LU-3321 clio: revert LU-2622 for removing global env list

[fs/lustre-release.git] / lustre / obdclass / cl_object.c

diff --git a/lustre/obdclass/cl_object.c b/lustre/obdclass/cl_object.c
index a7236fc..8f29926 100644 (file)
--- a/lustre/obdclass/cl_object.c
+++ b/lustre/obdclass/cl_object.c
@@ -533,6 +533,12 @@ EXPORT_SYMBOL(cl_site_stats_print);
  * bz20044, bz22683.
  */
 
+static CFS_LIST_HEAD(cl_envs);
+static unsigned cl_envs_cached_nr  = 0;
+static unsigned cl_envs_cached_max = 128; /* XXX: prototype: arbitrary limit
+                                           * for now. */
+static DEFINE_SPINLOCK(cl_envs_guard);
+
 struct cl_env {
         void             *ce_magic;
         struct lu_env     ce_lu;
@@ -787,6 +793,40 @@ static void cl_env_fini(struct cl_env *cle)
         OBD_SLAB_FREE_PTR(cle, cl_env_kmem);
 }
 
+static struct lu_env *cl_env_obtain(void *debug)
+{
+       struct cl_env *cle;
+       struct lu_env *env;
+
+       ENTRY;
+       spin_lock(&cl_envs_guard);
+       LASSERT(equi(cl_envs_cached_nr == 0, cfs_list_empty(&cl_envs)));
+       if (cl_envs_cached_nr > 0) {
+               int rc;
+
+               cle = container_of(cl_envs.next, struct cl_env, ce_linkage);
+               cfs_list_del_init(&cle->ce_linkage);
+               cl_envs_cached_nr--;
+               spin_unlock(&cl_envs_guard);
+
+                env = &cle->ce_lu;
+                rc = lu_env_refill(env);
+                if (rc == 0) {
+                        cl_env_init0(cle, debug);
+                        lu_context_enter(&env->le_ctx);
+                        lu_context_enter(&cle->ce_ses);
+                } else {
+                        cl_env_fini(cle);
+                        env = ERR_PTR(rc);
+                }
+        } else {
+               spin_unlock(&cl_envs_guard);
+               env = cl_env_new(lu_context_tags_default,
+                                lu_session_tags_default, debug);
+       }
+       RETURN(env);
+}
+
 static inline struct cl_env *cl_env_container(struct lu_env *env)
 {
         return container_of(env, struct cl_env, ce_lu);
@@ -818,6 +858,8 @@ EXPORT_SYMBOL(cl_env_peek);
  * Returns lu_env: if there already is an environment associated with the
  * current thread, it is returned, otherwise, new environment is allocated.
  *
+ * Allocations are amortized through the global cache of environments.
+ *
  * \param refcheck pointer to a counter used to detect environment leaks. In
  * the usual case cl_env_get() and cl_env_put() are called in the same lexical
  * scope and pointer to the same integer is passed as \a refcheck. This is
@@ -831,10 +873,7 @@ struct lu_env *cl_env_get(int *refcheck)
 
         env = cl_env_peek(refcheck);
         if (env == NULL) {
-               env = cl_env_new(lu_context_tags_default,
-                                lu_session_tags_default,
-                                __builtin_return_address(0));
-
+                env = cl_env_obtain(__builtin_return_address(0));
                 if (!IS_ERR(env)) {
                         struct cl_env *cle;
 
@@ -878,6 +917,33 @@ static void cl_env_exit(struct cl_env *cle)
 }
 
 /**
+ * Finalizes and frees a given number of cached environments. This is done to
+ * (1) free some memory (not currently hooked into VM), or (2) release
+ * references to modules.
+ */
+unsigned cl_env_cache_purge(unsigned nr)
+{
+       struct cl_env *cle;
+
+       ENTRY;
+       spin_lock(&cl_envs_guard);
+       for (; !cfs_list_empty(&cl_envs) && nr > 0; --nr) {
+               cle = container_of(cl_envs.next, struct cl_env, ce_linkage);
+               cfs_list_del_init(&cle->ce_linkage);
+               LASSERT(cl_envs_cached_nr > 0);
+               cl_envs_cached_nr--;
+               spin_unlock(&cl_envs_guard);
+
+               cl_env_fini(cle);
+               spin_lock(&cl_envs_guard);
+       }
+       LASSERT(equi(cl_envs_cached_nr == 0, cfs_list_empty(&cl_envs)));
+       spin_unlock(&cl_envs_guard);
+       RETURN(nr);
+}
+EXPORT_SYMBOL(cl_env_cache_purge);
+
+/**
  * Release an environment.
  *
  * Decrement \a env reference counter. When counter drops to 0, nothing in
@@ -899,7 +965,21 @@ void cl_env_put(struct lu_env *env, int *refcheck)
                 cl_env_detach(cle);
                 cle->ce_debug = NULL;
                 cl_env_exit(cle);
-               cl_env_fini(cle);
+                /*
+                 * Don't bother to take a lock here.
+                 *
+                 * Return environment to the cache only when it was allocated
+                 * with the standard tags.
+                 */
+                if (cl_envs_cached_nr < cl_envs_cached_max &&
+                    (env->le_ctx.lc_tags & ~LCT_HAS_EXIT) == LCT_CL_THREAD &&
+                    (env->le_ses->lc_tags & ~LCT_HAS_EXIT) == LCT_SESSION) {
+                       spin_lock(&cl_envs_guard);
+                       cfs_list_add(&cle->ce_linkage, &cl_envs);
+                       cl_envs_cached_nr++;
+                       spin_unlock(&cl_envs_guard);
+               } else
+                       cl_env_fini(cle);
        }
 }
 EXPORT_SYMBOL(cl_env_put);