SQUASH: Revert "mds: ensure that change_attr reflects metadata changes on clients...

SQUASH: Revert "mds: ensure that change_attr reflects metadata changes on clients that hold CAP_FILE_EXCL"

This reverts commit 26ab2fa10041ce34b25aa1535715131a2709a27f.

I don't think this is necessary. We don't necessarily need to increment
the change attribute on every change, as long as we ensure that it gets
bumped iff there were changes since the last time you queried for it.

IOW: it's ok to have a single change_attr change encompass a large set
of changes, as long as you ensure that that it is larger by at least 1
after all of those changes.

In order to look at (and potentially cache) other attributes under that
change_attribute (e.g. owner or mode), you need to recall any outstanding
exclusive caps for those attrs. That causes their change_attrs to be
synched to the largest, which is enough to ensure that it changed in
some way.

Signed-off-by: Jeff Layton <jlayton@redhat.com>