[sheepdog] [sheepdog/sheepdog] 24ae9a: sheep: redesign get_vdis_from() with bitmap and ob...

[Hitoshi Mitake]

  Branch: refs/heads/for-142
  Home:   https://github.com/sheepdog/sheepdog
  Commit: 24ae9a574d8f1df37a2b0d5c51c4cbdaeaba60b7
      https://github.com/sheepdog/sheepdog/commit/24ae9a574d8f1df37a2b0d5c51c4cbdaeaba60b7
  Author: Hitoshi Mitake <mitake.hitoshi at lab.ntt.co.jp>
  Date:   2015-09-21 (Mon, 21 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>