btrfs: add assertion helpers for spinning readers

Add helpers for conditional DEBUG build to assert that the extent buffer
spinning_readers constraints are met. Will be used in followup patches.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
David Sterba 2018-08-24 15:53:42 +02:00
commit 225948dedc