[RFC PATCH 00/11][v2] md: support for asynchronous execution of RAID6 operations

[Yuri Tikhonov]

 Hello,

 This is the next attempt on asynchronous RAID-6 support. This patch-set
has the Dan Williams' comments (Nov, 15) addressed. These were mainly
about the ASYNC_TX part of the code.

 The following patch-set includes enhancements to the async_tx api and
modifications to md-raid6 to issue memory copies and parity calculations
asynchronously. Thus we may process copy operations and RAID-6 calculations
on the dedicated DMA engines accessible with ASYNC_TX API, and, as a result
off-load CPU, and improve the performance.

 To reduce the code duplication in the raid driver this patch-set modifies
some raid-5 functions to make them possible to use in the raid-6 case.

 The patch-set can be broken down into thee following main categories: 

1) Additions to ASYNC_TX API (patches 1-3; without the patch 1 the ASYNC_TX
can't be compiled for 44x in 2.6.27-rc6 or later);

2) RAID-6 implementation (patches 4-10)

3) ppc440spe ADMA driver (patch 11) (provided as a reference here)

-- 
Yuri Tikhonov, Senior Software Engineer
Emcraft Systems, www.emcraft.com