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Diffstat (limited to 'fs/configfs/dir.c')
| -rw-r--r-- | fs/configfs/dir.c | 1724 |
1 files changed, 1724 insertions, 0 deletions
diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c new file mode 100644 index 000000000..c81ce7f20 --- /dev/null +++ b/fs/configfs/dir.c @@ -0,0 +1,1724 @@ +/* -*- 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/err.h> + +#include <linux/configfs.h> +#include "configfs_internal.h" + +DECLARE_RWSEM(configfs_rename_sem); +/* + * Protects mutations of configfs_dirent linkage together with proper i_mutex + * Also protects mutations of symlinks linkage to target configfs_dirent + * Mutators of configfs_dirent linkage must *both* have the proper inode locked + * and configfs_dirent_lock locked, in that order. + * This allows one to safely traverse configfs_dirent trees and symlinks without + * having to lock inodes. + * + * Protects setting of CONFIGFS_USET_DROPPING: checking the flag + * unlocked is not reliable unless in detach_groups() called from + * rmdir()/unregister() and from configfs_attach_group() + */ +DEFINE_SPINLOCK(configfs_dirent_lock); + +static void configfs_d_iput(struct dentry * dentry, + struct inode * inode) +{ + struct configfs_dirent *sd = dentry->d_fsdata; + + if (sd) { + /* Coordinate with configfs_readdir */ + spin_lock(&configfs_dirent_lock); + /* Coordinate with configfs_attach_attr where will increase + * sd->s_count and update sd->s_dentry to new allocated one. + * Only set sd->dentry to null when this dentry is the only + * sd owner. + * If not do so, configfs_d_iput may run just after + * configfs_attach_attr and set sd->s_dentry to null + * even it's still in use. + */ + if (atomic_read(&sd->s_count) <= 2) + sd->s_dentry = NULL; + + spin_unlock(&configfs_dirent_lock); + configfs_put(sd); + } + iput(inode); +} + +const struct dentry_operations configfs_dentry_ops = { + .d_iput = configfs_d_iput, + .d_delete = always_delete_dentry, +}; + +#ifdef CONFIG_LOCKDEP + +/* + * Helpers to make lockdep happy with our recursive locking of default groups' + * inodes (see configfs_attach_group() and configfs_detach_group()). + * We put default groups i_mutexes in separate classes according to their depth + * from the youngest non-default group ancestor. + * + * For a non-default group A having default groups A/B, A/C, and A/C/D, default + * groups A/B and A/C will have their inode's mutex in class + * default_group_class[0], and default group A/C/D will be in + * default_group_class[1]. + * + * The lock classes are declared and assigned in inode.c, according to the + * s_depth value. + * The s_depth value is initialized to -1, adjusted to >= 0 when attaching + * default groups, and reset to -1 when all default groups are attached. During + * attachment, if configfs_create() sees s_depth > 0, the lock class of the new + * inode's mutex is set to default_group_class[s_depth - 1]. + */ + +static void configfs_init_dirent_depth(struct configfs_dirent *sd) +{ + sd->s_depth = -1; +} + +static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd, + struct configfs_dirent *sd) +{ + int parent_depth = parent_sd->s_depth; + + if (parent_depth >= 0) + sd->s_depth = parent_depth + 1; +} + +static void +configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd) +{ + /* + * item's i_mutex class is already setup, so s_depth is now only + * used to set new sub-directories s_depth, which is always done + * with item's i_mutex locked. + */ + /* + * sd->s_depth == -1 iff we are a non default group. + * else (we are a default group) sd->s_depth > 0 (see + * create_dir()). + */ + if (sd->s_depth == -1) + /* + * We are a non default group and we are going to create + * default groups. + */ + sd->s_depth = 0; +} + +static void +configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd) +{ + /* We will not create default groups anymore. */ + sd->s_depth = -1; +} + +#else /* CONFIG_LOCKDEP */ + +static void configfs_init_dirent_depth(struct configfs_dirent *sd) +{ +} + +static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd, + struct configfs_dirent *sd) +{ +} + +static void +configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd) +{ +} + +static void +configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd) +{ +} + +#endif /* CONFIG_LOCKDEP */ + +/* + * 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, int type) +{ + struct configfs_dirent * sd; + + sd = kmem_cache_zalloc(configfs_dir_cachep, GFP_KERNEL); + if (!sd) + return ERR_PTR(-ENOMEM); + + atomic_set(&sd->s_count, 1); + INIT_LIST_HEAD(&sd->s_links); + INIT_LIST_HEAD(&sd->s_children); + sd->s_element = element; + sd->s_type = type; + configfs_init_dirent_depth(sd); + spin_lock(&configfs_dirent_lock); + if (parent_sd->s_type & CONFIGFS_USET_DROPPING) { + spin_unlock(&configfs_dirent_lock); + kmem_cache_free(configfs_dir_cachep, sd); + return ERR_PTR(-ENOENT); + } + list_add(&sd->s_sibling, &parent_sd->s_children); + spin_unlock(&configfs_dirent_lock); + + return sd; +} + +/* + * + * Return -EEXIST if there is already a configfs element with the same + * name for the same parent. + * + * called with parent inode's i_mutex held + */ +static int configfs_dirent_exists(struct configfs_dirent *parent_sd, + const unsigned char *new) +{ + struct configfs_dirent * sd; + + list_for_each_entry(sd, &parent_sd->s_children, s_sibling) { + if (sd->s_element) { + const unsigned char *existing = configfs_get_name(sd); + if (strcmp(existing, new)) + continue; + else + return -EEXIST; + } + } + + return 0; +} + + +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, type); + if (IS_ERR(sd)) + return PTR_ERR(sd); + + sd->s_mode = mode; + sd->s_dentry = dentry; + if (dentry) + dentry->d_fsdata = configfs_get(sd); + + return 0; +} + +static void 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) */ + inc_nlink(inode); +} + +static void configfs_init_file(struct inode * inode) +{ + inode->i_size = PAGE_SIZE; + inode->i_fop = &configfs_file_operations; +} + +static void init_symlink(struct inode * inode) +{ + inode->i_op = &configfs_symlink_inode_operations; +} + +/** + * configfs_create_dir - create a directory for an config_item. + * @item: config_itemwe're creating directory for. + * @dentry: config_item's dentry. + * + * Note: user-created entries won't be allowed under this new directory + * until it is validated by configfs_dir_set_ready() + */ + +static int configfs_create_dir(struct config_item *item, struct dentry *dentry) +{ + int error; + umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO; + struct dentry *p = dentry->d_parent; + + BUG_ON(!item); + + error = configfs_dirent_exists(p->d_fsdata, dentry->d_name.name); + if (unlikely(error)) + return error; + + error = configfs_make_dirent(p->d_fsdata, dentry, item, mode, + CONFIGFS_DIR | CONFIGFS_USET_CREATING); + if (unlikely(error)) + return error; + + configfs_set_dir_dirent_depth(p->d_fsdata, dentry->d_fsdata); + error = configfs_create(dentry, mode, init_dir); + if (!error) { + inc_nlink(d_inode(p)); + item->ci_dentry = dentry; + } else { + struct configfs_dirent *sd = dentry->d_fsdata; + if (sd) { + spin_lock(&configfs_dirent_lock); + list_del_init(&sd->s_sibling); + spin_unlock(&configfs_dirent_lock); + configfs_put(sd); + } + } + return error; +} + +/* + * Allow userspace to create new entries under a new directory created with + * configfs_create_dir(), and under all of its chidlren directories recursively. + * @sd configfs_dirent of the new directory to validate + * + * Caller must hold configfs_dirent_lock. + */ +static void configfs_dir_set_ready(struct configfs_dirent *sd) +{ + struct configfs_dirent *child_sd; + + sd->s_type &= ~CONFIGFS_USET_CREATING; + list_for_each_entry(child_sd, &sd->s_children, s_sibling) + if (child_sd->s_type & CONFIGFS_USET_CREATING) + configfs_dir_set_ready(child_sd); +} + +/* + * Check that a directory does not belong to a directory hierarchy being + * attached and not validated yet. + * @sd configfs_dirent of the directory to check + * + * @return non-zero iff the directory was validated + * + * Note: takes configfs_dirent_lock, so the result may change from false to true + * in two consecutive calls, but never from true to false. + */ +int configfs_dirent_is_ready(struct configfs_dirent *sd) +{ + int ret; + + spin_lock(&configfs_dirent_lock); + ret = !(sd->s_type & CONFIGFS_USET_CREATING); + spin_unlock(&configfs_dirent_lock); + + return ret; +} + +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_make_dirent(parent->d_fsdata, dentry, sl, mode, + CONFIGFS_ITEM_LINK); + if (!err) { + err = configfs_create(dentry, mode, init_symlink); + if (err) { + struct configfs_dirent *sd = dentry->d_fsdata; + if (sd) { + spin_lock(&configfs_dirent_lock); + list_del_init(&sd->s_sibling); + spin_unlock(&configfs_dirent_lock); + configfs_put(sd); + } + } + } + return err; +} + +static void remove_dir(struct dentry * d) +{ + struct dentry * parent = dget(d->d_parent); + struct configfs_dirent * sd; + + sd = d->d_fsdata; + spin_lock(&configfs_dirent_lock); + list_del_init(&sd->s_sibling); + spin_unlock(&configfs_dirent_lock); + configfs_put(sd); + if (d_really_is_positive(d)) + simple_rmdir(d_inode(parent),d); + + pr_debug(" o %pd removing done (%d)\n", d, d_count(d)); + + 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. + * + * Caller holds the mutex of the item's inode + */ + +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; + + spin_lock(&configfs_dirent_lock); + dentry->d_fsdata = configfs_get(sd); + sd->s_dentry = dentry; + spin_unlock(&configfs_dirent_lock); + + error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG, + configfs_init_file); + if (error) { + configfs_put(sd); + return error; + } + + d_rehash(dentry); + + return 0; +} + +static struct dentry * configfs_lookup(struct inode *dir, + struct dentry *dentry, + unsigned int flags) +{ + struct configfs_dirent * parent_sd = dentry->d_parent->d_fsdata; + struct configfs_dirent * sd; + int found = 0; + int err; + + /* + * Fake invisibility if dir belongs to a group/default groups hierarchy + * being attached + * + * This forbids userspace to read/write attributes of items which may + * not complete their initialization, since the dentries of the + * attributes won't be instantiated. + */ + err = -ENOENT; + if (!configfs_dirent_is_ready(parent_sd)) + goto out; + + 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. + */ + if (dentry->d_name.len > NAME_MAX) + return ERR_PTR(-ENAMETOOLONG); + d_add(dentry, NULL); + return NULL; + } + +out: + return ERR_PTR(err); +} + +/* + * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are + * attributes and are removed by rmdir(). We recurse, setting + * CONFIGFS_USET_DROPPING on all children that are candidates for + * default detach. + * If there is an error, the caller will reset the flags via + * configfs_detach_rollback(). + */ +static int configfs_detach_prep(struct dentry *dentry, struct mutex **wait_mutex) +{ + struct configfs_dirent *parent_sd = dentry->d_fsdata; + struct configfs_dirent *sd; + int ret; + + /* Mark that we're trying to drop the group */ + parent_sd->s_type |= CONFIGFS_USET_DROPPING; + + 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_element || + (sd->s_type & CONFIGFS_NOT_PINNED)) + continue; + if (sd->s_type & CONFIGFS_USET_DEFAULT) { + /* Abort if racing with mkdir() */ + if (sd->s_type & CONFIGFS_USET_IN_MKDIR) { + if (wait_mutex) + *wait_mutex = &d_inode(sd->s_dentry)->i_mutex; + return -EAGAIN; + } + + /* + * Yup, recursive. If there's a problem, blame + * deep nesting of default_groups + */ + ret = configfs_detach_prep(sd->s_dentry, wait_mutex); + if (!ret) + continue; + } else + ret = -ENOTEMPTY; + + break; + } + +out: + return ret; +} + +/* + * Walk the tree, resetting CONFIGFS_USET_DROPPING wherever it was + * set. + */ +static void configfs_detach_rollback(struct dentry *dentry) +{ + struct configfs_dirent *parent_sd = dentry->d_fsdata; + struct configfs_dirent *sd; + + parent_sd->s_type &= ~CONFIGFS_USET_DROPPING; + + list_for_each_entry(sd, &parent_sd->s_children, s_sibling) + if (sd->s_type & CONFIGFS_USET_DEFAULT) + configfs_detach_rollback(sd->s_dentry); +} + +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; + spin_lock(&configfs_dirent_lock); + list_del_init(&sd->s_sibling); + spin_unlock(&configfs_dirent_lock); + 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; + + mutex_lock(&d_inode(child)->i_mutex); + + configfs_detach_group(sd->s_element); + d_inode(child)->i_flags |= S_DEAD; + dont_mount(child); + + mutex_unlock(&d_inode(child)->i_mutex); + + 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 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; + + ret = -ENOMEM; + child = d_alloc_name(parent, group->cg_item.ci_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 { + BUG_ON(d_inode(child)); + d_drop(child); + dput(child); + } + } + + return ret; +} + +static int populate_groups(struct config_group *group) +{ + struct config_group *new_group; + int ret = 0; + int i; + + if (group->default_groups) { + for (i = 0; group->default_groups[i]; i++) { + new_group = group->default_groups[i]; + + ret = create_default_group(group, new_group); + if (ret) { + detach_groups(group); + break; + } + } + } + + return ret; +} + +/* + * All of link_obj/unlink_obj/link_group/unlink_group require that + * subsys->su_mutex 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; + + /* Drop the reference for ci_entry */ + config_item_put(item); + + /* Drop the reference for ci_parent */ + 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; + + /* + * We hold a reference on the parent for the child's ci_parent + * link. + */ + item->ci_group = config_group_get(to_config_group(parent_item)); + list_add_tail(&item->ci_entry, &item->ci_group->cg_children); + + /* + * We hold a reference on the child for ci_entry on the parent's + * 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) { + /* + * We are going to remove an inode and its dentry but + * the VFS may already have hit and used them. Thus, + * we must lock them as rmdir() would. + */ + mutex_lock(&d_inode(dentry)->i_mutex); + configfs_remove_dir(item); + d_inode(dentry)->i_flags |= S_DEAD; + dont_mount(dentry); + mutex_unlock(&d_inode(dentry)->i_mutex); + d_delete(dentry); + } + } + + return ret; +} + +/* Caller holds the mutex of the item's inode */ +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; + + /* + * FYI, we're faking mkdir in populate_groups() + * We must lock the group's inode to avoid races with the VFS + * which can already hit the inode and try to add/remove entries + * under it. + * + * We must also lock the inode to remove it safely in case of + * error, as rmdir() would. + */ + mutex_lock_nested(&d_inode(dentry)->i_mutex, I_MUTEX_CHILD); + configfs_adjust_dir_dirent_depth_before_populate(sd); + ret = populate_groups(to_config_group(item)); + if (ret) { + configfs_detach_item(item); + d_inode(dentry)->i_flags |= S_DEAD; + dont_mount(dentry); + } + configfs_adjust_dir_dirent_depth_after_populate(sd); + mutex_unlock(&d_inode(dentry)->i_mutex); + if (ret) + d_delete(dentry); + } + + return ret; +} + +/* Caller holds the mutex of the group's inode */ +static void configfs_detach_group(struct config_item *item) +{ + detach_groups(to_config_group(item)); + configfs_detach_item(item); +} + +/* + * After the item has been detached from the filesystem view, we are + * ready to tear it out of the hierarchy. Notify the client before + * we do that so they can perform any cleanup that requires + * navigating the hierarchy. A client does not need to provide this + * callback. The subsystem semaphore MUST be held by the caller, and + * references must be valid for both items. It also assumes the + * caller has validated ci_type. + */ +static void client_disconnect_notify(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->disconnect_notify) + type->ct_group_ops->disconnect_notify(to_config_group(parent_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 ->drop_item() exists, it is responsible for the + * config_item_put(). + */ + 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); +} + +#ifdef DEBUG +static void configfs_dump_one(struct configfs_dirent *sd, int level) +{ + pr_info("%*s\"%s\":\n", level, " ", configfs_get_name(sd)); + +#define type_print(_type) if (sd->s_type & _type) pr_info("%*s %s\n", level, " ", #_type); + type_print(CONFIGFS_ROOT); + type_print(CONFIGFS_DIR); + type_print(CONFIGFS_ITEM_ATTR); + type_print(CONFIGFS_ITEM_LINK); + type_print(CONFIGFS_USET_DIR); + type_print(CONFIGFS_USET_DEFAULT); + type_print(CONFIGFS_USET_DROPPING); +#undef type_print +} + +static int configfs_dump(struct configfs_dirent *sd, int level) +{ + struct configfs_dirent *child_sd; + int ret = 0; + + configfs_dump_one(sd, level); + + if (!(sd->s_type & (CONFIGFS_DIR|CONFIGFS_ROOT))) + return 0; + + list_for_each_entry(child_sd, &sd->s_children, s_sibling) { + ret = configfs_dump(child_sd, level + 2); + if (ret) + break; + } + + return ret; +} +#endif + + +/* + * configfs_depend_item() and configfs_undepend_item() + * + * WARNING: Do not call these from a configfs callback! + * + * This describes these functions and their helpers. + * + * Allow another kernel system to depend on a config_item. If this + * happens, the item cannot go away until the dependent can live without + * it. The idea is to give client modules as simple an interface as + * possible. When a system asks them to depend on an item, they just + * call configfs_depend_item(). If the item is live and the client + * driver is in good shape, we'll happily do the work for them. + * + * Why is the locking complex? Because configfs uses the VFS to handle + * all locking, but this function is called outside the normal + * VFS->configfs path. So it must take VFS locks to prevent the + * VFS->configfs stuff (configfs_mkdir(), configfs_rmdir(), etc). This is + * why you can't call these functions underneath configfs callbacks. + * + * Note, btw, that this can be called at *any* time, even when a configfs + * subsystem isn't registered, or when configfs is loading or unloading. + * Just like configfs_register_subsystem(). So we take the same + * precautions. We pin the filesystem. We lock configfs_dirent_lock. + * If we can find the target item in the + * configfs tree, it must be part of the subsystem tree as well, so we + * do not need the subsystem semaphore. Holding configfs_dirent_lock helps + * locking out mkdir() and rmdir(), who might be racing us. + */ + +/* + * configfs_depend_prep() + * + * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are + * attributes. This is similar but not the same to configfs_detach_prep(). + * Note that configfs_detach_prep() expects the parent to be locked when it + * is called, but we lock the parent *inside* configfs_depend_prep(). We + * do that so we can unlock it if we find nothing. + * + * Here we do a depth-first search of the dentry hierarchy looking for + * our object. + * We deliberately ignore items tagged as dropping since they are virtually + * dead, as well as items in the middle of attachment since they virtually + * do not exist yet. This completes the locking out of racing mkdir() and + * rmdir(). + * Note: subdirectories in the middle of attachment start with s_type = + * CONFIGFS_DIR|CONFIGFS_USET_CREATING set by create_dir(). When + * CONFIGFS_USET_CREATING is set, we ignore the item. The actual set of + * s_type is in configfs_new_dirent(), which has configfs_dirent_lock. + * + * If the target is not found, -ENOENT is bubbled up. + * + * This adds a requirement that all config_items be unique! + * + * This is recursive. There isn't + * much on the stack, though, so folks that need this function - be careful + * about your stack! Patches will be accepted to make it iterative. + */ +static int configfs_depend_prep(struct dentry *origin, + struct config_item *target) +{ + struct configfs_dirent *child_sd, *sd; + int ret = 0; + + BUG_ON(!origin || !origin->d_fsdata); + sd = origin->d_fsdata; + + if (sd->s_element == target) /* Boo-yah */ + goto out; + + list_for_each_entry(child_sd, &sd->s_children, s_sibling) { + if ((child_sd->s_type & CONFIGFS_DIR) && + !(child_sd->s_type & CONFIGFS_USET_DROPPING) && + !(child_sd->s_type & CONFIGFS_USET_CREATING)) { + ret = configfs_depend_prep(child_sd->s_dentry, + target); + if (!ret) + goto out; /* Child path boo-yah */ + } + } + + /* We looped all our children and didn't find target */ + ret = -ENOENT; + +out: + return ret; +} + +int configfs_depend_item(struct configfs_subsystem *subsys, + struct config_item *target) +{ + int ret; + struct configfs_dirent *p, *root_sd, *subsys_sd = NULL; + struct config_item *s_item = &subsys->su_group.cg_item; + struct dentry *root; + + /* + * Pin the configfs filesystem. This means we can safely access + * the root of the configfs filesystem. + */ + root = configfs_pin_fs(); + if (IS_ERR(root)) + return PTR_ERR(root); + + /* + * Next, lock the root directory. We're going to check that the + * subsystem is really registered, and so we need to lock out + * configfs_[un]register_subsystem(). + */ + mutex_lock(&d_inode(root)->i_mutex); + + root_sd = root->d_fsdata; + + list_for_each_entry(p, &root_sd->s_children, s_sibling) { + if (p->s_type & CONFIGFS_DIR) { + if (p->s_element == s_item) { + subsys_sd = p; + break; + } + } + } + + if (!subsys_sd) { + ret = -ENOENT; + goto out_unlock_fs; + } + + /* Ok, now we can trust subsys/s_item */ + + spin_lock(&configfs_dirent_lock); + /* Scan the tree, return 0 if found */ + ret = configfs_depend_prep(subsys_sd->s_dentry, target); + if (ret) + goto out_unlock_dirent_lock; + + /* + * We are sure that the item is not about to be removed by rmdir(), and + * not in the middle of attachment by mkdir(). + */ + p = target->ci_dentry->d_fsdata; + p->s_dependent_count += 1; + +out_unlock_dirent_lock: + spin_unlock(&configfs_dirent_lock); +out_unlock_fs: + mutex_unlock(&d_inode(root)->i_mutex); + + /* + * If we succeeded, the fs is pinned via other methods. If not, + * we're done with it anyway. So release_fs() is always right. + */ + configfs_release_fs(); + + return ret; +} +EXPORT_SYMBOL(configfs_depend_item); + +/* + * Release the dependent linkage. This is much simpler than + * configfs_depend_item() because we know that that the client driver is + * pinned, thus the subsystem is pinned, and therefore configfs is pinned. + */ +void configfs_undepend_item(struct configfs_subsystem *subsys, + struct config_item *target) +{ + struct configfs_dirent *sd; + + /* + * Since we can trust everything is pinned, we just need + * configfs_dirent_lock. + */ + spin_lock(&configfs_dirent_lock); + + sd = target->ci_dentry->d_fsdata; + BUG_ON(sd->s_dependent_count < 1); + + sd->s_dependent_count -= 1; + + /* + * After this unlock, we cannot trust the item to stay alive! + * DO NOT REFERENCE item after this unlock. + */ + spin_unlock(&configfs_dirent_lock); +} +EXPORT_SYMBOL(configfs_undepend_item); + +static int configfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) +{ + int ret = 0; + int module_got = 0; + struct config_group *group = NULL; + struct config_item *item = NULL; + struct config_item *parent_item; + struct configfs_subsystem *subsys; + struct configfs_dirent *sd; + struct config_item_type *type; + struct module *subsys_owner = NULL, *new_item_owner = NULL; + char *name; + + sd = dentry->d_parent->d_fsdata; + + /* + * Fake invisibility if dir belongs to a group/default groups hierarchy + * being attached + */ + if (!configfs_dirent_is_ready(sd)) { + ret = -ENOENT; + goto out; + } + + if (!(sd->s_type & CONFIGFS_USET_DIR)) { + ret = -EPERM; + goto out; + } + + /* Get a working ref for the duration of this function */ + 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)) { + ret = -EPERM; /* Lack-of-mkdir returns -EPERM */ + goto out_put; + } + + /* + * The subsystem may belong to a different module than the item + * being created. We don't want to safely pin the new item but + * fail to pin the subsystem it sits under. + */ + if (!subsys->su_group.cg_item.ci_type) { + ret = -EINVAL; + goto out_put; + } + subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner; + if (!try_module_get(subsys_owner)) { + ret = -EINVAL; + goto out_put; + } + + name = kmalloc(dentry->d_name.len + 1, GFP_KERNEL); + if (!name) { + ret = -ENOMEM; + goto out_subsys_put; + } + + snprintf(name, dentry->d_name.len + 1, "%s", dentry->d_name.name); + + mutex_lock(&subsys->su_mutex); + if (type->ct_group_ops->make_group) { + group = type->ct_group_ops->make_group(to_config_group(parent_item), name); + if (!group) + group = ERR_PTR(-ENOMEM); + if (!IS_ERR(group)) { + link_group(to_config_group(parent_item), group); + item = &group->cg_item; + } else + ret = PTR_ERR(group); + } else { + item = type->ct_group_ops->make_item(to_config_group(parent_item), name); + if (!item) + item = ERR_PTR(-ENOMEM); + if (!IS_ERR(item)) + link_obj(parent_item, item); + else + ret = PTR_ERR(item); + } + mutex_unlock(&subsys->su_mutex); + + kfree(name); + if (ret) { + /* + * If ret != 0, then link_obj() was never called. + * There are no extra references to clean up. + */ + goto out_subsys_put; + } + + /* + * link_obj() has been called (via link_group() for groups). + * From here on out, errors must clean that up. + */ + + type = item->ci_type; + if (!type) { + ret = -EINVAL; + goto out_unlink; + } + + new_item_owner = type->ct_owner; + if (!try_module_get(new_item_owner)) { + ret = -EINVAL; + goto out_unlink; + } + + /* + * I hate doing it this way, but if there is + * an error, module_put() probably should + * happen after any cleanup. + */ + module_got = 1; + + /* + * Make racing rmdir() fail if it did not tag parent with + * CONFIGFS_USET_DROPPING + * Note: if CONFIGFS_USET_DROPPING is already set, attach_group() will + * fail and let rmdir() terminate correctly + */ + spin_lock(&configfs_dirent_lock); + /* This will make configfs_detach_prep() fail */ + sd->s_type |= CONFIGFS_USET_IN_MKDIR; + spin_unlock(&configfs_dirent_lock); + + if (group) + ret = configfs_attach_group(parent_item, item, dentry); + else + ret = configfs_attach_item(parent_item, item, dentry); + + spin_lock(&configfs_dirent_lock); + sd->s_type &= ~CONFIGFS_USET_IN_MKDIR; + if (!ret) + configfs_dir_set_ready(dentry->d_fsdata); + spin_unlock(&configfs_dirent_lock); + +out_unlink: + if (ret) { + /* Tear down everything we built up */ + mutex_lock(&subsys->su_mutex); + + client_disconnect_notify(parent_item, item); + if (group) + unlink_group(group); + else + unlink_obj(item); + client_drop_item(parent_item, item); + + mutex_unlock(&subsys->su_mutex); + + if (module_got) + module_put(new_item_owner); + } + +out_subsys_put: + if (ret) + module_put(subsys_owner); + +out_put: + /* + * link_obj()/link_group() took a reference from child->parent, + * so the parent is safely pinned. We can drop our working + * reference. + */ + config_item_put(parent_item); + +out: + 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 *subsys_owner = NULL, *dead_item_owner = NULL; + int ret; + + sd = dentry->d_fsdata; + if (sd->s_type & CONFIGFS_USET_DEFAULT) + return -EPERM; + + /* Get a working ref until we have the child */ + 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; + } + + /* configfs_mkdir() shouldn't have allowed this */ + BUG_ON(!subsys->su_group.cg_item.ci_type); + subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner; + + /* + * Ensure that no racing symlink() will make detach_prep() fail while + * the new link is temporarily attached + */ + do { + struct mutex *wait_mutex; + + mutex_lock(&configfs_symlink_mutex); + spin_lock(&configfs_dirent_lock); + /* + * Here's where we check for dependents. We're protected by + * configfs_dirent_lock. + * If no dependent, atomically tag the item as dropping. + */ + ret = sd->s_dependent_count ? -EBUSY : 0; + if (!ret) { + ret = configfs_detach_prep(dentry, &wait_mutex); + if (ret) + configfs_detach_rollback(dentry); + } + spin_unlock(&configfs_dirent_lock); + mutex_unlock(&configfs_symlink_mutex); + + if (ret) { + if (ret != -EAGAIN) { + config_item_put(parent_item); + return ret; + } + + /* Wait until the racing operation terminates */ + mutex_lock(wait_mutex); + mutex_unlock(wait_mutex); + } + } while (ret == -EAGAIN); + + /* Get a working ref for the duration of this function */ + item = configfs_get_config_item(dentry); + + /* Drop reference from above, item already holds one. */ + config_item_put(parent_item); + + if (item->ci_type) + dead_item_owner = item->ci_type->ct_owner; + + if (sd->s_type & CONFIGFS_USET_DIR) { + configfs_detach_group(item); + + mutex_lock(&subsys->su_mutex); + client_disconnect_notify(parent_item, item); + unlink_group(to_config_group(item)); + } else { + configfs_detach_item(item); + + mutex_lock(&subsys->su_mutex); + client_disconnect_notify(parent_item, item); + unlink_obj(item); + } + + client_drop_item(parent_item, item); + mutex_unlock(&subsys->su_mutex); + + /* Drop our reference from above */ + config_item_put(item); + + module_put(dead_item_owner); + module_put(subsys_owner); + + return 0; +} + +const struct inode_operations configfs_dir_inode_operations = { + .mkdir = configfs_mkdir, + .rmdir = configfs_rmdir, + .symlink = configfs_symlink, + .unlink = configfs_unlink, + .lookup = configfs_lookup, + .setattr = configfs_setattr, +}; + +const struct inode_operations configfs_root_inode_operations = { + .lookup = configfs_lookup, + .setattr = configfs_setattr, +}; + +#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; + + mutex_lock(&d_inode(parent)->i_mutex); + + new_dentry = lookup_one_len(new_name, parent, strlen(new_name)); + if (!IS_ERR(new_dentry)) { + if (d_really_is_negative(new_dentry)) { + 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); + } + mutex_unlock(&d_inode(parent)->i_mutex); + up_write(&configfs_rename_sem); + + return error; +} +#endif + +static int configfs_dir_open(struct inode *inode, struct file *file) +{ + struct dentry * dentry = file->f_path.dentry; + struct configfs_dirent * parent_sd = dentry->d_fsdata; + int err; + + mutex_lock(&d_inode(dentry)->i_mutex); + /* + * Fake invisibility if dir belongs to a group/default groups hierarchy + * being attached + */ + err = -ENOENT; + if (configfs_dirent_is_ready(parent_sd)) { + file->private_data = configfs_new_dirent(parent_sd, NULL, 0); + if (IS_ERR(file->private_data)) + err = PTR_ERR(file->private_data); + else + err = 0; + } + mutex_unlock(&d_inode(dentry)->i_mutex); + + return err; +} + +static int configfs_dir_close(struct inode *inode, struct file *file) +{ + struct dentry * dentry = file->f_path.dentry; + struct configfs_dirent * cursor = file->private_data; + + mutex_lock(&d_inode(dentry)->i_mutex); + spin_lock(&configfs_dirent_lock); + list_del_init(&cursor->s_sibling); + spin_unlock(&configfs_dirent_lock); + mutex_unlock(&d_inode(dentry)->i_mutex); + + 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 *file, struct dir_context *ctx) +{ + struct dentry *dentry = file->f_path.dentry; + struct super_block *sb = dentry->d_sb; + struct configfs_dirent * parent_sd = dentry->d_fsdata; + struct configfs_dirent *cursor = file->private_data; + struct list_head *p, *q = &cursor->s_sibling; + ino_t ino = 0; + + if (!dir_emit_dots(file, ctx)) + return 0; + if (ctx->pos == 2) { + spin_lock(&configfs_dirent_lock); + list_move(q, &parent_sd->s_children); + spin_unlock(&configfs_dirent_lock); + } + for (p = q->next; p != &parent_sd->s_children; p = p->next) { + struct configfs_dirent *next; + const char *name; + int len; + struct inode *inode = NULL; + + next = list_entry(p, struct configfs_dirent, s_sibling); + if (!next->s_element) + continue; + + name = configfs_get_name(next); + len = strlen(name); + + /* + * We'll have a dentry and an inode for + * PINNED items and for open attribute + * files. We lock here to prevent a race + * with configfs_d_iput() clearing + * s_dentry before calling iput(). + * + * Why do we go to the trouble? If + * someone has an attribute file open, + * the inode number should match until + * they close it. Beyond that, we don't + * care. + */ + spin_lock(&configfs_dirent_lock); + dentry = next->s_dentry; + if (dentry) + inode = d_inode(dentry); + if (inode) + ino = inode->i_ino; + spin_unlock(&configfs_dirent_lock); + if (!inode) + ino = iunique(sb, 2); + + if (!dir_emit(ctx, name, len, ino, dt_type(next))) + return 0; + + spin_lock(&configfs_dirent_lock); + list_move(q, p); + spin_unlock(&configfs_dirent_lock); + p = q; + ctx->pos++; + } + return 0; +} + +static loff_t configfs_dir_lseek(struct file *file, loff_t offset, int whence) +{ + struct dentry * dentry = file->f_path.dentry; + + mutex_lock(&d_inode(dentry)->i_mutex); + switch (whence) { + case 1: + offset += file->f_pos; + case 0: + if (offset >= 0) + break; + default: + mutex_unlock(&d_inode(dentry)->i_mutex); + 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; + + spin_lock(&configfs_dirent_lock); + 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); + spin_unlock(&configfs_dirent_lock); + } + } + mutex_unlock(&d_inode(dentry)->i_mutex); + return offset; +} + +const struct file_operations configfs_dir_operations = { + .open = configfs_dir_open, + .release = configfs_dir_close, + .llseek = configfs_dir_lseek, + .read = generic_read_dir, + .iterate = configfs_readdir, +}; + +int configfs_register_subsystem(struct configfs_subsystem *subsys) +{ + int err; + struct config_group *group = &subsys->su_group; + struct dentry *dentry; + struct dentry *root; + struct configfs_dirent *sd; + + root = configfs_pin_fs(); + if (IS_ERR(root)) + return PTR_ERR(root); + + if (!group->cg_item.ci_name) + group->cg_item.ci_name = group->cg_item.ci_namebuf; + + sd = root->d_fsdata; + link_group(to_config_group(sd->s_element), group); + + mutex_lock_nested(&d_inode(root)->i_mutex, I_MUTEX_PARENT); + + err = -ENOMEM; + dentry = d_alloc_name(root, group->cg_item.ci_name); + if (dentry) { + d_add(dentry, NULL); + + err = configfs_attach_group(sd->s_element, &group->cg_item, + dentry); + if (err) { + BUG_ON(d_inode(dentry)); + d_drop(dentry); + dput(dentry); + } else { + spin_lock(&configfs_dirent_lock); + configfs_dir_set_ready(dentry->d_fsdata); + spin_unlock(&configfs_dirent_lock); + } + } + + mutex_unlock(&d_inode(root)->i_mutex); + + if (err) { + 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; + struct dentry *root = dentry->d_sb->s_root; + + if (dentry->d_parent != root) { + pr_err("Tried to unregister non-subsystem!\n"); + return; + } + + mutex_lock_nested(&d_inode(root)->i_mutex, + I_MUTEX_PARENT); + mutex_lock_nested(&d_inode(dentry)->i_mutex, I_MUTEX_CHILD); + mutex_lock(&configfs_symlink_mutex); + spin_lock(&configfs_dirent_lock); + if (configfs_detach_prep(dentry, NULL)) { + pr_err("Tried to unregister non-empty subsystem!\n"); + } + spin_unlock(&configfs_dirent_lock); + mutex_unlock(&configfs_symlink_mutex); + configfs_detach_group(&group->cg_item); + d_inode(dentry)->i_flags |= S_DEAD; + dont_mount(dentry); + mutex_unlock(&d_inode(dentry)->i_mutex); + + d_delete(dentry); + + mutex_unlock(&d_inode(root)->i_mutex); + + dput(dentry); + + unlink_group(group); + configfs_release_fs(); +} + +EXPORT_SYMBOL(configfs_register_subsystem); +EXPORT_SYMBOL(configfs_unregister_subsystem); |