fix ext3 block bitmap leakage

This patch fixes ext3 block bitmap leakage,
which leads to the following fsck messages on
_healthy_ filesystem:
Block bitmap differences:  -64159 -73707

All kernels up to 2.6.17 have this bug.

Found by
   Vasily Averin <vvs@sw.ru> and Andrey Savochkin <saw@sawoct.com>
Test case triggered the issue was created by
   Dmitry Monakhov <dmonakhov@sw.ru>
Signed-Off-By: Kirill Korotaev <dev@openvz.org>
Signed-off-by: Adrian Bunk <bunk@stusta.de>

fs/ext3/inode.c

@@ -516,6 +516,7 @@ static int ext3_alloc_branch(handle_t *handle, struct inode *inode,
 
 	branch[0].key = cpu_to_le32(parent);
 	if (parent) {
+		keys = 1;
 		for (n = 1; n < num; n++) {
 			struct buffer_head *bh;
 			/* Allocate the next block */