EX-7601 llite: Compute compression chunk ranges

EX-7601 llite: Compute compression chunk ranges

Determine the edges of any leading and trailing compression
chunks touched by this IO and store them in the cl_io
struct.

The functionality in this patch also allows us to adjust
the lock and read rounding to do them more intelligently,
this will be done in a future patch.

Signed-off-by: Patrick Farrell <pfarrell@whamcloud.com>
Change-Id: I526563ea347fb0246f97f3532b823c4345c3fa27
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/51324
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>