The patch integrates LSOM functionality with lfs find so that it
is possible to use LSOM functionality directly on the client. The
MDS fills in the mbo_size and mbo_blocks fields from the LSOM
xattr, if the actual size/blocks are not available, and then set
new OBD_MD_FLLSIZE and OBD_MD_FLLBLOCKS flags in the reply so that
the client knows these fields are valid.

The lfs find command adds "-l|--lazy" option to allow the use of
LSOM data from the MDS.

Add a new version of ioctl(LL_IOC_MDC_GETINFO) call that also returns
valid flags from the MDS RPC to userspace in struct lov_user_mds_data
so that it is possible to determine whether the size and blocks are
returned by the call.  The old LL_IOC_MDC_GETINFO ioctl number is
renamed to LL_IOC_MDC_GETINFO_OLD and is binary compatible, but
newly-compiled applications will use the new struct lov_user_mds_data.

New llapi interfaces llapi_get_lum_file(), llapi_get_lum_dir(),
llapi_get_lum_file_fd(), llapi_get_lum_dir_fd() are added to fetch
valid stat() attributes and LOV info to the user.

Signed-off-by: Qian Yingjin <qian@ddn.com>
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I21dfae7c2633dead5d83b438ec340fea4d3ebbe5
Reviewed-on: https://review.whamcloud.com/35167


Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Li Xi <lixi@ddn.com>