[PATCH 0/6] rbd: old patches from Josh

[Alex Elder <elder@inktank.com>]

Late last year Josh Durgin had put together a series of
fixes for rbd that never got committed.  I told him I
would get them in, and this series represents the last
six that remain.

Here's a summary:
[PATCH 1/6] rbd: return errors for mapped but deleted snapshot
    This adds code to distinguish the result of attempting
    to read data from a deleted snapshot from the the result
    of reading a hole in a snapshot.  The former now produces
    ENXIO.
[PATCH 2/6] rbd: only reset capacity when pointing to head
    When an rbd header is refreshed, its capacity is set in
    case it has been changed.  This should not happen for
    mapped snapshots.
[PATCH 3/6] rbd: expose the correct size of the device in sysfs
    An rbd_dev--even one mapping a snashot--holds the size of
    it's base image in its header's image_size field.  The sysfs
    entry for the snapshot size was showing the wrong value.
[PATCH 4/6] rbd: set image size when header is updated
    The rbd image size was not getting updated when a header
    was refrehsed.
[PATCH 5/6] rbd: use reference counting for the snap context
    This makes sure the rbd code takes a reference to its
    snapshot context while a request related to that context
    is underway.
[PATCH 6/6] rbd: send header version when notifying
    This ensures the version that gets sent back on a watch
    notify acknowledgement is the one that got read as
    a result of refreshing the header.

I've reviewed them all, but am posting them for a chance for
others to comment before I commit them.

					-Alex