android_kernel_motorola_sm6225/fs/configfs/dir.c
Louis Rilling 420118caa3 configfs: Rework configfs_depend_item() locking and make lockdep happy
configfs_depend_item() recursively locks all inodes mutex from configfs root to
the target item, which makes lockdep unhappy. The purpose of this recursive
locking is to ensure that the item tree can be safely parsed and that the target
item, if found, is not about to leave.

This patch reworks configfs_depend_item() locking using configfs_dirent_lock.
Since configfs_dirent_lock protects all changes to the configfs_dirent tree, and
protects tagging of items to be removed, this lock can be used instead of the
inodes mutex lock chain.
This needs that the check for dependents be done atomically with
CONFIGFS_USET_DROPPING tagging.

Now lockdep looks happy with configfs.

[ Lifted the setting of s_type into configfs_new_dirent() to satisfy the
  atomic setting of CONFIGFS_USET_CREATING  -- Joel ]

Signed-off-by: Louis Rilling <louis.rilling@kerlabs.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
2009-04-30 10:48:26 -07:00

1741 lines
44 KiB
C

/* -*- 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) {
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 const struct dentry_operations configfs_dentry_ops = {
.d_iput = configfs_d_iput,
/* simple_delete_dentry() isn't exported */
.d_delete = configfs_d_delete,
};
#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);
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) */
inc_nlink(inode);
return 0;
}
static int configfs_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_dirent_exists(p->d_fsdata, d->d_name.name);
if (!error)
error = configfs_make_dirent(p->d_fsdata, d, k, mode,
CONFIGFS_DIR | CONFIGFS_USET_CREATING);
if (!error) {
configfs_set_dir_dirent_depth(p->d_fsdata, d->d_fsdata);
error = configfs_create(d, mode, init_dir);
if (!error) {
inc_nlink(p->d_inode);
(d)->d_op = &configfs_dentry_ops;
} else {
struct configfs_dirent *sd = d->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;
}
/**
* 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)
{
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;
}
/*
* 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)
dentry->d_op = &configfs_dentry_ops;
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 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->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.
*
* 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;
dentry->d_fsdata = configfs_get(sd);
sd->s_dentry = dentry;
error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG,
configfs_init_file);
if (error) {
configfs_put(sd);
return error;
}
dentry->d_op = &configfs_dentry_ops;
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;
/*
* 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.
*/
return simple_lookup(dir, dentry, nd);
}
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 = &sd->s_dentry->d_inode->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(&child->d_inode->i_mutex);
configfs_detach_group(sd->s_element);
child->d_inode->i_flags |= S_DEAD;
mutex_unlock(&child->d_inode->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 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;
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(&dentry->d_inode->i_mutex);
configfs_remove_dir(item);
dentry->d_inode->i_flags |= S_DEAD;
mutex_unlock(&dentry->d_inode->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(&dentry->d_inode->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);
dentry->d_inode->i_flags |= S_DEAD;
}
configfs_adjust_dir_dirent_depth_after_populate(sd);
mutex_unlock(&dentry->d_inode->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)
{
printk(KERN_INFO "%*s\"%s\":\n", level, " ", configfs_get_name(sd));
#define type_print(_type) if (sd->s_type & _type) printk(KERN_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 dependant 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 = origin->d_fsdata;
int ret = 0;
BUG_ON(!origin || !sd);
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;
/*
* Pin the configfs filesystem. This means we can safely access
* the root of the configfs filesystem.
*/
ret = configfs_pin_fs();
if (ret)
return ret;
/*
* 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(&configfs_sb->s_root->d_inode->i_mutex);
root_sd = configfs_sb->s_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(&configfs_sb->s_root->d_inode->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, int 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;
if (dentry->d_parent == configfs_sb->s_root) {
ret = -EPERM;
goto out;
}
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;
if (dentry->d_parent == configfs_sb->s_root)
return -EPERM;
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,
};
#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(&parent->d_inode->i_mutex);
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);
}
mutex_unlock(&parent->d_inode->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(&dentry->d_inode->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(&dentry->d_inode->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(&dentry->d_inode->i_mutex);
spin_lock(&configfs_dirent_lock);
list_del_init(&cursor->s_sibling);
spin_unlock(&configfs_dirent_lock);
mutex_unlock(&dentry->d_inode->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 * filp, void * dirent, filldir_t filldir)
{
struct dentry *dentry = filp->f_path.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) {
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;
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;
spin_lock(&configfs_dirent_lock);
list_move(q, p);
spin_unlock(&configfs_dirent_lock);
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_path.dentry;
mutex_lock(&dentry->d_inode->i_mutex);
switch (origin) {
case 1:
offset += file->f_pos;
case 0:
if (offset >= 0)
break;
default:
mutex_unlock(&file->f_path.dentry->d_inode->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(&dentry->d_inode->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,
.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);
mutex_lock_nested(&configfs_sb->s_root->d_inode->i_mutex,
I_MUTEX_PARENT);
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) {
d_add(dentry, NULL);
err = configfs_attach_group(sd->s_element, &group->cg_item,
dentry);
if (err) {
d_delete(dentry);
dput(dentry);
} else {
spin_lock(&configfs_dirent_lock);
configfs_dir_set_ready(dentry->d_fsdata);
spin_unlock(&configfs_dirent_lock);
}
}
mutex_unlock(&configfs_sb->s_root->d_inode->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;
if (dentry->d_parent != configfs_sb->s_root) {
printk(KERN_ERR "configfs: Tried to unregister non-subsystem!\n");
return;
}
mutex_lock_nested(&configfs_sb->s_root->d_inode->i_mutex,
I_MUTEX_PARENT);
mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
mutex_lock(&configfs_symlink_mutex);
spin_lock(&configfs_dirent_lock);
if (configfs_detach_prep(dentry, NULL)) {
printk(KERN_ERR "configfs: Tried to unregister non-empty subsystem!\n");
}
spin_unlock(&configfs_dirent_lock);
mutex_unlock(&configfs_symlink_mutex);
configfs_detach_group(&group->cg_item);
dentry->d_inode->i_flags |= S_DEAD;
mutex_unlock(&dentry->d_inode->i_mutex);
d_delete(dentry);
mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);
dput(dentry);
unlink_group(group);
configfs_release_fs();
}
EXPORT_SYMBOL(configfs_register_subsystem);
EXPORT_SYMBOL(configfs_unregister_subsystem);