1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
2 // vim: ts=8 sw=2 smarttab
4 #include "include/compat.h"
5 #include "BootstrapRequest.h"
6 #include "CloseImageRequest.h"
7 #include "CreateImageRequest.h"
8 #include "IsPrimaryRequest.h"
9 #include "OpenImageRequest.h"
10 #include "OpenLocalImageRequest.h"
11 #include "common/debug.h"
12 #include "common/dout.h"
13 #include "common/errno.h"
14 #include "common/WorkQueue.h"
15 #include "cls/rbd/cls_rbd_client.h"
16 #include "journal/Journaler.h"
17 #include "librbd/ImageCtx.h"
18 #include "librbd/ImageState.h"
19 #include "librbd/internal.h"
20 #include "librbd/Journal.h"
21 #include "librbd/Utils.h"
22 #include "librbd/journal/Types.h"
23 #include "tools/rbd_mirror/ProgressContext.h"
24 #include "tools/rbd_mirror/ImageSync.h"
26 #define dout_context g_ceph_context
27 #define dout_subsys ceph_subsys_rbd_mirror
29 #define dout_prefix *_dout << "rbd::mirror::image_replayer::BootstrapRequest: " \
30 << this << " " << __func__
34 namespace image_replayer
{
36 using librbd::util::create_context_callback
;
37 using librbd::util::create_rados_callback
;
38 using librbd::util::unique_lock_name
;
41 BootstrapRequest
<I
>::BootstrapRequest(
42 librados::IoCtx
&local_io_ctx
,
43 librados::IoCtx
&remote_io_ctx
,
44 InstanceWatcher
<I
> *instance_watcher
,
46 const std::string
&local_image_id
,
47 const std::string
&remote_image_id
,
48 const std::string
&global_image_id
,
49 ContextWQ
*work_queue
, SafeTimer
*timer
,
51 const std::string
&local_mirror_uuid
,
52 const std::string
&remote_mirror_uuid
,
54 MirrorPeerClientMeta
*client_meta
,
57 rbd::mirror::ProgressContext
*progress_ctx
)
58 : BaseRequest("rbd::mirror::image_replayer::BootstrapRequest",
59 reinterpret_cast<CephContext
*>(local_io_ctx
.cct()), on_finish
),
60 m_local_io_ctx(local_io_ctx
), m_remote_io_ctx(remote_io_ctx
),
61 m_instance_watcher(instance_watcher
), m_local_image_ctx(local_image_ctx
),
62 m_local_image_id(local_image_id
), m_remote_image_id(remote_image_id
),
63 m_global_image_id(global_image_id
), m_work_queue(work_queue
),
64 m_timer(timer
), m_timer_lock(timer_lock
),
65 m_local_mirror_uuid(local_mirror_uuid
),
66 m_remote_mirror_uuid(remote_mirror_uuid
), m_journaler(journaler
),
67 m_client_meta(client_meta
), m_progress_ctx(progress_ctx
),
68 m_do_resync(do_resync
),
69 m_lock(unique_lock_name("BootstrapRequest::m_lock", this)) {
73 BootstrapRequest
<I
>::~BootstrapRequest() {
74 assert(m_remote_image_ctx
== nullptr);
78 bool BootstrapRequest
<I
>::is_syncing() const {
79 Mutex::Locker
locker(m_lock
);
80 return (m_image_sync
!= nullptr);
84 void BootstrapRequest
<I
>::send() {
87 get_remote_tag_class();
91 void BootstrapRequest
<I
>::cancel() {
94 Mutex::Locker
locker(m_lock
);
97 if (m_image_sync
!= nullptr) {
98 m_image_sync
->cancel();
102 template <typename I
>
103 void BootstrapRequest
<I
>::get_remote_tag_class() {
106 update_progress("GET_REMOTE_TAG_CLASS");
108 Context
*ctx
= create_context_callback
<
109 BootstrapRequest
<I
>, &BootstrapRequest
<I
>::handle_get_remote_tag_class
>(
111 m_journaler
->get_client(librbd::Journal
<>::IMAGE_CLIENT_ID
, &m_client
, ctx
);
114 template <typename I
>
115 void BootstrapRequest
<I
>::handle_get_remote_tag_class(int r
) {
116 dout(20) << ": r=" << r
<< dendl
;
119 derr
<< ": failed to retrieve remote client: " << cpp_strerror(r
) << dendl
;
124 librbd::journal::ClientData client_data
;
125 bufferlist::iterator it
= m_client
.data
.begin();
127 ::decode(client_data
, it
);
128 } catch (const buffer::error
&err
) {
129 derr
<< ": failed to decode remote client meta data: " << err
.what()
135 librbd::journal::ImageClientMeta
*client_meta
=
136 boost::get
<librbd::journal::ImageClientMeta
>(&client_data
.client_meta
);
137 if (client_meta
== nullptr) {
138 derr
<< ": unknown remote client registration" << dendl
;
143 m_remote_tag_class
= client_meta
->tag_class
;
144 dout(10) << ": remote tag class=" << m_remote_tag_class
<< dendl
;
149 template <typename I
>
150 void BootstrapRequest
<I
>::open_remote_image() {
153 update_progress("OPEN_REMOTE_IMAGE");
155 Context
*ctx
= create_context_callback
<
156 BootstrapRequest
<I
>, &BootstrapRequest
<I
>::handle_open_remote_image
>(
158 OpenImageRequest
<I
> *request
= OpenImageRequest
<I
>::create(
159 m_remote_io_ctx
, &m_remote_image_ctx
, m_remote_image_id
, false,
164 template <typename I
>
165 void BootstrapRequest
<I
>::handle_open_remote_image(int r
) {
166 dout(20) << ": r=" << r
<< dendl
;
169 derr
<< ": failed to open remote image: " << cpp_strerror(r
) << dendl
;
170 assert(m_remote_image_ctx
== nullptr);
178 template <typename I
>
179 void BootstrapRequest
<I
>::get_client() {
182 update_progress("GET_CLIENT");
184 Context
*ctx
= create_context_callback
<
185 BootstrapRequest
<I
>, &BootstrapRequest
<I
>::handle_get_client
>(
187 m_journaler
->get_client(m_local_mirror_uuid
, &m_client
, ctx
);
190 template <typename I
>
191 void BootstrapRequest
<I
>::handle_get_client(int r
) {
192 dout(20) << ": r=" << r
<< dendl
;
195 dout(10) << ": client not registered" << dendl
;
197 derr
<< ": failed to retrieve client: " << cpp_strerror(r
) << dendl
;
199 close_remote_image();
201 } else if (decode_client_meta()) {
202 // skip registration if it already exists
210 template <typename I
>
211 void BootstrapRequest
<I
>::register_client() {
214 update_progress("REGISTER_CLIENT");
216 librbd::journal::MirrorPeerClientMeta mirror_peer_client_meta
{
218 mirror_peer_client_meta
.state
= librbd::journal::MIRROR_PEER_STATE_REPLAYING
;
220 librbd::journal::ClientData client_data
{mirror_peer_client_meta
};
221 bufferlist client_data_bl
;
222 ::encode(client_data
, client_data_bl
);
224 Context
*ctx
= create_context_callback
<
225 BootstrapRequest
<I
>, &BootstrapRequest
<I
>::handle_register_client
>(
227 m_journaler
->register_client(client_data_bl
, ctx
);
230 template <typename I
>
231 void BootstrapRequest
<I
>::handle_register_client(int r
) {
232 dout(20) << ": r=" << r
<< dendl
;
235 derr
<< ": failed to register with remote journal: " << cpp_strerror(r
)
238 close_remote_image();
243 *m_client_meta
= librbd::journal::MirrorPeerClientMeta(m_local_image_id
);
244 m_client_meta
->state
= librbd::journal::MIRROR_PEER_STATE_REPLAYING
;
249 template <typename I
>
250 void BootstrapRequest
<I
>::is_primary() {
253 update_progress("OPEN_REMOTE_IMAGE");
255 Context
*ctx
= create_context_callback
<
256 BootstrapRequest
<I
>, &BootstrapRequest
<I
>::handle_is_primary
>(
258 IsPrimaryRequest
<I
> *request
= IsPrimaryRequest
<I
>::create(m_remote_image_ctx
,
263 template <typename I
>
264 void BootstrapRequest
<I
>::handle_is_primary(int r
) {
265 dout(20) << ": r=" << r
<< dendl
;
268 derr
<< ": error querying remote image primary status: " << cpp_strerror(r
)
271 close_remote_image();
276 dout(5) << ": remote image is not primary -- skipping image replay"
278 m_ret_val
= -EREMOTEIO
;
279 update_client_state();
283 if (m_local_image_id
.empty()) {
284 update_client_image();
291 template <typename I
>
292 void BootstrapRequest
<I
>::update_client_state() {
293 if (m_client_meta
->state
== librbd::journal::MIRROR_PEER_STATE_REPLAYING
) {
294 // state already set for replaying upon failover
295 close_remote_image();
300 update_progress("UPDATE_CLIENT_STATE");
302 librbd::journal::MirrorPeerClientMeta
client_meta(*m_client_meta
);
303 client_meta
.state
= librbd::journal::MIRROR_PEER_STATE_REPLAYING
;
305 librbd::journal::ClientData
client_data(client_meta
);
307 ::encode(client_data
, data_bl
);
309 Context
*ctx
= create_context_callback
<
310 BootstrapRequest
<I
>, &BootstrapRequest
<I
>::handle_update_client_state
>(
312 m_journaler
->update_client(data_bl
, ctx
);
315 template <typename I
>
316 void BootstrapRequest
<I
>::handle_update_client_state(int r
) {
317 dout(20) << ": r=" << r
<< dendl
;
319 derr
<< ": failed to update client: " << cpp_strerror(r
) << dendl
;
321 m_client_meta
->state
= librbd::journal::MIRROR_PEER_STATE_REPLAYING
;
324 close_remote_image();
327 template <typename I
>
328 void BootstrapRequest
<I
>::open_local_image() {
331 update_progress("OPEN_LOCAL_IMAGE");
333 Context
*ctx
= create_context_callback
<
334 BootstrapRequest
<I
>, &BootstrapRequest
<I
>::handle_open_local_image
>(
336 OpenLocalImageRequest
<I
> *request
= OpenLocalImageRequest
<I
>::create(
337 m_local_io_ctx
, m_local_image_ctx
, m_local_image_id
, m_work_queue
,
342 template <typename I
>
343 void BootstrapRequest
<I
>::handle_open_local_image(int r
) {
344 dout(20) << ": r=" << r
<< dendl
;
347 assert(*m_local_image_ctx
== nullptr);
348 dout(10) << ": local image missing" << dendl
;
351 } else if (r
== -EREMOTEIO
) {
352 assert(*m_local_image_ctx
== nullptr);
353 dout(10) << "local image is primary -- skipping image replay" << dendl
;
355 close_remote_image();
358 assert(*m_local_image_ctx
== nullptr);
359 derr
<< ": failed to open local image: " << cpp_strerror(r
) << dendl
;
361 close_remote_image();
365 I
*local_image_ctx
= (*m_local_image_ctx
);
367 RWLock::RLocker
snap_locker(local_image_ctx
->snap_lock
);
368 if (local_image_ctx
->journal
== nullptr) {
369 derr
<< ": local image does not support journaling" << dendl
;
375 r
= (*m_local_image_ctx
)->journal
->is_resync_requested(m_do_resync
);
377 derr
<< ": failed to check if a resync was requested" << dendl
;
385 close_remote_image();
389 if (m_client
.state
== cls::journal::CLIENT_STATE_DISCONNECTED
) {
390 dout(10) << ": client flagged disconnected -- skipping bootstrap" << dendl
;
391 // The caller is expected to detect disconnect initializing remote journal.
393 close_remote_image();
400 template <typename I
>
401 void BootstrapRequest
<I
>::unregister_client() {
403 update_progress("UNREGISTER_CLIENT");
405 m_local_image_id
= "";
406 Context
*ctx
= create_context_callback
<
407 BootstrapRequest
<I
>, &BootstrapRequest
<I
>::handle_unregister_client
>(
409 m_journaler
->unregister_client(ctx
);
412 template <typename I
>
413 void BootstrapRequest
<I
>::handle_unregister_client(int r
) {
414 dout(20) << ": r=" << r
<< dendl
;
416 derr
<< ": failed to unregister with remote journal: " << cpp_strerror(r
)
419 close_remote_image();
423 *m_client_meta
= librbd::journal::MirrorPeerClientMeta("");
427 template <typename I
>
428 void BootstrapRequest
<I
>::update_client_image() {
430 update_progress("UPDATE_CLIENT_IMAGE");
432 assert(m_local_image_id
.empty());
433 m_local_image_id
= librbd::util::generate_image_id
<I
>(m_local_io_ctx
);
435 librbd::journal::MirrorPeerClientMeta client_meta
{m_local_image_id
};
436 client_meta
.state
= librbd::journal::MIRROR_PEER_STATE_SYNCING
;
438 librbd::journal::ClientData
client_data(client_meta
);
440 ::encode(client_data
, data_bl
);
442 Context
*ctx
= create_context_callback
<
443 BootstrapRequest
<I
>, &BootstrapRequest
<I
>::handle_update_client_image
>(
445 m_journaler
->update_client(data_bl
, ctx
);
448 template <typename I
>
449 void BootstrapRequest
<I
>::handle_update_client_image(int r
) {
450 dout(20) << ": r=" << r
<< dendl
;
453 derr
<< ": failed to update client: " << cpp_strerror(r
) << dendl
;
455 close_remote_image();
460 dout(10) << ": request canceled" << dendl
;
461 m_ret_val
= -ECANCELED
;
462 close_remote_image();
466 *m_client_meta
= {m_local_image_id
};
467 m_client_meta
->state
= librbd::journal::MIRROR_PEER_STATE_SYNCING
;
468 create_local_image();
471 template <typename I
>
472 void BootstrapRequest
<I
>::create_local_image() {
474 update_progress("CREATE_LOCAL_IMAGE");
476 m_remote_image_ctx
->snap_lock
.get_read();
477 std::string image_name
= m_remote_image_ctx
->name
;
478 m_remote_image_ctx
->snap_lock
.put_read();
480 Context
*ctx
= create_context_callback
<
481 BootstrapRequest
<I
>, &BootstrapRequest
<I
>::handle_create_local_image
>(
483 CreateImageRequest
<I
> *request
= CreateImageRequest
<I
>::create(
484 m_local_io_ctx
, m_work_queue
, m_global_image_id
, m_remote_mirror_uuid
,
485 image_name
, m_local_image_id
, m_remote_image_ctx
, ctx
);
489 template <typename I
>
490 void BootstrapRequest
<I
>::handle_create_local_image(int r
) {
491 dout(20) << ": r=" << r
<< dendl
;
494 derr
<< ": failed to create local image: " << cpp_strerror(r
) << dendl
;
496 close_remote_image();
503 template <typename I
>
504 void BootstrapRequest
<I
>::get_remote_tags() {
505 if (m_client_meta
->state
== librbd::journal::MIRROR_PEER_STATE_SYNCING
) {
506 // optimization -- no need to compare remote tags if we just created
507 // the image locally or sync was interrupted
513 update_progress("GET_REMOTE_TAGS");
515 Context
*ctx
= create_context_callback
<
516 BootstrapRequest
<I
>, &BootstrapRequest
<I
>::handle_get_remote_tags
>(this);
517 m_journaler
->get_tags(m_remote_tag_class
, &m_remote_tags
, ctx
);
520 template <typename I
>
521 void BootstrapRequest
<I
>::handle_get_remote_tags(int r
) {
522 dout(20) << ": r=" << r
<< dendl
;
525 derr
<< ": failed to retrieve remote tags: " << cpp_strerror(r
) << dendl
;
532 dout(10) << ": request canceled" << dendl
;
533 m_ret_val
= -ECANCELED
;
538 // At this point, the local image was existing, non-primary, and replaying;
539 // and the remote image is primary. Attempt to link the local image's most
540 // recent tag to the remote image's tag chain.
541 uint64_t local_tag_tid
;
542 librbd::journal::TagData local_tag_data
;
543 I
*local_image_ctx
= (*m_local_image_ctx
);
545 RWLock::RLocker
snap_locker(local_image_ctx
->snap_lock
);
546 if (local_image_ctx
->journal
== nullptr) {
547 derr
<< ": local image does not support journaling" << dendl
;
553 local_tag_tid
= local_image_ctx
->journal
->get_tag_tid();
554 local_tag_data
= local_image_ctx
->journal
->get_tag_data();
555 dout(20) << ": local tag " << local_tag_tid
<< ": "
556 << local_tag_data
<< dendl
;
559 bool remote_tag_data_valid
= false;
560 librbd::journal::TagData remote_tag_data
;
561 boost::optional
<uint64_t> remote_orphan_tag_tid
=
562 boost::make_optional
<uint64_t>(false, 0U);
563 bool reconnect_orphan
= false;
565 // decode the remote tags
566 for (auto &remote_tag
: m_remote_tags
) {
567 if (local_tag_data
.predecessor
.commit_valid
&&
568 local_tag_data
.predecessor
.mirror_uuid
== m_remote_mirror_uuid
&&
569 local_tag_data
.predecessor
.tag_tid
> remote_tag
.tid
) {
570 dout(20) << ": skipping processed predecessor remote tag "
571 << remote_tag
.tid
<< dendl
;
576 bufferlist::iterator it
= remote_tag
.data
.begin();
577 ::decode(remote_tag_data
, it
);
578 remote_tag_data_valid
= true;
579 } catch (const buffer::error
&err
) {
580 derr
<< ": failed to decode remote tag " << remote_tag
.tid
<< ": "
581 << err
.what() << dendl
;
582 m_ret_val
= -EBADMSG
;
587 dout(10) << ": decoded remote tag " << remote_tag
.tid
<< ": "
588 << remote_tag_data
<< dendl
;
590 if (!local_tag_data
.predecessor
.commit_valid
) {
591 // newly synced local image (no predecessor) replays from the first tag
592 if (remote_tag_data
.mirror_uuid
!= librbd::Journal
<>::LOCAL_MIRROR_UUID
) {
593 dout(20) << ": skipping non-primary remote tag" << dendl
;
597 dout(20) << ": using initial primary remote tag" << dendl
;
601 if (local_tag_data
.mirror_uuid
== librbd::Journal
<>::ORPHAN_MIRROR_UUID
) {
602 // demotion last available local epoch
604 if (remote_tag_data
.mirror_uuid
== local_tag_data
.mirror_uuid
&&
605 remote_tag_data
.predecessor
.commit_valid
&&
606 remote_tag_data
.predecessor
.tag_tid
==
607 local_tag_data
.predecessor
.tag_tid
) {
608 // demotion matches remote epoch
610 if (remote_tag_data
.predecessor
.mirror_uuid
== m_local_mirror_uuid
&&
611 local_tag_data
.predecessor
.mirror_uuid
==
612 librbd::Journal
<>::LOCAL_MIRROR_UUID
) {
613 // local demoted and remote has matching event
614 dout(20) << ": found matching local demotion tag" << dendl
;
615 remote_orphan_tag_tid
= remote_tag
.tid
;
619 if (local_tag_data
.predecessor
.mirror_uuid
== m_remote_mirror_uuid
&&
620 remote_tag_data
.predecessor
.mirror_uuid
==
621 librbd::Journal
<>::LOCAL_MIRROR_UUID
) {
622 // remote demoted and local has matching event
623 dout(20) << ": found matching remote demotion tag" << dendl
;
624 remote_orphan_tag_tid
= remote_tag
.tid
;
629 if (remote_tag_data
.mirror_uuid
== librbd::Journal
<>::LOCAL_MIRROR_UUID
&&
630 remote_tag_data
.predecessor
.mirror_uuid
== librbd::Journal
<>::ORPHAN_MIRROR_UUID
&&
631 remote_tag_data
.predecessor
.commit_valid
&& remote_orphan_tag_tid
&&
632 remote_tag_data
.predecessor
.tag_tid
== *remote_orphan_tag_tid
) {
633 // remote promotion tag chained to remote/local demotion tag
634 dout(20) << ": found chained remote promotion tag" << dendl
;
635 reconnect_orphan
= true;
639 // promotion must follow demotion
640 remote_orphan_tag_tid
= boost::none
;
644 if (remote_tag_data_valid
&&
645 local_tag_data
.mirror_uuid
== m_remote_mirror_uuid
) {
646 dout(20) << ": local image is in clean replay state" << dendl
;
647 } else if (reconnect_orphan
) {
648 dout(20) << ": remote image was demoted/promoted" << dendl
;
650 derr
<< ": split-brain detected -- skipping image replay" << dendl
;
659 template <typename I
>
660 void BootstrapRequest
<I
>::image_sync() {
661 if (m_client_meta
->state
== librbd::journal::MIRROR_PEER_STATE_REPLAYING
) {
662 // clean replay state -- no image sync required
663 close_remote_image();
669 Mutex::Locker
locker(m_lock
);
671 m_ret_val
= -ECANCELED
;
673 assert(m_image_sync
== nullptr);
675 Context
*ctx
= create_context_callback
<
676 BootstrapRequest
<I
>, &BootstrapRequest
<I
>::handle_image_sync
>(this);
677 m_image_sync
= ImageSync
<I
>::create(
678 *m_local_image_ctx
, m_remote_image_ctx
, m_timer
, m_timer_lock
,
679 m_local_mirror_uuid
, m_journaler
, m_client_meta
, m_work_queue
,
680 m_instance_watcher
, ctx
, m_progress_ctx
);
685 update_progress("IMAGE_SYNC");
688 m_image_sync
->send();
693 dout(10) << ": request canceled" << dendl
;
694 close_remote_image();
697 template <typename I
>
698 void BootstrapRequest
<I
>::handle_image_sync(int r
) {
699 dout(20) << ": r=" << r
<< dendl
;
702 Mutex::Locker
locker(m_lock
);
704 m_image_sync
= nullptr;
707 dout(10) << ": request canceled" << dendl
;
708 m_ret_val
= -ECANCELED
;
712 derr
<< ": failed to sync remote image: " << cpp_strerror(r
) << dendl
;
717 close_remote_image();
720 template <typename I
>
721 void BootstrapRequest
<I
>::close_local_image() {
724 update_progress("CLOSE_LOCAL_IMAGE");
726 Context
*ctx
= create_context_callback
<
727 BootstrapRequest
<I
>, &BootstrapRequest
<I
>::handle_close_local_image
>(
729 CloseImageRequest
<I
> *request
= CloseImageRequest
<I
>::create(
730 m_local_image_ctx
, ctx
);
734 template <typename I
>
735 void BootstrapRequest
<I
>::handle_close_local_image(int r
) {
736 dout(20) << ": r=" << r
<< dendl
;
739 derr
<< ": error encountered closing local image: " << cpp_strerror(r
)
743 close_remote_image();
746 template <typename I
>
747 void BootstrapRequest
<I
>::close_remote_image() {
750 update_progress("CLOSE_REMOTE_IMAGE");
752 Context
*ctx
= create_context_callback
<
753 BootstrapRequest
<I
>, &BootstrapRequest
<I
>::handle_close_remote_image
>(
755 CloseImageRequest
<I
> *request
= CloseImageRequest
<I
>::create(
756 &m_remote_image_ctx
, ctx
);
760 template <typename I
>
761 void BootstrapRequest
<I
>::handle_close_remote_image(int r
) {
762 dout(20) << ": r=" << r
<< dendl
;
765 derr
<< ": error encountered closing remote image: " << cpp_strerror(r
)
772 template <typename I
>
773 bool BootstrapRequest
<I
>::decode_client_meta() {
776 librbd::journal::ClientData client_data
;
777 bufferlist::iterator it
= m_client
.data
.begin();
779 ::decode(client_data
, it
);
780 } catch (const buffer::error
&err
) {
781 derr
<< ": failed to decode client meta data: " << err
.what() << dendl
;
785 librbd::journal::MirrorPeerClientMeta
*client_meta
=
786 boost::get
<librbd::journal::MirrorPeerClientMeta
>(&client_data
.client_meta
);
787 if (client_meta
== nullptr) {
788 derr
<< ": unknown peer registration" << dendl
;
790 } else if (!client_meta
->image_id
.empty()) {
791 // have an image id -- use that to open the image
792 m_local_image_id
= client_meta
->image_id
;
795 *m_client_meta
= *client_meta
;
797 dout(20) << ": client found: image_id=" << m_local_image_id
798 << ", client_meta=" << *m_client_meta
<< dendl
;
802 template <typename I
>
803 void BootstrapRequest
<I
>::update_progress(const std::string
&description
) {
804 dout(20) << ": " << description
<< dendl
;
806 if (m_progress_ctx
) {
807 m_progress_ctx
->update_progress(description
);
811 } // namespace image_replayer
812 } // namespace mirror
815 template class rbd::mirror::image_replayer::BootstrapRequest
<librbd::ImageCtx
>;