Merge remote-tracking branch 'kwolf/for-anthony' into staging

* kwolf/for-anthony: (46 commits)
  qed: remove incoming live migration blocker
  qed: honor BDRV_O_INCOMING for incoming live migration
  migration: clear BDRV_O_INCOMING flags on end of incoming live migration
  qed: add bdrv_invalidate_cache to be called after incoming live migration
  blockdev: open images with BDRV_O_INCOMING on incoming live migration
  block: add a function to clear incoming live migration flags
  block: Add new BDRV_O_INCOMING flag to notice incoming live migration
  block stream: close unused files and update ->backing_hd
  qemu-iotests: Fix call syntax for qemu-io
  qemu-iotests: Fix call syntax for qemu-img
  qemu-iotests: Test unknown qcow2 header extensions
  qemu-iotests: qcow2.py
  sheepdog: fix send req helpers
  sheepdog: implement SD_OP_FLUSH_VDI operation
  block: bdrv_append() fixes
  qed: track dirty flag status
  qemu-img: add dirty flag status
  qed: image fragmentation statistics
  qemu-img: add image fragmentation statistics
  block: document job API
  ...

14 files changed, 312 insertions, 408 deletions

diff --git a/block/blkdebug.c b/block/blkdebug.c
index a251802ad4..e56e37da51 100644
--- a/block/blkdebug.c
+++ b/block/blkdebug.c
@@ -397,12 +397,6 @@ static void blkdebug_close(BlockDriverState *bs)
     }
 }
 
-static BlockDriverAIOCB *blkdebug_aio_flush(BlockDriverState *bs,
-    BlockDriverCompletionFunc *cb, void *opaque)
-{
-    return bdrv_aio_flush(bs->file, cb, opaque);
-}
-
 static void process_rule(BlockDriverState *bs, struct BlkdebugRule *rule,
     BlkdebugVars *old_vars)
 {
@@ -452,7 +446,6 @@ static BlockDriver bdrv_blkdebug = {
 
     .bdrv_aio_readv     = blkdebug_aio_readv,
     .bdrv_aio_writev    = blkdebug_aio_writev,
-    .bdrv_aio_flush     = blkdebug_aio_flush,
 
     .bdrv_debug_event   = blkdebug_debug_event,
 };
diff --git a/block/cow.c b/block/cow.c
index bb5927c6aa..8d3c9f873c 100644
--- a/block/cow.c
+++ b/block/cow.c
@@ -318,11 +318,6 @@ exit:
     return ret;
 }
 
-static coroutine_fn int cow_co_flush(BlockDriverState *bs)
-{
-    return bdrv_co_flush(bs->file);
-}
-
 static QEMUOptionParameter cow_create_options[] = {
     {
         .name = BLOCK_OPT_SIZE,
@@ -348,7 +343,6 @@ static BlockDriver bdrv_cow = {
 
     .bdrv_read              = cow_co_read,
     .bdrv_write             = cow_co_write,
-    .bdrv_co_flush_to_disk  = cow_co_flush,
     .bdrv_co_is_allocated   = cow_co_is_allocated,
 
     .create_options = cow_create_options,
diff --git a/block/qcow.c b/block/qcow.c
index b1cfe1f696..35dff497ae 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -835,11 +835,6 @@ fail:
     return ret;
 }
 
-static coroutine_fn int qcow_co_flush(BlockDriverState *bs)
-{
-    return bdrv_co_flush(bs->file);
-}
-
 static int qcow_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
 {
     BDRVQcowState *s = bs->opaque;
@@ -877,7 +872,6 @@ static BlockDriver bdrv_qcow = {
 
     .bdrv_co_readv          = qcow_co_readv,
     .bdrv_co_writev         = qcow_co_writev,
-    .bdrv_co_flush_to_disk  = qcow_co_flush,
     .bdrv_co_is_allocated   = qcow_co_is_allocated,
 
     .bdrv_set_key           = qcow_set_key,
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index e0fb90792f..cbd224dc46 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -466,7 +466,6 @@ out:
  */
 static int get_cluster_table(BlockDriverState *bs, uint64_t offset,
                              uint64_t **new_l2_table,
-                             uint64_t *new_l2_offset,
                              int *new_l2_index)
 {
     BDRVQcowState *s = bs->opaque;
@@ -514,7 +513,6 @@ static int get_cluster_table(BlockDriverState *bs, uint64_t offset,
     l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1);
 
     *new_l2_table = l2_table;
-    *new_l2_offset = l2_offset;
     *new_l2_index = l2_index;
 
     return 0;
@@ -539,11 +537,11 @@ uint64_t qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
 {
     BDRVQcowState *s = bs->opaque;
     int l2_index, ret;
-    uint64_t l2_offset, *l2_table;
+    uint64_t *l2_table;
     int64_t cluster_offset;
     int nb_csectors;
 
-    ret = get_cluster_table(bs, offset, &l2_table, &l2_offset, &l2_index);
+    ret = get_cluster_table(bs, offset, &l2_table, &l2_index);
     if (ret < 0) {
         return 0;
     }
@@ -588,7 +586,7 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m)
 {
     BDRVQcowState *s = bs->opaque;
     int i, j = 0, l2_index, ret;
-    uint64_t *old_cluster, start_sect, l2_offset, *l2_table;
+    uint64_t *old_cluster, start_sect, *l2_table;
     uint64_t cluster_offset = m->alloc_offset;
     bool cow = false;
 
@@ -633,7 +631,7 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m)
     }
 
     qcow2_cache_set_dependency(bs, s->l2_table_cache, s->refcount_block_cache);
-    ret = get_cluster_table(bs, m->offset, &l2_table, &l2_offset, &l2_index);
+    ret = get_cluster_table(bs, m->offset, &l2_table, &l2_index);
     if (ret < 0) {
         goto err;
     }
@@ -817,7 +815,7 @@ int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
 {
     BDRVQcowState *s = bs->opaque;
     int l2_index, ret, sectors;
-    uint64_t l2_offset, *l2_table;
+    uint64_t *l2_table;
     unsigned int nb_clusters, keep_clusters;
     uint64_t cluster_offset;
 
@@ -825,7 +823,7 @@ int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
                                       n_start, n_end);
 
     /* Find L2 entry for the first involved cluster */
-    ret = get_cluster_table(bs, offset, &l2_table, &l2_offset, &l2_index);
+    ret = get_cluster_table(bs, offset, &l2_table, &l2_index);
     if (ret < 0) {
         return ret;
     }
@@ -1000,12 +998,12 @@ static int discard_single_l2(BlockDriverState *bs, uint64_t offset,
     unsigned int nb_clusters)
 {
     BDRVQcowState *s = bs->opaque;
-    uint64_t l2_offset, *l2_table;
+    uint64_t *l2_table;
     int l2_index;
     int ret;
     int i;
 
-    ret = get_cluster_table(bs, offset, &l2_table, &l2_offset, &l2_index);
+    ret = get_cluster_table(bs, offset, &l2_table, &l2_index);
     if (ret < 0) {
         return ret;
     }
diff --git a/block/qcow2.c b/block/qcow2.c
index 7aece65406..70d3141dd1 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1253,11 +1253,6 @@ static coroutine_fn int qcow2_co_flush_to_os(BlockDriverState *bs)
     return 0;
 }
 
-static coroutine_fn int qcow2_co_flush_to_disk(BlockDriverState *bs)
-{
-    return bdrv_co_flush(bs->file);
-}
-
 static int64_t qcow2_vm_state_offset(BDRVQcowState *s)
 {
 	return (int64_t)s->l1_vm_state_index << (s->cluster_bits + s->l2_bits);
@@ -1377,7 +1372,6 @@ static BlockDriver bdrv_qcow2 = {
     .bdrv_co_readv          = qcow2_co_readv,
     .bdrv_co_writev         = qcow2_co_writev,
     .bdrv_co_flush_to_os    = qcow2_co_flush_to_os,
-    .bdrv_co_flush_to_disk  = qcow2_co_flush_to_disk,
 
     .bdrv_co_discard        = qcow2_co_discard,
     .bdrv_truncate          = qcow2_truncate,
diff --git a/block/qed-check.c b/block/qed-check.c
index e4a49ce72c..94327ff5b3 100644
--- a/block/qed-check.c
+++ b/block/qed-check.c
@@ -68,6 +68,7 @@ static unsigned int qed_check_l2_table(QEDCheck *check, QEDTable *table)
 {
     BDRVQEDState *s = check->s;
     unsigned int i, num_invalid = 0;
+    uint64_t last_offset = 0;
 
     for (i = 0; i < s->table_nelems; i++) {
         uint64_t offset = table->offsets[i];
@@ -76,6 +77,11 @@ static unsigned int qed_check_l2_table(QEDCheck *check, QEDTable *table)
             qed_offset_is_zero_cluster(offset)) {
             continue;
         }
+        check->result->bfi.allocated_clusters++;
+        if (last_offset && (last_offset + s->header.cluster_size != offset)) {
+            check->result->bfi.fragmented_clusters++;
+        }
+        last_offset = offset;
 
         /* Detect invalid cluster offset */
         if (!qed_check_cluster_offset(s, offset)) {
@@ -200,6 +206,9 @@ int qed_check(BDRVQEDState *s, BdrvCheckResult *result, bool fix)
     check.used_clusters = g_malloc0(((check.nclusters + 31) / 32) *
                                        sizeof(check.used_clusters[0]));
 
+    check.result->bfi.total_clusters =
+        (s->header.image_size + s->header.cluster_size - 1) /
+            s->header.cluster_size;
     ret = qed_check_l1_table(&check, s->l1_table);
     if (ret == 0) {
         /* Only check for leaks if entire image was scanned successfully */
diff --git a/block/qed.c b/block/qed.c
index a041d31e66..366cde7ad8 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -450,7 +450,7 @@ static int bdrv_qed_open(BlockDriverState *bs, int flags)
      * feature is no longer valid.
      */
     if ((s->header.autoclear_features & ~QED_AUTOCLEAR_FEATURE_MASK) != 0 &&
-        !bdrv_is_read_only(bs->file)) {
+        !bdrv_is_read_only(bs->file) && !(flags & BDRV_O_INCOMING)) {
         s->header.autoclear_features &= QED_AUTOCLEAR_FEATURE_MASK;
 
         ret = qed_write_header_sync(s);
@@ -477,7 +477,8 @@ static int bdrv_qed_open(BlockDriverState *bs, int flags)
          * potentially inconsistent images to be opened read-only.  This can
          * aid data recovery from an otherwise inconsistent image.
          */
-        if (!bdrv_is_read_only(bs->file)) {
+        if (!bdrv_is_read_only(bs->file) &&
+            !(flags & BDRV_O_INCOMING)) {
             BdrvCheckResult result = {0};
 
             ret = qed_check(s, &result, true);
@@ -497,12 +498,6 @@ static int bdrv_qed_open(BlockDriverState *bs, int flags)
     s->need_check_timer = qemu_new_timer_ns(vm_clock,
                                             qed_need_check_timer_cb, s);
 
-    error_set(&s->migration_blocker,
-              QERR_BLOCK_FORMAT_FEATURE_NOT_SUPPORTED,
-              "qed", bs->device_name, "live migration");
-    migrate_add_blocker(s->migration_blocker);
-
-
 out:
     if (ret) {
         qed_free_l2_cache(&s->l2_cache);
@@ -515,9 +510,6 @@ static void bdrv_qed_close(BlockDriverState *bs)
 {
     BDRVQEDState *s = bs->opaque;
 
-    migrate_del_blocker(s->migration_blocker);
-    error_free(s->migration_blocker);
-
     qed_cancel_need_check_timer(s);
     qemu_free_timer(s->need_check_timer);
 
@@ -1350,13 +1342,6 @@ static BlockDriverAIOCB *bdrv_qed_aio_writev(BlockDriverState *bs,
                          opaque, QED_AIOCB_WRITE);
 }
 
-static BlockDriverAIOCB *bdrv_qed_aio_flush(BlockDriverState *bs,
-                                            BlockDriverCompletionFunc *cb,
-                                            void *opaque)
-{
-    return bdrv_aio_flush(bs->file, cb, opaque);
-}
-
 typedef struct {
     Coroutine *co;
     int ret;
@@ -1441,6 +1426,7 @@ static int bdrv_qed_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
 
     memset(bdi, 0, sizeof(*bdi));
     bdi->cluster_size = s->header.cluster_size;
+    bdi->is_dirty = s->header.features & QED_F_NEED_CHECK;
     return 0;
 }
 
@@ -1516,6 +1502,15 @@ static int bdrv_qed_change_backing_file(BlockDriverState *bs,
     return ret;
 }
 
+static void bdrv_qed_invalidate_cache(BlockDriverState *bs)
+{
+    BDRVQEDState *s = bs->opaque;
+
+    bdrv_qed_close(bs);
+    memset(s, 0, sizeof(BDRVQEDState));
+    bdrv_qed_open(bs, bs->open_flags);
+}
+
 static int bdrv_qed_check(BlockDriverState *bs, BdrvCheckResult *result)
 {
     BDRVQEDState *s = bs->opaque;
@@ -1562,12 +1557,12 @@ static BlockDriver bdrv_qed = {
     .bdrv_make_empty          = bdrv_qed_make_empty,
     .bdrv_aio_readv           = bdrv_qed_aio_readv,
     .bdrv_aio_writev          = bdrv_qed_aio_writev,
-    .bdrv_aio_flush           = bdrv_qed_aio_flush,
     .bdrv_co_write_zeroes     = bdrv_qed_co_write_zeroes,
     .bdrv_truncate            = bdrv_qed_truncate,
     .bdrv_getlength           = bdrv_qed_getlength,
     .bdrv_get_info            = bdrv_qed_get_info,
     .bdrv_change_backing_file = bdrv_qed_change_backing_file,
+    .bdrv_invalidate_cache    = bdrv_qed_invalidate_cache,
     .bdrv_check               = bdrv_qed_check,
 };
 
diff --git a/block/qed.h b/block/qed.h
index 62624a1f34..c716772ad7 100644
--- a/block/qed.h
+++ b/block/qed.h
@@ -169,8 +169,6 @@ typedef struct {
 
     /* Periodic flush and clear need check flag */
     QEMUTimer *need_check_timer;
-
-    Error *migration_blocker;
 } BDRVQEDState;
 
 enum {
diff --git a/block/raw.c b/block/raw.c
index 1cdac0ccdc..7086e314a6 100644
--- a/block/raw.c
+++ b/block/raw.c
@@ -25,11 +25,6 @@ static void raw_close(BlockDriverState *bs)
 {
 }
 
-static int coroutine_fn raw_co_flush(BlockDriverState *bs)
-{
-    return bdrv_co_flush(bs->file);
-}
-
 static int64_t raw_getlength(BlockDriverState *bs)
 {
     return bdrv_getlength(bs->file);
@@ -113,7 +108,6 @@ static BlockDriver bdrv_raw = {
 
     .bdrv_co_readv          = raw_co_readv,
     .bdrv_co_writev         = raw_co_writev,
-    .bdrv_co_flush_to_disk  = raw_co_flush,
     .bdrv_co_discard        = raw_co_discard,
 
     .bdrv_probe         = raw_probe,
diff --git a/block/sheepdog.c b/block/sheepdog.c
index 00276f6f46..3eaf625e98 100644
--- a/block/sheepdog.c
+++ b/block/sheepdog.c
@@ -32,9 +32,11 @@
 #define SD_OP_RELEASE_VDI    0x13
 #define SD_OP_GET_VDI_INFO   0x14
 #define SD_OP_READ_VDIS      0x15
+#define SD_OP_FLUSH_VDI      0x16
 
 #define SD_FLAG_CMD_WRITE    0x01
 #define SD_FLAG_CMD_COW      0x02
+#define SD_FLAG_CMD_CACHE    0x04
 
 #define SD_RES_SUCCESS       0x00 /* Success */
 #define SD_RES_UNKNOWN       0x01 /* Unknown error */
@@ -293,10 +295,12 @@ typedef struct BDRVSheepdogState {
 
     char name[SD_MAX_VDI_LEN];
     int is_snapshot;
+    uint8_t cache_enabled;
 
     char *addr;
     char *port;
     int fd;
+    int flush_fd;
 
     CoMutex lock;
     Coroutine *co_send;
@@ -506,6 +510,7 @@ static int send_req(int sockfd, SheepdogReq *hdr, void *data,
     ret = qemu_send_full(sockfd, hdr, sizeof(*hdr), 0);
     if (ret < sizeof(*hdr)) {
         error_report("failed to send a req, %s", strerror(errno));
+        return ret;
     }
 
     ret = qemu_send_full(sockfd, data, *wlen, 0);
@@ -516,6 +521,24 @@ static int send_req(int sockfd, SheepdogReq *hdr, void *data,
     return ret;
 }
 
+static int send_co_req(int sockfd, SheepdogReq *hdr, void *data,
+                       unsigned int *wlen)
+{
+    int ret;
+
+    ret = qemu_co_send(sockfd, hdr, sizeof(*hdr));
+    if (ret < sizeof(*hdr)) {
+        error_report("failed to send a req, %s", strerror(errno));
+        return ret;
+    }
+
+    ret = qemu_co_send(sockfd, data, *wlen);
+    if (ret < *wlen) {
+        error_report("failed to send a req, %s", strerror(errno));
+    }
+
+    return ret;
+}
 static int do_req(int sockfd, SheepdogReq *hdr, void *data,
                   unsigned int *wlen, unsigned int *rlen)
 {
@@ -550,6 +573,40 @@ out:
     return ret;
 }
 
+static int do_co_req(int sockfd, SheepdogReq *hdr, void *data,
+                     unsigned int *wlen, unsigned int *rlen)
+{
+    int ret;
+
+    socket_set_block(sockfd);
+    ret = send_co_req(sockfd, hdr, data, wlen);
+    if (ret < 0) {
+        goto out;
+    }
+
+    ret = qemu_co_recv(sockfd, hdr, sizeof(*hdr));
+    if (ret < sizeof(*hdr)) {
+        error_report("failed to get a rsp, %s", strerror(errno));
+        goto out;
+    }
+
+    if (*rlen > hdr->data_length) {
+        *rlen = hdr->data_length;
+    }
+
+    if (*rlen) {
+        ret = qemu_co_recv(sockfd, data, *rlen);
+        if (ret < *rlen) {
+            error_report("failed to get the data, %s", strerror(errno));
+            goto out;
+        }
+    }
+    ret = 0;
+out:
+    socket_set_nonblock(sockfd);
+    return ret;
+}
+
 static int coroutine_fn add_aio_request(BDRVSheepdogState *s, AIOReq *aio_req,
                            struct iovec *iov, int niov, int create,
                            enum AIOCBState aiocb_type);
@@ -900,6 +957,10 @@ static int coroutine_fn add_aio_request(BDRVSheepdogState *s, AIOReq *aio_req,
         hdr.flags = SD_FLAG_CMD_WRITE | flags;
     }
 
+    if (s->cache_enabled) {
+        hdr.flags |= SD_FLAG_CMD_CACHE;
+    }
+
     hdr.oid = oid;
     hdr.cow_oid = old_oid;
     hdr.copies = s->inode.nr_copies;
@@ -942,7 +1003,7 @@ static int coroutine_fn add_aio_request(BDRVSheepdogState *s, AIOReq *aio_req,
 
 static int read_write_object(int fd, char *buf, uint64_t oid, int copies,
                              unsigned int datalen, uint64_t offset,
-                             int write, int create)
+                             int write, int create, uint8_t cache)
 {
     SheepdogObjReq hdr;
     SheepdogObjRsp *rsp = (SheepdogObjRsp *)&hdr;
@@ -965,6 +1026,11 @@ static int read_write_object(int fd, char *buf, uint64_t oid, int copies,
         rlen = datalen;
         hdr.opcode = SD_OP_READ_OBJ;
     }
+
+    if (cache) {
+        hdr.flags |= SD_FLAG_CMD_CACHE;
+    }
+
     hdr.oid = oid;
     hdr.data_length = datalen;
     hdr.offset = offset;
@@ -986,15 +1052,18 @@ static int read_write_object(int fd, char *buf, uint64_t oid, int copies,
 }
 
 static int read_object(int fd, char *buf, uint64_t oid, int copies,
-                       unsigned int datalen, uint64_t offset)
+                       unsigned int datalen, uint64_t offset, uint8_t cache)
 {
-    return read_write_object(fd, buf, oid, copies, datalen, offset, 0, 0);
+    return read_write_object(fd, buf, oid, copies, datalen, offset, 0, 0,
+                             cache);
 }
 
 static int write_object(int fd, char *buf, uint64_t oid, int copies,
-                        unsigned int datalen, uint64_t offset, int create)
+                        unsigned int datalen, uint64_t offset, int create,
+                        uint8_t cache)
 {
-    return read_write_object(fd, buf, oid, copies, datalen, offset, 1, create);
+    return read_write_object(fd, buf, oid, copies, datalen, offset, 1, create,
+                             cache);
 }
 
 static int sd_open(BlockDriverState *bs, const char *filename, int flags)
@@ -1026,6 +1095,15 @@ static int sd_open(BlockDriverState *bs, const char *filename, int flags)
         goto out;
     }
 
+    if (flags & BDRV_O_CACHE_WB) {
+        s->cache_enabled = 1;
+        s->flush_fd = connect_to_sdog(s->addr, s->port);
+        if (s->flush_fd < 0) {
+            error_report("failed to connect");
+            goto out;
+        }
+    }
+
     if (snapid) {
         dprintf("%" PRIx32 " snapshot inode was open.\n", vid);
         s->is_snapshot = 1;
@@ -1038,7 +1116,8 @@ static int sd_open(BlockDriverState *bs, const char *filename, int flags)
     }
 
     buf = g_malloc(SD_INODE_SIZE);
-    ret = read_object(fd, buf, vid_to_vdi_oid(vid), 0, SD_INODE_SIZE, 0);
+    ret = read_object(fd, buf, vid_to_vdi_oid(vid), 0, SD_INODE_SIZE, 0,
+                      s->cache_enabled);
 
     closesocket(fd);
 
@@ -1272,6 +1351,9 @@ static void sd_close(BlockDriverState *bs)
 
     qemu_aio_set_fd_handler(s->fd, NULL, NULL, NULL, NULL, NULL);
     closesocket(s->fd);
+    if (s->cache_enabled) {
+        closesocket(s->flush_fd);
+    }
     g_free(s->addr);
 }
 
@@ -1305,7 +1387,7 @@ static int sd_truncate(BlockDriverState *bs, int64_t offset)
     datalen = SD_INODE_SIZE - sizeof(s->inode.data_vdi_id);
     s->inode.vdi_size = offset;
     ret = write_object(fd, (char *)&s->inode, vid_to_vdi_oid(s->inode.vdi_id),
-                       s->inode.nr_copies, datalen, 0, 0);
+                       s->inode.nr_copies, datalen, 0, 0, s->cache_enabled);
     close(fd);
 
     if (ret < 0) {
@@ -1387,7 +1469,7 @@ static int sd_create_branch(BDRVSheepdogState *s)
     }
 
     ret = read_object(fd, buf, vid_to_vdi_oid(vid), s->inode.nr_copies,
-                      SD_INODE_SIZE, 0);
+                      SD_INODE_SIZE, 0, s->cache_enabled);
 
     closesocket(fd);
 
@@ -1575,6 +1657,36 @@ static coroutine_fn int sd_co_readv(BlockDriverState *bs, int64_t sector_num,
     return acb->ret;
 }
 
+static int coroutine_fn sd_co_flush_to_disk(BlockDriverState *bs)
+{
+    BDRVSheepdogState *s = bs->opaque;
+    SheepdogObjReq hdr = { 0 };
+    SheepdogObjRsp *rsp = (SheepdogObjRsp *)&hdr;
+    SheepdogInode *inode = &s->inode;
+    int ret;
+    unsigned int wlen = 0, rlen = 0;
+
+    if (!s->cache_enabled) {
+        return 0;
+    }
+
+    hdr.opcode = SD_OP_FLUSH_VDI;
+    hdr.oid = vid_to_vdi_oid(inode->vdi_id);
+
+    ret = do_co_req(s->flush_fd, (SheepdogReq *)&hdr, NULL, &wlen, &rlen);
+    if (ret) {
+        error_report("failed to send a request to the sheep");
+        return ret;
+    }
+
+    if (rsp->result != SD_RES_SUCCESS) {
+        error_report("%s", sd_strerror(rsp->result));
+        return -EIO;
+    }
+
+    return 0;
+}
+
 static int sd_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
 {
     BDRVSheepdogState *s = bs->opaque;
@@ -1610,7 +1722,7 @@ static int sd_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
     }
 
     ret = write_object(fd, (char *)&s->inode, vid_to_vdi_oid(s->inode.vdi_id),
-                       s->inode.nr_copies, datalen, 0, 0);
+                       s->inode.nr_copies, datalen, 0, 0, s->cache_enabled);
     if (ret < 0) {
         error_report("failed to write snapshot's inode.");
         ret = -EIO;
@@ -1629,7 +1741,7 @@ static int sd_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
     inode = (SheepdogInode *)g_malloc(datalen);
 
     ret = read_object(fd, (char *)inode, vid_to_vdi_oid(new_vid),
-                      s->inode.nr_copies, datalen, 0);
+                      s->inode.nr_copies, datalen, 0, s->cache_enabled);
 
     if (ret < 0) {
         error_report("failed to read new inode info. %s", strerror(errno));
@@ -1684,7 +1796,7 @@ static int sd_snapshot_goto(BlockDriverState *bs, const char *snapshot_id)
 
     buf = g_malloc(SD_INODE_SIZE);
     ret = read_object(fd, buf, vid_to_vdi_oid(vid), s->inode.nr_copies,
-                      SD_INODE_SIZE, 0);
+                      SD_INODE_SIZE, 0, s->cache_enabled);
 
     closesocket(fd);
 
@@ -1779,7 +1891,8 @@ static int sd_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab)
 
         /* we don't need to read entire object */
         ret = read_object(fd, (char *)&inode, vid_to_vdi_oid(vid),
-                          0, SD_INODE_SIZE - sizeof(inode.data_vdi_id), 0);
+                          0, SD_INODE_SIZE - sizeof(inode.data_vdi_id), 0,
+                          s->cache_enabled);
 
         if (ret) {
             continue;
@@ -1835,10 +1948,12 @@ static int do_load_save_vmstate(BDRVSheepdogState *s, uint8_t *data,
         create = (offset == 0);
         if (load) {
             ret = read_object(fd, (char *)data, vmstate_oid,
-                              s->inode.nr_copies, data_len, offset);
+                              s->inode.nr_copies, data_len, offset,
+                              s->cache_enabled);
         } else {
             ret = write_object(fd, (char *)data, vmstate_oid,
-                               s->inode.nr_copies, data_len, offset, create);
+                               s->inode.nr_copies, data_len, offset, create,
+                               s->cache_enabled);
         }
 
         if (ret < 0) {
@@ -1904,6 +2019,7 @@ BlockDriver bdrv_sheepdog = {
 
     .bdrv_co_readv  = sd_co_readv,
     .bdrv_co_writev = sd_co_writev,
+    .bdrv_co_flush_to_disk  = sd_co_flush_to_disk,
 
     .bdrv_snapshot_create   = sd_snapshot_create,
     .bdrv_snapshot_goto     = sd_snapshot_goto,
diff --git a/block/stream.c b/block/stream.c
index d1b3986a8a..0efe1adfd5 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -76,6 +76,39 @@ static int coroutine_fn stream_populate(BlockDriverState *bs,
     return bdrv_co_copy_on_readv(bs, sector_num, nb_sectors, &qiov);
 }
 
+static void close_unused_images(BlockDriverState *top, BlockDriverState *base,
+                                const char *base_id)
+{
+    BlockDriverState *intermediate;
+    intermediate = top->backing_hd;
+
+    while (intermediate) {
+        BlockDriverState *unused;
+
+        /* reached base */
+        if (intermediate == base) {
+            break;
+        }
+
+        unused = intermediate;
+        intermediate = intermediate->backing_hd;
+        unused->backing_hd = NULL;
+        bdrv_delete(unused);
+    }
+    top->backing_hd = base;
+
+    pstrcpy(top->backing_file, sizeof(top->backing_file), "");
+    pstrcpy(top->backing_format, sizeof(top->backing_format), "");
+    if (base_id) {
+        pstrcpy(top->backing_file, sizeof(top->backing_file), base_id);
+        if (base->drv) {
+            pstrcpy(top->backing_format, sizeof(top->backing_format),
+                    base->drv->format_name);
+        }
+    }
+
+}
+
 /*
  * Given an image chain: [BASE] -> [INTER1] -> [INTER2] -> [TOP]
  *
@@ -175,7 +208,7 @@ retry:
             break;
         }
 
-
+        s->common.busy = true;
         if (base) {
             ret = is_allocated_base(bs, base, sector_num,
                                     STREAM_BUFFER_SIZE / BDRV_SECTOR_SIZE, &n);
@@ -189,6 +222,7 @@ retry:
             if (s->common.speed) {
                 uint64_t delay_ns = ratelimit_calculate_delay(&s->limit, n);
                 if (delay_ns > 0) {
+                    s->common.busy = false;
                     co_sleep_ns(rt_clock, delay_ns);
 
                     /* Recheck cancellation and that sectors are unallocated */
@@ -208,6 +242,7 @@ retry:
         /* Note that even when no rate limit is applied we need to yield
          * with no pending I/O here so that qemu_aio_flush() returns.
          */
+        s->common.busy = false;
         co_sleep_ns(rt_clock, 0);
     }
 
@@ -215,12 +250,13 @@ retry:
         bdrv_disable_copy_on_read(bs);
     }
 
-    if (sector_num == end && ret == 0) {
+    if (!block_job_is_cancelled(&s->common) && sector_num == end && ret == 0) {
         const char *base_id = NULL;
         if (base) {
             base_id = s->backing_file_id;
         }
         ret = bdrv_change_backing_file(bs, base_id, NULL);
+        close_unused_images(bs, base, base_id);
     }
 
     qemu_vfree(buf);
@@ -234,7 +270,6 @@ static int stream_set_speed(BlockJob *job, int64_t value)
     if (value < 0) {
         return -EINVAL;
     }
-    job->speed = value;
     ratelimit_set_speed(&s->limit, value / BDRV_SECTOR_SIZE);
     return 0;
 }
diff --git a/block/vdi.c b/block/vdi.c
index 6a0011fbcc..119d3c74da 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -144,29 +144,6 @@ void uuid_unparse(const uuid_t uu, char *out)
 #endif
 
 typedef struct {
-    BlockDriverAIOCB common;
-    int64_t sector_num;
-    QEMUIOVector *qiov;
-    uint8_t *buf;
-    /* Total number of sectors. */
-    int nb_sectors;
-    /* Number of sectors for current AIO. */
-    int n_sectors;
-    /* New allocated block map entry. */
-    uint32_t bmap_first;
-    uint32_t bmap_last;
-    /* Buffer for new allocated block. */
-    void *block_buffer;
-    void *orig_buf;
-    bool is_write;
-    int header_modified;
-    BlockDriverAIOCB *hd_aiocb;
-    struct iovec hd_iov;
-    QEMUIOVector hd_qiov;
-    QEMUBH *bh;
-} VdiAIOCB;
-
-typedef struct {
     char text[0x40];
     uint32_t signature;
     uint32_t version;
@@ -489,332 +466,150 @@ static int coroutine_fn vdi_co_is_allocated(BlockDriverState *bs,
     return VDI_IS_ALLOCATED(bmap_entry);
 }
 
-static void vdi_aio_cancel(BlockDriverAIOCB *blockacb)
-{
-    /* TODO: This code is untested. How can I get it executed? */
-    VdiAIOCB *acb = container_of(blockacb, VdiAIOCB, common);
-    logout("\n");
-    if (acb->hd_aiocb) {
-        bdrv_aio_cancel(acb->hd_aiocb);
-    }
-    qemu_aio_release(acb);
-}
-
-static AIOPool vdi_aio_pool = {
-    .aiocb_size = sizeof(VdiAIOCB),
-    .cancel = vdi_aio_cancel,
-};
-
-static VdiAIOCB *vdi_aio_setup(BlockDriverState *bs, int64_t sector_num,
-        QEMUIOVector *qiov, int nb_sectors,
-        BlockDriverCompletionFunc *cb, void *opaque, int is_write)
-{
-    VdiAIOCB *acb;
-
-    logout("%p, %" PRId64 ", %p, %d, %p, %p, %d\n",
-           bs, sector_num, qiov, nb_sectors, cb, opaque, is_write);
-
-    acb = qemu_aio_get(&vdi_aio_pool, bs, cb, opaque);
-    acb->hd_aiocb = NULL;
-    acb->sector_num = sector_num;
-    acb->qiov = qiov;
-    acb->is_write = is_write;
-
-    if (qiov->niov > 1) {
-        acb->buf = qemu_blockalign(bs, qiov->size);
-        acb->orig_buf = acb->buf;
-        if (is_write) {
-            qemu_iovec_to_buffer(qiov, acb->buf);
-        }
-    } else {
-        acb->buf = (uint8_t *)qiov->iov->iov_base;
-    }
-    acb->nb_sectors = nb_sectors;
-    acb->n_sectors = 0;
-    acb->bmap_first = VDI_UNALLOCATED;
-    acb->bmap_last = VDI_UNALLOCATED;
-    acb->block_buffer = NULL;
-    acb->header_modified = 0;
-    return acb;
-}
-
-static int vdi_schedule_bh(QEMUBHFunc *cb, VdiAIOCB *acb)
-{
-    logout("\n");
-
-    if (acb->bh) {
-        return -EIO;
-    }
-
-    acb->bh = qemu_bh_new(cb, acb);
-    if (!acb->bh) {
-        return -EIO;
-    }
-
-    qemu_bh_schedule(acb->bh);
-
-    return 0;
-}
-
-static void vdi_aio_read_cb(void *opaque, int ret);
-static void vdi_aio_write_cb(void *opaque, int ret);
-
-static void vdi_aio_rw_bh(void *opaque)
+static int vdi_co_read(BlockDriverState *bs,
+        int64_t sector_num, uint8_t *buf, int nb_sectors)
 {
-    VdiAIOCB *acb = opaque;
-    logout("\n");
-    qemu_bh_delete(acb->bh);
-    acb->bh = NULL;
-
-    if (acb->is_write) {
-        vdi_aio_write_cb(opaque, 0);
-    } else {
-        vdi_aio_read_cb(opaque, 0);
-    }
-}
-
-static void vdi_aio_read_cb(void *opaque, int ret)
-{
-    VdiAIOCB *acb = opaque;
-    BlockDriverState *bs = acb->common.bs;
     BDRVVdiState *s = bs->opaque;
     uint32_t bmap_entry;
     uint32_t block_index;
     uint32_t sector_in_block;
     uint32_t n_sectors;
+    int ret = 0;
 
-    logout("%u sectors read\n", acb->n_sectors);
-
-    acb->hd_aiocb = NULL;
-
-    if (ret < 0) {
-        goto done;
-    }
-
-    acb->nb_sectors -= acb->n_sectors;
-
-    if (acb->nb_sectors == 0) {
-        /* request completed */
-        ret = 0;
-        goto done;
-    }
-
-    acb->sector_num += acb->n_sectors;
-    acb->buf += acb->n_sectors * SECTOR_SIZE;
-
-    block_index = acb->sector_num / s->block_sectors;
-    sector_in_block = acb->sector_num % s->block_sectors;
-    n_sectors = s->block_sectors - sector_in_block;
-    if (n_sectors > acb->nb_sectors) {
-        n_sectors = acb->nb_sectors;
-    }
-
-    logout("will read %u sectors starting at sector %" PRIu64 "\n",
-           n_sectors, acb->sector_num);
+    logout("\n");
 
-    /* prepare next AIO request */
-    acb->n_sectors = n_sectors;
-    bmap_entry = le32_to_cpu(s->bmap[block_index]);
-    if (!VDI_IS_ALLOCATED(bmap_entry)) {
-        /* Block not allocated, return zeros, no need to wait. */
-        memset(acb->buf, 0, n_sectors * SECTOR_SIZE);
-        ret = vdi_schedule_bh(vdi_aio_rw_bh, acb);
-        if (ret < 0) {
-            goto done;
+    while (ret >= 0 && nb_sectors > 0) {
+        block_index = sector_num / s->block_sectors;
+        sector_in_block = sector_num % s->block_sectors;
+        n_sectors = s->block_sectors - sector_in_block;
+        if (n_sectors > nb_sectors) {
+            n_sectors = nb_sectors;
         }
-    } else {
-        uint64_t offset = s->header.offset_data / SECTOR_SIZE +
-                          (uint64_t)bmap_entry * s->block_sectors +
-                          sector_in_block;
-        acb->hd_iov.iov_base = (void *)acb->buf;
-        acb->hd_iov.iov_len = n_sectors * SECTOR_SIZE;
-        qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
-        acb->hd_aiocb = bdrv_aio_readv(bs->file, offset, &acb->hd_qiov,
-                                       n_sectors, vdi_aio_read_cb, acb);
-    }
-    return;
-done:
-    if (acb->qiov->niov > 1) {
-        qemu_iovec_from_buffer(acb->qiov, acb->orig_buf, acb->qiov->size);
-        qemu_vfree(acb->orig_buf);
-    }
-    acb->common.cb(acb->common.opaque, ret);
-    qemu_aio_release(acb);
-}
 
-static BlockDriverAIOCB *vdi_aio_readv(BlockDriverState *bs,
-        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
-        BlockDriverCompletionFunc *cb, void *opaque)
-{
-    VdiAIOCB *acb;
-    int ret;
+        logout("will read %u sectors starting at sector %" PRIu64 "\n",
+               n_sectors, sector_num);
 
-    logout("\n");
-    acb = vdi_aio_setup(bs, sector_num, qiov, nb_sectors, cb, opaque, 0);
-    ret = vdi_schedule_bh(vdi_aio_rw_bh, acb);
-    if (ret < 0) {
-        if (acb->qiov->niov > 1) {
-            qemu_vfree(acb->orig_buf);
+        /* prepare next AIO request */
+        bmap_entry = le32_to_cpu(s->bmap[block_index]);
+        if (!VDI_IS_ALLOCATED(bmap_entry)) {
+            /* Block not allocated, return zeros, no need to wait. */
+            memset(buf, 0, n_sectors * SECTOR_SIZE);
+            ret = 0;
+        } else {
+            uint64_t offset = s->header.offset_data / SECTOR_SIZE +
+                              (uint64_t)bmap_entry * s->block_sectors +
+                              sector_in_block;
+            ret = bdrv_read(bs->file, offset, buf, n_sectors);
         }
-        qemu_aio_release(acb);
-        return NULL;
+        logout("%u sectors read\n", n_sectors);
+
+        nb_sectors -= n_sectors;
+        sector_num += n_sectors;
+        buf += n_sectors * SECTOR_SIZE;
     }
 
-    return &acb->common;
+    return ret;
 }
 
-static void vdi_aio_write_cb(void *opaque, int ret)
+static int vdi_co_write(BlockDriverState *bs,
+        int64_t sector_num, const uint8_t *buf, int nb_sectors)
 {
-    VdiAIOCB *acb = opaque;
-    BlockDriverState *bs = acb->common.bs;
     BDRVVdiState *s = bs->opaque;
     uint32_t bmap_entry;
     uint32_t block_index;
     uint32_t sector_in_block;
     uint32_t n_sectors;
+    uint32_t bmap_first = VDI_UNALLOCATED;
+    uint32_t bmap_last = VDI_UNALLOCATED;
+    uint8_t *block = NULL;
+    int ret = 0;
 
-    acb->hd_aiocb = NULL;
+    logout("\n");
 
-    if (ret < 0) {
-        goto done;
-    }
+    while (ret >= 0 && nb_sectors > 0) {
+        block_index = sector_num / s->block_sectors;
+        sector_in_block = sector_num % s->block_sectors;
+        n_sectors = s->block_sectors - sector_in_block;
+        if (n_sectors > nb_sectors) {
+            n_sectors = nb_sectors;
+        }
+
+        logout("will write %u sectors starting at sector %" PRIu64 "\n",
+               n_sectors, sector_num);
 
-    acb->nb_sectors -= acb->n_sectors;
-    acb->sector_num += acb->n_sectors;
-    acb->buf += acb->n_sectors * SECTOR_SIZE;
-
-    if (acb->nb_sectors == 0) {
-        logout("finished data write\n");
-        acb->n_sectors = 0;
-        if (acb->header_modified) {
-            VdiHeader *header = acb->block_buffer;
-            logout("now writing modified header\n");
-            assert(VDI_IS_ALLOCATED(acb->bmap_first));
-            *header = s->header;
-            vdi_header_to_le(header);
-            acb->header_modified = 0;
-            acb->hd_iov.iov_base = acb->block_buffer;
-            acb->hd_iov.iov_len = SECTOR_SIZE;
-            qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
-            acb->hd_aiocb = bdrv_aio_writev(bs->file, 0, &acb->hd_qiov, 1,
-                                            vdi_aio_write_cb, acb);
-            return;
-        } else if (VDI_IS_ALLOCATED(acb->bmap_first)) {
-            /* One or more new blocks were allocated. */
+        /* prepare next AIO request */
+        bmap_entry = le32_to_cpu(s->bmap[block_index]);
+        if (!VDI_IS_ALLOCATED(bmap_entry)) {
+            /* Allocate new block and write to it. */
             uint64_t offset;
-            uint32_t bmap_first;
-            uint32_t bmap_last;
-            g_free(acb->block_buffer);
-            acb->block_buffer = NULL;
-            bmap_first = acb->bmap_first;
-            bmap_last = acb->bmap_last;
-            logout("now writing modified block map entry %u...%u\n",
-                   bmap_first, bmap_last);
-            /* Write modified sectors from block map. */
-            bmap_first /= (SECTOR_SIZE / sizeof(uint32_t));
-            bmap_last /= (SECTOR_SIZE / sizeof(uint32_t));
-            n_sectors = bmap_last - bmap_first + 1;
-            offset = s->bmap_sector + bmap_first;
-            acb->bmap_first = VDI_UNALLOCATED;
-            acb->hd_iov.iov_base = (void *)((uint8_t *)&s->bmap[0] +
-                                            bmap_first * SECTOR_SIZE);
-            acb->hd_iov.iov_len = n_sectors * SECTOR_SIZE;
-            qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
-            logout("will write %u block map sectors starting from entry %u\n",
-                   n_sectors, bmap_first);
-            acb->hd_aiocb = bdrv_aio_writev(bs->file, offset, &acb->hd_qiov,
-                                            n_sectors, vdi_aio_write_cb, acb);
-            return;
+            bmap_entry = s->header.blocks_allocated;
+            s->bmap[block_index] = cpu_to_le32(bmap_entry);
+            s->header.blocks_allocated++;
+            offset = s->header.offset_data / SECTOR_SIZE +
+                     (uint64_t)bmap_entry * s->block_sectors;
+            if (block == NULL) {
+                block = g_malloc(s->block_size);
+                bmap_first = block_index;
+            }
+            bmap_last = block_index;
+            /* Copy data to be written to new block and zero unused parts. */
+            memset(block, 0, sector_in_block * SECTOR_SIZE);
+            memcpy(block + sector_in_block * SECTOR_SIZE,
+                   buf, n_sectors * SECTOR_SIZE);
+            memset(block + (sector_in_block + n_sectors) * SECTOR_SIZE, 0,
+                   (s->block_sectors - n_sectors - sector_in_block) * SECTOR_SIZE);
+            ret = bdrv_write(bs->file, offset, block, s->block_sectors);
+        } else {
+            uint64_t offset = s->header.offset_data / SECTOR_SIZE +
+                              (uint64_t)bmap_entry * s->block_sectors +
+                              sector_in_block;
+            ret = bdrv_write(bs->file, offset, buf, n_sectors);
         }
-        ret = 0;
-        goto done;
-    }
 
-    logout("%u sectors written\n", acb->n_sectors);
+        nb_sectors -= n_sectors;
+        sector_num += n_sectors;
+        buf += n_sectors * SECTOR_SIZE;
 
-    block_index = acb->sector_num / s->block_sectors;
-    sector_in_block = acb->sector_num % s->block_sectors;
-    n_sectors = s->block_sectors - sector_in_block;
-    if (n_sectors > acb->nb_sectors) {
-        n_sectors = acb->nb_sectors;
+        logout("%u sectors written\n", n_sectors);
     }
 
-    logout("will write %u sectors starting at sector %" PRIu64 "\n",
-           n_sectors, acb->sector_num);
-
-    /* prepare next AIO request */
-    acb->n_sectors = n_sectors;
-    bmap_entry = le32_to_cpu(s->bmap[block_index]);
-    if (!VDI_IS_ALLOCATED(bmap_entry)) {
-        /* Allocate new block and write to it. */
-        uint64_t offset;
-        uint8_t *block;
-        bmap_entry = s->header.blocks_allocated;
-        s->bmap[block_index] = cpu_to_le32(bmap_entry);
-        s->header.blocks_allocated++;
-        offset = s->header.offset_data / SECTOR_SIZE +
-                 (uint64_t)bmap_entry * s->block_sectors;
-        block = acb->block_buffer;
-        if (block == NULL) {
-            block = g_malloc(s->block_size);
-            acb->block_buffer = block;
-            acb->bmap_first = block_index;
-            assert(!acb->header_modified);
-            acb->header_modified = 1;
-        }
-        acb->bmap_last = block_index;
-        /* Copy data to be written to new block and zero unused parts. */
-        memset(block, 0, sector_in_block * SECTOR_SIZE);
-        memcpy(block + sector_in_block * SECTOR_SIZE,
-               acb->buf, n_sectors * SECTOR_SIZE);
-        memset(block + (sector_in_block + n_sectors) * SECTOR_SIZE, 0,
-               (s->block_sectors - n_sectors - sector_in_block) * SECTOR_SIZE);
-        acb->hd_iov.iov_base = (void *)block;
-        acb->hd_iov.iov_len = s->block_size;
-        qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
-        acb->hd_aiocb = bdrv_aio_writev(bs->file, offset,
-                                        &acb->hd_qiov, s->block_sectors,
-                                        vdi_aio_write_cb, acb);
-    } else {
-        uint64_t offset = s->header.offset_data / SECTOR_SIZE +
-                          (uint64_t)bmap_entry * s->block_sectors +
-                          sector_in_block;
-        acb->hd_iov.iov_base = (void *)acb->buf;
-        acb->hd_iov.iov_len = n_sectors * SECTOR_SIZE;
-        qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
-        acb->hd_aiocb = bdrv_aio_writev(bs->file, offset, &acb->hd_qiov,
-                                        n_sectors, vdi_aio_write_cb, acb);
+    logout("finished data write\n");
+    if (ret < 0) {
+        return ret;
     }
 
-    return;
-
-done:
-    if (acb->qiov->niov > 1) {
-        qemu_vfree(acb->orig_buf);
-    }
-    acb->common.cb(acb->common.opaque, ret);
-    qemu_aio_release(acb);
-}
+    if (block) {
+        /* One or more new blocks were allocated. */
+        VdiHeader *header = (VdiHeader *) block;
+        uint8_t *base;
+        uint64_t offset;
 
-static BlockDriverAIOCB *vdi_aio_writev(BlockDriverState *bs,
-        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
-        BlockDriverCompletionFunc *cb, void *opaque)
-{
-    VdiAIOCB *acb;
-    int ret;
+        logout("now writing modified header\n");
+        assert(VDI_IS_ALLOCATED(bmap_first));
+        *header = s->header;
+        vdi_header_to_le(header);
+        ret = bdrv_write(bs->file, 0, block, 1);
+        g_free(block);
+        block = NULL;
 
-    logout("\n");
-    acb = vdi_aio_setup(bs, sector_num, qiov, nb_sectors, cb, opaque, 1);
-    ret = vdi_schedule_bh(vdi_aio_rw_bh, acb);
-    if (ret < 0) {
-        if (acb->qiov->niov > 1) {
-            qemu_vfree(acb->orig_buf);
+        if (ret < 0) {
+            return ret;
         }
-        qemu_aio_release(acb);
-        return NULL;
+
+        logout("now writing modified block map entry %u...%u\n",
+               bmap_first, bmap_last);
+        /* Write modified sectors from block map. */
+        bmap_first /= (SECTOR_SIZE / sizeof(uint32_t));
+        bmap_last /= (SECTOR_SIZE / sizeof(uint32_t));
+        n_sectors = bmap_last - bmap_first + 1;
+        offset = s->bmap_sector + bmap_first;
+        base = ((uint8_t *)&s->bmap[0]) + bmap_first * SECTOR_SIZE;
+        logout("will write %u block map sectors starting from entry %u\n",
+               n_sectors, bmap_first);
+        ret = bdrv_write(bs->file, offset, base, n_sectors);
     }
 
-    return &acb->common;
+    return ret;
 }
 
 static int vdi_create(const char *filename, QEMUOptionParameter *options)
@@ -930,13 +725,6 @@ static void vdi_close(BlockDriverState *bs)
     error_free(s->migration_blocker);
 }
 
-static coroutine_fn int vdi_co_flush(BlockDriverState *bs)
-{
-    logout("\n");
-    return bdrv_co_flush(bs->file);
-}
-
-
 static QEMUOptionParameter vdi_create_options[] = {
     {
         .name = BLOCK_OPT_SIZE,
@@ -969,13 +757,12 @@ static BlockDriver bdrv_vdi = {
     .bdrv_open = vdi_open,
     .bdrv_close = vdi_close,
     .bdrv_create = vdi_create,
-    .bdrv_co_flush_to_disk = vdi_co_flush,
     .bdrv_co_is_allocated = vdi_co_is_allocated,
     .bdrv_make_empty = vdi_make_empty,
 
-    .bdrv_aio_readv = vdi_aio_readv,
+    .bdrv_read = vdi_co_read,
 #if defined(CONFIG_VDI_WRITE)
-    .bdrv_aio_writev = vdi_aio_writev,
+    .bdrv_write = vdi_co_write,
 #endif
 
     .bdrv_get_info = vdi_get_info,
diff --git a/block/vmdk.c b/block/vmdk.c
index 45c003a0f1..18e9b4caf6 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -1525,10 +1525,10 @@ static void vmdk_close(BlockDriverState *bs)
 
 static coroutine_fn int vmdk_co_flush(BlockDriverState *bs)
 {
-    int i, ret, err;
     BDRVVmdkState *s = bs->opaque;
+    int i, err;
+    int ret = 0;
 
-    ret = bdrv_co_flush(bs->file);
     for (i = 0; i < s->num_extents; i++) {
         err = bdrv_co_flush(s->extents[i].file);
         if (err < 0) {
diff --git a/block/vpc.c b/block/vpc.c
index 6b4816f563..5cd13d17a1 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -189,6 +189,9 @@ static int vpc_open(BlockDriverState *bs, int flags)
         fprintf(stderr, "block-vpc: The header checksum of '%s' is "
             "incorrect.\n", bs->filename);
 
+    /* Write 'checksum' back to footer, or else will leave it with zero. */
+    footer->checksum = be32_to_cpu(checksum);
+
     // The visible size of a image in Virtual PC depends on the geometry
     // rather than on the size stored in the footer (the size in the footer
     // is too large usually)
@@ -507,11 +510,6 @@ static coroutine_fn int vpc_co_write(BlockDriverState *bs, int64_t sector_num,
     return ret;
 }
 
-static coroutine_fn int vpc_co_flush(BlockDriverState *bs)
-{
-    return bdrv_co_flush(bs->file);
-}
-
 /*
  * Calculates the number of cylinders, heads and sectors per cylinder
  * based on a given number of sectors. This is the algorithm described
@@ -789,7 +787,6 @@ static BlockDriver bdrv_vpc = {
 
     .bdrv_read              = vpc_co_read,
     .bdrv_write             = vpc_co_write,
-    .bdrv_co_flush_to_disk  = vpc_co_flush,
 
     .create_options = vpc_create_options,
 };