456 lines
13 KiB
C
456 lines
13 KiB
C
/*
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* Asynchronous RAID-6 recovery calculations ASYNC_TX API.
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* Copyright(c) 2009 Intel Corporation
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*
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* based on raid6recov.c:
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* Copyright 2002 H. Peter Anvin
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc., 51
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* Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
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*
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*/
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#include <linux/kernel.h>
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#include <linux/interrupt.h>
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#include <linux/dma-mapping.h>
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#include <linux/raid/pq.h>
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#include <linux/async_tx.h>
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static struct dma_async_tx_descriptor *
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async_sum_product(struct page *dest, struct page **srcs, unsigned char *coef,
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size_t len, struct async_submit_ctl *submit)
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{
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struct dma_chan *chan = async_tx_find_channel(submit, DMA_PQ,
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&dest, 1, srcs, 2, len);
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struct dma_device *dma = chan ? chan->device : NULL;
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const u8 *amul, *bmul;
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u8 ax, bx;
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u8 *a, *b, *c;
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if (dma) {
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dma_addr_t dma_dest[2];
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dma_addr_t dma_src[2];
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struct device *dev = dma->dev;
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struct dma_async_tx_descriptor *tx;
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enum dma_ctrl_flags dma_flags = DMA_PREP_PQ_DISABLE_P;
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if (submit->flags & ASYNC_TX_FENCE)
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dma_flags |= DMA_PREP_FENCE;
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dma_dest[1] = dma_map_page(dev, dest, 0, len, DMA_BIDIRECTIONAL);
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dma_src[0] = dma_map_page(dev, srcs[0], 0, len, DMA_TO_DEVICE);
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dma_src[1] = dma_map_page(dev, srcs[1], 0, len, DMA_TO_DEVICE);
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tx = dma->device_prep_dma_pq(chan, dma_dest, dma_src, 2, coef,
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len, dma_flags);
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if (tx) {
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async_tx_submit(chan, tx, submit);
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return tx;
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}
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}
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/* run the operation synchronously */
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async_tx_quiesce(&submit->depend_tx);
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amul = raid6_gfmul[coef[0]];
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bmul = raid6_gfmul[coef[1]];
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a = page_address(srcs[0]);
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b = page_address(srcs[1]);
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c = page_address(dest);
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while (len--) {
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ax = amul[*a++];
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bx = bmul[*b++];
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*c++ = ax ^ bx;
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}
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return NULL;
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}
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static struct dma_async_tx_descriptor *
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async_mult(struct page *dest, struct page *src, u8 coef, size_t len,
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struct async_submit_ctl *submit)
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{
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struct dma_chan *chan = async_tx_find_channel(submit, DMA_PQ,
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&dest, 1, &src, 1, len);
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struct dma_device *dma = chan ? chan->device : NULL;
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const u8 *qmul; /* Q multiplier table */
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u8 *d, *s;
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if (dma) {
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dma_addr_t dma_dest[2];
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dma_addr_t dma_src[1];
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struct device *dev = dma->dev;
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struct dma_async_tx_descriptor *tx;
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enum dma_ctrl_flags dma_flags = DMA_PREP_PQ_DISABLE_P;
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if (submit->flags & ASYNC_TX_FENCE)
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dma_flags |= DMA_PREP_FENCE;
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dma_dest[1] = dma_map_page(dev, dest, 0, len, DMA_BIDIRECTIONAL);
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dma_src[0] = dma_map_page(dev, src, 0, len, DMA_TO_DEVICE);
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tx = dma->device_prep_dma_pq(chan, dma_dest, dma_src, 1, &coef,
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len, dma_flags);
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if (tx) {
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async_tx_submit(chan, tx, submit);
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return tx;
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}
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}
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/* no channel available, or failed to allocate a descriptor, so
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* perform the operation synchronously
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*/
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async_tx_quiesce(&submit->depend_tx);
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qmul = raid6_gfmul[coef];
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d = page_address(dest);
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s = page_address(src);
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while (len--)
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*d++ = qmul[*s++];
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return NULL;
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}
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static struct dma_async_tx_descriptor *
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__2data_recov_4(size_t bytes, int faila, int failb, struct page **blocks,
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struct async_submit_ctl *submit)
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{
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struct dma_async_tx_descriptor *tx = NULL;
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struct page *p, *q, *a, *b;
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struct page *srcs[2];
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unsigned char coef[2];
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enum async_tx_flags flags = submit->flags;
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dma_async_tx_callback cb_fn = submit->cb_fn;
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void *cb_param = submit->cb_param;
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void *scribble = submit->scribble;
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p = blocks[4-2];
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q = blocks[4-1];
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a = blocks[faila];
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b = blocks[failb];
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/* in the 4 disk case P + Pxy == P and Q + Qxy == Q */
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/* Dx = A*(P+Pxy) + B*(Q+Qxy) */
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srcs[0] = p;
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srcs[1] = q;
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coef[0] = raid6_gfexi[failb-faila];
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coef[1] = raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]];
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init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble);
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tx = async_sum_product(b, srcs, coef, bytes, submit);
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/* Dy = P+Pxy+Dx */
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srcs[0] = p;
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srcs[1] = b;
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init_async_submit(submit, flags | ASYNC_TX_XOR_ZERO_DST, tx, cb_fn,
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cb_param, scribble);
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tx = async_xor(a, srcs, 0, 2, bytes, submit);
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return tx;
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}
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static struct dma_async_tx_descriptor *
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__2data_recov_5(size_t bytes, int faila, int failb, struct page **blocks,
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struct async_submit_ctl *submit)
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{
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struct dma_async_tx_descriptor *tx = NULL;
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struct page *p, *q, *g, *dp, *dq;
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struct page *srcs[2];
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unsigned char coef[2];
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enum async_tx_flags flags = submit->flags;
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dma_async_tx_callback cb_fn = submit->cb_fn;
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void *cb_param = submit->cb_param;
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void *scribble = submit->scribble;
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int uninitialized_var(good);
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int i;
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for (i = 0; i < 3; i++) {
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if (i == faila || i == failb)
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continue;
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else {
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good = i;
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break;
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}
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}
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BUG_ON(i >= 3);
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p = blocks[5-2];
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q = blocks[5-1];
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g = blocks[good];
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/* Compute syndrome with zero for the missing data pages
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* Use the dead data pages as temporary storage for delta p and
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* delta q
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*/
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dp = blocks[faila];
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dq = blocks[failb];
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init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble);
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tx = async_memcpy(dp, g, 0, 0, bytes, submit);
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init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble);
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tx = async_mult(dq, g, raid6_gfexp[good], bytes, submit);
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/* compute P + Pxy */
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srcs[0] = dp;
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srcs[1] = p;
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init_async_submit(submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
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NULL, NULL, scribble);
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tx = async_xor(dp, srcs, 0, 2, bytes, submit);
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/* compute Q + Qxy */
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srcs[0] = dq;
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srcs[1] = q;
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init_async_submit(submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
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NULL, NULL, scribble);
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tx = async_xor(dq, srcs, 0, 2, bytes, submit);
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/* Dx = A*(P+Pxy) + B*(Q+Qxy) */
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srcs[0] = dp;
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srcs[1] = dq;
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coef[0] = raid6_gfexi[failb-faila];
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coef[1] = raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]];
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init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble);
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tx = async_sum_product(dq, srcs, coef, bytes, submit);
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/* Dy = P+Pxy+Dx */
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srcs[0] = dp;
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srcs[1] = dq;
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init_async_submit(submit, flags | ASYNC_TX_XOR_DROP_DST, tx, cb_fn,
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cb_param, scribble);
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tx = async_xor(dp, srcs, 0, 2, bytes, submit);
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return tx;
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}
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static struct dma_async_tx_descriptor *
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__2data_recov_n(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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{
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struct dma_async_tx_descriptor *tx = NULL;
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struct page *p, *q, *dp, *dq;
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struct page *srcs[2];
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unsigned char coef[2];
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enum async_tx_flags flags = submit->flags;
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dma_async_tx_callback cb_fn = submit->cb_fn;
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void *cb_param = submit->cb_param;
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void *scribble = submit->scribble;
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p = blocks[disks-2];
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q = blocks[disks-1];
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/* Compute syndrome with zero for the missing data pages
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* Use the dead data pages as temporary storage for
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* delta p and delta q
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*/
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dp = blocks[faila];
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blocks[faila] = (void *)raid6_empty_zero_page;
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blocks[disks-2] = dp;
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dq = blocks[failb];
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blocks[failb] = (void *)raid6_empty_zero_page;
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blocks[disks-1] = dq;
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init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble);
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tx = async_gen_syndrome(blocks, 0, disks, bytes, submit);
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/* Restore pointer table */
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blocks[faila] = dp;
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blocks[failb] = dq;
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blocks[disks-2] = p;
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blocks[disks-1] = q;
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/* compute P + Pxy */
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srcs[0] = dp;
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srcs[1] = p;
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init_async_submit(submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
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NULL, NULL, scribble);
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tx = async_xor(dp, srcs, 0, 2, bytes, submit);
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/* compute Q + Qxy */
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srcs[0] = dq;
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srcs[1] = q;
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init_async_submit(submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
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NULL, NULL, scribble);
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tx = async_xor(dq, srcs, 0, 2, bytes, submit);
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/* Dx = A*(P+Pxy) + B*(Q+Qxy) */
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srcs[0] = dp;
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srcs[1] = dq;
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coef[0] = raid6_gfexi[failb-faila];
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coef[1] = raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]];
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init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble);
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tx = async_sum_product(dq, srcs, coef, bytes, submit);
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/* Dy = P+Pxy+Dx */
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srcs[0] = dp;
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srcs[1] = dq;
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init_async_submit(submit, flags | ASYNC_TX_XOR_DROP_DST, tx, cb_fn,
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cb_param, scribble);
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tx = async_xor(dp, srcs, 0, 2, bytes, submit);
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return tx;
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}
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/**
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* async_raid6_2data_recov - asynchronously calculate two missing data blocks
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* @disks: number of disks in the RAID-6 array
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* @bytes: block size
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* @faila: first failed drive index
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* @failb: second failed drive index
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* @blocks: array of source pointers where the last two entries are p and q
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* @submit: submission/completion modifiers
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*/
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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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struct page **blocks, struct async_submit_ctl *submit)
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{
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BUG_ON(faila == failb);
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if (failb < faila)
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swap(faila, failb);
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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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* case, so punt to synchronous if a scribble buffer is not available
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*/
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if (!submit->scribble) {
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void **ptrs = (void **) blocks;
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int i;
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async_tx_quiesce(&submit->depend_tx);
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for (i = 0; i < disks; i++)
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ptrs[i] = page_address(blocks[i]);
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raid6_2data_recov(disks, bytes, faila, failb, ptrs);
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async_tx_sync_epilog(submit);
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return NULL;
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}
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switch (disks) {
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case 4:
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/* dma devices do not uniformly understand a zero source pq
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* operation (in contrast to the synchronous case), so
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* explicitly handle the 4 disk special case
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*/
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return __2data_recov_4(bytes, faila, failb, blocks, submit);
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case 5:
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/* dma devices do not uniformly understand a single
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* source pq operation (in contrast to the synchronous
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* case), so explicitly handle the 5 disk special case
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*/
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return __2data_recov_5(bytes, faila, failb, blocks, submit);
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default:
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return __2data_recov_n(disks, bytes, faila, failb, blocks, submit);
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}
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}
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EXPORT_SYMBOL_GPL(async_raid6_2data_recov);
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/**
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* async_raid6_datap_recov - asynchronously calculate a data and the 'p' block
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* @disks: number of disks in the RAID-6 array
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* @bytes: block size
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* @faila: failed drive index
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* @blocks: array of source pointers where the last two entries are p and q
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* @submit: submission/completion modifiers
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*/
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struct dma_async_tx_descriptor *
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async_raid6_datap_recov(int disks, size_t bytes, int faila,
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struct page **blocks, struct async_submit_ctl *submit)
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{
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struct dma_async_tx_descriptor *tx = NULL;
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struct page *p, *q, *dq;
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u8 coef;
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enum async_tx_flags flags = submit->flags;
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dma_async_tx_callback cb_fn = submit->cb_fn;
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void *cb_param = submit->cb_param;
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void *scribble = submit->scribble;
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struct page *srcs[2];
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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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* case, so punt to synchronous if a scribble buffer is not available
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*/
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if (!scribble) {
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void **ptrs = (void **) blocks;
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int i;
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async_tx_quiesce(&submit->depend_tx);
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for (i = 0; i < disks; i++)
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ptrs[i] = page_address(blocks[i]);
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raid6_datap_recov(disks, bytes, faila, ptrs);
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async_tx_sync_epilog(submit);
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return NULL;
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}
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p = blocks[disks-2];
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q = blocks[disks-1];
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/* Compute syndrome with zero for the missing data page
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* Use the dead data page as temporary storage for delta q
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*/
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dq = blocks[faila];
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blocks[faila] = (void *)raid6_empty_zero_page;
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blocks[disks-1] = dq;
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/* in the 4 disk case we only need to perform a single source
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* multiplication
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*/
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if (disks == 4) {
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int good = faila == 0 ? 1 : 0;
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struct page *g = blocks[good];
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init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL,
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scribble);
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tx = async_memcpy(p, g, 0, 0, bytes, submit);
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init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL,
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scribble);
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tx = async_mult(dq, g, raid6_gfexp[good], bytes, submit);
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} else {
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init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL,
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scribble);
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tx = async_gen_syndrome(blocks, 0, disks, bytes, submit);
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}
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/* Restore pointer table */
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blocks[faila] = dq;
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blocks[disks-1] = q;
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/* calculate g^{-faila} */
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coef = raid6_gfinv[raid6_gfexp[faila]];
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srcs[0] = dq;
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srcs[1] = q;
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init_async_submit(submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
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NULL, NULL, scribble);
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tx = async_xor(dq, srcs, 0, 2, bytes, submit);
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init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble);
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tx = async_mult(dq, dq, coef, bytes, submit);
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srcs[0] = p;
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srcs[1] = dq;
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init_async_submit(submit, flags | ASYNC_TX_XOR_DROP_DST, tx, cb_fn,
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cb_param, scribble);
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tx = async_xor(p, srcs, 0, 2, bytes, submit);
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return tx;
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}
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EXPORT_SYMBOL_GPL(async_raid6_datap_recov);
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MODULE_AUTHOR("Dan Williams <dan.j.williams@intel.com>");
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MODULE_DESCRIPTION("asynchronous RAID-6 recovery api");
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MODULE_LICENSE("GPL");
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