block: Remove zone write locking

Zone write locking is now unused and replaced with zone write plugging.
Remove all code that was implementing zone write locking, that is, the
various helper functions controlling request zone write locking and
the gendisk attached zone bitmaps.

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Tested-by: Hans Holmberg <hans.holmberg@wdc.com>
Tested-by: Dennis Maisenbacher <dennis.maisenbacher@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240408014128.205141-27-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

2 files changed, 3 insertions, 64 deletions

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index ca1f2b9422d5..770c0c2b72fa 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -256,7 +256,6 @@ static const char *const rqf_name[] = {
 	RQF_NAME(HASHED),
 	RQF_NAME(STATS),
 	RQF_NAME(SPECIAL_PAYLOAD),
-	RQF_NAME(ZONE_WRITE_LOCKED),
 	RQF_NAME(TIMED_OUT),
 	RQF_NAME(RESV),
 };
diff --git a/block/blk-zoned.c b/block/blk-zoned.c
index 44699b431ad0..3befebe6b319 100644
--- a/block/blk-zoned.c
+++ b/block/blk-zoned.c
@@ -115,52 +115,6 @@ const char *blk_zone_cond_str(enum blk_zone_cond zone_cond)
 }
 EXPORT_SYMBOL_GPL(blk_zone_cond_str);
 
-/*
- * Return true if a request is a write requests that needs zone write locking.
- */
-bool blk_req_needs_zone_write_lock(struct request *rq)
-{
-	if (!rq->q->disk->seq_zones_wlock)
-		return false;
-
-	return blk_rq_is_seq_zoned_write(rq);
-}
-EXPORT_SYMBOL_GPL(blk_req_needs_zone_write_lock);
-
-bool blk_req_zone_write_trylock(struct request *rq)
-{
-	unsigned int zno = blk_rq_zone_no(rq);
-
-	if (test_and_set_bit(zno, rq->q->disk->seq_zones_wlock))
-		return false;
-
-	WARN_ON_ONCE(rq->rq_flags & RQF_ZONE_WRITE_LOCKED);
-	rq->rq_flags |= RQF_ZONE_WRITE_LOCKED;
-
-	return true;
-}
-EXPORT_SYMBOL_GPL(blk_req_zone_write_trylock);
-
-void __blk_req_zone_write_lock(struct request *rq)
-{
-	if (WARN_ON_ONCE(test_and_set_bit(blk_rq_zone_no(rq),
-					  rq->q->disk->seq_zones_wlock)))
-		return;
-
-	WARN_ON_ONCE(rq->rq_flags & RQF_ZONE_WRITE_LOCKED);
-	rq->rq_flags |= RQF_ZONE_WRITE_LOCKED;
-}
-EXPORT_SYMBOL_GPL(__blk_req_zone_write_lock);
-
-void __blk_req_zone_write_unlock(struct request *rq)
-{
-	rq->rq_flags &= ~RQF_ZONE_WRITE_LOCKED;
-	if (rq->q->disk->seq_zones_wlock)
-		WARN_ON_ONCE(!test_and_clear_bit(blk_rq_zone_no(rq),
-						 rq->q->disk->seq_zones_wlock));
-}
-EXPORT_SYMBOL_GPL(__blk_req_zone_write_unlock);
-
 /**
  * bdev_nr_zones - Get number of zones
  * @bdev:	Target device
@@ -1506,9 +1460,6 @@ void disk_free_zone_resources(struct gendisk *disk)
 
 	kfree(disk->conv_zones_bitmap);
 	disk->conv_zones_bitmap = NULL;
-	kfree(disk->seq_zones_wlock);
-	disk->seq_zones_wlock = NULL;
-
 	disk->zone_capacity = 0;
 	disk->nr_zones = 0;
 }
@@ -1556,7 +1507,6 @@ static int disk_revalidate_zone_resources(struct gendisk *disk,
 struct blk_revalidate_zone_args {
 	struct gendisk	*disk;
 	unsigned long	*conv_zones_bitmap;
-	unsigned long	*seq_zones_wlock;
 	unsigned int	nr_zones;
 	unsigned int	zone_capacity;
 	sector_t	sector;
@@ -1574,7 +1524,6 @@ static int disk_update_zone_resources(struct gendisk *disk,
 
 	disk->nr_zones = args->nr_zones;
 	disk->zone_capacity = args->zone_capacity;
-	swap(disk->seq_zones_wlock, args->seq_zones_wlock);
 	swap(disk->conv_zones_bitmap, args->conv_zones_bitmap);
 
 	/*
@@ -1664,13 +1613,6 @@ static int blk_revalidate_zone_cb(struct blk_zone *zone, unsigned int idx,
 		set_bit(idx, args->conv_zones_bitmap);
 		break;
 	case BLK_ZONE_TYPE_SEQWRITE_REQ:
-		if (!args->seq_zones_wlock) {
-			args->seq_zones_wlock =
-				blk_alloc_zone_bitmap(q->node, args->nr_zones);
-			if (!args->seq_zones_wlock)
-				return -ENOMEM;
-		}
-
 		/*
 		 * Remember the capacity of the first sequential zone and check
 		 * if it is constant for all zones.
@@ -1712,7 +1654,7 @@ static int blk_revalidate_zone_cb(struct blk_zone *zone, unsigned int idx,
 }
 
 /**
- * blk_revalidate_disk_zones - (re)allocate and initialize zone bitmaps
+ * blk_revalidate_disk_zones - (re)allocate and initialize zone write plugs
  * @disk:	Target disk
  *
  * Helper function for low-level device drivers to check, (re) allocate and
@@ -1786,9 +1728,8 @@ int blk_revalidate_disk_zones(struct gendisk *disk)
 	}
 
 	/*
-	 * Install the new bitmaps and update nr_zones only once the queue is
-	 * stopped and all I/Os are completed (i.e. a scheduler is not
-	 * referencing the bitmaps).
+	 * Set the new disk zone parameters only once the queue is frozen and
+	 * all I/Os are completed.
 	 */
 	blk_mq_freeze_queue(q);
 	if (ret > 0)
@@ -1799,7 +1740,6 @@ int blk_revalidate_disk_zones(struct gendisk *disk)
 		disk_free_zone_resources(disk);
 	blk_mq_unfreeze_queue(q);
 
-	kfree(args.seq_zones_wlock);
 	kfree(args.conv_zones_bitmap);
 
 	return ret;