Commit 0a82a623 authored by Dan Williams's avatar Dan Williams
Browse files

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: default avatarAndre Noll <maan@systemlinux.org>
Acked-by: default avatarMaciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent b2f46fd8

Documentation/crypto/async-tx-api.txt

+4 −0
Original line number Diff line number Diff line
@@ -67,6 +67,10 @@ xor_val - xor a series of source buffers and set a flag if the 
pq	- generate the p+q (raid6 syndrome) from a series of source buffers

pq_val  - validate that a p and or q buffer are in sync with a given series of

	  sources

datap	- (raid6_datap_recov) recover a raid6 data block and the p block

	  from the given sources

2data	- (raid6_2data_recov) recover 2 raid6 data blocks from the given

	  sources



3.3 Descriptor management:

The return value is non-NULL and points to a 'descriptor' when the operation

crypto/async_tx/Kconfig

+5 −0
Original line number Diff line number Diff line
@@ -18,3 +18,8 @@ config ASYNC_PQ 
	tristate

	select ASYNC_CORE



config ASYNC_RAID6_RECOV

	tristate

	select ASYNC_CORE

	select ASYNC_PQ

crypto/async_tx/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -3,3 +3,4 @@ obj-$(CONFIG_ASYNC_MEMCPY) += async_memcpy.o 
obj-$(CONFIG_ASYNC_MEMSET) += async_memset.o

obj-$(CONFIG_ASYNC_XOR) += async_xor.o

obj-$(CONFIG_ASYNC_PQ) += async_pq.o

obj-$(CONFIG_ASYNC_RAID6_RECOV) += async_raid6_recov.o

crypto/async_tx/async_raid6_recov.c

0 → 100644
+448 −0
Original line number Diff line number Diff line 
/*

 * 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");

include/linux/async_tx.h

+8 −0
Original line number Diff line number Diff line
@@ -194,5 +194,13 @@ async_syndrome_val(struct page **blocks, unsigned int offset, int src_cnt, 
		   size_t len, enum sum_check_flags *pqres, struct page *spare,

		   struct async_submit_ctl *submit);



struct dma_async_tx_descriptor *

async_raid6_2data_recov(int src_num, size_t bytes, int faila, int failb,

			struct page **ptrs, struct async_submit_ctl *submit);



struct dma_async_tx_descriptor *

async_raid6_datap_recov(int src_num, size_t bytes, int faila,

			struct page **ptrs, struct async_submit_ctl *submit);



void async_tx_quiesce(struct dma_async_tx_descriptor **tx);

#endif /* _ASYNC_TX_H_ */

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