block: simplify printk_all_partitions

Just use xa_for_each to iterate over the partitions as there is no need
to grab a reference to each partition.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210406062303.811835-9-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/genhd.c

@@ -806,10 +806,10 @@ void __init printk_all_partitions(void)
 	class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
 	while ((dev = class_dev_iter_next(&iter))) {
 		struct gendisk *disk = dev_to_disk(dev);
-		struct disk_part_iter piter;
 		struct block_device *part;
 		char name_buf[BDEVNAME_SIZE];
 		char devt_buf[BDEVT_SIZE];
+		unsigned long idx;
 
 		/*
 		 * Don't show empty devices or things that have been
@@ -820,30 +820,29 @@ void __init printk_all_partitions(void)
 			continue;
 
 		/*
-		 * Note, unlike /proc/partitions, I am showing the
-		 * numbers in hex - the same format as the root=
-		 * option takes.
+		 * Note, unlike /proc/partitions, I am showing the numbers in
+		 * hex - the same format as the root= option takes.
 		 */
-		disk_part_iter_init(&piter, disk, DISK_PITER_INCL_PART0);
-		while ((part = disk_part_iter_next(&piter))) {
-			bool is_part0 = part == disk->part0;
-
-			printk("%s%s %10llu %s %s", is_part0 ? "" : "  ",
+		rcu_read_lock();
+		xa_for_each(&disk->part_tbl, idx, part) {
+			if (!bdev_nr_sectors(part))
+				continue;
+			printk("%s%s %10llu %s %s",
+			       bdev_is_partition(part) ? "  " : "",
 			       bdevt_str(part->bd_dev, devt_buf),
 			       bdev_nr_sectors(part) >> 1,
 			       disk_name(disk, part->bd_partno, name_buf),
 			       part->bd_meta_info ?
 					part->bd_meta_info->uuid : "");
-			if (is_part0) {
-				if (dev->parent && dev->parent->driver)
-					printk(" driver: %s\n",
-					      dev->parent->driver->name);
-				else
-					printk(" (driver?)\n");
-			} else
+			if (bdev_is_partition(part))
 				printk("\n");
+			else if (dev->parent && dev->parent->driver)
+				printk(" driver: %s\n",
+					dev->parent->driver->name);
+			else
+				printk(" (driver?)\n");
 		}
-		disk_part_iter_exit(&piter);
+		rcu_read_unlock();
 	}
 	class_dev_iter_exit(&iter);
 }