Move the world out of /zfs/ and seperate out module build tree

1 files changed, 1227 insertions, 0 deletions

diff --git a/module/zfs/dmu.c b/module/zfs/dmu.c
new file mode 100644
index 000000000..b6205bd50
--- /dev/null
+++ b/module/zfs/dmu.c
@@ -0,0 +1,1227 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+#include <sys/dmu.h>
+#include <sys/dmu_impl.h>
+#include <sys/dmu_tx.h>
+#include <sys/dbuf.h>
+#include <sys/dnode.h>
+#include <sys/zfs_context.h>
+#include <sys/dmu_objset.h>
+#include <sys/dmu_traverse.h>
+#include <sys/dsl_dataset.h>
+#include <sys/dsl_dir.h>
+#include <sys/dsl_pool.h>
+#include <sys/dsl_synctask.h>
+#include <sys/dsl_prop.h>
+#include <sys/dmu_zfetch.h>
+#include <sys/zfs_ioctl.h>
+#include <sys/zap.h>
+#include <sys/zio_checksum.h>
+#ifdef _KERNEL
+#include <sys/vmsystm.h>
+#include <sys/zfs_znode.h>
+#endif
+
+const dmu_object_type_info_t dmu_ot[DMU_OT_NUMTYPES] = {
+	{	byteswap_uint8_array,	TRUE,	"unallocated"		},
+	{	zap_byteswap,		TRUE,	"object directory"	},
+	{	byteswap_uint64_array,	TRUE,	"object array"		},
+	{	byteswap_uint8_array,	TRUE,	"packed nvlist"		},
+	{	byteswap_uint64_array,	TRUE,	"packed nvlist size"	},
+	{	byteswap_uint64_array,	TRUE,	"bplist"		},
+	{	byteswap_uint64_array,	TRUE,	"bplist header"		},
+	{	byteswap_uint64_array,	TRUE,	"SPA space map header"	},
+	{	byteswap_uint64_array,	TRUE,	"SPA space map"		},
+	{	byteswap_uint64_array,	TRUE,	"ZIL intent log"	},
+	{	dnode_buf_byteswap,	TRUE,	"DMU dnode"		},
+	{	dmu_objset_byteswap,	TRUE,	"DMU objset"		},
+	{	byteswap_uint64_array,	TRUE,	"DSL directory"		},
+	{	zap_byteswap,		TRUE,	"DSL directory child map"},
+	{	zap_byteswap,		TRUE,	"DSL dataset snap map"	},
+	{	zap_byteswap,		TRUE,	"DSL props"		},
+	{	byteswap_uint64_array,	TRUE,	"DSL dataset"		},
+	{	zfs_znode_byteswap,	TRUE,	"ZFS znode"		},
+	{	zfs_oldacl_byteswap,	TRUE,	"ZFS V0 ACL"		},
+	{	byteswap_uint8_array,	FALSE,	"ZFS plain file"	},
+	{	zap_byteswap,		TRUE,	"ZFS directory"		},
+	{	zap_byteswap,		TRUE,	"ZFS master node"	},
+	{	zap_byteswap,		TRUE,	"ZFS delete queue"	},
+	{	byteswap_uint8_array,	FALSE,	"zvol object"		},
+	{	zap_byteswap,		TRUE,	"zvol prop"		},
+	{	byteswap_uint8_array,	FALSE,	"other uint8[]"		},
+	{	byteswap_uint64_array,	FALSE,	"other uint64[]"	},
+	{	zap_byteswap,		TRUE,	"other ZAP"		},
+	{	zap_byteswap,		TRUE,	"persistent error log"	},
+	{	byteswap_uint8_array,	TRUE,	"SPA history"		},
+	{	byteswap_uint64_array,	TRUE,	"SPA history offsets"	},
+	{	zap_byteswap,		TRUE,	"Pool properties"	},
+	{	zap_byteswap,		TRUE,	"DSL permissions"	},
+	{	zfs_acl_byteswap,	TRUE,	"ZFS ACL"		},
+	{	byteswap_uint8_array,	TRUE,	"ZFS SYSACL"		},
+	{	byteswap_uint8_array,	TRUE,	"FUID table"		},
+	{	byteswap_uint64_array,	TRUE,	"FUID table size"	},
+	{	zap_byteswap,		TRUE,	"DSL dataset next clones"},
+	{	zap_byteswap,		TRUE,	"scrub work queue"	},
+};
+
+int
+dmu_buf_hold(objset_t *os, uint64_t object, uint64_t offset,
+    void *tag, dmu_buf_t **dbp)
+{
+	dnode_t *dn;
+	uint64_t blkid;
+	dmu_buf_impl_t *db;
+	int err;
+
+	err = dnode_hold(os->os, object, FTAG, &dn);
+	if (err)
+		return (err);
+	blkid = dbuf_whichblock(dn, offset);
+	rw_enter(&dn->dn_struct_rwlock, RW_READER);
+	db = dbuf_hold(dn, blkid, tag);
+	rw_exit(&dn->dn_struct_rwlock);
+	if (db == NULL) {
+		err = EIO;
+	} else {
+		err = dbuf_read(db, NULL, DB_RF_CANFAIL);
+		if (err) {
+			dbuf_rele(db, tag);
+			db = NULL;
+		}
+	}
+
+	dnode_rele(dn, FTAG);
+	*dbp = &db->db;
+	return (err);
+}
+
+int
+dmu_bonus_max(void)
+{
+	return (DN_MAX_BONUSLEN);
+}
+
+int
+dmu_set_bonus(dmu_buf_t *db, int newsize, dmu_tx_t *tx)
+{
+	dnode_t *dn = ((dmu_buf_impl_t *)db)->db_dnode;
+
+	if (dn->dn_bonus != (dmu_buf_impl_t *)db)
+		return (EINVAL);
+	if (newsize < 0 || newsize > db->db_size)
+		return (EINVAL);
+	dnode_setbonuslen(dn, newsize, tx);
+	return (0);
+}
+
+/*
+ * returns ENOENT, EIO, or 0.
+ */
+int
+dmu_bonus_hold(objset_t *os, uint64_t object, void *tag, dmu_buf_t **dbp)
+{
+	dnode_t *dn;
+	dmu_buf_impl_t *db;
+	int error;
+
+	error = dnode_hold(os->os, object, FTAG, &dn);
+	if (error)
+		return (error);
+
+	rw_enter(&dn->dn_struct_rwlock, RW_READER);
+	if (dn->dn_bonus == NULL) {
+		rw_exit(&dn->dn_struct_rwlock);
+		rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
+		if (dn->dn_bonus == NULL)
+			dbuf_create_bonus(dn);
+	}
+	db = dn->dn_bonus;
+	rw_exit(&dn->dn_struct_rwlock);
+
+	/* as long as the bonus buf is held, the dnode will be held */
+	if (refcount_add(&db->db_holds, tag) == 1)
+		VERIFY(dnode_add_ref(dn, db));
+
+	dnode_rele(dn, FTAG);
+
+	VERIFY(0 == dbuf_read(db, NULL, DB_RF_MUST_SUCCEED));
+
+	*dbp = &db->db;
+	return (0);
+}
+
+/*
+ * Note: longer-term, we should modify all of the dmu_buf_*() interfaces
+ * to take a held dnode rather than <os, object> -- the lookup is wasteful,
+ * and can induce severe lock contention when writing to several files
+ * whose dnodes are in the same block.
+ */
+static int
+dmu_buf_hold_array_by_dnode(dnode_t *dn, uint64_t offset,
+    uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp)
+{
+	dsl_pool_t *dp = NULL;
+	dmu_buf_t **dbp;
+	uint64_t blkid, nblks, i;
+	uint32_t flags;
+	int err;
+	zio_t *zio;
+	hrtime_t start;
+
+	ASSERT(length <= DMU_MAX_ACCESS);
+
+	flags = DB_RF_CANFAIL | DB_RF_NEVERWAIT;
+	if (length > zfetch_array_rd_sz)
+		flags |= DB_RF_NOPREFETCH;
+
+	rw_enter(&dn->dn_struct_rwlock, RW_READER);
+	if (dn->dn_datablkshift) {
+		int blkshift = dn->dn_datablkshift;
+		nblks = (P2ROUNDUP(offset+length, 1ULL<<blkshift) -
+		    P2ALIGN(offset, 1ULL<<blkshift)) >> blkshift;
+	} else {
+		if (offset + length > dn->dn_datablksz) {
+			zfs_panic_recover("zfs: accessing past end of object "
+			    "%llx/%llx (size=%u access=%llu+%llu)",
+			    (longlong_t)dn->dn_objset->
+			    os_dsl_dataset->ds_object,
+			    (longlong_t)dn->dn_object, dn->dn_datablksz,
+			    (longlong_t)offset, (longlong_t)length);
+			return (EIO);
+		}
+		nblks = 1;
+	}
+	dbp = kmem_zalloc(sizeof (dmu_buf_t *) * nblks, KM_SLEEP);
+
+	if (dn->dn_objset->os_dsl_dataset)
+		dp = dn->dn_objset->os_dsl_dataset->ds_dir->dd_pool;
+	if (dp && dsl_pool_sync_context(dp))
+		start = gethrtime();
+	zio = zio_root(dn->dn_objset->os_spa, NULL, NULL, ZIO_FLAG_CANFAIL);
+	blkid = dbuf_whichblock(dn, offset);
+	for (i = 0; i < nblks; i++) {
+		dmu_buf_impl_t *db = dbuf_hold(dn, blkid+i, tag);
+		if (db == NULL) {
+			rw_exit(&dn->dn_struct_rwlock);
+			dmu_buf_rele_array(dbp, nblks, tag);
+			zio_nowait(zio);
+			return (EIO);
+		}
+		/* initiate async i/o */
+		if (read) {
+			rw_exit(&dn->dn_struct_rwlock);
+			(void) dbuf_read(db, zio, flags);
+			rw_enter(&dn->dn_struct_rwlock, RW_READER);
+		}
+		dbp[i] = &db->db;
+	}
+	rw_exit(&dn->dn_struct_rwlock);
+
+	/* wait for async i/o */
+	err = zio_wait(zio);
+	/* track read overhead when we are in sync context */
+	if (dp && dsl_pool_sync_context(dp))
+		dp->dp_read_overhead += gethrtime() - start;
+	if (err) {
+		dmu_buf_rele_array(dbp, nblks, tag);
+		return (err);
+	}
+
+	/* wait for other io to complete */
+	if (read) {
+		for (i = 0; i < nblks; i++) {
+			dmu_buf_impl_t *db = (dmu_buf_impl_t *)dbp[i];
+			mutex_enter(&db->db_mtx);
+			while (db->db_state == DB_READ ||
+			    db->db_state == DB_FILL)
+				cv_wait(&db->db_changed, &db->db_mtx);
+			if (db->db_state == DB_UNCACHED)
+				err = EIO;
+			mutex_exit(&db->db_mtx);
+			if (err) {
+				dmu_buf_rele_array(dbp, nblks, tag);
+				return (err);
+			}
+		}
+	}
+
+	*numbufsp = nblks;
+	*dbpp = dbp;
+	return (0);
+}
+
+static int
+dmu_buf_hold_array(objset_t *os, uint64_t object, uint64_t offset,
+    uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp)
+{
+	dnode_t *dn;
+	int err;
+
+	err = dnode_hold(os->os, object, FTAG, &dn);
+	if (err)
+		return (err);
+
+	err = dmu_buf_hold_array_by_dnode(dn, offset, length, read, tag,
+	    numbufsp, dbpp);
+
+	dnode_rele(dn, FTAG);
+
+	return (err);
+}
+
+int
+dmu_buf_hold_array_by_bonus(dmu_buf_t *db, uint64_t offset,
+    uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp)
+{
+	dnode_t *dn = ((dmu_buf_impl_t *)db)->db_dnode;
+	int err;
+
+	err = dmu_buf_hold_array_by_dnode(dn, offset, length, read, tag,
+	    numbufsp, dbpp);
+
+	return (err);
+}
+
+void
+dmu_buf_rele_array(dmu_buf_t **dbp_fake, int numbufs, void *tag)
+{
+	int i;
+	dmu_buf_impl_t **dbp = (dmu_buf_impl_t **)dbp_fake;
+
+	if (numbufs == 0)
+		return;
+
+	for (i = 0; i < numbufs; i++) {
+		if (dbp[i])
+			dbuf_rele(dbp[i], tag);
+	}
+
+	kmem_free(dbp, sizeof (dmu_buf_t *) * numbufs);
+}
+
+void
+dmu_prefetch(objset_t *os, uint64_t object, uint64_t offset, uint64_t len)
+{
+	dnode_t *dn;
+	uint64_t blkid;
+	int nblks, i, err;
+
+	if (zfs_prefetch_disable)
+		return;
+
+	if (len == 0) {  /* they're interested in the bonus buffer */
+		dn = os->os->os_meta_dnode;
+
+		if (object == 0 || object >= DN_MAX_OBJECT)
+			return;
+
+		rw_enter(&dn->dn_struct_rwlock, RW_READER);
+		blkid = dbuf_whichblock(dn, object * sizeof (dnode_phys_t));
+		dbuf_prefetch(dn, blkid);
+		rw_exit(&dn->dn_struct_rwlock);
+		return;
+	}
+
+	/*
+	 * XXX - Note, if the dnode for the requested object is not
+	 * already cached, we will do a *synchronous* read in the
+	 * dnode_hold() call.  The same is true for any indirects.
+	 */
+	err = dnode_hold(os->os, object, FTAG, &dn);
+	if (err != 0)
+		return;
+
+	rw_enter(&dn->dn_struct_rwlock, RW_READER);
+	if (dn->dn_datablkshift) {
+		int blkshift = dn->dn_datablkshift;
+		nblks = (P2ROUNDUP(offset+len, 1<<blkshift) -
+		    P2ALIGN(offset, 1<<blkshift)) >> blkshift;
+	} else {
+		nblks = (offset < dn->dn_datablksz);
+	}
+
+	if (nblks != 0) {
+		blkid = dbuf_whichblock(dn, offset);
+		for (i = 0; i < nblks; i++)
+			dbuf_prefetch(dn, blkid+i);
+	}
+
+	rw_exit(&dn->dn_struct_rwlock);
+
+	dnode_rele(dn, FTAG);
+}
+
+static int
+get_next_chunk(dnode_t *dn, uint64_t *offset, uint64_t limit)
+{
+	uint64_t len = *offset - limit;
+	uint64_t chunk_len = dn->dn_datablksz * DMU_MAX_DELETEBLKCNT;
+	uint64_t subchunk =
+	    dn->dn_datablksz * EPB(dn->dn_indblkshift, SPA_BLKPTRSHIFT);
+
+	ASSERT(limit <= *offset);
+
+	if (len <= chunk_len) {
+		*offset = limit;
+		return (0);
+	}
+
+	ASSERT(ISP2(subchunk));
+
+	while (*offset > limit) {
+		uint64_t initial_offset = P2ROUNDUP(*offset, subchunk);
+		uint64_t delta;
+		int err;
+
+		/* skip over allocated data */
+		err = dnode_next_offset(dn,
+		    DNODE_FIND_HOLE|DNODE_FIND_BACKWARDS, offset, 1, 1, 0);
+		if (err == ESRCH)
+			*offset = limit;
+		else if (err)
+			return (err);
+
+		ASSERT3U(*offset, <=, initial_offset);
+		*offset = P2ALIGN(*offset, subchunk);
+		delta = initial_offset - *offset;
+		if (delta >= chunk_len) {
+			*offset += delta - chunk_len;
+			return (0);
+		}
+		chunk_len -= delta;
+
+		/* skip over unallocated data */
+		err = dnode_next_offset(dn,
+		    DNODE_FIND_BACKWARDS, offset, 1, 1, 0);
+		if (err == ESRCH)
+			*offset = limit;
+		else if (err)
+			return (err);
+
+		if (*offset < limit)
+			*offset = limit;
+		ASSERT3U(*offset, <, initial_offset);
+	}
+	return (0);
+}
+
+static int
+dmu_free_long_range_impl(objset_t *os, dnode_t *dn, uint64_t offset,
+    uint64_t length, boolean_t free_dnode)
+{
+	dmu_tx_t *tx;
+	uint64_t object_size, start, end, len;
+	boolean_t trunc = (length == DMU_OBJECT_END);
+	int align, err;
+
+	align = 1 << dn->dn_datablkshift;
+	ASSERT(align > 0);
+	object_size = align == 1 ? dn->dn_datablksz :
+	    (dn->dn_maxblkid + 1) << dn->dn_datablkshift;
+
+	if (trunc || (end = offset + length) > object_size)
+		end = object_size;
+	if (end <= offset)
+		return (0);
+	length = end - offset;
+
+	while (length) {
+		start = end;
+		err = get_next_chunk(dn, &start, offset);
+		if (err)
+			return (err);
+		len = trunc ? DMU_OBJECT_END : end - start;
+
+		tx = dmu_tx_create(os);
+		dmu_tx_hold_free(tx, dn->dn_object, start, len);
+		err = dmu_tx_assign(tx, TXG_WAIT);
+		if (err) {
+			dmu_tx_abort(tx);
+			return (err);
+		}
+
+		dnode_free_range(dn, start, trunc ? -1 : len, tx);
+
+		if (start == 0 && free_dnode) {
+			ASSERT(trunc);
+			dnode_free(dn, tx);
+		}
+
+		length -= end - start;
+
+		dmu_tx_commit(tx);
+		end = start;
+	}
+	return (0);
+}
+
+int
+dmu_free_long_range(objset_t *os, uint64_t object,
+    uint64_t offset, uint64_t length)
+{
+	dnode_t *dn;
+	int err;
+
+	err = dnode_hold(os->os, object, FTAG, &dn);
+	if (err != 0)
+		return (err);
+	err = dmu_free_long_range_impl(os, dn, offset, length, FALSE);
+	dnode_rele(dn, FTAG);
+	return (err);
+}
+
+int
+dmu_free_object(objset_t *os, uint64_t object)
+{
+	dnode_t *dn;
+	dmu_tx_t *tx;
+	int err;
+
+	err = dnode_hold_impl(os->os, object, DNODE_MUST_BE_ALLOCATED,
+	    FTAG, &dn);
+	if (err != 0)
+		return (err);
+	if (dn->dn_nlevels == 1) {
+		tx = dmu_tx_create(os);
+		dmu_tx_hold_bonus(tx, object);
+		dmu_tx_hold_free(tx, dn->dn_object, 0, DMU_OBJECT_END);
+		err = dmu_tx_assign(tx, TXG_WAIT);
+		if (err == 0) {
+			dnode_free_range(dn, 0, DMU_OBJECT_END, tx);
+			dnode_free(dn, tx);
+			dmu_tx_commit(tx);
+		} else {
+			dmu_tx_abort(tx);
+		}
+	} else {
+		err = dmu_free_long_range_impl(os, dn, 0, DMU_OBJECT_END, TRUE);
+	}
+	dnode_rele(dn, FTAG);
+	return (err);
+}
+
+int
+dmu_free_range(objset_t *os, uint64_t object, uint64_t offset,
+    uint64_t size, dmu_tx_t *tx)
+{
+	dnode_t *dn;
+	int err = dnode_hold(os->os, object, FTAG, &dn);
+	if (err)
+		return (err);
+	ASSERT(offset < UINT64_MAX);
+	ASSERT(size == -1ULL || size <= UINT64_MAX - offset);
+	dnode_free_range(dn, offset, size, tx);
+	dnode_rele(dn, FTAG);
+	return (0);
+}
+
+int
+dmu_read(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
+    void *buf)
+{
+	dnode_t *dn;
+	dmu_buf_t **dbp;
+	int numbufs, i, err;
+
+	err = dnode_hold(os->os, object, FTAG, &dn);
+	if (err)
+		return (err);
+
+	/*
+	 * Deal with odd block sizes, where there can't be data past the first
+	 * block.  If we ever do the tail block optimization, we will need to
+	 * handle that here as well.
+	 */
+	if (dn->dn_datablkshift == 0) {
+		int newsz = offset > dn->dn_datablksz ? 0 :
+		    MIN(size, dn->dn_datablksz - offset);
+		bzero((char *)buf + newsz, size - newsz);
+		size = newsz;
+	}
+
+	while (size > 0) {
+		uint64_t mylen = MIN(size, DMU_MAX_ACCESS / 2);
+
+		/*
+		 * NB: we could do this block-at-a-time, but it's nice
+		 * to be reading in parallel.
+		 */
+		err = dmu_buf_hold_array_by_dnode(dn, offset, mylen,
+		    TRUE, FTAG, &numbufs, &dbp);
+		if (err)
+			break;
+
+		for (i = 0; i < numbufs; i++) {
+			int tocpy;
+			int bufoff;
+			dmu_buf_t *db = dbp[i];
+
+			ASSERT(size > 0);
+
+			bufoff = offset - db->db_offset;
+			tocpy = (int)MIN(db->db_size - bufoff, size);
+
+			bcopy((char *)db->db_data + bufoff, buf, tocpy);
+
+			offset += tocpy;
+			size -= tocpy;
+			buf = (char *)buf + tocpy;
+		}
+		dmu_buf_rele_array(dbp, numbufs, FTAG);
+	}
+	dnode_rele(dn, FTAG);
+	return (err);
+}
+
+void
+dmu_write(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
+    const void *buf, dmu_tx_t *tx)
+{
+	dmu_buf_t **dbp;
+	int numbufs, i;
+
+	if (size == 0)
+		return;
+
+	VERIFY(0 == dmu_buf_hold_array(os, object, offset, size,
+	    FALSE, FTAG, &numbufs, &dbp));
+
+	for (i = 0; i < numbufs; i++) {
+		int tocpy;
+		int bufoff;
+		dmu_buf_t *db = dbp[i];
+
+		ASSERT(size > 0);
+
+		bufoff = offset - db->db_offset;
+		tocpy = (int)MIN(db->db_size - bufoff, size);
+
+		ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
+
+		if (tocpy == db->db_size)
+			dmu_buf_will_fill(db, tx);
+		else
+			dmu_buf_will_dirty(db, tx);
+
+		bcopy(buf, (char *)db->db_data + bufoff, tocpy);
+
+		if (tocpy == db->db_size)
+			dmu_buf_fill_done(db, tx);
+
+		offset += tocpy;
+		size -= tocpy;
+		buf = (char *)buf + tocpy;
+	}
+	dmu_buf_rele_array(dbp, numbufs, FTAG);
+}
+
+void
+dmu_prealloc(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
+    dmu_tx_t *tx)
+{
+	dmu_buf_t **dbp;
+	int numbufs, i;
+
+	if (size == 0)
+		return;
+
+	VERIFY(0 == dmu_buf_hold_array(os, object, offset, size,
+	    FALSE, FTAG, &numbufs, &dbp));
+
+	for (i = 0; i < numbufs; i++) {
+		dmu_buf_t *db = dbp[i];
+
+		dmu_buf_will_not_fill(db, tx);
+	}
+	dmu_buf_rele_array(dbp, numbufs, FTAG);
+}
+
+#ifdef _KERNEL
+int
+dmu_read_uio(objset_t *os, uint64_t object, uio_t *uio, uint64_t size)
+{
+	dmu_buf_t **dbp;
+	int numbufs, i, err;
+
+	/*
+	 * NB: we could do this block-at-a-time, but it's nice
+	 * to be reading in parallel.
+	 */
+	err = dmu_buf_hold_array(os, object, uio->uio_loffset, size, TRUE, FTAG,
+	    &numbufs, &dbp);
+	if (err)
+		return (err);
+
+	for (i = 0; i < numbufs; i++) {
+		int tocpy;
+		int bufoff;
+		dmu_buf_t *db = dbp[i];
+
+		ASSERT(size > 0);
+
+		bufoff = uio->uio_loffset - db->db_offset;
+		tocpy = (int)MIN(db->db_size - bufoff, size);
+
+		err = uiomove((char *)db->db_data + bufoff, tocpy,
+		    UIO_READ, uio);
+		if (err)
+			break;
+
+		size -= tocpy;
+	}
+	dmu_buf_rele_array(dbp, numbufs, FTAG);
+
+	return (err);
+}
+
+int
+dmu_write_uio(objset_t *os, uint64_t object, uio_t *uio, uint64_t size,
+    dmu_tx_t *tx)
+{
+	dmu_buf_t **dbp;
+	int numbufs, i;
+	int err = 0;
+
+	if (size == 0)
+		return (0);
+
+	err = dmu_buf_hold_array(os, object, uio->uio_loffset, size,
+	    FALSE, FTAG, &numbufs, &dbp);
+	if (err)
+		return (err);
+
+	for (i = 0; i < numbufs; i++) {
+		int tocpy;
+		int bufoff;
+		dmu_buf_t *db = dbp[i];
+
+		ASSERT(size > 0);
+
+		bufoff = uio->uio_loffset - db->db_offset;
+		tocpy = (int)MIN(db->db_size - bufoff, size);
+
+		ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
+
+		if (tocpy == db->db_size)
+			dmu_buf_will_fill(db, tx);
+		else
+			dmu_buf_will_dirty(db, tx);
+
+		/*
+		 * XXX uiomove could block forever (eg. nfs-backed
+		 * pages).  There needs to be a uiolockdown() function
+		 * to lock the pages in memory, so that uiomove won't
+		 * block.
+		 */
+		err = uiomove((char *)db->db_data + bufoff, tocpy,
+		    UIO_WRITE, uio);
+
+		if (tocpy == db->db_size)
+			dmu_buf_fill_done(db, tx);
+
+		if (err)
+			break;
+
+		size -= tocpy;
+	}
+	dmu_buf_rele_array(dbp, numbufs, FTAG);
+	return (err);
+}
+
+int
+dmu_write_pages(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
+    page_t *pp, dmu_tx_t *tx)
+{
+	dmu_buf_t **dbp;
+	int numbufs, i;
+	int err;
+
+	if (size == 0)
+		return (0);
+
+	err = dmu_buf_hold_array(os, object, offset, size,
+	    FALSE, FTAG, &numbufs, &dbp);
+	if (err)
+		return (err);
+
+	for (i = 0; i < numbufs; i++) {
+		int tocpy, copied, thiscpy;
+		int bufoff;
+		dmu_buf_t *db = dbp[i];
+		caddr_t va;
+
+		ASSERT(size > 0);
+		ASSERT3U(db->db_size, >=, PAGESIZE);
+
+		bufoff = offset - db->db_offset;
+		tocpy = (int)MIN(db->db_size - bufoff, size);
+
+		ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
+
+		if (tocpy == db->db_size)
+			dmu_buf_will_fill(db, tx);
+		else
+			dmu_buf_will_dirty(db, tx);
+
+		for (copied = 0; copied < tocpy; copied += PAGESIZE) {
+			ASSERT3U(pp->p_offset, ==, db->db_offset + bufoff);
+			thiscpy = MIN(PAGESIZE, tocpy - copied);
+			va = zfs_map_page(pp, S_READ);
+			bcopy(va, (char *)db->db_data + bufoff, thiscpy);
+			zfs_unmap_page(pp, va);
+			pp = pp->p_next;
+			bufoff += PAGESIZE;
+		}
+
+		if (tocpy == db->db_size)
+			dmu_buf_fill_done(db, tx);
+
+		if (err)
+			break;
+
+		offset += tocpy;
+		size -= tocpy;
+	}
+	dmu_buf_rele_array(dbp, numbufs, FTAG);
+	return (err);
+}
+#endif
+
+typedef struct {
+	dbuf_dirty_record_t	*dr;
+	dmu_sync_cb_t		*done;
+	void			*arg;
+} dmu_sync_arg_t;
+
+/* ARGSUSED */
+static void
+dmu_sync_ready(zio_t *zio, arc_buf_t *buf, void *varg)
+{
+	blkptr_t *bp = zio->io_bp;
+
+	if (!BP_IS_HOLE(bp)) {
+		dmu_sync_arg_t *in = varg;
+		dbuf_dirty_record_t *dr = in->dr;
+		dmu_buf_impl_t *db = dr->dr_dbuf;
+		ASSERT(BP_GET_TYPE(bp) == db->db_dnode->dn_type);
+		ASSERT(BP_GET_LEVEL(bp) == 0);
+		bp->blk_fill = 1;
+	}
+}
+
+/* ARGSUSED */
+static void
+dmu_sync_done(zio_t *zio, arc_buf_t *buf, void *varg)
+{
+	dmu_sync_arg_t *in = varg;
+	dbuf_dirty_record_t *dr = in->dr;
+	dmu_buf_impl_t *db = dr->dr_dbuf;
+	dmu_sync_cb_t *done = in->done;
+
+	mutex_enter(&db->db_mtx);
+	ASSERT(dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC);
+	dr->dt.dl.dr_overridden_by = *zio->io_bp; /* structure assignment */
+	dr->dt.dl.dr_override_state = DR_OVERRIDDEN;
+	cv_broadcast(&db->db_changed);
+	mutex_exit(&db->db_mtx);
+
+	if (done)
+		done(&(db->db), in->arg);
+
+	kmem_free(in, sizeof (dmu_sync_arg_t));
+}
+
+/*
+ * Intent log support: sync the block associated with db to disk.
+ * N.B. and XXX: the caller is responsible for making sure that the
+ * data isn't changing while dmu_sync() is writing it.
+ *
+ * Return values:
+ *
+ *	EEXIST: this txg has already been synced, so there's nothing to to.
+ *		The caller should not log the write.
+ *
+ *	ENOENT: the block was dbuf_free_range()'d, so there's nothing to do.
+ *		The caller should not log the write.
+ *
+ *	EALREADY: this block is already in the process of being synced.
+ *		The caller should track its progress (somehow).
+ *
+ *	EINPROGRESS: the IO has been initiated.
+ *		The caller should log this blkptr in the callback.
+ *
+ *	0: completed.  Sets *bp to the blkptr just written.
+ *		The caller should log this blkptr immediately.
+ */
+int
+dmu_sync(zio_t *pio, dmu_buf_t *db_fake,
+    blkptr_t *bp, uint64_t txg, dmu_sync_cb_t *done, void *arg)
+{
+	dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
+	objset_impl_t *os = db->db_objset;
+	dsl_pool_t *dp = os->os_dsl_dataset->ds_dir->dd_pool;
+	tx_state_t *tx = &dp->dp_tx;
+	dbuf_dirty_record_t *dr;
+	dmu_sync_arg_t *in;
+	zbookmark_t zb;
+	writeprops_t wp = { 0 };
+	zio_t *zio;
+	int err;
+
+	ASSERT(BP_IS_HOLE(bp));
+	ASSERT(txg != 0);
+
+	dprintf("dmu_sync txg=%llu, s,o,q %llu %llu %llu\n",
+	    txg, tx->tx_synced_txg, tx->tx_open_txg, tx->tx_quiesced_txg);
+
+	/*
+	 * XXX - would be nice if we could do this without suspending...
+	 */
+	txg_suspend(dp);
+
+	/*
+	 * If this txg already synced, there's nothing to do.
+	 */
+	if (txg <= tx->tx_synced_txg) {
+		txg_resume(dp);
+		/*
+		 * If we're running ziltest, we need the blkptr regardless.
+		 */
+		if (txg > spa_freeze_txg(dp->dp_spa)) {
+			/* if db_blkptr == NULL, this was an empty write */
+			if (db->db_blkptr)
+				*bp = *db->db_blkptr; /* structure assignment */
+			return (0);
+		}
+		return (EEXIST);
+	}
+
+	mutex_enter(&db->db_mtx);
+
+	if (txg == tx->tx_syncing_txg) {
+		while (db->db_data_pending) {
+			/*
+			 * IO is in-progress.  Wait for it to finish.
+			 * XXX - would be nice to be able to somehow "attach"
+			 * this zio to the parent zio passed in.
+			 */
+			cv_wait(&db->db_changed, &db->db_mtx);
+			if (!db->db_data_pending &&
+			    db->db_blkptr && BP_IS_HOLE(db->db_blkptr)) {
+				/*
+				 * IO was compressed away
+				 */
+				*bp = *db->db_blkptr; /* structure assignment */
+				mutex_exit(&db->db_mtx);
+				txg_resume(dp);
+				return (0);
+			}
+			ASSERT(db->db_data_pending ||
+			    (db->db_blkptr && db->db_blkptr->blk_birth == txg));
+		}
+
+		if (db->db_blkptr && db->db_blkptr->blk_birth == txg) {
+			/*
+			 * IO is already completed.
+			 */
+			*bp = *db->db_blkptr; /* structure assignment */
+			mutex_exit(&db->db_mtx);
+			txg_resume(dp);
+			return (0);
+		}
+	}
+
+	dr = db->db_last_dirty;
+	while (dr && dr->dr_txg > txg)
+		dr = dr->dr_next;
+	if (dr == NULL || dr->dr_txg < txg) {
+		/*
+		 * This dbuf isn't dirty, must have been free_range'd.
+		 * There's no need to log writes to freed blocks, so we're done.
+		 */
+		mutex_exit(&db->db_mtx);
+		txg_resume(dp);
+		return (ENOENT);
+	}
+
+	ASSERT(dr->dr_txg == txg);
+	if (dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC) {
+		/*
+		 * We have already issued a sync write for this buffer.
+		 */
+		mutex_exit(&db->db_mtx);
+		txg_resume(dp);
+		return (EALREADY);
+	} else if (dr->dt.dl.dr_override_state == DR_OVERRIDDEN) {
+		/*
+		 * This buffer has already been synced.  It could not
+		 * have been dirtied since, or we would have cleared the state.
+		 */
+		*bp = dr->dt.dl.dr_overridden_by; /* structure assignment */
+		mutex_exit(&db->db_mtx);
+		txg_resume(dp);
+		return (0);
+	}
+
+	dr->dt.dl.dr_override_state = DR_IN_DMU_SYNC;
+	in = kmem_alloc(sizeof (dmu_sync_arg_t), KM_SLEEP);
+	in->dr = dr;
+	in->done = done;
+	in->arg = arg;
+	mutex_exit(&db->db_mtx);
+	txg_resume(dp);
+
+	zb.zb_objset = os->os_dsl_dataset->ds_object;
+	zb.zb_object = db->db.db_object;
+	zb.zb_level = db->db_level;
+	zb.zb_blkid = db->db_blkid;
+
+	wp.wp_type = db->db_dnode->dn_type;
+	wp.wp_level = db->db_level;
+	wp.wp_copies = os->os_copies;
+	wp.wp_dnchecksum = db->db_dnode->dn_checksum;
+	wp.wp_oschecksum = os->os_checksum;
+	wp.wp_dncompress = db->db_dnode->dn_compress;
+	wp.wp_oscompress = os->os_compress;
+
+	ASSERT(BP_IS_HOLE(bp));
+
+	zio = arc_write(pio, os->os_spa, &wp, DBUF_IS_L2CACHEABLE(db),
+	    txg, bp, dr->dt.dl.dr_data, dmu_sync_ready, dmu_sync_done, in,
+	    ZIO_PRIORITY_SYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb);
+	if (pio) {
+		zio_nowait(zio);
+		err = EINPROGRESS;
+	} else {
+		err = zio_wait(zio);
+		ASSERT(err == 0);
+	}
+	return (err);
+}
+
+int
+dmu_object_set_blocksize(objset_t *os, uint64_t object, uint64_t size, int ibs,
+	dmu_tx_t *tx)
+{
+	dnode_t *dn;
+	int err;
+
+	err = dnode_hold(os->os, object, FTAG, &dn);
+	if (err)
+		return (err);
+	err = dnode_set_blksz(dn, size, ibs, tx);
+	dnode_rele(dn, FTAG);
+	return (err);
+}
+
+void
+dmu_object_set_checksum(objset_t *os, uint64_t object, uint8_t checksum,
+	dmu_tx_t *tx)
+{
+	dnode_t *dn;
+
+	/* XXX assumes dnode_hold will not get an i/o error */
+	(void) dnode_hold(os->os, object, FTAG, &dn);
+	ASSERT(checksum < ZIO_CHECKSUM_FUNCTIONS);
+	dn->dn_checksum = checksum;
+	dnode_setdirty(dn, tx);
+	dnode_rele(dn, FTAG);
+}
+
+void
+dmu_object_set_compress(objset_t *os, uint64_t object, uint8_t compress,
+	dmu_tx_t *tx)
+{
+	dnode_t *dn;
+
+	/* XXX assumes dnode_hold will not get an i/o error */
+	(void) dnode_hold(os->os, object, FTAG, &dn);
+	ASSERT(compress < ZIO_COMPRESS_FUNCTIONS);
+	dn->dn_compress = compress;
+	dnode_setdirty(dn, tx);
+	dnode_rele(dn, FTAG);
+}
+
+int
+dmu_offset_next(objset_t *os, uint64_t object, boolean_t hole, uint64_t *off)
+{
+	dnode_t *dn;
+	int i, err;
+
+	err = dnode_hold(os->os, object, FTAG, &dn);
+	if (err)
+		return (err);
+	/*
+	 * Sync any current changes before
+	 * we go trundling through the block pointers.
+	 */
+	for (i = 0; i < TXG_SIZE; i++) {
+		if (list_link_active(&dn->dn_dirty_link[i]))
+			break;
+	}
+	if (i != TXG_SIZE) {
+		dnode_rele(dn, FTAG);
+		txg_wait_synced(dmu_objset_pool(os), 0);
+		err = dnode_hold(os->os, object, FTAG, &dn);
+		if (err)
+			return (err);
+	}
+
+	err = dnode_next_offset(dn, (hole ? DNODE_FIND_HOLE : 0), off, 1, 1, 0);
+	dnode_rele(dn, FTAG);
+
+	return (err);
+}
+
+void
+dmu_object_info_from_dnode(dnode_t *dn, dmu_object_info_t *doi)
+{
+	rw_enter(&dn->dn_struct_rwlock, RW_READER);
+	mutex_enter(&dn->dn_mtx);
+
+	doi->doi_data_block_size = dn->dn_datablksz;
+	doi->doi_metadata_block_size = dn->dn_indblkshift ?
+	    1ULL << dn->dn_indblkshift : 0;
+	doi->doi_indirection = dn->dn_nlevels;
+	doi->doi_checksum = dn->dn_checksum;
+	doi->doi_compress = dn->dn_compress;
+	doi->doi_physical_blks = (DN_USED_BYTES(dn->dn_phys) +
+	    SPA_MINBLOCKSIZE/2) >> SPA_MINBLOCKSHIFT;
+	doi->doi_max_block_offset = dn->dn_phys->dn_maxblkid;
+	doi->doi_type = dn->dn_type;
+	doi->doi_bonus_size = dn->dn_bonuslen;
+	doi->doi_bonus_type = dn->dn_bonustype;
+
+	mutex_exit(&dn->dn_mtx);
+	rw_exit(&dn->dn_struct_rwlock);
+}
+
+/*
+ * Get information on a DMU object.
+ * If doi is NULL, just indicates whether the object exists.
+ */
+int
+dmu_object_info(objset_t *os, uint64_t object, dmu_object_info_t *doi)
+{
+	dnode_t *dn;
+	int err = dnode_hold(os->os, object, FTAG, &dn);
+
+	if (err)
+		return (err);
+
+	if (doi != NULL)
+		dmu_object_info_from_dnode(dn, doi);
+
+	dnode_rele(dn, FTAG);
+	return (0);
+}
+
+/*
+ * As above, but faster; can be used when you have a held dbuf in hand.
+ */
+void
+dmu_object_info_from_db(dmu_buf_t *db, dmu_object_info_t *doi)
+{
+	dmu_object_info_from_dnode(((dmu_buf_impl_t *)db)->db_dnode, doi);
+}
+
+/*
+ * Faster still when you only care about the size.
+ * This is specifically optimized for zfs_getattr().
+ */
+void
+dmu_object_size_from_db(dmu_buf_t *db, uint32_t *blksize, u_longlong_t *nblk512)
+{
+	dnode_t *dn = ((dmu_buf_impl_t *)db)->db_dnode;
+
+	*blksize = dn->dn_datablksz;
+	/* add 1 for dnode space */
+	*nblk512 = ((DN_USED_BYTES(dn->dn_phys) + SPA_MINBLOCKSIZE/2) >>
+	    SPA_MINBLOCKSHIFT) + 1;
+}
+
+void
+byteswap_uint64_array(void *vbuf, size_t size)
+{
+	uint64_t *buf = vbuf;
+	size_t count = size >> 3;
+	int i;
+
+	ASSERT((size & 7) == 0);
+
+	for (i = 0; i < count; i++)
+		buf[i] = BSWAP_64(buf[i]);
+}
+
+void
+byteswap_uint32_array(void *vbuf, size_t size)
+{
+	uint32_t *buf = vbuf;
+	size_t count = size >> 2;
+	int i;
+
+	ASSERT((size & 3) == 0);
+
+	for (i = 0; i < count; i++)
+		buf[i] = BSWAP_32(buf[i]);
+}
+
+void
+byteswap_uint16_array(void *vbuf, size_t size)
+{
+	uint16_t *buf = vbuf;
+	size_t count = size >> 1;
+	int i;
+
+	ASSERT((size & 1) == 0);
+
+	for (i = 0; i < count; i++)
+		buf[i] = BSWAP_16(buf[i]);
+}
+
+/* ARGSUSED */
+void
+byteswap_uint8_array(void *vbuf, size_t size)
+{
+}
+
+void
+dmu_init(void)
+{
+	dbuf_init();
+	dnode_init();
+	arc_init();
+	l2arc_init();
+}
+
+void
+dmu_fini(void)
+{
+	arc_fini();
+	dnode_fini();
+	dbuf_fini();
+	l2arc_fini();
+}