block: allow initialization of previously allocated request_queue
blk_init_queue() allocates the request_queue structure and then
initializes it as needed (request_fn, elevator, etc).
Split initialization out to blk_init_allocated_queue_node.
Introduce blk_init_allocated_queue wrapper function to model existing
blk_init_queue and blk_init_queue_node interfaces.
Export elv_register_queue to allow a newly added elevator to be
registered with sysfs. Export elv_unregister_queue for symmetry.
These changes allow DM to initialize a device's request_queue with more
precision. In particular, DM no longer unconditionally initializes a
full request_queue (elevator et al). It only does so for a
request-based DM device.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/block/elevator.c b/block/elevator.c
index 5e73459..6df2b50 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -930,6 +930,7 @@
}
return error;
}
+EXPORT_SYMBOL(elv_register_queue);
static void __elv_unregister_queue(struct elevator_queue *e)
{
@@ -942,6 +943,7 @@
if (q)
__elv_unregister_queue(q->elevator);
}
+EXPORT_SYMBOL(elv_unregister_queue);
void elv_register(struct elevator_type *e)
{