block: remove devnode callback from struct block_device_operations

With the removal of the pktcdvd driver, there are no in-kernel users of
the devnode callback in struct block_device_operations, so it can be
safely removed.  If it is needed for new block drivers in the future, it
can be brought back.

Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20221203140747.1942969-1-gregkh@linuxfoundation.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/genhd.c

@@ -1196,21 +1196,10 @@ struct class block_class = {
 	.dev_uevent	= block_uevent,
 };
 
-static char *block_devnode(struct device *dev, umode_t *mode,
-			   kuid_t *uid, kgid_t *gid)
-{
-	struct gendisk *disk = dev_to_disk(dev);
-
-	if (disk->fops->devnode)
-		return disk->fops->devnode(disk, mode);
-	return NULL;
-}
-
 const struct device_type disk_type = {
 	.name		= "disk",
 	.groups		= disk_attr_groups,
 	.release	= disk_release,
-	.devnode	= block_devnode,
 };
 
 #ifdef CONFIG_PROC_FS

include/linux/blkdev.h

@@ -1395,7 +1395,6 @@ struct block_device_operations {
 	void (*swap_slot_free_notify) (struct block_device *, unsigned long);
 	int (*report_zones)(struct gendisk *, sector_t sector,
 			unsigned int nr_zones, report_zones_cb cb, void *data);
-	char *(*devnode)(struct gendisk *disk, umode_t *mode);
 	/* returns the length of the identifier or a negative errno: */
 	int (*get_unique_id)(struct gendisk *disk, u8 id[16],
 			enum blk_unique_id id_type);