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

Mix the preferred osd (if any) into the placement seed that is fed into
the CRUSH object placement calculation.  This prevents all the placement
pgs from peering with the same osds.

Rev the osd client protocol with this change.
Signed-off-by: NSage Weil <sage@newdream.net>

Defined a struct for the SUBSCRIBE_ACK, and use that to size
the msgpool.
Signed-off-by: NSage Weil <sage@newdream.net>

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

This tracks updates to code shared with userspace.
Signed-off-by: NSage Weil <sage@newdream.net>

The mon request headers now include session_mon information that must
be properly initialized.
Signed-off-by: NSage Weil <sage@newdream.net>

These headers describe the types used to exchange messages between the
Ceph client and various servers.  All types are little-endian and
packed.  These headers are shared between the kernel and userspace, so
all types are in terms of e.g. __u32.

Additionally, we define a few magic values to identify the current
version of the protocol(s) in use, so that discrepancies to be
detected on mount.
Signed-off-by: NSage Weil <sage@newdream.net>