[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/dir.c b/fs/configfs/dir.c
new file mode 100644
index 0000000..e48b539
--- /dev/null
+++ b/fs/configfs/dir.c
@@ -0,0 +1,1102 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * dir.c - Operations for configfs directories.
+ *
+ * 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 sysfs:
+ * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
+ *
+ * configfs Copyright (C) 2005 Oracle. All rights reserved.
+ */
+
+#undef DEBUG
+
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+#include <linux/configfs.h>
+#include "configfs_internal.h"
+
+DECLARE_RWSEM(configfs_rename_sem);
+
+static void configfs_d_iput(struct dentry * dentry,
+ struct inode * inode)
+{
+ struct configfs_dirent * sd = dentry->d_fsdata;
+
+ if (sd) {
+ BUG_ON(sd->s_dentry != dentry);
+ sd->s_dentry = NULL;
+ configfs_put(sd);
+ }
+ iput(inode);
+}
+
+/*
+ * We _must_ delete our dentries on last dput, as the chain-to-parent
+ * behavior is required to clear the parents of default_groups.
+ */
+static int configfs_d_delete(struct dentry *dentry)
+{
+ return 1;
+}
+
+static struct dentry_operations configfs_dentry_ops = {
+ .d_iput = configfs_d_iput,
+ /* simple_delete_dentry() isn't exported */
+ .d_delete = configfs_d_delete,
+};
+
+/*
+ * Allocates a new configfs_dirent and links it to the parent configfs_dirent
+ */
+static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent * parent_sd,
+ void * element)
+{
+ struct configfs_dirent * sd;
+
+ sd = kmalloc(sizeof(*sd), GFP_KERNEL);
+ if (!sd)
+ return NULL;
+
+ memset(sd, 0, sizeof(*sd));
+ atomic_set(&sd->s_count, 1);
+ INIT_LIST_HEAD(&sd->s_links);
+ INIT_LIST_HEAD(&sd->s_children);
+ list_add(&sd->s_sibling, &parent_sd->s_children);
+ sd->s_element = element;
+
+ return sd;
+}
+
+int configfs_make_dirent(struct configfs_dirent * parent_sd,
+ struct dentry * dentry, void * element,
+ umode_t mode, int type)
+{
+ struct configfs_dirent * sd;
+
+ sd = configfs_new_dirent(parent_sd, element);
+ if (!sd)
+ return -ENOMEM;
+
+ sd->s_mode = mode;
+ sd->s_type = type;
+ sd->s_dentry = dentry;
+ if (dentry) {
+ dentry->d_fsdata = configfs_get(sd);
+ dentry->d_op = &configfs_dentry_ops;
+ }
+
+ return 0;
+}
+
+static int init_dir(struct inode * inode)
+{
+ inode->i_op = &configfs_dir_inode_operations;
+ inode->i_fop = &configfs_dir_operations;
+
+ /* directory inodes start off with i_nlink == 2 (for "." entry) */
+ inode->i_nlink++;
+ return 0;
+}
+
+static int init_file(struct inode * inode)
+{
+ inode->i_size = PAGE_SIZE;
+ inode->i_fop = &configfs_file_operations;
+ return 0;
+}
+
+static int init_symlink(struct inode * inode)
+{
+ inode->i_op = &configfs_symlink_inode_operations;
+ return 0;
+}
+
+static int create_dir(struct config_item * k, struct dentry * p,
+ struct dentry * d)
+{
+ int error;
+ umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
+
+ error = configfs_create(d, mode, init_dir);
+ if (!error) {
+ error = configfs_make_dirent(p->d_fsdata, d, k, mode,
+ CONFIGFS_DIR);
+ if (!error) {
+ p->d_inode->i_nlink++;
+ (d)->d_op = &configfs_dentry_ops;
+ }
+ }
+ return error;
+}
+
+
+/**
+ * configfs_create_dir - create a directory for an config_item.
+ * @item: config_itemwe're creating directory for.
+ * @dentry: config_item's dentry.
+ */
+
+static int configfs_create_dir(struct config_item * item, struct dentry *dentry)
+{
+ struct dentry * parent;
+ int error = 0;
+
+ BUG_ON(!item);
+
+ if (item->ci_parent)
+ parent = item->ci_parent->ci_dentry;
+ else if (configfs_mount && configfs_mount->mnt_sb)
+ parent = configfs_mount->mnt_sb->s_root;
+ else
+ return -EFAULT;
+
+ error = create_dir(item,parent,dentry);
+ if (!error)
+ item->ci_dentry = dentry;
+ return error;
+}
+
+int configfs_create_link(struct configfs_symlink *sl,
+ struct dentry *parent,
+ struct dentry *dentry)
+{
+ int err = 0;
+ umode_t mode = S_IFLNK | S_IRWXUGO;
+
+ err = configfs_create(dentry, mode, init_symlink);
+ if (!err) {
+ err = configfs_make_dirent(parent->d_fsdata, dentry, sl,
+ mode, CONFIGFS_ITEM_LINK);
+ if (!err)
+ dentry->d_op = &configfs_dentry_ops;
+ }
+ return err;
+}
+
+static void remove_dir(struct dentry * d)
+{
+ struct dentry * parent = dget(d->d_parent);
+ struct configfs_dirent * sd;
+
+ sd = d->d_fsdata;
+ list_del_init(&sd->s_sibling);
+ configfs_put(sd);
+ if (d->d_inode)
+ simple_rmdir(parent->d_inode,d);
+
+ pr_debug(" o %s removing done (%d)\n",d->d_name.name,
+ atomic_read(&d->d_count));
+
+ dput(parent);
+}
+
+/**
+ * configfs_remove_dir - remove an config_item's directory.
+ * @item: config_item we're removing.
+ *
+ * The only thing special about this is that we remove any files in
+ * the directory before we remove the directory, and we've inlined
+ * what used to be configfs_rmdir() below, instead of calling separately.
+ */
+
+static void configfs_remove_dir(struct config_item * item)
+{
+ struct dentry * dentry = dget(item->ci_dentry);
+
+ if (!dentry)
+ return;
+
+ remove_dir(dentry);
+ /**
+ * Drop reference from dget() on entrance.
+ */
+ dput(dentry);
+}
+
+
+/* attaches attribute's configfs_dirent to the dentry corresponding to the
+ * attribute file
+ */
+static int configfs_attach_attr(struct configfs_dirent * sd, struct dentry * dentry)
+{
+ struct configfs_attribute * attr = sd->s_element;
+ int error;
+
+ error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG, init_file);
+ if (error)
+ return error;
+
+ dentry->d_op = &configfs_dentry_ops;
+ dentry->d_fsdata = configfs_get(sd);
+ sd->s_dentry = dentry;
+ d_rehash(dentry);
+
+ return 0;
+}
+
+static struct dentry * configfs_lookup(struct inode *dir,
+ struct dentry *dentry,
+ struct nameidata *nd)
+{
+ struct configfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
+ struct configfs_dirent * sd;
+ int found = 0;
+ int err = 0;
+
+ list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
+ if (sd->s_type & CONFIGFS_NOT_PINNED) {
+ const unsigned char * name = configfs_get_name(sd);
+
+ if (strcmp(name, dentry->d_name.name))
+ continue;
+
+ found = 1;
+ err = configfs_attach_attr(sd, dentry);
+ break;
+ }
+ }
+
+ if (!found) {
+ /*
+ * If it doesn't exist and it isn't a NOT_PINNED item,
+ * it must be negative.
+ */
+ return simple_lookup(dir, dentry, nd);
+ }
+
+ return ERR_PTR(err);
+}
+
+/*
+ * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
+ * attributes and are removed by rmdir(). We recurse, taking i_sem
+ * on all children that are candidates for default detach. If the
+ * result is clean, then configfs_detach_group() will handle dropping
+ * i_sem. If there is an error, the caller will clean up the i_sem
+ * holders via configfs_detach_rollback().
+ */
+static int configfs_detach_prep(struct dentry *dentry)
+{
+ struct configfs_dirent *parent_sd = dentry->d_fsdata;
+ struct configfs_dirent *sd;
+ int ret;
+
+ ret = -EBUSY;
+ if (!list_empty(&parent_sd->s_links))
+ goto out;
+
+ ret = 0;
+ list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
+ if (sd->s_type & CONFIGFS_NOT_PINNED)
+ continue;
+ if (sd->s_type & CONFIGFS_USET_DEFAULT) {
+ down(&sd->s_dentry->d_inode->i_sem);
+ /* Mark that we've taken i_sem */
+ sd->s_type |= CONFIGFS_USET_DROPPING;
+
+ ret = configfs_detach_prep(sd->s_dentry);
+ if (!ret)
+ continue;
+ } else
+ ret = -ENOTEMPTY;
+
+ break;
+ }
+
+out:
+ return ret;
+}
+
+/*
+ * Walk the tree, dropping i_sem wherever CONFIGFS_USET_DROPPING is
+ * set.
+ */
+static void configfs_detach_rollback(struct dentry *dentry)
+{
+ struct configfs_dirent *parent_sd = dentry->d_fsdata;
+ struct configfs_dirent *sd;
+
+ list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
+ if (sd->s_type & CONFIGFS_USET_DEFAULT) {
+ configfs_detach_rollback(sd->s_dentry);
+
+ if (sd->s_type & CONFIGFS_USET_DROPPING) {
+ sd->s_type &= ~CONFIGFS_USET_DROPPING;
+ up(&sd->s_dentry->d_inode->i_sem);
+ }
+ }
+ }
+}
+
+static void detach_attrs(struct config_item * item)
+{
+ struct dentry * dentry = dget(item->ci_dentry);
+ struct configfs_dirent * parent_sd;
+ struct configfs_dirent * sd, * tmp;
+
+ if (!dentry)
+ return;
+
+ pr_debug("configfs %s: dropping attrs for dir\n",
+ dentry->d_name.name);
+
+ parent_sd = dentry->d_fsdata;
+ list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
+ if (!sd->s_element || !(sd->s_type & CONFIGFS_NOT_PINNED))
+ continue;
+ list_del_init(&sd->s_sibling);
+ configfs_drop_dentry(sd, dentry);
+ configfs_put(sd);
+ }
+
+ /**
+ * Drop reference from dget() on entrance.
+ */
+ dput(dentry);
+}
+
+static int populate_attrs(struct config_item *item)
+{
+ struct config_item_type *t = item->ci_type;
+ struct configfs_attribute *attr;
+ int error = 0;
+ int i;
+
+ if (!t)
+ return -EINVAL;
+ if (t->ct_attrs) {
+ for (i = 0; (attr = t->ct_attrs[i]) != NULL; i++) {
+ if ((error = configfs_create_file(item, attr)))
+ break;
+ }
+ }
+
+ if (error)
+ detach_attrs(item);
+
+ return error;
+}
+
+static int configfs_attach_group(struct config_item *parent_item,
+ struct config_item *item,
+ struct dentry *dentry);
+static void configfs_detach_group(struct config_item *item);
+
+static void detach_groups(struct config_group *group)
+{
+ struct dentry * dentry = dget(group->cg_item.ci_dentry);
+ struct dentry *child;
+ struct configfs_dirent *parent_sd;
+ struct configfs_dirent *sd, *tmp;
+
+ if (!dentry)
+ return;
+
+ parent_sd = dentry->d_fsdata;
+ list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
+ if (!sd->s_element ||
+ !(sd->s_type & CONFIGFS_USET_DEFAULT))
+ continue;
+
+ child = sd->s_dentry;
+
+ configfs_detach_group(sd->s_element);
+ child->d_inode->i_flags |= S_DEAD;
+
+ /*
+ * From rmdir/unregister, a configfs_detach_prep() pass
+ * has taken our i_sem for us. Drop it.
+ * From mkdir/register cleanup, there is no sem held.
+ */
+ if (sd->s_type & CONFIGFS_USET_DROPPING)
+ up(&child->d_inode->i_sem);
+
+ d_delete(child);
+ dput(child);
+ }
+
+ /**
+ * Drop reference from dget() on entrance.
+ */
+ dput(dentry);
+}
+
+/*
+ * This fakes mkdir(2) on a default_groups[] entry. It
+ * creates a dentry, attachs it, and then does fixup
+ * on the sd->s_type.
+ *
+ * We could, perhaps, tweak our parent's ->mkdir for a minute and
+ * try using vfs_mkdir. Just a thought.
+ */
+static int create_default_group(struct config_group *parent_group,
+ struct config_group *group)
+{
+ int ret;
+ struct qstr name;
+ struct configfs_dirent *sd;
+ /* We trust the caller holds a reference to parent */
+ struct dentry *child, *parent = parent_group->cg_item.ci_dentry;
+
+ if (!group->cg_item.ci_name)
+ group->cg_item.ci_name = group->cg_item.ci_namebuf;
+ name.name = group->cg_item.ci_name;
+ name.len = strlen(name.name);
+ name.hash = full_name_hash(name.name, name.len);
+
+ ret = -ENOMEM;
+ child = d_alloc(parent, &name);
+ if (child) {
+ d_add(child, NULL);
+
+ ret = configfs_attach_group(&parent_group->cg_item,
+ &group->cg_item, child);
+ if (!ret) {
+ sd = child->d_fsdata;
+ sd->s_type |= CONFIGFS_USET_DEFAULT;
+ } else {
+ d_delete(child);
+ dput(child);
+ }
+ }
+
+ return ret;
+}
+
+static int populate_groups(struct config_group *group)
+{
+ struct config_group *new_group;
+ struct dentry *dentry = group->cg_item.ci_dentry;
+ int ret = 0;
+ int i;
+
+ if (group && group->default_groups) {
+ /* FYI, we're faking mkdir here
+ * I'm not sure we need this semaphore, as we're called
+ * from our parent's mkdir. That holds our parent's
+ * i_sem, so afaik lookup cannot continue through our
+ * parent to find us, let alone mess with our tree.
+ * That said, taking our i_sem is closer to mkdir
+ * emulation, and shouldn't hurt. */
+ down(&dentry->d_inode->i_sem);
+
+ for (i = 0; group->default_groups[i]; i++) {
+ new_group = group->default_groups[i];
+
+ ret = create_default_group(group, new_group);
+ if (ret)
+ break;
+ }
+
+ up(&dentry->d_inode->i_sem);
+ }
+
+ if (ret)
+ detach_groups(group);
+
+ return ret;
+}
+
+/*
+ * All of link_obj/unlink_obj/link_group/unlink_group require that
+ * subsys->su_sem is held.
+ */
+
+static void unlink_obj(struct config_item *item)
+{
+ struct config_group *group;
+
+ group = item->ci_group;
+ if (group) {
+ list_del_init(&item->ci_entry);
+
+ item->ci_group = NULL;
+ item->ci_parent = NULL;
+ config_item_put(item);
+
+ config_group_put(group);
+ }
+}
+
+static void link_obj(struct config_item *parent_item, struct config_item *item)
+{
+ /* Parent seems redundant with group, but it makes certain
+ * traversals much nicer. */
+ item->ci_parent = parent_item;
+ item->ci_group = config_group_get(to_config_group(parent_item));
+ list_add_tail(&item->ci_entry, &item->ci_group->cg_children);
+
+ config_item_get(item);
+}
+
+static void unlink_group(struct config_group *group)
+{
+ int i;
+ struct config_group *new_group;
+
+ if (group->default_groups) {
+ for (i = 0; group->default_groups[i]; i++) {
+ new_group = group->default_groups[i];
+ unlink_group(new_group);
+ }
+ }
+
+ group->cg_subsys = NULL;
+ unlink_obj(&group->cg_item);
+}
+
+static void link_group(struct config_group *parent_group, struct config_group *group)
+{
+ int i;
+ struct config_group *new_group;
+ struct configfs_subsystem *subsys = NULL; /* gcc is a turd */
+
+ link_obj(&parent_group->cg_item, &group->cg_item);
+
+ if (parent_group->cg_subsys)
+ subsys = parent_group->cg_subsys;
+ else if (configfs_is_root(&parent_group->cg_item))
+ subsys = to_configfs_subsystem(group);
+ else
+ BUG();
+ group->cg_subsys = subsys;
+
+ if (group->default_groups) {
+ for (i = 0; group->default_groups[i]; i++) {
+ new_group = group->default_groups[i];
+ link_group(group, new_group);
+ }
+ }
+}
+
+/*
+ * The goal is that configfs_attach_item() (and
+ * configfs_attach_group()) can be called from either the VFS or this
+ * module. That is, they assume that the items have been created,
+ * the dentry allocated, and the dcache is all ready to go.
+ *
+ * If they fail, they must clean up after themselves as if they
+ * had never been called. The caller (VFS or local function) will
+ * handle cleaning up the dcache bits.
+ *
+ * configfs_detach_group() and configfs_detach_item() behave similarly on
+ * the way out. They assume that the proper semaphores are held, they
+ * clean up the configfs items, and they expect their callers will
+ * handle the dcache bits.
+ */
+static int configfs_attach_item(struct config_item *parent_item,
+ struct config_item *item,
+ struct dentry *dentry)
+{
+ int ret;
+
+ ret = configfs_create_dir(item, dentry);
+ if (!ret) {
+ ret = populate_attrs(item);
+ if (ret) {
+ configfs_remove_dir(item);
+ d_delete(dentry);
+ }
+ }
+
+ return ret;
+}
+
+static void configfs_detach_item(struct config_item *item)
+{
+ detach_attrs(item);
+ configfs_remove_dir(item);
+}
+
+static int configfs_attach_group(struct config_item *parent_item,
+ struct config_item *item,
+ struct dentry *dentry)
+{
+ int ret;
+ struct configfs_dirent *sd;
+
+ ret = configfs_attach_item(parent_item, item, dentry);
+ if (!ret) {
+ sd = dentry->d_fsdata;
+ sd->s_type |= CONFIGFS_USET_DIR;
+
+ ret = populate_groups(to_config_group(item));
+ if (ret) {
+ configfs_detach_item(item);
+ d_delete(dentry);
+ }
+ }
+
+ return ret;
+}
+
+static void configfs_detach_group(struct config_item *item)
+{
+ detach_groups(to_config_group(item));
+ configfs_detach_item(item);
+}
+
+/*
+ * Drop the initial reference from make_item()/make_group()
+ * This function assumes that reference is held on item
+ * and that item holds a valid reference to the parent. Also, it
+ * assumes the caller has validated ci_type.
+ */
+static void client_drop_item(struct config_item *parent_item,
+ struct config_item *item)
+{
+ struct config_item_type *type;
+
+ type = parent_item->ci_type;
+ BUG_ON(!type);
+
+ if (type->ct_group_ops && type->ct_group_ops->drop_item)
+ type->ct_group_ops->drop_item(to_config_group(parent_item),
+ item);
+ else
+ config_item_put(item);
+}
+
+
+static int configfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
+{
+ int ret;
+ struct config_group *group;
+ struct config_item *item;
+ struct config_item *parent_item;
+ struct configfs_subsystem *subsys;
+ struct configfs_dirent *sd;
+ struct config_item_type *type;
+ struct module *owner;
+ char *name;
+
+ if (dentry->d_parent == configfs_sb->s_root)
+ return -EPERM;
+
+ sd = dentry->d_parent->d_fsdata;
+ if (!(sd->s_type & CONFIGFS_USET_DIR))
+ return -EPERM;
+
+ parent_item = configfs_get_config_item(dentry->d_parent);
+ type = parent_item->ci_type;
+ subsys = to_config_group(parent_item)->cg_subsys;
+ BUG_ON(!subsys);
+
+ if (!type || !type->ct_group_ops ||
+ (!type->ct_group_ops->make_group &&
+ !type->ct_group_ops->make_item)) {
+ config_item_put(parent_item);
+ return -EPERM; /* What lack-of-mkdir returns */
+ }
+
+ name = kmalloc(dentry->d_name.len + 1, GFP_KERNEL);
+ if (!name) {
+ config_item_put(parent_item);
+ return -ENOMEM;
+ }
+ snprintf(name, dentry->d_name.len + 1, "%s", dentry->d_name.name);
+
+ down(&subsys->su_sem);
+ group = NULL;
+ item = NULL;
+ if (type->ct_group_ops->make_group) {
+ group = type->ct_group_ops->make_group(to_config_group(parent_item), name);
+ if (group) {
+ link_group(to_config_group(parent_item), group);
+ item = &group->cg_item;
+ }
+ } else {
+ item = type->ct_group_ops->make_item(to_config_group(parent_item), name);
+ if (item)
+ link_obj(parent_item, item);
+ }
+ up(&subsys->su_sem);
+
+ kfree(name);
+ if (!item) {
+ config_item_put(parent_item);
+ return -ENOMEM;
+ }
+
+ ret = -EINVAL;
+ type = item->ci_type;
+ if (type) {
+ owner = type->ct_owner;
+ if (try_module_get(owner)) {
+ if (group) {
+ ret = configfs_attach_group(parent_item,
+ item,
+ dentry);
+ } else {
+ ret = configfs_attach_item(parent_item,
+ item,
+ dentry);
+ }
+
+ if (ret) {
+ down(&subsys->su_sem);
+ if (group)
+ unlink_group(group);
+ else
+ unlink_obj(item);
+ client_drop_item(parent_item, item);
+ up(&subsys->su_sem);
+
+ config_item_put(parent_item);
+ module_put(owner);
+ }
+ }
+ }
+
+ return ret;
+}
+
+static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
+{
+ struct config_item *parent_item;
+ struct config_item *item;
+ struct configfs_subsystem *subsys;
+ struct configfs_dirent *sd;
+ struct module *owner = NULL;
+ int ret;
+
+ if (dentry->d_parent == configfs_sb->s_root)
+ return -EPERM;
+
+ sd = dentry->d_fsdata;
+ if (sd->s_type & CONFIGFS_USET_DEFAULT)
+ return -EPERM;
+
+ parent_item = configfs_get_config_item(dentry->d_parent);
+ subsys = to_config_group(parent_item)->cg_subsys;
+ BUG_ON(!subsys);
+
+ if (!parent_item->ci_type) {
+ config_item_put(parent_item);
+ return -EINVAL;
+ }
+
+ ret = configfs_detach_prep(dentry);
+ if (ret) {
+ configfs_detach_rollback(dentry);
+ config_item_put(parent_item);
+ return ret;
+ }
+
+ item = configfs_get_config_item(dentry);
+
+ /* Drop reference from above, item already holds one. */
+ config_item_put(parent_item);
+
+ if (item->ci_type)
+ owner = item->ci_type->ct_owner;
+
+ if (sd->s_type & CONFIGFS_USET_DIR) {
+ configfs_detach_group(item);
+
+ down(&subsys->su_sem);
+ unlink_group(to_config_group(item));
+ } else {
+ configfs_detach_item(item);
+
+ down(&subsys->su_sem);
+ unlink_obj(item);
+ }
+
+ client_drop_item(parent_item, item);
+ up(&subsys->su_sem);
+
+ /* Drop our reference from above */
+ config_item_put(item);
+
+ module_put(owner);
+
+ return 0;
+}
+
+struct inode_operations configfs_dir_inode_operations = {
+ .mkdir = configfs_mkdir,
+ .rmdir = configfs_rmdir,
+ .symlink = configfs_symlink,
+ .unlink = configfs_unlink,
+ .lookup = configfs_lookup,
+};
+
+#if 0
+int configfs_rename_dir(struct config_item * item, const char *new_name)
+{
+ int error = 0;
+ struct dentry * new_dentry, * parent;
+
+ if (!strcmp(config_item_name(item), new_name))
+ return -EINVAL;
+
+ if (!item->parent)
+ return -EINVAL;
+
+ down_write(&configfs_rename_sem);
+ parent = item->parent->dentry;
+
+ down(&parent->d_inode->i_sem);
+
+ new_dentry = lookup_one_len(new_name, parent, strlen(new_name));
+ if (!IS_ERR(new_dentry)) {
+ if (!new_dentry->d_inode) {
+ error = config_item_set_name(item, "%s", new_name);
+ if (!error) {
+ d_add(new_dentry, NULL);
+ d_move(item->dentry, new_dentry);
+ }
+ else
+ d_delete(new_dentry);
+ } else
+ error = -EEXIST;
+ dput(new_dentry);
+ }
+ up(&parent->d_inode->i_sem);
+ up_write(&configfs_rename_sem);
+
+ return error;
+}
+#endif
+
+static int configfs_dir_open(struct inode *inode, struct file *file)
+{
+ struct dentry * dentry = file->f_dentry;
+ struct configfs_dirent * parent_sd = dentry->d_fsdata;
+
+ down(&dentry->d_inode->i_sem);
+ file->private_data = configfs_new_dirent(parent_sd, NULL);
+ up(&dentry->d_inode->i_sem);
+
+ return file->private_data ? 0 : -ENOMEM;
+
+}
+
+static int configfs_dir_close(struct inode *inode, struct file *file)
+{
+ struct dentry * dentry = file->f_dentry;
+ struct configfs_dirent * cursor = file->private_data;
+
+ down(&dentry->d_inode->i_sem);
+ list_del_init(&cursor->s_sibling);
+ up(&dentry->d_inode->i_sem);
+
+ release_configfs_dirent(cursor);
+
+ return 0;
+}
+
+/* Relationship between s_mode and the DT_xxx types */
+static inline unsigned char dt_type(struct configfs_dirent *sd)
+{
+ return (sd->s_mode >> 12) & 15;
+}
+
+static int configfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
+{
+ struct dentry *dentry = filp->f_dentry;
+ struct configfs_dirent * parent_sd = dentry->d_fsdata;
+ struct configfs_dirent *cursor = filp->private_data;
+ struct list_head *p, *q = &cursor->s_sibling;
+ ino_t ino;
+ int i = filp->f_pos;
+
+ switch (i) {
+ case 0:
+ ino = dentry->d_inode->i_ino;
+ if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
+ break;
+ filp->f_pos++;
+ i++;
+ /* fallthrough */
+ case 1:
+ ino = parent_ino(dentry);
+ if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
+ break;
+ filp->f_pos++;
+ i++;
+ /* fallthrough */
+ default:
+ if (filp->f_pos == 2) {
+ list_del(q);
+ list_add(q, &parent_sd->s_children);
+ }
+ for (p=q->next; p!= &parent_sd->s_children; p=p->next) {
+ struct configfs_dirent *next;
+ const char * name;
+ int len;
+
+ next = list_entry(p, struct configfs_dirent,
+ s_sibling);
+ if (!next->s_element)
+ continue;
+
+ name = configfs_get_name(next);
+ len = strlen(name);
+ if (next->s_dentry)
+ ino = next->s_dentry->d_inode->i_ino;
+ else
+ ino = iunique(configfs_sb, 2);
+
+ if (filldir(dirent, name, len, filp->f_pos, ino,
+ dt_type(next)) < 0)
+ return 0;
+
+ list_del(q);
+ list_add(q, p);
+ p = q;
+ filp->f_pos++;
+ }
+ }
+ return 0;
+}
+
+static loff_t configfs_dir_lseek(struct file * file, loff_t offset, int origin)
+{
+ struct dentry * dentry = file->f_dentry;
+
+ down(&dentry->d_inode->i_sem);
+ switch (origin) {
+ case 1:
+ offset += file->f_pos;
+ case 0:
+ if (offset >= 0)
+ break;
+ default:
+ up(&file->f_dentry->d_inode->i_sem);
+ return -EINVAL;
+ }
+ if (offset != file->f_pos) {
+ file->f_pos = offset;
+ if (file->f_pos >= 2) {
+ struct configfs_dirent *sd = dentry->d_fsdata;
+ struct configfs_dirent *cursor = file->private_data;
+ struct list_head *p;
+ loff_t n = file->f_pos - 2;
+
+ list_del(&cursor->s_sibling);
+ p = sd->s_children.next;
+ while (n && p != &sd->s_children) {
+ struct configfs_dirent *next;
+ next = list_entry(p, struct configfs_dirent,
+ s_sibling);
+ if (next->s_element)
+ n--;
+ p = p->next;
+ }
+ list_add_tail(&cursor->s_sibling, p);
+ }
+ }
+ up(&dentry->d_inode->i_sem);
+ return offset;
+}
+
+struct file_operations configfs_dir_operations = {
+ .open = configfs_dir_open,
+ .release = configfs_dir_close,
+ .llseek = configfs_dir_lseek,
+ .read = generic_read_dir,
+ .readdir = configfs_readdir,
+};
+
+int configfs_register_subsystem(struct configfs_subsystem *subsys)
+{
+ int err;
+ struct config_group *group = &subsys->su_group;
+ struct qstr name;
+ struct dentry *dentry;
+ struct configfs_dirent *sd;
+
+ err = configfs_pin_fs();
+ if (err)
+ return err;
+
+ if (!group->cg_item.ci_name)
+ group->cg_item.ci_name = group->cg_item.ci_namebuf;
+
+ sd = configfs_sb->s_root->d_fsdata;
+ link_group(to_config_group(sd->s_element), group);
+
+ down(&configfs_sb->s_root->d_inode->i_sem);
+
+ name.name = group->cg_item.ci_name;
+ name.len = strlen(name.name);
+ name.hash = full_name_hash(name.name, name.len);
+
+ err = -ENOMEM;
+ dentry = d_alloc(configfs_sb->s_root, &name);
+ if (!dentry)
+ goto out_release;
+
+ d_add(dentry, NULL);
+
+ err = configfs_attach_group(sd->s_element, &group->cg_item,
+ dentry);
+ if (!err)
+ dentry = NULL;
+ else
+ d_delete(dentry);
+
+ up(&configfs_sb->s_root->d_inode->i_sem);
+
+ if (dentry) {
+ dput(dentry);
+out_release:
+ unlink_group(group);
+ configfs_release_fs();
+ }
+
+ return err;
+}
+
+void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
+{
+ struct config_group *group = &subsys->su_group;
+ struct dentry *dentry = group->cg_item.ci_dentry;
+
+ if (dentry->d_parent != configfs_sb->s_root) {
+ printk(KERN_ERR "configfs: Tried to unregister non-subsystem!\n");
+ return;
+ }
+
+ down(&configfs_sb->s_root->d_inode->i_sem);
+ down(&dentry->d_inode->i_sem);
+ if (configfs_detach_prep(dentry)) {
+ printk(KERN_ERR "configfs: Tried to unregister non-empty subsystem!\n");
+ }
+ configfs_detach_group(&group->cg_item);
+ dentry->d_inode->i_flags |= S_DEAD;
+ up(&dentry->d_inode->i_sem);
+
+ d_delete(dentry);
+
+ up(&configfs_sb->s_root->d_inode->i_sem);
+
+ dput(dentry);
+
+ unlink_group(group);
+ configfs_release_fs();
+}
+
+EXPORT_SYMBOL(configfs_register_subsystem);
+EXPORT_SYMBOL(configfs_unregister_subsystem);