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raid6: fix recovery performance regression

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The raid6 recovery code should immediately drop back to the optimized
synchronous path when a p+q dma resource is not available.  Otherwise we
run the non-optimized/multi-pass async code in sync mode.

Verified with raid6test (NDISKS=255)

Applies to kernels >= 2.6.32.

Cc: <stable@kernel.org>
Acked-by: NeilBrown <neilb@suse.de>
Reported-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dan Williams 2010-05-04 20:41:56 -07:00 committed by Linus Torvalds
parent 7ebd467551
commit 5157b4aa5b
1 changed files with 13 additions and 8 deletions
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21
crypto/async_tx/async_raid6_recov.c
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@ -324,6 +324,7 @@ struct dma_async_tx_descriptor *
async_raid6_2data_recov(int disks, size_t bytes, int faila, int failb,
struct page **blocks, struct async_submit_ctl *submit)
{
void *scribble = submit->scribble;
int non_zero_srcs, i;
BUG_ON(faila == failb);
@ -332,11 +333,13 @@ async_raid6_2data_recov(int disks, size_t bytes, int faila, int failb,
pr_debug("%s: disks: %d len: %zu\n", __func__, disks, bytes);
/* we need to preserve the contents of 'blocks' for the async
* case, so punt to synchronous if a scribble buffer is not available
/* if a dma resource is not available or a scribble buffer is not
* available punt to the synchronous path. In the 'dma not
* available' case be sure to use the scribble buffer to
* preserve the content of 'blocks' as the caller intended.
*/
if (!submit->scribble) {
void **ptrs = (void **) blocks;
if (!async_dma_find_channel(DMA_PQ) || !scribble) {
void **ptrs = scribble ? scribble : (void **) blocks;
async_tx_quiesce(&submit->depend_tx);
for (i = 0; i < disks; i++)
@ -406,11 +409,13 @@ async_raid6_datap_recov(int disks, size_t bytes, int faila,
pr_debug("%s: disks: %d len: %zu\n", __func__, disks, bytes);
/* we need to preserve the contents of 'blocks' for the async
* case, so punt to synchronous if a scribble buffer is not available
/* if a dma resource is not available or a scribble buffer is not
* available punt to the synchronous path. In the 'dma not
* available' case be sure to use the scribble buffer to
* preserve the content of 'blocks' as the caller intended.
*/
if (!scribble) {
void **ptrs = (void **) blocks;
if (!async_dma_find_channel(DMA_PQ) || !scribble) {
void **ptrs = scribble ? scribble : (void **) blocks;
async_tx_quiesce(&submit->depend_tx);
for (i = 0; i < disks; i++)