Merge remote-tracking branch 'remotes/kevin/tags/for-upstream' into staging

Block layer patches

# gpg: Signature made Wed 06 Sep 2017 14:44:41 BST
# gpg:                using RSA key 0x7F09B272C88F2FD6
# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>"
# Primary key fingerprint: DC3D EB15 9A9A F95D 3D74  56FE 7F09 B272 C88F 2FD6

* remotes/kevin/tags/for-upstream:
  qcow2: move qcow2_store_persistent_dirty_bitmaps() before cache flushing
  qemu-iotests: add 184 for throttle filter driver
  block: add throttle block filter driver
  block: convert ThrottleGroup to object with QOM
  block: tidy ThrottleGroupMember initializations
  block: add aio_context field in ThrottleGroupMember
  block: move ThrottleGroup membership to ThrottleGroupMember
  block: document semantics of bdrv_co_preadv|pwritev
  qcow: Check failure of bdrv_getlength() and bdrv_truncate()
  qcow: Change signature of get_cluster_offset()
  block: add default implementations for bdrv_co_get_block_status()
  block: remove bdrv_truncate callback in blkdebug
  block: remove unused bdrv_media_changed
  block: pass bdrv_* methods to bs->file by default in block filters

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

26 files changed, 1886 insertions, 453 deletions

diff --git a/block.c b/block.c
index b749bd6404..6dd47e414e 100644
--- a/block.c
+++ b/block.c
@@ -496,6 +496,8 @@ int bdrv_probe_blocksizes(BlockDriverState *bs, BlockSizes *bsz)
 
     if (drv && drv->bdrv_probe_blocksizes) {
         return drv->bdrv_probe_blocksizes(bs, bsz);
+    } else if (drv && drv->is_filter && bs->file) {
+        return bdrv_probe_blocksizes(bs->file->bs, bsz);
     }
 
     return -ENOTSUP;
@@ -513,6 +515,8 @@ int bdrv_probe_geometry(BlockDriverState *bs, HDGeometry *geo)
 
     if (drv && drv->bdrv_probe_geometry) {
         return drv->bdrv_probe_geometry(bs, geo);
+    } else if (drv && drv->is_filter && bs->file) {
+        return bdrv_probe_geometry(bs->file->bs, geo);
     }
 
     return -ENOTSUP;
@@ -3426,11 +3430,15 @@ int bdrv_truncate(BdrvChild *child, int64_t offset, PreallocMode prealloc,
 
     assert(child->perm & BLK_PERM_RESIZE);
 
+    /* if bs->drv == NULL, bs is closed, so there's nothing to do here */
     if (!drv) {
         error_setg(errp, "No medium inserted");
         return -ENOMEDIUM;
     }
     if (!drv->bdrv_truncate) {
+        if (bs->file && drv->is_filter) {
+            return bdrv_truncate(bs->file, offset, prealloc, errp);
+        }
         error_setg(errp, "Image format driver does not support resize");
         return -ENOTSUP;
     }
@@ -3767,6 +3775,9 @@ int bdrv_has_zero_init(BlockDriverState *bs)
     if (bs->drv->bdrv_has_zero_init) {
         return bs->drv->bdrv_has_zero_init(bs);
     }
+    if (bs->file && bs->drv->is_filter) {
+        return bdrv_has_zero_init(bs->file->bs);
+    }
 
     /* safe default */
     return 0;
@@ -3821,10 +3832,16 @@ void bdrv_get_backing_filename(BlockDriverState *bs,
 int bdrv_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
 {
     BlockDriver *drv = bs->drv;
-    if (!drv)
+    /* if bs->drv == NULL, bs is closed, so there's nothing to do here */
+    if (!drv) {
         return -ENOMEDIUM;
-    if (!drv->bdrv_get_info)
+    }
+    if (!drv->bdrv_get_info) {
+        if (bs->file && drv->is_filter) {
+            return bdrv_get_info(bs->file->bs, bdi);
+        }
         return -ENOTSUP;
+    }
     memset(bdi, 0, sizeof(*bdi));
     return drv->bdrv_get_info(bs, bdi);
 }
@@ -4175,20 +4192,6 @@ bool bdrv_is_inserted(BlockDriverState *bs)
 }
 
 /**
- * Return whether the media changed since the last call to this
- * function, or -ENOTSUP if we don't know.  Most drivers don't know.
- */
-int bdrv_media_changed(BlockDriverState *bs)
-{
-    BlockDriver *drv = bs->drv;
-
-    if (drv && drv->bdrv_media_changed) {
-        return drv->bdrv_media_changed(bs);
-    }
-    return -ENOTSUP;
-}
-
-/**
  * If eject_flag is TRUE, eject the media. Otherwise, close the tray
  */
 void bdrv_eject(BlockDriverState *bs, bool eject_flag)
diff --git a/block/Makefile.objs b/block/Makefile.objs
index 2aaede4ae1..6eaf78a046 100644
--- a/block/Makefile.objs
+++ b/block/Makefile.objs
@@ -25,6 +25,7 @@ block-obj-y += accounting.o dirty-bitmap.o
 block-obj-y += write-threshold.o
 block-obj-y += backup.o
 block-obj-$(CONFIG_REPLICATION) += replication.o
+block-obj-y += throttle.o
 
 block-obj-y += crypto.o
 
diff --git a/block/blkdebug.c b/block/blkdebug.c
index 8e385acf54..46e53f2f09 100644
--- a/block/blkdebug.c
+++ b/block/blkdebug.c
@@ -628,16 +628,6 @@ static int coroutine_fn blkdebug_co_pdiscard(BlockDriverState *bs,
     return bdrv_co_pdiscard(bs->file->bs, offset, bytes);
 }
 
-static int64_t coroutine_fn blkdebug_co_get_block_status(
-    BlockDriverState *bs, int64_t sector_num, int nb_sectors, int *pnum,
-    BlockDriverState **file)
-{
-    *pnum = nb_sectors;
-    *file = bs->file->bs;
-    return BDRV_BLOCK_RAW | BDRV_BLOCK_OFFSET_VALID |
-        (sector_num << BDRV_SECTOR_BITS);
-}
-
 static void blkdebug_close(BlockDriverState *bs)
 {
     BDRVBlkdebugState *s = bs->opaque;
@@ -808,12 +798,6 @@ static int64_t blkdebug_getlength(BlockDriverState *bs)
     return bdrv_getlength(bs->file->bs);
 }
 
-static int blkdebug_truncate(BlockDriverState *bs, int64_t offset,
-                             PreallocMode prealloc, Error **errp)
-{
-    return bdrv_truncate(bs->file, offset, prealloc, errp);
-}
-
 static void blkdebug_refresh_filename(BlockDriverState *bs, QDict *options)
 {
     BDRVBlkdebugState *s = bs->opaque;
@@ -896,6 +880,7 @@ static BlockDriver bdrv_blkdebug = {
     .format_name            = "blkdebug",
     .protocol_name          = "blkdebug",
     .instance_size          = sizeof(BDRVBlkdebugState),
+    .is_filter              = true,
 
     .bdrv_parse_filename    = blkdebug_parse_filename,
     .bdrv_file_open         = blkdebug_open,
@@ -904,7 +889,6 @@ static BlockDriver bdrv_blkdebug = {
     .bdrv_child_perm        = bdrv_filter_default_perms,
 
     .bdrv_getlength         = blkdebug_getlength,
-    .bdrv_truncate          = blkdebug_truncate,
     .bdrv_refresh_filename  = blkdebug_refresh_filename,
     .bdrv_refresh_limits    = blkdebug_refresh_limits,
 
@@ -913,7 +897,7 @@ static BlockDriver bdrv_blkdebug = {
     .bdrv_co_flush_to_disk  = blkdebug_co_flush,
     .bdrv_co_pwrite_zeroes  = blkdebug_co_pwrite_zeroes,
     .bdrv_co_pdiscard       = blkdebug_co_pdiscard,
-    .bdrv_co_get_block_status = blkdebug_co_get_block_status,
+    .bdrv_co_get_block_status = bdrv_co_get_block_status_from_file,
 
     .bdrv_debug_event           = blkdebug_debug_event,
     .bdrv_debug_breakpoint      = blkdebug_debug_breakpoint,
diff --git a/block/block-backend.c b/block/block-backend.c
index 1031742401..45d9101be3 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -273,9 +273,6 @@ BlockBackend *blk_new(uint64_t perm, uint64_t shared_perm)
     blk->shared_perm = shared_perm;
     blk_set_enable_write_cache(blk, true);
 
-    qemu_co_mutex_init(&blk->public.throttled_reqs_lock);
-    qemu_co_queue_init(&blk->public.throttled_reqs[0]);
-    qemu_co_queue_init(&blk->public.throttled_reqs[1]);
     block_acct_init(&blk->stats);
 
     notifier_list_init(&blk->remove_bs_notifiers);
@@ -343,7 +340,7 @@ static void blk_delete(BlockBackend *blk)
     assert(!blk->refcnt);
     assert(!blk->name);
     assert(!blk->dev);
-    if (blk->public.throttle_state) {
+    if (blk->public.throttle_group_member.throttle_state) {
         blk_io_limits_disable(blk);
     }
     if (blk->root) {
@@ -658,9 +655,12 @@ BlockBackend *blk_by_public(BlockBackendPublic *public)
  */
 void blk_remove_bs(BlockBackend *blk)
 {
+    ThrottleTimers *tt;
+
     notifier_list_notify(&blk->remove_bs_notifiers, blk);
-    if (blk->public.throttle_state) {
-        throttle_timers_detach_aio_context(&blk->public.throttle_timers);
+    if (blk->public.throttle_group_member.throttle_state) {
+        tt = &blk->public.throttle_group_member.throttle_timers;
+        throttle_timers_detach_aio_context(tt);
     }
 
     blk_update_root_state(blk);
@@ -682,9 +682,10 @@ int blk_insert_bs(BlockBackend *blk, BlockDriverState *bs, Error **errp)
     bdrv_ref(bs);
 
     notifier_list_notify(&blk->insert_bs_notifiers, blk);
-    if (blk->public.throttle_state) {
+    if (blk->public.throttle_group_member.throttle_state) {
         throttle_timers_attach_aio_context(
-            &blk->public.throttle_timers, bdrv_get_aio_context(bs));
+            &blk->public.throttle_group_member.throttle_timers,
+            bdrv_get_aio_context(bs));
     }
 
     return 0;
@@ -1046,8 +1047,9 @@ int coroutine_fn blk_co_preadv(BlockBackend *blk, int64_t offset,
     bdrv_inc_in_flight(bs);
 
     /* throttling disk I/O */
-    if (blk->public.throttle_state) {
-        throttle_group_co_io_limits_intercept(blk, bytes, false);
+    if (blk->public.throttle_group_member.throttle_state) {
+        throttle_group_co_io_limits_intercept(&blk->public.throttle_group_member,
+                bytes, false);
     }
 
     ret = bdrv_co_preadv(blk->root, offset, bytes, qiov, flags);
@@ -1070,10 +1072,10 @@ int coroutine_fn blk_co_pwritev(BlockBackend *blk, int64_t offset,
     }
 
     bdrv_inc_in_flight(bs);
-
     /* throttling disk I/O */
-    if (blk->public.throttle_state) {
-        throttle_group_co_io_limits_intercept(blk, bytes, true);
+    if (blk->public.throttle_group_member.throttle_state) {
+        throttle_group_co_io_limits_intercept(&blk->public.throttle_group_member,
+                bytes, true);
     }
 
     if (!blk->enable_write_cache) {
@@ -1742,16 +1744,14 @@ static AioContext *blk_aiocb_get_aio_context(BlockAIOCB *acb)
 void blk_set_aio_context(BlockBackend *blk, AioContext *new_context)
 {
     BlockDriverState *bs = blk_bs(blk);
+    ThrottleGroupMember *tgm = &blk->public.throttle_group_member;
 
     if (bs) {
-        if (blk->public.throttle_state) {
-            throttle_timers_detach_aio_context(&blk->public.throttle_timers);
+        if (tgm->throttle_state) {
+            throttle_group_detach_aio_context(tgm);
+            throttle_group_attach_aio_context(tgm, new_context);
         }
         bdrv_set_aio_context(bs, new_context);
-        if (blk->public.throttle_state) {
-            throttle_timers_attach_aio_context(&blk->public.throttle_timers,
-                                               new_context);
-        }
     }
 }
 
@@ -1969,33 +1969,35 @@ int blk_commit_all(void)
 /* throttling disk I/O limits */
 void blk_set_io_limits(BlockBackend *blk, ThrottleConfig *cfg)
 {
-    throttle_group_config(blk, cfg);
+    throttle_group_config(&blk->public.throttle_group_member, cfg);
 }
 
 void blk_io_limits_disable(BlockBackend *blk)
 {
-    assert(blk->public.throttle_state);
+    assert(blk->public.throttle_group_member.throttle_state);
     bdrv_drained_begin(blk_bs(blk));
-    throttle_group_unregister_blk(blk);
+    throttle_group_unregister_tgm(&blk->public.throttle_group_member);
     bdrv_drained_end(blk_bs(blk));
 }
 
 /* should be called before blk_set_io_limits if a limit is set */
 void blk_io_limits_enable(BlockBackend *blk, const char *group)
 {
-    assert(!blk->public.throttle_state);
-    throttle_group_register_blk(blk, group);
+    assert(!blk->public.throttle_group_member.throttle_state);
+    throttle_group_register_tgm(&blk->public.throttle_group_member,
+                                group, blk_get_aio_context(blk));
 }
 
 void blk_io_limits_update_group(BlockBackend *blk, const char *group)
 {
     /* this BB is not part of any group */
-    if (!blk->public.throttle_state) {
+    if (!blk->public.throttle_group_member.throttle_state) {
         return;
     }
 
     /* this BB is a part of the same group than the one we want */
-    if (!g_strcmp0(throttle_group_get_name(blk), group)) {
+    if (!g_strcmp0(throttle_group_get_name(&blk->public.throttle_group_member),
+                group)) {
         return;
     }
 
@@ -2017,8 +2019,8 @@ static void blk_root_drained_begin(BdrvChild *child)
     /* Note that blk->root may not be accessible here yet if we are just
      * attaching to a BlockDriverState that is drained. Use child instead. */
 
-    if (atomic_fetch_inc(&blk->public.io_limits_disabled) == 0) {
-        throttle_group_restart_blk(blk);
+    if (atomic_fetch_inc(&blk->public.throttle_group_member.io_limits_disabled) == 0) {
+        throttle_group_restart_tgm(&blk->public.throttle_group_member);
     }
 }
 
@@ -2027,8 +2029,8 @@ static void blk_root_drained_end(BdrvChild *child)
     BlockBackend *blk = child->opaque;
     assert(blk->quiesce_counter);
 
-    assert(blk->public.io_limits_disabled);
-    atomic_dec(&blk->public.io_limits_disabled);
+    assert(blk->public.throttle_group_member.io_limits_disabled);
+    atomic_dec(&blk->public.throttle_group_member.io_limits_disabled);
 
     if (--blk->quiesce_counter == 0) {
         if (blk->dev_ops && blk->dev_ops->drained_end) {
diff --git a/block/commit.c b/block/commit.c
index c7857c3321..898d91f653 100644
--- a/block/commit.c
+++ b/block/commit.c
@@ -244,16 +244,6 @@ static int coroutine_fn bdrv_commit_top_preadv(BlockDriverState *bs,
     return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags);
 }
 
-static int64_t coroutine_fn bdrv_commit_top_get_block_status(
-    BlockDriverState *bs, int64_t sector_num, int nb_sectors, int *pnum,
-    BlockDriverState **file)
-{
-    *pnum = nb_sectors;
-    *file = bs->backing->bs;
-    return BDRV_BLOCK_RAW | BDRV_BLOCK_OFFSET_VALID |
-           (sector_num << BDRV_SECTOR_BITS);
-}
-
 static void bdrv_commit_top_refresh_filename(BlockDriverState *bs, QDict *opts)
 {
     bdrv_refresh_filename(bs->backing->bs);
@@ -279,7 +269,7 @@ static void bdrv_commit_top_child_perm(BlockDriverState *bs, BdrvChild *c,
 static BlockDriver bdrv_commit_top = {
     .format_name                = "commit_top",
     .bdrv_co_preadv             = bdrv_commit_top_preadv,
-    .bdrv_co_get_block_status   = bdrv_commit_top_get_block_status,
+    .bdrv_co_get_block_status   = bdrv_co_get_block_status_from_backing,
     .bdrv_refresh_filename      = bdrv_commit_top_refresh_filename,
     .bdrv_close                 = bdrv_commit_top_close,
     .bdrv_child_perm            = bdrv_commit_top_child_perm,
diff --git a/block/io.c b/block/io.c
index 26003814eb..4378ae4c7d 100644
--- a/block/io.c
+++ b/block/io.c
@@ -1714,6 +1714,32 @@ typedef struct BdrvCoGetBlockStatusData {
     bool done;
 } BdrvCoGetBlockStatusData;
 
+int64_t coroutine_fn bdrv_co_get_block_status_from_file(BlockDriverState *bs,
+                                                        int64_t sector_num,
+                                                        int nb_sectors,
+                                                        int *pnum,
+                                                        BlockDriverState **file)
+{
+    assert(bs->file && bs->file->bs);
+    *pnum = nb_sectors;
+    *file = bs->file->bs;
+    return BDRV_BLOCK_RAW | BDRV_BLOCK_OFFSET_VALID |
+           (sector_num << BDRV_SECTOR_BITS);
+}
+
+int64_t coroutine_fn bdrv_co_get_block_status_from_backing(BlockDriverState *bs,
+                                                           int64_t sector_num,
+                                                           int nb_sectors,
+                                                           int *pnum,
+                                                           BlockDriverState **file)
+{
+    assert(bs->backing && bs->backing->bs);
+    *pnum = nb_sectors;
+    *file = bs->backing->bs;
+    return BDRV_BLOCK_RAW | BDRV_BLOCK_OFFSET_VALID |
+           (sector_num << BDRV_SECTOR_BITS);
+}
+
 /*
  * Returns the allocation status of the specified sectors.
  * Drivers not implementing the functionality are assumed to not support
diff --git a/block/mirror.c b/block/mirror.c
index 429751b9fe..6531652d73 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -1059,16 +1059,6 @@ static int coroutine_fn bdrv_mirror_top_flush(BlockDriverState *bs)
     return bdrv_co_flush(bs->backing->bs);
 }
 
-static int64_t coroutine_fn bdrv_mirror_top_get_block_status(
-    BlockDriverState *bs, int64_t sector_num, int nb_sectors, int *pnum,
-    BlockDriverState **file)
-{
-    *pnum = nb_sectors;
-    *file = bs->backing->bs;
-    return BDRV_BLOCK_RAW | BDRV_BLOCK_OFFSET_VALID |
-           (sector_num << BDRV_SECTOR_BITS);
-}
-
 static int coroutine_fn bdrv_mirror_top_pwrite_zeroes(BlockDriverState *bs,
     int64_t offset, int bytes, BdrvRequestFlags flags)
 {
@@ -1115,7 +1105,7 @@ static BlockDriver bdrv_mirror_top = {
     .bdrv_co_pwrite_zeroes      = bdrv_mirror_top_pwrite_zeroes,
     .bdrv_co_pdiscard           = bdrv_mirror_top_pdiscard,
     .bdrv_co_flush              = bdrv_mirror_top_flush,
-    .bdrv_co_get_block_status   = bdrv_mirror_top_get_block_status,
+    .bdrv_co_get_block_status   = bdrv_co_get_block_status_from_backing,
     .bdrv_refresh_filename      = bdrv_mirror_top_refresh_filename,
     .bdrv_close                 = bdrv_mirror_top_close,
     .bdrv_child_perm            = bdrv_mirror_top_child_perm,
diff --git a/block/qapi.c b/block/qapi.c
index 5f1a71f5d2..7fa2437923 100644
--- a/block/qapi.c
+++ b/block/qapi.c
@@ -66,10 +66,11 @@ BlockDeviceInfo *bdrv_block_device_info(BlockBackend *blk,
 
     info->detect_zeroes = bs->detect_zeroes;
 
-    if (blk && blk_get_public(blk)->throttle_state) {
+    if (blk && blk_get_public(blk)->throttle_group_member.throttle_state) {
         ThrottleConfig cfg;
+        BlockBackendPublic *blkp = blk_get_public(blk);
 
-        throttle_group_get_config(blk, &cfg);
+        throttle_group_get_config(&blkp->throttle_group_member, &cfg);
 
         info->bps     = cfg.buckets[THROTTLE_BPS_TOTAL].avg;
         info->bps_rd  = cfg.buckets[THROTTLE_BPS_READ].avg;
@@ -117,7 +118,8 @@ BlockDeviceInfo *bdrv_block_device_info(BlockBackend *blk,
         info->iops_size = cfg.op_size;
 
         info->has_group = true;
-        info->group = g_strdup(throttle_group_get_name(blk));
+        info->group =
+            g_strdup(throttle_group_get_name(&blkp->throttle_group_member));
     }
 
     info->write_threshold = bdrv_write_threshold_get(bs);
diff --git a/block/qcow.c b/block/qcow.c
index 63904a26ee..f450b00cfc 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -347,19 +347,22 @@ static int qcow_reopen_prepare(BDRVReopenState *state,
  * 'compressed_size'. 'compressed_size' must be > 0 and <
  * cluster_size
  *
- * return 0 if not allocated.
+ * return 0 if not allocated, 1 if *result is assigned, and negative
+ * errno on failure.
  */
-static uint64_t get_cluster_offset(BlockDriverState *bs,
-                                   uint64_t offset, int allocate,
-                                   int compressed_size,
-                                   int n_start, int n_end)
+static int get_cluster_offset(BlockDriverState *bs,
+                              uint64_t offset, int allocate,
+                              int compressed_size,
+                              int n_start, int n_end, uint64_t *result)
 {
     BDRVQcowState *s = bs->opaque;
-    int min_index, i, j, l1_index, l2_index;
-    uint64_t l2_offset, *l2_table, cluster_offset, tmp;
+    int min_index, i, j, l1_index, l2_index, ret;
+    int64_t l2_offset;
+    uint64_t *l2_table, cluster_offset, tmp;
     uint32_t min_count;
     int new_l2_table;
 
+    *result = 0;
     l1_index = offset >> (s->l2_bits + s->cluster_bits);
     l2_offset = s->l1_table[l1_index];
     new_l2_table = 0;
@@ -368,15 +371,20 @@ static uint64_t get_cluster_offset(BlockDriverState *bs,
             return 0;
         /* allocate a new l2 entry */
         l2_offset = bdrv_getlength(bs->file->bs);
+        if (l2_offset < 0) {
+            return l2_offset;
+        }
         /* round to cluster size */
-        l2_offset = (l2_offset + s->cluster_size - 1) & ~(s->cluster_size - 1);
+        l2_offset = QEMU_ALIGN_UP(l2_offset, s->cluster_size);
         /* update the L1 entry */
         s->l1_table[l1_index] = l2_offset;
         tmp = cpu_to_be64(l2_offset);
-        if (bdrv_pwrite_sync(bs->file,
-                s->l1_table_offset + l1_index * sizeof(tmp),
-                &tmp, sizeof(tmp)) < 0)
-            return 0;
+        ret = bdrv_pwrite_sync(bs->file,
+                               s->l1_table_offset + l1_index * sizeof(tmp),
+                               &tmp, sizeof(tmp));
+        if (ret < 0) {
+            return ret;
+        }
         new_l2_table = 1;
     }
     for(i = 0; i < L2_CACHE_SIZE; i++) {
@@ -403,14 +411,17 @@ static uint64_t get_cluster_offset(BlockDriverState *bs,
     l2_table = s->l2_cache + (min_index << s->l2_bits);
     if (new_l2_table) {
         memset(l2_table, 0, s->l2_size * sizeof(uint64_t));
-        if (bdrv_pwrite_sync(bs->file, l2_offset, l2_table,
-                s->l2_size * sizeof(uint64_t)) < 0)
-            return 0;
+        ret = bdrv_pwrite_sync(bs->file, l2_offset, l2_table,
+                               s->l2_size * sizeof(uint64_t));
+        if (ret < 0) {
+            return ret;
+        }
     } else {
-        if (bdrv_pread(bs->file, l2_offset, l2_table,
-                       s->l2_size * sizeof(uint64_t)) !=
-            s->l2_size * sizeof(uint64_t))
-            return 0;
+        ret = bdrv_pread(bs->file, l2_offset, l2_table,
+                         s->l2_size * sizeof(uint64_t));
+        if (ret < 0) {
+            return ret;
+        }
     }
     s->l2_cache_offsets[min_index] = l2_offset;
     s->l2_cache_counts[min_index] = 1;
@@ -427,24 +438,36 @@ static uint64_t get_cluster_offset(BlockDriverState *bs,
             /* if the cluster is already compressed, we must
                decompress it in the case it is not completely
                overwritten */
-            if (decompress_cluster(bs, cluster_offset) < 0)
-                return 0;
+            if (decompress_cluster(bs, cluster_offset) < 0) {
+                return -EIO;
+            }
             cluster_offset = bdrv_getlength(bs->file->bs);
-            cluster_offset = (cluster_offset + s->cluster_size - 1) &
-                ~(s->cluster_size - 1);
+            if ((int64_t) cluster_offset < 0) {
+                return cluster_offset;
+            }
+            cluster_offset = QEMU_ALIGN_UP(cluster_offset, s->cluster_size);
             /* write the cluster content */
-            if (bdrv_pwrite(bs->file, cluster_offset, s->cluster_cache,
-                            s->cluster_size) !=
-                s->cluster_size)
-                return -1;
+            ret = bdrv_pwrite(bs->file, cluster_offset, s->cluster_cache,
+                              s->cluster_size);
+            if (ret < 0) {
+                return ret;
+            }
         } else {
             cluster_offset = bdrv_getlength(bs->file->bs);
+            if ((int64_t) cluster_offset < 0) {
+                return cluster_offset;
+            }
             if (allocate == 1) {
                 /* round to cluster size */
-                cluster_offset = (cluster_offset + s->cluster_size - 1) &
-                    ~(s->cluster_size - 1);
-                bdrv_truncate(bs->file, cluster_offset + s->cluster_size,
-                              PREALLOC_MODE_OFF, NULL);
+                cluster_offset = QEMU_ALIGN_UP(cluster_offset, s->cluster_size);
+                if (cluster_offset + s->cluster_size > INT64_MAX) {
+                    return -E2BIG;
+                }
+                ret = bdrv_truncate(bs->file, cluster_offset + s->cluster_size,
+                                    PREALLOC_MODE_OFF, NULL);
+                if (ret < 0) {
+                    return ret;
+                }
                 /* if encrypted, we must initialize the cluster
                    content which won't be written */
                 if (bs->encrypted &&
@@ -459,13 +482,14 @@ static uint64_t get_cluster_offset(BlockDriverState *bs,
                                                       s->cluster_data,
                                                       BDRV_SECTOR_SIZE,
                                                       NULL) < 0) {
-                                errno = EIO;
-                                return -1;
+                                return -EIO;
+                            }
+                            ret = bdrv_pwrite(bs->file,
+                                              cluster_offset + i * 512,
+                                              s->cluster_data, 512);
+                            if (ret < 0) {
+                                return ret;
                             }
-                            if (bdrv_pwrite(bs->file,
-                                            cluster_offset + i * 512,
-                                            s->cluster_data, 512) != 512)
-                                return -1;
                         }
                     }
                 }
@@ -477,23 +501,29 @@ static uint64_t get_cluster_offset(BlockDriverState *bs,
         /* update L2 table */
         tmp = cpu_to_be64(cluster_offset);
         l2_table[l2_index] = tmp;
-        if (bdrv_pwrite_sync(bs->file, l2_offset + l2_index * sizeof(tmp),
-                &tmp, sizeof(tmp)) < 0)
-            return 0;
+        ret = bdrv_pwrite_sync(bs->file, l2_offset + l2_index * sizeof(tmp),
+                               &tmp, sizeof(tmp));
+        if (ret < 0) {
+            return ret;
+        }
     }
-    return cluster_offset;
+    *result = cluster_offset;
+    return 1;
 }
 
 static int64_t coroutine_fn qcow_co_get_block_status(BlockDriverState *bs,
         int64_t sector_num, int nb_sectors, int *pnum, BlockDriverState **file)
 {
     BDRVQcowState *s = bs->opaque;
-    int index_in_cluster, n;
+    int index_in_cluster, n, ret;
     uint64_t cluster_offset;
 
     qemu_co_mutex_lock(&s->lock);
-    cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0);
+    ret = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0, &cluster_offset);
     qemu_co_mutex_unlock(&s->lock);
+    if (ret < 0) {
+        return ret;
+    }
     index_in_cluster = sector_num & (s->cluster_sectors - 1);
     n = s->cluster_sectors - index_in_cluster;
     if (n > nb_sectors)
@@ -585,8 +615,11 @@ static coroutine_fn int qcow_co_readv(BlockDriverState *bs, int64_t sector_num,
 
     while (nb_sectors != 0) {
         /* prepare next request */
-        cluster_offset = get_cluster_offset(bs, sector_num << 9,
-                                                 0, 0, 0, 0);
+        ret = get_cluster_offset(bs, sector_num << 9,
+                                 0, 0, 0, 0, &cluster_offset);
+        if (ret < 0) {
+            break;
+        }
         index_in_cluster = sector_num & (s->cluster_sectors - 1);
         n = s->cluster_sectors - index_in_cluster;
         if (n > nb_sectors) {
@@ -603,7 +636,7 @@ static coroutine_fn int qcow_co_readv(BlockDriverState *bs, int64_t sector_num,
                 ret = bdrv_co_readv(bs->backing, sector_num, n, &hd_qiov);
                 qemu_co_mutex_lock(&s->lock);
                 if (ret < 0) {
-                    goto fail;
+                    break;
                 }
             } else {
                 /* Note: in this case, no need to wait */
@@ -612,13 +645,15 @@ static coroutine_fn int qcow_co_readv(BlockDriverState *bs, int64_t sector_num,
         } else if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
             /* add AIO support for compressed blocks ? */
             if (decompress_cluster(bs, cluster_offset) < 0) {
-                goto fail;
+                ret = -EIO;
+                break;
             }
             memcpy(buf,
                    s->cluster_cache + index_in_cluster * 512, 512 * n);
         } else {
             if ((cluster_offset & 511) != 0) {
-                goto fail;
+                ret = -EIO;
+                break;
             }
             hd_iov.iov_base = (void *)buf;
             hd_iov.iov_len = n * 512;
@@ -635,7 +670,8 @@ static coroutine_fn int qcow_co_readv(BlockDriverState *bs, int64_t sector_num,
                 assert(s->crypto);
                 if (qcrypto_block_decrypt(s->crypto, sector_num, buf,
                                           n * BDRV_SECTOR_SIZE, NULL) < 0) {
-                    goto fail;
+                    ret = -EIO;
+                    break;
                 }
             }
         }
@@ -646,7 +682,6 @@ static coroutine_fn int qcow_co_readv(BlockDriverState *bs, int64_t sector_num,
         buf += n * 512;
     }
 
-done:
     qemu_co_mutex_unlock(&s->lock);
 
     if (qiov->niov > 1) {
@@ -655,10 +690,6 @@ done:
     }
 
     return ret;
-
-fail:
-    ret = -EIO;
-    goto done;
 }
 
 static coroutine_fn int qcow_co_writev(BlockDriverState *bs, int64_t sector_num,
@@ -697,9 +728,12 @@ static coroutine_fn int qcow_co_writev(BlockDriverState *bs, int64_t sector_num,
         if (n > nb_sectors) {
             n = nb_sectors;
         }
-        cluster_offset = get_cluster_offset(bs, sector_num << 9, 1, 0,
-                                            index_in_cluster,
-                                            index_in_cluster + n);
+        ret = get_cluster_offset(bs, sector_num << 9, 1, 0,
+                                 index_in_cluster,
+                                 index_in_cluster + n, &cluster_offset);
+        if (ret < 0) {
+            break;
+        }
         if (!cluster_offset || (cluster_offset & 511) != 0) {
             ret = -EIO;
             break;
@@ -995,8 +1029,11 @@ qcow_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
         goto success;
     }
     qemu_co_mutex_lock(&s->lock);
-    cluster_offset = get_cluster_offset(bs, offset, 2, out_len, 0, 0);
+    ret = get_cluster_offset(bs, offset, 2, out_len, 0, 0, &cluster_offset);
     qemu_co_mutex_unlock(&s->lock);
+    if (ret < 0) {
+        goto fail;
+    }
     if (cluster_offset == 0) {
         ret = -EIO;
         goto fail;
diff --git a/block/qcow2.c b/block/qcow2.c
index 2ec399663e..bae5893327 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -2036,6 +2036,14 @@ static int qcow2_inactivate(BlockDriverState *bs)
     int ret, result = 0;
     Error *local_err = NULL;
 
+    qcow2_store_persistent_dirty_bitmaps(bs, &local_err);
+    if (local_err != NULL) {
+        result = -EINVAL;
+        error_report_err(local_err);
+        error_report("Persistent bitmaps are lost for node '%s'",
+                     bdrv_get_device_or_node_name(bs));
+    }
+
     ret = qcow2_cache_flush(bs, s->l2_table_cache);
     if (ret) {
         result = ret;
@@ -2050,14 +2058,6 @@ static int qcow2_inactivate(BlockDriverState *bs)
                      strerror(-ret));
     }
 
-    qcow2_store_persistent_dirty_bitmaps(bs, &local_err);
-    if (local_err != NULL) {
-        result = -EINVAL;
-        error_report_err(local_err);
-        error_report("Persistent bitmaps are lost for node '%s'",
-                     bdrv_get_device_or_node_name(bs));
-    }
-
     if (result == 0) {
         qcow2_mark_clean(bs);
     }
diff --git a/block/raw-format.c b/block/raw-format.c
index 142649ed56..ab552c0954 100644
--- a/block/raw-format.c
+++ b/block/raw-format.c
@@ -372,11 +372,6 @@ static int raw_truncate(BlockDriverState *bs, int64_t offset,
     return bdrv_truncate(bs->file, offset, prealloc, errp);
 }
 
-static int raw_media_changed(BlockDriverState *bs)
-{
-    return bdrv_media_changed(bs->file->bs);
-}
-
 static void raw_eject(BlockDriverState *bs, bool eject_flag)
 {
     bdrv_eject(bs->file->bs, eject_flag);
@@ -510,7 +505,6 @@ BlockDriver bdrv_raw = {
     .bdrv_refresh_limits  = &raw_refresh_limits,
     .bdrv_probe_blocksizes = &raw_probe_blocksizes,
     .bdrv_probe_geometry  = &raw_probe_geometry,
-    .bdrv_media_changed   = &raw_media_changed,
     .bdrv_eject           = &raw_eject,
     .bdrv_lock_medium     = &raw_lock_medium,
     .bdrv_co_ioctl        = &raw_co_ioctl,
diff --git a/block/throttle-groups.c b/block/throttle-groups.c
index 890bfded3f..6ba992c8d7 100644
--- a/block/throttle-groups.c
+++ b/block/throttle-groups.c
@@ -25,12 +25,20 @@
 #include "qemu/osdep.h"
 #include "sysemu/block-backend.h"
 #include "block/throttle-groups.h"
+#include "qemu/throttle-options.h"
 #include "qemu/queue.h"
 #include "qemu/thread.h"
 #include "sysemu/qtest.h"
+#include "qapi/error.h"
+#include "qapi-visit.h"
+#include "qom/object.h"
+#include "qom/object_interfaces.h"
+
+static void throttle_group_obj_init(Object *obj);
+static void throttle_group_obj_complete(UserCreatable *obj, Error **errp);
 
 /* The ThrottleGroup structure (with its ThrottleState) is shared
- * among different BlockBackends and it's independent from
+ * among different ThrottleGroupMembers and it's independent from
  * AioContext, so in order to use it from different threads it needs
  * its own locking.
  *
@@ -40,82 +48,95 @@
  * The whole ThrottleGroup structure is private and invisible to
  * outside users, that only use it through its ThrottleState.
  *
- * In addition to the ThrottleGroup structure, BlockBackendPublic has
+ * In addition to the ThrottleGroup structure, ThrottleGroupMember has
  * fields that need to be accessed by other members of the group and
  * therefore also need to be protected by this lock. Once a
- * BlockBackend is registered in a group those fields can be accessed
+ * ThrottleGroupMember is registered in a group those fields can be accessed
  * by other threads any time.
  *
  * Again, all this is handled internally and is mostly transparent to
  * the outside. The 'throttle_timers' field however has an additional
  * constraint because it may be temporarily invalid (see for example
  * blk_set_aio_context()). Therefore in this file a thread will
- * access some other BlockBackend's timers only after verifying that
- * that BlockBackend has throttled requests in the queue.
+ * access some other ThrottleGroupMember's timers only after verifying that
+ * that ThrottleGroupMember has throttled requests in the queue.
  */
 typedef struct ThrottleGroup {
+    Object parent_obj;
+
+    /* refuse individual property change if initialization is complete */
+    bool is_initialized;
     char *name; /* This is constant during the lifetime of the group */
 
     QemuMutex lock; /* This lock protects the following four fields */
     ThrottleState ts;
-    QLIST_HEAD(, BlockBackendPublic) head;
-    BlockBackend *tokens[2];
+    QLIST_HEAD(, ThrottleGroupMember) head;
+    ThrottleGroupMember *tokens[2];
     bool any_timer_armed[2];
     QEMUClockType clock_type;
 
-    /* These two are protected by the global throttle_groups_lock */
-    unsigned refcount;
+    /* This field is protected by the global QEMU mutex */
     QTAILQ_ENTRY(ThrottleGroup) list;
 } ThrottleGroup;
 
-static QemuMutex throttle_groups_lock;
+/* This is protected by the global QEMU mutex */
 static QTAILQ_HEAD(, ThrottleGroup) throttle_groups =
     QTAILQ_HEAD_INITIALIZER(throttle_groups);
 
+
+/* This function reads throttle_groups and must be called under the global
+ * mutex.
+ */
+static ThrottleGroup *throttle_group_by_name(const char *name)
+{
+    ThrottleGroup *iter;
+
+    /* Look for an existing group with that name */
+    QTAILQ_FOREACH(iter, &throttle_groups, list) {
+        if (!g_strcmp0(name, iter->name)) {
+            return iter;
+        }
+    }
+
+    return NULL;
+}
+
+/* This function reads throttle_groups and must be called under the global
+ * mutex.
+ */
+bool throttle_group_exists(const char *name)
+{
+    return throttle_group_by_name(name) != NULL;
+}
+
 /* Increments the reference count of a ThrottleGroup given its name.
  *
  * If no ThrottleGroup is found with the given name a new one is
  * created.
  *
+ * This function edits throttle_groups and must be called under the global
+ * mutex.
+ *
  * @name: the name of the ThrottleGroup
  * @ret:  the ThrottleState member of the ThrottleGroup
  */
 ThrottleState *throttle_group_incref(const char *name)
 {
     ThrottleGroup *tg = NULL;
-    ThrottleGroup *iter;
-
-    qemu_mutex_lock(&throttle_groups_lock);
 
     /* Look for an existing group with that name */
-    QTAILQ_FOREACH(iter, &throttle_groups, list) {
-        if (!strcmp(name, iter->name)) {
-            tg = iter;
-            break;
-        }
-    }
-
-    /* Create a new one if not found */
-    if (!tg) {
-        tg = g_new0(ThrottleGroup, 1);
+    tg = throttle_group_by_name(name);
+
+    if (tg) {
+        object_ref(OBJECT(tg));
+    } else {
+        /* Create a new one if not found */
+        /* new ThrottleGroup obj will have a refcnt = 1 */
+        tg = THROTTLE_GROUP(object_new(TYPE_THROTTLE_GROUP));
         tg->name = g_strdup(name);
-        tg->clock_type = QEMU_CLOCK_REALTIME;
-
-        if (qtest_enabled()) {
-            /* For testing block IO throttling only */
-            tg->clock_type = QEMU_CLOCK_VIRTUAL;
-        }
-        qemu_mutex_init(&tg->lock);
-        throttle_init(&tg->ts);
-        QLIST_INIT(&tg->head);
-
-        QTAILQ_INSERT_TAIL(&throttle_groups, tg, list);
+        throttle_group_obj_complete(USER_CREATABLE(tg), &error_abort);
     }
 
-    tg->refcount++;
-
-    qemu_mutex_unlock(&throttle_groups_lock);
-
     return &tg->ts;
 }
 
@@ -124,130 +145,123 @@ ThrottleState *throttle_group_incref(const char *name)
  * When the reference count reaches zero the ThrottleGroup is
  * destroyed.
  *
+ * This function edits throttle_groups and must be called under the global
+ * mutex.
+ *
  * @ts:  The ThrottleGroup to unref, given by its ThrottleState member
  */
 void throttle_group_unref(ThrottleState *ts)
 {
     ThrottleGroup *tg = container_of(ts, ThrottleGroup, ts);
-
-    qemu_mutex_lock(&throttle_groups_lock);
-    if (--tg->refcount == 0) {
-        QTAILQ_REMOVE(&throttle_groups, tg, list);
-        qemu_mutex_destroy(&tg->lock);
-        g_free(tg->name);
-        g_free(tg);
-    }
-    qemu_mutex_unlock(&throttle_groups_lock);
+    object_unref(OBJECT(tg));
 }
 
-/* Get the name from a BlockBackend's ThrottleGroup. The name (and the pointer)
+/* Get the name from a ThrottleGroupMember's group. The name (and the pointer)
  * is guaranteed to remain constant during the lifetime of the group.
  *
- * @blk:  a BlockBackend that is member of a throttling group
+ * @tgm:  a ThrottleGroupMember
  * @ret:  the name of the group.
  */
-const char *throttle_group_get_name(BlockBackend *blk)
+const char *throttle_group_get_name(ThrottleGroupMember *tgm)
 {
-    BlockBackendPublic *blkp = blk_get_public(blk);
-    ThrottleGroup *tg = container_of(blkp->throttle_state, ThrottleGroup, ts);
+    ThrottleGroup *tg = container_of(tgm->throttle_state, ThrottleGroup, ts);
     return tg->name;
 }
 
-/* Return the next BlockBackend in the round-robin sequence, simulating a
- * circular list.
+/* Return the next ThrottleGroupMember in the round-robin sequence, simulating
+ * a circular list.
  *
  * This assumes that tg->lock is held.
  *
- * @blk: the current BlockBackend
- * @ret: the next BlockBackend in the sequence
+ * @tgm: the current ThrottleGroupMember
+ * @ret: the next ThrottleGroupMember in the sequence
  */
-static BlockBackend *throttle_group_next_blk(BlockBackend *blk)
+static ThrottleGroupMember *throttle_group_next_tgm(ThrottleGroupMember *tgm)
 {
-    BlockBackendPublic *blkp = blk_get_public(blk);
-    ThrottleState *ts = blkp->throttle_state;
+    ThrottleState *ts = tgm->throttle_state;
     ThrottleGroup *tg = container_of(ts, ThrottleGroup, ts);
-    BlockBackendPublic *next = QLIST_NEXT(blkp, round_robin);
+    ThrottleGroupMember *next = QLIST_NEXT(tgm, round_robin);
 
     if (!next) {
         next = QLIST_FIRST(&tg->head);
     }
 
-    return blk_by_public(next);
+    return next;
 }
 
 /*
- * Return whether a BlockBackend has pending requests.
+ * Return whether a ThrottleGroupMember has pending requests.
  *
  * This assumes that tg->lock is held.
  *
- * @blk: the BlockBackend
- * @is_write:  the type of operation (read/write)
- * @ret:       whether the BlockBackend has pending requests.
+ * @tgm:        the ThrottleGroupMember
+ * @is_write:   the type of operation (read/write)
+ * @ret:        whether the ThrottleGroupMember has pending requests.
  */
-static inline bool blk_has_pending_reqs(BlockBackend *blk,
+static inline bool tgm_has_pending_reqs(ThrottleGroupMember *tgm,
                                         bool is_write)
 {
-    const BlockBackendPublic *blkp = blk_get_public(blk);
-    return blkp->pending_reqs[is_write];
+    return tgm->pending_reqs[is_write];
 }
 
-/* Return the next BlockBackend in the round-robin sequence with pending I/O
- * requests.
+/* Return the next ThrottleGroupMember in the round-robin sequence with pending
+ * I/O requests.
  *
  * This assumes that tg->lock is held.
  *
- * @blk:       the current BlockBackend
+ * @tgm:       the current ThrottleGroupMember
  * @is_write:  the type of operation (read/write)
- * @ret:       the next BlockBackend with pending requests, or blk if there is
- *             none.
+ * @ret:       the next ThrottleGroupMember with pending requests, or tgm if
+ *             there is none.
  */
-static BlockBackend *next_throttle_token(BlockBackend *blk, bool is_write)
+static ThrottleGroupMember *next_throttle_token(ThrottleGroupMember *tgm,
+                                                bool is_write)
 {
-    BlockBackendPublic *blkp = blk_get_public(blk);
-    ThrottleGroup *tg = container_of(blkp->throttle_state, ThrottleGroup, ts);
-    BlockBackend *token, *start;
+    ThrottleState *ts = tgm->throttle_state;
+    ThrottleGroup *tg = container_of(ts, ThrottleGroup, ts);
+    ThrottleGroupMember *token, *start;
 
     start = token = tg->tokens[is_write];
 
     /* get next bs round in round robin style */
-    token = throttle_group_next_blk(token);
-    while (token != start && !blk_has_pending_reqs(token, is_write)) {
-        token = throttle_group_next_blk(token);
+    token = throttle_group_next_tgm(token);
+    while (token != start && !tgm_has_pending_reqs(token, is_write)) {
+        token = throttle_group_next_tgm(token);
     }
 
     /* If no IO are queued for scheduling on the next round robin token
-     * then decide the token is the current bs because chances are
-     * the current bs get the current request queued.
+     * then decide the token is the current tgm because chances are
+     * the current tgm got the current request queued.
      */
-    if (token == start && !blk_has_pending_reqs(token, is_write)) {
-        token = blk;
+    if (token == start && !tgm_has_pending_reqs(token, is_write)) {
+        token = tgm;
     }
 
-    /* Either we return the original BB, or one with pending requests */
-    assert(token == blk || blk_has_pending_reqs(token, is_write));
+    /* Either we return the original TGM, or one with pending requests */
+    assert(token == tgm || tgm_has_pending_reqs(token, is_write));
 
     return token;
 }
 
-/* Check if the next I/O request for a BlockBackend needs to be throttled or
- * not. If there's no timer set in this group, set one and update the token
- * accordingly.
+/* Check if the next I/O request for a ThrottleGroupMember needs to be
+ * throttled or not. If there's no timer set in this group, set one and update
+ * the token accordingly.
  *
  * This assumes that tg->lock is held.
  *
- * @blk:        the current BlockBackend
+ * @tgm:        the current ThrottleGroupMember
  * @is_write:   the type of operation (read/write)
  * @ret:        whether the I/O request needs to be throttled or not
  */
-static bool throttle_group_schedule_timer(BlockBackend *blk, bool is_write)
+static bool throttle_group_schedule_timer(ThrottleGroupMember *tgm,
+                                          bool is_write)
 {
-    BlockBackendPublic *blkp = blk_get_public(blk);
-    ThrottleState *ts = blkp->throttle_state;
-    ThrottleTimers *tt = &blkp->throttle_timers;
+    ThrottleState *ts = tgm->throttle_state;
     ThrottleGroup *tg = container_of(ts, ThrottleGroup, ts);
+    ThrottleTimers *tt = &tgm->throttle_timers;
     bool must_wait;
 
-    if (atomic_read(&blkp->io_limits_disabled)) {
+    if (atomic_read(&tgm->io_limits_disabled)) {
         return false;
     }
 
@@ -258,30 +272,29 @@ static bool throttle_group_schedule_timer(BlockBackend *blk, bool is_write)
 
     must_wait = throttle_schedule_timer(ts, tt, is_write);
 
-    /* If a timer just got armed, set blk as the current token */
+    /* If a timer just got armed, set tgm as the current token */
     if (must_wait) {
-        tg->tokens[is_write] = blk;
+        tg->tokens[is_write] = tgm;
         tg->any_timer_armed[is_write] = true;
     }
 
     return must_wait;
 }
 
-/* Start the next pending I/O request for a BlockBackend.  Return whether
+/* Start the next pending I/O request for a ThrottleGroupMember. Return whether
  * any request was actually pending.
  *
- * @blk:       the current BlockBackend
+ * @tgm:       the current ThrottleGroupMember
  * @is_write:  the type of operation (read/write)
  */
-static bool coroutine_fn throttle_group_co_restart_queue(BlockBackend *blk,
+static bool coroutine_fn throttle_group_co_restart_queue(ThrottleGroupMember *tgm,
                                                          bool is_write)
 {
-    BlockBackendPublic *blkp = blk_get_public(blk);
     bool ret;
 
-    qemu_co_mutex_lock(&blkp->throttled_reqs_lock);
-    ret = qemu_co_queue_next(&blkp->throttled_reqs[is_write]);
-    qemu_co_mutex_unlock(&blkp->throttled_reqs_lock);
+    qemu_co_mutex_lock(&tgm->throttled_reqs_lock);
+    ret = qemu_co_queue_next(&tgm->throttled_reqs[is_write]);
+    qemu_co_mutex_unlock(&tgm->throttled_reqs_lock);
 
     return ret;
 }
@@ -290,19 +303,19 @@ static bool coroutine_fn throttle_group_co_restart_queue(BlockBackend *blk,
  *
  * This assumes that tg->lock is held.
  *
- * @blk:       the current BlockBackend
+ * @tgm:       the current ThrottleGroupMember
  * @is_write:  the type of operation (read/write)
  */
-static void schedule_next_request(BlockBackend *blk, bool is_write)
+static void schedule_next_request(ThrottleGroupMember *tgm, bool is_write)
 {
-    BlockBackendPublic *blkp = blk_get_public(blk);
-    ThrottleGroup *tg = container_of(blkp->throttle_state, ThrottleGroup, ts);
+    ThrottleState *ts = tgm->throttle_state;
+    ThrottleGroup *tg = container_of(ts, ThrottleGroup, ts);
     bool must_wait;
-    BlockBackend *token;
+    ThrottleGroupMember *token;
 
     /* Check if there's any pending request to schedule next */
-    token = next_throttle_token(blk, is_write);
-    if (!blk_has_pending_reqs(token, is_write)) {
+    token = next_throttle_token(tgm, is_write);
+    if (!tgm_has_pending_reqs(token, is_write)) {
         return;
     }
 
@@ -311,12 +324,12 @@ static void schedule_next_request(BlockBackend *blk, bool is_write)
 
     /* If it doesn't have to wait, queue it for immediate execution */
     if (!must_wait) {
-        /* Give preference to requests from the current blk */
+        /* Give preference to requests from the current tgm */
         if (qemu_in_coroutine() &&
-            throttle_group_co_restart_queue(blk, is_write)) {
-            token = blk;
+            throttle_group_co_restart_queue(tgm, is_write)) {
+            token = tgm;
         } else {
-            ThrottleTimers *tt = &blk_get_public(token)->throttle_timers;
+            ThrottleTimers *tt = &token->throttle_timers;
             int64_t now = qemu_clock_get_ns(tg->clock_type);
             timer_mod(tt->timers[is_write], now);
             tg->any_timer_armed[is_write] = true;
@@ -329,90 +342,86 @@ static void schedule_next_request(BlockBackend *blk, bool is_write)
  * if necessary, and schedule the next request using a round robin
  * algorithm.
  *
- * @blk:       the current BlockBackend
+ * @tgm:       the current ThrottleGroupMember
  * @bytes:     the number of bytes for this I/O
  * @is_write:  the type of operation (read/write)
  */
-void coroutine_fn throttle_group_co_io_limits_intercept(BlockBackend *blk,
+void coroutine_fn throttle_group_co_io_limits_intercept(ThrottleGroupMember *tgm,
                                                         unsigned int bytes,
                                                         bool is_write)
 {
     bool must_wait;
-    BlockBackend *token;
-
-    BlockBackendPublic *blkp = blk_get_public(blk);
-    ThrottleGroup *tg = container_of(blkp->throttle_state, ThrottleGroup, ts);
+    ThrottleGroupMember *token;
+    ThrottleGroup *tg = container_of(tgm->throttle_state, ThrottleGroup, ts);
     qemu_mutex_lock(&tg->lock);
 
     /* First we check if this I/O has to be throttled. */
-    token = next_throttle_token(blk, is_write);
+    token = next_throttle_token(tgm, is_write);
     must_wait = throttle_group_schedule_timer(token, is_write);
 
     /* Wait if there's a timer set or queued requests of this type */
-    if (must_wait || blkp->pending_reqs[is_write]) {
-        blkp->pending_reqs[is_write]++;
+    if (must_wait || tgm->pending_reqs[is_write]) {
+        tgm->pending_reqs[is_write]++;
         qemu_mutex_unlock(&tg->lock);
-        qemu_co_mutex_lock(&blkp->throttled_reqs_lock);
-        qemu_co_queue_wait(&blkp->throttled_reqs[is_write],
-                           &blkp->throttled_reqs_lock);
-        qemu_co_mutex_unlock(&blkp->throttled_reqs_lock);
+        qemu_co_mutex_lock(&tgm->throttled_reqs_lock);
+        qemu_co_queue_wait(&tgm->throttled_reqs[is_write],
+                           &tgm->throttled_reqs_lock);
+        qemu_co_mutex_unlock(&tgm->throttled_reqs_lock);
         qemu_mutex_lock(&tg->lock);
-        blkp->pending_reqs[is_write]--;
+        tgm->pending_reqs[is_write]--;
     }
 
     /* The I/O will be executed, so do the accounting */
-    throttle_account(blkp->throttle_state, is_write, bytes);
+    throttle_account(tgm->throttle_state, is_write, bytes);
 
     /* Schedule the next request */
-    schedule_next_request(blk, is_write);
+    schedule_next_request(tgm, is_write);
 
     qemu_mutex_unlock(&tg->lock);
 }
 
 typedef struct {
-    BlockBackend *blk;
+    ThrottleGroupMember *tgm;
     bool is_write;
 } RestartData;
 
 static void coroutine_fn throttle_group_restart_queue_entry(void *opaque)
 {
     RestartData *data = opaque;
-    BlockBackend *blk = data->blk;
+    ThrottleGroupMember *tgm = data->tgm;
+    ThrottleState *ts = tgm->throttle_state;
+    ThrottleGroup *tg = container_of(ts, ThrottleGroup, ts);
     bool is_write = data->is_write;
-    BlockBackendPublic *blkp = blk_get_public(blk);
-    ThrottleGroup *tg = container_of(blkp->throttle_state, ThrottleGroup, ts);
     bool empty_queue;
 
-    empty_queue = !throttle_group_co_restart_queue(blk, is_write);
+    empty_queue = !throttle_group_co_restart_queue(tgm, is_write);
 
     /* If the request queue was empty then we have to take care of
      * scheduling the next one */
     if (empty_queue) {
         qemu_mutex_lock(&tg->lock);
-        schedule_next_request(blk, is_write);
+        schedule_next_request(tgm, is_write);
         qemu_mutex_unlock(&tg->lock);
     }
 }
 
-static void throttle_group_restart_queue(BlockBackend *blk, bool is_write)
+static void throttle_group_restart_queue(ThrottleGroupMember *tgm, bool is_write)
 {
     Coroutine *co;
     RestartData rd = {
-        .blk = blk,
+        .tgm = tgm,
         .is_write = is_write
     };
 
     co = qemu_coroutine_create(throttle_group_restart_queue_entry, &rd);
-    aio_co_enter(blk_get_aio_context(blk), co);
+    aio_co_enter(tgm->aio_context, co);
 }
 
-void throttle_group_restart_blk(BlockBackend *blk)
+void throttle_group_restart_tgm(ThrottleGroupMember *tgm)
 {
-    BlockBackendPublic *blkp = blk_get_public(blk);
-
-    if (blkp->throttle_state) {
-        throttle_group_restart_queue(blk, 0);
-        throttle_group_restart_queue(blk, 1);
+    if (tgm->throttle_state) {
+        throttle_group_restart_queue(tgm, 0);
+        throttle_group_restart_queue(tgm, 1);
     }
 }
 
@@ -420,32 +429,30 @@ void throttle_group_restart_blk(BlockBackend *blk)
  * to throttle_config(), but guarantees atomicity within the
  * throttling group.
  *
- * @blk: a BlockBackend that is a member of the group
+ * @tgm:    a ThrottleGroupMember that is a member of the group
  * @cfg: the configuration to set
  */
-void throttle_group_config(BlockBackend *blk, ThrottleConfig *cfg)
+void throttle_group_config(ThrottleGroupMember *tgm, ThrottleConfig *cfg)
 {
-    BlockBackendPublic *blkp = blk_get_public(blk);
-    ThrottleState *ts = blkp->throttle_state;
+    ThrottleState *ts = tgm->throttle_state;
     ThrottleGroup *tg = container_of(ts, ThrottleGroup, ts);
     qemu_mutex_lock(&tg->lock);
     throttle_config(ts, tg->clock_type, cfg);
     qemu_mutex_unlock(&tg->lock);
 
-    throttle_group_restart_blk(blk);
+    throttle_group_restart_tgm(tgm);
 }
 
 /* Get the throttle configuration from a particular group. Similar to
  * throttle_get_config(), but guarantees atomicity within the
  * throttling group.
  *
- * @blk: a BlockBackend that is a member of the group
+ * @tgm:    a ThrottleGroupMember that is a member of the group
  * @cfg: the configuration will be written here
  */
-void throttle_group_get_config(BlockBackend *blk, ThrottleConfig *cfg)
+void throttle_group_get_config(ThrottleGroupMember *tgm, ThrottleConfig *cfg)
 {
-    BlockBackendPublic *blkp = blk_get_public(blk);
-    ThrottleState *ts = blkp->throttle_state;
+    ThrottleState *ts = tgm->throttle_state;
     ThrottleGroup *tg = container_of(ts, ThrottleGroup, ts);
     qemu_mutex_lock(&tg->lock);
     throttle_get_config(ts, cfg);
@@ -455,13 +462,12 @@ void throttle_group_get_config(BlockBackend *blk, ThrottleConfig *cfg)
 /* ThrottleTimers callback. This wakes up a request that was waiting
  * because it had been throttled.
  *
- * @blk:       the BlockBackend whose request had been throttled
+ * @tgm:       the ThrottleGroupMember whose request had been throttled
  * @is_write:  the type of operation (read/write)
  */
-static void timer_cb(BlockBackend *blk, bool is_write)
+static void timer_cb(ThrottleGroupMember *tgm, bool is_write)
 {
-    BlockBackendPublic *blkp = blk_get_public(blk);
-    ThrottleState *ts = blkp->throttle_state;
+    ThrottleState *ts = tgm->throttle_state;
     ThrottleGroup *tg = container_of(ts, ThrottleGroup, ts);
 
     /* The timer has just been fired, so we can update the flag */
@@ -470,7 +476,7 @@ static void timer_cb(BlockBackend *blk, bool is_write)
     qemu_mutex_unlock(&tg->lock);
 
     /* Run the request that was waiting for this timer */
-    throttle_group_restart_queue(blk, is_write);
+    throttle_group_restart_queue(tgm, is_write);
 }
 
 static void read_timer_cb(void *opaque)
@@ -483,85 +489,445 @@ static void write_timer_cb(void *opaque)
     timer_cb(opaque, true);
 }
 
-/* Register a BlockBackend in the throttling group, also initializing its
- * timers and updating its throttle_state pointer to point to it. If a
+/* Register a ThrottleGroupMember from the throttling group, also initializing
+ * its timers and updating its throttle_state pointer to point to it. If a
  * throttling group with that name does not exist yet, it will be created.
  *
- * @blk:       the BlockBackend to insert
+ * This function edits throttle_groups and must be called under the global
+ * mutex.
+ *
+ * @tgm:       the ThrottleGroupMember to insert
  * @groupname: the name of the group
+ * @ctx:       the AioContext to use
  */
-void throttle_group_register_blk(BlockBackend *blk, const char *groupname)
+void throttle_group_register_tgm(ThrottleGroupMember *tgm,
+                                 const char *groupname,
+                                 AioContext *ctx)
 {
     int i;
-    BlockBackendPublic *blkp = blk_get_public(blk);
     ThrottleState *ts = throttle_group_incref(groupname);
     ThrottleGroup *tg = container_of(ts, ThrottleGroup, ts);
-    blkp->throttle_state = ts;
+
+    tgm->throttle_state = ts;
+    tgm->aio_context = ctx;
 
     qemu_mutex_lock(&tg->lock);
-    /* If the ThrottleGroup is new set this BlockBackend as the token */
+    /* If the ThrottleGroup is new set this ThrottleGroupMember as the token */
     for (i = 0; i < 2; i++) {
         if (!tg->tokens[i]) {
-            tg->tokens[i] = blk;
+            tg->tokens[i] = tgm;
         }
     }
 
-    QLIST_INSERT_HEAD(&tg->head, blkp, round_robin);
+    QLIST_INSERT_HEAD(&tg->head, tgm, round_robin);
 
-    throttle_timers_init(&blkp->throttle_timers,
-                         blk_get_aio_context(blk),
+    throttle_timers_init(&tgm->throttle_timers,
+                         tgm->aio_context,
                          tg->clock_type,
                          read_timer_cb,
                          write_timer_cb,
-                         blk);
+                         tgm);
+    qemu_co_mutex_init(&tgm->throttled_reqs_lock);
+    qemu_co_queue_init(&tgm->throttled_reqs[0]);
+    qemu_co_queue_init(&tgm->throttled_reqs[1]);
 
     qemu_mutex_unlock(&tg->lock);
 }
 
-/* Unregister a BlockBackend from its group, removing it from the list,
+/* Unregister a ThrottleGroupMember from its group, removing it from the list,
  * destroying the timers and setting the throttle_state pointer to NULL.
  *
- * The BlockBackend must not have pending throttled requests, so the caller has
- * to drain them first.
+ * The ThrottleGroupMember must not have pending throttled requests, so the
+ * caller has to drain them first.
  *
  * The group will be destroyed if it's empty after this operation.
  *
- * @blk: the BlockBackend to remove
+ * @tgm the ThrottleGroupMember to remove
  */
-void throttle_group_unregister_blk(BlockBackend *blk)
+void throttle_group_unregister_tgm(ThrottleGroupMember *tgm)
 {
-    BlockBackendPublic *blkp = blk_get_public(blk);
-    ThrottleGroup *tg = container_of(blkp->throttle_state, ThrottleGroup, ts);
+    ThrottleState *ts = tgm->throttle_state;
+    ThrottleGroup *tg = container_of(ts, ThrottleGroup, ts);
+    ThrottleGroupMember *token;
     int i;
 
-    assert(blkp->pending_reqs[0] == 0 && blkp->pending_reqs[1] == 0);
-    assert(qemu_co_queue_empty(&blkp->throttled_reqs[0]));
-    assert(qemu_co_queue_empty(&blkp->throttled_reqs[1]));
+    if (!ts) {
+        /* Discard already unregistered tgm */
+        return;
+    }
+
+    assert(tgm->pending_reqs[0] == 0 && tgm->pending_reqs[1] == 0);
+    assert(qemu_co_queue_empty(&tgm->throttled_reqs[0]));
+    assert(qemu_co_queue_empty(&tgm->throttled_reqs[1]));
 
     qemu_mutex_lock(&tg->lock);
     for (i = 0; i < 2; i++) {
-        if (tg->tokens[i] == blk) {
-            BlockBackend *token = throttle_group_next_blk(blk);
-            /* Take care of the case where this is the last blk in the group */
-            if (token == blk) {
+        if (tg->tokens[i] == tgm) {
+            token = throttle_group_next_tgm(tgm);
+            /* Take care of the case where this is the last tgm in the group */
+            if (token == tgm) {
                 token = NULL;
             }
             tg->tokens[i] = token;
         }
     }
 
-    /* remove the current blk from the list */
-    QLIST_REMOVE(blkp, round_robin);
-    throttle_timers_destroy(&blkp->throttle_timers);
+    /* remove the current tgm from the list */
+    QLIST_REMOVE(tgm, round_robin);
+    throttle_timers_destroy(&tgm->throttle_timers);
     qemu_mutex_unlock(&tg->lock);
 
     throttle_group_unref(&tg->ts);
-    blkp->throttle_state = NULL;
+    tgm->throttle_state = NULL;
+}
+
+void throttle_group_attach_aio_context(ThrottleGroupMember *tgm,
+                                       AioContext *new_context)
+{
+    ThrottleTimers *tt = &tgm->throttle_timers;
+    throttle_timers_attach_aio_context(tt, new_context);
+    tgm->aio_context = new_context;
+}
+
+void throttle_group_detach_aio_context(ThrottleGroupMember *tgm)
+{
+    ThrottleTimers *tt = &tgm->throttle_timers;
+    throttle_timers_detach_aio_context(tt);
+    tgm->aio_context = NULL;
+}
+
+#undef THROTTLE_OPT_PREFIX
+#define THROTTLE_OPT_PREFIX "x-"
+
+/* Helper struct and array for QOM property setter/getter */
+typedef struct {
+    const char *name;
+    BucketType type;
+    enum {
+        AVG,
+        MAX,
+        BURST_LENGTH,
+        IOPS_SIZE,
+    } category;
+} ThrottleParamInfo;
+
+static ThrottleParamInfo properties[] = {
+    {
+        THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_TOTAL,
+        THROTTLE_OPS_TOTAL, AVG,
+    },
+    {
+        THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_TOTAL_MAX,
+        THROTTLE_OPS_TOTAL, MAX,
+    },
+    {
+        THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_TOTAL_MAX_LENGTH,
+        THROTTLE_OPS_TOTAL, BURST_LENGTH,
+    },
+    {
+        THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_READ,
+        THROTTLE_OPS_READ, AVG,
+    },
+    {
+        THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_READ_MAX,
+        THROTTLE_OPS_READ, MAX,
+    },
+    {
+        THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_READ_MAX_LENGTH,
+        THROTTLE_OPS_READ, BURST_LENGTH,
+    },
+    {
+        THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_WRITE,
+        THROTTLE_OPS_WRITE, AVG,
+    },
+    {
+        THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_WRITE_MAX,
+        THROTTLE_OPS_WRITE, MAX,
+    },
+    {
+        THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_WRITE_MAX_LENGTH,
+        THROTTLE_OPS_WRITE, BURST_LENGTH,
+    },
+    {
+        THROTTLE_OPT_PREFIX QEMU_OPT_BPS_TOTAL,
+        THROTTLE_BPS_TOTAL, AVG,
+    },
+    {
+        THROTTLE_OPT_PREFIX QEMU_OPT_BPS_TOTAL_MAX,
+        THROTTLE_BPS_TOTAL, MAX,
+    },
+    {
+        THROTTLE_OPT_PREFIX QEMU_OPT_BPS_TOTAL_MAX_LENGTH,
+        THROTTLE_BPS_TOTAL, BURST_LENGTH,
+    },
+    {
+        THROTTLE_OPT_PREFIX QEMU_OPT_BPS_READ,
+        THROTTLE_BPS_READ, AVG,
+    },
+    {
+        THROTTLE_OPT_PREFIX QEMU_OPT_BPS_READ_MAX,
+        THROTTLE_BPS_READ, MAX,
+    },
+    {
+        THROTTLE_OPT_PREFIX QEMU_OPT_BPS_READ_MAX_LENGTH,
+        THROTTLE_BPS_READ, BURST_LENGTH,
+    },
+    {
+        THROTTLE_OPT_PREFIX QEMU_OPT_BPS_WRITE,
+        THROTTLE_BPS_WRITE, AVG,
+    },
+    {
+        THROTTLE_OPT_PREFIX QEMU_OPT_BPS_WRITE_MAX,
+        THROTTLE_BPS_WRITE, MAX,
+    },
+    {
+        THROTTLE_OPT_PREFIX QEMU_OPT_BPS_WRITE_MAX_LENGTH,
+        THROTTLE_BPS_WRITE, BURST_LENGTH,
+    },
+    {
+        THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_SIZE,
+        0, IOPS_SIZE,
+    }
+};
+
+/* This function edits throttle_groups and must be called under the global
+ * mutex */
+static void throttle_group_obj_init(Object *obj)
+{
+    ThrottleGroup *tg = THROTTLE_GROUP(obj);
+
+    tg->clock_type = QEMU_CLOCK_REALTIME;
+    if (qtest_enabled()) {
+        /* For testing block IO throttling only */
+        tg->clock_type = QEMU_CLOCK_VIRTUAL;
+    }
+    tg->is_initialized = false;
+    qemu_mutex_init(&tg->lock);
+    throttle_init(&tg->ts);
+    QLIST_INIT(&tg->head);
 }
 
+/* This function edits throttle_groups and must be called under the global
+ * mutex */
+static void throttle_group_obj_complete(UserCreatable *obj, Error **errp)
+{
+    ThrottleGroup *tg = THROTTLE_GROUP(obj);
+    ThrottleConfig cfg;
+
+    /* set group name to object id if it exists */
+    if (!tg->name && tg->parent_obj.parent) {
+        tg->name = object_get_canonical_path_component(OBJECT(obj));
+    }
+    /* We must have a group name at this point */
+    assert(tg->name);
+
+    /* error if name is duplicate */
+    if (throttle_group_exists(tg->name)) {
+        error_setg(errp, "A group with this name already exists");
+        return;
+    }
+
+    /* check validity */
+    throttle_get_config(&tg->ts, &cfg);
+    if (!throttle_is_valid(&cfg, errp)) {
+        return;
+    }
+    throttle_config(&tg->ts, tg->clock_type, &cfg);
+    QTAILQ_INSERT_TAIL(&throttle_groups, tg, list);
+    tg->is_initialized = true;
+}
+
+/* This function edits throttle_groups and must be called under the global
+ * mutex */
+static void throttle_group_obj_finalize(Object *obj)
+{
+    ThrottleGroup *tg = THROTTLE_GROUP(obj);
+    if (tg->is_initialized) {
+        QTAILQ_REMOVE(&throttle_groups, tg, list);
+    }
+    qemu_mutex_destroy(&tg->lock);
+    g_free(tg->name);
+}
+
+static void throttle_group_set(Object *obj, Visitor *v, const char * name,
+                               void *opaque, Error **errp)
+
+{
+    ThrottleGroup *tg = THROTTLE_GROUP(obj);
+    ThrottleConfig *cfg;
+    ThrottleParamInfo *info = opaque;
+    Error *local_err = NULL;
+    int64_t value;
+
+    /* If we have finished initialization, don't accept individual property
+     * changes through QOM. Throttle configuration limits must be set in one
+     * transaction, as certain combinations are invalid.
+     */
+    if (tg->is_initialized) {
+        error_setg(&local_err, "Property cannot be set after initialization");
+        goto ret;
+    }
+
+    visit_type_int64(v, name, &value, &local_err);
+    if (local_err) {
+        goto ret;
+    }
+    if (value < 0) {
+        error_setg(&local_err, "Property values cannot be negative");
+        goto ret;
+    }
+
+    cfg = &tg->ts.cfg;
+    switch (info->category) {
+    case AVG:
+        cfg->buckets[info->type].avg = value;
+        break;
+    case MAX:
+        cfg->buckets[info->type].max = value;
+        break;
+    case BURST_LENGTH:
+        if (value > UINT_MAX) {
+            error_setg(&local_err, "%s value must be in the"
+                       "range [0, %u]", info->name, UINT_MAX);
+            goto ret;
+        }
+        cfg->buckets[info->type].burst_length = value;
+        break;
+    case IOPS_SIZE:
+        cfg->op_size = value;
+        break;
+    }
+
+ret:
+    error_propagate(errp, local_err);
+    return;
+
+}
+
+static void throttle_group_get(Object *obj, Visitor *v, const char *name,
+                               void *opaque, Error **errp)
+{
+    ThrottleGroup *tg = THROTTLE_GROUP(obj);
+    ThrottleConfig cfg;
+    ThrottleParamInfo *info = opaque;
+    int64_t value;
+
+    throttle_get_config(&tg->ts, &cfg);
+    switch (info->category) {
+    case AVG:
+        value = cfg.buckets[info->type].avg;
+        break;
+    case MAX:
+        value = cfg.buckets[info->type].max;
+        break;
+    case BURST_LENGTH:
+        value = cfg.buckets[info->type].burst_length;
+        break;
+    case IOPS_SIZE:
+        value = cfg.op_size;
+        break;
+    }
+
+    visit_type_int64(v, name, &value, errp);
+}
+
+static void throttle_group_set_limits(Object *obj, Visitor *v,
+                                      const char *name, void *opaque,
+                                      Error **errp)
+
+{
+    ThrottleGroup *tg = THROTTLE_GROUP(obj);
+    ThrottleConfig cfg;
+    ThrottleLimits arg = { 0 };
+    ThrottleLimits *argp = &arg;
+    Error *local_err = NULL;
+
+    visit_type_ThrottleLimits(v, name, &argp, &local_err);
+    if (local_err) {
+        goto ret;
+    }
+    qemu_mutex_lock(&tg->lock);
+    throttle_get_config(&tg->ts, &cfg);
+    throttle_limits_to_config(argp, &cfg, &local_err);
+    if (local_err) {
+        goto unlock;
+    }
+    throttle_config(&tg->ts, tg->clock_type, &cfg);
+
+unlock:
+    qemu_mutex_unlock(&tg->lock);
+ret:
+    error_propagate(errp, local_err);
+    return;
+}
+
+static void throttle_group_get_limits(Object *obj, Visitor *v,
+                                      const char *name, void *opaque,
+                                      Error **errp)
+{
+    ThrottleGroup *tg = THROTTLE_GROUP(obj);
+    ThrottleConfig cfg;
+    ThrottleLimits arg = { 0 };
+    ThrottleLimits *argp = &arg;
+
+    qemu_mutex_lock(&tg->lock);
+    throttle_get_config(&tg->ts, &cfg);
+    qemu_mutex_unlock(&tg->lock);
+
+    throttle_config_to_limits(&cfg, argp);
+
+    visit_type_ThrottleLimits(v, name, &argp, errp);
+}
+
+static bool throttle_group_can_be_deleted(UserCreatable *uc)
+{
+    return OBJECT(uc)->ref == 1;
+}
+
+static void throttle_group_obj_class_init(ObjectClass *klass, void *class_data)
+{
+    size_t i = 0;
+    UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass);
+
+    ucc->complete = throttle_group_obj_complete;
+    ucc->can_be_deleted = throttle_group_can_be_deleted;
+
+    /* individual properties */
+    for (i = 0; i < sizeof(properties) / sizeof(ThrottleParamInfo); i++) {
+        object_class_property_add(klass,
+                                  properties[i].name,
+                                  "int",
+                                  throttle_group_get,
+                                  throttle_group_set,
+                                  NULL, &properties[i],
+                                  &error_abort);
+    }
+
+    /* ThrottleLimits */
+    object_class_property_add(klass,
+                              "limits", "ThrottleLimits",
+                              throttle_group_get_limits,
+                              throttle_group_set_limits,
+                              NULL, NULL,
+                              &error_abort);
+}
+
+static const TypeInfo throttle_group_info = {
+    .name = TYPE_THROTTLE_GROUP,
+    .parent = TYPE_OBJECT,
+    .class_init = throttle_group_obj_class_init,
+    .instance_size = sizeof(ThrottleGroup),
+    .instance_init = throttle_group_obj_init,
+    .instance_finalize = throttle_group_obj_finalize,
+    .interfaces = (InterfaceInfo[]) {
+        { TYPE_USER_CREATABLE },
+        { }
+    },
+};
+
 static void throttle_groups_init(void)
 {
-    qemu_mutex_init(&throttle_groups_lock);
+    type_register_static(&throttle_group_info);
 }
 
-block_init(throttle_groups_init);
+type_init(throttle_groups_init);
diff --git a/block/throttle.c b/block/throttle.c
new file mode 100644
index 0000000000..5bca76300f
--- /dev/null
+++ b/block/throttle.c
@@ -0,0 +1,237 @@
+/*
+ * QEMU block throttling filter driver infrastructure
+ *
+ * Copyright (c) 2017 Manos Pitsidianakis
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 or
+ * (at your option) version 3 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "qemu/osdep.h"
+#include "block/throttle-groups.h"
+#include "qemu/throttle-options.h"
+#include "qapi/error.h"
+
+static QemuOptsList throttle_opts = {
+    .name = "throttle",
+    .head = QTAILQ_HEAD_INITIALIZER(throttle_opts.head),
+    .desc = {
+        {
+            .name = QEMU_OPT_THROTTLE_GROUP_NAME,
+            .type = QEMU_OPT_STRING,
+            .help = "Name of the throttle group",
+        },
+        { /* end of list */ }
+    },
+};
+
+static int throttle_configure_tgm(BlockDriverState *bs,
+                                  ThrottleGroupMember *tgm,
+                                  QDict *options, Error **errp)
+{
+    int ret;
+    const char *group_name;
+    Error *local_err = NULL;
+    QemuOpts *opts = qemu_opts_create(&throttle_opts, NULL, 0, &error_abort);
+
+    qemu_opts_absorb_qdict(opts, options, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        ret = -EINVAL;
+        goto fin;
+    }
+
+    group_name = qemu_opt_get(opts, QEMU_OPT_THROTTLE_GROUP_NAME);
+    if (!group_name) {
+        error_setg(errp, "Please specify a throttle group");
+        ret = -EINVAL;
+        goto fin;
+    } else if (!throttle_group_exists(group_name)) {
+        error_setg(errp, "Throttle group '%s' does not exist", group_name);
+        ret = -EINVAL;
+        goto fin;
+    }
+
+    /* Register membership to group with name group_name */
+    throttle_group_register_tgm(tgm, group_name, bdrv_get_aio_context(bs));
+    ret = 0;
+fin:
+    qemu_opts_del(opts);
+    return ret;
+}
+
+static int throttle_open(BlockDriverState *bs, QDict *options,
+                         int flags, Error **errp)
+{
+    ThrottleGroupMember *tgm = bs->opaque;
+
+    bs->file = bdrv_open_child(NULL, options, "file", bs,
+                               &child_file, false, errp);
+    if (!bs->file) {
+        return -EINVAL;
+    }
+    bs->supported_write_flags = bs->file->bs->supported_write_flags;
+    bs->supported_zero_flags = bs->file->bs->supported_zero_flags;
+
+    return throttle_configure_tgm(bs, tgm, options, errp);
+}
+
+static void throttle_close(BlockDriverState *bs)
+{
+    ThrottleGroupMember *tgm = bs->opaque;
+    throttle_group_unregister_tgm(tgm);
+}
+
+
+static int64_t throttle_getlength(BlockDriverState *bs)
+{
+    return bdrv_getlength(bs->file->bs);
+}
+
+static int coroutine_fn throttle_co_preadv(BlockDriverState *bs,
+                                           uint64_t offset, uint64_t bytes,
+                                           QEMUIOVector *qiov, int flags)
+{
+
+    ThrottleGroupMember *tgm = bs->opaque;
+    throttle_group_co_io_limits_intercept(tgm, bytes, false);
+
+    return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
+}
+
+static int coroutine_fn throttle_co_pwritev(BlockDriverState *bs,
+                                            uint64_t offset, uint64_t bytes,
+                                            QEMUIOVector *qiov, int flags)
+{
+    ThrottleGroupMember *tgm = bs->opaque;
+    throttle_group_co_io_limits_intercept(tgm, bytes, true);
+
+    return bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags);
+}
+
+static int coroutine_fn throttle_co_pwrite_zeroes(BlockDriverState *bs,
+                                                  int64_t offset, int bytes,
+                                                  BdrvRequestFlags flags)
+{
+    ThrottleGroupMember *tgm = bs->opaque;
+    throttle_group_co_io_limits_intercept(tgm, bytes, true);
+
+    return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
+}
+
+static int coroutine_fn throttle_co_pdiscard(BlockDriverState *bs,
+                                             int64_t offset, int bytes)
+{
+    ThrottleGroupMember *tgm = bs->opaque;
+    throttle_group_co_io_limits_intercept(tgm, bytes, true);
+
+    return bdrv_co_pdiscard(bs->file->bs, offset, bytes);
+}
+
+static int throttle_co_flush(BlockDriverState *bs)
+{
+    return bdrv_co_flush(bs->file->bs);
+}
+
+static void throttle_detach_aio_context(BlockDriverState *bs)
+{
+    ThrottleGroupMember *tgm = bs->opaque;
+    throttle_group_detach_aio_context(tgm);
+}
+
+static void throttle_attach_aio_context(BlockDriverState *bs,
+                                        AioContext *new_context)
+{
+    ThrottleGroupMember *tgm = bs->opaque;
+    throttle_group_attach_aio_context(tgm, new_context);
+}
+
+static int throttle_reopen_prepare(BDRVReopenState *reopen_state,
+                                   BlockReopenQueue *queue, Error **errp)
+{
+    ThrottleGroupMember *tgm;
+
+    assert(reopen_state != NULL);
+    assert(reopen_state->bs != NULL);
+
+    reopen_state->opaque = g_new0(ThrottleGroupMember, 1);
+    tgm = reopen_state->opaque;
+
+    return throttle_configure_tgm(reopen_state->bs, tgm, reopen_state->options,
+            errp);
+}
+
+static void throttle_reopen_commit(BDRVReopenState *reopen_state)
+{
+    ThrottleGroupMember *old_tgm = reopen_state->bs->opaque;
+    ThrottleGroupMember *new_tgm = reopen_state->opaque;
+
+    throttle_group_unregister_tgm(old_tgm);
+    g_free(old_tgm);
+    reopen_state->bs->opaque = new_tgm;
+    reopen_state->opaque = NULL;
+}
+
+static void throttle_reopen_abort(BDRVReopenState *reopen_state)
+{
+    ThrottleGroupMember *tgm = reopen_state->opaque;
+
+    throttle_group_unregister_tgm(tgm);
+    g_free(tgm);
+    reopen_state->opaque = NULL;
+}
+
+static bool throttle_recurse_is_first_non_filter(BlockDriverState *bs,
+                                                 BlockDriverState *candidate)
+{
+    return bdrv_recurse_is_first_non_filter(bs->file->bs, candidate);
+}
+
+static BlockDriver bdrv_throttle = {
+    .format_name                        =   "throttle",
+    .protocol_name                      =   "throttle",
+    .instance_size                      =   sizeof(ThrottleGroupMember),
+
+    .bdrv_file_open                     =   throttle_open,
+    .bdrv_close                         =   throttle_close,
+    .bdrv_co_flush                      =   throttle_co_flush,
+
+    .bdrv_child_perm                    =   bdrv_filter_default_perms,
+
+    .bdrv_getlength                     =   throttle_getlength,
+
+    .bdrv_co_preadv                     =   throttle_co_preadv,
+    .bdrv_co_pwritev                    =   throttle_co_pwritev,
+
+    .bdrv_co_pwrite_zeroes              =   throttle_co_pwrite_zeroes,
+    .bdrv_co_pdiscard                   =   throttle_co_pdiscard,
+
+    .bdrv_recurse_is_first_non_filter   =   throttle_recurse_is_first_non_filter,
+
+    .bdrv_attach_aio_context            =   throttle_attach_aio_context,
+    .bdrv_detach_aio_context            =   throttle_detach_aio_context,
+
+    .bdrv_reopen_prepare                =   throttle_reopen_prepare,
+    .bdrv_reopen_commit                 =   throttle_reopen_commit,
+    .bdrv_reopen_abort                  =   throttle_reopen_abort,
+    .bdrv_co_get_block_status           =   bdrv_co_get_block_status_from_file,
+
+    .is_filter                          =   true,
+};
+
+static void bdrv_throttle_init(void)
+{
+    bdrv_register(&bdrv_throttle);
+}
+
+block_init(bdrv_throttle_init);
diff --git a/blockdev.c b/blockdev.c
index 796beaed94..56a6b24a0b 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -2686,7 +2686,7 @@ void qmp_block_set_io_throttle(BlockIOThrottle *arg, Error **errp)
     if (throttle_enabled(&cfg)) {
         /* Enable I/O limits if they're not enabled yet, otherwise
          * just update the throttling group. */
-        if (!blk_get_public(blk)->throttle_state) {
+        if (!blk_get_public(blk)->throttle_group_member.throttle_state) {
             blk_io_limits_enable(blk,
                                  arg->has_group ? arg->group :
                                  arg->has_device ? arg->device :
@@ -2696,7 +2696,7 @@ void qmp_block_set_io_throttle(BlockIOThrottle *arg, Error **errp)
         }
         /* Set the new throttling configuration */
         blk_set_io_limits(blk, &cfg);
-    } else if (blk_get_public(blk)->throttle_state) {
+    } else if (blk_get_public(blk)->throttle_group_member.throttle_state) {
         /* If all throttling settings are set to 0, disable I/O limits */
         blk_io_limits_disable(blk);
     }
diff --git a/include/block/block.h b/include/block/block.h
index ab80195378..2ad18775af 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -441,7 +441,6 @@ int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only,
 int bdrv_set_read_only(BlockDriverState *bs, bool read_only, Error **errp);
 bool bdrv_is_sg(BlockDriverState *bs);
 bool bdrv_is_inserted(BlockDriverState *bs);
-int bdrv_media_changed(BlockDriverState *bs);
 void bdrv_lock_medium(BlockDriverState *bs, bool locked);
 void bdrv_eject(BlockDriverState *bs, bool eject_flag);
 const char *bdrv_get_format_name(BlockDriverState *bs);
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 7816b43a27..ba4c383393 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -87,7 +87,11 @@ struct BlockDriver {
     const char *format_name;
     int instance_size;
 
-    /* set to true if the BlockDriver is a block filter */
+    /* set to true if the BlockDriver is a block filter. Block filters pass
+     * certain callbacks that refer to data (see block.c) to their bs->file if
+     * the driver doesn't implement them. Drivers that do not wish to forward
+     * must implement them and return -ENOTSUP.
+     */
     bool is_filter;
     /* for snapshots block filter like Quorum can implement the
      * following recursive callback.
@@ -275,7 +279,6 @@ struct BlockDriver {
 
     /* removable device specific */
     bool (*bdrv_is_inserted)(BlockDriverState *bs);
-    int (*bdrv_media_changed)(BlockDriverState *bs);
     void (*bdrv_eject)(BlockDriverState *bs, bool eject_flag);
     void (*bdrv_lock_medium)(BlockDriverState *bs, bool locked);
 
@@ -992,6 +995,24 @@ void bdrv_format_default_perms(BlockDriverState *bs, BdrvChild *c,
                                uint64_t perm, uint64_t shared,
                                uint64_t *nperm, uint64_t *nshared);
 
+/*
+ * Default implementation for drivers to pass bdrv_co_get_block_status() to
+ * their file.
+ */
+int64_t coroutine_fn bdrv_co_get_block_status_from_file(BlockDriverState *bs,
+                                                        int64_t sector_num,
+                                                        int nb_sectors,
+                                                        int *pnum,
+                                                        BlockDriverState **file);
+/*
+ * Default implementation for drivers to pass bdrv_co_get_block_status() to
+ * their backing file.
+ */
+int64_t coroutine_fn bdrv_co_get_block_status_from_backing(BlockDriverState *bs,
+                                                           int64_t sector_num,
+                                                           int nb_sectors,
+                                                           int *pnum,
+                                                           BlockDriverState **file);
 const char *bdrv_get_parent_name(const BlockDriverState *bs);
 void blk_dev_change_media_cb(BlockBackend *blk, bool load, Error **errp);
 bool blk_dev_has_removable_media(BlockBackend *blk);
diff --git a/include/block/throttle-groups.h b/include/block/throttle-groups.h
index d983d34074..e2fd0513c4 100644
--- a/include/block/throttle-groups.h
+++ b/include/block/throttle-groups.h
@@ -28,20 +28,58 @@
 #include "qemu/throttle.h"
 #include "block/block_int.h"
 
-const char *throttle_group_get_name(BlockBackend *blk);
+/* The ThrottleGroupMember structure indicates membership in a ThrottleGroup
+ * and holds related data.
+ */
+
+typedef struct ThrottleGroupMember {
+    AioContext   *aio_context;
+    /* throttled_reqs_lock protects the CoQueues for throttled requests.  */
+    CoMutex      throttled_reqs_lock;
+    CoQueue      throttled_reqs[2];
+
+    /* Nonzero if the I/O limits are currently being ignored; generally
+     * it is zero.  Accessed with atomic operations.
+     */
+    unsigned int io_limits_disabled;
+
+    /* The following fields are protected by the ThrottleGroup lock.
+     * See the ThrottleGroup documentation for details.
+     * throttle_state tells us if I/O limits are configured. */
+    ThrottleState *throttle_state;
+    ThrottleTimers throttle_timers;
+    unsigned       pending_reqs[2];
+    QLIST_ENTRY(ThrottleGroupMember) round_robin;
+
+} ThrottleGroupMember;
+
+#define TYPE_THROTTLE_GROUP "throttle-group"
+#define THROTTLE_GROUP(obj) OBJECT_CHECK(ThrottleGroup, (obj), TYPE_THROTTLE_GROUP)
+
+const char *throttle_group_get_name(ThrottleGroupMember *tgm);
 
 ThrottleState *throttle_group_incref(const char *name);
 void throttle_group_unref(ThrottleState *ts);
 
-void throttle_group_config(BlockBackend *blk, ThrottleConfig *cfg);
-void throttle_group_get_config(BlockBackend *blk, ThrottleConfig *cfg);
+void throttle_group_config(ThrottleGroupMember *tgm, ThrottleConfig *cfg);
+void throttle_group_get_config(ThrottleGroupMember *tgm, ThrottleConfig *cfg);
 
-void throttle_group_register_blk(BlockBackend *blk, const char *groupname);
-void throttle_group_unregister_blk(BlockBackend *blk);
-void throttle_group_restart_blk(BlockBackend *blk);
+void throttle_group_register_tgm(ThrottleGroupMember *tgm,
+                                const char *groupname,
+                                AioContext *ctx);
+void throttle_group_unregister_tgm(ThrottleGroupMember *tgm);
+void throttle_group_restart_tgm(ThrottleGroupMember *tgm);
 
-void coroutine_fn throttle_group_co_io_limits_intercept(BlockBackend *blk,
+void coroutine_fn throttle_group_co_io_limits_intercept(ThrottleGroupMember *tgm,
                                                         unsigned int bytes,
                                                         bool is_write);
+void throttle_group_attach_aio_context(ThrottleGroupMember *tgm,
+                                       AioContext *new_context);
+void throttle_group_detach_aio_context(ThrottleGroupMember *tgm);
+/*
+ * throttle_group_exists() must be called under the global
+ * mutex.
+ */
+bool throttle_group_exists(const char *name);
 
 #endif
diff --git a/include/qemu/throttle-options.h b/include/qemu/throttle-options.h
index 3133d1ca40..3528a8f4a2 100644
--- a/include/qemu/throttle-options.h
+++ b/include/qemu/throttle-options.h
@@ -10,81 +10,103 @@
 #ifndef THROTTLE_OPTIONS_H
 #define THROTTLE_OPTIONS_H
 
+#define QEMU_OPT_IOPS_TOTAL "iops-total"
+#define QEMU_OPT_IOPS_TOTAL_MAX "iops-total-max"
+#define QEMU_OPT_IOPS_TOTAL_MAX_LENGTH "iops-total-max-length"
+#define QEMU_OPT_IOPS_READ "iops-read"
+#define QEMU_OPT_IOPS_READ_MAX "iops-read-max"
+#define QEMU_OPT_IOPS_READ_MAX_LENGTH "iops-read-max-length"
+#define QEMU_OPT_IOPS_WRITE "iops-write"
+#define QEMU_OPT_IOPS_WRITE_MAX "iops-write-max"
+#define QEMU_OPT_IOPS_WRITE_MAX_LENGTH "iops-write-max-length"
+#define QEMU_OPT_BPS_TOTAL "bps-total"
+#define QEMU_OPT_BPS_TOTAL_MAX "bps-total-max"
+#define QEMU_OPT_BPS_TOTAL_MAX_LENGTH "bps-total-max-length"
+#define QEMU_OPT_BPS_READ "bps-read"
+#define QEMU_OPT_BPS_READ_MAX "bps-read-max"
+#define QEMU_OPT_BPS_READ_MAX_LENGTH "bps-read-max-length"
+#define QEMU_OPT_BPS_WRITE "bps-write"
+#define QEMU_OPT_BPS_WRITE_MAX "bps-write-max"
+#define QEMU_OPT_BPS_WRITE_MAX_LENGTH "bps-write-max-length"
+#define QEMU_OPT_IOPS_SIZE "iops-size"
+#define QEMU_OPT_THROTTLE_GROUP_NAME "throttle-group"
+
+#define THROTTLE_OPT_PREFIX "throttling."
 #define THROTTLE_OPTS \
           { \
-            .name = "throttling.iops-total",\
+            .name = THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_TOTAL,\
             .type = QEMU_OPT_NUMBER,\
             .help = "limit total I/O operations per second",\
         },{ \
-            .name = "throttling.iops-read",\
+            .name = THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_READ,\
             .type = QEMU_OPT_NUMBER,\
             .help = "limit read operations per second",\
         },{ \
-            .name = "throttling.iops-write",\
+            .name = THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_WRITE,\
             .type = QEMU_OPT_NUMBER,\
             .help = "limit write operations per second",\
         },{ \
-            .name = "throttling.bps-total",\
+            .name = THROTTLE_OPT_PREFIX QEMU_OPT_BPS_TOTAL,\
             .type = QEMU_OPT_NUMBER,\
             .help = "limit total bytes per second",\
         },{ \
-            .name = "throttling.bps-read",\
+            .name = THROTTLE_OPT_PREFIX QEMU_OPT_BPS_READ,\
             .type = QEMU_OPT_NUMBER,\
             .help = "limit read bytes per second",\
         },{ \
-            .name = "throttling.bps-write",\
+            .name = THROTTLE_OPT_PREFIX QEMU_OPT_BPS_WRITE,\
             .type = QEMU_OPT_NUMBER,\
             .help = "limit write bytes per second",\
         },{ \
-            .name = "throttling.iops-total-max",\
+            .name = THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_TOTAL_MAX,\
             .type = QEMU_OPT_NUMBER,\
             .help = "I/O operations burst",\
         },{ \
-            .name = "throttling.iops-read-max",\
+            .name = THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_READ_MAX,\
             .type = QEMU_OPT_NUMBER,\
             .help = "I/O operations read burst",\
         },{ \
-            .name = "throttling.iops-write-max",\
+            .name = THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_WRITE_MAX,\
             .type = QEMU_OPT_NUMBER,\
             .help = "I/O operations write burst",\
         },{ \
-            .name = "throttling.bps-total-max",\
+            .name = THROTTLE_OPT_PREFIX QEMU_OPT_BPS_TOTAL_MAX,\
             .type = QEMU_OPT_NUMBER,\
             .help = "total bytes burst",\
         },{ \
-            .name = "throttling.bps-read-max",\
+            .name = THROTTLE_OPT_PREFIX QEMU_OPT_BPS_READ_MAX,\
             .type = QEMU_OPT_NUMBER,\
             .help = "total bytes read burst",\
         },{ \
-            .name = "throttling.bps-write-max",\
+            .name = THROTTLE_OPT_PREFIX QEMU_OPT_BPS_WRITE_MAX,\
             .type = QEMU_OPT_NUMBER,\
             .help = "total bytes write burst",\
         },{ \
-            .name = "throttling.iops-total-max-length",\
+            .name = THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_TOTAL_MAX_LENGTH,\
             .type = QEMU_OPT_NUMBER,\
             .help = "length of the iops-total-max burst period, in seconds",\
         },{ \
-            .name = "throttling.iops-read-max-length",\
+            .name = THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_READ_MAX_LENGTH,\
             .type = QEMU_OPT_NUMBER,\
             .help = "length of the iops-read-max burst period, in seconds",\
         },{ \
-            .name = "throttling.iops-write-max-length",\
+            .name = THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_WRITE_MAX_LENGTH,\
             .type = QEMU_OPT_NUMBER,\
             .help = "length of the iops-write-max burst period, in seconds",\
         },{ \
-            .name = "throttling.bps-total-max-length",\
+            .name = THROTTLE_OPT_PREFIX QEMU_OPT_BPS_TOTAL_MAX_LENGTH,\
             .type = QEMU_OPT_NUMBER,\
             .help = "length of the bps-total-max burst period, in seconds",\
         },{ \
-            .name = "throttling.bps-read-max-length",\
+            .name = THROTTLE_OPT_PREFIX QEMU_OPT_BPS_READ_MAX_LENGTH,\
             .type = QEMU_OPT_NUMBER,\
             .help = "length of the bps-read-max burst period, in seconds",\
         },{ \
-            .name = "throttling.bps-write-max-length",\
+            .name = THROTTLE_OPT_PREFIX QEMU_OPT_BPS_WRITE_MAX_LENGTH,\
             .type = QEMU_OPT_NUMBER,\
             .help = "length of the bps-write-max burst period, in seconds",\
         },{ \
-            .name = "throttling.iops-size",\
+            .name = THROTTLE_OPT_PREFIX QEMU_OPT_IOPS_SIZE,\
             .type = QEMU_OPT_NUMBER,\
             .help = "when limiting by iops max size of an I/O in bytes",\
         }
diff --git a/include/qemu/throttle.h b/include/qemu/throttle.h
index 8e01885d29..8c93237866 100644
--- a/include/qemu/throttle.h
+++ b/include/qemu/throttle.h
@@ -152,5 +152,8 @@ bool throttle_schedule_timer(ThrottleState *ts,
                              bool is_write);
 
 void throttle_account(ThrottleState *ts, bool is_write, uint64_t size);
+void throttle_limits_to_config(ThrottleLimits *arg, ThrottleConfig *cfg,
+                               Error **errp);
+void throttle_config_to_limits(ThrottleConfig *cfg, ThrottleLimits *var);
 
 #endif
diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index aadc733daf..c4e52a5fa3 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -70,24 +70,10 @@ typedef struct BlockDevOps {
 
 /* This struct is embedded in (the private) BlockBackend struct and contains
  * fields that must be public. This is in particular for QLIST_ENTRY() and
- * friends so that BlockBackends can be kept in lists outside block-backend.c */
+ * friends so that BlockBackends can be kept in lists outside block-backend.c
+ * */
 typedef struct BlockBackendPublic {
-    /* throttled_reqs_lock protects the CoQueues for throttled requests.  */
-    CoMutex      throttled_reqs_lock;
-    CoQueue      throttled_reqs[2];
-
-    /* Nonzero if the I/O limits are currently being ignored; generally
-     * it is zero.  Accessed with atomic operations.
-     */
-    unsigned int io_limits_disabled;
-
-    /* The following fields are protected by the ThrottleGroup lock.
-     * See the ThrottleGroup documentation for details.
-     * throttle_state tells us if I/O limits are configured. */
-    ThrottleState *throttle_state;
-    ThrottleTimers throttle_timers;
-    unsigned       pending_reqs[2];
-    QLIST_ENTRY(BlockBackendPublic) round_robin;
+    ThrottleGroupMember throttle_group_member;
 } BlockBackendPublic;
 
 BlockBackend *blk_new(uint64_t perm, uint64_t shared_perm);
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 28abb9e6cf..bb11815608 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -1906,6 +1906,54 @@
             '*iops_size': 'int', '*group': 'str' } }
 
 ##
+# @ThrottleLimits:
+#
+# Limit parameters for throttling.
+# Since some limit combinations are illegal, limits should always be set in one
+# transaction. All fields are optional. When setting limits, if a field is
+# missing the current value is not changed.
+#
+# @iops-total:             limit total I/O operations per second
+# @iops-total-max:         I/O operations burst
+# @iops-total-max-length:  length of the iops-total-max burst period, in seconds
+#                          It must only be set if @iops-total-max is set as well.
+# @iops-read:              limit read operations per second
+# @iops-read-max:          I/O operations read burst
+# @iops-read-max-length:   length of the iops-read-max burst period, in seconds
+#                          It must only be set if @iops-read-max is set as well.
+# @iops-write:             limit write operations per second
+# @iops-write-max:         I/O operations write burst
+# @iops-write-max-length:  length of the iops-write-max burst period, in seconds
+#                          It must only be set if @iops-write-max is set as well.
+# @bps-total:              limit total bytes per second
+# @bps-total-max:          total bytes burst
+# @bps-total-max-length:   length of the bps-total-max burst period, in seconds.
+#                          It must only be set if @bps-total-max is set as well.
+# @bps-read:               limit read bytes per second
+# @bps-read-max:           total bytes read burst
+# @bps-read-max-length:    length of the bps-read-max burst period, in seconds
+#                          It must only be set if @bps-read-max is set as well.
+# @bps-write:              limit write bytes per second
+# @bps-write-max:          total bytes write burst
+# @bps-write-max-length:   length of the bps-write-max burst period, in seconds
+#                          It must only be set if @bps-write-max is set as well.
+# @iops-size:              when limiting by iops max size of an I/O in bytes
+#
+# Since: 2.11
+##
+{ 'struct': 'ThrottleLimits',
+  'data': { '*iops-total' : 'int', '*iops-total-max' : 'int',
+            '*iops-total-max-length' : 'int', '*iops-read' : 'int',
+            '*iops-read-max' : 'int', '*iops-read-max-length' : 'int',
+            '*iops-write' : 'int', '*iops-write-max' : 'int',
+            '*iops-write-max-length' : 'int', '*bps-total' : 'int',
+            '*bps-total-max' : 'int', '*bps-total-max-length' : 'int',
+            '*bps-read' : 'int', '*bps-read-max' : 'int',
+            '*bps-read-max-length' : 'int', '*bps-write' : 'int',
+            '*bps-write-max' : 'int', '*bps-write-max-length' : 'int',
+            '*iops-size' : 'int' } }
+
+##
 # @block-stream:
 #
 # Copy data from a backing file into a block device.
@@ -2175,6 +2223,7 @@
 # Drivers that are supported in block device operations.
 #
 # @vxhs: Since 2.10
+# @throttle: Since 2.11
 #
 # Since: 2.9
 ##
@@ -2184,7 +2233,7 @@
             'host_device', 'http', 'https', 'iscsi', 'luks', 'nbd', 'nfs',
             'null-aio', 'null-co', 'parallels', 'qcow', 'qcow2', 'qed',
             'quorum', 'raw', 'rbd', 'replication', 'sheepdog', 'ssh',
-            'vdi', 'vhdx', 'vmdk', 'vpc', 'vvfat', 'vxhs' ] }
+            'throttle', 'vdi', 'vhdx', 'vmdk', 'vpc', 'vvfat', 'vxhs' ] }
 
 ##
 # @BlockdevOptionsFile:
@@ -3048,6 +3097,20 @@
             '*tls-creds': 'str' } }
 
 ##
+# @BlockdevOptionsThrottle:
+#
+# Driver specific block device options for the throttle driver
+#
+# @throttle-group:   the name of the throttle-group object to use. It
+#                    must already exist.
+# @file:             reference to or definition of the data source block device
+# Since: 2.11
+##
+{ 'struct': 'BlockdevOptionsThrottle',
+  'data': { 'throttle-group': 'str',
+            'file' : 'BlockdevRef'
+             } }
+##
 # @BlockdevOptions:
 #
 # Options for creating a block device.  Many options are available for all
@@ -3108,6 +3171,7 @@
       'replication':'BlockdevOptionsReplication',
       'sheepdog':   'BlockdevOptionsSheepdog',
       'ssh':        'BlockdevOptionsSsh',
+      'throttle':   'BlockdevOptionsThrottle',
       'vdi':        'BlockdevOptionsGenericFormat',
       'vhdx':       'BlockdevOptionsGenericFormat',
       'vmdk':       'BlockdevOptionsGenericCOWFormat',
diff --git a/tests/qemu-iotests/184 b/tests/qemu-iotests/184
new file mode 100755
index 0000000000..704f38f936
--- /dev/null
+++ b/tests/qemu-iotests/184
@@ -0,0 +1,205 @@
+#!/bin/bash
+#
+# Test I/O throttle block filter driver interface
+#
+# Copyright (C) 2017 Manos Pitsidianakis
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+# creator
+owner="Manos Pitsidianakis"
+
+seq=`basename $0`
+echo "QA output created by $seq"
+
+here=`pwd`
+status=1	# failure is the default!
+
+_cleanup()
+{
+    _cleanup_test_img
+}
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+# get standard environment, filters and checks
+. ./common.rc
+. ./common.filter
+
+_supported_fmt qcow2
+_supported_proto file
+_supported_os Linux
+
+function do_run_qemu()
+{
+    echo Testing: "$@" | _filter_imgfmt
+    $QEMU -nographic -qmp-pretty stdio -serial none "$@"
+    echo
+}
+
+function run_qemu()
+{
+    do_run_qemu "$@" 2>&1 | _filter_testdir | _filter_qemu | _filter_qmp\
+                          | _filter_qemu_io | _filter_generated_node_ids
+}
+
+_make_test_img 64M
+test_throttle=$($QEMU_IMG --help|grep throttle)
+[ "$test_throttle" = "" ] && _supported_fmt throttle
+
+echo
+echo "== checking interface =="
+
+run_qemu <<EOF
+{ "execute": "qmp_capabilities" }
+{ "execute": "blockdev-add",
+  "arguments": {
+    "driver": "$IMGFMT",
+    "node-name": "disk0",
+    "file": {
+      "driver": "file",
+      "filename": "$TEST_IMG"
+    }
+  }
+}
+{ "execute": "object-add",
+  "arguments": {
+    "qom-type": "throttle-group",
+    "id": "group0",
+    "props": {
+      "limits" : {
+        "iops-total": 1000
+      }
+    }
+  }
+}
+{ "execute": "blockdev-add",
+  "arguments": {
+    "driver": "throttle",
+    "node-name": "throttle0",
+    "throttle-group": "group0",
+    "file": "disk0"
+  }
+}
+{ "execute": "query-named-block-nodes" }
+{ "execute": "query-block" }
+{ "execute": "quit" }
+EOF
+
+echo
+echo "== property changes in ThrottleGroup =="
+
+run_qemu <<EOF
+{ "execute": "qmp_capabilities" }
+{ "execute": "object-add",
+  "arguments": {
+    "qom-type": "throttle-group",
+    "id": "group0",
+    "props" : {
+      "limits": {
+          "iops-total": 1000
+      }
+    }
+  }
+}
+{ "execute" : "qom-get",
+  "arguments" : {
+    "path" : "group0",
+    "property" : "limits"
+  }
+}
+{ "execute" : "qom-set",
+    "arguments" : {
+        "path" : "group0",
+        "property" : "limits",
+        "value" : {
+            "iops-total" : 0
+        }
+    }
+}
+{ "execute" : "qom-get",
+  "arguments" : {
+    "path" : "group0",
+    "property" : "limits"
+  }
+}
+{ "execute": "quit" }
+EOF
+
+echo
+echo "== object creation/set errors  =="
+
+run_qemu <<EOF
+{ "execute": "qmp_capabilities" }
+{ "execute": "object-add",
+  "arguments": {
+    "qom-type": "throttle-group",
+    "id": "group0",
+    "props" : {
+      "limits": {
+          "iops-total": 1000
+      }
+    }
+  }
+}
+{ "execute" : "qom-set",
+  "arguments" : {
+    "path" : "group0",
+    "property" : "x-iops-total",
+    "value" : 0
+  }
+}
+{ "execute" : "qom-set",
+    "arguments" : {
+        "path" : "group0",
+        "property" : "limits",
+        "value" : {
+            "iops-total" : 10,
+            "iops-read" : 10
+        }
+    }
+}
+{ "execute": "quit" }
+EOF
+
+echo
+echo "== don't specify group =="
+
+run_qemu <<EOF
+{ "execute": "qmp_capabilities" }
+{ "execute": "blockdev-add",
+  "arguments": {
+    "driver": "$IMGFMT",
+    "node-name": "disk0",
+    "file": {
+      "driver": "file",
+      "filename": "$TEST_IMG"
+    }
+  }
+}
+{ "execute": "blockdev-add",
+  "arguments": {
+    "driver": "throttle",
+    "node-name": "throttle0",
+    "file": "disk0"
+  }
+}
+{ "execute": "quit" }
+EOF
+
+echo
+# success, all done
+echo "*** done"
+rm -f $seq.full
+status=0
diff --git a/tests/qemu-iotests/184.out b/tests/qemu-iotests/184.out
new file mode 100644
index 0000000000..0aed1a2220
--- /dev/null
+++ b/tests/qemu-iotests/184.out
@@ -0,0 +1,302 @@
+QA output created by 184
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
+
+== checking interface ==
+Testing:
+{
+    QMP_VERSION
+}
+{
+    "return": {
+    }
+}
+{
+    "return": {
+    }
+}
+{
+    "return": {
+    }
+}
+{
+    "return": {
+    }
+}
+{
+    "return": [
+        {
+            "iops_rd": 0,
+            "detect_zeroes": "off",
+            "image": {
+                "virtual-size": 67108864,
+                "filename": "json:{\"throttle-group\": \"group0\", \"driver\": \"throttle\", \"file\": {\"driver\": \"qcow2\", \"file\": {\"driver\": \"file\", \"filename\": \"TEST_DIR/t.qcow2\"}}}",
+                "cluster-size": 65536,
+                "format": "throttle",
+                "actual-size": 200704,
+                "dirty-flag": false
+            },
+            "iops_wr": 0,
+            "ro": false,
+            "node-name": "throttle0",
+            "backing_file_depth": 0,
+            "drv": "throttle",
+            "iops": 0,
+            "bps_wr": 0,
+            "write_threshold": 0,
+            "encrypted": false,
+            "bps": 0,
+            "bps_rd": 0,
+            "cache": {
+                "no-flush": false,
+                "direct": false,
+                "writeback": true
+            },
+            "file": "json:{\"throttle-group\": \"group0\", \"driver\": \"throttle\", \"file\": {\"driver\": \"qcow2\", \"file\": {\"driver\": \"file\", \"filename\": \"TEST_DIR/t.qcow2\"}}}",
+            "encryption_key_missing": false
+        },
+        {
+            "iops_rd": 0,
+            "detect_zeroes": "off",
+            "image": {
+                "virtual-size": 67108864,
+                "filename": "TEST_DIR/t.qcow2",
+                "cluster-size": 65536,
+                "format": "qcow2",
+                "actual-size": 200704,
+                "format-specific": {
+                    "type": "qcow2",
+                    "data": {
+                        "compat": "1.1",
+                        "lazy-refcounts": false,
+                        "refcount-bits": 16,
+                        "corrupt": false
+                    }
+                },
+                "dirty-flag": false
+            },
+            "iops_wr": 0,
+            "ro": false,
+            "node-name": "disk0",
+            "backing_file_depth": 0,
+            "drv": "qcow2",
+            "iops": 0,
+            "bps_wr": 0,
+            "write_threshold": 0,
+            "encrypted": false,
+            "bps": 0,
+            "bps_rd": 0,
+            "cache": {
+                "no-flush": false,
+                "direct": false,
+                "writeback": true
+            },
+            "file": "TEST_DIR/t.qcow2",
+            "encryption_key_missing": false
+        },
+        {
+            "iops_rd": 0,
+            "detect_zeroes": "off",
+            "image": {
+                "virtual-size": 197120,
+                "filename": "TEST_DIR/t.qcow2",
+                "format": "file",
+                "actual-size": 200704,
+                "dirty-flag": false
+            },
+            "iops_wr": 0,
+            "ro": false,
+            "node-name": "NODE_NAME",
+            "backing_file_depth": 0,
+            "drv": "file",
+            "iops": 0,
+            "bps_wr": 0,
+            "write_threshold": 0,
+            "encrypted": false,
+            "bps": 0,
+            "bps_rd": 0,
+            "cache": {
+                "no-flush": false,
+                "direct": false,
+                "writeback": true
+            },
+            "file": "TEST_DIR/t.qcow2",
+            "encryption_key_missing": false
+        }
+    ]
+}
+{
+    "return": [
+    ]
+}
+{
+    "return": {
+    }
+}
+{
+    "timestamp": {
+        "seconds":  TIMESTAMP,
+        "microseconds":  TIMESTAMP
+    },
+    "event": "SHUTDOWN",
+    "data": {
+        "guest": false
+    }
+}
+
+
+== property changes in ThrottleGroup ==
+Testing:
+{
+    QMP_VERSION
+}
+{
+    "return": {
+    }
+}
+{
+    "return": {
+    }
+}
+{
+    "return": {
+        "bps-read-max-length": 1,
+        "iops-read-max-length": 1,
+        "bps-read-max": 0,
+        "bps-total": 0,
+        "iops-total-max-length": 1,
+        "iops-total": 1000,
+        "iops-write-max": 0,
+        "bps-write": 0,
+        "bps-total-max": 0,
+        "bps-write-max": 0,
+        "iops-size": 0,
+        "iops-read": 0,
+        "iops-write-max-length": 1,
+        "iops-write": 0,
+        "bps-total-max-length": 1,
+        "iops-read-max": 0,
+        "bps-read": 0,
+        "bps-write-max-length": 1,
+        "iops-total-max": 0
+    }
+}
+{
+    "return": {
+    }
+}
+{
+    "return": {
+        "bps-read-max-length": 1,
+        "iops-read-max-length": 1,
+        "bps-read-max": 0,
+        "bps-total": 0,
+        "iops-total-max-length": 1,
+        "iops-total": 0,
+        "iops-write-max": 0,
+        "bps-write": 0,
+        "bps-total-max": 0,
+        "bps-write-max": 0,
+        "iops-size": 0,
+        "iops-read": 0,
+        "iops-write-max-length": 1,
+        "iops-write": 0,
+        "bps-total-max-length": 1,
+        "iops-read-max": 0,
+        "bps-read": 0,
+        "bps-write-max-length": 1,
+        "iops-total-max": 0
+    }
+}
+{
+    "return": {
+    }
+}
+{
+    "timestamp": {
+        "seconds":  TIMESTAMP,
+        "microseconds":  TIMESTAMP
+    },
+    "event": "SHUTDOWN",
+    "data": {
+        "guest": false
+    }
+}
+
+
+== object creation/set errors  ==
+Testing:
+{
+    QMP_VERSION
+}
+{
+    "return": {
+    }
+}
+{
+    "return": {
+    }
+}
+{
+    "error": {
+        "class": "GenericError",
+        "desc": "Property cannot be set after initialization"
+    }
+}
+{
+    "error": {
+        "class": "GenericError",
+        "desc": "bps/iops/max total values and read/write values cannot be used at the same time"
+    }
+}
+{
+    "return": {
+    }
+}
+{
+    "timestamp": {
+        "seconds":  TIMESTAMP,
+        "microseconds":  TIMESTAMP
+    },
+    "event": "SHUTDOWN",
+    "data": {
+        "guest": false
+    }
+}
+
+
+== don't specify group ==
+Testing:
+{
+    QMP_VERSION
+}
+{
+    "return": {
+    }
+}
+{
+    "return": {
+    }
+}
+{
+    "error": {
+        "class": "GenericError",
+        "desc": "Parameter 'throttle-group' is missing"
+    }
+}
+{
+    "return": {
+    }
+}
+{
+    "timestamp": {
+        "seconds":  TIMESTAMP,
+        "microseconds":  TIMESTAMP
+    },
+    "event": "SHUTDOWN",
+    "data": {
+        "guest": false
+    }
+}
+
+
+*** done
diff --git a/tests/qemu-iotests/group b/tests/qemu-iotests/group
index 4bd5017008..94e764865a 100644
--- a/tests/qemu-iotests/group
+++ b/tests/qemu-iotests/group
@@ -180,6 +180,7 @@
 181 rw auto migration
 182 rw auto quick
 183 rw auto migration
+184 rw auto quick
 185 rw auto
 186 rw auto
 187 rw auto
diff --git a/tests/test-throttle.c b/tests/test-throttle.c
index bf7a5a648a..948a42c991 100644
--- a/tests/test-throttle.c
+++ b/tests/test-throttle.c
@@ -24,8 +24,9 @@
 static AioContext     *ctx;
 static LeakyBucket    bkt;
 static ThrottleConfig cfg;
+static ThrottleGroupMember tgm;
 static ThrottleState  ts;
-static ThrottleTimers tt;
+static ThrottleTimers *tt;
 
 /* useful function */
 static bool double_cmp(double x, double y)
@@ -153,19 +154,21 @@ static void test_init(void)
 {
     int i;
 
+    tt = &tgm.throttle_timers;
+
     /* fill the structures with crap */
     memset(&ts, 1, sizeof(ts));
-    memset(&tt, 1, sizeof(tt));
+    memset(tt, 1, sizeof(*tt));
 
     /* init structures */
     throttle_init(&ts);
-    throttle_timers_init(&tt, ctx, QEMU_CLOCK_VIRTUAL,
+    throttle_timers_init(tt, ctx, QEMU_CLOCK_VIRTUAL,
                          read_timer_cb, write_timer_cb, &ts);
 
     /* check initialized fields */
-    g_assert(tt.clock_type == QEMU_CLOCK_VIRTUAL);
-    g_assert(tt.timers[0]);
-    g_assert(tt.timers[1]);
+    g_assert(tt->clock_type == QEMU_CLOCK_VIRTUAL);
+    g_assert(tt->timers[0]);
+    g_assert(tt->timers[1]);
 
     /* check other fields where cleared */
     g_assert(!ts.previous_leak);
@@ -176,18 +179,18 @@ static void test_init(void)
         g_assert(!ts.cfg.buckets[i].level);
     }
 
-    throttle_timers_destroy(&tt);
+    throttle_timers_destroy(tt);
 }
 
 static void test_destroy(void)
 {
     int i;
     throttle_init(&ts);
-    throttle_timers_init(&tt, ctx, QEMU_CLOCK_VIRTUAL,
+    throttle_timers_init(tt, ctx, QEMU_CLOCK_VIRTUAL,
                          read_timer_cb, write_timer_cb, &ts);
-    throttle_timers_destroy(&tt);
+    throttle_timers_destroy(tt);
     for (i = 0; i < 2; i++) {
-        g_assert(!tt.timers[i]);
+        g_assert(!tt->timers[i]);
     }
 }
 
@@ -224,7 +227,7 @@ static void test_config_functions(void)
     orig_cfg.op_size = 1;
 
     throttle_init(&ts);
-    throttle_timers_init(&tt, ctx, QEMU_CLOCK_VIRTUAL,
+    throttle_timers_init(tt, ctx, QEMU_CLOCK_VIRTUAL,
                          read_timer_cb, write_timer_cb, &ts);
     /* structure reset by throttle_init previous_leak should be null */
     g_assert(!ts.previous_leak);
@@ -236,7 +239,7 @@ static void test_config_functions(void)
     /* get back the fixed configuration */
     throttle_get_config(&ts, &final_cfg);
 
-    throttle_timers_destroy(&tt);
+    throttle_timers_destroy(tt);
 
     g_assert(final_cfg.buckets[THROTTLE_BPS_TOTAL].avg == 153);
     g_assert(final_cfg.buckets[THROTTLE_BPS_READ].avg  == 56);
@@ -494,45 +497,45 @@ static void test_have_timer(void)
 {
     /* zero structures */
     memset(&ts, 0, sizeof(ts));
-    memset(&tt, 0, sizeof(tt));
+    memset(tt, 0, sizeof(*tt));
 
     /* no timer set should return false */
-    g_assert(!throttle_timers_are_initialized(&tt));
+    g_assert(!throttle_timers_are_initialized(tt));
 
     /* init structures */
     throttle_init(&ts);
-    throttle_timers_init(&tt, ctx, QEMU_CLOCK_VIRTUAL,
+    throttle_timers_init(tt, ctx, QEMU_CLOCK_VIRTUAL,
                          read_timer_cb, write_timer_cb, &ts);
 
     /* timer set by init should return true */
-    g_assert(throttle_timers_are_initialized(&tt));
+    g_assert(throttle_timers_are_initialized(tt));
 
-    throttle_timers_destroy(&tt);
+    throttle_timers_destroy(tt);
 }
 
 static void test_detach_attach(void)
 {
     /* zero structures */
     memset(&ts, 0, sizeof(ts));
-    memset(&tt, 0, sizeof(tt));
+    memset(tt, 0, sizeof(*tt));
 
     /* init the structure */
     throttle_init(&ts);
-    throttle_timers_init(&tt, ctx, QEMU_CLOCK_VIRTUAL,
+    throttle_timers_init(tt, ctx, QEMU_CLOCK_VIRTUAL,
                          read_timer_cb, write_timer_cb, &ts);
 
     /* timer set by init should return true */
-    g_assert(throttle_timers_are_initialized(&tt));
+    g_assert(throttle_timers_are_initialized(tt));
 
     /* timer should no longer exist after detaching */
-    throttle_timers_detach_aio_context(&tt);
-    g_assert(!throttle_timers_are_initialized(&tt));
+    throttle_timers_detach_aio_context(tt);
+    g_assert(!throttle_timers_are_initialized(tt));
 
     /* timer should exist again after attaching */
-    throttle_timers_attach_aio_context(&tt, ctx);
-    g_assert(throttle_timers_are_initialized(&tt));
+    throttle_timers_attach_aio_context(tt, ctx);
+    g_assert(throttle_timers_are_initialized(tt));
 
-    throttle_timers_destroy(&tt);
+    throttle_timers_destroy(tt);
 }
 
 static bool do_test_accounting(bool is_ops, /* are we testing bps or ops */
@@ -561,7 +564,7 @@ static bool do_test_accounting(bool is_ops, /* are we testing bps or ops */
     cfg.op_size = op_size;
 
     throttle_init(&ts);
-    throttle_timers_init(&tt, ctx, QEMU_CLOCK_VIRTUAL,
+    throttle_timers_init(tt, ctx, QEMU_CLOCK_VIRTUAL,
                          read_timer_cb, write_timer_cb, &ts);
     throttle_config(&ts, QEMU_CLOCK_VIRTUAL, &cfg);
 
@@ -588,7 +591,7 @@ static bool do_test_accounting(bool is_ops, /* are we testing bps or ops */
         return false;
     }
 
-    throttle_timers_destroy(&tt);
+    throttle_timers_destroy(tt);
 
     return true;
 }
@@ -669,6 +672,7 @@ static void test_groups(void)
     ThrottleConfig cfg1, cfg2;
     BlockBackend *blk1, *blk2, *blk3;
     BlockBackendPublic *blkp1, *blkp2, *blkp3;
+    ThrottleGroupMember *tgm1, *tgm2, *tgm3;
 
     /* No actual I/O is performed on these devices */
     blk1 = blk_new(0, BLK_PERM_ALL);
@@ -679,21 +683,25 @@ static void test_groups(void)
     blkp2 = blk_get_public(blk2);
     blkp3 = blk_get_public(blk3);
 
-    g_assert(blkp1->throttle_state == NULL);
-    g_assert(blkp2->throttle_state == NULL);
-    g_assert(blkp3->throttle_state == NULL);
+    tgm1 = &blkp1->throttle_group_member;
+    tgm2 = &blkp2->throttle_group_member;
+    tgm3 = &blkp3->throttle_group_member;
+
+    g_assert(tgm1->throttle_state == NULL);
+    g_assert(tgm2->throttle_state == NULL);
+    g_assert(tgm3->throttle_state == NULL);
 
-    throttle_group_register_blk(blk1, "bar");
-    throttle_group_register_blk(blk2, "foo");
-    throttle_group_register_blk(blk3, "bar");
+    throttle_group_register_tgm(tgm1, "bar", blk_get_aio_context(blk1));
+    throttle_group_register_tgm(tgm2, "foo", blk_get_aio_context(blk2));
+    throttle_group_register_tgm(tgm3, "bar", blk_get_aio_context(blk3));
 
-    g_assert(blkp1->throttle_state != NULL);
-    g_assert(blkp2->throttle_state != NULL);
-    g_assert(blkp3->throttle_state != NULL);
+    g_assert(tgm1->throttle_state != NULL);
+    g_assert(tgm2->throttle_state != NULL);
+    g_assert(tgm3->throttle_state != NULL);
 
-    g_assert(!strcmp(throttle_group_get_name(blk1), "bar"));
-    g_assert(!strcmp(throttle_group_get_name(blk2), "foo"));
-    g_assert(blkp1->throttle_state == blkp3->throttle_state);
+    g_assert(!strcmp(throttle_group_get_name(tgm1), "bar"));
+    g_assert(!strcmp(throttle_group_get_name(tgm2), "foo"));
+    g_assert(tgm1->throttle_state == tgm3->throttle_state);
 
     /* Setting the config of a group member affects the whole group */
     throttle_config_init(&cfg1);
@@ -701,29 +709,29 @@ static void test_groups(void)
     cfg1.buckets[THROTTLE_BPS_WRITE].avg = 285000;
     cfg1.buckets[THROTTLE_OPS_READ].avg  = 20000;
     cfg1.buckets[THROTTLE_OPS_WRITE].avg = 12000;
-    throttle_group_config(blk1, &cfg1);
+    throttle_group_config(tgm1, &cfg1);
 
-    throttle_group_get_config(blk1, &cfg1);
-    throttle_group_get_config(blk3, &cfg2);
+    throttle_group_get_config(tgm1, &cfg1);
+    throttle_group_get_config(tgm3, &cfg2);
     g_assert(!memcmp(&cfg1, &cfg2, sizeof(cfg1)));
 
     cfg2.buckets[THROTTLE_BPS_READ].avg  = 4547;
     cfg2.buckets[THROTTLE_BPS_WRITE].avg = 1349;
     cfg2.buckets[THROTTLE_OPS_READ].avg  = 123;
     cfg2.buckets[THROTTLE_OPS_WRITE].avg = 86;
-    throttle_group_config(blk3, &cfg1);
+    throttle_group_config(tgm3, &cfg1);
 
-    throttle_group_get_config(blk1, &cfg1);
-    throttle_group_get_config(blk3, &cfg2);
+    throttle_group_get_config(tgm1, &cfg1);
+    throttle_group_get_config(tgm3, &cfg2);
     g_assert(!memcmp(&cfg1, &cfg2, sizeof(cfg1)));
 
-    throttle_group_unregister_blk(blk1);
-    throttle_group_unregister_blk(blk2);
-    throttle_group_unregister_blk(blk3);
+    throttle_group_unregister_tgm(tgm1);
+    throttle_group_unregister_tgm(tgm2);
+    throttle_group_unregister_tgm(tgm3);
 
-    g_assert(blkp1->throttle_state == NULL);
-    g_assert(blkp2->throttle_state == NULL);
-    g_assert(blkp3->throttle_state == NULL);
+    g_assert(tgm1->throttle_state == NULL);
+    g_assert(tgm2->throttle_state == NULL);
+    g_assert(tgm3->throttle_state == NULL);
 }
 
 int main(int argc, char **argv)
@@ -731,6 +739,7 @@ int main(int argc, char **argv)
     qemu_init_main_loop(&error_fatal);
     ctx = qemu_get_aio_context();
     bdrv_init();
+    module_call_init(MODULE_INIT_QOM);
 
     do {} while (g_main_context_iteration(NULL, false));
 
diff --git a/util/throttle.c b/util/throttle.c
index b8c524336c..06bf916adc 100644
--- a/util/throttle.c
+++ b/util/throttle.c
@@ -484,3 +484,154 @@ void throttle_account(ThrottleState *ts, bool is_write, uint64_t size)
     }
 }
 
+/* return a ThrottleConfig based on the options in a ThrottleLimits
+ *
+ * @arg:    the ThrottleLimits object to read from
+ * @cfg:    the ThrottleConfig to edit
+ * @errp:   error object
+ */
+void throttle_limits_to_config(ThrottleLimits *arg, ThrottleConfig *cfg,
+                               Error **errp)
+{
+    if (arg->has_bps_total) {
+        cfg->buckets[THROTTLE_BPS_TOTAL].avg = arg->bps_total;
+    }
+    if (arg->has_bps_read) {
+        cfg->buckets[THROTTLE_BPS_READ].avg  = arg->bps_read;
+    }
+    if (arg->has_bps_write) {
+        cfg->buckets[THROTTLE_BPS_WRITE].avg = arg->bps_write;
+    }
+
+    if (arg->has_iops_total) {
+        cfg->buckets[THROTTLE_OPS_TOTAL].avg = arg->iops_total;
+    }
+    if (arg->has_iops_read) {
+        cfg->buckets[THROTTLE_OPS_READ].avg  = arg->iops_read;
+    }
+    if (arg->has_iops_write) {
+        cfg->buckets[THROTTLE_OPS_WRITE].avg = arg->iops_write;
+    }
+
+    if (arg->has_bps_total_max) {
+        cfg->buckets[THROTTLE_BPS_TOTAL].max = arg->bps_total_max;
+    }
+    if (arg->has_bps_read_max) {
+        cfg->buckets[THROTTLE_BPS_READ].max = arg->bps_read_max;
+    }
+    if (arg->has_bps_write_max) {
+        cfg->buckets[THROTTLE_BPS_WRITE].max = arg->bps_write_max;
+    }
+    if (arg->has_iops_total_max) {
+        cfg->buckets[THROTTLE_OPS_TOTAL].max = arg->iops_total_max;
+    }
+    if (arg->has_iops_read_max) {
+        cfg->buckets[THROTTLE_OPS_READ].max = arg->iops_read_max;
+    }
+    if (arg->has_iops_write_max) {
+        cfg->buckets[THROTTLE_OPS_WRITE].max = arg->iops_write_max;
+    }
+
+    if (arg->has_bps_total_max_length) {
+        if (arg->bps_total_max_length > UINT_MAX) {
+            error_setg(errp, "bps-total-max-length value must be in"
+                             " the range [0, %u]", UINT_MAX);
+            return;
+        }
+        cfg->buckets[THROTTLE_BPS_TOTAL].burst_length = arg->bps_total_max_length;
+    }
+    if (arg->has_bps_read_max_length) {
+        if (arg->bps_read_max_length > UINT_MAX) {
+            error_setg(errp, "bps-read-max-length value must be in"
+                             " the range [0, %u]", UINT_MAX);
+            return;
+        }
+        cfg->buckets[THROTTLE_BPS_READ].burst_length = arg->bps_read_max_length;
+    }
+    if (arg->has_bps_write_max_length) {
+        if (arg->bps_write_max_length > UINT_MAX) {
+            error_setg(errp, "bps-write-max-length value must be in"
+                             " the range [0, %u]", UINT_MAX);
+            return;
+        }
+        cfg->buckets[THROTTLE_BPS_WRITE].burst_length = arg->bps_write_max_length;
+    }
+    if (arg->has_iops_total_max_length) {
+        if (arg->iops_total_max_length > UINT_MAX) {
+            error_setg(errp, "iops-total-max-length value must be in"
+                             " the range [0, %u]", UINT_MAX);
+            return;
+        }
+        cfg->buckets[THROTTLE_OPS_TOTAL].burst_length = arg->iops_total_max_length;
+    }
+    if (arg->has_iops_read_max_length) {
+        if (arg->iops_read_max_length > UINT_MAX) {
+            error_setg(errp, "iops-read-max-length value must be in"
+                             " the range [0, %u]", UINT_MAX);
+            return;
+        }
+        cfg->buckets[THROTTLE_OPS_READ].burst_length = arg->iops_read_max_length;
+    }
+    if (arg->has_iops_write_max_length) {
+        if (arg->iops_write_max_length > UINT_MAX) {
+            error_setg(errp, "iops-write-max-length value must be in"
+                             " the range [0, %u]", UINT_MAX);
+            return;
+        }
+        cfg->buckets[THROTTLE_OPS_WRITE].burst_length = arg->iops_write_max_length;
+    }
+
+    if (arg->has_iops_size) {
+        cfg->op_size = arg->iops_size;
+    }
+
+    throttle_is_valid(cfg, errp);
+}
+
+/* write the options of a ThrottleConfig to a ThrottleLimits
+ *
+ * @cfg:    the ThrottleConfig to read from
+ * @var:    the ThrottleLimits to write to
+ */
+void throttle_config_to_limits(ThrottleConfig *cfg, ThrottleLimits *var)
+{
+    var->bps_total               = cfg->buckets[THROTTLE_BPS_TOTAL].avg;
+    var->bps_read                = cfg->buckets[THROTTLE_BPS_READ].avg;
+    var->bps_write               = cfg->buckets[THROTTLE_BPS_WRITE].avg;
+    var->iops_total              = cfg->buckets[THROTTLE_OPS_TOTAL].avg;
+    var->iops_read               = cfg->buckets[THROTTLE_OPS_READ].avg;
+    var->iops_write              = cfg->buckets[THROTTLE_OPS_WRITE].avg;
+    var->bps_total_max           = cfg->buckets[THROTTLE_BPS_TOTAL].max;
+    var->bps_read_max            = cfg->buckets[THROTTLE_BPS_READ].max;
+    var->bps_write_max           = cfg->buckets[THROTTLE_BPS_WRITE].max;
+    var->iops_total_max          = cfg->buckets[THROTTLE_OPS_TOTAL].max;
+    var->iops_read_max           = cfg->buckets[THROTTLE_OPS_READ].max;
+    var->iops_write_max          = cfg->buckets[THROTTLE_OPS_WRITE].max;
+    var->bps_total_max_length    = cfg->buckets[THROTTLE_BPS_TOTAL].burst_length;
+    var->bps_read_max_length     = cfg->buckets[THROTTLE_BPS_READ].burst_length;
+    var->bps_write_max_length    = cfg->buckets[THROTTLE_BPS_WRITE].burst_length;
+    var->iops_total_max_length   = cfg->buckets[THROTTLE_OPS_TOTAL].burst_length;
+    var->iops_read_max_length    = cfg->buckets[THROTTLE_OPS_READ].burst_length;
+    var->iops_write_max_length   = cfg->buckets[THROTTLE_OPS_WRITE].burst_length;
+    var->iops_size               = cfg->op_size;
+
+    var->has_bps_total = true;
+    var->has_bps_read = true;
+    var->has_bps_write = true;
+    var->has_iops_total = true;
+    var->has_iops_read = true;
+    var->has_iops_write = true;
+    var->has_bps_total_max = true;
+    var->has_bps_read_max = true;
+    var->has_bps_write_max = true;
+    var->has_iops_total_max = true;
+    var->has_iops_read_max = true;
+    var->has_iops_write_max = true;
+    var->has_bps_read_max_length = true;
+    var->has_bps_total_max_length = true;
+    var->has_bps_write_max_length = true;
+    var->has_iops_total_max_length = true;
+    var->has_iops_read_max_length = true;
+    var->has_iops_write_max_length = true;
+    var->has_iops_size = true;
+}