rgw: rgw_rados: set_attrs now sets the same time for BI & object

[theanalyst]

RGWRados::set_attrs() used to set slightly different mtimes for the
object and in the bucket dir entry as we do an object write and set the
time at bucket index as the time at that point. Fix this by using the
setting the same mtime for the object as well.

Fixes: http://tracker.ceph.com/issues/21200
Signed-off-by: Abhishek Lekshmanan abhishek@suse.com

[theanalyst]

currently used #17395 for testing this (eg,. as reported in http://tracker.ceph.com/issues/21200)

[yehudasa]

lgtm

[yuriw]

http://pulpito.front.sepia.ceph.com:80/yuriw-2017-09-07_18:41:40-rgw-wip-yuri-testing2-2017-09-07-1717-distro-basic-smithi/

http://pulpito.ceph.com/yuriw-2017-09-07_22:59:41-rgw-wip-yuri-testing2-2017-09-07-1717-distro-basic-smithi/

[xxcs]

Recently, I have encountered a problem:
     1. Operation steps:
         a) Create a bucket bucket01
         b) Set multi-version properties for bucket01
         c) Upload the object to bucket01
         d) Set custom properties for the current object (mainly call RGWRados::set_attrs)
         e) Set the life cycle of the bucket (for current and historical versions)
     2. Phenomenon:
         a) The historical version is correct and can be deleted
         b) The current version is not operating correctly, there is no change (normally a delete tag version should be added)
      3. Root cause of the problem:
         a) The data mtime of the current object is inconsistent with the metadata mtime (rgw_lc.cc:RGWLC::bucket_lc_process, "if (state->mtime != obj_iter->meta.mtime)//Check mtime again to avoid delete a recently update object As much as possible")
         b) The reason for causing a) is that there is a problem in calling RGWRados::set_attrs
     4. Solve the problem:
         a) Refer to RGWRados::Object::Write::write_meta, add set_olh(obj_ctx, bucket_info, obj, false, NULL, 0, real_time(), false) after calling index_op.complete
         b) After the modification, it is found that versioned_epoch will jump (next versioned_epoch = current versioned_epoch + 2),
        c) Solve the problem 4.b). Get obj's versioned_epoch (via cls_bucket_list), then call set_olh(obj_ctx, bucket_info, obj, false, NULL, versioned_epoch, real_time(), false)
      5. Purpose:
          a) Confirm that 2.b) is a problem or not
          b) confirm the purpose of "Check mtime again to avoid delete a recently update object as much as possible"（I guess the inconsistency should happen in the process of uploading objects.）
          c) Confirm that the idea of ​​4 is correct
          d) Confirm a better solution to replace the cls_bucket_list in 4.c)