LU-808 llite: deny truncate beyond user rlimit

LU-808 llite: deny truncate beyond user rlimit

Add a call to inode_newsize_ok() in ll_setattr_raw() to ensure
that the file is not truncated beyond the VFS/VM maximum limits
or the user maximum file size, as set by rlimit.

Replace the PAGE_CACHE_MAXBYTES constant with MAX_LFS_FILESIZE,
which is already defined by the VFS.

Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I6b4f03820dd59d6b1c3429e9bbfea62c50206cc9
Reviewed-on: http://review.whamcloud.com/1635
Reviewed-by: Jinshan Xiong <jinshan.xiong@whamcloud.com>
Tested-by: Hudson
Reviewed-by: Bobi Jam <bobijam@whamcloud.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>