Commit c1befb88 authored Apr 17, 2014 by Jianyu Zhan Committed by Greg Kroah-Hartman Apr 25, 2014

kernfs: fix a subdir count leak



Currently kernfs_link_sibling() increates parent->dir.subdirs before
adding the node into parent's chidren rb tree.

Because it is possible that kernfs_link_sibling() couldn't find
a suitable slot and bail out, this leads to a mismatch between
elevated subdir count with actual children node numbers.

This patches fix this problem, by moving the subdir accouting
after the actual addtion happening.

Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent a798c10f

fs/kernfs/dir.c

+6 −3

Original line number	Diff line number	Diff line
		@@ -232,9 +232,6 @@ static int kernfs_link_sibling(struct kernfs_node *kn)
		struct rb_node **node = &kn->parent->dir.children.rb_node;
		struct rb_node *parent = NULL;

		if (kernfs_type(kn) == KERNFS_DIR)
		kn->parent->dir.subdirs++;

		while (*node) {
		struct kernfs_node *pos;
		int result;
		@@ -249,9 +246,15 @@ static int kernfs_link_sibling(struct kernfs_node *kn)
		else
		return -EEXIST;
		}

		/* add new node and rebalance the tree */
		rb_link_node(&kn->rb, parent, node);
		rb_insert_color(&kn->rb, &kn->parent->dir.children);

		/* successfully added, account subdir number */
		if (kernfs_type(kn) == KERNFS_DIR)
		kn->parent->dir.subdirs++;

		return 0;
		}