ceph: mark the cap cache as unreclaimable

Releasing cap is affected by many factors (e.g., avail_count/reserve_count/min_count)
and min_count could be specified high volume in client mount option. Hence it's better
to mark cap cache as unreclaimable in case of non-trivial discrepancies between memory
shown as reclaimable and what is actually reclaimed.
Signed-off-by: NChengguang Xu <cgxu519@icloud.com>
Reviewed-by: N"Yan, Zheng" <zyan@redhat.com>
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>

fs/ceph/super.c

@@ -698,8 +698,7 @@ static int __init init_caches(void)
 	if (!ceph_inode_cachep)
 		return -ENOMEM;
 
-	ceph_cap_cachep = KMEM_CACHE(ceph_cap,
-				     SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD);
+	ceph_cap_cachep = KMEM_CACHE(ceph_cap, SLAB_MEM_SPREAD);
 	if (!ceph_cap_cachep)
 		goto bad_cap;
 	ceph_cap_flush_cachep = KMEM_CACHE(ceph_cap_flush,