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Commit 4e4d6d86 authored by Eric W. Biederman's avatar Eric W. Biederman Committed by Greg Kroah-Hartman
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sysfs: Add s_hash to sysfs_dirent and order directory entries by hash 



Compute a 31 bit hash of directory entries (that can fit in a signed
32bit off_t) and index the sysfs directory entries by that hash,
replacing the per directory indexes by name and by inode.  Because we
now only use a single rbtree this reduces the size of sysfs_dirent by 2
pointers.  Because we have fewer cases to deal with the code is now
simpler.

For now I use the simple hash that the dcache uses as that is easy to
use and seems simple enough.

In addition to makeing the code simpler using a hash for the file
position in readdir brings sysfs in line with other filesystems that
have non-trivial directory structures.

Signed-off-by: default avatarEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent dcd6c922

fs/sysfs/dir.c

+116 −103
Original line number Diff line number Diff line
@@ -22,76 +22,103 @@ 
#include <linux/mutex.h>

#include <linux/slab.h>

#include <linux/security.h>

#include <linux/hash.h>

#include "sysfs.h"



DEFINE_MUTEX(sysfs_mutex);

DEFINE_SPINLOCK(sysfs_assoc_lock);



#define to_sysfs_dirent(X) rb_entry((X), struct sysfs_dirent, s_rb);



static DEFINE_SPINLOCK(sysfs_ino_lock);

static DEFINE_IDA(sysfs_ino_ida);



/**

 *	sysfs_link_sibling - link sysfs_dirent into sibling list

 *	sysfs_name_hash

 *	@ns:   Namespace tag to hash

 *	@name: Null terminated string to hash

 *

 *	Returns 31 bit hash of ns + name (so it fits in an off_t )

 */

static unsigned int sysfs_name_hash(const void *ns, const char *name)

{

	unsigned long hash = init_name_hash();

	unsigned int len = strlen(name);

	while (len--)

		hash = partial_name_hash(*name++, hash);

	hash = ( end_name_hash(hash) ^ hash_ptr( (void *)ns, 31 ) );

	hash &= 0x7fffffffU;

	/* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */

	if (hash < 1)

		hash += 2;

	if (hash >= INT_MAX)

		hash = INT_MAX - 1;

	return hash;

}



static int sysfs_name_compare(unsigned int hash, const void *ns,

	const char *name, const struct sysfs_dirent *sd)

{

	if (hash != sd->s_hash)

		return hash - sd->s_hash;

	if (ns != sd->s_ns)

		return ns - sd->s_ns;

	return strcmp(name, sd->s_name);

}



static int sysfs_sd_compare(const struct sysfs_dirent *left,

			    const struct sysfs_dirent *right)

{

	return sysfs_name_compare(left->s_hash, left->s_ns, left->s_name,

				  right);

}



/**

 *	sysfs_link_subling - link sysfs_dirent into sibling rbtree

 *	@sd: sysfs_dirent of interest

 *

 *	Link @sd into its sibling list which starts from

 *	Link @sd into its sibling rbtree which starts from

 *	sd->s_parent->s_dir.children.

 *

 *	Locking:

 *	mutex_lock(sysfs_mutex)

 *

 *	RETURNS:

 *	0 on susccess -EEXIST on failure.

 */

static void sysfs_link_sibling(struct sysfs_dirent *sd)

static int sysfs_link_sibling(struct sysfs_dirent *sd)

{

	struct sysfs_dirent *parent_sd = sd->s_parent;



	struct rb_node **p;

	struct rb_node *parent;

	struct rb_node **node = &sd->s_parent->s_dir.children.rb_node;

	struct rb_node *parent = NULL;



	if (sysfs_type(sd) == SYSFS_DIR)

		parent_sd->s_dir.subdirs++;



	p = &parent_sd->s_dir.inode_tree.rb_node;

	parent = NULL;

	while (*p) {

		parent = *p;

#define node	rb_entry(parent, struct sysfs_dirent, inode_node)

		if (sd->s_ino < node->s_ino) {

			p = &node->inode_node.rb_left;

		} else if (sd->s_ino > node->s_ino) {

			p = &node->inode_node.rb_right;

		} else {

			printk(KERN_CRIT "sysfs: inserting duplicate inode '%lx'\n",

			       (unsigned long) sd->s_ino);

			BUG();

		}

#undef node

	}

	rb_link_node(&sd->inode_node, parent, p);

	rb_insert_color(&sd->inode_node, &parent_sd->s_dir.inode_tree);



	p = &parent_sd->s_dir.name_tree.rb_node;

	parent = NULL;

	while (*p) {

		int c;

		parent = *p;

#define node	rb_entry(parent, struct sysfs_dirent, name_node)

		c = strcmp(sd->s_name, node->s_name);

		if (c < 0) {

			p = &node->name_node.rb_left;

		} else {

			p = &node->name_node.rb_right;

		}

#undef node

		sd->s_parent->s_dir.subdirs++;



	while (*node) {

		struct sysfs_dirent *pos;

		int result;



		pos = to_sysfs_dirent(*node);

		parent = *node;

		result = sysfs_sd_compare(sd, pos);

		if (result < 0)

			node = &pos->s_rb.rb_left;

		else if (result > 0)

			node = &pos->s_rb.rb_right;

		else

			return -EEXIST;

	}

	rb_link_node(&sd->name_node, parent, p);

	rb_insert_color(&sd->name_node, &parent_sd->s_dir.name_tree);

	/* add new node and rebalance the tree */

	rb_link_node(&sd->s_rb, parent, node);

	rb_insert_color(&sd->s_rb, &sd->s_parent->s_dir.children);

	return 0;

}



/**

 *	sysfs_unlink_sibling - unlink sysfs_dirent from sibling list

 *	sysfs_unlink_sibling - unlink sysfs_dirent from sibling rbtree

 *	@sd: sysfs_dirent of interest

 *

 *	Unlink @sd from its sibling list which starts from

 *	Unlink @sd from its sibling rbtree which starts from

 *	sd->s_parent->s_dir.children.

 *

 *	Locking:
@@ -102,8 +129,7 @@ static void sysfs_unlink_sibling(struct sysfs_dirent *sd) 
	if (sysfs_type(sd) == SYSFS_DIR)

		sd->s_parent->s_dir.subdirs--;



	rb_erase(&sd->inode_node, &sd->s_parent->s_dir.inode_tree);

	rb_erase(&sd->name_node, &sd->s_parent->s_dir.name_tree);

	rb_erase(&sd->s_rb, &sd->s_parent->s_dir.children);

}



/**
@@ -402,6 +428,7 @@ void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt, 
int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)

{

	struct sysfs_inode_attrs *ps_iattr;

	int ret;



	if (!!sysfs_ns_type(acxt->parent_sd) != !!sd->s_ns) {

		WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n",
@@ -410,12 +437,12 @@ int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd) 
		return -EINVAL;

	}



	if (sysfs_find_dirent(acxt->parent_sd, sd->s_ns, sd->s_name))

		return -EEXIST;



	sd->s_hash = sysfs_name_hash(sd->s_ns, sd->s_name);

	sd->s_parent = sysfs_get(acxt->parent_sd);



	sysfs_link_sibling(sd);

	ret = sysfs_link_sibling(sd);

	if (ret)

		return ret;



	/* Update timestamps on the parent */

	ps_iattr = acxt->parent_sd->s_iattr;
@@ -565,8 +592,8 @@ struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd, 
				       const void *ns,

				       const unsigned char *name)

{

	struct rb_node *p = parent_sd->s_dir.name_tree.rb_node;

	struct sysfs_dirent *found = NULL;

	struct rb_node *node = parent_sd->s_dir.children.rb_node;

	unsigned int hash;



	if (!!sysfs_ns_type(parent_sd) != !!ns) {

		WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n",
@@ -575,34 +602,22 @@ struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd, 
		return NULL;

	}



	while (p) {

		int c;

#define node	rb_entry(p, struct sysfs_dirent, name_node)

		c = strcmp(name, node->s_name);

		if (c < 0) {

			p = node->name_node.rb_left;

		} else if (c > 0) {

			p = node->name_node.rb_right;

		} else {

			found = node;

			p = node->name_node.rb_left;

		}

#undef node

	hash = sysfs_name_hash(ns, name);

	while (node) {

		struct sysfs_dirent *sd;

		int result;



		sd = to_sysfs_dirent(node);

		result = sysfs_name_compare(hash, ns, name, sd);

		if (result < 0)

			node = node->rb_left;

		else if (result > 0)

			node = node->rb_right;

		else

			return sd;

	}



	if (found) {

		while (found->s_ns != ns) {

			p = rb_next(&found->name_node);

			if (!p)

				return NULL;

			found = rb_entry(p, struct sysfs_dirent, name_node);

			if (strcmp(name, found->s_name))

	return NULL;

}

	}



	return found;

}



/**

 *	sysfs_get_dirent - find and get sysfs_dirent with the given name
@@ -804,9 +819,9 @@ static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd) 


	pr_debug("sysfs %s: removing dir\n", dir_sd->s_name);

	sysfs_addrm_start(&acxt, dir_sd);

	pos = rb_first(&dir_sd->s_dir.inode_tree);

	pos = rb_first(&dir_sd->s_dir.children);

	while (pos) {

		struct sysfs_dirent *sd = rb_entry(pos, struct sysfs_dirent, inode_node);

		struct sysfs_dirent *sd = to_sysfs_dirent(pos);

		pos = rb_next(pos);

		if (sysfs_type(sd) != SYSFS_DIR)

			sysfs_remove_one(&acxt, sd);
@@ -919,38 +934,36 @@ static int sysfs_dir_release(struct inode *inode, struct file *filp) 
}



static struct sysfs_dirent *sysfs_dir_pos(const void *ns,

	struct sysfs_dirent *parent_sd,	ino_t ino, struct sysfs_dirent *pos)

	struct sysfs_dirent *parent_sd,	loff_t hash, struct sysfs_dirent *pos)

{

	if (pos) {

		int valid = !(pos->s_flags & SYSFS_FLAG_REMOVED) &&

			pos->s_parent == parent_sd &&

			ino == pos->s_ino;

			hash == pos->s_hash;

		sysfs_put(pos);

		if (!valid)

			pos = NULL;

	}

	if (!pos && (ino > 1) && (ino < INT_MAX)) {

		struct rb_node *p = parent_sd->s_dir.inode_tree.rb_node;

		while (p) {

#define node	rb_entry(p, struct sysfs_dirent, inode_node)

			if (ino < node->s_ino) {

				pos = node;

				p = node->inode_node.rb_left;

			} else if (ino > node->s_ino) {

				p = node->inode_node.rb_right;

			} else {

				pos = node;

	if (!pos && (hash > 1) && (hash < INT_MAX)) {

		struct rb_node *node = parent_sd->s_dir.children.rb_node;

		while (node) {

			pos = to_sysfs_dirent(node);



			if (hash < pos->s_hash)

				node = node->rb_left;

			else if (hash > pos->s_hash)

				node = node->rb_right;

			else

				break;

		}

#undef node

		}

	}

	/* Skip over entries in the wrong namespace */

	while (pos && pos->s_ns != ns) {

		struct rb_node *p = rb_next(&pos->inode_node);

		if (!p)

		struct rb_node *node = rb_next(&pos->s_rb);

		if (!node)

			pos = NULL;

		else

			pos = rb_entry(p, struct sysfs_dirent, inode_node);

			pos = to_sysfs_dirent(node);

	}

	return pos;

}
@@ -960,11 +973,11 @@ static struct sysfs_dirent *sysfs_dir_next_pos(const void *ns, 
{

	pos = sysfs_dir_pos(ns, parent_sd, ino, pos);

	if (pos) do {

		struct rb_node *p = rb_next(&pos->inode_node);

		if (!p)

		struct rb_node *node = rb_next(&pos->s_rb);

		if (!node)

			pos = NULL;

		else

			pos = rb_entry(p, struct sysfs_dirent, inode_node);

			pos = to_sysfs_dirent(node);

	} while (pos && pos->s_ns != ns);

	return pos;

}
@@ -1006,7 +1019,7 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir) 
		len = strlen(name);

		ino = pos->s_ino;

		type = dt_type(pos);

		filp->f_pos = ino;

		filp->f_pos = pos->s_hash;

		filp->private_data = sysfs_get(pos);



		mutex_unlock(&sysfs_mutex);

fs/sysfs/sysfs.h

+4 −5
Original line number Diff line number Diff line
@@ -20,9 +20,8 @@ struct sysfs_elem_dir { 
	struct kobject		*kobj;



	unsigned long		subdirs;



	struct rb_root		inode_tree;

	struct rb_root		name_tree;

	/* children rbtree starts here and goes through sd->s_rb */

	struct rb_root		children;

};



struct sysfs_elem_symlink {
@@ -62,8 +61,7 @@ struct sysfs_dirent { 
	struct sysfs_dirent	*s_parent;

	const char		*s_name;



	struct rb_node		inode_node;

	struct rb_node		name_node;

	struct rb_node		s_rb;



	union {

		struct completion	*completion;
@@ -71,6 +69,7 @@ struct sysfs_dirent { 
	} u;



	const void		*s_ns; /* namespace tag */

	unsigned int		s_hash; /* ns + name hash */

	union {

		struct sysfs_elem_dir		s_dir;

		struct sysfs_elem_symlink	s_symlink;