[PATCH 17/20] staging: lustre: use call_rcu() to free lu_object_headers

[NeilBrown]

Using call_rcu to free lu_object_headers will allow us to use
rhashtable and get lockless lookup.

Signed-off-by: NeilBrown <ne...@suse.com>
---
 drivers/staging/lustre/lustre/include/lu_object.h  |    6 +++++-
 drivers/staging/lustre/lustre/llite/vvp_object.c   |    9 ++++++++-
 drivers/staging/lustre/lustre/lov/lovsub_object.c  |    9 ++++++++-
 .../staging/lustre/lustre/obdecho/echo_client.c    |    8 +++++++-
 4 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/lustre/lustre/include/lu_object.h 
b/drivers/staging/lustre/lustre/include/lu_object.h
index d23a78577fb5..85066ece44d6 100644
--- a/drivers/staging/lustre/lustre/include/lu_object.h
+++ b/drivers/staging/lustre/lustre/include/lu_object.h
@@ -535,8 +535,12 @@ struct lu_object_header {
        struct hlist_node       loh_hash;
        /**
         * Linkage into per-site LRU list. Protected by lu_site::ls_guard.
+        * memory shared with lru_head for delayed freeing;
         */
-       struct list_head             loh_lru;
+       union {
+               struct list_head        loh_lru;
+               struct rcu_head         loh_rcu;
+       };
        /**
         * Linkage into list of layers. Never modified once set (except lately
         * during object destruction). No locking is necessary.
diff --git a/drivers/staging/lustre/lustre/llite/vvp_object.c 
b/drivers/staging/lustre/lustre/llite/vvp_object.c
index 05ad3b322a29..48a999f8406b 100644
--- a/drivers/staging/lustre/lustre/llite/vvp_object.c
+++ b/drivers/staging/lustre/lustre/llite/vvp_object.c
@@ -251,13 +251,20 @@ static int vvp_object_init(const struct lu_env *env, 
struct lu_object *obj,
        return result;
 }
 
+static void __vvp_object_free(struct rcu_head *rcu)
+{
+       struct vvp_object *vob = container_of(rcu, struct vvp_object, 
vob_header.coh_lu.loh_rcu);
+
+       kmem_cache_free(vvp_object_kmem, vob);
+}
+
 static void vvp_object_free(const struct lu_env *env, struct lu_object *obj)
 {
        struct vvp_object *vob = lu2vvp(obj);
 
        lu_object_fini(obj);
        lu_object_header_fini(obj->lo_header);
-       kmem_cache_free(vvp_object_kmem, vob);
+       call_rcu(&vob->vob_header.coh_lu.loh_rcu, __vvp_object_free);
 }
 
 static const struct lu_object_operations vvp_lu_obj_ops = {
diff --git a/drivers/staging/lustre/lustre/lov/lovsub_object.c 
b/drivers/staging/lustre/lustre/lov/lovsub_object.c
index 13d452086b61..3626c2500149 100644
--- a/drivers/staging/lustre/lustre/lov/lovsub_object.c
+++ b/drivers/staging/lustre/lustre/lov/lovsub_object.c
@@ -70,6 +70,13 @@ int lovsub_object_init(const struct lu_env *env, struct 
lu_object *obj,
        return result;
 }
 
+static void __lovsub_object_free(struct rcu_head *rcu)
+{
+       struct lovsub_object *los = container_of(rcu, struct lovsub_object,
+                                                lso_header.coh_lu.loh_rcu);
+       kmem_cache_free(lovsub_object_kmem, los);
+}
+
 static void lovsub_object_free(const struct lu_env *env, struct lu_object *obj)
 {
        struct lovsub_object *los = lu2lovsub(obj);
@@ -88,7 +95,7 @@ static void lovsub_object_free(const struct lu_env *env, 
struct lu_object *obj)
 
        lu_object_fini(obj);
        lu_object_header_fini(&los->lso_header.coh_lu);
-       kmem_cache_free(lovsub_object_kmem, los);
+       call_rcu(&los->lso_header.coh_lu.loh_rcu, __lovsub_object_free);
 }
 
 static int lovsub_object_print(const struct lu_env *env, void *cookie,
diff --git a/drivers/staging/lustre/lustre/obdecho/echo_client.c 
b/drivers/staging/lustre/lustre/obdecho/echo_client.c
index 767067b61109..16bf3b5a74e4 100644
--- a/drivers/staging/lustre/lustre/obdecho/echo_client.c
+++ b/drivers/staging/lustre/lustre/obdecho/echo_client.c
@@ -431,6 +431,12 @@ static int echo_object_init(const struct lu_env *env, 
struct lu_object *obj,
        return 0;
 }
 
+static void __echo_object_free(struct rcu_head *rcu)
+{
+       struct echo_object *eco = container_of(rcu, struct echo_object, 
eo_hdr.coh_lu.loh_rcu);
+       kmem_cache_free(echo_object_kmem, eco);
+}
+
 static void echo_object_free(const struct lu_env *env, struct lu_object *obj)
 {
        struct echo_object *eco    = cl2echo_obj(lu2cl(obj));
@@ -446,7 +452,7 @@ static void echo_object_free(const struct lu_env *env, 
struct lu_object *obj)
        lu_object_header_fini(obj->lo_header);
 
        kfree(eco->eo_oinfo);
-       kmem_cache_free(echo_object_kmem, eco);
+       call_rcu(&eco->eo_hdr.coh_lu.loh_rcu, __echo_object_free);
 }
 
 static int echo_object_print(const struct lu_env *env, void *cookie,