In preparation for implementing lockless slab shrink,
we need to dynamically allocate the md-bcache shrinker,
so that it can be freed asynchronously using kfree_rcu().
Then it doesn't need to wait for RCU read-side critical
section when releasing the struct cache_set.
Signed-off-by: Qi Zheng
---
From: Qi Zheng
In preparation for implementing lockless slab shrink,
we need to dynamically allocate the md-bcache shrinker,
so that it can be freed asynchronously using kfree_rcu().
Then it doesn't need to wait for RCU read-side critical
section when releasing the struct cache_set.
Signed-off-b
