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    From
    Subject[RFC][PATCH 3 of 4] Configfs is really sysfs
    Date
    Configfs rewritten as a single file and updated to use kobjects instead of its
    own clone of kobjects (config_items).

    diff -up --recursive 2.6.13-rc5-mm1.clean/fs/configfs/Makefile 2.6.13-rc5-mm1/fs/configfs/Makefile
    --- 2.6.13-rc5-mm1.clean/fs/configfs/Makefile 2005-08-09 18:23:30.000000000 -0400
    +++ 2.6.13-rc5-mm1/fs/configfs/Makefile 2005-08-29 17:26:02.000000000 -0400
    @@ -2,6 +2,5 @@
    # Makefile for the configfs virtual filesystem
    #

    -obj-$(CONFIG_CONFIGFS_FS) += configfs.o
    +obj-$(CONFIG_CONFIGFS_FS) += configfs.o ddbond.config.o

    -configfs-objs := inode.o file.o dir.o symlink.o mount.o item.o
    diff -up --recursive 2.6.13-rc5-mm1.clean/fs/configfs/configfs.c 2.6.13-rc5-mm1/fs/configfs/configfs.c
    --- 2.6.13-rc5-mm1.clean/fs/configfs/configfs.c 2005-08-30 17:50:30.000000000 -0400
    +++ 2.6.13-rc5-mm1/fs/configfs/configfs.c 2005-08-29 21:36:47.000000000 -0400
    @@ -0,0 +1,1897 @@
    +/*
    + * Based on sysfs:
    + * sysfs Copyright (C) 2001, 2002, 2003 Patrick Mochel
    + *
    + * configfs Copyright (C) 2005 Oracle. All rights reserved.
    + */
    +
    +#include <linux/fs.h>
    +#include <linux/namei.h>
    +#include <linux/module.h>
    +#include <linux/mount.h>
    +#include <linux/backing-dev.h>
    +#include <linux/pagemap.h>
    +#include <linux/configfs.h>
    +
    +#define CONFIGFS_ROOT 0x0001
    +#define CONFIGFS_DIR 0x0002
    +#define CONFIGFS_ITEM_ATTR 0x0004
    +#define CONFIGFS_ITEM_LINK 0x0020
    +#define CONFIGFS_USET_DIR 0x0040
    +#define CONFIGFS_USET_DEFAULT 0x0080
    +#define CONFIGFS_USET_DROPPING 0x0100
    +#define CONFIGFS_NOT_PINNED (CONFIGFS_ITEM_ATTR)
    +
    +struct sysfs_symlink {
    + struct list_head sl_list;
    + struct kobject *sl_target;
    +};
    +
    +static inline struct kobject *to_kobj(struct dentry *dentry)
    +{
    + struct sysfs_dirent *sd = dentry->d_fsdata;
    + return ((struct kobject *)sd->s_element);
    +}
    +
    +static inline struct attribute *to_attr(struct dentry *dentry)
    +{
    + struct sysfs_dirent *sd = dentry->d_fsdata;
    + return ((struct attribute *)sd->s_element);
    +}
    +
    +static inline struct kobject *sysfs_get_kobject(struct dentry *dentry)
    +{
    + struct kobject *kobj = NULL;
    +
    + spin_lock(&dcache_lock);
    + if (!d_unhashed(dentry)) {
    + struct sysfs_dirent *sd = dentry->d_fsdata;
    + if (sd->s_type & CONFIGFS_ITEM_LINK) {
    + struct sysfs_symlink *sl = sd->s_element;
    + kobj = kobject_get(sl->sl_target);
    + } else
    + kobj = kobject_get(sd->s_element);
    + }
    + spin_unlock(&dcache_lock);
    +
    + return kobj;
    +}
    +
    +static kmem_cache_t *sysfs_dir_cachep;
    +
    +static void release_sysfs_dirent(struct sysfs_dirent *sd)
    +{
    + if ((sd->s_type & CONFIGFS_ROOT))
    + return;
    + kmem_cache_free(sysfs_dir_cachep, sd);
    +}
    +
    +static struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd)
    +{
    + if (sd) {
    + WARN_ON(!atomic_read(&sd->s_count));
    + atomic_inc(&sd->s_count);
    + }
    + return sd;
    +}
    +
    +static void sysfs_put(struct sysfs_dirent *sd)
    +{
    + WARN_ON(!atomic_read(&sd->s_count));
    + if (atomic_dec_and_test(&sd->s_count))
    + release_sysfs_dirent(sd);
    +}
    +
    +/*
    + * inode.c - basic inode and dentry operations.
    + */
    +
    +static struct super_block *sysfs_sb;
    +
    +static struct address_space_operations sysfs_aops = {
    + .readpage = simple_readpage,
    + .prepare_write = simple_prepare_write,
    + .commit_write = simple_commit_write
    +};
    +
    +static struct backing_dev_info sysfs_backing_dev_info = {
    + .ra_pages = 0, /* No readahead */
    + .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
    +};
    +
    +static struct inode *sysfs_new_inode(mode_t mode)
    +{
    + struct inode *inode = new_inode(sysfs_sb);
    + if (inode) {
    + inode->i_blksize = PAGE_CACHE_SIZE;
    + inode->i_blocks = 0;
    + inode->i_mode = mode;
    + inode->i_uid = 0;
    + inode->i_gid = 0;
    + inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
    + inode->i_mapping->a_ops = &sysfs_aops;
    + inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
    + }
    + return inode;
    +}
    +
    +static int sysfs_create(struct dentry *dentry, int mode, int (*init) (struct inode *))
    +{
    + int error = 0;
    + struct inode *inode = NULL;
    + if (dentry) {
    + if (!dentry->d_inode) {
    + if ((inode = sysfs_new_inode(mode))) {
    + if (dentry->d_parent
    + && dentry->d_parent->d_inode) {
    + struct inode *p_inode =
    + dentry->d_parent->d_inode;
    + p_inode->i_mtime = p_inode->i_ctime =
    + CURRENT_TIME;
    + }
    + goto Proceed;
    + } else
    + error = -ENOMEM;
    + } else
    + error = -EEXIST;
    + } else
    + error = -ENOENT;
    + goto Done;
    +
    + Proceed:
    + if (init)
    + error = init(inode);
    + if (!error) {
    + d_instantiate(dentry, inode);
    + if (S_ISDIR(mode) || S_ISLNK(mode)) /* pin link and directory dentries */
    + dget(dentry);
    + } else
    + iput(inode);
    + Done:
    + return error;
    +}
    +
    +/*
    + * Get the name for corresponding element represented by the given sysfs_dirent
    + */
    +static const unsigned char *sysfs_get_name(struct sysfs_dirent *sd)
    +{
    + if (!sd || !sd->s_element)
    + BUG();
    +
    + /* These always have a dentry, so use that */
    + if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
    + return sd->s_dentry->d_name.name;
    +
    + if (sd->s_type & CONFIGFS_ITEM_ATTR)
    + return ((struct attribute *)sd->s_element)->name;
    + return NULL;
    +}
    +
    +/*
    + * Unhashes the dentry corresponding to given sysfs_dirent
    + * Called with parent inode's i_sem held.
    + */
    +static void sysfs_drop_dentry(struct sysfs_dirent *sd, struct dentry *parent)
    +{
    + struct dentry *dentry = sd->s_dentry;
    +
    + if (dentry) {
    + spin_lock(&dcache_lock);
    + if (!(d_unhashed(dentry) && dentry->d_inode)) {
    + dget_locked(dentry);
    + __d_drop(dentry);
    + spin_unlock(&dcache_lock);
    + simple_unlink(parent->d_inode, dentry);
    + } else {
    + spin_unlock(&dcache_lock);
    + }
    + }
    +}
    +
    +#if 0
    +static void sysfs_hash_and_remove(struct dentry *dir, const char *name)
    +{
    + struct sysfs_dirent *sd;
    + struct sysfs_dirent *parent_sd = dir->d_fsdata;
    +
    + down(&dir->d_inode->i_sem);
    + list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
    + if (!sd->s_element)
    + continue;
    + if (!strcmp(sysfs_get_name(sd), name)) {
    + list_del_init(&sd->s_sibling);
    + sysfs_drop_dentry(sd, dir);
    + sysfs_put(sd);
    + break;
    + }
    + }
    + up(&dir->d_inode->i_sem);
    +}
    +#endif
    +
    +static struct kset sysfs_root_group = {
    + .kobj = {
    + .name = "root",
    + .k_name = sysfs_root_group.kobj.name,
    + },
    +};
    +
    +static int is_root(struct kobject *kobj)
    +{
    + return kobj == &sysfs_root_group.kobj;
    +}
    +
    +/*
    + * symlink.c - operations for sysfs symlinks.
    + */
    +
    +static int object_depth(struct kobject *kobj)
    +{
    + struct kobject *p = kobj;
    + int depth = 0;
    + do {
    + depth++;
    + } while ((p = p->parent) && !is_root(p));
    + return depth;
    +}
    +
    +static int object_path_length(struct kobject *kobj)
    +{
    + struct kobject *p = kobj;
    + int length = 1;
    + do {
    + length += strlen(kobject_name(p)) + 1;
    + p = p->parent;
    + } while (p && !is_root(p));
    + return length;
    +}
    +
    +static void fill_object_path(struct kobject *kobj, char *buffer, int length)
    +{
    + struct kobject *p;
    +
    + --length;
    + for (p = kobj; p && !is_root(p); p = p->parent) {
    + int cur = strlen(kobject_name(p));
    +
    + /* back up enough to print this bus id with '/' */
    + length -= cur;
    + strncpy(buffer + length, kobject_name(p), cur);
    + *(buffer + --length) = '/';
    + }
    +}
    +
    +static int sysfs_get_target_path(struct kobject *kobj, struct kobject *target, char *path)
    +{
    + char *s;
    + int depth, size;
    +
    + depth = object_depth(kobj);
    + size = object_path_length(target) + depth * 3 - 1;
    + if (size > PATH_MAX)
    + return -ENAMETOOLONG;
    +
    + pr_debug("%s: depth = %d, size = %d\n", __FUNCTION__, depth, size);
    +
    + for (s = path; depth--; s += 3)
    + strcpy(s, "../");
    +
    + fill_object_path(target, path, size);
    + pr_debug("%s: path = '%s'\n", __FUNCTION__, path);
    +
    + return 0;
    +}
    +
    +static DECLARE_RWSEM(sysfs_rename_sem);
    +
    +static int sysfs_getlink(struct dentry *dentry, char *path)
    +{
    + struct kobject *kobj, *sl_target;
    + int error = 0;
    +
    + kobj = sysfs_get_kobject(dentry->d_parent);
    + if (!kobj)
    + return -EINVAL;
    +
    + sl_target = sysfs_get_kobject(dentry);
    + if (!sl_target) {
    + kobject_put(kobj);
    + return -EINVAL;
    + }
    +
    + down_read(&sysfs_rename_sem);
    + error = sysfs_get_target_path(kobj, sl_target, path);
    + up_read(&sysfs_rename_sem);
    +
    + kobject_put(kobj);
    + kobject_put(sl_target);
    + return error;
    +
    +}
    +
    +static int sysfs_follow_link(struct dentry *dentry, struct nameidata *nd)
    +{
    + int error = -ENOMEM;
    + unsigned long page = get_zeroed_page(GFP_KERNEL);
    + if (page)
    + error = sysfs_getlink(dentry, (char *)page);
    + nd_set_link(nd, error ? ERR_PTR(error) : (char *)page);
    + return 0;
    +}
    +
    +static void sysfs_put_link(struct dentry *dentry, struct nameidata *nd)
    +{
    + char *page = nd_get_link(nd);
    + if (!IS_ERR(page))
    + free_page((unsigned long)page);
    +}
    +
    +static struct inode_operations sysfs_symlink_inode_operations = {
    + .readlink = generic_readlink,
    + .follow_link = sysfs_follow_link,
    + .put_link = sysfs_put_link,
    +};
    +
    +static int init_symlink(struct inode *inode)
    +{
    + inode->i_op = &sysfs_symlink_inode_operations;
    + return 0;
    +}
    +
    +/*
    + * file.c - operations for regular (text) files.
    + */
    +
    +struct sysfs_buffer {
    + size_t count;
    + loff_t pos;
    + char *page;
    + struct sysfs_ops *ops;
    + struct semaphore sem;
    + int needs_read_fill;
    +};
    +
    +/*
    + * Allocate @buffer->page, if it hasn't been already, then call the
    + * kobject's show() method to fill the buffer with this attribute's
    + * data. This is called only once, on the file's first read.
    + */
    +static int fill_read_buffer(struct dentry *dentry, struct sysfs_buffer *buffer)
    +{
    + struct attribute *attr = to_attr(dentry);
    + struct kobject *kobj = to_kobj(dentry->d_parent);
    + struct sysfs_ops *ops = buffer->ops;
    + int ret = 0;
    + ssize_t count;
    +
    + if (!buffer->page)
    + buffer->page = (char *)get_zeroed_page(GFP_KERNEL);
    + if (!buffer->page)
    + return -ENOMEM;
    +
    + count = ops->show(kobj, attr, buffer->page);
    + buffer->needs_read_fill = 0;
    + BUG_ON(count > (ssize_t) PAGE_SIZE);
    + if (count >= 0)
    + buffer->count = count;
    + else
    + ret = count;
    + return ret;
    +}
    +
    +/*
    + * Copy the buffer we filled in fill_read_buffer() to userspace.
    + * This is done at the reader's leisure, copying and advancing
    + * the amount they specify each time.
    + * This may be called continuously until the buffer is empty.
    + */
    +static int flush_read_buffer(struct sysfs_buffer *buffer, char __user *buf,
    + size_t count, loff_t *ppos)
    +{
    + int error;
    +
    + if (*ppos > buffer->count)
    + return 0;
    +
    + if (count > (buffer->count - *ppos))
    + count = buffer->count - *ppos;
    +
    + error = copy_to_user(buf, buffer->page + *ppos, count);
    + if (!error)
    + *ppos += count;
    + return error ? -EFAULT : count;
    +}
    +
    +/*
    + * Allocate @buffer->page if it hasn't been already, then
    + * copy the user-supplied buffer into it.
    + */
    +static int fill_write_buffer(struct sysfs_buffer *buffer, const char __user *buf,
    + size_t count)
    +{
    + int error;
    +
    + if (!buffer->page)
    + buffer->page = (char *)get_zeroed_page(GFP_KERNEL);
    + if (!buffer->page)
    + return -ENOMEM;
    +
    + if (count > PAGE_SIZE)
    + count = PAGE_SIZE;
    + error = copy_from_user(buffer->page, buf, count);
    + buffer->needs_read_fill = 1;
    + return error ? -EFAULT : count;
    +}
    +
    +/*
    + * Get the correct pointers for the kobject and the attribute we're
    + * dealing with, then call the store method for the attribute,
    + * passing the buffer that we acquired in fill_write_buffer().
    + */
    +static int flush_write_buffer(struct dentry *dentry, struct sysfs_buffer *buffer,
    + size_t count)
    +{
    + struct attribute *attr = to_attr(dentry);
    + struct kobject *kobj = to_kobj(dentry->d_parent);
    + struct sysfs_ops *ops = buffer->ops;
    +
    + return ops->store(kobj, attr, buffer->page, count);
    +}
    +
    +static int check_perm(struct inode *inode, struct file *file)
    +{
    + struct kobject *kobj = sysfs_get_kobject(file->f_dentry->d_parent);
    + struct attribute *attr = to_attr(file->f_dentry);
    + struct sysfs_buffer *buffer;
    + struct sysfs_ops *ops = NULL;
    + int error = 0;
    +
    + if (!kobj || !attr)
    + goto Einval;
    +
    + /* Grab the module reference for this attribute if we have one */
    + if (!try_module_get(attr->owner)) {
    + error = -ENODEV;
    + goto Done;
    + }
    +
    + if (!kobj->ktype)
    + goto Eaccess;
    +
    + ops = kobj->ktype->sysfs_ops;
    +
    + /* File needs write support.
    + * The inode's perms must say it's ok, and we must have a store method.
    + */
    + if (file->f_mode & FMODE_WRITE) {
    +
    + if (!(inode->i_mode & S_IWUGO) || !ops->store)
    + goto Eaccess;
    +
    + }
    +
    + /* File needs read support.
    + * The inode's perms must say it's ok, and we there
    + * must be a show method for it.
    + */
    + if (file->f_mode & FMODE_READ) {
    + if (!(inode->i_mode & S_IRUGO) || !ops->show)
    + goto Eaccess;
    + }
    +
    + /* No error? Great, allocate a buffer for the file, and store it
    + * it in file->private_data for easy access.
    + */
    + buffer = kmalloc(sizeof(struct sysfs_buffer), GFP_KERNEL);
    + if (buffer) {
    + memset(buffer, 0, sizeof(struct sysfs_buffer));
    + init_MUTEX(&buffer->sem);
    + buffer->needs_read_fill = 1;
    + buffer->ops = ops;
    + file->private_data = buffer;
    + } else
    + error = -ENOMEM;
    + goto Done;
    +
    + Einval:
    + error = -EINVAL;
    + goto Done;
    + Eaccess:
    + error = -EACCES;
    + module_put(attr->owner);
    + Done:
    + if (error && kobj)
    + kobject_put(kobj);
    + return error;
    +}
    +
    +/*
    + * Userspace wants to read an attribute file. The attribute descriptor
    + * is in the file's ->d_fsdata. The target object is in the directory's
    + * ->d_fsdata.
    + *
    + * We call fill_read_buffer() to allocate and fill the buffer from the
    + * object's show() method exactly once (if the read is happening from
    + * the beginning of the file). That should fill the entire buffer with
    + * all the data the object has to offer for that attribute.
    + * We then call flush_read_buffer() to copy the buffer to userspace
    + * in the increments specified.
    + */
    +static ssize_t sysfs_read_file(struct file *file, char __user *buf,
    + size_t count, loff_t *ppos)
    +{
    + struct sysfs_buffer *buffer = file->private_data;
    + ssize_t retval = 0;
    +
    + down(&buffer->sem);
    + if (buffer->needs_read_fill) {
    + if ((retval = fill_read_buffer(file->f_dentry, buffer)))
    + goto out;
    + }
    + pr_debug("%s: count = %d, ppos = %lld, buf = %s\n",
    + __FUNCTION__, count, *ppos, buffer->page);
    + retval = flush_read_buffer(buffer, buf, count, ppos);
    + out:
    + up(&buffer->sem);
    + return retval;
    +}
    +
    +/*
    + * Similar to sysfs_read_file(), though working in the opposite direction.
    + * We allocate and fill the data from the user in fill_write_buffer(),
    + * then push it to the kobject in flush_write_buffer().
    + * There is no easy way for us to know if userspace is only doing a partial
    + * write, so we don't support them. We expect the entire buffer to come
    + * on the first write.
    + * Hint: if you're writing a value, first read the file, modify only the
    + * the value you're changing, then write entire buffer back.
    + */
    +static ssize_t sysfs_write_file(struct file *file, const char __user *buf,
    + size_t count, loff_t *ppos)
    +{
    + struct sysfs_buffer *buffer = file->private_data;
    +
    + down(&buffer->sem);
    + count = fill_write_buffer(buffer, buf, count);
    + if (count > 0)
    + count = flush_write_buffer(file->f_dentry, buffer, count);
    + if (count > 0)
    + *ppos += count;
    + up(&buffer->sem);
    + return count;
    +}
    +
    +static int sysfs_open_file(struct inode *inode, struct file *filp)
    +{
    + return check_perm(inode, filp);
    +}
    +
    +static int sysfs_release(struct inode *inode, struct file *filp)
    +{
    + struct kobject *kobj = to_kobj(filp->f_dentry->d_parent);
    + struct attribute *attr = to_attr(filp->f_dentry);
    + struct module *owner = attr->owner;
    + struct sysfs_buffer *buffer = filp->private_data;
    +
    + if (kobj)
    + kobject_put(kobj);
    + /* After this point, attr should not be accessed. */
    + module_put(owner);
    +
    + if (buffer) {
    + if (buffer->page)
    + free_page((unsigned long)buffer->page);
    + kfree(buffer);
    + }
    + return 0;
    +}
    +
    +static struct file_operations sysfs_file_operations = {
    + .read = sysfs_read_file,
    + .write = sysfs_write_file,
    + .llseek = generic_file_llseek,
    + .open = sysfs_open_file,
    + .release = sysfs_release,
    +};
    +
    +static int init_file(struct inode *inode)
    +{
    + inode->i_size = PAGE_SIZE;
    + inode->i_fop = &sysfs_file_operations;
    + return 0;
    +}
    +
    +static void sysfs_d_iput(struct dentry *dentry, struct inode *inode)
    +{
    + struct sysfs_dirent *sd = dentry->d_fsdata;
    +
    + if (sd) {
    + BUG_ON(sd->s_dentry != dentry);
    + sd->s_dentry = NULL;
    + sysfs_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 sysfs_d_delete(struct dentry *dentry)
    +{
    + return 1;
    +}
    +
    +static struct dentry_operations sysfs_dentry_ops = {
    + .d_iput = sysfs_d_iput,
    + .d_delete = sysfs_d_delete,
    +};
    +
    +/*
    + * Allocates a new sysfs_dirent and links it to the parent sysfs_dirent
    + */
    +static struct sysfs_dirent *sysfs_new_dirent(struct sysfs_dirent *parent_sd,
    + void *element)
    +{
    + struct sysfs_dirent *sd;
    +
    + sd = kmem_cache_alloc(sysfs_dir_cachep, GFP_KERNEL);
    + if (!sd)
    + return NULL;
    +
    + memset(sd, 0, sizeof(*sd));
    + atomic_set(&sd->s_count, 1);
    + INIT_LIST_HEAD(&sd->s_links);
    + INIT_LIST_HEAD(&sd->s_children);
    + list_add(&sd->s_sibling, &parent_sd->s_children);
    + sd->s_element = element;
    +
    + return sd;
    +}
    +
    +static int sysfs_make_dirent(struct sysfs_dirent *parent_sd, struct dentry *dentry,
    + void *element, umode_t mode, int type)
    +{
    + struct sysfs_dirent *sd;
    +
    + sd = sysfs_new_dirent(parent_sd, element);
    + if (!sd)
    + return -ENOMEM;
    +
    + sd->s_mode = mode;
    + sd->s_type = type;
    + sd->s_dentry = dentry;
    + if (dentry) {
    + dentry->d_fsdata = sysfs_get(sd);
    + dentry->d_op = &sysfs_dentry_ops;
    + }
    +
    + return 0;
    +}
    +
    +static int sysfs_add_file(struct dentry *dir, const struct attribute *attr, int type)
    +{
    + struct sysfs_dirent *parent_sd = dir->d_fsdata;
    + umode_t mode = (attr->mode & S_IALLUGO) | S_IFREG;
    + int error = 0;
    +
    + down(&dir->d_inode->i_sem);
    + error = sysfs_make_dirent(parent_sd, NULL, (void *)attr, mode, type);
    + up(&dir->d_inode->i_sem);
    +
    + return error;
    +}
    +
    +static int configfs_create_file(struct kobject *kobj, const struct attribute *attr)
    +{
    + BUG_ON(!kobj || !kobj->dentry || !attr);
    +
    + return sysfs_add_file(kobj->dentry, attr, CONFIGFS_ITEM_ATTR);
    +}
    +
    +static int configfs_add_link(struct sysfs_symlink *sl, struct dentry *parent, struct dentry *dentry)
    +{
    + int err = 0;
    + umode_t mode = S_IFLNK | S_IRWXUGO;
    +
    + err = sysfs_create(dentry, mode, init_symlink);
    + if (!err) {
    + err = sysfs_make_dirent(parent->d_fsdata, dentry, sl,
    + mode, CONFIGFS_ITEM_LINK);
    + if (!err)
    + dentry->d_op = &sysfs_dentry_ops;
    + }
    + return err;
    +}
    +
    +static int create_link(struct kobject *parent_kobj, struct kobject *kobj, struct dentry *dentry)
    +{
    + struct sysfs_dirent *target_sd = kobj->dentry->d_fsdata;
    + struct sysfs_symlink *sl;
    + int ret;
    +
    + ret = -ENOMEM;
    + sl = kmalloc(sizeof(struct sysfs_symlink), GFP_KERNEL);
    + if (sl) {
    + sl->sl_target = kobject_get(kobj);
    + /* FIXME: needs a lock, I'd bet */
    + list_add(&sl->sl_list, &target_sd->s_links);
    + ret = configfs_add_link(sl, parent_kobj->dentry, dentry);
    + if (ret) {
    + list_del_init(&sl->sl_list);
    + kobject_put(kobj);
    + kfree(sl);
    + }
    + }
    +
    + return ret;
    +}
    +
    +static int get_target(const char *symname, struct nameidata *nd, struct kobject **target)
    +{
    + int ret;
    +
    + ret = path_lookup(symname, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, nd);
    + if (!ret) {
    + if (nd->dentry->d_sb == sysfs_sb) {
    + *target = sysfs_get_kobject(nd->dentry);
    + if (!*target) {
    + ret = -ENOENT;
    + path_release(nd);
    + }
    + } else
    + ret = -EPERM;
    + }
    +
    + return ret;
    +}
    +
    +/*
    + * dir.c - Operations for directories.
    + */
    +
    +static int sysfs_dir_open(struct inode *inode, struct file *file)
    +{
    + struct dentry *dentry = file->f_dentry;
    + struct sysfs_dirent *parent_sd = dentry->d_fsdata;
    +
    + down(&dentry->d_inode->i_sem);
    + file->private_data = sysfs_new_dirent(parent_sd, NULL);
    + up(&dentry->d_inode->i_sem);
    +
    + return file->private_data ? 0 : -ENOMEM;
    +}
    +
    +static int sysfs_dir_close(struct inode *inode, struct file *file)
    +{
    + struct dentry *dentry = file->f_dentry;
    + struct sysfs_dirent *cursor = file->private_data;
    +
    + down(&dentry->d_inode->i_sem);
    + list_del_init(&cursor->s_sibling);
    + up(&dentry->d_inode->i_sem);
    +
    + release_sysfs_dirent(cursor);
    +
    + return 0;
    +}
    +
    +/* Relationship between s_mode and the DT_xxx types */
    +static inline unsigned char dt_type(struct sysfs_dirent *sd)
    +{
    + return (sd->s_mode >> 12) & 15;
    +}
    +
    +static int sysfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
    +{
    + struct dentry *dentry = filp->f_dentry;
    + struct sysfs_dirent *parent_sd = dentry->d_fsdata;
    + struct sysfs_dirent *cursor = filp->private_data;
    + struct list_head *p, *q = &cursor->s_sibling;
    + ino_t ino;
    + int i = filp->f_pos;
    +
    + switch (i) {
    + case 0:
    + ino = dentry->d_inode->i_ino;
    + if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
    + break;
    + filp->f_pos++;
    + i++;
    + /* fallthrough */
    + case 1:
    + ino = parent_ino(dentry);
    + if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
    + break;
    + filp->f_pos++;
    + i++;
    + /* fallthrough */
    + default:
    + if (filp->f_pos == 2) {
    + list_del(q);
    + list_add(q, &parent_sd->s_children);
    + }
    + for (p = q->next; p != &parent_sd->s_children; p = p->next) {
    + struct sysfs_dirent *next;
    + const char *name;
    + int len;
    +
    + next = list_entry(p, struct sysfs_dirent, s_sibling);
    + if (!next->s_element)
    + continue;
    +
    + name = sysfs_get_name(next);
    + len = strlen(name);
    + if (next->s_dentry)
    + ino = next->s_dentry->d_inode->i_ino;
    + else
    + ino = iunique(sysfs_sb, 2);
    +
    + if (filldir(dirent, name, len, filp->f_pos, ino,
    + dt_type(next)) < 0)
    + return 0;
    +
    + list_del(q);
    + list_add(q, p);
    + p = q;
    + filp->f_pos++;
    + }
    + }
    + return 0;
    +}
    +
    +static loff_t sysfs_dir_lseek(struct file *file, loff_t offset, int origin)
    +{
    + struct dentry *dentry = file->f_dentry;
    +
    + down(&dentry->d_inode->i_sem);
    + switch (origin) {
    + case 1:
    + offset += file->f_pos;
    + case 0:
    + if (offset >= 0)
    + break;
    + default:
    + up(&file->f_dentry->d_inode->i_sem);
    + return -EINVAL;
    + }
    + if (offset != file->f_pos) {
    + file->f_pos = offset;
    + if (file->f_pos >= 2) {
    + struct sysfs_dirent *sd = dentry->d_fsdata;
    + struct sysfs_dirent *cursor = file->private_data;
    + struct list_head *p;
    + loff_t n = file->f_pos - 2;
    +
    + list_del(&cursor->s_sibling);
    + p = sd->s_children.next;
    + while (n && p != &sd->s_children) {
    + struct sysfs_dirent *next;
    + next = list_entry(p, struct sysfs_dirent,
    + s_sibling);
    + if (next->s_element)
    + n--;
    + p = p->next;
    + }
    + list_add_tail(&cursor->s_sibling, p);
    + }
    + }
    + up(&dentry->d_inode->i_sem);
    + return offset;
    +}
    +
    +static struct file_operations sysfs_dir_operations = {
    + .open = sysfs_dir_open,
    + .release = sysfs_dir_close,
    + .llseek = sysfs_dir_lseek,
    + .read = generic_read_dir,
    + .readdir = sysfs_readdir,
    +};
    +
    +/* attaches attribute's sysfs_dirent to the dentry corresponding to the
    + * attribute file
    + */
    +static int sysfs_attach_attr(struct sysfs_dirent *sd, struct dentry *dentry)
    +{
    + struct attribute *attr = sd->s_element;
    + int error;
    +
    + error = sysfs_create(dentry, (attr->mode & S_IALLUGO) | S_IFREG, init_file);
    + if (error)
    + return error;
    +
    + dentry->d_op = &sysfs_dentry_ops;
    + dentry->d_fsdata = sysfs_get(sd);
    + sd->s_dentry = dentry;
    + d_rehash(dentry);
    +
    + return 0;
    +}
    +
    +static struct dentry *sysfs_lookup(struct inode *dir, struct dentry *dentry,
    + struct nameidata *nd)
    +{
    + struct sysfs_dirent *parent_sd = dentry->d_parent->d_fsdata;
    + struct sysfs_dirent *sd;
    + int found = 0;
    + int err = 0;
    +
    + list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
    + if (sd->s_type & CONFIGFS_NOT_PINNED) {
    + const unsigned char *name = sysfs_get_name(sd);
    +
    + if (strcmp(name, dentry->d_name.name))
    + continue;
    +
    + found = 1;
    + err = sysfs_attach_attr(sd, dentry);
    + break;
    + }
    + }
    +
    + if (!found) {
    + /*
    + * If it doesn't exist and it isn't a NOT_PINNED item,
    + * it must be negative.
    + */
    + return simple_lookup(dir, dentry, nd);
    + }
    +
    + return ERR_PTR(err);
    +}
    +
    +static struct inode_operations sysfs_dir_inode_operations;
    +
    +static int init_dir(struct inode *inode)
    +{
    + inode->i_op = &sysfs_dir_inode_operations;
    + inode->i_fop = &sysfs_dir_operations;
    +
    + /* directory inodes start off with i_nlink == 2 (for "." entry) */
    + inode->i_nlink++;
    + return 0;
    +}
    +
    +static int create_dir(struct kobject *k, struct dentry *p, struct dentry *d)
    +{
    + int error;
    + umode_t mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
    +
    + error = sysfs_create(d, mode, init_dir);
    + if (!error) {
    + error = sysfs_make_dirent(p->d_fsdata, d, k, mode, CONFIGFS_DIR);
    + if (!error) {
    + p->d_inode->i_nlink++;
    + (d)->d_op = &sysfs_dentry_ops;
    + }
    + }
    + return error;
    +}
    +
    +static struct vfsmount *sysfs_mount = NULL;
    +
    +static int configfs_create_dir(struct kobject *kobj, struct dentry *dentry)
    +{
    + struct dentry *parent;
    + int error = 0;
    +
    + BUG_ON(!kobj);
    +
    + if (kobj->parent)
    + parent = kobj->parent->dentry;
    + else if (sysfs_mount && sysfs_mount->mnt_sb)
    + parent = sysfs_mount->mnt_sb->s_root;
    + else
    + return -EFAULT;
    +
    + error = create_dir(kobj, parent, dentry);
    + if (!error)
    + kobj->dentry = dentry;
    + return error;
    +}
    +
    +static void remove_dir(struct dentry *d)
    +{
    + struct dentry *parent = dget(d->d_parent);
    + struct sysfs_dirent *sd;
    +
    + sd = d->d_fsdata;
    + list_del_init(&sd->s_sibling);
    + sysfs_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);
    +}
    +
    +/*
    + * sysfs_remove_dir - remove a kobject's directory.
    + * @kobj: kobject we're removing.
    + *
    + * The only thing special about this is that we remove any files in
    + * the directory before we remove the directory
    + */
    +static void configfs_remove_dir(struct kobject *kobj)
    +{
    + struct dentry *dentry = dget(kobj->dentry);
    +
    + if (!dentry)
    + return;
    +
    + remove_dir(dentry);
    + /* Drop reference from dget() on entrance. */
    + dput(dentry);
    +}
    +
    +#if 0
    +int sysfs_rename_dir(struct kobject *kobj, const char *new_name)
    +{
    + int error = 0;
    + struct dentry *new_dentry, *parent;
    +
    + if (!strcmp(kobject_name(kobj), new_name))
    + return -EINVAL;
    +
    + if (!kobj->parent)
    + return -EINVAL;
    +
    + down_write(&sysfs_rename_sem);
    + parent = kobj->parent->dentry;
    +
    + down(&parent->d_inode->i_sem);
    +
    + new_dentry = lookup_one_len(new_name, parent, strlen(new_name));
    + if (!IS_ERR(new_dentry)) {
    + if (!new_dentry->d_inode) {
    + error = kobject_set_name(kobj, "%s", new_name);
    + if (!error) {
    + d_add(new_dentry, NULL);
    + d_move(kobj->dentry, new_dentry);
    + } else
    + d_delete(new_dentry);
    + } else
    + error = -EEXIST;
    + dput(new_dentry);
    + }
    + up(&parent->d_inode->i_sem);
    + up_write(&sysfs_rename_sem);
    +
    + return error;
    +}
    +#endif
    +
    +/*
    + * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
    + * attributes and are removed by rmdir(). We recurse, taking i_sem
    + * on all children that are candidates for default detach. If the
    + * result is clean, then sysfs_detach_group() will handle dropping
    + * i_sem. If there is an error, the caller will clean up the i_sem
    + * holders via sysfs_detach_rollback().
    + */
    +static int sysfs_detach_prep(struct dentry *dentry)
    +{
    + struct sysfs_dirent *parent_sd = dentry->d_fsdata;
    + struct sysfs_dirent *sd;
    + int ret = 0;
    +
    + if (!list_empty(&parent_sd->s_links))
    + return -EBUSY;
    +
    + list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
    + if (sd->s_type & CONFIGFS_NOT_PINNED)
    + continue;
    + if (sd->s_type & CONFIGFS_USET_DEFAULT) {
    + down(&sd->s_dentry->d_inode->i_sem);
    + /* Mark that we've taken i_sem */
    + sd->s_type |= CONFIGFS_USET_DROPPING;
    +
    + ret = sysfs_detach_prep(sd->s_dentry);
    + if (!ret)
    + continue;
    + } else
    + ret = -ENOTEMPTY;
    + break;
    + }
    + return ret;
    +}
    +
    +/*
    + * Walk the tree, dropping i_sem wherever CONFIGFS_USET_DROPPING is
    + * set.
    + */
    +static void sysfs_detach_rollback(struct dentry *dentry)
    +{
    + struct sysfs_dirent *parent_sd = dentry->d_fsdata;
    + struct sysfs_dirent *sd;
    +
    + list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
    + if (sd->s_type & CONFIGFS_USET_DEFAULT) {
    + sysfs_detach_rollback(sd->s_dentry);
    +
    + if (sd->s_type & CONFIGFS_USET_DROPPING) {
    + sd->s_type &= ~CONFIGFS_USET_DROPPING;
    + up(&sd->s_dentry->d_inode->i_sem);
    + }
    + }
    + }
    +}
    +
    +static void detach_attrs(struct kobject *kobj)
    +{
    + struct dentry *dentry = dget(kobj->dentry);
    + struct sysfs_dirent *parent_sd;
    + struct sysfs_dirent *sd, *tmp;
    +
    + if (!dentry)
    + return;
    +
    + pr_debug("configfs %s: dropping attrs for dir\n", dentry->d_name.name);
    +
    + parent_sd = dentry->d_fsdata;
    + list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
    + if (!sd->s_element || !(sd->s_type & CONFIGFS_NOT_PINNED))
    + continue;
    + list_del_init(&sd->s_sibling);
    + sysfs_drop_dentry(sd, dentry);
    + sysfs_put(sd);
    + }
    +
    + /* Drop reference from dget() on entrance. */
    + dput(dentry);
    +}
    +
    +/*
    + * All of link_obj/unlink_obj/link_group/unlink_group require that
    + * subsys->su_sem is held.
    + */
    +
    +static void sysfs_detach_group(struct kobject *kobj);
    +
    +static void detach_groups(struct kset *group)
    +{
    + struct dentry *dentry = dget(group->kobj.dentry);
    + struct dentry *child;
    + struct sysfs_dirent *parent_sd;
    + struct sysfs_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;
    +
    + sysfs_detach_group(sd->s_element);
    + child->d_inode->i_flags |= S_DEAD;
    +
    + /*
    + * From rmdir/unregister, a sysfs_detach_prep() pass
    + * has taken our i_sem for us. Drop it.
    + * From mkdir/register cleanup, there is no sem held.
    + */
    + if (sd->s_type & CONFIGFS_USET_DROPPING)
    + up(&child->d_inode->i_sem);
    +
    + d_delete(child);
    + dput(child);
    + }
    +
    + /**
    + * Drop reference from dget() on entrance.
    + */
    + dput(dentry);
    +}
    +
    +static void sysfs_detach_item(struct kobject *kobj)
    +{
    + detach_attrs(kobj);
    + configfs_remove_dir(kobj);
    +}
    +
    +static void unlink_obj(struct kobject *kobj)
    +{
    + struct kset *group;
    +
    + group = kobj->kset;
    + if (group) {
    + list_del_init(&kobj->entry);
    +
    + kobj->kset = NULL;
    + kobj->parent = NULL;
    + kobject_put(kobj);
    +
    + config_group_put(group);
    + }
    +}
    +
    +static void unlink_group(struct kset *group)
    +{
    + int i;
    + struct kset *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->subsys = NULL;
    + unlink_obj(&group->kobj);
    +}
    +
    +static void sysfs_detach_group(struct kobject *kobj)
    +{
    + detach_groups(to_config_group(kobj));
    + sysfs_detach_item(kobj);
    +}
    +
    +/*
    + * 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 type.
    + */
    +static void client_drop_item(struct kobject *parent_kobj, struct kobject *kobj)
    +{
    + struct kobj_type *type;
    +
    + type = parent_kobj->ktype;
    + BUG_ON(!type);
    +
    + if (type->ct_group_ops && type->ct_group_ops->drop_item)
    + type->ct_group_ops->drop_item(to_config_group(parent_kobj), kobj);
    + else
    + kobject_put(kobj);
    +}
    +
    +static int sysfs_attach_group(struct kobject *parent_kobj, struct kobject *kobj, struct dentry *dentry);
    +
    +static int populate_attrs(struct kobject *kobj)
    +{
    + struct kobj_type *t = kobj->ktype;
    + struct attribute *attr;
    + int error = 0;
    + int i;
    +
    + if (!t)
    + return -EINVAL;
    + if (t->default_attrs) {
    + for (i = 0; (attr = t->default_attrs[i]) != NULL; i++) {
    + if ((error = configfs_create_file(kobj, attr)))
    + break;
    + }
    + }
    +
    + if (error)
    + detach_attrs(kobj);
    +
    + return error;
    +}
    +
    +/*
    + * The goal is that sysfs_attach_item() (and
    + * sysfs_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.
    + *
    + * sysfs_detach_group() and sysfs_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 sysfs_attach_item(struct kobject *parent_kobj, struct kobject *kobj, struct dentry *dentry)
    +{
    + int ret;
    +
    + ret = configfs_create_dir(kobj, dentry);
    + if (!ret) {
    + ret = populate_attrs(kobj);
    + if (ret) {
    + configfs_remove_dir(kobj);
    + d_delete(dentry);
    + }
    + }
    + return ret;
    +}
    +
    +/*
    + * 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 kset *parent_group, struct kset *group)
    +{
    + int ret;
    + struct qstr name;
    + struct sysfs_dirent *sd;
    + /* We trust the caller holds a reference to parent */
    + struct dentry *child, *parent = parent_group->kobj.dentry;
    +
    + if (!group->kobj.k_name)
    + group->kobj.k_name = group->kobj.name;
    + name.name = group->kobj.k_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 = sysfs_attach_group(&parent_group->kobj,
    + &group->kobj, 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 kset *group)
    +{
    + struct kset *new_group;
    + struct dentry *dentry = group->kobj.dentry;
    + int ret = 0;
    + int i;
    +
    + if (group && group->default_groups) {
    + /* FYI, we're faking mkdir here
    + * I'm not sure we need this semaphore, as we're called
    + * from our parent's mkdir. That holds our parent's
    + * i_sem, so afaik lookup cannot continue through our
    + * parent to find us, let alone mess with our tree.
    + * That said, taking our i_sem is closer to mkdir
    + * emulation, and shouldn't hurt. */
    + down(&dentry->d_inode->i_sem);
    +
    + for (i = 0; group->default_groups[i]; i++) {
    + new_group = group->default_groups[i];
    +
    + ret = create_default_group(group, new_group);
    + if (ret)
    + break;
    + }
    +
    + up(&dentry->d_inode->i_sem);
    + }
    +
    + if (ret)
    + detach_groups(group);
    + return ret;
    +}
    +
    +static int sysfs_attach_group(struct kobject *parent_kobj, struct kobject *kobj, struct dentry *dentry)
    +{
    + int ret;
    + struct sysfs_dirent *sd;
    +
    + ret = sysfs_attach_item(parent_kobj, kobj, dentry);
    + if (!ret) {
    + sd = dentry->d_fsdata;
    + sd->s_type |= CONFIGFS_USET_DIR;
    +
    + ret = populate_groups(to_config_group(kobj));
    + if (ret) {
    + sysfs_detach_item(kobj);
    + d_delete(dentry);
    + }
    + }
    + return ret;
    +}
    +
    +static void link_obj(struct kobject *parent_kobj, struct kobject *kobj)
    +{
    + /* Parent seems redundant with group, but it makes certain
    + * traversals much nicer. */
    + kobj->parent = parent_kobj;
    + kobj->kset = config_group_get(to_config_group(parent_kobj));
    + list_add_tail(&kobj->entry, &kobj->kset->cg_children);
    +
    + kobject_get(kobj);
    +}
    +
    +static void link_group(struct kset *parent_group, struct kset *group)
    +{
    + int i;
    + struct kset *new_group;
    + struct subsystem *subsys = NULL; /* gcc is a turd */
    +
    + link_obj(&parent_group->kobj, &group->kobj);
    +
    + if (parent_group->subsys)
    + subsys = parent_group->subsys;
    + else if (is_root(&parent_group->kobj))
    + subsys = to_configfs_subsystem(group);
    + else
    + BUG();
    + group->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);
    + }
    + }
    +}
    +
    +static int sysfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
    +{
    + int ret;
    + struct kset *group;
    + struct kobject *kobj;
    + struct kobject *parent_kobj;
    + struct subsystem *subsys;
    + struct sysfs_dirent *sd;
    + struct kobj_type *type;
    + struct module *owner;
    + char *name;
    +
    + if (dentry->d_parent == sysfs_sb->s_root)
    + return -EPERM;
    +
    + sd = dentry->d_parent->d_fsdata;
    + if (!(sd->s_type & CONFIGFS_USET_DIR))
    + return -EPERM;
    +
    + parent_kobj = sysfs_get_kobject(dentry->d_parent);
    + type = parent_kobj->ktype;
    + subsys = to_config_group(parent_kobj)->subsys;
    + BUG_ON(!subsys);
    +
    + if (!type || !type->ct_group_ops ||
    + (!type->ct_group_ops->make_group &&
    + !type->ct_group_ops->make_item)) {
    + kobject_put(parent_kobj);
    + return -EPERM; /* What lack-of-mkdir returns */
    + }
    +
    + name = kmalloc(dentry->d_name.len + 1, GFP_KERNEL);
    + if (!name) {
    + kobject_put(parent_kobj);
    + return -ENOMEM;
    + }
    + snprintf(name, dentry->d_name.len + 1, "%s", dentry->d_name.name);
    +
    + down_write(&subsys->rwsem);
    + group = NULL;
    + kobj = NULL;
    + if (type->ct_group_ops->make_group) {
    + group = type->ct_group_ops->make_group(to_config_group(parent_kobj), name);
    + if (group) {
    + link_group(to_config_group(parent_kobj), group);
    + kobj = &group->kobj;
    + }
    + } else {
    + kobj = type->ct_group_ops->make_item(to_config_group(parent_kobj), name);
    + if (kobj)
    + link_obj(parent_kobj, kobj);
    + }
    + up_write(&subsys->rwsem);
    +
    + kfree(name);
    + if (!kobj) {
    + kobject_put(parent_kobj);
    + return -ENOMEM;
    + }
    +
    + ret = -EINVAL;
    + type = kobj->ktype;
    + if (type) {
    + owner = type->ct_owner;
    + if (try_module_get(owner)) {
    + ret = group ?
    + sysfs_attach_group(parent_kobj, kobj, dentry) :
    + sysfs_attach_item(parent_kobj, kobj, dentry);
    +
    + if (ret) {
    + down_write(&subsys->rwsem);
    + if (group)
    + unlink_group(group);
    + else
    + unlink_obj(kobj);
    + client_drop_item(parent_kobj, kobj);
    + up_write(&subsys->rwsem);
    +
    + kobject_put(parent_kobj);
    + module_put(owner);
    + }
    + }
    + }
    +
    + return ret;
    +}
    +
    +static int sysfs_rmdir(struct inode *dir, struct dentry *dentry)
    +{
    + struct kobject *parent_kobj;
    + struct kobject *kobj;
    + struct subsystem *subsys;
    + struct sysfs_dirent *sd;
    + struct module *owner = NULL;
    + int ret;
    +
    + if (dentry->d_parent == sysfs_sb->s_root)
    + return -EPERM;
    +
    + sd = dentry->d_fsdata;
    + if (sd->s_type & CONFIGFS_USET_DEFAULT)
    + return -EPERM;
    +
    + parent_kobj = sysfs_get_kobject(dentry->d_parent);
    + subsys = to_config_group(parent_kobj)->subsys;
    + BUG_ON(!subsys);
    +
    + if (!parent_kobj->ktype) {
    + kobject_put(parent_kobj);
    + return -EINVAL;
    + }
    +
    + ret = sysfs_detach_prep(dentry);
    + if (ret) {
    + sysfs_detach_rollback(dentry);
    + kobject_put(parent_kobj);
    + return ret;
    + }
    +
    + kobj = sysfs_get_kobject(dentry);
    +
    + /* Drop reference from above, item already holds one. */
    + kobject_put(parent_kobj);
    +
    + if (kobj->ktype)
    + owner = kobj->ktype->ct_owner;
    +
    + if (sd->s_type & CONFIGFS_USET_DIR) {
    + sysfs_detach_group(kobj);
    +
    + down_write(&subsys->rwsem);
    + unlink_group(to_config_group(kobj));
    + } else {
    + sysfs_detach_item(kobj);
    +
    + down_write(&subsys->rwsem);
    + unlink_obj(kobj);
    + }
    +
    + client_drop_item(parent_kobj, kobj);
    + up_write(&subsys->rwsem);
    +
    + /* Drop our reference from above */
    + kobject_put(kobj);
    +
    + module_put(owner);
    +
    + return 0;
    +}
    +
    +int sysfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
    +{
    + int ret;
    + struct nameidata nd;
    + struct kobject *parent_kobj;
    + struct kobject *sl_target;
    + struct kobj_type *type;
    +
    + ret = -EPERM; /* What lack-of-symlink returns */
    + if (dentry->d_parent == sysfs_sb->s_root)
    + goto out;
    +
    + parent_kobj = sysfs_get_kobject(dentry->d_parent);
    + type = parent_kobj->ktype;
    +
    + if (!type || !type->sysfs_ops || !type->sysfs_ops->allow_link)
    + goto out_put;
    +
    + ret = get_target(symname, &nd, &sl_target);
    + if (ret)
    + goto out_put;
    +
    + ret = type->sysfs_ops->allow_link(parent_kobj, sl_target);
    + if (!ret)
    + ret = create_link(parent_kobj, sl_target, dentry);
    +
    + kobject_put(sl_target);
    + path_release(&nd);
    +
    + out_put:
    + kobject_put(parent_kobj);
    +
    + out:
    + return ret;
    +}
    +
    +static int sysfs_unlink(struct inode *dir, struct dentry *dentry)
    +{
    + struct sysfs_dirent *sd = dentry->d_fsdata;
    + struct sysfs_symlink *sl;
    + struct kobject *parent_kobj;
    + struct kobj_type *type;
    + int ret;
    +
    + ret = -EPERM; /* What lack-of-symlink returns */
    + if (!(sd->s_type & CONFIGFS_ITEM_LINK))
    + goto out;
    +
    + if (dentry->d_parent == sysfs_sb->s_root)
    + BUG();
    +
    + sl = sd->s_element;
    +
    + parent_kobj = sysfs_get_kobject(dentry->d_parent);
    + type = parent_kobj->ktype;
    +
    + list_del_init(&sd->s_sibling);
    + sysfs_drop_dentry(sd, dentry->d_parent);
    + dput(dentry);
    + sysfs_put(sd);
    +
    + /*
    + * drop_link() must be called before
    + * list_del_init(&sl->sl_list), so that the order of
    + * drop_link(this, target) and drop_item(target) is preserved.
    + */
    + if (type && type->sysfs_ops && type->sysfs_ops->drop_link)
    + type->sysfs_ops->drop_link(parent_kobj, sl->sl_target);
    +
    + /* FIXME: Needs lock */
    + list_del_init(&sl->sl_list);
    +
    + /* Put reference from create_link() */
    + kobject_put(sl->sl_target);
    + kfree(sl);
    +
    + kobject_put(parent_kobj);
    +
    + ret = 0;
    +
    + out:
    + return ret;
    +}
    +
    +static struct inode_operations sysfs_dir_inode_operations = {
    + .lookup = sysfs_lookup,
    + .mkdir = sysfs_mkdir,
    + .rmdir = sysfs_rmdir,
    + .symlink = sysfs_symlink,
    + .unlink = sysfs_unlink,
    +};
    +
    +static int sysfs_mnt_count = 0;
    +
    +int sysfs_pin_fs(void)
    +{
    + return simple_pin_fs("configfs", &sysfs_mount, &sysfs_mnt_count);
    +}
    +
    +void sysfs_release_fs(void)
    +{
    + simple_release_fs(&sysfs_mount, &sysfs_mnt_count);
    +}
    +
    +int configfs_register_subsystem(struct subsystem *subsys)
    +{
    + int err;
    + struct kset *group = &subsys->kset;
    + struct qstr name;
    + struct dentry *dentry;
    + struct sysfs_dirent *sd;
    +
    + err = sysfs_pin_fs();
    + if (err)
    + return err;
    +
    + if (!group->kobj.k_name)
    + group->kobj.k_name = group->kobj.name;
    +
    + sd = sysfs_sb->s_root->d_fsdata;
    + link_group(to_config_group(sd->s_element), group);
    +
    + down(&sysfs_sb->s_root->d_inode->i_sem);
    +
    + name.name = group->kobj.k_name;
    + name.len = strlen(name.name);
    + name.hash = full_name_hash(name.name, name.len);
    +
    + err = -ENOMEM;
    + dentry = d_alloc(sysfs_sb->s_root, &name);
    + if (!dentry)
    + goto out_release;
    +
    + d_add(dentry, NULL);
    +
    + err = sysfs_attach_group(sd->s_element, &group->kobj, dentry);
    + if (!err)
    + dentry = NULL;
    + else
    + d_delete(dentry);
    +
    + up(&sysfs_sb->s_root->d_inode->i_sem);
    +
    + if (dentry) {
    + dput(dentry);
    + out_release:
    + unlink_group(group);
    + sysfs_release_fs();
    + }
    +
    + return err;
    +}
    +
    +void configfs_unregister_subsystem(struct subsystem *subsys)
    +{
    + struct kset *group = &subsys->kset;
    + struct dentry *dentry = group->kobj.dentry;
    +
    + if (dentry->d_parent != sysfs_sb->s_root) {
    + printk(KERN_ERR
    + "configfs: Tried to unregister non-subsystem!\n");
    + return;
    + }
    +
    + down(&sysfs_sb->s_root->d_inode->i_sem);
    + down(&dentry->d_inode->i_sem);
    + if (sysfs_detach_prep(dentry)) {
    + printk(KERN_ERR
    + "configfs: Tried to unregister non-empty subsystem!\n");
    + }
    + sysfs_detach_group(&group->kobj);
    + dentry->d_inode->i_flags |= S_DEAD;
    + up(&dentry->d_inode->i_sem);
    +
    + d_delete(dentry);
    +
    + up(&sysfs_sb->s_root->d_inode->i_sem);
    +
    + dput(dentry);
    +
    + unlink_group(group);
    + sysfs_release_fs();
    +}
    +
    +/*
    + * mount.c - operations for initializing and mounting
    + */
    +
    +#define CONFIGFS_MAGIC 0x62656570
    +
    +static struct super_operations sysfs_ops = {
    + .statfs = simple_statfs,
    + .drop_inode = generic_delete_inode,
    +};
    +
    +static struct sysfs_dirent sysfs_root = {
    + .s_sibling = LIST_HEAD_INIT(sysfs_root.s_sibling),
    + .s_children = LIST_HEAD_INIT(sysfs_root.s_children),
    + .s_element = &sysfs_root_group.kobj,
    + .s_type = CONFIGFS_ROOT,
    +};
    +
    +static int sysfs_fill_super(struct super_block *sb, void *data, int silent)
    +{
    + struct inode *inode;
    + struct dentry *root;
    +
    + sb->s_blocksize = PAGE_CACHE_SIZE;
    + sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
    + sb->s_magic = CONFIGFS_MAGIC;
    + sb->s_op = &sysfs_ops;
    + sysfs_sb = sb;
    +
    + inode = sysfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO);
    + if (inode) {
    + inode->i_op = &sysfs_dir_inode_operations;
    + inode->i_fop = &sysfs_dir_operations;
    + /* directory inodes start off with i_nlink == 2 (for "." entry) */
    + inode->i_nlink++;
    + } else {
    + pr_debug("configfs: could not get root inode\n");
    + return -ENOMEM;
    + }
    +
    + root = d_alloc_root(inode);
    + if (!root) {
    + pr_debug("%s: could not get root dentry!\n", __FUNCTION__);
    + iput(inode);
    + return -ENOMEM;
    + }
    + config_group_init(&sysfs_root_group);
    + sysfs_root_group.kobj.dentry = root;
    + root->d_fsdata = &sysfs_root;
    + sb->s_root = root;
    + return 0;
    +}
    +
    +static struct super_block *sysfs_get_sb(struct file_system_type *fs_type,
    + int flags, const char *dev_name, void *data)
    +{
    + return get_sb_single(fs_type, flags, data, sysfs_fill_super);
    +}
    +
    +static struct file_system_type sysfs_fs_type = {
    + .name = "configfs",
    + .owner = THIS_MODULE,
    + .get_sb = sysfs_get_sb,
    + .kill_sb = kill_litter_super,
    +};
    +
    +static int __init sysfs_init(void)
    +{
    + int err = -ENOMEM;
    +
    + sysfs_dir_cachep = kmem_cache_create("configfs_dir_cache",
    + sizeof(struct sysfs_dirent), 0, 0, NULL, NULL);
    + if (!sysfs_dir_cachep)
    + goto out;
    +
    + err = register_filesystem(&sysfs_fs_type);
    + if (err)
    + goto out_err;
    + out:
    + return err;
    + out_err:
    + kmem_cache_destroy(sysfs_dir_cachep);
    + sysfs_dir_cachep = NULL;
    + goto out;
    +}
    +
    +static void __exit sysfs_exit(void)
    +{
    + unregister_filesystem(&sysfs_fs_type);
    +}
    +
    +MODULE_AUTHOR("Oracle");
    +MODULE_LICENSE("GPL");
    +MODULE_VERSION("0.0.1");
    +MODULE_DESCRIPTION
    + ("Simple RAM filesystem for user driven kernel subsystem configuration.");
    +
    +module_init(sysfs_init);
    +module_exit(sysfs_exit);
    +
    +/*
    + * configfs client helpers
    + */
    +
    +void config_group_init_type_name(struct kset *group, const char *name, struct kobj_type *type)
    +{
    + kobject_set_name(&group->kobj, name);
    + group->kobj.ktype = type;
    + config_group_init(group);
    +}
    +
    +void config_group_init(struct kset *group)
    +{
    + kobject_init(&group->kobj);
    + INIT_LIST_HEAD(&group->cg_children);
    +}
    +
    +void kobject_init_type_name(struct kobject *kobj, const char *name, struct kobj_type *type)
    +{
    + kobject_set_name(kobj, name);
    + kobj->ktype = type;
    + kobject_init(kobj);
    +}
    +
    +EXPORT_SYMBOL(configfs_register_subsystem);
    +EXPORT_SYMBOL(configfs_unregister_subsystem);
    +EXPORT_SYMBOL(config_group_init_type_name);
    +EXPORT_SYMBOL(config_group_init);
    +EXPORT_SYMBOL(kobject_init_type_name);
    -
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      Last update: 2005-08-31 01:02    [W:0.135 / U:59.236 seconds]
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