[sheepdog] [sheepdog/sheepdog] 4af6f3: sheep: redesign get_vdis_from() with bitmap and ob...

[Hitoshi Mitake]

  Branch: refs/heads/for-142
  Home:   https://github.com/sheepdog/sheepdog
  Commit: 4af6f30741cffae22ff9c273f9fc2af137e4ee09
      https://github.com/sheepdog/sheepdog/commit/4af6f30741cffae22ff9c273f9fc2af137e4ee09
  Author: Hitoshi Mitake <mitake.hitoshi at lab.ntt.co.jp>
  Date:   2015-09-22 (Tue, 22 Sep 2015)

  Changed paths:
    M sheep/group.c
    M sheep/request.c

  Log Message:
  -----------
  sheep: redesign get_vdis_from() with bitmap and object reading

Current get_vdis_from() is based on SD_OP_GET_VDI_COPIES. The opcode
isn't scalable because it requires memory area whose size is linear to
a number of VDIs stored in the cluster. It cannot work well for a
cluster which has many VDIs.

This commit fixes the problem with redesign the function with bitmap
synchronization (SD_OP_READ_VDIS and SD_OP_READ_DEL_VDIS) and ordinal
inode object reading (SD_OP_READ_OBJ).

Fixes https://github.com/sheepdog/sheepdog/issues/142

Signed-off-by: Hitoshi Mitake <mitake.hitoshi at lab.ntt.co.jp>