[PATCH] configfs: User-driven configuration filesystem
Configfs, a file system for userspace-driven kernel object configuration.
The OCFS2 stack makes extensive use of this for propagation of cluster
configuration information into kernel.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
diff --git a/fs/configfs/item.c b/fs/configfs/item.c
new file mode 100644
index 0000000..e07485a
--- /dev/null
+++ b/fs/configfs/item.c
@@ -0,0 +1,227 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * item.c - library routines for handling generic config items
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * 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 for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ *
+ * Based on kobject:
+ * kobject is Copyright (c) 2002-2003 Patrick Mochel
+ *
+ * configfs Copyright (C) 2005 Oracle. All rights reserved.
+ *
+ * Please see the file Documentation/filesystems/configfs.txt for
+ * critical information about using the config_item interface.
+ */
+
+#include <linux/string.h>
+#include <linux/module.h>
+#include <linux/stat.h>
+#include <linux/slab.h>
+
+#include <linux/configfs.h>
+
+
+static inline struct config_item * to_item(struct list_head * entry)
+{
+ return container_of(entry,struct config_item,ci_entry);
+}
+
+/* Evil kernel */
+static void config_item_release(struct kref *kref);
+
+/**
+ * config_item_init - initialize item.
+ * @item: item in question.
+ */
+void config_item_init(struct config_item * item)
+{
+ kref_init(&item->ci_kref);
+ INIT_LIST_HEAD(&item->ci_entry);
+}
+
+/**
+ * config_item_set_name - Set the name of an item
+ * @item: item.
+ * @name: name.
+ *
+ * If strlen(name) >= CONFIGFS_ITEM_NAME_LEN, then use a
+ * dynamically allocated string that @item->ci_name points to.
+ * Otherwise, use the static @item->ci_namebuf array.
+ */
+
+int config_item_set_name(struct config_item * item, const char * fmt, ...)
+{
+ int error = 0;
+ int limit = CONFIGFS_ITEM_NAME_LEN;
+ int need;
+ va_list args;
+ char * name;
+
+ /*
+ * First, try the static array
+ */
+ va_start(args,fmt);
+ need = vsnprintf(item->ci_namebuf,limit,fmt,args);
+ va_end(args);
+ if (need < limit)
+ name = item->ci_namebuf;
+ else {
+ /*
+ * Need more space? Allocate it and try again
+ */
+ limit = need + 1;
+ name = kmalloc(limit,GFP_KERNEL);
+ if (!name) {
+ error = -ENOMEM;
+ goto Done;
+ }
+ va_start(args,fmt);
+ need = vsnprintf(name,limit,fmt,args);
+ va_end(args);
+
+ /* Still? Give up. */
+ if (need >= limit) {
+ kfree(name);
+ error = -EFAULT;
+ goto Done;
+ }
+ }
+
+ /* Free the old name, if necessary. */
+ if (item->ci_name && item->ci_name != item->ci_namebuf)
+ kfree(item->ci_name);
+
+ /* Now, set the new name */
+ item->ci_name = name;
+ Done:
+ return error;
+}
+
+EXPORT_SYMBOL(config_item_set_name);
+
+void config_item_init_type_name(struct config_item *item,
+ const char *name,
+ struct config_item_type *type)
+{
+ config_item_set_name(item, name);
+ item->ci_type = type;
+ config_item_init(item);
+}
+EXPORT_SYMBOL(config_item_init_type_name);
+
+void config_group_init_type_name(struct config_group *group, const char *name,
+ struct config_item_type *type)
+{
+ config_item_set_name(&group->cg_item, name);
+ group->cg_item.ci_type = type;
+ config_group_init(group);
+}
+EXPORT_SYMBOL(config_group_init_type_name);
+
+struct config_item * config_item_get(struct config_item * item)
+{
+ if (item)
+ kref_get(&item->ci_kref);
+ return item;
+}
+
+/**
+ * config_item_cleanup - free config_item resources.
+ * @item: item.
+ */
+
+void config_item_cleanup(struct config_item * item)
+{
+ struct config_item_type * t = item->ci_type;
+ struct config_group * s = item->ci_group;
+ struct config_item * parent = item->ci_parent;
+
+ pr_debug("config_item %s: cleaning up\n",config_item_name(item));
+ if (item->ci_name != item->ci_namebuf)
+ kfree(item->ci_name);
+ item->ci_name = NULL;
+ if (t && t->ct_item_ops && t->ct_item_ops->release)
+ t->ct_item_ops->release(item);
+ if (s)
+ config_group_put(s);
+ if (parent)
+ config_item_put(parent);
+}
+
+static void config_item_release(struct kref *kref)
+{
+ config_item_cleanup(container_of(kref, struct config_item, ci_kref));
+}
+
+/**
+ * config_item_put - decrement refcount for item.
+ * @item: item.
+ *
+ * Decrement the refcount, and if 0, call config_item_cleanup().
+ */
+void config_item_put(struct config_item * item)
+{
+ if (item)
+ kref_put(&item->ci_kref, config_item_release);
+}
+
+
+/**
+ * config_group_init - initialize a group for use
+ * @k: group
+ */
+
+void config_group_init(struct config_group *group)
+{
+ config_item_init(&group->cg_item);
+ INIT_LIST_HEAD(&group->cg_children);
+}
+
+
+/**
+ * config_group_find_obj - search for item in group.
+ * @group: group we're looking in.
+ * @name: item's name.
+ *
+ * Lock group via @group->cg_subsys, and iterate over @group->cg_list,
+ * looking for a matching config_item. If matching item is found
+ * take a reference and return the item.
+ */
+
+struct config_item * config_group_find_obj(struct config_group * group, const char * name)
+{
+ struct list_head * entry;
+ struct config_item * ret = NULL;
+
+ /* XXX LOCKING! */
+ list_for_each(entry,&group->cg_children) {
+ struct config_item * item = to_item(entry);
+ if (config_item_name(item) &&
+ !strcmp(config_item_name(item), name)) {
+ ret = config_item_get(item);
+ break;
+ }
+ }
+ return ret;
+}
+
+
+EXPORT_SYMBOL(config_item_init);
+EXPORT_SYMBOL(config_group_init);
+EXPORT_SYMBOL(config_item_get);
+EXPORT_SYMBOL(config_item_put);
+