raid6: fix recovery performance regression
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>
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@ -324,6 +324,7 @@ struct dma_async_tx_descriptor *
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async_raid6_2data_recov(int disks, size_t bytes, int faila, int failb,
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async_raid6_2data_recov(int disks, size_t bytes, int faila, int failb,
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struct page **blocks, struct async_submit_ctl *submit)
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struct page **blocks, struct async_submit_ctl *submit)
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{
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{
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void *scribble = submit->scribble;
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int non_zero_srcs, i;
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int non_zero_srcs, i;
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BUG_ON(faila == failb);
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BUG_ON(faila == failb);
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@ -332,11 +333,13 @@ async_raid6_2data_recov(int disks, size_t bytes, int faila, int failb,
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pr_debug("%s: disks: %d len: %zu\n", __func__, disks, bytes);
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pr_debug("%s: disks: %d len: %zu\n", __func__, disks, bytes);
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/* we need to preserve the contents of 'blocks' for the async
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/* if a dma resource is not available or a scribble buffer is not
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* case, so punt to synchronous if a scribble buffer is not available
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* available punt to the synchronous path. In the 'dma not
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* available' case be sure to use the scribble buffer to
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* preserve the content of 'blocks' as the caller intended.
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*/
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*/
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if (!submit->scribble) {
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if (!async_dma_find_channel(DMA_PQ) || !scribble) {
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void **ptrs = (void **) blocks;
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void **ptrs = scribble ? scribble : (void **) blocks;
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async_tx_quiesce(&submit->depend_tx);
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async_tx_quiesce(&submit->depend_tx);
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for (i = 0; i < disks; i++)
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for (i = 0; i < disks; i++)
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@ -406,11 +409,13 @@ async_raid6_datap_recov(int disks, size_t bytes, int faila,
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pr_debug("%s: disks: %d len: %zu\n", __func__, disks, bytes);
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pr_debug("%s: disks: %d len: %zu\n", __func__, disks, bytes);
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/* we need to preserve the contents of 'blocks' for the async
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/* if a dma resource is not available or a scribble buffer is not
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* case, so punt to synchronous if a scribble buffer is not available
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* available punt to the synchronous path. In the 'dma not
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* available' case be sure to use the scribble buffer to
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* preserve the content of 'blocks' as the caller intended.
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*/
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*/
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if (!scribble) {
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if (!async_dma_find_channel(DMA_PQ) || !scribble) {
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void **ptrs = (void **) blocks;
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void **ptrs = scribble ? scribble : (void **) blocks;
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async_tx_quiesce(&submit->depend_tx);
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async_tx_quiesce(&submit->depend_tx);
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for (i = 0; i < disks; i++)
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for (i = 0; i < disks; i++)
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