fix debugfs inode leak

Looking at the reiser4 crash, I found a leak in debugfs. In
debugfs_mknod(), we create the inode before checking if the dentry
already has one attached. We don't free it if that is the case.
Signed-off-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Adrian Bunk <bunk@stusta.de>

fs/debugfs/inode.c

@@ -67,12 +67,13 @@ static struct inode *debugfs_get_inode(struct super_block *sb, int mode, dev_t d
 static int debugfs_mknod(struct inode *dir, struct dentry *dentry,
 			 int mode, dev_t dev)
 {
-	struct inode *inode = debugfs_get_inode(dir->i_sb, mode, dev);
+	struct inode *inode;
 	int error = -EPERM;
 
 	if (dentry->d_inode)
 		return -EEXIST;
 
+	inode = debugfs_get_inode(dir->i_sb, mode, dev);
 	if (inode) {
 		d_instantiate(dentry, inode);
 		dget(dentry);