block: kill QUEUE_FLAG_FLUSH_NQ

We have various helpers for setting/clearing this flag, and also
a helper to check if the queue supports queueable flushes or not.
But nobody uses them anymore, kill it with fire.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-mq-debugfs.c

@@ -132,7 +132,6 @@ static const char *const blk_queue_flag_name[] = {
 	QUEUE_FLAG_NAME(POLL),
 	QUEUE_FLAG_NAME(WC),
 	QUEUE_FLAG_NAME(FUA),
-	QUEUE_FLAG_NAME(FLUSH_NQ),
 	QUEUE_FLAG_NAME(DAX),
 	QUEUE_FLAG_NAME(STATS),
 	QUEUE_FLAG_NAME(POLL_STATS),

block/blk-settings.c

@@ -799,15 +799,6 @@ void blk_queue_update_dma_alignment(struct request_queue *q, int mask)
 }
 EXPORT_SYMBOL(blk_queue_update_dma_alignment);
 
-void blk_queue_flush_queueable(struct request_queue *q, bool queueable)
-{
-	if (queueable)
-		blk_queue_flag_clear(QUEUE_FLAG_FLUSH_NQ, q);
-	else
-		blk_queue_flag_set(QUEUE_FLAG_FLUSH_NQ, q);
-}
-EXPORT_SYMBOL_GPL(blk_queue_flush_queueable);
-
 /**
  * blk_set_queue_depth - tell the block layer about the device queue depth
  * @q:		the request queue for the device

drivers/ata/libata-scsi.c

@@ -1318,8 +1318,6 @@ static int ata_scsi_dev_config(struct scsi_device *sdev,
 		scsi_change_queue_depth(sdev, depth);
 	}
 
-	blk_queue_flush_queueable(q, false);
-
 	if (dev->flags & ATA_DFLAG_TRUSTED)
 		sdev->security_supported = 1;
 

drivers/block/null_blk_main.c

@@ -1678,7 +1678,6 @@ static int null_add_dev(struct nullb_device *dev)
 	if (dev->cache_size > 0) {
 		set_bit(NULLB_DEV_FL_CACHE, &nullb->dev->flags);
 		blk_queue_write_cache(nullb->q, true, true);
-		blk_queue_flush_queueable(nullb->q, true);
 	}
 
 	if (dev->zoned) {

include/linux/blkdev.h

@@ -592,7 +592,6 @@ struct request_queue {
 #define QUEUE_FLAG_POLL	       19	/* IO polling enabled if set */
 #define QUEUE_FLAG_WC	       20	/* Write back caching */
 #define QUEUE_FLAG_FUA	       21	/* device supports FUA writes */
-#define QUEUE_FLAG_FLUSH_NQ    22	/* flush not queueuable */
 #define QUEUE_FLAG_DAX         23	/* device supports DAX */
 #define QUEUE_FLAG_STATS       24	/* track IO start and completion times */
 #define QUEUE_FLAG_POLL_STATS  25	/* collecting stats for hybrid polling */
@@ -1069,7 +1068,6 @@ extern void blk_queue_virt_boundary(struct request_queue *, unsigned long);
 extern void blk_queue_dma_alignment(struct request_queue *, int);
 extern void blk_queue_update_dma_alignment(struct request_queue *, int);
 extern void blk_queue_rq_timeout(struct request_queue *, unsigned int);
-extern void blk_queue_flush_queueable(struct request_queue *q, bool queueable);
 extern void blk_queue_write_cache(struct request_queue *q, bool enabled, bool fua);
 
 /*
@@ -1446,11 +1444,6 @@ static inline unsigned int block_size(struct block_device *bdev)
 	return bdev->bd_block_size;
 }
 
-static inline bool queue_flush_queueable(struct request_queue *q)
-{
-	return !test_bit(QUEUE_FLAG_FLUSH_NQ, &q->queue_flags);
-}
-
 typedef struct {struct page *v;} Sector;
 
 unsigned char *read_dev_sector(struct block_device *, sector_t, Sector *);