sysfs: use rb-tree for name lookups

sysfs: use rb-tree for name lookups

Use red-black tree for name lookups.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 7d240e6..3e937da 100644 (file)
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -45,6 +45,9 @@ 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)
@@ -60,6 +63,23 @@ static void sysfs_link_sibling(struct sysfs_dirent *sd)
        }
        sd->s_sibling = *pos;
        *pos = sd;
+
+       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
+       }
+       rb_link_node(&sd->name_node, parent, p);
+       rb_insert_color(&sd->name_node, &parent_sd->s_dir.name_tree);
 }
 
 /**
@@ -87,6 +107,8 @@ static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
                        break;
                }
        }
+
+       rb_erase(&sd->name_node, &sd->s_parent->s_dir.name_tree);
 }
 
 /**
@@ -546,15 +568,36 @@ struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
                                       const void *ns,
                                       const unsigned char *name)
 {
-       struct sysfs_dirent *sd;
+       struct rb_node *p = parent_sd->s_dir.name_tree.rb_node;
+       struct sysfs_dirent *found = 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
+       }
 
-       for (sd = parent_sd->s_dir.children; sd; sd = sd->s_sibling) {
-               if (ns && sd->s_ns && (sd->s_ns != ns))
-                       continue;
-               if (!strcmp(sd->s_name, name))
-                       return sd;
+       if (found && ns) {
+               while (found->s_ns && 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 NULL;
+
+       return found;
 }
 
 /**

diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 6348e2c..fe1a9e8 100644 (file)
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -11,6 +11,7 @@
 #include <linux/lockdep.h>
 #include <linux/kobject_ns.h>
 #include <linux/fs.h>
+#include <linux/rbtree.h>
 
 struct sysfs_open_dirent;
 
@@ -21,6 +22,8 @@ struct sysfs_elem_dir {
        struct sysfs_dirent     *children;
 
        unsigned long           subdirs;
+
+       struct rb_root          name_tree;
 };
 
 struct sysfs_elem_symlink {
@@ -61,6 +64,8 @@ struct sysfs_dirent {
        struct sysfs_dirent     *s_sibling;
        const char              *s_name;
 
+       struct rb_node          name_node;
+
        const void              *s_ns; /* namespace tag */
        union {
                struct sysfs_elem_dir           s_dir;