Fix the mds_bmap_ensure_valid() assert: If we don't write here, the ios add logic won't write either because it does not sense a change in the IOS assignment. And we end up writing bmap without writing the inode table. Some time later, we read the bmap in response to a lease request, but we find the number of replicas is zero even if the bmap says otherwise.
Fix the mds_bmap_ensure_valid() assert: If we don't write here, the
ios add logic won't write either because it does not sense a change
in the IOS assignment. And we end up writing bmap without writing
the inode table. Some time later, we read the bmap in response to
a lease request, but we find the number of replicas is zero even if
the bmap says otherwise.

pscedu/slash2-stable,pscedu/slash2-stable,pscedu/slash2-stable,pscedu/slash2-stable,pscedu/slash2-stable,pscedu/slash2-stable,pscedu/slash2-stable