diff mbox

[v2,4/4] replay: introduce block devices record/replay

Message ID 20160210091323.10024.5684.stgit@PASHA-ISP (mailing list archive)
State New, archived
Headers show

Commit Message

Pavel Dovgalyuk Feb. 10, 2016, 9:13 a.m. UTC 
This patch introduces a set of functions that implement recording
and replaying of block devices' operations. These functions form a thin
layer between blk_aio_ functions and replay subsystem.
All asynchronous block requests are added to the queue to be processed
at deterministically invoked record/replay checkpoints.
Queue is flushed at checkpoints and information about processed requests
is recorded to the log. In replay phase the queue is matched with
events read from the log. Therefore block devices requests are processed
deterministically.

Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
---
 block/block-backend.c    |   54 ++++++++++++--
 include/sysemu/replay.h  |   30 ++++++++
 replay/Makefile.objs     |    1 
 replay/replay-block.c    |  172 ++++++++++++++++++++++++++++++++++++++++++++++
 replay/replay-events.c   |   51 ++++++++++++++
 replay/replay-internal.h |   24 ++++++
 stubs/replay.c           |   50 +++++++++++++
 7 files changed, 372 insertions(+), 10 deletions(-)
 create mode 100755 replay/replay-block.c

Comments

Stefan Hajnoczi Feb. 11, 2016, 9:56 a.m. UTC | #1 
On Wed, Feb 10, 2016 at 12:13:23PM +0300, Pavel Dovgalyuk wrote:
> @@ -784,7 +798,11 @@ BlockAIOCB *blk_aio_flush(BlockBackend *blk,
>          return blk_abort_aio_request(blk, cb, opaque, -ENOMEDIUM);
>      }
>  
> -    return bdrv_aio_flush(blk->bs, cb, opaque);
> +    if (replay_mode == REPLAY_MODE_NONE) {
> +        return bdrv_aio_flush(blk->bs, cb, opaque);
> +    } else {
> +        return replay_aio_flush(blk->bs, cb, opaque);
> +    }
>  }

I am only looking at this patch in isolation and am not familiar with
the record/replay work, but these changes appear invasive.  In order for
record/replay to keep working in the future, everyone touching block
layer code must be familiar with the principles of how record/replay
works.  This patch does not include documentation.

Can you point me to documentation that explains the how record replay
works?

Thanks,
Stefan
Pavel Dovgalyuk Feb. 11, 2016, 1:52 p.m. UTC | #2 
> From: Stefan Hajnoczi [mailto:stefanha@redhat.com]
> On Wed, Feb 10, 2016 at 12:13:23PM +0300, Pavel Dovgalyuk wrote:
> > @@ -784,7 +798,11 @@ BlockAIOCB *blk_aio_flush(BlockBackend *blk,
> >          return blk_abort_aio_request(blk, cb, opaque, -ENOMEDIUM);
> >      }
> >
> > -    return bdrv_aio_flush(blk->bs, cb, opaque);
> > +    if (replay_mode == REPLAY_MODE_NONE) {
> > +        return bdrv_aio_flush(blk->bs, cb, opaque);
> > +    } else {
> > +        return replay_aio_flush(blk->bs, cb, opaque);
> > +    }
> >  }
> 
> I am only looking at this patch in isolation and am not familiar with
> the record/replay work, but these changes appear invasive.  In order for
> record/replay to keep working in the future, everyone touching block
> layer code must be familiar with the principles of how record/replay
> works.  This patch does not include documentation.

We've already discussed it with Kevin.
He proposes adding new block driver for record/replay.

> Can you point me to documentation that explains the how record replay
> works?

There is some information about it in docs/replay.txt and in
http://wiki.qemu.org/Features/record-replay

Pavel Dovgalyuk
Stefan Hajnoczi Feb. 11, 2016, 2:51 p.m. UTC | #3 
On Thu, Feb 11, 2016 at 04:52:42PM +0300, Pavel Dovgalyuk wrote:
> > From: Stefan Hajnoczi [mailto:stefanha@redhat.com]
> > On Wed, Feb 10, 2016 at 12:13:23PM +0300, Pavel Dovgalyuk wrote:
> > > @@ -784,7 +798,11 @@ BlockAIOCB *blk_aio_flush(BlockBackend *blk,
> > >          return blk_abort_aio_request(blk, cb, opaque, -ENOMEDIUM);
> > >      }
> > >
> > > -    return bdrv_aio_flush(blk->bs, cb, opaque);
> > > +    if (replay_mode == REPLAY_MODE_NONE) {
> > > +        return bdrv_aio_flush(blk->bs, cb, opaque);
> > > +    } else {
> > > +        return replay_aio_flush(blk->bs, cb, opaque);
> > > +    }
> > >  }
> > 
> > I am only looking at this patch in isolation and am not familiar with
> > the record/replay work, but these changes appear invasive.  In order for
> > record/replay to keep working in the future, everyone touching block
> > layer code must be familiar with the principles of how record/replay
> > works.  This patch does not include documentation.
> 
> We've already discussed it with Kevin.
> He proposes adding new block driver for record/replay.
> 
> > Can you point me to documentation that explains the how record replay
> > works?
> 
> There is some information about it in docs/replay.txt and in
> http://wiki.qemu.org/Features/record-replay

I was thinking about developer documentation.  A feature like this is
"cross-cutting" - it affects many components.  There should be
documentation that explains the semantics so everyone modifying code can
follow the rules to keep record/replay working.

Live migration is similar in that it touches many components.  The
docs/migration.txt file explains the APIs and general idea.  It
communicates the assumptions, limitations, and requirements that live
migration imposes.  Many QEMU developers understand migration basics and
keep them in mind during code review.  This way we can prevent most (but
not all) migration breakage.

Record/replay should aim for the same level of education/awareness,
otherwise the feature will break and bitrot.

The alternative is to implement it in a way that isn't invasive.  Then
other developers don't need to understand how it works.  Maybe
implementing it in a block driver can achieve this.

Stefan
diff mbox

Patch

diff --git a/block/block-backend.c b/block/block-backend.c
index ebdf78a..1765369 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -17,6 +17,7 @@ 
 #include "block/throttle-groups.h"
 #include "sysemu/blockdev.h"
 #include "sysemu/sysemu.h"
+#include "sysemu/replay.h"
 #include "qapi-event.h"
 
 /* Number of coroutines to reserve per attached device model */
@@ -688,7 +689,7 @@  BlockAIOCB *blk_abort_aio_request(BlockBackend *blk,
 
     bh = aio_bh_new(blk_get_aio_context(blk), error_callback_bh, acb);
     acb->bh = bh;
-    qemu_bh_schedule(bh);
+    replay_bh_schedule_event(bh);
 
     return &acb->common;
 }
@@ -702,8 +703,13 @@  BlockAIOCB *blk_aio_write_zeroes(BlockBackend *blk, int64_t sector_num,
         return blk_abort_aio_request(blk, cb, opaque, ret);
     }
 
-    return bdrv_aio_write_zeroes(blk->bs, sector_num, nb_sectors, flags,
-                                 cb, opaque);
+    if (replay_mode == REPLAY_MODE_NONE) {
+        return bdrv_aio_write_zeroes(blk->bs, sector_num, nb_sectors, flags,
+                                     cb, opaque);
+    } else {
+        return replay_aio_write_zeroes(blk->bs, sector_num, nb_sectors, flags,
+                                       cb, opaque);
+    }
 }
 
 int blk_pread(BlockBackend *blk, int64_t offset, void *buf, int count)
@@ -762,7 +768,11 @@  BlockAIOCB *blk_aio_readv(BlockBackend *blk, int64_t sector_num,
         return blk_abort_aio_request(blk, cb, opaque, ret);
     }
 
-    return bdrv_aio_readv(blk->bs, sector_num, iov, nb_sectors, cb, opaque);
+    if (replay_mode == REPLAY_MODE_NONE) {
+        return bdrv_aio_readv(blk->bs, sector_num, iov, nb_sectors, cb, opaque);
+    } else {
+        return replay_aio_readv(blk->bs, sector_num, iov, nb_sectors, cb, opaque);
+    }
 }
 
 BlockAIOCB *blk_aio_writev(BlockBackend *blk, int64_t sector_num,
@@ -774,7 +784,11 @@  BlockAIOCB *blk_aio_writev(BlockBackend *blk, int64_t sector_num,
         return blk_abort_aio_request(blk, cb, opaque, ret);
     }
 
-    return bdrv_aio_writev(blk->bs, sector_num, iov, nb_sectors, cb, opaque);
+    if (replay_mode == REPLAY_MODE_NONE) {
+        return bdrv_aio_writev(blk->bs, sector_num, iov, nb_sectors, cb, opaque);
+    } else {
+        return replay_aio_writev(blk->bs, sector_num, iov, nb_sectors, cb, opaque);
+    }
 }
 
 BlockAIOCB *blk_aio_flush(BlockBackend *blk,
@@ -784,7 +798,11 @@  BlockAIOCB *blk_aio_flush(BlockBackend *blk,
         return blk_abort_aio_request(blk, cb, opaque, -ENOMEDIUM);
     }
 
-    return bdrv_aio_flush(blk->bs, cb, opaque);
+    if (replay_mode == REPLAY_MODE_NONE) {
+        return bdrv_aio_flush(blk->bs, cb, opaque);
+    } else {
+        return replay_aio_flush(blk->bs, cb, opaque);
+    }
 }
 
 BlockAIOCB *blk_aio_discard(BlockBackend *blk,
@@ -796,17 +814,29 @@  BlockAIOCB *blk_aio_discard(BlockBackend *blk,
         return blk_abort_aio_request(blk, cb, opaque, ret);
     }
 
-    return bdrv_aio_discard(blk->bs, sector_num, nb_sectors, cb, opaque);
+    if (replay_mode == REPLAY_MODE_NONE) {
+        return bdrv_aio_discard(blk->bs, sector_num, nb_sectors, cb, opaque);
+    } else {
+        return replay_aio_discard(blk->bs, sector_num, nb_sectors, cb, opaque);
+    }
 }
 
 void blk_aio_cancel(BlockAIOCB *acb)
 {
-    bdrv_aio_cancel(acb);
+    if (replay_mode == REPLAY_MODE_NONE) {
+        bdrv_aio_cancel(acb);
+    } else {
+        replay_aio_cancel(acb);
+    }
 }
 
 void blk_aio_cancel_async(BlockAIOCB *acb)
 {
-    bdrv_aio_cancel_async(acb);
+    if (replay_mode == REPLAY_MODE_NONE) {
+        bdrv_aio_cancel_async(acb);
+    } else {
+        replay_aio_cancel(acb);
+    }
 }
 
 int blk_aio_multiwrite(BlockBackend *blk, BlockRequest *reqs, int num_reqs)
@@ -839,7 +869,11 @@  BlockAIOCB *blk_aio_ioctl(BlockBackend *blk, unsigned long int req, void *buf,
         return blk_abort_aio_request(blk, cb, opaque, -ENOMEDIUM);
     }
 
-    return bdrv_aio_ioctl(blk->bs, req, buf, cb, opaque);
+    if (replay_mode == REPLAY_MODE_NONE) {
+        return bdrv_aio_ioctl(blk->bs, req, buf, cb, opaque);
+    } else {
+        return replay_aio_ioctl(blk->bs, req, buf, cb, opaque);
+    }
 }
 
 int blk_co_discard(BlockBackend *blk, int64_t sector_num, int nb_sectors)
diff --git a/include/sysemu/replay.h b/include/sysemu/replay.h
index c879231..75ad4aa 100644
--- a/include/sysemu/replay.h
+++ b/include/sysemu/replay.h
@@ -17,6 +17,8 @@ 
 #include "qapi-types.h"
 #include "qapi/error.h"
 #include "qemu/typedefs.h"
+#include "block/aio.h"
+#include "block/block.h"
 
 /* replay clock kinds */
 enum ReplayClockKind {
@@ -125,6 +127,34 @@  void replay_register_char_driver(struct CharDriverState *chr);
 /*! Saves write to char device event to the log */
 void replay_chr_be_write(struct CharDriverState *s, uint8_t *buf, int len);
 
+/* Block devices */
+
+/*! Asynchronous read function. Adds read request to the queue. */
+BlockAIOCB *replay_aio_readv(BlockDriverState *bs, int64_t sector_num,
+                             QEMUIOVector *iov, int nb_sectors,
+                             BlockCompletionFunc *cb, void *opaque);
+/*! Asynchronous write function. Adds write request to the queue. */
+BlockAIOCB *replay_aio_writev(BlockDriverState *bs, int64_t sector_num,
+                              QEMUIOVector *iov, int nb_sectors,
+                              BlockCompletionFunc *cb, void *opaque);
+/*! Asynchronous write zeroes function. Adds this request to the queue. */
+BlockAIOCB *replay_aio_write_zeroes(BlockDriverState *bs, int64_t sector_num,
+                                    int nb_sectors, BdrvRequestFlags flags,
+                                    BlockCompletionFunc *cb, void *opaque);
+/*! Asynchronous flush function. Adds flush request to the queue. */
+BlockAIOCB *replay_aio_flush(BlockDriverState *bs,
+                             BlockCompletionFunc *cb, void *opaque);
+/*! Asynchronous discard function. Adds discard request to the queue. */
+BlockAIOCB *replay_aio_discard(BlockDriverState *bs, int64_t sector_num,
+                               int nb_sectors, BlockCompletionFunc *cb,
+                               void *opaque);
+/*! Asynchronous ioctl function. Adds ioctl request to the queue. */
+BlockAIOCB *replay_aio_ioctl(BlockDriverState *bs, unsigned long int req, void *buf,
+                             BlockCompletionFunc *cb, void *opaque);
+/*! Cancels pending asynchronous IO request. */
+void replay_aio_cancel(BlockAIOCB *acb);
+
+
 /* Other data */
 
 /*! Writes or reads integer value to/from replay log. */
diff --git a/replay/Makefile.objs b/replay/Makefile.objs
index 70e5572..050c0ea 100644
--- a/replay/Makefile.objs
+++ b/replay/Makefile.objs
@@ -4,3 +4,4 @@  common-obj-y += replay-events.o
 common-obj-y += replay-time.o
 common-obj-y += replay-input.o
 common-obj-y += replay-char.o
+common-obj-y += replay-block.o
diff --git a/replay/replay-block.c b/replay/replay-block.c
new file mode 100755
index 0000000..f927580
--- /dev/null
+++ b/replay/replay-block.c
@@ -0,0 +1,172 @@ 
+/*
+ * replay-block.c
+ *
+ * Copyright (c) 2010-2016 Institute for System Programming
+ *                         of the Russian Academy of Sciences.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+#include "sysemu/replay.h"
+#include "sysemu/block-backend.h"
+#include "replay-internal.h"
+
+typedef struct ReplayAIOCB {
+    BlockAIOCB common;
+    BlockRequest req;
+    ReplayAsyncEventKind kind;
+} ReplayAIOCB;
+
+static const AIOCBInfo replay_aiocb_info = {
+    .aiocb_size   = sizeof(ReplayAIOCB),
+    .cancel_async = replay_aio_cancel
+};
+
+static ReplayAIOCB *replay_aio_create(ReplayAsyncEventKind kind,
+                                      BlockDriverState *bs,
+                                      BlockCompletionFunc *cb, void *opaque)
+{
+    ReplayAIOCB *acb = g_malloc0(sizeof(*acb));
+    acb->kind = kind;
+    /* Make correct AIOCB to return to the caller */
+    acb->common.aiocb_info = &replay_aiocb_info;
+    acb->common.bs = bs;
+    acb->common.cb = cb;
+    acb->common.opaque = opaque;
+    acb->common.refcnt = 1;
+    acb->req.error = -EINPROGRESS;
+    return acb;
+}
+
+BlockAIOCB *replay_aio_readv(BlockDriverState *bs, int64_t sector_num,
+                             QEMUIOVector *iov, int nb_sectors,
+                             BlockCompletionFunc *cb, void *opaque)
+{
+    ReplayAIOCB *acb = replay_aio_create(REPLAY_ASYNC_EVENT_BLOCK_READV,
+                                         bs, cb, opaque);
+    acb->req.sector = sector_num;
+    acb->req.nb_sectors = nb_sectors;
+    acb->req.qiov = iov;
+    replay_add_event(REPLAY_ASYNC_EVENT_BLOCK_READV, acb, NULL, 0);
+
+    return &acb->common;
+}
+
+void replay_event_block_readv_run(void *opaque)
+{
+    ReplayAIOCB *acb = opaque;
+    bdrv_aio_readv(acb->common.bs, acb->req.sector, acb->req.qiov,
+                   acb->req.nb_sectors, acb->common.cb,
+                   acb->common.opaque);
+    blk_drain_all();
+}
+
+BlockAIOCB *replay_aio_writev(BlockDriverState *bs, int64_t sector_num,
+                              QEMUIOVector *iov, int nb_sectors,
+                              BlockCompletionFunc *cb, void *opaque)
+{
+    ReplayAIOCB *acb = replay_aio_create(REPLAY_ASYNC_EVENT_BLOCK_WRITEV,
+                                         bs, cb, opaque);
+    acb->req.sector = sector_num;
+    acb->req.nb_sectors = nb_sectors;
+    acb->req.qiov = iov;
+    replay_add_event(REPLAY_ASYNC_EVENT_BLOCK_WRITEV, acb, NULL, 0);
+
+    return &acb->common;
+}
+
+void replay_event_block_writev_run(void *opaque)
+{
+    ReplayAIOCB *acb = opaque;
+    bdrv_aio_writev(acb->common.bs, acb->req.sector, acb->req.qiov,
+                    acb->req.nb_sectors, acb->common.cb,
+                    acb->common.opaque);
+    blk_drain_all();
+}
+
+BlockAIOCB *replay_aio_write_zeroes(BlockDriverState *bs, int64_t sector_num,
+                                    int nb_sectors, BdrvRequestFlags flags,
+                                    BlockCompletionFunc *cb, void *opaque)
+{
+    ReplayAIOCB *acb = replay_aio_create(REPLAY_ASYNC_EVENT_BLOCK_WRITE_ZEROES,
+                                         bs, cb, opaque);
+    acb->req.sector = sector_num;
+    acb->req.nb_sectors = nb_sectors;
+    acb->req.flags = flags;
+    replay_add_event(REPLAY_ASYNC_EVENT_BLOCK_WRITE_ZEROES, acb, NULL, 0);
+
+    return &acb->common;
+}
+
+void replay_event_block_write_zeroes_run(void *opaque)
+{
+    ReplayAIOCB *acb = opaque;
+    bdrv_aio_write_zeroes(acb->common.bs, acb->req.sector, acb->req.nb_sectors,
+                          acb->req.flags, acb->common.cb, acb->common.opaque);
+    blk_drain_all();
+}
+
+BlockAIOCB *replay_aio_flush(BlockDriverState *bs,
+                             BlockCompletionFunc *cb, void *opaque)
+{
+    ReplayAIOCB *acb = replay_aio_create(REPLAY_ASYNC_EVENT_BLOCK_FLUSH,
+                                         bs, cb, opaque);
+    replay_add_event(REPLAY_ASYNC_EVENT_BLOCK_FLUSH, acb, NULL, 0);
+
+    return &acb->common;
+}
+
+void replay_event_block_flush_run(void *opaque)
+{
+    ReplayAIOCB *acb = opaque;
+    bdrv_aio_flush(acb->common.bs, acb->common.cb, acb->common.opaque);
+    blk_drain_all();
+}
+
+void replay_aio_cancel(BlockAIOCB *acb)
+{
+    ReplayAIOCB *racb = container_of(acb, ReplayAIOCB, common);;
+    replay_remove_event(racb->kind, acb, NULL, 0);
+}
+
+BlockAIOCB *replay_aio_discard(BlockDriverState *bs, int64_t sector_num,
+                               int nb_sectors, BlockCompletionFunc *cb,
+                               void *opaque)
+{
+    ReplayAIOCB *acb = replay_aio_create(REPLAY_ASYNC_EVENT_BLOCK_DISCARD,
+                                         bs, cb, opaque);
+    acb->req.sector = sector_num;
+    acb->req.nb_sectors = nb_sectors;
+    replay_add_event(REPLAY_ASYNC_EVENT_BLOCK_DISCARD, acb, NULL, 0);
+
+    return &acb->common;
+}
+
+void replay_event_block_discard_run(void *opaque)
+{
+    ReplayAIOCB *acb = opaque;
+    bdrv_aio_discard(acb->common.bs, acb->req.sector, acb->req.nb_sectors,
+                     acb->common.cb, acb->common.opaque);
+    blk_drain_all();
+}
+
+BlockAIOCB *replay_aio_ioctl(BlockDriverState *bs, unsigned long int req, void *buf,
+                             BlockCompletionFunc *cb, void *opaque)
+{
+    ReplayAIOCB *acb = replay_aio_create(REPLAY_ASYNC_EVENT_BLOCK_IOCTL,
+                                         bs, cb, opaque);
+    acb->req.req = req;
+    acb->req.buf = buf;
+    replay_add_event(REPLAY_ASYNC_EVENT_BLOCK_IOCTL, acb, NULL, 0);
+
+    return &acb->common;
+}
+
+void replay_event_block_ioctl_run(void *opaque)
+{
+    ReplayAIOCB *acb = opaque;
+    bdrv_aio_ioctl(acb->common.bs, acb->req.req, acb->req.buf,
+                   acb->common.cb, acb->common.opaque);
+    blk_drain_all();
+}
diff --git a/replay/replay-events.c b/replay/replay-events.c
index 59d467f..14aca62 100644
--- a/replay/replay-events.c
+++ b/replay/replay-events.c
@@ -51,6 +51,24 @@  static void replay_run_event(Event *event)
     case REPLAY_ASYNC_EVENT_CHAR:
         replay_event_char_run(event->opaque);
         break;
+    case REPLAY_ASYNC_EVENT_BLOCK_READV:
+        replay_event_block_readv_run(event->opaque);
+        break;
+    case REPLAY_ASYNC_EVENT_BLOCK_WRITEV:
+        replay_event_block_writev_run(event->opaque);
+        break;
+    case REPLAY_ASYNC_EVENT_BLOCK_WRITE_ZEROES:
+        replay_event_block_write_zeroes_run(event->opaque);
+        break;
+    case REPLAY_ASYNC_EVENT_BLOCK_FLUSH:
+        replay_event_block_flush_run(event->opaque);
+        break;
+    case REPLAY_ASYNC_EVENT_BLOCK_DISCARD:
+        replay_event_block_discard_run(event->opaque);
+        break;
+    case REPLAY_ASYNC_EVENT_BLOCK_IOCTL:
+        replay_event_block_ioctl_run(event->opaque);
+        break;
     default:
         error_report("Replay: invalid async event ID (%d) in the queue",
                     event->event_kind);
@@ -133,6 +151,24 @@  void replay_add_event(ReplayAsyncEventKind event_kind,
     replay_mutex_unlock();
 }
 
+void replay_remove_event(ReplayAsyncEventKind event_kind,
+                         void *opaque,
+                         void *opaque2, uint64_t id)
+{
+    Event *event;
+    replay_mutex_lock();
+    QTAILQ_FOREACH(event, &events_list, events) {
+        if (event->event_kind == event_kind
+            && event->opaque == opaque
+            && event->opaque2 == opaque2
+            && event->id == id) {
+            QTAILQ_REMOVE(&events_list, event, events);
+            break;
+        }
+    }
+    replay_mutex_unlock();
+}
+
 void replay_bh_schedule_event(QEMUBH *bh)
 {
     if (replay_mode != REPLAY_MODE_NONE) {
@@ -174,6 +210,13 @@  static void replay_save_event(Event *event, int checkpoint)
         case REPLAY_ASYNC_EVENT_CHAR:
             replay_event_char_save(event->opaque);
             break;
+        case REPLAY_ASYNC_EVENT_BLOCK_READV:
+        case REPLAY_ASYNC_EVENT_BLOCK_WRITEV:
+        case REPLAY_ASYNC_EVENT_BLOCK_WRITE_ZEROES:
+        case REPLAY_ASYNC_EVENT_BLOCK_FLUSH:
+        case REPLAY_ASYNC_EVENT_BLOCK_DISCARD:
+        case REPLAY_ASYNC_EVENT_BLOCK_IOCTL:
+            break;
         default:
             error_report("Unknown ID %d of replay event", read_event_kind);
             exit(1);
@@ -232,6 +275,14 @@  static Event *replay_read_event(int checkpoint)
         event->event_kind = read_event_kind;
         event->opaque = replay_event_char_read();
         return event;
+    case REPLAY_ASYNC_EVENT_BLOCK_READV:
+    case REPLAY_ASYNC_EVENT_BLOCK_WRITEV:
+    case REPLAY_ASYNC_EVENT_BLOCK_WRITE_ZEROES:
+    case REPLAY_ASYNC_EVENT_BLOCK_FLUSH:
+    case REPLAY_ASYNC_EVENT_BLOCK_DISCARD:
+    case REPLAY_ASYNC_EVENT_BLOCK_IOCTL:
+        /* search in the queue */
+        break;
     default:
         error_report("Unknown ID %d of replay event", read_event_kind);
         exit(1);
diff --git a/replay/replay-internal.h b/replay/replay-internal.h
index 34eee5b..8f705d1 100644
--- a/replay/replay-internal.h
+++ b/replay/replay-internal.h
@@ -47,6 +47,12 @@  enum ReplayAsyncEventKind {
     REPLAY_ASYNC_EVENT_INPUT,
     REPLAY_ASYNC_EVENT_INPUT_SYNC,
     REPLAY_ASYNC_EVENT_CHAR,
+    REPLAY_ASYNC_EVENT_BLOCK_READV,
+    REPLAY_ASYNC_EVENT_BLOCK_WRITEV,
+    REPLAY_ASYNC_EVENT_BLOCK_WRITE_ZEROES,
+    REPLAY_ASYNC_EVENT_BLOCK_FLUSH,
+    REPLAY_ASYNC_EVENT_BLOCK_DISCARD,
+    REPLAY_ASYNC_EVENT_BLOCK_IOCTL,
     REPLAY_ASYNC_COUNT
 };
 
@@ -131,6 +137,9 @@  void replay_read_events(int checkpoint);
 /*! Adds specified async event to the queue */
 void replay_add_event(ReplayAsyncEventKind event_kind, void *opaque,
                       void *opaque2, uint64_t id);
+/*! Removes specified async event from the queue */
+void replay_remove_event(ReplayAsyncEventKind event_kind,
+                         void *opaque, void *opaque2, uint64_t id);
 
 /* Input events */
 
@@ -152,4 +161,19 @@  void replay_event_char_save(void *opaque);
 /*! Reads char event from the file. */
 void *replay_event_char_read(void);
 
+/* Block devices */
+
+/*! Called to run block device readv event. */
+void replay_event_block_readv_run(void *opaque);
+/*! Called to run block device writev event. */
+void replay_event_block_writev_run(void *opaque);
+/*! Called to run block device write zeroes event. */
+void replay_event_block_write_zeroes_run(void *opaque);
+/*! Called to run block device flush event. */
+void replay_event_block_flush_run(void *opaque);
+/*! Called to run block device discard event. */
+void replay_event_block_discard_run(void *opaque);
+/*! Called to run block device ioctl event. */
+void replay_event_block_ioctl_run(void *opaque);
+
 #endif
diff --git a/stubs/replay.c b/stubs/replay.c
index 00ca01f..635e7dd 100644
--- a/stubs/replay.c
+++ b/stubs/replay.c
@@ -1,6 +1,7 @@ 
 #include "qemu/osdep.h"
 #include "sysemu/replay.h"
 #include "sysemu/sysemu.h"
+#include "sysemu/block-backend.h"
 
 ReplayMode replay_mode;
 
@@ -29,3 +30,52 @@  bool replay_events_enabled(void)
 void replay_finish(void)
 {
 }
+
+BlockAIOCB *replay_aio_readv(BlockDriverState *bs, int64_t sector_num,
+                             QEMUIOVector *iov, int nb_sectors,
+                             BlockCompletionFunc *cb, void *opaque)
+{
+    return NULL;
+}
+
+BlockAIOCB *replay_aio_writev(BlockDriverState *bs, int64_t sector_num,
+                              QEMUIOVector *iov, int nb_sectors,
+                              BlockCompletionFunc *cb, void *opaque)
+{
+    return NULL;
+}
+
+BlockAIOCB *replay_aio_flush(BlockDriverState *bs,
+                             BlockCompletionFunc *cb, void *opaque)
+{
+    return NULL;
+}
+
+BlockAIOCB *replay_aio_discard(BlockDriverState *bs,
+                               int64_t sector_num, int nb_sectors,
+                               BlockCompletionFunc *cb, void *opaque)
+{
+    return NULL;
+}
+
+BlockAIOCB *replay_aio_ioctl(BlockDriverState *bs, unsigned long int req, void *buf,
+                             BlockCompletionFunc *cb, void *opaque)
+{
+    return NULL;
+}
+
+BlockAIOCB *replay_aio_write_zeroes(BlockDriverState *bs, int64_t sector_num,
+                                    int nb_sectors, BdrvRequestFlags flags,
+                                    BlockCompletionFunc *cb, void *opaque)
+{
+    return NULL;
+}
+
+void replay_aio_cancel(BlockAIOCB *acb)
+{
+}
+
+void replay_bh_schedule_event(QEMUBH *bh)
+{
+    qemu_bh_schedule(bh);
+}