idr: don't need to shink the free list when idr_remove()

After idr subsystem is changed to RCU-awared, the free layer will not go
to the free list.  The free list will not be filled up when
idr_remove().  So we don't need to shink it too.
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

lib/idr.c

@@ -18,12 +18,6 @@
  * pointer or what ever, we treat it as a (void *).  You can pass this
  * id to a user for him to pass back at a later time.  You then pass
  * that id to this code and it returns your pointer.
-
- * You can release ids at any time. When all ids are released, most of
- * the memory is returned (we keep MAX_IDR_FREE) in a local pool so we
- * don't need to go to the memory "store" during an id allocate, just
- * so you don't need to be too concerned about locking and conflicts
- * with the slab allocator.
  */
 
 #ifndef TEST                        // to test in user space...
@@ -584,16 +578,6 @@ void idr_remove(struct idr *idp, int id)
 		bitmap_clear(to_free->bitmap, 0, IDR_SIZE);
 		free_layer(idp, to_free);
 	}
-	while (idp->id_free_cnt >= MAX_IDR_FREE) {
-		p = get_from_free_list(idp);
-		/*
-		 * Note: we don't call the rcu callback here, since the only
-		 * layers that fall into the freelist are those that have been
-		 * preallocated.
-		 */
-		kmem_cache_free(idr_layer_cache, p);
-	}
-	return;
 }
 EXPORT_SYMBOL(idr_remove);