dmu_send.c

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/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
 * Copyright (c) 2012 by Delphix. All rights reserved.
 * Copyright (c) 2012, Joyent, Inc. All rights reserved.
 * Copyright (c) 2012, Martin Matuska <mm@FreeBSD.org>. All rights reserved.
 */

#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_prop.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>
#include <sys/zfs_znode.h>
#include <zfs_fletcher.h>
#include <sys/avl.h>
#include <sys/ddt.h>
#include <sys/zfs_onexit.h>

/* Set this tunable to TRUE to replace corrupt data with 0x2f5baddb10c */
int zfs_send_corrupt_data = B_FALSE;

static char *dmu_recv_tag = "dmu_recv_tag";

static int
dump_bytes(dmu_sendarg_t *dsp, void *buf, int len)
{
        dsl_dataset_t *ds = dsp->dsa_os->os_dsl_dataset;
        struct uio auio;
        struct iovec aiov;
        ASSERT0(len % 8);

        fletcher_4_incremental_native(buf, len, &dsp->dsa_zc);
        aiov.iov_base = buf;
        aiov.iov_len = len;
        auio.uio_iov = &aiov;
        auio.uio_iovcnt = 1;
        auio.uio_resid = len;
        auio.uio_segflg = UIO_SYSSPACE;
        auio.uio_rw = UIO_WRITE;
        auio.uio_offset = (off_t)-1;
        auio.uio_td = dsp->dsa_td;
#ifdef _KERNEL
        if (dsp->dsa_fp->f_type == DTYPE_VNODE)
                bwillwrite();
        dsp->dsa_err = fo_write(dsp->dsa_fp, &auio, dsp->dsa_td->td_ucred, 0,
            dsp->dsa_td);
#else
        fprintf(stderr, "%s: returning EOPNOTSUPP\n", __func__);
        dsp->dsa_err = EOPNOTSUPP;
#endif
        mutex_enter(&ds->ds_sendstream_lock);
        *dsp->dsa_off += len;
        mutex_exit(&ds->ds_sendstream_lock);

        return (dsp->dsa_err);
}

static int
dump_free(dmu_sendarg_t *dsp, uint64_t object, uint64_t offset,
    uint64_t length)
{
        struct drr_free *drrf = &(dsp->dsa_drr->drr_u.drr_free);

        if (length != -1ULL && offset + length < offset)
                length = -1ULL;

        /*
         * If there is a pending op, but it's not PENDING_FREE, push it out,
         * since free block aggregation can only be done for blocks of the
         * same type (i.e., DRR_FREE records can only be aggregated with
         * other DRR_FREE records.  DRR_FREEOBJECTS records can only be
         * aggregated with other DRR_FREEOBJECTS records.
         */
        if (dsp->dsa_pending_op != PENDING_NONE &&
            dsp->dsa_pending_op != PENDING_FREE) {
                if (dump_bytes(dsp, dsp->dsa_drr,
                    sizeof (dmu_replay_record_t)) != 0)
                        return (EINTR);
                dsp->dsa_pending_op = PENDING_NONE;
        }

        if (dsp->dsa_pending_op == PENDING_FREE) {
                /*
                 * There should never be a PENDING_FREE if length is -1
                 * (because dump_dnode is the only place where this
                 * function is called with a -1, and only after flushing
                 * any pending record).
                 */
                ASSERT(length != -1ULL);
                /*
                 * Check to see whether this free block can be aggregated
                 * with pending one.
                 */
                if (drrf->drr_object == object && drrf->drr_offset +
                    drrf->drr_length == offset) {
                        drrf->drr_length += length;
                        return (0);
                } else {
                        /* not a continuation.  Push out pending record */
                        if (dump_bytes(dsp, dsp->dsa_drr,
                            sizeof (dmu_replay_record_t)) != 0)
                                return (EINTR);
                        dsp->dsa_pending_op = PENDING_NONE;
                }
        }
        /* create a FREE record and make it pending */
        bzero(dsp->dsa_drr, sizeof (dmu_replay_record_t));
        dsp->dsa_drr->drr_type = DRR_FREE;
        drrf->drr_object = object;
        drrf->drr_offset = offset;
        drrf->drr_length = length;
        drrf->drr_toguid = dsp->dsa_toguid;
        if (length == -1ULL) {
                if (dump_bytes(dsp, dsp->dsa_drr,
                    sizeof (dmu_replay_record_t)) != 0)
                        return (EINTR);
        } else {
                dsp->dsa_pending_op = PENDING_FREE;
        }

        return (0);
}

static int
dump_data(dmu_sendarg_t *dsp, dmu_object_type_t type,
    uint64_t object, uint64_t offset, int blksz, const blkptr_t *bp, void *data)
{
        struct drr_write *drrw = &(dsp->dsa_drr->drr_u.drr_write);


        /*
         * If there is any kind of pending aggregation (currently either
         * a grouping of free objects or free blocks), push it out to
         * the stream, since aggregation can't be done across operations
         * of different types.
         */
        if (dsp->dsa_pending_op != PENDING_NONE) {
                if (dump_bytes(dsp, dsp->dsa_drr,
                    sizeof (dmu_replay_record_t)) != 0)
                        return (EINTR);
                dsp->dsa_pending_op = PENDING_NONE;
        }
        /* write a DATA record */
        bzero(dsp->dsa_drr, sizeof (dmu_replay_record_t));
        dsp->dsa_drr->drr_type = DRR_WRITE;
        drrw->drr_object = object;
        drrw->drr_type = type;
        drrw->drr_offset = offset;
        drrw->drr_length = blksz;
        drrw->drr_toguid = dsp->dsa_toguid;
        drrw->drr_checksumtype = BP_GET_CHECKSUM(bp);
        if (zio_checksum_table[drrw->drr_checksumtype].ci_dedup)
                drrw->drr_checksumflags |= DRR_CHECKSUM_DEDUP;
        DDK_SET_LSIZE(&drrw->drr_key, BP_GET_LSIZE(bp));
        DDK_SET_PSIZE(&drrw->drr_key, BP_GET_PSIZE(bp));
        DDK_SET_COMPRESS(&drrw->drr_key, BP_GET_COMPRESS(bp));
        drrw->drr_key.ddk_cksum = bp->blk_cksum;

        if (dump_bytes(dsp, dsp->dsa_drr, sizeof (dmu_replay_record_t)) != 0)
                return (EINTR);
        if (dump_bytes(dsp, data, blksz) != 0)
                return (EINTR);
        return (0);
}

static int
dump_spill(dmu_sendarg_t *dsp, uint64_t object, int blksz, void *data)
{
        struct drr_spill *drrs = &(dsp->dsa_drr->drr_u.drr_spill);

        if (dsp->dsa_pending_op != PENDING_NONE) {
                if (dump_bytes(dsp, dsp->dsa_drr,
                    sizeof (dmu_replay_record_t)) != 0)
                        return (EINTR);
                dsp->dsa_pending_op = PENDING_NONE;
        }

        /* write a SPILL record */
        bzero(dsp->dsa_drr, sizeof (dmu_replay_record_t));
        dsp->dsa_drr->drr_type = DRR_SPILL;
        drrs->drr_object = object;
        drrs->drr_length = blksz;
        drrs->drr_toguid = dsp->dsa_toguid;

        if (dump_bytes(dsp, dsp->dsa_drr, sizeof (dmu_replay_record_t)))
                return (EINTR);
        if (dump_bytes(dsp, data, blksz))
                return (EINTR);
        return (0);
}

static int
dump_freeobjects(dmu_sendarg_t *dsp, uint64_t firstobj, uint64_t numobjs)
{
        struct drr_freeobjects *drrfo = &(dsp->dsa_drr->drr_u.drr_freeobjects);

        /*
         * If there is a pending op, but it's not PENDING_FREEOBJECTS,
         * push it out, since free block aggregation can only be done for
         * blocks of the same type (i.e., DRR_FREE records can only be
         * aggregated with other DRR_FREE records.  DRR_FREEOBJECTS records
         * can only be aggregated with other DRR_FREEOBJECTS records.
         */
        if (dsp->dsa_pending_op != PENDING_NONE &&
            dsp->dsa_pending_op != PENDING_FREEOBJECTS) {
                if (dump_bytes(dsp, dsp->dsa_drr,
                    sizeof (dmu_replay_record_t)) != 0)
                        return (EINTR);
                dsp->dsa_pending_op = PENDING_NONE;
        }
        if (dsp->dsa_pending_op == PENDING_FREEOBJECTS) {
                /*
                 * See whether this free object array can be aggregated
                 * with pending one
                 */
                if (drrfo->drr_firstobj + drrfo->drr_numobjs == firstobj) {
                        drrfo->drr_numobjs += numobjs;
                        return (0);
                } else {
                        /* can't be aggregated.  Push out pending record */
                        if (dump_bytes(dsp, dsp->dsa_drr,
                            sizeof (dmu_replay_record_t)) != 0)
                                return (EINTR);
                        dsp->dsa_pending_op = PENDING_NONE;
                }
        }

        /* write a FREEOBJECTS record */
        bzero(dsp->dsa_drr, sizeof (dmu_replay_record_t));
        dsp->dsa_drr->drr_type = DRR_FREEOBJECTS;
        drrfo->drr_firstobj = firstobj;
        drrfo->drr_numobjs = numobjs;
        drrfo->drr_toguid = dsp->dsa_toguid;

        dsp->dsa_pending_op = PENDING_FREEOBJECTS;

        return (0);
}

static int
dump_dnode(dmu_sendarg_t *dsp, uint64_t object, dnode_phys_t *dnp)
{
        struct drr_object *drro = &(dsp->dsa_drr->drr_u.drr_object);

        if (dnp == NULL || dnp->dn_type == DMU_OT_NONE)
                return (dump_freeobjects(dsp, object, 1));

        if (dsp->dsa_pending_op != PENDING_NONE) {
                if (dump_bytes(dsp, dsp->dsa_drr,
                    sizeof (dmu_replay_record_t)) != 0)
                        return (EINTR);
                dsp->dsa_pending_op = PENDING_NONE;
        }

        /* write an OBJECT record */
        bzero(dsp->dsa_drr, sizeof (dmu_replay_record_t));
        dsp->dsa_drr->drr_type = DRR_OBJECT;
        drro->drr_object = object;
        drro->drr_type = dnp->dn_type;
        drro->drr_bonustype = dnp->dn_bonustype;
        drro->drr_blksz = dnp->dn_datablkszsec << SPA_MINBLOCKSHIFT;
        drro->drr_bonuslen = dnp->dn_bonuslen;
        drro->drr_checksumtype = dnp->dn_checksum;
        drro->drr_compress = dnp->dn_compress;
        drro->drr_toguid = dsp->dsa_toguid;

        if (dump_bytes(dsp, dsp->dsa_drr, sizeof (dmu_replay_record_t)) != 0)
                return (EINTR);

        if (dump_bytes(dsp, DN_BONUS(dnp), P2ROUNDUP(dnp->dn_bonuslen, 8)) != 0)
                return (EINTR);

        /* free anything past the end of the file */
        if (dump_free(dsp, object, (dnp->dn_maxblkid + 1) *
            (dnp->dn_datablkszsec << SPA_MINBLOCKSHIFT), -1ULL))
                return (EINTR);
        if (dsp->dsa_err)
                return (EINTR);
        return (0);
}

#define BP_SPAN(dnp, level) \
        (((uint64_t)dnp->dn_datablkszsec) << (SPA_MINBLOCKSHIFT + \
        (level) * (dnp->dn_indblkshift - SPA_BLKPTRSHIFT)))

/* ARGSUSED */
static int
backup_cb(spa_t *spa, zilog_t *zilog, const blkptr_t *bp, arc_buf_t *pbuf,
    const zbookmark_t *zb, const dnode_phys_t *dnp, void *arg)
{
        dmu_sendarg_t *dsp = 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 (zb->zb_object != DMU_META_DNODE_OBJECT &&
            DMU_OBJECT_IS_SPECIAL(zb->zb_object)) {
                return (0);
        } else if (bp == NULL && zb->zb_object == DMU_META_DNODE_OBJECT) {
                uint64_t span = BP_SPAN(dnp, zb->zb_level);
                uint64_t dnobj = (zb->zb_blkid * span) >> DNODE_SHIFT;
                err = dump_freeobjects(dsp, dnobj, span >> DNODE_SHIFT);
        } else if (bp == NULL) {
                uint64_t span = BP_SPAN(dnp, zb->zb_level);
                err = dump_free(dsp, 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 (dsl_read(NULL, spa, bp, pbuf,
                    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(dsp, dnobj, blk+i);
                        if (err)
                                break;
                }
                (void) arc_buf_remove_ref(abuf, &abuf);
        } else if (type == DMU_OT_SA) {
                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_spill(dsp, zb->zb_object, blksz, abuf->b_data);
                (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 (dsl_read(NULL, spa, bp, pbuf,
                    arc_getbuf_func, &abuf, ZIO_PRIORITY_ASYNC_READ,
                    ZIO_FLAG_CANFAIL, &aflags, zb) != 0) {
                        if (zfs_send_corrupt_data) {
                                /* Send a block filled with 0x"zfs badd bloc" */
                                abuf = arc_buf_alloc(spa, blksz, &abuf,
                                    ARC_BUFC_DATA);
                                uint64_t *ptr;
                                for (ptr = abuf->b_data;
                                    (char *)ptr < (char *)abuf->b_data + blksz;
                                    ptr++)
                                        *ptr = 0x2f5baddb10c;
                        } else {
                                return (EIO);
                        }
                }

                err = dump_data(dsp, type, zb->zb_object, zb->zb_blkid * blksz,
                    blksz, bp, abuf->b_data);
                (void) arc_buf_remove_ref(abuf, &abuf);
        }

        ASSERT(err == 0 || err == EINTR);
        return (err);
}

int
dmu_send(objset_t *tosnap, objset_t *fromsnap, boolean_t fromorigin,
    int outfd, struct file *fp, offset_t *off)
{
        dsl_dataset_t *ds = tosnap->os_dsl_dataset;
        dsl_dataset_t *fromds = fromsnap ? fromsnap->os_dsl_dataset : NULL;
        dmu_replay_record_t *drr;
        dmu_sendarg_t *dsp;
        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;
        DMU_SET_STREAM_HDRTYPE(drr->drr_u.drr_begin.drr_versioninfo,
            DMU_SUBSTREAM);

#ifdef _KERNEL
        if (dmu_objset_type(tosnap) == DMU_OST_ZFS) {
                uint64_t version;
                if (zfs_get_zplprop(tosnap, ZFS_PROP_VERSION, &version) != 0) {
                        kmem_free(drr, sizeof (dmu_replay_record_t));
                        return (EINVAL);
                }
                if (version == ZPL_VERSION_SA) {
                        DMU_SET_FEATUREFLAGS(
                            drr->drr_u.drr_begin.drr_versioninfo,
                            DMU_BACKUP_FEATURE_SA_SPILL);
                }
        }
#endif

        drr->drr_u.drr_begin.drr_creation_time =
            ds->ds_phys->ds_creation_time;
        drr->drr_u.drr_begin.drr_type = tosnap->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);

        dsp = kmem_zalloc(sizeof (dmu_sendarg_t), KM_SLEEP);

        dsp->dsa_drr = drr;
        dsp->dsa_outfd = outfd;
        dsp->dsa_proc = curproc;
        dsp->dsa_td = curthread;
        dsp->dsa_fp = fp;
        dsp->dsa_os = tosnap;
        dsp->dsa_off = off;
        dsp->dsa_toguid = ds->ds_phys->ds_guid;
        ZIO_SET_CHECKSUM(&dsp->dsa_zc, 0, 0, 0, 0);
        dsp->dsa_pending_op = PENDING_NONE;

        mutex_enter(&ds->ds_sendstream_lock);
        list_insert_head(&ds->ds_sendstreams, dsp);
        mutex_exit(&ds->ds_sendstream_lock);

        if (dump_bytes(dsp, drr, sizeof (dmu_replay_record_t)) != 0) {
                err = dsp->dsa_err;
                goto out;
        }

        err = traverse_dataset(ds, fromtxg, TRAVERSE_PRE | TRAVERSE_PREFETCH,
            backup_cb, dsp);

        if (dsp->dsa_pending_op != PENDING_NONE)
                if (dump_bytes(dsp, drr, sizeof (dmu_replay_record_t)) != 0)
                        err = EINTR;

        if (err) {
                if (err == EINTR && dsp->dsa_err)
                        err = dsp->dsa_err;
                goto out;
        }

        bzero(drr, sizeof (dmu_replay_record_t));
        drr->drr_type = DRR_END;
        drr->drr_u.drr_end.drr_checksum = dsp->dsa_zc;
        drr->drr_u.drr_end.drr_toguid = dsp->dsa_toguid;

        if (dump_bytes(dsp, drr, sizeof (dmu_replay_record_t)) != 0) {
                err = dsp->dsa_err;
                goto out;
        }

out:
        mutex_enter(&ds->ds_sendstream_lock);
        list_remove(&ds->ds_sendstreams, dsp);
        mutex_exit(&ds->ds_sendstream_lock);

        kmem_free(drr, sizeof (dmu_replay_record_t));
        kmem_free(dsp, sizeof (dmu_sendarg_t));

        return (err);
}

int
dmu_send_estimate(objset_t *tosnap, objset_t *fromsnap, boolean_t fromorigin,
    uint64_t *sizep)
{
        dsl_dataset_t *ds = tosnap->os_dsl_dataset;
        dsl_dataset_t *fromds = fromsnap ? fromsnap->os_dsl_dataset : NULL;
        dsl_pool_t *dp = ds->ds_dir->dd_pool;
        int err;
        uint64_t size;

        /* 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) {
                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;
                }
        }

        /* Get uncompressed size estimate of changed data. */
        if (fromds == NULL) {
                size = ds->ds_phys->ds_uncompressed_bytes;
        } else {
                uint64_t used, comp;
                err = dsl_dataset_space_written(fromds, ds,
                    &used, &comp, &size);
                if (fromorigin)
                        dsl_dataset_rele(fromds, FTAG);
                if (err)
                        return (err);
        }

        /*
         * Assume that space (both on-disk and in-stream) is dominated by
         * data.  We will adjust for indirect blocks and the copies property,
         * but ignore per-object space used (eg, dnodes and DRR_OBJECT records).
         */

        /*
         * Subtract out approximate space used by indirect blocks.
         * Assume most space is used by data blocks (non-indirect, non-dnode).
         * Assume all blocks are recordsize.  Assume ditto blocks and
         * internal fragmentation counter out compression.
         *
         * Therefore, space used by indirect blocks is sizeof(blkptr_t) per
         * block, which we observe in practice.
         */
        uint64_t recordsize;
        rw_enter(&dp->dp_config_rwlock, RW_READER);
        err = dsl_prop_get_ds(ds, "recordsize",
            sizeof (recordsize), 1, &recordsize, NULL);
        rw_exit(&dp->dp_config_rwlock);
        if (err)
                return (err);
        size -= size / recordsize * sizeof (blkptr_t);

        /* Add in the space for the record associated with each block. */
        size += size / recordsize * sizeof (dmu_replay_record_t);

        *sizep = size;

        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 */
        cred_t *cr;
};

/* ARGSUSED */
static int
recv_new_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 (!dsl_dataset_is_snapshot(rbsa->origin))
                        return (EINVAL);
                if (rbsa->origin->ds_phys->ds_guid != rbsa->fromguid)
                        return (ENODEV);
        }

        return (0);
}

static void
recv_new_sync(void *arg1, void *arg2, dmu_tx_t *tx)
{
        dsl_dir_t *dd = arg1;
        struct recvbeginsyncarg *rbsa = arg2;
        uint64_t flags = DS_FLAG_INCONSISTENT | rbsa->dsflags;
        uint64_t dsobj;

        /* Create and open new dataset. */
        dsobj = dsl_dataset_create_sync(dd, strrchr(rbsa->tofs, '/') + 1,
            rbsa->origin, flags, rbsa->cr, tx);
        VERIFY(0 == dsl_dataset_own_obj(dd->dd_pool, dsobj,
            B_TRUE, dmu_recv_tag, &rbsa->ds));

        if (rbsa->origin == NULL) {
                (void) dmu_objset_create_impl(dd->dd_pool->dp_spa,
                    rbsa->ds, &rbsa->ds->ds_phys->ds_bp, rbsa->type, tx);
        }

        spa_history_log_internal(LOG_DS_REPLAY_FULL_SYNC,
            dd->dd_pool->dp_spa, tx, "dataset = %lld", dsobj);
}

/* ARGSUSED */
static int
recv_existing_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);

        /* 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);

        if (rbsa->fromguid) {
                /* if incremental, most recent snapshot must match fromguid */
                if (ds->ds_prev == NULL)
                        return (ENODEV);

                /*
                 * most recent snapshot must match fromguid, or there are no
                 * changes since the fromguid one
                 */
                if (ds->ds_prev->ds_phys->ds_guid != rbsa->fromguid) {
                        uint64_t birth = ds->ds_prev->ds_phys->ds_bp.blk_birth;
                        uint64_t obj = ds->ds_prev->ds_phys->ds_prev_snap_obj;
                        while (obj != 0) {
                                dsl_dataset_t *snap;
                                err = dsl_dataset_hold_obj(ds->ds_dir->dd_pool,
                                    obj, FTAG, &snap);
                                if (err)
                                        return (ENODEV);
                                if (snap->ds_phys->ds_creation_txg < birth) {
                                        dsl_dataset_rele(snap, FTAG);
                                        return (ENODEV);
                                }
                                if (snap->ds_phys->ds_guid == rbsa->fromguid) {
                                        dsl_dataset_rele(snap, FTAG);
                                        break; /* it's ok */
                                }
                                obj = snap->ds_phys->ds_prev_snap_obj;
                                dsl_dataset_rele(snap, FTAG);
                        }
                        if (obj == 0)
                                return (ENODEV);
                }
        } else {
                /* if full, most recent snapshot must be $ORIGIN */
                if (ds->ds_phys->ds_prev_snap_txg >= TXG_INITIAL)
                        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);

        return (0);
}

/* ARGSUSED */
static void
recv_existing_sync(void *arg1, void *arg2, 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 *cds;
        uint64_t flags = DS_FLAG_INCONSISTENT | rbsa->dsflags;
        uint64_t dsobj;

        /* create and open the temporary clone */
        dsobj = dsl_dataset_create_sync(ohds->ds_dir, rbsa->clonelastname,
            ohds->ds_prev, flags, rbsa->cr, tx);
        VERIFY(0 == dsl_dataset_own_obj(dp, dsobj, B_TRUE, dmu_recv_tag, &cds));

        /*
         * If we actually created a non-clone, we need to create the
         * objset in our new dataset.
         */
        if (BP_IS_HOLE(dsl_dataset_get_blkptr(cds))) {
                (void) dmu_objset_create_impl(dp->dp_spa,
                    cds, dsl_dataset_get_blkptr(cds), rbsa->type, tx);
        }

        rbsa->ds = cds;

        spa_history_log_internal(LOG_DS_REPLAY_INC_SYNC,
            dp->dp_spa, tx, "dataset = %lld", dsobj);
}

static boolean_t
dmu_recv_verify_features(dsl_dataset_t *ds, struct drr_begin *drrb)
{
        int featureflags;

        featureflags = DMU_GET_FEATUREFLAGS(drrb->drr_versioninfo);

        /* Verify pool version supports SA if SA_SPILL feature set */
        return ((featureflags & DMU_BACKUP_FEATURE_SA_SPILL) &&
            (spa_version(dsl_dataset_get_spa(ds)) < SPA_VERSION_SA));
}

int
dmu_recv_begin(char *tofs, char *tosnap, char *top_ds, struct drr_begin *drrb,
    boolean_t force, objset_t *origin, dmu_recv_cookie_t *drc)
{
        int err = 0;
        boolean_t byteswap;
        struct recvbeginsyncarg rbsa = { 0 };
        uint64_t versioninfo;
        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_dsl_dataset : NULL;
        rbsa.fromguid = drrb->drr_fromguid;
        rbsa.type = drrb->drr_type;
        rbsa.tag = FTAG;
        rbsa.dsflags = 0;
        rbsa.cr = CRED();
        versioninfo = drrb->drr_versioninfo;
        flags = drrb->drr_flags;

        if (byteswap) {
                rbsa.type = BSWAP_32(rbsa.type);
                rbsa.fromguid = BSWAP_64(rbsa.fromguid);
                versioninfo = BSWAP_64(versioninfo);
                flags = BSWAP_32(flags);
        }

        if (DMU_GET_STREAM_HDRTYPE(versioninfo) == DMU_COMPOUNDSTREAM ||
            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_top_ds = top_ds;
        drc->drc_force = force;

        /*
         * Process the begin in syncing context.
         */

        /* open the dataset we are logically receiving into */
        err = dsl_dataset_hold(tofs, dmu_recv_tag, &ds);
        if (err == 0) {
                if (dmu_recv_verify_features(ds, drrb)) {
                        dsl_dataset_rele(ds, dmu_recv_tag);
                        return (ENOTSUP);
                }
                /* target fs already exists; recv into temp clone */

                /* Can't recv a clone into an existing fs */
                if (flags & DRR_FLAG_CLONE) {
                        dsl_dataset_rele(ds, dmu_recv_tag);
                        return (EINVAL);
                }

                /* must not have an incremental recv already in progress */
                if (!mutex_tryenter(&ds->ds_recvlock)) {
                        dsl_dataset_rele(ds, dmu_recv_tag);
                        return (EBUSY);
                }

                /* tmp clone name is: tofs/%tosnap" */
                (void) snprintf(rbsa.clonelastname, sizeof (rbsa.clonelastname),
                    "%%%s", tosnap);
                rbsa.force = force;
                err = dsl_sync_task_do(ds->ds_dir->dd_pool,
                    recv_existing_check, recv_existing_sync, ds, &rbsa, 5);
                if (err) {
                        mutex_exit(&ds->ds_recvlock);
                        dsl_dataset_rele(ds, dmu_recv_tag);
                        return (err);
                }
                drc->drc_logical_ds = ds;
                drc->drc_real_ds = rbsa.ds;
        } else if (err == ENOENT) {
                /* target fs does not exist; must be a full backup or clone */
                char *cp;

                /*
                 * If it's a non-clone incremental, we are missing the
                 * target fs, so fail the recv.
                 */
                if (rbsa.fromguid && !(flags & DRR_FLAG_CLONE))
                        return (ENOENT);

                /* Open the parent of tofs */
                cp = strrchr(tofs, '/');
                *cp = '\0';
                err = dsl_dataset_hold(tofs, FTAG, &ds);
                *cp = '/';
                if (err)
                        return (err);

                if (dmu_recv_verify_features(ds, drrb)) {
                        dsl_dataset_rele(ds, FTAG);
                        return (ENOTSUP);
                }

                err = dsl_sync_task_do(ds->ds_dir->dd_pool,
                    recv_new_check, recv_new_sync, ds->ds_dir, &rbsa, 5);
                dsl_dataset_rele(ds, FTAG);
                if (err)
                        return (err);
                drc->drc_logical_ds = drc->drc_real_ds = rbsa.ds;
                drc->drc_newfs = B_TRUE;
        }

        return (err);
}

struct restorearg {
        int err;
        int byteswap;
        kthread_t *td;
        struct file *fp;
        char *buf;
        uint64_t voff;
        int bufsize; /* amount of memory allocated for buf */
        zio_cksum_t cksum;
        avl_tree_t *guid_to_ds_map;
};

typedef struct guid_map_entry {
        uint64_t        guid;
        dsl_dataset_t   *gme_ds;
        avl_node_t      avlnode;
} guid_map_entry_t;

static int
guid_compare(const void *arg1, const void *arg2)
{
        const guid_map_entry_t *gmep1 = arg1;
        const guid_map_entry_t *gmep2 = arg2;

        if (gmep1->guid < gmep2->guid)
                return (-1);
        else if (gmep1->guid > gmep2->guid)
                return (1);
        return (0);
}

static void
free_guid_map_onexit(void *arg)
{
        avl_tree_t *ca = arg;
        void *cookie = NULL;
        guid_map_entry_t *gmep;

        while ((gmep = avl_destroy_nodes(ca, &cookie)) != NULL) {
                dsl_dataset_rele(gmep->gme_ds, ca);
                kmem_free(gmep, sizeof (guid_map_entry_t));
        }
        avl_destroy(ca);
        kmem_free(ca, sizeof (avl_tree_t));
}

static int
restore_bytes(struct restorearg *ra, void *buf, int len, off_t off, ssize_t *resid)
{
        struct uio auio;
        struct iovec aiov;
        int error;

        aiov.iov_base = buf;
        aiov.iov_len = len;
        auio.uio_iov = &aiov;
        auio.uio_iovcnt = 1;
        auio.uio_resid = len;
        auio.uio_segflg = UIO_SYSSPACE;
        auio.uio_rw = UIO_READ;
        auio.uio_offset = off;
        auio.uio_td = ra->td;
#ifdef _KERNEL
        error = fo_read(ra->fp, &auio, ra->td->td_ucred, FOF_OFFSET, ra->td);
#else
        fprintf(stderr, "%s: returning EOPNOTSUPP\n", __func__);
        error = EOPNOTSUPP;
#endif
        *resid = auio.uio_resid;
        return (error);
}

static void *
restore_read(struct restorearg *ra, int len)
{
        void *rv;
        int done = 0;

        /* some things will require 8-byte alignment, so everything must */
        ASSERT0(len % 8);

        while (done < len) {
                ssize_t resid;

                ra->err = restore_bytes(ra, (caddr_t)ra->buf + done,
                    len - done, ra->voff, &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_versioninfo);
                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);
                DO64(drr_object.drr_toguid);
                break;
        case DRR_FREEOBJECTS:
                DO64(drr_freeobjects.drr_firstobj);
                DO64(drr_freeobjects.drr_numobjs);
                DO64(drr_freeobjects.drr_toguid);
                break;
        case DRR_WRITE:
                DO64(drr_write.drr_object);
                DO32(drr_write.drr_type);
                DO64(drr_write.drr_offset);
                DO64(drr_write.drr_length);
                DO64(drr_write.drr_toguid);
                DO64(drr_write.drr_key.ddk_cksum.zc_word[0]);
                DO64(drr_write.drr_key.ddk_cksum.zc_word[1]);
                DO64(drr_write.drr_key.ddk_cksum.zc_word[2]);
                DO64(drr_write.drr_key.ddk_cksum.zc_word[3]);
                DO64(drr_write.drr_key.ddk_prop);
                break;
        case DRR_WRITE_BYREF:
                DO64(drr_write_byref.drr_object);
                DO64(drr_write_byref.drr_offset);
                DO64(drr_write_byref.drr_length);
                DO64(drr_write_byref.drr_toguid);
                DO64(drr_write_byref.drr_refguid);
                DO64(drr_write_byref.drr_refobject);
                DO64(drr_write_byref.drr_refoffset);
                DO64(drr_write_byref.drr_key.ddk_cksum.zc_word[0]);
                DO64(drr_write_byref.drr_key.ddk_cksum.zc_word[1]);
                DO64(drr_write_byref.drr_key.ddk_cksum.zc_word[2]);
                DO64(drr_write_byref.drr_key.ddk_cksum.zc_word[3]);
                DO64(drr_write_byref.drr_key.ddk_prop);
                break;
        case DRR_FREE:
                DO64(drr_free.drr_object);
                DO64(drr_free.drr_offset);
                DO64(drr_free.drr_length);
                DO64(drr_free.drr_toguid);
                break;
        case DRR_SPILL:
                DO64(drr_spill.drr_object);
                DO64(drr_spill.drr_length);
                DO64(drr_spill.drr_toguid);
                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]);
                DO64(drr_end.drr_toguid);
                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;

        if (drro->drr_type == DMU_OT_NONE ||
            !DMU_OT_IS_VALID(drro->drr_type) ||
            !DMU_OT_IS_VALID(drro->drr_bonustype) ||
            drro->drr_checksumtype >= 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);
        }

        err = dmu_object_info(os, drro->drr_object, NULL);

        if (err != 0 && err != ENOENT)
                return (EINVAL);

        if (drro->drr_bonuslen) {
                data = restore_read(ra, P2ROUNDUP(drro->drr_bonuslen, 8));
                if (ra->err)
                        return (ra->err);
        }

        if (err == ENOENT) {
                /* currently free, want to be allocated */
                tx = dmu_tx_create(os);
                dmu_tx_hold_bonus(tx, DMU_NEW_OBJECT);
                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);
                dmu_tx_commit(tx);
        } else {
                /* currently allocated, want to be allocated */
                err = dmu_object_reclaim(os, drro->drr_object,
                    drro->drr_type, drro->drr_blksz,
                    drro->drr_bonustype, drro->drr_bonuslen);
        }
        if (err) {
                return (EINVAL);
        }

        tx = dmu_tx_create(os);
        dmu_tx_hold_bonus(tx, drro->drr_object);
        err = dmu_tx_assign(tx, TXG_WAIT);
        if (err) {
                dmu_tx_abort(tx);
                return (err);
        }

        dmu_object_set_checksum(os, drro->drr_object, drro->drr_checksumtype,
            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_object_byteswap_t byteswap =
                            DMU_OT_BYTESWAP(drro->drr_bonustype);
                        dmu_ot_byteswap[byteswap].ob_func(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 ||
            !DMU_OT_IS_VALID(drrw->drr_type))
                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_object_byteswap_t byteswap =
                    DMU_OT_BYTESWAP(drrw->drr_type);
                dmu_ot_byteswap[byteswap].ob_func(data, drrw->drr_length);
        }
        dmu_write(os, drrw->drr_object,
            drrw->drr_offset, drrw->drr_length, data, tx);
        dmu_tx_commit(tx);
        return (0);
}

static int
restore_write_byref(struct restorearg *ra, objset_t *os,
    struct drr_write_byref *drrwbr)
{
        dmu_tx_t *tx;
        int err;
        guid_map_entry_t gmesrch;
        guid_map_entry_t *gmep;
        avl_index_t     where;
        objset_t *ref_os = NULL;
        dmu_buf_t *dbp;

        if (drrwbr->drr_offset + drrwbr->drr_length < drrwbr->drr_offset)
                return (EINVAL);

        /*
         * If the GUID of the referenced dataset is different from the
         * GUID of the target dataset, find the referenced dataset.
         */
        if (drrwbr->drr_toguid != drrwbr->drr_refguid) {
                gmesrch.guid = drrwbr->drr_refguid;
                if ((gmep = avl_find(ra->guid_to_ds_map, &gmesrch,
                    &where)) == NULL) {
                        return (EINVAL);
                }
                if (dmu_objset_from_ds(gmep->gme_ds, &ref_os))
                        return (EINVAL);
        } else {
                ref_os = os;
        }

        if (err = dmu_buf_hold(ref_os, drrwbr->drr_refobject,
            drrwbr->drr_refoffset, FTAG, &dbp, DMU_READ_PREFETCH))
                return (err);

        tx = dmu_tx_create(os);

        dmu_tx_hold_write(tx, drrwbr->drr_object,
            drrwbr->drr_offset, drrwbr->drr_length);
        err = dmu_tx_assign(tx, TXG_WAIT);
        if (err) {
                dmu_tx_abort(tx);
                return (err);
        }
        dmu_write(os, drrwbr->drr_object,
            drrwbr->drr_offset, drrwbr->drr_length, dbp->db_data, tx);
        dmu_buf_rele(dbp, FTAG);
        dmu_tx_commit(tx);
        return (0);
}

static int
restore_spill(struct restorearg *ra, objset_t *os, struct drr_spill *drrs)
{
        dmu_tx_t *tx;
        void *data;
        dmu_buf_t *db, *db_spill;
        int err;

        if (drrs->drr_length < SPA_MINBLOCKSIZE ||
            drrs->drr_length > SPA_MAXBLOCKSIZE)
                return (EINVAL);

        data = restore_read(ra, drrs->drr_length);
        if (data == NULL)
                return (ra->err);

        if (dmu_object_info(os, drrs->drr_object, NULL) != 0)
                return (EINVAL);

        VERIFY(0 == dmu_bonus_hold(os, drrs->drr_object, FTAG, &db));
        if ((err = dmu_spill_hold_by_bonus(db, FTAG, &db_spill)) != 0) {
                dmu_buf_rele(db, FTAG);
                return (err);
        }

        tx = dmu_tx_create(os);

        dmu_tx_hold_spill(tx, db->db_object);

        err = dmu_tx_assign(tx, TXG_WAIT);
        if (err) {
                dmu_buf_rele(db, FTAG);
                dmu_buf_rele(db_spill, FTAG);
                dmu_tx_abort(tx);
                return (err);
        }
        dmu_buf_will_dirty(db_spill, tx);

        if (db_spill->db_size < drrs->drr_length)
                VERIFY(0 == dbuf_spill_set_blksz(db_spill,
                    drrs->drr_length, tx));
        bcopy(data, db_spill->db_data, drrs->drr_length);

        dmu_buf_rele(db, FTAG);
        dmu_buf_rele(db_spill, FTAG);

        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);
}

int
dmu_recv_stream(dmu_recv_cookie_t *drc, struct file *fp, offset_t *voffp,
    int cleanup_fd, uint64_t *action_handlep)
{
        struct restorearg ra = { 0 };
        dmu_replay_record_t *drr;
        objset_t *os;
        zio_cksum_t pcksum;
        int featureflags;

        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_versioninfo = BSWAP_64(drrb->drr_versioninfo);
                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.td = curthread;
        ra.fp = fp;
        ra.voff = *voffp;
        ra.bufsize = 1<<20;
        ra.buf = kmem_alloc(ra.bufsize, KM_SLEEP);

        /* these were verified in dmu_recv_begin */
        ASSERT(DMU_GET_STREAM_HDRTYPE(drc->drc_drrb->drr_versioninfo) ==
            DMU_SUBSTREAM);
        ASSERT(drc->drc_drrb->drr_type < DMU_OST_NUMTYPES);

        /*
         * Open the objset we are modifying.
         */
        VERIFY(dmu_objset_from_ds(drc->drc_real_ds, &os) == 0);

        ASSERT(drc->drc_real_ds->ds_phys->ds_flags & DS_FLAG_INCONSISTENT);

        featureflags = DMU_GET_FEATUREFLAGS(drc->drc_drrb->drr_versioninfo);

        /* if this stream is dedup'ed, set up the avl tree for guid mapping */
        if (featureflags & DMU_BACKUP_FEATURE_DEDUP) {
                minor_t minor;

                if (cleanup_fd == -1) {
                        ra.err = EBADF;
                        goto out;
                }
                ra.err = zfs_onexit_fd_hold(cleanup_fd, &minor);
                if (ra.err) {
                        cleanup_fd = -1;
                        goto out;
                }

                if (*action_handlep == 0) {
                        ra.guid_to_ds_map =
                            kmem_alloc(sizeof (avl_tree_t), KM_SLEEP);
                        avl_create(ra.guid_to_ds_map, guid_compare,
                            sizeof (guid_map_entry_t),
                            offsetof(guid_map_entry_t, avlnode));
                        ra.err = zfs_onexit_add_cb(minor,
                            free_guid_map_onexit, ra.guid_to_ds_map,
                            action_handlep);
                        if (ra.err)
                                goto out;
                } else {
                        ra.err = zfs_onexit_cb_data(minor, *action_handlep,
                            (void **)&ra.guid_to_ds_map);
                        if (ra.err)
                                goto out;
                }

                drc->drc_guid_to_ds_map = ra.guid_to_ds_map;
        }

        /*
         * 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_WRITE_BYREF:
                {
                        struct drr_write_byref drrwbr =
                            drr->drr_u.drr_write_byref;
                        ra.err = restore_write_byref(&ra, os, &drrwbr);
                        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;
                }
                case DRR_SPILL:
                {
                        struct drr_spill drrs = drr->drr_u.drr_spill;
                        ra.err = restore_spill(&ra, os, &drrs);
                        break;
                }
                default:
                        ra.err = EINVAL;
                        goto out;
                }
                pcksum = ra.cksum;
        }
        ASSERT(ra.err != 0);

out:
        if ((featureflags & DMU_BACKUP_FEATURE_DEDUP) && (cleanup_fd != -1))
                zfs_onexit_fd_rele(cleanup_fd);

        if (ra.err != 0) {
                /*
                 * destroy what we created, so we don't leave it in the
                 * inconsistent restoring state.
                 */
                txg_wait_synced(drc->drc_real_ds->ds_dir->dd_pool, 0);

                (void) dsl_dataset_destroy(drc->drc_real_ds, dmu_recv_tag,
                    B_FALSE);
                if (drc->drc_real_ds != drc->drc_logical_ds) {
                        mutex_exit(&drc->drc_logical_ds->ds_recvlock);
                        dsl_dataset_rele(drc->drc_logical_ds, dmu_recv_tag);
                }
        }

        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, dmu_tx_t *tx)
{
        dsl_dataset_t *ds = arg1;
        struct recvendsyncarg *resa = arg2;

        dsl_dataset_snapshot_sync(ds, resa->tosnap, 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;
}

static int
add_ds_to_guidmap(avl_tree_t *guid_map, dsl_dataset_t *ds)
{
        dsl_pool_t *dp = ds->ds_dir->dd_pool;
        uint64_t snapobj = ds->ds_phys->ds_prev_snap_obj;
        dsl_dataset_t *snapds;
        guid_map_entry_t *gmep;
        int err;

        ASSERT(guid_map != NULL);

        rw_enter(&dp->dp_config_rwlock, RW_READER);
        err = dsl_dataset_hold_obj(dp, snapobj, guid_map, &snapds);
        if (err == 0) {
                gmep = kmem_alloc(sizeof (guid_map_entry_t), KM_SLEEP);
                gmep->guid = snapds->ds_phys->ds_guid;
                gmep->gme_ds = snapds;
                avl_add(guid_map, gmep);
        }

        rw_exit(&dp->dp_config_rwlock);
        return (err);
}

static int
dmu_recv_existing_end(dmu_recv_cookie_t *drc)
{
        struct recvendsyncarg resa;
        dsl_dataset_t *ds = drc->drc_logical_ds;
        int err, myerr;

        if (dsl_dataset_tryown(ds, FALSE, dmu_recv_tag)) {
                err = dsl_dataset_clone_swap(drc->drc_real_ds, ds,
                    drc->drc_force);
                if (err)
                        goto out;
        } else {
                mutex_exit(&ds->ds_recvlock);
                dsl_dataset_rele(ds, dmu_recv_tag);
                (void) dsl_dataset_destroy(drc->drc_real_ds, dmu_recv_tag,
                    B_FALSE);
                return (EBUSY);
        }

        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) {
                /* swap back */
                (void) dsl_dataset_clone_swap(drc->drc_real_ds, ds, B_TRUE);
        }

out:
        mutex_exit(&ds->ds_recvlock);
        if (err == 0 && drc->drc_guid_to_ds_map != NULL)
                (void) add_ds_to_guidmap(drc->drc_guid_to_ds_map, ds);
        dsl_dataset_disown(ds, dmu_recv_tag);
        myerr = dsl_dataset_destroy(drc->drc_real_ds, dmu_recv_tag, B_FALSE);
        ASSERT0(myerr);
        return (err);
}

static int
dmu_recv_new_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);

        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) {
                /* clean up the fs we just recv'd into */
                (void) dsl_dataset_destroy(ds, dmu_recv_tag, B_FALSE);
        } else {
                if (drc->drc_guid_to_ds_map != NULL)
                        (void) add_ds_to_guidmap(drc->drc_guid_to_ds_map, ds);
                /* release the hold from dmu_recv_begin */
                dsl_dataset_disown(ds, dmu_recv_tag);
        }
        return (err);
}

int
dmu_recv_end(dmu_recv_cookie_t *drc)
{
        if (drc->drc_logical_ds != drc->drc_real_ds)
                return (dmu_recv_existing_end(drc));
        else
                return (dmu_recv_new_end(drc));
}