Gather on-going resync information of other nodes

When a node joins, it does not know of other nodes performing resync.
So, each node keeps the resync information in it's LVB. When a new
node joins, it reads the LVB of each "online" bitmap.

[TODO] The new node attempts to get the PW lock on other bitmap, if
it is successful, it reads the bitmap and performs the resync (if
required) on it's behalf.

If the node does not get the PW, it requests CR and reads the LVB
for the resync information.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>

diff --cc drivers/md/md-cluster.c
Simple merge

diff --cc drivers/md/md-cluster.h
Simple merge

diff --cc drivers/md/md.c
Simple merge