DLPX-44812 integrate EP-220 large memory scalability

31 files changed, 2294 insertions, 688 deletions

diff --git a/module/zcommon/zfs_fletcher.c b/module/zcommon/zfs_fletcher.c
index 9c2f9c00f..fb0a14991 100644
--- a/module/zcommon/zfs_fletcher.c
+++ b/module/zcommon/zfs_fletcher.c
@@ -28,6 +28,10 @@
  */
 
 /*
+ * Copyright (c) 2016 by Delphix. All rights reserved.
+ */
+
+/*
  * Fletcher Checksums
  * ------------------
  *
@@ -219,14 +223,26 @@ static boolean_t fletcher_4_initialized = B_FALSE;
 
 /*ARGSUSED*/
 void
-fletcher_2_native(const void *buf, uint64_t size,
-    const void *ctx_template, zio_cksum_t *zcp)
+fletcher_init(zio_cksum_t *zcp)
+{
+	ZIO_SET_CHECKSUM(zcp, 0, 0, 0, 0);
+}
+
+int
+fletcher_2_incremental_native(void *buf, size_t size, void *data)
 {
+	zio_cksum_t *zcp = data;
+
 	const uint64_t *ip = buf;
 	const uint64_t *ipend = ip + (size / sizeof (uint64_t));
 	uint64_t a0, b0, a1, b1;
 
-	for (a0 = b0 = a1 = b1 = 0; ip < ipend; ip += 2) {
+	a0 = zcp->zc_word[0];
+	a1 = zcp->zc_word[1];
+	b0 = zcp->zc_word[2];
+	b1 = zcp->zc_word[3];
+
+	for (; ip < ipend; ip += 2) {
 		a0 += ip[0];
 		a1 += ip[1];
 		b0 += a0;
@@ -234,18 +250,33 @@ fletcher_2_native(const void *buf, uint64_t size,
 	}
 
 	ZIO_SET_CHECKSUM(zcp, a0, a1, b0, b1);
+	return (0);
 }
 
 /*ARGSUSED*/
 void
-fletcher_2_byteswap(const void *buf, uint64_t size,
+fletcher_2_native(const void *buf, uint64_t size,
     const void *ctx_template, zio_cksum_t *zcp)
 {
+	fletcher_init(zcp);
+	(void) fletcher_2_incremental_native((void *) buf, size, zcp);
+}
+
+int
+fletcher_2_incremental_byteswap(void *buf, size_t size, void *data)
+{
+	zio_cksum_t *zcp = data;
+
 	const uint64_t *ip = buf;
 	const uint64_t *ipend = ip + (size / sizeof (uint64_t));
 	uint64_t a0, b0, a1, b1;
 
-	for (a0 = b0 = a1 = b1 = 0; ip < ipend; ip += 2) {
+	a0 = zcp->zc_word[0];
+	a1 = zcp->zc_word[1];
+	b0 = zcp->zc_word[2];
+	b1 = zcp->zc_word[3];
+
+	for (; ip < ipend; ip += 2) {
 		a0 += BSWAP_64(ip[0]);
 		a1 += BSWAP_64(ip[1]);
 		b0 += a0;
@@ -253,6 +284,16 @@ fletcher_2_byteswap(const void *buf, uint64_t size,
 	}
 
 	ZIO_SET_CHECKSUM(zcp, a0, a1, b0, b1);
+	return (0);
+}
+
+/*ARGSUSED*/
+void
+fletcher_2_byteswap(const void *buf, uint64_t size,
+    const void *ctx_template, zio_cksum_t *zcp)
+{
+	fletcher_init(zcp);
+	(void) fletcher_2_incremental_byteswap((void *) buf, size, zcp);
 }
 
 static void
@@ -523,25 +564,28 @@ fletcher_4_incremental_impl(boolean_t native, const void *buf, uint64_t size,
 	}
 }
 
-void
-fletcher_4_incremental_native(const void *buf, uint64_t size, zio_cksum_t *zcp)
+int
+fletcher_4_incremental_native(void *buf, size_t size, void *data)
 {
+	zio_cksum_t *zcp = data;
 	/* Use scalar impl to directly update cksum of small blocks */
 	if (size < SPA_MINBLOCKSIZE)
 		fletcher_4_scalar_native((fletcher_4_ctx_t *)zcp, buf, size);
 	else
 		fletcher_4_incremental_impl(B_TRUE, buf, size, zcp);
+	return (0);
 }
 
-void
-fletcher_4_incremental_byteswap(const void *buf, uint64_t size,
-    zio_cksum_t *zcp)
+int
+fletcher_4_incremental_byteswap(void *buf, size_t size, void *data)
 {
+	zio_cksum_t *zcp = data;
 	/* Use scalar impl to directly update cksum of small blocks */
 	if (size < SPA_MINBLOCKSIZE)
 		fletcher_4_scalar_byteswap((fletcher_4_ctx_t *)zcp, buf, size);
 	else
 		fletcher_4_incremental_impl(B_FALSE, buf, size, zcp);
+	return (0);
 }
 
 
@@ -607,6 +651,9 @@ fletcher_4_kstat_addr(kstat_t *ksp, loff_t n)
 
 #define	FLETCHER_4_BENCH_NS	(MSEC2NSEC(50))		/* 50ms */
 
+typedef void fletcher_checksum_func_t(const void *, uint64_t, const void *,
+					zio_cksum_t *);
+
 static void
 fletcher_4_benchmark_impl(boolean_t native, char *data, uint64_t data_size)
 {
@@ -618,8 +665,9 @@ fletcher_4_benchmark_impl(boolean_t native, char *data, uint64_t data_size)
 	zio_cksum_t zc;
 	uint32_t i, l, sel_save = IMPL_READ(fletcher_4_impl_chosen);
 
-	zio_checksum_func_t *fletcher_4_test = native ? fletcher_4_native :
-	    fletcher_4_byteswap;
+
+	fletcher_checksum_func_t *fletcher_4_test = native ?
+	    fletcher_4_native : fletcher_4_byteswap;
 
 	for (i = 0; i < fletcher_4_supp_impls_cnt; i++) {
 		struct fletcher_4_kstat *stat = &fletcher_4_stat_data[i];
@@ -769,6 +817,9 @@ module_param_call(zfs_fletcher_4_impl,
     fletcher_4_param_set, fletcher_4_param_get, NULL, 0644);
 MODULE_PARM_DESC(zfs_fletcher_4_impl, "Select fletcher 4 implementation.");
 
+EXPORT_SYMBOL(fletcher_init);
+EXPORT_SYMBOL(fletcher_2_incremental_native);
+EXPORT_SYMBOL(fletcher_2_incremental_byteswap);
 EXPORT_SYMBOL(fletcher_4_init);
 EXPORT_SYMBOL(fletcher_4_fini);
 EXPORT_SYMBOL(fletcher_2_native);
diff --git a/module/zfs/Makefile.in b/module/zfs/Makefile.in
index 5ad319f32..6712b9b3c 100644
--- a/module/zfs/Makefile.in
+++ b/module/zfs/Makefile.in
@@ -7,6 +7,7 @@ EXTRA_CFLAGS = $(ZFS_MODULE_CFLAGS) @KERNELCPPFLAGS@
 
 obj-$(CONFIG_ZFS) := $(MODULE).o
 
+$(MODULE)-objs += abd.o
 $(MODULE)-objs += arc.o
 $(MODULE)-objs += blkptr.o
 $(MODULE)-objs += bplist.o
diff --git a/module/zfs/abd.c b/module/zfs/abd.c
new file mode 100644
index 000000000..9fa4a5d43
--- /dev/null
+++ b/module/zfs/abd.c
@@ -0,0 +1,1008 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright (c) 2014 by Chunwei Chen. All rights reserved.
+ * Copyright (c) 2016 by Delphix. All rights reserved.
+ */
+
+/*
+ * ARC buffer data (ABD).
+ *
+ * ABDs are an abstract data structure for the ARC which can use two
+ * different ways of storing the underlying data:
+ *
+ * (a) Linear buffer. In this case, all the data in the ABD is stored in one
+ *     contiguous buffer in memory (from a zio_[data_]buf_* kmem cache).
+ *
+ *         +-------------------+
+ *         | ABD (linear)      |
+ *         |   abd_flags = ... |
+ *         |   abd_size = ...  |     +--------------------------------+
+ *         |   abd_buf ------------->| raw buffer of size abd_size    |
+ *         +-------------------+     +--------------------------------+
+ *              no abd_chunks
+ *
+ * (b) Scattered buffer. In this case, the data in the ABD is split into
+ *     equal-sized chunks (from the abd_chunk_cache kmem_cache), with pointers
+ *     to the chunks recorded in an array at the end of the ABD structure.
+ *
+ *         +-------------------+
+ *         | ABD (scattered)   |
+ *         |   abd_flags = ... |
+ *         |   abd_size = ...  |
+ *         |   abd_offset = 0  |                           +-----------+
+ *         |   abd_chunks[0] ----------------------------->| chunk 0   |
+ *         |   abd_chunks[1] ---------------------+        +-----------+
+ *         |   ...             |                  |        +-----------+
+ *         |   abd_chunks[N-1] ---------+         +------->| chunk 1   |
+ *         +-------------------+        |                  +-----------+
+ *                                      |                      ...
+ *                                      |                  +-----------+
+ *                                      +----------------->| chunk N-1 |
+ *                                                         +-----------+
+ *
+ * Linear buffers act exactly like normal buffers and are always mapped into the
+ * kernel's virtual memory space, while scattered ABD data chunks are allocated
+ * as physical pages and then mapped in only while they are actually being
+ * accessed through one of the abd_* library functions. Using scattered ABDs
+ * provides several benefits:
+ *
+ *  (1) They avoid use of kmem_*, preventing performance problems where running
+ *      kmem_reap on very large memory systems never finishes and causes
+ *      constant TLB shootdowns.
+ *
+ *  (2) Fragmentation is less of an issue since when we are at the limit of
+ *      allocatable space, we won't have to search around for a long free
+ *      hole in the VA space for large ARC allocations. Each chunk is mapped in
+ *      individually, so even if we weren't using segkpm (see next point) we
+ *      wouldn't need to worry about finding a contiguous address range.
+ *
+ *  (3) Use of segkpm will avoid the need for map / unmap / TLB shootdown costs
+ *      on each ABD access. (If segkpm isn't available then we use all linear
+ *      ABDs to avoid this penalty.) See seg_kpm.c for more details.
+ *
+ * It is possible to make all ABDs linear by setting zfs_abd_scatter_enabled to
+ * B_FALSE. However, it is not possible to use scattered ABDs if segkpm is not
+ * available, which is the case on all 32-bit systems and any 64-bit systems
+ * where kpm_enable is turned off.
+ *
+ * In addition to directly allocating a linear or scattered ABD, it is also
+ * possible to create an ABD by requesting the "sub-ABD" starting at an offset
+ * within an existing ABD. In linear buffers this is simple (set abd_buf of
+ * the new ABD to the starting point within the original raw buffer), but
+ * scattered ABDs are a little more complex. The new ABD makes a copy of the
+ * relevant abd_chunks pointers (but not the underlying data). However, to
+ * provide arbitrary rather than only chunk-aligned starting offsets, it also
+ * tracks an abd_offset field which represents the starting point of the data
+ * within the first chunk in abd_chunks. For both linear and scattered ABDs,
+ * creating an offset ABD marks the original ABD as the offset's parent, and the
+ * original ABD's abd_children refcount is incremented. This data allows us to
+ * ensure the root ABD isn't deleted before its children.
+ *
+ * Most consumers should never need to know what type of ABD they're using --
+ * the ABD public API ensures that it's possible to transparently switch from
+ * using a linear ABD to a scattered one when doing so would be beneficial.
+ *
+ * If you need to use the data within an ABD directly, if you know it's linear
+ * (because you allocated it) you can use abd_to_buf() to access the underlying
+ * raw buffer. Otherwise, you should use one of the abd_borrow_buf* functions
+ * which will allocate a raw buffer if necessary. Use the abd_return_buf*
+ * functions to return any raw buffers that are no longer necessary when you're
+ * done using them.
+ *
+ * There are a variety of ABD APIs that implement basic buffer operations:
+ * compare, copy, read, write, and fill with zeroes. If you need a custom
+ * function which progressively accesses the whole ABD, use the abd_iterate_*
+ * functions.
+ */
+
+#include <sys/abd.h>
+#include <sys/param.h>
+#include <sys/zio.h>
+#include <sys/zfs_context.h>
+#include <sys/zfs_znode.h>
+
+#ifndef KMC_NOTOUCH
+#define	KMC_NOTOUCH	0
+#endif
+
+typedef struct abd_stats {
+	kstat_named_t abdstat_struct_size;
+	kstat_named_t abdstat_scatter_cnt;
+	kstat_named_t abdstat_scatter_data_size;
+	kstat_named_t abdstat_scatter_chunk_waste;
+	kstat_named_t abdstat_linear_cnt;
+	kstat_named_t abdstat_linear_data_size;
+} abd_stats_t;
+
+static abd_stats_t abd_stats = {
+	/* Amount of memory occupied by all of the abd_t struct allocations */
+	{ "struct_size",			KSTAT_DATA_UINT64 },
+	/*
+	 * The number of scatter ABDs which are currently allocated, excluding
+	 * ABDs which don't own their data (for instance the ones which were
+	 * allocated through abd_get_offset()).
+	 */
+	{ "scatter_cnt",			KSTAT_DATA_UINT64 },
+	/* Amount of data stored in all scatter ABDs tracked by scatter_cnt */
+	{ "scatter_data_size",			KSTAT_DATA_UINT64 },
+	/*
+	 * The amount of space wasted at the end of the last chunk across all
+	 * scatter ABDs tracked by scatter_cnt.
+	 */
+	{ "scatter_chunk_waste",		KSTAT_DATA_UINT64 },
+	/*
+	 * The number of linear ABDs which are currently allocated, excluding
+	 * ABDs which don't own their data (for instance the ones which were
+	 * allocated through abd_get_offset() and abd_get_from_buf()). If an
+	 * ABD takes ownership of its buf then it will become tracked.
+	 */
+	{ "linear_cnt",				KSTAT_DATA_UINT64 },
+	/* Amount of data stored in all linear ABDs tracked by linear_cnt */
+	{ "linear_data_size",			KSTAT_DATA_UINT64 },
+};
+
+#define	ABDSTAT(stat)		(abd_stats.stat.value.ui64)
+#define	ABDSTAT_INCR(stat, val) \
+	atomic_add_64(&abd_stats.stat.value.ui64, (val))
+#define	ABDSTAT_BUMP(stat)	ABDSTAT_INCR(stat, 1)
+#define	ABDSTAT_BUMPDOWN(stat)	ABDSTAT_INCR(stat, -1)
+
+/* see block comment above for description */
+int zfs_abd_scatter_enabled = B_TRUE;
+
+
+#ifdef _KERNEL
+static kstat_t *abd_ksp;
+
+static struct page *
+abd_alloc_chunk(void)
+{
+	struct page *c = alloc_page(kmem_flags_convert(KM_SLEEP));
+	ASSERT3P(c, !=, NULL);
+	return (c);
+}
+
+static void
+abd_free_chunk(struct page *c)
+{
+	__free_pages(c, 0);
+}
+
+static void *
+abd_map_chunk(struct page *c)
+{
+	/*
+	 * Use of segkpm means we don't care if this is mapped S_READ or S_WRITE
+	 * but S_WRITE is conceptually more accurate.
+	 */
+	return (kmap(c));
+}
+
+static void
+abd_unmap_chunk(struct page *c)
+{
+	kunmap(c);
+}
+
+void
+abd_init(void)
+{
+	abd_ksp = kstat_create("zfs", 0, "abdstats", "misc", KSTAT_TYPE_NAMED,
+	    sizeof (abd_stats) / sizeof (kstat_named_t), KSTAT_FLAG_VIRTUAL);
+	if (abd_ksp != NULL) {
+		abd_ksp->ks_data = &abd_stats;
+		kstat_install(abd_ksp);
+	}
+}
+
+void
+abd_fini(void)
+{
+	if (abd_ksp != NULL) {
+		kstat_delete(abd_ksp);
+		abd_ksp = NULL;
+	}
+}
+
+#else
+
+struct page;
+#define	kpm_enable			1
+#define	abd_alloc_chunk() \
+	((struct page *)kmem_alloc(PAGESIZE, KM_SLEEP))
+#define	abd_free_chunk(chunk) 		kmem_free(chunk, PAGESIZE)
+#define	abd_map_chunk(chunk)		((void *)chunk)
+static void
+abd_unmap_chunk(struct page *c)
+{
+}
+
+void
+abd_init(void)
+{
+}
+
+void
+abd_fini(void)
+{
+}
+
+#endif /* _KERNEL */
+
+static inline size_t
+abd_chunkcnt_for_bytes(size_t size)
+{
+	return (P2ROUNDUP(size, PAGESIZE) / PAGESIZE);
+}
+
+static inline size_t
+abd_scatter_chunkcnt(abd_t *abd)
+{
+	ASSERT(!abd_is_linear(abd));
+	return (abd_chunkcnt_for_bytes(
+	    abd->abd_u.abd_scatter.abd_offset + abd->abd_size));
+}
+
+static inline void
+abd_verify(abd_t *abd)
+{
+	ASSERT3U(abd->abd_size, >, 0);
+	ASSERT3U(abd->abd_size, <=, SPA_MAXBLOCKSIZE);
+	ASSERT3U(abd->abd_flags, ==, abd->abd_flags & (ABD_FLAG_LINEAR |
+	    ABD_FLAG_OWNER | ABD_FLAG_META));
+	IMPLY(abd->abd_parent != NULL, !(abd->abd_flags & ABD_FLAG_OWNER));
+	IMPLY(abd->abd_flags & ABD_FLAG_META, abd->abd_flags & ABD_FLAG_OWNER);
+	if (abd_is_linear(abd)) {
+		ASSERT3P(abd->abd_u.abd_linear.abd_buf, !=, NULL);
+	} else {
+		size_t n;
+		int i;
+
+		ASSERT3U(abd->abd_u.abd_scatter.abd_offset, <, PAGESIZE);
+		n = abd_scatter_chunkcnt(abd);
+		for (i = 0; i < n; i++) {
+			ASSERT3P(
+			    abd->abd_u.abd_scatter.abd_chunks[i], !=, NULL);
+		}
+	}
+}
+
+static inline abd_t *
+abd_alloc_struct(size_t chunkcnt)
+{
+	size_t size = offsetof(abd_t, abd_u.abd_scatter.abd_chunks[chunkcnt]);
+	abd_t *abd = kmem_alloc(size, KM_PUSHPAGE);
+	ASSERT3P(abd, !=, NULL);
+	ABDSTAT_INCR(abdstat_struct_size, size);
+
+	return (abd);
+}
+
+static inline void
+abd_free_struct(abd_t *abd)
+{
+	size_t chunkcnt = abd_is_linear(abd) ? 0 : abd_scatter_chunkcnt(abd);
+	int size = offsetof(abd_t, abd_u.abd_scatter.abd_chunks[chunkcnt]);
+	kmem_free(abd, size);
+	ABDSTAT_INCR(abdstat_struct_size, -size);
+}
+
+/*
+ * Allocate an ABD, along with its own underlying data buffers. Use this if you
+ * don't care whether the ABD is linear or not.
+ */
+abd_t *
+abd_alloc(size_t size, boolean_t is_metadata)
+{
+	int i;
+	size_t n;
+	abd_t *abd;
+
+	if (!zfs_abd_scatter_enabled)
+		return (abd_alloc_linear(size, is_metadata));
+
+	VERIFY3U(size, <=, SPA_MAXBLOCKSIZE);
+
+	n = abd_chunkcnt_for_bytes(size);
+	abd = abd_alloc_struct(n);
+
+	abd->abd_flags = ABD_FLAG_OWNER;
+	if (is_metadata) {
+		abd->abd_flags |= ABD_FLAG_META;
+	}
+	abd->abd_size = size;
+	abd->abd_parent = NULL;
+	refcount_create(&abd->abd_children);
+
+	abd->abd_u.abd_scatter.abd_offset = 0;
+	abd->abd_u.abd_scatter.abd_chunk_size = PAGESIZE;
+
+	for (i = 0; i < n; i++) {
+		void *c = abd_alloc_chunk();
+		ASSERT3P(c, !=, NULL);
+		abd->abd_u.abd_scatter.abd_chunks[i] = c;
+	}
+
+	ABDSTAT_BUMP(abdstat_scatter_cnt);
+	ABDSTAT_INCR(abdstat_scatter_data_size, size);
+	ABDSTAT_INCR(abdstat_scatter_chunk_waste,
+	    n * PAGESIZE - size);
+
+	return (abd);
+}
+
+static void
+abd_free_scatter(abd_t *abd)
+{
+	size_t n = abd_scatter_chunkcnt(abd);
+	int i;
+
+	for (i = 0; i < n; i++) {
+		abd_free_chunk(abd->abd_u.abd_scatter.abd_chunks[i]);
+	}
+
+	refcount_destroy(&abd->abd_children);
+	ABDSTAT_BUMPDOWN(abdstat_scatter_cnt);
+	ABDSTAT_INCR(abdstat_scatter_data_size, -(int)abd->abd_size);
+	ABDSTAT_INCR(abdstat_scatter_chunk_waste,
+	    abd->abd_size - n * PAGESIZE);
+
+	abd_free_struct(abd);
+}
+
+/*
+ * Allocate an ABD that must be linear, along with its own underlying data
+ * buffer. Only use this when it would be very annoying to write your ABD
+ * consumer with a scattered ABD.
+ */
+abd_t *
+abd_alloc_linear(size_t size, boolean_t is_metadata)
+{
+	abd_t *abd = abd_alloc_struct(0);
+
+	VERIFY3U(size, <=, SPA_MAXBLOCKSIZE);
+
+	abd->abd_flags = ABD_FLAG_LINEAR | ABD_FLAG_OWNER;
+	if (is_metadata) {
+		abd->abd_flags |= ABD_FLAG_META;
+	}
+	abd->abd_size = size;
+	abd->abd_parent = NULL;
+	refcount_create(&abd->abd_children);
+
+	if (is_metadata) {
+		abd->abd_u.abd_linear.abd_buf = zio_buf_alloc(size);
+	} else {
+		abd->abd_u.abd_linear.abd_buf = zio_data_buf_alloc(size);
+	}
+
+	ABDSTAT_BUMP(abdstat_linear_cnt);
+	ABDSTAT_INCR(abdstat_linear_data_size, size);
+
+	return (abd);
+}
+
+static void
+abd_free_linear(abd_t *abd)
+{
+	if (abd->abd_flags & ABD_FLAG_META) {
+		zio_buf_free(abd->abd_u.abd_linear.abd_buf, abd->abd_size);
+	} else {
+		zio_data_buf_free(abd->abd_u.abd_linear.abd_buf, abd->abd_size);
+	}
+
+	refcount_destroy(&abd->abd_children);
+	ABDSTAT_BUMPDOWN(abdstat_linear_cnt);
+	ABDSTAT_INCR(abdstat_linear_data_size, -(int)abd->abd_size);
+
+	abd_free_struct(abd);
+}
+
+/*
+ * Free an ABD. Only use this on ABDs allocated with abd_alloc() or
+ * abd_alloc_linear().
+ */
+void
+abd_free(abd_t *abd)
+{
+	abd_verify(abd);
+	ASSERT3P(abd->abd_parent, ==, NULL);
+	ASSERT(abd->abd_flags & ABD_FLAG_OWNER);
+	if (abd_is_linear(abd))
+		abd_free_linear(abd);
+	else
+		abd_free_scatter(abd);
+}
+
+/*
+ * Allocate an ABD of the same format (same metadata flag, same scatterize
+ * setting) as another ABD.
+ */
+abd_t *
+abd_alloc_sametype(abd_t *sabd, size_t size)
+{
+	boolean_t is_metadata = (sabd->abd_flags | ABD_FLAG_META) != 0;
+	if (abd_is_linear(sabd)) {
+		return (abd_alloc_linear(size, is_metadata));
+	} else {
+		return (abd_alloc(size, is_metadata));
+	}
+}
+
+/*
+ * If we're going to use this ABD for doing I/O using the block layer, the
+ * consumer of the ABD data doesn't care if it's scattered or not, and we don't
+ * plan to store this ABD in memory for a long period of time, we should
+ * allocate the ABD type that requires the least data copying to do the I/O.
+ *
+ * On Illumos this is linear ABDs, however if ldi_strategy() can ever issue I/Os
+ * using a scatter/gather list we should switch to that and replace this call
+ * with vanilla abd_alloc().
+ *
+ * On Linux the optimal thing to do would be to use abd_get_offset() and
+ * construct a new ABD which shares the original pages thereby eliminating
+ * the copy.  But for the moment a new linear ABD is allocated until this
+ * performance optimization can be implemented.
+ */
+abd_t *
+abd_alloc_for_io(size_t size, boolean_t is_metadata)
+{
+	return (abd_alloc_linear(size, is_metadata));
+}
+
+/*
+ * Allocate a new ABD to point to offset off of sabd. It shares the underlying
+ * buffer data with sabd. Use abd_put() to free. sabd must not be freed while
+ * any derived ABDs exist.
+ */
+abd_t *
+abd_get_offset(abd_t *sabd, size_t off)
+{
+	abd_t *abd;
+
+	abd_verify(sabd);
+	ASSERT3U(off, <=, sabd->abd_size);
+
+	if (abd_is_linear(sabd)) {
+		abd = abd_alloc_struct(0);
+
+		/*
+		 * Even if this buf is filesystem metadata, we only track that
+		 * if we own the underlying data buffer, which is not true in
+		 * this case. Therefore, we don't ever use ABD_FLAG_META here.
+		 */
+		abd->abd_flags = ABD_FLAG_LINEAR;
+
+		abd->abd_u.abd_linear.abd_buf =
+		    (char *)sabd->abd_u.abd_linear.abd_buf + off;
+	} else {
+		size_t new_offset = sabd->abd_u.abd_scatter.abd_offset + off;
+		size_t chunkcnt = abd_scatter_chunkcnt(sabd) -
+		    (new_offset / PAGESIZE);
+
+		abd = abd_alloc_struct(chunkcnt);
+
+		/*
+		 * Even if this buf is filesystem metadata, we only track that
+		 * if we own the underlying data buffer, which is not true in
+		 * this case. Therefore, we don't ever use ABD_FLAG_META here.
+		 */
+		abd->abd_flags = 0;
+
+		abd->abd_u.abd_scatter.abd_offset = new_offset % PAGESIZE;
+		abd->abd_u.abd_scatter.abd_chunk_size = PAGESIZE;
+
+		/* Copy the scatterlist starting at the correct offset */
+		(void) memcpy(&abd->abd_u.abd_scatter.abd_chunks,
+		    &sabd->abd_u.abd_scatter.abd_chunks[new_offset / PAGESIZE],
+		    chunkcnt * sizeof (void *));
+	}
+
+	abd->abd_size = sabd->abd_size - off;
+	abd->abd_parent = sabd;
+	refcount_create(&abd->abd_children);
+	(void) refcount_add_many(&sabd->abd_children, abd->abd_size, abd);
+
+	return (abd);
+}
+
+/*
+ * Allocate a linear ABD structure for buf. You must free this with abd_put()
+ * since the resulting ABD doesn't own its own buffer.
+ */
+abd_t *
+abd_get_from_buf(void *buf, size_t size)
+{
+	abd_t *abd = abd_alloc_struct(0);
+
+	VERIFY3U(size, <=, SPA_MAXBLOCKSIZE);
+
+	/*
+	 * Even if this buf is filesystem metadata, we only track that if we
+	 * own the underlying data buffer, which is not true in this case.
+	 * Therefore, we don't ever use ABD_FLAG_META here.
+	 */
+	abd->abd_flags = ABD_FLAG_LINEAR;
+	abd->abd_size = size;
+	abd->abd_parent = NULL;
+	refcount_create(&abd->abd_children);
+
+	abd->abd_u.abd_linear.abd_buf = buf;
+
+	return (abd);
+}
+
+/*
+ * Free an ABD allocated from abd_get_offset() or abd_get_from_buf(). Will not
+ * free the underlying scatterlist or buffer.
+ */
+void
+abd_put(abd_t *abd)
+{
+	abd_verify(abd);
+	ASSERT(!(abd->abd_flags & ABD_FLAG_OWNER));
+
+	if (abd->abd_parent != NULL) {
+		(void) refcount_remove_many(&abd->abd_parent->abd_children,
+		    abd->abd_size, abd);
+	}
+
+	refcount_destroy(&abd->abd_children);
+	abd_free_struct(abd);
+}
+
+/*
+ * Get the raw buffer associated with a linear ABD.
+ */
+void *
+abd_to_buf(abd_t *abd)
+{
+	ASSERT(abd_is_linear(abd));
+	abd_verify(abd);
+	return (abd->abd_u.abd_linear.abd_buf);
+}
+
+/*
+ * Borrow a raw buffer from an ABD without copying the contents of the ABD
+ * into the buffer. If the ABD is scattered, this will allocate a raw buffer
+ * whose contents are undefined. To copy over the existing data in the ABD, use
+ * abd_borrow_buf_copy() instead.
+ */
+void *
+abd_borrow_buf(abd_t *abd, size_t n)
+{
+	void *buf;
+	abd_verify(abd);
+	ASSERT3U(abd->abd_size, >=, n);
+	if (abd_is_linear(abd)) {
+		buf = abd_to_buf(abd);
+	} else {
+		buf = zio_buf_alloc(n);
+	}
+	(void) refcount_add_many(&abd->abd_children, n, buf);
+
+	return (buf);
+}
+
+void *
+abd_borrow_buf_copy(abd_t *abd, size_t n)
+{
+	void *buf = abd_borrow_buf(abd, n);
+	if (!abd_is_linear(abd)) {
+		abd_copy_to_buf(buf, abd, n);
+	}
+	return (buf);
+}
+
+/*
+ * Return a borrowed raw buffer to an ABD. If the ABD is scattered, this will
+ * not change the contents of the ABD and will ASSERT that you didn't modify
+ * the buffer since it was borrowed. If you want any changes you made to buf to
+ * be copied back to abd, use abd_return_buf_copy() instead.
+ */
+void
+abd_return_buf(abd_t *abd, void *buf, size_t n)
+{
+	abd_verify(abd);
+	ASSERT3U(abd->abd_size, >=, n);
+	if (abd_is_linear(abd)) {
+		ASSERT3P(buf, ==, abd_to_buf(abd));
+	} else {
+		ASSERT0(abd_cmp_buf(abd, buf, n));
+		zio_buf_free(buf, n);
+	}
+	(void) refcount_remove_many(&abd->abd_children, n, buf);
+}
+
+void
+abd_return_buf_copy(abd_t *abd, void *buf, size_t n)
+{
+	if (!abd_is_linear(abd)) {
+		abd_copy_from_buf(abd, buf, n);
+	}
+	abd_return_buf(abd, buf, n);
+}
+
+/*
+ * Give this ABD ownership of the buffer that it's storing. Can only be used on
+ * linear ABDs which were allocated via abd_get_from_buf(), or ones allocated
+ * with abd_alloc_linear() which subsequently released ownership of their buf
+ * with abd_release_ownership_of_buf().
+ */
+void
+abd_take_ownership_of_buf(abd_t *abd, boolean_t is_metadata)
+{
+	ASSERT(abd_is_linear(abd));
+	ASSERT(!(abd->abd_flags & ABD_FLAG_OWNER));
+	abd_verify(abd);
+
+	abd->abd_flags |= ABD_FLAG_OWNER;
+	if (is_metadata) {
+		abd->abd_flags |= ABD_FLAG_META;
+	}
+
+	ABDSTAT_BUMP(abdstat_linear_cnt);
+	ABDSTAT_INCR(abdstat_linear_data_size, abd->abd_size);
+}
+
+void
+abd_release_ownership_of_buf(abd_t *abd)
+{
+	ASSERT(abd_is_linear(abd));
+	ASSERT(abd->abd_flags & ABD_FLAG_OWNER);
+	abd_verify(abd);
+
+	abd->abd_flags &= ~ABD_FLAG_OWNER;
+	/* Disable this flag since we no longer own the data buffer */
+	abd->abd_flags &= ~ABD_FLAG_META;
+
+	ABDSTAT_BUMPDOWN(abdstat_linear_cnt);
+	ABDSTAT_INCR(abdstat_linear_data_size, -(int)abd->abd_size);
+}
+
+struct abd_iter {
+	abd_t		*iter_abd;	/* ABD being iterated through */
+	size_t		iter_pos;	/* position (relative to abd_offset) */
+	void		*iter_mapaddr;	/* addr corresponding to iter_pos */
+	size_t		iter_mapsize;	/* length of data valid at mapaddr */
+};
+
+static inline size_t
+abd_iter_scatter_chunk_offset(struct abd_iter *aiter)
+{
+	ASSERT(!abd_is_linear(aiter->iter_abd));
+	return ((aiter->iter_abd->abd_u.abd_scatter.abd_offset +
+	    aiter->iter_pos) % PAGESIZE);
+}
+
+static inline size_t
+abd_iter_scatter_chunk_index(struct abd_iter *aiter)
+{
+	ASSERT(!abd_is_linear(aiter->iter_abd));
+	return ((aiter->iter_abd->abd_u.abd_scatter.abd_offset +
+	    aiter->iter_pos) / PAGESIZE);
+}
+
+/*
+ * Initialize the abd_iter.
+ */
+static void
+abd_iter_init(struct abd_iter *aiter, abd_t *abd)
+{
+	abd_verify(abd);
+	aiter->iter_abd = abd;
+	aiter->iter_pos = 0;
+	aiter->iter_mapaddr = NULL;
+	aiter->iter_mapsize = 0;
+}
+
+/*
+ * Advance the iterator by a certain amount. Cannot be called when a chunk is
+ * in use. This can be safely called when the aiter has already exhausted, in
+ * which case this does nothing.
+ */
+static void
+abd_iter_advance(struct abd_iter *aiter, size_t amount)
+{
+	ASSERT3P(aiter->iter_mapaddr, ==, NULL);
+	ASSERT0(aiter->iter_mapsize);
+
+	/* There's nothing left to advance to, so do nothing */
+	if (aiter->iter_pos == aiter->iter_abd->abd_size)
+		return;
+
+	aiter->iter_pos += amount;
+}
+
+/*
+ * Map the current chunk into aiter. This can be safely called when the aiter
+ * has already exhausted, in which case this does nothing.
+ */
+static void
+abd_iter_map(struct abd_iter *aiter)
+{
+	void *paddr;
+	size_t offset = 0;
+
+	ASSERT3P(aiter->iter_mapaddr, ==, NULL);
+	ASSERT0(aiter->iter_mapsize);
+
+	/* There's nothing left to iterate over, so do nothing */
+	if (aiter->iter_pos == aiter->iter_abd->abd_size)
+		return;
+
+	if (abd_is_linear(aiter->iter_abd)) {
+		offset = aiter->iter_pos;
+		aiter->iter_mapsize = aiter->iter_abd->abd_size - offset;
+		paddr = aiter->iter_abd->abd_u.abd_linear.abd_buf;
+	} else {
+		size_t index = abd_iter_scatter_chunk_index(aiter);
+		offset = abd_iter_scatter_chunk_offset(aiter);
+		aiter->iter_mapsize = PAGESIZE - offset;
+		paddr = abd_map_chunk(
+			aiter->iter_abd->abd_u.abd_scatter.abd_chunks[index]);
+	}
+	aiter->iter_mapaddr = (char *)paddr + offset;
+}
+
+/*
+ * Unmap the current chunk from aiter. This can be safely called when the aiter
+ * has already exhausted, in which case this does nothing.
+ */
+static void
+abd_iter_unmap(struct abd_iter *aiter)
+{
+	/* There's nothing left to unmap, so do nothing */
+	if (aiter->iter_pos == aiter->iter_abd->abd_size)
+		return;
+
+	if (!abd_is_linear(aiter->iter_abd)) {
+		/* LINTED E_FUNC_SET_NOT_USED */
+		size_t index = abd_iter_scatter_chunk_index(aiter);
+		abd_unmap_chunk(
+		    aiter->iter_abd->abd_u.abd_scatter.abd_chunks[index]);
+	}
+
+	ASSERT3P(aiter->iter_mapaddr, !=, NULL);
+	ASSERT3U(aiter->iter_mapsize, >, 0);
+
+	aiter->iter_mapaddr = NULL;
+	aiter->iter_mapsize = 0;
+}
+
+int
+abd_iterate_func(abd_t *abd, size_t off, size_t size,
+    abd_iter_func_t *func, void *private)
+{
+	int ret = 0;
+	struct abd_iter aiter;
+
+	abd_verify(abd);
+	ASSERT3U(off + size, <=, abd->abd_size);
+
+	abd_iter_init(&aiter, abd);
+	abd_iter_advance(&aiter, off);
+
+	while (size > 0) {
+		size_t len;
+		abd_iter_map(&aiter);
+
+		len = MIN(aiter.iter_mapsize, size);
+		ASSERT3U(len, >, 0);
+
+		ret = func(aiter.iter_mapaddr, len, private);
+
+		abd_iter_unmap(&aiter);
+
+		if (ret != 0)
+			break;
+
+		size -= len;
+		abd_iter_advance(&aiter, len);
+	}
+
+	return (ret);
+}
+
+struct buf_arg {
+	void *arg_buf;
+};
+
+static int
+abd_copy_to_buf_off_cb(void *buf, size_t size, void *private)
+{
+	struct buf_arg *ba_ptr = private;
+
+	(void) memcpy(ba_ptr->arg_buf, buf, size);
+	ba_ptr->arg_buf = (char *)ba_ptr->arg_buf + size;
+
+	return (0);
+}
+
+/*
+ * Copy abd to buf. (off is the offset in abd.)
+ */
+void
+abd_copy_to_buf_off(void *buf, abd_t *abd, size_t off, size_t size)
+{
+	struct buf_arg ba_ptr = { buf };
+
+	(void) abd_iterate_func(abd, off, size, abd_copy_to_buf_off_cb,
+	    &ba_ptr);
+}
+
+static int
+abd_cmp_buf_off_cb(void *buf, size_t size, void *private)
+{
+	int ret;
+	struct buf_arg *ba_ptr = private;
+
+	ret = memcmp(buf, ba_ptr->arg_buf, size);
+	ba_ptr->arg_buf = (char *)ba_ptr->arg_buf + size;
+
+	return (ret);
+}
+
+/*
+ * Compare the contents of abd to buf. (off is the offset in abd.)
+ */
+int
+abd_cmp_buf_off(abd_t *abd, const void *buf, size_t off, size_t size)
+{
+	struct buf_arg ba_ptr = { (void *) buf };
+
+	return (abd_iterate_func(abd, off, size, abd_cmp_buf_off_cb, &ba_ptr));
+}
+
+static int
+abd_copy_from_buf_off_cb(void *buf, size_t size, void *private)
+{
+	struct buf_arg *ba_ptr = private;
+
+	(void) memcpy(buf, ba_ptr->arg_buf, size);
+	ba_ptr->arg_buf = (char *)ba_ptr->arg_buf + size;
+
+	return (0);
+}
+
+/*
+ * Copy from buf to abd. (off is the offset in abd.)
+ */
+void
+abd_copy_from_buf_off(abd_t *abd, const void *buf, size_t off, size_t size)
+{
+	struct buf_arg ba_ptr = { (void *) buf };
+
+	(void) abd_iterate_func(abd, off, size, abd_copy_from_buf_off_cb,
+	    &ba_ptr);
+}
+
+/*ARGSUSED*/
+static int
+abd_zero_off_cb(void *buf, size_t size, void *private)
+{
+	(void) memset(buf, 0, size);
+	return (0);
+}
+
+/*
+ * Zero out the abd from a particular offset to the end.
+ */
+void
+abd_zero_off(abd_t *abd, size_t off, size_t size)
+{
+	(void) abd_iterate_func(abd, off, size, abd_zero_off_cb, NULL);
+}
+
+/*
+ * Iterate over two ABDs and call func incrementally on the two ABDs' data in
+ * equal-sized chunks (passed to func as raw buffers). func could be called many
+ * times during this iteration.
+ */
+int
+abd_iterate_func2(abd_t *dabd, abd_t *sabd, size_t doff, size_t soff,
+    size_t size, abd_iter_func2_t *func, void *private)
+{
+	int ret = 0;
+	struct abd_iter daiter, saiter;
+
+	abd_verify(dabd);
+	abd_verify(sabd);
+
+	ASSERT3U(doff + size, <=, dabd->abd_size);
+	ASSERT3U(soff + size, <=, sabd->abd_size);
+
+	abd_iter_init(&daiter, dabd);
+	abd_iter_init(&saiter, sabd);
+	abd_iter_advance(&daiter, doff);
+	abd_iter_advance(&saiter, soff);
+
+	while (size > 0) {
+		size_t dlen, slen, len;
+		abd_iter_map(&daiter);
+		abd_iter_map(&saiter);
+
+		dlen = MIN(daiter.iter_mapsize, size);
+		slen = MIN(saiter.iter_mapsize, size);
+		len = MIN(dlen, slen);
+		ASSERT(dlen > 0 || slen > 0);
+
+		ret = func(daiter.iter_mapaddr, saiter.iter_mapaddr, len,
+		    private);
+
+		abd_iter_unmap(&saiter);
+		abd_iter_unmap(&daiter);
+
+		if (ret != 0)
+			break;
+
+		size -= len;
+		abd_iter_advance(&daiter, len);
+		abd_iter_advance(&saiter, len);
+	}
+
+	return (ret);
+}
+
+/*ARGSUSED*/
+static int
+abd_copy_off_cb(void *dbuf, void *sbuf, size_t size, void *private)
+{
+	(void) memcpy(dbuf, sbuf, size);
+	return (0);
+}
+
+/*
+ * Copy from sabd to dabd starting from soff and doff.
+ */
+void
+abd_copy_off(abd_t *dabd, abd_t *sabd, size_t doff, size_t soff, size_t size)
+{
+	(void) abd_iterate_func2(dabd, sabd, doff, soff, size,
+	    abd_copy_off_cb, NULL);
+}
+
+/*ARGSUSED*/
+static int
+abd_cmp_cb(void *bufa, void *bufb, size_t size, void *private)
+{
+	return (memcmp(bufa, bufb, size));
+}
+
+/*
+ * Compares the contents of two ABDs.
+ */
+int
+abd_cmp(abd_t *dabd, abd_t *sabd)
+{
+	ASSERT3U(dabd->abd_size, ==, sabd->abd_size);
+	return (abd_iterate_func2(dabd, sabd, 0, 0, dabd->abd_size,
+	    abd_cmp_cb, NULL));
+}
+
+
+#if defined(_KERNEL) && defined(HAVE_SPL)
+/* Tunable Parameters */
+module_param(zfs_abd_scatter_enabled, int, 0644);
+MODULE_PARM_DESC(zfs_abd_scatter_enabled,
+	"Toggle whether ABD allocations must be linear.");
+#endif
diff --git a/module/zfs/arc.c b/module/zfs/arc.c
index e3e933044..e54a7cc59 100644
--- a/module/zfs/arc.c
+++ b/module/zfs/arc.c
@@ -136,14 +136,14 @@
  * the arc_buf_hdr_t that will point to the data block in memory. A block can
  * only be read by a consumer if it has an l1arc_buf_hdr_t. The L1ARC
  * caches data in two ways -- in a list of ARC buffers (arc_buf_t) and
- * also in the arc_buf_hdr_t's private physical data block pointer (b_pdata).
+ * also in the arc_buf_hdr_t's private physical data block pointer (b_pabd).
  *
  * The L1ARC's data pointer may or may not be uncompressed. The ARC has the
- * ability to store the physical data (b_pdata) associated with the DVA of the
- * arc_buf_hdr_t. Since the b_pdata is a copy of the on-disk physical block,
+ * ability to store the physical data (b_pabd) associated with the DVA of the
+ * arc_buf_hdr_t. Since the b_pabd is a copy of the on-disk physical block,
  * it will match its on-disk compression characteristics. This behavior can be
  * disabled by setting 'zfs_compressed_arc_enabled' to B_FALSE. When the
- * compressed ARC functionality is disabled, the b_pdata will point to an
+ * compressed ARC functionality is disabled, the b_pabd will point to an
  * uncompressed version of the on-disk data.
  *
  * Data in the L1ARC is not accessed by consumers of the ARC directly. Each
@@ -182,7 +182,7 @@
  *   | l1arc_buf_hdr_t
  *   |           |              arc_buf_t
  *   | b_buf     +------------>+-----------+      arc_buf_t
- *   | b_pdata   +-+           |b_next     +---->+-----------+
+ *   | b_pabd    +-+           |b_next     +---->+-----------+
  *   +-----------+ |           |-----------|     |b_next     +-->NULL
  *                 |           |b_comp = T |     +-----------+
  *                 |           |b_data     +-+   |b_comp = F |
@@ -199,8 +199,8 @@
  * When a consumer reads a block, the ARC must first look to see if the
  * arc_buf_hdr_t is cached. If the hdr is cached then the ARC allocates a new
  * arc_buf_t and either copies uncompressed data into a new data buffer from an
- * existing uncompressed arc_buf_t, decompresses the hdr's b_pdata buffer into a
- * new data buffer, or shares the hdr's b_pdata buffer, depending on whether the
+ * existing uncompressed arc_buf_t, decompresses the hdr's b_pabd buffer into a
+ * new data buffer, or shares the hdr's b_pabd buffer, depending on whether the
  * hdr is compressed and the desired compression characteristics of the
  * arc_buf_t consumer. If the arc_buf_t ends up sharing data with the
  * arc_buf_hdr_t and both of them are uncompressed then the arc_buf_t must be
@@ -224,7 +224,7 @@
  *                |           |                 arc_buf_t    (shared)
  *                |    b_buf  +------------>+---------+      arc_buf_t
  *                |           |             |b_next   +---->+---------+
- *                |  b_pdata  +-+           |---------|     |b_next   +-->NULL
+ *                |  b_pabd   +-+           |---------|     |b_next   +-->NULL
  *                +-----------+ |           |         |     +---------+
  *                              |           |b_data   +-+   |         |
  *                              |           +---------+ |   |b_data   +-+
@@ -238,19 +238,19 @@
  *                                    |                    +------+     |
  *                                    +---------------------------------+
  *
- * Writing to the ARC requires that the ARC first discard the hdr's b_pdata
+ * Writing to the ARC requires that the ARC first discard the hdr's b_pabd
  * since the physical block is about to be rewritten. The new data contents
  * will be contained in the arc_buf_t. As the I/O pipeline performs the write,
  * it may compress the data before writing it to disk. The ARC will be called
  * with the transformed data and will bcopy the transformed on-disk block into
- * a newly allocated b_pdata. Writes are always done into buffers which have
+ * a newly allocated b_pabd. Writes are always done into buffers which have
  * either been loaned (and hence are new and don't have other readers) or
  * buffers which have been released (and hence have their own hdr, if there
  * were originally other readers of the buf's original hdr). This ensures that
  * the ARC only needs to update a single buf and its hdr after a write occurs.
  *
- * When the L2ARC is in use, it will also take advantage of the b_pdata. The
- * L2ARC will always write the contents of b_pdata to the L2ARC. This means
+ * When the L2ARC is in use, it will also take advantage of the b_pabd. The
+ * L2ARC will always write the contents of b_pabd to the L2ARC. This means
  * that when compressed ARC is enabled that the L2ARC blocks are identical
  * to the on-disk block in the main data pool. This provides a significant
  * advantage since the ARC can leverage the bp's checksum when reading from the
@@ -271,7 +271,9 @@
 #include <sys/vdev.h>
 #include <sys/vdev_impl.h>
 #include <sys/dsl_pool.h>
+#include <sys/zio_checksum.h>
 #include <sys/multilist.h>
+#include <sys/abd.h>
 #ifdef _KERNEL
 #include <sys/vmsystm.h>
 #include <vm/anon.h>
@@ -315,7 +317,7 @@ int zfs_arc_num_sublists_per_state = 0;
 /* number of seconds before growing cache again */
 static int		arc_grow_retry = 5;
 
-/* shift of arc_c for calculating overflow limit in arc_get_data_buf */
+/* shift of arc_c for calculating overflow limit in arc_get_data_impl */
 int		zfs_arc_overflow_shift = 8;
 
 /* shift of arc_c for calculating both min and max arc_p */
@@ -455,13 +457,13 @@ typedef struct arc_stats {
 	kstat_named_t arcstat_c_max;
 	kstat_named_t arcstat_size;
 	/*
-	 * Number of compressed bytes stored in the arc_buf_hdr_t's b_pdata.
+	 * Number of compressed bytes stored in the arc_buf_hdr_t's b_pabd.
 	 * Note that the compressed bytes may match the uncompressed bytes
 	 * if the block is either not compressed or compressed arc is disabled.
 	 */
 	kstat_named_t arcstat_compressed_size;
 	/*
-	 * Uncompressed size of the data stored in b_pdata. If compressed
+	 * Uncompressed size of the data stored in b_pabd. If compressed
 	 * arc is disabled then this value will be identical to the stat
 	 * above.
 	 */
@@ -960,7 +962,7 @@ typedef struct l2arc_read_callback {
 
 typedef struct l2arc_data_free {
 	/* protected by l2arc_free_on_write_mtx */
-	void		*l2df_data;
+	abd_t		*l2df_abd;
 	size_t		l2df_size;
 	arc_buf_contents_t l2df_type;
 	list_node_t	l2df_list_node;
@@ -970,10 +972,14 @@ static kmutex_t l2arc_feed_thr_lock;
 static kcondvar_t l2arc_feed_thr_cv;
 static uint8_t l2arc_thread_exit;
 
+static abd_t *arc_get_data_abd(arc_buf_hdr_t *, uint64_t, void *);
 static void *arc_get_data_buf(arc_buf_hdr_t *, uint64_t, void *);
+static void arc_get_data_impl(arc_buf_hdr_t *, uint64_t, void *);
+static void arc_free_data_abd(arc_buf_hdr_t *, abd_t *, uint64_t, void *);
 static void arc_free_data_buf(arc_buf_hdr_t *, void *, uint64_t, void *);
-static void arc_hdr_free_pdata(arc_buf_hdr_t *hdr);
-static void arc_hdr_alloc_pdata(arc_buf_hdr_t *);
+static void arc_free_data_impl(arc_buf_hdr_t *hdr, uint64_t size, void *tag);
+static void arc_hdr_free_pabd(arc_buf_hdr_t *);
+static void arc_hdr_alloc_pabd(arc_buf_hdr_t *);
 static void arc_access(arc_buf_hdr_t *, kmutex_t *);
 static boolean_t arc_is_overflowing(void);
 static void arc_buf_watch(arc_buf_t *);
@@ -1336,7 +1342,9 @@ static inline boolean_t
 arc_buf_is_shared(arc_buf_t *buf)
 {
 	boolean_t shared = (buf->b_data != NULL &&
-	    buf->b_data == buf->b_hdr->b_l1hdr.b_pdata);
+	    buf->b_hdr->b_l1hdr.b_pabd != NULL &&
+	    abd_is_linear(buf->b_hdr->b_l1hdr.b_pabd) &&
+	    buf->b_data == abd_to_buf(buf->b_hdr->b_l1hdr.b_pabd));
 	IMPLY(shared, HDR_SHARED_DATA(buf->b_hdr));
 	IMPLY(shared, ARC_BUF_SHARED(buf));
 	IMPLY(shared, ARC_BUF_COMPRESSED(buf) || ARC_BUF_LAST(buf));
@@ -1376,8 +1384,6 @@ arc_cksum_verify(arc_buf_t *buf)
 		return;
 
 	if (ARC_BUF_COMPRESSED(buf)) {
-		ASSERT(hdr->b_l1hdr.b_freeze_cksum == NULL ||
-		    hdr->b_l1hdr.b_bufcnt > 1);
 		return;
 	}
 
@@ -1424,7 +1430,8 @@ arc_cksum_is_equal(arc_buf_hdr_t *hdr, zio_t *zio)
 
 		cbuf = zio_buf_alloc(HDR_GET_PSIZE(hdr));
 		lsize = HDR_GET_LSIZE(hdr);
-		csize = zio_compress_data(compress, zio->io_data, cbuf, lsize);
+		csize = zio_compress_data(compress, zio->io_abd, cbuf, lsize);
+
 		ASSERT3U(csize, <=, HDR_GET_PSIZE(hdr));
 		if (csize < HDR_GET_PSIZE(hdr)) {
 			/*
@@ -1459,7 +1466,7 @@ arc_cksum_is_equal(arc_buf_hdr_t *hdr, zio_t *zio)
 	 * logical I/O size and not just a gang fragment.
 	 */
 	valid_cksum = (zio_checksum_error_impl(zio->io_spa, zio->io_bp,
-	    BP_GET_CHECKSUM(zio->io_bp), zio->io_data, zio->io_size,
+	    BP_GET_CHECKSUM(zio->io_bp), zio->io_abd, zio->io_size,
 	    zio->io_offset, NULL) == 0);
 	zio_pop_transforms(zio);
 	return (valid_cksum);
@@ -1483,18 +1490,9 @@ arc_cksum_compute(arc_buf_t *buf)
 
 	mutex_enter(&buf->b_hdr->b_l1hdr.b_freeze_lock);
 	if (hdr->b_l1hdr.b_freeze_cksum != NULL) {
-		ASSERT(!ARC_BUF_COMPRESSED(buf) || hdr->b_l1hdr.b_bufcnt > 1);
 		mutex_exit(&hdr->b_l1hdr.b_freeze_lock);
 		return;
 	} else if (ARC_BUF_COMPRESSED(buf)) {
-		/*
-		 * Since the checksum doesn't apply to compressed buffers, we
-		 * only keep a checksum if there are uncompressed buffers.
-		 * Therefore there must be another buffer, which is
-		 * uncompressed.
-		 */
-		IMPLY(hdr->b_l1hdr.b_freeze_cksum != NULL,
-		    hdr->b_l1hdr.b_bufcnt > 1);
 		mutex_exit(&hdr->b_l1hdr.b_freeze_lock);
 		return;
 	}
@@ -1589,8 +1587,6 @@ arc_buf_thaw(arc_buf_t *buf)
 	 * allocate b_thawed.
 	 */
 	if (ARC_BUF_COMPRESSED(buf)) {
-		ASSERT(hdr->b_l1hdr.b_freeze_cksum == NULL ||
-		    hdr->b_l1hdr.b_bufcnt > 1);
 		return;
 	}
 
@@ -1609,8 +1605,6 @@ arc_buf_freeze(arc_buf_t *buf)
 		return;
 
 	if (ARC_BUF_COMPRESSED(buf)) {
-		ASSERT(hdr->b_l1hdr.b_freeze_cksum == NULL ||
-		    hdr->b_l1hdr.b_bufcnt > 1);
 		return;
 	}
 
@@ -1740,7 +1734,7 @@ arc_buf_fill(arc_buf_t *buf, boolean_t compressed)
 
 	if (hdr_compressed == compressed) {
 		if (!arc_buf_is_shared(buf)) {
-			bcopy(hdr->b_l1hdr.b_pdata, buf->b_data,
+			abd_copy_to_buf(buf->b_data, hdr->b_l1hdr.b_pabd,
 			    arc_buf_size(buf));
 		}
 	} else {
@@ -1792,7 +1786,7 @@ arc_buf_fill(arc_buf_t *buf, boolean_t compressed)
 			return (0);
 		} else {
 			int error = zio_decompress_data(HDR_GET_COMPRESS(hdr),
-			    hdr->b_l1hdr.b_pdata, buf->b_data,
+			    hdr->b_l1hdr.b_pabd, buf->b_data,
 			    HDR_GET_PSIZE(hdr), HDR_GET_LSIZE(hdr));
 
 			/*
@@ -1829,7 +1823,7 @@ arc_decompress(arc_buf_t *buf)
 }
 
 /*
- * Return the size of the block, b_pdata, that is stored in the arc_buf_hdr_t.
+ * Return the size of the block, b_pabd, that is stored in the arc_buf_hdr_t.
  */
 static uint64_t
 arc_hdr_size(arc_buf_hdr_t *hdr)
@@ -1862,14 +1856,14 @@ arc_evictable_space_increment(arc_buf_hdr_t *hdr, arc_state_t *state)
 	if (GHOST_STATE(state)) {
 		ASSERT0(hdr->b_l1hdr.b_bufcnt);
 		ASSERT3P(hdr->b_l1hdr.b_buf, ==, NULL);
-		ASSERT3P(hdr->b_l1hdr.b_pdata, ==, NULL);
+		ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
 		(void) refcount_add_many(&state->arcs_esize[type],
 		    HDR_GET_LSIZE(hdr), hdr);
 		return;
 	}
 
 	ASSERT(!GHOST_STATE(state));
-	if (hdr->b_l1hdr.b_pdata != NULL) {
+	if (hdr->b_l1hdr.b_pabd != NULL) {
 		(void) refcount_add_many(&state->arcs_esize[type],
 		    arc_hdr_size(hdr), hdr);
 	}
@@ -1897,14 +1891,14 @@ arc_evictable_space_decrement(arc_buf_hdr_t *hdr, arc_state_t *state)
 	if (GHOST_STATE(state)) {
 		ASSERT0(hdr->b_l1hdr.b_bufcnt);
 		ASSERT3P(hdr->b_l1hdr.b_buf, ==, NULL);
-		ASSERT3P(hdr->b_l1hdr.b_pdata, ==, NULL);
+		ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
 		(void) refcount_remove_many(&state->arcs_esize[type],
 		    HDR_GET_LSIZE(hdr), hdr);
 		return;
 	}
 
 	ASSERT(!GHOST_STATE(state));
-	if (hdr->b_l1hdr.b_pdata != NULL) {
+	if (hdr->b_l1hdr.b_pabd != NULL) {
 		(void) refcount_remove_many(&state->arcs_esize[type],
 		    arc_hdr_size(hdr), hdr);
 	}
@@ -2051,7 +2045,7 @@ arc_change_state(arc_state_t *new_state, arc_buf_hdr_t *hdr,
 		old_state = hdr->b_l1hdr.b_state;
 		refcnt = refcount_count(&hdr->b_l1hdr.b_refcnt);
 		bufcnt = hdr->b_l1hdr.b_bufcnt;
-		update_old = (bufcnt > 0 || hdr->b_l1hdr.b_pdata != NULL);
+		update_old = (bufcnt > 0 || hdr->b_l1hdr.b_pabd != NULL);
 	} else {
 		old_state = arc_l2c_only;
 		refcnt = 0;
@@ -2120,7 +2114,7 @@ arc_change_state(arc_state_t *new_state, arc_buf_hdr_t *hdr,
 			 */
 			(void) refcount_add_many(&new_state->arcs_size,
 			    HDR_GET_LSIZE(hdr), hdr);
-			ASSERT3P(hdr->b_l1hdr.b_pdata, ==, NULL);
+			ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
 		} else {
 			arc_buf_t *buf;
 			uint32_t buffers = 0;
@@ -2150,7 +2144,7 @@ arc_change_state(arc_state_t *new_state, arc_buf_hdr_t *hdr,
 			}
 			ASSERT3U(bufcnt, ==, buffers);
 
-			if (hdr->b_l1hdr.b_pdata != NULL) {
+			if (hdr->b_l1hdr.b_pabd != NULL) {
 				(void) refcount_add_many(&new_state->arcs_size,
 				    arc_hdr_size(hdr), hdr);
 			} else {
@@ -2163,7 +2157,7 @@ arc_change_state(arc_state_t *new_state, arc_buf_hdr_t *hdr,
 		ASSERT(HDR_HAS_L1HDR(hdr));
 		if (GHOST_STATE(old_state)) {
 			ASSERT0(bufcnt);
-			ASSERT3P(hdr->b_l1hdr.b_pdata, ==, NULL);
+			ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
 
 			/*
 			 * When moving a header off of a ghost state,
@@ -2204,7 +2198,7 @@ arc_change_state(arc_state_t *new_state, arc_buf_hdr_t *hdr,
 				    buf);
 			}
 			ASSERT3U(bufcnt, ==, buffers);
-			ASSERT3P(hdr->b_l1hdr.b_pdata, !=, NULL);
+			ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
 			(void) refcount_remove_many(
 			    &old_state->arcs_size, arc_hdr_size(hdr), hdr);
 		}
@@ -2302,7 +2296,7 @@ arc_space_return(uint64_t space, arc_space_type_t type)
 
 /*
  * Given a hdr and a buf, returns whether that buf can share its b_data buffer
- * with the hdr's b_pdata.
+ * with the hdr's b_pabd.
  */
 static boolean_t
 arc_can_share(arc_buf_hdr_t *hdr, arc_buf_t *buf)
@@ -2397,17 +2391,20 @@ arc_buf_alloc_impl(arc_buf_hdr_t *hdr, void *tag, boolean_t compressed,
 	 * set the appropriate bit in the hdr's b_flags to indicate the hdr is
 	 * allocate a new buffer to store the buf's data.
 	 *
-	 * There is one additional restriction here because we're sharing
-	 * hdr -> buf instead of the usual buf -> hdr: the hdr can't be actively
-	 * involved in an L2ARC write, because if this buf is used by an
-	 * arc_write() then the hdr's data buffer will be released when the
+	 * There are two additional restrictions here because we're sharing
+	 * hdr -> buf instead of the usual buf -> hdr. First, the hdr can't be
+	 * actively involved in an L2ARC write, because if this buf is used by
+	 * an arc_write() then the hdr's data buffer will be released when the
 	 * write completes, even though the L2ARC write might still be using it.
+	 * Second, the hdr's ABD must be linear so that the buf's user doesn't
+	 * need to be ABD-aware.
 	 */
-	can_share = arc_can_share(hdr, buf) && !HDR_L2_WRITING(hdr);
+	can_share = arc_can_share(hdr, buf) && !HDR_L2_WRITING(hdr) &&
+	    abd_is_linear(hdr->b_l1hdr.b_pabd);
 
 	/* Set up b_data and sharing */
 	if (can_share) {
-		buf->b_data = hdr->b_l1hdr.b_pdata;
+		buf->b_data = abd_to_buf(hdr->b_l1hdr.b_pabd);
 		buf->b_flags |= ARC_BUF_FLAG_SHARED;
 		arc_hdr_set_flags(hdr, ARC_FLAG_SHARED_DATA);
 	} else {
@@ -2492,11 +2489,11 @@ arc_loan_inuse_buf(arc_buf_t *buf, void *tag)
 }
 
 static void
-l2arc_free_data_on_write(void *data, size_t size, arc_buf_contents_t type)
+l2arc_free_abd_on_write(abd_t *abd, size_t size, arc_buf_contents_t type)
 {
 	l2arc_data_free_t *df = kmem_alloc(sizeof (*df), KM_SLEEP);
 
-	df->l2df_data = data;
+	df->l2df_abd = abd;
 	df->l2df_size = size;
 	df->l2df_type = type;
 	mutex_enter(&l2arc_free_on_write_mtx);
@@ -2521,7 +2518,7 @@ arc_hdr_free_on_write(arc_buf_hdr_t *hdr)
 	}
 	(void) refcount_remove_many(&state->arcs_size, size, hdr);
 
-	l2arc_free_data_on_write(hdr->b_l1hdr.b_pdata, size, type);
+	l2arc_free_abd_on_write(hdr->b_l1hdr.b_pabd, size, type);
 }
 
 /*
@@ -2533,7 +2530,7 @@ static void
 arc_share_buf(arc_buf_hdr_t *hdr, arc_buf_t *buf)
 {
 	ASSERT(arc_can_share(hdr, buf));
-	ASSERT3P(hdr->b_l1hdr.b_pdata, ==, NULL);
+	ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
 	ASSERT(MUTEX_HELD(HDR_LOCK(hdr)) || HDR_EMPTY(hdr));
 
 	/*
@@ -2542,7 +2539,9 @@ arc_share_buf(arc_buf_hdr_t *hdr, arc_buf_t *buf)
 	 * the refcount whenever an arc_buf_t is shared.
 	 */
 	refcount_transfer_ownership(&hdr->b_l1hdr.b_state->arcs_size, buf, hdr);
-	hdr->b_l1hdr.b_pdata = buf->b_data;
+	hdr->b_l1hdr.b_pabd = abd_get_from_buf(buf->b_data, arc_buf_size(buf));
+	abd_take_ownership_of_buf(hdr->b_l1hdr.b_pabd,
+	    HDR_ISTYPE_METADATA(hdr));
 	arc_hdr_set_flags(hdr, ARC_FLAG_SHARED_DATA);
 	buf->b_flags |= ARC_BUF_FLAG_SHARED;
 
@@ -2560,7 +2559,7 @@ static void
 arc_unshare_buf(arc_buf_hdr_t *hdr, arc_buf_t *buf)
 {
 	ASSERT(arc_buf_is_shared(buf));
-	ASSERT3P(hdr->b_l1hdr.b_pdata, !=, NULL);
+	ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
 	ASSERT(MUTEX_HELD(HDR_LOCK(hdr)) || HDR_EMPTY(hdr));
 
 	/*
@@ -2569,7 +2568,9 @@ arc_unshare_buf(arc_buf_hdr_t *hdr, arc_buf_t *buf)
 	 */
 	refcount_transfer_ownership(&hdr->b_l1hdr.b_state->arcs_size, hdr, buf);
 	arc_hdr_clear_flags(hdr, ARC_FLAG_SHARED_DATA);
-	hdr->b_l1hdr.b_pdata = NULL;
+	abd_release_ownership_of_buf(hdr->b_l1hdr.b_pabd);
+	abd_put(hdr->b_l1hdr.b_pabd);
+	hdr->b_l1hdr.b_pabd = NULL;
 	buf->b_flags &= ~ARC_BUF_FLAG_SHARED;
 
 	/*
@@ -2665,7 +2666,7 @@ arc_buf_destroy_impl(arc_buf_t *buf)
 	if (ARC_BUF_SHARED(buf) && !ARC_BUF_COMPRESSED(buf)) {
 		/*
 		 * If the current arc_buf_t is sharing its data buffer with the
-		 * hdr, then reassign the hdr's b_pdata to share it with the new
+		 * hdr, then reassign the hdr's b_pabd to share it with the new
 		 * buffer at the end of the list. The shared buffer is always
 		 * the last one on the hdr's buffer list.
 		 *
@@ -2680,8 +2681,8 @@ arc_buf_destroy_impl(arc_buf_t *buf)
 			/* hdr is uncompressed so can't have compressed buf */
 			VERIFY(!ARC_BUF_COMPRESSED(lastbuf));
 
-			ASSERT3P(hdr->b_l1hdr.b_pdata, !=, NULL);
-			arc_hdr_free_pdata(hdr);
+			ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
+			arc_hdr_free_pabd(hdr);
 
 			/*
 			 * We must setup a new shared block between the
@@ -2714,26 +2715,26 @@ arc_buf_destroy_impl(arc_buf_t *buf)
 }
 
 static void
-arc_hdr_alloc_pdata(arc_buf_hdr_t *hdr)
+arc_hdr_alloc_pabd(arc_buf_hdr_t *hdr)
 {
 	ASSERT3U(HDR_GET_LSIZE(hdr), >, 0);
 	ASSERT(HDR_HAS_L1HDR(hdr));
 	ASSERT(!HDR_SHARED_DATA(hdr));
 
-	ASSERT3P(hdr->b_l1hdr.b_pdata, ==, NULL);
-	hdr->b_l1hdr.b_pdata = arc_get_data_buf(hdr, arc_hdr_size(hdr), hdr);
+	ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
+	hdr->b_l1hdr.b_pabd = arc_get_data_abd(hdr, arc_hdr_size(hdr), hdr);
 	hdr->b_l1hdr.b_byteswap = DMU_BSWAP_NUMFUNCS;
-	ASSERT3P(hdr->b_l1hdr.b_pdata, !=, NULL);
+	ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
 
 	ARCSTAT_INCR(arcstat_compressed_size, arc_hdr_size(hdr));
 	ARCSTAT_INCR(arcstat_uncompressed_size, HDR_GET_LSIZE(hdr));
 }
 
 static void
-arc_hdr_free_pdata(arc_buf_hdr_t *hdr)
+arc_hdr_free_pabd(arc_buf_hdr_t *hdr)
 {
 	ASSERT(HDR_HAS_L1HDR(hdr));
-	ASSERT3P(hdr->b_l1hdr.b_pdata, !=, NULL);
+	ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
 
 	/*
 	 * If the hdr is currently being written to the l2arc then
@@ -2745,10 +2746,10 @@ arc_hdr_free_pdata(arc_buf_hdr_t *hdr)
 		arc_hdr_free_on_write(hdr);
 		ARCSTAT_BUMP(arcstat_l2_free_on_write);
 	} else {
-		arc_free_data_buf(hdr, hdr->b_l1hdr.b_pdata,
+		arc_free_data_abd(hdr, hdr->b_l1hdr.b_pabd,
 		    arc_hdr_size(hdr), hdr);
 	}
-	hdr->b_l1hdr.b_pdata = NULL;
+	hdr->b_l1hdr.b_pabd = NULL;
 	hdr->b_l1hdr.b_byteswap = DMU_BSWAP_NUMFUNCS;
 
 	ARCSTAT_INCR(arcstat_compressed_size, -arc_hdr_size(hdr));
@@ -2784,7 +2785,7 @@ arc_hdr_alloc(uint64_t spa, int32_t psize, int32_t lsize,
 	 * the compressed or uncompressed data depending on the block
 	 * it references and compressed arc enablement.
 	 */
-	arc_hdr_alloc_pdata(hdr);
+	arc_hdr_alloc_pabd(hdr);
 	ASSERT(refcount_is_zero(&hdr->b_l1hdr.b_refcnt));
 
 	return (hdr);
@@ -2824,7 +2825,7 @@ arc_hdr_realloc(arc_buf_hdr_t *hdr, kmem_cache_t *old, kmem_cache_t *new)
 		nhdr->b_l1hdr.b_state = arc_l2c_only;
 
 		/* Verify previous threads set to NULL before freeing */
-		ASSERT3P(nhdr->b_l1hdr.b_pdata, ==, NULL);
+		ASSERT3P(nhdr->b_l1hdr.b_pabd, ==, NULL);
 	} else {
 		ASSERT3P(hdr->b_l1hdr.b_buf, ==, NULL);
 		ASSERT0(hdr->b_l1hdr.b_bufcnt);
@@ -2842,11 +2843,11 @@ arc_hdr_realloc(arc_buf_hdr_t *hdr, kmem_cache_t *old, kmem_cache_t *new)
 		/*
 		 * A buffer must not be moved into the arc_l2c_only
 		 * state if it's not finished being written out to the
-		 * l2arc device. Otherwise, the b_l1hdr.b_pdata field
+		 * l2arc device. Otherwise, the b_l1hdr.b_pabd field
 		 * might try to be accessed, even though it was removed.
 		 */
 		VERIFY(!HDR_L2_WRITING(hdr));
-		VERIFY3P(hdr->b_l1hdr.b_pdata, ==, NULL);
+		VERIFY3P(hdr->b_l1hdr.b_pabd, ==, NULL);
 
 		arc_hdr_clear_flags(nhdr, ARC_FLAG_HAS_L1HDR);
 	}
@@ -2931,6 +2932,18 @@ arc_alloc_compressed_buf(spa_t *spa, void *tag, uint64_t psize, uint64_t lsize,
 	arc_buf_thaw(buf);
 	ASSERT3P(hdr->b_l1hdr.b_freeze_cksum, ==, NULL);
 
+	if (!arc_buf_is_shared(buf)) {
+		/*
+		 * To ensure that the hdr has the correct data in it if we call
+		 * arc_decompress() on this buf before it's been written to
+		 * disk, it's easiest if we just set up sharing between the
+		 * buf and the hdr.
+		 */
+		ASSERT(!abd_is_linear(hdr->b_l1hdr.b_pabd));
+		arc_hdr_free_pabd(hdr);
+		arc_share_buf(hdr, buf);
+	}
+
 	return (buf);
 }
 
@@ -2999,9 +3012,8 @@ arc_hdr_destroy(arc_buf_hdr_t *hdr)
 		while (hdr->b_l1hdr.b_buf != NULL)
 			arc_buf_destroy_impl(hdr->b_l1hdr.b_buf);
 
-		if (hdr->b_l1hdr.b_pdata != NULL) {
-			arc_hdr_free_pdata(hdr);
-		}
+		if (hdr->b_l1hdr.b_pabd != NULL)
+			arc_hdr_free_pabd(hdr);
 	}
 
 	ASSERT3P(hdr->b_hash_next, ==, NULL);
@@ -3068,7 +3080,7 @@ arc_evict_hdr(arc_buf_hdr_t *hdr, kmutex_t *hash_lock)
 
 		/*
 		 * l2arc_write_buffers() relies on a header's L1 portion
-		 * (i.e. its b_pdata field) during its write phase.
+		 * (i.e. its b_pabd field) during it's write phase.
 		 * Thus, we cannot push a header onto the arc_l2c_only
 		 * state (removing its L1 piece) until the header is
 		 * done being written to the l2arc.
@@ -3084,7 +3096,7 @@ arc_evict_hdr(arc_buf_hdr_t *hdr, kmutex_t *hash_lock)
 		DTRACE_PROBE1(arc__delete, arc_buf_hdr_t *, hdr);
 
 		if (HDR_HAS_L2HDR(hdr)) {
-			ASSERT(hdr->b_l1hdr.b_pdata == NULL);
+			ASSERT(hdr->b_l1hdr.b_pabd == NULL);
 			/*
 			 * This buffer is cached on the 2nd Level ARC;
 			 * don't destroy the header.
@@ -3149,9 +3161,9 @@ arc_evict_hdr(arc_buf_hdr_t *hdr, kmutex_t *hash_lock)
 		 * If this hdr is being evicted and has a compressed
 		 * buffer then we discard it here before we change states.
 		 * This ensures that the accounting is updated correctly
-		 * in arc_free_data_buf().
+		 * in arc_free_data_impl().
 		 */
-		arc_hdr_free_pdata(hdr);
+		arc_hdr_free_pabd(hdr);
 
 		arc_change_state(evicted_state, hdr, hash_lock);
 		ASSERT(HDR_IN_HASH_TABLE(hdr));
@@ -3249,7 +3261,7 @@ arc_evict_state_impl(multilist_t *ml, int idx, arc_buf_hdr_t *marker,
 			 * thread. If we used cv_broadcast, we could
 			 * wake up "too many" threads causing arc_size
 			 * to significantly overflow arc_c; since
-			 * arc_get_data_buf() doesn't check for overflow
+			 * arc_get_data_impl() doesn't check for overflow
 			 * when it's woken up (it doesn't because it's
 			 * possible for the ARC to be overflowing while
 			 * full of un-evictable buffers, and the
@@ -4154,13 +4166,13 @@ arc_kmem_reap_now(void)
 }
 
 /*
- * Threads can block in arc_get_data_buf() waiting for this thread to evict
+ * Threads can block in arc_get_data_impl() waiting for this thread to evict
  * enough data and signal them to proceed. When this happens, the threads in
- * arc_get_data_buf() are sleeping while holding the hash lock for their
+ * arc_get_data_impl() are sleeping while holding the hash lock for their
  * particular arc header. Thus, we must be careful to never sleep on a
  * hash lock in this thread. This is to prevent the following deadlock:
  *
- *  - Thread A sleeps on CV in arc_get_data_buf() holding hash lock "L",
+ *  - Thread A sleeps on CV in arc_get_data_impl() holding hash lock "L",
  *    waiting for the reclaim thread to signal it.
  *
  *  - arc_reclaim_thread() tries to acquire hash lock "L" using mutex_enter,
@@ -4509,18 +4521,45 @@ arc_is_overflowing(void)
 	return (arc_size >= arc_c + overflow);
 }
 
+static abd_t *
+arc_get_data_abd(arc_buf_hdr_t *hdr, uint64_t size, void *tag)
+{
+	arc_buf_contents_t type = arc_buf_type(hdr);
+
+	arc_get_data_impl(hdr, size, tag);
+	if (type == ARC_BUFC_METADATA) {
+		return (abd_alloc(size, B_TRUE));
+	} else {
+		ASSERT(type == ARC_BUFC_DATA);
+		return (abd_alloc(size, B_FALSE));
+	}
+}
+
+static void *
+arc_get_data_buf(arc_buf_hdr_t *hdr, uint64_t size, void *tag)
+{
+	arc_buf_contents_t type = arc_buf_type(hdr);
+
+	arc_get_data_impl(hdr, size, tag);
+	if (type == ARC_BUFC_METADATA) {
+		return (zio_buf_alloc(size));
+	} else {
+		ASSERT(type == ARC_BUFC_DATA);
+		return (zio_data_buf_alloc(size));
+	}
+}
+
 /*
  * Allocate a block and return it to the caller. If we are hitting the
  * hard limit for the cache size, we must sleep, waiting for the eviction
  * thread to catch up. If we're past the target size but below the hard
  * limit, we'll only signal the reclaim thread and continue on.
  */
-static void *
-arc_get_data_buf(arc_buf_hdr_t *hdr, uint64_t size, void *tag)
+static void
+arc_get_data_impl(arc_buf_hdr_t *hdr, uint64_t size, void *tag)
 {
-	void *datap = NULL;
-	arc_state_t		*state = hdr->b_l1hdr.b_state;
-	arc_buf_contents_t	type = arc_buf_type(hdr);
+	arc_state_t *state = hdr->b_l1hdr.b_state;
+	arc_buf_contents_t type = arc_buf_type(hdr);
 
 	arc_adapt(size, state);
 
@@ -4562,11 +4601,8 @@ arc_get_data_buf(arc_buf_hdr_t *hdr, uint64_t size, void *tag)
 
 	VERIFY3U(hdr->b_type, ==, type);
 	if (type == ARC_BUFC_METADATA) {
-		datap = zio_buf_alloc(size);
 		arc_space_consume(size, ARC_SPACE_META);
 	} else {
-		ASSERT(type == ARC_BUFC_DATA);
-		datap = zio_data_buf_alloc(size);
 		arc_space_consume(size, ARC_SPACE_DATA);
 	}
 
@@ -4602,14 +4638,34 @@ arc_get_data_buf(arc_buf_hdr_t *hdr, uint64_t size, void *tag)
 		    refcount_count(&arc_mru->arcs_size) > arc_p))
 			arc_p = MIN(arc_c, arc_p + size);
 	}
-	return (datap);
+}
+
+static void
+arc_free_data_abd(arc_buf_hdr_t *hdr, abd_t *abd, uint64_t size, void *tag)
+{
+	arc_free_data_impl(hdr, size, tag);
+	abd_free(abd);
+}
+
+static void
+arc_free_data_buf(arc_buf_hdr_t *hdr, void *buf, uint64_t size, void *tag)
+{
+	arc_buf_contents_t type = arc_buf_type(hdr);
+
+	arc_free_data_impl(hdr, size, tag);
+	if (type == ARC_BUFC_METADATA) {
+		zio_buf_free(buf, size);
+	} else {
+		ASSERT(type == ARC_BUFC_DATA);
+		zio_data_buf_free(buf, size);
+	}
 }
 
 /*
  * Free the arc data buffer.
  */
 static void
-arc_free_data_buf(arc_buf_hdr_t *hdr, void *data, uint64_t size, void *tag)
+arc_free_data_impl(arc_buf_hdr_t *hdr, uint64_t size, void *tag)
 {
 	arc_state_t *state = hdr->b_l1hdr.b_state;
 	arc_buf_contents_t type = arc_buf_type(hdr);
@@ -4626,11 +4682,9 @@ arc_free_data_buf(arc_buf_hdr_t *hdr, void *data, uint64_t size, void *tag)
 
 	VERIFY3U(hdr->b_type, ==, type);
 	if (type == ARC_BUFC_METADATA) {
-		zio_buf_free(data, size);
 		arc_space_return(size, ARC_SPACE_META);
 	} else {
 		ASSERT(type == ARC_BUFC_DATA);
-		zio_data_buf_free(data, size);
 		arc_space_return(size, ARC_SPACE_DATA);
 	}
 }
@@ -4912,7 +4966,7 @@ arc_read_done(zio_t *zio)
 	if (callback_cnt == 0) {
 		ASSERT(HDR_PREFETCH(hdr));
 		ASSERT0(hdr->b_l1hdr.b_bufcnt);
-		ASSERT3P(hdr->b_l1hdr.b_pdata, !=, NULL);
+		ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
 	}
 
 	ASSERT(refcount_is_zero(&hdr->b_l1hdr.b_refcnt) ||
@@ -5009,7 +5063,7 @@ top:
 		hdr = buf_hash_find(guid, bp, &hash_lock);
 	}
 
-	if (hdr != NULL && HDR_HAS_L1HDR(hdr) && hdr->b_l1hdr.b_pdata != NULL) {
+	if (hdr != NULL && HDR_HAS_L1HDR(hdr) && hdr->b_l1hdr.b_pabd != NULL) {
 		arc_buf_t *buf = NULL;
 		*arc_flags |= ARC_FLAG_CACHED;
 
@@ -5161,7 +5215,7 @@ top:
 				    hdr_full_cache);
 			}
 
-			ASSERT3P(hdr->b_l1hdr.b_pdata, ==, NULL);
+			ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
 			ASSERT(GHOST_STATE(hdr->b_l1hdr.b_state));
 			ASSERT(!HDR_IO_IN_PROGRESS(hdr));
 			ASSERT(refcount_is_zero(&hdr->b_l1hdr.b_refcnt));
@@ -5179,9 +5233,9 @@ top:
 			 * avoid hitting an assert in remove_reference().
 			 */
 			arc_access(hdr, hash_lock);
-			arc_hdr_alloc_pdata(hdr);
+			arc_hdr_alloc_pabd(hdr);
 		}
-		ASSERT3P(hdr->b_l1hdr.b_pdata, !=, NULL);
+		ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
 		size = arc_hdr_size(hdr);
 
 		/*
@@ -5285,7 +5339,7 @@ top:
 				ASSERT3U(HDR_GET_COMPRESS(hdr), !=,
 				    ZIO_COMPRESS_EMPTY);
 				rzio = zio_read_phys(pio, vd, addr,
-				    size, hdr->b_l1hdr.b_pdata,
+				    size, hdr->b_l1hdr.b_pabd,
 				    ZIO_CHECKSUM_OFF,
 				    l2arc_read_done, cb, priority,
 				    zio_flags | ZIO_FLAG_DONT_CACHE |
@@ -5325,7 +5379,7 @@ top:
 			}
 		}
 
-		rzio = zio_read(pio, spa, bp, hdr->b_l1hdr.b_pdata, size,
+		rzio = zio_read(pio, spa, bp, hdr->b_l1hdr.b_pabd, size,
 		    arc_read_done, hdr, priority, zio_flags, zb);
 
 		if (*arc_flags & ARC_FLAG_WAIT) {
@@ -5557,16 +5611,17 @@ arc_release(arc_buf_t *buf, void *tag)
 			arc_unshare_buf(hdr, buf);
 
 			/*
-			 * Now we need to recreate the hdr's b_pdata. Since we
+			 * Now we need to recreate the hdr's b_pabd. Since we
 			 * have lastbuf handy, we try to share with it, but if
-			 * we can't then we allocate a new b_pdata and copy the
+			 * we can't then we allocate a new b_pabd and copy the
 			 * data from buf into it.
 			 */
 			if (arc_can_share(hdr, lastbuf)) {
 				arc_share_buf(hdr, lastbuf);
 			} else {
-				arc_hdr_alloc_pdata(hdr);
-				bcopy(buf->b_data, hdr->b_l1hdr.b_pdata, psize);
+				arc_hdr_alloc_pabd(hdr);
+				abd_copy_from_buf(hdr->b_l1hdr.b_pabd,
+				    buf->b_data, psize);
 			}
 			VERIFY3P(lastbuf->b_data, !=, NULL);
 		} else if (HDR_SHARED_DATA(hdr)) {
@@ -5582,7 +5637,7 @@ arc_release(arc_buf_t *buf, void *tag)
 			    HDR_GET_COMPRESS(hdr) != ZIO_COMPRESS_OFF);
 			ASSERT(!ARC_BUF_SHARED(buf));
 		}
-		ASSERT3P(hdr->b_l1hdr.b_pdata, !=, NULL);
+		ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
 		ASSERT3P(state, !=, arc_l2c_only);
 
 		(void) refcount_remove_many(&state->arcs_size,
@@ -5601,7 +5656,7 @@ arc_release(arc_buf_t *buf, void *tag)
 		mutex_exit(hash_lock);
 
 		/*
-		 * Allocate a new hdr. The new hdr will contain a b_pdata
+		 * Allocate a new hdr. The new hdr will contain a b_pabd
 		 * buffer which will be freed in arc_write().
 		 */
 		nhdr = arc_hdr_alloc(spa, psize, lsize, compress, type);
@@ -5677,6 +5732,7 @@ arc_write_ready(zio_t *zio)
 	arc_buf_hdr_t *hdr = buf->b_hdr;
 	uint64_t psize = BP_IS_HOLE(zio->io_bp) ? 0 : BP_GET_PSIZE(zio->io_bp);
 	enum zio_compress compress;
+	fstrans_cookie_t cookie = spl_fstrans_mark();
 
 	ASSERT(HDR_HAS_L1HDR(hdr));
 	ASSERT(!refcount_is_zero(&buf->b_hdr->b_l1hdr.b_refcnt));
@@ -5690,15 +5746,15 @@ arc_write_ready(zio_t *zio)
 	if (zio->io_flags & ZIO_FLAG_REEXECUTED) {
 		arc_cksum_free(hdr);
 		arc_buf_unwatch(buf);
-		if (hdr->b_l1hdr.b_pdata != NULL) {
+		if (hdr->b_l1hdr.b_pabd != NULL) {
 			if (arc_buf_is_shared(buf)) {
 				arc_unshare_buf(hdr, buf);
 			} else {
-				arc_hdr_free_pdata(hdr);
+				arc_hdr_free_pabd(hdr);
 			}
 		}
 	}
-	ASSERT3P(hdr->b_l1hdr.b_pdata, ==, NULL);
+	ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
 	ASSERT(!HDR_SHARED_DATA(hdr));
 	ASSERT(!arc_buf_is_shared(buf));
 
@@ -5720,33 +5776,47 @@ arc_write_ready(zio_t *zio)
 	arc_hdr_set_compress(hdr, compress);
 
 	/*
-	 * If the hdr is compressed, then copy the compressed
-	 * zio contents into arc_buf_hdr_t. Otherwise, copy the original
-	 * data buf into the hdr. Ideally, we would like to always copy the
-	 * io_data into b_pdata but the user may have disabled compressed
-	 * arc thus the on-disk block may or may not match what we maintain
-	 * in the hdr's b_pdata field.
+	 * Fill the hdr with data. If the hdr is compressed, the data we want
+	 * is available from the zio, otherwise we can take it from the buf.
+	 *
+	 * We might be able to share the buf's data with the hdr here. However,
+	 * doing so would cause the ARC to be full of linear ABDs if we write a
+	 * lot of shareable data. As a compromise, we check whether scattered
+	 * ABDs are allowed, and assume that if they are then the user wants
+	 * the ARC to be primarily filled with them regardless of the data being
+	 * written. Therefore, if they're allowed then we allocate one and copy
+	 * the data into it; otherwise, we share the data directly if we can.
 	 */
-	if (HDR_GET_COMPRESS(hdr) != ZIO_COMPRESS_OFF &&
-	    !ARC_BUF_COMPRESSED(buf)) {
-		ASSERT3U(BP_GET_COMPRESS(zio->io_bp), !=, ZIO_COMPRESS_OFF);
-		ASSERT3U(psize, >, 0);
-		arc_hdr_alloc_pdata(hdr);
-		bcopy(zio->io_data, hdr->b_l1hdr.b_pdata, psize);
+	if (zfs_abd_scatter_enabled || !arc_can_share(hdr, buf)) {
+		arc_hdr_alloc_pabd(hdr);
+
+		/*
+		 * Ideally, we would always copy the io_abd into b_pabd, but the
+		 * user may have disabled compressed ARC, thus we must check the
+		 * hdr's compression setting rather than the io_bp's.
+		 */
+		if (HDR_GET_COMPRESS(hdr) != ZIO_COMPRESS_OFF) {
+			ASSERT3U(BP_GET_COMPRESS(zio->io_bp), !=,
+			    ZIO_COMPRESS_OFF);
+			ASSERT3U(psize, >, 0);
+
+			abd_copy(hdr->b_l1hdr.b_pabd, zio->io_abd, psize);
+		} else {
+			ASSERT3U(zio->io_orig_size, ==, arc_hdr_size(hdr));
+
+			abd_copy_from_buf(hdr->b_l1hdr.b_pabd, buf->b_data,
+			    arc_buf_size(buf));
+		}
 	} else {
-		ASSERT3P(buf->b_data, ==, zio->io_orig_data);
+		ASSERT3P(buf->b_data, ==, abd_to_buf(zio->io_orig_abd));
 		ASSERT3U(zio->io_orig_size, ==, arc_buf_size(buf));
 		ASSERT3U(hdr->b_l1hdr.b_bufcnt, ==, 1);
 
-		/*
-		 * This hdr is not compressed so we're able to share
-		 * the arc_buf_t data buffer with the hdr.
-		 */
 		arc_share_buf(hdr, buf);
-		ASSERT0(bcmp(zio->io_orig_data, hdr->b_l1hdr.b_pdata,
-		    HDR_GET_LSIZE(hdr)));
 	}
+
 	arc_hdr_verify(hdr, zio->io_bp);
+	spl_fstrans_unmark(cookie);
 }
 
 static void
@@ -5850,6 +5920,7 @@ arc_write_done(zio_t *zio)
 	ASSERT(!refcount_is_zero(&hdr->b_l1hdr.b_refcnt));
 	callback->awcb_done(zio, buf, callback->awcb_private);
 
+	abd_put(zio->io_abd);
 	kmem_free(callback, sizeof (arc_write_callback_t));
 }
 
@@ -5886,10 +5957,10 @@ arc_write(zio_t *pio, spa_t *spa, uint64_t txg,
 	callback->awcb_buf = buf;
 
 	/*
-	 * The hdr's b_pdata is now stale, free it now. A new data block
+	 * The hdr's b_pabd is now stale, free it now. A new data block
 	 * will be allocated when the zio pipeline calls arc_write_ready().
 	 */
-	if (hdr->b_l1hdr.b_pdata != NULL) {
+	if (hdr->b_l1hdr.b_pabd != NULL) {
 		/*
 		 * If the buf is currently sharing the data block with
 		 * the hdr then we need to break that relationship here.
@@ -5899,15 +5970,16 @@ arc_write(zio_t *pio, spa_t *spa, uint64_t txg,
 		if (arc_buf_is_shared(buf)) {
 			arc_unshare_buf(hdr, buf);
 		} else {
-			arc_hdr_free_pdata(hdr);
+			arc_hdr_free_pabd(hdr);
 		}
 		VERIFY3P(buf->b_data, !=, NULL);
 		arc_hdr_set_compress(hdr, ZIO_COMPRESS_OFF);
 	}
 	ASSERT(!arc_buf_is_shared(buf));
-	ASSERT3P(hdr->b_l1hdr.b_pdata, ==, NULL);
+	ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
 
-	zio = zio_write(pio, spa, txg, bp, buf->b_data,
+	zio = zio_write(pio, spa, txg, bp,
+	    abd_get_from_buf(buf->b_data, HDR_GET_LSIZE(hdr)),
 	    HDR_GET_LSIZE(hdr), arc_buf_size(buf), zp,
 	    arc_write_ready,
 	    (children_ready != NULL) ? arc_write_children_ready : NULL,
@@ -6768,13 +6840,8 @@ l2arc_do_free_on_write(void)
 
 	for (df = list_tail(buflist); df; df = df_prev) {
 		df_prev = list_prev(buflist, df);
-		ASSERT3P(df->l2df_data, !=, NULL);
-		if (df->l2df_type == ARC_BUFC_METADATA) {
-			zio_buf_free(df->l2df_data, df->l2df_size);
-		} else {
-			ASSERT(df->l2df_type == ARC_BUFC_DATA);
-			zio_data_buf_free(df->l2df_data, df->l2df_size);
-		}
+		ASSERT3P(df->l2df_abd, !=, NULL);
+		abd_free(df->l2df_abd);
 		list_remove(buflist, df);
 		kmem_free(df, sizeof (l2arc_data_free_t));
 	}
@@ -6928,12 +6995,12 @@ l2arc_read_done(zio_t *zio)
 	mutex_enter(hash_lock);
 	ASSERT3P(hash_lock, ==, HDR_LOCK(hdr));
 
-	ASSERT3P(zio->io_data, !=, NULL);
+	ASSERT3P(zio->io_abd, !=, NULL);
 
 	/*
 	 * Check this survived the L2ARC journey.
 	 */
-	ASSERT3P(zio->io_data, ==, hdr->b_l1hdr.b_pdata);
+	ASSERT3P(zio->io_abd, ==, hdr->b_l1hdr.b_pabd);
 	zio->io_bp_copy = cb->l2rcb_bp;	/* XXX fix in L2ARC 2.0	*/
 	zio->io_bp = &zio->io_bp_copy;	/* XXX fix in L2ARC 2.0	*/
 
@@ -6967,7 +7034,7 @@ l2arc_read_done(zio_t *zio)
 			ASSERT(!pio || pio->io_child_type == ZIO_CHILD_LOGICAL);
 
 			zio_nowait(zio_read(pio, zio->io_spa, zio->io_bp,
-			    hdr->b_l1hdr.b_pdata, zio->io_size, arc_read_done,
+			    hdr->b_l1hdr.b_pabd, zio->io_size, arc_read_done,
 			    hdr, zio->io_priority, cb->l2rcb_flags,
 			    &cb->l2rcb_zb));
 		}
@@ -7191,7 +7258,7 @@ l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz)
 		for (; hdr; hdr = hdr_prev) {
 			kmutex_t *hash_lock;
 			uint64_t asize, size;
-			void *to_write;
+			abd_t *to_write;
 
 			if (arc_warm == B_FALSE)
 				hdr_prev = multilist_sublist_next(mls, hdr);
@@ -7264,7 +7331,7 @@ l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz)
 			ASSERT(HDR_HAS_L1HDR(hdr));
 
 			ASSERT3U(HDR_GET_PSIZE(hdr), >, 0);
-			ASSERT3P(hdr->b_l1hdr.b_pdata, !=, NULL);
+			ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
 			ASSERT3U(arc_hdr_size(hdr), >, 0);
 			size = arc_hdr_size(hdr);
 
@@ -7280,18 +7347,13 @@ l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz)
 			 * add it to the l2arc_free_on_write queue.
 			 */
 			if (!HDR_SHARED_DATA(hdr)) {
-				to_write = hdr->b_l1hdr.b_pdata;
+				to_write = hdr->b_l1hdr.b_pabd;
 			} else {
-				arc_buf_contents_t type = arc_buf_type(hdr);
-				if (type == ARC_BUFC_METADATA) {
-					to_write = zio_buf_alloc(size);
-				} else {
-					ASSERT3U(type, ==, ARC_BUFC_DATA);
-					to_write = zio_data_buf_alloc(size);
-				}
-
-				bcopy(hdr->b_l1hdr.b_pdata, to_write, size);
-				l2arc_free_data_on_write(to_write, size, type);
+				to_write = abd_alloc_for_io(size,
+				    HDR_ISTYPE_METADATA(hdr));
+				abd_copy(to_write, hdr->b_l1hdr.b_pabd, size);
+				l2arc_free_abd_on_write(to_write, size,
+				    arc_buf_type(hdr));
 			}
 			wzio = zio_write_phys(pio, dev->l2ad_vdev,
 			    hdr->b_l2hdr.b_daddr, size, to_write,
diff --git a/module/zfs/blkptr.c b/module/zfs/blkptr.c
index d56e19996..99accfa0f 100644
--- a/module/zfs/blkptr.c
+++ b/module/zfs/blkptr.c
@@ -14,7 +14,7 @@
  */
 
 /*
- * Copyright (c) 2013 by Delphix. All rights reserved.
+ * Copyright (c) 2013, 2016 by Delphix. All rights reserved.
  */
 
 #include <sys/zfs_context.h>
diff --git a/module/zfs/dbuf.c b/module/zfs/dbuf.c
index 1d8c0518a..6e7a5a0fb 100644
--- a/module/zfs/dbuf.c
+++ b/module/zfs/dbuf.c
@@ -46,6 +46,7 @@
 #include <sys/range_tree.h>
 #include <sys/trace_dbuf.h>
 #include <sys/callb.h>
+#include <sys/abd.h>
 
 struct dbuf_hold_impl_data {
 	/* Function arguments */
@@ -3709,6 +3710,9 @@ dbuf_write_override_done(zio_t *zio)
 	mutex_exit(&db->db_mtx);
 
 	dbuf_write_done(zio, NULL, db);
+
+	if (zio->io_abd != NULL)
+		abd_put(zio->io_abd);
 }
 
 /* Issue I/O to commit a dirty buffer to disk. */
@@ -3801,7 +3805,8 @@ dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx)
 		 * The BP for this block has been provided by open context
 		 * (by dmu_sync() or dmu_buf_write_embedded()).
 		 */
-		void *contents = (data != NULL) ? data->b_data : NULL;
+		abd_t *contents = (data != NULL) ?
+		    abd_get_from_buf(data->b_data, arc_buf_size(data)) : NULL;
 
 		dr->dr_zio = zio_write(zio, os->os_spa, txg,
 		    &dr->dr_bp_copy, contents, db->db.db_size, db->db.db_size,
diff --git a/module/zfs/ddt.c b/module/zfs/ddt.c
index 09a3536f5..cbec70057 100644
--- a/module/zfs/ddt.c
+++ b/module/zfs/ddt.c
@@ -21,7 +21,7 @@
 
 /*
  * Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
+ * Copyright (c) 2012, 2016 by Delphix. All rights reserved.
  */
 
 #include <sys/zfs_context.h>
@@ -36,6 +36,7 @@
 #include <sys/zio_checksum.h>
 #include <sys/zio_compress.h>
 #include <sys/dsl_scan.h>
+#include <sys/abd.h>
 
 static kmem_cache_t *ddt_cache;
 static kmem_cache_t *ddt_entry_cache;
@@ -706,9 +707,8 @@ ddt_free(ddt_entry_t *dde)
 	for (p = 0; p < DDT_PHYS_TYPES; p++)
 		ASSERT(dde->dde_lead_zio[p] == NULL);
 
-	if (dde->dde_repair_data != NULL)
-		zio_buf_free(dde->dde_repair_data,
-		    DDK_GET_PSIZE(&dde->dde_key));
+	if (dde->dde_repair_abd != NULL)
+		abd_free(dde->dde_repair_abd);
 
 	cv_destroy(&dde->dde_cv);
 	kmem_cache_free(ddt_entry_cache, dde);
@@ -1002,7 +1002,7 @@ ddt_repair_done(ddt_t *ddt, ddt_entry_t *dde)
 
 	ddt_enter(ddt);
 
-	if (dde->dde_repair_data != NULL && spa_writeable(ddt->ddt_spa) &&
+	if (dde->dde_repair_abd != NULL && spa_writeable(ddt->ddt_spa) &&
 	    avl_find(&ddt->ddt_repair_tree, dde, &where) == NULL)
 		avl_insert(&ddt->ddt_repair_tree, dde, where);
 	else
@@ -1040,7 +1040,7 @@ ddt_repair_entry(ddt_t *ddt, ddt_entry_t *dde, ddt_entry_t *rdde, zio_t *rio)
 			continue;
 		ddt_bp_create(ddt->ddt_checksum, ddk, ddp, &blk);
 		zio_nowait(zio_rewrite(zio, zio->io_spa, 0, &blk,
-		    rdde->dde_repair_data, DDK_GET_PSIZE(rddk), NULL, NULL,
+		    rdde->dde_repair_abd, DDK_GET_PSIZE(rddk), NULL, NULL,
 		    ZIO_PRIORITY_SYNC_WRITE, ZIO_DDT_CHILD_FLAGS(zio), NULL));
 	}
 
diff --git a/module/zfs/dmu.c b/module/zfs/dmu.c
index a817fdbce..b5ddec2d9 100644
--- a/module/zfs/dmu.c
+++ b/module/zfs/dmu.c
@@ -47,6 +47,7 @@
 #include <sys/zio_compress.h>
 #include <sys/sa.h>
 #include <sys/zfeature.h>
+#include <sys/abd.h>
 #ifdef _KERNEL
 #include <sys/vmsystm.h>
 #include <sys/zfs_znode.h>
@@ -1513,6 +1514,7 @@ dmu_sync_late_arrival_done(zio_t *zio)
 
 	dsa->dsa_done(dsa->dsa_zgd, zio->io_error);
 
+	abd_put(zio->io_abd);
 	kmem_free(dsa, sizeof (*dsa));
 }
 
@@ -1537,11 +1539,11 @@ dmu_sync_late_arrival(zio_t *pio, objset_t *os, dmu_sync_cb_t *done, zgd_t *zgd,
 	dsa->dsa_zgd = zgd;
 	dsa->dsa_tx = tx;
 
-	zio_nowait(zio_write(pio, os->os_spa, dmu_tx_get_txg(tx),
-	    zgd->zgd_bp, zgd->zgd_db->db_data, zgd->zgd_db->db_size,
-	    zgd->zgd_db->db_size, zp, dmu_sync_late_arrival_ready, NULL,
-	    NULL, dmu_sync_late_arrival_done, dsa, ZIO_PRIORITY_SYNC_WRITE,
-	    ZIO_FLAG_CANFAIL, zb));
+	zio_nowait(zio_write(pio, os->os_spa, dmu_tx_get_txg(tx), zgd->zgd_bp,
+	    abd_get_from_buf(zgd->zgd_db->db_data, zgd->zgd_db->db_size),
+	    zgd->zgd_db->db_size, zgd->zgd_db->db_size, zp,
+	    dmu_sync_late_arrival_ready, NULL, NULL, dmu_sync_late_arrival_done,
+	    dsa, ZIO_PRIORITY_SYNC_WRITE, ZIO_FLAG_CANFAIL, zb));
 
 	return (0);
 }
@@ -2062,6 +2064,7 @@ byteswap_uint8_array(void *vbuf, size_t size)
 void
 dmu_init(void)
 {
+	abd_init();
 	zfs_dbgmsg_init();
 	sa_cache_init();
 	xuio_stat_init();
@@ -2087,6 +2090,7 @@ dmu_fini(void)
 	xuio_stat_fini();
 	sa_cache_fini();
 	zfs_dbgmsg_fini();
+	abd_fini();
 }
 
 #if defined(_KERNEL) && defined(HAVE_SPL)
diff --git a/module/zfs/dmu_send.c b/module/zfs/dmu_send.c
index f9414ea3a..af6208e4d 100644
--- a/module/zfs/dmu_send.c
+++ b/module/zfs/dmu_send.c
@@ -166,7 +166,7 @@ dump_record(dmu_sendarg_t *dsp, void *payload, int payload_len)
 {
 	ASSERT3U(offsetof(dmu_replay_record_t, drr_u.drr_checksum.drr_checksum),
 	    ==, sizeof (dmu_replay_record_t) - sizeof (zio_cksum_t));
-	fletcher_4_incremental_native(dsp->dsa_drr,
+	(void) fletcher_4_incremental_native(dsp->dsa_drr,
 	    offsetof(dmu_replay_record_t, drr_u.drr_checksum.drr_checksum),
 	    &dsp->dsa_zc);
 	if (dsp->dsa_drr->drr_type == DRR_BEGIN) {
@@ -179,13 +179,13 @@ dump_record(dmu_sendarg_t *dsp, void *payload, int payload_len)
 	if (dsp->dsa_drr->drr_type == DRR_END) {
 		dsp->dsa_sent_end = B_TRUE;
 	}
-	fletcher_4_incremental_native(&dsp->dsa_drr->
+	(void) fletcher_4_incremental_native(&dsp->dsa_drr->
 	    drr_u.drr_checksum.drr_checksum,
 	    sizeof (zio_cksum_t), &dsp->dsa_zc);
 	if (dump_bytes(dsp, dsp->dsa_drr, sizeof (dmu_replay_record_t)) != 0)
 		return (SET_ERROR(EINTR));
 	if (payload_len != 0) {
-		fletcher_4_incremental_native(payload, payload_len,
+		(void) fletcher_4_incremental_native(payload, payload_len,
 		    &dsp->dsa_zc);
 		if (dump_bytes(dsp, payload, payload_len) != 0)
 			return (SET_ERROR(EINTR));
@@ -1786,11 +1786,11 @@ dmu_recv_begin(char *tofs, char *tosnap, dmu_replay_record_t *drr_begin,
 
 	if (drc->drc_drrb->drr_magic == BSWAP_64(DMU_BACKUP_MAGIC)) {
 		drc->drc_byteswap = B_TRUE;
-		fletcher_4_incremental_byteswap(drr_begin,
+		(void) fletcher_4_incremental_byteswap(drr_begin,
 		    sizeof (dmu_replay_record_t), &drc->drc_cksum);
 		byteswap_record(drr_begin);
 	} else if (drc->drc_drrb->drr_magic == DMU_BACKUP_MAGIC) {
-		fletcher_4_incremental_native(drr_begin,
+		(void) fletcher_4_incremental_native(drr_begin,
 		    sizeof (dmu_replay_record_t), &drc->drc_cksum);
 	} else {
 		return (SET_ERROR(EINVAL));
@@ -2470,9 +2470,9 @@ static void
 receive_cksum(struct receive_arg *ra, int len, void *buf)
 {
 	if (ra->byteswap) {
-		fletcher_4_incremental_byteswap(buf, len, &ra->cksum);
+		(void) fletcher_4_incremental_byteswap(buf, len, &ra->cksum);
 	} else {
-		fletcher_4_incremental_native(buf, len, &ra->cksum);
+		(void) fletcher_4_incremental_native(buf, len, &ra->cksum);
 	}
 }
 
diff --git a/module/zfs/dsl_scan.c b/module/zfs/dsl_scan.c
index 41b3ce79b..fd7a53bc9 100644
--- a/module/zfs/dsl_scan.c
+++ b/module/zfs/dsl_scan.c
@@ -20,7 +20,7 @@
  */
 /*
  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2011, 2015 by Delphix. All rights reserved.
+ * Copyright (c) 2011, 2016 by Delphix. All rights reserved.
  * Copyright 2016 Gary Mills
  */
 
@@ -47,6 +47,7 @@
 #include <sys/sa.h>
 #include <sys/sa_impl.h>
 #include <sys/zfeature.h>
+#include <sys/abd.h>
 #ifdef _KERNEL
 #include <sys/zfs_vfsops.h>
 #endif
@@ -1820,7 +1821,7 @@ dsl_scan_scrub_done(zio_t *zio)
 {
 	spa_t *spa = zio->io_spa;
 
-	zio_data_buf_free(zio->io_data, zio->io_size);
+	abd_free(zio->io_abd);
 
 	mutex_enter(&spa->spa_scrub_lock);
 	spa->spa_scrub_inflight--;
@@ -1904,7 +1905,6 @@ dsl_scan_scrub_cb(dsl_pool_t *dp,
 	if (needs_io && !zfs_no_scrub_io) {
 		vdev_t *rvd = spa->spa_root_vdev;
 		uint64_t maxinflight = rvd->vdev_children * zfs_top_maxinflight;
-		void *data = zio_data_buf_alloc(size);
 
 		mutex_enter(&spa->spa_scrub_lock);
 		while (spa->spa_scrub_inflight >= maxinflight)
@@ -1919,9 +1919,9 @@ dsl_scan_scrub_cb(dsl_pool_t *dp,
 		if (ddi_get_lbolt64() - spa->spa_last_io <= zfs_scan_idle)
 			delay(scan_delay);
 
-		zio_nowait(zio_read(NULL, spa, bp, data, size,
-		    dsl_scan_scrub_done, NULL, ZIO_PRIORITY_SCRUB,
-		    zio_flags, zb));
+		zio_nowait(zio_read(NULL, spa, bp,
+		    abd_alloc_for_io(size, B_FALSE), size, dsl_scan_scrub_done,
+		    NULL, ZIO_PRIORITY_SCRUB, zio_flags, zb));
 	}
 
 	/* do not relocate this block */
diff --git a/module/zfs/edonr_zfs.c b/module/zfs/edonr_zfs.c
index 3c7d98656..e92da6d6c 100644
--- a/module/zfs/edonr_zfs.c
+++ b/module/zfs/edonr_zfs.c
@@ -22,20 +22,32 @@
  * Copyright 2013 Saso Kiselkov.  All rights reserved.
  * Use is subject to license terms.
  */
+/*
+ * Copyright (c) 2016 by Delphix. All rights reserved.
+ */
 #include <sys/zfs_context.h>
 #include <sys/zio.h>
 #include <sys/edonr.h>
 #include <sys/zfs_context.h>	/* For CTASSERT() */
+#include <sys/abd.h>
 
 #define	EDONR_MODE		512
 #define	EDONR_BLOCK_SIZE	EdonR512_BLOCK_SIZE
 
+static int
+edonr_incremental(void *buf, size_t size, void *arg)
+{
+	EdonRState *ctx = arg;
+	EdonRUpdate(ctx, buf, size * 8);
+	return (0);
+}
+
 /*
  * Native zio_checksum interface for the Edon-R hash function.
  */
 /*ARGSUSED*/
 void
-zio_checksum_edonr_native(const void *buf, uint64_t size,
+abd_checksum_edonr_native(abd_t *abd, uint64_t size,
     const void *ctx_template, zio_cksum_t *zcp)
 {
 	uint8_t		digest[EDONR_MODE / 8];
@@ -43,7 +55,7 @@ zio_checksum_edonr_native(const void *buf, uint64_t size,
 
 	ASSERT(ctx_template != NULL);
 	bcopy(ctx_template, &ctx, sizeof (ctx));
-	EdonRUpdate(&ctx, buf, size * 8);
+	(void) abd_iterate_func(abd, 0, size, edonr_incremental, &ctx);
 	EdonRFinal(&ctx, digest);
 	bcopy(digest, zcp->zc_word, sizeof (zcp->zc_word));
 }
@@ -52,12 +64,12 @@ zio_checksum_edonr_native(const void *buf, uint64_t size,
  * Byteswapped zio_checksum interface for the Edon-R hash function.
  */
 void
-zio_checksum_edonr_byteswap(const void *buf, uint64_t size,
+abd_checksum_edonr_byteswap(abd_t *abd, uint64_t size,
     const void *ctx_template, zio_cksum_t *zcp)
 {
 	zio_cksum_t	tmp;
 
-	zio_checksum_edonr_native(buf, size, ctx_template, &tmp);
+	abd_checksum_edonr_native(abd, size, ctx_template, &tmp);
 	zcp->zc_word[0] = BSWAP_64(zcp->zc_word[0]);
 	zcp->zc_word[1] = BSWAP_64(zcp->zc_word[1]);
 	zcp->zc_word[2] = BSWAP_64(zcp->zc_word[2]);
@@ -65,7 +77,7 @@ zio_checksum_edonr_byteswap(const void *buf, uint64_t size,
 }
 
 void *
-zio_checksum_edonr_tmpl_init(const zio_cksum_salt_t *salt)
+abd_checksum_edonr_tmpl_init(const zio_cksum_salt_t *salt)
 {
 	EdonRState	*ctx;
 	uint8_t		salt_block[EDONR_BLOCK_SIZE];
@@ -94,7 +106,7 @@ zio_checksum_edonr_tmpl_init(const zio_cksum_salt_t *salt)
 }
 
 void
-zio_checksum_edonr_tmpl_free(void *ctx_template)
+abd_checksum_edonr_tmpl_free(void *ctx_template)
 {
 	EdonRState	*ctx = ctx_template;
 
diff --git a/module/zfs/sha256.c b/module/zfs/sha256.c
index c8a4882f8..23a97aa3d 100644
--- a/module/zfs/sha256.c
+++ b/module/zfs/sha256.c
@@ -24,30 +24,39 @@
  */
 /*
  * Copyright 2013 Saso Kiselkov. All rights reserved.
+ * Copyright (c) 2016 by Delphix. All rights reserved.
  */
 #include <sys/zfs_context.h>
 #include <sys/zio.h>
-#include <sys/zio_checksum.h>
 #include <sys/sha2.h>
+#include <sys/abd.h>
+
+static int
+sha_incremental(void *buf, size_t size, void *arg)
+{
+	SHA2_CTX *ctx = arg;
+	SHA2Update(ctx, buf, size);
+	return (0);
+}
 
 /*ARGSUSED*/
 void
-zio_checksum_SHA256(const void *buf, uint64_t size,
+abd_checksum_SHA256(abd_t *abd, uint64_t size,
     const void *ctx_template, zio_cksum_t *zcp)
 {
 	SHA2_CTX ctx;
 	zio_cksum_t tmp;
 
 	SHA2Init(SHA256, &ctx);
-	SHA2Update(&ctx, buf, size);
+	(void) abd_iterate_func(abd, 0, size, sha_incremental, &ctx);
 	SHA2Final(&tmp, &ctx);
 
 	/*
 	 * A prior implementation of this function had a
 	 * private SHA256 implementation always wrote things out in
 	 * Big Endian and there wasn't a byteswap variant of it.
-	 * To preseve on disk compatibility we need to force that
-	 * behaviour.
+	 * To preserve on disk compatibility we need to force that
+	 * behavior.
 	 */
 	zcp->zc_word[0] = BE_64(tmp.zc_word[0]);
 	zcp->zc_word[1] = BE_64(tmp.zc_word[1]);
@@ -57,24 +66,24 @@ zio_checksum_SHA256(const void *buf, uint64_t size,
 
 /*ARGSUSED*/
 void
-zio_checksum_SHA512_native(const void *buf, uint64_t size,
+abd_checksum_SHA512_native(abd_t *abd, uint64_t size,
     const void *ctx_template, zio_cksum_t *zcp)
 {
 	SHA2_CTX	ctx;
 
 	SHA2Init(SHA512_256, &ctx);
-	SHA2Update(&ctx, buf, size);
+	(void) abd_iterate_func(abd, 0, size, sha_incremental, &ctx);
 	SHA2Final(zcp, &ctx);
 }
 
 /*ARGSUSED*/
 void
-zio_checksum_SHA512_byteswap(const void *buf, uint64_t size,
+abd_checksum_SHA512_byteswap(abd_t *abd, uint64_t size,
     const void *ctx_template, zio_cksum_t *zcp)
 {
 	zio_cksum_t	tmp;
 
-	zio_checksum_SHA512_native(buf, size, ctx_template, &tmp);
+	abd_checksum_SHA512_native(abd, size, ctx_template, &tmp);
 	zcp->zc_word[0] = BSWAP_64(tmp.zc_word[0]);
 	zcp->zc_word[1] = BSWAP_64(tmp.zc_word[1]);
 	zcp->zc_word[2] = BSWAP_64(tmp.zc_word[2]);
diff --git a/module/zfs/skein_zfs.c b/module/zfs/skein_zfs.c
index 659234039..8deb84b26 100644
--- a/module/zfs/skein_zfs.c
+++ b/module/zfs/skein_zfs.c
@@ -20,42 +20,52 @@
  */
 /*
  * Copyright 2013 Saso Kiselkov.  All rights reserved.
+ * Copyright (c) 2016 by Delphix. All rights reserved.
  */
 #include <sys/zfs_context.h>
 #include <sys/zio.h>
 #include <sys/skein.h>
 
+#include <sys/abd.h>
+
+static int
+skein_incremental(void *buf, size_t size, void *arg)
+{
+	Skein_512_Ctxt_t *ctx = arg;
+	(void) Skein_512_Update(ctx, buf, size);
+	return (0);
+}
 /*
  * Computes a native 256-bit skein MAC checksum. Please note that this
  * function requires the presence of a ctx_template that should be allocated
- * using zio_checksum_skein_tmpl_init.
+ * using abd_checksum_skein_tmpl_init.
  */
 /*ARGSUSED*/
 void
-zio_checksum_skein_native(const void *buf, uint64_t size,
+abd_checksum_skein_native(abd_t *abd, uint64_t size,
     const void *ctx_template, zio_cksum_t *zcp)
 {
 	Skein_512_Ctxt_t	ctx;
 
 	ASSERT(ctx_template != NULL);
 	bcopy(ctx_template, &ctx, sizeof (ctx));
-	(void) Skein_512_Update(&ctx, buf, size);
+	(void) abd_iterate_func(abd, 0, size, skein_incremental, &ctx);
 	(void) Skein_512_Final(&ctx, (uint8_t *)zcp);
 	bzero(&ctx, sizeof (ctx));
 }
 
 /*
- * Byteswapped version of zio_checksum_skein_native. This just invokes
+ * Byteswapped version of abd_checksum_skein_native. This just invokes
  * the native checksum function and byteswaps the resulting checksum (since
  * skein is internally endian-insensitive).
  */
 void
-zio_checksum_skein_byteswap(const void *buf, uint64_t size,
+abd_checksum_skein_byteswap(abd_t *abd, uint64_t size,
     const void *ctx_template, zio_cksum_t *zcp)
 {
 	zio_cksum_t	tmp;
 
-	zio_checksum_skein_native(buf, size, ctx_template, &tmp);
+	abd_checksum_skein_native(abd, size, ctx_template, &tmp);
 	zcp->zc_word[0] = BSWAP_64(tmp.zc_word[0]);
 	zcp->zc_word[1] = BSWAP_64(tmp.zc_word[1]);
 	zcp->zc_word[2] = BSWAP_64(tmp.zc_word[2]);
@@ -67,7 +77,7 @@ zio_checksum_skein_byteswap(const void *buf, uint64_t size,
  * computations and returns a pointer to it.
  */
 void *
-zio_checksum_skein_tmpl_init(const zio_cksum_salt_t *salt)
+abd_checksum_skein_tmpl_init(const zio_cksum_salt_t *salt)
 {
 	Skein_512_Ctxt_t	*ctx;
 
@@ -82,7 +92,7 @@ zio_checksum_skein_tmpl_init(const zio_cksum_salt_t *salt)
  * zio_checksum_skein_tmpl_init.
  */
 void
-zio_checksum_skein_tmpl_free(void *ctx_template)
+abd_checksum_skein_tmpl_free(void *ctx_template)
 {
 	Skein_512_Ctxt_t	*ctx = ctx_template;
 
diff --git a/module/zfs/spa.c b/module/zfs/spa.c
index 05e15a2e6..c55225a10 100644
--- a/module/zfs/spa.c
+++ b/module/zfs/spa.c
@@ -1963,6 +1963,7 @@ spa_load_verify_done(zio_t *zio)
 	int error = zio->io_error;
 	spa_t *spa = zio->io_spa;
 
+	abd_free(zio->io_abd);
 	if (error) {
 		if ((BP_GET_LEVEL(bp) != 0 || DMU_OT_IS_METADATA(type)) &&
 		    type != DMU_OT_INTENT_LOG)
@@ -1970,7 +1971,6 @@ spa_load_verify_done(zio_t *zio)
 		else
 			atomic_inc_64(&sle->sle_data_count);
 	}
-	zio_data_buf_free(zio->io_data, zio->io_size);
 
 	mutex_enter(&spa->spa_scrub_lock);
 	spa->spa_scrub_inflight--;
@@ -1993,7 +1993,6 @@ spa_load_verify_cb(spa_t *spa, zilog_t *zilog, const blkptr_t *bp,
 {
 	zio_t *rio;
 	size_t size;
-	void *data;
 
 	if (bp == NULL || BP_IS_HOLE(bp) || BP_IS_EMBEDDED(bp))
 		return (0);
@@ -2004,12 +2003,11 @@ spa_load_verify_cb(spa_t *spa, zilog_t *zilog, const blkptr_t *bp,
 	 */
 	if (!spa_load_verify_metadata)
 		return (0);
-	if (BP_GET_BUFC_TYPE(bp) == ARC_BUFC_DATA && !spa_load_verify_data)
+	if (!BP_IS_METADATA(bp) && !spa_load_verify_data)
 		return (0);
 
 	rio = arg;
 	size = BP_GET_PSIZE(bp);
-	data = zio_data_buf_alloc(size);
 
 	mutex_enter(&spa->spa_scrub_lock);
 	while (spa->spa_scrub_inflight >= spa_load_verify_maxinflight)
@@ -2017,7 +2015,7 @@ spa_load_verify_cb(spa_t *spa, zilog_t *zilog, const blkptr_t *bp,
 	spa->spa_scrub_inflight++;
 	mutex_exit(&spa->spa_scrub_lock);
 
-	zio_nowait(zio_read(rio, spa, bp, data, size,
+	zio_nowait(zio_read(rio, spa, bp, abd_alloc_for_io(size, B_FALSE), size,
 	    spa_load_verify_done, rio->io_private, ZIO_PRIORITY_SCRUB,
 	    ZIO_FLAG_SPECULATIVE | ZIO_FLAG_CANFAIL |
 	    ZIO_FLAG_SCRUB | ZIO_FLAG_RAW, zb));
diff --git a/module/zfs/vdev.c b/module/zfs/vdev.c
index db44d2ae1..8fc1a8d28 100644
--- a/module/zfs/vdev.c
+++ b/module/zfs/vdev.c
@@ -43,6 +43,7 @@
 #include <sys/arc.h>
 #include <sys/zil.h>
 #include <sys/dsl_scan.h>
+#include <sys/abd.h>
 #include <sys/zvol.h>
 #include <sys/zfs_ratelimit.h>
 
@@ -999,16 +1000,16 @@ vdev_probe_done(zio_t *zio)
 			vps->vps_readable = 1;
 		if (zio->io_error == 0 && spa_writeable(spa)) {
 			zio_nowait(zio_write_phys(vd->vdev_probe_zio, vd,
-			    zio->io_offset, zio->io_size, zio->io_data,
+			    zio->io_offset, zio->io_size, zio->io_abd,
 			    ZIO_CHECKSUM_OFF, vdev_probe_done, vps,
 			    ZIO_PRIORITY_SYNC_WRITE, vps->vps_flags, B_TRUE));
 		} else {
-			zio_buf_free(zio->io_data, zio->io_size);
+			abd_free(zio->io_abd);
 		}
 	} else if (zio->io_type == ZIO_TYPE_WRITE) {
 		if (zio->io_error == 0)
 			vps->vps_writeable = 1;
-		zio_buf_free(zio->io_data, zio->io_size);
+		abd_free(zio->io_abd);
 	} else if (zio->io_type == ZIO_TYPE_NULL) {
 		zio_t *pio;
 		zio_link_t *zl;
@@ -1126,8 +1127,8 @@ vdev_probe(vdev_t *vd, zio_t *zio)
 	for (l = 1; l < VDEV_LABELS; l++) {
 		zio_nowait(zio_read_phys(pio, vd,
 		    vdev_label_offset(vd->vdev_psize, l,
-		    offsetof(vdev_label_t, vl_pad2)),
-		    VDEV_PAD_SIZE, zio_buf_alloc(VDEV_PAD_SIZE),
+		    offsetof(vdev_label_t, vl_pad2)), VDEV_PAD_SIZE,
+		    abd_alloc_for_io(VDEV_PAD_SIZE, B_TRUE),
 		    ZIO_CHECKSUM_OFF, vdev_probe_done, vps,
 		    ZIO_PRIORITY_SYNC_READ, vps->vps_flags, B_TRUE));
 	}
diff --git a/module/zfs/vdev_cache.c b/module/zfs/vdev_cache.c
index 321ea4a2f..ec701097b 100644
--- a/module/zfs/vdev_cache.c
+++ b/module/zfs/vdev_cache.c
@@ -23,7 +23,7 @@
  * Use is subject to license terms.
  */
 /*
- * Copyright (c) 2013, 2015 by Delphix. All rights reserved.
+ * Copyright (c) 2013, 2016 by Delphix. All rights reserved.
  */
 
 #include <sys/zfs_context.h>
@@ -31,6 +31,7 @@
 #include <sys/vdev_impl.h>
 #include <sys/zio.h>
 #include <sys/kstat.h>
+#include <sys/abd.h>
 
 /*
  * Virtual device read-ahead caching.
@@ -136,12 +137,12 @@ static void
 vdev_cache_evict(vdev_cache_t *vc, vdev_cache_entry_t *ve)
 {
 	ASSERT(MUTEX_HELD(&vc->vc_lock));
-	ASSERT(ve->ve_fill_io == NULL);
-	ASSERT(ve->ve_data != NULL);
+	ASSERT3P(ve->ve_fill_io, ==, NULL);
+	ASSERT3P(ve->ve_abd, !=, NULL);
 
 	avl_remove(&vc->vc_lastused_tree, ve);
 	avl_remove(&vc->vc_offset_tree, ve);
-	zio_buf_free(ve->ve_data, VCBS);
+	abd_free(ve->ve_abd);
 	kmem_free(ve, sizeof (vdev_cache_entry_t));
 }
 
@@ -171,14 +172,14 @@ vdev_cache_allocate(zio_t *zio)
 		ve = avl_first(&vc->vc_lastused_tree);
 		if (ve->ve_fill_io != NULL)
 			return (NULL);
-		ASSERT(ve->ve_hits != 0);
+		ASSERT3U(ve->ve_hits, !=, 0);
 		vdev_cache_evict(vc, ve);
 	}
 
 	ve = kmem_zalloc(sizeof (vdev_cache_entry_t), KM_SLEEP);
 	ve->ve_offset = offset;
 	ve->ve_lastused = ddi_get_lbolt();
-	ve->ve_data = zio_buf_alloc(VCBS);
+	ve->ve_abd = abd_alloc_for_io(VCBS, B_TRUE);
 
 	avl_add(&vc->vc_offset_tree, ve);
 	avl_add(&vc->vc_lastused_tree, ve);
@@ -192,7 +193,7 @@ vdev_cache_hit(vdev_cache_t *vc, vdev_cache_entry_t *ve, zio_t *zio)
 	uint64_t cache_phase = P2PHASE(zio->io_offset, VCBS);
 
 	ASSERT(MUTEX_HELD(&vc->vc_lock));
-	ASSERT(ve->ve_fill_io == NULL);
+	ASSERT3P(ve->ve_fill_io, ==, NULL);
 
 	if (ve->ve_lastused != ddi_get_lbolt()) {
 		avl_remove(&vc->vc_lastused_tree, ve);
@@ -201,7 +202,7 @@ vdev_cache_hit(vdev_cache_t *vc, vdev_cache_entry_t *ve, zio_t *zio)
 	}
 
 	ve->ve_hits++;
-	bcopy(ve->ve_data + cache_phase, zio->io_data, zio->io_size);
+	abd_copy_off(zio->io_abd, ve->ve_abd, 0, cache_phase, zio->io_size);
 }
 
 /*
@@ -216,16 +217,16 @@ vdev_cache_fill(zio_t *fio)
 	zio_t *pio;
 	zio_link_t *zl;
 
-	ASSERT(fio->io_size == VCBS);
+	ASSERT3U(fio->io_size, ==, VCBS);
 
 	/*
 	 * Add data to the cache.
 	 */
 	mutex_enter(&vc->vc_lock);
 
-	ASSERT(ve->ve_fill_io == fio);
-	ASSERT(ve->ve_offset == fio->io_offset);
-	ASSERT(ve->ve_data == fio->io_data);
+	ASSERT3P(ve->ve_fill_io, ==, fio);
+	ASSERT3U(ve->ve_offset, ==, fio->io_offset);
+	ASSERT3P(ve->ve_abd, ==, fio->io_abd);
 
 	ve->ve_fill_io = NULL;
 
@@ -256,7 +257,7 @@ vdev_cache_read(zio_t *zio)
 	zio_t *fio;
 	ASSERTV(uint64_t cache_phase = P2PHASE(zio->io_offset, VCBS));
 
-	ASSERT(zio->io_type == ZIO_TYPE_READ);
+	ASSERT3U(zio->io_type, ==, ZIO_TYPE_READ);
 
 	if (zio->io_flags & ZIO_FLAG_DONT_CACHE)
 		return (B_FALSE);
@@ -270,7 +271,7 @@ vdev_cache_read(zio_t *zio)
 	if (P2BOUNDARY(zio->io_offset, zio->io_size, VCBS))
 		return (B_FALSE);
 
-	ASSERT(cache_phase + zio->io_size <= VCBS);
+	ASSERT3U(cache_phase + zio->io_size, <=, VCBS);
 
 	mutex_enter(&vc->vc_lock);
 
@@ -309,7 +310,7 @@ vdev_cache_read(zio_t *zio)
 	}
 
 	fio = zio_vdev_delegated_io(zio->io_vd, cache_offset,
-	    ve->ve_data, VCBS, ZIO_TYPE_READ, ZIO_PRIORITY_NOW,
+	    ve->ve_abd, VCBS, ZIO_TYPE_READ, ZIO_PRIORITY_NOW,
 	    ZIO_FLAG_DONT_CACHE, vdev_cache_fill, ve);
 
 	ve->ve_fill_io = fio;
@@ -337,7 +338,7 @@ vdev_cache_write(zio_t *zio)
 	uint64_t max_offset = P2ROUNDUP(io_end, VCBS);
 	avl_index_t where;
 
-	ASSERT(zio->io_type == ZIO_TYPE_WRITE);
+	ASSERT3U(zio->io_type, ==, ZIO_TYPE_WRITE);
 
 	mutex_enter(&vc->vc_lock);
 
@@ -354,8 +355,8 @@ vdev_cache_write(zio_t *zio)
 		if (ve->ve_fill_io != NULL) {
 			ve->ve_missed_update = 1;
 		} else {
-			bcopy((char *)zio->io_data + start - io_start,
-			    ve->ve_data + start - ve->ve_offset, end - start);
+			abd_copy_off(ve->ve_abd, zio->io_abd, start - io_start,
+			    start - ve->ve_offset, end - start);
 		}
 		ve = AVL_NEXT(&vc->vc_offset_tree, ve);
 	}
diff --git a/module/zfs/vdev_disk.c b/module/zfs/vdev_disk.c
index ce65760ee..67759d021 100644
--- a/module/zfs/vdev_disk.c
+++ b/module/zfs/vdev_disk.c
@@ -30,6 +30,7 @@
 #include <sys/spa.h>
 #include <sys/vdev_disk.h>
 #include <sys/vdev_impl.h>
+#include <sys/abd.h>
 #include <sys/fs/zfs.h>
 #include <sys/zio.h>
 #include <sys/sunldi.h>
@@ -42,6 +43,7 @@ static void *zfs_vdev_holder = VDEV_HOLDER;
  */
 typedef struct dio_request {
 	zio_t			*dr_zio;	/* Parent ZIO */
+	void			*dr_loanbuf;	/* borrowed abd buffer */
 	atomic_t		dr_ref;		/* References */
 	int			dr_error;	/* Bio error */
 	int			dr_bio_count;	/* Count of bio's */
@@ -402,6 +404,7 @@ vdev_disk_dio_put(dio_request_t *dr)
 	 */
 	if (rc == 0) {
 		zio_t *zio = dr->dr_zio;
+		void *loanbuf = dr->dr_loanbuf;
 		int error = dr->dr_error;
 
 		vdev_disk_dio_free(dr);
@@ -411,6 +414,15 @@ vdev_disk_dio_put(dio_request_t *dr)
 			ASSERT3S(zio->io_error, >=, 0);
 			if (zio->io_error)
 				vdev_disk_error(zio);
+			/* ABD placeholder */
+			if (loanbuf != NULL) {
+				if (zio->io_type == ZIO_TYPE_READ) {
+					abd_copy_from_buf(zio->io_abd, loanbuf,
+					    zio->io_size);
+				}
+				zio_buf_free(loanbuf, zio->io_size);
+			}
+
 			zio_delay_interrupt(zio);
 		}
 	}
@@ -547,7 +559,30 @@ retry:
 	 * their volume block size to match the maximum request size and
 	 * the common case will be one bio per vdev IO request.
 	 */
-	bio_ptr    = kbuf_ptr;
+	if (zio != NULL) {
+		abd_t *abd = zio->io_abd;
+
+		/*
+		 * ABD placeholder
+		 * We can't use abd_borrow_buf routines here since our
+		 * completion context is interrupt and abd refcounts
+		 * take a mutex (in debug mode).
+		 */
+		if (abd_is_linear(abd)) {
+			bio_ptr = abd_to_buf(abd);
+			dr->dr_loanbuf = NULL;
+		} else {
+			bio_ptr = zio_buf_alloc(zio->io_size);
+			dr->dr_loanbuf = bio_ptr;
+			if (zio->io_type != ZIO_TYPE_READ)
+				abd_copy_to_buf(bio_ptr, abd, zio->io_size);
+
+		}
+	} else {
+		bio_ptr = kbuf_ptr;
+		dr->dr_loanbuf = NULL;
+	}
+
 	bio_offset = kbuf_offset;
 	bio_size   = kbuf_size;
 	for (i = 0; i <= dr->dr_bio_count; i++) {
@@ -562,6 +597,8 @@ retry:
 		 * are needed we allocate a larger dio and warn the user.
 		 */
 		if (dr->dr_bio_count == i) {
+			if (dr->dr_loanbuf)
+				zio_buf_free(dr->dr_loanbuf, zio->io_size);
 			vdev_disk_dio_free(dr);
 			bio_count *= 2;
 			goto retry;
@@ -571,6 +608,8 @@ retry:
 		dr->dr_bio[i] = bio_alloc(GFP_NOIO,
 		    MIN(bio_nr_pages(bio_ptr, bio_size), BIO_MAX_PAGES));
 		if (unlikely(dr->dr_bio[i] == NULL)) {
+			if (dr->dr_loanbuf)
+				zio_buf_free(dr->dr_loanbuf, zio->io_size);
 			vdev_disk_dio_free(dr);
 			return (ENOMEM);
 		}
@@ -730,7 +769,7 @@ vdev_disk_io_start(zio_t *zio)
 	}
 
 	zio->io_target_timestamp = zio_handle_io_delay(zio);
-	error = __vdev_disk_physio(vd->vd_bdev, zio, zio->io_data,
+	error = __vdev_disk_physio(vd->vd_bdev, zio, NULL,
 	    zio->io_size, zio->io_offset, rw, flags);
 	if (error) {
 		zio->io_error = error;
diff --git a/module/zfs/vdev_file.c b/module/zfs/vdev_file.c
index a0a23598b..c78f2f421 100644
--- a/module/zfs/vdev_file.c
+++ b/module/zfs/vdev_file.c
@@ -31,6 +31,7 @@
 #include <sys/zio.h>
 #include <sys/fs/zfs.h>
 #include <sys/fm/fs/zfs.h>
+#include <sys/abd.h>
 
 /*
  * Virtual device vector for files.
@@ -150,11 +151,21 @@ vdev_file_io_strategy(void *arg)
 	vdev_t *vd = zio->io_vd;
 	vdev_file_t *vf = vd->vdev_tsd;
 	ssize_t resid;
+	void *buf;
+
+	if (zio->io_type == ZIO_TYPE_READ)
+		buf = abd_borrow_buf(zio->io_abd, zio->io_size);
+	else
+		buf = abd_borrow_buf_copy(zio->io_abd, zio->io_size);
 
 	zio->io_error = vn_rdwr(zio->io_type == ZIO_TYPE_READ ?
-	    UIO_READ : UIO_WRITE, vf->vf_vnode, zio->io_data,
-	    zio->io_size, zio->io_offset, UIO_SYSSPACE,
-	    0, RLIM64_INFINITY, kcred, &resid);
+	    UIO_READ : UIO_WRITE, vf->vf_vnode, buf, zio->io_size,
+	    zio->io_offset, UIO_SYSSPACE, 0, RLIM64_INFINITY, kcred, &resid);
+
+	if (zio->io_type == ZIO_TYPE_READ)
+		abd_return_buf_copy(zio->io_abd, buf, zio->io_size);
+	else
+		abd_return_buf(zio->io_abd, buf, zio->io_size);
 
 	if (resid != 0 && zio->io_error == 0)
 		zio->io_error = SET_ERROR(ENOSPC);
diff --git a/module/zfs/vdev_label.c b/module/zfs/vdev_label.c
index 4edbfa41e..7a3a0e8a0 100644
--- a/module/zfs/vdev_label.c
+++ b/module/zfs/vdev_label.c
@@ -145,6 +145,7 @@
 #include <sys/metaslab.h>
 #include <sys/zio.h>
 #include <sys/dsl_scan.h>
+#include <sys/abd.h>
 #include <sys/fs/zfs.h>
 
 /*
@@ -178,7 +179,7 @@ vdev_label_number(uint64_t psize, uint64_t offset)
 }
 
 static void
-vdev_label_read(zio_t *zio, vdev_t *vd, int l, void *buf, uint64_t offset,
+vdev_label_read(zio_t *zio, vdev_t *vd, int l, abd_t *buf, uint64_t offset,
 	uint64_t size, zio_done_func_t *done, void *private, int flags)
 {
 	ASSERT(spa_config_held(zio->io_spa, SCL_STATE_ALL, RW_WRITER) ==
@@ -192,7 +193,7 @@ vdev_label_read(zio_t *zio, vdev_t *vd, int l, void *buf, uint64_t offset,
 }
 
 static void
-vdev_label_write(zio_t *zio, vdev_t *vd, int l, void *buf, uint64_t offset,
+vdev_label_write(zio_t *zio, vdev_t *vd, int l, abd_t *buf, uint64_t offset,
 	uint64_t size, zio_done_func_t *done, void *private, int flags)
 {
 	ASSERT(spa_config_held(zio->io_spa, SCL_ALL, RW_WRITER) == SCL_ALL ||
@@ -587,6 +588,7 @@ vdev_label_read_config(vdev_t *vd, uint64_t txg)
 	spa_t *spa = vd->vdev_spa;
 	nvlist_t *config = NULL;
 	vdev_phys_t *vp;
+	abd_t *vp_abd;
 	zio_t *zio;
 	uint64_t best_txg = 0;
 	int error = 0;
@@ -599,7 +601,8 @@ vdev_label_read_config(vdev_t *vd, uint64_t txg)
 	if (!vdev_readable(vd))
 		return (NULL);
 
-	vp = zio_buf_alloc(sizeof (vdev_phys_t));
+	vp_abd = abd_alloc_linear(sizeof (vdev_phys_t), B_TRUE);
+	vp = abd_to_buf(vp_abd);
 
 retry:
 	for (l = 0; l < VDEV_LABELS; l++) {
@@ -607,7 +610,7 @@ retry:
 
 		zio = zio_root(spa, NULL, NULL, flags);
 
-		vdev_label_read(zio, vd, l, vp,
+		vdev_label_read(zio, vd, l, vp_abd,
 		    offsetof(vdev_label_t, vl_vdev_phys),
 		    sizeof (vdev_phys_t), NULL, NULL, flags);
 
@@ -646,7 +649,7 @@ retry:
 		goto retry;
 	}
 
-	zio_buf_free(vp, sizeof (vdev_phys_t));
+	abd_free(vp_abd);
 
 	return (config);
 }
@@ -782,8 +785,10 @@ vdev_label_init(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason)
 	spa_t *spa = vd->vdev_spa;
 	nvlist_t *label;
 	vdev_phys_t *vp;
-	char *pad2;
+	abd_t *vp_abd;
+	abd_t *pad2;
 	uberblock_t *ub;
+	abd_t *ub_abd;
 	zio_t *zio;
 	char *buf;
 	size_t buflen;
@@ -867,8 +872,9 @@ vdev_label_init(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason)
 	/*
 	 * Initialize its label.
 	 */
-	vp = zio_buf_alloc(sizeof (vdev_phys_t));
-	bzero(vp, sizeof (vdev_phys_t));
+	vp_abd = abd_alloc_linear(sizeof (vdev_phys_t), B_TRUE);
+	abd_zero(vp_abd, sizeof (vdev_phys_t));
+	vp = abd_to_buf(vp_abd);
 
 	/*
 	 * Generate a label describing the pool and our top-level vdev.
@@ -928,7 +934,7 @@ vdev_label_init(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason)
 	error = nvlist_pack(label, &buf, &buflen, NV_ENCODE_XDR, KM_SLEEP);
 	if (error != 0) {
 		nvlist_free(label);
-		zio_buf_free(vp, sizeof (vdev_phys_t));
+		abd_free(vp_abd);
 		/* EFAULT means nvlist_pack ran out of room */
 		return (error == EFAULT ? ENAMETOOLONG : EINVAL);
 	}
@@ -936,14 +942,15 @@ vdev_label_init(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason)
 	/*
 	 * Initialize uberblock template.
 	 */
-	ub = zio_buf_alloc(VDEV_UBERBLOCK_RING);
-	bzero(ub, VDEV_UBERBLOCK_RING);
-	*ub = spa->spa_uberblock;
+	ub_abd = abd_alloc_linear(VDEV_UBERBLOCK_RING, B_TRUE);
+	abd_zero(ub_abd, VDEV_UBERBLOCK_RING);
+	abd_copy_from_buf(ub_abd, &spa->spa_uberblock, sizeof (uberblock_t));
+	ub = abd_to_buf(ub_abd);
 	ub->ub_txg = 0;
 
 	/* Initialize the 2nd padding area. */
-	pad2 = zio_buf_alloc(VDEV_PAD_SIZE);
-	bzero(pad2, VDEV_PAD_SIZE);
+	pad2 = abd_alloc_for_io(VDEV_PAD_SIZE, B_TRUE);
+	abd_zero(pad2, VDEV_PAD_SIZE);
 
 	/*
 	 * Write everything in parallel.
@@ -953,7 +960,7 @@ retry:
 
 	for (l = 0; l < VDEV_LABELS; l++) {
 
-		vdev_label_write(zio, vd, l, vp,
+		vdev_label_write(zio, vd, l, vp_abd,
 		    offsetof(vdev_label_t, vl_vdev_phys),
 		    sizeof (vdev_phys_t), NULL, NULL, flags);
 
@@ -966,7 +973,7 @@ retry:
 		    offsetof(vdev_label_t, vl_pad2),
 		    VDEV_PAD_SIZE, NULL, NULL, flags);
 
-		vdev_label_write(zio, vd, l, ub,
+		vdev_label_write(zio, vd, l, ub_abd,
 		    offsetof(vdev_label_t, vl_uberblock),
 		    VDEV_UBERBLOCK_RING, NULL, NULL, flags);
 	}
@@ -979,9 +986,9 @@ retry:
 	}
 
 	nvlist_free(label);
-	zio_buf_free(pad2, VDEV_PAD_SIZE);
-	zio_buf_free(ub, VDEV_UBERBLOCK_RING);
-	zio_buf_free(vp, sizeof (vdev_phys_t));
+	abd_free(pad2);
+	abd_free(ub_abd);
+	abd_free(vp_abd);
 
 	/*
 	 * If this vdev hasn't been previously identified as a spare, then we
@@ -1039,7 +1046,7 @@ vdev_uberblock_load_done(zio_t *zio)
 	vdev_t *vd = zio->io_vd;
 	spa_t *spa = zio->io_spa;
 	zio_t *rio = zio->io_private;
-	uberblock_t *ub = zio->io_data;
+	uberblock_t *ub = abd_to_buf(zio->io_abd);
 	struct ubl_cbdata *cbp = rio->io_private;
 
 	ASSERT3U(zio->io_size, ==, VDEV_UBERBLOCK_SIZE(vd));
@@ -1060,7 +1067,7 @@ vdev_uberblock_load_done(zio_t *zio)
 		mutex_exit(&rio->io_lock);
 	}
 
-	zio_buf_free(zio->io_data, zio->io_size);
+	abd_free(zio->io_abd);
 }
 
 static void
@@ -1076,8 +1083,8 @@ vdev_uberblock_load_impl(zio_t *zio, vdev_t *vd, int flags,
 		for (l = 0; l < VDEV_LABELS; l++) {
 			for (n = 0; n < VDEV_UBERBLOCK_COUNT(vd); n++) {
 				vdev_label_read(zio, vd, l,
-				    zio_buf_alloc(VDEV_UBERBLOCK_SIZE(vd)),
-				    VDEV_UBERBLOCK_OFFSET(vd, n),
+				    abd_alloc_linear(VDEV_UBERBLOCK_SIZE(vd),
+				    B_TRUE), VDEV_UBERBLOCK_OFFSET(vd, n),
 				    VDEV_UBERBLOCK_SIZE(vd),
 				    vdev_uberblock_load_done, zio, flags);
 			}
@@ -1144,7 +1151,7 @@ vdev_uberblock_sync_done(zio_t *zio)
 static void
 vdev_uberblock_sync(zio_t *zio, uberblock_t *ub, vdev_t *vd, int flags)
 {
-	uberblock_t *ubbuf;
+	abd_t *ub_abd;
 	int c, l, n;
 
 	for (c = 0; c < vd->vdev_children; c++)
@@ -1158,17 +1165,18 @@ vdev_uberblock_sync(zio_t *zio, uberblock_t *ub, vdev_t *vd, int flags)
 
 	n = ub->ub_txg & (VDEV_UBERBLOCK_COUNT(vd) - 1);
 
-	ubbuf = zio_buf_alloc(VDEV_UBERBLOCK_SIZE(vd));
-	bzero(ubbuf, VDEV_UBERBLOCK_SIZE(vd));
-	*ubbuf = *ub;
+	/* Copy the uberblock_t into the ABD */
+	ub_abd = abd_alloc_for_io(VDEV_UBERBLOCK_SIZE(vd), B_TRUE);
+	abd_zero(ub_abd, VDEV_UBERBLOCK_SIZE(vd));
+	abd_copy_from_buf(ub_abd, ub, sizeof (uberblock_t));
 
 	for (l = 0; l < VDEV_LABELS; l++)
-		vdev_label_write(zio, vd, l, ubbuf,
+		vdev_label_write(zio, vd, l, ub_abd,
 		    VDEV_UBERBLOCK_OFFSET(vd, n), VDEV_UBERBLOCK_SIZE(vd),
 		    vdev_uberblock_sync_done, zio->io_private,
 		    flags | ZIO_FLAG_DONT_PROPAGATE);
 
-	zio_buf_free(ubbuf, VDEV_UBERBLOCK_SIZE(vd));
+	abd_free(ub_abd);
 }
 
 /* Sync the uberblocks to all vdevs in svd[] */
@@ -1245,6 +1253,7 @@ vdev_label_sync(zio_t *zio, vdev_t *vd, int l, uint64_t txg, int flags)
 {
 	nvlist_t *label;
 	vdev_phys_t *vp;
+	abd_t *vp_abd;
 	char *buf;
 	size_t buflen;
 	int c;
@@ -1263,15 +1272,16 @@ vdev_label_sync(zio_t *zio, vdev_t *vd, int l, uint64_t txg, int flags)
 	 */
 	label = spa_config_generate(vd->vdev_spa, vd, txg, B_FALSE);
 
-	vp = zio_buf_alloc(sizeof (vdev_phys_t));
-	bzero(vp, sizeof (vdev_phys_t));
+	vp_abd = abd_alloc_linear(sizeof (vdev_phys_t), B_TRUE);
+	abd_zero(vp_abd, sizeof (vdev_phys_t));
+	vp = abd_to_buf(vp_abd);
 
 	buf = vp->vp_nvlist;
 	buflen = sizeof (vp->vp_nvlist);
 
 	if (!nvlist_pack(label, &buf, &buflen, NV_ENCODE_XDR, KM_SLEEP)) {
 		for (; l < VDEV_LABELS; l += 2) {
-			vdev_label_write(zio, vd, l, vp,
+			vdev_label_write(zio, vd, l, vp_abd,
 			    offsetof(vdev_label_t, vl_vdev_phys),
 			    sizeof (vdev_phys_t),
 			    vdev_label_sync_done, zio->io_private,
@@ -1279,7 +1289,7 @@ vdev_label_sync(zio_t *zio, vdev_t *vd, int l, uint64_t txg, int flags)
 		}
 	}
 
-	zio_buf_free(vp, sizeof (vdev_phys_t));
+	abd_free(vp_abd);
 	nvlist_free(label);
 }
 
diff --git a/module/zfs/vdev_mirror.c b/module/zfs/vdev_mirror.c
index 780311195..2b9081168 100644
--- a/module/zfs/vdev_mirror.c
+++ b/module/zfs/vdev_mirror.c
@@ -31,6 +31,7 @@
 #include <sys/spa.h>
 #include <sys/vdev_impl.h>
 #include <sys/zio.h>
+#include <sys/abd.h>
 #include <sys/fs/zfs.h>
 
 /*
@@ -272,13 +273,13 @@ vdev_mirror_scrub_done(zio_t *zio)
 		while ((pio = zio_walk_parents(zio, &zl)) != NULL) {
 			mutex_enter(&pio->io_lock);
 			ASSERT3U(zio->io_size, >=, pio->io_size);
-			bcopy(zio->io_data, pio->io_data, pio->io_size);
+			abd_copy(pio->io_abd, zio->io_abd, pio->io_size);
 			mutex_exit(&pio->io_lock);
 		}
 		mutex_exit(&zio->io_lock);
 	}
 
-	zio_buf_free(zio->io_data, zio->io_size);
+	abd_free(zio->io_abd);
 
 	mc->mc_error = zio->io_error;
 	mc->mc_tried = 1;
@@ -433,7 +434,8 @@ vdev_mirror_io_start(zio_t *zio)
 				mc = &mm->mm_child[c];
 				zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
 				    mc->mc_vd, mc->mc_offset,
-				    zio_buf_alloc(zio->io_size), zio->io_size,
+				    abd_alloc_sametype(zio->io_abd,
+				    zio->io_size), zio->io_size,
 				    zio->io_type, zio->io_priority, 0,
 				    vdev_mirror_scrub_done, mc));
 			}
@@ -458,7 +460,7 @@ vdev_mirror_io_start(zio_t *zio)
 	while (children--) {
 		mc = &mm->mm_child[c];
 		zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
-		    mc->mc_vd, mc->mc_offset, zio->io_data, zio->io_size,
+		    mc->mc_vd, mc->mc_offset, zio->io_abd, zio->io_size,
 		    zio->io_type, zio->io_priority, 0,
 		    vdev_mirror_child_done, mc));
 		c++;
@@ -543,7 +545,7 @@ vdev_mirror_io_done(zio_t *zio)
 		mc = &mm->mm_child[c];
 		zio_vdev_io_redone(zio);
 		zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
-		    mc->mc_vd, mc->mc_offset, zio->io_data, zio->io_size,
+		    mc->mc_vd, mc->mc_offset, zio->io_abd, zio->io_size,
 		    ZIO_TYPE_READ, zio->io_priority, 0,
 		    vdev_mirror_child_done, mc));
 		return;
@@ -584,7 +586,7 @@ vdev_mirror_io_done(zio_t *zio)
 
 			zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
 			    mc->mc_vd, mc->mc_offset,
-			    zio->io_data, zio->io_size,
+			    zio->io_abd, zio->io_size,
 			    ZIO_TYPE_WRITE, ZIO_PRIORITY_ASYNC_WRITE,
 			    ZIO_FLAG_IO_REPAIR | (unexpected_errors ?
 			    ZIO_FLAG_SELF_HEAL : 0), NULL, NULL));
diff --git a/module/zfs/vdev_queue.c b/module/zfs/vdev_queue.c
index 8f394eef5..91ef106b4 100644
--- a/module/zfs/vdev_queue.c
+++ b/module/zfs/vdev_queue.c
@@ -37,6 +37,7 @@
 #include <sys/spa.h>
 #include <sys/spa_impl.h>
 #include <sys/kstat.h>
+#include <sys/abd.h>
 
 /*
  * ZFS I/O Scheduler
@@ -496,12 +497,12 @@ vdev_queue_agg_io_done(zio_t *aio)
 		zio_t *pio;
 		zio_link_t *zl = NULL;
 		while ((pio = zio_walk_parents(aio, &zl)) != NULL) {
-			bcopy((char *)aio->io_data + (pio->io_offset -
-			    aio->io_offset), pio->io_data, pio->io_size);
+			abd_copy_off(pio->io_abd, aio->io_abd,
+			    0, pio->io_offset - aio->io_offset, pio->io_size);
 		}
 	}
 
-	zio_buf_free(aio->io_data, aio->io_size);
+	abd_free(aio->io_abd);
 }
 
 /*
@@ -523,7 +524,7 @@ vdev_queue_aggregate(vdev_queue_t *vq, zio_t *zio)
 	boolean_t stretch = B_FALSE;
 	avl_tree_t *t = vdev_queue_type_tree(vq, zio->io_type);
 	enum zio_flag flags = zio->io_flags & ZIO_FLAG_AGG_INHERIT;
-	void *buf;
+	abd_t *abd;
 
 	limit = MAX(MIN(zfs_vdev_aggregation_limit,
 	    spa_maxblocksize(vq->vq_vdev->vdev_spa)), 0);
@@ -626,12 +627,12 @@ vdev_queue_aggregate(vdev_queue_t *vq, zio_t *zio)
 	size = IO_SPAN(first, last);
 	ASSERT3U(size, <=, limit);
 
-	buf = zio_buf_alloc_flags(size, KM_NOSLEEP);
-	if (buf == NULL)
+	abd = abd_alloc_for_io(size, B_TRUE);
+	if (abd == NULL)
 		return (NULL);
 
 	aio = zio_vdev_delegated_io(first->io_vd, first->io_offset,
-	    buf, size, first->io_type, zio->io_priority,
+	    abd, size, first->io_type, zio->io_priority,
 	    flags | ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_QUEUE,
 	    vdev_queue_agg_io_done, NULL);
 	aio->io_timestamp = first->io_timestamp;
@@ -644,12 +645,11 @@ vdev_queue_aggregate(vdev_queue_t *vq, zio_t *zio)
 
 		if (dio->io_flags & ZIO_FLAG_NODATA) {
 			ASSERT3U(dio->io_type, ==, ZIO_TYPE_WRITE);
-			bzero((char *)aio->io_data + (dio->io_offset -
-			    aio->io_offset), dio->io_size);
+			abd_zero_off(aio->io_abd,
+			    dio->io_offset - aio->io_offset, dio->io_size);
 		} else if (dio->io_type == ZIO_TYPE_WRITE) {
-			bcopy(dio->io_data, (char *)aio->io_data +
-			    (dio->io_offset - aio->io_offset),
-			    dio->io_size);
+			abd_copy_off(aio->io_abd, dio->io_abd,
+			    dio->io_offset - aio->io_offset, 0, dio->io_size);
 		}
 
 		zio_add_child(dio, aio);
diff --git a/module/zfs/vdev_raidz.c b/module/zfs/vdev_raidz.c
index d1b415367..d08fdab13 100644
--- a/module/zfs/vdev_raidz.c
+++ b/module/zfs/vdev_raidz.c
@@ -30,6 +30,7 @@
 #include <sys/vdev_impl.h>
 #include <sys/zio.h>
 #include <sys/zio_checksum.h>
+#include <sys/abd.h>
 #include <sys/fs/zfs.h>
 #include <sys/fm/fs/zfs.h>
 #include <sys/vdev_raidz.h>
@@ -136,7 +137,7 @@ vdev_raidz_map_free(raidz_map_t *rm)
 	size_t size;
 
 	for (c = 0; c < rm->rm_firstdatacol; c++) {
-		zio_buf_free(rm->rm_col[c].rc_data, rm->rm_col[c].rc_size);
+		abd_free(rm->rm_col[c].rc_abd);
 
 		if (rm->rm_col[c].rc_gdata != NULL)
 			zio_buf_free(rm->rm_col[c].rc_gdata,
@@ -144,11 +145,13 @@ vdev_raidz_map_free(raidz_map_t *rm)
 	}
 
 	size = 0;
-	for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++)
+	for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) {
+		abd_put(rm->rm_col[c].rc_abd);
 		size += rm->rm_col[c].rc_size;
+	}
 
-	if (rm->rm_datacopy != NULL)
-		zio_buf_free(rm->rm_datacopy, size);
+	if (rm->rm_abd_copy != NULL)
+		abd_free(rm->rm_abd_copy);
 
 	kmem_free(rm, offsetof(raidz_map_t, rm_col[rm->rm_scols]));
 }
@@ -185,7 +188,7 @@ vdev_raidz_cksum_finish(zio_cksum_report_t *zcr, const void *good_data)
 	size_t x;
 
 	const char *good = NULL;
-	const char *bad = rm->rm_col[c].rc_data;
+	char *bad;
 
 	if (good_data == NULL) {
 		zfs_ereport_finish_checksum(zcr, NULL, NULL, B_FALSE);
@@ -199,8 +202,9 @@ vdev_raidz_cksum_finish(zio_cksum_report_t *zcr, const void *good_data)
 		 * data never changes for a given logical ZIO)
 		 */
 		if (rm->rm_col[0].rc_gdata == NULL) {
-			char *bad_parity[VDEV_RAIDZ_MAXPARITY];
+			abd_t *bad_parity[VDEV_RAIDZ_MAXPARITY];
 			char *buf;
+			int offset;
 
 			/*
 			 * Set up the rm_col[]s to generate the parity for
@@ -208,15 +212,20 @@ vdev_raidz_cksum_finish(zio_cksum_report_t *zcr, const void *good_data)
 			 * replacing them with buffers to hold the result.
 			 */
 			for (x = 0; x < rm->rm_firstdatacol; x++) {
-				bad_parity[x] = rm->rm_col[x].rc_data;
-				rm->rm_col[x].rc_data = rm->rm_col[x].rc_gdata =
+				bad_parity[x] = rm->rm_col[x].rc_abd;
+				rm->rm_col[x].rc_gdata =
 				    zio_buf_alloc(rm->rm_col[x].rc_size);
+				rm->rm_col[x].rc_abd =
+				    abd_get_from_buf(rm->rm_col[x].rc_gdata,
+				    rm->rm_col[x].rc_size);
 			}
 
 			/* fill in the data columns from good_data */
 			buf = (char *)good_data;
 			for (; x < rm->rm_cols; x++) {
-				rm->rm_col[x].rc_data = buf;
+				abd_put(rm->rm_col[x].rc_abd);
+				rm->rm_col[x].rc_abd = abd_get_from_buf(buf,
+				    rm->rm_col[x].rc_size);
 				buf += rm->rm_col[x].rc_size;
 			}
 
@@ -226,13 +235,17 @@ vdev_raidz_cksum_finish(zio_cksum_report_t *zcr, const void *good_data)
 			vdev_raidz_generate_parity(rm);
 
 			/* restore everything back to its original state */
-			for (x = 0; x < rm->rm_firstdatacol; x++)
-				rm->rm_col[x].rc_data = bad_parity[x];
+			for (x = 0; x < rm->rm_firstdatacol; x++) {
+				abd_put(rm->rm_col[x].rc_abd);
+				rm->rm_col[x].rc_abd = bad_parity[x];
+			}
 
-			buf = rm->rm_datacopy;
+			offset = 0;
 			for (x = rm->rm_firstdatacol; x < rm->rm_cols; x++) {
-				rm->rm_col[x].rc_data = buf;
-				buf += rm->rm_col[x].rc_size;
+				abd_put(rm->rm_col[x].rc_abd);
+				rm->rm_col[x].rc_abd = abd_get_offset(
+				    rm->rm_abd_copy, offset);
+				offset += rm->rm_col[x].rc_size;
 			}
 		}
 
@@ -246,8 +259,10 @@ vdev_raidz_cksum_finish(zio_cksum_report_t *zcr, const void *good_data)
 			good += rm->rm_col[x].rc_size;
 	}
 
+	bad = abd_borrow_buf_copy(rm->rm_col[c].rc_abd, rm->rm_col[c].rc_size);
 	/* we drop the ereport if it ends up that the data was good */
 	zfs_ereport_finish_checksum(zcr, good, bad, B_TRUE);
+	abd_return_buf(rm->rm_col[c].rc_abd, bad, rm->rm_col[c].rc_size);
 }
 
 /*
@@ -260,7 +275,7 @@ static void
 vdev_raidz_cksum_report(zio_t *zio, zio_cksum_report_t *zcr, void *arg)
 {
 	size_t c = (size_t)(uintptr_t)arg;
-	caddr_t buf;
+	size_t offset;
 
 	raidz_map_t *rm = zio->io_vsd;
 	size_t size;
@@ -274,7 +289,7 @@ vdev_raidz_cksum_report(zio_t *zio, zio_cksum_report_t *zcr, void *arg)
 	rm->rm_reports++;
 	ASSERT3U(rm->rm_reports, >, 0);
 
-	if (rm->rm_datacopy != NULL)
+	if (rm->rm_abd_copy != NULL)
 		return;
 
 	/*
@@ -290,17 +305,20 @@ vdev_raidz_cksum_report(zio_t *zio, zio_cksum_report_t *zcr, void *arg)
 	for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++)
 		size += rm->rm_col[c].rc_size;
 
-	buf = rm->rm_datacopy = zio_buf_alloc(size);
+	rm->rm_abd_copy =
+	    abd_alloc_sametype(rm->rm_col[rm->rm_firstdatacol].rc_abd, size);
 
-	for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) {
+	for (offset = 0, c = rm->rm_firstdatacol; c < rm->rm_cols; c++) {
 		raidz_col_t *col = &rm->rm_col[c];
+		abd_t *tmp = abd_get_offset(rm->rm_abd_copy, offset);
 
-		bcopy(col->rc_data, buf, col->rc_size);
-		col->rc_data = buf;
+		abd_copy(tmp, col->rc_abd, col->rc_size);
+		abd_put(col->rc_abd);
+		col->rc_abd = tmp;
 
-		buf += col->rc_size;
+		offset += col->rc_size;
 	}
-	ASSERT3P(buf - (caddr_t)rm->rm_datacopy, ==, size);
+	ASSERT3U(offset, ==, size);
 }
 
 static const zio_vsd_ops_t vdev_raidz_vsd_ops = {
@@ -329,6 +347,7 @@ vdev_raidz_map_alloc(zio_t *zio, uint64_t unit_shift, uint64_t dcols,
 	/* The starting byte offset on each child vdev. */
 	uint64_t o = (b / dcols) << unit_shift;
 	uint64_t q, r, c, bc, col, acols, scols, coff, devidx, asize, tot;
+	uint64_t off = 0;
 
 	/*
 	 * "Quotient": The number of data sectors for this stripe on all but
@@ -373,7 +392,7 @@ vdev_raidz_map_alloc(zio_t *zio, uint64_t unit_shift, uint64_t dcols,
 	rm->rm_missingdata = 0;
 	rm->rm_missingparity = 0;
 	rm->rm_firstdatacol = nparity;
-	rm->rm_datacopy = NULL;
+	rm->rm_abd_copy = NULL;
 	rm->rm_reports = 0;
 	rm->rm_freed = 0;
 	rm->rm_ecksuminjected = 0;
@@ -389,7 +408,7 @@ vdev_raidz_map_alloc(zio_t *zio, uint64_t unit_shift, uint64_t dcols,
 		}
 		rm->rm_col[c].rc_devidx = col;
 		rm->rm_col[c].rc_offset = coff;
-		rm->rm_col[c].rc_data = NULL;
+		rm->rm_col[c].rc_abd = NULL;
 		rm->rm_col[c].rc_gdata = NULL;
 		rm->rm_col[c].rc_error = 0;
 		rm->rm_col[c].rc_tried = 0;
@@ -412,13 +431,16 @@ vdev_raidz_map_alloc(zio_t *zio, uint64_t unit_shift, uint64_t dcols,
 	ASSERT3U(rm->rm_nskip, <=, nparity);
 
 	for (c = 0; c < rm->rm_firstdatacol; c++)
-		rm->rm_col[c].rc_data = zio_buf_alloc(rm->rm_col[c].rc_size);
+		rm->rm_col[c].rc_abd =
+		    abd_alloc_linear(rm->rm_col[c].rc_size, B_TRUE);
 
-	rm->rm_col[c].rc_data = zio->io_data;
+	rm->rm_col[c].rc_abd = abd_get_offset(zio->io_abd, 0);
+	off = rm->rm_col[c].rc_size;
 
-	for (c = c + 1; c < acols; c++)
-		rm->rm_col[c].rc_data = (char *)rm->rm_col[c - 1].rc_data +
-		    rm->rm_col[c - 1].rc_size;
+	for (c = c + 1; c < acols; c++) {
+		rm->rm_col[c].rc_abd = abd_get_offset(zio->io_abd, off);
+		off += rm->rm_col[c].rc_size;
+	}
 
 	/*
 	 * If all data stored spans all columns, there's a danger that parity
@@ -464,29 +486,84 @@ vdev_raidz_map_alloc(zio_t *zio, uint64_t unit_shift, uint64_t dcols,
 	return (rm);
 }
 
+struct pqr_struct {
+	uint64_t *p;
+	uint64_t *q;
+	uint64_t *r;
+};
+
+static int
+vdev_raidz_p_func(void *buf, size_t size, void *private)
+{
+	struct pqr_struct *pqr = private;
+	const uint64_t *src = buf;
+	int i, cnt = size / sizeof (src[0]);
+
+	ASSERT(pqr->p && !pqr->q && !pqr->r);
+
+	for (i = 0; i < cnt; i++, src++, pqr->p++)
+		*pqr->p ^= *src;
+
+	return (0);
+}
+
+static int
+vdev_raidz_pq_func(void *buf, size_t size, void *private)
+{
+	struct pqr_struct *pqr = private;
+	const uint64_t *src = buf;
+	uint64_t mask;
+	int i, cnt = size / sizeof (src[0]);
+
+	ASSERT(pqr->p && pqr->q && !pqr->r);
+
+	for (i = 0; i < cnt; i++, src++, pqr->p++, pqr->q++) {
+		*pqr->p ^= *src;
+		VDEV_RAIDZ_64MUL_2(*pqr->q, mask);
+		*pqr->q ^= *src;
+	}
+
+	return (0);
+}
+
+static int
+vdev_raidz_pqr_func(void *buf, size_t size, void *private)
+{
+	struct pqr_struct *pqr = private;
+	const uint64_t *src = buf;
+	uint64_t mask;
+	int i, cnt = size / sizeof (src[0]);
+
+	ASSERT(pqr->p && pqr->q && pqr->r);
+
+	for (i = 0; i < cnt; i++, src++, pqr->p++, pqr->q++, pqr->r++) {
+		*pqr->p ^= *src;
+		VDEV_RAIDZ_64MUL_2(*pqr->q, mask);
+		*pqr->q ^= *src;
+		VDEV_RAIDZ_64MUL_4(*pqr->r, mask);
+		*pqr->r ^= *src;
+	}
+
+	return (0);
+}
+
 static void
 vdev_raidz_generate_parity_p(raidz_map_t *rm)
 {
-	uint64_t *p, *src, pcount, ccount, i;
+	uint64_t *p;
 	int c;
-
-	pcount = rm->rm_col[VDEV_RAIDZ_P].rc_size / sizeof (src[0]);
+	abd_t *src;
 
 	for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) {
-		src = rm->rm_col[c].rc_data;
-		p = rm->rm_col[VDEV_RAIDZ_P].rc_data;
-		ccount = rm->rm_col[c].rc_size / sizeof (src[0]);
+		src = rm->rm_col[c].rc_abd;
+		p = abd_to_buf(rm->rm_col[VDEV_RAIDZ_P].rc_abd);
 
 		if (c == rm->rm_firstdatacol) {
-			ASSERT(ccount == pcount);
-			for (i = 0; i < ccount; i++, src++, p++) {
-				*p = *src;
-			}
+			abd_copy_to_buf(p, src, rm->rm_col[c].rc_size);
 		} else {
-			ASSERT(ccount <= pcount);
-			for (i = 0; i < ccount; i++, src++, p++) {
-				*p ^= *src;
-			}
+			struct pqr_struct pqr = { p, NULL, NULL };
+			(void) abd_iterate_func(src, 0, rm->rm_col[c].rc_size,
+			    vdev_raidz_p_func, &pqr);
 		}
 	}
 }
@@ -494,50 +571,43 @@ vdev_raidz_generate_parity_p(raidz_map_t *rm)
 static void
 vdev_raidz_generate_parity_pq(raidz_map_t *rm)
 {
-	uint64_t *p, *q, *src, pcnt, ccnt, mask, i;
+	uint64_t *p, *q, pcnt, ccnt, mask, i;
 	int c;
+	abd_t *src;
 
-	pcnt = rm->rm_col[VDEV_RAIDZ_P].rc_size / sizeof (src[0]);
+	pcnt = rm->rm_col[VDEV_RAIDZ_P].rc_size / sizeof (p[0]);
 	ASSERT(rm->rm_col[VDEV_RAIDZ_P].rc_size ==
 	    rm->rm_col[VDEV_RAIDZ_Q].rc_size);
 
 	for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) {
-		src = rm->rm_col[c].rc_data;
-		p = rm->rm_col[VDEV_RAIDZ_P].rc_data;
-		q = rm->rm_col[VDEV_RAIDZ_Q].rc_data;
+		src = rm->rm_col[c].rc_abd;
+		p = abd_to_buf(rm->rm_col[VDEV_RAIDZ_P].rc_abd);
+		q = abd_to_buf(rm->rm_col[VDEV_RAIDZ_Q].rc_abd);
 
-		ccnt = rm->rm_col[c].rc_size / sizeof (src[0]);
+		ccnt = rm->rm_col[c].rc_size / sizeof (p[0]);
 
 		if (c == rm->rm_firstdatacol) {
-			ASSERT(ccnt == pcnt || ccnt == 0);
-			for (i = 0; i < ccnt; i++, src++, p++, q++) {
-				*p = *src;
-				*q = *src;
-			}
-			for (; i < pcnt; i++, src++, p++, q++) {
-				*p = 0;
-				*q = 0;
-			}
+			abd_copy_to_buf(p, src, rm->rm_col[c].rc_size);
+			(void) memcpy(q, p, rm->rm_col[c].rc_size);
 		} else {
-			ASSERT(ccnt <= pcnt);
-
-			/*
-			 * Apply the algorithm described above by multiplying
-			 * the previous result and adding in the new value.
-			 */
-			for (i = 0; i < ccnt; i++, src++, p++, q++) {
-				*p ^= *src;
+			struct pqr_struct pqr = { p, q, NULL };
+			(void) abd_iterate_func(src, 0, rm->rm_col[c].rc_size,
+			    vdev_raidz_pq_func, &pqr);
+		}
 
-				VDEV_RAIDZ_64MUL_2(*q, mask);
-				*q ^= *src;
+		if (c == rm->rm_firstdatacol) {
+			for (i = ccnt; i < pcnt; i++) {
+				p[i] = 0;
+				q[i] = 0;
 			}
+		} else {
 
 			/*
 			 * Treat short columns as though they are full of 0s.
 			 * Note that there's therefore nothing needed for P.
 			 */
-			for (; i < pcnt; i++, q++) {
-				VDEV_RAIDZ_64MUL_2(*q, mask);
+			for (i = ccnt; i < pcnt; i++) {
+				VDEV_RAIDZ_64MUL_2(q[i], mask);
 			}
 		}
 	}
@@ -546,59 +616,48 @@ vdev_raidz_generate_parity_pq(raidz_map_t *rm)
 static void
 vdev_raidz_generate_parity_pqr(raidz_map_t *rm)
 {
-	uint64_t *p, *q, *r, *src, pcnt, ccnt, mask, i;
+	uint64_t *p, *q, *r, pcnt, ccnt, mask, i;
 	int c;
+	abd_t *src;
 
-	pcnt = rm->rm_col[VDEV_RAIDZ_P].rc_size / sizeof (src[0]);
+	pcnt = rm->rm_col[VDEV_RAIDZ_P].rc_size / sizeof (p[0]);
 	ASSERT(rm->rm_col[VDEV_RAIDZ_P].rc_size ==
 	    rm->rm_col[VDEV_RAIDZ_Q].rc_size);
 	ASSERT(rm->rm_col[VDEV_RAIDZ_P].rc_size ==
 	    rm->rm_col[VDEV_RAIDZ_R].rc_size);
 
 	for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) {
-		src = rm->rm_col[c].rc_data;
-		p = rm->rm_col[VDEV_RAIDZ_P].rc_data;
-		q = rm->rm_col[VDEV_RAIDZ_Q].rc_data;
-		r = rm->rm_col[VDEV_RAIDZ_R].rc_data;
+		src = rm->rm_col[c].rc_abd;
+		p = abd_to_buf(rm->rm_col[VDEV_RAIDZ_P].rc_abd);
+		q = abd_to_buf(rm->rm_col[VDEV_RAIDZ_Q].rc_abd);
+		r = abd_to_buf(rm->rm_col[VDEV_RAIDZ_R].rc_abd);
 
-		ccnt = rm->rm_col[c].rc_size / sizeof (src[0]);
+		ccnt = rm->rm_col[c].rc_size / sizeof (p[0]);
 
 		if (c == rm->rm_firstdatacol) {
-			ASSERT(ccnt == pcnt || ccnt == 0);
-			for (i = 0; i < ccnt; i++, src++, p++, q++, r++) {
-				*p = *src;
-				*q = *src;
-				*r = *src;
-			}
-			for (; i < pcnt; i++, src++, p++, q++, r++) {
-				*p = 0;
-				*q = 0;
-				*r = 0;
-			}
+			abd_copy_to_buf(p, src, rm->rm_col[c].rc_size);
+			(void) memcpy(q, p, rm->rm_col[c].rc_size);
+			(void) memcpy(r, p, rm->rm_col[c].rc_size);
 		} else {
-			ASSERT(ccnt <= pcnt);
-
-			/*
-			 * Apply the algorithm described above by multiplying
-			 * the previous result and adding in the new value.
-			 */
-			for (i = 0; i < ccnt; i++, src++, p++, q++, r++) {
-				*p ^= *src;
-
-				VDEV_RAIDZ_64MUL_2(*q, mask);
-				*q ^= *src;
+			struct pqr_struct pqr = { p, q, r };
+			(void) abd_iterate_func(src, 0, rm->rm_col[c].rc_size,
+			    vdev_raidz_pqr_func, &pqr);
+		}
 
-				VDEV_RAIDZ_64MUL_4(*r, mask);
-				*r ^= *src;
+		if (c == rm->rm_firstdatacol) {
+			for (i = ccnt; i < pcnt; i++) {
+				p[i] = 0;
+				q[i] = 0;
+				r[i] = 0;
 			}
-
+		} else {
 			/*
 			 * Treat short columns as though they are full of 0s.
 			 * Note that there's therefore nothing needed for P.
 			 */
-			for (; i < pcnt; i++, q++, r++) {
-				VDEV_RAIDZ_64MUL_2(*q, mask);
-				VDEV_RAIDZ_64MUL_4(*r, mask);
+			for (i = ccnt; i < pcnt; i++) {
+				VDEV_RAIDZ_64MUL_2(q[i], mask);
+				VDEV_RAIDZ_64MUL_4(r[i], mask);
 			}
 		}
 	}
@@ -630,40 +689,159 @@ vdev_raidz_generate_parity(raidz_map_t *rm)
 	}
 }
 
+/* ARGSUSED */
+static int
+vdev_raidz_reconst_p_func(void *dbuf, void *sbuf, size_t size, void *private)
+{
+	uint64_t *dst = dbuf;
+	uint64_t *src = sbuf;
+	int cnt = size / sizeof (src[0]);
+	int i;
+
+	for (i = 0; i < cnt; i++) {
+		dst[i] ^= src[i];
+	}
+
+	return (0);
+}
+
+/* ARGSUSED */
+static int
+vdev_raidz_reconst_q_pre_func(void *dbuf, void *sbuf, size_t size,
+    void *private)
+{
+	uint64_t *dst = dbuf;
+	uint64_t *src = sbuf;
+	uint64_t mask;
+	int cnt = size / sizeof (dst[0]);
+	int i;
+
+	for (i = 0; i < cnt; i++, dst++, src++) {
+		VDEV_RAIDZ_64MUL_2(*dst, mask);
+		*dst ^= *src;
+	}
+
+	return (0);
+}
+
+/* ARGSUSED */
+static int
+vdev_raidz_reconst_q_pre_tail_func(void *buf, size_t size, void *private)
+{
+	uint64_t *dst = buf;
+	uint64_t mask;
+	int cnt = size / sizeof (dst[0]);
+	int i;
+
+	for (i = 0; i < cnt; i++, dst++) {
+		/* same operation as vdev_raidz_reconst_q_pre_func() on dst */
+		VDEV_RAIDZ_64MUL_2(*dst, mask);
+	}
+
+	return (0);
+}
+
+struct reconst_q_struct {
+	uint64_t *q;
+	int exp;
+};
+
+static int
+vdev_raidz_reconst_q_post_func(void *buf, size_t size, void *private)
+{
+	struct reconst_q_struct *rq = private;
+	uint64_t *dst = buf;
+	int cnt = size / sizeof (dst[0]);
+	int i;
+
+	for (i = 0; i < cnt; i++, dst++, rq->q++) {
+		int j;
+		uint8_t *b;
+
+		*dst ^= *rq->q;
+		for (j = 0, b = (uint8_t *)dst; j < 8; j++, b++) {
+			*b = vdev_raidz_exp2(*b, rq->exp);
+		}
+	}
+
+	return (0);
+}
+
+struct reconst_pq_struct {
+	uint8_t *p;
+	uint8_t *q;
+	uint8_t *pxy;
+	uint8_t *qxy;
+	int aexp;
+	int bexp;
+};
+
+static int
+vdev_raidz_reconst_pq_func(void *xbuf, void *ybuf, size_t size, void *private)
+{
+	struct reconst_pq_struct *rpq = private;
+	uint8_t *xd = xbuf;
+	uint8_t *yd = ybuf;
+	int i;
+
+	for (i = 0; i < size;
+	    i++, rpq->p++, rpq->q++, rpq->pxy++, rpq->qxy++, xd++, yd++) {
+		*xd = vdev_raidz_exp2(*rpq->p ^ *rpq->pxy, rpq->aexp) ^
+		    vdev_raidz_exp2(*rpq->q ^ *rpq->qxy, rpq->bexp);
+		*yd = *rpq->p ^ *rpq->pxy ^ *xd;
+	}
+
+	return (0);
+}
+
+static int
+vdev_raidz_reconst_pq_tail_func(void *xbuf, size_t size, void *private)
+{
+	struct reconst_pq_struct *rpq = private;
+	uint8_t *xd = xbuf;
+	int i;
+
+	for (i = 0; i < size;
+	    i++, rpq->p++, rpq->q++, rpq->pxy++, rpq->qxy++, xd++) {
+		/* same operation as vdev_raidz_reconst_pq_func() on xd */
+		*xd = vdev_raidz_exp2(*rpq->p ^ *rpq->pxy, rpq->aexp) ^
+		    vdev_raidz_exp2(*rpq->q ^ *rpq->qxy, rpq->bexp);
+	}
+
+	return (0);
+}
+
 static int
 vdev_raidz_reconstruct_p(raidz_map_t *rm, int *tgts, int ntgts)
 {
-	uint64_t *dst, *src, xcount, ccount, count, i;
 	int x = tgts[0];
 	int c;
+	abd_t *dst, *src;
 
 	ASSERT(ntgts == 1);
 	ASSERT(x >= rm->rm_firstdatacol);
 	ASSERT(x < rm->rm_cols);
 
-	xcount = rm->rm_col[x].rc_size / sizeof (src[0]);
-	ASSERT(xcount <= rm->rm_col[VDEV_RAIDZ_P].rc_size / sizeof (src[0]));
-	ASSERT(xcount > 0);
+	ASSERT(rm->rm_col[x].rc_size <= rm->rm_col[VDEV_RAIDZ_P].rc_size);
+	ASSERT(rm->rm_col[x].rc_size > 0);
 
-	src = rm->rm_col[VDEV_RAIDZ_P].rc_data;
-	dst = rm->rm_col[x].rc_data;
-	for (i = 0; i < xcount; i++, dst++, src++) {
-		*dst = *src;
-	}
+	src = rm->rm_col[VDEV_RAIDZ_P].rc_abd;
+	dst = rm->rm_col[x].rc_abd;
+
+	abd_copy_from_buf(dst, abd_to_buf(src), rm->rm_col[x].rc_size);
 
 	for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) {
-		src = rm->rm_col[c].rc_data;
-		dst = rm->rm_col[x].rc_data;
+		uint64_t size = MIN(rm->rm_col[x].rc_size,
+		    rm->rm_col[c].rc_size);
+
+		src = rm->rm_col[c].rc_abd;
+		dst = rm->rm_col[x].rc_abd;
 
 		if (c == x)
 			continue;
 
-		ccount = rm->rm_col[c].rc_size / sizeof (src[0]);
-		count = MIN(ccount, xcount);
-
-		for (i = 0; i < count; i++, dst++, src++) {
-			*dst ^= *src;
-		}
+		(void) abd_iterate_func2(dst, src, 0, 0, size,
+		    vdev_raidz_reconst_p_func, NULL);
 	}
 
 	return (1 << VDEV_RAIDZ_P);
@@ -672,57 +850,46 @@ vdev_raidz_reconstruct_p(raidz_map_t *rm, int *tgts, int ntgts)
 static int
 vdev_raidz_reconstruct_q(raidz_map_t *rm, int *tgts, int ntgts)
 {
-	uint64_t *dst, *src, xcount, ccount, count, mask, i;
-	uint8_t *b;
 	int x = tgts[0];
-	int c, j, exp;
+	int c, exp;
+	abd_t *dst, *src;
+	struct reconst_q_struct rq;
 
 	ASSERT(ntgts == 1);
 
-	xcount = rm->rm_col[x].rc_size / sizeof (src[0]);
-	ASSERT(xcount <= rm->rm_col[VDEV_RAIDZ_Q].rc_size / sizeof (src[0]));
+	ASSERT(rm->rm_col[x].rc_size <= rm->rm_col[VDEV_RAIDZ_Q].rc_size);
 
 	for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) {
-		src = rm->rm_col[c].rc_data;
-		dst = rm->rm_col[x].rc_data;
-
-		if (c == x)
-			ccount = 0;
-		else
-			ccount = rm->rm_col[c].rc_size / sizeof (src[0]);
+		uint64_t size = (c == x) ? 0 : MIN(rm->rm_col[x].rc_size,
+		    rm->rm_col[c].rc_size);
 
-		count = MIN(ccount, xcount);
+		src = rm->rm_col[c].rc_abd;
+		dst = rm->rm_col[x].rc_abd;
 
 		if (c == rm->rm_firstdatacol) {
-			for (i = 0; i < count; i++, dst++, src++) {
-				*dst = *src;
-			}
-			for (; i < xcount; i++, dst++) {
-				*dst = 0;
-			}
+			abd_copy(dst, src, size);
+			if (rm->rm_col[x].rc_size > size)
+				abd_zero_off(dst, size,
+				    rm->rm_col[x].rc_size - size);
 
 		} else {
-			for (i = 0; i < count; i++, dst++, src++) {
-				VDEV_RAIDZ_64MUL_2(*dst, mask);
-				*dst ^= *src;
-			}
-
-			for (; i < xcount; i++, dst++) {
-				VDEV_RAIDZ_64MUL_2(*dst, mask);
-			}
+			ASSERT3U(size, <=, rm->rm_col[x].rc_size);
+			(void) abd_iterate_func2(dst, src, 0, 0, size,
+			    vdev_raidz_reconst_q_pre_func, NULL);
+			(void) abd_iterate_func(dst,
+			    size, rm->rm_col[x].rc_size - size,
+			    vdev_raidz_reconst_q_pre_tail_func, NULL);
 		}
 	}
 
-	src = rm->rm_col[VDEV_RAIDZ_Q].rc_data;
-	dst = rm->rm_col[x].rc_data;
+	src = rm->rm_col[VDEV_RAIDZ_Q].rc_abd;
+	dst = rm->rm_col[x].rc_abd;
 	exp = 255 - (rm->rm_cols - 1 - x);
+	rq.q = abd_to_buf(src);
+	rq.exp = exp;
 
-	for (i = 0; i < xcount; i++, dst++, src++) {
-		*dst ^= *src;
-		for (j = 0, b = (uint8_t *)dst; j < 8; j++, b++) {
-			*b = vdev_raidz_exp2(*b, exp);
-		}
-	}
+	(void) abd_iterate_func(dst, 0, rm->rm_col[x].rc_size,
+	    vdev_raidz_reconst_q_post_func, &rq);
 
 	return (1 << VDEV_RAIDZ_Q);
 }
@@ -730,11 +897,13 @@ vdev_raidz_reconstruct_q(raidz_map_t *rm, int *tgts, int ntgts)
 static int
 vdev_raidz_reconstruct_pq(raidz_map_t *rm, int *tgts, int ntgts)
 {
-	uint8_t *p, *q, *pxy, *qxy, *xd, *yd, tmp, a, b, aexp, bexp;
-	void *pdata, *qdata;
-	uint64_t xsize, ysize, i;
+	uint8_t *p, *q, *pxy, *qxy, tmp, a, b, aexp, bexp;
+	abd_t *pdata, *qdata;
+	uint64_t xsize, ysize;
 	int x = tgts[0];
 	int y = tgts[1];
+	abd_t *xd, *yd;
+	struct reconst_pq_struct rpq;
 
 	ASSERT(ntgts == 2);
 	ASSERT(x < y);
@@ -750,15 +919,15 @@ vdev_raidz_reconstruct_pq(raidz_map_t *rm, int *tgts, int ntgts)
 	 * parity so we make those columns appear to be full of zeros by
 	 * setting their lengths to zero.
 	 */
-	pdata = rm->rm_col[VDEV_RAIDZ_P].rc_data;
-	qdata = rm->rm_col[VDEV_RAIDZ_Q].rc_data;
+	pdata = rm->rm_col[VDEV_RAIDZ_P].rc_abd;
+	qdata = rm->rm_col[VDEV_RAIDZ_Q].rc_abd;
 	xsize = rm->rm_col[x].rc_size;
 	ysize = rm->rm_col[y].rc_size;
 
-	rm->rm_col[VDEV_RAIDZ_P].rc_data =
-	    zio_buf_alloc(rm->rm_col[VDEV_RAIDZ_P].rc_size);
-	rm->rm_col[VDEV_RAIDZ_Q].rc_data =
-	    zio_buf_alloc(rm->rm_col[VDEV_RAIDZ_Q].rc_size);
+	rm->rm_col[VDEV_RAIDZ_P].rc_abd =
+	    abd_alloc_linear(rm->rm_col[VDEV_RAIDZ_P].rc_size, B_TRUE);
+	rm->rm_col[VDEV_RAIDZ_Q].rc_abd =
+	    abd_alloc_linear(rm->rm_col[VDEV_RAIDZ_Q].rc_size, B_TRUE);
 	rm->rm_col[x].rc_size = 0;
 	rm->rm_col[y].rc_size = 0;
 
@@ -767,12 +936,12 @@ vdev_raidz_reconstruct_pq(raidz_map_t *rm, int *tgts, int ntgts)
 	rm->rm_col[x].rc_size = xsize;
 	rm->rm_col[y].rc_size = ysize;
 
-	p = pdata;
-	q = qdata;
-	pxy = rm->rm_col[VDEV_RAIDZ_P].rc_data;
-	qxy = rm->rm_col[VDEV_RAIDZ_Q].rc_data;
-	xd = rm->rm_col[x].rc_data;
-	yd = rm->rm_col[y].rc_data;
+	p = abd_to_buf(pdata);
+	q = abd_to_buf(qdata);
+	pxy = abd_to_buf(rm->rm_col[VDEV_RAIDZ_P].rc_abd);
+	qxy = abd_to_buf(rm->rm_col[VDEV_RAIDZ_Q].rc_abd);
+	xd = rm->rm_col[x].rc_abd;
+	yd = rm->rm_col[y].rc_abd;
 
 	/*
 	 * We now have:
@@ -796,24 +965,27 @@ vdev_raidz_reconstruct_pq(raidz_map_t *rm, int *tgts, int ntgts)
 	aexp = vdev_raidz_log2[vdev_raidz_exp2(a, tmp)];
 	bexp = vdev_raidz_log2[vdev_raidz_exp2(b, tmp)];
 
-	for (i = 0; i < xsize; i++, p++, q++, pxy++, qxy++, xd++, yd++) {
-		*xd = vdev_raidz_exp2(*p ^ *pxy, aexp) ^
-		    vdev_raidz_exp2(*q ^ *qxy, bexp);
+	ASSERT3U(xsize, >=, ysize);
+	rpq.p = p;
+	rpq.q = q;
+	rpq.pxy = pxy;
+	rpq.qxy = qxy;
+	rpq.aexp = aexp;
+	rpq.bexp = bexp;
 
-		if (i < ysize)
-			*yd = *p ^ *pxy ^ *xd;
-	}
+	(void) abd_iterate_func2(xd, yd, 0, 0, ysize,
+	    vdev_raidz_reconst_pq_func, &rpq);
+	(void) abd_iterate_func(xd, ysize, xsize - ysize,
+	    vdev_raidz_reconst_pq_tail_func, &rpq);
 
-	zio_buf_free(rm->rm_col[VDEV_RAIDZ_P].rc_data,
-	    rm->rm_col[VDEV_RAIDZ_P].rc_size);
-	zio_buf_free(rm->rm_col[VDEV_RAIDZ_Q].rc_data,
-	    rm->rm_col[VDEV_RAIDZ_Q].rc_size);
+	abd_free(rm->rm_col[VDEV_RAIDZ_P].rc_abd);
+	abd_free(rm->rm_col[VDEV_RAIDZ_Q].rc_abd);
 
 	/*
 	 * Restore the saved parity data.
 	 */
-	rm->rm_col[VDEV_RAIDZ_P].rc_data = pdata;
-	rm->rm_col[VDEV_RAIDZ_Q].rc_data = qdata;
+	rm->rm_col[VDEV_RAIDZ_P].rc_abd = pdata;
+	rm->rm_col[VDEV_RAIDZ_Q].rc_abd = qdata;
 
 	return ((1 << VDEV_RAIDZ_P) | (1 << VDEV_RAIDZ_Q));
 }
@@ -1131,7 +1303,7 @@ vdev_raidz_matrix_reconstruct(raidz_map_t *rm, int n, int nmissing,
 		c = used[i];
 		ASSERT3U(c, <, rm->rm_cols);
 
-		src = rm->rm_col[c].rc_data;
+		src = abd_to_buf(rm->rm_col[c].rc_abd);
 		ccount = rm->rm_col[c].rc_size;
 		for (j = 0; j < nmissing; j++) {
 			cc = missing[j] + rm->rm_firstdatacol;
@@ -1139,7 +1311,7 @@ vdev_raidz_matrix_reconstruct(raidz_map_t *rm, int n, int nmissing,
 			ASSERT3U(cc, <, rm->rm_cols);
 			ASSERT3U(cc, !=, c);
 
-			dst[j] = rm->rm_col[cc].rc_data;
+			dst[j] = abd_to_buf(rm->rm_col[cc].rc_abd);
 			dcount[j] = rm->rm_col[cc].rc_size;
 		}
 
@@ -1187,8 +1359,25 @@ vdev_raidz_reconstruct_general(raidz_map_t *rm, int *tgts, int ntgts)
 	uint8_t *invrows[VDEV_RAIDZ_MAXPARITY];
 	uint8_t *used;
 
+	abd_t **bufs = NULL;
+
 	int code = 0;
 
+	/*
+	 * Matrix reconstruction can't use scatter ABDs yet, so we allocate
+	 * temporary linear ABDs.
+	 */
+	if (!abd_is_linear(rm->rm_col[rm->rm_firstdatacol].rc_abd)) {
+		bufs = kmem_alloc(rm->rm_cols * sizeof (abd_t *), KM_PUSHPAGE);
+
+		for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) {
+			raidz_col_t *col = &rm->rm_col[c];
+
+			bufs[c] = col->rc_abd;
+			col->rc_abd = abd_alloc_linear(col->rc_size, B_TRUE);
+			abd_copy(col->rc_abd, bufs[c], col->rc_size);
+		}
+	}
 
 	n = rm->rm_cols - rm->rm_firstdatacol;
 
@@ -1275,6 +1464,20 @@ vdev_raidz_reconstruct_general(raidz_map_t *rm, int *tgts, int ntgts)
 
 	kmem_free(p, psize);
 
+	/*
+	 * copy back from temporary linear abds and free them
+	 */
+	if (bufs) {
+		for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) {
+			raidz_col_t *col = &rm->rm_col[c];
+
+			abd_copy(bufs[c], col->rc_abd, col->rc_size);
+			abd_free(col->rc_abd);
+			col->rc_abd = bufs[c];
+		}
+		kmem_free(bufs, rm->rm_cols * sizeof (abd_t *));
+	}
+
 	return (code);
 }
 
@@ -1321,7 +1524,6 @@ vdev_raidz_reconstruct(raidz_map_t *rm, const int *t, int nt)
 
 	dt = &tgts[nbadparity];
 
-
 	/* Reconstruct using the new math implementation */
 	ret = vdev_raidz_math_reconstruct(rm, parity_valid, dt, nbaddata);
 	if (ret != RAIDZ_ORIGINAL_IMPL)
@@ -1479,7 +1681,7 @@ vdev_raidz_io_start(zio_t *zio)
 			rc = &rm->rm_col[c];
 			cvd = vd->vdev_child[rc->rc_devidx];
 			zio_nowait(zio_vdev_child_io(zio, NULL, cvd,
-			    rc->rc_offset, rc->rc_data, rc->rc_size,
+			    rc->rc_offset, rc->rc_abd, rc->rc_size,
 			    zio->io_type, zio->io_priority, 0,
 			    vdev_raidz_child_done, rc));
 		}
@@ -1536,7 +1738,7 @@ vdev_raidz_io_start(zio_t *zio)
 		if (c >= rm->rm_firstdatacol || rm->rm_missingdata > 0 ||
 		    (zio->io_flags & (ZIO_FLAG_SCRUB | ZIO_FLAG_RESILVER))) {
 			zio_nowait(zio_vdev_child_io(zio, NULL, cvd,
-			    rc->rc_offset, rc->rc_data, rc->rc_size,
+			    rc->rc_offset, rc->rc_abd, rc->rc_size,
 			    zio->io_type, zio->io_priority, 0,
 			    vdev_raidz_child_done, rc));
 		}
@@ -1552,6 +1754,7 @@ vdev_raidz_io_start(zio_t *zio)
 static void
 raidz_checksum_error(zio_t *zio, raidz_col_t *rc, void *bad_data)
 {
+	void *buf;
 	vdev_t *vd = zio->io_vd->vdev_child[rc->rc_devidx];
 
 	if (!(zio->io_flags & ZIO_FLAG_SPECULATIVE)) {
@@ -1565,9 +1768,11 @@ raidz_checksum_error(zio_t *zio, raidz_col_t *rc, void *bad_data)
 		zbc.zbc_has_cksum = 0;
 		zbc.zbc_injected = rm->rm_ecksuminjected;
 
+		buf = abd_borrow_buf_copy(rc->rc_abd, rc->rc_size);
 		zfs_ereport_post_checksum(zio->io_spa, vd, zio,
-		    rc->rc_offset, rc->rc_size, rc->rc_data, bad_data,
+		    rc->rc_offset, rc->rc_size, buf, bad_data,
 		    &zbc);
+		abd_return_buf(rc->rc_abd, buf, rc->rc_size);
 	}
 }
 
@@ -1616,7 +1821,7 @@ raidz_parity_verify(zio_t *zio, raidz_map_t *rm)
 		if (!rc->rc_tried || rc->rc_error != 0)
 			continue;
 		orig[c] = zio_buf_alloc(rc->rc_size);
-		bcopy(rc->rc_data, orig[c], rc->rc_size);
+		abd_copy_to_buf(orig[c], rc->rc_abd, rc->rc_size);
 	}
 
 	vdev_raidz_generate_parity(rm);
@@ -1625,7 +1830,7 @@ raidz_parity_verify(zio_t *zio, raidz_map_t *rm)
 		rc = &rm->rm_col[c];
 		if (!rc->rc_tried || rc->rc_error != 0)
 			continue;
-		if (bcmp(orig[c], rc->rc_data, rc->rc_size) != 0) {
+		if (bcmp(orig[c], abd_to_buf(rc->rc_abd), rc->rc_size) != 0) {
 			raidz_checksum_error(zio, rc, orig[c]);
 			rc->rc_error = SET_ERROR(ECKSUM);
 			ret++;
@@ -1728,7 +1933,8 @@ vdev_raidz_combrec(zio_t *zio, int total_errors, int data_errors)
 				ASSERT3S(c, >=, 0);
 				ASSERT3S(c, <, rm->rm_cols);
 				rc = &rm->rm_col[c];
-				bcopy(rc->rc_data, orig[i], rc->rc_size);
+				abd_copy_to_buf(orig[i], rc->rc_abd,
+				    rc->rc_size);
 			}
 
 			/*
@@ -1758,7 +1964,8 @@ vdev_raidz_combrec(zio_t *zio, int total_errors, int data_errors)
 			for (i = 0; i < n; i++) {
 				c = tgts[i];
 				rc = &rm->rm_col[c];
-				bcopy(orig[i], rc->rc_data, rc->rc_size);
+				abd_copy_from_buf(rc->rc_abd, orig[i],
+				    rc->rc_size);
 			}
 
 			do {
@@ -1997,7 +2204,7 @@ vdev_raidz_io_done(zio_t *zio)
 				continue;
 			zio_nowait(zio_vdev_child_io(zio, NULL,
 			    vd->vdev_child[rc->rc_devidx],
-			    rc->rc_offset, rc->rc_data, rc->rc_size,
+			    rc->rc_offset, rc->rc_abd, rc->rc_size,
 			    zio->io_type, zio->io_priority, 0,
 			    vdev_raidz_child_done, rc));
 		} while (++c < rm->rm_cols);
@@ -2077,7 +2284,7 @@ done:
 				continue;
 
 			zio_nowait(zio_vdev_child_io(zio, NULL, cvd,
-			    rc->rc_offset, rc->rc_data, rc->rc_size,
+			    rc->rc_offset, rc->rc_abd, rc->rc_size,
 			    ZIO_TYPE_WRITE, ZIO_PRIORITY_ASYNC_WRITE,
 			    ZIO_FLAG_IO_REPAIR | (unexpected_errors ?
 			    ZIO_FLAG_SELF_HEAL : 0), NULL, NULL));
diff --git a/module/zfs/vdev_raidz_math.c b/module/zfs/vdev_raidz_math.c
index 33c05dadd..1e4bf8413 100644
--- a/module/zfs/vdev_raidz_math.c
+++ b/module/zfs/vdev_raidz_math.c
@@ -44,6 +44,16 @@ static raidz_impl_ops_t vdev_raidz_fastest_impl = {
 	.name = "fastest"
 };
 
+/* ABD BRINGUP -- not ready yet */
+#if 1
+#ifdef HAVE_SSSE3
+#undef HAVE_SSSE3
+#endif
+#ifdef HAVE_AVX2
+#undef HAVE_AVX2
+#endif
+#endif
+
 /* All compiled in implementations */
 const raidz_impl_ops_t *raidz_all_maths[] = {
 	&vdev_raidz_original_impl,
@@ -149,6 +159,8 @@ vdev_raidz_math_generate(raidz_map_t *rm)
 {
 	raidz_gen_f gen_parity = NULL;
 
+/* ABD Bringup -- vector code not ready */
+#if 0
 	switch (raidz_parity(rm)) {
 		case 1:
 			gen_parity = rm->rm_ops->gen[RAIDZ_GEN_P];
@@ -165,6 +177,7 @@ vdev_raidz_math_generate(raidz_map_t *rm)
 				raidz_parity(rm));
 			break;
 	}
+#endif
 
 	/* if method is NULL execute the original implementation */
 	if (gen_parity == NULL)
@@ -175,6 +188,8 @@ vdev_raidz_math_generate(raidz_map_t *rm)
 	return (0);
 }
 
+/* ABD Bringup -- vector code not ready */
+#if 0
 static raidz_rec_f
 reconstruct_fun_p_sel(raidz_map_t *rm, const int *parity_valid,
 	const int nbaddata)
@@ -229,6 +244,7 @@ reconstruct_fun_pqr_sel(raidz_map_t *rm, const int *parity_valid,
 	}
 	return ((raidz_rec_f) NULL);
 }
+#endif
 
 /*
  * Select data reconstruction method for raidz_map
@@ -242,6 +258,8 @@ vdev_raidz_math_reconstruct(raidz_map_t *rm, const int *parity_valid,
 {
 	raidz_rec_f rec_data = NULL;
 
+/* ABD Bringup -- vector code not ready */
+#if 0
 	switch (raidz_parity(rm)) {
 	case PARITY_P:
 		rec_data = reconstruct_fun_p_sel(rm, parity_valid, nbaddata);
@@ -257,6 +275,7 @@ vdev_raidz_math_reconstruct(raidz_map_t *rm, const int *parity_valid,
 		    raidz_parity(rm));
 		break;
 	}
+#endif
 
 	if (rec_data == NULL)
 		return (RAIDZ_ORIGINAL_IMPL);
@@ -471,13 +490,12 @@ vdev_raidz_math_init(void)
 	return;
 #endif
 
-	/* Fake an zio and run the benchmark on it */
+	/* Fake an zio and run the benchmark on a warmed up buffer */
 	bench_zio = kmem_zalloc(sizeof (zio_t), KM_SLEEP);
 	bench_zio->io_offset = 0;
 	bench_zio->io_size = BENCH_ZIO_SIZE; /* only data columns */
-	bench_zio->io_data = zio_data_buf_alloc(BENCH_ZIO_SIZE);
-	VERIFY(bench_zio->io_data);
-	memset(bench_zio->io_data, 0xAA, BENCH_ZIO_SIZE); /* warm up */
+	bench_zio->io_abd = abd_alloc_linear(BENCH_ZIO_SIZE, B_TRUE);
+	memset(abd_to_buf(bench_zio->io_abd), 0xAA, BENCH_ZIO_SIZE);
 
 	/* Benchmark parity generation methods */
 	for (fn = 0; fn < RAIDZ_GEN_NUM; fn++) {
@@ -501,7 +519,7 @@ vdev_raidz_math_init(void)
 	vdev_raidz_map_free(bench_rm);
 
 	/* cleanup the bench zio */
-	zio_data_buf_free(bench_zio->io_data, BENCH_ZIO_SIZE);
+	abd_free(bench_zio->io_abd);
 	kmem_free(bench_zio, sizeof (zio_t));
 
 	/* install kstats for all impl */
diff --git a/module/zfs/vdev_raidz_math_avx2.c b/module/zfs/vdev_raidz_math_avx2.c
index 90c94c77c..508c95f8d 100644
--- a/module/zfs/vdev_raidz_math_avx2.c
+++ b/module/zfs/vdev_raidz_math_avx2.c
@@ -21,7 +21,6 @@
 /*
  * Copyright (C) 2016 Gvozden Nešković. All rights reserved.
  */
-
 #include <sys/isa_defs.h>
 
 #if defined(__x86_64) && defined(HAVE_AVX2)
@@ -401,7 +400,12 @@ DEFINE_REC_METHODS(avx2);
 static boolean_t
 raidz_will_avx2_work(void)
 {
+/* ABD Bringup -- vector code not ready */
+#if 1
+	return (B_FALSE);
+#else
 	return (zfs_avx_available() && zfs_avx2_available());
+#endif
 }
 
 const raidz_impl_ops_t vdev_raidz_avx2_impl = {
diff --git a/module/zfs/vdev_raidz_math_impl.h b/module/zfs/vdev_raidz_math_impl.h
index 70257ee49..53800fd72 100644
--- a/module/zfs/vdev_raidz_math_impl.h
+++ b/module/zfs/vdev_raidz_math_impl.h
@@ -33,7 +33,8 @@
 #endif
 
 /* Calculate data offset in raidz column, offset is in bytes */
-#define	COL_OFF(col, off)	((v_t *)(((char *)(col)->rc_data) + (off)))
+/* ADB BRINGUP -- needs to be refactored for ABD */
+#define	COL_OFF(col, off)	((v_t *)(((char *)(col)->rc_abd) + (off)))
 
 /*
  * PARITY CALCULATION
@@ -83,6 +84,8 @@ raidz_generate_p_impl(raidz_map_t * const rm)
 	const size_t psize = raidz_big_size(rm);
 	const size_t short_size = raidz_short_size(rm);
 
+	panic("not ABD ready");
+
 	raidz_math_begin();
 
 	/* short_size */
@@ -141,6 +144,8 @@ raidz_generate_pq_impl(raidz_map_t * const rm)
 	const size_t psize = raidz_big_size(rm);
 	const size_t short_size = raidz_short_size(rm);
 
+	panic("not ABD ready");
+
 	raidz_math_begin();
 
 	/* short_size */
@@ -208,6 +213,8 @@ raidz_generate_pqr_impl(raidz_map_t * const rm)
 	const size_t psize = raidz_big_size(rm);
 	const size_t short_size = raidz_short_size(rm);
 
+	panic("not ABD ready");
+
 	raidz_math_begin();
 
 	/* short_size */
diff --git a/module/zfs/vdev_raidz_math_scalar.c b/module/zfs/vdev_raidz_math_scalar.c
index 993d406e6..1d782b633 100644
--- a/module/zfs/vdev_raidz_math_scalar.c
+++ b/module/zfs/vdev_raidz_math_scalar.c
@@ -24,7 +24,6 @@
  */
 
 #include <sys/vdev_raidz_impl.h>
-
 /*
  * Provide native CPU scalar routines.
  * Support 32bit and 64bit CPUs.
diff --git a/module/zfs/vdev_raidz_math_ssse3.c b/module/zfs/vdev_raidz_math_ssse3.c
index d93441349..81f1b9a07 100644
--- a/module/zfs/vdev_raidz_math_ssse3.c
+++ b/module/zfs/vdev_raidz_math_ssse3.c
@@ -403,8 +403,13 @@ DEFINE_REC_METHODS(ssse3);
 static boolean_t
 raidz_will_ssse3_work(void)
 {
+/* ABD Bringup -- vector code not ready */
+#if 1
+	return (B_FALSE);
+#else
 	return (zfs_sse_available() && zfs_sse2_available() &&
 	    zfs_ssse3_available());
+#endif
 }
 
 const raidz_impl_ops_t vdev_raidz_ssse3_impl = {
diff --git a/module/zfs/zil.c b/module/zfs/zil.c
index 760f0a891..b2d07166e 100644
--- a/module/zfs/zil.c
+++ b/module/zfs/zil.c
@@ -40,6 +40,7 @@
 #include <sys/dsl_pool.h>
 #include <sys/metaslab.h>
 #include <sys/trace_zil.h>
+#include <sys/abd.h>
 
 /*
  * The zfs intent log (ZIL) saves transaction records of system calls
@@ -878,6 +879,7 @@ zil_lwb_write_done(zio_t *zio)
 	 * one in zil_commit_writer(). zil_sync() will only remove
 	 * the lwb if lwb_buf is null.
 	 */
+	abd_put(zio->io_abd);
 	zio_buf_free(lwb->lwb_buf, lwb->lwb_sz);
 	mutex_enter(&zilog->zl_lock);
 	lwb->lwb_zio = NULL;
@@ -914,12 +916,14 @@ zil_lwb_write_init(zilog_t *zilog, lwb_t *lwb)
 	/* Lock so zil_sync() doesn't fastwrite_unmark after zio is created */
 	mutex_enter(&zilog->zl_lock);
 	if (lwb->lwb_zio == NULL) {
+		abd_t *lwb_abd = abd_get_from_buf(lwb->lwb_buf,
+		    BP_GET_LSIZE(&lwb->lwb_blk));
 		if (!lwb->lwb_fastwrite) {
 			metaslab_fastwrite_mark(zilog->zl_spa, &lwb->lwb_blk);
 			lwb->lwb_fastwrite = 1;
 		}
 		lwb->lwb_zio = zio_rewrite(zilog->zl_root_zio, zilog->zl_spa,
-		    0, &lwb->lwb_blk, lwb->lwb_buf, BP_GET_LSIZE(&lwb->lwb_blk),
+		    0, &lwb->lwb_blk, lwb_abd, BP_GET_LSIZE(&lwb->lwb_blk),
 		    zil_lwb_write_done, lwb, ZIO_PRIORITY_SYNC_WRITE,
 		    ZIO_FLAG_CANFAIL | ZIO_FLAG_DONT_PROPAGATE |
 		    ZIO_FLAG_FASTWRITE, &zb);
diff --git a/module/zfs/zio.c b/module/zfs/zio.c
index 223c20abe..b608ed6ea 100644
--- a/module/zfs/zio.c
+++ b/module/zfs/zio.c
@@ -42,6 +42,7 @@
 #include <sys/metaslab_impl.h>
 #include <sys/time.h>
 #include <sys/trace_zio.h>
+#include <sys/abd.h>
 
 /*
  * ==========================================================================
@@ -67,6 +68,11 @@ kmem_cache_t *zio_cache;
 kmem_cache_t *zio_link_cache;
 kmem_cache_t *zio_buf_cache[SPA_MAXBLOCKSIZE >> SPA_MINBLOCKSHIFT];
 kmem_cache_t *zio_data_buf_cache[SPA_MAXBLOCKSIZE >> SPA_MINBLOCKSHIFT];
+#if defined(ZFS_DEBUG) && !defined(_KERNEL)
+uint64_t zio_buf_cache_allocs[SPA_MAXBLOCKSIZE >> SPA_MINBLOCKSHIFT];
+uint64_t zio_buf_cache_frees[SPA_MAXBLOCKSIZE >> SPA_MINBLOCKSHIFT];
+#endif
+
 int zio_delay_max = ZIO_DELAY_MAX;
 
 #define	ZIO_PIPELINE_CONTINUE		0x100
@@ -212,6 +218,13 @@ zio_fini(void)
 		if (((c + 1) << SPA_MINBLOCKSHIFT) > zfs_max_recordsize)
 			break;
 #endif
+#if defined(ZFS_DEBUG) && !defined(_KERNEL)
+		if (zio_buf_cache_allocs[c] != zio_buf_cache_frees[c])
+			(void) printf("zio_fini: [%d] %llu != %llu\n",
+			    (int)((c + 1) << SPA_MINBLOCKSHIFT),
+			    (long long unsigned)zio_buf_cache_allocs[c],
+			    (long long unsigned)zio_buf_cache_frees[c]);
+#endif
 		if (zio_buf_cache[c] != last_cache) {
 			last_cache = zio_buf_cache[c];
 			kmem_cache_destroy(zio_buf_cache[c]);
@@ -251,6 +264,9 @@ zio_buf_alloc(size_t size)
 	size_t c = (size - 1) >> SPA_MINBLOCKSHIFT;
 
 	VERIFY3U(c, <, SPA_MAXBLOCKSIZE >> SPA_MINBLOCKSHIFT);
+#if defined(ZFS_DEBUG) && !defined(_KERNEL)
+	atomic_add_64(&zio_buf_cache_allocs[c], 1);
+#endif
 
 	return (kmem_cache_alloc(zio_buf_cache[c], KM_PUSHPAGE));
 }
@@ -271,26 +287,15 @@ zio_data_buf_alloc(size_t size)
 	return (kmem_cache_alloc(zio_data_buf_cache[c], KM_PUSHPAGE));
 }
 
-/*
- * Use zio_buf_alloc_flags when specific allocation flags are needed.  e.g.
- * passing KM_NOSLEEP when it is acceptable for an allocation to fail.
- */
-void *
-zio_buf_alloc_flags(size_t size, int flags)
-{
-	size_t c = (size - 1) >> SPA_MINBLOCKSHIFT;
-
-	VERIFY3U(c, <, SPA_MAXBLOCKSIZE >> SPA_MINBLOCKSHIFT);
-
-	return (kmem_cache_alloc(zio_buf_cache[c], flags));
-}
-
 void
 zio_buf_free(void *buf, size_t size)
 {
 	size_t c = (size - 1) >> SPA_MINBLOCKSHIFT;
 
 	VERIFY3U(c, <, SPA_MAXBLOCKSIZE >> SPA_MINBLOCKSHIFT);
+#if defined(ZFS_DEBUG) && !defined(_KERNEL)
+	atomic_add_64(&zio_buf_cache_frees[c], 1);
+#endif
 
 	kmem_cache_free(zio_buf_cache[c], buf);
 }
@@ -311,12 +316,18 @@ zio_data_buf_free(void *buf, size_t size)
  * ==========================================================================
  */
 void
-zio_push_transform(zio_t *zio, void *data, uint64_t size, uint64_t bufsize,
+zio_push_transform(zio_t *zio, abd_t *data, uint64_t size, uint64_t bufsize,
 	zio_transform_func_t *transform)
 {
 	zio_transform_t *zt = kmem_alloc(sizeof (zio_transform_t), KM_SLEEP);
 
-	zt->zt_orig_data = zio->io_data;
+	/*
+	 * Ensure that anyone expecting this zio to contain a linear ABD isn't
+	 * going to get a nasty surprise when they try to access the data.
+	 */
+	IMPLY(abd_is_linear(zio->io_abd), abd_is_linear(data));
+
+	zt->zt_orig_abd = zio->io_abd;
 	zt->zt_orig_size = zio->io_size;
 	zt->zt_bufsize = bufsize;
 	zt->zt_transform = transform;
@@ -324,7 +335,7 @@ zio_push_transform(zio_t *zio, void *data, uint64_t size, uint64_t bufsize,
 	zt->zt_next = zio->io_transform_stack;
 	zio->io_transform_stack = zt;
 
-	zio->io_data = data;
+	zio->io_abd = data;
 	zio->io_size = size;
 }
 
@@ -336,12 +347,12 @@ zio_pop_transforms(zio_t *zio)
 	while ((zt = zio->io_transform_stack) != NULL) {
 		if (zt->zt_transform != NULL)
 			zt->zt_transform(zio,
-			    zt->zt_orig_data, zt->zt_orig_size);
+			    zt->zt_orig_abd, zt->zt_orig_size);
 
 		if (zt->zt_bufsize != 0)
-			zio_buf_free(zio->io_data, zt->zt_bufsize);
+			abd_free(zio->io_abd);
 
-		zio->io_data = zt->zt_orig_data;
+		zio->io_abd = zt->zt_orig_abd;
 		zio->io_size = zt->zt_orig_size;
 		zio->io_transform_stack = zt->zt_next;
 
@@ -355,21 +366,26 @@ zio_pop_transforms(zio_t *zio)
  * ==========================================================================
  */
 static void
-zio_subblock(zio_t *zio, void *data, uint64_t size)
+zio_subblock(zio_t *zio, abd_t *data, uint64_t size)
 {
 	ASSERT(zio->io_size > size);
 
 	if (zio->io_type == ZIO_TYPE_READ)
-		bcopy(zio->io_data, data, size);
+		abd_copy(data, zio->io_abd, size);
 }
 
 static void
-zio_decompress(zio_t *zio, void *data, uint64_t size)
+zio_decompress(zio_t *zio, abd_t *data, uint64_t size)
 {
-	if (zio->io_error == 0 &&
-	    zio_decompress_data(BP_GET_COMPRESS(zio->io_bp),
-	    zio->io_data, data, zio->io_size, size) != 0)
-		zio->io_error = SET_ERROR(EIO);
+	if (zio->io_error == 0) {
+		void *tmp = abd_borrow_buf(data, size);
+		int ret = zio_decompress_data(BP_GET_COMPRESS(zio->io_bp),
+		    zio->io_abd, tmp, zio->io_size, size);
+		abd_return_buf_copy(data, tmp, size);
+
+		if (ret != 0)
+			zio->io_error = SET_ERROR(EIO);
+	}
 }
 
 /*
@@ -552,7 +568,7 @@ zio_timestamp_compare(const void *x1, const void *x2)
  */
 static zio_t *
 zio_create(zio_t *pio, spa_t *spa, uint64_t txg, const blkptr_t *bp,
-    void *data, uint64_t lsize, uint64_t psize, zio_done_func_t *done,
+    abd_t *data, uint64_t lsize, uint64_t psize, zio_done_func_t *done,
     void *private, zio_type_t type, zio_priority_t priority,
     enum zio_flag flags, vdev_t *vd, uint64_t offset,
     const zbookmark_phys_t *zb, enum zio_stage stage,
@@ -611,7 +627,7 @@ zio_create(zio_t *pio, spa_t *spa, uint64_t txg, const blkptr_t *bp,
 	zio->io_priority = priority;
 	zio->io_vd = vd;
 	zio->io_offset = offset;
-	zio->io_orig_data = zio->io_data = data;
+	zio->io_orig_abd = zio->io_abd = data;
 	zio->io_orig_size = zio->io_size = psize;
 	zio->io_lsize = lsize;
 	zio->io_orig_flags = zio->io_flags = flags;
@@ -755,7 +771,7 @@ zfs_blkptr_verify(spa_t *spa, const blkptr_t *bp)
 
 zio_t *
 zio_read(zio_t *pio, spa_t *spa, const blkptr_t *bp,
-    void *data, uint64_t size, zio_done_func_t *done, void *private,
+    abd_t *data, uint64_t size, zio_done_func_t *done, void *private,
     zio_priority_t priority, enum zio_flag flags, const zbookmark_phys_t *zb)
 {
 	zio_t *zio;
@@ -773,7 +789,7 @@ zio_read(zio_t *pio, spa_t *spa, const blkptr_t *bp,
 
 zio_t *
 zio_write(zio_t *pio, spa_t *spa, uint64_t txg, blkptr_t *bp,
-    void *data, uint64_t lsize, uint64_t psize, const zio_prop_t *zp,
+    abd_t *data, uint64_t lsize, uint64_t psize, const zio_prop_t *zp,
     zio_done_func_t *ready, zio_done_func_t *children_ready,
     zio_done_func_t *physdone, zio_done_func_t *done,
     void *private, zio_priority_t priority, enum zio_flag flags,
@@ -814,7 +830,7 @@ zio_write(zio_t *pio, spa_t *spa, uint64_t txg, blkptr_t *bp,
 }
 
 zio_t *
-zio_rewrite(zio_t *pio, spa_t *spa, uint64_t txg, blkptr_t *bp, void *data,
+zio_rewrite(zio_t *pio, spa_t *spa, uint64_t txg, blkptr_t *bp, abd_t *data,
     uint64_t size, zio_done_func_t *done, void *private,
     zio_priority_t priority, enum zio_flag flags, zbookmark_phys_t *zb)
 {
@@ -967,7 +983,7 @@ zio_ioctl(zio_t *pio, spa_t *spa, vdev_t *vd, int cmd,
 
 zio_t *
 zio_read_phys(zio_t *pio, vdev_t *vd, uint64_t offset, uint64_t size,
-    void *data, int checksum, zio_done_func_t *done, void *private,
+    abd_t *data, int checksum, zio_done_func_t *done, void *private,
     zio_priority_t priority, enum zio_flag flags, boolean_t labels)
 {
 	zio_t *zio;
@@ -988,7 +1004,7 @@ zio_read_phys(zio_t *pio, vdev_t *vd, uint64_t offset, uint64_t size,
 
 zio_t *
 zio_write_phys(zio_t *pio, vdev_t *vd, uint64_t offset, uint64_t size,
-    void *data, int checksum, zio_done_func_t *done, void *private,
+    abd_t *data, int checksum, zio_done_func_t *done, void *private,
     zio_priority_t priority, enum zio_flag flags, boolean_t labels)
 {
 	zio_t *zio;
@@ -1011,8 +1027,9 @@ zio_write_phys(zio_t *pio, vdev_t *vd, uint64_t offset, uint64_t size,
 		 * Therefore, we must make a local copy in case the data is
 		 * being written to multiple places in parallel.
 		 */
-		void *wbuf = zio_buf_alloc(size);
-		bcopy(data, wbuf, size);
+		abd_t *wbuf = abd_alloc_sametype(data, size);
+		abd_copy(wbuf, data, size);
+
 		zio_push_transform(zio, wbuf, size, size, NULL);
 	}
 
@@ -1024,7 +1041,7 @@ zio_write_phys(zio_t *pio, vdev_t *vd, uint64_t offset, uint64_t size,
  */
 zio_t *
 zio_vdev_child_io(zio_t *pio, blkptr_t *bp, vdev_t *vd, uint64_t offset,
-	void *data, uint64_t size, int type, zio_priority_t priority,
+	abd_t *data, uint64_t size, int type, zio_priority_t priority,
 	enum zio_flag flags, zio_done_func_t *done, void *private)
 {
 	enum zio_stage pipeline = ZIO_VDEV_CHILD_PIPELINE;
@@ -1090,7 +1107,7 @@ zio_vdev_child_io(zio_t *pio, blkptr_t *bp, vdev_t *vd, uint64_t offset,
 }
 
 zio_t *
-zio_vdev_delegated_io(vdev_t *vd, uint64_t offset, void *data, uint64_t size,
+zio_vdev_delegated_io(vdev_t *vd, uint64_t offset, abd_t *data, uint64_t size,
 	int type, zio_priority_t priority, enum zio_flag flags,
 	zio_done_func_t *done, void *private)
 {
@@ -1151,14 +1168,17 @@ zio_read_bp_init(zio_t *zio)
 	    !(zio->io_flags & ZIO_FLAG_RAW)) {
 		uint64_t psize =
 		    BP_IS_EMBEDDED(bp) ? BPE_GET_PSIZE(bp) : BP_GET_PSIZE(bp);
-		void *cbuf = zio_buf_alloc(psize);
-
-		zio_push_transform(zio, cbuf, psize, psize, zio_decompress);
+		zio_push_transform(zio, abd_alloc_sametype(zio->io_abd, psize),
+		    psize, psize, zio_decompress);
 	}
 
 	if (BP_IS_EMBEDDED(bp) && BPE_GET_ETYPE(bp) == BP_EMBEDDED_TYPE_DATA) {
+		int psize = BPE_GET_PSIZE(bp);
+		void *data = abd_borrow_buf(zio->io_abd, psize);
+
 		zio->io_pipeline = ZIO_INTERLOCK_PIPELINE;
-		decode_embedded_bp_compressed(bp, zio->io_data);
+		decode_embedded_bp_compressed(bp, data);
+		abd_return_buf_copy(zio->io_abd, data, psize);
 	} else {
 		ASSERT(!BP_IS_EMBEDDED(bp));
 	}
@@ -1299,7 +1319,7 @@ zio_write_compress(zio_t *zio)
 	/* If it's a compressed write that is not raw, compress the buffer. */
 	if (compress != ZIO_COMPRESS_OFF && psize == lsize) {
 		void *cbuf = zio_buf_alloc(lsize);
-		psize = zio_compress_data(compress, zio->io_data, cbuf, lsize);
+		psize = zio_compress_data(compress, zio->io_abd, cbuf, lsize);
 		if (psize == 0 || psize == lsize) {
 			compress = ZIO_COMPRESS_OFF;
 			zio_buf_free(cbuf, lsize);
@@ -1337,9 +1357,11 @@ zio_write_compress(zio_t *zio)
 				zio_buf_free(cbuf, lsize);
 				psize = lsize;
 			} else {
-				bzero((char *)cbuf + psize, rounded - psize);
+				abd_t *cdata = abd_get_from_buf(cbuf, lsize);
+				abd_take_ownership_of_buf(cdata, B_TRUE);
+				abd_zero_off(cdata, psize, rounded - psize);
 				psize = rounded;
-				zio_push_transform(zio, cbuf,
+				zio_push_transform(zio, cdata,
 				    psize, lsize, NULL);
 			}
 		}
@@ -1942,26 +1964,38 @@ zio_resume_wait(spa_t *spa)
  * ==========================================================================
  */
 
+static void
+zio_gang_issue_func_done(zio_t *zio)
+{
+	abd_put(zio->io_abd);
+}
+
 static zio_t *
-zio_read_gang(zio_t *pio, blkptr_t *bp, zio_gang_node_t *gn, void *data)
+zio_read_gang(zio_t *pio, blkptr_t *bp, zio_gang_node_t *gn, abd_t *data,
+    uint64_t offset)
 {
 	if (gn != NULL)
 		return (pio);
 
-	return (zio_read(pio, pio->io_spa, bp, data, BP_GET_PSIZE(bp),
-	    NULL, NULL, pio->io_priority, ZIO_GANG_CHILD_FLAGS(pio),
+	return (zio_read(pio, pio->io_spa, bp, abd_get_offset(data, offset),
+	    BP_GET_PSIZE(bp), zio_gang_issue_func_done,
+	    NULL, pio->io_priority, ZIO_GANG_CHILD_FLAGS(pio),
 	    &pio->io_bookmark));
 }
 
-zio_t *
-zio_rewrite_gang(zio_t *pio, blkptr_t *bp, zio_gang_node_t *gn, void *data)
+static zio_t *
+zio_rewrite_gang(zio_t *pio, blkptr_t *bp, zio_gang_node_t *gn, abd_t *data,
+    uint64_t offset)
 {
 	zio_t *zio;
 
 	if (gn != NULL) {
+		abd_t *gbh_abd =
+		    abd_get_from_buf(gn->gn_gbh, SPA_GANGBLOCKSIZE);
 		zio = zio_rewrite(pio, pio->io_spa, pio->io_txg, bp,
-		    gn->gn_gbh, SPA_GANGBLOCKSIZE, NULL, NULL, pio->io_priority,
-		    ZIO_GANG_CHILD_FLAGS(pio), &pio->io_bookmark);
+		    gbh_abd, SPA_GANGBLOCKSIZE, zio_gang_issue_func_done, NULL,
+		    pio->io_priority, ZIO_GANG_CHILD_FLAGS(pio),
+		    &pio->io_bookmark);
 		/*
 		 * As we rewrite each gang header, the pipeline will compute
 		 * a new gang block header checksum for it; but no one will
@@ -1972,8 +2006,12 @@ zio_rewrite_gang(zio_t *pio, blkptr_t *bp, zio_gang_node_t *gn, void *data)
 		 * this is just good hygiene.)
 		 */
 		if (gn != pio->io_gang_leader->io_gang_tree) {
+			abd_t *buf = abd_get_offset(data, offset);
+
 			zio_checksum_compute(zio, BP_GET_CHECKSUM(bp),
-			    data, BP_GET_PSIZE(bp));
+			    buf, BP_GET_PSIZE(bp));
+
+			abd_put(buf);
 		}
 		/*
 		 * If we are here to damage data for testing purposes,
@@ -1983,7 +2021,8 @@ zio_rewrite_gang(zio_t *pio, blkptr_t *bp, zio_gang_node_t *gn, void *data)
 			zio->io_pipeline &= ~ZIO_VDEV_IO_STAGES;
 	} else {
 		zio = zio_rewrite(pio, pio->io_spa, pio->io_txg, bp,
-		    data, BP_GET_PSIZE(bp), NULL, NULL, pio->io_priority,
+		    abd_get_offset(data, offset), BP_GET_PSIZE(bp),
+		    zio_gang_issue_func_done, NULL, pio->io_priority,
 		    ZIO_GANG_CHILD_FLAGS(pio), &pio->io_bookmark);
 	}
 
@@ -1991,16 +2030,18 @@ zio_rewrite_gang(zio_t *pio, blkptr_t *bp, zio_gang_node_t *gn, void *data)
 }
 
 /* ARGSUSED */
-zio_t *
-zio_free_gang(zio_t *pio, blkptr_t *bp, zio_gang_node_t *gn, void *data)
+static zio_t *
+zio_free_gang(zio_t *pio, blkptr_t *bp, zio_gang_node_t *gn, abd_t *data,
+    uint64_t offset)
 {
 	return (zio_free_sync(pio, pio->io_spa, pio->io_txg, bp,
 	    ZIO_GANG_CHILD_FLAGS(pio)));
 }
 
 /* ARGSUSED */
-zio_t *
-zio_claim_gang(zio_t *pio, blkptr_t *bp, zio_gang_node_t *gn, void *data)
+static zio_t *
+zio_claim_gang(zio_t *pio, blkptr_t *bp, zio_gang_node_t *gn, abd_t *data,
+    uint64_t offset)
 {
 	return (zio_claim(pio, pio->io_spa, pio->io_txg, bp,
 	    NULL, NULL, ZIO_GANG_CHILD_FLAGS(pio)));
@@ -2064,13 +2105,14 @@ static void
 zio_gang_tree_assemble(zio_t *gio, blkptr_t *bp, zio_gang_node_t **gnpp)
 {
 	zio_gang_node_t *gn = zio_gang_node_alloc(gnpp);
+	abd_t *gbh_abd = abd_get_from_buf(gn->gn_gbh, SPA_GANGBLOCKSIZE);
 
 	ASSERT(gio->io_gang_leader == gio);
 	ASSERT(BP_IS_GANG(bp));
 
-	zio_nowait(zio_read(gio, gio->io_spa, bp, gn->gn_gbh,
-	    SPA_GANGBLOCKSIZE, zio_gang_tree_assemble_done, gn,
-	    gio->io_priority, ZIO_GANG_CHILD_FLAGS(gio), &gio->io_bookmark));
+	zio_nowait(zio_read(gio, gio->io_spa, bp, gbh_abd, SPA_GANGBLOCKSIZE,
+	    zio_gang_tree_assemble_done, gn, gio->io_priority,
+	    ZIO_GANG_CHILD_FLAGS(gio), &gio->io_bookmark));
 }
 
 static void
@@ -2087,13 +2129,16 @@ zio_gang_tree_assemble_done(zio_t *zio)
 	if (zio->io_error)
 		return;
 
+	/* this ABD was created from a linear buf in zio_gang_tree_assemble */
 	if (BP_SHOULD_BYTESWAP(bp))
-		byteswap_uint64_array(zio->io_data, zio->io_size);
+		byteswap_uint64_array(abd_to_buf(zio->io_abd), zio->io_size);
 
-	ASSERT(zio->io_data == gn->gn_gbh);
+	ASSERT3P(abd_to_buf(zio->io_abd), ==, gn->gn_gbh);
 	ASSERT(zio->io_size == SPA_GANGBLOCKSIZE);
 	ASSERT(gn->gn_gbh->zg_tail.zec_magic == ZEC_MAGIC);
 
+	abd_put(zio->io_abd);
+
 	for (g = 0; g < SPA_GBH_NBLKPTRS; g++) {
 		blkptr_t *gbp = &gn->gn_gbh->zg_blkptr[g];
 		if (!BP_IS_GANG(gbp))
@@ -2103,7 +2148,8 @@ zio_gang_tree_assemble_done(zio_t *zio)
 }
 
 static void
-zio_gang_tree_issue(zio_t *pio, zio_gang_node_t *gn, blkptr_t *bp, void *data)
+zio_gang_tree_issue(zio_t *pio, zio_gang_node_t *gn, blkptr_t *bp, abd_t *data,
+    uint64_t offset)
 {
 	zio_t *gio = pio->io_gang_leader;
 	zio_t *zio;
@@ -2117,7 +2163,7 @@ zio_gang_tree_issue(zio_t *pio, zio_gang_node_t *gn, blkptr_t *bp, void *data)
 	 * If you're a gang header, your data is in gn->gn_gbh.
 	 * If you're a gang member, your data is in 'data' and gn == NULL.
 	 */
-	zio = zio_gang_issue_func[gio->io_type](pio, bp, gn, data);
+	zio = zio_gang_issue_func[gio->io_type](pio, bp, gn, data, offset);
 
 	if (gn != NULL) {
 		ASSERT(gn->gn_gbh->zg_tail.zec_magic == ZEC_MAGIC);
@@ -2126,13 +2172,14 @@ zio_gang_tree_issue(zio_t *pio, zio_gang_node_t *gn, blkptr_t *bp, void *data)
 			blkptr_t *gbp = &gn->gn_gbh->zg_blkptr[g];
 			if (BP_IS_HOLE(gbp))
 				continue;
-			zio_gang_tree_issue(zio, gn->gn_child[g], gbp, data);
-			data = (char *)data + BP_GET_PSIZE(gbp);
+			zio_gang_tree_issue(zio, gn->gn_child[g], gbp, data,
+			    offset);
+			offset += BP_GET_PSIZE(gbp);
 		}
 	}
 
 	if (gn == gio->io_gang_tree)
-		ASSERT3P((char *)gio->io_data + gio->io_size, ==, data);
+		ASSERT3U(gio->io_size, ==, offset);
 
 	if (zio != pio)
 		zio_nowait(zio);
@@ -2165,7 +2212,8 @@ zio_gang_issue(zio_t *zio)
 	ASSERT(zio->io_child_type > ZIO_CHILD_GANG);
 
 	if (zio->io_child_error[ZIO_CHILD_GANG] == 0)
-		zio_gang_tree_issue(zio, zio->io_gang_tree, bp, zio->io_data);
+		zio_gang_tree_issue(zio, zio->io_gang_tree, bp, zio->io_abd,
+		    0);
 	else
 		zio_gang_tree_free(&zio->io_gang_tree);
 
@@ -2205,6 +2253,12 @@ zio_write_gang_member_ready(zio_t *zio)
 	mutex_exit(&pio->io_lock);
 }
 
+static void
+zio_write_gang_done(zio_t *zio)
+{
+	abd_put(zio->io_abd);
+}
+
 static int
 zio_write_gang_block(zio_t *pio)
 {
@@ -2215,6 +2269,7 @@ zio_write_gang_block(zio_t *pio)
 	zio_t *zio;
 	zio_gang_node_t *gn, **gnpp;
 	zio_gbh_phys_t *gbh;
+	abd_t *gbh_abd;
 	uint64_t txg = pio->io_txg;
 	uint64_t resid = pio->io_size;
 	uint64_t lsize;
@@ -2275,12 +2330,14 @@ zio_write_gang_block(zio_t *pio)
 	gn = zio_gang_node_alloc(gnpp);
 	gbh = gn->gn_gbh;
 	bzero(gbh, SPA_GANGBLOCKSIZE);
+	gbh_abd = abd_get_from_buf(gbh, SPA_GANGBLOCKSIZE);
 
 	/*
 	 * Create the gang header.
 	 */
-	zio = zio_rewrite(pio, spa, txg, bp, gbh, SPA_GANGBLOCKSIZE, NULL, NULL,
-	    pio->io_priority, ZIO_GANG_CHILD_FLAGS(pio), &pio->io_bookmark);
+	zio = zio_rewrite(pio, spa, txg, bp, gbh_abd, SPA_GANGBLOCKSIZE,
+	    zio_write_gang_done, NULL, pio->io_priority,
+	    ZIO_GANG_CHILD_FLAGS(pio), &pio->io_bookmark);
 
 	/*
 	 * Create and nowait the gang children.
@@ -2302,9 +2359,9 @@ zio_write_gang_block(zio_t *pio)
 		zp.zp_nopwrite = B_FALSE;
 
 		cio = zio_write(zio, spa, txg, &gbh->zg_blkptr[g],
-		    (char *)pio->io_data + (pio->io_size - resid), lsize,
-		    lsize, &zp, zio_write_gang_member_ready, NULL, NULL, NULL,
-		    &gn->gn_child[g], pio->io_priority,
+		    abd_get_offset(pio->io_abd, pio->io_size - resid), lsize,
+		    lsize, &zp, zio_write_gang_member_ready, NULL, NULL,
+		    zio_write_gang_done, &gn->gn_child[g], pio->io_priority,
 		    ZIO_GANG_CHILD_FLAGS(pio), &pio->io_bookmark);
 
 		if (pio->io_flags & ZIO_FLAG_IO_ALLOCATING) {
@@ -2320,7 +2377,6 @@ zio_write_gang_block(zio_t *pio)
 			    zp.zp_copies, cio, flags));
 		}
 		zio_nowait(cio);
-
 	}
 
 	/*
@@ -2423,10 +2479,11 @@ zio_ddt_child_read_done(zio_t *zio)
 	ddp = ddt_phys_select(dde, bp);
 	if (zio->io_error == 0)
 		ddt_phys_clear(ddp);	/* this ddp doesn't need repair */
-	if (zio->io_error == 0 && dde->dde_repair_data == NULL)
-		dde->dde_repair_data = zio->io_data;
+
+	if (zio->io_error == 0 && dde->dde_repair_abd == NULL)
+		dde->dde_repair_abd = zio->io_abd;
 	else
-		zio_buf_free(zio->io_data, zio->io_size);
+		abd_free(zio->io_abd);
 	mutex_exit(&pio->io_lock);
 }
 
@@ -2459,16 +2516,16 @@ zio_ddt_read_start(zio_t *zio)
 			ddt_bp_create(ddt->ddt_checksum, &dde->dde_key, ddp,
 			    &blk);
 			zio_nowait(zio_read(zio, zio->io_spa, &blk,
-			    zio_buf_alloc(zio->io_size), zio->io_size,
-			    zio_ddt_child_read_done, dde, zio->io_priority,
-			    ZIO_DDT_CHILD_FLAGS(zio) | ZIO_FLAG_DONT_PROPAGATE,
-			    &zio->io_bookmark));
+			    abd_alloc_for_io(zio->io_size, B_TRUE),
+			    zio->io_size, zio_ddt_child_read_done, dde,
+			    zio->io_priority, ZIO_DDT_CHILD_FLAGS(zio) |
+			    ZIO_FLAG_DONT_PROPAGATE, &zio->io_bookmark));
 		}
 		return (ZIO_PIPELINE_CONTINUE);
 	}
 
 	zio_nowait(zio_read(zio, zio->io_spa, bp,
-	    zio->io_data, zio->io_size, NULL, NULL, zio->io_priority,
+	    zio->io_abd, zio->io_size, NULL, NULL, zio->io_priority,
 	    ZIO_DDT_CHILD_FLAGS(zio), &zio->io_bookmark));
 
 	return (ZIO_PIPELINE_CONTINUE);
@@ -2498,8 +2555,9 @@ zio_ddt_read_done(zio_t *zio)
 			zio_taskq_dispatch(zio, ZIO_TASKQ_ISSUE, B_FALSE);
 			return (ZIO_PIPELINE_STOP);
 		}
-		if (dde->dde_repair_data != NULL) {
-			bcopy(dde->dde_repair_data, zio->io_data, zio->io_size);
+		if (dde->dde_repair_abd != NULL) {
+			abd_copy(zio->io_abd, dde->dde_repair_abd,
+			    zio->io_size);
 			zio->io_child_error[ZIO_CHILD_DDT] = 0;
 		}
 		ddt_repair_done(ddt, dde);
@@ -2537,12 +2595,10 @@ zio_ddt_collision(zio_t *zio, ddt_t *ddt, ddt_entry_t *dde)
 
 		if (lio != NULL && do_raw) {
 			return (lio->io_size != zio->io_size ||
-			    bcmp(zio->io_data, lio->io_data,
-			    zio->io_size) != 0);
+			    abd_cmp(zio->io_abd, lio->io_abd) != 0);
 		} else if (lio != NULL) {
 			return (lio->io_orig_size != zio->io_orig_size ||
-			    bcmp(zio->io_orig_data, lio->io_orig_data,
-			    zio->io_orig_size) != 0);
+			    abd_cmp(zio->io_orig_abd, lio->io_orig_abd) != 0);
 		}
 	}
 
@@ -2552,7 +2608,7 @@ zio_ddt_collision(zio_t *zio, ddt_t *ddt, ddt_entry_t *dde)
 		if (ddp->ddp_phys_birth != 0 && do_raw) {
 			blkptr_t blk = *zio->io_bp;
 			uint64_t psize;
-			void *tmpbuf;
+			abd_t *tmpabd;
 			int error;
 
 			ddt_bp_fill(ddp, &blk, ddp->ddp_phys_birth);
@@ -2563,19 +2619,19 @@ zio_ddt_collision(zio_t *zio, ddt_t *ddt, ddt_entry_t *dde)
 
 			ddt_exit(ddt);
 
-			tmpbuf = zio_buf_alloc(psize);
+			tmpabd = abd_alloc_for_io(psize, B_TRUE);
 
-			error = zio_wait(zio_read(NULL, spa, &blk, tmpbuf,
+			error = zio_wait(zio_read(NULL, spa, &blk, tmpabd,
 			    psize, NULL, NULL, ZIO_PRIORITY_SYNC_READ,
 			    ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE |
 			    ZIO_FLAG_RAW, &zio->io_bookmark));
 
 			if (error == 0) {
-				if (bcmp(tmpbuf, zio->io_data, psize) != 0)
+				if (abd_cmp(tmpabd, zio->io_abd) != 0)
 					error = SET_ERROR(ENOENT);
 			}
 
-			zio_buf_free(tmpbuf, psize);
+			abd_free(tmpabd);
 			ddt_enter(ddt);
 			return (error != 0);
 		} else if (ddp->ddp_phys_birth != 0) {
@@ -2597,7 +2653,7 @@ zio_ddt_collision(zio_t *zio, ddt_t *ddt, ddt_entry_t *dde)
 			    &aflags, &zio->io_bookmark);
 
 			if (error == 0) {
-				if (bcmp(abuf->b_data, zio->io_orig_data,
+				if (abd_cmp_buf(zio->io_orig_abd, abuf->b_data,
 				    zio->io_orig_size) != 0)
 					error = SET_ERROR(ENOENT);
 				arc_buf_destroy(abuf, &abuf);
@@ -2762,12 +2818,12 @@ zio_ddt_write(zio_t *zio)
 			return (ZIO_PIPELINE_CONTINUE);
 		}
 
-		dio = zio_write(zio, spa, txg, bp, zio->io_orig_data,
+		dio = zio_write(zio, spa, txg, bp, zio->io_orig_abd,
 		    zio->io_orig_size, zio->io_orig_size, &czp, NULL, NULL,
 		    NULL, zio_ddt_ditto_write_done, dde, zio->io_priority,
 		    ZIO_DDT_CHILD_FLAGS(zio), &zio->io_bookmark);
 
-		zio_push_transform(dio, zio->io_data, zio->io_size, 0, NULL);
+		zio_push_transform(dio, zio->io_abd, zio->io_size, 0, NULL);
 		dde->dde_lead_zio[DDT_PHYS_DITTO] = dio;
 	}
 
@@ -2784,13 +2840,13 @@ zio_ddt_write(zio_t *zio)
 		ddt_phys_fill(ddp, bp);
 		ddt_phys_addref(ddp);
 	} else {
-		cio = zio_write(zio, spa, txg, bp, zio->io_orig_data,
+		cio = zio_write(zio, spa, txg, bp, zio->io_orig_abd,
 		    zio->io_orig_size, zio->io_orig_size, zp,
 		    zio_ddt_child_write_ready, NULL, NULL,
 		    zio_ddt_child_write_done, dde, zio->io_priority,
 		    ZIO_DDT_CHILD_FLAGS(zio), &zio->io_bookmark);
 
-		zio_push_transform(cio, zio->io_data, zio->io_size, 0, NULL);
+		zio_push_transform(cio, zio->io_abd, zio->io_size, 0, NULL);
 		dde->dde_lead_zio[p] = cio;
 	}
 
@@ -3130,11 +3186,11 @@ zio_vdev_io_start(zio_t *zio)
 	    P2PHASE(zio->io_size, align) != 0) {
 		/* Transform logical writes to be a full physical block size. */
 		uint64_t asize = P2ROUNDUP(zio->io_size, align);
-		char *abuf = zio_buf_alloc(asize);
+		abd_t *abuf = abd_alloc_sametype(zio->io_abd, asize);
 		ASSERT(vd == vd->vdev_top);
 		if (zio->io_type == ZIO_TYPE_WRITE) {
-			bcopy(zio->io_data, abuf, zio->io_size);
-			bzero(abuf + zio->io_size, asize - zio->io_size);
+			abd_copy(abuf, zio->io_abd, zio->io_size);
+			abd_zero_off(abuf, zio->io_size, asize - zio->io_size);
 		}
 		zio_push_transform(zio, abuf, asize, asize, zio_subblock);
 	}
@@ -3264,7 +3320,7 @@ zio_vsd_default_cksum_report(zio_t *zio, zio_cksum_report_t *zcr, void *ignored)
 {
 	void *buf = zio_buf_alloc(zio->io_size);
 
-	bcopy(zio->io_data, buf, zio->io_size);
+	abd_copy_to_buf(buf, zio->io_abd, zio->io_size);
 
 	zcr->zcr_cbinfo = zio->io_size;
 	zcr->zcr_cbdata = buf;
@@ -3398,7 +3454,7 @@ zio_checksum_generate(zio_t *zio)
 		}
 	}
 
-	zio_checksum_compute(zio, checksum, zio->io_data, zio->io_size);
+	zio_checksum_compute(zio, checksum, zio->io_abd, zio->io_size);
 
 	return (ZIO_PIPELINE_CONTINUE);
 }
@@ -3537,7 +3593,7 @@ zio_ready(zio_t *zio)
 		if (BP_IS_GANG(bp)) {
 			zio->io_flags &= ~ZIO_FLAG_NODATA;
 		} else {
-			ASSERT((uintptr_t)zio->io_data < SPA_MAXBLOCKSIZE);
+			ASSERT((uintptr_t)zio->io_abd < SPA_MAXBLOCKSIZE);
 			zio->io_pipeline &= ~ZIO_VDEV_IO_STAGES;
 		}
 	}
@@ -3616,6 +3672,7 @@ zio_done(zio_t *zio)
 	 * Always attempt to keep stack usage minimal here since
 	 * we can be called recurisvely up to 19 levels deep.
 	 */
+	uint64_t psize = zio->io_size;
 	zio_t *pio, *pio_next;
 	int c, w;
 	zio_link_t *zl = NULL;
@@ -3696,28 +3753,35 @@ zio_done(zio_t *zio)
 		while (zio->io_cksum_report != NULL) {
 			zio_cksum_report_t *zcr = zio->io_cksum_report;
 			uint64_t align = zcr->zcr_align;
-			uint64_t asize = P2ROUNDUP(zio->io_size, align);
-			char *abuf = zio->io_data;
-
-			if (asize != zio->io_size) {
-				abuf = zio_buf_alloc(asize);
-				bcopy(zio->io_data, abuf, zio->io_size);
-				bzero(abuf+zio->io_size, asize-zio->io_size);
+			uint64_t asize = P2ROUNDUP(psize, align);
+			char *abuf = NULL;
+			abd_t *adata = zio->io_abd;
+
+			if (asize != psize) {
+				adata = abd_alloc_linear(asize, B_TRUE);
+				abd_copy(adata, zio->io_abd, psize);
+				abd_zero_off(adata, psize, asize - psize);
 			}
 
+			if (adata != NULL)
+				abuf = abd_borrow_buf_copy(adata, asize);
+
 			zio->io_cksum_report = zcr->zcr_next;
 			zcr->zcr_next = NULL;
 			zcr->zcr_finish(zcr, abuf);
 			zfs_ereport_free_checksum(zcr);
 
-			if (asize != zio->io_size)
-				zio_buf_free(abuf, asize);
+			if (adata != NULL)
+				abd_return_buf(adata, abuf, asize);
+
+			if (asize != psize)
+				abd_free(adata);
 		}
 	}
 
 	zio_pop_transforms(zio);	/* note: may set zio->io_error */
 
-	vdev_stat_update(zio, zio->io_size);
+	vdev_stat_update(zio, psize);
 
 	/*
 	 * If this I/O is attached to a particular vdev is slow, exceeding
@@ -4098,7 +4162,6 @@ zbookmark_subtree_completed(const dnode_phys_t *dnp,
 EXPORT_SYMBOL(zio_type_name);
 EXPORT_SYMBOL(zio_buf_alloc);
 EXPORT_SYMBOL(zio_data_buf_alloc);
-EXPORT_SYMBOL(zio_buf_alloc_flags);
 EXPORT_SYMBOL(zio_buf_free);
 EXPORT_SYMBOL(zio_data_buf_free);
 
diff --git a/module/zfs/zio_checksum.c b/module/zfs/zio_checksum.c
index d3d2f05a8..37116f049 100644
--- a/module/zfs/zio_checksum.c
+++ b/module/zfs/zio_checksum.c
@@ -20,8 +20,8 @@
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2013 by Delphix. All rights reserved.
  * Copyright 2013 Saso Kiselkov. All rights reserved.
+ * Copyright (c) 2013, 2016 by Delphix. All rights reserved.
  */
 
 #include <sys/zfs_context.h>
@@ -30,6 +30,7 @@
 #include <sys/zio.h>
 #include <sys/zio_checksum.h>
 #include <sys/zil.h>
+#include <sys/abd.h>
 #include <zfs_fletcher.h>
 
 /*
@@ -92,45 +93,85 @@
 
 /*ARGSUSED*/
 static void
-zio_checksum_off(const void *buf, uint64_t size,
-    const void *ctx_template, zio_cksum_t *zcp)
+abd_checksum_off(abd_t *abd, uint64_t size,
+	const void *ctx_template, zio_cksum_t *zcp)
 {
 	ZIO_SET_CHECKSUM(zcp, 0, 0, 0, 0);
 }
 
+/*ARGSUSED*/
+void
+abd_fletcher_2_native(abd_t *abd, uint64_t size,
+    const void *ctx_template, zio_cksum_t *zcp)
+{
+	fletcher_init(zcp);
+	(void) abd_iterate_func(abd, 0, size,
+	    fletcher_2_incremental_native, zcp);
+}
+
+/*ARGSUSED*/
+void
+abd_fletcher_2_byteswap(abd_t *abd, uint64_t size,
+    const void *ctx_template, zio_cksum_t *zcp)
+{
+	fletcher_init(zcp);
+	(void) abd_iterate_func(abd, 0, size,
+	    fletcher_2_incremental_byteswap, zcp);
+}
+
+/*ARGSUSED*/
+void
+abd_fletcher_4_native(abd_t *abd, uint64_t size,
+    const void *ctx_template, zio_cksum_t *zcp)
+{
+	fletcher_init(zcp);
+	(void) abd_iterate_func(abd, 0, size,
+	    fletcher_4_incremental_native, zcp);
+}
+
+/*ARGSUSED*/
+void
+abd_fletcher_4_byteswap(abd_t *abd, uint64_t size,
+    const void *ctx_template, zio_cksum_t *zcp)
+{
+	fletcher_init(zcp);
+	(void) abd_iterate_func(abd, 0, size,
+	    fletcher_4_incremental_byteswap, zcp);
+}
+
 zio_checksum_info_t zio_checksum_table[ZIO_CHECKSUM_FUNCTIONS] = {
 	{{NULL, NULL}, NULL, NULL, 0, "inherit"},
 	{{NULL, NULL}, NULL, NULL, 0, "on"},
-	{{zio_checksum_off,		zio_checksum_off},
+	{{abd_checksum_off,		abd_checksum_off},
 	    NULL, NULL, 0, "off"},
-	{{zio_checksum_SHA256,		zio_checksum_SHA256},
+	{{abd_checksum_SHA256,		abd_checksum_SHA256},
 	    NULL, NULL, ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_EMBEDDED,
 	    "label"},
-	{{zio_checksum_SHA256,		zio_checksum_SHA256},
+	{{abd_checksum_SHA256,		abd_checksum_SHA256},
 	    NULL, NULL, ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_EMBEDDED,
 	    "gang_header"},
-	{{fletcher_2_native,		fletcher_2_byteswap},
+	{{abd_fletcher_2_native,	abd_fletcher_2_byteswap},
 	    NULL, NULL, ZCHECKSUM_FLAG_EMBEDDED, "zilog"},
-	{{fletcher_2_native,		fletcher_2_byteswap},
+	{{abd_fletcher_2_native,	abd_fletcher_2_byteswap},
 	    NULL, NULL, 0, "fletcher2"},
-	{{fletcher_4_native,		fletcher_4_byteswap},
+	{{abd_fletcher_4_native,	abd_fletcher_4_byteswap},
 	    NULL, NULL, ZCHECKSUM_FLAG_METADATA, "fletcher4"},
-	{{zio_checksum_SHA256,		zio_checksum_SHA256},
+	{{abd_checksum_SHA256,		abd_checksum_SHA256},
 	    NULL, NULL, ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_DEDUP |
 	    ZCHECKSUM_FLAG_NOPWRITE, "sha256"},
-	{{fletcher_4_native,		fletcher_4_byteswap},
+	{{abd_fletcher_4_native,	abd_fletcher_4_byteswap},
 	    NULL, NULL, ZCHECKSUM_FLAG_EMBEDDED, "zilog2"},
-	{{zio_checksum_off,		zio_checksum_off},
+	{{abd_checksum_off,		abd_checksum_off},
 	    NULL, NULL, 0, "noparity"},
-	{{zio_checksum_SHA512_native,	zio_checksum_SHA512_byteswap},
+	{{abd_checksum_SHA512_native,	abd_checksum_SHA512_byteswap},
 	    NULL, NULL, ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_DEDUP |
 	    ZCHECKSUM_FLAG_NOPWRITE, "sha512"},
-	{{zio_checksum_skein_native,	zio_checksum_skein_byteswap},
-	    zio_checksum_skein_tmpl_init, zio_checksum_skein_tmpl_free,
+	{{abd_checksum_skein_native,	abd_checksum_skein_byteswap},
+	    abd_checksum_skein_tmpl_init, abd_checksum_skein_tmpl_free,
 	    ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_DEDUP |
 	    ZCHECKSUM_FLAG_SALTED | ZCHECKSUM_FLAG_NOPWRITE, "skein"},
-	{{zio_checksum_edonr_native,	zio_checksum_edonr_byteswap},
-	    zio_checksum_edonr_tmpl_init, zio_checksum_edonr_tmpl_free,
+	{{abd_checksum_edonr_native,	abd_checksum_edonr_byteswap},
+	    abd_checksum_edonr_tmpl_init, abd_checksum_edonr_tmpl_free,
 	    ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_SALTED |
 	    ZCHECKSUM_FLAG_NOPWRITE, "edonr"},
 };
@@ -251,7 +292,7 @@ zio_checksum_template_init(enum zio_checksum checksum, spa_t *spa)
  */
 void
 zio_checksum_compute(zio_t *zio, enum zio_checksum checksum,
-	void *data, uint64_t size)
+    abd_t *abd, uint64_t size)
 {
 	blkptr_t *bp = zio->io_bp;
 	uint64_t offset = zio->io_offset;
@@ -266,6 +307,7 @@ zio_checksum_compute(zio_t *zio, enum zio_checksum checksum,
 
 	if (ci->ci_flags & ZCHECKSUM_FLAG_EMBEDDED) {
 		zio_eck_t *eck;
+		void *data = abd_to_buf(abd);
 
 		if (checksum == ZIO_CHECKSUM_ZILOG2) {
 			zil_chain_t *zilc = data;
@@ -283,18 +325,18 @@ zio_checksum_compute(zio_t *zio, enum zio_checksum checksum,
 		else
 			bp->blk_cksum = eck->zec_cksum;
 		eck->zec_magic = ZEC_MAGIC;
-		ci->ci_func[0](data, size, spa->spa_cksum_tmpls[checksum],
+		ci->ci_func[0](abd, size, spa->spa_cksum_tmpls[checksum],
 		    &cksum);
 		eck->zec_cksum = cksum;
 	} else {
-		ci->ci_func[0](data, size, spa->spa_cksum_tmpls[checksum],
+		ci->ci_func[0](abd, size, spa->spa_cksum_tmpls[checksum],
 		    &bp->blk_cksum);
 	}
 }
 
 int
 zio_checksum_error_impl(spa_t *spa, blkptr_t *bp, enum zio_checksum checksum,
-    void *data, uint64_t size, uint64_t offset, zio_bad_cksum_t *info)
+    abd_t *abd, uint64_t size, uint64_t offset, zio_bad_cksum_t *info)
 {
 	zio_checksum_info_t *ci = &zio_checksum_table[checksum];
 	int byteswap;
@@ -308,25 +350,32 @@ zio_checksum_error_impl(spa_t *spa, blkptr_t *bp, enum zio_checksum checksum,
 	if (ci->ci_flags & ZCHECKSUM_FLAG_EMBEDDED) {
 		zio_eck_t *eck;
 		zio_cksum_t verifier;
+		size_t eck_offset;
+		uint64_t data_size = size;
+		void *data = abd_borrow_buf_copy(abd, data_size);
 
 		if (checksum == ZIO_CHECKSUM_ZILOG2) {
 			zil_chain_t *zilc = data;
 			uint64_t nused;
 
 			eck = &zilc->zc_eck;
-			if (eck->zec_magic == ZEC_MAGIC)
+			if (eck->zec_magic == ZEC_MAGIC) {
 				nused = zilc->zc_nused;
-			else if (eck->zec_magic == BSWAP_64(ZEC_MAGIC))
+			} else if (eck->zec_magic == BSWAP_64(ZEC_MAGIC)) {
 				nused = BSWAP_64(zilc->zc_nused);
-			else
+			} else {
+				abd_return_buf(abd, data, data_size);
 				return (SET_ERROR(ECKSUM));
+			}
 
-			if (nused > size)
+			if (nused > data_size) {
+				abd_return_buf(abd, data, data_size);
 				return (SET_ERROR(ECKSUM));
+			}
 
 			size = P2ROUNDUP_TYPED(nused, ZIL_MIN_BLKSZ, uint64_t);
 		} else {
-			eck = (zio_eck_t *)((char *)data + size) - 1;
+			eck = (zio_eck_t *)((char *)data + data_size) - 1;
 		}
 
 		if (checksum == ZIO_CHECKSUM_GANG_HEADER)
@@ -341,11 +390,15 @@ zio_checksum_error_impl(spa_t *spa, blkptr_t *bp, enum zio_checksum checksum,
 		if (byteswap)
 			byteswap_uint64_array(&verifier, sizeof (zio_cksum_t));
 
+		eck_offset = (size_t)(&eck->zec_cksum) - (size_t)data;
 		expected_cksum = eck->zec_cksum;
 		eck->zec_cksum = verifier;
-		ci->ci_func[byteswap](data, size,
+		abd_return_buf_copy(abd, data, data_size);
+
+		ci->ci_func[byteswap](abd, size,
 		    spa->spa_cksum_tmpls[checksum], &actual_cksum);
-		eck->zec_cksum = expected_cksum;
+		abd_copy_from_buf_off(abd, &expected_cksum,
+		    eck_offset, sizeof (zio_cksum_t));
 
 		if (byteswap) {
 			byteswap_uint64_array(&expected_cksum,
@@ -354,7 +407,7 @@ zio_checksum_error_impl(spa_t *spa, blkptr_t *bp, enum zio_checksum checksum,
 	} else {
 		byteswap = BP_SHOULD_BYTESWAP(bp);
 		expected_cksum = bp->blk_cksum;
-		ci->ci_func[byteswap](data, size,
+		ci->ci_func[byteswap](abd, size,
 		    spa->spa_cksum_tmpls[checksum], &actual_cksum);
 	}
 
@@ -383,7 +436,7 @@ zio_checksum_error(zio_t *zio, zio_bad_cksum_t *info)
 	uint64_t size = (bp == NULL ? zio->io_size :
 	    (BP_IS_GANG(bp) ? SPA_GANGBLOCKSIZE : BP_GET_PSIZE(bp)));
 	uint64_t offset = zio->io_offset;
-	void *data = zio->io_data;
+	abd_t *data = zio->io_abd;
 	spa_t *spa = zio->io_spa;
 
 	error = zio_checksum_error_impl(spa, bp, checksum, data, size,
diff --git a/module/zfs/zio_compress.c b/module/zfs/zio_compress.c
index 6b8d6c39b..7e44d16e4 100644
--- a/module/zfs/zio_compress.c
+++ b/module/zfs/zio_compress.c
@@ -28,7 +28,7 @@
  */
 
 /*
- * Copyright (c) 2013 by Delphix. All rights reserved.
+ * Copyright (c) 2013, 2016 by Delphix. All rights reserved.
  */
 
 #include <sys/zfs_context.h>
@@ -41,24 +41,23 @@
 /*
  * Compression vectors.
  */
-
 zio_compress_info_t zio_compress_table[ZIO_COMPRESS_FUNCTIONS] = {
-	{NULL,			NULL,			0,	"inherit"},
-	{NULL,			NULL,			0,	"on"},
-	{NULL,			NULL,			0,	"uncompressed"},
-	{lzjb_compress,		lzjb_decompress,	0,	"lzjb"},
-	{NULL,			NULL,			0,	"empty"},
-	{gzip_compress,		gzip_decompress,	1,	"gzip-1"},
-	{gzip_compress,		gzip_decompress,	2,	"gzip-2"},
-	{gzip_compress,		gzip_decompress,	3,	"gzip-3"},
-	{gzip_compress,		gzip_decompress,	4,	"gzip-4"},
-	{gzip_compress,		gzip_decompress,	5,	"gzip-5"},
-	{gzip_compress,		gzip_decompress,	6,	"gzip-6"},
-	{gzip_compress,		gzip_decompress,	7,	"gzip-7"},
-	{gzip_compress,		gzip_decompress,	8,	"gzip-8"},
-	{gzip_compress,		gzip_decompress,	9,	"gzip-9"},
-	{zle_compress,		zle_decompress,		64,	"zle"},
-	{lz4_compress_zfs,	lz4_decompress_zfs,	0,	"lz4"},
+	{"inherit",		0,	NULL,		NULL},
+	{"on",			0,	NULL,		NULL},
+	{"uncompressed",	0,	NULL,		NULL},
+	{"lzjb",		0,	lzjb_compress,	lzjb_decompress},
+	{"empty",		0,	NULL,		NULL},
+	{"gzip-1",		1,	gzip_compress,	gzip_decompress},
+	{"gzip-2",		2,	gzip_compress,	gzip_decompress},
+	{"gzip-3",		3,	gzip_compress,	gzip_decompress},
+	{"gzip-4",		4,	gzip_compress,	gzip_decompress},
+	{"gzip-5",		5,	gzip_compress,	gzip_decompress},
+	{"gzip-6",		6,	gzip_compress,	gzip_decompress},
+	{"gzip-7",		7,	gzip_compress,	gzip_decompress},
+	{"gzip-8",		8,	gzip_compress,	gzip_decompress},
+	{"gzip-9",		9,	gzip_compress,	gzip_decompress},
+	{"zle",			64,	zle_compress,	zle_decompress},
+	{"lz4",			0,	lz4_compress_zfs, lz4_decompress_zfs}
 };
 
 enum zio_compress
@@ -85,12 +84,26 @@ zio_compress_select(spa_t *spa, enum zio_compress child,
 	return (result);
 }
 
+/*ARGSUSED*/
+static int
+zio_compress_zeroed_cb(void *data, size_t len, void *private)
+{
+	uint64_t *end = (uint64_t *)((char *)data + len);
+	uint64_t *word;
+
+	for (word = data; word < end; word++)
+		if (*word != 0)
+			return (1);
+
+	return (0);
+}
+
 size_t
-zio_compress_data(enum zio_compress c, void *src, void *dst, size_t s_len)
+zio_compress_data(enum zio_compress c, abd_t *src, void *dst, size_t s_len)
 {
-	uint64_t *word, *word_end;
 	size_t c_len, d_len;
 	zio_compress_info_t *ci = &zio_compress_table[c];
+	void *tmp;
 
 	ASSERT((uint_t)c < ZIO_COMPRESS_FUNCTIONS);
 	ASSERT((uint_t)c == ZIO_COMPRESS_EMPTY || ci->ci_compress != NULL);
@@ -99,12 +112,7 @@ zio_compress_data(enum zio_compress c, void *src, void *dst, size_t s_len)
 	 * If the data is all zeroes, we don't even need to allocate
 	 * a block for it.  We indicate this by returning zero size.
 	 */
-	word_end = (uint64_t *)((char *)src + s_len);
-	for (word = src; word < word_end; word++)
-		if (*word != 0)
-			break;
-
-	if (word == word_end)
+	if (abd_iterate_func(src, 0, s_len, zio_compress_zeroed_cb, NULL) == 0)
 		return (0);
 
 	if (c == ZIO_COMPRESS_EMPTY)
@@ -112,7 +120,11 @@ zio_compress_data(enum zio_compress c, void *src, void *dst, size_t s_len)
 
 	/* Compress at least 12.5% */
 	d_len = s_len - (s_len >> 3);
-	c_len = ci->ci_compress(src, dst, s_len, d_len, ci->ci_level);
+
+	/* No compression algorithms can read from ABDs directly */
+	tmp = abd_borrow_buf_copy(src, s_len);
+	c_len = ci->ci_compress(tmp, dst, s_len, d_len, ci->ci_level);
+	abd_return_buf(src, tmp, s_len);
 
 	if (c_len > d_len)
 		return (s_len);
@@ -122,13 +134,23 @@ zio_compress_data(enum zio_compress c, void *src, void *dst, size_t s_len)
 }
 
 int
-zio_decompress_data(enum zio_compress c, void *src, void *dst,
+zio_decompress_data_buf(enum zio_compress c, void *src, void *dst,
     size_t s_len, size_t d_len)
 {
 	zio_compress_info_t *ci = &zio_compress_table[c];
-
 	if ((uint_t)c >= ZIO_COMPRESS_FUNCTIONS || ci->ci_decompress == NULL)
 		return (SET_ERROR(EINVAL));
 
 	return (ci->ci_decompress(src, dst, s_len, d_len, ci->ci_level));
 }
+
+int
+zio_decompress_data(enum zio_compress c, abd_t *src, void *dst,
+    size_t s_len, size_t d_len)
+{
+	void *tmp = abd_borrow_buf_copy(src, s_len);
+	int ret = zio_decompress_data_buf(c, tmp, dst, s_len, d_len);
+	abd_return_buf(src, tmp, s_len);
+
+	return (ret);
+}