Commit 47320fbe authored by Al Viro's avatar Al Viro Committed by Christoph Hellwig
Browse files

configfs: new object reprsenting tree fragments 



Refcounted, hangs of configfs_dirent, created by operations that add
fragments to configfs tree (mkdir and configfs_register_{subsystem,group}).
Will be used in the next commit to provide exclusion between fragment
removal and ->show/->store calls.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent f19e4ed1

fs/configfs/configfs_internal.h

+13 −2
Original line number Diff line number Diff line
@@ -20,6 +20,15 @@ 
#include <linux/list.h>

#include <linux/spinlock.h>



struct configfs_fragment {

	atomic_t frag_count;

	struct rw_semaphore frag_sem;

	bool frag_dead;

};



void put_fragment(struct configfs_fragment *);

struct configfs_fragment *get_fragment(struct configfs_fragment *);



struct configfs_dirent {

	atomic_t		s_count;

	int			s_dependent_count;
@@ -34,6 +43,7 @@ struct configfs_dirent { 
#ifdef CONFIG_LOCKDEP

	int			s_depth;

#endif

	struct configfs_fragment *s_frag;

};



#define CONFIGFS_ROOT		0x0001
@@ -61,8 +71,8 @@ extern int configfs_create(struct dentry *, umode_t mode, void (*init)(struct in 
extern int configfs_create_file(struct config_item *, const struct configfs_attribute *);

extern int configfs_create_bin_file(struct config_item *,

				    const struct configfs_bin_attribute *);

extern int configfs_make_dirent(struct configfs_dirent *,

				struct dentry *, void *, umode_t, int);

extern int configfs_make_dirent(struct configfs_dirent *, struct dentry *,

				void *, umode_t, int, struct configfs_fragment *);

extern int configfs_dirent_is_ready(struct configfs_dirent *);



extern void configfs_hash_and_remove(struct dentry * dir, const char * name);
@@ -137,6 +147,7 @@ static inline void release_configfs_dirent(struct configfs_dirent * sd) 
{

	if (!(sd->s_type & CONFIGFS_ROOT)) {

		kfree(sd->s_iattr);

		put_fragment(sd->s_frag);

		kmem_cache_free(configfs_dir_cachep, sd);

	}

}

fs/configfs/dir.c

+82 −23
Original line number Diff line number Diff line
@@ -151,11 +151,38 @@ configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd) 


#endif /* CONFIG_LOCKDEP */



static struct configfs_fragment *new_fragment(void)

{

	struct configfs_fragment *p;



	p = kmalloc(sizeof(struct configfs_fragment), GFP_KERNEL);

	if (p) {

		atomic_set(&p->frag_count, 1);

		init_rwsem(&p->frag_sem);

		p->frag_dead = false;

	}

	return p;

}



void put_fragment(struct configfs_fragment *frag)

{

	if (frag && atomic_dec_and_test(&frag->frag_count))

		kfree(frag);

}



struct configfs_fragment *get_fragment(struct configfs_fragment *frag)

{

	if (likely(frag))

		atomic_inc(&frag->frag_count);

	return frag;

}



/*

 * Allocates a new configfs_dirent and links it to the parent configfs_dirent

 */

static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent *parent_sd,

						   void *element, int type)

						   void *element, int type,

						   struct configfs_fragment *frag)

{

	struct configfs_dirent * sd;
@@ -175,6 +202,7 @@ static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent *paren 
		kmem_cache_free(configfs_dir_cachep, sd);

		return ERR_PTR(-ENOENT);

	}

	sd->s_frag = get_fragment(frag);

	list_add(&sd->s_sibling, &parent_sd->s_children);

	spin_unlock(&configfs_dirent_lock);
@@ -209,11 +237,11 @@ static int configfs_dirent_exists(struct configfs_dirent *parent_sd, 


int configfs_make_dirent(struct configfs_dirent * parent_sd,

			 struct dentry * dentry, void * element,

			 umode_t mode, int type)

			 umode_t mode, int type, struct configfs_fragment *frag)

{

	struct configfs_dirent * sd;



	sd = configfs_new_dirent(parent_sd, element, type);

	sd = configfs_new_dirent(parent_sd, element, type, frag);

	if (IS_ERR(sd))

		return PTR_ERR(sd);
@@ -260,7 +288,8 @@ static void init_symlink(struct inode * inode) 
 *	until it is validated by configfs_dir_set_ready()

 */



static int configfs_create_dir(struct config_item *item, struct dentry *dentry)

static int configfs_create_dir(struct config_item *item, struct dentry *dentry,

				struct configfs_fragment *frag)

{

	int error;

	umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
@@ -273,7 +302,8 @@ static int configfs_create_dir(struct config_item *item, struct dentry *dentry) 
		return error;



	error = configfs_make_dirent(p->d_fsdata, dentry, item, mode,

				     CONFIGFS_DIR | CONFIGFS_USET_CREATING);

				     CONFIGFS_DIR | CONFIGFS_USET_CREATING,

				     frag);

	if (unlikely(error))

		return error;
@@ -338,9 +368,10 @@ int configfs_create_link(struct configfs_symlink *sl, 
{

	int err = 0;

	umode_t mode = S_IFLNK | S_IRWXUGO;

	struct configfs_dirent *p = parent->d_fsdata;



	err = configfs_make_dirent(parent->d_fsdata, dentry, sl, mode,

				   CONFIGFS_ITEM_LINK);

	err = configfs_make_dirent(p, dentry, sl, mode,

				   CONFIGFS_ITEM_LINK, p->s_frag);

	if (!err) {

		err = configfs_create(dentry, mode, init_symlink);

		if (err) {
@@ -599,7 +630,8 @@ static int populate_attrs(struct config_item *item) 


static int configfs_attach_group(struct config_item *parent_item,

				 struct config_item *item,

				 struct dentry *dentry);

				 struct dentry *dentry,

				 struct configfs_fragment *frag);

static void configfs_detach_group(struct config_item *item);



static void detach_groups(struct config_group *group)
@@ -647,7 +679,8 @@ static void detach_groups(struct config_group *group) 
 * try using vfs_mkdir.  Just a thought.

 */

static int create_default_group(struct config_group *parent_group,

				struct config_group *group)

				struct config_group *group,

				struct configfs_fragment *frag)

{

	int ret;

	struct configfs_dirent *sd;
@@ -663,7 +696,7 @@ static int create_default_group(struct config_group *parent_group, 
		d_add(child, NULL);



		ret = configfs_attach_group(&parent_group->cg_item,

					    &group->cg_item, child);

					    &group->cg_item, child, frag);

		if (!ret) {

			sd = child->d_fsdata;

			sd->s_type |= CONFIGFS_USET_DEFAULT;
@@ -677,13 +710,14 @@ static int create_default_group(struct config_group *parent_group, 
	return ret;

}



static int populate_groups(struct config_group *group)

static int populate_groups(struct config_group *group,

			   struct configfs_fragment *frag)

{

	struct config_group *new_group;

	int ret = 0;



	list_for_each_entry(new_group, &group->default_groups, group_entry) {

		ret = create_default_group(group, new_group);

		ret = create_default_group(group, new_group, frag);

		if (ret) {

			detach_groups(group);

			break;
@@ -797,11 +831,12 @@ static void link_group(struct config_group *parent_group, struct config_group *g 
 */

static int configfs_attach_item(struct config_item *parent_item,

				struct config_item *item,

				struct dentry *dentry)

				struct dentry *dentry,

				struct configfs_fragment *frag)

{

	int ret;



	ret = configfs_create_dir(item, dentry);

	ret = configfs_create_dir(item, dentry, frag);

	if (!ret) {

		ret = populate_attrs(item);

		if (ret) {
@@ -831,12 +866,13 @@ static void configfs_detach_item(struct config_item *item) 


static int configfs_attach_group(struct config_item *parent_item,

				 struct config_item *item,

				 struct dentry *dentry)

				 struct dentry *dentry,

				 struct configfs_fragment *frag)

{

	int ret;

	struct configfs_dirent *sd;



	ret = configfs_attach_item(parent_item, item, dentry);

	ret = configfs_attach_item(parent_item, item, dentry, frag);

	if (!ret) {

		sd = dentry->d_fsdata;

		sd->s_type |= CONFIGFS_USET_DIR;
@@ -852,7 +888,7 @@ static int configfs_attach_group(struct config_item *parent_item, 
		 */

		inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD);

		configfs_adjust_dir_dirent_depth_before_populate(sd);

		ret = populate_groups(to_config_group(item));

		ret = populate_groups(to_config_group(item), frag);

		if (ret) {

			configfs_detach_item(item);

			d_inode(dentry)->i_flags |= S_DEAD;
@@ -1247,6 +1283,7 @@ static int configfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode 
	struct configfs_dirent *sd;

	const struct config_item_type *type;

	struct module *subsys_owner = NULL, *new_item_owner = NULL;

	struct configfs_fragment *frag;

	char *name;



	sd = dentry->d_parent->d_fsdata;
@@ -1265,6 +1302,12 @@ static int configfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode 
		goto out;

	}



	frag = new_fragment();

	if (!frag) {

		ret = -ENOMEM;

		goto out;

	}



	/* Get a working ref for the duration of this function */

	parent_item = configfs_get_config_item(dentry->d_parent);

	type = parent_item->ci_type;
@@ -1367,9 +1410,9 @@ static int configfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode 
	spin_unlock(&configfs_dirent_lock);



	if (group)

		ret = configfs_attach_group(parent_item, item, dentry);

		ret = configfs_attach_group(parent_item, item, dentry, frag);

	else

		ret = configfs_attach_item(parent_item, item, dentry);

		ret = configfs_attach_item(parent_item, item, dentry, frag);



	spin_lock(&configfs_dirent_lock);

	sd->s_type &= ~CONFIGFS_USET_IN_MKDIR;
@@ -1406,6 +1449,7 @@ out_put: 
	 * reference.

	 */

	config_item_put(parent_item);

	put_fragment(frag);



out:

	return ret;
@@ -1574,7 +1618,7 @@ static int configfs_dir_open(struct inode *inode, struct file *file) 
	 */

	err = -ENOENT;

	if (configfs_dirent_is_ready(parent_sd)) {

		file->private_data = configfs_new_dirent(parent_sd, NULL, 0);

		file->private_data = configfs_new_dirent(parent_sd, NULL, 0, NULL);

		if (IS_ERR(file->private_data))

			err = PTR_ERR(file->private_data);

		else
@@ -1732,8 +1776,13 @@ int configfs_register_group(struct config_group *parent_group, 
{

	struct configfs_subsystem *subsys = parent_group->cg_subsys;

	struct dentry *parent;

	struct configfs_fragment *frag;

	int ret;



	frag = new_fragment();

	if (!frag)

		return -ENOMEM;



	mutex_lock(&subsys->su_mutex);

	link_group(parent_group, group);

	mutex_unlock(&subsys->su_mutex);
@@ -1741,7 +1790,7 @@ int configfs_register_group(struct config_group *parent_group, 
	parent = parent_group->cg_item.ci_dentry;



	inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);

	ret = create_default_group(parent_group, group);

	ret = create_default_group(parent_group, group, frag);

	if (ret)

		goto err_out;
@@ -1749,12 +1798,14 @@ int configfs_register_group(struct config_group *parent_group, 
	configfs_dir_set_ready(group->cg_item.ci_dentry->d_fsdata);

	spin_unlock(&configfs_dirent_lock);

	inode_unlock(d_inode(parent));

	put_fragment(frag);

	return 0;

err_out:

	inode_unlock(d_inode(parent));

	mutex_lock(&subsys->su_mutex);

	unlink_group(group);

	mutex_unlock(&subsys->su_mutex);

	put_fragment(frag);

	return ret;

}

EXPORT_SYMBOL(configfs_register_group);
@@ -1842,10 +1893,17 @@ int configfs_register_subsystem(struct configfs_subsystem *subsys) 
	struct dentry *dentry;

	struct dentry *root;

	struct configfs_dirent *sd;

	struct configfs_fragment *frag;



	frag = new_fragment();

	if (!frag)

		return -ENOMEM;



	root = configfs_pin_fs();

	if (IS_ERR(root))

	if (IS_ERR(root)) {

		put_fragment(frag);

		return PTR_ERR(root);

	}



	if (!group->cg_item.ci_name)

		group->cg_item.ci_name = group->cg_item.ci_namebuf;
@@ -1861,7 +1919,7 @@ int configfs_register_subsystem(struct configfs_subsystem *subsys) 
		d_add(dentry, NULL);



		err = configfs_attach_group(sd->s_element, &group->cg_item,

					    dentry);

					    dentry, frag);

		if (err) {

			BUG_ON(d_inode(dentry));

			d_drop(dentry);
@@ -1879,6 +1937,7 @@ int configfs_register_subsystem(struct configfs_subsystem *subsys) 
		unlink_group(group);

		configfs_release_fs();

	}

	put_fragment(frag);



	return err;

}

fs/configfs/file.c

+2 −2
Original line number Diff line number Diff line
@@ -488,7 +488,7 @@ int configfs_create_file(struct config_item * item, const struct configfs_attrib 


	inode_lock_nested(d_inode(dir), I_MUTEX_NORMAL);

	error = configfs_make_dirent(parent_sd, NULL, (void *) attr, mode,

				     CONFIGFS_ITEM_ATTR);

				     CONFIGFS_ITEM_ATTR, parent_sd->s_frag);

	inode_unlock(d_inode(dir));



	return error;
@@ -510,7 +510,7 @@ int configfs_create_bin_file(struct config_item *item, 


	inode_lock_nested(dir->d_inode, I_MUTEX_NORMAL);

	error = configfs_make_dirent(parent_sd, NULL, (void *) bin_attr, mode,

				     CONFIGFS_ITEM_BIN_ATTR);

				     CONFIGFS_ITEM_BIN_ATTR, parent_sd->s_frag);

	inode_unlock(dir->d_inode);



	return error;

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