[RFC][PATCH 3 of 4] Configfs is really sysfs
From: Daniel Phillips
Date: Tue Aug 30 2005 - 18:00:31 EST
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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