block: clarify context for refcount increment helpers

Let us clarify the context under which the helpers to increment the
refcount for the gendisk and request_queue can be called under. We
make this explicit on the places where we may sleep with might_sleep().

We don't address the decrement context yet, as that needs some extra
work and fixes, but will be addressed in the next patch.

Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-core.c

@@ -610,6 +610,8 @@ EXPORT_SYMBOL(blk_alloc_queue);
  * @q: the request_queue structure to increment the refcount for
  *
  * Increment the refcount of the request_queue kobject.
+ *
+ * Context: Any context.
  */
 bool blk_get_queue(struct request_queue *q)
 {

block/genhd.c

@@ -985,11 +985,15 @@ static ssize_t disk_badblocks_store(struct device *dev,
  *
  * This function gets the structure containing partitioning
  * information for the given device @devt.
+ *
+ * Context: can sleep
  */
 struct gendisk *get_gendisk(dev_t devt, int *partno)
 {
 	struct gendisk *disk = NULL;
 
+	might_sleep();
+
 	if (MAJOR(devt) != BLOCK_EXT_MAJOR) {
 		struct kobject *kobj;
 
@@ -1764,6 +1768,8 @@ EXPORT_SYMBOL(__alloc_disk_node);
  *
  * This increments the refcount for the struct gendisk, and the gendisk's
  * fops module owner.
+ *
+ * Context: Any context.
  */
 struct kobject *get_disk_and_module(struct gendisk *disk)
 {