Add basic support for RBD_FEATURE_EXCLUSIVE_LOCK feature.  Maintenance
operations (resize, snapshot create, etc) are offloaded to librbd via
returning -EOPNOTSUPP - librbd should request the lock and execute the
operation.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Mike Christie <mchristi@redhat.com>
Tested-by: Mike Christie <mchristi@redhat.com>

This adds support and switches rbd to a new, more reliable version of
watch/notify protocol.  As with the OSD client update, this is mostly
about getting the right structures linked into the right places so that
reconnects are properly sent when needed.  watch/notify v2 also
requires sending regular pings to the OSDs - send_linger_ping().

A major change from the old watch/notify implementation is the
introduction of ceph_osd_linger_request - linger requests no longer
piggy back on ceph_osd_request.  ceph_osd_event has been merged into
ceph_osd_linger_request.

All the details are now hidden within libceph, the interface consists
of a simple pair of watch/unwatch functions and ceph_osdc_notify_ack().
ceph_osdc_watch() does return ceph_osd_linger_request, but only to keep
the lifetime management simple.

ceph_osdc_notify_ack() accepts an optional data payload, which is
relayed back to the notifier.

Portions of this patch are loosely based on work by Douglas Fuller
<dfuller@redhat.com> and Mike Christie <michaelc@cs.wisc.edu>.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

On Mon, Dec 22, 2014 at 5:35 PM, Sage Weil <sage@newdream.net> wrote:
> On Mon, 22 Dec 2014, Ilya Dryomov wrote:
>> Actually, pool op stuff has been unused for over two years - looks like
>> it was added for rbd create_snap and that got ripped out in 2012.  It's
>> unlikely we'd ever need to manage pools or snaps from the kernel client
>> so I think it makes sense to nuke it.  Sage?
>
> Yep!

Signed-off-by: Ilya Dryomov <idryomov@redhat.com>

Bring in missing osd ops and strings, use macros to eliminate multiple
points of maintenance.

Signed-off-by: Ilya Dryomov <idryomov@redhat.com>
Reviewed-by: Sage Weil <sage@redhat.com>

Update ceph_osd_op_name() to include the newly-added definitions in
"rados.h", and to match its counterpart in the user space code.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

Add the definition of ceph_osd_state_name(), to match its
counterpart in user space.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

This factors out protocol and low-level storage parts of ceph into a
separate libceph module living in net/ceph and include/linux/ceph.  This
is mostly a matter of moving files around.  However, a few key pieces
of the interface change as well:

 - ceph_client becomes ceph_fs_client and ceph_client, where the latter
   captures the mon and osd clients, and the fs_client gets the mds client
   and file system specific pieces.
 - Mount option parsing and debugfs setup is correspondingly broken into
   two pieces.
 - The mon client gets a generic handler callback for otherwise unknown
   messages (mds map, in this case).
 - The basic supported/required feature bits can be expanded (and are by
   ceph_fs_client).

No functional change, aside from some subtle error handling cases that got
cleaned up in the refactoring process.

Signed-off-by: Sage Weil <sage@newdream.net>