[PATCH v2 1/2] block: add blk_alloc_disk and blk_cleanup_disk APIs

[Valentin Kleibel <valentin@vrvis.at>]

Add two new APIs to allocate and free a gendisk including the
request_queue for use with BIO based drivers.  This is to avoid
boilerplate code in drivers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20210521055116.1053587-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(cherry picked from commit f525464a8000f092c20b00eead3eaa9d849c599e)
Fixes: 3582dd291788 (aoe: convert aoeblk to blk-mq)
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=215647
Signed-off-by: Valentin Kleibel <valentin@vrvis.at>
---
  block/genhd.c         | 15 +++++++++++++++
  include/linux/genhd.h |  1 +
  2 files changed, 16 insertions(+)

diff --git a/block/genhd.c b/block/genhd.c
index 796baf761202..421cad085502 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1836,6 +1836,21 @@ void put_disk_and_module(struct gendisk *disk)
         }
  }
  EXPORT_SYMBOL(put_disk_and_module);
+/**
+ * blk_cleanup_disk - shutdown a gendisk allocated by blk_alloc_disk
+ * @disk: gendisk to shutdown
+ *
+ * Mark the queue hanging off @disk DYING, drain all pending requests, 
then mark
+ * the queue DEAD, destroy and put it and the gendisk structure.
+ *
+ * Context: can sleep
+ */
+void blk_cleanup_disk(struct gendisk *disk)
+{
+       blk_cleanup_queue(disk->queue);
+       put_disk(disk);
+}
+EXPORT_SYMBOL(blk_cleanup_disk);

  static void set_disk_ro_uevent(struct gendisk *gd, int ro)
  {
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 03da3f603d30..b7b180d3734a 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -369,6 +369,7 @@ extern void blk_unregister_region(dev_t devt, 
unsigned long range);
  #define alloc_disk(minors) alloc_disk_node(minors, NUMA_NO_NODE)

  int register_blkdev(unsigned int major, const char *name);
+void blk_cleanup_disk(struct gendisk *disk);
  void unregister_blkdev(unsigned int major, const char *name);

  void revalidate_disk_size(struct gendisk *disk, bool verbose);