diff options
Diffstat (limited to 'block')
| -rw-r--r-- | block/qcow2.c | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/block/qcow2.c b/block/qcow2.c index 2fb43c6f7e..9727ae8fe3 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -3503,6 +3503,28 @@ qcow2_co_create(BlockdevCreateOptions *create_options, Error **errp) ret = -EINVAL; goto out; } + if (qcow2_opts->data_file_raw && + qcow2_opts->preallocation == PREALLOC_MODE_OFF) + { + /* + * data-file-raw means that "the external data file can be + * read as a consistent standalone raw image without looking + * at the qcow2 metadata." It does not say that the metadata + * must be ignored, though (and the qcow2 driver in fact does + * not ignore it), so the L1/L2 tables must be present and + * give a 1:1 mapping, so you get the same result regardless + * of whether you look at the metadata or whether you ignore + * it. + */ + qcow2_opts->preallocation = PREALLOC_MODE_METADATA; + + /* + * Cannot use preallocation with backing files, but giving a + * backing file when specifying data_file_raw is an error + * anyway. + */ + assert(!qcow2_opts->has_backing_file); + } if (qcow2_opts->data_file) { if (version < 3) { @@ -4238,6 +4260,18 @@ static int coroutine_fn qcow2_co_truncate(BlockDriverState *bs, int64_t offset, error_setg_errno(errp, -ret, "Failed to grow the L1 table"); goto fail; } + + if (data_file_is_raw(bs) && prealloc == PREALLOC_MODE_OFF) { + /* + * When creating a qcow2 image with data-file-raw, we enforce + * at least prealloc=metadata, so that the L1/L2 tables are + * fully allocated and reading from the data file will return + * the same data as reading from the qcow2 image. When the + * image is grown, we must consequently preallocate the + * metadata structures to cover the added area. + */ + prealloc = PREALLOC_MODE_METADATA; + } } switch (prealloc) { |