On 02.12.19 13:15, Andrey Shinkevich wrote: > Allow writing all the data compressed through the filter driver. > The written data will be aligned by the cluster size. > Based on the QEMU current implementation, that data can be written to > unallocated clusters only. May be used for a backup job. > > Suggested-by: Max Reitz <mre...@redhat.com> > Signed-off-by: Andrey Shinkevich <andrey.shinkev...@virtuozzo.com> > Reviewed-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com> > --- > block/Makefile.objs | 1 + > block/filter-compress.c | 168 > ++++++++++++++++++++++++++++++++++++++++++++++++ > qapi/block-core.json | 10 +-- > 3 files changed, 175 insertions(+), 4 deletions(-) > create mode 100644 block/filter-compress.c
[...]
> diff --git a/block/filter-compress.c b/block/filter-compress.c
> new file mode 100644
> index 0000000..4d756ea
> --- /dev/null
> +++ b/block/filter-compress.c
> @@ -0,0 +1,168 @@
[...]
> +static int compress_open(BlockDriverState *bs, QDict *options, int flags,
> + Error **errp)
> +{
> + bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file, false,
> + errp);
> + if (!bs->file) {
> + return -EINVAL;
> + }
> +
> + if (!bs->file->bs->drv || !block_driver_can_compress(bs->file->bs->drv))
> {
> + error_setg(errp,
> + "Compression is not supported for underlying format: %s",
> + bdrv_get_format_name(bs->file->bs));
bdrv_get_format_name() returns NULL if bs->file->bs->drv is NULL. I’m
sure g_strdup_vprintf() handles %s with a NULL string gracefully in
practice, but I can’t find that specified anywhere. So even though I’m
well aware I’m being a bit stupid about a minor edge case, I’m hesitant
to accept this patch as-is.
Obviously the solution can be as simple as bdrv_get_format_name(...) ?:
"(no format)".
Well, actually, I can be a bit less stupid about it and just propose
merging that change in myself. Would that be OK for you?
(The rest looks good to me.)
Max
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