Commit e9c03af2 authored by Al Viro's avatar Al Viro Committed by Christoph Hellwig
Browse files

configfs: calculate the symlink target only once 



Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent 2743c515

fs/configfs/configfs_internal.h

+4 −15
Original line number Diff line number Diff line
@@ -34,7 +34,7 @@ struct configfs_dirent { 
	int			s_dependent_count;

	struct list_head	s_sibling;

	struct list_head	s_children;

	struct list_head	s_links;

	int			s_links;

	void			* s_element;

	int			s_type;

	umode_t			s_mode;
@@ -84,7 +84,6 @@ extern int configfs_setattr(struct dentry *dentry, struct iattr *iattr); 
extern struct dentry *configfs_pin_fs(void);

extern void configfs_release_fs(void);



extern struct rw_semaphore configfs_rename_sem;

extern const struct file_operations configfs_dir_operations;

extern const struct file_operations configfs_file_operations;

extern const struct file_operations configfs_bin_file_operations;
@@ -97,14 +96,8 @@ extern int configfs_symlink(struct inode *dir, struct dentry *dentry, 
			    const char *symname);

extern int configfs_unlink(struct inode *dir, struct dentry *dentry);



struct configfs_symlink {

	struct list_head sl_list;

	struct config_item *sl_target;

};



extern int configfs_create_link(struct configfs_symlink *sl,

				struct dentry *parent,

				struct dentry *dentry);

int configfs_create_link(struct configfs_dirent *target, struct dentry *parent,

		struct dentry *dentry, char *body);



static inline struct config_item * to_item(struct dentry * dentry)

{
@@ -132,10 +125,6 @@ static inline struct config_item *configfs_get_config_item(struct dentry *dentry 
	spin_lock(&dentry->d_lock);

	if (!d_unhashed(dentry)) {

		struct configfs_dirent * sd = dentry->d_fsdata;

		if (sd->s_type & CONFIGFS_ITEM_LINK) {

			struct configfs_symlink * sl = sd->s_element;

			item = config_item_get(sl->sl_target);

		} else

		item = config_item_get(sd->s_element);

	}

	spin_unlock(&dentry->d_lock);

fs/configfs/dir.c

+6 −46
Original line number Diff line number Diff line
@@ -22,7 +22,6 @@ 
#include <linux/configfs.h>

#include "configfs_internal.h"



DECLARE_RWSEM(configfs_rename_sem);

/*

 * Protects mutations of configfs_dirent linkage together with proper i_mutex

 * Also protects mutations of symlinks linkage to target configfs_dirent
@@ -191,7 +190,6 @@ static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent *paren 
		return ERR_PTR(-ENOMEM);



	atomic_set(&sd->s_count, 1);

	INIT_LIST_HEAD(&sd->s_links);

	INIT_LIST_HEAD(&sd->s_children);

	sd->s_element = element;

	sd->s_type = type;
@@ -353,17 +351,16 @@ int configfs_dirent_is_ready(struct configfs_dirent *sd) 
	return ret;

}



int configfs_create_link(struct configfs_symlink *sl,

			 struct dentry *parent,

			 struct dentry *dentry)

int configfs_create_link(struct configfs_dirent *target, struct dentry *parent,

		struct dentry *dentry, char *body)

{

	int err = 0;

	umode_t mode = S_IFLNK | S_IRWXUGO;

	struct configfs_dirent *p = parent->d_fsdata;

	struct inode *inode;



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

				   CONFIGFS_ITEM_LINK, p->s_frag);

	err = configfs_make_dirent(p, dentry, target, mode, CONFIGFS_ITEM_LINK,

			p->s_frag);

	if (err)

		return err;
@@ -371,6 +368,7 @@ int configfs_create_link(struct configfs_symlink *sl, 
	if (IS_ERR(inode))

		goto out_remove;



	inode->i_link = body;

	inode->i_op = &configfs_symlink_inode_operations;

	d_instantiate(dentry, inode);

	dget(dentry);  /* pin link dentries in core */
@@ -517,7 +515,7 @@ static int configfs_detach_prep(struct dentry *dentry, struct dentry **wait) 
	parent_sd->s_type |= CONFIGFS_USET_DROPPING;



	ret = -EBUSY;

	if (!list_empty(&parent_sd->s_links))

	if (parent_sd->s_links)

		goto out;



	ret = 0;
@@ -1575,44 +1573,6 @@ const struct inode_operations configfs_root_inode_operations = { 
	.setattr	= configfs_setattr,

};



#if 0

int configfs_rename_dir(struct config_item * item, const char *new_name)

{

	int error = 0;

	struct dentry * new_dentry, * parent;



	if (!strcmp(config_item_name(item), new_name))

		return -EINVAL;



	if (!item->parent)

		return -EINVAL;



	down_write(&configfs_rename_sem);

	parent = item->parent->dentry;



	inode_lock(d_inode(parent));



	new_dentry = lookup_one_len(new_name, parent, strlen(new_name));

	if (!IS_ERR(new_dentry)) {

		if (d_really_is_negative(new_dentry)) {

			error = config_item_set_name(item, "%s", new_name);

			if (!error) {

				d_add(new_dentry, NULL);

				d_move(item->dentry, new_dentry);

			}

			else

				d_delete(new_dentry);

		} else

			error = -EEXIST;

		dput(new_dentry);

	}

	inode_unlock(d_inode(parent));

	up_write(&configfs_rename_sem);



	return error;

}

#endif



static int configfs_dir_open(struct inode *inode, struct file *file)

{

	struct dentry * dentry = file->f_path.dentry;

fs/configfs/mount.c

+9 −0
Original line number Diff line number Diff line
@@ -28,9 +28,18 @@ static struct vfsmount *configfs_mount = NULL; 
struct kmem_cache *configfs_dir_cachep;

static int configfs_mnt_count = 0;





static void configfs_free_inode(struct inode *inode)

{

	if (S_ISLNK(inode->i_mode))

		kfree(inode->i_link);

	free_inode_nonrcu(inode);

}



static const struct super_operations configfs_ops = {

	.statfs		= simple_statfs,

	.drop_inode	= generic_delete_inode,

	.free_inode	= configfs_free_inode,

};



static struct config_group configfs_root_group = {

fs/configfs/symlink.c

+54 −110
Original line number Diff line number Diff line
@@ -55,41 +55,63 @@ static void fill_item_path(struct config_item * item, char * buffer, int length) 
	}

}



static int configfs_get_target_path(struct config_item *item,

		struct config_item *target, char *path)

{

	int depth, size;

	char *s;



	depth = item_depth(item);

	size = item_path_length(target) + depth * 3 - 1;

	if (size > PATH_MAX)

		return -ENAMETOOLONG;



	pr_debug("%s: depth = %d, size = %d\n", __func__, depth, size);



	for (s = path; depth--; s += 3)

		strcpy(s,"../");



	fill_item_path(target, path, size);

	pr_debug("%s: path = '%s'\n", __func__, path);

	return 0;

}



static int create_link(struct config_item *parent_item,

		       struct config_item *item,

		       struct dentry *dentry)

{

	struct configfs_dirent *target_sd = item->ci_dentry->d_fsdata;

	struct configfs_symlink *sl;

	char *body;

	int ret;



	ret = -ENOENT;

	if (!configfs_dirent_is_ready(target_sd))

		goto out;

	ret = -ENOMEM;

	sl = kmalloc(sizeof(struct configfs_symlink), GFP_KERNEL);

	if (sl) {

		return -ENOENT;



	body = kzalloc(PAGE_SIZE, GFP_KERNEL);

	if (!body)

		return -ENOMEM;



	configfs_get(target_sd);

	spin_lock(&configfs_dirent_lock);

	if (target_sd->s_type & CONFIGFS_USET_DROPPING) {

		spin_unlock(&configfs_dirent_lock);

			kfree(sl);

		configfs_put(target_sd);

		kfree(body);

		return -ENOENT;

	}

		sl->sl_target = config_item_get(item);

		list_add(&sl->sl_list, &target_sd->s_links);

	target_sd->s_links++;

	spin_unlock(&configfs_dirent_lock);

		ret = configfs_create_link(sl, parent_item->ci_dentry,

					   dentry);

	ret = configfs_get_target_path(item, item, body);

	if (!ret)

		ret = configfs_create_link(target_sd, parent_item->ci_dentry,

					   dentry, body);

	if (ret) {

		spin_lock(&configfs_dirent_lock);

			list_del_init(&sl->sl_list);

		target_sd->s_links--;

		spin_unlock(&configfs_dirent_lock);

			config_item_put(item);

			kfree(sl);

		}

		configfs_put(target_sd);

		kfree(body);

	}



out:

	return ret;

}
@@ -131,9 +153,8 @@ int configfs_symlink(struct inode *dir, struct dentry *dentry, const char *symna 
	 * Fake invisibility if dir belongs to a group/default groups hierarchy

	 * being attached

	 */

	ret = -ENOENT;

	if (!configfs_dirent_is_ready(sd))

		goto out;

		return -ENOENT;



	parent_item = configfs_get_config_item(dentry->d_parent);

	type = parent_item->ci_type;
@@ -193,15 +214,12 @@ int configfs_symlink(struct inode *dir, struct dentry *dentry, const char *symna 


out_put:

	config_item_put(parent_item);



out:

	return ret;

}



int configfs_unlink(struct inode *dir, struct dentry *dentry)

{

	struct configfs_dirent *sd = dentry->d_fsdata;

	struct configfs_symlink *sl;

	struct configfs_dirent *sd = dentry->d_fsdata, *target_sd;

	struct config_item *parent_item;

	const struct config_item_type *type;

	int ret;
@@ -210,7 +228,7 @@ int configfs_unlink(struct inode *dir, struct dentry *dentry) 
	if (!(sd->s_type & CONFIGFS_ITEM_LINK))

		goto out;



	sl = sd->s_element;

	target_sd = sd->s_element;



	parent_item = configfs_get_config_item(dentry->d_parent);

	type = parent_item->ci_type;
@@ -224,21 +242,18 @@ int configfs_unlink(struct inode *dir, struct dentry *dentry) 


	/*

	 * drop_link() must be called before

	 * list_del_init(&sl->sl_list), so that the order of

	 * decrementing target's ->s_links, so that the order of

	 * drop_link(this, target) and drop_item(target) is preserved.

	 */

	if (type && type->ct_item_ops &&

	    type->ct_item_ops->drop_link)

		type->ct_item_ops->drop_link(parent_item,

					       sl->sl_target);

					       target_sd->s_element);



	spin_lock(&configfs_dirent_lock);

	list_del_init(&sl->sl_list);

	target_sd->s_links--;

	spin_unlock(&configfs_dirent_lock);



	/* Put reference from create_link() */

	config_item_put(sl->sl_target);

	kfree(sl);

	configfs_put(target_sd);



	config_item_put(parent_item);
@@ -248,79 +263,8 @@ out: 
	return ret;

}



static int configfs_get_target_path(struct config_item * item, struct config_item * target,

				   char *path)

{

	char * s;

	int depth, size;



	depth = item_depth(item);

	size = item_path_length(target) + depth * 3 - 1;

	if (size > PATH_MAX)

		return -ENAMETOOLONG;



	pr_debug("%s: depth = %d, size = %d\n", __func__, depth, size);



	for (s = path; depth--; s += 3)

		strcpy(s,"../");



	fill_item_path(target, path, size);

	pr_debug("%s: path = '%s'\n", __func__, path);



	return 0;

}



static int configfs_getlink(struct dentry *dentry, char * path)

{

	struct config_item *item, *target_item;

	int error = 0;



	item = configfs_get_config_item(dentry->d_parent);

	if (!item)

		return -EINVAL;



	target_item = configfs_get_config_item(dentry);

	if (!target_item) {

		config_item_put(item);

		return -EINVAL;

	}



	down_read(&configfs_rename_sem);

	error = configfs_get_target_path(item, target_item, path);

	up_read(&configfs_rename_sem);



	config_item_put(item);

	config_item_put(target_item);

	return error;



}



static const char *configfs_get_link(struct dentry *dentry,

				     struct inode *inode,

				     struct delayed_call *done)

{

	char *body;

	int error;



	if (!dentry)

		return ERR_PTR(-ECHILD);



	body = kzalloc(PAGE_SIZE, GFP_KERNEL);

	if (!body)

		return ERR_PTR(-ENOMEM);



	error = configfs_getlink(dentry, body);

	if (!error) {

		set_delayed_call(done, kfree_link, body);

		return body;

	}



	kfree(body);

	return ERR_PTR(error);

}



const struct inode_operations configfs_symlink_inode_operations = {

	.get_link = configfs_get_link,

	.get_link = simple_get_link,

	.setattr = configfs_setattr,

};