8021 ARC buf data scatter-ization

8100 8021 seems to cause random BAD TRAP: type=d (#gp General protection)
Reviewed by: Matthew Ahrens mahrens@delphix.com
Reviewed by: George Wilson george.wilson@delphix.com
Reviewed by: Paul Dagnelie pcd@delphix.com
Reviewed by: John Kennedy john.kennedy@delphix.com
Reviewed by: Prakash Surya prakash.surya@delphix.com
Reviewed by: Prashanth Sreenivasa pks@delphix.com
Reviewed by: Pavel Zakharov pavel.zakharov@delphix.com
Reviewed by: Chris Williamson chris.williamson@delphix.com
Approved by: Richard Lowe <richlowe@richlowe.net>

61 files changed, 2863 insertions, 819 deletions

diff --git a/usr/src/cmd/mdb/common/modules/zfs/zfs.c b/usr/src/cmd/mdb/common/modules/zfs/zfs.c
index 0658d7c639..10a2f5a4f7 100644
--- a/usr/src/cmd/mdb/common/modules/zfs/zfs.c
+++ b/usr/src/cmd/mdb/common/modules/zfs/zfs.c
@@ -3553,7 +3553,6 @@ typedef struct mdb_arc_buf_hdr_t {
 	struct {
 		uint32_t	b_bufcnt;
 		uintptr_t	b_state;
-		uintptr_t	b_pdata;
 	} b_l1hdr;
 } mdb_arc_buf_hdr_t;
 
diff --git a/usr/src/cmd/zdb/zdb.c b/usr/src/cmd/zdb/zdb.c
index 9ddf5e1021..0137e6f448 100644
--- a/usr/src/cmd/zdb/zdb.c
+++ b/usr/src/cmd/zdb/zdb.c
@@ -60,6 +60,7 @@
 #include <sys/arc.h>
 #include <sys/ddt.h>
 #include <sys/zfeature.h>
+#include <sys/abd.h>
 #include <zfs_comutil.h>
 #undef verify
 #include <libzfs.h>
@@ -2537,7 +2538,7 @@ zdb_blkptr_done(zio_t *zio)
 	zdb_cb_t *zcb = zio->io_private;
 	zbookmark_phys_t *zb = &zio->io_bookmark;
 
-	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--;
@@ -2603,7 +2604,7 @@ zdb_blkptr_cb(spa_t *spa, zilog_t *zilog, const blkptr_t *bp,
 	if (!BP_IS_EMBEDDED(bp) &&
 	    (dump_opt['c'] > 1 || (dump_opt['c'] && is_metadata))) {
 		size_t size = BP_GET_PSIZE(bp);
-		void *data = zio_data_buf_alloc(size);
+		abd_t *abd = abd_alloc(size, B_FALSE);
 		int flags = ZIO_FLAG_CANFAIL | ZIO_FLAG_SCRUB | ZIO_FLAG_RAW;
 
 		/* If it's an intent log block, failure is expected. */
@@ -2616,7 +2617,7 @@ zdb_blkptr_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(NULL, spa, bp, data, size,
+		zio_nowait(zio_read(NULL, spa, bp, abd, size,
 		    zdb_blkptr_done, zcb, ZIO_PRIORITY_ASYNC_READ, flags, zb));
 	}
 
@@ -3397,6 +3398,13 @@ name:
 	return (NULL);
 }
 
+/* ARGSUSED */
+static int
+random_get_pseudo_bytes_cb(void *buf, size_t len, void *unused)
+{
+	return (random_get_pseudo_bytes(buf, len));
+}
+
 /*
  * Read a block from a pool and print it out.  The syntax of the
  * block descriptor is:
@@ -3428,7 +3436,8 @@ zdb_read_block(char *thing, spa_t *spa)
 	uint64_t offset = 0, size = 0, psize = 0, lsize = 0, blkptr_offset = 0;
 	zio_t *zio;
 	vdev_t *vd;
-	void *pbuf, *lbuf, *buf;
+	abd_t *pabd;
+	void *lbuf, *buf;
 	char *s, *p, *dup, *vdev, *flagstr;
 	int i, error;
 
@@ -3499,7 +3508,7 @@ zdb_read_block(char *thing, spa_t *spa)
 	psize = size;
 	lsize = size;
 
-	pbuf = umem_alloc(SPA_MAXBLOCKSIZE, UMEM_NOFAIL);
+	pabd = abd_alloc_linear(SPA_MAXBLOCKSIZE, B_FALSE);
 	lbuf = umem_alloc(SPA_MAXBLOCKSIZE, UMEM_NOFAIL);
 
 	BP_ZERO(bp);
@@ -3527,15 +3536,15 @@ zdb_read_block(char *thing, spa_t *spa)
 		/*
 		 * Treat this as a normal block read.
 		 */
-		zio_nowait(zio_read(zio, spa, bp, pbuf, psize, NULL, NULL,
+		zio_nowait(zio_read(zio, spa, bp, pabd, psize, NULL, NULL,
 		    ZIO_PRIORITY_SYNC_READ,
 		    ZIO_FLAG_CANFAIL | ZIO_FLAG_RAW, NULL));
 	} else {
 		/*
 		 * Treat this as a vdev child I/O.
 		 */
-		zio_nowait(zio_vdev_child_io(zio, bp, vd, offset, pbuf, psize,
-		    ZIO_TYPE_READ, ZIO_PRIORITY_SYNC_READ,
+		zio_nowait(zio_vdev_child_io(zio, bp, vd, offset, pabd,
+		    psize, ZIO_TYPE_READ, ZIO_PRIORITY_SYNC_READ,
 		    ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_QUEUE |
 		    ZIO_FLAG_DONT_PROPAGATE | ZIO_FLAG_DONT_RETRY |
 		    ZIO_FLAG_CANFAIL | ZIO_FLAG_RAW, NULL, NULL));
@@ -3558,21 +3567,21 @@ zdb_read_block(char *thing, spa_t *spa)
 		void *pbuf2 = umem_alloc(SPA_MAXBLOCKSIZE, UMEM_NOFAIL);
 		void *lbuf2 = umem_alloc(SPA_MAXBLOCKSIZE, UMEM_NOFAIL);
 
-		bcopy(pbuf, pbuf2, psize);
+		abd_copy_to_buf(pbuf2, pabd, psize);
 
-		VERIFY(random_get_pseudo_bytes((uint8_t *)pbuf + psize,
-		    SPA_MAXBLOCKSIZE - psize) == 0);
+		VERIFY0(abd_iterate_func(pabd, psize, SPA_MAXBLOCKSIZE - psize,
+		    random_get_pseudo_bytes_cb, NULL));
 
-		VERIFY(random_get_pseudo_bytes((uint8_t *)pbuf2 + psize,
-		    SPA_MAXBLOCKSIZE - psize) == 0);
+		VERIFY0(random_get_pseudo_bytes((uint8_t *)pbuf2 + psize,
+		    SPA_MAXBLOCKSIZE - psize));
 
 		for (lsize = SPA_MAXBLOCKSIZE; lsize > psize;
 		    lsize -= SPA_MINBLOCKSIZE) {
 			for (c = 0; c < ZIO_COMPRESS_FUNCTIONS; c++) {
-				if (zio_decompress_data(c, pbuf, lbuf,
-				    psize, lsize) == 0 &&
-				    zio_decompress_data(c, pbuf2, lbuf2,
-				    psize, lsize) == 0 &&
+				if (zio_decompress_data(c, pabd,
+				    lbuf, psize, lsize) == 0 &&
+				    zio_decompress_data_buf(c, pbuf2,
+				    lbuf2, psize, lsize) == 0 &&
 				    bcmp(lbuf, lbuf2, lsize) == 0)
 					break;
 			}
@@ -3591,7 +3600,7 @@ zdb_read_block(char *thing, spa_t *spa)
 		buf = lbuf;
 		size = lsize;
 	} else {
-		buf = pbuf;
+		buf = abd_to_buf(pabd);
 		size = psize;
 	}
 
@@ -3609,7 +3618,7 @@ zdb_read_block(char *thing, spa_t *spa)
 		zdb_dump_block(thing, buf, size, flags);
 
 out:
-	umem_free(pbuf, SPA_MAXBLOCKSIZE);
+	abd_free(pabd);
 	umem_free(lbuf, SPA_MAXBLOCKSIZE);
 	free(dup);
 }
diff --git a/usr/src/cmd/zdb/zdb_il.c b/usr/src/cmd/zdb/zdb_il.c
index 583e422286..bc02b1b670 100644
--- a/usr/src/cmd/zdb/zdb_il.c
+++ b/usr/src/cmd/zdb/zdb_il.c
@@ -24,7 +24,7 @@
  */
 
 /*
- * Copyright (c) 2013, 2014 by Delphix. All rights reserved.
+ * Copyright (c) 2013, 2016 by Delphix. All rights reserved.
  */
 
 /*
@@ -41,6 +41,7 @@
 #include <sys/resource.h>
 #include <sys/zil.h>
 #include <sys/zil_impl.h>
+#include <sys/abd.h>
 
 extern uint8_t dump_opt[256];
 
@@ -117,13 +118,27 @@ zil_prt_rec_rename(zilog_t *zilog, int txtype, lr_rename_t *lr)
 }
 
 /* ARGSUSED */
+static int
+zil_prt_rec_write_cb(void *data, size_t len, void *unused)
+{
+	char *cdata = data;
+	for (int i = 0; i < len; i++) {
+		if (isprint(*cdata))
+			(void) printf("%c ", *cdata);
+		else
+			(void) printf("%2X", *cdata);
+		cdata++;
+	}
+	return (0);
+}
+
+/* ARGSUSED */
 static void
 zil_prt_rec_write(zilog_t *zilog, int txtype, lr_write_t *lr)
 {
-	char *data, *dlimit;
+	abd_t *data;
 	blkptr_t *bp = &lr->lr_blkptr;
 	zbookmark_phys_t zb;
-	char buf[SPA_MAXBLOCKSIZE];
 	int verbose = MAX(dump_opt['d'], dump_opt['i']);
 	int error;
 
@@ -144,7 +159,6 @@ zil_prt_rec_write(zilog_t *zilog, int txtype, lr_write_t *lr)
 		if (BP_IS_HOLE(bp)) {
 			(void) printf("\t\t\tLSIZE 0x%llx\n",
 			    (u_longlong_t)BP_GET_LSIZE(bp));
-			bzero(buf, sizeof (buf));
 			(void) printf("%s<hole>\n", prefix);
 			return;
 		}
@@ -157,28 +171,26 @@ zil_prt_rec_write(zilog_t *zilog, int txtype, lr_write_t *lr)
 		    lr->lr_foid, ZB_ZIL_LEVEL,
 		    lr->lr_offset / BP_GET_LSIZE(bp));
 
+		data = abd_alloc(BP_GET_LSIZE(bp), B_FALSE);
 		error = zio_wait(zio_read(NULL, zilog->zl_spa,
-		    bp, buf, BP_GET_LSIZE(bp), NULL, NULL,
+		    bp, data, BP_GET_LSIZE(bp), NULL, NULL,
 		    ZIO_PRIORITY_SYNC_READ, ZIO_FLAG_CANFAIL, &zb));
 		if (error)
-			return;
-		data = buf;
+			goto out;
 	} else {
-		data = (char *)(lr + 1);
+		/* data is stored after the end of the lr_write record */
+		data = abd_alloc(lr->lr_length, B_FALSE);
+		abd_copy_from_buf(data, lr + 1, lr->lr_length);
 	}
 
-	dlimit = data + MIN(lr->lr_length,
-	    (verbose < 6 ? 20 : SPA_MAXBLOCKSIZE));
-
 	(void) printf("%s", prefix);
-	while (data < dlimit) {
-		if (isprint(*data))
-			(void) printf("%c ", *data);
-		else
-			(void) printf("%2X", *data);
-		data++;
-	}
+	(void) abd_iterate_func(data,
+	    0, MIN(lr->lr_length, (verbose < 6 ? 20 : SPA_MAXBLOCKSIZE)),
+	    zil_prt_rec_write_cb, NULL);
 	(void) printf("\n");
+
+out:
+	abd_free(data);
 }
 
 /* ARGSUSED */
diff --git a/usr/src/cmd/ztest/ztest.c b/usr/src/cmd/ztest/ztest.c
index 75a3d5245f..16f79b52ef 100644
--- a/usr/src/cmd/ztest/ztest.c
+++ b/usr/src/cmd/ztest/ztest.c
@@ -111,6 +111,7 @@
 #include <sys/refcount.h>
 #include <sys/zfeature.h>
 #include <sys/dsl_userhold.h>
+#include <sys/abd.h>
 #include <stdio.h>
 #include <stdio_ext.h>
 #include <stdlib.h>
@@ -188,6 +189,7 @@ extern uint64_t metaslab_df_alloc_threshold;
 extern uint64_t zfs_deadman_synctime_ms;
 extern int metaslab_preload_limit;
 extern boolean_t zfs_compressed_arc_enabled;
+extern boolean_t zfs_abd_scatter_enabled;
 
 static ztest_shared_opts_t *ztest_shared_opts;
 static ztest_shared_opts_t ztest_opts;
@@ -5051,7 +5053,7 @@ ztest_ddt_repair(ztest_ds_t *zd, uint64_t id)
 	enum zio_checksum checksum = spa_dedup_checksum(spa);
 	dmu_buf_t *db;
 	dmu_tx_t *tx;
-	void *buf;
+	abd_t *abd;
 	blkptr_t blk;
 	int copies = 2 * ZIO_DEDUPDITTO_MIN;
 
@@ -5131,14 +5133,14 @@ ztest_ddt_repair(ztest_ds_t *zd, uint64_t id)
 	 * Damage the block.  Dedup-ditto will save us when we read it later.
 	 */
 	psize = BP_GET_PSIZE(&blk);
-	buf = zio_buf_alloc(psize);
-	ztest_pattern_set(buf, psize, ~pattern);
+	abd = abd_alloc_linear(psize, B_TRUE);
+	ztest_pattern_set(abd_to_buf(abd), psize, ~pattern);
 
 	(void) zio_wait(zio_rewrite(NULL, spa, 0, &blk,
-	    buf, psize, NULL, NULL, ZIO_PRIORITY_SYNC_WRITE,
+	    abd, psize, NULL, NULL, ZIO_PRIORITY_SYNC_WRITE,
 	    ZIO_FLAG_CANFAIL | ZIO_FLAG_INDUCE_DAMAGE, NULL));
 
-	zio_buf_free(buf, psize);
+	abd_free(abd);
 
 	(void) rw_unlock(&ztest_name_lock);
 }
@@ -5421,6 +5423,12 @@ ztest_resume_thread(void *arg)
 		 */
 		if (ztest_random(10) == 0)
 			zfs_compressed_arc_enabled = ztest_random(2);
+
+		/*
+		 * Periodically change the zfs_abd_scatter_enabled setting.
+		 */
+		if (ztest_random(10) == 0)
+			zfs_abd_scatter_enabled = ztest_random(2);
 	}
 	return (NULL);
 }
diff --git a/usr/src/common/zfs/zfs_fletcher.c b/usr/src/common/zfs/zfs_fletcher.c
index a58fa14b7c..c889169b42 100644
--- a/usr/src/common/zfs/zfs_fletcher.c
+++ b/usr/src/common/zfs/zfs_fletcher.c
@@ -24,6 +24,7 @@
  */
 /*
  * Copyright 2013 Saso Kiselkov. All rights reserved.
+ * Copyright (c) 2016 by Delphix. All rights reserved.
  */
 
 /*
@@ -133,17 +134,29 @@
 #include <sys/byteorder.h>
 #include <sys/zio.h>
 #include <sys/spa.h>
+#include <zfs_fletcher.h>
 
-/*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;
@@ -151,18 +164,33 @@ 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, size_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;
@@ -170,50 +198,23 @@ fletcher_2_byteswap(const void *buf, uint64_t size,
 	}
 
 	ZIO_SET_CHECKSUM(zcp, a0, a1, b0, b1);
+	return (0);
 }
 
 /*ARGSUSED*/
 void
-fletcher_4_native(const void *buf, uint64_t size,
+fletcher_2_byteswap(const void *buf, size_t size,
     const void *ctx_template, zio_cksum_t *zcp)
 {
-	const uint32_t *ip = buf;
-	const uint32_t *ipend = ip + (size / sizeof (uint32_t));
-	uint64_t a, b, c, d;
-
-	for (a = b = c = d = 0; ip < ipend; ip++) {
-		a += ip[0];
-		b += a;
-		c += b;
-		d += c;
-	}
-
-	ZIO_SET_CHECKSUM(zcp, a, b, c, d);
+	fletcher_init(zcp);
+	(void) fletcher_2_incremental_byteswap((void *) buf, size, zcp);
 }
 
-/*ARGSUSED*/
-void
-fletcher_4_byteswap(const void *buf, uint64_t size,
-    const void *ctx_template, zio_cksum_t *zcp)
+int
+fletcher_4_incremental_native(void *buf, size_t size, void *data)
 {
-	const uint32_t *ip = buf;
-	const uint32_t *ipend = ip + (size / sizeof (uint32_t));
-	uint64_t a, b, c, d;
+	zio_cksum_t *zcp = data;
 
-	for (a = b = c = d = 0; ip < ipend; ip++) {
-		a += BSWAP_32(ip[0]);
-		b += a;
-		c += b;
-		d += c;
-	}
-
-	ZIO_SET_CHECKSUM(zcp, a, b, c, d);
-}
-
-void
-fletcher_4_incremental_native(const void *buf, uint64_t size,
-    zio_cksum_t *zcp)
-{
 	const uint32_t *ip = buf;
 	const uint32_t *ipend = ip + (size / sizeof (uint32_t));
 	uint64_t a, b, c, d;
@@ -231,12 +232,23 @@ fletcher_4_incremental_native(const void *buf, uint64_t size,
 	}
 
 	ZIO_SET_CHECKSUM(zcp, a, b, c, d);
+	return (0);
 }
 
+/*ARGSUSED*/
 void
-fletcher_4_incremental_byteswap(const void *buf, uint64_t size,
-    zio_cksum_t *zcp)
+fletcher_4_native(const void *buf, size_t size,
+    const void *ctx_template, zio_cksum_t *zcp)
 {
+	fletcher_init(zcp);
+	(void) fletcher_4_incremental_native((void *) buf, size, zcp);
+}
+
+int
+fletcher_4_incremental_byteswap(void *buf, size_t size, void *data)
+{
+	zio_cksum_t *zcp = data;
+
 	const uint32_t *ip = buf;
 	const uint32_t *ipend = ip + (size / sizeof (uint32_t));
 	uint64_t a, b, c, d;
@@ -254,4 +266,14 @@ fletcher_4_incremental_byteswap(const void *buf, uint64_t size,
 	}
 
 	ZIO_SET_CHECKSUM(zcp, a, b, c, d);
+	return (0);
+}
+
+/*ARGSUSED*/
+void
+fletcher_4_byteswap(const void *buf, size_t size,
+    const void *ctx_template, zio_cksum_t *zcp)
+{
+	fletcher_init(zcp);
+	(void) fletcher_4_incremental_byteswap((void *) buf, size, zcp);
 }
diff --git a/usr/src/common/zfs/zfs_fletcher.h b/usr/src/common/zfs/zfs_fletcher.h
index a920cc816d..33c6c728cf 100644
--- a/usr/src/common/zfs/zfs_fletcher.h
+++ b/usr/src/common/zfs/zfs_fletcher.h
@@ -24,6 +24,7 @@
  */
 /*
  * Copyright 2013 Saso Kiselkov. All rights reserved.
+ * Copyright (c) 2016 by Delphix. All rights reserved.
  */
 
 #ifndef	_ZFS_FLETCHER_H
@@ -40,12 +41,15 @@ extern "C" {
  * fletcher checksum functions
  */
 
-void fletcher_2_native(const void *, uint64_t, const void *, zio_cksum_t *);
-void fletcher_2_byteswap(const void *, uint64_t, const void *, zio_cksum_t *);
-void fletcher_4_native(const void *, uint64_t, const void *, zio_cksum_t *);
-void fletcher_4_byteswap(const void *, uint64_t, const void *, zio_cksum_t *);
-void fletcher_4_incremental_native(const void *, uint64_t, zio_cksum_t *);
-void fletcher_4_incremental_byteswap(const void *, uint64_t, zio_cksum_t *);
+void fletcher_init(zio_cksum_t *);
+void fletcher_2_native(const void *, size_t, const void *, zio_cksum_t *);
+void fletcher_2_byteswap(const void *, size_t, const void *, zio_cksum_t *);
+int fletcher_2_incremental_native(void *, size_t, void *);
+int fletcher_2_incremental_byteswap(void *, size_t, void *);
+void fletcher_4_native(const void *, size_t, const void *, zio_cksum_t *);
+void fletcher_4_byteswap(const void *, size_t, const void *, zio_cksum_t *);
+int fletcher_4_incremental_native(void *, size_t, void *);
+int fletcher_4_incremental_byteswap(void *, size_t, void *);
 
 #ifdef	__cplusplus
 }
diff --git a/usr/src/lib/libzfs/common/libzfs_sendrecv.c b/usr/src/lib/libzfs/common/libzfs_sendrecv.c
index 2641d53e00..4e89dc053d 100644
--- a/usr/src/lib/libzfs/common/libzfs_sendrecv.c
+++ b/usr/src/lib/libzfs/common/libzfs_sendrecv.c
@@ -192,19 +192,19 @@ dump_record(dmu_replay_record_t *drr, 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(drr,
+	(void) fletcher_4_incremental_native(drr,
 	    offsetof(dmu_replay_record_t, drr_u.drr_checksum.drr_checksum), zc);
 	if (drr->drr_type != DRR_BEGIN) {
 		ASSERT(ZIO_CHECKSUM_IS_ZERO(&drr->drr_u.
 		    drr_checksum.drr_checksum));
 		drr->drr_u.drr_checksum.drr_checksum = *zc;
 	}
-	fletcher_4_incremental_native(&drr->drr_u.drr_checksum.drr_checksum,
-	    sizeof (zio_cksum_t), zc);
+	(void) fletcher_4_incremental_native(
+	    &drr->drr_u.drr_checksum.drr_checksum, sizeof (zio_cksum_t), zc);
 	if (write(outfd, drr, sizeof (*drr)) == -1)
 		return (errno);
 	if (payload_len != 0) {
-		fletcher_4_incremental_native(payload, payload_len, zc);
+		(void) fletcher_4_incremental_native(payload, payload_len, zc);
 		if (write(outfd, payload, payload_len) == -1)
 			return (errno);
 	}
@@ -2093,9 +2093,9 @@ recv_read(libzfs_handle_t *hdl, int fd, void *buf, int ilen,
 
 	if (zc) {
 		if (byteswap)
-			fletcher_4_incremental_byteswap(buf, ilen, zc);
+			(void) fletcher_4_incremental_byteswap(buf, ilen, zc);
 		else
-			fletcher_4_incremental_native(buf, ilen, zc);
+			(void) fletcher_4_incremental_native(buf, ilen, zc);
 	}
 	return (0);
 }
@@ -3649,7 +3649,8 @@ zfs_receive_impl(libzfs_handle_t *hdl, const char *tosnap,
 		 * recv_read() above; do it again correctly.
 		 */
 		bzero(&zcksum, sizeof (zio_cksum_t));
-		fletcher_4_incremental_byteswap(&drr, sizeof (drr), &zcksum);
+		(void) fletcher_4_incremental_byteswap(&drr,
+		    sizeof (drr), &zcksum);
 		flags->byteswap = B_TRUE;
 
 		drr.drr_type = BSWAP_32(drr.drr_type);
diff --git a/usr/src/lib/libzpool/common/llib-lzpool b/usr/src/lib/libzpool/common/llib-lzpool
index d0421bea94..3636b4e76e 100644
--- a/usr/src/lib/libzpool/common/llib-lzpool
+++ b/usr/src/lib/libzpool/common/llib-lzpool
@@ -61,6 +61,7 @@
 #include <sys/dsl_destroy.h>
 #include <sys/dsl_userhold.h>
 #include <sys/blkptr.h>
+#include <sys/abd.h>
 
 extern uint64_t metaslab_gang_bang;
 extern uint64_t metaslab_df_alloc_threshold;
@@ -68,3 +69,4 @@ extern boolean_t zfeature_checks_disable;
 extern uint64_t zfs_deadman_synctime_ms;
 extern int metaslab_preload_limit;
 extern boolean_t zfs_compressed_arc_enabled;
+extern boolean_t zfs_abd_scatter_enabled;
diff --git a/usr/src/pkg/manifests/system-test-zfstest.mf b/usr/src/pkg/manifests/system-test-zfstest.mf
index 114e9108df..7d2637a592 100644
--- a/usr/src/pkg/manifests/system-test-zfstest.mf
+++ b/usr/src/pkg/manifests/system-test-zfstest.mf
@@ -143,6 +143,7 @@ dir path=opt/zfs-tests/tests/functional/xattr
 dir path=opt/zfs-tests/tests/functional/zvol
 dir path=opt/zfs-tests/tests/functional/zvol/zvol_ENOSPC
 dir path=opt/zfs-tests/tests/functional/zvol/zvol_cli
+dir path=opt/zfs-tests/tests/functional/zvol/zvol_dump
 dir path=opt/zfs-tests/tests/functional/zvol/zvol_misc
 dir path=opt/zfs-tests/tests/functional/zvol/zvol_swap
 dir path=opt/zfs-tests/tests/perf
@@ -158,6 +159,7 @@ file path=opt/zfs-tests/bin/file_trunc mode=0555
 file path=opt/zfs-tests/bin/file_write mode=0555
 file path=opt/zfs-tests/bin/getholes mode=0555
 file path=opt/zfs-tests/bin/largest_file mode=0555
+file path=opt/zfs-tests/bin/memory_balloon mode=0555
 file path=opt/zfs-tests/bin/mkbusy mode=0555
 file path=opt/zfs-tests/bin/mkfiles mode=0555
 file path=opt/zfs-tests/bin/mkholes mode=0555
@@ -2261,6 +2263,8 @@ file path=opt/zfs-tests/tests/functional/zvol/zvol_cli/zvol_cli_002_pos \
 file path=opt/zfs-tests/tests/functional/zvol/zvol_cli/zvol_cli_003_neg \
     mode=0555
 file path=opt/zfs-tests/tests/functional/zvol/zvol_common.shlib mode=0444
+file path=opt/zfs-tests/tests/functional/zvol/zvol_dump/zvol_dump_raidz \
+    mode=0555
 file path=opt/zfs-tests/tests/functional/zvol/zvol_misc/cleanup mode=0555
 file path=opt/zfs-tests/tests/functional/zvol/zvol_misc/setup mode=0555
 file path=opt/zfs-tests/tests/functional/zvol/zvol_misc/zvol_misc_001_neg \
@@ -2302,14 +2306,18 @@ file path=opt/zfs-tests/tests/perf/regression/random_reads mode=0555
 file path=opt/zfs-tests/tests/perf/regression/random_readwrite mode=0555
 file path=opt/zfs-tests/tests/perf/regression/random_writes mode=0555
 file path=opt/zfs-tests/tests/perf/regression/sequential_reads mode=0555
-file path=opt/zfs-tests/tests/perf/regression/sequential_reads_cached \
+file path=opt/zfs-tests/tests/perf/regression/sequential_reads_arc_cached \
+    mode=0555
+file \
+    path=opt/zfs-tests/tests/perf/regression/sequential_reads_arc_cached_clone \
     mode=0555
-file path=opt/zfs-tests/tests/perf/regression/sequential_reads_cached_clone \
+file path=opt/zfs-tests/tests/perf/regression/sequential_reads_dbuf_cached \
     mode=0555
 file path=opt/zfs-tests/tests/perf/regression/sequential_writes mode=0555
 file path=opt/zfs-tests/tests/perf/regression/setup mode=0555
 file path=opt/zfs-tests/tests/perf/scripts/io.d mode=0444
 file path=opt/zfs-tests/tests/perf/scripts/prefetch_io.d mode=0444
+file path=opt/zfs-tests/tests/perf/scripts/profile.d mode=0444
 license cr_Sun license=cr_Sun
 license lic_CDDL license=lic_CDDL
 depend fmri=system/file-system/zfs/tests type=require
diff --git a/usr/src/test/zfs-tests/cmd/memory_balloon/Makefile b/usr/src/test/zfs-tests/cmd/memory_balloon/Makefile
new file mode 100644
index 0000000000..df1d370356
--- /dev/null
+++ b/usr/src/test/zfs-tests/cmd/memory_balloon/Makefile
@@ -0,0 +1,22 @@
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+
+#
+# Copyright (c) 2016 by Delphix. All rights reserved.
+#
+
+PROG = memory_balloon
+
+include $(SRC)/cmd/Makefile.cmd
+
+LINTFLAGS += -erroff=E_FUNC_SET_NOT_USED
+
+include ../Makefile.subdirs
diff --git a/usr/src/test/zfs-tests/cmd/memory_balloon/memory_balloon.c b/usr/src/test/zfs-tests/cmd/memory_balloon/memory_balloon.c
new file mode 100644
index 0000000000..958f6e6609
--- /dev/null
+++ b/usr/src/test/zfs-tests/cmd/memory_balloon/memory_balloon.c
@@ -0,0 +1,103 @@
+/*
+ * This file and its contents are supplied under the terms of the
+ * Common Development and Distribution License ("CDDL"), version 1.0.
+ * You may only use this file in accordance with the terms of version
+ * 1.0 of the CDDL.
+ *
+ * A full copy of the text of the CDDL should have accompanied this
+ * source.  A copy of the CDDL is also available via the Internet at
+ * http://www.illumos.org/license/CDDL.
+ */
+
+/*
+ * Copyright (c) 2016 by Delphix. All rights reserved.
+ */
+
+/*
+ * Steal memory from the kernel, forcing the ARC to decrease in size, and hold
+ * it until the process receives a signal.
+ */
+
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/shm.h>
+#include <strings.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+
+static void
+usage(char *progname)
+{
+	(void) fprintf(stderr, "Usage: %s -f <bytes>\n", progname);
+	exit(1);
+}
+
+static void
+fail(char *err, int rval)
+{
+	perror(err);
+	exit(rval);
+}
+
+static void
+daemonize(void)
+{
+	pid_t	pid;
+
+	if ((pid = fork()) < 0) {
+		fail("fork", 1);
+	} else if (pid != 0) {
+		(void) fprintf(stdout, "%ld\n", pid);
+		exit(0);
+	}
+
+	(void) setsid();
+	(void) close(0);
+	(void) close(1);
+	(void) close(2);
+}
+
+int
+main(int argc, char *argv[])
+{
+	int		c;
+	boolean_t	fflag = B_FALSE;
+	char		*prog = argv[0];
+	long long	size;
+	char		*stroll_leftovers;
+	int		shm_id;
+	void		*shm_attached;
+
+	while ((c = getopt(argc, argv, "f")) != -1) {
+		switch (c) {
+		/* Run in the foreground */
+		case 'f':
+			fflag = B_TRUE;
+			break;
+		default:
+			usage(prog);
+		}
+	}
+
+	argc -= optind;
+	argv += optind;
+
+	if (argc != 1)
+		usage(prog);
+	size = strtoll(argv[0], &stroll_leftovers, 10);
+	if (size <= 0)
+		fail("invalid size in bytes", 1);
+
+	if ((shm_id = shmget(IPC_PRIVATE, size, IPC_CREAT|IPC_EXCL)) == -1)
+		fail("shmget", 1);
+	if ((shm_attached = shmat(shm_id, NULL, SHM_SHARE_MMU)) == (void *)-1)
+		fail("shmat", 1);
+
+	if (fflag == B_FALSE)
+		daemonize();
+	(void) pause();
+
+	/* NOTREACHED */
+	return (0);
+}
diff --git a/usr/src/test/zfs-tests/runfiles/delphix.run b/usr/src/test/zfs-tests/runfiles/delphix.run
index a2f1b2c4b2..df1b6369b3 100644
--- a/usr/src/test/zfs-tests/runfiles/delphix.run
+++ b/usr/src/test/zfs-tests/runfiles/delphix.run
@@ -558,6 +558,11 @@ tests = ['zvol_ENOSPC_001_pos']
 [/opt/zfs-tests/tests/functional/zvol/zvol_cli]
 tests = ['zvol_cli_001_pos', 'zvol_cli_002_pos', 'zvol_cli_003_neg']
 
+[/opt/zfs-tests/tests/functional/zvol/zvol_dump]
+tests = ['zvol_dump_raidz']
+pre =
+post =
+
 [/opt/zfs-tests/tests/functional/zvol/zvol_misc]
 tests = ['zvol_misc_001_neg', 'zvol_misc_002_pos', 'zvol_misc_003_neg',
     'zvol_misc_004_pos', 'zvol_misc_005_neg', 'zvol_misc_006_pos']
diff --git a/usr/src/test/zfs-tests/runfiles/omnios.run b/usr/src/test/zfs-tests/runfiles/omnios.run
index 3982dd6ba8..952ab1503d 100644
--- a/usr/src/test/zfs-tests/runfiles/omnios.run
+++ b/usr/src/test/zfs-tests/runfiles/omnios.run
@@ -554,6 +554,11 @@ tests = ['zvol_ENOSPC_001_pos']
 [/opt/zfs-tests/tests/functional/zvol/zvol_cli]
 tests = ['zvol_cli_001_pos', 'zvol_cli_002_pos', 'zvol_cli_003_neg']
 
+[/opt/zfs-tests/tests/functional/zvol/zvol_dump]
+tests = ['zvol_dump_raidz']
+pre =
+post =
+
 [/opt/zfs-tests/tests/functional/zvol/zvol_misc]
 tests = ['zvol_misc_001_neg', 'zvol_misc_002_pos', 'zvol_misc_003_neg',
     'zvol_misc_004_pos', 'zvol_misc_005_neg', 'zvol_misc_006_pos']
diff --git a/usr/src/test/zfs-tests/runfiles/openindiana.run b/usr/src/test/zfs-tests/runfiles/openindiana.run
index 01a30c8c06..407af74e57 100644
--- a/usr/src/test/zfs-tests/runfiles/openindiana.run
+++ b/usr/src/test/zfs-tests/runfiles/openindiana.run
@@ -554,6 +554,11 @@ tests = ['zvol_ENOSPC_001_pos']
 [/opt/zfs-tests/tests/functional/zvol/zvol_cli]
 tests = ['zvol_cli_001_pos', 'zvol_cli_002_pos', 'zvol_cli_003_neg']
 
+[/opt/zfs-tests/tests/functional/zvol/zvol_dump]
+tests = ['zvol_dump_raidz']
+pre =
+post =
+
 [/opt/zfs-tests/tests/functional/zvol/zvol_misc]
 tests = ['zvol_misc_001_neg', 'zvol_misc_002_pos', 'zvol_misc_003_neg',
     'zvol_misc_004_pos', 'zvol_misc_005_neg', 'zvol_misc_006_pos']
diff --git a/usr/src/test/zfs-tests/runfiles/perf-regression.run b/usr/src/test/zfs-tests/runfiles/perf-regression.run
index 0095931ad5..dbb30f0327 100644
--- a/usr/src/test/zfs-tests/runfiles/perf-regression.run
+++ b/usr/src/test/zfs-tests/runfiles/perf-regression.run
@@ -10,7 +10,7 @@
 #
 
 #
-# Copyright (c) 2015 by Delphix. All rights reserved.
+# Copyright (c) 2015, 2016 by Delphix. All rights reserved.
 #
 
 [DEFAULT]
@@ -24,7 +24,7 @@ post = cleanup
 outputdir = /var/tmp/test_results
 
 [/opt/zfs-tests/tests/perf/regression]
-tests = ['sequential_writes', 'sequential_reads', 'sequential_reads_cached',
-    'sequential_reads_cached_clone', 'random_reads', 'random_writes',
-    'random_readwrite']
+tests = ['sequential_writes', 'sequential_reads', 'sequential_reads_arc_cached',
+    'sequential_reads_arc_cached_clone', 'sequential_reads_dbuf_cached',
+    'random_reads', 'random_writes', 'random_readwrite']
 post =
diff --git a/usr/src/test/zfs-tests/tests/functional/mdb/mdb_001_pos.ksh b/usr/src/test/zfs-tests/tests/functional/mdb/mdb_001_pos.ksh
index a4f90be49b..7f6faf690e 100644
--- a/usr/src/test/zfs-tests/tests/functional/mdb/mdb_001_pos.ksh
+++ b/usr/src/test/zfs-tests/tests/functional/mdb/mdb_001_pos.ksh
@@ -49,26 +49,51 @@ function cleanup
 verify_runnable "global"
 log_onexit cleanup
 
-OUTFILE='/var/tmp/mdb-outfile'
-set -A dcmds "::walk spa" \
-	"::walk spa | ::spa " \
-	"::walk spa | ::spa -c" \
-	"::walk spa | ::spa -v" \
-	"::walk spa | ::spa_config" \
-	"::walk spa | ::spa_space" \
-	"::walk spa | ::spa_space -b" \
-	"::walk spa | ::spa_vdevs" \
-	"::walk spa | ::walk metaslab" \
-	"::walk spa | ::print struct spa spa_root_vdev | ::vdev" \
-	"::walk spa | ::print struct spa spa_root_vdev | ::vdev -re" \
+tmpfile=$(mktemp)
+log_must zpool scrub $TESTPOOL
+
+typeset spa=$(mdb -ke "::spa" | awk "/$TESTPOOL/ {print \$1}")
+typeset off_ub=$(mdb -ke "::offsetof spa_t spa_uberblock | =J")
+typeset off_rbp=$(mdb -ke "::offsetof uberblock_t ub_rootbp | =J")
+typeset bp=$(mdb -ke "$spa + $off_ub + $off_rbp =J")
+
+# dcmds and walkers skipped due to being DEBUG only or difficult to run:
+# ::zfs_params
+# ::refcount
+
+set -A dcmds "::abuf_find 1 2" \
+	"::arc" \
+	"::arc -b" \
+	"::arc_compression_stats" \
+	"$bp ::blkptr" \
+	"$bp ::dva" \
+	"::walk spa" \
+	"::spa" \
+	"$spa ::spa " \
+	"$spa ::spa -c" \
+	"$spa ::spa -h" \
+	"$spa ::spa -v" \
+	"$spa ::spa -Mmh" \
+	"$spa ::spa_config" \
+	"$spa ::spa_space" \
+	"$spa ::spa_space -b" \
+	"$spa ::spa_vdevs" \
+	"$spa ::print spa_t spa_root_vdev | ::vdev" \
+	"$spa ::print spa_t spa_root_vdev | ::vdev -re" \
+	"$spa ::print -a spa_t spa_dsl_pool->dp_dirty_datasets | ::walk txg_list" \
+	"$spa ::print -a spa_t spa_uberblock.ub_rootbp | ::blkptr" \
+	"$spa ::walk metaslab" \
+	"$spa ::walk metaslab | ::head -1 | ::metaslab_weight" \
+	"$spa ::walk metaslab | ::head -1 | ::metaslab_trace" \
+	"$spa ::walk zio_root | ::zio -c" \
+	"$spa ::walk zio_root | ::zio -r" \
+	"$spa ::walk zms_freelist"
+	"$spa ::zfs_blkstats -v" \
 	"::dbufs" \
 	"::dbufs -n mos -o mdn -l 0 -b 0" \
 	"::dbufs | ::dbuf" \
 	"::dbuf_stats" \
-	"::abuf_find 1 2" \
-        "::walk spa | ::print -a struct spa spa_uberblock.ub_rootbp | ::blkptr" \
-        "::walk spa | ::print -a struct spa spa_dsl_pool->dp_dirty_datasets | ::walk txg_list" \
-        "::walk spa | ::walk zms_freelist"
+	"dbuf_cache ::walk multilist"
 #
 # The commands above were supplied by the ZFS development team. The idea is to
 # do as much checking as possible without the need to hardcode addresses.
diff --git a/usr/src/test/zfs-tests/tests/functional/zvol/zvol_dump/Makefile b/usr/src/test/zfs-tests/tests/functional/zvol/zvol_dump/Makefile
new file mode 100644
index 0000000000..84101e8f9c
--- /dev/null
+++ b/usr/src/test/zfs-tests/tests/functional/zvol/zvol_dump/Makefile
@@ -0,0 +1,21 @@
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+
+#
+# Copyright (c) 2017 by Delphix. All rights reserved.
+#
+
+include $(SRC)/Makefile.master
+
+ROOTOPTPKG = $(ROOT)/opt/zfs-tests
+TARGETDIR = $(ROOTOPTPKG)/tests/functional/zvol/zvol_dump
+
+include $(SRC)/test/zfs-tests/Makefile.com
diff --git a/usr/src/test/zfs-tests/tests/functional/zvol/zvol_dump/zvol_dump_raidz.ksh b/usr/src/test/zfs-tests/tests/functional/zvol/zvol_dump/zvol_dump_raidz.ksh
new file mode 100644
index 0000000000..836ae9c40a
--- /dev/null
+++ b/usr/src/test/zfs-tests/tests/functional/zvol/zvol_dump/zvol_dump_raidz.ksh
@@ -0,0 +1,54 @@
+#!/usr/bin/ksh -p
+
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+
+#
+# Copyright (c) 2017 by Delphix. All rights reserved.
+#
+
+. $STF_SUITE/include/libtest.shlib
+
+#
+# DESCRIPTION:
+# Attempt to access a dump device on a RAID-Z pool.
+#
+# STRATEGY:
+# 1. Create a RAID-Z pool.
+# 2. Create a zvol on that pool called "dump".
+# 3. Configure it with "dumpadm".
+# 4. Attempt to issue reads and writes to it.
+#
+
+# Save the current dump device so we can restore it after the test.
+orig_dump_device=$(dumpadm | awk '/Dump device/ { print $3 }')
+
+function cleanup
+{
+	log_must dumpadm -u -d $orig_dump_device
+	log_must zpool destroy -f $TESTPOOL
+}
+
+log_onexit cleanup
+
+DISK1="$(echo $DISKS | cut -d' ' -f1)"
+DISK2="$(echo $DISKS | cut -d' ' -f2)"
+DISK3="$(echo $DISKS | cut -d' ' -f3)"
+
+log_must zpool create -f $TESTPOOL raidz $DISK1 $DISK2 $DISK3
+log_must zfs create -V 8G $TESTPOOL/dump
+
+log_must dumpadm -u -d /dev/zvol/dsk/$TESTPOOL/dump
+
+log_must dd if=/dev/zvol/dsk/$TESTPOOL/dump of=/dev/null bs=1M count=1
+log_must dd if=/dev/urandom of=/dev/zvol/dsk/$TESTPOOL/dump bs=1M count=1
+
+log_pass "Reads and writes to the dump device on a RAID-Z pool were successful"
diff --git a/usr/src/test/zfs-tests/tests/perf/perf.shlib b/usr/src/test/zfs-tests/tests/perf/perf.shlib
index 72fc803345..24a85ba700 100644
--- a/usr/src/test/zfs-tests/tests/perf/perf.shlib
+++ b/usr/src/test/zfs-tests/tests/perf/perf.shlib
@@ -182,6 +182,18 @@ function get_max_arc_size
 	echo $max_arc_size
 }
 
+function get_max_dbuf_cache_size
+{
+	typeset -l max_dbuf_cache_size=$(dtrace -qn 'BEGIN {
+	    printf("%u\n", `dbuf_cache_max_bytes);
+	    exit(0);
+	}')
+
+	[[ $? -eq 0 ]] || log_fail "get_max_dbuf_cache_size failed"
+
+	echo $max_dbuf_cache_size
+}
+
 # Create a file with some information about how this system is configured.
 function get_system_config
 {
diff --git a/usr/src/test/zfs-tests/tests/perf/regression/random_reads.ksh b/usr/src/test/zfs-tests/tests/perf/regression/random_reads.ksh
index abf05ca719..655366e00c 100644
--- a/usr/src/test/zfs-tests/tests/perf/regression/random_reads.ksh
+++ b/usr/src/test/zfs-tests/tests/perf/regression/random_reads.ksh
@@ -69,8 +69,9 @@ log_must fio $FIO_SCRIPTS/mkfiles.fio
 # Set up the scripts and output files that will log performance data.
 lun_list=$(pool_to_lun_list $PERFPOOL)
 log_note "Collecting backend IO stats with lun list $lun_list"
-export collect_scripts=("$PERF_SCRIPTS/io.d $PERFPOOL $lun_list 1" "io"
-    "vmstat 1" "vmstat" "mpstat 1" "mpstat" "iostat -xcnz 1" "iostat")
+export collect_scripts=("dtrace -s $PERF_SCRIPTS/io.d $PERFPOOL $lun_list 1"
+    "io" "vmstat 1" "vmstat" "mpstat 1" "mpstat" "iostat -xcnz 1" "iostat"
+    "dtrace -s $PERF_SCRIPTS/profile.d" "profile" "kstat zfs:0 1" "kstat")
 
 log_note "Random reads with $PERF_RUNTYPE settings"
 do_fio_run random_reads.fio false true
diff --git a/usr/src/test/zfs-tests/tests/perf/regression/random_readwrite.ksh b/usr/src/test/zfs-tests/tests/perf/regression/random_readwrite.ksh
index 2422f9c658..f41a2b526e 100644
--- a/usr/src/test/zfs-tests/tests/perf/regression/random_readwrite.ksh
+++ b/usr/src/test/zfs-tests/tests/perf/regression/random_readwrite.ksh
@@ -69,8 +69,9 @@ log_must fio $FIO_SCRIPTS/mkfiles.fio
 # Set up the scripts and output files that will log performance data.
 lun_list=$(pool_to_lun_list $PERFPOOL)
 log_note "Collecting backend IO stats with lun list $lun_list"
-export collect_scripts=("$PERF_SCRIPTS/io.d $PERFPOOL $lun_list 1" "io"
-    "vmstat 1" "vmstat" "mpstat 1" "mpstat" "iostat -xcnz 1" "iostat")
+export collect_scripts=("dtrace -s $PERF_SCRIPTS/io.d $PERFPOOL $lun_list 1"
+    "io" "vmstat 1" "vmstat" "mpstat 1" "mpstat" "iostat -xcnz 1" "iostat"
+    "dtrace -s $PERF_SCRIPTS/profile.d" "profile" "kstat zfs:0 1" "kstat")
 
 log_note "Random reads and writes with $PERF_RUNTYPE settings"
 do_fio_run random_readwrite.fio false true
diff --git a/usr/src/test/zfs-tests/tests/perf/regression/random_writes.ksh b/usr/src/test/zfs-tests/tests/perf/regression/random_writes.ksh
index c48ae76140..9e201a827c 100644
--- a/usr/src/test/zfs-tests/tests/perf/regression/random_writes.ksh
+++ b/usr/src/test/zfs-tests/tests/perf/regression/random_writes.ksh
@@ -61,8 +61,9 @@ fi
 # Set up the scripts and output files that will log performance data.
 lun_list=$(pool_to_lun_list $PERFPOOL)
 log_note "Collecting backend IO stats with lun list $lun_list"
-export collect_scripts=("$PERF_SCRIPTS/io.d $PERFPOOL $lun_list 1" "io"
-    "vmstat 1" "vmstat" "mpstat 1" "mpstat" "iostat -xcnz 1" "iostat")
+export collect_scripts=("dtrace -s $PERF_SCRIPTS/io.d $PERFPOOL $lun_list 1"
+    "io" "vmstat 1" "vmstat" "mpstat 1" "mpstat" "iostat -xcnz 1" "iostat"
+    "dtrace -s $PERF_SCRIPTS/profile.d" "profile" "kstat zfs:0 1" "kstat")
 
 log_note "Random writes with $PERF_RUNTYPE settings"
 do_fio_run random_writes.fio true false
diff --git a/usr/src/test/zfs-tests/tests/perf/regression/sequential_reads.ksh b/usr/src/test/zfs-tests/tests/perf/regression/sequential_reads.ksh
index 60083c8673..580f2d94e4 100644
--- a/usr/src/test/zfs-tests/tests/perf/regression/sequential_reads.ksh
+++ b/usr/src/test/zfs-tests/tests/perf/regression/sequential_reads.ksh
@@ -69,9 +69,10 @@ log_must fio $FIO_SCRIPTS/mkfiles.fio
 # Set up the scripts and output files that will log performance data.
 lun_list=$(pool_to_lun_list $PERFPOOL)
 log_note "Collecting backend IO stats with lun list $lun_list"
-export collect_scripts=("$PERF_SCRIPTS/io.d $PERFPOOL $lun_list 1" "io"
-    "$PERF_SCRIPTS/prefetch_io.d $PERFPOOL 1" "prefetch" "vmstat 1" "vmstat"
-    "mpstat 1" "mpstat" "iostat -xcnz 1" "iostat")
+export collect_scripts=("dtrace -s $PERF_SCRIPTS/io.d $PERFPOOL $lun_list 1"
+    "io" "dtrace -Cs $PERF_SCRIPTS/prefetch_io.d $PERFPOOL 1" "prefetch"
+    "vmstat 1" "vmstat" "mpstat 1" "mpstat" "iostat -xcnz 1" "iostat"
+    "dtrace -s $PERF_SCRIPTS/profile.d" "profile" "kstat zfs:0 1" "kstat")
 
 log_note "Sequential reads with $PERF_RUNTYPE settings"
 do_fio_run sequential_reads.fio false true
diff --git a/usr/src/test/zfs-tests/tests/perf/regression/sequential_reads_cached.ksh b/usr/src/test/zfs-tests/tests/perf/regression/sequential_reads_arc_cached.ksh
index b4365c0871..97bb8bdc31 100644
--- a/usr/src/test/zfs-tests/tests/perf/regression/sequential_reads_cached.ksh
+++ b/usr/src/test/zfs-tests/tests/perf/regression/sequential_reads_arc_cached.ksh
@@ -68,9 +68,10 @@ log_must fio $FIO_SCRIPTS/mkfiles.fio
 # Set up the scripts and output files that will log performance data.
 lun_list=$(pool_to_lun_list $PERFPOOL)
 log_note "Collecting backend IO stats with lun list $lun_list"
-export collect_scripts=("$PERF_SCRIPTS/io.d $PERFPOOL $lun_list 1" "io"
-    "$PERF_SCRIPTS/prefetch_io.d $PERFPOOL 1" "prefetch" "vmstat 1" "vmstat"
-    "mpstat 1" "mpstat" "iostat -xcnz 1" "iostat")
+export collect_scripts=("dtrace -s $PERF_SCRIPTS/io.d $PERFPOOL $lun_list 1"
+    "io" "dtrace -Cs $PERF_SCRIPTS/prefetch_io.d $PERFPOOL 1" "prefetch"
+    "vmstat 1" "vmstat" "mpstat 1" "mpstat" "iostat -xcnz 1" "iostat"
+    "dtrace -s $PERF_SCRIPTS/profile.d" "profile" "kstat zfs:0 1" "kstat")
 
 log_note "Sequential cached reads with $PERF_RUNTYPE settings"
 do_fio_run sequential_reads.fio false false
diff --git a/usr/src/test/zfs-tests/tests/perf/regression/sequential_reads_cached_clone.ksh b/usr/src/test/zfs-tests/tests/perf/regression/sequential_reads_arc_cached_clone.ksh
index c656eb4643..cfc748c843 100644
--- a/usr/src/test/zfs-tests/tests/perf/regression/sequential_reads_cached_clone.ksh
+++ b/usr/src/test/zfs-tests/tests/perf/regression/sequential_reads_arc_cached_clone.ksh
@@ -84,9 +84,10 @@ export TESTFS=$PERFPOOL/$TESTCLONE
 # Set up the scripts and output files that will log performance data.
 lun_list=$(pool_to_lun_list $PERFPOOL)
 log_note "Collecting backend IO stats with lun list $lun_list"
-export collect_scripts=("$PERF_SCRIPTS/io.d $PERFPOOL $lun_list 1" "io"
-    "$PERF_SCRIPTS/prefetch_io.d $PERFPOOL 1" "prefetch" "vmstat 1" "vmstat"
-    "mpstat 1" "mpstat" "iostat -xcnz 1" "iostat")
+export collect_scripts=("dtrace -s $PERF_SCRIPTS/io.d $PERFPOOL $lun_list 1"
+    "io" "dtrace -Cs $PERF_SCRIPTS/prefetch_io.d $PERFPOOL 1" "prefetch"
+    "vmstat 1" "vmstat" "mpstat 1" "mpstat" "iostat -xcnz 1" "iostat"
+    "dtrace -s $PERF_SCRIPTS/profile.d" "profile" "kstat zfs:0 1" "kstat")
 
 log_note "Sequential cached reads from $TESTFS with $PERF_RUNTYPE settings"
 do_fio_run sequential_reads.fio false false
diff --git a/usr/src/test/zfs-tests/tests/perf/regression/sequential_reads_dbuf_cached.ksh b/usr/src/test/zfs-tests/tests/perf/regression/sequential_reads_dbuf_cached.ksh
new file mode 100644
index 0000000000..f7ea4b75c6
--- /dev/null
+++ b/usr/src/test/zfs-tests/tests/perf/regression/sequential_reads_dbuf_cached.ksh
@@ -0,0 +1,82 @@
+#!/usr/bin/ksh
+
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+
+#
+# Copyright (c) 2016 by Delphix. All rights reserved.
+#
+
+#
+# Description:
+# Trigger fio runs using the sequential_reads job file. The number of runs and
+# data collected is determined by the PERF_* variables. See do_fio_run for
+# details about these variables.
+#
+# The files to read from are created prior to the first fio run, and used
+# for all fio runs. The ARC is not cleared to ensure that all data is cached.
+#
+# This is basically a copy of the sequential_reads_cached test case, but with
+# a smaller dateset so that we can fit everything into the decompressed, linear
+# space in the dbuf cache.
+#
+
+. $STF_SUITE/include/libtest.shlib
+. $STF_SUITE/tests/perf/perf.shlib
+
+function cleanup
+{
+	log_must zfs destroy $TESTFS
+}
+
+log_assert "Measure IO stats during sequential read load"
+log_onexit cleanup
+
+export TESTFS=$PERFPOOL/testfs
+recreate_perfpool
+log_must zfs create $PERF_FS_OPTS $TESTFS
+
+# Ensure the working set can be cached in the dbuf cache.
+export TOTAL_SIZE=$(($(get_max_dbuf_cache_size) * 3 / 4))
+
+# Variables for use by fio.
+if [[ -n $PERF_REGRESSION_WEEKLY ]]; then
+	export PERF_RUNTIME=${PERF_RUNTIME:-$PERF_RUNTIME_WEEKLY}
+	export PERF_RUNTYPE=${PERF_RUNTYPE:-'weekly'}
+	export PERF_NTHREADS=${PERF_NTHREADS:-'16 64'}
+	export PERF_SYNC_TYPES=${PERF_SYNC_TYPES:-'1'}
+	export PERF_IOSIZES=${PERF_IOSIZES:-'64k'}
+elif [[ -n $PERF_REGRESSION_NIGHTLY ]]; then
+	export PERF_RUNTIME=${PERF_RUNTIME:-$PERF_RUNTIME_NIGHTLY}
+	export PERF_RUNTYPE=${PERF_RUNTYPE:-'nightly'}
+	export PERF_NTHREADS=${PERF_NTHREADS:-'64'}
+	export PERF_SYNC_TYPES=${PERF_SYNC_TYPES:-'1'}
+	export PERF_IOSIZES=${PERF_IOSIZES:-'64k'}
+fi
+
+# Layout the files to be used by the read tests. Create as many files as the
+# largest number of threads. An fio run with fewer threads will use a subset
+# of the available files.
+export NUMJOBS=$(get_max $PERF_NTHREADS)
+export FILE_SIZE=$((TOTAL_SIZE / NUMJOBS))
+log_must fio $FIO_SCRIPTS/mkfiles.fio
+
+# Set up the scripts and output files that will log performance data.
+lun_list=$(pool_to_lun_list $PERFPOOL)
+log_note "Collecting backend IO stats with lun list $lun_list"
+export collect_scripts=("dtrace -s $PERF_SCRIPTS/io.d $PERFPOOL $lun_list 1"
+    "io" "dtrace -Cs $PERF_SCRIPTS/prefetch_io.d $PERFPOOL 1" "prefetch"
+    "vmstat 1" "vmstat" "mpstat 1" "mpstat" "iostat -xcnz 1" "iostat"
+    "dtrace -s $PERF_SCRIPTS/profile.d" "profile" "kstat zfs:0 1" "kstat")
+
+log_note "Sequential cached reads with $PERF_RUNTYPE settings"
+do_fio_run sequential_reads.fio false false
+log_pass "Measure IO stats during sequential cached read load"
diff --git a/usr/src/test/zfs-tests/tests/perf/regression/sequential_writes.ksh b/usr/src/test/zfs-tests/tests/perf/regression/sequential_writes.ksh
index e2f2cca0d2..493a3d18b7 100644
--- a/usr/src/test/zfs-tests/tests/perf/regression/sequential_writes.ksh
+++ b/usr/src/test/zfs-tests/tests/perf/regression/sequential_writes.ksh
@@ -61,8 +61,9 @@ fi
 # Set up the scripts and output files that will log performance data.
 lun_list=$(pool_to_lun_list $PERFPOOL)
 log_note "Collecting backend IO stats with lun list $lun_list"
-export collect_scripts=("$PERF_SCRIPTS/io.d $PERFPOOL $lun_list 1" "io"
-    "vmstat 1" "vmstat" "mpstat 1" "mpstat" "iostat -xcnz 1" "iostat")
+export collect_scripts=("dtrace -s $PERF_SCRIPTS/io.d $PERFPOOL $lun_list 1"
+    "io" "vmstat 1" "vmstat" "mpstat 1" "mpstat" "iostat -xcnz 1" "iostat"
+    "dtrace -s $PERF_SCRIPTS/profile.d" "profile" "kstat zfs:0 1" "kstat")
 
 log_note "Sequential writes with $PERF_RUNTYPE settings"
 do_fio_run sequential_writes.fio true false
diff --git a/usr/src/test/zfs-tests/tests/perf/scripts/profile.d b/usr/src/test/zfs-tests/tests/perf/scripts/profile.d
new file mode 100644
index 0000000000..e7fbd1fca5
--- /dev/null
+++ b/usr/src/test/zfs-tests/tests/perf/scripts/profile.d
@@ -0,0 +1,37 @@
+#!/usr/sbin/dtrace -s
+
+/*
+ * This file and its contents are supplied under the terms of the
+ * Common Development and Distribution License ("CDDL"), version 1.0.
+ * You may only use this file in accordance with the terms of version
+ * 1.0 of the CDDL.
+ *
+ * A full copy of the text of the CDDL should have accompanied this
+ * source.  A copy of the CDDL is also available via the Internet at
+ * http://www.illumos.org/license/CDDL.
+ */
+
+/*
+ * Copyright (c) 2016 by Delphix. All rights reserved.
+ */
+
+#pragma D option stackframes=100
+
+/*
+ * @stacks: The number of times a stack has been recorded
+ */
+
+profile-997
+/ arg0 /
+{
+	@stacks[stack()] = count();
+}
+
+ERROR
+{
+    trace(arg1);
+    trace(arg2);
+    trace(arg3);
+    trace(arg4);
+    trace(arg5);
+}
diff --git a/usr/src/uts/common/Makefile.files b/usr/src/uts/common/Makefile.files
index b87e9e258e..873e5755cc 100644
--- a/usr/src/uts/common/Makefile.files
+++ b/usr/src/uts/common/Makefile.files
@@ -1349,6 +1349,7 @@ SMBFS_OBJS +=	smbfs_vfsops.o	smbfs_vnops.o	smbfs_node.o	\
 BOOTFS_OBJS +=	bootfs_construct.o bootfs_vfsops.o bootfs_vnops.o
 
 ZFS_COMMON_OBJS +=		\
+	abd.o			\
 	arc.o			\
 	blkptr.o		\
 	bplist.o		\
diff --git a/usr/src/uts/common/fs/zfs/abd.c b/usr/src/uts/common/fs/zfs/abd.c
new file mode 100644
index 0000000000..932ba800ed
--- /dev/null
+++ b/usr/src/uts/common/fs/zfs/abd.c
@@ -0,0 +1,940 @@
+/*
+ * This file and its contents are supplied under the terms of the
+ * Common Development and Distribution License ("CDDL"), version 1.0.
+ * You may only use this file in accordance with the terms of version
+ * 1.0 of the CDDL.
+ *
+ * A full copy of the text of the CDDL should have accompanied this
+ * source.  A copy of the CDDL is also available via the Internet at
+ * http://www.illumos.org/license/CDDL.
+ */
+
+/*
+ * 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 |
+ *                                                         +-----------+
+ *
+ * Using a large proportion of scattered ABDs decreases ARC fragmentation since
+ * when we are at the limit of allocatable space, using equal-size chunks will
+ * allow us to quickly reclaim enough space for a new large allocation (assuming
+ * it is also scattered).
+ *
+ * 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>
+
+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)
+
+/*
+ * It is possible to make all future ABDs be linear by setting this to B_FALSE.
+ * Otherwise, ABDs are allocated scattered by default unless the caller uses
+ * abd_alloc_linear().
+ */
+boolean_t zfs_abd_scatter_enabled = B_TRUE;
+
+/*
+ * The size of the chunks ABD allocates. Because the sizes allocated from the
+ * kmem_cache can't change, this tunable can only be modified at boot. Changing
+ * it at runtime would cause ABD iteration to work incorrectly for ABDs which
+ * were allocated with the old size, so a safeguard has been put in place which
+ * will cause the machine to panic if you change it and try to access the data
+ * within a scattered ABD.
+ */
+size_t zfs_abd_chunk_size = 4096;
+
+#ifdef _KERNEL
+extern vmem_t *zio_alloc_arena;
+#endif
+
+kmem_cache_t *abd_chunk_cache;
+static kstat_t *abd_ksp;
+
+static void *
+abd_alloc_chunk()
+{
+	void *c = kmem_cache_alloc(abd_chunk_cache, KM_PUSHPAGE);
+	ASSERT3P(c, !=, NULL);
+	return (c);
+}
+
+static void
+abd_free_chunk(void *c)
+{
+	kmem_cache_free(abd_chunk_cache, c);
+}
+
+void
+abd_init(void)
+{
+	vmem_t *data_alloc_arena = NULL;
+
+#ifdef _KERNEL
+	data_alloc_arena = zio_alloc_arena;
+#endif
+
+	/*
+	 * Since ABD chunks do not appear in crash dumps, we pass KMC_NOTOUCH
+	 * so that no allocator metadata is stored with the buffers.
+	 */
+	abd_chunk_cache = kmem_cache_create("abd_chunk", zfs_abd_chunk_size, 0,
+	    NULL, NULL, NULL, NULL, data_alloc_arena, KMC_NOTOUCH);
+
+	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;
+	}
+
+	kmem_cache_destroy(abd_chunk_cache);
+	abd_chunk_cache = NULL;
+}
+
+static inline size_t
+abd_chunkcnt_for_bytes(size_t size)
+{
+	return (P2ROUNDUP(size, zfs_abd_chunk_size) / zfs_abd_chunk_size);
+}
+
+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 {
+		ASSERT3U(abd->abd_u.abd_scatter.abd_offset, <,
+		    zfs_abd_chunk_size);
+		size_t n = abd_scatter_chunkcnt(abd);
+		for (int 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)
+{
+	if (!zfs_abd_scatter_enabled)
+		return (abd_alloc_linear(size, is_metadata));
+
+	VERIFY3U(size, <=, SPA_MAXBLOCKSIZE);
+
+	size_t n = abd_chunkcnt_for_bytes(size);
+	abd_t *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 = zfs_abd_chunk_size;
+
+	for (int 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 * zfs_abd_chunk_size - size);
+
+	return (abd);
+}
+
+static void
+abd_free_scatter(abd_t *abd)
+{
+	size_t n = abd_scatter_chunkcnt(abd);
+	for (int 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 * zfs_abd_chunk_size);
+
+	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.
+ *
+ * Currently 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().
+ */
+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 / zfs_abd_chunk_size);
+
+		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 % zfs_abd_chunk_size;
+		abd->abd_u.abd_scatter.abd_chunk_size = zfs_abd_chunk_size;
+
+		/* 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 /
+		    zfs_abd_chunk_size],
+		    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) % zfs_abd_chunk_size);
+}
+
+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) / zfs_abd_chunk_size);
+}
+
+/*
+ * 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);
+
+	/* Panic if someone has changed zfs_abd_chunk_size */
+	IMPLY(!abd_is_linear(aiter->iter_abd), zfs_abd_chunk_size ==
+	    aiter->iter_abd->abd_u.abd_scatter.abd_chunk_size);
+
+	/* 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 = zfs_abd_chunk_size - offset;
+		paddr = 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;
+
+	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) {
+		abd_iter_map(&aiter);
+
+		size_t 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) {
+		abd_iter_map(&daiter);
+		abd_iter_map(&saiter);
+
+		size_t dlen = MIN(daiter.iter_mapsize, size);
+		size_t slen = MIN(saiter.iter_mapsize, size);
+		size_t 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 first size bytes of two ABDs.
+ */
+int
+abd_cmp(abd_t *dabd, abd_t *sabd, size_t size)
+{
+	return (abd_iterate_func2(dabd, sabd, 0, 0, size, abd_cmp_cb, NULL));
+}
diff --git a/usr/src/uts/common/fs/zfs/arc.c b/usr/src/uts/common/fs/zfs/arc.c
index cb645dc39e..328c332ae4 100644
--- a/usr/src/uts/common/fs/zfs/arc.c
+++ b/usr/src/uts/common/fs/zfs/arc.c
@@ -128,14 +128,14 @@
  * 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
@@ -174,7 +174,7 @@
  *   | 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 |
@@ -191,8 +191,8 @@
  * 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
@@ -216,7 +216,7 @@
  *                |           |                 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   +-+
@@ -230,19 +230,19 @@
  *                                    |                    +------+     |
  *                                    +---------------------------------+
  *
- * 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
@@ -263,7 +263,9 @@
 #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>
@@ -299,7 +301,7 @@ int zfs_arc_evict_batch_limit = 10;
 /* number of seconds before growing cache again */
 static int		arc_grow_retry = 60;
 
-/* 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 */
@@ -462,13 +464,13 @@ 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.
 	 */
@@ -882,7 +884,7 @@ typedef struct l1arc_buf_hdr {
 	refcount_t		b_refcnt;
 
 	arc_callback_t		*b_acb;
-	void			*b_pdata;
+	abd_t			*b_pabd;
 } l1arc_buf_hdr_t;
 
 typedef struct l2arc_dev l2arc_dev_t;
@@ -1082,7 +1084,7 @@ typedef struct l2arc_write_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;
@@ -1092,10 +1094,14 @@ 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();
 static void arc_buf_watch(arc_buf_t *);
@@ -1435,7 +1441,9 @@ 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));
@@ -1539,7 +1547,8 @@ arc_cksum_is_equal(arc_buf_hdr_t *hdr, zio_t *zio)
 		uint64_t csize;
 
 		void *cbuf = zio_buf_alloc(HDR_GET_PSIZE(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)) {
 			/*
@@ -1574,7 +1583,7 @@ 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);
@@ -1872,7 +1881,7 @@ 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 {
@@ -1924,7 +1933,7 @@ 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));
 
 			/*
@@ -1961,7 +1970,7 @@ 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)
@@ -1993,14 +2002,14 @@ 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);
 	}
@@ -2028,14 +2037,14 @@ 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);
 	}
@@ -2132,7 +2141,7 @@ 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;
@@ -2202,7 +2211,7 @@ 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 {
 			uint32_t buffers = 0;
 
@@ -2231,7 +2240,7 @@ 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 {
@@ -2244,7 +2253,7 @@ 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,
@@ -2284,7 +2293,7 @@ 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);
 		}
@@ -2366,7 +2375,7 @@ 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)
@@ -2443,20 +2452,23 @@ arc_buf_alloc_impl(arc_buf_hdr_t *hdr, void *tag, boolean_t compressed,
 	/*
 	 * If the hdr's data can be shared then we share the data buffer and
 	 * set the appropriate bit in the hdr's b_flags to indicate the hdr is
-	 * sharing it's b_pdata with the arc_buf_t. Otherwise, we allocate a new
+	 * sharing it's b_pabd with the arc_buf_t. Otherwise, we 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.
 	 */
-	boolean_t can_share = arc_can_share(hdr, buf) && !HDR_L2_WRITING(hdr);
+	boolean_t 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 {
@@ -2552,11 +2564,11 @@ 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);
@@ -2587,7 +2599,7 @@ arc_hdr_free_on_write(arc_buf_hdr_t *hdr)
 		arc_space_return(size, ARC_SPACE_DATA);
 	}
 
-	l2arc_free_data_on_write(hdr->b_l1hdr.b_pdata, size, type);
+	l2arc_free_abd_on_write(hdr->b_l1hdr.b_pabd, size, type);
 }
 
 /*
@@ -2601,7 +2613,7 @@ arc_share_buf(arc_buf_hdr_t *hdr, arc_buf_t *buf)
 	arc_state_t *state = hdr->b_l1hdr.b_state;
 
 	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));
 
 	/*
@@ -2610,7 +2622,9 @@ arc_share_buf(arc_buf_hdr_t *hdr, arc_buf_t *buf)
 	 * the refcount whenever an arc_buf_t is shared.
 	 */
 	refcount_transfer_ownership(&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;
 
@@ -2630,7 +2644,7 @@ arc_unshare_buf(arc_buf_hdr_t *hdr, arc_buf_t *buf)
 	arc_state_t *state = hdr->b_l1hdr.b_state;
 
 	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));
 
 	/*
@@ -2639,7 +2653,9 @@ arc_unshare_buf(arc_buf_hdr_t *hdr, arc_buf_t *buf)
 	 */
 	refcount_transfer_ownership(&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;
 
 	/*
@@ -2734,7 +2750,7 @@ 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.
 		 *
@@ -2749,8 +2765,8 @@ 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
@@ -2788,26 +2804,26 @@ 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
@@ -2819,10 +2835,10 @@ 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));
@@ -2859,7 +2875,7 @@ 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);
@@ -2900,7 +2916,7 @@ 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);
@@ -2918,11 +2934,11 @@ 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);
 
 #ifdef ZFS_DEBUG
 		if (hdr->b_l1hdr.b_thawed != NULL) {
@@ -3011,6 +3027,18 @@ 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);
 }
 
@@ -3086,8 +3114,8 @@ arc_hdr_destroy(arc_buf_hdr_t *hdr)
 		}
 #endif
 
-		if (hdr->b_l1hdr.b_pdata != NULL) {
-			arc_hdr_free_pdata(hdr);
+		if (hdr->b_l1hdr.b_pabd != NULL) {
+			arc_hdr_free_pabd(hdr);
 		}
 	}
 
@@ -3155,7 +3183,7 @@ 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 it's L1 piece) until the header is
 		 * done being written to the l2arc.
@@ -3170,7 +3198,7 @@ arc_evict_hdr(arc_buf_hdr_t *hdr, kmutex_t *hash_lock)
 
 		DTRACE_PROBE1(arc__delete, arc_buf_hdr_t *, hdr);
 
-		ASSERT3P(hdr->b_l1hdr.b_pdata, ==, NULL);
+		ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
 		if (HDR_HAS_L2HDR(hdr)) {
 			/*
 			 * This buffer is cached on the 2nd Level ARC;
@@ -3236,9 +3264,9 @@ 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));
@@ -3336,7 +3364,7 @@ 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
@@ -3999,6 +4027,7 @@ arc_kmem_reap_now(void)
 	extern kmem_cache_t	*zio_buf_cache[];
 	extern kmem_cache_t	*zio_data_buf_cache[];
 	extern kmem_cache_t	*range_seg_cache;
+	extern kmem_cache_t	*abd_chunk_cache;
 
 #ifdef _KERNEL
 	if (arc_meta_used >= arc_meta_limit) {
@@ -4026,6 +4055,7 @@ arc_kmem_reap_now(void)
 			kmem_cache_reap_now(zio_data_buf_cache[i]);
 		}
 	}
+	kmem_cache_reap_now(abd_chunk_cache);
 	kmem_cache_reap_now(buf_cache);
 	kmem_cache_reap_now(hdr_full_cache);
 	kmem_cache_reap_now(hdr_l2only_cache);
@@ -4041,13 +4071,13 @@ 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,
@@ -4087,7 +4117,7 @@ arc_reclaim_thread(void)
 		/*
 		 * We call arc_adjust() before (possibly) calling
 		 * arc_kmem_reap_now(), so that we can wake up
-		 * arc_get_data_buf() sooner.
+		 * arc_get_data_impl() sooner.
 		 */
 		evicted = arc_adjust();
 
@@ -4244,18 +4274,45 @@ 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);
 
@@ -4297,11 +4354,8 @@ 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);
 	}
 
@@ -4337,14 +4391,34 @@ 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);
@@ -4361,11 +4435,9 @@ 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);
 	}
 }
@@ -4638,7 +4710,7 @@ 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) ||
@@ -4734,7 +4806,7 @@ 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;
 
@@ -4877,7 +4949,7 @@ top:
 				hdr = arc_hdr_realloc(hdr, hdr_l2only_cache,
 				    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));
@@ -4895,9 +4967,9 @@ 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);
 
 		/*
@@ -5000,7 +5072,7 @@ 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 |
@@ -5039,7 +5111,7 @@ 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)
@@ -5223,16 +5295,17 @@ 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)) {
@@ -5248,7 +5321,7 @@ 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,
@@ -5267,7 +5340,7 @@ 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);
@@ -5345,15 +5418,15 @@ 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));
 
@@ -5375,33 +5448,47 @@ arc_write_ready(zio_t *zio)
 	HDR_SET_PSIZE(hdr, psize);
 	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);
 }
 
@@ -5506,6 +5593,7 @@ 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));
 }
 
@@ -5542,10 +5630,10 @@ arc_write(zio_t *pio, spa_t *spa, uint64_t txg, blkptr_t *bp, arc_buf_t *buf,
 	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.
@@ -5555,15 +5643,16 @@ arc_write(zio_t *pio, spa_t *spa, uint64_t txg, blkptr_t *bp, arc_buf_t *buf,
 		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,
 	    arc_write_physdone, arc_write_done, callback,
@@ -6319,13 +6408,8 @@ l2arc_do_free_on_write()
 
 	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));
 	}
@@ -6475,12 +6559,12 @@ 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	*/
 
@@ -6514,7 +6598,7 @@ 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));
 		}
@@ -6802,7 +6886,7 @@ 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);
 			uint64_t size = arc_hdr_size(hdr);
 
@@ -6817,20 +6901,15 @@ l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz)
 			 * lifetime of the ZIO and be cleaned up afterwards, we
 			 * add it to the l2arc_free_on_write queue.
 			 */
-			void *to_write;
+			abd_t *to_write;
 			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/usr/src/uts/common/fs/zfs/blkptr.c b/usr/src/uts/common/fs/zfs/blkptr.c
index 7e61dc96ff..ff93ff4456 100644
--- a/usr/src/uts/common/fs/zfs/blkptr.c
+++ b/usr/src/uts/common/fs/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/usr/src/uts/common/fs/zfs/dbuf.c b/usr/src/uts/common/fs/zfs/dbuf.c
index e039135aef..85699a7731 100644
--- a/usr/src/uts/common/fs/zfs/dbuf.c
+++ b/usr/src/uts/common/fs/zfs/dbuf.c
@@ -46,6 +46,7 @@
 #include <sys/blkptr.h>
 #include <sys/range_tree.h>
 #include <sys/callb.h>
+#include <sys/abd.h>
 
 uint_t zfs_dbuf_evict_key;
 
@@ -3457,8 +3458,10 @@ dbuf_write_override_done(zio_t *zio)
 		arc_release(dr->dt.dl.dr_data, db);
 	}
 	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. */
@@ -3551,7 +3554,8 @@ 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, &zp,
diff --git a/usr/src/uts/common/fs/zfs/ddt.c b/usr/src/uts/common/fs/zfs/ddt.c
index 9955f89e77..ba3e02cfb5 100644
--- a/usr/src/uts/common/fs/zfs/ddt.c
+++ b/usr/src/uts/common/fs/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>
 
 /*
  * Enable/disable prefetching of dedup-ed blocks which are going to be freed.
@@ -651,9 +652,8 @@ ddt_free(ddt_entry_t *dde)
 	for (int 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_free(dde, sizeof (*dde));
@@ -917,7 +917,7 @@ 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
@@ -954,7 +954,7 @@ 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/usr/src/uts/common/fs/zfs/dmu.c b/usr/src/uts/common/fs/zfs/dmu.c
index 9d41832062..20a41cc98e 100644
--- a/usr/src/uts/common/fs/zfs/dmu.c
+++ b/usr/src/uts/common/fs/zfs/dmu.c
@@ -46,6 +46,7 @@
 #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>
@@ -1632,6 +1633,7 @@ 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));
 }
 
@@ -1657,10 +1659,10 @@ dmu_sync_late_arrival(zio_t *pio, objset_t *os, dmu_sync_cb_t *done, zgd_t *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));
+	    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);
 }
@@ -2193,6 +2195,7 @@ byteswap_uint8_array(void *vbuf, size_t size)
 void
 dmu_init(void)
 {
+	abd_init();
 	zfs_dbgmsg_init();
 	sa_cache_init();
 	xuio_stat_init();
@@ -2216,4 +2219,5 @@ dmu_fini(void)
 	xuio_stat_fini();
 	sa_cache_fini();
 	zfs_dbgmsg_fini();
+	abd_fini();
 }
diff --git a/usr/src/uts/common/fs/zfs/dmu_send.c b/usr/src/uts/common/fs/zfs/dmu_send.c
index e0abf7dbac..ac71c5a11a 100644
--- a/usr/src/uts/common/fs/zfs/dmu_send.c
+++ b/usr/src/uts/common/fs/zfs/dmu_send.c
@@ -132,7 +132,7 @@ 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) {
@@ -145,13 +145,13 @@ 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));
@@ -1742,11 +1742,11 @@ 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));
@@ -2419,9 +2419,9 @@ 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/usr/src/uts/common/fs/zfs/dsl_scan.c b/usr/src/uts/common/fs/zfs/dsl_scan.c
index 7fa7b6f53c..b3fd3c2fba 100644
--- a/usr/src/uts/common/fs/zfs/dsl_scan.c
+++ b/usr/src/uts/common/fs/zfs/dsl_scan.c
@@ -20,8 +20,8 @@
  */
 /*
  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2011, 2015 by Delphix. All rights reserved.
  * Copyright 2016 Gary Mills
+ * Copyright (c) 2011, 2016 by Delphix. All rights reserved.
  */
 
 #include <sys/dsl_scan.h>
@@ -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
@@ -1757,7 +1758,7 @@ 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--;
@@ -1840,7 +1841,6 @@ 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)
@@ -1855,9 +1855,9 @@ 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/usr/src/uts/common/fs/zfs/edonr_zfs.c b/usr/src/uts/common/fs/zfs/edonr_zfs.c
index 93f1221fd5..9a3430d946 100644
--- a/usr/src/uts/common/fs/zfs/edonr_zfs.c
+++ b/usr/src/uts/common/fs/zfs/edonr_zfs.c
@@ -22,19 +22,31 @@
  * 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/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];
@@ -42,7 +54,7 @@ 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));
 }
@@ -51,12 +63,12 @@ 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]);
@@ -64,7 +76,7 @@ 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];
@@ -93,7 +105,7 @@ 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/usr/src/uts/common/fs/zfs/lz4.c b/usr/src/uts/common/fs/zfs/lz4.c
index 3aa1b74ef3..82a08939dc 100644
--- a/usr/src/uts/common/fs/zfs/lz4.c
+++ b/usr/src/uts/common/fs/zfs/lz4.c
@@ -31,6 +31,9 @@
  * - LZ4 homepage : http://fastcompression.blogspot.com/p/lz4.html
  * - LZ4 source repository : http://code.google.com/p/lz4/
  */
+/*
+ * Copyright (c) 2016 by Delphix. All rights reserved.
+ */
 
 #include <sys/zfs_context.h>
 
diff --git a/usr/src/uts/common/fs/zfs/sha256.c b/usr/src/uts/common/fs/zfs/sha256.c
index 81a7f6b1c2..23a97aa3de 100644
--- a/usr/src/uts/common/fs/zfs/sha256.c
+++ b/usr/src/uts/common/fs/zfs/sha256.c
@@ -24,29 +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/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]);
@@ -56,24 +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/usr/src/uts/common/fs/zfs/skein_zfs.c b/usr/src/uts/common/fs/zfs/skein_zfs.c
index 6592340396..340da7adfb 100644
--- a/usr/src/uts/common/fs/zfs/skein_zfs.c
+++ b/usr/src/uts/common/fs/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;
 
@@ -79,10 +89,10 @@ zio_checksum_skein_tmpl_init(const zio_cksum_salt_t *salt)
 
 /*
  * Frees a skein context template previously allocated using
- * zio_checksum_skein_tmpl_init.
+ * abd_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/usr/src/uts/common/fs/zfs/spa.c b/usr/src/uts/common/fs/zfs/spa.c
index b16195da07..3fcce9b113 100644
--- a/usr/src/uts/common/fs/zfs/spa.c
+++ b/usr/src/uts/common/fs/zfs/spa.c
@@ -70,6 +70,7 @@
 #include <sys/dsl_scan.h>
 #include <sys/zfeature.h>
 #include <sys/dsl_destroy.h>
+#include <sys/abd.h>
 
 #ifdef	_KERNEL
 #include <sys/bootprops.h>
@@ -1876,6 +1877,7 @@ 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)
@@ -1883,7 +1885,6 @@ 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--;
@@ -1913,12 +1914,11 @@ 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);
 
 	zio_t *rio = arg;
 	size_t size = BP_GET_PSIZE(bp);
-	void *data = zio_data_buf_alloc(size);
 
 	mutex_enter(&spa->spa_scrub_lock);
 	while (spa->spa_scrub_inflight >= spa_load_verify_maxinflight)
@@ -1926,7 +1926,7 @@ 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/usr/src/uts/common/fs/zfs/sys/abd.h b/usr/src/uts/common/fs/zfs/sys/abd.h
new file mode 100644
index 0000000000..308f021b76
--- /dev/null
+++ b/usr/src/uts/common/fs/zfs/sys/abd.h
@@ -0,0 +1,150 @@
+/*
+ * This file and its contents are supplied under the terms of the
+ * Common Development and Distribution License ("CDDL"), version 1.0.
+ * You may only use this file in accordance with the terms of version
+ * 1.0 of the CDDL.
+ *
+ * A full copy of the text of the CDDL should have accompanied this
+ * source.  A copy of the CDDL is also available via the Internet at
+ * http://www.illumos.org/license/CDDL.
+ */
+
+/*
+ * Copyright (c) 2014 by Chunwei Chen. All rights reserved.
+ * Copyright (c) 2016 by Delphix. All rights reserved.
+ */
+
+#ifndef _ABD_H
+#define	_ABD_H
+
+#include <sys/isa_defs.h>
+#include <sys/int_types.h>
+#include <sys/debug.h>
+#include <sys/refcount.h>
+#ifdef _KERNEL
+#include <sys/uio.h>
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef enum abd_flags {
+	ABD_FLAG_LINEAR	= 1 << 0,	/* is buffer linear (or scattered)? */
+	ABD_FLAG_OWNER	= 1 << 1,	/* does it own its data buffers? */
+	ABD_FLAG_META	= 1 << 2	/* does this represent FS metadata? */
+} abd_flags_t;
+
+typedef struct abd {
+	abd_flags_t	abd_flags;
+	uint_t		abd_size;	/* excludes scattered abd_offset */
+	struct abd	*abd_parent;
+	refcount_t	abd_children;
+	union {
+		struct abd_scatter {
+			uint_t	abd_offset;
+			uint_t	abd_chunk_size;
+			void	*abd_chunks[];
+		} abd_scatter;
+		struct abd_linear {
+			void	*abd_buf;
+		} abd_linear;
+	} abd_u;
+} abd_t;
+
+typedef int abd_iter_func_t(void *, size_t, void *);
+typedef int abd_iter_func2_t(void *, void *, size_t, void *);
+
+extern boolean_t zfs_abd_scatter_enabled;
+
+inline boolean_t
+abd_is_linear(abd_t *abd)
+{
+	return ((abd->abd_flags & ABD_FLAG_LINEAR) != 0);
+}
+
+/*
+ * Allocations and deallocations
+ */
+
+abd_t *abd_alloc(size_t, boolean_t);
+abd_t *abd_alloc_linear(size_t, boolean_t);
+abd_t *abd_alloc_for_io(size_t, boolean_t);
+abd_t *abd_alloc_sametype(abd_t *, size_t);
+void abd_free(abd_t *);
+abd_t *abd_get_offset(abd_t *, size_t);
+abd_t *abd_get_from_buf(void *, size_t);
+void abd_put(abd_t *);
+
+/*
+ * Conversion to and from a normal buffer
+ */
+
+void *abd_to_buf(abd_t *);
+void *abd_borrow_buf(abd_t *, size_t);
+void *abd_borrow_buf_copy(abd_t *, size_t);
+void abd_return_buf(abd_t *, void *, size_t);
+void abd_return_buf_copy(abd_t *, void *, size_t);
+void abd_take_ownership_of_buf(abd_t *, boolean_t);
+void abd_release_ownership_of_buf(abd_t *);
+
+/*
+ * ABD operations
+ */
+
+int abd_iterate_func(abd_t *, size_t, size_t, abd_iter_func_t *, void *);
+int abd_iterate_func2(abd_t *, abd_t *, size_t, size_t, size_t,
+    abd_iter_func2_t *, void *);
+void abd_copy_off(abd_t *, abd_t *, size_t, size_t, size_t);
+void abd_copy_from_buf_off(abd_t *, const void *, size_t, size_t);
+void abd_copy_to_buf_off(void *, abd_t *, size_t, size_t);
+int abd_cmp(abd_t *, abd_t *, size_t);
+int abd_cmp_buf_off(abd_t *, const void *, size_t, size_t);
+void abd_zero_off(abd_t *, size_t, size_t);
+
+/*
+ * Wrappers for calls with offsets of 0
+ */
+
+inline void
+abd_copy(abd_t *dabd, abd_t *sabd, size_t size)
+{
+	abd_copy_off(dabd, sabd, 0, 0, size);
+}
+
+inline void
+abd_copy_from_buf(abd_t *abd, void *buf, size_t size)
+{
+	abd_copy_from_buf_off(abd, buf, 0, size);
+}
+
+inline void
+abd_copy_to_buf(void* buf, abd_t *abd, size_t size)
+{
+	abd_copy_to_buf_off(buf, abd, 0, size);
+}
+
+inline int
+abd_cmp_buf(abd_t *abd, void *buf, size_t size)
+{
+	return (abd_cmp_buf_off(abd, buf, 0, size));
+}
+
+inline void
+abd_zero(abd_t *abd, size_t size)
+{
+	abd_zero_off(abd, 0, size);
+}
+
+/*
+ * Module lifecycle
+ */
+
+void abd_init(void);
+void abd_fini(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif	/* _ABD_H */
diff --git a/usr/src/uts/common/fs/zfs/sys/ddt.h b/usr/src/uts/common/fs/zfs/sys/ddt.h
index 771610677e..15d2a9a7ad 100644
--- a/usr/src/uts/common/fs/zfs/sys/ddt.h
+++ b/usr/src/uts/common/fs/zfs/sys/ddt.h
@@ -20,6 +20,7 @@
  */
 /*
  * Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016 by Delphix. All rights reserved.
  */
 
 #ifndef _SYS_DDT_H
@@ -35,6 +36,8 @@
 extern "C" {
 #endif
 
+struct abd;
+
 /*
  * On-disk DDT formats, in the desired search order (newest version first).
  */
@@ -108,7 +111,7 @@ struct ddt_entry {
 	ddt_key_t	dde_key;
 	ddt_phys_t	dde_phys[DDT_PHYS_TYPES];
 	zio_t		*dde_lead_zio[DDT_PHYS_TYPES];
-	void		*dde_repair_data;
+	struct abd	*dde_repair_abd;
 	enum ddt_type	dde_type;
 	enum ddt_class	dde_class;
 	uint8_t		dde_loading;
diff --git a/usr/src/uts/common/fs/zfs/sys/spa.h b/usr/src/uts/common/fs/zfs/sys/spa.h
index d0bb431866..0caefcd153 100644
--- a/usr/src/uts/common/fs/zfs/sys/spa.h
+++ b/usr/src/uts/common/fs/zfs/sys/spa.h
@@ -419,15 +419,17 @@ _NOTE(CONSTCOND) } while (0)
 
 #define	BP_GET_FILL(bp) (BP_IS_EMBEDDED(bp) ? 1 : (bp)->blk_fill)
 
+#define	BP_IS_METADATA(bp)	\
+	(BP_GET_LEVEL(bp) > 0 || DMU_OT_IS_METADATA(BP_GET_TYPE(bp)))
+
 #define	BP_GET_ASIZE(bp)	\
 	(BP_IS_EMBEDDED(bp) ? 0 : \
 	DVA_GET_ASIZE(&(bp)->blk_dva[0]) + \
 	DVA_GET_ASIZE(&(bp)->blk_dva[1]) + \
 	DVA_GET_ASIZE(&(bp)->blk_dva[2]))
 
-#define	BP_GET_UCSIZE(bp) \
-	((BP_GET_LEVEL(bp) > 0 || DMU_OT_IS_METADATA(BP_GET_TYPE(bp))) ? \
-	BP_GET_PSIZE(bp) : BP_GET_LSIZE(bp))
+#define	BP_GET_UCSIZE(bp)	\
+	(BP_IS_METADATA(bp) ? BP_GET_PSIZE(bp) : BP_GET_LSIZE(bp))
 
 #define	BP_GET_NDVAS(bp)	\
 	(BP_IS_EMBEDDED(bp) ? 0 : \
@@ -597,8 +599,7 @@ _NOTE(CONSTCOND) } while (0)
 }
 
 #define	BP_GET_BUFC_TYPE(bp)						\
-	(((BP_GET_LEVEL(bp) > 0) || (DMU_OT_IS_METADATA(BP_GET_TYPE(bp)))) ? \
-	ARC_BUFC_METADATA : ARC_BUFC_DATA)
+	(BP_IS_METADATA(bp) ? ARC_BUFC_METADATA : ARC_BUFC_DATA)
 
 typedef enum spa_import_type {
 	SPA_IMPORT_EXISTING,
diff --git a/usr/src/uts/common/fs/zfs/sys/vdev_impl.h b/usr/src/uts/common/fs/zfs/sys/vdev_impl.h
index ff14aa80c8..b7f4219117 100644
--- a/usr/src/uts/common/fs/zfs/sys/vdev_impl.h
+++ b/usr/src/uts/common/fs/zfs/sys/vdev_impl.h
@@ -52,6 +52,7 @@ extern "C" {
 typedef struct vdev_queue vdev_queue_t;
 typedef struct vdev_cache vdev_cache_t;
 typedef struct vdev_cache_entry vdev_cache_entry_t;
+struct abd;
 
 extern int zfs_vdev_queue_depth_pct;
 extern uint32_t zfs_vdev_async_write_max_active;
@@ -86,7 +87,7 @@ typedef struct vdev_ops {
  * Virtual device properties
  */
 struct vdev_cache_entry {
-	char		*ve_data;
+	struct abd	*ve_abd;
 	uint64_t	ve_offset;
 	uint64_t	ve_lastused;
 	avl_node_t	ve_offset_node;
diff --git a/usr/src/uts/common/fs/zfs/sys/zio.h b/usr/src/uts/common/fs/zfs/sys/zio.h
index 3dc633f419..d1de03923b 100644
--- a/usr/src/uts/common/fs/zfs/sys/zio.h
+++ b/usr/src/uts/common/fs/zfs/sys/zio.h
@@ -306,6 +306,7 @@ typedef void zio_cksum_free_f(void *cbdata, size_t size);
 
 struct zio_bad_cksum;				/* defined in zio_checksum.h */
 struct dnode_phys;
+struct abd;
 
 struct zio_cksum_report {
 	struct zio_cksum_report *zcr_next;
@@ -338,12 +339,12 @@ typedef struct zio_gang_node {
 } zio_gang_node_t;
 
 typedef zio_t *zio_gang_issue_func_t(zio_t *zio, blkptr_t *bp,
-    zio_gang_node_t *gn, void *data);
+    zio_gang_node_t *gn, struct abd *data, uint64_t offset);
 
-typedef void zio_transform_func_t(zio_t *zio, void *data, uint64_t size);
+typedef void zio_transform_func_t(zio_t *zio, struct abd *data, uint64_t size);
 
 typedef struct zio_transform {
-	void			*zt_orig_data;
+	struct abd		*zt_orig_abd;
 	uint64_t		zt_orig_size;
 	uint64_t		zt_bufsize;
 	zio_transform_func_t	*zt_transform;
@@ -404,8 +405,8 @@ struct zio {
 	blkptr_t	io_bp_orig;
 
 	/* Data represented by this I/O */
-	void		*io_data;
-	void		*io_orig_data;
+	struct abd	*io_abd;
+	struct abd	*io_orig_abd;
 	uint64_t	io_size;
 	uint64_t	io_orig_size;
 	/* io_lsize != io_orig_size iff this is a raw write */
@@ -463,19 +464,19 @@ extern zio_t *zio_null(zio_t *pio, spa_t *spa, vdev_t *vd,
 extern zio_t *zio_root(spa_t *spa,
     zio_done_func_t *done, void *private, enum zio_flag flags);
 
-extern zio_t *zio_read(zio_t *pio, spa_t *spa, const blkptr_t *bp, void *data,
-    uint64_t lsize, zio_done_func_t *done, void *private,
+extern zio_t *zio_read(zio_t *pio, spa_t *spa, const blkptr_t *bp,
+    struct abd *data, uint64_t lsize, zio_done_func_t *done, void *private,
     zio_priority_t priority, enum zio_flag flags, const zbookmark_phys_t *zb);
 
 extern zio_t *zio_write(zio_t *pio, spa_t *spa, uint64_t txg, blkptr_t *bp,
-    void *data, uint64_t size, uint64_t psize, const zio_prop_t *zp,
+    struct abd *data, uint64_t size, 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,
     const zbookmark_phys_t *zb);
 
 extern zio_t *zio_rewrite(zio_t *pio, spa_t *spa, uint64_t txg, blkptr_t *bp,
-    void *data, uint64_t size, zio_done_func_t *done, void *private,
+    struct abd *data, uint64_t size, zio_done_func_t *done, void *private,
     zio_priority_t priority, enum zio_flag flags, zbookmark_phys_t *zb);
 
 extern void zio_write_override(zio_t *zio, blkptr_t *bp, int copies,
@@ -491,12 +492,12 @@ extern zio_t *zio_ioctl(zio_t *pio, spa_t *spa, vdev_t *vd, int cmd,
     zio_done_func_t *done, void *private, enum zio_flag flags);
 
 extern zio_t *zio_read_phys(zio_t *pio, vdev_t *vd, uint64_t offset,
-    uint64_t size, void *data, int checksum,
+    uint64_t size, struct abd *data, int checksum,
     zio_done_func_t *done, void *private, zio_priority_t priority,
     enum zio_flag flags, boolean_t labels);
 
 extern zio_t *zio_write_phys(zio_t *pio, vdev_t *vd, uint64_t offset,
-    uint64_t size, void *data, int checksum,
+    uint64_t size, struct abd *data, int checksum,
     zio_done_func_t *done, void *private, zio_priority_t priority,
     enum zio_flag flags, boolean_t labels);
 
@@ -526,19 +527,19 @@ extern void zio_buf_free(void *buf, size_t size);
 extern void *zio_data_buf_alloc(size_t size);
 extern void zio_data_buf_free(void *buf, size_t size);
 
-extern void zio_push_transform(zio_t *zio, void *data, uint64_t size,
+extern void zio_push_transform(zio_t *zio, struct abd *abd, uint64_t size,
     uint64_t bufsize, zio_transform_func_t *transform);
 extern void zio_pop_transforms(zio_t *zio);
 
 extern void zio_resubmit_stage_async(void *);
 
 extern zio_t *zio_vdev_child_io(zio_t *zio, blkptr_t *bp, vdev_t *vd,
-    uint64_t offset, void *data, uint64_t size, int type,
+    uint64_t offset, struct abd *data, uint64_t size, int type,
     zio_priority_t priority, enum zio_flag flags,
     zio_done_func_t *done, void *private);
 
 extern zio_t *zio_vdev_delegated_io(vdev_t *vd, uint64_t offset,
-    void *data, uint64_t size, int type, zio_priority_t priority,
+    struct abd *data, uint64_t size, int type, zio_priority_t priority,
     enum zio_flag flags, zio_done_func_t *done, void *private);
 
 extern void zio_vdev_io_bypass(zio_t *zio);
diff --git a/usr/src/uts/common/fs/zfs/sys/zio_checksum.h b/usr/src/uts/common/fs/zfs/sys/zio_checksum.h
index 2f7579fd73..3eda057eae 100644
--- a/usr/src/uts/common/fs/zfs/sys/zio_checksum.h
+++ b/usr/src/uts/common/fs/zfs/sys/zio_checksum.h
@@ -20,7 +20,7 @@
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2014, 2015 by Delphix. All rights reserved.
+ * Copyright (c) 2014, 2016 by Delphix. All rights reserved.
  * Copyright Saso Kiselkov 2013, All rights reserved.
  */
 
@@ -34,10 +34,12 @@
 extern "C" {
 #endif
 
+struct abd;
+
 /*
  * Signature for checksum functions.
  */
-typedef void zio_checksum_t(const void *data, uint64_t size,
+typedef void zio_checksum_t(struct abd *, uint64_t size,
     const void *ctx_template, zio_cksum_t *zcp);
 typedef void *zio_checksum_tmpl_init_t(const zio_cksum_salt_t *salt);
 typedef void zio_checksum_tmpl_free_t(void *ctx_template);
@@ -81,28 +83,28 @@ extern zio_checksum_info_t zio_checksum_table[ZIO_CHECKSUM_FUNCTIONS];
 /*
  * Checksum routines.
  */
-extern zio_checksum_t zio_checksum_SHA256;
-extern zio_checksum_t zio_checksum_SHA512_native;
-extern zio_checksum_t zio_checksum_SHA512_byteswap;
+extern zio_checksum_t abd_checksum_SHA256;
+extern zio_checksum_t abd_checksum_SHA512_native;
+extern zio_checksum_t abd_checksum_SHA512_byteswap;
 
 /* Skein */
-extern zio_checksum_t zio_checksum_skein_native;
-extern zio_checksum_t zio_checksum_skein_byteswap;
-extern zio_checksum_tmpl_init_t zio_checksum_skein_tmpl_init;
-extern zio_checksum_tmpl_free_t zio_checksum_skein_tmpl_free;
+extern zio_checksum_t abd_checksum_skein_native;
+extern zio_checksum_t abd_checksum_skein_byteswap;
+extern zio_checksum_tmpl_init_t abd_checksum_skein_tmpl_init;
+extern zio_checksum_tmpl_free_t abd_checksum_skein_tmpl_free;
 
 /* Edon-R */
-extern zio_checksum_t zio_checksum_edonr_native;
-extern zio_checksum_t zio_checksum_edonr_byteswap;
-extern zio_checksum_tmpl_init_t zio_checksum_edonr_tmpl_init;
-extern zio_checksum_tmpl_free_t zio_checksum_edonr_tmpl_free;
+extern zio_checksum_t abd_checksum_edonr_native;
+extern zio_checksum_t abd_checksum_edonr_byteswap;
+extern zio_checksum_tmpl_init_t abd_checksum_edonr_tmpl_init;
+extern zio_checksum_tmpl_free_t abd_checksum_edonr_tmpl_free;
 
 extern int zio_checksum_equal(spa_t *, blkptr_t *, enum zio_checksum,
     void *, uint64_t, uint64_t, zio_bad_cksum_t *);
-extern void zio_checksum_compute(zio_t *zio, enum zio_checksum checksum,
-    void *data, uint64_t size);
+extern void zio_checksum_compute(zio_t *, enum zio_checksum,
+    struct abd *, uint64_t);
 extern int zio_checksum_error_impl(spa_t *, blkptr_t *, enum zio_checksum,
-    void *, uint64_t, uint64_t, zio_bad_cksum_t *);
+    struct abd *, uint64_t, uint64_t, zio_bad_cksum_t *);
 extern int zio_checksum_error(zio_t *zio, zio_bad_cksum_t *out);
 extern enum zio_checksum spa_dedup_checksum(spa_t *spa);
 extern void zio_checksum_templates_free(spa_t *spa);
diff --git a/usr/src/uts/common/fs/zfs/sys/zio_compress.h b/usr/src/uts/common/fs/zfs/sys/zio_compress.h
index 0c1783b140..bcffa699b5 100644
--- a/usr/src/uts/common/fs/zfs/sys/zio_compress.h
+++ b/usr/src/uts/common/fs/zfs/sys/zio_compress.h
@@ -25,12 +25,14 @@
  */
 /*
  * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
- * Copyright (c) 2015 by Delphix. All rights reserved.
+ * Copyright (c) 2015, 2016 by Delphix. All rights reserved.
  */
 
 #ifndef _SYS_ZIO_COMPRESS_H
 #define	_SYS_ZIO_COMPRESS_H
 
+#include <sys/abd.h>
+
 #ifdef	__cplusplus
 extern "C" {
 #endif
@@ -61,15 +63,22 @@ typedef size_t zio_compress_func_t(void *src, void *dst,
 /* Common signature for all zio decompress functions. */
 typedef int zio_decompress_func_t(void *src, void *dst,
     size_t s_len, size_t d_len, int);
+/*
+ * Common signature for all zio decompress functions using an ABD as input.
+ * This is helpful if you have both compressed ARC and scatter ABDs enabled,
+ * but is not a requirement for all compression algorithms.
+ */
+typedef int zio_decompress_abd_func_t(abd_t *src, void *dst,
+    size_t s_len, size_t d_len, int);
 
 /*
  * Information about each compression function.
  */
 typedef struct zio_compress_info {
-	zio_compress_func_t	*ci_compress;	/* compression function */
-	zio_decompress_func_t	*ci_decompress;	/* decompression function */
-	int			ci_level;	/* level parameter */
-	char			*ci_name;	/* algorithm name */
+	char				*ci_name;
+	int				ci_level;
+	zio_compress_func_t		*ci_compress;
+	zio_decompress_func_t		*ci_decompress;
 } zio_compress_info_t;
 
 extern zio_compress_info_t zio_compress_table[ZIO_COMPRESS_FUNCTIONS];
@@ -97,9 +106,11 @@ extern int lz4_decompress(void *src, void *dst, size_t s_len, size_t d_len,
 /*
  * Compress and decompress data if necessary.
  */
-extern size_t zio_compress_data(enum zio_compress c, void *src, void *dst,
+extern size_t zio_compress_data(enum zio_compress c, abd_t *src, void *dst,
     size_t s_len);
-extern int zio_decompress_data(enum zio_compress c, void *src, void *dst,
+extern int zio_decompress_data(enum zio_compress c, abd_t *src, void *dst,
+    size_t s_len, size_t d_len);
+extern int zio_decompress_data_buf(enum zio_compress c, void *src, void *dst,
     size_t s_len, size_t d_len);
 
 #ifdef	__cplusplus
diff --git a/usr/src/uts/common/fs/zfs/vdev.c b/usr/src/uts/common/fs/zfs/vdev.c
index c0905abb46..890254ecb8 100644
--- a/usr/src/uts/common/fs/zfs/vdev.c
+++ b/usr/src/uts/common/fs/zfs/vdev.c
@@ -45,6 +45,7 @@
 #include <sys/arc.h>
 #include <sys/zil.h>
 #include <sys/dsl_scan.h>
+#include <sys/abd.h>
 
 /*
  * Virtual device management.
@@ -961,16 +962,16 @@ 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;
 
@@ -1086,8 +1087,8 @@ vdev_probe(vdev_t *vd, zio_t *zio)
 	for (int 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/usr/src/uts/common/fs/zfs/vdev_cache.c b/usr/src/uts/common/fs/zfs/vdev_cache.c
index a6d6cfa61b..9b4755321d 100644
--- a/usr/src/uts/common/fs/zfs/vdev_cache.c
+++ b/usr/src/uts/common/fs/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, 2017 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.
@@ -141,12 +142,12 @@ 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));
 }
 
@@ -176,14 +177,14 @@ 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);
@@ -197,7 +198,7 @@ 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);
@@ -206,7 +207,7 @@ 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);
 }
 
 /*
@@ -220,16 +221,16 @@ vdev_cache_fill(zio_t *fio)
 	vdev_cache_entry_t *ve = fio->io_private;
 	zio_t *pio;
 
-	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;
 
@@ -260,7 +261,7 @@ vdev_cache_read(zio_t *zio)
 	uint64_t cache_phase = P2PHASE(zio->io_offset, VCBS);
 	zio_t *fio;
 
-	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);
@@ -274,7 +275,7 @@ 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);
 
@@ -311,7 +312,7 @@ 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;
@@ -339,7 +340,7 @@ 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);
 
@@ -356,8 +357,9 @@ 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 - ve->ve_offset, start - io_start,
+			    end - start);
 		}
 		ve = AVL_NEXT(&vc->vc_offset_tree, ve);
 	}
diff --git a/usr/src/uts/common/fs/zfs/vdev_disk.c b/usr/src/uts/common/fs/zfs/vdev_disk.c
index 24dcb890e2..24083abbbc 100644
--- a/usr/src/uts/common/fs/zfs/vdev_disk.c
+++ b/usr/src/uts/common/fs/zfs/vdev_disk.c
@@ -30,6 +30,7 @@
 #include <sys/refcount.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>
@@ -658,6 +659,12 @@ vdev_disk_io_intr(buf_t *bp)
 	if (zio->io_error == 0 && bp->b_resid != 0)
 		zio->io_error = SET_ERROR(EIO);
 
+	if (zio->io_type == ZIO_TYPE_READ) {
+		abd_return_buf_copy(zio->io_abd, bp->b_un.b_addr, zio->io_size);
+	} else {
+		abd_return_buf(zio->io_abd, bp->b_un.b_addr, zio->io_size);
+	}
+
 	kmem_free(vb, sizeof (vdev_buf_t));
 
 	zio_delay_interrupt(zio);
@@ -769,7 +776,15 @@ vdev_disk_io_start(zio_t *zio)
 	if (!(zio->io_flags & (ZIO_FLAG_IO_RETRY | ZIO_FLAG_TRYHARD)))
 		bp->b_flags |= B_FAILFAST;
 	bp->b_bcount = zio->io_size;
-	bp->b_un.b_addr = zio->io_data;
+
+	if (zio->io_type == ZIO_TYPE_READ) {
+		bp->b_un.b_addr =
+		    abd_borrow_buf(zio->io_abd, zio->io_size);
+	} else {
+		bp->b_un.b_addr =
+		    abd_borrow_buf_copy(zio->io_abd, zio->io_size);
+	}
+
 	bp->b_lblkno = lbtodb(zio->io_offset);
 	bp->b_bufsize = zio->io_size;
 	bp->b_iodone = (int (*)())vdev_disk_io_intr;
diff --git a/usr/src/uts/common/fs/zfs/vdev_file.c b/usr/src/uts/common/fs/zfs/vdev_file.c
index 633621b0dd..147e693967 100644
--- a/usr/src/uts/common/fs/zfs/vdev_file.c
+++ b/usr/src/uts/common/fs/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.
@@ -157,6 +158,12 @@ vdev_file_io_intr(buf_t *bp)
 	if (zio->io_error == 0 && bp->b_resid != 0)
 		zio->io_error = SET_ERROR(ENOSPC);
 
+	if (zio->io_type == ZIO_TYPE_READ) {
+		abd_return_buf_copy(zio->io_abd, bp->b_un.b_addr, zio->io_size);
+	} else {
+		abd_return_buf(zio->io_abd, bp->b_un.b_addr, zio->io_size);
+	}
+
 	kmem_free(vb, sizeof (vdev_buf_t));
 	zio_delay_interrupt(zio);
 }
@@ -222,7 +229,15 @@ vdev_file_io_start(zio_t *zio)
 	bioinit(bp);
 	bp->b_flags = (zio->io_type == ZIO_TYPE_READ ? B_READ : B_WRITE);
 	bp->b_bcount = zio->io_size;
-	bp->b_un.b_addr = zio->io_data;
+
+	if (zio->io_type == ZIO_TYPE_READ) {
+		bp->b_un.b_addr =
+		    abd_borrow_buf(zio->io_abd, zio->io_size);
+	} else {
+		bp->b_un.b_addr =
+		    abd_borrow_buf_copy(zio->io_abd, zio->io_size);
+	}
+
 	bp->b_lblkno = lbtodb(zio->io_offset);
 	bp->b_bufsize = zio->io_size;
 	bp->b_private = vf->vf_vnode;
diff --git a/usr/src/uts/common/fs/zfs/vdev_label.c b/usr/src/uts/common/fs/zfs/vdev_label.c
index 866046315c..b76589f0f6 100644
--- a/usr/src/uts/common/fs/zfs/vdev_label.c
+++ b/usr/src/uts/common/fs/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 ||
@@ -444,6 +445,7 @@ 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;
@@ -455,7 +457,8 @@ 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 (int l = 0; l < VDEV_LABELS; l++) {
@@ -463,7 +466,7 @@ 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);
 
@@ -502,7 +505,7 @@ retry:
 		goto retry;
 	}
 
-	zio_buf_free(vp, sizeof (vdev_phys_t));
+	abd_free(vp_abd);
 
 	return (config);
 }
@@ -636,8 +639,10 @@ 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;
@@ -719,8 +724,9 @@ 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.
@@ -780,7 +786,7 @@ 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);
 	}
@@ -788,14 +794,15 @@ 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.
@@ -805,7 +812,7 @@ retry:
 
 	for (int 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);
 
@@ -818,7 +825,7 @@ 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);
 	}
@@ -831,9 +838,9 @@ 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
@@ -897,7 +904,7 @@ 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));
@@ -918,7 +925,7 @@ 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
@@ -932,8 +939,8 @@ vdev_uberblock_load_impl(zio_t *zio, vdev_t *vd, int flags,
 		for (int l = 0; l < VDEV_LABELS; l++) {
 			for (int 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);
 			}
@@ -1000,9 +1007,6 @@ 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;
-	int n;
-
 	for (int c = 0; c < vd->vdev_children; c++)
 		vdev_uberblock_sync(zio, ub, vd->vdev_child[c], flags);
 
@@ -1012,19 +1016,20 @@ vdev_uberblock_sync(zio_t *zio, uberblock_t *ub, vdev_t *vd, int flags)
 	if (!vdev_writeable(vd))
 		return;
 
-	n = ub->ub_txg & (VDEV_UBERBLOCK_COUNT(vd) - 1);
+	int 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 */
+	abd_t *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 (int 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[] */
@@ -1100,6 +1105,7 @@ 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;
 
@@ -1117,15 +1123,16 @@ 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) == 0) {
 		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,
@@ -1133,7 +1140,7 @@ 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/usr/src/uts/common/fs/zfs/vdev_mirror.c b/usr/src/uts/common/fs/zfs/vdev_mirror.c
index b038ef6f67..a57bd6c73b 100644
--- a/usr/src/uts/common/fs/zfs/vdev_mirror.c
+++ b/usr/src/uts/common/fs/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>
 
 /*
@@ -196,13 +197,12 @@ 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;
@@ -282,7 +282,8 @@ 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));
 			}
@@ -307,7 +308,7 @@ 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++;
@@ -392,7 +393,7 @@ 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;
@@ -433,7 +434,7 @@ 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/usr/src/uts/common/fs/zfs/vdev_queue.c b/usr/src/uts/common/fs/zfs/vdev_queue.c
index ac586c879f..b4a84914d5 100644
--- a/usr/src/uts/common/fs/zfs/vdev_queue.c
+++ b/usr/src/uts/common/fs/zfs/vdev_queue.c
@@ -35,6 +35,7 @@
 #include <sys/avl.h>
 #include <sys/dsl_pool.h>
 #include <sys/metaslab_impl.h>
+#include <sys/abd.h>
 
 /*
  * ZFS I/O Scheduler
@@ -371,12 +372,12 @@ 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);
 }
 
 static int
@@ -611,8 +612,8 @@ vdev_queue_aggregate(vdev_queue_t *vq, zio_t *zio)
 	ASSERT3U(size, <=, zfs_vdev_aggregation_limit);
 
 	aio = zio_vdev_delegated_io(first->io_vd, first->io_offset,
-	    zio_buf_alloc(size), size, first->io_type, zio->io_priority,
-	    flags | ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_QUEUE,
+	    abd_alloc_for_io(size, B_TRUE), 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;
 
@@ -624,12 +625,11 @@ 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/usr/src/uts/common/fs/zfs/vdev_raidz.c b/usr/src/uts/common/fs/zfs/vdev_raidz.c
index ff06896e8d..109534f529 100644
--- a/usr/src/uts/common/fs/zfs/vdev_raidz.c
+++ b/usr/src/uts/common/fs/zfs/vdev_raidz.c
@@ -21,7 +21,7 @@
 
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2012, 2014 by Delphix. All rights reserved.
+ * Copyright (c) 2012, 2017 by Delphix. All rights reserved.
  * Copyright (c) 2013, Joyent, Inc. All rights reserved.
  * Copyright (c) 2014 Integros [integros.com]
  */
@@ -34,6 +34,7 @@
 #include <sys/vdev_raidz.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>
 
@@ -108,7 +109,7 @@ typedef struct raidz_col {
 	uint64_t rc_devidx;		/* child device index for I/O */
 	uint64_t rc_offset;		/* device offset */
 	uint64_t rc_size;		/* I/O size */
-	void *rc_data;			/* I/O data */
+	abd_t *rc_abd;			/* I/O data */
 	void *rc_gdata;			/* used to store the "good" version */
 	int rc_error;			/* I/O error for this device */
 	uint8_t rc_tried;		/* Did we attempt this I/O column? */
@@ -125,7 +126,7 @@ typedef struct raidz_map {
 	uint64_t rm_firstdatacol;	/* First data column/parity count */
 	uint64_t rm_nskip;		/* Skipped sectors for padding */
 	uint64_t rm_skipstart;		/* Column index of padding start */
-	void *rm_datacopy;		/* rm_asize-buffer of copied data */
+	abd_t *rm_abd_copy;		/* rm_asize-buffer of copied data */
 	uintptr_t rm_reports;		/* # of referencing checksum reports */
 	uint8_t	rm_freed;		/* map no longer has referencing ZIO */
 	uint8_t	rm_ecksuminjected;	/* checksum error was injected */
@@ -265,7 +266,7 @@ 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,
@@ -273,11 +274,13 @@ 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]));
 }
@@ -314,7 +317,7 @@ 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);
@@ -328,8 +331,9 @@ 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
@@ -337,15 +341,20 @@ 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;
 			}
 
@@ -355,13 +364,17 @@ 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;
 			}
 		}
 
@@ -375,8 +388,10 @@ 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);
 }
 
 /*
@@ -389,7 +404,7 @@ 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;
@@ -403,7 +418,7 @@ 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;
 
 	/*
@@ -419,17 +434,20 @@ 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 = {
@@ -442,7 +460,7 @@ static const zio_vsd_ops_t vdev_raidz_vsd_ops = {
  * the number of children in the target vdev.
  */
 static raidz_map_t *
-vdev_raidz_map_alloc(caddr_t data, uint64_t size, uint64_t offset,
+vdev_raidz_map_alloc(abd_t *abd, uint64_t size, uint64_t offset,
     uint64_t unit_shift, uint64_t dcols, uint64_t nparity)
 {
 	raidz_map_t *rm;
@@ -455,6 +473,7 @@ vdev_raidz_map_alloc(caddr_t data, uint64_t size, uint64_t offset,
 	/* 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
@@ -499,7 +518,7 @@ vdev_raidz_map_alloc(caddr_t data, uint64_t size, uint64_t offset,
 	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;
@@ -515,7 +534,7 @@ vdev_raidz_map_alloc(caddr_t data, uint64_t size, uint64_t offset,
 		}
 		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;
@@ -538,13 +557,16 @@ vdev_raidz_map_alloc(caddr_t data, uint64_t size, uint64_t offset,
 	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 = data;
+	rm->rm_col[c].rc_abd = abd_get_offset(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(abd, off);
+		off += rm->rm_col[c].rc_size;
+	}
 
 	/*
 	 * If all data stored spans all columns, there's a danger that parity
@@ -584,29 +606,84 @@ vdev_raidz_map_alloc(caddr_t data, uint64_t size, uint64_t offset,
 	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);
 		}
 	}
 }
@@ -614,50 +691,42 @@ 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);
 			}
 		}
 	}
@@ -666,59 +735,48 @@ 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);
 			}
 		}
 	}
@@ -746,40 +804,153 @@ 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]);
+
+	for (int 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]);
+
+	for (int 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]);
+
+	for (int 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]);
+
+	for (int i = 0; i < cnt; i++, dst++, rq->q++) {
+		*dst ^= *rq->q;
+
+		int j;
+		uint8_t *b;
+		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;
+
+	for (int 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;
+
+	for (int 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(dst, 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);
@@ -788,57 +959,43 @@ 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;
 
 	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);
 
-	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);
-		}
-	}
+	struct reconst_q_struct rq = { abd_to_buf(src), 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);
 }
@@ -846,11 +1003,12 @@ 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;
 
 	ASSERT(ntgts == 2);
 	ASSERT(x < y);
@@ -866,15 +1024,15 @@ 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;
 
@@ -883,12 +1041,12 @@ 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:
@@ -912,24 +1070,21 @@ 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);
+	struct reconst_pq_struct rpq = { p, q, pxy, qxy, aexp, bexp };
+	(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);
 
-		if (i < ysize)
-			*yd = *p ^ *pxy ^ *xd;
-	}
-
-	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));
 }
@@ -1244,7 +1399,7 @@ 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;
@@ -1252,7 +1407,7 @@ 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;
 		}
 
@@ -1300,8 +1455,25 @@ 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;
 
@@ -1388,6 +1560,20 @@ 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);
 }
 
@@ -1619,7 +1805,9 @@ vdev_raidz_physio(vdev_t *vd, caddr_t data, size_t size,
 	 * treat the on-disk format as if the only blocks are the complete 128
 	 * KB size.
 	 */
-	rm = vdev_raidz_map_alloc(data - (offset - origoffset),
+	abd_t *abd = abd_get_from_buf(data - (offset - origoffset),
+	    SPA_OLD_MAXBLOCKSIZE);
+	rm = vdev_raidz_map_alloc(abd,
 	    SPA_OLD_MAXBLOCKSIZE, origoffset, tvd->vdev_ashift,
 	    vd->vdev_children, vd->vdev_nparity);
 
@@ -1658,13 +1846,14 @@ vdev_raidz_physio(vdev_t *vd, caddr_t data, size_t size,
 		 * example of why this calculation is needed.
 		 */
 		if ((err = vdev_disk_physio(cvd,
-		    ((char *)rc->rc_data) + colskip, colsize,
+		    ((char *)abd_to_buf(rc->rc_abd)) + colskip, colsize,
 		    VDEV_LABEL_OFFSET(rc->rc_offset) + colskip,
 		    flags, isdump)) != 0)
 			break;
 	}
 
 	vdev_raidz_map_free(rm);
+	abd_put(abd);
 #endif	/* KERNEL */
 
 	return (err);
@@ -1722,7 +1911,7 @@ vdev_raidz_io_start(zio_t *zio)
 	raidz_col_t *rc;
 	int c, i;
 
-	rm = vdev_raidz_map_alloc(zio->io_data, zio->io_size, zio->io_offset,
+	rm = vdev_raidz_map_alloc(zio->io_abd, zio->io_size, zio->io_offset,
 	    tvd->vdev_ashift, vd->vdev_children,
 	    vd->vdev_nparity);
 
@@ -1738,7 +1927,7 @@ 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));
 		}
@@ -1795,7 +1984,7 @@ 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));
 		}
@@ -1811,6 +2000,7 @@ 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)) {
@@ -1824,9 +2014,11 @@ 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);
 	}
 }
 
@@ -1872,7 +2064,7 @@ 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);
@@ -1881,7 +2073,7 @@ 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 (abd_cmp_buf(rc->rc_abd, orig[c], rc->rc_size) != 0) {
 			raidz_checksum_error(zio, rc, orig[c]);
 			rc->rc_error = SET_ERROR(ECKSUM);
 			ret++;
@@ -1989,7 +2181,8 @@ 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);
 			}
 
 			/*
@@ -2020,7 +2213,8 @@ 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 {
@@ -2261,7 +2455,7 @@ 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);
@@ -2341,7 +2535,7 @@ 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/usr/src/uts/common/fs/zfs/zil.c b/usr/src/uts/common/fs/zfs/zil.c
index 72e4e0e04b..6229728d2a 100644
--- a/usr/src/uts/common/fs/zfs/zil.c
+++ b/usr/src/uts/common/fs/zfs/zil.c
@@ -39,6 +39,7 @@
 #include <sys/vdev_impl.h>
 #include <sys/dmu_tx.h>
 #include <sys/dsl_pool.h>
+#include <sys/abd.h>
 
 /*
  * The zfs intent log (ZIL) saves transaction records of system calls
@@ -867,6 +868,7 @@ 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_buf = NULL;
@@ -898,8 +900,10 @@ zil_lwb_write_init(zilog_t *zilog, lwb_t *lwb)
 		    ZIO_FLAG_CANFAIL);
 	}
 	if (lwb->lwb_zio == NULL) {
+		abd_t *lwb_abd = abd_get_from_buf(lwb->lwb_buf,
+		    BP_GET_LSIZE(&lwb->lwb_blk));
 		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, &zb);
 	}
diff --git a/usr/src/uts/common/fs/zfs/zio.c b/usr/src/uts/common/fs/zfs/zio.c
index 92e28d821d..c7d2e0536e 100644
--- a/usr/src/uts/common/fs/zfs/zio.c
+++ b/usr/src/uts/common/fs/zfs/zio.c
@@ -41,6 +41,7 @@
 #include <sys/blkptr.h>
 #include <sys/zfeature.h>
 #include <sys/metaslab_impl.h>
+#include <sys/abd.h>
 
 /*
  * ==========================================================================
@@ -272,12 +273,18 @@ 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;
@@ -285,7 +292,7 @@ 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;
 }
 
@@ -297,12 +304,12 @@ 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;
 
@@ -316,21 +323,26 @@ 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);
+	}
 }
 
 /*
@@ -528,7 +540,7 @@ zio_bookmark_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, enum zio_stage pipeline)
@@ -587,7 +599,7 @@ 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;
@@ -726,7 +738,7 @@ 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;
@@ -744,7 +756,7 @@ 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,
@@ -785,7 +797,7 @@ 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)
 {
@@ -938,7 +950,7 @@ 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;
@@ -959,7 +971,7 @@ 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;
@@ -982,8 +994,9 @@ 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);
 	}
 
@@ -995,7 +1008,7 @@ 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;
@@ -1060,7 +1073,7 @@ 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)
 {
@@ -1121,14 +1134,17 @@ 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) {
 		zio->io_pipeline = ZIO_INTERLOCK_PIPELINE;
-		decode_embedded_bp_compressed(bp, zio->io_data);
+
+		int psize = BPE_GET_PSIZE(bp);
+		void *data = abd_borrow_buf(zio->io_abd, psize);
+		decode_embedded_bp_compressed(bp, data);
+		abd_return_buf_copy(zio->io_abd, data, psize);
 	} else {
 		ASSERT(!BP_IS_EMBEDDED(bp));
 	}
@@ -1268,7 +1284,7 @@ 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);
@@ -1303,9 +1319,11 @@ 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);
 			}
 		}
@@ -1825,26 +1843,38 @@ 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
@@ -1855,8 +1885,12 @@ 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,
@@ -1866,7 +1900,8 @@ 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);
 	}
 
@@ -1874,16 +1909,18 @@ 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)));
@@ -1945,13 +1982,14 @@ 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
@@ -1967,13 +2005,16 @@ 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 (int g = 0; g < SPA_GBH_NBLKPTRS; g++) {
 		blkptr_t *gbp = &gn->gn_gbh->zg_blkptr[g];
 		if (!BP_IS_GANG(gbp))
@@ -1983,7 +2024,8 @@ 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;
@@ -1996,7 +2038,7 @@ 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);
@@ -2005,13 +2047,14 @@ 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);
@@ -2044,7 +2087,8 @@ 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);
 
@@ -2083,6 +2127,12 @@ 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)
 {
@@ -2093,6 +2143,7 @@ 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;
@@ -2153,12 +2204,14 @@ 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.
@@ -2178,9 +2231,9 @@ zio_write_gang_block(zio_t *pio)
 		zp.zp_nopwrite = B_FALSE;
 
 		zio_t *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) {
@@ -2293,10 +2346,11 @@ 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);
 }
 
@@ -2328,16 +2382,16 @@ 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);
@@ -2367,8 +2421,9 @@ 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);
@@ -2400,7 +2455,7 @@ zio_ddt_collision(zio_t *zio, ddt_t *ddt, ddt_entry_t *dde)
 
 		if (lio != NULL) {
 			return (lio->io_orig_size != zio->io_orig_size ||
-			    bcmp(zio->io_orig_data, lio->io_orig_data,
+			    abd_cmp(zio->io_orig_abd, lio->io_orig_abd,
 			    zio->io_orig_size) != 0);
 		}
 	}
@@ -2421,17 +2476,17 @@ zio_ddt_collision(zio_t *zio, ddt_t *ddt, ddt_entry_t *dde)
 
 			/*
 			 * Intuitively, it would make more sense to compare
-			 * io_data than io_orig_data in the raw case since you
+			 * io_abd than io_orig_abd in the raw case since you
 			 * don't want to look at any transformations that have
 			 * happened to the data. However, for raw I/Os the
-			 * data will actually be the same in io_data and
-			 * io_orig_data, so all we have to do is issue this as
+			 * data will actually be the same in io_abd and
+			 * io_orig_abd, so all we have to do is issue this as
 			 * a raw ARC read.
 			 */
 			if (do_raw) {
 				zio_flags |= ZIO_FLAG_RAW;
 				ASSERT3U(zio->io_size, ==, zio->io_orig_size);
-				ASSERT0(bcmp(zio->io_data, zio->io_orig_data,
+				ASSERT0(abd_cmp(zio->io_abd, zio->io_orig_abd,
 				    zio->io_size));
 				ASSERT3P(zio->io_transform_stack, ==, NULL);
 			}
@@ -2442,7 +2497,7 @@ zio_ddt_collision(zio_t *zio, ddt_t *ddt, ddt_entry_t *dde)
 
 			if (error == 0) {
 				if (arc_buf_size(abuf) != zio->io_orig_size ||
-				    bcmp(abuf->b_data, zio->io_orig_data,
+				    abd_cmp_buf(zio->io_orig_abd, abuf->b_data,
 				    zio->io_orig_size) != 0)
 					error = SET_ERROR(EEXIST);
 				arc_buf_destroy(abuf, &abuf);
@@ -2608,12 +2663,12 @@ 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;
 	}
 
@@ -2630,13 +2685,13 @@ 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;
 	}
 
@@ -2976,11 +3031,11 @@ 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);
 	}
@@ -3106,7 +3161,7 @@ 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;
@@ -3250,7 +3305,7 @@ 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);
 }
@@ -3389,7 +3444,7 @@ 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;
 		}
 	}
@@ -3544,21 +3599,28 @@ zio_done(zio_t *zio)
 			zio_cksum_report_t *zcr = zio->io_cksum_report;
 			uint64_t align = zcr->zcr_align;
 			uint64_t asize = P2ROUNDUP(psize, align);
-			char *abuf = zio->io_data;
+			char *abuf = NULL;
+			abd_t *adata = zio->io_abd;
 
 			if (asize != psize) {
-				abuf = zio_buf_alloc(asize);
-				bcopy(zio->io_data, abuf, psize);
-				bzero(abuf + psize, 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 (adata != NULL)
+				abd_return_buf(adata, abuf, asize);
+
 			if (asize != psize)
-				zio_buf_free(abuf, asize);
+				abd_free(adata);
 		}
 	}
 
diff --git a/usr/src/uts/common/fs/zfs/zio_checksum.c b/usr/src/uts/common/fs/zfs/zio_checksum.c
index 2bd9001456..e1c98b0b99 100644
--- a/usr/src/uts/common/fs/zfs/zio_checksum.c
+++ b/usr/src/uts/common/fs/zfs/zio_checksum.c
@@ -31,6 +31,7 @@
 #include <sys/zio.h>
 #include <sys/zio_checksum.h>
 #include <sys/zil.h>
+#include <sys/abd.h>
 #include <zfs_fletcher.h>
 
 /*
@@ -93,45 +94,85 @@
 
 /*ARGSUSED*/
 static void
-zio_checksum_off(const void *buf, uint64_t size,
+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];
 	zio_cksum_t actual_cksum, expected_cksum;
@@ -308,25 +350,31 @@ 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;
+		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 +389,15 @@ zio_checksum_error_impl(spa_t *spa, blkptr_t *bp, enum zio_checksum checksum,
 		if (byteswap)
 			byteswap_uint64_array(&verifier, sizeof (zio_cksum_t));
 
+		size_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 +406,7 @@ 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 +435,7 @@ 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/usr/src/uts/common/fs/zfs/zio_compress.c b/usr/src/uts/common/fs/zfs/zio_compress.c
index 4e2d645572..8d0a33de69 100644
--- a/usr/src/uts/common/fs/zfs/zio_compress.c
+++ b/usr/src/uts/common/fs/zfs/zio_compress.c
@@ -25,10 +25,7 @@
  */
 /*
  * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
- */
-
-/*
- * Copyright (c) 2013 by Delphix. All rights reserved.
+ * Copyright (c) 2013, 2016 by Delphix. All rights reserved.
  */
 
 #include <sys/zfs_context.h>
@@ -41,24 +38,23 @@
 /*
  * 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,		lz4_decompress,		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,	lz4_decompress}
 };
 
 enum zio_compress
@@ -85,10 +81,21 @@ 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);
+	for (uint64_t *word = (uint64_t *)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];
 
@@ -99,12 +106,7 @@ 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 +114,11 @@ 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 */
+	void *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 +128,23 @@ 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);
+}