wip: ScrubStack next_to_scrub implementation

Presently blocked by CDir scrub_info setup and dentry selection logic
needing to all be written.
FIXUP "mds: ScrubStack: initial skeleton"

Add auth pinning when the dentry is enqueued

Signed-off-by: Greg Farnum <gfarnum@redhat.com>
mdstypes: dentry_key_t: add an is_valid() function

Wrap up checks for whether the dentry has actually been initialized
to contain any data.

Signed-off-by: Greg Farnum <gfarnum@redhat.com>
mds: CInode: add scrub_info_t intrastructure

Add initialize_scrub() and the scrub_info() accessor.

Signed-off-by: Greg Farnum <gfarnum@redhat.com>
pieces of ScrubStack

Bunches of code to handle the next dentry selection. Still working
on delving down into directories appropriately.

Signed-off-by: Greg Farnum <gfarnum@redhat.com>
mds: CDir: set up initialize_scrub()

It needs to be called after loading the complete directory into
memory.

Signed-off-by: Greg Farnum <gfarnum@redhat.com>
FIXUP "mds: CDir: create scrub_info_t"

Just a comment clarification

Signed-off-by: Greg Farnum <gfarnum@redhat.com>
more ScrubStack pieces

Making good progress on dentry selection for scrubbing.

Signed-off-by: Greg Farnum <gfarnum@redhat.com>
mds: ScrubStack: finish the dentry selection logic? Maybe?

Signed-off-by: Greg Farnum <gfarnum@redhat.com>