virtio_blk: remove the broken zone revalidation support

virtblk_revalidate_zones is called unconditionally from
virtblk_config_changed_work from the virtio config_changed callback.

virtblk_revalidate_zones is a bit odd in that it re-clears the zoned
state for host aware or non-zoned devices, which isn't needed unless the
zoned mode changed - but a zone mode change to a host managed model isn't
handled at all, and virtio_blk also doesn't handle any other config
change except for a capacity change is handled (and even if it was
the upper layers above virtio_blk wouldn't handle it very well).

But even the useful case of a size change that would add or remove
zones isn't handled properly as blk_revalidate_disk_zones expects the
device capacity to cover all zones, but the capacity is only updated
after virtblk_revalidate_zones.

As this code appears to be entirely untested and is getting in the way
remove it for now, but it can be readded in a fixed version with
proper test coverage if needed.

Fixes: 95bfec41 ("virtio-blk: add support for zoned block devices")
Fixes: f1ba4e67 ("virtio-blk: fix to match virtio spec")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20231217165359.604246-3-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/virtio_blk.c

@@ -722,27 +722,6 @@ static int virtblk_report_zones(struct gendisk *disk, sector_t sector,
 	return ret;
 }
 
-static void virtblk_revalidate_zones(struct virtio_blk *vblk)
-{
-	u8 model;
-
-	virtio_cread(vblk->vdev, struct virtio_blk_config,
-		     zoned.model, &model);
-	switch (model) {
-	default:
-		dev_err(&vblk->vdev->dev, "unknown zone model %d\n", model);
-		fallthrough;
-	case VIRTIO_BLK_Z_NONE:
-	case VIRTIO_BLK_Z_HA:
-		disk_set_zoned(vblk->disk, BLK_ZONED_NONE);
-		return;
-	case VIRTIO_BLK_Z_HM:
-		WARN_ON_ONCE(!vblk->zone_sectors);
-		if (!blk_revalidate_disk_zones(vblk->disk, NULL))
-			set_capacity_and_notify(vblk->disk, 0);
-	}
-}
-
 static int virtblk_probe_zoned_device(struct virtio_device *vdev,
 				       struct virtio_blk *vblk,
 				       struct request_queue *q)
@@ -823,10 +802,6 @@ static int virtblk_probe_zoned_device(struct virtio_device *vdev,
  */
 #define virtblk_report_zones       NULL
 
-static inline void virtblk_revalidate_zones(struct virtio_blk *vblk)
-{
-}
-
 static inline int virtblk_probe_zoned_device(struct virtio_device *vdev,
 			struct virtio_blk *vblk, struct request_queue *q)
 {
@@ -982,7 +957,6 @@ static void virtblk_config_changed_work(struct work_struct *work)
 	struct virtio_blk *vblk =
 		container_of(work, struct virtio_blk, config_work);
 
-	virtblk_revalidate_zones(vblk);
 	virtblk_update_capacity(vblk, true);
 }