+/* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
+ * vim:expandtab:shiftwidth=8:tabstop=8:
+ *
+ * GPL HEADER START
+ *
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 only,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License version 2 for more details (a copy is included
+ * in the LICENSE file that accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License
+ * version 2 along with this program; If not, see
+ * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ * GPL HEADER END
+ */
+/*
+ * Copyright 2008 Sun Microsystems, Inc. All rights reserved.
+ * Use is subject to license terms.
+ */
+/*
+ * This file is part of Lustre, http://www.lustre.org/
+ * Lustre is a trademark of Sun Microsystems, Inc.
+ *
+ * lustre/obdclass/lu_ref.c
+ *
+ * Lustre reference.
+ *
+ * Author: Nikita Danilov <nikita.danilov@sun.com>
+ */
+
+#define DEBUG_SUBSYSTEM S_CLASS
+#ifndef EXPORT_SYMTAB
+# define EXPORT_SYMTAB
+#endif
+
+#ifdef __KERNEL__
+# include <libcfs/libcfs.h>
+#else
+# include <liblustre.h>
+#endif
+
+#include <obd.h>
+#include <obd_class.h>
+#include <obd_support.h>
+#include <lu_ref.h>
+
+#ifdef USE_LU_REF
+
+struct lu_ref_link {
+ struct lu_ref *ll_ref;
+ struct list_head ll_linkage;
+ const char *ll_scope;
+ const void *ll_source;
+};
+
+static cfs_mem_cache_t *lu_ref_link_kmem;
+
+static struct lu_kmem_descr lu_ref_caches[] = {
+ {
+ .ckd_cache = &lu_ref_link_kmem,
+ .ckd_name = "lu_ref_link_kmem",
+ .ckd_size = sizeof (struct lu_ref_link)
+ },
+ {
+ .ckd_cache = NULL
+ }
+};
+
+void lu_ref_print(const struct lu_ref *ref)
+{
+ struct lu_ref_link *link;
+
+ CERROR("lu_ref: %p %d\n", ref, ref->lf_failed);
+ list_for_each_entry(link, &ref->lf_list, ll_linkage) {
+ CERROR(" link: %s %p\n", link->ll_scope, link->ll_source);
+ }
+}
+EXPORT_SYMBOL(lu_ref_print);
+
+void lu_ref_init(struct lu_ref *ref)
+{
+ spin_lock_init(&ref->lf_guard);
+ CFS_INIT_LIST_HEAD(&ref->lf_list);
+}
+EXPORT_SYMBOL(lu_ref_init);
+
+void lu_ref_fini(struct lu_ref *ref)
+{
+ if (!list_empty(&ref->lf_list)) {
+ spin_lock(&ref->lf_guard);
+ lu_ref_print(ref);
+ spin_unlock(&ref->lf_guard);
+ }
+ LASSERT(list_empty(&ref->lf_list));
+}
+EXPORT_SYMBOL(lu_ref_fini);
+int lu_ref_global_init(void);
+
+static struct lu_ref_link *lu_ref_add_context(struct lu_ref *ref,
+ enum cfs_alloc_flags flags,
+ const char *scope,
+ const void *source)
+{
+ struct lu_ref_link *link;
+
+ /* this can be called so early in lustre initialization, that
+ * lu_ref_link_kmem slab is not yet created. */
+ lu_ref_global_init();
+
+ link = NULL;
+ if (lu_ref_link_kmem != NULL) {
+ OBD_SLAB_ALLOC(link, lu_ref_link_kmem, flags, sizeof(*link));
+ if (link != NULL) {
+ link->ll_ref = ref;
+ link->ll_scope = scope;
+ link->ll_source = source;
+ spin_lock(&ref->lf_guard);
+ list_add_tail(&link->ll_linkage, &ref->lf_list);
+ spin_unlock(&ref->lf_guard);
+ }
+ }
+
+ if (link == NULL) {
+ spin_lock(&ref->lf_guard);
+ ref->lf_failed++;
+ spin_unlock(&ref->lf_guard);
+ link = ERR_PTR(-ENOMEM);
+ }
+ return link;
+}
+
+struct lu_ref_link *lu_ref_add(struct lu_ref *ref, const char *scope,
+ const void *source)
+{
+ might_sleep();
+ return lu_ref_add_context(ref, CFS_ALLOC_STD, scope, source);
+}
+EXPORT_SYMBOL(lu_ref_add);
+
+/**
+ * Version of lu_ref_add() to be used in non-blockable contexts.
+ */
+struct lu_ref_link *lu_ref_add_atomic(struct lu_ref *ref, const char *scope,
+ const void *source)
+{
+ return lu_ref_add_context(ref, CFS_ALLOC_ATOMIC, scope, source);
+}
+EXPORT_SYMBOL(lu_ref_add_atomic);
+
+static inline int lu_ref_link_eq(const struct lu_ref_link *link,
+ const char *scope, const void *source)
+{
+ return link->ll_source == source && !strcmp(link->ll_scope, scope);
+}
+
+/**
+ * Maximal chain length seen so far.
+ */
+static unsigned lu_ref_chain_max_length = 127;
+
+/**
+ * Searches for a lu_ref_link with given [scope, source] within given lu_ref.
+ */
+static struct lu_ref_link *lu_ref_find(struct lu_ref *ref, const char *scope,
+ const void *source)
+{
+ struct lu_ref_link *link;
+ unsigned iterations;
+
+ iterations = 0;
+ list_for_each_entry(link, &ref->lf_list, ll_linkage) {
+ ++iterations;
+ if (lu_ref_link_eq(link, scope, source)) {
+ if (iterations > lu_ref_chain_max_length) {
+ CWARN("Long lu_ref chain %i \"%s\":%p\n",
+ iterations, scope, source);
+ lu_ref_chain_max_length = iterations * 3 / 2;
+ }
+ return link;
+ }
+ }
+ return NULL;
+}
+
+void lu_ref_del(struct lu_ref *ref, const char *scope, const void *source)
+{
+ struct lu_ref_link *link;
+
+ spin_lock(&ref->lf_guard);
+ link = lu_ref_find(ref, scope, source);
+ if (link != NULL) {
+ list_del(&link->ll_linkage);
+ spin_unlock(&ref->lf_guard);
+ OBD_SLAB_FREE(link, lu_ref_link_kmem, sizeof(*link));
+ } else {
+ LASSERT(ref->lf_failed > 0);
+ ref->lf_failed--;
+ spin_unlock(&ref->lf_guard);
+ }
+}
+EXPORT_SYMBOL(lu_ref_del);
+
+void lu_ref_set_at(struct lu_ref *ref, struct lu_ref_link *link,
+ const char *scope,
+ const void *source0, const void *source1)
+{
+ spin_lock(&ref->lf_guard);
+ if (link != ERR_PTR(-ENOMEM)) {
+ LASSERT(link->ll_ref == ref);
+ LASSERT(lu_ref_link_eq(link, scope, source0));
+ link->ll_source = source1;
+ } else {
+ LASSERT(ref->lf_failed > 0);
+ }
+ spin_unlock(&ref->lf_guard);
+}
+EXPORT_SYMBOL(lu_ref_set_at);
+
+void lu_ref_del_at(struct lu_ref *ref, struct lu_ref_link *link,
+ const char *scope, const void *source)
+{
+ if (link != ERR_PTR(-ENOMEM)) {
+ LASSERT(link->ll_ref == ref);
+ LASSERT(lu_ref_link_eq(link, scope, source));
+ spin_lock(&ref->lf_guard);
+ list_del(&link->ll_linkage);
+ spin_unlock(&ref->lf_guard);
+ OBD_SLAB_FREE(link, lu_ref_link_kmem, sizeof(*link));
+ } else {
+ LASSERT(ref->lf_failed > 0);
+ spin_lock(&ref->lf_guard);
+ ref->lf_failed--;
+ spin_unlock(&ref->lf_guard);
+ }
+}
+EXPORT_SYMBOL(lu_ref_del_at);
+
+static int lu_ref_initialized = 0;
+int lu_ref_global_init(void)
+{
+ int result;
+
+ if (lu_ref_initialized == 0) {
+ lu_ref_initialized = 1;
+ CDEBUG(D_CONSOLE,
+ "lu_ref tracking is enabled. Performance isn't.\n");
+ result = lu_kmem_init(lu_ref_caches);
+ } else
+ result = 0;
+ return result;
+}
+
+void lu_ref_global_fini(void)
+{
+ lu_kmem_fini(lu_ref_caches);
+}
+
+#endif /* USE_LU_REF */