[JFFS2] Optimise jffs2_add_tn_to_list

Use an rbtree instead of a simple linked list. We were wasting 
an amazing amount of time in jffs2_add_tn_to_list(). 
Thanks to Artem Bityuckiy and Jarkko Jlavinen  for noticing.

Signed-off-by: David Woodhouse <dwmw2@infradead.org> 
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

fs/jffs2/nodelist.c

@@ -7,7 +7,7 @@
  *
  * For licensing information, see the file 'LICENCE' in this directory.
  *
- * $Id: nodelist.c,v 1.94 2005/04/13 13:22:35 dwmw2 Exp $
+ * $Id: nodelist.c,v 1.95 2005/07/05 21:03:07 dwmw2 Exp $
  *
  */
 
@@ -58,27 +58,61 @@ void jffs2_add_fd_to_list(struct jffs2_sb_info *c, struct jffs2_full_dirent *new
 /* Put a new tmp_dnode_info into the list, keeping the list in 
    order of increasing version
 */
-static void jffs2_add_tn_to_list(struct jffs2_tmp_dnode_info *tn, struct jffs2_tmp_dnode_info **list)
+
+static void jffs2_add_tn_to_list(struct jffs2_tmp_dnode_info *tn, struct rb_root *list)
 {
-	struct jffs2_tmp_dnode_info **prev = list;
-	
-	while ((*prev) && (*prev)->version < tn->version) {
-		prev = &((*prev)->next);
-	}
-	tn->next = (*prev);
-        *prev = tn;
+	struct rb_node **p = &list->rb_node;
+	struct rb_node * parent = NULL;
+	struct jffs2_tmp_dnode_info *this;
+
+	while (*p) {
+		parent = *p;
+		this = rb_entry(parent, struct jffs2_tmp_dnode_info, rb);
+
+		if (tn->version < this->version)
+			p = &(*p)->rb_left;
+		else if (tn->version > this->version)
+			p = &(*p)->rb_right;
+		else if (tn < this)
+			p = &(*p)->rb_left;
+		else
+			p = &(*p)->rb_right;
+        }
+
+	rb_link_node(&tn->rb, parent, p);
+	rb_insert_color(&tn->rb, list);
 }
 
-static void jffs2_free_tmp_dnode_info_list(struct jffs2_tmp_dnode_info *tn)
+static void jffs2_free_tmp_dnode_info_list(struct rb_root *list)
 {
-	struct jffs2_tmp_dnode_info *next;
+	struct rb_node *this;
+	struct jffs2_tmp_dnode_info *tn;
+
+	this = list->rb_node;
 
-	while (tn) {
-		next = tn;
-		tn = tn->next;
-		jffs2_free_full_dnode(next->fn);
-		jffs2_free_tmp_dnode_info(next);
+	/* Now at bottom of tree */
+	while (this) {
+		if (this->rb_left)
+			this = this->rb_left;
+		else if (this->rb_right)
+			this = this->rb_right;
+		else {
+			tn = rb_entry(this, struct jffs2_tmp_dnode_info, rb);
+			jffs2_free_full_dnode(tn->fn);
+			jffs2_free_tmp_dnode_info(tn);
+
+			this = this->rb_parent;
+			if (!this)
+				break;
+
+			if (this->rb_left == &tn->rb)
+				this->rb_left = NULL;
+			else if (this->rb_right == &tn->rb)
+				this->rb_right = NULL;
+			else BUG();
+		}
 	}
+	list->rb_node = NULL;
 }
 
 static void jffs2_free_full_dirent_list(struct jffs2_full_dirent *fd)
@@ -108,12 +142,13 @@ static struct jffs2_raw_node_ref *jffs2_first_valid_node(struct jffs2_raw_node_r
    with this ino, returning the former in order of version */
 
 int jffs2_get_inode_nodes(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
-			  struct jffs2_tmp_dnode_info **tnp, struct jffs2_full_dirent **fdp,
+			  struct rb_root *tnp, struct jffs2_full_dirent **fdp,
 			  uint32_t *highest_version, uint32_t *latest_mctime,
 			  uint32_t *mctime_ver)
 {
 	struct jffs2_raw_node_ref *ref, *valid_ref;
-	struct jffs2_tmp_dnode_info *tn, *ret_tn = NULL;
+	struct jffs2_tmp_dnode_info *tn;
+	struct rb_root ret_tn = RB_ROOT;
 	struct jffs2_full_dirent *fd, *ret_fd = NULL;
 	union jffs2_node_union node;
 	size_t retlen;
@@ -450,7 +485,7 @@ int jffs2_get_inode_nodes(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
 	return 0;
 
  free_out:
-	jffs2_free_tmp_dnode_info_list(ret_tn);
+	jffs2_free_tmp_dnode_info_list(&ret_tn);
 	jffs2_free_full_dirent_list(ret_fd);
 	return err;
 }

fs/jffs2/nodelist.h

@@ -7,7 +7,7 @@
  *
  * For licensing information, see the file 'LICENCE' in this directory.
  *
- * $Id: nodelist.h,v 1.130 2005/04/09 10:46:59 dedekind Exp $
+ * $Id: nodelist.h,v 1.131 2005/07/05 21:03:07 dwmw2 Exp $
  *
  */
 
@@ -161,7 +161,7 @@ struct jffs2_full_dnode
 */
 struct jffs2_tmp_dnode_info
 {
-	struct jffs2_tmp_dnode_info *next;
+	struct rb_node rb;
 	struct jffs2_full_dnode *fn;
 	uint32_t version;
 };       
@@ -387,7 +387,7 @@ static inline struct jffs2_node_frag *frag_last(struct rb_root *root)
 D2(void jffs2_print_frag_list(struct jffs2_inode_info *f));
 void jffs2_add_fd_to_list(struct jffs2_sb_info *c, struct jffs2_full_dirent *new, struct jffs2_full_dirent **list);
 int jffs2_get_inode_nodes(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
-			  struct jffs2_tmp_dnode_info **tnp, struct jffs2_full_dirent **fdp,
+			  struct rb_root *tnp, struct jffs2_full_dirent **fdp,
 			  uint32_t *highest_version, uint32_t *latest_mctime,
 			  uint32_t *mctime_ver);
 void jffs2_set_inocache_state(struct jffs2_sb_info *c, struct jffs2_inode_cache *ic, int state);

fs/jffs2/readinode.c

@@ -7,7 +7,7 @@
  *
  * For licensing information, see the file 'LICENCE' in this directory.
  *
- * $Id: readinode.c,v 1.119 2005/03/01 10:34:03 dedekind Exp $
+ * $Id: readinode.c,v 1.120 2005/07/05 21:03:07 dwmw2 Exp $
  *
  */
 
@@ -500,7 +500,9 @@ static int jffs2_do_read_inode_internal(struct jffs2_sb_info *c,
 					struct jffs2_inode_info *f,
 					struct jffs2_raw_inode *latest_node)
 {
-	struct jffs2_tmp_dnode_info *tn_list, *tn;
+	struct jffs2_tmp_dnode_info *tn = NULL;
+	struct rb_root tn_list;
+	struct rb_node *rb, *repl_rb;
 	struct jffs2_full_dirent *fd_list;
 	struct jffs2_full_dnode *fn = NULL;
 	uint32_t crc;
@@ -522,9 +524,10 @@ static int jffs2_do_read_inode_internal(struct jffs2_sb_info *c,
 	}
 	f->dents = fd_list;
 
-	while (tn_list) {
-		tn = tn_list;
+	rb = rb_first(&tn_list);
 
+	while (rb) {
+		tn = rb_entry(rb, struct jffs2_tmp_dnode_info, rb);
 		fn = tn->fn;
 
 		if (f->metadata) {
@@ -556,7 +559,30 @@ static int jffs2_do_read_inode_internal(struct jffs2_sb_info *c,
 			mdata_ver = tn->version;
 		}
 	next_tn:
-		tn_list = tn->next;
+		BUG_ON(rb->rb_left);
+		repl_rb = NULL;
+		if (rb->rb_parent && rb->rb_parent->rb_left == rb) {
+			/* We were then left-hand child of our parent. We need
+			   to move our own right-hand child into our place. */
+			repl_rb = rb->rb_right;
+			if (repl_rb)
+				repl_rb->rb_parent = rb->rb_parent;
+		} else
+			repl_rb = NULL;
+
+		rb = rb_next(rb);
+
+		/* Remove the spent tn from the tree; don't bother rebalancing
+		   but put our right-hand child in our own place. */
+		if (tn->rb.rb_parent) {
+			if (tn->rb.rb_parent->rb_left == &tn->rb)
+				tn->rb.rb_parent->rb_left = repl_rb;
+			else if (tn->rb.rb_parent->rb_right == &tn->rb)
+				tn->rb.rb_parent->rb_right = repl_rb;
+			else BUG();
+		} else if (tn->rb.rb_right)
+			tn->rb.rb_right->rb_parent = NULL;
+
 		jffs2_free_tmp_dnode_info(tn);
 	}
 	D1(jffs2_sanitycheck_fragtree(f));