1) add IOC_OBD_SNAP_ADD
3) mirror s_flags in sb for P_DIROPS

1)some fix for snap
2)add snap_add command

1)some fix in fsfilt_snap_ext3 and fsfilt_snap_smfs.
2)add smfs_cow.c in smfs.
3)remove snapfs in Makefile.in and configure.in

  #8 from CMD acceptance series

VS: ----------------------------------------------------------------------

  lock on part of dir only
- minor API changes to pass the lock pointer

- configure script sets HAVE_LOOKUP_RAW if kernel has the feature

  then it doesn't take exclusive lock on it; in the meantime another client
  can enlarge directory and 1st client will run splitting w/o exclusive lock

- additional debug message

- test 4a of sanity-lmv.sh to check this case

  this should prevent lookup serialization
- vfs-pdirops-2.4.20-rh.patch exports lock_dir() and unlock_dir() primitives

lock handle which was never used

the group field, which LASSERTs on the OST.

striping default code was removed from mds_crceate_objects

r=rread
A quick workaround for bug 3652, in which we hold the logging
semaphore across an rpc.  Robert thinks that this file can be cleaned
up substantially, but that this fix is sufficient for CMD.