2619 asynchronous destruction of ZFS file systems
2747 SPA versioning with zfs feature flags
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <gwilson@delphix.com>
Reviewed by: Richard Lowe <richlowe@richlowe.net>
Reviewed by: Dan Kruchinin <dan.kruchinin@gmail.com>
Approved by: Dan McDonald <danmcd@nexenta.com>

*** 424,434 ****
          } else {
                  /*
                   * To simulate partial disk writes, we split writes into two
                   * system calls so that the process can be killed in between.
                   */
!                 split = (len > 0 ? rand() % len : 0);
                  iolen = pwrite64(vp->v_fd, addr, split, offset);
                  iolen += pwrite64(vp->v_fd, (char *)addr + split,
                      len - split, offset + split);
          }
  
--- 424,436 ----
          } else {
                  /*
                   * To simulate partial disk writes, we split writes into two
                   * system calls so that the process can be killed in between.
                   */
!                 int sectors = len >> SPA_MINBLOCKSHIFT;
!                 split = (sectors > 0 ? rand() % sectors : 0) <<
!                     SPA_MINBLOCKSHIFT;
                  iolen = pwrite64(vp->v_fd, addr, split, offset);
                  iolen += pwrite64(vp->v_fd, (char *)addr + split,
                      len - split, offset + split);
          }