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