async_tx: add support for asynchronous RAID6 recovery operations
async_raid6_2data_recov() recovers two data disk failures
async_raid6_datap_recov() recovers a data disk and the P disk
These routines are a port of the synchronous versions found in
drivers/md/raid6recov.c. The primary difference is breaking out the xor
operations into separate calls to async_xor. Two helper routines are
introduced to perform scalar multiplication where needed.
async_sum_product() multiplies two sources by scalar coefficients and
then sums (xor) the result. async_mult() simply multiplies a single
source by a scalar.
This implemention also includes, in contrast to the original
synchronous-only code, special case handling for the 4-disk and 5-disk
array cases. In these situations the default N-disk algorithm will
present 0-source or 1-source operations to dma devices. To cover for
dma devices where the minimum source count is 2 we implement 4-disk and
5-disk handling in the recovery code.
[ Impact: asynchronous raid6 recovery routines for 2data and datap cases ]
Cc: Yuri Tikhonov <yur@emcraft.com>
Cc: Ilya Yanok <yanok@emcraft.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: David Woodhouse <David.Woodhouse@intel.com>
Reviewed-by: Andre Noll <maan@systemlinux.org>
Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/crypto/async_tx/async_raid6_recov.c b/crypto/async_tx/async_raid6_recov.c
new file mode 100644
index 0000000..0c14d48
--- /dev/null
+++ b/crypto/async_tx/async_raid6_recov.c
@@ -0,0 +1,448 @@
+/*
+ * 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/dma-mapping.h>
+#include <linux/raid/pq.h>
+#include <linux/async_tx.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;
+ const u8 *amul, *bmul;
+ u8 ax, bx;
+ u8 *a, *b, *c;
+
+ if (dma) {
+ dma_addr_t dma_dest[2];
+ dma_addr_t dma_src[2];
+ struct device *dev = dma->dev;
+ struct dma_async_tx_descriptor *tx;
+ enum dma_ctrl_flags dma_flags = DMA_PREP_PQ_DISABLE_P;
+
+ dma_dest[1] = dma_map_page(dev, dest, 0, len, DMA_BIDIRECTIONAL);
+ dma_src[0] = dma_map_page(dev, srcs[0], 0, len, DMA_TO_DEVICE);
+ dma_src[1] = dma_map_page(dev, srcs[1], 0, len, DMA_TO_DEVICE);
+ tx = dma->device_prep_dma_pq(chan, dma_dest, dma_src, 2, coef,
+ len, dma_flags);
+ if (tx) {
+ async_tx_submit(chan, tx, submit);
+ return tx;
+ }
+ }
+
+ /* 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;
+ const u8 *qmul; /* Q multiplier table */
+ u8 *d, *s;
+
+ if (dma) {
+ dma_addr_t dma_dest[2];
+ dma_addr_t dma_src[1];
+ struct device *dev = dma->dev;
+ struct dma_async_tx_descriptor *tx;
+ enum dma_ctrl_flags dma_flags = DMA_PREP_PQ_DISABLE_P;
+
+ dma_dest[1] = dma_map_page(dev, dest, 0, len, DMA_BIDIRECTIONAL);
+ dma_src[0] = dma_map_page(dev, src, 0, len, DMA_TO_DEVICE);
+ tx = dma->device_prep_dma_pq(chan, dma_dest, dma_src, 1, &coef,
+ len, dma_flags);
+ if (tx) {
+ async_tx_submit(chan, tx, submit);
+ return tx;
+ }
+ }
+
+ /* 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(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[4-2];
+ q = blocks[4-1];
+
+ 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, 0, 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(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 uninitialized_var(good);
+ int i;
+
+ for (i = 0; i < 3; i++) {
+ if (i == faila || i == failb)
+ continue;
+ else {
+ good = i;
+ break;
+ }
+ }
+ BUG_ON(i >= 3);
+
+ p = blocks[5-2];
+ q = blocks[5-1];
+ 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, 0, tx, NULL, NULL, scribble);
+ tx = async_memcpy(dp, g, 0, 0, bytes, submit);
+ init_async_submit(submit, 0, 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_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_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, 0, 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] = (void *)raid6_empty_zero_page;
+ blocks[disks-2] = dp;
+ dq = blocks[failb];
+ blocks[failb] = (void *)raid6_empty_zero_page;
+ blocks[disks-1] = dq;
+
+ init_async_submit(submit, 0, 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_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_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, 0, 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)
+{
+ BUG_ON(faila == failb);
+ if (failb < faila)
+ swap(faila, 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 (!submit->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_2data_recov(disks, bytes, faila, failb, ptrs);
+
+ async_tx_sync_epilog(submit);
+
+ return NULL;
+ }
+
+ switch (disks) {
+ case 4:
+ /* dma devices do not uniformly understand a zero source pq
+ * operation (in contrast to the synchronous case), so
+ * explicitly handle the 4 disk special case
+ */
+ return __2data_recov_4(bytes, faila, failb, blocks, submit);
+ case 5:
+ /* dma devices do not uniformly understand a single
+ * source pq operation (in contrast to the synchronous
+ * case), so explicitly handle the 5 disk special case
+ */
+ return __2data_recov_5(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;
+ struct page *srcs[2];
+
+ 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 (!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");
