mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-29 04:09:39 +00:00
![Junxiao Bi](/assets/img/avatar_default.png)
A race window in configfs, it starts from one dentry is UNHASHED and end before configfs_d_iput is called. In this window, if a lookup happen, since the original dentry was UNHASHED, so a new dentry will be allocated, and then in configfs_attach_attr(), sd->s_dentry will be updated to the new dentry. Then in configfs_d_iput(), BUG_ON(sd->s_dentry != dentry) will be triggered and system panic. sys_open: sys_close: ... fput dput dentry_kill __d_drop <--- dentry unhashed here, but sd->dentry still point to this dentry. lookup_real configfs_lookup configfs_attach_attr---> update sd->s_dentry to new allocated dentry here. d_kill configfs_d_iput <--- BUG_ON(sd->s_dentry != dentry) triggered here. To fix it, change configfs_d_iput to not update sd->s_dentry if sd->s_count > 2, that means there are another dentry is using the sd beside the one that is going to be put. Use configfs_dirent_lock in configfs_attach_attr to sync with configfs_d_iput. With the following steps, you can reproduce the bug. 1. enable ocfs2, this will mount configfs at /sys/kernel/config and fill configure in it. 2. run the following script. while [ 1 ]; do cat /sys/kernel/config/cluster/$your_cluster_name/idle_timeout_ms > /dev/null; done & while [ 1 ]; do cat /sys/kernel/config/cluster/$your_cluster_name/idle_timeout_ms > /dev/null; done & Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1732 lines
44 KiB
C
1732 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) {
|
|
/* 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 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 *d)
|
|
{
|
|
int error;
|
|
umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
|
|
struct dentry *p = d->d_parent;
|
|
|
|
BUG_ON(!k);
|
|
|
|
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);
|
|
} 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)
|
|
{
|
|
int error = create_dir(item, 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) {
|
|
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, 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 = &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;
|
|
dont_mount(child);
|
|
|
|
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 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(child->d_inode);
|
|
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(&dentry->d_inode->i_mutex);
|
|
configfs_remove_dir(item);
|
|
dentry->d_inode->i_flags |= S_DEAD;
|
|
dont_mount(dentry);
|
|
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;
|
|
dont_mount(dentry);
|
|
}
|
|
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 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(&root->d_inode->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(&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, 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(&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 *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 = dentry->d_inode;
|
|
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(&dentry->d_inode->i_mutex);
|
|
switch (whence) {
|
|
case 1:
|
|
offset += file->f_pos;
|
|
case 0:
|
|
if (offset >= 0)
|
|
break;
|
|
default:
|
|
mutex_unlock(&file_inode(file)->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,
|
|
.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(&root->d_inode->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(dentry->d_inode);
|
|
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(&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;
|
|
struct dentry *root = dentry->d_sb->s_root;
|
|
|
|
if (dentry->d_parent != root) {
|
|
printk(KERN_ERR "configfs: Tried to unregister non-subsystem!\n");
|
|
return;
|
|
}
|
|
|
|
mutex_lock_nested(&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;
|
|
dont_mount(dentry);
|
|
mutex_unlock(&dentry->d_inode->i_mutex);
|
|
|
|
d_delete(dentry);
|
|
|
|
mutex_unlock(&root->d_inode->i_mutex);
|
|
|
|
dput(dentry);
|
|
|
|
unlink_group(group);
|
|
configfs_release_fs();
|
|
}
|
|
|
|
EXPORT_SYMBOL(configfs_register_subsystem);
|
|
EXPORT_SYMBOL(configfs_unregister_subsystem);
|