Illumos #3498 panic in arc_read()
[zfs.git] / module / zfs / dmu_objset.c
index 690e6ec..ca75e52 100644 (file)
 #include <sys/zil.h>
 #include <sys/dmu_impl.h>
 #include <sys/zfs_ioctl.h>
-#include <sys/sunddi.h>
 #include <sys/sa.h>
+#include <sys/zfs_onexit.h>
+
+/*
+ * Needed to close a window in dnode_move() that allows the objset to be freed
+ * before it can be safely accessed.
+ */
+krwlock_t os_lock;
+
+void
+dmu_objset_init(void)
+{
+       rw_init(&os_lock, NULL, RW_DEFAULT, NULL);
+}
+
+void
+dmu_objset_fini(void)
+{
+       rw_destroy(&os_lock);
+}
 
 spa_t *
 dmu_objset_spa(objset_t *os)
@@ -244,7 +262,7 @@ dmu_objset_open_impl(spa_t *spa, dsl_dataset_t *ds, blkptr_t *bp,
 
        ASSERT(ds == NULL || MUTEX_HELD(&ds->ds_opening_lock));
 
-       os = kmem_zalloc(sizeof (objset_t), KM_SLEEP);
+       os = kmem_zalloc(sizeof (objset_t), KM_PUSHPAGE);
        os->os_dsl_dataset = ds;
        os->os_spa = spa;
        os->os_rootbp = bp;
@@ -258,12 +276,7 @@ dmu_objset_open_impl(spa_t *spa, dsl_dataset_t *ds, blkptr_t *bp,
                        aflags |= ARC_L2CACHE;
 
                dprintf_bp(os->os_rootbp, "reading %s", "");
-               /*
-                * XXX when bprewrite scrub can change the bp,
-                * and this is called from dmu_objset_open_ds_os, the bp
-                * could change, and we'll need a lock.
-                */
-               err = dsl_read_nolock(NULL, spa, os->os_rootbp,
+               err = arc_read(NULL, spa, os->os_rootbp,
                    arc_getbuf_func, &os->os_phys_buf,
                    ZIO_PRIORITY_SYNC_READ, ZIO_FLAG_CANFAIL, &aflags, &zb);
                if (err) {
@@ -350,7 +363,8 @@ dmu_objset_open_impl(spa_t *spa, dsl_dataset_t *ds, blkptr_t *bp,
                os->os_secondary_cache = ZFS_CACHE_ALL;
        }
 
-       os->os_zil_header = os->os_phys->os_zil_header;
+       if (ds == NULL || !dsl_dataset_is_snapshot(ds))
+               os->os_zil_header = os->os_phys->os_zil_header;
        os->os_zil = zil_alloc(os, &os->os_zil_header);
 
        for (i = 0; i < TXG_SIZE; i++) {
@@ -368,13 +382,16 @@ dmu_objset_open_impl(spa_t *spa, dsl_dataset_t *ds, blkptr_t *bp,
        mutex_init(&os->os_obj_lock, NULL, MUTEX_DEFAULT, NULL);
        mutex_init(&os->os_user_ptr_lock, NULL, MUTEX_DEFAULT, NULL);
 
-       os->os_meta_dnode = dnode_special_open(os,
-           &os->os_phys->os_meta_dnode, DMU_META_DNODE_OBJECT);
+       DMU_META_DNODE(os) = dnode_special_open(os,
+           &os->os_phys->os_meta_dnode, DMU_META_DNODE_OBJECT,
+           &os->os_meta_dnode);
        if (arc_buf_size(os->os_phys_buf) >= sizeof (objset_phys_t)) {
-               os->os_userused_dnode = dnode_special_open(os,
-                   &os->os_phys->os_userused_dnode, DMU_USERUSED_OBJECT);
-               os->os_groupused_dnode = dnode_special_open(os,
-                   &os->os_phys->os_groupused_dnode, DMU_GROUPUSED_OBJECT);
+               DMU_USERUSED_DNODE(os) = dnode_special_open(os,
+                   &os->os_phys->os_userused_dnode, DMU_USERUSED_OBJECT,
+                   &os->os_userused_dnode);
+               DMU_GROUPUSED_DNODE(os) = dnode_special_open(os,
+                   &os->os_phys->os_groupused_dnode, DMU_GROUPUSED_OBJECT,
+                   &os->os_groupused_dnode);
        }
 
        /*
@@ -401,7 +418,7 @@ dmu_objset_from_ds(dsl_dataset_t *ds, objset_t **osp)
        *osp = ds->ds_objset;
        if (*osp == NULL) {
                err = dmu_objset_open_impl(dsl_dataset_get_spa(ds),
-                   ds, &ds->ds_phys->ds_bp, osp);
+                   ds, dsl_dataset_get_blkptr(ds), osp);
        }
        mutex_exit(&ds->ds_opening_lock);
        return (err);
@@ -470,8 +487,8 @@ dmu_objset_evict_dbufs(objset_t *os)
        mutex_enter(&os->os_lock);
 
        /* process the mdn last, since the other dnodes have holds on it */
-       list_remove(&os->os_dnodes, os->os_meta_dnode);
-       list_insert_tail(&os->os_dnodes, os->os_meta_dnode);
+       list_remove(&os->os_dnodes, DMU_META_DNODE(os));
+       list_insert_tail(&os->os_dnodes, DMU_META_DNODE(os));
 
        /*
         * Find the first dnode with holds.  We have to do this dance
@@ -497,16 +514,18 @@ dmu_objset_evict_dbufs(objset_t *os)
                mutex_enter(&os->os_lock);
                dn = next_dn;
        }
+       dn = list_head(&os->os_dnodes);
        mutex_exit(&os->os_lock);
-       return (list_head(&os->os_dnodes) != os->os_meta_dnode);
+       return (dn != DMU_META_DNODE(os));
 }
 
 void
 dmu_objset_evict(objset_t *os)
 {
        dsl_dataset_t *ds = os->os_dsl_dataset;
+       int t;
 
-       for (int t = 0; t < TXG_SIZE; t++)
+       for (t = 0; t < TXG_SIZE; t++)
                ASSERT(!dmu_objset_is_dirty(os, t));
 
        if (ds) {
@@ -539,16 +558,26 @@ dmu_objset_evict(objset_t *os)
         */
        (void) dmu_objset_evict_dbufs(os);
 
-       dnode_special_close(os->os_meta_dnode);
-       if (os->os_userused_dnode) {
-               dnode_special_close(os->os_userused_dnode);
-               dnode_special_close(os->os_groupused_dnode);
+       dnode_special_close(&os->os_meta_dnode);
+       if (DMU_USERUSED_DNODE(os)) {
+               dnode_special_close(&os->os_userused_dnode);
+               dnode_special_close(&os->os_groupused_dnode);
        }
        zil_free(os->os_zil);
 
        ASSERT3P(list_head(&os->os_dnodes), ==, NULL);
 
        VERIFY(arc_buf_remove_ref(os->os_phys_buf, &os->os_phys_buf) == 1);
+
+       /*
+        * This is a barrier to prevent the objset from going away in
+        * dnode_move() until we can safely ensure that the objset is still in
+        * use. We consider the objset valid before the barrier and invalid
+        * after the barrier.
+        */
+       rw_enter(&os_lock, RW_READER);
+       rw_exit(&os_lock);
+
        mutex_destroy(&os->os_lock);
        mutex_destroy(&os->os_obj_lock);
        mutex_destroy(&os->os_user_ptr_lock);
@@ -570,12 +599,12 @@ dmu_objset_create_impl(spa_t *spa, dsl_dataset_t *ds, blkptr_t *bp,
        dnode_t *mdn;
 
        ASSERT(dmu_tx_is_syncing(tx));
-       if (ds)
-               mutex_enter(&ds->ds_opening_lock);
-       VERIFY(0 == dmu_objset_open_impl(spa, ds, bp, &os));
-       if (ds)
-               mutex_exit(&ds->ds_opening_lock);
-       mdn = os->os_meta_dnode;
+       if (ds != NULL)
+               VERIFY(0 == dmu_objset_from_ds(ds, &os));
+       else
+               VERIFY(0 == dmu_objset_open_impl(spa, NULL, bp, &os));
+
+       mdn = DMU_META_DNODE(os);
 
        dnode_allocate(mdn, DMU_OT_DNODE, 1 << DNODE_BLOCK_SHIFT,
            DN_MAX_INDBLKSHIFT, DMU_OT_NONE, 0, tx);
@@ -663,34 +692,33 @@ static void
 dmu_objset_create_sync(void *arg1, void *arg2, dmu_tx_t *tx)
 {
        dsl_dir_t *dd = arg1;
+       spa_t *spa = dd->dd_pool->dp_spa;
        struct oscarg *oa = arg2;
-       uint64_t dsobj;
+       uint64_t obj;
 
        ASSERT(dmu_tx_is_syncing(tx));
 
-       dsobj = dsl_dataset_create_sync(dd, oa->lastname,
+       obj = dsl_dataset_create_sync(dd, oa->lastname,
            oa->clone_origin, oa->flags, oa->cr, tx);
 
        if (oa->clone_origin == NULL) {
+               dsl_pool_t *dp = dd->dd_pool;
                dsl_dataset_t *ds;
                blkptr_t *bp;
                objset_t *os;
 
-               VERIFY(0 == dsl_dataset_hold_obj(dd->dd_pool, dsobj,
-                   FTAG, &ds));
+               VERIFY3U(0, ==, dsl_dataset_hold_obj(dp, obj, FTAG, &ds));
                bp = dsl_dataset_get_blkptr(ds);
                ASSERT(BP_IS_HOLE(bp));
 
-               os = dmu_objset_create_impl(dsl_dataset_get_spa(ds),
-                   ds, bp, oa->type, tx);
+               os = dmu_objset_create_impl(spa, ds, bp, oa->type, tx);
 
                if (oa->userfunc)
                        oa->userfunc(os, oa->userarg, oa->cr, tx);
                dsl_dataset_rele(ds, FTAG);
        }
 
-       spa_history_log_internal(LOG_DS_CREATE, dd->dd_pool->dp_spa,
-           tx, "dataset = %llu", dsobj);
+       spa_history_log_internal(LOG_DS_CREATE, spa, tx, "dataset = %llu", obj);
 }
 
 int
@@ -758,18 +786,8 @@ dmu_objset_destroy(const char *name, boolean_t defer)
        dsl_dataset_t *ds;
        int error;
 
-       /*
-        * dsl_dataset_destroy() can free any claimed-but-unplayed
-        * intent log, but if there is an active log, it has blocks that
-        * are allocated, but may not yet be reflected in the on-disk
-        * structure.  Only the ZIL knows how to free them, so we have
-        * to call into it here.
-        */
        error = dsl_dataset_own(name, B_TRUE, FTAG, &ds);
        if (error == 0) {
-               objset_t *os;
-               if (dmu_objset_from_ds(ds, &os) == 0)
-                       zil_destroy(dmu_objset_zil(os), B_FALSE);
                error = dsl_dataset_destroy(ds, FTAG, defer);
                /* dsl_dataset_destroy() closes the ds. */
        }
@@ -780,9 +798,14 @@ dmu_objset_destroy(const char *name, boolean_t defer)
 struct snaparg {
        dsl_sync_task_group_t *dstg;
        char *snapname;
+       char *htag;
        char failed[MAXPATHLEN];
        boolean_t recursive;
+       boolean_t needsuspend;
+       boolean_t temporary;
        nvlist_t *props;
+       struct dsl_ds_holdarg *ha;      /* only needed in the temporary case */
+       dsl_dataset_t *newds;
 };
 
 static int
@@ -790,11 +813,41 @@ snapshot_check(void *arg1, void *arg2, dmu_tx_t *tx)
 {
        objset_t *os = arg1;
        struct snaparg *sn = arg2;
+       int error;
 
        /* The props have already been checked by zfs_check_userprops(). */
 
-       return (dsl_dataset_snapshot_check(os->os_dsl_dataset,
-           sn->snapname, tx));
+       error = dsl_dataset_snapshot_check(os->os_dsl_dataset,
+           sn->snapname, tx);
+       if (error)
+               return (error);
+
+       if (sn->temporary) {
+               /*
+                * Ideally we would just call
+                * dsl_dataset_user_hold_check() and
+                * dsl_dataset_destroy_check() here.  However the
+                * dataset we want to hold and destroy is the snapshot
+                * that we just confirmed we can create, but it won't
+                * exist until after these checks are run.  Do any
+                * checks we can here and if more checks are added to
+                * those routines in the future, similar checks may be
+                * necessary here.
+                */
+               if (spa_version(os->os_spa) < SPA_VERSION_USERREFS)
+                       return (ENOTSUP);
+               /*
+                * Not checking number of tags because the tag will be
+                * unique, as it will be the only tag.
+                */
+               if (strlen(sn->htag) + MAX_TAG_PREFIX_LEN >= MAXNAMELEN)
+                       return (E2BIG);
+
+               sn->ha = kmem_alloc(sizeof(struct dsl_ds_holdarg), KM_PUSHPAGE);
+               sn->ha->temphold = B_TRUE;
+               sn->ha->htag = sn->htag;
+       }
+       return (error);
 }
 
 static void
@@ -812,6 +865,19 @@ snapshot_sync(void *arg1, void *arg2, dmu_tx_t *tx)
                pa.pa_source = ZPROP_SRC_LOCAL;
                dsl_props_set_sync(ds->ds_prev, &pa, tx);
        }
+
+       if (sn->temporary) {
+               struct dsl_ds_destroyarg da;
+
+               dsl_dataset_user_hold_sync(ds->ds_prev, sn->ha, tx);
+               kmem_free(sn->ha, sizeof (struct dsl_ds_holdarg));
+               sn->ha = NULL;
+               sn->newds = ds->ds_prev;
+
+               da.ds = ds->ds_prev;
+               da.defer = B_TRUE;
+               dsl_dataset_destroy_sync(&da, FTAG, tx);
+       }
 }
 
 static int
@@ -857,66 +923,90 @@ dmu_objset_snapshot_one(const char *name, void *arg)
                return (sn->recursive ? 0 : EBUSY);
        }
 
-       /*
-        * NB: we need to wait for all in-flight changes to get to disk,
-        * so that we snapshot those changes.  zil_suspend does this as
-        * a side effect.
-        */
-       err = zil_suspend(dmu_objset_zil(os));
-       if (err == 0) {
-               dsl_sync_task_create(sn->dstg, snapshot_check,
-                   snapshot_sync, os, sn, 3);
-       } else {
-               dmu_objset_rele(os, sn);
+       if (sn->needsuspend) {
+               err = zil_suspend(dmu_objset_zil(os));
+               if (err) {
+                       dmu_objset_rele(os, sn);
+                       return (err);
+               }
        }
+       dsl_sync_task_create(sn->dstg, snapshot_check, snapshot_sync,
+           os, sn, 3);
 
-       return (err);
+       return (0);
 }
 
 int
-dmu_objset_snapshot(char *fsname, char *snapname,
-    nvlist_t *props, boolean_t recursive)
+dmu_objset_snapshot(char *fsname, char *snapname, char *tag,
+    nvlist_t *props, boolean_t recursive, boolean_t temporary, int cleanup_fd)
 {
        dsl_sync_task_t *dst;
-       struct snaparg sn;
+       struct snaparg *sn;
        spa_t *spa;
+       minor_t minor;
        int err;
 
-       (void) strcpy(sn.failed, fsname);
+       sn = kmem_alloc(sizeof (struct snaparg), KM_SLEEP);
+       (void) strcpy(sn->failed, fsname);
 
        err = spa_open(fsname, &spa, FTAG);
-       if (err)
+       if (err) {
+               kmem_free(sn, sizeof (struct snaparg));
                return (err);
+       }
+
+       if (temporary) {
+               if (cleanup_fd < 0) {
+                       spa_close(spa, FTAG);
+                       return (EINVAL);
+               }
+               if ((err = zfs_onexit_fd_hold(cleanup_fd, &minor)) != 0) {
+                       spa_close(spa, FTAG);
+                       return (err);
+               }
+       }
 
-       sn.dstg = dsl_sync_task_group_create(spa_get_dsl(spa));
-       sn.snapname = snapname;
-       sn.props = props;
-       sn.recursive = recursive;
+       sn->dstg = dsl_sync_task_group_create(spa_get_dsl(spa));
+       sn->snapname = snapname;
+       sn->htag = tag;
+       sn->props = props;
+       sn->recursive = recursive;
+       sn->needsuspend = (spa_version(spa) < SPA_VERSION_FAST_SNAP);
+       sn->temporary = temporary;
+       sn->ha = NULL;
+       sn->newds = NULL;
 
        if (recursive) {
                err = dmu_objset_find(fsname,
-                   dmu_objset_snapshot_one, &sn, DS_FIND_CHILDREN);
+                   dmu_objset_snapshot_one, sn, DS_FIND_CHILDREN);
        } else {
-               err = dmu_objset_snapshot_one(fsname, &sn);
+               err = dmu_objset_snapshot_one(fsname, sn);
        }
 
        if (err == 0)
-               err = dsl_sync_task_group_wait(sn.dstg);
+               err = dsl_sync_task_group_wait(sn->dstg);
 
-       for (dst = list_head(&sn.dstg->dstg_tasks); dst;
-           dst = list_next(&sn.dstg->dstg_tasks, dst)) {
+       for (dst = list_head(&sn->dstg->dstg_tasks); dst;
+           dst = list_next(&sn->dstg->dstg_tasks, dst)) {
                objset_t *os = dst->dst_arg1;
                dsl_dataset_t *ds = os->os_dsl_dataset;
-               if (dst->dst_err)
-                       dsl_dataset_name(ds, sn.failed);
-               zil_resume(dmu_objset_zil(os));
-               dmu_objset_rele(os, &sn);
+               if (dst->dst_err) {
+                       dsl_dataset_name(ds, sn->failed);
+               } else if (temporary) {
+                       dsl_register_onexit_hold_cleanup(sn->newds, tag, minor);
+               }
+               if (sn->needsuspend)
+                       zil_resume(dmu_objset_zil(os));
+               dmu_objset_rele(os, sn);
        }
 
        if (err)
-               (void) strcpy(fsname, sn.failed);
-       dsl_sync_task_group_destroy(sn.dstg);
+               (void) strcpy(fsname, sn->failed);
+       if (temporary)
+               zfs_onexit_fd_rele(cleanup_fd);
+       dsl_sync_task_group_destroy(sn->dstg);
        spa_close(spa, FTAG);
+       kmem_free(sn, sizeof (struct snaparg));
        return (err);
 }
 
@@ -925,7 +1015,7 @@ dmu_objset_sync_dnodes(list_t *list, list_t *newlist, dmu_tx_t *tx)
 {
        dnode_t *dn;
 
-       while (dn = list_head(list)) {
+       while ((dn = list_head(list))) {
                ASSERT(dn->dn_object != DMU_META_DNODE_OBJECT);
                ASSERT(dn->dn_dbuf->db_data_pending);
                /*
@@ -951,6 +1041,8 @@ dmu_objset_sync_dnodes(list_t *list, list_t *newlist, dmu_tx_t *tx)
 static void
 dmu_objset_write_ready(zio_t *zio, arc_buf_t *abuf, void *arg)
 {
+       int i;
+
        blkptr_t *bp = zio->io_bp;
        objset_t *os = arg;
        dnode_phys_t *dnp = &os->os_phys->os_meta_dnode;
@@ -966,7 +1058,7 @@ dmu_objset_write_ready(zio_t *zio, arc_buf_t *abuf, void *arg)
         * dnode and user/group accounting objects).
         */
        bp->blk_fill = 0;
-       for (int i = 0; i < dnp->dn_nblkptr; i++)
+       for (i = 0; i < dnp->dn_nblkptr; i++)
                bp->blk_fill += dnp->dn_blkptr[i].blk_fill;
 }
 
@@ -1022,8 +1114,7 @@ dmu_objset_sync(objset_t *os, zio_t *pio, dmu_tx_t *tx)
        SET_BOOKMARK(&zb, os->os_dsl_dataset ?
            os->os_dsl_dataset->ds_object : DMU_META_OBJSET,
            ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
-       VERIFY3U(0, ==, arc_release_bp(os->os_phys_buf, &os->os_phys_buf,
-           os->os_rootbp, os->os_spa, &zb));
+       arc_release(os->os_phys_buf, &os->os_phys_buf);
 
        dmu_write_policy(os, NULL, 0, 0, &zp);
 
@@ -1035,17 +1126,17 @@ dmu_objset_sync(objset_t *os, zio_t *pio, dmu_tx_t *tx)
        /*
         * Sync special dnodes - the parent IO for the sync is the root block
         */
-       os->os_meta_dnode->dn_zio = zio;
-       dnode_sync(os->os_meta_dnode, tx);
+       DMU_META_DNODE(os)->dn_zio = zio;
+       dnode_sync(DMU_META_DNODE(os), tx);
 
        os->os_phys->os_flags = os->os_flags;
 
-       if (os->os_userused_dnode &&
-           os->os_userused_dnode->dn_type != DMU_OT_NONE) {
-               os->os_userused_dnode->dn_zio = zio;
-               dnode_sync(os->os_userused_dnode, tx);
-               os->os_groupused_dnode->dn_zio = zio;
-               dnode_sync(os->os_groupused_dnode, tx);
+       if (DMU_USERUSED_DNODE(os) &&
+           DMU_USERUSED_DNODE(os)->dn_type != DMU_OT_NONE) {
+               DMU_USERUSED_DNODE(os)->dn_zio = zio;
+               dnode_sync(DMU_USERUSED_DNODE(os), tx);
+               DMU_GROUPUSED_DNODE(os)->dn_zio = zio;
+               dnode_sync(DMU_GROUPUSED_DNODE(os), tx);
        }
 
        txgoff = tx->tx_txg & TXG_MASK;
@@ -1063,8 +1154,8 @@ dmu_objset_sync(objset_t *os, zio_t *pio, dmu_tx_t *tx)
        dmu_objset_sync_dnodes(&os->os_free_dnodes[txgoff], newlist, tx);
        dmu_objset_sync_dnodes(&os->os_dirty_dnodes[txgoff], newlist, tx);
 
-       list = &os->os_meta_dnode->dn_dirty_records[txgoff];
-       while (dr = list_head(list)) {
+       list = &DMU_META_DNODE(os)->dn_dirty_records[txgoff];
+       while ((dr = list_head(list)) != NULL) {
                ASSERT(dr->dr_dbuf->db_level == 0);
                list_remove(list, dr);
                if (dr->dr_zio)
@@ -1085,7 +1176,7 @@ dmu_objset_is_dirty(objset_t *os, uint64_t txg)
            !list_is_empty(&os->os_free_dnodes[txg & TXG_MASK]));
 }
 
-objset_used_cb_t *used_cbs[DMU_OST_NUMTYPES];
+static objset_used_cb_t *used_cbs[DMU_OST_NUMTYPES];
 
 void
 dmu_objset_register_type(dmu_objset_type_t ost, objset_used_cb_t *cb)
@@ -1097,8 +1188,8 @@ boolean_t
 dmu_objset_userused_enabled(objset_t *os)
 {
        return (spa_version(os->os_spa) >= SPA_VERSION_USERSPACE &&
-           used_cbs[os->os_phys->os_type] &&
-           os->os_userused_dnode);
+           used_cbs[os->os_phys->os_type] != NULL &&
+           DMU_USERUSED_DNODE(os) != NULL);
 }
 
 static void
@@ -1124,14 +1215,15 @@ dmu_objset_do_userquota_updates(objset_t *os, dmu_tx_t *tx)
 
        ASSERT(list_head(list) == NULL || dmu_objset_userused_enabled(os));
 
-       while (dn = list_head(list)) {
+       while ((dn = list_head(list)) != NULL) {
+               int flags;
                ASSERT(!DMU_OBJECT_IS_SPECIAL(dn->dn_object));
                ASSERT(dn->dn_phys->dn_type == DMU_OT_NONE ||
                    dn->dn_phys->dn_flags &
                    DNODE_FLAG_USERUSED_ACCOUNTED);
 
                /* Allocate the user/groupused objects if necessary. */
-               if (os->os_userused_dnode->dn_type == DMU_OT_NONE) {
+               if (DMU_USERUSED_DNODE(os)->dn_type == DMU_OT_NONE) {
                        VERIFY(0 == zap_create_claim(os,
                            DMU_USERUSED_OBJECT,
                            DMU_OT_USERGROUP_USED, DMU_OT_NONE, 0, tx));
@@ -1148,18 +1240,19 @@ dmu_objset_do_userquota_updates(objset_t *os, dmu_tx_t *tx)
                 * a bprewrite.
                 */
 
-               mutex_enter(&dn->dn_mtx);
-               ASSERT(dn->dn_id_flags);
-               if (dn->dn_id_flags & DN_ID_OLD_EXIST)  {
+               flags = dn->dn_id_flags;
+               ASSERT(flags);
+               if (flags & DN_ID_OLD_EXIST)  {
                        do_userquota_update(os, dn->dn_oldused, dn->dn_oldflags,
                            dn->dn_olduid, dn->dn_oldgid, B_TRUE, tx);
                }
-               if (dn->dn_id_flags & DN_ID_NEW_EXIST) {
+               if (flags & DN_ID_NEW_EXIST) {
                        do_userquota_update(os, DN_USED_BYTES(dn->dn_phys),
                            dn->dn_phys->dn_flags,  dn->dn_newuid,
                            dn->dn_newgid, B_FALSE, tx);
                }
 
+               mutex_enter(&dn->dn_mtx);
                dn->dn_oldused = 0;
                dn->dn_oldflags = 0;
                if (dn->dn_id_flags & DN_ID_NEW_EXIST) {
@@ -1199,13 +1292,23 @@ dmu_objset_userquota_find_data(dmu_buf_impl_t *db, dmu_tx_t *tx)
                if (dr->dr_txg == tx->tx_txg)
                        break;
 
-       if (dr == NULL)
+       if (dr == NULL) {
                data = NULL;
-       else if (dr->dr_dbuf->db_dnode->dn_bonuslen == 0 &&
-           dr->dr_dbuf->db_blkid == DMU_SPILL_BLKID)
-               data = dr->dt.dl.dr_data->b_data;
-       else
-               data = dr->dt.dl.dr_data;
+       } else {
+               dnode_t *dn;
+
+               DB_DNODE_ENTER(dr->dr_dbuf);
+               dn = DB_DNODE(dr->dr_dbuf);
+
+               if (dn->dn_bonuslen == 0 &&
+                   dr->dr_dbuf->db_blkid == DMU_SPILL_BLKID)
+                       data = dr->dt.dl.dr_data->b_data;
+               else
+                       data = dr->dt.dl.dr_data;
+
+               DB_DNODE_EXIT(dr->dr_dbuf);
+       }
+
        return (data);
 }
 
@@ -1215,7 +1318,7 @@ dmu_objset_userquota_get_ids(dnode_t *dn, boolean_t before, dmu_tx_t *tx)
        objset_t *os = dn->dn_objset;
        void *data = NULL;
        dmu_buf_impl_t *db = NULL;
-       uint64_t *user, *group;
+       uint64_t *user = NULL, *group = NULL;
        int flags = dn->dn_id_flags;
        int error;
        boolean_t have_spill = B_FALSE;
@@ -1242,7 +1345,8 @@ dmu_objset_userquota_get_ids(dnode_t *dn, boolean_t before, dmu_tx_t *tx)
 
                        if (RW_WRITE_HELD(&dn->dn_struct_rwlock))
                                rf |= DB_RF_HAVESTRUCT;
-                       error = dmu_spill_hold_by_dnode(dn, rf,
+                       error = dmu_spill_hold_by_dnode(dn,
+                           rf | DB_RF_MUST_SUCCEED,
                            FTAG, (dmu_buf_t **)&db);
                        ASSERT(error == 0);
                        mutex_enter(&db->db_mtx);
@@ -1464,6 +1568,12 @@ dmu_snapshot_list_next(objset_t *os, int namelen, char *name,
 }
 
 int
+dmu_snapshot_lookup(objset_t *os, const char *name, uint64_t *value)
+{
+       return dsl_dataset_snap_lookup(os->os_dsl_dataset, name, value);
+}
+
+int
 dmu_dir_list_next(objset_t *os, int namelen, char *name,
     uint64_t *idp, uint64_t *offp)
 {
@@ -1556,7 +1666,7 @@ dmu_objset_find_spa(spa_t *spa, const char *name,
        }
 
        thisobj = dd->dd_phys->dd_head_dataset_obj;
-       attr = kmem_alloc(sizeof (zap_attribute_t), KM_SLEEP);
+       attr = kmem_alloc(sizeof (zap_attribute_t), KM_PUSHPAGE);
        dp = dd->dd_pool;
 
        /*
@@ -1649,7 +1759,7 @@ dmu_objset_prefetch(const char *name, void *arg)
                        SET_BOOKMARK(&zb, ds->ds_object, ZB_ROOT_OBJECT,
                            ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
 
-                       (void) dsl_read_nolock(NULL, dsl_dataset_get_spa(ds),
+                       (void) arc_read(NULL, dsl_dataset_get_spa(ds),
                            &ds->ds_phys->ds_bp, NULL, NULL,
                            ZIO_PRIORITY_ASYNC_READ,
                            ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
@@ -1675,3 +1785,43 @@ dmu_objset_get_user(objset_t *os)
        ASSERT(MUTEX_HELD(&os->os_user_ptr_lock));
        return (os->os_user_ptr);
 }
+
+#if defined(_KERNEL) && defined(HAVE_SPL)
+EXPORT_SYMBOL(dmu_objset_zil);
+EXPORT_SYMBOL(dmu_objset_pool);
+EXPORT_SYMBOL(dmu_objset_ds);
+EXPORT_SYMBOL(dmu_objset_type);
+EXPORT_SYMBOL(dmu_objset_name);
+EXPORT_SYMBOL(dmu_objset_hold);
+EXPORT_SYMBOL(dmu_objset_own);
+EXPORT_SYMBOL(dmu_objset_rele);
+EXPORT_SYMBOL(dmu_objset_disown);
+EXPORT_SYMBOL(dmu_objset_from_ds);
+EXPORT_SYMBOL(dmu_objset_create);
+EXPORT_SYMBOL(dmu_objset_clone);
+EXPORT_SYMBOL(dmu_objset_destroy);
+EXPORT_SYMBOL(dmu_objset_snapshot);
+EXPORT_SYMBOL(dmu_objset_stats);
+EXPORT_SYMBOL(dmu_objset_fast_stat);
+EXPORT_SYMBOL(dmu_objset_spa);
+EXPORT_SYMBOL(dmu_objset_space);
+EXPORT_SYMBOL(dmu_objset_fsid_guid);
+EXPORT_SYMBOL(dmu_objset_find);
+EXPORT_SYMBOL(dmu_objset_find_spa);
+EXPORT_SYMBOL(dmu_objset_prefetch);
+EXPORT_SYMBOL(dmu_objset_byteswap);
+EXPORT_SYMBOL(dmu_objset_evict_dbufs);
+EXPORT_SYMBOL(dmu_objset_snap_cmtime);
+
+EXPORT_SYMBOL(dmu_objset_sync);
+EXPORT_SYMBOL(dmu_objset_is_dirty);
+EXPORT_SYMBOL(dmu_objset_create_impl);
+EXPORT_SYMBOL(dmu_objset_open_impl);
+EXPORT_SYMBOL(dmu_objset_evict);
+EXPORT_SYMBOL(dmu_objset_register_type);
+EXPORT_SYMBOL(dmu_objset_do_userquota_updates);
+EXPORT_SYMBOL(dmu_objset_userquota_get_ids);
+EXPORT_SYMBOL(dmu_objset_userused_enabled);
+EXPORT_SYMBOL(dmu_objset_userspace_upgrade);
+EXPORT_SYMBOL(dmu_objset_userspace_present);
+#endif