diff --git a/block.c b/block.c
index 163457f..55100e2 100644
--- a/block.c
+++ b/block.c
@@ -679,7 +679,6 @@ static void bdrv_temp_snapshot_options(int *child_flags, QDict *child_options,
     *child_flags = (parent_flags & ~BDRV_O_SNAPSHOT) | BDRV_O_TEMPORARY;
 
     /* For temporary files, unconditional cache=unsafe is fine */
-    qdict_set_default_str(child_options, BDRV_OPT_CACHE_WB, "on");
     qdict_set_default_str(child_options, BDRV_OPT_CACHE_DIRECT, "off");
     qdict_set_default_str(child_options, BDRV_OPT_CACHE_NO_FLUSH, "on");
 }
@@ -704,7 +703,6 @@ static void bdrv_inherited_options(int *child_flags, QDict *child_options,
     /* Our block drivers take care to send flushes and respect unmap policy,
      * so we can default to enable both on lower layers regardless of the
      * corresponding parent options. */
-    qdict_set_default_str(child_options, BDRV_OPT_CACHE_WB, "on");
     flags |= BDRV_O_UNMAP;
 
     /* Clear flags that only apply to the top layer */
@@ -747,7 +745,6 @@ static void bdrv_backing_options(int *child_flags, QDict *child_options,
 
     /* The cache mode is inherited unmodified for backing files; except WCE,
      * which is only applied on the top level (BlockBackend) */
-    qdict_set_default_str(child_options, BDRV_OPT_CACHE_WB, "on");
     qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_DIRECT);
     qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_NO_FLUSH);
 
@@ -766,7 +763,7 @@ static const BdrvChildRole child_backing = {
 
 static int bdrv_open_flags(BlockDriverState *bs, int flags)
 {
-    int open_flags = flags | BDRV_O_CACHE_WB;
+    int open_flags = flags;
 
     /*
      * Clear flags that are internal to the block layer before opening the
@@ -788,11 +785,6 @@ static void update_flags_from_options(int *flags, QemuOpts *opts)
 {
     *flags &= ~BDRV_O_CACHE_MASK;
 
-    assert(qemu_opt_find(opts, BDRV_OPT_CACHE_WB));
-    if (qemu_opt_get_bool(opts, BDRV_OPT_CACHE_WB, false)) {
-        *flags |= BDRV_O_CACHE_WB;
-    }
-
     assert(qemu_opt_find(opts, BDRV_OPT_CACHE_NO_FLUSH));
     if (qemu_opt_get_bool(opts, BDRV_OPT_CACHE_NO_FLUSH, false)) {
         *flags |= BDRV_O_NO_FLUSH;
@@ -806,10 +798,6 @@ static void update_flags_from_options(int *flags, QemuOpts *opts)
 
 static void update_options_from_flags(QDict *options, int flags)
 {
-    if (!qdict_haskey(options, BDRV_OPT_CACHE_WB)) {
-        qdict_put(options, BDRV_OPT_CACHE_WB,
-                  qbool_from_bool(flags & BDRV_O_CACHE_WB));
-    }
     if (!qdict_haskey(options, BDRV_OPT_CACHE_DIRECT)) {
         qdict_put(options, BDRV_OPT_CACHE_DIRECT,
                   qbool_from_bool(flags & BDRV_O_NOCACHE));
@@ -872,11 +860,6 @@ static QemuOptsList bdrv_runtime_opts = {
             .help = "Block driver to use for the node",
         },
         {
-            .name = BDRV_OPT_CACHE_WB,
-            .type = QEMU_OPT_BOOL,
-            .help = "Enable writeback mode",
-        },
-        {
             .name = BDRV_OPT_CACHE_DIRECT,
             .type = QEMU_OPT_BOOL,
             .help = "Bypass software writeback cache on the host",
@@ -983,14 +966,6 @@ static int bdrv_open_common(BlockDriverState *bs, BdrvChild *file,
     /* Apply cache mode options */
     update_flags_from_options(&bs->open_flags, opts);
 
-    if (!bs->blk && (bs->open_flags & BDRV_O_CACHE_WB) == 0) {
-        error_setg(errp, "Can't set writethrough mode except for the root");
-        ret = -EINVAL;
-        goto free_and_fail;
-    }
-
-    bdrv_set_enable_write_cache(bs, bs->open_flags & BDRV_O_CACHE_WB);
-
     /* Open the image, either directly or using a protocol */
     open_flags = bdrv_open_flags(bs, bs->open_flags);
     if (drv->bdrv_file_open) {
@@ -2012,16 +1987,6 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue,
 
     update_flags_from_options(&reopen_state->flags, opts);
 
-    /* WCE is a BlockBackend level option, can't change it */
-    bool old_wce = bdrv_enable_write_cache(reopen_state->bs);
-    bool new_wce = (reopen_state->flags & BDRV_O_CACHE_WB);
-
-    if (old_wce != new_wce) {
-        error_setg(errp, "Cannot change cache.writeback");
-        ret = -EINVAL;
-        goto error;
-    }
-
     /* node-name and driver must be unchanged. Put them back into the QDict, so
      * that they are checked at the end of this function. */
     value = qemu_opt_get(opts, "node-name");
@@ -2123,8 +2088,6 @@ void bdrv_reopen_commit(BDRVReopenState *reopen_state)
     reopen_state->bs->open_flags         = reopen_state->flags;
     reopen_state->bs->read_only = !(reopen_state->flags & BDRV_O_RDWR);
 
-    bdrv_set_enable_write_cache(reopen_state->bs,
-                                !!(reopen_state->flags & BDRV_O_CACHE_WB));
     bdrv_refresh_limits(reopen_state->bs, NULL);
 }
 
@@ -2745,13 +2708,6 @@ void bdrv_set_enable_write_cache(BlockDriverState *bs, bool wce)
     if (bs->blk) {
         blk_set_enable_write_cache(bs->blk, wce);
     }
-
-    /* so a reopen() will preserve wce */
-    if (wce) {
-        bs->open_flags |= BDRV_O_CACHE_WB;
-    } else {
-        bs->open_flags &= ~BDRV_O_CACHE_WB;
-    }
 }
 
 int bdrv_is_encrypted(BlockDriverState *bs)
@@ -3604,7 +3560,7 @@ void bdrv_img_create(const char *filename, const char *fmt,
             }
 
             /* backing files always opened read-only */
-            back_flags = flags | BDRV_O_CACHE_WB;
+            back_flags = flags;
             back_flags &= ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING);
 
             if (backing_fmt) {
diff --git a/block/block-backend.c b/block/block-backend.c
index 23f2c27..a528674 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -149,8 +149,6 @@ BlockBackend *blk_new_open(const char *filename, const char *reference,
     BlockBackend *blk;
     int ret;
 
-    assert((flags & BDRV_O_CACHE_WB) == 0);
-
     blk = blk_new_with_bs(errp);
     if (!blk) {
         QDECREF(options);
@@ -1223,15 +1221,6 @@ int blk_enable_write_cache(BlockBackend *blk)
 void blk_set_enable_write_cache(BlockBackend *blk, bool wce)
 {
     blk->enable_write_cache = wce;
-
-    /* TODO Remove this when BDRV_O_CACHE_WB isn't used any more */
-    if (blk->root) {
-        if (wce) {
-            blk->root->bs->open_flags |= BDRV_O_CACHE_WB;
-        } else {
-            blk->root->bs->open_flags &= ~BDRV_O_CACHE_WB;
-        }
-    }
 }
 
 void blk_invalidate_cache(BlockBackend *blk, Error **errp)
diff --git a/block/vvfat.c b/block/vvfat.c
index b8d29e1..d5dbb89 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -2956,8 +2956,7 @@ static int enable_write_target(BDRVVVFATState *s, Error **errp)
     options = qdict_new();
     qdict_put(options, "driver", qstring_from_str("qcow"));
     ret = bdrv_open(&s->qcow, s->qcow_filename, NULL, options,
-                    BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_NO_FLUSH,
-                    errp);
+                    BDRV_O_RDWR | BDRV_O_NO_FLUSH, errp);
     if (ret < 0) {
         goto err;
     }
diff --git a/blockdev.c b/blockdev.c
index c2dd584..5a53f59 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -593,7 +593,6 @@ static BlockBackend *blockdev_init(const char *file, QDict *bs_opts,
         /* bdrv_open() defaults to the values in bdrv_flags (for compatibility
          * with other callers) rather than what we want as the real defaults.
          * Apply the defaults here instead. */
-        qdict_set_default_str(bs_opts, BDRV_OPT_CACHE_WB, writethrough ? "off" : "on");
         qdict_set_default_str(bs_opts, BDRV_OPT_CACHE_DIRECT, "off");
         qdict_set_default_str(bs_opts, BDRV_OPT_CACHE_NO_FLUSH, "off");
         assert((bdrv_flags & BDRV_O_CACHE_MASK) == 0);
@@ -689,7 +688,6 @@ static BlockDriverState *bds_tree_init(QDict *bs_opts, Error **errp)
     /* bdrv_open() defaults to the values in bdrv_flags (for compatibility
      * with other callers) rather than what we want as the real defaults.
      * Apply the defaults here instead. */
-    qdict_set_default_str(bs_opts, BDRV_OPT_CACHE_WB, "on");
     qdict_set_default_str(bs_opts, BDRV_OPT_CACHE_DIRECT, "off");
     qdict_set_default_str(bs_opts, BDRV_OPT_CACHE_NO_FLUSH, "off");
 
@@ -1777,12 +1775,6 @@ static void external_snapshot_prepare(BlkActionState *common,
         flags |= BDRV_O_NO_BACKING;
     }
 
-    /* There is no BB attached during bdrv_open(), so we can't set a
-     * writethrough mode. bdrv_append() will swap the WCE setting so that the
-     * backing file becomes unconditionally writeback (which is what backing
-     * files should always be) and the new overlay gets the original setting. */
-    flags |= BDRV_O_CACHE_WB;
-
     assert(state->new_bs == NULL);
     ret = bdrv_open(&state->new_bs, new_image_file, snapshot_ref, options,
                     flags, errp);
@@ -2527,7 +2519,6 @@ void qmp_blockdev_change_medium(const char *device, const char *filename,
     BlockBackend *blk;
     BlockDriverState *medium_bs = NULL;
     int bdrv_flags, ret;
-    bool writethrough;
     QDict *options = NULL;
     Error *err = NULL;
 
@@ -2546,12 +2537,6 @@ void qmp_blockdev_change_medium(const char *device, const char *filename,
     bdrv_flags &= ~(BDRV_O_TEMPORARY | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING |
         BDRV_O_PROTOCOL);
 
-    /* Must open the image in writeback mode as long as no BlockBackend is
-     * attached. The right mode can be set as the final step after changing the
-     * medium. */
-    writethrough = !(bdrv_flags & BDRV_O_CACHE_WB);
-    bdrv_flags |= BDRV_O_CACHE_WB;
-
     if (!has_read_only) {
         read_only = BLOCKDEV_CHANGE_READ_ONLY_MODE_RETAIN;
     }
@@ -2609,8 +2594,6 @@ void qmp_blockdev_change_medium(const char *device, const char *filename,
         goto fail;
     }
 
-    bdrv_set_enable_write_cache(medium_bs, !writethrough);
-
     qmp_blockdev_close_tray(device, errp);
 
 fail:
@@ -3236,7 +3219,7 @@ static void do_drive_backup(const char *device, const char *target,
         goto out;
     }
 
-    flags = bs->open_flags | BDRV_O_CACHE_WB | BDRV_O_RDWR;
+    flags = bs->open_flags | BDRV_O_RDWR;
 
     /* See if we have a backing HD we can use to create our new image
      * on top of. */
@@ -3531,7 +3514,7 @@ void qmp_drive_mirror(const char *device, const char *target,
         format = mode == NEW_IMAGE_MODE_EXISTING ? NULL : bs->drv->format_name;
     }
 
-    flags = bs->open_flags | BDRV_O_CACHE_WB | BDRV_O_RDWR;
+    flags = bs->open_flags | BDRV_O_RDWR;
     source = backing_bs(bs);
     if (!source && sync == MIRROR_SYNC_MODE_TOP) {
         sync = MIRROR_SYNC_MODE_FULL;
diff --git a/include/block/block.h b/include/block/block.h
index db1b997..bd8fa21 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -82,7 +82,6 @@ typedef struct HDGeometry {
 #define BDRV_O_SNAPSHOT    0x0008 /* open the file read only and save writes in a snapshot */
 #define BDRV_O_TEMPORARY   0x0010 /* delete the file after use */
 #define BDRV_O_NOCACHE     0x0020 /* do not use the host page cache */
-#define BDRV_O_CACHE_WB    0x0040 /* use write-back caching */
 #define BDRV_O_NATIVE_AIO  0x0080 /* use native AIO instead of the thread pool */
 #define BDRV_O_NO_BACKING  0x0100 /* don't open the backing file */
 #define BDRV_O_NO_FLUSH    0x0200 /* disable flushing on this disk */
@@ -96,7 +95,7 @@ typedef struct HDGeometry {
                                       ignoring the format layer */
 #define BDRV_O_NO_IO       0x10000 /* don't initialize for I/O */
 
-#define BDRV_O_CACHE_MASK  (BDRV_O_NOCACHE | BDRV_O_CACHE_WB | BDRV_O_NO_FLUSH)
+#define BDRV_O_CACHE_MASK  (BDRV_O_NOCACHE | BDRV_O_NO_FLUSH)
 
 
 /* Option names of options parsed by the block layer */
diff --git a/qemu-img.c b/qemu-img.c
index 1be3652..500eadb 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -462,7 +462,7 @@ static int img_create(int argc, char **argv)
     }
 
     bdrv_img_create(filename, fmt, base_filename, base_fmt,
-                    options, img_size, BDRV_O_CACHE_WB, &local_err, quiet);
+                    options, img_size, 0, &local_err, quiet);
     if (local_err) {
         error_reportf_err(local_err, "%s: ", filename);
         goto fail;
diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c
index 7de3754..35ee50b 100644
--- a/qemu-io-cmds.c
+++ b/qemu-io-cmds.c
@@ -2149,7 +2149,6 @@ static int reopen_f(BlockBackend *blk, int argc, char **argv)
     opts = qopts ? qemu_opts_to_qdict(qopts, NULL) : NULL;
     qemu_opts_reset(&reopen_opts);
 
-    flags |= blk_enable_write_cache(blk) ? BDRV_O_CACHE_WB : 0;
     brq = bdrv_reopen_queue(NULL, bs, opts, flags);
     bdrv_reopen_multiple(brq, &local_err);
     if (local_err) {
diff --git a/tests/qemu-iotests/051 b/tests/qemu-iotests/051
index 7bfe9ff..88b3d91 100755
--- a/tests/qemu-iotests/051
+++ b/tests/qemu-iotests/051
@@ -218,7 +218,7 @@ run_qemu -drive driver=null-co,cache=invalid_value
 
 for cache in writeback writethrough unsafe invalid_value; do
     echo -e "info block\ninfo block file\ninfo block backing\ninfo block backing-file" | \
-    run_qemu -drive file="$TEST_IMG",cache=$cache,backing.file.filename="$TEST_IMG.base",backing.cache.no-flush=on,backing.cache.writeback=on,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,if=none,id=$device_id -nodefaults
+    run_qemu -drive file="$TEST_IMG",cache=$cache,backing.file.filename="$TEST_IMG.base",backing.cache.no-flush=on,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,if=none,id=$device_id -nodefaults
 done
 
 echo
diff --git a/tests/qemu-iotests/051.pc.out b/tests/qemu-iotests/051.pc.out
index 73cc15a..ec6d222 100644
--- a/tests/qemu-iotests/051.pc.out
+++ b/tests/qemu-iotests/051.pc.out
@@ -239,7 +239,7 @@ QEMU X.Y.Z monitor - type 'help' for more information
 Testing: -drive driver=null-co,cache=invalid_value
 QEMU_PROG: -drive driver=null-co,cache=invalid_value: invalid cache option
 
-Testing: -drive file=TEST_DIR/t.qcow2,cache=writeback,backing.file.filename=TEST_DIR/t.qcow2.base,backing.cache.no-flush=on,backing.cache.writeback=on,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,if=none,id=drive0 -nodefaults
+Testing: -drive file=TEST_DIR/t.qcow2,cache=writeback,backing.file.filename=TEST_DIR/t.qcow2.base,backing.cache.no-flush=on,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,if=none,id=drive0 -nodefaults
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) i[K[Din[K[D[Dinf[K[D[D[Dinfo[K[D[D[D[Dinfo [K[D[D[D[D[Dinfo b[K[D[D[D[D[D[Dinfo bl[K[D[D[D[D[D[D[Dinfo blo[K[D[D[D[D[D[D[D[Dinfo bloc[K[D[D[D[D[D[D[D[D[Dinfo block[K
 drive0 (NODE_NAME): TEST_DIR/t.qcow2 (qcow2)
@@ -259,7 +259,7 @@ backing-file: TEST_DIR/t.qcow2.base (file, read-only)
     Cache mode:       writeback, ignore flushes
 (qemu) q[K[Dqu[K[D[Dqui[K[D[D[Dquit[K
 
-Testing: -drive file=TEST_DIR/t.qcow2,cache=writethrough,backing.file.filename=TEST_DIR/t.qcow2.base,backing.cache.no-flush=on,backing.cache.writeback=on,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,if=none,id=drive0 -nodefaults
+Testing: -drive file=TEST_DIR/t.qcow2,cache=writethrough,backing.file.filename=TEST_DIR/t.qcow2.base,backing.cache.no-flush=on,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,if=none,id=drive0 -nodefaults
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) i[K[Din[K[D[Dinf[K[D[D[Dinfo[K[D[D[D[Dinfo [K[D[D[D[D[Dinfo b[K[D[D[D[D[D[Dinfo bl[K[D[D[D[D[D[D[Dinfo blo[K[D[D[D[D[D[D[D[Dinfo bloc[K[D[D[D[D[D[D[D[D[Dinfo block[K
 drive0 (NODE_NAME): TEST_DIR/t.qcow2 (qcow2)
@@ -279,7 +279,7 @@ backing-file: TEST_DIR/t.qcow2.base (file, read-only)
     Cache mode:       writeback, ignore flushes
 (qemu) q[K[Dqu[K[D[Dqui[K[D[D[Dquit[K
 
-Testing: -drive file=TEST_DIR/t.qcow2,cache=unsafe,backing.file.filename=TEST_DIR/t.qcow2.base,backing.cache.no-flush=on,backing.cache.writeback=on,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,if=none,id=drive0 -nodefaults
+Testing: -drive file=TEST_DIR/t.qcow2,cache=unsafe,backing.file.filename=TEST_DIR/t.qcow2.base,backing.cache.no-flush=on,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,if=none,id=drive0 -nodefaults
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) i[K[Din[K[D[Dinf[K[D[D[Dinfo[K[D[D[D[Dinfo [K[D[D[D[D[Dinfo b[K[D[D[D[D[D[Dinfo bl[K[D[D[D[D[D[D[Dinfo blo[K[D[D[D[D[D[D[D[Dinfo bloc[K[D[D[D[D[D[D[D[D[Dinfo block[K
 drive0 (NODE_NAME): TEST_DIR/t.qcow2 (qcow2)
@@ -299,8 +299,8 @@ backing-file: TEST_DIR/t.qcow2.base (file, read-only)
     Cache mode:       writeback, ignore flushes
 (qemu) q[K[Dqu[K[D[Dqui[K[D[D[Dquit[K
 
-Testing: -drive file=TEST_DIR/t.qcow2,cache=invalid_value,backing.file.filename=TEST_DIR/t.qcow2.base,backing.cache.no-flush=on,backing.cache.writeback=on,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,if=none,id=drive0 -nodefaults
-QEMU_PROG: -drive file=TEST_DIR/t.qcow2,cache=invalid_value,backing.file.filename=TEST_DIR/t.qcow2.base,backing.cache.no-flush=on,backing.cache.writeback=on,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,if=none,id=drive0: invalid cache option
+Testing: -drive file=TEST_DIR/t.qcow2,cache=invalid_value,backing.file.filename=TEST_DIR/t.qcow2.base,backing.cache.no-flush=on,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,if=none,id=drive0 -nodefaults
+QEMU_PROG: -drive file=TEST_DIR/t.qcow2,cache=invalid_value,backing.file.filename=TEST_DIR/t.qcow2.base,backing.cache.no-flush=on,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,if=none,id=drive0: invalid cache option
 
 
 === Specifying the protocol layer ===
diff --git a/tests/qemu-iotests/142 b/tests/qemu-iotests/142
index a035747..3828c23 100755
--- a/tests/qemu-iotests/142
+++ b/tests/qemu-iotests/142
@@ -110,11 +110,11 @@ function check_cache_all()
     echo -e "\n\ncache.writeback=off on none0"
     echo "$hmp_cmds" | run_qemu -drive "$files","$ids",cache.writeback=off | grep -e "Cache" -e "[Cc]annot\|[Cc]ould not\|[Cc]an't"
     echo -e "\ncache.writeback=off on file"
-    echo "$hmp_cmds" | run_qemu -drive "$files","$ids",file.cache.writeback=off | grep -e "Cache" -e "[Cc]annot\|[Cc]ould not\|[Cc]an't"
+    echo "$hmp_cmds" | run_qemu -drive "$files","$ids",file.cache.writeback=off | grep -e "doesn't" -e "does not"
     echo -e "\ncache.writeback=off on backing"
-    echo "$hmp_cmds" | run_qemu -drive "$files","$ids",backing.cache.writeback=off | grep -e "Cache" -e "[Cc]annot\|[Cc]ould not\|[Cc]an't"
+    echo "$hmp_cmds" | run_qemu -drive "$files","$ids",backing.cache.writeback=off | grep -e "doesn't" -e "does not"
     echo -e "\ncache.writeback=off on backing-file"
-    echo "$hmp_cmds" | run_qemu -drive "$files","$ids",backing.file.cache.writeback=off | grep -e "Cache" -e "[Cc]annot\|[Cc]ould not\|[Cc]an't"
+    echo "$hmp_cmds" | run_qemu -drive "$files","$ids",backing.file.cache.writeback=off | grep -e "doesn't" -e "does not"
 
     # cache.no-flush is supposed to be inherited by both bs->file and bs->backing
 
diff --git a/tests/qemu-iotests/142.out b/tests/qemu-iotests/142.out
index 3d5ef5f..600beca 100644
--- a/tests/qemu-iotests/142.out
+++ b/tests/qemu-iotests/142.out
@@ -71,13 +71,13 @@ cache.writeback=off on none0
     Cache mode:       writeback
 
 cache.writeback=off on file
-QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,file.cache.writeback=off: Can't set writethrough mode except for the root
+QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,file.cache.writeback=off: Block protocol 'file' doesn't support the option 'cache.writeback'
 
 cache.writeback=off on backing
-QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,backing.cache.writeback=off: Could not open backing file: Can't set writethrough mode except for the root
+QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,backing.cache.writeback=off: Could not open backing file: Block format 'qcow2' does not support the option 'cache.writeback'
 
 cache.writeback=off on backing-file
-QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,backing.file.cache.writeback=off: Could not open backing file: Can't set writethrough mode except for the root
+QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,backing.file.cache.writeback=off: Could not open backing file: Block protocol 'file' doesn't support the option 'cache.writeback'
 
 
 cache.no-flush=on on none0
@@ -147,13 +147,13 @@ cache.writeback=off on none0
     Cache mode:       writeback
 
 cache.writeback=off on file
-QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,file.cache.writeback=off: Can't set writethrough mode except for the root
+QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,file.cache.writeback=off: Block protocol 'file' doesn't support the option 'cache.writeback'
 
 cache.writeback=off on backing
-QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,backing.cache.writeback=off: Could not open backing file: Can't set writethrough mode except for the root
+QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,backing.cache.writeback=off: Could not open backing file: Block format 'qcow2' does not support the option 'cache.writeback'
 
 cache.writeback=off on backing-file
-QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,backing.file.cache.writeback=off: Could not open backing file: Can't set writethrough mode except for the root
+QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,backing.file.cache.writeback=off: Could not open backing file: Block protocol 'file' doesn't support the option 'cache.writeback'
 
 
 cache.no-flush=on on none0
@@ -223,13 +223,13 @@ cache.writeback=off on none0
     Cache mode:       writeback, direct
 
 cache.writeback=off on file
-QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,file.cache.writeback=off: Can't set writethrough mode except for the root
+QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,file.cache.writeback=off: Block protocol 'file' doesn't support the option 'cache.writeback'
 
 cache.writeback=off on backing
-QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,backing.cache.writeback=off: Could not open backing file: Can't set writethrough mode except for the root
+QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,backing.cache.writeback=off: Could not open backing file: Block format 'qcow2' does not support the option 'cache.writeback'
 
 cache.writeback=off on backing-file
-QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,backing.file.cache.writeback=off: Could not open backing file: Can't set writethrough mode except for the root
+QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,backing.file.cache.writeback=off: Could not open backing file: Block protocol 'file' doesn't support the option 'cache.writeback'
 
 
 cache.no-flush=on on none0
@@ -299,13 +299,13 @@ cache.writeback=off on none0
     Cache mode:       writeback, direct
 
 cache.writeback=off on file
-QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,file.cache.writeback=off: Can't set writethrough mode except for the root
+QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,file.cache.writeback=off: Block protocol 'file' doesn't support the option 'cache.writeback'
 
 cache.writeback=off on backing
-QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,backing.cache.writeback=off: Could not open backing file: Can't set writethrough mode except for the root
+QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,backing.cache.writeback=off: Could not open backing file: Block format 'qcow2' does not support the option 'cache.writeback'
 
 cache.writeback=off on backing-file
-QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,backing.file.cache.writeback=off: Could not open backing file: Can't set writethrough mode except for the root
+QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,backing.file.cache.writeback=off: Could not open backing file: Block protocol 'file' doesn't support the option 'cache.writeback'
 
 
 cache.no-flush=on on none0
@@ -375,13 +375,13 @@ cache.writeback=off on none0
     Cache mode:       writeback
 
 cache.writeback=off on file
-QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,file.cache.writeback=off: Can't set writethrough mode except for the root
+QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,file.cache.writeback=off: Block protocol 'file' doesn't support the option 'cache.writeback'
 
 cache.writeback=off on backing
-QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,backing.cache.writeback=off: Could not open backing file: Can't set writethrough mode except for the root
+QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,backing.cache.writeback=off: Could not open backing file: Block format 'qcow2' does not support the option 'cache.writeback'
 
 cache.writeback=off on backing-file
-QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,backing.file.cache.writeback=off: Could not open backing file: Can't set writethrough mode except for the root
+QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,backing.file.cache.writeback=off: Could not open backing file: Block protocol 'file' doesn't support the option 'cache.writeback'
 
 
 cache.no-flush=on on none0
@@ -704,13 +704,13 @@ cache.writeback=off on none0
     Cache mode:       writeback, direct
 
 cache.writeback=off on file
-QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,file.cache.writeback=off: Can't set writethrough mode except for the root
+QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,file.cache.writeback=off: Block protocol 'file' doesn't support the option 'cache.writeback'
 
 cache.writeback=off on backing
-QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,backing.cache.writeback=off: Could not open backing file: Can't set writethrough mode except for the root
+QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,backing.cache.writeback=off: Could not open backing file: Block format 'qcow2' does not support the option 'cache.writeback'
 
 cache.writeback=off on backing-file
-QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,backing.file.cache.writeback=off: Could not open backing file: Can't set writethrough mode except for the root
+QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2,backing.file.filename=TEST_DIR/t.qcow2.base,node-name=image,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,backing.file.cache.writeback=off: Could not open backing file: Block protocol 'file' doesn't support the option 'cache.writeback'
 
 
 cache.no-flush=on on none0
