[PATCH 0 of 9] MD: Updates for dm-raid.c support

[Jonathan Brassow <jbrassow@f14.redhat.com>]

Neil,

The following set of 9 patches is composed of three sets:
1) Patches 1-6 are small updates and fixes to what is already in the kernel.
2) Patch 7 introduces a new superblock type for device-mapper - allowing it
to record failures and give future support for reshaping and bitmap use.
3) Patches 8-9 provide bitmap support.  Patch 9 is necessary for transient failures,
where the bitmap can be replayed to recover a disk that has been gone for a short
time.  Without patch 9, raid5 will simply force a complete resync.

The first set by itself fixes a couple issues and protects against the      
possibility that dm-raid.c attempts to utilize super_types that may not exist.
The addition of the second set provides a working solution that is useful to
LVM in addition to (userspace) dm-raid.  The final set is not absolutely   
necessary, but provides the obvious recovery speed-up.

I have seen an issue related to the MD recovery thread starting up before the
bitmap has been properly loaded.  This issue is not a result of this patchset,
nor is it addressed by this patch set.  Until I find a way to fix this issue,
the 3rd set may be problematic and we may wish to defer it until I have a 
solution.

 brassow