4347 ZPL can use dmu_tx_assign(TXG_WAIT)
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Adam Leventhal <ahl@delphix.com>

*** 935,960 ****
          if (zfs_acl_ids_overquota(zfsvfs, &acl_ids)) {
                  zfs_acl_ids_free(&acl_ids);
                  return (SET_ERROR(EDQUOT));
          }
  
- top:
          tx = dmu_tx_create(zfsvfs->z_os);
          dmu_tx_hold_sa_create(tx, acl_ids.z_aclp->z_acl_bytes +
              ZFS_SA_BASE_ATTR_SIZE);
          dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_TRUE);
          dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, FALSE, NULL);
          fuid_dirtied = zfsvfs->z_fuid_dirty;
          if (fuid_dirtied)
                  zfs_fuid_txhold(zfsvfs, tx);
!         error = dmu_tx_assign(tx, TXG_NOWAIT);
          if (error) {
-                 if (error == ERESTART) {
-                         dmu_tx_wait(tx);
-                         dmu_tx_abort(tx);
-                         goto top;
-                 }
                  zfs_acl_ids_free(&acl_ids);
                  dmu_tx_abort(tx);
                  return (error);
          }
          zfs_mknode(zp, vap, tx, cr, IS_XATTR, &xzp, &acl_ids);
--- 935,954 ----
          if (zfs_acl_ids_overquota(zfsvfs, &acl_ids)) {
                  zfs_acl_ids_free(&acl_ids);
                  return (SET_ERROR(EDQUOT));
          }
  
          tx = dmu_tx_create(zfsvfs->z_os);
          dmu_tx_hold_sa_create(tx, acl_ids.z_aclp->z_acl_bytes +
              ZFS_SA_BASE_ATTR_SIZE);
          dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_TRUE);
          dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, FALSE, NULL);
          fuid_dirtied = zfsvfs->z_fuid_dirty;
          if (fuid_dirtied)
                  zfs_fuid_txhold(zfsvfs, tx);
!         error = dmu_tx_assign(tx, TXG_WAIT);
          if (error) {
                  zfs_acl_ids_free(&acl_ids);
                  dmu_tx_abort(tx);
                  return (error);
          }
          zfs_mknode(zp, vap, tx, cr, IS_XATTR, &xzp, &acl_ids);