Fix duplicate filesystem feature flag (matches -fc3 kernel).
r=alex

 - for unknown yet reason, ptlrpc_client_replied() returns true while
   rq_repmsg isn't allocated yet. this causes oops. the patch checks
   the both and outputs debug info

alloc/free rpcpipe path dynamically.

 - lmv_enqueue() should re-enqueue lock if first MDS stores a name only

Disable 71 in sanity.sh, because mmap code is not update on HEAD now.

- fixed sys_umount() code path. It did not release intent what caused memory leaks in sanity-gns.sh, as it uses umount for cleanups while testing GNS.
- do not free intent in GNS case if it is not lookup_it, only drop lock.
- added test_3a which checks disabling GNS mount point using chmod u-s

simplified/rewrite some logic in ll_revalidate_it(), pls back this
out if any problem found.

  that as an error and broke the recovery state machine

- more fixes and comments about intent managing in ll_revalidate_it(). In few words, in the cases dentry is valid and no lookup will be called anymore, intent may be released by ll_intent_release() with clobering -._magic, ->it_op, etc, as it will not be used anymore. In the case revalidate failed, intent should not clobber ->magic, as it will confuse ll_frob_intent() called from ll_lookup_it(). Instead ll_drop_intent_lock() and ll_intent_free() should be used.

- in the case we found potential GNS dentry we do not cause GNS mountining by returning 0 from revalidate if GNS is disabled. This fixes possible NFS stales in some cases.

- added comments about all the changes. Added comment for some GNS related cases.
- in the GNS case lookup intent should be released and others should be dropped and freed.

same problem of bug 6273?)

miss release  parent pdir locks in mds_open

- using IT_CHDIR in sys_chdir() vfs-intent_api-vanilla-2.6.10-fc3.patch. This fixes GNS with cd into mnt point.

- different fixes in GNS stuff.
- gns_enabled flag is moved to separate space instead of using LL_GNS_DISABLED
- removed error messages after inode_setattr(). Only comment is added.
- many changes in sanity-gns.sh, added checks for "cd" case. Deadlock tests are disabled for a while.

 - to avoid possible lock collision during replay, we should replay all
   request before any locks

 - workaround for cascading timeouts when failure of 1 server node causes
   failures of unrelated connections. this caused different problems. for
   example, lock cancel timeouts.

 - reconnect after recovery to all mds nodes. otherwise some mds will
   miss reconnect after recovery and get to recovery timeout situation

 - deadlock in mds_open() fixed: if dentry points to another node, we
   took LOOKUP lock holding UPDATE on a parent while strict resourse-
   -based ordering must be used

replace mds1 with SINGLEMDS according to andreas advice

luster installed, which cause confusion of which lconf/lmc/lctl will be
used. We put $LUSTRE/utils and $LUSTRE/tests at the head of $PATH env
to ensure the tools in source tree will be searched at first. This should
not affect the tests by install, but if we got problem we'll back this
commit out.

- added IT_GETATTR to check if mount should be performed (experimental)

  - sleep_on() is known to be racy replacing it with OBD_SLEEP_ON()
  - added OBD_SLEEP_ON() which is inspired by wait_event() macro.
  - inter_module_{get|put}() replaced with symbol_{get|put}()

- fixes in GNS stuff:
  - ll_revalidate_it() calls missed ll_intent_release() in the case
    GNS dentry is found (fix for #6176)

  - added ll_gns_send_signal() which is needed to cause syscall restarting in the
    case of -ERESTARTSYS is returned.

  - cleanups in ll_gns_mount_object()

  - ll_gns_mount_object() does not wait unconditionaly for userspace upcall,
    instead it give it some time to complete (10s) and returns error if it
    did not mount dentry. This fixes the case when upcall script runs endless
    loop and never returns. This also fixes possible deadlock if another thread
    with wait on not finished mount (this schema is disabled by and -ERESTARTSYS
    is used instead. Both, waiting aproach and -ERESTARTSYS one need more
    investigation).

  - handling result of inode_setattr() call. Printing error message on error.
    This fixes wanings that result of calling this function should be checked.

  - fixed debug message about GNS inabilty to mount dentry (missed arg to CDEBUG
    format string)

  - cleanups in obdfilter_init()
  - fixed using "mount" command in sanity-gns.sh

some fix in replay-single.sh
b:6068

missing up in mds_open_by_id
b:6068

LiangZheng should already have a fix for this.

clean .depend files as well