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async_tx: add support for asynchronous RAID6 recovery operations

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async_raid6_2data_recov() recovers two data disk failures

 async_raid6_datap_recov() recovers a data disk and the P disk

These routines are a port of the synchronous versions found in
drivers/md/raid6recov.c.  The primary difference is breaking out the xor
operations into separate calls to async_xor.  Two helper routines are
introduced to perform scalar multiplication where needed.
async_sum_product() multiplies two sources by scalar coefficients and
then sums (xor) the result.  async_mult() simply multiplies a single
source by a scalar.

This implemention also includes, in contrast to the original
synchronous-only code, special case handling for the 4-disk and 5-disk
array cases.  In these situations the default N-disk algorithm will
present 0-source or 1-source operations to dma devices.  To cover for
dma devices where the minimum source count is 2 we implement 4-disk and
5-disk handling in the recovery code.

[ Impact: asynchronous raid6 recovery routines for 2data and datap cases ]

Cc: Yuri Tikhonov <[email protected]>
Cc: Ilya Yanok <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: David Woodhouse <[email protected]>
Reviewed-by: Andre Noll <[email protected]>
Acked-by: Maciej Sosnowski <[email protected]>
Signed-off-by: Dan Williams <[email protected]>
This commit is contained in:
Dan Williams 2009-07-14 12:20:37 -07:00
commit 0a82a6239b
5 changed files with 466 additions and 0 deletions
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4
Documentation/crypto/async-tx-api.txt
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@ -67,6 +67,10 @@ xor_val - xor a series of source buffers and set a flag if the
pq - generate the p+q (raid6 syndrome) from a series of source buffers
pq_val - validate that a p and or q buffer are in sync with a given series of
sources
datap - (raid6_datap_recov) recover a raid6 data block and the p block
from the given sources
2data - (raid6_2data_recov) recover 2 raid6 data blocks from the given
sources
3.3 Descriptor management:
The return value is non-NULL and points to a 'descriptor' when the operation