
 	 */
 	atomic_t		pm_only;