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+/*
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+
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+ return NULL;
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+}
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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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+
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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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+
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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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+
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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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+
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+ while (len--)
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+ *d++ = qmul[*s++];
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+
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+ return NULL;
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+}
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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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+
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+ p = blocks[4-2];
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+ q = blocks[4-1];
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+
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+ a = blocks[faila];
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+ b = blocks[failb];
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+
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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, 0, tx, NULL, NULL, scribble);
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+ tx = async_sum_product(b, srcs, coef, bytes, submit);
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+
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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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+
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+ return tx;
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+
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+}
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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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+
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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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+
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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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+
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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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+
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+ init_async_submit(submit, 0, 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, 0, tx, NULL, NULL, scribble);
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+ tx = async_mult(dq, g, raid6_gfexp[good], bytes, submit);
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+
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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_XOR_DROP_DST, tx, NULL, NULL,
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+ scribble);
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+ tx = async_xor(dp, srcs, 0, 2, bytes, submit);
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+
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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_XOR_DROP_DST, tx, NULL, NULL,
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+ scribble);
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+ tx = async_xor(dq, srcs, 0, 2, bytes, submit);
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+
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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, 0, tx, NULL, NULL, scribble);
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+ tx = async_sum_product(dq, srcs, coef, bytes, submit);
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+
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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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+
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+ return tx;
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+}
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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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+
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+ p = blocks[disks-2];
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+ q = blocks[disks-1];
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+
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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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+
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+ init_async_submit(submit, 0, tx, NULL, NULL, 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] = 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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+
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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_XOR_DROP_DST, tx, NULL, NULL,
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+ scribble);
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+ tx = async_xor(dp, srcs, 0, 2, bytes, submit);
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+
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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_XOR_DROP_DST, tx, NULL, NULL,
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+ scribble);
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+ tx = async_xor(dq, srcs, 0, 2, bytes, submit);
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+
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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, 0, tx, NULL, NULL, scribble);
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+ tx = async_sum_product(dq, srcs, coef, bytes, submit);
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+
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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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+
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+ return tx;
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+}
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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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+
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+ pr_debug("%s: disks: %d len: %zu\n", __func__, disks, bytes);
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+
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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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+
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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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+
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+ raid6_2data_recov(disks, bytes, faila, failb, ptrs);
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+
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+ async_tx_sync_epilog(submit);
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+
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+ return NULL;
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+ }
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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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+/**
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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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+
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+ pr_debug("%s: disks: %d len: %zu\n", __func__, disks, bytes);
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+
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+ /* we need to preserve the contents of 'blocks' for the async
|
|
|
+ * case, so punt to synchronous if a scribble buffer is not available
|
|
|
+ */
|
|
|
+ if (!scribble) {
|
|
|
+ void **ptrs = (void **) blocks;
|
|
|
+ int i;
|
|
|
+
|
|
|
+ async_tx_quiesce(&submit->depend_tx);
|
|
|
+ for (i = 0; i < disks; i++)
|
|
|
+ ptrs[i] = page_address(blocks[i]);
|
|
|
+
|
|
|
+ raid6_datap_recov(disks, bytes, faila, ptrs);
|
|
|
+
|
|
|
+ async_tx_sync_epilog(submit);
|
|
|
+
|
|
|
+ return NULL;
|
|
|
+ }
|
|
|
+
|
|
|
+ p = blocks[disks-2];
|
|
|
+ q = blocks[disks-1];
|
|
|
+
|
|
|
+ /* Compute syndrome with zero for the missing data page
|
|
|
+ * Use the dead data page as temporary storage for delta q
|
|
|
+ */
|
|
|
+ dq = blocks[faila];
|
|
|
+ blocks[faila] = (void *)raid6_empty_zero_page;
|
|
|
+ blocks[disks-1] = dq;
|
|
|
+
|
|
|
+ /* in the 4 disk case we only need to perform a single source
|
|
|
+ * multiplication
|
|
|
+ */
|
|
|
+ if (disks == 4) {
|
|
|
+ int good = faila == 0 ? 1 : 0;
|
|
|
+ struct page *g = blocks[good];
|
|
|
+
|
|
|
+ init_async_submit(submit, 0, tx, NULL, NULL, scribble);
|
|
|
+ tx = async_memcpy(p, g, 0, 0, bytes, submit);
|
|
|
+
|
|
|
+ init_async_submit(submit, 0, tx, NULL, NULL, scribble);
|
|
|
+ tx = async_mult(dq, g, raid6_gfexp[good], bytes, submit);
|
|
|
+ } else {
|
|
|
+ init_async_submit(submit, 0, tx, NULL, NULL, scribble);
|
|
|
+ tx = async_gen_syndrome(blocks, 0, disks, bytes, submit);
|
|
|
+ }
|
|
|
+
|
|
|
+ /* Restore pointer table */
|
|
|
+ blocks[faila] = dq;
|
|
|
+ blocks[disks-1] = q;
|
|
|
+
|
|
|
+ /* calculate g^{-faila} */
|
|
|
+ coef = raid6_gfinv[raid6_gfexp[faila]];
|
|
|
+
|
|
|
+ srcs[0] = dq;
|
|
|
+ srcs[1] = q;
|
|
|
+ init_async_submit(submit, ASYNC_TX_XOR_DROP_DST, tx, NULL, NULL,
|
|
|
+ scribble);
|
|
|
+ tx = async_xor(dq, srcs, 0, 2, bytes, submit);
|
|
|
+
|
|
|
+ init_async_submit(submit, 0, tx, NULL, NULL, scribble);
|
|
|
+ tx = async_mult(dq, dq, coef, bytes, submit);
|
|
|
+
|
|
|
+ srcs[0] = p;
|
|
|
+ srcs[1] = dq;
|
|
|
+ init_async_submit(submit, flags | ASYNC_TX_XOR_DROP_DST, tx, cb_fn,
|
|
|
+ cb_param, scribble);
|
|
|
+ tx = async_xor(p, srcs, 0, 2, bytes, submit);
|
|
|
+
|
|
|
+ return tx;
|
|
|
+}
|
|
|
+EXPORT_SYMBOL_GPL(async_raid6_datap_recov);
|
|
|
+
|
|
|
+MODULE_AUTHOR("Dan Williams <dan.j.williams@intel.com>");
|
|
|
+MODULE_DESCRIPTION("asynchronous RAID-6 recovery api");
|
|
|
+MODULE_LICENSE("GPL");
|