Merge branch 'md-raid6-accel' into ioat3.2

Conflicts:
	include/linux/dmaengine.h

23 files changed, 2528 insertions, 927 deletions

diff --git a/Documentation/crypto/async-tx-api.txt b/Documentation/crypto/async-tx-api.txt
index 9f59fcb..ba046b8 100644
--- a/Documentation/crypto/async-tx-api.txt
+++ b/Documentation/crypto/async-tx-api.txt
@@ -54,20 +54,23 @@ features surfaced as a result:
 
 3.1 General format of the API:
 struct dma_async_tx_descriptor *
-async_<operation>(<op specific parameters>,
-		  enum async_tx_flags flags,
-        	  struct dma_async_tx_descriptor *dependency,
-        	  dma_async_tx_callback callback_routine,
-		  void *callback_parameter);
+async_<operation>(<op specific parameters>, struct async_submit ctl *submit)
 
 3.2 Supported operations:
-memcpy       - memory copy between a source and a destination buffer
-memset       - fill a destination buffer with a byte value
-xor          - xor a series of source buffers and write the result to a
-	       destination buffer
-xor_zero_sum - xor a series of source buffers and set a flag if the
-	       result is zero.  The implementation attempts to prevent
-	       writes to memory
+memcpy  - memory copy between a source and a destination buffer
+memset  - fill a destination buffer with a byte value
+xor     - xor a series of source buffers and write the result to a
+	  destination buffer
+xor_val - xor a series of source buffers and set a flag if the
+	  result is zero.  The implementation attempts to prevent
+	  writes to memory
+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
@@ -80,8 +83,8 @@ acknowledged by the application before the offload engine driver is allowed to
 recycle (or free) the descriptor.  A descriptor can be acked by one of the
 following methods:
 1/ setting the ASYNC_TX_ACK flag if no child operations are to be submitted
-2/ setting the ASYNC_TX_DEP_ACK flag to acknowledge the parent
-   descriptor of a new operation.
+2/ submitting an unacknowledged descriptor as a dependency to another
+   async_tx call will implicitly set the acknowledged state.
 3/ calling async_tx_ack() on the descriptor.
 
 3.4 When does the operation execute?
@@ -119,30 +122,42 @@ of an operation.
 Perform a xor->copy->xor operation where each operation depends on the
 result from the previous operation:
 
-void complete_xor_copy_xor(void *param)
+void callback(void *param)
 {
-	printk("complete\n");
+	struct completion *cmp = param;
+
+	complete(cmp);
 }
 
-int run_xor_copy_xor(struct page **xor_srcs,
-		     int xor_src_cnt,
-		     struct page *xor_dest,
-		     size_t xor_len,
-		     struct page *copy_src,
-		     struct page *copy_dest,
-		     size_t copy_len)
+void run_xor_copy_xor(struct page **xor_srcs,
+		      int xor_src_cnt,
+		      struct page *xor_dest,
+		      size_t xor_len,
+		      struct page *copy_src,
+		      struct page *copy_dest,
+		      size_t copy_len)
 {
 	struct dma_async_tx_descriptor *tx;
+	addr_conv_t addr_conv[xor_src_cnt];
+	struct async_submit_ctl submit;
+	addr_conv_t addr_conv[NDISKS];
+	struct completion cmp;
+
+	init_async_submit(&submit, ASYNC_TX_XOR_DROP_DST, NULL, NULL, NULL,
+			  addr_conv);
+	tx = async_xor(xor_dest, xor_srcs, 0, xor_src_cnt, xor_len, &submit)
 
-	tx = async_xor(xor_dest, xor_srcs, 0, xor_src_cnt, xor_len,
-		       ASYNC_TX_XOR_DROP_DST, NULL, NULL, NULL);
-	tx = async_memcpy(copy_dest, copy_src, 0, 0, copy_len,
-			  ASYNC_TX_DEP_ACK, tx, NULL, NULL);
-	tx = async_xor(xor_dest, xor_srcs, 0, xor_src_cnt, xor_len,
-		       ASYNC_TX_XOR_DROP_DST | ASYNC_TX_DEP_ACK | ASYNC_TX_ACK,
-		       tx, complete_xor_copy_xor, NULL);
+	submit->depend_tx = tx;
+	tx = async_memcpy(copy_dest, copy_src, 0, 0, copy_len, &submit);
+
+	init_completion(&cmp);
+	init_async_submit(&submit, ASYNC_TX_XOR_DROP_DST | ASYNC_TX_ACK, tx,
+			  callback, &cmp, addr_conv);
+	tx = async_xor(xor_dest, xor_srcs, 0, xor_src_cnt, xor_len, &submit);
 
 	async_tx_issue_pending_all();
+
+	wait_for_completion(&cmp);
 }
 
 See include/linux/async_tx.h for more information on the flags.  See the
diff --git a/arch/arm/include/asm/hardware/iop3xx-adma.h b/arch/arm/include/asm/hardware/iop3xx-adma.h
index 83e6ba3..26eefea 100644
--- a/arch/arm/include/asm/hardware/iop3xx-adma.h
+++ b/arch/arm/include/asm/hardware/iop3xx-adma.h
@@ -756,13 +756,14 @@ static inline void iop_desc_set_block_fill_val(struct iop_adma_desc_slot *desc,
 	hw_desc->src[0] = val;
 }
 
-static inline int iop_desc_get_zero_result(struct iop_adma_desc_slot *desc)
+static inline enum sum_check_flags
+iop_desc_get_zero_result(struct iop_adma_desc_slot *desc)
 {
 	struct iop3xx_desc_aau *hw_desc = desc->hw_desc;
 	struct iop3xx_aau_desc_ctrl desc_ctrl = hw_desc->desc_ctrl_field;
 
 	iop_paranoia(!(desc_ctrl.tx_complete && desc_ctrl.zero_result_en));
-	return desc_ctrl.zero_result_err;
+	return desc_ctrl.zero_result_err << SUM_CHECK_P;
 }
 
 static inline void iop_chan_append(struct iop_adma_chan *chan)
diff --git a/arch/arm/mach-iop13xx/include/mach/adma.h b/arch/arm/mach-iop13xx/include/mach/adma.h
index 5722e86..1cd31df8 100644
--- a/arch/arm/mach-iop13xx/include/mach/adma.h
+++ b/arch/arm/mach-iop13xx/include/mach/adma.h
@@ -428,18 +428,20 @@ static inline void iop_desc_set_block_fill_val(struct iop_adma_desc_slot *desc,
 	hw_desc->block_fill_data = val;
 }
 
-static inline int iop_desc_get_zero_result(struct iop_adma_desc_slot *desc)
+static inline enum sum_check_flags
+iop_desc_get_zero_result(struct iop_adma_desc_slot *desc)
 {
 	struct iop13xx_adma_desc_hw *hw_desc = desc->hw_desc;
 	struct iop13xx_adma_desc_ctrl desc_ctrl = hw_desc->desc_ctrl_field;
 	struct iop13xx_adma_byte_count byte_count = hw_desc->byte_count_field;
+	enum sum_check_flags flags;
 
 	BUG_ON(!(byte_count.tx_complete && desc_ctrl.zero_result));
 
-	if (desc_ctrl.pq_xfer_en)
-		return byte_count.zero_result_err_q;
-	else
-		return byte_count.zero_result_err;
+	flags = byte_count.zero_result_err_q << SUM_CHECK_Q;
+	flags |= byte_count.zero_result_err << SUM_CHECK_P;
+
+	return flags;
 }
 
 static inline void iop_chan_append(struct iop_adma_chan *chan)
diff --git a/arch/arm/mach-iop13xx/setup.c b/arch/arm/mach-iop13xx/setup.c
index bee42c6..faaef95 100644
--- a/arch/arm/mach-iop13xx/setup.c
+++ b/arch/arm/mach-iop13xx/setup.c
@@ -478,7 +478,7 @@ void __init iop13xx_platform_init(void)
 			dma_cap_set(DMA_MEMCPY, plat_data->cap_mask);
 			dma_cap_set(DMA_XOR, plat_data->cap_mask);
 			dma_cap_set(DMA_DUAL_XOR, plat_data->cap_mask);
-			dma_cap_set(DMA_ZERO_SUM, plat_data->cap_mask);
+			dma_cap_set(DMA_XOR_VAL, plat_data->cap_mask);
 			dma_cap_set(DMA_MEMSET, plat_data->cap_mask);
 			dma_cap_set(DMA_MEMCPY_CRC32C, plat_data->cap_mask);
 			dma_cap_set(DMA_INTERRUPT, plat_data->cap_mask);
@@ -490,7 +490,7 @@ void __init iop13xx_platform_init(void)
 			dma_cap_set(DMA_MEMCPY, plat_data->cap_mask);
 			dma_cap_set(DMA_XOR, plat_data->cap_mask);
 			dma_cap_set(DMA_DUAL_XOR, plat_data->cap_mask);
-			dma_cap_set(DMA_ZERO_SUM, plat_data->cap_mask);
+			dma_cap_set(DMA_XOR_VAL, plat_data->cap_mask);
 			dma_cap_set(DMA_MEMSET, plat_data->cap_mask);
 			dma_cap_set(DMA_MEMCPY_CRC32C, plat_data->cap_mask);
 			dma_cap_set(DMA_INTERRUPT, plat_data->cap_mask);
@@ -502,13 +502,13 @@ void __init iop13xx_platform_init(void)
 			dma_cap_set(DMA_MEMCPY, plat_data->cap_mask);
 			dma_cap_set(DMA_XOR, plat_data->cap_mask);
 			dma_cap_set(DMA_DUAL_XOR, plat_data->cap_mask);
-			dma_cap_set(DMA_ZERO_SUM, plat_data->cap_mask);
+			dma_cap_set(DMA_XOR_VAL, plat_data->cap_mask);
 			dma_cap_set(DMA_MEMSET, plat_data->cap_mask);
 			dma_cap_set(DMA_MEMCPY_CRC32C, plat_data->cap_mask);
 			dma_cap_set(DMA_INTERRUPT, plat_data->cap_mask);
-			dma_cap_set(DMA_PQ_XOR, plat_data->cap_mask);
+			dma_cap_set(DMA_PQ, plat_data->cap_mask);
 			dma_cap_set(DMA_PQ_UPDATE, plat_data->cap_mask);
-			dma_cap_set(DMA_PQ_ZERO_SUM, plat_data->cap_mask);
+			dma_cap_set(DMA_PQ_VAL, plat_data->cap_mask);
 			break;
 		}
 	}
diff --git a/arch/arm/plat-iop/adma.c b/arch/arm/plat-iop/adma.c
index 3c127aa..da1dd0da 100644
--- a/arch/arm/plat-iop/adma.c
+++ b/arch/arm/plat-iop/adma.c
@@ -198,7 +198,7 @@ static int __init iop3xx_adma_cap_init(void)
 	dma_cap_set(DMA_INTERRUPT, iop3xx_aau_data.cap_mask);
 	#else
 	dma_cap_set(DMA_XOR, iop3xx_aau_data.cap_mask);
-	dma_cap_set(DMA_ZERO_SUM, iop3xx_aau_data.cap_mask);
+	dma_cap_set(DMA_XOR_VAL, iop3xx_aau_data.cap_mask);
 	dma_cap_set(DMA_MEMSET, iop3xx_aau_data.cap_mask);
 	dma_cap_set(DMA_INTERRUPT, iop3xx_aau_data.cap_mask);
 	#endif
diff --git a/crypto/async_tx/Kconfig b/crypto/async_tx/Kconfig
index d8fb3914..e5aeb2b 100644
--- a/crypto/async_tx/Kconfig
+++ b/crypto/async_tx/Kconfig
@@ -14,3 +14,12 @@ config ASYNC_MEMSET
 	tristate
 	select ASYNC_CORE
 
+config ASYNC_PQ
+	tristate
+	select ASYNC_CORE
+
+config ASYNC_RAID6_RECOV
+	tristate
+	select ASYNC_CORE
+	select ASYNC_PQ
+
diff --git a/crypto/async_tx/Makefile b/crypto/async_tx/Makefile
index 27baa7d..d1e0e6f 100644
--- a/crypto/async_tx/Makefile
+++ b/crypto/async_tx/Makefile
@@ -2,3 +2,6 @@ obj-$(CONFIG_ASYNC_CORE) += async_tx.o
 obj-$(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
+obj-$(CONFIG_ASYNC_RAID6_TEST) += raid6test.o
diff --git a/crypto/async_tx/async_memcpy.c b/crypto/async_tx/async_memcpy.c
index ddccfb0..98e15bd 100644
--- a/crypto/async_tx/async_memcpy.c
+++ b/crypto/async_tx/async_memcpy.c
@@ -33,28 +33,28 @@
  * async_memcpy - attempt to copy memory with a dma engine.
  * @dest: destination page
  * @src: src page
- * @offset: offset in pages to start transaction
+ * @dest_offset: offset into 'dest' to start transaction
+ * @src_offset: offset into 'src' to start transaction
  * @len: length in bytes
- * @flags: ASYNC_TX_ACK, ASYNC_TX_DEP_ACK,
- * @depend_tx: memcpy depends on the result of this transaction
- * @cb_fn: function to call when the memcpy completes
- * @cb_param: parameter to pass to the callback routine
+ * @submit: submission / completion modifiers
+ *
+ * honored flags: ASYNC_TX_ACK
  */
 struct dma_async_tx_descriptor *
 async_memcpy(struct page *dest, struct page *src, unsigned int dest_offset,
-	unsigned int src_offset, size_t len, enum async_tx_flags flags,
-	struct dma_async_tx_descriptor *depend_tx,
-	dma_async_tx_callback cb_fn, void *cb_param)
+	     unsigned int src_offset, size_t len,
+	     struct async_submit_ctl *submit)
 {
-	struct dma_chan *chan = async_tx_find_channel(depend_tx, DMA_MEMCPY,
+	struct dma_chan *chan = async_tx_find_channel(submit, DMA_MEMCPY,
 						      &dest, 1, &src, 1, len);
 	struct dma_device *device = chan ? chan->device : NULL;
 	struct dma_async_tx_descriptor *tx = NULL;
 
 	if (device) {
 		dma_addr_t dma_dest, dma_src;
-		unsigned long dma_prep_flags = cb_fn ? DMA_PREP_INTERRUPT : 0;
+		unsigned long dma_prep_flags;
 
+		dma_prep_flags = submit->cb_fn ? DMA_PREP_INTERRUPT : 0;
 		dma_dest = dma_map_page(device->dev, dest, dest_offset, len,
 					DMA_FROM_DEVICE);
 
@@ -67,13 +67,13 @@ async_memcpy(struct page *dest, struct page *src, unsigned int dest_offset,
 
 	if (tx) {
 		pr_debug("%s: (async) len: %zu\n", __func__, len);
-		async_tx_submit(chan, tx, flags, depend_tx, cb_fn, cb_param);
+		async_tx_submit(chan, tx, submit);
 	} else {
 		void *dest_buf, *src_buf;
 		pr_debug("%s: (sync) len: %zu\n", __func__, len);
 
 		/* wait for any prerequisite operations */
-		async_tx_quiesce(&depend_tx);
+		async_tx_quiesce(&submit->depend_tx);
 
 		dest_buf = kmap_atomic(dest, KM_USER0) + dest_offset;
 		src_buf = kmap_atomic(src, KM_USER1) + src_offset;
@@ -83,26 +83,13 @@ async_memcpy(struct page *dest, struct page *src, unsigned int dest_offset,
 		kunmap_atomic(dest_buf, KM_USER0);
 		kunmap_atomic(src_buf, KM_USER1);
 
-		async_tx_sync_epilog(cb_fn, cb_param);
+		async_tx_sync_epilog(submit);
 	}
 
 	return tx;
 }
 EXPORT_SYMBOL_GPL(async_memcpy);
 
-static int __init async_memcpy_init(void)
-{
-	return 0;
-}
-
-static void __exit async_memcpy_exit(void)
-{
-	do { } while (0);
-}
-
-module_init(async_memcpy_init);
-module_exit(async_memcpy_exit);
-
 MODULE_AUTHOR("Intel Corporation");
 MODULE_DESCRIPTION("asynchronous memcpy api");
 MODULE_LICENSE("GPL");
diff --git a/crypto/async_tx/async_memset.c b/crypto/async_tx/async_memset.c
index 5b5eb99..b896a6e 100644
--- a/crypto/async_tx/async_memset.c
+++ b/crypto/async_tx/async_memset.c
@@ -35,26 +35,23 @@
  * @val: fill value
  * @offset: offset in pages to start transaction
  * @len: length in bytes
- * @flags: ASYNC_TX_ACK, ASYNC_TX_DEP_ACK
- * @depend_tx: memset depends on the result of this transaction
- * @cb_fn: function to call when the memcpy completes
- * @cb_param: parameter to pass to the callback routine
+ *
+ * honored flags: ASYNC_TX_ACK
  */
 struct dma_async_tx_descriptor *
-async_memset(struct page *dest, int val, unsigned int offset,
-	size_t len, enum async_tx_flags flags,
-	struct dma_async_tx_descriptor *depend_tx,
-	dma_async_tx_callback cb_fn, void *cb_param)
+async_memset(struct page *dest, int val, unsigned int offset, size_t len,
+	     struct async_submit_ctl *submit)
 {
-	struct dma_chan *chan = async_tx_find_channel(depend_tx, DMA_MEMSET,
+	struct dma_chan *chan = async_tx_find_channel(submit, DMA_MEMSET,
 						      &dest, 1, NULL, 0, len);
 	struct dma_device *device = chan ? chan->device : NULL;
 	struct dma_async_tx_descriptor *tx = NULL;
 
 	if (device) {
 		dma_addr_t dma_dest;
-		unsigned long dma_prep_flags = cb_fn ? DMA_PREP_INTERRUPT : 0;
+		unsigned long dma_prep_flags;
 
+		dma_prep_flags = submit->cb_fn ? DMA_PREP_INTERRUPT : 0;
 		dma_dest = dma_map_page(device->dev, dest, offset, len,
 					DMA_FROM_DEVICE);
 
@@ -64,38 +61,25 @@ async_memset(struct page *dest, int val, unsigned int offset,
 
 	if (tx) {
 		pr_debug("%s: (async) len: %zu\n", __func__, len);
-		async_tx_submit(chan, tx, flags, depend_tx, cb_fn, cb_param);
+		async_tx_submit(chan, tx, submit);
 	} else { /* run the memset synchronously */
 		void *dest_buf;
 		pr_debug("%s: (sync) len: %zu\n", __func__, len);
 
-		dest_buf = (void *) (((char *) page_address(dest)) + offset);
+		dest_buf = page_address(dest) + offset;
 
 		/* wait for any prerequisite operations */
-		async_tx_quiesce(&depend_tx);
+		async_tx_quiesce(&submit->depend_tx);
 
 		memset(dest_buf, val, len);
 
-		async_tx_sync_epilog(cb_fn, cb_param);
+		async_tx_sync_epilog(submit);
 	}
 
 	return tx;
 }
 EXPORT_SYMBOL_GPL(async_memset);
 
-static int __init async_memset_init(void)
-{
-	return 0;
-}
-
-static void __exit async_memset_exit(void)
-{
-	do { } while (0);
-}
-
-module_init(async_memset_init);
-module_exit(async_memset_exit);
-
 MODULE_AUTHOR("Intel Corporation");
 MODULE_DESCRIPTION("asynchronous memset api");
 MODULE_LICENSE("GPL");
diff --git a/crypto/async_tx/async_pq.c b/crypto/async_tx/async_pq.c
new file mode 100644
index 0000000..108b21e
--- /dev/null
+++ b/crypto/async_tx/async_pq.c
@@ -0,0 +1,388 @@
+/*
+ * Copyright(c) 2007 Yuri Tikhonov <yur@emcraft.com>
+ * Copyright(c) 2009 Intel Corporation
+ *
+ * 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., 59
+ * Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ *
+ * The full GNU General Public License is included in this distribution in the
+ * file called COPYING.
+ */
+#include <linux/kernel.h>
+#include <linux/interrupt.h>
+#include <linux/dma-mapping.h>
+#include <linux/raid/pq.h>
+#include <linux/async_tx.h>
+
+/**
+ * scribble - space to hold throwaway P buffer for synchronous gen_syndrome
+ */
+static struct page *scribble;
+
+static bool is_raid6_zero_block(struct page *p)
+{
+	return p == (void *) raid6_empty_zero_page;
+}
+
+/* the struct page *blocks[] parameter passed to async_gen_syndrome()
+ * and async_syndrome_val() contains the 'P' destination address at
+ * blocks[disks-2] and the 'Q' destination address at blocks[disks-1]
+ *
+ * note: these are macros as they are used as lvalues
+ */
+#define P(b, d) (b[d-2])
+#define Q(b, d) (b[d-1])
+
+/**
+ * do_async_gen_syndrome - asynchronously calculate P and/or Q
+ */
+static __async_inline struct dma_async_tx_descriptor *
+do_async_gen_syndrome(struct dma_chan *chan, struct page **blocks,
+		      const unsigned char *scfs, unsigned int offset, int disks,
+		      size_t len, dma_addr_t *dma_src,
+		      struct async_submit_ctl *submit)
+{
+	struct dma_async_tx_descriptor *tx = NULL;
+	struct dma_device *dma = chan->device;
+	enum dma_ctrl_flags dma_flags = 0;
+	enum async_tx_flags flags_orig = submit->flags;
+	dma_async_tx_callback cb_fn_orig = submit->cb_fn;
+	dma_async_tx_callback cb_param_orig = submit->cb_param;
+	int src_cnt = disks - 2;
+	unsigned char coefs[src_cnt];
+	unsigned short pq_src_cnt;
+	dma_addr_t dma_dest[2];
+	int src_off = 0;
+	int idx;
+	int i;
+
+	/* DMAs use destinations as sources, so use BIDIRECTIONAL mapping */
+	if (P(blocks, disks))
+		dma_dest[0] = dma_map_page(dma->dev, P(blocks, disks), offset,
+					   len, DMA_BIDIRECTIONAL);
+	else
+		dma_flags |= DMA_PREP_PQ_DISABLE_P;
+	if (Q(blocks, disks))
+		dma_dest[1] = dma_map_page(dma->dev, Q(blocks, disks), offset,
+					   len, DMA_BIDIRECTIONAL);
+	else
+		dma_flags |= DMA_PREP_PQ_DISABLE_Q;
+
+	/* convert source addresses being careful to collapse 'empty'
+	 * sources and update the coefficients accordingly
+	 */
+	for (i = 0, idx = 0; i < src_cnt; i++) {
+		if (is_raid6_zero_block(blocks[i]))
+			continue;
+		dma_src[idx] = dma_map_page(dma->dev, blocks[i], offset, len,
+					    DMA_TO_DEVICE);
+		coefs[idx] = scfs[i];
+		idx++;
+	}
+	src_cnt = idx;
+
+	while (src_cnt > 0) {
+		submit->flags = flags_orig;
+		pq_src_cnt = min(src_cnt, dma_maxpq(dma, dma_flags));
+		/* if we are submitting additional pqs, leave the chain open,
+		 * clear the callback parameters, and leave the destination
+		 * buffers mapped
+		 */
+		if (src_cnt > pq_src_cnt) {
+			submit->flags &= ~ASYNC_TX_ACK;
+			dma_flags |= DMA_COMPL_SKIP_DEST_UNMAP;
+			submit->cb_fn = NULL;
+			submit->cb_param = NULL;
+		} else {
+			dma_flags &= ~DMA_COMPL_SKIP_DEST_UNMAP;
+			submit->cb_fn = cb_fn_orig;
+			submit->cb_param = cb_param_orig;
+			if (cb_fn_orig)
+				dma_flags |= DMA_PREP_INTERRUPT;
+		}
+
+		/* Since we have clobbered the src_list we are committed
+		 * to doing this asynchronously.  Drivers force forward
+		 * progress in case they can not provide a descriptor
+		 */
+		for (;;) {
+			tx = dma->device_prep_dma_pq(chan, dma_dest,
+						     &dma_src[src_off],
+						     pq_src_cnt,
+						     &coefs[src_off], len,
+						     dma_flags);
+			if (likely(tx))
+				break;
+			async_tx_quiesce(&submit->depend_tx);
+			dma_async_issue_pending(chan);
+		}
+
+		async_tx_submit(chan, tx, submit);
+		submit->depend_tx = tx;
+
+		/* drop completed sources */
+		src_cnt -= pq_src_cnt;
+		src_off += pq_src_cnt;
+
+		dma_flags |= DMA_PREP_CONTINUE;
+	}
+
+	return tx;
+}
+
+/**
+ * do_sync_gen_syndrome - synchronously calculate a raid6 syndrome
+ */
+static void
+do_sync_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
+		     size_t len, struct async_submit_ctl *submit)
+{
+	void **srcs;
+	int i;
+
+	if (submit->scribble)
+		srcs = submit->scribble;
+	else
+		srcs = (void **) blocks;
+
+	for (i = 0; i < disks; i++) {
+		if (is_raid6_zero_block(blocks[i])) {
+			BUG_ON(i > disks - 3); /* P or Q can't be zero */
+			srcs[i] = blocks[i];
+		} else
+			srcs[i] = page_address(blocks[i]) + offset;
+	}
+	raid6_call.gen_syndrome(disks, len, srcs);
+	async_tx_sync_epilog(submit);
+}
+
+/**
+ * async_gen_syndrome - asynchronously calculate a raid6 syndrome
+ * @blocks: source blocks from idx 0..disks-3, P @ disks-2 and Q @ disks-1
+ * @offset: common offset into each block (src and dest) to start transaction
+ * @disks: number of blocks (including missing P or Q, see below)
+ * @len: length of operation in bytes
+ * @submit: submission/completion modifiers
+ *
+ * General note: This routine assumes a field of GF(2^8) with a
+ * primitive polynomial of 0x11d and a generator of {02}.
+ *
+ * 'disks' note: callers can optionally omit either P or Q (but not
+ * both) from the calculation by setting blocks[disks-2] or
+ * blocks[disks-1] to NULL.  When P or Q is omitted 'len' must be <=
+ * PAGE_SIZE as a temporary buffer of this size is used in the
+ * synchronous path.  'disks' always accounts for both destination
+ * buffers.
+ *
+ * 'blocks' note: if submit->scribble is NULL then the contents of
+ * 'blocks' may be overridden
+ */
+struct dma_async_tx_descriptor *
+async_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
+		   size_t len, struct async_submit_ctl *submit)
+{
+	int src_cnt = disks - 2;
+	struct dma_chan *chan = async_tx_find_channel(submit, DMA_PQ,
+						      &P(blocks, disks), 2,
+						      blocks, src_cnt, len);
+	struct dma_device *device = chan ? chan->device : NULL;
+	dma_addr_t *dma_src = NULL;
+
+	BUG_ON(disks > 255 || !(P(blocks, disks) || Q(blocks, disks)));
+
+	if (submit->scribble)
+		dma_src = submit->scribble;
+	else if (sizeof(dma_addr_t) <= sizeof(struct page *))
+		dma_src = (dma_addr_t *) blocks;
+
+	if (dma_src && device &&
+	    (src_cnt <= dma_maxpq(device, 0) ||
+	     dma_maxpq(device, DMA_PREP_CONTINUE) > 0)) {
+		/* run the p+q asynchronously */
+		pr_debug("%s: (async) disks: %d len: %zu\n",
+			 __func__, disks, len);
+		return do_async_gen_syndrome(chan, blocks, raid6_gfexp, offset,
+					     disks, len, dma_src, submit);
+	}
+
+	/* run the pq synchronously */
+	pr_debug("%s: (sync) disks: %d len: %zu\n", __func__, disks, len);
+
+	/* wait for any prerequisite operations */
+	async_tx_quiesce(&submit->depend_tx);
+
+	if (!P(blocks, disks)) {
+		P(blocks, disks) = scribble;
+		BUG_ON(len + offset > PAGE_SIZE);
+	}
+	if (!Q(blocks, disks)) {
+		Q(blocks, disks) = scribble;
+		BUG_ON(len + offset > PAGE_SIZE);
+	}
+	do_sync_gen_syndrome(blocks, offset, disks, len, submit);
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(async_gen_syndrome);
+
+/**
+ * async_syndrome_val - asynchronously validate a raid6 syndrome
+ * @blocks: source blocks from idx 0..disks-3, P @ disks-2 and Q @ disks-1
+ * @offset: common offset into each block (src and dest) to start transaction
+ * @disks: number of blocks (including missing P or Q, see below)
+ * @len: length of operation in bytes
+ * @pqres: on val failure SUM_CHECK_P_RESULT and/or SUM_CHECK_Q_RESULT are set
+ * @spare: temporary result buffer for the synchronous case
+ * @submit: submission / completion modifiers
+ *
+ * The same notes from async_gen_syndrome apply to the 'blocks',
+ * and 'disks' parameters of this routine.  The synchronous path
+ * requires a temporary result buffer and submit->scribble to be
+ * specified.
+ */
+struct dma_async_tx_descriptor *
+async_syndrome_val(struct page **blocks, unsigned int offset, int disks,
+		   size_t len, enum sum_check_flags *pqres, struct page *spare,
+		   struct async_submit_ctl *submit)
+{
+	struct dma_chan *chan = async_tx_find_channel(submit, DMA_PQ_VAL,
+						      NULL, 0,  blocks, disks,
+						      len);
+	struct dma_device *device = chan ? chan->device : NULL;
+	struct dma_async_tx_descriptor *tx;
+	enum dma_ctrl_flags dma_flags = submit->cb_fn ? DMA_PREP_INTERRUPT : 0;
+	dma_addr_t *dma_src = NULL;
+
+	BUG_ON(disks < 4);
+
+	if (submit->scribble)
+		dma_src = submit->scribble;
+	else if (sizeof(dma_addr_t) <= sizeof(struct page *))
+		dma_src = (dma_addr_t *) blocks;
+
+	if (dma_src && device && disks <= dma_maxpq(device, 0)) {
+		struct device *dev = device->dev;
+		dma_addr_t *pq = &dma_src[disks-2];
+		int i;
+
+		pr_debug("%s: (async) disks: %d len: %zu\n",
+			 __func__, disks, len);
+		if (!P(blocks, disks))
+			dma_flags |= DMA_PREP_PQ_DISABLE_P;
+		if (!Q(blocks, disks))
+			dma_flags |= DMA_PREP_PQ_DISABLE_Q;
+		for (i = 0; i < disks; i++)
+			if (likely(blocks[i])) {
+				BUG_ON(is_raid6_zero_block(blocks[i]));
+				dma_src[i] = dma_map_page(dev, blocks[i],
+							  offset, len,
+							  DMA_TO_DEVICE);
+			}
+
+		for (;;) {
+			tx = device->device_prep_dma_pq_val(chan, pq, dma_src,
+							    disks - 2,
+							    raid6_gfexp,
+							    len, pqres,
+							    dma_flags);
+			if (likely(tx))
+				break;
+			async_tx_quiesce(&submit->depend_tx);
+			dma_async_issue_pending(chan);
+		}
+		async_tx_submit(chan, tx, submit);
+
+		return tx;
+	} else {
+		struct page *p_src = P(blocks, disks);
+		struct page *q_src = Q(blocks, disks);
+		enum async_tx_flags flags_orig = submit->flags;
+		dma_async_tx_callback cb_fn_orig = submit->cb_fn;
+		void *scribble = submit->scribble;
+		void *cb_param_orig = submit->cb_param;
+		void *p, *q, *s;
+
+		pr_debug("%s: (sync) disks: %d len: %zu\n",
+			 __func__, disks, len);
+
+		/* caller must provide a temporary result buffer and
+		 * allow the input parameters to be preserved
+		 */
+		BUG_ON(!spare || !scribble);
+
+		/* wait for any prerequisite operations */
+		async_tx_quiesce(&submit->depend_tx);
+
+		/* recompute p and/or q into the temporary buffer and then
+		 * check to see the result matches the current value
+		 */
+		tx = NULL;
+		*pqres = 0;
+		if (p_src) {
+			init_async_submit(submit, ASYNC_TX_XOR_ZERO_DST, NULL,
+					  NULL, NULL, scribble);
+			tx = async_xor(spare, blocks, offset, disks-2, len, submit);
+			async_tx_quiesce(&tx);
+			p = page_address(p_src) + offset;
+			s = page_address(spare) + offset;
+			*pqres |= !!memcmp(p, s, len) << SUM_CHECK_P;
+		}
+
+		if (q_src) {
+			P(blocks, disks) = NULL;
+			Q(blocks, disks) = spare;
+			init_async_submit(submit, 0, NULL, NULL, NULL, scribble);
+			tx = async_gen_syndrome(blocks, offset, disks, len, submit);
+			async_tx_quiesce(&tx);
+			q = page_address(q_src) + offset;
+			s = page_address(spare) + offset;
+			*pqres |= !!memcmp(q, s, len) << SUM_CHECK_Q;
+		}
+
+		/* restore P, Q and submit */
+		P(blocks, disks) = p_src;
+		Q(blocks, disks) = q_src;
+
+		submit->cb_fn = cb_fn_orig;
+		submit->cb_param = cb_param_orig;
+		submit->flags = flags_orig;
+		async_tx_sync_epilog(submit);
+
+		return NULL;
+	}
+}
+EXPORT_SYMBOL_GPL(async_syndrome_val);
+
+static int __init async_pq_init(void)
+{
+	scribble = alloc_page(GFP_KERNEL);
+
+	if (scribble)
+		return 0;
+
+	pr_err("%s: failed to allocate required spare page\n", __func__);
+
+	return -ENOMEM;
+}
+
+static void __exit async_pq_exit(void)
+{
+	put_page(scribble);
+}
+
+module_init(async_pq_init);
+module_exit(async_pq_exit);
+
+MODULE_DESCRIPTION("asynchronous raid6 syndrome generation/validation");
+MODULE_LICENSE("GPL");
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");
diff --git a/crypto/async_tx/async_tx.c b/crypto/async_tx/async_tx.c
index 06eb6cc..60615fe 100644
--- a/crypto/async_tx/async_tx.c
+++ b/crypto/async_tx/async_tx.c
@@ -42,16 +42,21 @@ static void __exit async_tx_exit(void)
 	async_dmaengine_put();
 }
 
+module_init(async_tx_init);
+module_exit(async_tx_exit);
+
 /**
  * __async_tx_find_channel - find a channel to carry out the operation or let
  *	the transaction execute synchronously
- * @depend_tx: transaction dependency
+ * @submit: transaction dependency and submission modifiers
  * @tx_type: transaction type
  */
 struct dma_chan *
-__async_tx_find_channel(struct dma_async_tx_descriptor *depend_tx,
-	enum dma_transaction_type tx_type)
+__async_tx_find_channel(struct async_submit_ctl *submit,
+			enum dma_transaction_type tx_type)
 {
+	struct dma_async_tx_descriptor *depend_tx = submit->depend_tx;
+
 	/* see if we can keep the chain on one channel */
 	if (depend_tx &&
 	    dma_has_cap(tx_type, depend_tx->chan->device->cap_mask))
@@ -59,17 +64,6 @@ __async_tx_find_channel(struct dma_async_tx_descriptor *depend_tx,
 	return async_dma_find_channel(tx_type);
 }
 EXPORT_SYMBOL_GPL(__async_tx_find_channel);
-#else
-static int __init async_tx_init(void)
-{
-	printk(KERN_INFO "async_tx: api initialized (sync-only)\n");
-	return 0;
-}
-
-static void __exit async_tx_exit(void)
-{
-	do { } while (0);
-}
 #endif
 
 
@@ -83,8 +77,8 @@ static void
 async_tx_channel_switch(struct dma_async_tx_descriptor *depend_tx,
 			struct dma_async_tx_descriptor *tx)
 {
-	struct dma_chan *chan;
-	struct dma_device *device;
+	struct dma_chan *chan = depend_tx->chan;
+	struct dma_device *device = chan->device;
 	struct dma_async_tx_descriptor *intr_tx = (void *) ~0;
 
 	/* first check to see if we can still append to depend_tx */
@@ -96,11 +90,11 @@ async_tx_channel_switch(struct dma_async_tx_descriptor *depend_tx,
 	}
 	spin_unlock_bh(&depend_tx->lock);
 
-	if (!intr_tx)
+	/* attached dependency, flush the parent channel */
+	if (!intr_tx) {
+		device->device_issue_pending(chan);
 		return;
-
-	chan = depend_tx->chan;
-	device = chan->device;
+	}
 
 	/* see if we can schedule an interrupt
 	 * otherwise poll for completion
@@ -134,6 +128,7 @@ async_tx_channel_switch(struct dma_async_tx_descriptor *depend_tx,
 			intr_tx->tx_submit(intr_tx);
 			async_tx_ack(intr_tx);
 		}
+		device->device_issue_pending(chan);
 	} else {
 		if (dma_wait_for_async_tx(depend_tx) == DMA_ERROR)
 			panic("%s: DMA_ERROR waiting for depend_tx\n",
@@ -144,13 +139,14 @@ async_tx_channel_switch(struct dma_async_tx_descriptor *depend_tx,
 
 
 /**
- * submit_disposition - while holding depend_tx->lock we must avoid submitting
- * 	new operations to prevent a circular locking dependency with
- * 	drivers that already hold a channel lock when calling
- * 	async_tx_run_dependencies.
+ * submit_disposition - flags for routing an incoming operation
  * @ASYNC_TX_SUBMITTED: we were able to append the new operation under the lock
  * @ASYNC_TX_CHANNEL_SWITCH: when the lock is dropped schedule a channel switch
  * @ASYNC_TX_DIRECT_SUBMIT: when the lock is dropped submit directly
+ *
+ * while holding depend_tx->lock we must avoid submitting new operations
+ * to prevent a circular locking dependency with drivers that already
+ * hold a channel lock when calling async_tx_run_dependencies.
  */
 enum submit_disposition {
 	ASYNC_TX_SUBMITTED,
@@ -160,11 +156,12 @@ enum submit_disposition {
 
 void
 async_tx_submit(struct dma_chan *chan, struct dma_async_tx_descriptor *tx,
-	enum async_tx_flags flags, struct dma_async_tx_descriptor *depend_tx,
-	dma_async_tx_callback cb_fn, void *cb_param)
+		struct async_submit_ctl *submit)
 {
-	tx->callback = cb_fn;
-	tx->callback_param = cb_param;
+	struct dma_async_tx_descriptor *depend_tx = submit->depend_tx;
+
+	tx->callback = submit->cb_fn;
+	tx->callback_param = submit->cb_param;
 
 	if (depend_tx) {
 		enum submit_disposition s;
@@ -220,30 +217,29 @@ async_tx_submit(struct dma_chan *chan, struct dma_async_tx_descriptor *tx,
 		tx->tx_submit(tx);
 	}
 
-	if (flags & ASYNC_TX_ACK)
+	if (submit->flags & ASYNC_TX_ACK)
 		async_tx_ack(tx);
 
-	if (depend_tx && (flags & ASYNC_TX_DEP_ACK))
+	if (depend_tx)
 		async_tx_ack(depend_tx);
 }
 EXPORT_SYMBOL_GPL(async_tx_submit);
 
 /**
- * async_trigger_callback - schedules the callback function to be run after
- * any dependent operations have been completed.
- * @flags: ASYNC_TX_ACK, ASYNC_TX_DEP_ACK
- * @depend_tx: 'callback' requires the completion of this transaction
- * @cb_fn: function to call after depend_tx completes
- * @cb_param: parameter to pass to the callback routine
+ * async_trigger_callback - schedules the callback function to be run
+ * @submit: submission and completion parameters
+ *
+ * honored flags: ASYNC_TX_ACK
+ *
+ * The callback is run after any dependent operations have completed.
  */
 struct dma_async_tx_descriptor *
-async_trigger_callback(enum async_tx_flags flags,
-	struct dma_async_tx_descriptor *depend_tx,
-	dma_async_tx_callback cb_fn, void *cb_param)
+async_trigger_callback(struct async_submit_ctl *submit)
 {
 	struct dma_chan *chan;
 	struct dma_device *device;
 	struct dma_async_tx_descriptor *tx;
+	struct dma_async_tx_descriptor *depend_tx = submit->depend_tx;
 
 	if (depend_tx) {
 		chan = depend_tx->chan;
@@ -262,14 +258,14 @@ async_trigger_callback(enum async_tx_flags flags,
 	if (tx) {
 		pr_debug("%s: (async)\n", __func__);
 
-		async_tx_submit(chan, tx, flags, depend_tx, cb_fn, cb_param);
+		async_tx_submit(chan, tx, submit);
 	} else {
 		pr_debug("%s: (sync)\n", __func__);
 
 		/* wait for any prerequisite operations */
-		async_tx_quiesce(&depend_tx);
+		async_tx_quiesce(&submit->depend_tx);
 
-		async_tx_sync_epilog(cb_fn, cb_param);
+		async_tx_sync_epilog(submit);
 	}
 
 	return tx;
@@ -295,9 +291,6 @@ void async_tx_quiesce(struct dma_async_tx_descriptor **tx)
 }
 EXPORT_SYMBOL_GPL(async_tx_quiesce);
 
-module_init(async_tx_init);
-module_exit(async_tx_exit);
-
 MODULE_AUTHOR("Intel Corporation");
 MODULE_DESCRIPTION("Asynchronous Bulk Memory Transactions API");
 MODULE_LICENSE("GPL");
diff --git a/crypto/async_tx/async_xor.c b/crypto/async_tx/async_xor.c
index 95fe2c8..56b5f98 100644
--- a/crypto/async_tx/async_xor.c
+++ b/crypto/async_tx/async_xor.c
@@ -33,19 +33,16 @@
 /* do_async_xor - dma map the pages and perform the xor with an engine */
 static __async_inline struct dma_async_tx_descriptor *
 do_async_xor(struct dma_chan *chan, struct page *dest, struct page **src_list,
-	     unsigned int offset, int src_cnt, size_t len,
-	     enum async_tx_flags flags,
-	     struct dma_async_tx_descriptor *depend_tx,
-	     dma_async_tx_callback cb_fn, void *cb_param)
+	     unsigned int offset, int src_cnt, size_t len, dma_addr_t *dma_src,
+	     struct async_submit_ctl *submit)
 {
 	struct dma_device *dma = chan->device;
-	dma_addr_t *dma_src = (dma_addr_t *) src_list;
 	struct dma_async_tx_descriptor *tx = NULL;
 	int src_off = 0;
 	int i;
-	dma_async_tx_callback _cb_fn;
-	void *_cb_param;
-	enum async_tx_flags async_flags;
+	dma_async_tx_callback cb_fn_orig = submit->cb_fn;
+	void *cb_param_orig = submit->cb_param;
+	enum async_tx_flags flags_orig = submit->flags;
 	enum dma_ctrl_flags dma_flags;
 	int xor_src_cnt;
 	dma_addr_t dma_dest;
@@ -63,23 +60,23 @@ do_async_xor(struct dma_chan *chan, struct page *dest, struct page **src_list,
 	}
 
 	while (src_cnt) {
-		async_flags = flags;
+		submit->flags = flags_orig;
 		dma_flags = 0;
-		xor_src_cnt = min(src_cnt, dma->max_xor);
+		xor_src_cnt = min(src_cnt, (int)dma->max_xor);
 		/* if we are submitting additional xors, leave the chain open,
 		 * clear the callback parameters, and leave the destination
 		 * buffer mapped
 		 */
 		if (src_cnt > xor_src_cnt) {
-			async_flags &= ~ASYNC_TX_ACK;
+			submit->flags &= ~ASYNC_TX_ACK;
 			dma_flags = DMA_COMPL_SKIP_DEST_UNMAP;
-			_cb_fn = NULL;
-			_cb_param = NULL;
+			submit->cb_fn = NULL;
+			submit->cb_param = NULL;
 		} else {
-			_cb_fn = cb_fn;
-			_cb_param = cb_param;
+			submit->cb_fn = cb_fn_orig;
+			submit->cb_param = cb_param_orig;
 		}
-		if (_cb_fn)
+		if (submit->cb_fn)
 			dma_flags |= DMA_PREP_INTERRUPT;
 
 		/* Since we have clobbered the src_list we are committed
@@ -90,7 +87,7 @@ do_async_xor(struct dma_chan *chan, struct page *dest, struct page **src_list,
 					      xor_src_cnt, len, dma_flags);
 
 		if (unlikely(!tx))
-			async_tx_quiesce(&depend_tx);
+			async_tx_quiesce(&submit->depend_tx);
 
 		/* spin wait for the preceeding transactions to complete */
 		while (unlikely(!tx)) {
@@ -101,11 +98,8 @@ do_async_xor(struct dma_chan *chan, struct page *dest, struct page **src_list,
 						      dma_flags);
 		}
 
-		async_tx_submit(chan, tx, async_flags, depend_tx, _cb_fn,
-				_cb_param);
-
-		depend_tx = tx;
-		flags |= ASYNC_TX_DEP_ACK;
+		async_tx_submit(chan, tx, submit);
+		submit->depend_tx = tx;
 
 		if (src_cnt > xor_src_cnt) {
 			/* drop completed sources */
@@ -124,23 +118,27 @@ do_async_xor(struct dma_chan *chan, struct page *dest, struct page **src_list,
 
 static void
 do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset,
-	    int src_cnt, size_t len, enum async_tx_flags flags,
-	    dma_async_tx_callback cb_fn, void *cb_param)
+	    int src_cnt, size_t len, struct async_submit_ctl *submit)
 {
 	int i;
 	int xor_src_cnt;
 	int src_off = 0;
 	void *dest_buf;
-	void **srcs = (void **) src_list;
+	void **srcs;
+
+	if (submit->scribble)
+		srcs = submit->scribble;
+	else
+		srcs = (void **) src_list;
 
-	/* reuse the 'src_list' array to convert to buffer pointers */
+	/* convert to buffer pointers */
 	for (i = 0; i < src_cnt; i++)
 		srcs[i] = page_address(src_list[i]) + offset;
 
 	/* set destination address */
 	dest_buf = page_address(dest) + offset;
 
-	if (flags & ASYNC_TX_XOR_ZERO_DST)
+	if (submit->flags & ASYNC_TX_XOR_ZERO_DST)
 		memset(dest_buf, 0, len);
 
 	while (src_cnt > 0) {
@@ -153,61 +151,70 @@ do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset,
 		src_off += xor_src_cnt;
 	}
 
-	async_tx_sync_epilog(cb_fn, cb_param);
+	async_tx_sync_epilog(submit);
 }
 
 /**
  * async_xor - attempt to xor a set of blocks with a dma engine.
- *	xor_blocks always uses the dest as a source so the ASYNC_TX_XOR_ZERO_DST
- *	flag must be set to not include dest data in the calculation.  The
- *	assumption with dma eninges is that they only use the destination
- *	buffer as a source when it is explicity specified in the source list.
  * @dest: destination page
- * @src_list: array of source pages (if the dest is also a source it must be
- *	at index zero).  The contents of this array may be overwritten.
- * @offset: offset in pages to start transaction
+ * @src_list: array of source pages
+ * @offset: common src/dst offset to start transaction
  * @src_cnt: number of source pages
  * @len: length in bytes
- * @flags: ASYNC_TX_XOR_ZERO_DST, ASYNC_TX_XOR_DROP_DEST,
- *	ASYNC_TX_ACK, ASYNC_TX_DEP_ACK
- * @depend_tx: xor depends on the result of this transaction.
- * @cb_fn: function to call when the xor completes
- * @cb_param: parameter to pass to the callback routine
+ * @submit: submission / completion modifiers
+ *
+ * honored flags: ASYNC_TX_ACK, ASYNC_TX_XOR_ZERO_DST, ASYNC_TX_XOR_DROP_DST
+ *
+ * xor_blocks always uses the dest as a source so the
+ * ASYNC_TX_XOR_ZERO_DST flag must be set to not include dest data in
+ * the calculation.  The assumption with dma eninges is that they only
+ * use the destination buffer as a source when it is explicity specified
+ * in the source list.
+ *
+ * src_list note: if the dest is also a source it must be at index zero.
+ * The contents of this array will be overwritten if a scribble region
+ * is not specified.
  */
 struct dma_async_tx_descriptor *
 async_xor(struct page *dest, struct page **src_list, unsigned int offset,
-	int src_cnt, size_t len, enum async_tx_flags flags,
-	struct dma_async_tx_descriptor *depend_tx,
-	dma_async_tx_callback cb_fn, void *cb_param)
+	  int src_cnt, size_t len, struct async_submit_ctl *submit)
 {
-	struct dma_chan *chan = async_tx_find_channel(depend_tx, DMA_XOR,
+	struct dma_chan *chan = async_tx_find_channel(submit, DMA_XOR,
 						      &dest, 1, src_list,
 						      src_cnt, len);
+	dma_addr_t *dma_src = NULL;
+
 	BUG_ON(src_cnt <= 1);
 
-	if (chan) {
+	if (submit->scribble)
+		dma_src = submit->scribble;
+	else if (sizeof(dma_addr_t) <= sizeof(struct page *))
+		dma_src = (dma_addr_t *) src_list;
+
+	if (dma_src && chan) {
 		/* run the xor asynchronously */
 		pr_debug("%s (async): len: %zu\n", __func__, len);
 
 		return do_async_xor(chan, dest, src_list, offset, src_cnt, len,
-				    flags, depend_tx, cb_fn, cb_param);
+				    dma_src, submit);
 	} else {
 		/* run the xor synchronously */
 		pr_debug("%s (sync): len: %zu\n", __func__, len);
+		WARN_ONCE(chan, "%s: no space for dma address conversion\n",
+			  __func__);
 
 		/* in the sync case the dest is an implied source
 		 * (assumes the dest is the first source)
 		 */
-		if (flags & ASYNC_TX_XOR_DROP_DST) {
+		if (submit->flags & ASYNC_TX_XOR_DROP_DST) {
 			src_cnt--;
 			src_list++;
 		}
 
 		/* wait for any prerequisite operations */
-		async_tx_quiesce(&depend_tx);
+		async_tx_quiesce(&submit->depend_tx);
 
-		do_sync_xor(dest, src_list, offset, src_cnt, len,
-			    flags, cb_fn, cb_param);
+		do_sync_xor(dest, src_list, offset, src_cnt, len, submit);
 
 		return NULL;
 	}
@@ -222,104 +229,90 @@ static int page_is_zero(struct page *p, unsigned int offset, size_t len)
 }
 
 /**
- * async_xor_zero_sum - attempt a xor parity check with a dma engine.
+ * async_xor_val - attempt a xor parity check with a dma engine.
  * @dest: destination page used if the xor is performed synchronously
- * @src_list: array of source pages.  The dest page must be listed as a source
- * 	at index zero.  The contents of this array may be overwritten.
+ * @src_list: array of source pages
  * @offset: offset in pages to start transaction
  * @src_cnt: number of source pages
  * @len: length in bytes
  * @result: 0 if sum == 0 else non-zero
- * @flags: ASYNC_TX_ACK, ASYNC_TX_DEP_ACK
- * @depend_tx: xor depends on the result of this transaction.
- * @cb_fn: function to call when the xor completes
- * @cb_param: parameter to pass to the callback routine
+ * @submit: submission / completion modifiers
+ *
+ * honored flags: ASYNC_TX_ACK
+ *
+ * src_list note: if the dest is also a source it must be at index zero.
+ * The contents of this array will be overwritten if a scribble region
+ * is not specified.
  */
 struct dma_async_tx_descriptor *
-async_xor_zero_sum(struct page *dest, struct page **src_list,
-	unsigned int offset, int src_cnt, size_t len,
-	u32 *result, enum async_tx_flags flags,
-	struct dma_async_tx_descriptor *depend_tx,
-	dma_async_tx_callback cb_fn, void *cb_param)
+async_xor_val(struct page *dest, struct page **src_list, unsigned int offset,
+	      int src_cnt, size_t len, enum sum_check_flags *result,
+	      struct async_submit_ctl *submit)
 {
-	struct dma_chan *chan = async_tx_find_channel(depend_tx, DMA_ZERO_SUM,
+	struct dma_chan *chan = async_tx_find_channel(submit, DMA_XOR_VAL,
 						      &dest, 1, src_list,
 						      src_cnt, len);
 	struct dma_device *device = chan ? chan->device : NULL;
 	struct dma_async_tx_descriptor *tx = NULL;
+	dma_addr_t *dma_src = NULL;
 
 	BUG_ON(src_cnt <= 1);
 
-	if (device && src_cnt <= device->max_xor) {
-		dma_addr_t *dma_src = (dma_addr_t *) src_list;
-		unsigned long dma_prep_flags = cb_fn ? DMA_PREP_INTERRUPT : 0;
+	if (submit->scribble)
+		dma_src = submit->scribble;
+	else if (sizeof(dma_addr_t) <= sizeof(struct page *))
+		dma_src = (dma_addr_t *) src_list;
+
+	if (dma_src && device && src_cnt <= device->max_xor) {
+		unsigned long dma_prep_flags;
 		int i;
 
 		pr_debug("%s: (async) len: %zu\n", __func__, len);
 
+		dma_prep_flags = submit->cb_fn ? DMA_PREP_INTERRUPT : 0;
 		for (i = 0; i < src_cnt; i++)
 			dma_src[i] = dma_map_page(device->dev, src_list[i],
 						  offset, len, DMA_TO_DEVICE);
 
-		tx = device->device_prep_dma_zero_sum(chan, dma_src, src_cnt,
-						      len, result,
-						      dma_prep_flags);
+		tx = device->device_prep_dma_xor_val(chan, dma_src, src_cnt,
+						     len, result,
+						     dma_prep_flags);
 		if (unlikely(!tx)) {
-			async_tx_quiesce(&depend_tx);
+			async_tx_quiesce(&submit->depend_tx);
 
 			while (!tx) {
 				dma_async_issue_pending(chan);
-				tx = device->device_prep_dma_zero_sum(chan,
+				tx = device->device_prep_dma_xor_val(chan,
 					dma_src, src_cnt, len, result,
 					dma_prep_flags);
 			}
 		}
 
-		async_tx_submit(chan, tx, flags, depend_tx, cb_fn, cb_param);
+		async_tx_submit(chan, tx, submit);
 	} else {
-		unsigned long xor_flags = flags;
+		enum async_tx_flags flags_orig = submit->flags;
 
 		pr_debug("%s: (sync) len: %zu\n", __func__, len);
+		WARN_ONCE(device && src_cnt <= device->max_xor,
+			  "%s: no space for dma address conversion\n",
+			  __func__);
 
-		xor_flags |= ASYNC_TX_XOR_DROP_DST;
-		xor_flags &= ~ASYNC_TX_ACK;
+		submit->flags |= ASYNC_TX_XOR_DROP_DST;
+		submit->flags &= ~ASYNC_TX_ACK;
 
-		tx = async_xor(dest, src_list, offset, src_cnt, len, xor_flags,
-			depend_tx, NULL, NULL);
+		tx = async_xor(dest, src_list, offset, src_cnt, len, submit);
 
 		async_tx_quiesce(&tx);
 
-		*result = page_is_zero(dest, offset, len) ? 0 : 1;
+		*result = !page_is_zero(dest, offset, len) << SUM_CHECK_P;
 
-		async_tx_sync_epilog(cb_fn, cb_param);
+		async_tx_sync_epilog(submit);
+		submit->flags = flags_orig;
 	}
 
 	return tx;
 }
-EXPORT_SYMBOL_GPL(async_xor_zero_sum);
-
-static int __init async_xor_init(void)
-{
-	#ifdef CONFIG_DMA_ENGINE
-	/* To conserve stack space the input src_list (array of page pointers)
-	 * is reused to hold the array of dma addresses passed to the driver.
-	 * This conversion is only possible when dma_addr_t is less than the
-	 * the size of a pointer.  HIGHMEM64G is known to violate this
-	 * assumption.
-	 */
-	BUILD_BUG_ON(sizeof(dma_addr_t) > sizeof(struct page *));
-	#endif
-
-	return 0;
-}
-
-static void __exit async_xor_exit(void)
-{
-	do { } while (0);
-}
-
-module_init(async_xor_init);
-module_exit(async_xor_exit);
+EXPORT_SYMBOL_GPL(async_xor_val);
 
 MODULE_AUTHOR("Intel Corporation");
 MODULE_DESCRIPTION("asynchronous xor/xor-zero-sum api");
diff --git a/crypto/async_tx/raid6test.c b/crypto/async_tx/raid6test.c
new file mode 100644
index 0000000..98c83ca
--- /dev/null
+++ b/crypto/async_tx/raid6test.c
@@ -0,0 +1,241 @@
+/*
+ * asynchronous raid6 recovery self test
+ * Copyright (c) 2009, Intel Corporation.
+ *
+ * based on drivers/md/raid6test/test.c:
+ * 	Copyright 2002-2007 H. Peter Anvin
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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/async_tx.h>
+#include <linux/random.h>
+
+#undef pr
+#define pr(fmt, args...) pr_info("raid6test: " fmt, ##args)
+
+#define NDISKS 16 /* Including P and Q */
+
+static struct page *dataptrs[NDISKS];
+static struct page *data[NDISKS+3];
+static struct page *spare;
+static struct page *recovi;
+static struct page *recovj;
+
+static void callback(void *param)
+{
+	struct completion *cmp = param;
+
+	complete(cmp);
+}
+
+static void makedata(int disks)
+{
+	int i, j;
+
+	for (i = 0; i < disks; i++) {
+		for (j = 0; j < PAGE_SIZE/sizeof(u32); j += sizeof(u32)) {
+			u32 *p = page_address(data[i]) + j;
+
+			*p = random32();
+		}
+
+		dataptrs[i] = data[i];
+	}
+}
+
+static char disk_type(int d, int disks)
+{
+	if (d == disks - 2)
+		return 'P';
+	else if (d == disks - 1)
+		return 'Q';
+	else
+		return 'D';
+}
+
+/* Recover two failed blocks. */
+static void raid6_dual_recov(int disks, size_t bytes, int faila, int failb, struct page **ptrs)
+{
+	struct async_submit_ctl submit;
+	addr_conv_t addr_conv[disks];
+	struct completion cmp;
+	struct dma_async_tx_descriptor *tx = NULL;
+	enum sum_check_flags result = ~0;
+
+	if (faila > failb)
+		swap(faila, failb);
+
+	if (failb == disks-1) {
+		if (faila == disks-2) {
+			/* P+Q failure.  Just rebuild the syndrome. */
+			init_async_submit(&submit, 0, NULL, NULL, NULL, addr_conv);
+			tx = async_gen_syndrome(ptrs, 0, disks, bytes, &submit);
+		} else {
+			struct page *blocks[disks];
+			struct page *dest;
+			int count = 0;
+			int i;
+
+			/* data+Q failure.  Reconstruct data from P,
+			 * then rebuild syndrome
+			 */
+			for (i = disks; i-- ; ) {
+				if (i == faila || i == failb)
+					continue;
+				blocks[count++] = ptrs[i];
+			}
+			dest = ptrs[faila];
+			init_async_submit(&submit, ASYNC_TX_XOR_ZERO_DST, NULL,
+					  NULL, NULL, addr_conv);
+			tx = async_xor(dest, blocks, 0, count, bytes, &submit);
+
+			init_async_submit(&submit, 0, tx, NULL, NULL, addr_conv);
+			tx = async_gen_syndrome(ptrs, 0, disks, bytes, &submit);
+		}
+	} else {
+		if (failb == disks-2) {
+			/* data+P failure. */
+			init_async_submit(&submit, 0, NULL, NULL, NULL, addr_conv);
+			tx = async_raid6_datap_recov(disks, bytes, faila, ptrs, &submit);
+		} else {
+			/* data+data failure. */
+			init_async_submit(&submit, 0, NULL, NULL, NULL, addr_conv);
+			tx = async_raid6_2data_recov(disks, bytes, faila, failb, ptrs, &submit);
+		}
+	}
+	init_completion(&cmp);
+	init_async_submit(&submit, ASYNC_TX_ACK, tx, callback, &cmp, addr_conv);
+	tx = async_syndrome_val(ptrs, 0, disks, bytes, &result, spare, &submit);
+	async_tx_issue_pending(tx);
+
+	if (wait_for_completion_timeout(&cmp, msecs_to_jiffies(3000)) == 0)
+		pr("%s: timeout! (faila: %d failb: %d disks: %d)\n",
+		   __func__, faila, failb, disks);
+
+	if (result != 0)
+		pr("%s: validation failure! faila: %d failb: %d sum_check_flags: %x\n",
+		   __func__, faila, failb, result);
+}
+
+static int test_disks(int i, int j, int disks)
+{
+	int erra, errb;
+
+	memset(page_address(recovi), 0xf0, PAGE_SIZE);
+	memset(page_address(recovj), 0xba, PAGE_SIZE);
+
+	dataptrs[i] = recovi;
+	dataptrs[j] = recovj;
+
+	raid6_dual_recov(disks, PAGE_SIZE, i, j, dataptrs);
+
+	erra = memcmp(page_address(data[i]), page_address(recovi), PAGE_SIZE);
+	errb = memcmp(page_address(data[j]), page_address(recovj), PAGE_SIZE);
+
+	pr("%s(%d, %d): faila=%3d(%c)  failb=%3d(%c)  %s\n",
+	   __func__, i, j, i, disk_type(i, disks), j, disk_type(j, disks),
+	   (!erra && !errb) ? "OK" : !erra ? "ERRB" : !errb ? "ERRA" : "ERRAB");
+
+	dataptrs[i] = data[i];
+	dataptrs[j] = data[j];
+
+	return erra || errb;
+}
+
+static int test(int disks, int *tests)
+{
+	addr_conv_t addr_conv[disks];
+	struct dma_async_tx_descriptor *tx;
+	struct async_submit_ctl submit;
+	struct completion cmp;
+	int err = 0;
+	int i, j;
+
+	recovi = data[disks];
+	recovj = data[disks+1];
+	spare  = data[disks+2];
+
+	makedata(disks);
+
+	/* Nuke syndromes */
+	memset(page_address(data[disks-2]), 0xee, PAGE_SIZE);
+	memset(page_address(data[disks-1]), 0xee, PAGE_SIZE);
+
+	/* Generate assumed good syndrome */
+	init_completion(&cmp);
+	init_async_submit(&submit, ASYNC_TX_ACK, NULL, callback, &cmp, addr_conv);
+	tx = async_gen_syndrome(dataptrs, 0, disks, PAGE_SIZE, &submit);
+	async_tx_issue_pending(tx);
+
+	if (wait_for_completion_timeout(&cmp, msecs_to_jiffies(3000)) == 0) {
+		pr("error: initial gen_syndrome(%d) timed out\n", disks);
+		return 1;
+	}
+
+	pr("testing the %d-disk case...\n", disks);
+	for (i = 0; i < disks-1; i++)
+		for (j = i+1; j < disks; j++) {
+			(*tests)++;
+			err += test_disks(i, j, disks);
+		}
+
+	return err;
+}
+
+
+static int raid6_test(void)
+{
+	int err = 0;
+	int tests = 0;
+	int i;
+
+	for (i = 0; i < NDISKS+3; i++) {
+		data[i] = alloc_page(GFP_KERNEL);
+		if (!data[i]) {
+			while (i--)
+				put_page(data[i]);
+			return -ENOMEM;
+		}
+	}
+
+	/* the 4-disk and 5-disk cases are special for the recovery code */
+	if (NDISKS > 4)
+		err += test(4, &tests);
+	if (NDISKS > 5)
+		err += test(5, &tests);
+	err += test(NDISKS, &tests);
+
+	pr("\n");
+	pr("complete (%d tests, %d failure%s)\n",
+	   tests, err, err == 1 ? "" : "s");
+
+	for (i = 0; i < NDISKS+3; i++)
+		put_page(data[i]);
+
+	return 0;
+}
+
+static void raid6_test_exit(void)
+{
+}
+
+/* when compiled-in wait for drivers to load first (assumes dma drivers
+ * are also compliled-in)
+ */
+late_initcall(raid6_test);
+module_exit(raid6_test_exit);
+MODULE_AUTHOR("Dan Williams <dan.j.williams@intel.com>");
+MODULE_DESCRIPTION("asynchronous RAID-6 recovery self tests");
+MODULE_LICENSE("GPL");
diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index 3b3c01b..912a51b 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -4,7 +4,7 @@
 
 menuconfig DMADEVICES
 	bool "DMA Engine support"
-	depends on !HIGHMEM64G && HAS_DMA
+	depends on HAS_DMA
 	help
 	  DMA engines can do asynchronous data transfers without
 	  involving the host CPU.  Currently, this framework can be
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 5a87384..9659847 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -644,8 +644,12 @@ int dma_async_device_register(struct dma_device *device)
 		!device->device_prep_dma_memcpy);
 	BUG_ON(dma_has_cap(DMA_XOR, device->cap_mask) &&
 		!device->device_prep_dma_xor);
-	BUG_ON(dma_has_cap(DMA_ZERO_SUM, device->cap_mask) &&
-		!device->device_prep_dma_zero_sum);
+	BUG_ON(dma_has_cap(DMA_XOR_VAL, device->cap_mask) &&
+		!device->device_prep_dma_xor_val);
+	BUG_ON(dma_has_cap(DMA_PQ, device->cap_mask) &&
+		!device->device_prep_dma_pq);
+	BUG_ON(dma_has_cap(DMA_PQ_VAL, device->cap_mask) &&
+		!device->device_prep_dma_pq_val);
 	BUG_ON(dma_has_cap(DMA_MEMSET, device->cap_mask) &&
 		!device->device_prep_dma_memset);
 	BUG_ON(dma_has_cap(DMA_INTERRUPT, device->cap_mask) &&
@@ -939,49 +943,24 @@ EXPORT_SYMBOL(dma_async_tx_descriptor_init);
 
 /* dma_wait_for_async_tx - spin wait for a transaction to complete
  * @tx: in-flight transaction to wait on
- *
- * This routine assumes that tx was obtained from a call to async_memcpy,
- * async_xor, async_memset, etc which ensures that tx is "in-flight" (prepped
- * and submitted).  Walking the parent chain is only meant to cover for DMA
- * drivers that do not implement the DMA_INTERRUPT capability and may race with
- * the driver's descriptor cleanup routine.
  */
 enum dma_status
 dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx)
 {
-	enum dma_status status;
-	struct dma_async_tx_descriptor *iter;
-	struct dma_async_tx_descriptor *parent;
+	unsigned long dma_sync_wait_timeout = jiffies + msecs_to_jiffies(5000);
 
 	if (!tx)
 		return DMA_SUCCESS;
 
-	WARN_ONCE(tx->parent, "%s: speculatively walking dependency chain for"
-		  " %s\n", __func__, dma_chan_name(tx->chan));
-
-	/* poll through the dependency chain, return when tx is complete */
-	do {
-		iter = tx;
-
-		/* find the root of the unsubmitted dependency chain */
-		do {
-			parent = iter->parent;
-			if (!parent)
-				break;
-			else
-				iter = parent;
-		} while (parent);
-
-		/* there is a small window for ->parent == NULL and
-		 * ->cookie == -EBUSY
-		 */
-		while (iter->cookie == -EBUSY)
-			cpu_relax();
-
-		status = dma_sync_wait(iter->chan, iter->cookie);
-	} while (status == DMA_IN_PROGRESS || (iter != tx));
-
-	return status;
+	while (tx->cookie == -EBUSY) {
+		if (time_after_eq(jiffies, dma_sync_wait_timeout)) {
+			pr_err("%s timeout waiting for descriptor submission\n",
+				__func__);
+			return DMA_ERROR;
+		}
+		cpu_relax();
+	}
+	return dma_sync_wait(tx->chan, tx->cookie);
 }
 EXPORT_SYMBOL_GPL(dma_wait_for_async_tx);
 
diff --git a/drivers/dma/dmatest.c b/drivers/dma/dmatest.c
index fb7da51..58e49e4 100644
--- a/drivers/dma/dmatest.c
+++ b/drivers/dma/dmatest.c
@@ -43,6 +43,11 @@ module_param(xor_sources, uint, S_IRUGO);
 MODULE_PARM_DESC(xor_sources,
 		"Number of xor source buffers (default: 3)");
 
+static unsigned int pq_sources = 3;
+module_param(pq_sources, uint, S_IRUGO);
+MODULE_PARM_DESC(pq_sources,
+		"Number of p+q source buffers (default: 3)");
+
 /*
  * Initialization patterns. All bytes in the source buffer has bit 7
  * set, all bytes in the destination buffer has bit 7 cleared.
@@ -227,6 +232,7 @@ static int dmatest_func(void *data)
 	dma_cookie_t		cookie;
 	enum dma_status		status;
 	enum dma_ctrl_flags 	flags;
+	u8			pq_coefs[pq_sources];
 	int			ret;
 	int			src_cnt;
 	int			dst_cnt;
@@ -243,6 +249,11 @@ static int dmatest_func(void *data)
 	else if (thread->type == DMA_XOR) {
 		src_cnt = xor_sources | 1; /* force odd to ensure dst = src */
 		dst_cnt = 1;
+	} else if (thread->type == DMA_PQ) {
+		src_cnt = pq_sources | 1; /* force odd to ensure dst = src */
+		dst_cnt = 2;
+		for (i = 0; i < pq_sources; i++)
+			pq_coefs[i] = 1;
 	} else
 		goto err_srcs;
 
@@ -310,6 +321,15 @@ static int dmatest_func(void *data)
 						      dma_dsts[0] + dst_off,
 						      dma_srcs, xor_sources,
 						      len, flags);
+		else if (thread->type == DMA_PQ) {
+			dma_addr_t dma_pq[dst_cnt];
+
+			for (i = 0; i < dst_cnt; i++)
+				dma_pq[i] = dma_dsts[i] + dst_off;
+			tx = dev->device_prep_dma_pq(chan, dma_pq, dma_srcs,
+						     pq_sources, pq_coefs,
+						     len, flags);
+		}
 
 		if (!tx) {
 			for (i = 0; i < src_cnt; i++)
@@ -446,6 +466,8 @@ static int dmatest_add_threads(struct dmatest_chan *dtc, enum dma_transaction_ty
 		op = "copy";
 	else if (type == DMA_XOR)
 		op = "xor";
+	else if (type == DMA_PQ)
+		op = "pq";
 	else
 		return -EINVAL;
 
@@ -501,6 +523,10 @@ static int dmatest_add_channel(struct dma_chan *chan)
 		cnt = dmatest_add_threads(dtc, DMA_XOR);
 		thread_count += cnt > 0 ?: 0;
 	}
+	if (dma_has_cap(DMA_PQ, dma_dev->cap_mask)) {
+		cnt = dmatest_add_threads(dtc, DMA_PQ);
+		thread_count += cnt > 0 ?: 0;
+	}
 
 	pr_info("dmatest: Started %u threads using %s\n",
 		thread_count, dma_chan_name(chan));
diff --git a/drivers/dma/iop-adma.c b/drivers/dma/iop-adma.c
index 2f05226..4496bc6 100644
--- a/drivers/dma/iop-adma.c
+++ b/drivers/dma/iop-adma.c
@@ -660,9 +660,9 @@ iop_adma_prep_dma_xor(struct dma_chan *chan, dma_addr_t dma_dest,
 }
 
 static struct dma_async_tx_descriptor *
-iop_adma_prep_dma_zero_sum(struct dma_chan *chan, dma_addr_t *dma_src,
-			   unsigned int src_cnt, size_t len, u32 *result,
-			   unsigned long flags)
+iop_adma_prep_dma_xor_val(struct dma_chan *chan, dma_addr_t *dma_src,
+			  unsigned int src_cnt, size_t len, u32 *result,
+			  unsigned long flags)
 {
 	struct iop_adma_chan *iop_chan = to_iop_adma_chan(chan);
 	struct iop_adma_desc_slot *sw_desc, *grp_start;
@@ -906,7 +906,7 @@ out:
 
 #define IOP_ADMA_NUM_SRC_TEST 4 /* must be <= 15 */
 static int __devinit
-iop_adma_xor_zero_sum_self_test(struct iop_adma_device *device)
+iop_adma_xor_val_self_test(struct iop_adma_device *device)
 {
 	int i, src_idx;
 	struct page *dest;
@@ -1002,7 +1002,7 @@ iop_adma_xor_zero_sum_self_test(struct iop_adma_device *device)
 		PAGE_SIZE, DMA_TO_DEVICE);
 
 	/* skip zero sum if the capability is not present */
-	if (!dma_has_cap(DMA_ZERO_SUM, dma_chan->device->cap_mask))
+	if (!dma_has_cap(DMA_XOR_VAL, dma_chan->device->cap_mask))
 		goto free_resources;
 
 	/* zero sum the sources with the destintation page */
@@ -1016,10 +1016,10 @@ iop_adma_xor_zero_sum_self_test(struct iop_adma_device *device)
 		dma_srcs[i] = dma_map_page(dma_chan->device->dev,
 					   zero_sum_srcs[i], 0, PAGE_SIZE,
 					   DMA_TO_DEVICE);
-	tx = iop_adma_prep_dma_zero_sum(dma_chan, dma_srcs,
-					IOP_ADMA_NUM_SRC_TEST + 1, PAGE_SIZE,
-					&zero_sum_result,
-					DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+	tx = iop_adma_prep_dma_xor_val(dma_chan, dma_srcs,
+				       IOP_ADMA_NUM_SRC_TEST + 1, PAGE_SIZE,
+				       &zero_sum_result,
+				       DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 
 	cookie = iop_adma_tx_submit(tx);
 	iop_adma_issue_pending(dma_chan);
@@ -1072,10 +1072,10 @@ iop_adma_xor_zero_sum_self_test(struct iop_adma_device *device)
 		dma_srcs[i] = dma_map_page(dma_chan->device->dev,
 					   zero_sum_srcs[i], 0, PAGE_SIZE,
 					   DMA_TO_DEVICE);
-	tx = iop_adma_prep_dma_zero_sum(dma_chan, dma_srcs,
-					IOP_ADMA_NUM_SRC_TEST + 1, PAGE_SIZE,
-					&zero_sum_result,
-					DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+	tx = iop_adma_prep_dma_xor_val(dma_chan, dma_srcs,
+				       IOP_ADMA_NUM_SRC_TEST + 1, PAGE_SIZE,
+				       &zero_sum_result,
+				       DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 
 	cookie = iop_adma_tx_submit(tx);
 	iop_adma_issue_pending(dma_chan);
@@ -1192,9 +1192,9 @@ static int __devinit iop_adma_probe(struct platform_device *pdev)
 		dma_dev->max_xor = iop_adma_get_max_xor();
 		dma_dev->device_prep_dma_xor = iop_adma_prep_dma_xor;
 	}
-	if (dma_has_cap(DMA_ZERO_SUM, dma_dev->cap_mask))
-		dma_dev->device_prep_dma_zero_sum =
-			iop_adma_prep_dma_zero_sum;
+	if (dma_has_cap(DMA_XOR_VAL, dma_dev->cap_mask))
+		dma_dev->device_prep_dma_xor_val =
+			iop_adma_prep_dma_xor_val;
 	if (dma_has_cap(DMA_INTERRUPT, dma_dev->cap_mask))
 		dma_dev->device_prep_dma_interrupt =
 			iop_adma_prep_dma_interrupt;
@@ -1249,7 +1249,7 @@ static int __devinit iop_adma_probe(struct platform_device *pdev)
 
 	if (dma_has_cap(DMA_XOR, dma_dev->cap_mask) ||
 		dma_has_cap(DMA_MEMSET, dma_dev->cap_mask)) {
-		ret = iop_adma_xor_zero_sum_self_test(adev);
+		ret = iop_adma_xor_val_self_test(adev);
 		dev_dbg(&pdev->dev, "xor self test returned %d\n", ret);
 		if (ret)
 			goto err_free_iop_chan;
@@ -1257,12 +1257,12 @@ static int __devinit iop_adma_probe(struct platform_device *pdev)
 
 	dev_printk(KERN_INFO, &pdev->dev, "Intel(R) IOP: "
 	  "( %s%s%s%s%s%s%s%s%s%s)\n",
-	  dma_has_cap(DMA_PQ_XOR, dma_dev->cap_mask) ? "pq_xor " : "",
+	  dma_has_cap(DMA_PQ, dma_dev->cap_mask) ? "pq " : "",
 	  dma_has_cap(DMA_PQ_UPDATE, dma_dev->cap_mask) ? "pq_update " : "",
-	  dma_has_cap(DMA_PQ_ZERO_SUM, dma_dev->cap_mask) ? "pq_zero_sum " : "",
+	  dma_has_cap(DMA_PQ_VAL, dma_dev->cap_mask) ? "pq_val " : "",
 	  dma_has_cap(DMA_XOR, dma_dev->cap_mask) ? "xor " : "",
 	  dma_has_cap(DMA_DUAL_XOR, dma_dev->cap_mask) ? "dual_xor " : "",
-	  dma_has_cap(DMA_ZERO_SUM, dma_dev->cap_mask) ? "xor_zero_sum " : "",
+	  dma_has_cap(DMA_XOR_VAL, dma_dev->cap_mask) ? "xor_val " : "",
 	  dma_has_cap(DMA_MEMSET, dma_dev->cap_mask)  ? "fill " : "",
 	  dma_has_cap(DMA_MEMCPY_CRC32C, dma_dev->cap_mask) ? "cpy+crc " : "",
 	  dma_has_cap(DMA_MEMCPY, dma_dev->cap_mask) ? "cpy " : "",
diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index 36e0675..09c0c6e 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -124,6 +124,8 @@ config MD_RAID456
 	select MD_RAID6_PQ
 	select ASYNC_MEMCPY
 	select ASYNC_XOR
+	select ASYNC_PQ
+	select ASYNC_RAID6_RECOV
 	---help---
 	  A RAID-5 set of N drives with a capacity of C MB per drive provides
 	  the capacity of C * (N - 1) MB, and protects against a failure
@@ -152,9 +154,33 @@ config MD_RAID456
 
 	  If unsure, say Y.
 
+config MULTICORE_RAID456
+	bool "RAID-4/RAID-5/RAID-6 Multicore processing (EXPERIMENTAL)"
+	depends on MD_RAID456
+	depends on SMP
+	depends on EXPERIMENTAL
+	---help---
+	  Enable the raid456 module to dispatch per-stripe raid operations to a
+	  thread pool.
+
+	  If unsure, say N.
+
 config MD_RAID6_PQ
 	tristate
 
+config ASYNC_RAID6_TEST
+	tristate "Self test for hardware accelerated raid6 recovery"
+	depends on MD_RAID6_PQ
+	select ASYNC_RAID6_RECOV
+	---help---
+	  This is a one-shot self test that permutes through the
+	  recovery of all the possible two disk failure scenarios for a
+	  N-disk array.  Recovery is performed with the asynchronous
+	  raid6 recovery routines, and will optionally use an offload
+	  engine if one is available.
+
+	  If unsure, say N.
+
 config MD_MULTIPATH
 	tristate "Multipath I/O support"
 	depends on BLK_DEV_MD
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index bb37fb1..0a5cf21 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -47,7 +47,9 @@
 #include <linux/kthread.h>
 #include <linux/raid/pq.h>
 #include <linux/async_tx.h>
+#include <linux/async.h>
 #include <linux/seq_file.h>
+#include <linux/cpu.h>
 #include "md.h"
 #include "raid5.h"
 #include "bitmap.h"
@@ -499,11 +501,14 @@ async_copy_data(int frombio, struct bio *bio, struct page *page,
 	struct page *bio_page;
 	int i;
 	int page_offset;
+	struct async_submit_ctl submit;
 
 	if (bio->bi_sector >= sector)
 		page_offset = (signed)(bio->bi_sector - sector) * 512;
 	else
 		page_offset = (signed)(sector - bio->bi_sector) * -512;
+
+	init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
 	bio_for_each_segment(bvl, bio, i) {
 		int len = bio_iovec_idx(bio, i)->bv_len;
 		int clen;
@@ -525,15 +530,14 @@ async_copy_data(int frombio, struct bio *bio, struct page *page,
 			bio_page = bio_iovec_idx(bio, i)->bv_page;
 			if (frombio)
 				tx = async_memcpy(page, bio_page, page_offset,
-					b_offset, clen,
-					ASYNC_TX_DEP_ACK,
-					tx, NULL, NULL);
+						  b_offset, clen, &submit);
 			else
 				tx = async_memcpy(bio_page, page, b_offset,
-					page_offset, clen,
-					ASYNC_TX_DEP_ACK,
-					tx, NULL, NULL);
+						  page_offset, clen, &submit);
 		}
+		/* chain the operations */
+		submit.depend_tx = tx;
+
 		if (clen < len) /* hit end of page */
 			break;
 		page_offset +=  len;
@@ -592,6 +596,7 @@ static void ops_run_biofill(struct stripe_head *sh)
 {
 	struct dma_async_tx_descriptor *tx = NULL;
 	raid5_conf_t *conf = sh->raid_conf;
+	struct async_submit_ctl submit;
 	int i;
 
 	pr_debug("%s: stripe %llu\n", __func__,
@@ -615,22 +620,34 @@ static void ops_run_biofill(struct stripe_head *sh)
 	}
 
 	atomic_inc(&sh->count);
-	async_trigger_callback(ASYNC_TX_DEP_ACK | ASYNC_TX_ACK, tx,
-		ops_complete_biofill, sh);
+	init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_biofill, sh, NULL);
+	async_trigger_callback(&submit);
 }
 
-static void ops_complete_compute5(void *stripe_head_ref)
+static void mark_target_uptodate(struct stripe_head *sh, int target)
 {
-	struct stripe_head *sh = stripe_head_ref;
-	int target = sh->ops.target;
-	struct r5dev *tgt = &sh->dev[target];
+	struct r5dev *tgt;
 
-	pr_debug("%s: stripe %llu\n", __func__,
-		(unsigned long long)sh->sector);
+	if (target < 0)
+		return;
 
+	tgt = &sh->dev[target];
 	set_bit(R5_UPTODATE, &tgt->flags);
 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
 	clear_bit(R5_Wantcompute, &tgt->flags);
+}
+
+static void ops_complete_compute(void *stripe_head_ref)
+{
+	struct stripe_head *sh = stripe_head_ref;
+
+	pr_debug("%s: stripe %llu\n", __func__,
+		(unsigned long long)sh->sector);
+
+	/* mark the computed target(s) as uptodate */
+	mark_target_uptodate(sh, sh->ops.target);
+	mark_target_uptodate(sh, sh->ops.target2);
+
 	clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
 	if (sh->check_state == check_state_compute_run)
 		sh->check_state = check_state_compute_result;
@@ -638,16 +655,24 @@ static void ops_complete_compute5(void *stripe_head_ref)
 	release_stripe(sh);
 }
 
-static struct dma_async_tx_descriptor *ops_run_compute5(struct stripe_head *sh)
+/* return a pointer to the address conversion region of the scribble buffer */
+static addr_conv_t *to_addr_conv(struct stripe_head *sh,
+				 struct raid5_percpu *percpu)
+{
+	return percpu->scribble + sizeof(struct page *) * (sh->disks + 2);
+}
+
+static struct dma_async_tx_descriptor *
+ops_run_compute5(struct stripe_head *sh, struct raid5_percpu *percpu)
 {
-	/* kernel stack size limits the total number of disks */
 	int disks = sh->disks;
-	struct page *xor_srcs[disks];
+	struct page **xor_srcs = percpu->scribble;
 	int target = sh->ops.target;
 	struct r5dev *tgt = &sh->dev[target];
 	struct page *xor_dest = tgt->page;
 	int count = 0;
 	struct dma_async_tx_descriptor *tx;
+	struct async_submit_ctl submit;
 	int i;
 
 	pr_debug("%s: stripe %llu block: %d\n",
@@ -660,17 +685,207 @@ static struct dma_async_tx_descriptor *ops_run_compute5(struct stripe_head *sh)
 
 	atomic_inc(&sh->count);
 
+	init_async_submit(&submit, ASYNC_TX_XOR_ZERO_DST, NULL,
+			  ops_complete_compute, sh, to_addr_conv(sh, percpu));
 	if (unlikely(count == 1))
-		tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE,
-			0, NULL, ops_complete_compute5, sh);
+		tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
 	else
-		tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
-			ASYNC_TX_XOR_ZERO_DST, NULL,
-			ops_complete_compute5, sh);
+		tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
 
 	return tx;
 }
 
+/* set_syndrome_sources - populate source buffers for gen_syndrome
+ * @srcs - (struct page *) array of size sh->disks
+ * @sh - stripe_head to parse
+ *
+ * Populates srcs in proper layout order for the stripe and returns the
+ * 'count' of sources to be used in a call to async_gen_syndrome.  The P
+ * destination buffer is recorded in srcs[count] and the Q destination
+ * is recorded in srcs[count+1]].
+ */
+static int set_syndrome_sources(struct page **srcs, struct stripe_head *sh)
+{
+	int disks = sh->disks;
+	int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
+	int d0_idx = raid6_d0(sh);
+	int count;
+	int i;
+
+	for (i = 0; i < disks; i++)
+		srcs[i] = (void *)raid6_empty_zero_page;
+
+	count = 0;
+	i = d0_idx;
+	do {
+		int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
+
+		srcs[slot] = sh->dev[i].page;
+		i = raid6_next_disk(i, disks);
+	} while (i != d0_idx);
+	BUG_ON(count != syndrome_disks);
+
+	return count;
+}
+
+static struct dma_async_tx_descriptor *
+ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
+{
+	int disks = sh->disks;
+	struct page **blocks = percpu->scribble;
+	int target;
+	int qd_idx = sh->qd_idx;
+	struct dma_async_tx_descriptor *tx;
+	struct async_submit_ctl submit;
+	struct r5dev *tgt;
+	struct page *dest;
+	int i;
+	int count;
+
+	if (sh->ops.target < 0)
+		target = sh->ops.target2;
+	else if (sh->ops.target2 < 0)
+		target = sh->ops.target;
+	else
+		/* we should only have one valid target */
+		BUG();
+	BUG_ON(target < 0);
+	pr_debug("%s: stripe %llu block: %d\n",
+		__func__, (unsigned long long)sh->sector, target);
+
+	tgt = &sh->dev[target];
+	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
+	dest = tgt->page;
+
+	atomic_inc(&sh->count);
+
+	if (target == qd_idx) {
+		count = set_syndrome_sources(blocks, sh);
+		blocks[count] = NULL; /* regenerating p is not necessary */
+		BUG_ON(blocks[count+1] != dest); /* q should already be set */
+		init_async_submit(&submit, 0, NULL, ops_complete_compute, sh,
+				  to_addr_conv(sh, percpu));
+		tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE, &submit);
+	} else {
+		/* Compute any data- or p-drive using XOR */
+		count = 0;
+		for (i = disks; i-- ; ) {
+			if (i == target || i == qd_idx)
+				continue;
+			blocks[count++] = sh->dev[i].page;
+		}
+
+		init_async_submit(&submit, ASYNC_TX_XOR_ZERO_DST, NULL,
+				  ops_complete_compute, sh,
+				  to_addr_conv(sh, percpu));
+		tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE, &submit);
+	}
+
+	return tx;
+}
+
+static struct dma_async_tx_descriptor *
+ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
+{
+	int i, count, disks = sh->disks;
+	int syndrome_disks = sh->ddf_layout ? disks : disks-2;
+	int d0_idx = raid6_d0(sh);
+	int faila = -1, failb = -1;
+	int target = sh->ops.target;
+	int target2 = sh->ops.target2;
+	struct r5dev *tgt = &sh->dev[target];
+	struct r5dev *tgt2 = &sh->dev[target2];
+	struct dma_async_tx_descriptor *tx;
+	struct page **blocks = percpu->scribble;
+	struct async_submit_ctl submit;
+
+	pr_debug("%s: stripe %llu block1: %d block2: %d\n",
+		 __func__, (unsigned long long)sh->sector, target, target2);
+	BUG_ON(target < 0 || target2 < 0);
+	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
+	BUG_ON(!test_bit(R5_Wantcompute, &tgt2->flags));
+
+	/* we need to open-code set_syndrome_sources to handle to the
+	 * slot number conversion for 'faila' and 'failb'
+	 */
+	for (i = 0; i < disks ; i++)
+		blocks[i] = (void *)raid6_empty_zero_page;
+	count = 0;
+	i = d0_idx;
+	do {
+		int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
+
+		blocks[slot] = sh->dev[i].page;
+
+		if (i == target)
+			faila = slot;
+		if (i == target2)
+			failb = slot;
+		i = raid6_next_disk(i, disks);
+	} while (i != d0_idx);
+	BUG_ON(count != syndrome_disks);
+
+	BUG_ON(faila == failb);
+	if (failb < faila)
+		swap(faila, failb);
+	pr_debug("%s: stripe: %llu faila: %d failb: %d\n",
+		 __func__, (unsigned long long)sh->sector, faila, failb);
+
+	atomic_inc(&sh->count);
+
+	if (failb == syndrome_disks+1) {
+		/* Q disk is one of the missing disks */
+		if (faila == syndrome_disks) {
+			/* Missing P+Q, just recompute */
+			init_async_submit(&submit, 0, NULL, ops_complete_compute,
+					  sh, to_addr_conv(sh, percpu));
+			return async_gen_syndrome(blocks, 0, count+2,
+						  STRIPE_SIZE, &submit);
+		} else {
+			struct page *dest;
+			int data_target;
+			int qd_idx = sh->qd_idx;
+
+			/* Missing D+Q: recompute D from P, then recompute Q */
+			if (target == qd_idx)
+				data_target = target2;
+			else
+				data_target = target;
+
+			count = 0;
+			for (i = disks; i-- ; ) {
+				if (i == data_target || i == qd_idx)
+					continue;
+				blocks[count++] = sh->dev[i].page;
+			}
+			dest = sh->dev[data_target].page;
+			init_async_submit(&submit, ASYNC_TX_XOR_ZERO_DST, NULL,
+					  NULL, NULL, to_addr_conv(sh, percpu));
+			tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE,
+				       &submit);
+
+			count = set_syndrome_sources(blocks, sh);
+			init_async_submit(&submit, 0, tx, ops_complete_compute,
+					  sh, to_addr_conv(sh, percpu));
+			return async_gen_syndrome(blocks, 0, count+2,
+						  STRIPE_SIZE, &submit);
+		}
+	}
+
+	init_async_submit(&submit, 0, NULL, ops_complete_compute, sh,
+			  to_addr_conv(sh, percpu));
+	if (failb == syndrome_disks) {
+		/* We're missing D+P. */
+		return async_raid6_datap_recov(syndrome_disks+2, STRIPE_SIZE,
+					       faila, blocks, &submit);
+	} else {
+		/* We're missing D+D. */
+		return async_raid6_2data_recov(syndrome_disks+2, STRIPE_SIZE,
+					       faila, failb, blocks, &submit);
+	}
+}
+
+
 static void ops_complete_prexor(void *stripe_head_ref)
 {
 	struct stripe_head *sh = stripe_head_ref;
@@ -680,12 +895,13 @@ static void ops_complete_prexor(void *stripe_head_ref)
 }
 
 static struct dma_async_tx_descriptor *
-ops_run_prexor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
+ops_run_prexor(struct stripe_head *sh, struct raid5_percpu *percpu,
+	       struct dma_async_tx_descriptor *tx)
 {
-	/* kernel stack size limits the total number of disks */
 	int disks = sh->disks;
-	struct page *xor_srcs[disks];
+	struct page **xor_srcs = percpu->scribble;
 	int count = 0, pd_idx = sh->pd_idx, i;
+	struct async_submit_ctl submit;
 
 	/* existing parity data subtracted */
 	struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
@@ -700,9 +916,9 @@ ops_run_prexor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
 			xor_srcs[count++] = dev->page;
 	}
 
-	tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
-		ASYNC_TX_DEP_ACK | ASYNC_TX_XOR_DROP_DST, tx,
-		ops_complete_prexor, sh);
+	init_async_submit(&submit, ASYNC_TX_XOR_DROP_DST, tx,
+			  ops_complete_prexor, sh, to_addr_conv(sh, percpu));
+	tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
 
 	return tx;
 }
@@ -742,17 +958,21 @@ ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
 	return tx;
 }
 
-static void ops_complete_postxor(void *stripe_head_ref)
+static void ops_complete_reconstruct(void *stripe_head_ref)
 {
 	struct stripe_head *sh = stripe_head_ref;
-	int disks = sh->disks, i, pd_idx = sh->pd_idx;
+	int disks = sh->disks;
+	int pd_idx = sh->pd_idx;
+	int qd_idx = sh->qd_idx;
+	int i;
 
 	pr_debug("%s: stripe %llu\n", __func__,
 		(unsigned long long)sh->sector);
 
 	for (i = disks; i--; ) {
 		struct r5dev *dev = &sh->dev[i];
-		if (dev->written || i == pd_idx)
+
+		if (dev->written || i == pd_idx || i == qd_idx)
 			set_bit(R5_UPTODATE, &dev->flags);
 	}
 
@@ -770,12 +990,12 @@ static void ops_complete_postxor(void *stripe_head_ref)
 }
 
 static void
-ops_run_postxor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
+ops_run_reconstruct5(struct stripe_head *sh, struct raid5_percpu *percpu,
+		     struct dma_async_tx_descriptor *tx)
 {
-	/* kernel stack size limits the total number of disks */
 	int disks = sh->disks;
-	struct page *xor_srcs[disks];
-
+	struct page **xor_srcs = percpu->scribble;
+	struct async_submit_ctl submit;
 	int count = 0, pd_idx = sh->pd_idx, i;
 	struct page *xor_dest;
 	int prexor = 0;
@@ -809,18 +1029,36 @@ ops_run_postxor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
 	 * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
 	 * for the synchronous xor case
 	 */
-	flags = ASYNC_TX_DEP_ACK | ASYNC_TX_ACK |
+	flags = ASYNC_TX_ACK |
 		(prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
 
 	atomic_inc(&sh->count);
 
-	if (unlikely(count == 1)) {
-		flags &= ~(ASYNC_TX_XOR_DROP_DST | ASYNC_TX_XOR_ZERO_DST);
-		tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE,
-			flags, tx, ops_complete_postxor, sh);
-	} else
-		tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
-			flags, tx, ops_complete_postxor, sh);
+	init_async_submit(&submit, flags, tx, ops_complete_reconstruct, sh,
+			  to_addr_conv(sh, percpu));
+	if (unlikely(count == 1))
+		tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
+	else
+		tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
+}
+
+static void
+ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
+		     struct dma_async_tx_descriptor *tx)
+{
+	struct async_submit_ctl submit;
+	struct page **blocks = percpu->scribble;
+	int count;
+
+	pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
+
+	count = set_syndrome_sources(blocks, sh);
+
+	atomic_inc(&sh->count);
+
+	init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_reconstruct,
+			  sh, to_addr_conv(sh, percpu));
+	async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
 }
 
 static void ops_complete_check(void *stripe_head_ref)
@@ -835,63 +1073,115 @@ static void ops_complete_check(void *stripe_head_ref)
 	release_stripe(sh);
 }
 
-static void ops_run_check(struct stripe_head *sh)
+static void ops_run_check_p(struct stripe_head *sh, struct raid5_percpu *percpu)
 {
-	/* kernel stack size limits the total number of disks */
 	int disks = sh->disks;
-	struct page *xor_srcs[disks];
+	int pd_idx = sh->pd_idx;
+	int qd_idx = sh->qd_idx;
+	struct page *xor_dest;
+	struct page **xor_srcs = percpu->scribble;
 	struct dma_async_tx_descriptor *tx;
-
-	int count = 0, pd_idx = sh->pd_idx, i;
-	struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
+	struct async_submit_ctl submit;
+	int count;
+	int i;
 
 	pr_debug("%s: stripe %llu\n", __func__,
 		(unsigned long long)sh->sector);
 
+	count = 0;
+	xor_dest = sh->dev[pd_idx].page;
+	xor_srcs[count++] = xor_dest;
 	for (i = disks; i--; ) {
-		struct r5dev *dev = &sh->dev[i];
-		if (i != pd_idx)
-			xor_srcs[count++] = dev->page;
+		if (i == pd_idx || i == qd_idx)
+			continue;
+		xor_srcs[count++] = sh->dev[i].page;
 	}
 
-	tx = async_xor_zero_sum(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
-		&sh->ops.zero_sum_result, 0, NULL, NULL, NULL);
+	init_async_submit(&submit, 0, NULL, NULL, NULL,
+			  to_addr_conv(sh, percpu));
+	tx = async_xor_val(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
+			   &sh->ops.zero_sum_result, &submit);
+
+	atomic_inc(&sh->count);
+	init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_check, sh, NULL);
+	tx = async_trigger_callback(&submit);
+}
+
+static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu, int checkp)
+{
+	struct page **srcs = percpu->scribble;
+	struct async_submit_ctl submit;
+	int count;
+
+	pr_debug("%s: stripe %llu checkp: %d\n", __func__,
+		(unsigned long long)sh->sector, checkp);
+
+	count = set_syndrome_sources(srcs, sh);
+	if (!checkp)
+		srcs[count] = NULL;
 
 	atomic_inc(&sh->count);
-	tx = async_trigger_callback(ASYNC_TX_DEP_ACK | ASYNC_TX_ACK, tx,
-		ops_complete_check, sh);
+	init_async_submit(&submit, ASYNC_TX_ACK, NULL, ops_complete_check,
+			  sh, to_addr_conv(sh, percpu));
+	async_syndrome_val(srcs, 0, count+2, STRIPE_SIZE,
+			   &sh->ops.zero_sum_result, percpu->spare_page, &submit);
 }
 
-static void raid5_run_ops(struct stripe_head *sh, unsigned long ops_request)
+static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
 {
 	int overlap_clear = 0, i, disks = sh->disks;
 	struct dma_async_tx_descriptor *tx = NULL;
+	raid5_conf_t *conf = sh->raid_conf;
+	int level = conf->level;
+	struct raid5_percpu *percpu;
+	unsigned long cpu;
 
+	cpu = get_cpu();
+	percpu = per_cpu_ptr(conf->percpu, cpu);
 	if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
 		ops_run_biofill(sh);
 		overlap_clear++;
 	}
 
 	if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
-		tx = ops_run_compute5(sh);
-		/* terminate the chain if postxor is not set to be run */
-		if (tx && !test_bit(STRIPE_OP_POSTXOR, &ops_request))
+		if (level < 6)
+			tx = ops_run_compute5(sh, percpu);
+		else {
+			if (sh->ops.target2 < 0 || sh->ops.target < 0)
+				tx = ops_run_compute6_1(sh, percpu);
+			else
+				tx = ops_run_compute6_2(sh, percpu);
+		}
+		/* terminate the chain if reconstruct is not set to be run */
+		if (tx && !test_bit(STRIPE_OP_RECONSTRUCT, &ops_request))
 			async_tx_ack(tx);
 	}
 
 	if (test_bit(STRIPE_OP_PREXOR, &ops_request))
-		tx = ops_run_prexor(sh, tx);
+		tx = ops_run_prexor(sh, percpu, tx);
 
 	if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
 		tx = ops_run_biodrain(sh, tx);
 		overlap_clear++;
 	}
 
-	if (test_bit(STRIPE_OP_POSTXOR, &ops_request))
-		ops_run_postxor(sh, tx);
+	if (test_bit(STRIPE_OP_RECONSTRUCT, &ops_request)) {
+		if (level < 6)
+			ops_run_reconstruct5(sh, percpu, tx);
+		else
+			ops_run_reconstruct6(sh, percpu, tx);
+	}
 
-	if (test_bit(STRIPE_OP_CHECK, &ops_request))
-		ops_run_check(sh);
+	if (test_bit(STRIPE_OP_CHECK, &ops_request)) {
+		if (sh->check_state == check_state_run)
+			ops_run_check_p(sh, percpu);
+		else if (sh->check_state == check_state_run_q)
+			ops_run_check_pq(sh, percpu, 0);
+		else if (sh->check_state == check_state_run_pq)
+			ops_run_check_pq(sh, percpu, 1);
+		else
+			BUG();
+	}
 
 	if (overlap_clear)
 		for (i = disks; i--; ) {
@@ -899,6 +1189,7 @@ static void raid5_run_ops(struct stripe_head *sh, unsigned long ops_request)
 			if (test_and_clear_bit(R5_Overlap, &dev->flags))
 				wake_up(&sh->raid_conf->wait_for_overlap);
 		}
+	put_cpu();
 }
 
 static int grow_one_stripe(raid5_conf_t *conf)
@@ -948,6 +1239,28 @@ static int grow_stripes(raid5_conf_t *conf, int num)
 	return 0;
 }
 
+/**
+ * scribble_len - return the required size of the scribble region
+ * @num - total number of disks in the array
+ *
+ * The size must be enough to contain:
+ * 1/ a struct page pointer for each device in the array +2
+ * 2/ room to convert each entry in (1) to its corresponding dma
+ *    (dma_map_page()) or page (page_address()) address.
+ *
+ * Note: the +2 is for the destination buffers of the ddf/raid6 case where we
+ * calculate over all devices (not just the data blocks), using zeros in place
+ * of the P and Q blocks.
+ */
+static size_t scribble_len(int num)
+{
+	size_t len;
+
+	len = sizeof(struct page *) * (num+2) + sizeof(addr_conv_t) * (num+2);
+
+	return len;
+}
+
 static int resize_stripes(raid5_conf_t *conf, int newsize)
 {
 	/* Make all the stripes able to hold 'newsize' devices.
@@ -976,6 +1289,7 @@ static int resize_stripes(raid5_conf_t *conf, int newsize)
 	struct stripe_head *osh, *nsh;
 	LIST_HEAD(newstripes);
 	struct disk_info *ndisks;
+	unsigned long cpu;
 	int err;
 	struct kmem_cache *sc;
 	int i;
@@ -1041,7 +1355,7 @@ static int resize_stripes(raid5_conf_t *conf, int newsize)
 	/* Step 3.
 	 * At this point, we are holding all the stripes so the array
 	 * is completely stalled, so now is a good time to resize
-	 * conf->disks.
+	 * conf->disks and the scribble region
 	 */
 	ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
 	if (ndisks) {
@@ -1052,10 +1366,30 @@ static int resize_stripes(raid5_conf_t *conf, int newsize)
 	} else
 		err = -ENOMEM;
 
+	get_online_cpus();
+	conf->scribble_len = scribble_len(newsize);
+	for_each_present_cpu(cpu) {
+		struct raid5_percpu *percpu;
+		void *scribble;
+
+		percpu = per_cpu_ptr(conf->percpu, cpu);
+		scribble = kmalloc(conf->scribble_len, GFP_NOIO);
+
+		if (scribble) {
+			kfree(percpu->scribble);
+			percpu->scribble = scribble;
+		} else {
+			err = -ENOMEM;
+			break;
+		}
+	}
+	put_online_cpus();
+
 	/* Step 4, return new stripes to service */
 	while(!list_empty(&newstripes)) {
 		nsh = list_entry(newstripes.next, struct stripe_head, lru);
 		list_del_init(&nsh->lru);
+
 		for (i=conf->raid_disks; i < newsize; i++)
 			if (nsh->dev[i].page == NULL) {
 				struct page *p = alloc_page(GFP_NOIO);
@@ -1594,258 +1928,13 @@ static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous)
 }
 
 
-
-/*
- * Copy data between a page in the stripe cache, and one or more bion
- * The page could align with the middle of the bio, or there could be
- * several bion, each with several bio_vecs, which cover part of the page
- * Multiple bion are linked together on bi_next.  There may be extras
- * at the end of this list.  We ignore them.
- */
-static void copy_data(int frombio, struct bio *bio,
-		     struct page *page,
-		     sector_t sector)
-{
-	char *pa = page_address(page);
-	struct bio_vec *bvl;
-	int i;
-	int page_offset;
-
-	if (bio->bi_sector >= sector)
-		page_offset = (signed)(bio->bi_sector - sector) * 512;
-	else
-		page_offset = (signed)(sector - bio->bi_sector) * -512;
-	bio_for_each_segment(bvl, bio, i) {
-		int len = bio_iovec_idx(bio,i)->bv_len;
-		int clen;
-		int b_offset = 0;
-
-		if (page_offset < 0) {
-			b_offset = -page_offset;
-			page_offset += b_offset;
-			len -= b_offset;
-		}
-
-		if (len > 0 && page_offset + len > STRIPE_SIZE)
-			clen = STRIPE_SIZE - page_offset;
-		else clen = len;
-
-		if (clen > 0) {
-			char *ba = __bio_kmap_atomic(bio, i, KM_USER0);
-			if (frombio)
-				memcpy(pa+page_offset, ba+b_offset, clen);
-			else
-				memcpy(ba+b_offset, pa+page_offset, clen);
-			__bio_kunmap_atomic(ba, KM_USER0);
-		}
-		if (clen < len) /* hit end of page */
-			break;
-		page_offset +=  len;
-	}
-}
-
-#define check_xor()	do {						  \
-				if (count == MAX_XOR_BLOCKS) {		  \
-				xor_blocks(count, STRIPE_SIZE, dest, ptr);\
-				count = 0;				  \
-			   }						  \
-			} while(0)
-
-static void compute_parity6(struct stripe_head *sh, int method)
-{
-	raid5_conf_t *conf = sh->raid_conf;
-	int i, pd_idx, qd_idx, d0_idx, disks = sh->disks, count;
-	int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
-	struct bio *chosen;
-	/**** FIX THIS: This could be very bad if disks is close to 256 ****/
-	void *ptrs[syndrome_disks+2];
-
-	pd_idx = sh->pd_idx;
-	qd_idx = sh->qd_idx;
-	d0_idx = raid6_d0(sh);
-
-	pr_debug("compute_parity, stripe %llu, method %d\n",
-		(unsigned long long)sh->sector, method);
-
-	switch(method) {
-	case READ_MODIFY_WRITE:
-		BUG();		/* READ_MODIFY_WRITE N/A for RAID-6 */
-	case RECONSTRUCT_WRITE:
-		for (i= disks; i-- ;)
-			if ( i != pd_idx && i != qd_idx && sh->dev[i].towrite ) {
-				chosen = sh->dev[i].towrite;
-				sh->dev[i].towrite = NULL;
-
-				if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
-					wake_up(&conf->wait_for_overlap);
-
-				BUG_ON(sh->dev[i].written);
-				sh->dev[i].written = chosen;
-			}
-		break;
-	case CHECK_PARITY:
-		BUG();		/* Not implemented yet */
-	}
-
-	for (i = disks; i--;)
-		if (sh->dev[i].written) {
-			sector_t sector = sh->dev[i].sector;
-			struct bio *wbi = sh->dev[i].written;
-			while (wbi && wbi->bi_sector < sector + STRIPE_SECTORS) {
-				copy_data(1, wbi, sh->dev[i].page, sector);
-				wbi = r5_next_bio(wbi, sector);
-			}
-
-			set_bit(R5_LOCKED, &sh->dev[i].flags);
-			set_bit(R5_UPTODATE, &sh->dev[i].flags);
-		}
-
-	/* Note that unlike RAID-5, the ordering of the disks matters greatly.*/
-
-	for (i = 0; i < disks; i++)
-		ptrs[i] = (void *)raid6_empty_zero_page;
-
-	count = 0;
-	i = d0_idx;
-	do {
-		int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
-
-		ptrs[slot] = page_address(sh->dev[i].page);
-		if (slot < syndrome_disks &&
-		    !test_bit(R5_UPTODATE, &sh->dev[i].flags)) {
-			printk(KERN_ERR "block %d/%d not uptodate "
-			       "on parity calc\n", i, count);
-			BUG();
-		}
-
-		i = raid6_next_disk(i, disks);
-	} while (i != d0_idx);
-	BUG_ON(count != syndrome_disks);
-
-	raid6_call.gen_syndrome(syndrome_disks+2, STRIPE_SIZE, ptrs);
-
-	switch(method) {
-	case RECONSTRUCT_WRITE:
-		set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
-		set_bit(R5_UPTODATE, &sh->dev[qd_idx].flags);
-		set_bit(R5_LOCKED,   &sh->dev[pd_idx].flags);
-		set_bit(R5_LOCKED,   &sh->dev[qd_idx].flags);
-		break;
-	case UPDATE_PARITY:
-		set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
-		set_bit(R5_UPTODATE, &sh->dev[qd_idx].flags);
-		break;
-	}
-}
-
-
-/* Compute one missing block */
-static void compute_block_1(struct stripe_head *sh, int dd_idx, int nozero)
-{
-	int i, count, disks = sh->disks;
-	void *ptr[MAX_XOR_BLOCKS], *dest, *p;
-	int qd_idx = sh->qd_idx;
-
-	pr_debug("compute_block_1, stripe %llu, idx %d\n",
-		(unsigned long long)sh->sector, dd_idx);
-
-	if ( dd_idx == qd_idx ) {
-		/* We're actually computing the Q drive */
-		compute_parity6(sh, UPDATE_PARITY);
-	} else {
-		dest = page_address(sh->dev[dd_idx].page);
-		if (!nozero) memset(dest, 0, STRIPE_SIZE);
-		count = 0;
-		for (i = disks ; i--; ) {
-			if (i == dd_idx || i == qd_idx)
-				continue;
-			p = page_address(sh->dev[i].page);
-			if (test_bit(R5_UPTODATE, &sh->dev[i].flags))
-				ptr[count++] = p;
-			else
-				printk("compute_block() %d, stripe %llu, %d"
-				       " not present\n", dd_idx,
-				       (unsigned long long)sh->sector, i);
-
-			check_xor();
-		}
-		if (count)
-			xor_blocks(count, STRIPE_SIZE, dest, ptr);
-		if (!nozero) set_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
-		else clear_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
-	}
-}
-
-/* Compute two missing blocks */
-static void compute_block_2(struct stripe_head *sh, int dd_idx1, int dd_idx2)
-{
-	int i, count, disks = sh->disks;
-	int syndrome_disks = sh->ddf_layout ? disks : disks-2;
-	int d0_idx = raid6_d0(sh);
-	int faila = -1, failb = -1;
-	/**** FIX THIS: This could be very bad if disks is close to 256 ****/
-	void *ptrs[syndrome_disks+2];
-
-	for (i = 0; i < disks ; i++)
-		ptrs[i] = (void *)raid6_empty_zero_page;
-	count = 0;
-	i = d0_idx;
-	do {
-		int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
-
-		ptrs[slot] = page_address(sh->dev[i].page);
-
-		if (i == dd_idx1)
-			faila = slot;
-		if (i == dd_idx2)
-			failb = slot;
-		i = raid6_next_disk(i, disks);
-	} while (i != d0_idx);
-	BUG_ON(count != syndrome_disks);
-
-	BUG_ON(faila == failb);
-	if ( failb < faila ) { int tmp = faila; faila = failb; failb = tmp; }
-
-	pr_debug("compute_block_2, stripe %llu, idx %d,%d (%d,%d)\n",
-		 (unsigned long long)sh->sector, dd_idx1, dd_idx2,
-		 faila, failb);
-
-	if (failb == syndrome_disks+1) {
-		/* Q disk is one of the missing disks */
-		if (faila == syndrome_disks) {
-			/* Missing P+Q, just recompute */
-			compute_parity6(sh, UPDATE_PARITY);
-			return;
-		} else {
-			/* We're missing D+Q; recompute D from P */
-			compute_block_1(sh, ((dd_idx1 == sh->qd_idx) ?
-					     dd_idx2 : dd_idx1),
-					0);
-			compute_parity6(sh, UPDATE_PARITY); /* Is this necessary? */
-			return;
-		}
-	}
-
-	/* We're missing D+P or D+D; */
-	if (failb == syndrome_disks) {
-		/* We're missing D+P. */
-		raid6_datap_recov(syndrome_disks+2, STRIPE_SIZE, faila, ptrs);
-	} else {
-		/* We're missing D+D. */
-		raid6_2data_recov(syndrome_disks+2, STRIPE_SIZE, faila, failb,
-				  ptrs);
-	}
-
-	/* Both the above update both missing blocks */
-	set_bit(R5_UPTODATE, &sh->dev[dd_idx1].flags);
-	set_bit(R5_UPTODATE, &sh->dev[dd_idx2].flags);
-}
-
 static void
-schedule_reconstruction5(struct stripe_head *sh, struct stripe_head_state *s,
+schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
 			 int rcw, int expand)
 {
 	int i, pd_idx = sh->pd_idx, disks = sh->disks;
+	raid5_conf_t *conf = sh->raid_conf;
+	int level = conf->level;
 
 	if (rcw) {
 		/* if we are not expanding this is a proper write request, and
@@ -1858,7 +1947,7 @@ schedule_reconstruction5(struct stripe_head *sh, struct stripe_head_state *s,
 		} else
 			sh->reconstruct_state = reconstruct_state_run;
 
-		set_bit(STRIPE_OP_POSTXOR, &s->ops_request);
+		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
 
 		for (i = disks; i--; ) {
 			struct r5dev *dev = &sh->dev[i];
@@ -1871,17 +1960,18 @@ schedule_reconstruction5(struct stripe_head *sh, struct stripe_head_state *s,
 				s->locked++;
 			}
 		}
-		if (s->locked + 1 == disks)
+		if (s->locked + conf->max_degraded == disks)
 			if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
-				atomic_inc(&sh->raid_conf->pending_full_writes);
+				atomic_inc(&conf->pending_full_writes);
 	} else {
+		BUG_ON(level == 6);
 		BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
 			test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
 
 		sh->reconstruct_state = reconstruct_state_prexor_drain_run;
 		set_bit(STRIPE_OP_PREXOR, &s->ops_request);
 		set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
-		set_bit(STRIPE_OP_POSTXOR, &s->ops_request);
+		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
 
 		for (i = disks; i--; ) {
 			struct r5dev *dev = &sh->dev[i];
@@ -1899,13 +1989,22 @@ schedule_reconstruction5(struct stripe_head *sh, struct stripe_head_state *s,
 		}
 	}
 
-	/* keep the parity disk locked while asynchronous operations
+	/* keep the parity disk(s) locked while asynchronous operations
 	 * are in flight
 	 */
 	set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
 	clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
 	s->locked++;
 
+	if (level == 6) {
+		int qd_idx = sh->qd_idx;
+		struct r5dev *dev = &sh->dev[qd_idx];
+
+		set_bit(R5_LOCKED, &dev->flags);
+		clear_bit(R5_UPTODATE, &dev->flags);
+		s->locked++;
+	}
+
 	pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
 		__func__, (unsigned long long)sh->sector,
 		s->locked, s->ops_request);
@@ -1986,13 +2085,6 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, in
 
 static void end_reshape(raid5_conf_t *conf);
 
-static int page_is_zero(struct page *p)
-{
-	char *a = page_address(p);
-	return ((*(u32*)a) == 0 &&
-		memcmp(a, a+4, STRIPE_SIZE-4)==0);
-}
-
 static void stripe_set_idx(sector_t stripe, raid5_conf_t *conf, int previous,
 			    struct stripe_head *sh)
 {
@@ -2133,9 +2225,10 @@ static int fetch_block5(struct stripe_head *sh, struct stripe_head_state *s,
 			set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
 			set_bit(R5_Wantcompute, &dev->flags);
 			sh->ops.target = disk_idx;
+			sh->ops.target2 = -1;
 			s->req_compute = 1;
 			/* Careful: from this point on 'uptodate' is in the eye
-			 * of raid5_run_ops which services 'compute' operations
+			 * of raid_run_ops which services 'compute' operations
 			 * before writes. R5_Wantcompute flags a block that will
 			 * be R5_UPTODATE by the time it is needed for a
 			 * subsequent operation.
@@ -2174,61 +2267,104 @@ static void handle_stripe_fill5(struct stripe_head *sh,
 	set_bit(STRIPE_HANDLE, &sh->state);
 }
 
-static void handle_stripe_fill6(struct stripe_head *sh,
-			struct stripe_head_state *s, struct r6_state *r6s,
-			int disks)
+/* fetch_block6 - checks the given member device to see if its data needs
+ * to be read or computed to satisfy a request.
+ *
+ * Returns 1 when no more member devices need to be checked, otherwise returns
+ * 0 to tell the loop in handle_stripe_fill6 to continue
+ */
+static int fetch_block6(struct stripe_head *sh, struct stripe_head_state *s,
+			 struct r6_state *r6s, int disk_idx, int disks)
 {
-	int i;
-	for (i = disks; i--; ) {
-		struct r5dev *dev = &sh->dev[i];
-		if (!test_bit(R5_LOCKED, &dev->flags) &&
-		    !test_bit(R5_UPTODATE, &dev->flags) &&
-		    (dev->toread || (dev->towrite &&
-		     !test_bit(R5_OVERWRITE, &dev->flags)) ||
-		     s->syncing || s->expanding ||
-		     (s->failed >= 1 &&
-		      (sh->dev[r6s->failed_num[0]].toread ||
-		       s->to_write)) ||
-		     (s->failed >= 2 &&
-		      (sh->dev[r6s->failed_num[1]].toread ||
-		       s->to_write)))) {
-			/* we would like to get this block, possibly
-			 * by computing it, but we might not be able to
+	struct r5dev *dev = &sh->dev[disk_idx];
+	struct r5dev *fdev[2] = { &sh->dev[r6s->failed_num[0]],
+				  &sh->dev[r6s->failed_num[1]] };
+
+	if (!test_bit(R5_LOCKED, &dev->flags) &&
+	    !test_bit(R5_UPTODATE, &dev->flags) &&
+	    (dev->toread ||
+	     (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
+	     s->syncing || s->expanding ||
+	     (s->failed >= 1 &&
+	      (fdev[0]->toread || s->to_write)) ||
+	     (s->failed >= 2 &&
+	      (fdev[1]->toread || s->to_write)))) {
+		/* we would like to get this block, possibly by computing it,
+		 * otherwise read it if the backing disk is insync
+		 */
+		BUG_ON(test_bit(R5_Wantcompute, &dev->flags));
+		BUG_ON(test_bit(R5_Wantread, &dev->flags));
+		if ((s->uptodate == disks - 1) &&
+		    (s->failed && (disk_idx == r6s->failed_num[0] ||
+				   disk_idx == r6s->failed_num[1]))) {
+			/* have disk failed, and we're requested to fetch it;
+			 * do compute it
 			 */
-			if ((s->uptodate == disks - 1) &&
-			    (s->failed && (i == r6s->failed_num[0] ||
-					   i == r6s->failed_num[1]))) {
-				pr_debug("Computing stripe %llu block %d\n",
-				       (unsigned long long)sh->sector, i);
-				compute_block_1(sh, i, 0);
-				s->uptodate++;
-			} else if ( s->uptodate == disks-2 && s->failed >= 2 ) {
-				/* Computing 2-failure is *very* expensive; only
-				 * do it if failed >= 2
-				 */
-				int other;
-				for (other = disks; other--; ) {
-					if (other == i)
-						continue;
-					if (!test_bit(R5_UPTODATE,
-					      &sh->dev[other].flags))
-						break;
-				}
-				BUG_ON(other < 0);
-				pr_debug("Computing stripe %llu blocks %d,%d\n",
-				       (unsigned long long)sh->sector,
-				       i, other);
-				compute_block_2(sh, i, other);
-				s->uptodate += 2;
-			} else if (test_bit(R5_Insync, &dev->flags)) {
-				set_bit(R5_LOCKED, &dev->flags);
-				set_bit(R5_Wantread, &dev->flags);
-				s->locked++;
-				pr_debug("Reading block %d (sync=%d)\n",
-					i, s->syncing);
+			pr_debug("Computing stripe %llu block %d\n",
+			       (unsigned long long)sh->sector, disk_idx);
+			set_bit(STRIPE_COMPUTE_RUN, &sh->state);
+			set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
+			set_bit(R5_Wantcompute, &dev->flags);
+			sh->ops.target = disk_idx;
+			sh->ops.target2 = -1; /* no 2nd target */
+			s->req_compute = 1;
+			s->uptodate++;
+			return 1;
+		} else if (s->uptodate == disks-2 && s->failed >= 2) {
+			/* Computing 2-failure is *very* expensive; only
+			 * do it if failed >= 2
+			 */
+			int other;
+			for (other = disks; other--; ) {
+				if (other == disk_idx)
+					continue;
+				if (!test_bit(R5_UPTODATE,
+				      &sh->dev[other].flags))
+					break;
 			}
+			BUG_ON(other < 0);
+			pr_debug("Computing stripe %llu blocks %d,%d\n",
+			       (unsigned long long)sh->sector,
+			       disk_idx, other);
+			set_bit(STRIPE_COMPUTE_RUN, &sh->state);
+			set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
+			set_bit(R5_Wantcompute, &sh->dev[disk_idx].flags);
+			set_bit(R5_Wantcompute, &sh->dev[other].flags);
+			sh->ops.target = disk_idx;
+			sh->ops.target2 = other;
+			s->uptodate += 2;
+			s->req_compute = 1;
+			return 1;
+		} else if (test_bit(R5_Insync, &dev->flags)) {
+			set_bit(R5_LOCKED, &dev->flags);
+			set_bit(R5_Wantread, &dev->flags);
+			s->locked++;
+			pr_debug("Reading block %d (sync=%d)\n",
+				disk_idx, s->syncing);
 		}
 	}
+
+	return 0;
+}
+
+/**
+ * handle_stripe_fill6 - read or compute data to satisfy pending requests.
+ */
+static void handle_stripe_fill6(struct stripe_head *sh,
+			struct stripe_head_state *s, struct r6_state *r6s,
+			int disks)
+{
+	int i;
+
+	/* look for blocks to read/compute, skip this if a compute
+	 * is already in flight, or if the stripe contents are in the
+	 * midst of changing due to a write
+	 */
+	if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
+	    !sh->reconstruct_state)
+		for (i = disks; i--; )
+			if (fetch_block6(sh, s, r6s, i, disks))
+				break;
 	set_bit(STRIPE_HANDLE, &sh->state);
 }
 
@@ -2362,114 +2498,61 @@ static void handle_stripe_dirtying5(raid5_conf_t *conf,
 	 */
 	/* since handle_stripe can be called at any time we need to handle the
 	 * case where a compute block operation has been submitted and then a
-	 * subsequent call wants to start a write request.  raid5_run_ops only
-	 * handles the case where compute block and postxor are requested
+	 * subsequent call wants to start a write request.  raid_run_ops only
+	 * handles the case where compute block and reconstruct are requested
 	 * simultaneously.  If this is not the case then new writes need to be
 	 * held off until the compute completes.
 	 */
 	if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
 	    (s->locked == 0 && (rcw == 0 || rmw == 0) &&
 	    !test_bit(STRIPE_BIT_DELAY, &sh->state)))
-		schedule_reconstruction5(sh, s, rcw == 0, 0);
+		schedule_reconstruction(sh, s, rcw == 0, 0);
 }
 
 static void handle_stripe_dirtying6(raid5_conf_t *conf,
 		struct stripe_head *sh,	struct stripe_head_state *s,
 		struct r6_state *r6s, int disks)
 {
-	int rcw = 0, must_compute = 0, pd_idx = sh->pd_idx, i;
+	int rcw = 0, pd_idx = sh->pd_idx, i;
 	int qd_idx = sh->qd_idx;
+
+	set_bit(STRIPE_HANDLE, &sh->state);
 	for (i = disks; i--; ) {
 		struct r5dev *dev = &sh->dev[i];
-		/* Would I have to read this buffer for reconstruct_write */
-		if (!test_bit(R5_OVERWRITE, &dev->flags)
-		    && i != pd_idx && i != qd_idx
-		    && (!test_bit(R5_LOCKED, &dev->flags)
-			    ) &&
-		    !test_bit(R5_UPTODATE, &dev->flags)) {
-			if (test_bit(R5_Insync, &dev->flags)) rcw++;
-			else {
-				pr_debug("raid6: must_compute: "
-					"disk %d flags=%#lx\n", i, dev->flags);
-				must_compute++;
+		/* check if we haven't enough data */
+		if (!test_bit(R5_OVERWRITE, &dev->flags) &&
+		    i != pd_idx && i != qd_idx &&
+		    !test_bit(R5_LOCKED, &dev->flags) &&
+		    !(test_bit(R5_UPTODATE, &dev->flags) ||
+		      test_bit(R5_Wantcompute, &dev->flags))) {
+			rcw++;
+			if (!test_bit(R5_Insync, &dev->flags))
+				continue; /* it's a failed drive */
+
+			if (
+			  test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
+				pr_debug("Read_old stripe %llu "
+					"block %d for Reconstruct\n",
+				     (unsigned long long)sh->sector, i);
+				set_bit(R5_LOCKED, &dev->flags);
+				set_bit(R5_Wantread, &dev->flags);
+				s->locked++;
+			} else {
+				pr_debug("Request delayed stripe %llu "
+					"block %d for Reconstruct\n",
+				     (unsigned long long)sh->sector, i);
+				set_bit(STRIPE_DELAYED, &sh->state);
+				set_bit(STRIPE_HANDLE, &sh->state);
 			}
 		}
 	}
-	pr_debug("for sector %llu, rcw=%d, must_compute=%d\n",
-	       (unsigned long long)sh->sector, rcw, must_compute);
-	set_bit(STRIPE_HANDLE, &sh->state);
-
-	if (rcw > 0)
-		/* want reconstruct write, but need to get some data */
-		for (i = disks; i--; ) {
-			struct r5dev *dev = &sh->dev[i];
-			if (!test_bit(R5_OVERWRITE, &dev->flags)
-			    && !(s->failed == 0 && (i == pd_idx || i == qd_idx))
-			    && !test_bit(R5_LOCKED, &dev->flags) &&
-			    !test_bit(R5_UPTODATE, &dev->flags) &&
-			    test_bit(R5_Insync, &dev->flags)) {
-				if (
-				  test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
-					pr_debug("Read_old stripe %llu "
-						"block %d for Reconstruct\n",
-					     (unsigned long long)sh->sector, i);
-					set_bit(R5_LOCKED, &dev->flags);
-					set_bit(R5_Wantread, &dev->flags);
-					s->locked++;
-				} else {
-					pr_debug("Request delayed stripe %llu "
-						"block %d for Reconstruct\n",
-					     (unsigned long long)sh->sector, i);
-					set_bit(STRIPE_DELAYED, &sh->state);
-					set_bit(STRIPE_HANDLE, &sh->state);
-				}
-			}
-		}
 	/* now if nothing is locked, and if we have enough data, we can start a
 	 * write request
 	 */
-	if (s->locked == 0 && rcw == 0 &&
+	if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
+	    s->locked == 0 && rcw == 0 &&
 	    !test_bit(STRIPE_BIT_DELAY, &sh->state)) {
-		if (must_compute > 0) {
-			/* We have failed blocks and need to compute them */
-			switch (s->failed) {
-			case 0:
-				BUG();
-			case 1:
-				compute_block_1(sh, r6s->failed_num[0], 0);
-				break;
-			case 2:
-				compute_block_2(sh, r6s->failed_num[0],
-						r6s->failed_num[1]);
-				break;
-			default: /* This request should have been failed? */
-				BUG();
-			}
-		}
-
-		pr_debug("Computing parity for stripe %llu\n",
-			(unsigned long long)sh->sector);
-		compute_parity6(sh, RECONSTRUCT_WRITE);
-		/* now every locked buffer is ready to be written */
-		for (i = disks; i--; )
-			if (test_bit(R5_LOCKED, &sh->dev[i].flags)) {
-				pr_debug("Writing stripe %llu block %d\n",
-				       (unsigned long long)sh->sector, i);
-				s->locked++;
-				set_bit(R5_Wantwrite, &sh->dev[i].flags);
-			}
-		if (s->locked == disks)
-			if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
-				atomic_inc(&conf->pending_full_writes);
-		/* after a RECONSTRUCT_WRITE, the stripe MUST be in-sync */
-		set_bit(STRIPE_INSYNC, &sh->state);
-
-		if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
-			atomic_dec(&conf->preread_active_stripes);
-			if (atomic_read(&conf->preread_active_stripes) <
-			    IO_THRESHOLD)
-				md_wakeup_thread(conf->mddev->thread);
-		}
+		schedule_reconstruction(sh, s, 1, 0);
 	}
 }
 
@@ -2528,7 +2611,7 @@ static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh,
 		 * we are done.  Otherwise update the mismatch count and repair
 		 * parity if !MD_RECOVERY_CHECK
 		 */
-		if (sh->ops.zero_sum_result == 0)
+		if ((sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) == 0)
 			/* parity is correct (on disc,
 			 * not in buffer any more)
 			 */
@@ -2545,6 +2628,7 @@ static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh,
 				set_bit(R5_Wantcompute,
 					&sh->dev[sh->pd_idx].flags);
 				sh->ops.target = sh->pd_idx;
+				sh->ops.target2 = -1;
 				s->uptodate++;
 			}
 		}
@@ -2561,67 +2645,74 @@ static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh,
 
 
 static void handle_parity_checks6(raid5_conf_t *conf, struct stripe_head *sh,
-				struct stripe_head_state *s,
-				struct r6_state *r6s, struct page *tmp_page,
-				int disks)
+				  struct stripe_head_state *s,
+				  struct r6_state *r6s, int disks)
 {
-	int update_p = 0, update_q = 0;
-	struct r5dev *dev;
 	int pd_idx = sh->pd_idx;
 	int qd_idx = sh->qd_idx;
+	struct r5dev *dev;
 
 	set_bit(STRIPE_HANDLE, &sh->state);
 
 	BUG_ON(s->failed > 2);
-	BUG_ON(s->uptodate < disks);
+
 	/* Want to check and possibly repair P and Q.
 	 * However there could be one 'failed' device, in which
 	 * case we can only check one of them, possibly using the
 	 * other to generate missing data
 	 */
 
-	/* If !tmp_page, we cannot do the calculations,
-	 * but as we have set STRIPE_HANDLE, we will soon be called
-	 * by stripe_handle with a tmp_page - just wait until then.
-	 */
-	if (tmp_page) {
+	switch (sh->check_state) {
+	case check_state_idle:
+		/* start a new check operation if there are < 2 failures */
 		if (s->failed == r6s->q_failed) {
-			/* The only possible failed device holds 'Q', so it
+			/* The only possible failed device holds Q, so it
 			 * makes sense to check P (If anything else were failed,
 			 * we would have used P to recreate it).
 			 */
-			compute_block_1(sh, pd_idx, 1);
-			if (!page_is_zero(sh->dev[pd_idx].page)) {
-				compute_block_1(sh, pd_idx, 0);
-				update_p = 1;
-			}
+			sh->check_state = check_state_run;
 		}
 		if (!r6s->q_failed && s->failed < 2) {
-			/* q is not failed, and we didn't use it to generate
+			/* Q is not failed, and we didn't use it to generate
 			 * anything, so it makes sense to check it
 			 */
-			memcpy(page_address(tmp_page),
-			       page_address(sh->dev[qd_idx].page),
-			       STRIPE_SIZE);
-			compute_parity6(sh, UPDATE_PARITY);
-			if (memcmp(page_address(tmp_page),
-				   page_address(sh->dev[qd_idx].page),
-				   STRIPE_SIZE) != 0) {
-				clear_bit(STRIPE_INSYNC, &sh->state);
-				update_q = 1;
-			}
+			if (sh->check_state == check_state_run)
+				sh->check_state = check_state_run_pq;
+			else
+				sh->check_state = check_state_run_q;
 		}
-		if (update_p || update_q) {
-			conf->mddev->resync_mismatches += STRIPE_SECTORS;
-			if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
-				/* don't try to repair!! */
-				update_p = update_q = 0;
+
+		/* discard potentially stale zero_sum_result */
+		sh->ops.zero_sum_result = 0;
+
+		if (sh->check_state == check_state_run) {
+			/* async_xor_zero_sum destroys the contents of P */
+			clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
+			s->uptodate--;
 		}
+		if (sh->check_state >= check_state_run &&
+		    sh->check_state <= check_state_run_pq) {
+			/* async_syndrome_zero_sum preserves P and Q, so
+			 * no need to mark them !uptodate here
+			 */
+			set_bit(STRIPE_OP_CHECK, &s->ops_request);
+			break;
+		}
+
+		/* we have 2-disk failure */
+		BUG_ON(s->failed != 2);
+		/* fall through */
+	case check_state_compute_result:
+		sh->check_state = check_state_idle;
+
+		/* check that a write has not made the stripe insync */
+		if (test_bit(STRIPE_INSYNC, &sh->state))
+			break;
 
 		/* now write out any block on a failed drive,
-		 * or P or Q if they need it
+		 * or P or Q if they were recomputed
 		 */
-
+		BUG_ON(s->uptodate < disks - 1); /* We don't need Q to recover */
 		if (s->failed == 2) {
 			dev = &sh->dev[r6s->failed_num[1]];
 			s->locked++;
@@ -2634,14 +2725,13 @@ static void handle_parity_checks6(raid5_conf_t *conf, struct stripe_head *sh,
 			set_bit(R5_LOCKED, &dev->flags);
 			set_bit(R5_Wantwrite, &dev->flags);
 		}
-
-		if (update_p) {
+		if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
 			dev = &sh->dev[pd_idx];
 			s->locked++;
 			set_bit(R5_LOCKED, &dev->flags);
 			set_bit(R5_Wantwrite, &dev->flags);
 		}
-		if (update_q) {
+		if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
 			dev = &sh->dev[qd_idx];
 			s->locked++;
 			set_bit(R5_LOCKED, &dev->flags);
@@ -2650,6 +2740,70 @@ static void handle_parity_checks6(raid5_conf_t *conf, struct stripe_head *sh,
 		clear_bit(STRIPE_DEGRADED, &sh->state);
 
 		set_bit(STRIPE_INSYNC, &sh->state);
+		break;
+	case check_state_run:
+	case check_state_run_q:
+	case check_state_run_pq:
+		break; /* we will be called again upon completion */
+	case check_state_check_result:
+		sh->check_state = check_state_idle;
+
+		/* handle a successful check operation, if parity is correct
+		 * we are done.  Otherwise update the mismatch count and repair
+		 * parity if !MD_RECOVERY_CHECK
+		 */
+		if (sh->ops.zero_sum_result == 0) {
+			/* both parities are correct */
+			if (!s->failed)
+				set_bit(STRIPE_INSYNC, &sh->state);
+			else {
+				/* in contrast to the raid5 case we can validate
+				 * parity, but still have a failure to write
+				 * back
+				 */
+				sh->check_state = check_state_compute_result;
+				/* Returning at this point means that we may go
+				 * off and bring p and/or q uptodate again so
+				 * we make sure to check zero_sum_result again
+				 * to verify if p or q need writeback
+				 */
+			}
+		} else {
+			conf->mddev->resync_mismatches += STRIPE_SECTORS;
+			if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
+				/* don't try to repair!! */
+				set_bit(STRIPE_INSYNC, &sh->state);
+			else {
+				int *target = &sh->ops.target;
+
+				sh->ops.target = -1;
+				sh->ops.target2 = -1;
+				sh->check_state = check_state_compute_run;
+				set_bit(STRIPE_COMPUTE_RUN, &sh->state);
+				set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
+				if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
+					set_bit(R5_Wantcompute,
+						&sh->dev[pd_idx].flags);
+					*target = pd_idx;
+					target = &sh->ops.target2;
+					s->uptodate++;
+				}
+				if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
+					set_bit(R5_Wantcompute,
+						&sh->dev[qd_idx].flags);
+					*target = qd_idx;
+					s->uptodate++;
+				}
+			}
+		}
+		break;
+	case check_state_compute_run:
+		break;
+	default:
+		printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
+		       __func__, sh->check_state,
+		       (unsigned long long) sh->sector);
+		BUG();
 	}
 }
 
@@ -2667,6 +2821,7 @@ static void handle_stripe_expansion(raid5_conf_t *conf, struct stripe_head *sh,
 		if (i != sh->pd_idx && i != sh->qd_idx) {
 			int dd_idx, j;
 			struct stripe_head *sh2;
+			struct async_submit_ctl submit;
 
 			sector_t bn = compute_blocknr(sh, i, 1);
 			sector_t s = raid5_compute_sector(conf, bn, 0,
@@ -2686,9 +2841,10 @@ static void handle_stripe_expansion(raid5_conf_t *conf, struct stripe_head *sh,
 			}
 
 			/* place all the copies on one channel */
+			init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
 			tx = async_memcpy(sh2->dev[dd_idx].page,
-				sh->dev[i].page, 0, 0, STRIPE_SIZE,
-				ASYNC_TX_DEP_ACK, tx, NULL, NULL);
+					  sh->dev[i].page, 0, 0, STRIPE_SIZE,
+					  &submit);
 
 			set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
 			set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
@@ -2974,7 +3130,7 @@ static bool handle_stripe5(struct stripe_head *sh)
 		/* Need to write out all blocks after computing parity */
 		sh->disks = conf->raid_disks;
 		stripe_set_idx(sh->sector, conf, 0, sh);
-		schedule_reconstruction5(sh, &s, 1, 1);
+		schedule_reconstruction(sh, &s, 1, 1);
 	} else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
 		clear_bit(STRIPE_EXPAND_READY, &sh->state);
 		atomic_dec(&conf->reshape_stripes);
@@ -2994,7 +3150,7 @@ static bool handle_stripe5(struct stripe_head *sh)
 		md_wait_for_blocked_rdev(blocked_rdev, conf->mddev);
 
 	if (s.ops_request)
-		raid5_run_ops(sh, s.ops_request);
+		raid_run_ops(sh, s.ops_request);
 
 	ops_run_io(sh, &s);
 
@@ -3003,7 +3159,7 @@ static bool handle_stripe5(struct stripe_head *sh)
 	return blocked_rdev == NULL;
 }
 
-static bool handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
+static bool handle_stripe6(struct stripe_head *sh)
 {
 	raid5_conf_t *conf = sh->raid_conf;
 	int disks = sh->disks;
@@ -3015,9 +3171,10 @@ static bool handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
 	mdk_rdev_t *blocked_rdev = NULL;
 
 	pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
-		"pd_idx=%d, qd_idx=%d\n",
+		"pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
 	       (unsigned long long)sh->sector, sh->state,
-	       atomic_read(&sh->count), pd_idx, qd_idx);
+	       atomic_read(&sh->count), pd_idx, qd_idx,
+	       sh->check_state, sh->reconstruct_state);
 	memset(&s, 0, sizeof(s));
 
 	spin_lock(&sh->lock);
@@ -3037,35 +3194,24 @@ static bool handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
 
 		pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
 			i, dev->flags, dev->toread, dev->towrite, dev->written);
-		/* maybe we can reply to a read */
-		if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread) {
-			struct bio *rbi, *rbi2;
-			pr_debug("Return read for disc %d\n", i);
-			spin_lock_irq(&conf->device_lock);
-			rbi = dev->toread;
-			dev->toread = NULL;
-			if (test_and_clear_bit(R5_Overlap, &dev->flags))
-				wake_up(&conf->wait_for_overlap);
-			spin_unlock_irq(&conf->device_lock);
-			while (rbi && rbi->bi_sector < dev->sector + STRIPE_SECTORS) {
-				copy_data(0, rbi, dev->page, dev->sector);
-				rbi2 = r5_next_bio(rbi, dev->sector);
-				spin_lock_irq(&conf->device_lock);
-				if (!raid5_dec_bi_phys_segments(rbi)) {
-					rbi->bi_next = return_bi;
-					return_bi = rbi;
-				}
-				spin_unlock_irq(&conf->device_lock);
-				rbi = rbi2;
-			}
-		}
+		/* maybe we can reply to a read
+		 *
+		 * new wantfill requests are only permitted while
+		 * ops_complete_biofill is guaranteed to be inactive
+		 */
+		if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
+		    !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
+			set_bit(R5_Wantfill, &dev->flags);
 
 		/* now count some things */
 		if (test_bit(R5_LOCKED, &dev->flags)) s.locked++;
 		if (test_bit(R5_UPTODATE, &dev->flags)) s.uptodate++;
+		if (test_bit(R5_Wantcompute, &dev->flags))
+			BUG_ON(++s.compute > 2);
 
-
-		if (dev->toread)
+		if (test_bit(R5_Wantfill, &dev->flags)) {
+			s.to_fill++;
+		} else if (dev->toread)
 			s.to_read++;
 		if (dev->towrite) {
 			s.to_write++;
@@ -3106,6 +3252,11 @@ static bool handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
 		blocked_rdev = NULL;
 	}
 
+	if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
+		set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
+		set_bit(STRIPE_BIOFILL_RUN, &sh->state);
+	}
+
 	pr_debug("locked=%d uptodate=%d to_read=%d"
 	       " to_write=%d failed=%d failed_num=%d,%d\n",
 	       s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
@@ -3146,19 +3297,62 @@ static bool handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
 	 * or to load a block that is being partially written.
 	 */
 	if (s.to_read || s.non_overwrite || (s.to_write && s.failed) ||
-	    (s.syncing && (s.uptodate < disks)) || s.expanding)
+	    (s.syncing && (s.uptodate + s.compute < disks)) || s.expanding)
 		handle_stripe_fill6(sh, &s, &r6s, disks);
 
-	/* now to consider writing and what else, if anything should be read */
-	if (s.to_write)
+	/* Now we check to see if any write operations have recently
+	 * completed
+	 */
+	if (sh->reconstruct_state == reconstruct_state_drain_result) {
+		int qd_idx = sh->qd_idx;
+
+		sh->reconstruct_state = reconstruct_state_idle;
+		/* All the 'written' buffers and the parity blocks are ready to
+		 * be written back to disk
+		 */
+		BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags));
+		BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[qd_idx].flags));
+		for (i = disks; i--; ) {
+			dev = &sh->dev[i];
+			if (test_bit(R5_LOCKED, &dev->flags) &&
+			    (i == sh->pd_idx || i == qd_idx ||
+			     dev->written)) {
+				pr_debug("Writing block %d\n", i);
+				BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
+				set_bit(R5_Wantwrite, &dev->flags);
+				if (!test_bit(R5_Insync, &dev->flags) ||
+				    ((i == sh->pd_idx || i == qd_idx) &&
+				      s.failed == 0))
+					set_bit(STRIPE_INSYNC, &sh->state);
+			}
+		}
+		if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
+			atomic_dec(&conf->preread_active_stripes);
+			if (atomic_read(&conf->preread_active_stripes) <
+				IO_THRESHOLD)
+				md_wakeup_thread(conf->mddev->thread);
+		}
+	}
+
+	/* Now to consider new write requests and what else, if anything
+	 * should be read.  We do not handle new writes when:
+	 * 1/ A 'write' operation (copy+gen_syndrome) is already in flight.
+	 * 2/ A 'check' operation is in flight, as it may clobber the parity
+	 *    block.
+	 */
+	if (s.to_write && !sh->reconstruct_state && !sh->check_state)
 		handle_stripe_dirtying6(conf, sh, &s, &r6s, disks);
 
 	/* maybe we need to check and possibly fix the parity for this stripe
 	 * Any reads will already have been scheduled, so we just see if enough
-	 * data is available
+	 * data is available.  The parity check is held off while parity
+	 * dependent operations are in flight.
 	 */
-	if (s.syncing && s.locked == 0 && !test_bit(STRIPE_INSYNC, &sh->state))
-		handle_parity_checks6(conf, sh, &s, &r6s, tmp_page, disks);
+	if (sh->check_state ||
+	    (s.syncing && s.locked == 0 &&
+	     !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
+	     !test_bit(STRIPE_INSYNC, &sh->state)))
+		handle_parity_checks6(conf, sh, &s, &r6s, disks);
 
 	if (s.syncing && s.locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
 		md_done_sync(conf->mddev, STRIPE_SECTORS,1);
@@ -3179,15 +3373,29 @@ static bool handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
 					set_bit(R5_Wantwrite, &dev->flags);
 					set_bit(R5_ReWrite, &dev->flags);
 					set_bit(R5_LOCKED, &dev->flags);
+					s.locked++;
 				} else {
 					/* let's read it back */
 					set_bit(R5_Wantread, &dev->flags);
 					set_bit(R5_LOCKED, &dev->flags);
+					s.locked++;
 				}
 			}
 		}
 
-	if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state)) {
+	/* Finish reconstruct operations initiated by the expansion process */
+	if (sh->reconstruct_state == reconstruct_state_result) {
+		sh->reconstruct_state = reconstruct_state_idle;
+		clear_bit(STRIPE_EXPANDING, &sh->state);
+		for (i = conf->raid_disks; i--; ) {
+			set_bit(R5_Wantwrite, &sh->dev[i].flags);
+			set_bit(R5_LOCKED, &sh->dev[i].flags);
+			s.locked++;
+		}
+	}
+
+	if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
+	    !sh->reconstruct_state) {
 		struct stripe_head *sh2
 			= get_active_stripe(conf, sh->sector, 1, 1, 1);
 		if (sh2 && test_bit(STRIPE_EXPAND_SOURCE, &sh2->state)) {
@@ -3208,14 +3416,8 @@ static bool handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
 		/* Need to write out all blocks after computing P&Q */
 		sh->disks = conf->raid_disks;
 		stripe_set_idx(sh->sector, conf, 0, sh);
-		compute_parity6(sh, RECONSTRUCT_WRITE);
-		for (i = conf->raid_disks ; i-- ;  ) {
-			set_bit(R5_LOCKED, &sh->dev[i].flags);
-			s.locked++;
-			set_bit(R5_Wantwrite, &sh->dev[i].flags);
-		}
-		clear_bit(STRIPE_EXPANDING, &sh->state);
-	} else if (s.expanded) {
+		schedule_reconstruction(sh, &s, 1, 1);
+	} else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
 		clear_bit(STRIPE_EXPAND_READY, &sh->state);
 		atomic_dec(&conf->reshape_stripes);
 		wake_up(&conf->wait_for_overlap);
@@ -3233,6 +3435,9 @@ static bool handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
 	if (unlikely(blocked_rdev))
 		md_wait_for_blocked_rdev(blocked_rdev, conf->mddev);
 
+	if (s.ops_request)
+		raid_run_ops(sh, s.ops_request);
+
 	ops_run_io(sh, &s);
 
 	return_io(return_bi);
@@ -3241,16 +3446,14 @@ static bool handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
 }
 
 /* returns true if the stripe was handled */
-static bool handle_stripe(struct stripe_head *sh, struct page *tmp_page)
+static bool handle_stripe(struct stripe_head *sh)
 {
 	if (sh->raid_conf->level == 6)
-		return handle_stripe6(sh, tmp_page);
+		return handle_stripe6(sh);
 	else
 		return handle_stripe5(sh);
 }
 
-
-
 static void raid5_activate_delayed(raid5_conf_t *conf)
 {
 	if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
@@ -4046,7 +4249,7 @@ static inline sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *ski
 	spin_unlock(&sh->lock);
 
 	/* wait for any blocked device to be handled */
-	while(unlikely(!handle_stripe(sh, NULL)))
+	while (unlikely(!handle_stripe(sh)))
 		;
 	release_stripe(sh);
 
@@ -4103,7 +4306,7 @@ static int  retry_aligned_read(raid5_conf_t *conf, struct bio *raid_bio)
 			return handled;
 		}
 
-		handle_stripe(sh, NULL);
+		handle_stripe(sh);
 		release_stripe(sh);
 		handled++;
 	}
@@ -4117,6 +4320,36 @@ static int  retry_aligned_read(raid5_conf_t *conf, struct bio *raid_bio)
 	return handled;
 }
 
+#ifdef CONFIG_MULTICORE_RAID456
+static void __process_stripe(void *param, async_cookie_t cookie)
+{
+	struct stripe_head *sh = param;
+
+	handle_stripe(sh);
+	release_stripe(sh);
+}
+
+static void process_stripe(struct stripe_head *sh, struct list_head *domain)
+{
+	async_schedule_domain(__process_stripe, sh, domain);
+}
+
+static void synchronize_stripe_processing(struct list_head *domain)
+{
+	async_synchronize_full_domain(domain);
+}
+#else
+static void process_stripe(struct stripe_head *sh, struct list_head *domain)
+{
+	handle_stripe(sh);
+	release_stripe(sh);
+	cond_resched();
+}
+
+static void synchronize_stripe_processing(struct list_head *domain)
+{
+}
+#endif
 
 
 /*
@@ -4131,6 +4364,7 @@ static void raid5d(mddev_t *mddev)
 	struct stripe_head *sh;
 	raid5_conf_t *conf = mddev_to_conf(mddev);
 	int handled;
+	LIST_HEAD(raid_domain);
 
 	pr_debug("+++ raid5d active\n");
 
@@ -4167,8 +4401,7 @@ static void raid5d(mddev_t *mddev)
 		spin_unlock_irq(&conf->device_lock);
 		
 		handled++;
-		handle_stripe(sh, conf->spare_page);
-		release_stripe(sh);
+		process_stripe(sh, &raid_domain);
 
 		spin_lock_irq(&conf->device_lock);
 	}
@@ -4176,6 +4409,7 @@ static void raid5d(mddev_t *mddev)
 
 	spin_unlock_irq(&conf->device_lock);
 
+	synchronize_stripe_processing(&raid_domain);
 	async_tx_issue_pending_all();
 	unplug_slaves(mddev);
 
@@ -4308,6 +4542,118 @@ raid5_size(mddev_t *mddev, sector_t sectors, int raid_disks)
 	return sectors * (raid_disks - conf->max_degraded);
 }
 
+static void raid5_free_percpu(raid5_conf_t *conf)
+{
+	struct raid5_percpu *percpu;
+	unsigned long cpu;
+
+	if (!conf->percpu)
+		return;
+
+	get_online_cpus();
+	for_each_possible_cpu(cpu) {
+		percpu = per_cpu_ptr(conf->percpu, cpu);
+		safe_put_page(percpu->spare_page);
+		kfree(percpu->scribble);
+	}
+#ifdef CONFIG_HOTPLUG_CPU
+	unregister_cpu_notifier(&conf->cpu_notify);
+#endif
+	put_online_cpus();
+
+	free_percpu(conf->percpu);
+}
+
+static void free_conf(raid5_conf_t *conf)
+{
+	shrink_stripes(conf);
+	raid5_free_percpu(conf);
+	kfree(conf->disks);
+	kfree(conf->stripe_hashtbl);
+	kfree(conf);
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+static int raid456_cpu_notify(struct notifier_block *nfb, unsigned long action,
+			      void *hcpu)
+{
+	raid5_conf_t *conf = container_of(nfb, raid5_conf_t, cpu_notify);
+	long cpu = (long)hcpu;
+	struct raid5_percpu *percpu = per_cpu_ptr(conf->percpu, cpu);
+
+	switch (action) {
+	case CPU_UP_PREPARE:
+	case CPU_UP_PREPARE_FROZEN:
+		if (conf->level == 6 && !percpu->spare_page)
+			percpu->spare_page = alloc_page(GFP_KERNEL);
+		if (!percpu->scribble)
+			percpu->scribble = kmalloc(conf->scribble_len, GFP_KERNEL);
+
+		if (!percpu->scribble ||
+		    (conf->level == 6 && !percpu->spare_page)) {
+			safe_put_page(percpu->spare_page);
+			kfree(percpu->scribble);
+			pr_err("%s: failed memory allocation for cpu%ld\n",
+			       __func__, cpu);
+			return NOTIFY_BAD;
+		}
+		break;
+	case CPU_DEAD:
+	case CPU_DEAD_FROZEN:
+		safe_put_page(percpu->spare_page);
+		kfree(percpu->scribble);
+		percpu->spare_page = NULL;
+		percpu->scribble = NULL;
+		break;
+	default:
+		break;
+	}
+	return NOTIFY_OK;
+}
+#endif
+
+static int raid5_alloc_percpu(raid5_conf_t *conf)
+{
+	unsigned long cpu;
+	struct page *spare_page;
+	struct raid5_percpu *allcpus;
+	void *scribble;
+	int err;
+
+	allcpus = alloc_percpu(struct raid5_percpu);
+	if (!allcpus)
+		return -ENOMEM;
+	conf->percpu = allcpus;
+
+	get_online_cpus();
+	err = 0;
+	for_each_present_cpu(cpu) {
+		if (conf->level == 6) {
+			spare_page = alloc_page(GFP_KERNEL);
+			if (!spare_page) {
+				err = -ENOMEM;
+				break;
+			}
+			per_cpu_ptr(conf->percpu, cpu)->spare_page = spare_page;
+		}
+		scribble = kmalloc(scribble_len(conf->raid_disks), GFP_KERNEL);
+		if (!scribble) {
+			err = -ENOMEM;
+			break;
+		}
+		per_cpu_ptr(conf->percpu, cpu)->scribble = scribble;
+	}
+#ifdef CONFIG_HOTPLUG_CPU
+	conf->cpu_notify.notifier_call = raid456_cpu_notify;
+	conf->cpu_notify.priority = 0;
+	if (err == 0)
+		err = register_cpu_notifier(&conf->cpu_notify);
+#endif
+	put_online_cpus();
+
+	return err;
+}
+
 static raid5_conf_t *setup_conf(mddev_t *mddev)
 {
 	raid5_conf_t *conf;
@@ -4347,6 +4693,7 @@ static raid5_conf_t *setup_conf(mddev_t *mddev)
 		goto abort;
 
 	conf->raid_disks = mddev->raid_disks;
+	conf->scribble_len = scribble_len(conf->raid_disks);
 	if (mddev->reshape_position == MaxSector)
 		conf->previous_raid_disks = mddev->raid_disks;
 	else
@@ -4362,11 +4709,10 @@ static raid5_conf_t *setup_conf(mddev_t *mddev)
 	if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
 		goto abort;
 
-	if (mddev->new_level == 6) {
-		conf->spare_page = alloc_page(GFP_KERNEL);
-		if (!conf->spare_page)
-			goto abort;
-	}
+	conf->level = mddev->new_level;
+	if (raid5_alloc_percpu(conf) != 0)
+		goto abort;
+
 	spin_lock_init(&conf->device_lock);
 	init_waitqueue_head(&conf->wait_for_stripe);
 	init_waitqueue_head(&conf->wait_for_overlap);
@@ -4402,7 +4748,6 @@ static raid5_conf_t *setup_conf(mddev_t *mddev)
 	}
 
 	conf->chunk_size = mddev->new_chunk;
-	conf->level = mddev->new_level;
 	if (conf->level == 6)
 		conf->max_degraded = 2;
 	else
@@ -4437,11 +4782,7 @@ static raid5_conf_t *setup_conf(mddev_t *mddev)
 
  abort:
 	if (conf) {
-		shrink_stripes(conf);
-		safe_put_page(conf->spare_page);
-		kfree(conf->disks);
-		kfree(conf->stripe_hashtbl);
-		kfree(conf);
+		free_conf(conf);
 		return ERR_PTR(-EIO);
 	} else
 		return ERR_PTR(-ENOMEM);
@@ -4607,12 +4948,8 @@ abort:
 	md_unregister_thread(mddev->thread);
 	mddev->thread = NULL;
 	if (conf) {
-		shrink_stripes(conf);
 		print_raid5_conf(conf);
-		safe_put_page(conf->spare_page);
-		kfree(conf->disks);
-		kfree(conf->stripe_hashtbl);
-		kfree(conf);
+		free_conf(conf);
 	}
 	mddev->private = NULL;
 	printk(KERN_ALERT "raid5: failed to run raid set %s\n", mdname(mddev));
@@ -4627,13 +4964,10 @@ static int stop(mddev_t *mddev)
 
 	md_unregister_thread(mddev->thread);
 	mddev->thread = NULL;
-	shrink_stripes(conf);
-	kfree(conf->stripe_hashtbl);
 	mddev->queue->backing_dev_info.congested_fn = NULL;
 	blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
 	sysfs_remove_group(&mddev->kobj, &raid5_attrs_group);
-	kfree(conf->disks);
-	kfree(conf);
+	free_conf(conf);
 	mddev->private = NULL;
 	return 0;
 }
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index 52ba999..116d0b4 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -2,6 +2,7 @@
 #define _RAID5_H
 
 #include <linux/raid/xor.h>
+#include <linux/dmaengine.h>
 
 /*
  *
@@ -175,7 +176,9 @@
  */
 enum check_states {
 	check_state_idle = 0,
-	check_state_run, /* parity check */
+	check_state_run, /* xor parity check */
+	check_state_run_q, /* q-parity check */
+	check_state_run_pq, /* pq dual parity check */
 	check_state_check_result,
 	check_state_compute_run, /* parity repair */
 	check_state_compute_result,
@@ -215,8 +218,8 @@ struct stripe_head {
 	 * @target - STRIPE_OP_COMPUTE_BLK target
 	 */
 	struct stripe_operations {
-		int		   target;
-		u32		   zero_sum_result;
+		int 		     target, target2;
+		enum sum_check_flags zero_sum_result;
 	} ops;
 	struct r5dev {
 		struct bio	req;
@@ -298,7 +301,7 @@ struct r6_state {
 #define STRIPE_OP_COMPUTE_BLK	1
 #define STRIPE_OP_PREXOR	2
 #define STRIPE_OP_BIODRAIN	3
-#define STRIPE_OP_POSTXOR	4
+#define STRIPE_OP_RECONSTRUCT	4
 #define STRIPE_OP_CHECK	5
 
 /*
@@ -383,8 +386,21 @@ struct raid5_private_data {
 					    * (fresh device added).
 					    * Cleared when a sync completes.
 					    */
-
-	struct page 		*spare_page; /* Used when checking P/Q in raid6 */
+	/* per cpu variables */
+	struct raid5_percpu {
+		struct page	*spare_page; /* Used when checking P/Q in raid6 */
+		void		*scribble;   /* space for constructing buffer
+					      * lists and performing address
+					      * conversions
+					      */
+	} *percpu;
+	size_t			scribble_len; /* size of scribble region must be
+					       * associated with conf to handle
+					       * cpu hotplug while reshaping
+					       */
+#ifdef CONFIG_HOTPLUG_CPU
+	struct notifier_block	cpu_notify;
+#endif
 
 	/*
 	 * Free stripes pool
diff --git a/include/linux/async_tx.h b/include/linux/async_tx.h
index 5fc2ef8..866e61c 100644
--- a/include/linux/async_tx.h
+++ b/include/linux/async_tx.h
@@ -58,25 +58,57 @@ struct dma_chan_ref {
  * array.
  * @ASYNC_TX_ACK: immediately ack the descriptor, precludes setting up a
  * dependency chain
- * @ASYNC_TX_DEP_ACK: ack the dependency descriptor.  Useful for chaining.
  */
 enum async_tx_flags {
 	ASYNC_TX_XOR_ZERO_DST	 = (1 << 0),
 	ASYNC_TX_XOR_DROP_DST	 = (1 << 1),
-	ASYNC_TX_ACK		 = (1 << 3),
-	ASYNC_TX_DEP_ACK	 = (1 << 4),
+	ASYNC_TX_ACK		 = (1 << 2),
+};
+
+/**
+ * struct async_submit_ctl - async_tx submission/completion modifiers
+ * @flags: submission modifiers
+ * @depend_tx: parent dependency of the current operation being submitted
+ * @cb_fn: callback routine to run at operation completion
+ * @cb_param: parameter for the callback routine
+ * @scribble: caller provided space for dma/page address conversions
+ */
+struct async_submit_ctl {
+	enum async_tx_flags flags;
+	struct dma_async_tx_descriptor *depend_tx;
+	dma_async_tx_callback cb_fn;
+	void *cb_param;
+	void *scribble;
 };
 
 #ifdef CONFIG_DMA_ENGINE
 #define async_tx_issue_pending_all dma_issue_pending_all
+
+/**
+ * async_tx_issue_pending - send pending descriptor to the hardware channel
+ * @tx: descriptor handle to retrieve hardware context
+ *
+ * Note: any dependent operations will have already been issued by
+ * async_tx_channel_switch, or (in the case of no channel switch) will
+ * be already pending on this channel.
+ */
+static inline void async_tx_issue_pending(struct dma_async_tx_descriptor *tx)
+{
+	if (likely(tx)) {
+		struct dma_chan *chan = tx->chan;
+		struct dma_device *dma = chan->device;
+
+		dma->device_issue_pending(chan);
+	}
+}
 #ifdef CONFIG_ARCH_HAS_ASYNC_TX_FIND_CHANNEL
 #include <asm/async_tx.h>
 #else
 #define async_tx_find_channel(dep, type, dst, dst_count, src, src_count, len) \
 	 __async_tx_find_channel(dep, type)
 struct dma_chan *
-__async_tx_find_channel(struct dma_async_tx_descriptor *depend_tx,
-	enum dma_transaction_type tx_type);
+__async_tx_find_channel(struct async_submit_ctl *submit,
+			enum dma_transaction_type tx_type);
 #endif /* CONFIG_ARCH_HAS_ASYNC_TX_FIND_CHANNEL */
 #else
 static inline void async_tx_issue_pending_all(void)
@@ -84,10 +116,16 @@ static inline void async_tx_issue_pending_all(void)
 	do { } while (0);
 }
 
+static inline void async_tx_issue_pending(struct dma_async_tx_descriptor *tx)
+{
+	do { } while (0);
+}
+
 static inline struct dma_chan *
-async_tx_find_channel(struct dma_async_tx_descriptor *depend_tx,
-	enum dma_transaction_type tx_type, struct page **dst, int dst_count,
-	struct page **src, int src_count, size_t len)
+async_tx_find_channel(struct async_submit_ctl *submit,
+		      enum dma_transaction_type tx_type, struct page **dst,
+		      int dst_count, struct page **src, int src_count,
+		      size_t len)
 {
 	return NULL;
 }
@@ -99,46 +137,70 @@ async_tx_find_channel(struct dma_async_tx_descriptor *depend_tx,
  * @cb_fn_param: parameter to pass to the callback routine
  */
 static inline void
-async_tx_sync_epilog(dma_async_tx_callback cb_fn, void *cb_fn_param)
+async_tx_sync_epilog(struct async_submit_ctl *submit)
 {
-	if (cb_fn)
-		cb_fn(cb_fn_param);
+	if (submit->cb_fn)
+		submit->cb_fn(submit->cb_param);
 }
 
-void
-async_tx_submit(struct dma_chan *chan, struct dma_async_tx_descriptor *tx,
-	enum async_tx_flags flags, struct dma_async_tx_descriptor *depend_tx,
-	dma_async_tx_callback cb_fn, void *cb_fn_param);
+typedef union {
+	unsigned long addr;
+	struct page *page;
+	dma_addr_t dma;
+} addr_conv_t;
+
+static inline void
+init_async_submit(struct async_submit_ctl *args, enum async_tx_flags flags,
+		  struct dma_async_tx_descriptor *tx,
+		  dma_async_tx_callback cb_fn, void *cb_param,
+		  addr_conv_t *scribble)
+{
+	args->flags = flags;
+	args->depend_tx = tx;
+	args->cb_fn = cb_fn;
+	args->cb_param = cb_param;
+	args->scribble = scribble;
+}
+
+void async_tx_submit(struct dma_chan *chan, struct dma_async_tx_descriptor *tx,
+		     struct async_submit_ctl *submit);
 
 struct dma_async_tx_descriptor *
 async_xor(struct page *dest, struct page **src_list, unsigned int offset,
-	int src_cnt, size_t len, enum async_tx_flags flags,
-	struct dma_async_tx_descriptor *depend_tx,
-	dma_async_tx_callback cb_fn, void *cb_fn_param);
+	  int src_cnt, size_t len, struct async_submit_ctl *submit);
 
 struct dma_async_tx_descriptor *
-async_xor_zero_sum(struct page *dest, struct page **src_list,
-	unsigned int offset, int src_cnt, size_t len,
-	u32 *result, enum async_tx_flags flags,
-	struct dma_async_tx_descriptor *depend_tx,
-	dma_async_tx_callback cb_fn, void *cb_fn_param);
+async_xor_val(struct page *dest, struct page **src_list, unsigned int offset,
+	      int src_cnt, size_t len, enum sum_check_flags *result,
+	      struct async_submit_ctl *submit);
 
 struct dma_async_tx_descriptor *
 async_memcpy(struct page *dest, struct page *src, unsigned int dest_offset,
-	unsigned int src_offset, size_t len, enum async_tx_flags flags,
-	struct dma_async_tx_descriptor *depend_tx,
-	dma_async_tx_callback cb_fn, void *cb_fn_param);
+	     unsigned int src_offset, size_t len,
+	     struct async_submit_ctl *submit);
 
 struct dma_async_tx_descriptor *
 async_memset(struct page *dest, int val, unsigned int offset,
-	size_t len, enum async_tx_flags flags,
-	struct dma_async_tx_descriptor *depend_tx,
-	dma_async_tx_callback cb_fn, void *cb_fn_param);
+	     size_t len, struct async_submit_ctl *submit);
+
+struct dma_async_tx_descriptor *async_trigger_callback(struct async_submit_ctl *submit);
+
+struct dma_async_tx_descriptor *
+async_gen_syndrome(struct page **blocks, unsigned int offset, int src_cnt,
+		   size_t len, struct async_submit_ctl *submit);
+
+struct dma_async_tx_descriptor *
+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_trigger_callback(enum async_tx_flags flags,
-	struct dma_async_tx_descriptor *depend_tx,
-	dma_async_tx_callback cb_fn, void *cb_fn_param);
+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_ */
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index ffefba8..1012f1a 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -52,11 +52,11 @@ enum dma_status {
 enum dma_transaction_type {
 	DMA_MEMCPY,
 	DMA_XOR,
-	DMA_PQ_XOR,
+	DMA_PQ,
 	DMA_DUAL_XOR,
 	DMA_PQ_UPDATE,
-	DMA_ZERO_SUM,
-	DMA_PQ_ZERO_SUM,
+	DMA_XOR_VAL,
+	DMA_PQ_VAL,
 	DMA_MEMSET,
 	DMA_MEMCPY_CRC32C,
 	DMA_INTERRUPT,
@@ -70,18 +70,23 @@ enum dma_transaction_type {
 
 /**
  * enum dma_ctrl_flags - DMA flags to augment operation preparation,
- * 	control completion, and communicate status.
+ *  control completion, and communicate status.
  * @DMA_PREP_INTERRUPT - trigger an interrupt (callback) upon completion of
- * 	this transaction
+ *  this transaction
  * @DMA_CTRL_ACK - the descriptor cannot be reused until the client
- * 	acknowledges receipt, i.e. has has a chance to establish any
- * 	dependency chains
+ *  acknowledges receipt, i.e. has has a chance to establish any dependency
+ *  chains
  * @DMA_COMPL_SKIP_SRC_UNMAP - set to disable dma-unmapping the source buffer(s)
  * @DMA_COMPL_SKIP_DEST_UNMAP - set to disable dma-unmapping the destination(s)
  * @DMA_COMPL_SRC_UNMAP_SINGLE - set to do the source dma-unmapping as single
  * 	(if not set, do the source dma-unmapping as page)
  * @DMA_COMPL_DEST_UNMAP_SINGLE - set to do the destination dma-unmapping as single
  * 	(if not set, do the destination dma-unmapping as page)
+ * @DMA_PREP_PQ_DISABLE_P - prevent generation of P while generating Q
+ * @DMA_PREP_PQ_DISABLE_Q - prevent generation of Q while generating P
+ * @DMA_PREP_CONTINUE - indicate to a driver that it is reusing buffers as
+ *  sources that were the result of a previous operation, in the case of a PQ
+ *  operation it continues the calculation with new sources
  */
 enum dma_ctrl_flags {
 	DMA_PREP_INTERRUPT = (1 << 0),
@@ -90,9 +95,31 @@ enum dma_ctrl_flags {
 	DMA_COMPL_SKIP_DEST_UNMAP = (1 << 3),
 	DMA_COMPL_SRC_UNMAP_SINGLE = (1 << 4),
 	DMA_COMPL_DEST_UNMAP_SINGLE = (1 << 5),
+	DMA_PREP_PQ_DISABLE_P = (1 << 6),
+	DMA_PREP_PQ_DISABLE_Q = (1 << 7),
+	DMA_PREP_CONTINUE = (1 << 8),
 };
 
 /**
+ * enum sum_check_bits - bit position of pq_check_flags
+ */
+enum sum_check_bits {
+	SUM_CHECK_P = 0,
+	SUM_CHECK_Q = 1,
+};
+
+/**
+ * enum pq_check_flags - result of async_{xor,pq}_zero_sum operations
+ * @SUM_CHECK_P_RESULT - 1 if xor zero sum error, 0 otherwise
+ * @SUM_CHECK_Q_RESULT - 1 if reed-solomon zero sum error, 0 otherwise
+ */
+enum sum_check_flags {
+	SUM_CHECK_P_RESULT = (1 << SUM_CHECK_P),
+	SUM_CHECK_Q_RESULT = (1 << SUM_CHECK_Q),
+};
+
+
+/**
  * dma_cap_mask_t - capabilities bitmap modeled after cpumask_t.
  * See linux/cpumask.h
  */
@@ -213,6 +240,7 @@ struct dma_async_tx_descriptor {
  * @global_node: list_head for global dma_device_list
  * @cap_mask: one or more dma_capability flags
  * @max_xor: maximum number of xor sources, 0 if no capability
+ * @max_pq: maximum number of PQ sources and PQ-continue capability
  * @dev_id: unique device ID
  * @dev: struct device reference for dma mapping api
  * @device_alloc_chan_resources: allocate resources and return the
@@ -220,7 +248,9 @@ struct dma_async_tx_descriptor {
  * @device_free_chan_resources: release DMA channel's resources
  * @device_prep_dma_memcpy: prepares a memcpy operation
  * @device_prep_dma_xor: prepares a xor operation
- * @device_prep_dma_zero_sum: prepares a zero_sum operation
+ * @device_prep_dma_xor_val: prepares a xor validation operation
+ * @device_prep_dma_pq: prepares a pq operation
+ * @device_prep_dma_pq_val: prepares a pqzero_sum operation
  * @device_prep_dma_memset: prepares a memset operation
  * @device_prep_dma_interrupt: prepares an end of chain interrupt operation
  * @device_prep_slave_sg: prepares a slave dma operation
@@ -235,7 +265,9 @@ struct dma_device {
 	struct list_head channels;
 	struct list_head global_node;
 	dma_cap_mask_t  cap_mask;
-	int max_xor;
+	unsigned short max_xor;
+	unsigned short max_pq;
+	#define DMA_HAS_PQ_CONTINUE (1 << 15)
 
 	int dev_id;
 	struct device *dev;
@@ -249,9 +281,17 @@ struct dma_device {
 	struct dma_async_tx_descriptor *(*device_prep_dma_xor)(
 		struct dma_chan *chan, dma_addr_t dest, dma_addr_t *src,
 		unsigned int src_cnt, size_t len, unsigned long flags);
-	struct dma_async_tx_descriptor *(*device_prep_dma_zero_sum)(
+	struct dma_async_tx_descriptor *(*device_prep_dma_xor_val)(
 		struct dma_chan *chan, dma_addr_t *src,	unsigned int src_cnt,
-		size_t len, u32 *result, unsigned long flags);
+		size_t len, enum sum_check_flags *result, unsigned long flags);
+	struct dma_async_tx_descriptor *(*device_prep_dma_pq)(
+		struct dma_chan *chan, dma_addr_t *dst, dma_addr_t *src,
+		unsigned int src_cnt, const unsigned char *scf,
+		size_t len, unsigned long flags);
+	struct dma_async_tx_descriptor *(*device_prep_dma_pq_val)(
+		struct dma_chan *chan, dma_addr_t *pq, dma_addr_t *src,
+		unsigned int src_cnt, const unsigned char *scf, size_t len,
+		enum sum_check_flags *pqres, unsigned long flags);
 	struct dma_async_tx_descriptor *(*device_prep_dma_memset)(
 		struct dma_chan *chan, dma_addr_t dest, int value, size_t len,
 		unsigned long flags);
@@ -270,6 +310,60 @@ struct dma_device {
 	void (*device_issue_pending)(struct dma_chan *chan);
 };
 
+static inline void
+dma_set_maxpq(struct dma_device *dma, int maxpq, int has_pq_continue)
+{
+	dma->max_pq = maxpq;
+	if (has_pq_continue)
+		dma->max_pq |= DMA_HAS_PQ_CONTINUE;
+}
+
+static inline bool dmaf_continue(enum dma_ctrl_flags flags)
+{
+	return (flags & DMA_PREP_CONTINUE) == DMA_PREP_CONTINUE;
+}
+
+static inline bool dmaf_p_disabled_continue(enum dma_ctrl_flags flags)
+{
+	enum dma_ctrl_flags mask = DMA_PREP_CONTINUE | DMA_PREP_PQ_DISABLE_P;
+
+	return (flags & mask) == mask;
+}
+
+static inline bool dma_dev_has_pq_continue(struct dma_device *dma)
+{
+	return (dma->max_pq & DMA_HAS_PQ_CONTINUE) == DMA_HAS_PQ_CONTINUE;
+}
+
+static unsigned short dma_dev_to_maxpq(struct dma_device *dma)
+{
+	return dma->max_pq & ~DMA_HAS_PQ_CONTINUE;
+}
+
+/* dma_maxpq - reduce maxpq in the face of continued operations
+ * @dma - dma device with PQ capability
+ * @flags - to check if DMA_PREP_CONTINUE and DMA_PREP_PQ_DISABLE_P are set
+ *
+ * When an engine does not support native continuation we need 3 extra
+ * source slots to reuse P and Q with the following coefficients:
+ * 1/ {00} * P : remove P from Q', but use it as a source for P'
+ * 2/ {01} * Q : use Q to continue Q' calculation
+ * 3/ {00} * Q : subtract Q from P' to cancel (2)
+ *
+ * In the case where P is disabled we only need 1 extra source:
+ * 1/ {01} * Q : use Q to continue Q' calculation
+ */
+static inline int dma_maxpq(struct dma_device *dma, enum dma_ctrl_flags flags)
+{
+	if (dma_dev_has_pq_continue(dma) || !dmaf_continue(flags))
+		return dma_dev_to_maxpq(dma);
+	else if (dmaf_p_disabled_continue(flags))
+		return dma_dev_to_maxpq(dma) - 1;
+	else if (dmaf_continue(flags))
+		return dma_dev_to_maxpq(dma) - 3;
+	BUG();
+}
+
 /* --- public DMA engine API --- */
 
 #ifdef CONFIG_DMA_ENGINE