On 05/05/2018 03:49 AM, Ivan Ren wrote:
> qemu-img info with a block device which has a qcow2 format always
> return 0 for disk size, and this can not reflect the qcow2 size
> and the used space of the block device. This patch return the
> allocated size of qcow2 as the disk size.
>
This has hit over a month old; I only skimmed the comments on V1 from
Max and Eric. Is this something we still want?
--js
> Signed-off-by: Ivan Ren <ivan...@tencent.com>
> ---
> block/qcow2.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 54 insertions(+)
>
> This version differs from the previous:
> (1).Accumulate all non-0 refcount cluster as the allocated size instead the
> highest offset.
> (2).Simplify the implementation by just check the refcount info.
>
> diff --git a/block/qcow2.c b/block/qcow2.c
> index ef68772..e64469a 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -4493,6 +4493,59 @@ static QemuOptsList qcow2_create_opts = {
> }
> };
>
> +/* Get allocated space of qcow2, aligned to cluster_size */
> +static int64_t qcow2_get_allocated_size(BlockDriverState *bs)
> +{
> + int64_t allocated_cluster_count = 0;
> + uint64_t refcount;
> + int64_t i, j, begin_index, end_index;
> +
> + BDRVQcow2State *s = bs->opaque;
> +
> + /* Traverse refcount table */
> + for (i = 0; i < s->refcount_table_size; i++) {
> + if (s->refcount_table[i] & REFT_OFFSET_MASK) {
> + begin_index = i * s->refcount_block_size;
> + end_index = begin_index + s->refcount_block_size;
> + for (j = begin_index; j < end_index; j++) {
> + if (qcow2_get_refcount(bs, j, &refcount) < 0) {
> + continue;
> + }
> + if (refcount > 0) {
> + allocated_cluster_count++;
> + }
> + }
> + }
> +
> + }
> +
> + return allocated_cluster_count * s->cluster_size;
> +}
> +
> +static int64_t qcow2_get_allocated_file_size(BlockDriverState *bs)
> +{
> + int64_t ret = 0;
> +
> + /* Get through bs->file first */
> + if (bs->file) {
> + ret = bdrv_get_allocated_file_size(bs->file->bs);
> + }
> +
> + /*
> + * If ret < 0, some error may happen to the underlying media, return the
> + * error directly.
> + * If ret == 0, means length get from bs->file is 0, which is impossible
> + * for a normal file because of the qcow2 header. In this case, the
> + * underlying media may be a block device or anything else that can't
> + * return a suitable size. So we get the allocated size of qcow2 instead.
> + */
> + if (!ret) {
> + ret = qcow2_get_allocated_size(bs);
> + }
> +
> + return ret;
> +}
> +
> BlockDriver bdrv_qcow2 = {
> .format_name = "qcow2",
> .instance_size = sizeof(BDRVQcow2State),
> @@ -4516,6 +4569,7 @@ BlockDriver bdrv_qcow2 = {
> .bdrv_co_pwrite_zeroes = qcow2_co_pwrite_zeroes,
> .bdrv_co_pdiscard = qcow2_co_pdiscard,
> .bdrv_truncate = qcow2_truncate,
> + .bdrv_get_allocated_file_size = qcow2_get_allocated_file_size,
> .bdrv_co_pwritev_compressed = qcow2_co_pwritev_compressed,
> .bdrv_make_empty = qcow2_make_empty,
>
>
