Method _sync_write

src/blk/kernel/KernelDevice.cc:1052–1113

}

int KernelDevice::_sync_write(uint64_t off, bufferlist &bl, bool buffered, int write_hint)
{
  uint64_t len = bl.length();
  dout(5) << __func__ << " 0x" << std::hex << off << "~" << len
	  << std::dec << " " << buffermode(buffered) << dendl;
  if (cct->_conf->bdev_inject_crash &&
      rand() % cct->_conf->bdev_inject_crash == 0) {
    derr << __func__ << " bdev_inject_crash: dropping io 0x" << std::hex
	 << off << "~" << len << std::dec << dendl;
    ++injecting_crash;
    return 0;
  }
  vector<iovec> iov;
  bl.prepare_iov(&iov);

  auto left = len;
  auto o = off;
  size_t idx = 0;
  do {
    auto r = ::pwritev(choose_fd(buffered, write_hint),
      &iov[idx], iov.size() - idx, o);

    if (r < 0) {
      r = -errno;
      derr << __func__ << " pwritev error: " << cpp_strerror(r) << dendl;
      return r;
    }
    o += r;
    left -= r;
    if (left) {
      // skip fully processed IOVs
      while (idx < iov.size() && (size_t)r >= iov[idx].iov_len) {
        r -= iov[idx++].iov_len;
      }
      // update partially processed one if any
      if (r) {
        ceph_assert(idx < iov.size());
        ceph_assert((size_t)r < iov[idx].iov_len);
        iov[idx].iov_base = static_cast<char*>(iov[idx].iov_base) + r;
        iov[idx].iov_len -= r;
        r = 0;
      }
      ceph_assert(r == 0);
    }
  } while (left);

#ifdef HAVE_SYNC_FILE_RANGE
  if (buffered) {
    // initiate IO and wait till it completes
    auto r = ::sync_file_range(fd_buffereds[WRITE_LIFE_NOT_SET], off, len, SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER|SYNC_FILE_RANGE_WAIT_BEFORE);
    if (r < 0) {
      r = -errno;
      derr << __func__ << " sync_file_range error: " << cpp_strerror(r) << dendl;
      return r;
    }
  }
#endif