[PATCH] fuse: add bmap support

Add support for the BMAP operation for block device based filesystems.  This
is needed to support swap-files and lilo.

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>