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    Subject[PATCH 06/20] staging: lustre: 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.

    Signed-off-by: NeilBrown <neilb@suse.com>
    ---
    drivers/staging/lustre/lustre/include/lustre_dlm.h | 2 ++
    drivers/staging/lustre/lustre/ldlm/ldlm_resource.c | 10 +++++-----
    2 files changed, 7 insertions(+), 5 deletions(-)

    diff --git a/drivers/staging/lustre/lustre/include/lustre_dlm.h b/drivers/staging/lustre/lustre/include/lustre_dlm.h
    index 395d50160dcc..ab90abe1c2d8 100644
    --- a/drivers/staging/lustre/lustre/include/lustre_dlm.h
    +++ b/drivers/staging/lustre/lustre/include/lustre_dlm.h
    @@ -309,6 +309,8 @@ struct ldlm_ns_bucket {
    * fact the network or overall system load is at fault
    */
    struct adaptive_timeout nsb_at_estimate;
    + /* counter of entries in this bucket */
    + atomic_t nsb_count;
    };

    enum {
    diff --git a/drivers/staging/lustre/lustre/ldlm/ldlm_resource.c b/drivers/staging/lustre/lustre/ldlm/ldlm_resource.c
    index 927544f01adc..669556420bdf 100644
    --- a/drivers/staging/lustre/lustre/ldlm/ldlm_resource.c
    +++ b/drivers/staging/lustre/lustre/ldlm/ldlm_resource.c
    @@ -181,12 +181,11 @@ 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 consistent */
    - 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);
    @@ -668,6 +667,7 @@ struct ldlm_namespace *ldlm_namespace_new(struct obd_device *obd, char *name,
    struct ldlm_ns_bucket *nsb = &ns->ns_rs_buckets[idx];
    at_init(&nsb->nsb_at_estimate, ldlm_enqueue_min, 0);
    nsb->nsb_namespace = ns;
    + atomic_set(&nsb->nsb_count, 0);
    }

    ns->ns_obd = obd;
    @@ -1144,7 +1144,7 @@ ldlm_resource_get(struct ldlm_namespace *ns, struct ldlm_resource *parent,
    }
    /* 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);
    @@ -1202,7 +1202,7 @@ static void __ldlm_resource_putref_final(struct cfs_hash_bd *bd,
    cfs_hash_bd_unlock(ns->ns_rs_hash, bd, 1);
    if (ns->ns_lvbo && ns->ns_lvbo->lvbo_free)
    ns->ns_lvbo->lvbo_free(res);
    - if (cfs_hash_bd_count_get(bd) == 0)
    + if (atomic_dec_and_test(&nsb->nsb_count))
    ldlm_namespace_put(ns);
    kmem_cache_free(ldlm_resource_slab, res);
    }

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