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

Block layer patches:

- iotests: Fix output of qemu-io related tests
- Don't ignore bdrv_set_aio_context() for nodes with bs->drv = NUL
- vmdk: Set vmdk parent backing_format to vmdk
- qcow2: Preallocation fixes (especially for external data files)
- Add linear-buffer-based APIs (as wrappers around qiov-based ones)
- Various code cleanups and small corner case fixes

# gpg: Signature made Tue 30 Apr 2019 16:35:09 BST
# gpg:                using RSA key 7F09B272C88F2FD6
# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>" [full]
# Primary key fingerprint: DC3D EB15 9A9A F95D 3D74  56FE 7F09 B272 C88F 2FD6

* remotes/kevin/tags/for-upstream: (27 commits)
  block/qed: add missed coroutine_fn markers
  iotests: Check that images are in read-only mode after block-commit
  commit: Make base read-only if there is an early failure
  qemu-img: use buffer-based io
  block/stream: use buffer-based io
  block/commit: use buffer-based io
  block/backup: use buffer-based io
  block/parallels: use buffer-based io
  block/qed: use buffer-based io
  block/qcow: use buffer-based io
  block/qcow2: use buffer-based io
  block: introduce byte-based io helpers
  qcow2: Fix error handling in the compression code
  qcow2: Fix qcow2_make_empty() with external data file
  qemu-img: Make create hint at protocol options
  iotests: Perform the correct test in 082
  qcow2: Fix full preallocation with external data file
  qcow2: Add errp to preallocate_co()
  qcow2: Avoid COW during metadata preallocation
  qemu-img: Saner printing of large file sizes
  ...

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

75 files changed, 696 insertions, 519 deletions

diff --git a/block.c b/block.c
index 16615bc876..9ae5c0ed2f 100644
--- a/block.c
+++ b/block.c
@@ -5672,10 +5672,6 @@ void bdrv_detach_aio_context(BlockDriverState *bs)
     BdrvAioNotifier *baf, *baf_tmp;
     BdrvChild *child;
 
-    if (!bs->drv) {
-        return;
-    }
-
     assert(!bs->walking_aio_notifiers);
     bs->walking_aio_notifiers = true;
     QLIST_FOREACH_SAFE(baf, &bs->aio_notifiers, list, baf_tmp) {
@@ -5690,7 +5686,7 @@ void bdrv_detach_aio_context(BlockDriverState *bs)
      */
     bs->walking_aio_notifiers = false;
 
-    if (bs->drv->bdrv_detach_aio_context) {
+    if (bs->drv && bs->drv->bdrv_detach_aio_context) {
         bs->drv->bdrv_detach_aio_context(bs);
     }
     QLIST_FOREACH(child, &bs->children, next) {
@@ -5709,10 +5705,6 @@ void bdrv_attach_aio_context(BlockDriverState *bs,
     BdrvAioNotifier *ban, *ban_tmp;
     BdrvChild *child;
 
-    if (!bs->drv) {
-        return;
-    }
-
     if (bs->quiesce_counter) {
         aio_disable_external(new_context);
     }
@@ -5722,7 +5714,7 @@ void bdrv_attach_aio_context(BlockDriverState *bs,
     QLIST_FOREACH(child, &bs->children, next) {
         bdrv_attach_aio_context(child->bs, new_context);
     }
-    if (bs->drv->bdrv_attach_aio_context) {
+    if (bs->drv && bs->drv->bdrv_attach_aio_context) {
         bs->drv->bdrv_attach_aio_context(bs, new_context);
     }
 
diff --git a/block/backup.c b/block/backup.c
index 9988753249..910ed764aa 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -107,7 +107,6 @@ static int coroutine_fn backup_cow_with_bounce_buffer(BackupBlockJob *job,
                                                       void **bounce_buffer)
 {
     int ret;
-    QEMUIOVector qiov;
     BlockBackend *blk = job->common.blk;
     int nbytes;
     int read_flags = is_write_notifier ? BDRV_REQ_NO_SERIALISING : 0;
@@ -118,9 +117,8 @@ static int coroutine_fn backup_cow_with_bounce_buffer(BackupBlockJob *job,
     if (!*bounce_buffer) {
         *bounce_buffer = blk_blockalign(blk, job->cluster_size);
     }
-    qemu_iovec_init_buf(&qiov, *bounce_buffer, nbytes);
 
-    ret = blk_co_preadv(blk, start, qiov.size, &qiov, read_flags);
+    ret = blk_co_pread(blk, start, nbytes, *bounce_buffer, read_flags);
     if (ret < 0) {
         trace_backup_do_cow_read_fail(job, start, ret);
         if (error_is_read) {
@@ -129,13 +127,13 @@ static int coroutine_fn backup_cow_with_bounce_buffer(BackupBlockJob *job,
         goto fail;
     }
 
-    if (qemu_iovec_is_zero(&qiov)) {
+    if (buffer_is_zero(*bounce_buffer, nbytes)) {
         ret = blk_co_pwrite_zeroes(job->target, start,
-                                   qiov.size, write_flags | BDRV_REQ_MAY_UNMAP);
+                                   nbytes, write_flags | BDRV_REQ_MAY_UNMAP);
     } else {
-        ret = blk_co_pwritev(job->target, start,
-                             qiov.size, &qiov, write_flags |
-                             (job->compress ? BDRV_REQ_WRITE_COMPRESSED : 0));
+        ret = blk_co_pwrite(job->target, start,
+                            nbytes, *bounce_buffer, write_flags |
+                            (job->compress ? BDRV_REQ_WRITE_COMPRESSED : 0));
     }
     if (ret < 0) {
         trace_backup_do_cow_write_fail(job, start, ret);
diff --git a/block/commit.c b/block/commit.c
index ba60fef58a..27537d995b 100644
--- a/block/commit.c
+++ b/block/commit.c
@@ -48,16 +48,15 @@ static int coroutine_fn commit_populate(BlockBackend *bs, BlockBackend *base,
                                         void *buf)
 {
     int ret = 0;
-    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
 
     assert(bytes < SIZE_MAX);
 
-    ret = blk_co_preadv(bs, offset, qiov.size, &qiov, 0);
+    ret = blk_co_pread(bs, offset, bytes, buf, 0);
     if (ret < 0) {
         return ret;
     }
 
-    ret = blk_co_pwritev(base, offset, qiov.size, &qiov, 0);
+    ret = blk_co_pwrite(base, offset, bytes, buf, 0);
     if (ret < 0) {
         return ret;
     }
@@ -384,6 +383,9 @@ fail:
     if (s->top) {
         blk_unref(s->top);
     }
+    if (s->base_read_only) {
+        bdrv_reopen_set_read_only(base, true, NULL);
+    }
     job_early_fail(&s->common.job);
     /* commit_top_bs has to be replaced after deleting the block job,
      * otherwise this would fail because of lack of permissions. */
diff --git a/block/parallels.c b/block/parallels.c
index 15bc97b759..2747400577 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -220,20 +220,18 @@ static int64_t allocate_clusters(BlockDriverState *bs, int64_t sector_num,
     if (bs->backing) {
         int64_t nb_cow_sectors = to_allocate * s->tracks;
         int64_t nb_cow_bytes = nb_cow_sectors << BDRV_SECTOR_BITS;
-        QEMUIOVector qiov =
-            QEMU_IOVEC_INIT_BUF(qiov, qemu_blockalign(bs, nb_cow_bytes),
-                                nb_cow_bytes);
+        void *buf = qemu_blockalign(bs, nb_cow_bytes);
 
-        ret = bdrv_co_preadv(bs->backing, idx * s->tracks * BDRV_SECTOR_SIZE,
-                             nb_cow_bytes, &qiov, 0);
+        ret = bdrv_co_pread(bs->backing, idx * s->tracks * BDRV_SECTOR_SIZE,
+                            nb_cow_bytes, buf, 0);
         if (ret < 0) {
-            qemu_vfree(qemu_iovec_buf(&qiov));
+            qemu_vfree(buf);
             return ret;
         }
 
         ret = bdrv_co_pwritev(bs->file, s->data_end * BDRV_SECTOR_SIZE,
-                              nb_cow_bytes, &qiov, 0);
-        qemu_vfree(qemu_iovec_buf(&qiov));
+                              nb_cow_bytes, buf, 0);
+        qemu_vfree(buf);
         if (ret < 0) {
             return ret;
         }
diff --git a/block/qapi.c b/block/qapi.c
index e3e74f898f..0c13c86f4e 100644
--- a/block/qapi.c
+++ b/block/qapi.c
@@ -631,42 +631,13 @@ BlockStatsList *qmp_query_blockstats(bool has_query_nodes,
     return head;
 }
 
-#define NB_SUFFIXES 4
-
-static char *get_human_readable_size(char *buf, int buf_size, int64_t size)
-{
-    static const char suffixes[NB_SUFFIXES] = {'K', 'M', 'G', 'T'};
-    int64_t base;
-    int i;
-
-    if (size <= 999) {
-        snprintf(buf, buf_size, "%" PRId64, size);
-    } else {
-        base = 1024;
-        for (i = 0; i < NB_SUFFIXES; i++) {
-            if (size < (10 * base)) {
-                snprintf(buf, buf_size, "%0.1f%c",
-                         (double)size / base,
-                         suffixes[i]);
-                break;
-            } else if (size < (1000 * base) || i == (NB_SUFFIXES - 1)) {
-                snprintf(buf, buf_size, "%" PRId64 "%c",
-                         ((size + (base >> 1)) / base),
-                         suffixes[i]);
-                break;
-            }
-            base = base * 1024;
-        }
-    }
-    return buf;
-}
-
 void bdrv_snapshot_dump(QEMUSnapshotInfo *sn)
 {
-    char buf1[128], date_buf[128], clock_buf[128];
+    char date_buf[128], clock_buf[128];
     struct tm tm;
     time_t ti;
     int64_t secs;
+    char *sizing = NULL;
 
     if (!sn) {
         qemu_printf("%-10s%-20s%7s%20s%15s",
@@ -683,13 +654,14 @@ void bdrv_snapshot_dump(QEMUSnapshotInfo *sn)
                  (int)((secs / 60) % 60),
                  (int)(secs % 60),
                  (int)((sn->vm_clock_nsec / 1000000) % 1000));
+        sizing = size_to_str(sn->vm_state_size);
         qemu_printf("%-10s%-20s%7s%20s%15s",
                     sn->id_str, sn->name,
-                    get_human_readable_size(buf1, sizeof(buf1),
-                                            sn->vm_state_size),
+                    sizing,
                     date_buf,
                     clock_buf);
     }
+    g_free(sizing);
 }
 
 static void dump_qdict(int indentation, QDict *dict);
@@ -787,14 +759,13 @@ void bdrv_image_info_specific_dump(ImageInfoSpecific *info_spec)
 
 void bdrv_image_info_dump(ImageInfo *info)
 {
-    char size_buf[128], dsize_buf[128];
+    char *size_buf, *dsize_buf;
     if (!info->has_actual_size) {
-        snprintf(dsize_buf, sizeof(dsize_buf), "unavailable");
+        dsize_buf = g_strdup("unavailable");
     } else {
-        get_human_readable_size(dsize_buf, sizeof(dsize_buf),
-                                info->actual_size);
+        dsize_buf = size_to_str(info->actual_size);
     }
-    get_human_readable_size(size_buf, sizeof(size_buf), info->virtual_size);
+    size_buf = size_to_str(info->virtual_size);
     qemu_printf("image: %s\n"
                 "file format: %s\n"
                 "virtual size: %s (%" PRId64 " bytes)\n"
@@ -802,6 +773,8 @@ void bdrv_image_info_dump(ImageInfo *info)
                 info->filename, info->format, size_buf,
                 info->virtual_size,
                 dsize_buf);
+    g_free(size_buf);
+    g_free(dsize_buf);
 
     if (info->has_encrypted && info->encrypted) {
         qemu_printf("encrypted: yes\n");
diff --git a/block/qcow.c b/block/qcow.c
index 10d2cf14b3..1bb8fd05e2 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -631,7 +631,6 @@ static coroutine_fn int qcow_co_preadv(BlockDriverState *bs, uint64_t offset,
     int offset_in_cluster;
     int ret = 0, n;
     uint64_t cluster_offset;
-    QEMUIOVector hd_qiov;
     uint8_t *buf;
     void *orig_buf;
 
@@ -663,11 +662,10 @@ static coroutine_fn int qcow_co_preadv(BlockDriverState *bs, uint64_t offset,
         if (!cluster_offset) {
             if (bs->backing) {
                 /* read from the base image */
-                qemu_iovec_init_buf(&hd_qiov, buf, n);
                 qemu_co_mutex_unlock(&s->lock);
                 /* qcow2 emits this on bs->file instead of bs->backing */
                 BLKDBG_EVENT(bs->file, BLKDBG_READ_BACKING_AIO);
-                ret = bdrv_co_preadv(bs->backing, offset, n, &hd_qiov, 0);
+                ret = bdrv_co_pread(bs->backing, offset, n, buf, 0);
                 qemu_co_mutex_lock(&s->lock);
                 if (ret < 0) {
                     break;
@@ -688,11 +686,10 @@ static coroutine_fn int qcow_co_preadv(BlockDriverState *bs, uint64_t offset,
                 ret = -EIO;
                 break;
             }
-            qemu_iovec_init_buf(&hd_qiov, buf, n);
             qemu_co_mutex_unlock(&s->lock);
             BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO);
-            ret = bdrv_co_preadv(bs->file, cluster_offset + offset_in_cluster,
-                                 n, &hd_qiov, 0);
+            ret = bdrv_co_pread(bs->file, cluster_offset + offset_in_cluster,
+                                n, buf, 0);
             qemu_co_mutex_lock(&s->lock);
             if (ret < 0) {
                 break;
@@ -731,7 +728,6 @@ static coroutine_fn int qcow_co_pwritev(BlockDriverState *bs, uint64_t offset,
     int offset_in_cluster;
     uint64_t cluster_offset;
     int ret = 0, n;
-    QEMUIOVector hd_qiov;
     uint8_t *buf;
     void *orig_buf;
 
@@ -776,11 +772,10 @@ static coroutine_fn int qcow_co_pwritev(BlockDriverState *bs, uint64_t offset,
             }
         }
 
-        qemu_iovec_init_buf(&hd_qiov, buf, n);
         qemu_co_mutex_unlock(&s->lock);
         BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO);
-        ret = bdrv_co_pwritev(bs->file, cluster_offset + offset_in_cluster,
-                              n, &hd_qiov, 0);
+        ret = bdrv_co_pwrite(bs->file, cluster_offset + offset_in_cluster,
+                             n, buf, 0);
         qemu_co_mutex_lock(&s->lock);
         if (ret < 0) {
             break;
@@ -1056,7 +1051,6 @@ qcow_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
                            uint64_t bytes, QEMUIOVector *qiov)
 {
     BDRVQcowState *s = bs->opaque;
-    QEMUIOVector hd_qiov;
     z_stream strm;
     int ret, out_len;
     uint8_t *buf, *out_buf;
@@ -1122,9 +1116,8 @@ qcow_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
     }
     cluster_offset &= s->cluster_offset_mask;
 
-    qemu_iovec_init_buf(&hd_qiov, out_buf, out_len);
     BLKDBG_EVENT(bs->file, BLKDBG_WRITE_COMPRESSED);
-    ret = bdrv_co_pwritev(bs->file, cluster_offset, out_len, &hd_qiov, 0);
+    ret = bdrv_co_pwrite(bs->file, cluster_offset, out_len, out_buf, 0);
     if (ret < 0) {
         goto fail;
     }
diff --git a/block/qcow2.c b/block/qcow2.c
index 3ace3b2209..a520d116ef 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -2721,11 +2721,13 @@ static int qcow2_set_up_encryption(BlockDriverState *bs,
  * Returns: 0 on success, -errno on failure.
  */
 static int coroutine_fn preallocate_co(BlockDriverState *bs, uint64_t offset,
-                                       uint64_t new_length)
+                                       uint64_t new_length, PreallocMode mode,
+                                       Error **errp)
 {
     BDRVQcow2State *s = bs->opaque;
     uint64_t bytes;
     uint64_t host_offset = 0;
+    int64_t file_length;
     unsigned int cur_bytes;
     int ret;
     QCowL2Meta *meta;
@@ -2734,10 +2736,11 @@ static int coroutine_fn preallocate_co(BlockDriverState *bs, uint64_t offset,
     bytes = new_length - offset;
 
     while (bytes) {
-        cur_bytes = MIN(bytes, INT_MAX);
+        cur_bytes = MIN(bytes, QEMU_ALIGN_DOWN(INT_MAX, s->cluster_size));
         ret = qcow2_alloc_cluster_offset(bs, offset, &cur_bytes,
                                          &host_offset, &meta);
         if (ret < 0) {
+            error_setg_errno(errp, -ret, "Allocating clusters failed");
             return ret;
         }
 
@@ -2746,6 +2749,7 @@ static int coroutine_fn preallocate_co(BlockDriverState *bs, uint64_t offset,
 
             ret = qcow2_alloc_cluster_link_l2(bs, meta);
             if (ret < 0) {
+                error_setg_errno(errp, -ret, "Mapping clusters failed");
                 qcow2_free_any_clusters(bs, meta->alloc_offset,
                                         meta->nb_clusters, QCOW2_DISCARD_NEVER);
                 return ret;
@@ -2770,10 +2774,18 @@ static int coroutine_fn preallocate_co(BlockDriverState *bs, uint64_t offset,
      * all of the allocated clusters (otherwise we get failing reads after
      * EOF). Extend the image to the last allocated sector.
      */
-    if (host_offset != 0) {
-        uint8_t data = 0;
-        ret = bdrv_pwrite(s->data_file, (host_offset + cur_bytes) - 1,
-                          &data, 1);
+    file_length = bdrv_getlength(s->data_file->bs);
+    if (file_length < 0) {
+        error_setg_errno(errp, -file_length, "Could not get file size");
+        return file_length;
+    }
+
+    if (host_offset + cur_bytes > file_length) {
+        if (mode == PREALLOC_MODE_METADATA) {
+            mode = PREALLOC_MODE_OFF;
+        }
+        ret = bdrv_co_truncate(s->data_file, host_offset + cur_bytes, mode,
+                               errp);
         if (ret < 0) {
             return ret;
         }
@@ -3745,12 +3757,17 @@ static int coroutine_fn qcow2_co_truncate(BlockDriverState *bs, int64_t offset,
 
     switch (prealloc) {
     case PREALLOC_MODE_OFF:
+        if (has_data_file(bs)) {
+            ret = bdrv_co_truncate(s->data_file, offset, prealloc, errp);
+            if (ret < 0) {
+                goto fail;
+            }
+        }
         break;
 
     case PREALLOC_MODE_METADATA:
-        ret = preallocate_co(bs, old_length, offset);
+        ret = preallocate_co(bs, old_length, offset, prealloc, errp);
         if (ret < 0) {
-            error_setg_errno(errp, -ret, "Preallocation failed");
             goto fail;
         }
         break;
@@ -3766,9 +3783,8 @@ static int coroutine_fn qcow2_co_truncate(BlockDriverState *bs, int64_t offset,
         /* With a data file, preallocation means just allocating the metadata
          * and forwarding the truncate request to the data file */
         if (has_data_file(bs)) {
-            ret = preallocate_co(bs, old_length, offset);
+            ret = preallocate_co(bs, old_length, offset, prealloc, errp);
             if (ret < 0) {
-                error_setg_errno(errp, -ret, "Preallocation failed");
                 goto fail;
             }
             break;
@@ -3882,16 +3898,6 @@ static int coroutine_fn qcow2_co_truncate(BlockDriverState *bs, int64_t offset,
 
     bs->total_sectors = offset / BDRV_SECTOR_SIZE;
 
-    if (has_data_file(bs)) {
-        if (prealloc == PREALLOC_MODE_METADATA) {
-            prealloc = PREALLOC_MODE_OFF;
-        }
-        ret = bdrv_co_truncate(s->data_file, offset, prealloc, errp);
-        if (ret < 0) {
-            goto fail;
-        }
-    }
-
     /* write updated header.size */
     offset = cpu_to_be64(offset);
     ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, size),
@@ -3923,8 +3929,8 @@ fail:
  * @src - source buffer, @src_size bytes
  *
  * Returns: compressed size on success
- *          -1 destination buffer is not enough to store compressed data
- *          -2 on any other error
+ *          -ENOMEM destination buffer is not enough to store compressed data
+ *          -EIO    on any other error
  */
 static ssize_t qcow2_compress(void *dest, size_t dest_size,
                               const void *src, size_t src_size)
@@ -3937,7 +3943,7 @@ static ssize_t qcow2_compress(void *dest, size_t dest_size,
     ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION, Z_DEFLATED,
                        -12, 9, Z_DEFAULT_STRATEGY);
     if (ret != Z_OK) {
-        return -2;
+        return -EIO;
     }
 
     /* strm.next_in is not const in old zlib versions, such as those used on
@@ -3951,7 +3957,7 @@ static ssize_t qcow2_compress(void *dest, size_t dest_size,
     if (ret == Z_STREAM_END) {
         ret = dest_size - strm.avail_out;
     } else {
-        ret = (ret == Z_OK ? -1 : -2);
+        ret = (ret == Z_OK ? -ENOMEM : -EIO);
     }
 
     deflateEnd(&strm);
@@ -4088,9 +4094,8 @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
                             uint64_t bytes, QEMUIOVector *qiov)
 {
     BDRVQcow2State *s = bs->opaque;
-    QEMUIOVector hd_qiov;
     int ret;
-    size_t out_len;
+    ssize_t out_len;
     uint8_t *buf, *out_buf;
     uint64_t cluster_offset;
 
@@ -4129,16 +4134,16 @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
 
     out_len = qcow2_co_compress(bs, out_buf, s->cluster_size - 1,
                                 buf, s->cluster_size);
-    if (out_len == -2) {
-        ret = -EINVAL;
-        goto fail;
-    } else if (out_len == -1) {
+    if (out_len == -ENOMEM) {
         /* could not compress: write normal cluster */
         ret = qcow2_co_pwritev(bs, offset, bytes, qiov, 0);
         if (ret < 0) {
             goto fail;
         }
         goto success;
+    } else if (out_len < 0) {
+        ret = -EINVAL;
+        goto fail;
     }
 
     qemu_co_mutex_lock(&s->lock);
@@ -4155,10 +4160,8 @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
         goto fail;
     }
 
-    qemu_iovec_init_buf(&hd_qiov, out_buf, out_len);
-
     BLKDBG_EVENT(s->data_file, BLKDBG_WRITE_COMPRESSED);
-    ret = bdrv_co_pwritev(s->data_file, cluster_offset, out_len, &hd_qiov, 0);
+    ret = bdrv_co_pwrite(s->data_file, cluster_offset, out_len, out_buf, 0);
     if (ret < 0) {
         goto fail;
     }
@@ -4181,7 +4184,6 @@ qcow2_co_preadv_compressed(BlockDriverState *bs,
     int ret = 0, csize, nb_csectors;
     uint64_t coffset;
     uint8_t *buf, *out_buf;
-    QEMUIOVector local_qiov;
     int offset_in_cluster = offset_into_cluster(s, offset);
 
     coffset = file_cluster_offset & s->cluster_offset_mask;
@@ -4192,12 +4194,11 @@ qcow2_co_preadv_compressed(BlockDriverState *bs,
     if (!buf) {
         return -ENOMEM;
     }
-    qemu_iovec_init_buf(&local_qiov, buf, csize);
 
     out_buf = qemu_blockalign(bs, s->cluster_size);
 
     BLKDBG_EVENT(bs->file, BLKDBG_READ_COMPRESSED);
-    ret = bdrv_co_preadv(bs->file, coffset, csize, &local_qiov, 0);
+    ret = bdrv_co_pread(bs->file, coffset, csize, buf, 0);
     if (ret < 0) {
         goto fail;
     }
@@ -4378,14 +4379,17 @@ static int qcow2_make_empty(BlockDriverState *bs)
 
     if (s->qcow_version >= 3 && !s->snapshots && !s->nb_bitmaps &&
         3 + l1_clusters <= s->refcount_block_size &&
-        s->crypt_method_header != QCOW_CRYPT_LUKS) {
+        s->crypt_method_header != QCOW_CRYPT_LUKS &&
+        !has_data_file(bs)) {
         /* The following function only works for qcow2 v3 images (it
          * requires the dirty flag) and only as long as there are no
          * features that reserve extra clusters (such as snapshots,
          * LUKS header, or persistent bitmaps), because it completely
          * empties the image.  Furthermore, the L1 table and three
          * additional clusters (image header, refcount table, one
-         * refcount block) have to fit inside one refcount block. */
+         * refcount block) have to fit inside one refcount block. It
+         * only resets the image file, i.e. does not work with an
+         * external data file. */
         return make_completely_empty(bs);
     }
 
diff --git a/block/qed-check.c b/block/qed-check.c
index 0edac03159..418033ee24 100644
--- a/block/qed-check.c
+++ b/block/qed-check.c
@@ -106,7 +106,7 @@ static unsigned int qed_check_l2_table(QEDCheck *check, QEDTable *table)
 /**
  * Descend tables and check each cluster is referenced once only
  */
-static int qed_check_l1_table(QEDCheck *check, QEDTable *table)
+static int coroutine_fn qed_check_l1_table(QEDCheck *check, QEDTable *table)
 {
     BDRVQEDState *s = check->s;
     unsigned int i, num_invalid_l1 = 0;
@@ -218,7 +218,7 @@ static void qed_check_mark_clean(BDRVQEDState *s, BdrvCheckResult *result)
 }
 
 /* Called with table_lock held.  */
-int qed_check(BDRVQEDState *s, BdrvCheckResult *result, bool fix)
+int coroutine_fn qed_check(BDRVQEDState *s, BdrvCheckResult *result, bool fix)
 {
     QEDCheck check = {
         .s = s,
diff --git a/block/qed-table.c b/block/qed-table.c
index c497bd4aec..405d446cbe 100644
--- a/block/qed-table.c
+++ b/block/qed-table.c
@@ -19,24 +19,25 @@
 #include "qemu/bswap.h"
 
 /* Called with table_lock held.  */
-static int qed_read_table(BDRVQEDState *s, uint64_t offset, QEDTable *table)
+static int coroutine_fn qed_read_table(BDRVQEDState *s, uint64_t offset,
+                                       QEDTable *table)
 {
-    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(
-        qiov, table->offsets, s->header.cluster_size * s->header.table_size);
+    unsigned int bytes = s->header.cluster_size * s->header.table_size;
+
     int noffsets;
     int i, ret;
 
     trace_qed_read_table(s, offset, table);
 
     qemu_co_mutex_unlock(&s->table_lock);
-    ret = bdrv_preadv(s->bs->file, offset, &qiov);
+    ret = bdrv_co_pread(s->bs->file, offset, bytes, table->offsets, 0);
     qemu_co_mutex_lock(&s->table_lock);
     if (ret < 0) {
         goto out;
     }
 
     /* Byteswap offsets */
-    noffsets = qiov.size / sizeof(uint64_t);
+    noffsets = bytes / sizeof(uint64_t);
     for (i = 0; i < noffsets; i++) {
         table->offsets[i] = le64_to_cpu(table->offsets[i]);
     }
@@ -60,13 +61,13 @@ out:
  *
  * Called with table_lock held.
  */
-static int qed_write_table(BDRVQEDState *s, uint64_t offset, QEDTable *table,
-                           unsigned int index, unsigned int n, bool flush)
+static int coroutine_fn qed_write_table(BDRVQEDState *s, uint64_t offset,
+                                        QEDTable *table, unsigned int index,
+                                        unsigned int n, bool flush)
 {
     unsigned int sector_mask = BDRV_SECTOR_SIZE / sizeof(uint64_t) - 1;
     unsigned int start, end, i;
     QEDTable *new_table;
-    QEMUIOVector qiov;
     size_t len_bytes;
     int ret;
 
@@ -79,7 +80,6 @@ static int qed_write_table(BDRVQEDState *s, uint64_t offset, QEDTable *table,
     len_bytes = (end - start) * sizeof(uint64_t);
 
     new_table = qemu_blockalign(s->bs, len_bytes);
-    qemu_iovec_init_buf(&qiov, new_table->offsets, len_bytes);
 
     /* Byteswap table */
     for (i = start; i < end; i++) {
@@ -91,7 +91,7 @@ static int qed_write_table(BDRVQEDState *s, uint64_t offset, QEDTable *table,
     offset += start * sizeof(uint64_t);
 
     qemu_co_mutex_unlock(&s->table_lock);
-    ret = bdrv_pwritev(s->bs->file, offset, &qiov);
+    ret = bdrv_co_pwrite(s->bs->file, offset, len_bytes, new_table->offsets, 0);
     qemu_co_mutex_lock(&s->table_lock);
     trace_qed_write_table_cb(s, table, flush, ret);
     if (ret < 0) {
@@ -111,27 +111,29 @@ out:
     return ret;
 }
 
-int qed_read_l1_table_sync(BDRVQEDState *s)
+int coroutine_fn qed_read_l1_table_sync(BDRVQEDState *s)
 {
     return qed_read_table(s, s->header.l1_table_offset, s->l1_table);
 }
 
 /* Called with table_lock held.  */
-int qed_write_l1_table(BDRVQEDState *s, unsigned int index, unsigned int n)
+int coroutine_fn qed_write_l1_table(BDRVQEDState *s, unsigned int index,
+                                    unsigned int n)
 {
     BLKDBG_EVENT(s->bs->file, BLKDBG_L1_UPDATE);
     return qed_write_table(s, s->header.l1_table_offset,
                            s->l1_table, index, n, false);
 }
 
-int qed_write_l1_table_sync(BDRVQEDState *s, unsigned int index,
-                            unsigned int n)
+int coroutine_fn qed_write_l1_table_sync(BDRVQEDState *s, unsigned int index,
+                                         unsigned int n)
 {
     return qed_write_l1_table(s, index, n);
 }
 
 /* Called with table_lock held.  */
-int qed_read_l2_table(BDRVQEDState *s, QEDRequest *request, uint64_t offset)
+int coroutine_fn qed_read_l2_table(BDRVQEDState *s, QEDRequest *request,
+                                   uint64_t offset)
 {
     int ret;
 
@@ -168,22 +170,25 @@ int qed_read_l2_table(BDRVQEDState *s, QEDRequest *request, uint64_t offset)
     return ret;
 }
 
-int qed_read_l2_table_sync(BDRVQEDState *s, QEDRequest *request, uint64_t offset)
+int coroutine_fn qed_read_l2_table_sync(BDRVQEDState *s, QEDRequest *request,
+                                        uint64_t offset)
 {
     return qed_read_l2_table(s, request, offset);
 }
 
 /* Called with table_lock held.  */
-int qed_write_l2_table(BDRVQEDState *s, QEDRequest *request,
-                       unsigned int index, unsigned int n, bool flush)
+int coroutine_fn qed_write_l2_table(BDRVQEDState *s, QEDRequest *request,
+                                    unsigned int index, unsigned int n,
+                                    bool flush)
 {
     BLKDBG_EVENT(s->bs->file, BLKDBG_L2_UPDATE);
     return qed_write_table(s, request->l2_table->offset,
                            request->l2_table->table, index, n, flush);
 }
 
-int qed_write_l2_table_sync(BDRVQEDState *s, QEDRequest *request,
-                            unsigned int index, unsigned int n, bool flush)
+int coroutine_fn qed_write_l2_table_sync(BDRVQEDState *s, QEDRequest *request,
+                                         unsigned int index, unsigned int n,
+                                         bool flush)
 {
     return qed_write_l2_table(s, request, index, n, flush);
 }
diff --git a/block/qed.c b/block/qed.c
index 89af05d524..dcdcd62b4a 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -113,15 +113,13 @@ static int coroutine_fn qed_write_header(BDRVQEDState *s)
     int nsectors = DIV_ROUND_UP(sizeof(QEDHeader), BDRV_SECTOR_SIZE);
     size_t len = nsectors * BDRV_SECTOR_SIZE;
     uint8_t *buf;
-    QEMUIOVector qiov;
     int ret;
 
     assert(s->allocating_acb || s->allocating_write_reqs_plugged);
 
     buf = qemu_blockalign(s->bs, len);
-    qemu_iovec_init_buf(&qiov, buf, len);
 
-    ret = bdrv_co_preadv(s->bs->file, 0, qiov.size, &qiov, 0);
+    ret = bdrv_co_pread(s->bs->file, 0, len, buf, 0);
     if (ret < 0) {
         goto out;
     }
@@ -129,7 +127,7 @@ static int coroutine_fn qed_write_header(BDRVQEDState *s)
     /* Update header */
     qed_header_cpu_to_le(&s->header, (QEDHeader *) buf);
 
-    ret = bdrv_co_pwritev(s->bs->file, 0, qiov.size,  &qiov, 0);
+    ret = bdrv_co_pwrite(s->bs->file, 0, len,  buf, 0);
     if (ret < 0) {
         goto out;
     }
@@ -1606,8 +1604,9 @@ static void coroutine_fn bdrv_qed_co_invalidate_cache(BlockDriverState *bs,
     }
 }
 
-static int bdrv_qed_co_check(BlockDriverState *bs, BdrvCheckResult *result,
-                             BdrvCheckMode fix)
+static int coroutine_fn bdrv_qed_co_check(BlockDriverState *bs,
+                                          BdrvCheckResult *result,
+                                          BdrvCheckMode fix)
 {
     BDRVQEDState *s = bs->opaque;
     int ret;
diff --git a/block/qed.h b/block/qed.h
index f35341f134..42c115d822 100644
--- a/block/qed.h
+++ b/block/qed.h
@@ -201,17 +201,21 @@ void qed_commit_l2_cache_entry(L2TableCache *l2_cache, CachedL2Table *l2_table);
 /**
  * Table I/O functions
  */
-int qed_read_l1_table_sync(BDRVQEDState *s);
-int qed_write_l1_table(BDRVQEDState *s, unsigned int index, unsigned int n);
-int qed_write_l1_table_sync(BDRVQEDState *s, unsigned int index,
-                            unsigned int n);
-int qed_read_l2_table_sync(BDRVQEDState *s, QEDRequest *request,
-                           uint64_t offset);
-int qed_read_l2_table(BDRVQEDState *s, QEDRequest *request, uint64_t offset);
-int qed_write_l2_table(BDRVQEDState *s, QEDRequest *request,
-                       unsigned int index, unsigned int n, bool flush);
-int qed_write_l2_table_sync(BDRVQEDState *s, QEDRequest *request,
-                            unsigned int index, unsigned int n, bool flush);
+int coroutine_fn qed_read_l1_table_sync(BDRVQEDState *s);
+int coroutine_fn qed_write_l1_table(BDRVQEDState *s, unsigned int index,
+                                    unsigned int n);
+int coroutine_fn qed_write_l1_table_sync(BDRVQEDState *s, unsigned int index,
+                                         unsigned int n);
+int coroutine_fn qed_read_l2_table_sync(BDRVQEDState *s, QEDRequest *request,
+                                        uint64_t offset);
+int coroutine_fn qed_read_l2_table(BDRVQEDState *s, QEDRequest *request,
+                                   uint64_t offset);
+int coroutine_fn qed_write_l2_table(BDRVQEDState *s, QEDRequest *request,
+                                    unsigned int index, unsigned int n,
+                                    bool flush);
+int coroutine_fn qed_write_l2_table_sync(BDRVQEDState *s, QEDRequest *request,
+                                         unsigned int index, unsigned int n,
+                                         bool flush);
 
 /**
  * Cluster functions
@@ -223,7 +227,7 @@ int coroutine_fn qed_find_cluster(BDRVQEDState *s, QEDRequest *request,
 /**
  * Consistency check
  */
-int qed_check(BDRVQEDState *s, BdrvCheckResult *result, bool fix);
+int coroutine_fn qed_check(BDRVQEDState *s, BdrvCheckResult *result, bool fix);
 
 QEDTable *qed_alloc_table(BDRVQEDState *s);
 
diff --git a/block/stream.c b/block/stream.c
index bfaebb861a..1a906fd860 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -42,12 +42,10 @@ static int coroutine_fn stream_populate(BlockBackend *blk,
                                         int64_t offset, uint64_t bytes,
                                         void *buf)
 {
-    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
-
     assert(bytes < SIZE_MAX);
 
     /* Copy-on-read the unallocated clusters */
-    return blk_co_preadv(blk, offset, qiov.size, &qiov, BDRV_REQ_COPY_ON_READ);
+    return blk_co_pread(blk, offset, bytes, buf, BDRV_REQ_COPY_ON_READ);
 }
 
 static void stream_abort(Job *job)
diff --git a/block/vhdx-log.c b/block/vhdx-log.c
index 3149ff08d8..5e946846f1 100644
--- a/block/vhdx-log.c
+++ b/block/vhdx-log.c
@@ -551,7 +551,7 @@ static int vhdx_log_flush(BlockDriverState *bs, BDRVVHDXState *s,
         }
         if (file_length < desc_entries->hdr.last_file_offset) {
             new_file_size = desc_entries->hdr.last_file_offset;
-            if (new_file_size % (1024*1024)) {
+            if (new_file_size % (1 * MiB)) {
                 /* round up to nearest 1MB boundary */
                 new_file_size = QEMU_ALIGN_UP(new_file_size, MiB);
                 if (new_file_size > INT64_MAX) {
diff --git a/block/vhdx.c b/block/vhdx.c
index b785aef4b7..a143a57657 100644
--- a/block/vhdx.c
+++ b/block/vhdx.c
@@ -1175,7 +1175,7 @@ static int vhdx_allocate_block(BlockDriverState *bs, BDRVVHDXState *s,
     *new_offset = current_len;
 
     /* per the spec, the address for a block is in units of 1MB */
-    *new_offset = ROUND_UP(*new_offset, 1024 * 1024);
+    *new_offset = ROUND_UP(*new_offset, 1 * MiB);
     if (*new_offset > INT64_MAX) {
         return -EINVAL;
     }
@@ -1338,7 +1338,7 @@ static coroutine_fn int vhdx_co_writev(BlockDriverState *bs, int64_t sector_num,
             case PAYLOAD_BLOCK_FULLY_PRESENT:
                 /* if the file offset address is in the header zone,
                  * there is a problem */
-                if (sinfo.file_offset < (1024 * 1024)) {
+                if (sinfo.file_offset < (1 * MiB)) {
                     ret = -EFAULT;
                     goto error_bat_restore;
                 }
@@ -1889,7 +1889,8 @@ static int coroutine_fn vhdx_co_create(BlockdevCreateOptions *opts,
         return -EINVAL;
     }
     if (block_size > VHDX_BLOCK_SIZE_MAX) {
-        error_setg(errp, "Block size must not exceed %d", VHDX_BLOCK_SIZE_MAX);
+        error_setg(errp, "Block size must not exceed %" PRId64,
+                   VHDX_BLOCK_SIZE_MAX);
         return -EINVAL;
     }
 
diff --git a/block/vhdx.h b/block/vhdx.h
index 1bfb4e4f73..0b74924cee 100644
--- a/block/vhdx.h
+++ b/block/vhdx.h
@@ -17,13 +17,11 @@
 
 #ifndef BLOCK_VHDX_H
 #define BLOCK_VHDX_H
-
-#define KiB              (1 * 1024)
-#define MiB            (KiB * 1024)
-#define GiB            (MiB * 1024)
-#define TiB ((uint64_t) GiB * 1024)
+#include "qemu/units.h"
 
 #define DEFAULT_LOG_SIZE 1048576 /* 1MiB */
+/* Note: can't use 1 * MiB, because it's passed to stringify() */
+
 /* Structures and fields present in the VHDX file */
 
 /* The header section has the following blocks,
@@ -36,7 +34,7 @@
  * 0.........64KB...........128KB........192KB..........256KB................1MB
  */
 
-#define VHDX_HEADER_BLOCK_SIZE      (64 * 1024)
+#define VHDX_HEADER_BLOCK_SIZE      (64 * KiB)
 
 #define VHDX_FILE_ID_OFFSET         0
 #define VHDX_HEADER1_OFFSET         (VHDX_HEADER_BLOCK_SIZE * 1)
@@ -85,7 +83,7 @@ typedef struct QEMU_PACKED MSGUID {
 #define guid_eq(a, b) \
     (memcmp(&(a), &(b), sizeof(MSGUID)) == 0)
 
-#define VHDX_HEADER_SIZE (4 * 1024)   /* although the vhdx_header struct in disk
+#define VHDX_HEADER_SIZE (4 * KiB)    /* although the vhdx_header struct in disk
                                          is only 582 bytes, for purposes of crc
                                          the header is the first 4KB of the 64KB
                                          block */
@@ -161,8 +159,8 @@ typedef struct QEMU_PACKED VHDXRegionTableEntry {
 
 
 /* ---- LOG ENTRY STRUCTURES ---- */
-#define VHDX_LOG_MIN_SIZE (1024 * 1024)
-#define VHDX_LOG_SECTOR_SIZE 4096
+#define VHDX_LOG_MIN_SIZE (1 * MiB)
+#define VHDX_LOG_SECTOR_SIZE (4 * KiB)
 #define VHDX_LOG_HDR_SIZE 64
 #define VHDX_LOG_SIGNATURE 0x65676f6c
 typedef struct QEMU_PACKED VHDXLogEntryHeader {
diff --git a/block/vmdk.c b/block/vmdk.c
index 8dec6ef767..de8cb859f8 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -397,6 +397,8 @@ static int vmdk_parent_open(BlockDriverState *bs)
         pstrcpy(bs->auto_backing_file, end_name - p_name + 1, p_name);
         pstrcpy(bs->backing_file, sizeof(bs->backing_file),
                 bs->auto_backing_file);
+        pstrcpy(bs->backing_format, sizeof(bs->backing_format),
+                "vmdk");
     }
 
 out:
diff --git a/block/vpc.c b/block/vpc.c
index a902a4c54d..0c279b87c8 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -639,8 +639,10 @@ vpc_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
             qemu_iovec_reset(&local_qiov);
             qemu_iovec_concat(&local_qiov, qiov, bytes_done, n_bytes);
 
+            qemu_co_mutex_unlock(&s->lock);
             ret = bdrv_co_preadv(bs->file, image_offset, n_bytes,
                                  &local_qiov, 0);
+            qemu_co_mutex_lock(&s->lock);
             if (ret < 0) {
                 goto fail;
             }
@@ -697,8 +699,10 @@ vpc_co_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
         qemu_iovec_reset(&local_qiov);
         qemu_iovec_concat(&local_qiov, qiov, bytes_done, n_bytes);
 
+        qemu_co_mutex_unlock(&s->lock);
         ret = bdrv_co_pwritev(bs->file, image_offset, n_bytes,
                               &local_qiov, 0);
+        qemu_co_mutex_lock(&s->lock);
         if (ret < 0) {
             goto fail;
         }
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 01e855a066..94d45c9708 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -925,6 +925,22 @@ int coroutine_fn bdrv_co_pwritev(BdrvChild *child,
     int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
     BdrvRequestFlags flags);
 
+static inline int coroutine_fn bdrv_co_pread(BdrvChild *child,
+    int64_t offset, unsigned int bytes, void *buf, BdrvRequestFlags flags)
+{
+    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
+
+    return bdrv_co_preadv(child, offset, bytes, &qiov, flags);
+}
+
+static inline int coroutine_fn bdrv_co_pwrite(BdrvChild *child,
+    int64_t offset, unsigned int bytes, void *buf, BdrvRequestFlags flags)
+{
+    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
+
+    return bdrv_co_pwritev(child, offset, bytes, &qiov, flags);
+}
+
 extern unsigned int bdrv_drain_all_count;
 void bdrv_apply_subtree_drain(BdrvChild *child, BlockDriverState *new_parent);
 void bdrv_unapply_subtree_drain(BdrvChild *child, BlockDriverState *old_parent);
diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index 3be05c2d68..5be6224226 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -124,6 +124,25 @@ int coroutine_fn blk_co_preadv(BlockBackend *blk, int64_t offset,
 int coroutine_fn blk_co_pwritev(BlockBackend *blk, int64_t offset,
                                unsigned int bytes, QEMUIOVector *qiov,
                                BdrvRequestFlags flags);
+
+static inline int coroutine_fn blk_co_pread(BlockBackend *blk, int64_t offset,
+                                            unsigned int bytes, void *buf,
+                                            BdrvRequestFlags flags)
+{
+    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
+
+    return blk_co_preadv(blk, offset, bytes, &qiov, flags);
+}
+
+static inline int coroutine_fn blk_co_pwrite(BlockBackend *blk, int64_t offset,
+                                             unsigned int bytes, void *buf,
+                                             BdrvRequestFlags flags)
+{
+    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
+
+    return blk_co_pwritev(blk, offset, bytes, &qiov, flags);
+}
+
 int blk_pwrite_zeroes(BlockBackend *blk, int64_t offset,
                       int bytes, BdrvRequestFlags flags);
 BlockAIOCB *blk_aio_pwrite_zeroes(BlockBackend *blk, int64_t offset,
diff --git a/qemu-img.c b/qemu-img.c
index d7fe546b85..e6ad5978e0 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -267,9 +267,20 @@ static int print_block_option_help(const char *filename, const char *fmt)
         create_opts = qemu_opts_append(create_opts, proto_drv->create_opts);
     }
 
-    printf("Supported options:\n");
+    if (filename) {
+        printf("Supported options:\n");
+    } else {
+        printf("Supported %s options:\n", fmt);
+    }
     qemu_opts_print_help(create_opts, false);
     qemu_opts_free(create_opts);
+
+    if (!filename) {
+        printf("\n"
+               "The protocol level may support further options.\n"
+               "Specify the target filename to include those options.\n");
+    }
+
     return 0;
 }
 
@@ -1669,7 +1680,6 @@ static int coroutine_fn convert_co_read(ImgConvertState *s, int64_t sector_num,
                                         int nb_sectors, uint8_t *buf)
 {
     int n, ret;
-    QEMUIOVector qiov;
 
     assert(nb_sectors <= s->buf_sectors);
     while (nb_sectors > 0) {
@@ -1685,11 +1695,10 @@ static int coroutine_fn convert_co_read(ImgConvertState *s, int64_t sector_num,
         bs_sectors = s->src_sectors[src_cur];
 
         n = MIN(nb_sectors, bs_sectors - (sector_num - src_cur_offset));
-        qemu_iovec_init_buf(&qiov, buf, n << BDRV_SECTOR_BITS);
 
-        ret = blk_co_preadv(
+        ret = blk_co_pread(
                 blk, (sector_num - src_cur_offset) << BDRV_SECTOR_BITS,
-                n << BDRV_SECTOR_BITS, &qiov, 0);
+                n << BDRV_SECTOR_BITS, buf, 0);
         if (ret < 0) {
             return ret;
         }
@@ -1708,7 +1717,6 @@ static int coroutine_fn convert_co_write(ImgConvertState *s, int64_t sector_num,
                                          enum ImgConvertBlockStatus status)
 {
     int ret;
-    QEMUIOVector qiov;
 
     while (nb_sectors > 0) {
         int n = nb_sectors;
@@ -1736,10 +1744,8 @@ static int coroutine_fn convert_co_write(ImgConvertState *s, int64_t sector_num,
                 (s->compressed &&
                  !buffer_is_zero(buf, n * BDRV_SECTOR_SIZE)))
             {
-                qemu_iovec_init_buf(&qiov, buf, n << BDRV_SECTOR_BITS);
-
-                ret = blk_co_pwritev(s->target, sector_num << BDRV_SECTOR_BITS,
-                                     n << BDRV_SECTOR_BITS, &qiov, flags);
+                ret = blk_co_pwrite(s->target, sector_num << BDRV_SECTOR_BITS,
+                                    n << BDRV_SECTOR_BITS, buf, flags);
                 if (ret < 0) {
                     return ret;
                 }
diff --git a/tests/qemu-iotests/026.out b/tests/qemu-iotests/026.out
index dd10a82b51..fb89b8480c 100644
--- a/tests/qemu-iotests/026.out
+++ b/tests/qemu-iotests/026.out
@@ -14,8 +14,8 @@ No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: l1_update; errno: 5; imm: off; once: off; write
-Failed to flush the L2 table cache: Input/output error
-Failed to flush the refcount block cache: Input/output error
+qemu-io: Failed to flush the L2 table cache: Input/output error
+qemu-io: Failed to flush the refcount block cache: Input/output error
 write failed: Input/output error
 
 1 leaked clusters were found on the image.
@@ -23,8 +23,8 @@ This means waste of disk space, but no harm to data.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: l1_update; errno: 5; imm: off; once: off; write -b
-Failed to flush the L2 table cache: Input/output error
-Failed to flush the refcount block cache: Input/output error
+qemu-io: Failed to flush the L2 table cache: Input/output error
+qemu-io: Failed to flush the refcount block cache: Input/output error
 write failed: Input/output error
 
 1 leaked clusters were found on the image.
@@ -42,8 +42,8 @@ No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: l1_update; errno: 28; imm: off; once: off; write
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 
 1 leaked clusters were found on the image.
@@ -51,8 +51,8 @@ This means waste of disk space, but no harm to data.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: l1_update; errno: 28; imm: off; once: off; write -b
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 
 1 leaked clusters were found on the image.
@@ -134,8 +134,8 @@ No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: l2_update; errno: 5; imm: off; once: off; write
-Failed to flush the L2 table cache: Input/output error
-Failed to flush the refcount block cache: Input/output error
+qemu-io: Failed to flush the L2 table cache: Input/output error
+qemu-io: Failed to flush the refcount block cache: Input/output error
 write failed: Input/output error
 
 127 leaked clusters were found on the image.
@@ -143,8 +143,8 @@ This means waste of disk space, but no harm to data.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: l2_update; errno: 5; imm: off; once: off; write -b
-Failed to flush the L2 table cache: Input/output error
-Failed to flush the refcount block cache: Input/output error
+qemu-io: Failed to flush the L2 table cache: Input/output error
+qemu-io: Failed to flush the refcount block cache: Input/output error
 write failed: Input/output error
 
 127 leaked clusters were found on the image.
@@ -162,8 +162,8 @@ No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: l2_update; errno: 28; imm: off; once: off; write
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 
 127 leaked clusters were found on the image.
@@ -171,8 +171,8 @@ This means waste of disk space, but no harm to data.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: l2_update; errno: 28; imm: off; once: off; write -b
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 
 127 leaked clusters were found on the image.
@@ -190,15 +190,15 @@ No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: l2_alloc_write; errno: 5; imm: off; once: off; write
-Failed to flush the L2 table cache: Input/output error
-Failed to flush the refcount block cache: Input/output error
+qemu-io: Failed to flush the L2 table cache: Input/output error
+qemu-io: Failed to flush the refcount block cache: Input/output error
 write failed: Input/output error
 No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: l2_alloc_write; errno: 5; imm: off; once: off; write -b
-Failed to flush the L2 table cache: Input/output error
-Failed to flush the refcount block cache: Input/output error
+qemu-io: Failed to flush the L2 table cache: Input/output error
+qemu-io: Failed to flush the refcount block cache: Input/output error
 write failed: Input/output error
 
 1 leaked clusters were found on the image.
@@ -216,15 +216,15 @@ No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: l2_alloc_write; errno: 28; imm: off; once: off; write
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: l2_alloc_write; errno: 28; imm: off; once: off; write -b
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 
 1 leaked clusters were found on the image.
@@ -242,15 +242,15 @@ No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: write_aio; errno: 5; imm: off; once: off; write
-Failed to flush the L2 table cache: Input/output error
-Failed to flush the refcount block cache: Input/output error
+qemu-io: Failed to flush the L2 table cache: Input/output error
+qemu-io: Failed to flush the refcount block cache: Input/output error
 write failed: Input/output error
 No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: write_aio; errno: 5; imm: off; once: off; write -b
-Failed to flush the L2 table cache: Input/output error
-Failed to flush the refcount block cache: Input/output error
+qemu-io: Failed to flush the L2 table cache: Input/output error
+qemu-io: Failed to flush the refcount block cache: Input/output error
 write failed: Input/output error
 No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
@@ -266,15 +266,15 @@ No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: write_aio; errno: 28; imm: off; once: off; write
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: write_aio; errno: 28; imm: off; once: off; write -b
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
@@ -290,15 +290,15 @@ No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: refblock_load; errno: 5; imm: off; once: off; write
-Failed to flush the L2 table cache: Input/output error
-Failed to flush the refcount block cache: Input/output error
+qemu-io: Failed to flush the L2 table cache: Input/output error
+qemu-io: Failed to flush the refcount block cache: Input/output error
 write failed: Input/output error
 No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: refblock_load; errno: 5; imm: off; once: off; write -b
-Failed to flush the L2 table cache: Input/output error
-Failed to flush the refcount block cache: Input/output error
+qemu-io: Failed to flush the L2 table cache: Input/output error
+qemu-io: Failed to flush the refcount block cache: Input/output error
 write failed: Input/output error
 No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
@@ -314,15 +314,15 @@ No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: refblock_load; errno: 28; imm: off; once: off; write
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: refblock_load; errno: 28; imm: off; once: off; write -b
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
@@ -338,15 +338,15 @@ No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: refblock_update_part; errno: 5; imm: off; once: off; write
-Failed to flush the L2 table cache: Input/output error
-Failed to flush the refcount block cache: Input/output error
+qemu-io: Failed to flush the L2 table cache: Input/output error
+qemu-io: Failed to flush the refcount block cache: Input/output error
 write failed: Input/output error
 No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: refblock_update_part; errno: 5; imm: off; once: off; write -b
-Failed to flush the L2 table cache: Input/output error
-Failed to flush the refcount block cache: Input/output error
+qemu-io: Failed to flush the L2 table cache: Input/output error
+qemu-io: Failed to flush the refcount block cache: Input/output error
 write failed: Input/output error
 No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
@@ -362,15 +362,15 @@ No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: refblock_update_part; errno: 28; imm: off; once: off; write
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: refblock_update_part; errno: 28; imm: off; once: off; write -b
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
@@ -386,15 +386,15 @@ No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: refblock_alloc; errno: 5; imm: off; once: off; write
-Failed to flush the L2 table cache: Input/output error
-Failed to flush the refcount block cache: Input/output error
+qemu-io: Failed to flush the L2 table cache: Input/output error
+qemu-io: Failed to flush the refcount block cache: Input/output error
 write failed: Input/output error
 No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: refblock_alloc; errno: 5; imm: off; once: off; write -b
-Failed to flush the L2 table cache: Input/output error
-Failed to flush the refcount block cache: Input/output error
+qemu-io: Failed to flush the L2 table cache: Input/output error
+qemu-io: Failed to flush the refcount block cache: Input/output error
 write failed: Input/output error
 No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
@@ -410,15 +410,15 @@ No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: refblock_alloc; errno: 28; imm: off; once: off; write
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: refblock_alloc; errno: 28; imm: off; once: off; write -b
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
@@ -477,8 +477,8 @@ No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: refblock_alloc_hookup; errno: 28; imm: off; once: off; write
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 
 55 leaked clusters were found on the image.
@@ -486,8 +486,8 @@ This means waste of disk space, but no harm to data.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: refblock_alloc_hookup; errno: 28; imm: off; once: off; write -b
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 
 251 leaked clusters were found on the image.
@@ -505,15 +505,15 @@ No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: refblock_alloc_write; errno: 28; imm: off; once: off; write
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: refblock_alloc_write; errno: 28; imm: off; once: off; write -b
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
@@ -529,8 +529,8 @@ No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: refblock_alloc_write_blocks; errno: 28; imm: off; once: off; write
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 
 10 leaked clusters were found on the image.
@@ -538,8 +538,8 @@ This means waste of disk space, but no harm to data.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: refblock_alloc_write_blocks; errno: 28; imm: off; once: off; write -b
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 
 23 leaked clusters were found on the image.
@@ -557,8 +557,8 @@ No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: refblock_alloc_write_table; errno: 28; imm: off; once: off; write
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 
 10 leaked clusters were found on the image.
@@ -566,8 +566,8 @@ This means waste of disk space, but no harm to data.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: refblock_alloc_write_table; errno: 28; imm: off; once: off; write -b
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 
 23 leaked clusters were found on the image.
@@ -585,8 +585,8 @@ No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: refblock_alloc_switch_table; errno: 28; imm: off; once: off; write
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 
 10 leaked clusters were found on the image.
@@ -594,8 +594,8 @@ This means waste of disk space, but no harm to data.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: refblock_alloc_switch_table; errno: 28; imm: off; once: off; write -b
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 
 23 leaked clusters were found on the image.
@@ -631,8 +631,8 @@ No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: l1_grow_write_table; errno: 5; imm: off; once: off
-Failed to flush the L2 table cache: Input/output error
-Failed to flush the refcount block cache: Input/output error
+qemu-io: Failed to flush the L2 table cache: Input/output error
+qemu-io: Failed to flush the refcount block cache: Input/output error
 write failed: Input/output error
 No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
@@ -643,8 +643,8 @@ No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: l1_grow_write_table; errno: 28; imm: off; once: off
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
@@ -655,8 +655,8 @@ No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: l1_grow_activate_table; errno: 5; imm: off; once: off
-Failed to flush the L2 table cache: Input/output error
-Failed to flush the refcount block cache: Input/output error
+qemu-io: Failed to flush the L2 table cache: Input/output error
+qemu-io: Failed to flush the refcount block cache: Input/output error
 write failed: Input/output error
 
 96 leaked clusters were found on the image.
@@ -669,8 +669,8 @@ No errors were found on the image.
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
 
 Event: l1_grow_activate_table; errno: 28; imm: off; once: off
-Failed to flush the L2 table cache: No space left on device
-Failed to flush the refcount block cache: No space left on device
+qemu-io: Failed to flush the L2 table cache: No space left on device
+qemu-io: Failed to flush the refcount block cache: No space left on device
 write failed: No space left on device
 
 96 leaked clusters were found on the image.
diff --git a/tests/qemu-iotests/043.out b/tests/qemu-iotests/043.out
index b37d2a3807..0280f999ce 100644
--- a/tests/qemu-iotests/043.out
+++ b/tests/qemu-iotests/043.out
@@ -22,19 +22,19 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728 backing_file=TEST_DIR/
 == finite chain of length 3 (human) ==
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 128M (134217728 bytes)
+virtual size: 128 MiB (134217728 bytes)
 cluster_size: 65536
 backing file: TEST_DIR/t.IMGFMT.2.base
 
 image: TEST_DIR/t.IMGFMT.2.base
 file format: IMGFMT
-virtual size: 128M (134217728 bytes)
+virtual size: 128 MiB (134217728 bytes)
 cluster_size: 65536
 backing file: TEST_DIR/t.IMGFMT.1.base
 
 image: TEST_DIR/t.IMGFMT.1.base
 file format: IMGFMT
-virtual size: 128M (134217728 bytes)
+virtual size: 128 MiB (134217728 bytes)
 cluster_size: 65536
 
 == finite chain of length 3 (json) ==
diff --git a/tests/qemu-iotests/053.out b/tests/qemu-iotests/053.out
index 8e793b6462..8a65881232 100644
--- a/tests/qemu-iotests/053.out
+++ b/tests/qemu-iotests/053.out
@@ -9,7 +9,7 @@ wrote 512/512 bytes at offset 0
 No errors were found on the image.
 
 == Checking compressed image virtual disk size ==
-virtual size: 512 (512 bytes)
+virtual size: 512 B (512 bytes)
 
 == Verifying the compressed image ==
 read 512/512 bytes at offset 0
diff --git a/tests/qemu-iotests/059.out b/tests/qemu-iotests/059.out
index f6dce7947c..700ad1f290 100644
--- a/tests/qemu-iotests/059.out
+++ b/tests/qemu-iotests/059.out
@@ -16,7 +16,7 @@ can't open device TEST_DIR/t.vmdk: L1 size too big
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=2147483648 subformat=monolithicFlat
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 2.0G (2147483648 bytes)
+virtual size: 2 GiB (2147483648 bytes)
 
 === Testing monolithicFlat with zeroed_grain ===
 qemu-img: TEST_DIR/t.IMGFMT: Flat image can't enable zeroed grain
@@ -26,8 +26,8 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=2147483648 subformat=monolithicF
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824000 subformat=twoGbMaxExtentFlat
 image: TEST_DIR/t.vmdk
 file format: vmdk
-virtual size: 1.0T (1073741824000 bytes)
-disk size: 16K
+virtual size: 0.977 TiB (1073741824000 bytes)
+disk size: 16 KiB
 Format specific information:
     cid: XXXXXXXX
     parent cid: XXXXXXXX
@@ -2055,7 +2055,7 @@ can't open: Cannot use relative extent paths with VMDK descriptor file 'json:{"i
 === Testing version 3 ===
 image: TEST_DIR/iotest-version3.IMGFMT
 file format: IMGFMT
-virtual size: 16G (17179869184 bytes)
+virtual size: 16 GiB (17179869184 bytes)
 cluster_size: 65536
 read 512/512 bytes at offset 0
 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
@@ -2262,7 +2262,7 @@ read 512/512 bytes at offset 64931328
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=4398046511104 subformat=monolithicFlat
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 4.0T (4398046511104 bytes)
+virtual size: 4 TiB (4398046511104 bytes)
 wrote 512/512 bytes at offset 966367641600
 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 e100000000:  0a 0a 0a 0a 0a 0a 0a 0a 0a 0a 0a 0a 0a 0a 0a 0a  ................
diff --git a/tests/qemu-iotests/060.out b/tests/qemu-iotests/060.out
index af623cfd86..e42bf8c5a9 100644
--- a/tests/qemu-iotests/060.out
+++ b/tests/qemu-iotests/060.out
@@ -13,14 +13,14 @@ write failed: Input/output error
 incompatible_features     0x2
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 cluster_size: 65536
 Format specific information:
     compat: 1.1
     lazy refcounts: false
     refcount bits: 16
     corrupt: true
-can't open device TEST_DIR/t.IMGFMT: IMGFMT: Image is corrupt; cannot be opened read/write
+qemu-io: can't open device TEST_DIR/t.IMGFMT: IMGFMT: Image is corrupt; cannot be opened read/write
 no file open, try 'help open'
 read 512/512 bytes at offset 0
 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
@@ -267,7 +267,7 @@ No errors were found on the image.
 === Testing zero refcount table size ===
 
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
-can't open device TEST_DIR/t.IMGFMT: Image does not contain a reference count table
+qemu-io: can't open device TEST_DIR/t.IMGFMT: Image does not contain a reference count table
 ERROR cluster 0 refcount=0 reference=1
 ERROR cluster 3 refcount=0 reference=1
 Rebuilding refcount structure
@@ -296,7 +296,7 @@ Can't get refcount for cluster 2: Input/output error
 Can't get refcount for cluster 3: Input/output error
 Rebuilding refcount structure
 Repairing cluster 1 refcount=1 reference=0
-can't open device TEST_DIR/t.IMGFMT: Could not repair dirty image: Input/output error
+qemu-io: can't open device TEST_DIR/t.IMGFMT: Could not repair dirty image: Input/output error
 --- Repairing ---
 Leaked cluster 1 refcount=1 reference=0
 Repairing cluster 1 refcount=1 reference=0
@@ -364,10 +364,10 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
 qcow2: Marking image as corrupt: Refblock at 0xffffff00000000 is not covered by the refcount structures; further corruption events will be suppressed
 qemu-img: Failed to discard unused refblocks: Input/output error
 --- Checking and retrying ---
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 No errors were found on the image.
 Image resized.
-virtual size: 32M (33554432 bytes)
+virtual size: 32 MiB (33554432 bytes)
 
 === Discarding a non-covered in-bounds refblock ===
 
@@ -375,10 +375,10 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
 qcow2: Marking image as corrupt: Refblock at 0x1000000000 is not covered by the refcount structures; further corruption events will be suppressed
 qemu-img: Failed to discard unused refblocks: Input/output error
 --- Checking and retrying ---
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 No errors were found on the image.
 Image resized.
-virtual size: 32M (33554432 bytes)
+virtual size: 32 MiB (33554432 bytes)
 
 === Discarding a refblock covered by an unaligned refblock ===
 
diff --git a/tests/qemu-iotests/061.out b/tests/qemu-iotests/061.out
index 9fe1ec702f..1aa7d37ff9 100644
--- a/tests/qemu-iotests/061.out
+++ b/tests/qemu-iotests/061.out
@@ -495,7 +495,7 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 data_file=TEST_DIR/t.IM
 qemu-img: Cannot downgrade an image with a data file
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 cluster_size: 65536
 Format specific information:
     compat: 1.1
@@ -515,7 +515,7 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 data_file=TEST_DIR/t.IM
 qemu-img: Could not open 'TEST_DIR/t.IMGFMT': Could not open 'foo': No such file or directory
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 cluster_size: 65536
 Format specific information:
     compat: 1.1
@@ -528,7 +528,7 @@ Format specific information:
 qemu-img: Could not open 'TEST_DIR/t.IMGFMT': 'data-file' is required for this image
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 cluster_size: 65536
 Format specific information:
     compat: 1.1
@@ -542,7 +542,7 @@ Format specific information:
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 data_file=TEST_DIR/t.IMGFMT.data data_file_raw=on
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 cluster_size: 65536
 Format specific information:
     compat: 1.1
@@ -554,7 +554,7 @@ Format specific information:
 No errors were found on the image.
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 cluster_size: 65536
 Format specific information:
     compat: 1.1
@@ -567,7 +567,7 @@ No errors were found on the image.
 qemu-img: data-file-raw cannot be set on existing images
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 cluster_size: 65536
 Format specific information:
     compat: 1.1
diff --git a/tests/qemu-iotests/069.out b/tests/qemu-iotests/069.out
index f97585677b..c78e8c2b72 100644
--- a/tests/qemu-iotests/069.out
+++ b/tests/qemu-iotests/069.out
@@ -4,5 +4,5 @@ QA output created by 069
 
 Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=131072
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=131072 backing_file=TEST_DIR/t.IMGFMT.base
-can't open device TEST_DIR/t.IMGFMT: Could not open backing file: Could not open 'TEST_DIR/t.IMGFMT.base': No such file or directory
+qemu-io: can't open device TEST_DIR/t.IMGFMT: Could not open backing file: Could not open 'TEST_DIR/t.IMGFMT.base': No such file or directory
 *** done
diff --git a/tests/qemu-iotests/070.out b/tests/qemu-iotests/070.out
index c269d99483..2fbfd7eaf3 100644
--- a/tests/qemu-iotests/070.out
+++ b/tests/qemu-iotests/070.out
@@ -1,7 +1,7 @@
 QA output created by 070
 
 === Verify open image read-only fails, due to dirty log ===
-can't open device TEST_DIR/iotest-dirtylog-10G-4M.vhdx: VHDX image file 'TEST_DIR/iotest-dirtylog-10G-4M.vhdx' opened read-only, but contains a log that needs to be replayed
+qemu-io: can't open device TEST_DIR/iotest-dirtylog-10G-4M.vhdx: VHDX image file 'TEST_DIR/iotest-dirtylog-10G-4M.vhdx' opened read-only, but contains a log that needs to be replayed
 To replay the log, run:
 qemu-img check -r all 'TEST_DIR/iotest-dirtylog-10G-4M.vhdx'
 === Verify open image replays log  ===
@@ -22,6 +22,6 @@ read 18874368/18874368 bytes at offset 0
 === Verify image created by Disk2VHD can be opened ===
 image: TEST_DIR/test-disk2vhd.IMGFMT
 file format: IMGFMT
-virtual size: 256M (268435456 bytes)
+virtual size: 256 MiB (268435456 bytes)
 cluster_size: 2097152
 *** done
diff --git a/tests/qemu-iotests/075.out b/tests/qemu-iotests/075.out
index b234b758e0..4f3871d337 100644
--- a/tests/qemu-iotests/075.out
+++ b/tests/qemu-iotests/075.out
@@ -9,23 +9,23 @@ read 512/512 bytes at offset 1048064
 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 
 == block_size must be a multiple of 512 ==
-can't open device TEST_DIR/simple-pattern.cloop: block_size 513 must be a multiple of 512
+qemu-io: can't open device TEST_DIR/simple-pattern.cloop: block_size 513 must be a multiple of 512
 
 == block_size cannot be zero ==
-can't open device TEST_DIR/simple-pattern.cloop: block_size cannot be zero
+qemu-io: can't open device TEST_DIR/simple-pattern.cloop: block_size cannot be zero
 
 == huge block_size ===
-can't open device TEST_DIR/simple-pattern.cloop: block_size 4294966784 must be 64 MB or less
+qemu-io: can't open device TEST_DIR/simple-pattern.cloop: block_size 4294966784 must be 64 MB or less
 
 == offsets_size overflow ===
-can't open device TEST_DIR/simple-pattern.cloop: n_blocks 4294967295 must be 536870911 or less
+qemu-io: can't open device TEST_DIR/simple-pattern.cloop: n_blocks 4294967295 must be 536870911 or less
 
 == refuse images that require too many offsets ===
-can't open device TEST_DIR/simple-pattern.cloop: image requires too many offsets, try increasing block size
+qemu-io: can't open device TEST_DIR/simple-pattern.cloop: image requires too many offsets, try increasing block size
 
 == refuse images with non-monotonically increasing offsets ==
-can't open device TEST_DIR/simple-pattern.cloop: offsets not monotonically increasing at index 1, image file is corrupt
+qemu-io: can't open device TEST_DIR/simple-pattern.cloop: offsets not monotonically increasing at index 1, image file is corrupt
 
 == refuse images with invalid compressed block size ==
-can't open device TEST_DIR/simple-pattern.cloop: invalid compressed block size at index 1, image file is corrupt
+qemu-io: can't open device TEST_DIR/simple-pattern.cloop: invalid compressed block size at index 1, image file is corrupt
 *** done
diff --git a/tests/qemu-iotests/076.out b/tests/qemu-iotests/076.out
index 9c66c5fb46..2de8a710a5 100644
--- a/tests/qemu-iotests/076.out
+++ b/tests/qemu-iotests/076.out
@@ -5,13 +5,13 @@ read 65536/65536 bytes at offset 0
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 
 == Negative catalog size ==
-can't open device TEST_DIR/parallels-v1: Catalog too large
+qemu-io: can't open device TEST_DIR/parallels-v1: Catalog too large
 
 == Overflow in catalog allocation ==
-can't open device TEST_DIR/parallels-v1: Catalog too large
+qemu-io: can't open device TEST_DIR/parallels-v1: Catalog too large
 
 == Zero sectors per track ==
-can't open device TEST_DIR/parallels-v1: Invalid image: Zero sectors per track
+qemu-io: can't open device TEST_DIR/parallels-v1: Invalid image: Zero sectors per track
 
 == Read from a valid v2 image ==
 read 65536/65536 bytes at offset 0
diff --git a/tests/qemu-iotests/078.out b/tests/qemu-iotests/078.out
index c3d6aa4fe4..4a82e1779f 100644
--- a/tests/qemu-iotests/078.out
+++ b/tests/qemu-iotests/078.out
@@ -5,18 +5,18 @@ read 512/512 bytes at offset 0
 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 
 == Negative catalog size ==
-can't open device TEST_DIR/empty.bochs: Catalog size is too large
+qemu-io: can't open device TEST_DIR/empty.bochs: Catalog size is too large
 
 == Overflow for catalog size * sizeof(uint32_t) ==
-can't open device TEST_DIR/empty.bochs: Catalog size is too large
+qemu-io: can't open device TEST_DIR/empty.bochs: Catalog size is too large
 
 == Too small catalog bitmap for image size ==
-can't open device TEST_DIR/empty.bochs: Catalog size is too small for this disk size
-can't open device TEST_DIR/empty.bochs: Catalog size is too small for this disk size
+qemu-io: can't open device TEST_DIR/empty.bochs: Catalog size is too small for this disk size
+qemu-io: can't open device TEST_DIR/empty.bochs: Catalog size is too small for this disk size
 
 == Negative extent size ==
-can't open device TEST_DIR/empty.bochs: Extent size 2147483648 is too large
+qemu-io: can't open device TEST_DIR/empty.bochs: Extent size 2147483648 is too large
 
 == Zero extent size ==
-can't open device TEST_DIR/empty.bochs: Extent size must be at least 512
+qemu-io: can't open device TEST_DIR/empty.bochs: Extent size must be at least 512
 *** done
diff --git a/tests/qemu-iotests/080.out b/tests/qemu-iotests/080.out
index 281c7e0d1d..45ab01db8e 100644
--- a/tests/qemu-iotests/080.out
+++ b/tests/qemu-iotests/080.out
@@ -2,34 +2,34 @@ QA output created by 080
 
 == Huge header size ==
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
-can't open device TEST_DIR/t.qcow2: qcow2 header exceeds cluster size
-can't open device TEST_DIR/t.qcow2: qcow2 header exceeds cluster size
+qemu-io: can't open device TEST_DIR/t.qcow2: qcow2 header exceeds cluster size
+qemu-io: can't open device TEST_DIR/t.qcow2: qcow2 header exceeds cluster size
 
 == Huge unknown header extension ==
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
-can't open device TEST_DIR/t.qcow2: Invalid backing file offset
-can't open device TEST_DIR/t.qcow2: Header extension too large
-can't open device TEST_DIR/t.qcow2: Header extension too large
+qemu-io: can't open device TEST_DIR/t.qcow2: Invalid backing file offset
+qemu-io: can't open device TEST_DIR/t.qcow2: Header extension too large
+qemu-io: can't open device TEST_DIR/t.qcow2: Header extension too large
 
 == Huge refcount table size ==
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
-can't open device TEST_DIR/t.qcow2: Reference count table too large
-can't open device TEST_DIR/t.qcow2: Reference count table too large
+qemu-io: can't open device TEST_DIR/t.qcow2: Reference count table too large
+qemu-io: can't open device TEST_DIR/t.qcow2: Reference count table too large
 
 == Misaligned refcount table ==
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
-can't open device TEST_DIR/t.qcow2: Reference count table offset invalid
+qemu-io: can't open device TEST_DIR/t.qcow2: Reference count table offset invalid
 
 == Huge refcount offset ==
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
-can't open device TEST_DIR/t.qcow2: Reference count table offset invalid
+qemu-io: can't open device TEST_DIR/t.qcow2: Reference count table offset invalid
 
 == Invalid snapshot table ==
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
-can't open device TEST_DIR/t.qcow2: Snapshot table too large
-can't open device TEST_DIR/t.qcow2: Snapshot table too large
-can't open device TEST_DIR/t.qcow2: Snapshot table offset invalid
-can't open device TEST_DIR/t.qcow2: Snapshot table offset invalid
+qemu-io: can't open device TEST_DIR/t.qcow2: Snapshot table too large
+qemu-io: can't open device TEST_DIR/t.qcow2: Snapshot table too large
+qemu-io: can't open device TEST_DIR/t.qcow2: Snapshot table offset invalid
+qemu-io: can't open device TEST_DIR/t.qcow2: Snapshot table offset invalid
 
 == Hitting snapshot table size limit ==
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
@@ -39,10 +39,10 @@ read 512/512 bytes at offset 0
 
 == Invalid L1 table ==
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
-can't open device TEST_DIR/t.qcow2: Active L1 table too large
-can't open device TEST_DIR/t.qcow2: Active L1 table too large
-can't open device TEST_DIR/t.qcow2: Active L1 table offset invalid
-can't open device TEST_DIR/t.qcow2: Active L1 table offset invalid
+qemu-io: can't open device TEST_DIR/t.qcow2: Active L1 table too large
+qemu-io: can't open device TEST_DIR/t.qcow2: Active L1 table too large
+qemu-io: can't open device TEST_DIR/t.qcow2: Active L1 table offset invalid
+qemu-io: can't open device TEST_DIR/t.qcow2: Active L1 table offset invalid
 
 == Invalid L1 table (with internal snapshot in the image) ==
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
@@ -50,7 +50,7 @@ qemu-img: Could not open 'TEST_DIR/t.IMGFMT': L1 table is too small
 
 == Invalid backing file size ==
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
-can't open device TEST_DIR/t.qcow2: Backing file name too long
+qemu-io: can't open device TEST_DIR/t.qcow2: Backing file name too long
 
 == Invalid L2 entry (huge physical offset) ==
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
@@ -66,7 +66,7 @@ wrote 512/512 bytes at offset 0
 qemu-img: Failed to load snapshot: Snapshot L1 table offset invalid
 qemu-img: Snapshot L1 table offset invalid
 qemu-img: Failed to turn zero into data clusters: Invalid argument
-Failed to flush the refcount block cache: Invalid argument
+qemu-io: Failed to flush the refcount block cache: Invalid argument
 write failed: Invalid argument
 qemu-img: Snapshot L1 table offset invalid
 qemu-img: Could not apply snapshot 'test': Failed to load snapshot: Invalid argument
@@ -89,7 +89,7 @@ wrote 512/512 bytes at offset 0
 qemu-img: Failed to load snapshot: Snapshot L1 table too large
 qemu-img: Snapshot L1 table too large
 qemu-img: Failed to turn zero into data clusters: File too large
-Failed to flush the refcount block cache: File too large
+qemu-io: Failed to flush the refcount block cache: File too large
 write failed: File too large
 qemu-img: Snapshot L1 table too large
 qemu-img: Could not apply snapshot 'test': Failed to load snapshot: File too large
diff --git a/tests/qemu-iotests/081.out b/tests/qemu-iotests/081.out
index 8ec1783ffe..04091b64e5 100644
--- a/tests/qemu-iotests/081.out
+++ b/tests/qemu-iotests/081.out
@@ -70,7 +70,7 @@ read 10485760/10485760 bytes at offset 0
 10 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 
 == checking the blkverify mode with invalid settings ==
-can't open: blkverify=on can only be set if there are exactly two files and vote-threshold is 2
+qemu-io: can't open: blkverify=on can only be set if there are exactly two files and vote-threshold is 2
 
 == dynamically adding a child to a quorum ==
 Testing:
diff --git a/tests/qemu-iotests/082 b/tests/qemu-iotests/082
index d0afa46e9a..278511dba4 100755
--- a/tests/qemu-iotests/082
+++ b/tests/qemu-iotests/082
@@ -212,7 +212,10 @@ run_qemu_img amend -f $IMGFMT -o backing_file="$TEST_IMG" -o ,, -o help "$TEST_I
 
 # Leave out everything that isn't needed
 run_qemu_img amend -f $IMGFMT -o help
-run_qemu_img convert -o help
+
+# amend requires specifying either a format explicitly, or a file
+# which it can probe
+run_qemu_img amend -o help
 
 # Try help option for a format that does not support amendment
 run_qemu_img amend -f bochs -o help
diff --git a/tests/qemu-iotests/082.out b/tests/qemu-iotests/082.out
index 915640613f..7e25706813 100644
--- a/tests/qemu-iotests/082.out
+++ b/tests/qemu-iotests/082.out
@@ -6,14 +6,14 @@ Testing: create -f foo -f qcow2 TEST_DIR/t.qcow2 128M
 Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 size=134217728 cluster_size=65536 lazy_refcounts=off refcount_bits=16
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 128M (134217728 bytes)
+virtual size: 128 MiB (134217728 bytes)
 cluster_size: 65536
 
 Testing: create -f qcow2 -o cluster_size=4k -o lazy_refcounts=on TEST_DIR/t.qcow2 128M
 Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 size=134217728 cluster_size=4096 lazy_refcounts=on refcount_bits=16
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 128M (134217728 bytes)
+virtual size: 128 MiB (134217728 bytes)
 cluster_size: 4096
 Format specific information:
     compat: 1.1
@@ -25,7 +25,7 @@ Testing: create -f qcow2 -o cluster_size=4k -o lazy_refcounts=on -o cluster_size
 Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 size=134217728 cluster_size=8192 lazy_refcounts=on refcount_bits=16
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 128M (134217728 bytes)
+virtual size: 128 MiB (134217728 bytes)
 cluster_size: 8192
 Format specific information:
     compat: 1.1
@@ -37,7 +37,7 @@ Testing: create -f qcow2 -o cluster_size=4k,cluster_size=8k TEST_DIR/t.qcow2 128
 Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 size=134217728 cluster_size=8192 lazy_refcounts=off refcount_bits=16
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 128M (134217728 bytes)
+virtual size: 128 MiB (134217728 bytes)
 cluster_size: 8192
 
 === create: help for -o ===
@@ -242,7 +242,7 @@ Testing: create -f qcow2 -o backing_file=TEST_DIR/t.qcow2 -o ,, -o help TEST_DIR
 qemu-img: Invalid option list: ,,
 
 Testing: create -f qcow2 -o help
-Supported options:
+Supported qcow2 options:
   backing_file=<str>     - File name of a base image
   backing_fmt=<str>      - Image format of the base image
   cluster_size=<size>    - qcow2 cluster size
@@ -263,10 +263,16 @@ Supported options:
   refcount_bits=<num>    - Width of a reference count entry in bits
   size=<size>            - Virtual disk size
 
+The protocol level may support further options.
+Specify the target filename to include those options.
+
 Testing: create -o help
-Supported options:
+Supported raw options:
   size=<size>            - Virtual disk size
 
+The protocol level may support further options.
+Specify the target filename to include those options.
+
 Testing: create -f bochs -o help
 qemu-img: Format driver 'bochs' does not support image creation
 
@@ -278,18 +284,18 @@ Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 size=134217728 cluster_size=65536 lazy_
 Testing: convert -f foo -f qcow2 TEST_DIR/t.qcow2 TEST_DIR/t.qcow2.base
 image: TEST_DIR/t.IMGFMT.base
 file format: raw
-virtual size: 128M (134217728 bytes)
+virtual size: 128 MiB (134217728 bytes)
 
 Testing: convert -O foo -O qcow2 TEST_DIR/t.qcow2 TEST_DIR/t.qcow2.base
 image: TEST_DIR/t.IMGFMT.base
 file format: IMGFMT
-virtual size: 128M (134217728 bytes)
+virtual size: 128 MiB (134217728 bytes)
 cluster_size: 65536
 
 Testing: convert -O qcow2 -o cluster_size=4k -o lazy_refcounts=on TEST_DIR/t.qcow2 TEST_DIR/t.qcow2.base
 image: TEST_DIR/t.IMGFMT.base
 file format: IMGFMT
-virtual size: 128M (134217728 bytes)
+virtual size: 128 MiB (134217728 bytes)
 cluster_size: 4096
 Format specific information:
     compat: 1.1
@@ -300,7 +306,7 @@ Format specific information:
 Testing: convert -O qcow2 -o cluster_size=4k -o lazy_refcounts=on -o cluster_size=8k TEST_DIR/t.qcow2 TEST_DIR/t.qcow2.base
 image: TEST_DIR/t.IMGFMT.base
 file format: IMGFMT
-virtual size: 128M (134217728 bytes)
+virtual size: 128 MiB (134217728 bytes)
 cluster_size: 8192
 Format specific information:
     compat: 1.1
@@ -311,7 +317,7 @@ Format specific information:
 Testing: convert -O qcow2 -o cluster_size=4k,cluster_size=8k TEST_DIR/t.qcow2 TEST_DIR/t.qcow2.base
 image: TEST_DIR/t.IMGFMT.base
 file format: IMGFMT
-virtual size: 128M (134217728 bytes)
+virtual size: 128 MiB (134217728 bytes)
 cluster_size: 8192
 
 === convert: help for -o ===
@@ -516,7 +522,7 @@ Testing: convert -O qcow2 -o backing_file=TEST_DIR/t.qcow2 -o ,, -o help TEST_DI
 qemu-img: Invalid option list: ,,
 
 Testing: convert -O qcow2 -o help
-Supported options:
+Supported qcow2 options:
   backing_file=<str>     - File name of a base image
   backing_fmt=<str>      - Image format of the base image
   cluster_size=<size>    - qcow2 cluster size
@@ -537,10 +543,16 @@ Supported options:
   refcount_bits=<num>    - Width of a reference count entry in bits
   size=<size>            - Virtual disk size
 
+The protocol level may support further options.
+Specify the target filename to include those options.
+
 Testing: convert -o help
-Supported options:
+Supported raw options:
   size=<size>            - Virtual disk size
 
+The protocol level may support further options.
+Specify the target filename to include those options.
+
 Testing: convert -O bochs -o help
 qemu-img: Format driver 'bochs' does not support image creation
 
@@ -560,7 +572,7 @@ qemu-img: Cannot enable copy offloading when -c is used
 Testing: amend -f foo -f qcow2 -o lazy_refcounts=on TEST_DIR/t.qcow2
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 128M (134217728 bytes)
+virtual size: 128 MiB (134217728 bytes)
 cluster_size: 65536
 Format specific information:
     compat: 1.1
@@ -571,7 +583,7 @@ Format specific information:
 Testing: amend -f qcow2 -o size=130M -o lazy_refcounts=off TEST_DIR/t.qcow2
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 130M (136314880 bytes)
+virtual size: 130 MiB (136314880 bytes)
 cluster_size: 65536
 Format specific information:
     compat: 1.1
@@ -582,7 +594,7 @@ Format specific information:
 Testing: amend -f qcow2 -o size=8M -o lazy_refcounts=on -o size=132M TEST_DIR/t.qcow2
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 132M (138412032 bytes)
+virtual size: 132 MiB (138412032 bytes)
 cluster_size: 65536
 Format specific information:
     compat: 1.1
@@ -593,7 +605,7 @@ Format specific information:
 Testing: amend -f qcow2 -o size=4M,size=148M TEST_DIR/t.qcow2
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 148M (155189248 bytes)
+virtual size: 148 MiB (155189248 bytes)
 cluster_size: 65536
 
 === amend: help for -o ===
@@ -831,9 +843,8 @@ Creation options for 'qcow2':
 
 Note that not all of these options may be amendable.
 
-Testing: convert -o help
-Supported options:
-  size=<size>            - Virtual disk size
+Testing: amend -o help
+qemu-img: Expecting one image file name
 
 Testing: amend -f bochs -o help
 qemu-img: Format driver 'bochs' does not support option amendment
diff --git a/tests/qemu-iotests/084.out b/tests/qemu-iotests/084.out
index 5c5ab928c9..c2648d963f 100644
--- a/tests/qemu-iotests/084.out
+++ b/tests/qemu-iotests/084.out
@@ -5,7 +5,7 @@ QA output created by 084
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 cluster_size: 1048576
 disk image file size in bytes: 67109888
 
@@ -14,13 +14,13 @@ disk image file size in bytes: 67109888
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 cluster_size: 1048576
 disk image file size in bytes: 1024
 Test 1: Maximum size (512 TB - 128 MB):
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 512T (562949819203584 bytes)
+virtual size: 512 TiB (562949819203584 bytes)
 cluster_size: 1048576
 
 Test 2: Size too large (512 TB - 128 MB + 64 kB)
@@ -35,7 +35,7 @@ qemu-img: Could not open 'TEST_DIR/t.IMGFMT': unsupported VDI image (too many bl
 Test 5: Valid Image: 64MB, Blocks In Image 64, Block Size 1MB
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 cluster_size: 1048576
 
 Test 6: Block Size != 1MB; too small test (1MB - 1)
diff --git a/tests/qemu-iotests/088.out b/tests/qemu-iotests/088.out
index 1f6bcf0abc..814be7181d 100644
--- a/tests/qemu-iotests/088.out
+++ b/tests/qemu-iotests/088.out
@@ -2,10 +2,10 @@ QA output created by 088
 
 == Invalid block size ==
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
-can't open device TEST_DIR/t.vpc: Invalid block size 0
-can't open device TEST_DIR/t.vpc: Invalid block size 0
-can't open device TEST_DIR/t.vpc: Invalid block size 128
-can't open device TEST_DIR/t.vpc: Invalid block size 128
-can't open device TEST_DIR/t.vpc: Invalid block size 305419896
-can't open device TEST_DIR/t.vpc: Invalid block size 305419896
+qemu-io: can't open device TEST_DIR/t.vpc: Invalid block size 0
+qemu-io: can't open device TEST_DIR/t.vpc: Invalid block size 0
+qemu-io: can't open device TEST_DIR/t.vpc: Invalid block size 128
+qemu-io: can't open device TEST_DIR/t.vpc: Invalid block size 128
+qemu-io: can't open device TEST_DIR/t.vpc: Invalid block size 305419896
+qemu-io: can't open device TEST_DIR/t.vpc: Invalid block size 305419896
 *** done
diff --git a/tests/qemu-iotests/089.out b/tests/qemu-iotests/089.out
index 89e3e4340a..20c8ce8f0e 100644
--- a/tests/qemu-iotests/089.out
+++ b/tests/qemu-iotests/089.out
@@ -38,7 +38,7 @@ read failed: Input/output error
 
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 cluster_size: 65536
 
 === Testing option merging ===
diff --git a/tests/qemu-iotests/095.out b/tests/qemu-iotests/095.out
index 8c093dfff3..d2e393fef8 100644
--- a/tests/qemu-iotests/095.out
+++ b/tests/qemu-iotests/095.out
@@ -6,7 +6,7 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=104857600 backing_file=TEST_DIR/
 === Base image info before commit and resize ===
 image: TEST_DIR/t.IMGFMT.base
 file format: IMGFMT
-virtual size: 5.0M (5242880 bytes)
+virtual size: 5 MiB (5242880 bytes)
 
 === Running QEMU Live Commit Test ===
 
@@ -23,5 +23,5 @@ virtual size: 5.0M (5242880 bytes)
 === Base image info after commit and resize ===
 image: TEST_DIR/t.IMGFMT.base
 file format: IMGFMT
-virtual size: 100M (104857600 bytes)
+virtual size: 100 MiB (104857600 bytes)
 *** done
diff --git a/tests/qemu-iotests/103.out b/tests/qemu-iotests/103.out
index bd9eec3250..16704cf499 100644
--- a/tests/qemu-iotests/103.out
+++ b/tests/qemu-iotests/103.out
@@ -5,13 +5,13 @@ wrote 65536/65536 bytes at offset 0
 
 === Testing invalid option combinations ===
 
-can't open device TEST_DIR/t.IMGFMT: cache-size, l2-cache-size and refcount-cache-size may not be set at the same time
-can't open device TEST_DIR/t.IMGFMT: l2-cache-size may not exceed cache-size
-can't open device TEST_DIR/t.IMGFMT: refcount-cache-size may not exceed cache-size
-can't open device TEST_DIR/t.IMGFMT: cache-size, l2-cache-size and refcount-cache-size may not be set at the same time
-can't open device TEST_DIR/t.IMGFMT: L2 cache entry size must be a power of two between 512 and the cluster size (65536)
-can't open device TEST_DIR/t.IMGFMT: L2 cache entry size must be a power of two between 512 and the cluster size (65536)
-can't open device TEST_DIR/t.IMGFMT: L2 cache entry size must be a power of two between 512 and the cluster size (65536)
+qemu-io: can't open device TEST_DIR/t.IMGFMT: cache-size, l2-cache-size and refcount-cache-size may not be set at the same time
+qemu-io: can't open device TEST_DIR/t.IMGFMT: l2-cache-size may not exceed cache-size
+qemu-io: can't open device TEST_DIR/t.IMGFMT: refcount-cache-size may not exceed cache-size
+qemu-io: can't open device TEST_DIR/t.IMGFMT: cache-size, l2-cache-size and refcount-cache-size may not be set at the same time
+qemu-io: can't open device TEST_DIR/t.IMGFMT: L2 cache entry size must be a power of two between 512 and the cluster size (65536)
+qemu-io: can't open device TEST_DIR/t.IMGFMT: L2 cache entry size must be a power of two between 512 and the cluster size (65536)
+qemu-io: can't open device TEST_DIR/t.IMGFMT: L2 cache entry size must be a power of two between 512 and the cluster size (65536)
 
 === Testing valid option combinations ===
 
diff --git a/tests/qemu-iotests/104.out b/tests/qemu-iotests/104.out
index ab8d892c2a..d854155f5b 100644
--- a/tests/qemu-iotests/104.out
+++ b/tests/qemu-iotests/104.out
@@ -4,9 +4,9 @@ QA output created by 104
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1024
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 1.0K (1024 bytes)
+virtual size: 1 KiB (1024 bytes)
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1234
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 1.5K (1536 bytes)
-***done
+virtual size: 1.5 KiB (1536 bytes)
+*** done
diff --git a/tests/qemu-iotests/110.out b/tests/qemu-iotests/110.out
index 46e6a60510..f60b26390e 100644
--- a/tests/qemu-iotests/110.out
+++ b/tests/qemu-iotests/110.out
@@ -6,14 +6,14 @@ Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=67108864
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 backing_file=t.IMGFMT.base
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 backing file: t.IMGFMT.base (actual path: TEST_DIR/t.IMGFMT.base)
 
 === Non-reconstructable filename ===
 
 image: json:{"driver": "IMGFMT", "file": {"set-state.0.event": "read_aio", "image": {"driver": "file", "filename": "TEST_DIR/t.IMGFMT"}, "driver": "blkdebug", "set-state.0.new_state": 42}}
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 backing file: t.IMGFMT.base (actual path: TEST_DIR/t.IMGFMT.base)
 
 === Backing name is always relative to the backed image ===
@@ -24,6 +24,6 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 backing_file=t.IMGFMT.b
 
 image: json:{"driver": "IMGFMT", "file": {"children": [{"driver": "file", "filename": "TEST_DIR/t.IMGFMT"}, {"driver": "file", "filename": "TEST_DIR/t.IMGFMT.copy"}], "driver": "quorum", "vote-threshold": 1}}
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 backing file: t.IMGFMT.base (cannot determine actual path)
 *** done
diff --git a/tests/qemu-iotests/114.out b/tests/qemu-iotests/114.out
index 1a47a526b9..67adef37a4 100644
--- a/tests/qemu-iotests/114.out
+++ b/tests/qemu-iotests/114.out
@@ -3,11 +3,11 @@ Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=67108864
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 backing_file=TEST_DIR/t.IMGFMT.base
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 cluster_size: 65536
 backing file: TEST_DIR/t.IMGFMT.base
 backing file format: foo
-can't open device TEST_DIR/t.qcow2: Could not open backing file: Unknown driver 'foo'
+qemu-io: can't open device TEST_DIR/t.qcow2: Could not open backing file: Unknown driver 'foo'
 no file open, try 'help open'
 read 4096/4096 bytes at offset 0
 4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
diff --git a/tests/qemu-iotests/116.out b/tests/qemu-iotests/116.out
index 24bee57783..49f9a261a0 100644
--- a/tests/qemu-iotests/116.out
+++ b/tests/qemu-iotests/116.out
@@ -2,29 +2,29 @@ QA output created by 116
 
 == truncated header cluster ==
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
-can't open device TEST_DIR/t.qed: Could not open 'TEST_DIR/t.qed': Invalid argument
+qemu-io: can't open device TEST_DIR/t.qed: Could not open 'TEST_DIR/t.qed': Invalid argument
 
 == invalid header magic ==
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
-can't open device TEST_DIR/t.qed: Image not in QED format
+qemu-io: can't open device TEST_DIR/t.qed: Image not in QED format
 
 == invalid cluster size ==
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
-can't open device TEST_DIR/t.qed: Could not open 'TEST_DIR/t.qed': Invalid argument
+qemu-io: can't open device TEST_DIR/t.qed: Could not open 'TEST_DIR/t.qed': Invalid argument
 
 == invalid table size ==
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
-can't open device TEST_DIR/t.qed: Could not open 'TEST_DIR/t.qed': Invalid argument
+qemu-io: can't open device TEST_DIR/t.qed: Could not open 'TEST_DIR/t.qed': Invalid argument
 
 == invalid header size ==
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
-can't open device TEST_DIR/t.qed: Could not open 'TEST_DIR/t.qed': Invalid argument
+qemu-io: can't open device TEST_DIR/t.qed: Could not open 'TEST_DIR/t.qed': Invalid argument
 
 == invalid L1 table offset ==
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
-can't open device TEST_DIR/t.qed: Could not open 'TEST_DIR/t.qed': Invalid argument
+qemu-io: can't open device TEST_DIR/t.qed: Could not open 'TEST_DIR/t.qed': Invalid argument
 
 == invalid image size ==
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
-can't open device TEST_DIR/t.qed: Could not open 'TEST_DIR/t.qed': Invalid argument
+qemu-io: can't open device TEST_DIR/t.qed: Could not open 'TEST_DIR/t.qed': Invalid argument
 *** done
diff --git a/tests/qemu-iotests/126.out b/tests/qemu-iotests/126.out
index 17d03d5248..e3c4d61916 100644
--- a/tests/qemu-iotests/126.out
+++ b/tests/qemu-iotests/126.out
@@ -11,13 +11,13 @@ Formatting 'TEST_DIR/image:base.IMGFMT', fmt=IMGFMT size=67108864
 Formatting 'TEST_DIR/image:top.IMGFMT', fmt=IMGFMT size=67108864 backing_file=./image:base.IMGFMT
 image: TEST_DIR/image:top.IMGFMT
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 backing file: ./image:base.IMGFMT (actual path: TEST_DIR/./image:base.IMGFMT)
 
 Formatting 'base.IMGFMT', fmt=IMGFMT size=67108864
 Formatting 'file:image:top.IMGFMT', fmt=IMGFMT size=67108864 backing_file=base.IMGFMT
 image: ./image:top.IMGFMT
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 backing file: base.IMGFMT (actual path: ./base.IMGFMT)
 *** done
diff --git a/tests/qemu-iotests/130.out b/tests/qemu-iotests/130.out
index 93020c328e..e45285ccc3 100644
--- a/tests/qemu-iotests/130.out
+++ b/tests/qemu-iotests/130.out
@@ -4,7 +4,7 @@ Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=67108864
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 
 === HMP commit ===
 
@@ -13,14 +13,14 @@ QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) 
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 backing_file=TEST_DIR/t.IMGFMT.orig backing_fmt=raw
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) commit testdisk
 (qemu) 
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 backing file: TEST_DIR/t.IMGFMT.orig
 backing file format: raw
 
@@ -31,13 +31,13 @@ wrote 4096/4096 bytes at offset 0
 4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 backing_file=TEST_DIR/t.IMGFMT.orig backing_fmt=raw
 wrote 4096/4096 bytes at offset 0
 4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 backing file: TEST_DIR/t.IMGFMT.orig
 backing file format: raw
 *** done
diff --git a/tests/qemu-iotests/131.out b/tests/qemu-iotests/131.out
index 27c2c5389b..70da03dee5 100644
--- a/tests/qemu-iotests/131.out
+++ b/tests/qemu-iotests/131.out
@@ -22,7 +22,7 @@ read 32768/32768 bytes at offset 163840
 read 32768/32768 bytes at offset 0
 32 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 == Corrupt image ==
-can't open device TEST_DIR/t.parallels: parallels: Image was not closed correctly; cannot be opened read/write
+qemu-io: can't open device TEST_DIR/t.parallels: parallels: Image was not closed correctly; cannot be opened read/write
 ERROR image was not closed correctly
 
 1 errors were found on the image.
diff --git a/tests/qemu-iotests/133.out b/tests/qemu-iotests/133.out
index 414c7fa27f..1491ef45a9 100644
--- a/tests/qemu-iotests/133.out
+++ b/tests/qemu-iotests/133.out
@@ -4,18 +4,18 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 backing_file=TEST_DIR/t
 
 === Check that node-name can't be changed ===
 
-Cannot change the option 'node-name'
-Cannot change the option 'node-name'
-Cannot change the option 'node-name'
+qemu-io: Cannot change the option 'node-name'
+qemu-io: Cannot change the option 'node-name'
+qemu-io: Cannot change the option 'node-name'
 
 === Check that unchanged node-name is okay ===
 
 
 === Check that driver can't be changed ===
 
-Cannot change the option 'driver'
-Cannot change the option 'driver'
-Cannot change the option 'driver'
+qemu-io: Cannot change the option 'driver'
+qemu-io: Cannot change the option 'driver'
+qemu-io: Cannot change the option 'driver'
 
 === Check that unchanged driver is okay ===
 
@@ -27,16 +27,16 @@ format name: null-co
 
 === Check that mixing -c/-r/-w and their corresponding options is forbidden ===
 
-Cannot set both -r/-w and 'read-only'
-Cannot set both -r/-w and 'read-only'
-Cannot set both -c and the cache options
-Cannot set both -c and the cache options
-Cannot set both -c and the cache options
+qemu-io: Cannot set both -r/-w and 'read-only'
+qemu-io: Cannot set both -r/-w and 'read-only'
+qemu-io: Cannot set both -c and the cache options
+qemu-io: Cannot set both -c and the cache options
+qemu-io: Cannot set both -c and the cache options
 
 === Check that invalid options are handled correctly ===
 
-Parameter 'read-only' expects 'on' or 'off'
-Parameter 'cache.no-flush' expects 'on' or 'off'
-Parameter 'cache.direct' expects 'on' or 'off'
-Parameter 'auto-read-only' expects 'on' or 'off'
+qemu-io: Parameter 'read-only' expects 'on' or 'off'
+qemu-io: Parameter 'cache.no-flush' expects 'on' or 'off'
+qemu-io: Parameter 'cache.direct' expects 'on' or 'off'
+qemu-io: Parameter 'auto-read-only' expects 'on' or 'off'
 *** done
diff --git a/tests/qemu-iotests/137.out b/tests/qemu-iotests/137.out
index 2c080b72f3..22d59df40c 100644
--- a/tests/qemu-iotests/137.out
+++ b/tests/qemu-iotests/137.out
@@ -15,24 +15,24 @@ read 33554432/33554432 bytes at offset 0
 
 === Try setting some invalid values ===
 
-Parameter 'lazy-refcounts' expects 'on' or 'off'
-cache-size, l2-cache-size and refcount-cache-size may not be set at the same time
-l2-cache-size may not exceed cache-size
-refcount-cache-size may not exceed cache-size
-L2 cache entry size must be a power of two between 512 and the cluster size (65536)
-L2 cache entry size must be a power of two between 512 and the cluster size (65536)
-Refcount cache size too big
-Conflicting values for qcow2 options 'overlap-check' ('constant') and 'overlap-check.template' ('all')
-Unsupported value 'blubb' for qcow2 option 'overlap-check'. Allowed are any of the following: none, constant, cached, all
-Unsupported value 'blubb' for qcow2 option 'overlap-check'. Allowed are any of the following: none, constant, cached, all
-Cache clean interval too big
+qemu-io: Parameter 'lazy-refcounts' expects 'on' or 'off'
+qemu-io: cache-size, l2-cache-size and refcount-cache-size may not be set at the same time
+qemu-io: l2-cache-size may not exceed cache-size
+qemu-io: refcount-cache-size may not exceed cache-size
+qemu-io: L2 cache entry size must be a power of two between 512 and the cluster size (65536)
+qemu-io: L2 cache entry size must be a power of two between 512 and the cluster size (65536)
+qemu-io: Refcount cache size too big
+qemu-io: Conflicting values for qcow2 options 'overlap-check' ('constant') and 'overlap-check.template' ('all')
+qemu-io: Unsupported value 'blubb' for qcow2 option 'overlap-check'. Allowed are any of the following: none, constant, cached, all
+qemu-io: Unsupported value 'blubb' for qcow2 option 'overlap-check'. Allowed are any of the following: none, constant, cached, all
+qemu-io: Cache clean interval too big
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=36028797018963968
-L2 cache size too big
+qemu-io: L2 cache size too big
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
 
 === Test transaction semantics ===
 
-Unsupported value 'blubb' for qcow2 option 'overlap-check'. Allowed are any of the following: none, constant, cached, all
+qemu-io: Unsupported value 'blubb' for qcow2 option 'overlap-check'. Allowed are any of the following: none, constant, cached, all
 wrote 512/512 bytes at offset 0
 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 ./common.rc: Killed                  ( if [ "${VALGRIND_QEMU}" == "y" ]; then
@@ -44,7 +44,7 @@ incompatible_features     0x0
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
 wrote 65536/65536 bytes at offset 0
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-Parameter 'lazy-refcounts' expects 'on' or 'off'
+qemu-io: Parameter 'lazy-refcounts' expects 'on' or 'off'
 qcow2: Marking image as corrupt: Preventing invalid write on metadata (overlaps with qcow2_header); further corruption events will be suppressed
 write failed: Input/output error
 *** done
diff --git a/tests/qemu-iotests/140.out b/tests/qemu-iotests/140.out
index 704adcef40..67fe44a3e3 100644
--- a/tests/qemu-iotests/140.out
+++ b/tests/qemu-iotests/140.out
@@ -8,7 +8,7 @@ wrote 65536/65536 bytes at offset 0
 read 65536/65536 bytes at offset 0
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 {"return": {}}
-can't open device nbd+unix:///drv?socket=TEST_DIR/nbd: Requested export not available
+qemu-io: can't open device nbd+unix:///drv?socket=TEST_DIR/nbd: Requested export not available
 server reported: export 'drv' not present
 {"return": {}}
 {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "SHUTDOWN", "data": {"guest": false, "reason": "host-qmp-quit"}}
diff --git a/tests/qemu-iotests/143.out b/tests/qemu-iotests/143.out
index 3e55fcd0ac..ee71b5aa42 100644
--- a/tests/qemu-iotests/143.out
+++ b/tests/qemu-iotests/143.out
@@ -1,7 +1,7 @@
 QA output created by 143
 {"return": {}}
 {"return": {}}
-can't open device nbd+unix:///no_such_export?socket=TEST_DIR/nbd: Requested export not available
+qemu-io: can't open device nbd+unix:///no_such_export?socket=TEST_DIR/nbd: Requested export not available
 server reported: export 'no_such_export' not present
 {"return": {}}
 {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "SHUTDOWN", "data": {"guest": false, "reason": "host-qmp-quit"}}
diff --git a/tests/qemu-iotests/153.out b/tests/qemu-iotests/153.out
index 9747ce3c41..e969420006 100644
--- a/tests/qemu-iotests/153.out
+++ b/tests/qemu-iotests/153.out
@@ -23,20 +23,20 @@ Is another process using the image [TEST_DIR/t.qcow2]?
 == Running utility commands  ==
 
 _qemu_io_wrapper -c read 0 512 TEST_DIR/t.qcow2
-can't open device TEST_DIR/t.qcow2: Failed to get "write" lock
+qemu-io: can't open device TEST_DIR/t.qcow2: Failed to get "write" lock
 Is another process using the image [TEST_DIR/t.qcow2]?
 
 _qemu_io_wrapper -r -c read 0 512 TEST_DIR/t.qcow2
-can't open device TEST_DIR/t.qcow2: Failed to get shared "write" lock
+qemu-io: can't open device TEST_DIR/t.qcow2: Failed to get shared "write" lock
 Is another process using the image [TEST_DIR/t.qcow2]?
 
 _qemu_io_wrapper -c open  TEST_DIR/t.qcow2 -c read 0 512
-can't open device TEST_DIR/t.qcow2: Failed to get "write" lock
+qemu-io: can't open device TEST_DIR/t.qcow2: Failed to get "write" lock
 Is another process using the image [TEST_DIR/t.qcow2]?
 no file open, try 'help open'
 
 _qemu_io_wrapper -c open -r  TEST_DIR/t.qcow2 -c read 0 512
-can't open device TEST_DIR/t.qcow2: Failed to get shared "write" lock
+qemu-io: can't open device TEST_DIR/t.qcow2: Failed to get shared "write" lock
 Is another process using the image [TEST_DIR/t.qcow2]?
 no file open, try 'help open'
 
@@ -100,12 +100,12 @@ file format: IMGFMT
 == Running utility commands -U ==
 
 _qemu_io_wrapper -U -c read 0 512 TEST_DIR/t.qcow2
-can't open device TEST_DIR/t.qcow2: force-share=on can only be used with read-only images
+qemu-io: can't open device TEST_DIR/t.qcow2: force-share=on can only be used with read-only images
 
 _qemu_io_wrapper -U -r -c read 0 512 TEST_DIR/t.qcow2
 
 _qemu_io_wrapper -c open -U TEST_DIR/t.qcow2 -c read 0 512
-can't open device TEST_DIR/t.qcow2: force-share=on can only be used with read-only images
+qemu-io: can't open device TEST_DIR/t.qcow2: force-share=on can only be used with read-only images
 no file open, try 'help open'
 
 _qemu_io_wrapper -c open -r -U TEST_DIR/t.qcow2 -c read 0 512
@@ -166,13 +166,13 @@ Is another process using the image [TEST_DIR/t.qcow2]?
 == Running utility commands  ==
 
 _qemu_io_wrapper -c read 0 512 TEST_DIR/t.qcow2
-can't open device TEST_DIR/t.qcow2: Failed to get "write" lock
+qemu-io: can't open device TEST_DIR/t.qcow2: Failed to get "write" lock
 Is another process using the image [TEST_DIR/t.qcow2]?
 
 _qemu_io_wrapper -r -c read 0 512 TEST_DIR/t.qcow2
 
 _qemu_io_wrapper -c open  TEST_DIR/t.qcow2 -c read 0 512
-can't open device TEST_DIR/t.qcow2: Failed to get "write" lock
+qemu-io: can't open device TEST_DIR/t.qcow2: Failed to get "write" lock
 Is another process using the image [TEST_DIR/t.qcow2]?
 no file open, try 'help open'
 
@@ -222,12 +222,12 @@ file format: IMGFMT
 == Running utility commands -U ==
 
 _qemu_io_wrapper -U -c read 0 512 TEST_DIR/t.qcow2
-can't open device TEST_DIR/t.qcow2: force-share=on can only be used with read-only images
+qemu-io: can't open device TEST_DIR/t.qcow2: force-share=on can only be used with read-only images
 
 _qemu_io_wrapper -U -r -c read 0 512 TEST_DIR/t.qcow2
 
 _qemu_io_wrapper -c open -U TEST_DIR/t.qcow2 -c read 0 512
-can't open device TEST_DIR/t.qcow2: force-share=on can only be used with read-only images
+qemu-io: can't open device TEST_DIR/t.qcow2: force-share=on can only be used with read-only images
 no file open, try 'help open'
 
 _qemu_io_wrapper -c open -r -U TEST_DIR/t.qcow2 -c read 0 512
@@ -325,12 +325,12 @@ file format: IMGFMT
 == Running utility commands -U ==
 
 _qemu_io_wrapper -U -c read 0 512 TEST_DIR/t.qcow2
-can't open device TEST_DIR/t.qcow2: force-share=on can only be used with read-only images
+qemu-io: can't open device TEST_DIR/t.qcow2: force-share=on can only be used with read-only images
 
 _qemu_io_wrapper -U -r -c read 0 512 TEST_DIR/t.qcow2
 
 _qemu_io_wrapper -c open -U TEST_DIR/t.qcow2 -c read 0 512
-can't open device TEST_DIR/t.qcow2: force-share=on can only be used with read-only images
+qemu-io: can't open device TEST_DIR/t.qcow2: force-share=on can only be used with read-only images
 no file open, try 'help open'
 
 _qemu_io_wrapper -c open -r -U TEST_DIR/t.qcow2 -c read 0 512
@@ -420,7 +420,7 @@ Adding drive
 {"return": "OKrn"}
 
 _qemu_io_wrapper TEST_DIR/t.qcow2 -c write 0 512
-can't open device TEST_DIR/t.qcow2: Failed to get "write" lock
+qemu-io: can't open device TEST_DIR/t.qcow2: Failed to get "write" lock
 Is another process using the image [TEST_DIR/t.qcow2]?
 Creating overlay with qemu-img when the guest is running should be allowed
 
@@ -437,7 +437,7 @@ _qemu_img_wrapper info TEST_DIR/t.qcow2
 {"return": ""}
 
 _qemu_io_wrapper TEST_DIR/t.qcow2 -c write 0 512
-can't open device TEST_DIR/t.qcow2: Failed to get "write" lock
+qemu-io: can't open device TEST_DIR/t.qcow2: Failed to get "write" lock
 Is another process using the image [TEST_DIR/t.qcow2]?
 Closing the other
 {"return": ""}
@@ -449,7 +449,7 @@ _qemu_io_wrapper TEST_DIR/t.qcow2 -c write 0 512
 No conflict:
 image: null-co://
 file format: null-co
-virtual size: 1.0G (1073741824 bytes)
+virtual size: 1 GiB (1073741824 bytes)
 disk size: unavailable
 
 Conflict:
@@ -458,5 +458,5 @@ qemu-img: --force-share/-U conflicts with image options
 No conflict:
 
 Conflict:
--U conflicts with image options
+qemu-io: -U conflicts with image options
 *** done
diff --git a/tests/qemu-iotests/187.out b/tests/qemu-iotests/187.out
index 30b987f71f..86203d8abc 100644
--- a/tests/qemu-iotests/187.out
+++ b/tests/qemu-iotests/187.out
@@ -3,16 +3,16 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
 
 Start from read-only
 
-Block node is read-only
+qemu-io: Block node is read-only
 wrote 65536/65536 bytes at offset 0
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-Block node is read-only
+qemu-io: Block node is read-only
 
 Start from read-write
 
 wrote 65536/65536 bytes at offset 0
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-Block node is read-only
+qemu-io: Block node is read-only
 wrote 65536/65536 bytes at offset 0
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 *** done
diff --git a/tests/qemu-iotests/188.out b/tests/qemu-iotests/188.out
index 8af24e5d8b..97b1402671 100644
--- a/tests/qemu-iotests/188.out
+++ b/tests/qemu-iotests/188.out
@@ -14,5 +14,5 @@ read 16777216/16777216 bytes at offset 0
 16 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 
 == verify open failure with wrong password ==
-can't open: Invalid password, cannot unlock any keyslot
+qemu-io: can't open: Invalid password, cannot unlock any keyslot
 *** done
diff --git a/tests/qemu-iotests/191.out b/tests/qemu-iotests/191.out
index a513ccca0b..3fc92bb56e 100644
--- a/tests/qemu-iotests/191.out
+++ b/tests/qemu-iotests/191.out
@@ -395,13 +395,13 @@ wrote 65536/65536 bytes at offset 1048576
 }
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 cluster_size: 65536
 backing file: TEST_DIR/t.IMGFMT.base
 backing file format: IMGFMT
 image: TEST_DIR/t.IMGFMT.ovl2
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 cluster_size: 65536
 backing file: TEST_DIR/t.IMGFMT.base
 backing file format: IMGFMT
@@ -813,13 +813,13 @@ wrote 65536/65536 bytes at offset 1048576
 }
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 cluster_size: 65536
 backing file: TEST_DIR/t.IMGFMT.base
 backing file format: IMGFMT
 image: TEST_DIR/t.IMGFMT.ovl2
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 cluster_size: 65536
 backing file: TEST_DIR/t.IMGFMT.base
 backing file format: IMGFMT
diff --git a/tests/qemu-iotests/195.out b/tests/qemu-iotests/195.out
index 1e9330b1be..e6df0d6781 100644
--- a/tests/qemu-iotests/195.out
+++ b/tests/qemu-iotests/195.out
@@ -35,7 +35,7 @@ Testing: -drive if=none,file=TEST_DIR/t.IMGFMT,backing.node-name=mid
 
 image: TEST_DIR/t.IMGFMT.mid
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 cluster_size: 65536
 backing file: /dev/null
 backing file format: IMGFMT
@@ -73,7 +73,7 @@ Testing: -drive if=none,file=TEST_DIR/t.IMGFMT,node-name=top
 
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 cluster_size: 65536
 backing file: /dev/null
 backing file format: IMGFMT
diff --git a/tests/qemu-iotests/197.out b/tests/qemu-iotests/197.out
index 8febda5dea..7ca46be6e4 100644
--- a/tests/qemu-iotests/197.out
+++ b/tests/qemu-iotests/197.out
@@ -16,7 +16,7 @@ read 2147483136/2147483136 bytes at offset 1024
 2 GiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 1024/1024 bytes at offset 3221226496
 1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-can't open device TEST_DIR/t.wrap.qcow2: Can't use copy-on-read on read-only device
+qemu-io: can't open device TEST_DIR/t.wrap.qcow2: Can't use copy-on-read on read-only device
 2 GiB (0x80010000) bytes     allocated at offset 0 bytes (0x0)
 1023.938 MiB (0x3fff0000) bytes not allocated at offset 2 GiB (0x80010000)
 64 KiB (0x10000) bytes     allocated at offset 3 GiB (0xc0000000)
diff --git a/tests/qemu-iotests/198.out b/tests/qemu-iotests/198.out
index adb805cce9..e86b175e39 100644
--- a/tests/qemu-iotests/198.out
+++ b/tests/qemu-iotests/198.out
@@ -34,7 +34,7 @@ read 16777216/16777216 bytes at offset 0
 == checking image base ==
 image: json:{"encrypt.key-secret": "sec0", "driver": "IMGFMT", "file": {"driver": "file", "filename": "TEST_DIR/t.IMGFMT.base"}}
 file format: IMGFMT
-virtual size: 16M (16777216 bytes)
+virtual size: 16 MiB (16777216 bytes)
 Format specific information:
     encrypt:
         ivgen alg: plain64
@@ -76,7 +76,7 @@ Format specific information:
 == checking image layer ==
 image: json:{"encrypt.key-secret": "sec1", "driver": "IMGFMT", "file": {"driver": "file", "filename": "TEST_DIR/t.IMGFMT"}}
 file format: IMGFMT
-virtual size: 16M (16777216 bytes)
+virtual size: 16 MiB (16777216 bytes)
 backing file: TEST_DIR/t.IMGFMT.base
 Format specific information:
     encrypt:
diff --git a/tests/qemu-iotests/205 b/tests/qemu-iotests/205
index 31b2f5707a..69f2c1d392 100755
--- a/tests/qemu-iotests/205
+++ b/tests/qemu-iotests/205
@@ -78,7 +78,7 @@ class TestNbdServerRemove(iotests.QMPTestCase):
 
     def assertConnectFailed(self, qemu_io_output):
         self.assertEqual(filter_qemu_io(qemu_io_output).strip(),
-                         "can't open device " + nbd_uri +
+                         "qemu-io: can't open device " + nbd_uri +
                          ": Requested export not available\n"
                          "server reported: export 'exp' not present")
 
diff --git a/tests/qemu-iotests/206.out b/tests/qemu-iotests/206.out
index 0f1c23babb..61e7241e0b 100644
--- a/tests/qemu-iotests/206.out
+++ b/tests/qemu-iotests/206.out
@@ -14,7 +14,7 @@
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 128M (134217728 bytes)
+virtual size: 128 MiB (134217728 bytes)
 cluster_size: 65536
 Format specific information:
     compat: 1.1
@@ -36,7 +36,7 @@ Format specific information:
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 cluster_size: 65536
 Format specific information:
     compat: 1.1
@@ -58,7 +58,7 @@ Format specific information:
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 32M (33554432 bytes)
+virtual size: 32 MiB (33554432 bytes)
 cluster_size: 2097152
 Format specific information:
     compat: 1.1
@@ -80,7 +80,7 @@ Format specific information:
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 32M (33554432 bytes)
+virtual size: 32 MiB (33554432 bytes)
 cluster_size: 512
 backing file: TEST_IMG.base
 backing file format: IMGFMT
@@ -97,7 +97,7 @@ Format specific information:
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 32M (33554432 bytes)
+virtual size: 32 MiB (33554432 bytes)
 encrypted: yes
 cluster_size: 65536
 Format specific information:
diff --git a/tests/qemu-iotests/207.out b/tests/qemu-iotests/207.out
index 568e8619d0..979d5cf745 100644
--- a/tests/qemu-iotests/207.out
+++ b/tests/qemu-iotests/207.out
@@ -7,12 +7,12 @@
 
 image: json:{"driver": "IMGFMT", "file": {"server.host": "127.0.0.1", "server.port": "22", "driver": "ssh", "path": "TEST_IMG"}}
 file format: IMGFMT
-virtual size: 4.0M (4194304 bytes)
+virtual size: 4 MiB (4194304 bytes)
 
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 4.0M (4194304 bytes)
+virtual size: 4 MiB (4194304 bytes)
 
 === Test host-key-check options ===
 
@@ -23,7 +23,7 @@ virtual size: 4.0M (4194304 bytes)
 
 image: json:{"driver": "IMGFMT", "file": {"server.host": "127.0.0.1", "server.port": "22", "driver": "ssh", "path": "TEST_IMG"}}
 file format: IMGFMT
-virtual size: 8.0M (8388608 bytes)
+virtual size: 8 MiB (8388608 bytes)
 
 {"execute": "blockdev-create", "arguments": {"job-id": "job0", "options": {"driver": "ssh", "location": {"host-key-check": {"mode": "known_hosts"}, "path": "TEST_DIR/PID-t.img", "server": {"host": "127.0.0.1", "port": "22"}}, "size": 4194304}}}
 {"return": {}}
@@ -32,7 +32,7 @@ virtual size: 8.0M (8388608 bytes)
 
 image: json:{"driver": "IMGFMT", "file": {"server.host": "127.0.0.1", "server.port": "22", "driver": "ssh", "path": "TEST_IMG"}}
 file format: IMGFMT
-virtual size: 4.0M (4194304 bytes)
+virtual size: 4 MiB (4194304 bytes)
 
 {"execute": "blockdev-create", "arguments": {"job-id": "job0", "options": {"driver": "ssh", "location": {"host-key-check": {"hash": "wrong", "mode": "hash", "type": "md5"}, "path": "TEST_DIR/PID-t.img", "server": {"host": "127.0.0.1", "port": "22"}}, "size": 2097152}}}
 {"return": {}}
@@ -47,7 +47,7 @@ Job failed: remote host key does not match host_key_check 'wrong'
 
 image: json:{"driver": "IMGFMT", "file": {"server.host": "127.0.0.1", "server.port": "22", "driver": "ssh", "path": "TEST_IMG"}}
 file format: IMGFMT
-virtual size: 8.0M (8388608 bytes)
+virtual size: 8 MiB (8388608 bytes)
 
 {"execute": "blockdev-create", "arguments": {"job-id": "job0", "options": {"driver": "ssh", "location": {"host-key-check": {"hash": "wrong", "mode": "hash", "type": "sha1"}, "path": "TEST_DIR/PID-t.img", "server": {"host": "127.0.0.1", "port": "22"}}, "size": 2097152}}}
 {"return": {}}
@@ -62,7 +62,7 @@ Job failed: remote host key does not match host_key_check 'wrong'
 
 image: json:{"driver": "IMGFMT", "file": {"server.host": "127.0.0.1", "server.port": "22", "driver": "ssh", "path": "TEST_IMG"}}
 file format: IMGFMT
-virtual size: 4.0M (4194304 bytes)
+virtual size: 4 MiB (4194304 bytes)
 
 === Invalid path and user ===
 
diff --git a/tests/qemu-iotests/210.out b/tests/qemu-iotests/210.out
index a3692ce00d..a5e88e2a82 100644
--- a/tests/qemu-iotests/210.out
+++ b/tests/qemu-iotests/210.out
@@ -14,7 +14,7 @@
 
 image: json:{"driver": "IMGFMT", "file": {"driver": "file", "filename": "TEST_IMG"}, "key-secret": "keysec0"}
 file format: IMGFMT
-virtual size: 128M (134217728 bytes)
+virtual size: 128 MiB (134217728 bytes)
 encrypted: yes
 Format specific information:
     ivgen alg: plain64
@@ -66,7 +66,7 @@ Format specific information:
 
 image: json:{"driver": "IMGFMT", "file": {"driver": "file", "filename": "TEST_IMG"}, "key-secret": "keysec0"}
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 encrypted: yes
 Format specific information:
     ivgen alg: plain64
@@ -121,7 +121,7 @@ Job failed: Cannot find device=this doesn't exist nor node_name=this doesn't exi
 
 image: json:{"driver": "IMGFMT", "file": {"driver": "file", "filename": "TEST_IMG"}, "key-secret": "keysec0"}
 file format: IMGFMT
-virtual size: 0 (0 bytes)
+virtual size: 0 B (0 bytes)
 encrypted: yes
 Format specific information:
     ivgen alg: plain64
@@ -191,7 +191,7 @@ Job failed: The requested file size is too large
 {"error": {"class": "GenericError", "desc": "Parameter 'size' expects a >0 size"}}
 image: json:{"driver": "IMGFMT", "file": {"driver": "file", "filename": "TEST_IMG"}, "key-secret": "keysec0"}
 file format: IMGFMT
-virtual size: 0 (0 bytes)
+virtual size: 0 B (0 bytes)
 encrypted: yes
 Format specific information:
     ivgen alg: plain64
diff --git a/tests/qemu-iotests/211.out b/tests/qemu-iotests/211.out
index 682adc2a10..b83384deea 100644
--- a/tests/qemu-iotests/211.out
+++ b/tests/qemu-iotests/211.out
@@ -14,7 +14,7 @@
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 128M (134217728 bytes)
+virtual size: 128 MiB (134217728 bytes)
 cluster_size: 1048576
 
 [{ "start": 0, "length": 134217728, "depth": 0, "zero": true, "data": false}]
@@ -33,7 +33,7 @@ cluster_size: 1048576
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 cluster_size: 1048576
 
 [{ "start": 0, "length": 67108864, "depth": 0, "zero": true, "data": false}]
@@ -52,7 +52,7 @@ cluster_size: 1048576
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 32M (33554432 bytes)
+virtual size: 32 MiB (33554432 bytes)
 cluster_size: 1048576
 
 [{ "start": 0, "length": 3072, "depth": 0, "zero": false, "data": true, "offset": 1024},
@@ -75,7 +75,7 @@ Job failed: Cannot find device=this doesn't exist nor node_name=this doesn't exi
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 0 (0 bytes)
+virtual size: 0 B (0 bytes)
 cluster_size: 1048576
 
 === Maximum size ===
@@ -87,7 +87,7 @@ cluster_size: 1048576
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 512T (562949819203584 bytes)
+virtual size: 512 TiB (562949819203584 bytes)
 cluster_size: 1048576
 
 === Invalid sizes ===
diff --git a/tests/qemu-iotests/212.out b/tests/qemu-iotests/212.out
index 22810720cf..1538d679be 100644
--- a/tests/qemu-iotests/212.out
+++ b/tests/qemu-iotests/212.out
@@ -14,7 +14,7 @@
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 128M (134217728 bytes)
+virtual size: 128 MiB (134217728 bytes)
 
 === Successful image creation (explicit defaults) ===
 
@@ -30,7 +30,7 @@ virtual size: 128M (134217728 bytes)
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 
 === Successful image creation (with non-default options) ===
 
@@ -46,7 +46,7 @@ virtual size: 64M (67108864 bytes)
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 32M (33554432 bytes)
+virtual size: 32 MiB (33554432 bytes)
 
 === Invalid BlockdevRef ===
 
@@ -65,7 +65,7 @@ Job failed: Cannot find device=this doesn't exist nor node_name=this doesn't exi
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 0 (0 bytes)
+virtual size: 0 B (0 bytes)
 
 === Maximum size ===
 
@@ -76,7 +76,7 @@ virtual size: 0 (0 bytes)
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 4096T (4503599627369984 bytes)
+virtual size: 4 PiB (4503599627369984 bytes)
 
 === Invalid sizes ===
 
diff --git a/tests/qemu-iotests/213.out b/tests/qemu-iotests/213.out
index 169083e08e..be4ae85180 100644
--- a/tests/qemu-iotests/213.out
+++ b/tests/qemu-iotests/213.out
@@ -14,7 +14,7 @@
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 128M (134217728 bytes)
+virtual size: 128 MiB (134217728 bytes)
 cluster_size: 8388608
 
 === Successful image creation (explicit defaults) ===
@@ -31,7 +31,7 @@ cluster_size: 8388608
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 cluster_size: 8388608
 
 === Successful image creation (with non-default options) ===
@@ -48,7 +48,7 @@ cluster_size: 8388608
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 32M (33554432 bytes)
+virtual size: 32 MiB (33554432 bytes)
 cluster_size: 268435456
 
 === Invalid BlockdevRef ===
@@ -68,7 +68,7 @@ Job failed: Cannot find device=this doesn't exist nor node_name=this doesn't exi
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 0 (0 bytes)
+virtual size: 0 B (0 bytes)
 cluster_size: 8388608
 
 === Maximum size ===
@@ -80,7 +80,7 @@ cluster_size: 8388608
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 64T (70368744177664 bytes)
+virtual size: 64 TiB (70368744177664 bytes)
 cluster_size: 67108864
 
 === Invalid sizes ===
diff --git a/tests/qemu-iotests/215.out b/tests/qemu-iotests/215.out
index 70b0f5fb19..5a2fe40d03 100644
--- a/tests/qemu-iotests/215.out
+++ b/tests/qemu-iotests/215.out
@@ -16,7 +16,7 @@ read 2147483136/2147483136 bytes at offset 1024
 2 GiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 1024/1024 bytes at offset 3221226496
 1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-can't open device TEST_DIR/t.wrap.qcow2: Block node is read-only
+qemu-io: can't open device TEST_DIR/t.wrap.qcow2: Block node is read-only
 2 GiB (0x80010000) bytes     allocated at offset 0 bytes (0x0)
 1023.938 MiB (0x3fff0000) bytes not allocated at offset 2 GiB (0x80010000)
 64 KiB (0x10000) bytes     allocated at offset 3 GiB (0xc0000000)
diff --git a/tests/qemu-iotests/226.out b/tests/qemu-iotests/226.out
index 8c0d060ffc..42be973ff2 100644
--- a/tests/qemu-iotests/226.out
+++ b/tests/qemu-iotests/226.out
@@ -3,24 +3,24 @@ QA output created by 226
 === Testing with driver:file ===
 
 == Testing RO ==
-can't open: A regular file was expected by the 'file' driver, but something else was given
-warning: Opening a character device as a file using the 'file' driver is deprecated
+qemu-io: can't open: A regular file was expected by the 'file' driver, but something else was given
+qemu-io: warning: Opening a character device as a file using the 'file' driver is deprecated
 == Testing RW ==
-can't open: Could not open 'TEST_DIR/t.IMGFMT': Is a directory
-warning: Opening a character device as a file using the 'file' driver is deprecated
+qemu-io: can't open: Could not open 'TEST_DIR/t.IMGFMT': Is a directory
+qemu-io: warning: Opening a character device as a file using the 'file' driver is deprecated
 
 === Testing with driver:host_device ===
 
 == Testing RO ==
-can't open: 'host_device' driver expects either a character or block device
+qemu-io: can't open: 'host_device' driver expects either a character or block device
 == Testing RW ==
-can't open: Could not open 'TEST_DIR/t.IMGFMT': Is a directory
+qemu-io: can't open: Could not open 'TEST_DIR/t.IMGFMT': Is a directory
 
 === Testing with driver:host_cdrom ===
 
 == Testing RO ==
-can't open: 'host_cdrom' driver expects either a character or block device
+qemu-io: can't open: 'host_cdrom' driver expects either a character or block device
 == Testing RW ==
-can't open: Could not open 'TEST_DIR/t.IMGFMT': Is a directory
+qemu-io: can't open: Could not open 'TEST_DIR/t.IMGFMT': Is a directory
 
 *** done
diff --git a/tests/qemu-iotests/233.out b/tests/qemu-iotests/233.out
index 9511b6ea65..4edc2dd5cf 100644
--- a/tests/qemu-iotests/233.out
+++ b/tests/qemu-iotests/233.out
@@ -28,11 +28,11 @@ server reported: Option 0x8 not permitted before TLS
 == check TLS works ==
 image: nbd://127.0.0.1:PORT
 file format: nbd
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 disk size: unavailable
 image: nbd://127.0.0.1:PORT
 file format: nbd
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 disk size: unavailable
 exports available: 1
  export: ''
diff --git a/tests/qemu-iotests/237.out b/tests/qemu-iotests/237.out
index 2aaa68f672..a8c800bfad 100644
--- a/tests/qemu-iotests/237.out
+++ b/tests/qemu-iotests/237.out
@@ -14,7 +14,7 @@
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 5.0G (5368709120 bytes)
+virtual size: 5 GiB (5368709120 bytes)
 cluster_size: 65536
 Format specific information:
     cid: XXXXXXXXXX
@@ -41,7 +41,7 @@ Format specific information:
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 64M (67108864 bytes)
+virtual size: 64 MiB (67108864 bytes)
 cluster_size: 65536
 Format specific information:
     cid: XXXXXXXXXX
@@ -68,7 +68,7 @@ Format specific information:
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 32M (33554432 bytes)
+virtual size: 32 MiB (33554432 bytes)
 cluster_size: 65536
 Format specific information:
     cid: XXXXXXXXXX
@@ -169,7 +169,7 @@ Job failed: List of extents contains unused extents
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 512 (512 bytes)
+virtual size: 512 B (512 bytes)
 Format specific information:
     cid: XXXXXXXXXX
     parent cid: XXXXXXXXXX
@@ -189,7 +189,7 @@ Format specific information:
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 512 (512 bytes)
+virtual size: 512 B (512 bytes)
 cluster_size: 65536
 Format specific information:
     cid: XXXXXXXXXX
@@ -211,7 +211,7 @@ Format specific information:
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 1.0G (1073741824 bytes)
+virtual size: 1 GiB (1073741824 bytes)
 Format specific information:
     cid: XXXXXXXXXX
     parent cid: XXXXXXXXXX
@@ -231,7 +231,7 @@ Format specific information:
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 1.0G (1073741824 bytes)
+virtual size: 1 GiB (1073741824 bytes)
 cluster_size: 65536
 Format specific information:
     cid: XXXXXXXXXX
@@ -253,7 +253,7 @@ Format specific information:
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 2.0G (2147483648 bytes)
+virtual size: 2 GiB (2147483648 bytes)
 Format specific information:
     cid: XXXXXXXXXX
     parent cid: XXXXXXXXXX
@@ -273,7 +273,7 @@ Format specific information:
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 2.0G (2147483648 bytes)
+virtual size: 2 GiB (2147483648 bytes)
 cluster_size: 65536
 Format specific information:
     cid: XXXXXXXXXX
@@ -295,7 +295,7 @@ Format specific information:
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 5.0G (5368709120 bytes)
+virtual size: 5 GiB (5368709120 bytes)
 Format specific information:
     cid: XXXXXXXXXX
     parent cid: XXXXXXXXXX
@@ -323,7 +323,7 @@ Format specific information:
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 5.0G (5368709120 bytes)
+virtual size: 5 GiB (5368709120 bytes)
 cluster_size: 65536
 Format specific information:
     cid: XXXXXXXXXX
diff --git a/tests/qemu-iotests/242.out b/tests/qemu-iotests/242.out
index fbe05d71c0..7ac8404d11 100644
--- a/tests/qemu-iotests/242.out
+++ b/tests/qemu-iotests/242.out
@@ -8,7 +8,7 @@ qemu-img info dump:
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 1.0M (1048576 bytes)
+virtual size: 1 MiB (1048576 bytes)
 cluster_size: 65536
 Format specific information:
     compat: 1.1
@@ -28,7 +28,7 @@ qemu-img info dump:
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 1.0M (1048576 bytes)
+virtual size: 1 MiB (1048576 bytes)
 cluster_size: 65536
 Format specific information:
     compat: 1.1
@@ -60,7 +60,7 @@ qemu-img info dump:
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 1.0M (1048576 bytes)
+virtual size: 1 MiB (1048576 bytes)
 cluster_size: 65536
 Format specific information:
     compat: 1.1
@@ -100,7 +100,7 @@ qemu-img info dump:
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 1.0M (1048576 bytes)
+virtual size: 1 MiB (1048576 bytes)
 cluster_size: 65536
 Format specific information:
     compat: 1.1
@@ -149,7 +149,7 @@ Unset the unknown bitmap flag '0x4' in the bitmap directory entry:
 
 image: TEST_IMG
 file format: IMGFMT
-virtual size: 1.0M (1048576 bytes)
+virtual size: 1 MiB (1048576 bytes)
 cluster_size: 65536
 Format specific information:
     compat: 1.1
diff --git a/tests/qemu-iotests/244.out b/tests/qemu-iotests/244.out
index 98e5946976..6a3d0067cc 100644
--- a/tests/qemu-iotests/244.out
+++ b/tests/qemu-iotests/244.out
@@ -9,22 +9,22 @@ read 65536/65536 bytes at offset 0
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 65536/65536 bytes at offset 0
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-can't open device TEST_DIR/t.qcow2: Could not open 'inexistent': No such file or directory
+qemu-io: can't open device TEST_DIR/t.qcow2: Could not open 'inexistent': No such file or directory
 no file open, try 'help open'
 
 Data file required, but without data file name in the image:
-can't open device TEST_DIR/t.qcow2: 'data-file' is required for this image
+qemu-io: can't open device TEST_DIR/t.qcow2: 'data-file' is required for this image
 no file open, try 'help open'
 read 65536/65536 bytes at offset 0
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-can't open device TEST_DIR/t.qcow2: Could not open 'inexistent': No such file or directory
+qemu-io: can't open device TEST_DIR/t.qcow2: Could not open 'inexistent': No such file or directory
 no file open, try 'help open'
 
 Setting data-file for an image with internal data:
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
-can't open device TEST_DIR/t.qcow2: 'data-file' can only be set for images with an external data file
+qemu-io: can't open device TEST_DIR/t.qcow2: 'data-file' can only be set for images with an external data file
 no file open, try 'help open'
-can't open device TEST_DIR/t.qcow2: Could not open 'inexistent': No such file or directory
+qemu-io: can't open device TEST_DIR/t.qcow2: Could not open 'inexistent': No such file or directory
 no file open, try 'help open'
 
 === Conflicting features ===
diff --git a/tests/qemu-iotests/249 b/tests/qemu-iotests/249
new file mode 100755
index 0000000000..e4650ecf6b
--- /dev/null
+++ b/tests/qemu-iotests/249
@@ -0,0 +1,115 @@
+#!/usr/bin/env bash
+#
+# Test that a backing image is put back in read-only mode after
+# block-commit (both when it fails and when it succeeds).
+#
+# Copyright (C) 2019 Igalia, S.L.
+#
+# 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=berto@igalia.com
+
+seq="$(basename $0)"
+echo "QA output created by $seq"
+
+status=1	# failure is the default!
+
+_cleanup()
+{
+    _cleanup_test_img
+    rm -f "$TEST_IMG.base"
+    rm -f "$TEST_IMG.int"
+}
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+# get standard environment, filters and checks
+. ./common.rc
+. ./common.filter
+. ./common.qemu
+
+# Any format implementing BlockDriver.bdrv_change_backing_file
+_supported_fmt qcow2 qed
+_supported_proto file
+_supported_os Linux
+
+IMG_SIZE=1M
+
+# Create the images: base <- int <- active
+TEST_IMG="$TEST_IMG.base" _make_test_img $IMG_SIZE | _filter_imgfmt
+TEST_IMG="$TEST_IMG.int" _make_test_img -b "$TEST_IMG.base" | _filter_imgfmt
+_make_test_img -b "$TEST_IMG.int" | _filter_imgfmt
+
+# Launch QEMU with these two drives:
+# none0: base (read-only)
+# none1: base <- int <- active
+_launch_qemu -drive if=none,file="${TEST_IMG}.base",node-name=base,read-only=on \
+             -drive if=none,file="${TEST_IMG}",backing.node-name=int,backing.backing=base
+
+_send_qemu_cmd $QEMU_HANDLE \
+    "{ 'execute': 'qmp_capabilities' }" \
+    'return'
+
+echo
+echo '=== Send a write command to a drive opened in read-only mode (1)'
+echo
+_send_qemu_cmd $QEMU_HANDLE \
+    "{ 'execute': 'human-monitor-command',
+       'arguments': {'command-line': 'qemu-io none0 \"aio_write 0 2k\"'}}" \
+    'return'
+
+echo
+echo '=== Run block-commit on base using an invalid filter node name'
+echo
+_send_qemu_cmd $QEMU_HANDLE \
+    "{ 'execute': 'block-commit',
+       'arguments': {'job-id': 'job0', 'device': 'none1', 'top-node': 'int',
+                     'filter-node-name': '1234'}}" \
+    'error'
+
+echo
+echo '=== Send a write command to a drive opened in read-only mode (2)'
+echo
+_send_qemu_cmd $QEMU_HANDLE \
+    "{ 'execute': 'human-monitor-command',
+       'arguments': {'command-line': 'qemu-io none0 \"aio_write 0 2k\"'}}" \
+    'return'
+
+echo
+echo '=== Run block-commit on base using the default filter node name'
+echo
+_send_qemu_cmd $QEMU_HANDLE \
+    "{ 'execute': 'block-commit',
+       'arguments': {'job-id': 'job0', 'device': 'none1', 'top-node': 'int'}}" \
+    'return'
+
+# Wait for block-commit to finish
+_send_qemu_cmd $QEMU_HANDLE '' \
+    '"status": "null"'
+
+echo
+echo '=== Send a write command to a drive opened in read-only mode (3)'
+echo
+_send_qemu_cmd $QEMU_HANDLE \
+    "{ 'execute': 'human-monitor-command',
+       'arguments': {'command-line': 'qemu-io none0 \"aio_write 0 2k\"'}}" \
+    'return'
+
+_cleanup_qemu
+
+# success, all done
+echo "*** done"
+rm -f $seq.full
+status=0
diff --git a/tests/qemu-iotests/249.out b/tests/qemu-iotests/249.out
new file mode 100644
index 0000000000..1c93164e84
--- /dev/null
+++ b/tests/qemu-iotests/249.out
@@ -0,0 +1,35 @@
+QA output created by 249
+Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=1048576
+Formatting 'TEST_DIR/t.IMGFMT.int', fmt=IMGFMT size=1048576 backing_file=TEST_DIR/t.IMGFMT.base
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1048576 backing_file=TEST_DIR/t.IMGFMT.int
+{"return": {}}
+
+=== Send a write command to a drive opened in read-only mode (1)
+
+{"return": "Block node is read-onlyrn"}
+
+=== Run block-commit on base using an invalid filter node name
+
+{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "created", "id": "job0"}}
+{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "null", "id": "job0"}}
+{"error": {"class": "GenericError", "desc": "Invalid node name"}}
+
+=== Send a write command to a drive opened in read-only mode (2)
+
+{"return": "Block node is read-onlyrn"}
+
+=== Run block-commit on base using the default filter node name
+
+{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "created", "id": "job0"}}
+{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "running", "id": "job0"}}
+{"return": {}}
+{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "waiting", "id": "job0"}}
+{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "pending", "id": "job0"}}
+{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_COMPLETED", "data": {"device": "job0", "len": 1048576, "offset": 1048576, "speed": 0, "type": "commit"}}
+{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "concluded", "id": "job0"}}
+{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "null", "id": "job0"}}
+
+=== Send a write command to a drive opened in read-only mode (3)
+
+{"return": "Block node is read-onlyrn"}
+*** done
diff --git a/tests/qemu-iotests/group b/tests/qemu-iotests/group
index bae7718380..7ac9a5ea4a 100644
--- a/tests/qemu-iotests/group
+++ b/tests/qemu-iotests/group
@@ -248,3 +248,4 @@
 246 rw auto quick
 247 rw auto quick
 248 rw auto quick
+249 rw auto quick
diff --git a/util/cutils.c b/util/cutils.c
index e098debdc0..d682c90901 100644
--- a/util/cutils.c
+++ b/util/cutils.c
@@ -825,7 +825,7 @@ const char *qemu_ether_ntoa(const MACAddr *mac)
 char *size_to_str(uint64_t val)
 {
     static const char *suffixes[] = { "", "Ki", "Mi", "Gi", "Ti", "Pi", "Ei" };
-    unsigned long div;
+    uint64_t div;
     int i;
 
     /*