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Commit a406f758 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Greg Kroah-Hartman
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sysfs: use rb-tree for inode number lookup 



sysfs: use rb-tree for inode number lookup

This patch makes sysfs use red-black tree for inode number lookup.
Together with a previous patch to use red-black tree for name lookup,
this patch makes all sysfs lookups to have O(log n) complexity.

Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 58f2a4c7

fs/sysfs/dir.c

+50 −39
Original line number Diff line number Diff line
@@ -43,26 +43,30 @@ static DEFINE_IDA(sysfs_ino_ida); 
static void sysfs_link_sibling(struct sysfs_dirent *sd)

{

	struct sysfs_dirent *parent_sd = sd->s_parent;

	struct sysfs_dirent **pos;



	struct rb_node **p;

	struct rb_node *parent;



	BUG_ON(sd->s_sibling);



	if (sysfs_type(sd) == SYSFS_DIR)

		parent_sd->s_dir.subdirs++;



	/* Store directory entries in order by ino.  This allows

	 * readdir to properly restart without having to add a

	 * cursor into the s_dir.children list.

	 */

	for (pos = &parent_sd->s_dir.children; *pos; pos = &(*pos)->s_sibling) {

		if (sd->s_ino < (*pos)->s_ino)

			break;

	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", sd->s_ino);

			BUG();

		}

	sd->s_sibling = *pos;

	*pos = sd;

#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;
@@ -94,20 +98,10 @@ static void sysfs_link_sibling(struct sysfs_dirent *sd) 
 */

static void sysfs_unlink_sibling(struct sysfs_dirent *sd)

{

	struct sysfs_dirent **pos;



	if (sysfs_type(sd) == SYSFS_DIR)

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



	for (pos = &sd->s_parent->s_dir.children; *pos;

	     pos = &(*pos)->s_sibling) {

		if (*pos == sd) {

			*pos = sd->s_sibling;

			sd->s_sibling = NULL;

			break;

		}

	}



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

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

}
@@ -788,21 +782,19 @@ void sysfs_remove_subdir(struct sysfs_dirent *sd) 
static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd)

{

	struct sysfs_addrm_cxt acxt;

	struct sysfs_dirent **pos;

	struct rb_node *pos;



	if (!dir_sd)

		return;



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

	sysfs_addrm_start(&acxt, dir_sd);

	pos = &dir_sd->s_dir.children;

	while (*pos) {

		struct sysfs_dirent *sd = *pos;



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

	while (pos) {

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

		pos = rb_next(pos);

		if (sysfs_type(sd) != SYSFS_DIR)

			sysfs_remove_one(&acxt, sd);

		else

			pos = &(*pos)->s_sibling;

	}

	sysfs_addrm_finish(&acxt);
@@ -925,12 +917,28 @@ static struct sysfs_dirent *sysfs_dir_pos(const void *ns, 
			pos = NULL;

	}

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

		pos = parent_sd->s_dir.children;

		while (pos && (ino > pos->s_ino))

			pos = pos->s_sibling;

		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;

				break;

			}

#undef node

		}

	}

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

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

		if (!p)

			pos = NULL;

		else

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

	}

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

		pos = pos->s_sibling;

	return pos;

}
@@ -938,10 +946,13 @@ static struct sysfs_dirent *sysfs_dir_next_pos(const void *ns, 
	struct sysfs_dirent *parent_sd,	ino_t ino, struct sysfs_dirent *pos)

{

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

	if (pos)

		pos = pos->s_sibling;

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

		pos = pos->s_sibling;

	if (pos) do {

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

		if (!p)

			pos = NULL;

		else

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

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

	return pos;

}

fs/sysfs/sysfs.h

+2 −3
Original line number Diff line number Diff line
@@ -18,11 +18,10 @@ struct sysfs_open_dirent; 
/* type-specific structures for sysfs_dirent->s_* union members */

struct sysfs_elem_dir {

	struct kobject		*kobj;

	/* children list starts here and goes through sd->s_sibling */

	struct sysfs_dirent	*children;



	unsigned long		subdirs;



	struct rb_root		inode_tree;

	struct rb_root		name_tree;

};
@@ -61,9 +60,9 @@ struct sysfs_dirent { 
	struct lockdep_map	dep_map;

#endif

	struct sysfs_dirent	*s_parent;

	struct sysfs_dirent	*s_sibling;

	const char		*s_name;



	struct rb_node		inode_node;

	struct rb_node		name_node;



	union {