block: add blk_alloc_disk and blk_cleanup_disk APIs

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>

1 files changed, 35 insertions, 0 deletions

diff --git a/block/genhd.c b/block/genhd.c
index c826db33a73e..efe0db4d62f0 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1293,6 +1293,25 @@ out_free_disk:
 }
 EXPORT_SYMBOL(__alloc_disk_node);
 
+struct gendisk *__blk_alloc_disk(int node)
+{
+	struct request_queue *q;
+	struct gendisk *disk;
+
+	q = blk_alloc_queue(node);
+	if (!q)
+		return NULL;
+
+	disk = __alloc_disk_node(0, node);
+	if (!disk) {
+		blk_cleanup_queue(q);
+		return NULL;
+	}
+	disk->queue = q;
+	return disk;
+}
+EXPORT_SYMBOL(__blk_alloc_disk);
+
 /**
  * put_disk - decrements the gendisk refcount
  * @disk: the struct gendisk to decrement the refcount for
@@ -1310,6 +1329,22 @@ void put_disk(struct gendisk *disk)
 }
 EXPORT_SYMBOL(put_disk);
 
+/**
+ * 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)
 {
 	char event[] = "DISK_RO=1";