LU-8130 ldlm: add a counter to the per-namespace data

When we change the resource hash to rhashtable we won't have
a per-bucket counter.  We could use the nelems global counter,
but ldlm_resource goes to some trouble to avoid having any
table-wide atomics, and hopefully rhashtable will grow the
ability to disable the global counter in the near future.
Having a counter we control makes it easier to manage the
back-reference to the namespace when there is anything in the
hash table.

So add a counter to the ldlm_ns_bucket.

Change-Id: Ic79e96f95d5cacfb5e7bb02350f5f4fafb207b44
Signed-off-by: NeilBrown <neilb@suse.com>
Reviewed-on: https://review.whamcloud.com/36219
Reviewed-by: Neil Brown <neilb@suse.de>
Reviewed-by: Shaun Tancheff <stancheff@cray.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>

diff --git a/lustre/include/lustre_dlm.h b/lustre/include/lustre_dlm.h
index c3a7928..4f285f8 100644 (file)
--- a/lustre/include/lustre_dlm.h
+++ b/lustre/include/lustre_dlm.h
@@ -333,6 +333,8 @@ struct ldlm_ns_bucket {
         * Which res in the bucket should we start with the reclaim.
         */
        int                         nsb_reclaim_start;
+       /* counter of entries in this bucket */
+       atomic_t                nsb_count;
 };
 
 enum {

diff --git a/lustre/ldlm/ldlm_resource.c b/lustre/ldlm/ldlm_resource.c
index a65a75c..d5f93fd 100644 (file)
--- a/lustre/ldlm/ldlm_resource.c
+++ b/lustre/ldlm/ldlm_resource.c
@@ -285,12 +285,11 @@ static ssize_t resource_count_show(struct kobject *kobj, struct attribute *attr,
        struct ldlm_namespace *ns = container_of(kobj, struct ldlm_namespace,
                                                 ns_kobj);
        __u64                   res = 0;
-       struct cfs_hash_bd              bd;
        int                     i;
 
        /* result is not strictly consistant */
-       cfs_hash_for_each_bucket(ns->ns_rs_hash, &bd, i)
-               res += cfs_hash_bd_count_get(&bd);
+       for (i = 0; i < (1 << ns->ns_bucket_bits); i++)
+               res += atomic_read(&ns->ns_rs_buckets[i].nsb_count);
        return sprintf(buf, "%lld\n", res);
 }
 LUSTRE_RO_ATTR(resource_count);
@@ -942,6 +941,7 @@ struct ldlm_namespace *ldlm_namespace_new(struct obd_device *obd, char *name,
                at_init(&nsb->nsb_at_estimate, ldlm_enqueue_min, 0);
                nsb->nsb_namespace = ns;
                nsb->nsb_reclaim_start = 0;
+               atomic_set(&nsb->nsb_count, 0);
        }
 
        ns->ns_obd = obd;
@@ -1530,7 +1530,7 @@ found:
        }
        /* We won! Let's add the resource. */
        cfs_hash_bd_add_locked(ns->ns_rs_hash, &bd, &res->lr_hash);
-       if (cfs_hash_bd_count_get(&bd) == 1)
+       if (atomic_inc_return(&res->lr_ns_bucket->nsb_count) == 1)
                ns_refcount = ldlm_namespace_get_return(ns);
 
        cfs_hash_bd_unlock(ns->ns_rs_hash, &bd, 1);
@@ -1579,7 +1579,7 @@ static void __ldlm_resource_putref_final(struct cfs_hash_bd *bd,
        cfs_hash_bd_del_locked(nsb->nsb_namespace->ns_rs_hash,
                               bd, &res->lr_hash);
        lu_ref_fini(&res->lr_reference);
-       if (cfs_hash_bd_count_get(bd) == 0)
+       if (atomic_dec_and_test(&nsb->nsb_count))
                ldlm_namespace_put(nsb->nsb_namespace);
 }