Merge remote-tracking branch 'remotes/maxreitz/tags/pull-block-2019-08-19' into staging

Block patches:
- preallocation=falloc/full support for LUKS
- Various minor fixes

# gpg: Signature made Mon 19 Aug 2019 16:36:45 BST
# gpg:                using RSA key 91BEB60A30DB3E8857D11829F407DB0061D5CF40
# gpg:                issuer "mreitz@redhat.com"
# gpg: Good signature from "Max Reitz <mreitz@redhat.com>" [full]
# Primary key fingerprint: 91BE B60A 30DB 3E88 57D1  1829 F407 DB00 61D5 CF40

* remotes/maxreitz/tags/pull-block-2019-08-19:
  doc: Preallocation does not require writing zeroes
  iotests: Fix 141 when run with qed
  vpc: Do not return RAW from block_status
  vmdk: Make block_status recurse for flat extents
  vdi: Make block_status recurse for fixed images
  iotests: Full mirror to existing non-zero image
  iotests: Test convert -n to pre-filled image
  iotests: Convert to preallocated encrypted qcow2
  vhdx: Fix .bdrv_has_zero_init()
  vdi: Fix .bdrv_has_zero_init()
  qcow2: Fix .bdrv_has_zero_init()
  block: Use bdrv_has_zero_init_truncate()
  block: Implement .bdrv_has_zero_init_truncate()
  block: Add bdrv_has_zero_init_truncate()
  mirror: Fix bdrv_has_zero_init() use
  qemu-img: Fix bdrv_has_zero_init() use in convert
  LUKS: support preallocation

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

35 files changed, 313 insertions, 43 deletions

diff --git a/block.c b/block.c
index 3e698e9..874a29a 100644
--- a/block.c
+++ b/block.c
@@ -5078,6 +5078,27 @@ int bdrv_has_zero_init(BlockDriverState *bs)
     return 0;
 }
 
+int bdrv_has_zero_init_truncate(BlockDriverState *bs)
+{
+    if (!bs->drv) {
+        return 0;
+    }
+
+    if (bs->backing) {
+        /* Depends on the backing image length, but better safe than sorry */
+        return 0;
+    }
+    if (bs->drv->bdrv_has_zero_init_truncate) {
+        return bs->drv->bdrv_has_zero_init_truncate(bs);
+    }
+    if (bs->file && bs->drv->is_filter) {
+        return bdrv_has_zero_init_truncate(bs->file->bs);
+    }
+
+    /* safe default */
+    return 0;
+}
+
 bool bdrv_unallocated_blocks_are_zero(BlockDriverState *bs)
 {
     BlockDriverInfo bdi;
diff --git a/block/crypto.c b/block/crypto.c
index 8237424..7eb6987 100644
--- a/block/crypto.c
+++ b/block/crypto.c
@@ -74,6 +74,7 @@ static ssize_t block_crypto_read_func(QCryptoBlock *block,
 struct BlockCryptoCreateData {
     BlockBackend *blk;
     uint64_t size;
+    PreallocMode prealloc;
 };
 
 
@@ -112,7 +113,7 @@ static ssize_t block_crypto_init_func(QCryptoBlock *block,
      * available to the guest, so we must take account of that
      * which will be used by the crypto header
      */
-    return blk_truncate(data->blk, data->size + headerlen, PREALLOC_MODE_OFF,
+    return blk_truncate(data->blk, data->size + headerlen, data->prealloc,
                         errp);
 }
 
@@ -251,6 +252,7 @@ static int block_crypto_open_generic(QCryptoBlockFormat format,
 static int block_crypto_co_create_generic(BlockDriverState *bs,
                                           int64_t size,
                                           QCryptoBlockCreateOptions *opts,
+                                          PreallocMode prealloc,
                                           Error **errp)
 {
     int ret;
@@ -266,9 +268,14 @@ static int block_crypto_co_create_generic(BlockDriverState *bs,
         goto cleanup;
     }
 
+    if (prealloc == PREALLOC_MODE_METADATA) {
+        prealloc = PREALLOC_MODE_OFF;
+    }
+
     data = (struct BlockCryptoCreateData) {
         .blk = blk,
         .size = size,
+        .prealloc = prealloc,
     };
 
     crypto = qcrypto_block_create(opts, NULL,
@@ -500,6 +507,7 @@ block_crypto_co_create_luks(BlockdevCreateOptions *create_options, Error **errp)
     BlockdevCreateOptionsLUKS *luks_opts;
     BlockDriverState *bs = NULL;
     QCryptoBlockCreateOptions create_opts;
+    PreallocMode preallocation = PREALLOC_MODE_OFF;
     int ret;
 
     assert(create_options->driver == BLOCKDEV_DRIVER_LUKS);
@@ -515,8 +523,12 @@ block_crypto_co_create_luks(BlockdevCreateOptions *create_options, Error **errp)
         .u.luks = *qapi_BlockdevCreateOptionsLUKS_base(luks_opts),
     };
 
+    if (luks_opts->has_preallocation) {
+        preallocation = luks_opts->preallocation;
+    }
+
     ret = block_crypto_co_create_generic(bs, luks_opts->size, &create_opts,
-                                         errp);
+                                         preallocation, errp);
     if (ret < 0) {
         goto fail;
     }
@@ -534,12 +546,24 @@ static int coroutine_fn block_crypto_co_create_opts_luks(const char *filename,
     QCryptoBlockCreateOptions *create_opts = NULL;
     BlockDriverState *bs = NULL;
     QDict *cryptoopts;
+    PreallocMode prealloc;
+    char *buf = NULL;
     int64_t size;
     int ret;
+    Error *local_err = NULL;
 
     /* Parse options */
     size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0);
 
+    buf = qemu_opt_get_del(opts, BLOCK_OPT_PREALLOC);
+    prealloc = qapi_enum_parse(&PreallocMode_lookup, buf,
+                               PREALLOC_MODE_OFF, &local_err);
+    g_free(buf);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return -EINVAL;
+    }
+
     cryptoopts = qemu_opts_to_qdict_filtered(opts, NULL,
                                              &block_crypto_create_opts_luks,
                                              true);
@@ -565,7 +589,7 @@ static int coroutine_fn block_crypto_co_create_opts_luks(const char *filename,
     }
 
     /* Create format layer */
-    ret = block_crypto_co_create_generic(bs, size, create_opts, errp);
+    ret = block_crypto_co_create_generic(bs, size, create_opts, prealloc, errp);
     if (ret < 0) {
         goto fail;
     }
diff --git a/block/file-posix.c b/block/file-posix.c
index e41e91e..fbeb006 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -2938,6 +2938,7 @@ BlockDriver bdrv_file = {
     .bdrv_co_create = raw_co_create,
     .bdrv_co_create_opts = raw_co_create_opts,
     .bdrv_has_zero_init = bdrv_has_zero_init_1,
+    .bdrv_has_zero_init_truncate = bdrv_has_zero_init_1,
     .bdrv_co_block_status = raw_co_block_status,
     .bdrv_co_invalidate_cache = raw_co_invalidate_cache,
     .bdrv_co_pwrite_zeroes = raw_co_pwrite_zeroes,
diff --git a/block/file-win32.c b/block/file-win32.c
index 6b2d67b..41f55df 100644
--- a/block/file-win32.c
+++ b/block/file-win32.c
@@ -635,6 +635,7 @@ BlockDriver bdrv_file = {
     .bdrv_close         = raw_close,
     .bdrv_co_create_opts = raw_co_create_opts,
     .bdrv_has_zero_init = bdrv_has_zero_init_1,
+    .bdrv_has_zero_init_truncate = bdrv_has_zero_init_1,
 
     .bdrv_aio_preadv    = raw_aio_preadv,
     .bdrv_aio_pwritev   = raw_aio_pwritev,
diff --git a/block/gluster.c b/block/gluster.c
index f64dc5b..64028b2 100644
--- a/block/gluster.c
+++ b/block/gluster.c
@@ -1567,6 +1567,7 @@ static BlockDriver bdrv_gluster = {
     .bdrv_co_writev               = qemu_gluster_co_writev,
     .bdrv_co_flush_to_disk        = qemu_gluster_co_flush_to_disk,
     .bdrv_has_zero_init           = qemu_gluster_has_zero_init,
+    .bdrv_has_zero_init_truncate  = qemu_gluster_has_zero_init,
 #ifdef CONFIG_GLUSTERFS_DISCARD
     .bdrv_co_pdiscard             = qemu_gluster_co_pdiscard,
 #endif
@@ -1598,6 +1599,7 @@ static BlockDriver bdrv_gluster_tcp = {
     .bdrv_co_writev               = qemu_gluster_co_writev,
     .bdrv_co_flush_to_disk        = qemu_gluster_co_flush_to_disk,
     .bdrv_has_zero_init           = qemu_gluster_has_zero_init,
+    .bdrv_has_zero_init_truncate  = qemu_gluster_has_zero_init,
 #ifdef CONFIG_GLUSTERFS_DISCARD
     .bdrv_co_pdiscard             = qemu_gluster_co_pdiscard,
 #endif
@@ -1629,6 +1631,7 @@ static BlockDriver bdrv_gluster_unix = {
     .bdrv_co_writev               = qemu_gluster_co_writev,
     .bdrv_co_flush_to_disk        = qemu_gluster_co_flush_to_disk,
     .bdrv_has_zero_init           = qemu_gluster_has_zero_init,
+    .bdrv_has_zero_init_truncate  = qemu_gluster_has_zero_init,
 #ifdef CONFIG_GLUSTERFS_DISCARD
     .bdrv_co_pdiscard             = qemu_gluster_co_pdiscard,
 #endif
@@ -1666,6 +1669,7 @@ static BlockDriver bdrv_gluster_rdma = {
     .bdrv_co_writev               = qemu_gluster_co_writev,
     .bdrv_co_flush_to_disk        = qemu_gluster_co_flush_to_disk,
     .bdrv_has_zero_init           = qemu_gluster_has_zero_init,
+    .bdrv_has_zero_init_truncate  = qemu_gluster_has_zero_init,
 #ifdef CONFIG_GLUSTERFS_DISCARD
     .bdrv_co_pdiscard             = qemu_gluster_co_pdiscard,
 #endif
diff --git a/block/mirror.c b/block/mirror.c
index 2b87068..853e2c7 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -51,6 +51,8 @@ typedef struct MirrorBlockJob {
     Error *replace_blocker;
     bool is_none_mode;
     BlockMirrorBackingMode backing_mode;
+    /* Whether the target image requires explicit zero-initialization */
+    bool zero_target;
     MirrorCopyMode copy_mode;
     BlockdevOnError on_source_error, on_target_error;
     bool synced;
@@ -767,7 +769,7 @@ static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s)
     int ret;
     int64_t count;
 
-    if (base == NULL && !bdrv_has_zero_init(target_bs)) {
+    if (s->zero_target) {
         if (!bdrv_can_write_zeroes_with_unmap(target_bs)) {
             bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, s->bdev_length);
             return 0;
@@ -1515,6 +1517,7 @@ static BlockJob *mirror_start_job(
                              const char *replaces, int64_t speed,
                              uint32_t granularity, int64_t buf_size,
                              BlockMirrorBackingMode backing_mode,
+                             bool zero_target,
                              BlockdevOnError on_source_error,
                              BlockdevOnError on_target_error,
                              bool unmap,
@@ -1643,6 +1646,7 @@ static BlockJob *mirror_start_job(
     s->on_target_error = on_target_error;
     s->is_none_mode = is_none_mode;
     s->backing_mode = backing_mode;
+    s->zero_target = zero_target;
     s->copy_mode = copy_mode;
     s->base = base;
     s->granularity = granularity;
@@ -1747,6 +1751,7 @@ void mirror_start(const char *job_id, BlockDriverState *bs,
                   int creation_flags, int64_t speed,
                   uint32_t granularity, int64_t buf_size,
                   MirrorSyncMode mode, BlockMirrorBackingMode backing_mode,
+                  bool zero_target,
                   BlockdevOnError on_source_error,
                   BlockdevOnError on_target_error,
                   bool unmap, const char *filter_node_name,
@@ -1764,7 +1769,7 @@ void mirror_start(const char *job_id, BlockDriverState *bs,
     is_none_mode = mode == MIRROR_SYNC_MODE_NONE;
     base = mode == MIRROR_SYNC_MODE_TOP ? backing_bs(bs) : NULL;
     mirror_start_job(job_id, bs, creation_flags, target, replaces,
-                     speed, granularity, buf_size, backing_mode,
+                     speed, granularity, buf_size, backing_mode, zero_target,
                      on_source_error, on_target_error, unmap, NULL, NULL,
                      &mirror_job_driver, is_none_mode, base, false,
                      filter_node_name, true, copy_mode, errp);
@@ -1791,7 +1796,7 @@ BlockJob *commit_active_start(const char *job_id, BlockDriverState *bs,
 
     ret = mirror_start_job(
                      job_id, bs, creation_flags, base, NULL, speed, 0, 0,
-                     MIRROR_LEAVE_BACKING_CHAIN,
+                     MIRROR_LEAVE_BACKING_CHAIN, false,
                      on_error, on_error, true, cb, opaque,
                      &commit_active_job_driver, false, base, auto_complete,
                      filter_node_name, false, MIRROR_COPY_MODE_BACKGROUND,
diff --git a/block/nfs.c b/block/nfs.c
index ed0cce6..0ec5095 100644
--- a/block/nfs.c
+++ b/block/nfs.c
@@ -863,6 +863,7 @@ static BlockDriver bdrv_nfs = {
     .create_opts                    = &nfs_create_opts,
 
     .bdrv_has_zero_init             = nfs_has_zero_init,
+    .bdrv_has_zero_init_truncate    = nfs_has_zero_init,
     .bdrv_get_allocated_file_size   = nfs_get_allocated_file_size,
     .bdrv_co_truncate               = nfs_file_co_truncate,
 
diff --git a/block/parallels.c b/block/parallels.c
index 00fae12..7cd2714 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -835,7 +835,7 @@ static int parallels_open(BlockDriverState *bs, QDict *options, int flags,
         goto fail_options;
     }
 
-    if (!bdrv_has_zero_init(bs->file->bs)) {
+    if (!bdrv_has_zero_init_truncate(bs->file->bs)) {
         s->prealloc_mode = PRL_PREALLOC_MODE_FALLOCATE;
     }
 
diff --git a/block/qcow2.c b/block/qcow2.c
index 59cff1d..7c5a485 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -4632,6 +4632,33 @@ static ImageInfoSpecific *qcow2_get_specific_info(BlockDriverState *bs,
     return spec_info;
 }
 
+static int qcow2_has_zero_init(BlockDriverState *bs)
+{
+    BDRVQcow2State *s = bs->opaque;
+    bool preallocated;
+
+    if (qemu_in_coroutine()) {
+        qemu_co_mutex_lock(&s->lock);
+    }
+    /*
+     * Check preallocation status: Preallocated images have all L2
+     * tables allocated, nonpreallocated images have none.  It is
+     * therefore enough to check the first one.
+     */
+    preallocated = s->l1_size > 0 && s->l1_table[0] != 0;
+    if (qemu_in_coroutine()) {
+        qemu_co_mutex_unlock(&s->lock);
+    }
+
+    if (!preallocated) {
+        return 1;
+    } else if (bs->encrypted) {
+        return 0;
+    } else {
+        return bdrv_has_zero_init(s->data_file->bs);
+    }
+}
+
 static int qcow2_save_vmstate(BlockDriverState *bs, QEMUIOVector *qiov,
                               int64_t pos)
 {
@@ -5187,7 +5214,8 @@ BlockDriver bdrv_qcow2 = {
     .bdrv_child_perm      = bdrv_format_default_perms,
     .bdrv_co_create_opts  = qcow2_co_create_opts,
     .bdrv_co_create       = qcow2_co_create,
-    .bdrv_has_zero_init = bdrv_has_zero_init_1,
+    .bdrv_has_zero_init   = qcow2_has_zero_init,
+    .bdrv_has_zero_init_truncate = bdrv_has_zero_init_1,
     .bdrv_co_block_status = qcow2_co_block_status,
 
     .bdrv_co_preadv         = qcow2_co_preadv,
diff --git a/block/qed.c b/block/qed.c
index d0dcc5f..0d8fd50 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -1669,6 +1669,7 @@ static BlockDriver bdrv_qed = {
     .bdrv_co_create           = bdrv_qed_co_create,
     .bdrv_co_create_opts      = bdrv_qed_co_create_opts,
     .bdrv_has_zero_init       = bdrv_has_zero_init_1,
+    .bdrv_has_zero_init_truncate = bdrv_has_zero_init_1,
     .bdrv_co_block_status     = bdrv_qed_co_block_status,
     .bdrv_co_readv            = bdrv_qed_co_readv,
     .bdrv_co_writev           = bdrv_qed_co_writev,
diff --git a/block/raw-format.c b/block/raw-format.c
index bffd424..42c28cc 100644
--- a/block/raw-format.c
+++ b/block/raw-format.c
@@ -413,6 +413,11 @@ static int raw_has_zero_init(BlockDriverState *bs)
     return bdrv_has_zero_init(bs->file->bs);
 }
 
+static int raw_has_zero_init_truncate(BlockDriverState *bs)
+{
+    return bdrv_has_zero_init_truncate(bs->file->bs);
+}
+
 static int coroutine_fn raw_co_create_opts(const char *filename, QemuOpts *opts,
                                            Error **errp)
 {
@@ -572,6 +577,7 @@ BlockDriver bdrv_raw = {
     .bdrv_co_ioctl        = &raw_co_ioctl,
     .create_opts          = &raw_create_opts,
     .bdrv_has_zero_init   = &raw_has_zero_init,
+    .bdrv_has_zero_init_truncate = &raw_has_zero_init_truncate,
     .strong_runtime_opts  = raw_strong_runtime_opts,
     .mutable_opts         = mutable_opts,
 };
diff --git a/block/rbd.c b/block/rbd.c
index 59757b3..057af43 100644
--- a/block/rbd.c
+++ b/block/rbd.c
@@ -1288,6 +1288,7 @@ static BlockDriver bdrv_rbd = {
     .bdrv_co_create         = qemu_rbd_co_create,
     .bdrv_co_create_opts    = qemu_rbd_co_create_opts,
     .bdrv_has_zero_init     = bdrv_has_zero_init_1,
+    .bdrv_has_zero_init_truncate = bdrv_has_zero_init_1,
     .bdrv_get_info          = qemu_rbd_getinfo,
     .create_opts            = &qemu_rbd_create_opts,
     .bdrv_getlength         = qemu_rbd_getlength,
diff --git a/block/sheepdog.c b/block/sheepdog.c
index 31b0a82..773dfc6 100644
--- a/block/sheepdog.c
+++ b/block/sheepdog.c
@@ -3229,6 +3229,7 @@ static BlockDriver bdrv_sheepdog = {
     .bdrv_co_create               = sd_co_create,
     .bdrv_co_create_opts          = sd_co_create_opts,
     .bdrv_has_zero_init           = bdrv_has_zero_init_1,
+    .bdrv_has_zero_init_truncate  = bdrv_has_zero_init_1,
     .bdrv_getlength               = sd_getlength,
     .bdrv_get_allocated_file_size = sd_get_allocated_file_size,
     .bdrv_co_truncate             = sd_co_truncate,
diff --git a/block/ssh.c b/block/ssh.c
index 501933b..84d01e8 100644
--- a/block/ssh.c
+++ b/block/ssh.c
@@ -1390,6 +1390,7 @@ static BlockDriver bdrv_ssh = {
     .bdrv_co_create_opts          = ssh_co_create_opts,
     .bdrv_close                   = ssh_close,
     .bdrv_has_zero_init           = ssh_has_zero_init,
+    .bdrv_has_zero_init_truncate  = ssh_has_zero_init,
     .bdrv_co_readv                = ssh_co_readv,
     .bdrv_co_writev               = ssh_co_writev,
     .bdrv_getlength               = ssh_getlength,
diff --git a/block/vdi.c b/block/vdi.c
index b9845a4..806ba7f 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -542,7 +542,8 @@ static int coroutine_fn vdi_co_block_status(BlockDriverState *bs,
     *map = s->header.offset_data + (uint64_t)bmap_entry * s->block_size +
         index_in_block;
     *file = bs->file->bs;
-    return BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID;
+    return BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID |
+        (s->header.image_type == VDI_TYPE_STATIC ? BDRV_BLOCK_RECURSE : 0);
 }
 
 static int coroutine_fn
@@ -988,6 +989,17 @@ static void vdi_close(BlockDriverState *bs)
     error_free(s->migration_blocker);
 }
 
+static int vdi_has_zero_init(BlockDriverState *bs)
+{
+    BDRVVdiState *s = bs->opaque;
+
+    if (s->header.image_type == VDI_TYPE_STATIC) {
+        return bdrv_has_zero_init(bs->file->bs);
+    } else {
+        return 1;
+    }
+}
+
 static QemuOptsList vdi_create_opts = {
     .name = "vdi-create-opts",
     .head = QTAILQ_HEAD_INITIALIZER(vdi_create_opts.head),
@@ -1028,7 +1040,7 @@ static BlockDriver bdrv_vdi = {
     .bdrv_child_perm          = bdrv_format_default_perms,
     .bdrv_co_create      = vdi_co_create,
     .bdrv_co_create_opts = vdi_co_create_opts,
-    .bdrv_has_zero_init = bdrv_has_zero_init_1,
+    .bdrv_has_zero_init  = vdi_has_zero_init,
     .bdrv_co_block_status = vdi_co_block_status,
     .bdrv_make_empty = vdi_make_empty,
 
diff --git a/block/vhdx.c b/block/vhdx.c
index d6070b6..6a09d0a 100644
--- a/block/vhdx.c
+++ b/block/vhdx.c
@@ -1282,7 +1282,7 @@ static coroutine_fn int vhdx_co_writev(BlockDriverState *bs, int64_t sector_num,
                 /* Queue another write of zero buffers if the underlying file
                  * does not zero-fill on file extension */
 
-                if (bdrv_has_zero_init(bs->file->bs) == 0) {
+                if (bdrv_has_zero_init_truncate(bs->file->bs) == 0) {
                     use_zero_buffers = true;
 
                     /* zero fill the front, if any */
@@ -2075,6 +2075,30 @@ static int coroutine_fn vhdx_co_check(BlockDriverState *bs,
     return 0;
 }
 
+static int vhdx_has_zero_init(BlockDriverState *bs)
+{
+    BDRVVHDXState *s = bs->opaque;
+    int state;
+
+    /*
+     * Check the subformat: Fixed images have all BAT entries present,
+     * dynamic images have none (right after creation).  It is
+     * therefore enough to check the first BAT entry.
+     */
+    if (!s->bat_entries) {
+        return 1;
+    }
+
+    state = s->bat[0] & VHDX_BAT_STATE_BIT_MASK;
+    if (state == PAYLOAD_BLOCK_FULLY_PRESENT) {
+        /* Fixed subformat */
+        return bdrv_has_zero_init(bs->file->bs);
+    }
+
+    /* Dynamic subformat */
+    return 1;
+}
+
 static QemuOptsList vhdx_create_opts = {
     .name = "vhdx-create-opts",
     .head = QTAILQ_HEAD_INITIALIZER(vhdx_create_opts.head),
@@ -2128,7 +2152,7 @@ static BlockDriver bdrv_vhdx = {
     .bdrv_co_create_opts    = vhdx_co_create_opts,
     .bdrv_get_info          = vhdx_get_info,
     .bdrv_co_check          = vhdx_co_check,
-    .bdrv_has_zero_init     = bdrv_has_zero_init_1,
+    .bdrv_has_zero_init     = vhdx_has_zero_init,
 
     .create_opts            = &vhdx_create_opts,
 };
diff --git a/block/vmdk.c b/block/vmdk.c
index bd36ece..fd78fd0 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -1692,6 +1692,9 @@ static int coroutine_fn vmdk_co_block_status(BlockDriverState *bs,
         if (!extent->compressed) {
             ret |= BDRV_BLOCK_OFFSET_VALID;
             *map = cluster_offset + index_in_cluster;
+            if (extent->flat) {
+                ret |= BDRV_BLOCK_RECURSE;
+            }
         }
         *file = extent->file->bs;
         break;
diff --git a/block/vpc.c b/block/vpc.c
index d4776ee..b25aab0 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -737,7 +737,7 @@ static int coroutine_fn vpc_co_block_status(BlockDriverState *bs,
         *pnum = bytes;
         *map = offset;
         *file = bs->file->bs;
-        return BDRV_BLOCK_RAW | BDRV_BLOCK_OFFSET_VALID;
+        return BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID | BDRV_BLOCK_RECURSE;
     }
 
     qemu_co_mutex_lock(&s->lock);
diff --git a/blockdev.c b/blockdev.c
index 2e536dd..fbef684 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3782,6 +3782,7 @@ static void blockdev_mirror_common(const char *job_id, BlockDriverState *bs,
                                    bool has_replaces, const char *replaces,
                                    enum MirrorSyncMode sync,
                                    BlockMirrorBackingMode backing_mode,
+                                   bool zero_target,
                                    bool has_speed, int64_t speed,
                                    bool has_granularity, uint32_t granularity,
                                    bool has_buf_size, int64_t buf_size,
@@ -3890,7 +3891,7 @@ static void blockdev_mirror_common(const char *job_id, BlockDriverState *bs,
      */
     mirror_start(job_id, bs, target,
                  has_replaces ? replaces : NULL, job_flags,
-                 speed, granularity, buf_size, sync, backing_mode,
+                 speed, granularity, buf_size, sync, backing_mode, zero_target,
                  on_source_error, on_target_error, unmap, filter_node_name,
                  copy_mode, errp);
 }
@@ -3906,6 +3907,7 @@ void qmp_drive_mirror(DriveMirror *arg, Error **errp)
     int flags;
     int64_t size;
     const char *format = arg->format;
+    bool zero_target;
     int ret;
 
     bs = qmp_get_root_bs(arg->device, errp);
@@ -4007,6 +4009,10 @@ void qmp_drive_mirror(DriveMirror *arg, Error **errp)
         goto out;
     }
 
+    zero_target = (arg->sync == MIRROR_SYNC_MODE_FULL &&
+                   (arg->mode == NEW_IMAGE_MODE_EXISTING ||
+                    !bdrv_has_zero_init(target_bs)));
+
     ret = bdrv_try_set_aio_context(target_bs, aio_context, errp);
     if (ret < 0) {
         bdrv_unref(target_bs);
@@ -4015,7 +4021,8 @@ void qmp_drive_mirror(DriveMirror *arg, Error **errp)
 
     blockdev_mirror_common(arg->has_job_id ? arg->job_id : NULL, bs, target_bs,
                            arg->has_replaces, arg->replaces, arg->sync,
-                           backing_mode, arg->has_speed, arg->speed,
+                           backing_mode, zero_target,
+                           arg->has_speed, arg->speed,
                            arg->has_granularity, arg->granularity,
                            arg->has_buf_size, arg->buf_size,
                            arg->has_on_source_error, arg->on_source_error,
@@ -4055,6 +4062,7 @@ void qmp_blockdev_mirror(bool has_job_id, const char *job_id,
     AioContext *aio_context;
     BlockMirrorBackingMode backing_mode = MIRROR_LEAVE_BACKING_CHAIN;
     Error *local_err = NULL;
+    bool zero_target;
     int ret;
 
     bs = qmp_get_root_bs(device, errp);
@@ -4067,6 +4075,8 @@ void qmp_blockdev_mirror(bool has_job_id, const char *job_id,
         return;
     }
 
+    zero_target = (sync == MIRROR_SYNC_MODE_FULL);
+
     aio_context = bdrv_get_aio_context(bs);
     aio_context_acquire(aio_context);
 
@@ -4077,7 +4087,7 @@ void qmp_blockdev_mirror(bool has_job_id, const char *job_id,
 
     blockdev_mirror_common(has_job_id ? job_id : NULL, bs, target_bs,
                            has_replaces, replaces, sync, backing_mode,
-                           has_speed, speed,
+                           zero_target, has_speed, speed,
                            has_granularity, granularity,
                            has_buf_size, buf_size,
                            has_on_source_error, on_source_error,
diff --git a/docs/qemu-block-drivers.texi b/docs/qemu-block-drivers.texi
index 91ab0ec..c02547e 100644
--- a/docs/qemu-block-drivers.texi
+++ b/docs/qemu-block-drivers.texi
@@ -31,8 +31,8 @@ Supported options:
 @item preallocation
 Preallocation mode (allowed values: @code{off}, @code{falloc}, @code{full}).
 @code{falloc} mode preallocates space for image by calling posix_fallocate().
-@code{full} mode preallocates space for image by writing zeros to underlying
-storage.
+@code{full} mode preallocates space for image by writing data to underlying
+storage.  This data may or may not be zero, depending on the storage location.
 @end table
 
 @item qcow2
diff --git a/include/block/block.h b/include/block/block.h
index 89e4031..124ad40 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -443,6 +443,7 @@ int bdrv_pdiscard(BdrvChild *child, int64_t offset, int64_t bytes);
 int bdrv_co_pdiscard(BdrvChild *child, int64_t offset, int64_t bytes);
 int bdrv_has_zero_init_1(BlockDriverState *bs);
 int bdrv_has_zero_init(BlockDriverState *bs);
+int bdrv_has_zero_init_truncate(BlockDriverState *bs);
 bool bdrv_unallocated_blocks_are_zero(BlockDriverState *bs);
 bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs);
 int bdrv_block_status(BlockDriverState *bs, int64_t offset,
diff --git a/include/block/block_int.h b/include/block/block_int.h
index aa697f1..ceec8c2 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -419,9 +419,16 @@ struct BlockDriver {
     /*
      * Returns 1 if newly created images are guaranteed to contain only
      * zeros, 0 otherwise.
+     * Must return 0 if .bdrv_has_zero_init_truncate() returns 0.
      */
     int (*bdrv_has_zero_init)(BlockDriverState *bs);
 
+    /*
+     * Returns 1 if new areas added by growing the image with
+     * PREALLOC_MODE_OFF contain only zeros, 0 otherwise.
+     */
+    int (*bdrv_has_zero_init_truncate)(BlockDriverState *bs);
+
     /* Remove fd handlers, timers, and other event loop callbacks so the event
      * loop is no longer in use.  Called with no in-flight requests and in
      * depth-first traversal order with parents before child nodes.
@@ -1115,6 +1122,7 @@ BlockJob *commit_active_start(const char *job_id, BlockDriverState *bs,
  * @buf_size: The amount of data that can be in flight at one time.
  * @mode: Whether to collapse all images in the chain to the target.
  * @backing_mode: How to establish the target's backing chain after completion.
+ * @zero_target: Whether the target should be explicitly zero-initialized
  * @on_source_error: The action to take upon error reading from the source.
  * @on_target_error: The action to take upon error writing to the target.
  * @unmap: Whether to unmap target where source sectors only contain zeroes.
@@ -1134,6 +1142,7 @@ void mirror_start(const char *job_id, BlockDriverState *bs,
                   int creation_flags, int64_t speed,
                   uint32_t granularity, int64_t buf_size,
                   MirrorSyncMode mode, BlockMirrorBackingMode backing_mode,
+                  bool zero_target,
                   BlockdevOnError on_source_error,
                   BlockdevOnError on_target_error,
                   bool unmap, const char *filter_node_name,
diff --git a/qapi/block-core.json b/qapi/block-core.json
index e9364a4..e6edd64 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -4212,13 +4212,17 @@
 #
 # @file             Node to create the image format on
 # @size             Size of the virtual disk in bytes
+# @preallocation    Preallocation mode for the new image
+#                   (since: 4.2)
+#                   (default: off; allowed values: off, metadata, falloc, full)
 #
 # Since: 2.12
 ##
 { 'struct': 'BlockdevCreateOptionsLUKS',
   'base': 'QCryptoBlockCreateOptionsLUKS',
   'data': { 'file':             'BlockdevRef',
-            'size':             'size' } }
+            'size':             'size',
+            '*preallocation':   'PreallocMode' } }
 
 ##
 # @BlockdevCreateOptionsNfs:
@@ -5174,10 +5178,11 @@
 # @off: no preallocation
 # @metadata: preallocate only for metadata
 # @falloc: like @full preallocation but allocate disk space by
-#          posix_fallocate() rather than writing zeros.
-# @full: preallocate all data by writing zeros to device to ensure disk
-#        space is really available. @full preallocation also sets up
-#        metadata correctly.
+#          posix_fallocate() rather than writing data.
+# @full: preallocate all data by writing it to the device to ensure
+#        disk space is really available. This data may or may not be
+#        zero, depending on the image format and storage.
+#        @full preallocation also sets up metadata correctly.
 #
 # Since: 2.2
 ##
diff --git a/qemu-img.c b/qemu-img.c
index c920e35..7daa05e 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1578,6 +1578,7 @@ typedef struct ImgConvertState {
     bool has_zero_init;
     bool compressed;
     bool unallocated_blocks_are_zero;
+    bool target_is_new;
     bool target_has_backing;
     int64_t target_backing_sectors; /* negative if unknown */
     bool wr_in_order;
@@ -1975,9 +1976,11 @@ static int convert_do_copy(ImgConvertState *s)
     int64_t sector_num = 0;
 
     /* Check whether we have zero initialisation or can get it efficiently */
-    s->has_zero_init = s->min_sparse && !s->target_has_backing
-                     ? bdrv_has_zero_init(blk_bs(s->target))
-                     : false;
+    if (s->target_is_new && s->min_sparse && !s->target_has_backing) {
+        s->has_zero_init = bdrv_has_zero_init(blk_bs(s->target));
+    } else {
+        s->has_zero_init = false;
+    }
 
     if (!s->has_zero_init && !s->target_has_backing &&
         bdrv_can_write_zeroes_with_unmap(blk_bs(s->target)))
@@ -2428,6 +2431,8 @@ static int img_convert(int argc, char **argv)
         }
     }
 
+    s.target_is_new = !skip_create;
+
     flags = s.min_sparse ? (BDRV_O_RDWR | BDRV_O_UNMAP) : BDRV_O_RDWR;
     ret = bdrv_parse_cache_mode(cache, &flags, &writethrough);
     if (ret < 0) {
diff --git a/qemu-img.texi b/qemu-img.texi
index c8e9bba..b5156d6 100644
--- a/qemu-img.texi
+++ b/qemu-img.texi
@@ -666,8 +666,8 @@ Supported options:
 @item preallocation
 Preallocation mode (allowed values: @code{off}, @code{falloc}, @code{full}).
 @code{falloc} mode preallocates space for image by calling posix_fallocate().
-@code{full} mode preallocates space for image by writing zeros to underlying
-storage.
+@code{full} mode preallocates space for image by writing data to underlying
+storage.  This data may or may not be zero, depending on the storage location.
 @end table
 
 @item qcow2
diff --git a/tests/qemu-iotests/041 b/tests/qemu-iotests/041
index 26bf170..8bc8f81 100755
--- a/tests/qemu-iotests/041
+++ b/tests/qemu-iotests/041
@@ -741,8 +741,15 @@ class TestUnbackedSource(iotests.QMPTestCase):
     def setUp(self):
         qemu_img('create', '-f', iotests.imgfmt, test_img,
                  str(TestUnbackedSource.image_len))
-        self.vm = iotests.VM().add_drive(test_img)
+        self.vm = iotests.VM()
         self.vm.launch()
+        result = self.vm.qmp('blockdev-add', node_name='drive0',
+                             driver=iotests.imgfmt,
+                             file={
+                                 'driver': 'file',
+                                 'filename': test_img,
+                             })
+        self.assert_qmp(result, 'return', {})
 
     def tearDown(self):
         self.vm.shutdown()
@@ -751,7 +758,7 @@ class TestUnbackedSource(iotests.QMPTestCase):
 
     def test_absolute_paths_full(self):
         self.assert_no_active_block_jobs()
-        result = self.vm.qmp('drive-mirror', device='drive0',
+        result = self.vm.qmp('drive-mirror', job_id='drive0', device='drive0',
                              sync='full', target=target_img,
                              mode='absolute-paths')
         self.assert_qmp(result, 'return', {})
@@ -760,7 +767,7 @@ class TestUnbackedSource(iotests.QMPTestCase):
 
     def test_absolute_paths_top(self):
         self.assert_no_active_block_jobs()
-        result = self.vm.qmp('drive-mirror', device='drive0',
+        result = self.vm.qmp('drive-mirror', job_id='drive0', device='drive0',
                              sync='top', target=target_img,
                              mode='absolute-paths')
         self.assert_qmp(result, 'return', {})
@@ -769,13 +776,60 @@ class TestUnbackedSource(iotests.QMPTestCase):
 
     def test_absolute_paths_none(self):
         self.assert_no_active_block_jobs()
-        result = self.vm.qmp('drive-mirror', device='drive0',
+        result = self.vm.qmp('drive-mirror', job_id='drive0', device='drive0',
                              sync='none', target=target_img,
                              mode='absolute-paths')
         self.assert_qmp(result, 'return', {})
         self.complete_and_wait()
         self.assert_no_active_block_jobs()
 
+    def test_existing_full(self):
+        qemu_img('create', '-f', iotests.imgfmt, target_img,
+                 str(self.image_len))
+        qemu_io('-c', 'write -P 42 0 64k', target_img)
+
+        self.assert_no_active_block_jobs()
+        result = self.vm.qmp('drive-mirror', job_id='drive0', device='drive0',
+                             sync='full', target=target_img, mode='existing')
+        self.assert_qmp(result, 'return', {})
+        self.complete_and_wait()
+        self.assert_no_active_block_jobs()
+
+        result = self.vm.qmp('blockdev-del', node_name='drive0')
+        self.assert_qmp(result, 'return', {})
+
+        self.assertTrue(iotests.compare_images(test_img, target_img),
+                        'target image does not match source after mirroring')
+
+    def test_blockdev_full(self):
+        qemu_img('create', '-f', iotests.imgfmt, target_img,
+                 str(self.image_len))
+        qemu_io('-c', 'write -P 42 0 64k', target_img)
+
+        result = self.vm.qmp('blockdev-add', node_name='target',
+                             driver=iotests.imgfmt,
+                             file={
+                                 'driver': 'file',
+                                 'filename': target_img,
+                             })
+        self.assert_qmp(result, 'return', {})
+
+        self.assert_no_active_block_jobs()
+        result = self.vm.qmp('blockdev-mirror', job_id='drive0', device='drive0',
+                             sync='full', target='target')
+        self.assert_qmp(result, 'return', {})
+        self.complete_and_wait()
+        self.assert_no_active_block_jobs()
+
+        result = self.vm.qmp('blockdev-del', node_name='drive0')
+        self.assert_qmp(result, 'return', {})
+
+        result = self.vm.qmp('blockdev-del', node_name='target')
+        self.assert_qmp(result, 'return', {})
+
+        self.assertTrue(iotests.compare_images(test_img, target_img),
+                        'target image does not match source after mirroring')
+
 class TestGranularity(iotests.QMPTestCase):
     image_len = 10 * 1024 * 1024 # MB
 
diff --git a/tests/qemu-iotests/041.out b/tests/qemu-iotests/041.out
index e071d0b..2c448b4 100644
--- a/tests/qemu-iotests/041.out
+++ b/tests/qemu-iotests/041.out
@@ -1,5 +1,5 @@
-........................................................................................
+..........................................................................................
 ----------------------------------------------------------------------
-Ran 88 tests
+Ran 90 tests
 
 OK
diff --git a/tests/qemu-iotests/122 b/tests/qemu-iotests/122
index 85c3a8d..059011e 100755
--- a/tests/qemu-iotests/122
+++ b/tests/qemu-iotests/122
@@ -257,6 +257,23 @@ for min_sparse in 4k 8k; do
     $QEMU_IMG map --output=json "$TEST_IMG".orig | _filter_qemu_img_map
 done
 
+
+echo
+echo '=== -n to a non-zero image ==='
+echo
+
+# Keep source zero
+_make_test_img 64M
+
+# Output is not zero, but has bdrv_has_zero_init() == 1
+TEST_IMG="$TEST_IMG".orig _make_test_img 64M
+$QEMU_IO -c "write -P 42 0 64k" "$TEST_IMG".orig | _filter_qemu_io
+
+# Convert with -n, which should not assume that the target is zeroed
+$QEMU_IMG convert -O $IMGFMT -n "$TEST_IMG" "$TEST_IMG".orig
+
+$QEMU_IMG compare "$TEST_IMG" "$TEST_IMG".orig
+
 # success, all done
 echo '*** done'
 rm -f $seq.full
diff --git a/tests/qemu-iotests/122.out b/tests/qemu-iotests/122.out
index c576705..849b6cc 100644
--- a/tests/qemu-iotests/122.out
+++ b/tests/qemu-iotests/122.out
@@ -220,4 +220,12 @@ convert -c -S 8k
 { "start": 9216, "length": 8192, "depth": 0, "zero": true, "data": false},
 { "start": 17408, "length": 1024, "depth": 0, "zero": false, "data": true},
 { "start": 18432, "length": 67090432, "depth": 0, "zero": true, "data": false}]
+
+=== -n to a non-zero image ===
+
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
+Formatting 'TEST_DIR/t.IMGFMT.orig', 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)
+Images are identical.
 *** done
diff --git a/tests/qemu-iotests/141 b/tests/qemu-iotests/141
index 2197a82..8c2ae79 100755
--- a/tests/qemu-iotests/141
+++ b/tests/qemu-iotests/141
@@ -58,16 +58,21 @@ test_blockjob()
               }}}" \
         'return'
 
+    # If "$2" is an event, we may or may not see it before the
+    # {"return": {}}.  Therefore, filter the {"return": {}} out both
+    # here and in the next command.  (Naturally, if we do not see it
+    # here, we will see it before the next command can be executed,
+    # so it will appear in the next _send_qemu_cmd's output.)
     _send_qemu_cmd $QEMU_HANDLE \
         "$1" \
         "$2" \
-        | _filter_img_create
+        | _filter_img_create | _filter_qmp_empty_return
 
     # We want this to return an error because the block job is still running
     _send_qemu_cmd $QEMU_HANDLE \
         "{'execute': 'blockdev-del',
           'arguments': {'node-name': 'drv0'}}" \
-        'error' | _filter_generated_node_ids
+        'error' | _filter_generated_node_ids | _filter_qmp_empty_return
 
     _send_qemu_cmd $QEMU_HANDLE \
         "{'execute': 'block-job-cancel',
diff --git a/tests/qemu-iotests/141.out b/tests/qemu-iotests/141.out
index 4d71d9d..dbd3bde 100644
--- a/tests/qemu-iotests/141.out
+++ b/tests/qemu-iotests/141.out
@@ -10,7 +10,6 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1048576 backing_file=TEST_DIR/m.
 Formatting 'TEST_DIR/o.IMGFMT', fmt=IMGFMT size=1048576 backing_file=TEST_DIR/t.IMGFMT backing_fmt=IMGFMT
 {"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": {}}
 {"error": {"class": "GenericError", "desc": "Node drv0 is in use"}}
 {"return": {}}
 {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "aborting", "id": "job0"}}
@@ -27,7 +26,6 @@ Formatting 'TEST_DIR/o.IMGFMT', fmt=IMGFMT size=1048576 backing_file=TEST_DIR/t.
 {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "running", "id": "job0"}}
 {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "ready", "id": "job0"}}
 {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_READY", "data": {"device": "job0", "len": 0, "offset": 0, "speed": 0, "type": "mirror"}}
-{"return": {}}
 {"error": {"class": "GenericError", "desc": "Node 'drv0' is busy: block device is in use by block job: mirror"}}
 {"return": {}}
 {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "waiting", "id": "job0"}}
@@ -42,7 +40,6 @@ Formatting 'TEST_DIR/o.IMGFMT', fmt=IMGFMT size=1048576 backing_file=TEST_DIR/t.
 {"return": {}}
 {"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": "ready", "id": "job0"}}
 {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_READY", "data": {"device": "job0", "len": 0, "offset": 0, "speed": 0, "type": "commit"}}
 {"error": {"class": "GenericError", "desc": "Node 'drv0' is busy: block device is in use by block job: commit"}}
@@ -61,7 +58,6 @@ wrote 1048576/1048576 bytes at offset 0
 {"return": {}}
 {"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": {}}
 {"error": {"class": "GenericError", "desc": "Node drv0 is in use"}}
 {"return": {}}
 {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "aborting", "id": "job0"}}
@@ -77,7 +73,6 @@ wrote 1048576/1048576 bytes at offset 0
 {"return": {}}
 {"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": {}}
 {"error": {"class": "GenericError", "desc": "Node drv0 is in use"}}
 {"return": {}}
 {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "aborting", "id": "job0"}}
diff --git a/tests/qemu-iotests/188 b/tests/qemu-iotests/188
index be7278a..afca44d 100755
--- a/tests/qemu-iotests/188
+++ b/tests/qemu-iotests/188
@@ -48,7 +48,7 @@ SECRETALT="secret,id=sec0,data=platypus"
 
 _make_test_img --object $SECRET -o "encrypt.format=luks,encrypt.key-secret=sec0,encrypt.iter-time=10" $size
 
-IMGSPEC="driver=$IMGFMT,file.filename=$TEST_IMG,encrypt.key-secret=sec0"
+IMGSPEC="driver=$IMGFMT,encrypt.key-secret=sec0,file.filename=$TEST_IMG"
 
 QEMU_IO_OPTIONS=$QEMU_IO_OPTIONS_NO_FMT
 
@@ -68,6 +68,24 @@ echo
 echo "== verify open failure with wrong password =="
 $QEMU_IO --object $SECRETALT -c "read -P 0xa 0 $size" --image-opts $IMGSPEC | _filter_qemu_io | _filter_testdir
 
+_cleanup_test_img
+
+echo
+echo "== verify that has_zero_init returns false when preallocating =="
+
+# Empty source file
+if [ -n "$TEST_IMG_FILE" ]; then
+    TEST_IMG_FILE="${TEST_IMG_FILE}.orig" _make_test_img $size
+else
+    TEST_IMG="${TEST_IMG}.orig" _make_test_img $size
+fi
+
+$QEMU_IMG convert -O "$IMGFMT" --object $SECRET \
+    -o "encrypt.format=luks,encrypt.key-secret=sec0,encrypt.iter-time=10,preallocation=metadata" \
+    "${TEST_IMG}.orig" "$TEST_IMG"
+
+$QEMU_IMG compare --object $SECRET --image-opts "${IMGSPEC}.orig" "$IMGSPEC"
+
 
 # success, all done
 echo "*** done"
diff --git a/tests/qemu-iotests/188.out b/tests/qemu-iotests/188.out
index 97b1402..c568ef3 100644
--- a/tests/qemu-iotests/188.out
+++ b/tests/qemu-iotests/188.out
@@ -15,4 +15,8 @@ read 16777216/16777216 bytes at offset 0
 
 == verify open failure with wrong password ==
 qemu-io: can't open: Invalid password, cannot unlock any keyslot
+
+== verify that has_zero_init returns false when preallocating ==
+Formatting 'TEST_DIR/t.IMGFMT.orig', fmt=IMGFMT size=16777216
+Images are identical.
 *** done
diff --git a/tests/qemu-iotests/common.filter b/tests/qemu-iotests/common.filter
index 35fddc7..8e9235d 100644
--- a/tests/qemu-iotests/common.filter
+++ b/tests/qemu-iotests/common.filter
@@ -219,5 +219,10 @@ _filter_nbd()
         -e 's#\(foo\|PORT/\?\|.sock\): Failed to .*$#\1#'
 }
 
+_filter_qmp_empty_return()
+{
+    grep -v '{"return": {}}'
+}
+
 # make sure this script returns success
 true
diff --git a/tests/test-block-iothread.c b/tests/test-block-iothread.c
index e81b5b8..926577b 100644
--- a/tests/test-block-iothread.c
+++ b/tests/test-block-iothread.c
@@ -612,7 +612,7 @@ static void test_propagate_mirror(void)
 
     /* Start a mirror job */
     mirror_start("job0", src, target, NULL, JOB_DEFAULT, 0, 0, 0,
-                 MIRROR_SYNC_MODE_NONE, MIRROR_OPEN_BACKING_CHAIN,
+                 MIRROR_SYNC_MODE_NONE, MIRROR_OPEN_BACKING_CHAIN, false,
                  BLOCKDEV_ON_ERROR_REPORT, BLOCKDEV_ON_ERROR_REPORT,
                  false, "filter_node", MIRROR_COPY_MODE_BACKGROUND,
                  &error_abort);