Implement a pool lookup by name.  This will be used by rbd.
Signed-off-by: NYehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: NSage Weil <sage@newdream.net>

OSD requests need to be resubmitted on any pg mapping change, not just when
the pg primary changes.  Resending only when the primary changes results in
occasional 'hung' requests during osd cluster recovery or rebalancing.
Signed-off-by: NSage Weil <sage@newdream.net>

Teach the client to decode an updated format for the osdmap.  The new
format includes pool names, which will be useful shortly.  Get this change
in earlier rather than later.
Signed-off-by: NSage Weil <sage@newdream.net>

Since we can now create and destroy pg pools, the pool ids will be sparse,
and an array no longer makes sense for looking up by pool id.  Use an
rbtree instead.

The OSDMap encoding also no longer has a max pool count (previously used to
allocate the array).  There is a new pool_max, that is the largest pool id
we've ever used, although we don't actually need it in the client.
Signed-off-by: NSage Weil <sage@newdream.net>

The endian conversions don't quite work with the old union ceph_pg.  Just
make it a regular struct, and make each field __le.  This is simpler and it
has the added bonus of actually working.
Signed-off-by: NSage Weil <sage@newdream.net>

The OSD client is responsible for reading and writing data from/to the
object storage pool.  This includes determining where objects are
stored in the cluster, and ensuring that requests are retried or
redirected in the event of a node failure or data migration.

If an OSD does not respond before a timeout expires, keepalive
messages are sent across the lossless, ordered communications channel
to ensure that any break in the TCP is discovered.  If the session
does reset, a reconnection is attempted and affected requests are
resent (by the message transport layer).
Signed-off-by: NSage Weil <sage@newdream.net>