Move the world out of /zfs/ and seperate out module build tree
[zfs.git] / module / zfs / dmu_send.c
diff --git a/module/zfs/dmu_send.c b/module/zfs/dmu_send.c
new file mode 100644 (file)
index 0000000..857b9a3
--- /dev/null
@@ -0,0 +1,1181 @@
+/*
+ * 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/zfs_ioctl.h>
+#include <sys/zap.h>
+#include <sys/zio_checksum.h>
+
+static char *dmu_recv_tag = "dmu_recv_tag";
+
+struct backuparg {
+       dmu_replay_record_t *drr;
+       vnode_t *vp;
+       offset_t *off;
+       objset_t *os;
+       zio_cksum_t zc;
+       int err;
+};
+
+static int
+dump_bytes(struct backuparg *ba, void *buf, int len)
+{
+       ssize_t resid; /* have to get resid to get detailed errno */
+       ASSERT3U(len % 8, ==, 0);
+
+       fletcher_4_incremental_native(buf, len, &ba->zc);
+       ba->err = vn_rdwr(UIO_WRITE, ba->vp,
+           (caddr_t)buf, len,
+           0, UIO_SYSSPACE, FAPPEND, RLIM64_INFINITY, CRED(), &resid);
+       *ba->off += len;
+       return (ba->err);
+}
+
+static int
+dump_free(struct backuparg *ba, uint64_t object, uint64_t offset,
+    uint64_t length)
+{
+       /* write a FREE record */
+       bzero(ba->drr, sizeof (dmu_replay_record_t));
+       ba->drr->drr_type = DRR_FREE;
+       ba->drr->drr_u.drr_free.drr_object = object;
+       ba->drr->drr_u.drr_free.drr_offset = offset;
+       ba->drr->drr_u.drr_free.drr_length = length;
+
+       if (dump_bytes(ba, ba->drr, sizeof (dmu_replay_record_t)))
+               return (EINTR);
+       return (0);
+}
+
+static int
+dump_data(struct backuparg *ba, dmu_object_type_t type,
+    uint64_t object, uint64_t offset, int blksz, void *data)
+{
+       /* write a DATA record */
+       bzero(ba->drr, sizeof (dmu_replay_record_t));
+       ba->drr->drr_type = DRR_WRITE;
+       ba->drr->drr_u.drr_write.drr_object = object;
+       ba->drr->drr_u.drr_write.drr_type = type;
+       ba->drr->drr_u.drr_write.drr_offset = offset;
+       ba->drr->drr_u.drr_write.drr_length = blksz;
+
+       if (dump_bytes(ba, ba->drr, sizeof (dmu_replay_record_t)))
+               return (EINTR);
+       if (dump_bytes(ba, data, blksz))
+               return (EINTR);
+       return (0);
+}
+
+static int
+dump_freeobjects(struct backuparg *ba, uint64_t firstobj, uint64_t numobjs)
+{
+       /* write a FREEOBJECTS record */
+       bzero(ba->drr, sizeof (dmu_replay_record_t));
+       ba->drr->drr_type = DRR_FREEOBJECTS;
+       ba->drr->drr_u.drr_freeobjects.drr_firstobj = firstobj;
+       ba->drr->drr_u.drr_freeobjects.drr_numobjs = numobjs;
+
+       if (dump_bytes(ba, ba->drr, sizeof (dmu_replay_record_t)))
+               return (EINTR);
+       return (0);
+}
+
+static int
+dump_dnode(struct backuparg *ba, uint64_t object, dnode_phys_t *dnp)
+{
+       if (dnp == NULL || dnp->dn_type == DMU_OT_NONE)
+               return (dump_freeobjects(ba, object, 1));
+
+       /* write an OBJECT record */
+       bzero(ba->drr, sizeof (dmu_replay_record_t));
+       ba->drr->drr_type = DRR_OBJECT;
+       ba->drr->drr_u.drr_object.drr_object = object;
+       ba->drr->drr_u.drr_object.drr_type = dnp->dn_type;
+       ba->drr->drr_u.drr_object.drr_bonustype = dnp->dn_bonustype;
+       ba->drr->drr_u.drr_object.drr_blksz =
+           dnp->dn_datablkszsec << SPA_MINBLOCKSHIFT;
+       ba->drr->drr_u.drr_object.drr_bonuslen = dnp->dn_bonuslen;
+       ba->drr->drr_u.drr_object.drr_checksum = dnp->dn_checksum;
+       ba->drr->drr_u.drr_object.drr_compress = dnp->dn_compress;
+
+       if (dump_bytes(ba, ba->drr, sizeof (dmu_replay_record_t)))
+               return (EINTR);
+
+       if (dump_bytes(ba, DN_BONUS(dnp), P2ROUNDUP(dnp->dn_bonuslen, 8)))
+               return (EINTR);
+
+       /* free anything past the end of the file */
+       if (dump_free(ba, object, (dnp->dn_maxblkid + 1) *
+           (dnp->dn_datablkszsec << SPA_MINBLOCKSHIFT), -1ULL))
+               return (EINTR);
+       if (ba->err)
+               return (EINTR);
+       return (0);
+}
+
+#define        BP_SPAN(dnp, level) \
+       (((uint64_t)dnp->dn_datablkszsec) << (SPA_MINBLOCKSHIFT + \
+       (level) * (dnp->dn_indblkshift - SPA_BLKPTRSHIFT)))
+
+static int
+backup_cb(spa_t *spa, blkptr_t *bp, const zbookmark_t *zb,
+    const dnode_phys_t *dnp, void *arg)
+{
+       struct backuparg *ba = arg;
+       dmu_object_type_t type = bp ? BP_GET_TYPE(bp) : DMU_OT_NONE;
+       int err = 0;
+
+       if (issig(JUSTLOOKING) && issig(FORREAL))
+               return (EINTR);
+
+       if (bp == NULL && zb->zb_object == 0) {
+               uint64_t span = BP_SPAN(dnp, zb->zb_level);
+               uint64_t dnobj = (zb->zb_blkid * span) >> DNODE_SHIFT;
+               err = dump_freeobjects(ba, dnobj, span >> DNODE_SHIFT);
+       } else if (bp == NULL) {
+               uint64_t span = BP_SPAN(dnp, zb->zb_level);
+               err = dump_free(ba, zb->zb_object, zb->zb_blkid * span, span);
+       } else if (zb->zb_level > 0 || type == DMU_OT_OBJSET) {
+               return (0);
+       } else if (type == DMU_OT_DNODE) {
+               dnode_phys_t *blk;
+               int i;
+               int blksz = BP_GET_LSIZE(bp);
+               uint32_t aflags = ARC_WAIT;
+               arc_buf_t *abuf;
+
+               if (arc_read_nolock(NULL, spa, bp,
+                   arc_getbuf_func, &abuf, ZIO_PRIORITY_ASYNC_READ,
+                   ZIO_FLAG_CANFAIL, &aflags, zb) != 0)
+                       return (EIO);
+
+               blk = abuf->b_data;
+               for (i = 0; i < blksz >> DNODE_SHIFT; i++) {
+                       uint64_t dnobj = (zb->zb_blkid <<
+                           (DNODE_BLOCK_SHIFT - DNODE_SHIFT)) + i;
+                       err = dump_dnode(ba, dnobj, blk+i);
+                       if (err)
+                               break;
+               }
+               (void) arc_buf_remove_ref(abuf, &abuf);
+       } else { /* it's a level-0 block of a regular object */
+               uint32_t aflags = ARC_WAIT;
+               arc_buf_t *abuf;
+               int blksz = BP_GET_LSIZE(bp);
+
+               if (arc_read_nolock(NULL, spa, bp,
+                   arc_getbuf_func, &abuf, ZIO_PRIORITY_ASYNC_READ,
+                   ZIO_FLAG_CANFAIL, &aflags, zb) != 0)
+                       return (EIO);
+
+               err = dump_data(ba, type, zb->zb_object, zb->zb_blkid * blksz,
+                   blksz, abuf->b_data);
+               (void) arc_buf_remove_ref(abuf, &abuf);
+       }
+
+       ASSERT(err == 0 || err == EINTR);
+       return (err);
+}
+
+int
+dmu_sendbackup(objset_t *tosnap, objset_t *fromsnap, boolean_t fromorigin,
+    vnode_t *vp, offset_t *off)
+{
+       dsl_dataset_t *ds = tosnap->os->os_dsl_dataset;
+       dsl_dataset_t *fromds = fromsnap ? fromsnap->os->os_dsl_dataset : NULL;
+       dmu_replay_record_t *drr;
+       struct backuparg ba;
+       int err;
+       uint64_t fromtxg = 0;
+
+       /* tosnap must be a snapshot */
+       if (ds->ds_phys->ds_next_snap_obj == 0)
+               return (EINVAL);
+
+       /* fromsnap must be an earlier snapshot from the same fs as tosnap */
+       if (fromds && (ds->ds_dir != fromds->ds_dir ||
+           fromds->ds_phys->ds_creation_txg >= ds->ds_phys->ds_creation_txg))
+               return (EXDEV);
+
+       if (fromorigin) {
+               dsl_pool_t *dp = ds->ds_dir->dd_pool;
+
+               if (fromsnap)
+                       return (EINVAL);
+
+               if (dsl_dir_is_clone(ds->ds_dir)) {
+                       rw_enter(&dp->dp_config_rwlock, RW_READER);
+                       err = dsl_dataset_hold_obj(dp,
+                           ds->ds_dir->dd_phys->dd_origin_obj, FTAG, &fromds);
+                       rw_exit(&dp->dp_config_rwlock);
+                       if (err)
+                               return (err);
+               } else {
+                       fromorigin = B_FALSE;
+               }
+       }
+
+
+       drr = kmem_zalloc(sizeof (dmu_replay_record_t), KM_SLEEP);
+       drr->drr_type = DRR_BEGIN;
+       drr->drr_u.drr_begin.drr_magic = DMU_BACKUP_MAGIC;
+       drr->drr_u.drr_begin.drr_version = DMU_BACKUP_STREAM_VERSION;
+       drr->drr_u.drr_begin.drr_creation_time =
+           ds->ds_phys->ds_creation_time;
+       drr->drr_u.drr_begin.drr_type = tosnap->os->os_phys->os_type;
+       if (fromorigin)
+               drr->drr_u.drr_begin.drr_flags |= DRR_FLAG_CLONE;
+       drr->drr_u.drr_begin.drr_toguid = ds->ds_phys->ds_guid;
+       if (ds->ds_phys->ds_flags & DS_FLAG_CI_DATASET)
+               drr->drr_u.drr_begin.drr_flags |= DRR_FLAG_CI_DATA;
+
+       if (fromds)
+               drr->drr_u.drr_begin.drr_fromguid = fromds->ds_phys->ds_guid;
+       dsl_dataset_name(ds, drr->drr_u.drr_begin.drr_toname);
+
+       if (fromds)
+               fromtxg = fromds->ds_phys->ds_creation_txg;
+       if (fromorigin)
+               dsl_dataset_rele(fromds, FTAG);
+
+       ba.drr = drr;
+       ba.vp = vp;
+       ba.os = tosnap;
+       ba.off = off;
+       ZIO_SET_CHECKSUM(&ba.zc, 0, 0, 0, 0);
+
+       if (dump_bytes(&ba, drr, sizeof (dmu_replay_record_t))) {
+               kmem_free(drr, sizeof (dmu_replay_record_t));
+               return (ba.err);
+       }
+
+       err = traverse_dataset(ds, fromtxg, TRAVERSE_PRE | TRAVERSE_PREFETCH,
+           backup_cb, &ba);
+
+       if (err) {
+               if (err == EINTR && ba.err)
+                       err = ba.err;
+               kmem_free(drr, sizeof (dmu_replay_record_t));
+               return (err);
+       }
+
+       bzero(drr, sizeof (dmu_replay_record_t));
+       drr->drr_type = DRR_END;
+       drr->drr_u.drr_end.drr_checksum = ba.zc;
+
+       if (dump_bytes(&ba, drr, sizeof (dmu_replay_record_t))) {
+               kmem_free(drr, sizeof (dmu_replay_record_t));
+               return (ba.err);
+       }
+
+       kmem_free(drr, sizeof (dmu_replay_record_t));
+
+       return (0);
+}
+
+struct recvbeginsyncarg {
+       const char *tofs;
+       const char *tosnap;
+       dsl_dataset_t *origin;
+       uint64_t fromguid;
+       dmu_objset_type_t type;
+       void *tag;
+       boolean_t force;
+       uint64_t dsflags;
+       char clonelastname[MAXNAMELEN];
+       dsl_dataset_t *ds; /* the ds to recv into; returned from the syncfunc */
+};
+
+static dsl_dataset_t *
+recv_full_sync_impl(dsl_pool_t *dp, uint64_t dsobj, dmu_objset_type_t type,
+    cred_t *cr, dmu_tx_t *tx)
+{
+       dsl_dataset_t *ds;
+
+       /* This should always work, since we just created it */
+       /* XXX - create should return an owned ds */
+       VERIFY(0 == dsl_dataset_own_obj(dp, dsobj,
+           DS_MODE_INCONSISTENT, dmu_recv_tag, &ds));
+
+       if (type != DMU_OST_NONE) {
+               (void) dmu_objset_create_impl(dp->dp_spa,
+                   ds, &ds->ds_phys->ds_bp, type, tx);
+       }
+
+       spa_history_internal_log(LOG_DS_REPLAY_FULL_SYNC,
+           dp->dp_spa, tx, cr, "dataset = %lld", dsobj);
+
+       return (ds);
+}
+
+/* ARGSUSED */
+static int
+recv_full_check(void *arg1, void *arg2, dmu_tx_t *tx)
+{
+       dsl_dir_t *dd = arg1;
+       struct recvbeginsyncarg *rbsa = arg2;
+       objset_t *mos = dd->dd_pool->dp_meta_objset;
+       uint64_t val;
+       int err;
+
+       err = zap_lookup(mos, dd->dd_phys->dd_child_dir_zapobj,
+           strrchr(rbsa->tofs, '/') + 1, sizeof (uint64_t), 1, &val);
+
+       if (err != ENOENT)
+               return (err ? err : EEXIST);
+
+       if (rbsa->origin) {
+               /* make sure it's a snap in the same pool */
+               if (rbsa->origin->ds_dir->dd_pool != dd->dd_pool)
+                       return (EXDEV);
+               if (rbsa->origin->ds_phys->ds_num_children == 0)
+                       return (EINVAL);
+               if (rbsa->origin->ds_phys->ds_guid != rbsa->fromguid)
+                       return (ENODEV);
+       }
+
+       return (0);
+}
+
+static void
+recv_full_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
+{
+       dsl_dir_t *dd = arg1;
+       struct recvbeginsyncarg *rbsa = arg2;
+       uint64_t flags = DS_FLAG_INCONSISTENT | rbsa->dsflags;
+       uint64_t dsobj;
+
+       dsobj = dsl_dataset_create_sync(dd, strrchr(rbsa->tofs, '/') + 1,
+           rbsa->origin, flags, cr, tx);
+
+       rbsa->ds = recv_full_sync_impl(dd->dd_pool, dsobj,
+           rbsa->origin ? DMU_OST_NONE : rbsa->type, cr, tx);
+}
+
+static int
+recv_full_existing_check(void *arg1, void *arg2, dmu_tx_t *tx)
+{
+       dsl_dataset_t *ds = arg1;
+       struct recvbeginsyncarg *rbsa = arg2;
+       int err;
+
+       /* must be a head ds */
+       if (ds->ds_phys->ds_next_snap_obj != 0)
+               return (EINVAL);
+
+       /* must not be a clone ds */
+       if (dsl_dir_is_clone(ds->ds_dir))
+               return (EINVAL);
+
+       err = dsl_dataset_destroy_check(ds, rbsa->tag, tx);
+       if (err)
+               return (err);
+
+       if (rbsa->origin) {
+               /* make sure it's a snap in the same pool */
+               if (rbsa->origin->ds_dir->dd_pool != ds->ds_dir->dd_pool)
+                       return (EXDEV);
+               if (rbsa->origin->ds_phys->ds_num_children == 0)
+                       return (EINVAL);
+               if (rbsa->origin->ds_phys->ds_guid != rbsa->fromguid)
+                       return (ENODEV);
+       }
+
+       return (0);
+}
+
+static void
+recv_full_existing_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
+{
+       dsl_dataset_t *ds = arg1;
+       struct recvbeginsyncarg *rbsa = arg2;
+       dsl_dir_t *dd = ds->ds_dir;
+       uint64_t flags = DS_FLAG_INCONSISTENT | rbsa->dsflags;
+       uint64_t dsobj;
+
+       /*
+        * NB: caller must provide an extra hold on the dsl_dir_t, so it
+        * won't go away when dsl_dataset_destroy_sync() closes the
+        * dataset.
+        */
+       dsl_dataset_destroy_sync(ds, rbsa->tag, cr, tx);
+
+       dsobj = dsl_dataset_create_sync_dd(dd, rbsa->origin, flags, tx);
+
+       rbsa->ds = recv_full_sync_impl(dd->dd_pool, dsobj,
+           rbsa->origin ? DMU_OST_NONE : rbsa->type, cr, tx);
+}
+
+/* ARGSUSED */
+static int
+recv_incremental_check(void *arg1, void *arg2, dmu_tx_t *tx)
+{
+       dsl_dataset_t *ds = arg1;
+       struct recvbeginsyncarg *rbsa = arg2;
+       int err;
+       uint64_t val;
+
+       /* must not have any changes since most recent snapshot */
+       if (!rbsa->force && dsl_dataset_modified_since_lastsnap(ds))
+               return (ETXTBSY);
+
+       /* must already be a snapshot of this fs */
+       if (ds->ds_phys->ds_prev_snap_obj == 0)
+               return (ENODEV);
+
+       /* most recent snapshot must match fromguid */
+       if (ds->ds_prev->ds_phys->ds_guid != rbsa->fromguid)
+               return (ENODEV);
+
+       /* temporary clone name must not exist */
+       err = zap_lookup(ds->ds_dir->dd_pool->dp_meta_objset,
+           ds->ds_dir->dd_phys->dd_child_dir_zapobj,
+           rbsa->clonelastname, 8, 1, &val);
+       if (err == 0)
+               return (EEXIST);
+       if (err != ENOENT)
+               return (err);
+
+       /* new snapshot name must not exist */
+       err = zap_lookup(ds->ds_dir->dd_pool->dp_meta_objset,
+           ds->ds_phys->ds_snapnames_zapobj, rbsa->tosnap, 8, 1, &val);
+       if (err == 0)
+               return (EEXIST);
+       if (err != ENOENT)
+               return (err);
+       return (0);
+}
+
+/* ARGSUSED */
+static void
+recv_online_incremental_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
+{
+       dsl_dataset_t *ohds = arg1;
+       struct recvbeginsyncarg *rbsa = arg2;
+       dsl_pool_t *dp = ohds->ds_dir->dd_pool;
+       dsl_dataset_t *ods, *cds;
+       uint64_t flags = DS_FLAG_INCONSISTENT | rbsa->dsflags;
+       uint64_t dsobj;
+
+       /* create the temporary clone */
+       VERIFY(0 == dsl_dataset_hold_obj(dp, ohds->ds_phys->ds_prev_snap_obj,
+           FTAG, &ods));
+       dsobj = dsl_dataset_create_sync(ohds->ds_dir,
+           rbsa->clonelastname, ods, flags, cr, tx);
+       dsl_dataset_rele(ods, FTAG);
+
+       /* open the temporary clone */
+       VERIFY(0 == dsl_dataset_own_obj(dp, dsobj,
+           DS_MODE_INCONSISTENT, dmu_recv_tag, &cds));
+
+       /* copy the refquota from the target fs to the clone */
+       if (ohds->ds_quota > 0)
+               dsl_dataset_set_quota_sync(cds, &ohds->ds_quota, cr, tx);
+
+       rbsa->ds = cds;
+
+       spa_history_internal_log(LOG_DS_REPLAY_INC_SYNC,
+           dp->dp_spa, tx, cr, "dataset = %lld", dsobj);
+}
+
+/* ARGSUSED */
+static void
+recv_offline_incremental_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
+{
+       dsl_dataset_t *ds = arg1;
+
+       dmu_buf_will_dirty(ds->ds_dbuf, tx);
+       ds->ds_phys->ds_flags |= DS_FLAG_INCONSISTENT;
+
+       spa_history_internal_log(LOG_DS_REPLAY_INC_SYNC,
+           ds->ds_dir->dd_pool->dp_spa, tx, cr, "dataset = %lld",
+           ds->ds_object);
+}
+
+/*
+ * NB: callers *MUST* call dmu_recv_stream() if dmu_recv_begin()
+ * succeeds; otherwise we will leak the holds on the datasets.
+ */
+int
+dmu_recv_begin(char *tofs, char *tosnap, struct drr_begin *drrb,
+    boolean_t force, objset_t *origin, boolean_t online, dmu_recv_cookie_t *drc)
+{
+       int err = 0;
+       boolean_t byteswap;
+       struct recvbeginsyncarg rbsa;
+       uint64_t version;
+       int flags;
+       dsl_dataset_t *ds;
+
+       if (drrb->drr_magic == DMU_BACKUP_MAGIC)
+               byteswap = FALSE;
+       else if (drrb->drr_magic == BSWAP_64(DMU_BACKUP_MAGIC))
+               byteswap = TRUE;
+       else
+               return (EINVAL);
+
+       rbsa.tofs = tofs;
+       rbsa.tosnap = tosnap;
+       rbsa.origin = origin ? origin->os->os_dsl_dataset : NULL;
+       rbsa.fromguid = drrb->drr_fromguid;
+       rbsa.type = drrb->drr_type;
+       rbsa.tag = FTAG;
+       rbsa.dsflags = 0;
+       version = drrb->drr_version;
+       flags = drrb->drr_flags;
+
+       if (byteswap) {
+               rbsa.type = BSWAP_32(rbsa.type);
+               rbsa.fromguid = BSWAP_64(rbsa.fromguid);
+               version = BSWAP_64(version);
+               flags = BSWAP_32(flags);
+       }
+
+       if (version != DMU_BACKUP_STREAM_VERSION ||
+           rbsa.type >= DMU_OST_NUMTYPES ||
+           ((flags & DRR_FLAG_CLONE) && origin == NULL))
+               return (EINVAL);
+
+       if (flags & DRR_FLAG_CI_DATA)
+               rbsa.dsflags = DS_FLAG_CI_DATASET;
+
+       bzero(drc, sizeof (dmu_recv_cookie_t));
+       drc->drc_drrb = drrb;
+       drc->drc_tosnap = tosnap;
+       drc->drc_force = force;
+
+       /*
+        * Process the begin in syncing context.
+        */
+       if (rbsa.fromguid && !(flags & DRR_FLAG_CLONE) && !online) {
+               /* offline incremental receive */
+               err = dsl_dataset_own(tofs, 0, dmu_recv_tag, &ds);
+               if (err)
+                       return (err);
+
+               /*
+                * Only do the rollback if the most recent snapshot
+                * matches the incremental source
+                */
+               if (force) {
+                       if (ds->ds_prev == NULL ||
+                           ds->ds_prev->ds_phys->ds_guid !=
+                           rbsa.fromguid) {
+                               dsl_dataset_disown(ds, dmu_recv_tag);
+                               return (ENODEV);
+                       }
+                       (void) dsl_dataset_rollback(ds, DMU_OST_NONE);
+               }
+               rbsa.force = B_FALSE;
+               err = dsl_sync_task_do(ds->ds_dir->dd_pool,
+                   recv_incremental_check,
+                   recv_offline_incremental_sync, ds, &rbsa, 1);
+               if (err) {
+                       dsl_dataset_disown(ds, dmu_recv_tag);
+                       return (err);
+               }
+               drc->drc_logical_ds = drc->drc_real_ds = ds;
+       } else if (rbsa.fromguid && !(flags & DRR_FLAG_CLONE)) {
+               /* online incremental receive */
+
+               /* tmp clone name is: tofs/%tosnap" */
+               (void) snprintf(rbsa.clonelastname, sizeof (rbsa.clonelastname),
+                   "%%%s", tosnap);
+
+               /* open the dataset we are logically receiving into */
+               err = dsl_dataset_hold(tofs, dmu_recv_tag, &ds);
+               if (err)
+                       return (err);
+
+               rbsa.force = force;
+               err = dsl_sync_task_do(ds->ds_dir->dd_pool,
+                   recv_incremental_check,
+                   recv_online_incremental_sync, ds, &rbsa, 5);
+               if (err) {
+                       dsl_dataset_rele(ds, dmu_recv_tag);
+                       return (err);
+               }
+               drc->drc_logical_ds = ds;
+               drc->drc_real_ds = rbsa.ds;
+       } else {
+               /* create new fs -- full backup or clone */
+               dsl_dir_t *dd = NULL;
+               const char *tail;
+
+               err = dsl_dir_open(tofs, FTAG, &dd, &tail);
+               if (err)
+                       return (err);
+               if (tail == NULL) {
+                       if (!force) {
+                               dsl_dir_close(dd, FTAG);
+                               return (EEXIST);
+                       }
+
+                       rw_enter(&dd->dd_pool->dp_config_rwlock, RW_READER);
+                       err = dsl_dataset_own_obj(dd->dd_pool,
+                           dd->dd_phys->dd_head_dataset_obj,
+                           DS_MODE_INCONSISTENT, FTAG, &ds);
+                       rw_exit(&dd->dd_pool->dp_config_rwlock);
+                       if (err) {
+                               dsl_dir_close(dd, FTAG);
+                               return (err);
+                       }
+
+                       dsl_dataset_make_exclusive(ds, FTAG);
+                       err = dsl_sync_task_do(dd->dd_pool,
+                           recv_full_existing_check,
+                           recv_full_existing_sync, ds, &rbsa, 5);
+                       dsl_dataset_disown(ds, FTAG);
+               } else {
+                       err = dsl_sync_task_do(dd->dd_pool, recv_full_check,
+                           recv_full_sync, dd, &rbsa, 5);
+               }
+               dsl_dir_close(dd, FTAG);
+               if (err)
+                       return (err);
+               drc->drc_logical_ds = drc->drc_real_ds = rbsa.ds;
+               drc->drc_newfs = B_TRUE;
+       }
+
+       return (0);
+}
+
+struct restorearg {
+       int err;
+       int byteswap;
+       vnode_t *vp;
+       char *buf;
+       uint64_t voff;
+       int bufsize; /* amount of memory allocated for buf */
+       zio_cksum_t cksum;
+};
+
+static void *
+restore_read(struct restorearg *ra, int len)
+{
+       void *rv;
+       int done = 0;
+
+       /* some things will require 8-byte alignment, so everything must */
+       ASSERT3U(len % 8, ==, 0);
+
+       while (done < len) {
+               ssize_t resid;
+
+               ra->err = vn_rdwr(UIO_READ, ra->vp,
+                   (caddr_t)ra->buf + done, len - done,
+                   ra->voff, UIO_SYSSPACE, FAPPEND,
+                   RLIM64_INFINITY, CRED(), &resid);
+
+               if (resid == len - done)
+                       ra->err = EINVAL;
+               ra->voff += len - done - resid;
+               done = len - resid;
+               if (ra->err)
+                       return (NULL);
+       }
+
+       ASSERT3U(done, ==, len);
+       rv = ra->buf;
+       if (ra->byteswap)
+               fletcher_4_incremental_byteswap(rv, len, &ra->cksum);
+       else
+               fletcher_4_incremental_native(rv, len, &ra->cksum);
+       return (rv);
+}
+
+static void
+backup_byteswap(dmu_replay_record_t *drr)
+{
+#define        DO64(X) (drr->drr_u.X = BSWAP_64(drr->drr_u.X))
+#define        DO32(X) (drr->drr_u.X = BSWAP_32(drr->drr_u.X))
+       drr->drr_type = BSWAP_32(drr->drr_type);
+       drr->drr_payloadlen = BSWAP_32(drr->drr_payloadlen);
+       switch (drr->drr_type) {
+       case DRR_BEGIN:
+               DO64(drr_begin.drr_magic);
+               DO64(drr_begin.drr_version);
+               DO64(drr_begin.drr_creation_time);
+               DO32(drr_begin.drr_type);
+               DO32(drr_begin.drr_flags);
+               DO64(drr_begin.drr_toguid);
+               DO64(drr_begin.drr_fromguid);
+               break;
+       case DRR_OBJECT:
+               DO64(drr_object.drr_object);
+               /* DO64(drr_object.drr_allocation_txg); */
+               DO32(drr_object.drr_type);
+               DO32(drr_object.drr_bonustype);
+               DO32(drr_object.drr_blksz);
+               DO32(drr_object.drr_bonuslen);
+               break;
+       case DRR_FREEOBJECTS:
+               DO64(drr_freeobjects.drr_firstobj);
+               DO64(drr_freeobjects.drr_numobjs);
+               break;
+       case DRR_WRITE:
+               DO64(drr_write.drr_object);
+               DO32(drr_write.drr_type);
+               DO64(drr_write.drr_offset);
+               DO64(drr_write.drr_length);
+               break;
+       case DRR_FREE:
+               DO64(drr_free.drr_object);
+               DO64(drr_free.drr_offset);
+               DO64(drr_free.drr_length);
+               break;
+       case DRR_END:
+               DO64(drr_end.drr_checksum.zc_word[0]);
+               DO64(drr_end.drr_checksum.zc_word[1]);
+               DO64(drr_end.drr_checksum.zc_word[2]);
+               DO64(drr_end.drr_checksum.zc_word[3]);
+               break;
+       }
+#undef DO64
+#undef DO32
+}
+
+static int
+restore_object(struct restorearg *ra, objset_t *os, struct drr_object *drro)
+{
+       int err;
+       dmu_tx_t *tx;
+       void *data = NULL;
+
+       err = dmu_object_info(os, drro->drr_object, NULL);
+
+       if (err != 0 && err != ENOENT)
+               return (EINVAL);
+
+       if (drro->drr_type == DMU_OT_NONE ||
+           drro->drr_type >= DMU_OT_NUMTYPES ||
+           drro->drr_bonustype >= DMU_OT_NUMTYPES ||
+           drro->drr_checksum >= ZIO_CHECKSUM_FUNCTIONS ||
+           drro->drr_compress >= ZIO_COMPRESS_FUNCTIONS ||
+           P2PHASE(drro->drr_blksz, SPA_MINBLOCKSIZE) ||
+           drro->drr_blksz < SPA_MINBLOCKSIZE ||
+           drro->drr_blksz > SPA_MAXBLOCKSIZE ||
+           drro->drr_bonuslen > DN_MAX_BONUSLEN) {
+               return (EINVAL);
+       }
+
+       if (drro->drr_bonuslen) {
+               data = restore_read(ra, P2ROUNDUP(drro->drr_bonuslen, 8));
+               if (ra->err)
+                       return (ra->err);
+       }
+
+       tx = dmu_tx_create(os);
+
+       if (err == ENOENT) {
+               /* currently free, want to be allocated */
+               dmu_tx_hold_bonus(tx, DMU_NEW_OBJECT);
+               dmu_tx_hold_write(tx, DMU_NEW_OBJECT, 0, 1);
+               err = dmu_tx_assign(tx, TXG_WAIT);
+               if (err) {
+                       dmu_tx_abort(tx);
+                       return (err);
+               }
+               err = dmu_object_claim(os, drro->drr_object,
+                   drro->drr_type, drro->drr_blksz,
+                   drro->drr_bonustype, drro->drr_bonuslen, tx);
+       } else {
+               /* currently allocated, want to be allocated */
+               dmu_tx_hold_bonus(tx, drro->drr_object);
+               /*
+                * We may change blocksize, so need to
+                * hold_write
+                */
+               dmu_tx_hold_write(tx, drro->drr_object, 0, 1);
+               err = dmu_tx_assign(tx, TXG_WAIT);
+               if (err) {
+                       dmu_tx_abort(tx);
+                       return (err);
+               }
+
+               err = dmu_object_reclaim(os, drro->drr_object,
+                   drro->drr_type, drro->drr_blksz,
+                   drro->drr_bonustype, drro->drr_bonuslen, tx);
+       }
+       if (err) {
+               dmu_tx_commit(tx);
+               return (EINVAL);
+       }
+
+       dmu_object_set_checksum(os, drro->drr_object, drro->drr_checksum, tx);
+       dmu_object_set_compress(os, drro->drr_object, drro->drr_compress, tx);
+
+       if (data != NULL) {
+               dmu_buf_t *db;
+
+               VERIFY(0 == dmu_bonus_hold(os, drro->drr_object, FTAG, &db));
+               dmu_buf_will_dirty(db, tx);
+
+               ASSERT3U(db->db_size, >=, drro->drr_bonuslen);
+               bcopy(data, db->db_data, drro->drr_bonuslen);
+               if (ra->byteswap) {
+                       dmu_ot[drro->drr_bonustype].ot_byteswap(db->db_data,
+                           drro->drr_bonuslen);
+               }
+               dmu_buf_rele(db, FTAG);
+       }
+       dmu_tx_commit(tx);
+       return (0);
+}
+
+/* ARGSUSED */
+static int
+restore_freeobjects(struct restorearg *ra, objset_t *os,
+    struct drr_freeobjects *drrfo)
+{
+       uint64_t obj;
+
+       if (drrfo->drr_firstobj + drrfo->drr_numobjs < drrfo->drr_firstobj)
+               return (EINVAL);
+
+       for (obj = drrfo->drr_firstobj;
+           obj < drrfo->drr_firstobj + drrfo->drr_numobjs;
+           (void) dmu_object_next(os, &obj, FALSE, 0)) {
+               int err;
+
+               if (dmu_object_info(os, obj, NULL) != 0)
+                       continue;
+
+               err = dmu_free_object(os, obj);
+               if (err)
+                       return (err);
+       }
+       return (0);
+}
+
+static int
+restore_write(struct restorearg *ra, objset_t *os,
+    struct drr_write *drrw)
+{
+       dmu_tx_t *tx;
+       void *data;
+       int err;
+
+       if (drrw->drr_offset + drrw->drr_length < drrw->drr_offset ||
+           drrw->drr_type >= DMU_OT_NUMTYPES)
+               return (EINVAL);
+
+       data = restore_read(ra, drrw->drr_length);
+       if (data == NULL)
+               return (ra->err);
+
+       if (dmu_object_info(os, drrw->drr_object, NULL) != 0)
+               return (EINVAL);
+
+       tx = dmu_tx_create(os);
+
+       dmu_tx_hold_write(tx, drrw->drr_object,
+           drrw->drr_offset, drrw->drr_length);
+       err = dmu_tx_assign(tx, TXG_WAIT);
+       if (err) {
+               dmu_tx_abort(tx);
+               return (err);
+       }
+       if (ra->byteswap)
+               dmu_ot[drrw->drr_type].ot_byteswap(data, drrw->drr_length);
+       dmu_write(os, drrw->drr_object,
+           drrw->drr_offset, drrw->drr_length, data, tx);
+       dmu_tx_commit(tx);
+       return (0);
+}
+
+/* ARGSUSED */
+static int
+restore_free(struct restorearg *ra, objset_t *os,
+    struct drr_free *drrf)
+{
+       int err;
+
+       if (drrf->drr_length != -1ULL &&
+           drrf->drr_offset + drrf->drr_length < drrf->drr_offset)
+               return (EINVAL);
+
+       if (dmu_object_info(os, drrf->drr_object, NULL) != 0)
+               return (EINVAL);
+
+       err = dmu_free_long_range(os, drrf->drr_object,
+           drrf->drr_offset, drrf->drr_length);
+       return (err);
+}
+
+void
+dmu_recv_abort_cleanup(dmu_recv_cookie_t *drc)
+{
+       if (drc->drc_newfs || drc->drc_real_ds != drc->drc_logical_ds) {
+               /*
+                * online incremental or new fs: destroy the fs (which
+                * may be a clone) that we created
+                */
+               (void) dsl_dataset_destroy(drc->drc_real_ds, dmu_recv_tag);
+               if (drc->drc_real_ds != drc->drc_logical_ds)
+                       dsl_dataset_rele(drc->drc_logical_ds, dmu_recv_tag);
+       } else {
+               /*
+                * offline incremental: rollback to most recent snapshot.
+                */
+               (void) dsl_dataset_rollback(drc->drc_real_ds, DMU_OST_NONE);
+               dsl_dataset_disown(drc->drc_real_ds, dmu_recv_tag);
+       }
+}
+
+/*
+ * NB: callers *must* call dmu_recv_end() if this succeeds.
+ */
+int
+dmu_recv_stream(dmu_recv_cookie_t *drc, vnode_t *vp, offset_t *voffp)
+{
+       struct restorearg ra = { 0 };
+       dmu_replay_record_t *drr;
+       objset_t *os;
+       zio_cksum_t pcksum;
+
+       if (drc->drc_drrb->drr_magic == BSWAP_64(DMU_BACKUP_MAGIC))
+               ra.byteswap = TRUE;
+
+       {
+               /* compute checksum of drr_begin record */
+               dmu_replay_record_t *drr;
+               drr = kmem_zalloc(sizeof (dmu_replay_record_t), KM_SLEEP);
+
+               drr->drr_type = DRR_BEGIN;
+               drr->drr_u.drr_begin = *drc->drc_drrb;
+               if (ra.byteswap) {
+                       fletcher_4_incremental_byteswap(drr,
+                           sizeof (dmu_replay_record_t), &ra.cksum);
+               } else {
+                       fletcher_4_incremental_native(drr,
+                           sizeof (dmu_replay_record_t), &ra.cksum);
+               }
+               kmem_free(drr, sizeof (dmu_replay_record_t));
+       }
+
+       if (ra.byteswap) {
+               struct drr_begin *drrb = drc->drc_drrb;
+               drrb->drr_magic = BSWAP_64(drrb->drr_magic);
+               drrb->drr_version = BSWAP_64(drrb->drr_version);
+               drrb->drr_creation_time = BSWAP_64(drrb->drr_creation_time);
+               drrb->drr_type = BSWAP_32(drrb->drr_type);
+               drrb->drr_toguid = BSWAP_64(drrb->drr_toguid);
+               drrb->drr_fromguid = BSWAP_64(drrb->drr_fromguid);
+       }
+
+       ra.vp = vp;
+       ra.voff = *voffp;
+       ra.bufsize = 1<<20;
+       ra.buf = kmem_alloc(ra.bufsize, KM_SLEEP);
+
+       /* these were verified in dmu_recv_begin */
+       ASSERT(drc->drc_drrb->drr_version == DMU_BACKUP_STREAM_VERSION);
+       ASSERT(drc->drc_drrb->drr_type < DMU_OST_NUMTYPES);
+
+       /*
+        * Open the objset we are modifying.
+        */
+       VERIFY(dmu_objset_open_ds(drc->drc_real_ds, DMU_OST_ANY, &os) == 0);
+
+       ASSERT(drc->drc_real_ds->ds_phys->ds_flags & DS_FLAG_INCONSISTENT);
+
+       /*
+        * Read records and process them.
+        */
+       pcksum = ra.cksum;
+       while (ra.err == 0 &&
+           NULL != (drr = restore_read(&ra, sizeof (*drr)))) {
+               if (issig(JUSTLOOKING) && issig(FORREAL)) {
+                       ra.err = EINTR;
+                       goto out;
+               }
+
+               if (ra.byteswap)
+                       backup_byteswap(drr);
+
+               switch (drr->drr_type) {
+               case DRR_OBJECT:
+               {
+                       /*
+                        * We need to make a copy of the record header,
+                        * because restore_{object,write} may need to
+                        * restore_read(), which will invalidate drr.
+                        */
+                       struct drr_object drro = drr->drr_u.drr_object;
+                       ra.err = restore_object(&ra, os, &drro);
+                       break;
+               }
+               case DRR_FREEOBJECTS:
+               {
+                       struct drr_freeobjects drrfo =
+                           drr->drr_u.drr_freeobjects;
+                       ra.err = restore_freeobjects(&ra, os, &drrfo);
+                       break;
+               }
+               case DRR_WRITE:
+               {
+                       struct drr_write drrw = drr->drr_u.drr_write;
+                       ra.err = restore_write(&ra, os, &drrw);
+                       break;
+               }
+               case DRR_FREE:
+               {
+                       struct drr_free drrf = drr->drr_u.drr_free;
+                       ra.err = restore_free(&ra, os, &drrf);
+                       break;
+               }
+               case DRR_END:
+               {
+                       struct drr_end drre = drr->drr_u.drr_end;
+                       /*
+                        * We compare against the *previous* checksum
+                        * value, because the stored checksum is of
+                        * everything before the DRR_END record.
+                        */
+                       if (!ZIO_CHECKSUM_EQUAL(drre.drr_checksum, pcksum))
+                               ra.err = ECKSUM;
+                       goto out;
+               }
+               default:
+                       ra.err = EINVAL;
+                       goto out;
+               }
+               pcksum = ra.cksum;
+       }
+       ASSERT(ra.err != 0);
+
+out:
+       dmu_objset_close(os);
+
+       if (ra.err != 0) {
+               /*
+                * rollback or destroy what we created, so we don't
+                * leave it in the restoring state.
+                */
+               txg_wait_synced(drc->drc_real_ds->ds_dir->dd_pool, 0);
+               dmu_recv_abort_cleanup(drc);
+       }
+
+       kmem_free(ra.buf, ra.bufsize);
+       *voffp = ra.voff;
+       return (ra.err);
+}
+
+struct recvendsyncarg {
+       char *tosnap;
+       uint64_t creation_time;
+       uint64_t toguid;
+};
+
+static int
+recv_end_check(void *arg1, void *arg2, dmu_tx_t *tx)
+{
+       dsl_dataset_t *ds = arg1;
+       struct recvendsyncarg *resa = arg2;
+
+       return (dsl_dataset_snapshot_check(ds, resa->tosnap, tx));
+}
+
+static void
+recv_end_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
+{
+       dsl_dataset_t *ds = arg1;
+       struct recvendsyncarg *resa = arg2;
+
+       dsl_dataset_snapshot_sync(ds, resa->tosnap, cr, tx);
+
+       /* set snapshot's creation time and guid */
+       dmu_buf_will_dirty(ds->ds_prev->ds_dbuf, tx);
+       ds->ds_prev->ds_phys->ds_creation_time = resa->creation_time;
+       ds->ds_prev->ds_phys->ds_guid = resa->toguid;
+       ds->ds_prev->ds_phys->ds_flags &= ~DS_FLAG_INCONSISTENT;
+
+       dmu_buf_will_dirty(ds->ds_dbuf, tx);
+       ds->ds_phys->ds_flags &= ~DS_FLAG_INCONSISTENT;
+}
+
+int
+dmu_recv_end(dmu_recv_cookie_t *drc)
+{
+       struct recvendsyncarg resa;
+       dsl_dataset_t *ds = drc->drc_logical_ds;
+       int err;
+
+       /*
+        * XXX hack; seems the ds is still dirty and
+        * dsl_pool_zil_clean() expects it to have a ds_user_ptr
+        * (and zil), but clone_swap() can close it.
+        */
+       txg_wait_synced(ds->ds_dir->dd_pool, 0);
+
+       if (ds != drc->drc_real_ds) {
+               /* we are doing an online recv */
+               if (dsl_dataset_tryown(ds, FALSE, dmu_recv_tag)) {
+                       err = dsl_dataset_clone_swap(drc->drc_real_ds, ds,
+                           drc->drc_force);
+                       if (err)
+                               dsl_dataset_disown(ds, dmu_recv_tag);
+               } else {
+                       err = EBUSY;
+                       dsl_dataset_rele(ds, dmu_recv_tag);
+               }
+               /* dsl_dataset_destroy() will disown the ds */
+               (void) dsl_dataset_destroy(drc->drc_real_ds, dmu_recv_tag);
+               if (err)
+                       return (err);
+       }
+
+       resa.creation_time = drc->drc_drrb->drr_creation_time;
+       resa.toguid = drc->drc_drrb->drr_toguid;
+       resa.tosnap = drc->drc_tosnap;
+
+       err = dsl_sync_task_do(ds->ds_dir->dd_pool,
+           recv_end_check, recv_end_sync, ds, &resa, 3);
+       if (err) {
+               if (drc->drc_newfs) {
+                       ASSERT(ds == drc->drc_real_ds);
+                       (void) dsl_dataset_destroy(ds, dmu_recv_tag);
+                       return (err);
+               } else {
+                       (void) dsl_dataset_rollback(ds, DMU_OST_NONE);
+               }
+       }
+
+       /* release the hold from dmu_recv_begin */
+       dsl_dataset_disown(ds, dmu_recv_tag);
+       return (err);
+}