Merge branch 'ioat-md-accel-for-linus' of git://lost.foo-projects.org/~dwillia2/git/iop

* 'ioat-md-accel-for-linus' of git://lost.foo-projects.org/~dwillia2/git/iop: (28 commits)
  ioatdma: add the unisys "i/oat" pci vendor/device id
  ARM: Add drivers/dma to arch/arm/Kconfig
  iop3xx: surface the iop3xx DMA and AAU units to the iop-adma driver
  iop13xx: surface the iop13xx adma units to the iop-adma driver
  dmaengine: driver for the iop32x, iop33x, and iop13xx raid engines
  md: remove raid5 compute_block and compute_parity5
  md: handle_stripe5 - request io processing in raid5_run_ops
  md: handle_stripe5 - add request/completion logic for async expand ops
  md: handle_stripe5 - add request/completion logic for async read ops
  md: handle_stripe5 - add request/completion logic for async check ops
  md: handle_stripe5 - add request/completion logic for async compute ops
  md: handle_stripe5 - add request/completion logic for async write ops
  md: common infrastructure for running operations with raid5_run_ops
  md: raid5_run_ops - run stripe operations outside sh->lock
  raid5: replace custom debug PRINTKs with standard pr_debug
  raid5: refactor handle_stripe5 and handle_stripe6 (v3)
  async_tx: add the async_tx api
  xor: make 'xor_blocks' a library routine for use with async_tx
  dmaengine: make clients responsible for managing channels
  dmaengine: refactor dmaengine around dma_async_tx_descriptor
  ...

5 files changed, 1685 insertions, 1204 deletions

diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index 466909f38d98..64bf3a81db93 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -109,6 +109,8 @@ config MD_RAID10
 config MD_RAID456
 	tristate "RAID-4/RAID-5/RAID-6 mode"
 	depends on BLK_DEV_MD
+	select ASYNC_MEMCPY
+	select ASYNC_XOR
 	---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
diff --git a/drivers/md/Makefile b/drivers/md/Makefile
index 2c45d7683ae9..c49366cdc05d 100644
--- a/drivers/md/Makefile
+++ b/drivers/md/Makefile
@@ -18,7 +18,7 @@ raid456-objs	:= raid5.o raid6algos.o raid6recov.o raid6tables.o \
 hostprogs-y	:= mktables
 
 # Note: link order is important.  All raid personalities
-# and xor.o must come before md.o, as they each initialise 
+# and must come before md.o, as they each initialise 
 # themselves, and md.o may use the personalities when it 
 # auto-initialised.
 
@@ -26,7 +26,7 @@ obj-$(CONFIG_MD_LINEAR)		+= linear.o
 obj-$(CONFIG_MD_RAID0)		+= raid0.o
 obj-$(CONFIG_MD_RAID1)		+= raid1.o
 obj-$(CONFIG_MD_RAID10)		+= raid10.o
-obj-$(CONFIG_MD_RAID456)	+= raid456.o xor.o
+obj-$(CONFIG_MD_RAID456)	+= raid456.o
 obj-$(CONFIG_MD_MULTIPATH)	+= multipath.o
 obj-$(CONFIG_MD_FAULTY)		+= faulty.o
 obj-$(CONFIG_BLK_DEV_MD)	+= md-mod.o
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 1c54f3c1cca7..33beaa7da085 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -5814,7 +5814,7 @@ static __exit void md_exit(void)
 	}
 }
 
-module_init(md_init)
+subsys_initcall(md_init);
 module_exit(md_exit)
 
 static int get_ro(char *buffer, struct kernel_param *kp)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 061375ee6592..0b66afef2d82 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -52,6 +52,7 @@
 #include "raid6.h"
 
 #include <linux/raid/bitmap.h>
+#include <linux/async_tx.h>
 
 /*
  * Stripe cache
@@ -80,7 +81,6 @@
 /*
  * The following can be used to debug the driver
  */
-#define RAID5_DEBUG	0
 #define RAID5_PARANOIA	1
 #if RAID5_PARANOIA && defined(CONFIG_SMP)
 # define CHECK_DEVLOCK() assert_spin_locked(&conf->device_lock)
@@ -88,8 +88,7 @@
 # define CHECK_DEVLOCK()
 #endif
 
-#define PRINTK(x...) ((void)(RAID5_DEBUG && printk(x)))
-#if RAID5_DEBUG
+#ifdef DEBUG
 #define inline
 #define __inline__
 #endif
@@ -104,6 +103,23 @@ static inline int raid6_next_disk(int disk, int raid_disks)
 	disk++;
 	return (disk < raid_disks) ? disk : 0;
 }
+
+static void return_io(struct bio *return_bi)
+{
+	struct bio *bi = return_bi;
+	while (bi) {
+		int bytes = bi->bi_size;
+
+		return_bi = bi->bi_next;
+		bi->bi_next = NULL;
+		bi->bi_size = 0;
+		bi->bi_end_io(bi, bytes,
+			      test_bit(BIO_UPTODATE, &bi->bi_flags)
+			        ? 0 : -EIO);
+		bi = return_bi;
+	}
+}
+
 static void print_raid5_conf (raid5_conf_t *conf);
 
 static void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
@@ -125,6 +141,7 @@ static void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
 			}
 			md_wakeup_thread(conf->mddev->thread);
 		} else {
+			BUG_ON(sh->ops.pending);
 			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)
@@ -152,7 +169,8 @@ static void release_stripe(struct stripe_head *sh)
 
 static inline void remove_hash(struct stripe_head *sh)
 {
-	PRINTK("remove_hash(), stripe %llu\n", (unsigned long long)sh->sector);
+	pr_debug("remove_hash(), stripe %llu\n",
+		(unsigned long long)sh->sector);
 
 	hlist_del_init(&sh->hash);
 }
@@ -161,7 +179,8 @@ static inline void insert_hash(raid5_conf_t *conf, struct stripe_head *sh)
 {
 	struct hlist_head *hp = stripe_hash(conf, sh->sector);
 
-	PRINTK("insert_hash(), stripe %llu\n", (unsigned long long)sh->sector);
+	pr_debug("insert_hash(), stripe %llu\n",
+		(unsigned long long)sh->sector);
 
 	CHECK_DEVLOCK();
 	hlist_add_head(&sh->hash, hp);
@@ -224,9 +243,10 @@ static void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx, int
 
 	BUG_ON(atomic_read(&sh->count) != 0);
 	BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
-	
+	BUG_ON(sh->ops.pending || sh->ops.ack || sh->ops.complete);
+
 	CHECK_DEVLOCK();
-	PRINTK("init_stripe called, stripe %llu\n", 
+	pr_debug("init_stripe called, stripe %llu\n",
 		(unsigned long long)sh->sector);
 
 	remove_hash(sh);
@@ -240,11 +260,11 @@ static void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx, int
 	for (i = sh->disks; i--; ) {
 		struct r5dev *dev = &sh->dev[i];
 
-		if (dev->toread || dev->towrite || dev->written ||
+		if (dev->toread || dev->read || dev->towrite || dev->written ||
 		    test_bit(R5_LOCKED, &dev->flags)) {
-			printk("sector=%llx i=%d %p %p %p %d\n",
+			printk(KERN_ERR "sector=%llx i=%d %p %p %p %p %d\n",
 			       (unsigned long long)sh->sector, i, dev->toread,
-			       dev->towrite, dev->written,
+			       dev->read, dev->towrite, dev->written,
 			       test_bit(R5_LOCKED, &dev->flags));
 			BUG();
 		}
@@ -260,11 +280,11 @@ static struct stripe_head *__find_stripe(raid5_conf_t *conf, sector_t sector, in
 	struct hlist_node *hn;
 
 	CHECK_DEVLOCK();
-	PRINTK("__find_stripe, sector %llu\n", (unsigned long long)sector);
+	pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
 	hlist_for_each_entry(sh, hn, stripe_hash(conf, sector), hash)
 		if (sh->sector == sector && sh->disks == disks)
 			return sh;
-	PRINTK("__stripe %llu not in cache\n", (unsigned long long)sector);
+	pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
 	return NULL;
 }
 
@@ -276,7 +296,7 @@ static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector
 {
 	struct stripe_head *sh;
 
-	PRINTK("get_stripe, sector %llu\n", (unsigned long long)sector);
+	pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
 
 	spin_lock_irq(&conf->device_lock);
 
@@ -324,6 +344,579 @@ static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector
 	return sh;
 }
 
+/* test_and_ack_op() ensures that we only dequeue an operation once */
+#define test_and_ack_op(op, pend) \
+do {							\
+	if (test_bit(op, &sh->ops.pending) &&		\
+		!test_bit(op, &sh->ops.complete)) {	\
+		if (test_and_set_bit(op, &sh->ops.ack)) \
+			clear_bit(op, &pend);		\
+		else					\
+			ack++;				\
+	} else						\
+		clear_bit(op, &pend);			\
+} while (0)
+
+/* find new work to run, do not resubmit work that is already
+ * in flight
+ */
+static unsigned long get_stripe_work(struct stripe_head *sh)
+{
+	unsigned long pending;
+	int ack = 0;
+
+	pending = sh->ops.pending;
+
+	test_and_ack_op(STRIPE_OP_BIOFILL, pending);
+	test_and_ack_op(STRIPE_OP_COMPUTE_BLK, pending);
+	test_and_ack_op(STRIPE_OP_PREXOR, pending);
+	test_and_ack_op(STRIPE_OP_BIODRAIN, pending);
+	test_and_ack_op(STRIPE_OP_POSTXOR, pending);
+	test_and_ack_op(STRIPE_OP_CHECK, pending);
+	if (test_and_clear_bit(STRIPE_OP_IO, &sh->ops.pending))
+		ack++;
+
+	sh->ops.count -= ack;
+	BUG_ON(sh->ops.count < 0);
+
+	return pending;
+}
+
+static int
+raid5_end_read_request(struct bio *bi, unsigned int bytes_done, int error);
+static int
+raid5_end_write_request (struct bio *bi, unsigned int bytes_done, int error);
+
+static void ops_run_io(struct stripe_head *sh)
+{
+	raid5_conf_t *conf = sh->raid_conf;
+	int i, disks = sh->disks;
+
+	might_sleep();
+
+	for (i = disks; i--; ) {
+		int rw;
+		struct bio *bi;
+		mdk_rdev_t *rdev;
+		if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags))
+			rw = WRITE;
+		else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
+			rw = READ;
+		else
+			continue;
+
+		bi = &sh->dev[i].req;
+
+		bi->bi_rw = rw;
+		if (rw == WRITE)
+			bi->bi_end_io = raid5_end_write_request;
+		else
+			bi->bi_end_io = raid5_end_read_request;
+
+		rcu_read_lock();
+		rdev = rcu_dereference(conf->disks[i].rdev);
+		if (rdev && test_bit(Faulty, &rdev->flags))
+			rdev = NULL;
+		if (rdev)
+			atomic_inc(&rdev->nr_pending);
+		rcu_read_unlock();
+
+		if (rdev) {
+			if (test_bit(STRIPE_SYNCING, &sh->state) ||
+				test_bit(STRIPE_EXPAND_SOURCE, &sh->state) ||
+				test_bit(STRIPE_EXPAND_READY, &sh->state))
+				md_sync_acct(rdev->bdev, STRIPE_SECTORS);
+
+			bi->bi_bdev = rdev->bdev;
+			pr_debug("%s: for %llu schedule op %ld on disc %d\n",
+				__FUNCTION__, (unsigned long long)sh->sector,
+				bi->bi_rw, i);
+			atomic_inc(&sh->count);
+			bi->bi_sector = sh->sector + rdev->data_offset;
+			bi->bi_flags = 1 << BIO_UPTODATE;
+			bi->bi_vcnt = 1;
+			bi->bi_max_vecs = 1;
+			bi->bi_idx = 0;
+			bi->bi_io_vec = &sh->dev[i].vec;
+			bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
+			bi->bi_io_vec[0].bv_offset = 0;
+			bi->bi_size = STRIPE_SIZE;
+			bi->bi_next = NULL;
+			if (rw == WRITE &&
+			    test_bit(R5_ReWrite, &sh->dev[i].flags))
+				atomic_add(STRIPE_SECTORS,
+					&rdev->corrected_errors);
+			generic_make_request(bi);
+		} else {
+			if (rw == WRITE)
+				set_bit(STRIPE_DEGRADED, &sh->state);
+			pr_debug("skip op %ld on disc %d for sector %llu\n",
+				bi->bi_rw, i, (unsigned long long)sh->sector);
+			clear_bit(R5_LOCKED, &sh->dev[i].flags);
+			set_bit(STRIPE_HANDLE, &sh->state);
+		}
+	}
+}
+
+static struct dma_async_tx_descriptor *
+async_copy_data(int frombio, struct bio *bio, struct page *page,
+	sector_t sector, struct dma_async_tx_descriptor *tx)
+{
+	struct bio_vec *bvl;
+	struct page *bio_page;
+	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) {
+			b_offset += bio_iovec_idx(bio, i)->bv_offset;
+			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 | ASYNC_TX_KMAP_SRC,
+					tx, NULL, NULL);
+			else
+				tx = async_memcpy(bio_page, page, b_offset,
+					page_offset, clen,
+					ASYNC_TX_DEP_ACK | ASYNC_TX_KMAP_DST,
+					tx, NULL, NULL);
+		}
+		if (clen < len) /* hit end of page */
+			break;
+		page_offset +=  len;
+	}
+
+	return tx;
+}
+
+static void ops_complete_biofill(void *stripe_head_ref)
+{
+	struct stripe_head *sh = stripe_head_ref;
+	struct bio *return_bi = NULL;
+	raid5_conf_t *conf = sh->raid_conf;
+	int i, more_to_read = 0;
+
+	pr_debug("%s: stripe %llu\n", __FUNCTION__,
+		(unsigned long long)sh->sector);
+
+	/* clear completed biofills */
+	for (i = sh->disks; i--; ) {
+		struct r5dev *dev = &sh->dev[i];
+		/* check if this stripe has new incoming reads */
+		if (dev->toread)
+			more_to_read++;
+
+		/* acknowledge completion of a biofill operation */
+		/* and check if we need to reply to a read request
+		*/
+		if (test_bit(R5_Wantfill, &dev->flags) && !dev->toread) {
+			struct bio *rbi, *rbi2;
+			clear_bit(R5_Wantfill, &dev->flags);
+
+			/* The access to dev->read is outside of the
+			 * spin_lock_irq(&conf->device_lock), but is protected
+			 * by the STRIPE_OP_BIOFILL pending bit
+			 */
+			BUG_ON(!dev->read);
+			rbi = dev->read;
+			dev->read = NULL;
+			while (rbi && rbi->bi_sector <
+				dev->sector + STRIPE_SECTORS) {
+				rbi2 = r5_next_bio(rbi, dev->sector);
+				spin_lock_irq(&conf->device_lock);
+				if (--rbi->bi_phys_segments == 0) {
+					rbi->bi_next = return_bi;
+					return_bi = rbi;
+				}
+				spin_unlock_irq(&conf->device_lock);
+				rbi = rbi2;
+			}
+		}
+	}
+	clear_bit(STRIPE_OP_BIOFILL, &sh->ops.ack);
+	clear_bit(STRIPE_OP_BIOFILL, &sh->ops.pending);
+
+	return_io(return_bi);
+
+	if (more_to_read)
+		set_bit(STRIPE_HANDLE, &sh->state);
+	release_stripe(sh);
+}
+
+static void ops_run_biofill(struct stripe_head *sh)
+{
+	struct dma_async_tx_descriptor *tx = NULL;
+	raid5_conf_t *conf = sh->raid_conf;
+	int i;
+
+	pr_debug("%s: stripe %llu\n", __FUNCTION__,
+		(unsigned long long)sh->sector);
+
+	for (i = sh->disks; i--; ) {
+		struct r5dev *dev = &sh->dev[i];
+		if (test_bit(R5_Wantfill, &dev->flags)) {
+			struct bio *rbi;
+			spin_lock_irq(&conf->device_lock);
+			dev->read = rbi = dev->toread;
+			dev->toread = NULL;
+			spin_unlock_irq(&conf->device_lock);
+			while (rbi && rbi->bi_sector <
+				dev->sector + STRIPE_SECTORS) {
+				tx = async_copy_data(0, rbi, dev->page,
+					dev->sector, tx);
+				rbi = r5_next_bio(rbi, dev->sector);
+			}
+		}
+	}
+
+	atomic_inc(&sh->count);
+	async_trigger_callback(ASYNC_TX_DEP_ACK | ASYNC_TX_ACK, tx,
+		ops_complete_biofill, sh);
+}
+
+static void ops_complete_compute5(void *stripe_head_ref)
+{
+	struct stripe_head *sh = stripe_head_ref;
+	int target = sh->ops.target;
+	struct r5dev *tgt = &sh->dev[target];
+
+	pr_debug("%s: stripe %llu\n", __FUNCTION__,
+		(unsigned long long)sh->sector);
+
+	set_bit(R5_UPTODATE, &tgt->flags);
+	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
+	clear_bit(R5_Wantcompute, &tgt->flags);
+	set_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete);
+	set_bit(STRIPE_HANDLE, &sh->state);
+	release_stripe(sh);
+}
+
+static struct dma_async_tx_descriptor *
+ops_run_compute5(struct stripe_head *sh, unsigned long pending)
+{
+	/* kernel stack size limits the total number of disks */
+	int disks = sh->disks;
+	struct page *xor_srcs[disks];
+	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;
+	int i;
+
+	pr_debug("%s: stripe %llu block: %d\n",
+		__FUNCTION__, (unsigned long long)sh->sector, target);
+	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
+
+	for (i = disks; i--; )
+		if (i != target)
+			xor_srcs[count++] = sh->dev[i].page;
+
+	atomic_inc(&sh->count);
+
+	if (unlikely(count == 1))
+		tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE,
+			0, NULL, ops_complete_compute5, sh);
+	else
+		tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
+			ASYNC_TX_XOR_ZERO_DST, NULL,
+			ops_complete_compute5, sh);
+
+	/* ack now if postxor is not set to be run */
+	if (tx && !test_bit(STRIPE_OP_POSTXOR, &pending))
+		async_tx_ack(tx);
+
+	return tx;
+}
+
+static void ops_complete_prexor(void *stripe_head_ref)
+{
+	struct stripe_head *sh = stripe_head_ref;
+
+	pr_debug("%s: stripe %llu\n", __FUNCTION__,
+		(unsigned long long)sh->sector);
+
+	set_bit(STRIPE_OP_PREXOR, &sh->ops.complete);
+}
+
+static struct dma_async_tx_descriptor *
+ops_run_prexor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
+{
+	/* kernel stack size limits the total number of disks */
+	int disks = sh->disks;
+	struct page *xor_srcs[disks];
+	int count = 0, pd_idx = sh->pd_idx, i;
+
+	/* existing parity data subtracted */
+	struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
+
+	pr_debug("%s: stripe %llu\n", __FUNCTION__,
+		(unsigned long long)sh->sector);
+
+	for (i = disks; i--; ) {
+		struct r5dev *dev = &sh->dev[i];
+		/* Only process blocks that are known to be uptodate */
+		if (dev->towrite && test_bit(R5_Wantprexor, &dev->flags))
+			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);
+
+	return tx;
+}
+
+static struct dma_async_tx_descriptor *
+ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
+{
+	int disks = sh->disks;
+	int pd_idx = sh->pd_idx, i;
+
+	/* check if prexor is active which means only process blocks
+	 * that are part of a read-modify-write (Wantprexor)
+	 */
+	int prexor = test_bit(STRIPE_OP_PREXOR, &sh->ops.pending);
+
+	pr_debug("%s: stripe %llu\n", __FUNCTION__,
+		(unsigned long long)sh->sector);
+
+	for (i = disks; i--; ) {
+		struct r5dev *dev = &sh->dev[i];
+		struct bio *chosen;
+		int towrite;
+
+		towrite = 0;
+		if (prexor) { /* rmw */
+			if (dev->towrite &&
+			    test_bit(R5_Wantprexor, &dev->flags))
+				towrite = 1;
+		} else { /* rcw */
+			if (i != pd_idx && dev->towrite &&
+				test_bit(R5_LOCKED, &dev->flags))
+				towrite = 1;
+		}
+
+		if (towrite) {
+			struct bio *wbi;
+
+			spin_lock(&sh->lock);
+			chosen = dev->towrite;
+			dev->towrite = NULL;
+			BUG_ON(dev->written);
+			wbi = dev->written = chosen;
+			spin_unlock(&sh->lock);
+
+			while (wbi && wbi->bi_sector <
+				dev->sector + STRIPE_SECTORS) {
+				tx = async_copy_data(1, wbi, dev->page,
+					dev->sector, tx);
+				wbi = r5_next_bio(wbi, dev->sector);
+			}
+		}
+	}
+
+	return tx;
+}
+
+static void ops_complete_postxor(void *stripe_head_ref)
+{
+	struct stripe_head *sh = stripe_head_ref;
+
+	pr_debug("%s: stripe %llu\n", __FUNCTION__,
+		(unsigned long long)sh->sector);
+
+	set_bit(STRIPE_OP_POSTXOR, &sh->ops.complete);
+	set_bit(STRIPE_HANDLE, &sh->state);
+	release_stripe(sh);
+}
+
+static void ops_complete_write(void *stripe_head_ref)
+{
+	struct stripe_head *sh = stripe_head_ref;
+	int disks = sh->disks, i, pd_idx = sh->pd_idx;
+
+	pr_debug("%s: stripe %llu\n", __FUNCTION__,
+		(unsigned long long)sh->sector);
+
+	for (i = disks; i--; ) {
+		struct r5dev *dev = &sh->dev[i];
+		if (dev->written || i == pd_idx)
+			set_bit(R5_UPTODATE, &dev->flags);
+	}
+
+	set_bit(STRIPE_OP_BIODRAIN, &sh->ops.complete);
+	set_bit(STRIPE_OP_POSTXOR, &sh->ops.complete);
+
+	set_bit(STRIPE_HANDLE, &sh->state);
+	release_stripe(sh);
+}
+
+static void
+ops_run_postxor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
+{
+	/* kernel stack size limits the total number of disks */
+	int disks = sh->disks;
+	struct page *xor_srcs[disks];
+
+	int count = 0, pd_idx = sh->pd_idx, i;
+	struct page *xor_dest;
+	int prexor = test_bit(STRIPE_OP_PREXOR, &sh->ops.pending);
+	unsigned long flags;
+	dma_async_tx_callback callback;
+
+	pr_debug("%s: stripe %llu\n", __FUNCTION__,
+		(unsigned long long)sh->sector);
+
+	/* check if prexor is active which means only process blocks
+	 * that are part of a read-modify-write (written)
+	 */
+	if (prexor) {
+		xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
+		for (i = disks; i--; ) {
+			struct r5dev *dev = &sh->dev[i];
+			if (dev->written)
+				xor_srcs[count++] = dev->page;
+		}
+	} else {
+		xor_dest = sh->dev[pd_idx].page;
+		for (i = disks; i--; ) {
+			struct r5dev *dev = &sh->dev[i];
+			if (i != pd_idx)
+				xor_srcs[count++] = dev->page;
+		}
+	}
+
+	/* check whether this postxor is part of a write */
+	callback = test_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending) ?
+		ops_complete_write : ops_complete_postxor;
+
+	/* 1/ if we prexor'd then the dest is reused as a source
+	 * 2/ if we did not prexor then we are redoing the parity
+	 * 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 |
+		(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, callback, sh);
+	} else
+		tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
+			flags, tx, callback, sh);
+}
+
+static void ops_complete_check(void *stripe_head_ref)
+{
+	struct stripe_head *sh = stripe_head_ref;
+	int pd_idx = sh->pd_idx;
+
+	pr_debug("%s: stripe %llu\n", __FUNCTION__,
+		(unsigned long long)sh->sector);
+
+	if (test_and_clear_bit(STRIPE_OP_MOD_DMA_CHECK, &sh->ops.pending) &&
+		sh->ops.zero_sum_result == 0)
+		set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
+
+	set_bit(STRIPE_OP_CHECK, &sh->ops.complete);
+	set_bit(STRIPE_HANDLE, &sh->state);
+	release_stripe(sh);
+}
+
+static void ops_run_check(struct stripe_head *sh)
+{
+	/* kernel stack size limits the total number of disks */
+	int disks = sh->disks;
+	struct page *xor_srcs[disks];
+	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;
+
+	pr_debug("%s: stripe %llu\n", __FUNCTION__,
+		(unsigned long long)sh->sector);
+
+	for (i = disks; i--; ) {
+		struct r5dev *dev = &sh->dev[i];
+		if (i != pd_idx)
+			xor_srcs[count++] = dev->page;
+	}
+
+	tx = async_xor_zero_sum(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
+		&sh->ops.zero_sum_result, 0, NULL, NULL, NULL);
+
+	if (tx)
+		set_bit(STRIPE_OP_MOD_DMA_CHECK, &sh->ops.pending);
+	else
+		clear_bit(STRIPE_OP_MOD_DMA_CHECK, &sh->ops.pending);
+
+	atomic_inc(&sh->count);
+	tx = async_trigger_callback(ASYNC_TX_DEP_ACK | ASYNC_TX_ACK, tx,
+		ops_complete_check, sh);
+}
+
+static void raid5_run_ops(struct stripe_head *sh, unsigned long pending)
+{
+	int overlap_clear = 0, i, disks = sh->disks;
+	struct dma_async_tx_descriptor *tx = NULL;
+
+	if (test_bit(STRIPE_OP_BIOFILL, &pending)) {
+		ops_run_biofill(sh);
+		overlap_clear++;
+	}
+
+	if (test_bit(STRIPE_OP_COMPUTE_BLK, &pending))
+		tx = ops_run_compute5(sh, pending);
+
+	if (test_bit(STRIPE_OP_PREXOR, &pending))
+		tx = ops_run_prexor(sh, tx);
+
+	if (test_bit(STRIPE_OP_BIODRAIN, &pending)) {
+		tx = ops_run_biodrain(sh, tx);
+		overlap_clear++;
+	}
+
+	if (test_bit(STRIPE_OP_POSTXOR, &pending))
+		ops_run_postxor(sh, tx);
+
+	if (test_bit(STRIPE_OP_CHECK, &pending))
+		ops_run_check(sh);
+
+	if (test_bit(STRIPE_OP_IO, &pending))
+		ops_run_io(sh);
+
+	if (overlap_clear)
+		for (i = disks; i--; ) {
+			struct r5dev *dev = &sh->dev[i];
+			if (test_and_clear_bit(R5_Overlap, &dev->flags))
+				wake_up(&sh->raid_conf->wait_for_overlap);
+		}
+}
+
 static int grow_one_stripe(raid5_conf_t *conf)
 {
 	struct stripe_head *sh;
@@ -537,8 +1130,8 @@ static int raid5_end_read_request(struct bio * bi, unsigned int bytes_done,
 		if (bi == &sh->dev[i].req)
 			break;
 
-	PRINTK("end_read_request %llu/%d, count: %d, uptodate %d.\n", 
-		(unsigned long long)sh->sector, i, atomic_read(&sh->count), 
+	pr_debug("end_read_request %llu/%d, count: %d, uptodate %d.\n",
+		(unsigned long long)sh->sector, i, atomic_read(&sh->count),
 		uptodate);
 	if (i == disks) {
 		BUG();
@@ -613,7 +1206,7 @@ static int raid5_end_write_request (struct bio *bi, unsigned int bytes_done,
 		if (bi == &sh->dev[i].req)
 			break;
 
-	PRINTK("end_write_request %llu/%d, count %d, uptodate: %d.\n", 
+	pr_debug("end_write_request %llu/%d, count %d, uptodate: %d.\n",
 		(unsigned long long)sh->sector, i, atomic_read(&sh->count),
 		uptodate);
 	if (i == disks) {
@@ -658,7 +1251,7 @@ static void error(mddev_t *mddev, mdk_rdev_t *rdev)
 {
 	char b[BDEVNAME_SIZE];
 	raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
-	PRINTK("raid5: error called\n");
+	pr_debug("raid5: error called\n");
 
 	if (!test_bit(Faulty, &rdev->flags)) {
 		set_bit(MD_CHANGE_DEVS, &mddev->flags);
@@ -916,137 +1509,13 @@ static void copy_data(int frombio, struct bio *bio,
 	}
 }
 
-#define check_xor() 	do { 						\
-			   if (count == MAX_XOR_BLOCKS) {		\
-				xor_block(count, STRIPE_SIZE, ptr);	\
-				count = 1;				\
-			   }						\
+#define check_xor()	do {						  \
+				if (count == MAX_XOR_BLOCKS) {		  \
+				xor_blocks(count, STRIPE_SIZE, dest, ptr);\
+				count = 0;				  \
+			   }						  \
 			} while(0)
 
-
-static void compute_block(struct stripe_head *sh, int dd_idx)
-{
-	int i, count, disks = sh->disks;
-	void *ptr[MAX_XOR_BLOCKS], *p;
-
-	PRINTK("compute_block, stripe %llu, idx %d\n", 
-		(unsigned long long)sh->sector, dd_idx);
-
-	ptr[0] = page_address(sh->dev[dd_idx].page);
-	memset(ptr[0], 0, STRIPE_SIZE);
-	count = 1;
-	for (i = disks ; i--; ) {
-		if (i == dd_idx)
-			continue;
-		p = page_address(sh->dev[i].page);
-		if (test_bit(R5_UPTODATE, &sh->dev[i].flags))
-			ptr[count++] = p;
-		else
-			printk(KERN_ERR "compute_block() %d, stripe %llu, %d"
-				" not present\n", dd_idx,
-				(unsigned long long)sh->sector, i);
-
-		check_xor();
-	}
-	if (count != 1)
-		xor_block(count, STRIPE_SIZE, ptr);
-	set_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
-}
-
-static void compute_parity5(struct stripe_head *sh, int method)
-{
-	raid5_conf_t *conf = sh->raid_conf;
-	int i, pd_idx = sh->pd_idx, disks = sh->disks, count;
-	void *ptr[MAX_XOR_BLOCKS];
-	struct bio *chosen;
-
-	PRINTK("compute_parity5, stripe %llu, method %d\n",
-		(unsigned long long)sh->sector, method);
-
-	count = 1;
-	ptr[0] = page_address(sh->dev[pd_idx].page);
-	switch(method) {
-	case READ_MODIFY_WRITE:
-		BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags));
-		for (i=disks ; i-- ;) {
-			if (i==pd_idx)
-				continue;
-			if (sh->dev[i].towrite &&
-			    test_bit(R5_UPTODATE, &sh->dev[i].flags)) {
-				ptr[count++] = page_address(sh->dev[i].page);
-				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;
-				check_xor();
-			}
-		}
-		break;
-	case RECONSTRUCT_WRITE:
-		memset(ptr[0], 0, STRIPE_SIZE);
-		for (i= disks; i-- ;)
-			if (i!=pd_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:
-		break;
-	}
-	if (count>1) {
-		xor_block(count, STRIPE_SIZE, ptr);
-		count = 1;
-	}
-	
-	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);
-		}
-
-	switch(method) {
-	case RECONSTRUCT_WRITE:
-	case CHECK_PARITY:
-		for (i=disks; i--;)
-			if (i != pd_idx) {
-				ptr[count++] = page_address(sh->dev[i].page);
-				check_xor();
-			}
-		break;
-	case READ_MODIFY_WRITE:
-		for (i = disks; i--;)
-			if (sh->dev[i].written) {
-				ptr[count++] = page_address(sh->dev[i].page);
-				check_xor();
-			}
-	}
-	if (count != 1)
-		xor_block(count, STRIPE_SIZE, ptr);
-	
-	if (method != CHECK_PARITY) {
-		set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
-		set_bit(R5_LOCKED,   &sh->dev[pd_idx].flags);
-	} else
-		clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
-}
-
 static void compute_parity6(struct stripe_head *sh, int method)
 {
 	raid6_conf_t *conf = sh->raid_conf;
@@ -1058,7 +1527,7 @@ static void compute_parity6(struct stripe_head *sh, int method)
 	qd_idx = raid6_next_disk(pd_idx, disks);
 	d0_idx = raid6_next_disk(qd_idx, disks);
 
-	PRINTK("compute_parity, stripe %llu, method %d\n",
+	pr_debug("compute_parity, stripe %llu, method %d\n",
 		(unsigned long long)sh->sector, method);
 
 	switch(method) {
@@ -1132,20 +1601,20 @@ static void compute_parity6(struct stripe_head *sh, int method)
 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], *p;
+	void *ptr[MAX_XOR_BLOCKS], *dest, *p;
 	int pd_idx = sh->pd_idx;
 	int qd_idx = raid6_next_disk(pd_idx, disks);
 
-	PRINTK("compute_block_1, stripe %llu, idx %d\n",
+	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 {
-		ptr[0] = page_address(sh->dev[dd_idx].page);
-		if (!nozero) memset(ptr[0], 0, STRIPE_SIZE);
-		count = 1;
+		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;
@@ -1159,8 +1628,8 @@ static void compute_block_1(struct stripe_head *sh, int dd_idx, int nozero)
 
 			check_xor();
 		}
-		if (count != 1)
-			xor_block(count, STRIPE_SIZE, ptr);
+		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);
 	}
@@ -1183,7 +1652,7 @@ static void compute_block_2(struct stripe_head *sh, int dd_idx1, int dd_idx2)
 	BUG_ON(faila == failb);
 	if ( failb < faila ) { int tmp = faila; faila = failb; failb = tmp; }
 
-	PRINTK("compute_block_2, stripe %llu, idx %d,%d (%d,%d)\n",
+	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 == disks-1 ) {
@@ -1229,7 +1698,79 @@ static void compute_block_2(struct stripe_head *sh, int dd_idx1, int dd_idx2)
 	}
 }
 
+static int
+handle_write_operations5(struct stripe_head *sh, int rcw, int expand)
+{
+	int i, pd_idx = sh->pd_idx, disks = sh->disks;
+	int locked = 0;
 
+	if (rcw) {
+		/* if we are not expanding this is a proper write request, and
+		 * there will be bios with new data to be drained into the
+		 * stripe cache
+		 */
+		if (!expand) {
+			set_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending);
+			sh->ops.count++;
+		}
+
+		set_bit(STRIPE_OP_POSTXOR, &sh->ops.pending);
+		sh->ops.count++;
+
+		for (i = disks; i--; ) {
+			struct r5dev *dev = &sh->dev[i];
+
+			if (dev->towrite) {
+				set_bit(R5_LOCKED, &dev->flags);
+				if (!expand)
+					clear_bit(R5_UPTODATE, &dev->flags);
+				locked++;
+			}
+		}
+	} else {
+		BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
+			test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
+
+		set_bit(STRIPE_OP_PREXOR, &sh->ops.pending);
+		set_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending);
+		set_bit(STRIPE_OP_POSTXOR, &sh->ops.pending);
+
+		sh->ops.count += 3;
+
+		for (i = disks; i--; ) {
+			struct r5dev *dev = &sh->dev[i];
+			if (i == pd_idx)
+				continue;
+
+			/* For a read-modify write there may be blocks that are
+			 * locked for reading while others are ready to be
+			 * written so we distinguish these blocks by the
+			 * R5_Wantprexor bit
+			 */
+			if (dev->towrite &&
+			    (test_bit(R5_UPTODATE, &dev->flags) ||
+			    test_bit(R5_Wantcompute, &dev->flags))) {
+				set_bit(R5_Wantprexor, &dev->flags);
+				set_bit(R5_LOCKED, &dev->flags);
+				clear_bit(R5_UPTODATE, &dev->flags);
+				locked++;
+			}
+		}
+	}
+
+	/* keep the parity disk locked while asynchronous operations
+	 * are in flight
+	 */