use btrfsck to check btrfs filesystems

[Christoph Hellwig]

On Wed, Dec 14, 2011 at 03:35:20PM +0800, Miao Xie wrote:
> We failed to get fsck program to check the btrfs file system, it is
> because btrfs uses its independent check tool which is named btrfsck
> to check the file system, so the common checker -- fsck -- could not
> find it, and reported there is no checker.
> 
> This patch fix it by using btrfsck directly. 
> 
> Signed-off-by: Miao Xie <miaox at cn.fujitsu.com>

Thanks, applied.