# btrace /dev/sdb | grep -e C -e D
...
  8,16   2     8181    14.332490566     0  C   R 13245353728 + 32 [0]
  8,16   2     8182    14.332500741   184  D  FN [kworker/2:1H]
  8,16   2     8184    14.342115004     0  C   R 13245353416 + 8 [0]
  8,16   2     8185    14.342124247   184  D  FN [kworker/2:1H]
  8,16   2     8187    14.343305520     0  C   R 13245353432 + 280 [0]
  8,16   2     8188    14.343323324   184  D  FN [kworker/2:1H]
  8,16   2     8189    14.343325042   184  D   N 0 [kworker/2:1H]
  8,16   2     8190    14.343327609   184  D   R 13245353712 + 16 [kworker/2:1H]
  8,16   2     8192    14.343331641    21  C   N [0]
  8,16   2     8193    14.343340561   184  D   R 13245353712 + 16 [kworker/2:1H]
  8,16   2     8195    14.926692788     0  C  FN 0 [0]
  8,16   2     8196    14.926717389   184  D  WS 2088 + 6 [kworker/2:1H]
  8,16   2     8197    14.926722808   184  D   R 13245353712 + 16 [kworker/2:1H]
  8,16   2     8198    14.926725847   184  D   R 13245353760 + 224 [kworker/2:1H]
  8,16   2     8199    14.927051763     0  C  WS 2088 + 6 [0]
  8,16   2     8200    14.927062177   184  D  FN [kworker/2:1H]
  8,16   2     8202    14.930107334     0  C   R 13245353760 + 224 [0]
  8,16   2     8203    14.930139840   184  D  FN [kworker/2:1H]
  8,16   2     8205    14.951366460     0  C   R 13245353712 + 16 [0]
  8,16   2     8206    14.951388776   184  D  FN [kworker/2:1H]
  8,16   2     8207    14.994567563     0  C  FN 0 [0]
  8,16   2     8208    14.994571321     0  C  WS 2088 [0]
  8,16   2     8223    15.979176780   513  D  WS 13245344904 + 24 [md2_raid5]
  8,16   2     8739    15.979418015   513  D  WS 13245347840 + 1024 [md2_raid5]
  8,16   2     9221    15.979728531    21  C  WS 13245344904 + 24 [0]
...